[Technical Field]
[0001] The present invention relates to a saddle type vehicle
[Background Art]
[0002] For among OHC type internal combustion engines wherein a valve mechanism such as
a camshaft is configured on a cylinder head, a variable valve apparatus wherein a
valve timing can be changed is already known. In the variable valve apparatus of the
type just described, rocker arms for converting and transmitting rotation of the camshaft
into and as opening and closing motion of engine valves are provided adjacent each
other. A connection pin moves in the rocker arms provided adjacent each other. The
connection pin is movable between a connection position in which it connects the rocker
arms to each other for integral rocking motion and a disconnection position in which
it allows the rocker arms to rock independently of each other thereby to change the
valve timing.
[0003] An example of a variable valve apparatus has been proposed in a prior application
by the applicant same as that of the present application (refer to Japanese Patent
Laid-Open No.
2012-77741; in the following also referred to as Patent Document 1). In the variable valve apparatus,
a solenoid is used as a pressing force generation source for moving the connection
pin. An operating portion or rod of the solenoid moves the connection pin through
a push rod ((power) transmission rod or pressing force transmission member) supported
for sliding movement on the cylinder head.
[0004] In the OHC type internal combustion engine disclosed in Patent Document 1, an ignition
plug is provided in a projecting manner on a wall face of the cylinder head to which
the solenoid is attached.
[0005] Since the ignition plug is mounted on the same wall face in such a manner that it
is inserted obliquely from the head cover side, upon maintenance of the ignition plug,
the ignition plug is moved to be mounted or dismounted in a direction of an axial
line directed by the ignition plug in the mounted state.
[0006] In the variable valve apparatus disclosed in Patent Document 1, the operating rod
of the solenoid is inserted in a sliding hole of the cylinder head configured to support
the push rod (power transmission rod) for sliding motion. Further, a sandwiched inner
space (space) sandwiched between the operating rod and the push rod is formed in the
same sliding hole, and an oil supply hole (oil supplying hole) communicated with the
sandwiched inner space is formed above the sandwiched inner space.
[0007] The variable valve apparatus has a function as an oil damper which suppresses, when
the sandwiched inner space is filled with oil supplied from the oil supply hole, collision
of the operating rod with the push rod by operation of the solenoid and buffers an
impact and vibration by the collision.
[0008] In the variable valve apparatus disclosed in Patent Document 1, the connection pin
which moves in the rocker arm is disposed at a position swollen upwardly (head cover
side in the cylinder axial line direction) with respect to a rocker arm shaft between
the rocker arm shaft and a roller which contacts with a cam lobe of an end portion
of the rocker arm on the camshaft side. Also the transmission rod which acts upon
the connection pin is disposed on an upwardly swollen portion of an upper end face
of the cylinder head at a mating face position between the cylinder head and the head
cover above the rocker arm shaft.
[Summary of the Invention]
[Problem to Be Solved by the Invention]
[0009] In Patent Document 1, the solenoid is positioned comparatively near to the head cover
rather than the ignition plug, and the axial line directed by the ignition plug as
viewed in the direction of an axial line of the cylinder overlaps with the solenoid
as shown in figure 2 of Patent Document 1. Therefore, when the ignition plug is moved
to be mounted or dismounted in the axial line direction directed by the ignition plug,
the solenoid makes an obstacle and the maintenance operation is not easy.
[0010] JP 03-029486 B2 discloses a cycle suspension reciprocating type internal combustion engine. A cam
side intake rocker arm, a valve side intake rocker arm and a timing gear are fitted
in a rocker arm shaft. Shift pins are fitted in these rocker arms free of slide motion.
[0011] Particularly, where the OHC type internal combustion engine is mounted on a saddle
type vehicle in which it is not easy to assure a length of the cylinder head in the
cylinder axial line direction, the ignition plug and the solenoid are likely to be
positioned near to each other. This makes it further difficult to assure the maintenance
space around the ignition plug.
[0012] A typical saddle type vehicle is disclosed for example in document
EP 2543834 A1.
[0013] The present invention has been made in view of such a subject as just described and
provides a variable valve apparatus for an OHC type internal combustion engine which
can keep a good maintenance performance of an ignition plug while miniaturization
of a cylinder head is achieved. To this end, a pressing force generation source attached
to a wall face of a cylinder head to which the ignition plug is attached is disposed
at a position which is not far from the ignition plug and at which the pressing force
generation source does not make an obstacle to a mounting and dismounting operation
of the ignition plug.
[0014] Moreover, the oil supply hole of Patent Document 1 is formed at a position at which
it fully faces the sandwiched inner space between the operating rod and the push rod
when the solenoid is in an inactive state. Therefore, if, by the operation of the
solenoid, the operating rod starts movement toward the push rod, then the oil filled
in the sandwiched inner space is sandwiched and is likely to overflow from the oil
supply hole and there is the possibility that the function as the oil damper degrades
arising from coming off of the oil. Therefore, it is desired to utilize the function
as the oil damper more effectively.
[0015] The present invention has been made in view of such a situation as described above,
it is a further object of the present invention to provide a variable valve apparatus
for an OHC type internal combustion engine capable of enhancing a function as an oil
damper by oil to be supplied between an operating rod and a push rod.
[0016] Since the rocker arm has the upwardly swollen portion in order to dispose the connection
pin in this manner, the rocker arm itself is likely to increase in size toward the
head cover side in the cylinder axial line direction. Further, in order to dispose
the transmission rod, it sometimes has a swollen portion which is swollen to a position
above the upper end face of the cylinder head. From those, also the cylinder head
and the head cover increase in size.
[0017] Further, the transmission rod serving as a pressing force transmission member is
positioned on a mating face between the cylinder head and the head cover above the
rocker arm shaft. Therefore, also the solenoid serving as a pressing force generation
source is provided on the head cover side in the cylinder axial line direction. Consequently,
there is the possibility that the cylinder head and the head cover may further increase
in size in the cylinder axial line direction.
[0018] The present invention has been made in such a situation as described above, and a
further object of the present invention resides in provision of a variable valve apparatus
for an OHC type internal combustion engine wherein increase in size of a cylinder
head and a head cover can be prevented. To this end, a connection pin and a pressing
force transmission member are disposed as near as possible to a crankcase side in
the cylinder axial line direction.
[Means for Solving the Problem]
[0019] The object of the present invention is achieved by the subject-matter of the independent
claim. The dependent claims study further the central idea of the present invention.
[0020] In order to attain the object described above, a saddle type vehicle comprising,
supported for rocking motion on a vehicle body frame, a power unit (20) including
an OHC type internal combustion engine (30) and a belt-type continuously variable
transmission (21). The OHC type internal combustion engine (30) has a cylinder axial
line (Cc) tilted forward greatly and being provided therein with a plurality of rocker
arms (57, 58) arrayed and supported for rocking motion in a mutually neighboring relationship
on a rocker arm shaft (55) and operable in an interlocking relationship with engine
valves (61, 62). A connection pin (71) is fitted for movement in an axial direction
of the rocker arm shaft (55) in the rocker arms (57, 58) positioned adjacent each
other being provided to be movable between a connection position at which the connection
pin (71) connects the rocker arms (57, 58) positioned adjacent each other to each
other for integral rocking motion and a disconnection position at which the connection
pin (71) disconnects the rocker arms (57, 58) from each other to allow independent
rocking motion of each of the rocker arms (57, 58). A pressing force transmission
member (74, 76) is provided which transmits pressing force of a pressing force generation
source (75) disposed outside the OHC type internal combustion engine (30) to the connection
pin (71) to move the connection pin (71) in the vehicle widthwise direction. The OHC
type internal combustion engine (30) has side walls (100L, 100R) directed in the vehicle
widthwise direction and side walls (100U, 100S) directed in the vertical direction,
the side walls together assuming a rectangular tubular shape. The pressing force generation
source (75) is attached to one of the side walls (100L, 100R) directed in the vehicle
widthwise direction, and part of the vehicle body frame is provided on an outer side
of the pressing force generation source (75) in the vehicle widthwise direction. The
vehicle body frame includes a head pipe (2), a down tube (3) extending downwardly
from the head pipe (2), and a pair of left and right floor pipes (4) extending rearwardly
below a floor section (1c), which is disposed between a vehicle body front section
(1f) and a vehicle body rear section (1r), from the down tube (3), rising obliquely
upwardly at a rear portion of the floor section (1c) and extending rearwardly. The
pressing force generation source (75) is located forwardly of those rear portions
of the floor pipes (4) which rise obliquely upwardly and extend rearwardly, as viewed
in side view, wherein the vehicle body rear section (1r) including the pressing force
generation source (75) is covered from left and right sides with a body cover (29e).
[0021] Moreover,
there is provided a variable valve apparatus for an OHC type internal combustion engine
which includes a crankcase (31), a cylinder block (32) and a cylinder head (33) placed
in order on the crankcase (31) and fastened together by a plurality of stud bolts
(180) extending through the cylinder block (32) and the cylinder head (33) in a cylinder
axial line direction, a plurality of rocker arms (57, 58) arrayed and supported for
rocking motion in a mutually neighboring relationship on a rocker arm shaft (55) in
the inside of the cylinder head (33) and operable in an interlocking relationship
with engine valves (61, 62), and a head cover (34) placed on the cylinder head (33)
to cover the cylinder head (33), the variable valve apparatus including:
a connection pin (71) fitted for movement in an axial direction of the rocker arm
shaft (55) in the rocker arms (57, 58) positioned adjacent each other and movable
between a connection position at which the connection pin (71) connects the rocker
arms (57,58) positioned adjacent each other to each other for integral rocking motion
and a disconnection position at which the connection pin (71) disconnects the rocker
arms (57, 58) from each other to allow independent rocking motion of each of the rocker
arms (57, 58); and
a pressing force transmission member (74, 76) configured to transmit pressing force
of a pressing force generation source (75) disposed outside the cylinder head (33)
to the connection pin (71) to move the connection pin (71);
the pressing force generation source (75) being attached to a wall face (100L) of
the cylinder head (33) on which an ignition plug (49) is provided in a projecting
manner;
an accommodation case (77, 78) which accommodates a main body of the pressing force
generation source (75) therein being provided at a position at which the accommodation
case (77, 78) does not overlap with an ignition plug center axial line (Cs), which
is directed by the ignition plug (49), as viewed in the cylinder axial line direction.
[0022] The variable valve apparatus for an OHC type internal combustion engine can be further
configured such that
the pressing force generation source (75) is positioned on the head cover (34) side
with respect to the ignition plug (49).
[0023] The variable valve apparatus for an OHC type internal combustion engine can be further
configured such that
the pressing force transmission member (74, 76) is provided for sliding movement on
the cylinder head (33).
[0024] The variable valve apparatus for an OHC type internal combustion engine can be further
configured such that
the pressing force generation source (75) has a plurality of attachment arm portions
(77pr, 77qr, 77rr) formed around the accommodation case (77, 78) so as to extend radially
along the wall face (100L) of the cylinder head (33), and
the attachment arm portions (77pr, 77qr, 77rr) are attached only to the cylinder head
(33).
[0025] The variable valve apparatus for an OHC type internal combustion engine can be further
configured such that,
from among the attachment arm portions (77pr, 77qr, 77rr), the attachment arm portion
(77pr) which extends in a direction overlapping with the ignition plug center axial
line (Cs) as viewed in the cylinder axial line direction has a recessed portion (77d)
formed thereon so as to be open toward the ignition plug (49) side in such a manner
that the recessed portion (77d) crosses but keeps away from the ignition plug center
axial line (Cs).
[0026] The variable valve apparatus for an OHC type internal combustion engine can be further
configured such that,
on the cylinder head (33), rib portions (103pr, 103qr, 103rr) with which the attachment
arm portions (77pr, 77qr, 77rr) extending from the periphery of the accommodation
case (77, 78) are abutted and attachment boss portions (103p, 103q, 103r) at end portions
of the rib portions (103pr, 103qr, 103rr) are formed in a projecting manner, and the
attachment arm portions (77pr, 77qr, 77rr) are attached to the attachment boss portions
(103p, 103q, 103r).
[0027] The variable valve apparatus for an OHC type internal combustion engine can be further
configured such that
the accommodation case (77, 78) and the attachment arm portions (77pr, 77qr, 77rr)
of the pressing force generation source (75) are made of a metal.
[0028] The variable valve apparatus for an OHC type internal combustion engine can be further
configured such that,
on the wall face (100L) to which the pressing force generation source (75) of the
cylinder head (33) is attached, an oil passage (133) is formed in the proximity of
the pressing force generation source (75).
[0029] The variable valve apparatus for an OHC type internal combustion engine can be further
configured such that
the OHC type internal combustion engine (30) is mounted on a vehicle body frame of
a saddle type vehicle (1) in a posture in which a cylinder axial line (Cc) is tilted
forward greatly to a position proximate to a horizontal position,
the pressing force generation source (75) is attached to the side wall face (100L)
of the cylinder head (33) directed in the vehicle widthwise direction, and
the pressing force generation source (75) is covered on the outer sides thereof in
the vehicle widthwise direction with part (6) of the vehicle body frame.
[0030] The variable valve apparatus for an OHC type internal combustion engine can be further
configured such that
a water pump (150) is attached to a side wall face (100R) of the cylinder head (33)
on the opposite side to the side wall face (100L) to which the pressing force generation
source (75) is attached.
[0031] The variable valve apparatus for an OHC type internal combustion engine can be further
configured such that
the water pump (150) is disposed on the crankcase side with respect to the pressing
force generation source (75) in the cylinder axial line direction,
an breather chamber (34b) is provided on the inner side of the head cover (34), and
an exit portion (34c) of the breather chamber (34b) is formed on an outer wall face
of the head cover (34) such that an opening thereof is directed to the water pump
(150) side in the vehicle widthwise direction.
[0032] There may further be provided a variable valve apparatus for an OHC type internal
combustion engine which includes a crankcase (31), a cylinder block (32) and a cylinder
head (33) placed in order on the crankcase (31) and fastened together by a plurality
of stud bolts (180) extending through the cylinder block (32) and the cylinder head
(33) in a cylinder axial line direction, a plurality of rocker arms (57, 58) arrayed
and supported for rocking motion in a mutually neighboring relationship on a rocker
arm shaft (55) in the inside of the cylinder head (33) and operable in an interlocking
relationship with engine valves (61, 62), and a head cover (34) placed on the cylinder
head (33) to cover the cylinder head (33), the variable valve apparatus including:
a connection pin (71) fitted for movement in an axial direction of the rocker arm
shaft (55) in the rocker arms (57, 58) positioned adjacent each other and movable
between a connection position at which the connection pin (71) connects the rocker
arms (57,58) positioned adjacent each other to each other for integral rocking motion
and a disconnection position at which the connection pin (71) disconnects the rocker
arms (57, 58) from each other to allow independent rocking motion of each of the rocker
arms (57, 58); and
a push rod (74) interposed between an operating rod (76) of a pressing force generation
source (75) disposed outside the cylinder head (33) and the connection pin (71) and
configured to transmit pressing force of the operating rod (76) to the connection
pin (71) to move the connection pin (71);
the cylinder head (33) having a rod sliding hole (102) formed therein in which the
operating rod (76) and the push rod (74) are fitted coaxially for sliding motion in
a rod axial direction, the cylinder head (33) further having an oil supply hole (130)
formed therein which is open at one end thereof to the inside of the cylinder head
(33) and at the other end thereof to the rod sliding hole (102) and supplies oil therethrough;
the oil supply hole (130) which supplies oil into a sandwiched inner space (80) defined
by and between the operating rod (76) and the push rod (74) in the rod sliding hole
(102) when the pressing force generation source (75) is in an inactive state being
formed at a position offset in the rod axial direction with respect to the sandwiched
inner space (80).
[0033] The variable valve apparatus for an OHC type internal combustion engine as further
described above may be configured such that
the oil supply hole (130) is disposed such that only one of the push rod (74) and
the operating rod (76) faces the oil supply hole (130) when the pressing force generation
source (75) is in an inactive state.
[0034] The variable valve apparatus for an OHC type internal combustion engine as further
described above may be configured such that
part of the sandwiched inner space (80) is communicated with the oil supply hole (130)
when the pressing force generation source (75) is in an inactive state.
[0035] The variable valve apparatus for an OHC type internal combustion engine as further
described above may be configured such that
the oil supply hole (130) and the rod sliding hole (102) have such a positional relationship
that center axial lines thereof cross each other at a right angle and in a spaced
relationship from each other.
[0036] The variable valve apparatus for an OHC type internal combustion engine as further
described above may be configured such that,
stud bolt fastening holes (115, 116, 125, 126) are formed on the cylinder head (33)
such that the stud bolts (180) extend therethrough,
reinforcement plates (140, 141) abutted over an opening end face of at least two of
the stud bolt fastening holes (115, 116, 125, 126) are fastened together with the
cylinder head (33) by the stud bolts (180), and
part of the opening of the oil supply hole (130) on the one end side is covered with
the reinforcement plates (140, 141) as viewed in the cylinder axial direction.
[0037] The variable valve apparatus for an OHC type internal combustion engine as further
described above may be configured such that,
the OHC type internal combustion engine (30) is mounted on a saddle type vehicle (1)
in a posture in which a cylinder axial line (Cc) thereof is tilted forward greatly
to a position proximate to a horizontal position, and
a nut (181) is screwed with the stud bolts (180) which is positioned above the oil
supply hole (130) and is tightened such that an angular portion thereof is directed
downwardly.
[0038] The variable valve apparatus for an OHC type internal combustion engine as further
described above may be configured such that
the oil supply hole (130) is disposed such that the sandwiched inner space (80) when
the pressing force generation source (75) is in an inactive state is placed at a position
at which the sandwiched inner space (80) does not face the oil supply hole (130).
[0039] There may also be provided a variable valve apparatus for an OHC type internal combustion
engine which includes a crankcase (31), a cylinder block (32) and a cylinder head
(33) placed in order on the crankcase (31) and fastened together by a plurality of
stud bolts (180) extending through the cylinder block (32) and the cylinder head (33)
in a cylinder axial line direction, a plurality of rocker arms (57, 58) arrayed and
supported for rocking motion in a mutually neighboring relationship on a rocker arm
shaft (55) in the inside of the cylinder head (33) and operable in an interlocking
relationship with engine valves (61, 62), and a head cover (34) placed on the cylinder
head (33) to cover the cylinder head (33), the variable valve apparatus including:
a connection pin (71) fitted for movement in an axial direction of the rocker arm
shaft (55) in the rocker arms (57, 58) positioned adjacent each other and movable
between a connection position at which the connection pin (71) connects the rocker
arms (57, 58) positioned adjacent each other to each other for integral rocking motion
and a disconnection position at which the connection pin (71) disconnects the rocker
arms (57, 58) from each other to allow independent rocking motion of each of the rocker
arms (57, 58); and
a pressing force transmission member (74, 76) configured to transmit pressing force
of a pressing force generation source (75) disposed outside the cylinder head (33)
to the connection pin (71) to move the connection pin (71);
the connection pin (71) being disposed between rocker arm shaft insertion holes (57h,
58h) in which the rocker arm shaft (55) for the rocker arms (57, 58) is inserted and
action side end portions (57vv, 58vv) which act on the engine valves (61, 62);
the cylinder head (33) having a plurality of stud bolt fastening holes (115, 116,
125,126) formed therein through which the stud bolts (180) extend and rocker arm shaft
supporting holes (112h, 122h) formed therein which support the rocker arm shaft (55),
the cylinder head (33) further having a pressing force transmission member sliding
hole (102) formed therein in which the pressing force transmission member (74, 76)
is inserted for sliding movement, the pressing force transmission member sliding hole
(102) being provided at a position at which the pressing force transmission member
sliding hole (102) overlaps with the rocker arm shaft supporting hole (122h) in the
cylinder axial line direction between the stud bolt fastening hole (125) located nearest
to the rocker arm shaft supporting hole (122h) and the rocker arm shaft supporting
hole (122h).
[0040] The variable valve apparatus for an OHC type internal combustion engine as also described
above may be configured such that
adjustment screws (57t, 58t) for adjusting an abutting position with the engine valves
(61, 62) are screwed in the action side end portions (57vv, 58vv) of the rocker arms
(57, 58), and
an axial line (Cp) of the connection pin (71) is disposed between head side end portions
(57tt, 58tt) of the adjustment screws (57t, 58t) and an axial line (Cr) of the rocker
arm shaft insertion holes (57h, 58h) in the cylinder axial line direction.
[0041] The variable valve apparatus for an OHC type internal combustion engine as also described
above may be configured such that
the connection pin (71) and the pressing force transmission member (74, 76) are provided
on the crankcase (31) side with respect to the mating face (100t) between the cylinder
head (33) and the head cover (34).
[0042] The variable valve apparatus for an OHC type internal combustion engine as also
described above may be configured such that
the pressing force transmission member (74, 76) neighbor with one of the stud bolts
(180).
[0043] The variable valve apparatus for an OHC type internal combustion engine as also described
above may be configured such that,
an axial line (Cd) of the pressing force transmission member (74, 76) is positioned
on the crankcase (31) side with respect to the axial line (Cp) of the connection pin
(71).
[0044] The variable valve apparatus for an OHC type internal combustion engine as also described
above may be configured such that,
the axial line (Cd) of the pressing force transmission member (74, 76) is positioned
on the rocker arm shaft (55) side with respect to the axial line (Cp) of the connection
pin (71).
[0045] The variable valve apparatus for an OHC type internal combustion engine as also described
above may be configured such that
the pressing force generation source (75) is fixedly secured only to the cylinder
head (33).
[Effects of the Invention]
[0046] With the variable valve apparatus for an OHC type internal combustion engine as described
above, the pressing force generation source (75) is attached to the wall face (100L)
of the cylinder head (33) on which the ignition plug (49) is provided in a projecting
manner. Further, the accommodation case (77, 78) which accommodates the main body
of the pressing force generation source (75) therein is provided at the position at
which the accommodation case (77, 78) does not overlap with the ignition plug center
axial line (Cs), which is directed by the ignition plug (49), as viewed in the cylinder
axial line direction. Therefore, the pressing force generation source (75) can be
disposed at the position at which it does not make an obstacle when the ignition plug
(49) is moved to be mounted or dismounted in the axial line direction of the ignition
plug center axial line (Cs) directed by the ignition plug (49) without disposing the
pressing force generation source (75) away from the ignition plug (49). Therefore,
while miniaturization of the cylinder head (33) is achieved, the maintenance performance
of the ignition plug (49) can be maintained favorably.
[0047] With the variable valve apparatus for an OHC type internal combustion engine as described
above, the pressing force generation source (75) is positioned on the head cover (34)
side with respect to the ignition plug (49). Therefore, the maintenance space around
the ignition plug (49) can be assured readily.
[0048] With the variable valve apparatus for an OHC type internal combustion engine as described
above, the pressing force transmission member (74, 76) is provided for sliding movement
on the cylinder head (33). Therefore, swelling of the pressing force generation source
(75), which provides pressing force to the pressing force transmission member (74,
76), to the head cover (34) side can be suppressed. Further, increase in size of the
cylinder head (33) and peripheral elements in the cylinder axial line direction can
be prevented.
[0049] Consequently, the variable valve apparatus can be made suitable particularly for
a saddle type vehicle for which miniaturization of the cylinder head (33) and peripheral
elements is demanded.
[0050] With the variable valve apparatus for an OHC type internal combustion engine as described
above, the pressing force generation source (75) has the plural attachment arm portions
(77pr, 77qr, 77rr) formed around the accommodation case (77, 78) so as to extend radially
along the wall face (100L) of the cylinder head (33). Further, the attachment arm
portions (77pr, 77qr, 77rr) are attached only to the cylinder head (33). Therefore,
it is possible to raise the rigidity of the cylinder head (33) and further suppress
swelling of the pressing force generation source (75) to the head cover (34) side.
[0051] Further, the electromagnetic solenoid (75) is attached only to the cylinder head
(33) but not to the head cover (34). Therefore, upon maintenance of the valve system
in the cylinder head (33), the head cover (34) can be removed without removing the
pressing force generation source (75). Consequently, maintenance operation of the
valve system can be carried out readily.
[0052] With the variable valve apparatus for an OHC type internal combustion engine as described
above, from among the attachment arm portions (77pr, 77qr, 77rr), the attachment arm
portion (77pr) which extends in the direction overlapping with the ignition plug center
axial line (Cs) as viewed in the cylinder axial line direction has the recessed portion
(77d) formed thereon so as to be open toward the ignition plug (49) side in such a
manner that the recessed portion (77d) crosses but keeps away from the ignition plug
center axial line (Cs). Therefore, when the ignition plug (49) is moved in the direction
of the ignition plug center axial line (Cs) to mount or dismount the ignition plug
(49), the attachment arm portion (77pr) does not make an obstacle thanks to the recessed
portion (77d). Consequently, a good maintenance performance of the ignition plug (49)
can be maintained favorably.
[0053] With the variable valve apparatus for an OHC type internal combustion engine as described
above, on the cylinder head (33), the rib portions (103pr, 103qr, 103rr) with which
the attachment arm portions (77pr, 77qr, 77rr) extending from the periphery of the
accommodation case (77, 78) are abutted and the attachment boss portions (103p, 103q,
103r) at the end portions of the rib portions (103pr, 103qr, 103rr) are formed in
a projecting manner, and the attachment arm portions (77pr, 77qr, 77rr) are attached
to the attachment boss portions (103p, 103q, 103r). Therefore, the pressing force
generation source (75) is retained stably on the cylinder head (33) by the rib portions
(103pr, 103qr, 103rr) and the attachment boss portions (103p, 103q, 103r).
[0054] Further, the attachment arm portions (77pr, 77qr, 77rr) of the pressing force generation
source (75) are abutted with and attached to the rib portions (103pr, 103qr, 103rr)
and the attachment boss portions (103p, 103q, 103r). Therefore, the rib portions (103pr,
103qr, 103rr) and the attachment boss portions (103p, 103q, 103r) can be maintained
in a high rigidity state. Consequently, the pressing force generation source (75)
can be supported further firmly.
[0055] With the variable valve apparatus for an OHC type internal combustion engine as described
above, the accommodation case (77, 78) and the attachment arm portions (77pr, 77qr,
77rr) of the pressing force generation source (75) are made of a metal. Therefore,
heat generated in the accommodation case (77, 78) for the pressing force generation
source (75) can be transmitted from the attachment arm portions (77pr, 77qr, 77rr)
to the rib portions (103pr, 103qr, 103rr). Consequently, the heat radiation efficiency
of the pressing force generation source (75) can be improved.
[0056] Further, the rib portions (103pr, 103qr, 103rr) and the attachment boss portions
(103p, 103q, 103r) are formed in a projecting manner on the wall face (100L) of the
cylinder head (33). Therefore, those portions of the attachment arm portions (77pr,
77qr, 77rr) abutted by the rib portions (103pr, 103qr, 103rr) and attachment boss
portions (103p, 103q, 103r) which protrude from the abutting face cooperate with the
cylinder head wall face (100L) to form the space therebetween. As running wind enters
the space, the attachment arm portions (77pr, 77qr, 77rr) can be cooled, and consequently,
the cooling effect can be raised.
[0057] With the variable valve apparatus for an OHC type internal combustion engine as described
above, on the wall face (100L) to which the pressing force generation source (75)
of the cylinder head (33) is attached, the oil passage (133) is formed in the proximity
of the pressing force generation source (75). Therefore, the pressing force generation
source (75) can be cooled effectively by oil flowing in the oil passage (133).
[0058] With the variable valve apparatus for an OHC type internal combustion engine as described
above, the OHC type internal combustion engine (30) is mounted on the vehicle body
frame of the saddle type vehicle (1) in a posture in which the cylinder axial line
(Cc) is tilted forward greatly to the position proximate to the horizontal position.
Further, the pressing force generation source (75) is attached to the side wall face
(100L) of the cylinder head (33) directed in the vehicle widthwise direction, and
the pressing force generation source (75) is covered on the outer sides thereof in
the vehicle widthwise direction with part (6) of the vehicle body frame. Therefore,
the pressing force generation source (75) is disposed between the cylinder head (33)
and the vehicle body frame (6). Consequently, the pressing force generation source
(75) can be protected effectively from an external factor by the cylinder head (33)
and the vehicle body frame (6).
[0059] With the variable valve apparatus for an OHC type internal combustion engine as described
above, the water pump (150) is attached to the side wall face (100R) of the cylinder
head (33) on the opposite side to the side wall face (100L) to which the pressing
force generation source (75) is attached. Therefore, the pressing force generation
source (75) and the water pump (150) which are heavy articles are attached in a distributed
manner on the opposite side wall faces (100L, 100R) directed in the vehicle widthwise
direction of the cylinder head (33) so that they do not interfere with each other.
Consequently, the weight balance around the cylinder head (33) can be improved. Further,
also where both of the pressing force generation source (75) and the water pump (150)
are attached to the cylinder head (33), the maintenance performance of the ignition
plug (49) can be assured favorably.
[0060] With the variable valve apparatus for an OHC type internal combustion engine as described
above, the breather chamber (34b) is provided on the inner side of the head cover
(34). Further, the exit portion (34c) of the breather chamber (34b) is formed on the
outer wall face of the head cover (34) such that the opening thereof is directed to
the water pump (150) side in the vehicle widthwise direction. Therefore, the breather
hose (146) connected to the exit portion (34c) of the breather chamber (34b) of the
head cover (34) and extending to the water pump (150) side does not interfere with
the pressing force generation source (75) on the opposite side. Also it can be avoided
readily for the breather hose (146) to interfere with the water pump (150) provided
on the crankcase (31) side with respect to the pressing force generation source (75).
[0061] With the variable valve apparatus for an OHC type internal combustion engine as further
described above, the oil supply hole (130) which supplies oil into the sandwiched
inner space (80) defined by and between the operating rod (76) and the push rod (74)
in the rod sliding hole (102) when the pressing force generation source (75) is in
an inactive state is formed at the position offset in the rod axial direction with
respect to the sandwiched inner space (80). Therefore, when the pressing force generation
source (75) is in an inactive state, the sandwiched inner space (80) at the position
at which the oil supply hole (130) is offset in the axial direction can be made similar
to a closed space. Further, at an initial stage when the pressing force generation
source (75) is rendered operative to start movement of the operating rod (76), the
oil supplied into the sandwiched inner space (80) having a state close to a closed
space is less likely to flow out from the oil supply hole (130). Therefore, the oil
in the sandwiched inner space (80) can enhance the damper function as an oil damper.
[0062] Further, together with the movement of the operating rod (76), also the sandwiched
inner space (80) moves and the offset from the oil supply hole (130) decreases. Therefore,
the oil in the sandwiched inner space (80) gradually flows out from the oil supply
hole (130).
[0063] Accordingly, even if the operating rod (76) is abutted with the push rod (74) soon,
since also the push rod (74) is moving upon such abutment, an impact by the abutment
can be suppressed to a very low level.
[0064] Moreover, with the variable valve apparatus for an OHC type internal combustion engine
as further described above, the oil supply hole (130) is disposed such that only one
of the push rod (74) and the operating rod (76) faces the oil supply hole (130) when
the pressing force generation source (75) is in an inactive state. Therefore, a communication
port on the boundary between the oil supply hole (130) and the rod sliding hole (102)
is partly or fully closed with the push rod (74) or the operating rod (76). Consequently,
the sandwiched inner space (80) formed between the operating rod (76) and the push
rod (74) in the rod sliding hole (102) can be made similar to a closed space further.
Therefore, flowing out of oil in the sandwiched inner space (80) at an initial stage
when the pressing force generation source (75) is rendered operative can be suppressed
to further enhance the oil damper function.
[0065] With the variable valve apparatus for an OHC type internal combustion engine as further
described above, part of the sandwiched inner space (80) is communicated with the
oil supply hole (130) when the pressing force generation source (75) is in an inactive
state. Therefore, when the pressing force generating source (75) is in an inactive
state, oil can be supplied from the oil supply hole (130) into the sandwiched inner
space (80) to fill the sandwiched inner space (80). Further, since the connection
port which communicates the sandwiched inner space (80) and the oil supply hole (130)
with each other therethrough is narrow, the sandwiched inner space (80) can be kept
in a state proximate to that of a closed space. Consequently, flowing out of oil in
the sandwiched inner space (80) at an initial stage when the pressing force generation
source (75) is rendered operative can be suppressed to assure a high oil damper function.
[0066] With the variable valve apparatus for an OHC type internal combustion engine as further
described above, the oil supply hole (130) and the rod sliding hole (102) have such
a positional relationship that the center axial lines thereof cross each other at
a right angle and in a spaced relationship from each other. Therefore, the communication
port on the boundary between the oil supply hole (130) and the rod sliding hold (102)
is formed narrower. Further, the oil supply hole (130) is offset not only in the axial
direction but also in a perpendicular direction to the axial direction with respect
to the sandwiched inner space (80). Therefore, while the pressing force generation
source (75) is rendered operative to start movement of the operating rod (76) until
the end of the operating rod (76) passes the oil supply hole (130), the sandwiched
inner space (80) can be kept in a state proximate to that of a closed state. Consequently,
flowing out of the oil in the sandwiched inner space (80) can be suppressed further
to assure a high oil damper function.
[0067] With the variable valve apparatus for an OHC type internal combustion engine as further
described above, the reinforcement plates (140, 141) abutted over the opening end
face of at least two of the stud bolt fastening holes (115, 116, 125, 126) are fastened
together with the cylinder head (33) by the stud bolts (180). Therefore, the rigidity
of the cylinder head (33) can be kept high. Further, part of the opening of the oil
supply hole (130) is covered with the reinforcement plates (140, 141) as viewed in
the cylinder axial direction. Therefore, flowing out of the oil in the sandwiched
inner space (80) when the pressing force generation source (75) operates is suppressed,
and consequently, the oil damper function can be maintained high more and more.
[0068] With the variable valve apparatus for an OHC type internal combustion engine as further
described above, the OHC type internal combustion engine (30) is mounted on the saddle
type vehicle (1) in the posture in which the cylinder axial line (Cc) thereof is tilted
forward greatly to a position proximate to a horizontal position. Further, the nut
(181) is screwed with the stud bolts (180) which is positioned above the oil supply
hole (130) and is tightened such that the angular portion thereof is directed downwardly.
Therefore, oil sticking to the nut (181) flows downwardly from the angular portion.
Therefore, the oil is guided to and enters the oil supply hole (130) readily.
[0069] With the variable valve apparatus for an OHC type internal combustion engine as further
described above, the oil supply hole (130) is disposed such that the sandwiched inner
space (80) when the pressing force generation source (75) is in an inactive state
is placed at the position at which the sandwiched inner space (80) does not face the
oil supply hole (130). Therefore, the sandwiched inner space (80) when the pressing
force generation source (75) is in an inactive state is a closed space. Further, flowing
out of the oil in the sandwiched inner space (80) at an initial stage when the pressing
force generation source (75) is rendered operative is very little. Consequently, the
high oil damper function can be operated effectively.
[0070] Further, when the state of the pressing force generation source (75) changes over
from an active state to an inactive state, the push rod (74) is retracted together
with the operating rod (76). Thereupon, the sandwiched inner space (80) between the
push rod (74) and the operating rod (76) is expanded while passing the oil supply
hole (130). Consequently, the oil can be sucked from the oil supply hole (130) into
the sandwiched inner space (80) to fill the sandwiched inner space (80) with the oil
readily.
[0071] With the variable valve apparatus for an OHC type internal combustion engine as also
described above, the connection pin (71) is disposed between the rocker arm shaft
insertion holes (57h, 58h) for the rocker arms (57, 58) and the action side end portions
(57vv, 58vv) which act on the engine valves (61, 62). Therefore, the connection pin
(71) can be provided not at a position swollen by a great amount to the head cover
(34) side from the rocker arm shaft (55) but at a position nearer to the rocker arm
shaft (55) in the cylinder axial line direction on the crankcase (31) side. Therefore,
there is no necessity to make the rocker arms (57, 58) themselves swell to the head
cover (34) side to increase the size of them. In addition, increase in size of the
cylinder head (33) and the head cover (34) can be avoided.
[0072] Further, the pressing force transmission member sliding hole (102) is formed on the
cylinder head (33) at the position at which it overlaps with the rocker arm shaft
supporting hole (122h) in the cylinder axial line direction between the stud bolt
fastening hole (125) and the rocker arm shaft supporting hole (122h). Therefore, the
pressing force transmission member (74, 76) can be disposed compactly making use of
the space between the stud bolt fastening hole (125) and the rocker arm shaft supporting
hole (122h). Further, the pressing force transmission member (74, 76) is provided
at the position at which it overlaps with the rocker arm shaft (55) in the cylinder
axial line direction. Therefore, the cylinder head (33) can be miniaturized in the
cylinder axial line direction, and increase in size of the cylinder head (33) and
the head cover (34) can be avoided more and more.
[0073] Specifically, as an OHC type internal combustion engine to be incorporated in a saddle
type vehicle in which it is difficult to assure a space, the OHC type internal combustion
engine of the present invention which avoids increase in size of the cylinder head
and associated elements can be suitably applied.
[0074] With the variable valve apparatus for an OHC type internal combustion engine as also
described above, the adjustment screws (57t, 58t) for adjusting the abutting position
with the engine valves (61, 62) are screwed in the action side end portions (57vv,
58vv) of the rocker arms (57, 58). Further, the axial line (Cp) of the connection
pin (71) is disposed between the head side end portions (57tt, 58tt) of the adjustment
screws (57t, 58t) and the axial line (Cr) of the rocker arm shaft insertion holes
(57h, 58h) in the cylinder axial line direction. Therefore, the rocker arm shaft (55),
connection pin 71 and adjustment screws (57t, 58t) can be juxtaposed on a substantially
straight line. Consequently, the valve side arm portions (57v, 58v) of the rocker
arms (57, 58) from the rocker arm shaft insertion holes (57h, 58h) to the action side
end portions (57vv, 58vv) which act on the engine valves (61, 62) can be formed in
a substantially liner shape. Therefore, the rocker arms (57, 58) can be miniaturized
in a high space efficiency.
[0075] Further, the portions of the rocker arms (57, 58) in which the connection pin (71)
is fitted for movement are formed with a thickness increased by an amount by which
the connection pin (71) is fitted and supported. Therefore, the rigidity of the valve
side arm portions (57v, 58v) from the rocker arm shaft insertion holes (57h, 58h)
to the action side end portions (57vv, 58vv) which act on the engine valves (61, 62)
can be raised.
[0076] With the variable valve apparatus for an OHC type internal combustion engine as also
described above, the connection pin (71) and the pressing force transmission member
(74, 76) are provided on the crankcase (31) side with respect to the mating face (100t)
between the cylinder head (33) and the head cover (34). Therefore, when the rocker
arm shaft (55), connection pin (71) and adjustment screws (57t, 58t) are juxtaposed
on a straight line, the adjustment screws (57t, 58t) are positioned in the proximity
of the mating face (100t) between the cylinder head (33) and the head cover (34).
Consequently, an adjustment operation of the adjustment screws (57t, 58t) can be carried
out readily.
[0077] Especially, the connection pin (71) and the pressing force transmission members (74,
76) are positioned on the crankcase (31) side with respect to the head side end portions
(57tt, 58tt) of the adjustment screws (57t, 58t). Therefore, an adjustment operation
by the adjustment screws (57t, 58t) can be carried out more readily.
[0078] With the variable valve apparatus for an OHC type internal combustion engine as
also described above, the pressing force transmission member (74, 76) neighbor with
one of the stud bolts (180). Therefore, the stud bolt fastening hole (125) and the
pressing force transmission member sliding hole (102) of the cylinder head (33) can
be positioned as near as possible to the rocker arm shaft supporting hole (122h).
Consequently, miniaturization of the cylinder head (33) can be anticipated.
[0079] With the variable valve apparatus for an OHC type internal combustion engine as also
described above, the axial line (Cd) of the pressing force transmission member (74,
76) is positioned on the crankcase (31) side with respect to the axial line (Cp) of
the connection pin (71). Therefore, the pressing force generation source (75) which
presses the pressing force transmission member (74, 76) can be disposed near to the
crankcase (31) side. Consequently, the swelling amount of the pressing force generation
source (75) to the head cover (34) side in the cylinder axial line direction can be
reduced.
[0080] With the variable valve apparatus for an OHC type internal combustion engine as also
described above, the axial line (Cd) of the pressing force transmission member (74,
76) is positioned on the rocker arm shaft (55) side with respect to the axial line
(Cp) of the connection pin (71). Therefore, a configuration wherein, while the pressing
force transmission member (74, 76) avoids interference with the stud bolts (180),
it presses the connection pin (71) efficiently can be implemented.
[0081] With the variable valve apparatus for an OHC type internal combustion engine as also
described above, the pressing force generation source (75) is fixedly secured only
to the cylinder head (33). Therefore, the shape of the mating face between the cylinder
head (33) and the head cover (34) can be simplified. Besides, since the necessity
to fix the pressing force generation source (75) to the head cover (34) side is eliminated,
also simplification of the head cover (34) can be achieved.
[Brief Description of the Drawings]
[0082]
FIG. 1 is a general side elevational view of a scooter type motorcycle according to
an embodiment of the present invention.
FIG. 2 is a view as viewed in a direction indicated by an arrow mark II of FIG. 1.
FIG. 3 is a general left side elevational view of a power unit.
FIG. 4 is a right side elevational view of the power unit with part of an internal
combustion engine omitted.
FIG. 5 is a sectional view of the internal combustion engine (sectional view taken
along line V-V of FIG. 3).
FIG. 6 is a vertical sectional view of a cylinder head and peripheral elements of
the same.
FIG. 7 is a view of a cylinder head and a valve mechanism as viewed in a direction
of an axial line of a cylinder from a head cover side with the head cover removed.
FIG. 8 is a sectional view taken along line VIII-VIII of FIGS. 6 and 7.
FIG. 9 is a sectional view taken along line IX-IX of FIGS. 6 and 7.
FIG. 10 is a partial sectional view of the cylinder head and a variable valve apparatus
when an electromagnetic solenoid is inactive (sectional view taken along line X-X
of FIG. 6).
FIG. 11 is a partial sectional view of the electromagnetic solenoid in an active state.
FIG. 12 is a partial sectional view of the cylinder head and the variable valve apparatus
when the electromagnetic solenoid is inactive in a different example.
FIG. 13 is a top plan view of the cylinder head.
FIG. 14 is a left side elevational view of the cylinder head itself (view as viewed
in a direction indicated by an arrow mark XIV of FIG. 13).
FIG. 15 is a right side elevational view of the cylinder head itself (view as viewed
in a direction indicated by an arrow mark XV of FIG. 13).
FIG. 16 is a sectional view taken along line XVI-XVI of FIG. 13.
FIG. 17 is a sectional view taken along line XVII-XVII of FIG. 14.
FIG. 18 is a sectional view taken along line XVIII-XVIII of FIGS. 13 and 17.
[Mode for Carrying Out the Invention]
[0083] In the following, an embodiment according to the present invention is described with
reference to the drawings.
[0084] FIG. 1 is a side elevational view of a scooter type motorcycle 1 which is a saddle
type vehicle according to an embodiment to which the present invention is applied.
[0085] In the present specification, the forward, rearward, leftward and rightward directions
are determined with reference the vehicle of the motorcycle 1.
[0086] A vehicle body front section if and a vehicle body rear section 1r are connected
to each other by a low floor section 1c. In a vehicle body frame which configures
a skeleton of a vehicle body, a down tube 3 extends downwardly from a head pipe 2
of the vehicle body front section if. A pair of floor pipes 4 branching to the left
and the right at a lower end of the down tube 3 are curved horizontally and extend
rearwardly below the floor section 1c. The floor pipes 4 are bent obliquely upwardly
at a rear location of the floor section 1c and rise and extend rearwardly. A pair
of left and right main pipes 5 are supported at a front portion thereof by rear ends
of the floor pipes 4 and extend obliquely upwardly rearwardly. The left and right
main pipes 5 are connected at rear ends thereof to each other.
[0087] A connection pipe 6 is fixedly secured at the opposite end portions thereof to and
provided in a projecting manner at rear portions of the floor pipes 4 which are erected
obliquely upwardly. The connection pipe 6 is bent in a channel shape in a forward
direction.
[0088] The main pipes 5 are fixedly secured at an end thereof to left and right side portions
of the connection pipe 6 to connect the main pipes 5, floor pipes 4 and connection
pipe 6 to each other to assemble them firmly (refer to FIG. 2).
[0089] An accommodation box 8 and a fuel tank 9 are supported forwardly and backwardly by
the main pipes 5, and a seat 10 is disposed above them.
[0090] On the vehicle body front section if, a handlebar 11 is supported for pivotal motion
on the head pipe 2 and provided at an upper location. A front fork 12 extends downwardly,
and a front wheel 13 is supported for rotation at a lower end of the front fork 12.
[0091] Brackets 7 are provided in a downwardly projecting manner at the rear upwardly extending
portions of the floor pipes 4. A power unit 20 is connected to and supported for rocking
motion on the brackets 7 through a link member 16.
[0092] The power unit 20 is, at a front portion thereof, a single cylinder four-stroke water-cooled
OHC type internal combustion engine 30 and has a posture in which a cylinder axial
line of a cylinder is tilted forward greatly to a position substantially proximate
to a horizontal position. A hanger bracket 18 projects forwardly from a lower end
of a crankcase 31 of the internal combustion engine 30 and is connected at an end
portion thereof to the link member 16 through a pivot shaft 19.
[0093] The power unit 20 includes a belt-type continuously variable transmission 21 extending
rearwardly from the internal combustion engine 30. A reduction mechanism 22 is provided
at a rear portion of the belt-type continuously variable transmission 21. A rear wheel
14 is provided on a rear wheel axle 14a which is an output power shaft of the reduction
mechanism 22.
[0094] A bracket 20b is provided uprightly at a rear portion of the power unit 20 at which
the reduction mechanism 22 is provided. A bracket 5b is provided in a projecting manner
at a rear portion of the main pipes 5. A rear cushion 15 is interposed between the
bracket 20b and the bracket 5b.
[0095] Referring to FIG. 3 which is a side elevational view of the power unit 20, the internal
combustion engine 30 includes a cylinder block 32, a cylinder head 33 and a head cover
34 placed in order substantially in front of the crankcase 31 and is tilted forward
greatly. At an upper portion of the power unit 20, an intake pipe 23 extends from
an upper portion of the cylinder head 33, which is tilted forward greatly, of the
internal combustion engine 30 and is bent rearwardly. A throttle body 25 is positioned
above the cylinder block 32 and connected to the intake pipe 23. An air cleaner 27
is connected to the throttle body 25 through a connection pipe 26 and positioned above
the belt-type continuously variable transmission 21.
[0096] It is to be noted that an injector 24 is mounted on the intake pipe 23 and injects
fuel toward an intake port.
[0097] Meanwhile, an exhaust pipe 28 extends downwardly from a lower portion of the cylinder
head 33 and is bent rearwardly. Further, the exhaust pipe 28 extends rearwardly in
a rightwardly displaced state until it is connected to a muffler (not shown) on the
right side of the rear wheel 14.
[0098] The vehicle body front section if is covered from the front and the rear with a front
cover 29a and a leg shield 29b, respectively, and is covered at a lower portion from
the front to the left and right sides thereof with a front lower cover 29c. The floor
section 1c is covered with a side cover 29d and the vehicle body rear section 1r is
covered from the left and right sides with a body cover 29e.
[0099] FIG. 5 is a sectional view of the internal combustion engine 30 of the front half
of the power unit 20 (sectional view taken along line V-V of FIG. 3).
[0100] The internal combustion engine 30 includes a piston 36 which moves back and forth
in a cylinder liner 38 of the cylinder block 32, and a crankshaft 35. The piston 36
and a crankpin 35a of the crankshaft 35 are connected to each other by a connecting
rod 37.
[0101] The crankcase 31 is configured from leftwardly and rightwardly split left crankcase
31L and right crankcase 31R united together. The right crankcase 31R forms a half
body of the crankcase section. Meanwhile, the left crankcase 31L forms, at a front
portion thereof, a half body of the crankcase section and is swollen rearwardly so
that it serves also as a transmission case in which the belt-type continuously variable
transmission 21 elongated forwardly and backwardly is accommodated.
[0102] The left crankcase (transmission case) 31L is covered at a forwardly and backwardly
elongated left side open face thereof with a transmission case cover 40 and has the
belt-type continuously variable transmission 21 accommodated therein.
[0103] In the crankcase formed from the front portion of the left crankcase 31L and the
right crankcase 31R united together, the crankshaft 35 is supported for rotation by
left and right main bearings 39. The crankshaft 35 has left and right extensions extending
in a horizontal direction to the left and the right. A centrifugal weight 41 of the
belt-type continuously variable transmission 21 and a driving pulley 42a are provided
on the left extension of the crankshaft 35.
[0104] Referring to FIG. 3, the belt-type continuously variable transmission 21 includes
a V belt 42c extending between and around the driving pulley 42a and a driven pulley
42b provided on an input shaft 22a of the reduction mechanism 22 to transmit power.
The transmission ratio of the belt-type continuously variable transmission 21 is automatically
changed by a change in winding diameter of the V belt 42c on the driving pulley 42a
by the centrifugal weight 41 and a simultaneous change in winding diameter on the
driven pulley 42b thereby to vary the speed continuously. It is to be noted that the
centrifugal weight 41 moves in response to the rotational speed of the engine.
[0105] A cam chain driving sprocket wheel 43 and so forth are mounted on the right extension
of the crankshaft 35. An AC generator 44 is provided at a right end portion of the
right extension.
[0106] A plurality of radiator fans 45 are formed on a right side face of an outer rotor
44r of the AC generator 44.
[0107] An outer periphery of the radiator fans 45 is generally surrounded by a shroud 46.
A radiator 47 is supported on the shroud 46 closely on the right side of a radiator
fan 45. The radiator 47 is covered with a radiator cover 48 with a louver.
[0108] The present internal combustion engine 30 adopts a four-valve system of the SOHC
type. The cylinder block 32 and the cylinder head 33 are fastened to the crankcase
31 by four stud bolts 180 extending therethrough in a cylinder axial line Cc (center
axis of the cylinder bore) direction. A valve mechanism 50 is provided in the cylinder
head 33 (refer to FIGS. 5 and 6).
[0109] It is to be noted that the head cover 34 is placed on and covers a mating face 100t
of the cylinder head 33 with an elastic seal member 185 interposed therebetween in
such a manner as to cover the valve mechanism 50.
[0110] A cam chain 51 extends between and around a camshaft 54 and the crankshaft 35 and
carries out power transmission to the valve mechanism 50 in the head cover 34. A cam
chain chamber 52 for the cam chain 51 is provided in a communicating relationship
with the right crankcase 31R, cylinder block 32 and cylinder head 33 (refer to FIG.
5).
[0111] In particular, a driven cam chain sprocket wheel 53 is fitted on a right end of the
camshaft 54 directed in the leftward and rightward horizontal direction, and the driving
cam chain sprocket wheel 43 is fitted on the crankshaft 35. The cam chain 51 extends
through the inside of the cam chain chamber 52 between and around the driven cam chain
sprocket wheel 53 and the driving cam chain sprocket wheel 43.
[0112] Meanwhile, an ignition plug 49 is inserted in the cylinder head 33 from the opposite
side (left side) to the cam chain chamber 52 toward a combustion chamber 90 (refer
to FIGS. 2 and 5).
[0113] Referring to FIGS. 6 and 10, two left and right first and second intake ports 91
and 92 extend upwardly from the combustion chamber 90 which the top face of the piston
36 of the cylinder head 33, which is tilted forward greatly, faces. The first and
second intake ports 91 and 92 intermediately merge with each other into a single upstream
side intake port 93. The upstream side intake port 93 is connected to the intake pipe
23.
[0114] On the other hand, two left and right first and second exhaust ports 95 and 96 extend
downwardly from the combustion chamber 90. The first and second exhaust ports 95 and
96 intermediately merge with each other into a single downstream side exhaust port
97. The downstream side exhaust port 97 is connected to the exhaust pipe 28.
[0115] Cylindrical valve guides 61g and 62g are fitted integrally with curved outer wall
portions of the first and second intake ports 91 and 92 of the cylinder head 33, respectively.
A first intake valve 61 and a second intake valve 62 are supported for sliding movement
on the valve guides 61g and 62g and open and close openings of the first and second
intake ports 91 and 92 which face the combustion chamber 90, respectively.
[0116] Meanwhile, valve guides 63g and 64g are fitted integrally with curved outer wall
portions of the first and second exhaust ports 95 and 96 of the cylinder head 33,
respectively. A first exhaust valve 63 and a second exhaust valve 64 are supported
for sliding movement on the valve guides 63g and 64g and open and close openings of
the first and second exhaust ports 95 and 96 which face the combustion chamber 90,
respectively.
[0117] The first and second intake valves 61 and 62 and the first and second exhaust valves
63 and 64 are biased upwardly by valve springs 61s, 62s and 63s, 64s, respectively,
so that they close the openings which face the combustion chamber 90.
[0118] The valve mechanism 50 has the cylinder axial line Cc tilted forward greatly to a
position proximate to a horizontal position. Therefore, the first and second intake
valves 61 and 62 which open and close the openings of the first and second intake
ports 91 and 92 which face the combustion chamber 90, respectively, are disposed above
the camshaft 54. Meanwhile, the first and second exhaust valves 63 and 64 which open
and close the openings of the first and second exhaust ports 95 and 96 which face
the combustion chamber 90, respectively, are disposed below the camshaft 54.
[0119] As shown in FIG. 6, an intake rocker arm shaft 55 and an exhaust rocker arm shaft
56 are disposed at obliquely upper and lower positions in front of the camshaft 54,
respectively.
[0120] Referring to FIGS. 6 and 7, a first intake rocker arm 57 and a second intake rocker
arm 58 are supported in a leftwardly and rightwardly adjacent relationship to each
other for rocking motion on the intake rocker arm shaft 55 on the upper side. Meanwhile,
an exhaust rocker arm 59 is supported for rocking motion on the exhaust rocker arm
shaft 56 on the lower side.
[0121] The first intake rocker arm 57 has a cam side arm portion 57c extending downwardly
from a pivotally supporting portion 57a thereof and a roller 57r supported for rotation
at a lower end of the cam side arm portion 57c. The first intake rocker arm 57 rolling
contacts at the roller 57r thereof with a first intake cam lobe 54i of the camshaft
54. The first intake rocker arm 57 further has a valve side arm portion 57v extending
upwardly from the pivotally supporting portion 57a thereof and an adjustment screw
57t screwed at an action end 57vv which is an upper end portion of the valve side
arm portion 57v. The first intake rocker arm 57 contacts at the adjustment screw 57t
thereof with an upper end of a valve stem of the first intake valve 61 which is biased
upwardly by the valve spring 61s.
[0122] The second intake rocker arm 58 has a cam side arm portion 58c extending downwardly
from a portion thereof offset to the left side from a pivotally supporting portion
58a along the first intake rocker arm 57. The second intake rocker arm 58 further
has a slipper 58s formed at a lower portion of the cam side arm portion 58c. The second
intake rocker arm 58 sliding contacts at the slipper 58s thereof with a second intake
cam lobe 54ii of the camshaft 54. The second intake rocker arm 58 further has a valve
side arm portion 58v extending upwardly from the pivotally supporting portion 58a
thereof and an adjustment screw 58t screwed at an action end portion 58vv which is
an upper end portion of the valve side arm portion 58v. The second intake rocker arm
58 contacts at the adjustment screw 58t thereof with an upper end of a valve stem
of the second intake valve 62 which is biased upwardly by the valve spring 62s.
[0123] The exhaust rocker arm 59 supported for rocking motion on the exhaust rocker arm
shaft 56 on the lower side has a cylindrical pivotally supporting portion 59a positioned
below the first intake rocker arm 57 and the second intake rocker arm 58. The exhaust
rocker arm 59 further has a cam side arm portion 59c extending upwardly from a portion
thereof offset to the right side of the pivotally supporting portion 59a and a roller
59r supported for rotation at an upper end of the cam side arm portion 59c. The exhaust
rocker arm 59 rolling contacts at the roller 59r thereof with an exhaust cam lobe
54e of the camshaft 54. The exhaust rocker arm 59 further has valve side arm portions
59v and 59vv extending downwardly from the opposite left and right sides of the pivotally
supporting portion 59a thereof and adjustment screws 59t and 59tt screwed at lower
ends of the valve side arm portions 59v and 59vv, respectively. The exhaust rocker
arm 59 contacts at the adjustment screws 59t and 59tt thereof with an upper end of
a valve stem of the first and second exhaust valves 63 and 64 which are biased upwardly
by the valve springs 63s and 64s, respectively.
[0124] Referring to FIG. 8, the first intake cam lobe 54i of the camshaft 54 moves, by a
cam profile thereof, the roller 57r of the first intake rocker arm 57 forwardly at
a predetermined rotational angle of the camshaft 54 to rock the first intake rocker
arm 57. Consequently, the adjustment screw 57t at the other end of the first intake
rocker arm 57 pushes the first intake valve 61 against the valve spring 61s to open
the opening of the first intake port 91, which faces the combustion chamber 90, at
a predetermined timing.
[0125] Similarly, the exhaust cam lobe 54e moves, by a cam profile thereof, the roller 59r
of the exhaust rocker arm 59 forwardly at a predetermined rotational angle of the
camshaft 54 to rock the exhaust rocker arm 59. Consequently, the adjustment screws
59t and 59tt at the other end of the exhaust rocker arm 59 push the exhaust valves
63 and 64 against the valve springs 63s and 64s to open the openings of the first
and second exhaust ports 95 and 96 which face the combustion chamber 90 at a predetermined
timing, respectively.
[0126] However, if the second intake cam lobe 54ii has an outer peripheral face of a substantially
cylindrical shape and the slipper 58s at the one end of the second intake rocker arm
58 is in sliding contact with the second intake cam lobe 54ii, then the second intake
rocker arm 58 is little rocked. Consequently, the second intake valve 62 is placed
in a closed inactive state in which the opening of the second intake port 92 which
faces the combustion chamber 90 remains closed.
[0127] However, in order to prevent occurrence of stagnation of fuel in the closed inactive
state of the valve, the second intake cam lobe 54ii has a very small cam protrusion
at a rotational angle thereof same as that of the first intake cam lobe 54i so that
the second intake valve 62 is opened a little.
[0128] Accordingly, the closed inactive state of the valves in the present embodiment is
not a fully closed rest state of the valve but involves a very small amount of opening
of the valve.
[0129] It is to be noted that the second intake valve 62 is placed in a closed inactive
state except when it is driven to open and close at timings same as those of the first
intake valve 61 when the second intake rocker arm 58 is connected for integral rocking
motion to the first intake rocker arm 57 by a variable valve apparatus 70.
[0130] In the following, the variable valve apparatus 70 is described with reference to
FIG. 10.
[0131] It is to be noted that FIG. 10 is a partial sectional view of the cylinder head 33
and the variable valve apparatus 70 as viewed in a direction of the cylinder axial
line from the head cover side, and the leftward and rightward relationship of them
is reverse to that when the figure is viewed.
[0132] Referring to FIG. 10, the first intake rocker arm 57 and the second intake rocker
arm 58 extend through rocker arm shaft insertion holes 57h and 58h formed in the intake
rocker arm shaft 55 and are supported adjacent each other in the leftward and rightward
direction for rocking motion on the intake rocker arm shaft 55. The first intake rocker
arm 57 and the second intake rocker arm 58 have the valve side arm portions 57v and
58v and a first guide hole 57gh and a second guide hole 58gh, respectively. The valve
side arm portions 57v and 58v extend upwardly from the pivotally supporting portions
57a and 58a thereof. The first guide hole 57gh and the second guide hole 58gh are
perforated in parallel to the intake rocker arm shaft 55 in the valve side arm portions
57v and 58v, respectively. The first guide hole 57gh and the second guide hole 58gh
are formed as circular holes of an equal diameter and connected in a leftwardly and
rightwardly contiguous state to and coaxially with each other when the first intake
valve 61 and the second intake valve 62 are in the closed state, respectively.
[0133] It is to be noted that the first guide hole 57gh and the second guide hole 58gh have
bottom walls 57g and 58g formed on the opposite sides to the faces thereof which communicate
with each other and the bottom wall 57g of the first guide hole 57gh has a circular
hole at the center thereof.
[0134] A connection pin 71 is fitted for sliding movement in the leftward and rightward
axial direction in the first guide hole 57gh. In the second guide hole 58gh, a disconnection
piston 72 of a bottomed cylindrical shape is fitted for sliding movement in the leftward
and rightward axial direction with a spring 73 interposed between the disconnection
piston 72 and the bottom wall 58g.
[0135] The connection pin 71 is configured from a cylindrical main body 71a fitted fully
in the first guide hole 57gh and a rod portion 71b projecting from the center of a
left end face of the cylindrical main body 71a and extending through the hollow hole
of the bottom wall 57g. When the first guide hole 57gh and the second guide hole 58gh
are positioned contiguously in the leftward and rightward direction to and coaxially
with each other, the cylindrical main body 71a of the connection pin 71 can move into
the second guide hole 58gh until it spans both of the first and second guide holes
57gh and 58gh.
[0136] When the first intake valve 61 (and the second intake valve 62) is in a closed state
and the first guide hole 57gh and the second guide hole 58gh are coaxial with and
contiguous in the leftward and rightward direction to each other, if no external force
is applied to the rod portion 71b of the connection pin 71, then the disconnection
piston 72 biased by the spring 73 urges the connection pin 71 leftwardly (rightwardly
in FIG. 10) as seen in FIG. 10. Consequently, the cylindrical main body 71a is fitted
fully in the first guide hole 57gh and the right end face of the cylindrical main
body 71a with which the disconnection piston 72 contacts is placed in flush with the
right opening end face of the first guide hole 57gh. Therefore, the first intake rocker
arm 57 and the second intake rocker arm 58 can rock independently of each other.
[0137] However, if external force is applied to the rod portion 71b of the connection pin
71 to push the connection pin 71 rightwardly (leftwardly in FIG. 11) as seen in FIG.
11, then the connection pin 71 pushes the disconnection piston 72 against the biasing
force of the spring 73. Consequently, the cylindrical main body 71a of the connection
pin 71 advances and fitted into the second guide hole 58gh. Therefore, the cylindrical
main body 71a of the connection pin 71 is positioned so as to span both of the first
guide hole 57gh and the second guide hole 58gh. As a result, the first intake rocker
arm 57 and the second intake rocker arm 58 are connected to each other by the connection
pin 71 and rock integrally with each other.
[0138] Then, if the external force to the connection pin 71 disappears, then the disconnection
piston 72 urges the connection pin 71 leftwardly by the biasing force of the spring
73 so that the connection pin 71 is placed into the first guide hole 57gh thereby
to cancel the connection.
[0139] In this manner, the first intake rocker arm 57 and the second intake rocker arm 58
are connected to each other by advancement (movement in the rightward direction) of
the connection pin 71 and rock integrally with each other. On the other hand, the
connection between the first intake rocker arm 57 and the second intake rocker arm
58 is canceled by retraction (movement in the leftward direction) of the connection
pin 71.
[0140] Referring to FIG. 6 (and FIG. 10), the axial line Cp of the connection pin 71 is
disposed between head side end portions 57tt and 58tt of the adjustment screws 57t
and 58t and the axial line Cr of the rocker arm shaft insertion holes 57h and 58h
in the cylinder axial line direction.
[0141] The cylinder head 33 tilted forward greatly includes a rectangular tubular outer
peripheral wall 100 configured from four wall portions including a left side wall
100L, a right side wall 100R, an upper wall 100U and a lower wall 100S. The rod portion
71b of the connection pin 71 projects leftwardly (in FIG. 10, rightwardly), and the
left side wall 100L of the outer peripheral wall 100 has a rod sliding hole 102 perforated
at a portion thereof to which the rod portion 71b is opposed in such a manner as to
extend leftwardly and rightwardly therethrough. A push rod 74 is inserted for sliding
movement in the rod sliding hole 102.
[0142] The push rod 74 has a disk portion 74a provided at a right end thereof and having
an increased diameter. The push rod 74 is fitted in the rod sliding hole 102 of the
left side wall 100L from the right side (in FIG. 10, the left side) while the disk
portion 74a at the right end thereof remains in the inside of the cylinder head 33.
The push rod 74 has a left end positioned in the inside of the rod sliding hole 102.
[0143] A right side face of the disk portion 74a at the right end of the push rod 74 is
opposed to the rod portion 71b projecting rightwardly of the connection pin 71 fitted
in the first guide hole 57gh of the first intake rocker arm 57.
[0144] While the connection pin 71 rocks together with the first intake rocker arm 57, the
disk portion 74a of the push rod 74 always has an area sufficient for the same to
always oppose to the rod portion 71b of the connection pin 71 which rocks within a
range within which the connection pin 71 can rock.
[0145] An electromagnetic solenoid 75 is attached from the outer side to the left side wall
100L of the cylinder head 33 and serves as a pressing force generation source for
driving the variable valve apparatus 70.
[0146] It is to be noted that the pressing force generation source can be configured applying
a hydraulic cylinder in addition to the electromagnetic solenoid 75.
[0147] As shown in FIGS. 10 and 11, an operating rod 76 projects rightwardly from the electromagnetic
solenoid 75 and is inserted from the left side into the rod sliding hole 102 in which
the push rod 74 is inserted from the right side. The left end of the push rod 74 and
the right end of the operating rod 76 are opposed to each other in the inside of the
rod sliding hole 102.
[0148] Referring to FIG. 6 (and FIG. 10), the axial line Cd of the pressing force transmission
members of the push rod 74 and the operating rod 76 inserted in the rod sliding hole
102 is always positioned on the crankcase 31 side and on the intake rocker arm shaft
55 side with respect to the axial line Cp of the connection pin 71 which is fitted
for rocking motion in the first guide hole 57gh of the first intake rocker arm 57.
[0149] FIG. 10 is a partial sectional view of the electromagnetic solenoid 75 in an inactive
state. In the disconnection state in which the connection pin 71 is urged leftwardly
through the disconnection piston 72 by the biasing force of the spring 73 to accommodate
the cylindrical main body 71a fully in the first guide hole 57gh, the push rod 74
assumes a leftwardly retracted position in which it contacts with the rod portion
71b of the connection pin 71. In the rod sliding hole 102, a sandwiched inner space
80 of a suitable width is formed in a sandwiched relationship between the push rod
74 and the operating rod 76 when the electromagnetic solenoid 75 is in an inactive
state.
[0150] FIG. 11 is a partial sectional view of the electromagnetic solenoid 75 in an active
state. By operation of the electromagnetic solenoid 75, the operating rod 76 projecting
rightwardly urges the connection pin 71 rightwardly (in FIG. 11, leftwardly) together
with the disconnection piston 72 against the biasing force of the spring 73. Consequently,
the cylindrical main body 71a of the connection pin 71 spans both of the first guide
hole 57gh and the second guide hole 58gh to place the first intake rocker arm 57 and
the second intake rocker arm 58 in a connection state.
[0151] The cylinder head 33 is a cast part configured from a nonmagnetic member made of
an aluminum alloy. The structure of the cylinder head 33 is described in detail with
reference to FIGS. 13 to 18.
[0152] An opening of the upstream side intake port 93 is formed on the upper wall 100U of
the cylinder head 33, and an opening end is formed on the lower wall 100S such that
it projects a little to the outside of the downstream side exhaust port 97.
[0153] Further, the ignition plug 49 is mounted on the left side wall 100L of the cylinder
head 33, and the electromagnetic solenoid 75 is attached to the left side wall 100L
as described hereinabove (refer to FIGS. 3 and 8).
[0154] Therefore, an ignition plug mounting hole 101 is formed at a central recessed portion
of the left side wall 100L of the cylinder head 33 such that the ignition plug 49
is mounted obliquely as shown in FIG. 14. Further, the rod sliding hole 102 in which
the operating rod 76 of the electromagnetic solenoid 75 and the push rod 74 are inserted
is perforated at a position of the cylinder head 33 displaced a little to the upper
wall 100U side from the center in the proximity of the mating face 100t of the cylinder
head 33 with the head cover 34.
[0155] A rod boss portion 102b is formed at an outer side opening portion of the rod sliding
hole 102 and has an increased inner diameter portion 102a formed thereon such that
the inner diameter of the rod sliding hole 102 increases over two stages (refer to
FIG. 17).
[0156] Referring to FIG. 14, an attachment boss portion 103p is formed on the left side
wall 100L of the cylinder head 33 and has an attachment hole at a position thereof
displaced to the lower wall 100S side from the center in the proximity of the mating
face 100t. Further, a rib portion 103pr is formed so as to extend along the mating
face 100t from the rod boss portion 102b toward the attachment boss portion 103p.
[0157] The rod boss portion 102b is located on the upper wall 100U side with respect to
the ignition plug mounting hole 101, and the attachment boss portion 103p is located
on the lower wall 100S side with respect to the ignition plug mounting hole 101. The
rib portion 103pr which connects the rod boss portion 102b and the attachment boss
portion 103p to each other is formed across the central ignition plug mounting hole
101 on the mating face 100t side.
[0158] An attachment boss portion 103q and a rib portion 103qr are formed on the opposite
side to the attachment boss portion 103p with respect to the rod boss portion 102b.
An attachment boss portion 103r is formed at a rather spaced position from the rod
boss portion 102b on the opposite side to the mating face 100t. A rib portion 103rr
is formed so as to extend from the rod boss portion 102b toward the attachment boss
portion 103r.
[0159] In particular, two rib portions 103pr and 103qr extend from the rod boss portion
102b to the opposite sides to each other along the mating face 100t, and one rib portion
103rr extends in a direction perpendicular to the rib portions 103pr and 103qr. The
attachment boss portions 103p, 103q and 103r are formed at end portions of the rib
portions 103pr and 103qr and the rib portion 103rr, respectively.
[0160] The three attachment boss portions 103p, 103q and 103r and the three rib portions
103pr, 103qr and 103rr described above are swollen from an outer wall face of the
left side wall 100L such that end faces thereof form an attachment face (portion indicated
by lattice hatching lines in FIG. 14) of a continuous same plane.
[0161] Meanwhile, as shown in FIG. 10, the electromagnetic solenoid 75 includes a fixed
core 75s and a movable core 75d fixedly secured integrally to an end portion of the
operating rod 76 which extends through the fixed core 75s. The electromagnetic solenoid
75 includes a solenoid main body which includes the movable core 75d around which
a coil 75c is provided circumferentially. The solenoid main body is accommodated in
accommodation cases 77 and 78 formed as two divisional members.
[0162] A spring 79 is interposed between the fixed core 75s and the movable core 75d.
[0163] The accommodation cases 77 and 78 are made of a metal having a high thermal conductivity.
[0164] The accommodation case 77 is configured from a cylindrical portion 77a which covers
the periphery of the coil 75c, a bottom wall portion 77b for the cylindrical portion
77a, and three attachment arm portions 77pr, 77qr and 77rr extending radially from
the bottom wall portion 77b. Attachment boss portions 77p, 77q and 77r having attachment
holes are formed at end portions of the attachment arm portions 77pr, 77qr and 77rr,
respectively (refer to FIGS. 3 and 14).
[0165] A rod boss portion 77bb is provided at the center of the bottom wall portion 77b
and projects inwardly and outwardly. The rod boss portion 77bb supports the operating
rod 76 for pivotal motion and for sliding movement. The portion of the rod boss portion
77bb which projects to the inner side configures the fixed core 75s.
[0166] The accommodation case 78 has a bottomed cylindrical shape and is fitted on the opening
end of the cylindrical portion 77a of the accommodation case 77 such that it covers
the movable core 75d.
[0167] It is to be noted that an elastic member 78r is pasted to the bottom face of the
accommodation case 78 of the bottomed cylindrical shape in an opposing relationship
to the movable core 75d.
[0168] The three attachment arm portions 77pr, 77qr and 77rr and the three attachment boss
portions 77p, 77q and 77r extending radially from the bottom wall portion 77b of the
accommodation case 77 correspond to the three rib portions 103pr, 103qr and 103rr
and the three attachment boss portions 103p, 103q and 103r of the left side wall 100L
of the cylinder head 33, respectively, and are opposed to each other. Thus, the attachment
boss portions 77p, 77q and 77r and the attachment arm portions 77pr, 77qr and 77rr
are abutted with the attachment face which is the same continuous face formed by the
attachment boss portions 103p, 103q and 103r and the rib portions 103pr, 103qr and
103rr. Then, the attachment boss portions of them are fastened to each other by bolts
104p, 104q and 104r to attach the electromagnetic solenoid 75 to the left side wall
100L of the cylinder head 33 (refer to FIGS. 3 and 14).
[0169] Thereupon, the rod boss portion 77bb formed in a projecting manner at the center
of the bottom wall portion 77b of the accommodation case 77 is inserted into the increased
inner diameter portion 102a of the rod sliding hole 102 of the cylinder head 33 with
a seal member 83 and an O-snap ring 84 interposed therebetween (refer to FIG. 10).
[0170] The bottom wall portion 77b and the attachment arm portions 77pr and 77qr of the
accommodation case 77 of the electromagnetic solenoid 75 protrude to the head cover
34 side from a mating face 104h of the cylinder head 33 with the head cover 34 as
indicated by an alternate long and two short dashes line in FIG. 14(refer to FIGS.
8 and 14).
[0171] However, the electromagnetic solenoid 75 is attached only to the cylinder head 33.
[0172] Referring to FIG. 14, the electromagnetic solenoid 75 attached to the cylinder head
33 in this manner is provided at a position which is on the head cover 34 side with
respect to the ignition plug 49 and does not overlap with the ignition plug center
axial line Cs directed by the ignition plug 49 as viewed in the cylinder axial line
direction shown in FIG. 7.
[0173] The accommodation case 77 has an attachment arm portion 77qr which is abutted with
the rib portion 103pr formed across the ignition plug mounting hole 101 at the center
of the cylinder head 33 on the mating face 100t. The attachment arm portion 77qr has
a recessed portion 77d formed thereon and open toward the ignition plug 49 side such
that it extends across and keeps away from the ignition plug center axial line Cs
directed by the ignition plug 49 mounted in the ignition plug mounting hole 101 between
the attachment boss portion 103p and the attachment arm portion 77rr (refer to FIGS.
3, 8 and 14).
[0174] When the power unit 20 is incorporated in the scooter type motorcycle 1, the electromagnetic
solenoid 75 attached to the left side wall 100L of the cylinder head 33 of the internal
combustion engine 30 is covered, on the outer side (left side) in the vehicle widthwise
direction and the front side thereof, in a surrounding manner with the connection
pipe 6 of the vehicle body frame.
[0175] The present OHC type internal combustion engine 30 is a water-cooled internal combustion
engine, and a water pump 150 is attached to the right side wall 100R of the cylinder
head 33 on the opposite side to the left side wall 100L to which the electromagnetic
solenoid 75 is attached.
[0176] A circular hole 105 of a large diameter is formed in the right side wall 100R of
the cylinder head 33 (refer to FIG. 15). A water pump body 151 of a cylindrical shape
of the water pump 150 is fitted watertight in and supported by the circular hole 105
(refer to FIG. 8).
[0177] Referring to FIG. 8, the water pump body 151 of the water pump 150 is configured
from a long cylindrical portion 151a and a short cylindrical portion 151b. The long
cylindrical portion 151a is elongated in an axial direction of a pump driving shaft
153 and supports the pump driving shaft 153 for rotation through a bearing 155. The
short cylindrical portion 151b is expanded in a diametrical direction and short in
the axial direction. The short cylindrical portion 151b is extended in a diametrical
direction at one opening end thereof so that it accommodates part of the impeller
154 fitted on the pump driving shaft 153. The long cylindrical portion 151a is fitted
in and secured to the circular hole 105 of the right side wall 100R of the cylinder
head 33 with an O-snap ring 156 interposed therebetween such that the pump driving
shaft 153 is disposed coaxially with the camshaft 54. The pump driving shaft 153 is
fitted and directly coupled, at a left end thereof, in and to a fitting hole perforated
on a right end face of the camshaft 54.
[0178] A water pump cover 152 covers a right opening of the short cylindrical portion 151b
of the water pump body 151 and cooperates with the short cylindrical portion 151b
to accommodate the impeller 154 therebetween. The water pump cover 152 is superposed
on the opening end face of the short cylindrical portion 151b.
[0179] Four bolt holes are formed on an outer circumference of the short cylindrical portion
151b of the water pump body 151. Also on the water pump cover 152, four bolt holes
are formed corresponding to the bolt holes of the water pump body 151 (refer to FIGS.
4 and 15).
[0180] Three attachment boss portions 106 having a female threaded hole are formed on the
right side wall 100R of the cylinder head 33 and around the circular hole 105. Bolt
holes at the three corresponding locations of the water pump body 151 and the water
pump cover 152 are abutted with the three attachment boss portions 106 of the cylinder
head 33 and fastened together individually by the bolts 157a to attach the water pump
150 to the right side wall 100R of the cylinder head 33.
[0181] It is to be noted that the bolt holes at the remaining one location of the water
pump body 151 and the water pump cover 152 project to the head cover 34 side from
the mating face 100t of the cylinder head 33 with the head cover 34. The cylinder
head 33 and the head cover 34 are fastened together by bolts 157b (refer to FIG. 8).
[0182] Referring to FIG. 4, to the water pump cover 152, a water suction tube portion 152a
extends from the intake port swollen on the right side of the pump driving shaft 153
along the right side face of the cylinder head 33 toward the cylinder block 32 side.
Further, the discharge port directed in a tangential direction from the outer periphery
of the impeller 154 is extended such that a water discharge tube portion 152b extends
to the water pump cover 152. Furthermore, an air vent tube portion 152c is provided
in an upwardly projecting manner at an upper portion of the outer periphery of the
impeller 154.
[0183] A water outlet opening 107 of a water jacket 33w in the cylinder head 33 is formed
in the right side wall 100R of the cylinder head 33. Further, two working holes 108
and 109 are perforated in the right side wall 100R along the mating face 100t with
the head cover 34 around the circular hole 105.
[0184] The working holes 108 and 109 are located coaxially with the intake rocker arm shaft
55 and the exhaust rocker arm shaft 56.
[0185] Referring to FIG. 4, the water suction tube portion 152a of the water pump 150 extending
to the cylinder block 32 side is connected to a thermostat 160.
[0186] A branch connection pipe 161 is provided in a projecting manner at the water outlet
opening 107 of the cylinder head 33. The main pipe of the branch connection pipe 161
is connected to an upstream side radiator tank 47a of the radiator 47 through a radiator
inlet hose 162 while the branch pipe of the branch connection pipe 161 is connected
to the thermostat 160 through a bypass hose 164.
[0187] A downstream side radiator tank 47b of the radiator 47 and the thermostat 160 are
connected to each other by a radiator outlet hose 163.
[0188] A water discharge hose 165 connects a water inlet opening of the water jacket in
the cylinder block 32 and the water discharge tube portion 152b of the water pump
150 to each other.
[0189] It is to be noted that the air vent tube portion 152c provided in an upwardly projecting
manner on the water pump 150 is connected to the upper branch connection pipe 161
through an air vent pipe 166.
[0190] Upon warming up while the internal combustion engine 30 does not yet heat up, the
thermostat 160 closes up the path of water flowing in from the radiator 47 but opens
the water path bypassing from the cylinder head 33 so that warming up is accelerated
through the path of water which does not pass the radiator 47. Then, when the warming
up comes to an end and normal operation is entered, the thermostat 160 closes up the
water path for bypassing from the cylinder head 33 but opens the water path flowing
in from the radiator 47. Consequently, cooling water cooled by the radiator 47 is
circulated from the cylinder block 32 in the cylinder head 33 to cool the cylinder
block 32 and the cylinder head 33.
[0191] The cylinder head 33 has an inner wall 110 formed in parallel to the right side wall
100R on the inner side of the outer peripheral wall 100 (refer to FIGS. 9 and 13).
The inner wall 110 cooperates with the right side wall 100R to configure the cam chain
chamber 52 therebetween.
[0192] A bearing circular hole 111 is formed coaxially with the circular hole 105 in the
inner wall 110 and has a diameter substantially equal to that of the circular hole
105 formed in the right side wall 100R. Also an intake rocker arm shaft supporting
portion 112 and an exhaust rocker arm shaft supporting portion 113 are formed on the
inner wall 110. The intake rocker arm shaft supporting portion 112 and the exhaust
rocker arm shaft supporting portion 113 have an intake rocker arm shaft supporting
hole 112h and an exhaust rocker arm shaft supporting hole 113h having an equal diameter
to that of and disposed coaxially with the working holes 108 and 109 formed in the
right side wall 100R, respectively.
[0193] The working holes 108 and 109 for perforating the rocker arm shaft supporting holes
112h and 113h are closed up from the outside with plug members 65 and 66, respectively
(refer to FIGS. 7 and 9).
[0194] When the water pump 150 is attached to the right side wall 100R of the cylinder head
33, the short cylindrical portion 151b of the water pump body 151 is positioned closely
to and covers the plug members 65 and 66 from the outside (refer to FIGS. 4 and 7).
[0195] Accordingly, coming off of the plug members 65 and 66 is prevented by the water pump
150 attached to the cylinder head 33.
[0196] Stud bolt fastening holes 115 and 116 are perforated on the opposite outer sides
of the intake rocker arm shaft supporting portion 112 and the exhaust rocker arm shaft
supporting portion 113 of the inner wall 110, respectively, such that they extend
through the inner wall 110 in the cylinder axial line direction (refer to FIGS. 13
and 16).
[0197] The stud bolts 180 are fitted in the stud bolt fastening holes 115 and 116.
[0198] The left side wall 100L is recessed to the inner side from the mating face 100t with
the head cover 34 and is opposed to the inner wall 110. A bearing circular hole 121
of a diameter smaller than that of the bearing circular hole 111 of the inner wall
110 is formed coaxially with the bearing circular hole 111. An intake rocker arm shaft
supporting portion 122 and an exhaust rocker arm shaft supporting portion 123 are
formed in the left side wall 100L. The intake rocker arm shaft supporting portion
122 and the exhaust rocker arm shaft supporting portion 123 have an intake rocker
arm shaft supporting hole 122h and an exhaust rocker arm shaft supporting hole 123h,
respectively. The intake rocker arm shaft supporting hole 122h and the exhaust rocker
arm shaft supporting hole 123h have a diameter equal to and are disposed coaxially
in an opposing relationship to the intake rocker arm shaft supporting hole 112h and
the exhaust rocker arm shaft supporting hole 113h of the inner wall 110, respectively.
[0199] The intake rocker arm shaft supporting portion 122 and the exhaust rocker arm shaft
supporting portion 123 have stud bolt fastening holes 125 and 126 perforated therein
at a position rather offset leftwardly on the outer sides thereof and extending in
the cylinder axial direction through them (refer to FIGS. 13 and 14).
[0200] The stud bolts 180 are inserted in the stud bolt fastening holes 125 and 126.
[0201] The rod sliding hole 102 is formed between the intake rocker arm shaft supporting
hole 122h of the left side wall 100L and the stud bolt fastening hole 125 in the proximity
of the intake rocker arm shaft supporting hole 122h. Particularly, the rod sliding
hole 102 is formed at a position overlapping with the intake rocker arm shaft supporting
hole 122h in the cylinder axial line direction (refer to FIGS. 13, 17 and 18).
[0202] The rod sliding hole 102 overlaps with a nut 181 as viewed in the cylinder axial
line direction and is provided in the proximity of the stud bolt fastening hole 125.
[0203] Further, an oil supply hole 130 is perforated in the cylinder axial line direction
toward the rod sliding hole 102 in the proximity of the stud bolt fastening hole 125
and is open to the end face of the left side wall 100L on the head cover 34 side.
[0204] The oil supply hole 130 and the rod sliding hole 102 have such a positional relationship
that the center axial lines thereof are spaced away from each other and cross perpendicularly
with each other.
[0205] Accordingly, the oil supply hole 130 communicates the inner side space of the cylinder
head 33 and the rod sliding hole 102 with each other.
[0206] The camshaft 54 is supported for rotation in the bearing circular hole 111 and the
bearing circular hole 121 provided coaxially with each other in the inner wall 110
and the left side wall 100L which are opposed to each other.
[0207] Referring to FIG. 8, the camshaft 54 is fitted at a left end thereof for rotation
in the bearing circular hole 121 and at a right side portion thereof for rotation
in the bearing circular hole 111 through a bearing 82.
[0208] It is to be noted that the camshaft 54 projects into the cam chain chamber 52 on
the right side with respect to the bearing 82 and has the driven cam chain sprocket
wheel 53 fitted at a right end thereof.
[0209] Further, a decompression mechanism 85 is incorporated between the bearing 82 and
the exhaust cam lobe 54e of the camshaft 54 on the left side of the bearing 82 utilizing
the exhaust cam lobe 54e.
[0210] The intake rocker arm shaft 55 is fitted at the opposite ends thereof in the intake
rocker arm shaft supporting hole 112h and the intake rocker arm shaft supporting hole
122h, which are coaxial with each other, of the inner wall 110 and the left side wall
100L which are opposed to each other such that the intake rocker arm shaft 55 is supported
in the supporting holes 112h and 122h, respectively (refer to FIGS. 7 and 9). Further,
the exhaust rocker arm shaft 56 is fitted at the opposite ends thereof in the exhaust
rocker arm shaft supporting hole 113h and the exhaust rocker arm shaft supporting
hole 123h, which are coaxial with each other, of the inner wall 110 and the left side
wall 100L such that the exhaust rocker arm shaft 56 is supported in the holes 113h
and 123h, respectively (refer to FIGS. 7 and 8).
[0211] All of the intake rocker arm shaft supporting portion 112, exhaust rocker arm shaft
supporting portion 113 and opening end portions of the stud bolt fastening holes 115
and 116 of the inner wall 110 and the intake rocker arm shaft supporting portion 122,
exhaust rocker arm shaft supporting portion 123 and opening end portions of the stud
bolt fastening holes 125 and 126 of the left side wall 100L have an end face (portions
indicated by lattice hatching lines in FIG. 13) lying on the same plane with a mating
face 104t of the cylinder head 33 with the head cover 34.
[0212] Referring to FIG. 13, a pin insertion hole 112p of a small diameter is formed so
as to extend in the cylinder axial line direction through a portion of the intake
rocker arm shaft supporting portion 112 of the inner wall 110 from an end face thereof
to the intake rocker arm shaft supporting hole 112h.
[0213] In the intake rocker arm shaft 55 fitted in the intake rocker arm shaft supporting
hole 112h, a pin insertion hole 55p is perforated such that it extends through the
intake rocker arm shaft 55 along the axial center in a diametrical direction in a
corresponding relationship to the pin insertion hole 112p. The pin insertion holes
112p and 55p are formed coaxially in the intake rocker arm shaft supporting portion
112 and the intake rocker arm shaft 55, respectively. A pin member 142 is inserted
in the pin insertion holes 112p and 55p from the head cover 34 side to secure the
intake rocker arm shaft 55 to the intake rocker arm shaft supporting portion 112 (refer
to FIG. 9).
[0214] A pin insertion hole 123p of a small diameter is formed so as to extend in the cylinder
axial direction through a portion of the exhaust rocker arm shaft supporting portion
123 of the left side wall 100L from an end face thereof to the exhaust rocker arm
shaft supporting hole 123h.
[0215] A pin insertion hole 56p is perforated so as to extend through the exhaust rocker
arm shaft 56, which is inserted in the exhaust rocker arm shaft supporting hole 123h,
along the axial center in a diametrical direction in a corresponding relationship
to the pin insertion hole 123p. A pin member 143 is inserted from the head cover 34
side into the pin insertion holes 123p and 56p formed coaxially in both of the exhaust
rocker arm shaft supporting portion 123 and the exhaust rocker arm shaft 56 to secure
the exhaust rocker arm shaft 56 to the exhaust rocker arm shaft supporting portion
123 (refer to FIG. 8).
[0216] It is to be noted that a working hole 127 is formed so as to extend in the cylinder
axial line direction through a portion of the intake rocker arm shaft supporting portion
122 of the left side wall 100L from an end face thereof to the intake rocker arm shaft
supporting hole 122h.
[0217] A reinforcement plate 140 bridges the opening end portions of the stud bolt fastening
holes 115 and 116 of the inner wall 110 (refer to FIG. 7).
[0218] The reinforcement plate 140 abuts with end faces of the opening end portions of the
stud bolt fastening holes 115 and 116 and end faces of the intake rocker arm shaft
supporting portion 112 and the exhaust rocker arm shaft supporting portion 113. The
opposite end portions of the reinforcement plate 140 are fastened together with the
cylinder head 33 by the stud bolts 180.
[0219] The reinforcement plate 140 is bent and extends, at a central portion of a side edge
between the opposite end portions thereof on the cam chain chamber 52 side (left side),
to the bearing circular hole 111 side to form a bent plate portion 140b (refer to
FIGS. 8 and 9).
[0220] As shown in FIG. 6, the bent plate portion 140b has a width substantially equal to
the distance between the center axes of the intake rocker arm shaft supporting hole
112h and the exhaust rocker arm shaft supporting hole 113h. The bent plate portion
140b partially blocks the openings of the intake rocker arm shaft supporting hole
112h and the exhaust rocker arm shaft supporting hole 113h. Meanwhile, an end portion
of the bent plate portion 140b which is recessed arcuately partially blocks the opening
of the bearing circular hole 111.
[0221] Accordingly, as shown in FIGS. 6 and 8, the reinforcement plate 140 prevents, by
the bent plate portion 140b thereof, the outer race of the bearing 82, which supports
the camshaft 54 for rotation, from coming off from the bearing circular hole 111 thereby
to restrict the camshaft 54 from moving in the axial direction.
[0222] Simultaneously, as shown in FIGS. 6 and 9, the bent plate portion 140b of the reinforcement
plate 140 prevents the intake rocker arm shaft 55 and the exhaust rocker arm shaft
56 from coming off from the intake rocker arm shaft supporting hole 112h and the exhaust
rocker arm shaft supporting hole 113h, respectively. Consequently, the intake rocker
arm shaft 55 and the exhaust rocker arm shaft 56 are restricted from moving in the
axial direction.
[0223] Further, the reinforcement plate 140 has a pin insertion hole 140p perforated at
a position of the cylinder head 33 corresponding to the pin insertion hole 112p formed
in the intake rocker arm shaft supporting portion 112. The pin insertion hole 140p
is perforated coaxially with the pin insertion hole 112p.
[0224] On the other hand, a reinforcement plate 141 bridges the opening end portions of
the stud bolt fastening holes 125 and 126 of the left side wall 100L.
[0225] The reinforcement plate 141 is abutted with end faces of the opening end portions
of the stud bolt fastening holes 125 and 126 and end faces of the intake rocker arm
shaft supporting portion 122 and the exhaust rocker arm shaft supporting portion 123.
The opposite end portions of the reinforcement plate 141 are fastened together with
the cylinder head 33 by the stud bolts 180.
[0226] The reinforcement plate 141 has a recessed portion 141P formed so as to keep away
from the pin insertion hole 123p of the exhaust rocker arm shaft supporting portion
123 (refer to FIG. 7).
[0227] Further, the reinforcement plate 141 closes up the working hole 127 of the intake
rocker arm shaft supporting portion 122 and partly covers the opening of the oil supply
hole 130 as shown in FIG. 7.
[0228] The reinforcement plate 140 which bridges the opening end portions of the stud bolt
fastening holes 115 and 116 of the inner wall 110 is fastened at the opposite ends
thereof together with the cylinder head 33 by the stud bolts 180 and bridges the opening
end portions of the stud bolt fastening holes 125 and 126 of the left side wall 100L.
However, since the reinforcement plate 140 is fastened at the opposite ends thereof
together with the cylinder head 33 by the stud bolts 180, the cylinder head 33 can
be maintained in a high rigidity state.
[0229] It is to be noted that the pin member 142 fitted in the pin insertion holes 112p
and 55p of both of the intake rocker arm shaft supporting portion 112 and the intake
rocker arm shaft 55 extends through the pin insertion hole 140p of the reinforcement
plate 140 such that end portions thereof are projected (refer to FIG. 9).
[0230] Further, the pin member 143 fitted in the pin insertion holes 123p and 56p of both
of the exhaust rocker arm shaft supporting portion 123 and the exhaust rocker arm
shaft 56 extends through the recessed portion 141p of the reinforcement plate 141
such that end portions thereof are projected (refer to FIG. 9).
[0231] The head cover 34 is swollen by a great amount at a central portion thereof to form
a swollen portion 34a and has an internal space formed so as to be recessed to the
inner side from the swollen portion 34a. The internal space of the head cover 34 is
partitioned by a breather plate 145 attached to the head cover 34 from the inner side
to form a breather chamber 34b.
[0232] The breather plate 145 is provided so as to extend in parallel to the mating face
100t of the cylinder head 33 on the head cover 34 side with a predetermined distance
left therebetween.
[0233] As shown in FIG. 9, end portions of the pin members 142 and 143 extending through
and projecting from the reinforcement plates 140 and 141 are positioned closely to
the breather plate 145 with a small gap left therebetween.
[0234] Accordingly, the amount of movement of the pin members 142 and 143 fitted in the
pin insertion holes 112p and 123p of the intake rocker arm shaft supporting portion
112 and the exhaust rocker arm shaft supporting portion 123 is restricted by the breather
plate 145 attached to the head cover 34. Consequently, the pin members 142 and 143
are prevented from coming off from the pin insertion holes 112p and 123p, respectively.
[0235] Referring to FIG. 2 which shows a view of the power unit 20 incorporated in the vehicle
as viewed in front elevation, an exit portion 34c of the breather chamber 34b of the
head cover 34 is formed at an upper portion of the swollen portion 34a such that the
opening thereof is directed to the right side (water pump 150 side). A breather hose
146 is connected at an end portion thereof to the exit portion 34c, extends toward
the water pump 150 side and is curved so as to be directed rearwardly. Further, the
breather hose 146 is connected to the clean side of the air cleaner 27.
[0236] Accordingly, the breather hose 146 does not interfere with the electromagnetic solenoid
75 attached to the left side wall 100L of the cylinder head 33.
[0237] Now, a lubricating system in the cylinder head 33 and the valve mechanism 50 is described.
[0238] The stud bolt fastening hole 115 of the cylinder head 33 is utilized as a path of
oil supplied from the cylinder block 32 side. Referring to FIGS. 7 and 13, an oil
passage 131 is formed from an intermediate portion of the stud bolt fastening hole
115 toward the upper wall 100U. The oil passage 131 is bent at an end portion thereof
and communicated with an oil passage 132 which extends toward the left side wall 100L
in the upper wall 100U. The oil passage 132 is bent at an end portion thereof and
is communicated with an oil passage 133 which extends toward the bearing circular
hole 121 in the left side wall 100L.
[0239] In the cylinder head 33 tilted forward to a position near to a horizontal position,
the oil passage 132 perforated horizontally in the upper wall 100U is positioned at
an uppermost location. Injection holes 132a and 132b are formed in a branching manner
at two locations of the oil passage 132 above and corresponding to the first intake
rocker arm 57 and the second intake rocker arm 58, respectively (refer to FIGS. 6
and 13).
[0240] Oil injected from the injection holes 132a and 132b is dispersed to end portions
of the valve side arm portions 57v and 58v and the adjustment screws 57t and 58t of
the first intake rocker arm 57 and the second intake rocker arm 58, respectively (refer
to FIGS. 6 and 10).
[0241] The oil passage 133 in the left side wall 100L is perforated in the proximity of
the electromagnetic solenoid 75 attached to the left side wall 100L and extends through
the stud bolt fastening hole 125. Further, the oil passage 133 passes in a crossing
relationship with the intake rocker arm shaft supporting hole 122h with a distance
left therebetween. The oil passage 133 is communicated at an end portion thereof with
an oil inlet passage 134 which is formed so as to extend leftwardly of the bearing
circular hole 121 shown in FIG. 8 (refer to FIGS. 13 and 14).
[0242] It is to be noted that the stud bolt fastening hole 125 is structured such that it
is closed at the top and the bottom thereof.
[0243] An oil branch passage 133a connects the oil passage 133 and the intake rocker arm
shaft supporting hole 122h which crosses with the oil passage 133 to each other (refer
to FIGS. 9 and 18).
[0244] Referring to FIG. 8, the camshaft 54 has a shaft hole 54a which is open at a left
end thereof which faces the oil inlet passage 134 and has extraction oil passages
54b, 54c and 54d perforated therein in a diametrical direction from the shaft hole
54a.
[0245] Accordingly, oil introduced into the shaft hole 54a of the camshaft 54 from the oil
passage 133 through the oil inlet passage 134 rubricates the bearing portions by communicating
extraction oil passage 54b on the left side with the bearing circular hole 121 of
the left side wall 100L. Meanwhile, the extraction oil passage 54c at the center is
open to an outer peripheral face of the second intake cam lobe 54ii so that the oil
lubricates the slidably contacting portion of the second intake cam lobe 54ii with
the slipper 58s of the second intake rocker arm 58. Further, the extraction oil passage
54d on the right side is open toward the decompression mechanism 85 so that the oil
lubricates the decompression mechanism 85.
[0246] Referring to FIG. 9, the intake rocker arm shaft 55 fitted in and supported by the
intake rocker arm shaft supporting hole 122h has a shaft hole 55a open at a left end
thereof. An introduction oil passage 55b is formed at a portion of the intake rocker
arm shaft 55 on the left side of the shaft hole 55a such that it extends through the
shaft hole 55a coaxially with the oil branch passage 133a. Oil diverted from the oil
passage 133 to the oil branch passage 133a is introduced into the shaft hole 55a from
the introduction oil passage 55b of the intake rocker arm shaft 55. Further, an extraction
oil passage 55c is formed in the intake rocker arm shaft 55 in the proximity of the
right end of the shaft hole 55a from the shaft hole 55a toward the second guide hole
58gh of the second intake rocker arm 58 (refer to FIG. 10).
[0247] Referring to FIG. 10, an introduction oil passage 58d is formed in the second intake
rocker arm 58 such that it communicates the extraction oil passage 55c and the right
end side of the second guide hole 58gh with each other.
[0248] An adjustment oil passage 58e is formed in the valve side arm portion 58v of the
second intake rocker arm 58 such that it extends upwardly outwardly from the right
end side of the second guide hole 58gh.
[0249] Accordingly, oil introduced into the second guide hole 58gh from the shaft hole 55a
of the second intake rocker arm 58 through the extraction oil passage 55c and the
introduction oil passage 58d lubricates the disconnection piston 72 for sliding movement.
Then, the oil is discharged from the adjustment oil passage 58e upon sliding movement
of the disconnection piston 72 and then adjusted.
[0250] It is to be noted that the valve side arm portion 57v of the first intake rocker
arm 57 has an introduction oil passage 57d perforated therein so as to extend upwardly
outwardly from the first guide hole 57gh. The valve side arm portion 57v further has
an oil passage 57e perforated on the opposite side to and coaxially with the introduction
oil passage 57d.
[0251] Oil dispersed to an upper end portion of the valve side arm portion 57v of the first
intake rocker arm 57 flows along the surface of the valve side arm portion 57v into
the introduction oil passage 57d and lubricates the disconnection piston 72 for sliding
movement. Further, the first intake rocker arm 57 is lubricated for rocking motion
by the oil passing through the oil passage 57e.
[0252] The oil supply hole 130 communicates the rod sliding hole 102 in which the operating
rod 76 of the electromagnetic solenoid 75 and the push rod 74 of the variable valve
apparatus 70 are inserted and the inner side space of the cylinder head 33 with each
other. The oil supply hole 130 is positioned below an outer periphery of an annular
opening end face 125t of the stud bolt fastening hole 125 as viewed in the cylinder
axial line direction shown in FIG. 13 of the cylinder head 33 which is tilted forward
to a posture close to the horizontal posture. An oil guide groove 135 is formed between
the mating face 100t of the cylinder head 33, which is formed on the left side along
the outer periphery of the opening end face 125t, and the opening end face 125t.
[0253] The oil guide groove 135 introduces oil injected from the oil passage 132 in the
upper wall 100U of the cylinder head 33 through the injection hole 132a and so forth
and sticking to the wall face of the cylinder head 33 on the upper wall 100U side
into the oil supply hole 130.
[0254] A rib 136 is provided which extends leftwardly horizontally from a position at which
it contacts with a lower edge of the oil supply hole 130 below the oil guide groove
135 to the mating face 100t. Also oil staying above the rib 136 is admitted into the
oil supply hole 130.
[0255] Further, as shown in FIG. 7, the stud bolts 180 extend through the stud bolt fastening
holes 125 and fasten the reinforcement plate 141 together with the cylinder head 33,
and the hexagonal nuts 181 are screwed with the stud bolts 180. The hexagonal nuts
181 are fastened such that one angular portion thereof is specifically directed downwardly
in comparison with the other angular portions. Consequently, oil sticking to the hexagonal
nuts 181 is guided by the downwardly directed angular portions and flows downwardly
along the surface of the reinforcement plate 141 from the angular portions and then
flows round to a side edge of the reinforcement plate 141. Therefore, the oil is easily
admitted into the oil supply hole 130.
[0256] In the present variable valve apparatus 70, when the electromagnetic solenoid 75
is in an inactive state (state in which the first and second intake rocker arms 57
and 58 are not connected to each other by the connection pin 71 and can rock independently
of each other), the sandwiched inner space 80 defined by and between the operating
rod 76 and the push rod 74 in the rod sliding hole 102 is positioned as illustrated
in FIG. 10. In this position of the sandwiched inner space 80, the oil supply hole
130 for supplying oil into the sandwiched inner space 80 is offset to the push rod
74 side (right side) such that a left end portion of the push rod 74 faces the oil
supply hole 130 while the operating rod 76 is positioned so as not to face the oil
supply hole 130. Consequently, the sandwiched inner space 80 has such a positional
relationship that part thereof communicates with the oil supply hole 130.
[0257] The oil supply hole 130 has such a positional relationship that it is directed in
the cylinder axial line direction and has a center axial line spaced away from and
crossing perpendicularly with that of the rod sliding hole 102. The area of the communication
port on the boundary between the oil supply hole 130 and the rod sliding hole 102
is small in comparison with that where the center axial lines of them cross perpendicularly
with each other. In addition, when the electromagnetic solenoid 75 is in an inactive
state, the oil supply hole 130 is offset to the push rod 74 side with respect to the
sandwiched inner space 80. Consequently, the communication port on the boundary between
the oil supply hole 130 and the rod sliding hole 102 is partly closed by the push
rod 74. Therefore, the sandwiched inner space 80 assumes a state close to that of
a closed space.
[0258] In FIG. 10, oil supplied from the oil supply hole 130 to the sandwiched inner space
80 when the electromagnetic solenoid 75 is in an inactive state is indicated by scattered
points.
[0259] As seen in FIG. 10, the sandwiched inner space 80 is communicated only partly with
the oil supply hole 130 but is in a state close to a state of a closed space.
[0260] Further, as shown in FIG. 7, the reinforcement plate 141 which bridges the opening
end portions of the stud bolt fastening holes 125 and 126 of the left side wall 100L
of the cylinder head 33 covers approximately one half of the opening of the oil supply
hole 130 as viewed in the cylinder axial line direction. Therefore, flowing out of
oil in the sandwiched inner space 80 from the oil supply hole 130 is inhibited.
[0261] In this manner, when the electromagnetic solenoid 75 is in an inactive state, the
sandwiched inner space 80 filled with oil supplied from the oil supply hole 130 is
in a state close to that of a closed space, and oil is inhibited from flowing out
from the oil supply hole 130. Therefore, at an initial stage when the electromagnetic
solenoid 75 is operated to project the operating rod 76, flowing out of oil in the
sandwiched inner space 80 from the oil supply hole 130 is inhibited. Consequently,
the damper function of the operating rod 76 as an oil damper which pushes the push
rod 74 through the oil in the sandwiched inner space 80 can be raised, and an impact
or vibration by collision can be damped.
[0262] As the operating rod 76 moves rightwardly by operation of the electromagnetic solenoid
75, also the push rod 74 moves rightwardly through the oil in the sandwiched inner
space 80.
[0263] Since also the sandwiched inner space 80 moves rightwardly together with the movement
of the push rod 74, the offset amount of the oil supply hole 130 offset rightwardly
with respect to the sandwiched inner space 80 decreases. Consequently, while the oil
in the sandwiched inner space 80 gradually flows out from the oil supply hole 130,
the sandwiched inner space 80 becomes smaller and the operating rod 76 approaches
the push rod 74 until it is finally abutted with the push rod 74.
[0264] Accordingly, since the operating rod 76 is abutted with the push rod 74 in such a
manner as to catch up the push rod 74 in a state in which the push rod 74 is moving
rightwardly, the impact upon abutment can be suppressed very low.
[0265] An operation state of the electromagnetic solenoid 75 when the operating rod 76 ends
the rightward movement is illustrated in FIG. 11.
[0266] The push rod 74 and the connection pin 71 move rightwardly together with the operating
rod 76 and the connection pin 71 connects the first and second intake rocker arms
57 and 58 to each other so that they rock integrally with each other. The right end
of the operating rod 76 abuts with the left end of the push rod 74 to eliminate the
sandwiched inner space 80, and the abutting portion is positioned in contact with
the right side of the oil supply hole 130.
[0267] If the electromagnetic solenoid 75 changes over from an active state to an inactive
state, then the operating rod 76 moves leftwardly all at once by the spring 79 of
the electromagnetic solenoid 75. Following the leftward movement of the operating
rod 76, the push rod 74 is moved leftwardly by the spring 73 through the connection
pin 71 and the piston 72.
[0268] When the leftward movement of the push rod 74 and the operating rod 76 stops, the
sandwiched inner space 80 is formed again. Therefore, when the operating rod 76 stops,
the sandwiched inner space 80 communicating with the oil supply hole 130 can be filled
with oil.
[0269] FIG. 12 illustrates an example wherein the positional relationship between the sandwiched
inner space 80 and the oil supply hole 130 when the electromagnetic solenoid 75 is
in an inactive state is changed.
[0270] When the electromagnetic solenoid 75 is inactive, the oil supply hole 130 is offset
by a great amount to the push rod 74 side (right side) with respect to the sandwiched
inner space 80. Thus, the push rod 74 completely closes up the communication port
on the boundary between the oil supply hole 130 and the rod sliding hole 102.
[0271] In other words, when the electromagnetic solenoid 75 is in an inactive state, the
sandwiched inner space 80 is a closed space.
[0272] Accordingly, at an initial stage when the electromagnetic solenoid 75 operates, oil
in the sandwiched inner space 80 little flows out, and the damper function as an oil
damper is maintained. Thus, an impact or vibration by collision can be damped efficiently.
[0273] As the operating rod 76 moves rightwardly upon operation of the electromagnetic solenoid
75, also the sandwiched inner space 80 moves and is brought into communication with
the oil supply hole 130. Therefore, while the oil in the sandwiched inner space 80
gradually flows out through the oil supply hole 130, the sandwiched inner space 80
becomes smaller and the operating rod 76 approaches the push rod 74 until it is finally
abutted with the push rod 74.
[0274] Accordingly, since the operating rod 76 is abutted with the push rod 74 in such a
manner as to catch up the push rod 74 in a state in which the push rod 74 is moving
rightwardly, the impact upon abutment can be suppressed very low.
[0275] An operation state of the electromagnetic solenoid 75 when the operating rod 76 ends
the movement is indicated by an alternate long and two short dashes line in FIG. 12.
[0276] The abutting portion of the right end of the operating rod 76 with the left end of
the push rod 74 faces the oil supply hole 130. A configuration may be adopted wherein,
when the electromagnetic solenoid 75 changes over from an active state into an inactive
state, the push rod 74 decreases in speed and stops more quickly than the operating
rod 76. In this instance, the operating rod 76 moves at a higher speed than the push
rod 74, whereupon the sandwiched inner space 80 between the left end of the push rod
74 and the right end of the operating rod 76 gradually becomes larger. When the sandwiched
inner space 80 communicates with the oil supply hole 130, oil can be sucked into the
sandwiched inner space 80 through the oil supply hole 130. As a result, when the operating
rod 76 stops, the sandwiched inner space 80 is filled with the oil.
[0277] In the variable valve apparatus 70 of the present OHC type internal combustion engine
30, the accommodation cases 77 and 78 which accommodate the main body of the electromagnetic
solenoid 75 serving as a pressing force generation source attached to the wall face
of the left side wall 100L on which the ignition plug 49 of the cylinder head 33 is
provided in a projecting manner are provided at a position at which they do not overlap
with the ignition plug center axial line Cs directed by the ignition plug 49 as viewed
in the cylinder axial line direction as shown in FIGS. 7 and 14. Therefore, the electromagnetic
solenoid 75 can be disposed at a position at which it does not make an obstacle when
the ignition plug 49 is moved to be mounted or dismounted in the axial line direction
of the ignition plug center axial line Cs directed by the ignition plug 49 without
disposing the electromagnetic solenoid 75 away from the ignition plug 49. Therefore,
while miniaturization of the cylinder head 33 is achieved, the maintenance performance
of the ignition plug 49 can be maintained favorably.
[0278] Since the electromagnetic solenoid 75 is positioned on the head cover 34 side with
respect to the ignition plug 49 as shown in FIGS. 3 and 14, the maintenance space
around the ignition plug 49 can be assured readily.
[0279] Since the push rod 74 and the operating rod 76 which are pressing force transmission
members are provided for sliding movement on the cylinder head 33 as shown in FIG.
10, swelling of the electromagnetic solenoid 75, which provides pressing force to
the push rod 74 and the operating rod 76, to the head cover 34 side can be suppressed.
Consequently, increase in size of the cylinder head 33 and peripheral elements in
the cylinder axial line direction can be prevented.
[0280] Therefore, the variable valve apparatus 70 can be made suitable particularly for
the scooter type motorcycle 1 which is a saddle type vehicle and for which miniaturization
of the cylinder head 33 and peripheral elements is demanded.
[0281] As shown in FIGS. 3 and 14, in the electromagnetic solenoid 75, the plurality of
attachment arm portions 77pr, 77qr and 77rr are formed around the accommodation cases
77 and 78 so as to extend radially along the wall face of the left side wall 100L
of the cylinder head 33. The attachment arm portions 77pr, 77qr and 77rr are attached
only to the cylinder head 33. Therefore, it is possible to raise the rigidity of the
cylinder head 33 and further suppress swelling of the electromagnetic solenoid 75
to the head cover 34 side.
[0282] Further, the electromagnetic solenoid 75 is attached only to the cylinder head 33
but not to the head cover 34. Therefore, upon maintenance of the valve system in the
cylinder head 33, the head cover 34 can be removed without removing the electromagnetic
solenoid 75. Consequently, maintenance operation of the valve system can be carried
out readily.
[0283] Referring to FIGS. 3 and 14, from among the attachment arm portions 77pr, 77qr and
77rr of the electromagnetic solenoid 75, the attachment arm portion 77pr which extends
in a direction overlapping with the ignition plug center axial line Cs as viewed in
the cylinder axial line direction has the recessed portion 77d formed therein. The
recessed portion 77d is open toward the ignition plug 49 side in such a manner as
to cross but keep away from the ignition plug center axial line Cs. Therefore, when
the ignition plug 49 is moved in a direction of the ignition plug center axial line
Cs to be mounted or dismounted, the attachment arm portion 77pr does not make an obstacle
thanks to the recessed portion 77d. Consequently, a good maintenance performance of
the ignition plug 49 can be maintained favorably.
[0284] As shown in FIG. 14, the rib portions 103pr, 103qr and 103rr with which the attachment
arm portions 77pr, 77qr and 77rr extending from the periphery of the accommodation
cases 77 and 78 are abutted and the attachment boss portions 103p, 103q and 103r at
the end portions of the rib portions 103pr, 103qr and 103rr are formed in a projecting
manner on the cylinder head 33. Therefore, the electromagnetic solenoid 75 is retained
stably on the cylinder head 33 by the rib portions 103pr, 103qr and 103rr and the
attachment boss portions 103p, 103q and 103r.
[0285] Further, the attachment arm portions 77pr, 77qr and 77rr of the electromagnetic
solenoid 75 are abutted with and attached to the rib portions 103pr, 103qr and 103rr
and the attachment boss portions 103p, 103q and 103r. Therefore, the rib portions
103pr, 103qr and 103rr and the attachment boss portions 103p, 103q and 103r can be
maintained in a high rigidity state. Consequently, the electromagnetic solenoid 75
can be supported further firmly.
[0286] The accommodation cases 77 and 78 and the attachment arm portions 77pr, 77qr and
77rr of the electromagnetic solenoid 75 are made of a metal. Therefore, heat generated
in the accommodation cases 77 and 78 for the electromagnetic solenoid 75 can be transmitted
from the attachment arm portions 77pr, 77qr and 77rr to the rib portions 103pr, 103qr
and 103rr. Therefore, the heat radiation efficiency of the electromagnetic solenoid
75 can be improved.
[0287] Further, the rib portions 103pr, 103qr and 103rr and the attachment boss portions
103p, 103q and 103r are formed in a projecting manner on the wall face of the left
side wall 100L of the cylinder head 33. Therefore, those portions of the attachment
arm portions 77pr, 77qr and 77rr abutted by the rib portions 103pr, 103qr and 103rr
and attachment boss portions 103p, 103q and 103r which protrude from the abutting
face cooperate with the wall face of the left side wall 100L of the cylinder head
33 to form a space therebetween (refer to FIG. 8). As running wind enters the space,
the attachment arm portions 77pr, 77qr and 77rr can be cooled, and consequently, the
cooling effect can be raised.
[0288] As shown in FIGS. 10 and 14, the oil passage 133 is formed in the left side wall
100L, to which the electromagnetic solenoid 75 of the cylinder head 33 is attached,
in the neighborhood of the electromagnetic solenoid 75. Therefore, the electromagnetic
solenoid 75 can be cooled effectively by oil flowing in the oil passage 133.
[0289] The present OHC type internal combustion engine 30 is incorporated in the vehicle
body frame of the scooter type motorcycle 1, which is a saddle type vehicle, in a
posture in which the cylinder axial line Cc is tilted forward greatly to a position
proximate to a horizontal position. Further, the electromagnetic solenoid 75 which
is a pressing force generation source is attached to the wall face of the left side
wall 100L of the cylinder head 33 which is directed in the vehicle widthwise direction.
Furthermore, the outer side of the electromagnetic solenoid 75 in the vehicle widthwise
direction is covered with the connection pipe 6 which is part of the vehicle body
frame. Therefore, the electromagnetic solenoid 75 is disposed between the cylinder
head 33 and the connection pipe 6. Consequently, the electromagnetic solenoid 75 can
be protected effectively from an external factor by the cylinder head 33 and the connection
pipe 6.
[0290] As shown in FIG. 2, the water pump 150 is attached to the wall face of the right
side wall 100R on the opposite side to the wall face of the left side wall 100L to
which the electromagnetic solenoid 75 of the cylinder head 33 is attached. Therefore,
the electromagnetic solenoid 75 and the water pump 150 which are heavy articles are
attached in a distributed manner on the opposite side wall faces directed in the vehicle
widthwise direction of the cylinder head 33 so that they do not interfere with each
other. Consequently, the weight balance around the cylinder head 33 can be improved.
Further, also where both of the electromagnetic solenoid 75 and the water pump 150
are attached to the cylinder head 33, the maintenance performance of the ignition
plug 49 can be assured favorably by attaching the ignition plug 49 in such a manner
as illustrated in FIG. 3 to the left side wall 100L to which the electromagnetic solenoid
75 is attached.
[0291] As shown in FIG. 2, the breather chamber 34b is provided on the inner side of the
head cover 34, and the exit portion 34c of the breather chamber 34b is formed on the
outer wall face of the head cover 34 such that the opening thereof is directed to
the water pump 150 side in the vehicle widthwise direction. Therefore, the breather
hose 146 connected to the exit portion 34c of the breather chamber 34b of the head
cover 34 and extending to the water pump 150 side does not interfere with the electromagnetic
solenoid 75 on the opposite side. Also it can be avoided readily for the breather
hose 146 to interfere with the water pump 150 provided on the crankcase 31 side with
respect to the electromagnetic solenoid 75.
[0292] In the embodiment described above, the oil supply hole 130 with respect to the sandwiched
inner space 80 when the electromagnetic solenoid 75 is in an inactive state is offset
to the push rod 74 side (right side). However, the oil supply hole 130 with respect
to the sandwiched inner space 80 may be offset alternatively to the operating rod
76 side (left side).
[0293] However, it is necessary to employ a configuration in which, when the electromagnetic
solenoid 75 is in an inactive state, the oil supply hole 130 is in a communicated
state with the sandwiched inner space 80 and oil is supplied into the sandwiched inner
space 80.
[0294] In such a configuration as just described, when the electromagnetic solenoid 75 is
in an inactive state, the right end portion of the operating rod 76 closes part of
the communication hole on the boundary between the oil supply hole 130 and the rod
sliding hole 102. Therefore, the sandwiched inner space 80 is in a state proximate
to that of a closed space.
[0295] Accordingly, at an initial stage when the electromagnetic solenoid 75 is rendered
operative to project the operating rod 76, flowing out of the oil in the sandwiched
inner space 80 from the oil supply hole 130 is suppressed. Therefore, the damper function
as an oil damper for pressing the push rod 74 through the oil in the sandwiched inner
space 80 by the operating rod 76 can be enhanced, and an impact and vibration by collision
can be buffered.
[0296] In the variable valve apparatus 70 for the present OHC type internal combustion engine
30, the connection pin 71 is disposed between the rocker arm shaft insertion holes
57h and 58h for the first and second rocker arms 57 and 58 and the action side end
portions 57vv and 58vv which act on the first and second intake valves 61 and 62 as
shown in FIG. 6. Therefore, the connection pin 71 can be provided not at a position
swollen by a great amount to the head cover 34 side from the intake rocker arm shaft
55 but at a position nearer to the intake rocker arm shaft 55 in the cylinder axial
line direction on the crankcase 31 side. Therefore, there is no necessity to make
the first and second intake rocker arms 57 and 58 themselves swell to the head cover
34 side to increase the size of them. In addition, increase in size of the cylinder
head 33 and the head cover 34 can be avoided.
[0297] Further, the rod sliding hole 102 which is a pressing force transmission member sliding
hole is formed on the cylinder head 33 at the position at which it overlaps with the
intake rocker arm shaft supporting hole 122h in the cylinder axial line direction
between the stud bolt fastening hole 125 and the rocker arm shaft supporting hole
122h as shown in FIG. 10. Therefore, the push rod 74 and the operating rod 76 which
are pressing force transmission members can be disposed compactly making use of the
space between the stud bolt fastening hole 125 and the intake rocker arm shaft supporting
hole 122h. Further, the push rod 74 and the operating rod 76 which are pressing force
transmission members are provided at the position at which they overlap with the intake
rocker arm shaft 55 in the cylinder axial line direction. Therefore, the cylinder
head 33 can be miniaturized in the cylinder axial line direction, and increase in
size of the cylinder head 33 and the head cover 34 can be avoided more and more.
[0298] Specifically, as the OHC type internal combustion engine 30 to be incorporated in
the present scooter type motorcycle 1 which is a saddle type vehicle in which it is
difficult to assure a space, the OHC type internal combustion engine of the present
invention which avoids increase in size of the cylinder head 33 and associated elements
can be suitably applied.
[0299] It is to be noted that, while, in the present embodiment, the push rod 74 and the
operating rod 76 as pressing force transmission members are formed as separate members,
also it is possible in the present invention to apply them as a single rod.
[0300] Further, the adjustment screws 57t and 58t for adjusting the abutting position with
the first and second intake valves 61 and 62 are screwed in the action side end portions
57vv and 58vv of the first and second intake rocker arms 57 and 58 as shown in FIG.
6. Further, the axial line Cp of the connection pin 71 is disposed between the head
side end portions 57tt and 58tt of the adjustment screws 57t and 58t and the axial
line Cr of the rocker arm shaft insertion holes 57h and 58h in the cylinder axial
line direction. Therefore, the intake rocker arm shaft 55, connection pin 71 and adjustment
screws 57t and 58t can be juxtaposed on a substantially straight line. Consequently,
the valve side arm portions 57v and 58v of the first and second intake rocker arms
57 and 58 from the rocker arm shaft insertion holes 57h and 58h to the action side
end portions 57vv and 58vv which act on the first and second intake valves 61 and
62 can be formed in a substantially liner shape. Therefore, the first and second intake
rocker arms 57 and 58 can be miniaturized in a high space efficiency.
[0301] Further, the portions of the first and second intake rocker arms 57 and 58 in which
the connection pin 71 is fitted for movement are formed with a thickness increased
by an amount by which the connection pin 71 is fitted and supported. Therefore, the
rigidity of the valve side arm portions 57v and 58v from the rocker arm shaft insertion
holes 57h and 58h to the action side end portions 57vv and 58vv which act on the first
and second intake valves 61 and 62 can be raised.
[0302] The connection pin 71 and the push rod 74 and operating rod 76 which are pressing
force transmission members are provided on the crankcase 31 side with respect to the
mating face 100t between the cylinder head 33 and the head cover 34 as shown in FIG.
6. Therefore, the intake rocker arm shaft 55, connection pin 71 and adjustment screws
57t and 58t are juxtaposed on a straight line, and the adjustment screws 57t and 58t
are positioned in the proximity of the mating face 100t between the cylinder head
33 and the head cover 34. Consequently, an adjustment operation of the adjustment
screws 57t and 58t can be carried out readily.
[0303] Especially, the connection pin 71, push rod 74 and operating rod 76 are positioned
on the crankcase 31 side with respect to the head side end portions 57tt and 58tt
of the adjustment screws 57t and 58t. Therefore, an adjustment operation by the adjustment
screws 57t and 58t can be carried out more readily.
[0304] The push rod 74 and the operating rod 76 neighbor with the stud bolts 180 as shown
in FIGS. 6 and 7. Therefore, the stud bolt fastening hole 125 and the rod sliding
hole 102 which is a pressing force transmission member sliding hole 102 of the cylinder
head 33 can be positioned as near as possible to the intake rocker arm shaft supporting
hole 122h. Consequently, miniaturization of the cylinder head 33 can be anticipated.
[0305] The axial line Cd of the push rod 74 and the operating rod 76 is positioned on the
crankcase 31 side with respect to the axial line Cp of the connection pin 71 as shown
in FIG. 6. Therefore, the electromagnetic solenoid 75 which presses the push rod 74
and the operating rod 76 can be disposed near to the crankcase 31 side. Consequently,
the swelling amount of the electromagnetic solenoid 75 to the head cover 34 side in
the cylinder axial line direction can be reduced.
[0306] Further, the axial line Cd of the push rod 74 and the operating rod 76 is positioned
on the intake rocker arm shaft 55 side with respect to the axial line Cp of the connection
pin 71 as shown in FIG. 6. Therefore, a configuration wherein, while the push rod
74 and the operating rod 76 avoid interference with the stud bolts 180, they press
the connection pin 71 efficiently can be implemented.
[0307] The electromagnetic solenoid 75 is fixedly secured only to the cylinder head 33 as
shown in FIGS. 3 and 14. Therefore, the shape of the mating face between the cylinder
head 33 and the head cover 34 can be simplified. Besides, since the necessity to fix
the electromagnetic solenoid 75 to the head cover 34 side is eliminated, also simplification
of the head cover 34 can be achieved.
[0308] Further, upon maintenance of the valve system in the cylinder head 33, the head cover
34 can be removed without removing the electromagnetic solenoid 75. Therefore, the
maintenance operation of the valve system can be facilitated.
[0309] A variable valve apparatus for an OHC type internal combustion engine is provided
and which includes a crankcase (31), a cylinder block (32) and a cylinder head (33)
placed in order on the crankcase (31) and fastened together by a plurality of stud
bolts (180) extending through the cylinder block (32) and the cylinder head (33) in
a cylinder axial line direction, a plurality of rocker arms (57, 58) arrayed and supported
for rocking motion in a mutually neighboring relationship on a rocker arm shaft (55)
in the inside of the cylinder head (33) and operable in an interlocking relationship
with engine valves (61, 62), and a head cover (34) placed on the cylinder head (33)
to cover the cylinder head (33). The variable valve apparatus comprises: a connection
pin (71) fitted for movement in an axial direction of the rocker arm shaft (55) in
the rocker arms (57, 58) positioned adjacent each other and movable between a connection
position at which the connection pin (71) connects the rocker arms (57, 58) positioned
adjacent each other to each other for integral rocking motion and a disconnection
position at which the connection pin (71) disconnects the rocker arms (57, 58) from
each other to allow independent rocking motion of each of the rocker arms (57, 58);
and a pressing force transmission member (74, 76) configured to transmit pressing
force of a pressing force generation source (75) disposed outside the cylinder head
(33) to the connection pin (71) to move the connection pin (71). The pressing force
generation source (75) being attached to a wall face (100L) of the cylinder head (33)
on which an ignition plug (49) is provided in a projecting manner. An accommodation
case (77, 78) which accommodates a main body of the pressing force generation source
(75) therein being provided at a position at which the accommodation case (77, 78)
does not overlap with an ignition plug center axial line (Cs), which is directed by
the ignition plug (49), as viewed in the cylinder axial line direction.
[0310] The pressing force generation source (75) can be positioned on the head cover (34)
side with respect to the ignition plug (49).
[0311] The pressing force transmission member (74, 76) can be provided for sliding movement
on the cylinder head (33).
[0312] The pressing force generation source (75) can have a plurality of attachment arm
portions (77pr, 77qr, 77rr) formed around the accommodation case (77, 78) so as to
extend radially along the wall face (100L) of the cylinder head (33), and the attachment
arm portions (77pr, 77qr, 77rr) can be attached only to the cylinder head (33).
[0313] From among the attachment arm portions (77pr, 77qr, 77rr), the attachment arm portion
(77pr) which extends in a direction overlapping with the ignition plug center axial
line (Cs) as viewed in the cylinder axial line direction can have a recessed portion
(77d) formed thereon so as to be open toward the ignition plug (49) side in such a
manner that the recessed portion (77d) crosses but keeps away from the ignition plug
center axial line (Cs).
[0314] On the cylinder head (33), rib portions (103pr, 103qr, 103rr) with which the attachment
arm portions (77pr, 77qr, 77rr) extending from the periphery of the accommodation
case (77, 78) can be abutted and attachment boss portions (103p, 103q, 103r) at end
portions of the rib portions (103pr, 103qr, 103rr) can be formed in a projecting manner,
and the attachment arm portions (77pr, 77qr, 77rr) can be attached to the attachment
boss portions (103p, 103q, 103r).
[0315] The accommodation case (77, 78) and the attachment arm portions (77pr, 77qr, 77rr)
of the pressing force generation source (75) can be made of a metal.
[0316] On the wall face (100L) to which the pressing force generation source (75) of the
cylinder head (33) is attached, an oil passage (133) can be formed in the proximity
of the pressing force generation source (75).
[0317] The OHC type internal combustion engine (30) can be mounted on a vehicle body frame
of a saddle type vehicle (1) in a posture in which a cylinder axial line (Cc) is tilted
forward greatly to a position proximate to a horizontal position. The pressing force
generation source (75) can be attached to the side wall face (100L) of the cylinder
head (33) directed in the vehicle widthwise direction. The pressing force generation
source (75) can be covered on the outer sides thereof in the vehicle widthwise direction
with part (6) of the vehicle body frame.
[0318] A water pump (150) can be attached to a side wall face (100R) of the cylinder head
(33) on the opposite side to the side wall face (100L) to which the pressing force
generation source (75) is attached.
[0319] The water pump (150) can be disposed on the crankcase side with respect to the pressing
force generation source (75) in the cylinder axial line direction. A breather chamber
(34b) can be provided on the inner side of the head cover (34). An exit portion (34c)
of the breather chamber (34b) can be formed on an outer wall face of the head cover
(34) such that an opening thereof is directed to the water pump (150) side in the
vehicle widthwise direction.
[Description of Reference Symbols]
[0320] 1 ... Scooter type motorcycle, 4 ... Floor pipe, 5 ... Main pipe, 6 ... Connection
pipe, 20 ... Power unit, 30 ... Internal combustion engine, 31 ... Crankcase, 32 ...
Cylinder block, 33 ... Cylinder head, 34 ... Head cover, 34b ... Breather chamber,
49 ... Ignition plug, 50 ... Valve mechanism, 54 ... Camshaft, 55 ... Intake rocker
arm shaft, 56 ... Exhaust rocker arm shaft, 57 ... First intake rocker arm, 57t ...
Adjustment screw, 57h ... Rocker arm shaft insertion hole, 58 ... Second intake rocker
arm, 58t ... Adjustment screw, 58h ... Rocker arm shaft insertion hole, 59 ... Exhaust
rocker arm, 61 ... First intake valve, 62 ... Second intake valve, 63 ... First exhaust
valve, 64 ... Second exhaust valve, 70 ... Variable valve apparatus, 71 ... Connection
pin, 72 ... Disconnection piston, 74 ... Push rod, 75 ... Electromagnetic solenoid,
76 ... Operating rod, 77 ... Accommodation case, 77a ... Cylindrical portion, 77b
... Bottom wall portion, 77P, 77q, 77r ... Attachment boss portion, 77pr, 77qr, 77rr
... Attachment arm portion, 77d ... Recessed portion, 80 ... Sandwiched inner space,
100 ... Outer peripheral wall, 100L... Left side wall, 100R... Right side wall, 101
... Ignition plug mounting hole, 102 ... Rod sliding hole, 103p, 103q, 103r ... Attachment
boss portion, 103pr, 103qr, 103rr ... Rib portion, 104p, 104q, 104r ... Bolt, 110
... Inner wall, 112 ... Intake rocker arm shaft supporting portion, 112h ... Intake
rocker arm shaft supporting hole, 113 ... Exhaust rocker arm shaft supporting portion,
113h ... Exhaust rocker arm shaft supporting hole, 115, 116 ... Stud bolt fastening
hole, 122 ... Intake rocker arm shaft supporting portion, 122h ... Intake rocker arm
shaft supporting hole, 125, 126 ... Stud bolt fastening hole, 130 ... Oil supply hole,
131, 132, 133 ... Oil passage, 135 ... Oil guide groove, 136 ... Rib, 140, 141 ...
Reinforcement plate, 146 ... Breather hose, 150 ... Water pump, 180 ... Stud bolt,
181 ... Hexagonal nut.