TECHNICAL FIELD
[0001] The present invention relates to an engine valve device and technology allowing variable
motion of the engine valve device.
BACKGROUND ART
[0002] FIG. 7 is a sectional side view showing a structure of a known engine valve device.
FIG. 8 is a circuit diagram showing a configuration of a fluid circuit of the engine
valve device shown in FIG. 7. As shown in FIG. 7, an engine valve device 100 is configured
to maintain an open state of an intake valve 103 by a fluid actuator 101 via a rocker
arm 102. As shown in FIG. 8, this engine valve device 100 includes the fluid actuator
101 that follows the rocker arm 102, a direction control valve 105 that stops a flow
of fluid from fluid actuator 101 at a predetermined timing, and a fluid source that
supplies fluid to the direction control valve 105. The direction control valve 105
stops the flow of fluid from the fluid actuator 101 at the predetermined timing, and
the fluid actuator 101 acts on the rocker arm 102. Therefore, the engine valve device
100 can maintain the open state of the intake valve 103. The fluid source used as
such usage is, for example shown in FIG. 8, a part of a lubrication unit 107, which
is attached to the engine to supply lubricating oil to the engine, and is capable
of supplying pressurized oil of a pressure from about 210 KPa to 620 KPa. On the other
hand, a pump may be provided separately from the lubrication unit 107 attached to
the engine to supply pressurized oil of a pressure from 10 MPa to 35 MPa to the direction
control valve 105 (for example, see Patent Document 1).
[0003] Patent Document 1: Japanese Patent Application Laid-Open No.
2003-328715
DISCLOSURE OF INVENTION
PROBLEM TO BE SOLVED BY THE INVENTION
[0004] However, if the part of lubrication unit 107 attached to the engine as the fluid
source supplies pressurized oil of the pressure from 210 KPa to 620 KPa to the direction
control valve 105, a piston 106 cannot follow an open-close motion of the intake valve
103 when the engine is at a high revolution, for example, over 1000 rpm. Therefore,
the piston 106 can not reach to a predetermined position and can not put the intake
valve into the open state at a desired amount of opening. On the other hand, if the
pump is provided separately from the lubrication unit 107 attached to the engine to
supply pressurized oil of a pressure from 10 MPa to 35 MPa, it is subject to a considerable
increase in cost as well as the engine becomes larger. Also, because the lubrication
unit 107 attached to the engine supplies and discharges pressurized oil every time
the fluid actuator 101 acts on, an energy loss becomes tremendously large.
[0005] The present invention is made in view of the above problems and an object of the
present invention is to provide an engine valve device which is capable of following
a high revolution of an engine and of highly efficient operating although the engine
valve device is configured to vary a motion, utilizing a part of a lubricating oil
unit attached to the engine as an oil source.
MEANS FOR SOLVING PROBLEM
[0006] To solve the problem and achieve the above object, an engine valve device according
to the present invention includes a cam which rotates by engaging with a crankshaft,
a rocker arm which follows a movement of the cam, and an intake valve which opens
and closes an intake port by interacting the rocker arm and a spring. The engine valve
device comprises: a piston which is movable in a same direction as the intake valve;
a cylinder which houses the piston such that the piston is movable inside the cylinder;
a hydraulic actuator including the piston and the cylinder; a hydraulic pipe line
which communicates with a pressure chamber formed by the piston and the cylinder;
an accumulation unit which accumulates hydraulic oil flowed out from the pressure
chamber via the hydraulic pipe line; and an electromagnetic on-off valve which controls
a flow of the hydraulic oil between the pressure chamber and the accumulation unit.
The hydraulic actuator, the hydraulic pipe line, the accumulation unit, and the electromagnetic
on-off valve make up a hydraulic circuit. The electromagnetic on-off valve is arranged
on the hydraulic pipe line between the hydraulic actuator and the accumulation unit.
[0007] Also, according to the present invention, an engine valve device includes a cam which
rotates by engaging with a crankshaft, a rocker arm which follows a movement of the
cam, an intake valve which opens or closes an intake port by interacting the rocker
arm and a spring, and a hydraulic circuit. The hydraulic circuit includes: a hydraulic
actuator which is activated by an open and close motion of the intake valve, the hydraulic
actuator stopping a closing motion of the intake valve in an open state when hydraulic
oil is sealed in a pressure chamber; an accumulation unit which accumulates the hydraulic
oil flowed out from the pressure chamber of the hydraulic actuator when the intake
valve moves to close, and which provides the hydraulic oil to the pressure chamber
of the hydraulic actuator when the intake valve moves to open; and an electromagnetic
on-off valve which controls a flow of the hydraulic oil from the hydraulic actuator
to the accumulation unit. The electromagnetic on-off valve is arranged between the
hydraulic actuator and the accumulation unit.
[0008] Also, according to the present invention, the invention described above further comprises
a hydraulic oil supply unit which provides the hydraulic oil to the hydraulic circuit.
[0009] Also, according to the present invention, in the invention described above, the hydraulic
oil supply unit is a lubrication unit which provides lubricating oil to an engine
and is attached to the engine.
[0010] Also, according to the present invention, the invention described above further comprises
an auxiliary pipe line which allows the flow of the hydraulic oil from the pressure
chamber of the hydraulic actuator to the accumulation unit. The auxiliary pipe line
includes a port which opens when the piston of the hydraulic actuator comes to a predetermined
interval, the piston of the hydraulic actuator follows the intake valve moving to
a closing direction.
[0011] Also, according to the present invention, the invention described above further comprises
a check valve which supplies the hydraulic oil from the hydraulic oil supply unit
to the hydraulic circuit only if an oil pressure of the hydraulic circuit is lower
than that of the hydraulic oil supply unit, and the check valve is arranged between
the hydraulic oil supply unit and the hydraulic circuit.
[0012] Also, according to the present invention, in the invention described above, the pressure
chamber of the hydraulic actuator is configured to cushion a shock when the intake
valve closes.
[0013] Also, according to the present invention, the invention described above further comprises:
a push rod which transmits motion from the cam to the rocker arm, the push rod being
disposed between the cam and the rocker arm; and a biasing unit which biases the rocker
arm to tightly contact with the push rod.
EFFECT OF THE INVENTION
[0014] The engine valve device according to the present invention includes the hydraulic
circuit including the accumulation unit which accumulates hydraulic oil flowed out
from the pressure chamber of the hydraulic actuator when the intake valve moves to
close, and provides hydraulic oil to the pressure chamber of the hydraulic actuator
when the intake valve moves to open, and the electromagnetic on-off valve which controls
a flow of the hydraulic oil from the hydraulic actuator to the accumulation unit.
The electromagnetic on-off valve is arranged between the hydraulic actuator and the
accumulation unit. Accordingly, to precisely make the intake valve an open state,
the engine valve device can follow a high revolution of the engine and be efficiently
operated.
[0015] Also, in the engine valve device according to the present invention, the lubrication
unit, which is attached to the engine and provides lubricating oil to the engine,
provides hydraulic oil to the hydraulic circuit. Accordingly, there is no need to
provide an oil pump separately from the lubrication unit attached to the engine, there
is no need to grow in size, and an increase in cost is suppressed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016]
FIG. 1 is a schematic view of an engine valve device according to an embodiment of
the present invention;
FIG. 2A is a view showing a behavior of the engine valve device shown in FIG. 1 and
showing a close state of an intake valve;
FIG. 2B is a view showing a behavior of the engine valve device shown in FIG. 1 and
showing a full open state of the intake valve;
FIG. 2C is a view showing a behavior of the engine valve device shown in FIG. 1 and
showing a close starting state of the intake valve;
FIG. 2D is a view showing a behavior of the engine valve device shown in FIG. 1 and
showing a state in which the intake valve is closed to a predetermined gate opening;
FIG. 2E is a view showing a behavior of the engine valve device shown in FIG. 1 and
showing a full close state of the intake valve;
FIG. 3 is a view showing a hydraulic circuit of the engine valve device shown in FIG.
1;
FIG. 4 is a view showing a relation between a cam rotating angle and an amount of
valve lift for an intake stroke of the engine valve device shown in FIG. 1;
FIG. 5 is a flowchart showing control of the engine valve device shown in FIG. 1;
FIG. 6 is a timing chart showing a control timing of the engine valve device shown
in FIG. 1;
FIG. 7 is a sectional side view showing a structure of a known engine valve device;
FIG. 8 is a view showing a configuration of a fluid circuit of the engine valve device
shown in FIG. 7;
DESCRIPTION OF THE NUMERALS
[0017]
- 1
- Engine valve device
- 2
- Intake port
- 3
- Intake valve
- 3a
- Valve portion
- 3b
- Stem
- 4
- Valve spring
- 5
- Crosshead
- 9
- Rocker arm
- 9a
- Pressing portion
- 9b
- Action portion
- 9c
- Groove
- 13
- Push rod
- 14
- Tappet arm
- 15
- Return spring
- 18
- Cam
- 20
- Hydraulic actuator
- 21
- Block
- 21a
- Concave portion
- 21b
- First pipe line
- 21c
- Second pipe line
- 21d
- Supply discharge pipe line
- 21e
- Flow pipe line
- 22
- Cylinder portion
- 22a
- Small diameter chamber
- 22b
- Large diameter chamber
- 22b1
- Oil groove
- 23
- Piston
- 23a
- Piston portion
- 23b
- Buffering portion
- 23b1
- Longitudinal groove
- 23c
- Rod portion
- 24
- Gap sensor
- 30
- Electromagnetic on-off valve
- 40
- Engine control unit (ECU)
- 50
- Accumulator
- 52
- Pressure accumulating portion
- 55
- Cylinder
- 56
- Plunger
- 57
- Compression spring
- 60
- Hydraulic circuit
- 61
- Lubrication unit attached to engine
- 62
- Check valve
- 63
- Relief valve
- 64
- Oil pan
- CH
- Cylinder head
BEST MODE FOR CARRYING OUT THE INVENTION
[0018] Referring to attached figures, an embodiment of an engine valve device according
to the present invention is described below. Meanwhile, the present invention is not
limited by the embodiment.
[0019] FIG. 1 is a schematic view of an engine valve device according to an embodiment of
the present invention; FIG. 2 is a view showing a behavior of the engine valve device
shown in FIG. 1; FIG. 3 is a view showing a hydraulic circuit of the engine valve
device shown in FIG. 1; and FIG. 4 is a view showing a relationship between a cam
rotating angle and an amount of valve lift for an intake stroke of the engine valve
device shown in FIG. 1; FIG. 5 is a flowchart showing control of the engine valve
device shown in FIG. 1; FIG. 6 is a timing chart showing control timing of the engine
valve device shown in FIG. 1
[0020] An engine valve device 1 according to an embodiment of the present invention is applied
to an engine valve device of a four-cycle diesel engine.
[0021] The diesel engine includes a cylinder block and a cylinder head CH. The cylinder
block is provided with a cylindrically shaped cylinder which allows an engine piston
EP slides in up-and-down direction.
[0022] The cylinder head is provides with a pair of intake ports 2 which are in communication
with an outside of the cylinder and a pair of exhaust ports which is not shown in
the figure. At each intake port 2, an intake valve 3 is provided such that the intake
valve 3 closes or opens the intake port 2 by moving up and down with respect to FIG.
1. At each exhaust port, an exhaust valve, not shown in the figure, is provided such
that the exhaust valve closes or opens the exhaust port by moving up and down.
[0023] The intake valve 3 and the exhaust valve are poppet valves which are formed in an
umbrella shape, and include valve portions (umbrella shaped portion) 3a that close
the intake port 2 and the exhaust port and stems (rod shaped portion) 3b that slides
through the cylinder head CH.
[0024] The stem 3b of the intake valve 3 which is in communication with the intake port
2 is provided with a valve spring 4, and the valve portion 3a of the intake valve
3 is biased to close the intake port 2. In a similar way, the stem of the exhaust
valve which is in communication with the exhaust port is provided with a valve spring,
not shown in the figure, and the valve portion of the exhaust valve is biased to close
the exhaust port.
[0025] Above the cylinder head CH, a crosshead 5 which has a side view of a T shape and
pushes the ends of stems of the pair of the intake valves 3 at the same time is provides.
The crosshead 5 is guided by a shaft 6 provided to be placed parallel to a moving
direction of the intake valve 3 and the exhaust valve, and is allowed to move up and
down with respect to FIG. 1. Therefore, the crosshead 5 pushes the ends of the stems
of the intake valves 3 to open the intake valves 3 against biasing forces of the valve
springs 4 when the crosshead 5 moves down.
[0026] One side of arm 5a of the crosshead 5 (left side arm in FIG. 1) is provided with
an adjustable screw 7 such that the crosshead 5 closely contacts with the intake valve
3. The adjustable screw 7 can be screwed with respect to the crosshead 5 to adjust
a clearance of one of the pear of the intake valves 3 (left side intake valve in FIG.
1). For example, it is adjustable such that one of the intake valves 3 opens the intake
port 2 at the same time the other of the intake valves 3 opens the intake port 2.
A locknut 8 is threadably mounted on the adjustable screw 7 to prevent from loosening
by closely sticking the locknut 8 to the crosshead 5 after adjusting.
[0027] A rocker arm 9 is provided above the crosshead 5 as shown in FIG. 1. The rocker arm
9 is rotatable around a rocker shaft 10 as an axis. The rocker arm 9 includes a pressing
portion 9a which pushes the crosshead 5 on an end portion (left side portion in FIG.
1) and an action portion 9b on the other end portion. The pressing portion 9a of the
rocker arm 9 is allowed to push around a central portion of the crosshead 5. Thus,
when the rocker arm 9 rotates counterclockwise with respect to FIG. 1, the pressing
portion 9a of the rocker arm 9 pushes the crosshead 5, and the intake valve 3 opens
the intake port 2. In contrast, when the rocker arm 9 rotates clockwise with respect
to FIG. 1, the intake valve 3 closes the intake port 2 by the biasing force of the
valve spring 4 and moves up the crosshead 5. On a central portion of the pressing
portion 9a, a groove 9c which has a planar view of a U shape is formed.
[0028] An adjust screw 11 is threadably mounted on the action portion 9b of the rocker arm
9 to adjust a clearance between the pressing portion 9a and the crosshead 5. The adjust
screw 11 includes a hemisphere portion on an end portion and a male screw on the other
end portion. A locknut 12 is threadably mounted on the adjust screw 11 which is threadably
mounted on the other end portion of the rocker arm 9. The adjust screw 11 is allowed
to prevent from loosening by closely sticking the locknut 12 to the rocker arm 9.
[0029] The end portion of hemisphere of the adjust screw 11 is housed in an end portion
of a push rod 13. The end portion of the push rod 13 is provided with a concave portion
13a of hemisphere and has a capacity of housing the end portion of hemisphere of the
adjust screw 11.
[0030] The push rod 13 rotates the rocker arm 9 counterclockwise with respect to FIG. 1.
As shown in FIG.2, the other end portion 13b of the push rod 13 is housed in a push
rod housing 14a provided above an arm portion of a tappet arm 14.
[0031] As shown in FIG. 1, a return spring 15 is tacked between the action portion 9b of
the rocker arm 9 and the cylinder head CH. The return spring 15 pushes the rocker
arm 9 clockwise with respect to FIG. 1, and is capable of maintaining to house the
end portion of the adjust screw 11 in the concave portion 13a of the push rod 13.
Meanwhile, the return spring 15 is to push the rocker arm 9 clockwise with respect
to FIG. 1, and the return spring 15 is replaced by a torsion coil spring which is
wound around the rocker shaft 10. In this case, an end of the coil spring is fixed
to the rocker arm 9, and the other end is fixed to the cylinder head CH.
[0032] As shown in FIG. 2, a tappet arm 14 is rotatably attached to a tappet shaft as an
axis. Thus, when the tappet arm 14 rotates clockwise with respect to FIG. 2, the tappet
arm 14 pushes up the push rod 13 and causes the rocker arm 9 to rotate counterclockwise
with respect to FIG. 2.
[0033] Below an arm portion of the tappet arm 14, a roller follower 17 is rotatably attached.
Below the roller follower 17, a cam 18 is rotatably provided to allow a rolling contact
with the roller follower 17. The cam 18 rotates by engaging with a crankshaft, not
shown in the figure, of the engine. The cam 18 moves (lifts) the intake valve 3 via
the tappet arm 14, the push rod 13, the rocker arm 9, and the crosshead 5, thereby,
allowing the intake port 2 to open. Thus, an opening timing of the intake port 2 and
a valve lift amount of the intake valve 3 are controlled by a surface configuration
(cam profile) of the cam 18. The valve lift amount describes an action toward an open
direction at a closing time of 0 as a lift, and takes a positive value at the moment.
[0034] The crankshaft is connected to the other end portion of a con-rod of which an end
portion is connected to the engine piston EP sliding in the cylinder. Thus, the intake
valve 3 can be opened and closed in the intake stroke, and the intake valve 3 can
be closed in a compression stroke, a combustion stroke, and an exhaust stroke.
[0035] As shown in FIG. 1, an hydraulic actuator 20 is provided above the crosshead 5. The
hydraulic actuator 20 is arranged such that a tip of a rod portion 23c of a piston
23 contacts with the crosshead 5 and is capable of engaging with a movement of the
crosshead 5. The hydraulic actuator 20 pushes the crosshead 5 at a predetermined timing
and maintains an open state of the intake valve 3 regardless of movements of the cam
18, the tappet arm 14, the push rod 13, and the rocker arm 9.
[0036] The hydraulic actuator 20 applied to the embodiment is a single acting type. In the
hydraulic actuator 20, a cylinder portion 22 is integrally formed with a block 21,
and an electromagnetic on-off valve 30 can be housed to be attached.
[0037] A supply discharge pipe line 21d which communicates with an output port 30b of the
electromagnetic on-off valve 30 is formed on the block 21. Also, a first pipe line
21b which communicates with an output port 50a of an accumulator 50, which will be
explained later in detail, is formed. The first pipe line 21b communicates with an
intake port 30a of the electromagnetic on-off valve 30 and a flow pipe line 21e, which
will be explained later in detail, by a second pipe line 21c.
[0038] The cylinder portion 22 includes a small diameter chamber 22a and a large diameter
chamber 22b, which constitute a pressure chamber and have cylindrical shapes. One
end of the large diameter chamber 22b is opened to accept an insertion of the piston
23, and closed by the piston 23. The other end of the large diameter chamber 22b is
formed such that the small diameter chamber 22a coincides and communicates with an
axis of the large diameter chamber 22b. The small diameter chamber 22a communicates
with the supply discharge pipe line 21d. A step 22c is formed on a border of the large
diameter chamber 22b and the small diameter chamber 22a.
[0039] An oil groove 22b1 is formed on a predetermined section of the large diameter chamber
22b. The flow pipe line 21e which communicates with a second pipe line 21c is formed
on the oil groove 22b1.
[0040] The cylinder portion 22 houses the piston 23 which slides in an axial direction of
the large diameter chamber 22b and the small diameter chamber 22a (up and down direction
with respect to FIG. 1). The piston 23 includes a piston portion 23a, a buffering
portion 23b, and a rod portion 23c. The piston portion 23a is a portion which slides
in the large diameter chamber 22b of the cylinder portion 22. The buffering portion
23b is a portion which is housed in the small diameter chamber 22a of the cylinder
portion 22, and is provided to one end of axial direction (above the piston portion
in FIG. 1) of the piston portion 23a. The buffering portion 23b is capable of, by
interaction between the buffering portion 23b and the small diameter chamber 22a of
the cylinder portion 22, cushioning a shock caused when the intake valve 3 closes.
Within the meaning, the pressure chamber is configured to cushion the shock caused
when the intake valve 3 is closed.
[0041] To be more specific, the buffering portion 23b includes a buffering shape which cushions
the shock caused when the intake valve 3 is closed (when the intake valve 3 seats).
The buffering shape is, for example, a plurality of longitudinal grooves 23b1 (four
longitudinal grooves in this embodiment) which are formed from a circumferential root
to a tip of the buffering portion 23b. When the buffering portion 23b is housed into
the small diameter chamber 22a, the shock caused when the buffering portion 23b is
housed into the small diameter chamber 22a is cushioned by flowing out hydraulic oil
accumulated in an upper end corner portion of the large diameter chamber 22b via the
longitudinal grooves 23b1. Accordingly, the shock caused when the intake valve 3 engaging
the piston 23 of the hydraulic actuator 20 is closed is cushioned, and a valve portion
3a is protected from a crash by the shock caused when the valve portion 3a seats.
[0042] Meanwhile, the buffering shape is not limited to the longitudinal groove 23b1, and
may be formed in a tapered shape which gradually tapers from the circumferential root
to the tip of the buffering portion 23b. Also, the buffering shape may be formed in
a tapered shape in which the small diameter chamber 22a gradually gets thick from
a bottom portion to the large diameter chamber 22b. The rod portion 23c is a portion
which extends outside of the cylinder portion 22, and is provided to an end opposite
to the buffering portion 23b in axial direction of the piston portion 23a (below the
piston portion 23a with respect to FIG. 1). The rod portion 23c is formed in a taper
shape which gradually tapers from the root to the tip. The rod portion 23c is capable
of pushing the crosshead 5 without interference of the rocker arm 9 by inserting the
groove 9c formed on the pressing portion 9a of the rocker arm 9. Thus, the rod portion
23c is capable of pushing the crosshead 5 separately from the rocker arm 9.
[0043] A gap sensor (clearance measurement means) 24 is provided on a side of the rod portion
23c of the piston 23. The gap sensor 24 measures a clearance between the rod portion
23c and the gap sensor 24, and is connected to an engine control unit (ECU) 40. The
gap sensor 24 is capable of measuring the clearance, for example, by measuring a current
surge. The engine control unit 40 is capable of monitoring an action of the hydraulic
actuator 20 by monitoring the clearance of the rod portion 23c measured by the gap
sensor 24. To be more specific, since the clearance becomes small when the rod portion
23c protrudes from the cylinder portion 22, and the clearance becomes large when the
rod portion 23c recedes in the cylinder portion 22, the monitoring of the hydraulic
actuator 20 can be achieved by monitoring the clearance.
[0044] The electromagnetic on-off valve 30 is housed in the concave portion 21a of the block
21. The electromagnetic on-off valve 30 is a two port type electromagnetic on-off
valve which includes an intake port 30a and an output port 30b. The intake port 30a
communicates with the second pipe line 21c of the block 21, and the output port 30b
communicates with the supply discharge pipe line 21d of the block 21. The electromagnetic
on-off valve 30 includes inside a spool 31 as well as a spring and a solenoid, not
shown in the figure. In the electromagnetic on-off valve 30, the spring pushes the
spool 31 to connect the intake port 30a and the output port 30b when a normal condition,
and the spool 31 cuts off the communication between the intake port 30a and the output
port 30b against a biasing force of the spring when the solenoid is excited. Thus,
the electromagnetic on-off valve 30 is capable of switching between a hydraulic oil
supply discharge condition and a hydraulic oil cut off condition.
[0045] Thus, when the hydraulic oil is provided to the supply discharge pipe line 21d formed
on the block 21 via the first pipe line 21b and the second pipe line 21c, both of
which are formed on the block 21, and the electromagnetic on-off valve 30, the hydraulic
oil is provided into the large diameter chamber 22b via the small diameter chamber
22a. Then, the hydraulic oil acts on the piston portion 23a of the piston 23, the
piston 23 is pushed out of the cylinder portion 22 (downward with respect to FIG.
1), and the rod portion 23c protrudes downward with respect to FIG. 1. Then, when
the solenoid of the electromagnetic on-off valve 30 is excited, the communication
between the intake port 30a and the output port 30b is cut off. In this condition,
if the rod portion 23c is pushed up to a side of the cylinder portion 22 (upward with
respect to FIG. 1), the piston 23 is plunged into the cylinder portion 22 until the
piston portion 23a of the piston 23 closes the longitudinal groove 23b1 communicated
with the flow pipe line 21e of the block 21, thereby, sealing hydraulic oil in the
small diameter chamber 22a and the large diameter chamber 22b. At this time, the piston
23 is stopped by hydraulic oil sealed by the small diameter chamber 22a and the large
diameter chamber 22b.
[0046] Afterward, when the solenoid of the electromagnetic on-off valve 30 is not excited,
the intake port 30a and the output port 30b returns to a condition in which the intake
port 30a and the output port 30b are in communication. In this condition, if the rod
portion 23c of the piston 23 is pushed up to the side of the cylinder portion 22 (upward
with respect to FIG. 1), the piston 23 moves upward and hydraulic oil flows out from
the supply discharge pipe line 21d of the block 21. The flowed hydraulic oil flows
out outside of the hydraulic actuator 20 via the output port 30b and intake port 30a
of the electromagnetic on-off valve 30, the second pipe line 21c, and the first pipe
line 21b. Then, the buffering portion 23b of the piston 23 is housed in the small
diameter chamber 22a of the cylinder portion 22, and a sequence of functions of the
hydraulic actuator 20 ends.
[0047] The electromagnetic on-off valve 30 is connected to the engine control unit 40. The
engine control unit 40 controls an exciting timing and an exciting time period of
the electromagnetic on-off valve 30, and is capable of controlling the electromagnetic
on-off valve 30 in units of milliseconds (1/1000 seconds) as desired.
[0048] An output port 50a of the accumulator 50 is connected to the first pipe line 21b
of the block 21. The accumulator 50 is an accumulating means for accumulating oil
pressure, and the accumulator 50 according to the embodiment is a mechanical accumulator.
[0049] As shown in FIG. 1, the accumulator 50 includes the output port 50a explained above,
an output pipe line 50b which extends from the output port 50a, an input pipe line
50c which crosses to the output pipe line 50b, and a input port 50d which communicates
with the input pipe line 50c. The input pipe line 50c communicates with a pressure
accumulating portion 52.
[0050] The pressure accumulating portion 52 includes a cylinder 55 formed on a body of the
accumulator 50. The cylinder 55 communicates with the input pipe line 50c, and is
configured such that hydraulic oil provided from the input port 50d and hydraulic
oil provided from the output port 50a can flow in. The cylinder 55 includes inside
a plunger 56 which slides in an axial direction of the cylinder 55 and a compression
spring 57 which pushes the plunger 56 toward a bottom wall of the cylinder 55 (toward
left in the figure).
[0051] Thus, although hydraulic oil is provided from the input port 50d of the accumulator
50 and hydraulic oil pushes plunger 56 toward the side (right side with respect to
FIG. 1), the plunger 56 can not resist a basing force of the compression spring 57,
and hydraulic oil flows out from the output port 50a. In contrast, when hydraulic
oil, which is flowed out from the hydraulic actuator 20 and posses a higher oil pressure
than an oil pressure of hydraulic oil provided from the input port 50d, is provided
from the output port 50a of the accumulator 50, the hydraulic oil pushes the plunger
56 toward the side (right side with respect to FIG. 1), and the plunger 56 moves toward
the side (toward left in the figure) against the biasing force of the compression
spring 57. At this time, hydraulic oil is accumulated (pressure accumulation) in the
pressure accumulating portion 52.
[0052] The hydraulic actuator 20, the electromagnetic on-off valve 30, and the accumulator
50 make up a hydraulic circuit 60, as shown in FIG. 3. A lubrication unit 61 which
is attached to the engine and provides lubricating oil to the engine is capable of
providing low pressure hydraulic oil to the hydraulic circuit 60. A check valve 62
is arranged between the lubrication unit 61 attached to the engine and the hydraulic
circuit 60. The check valve 62 allows providing hydraulic oil to the hydraulic circuit
60 from the lubrication unit 61 attached to the engine only if an oil pressure of
the hydraulic circuit 60 is lower than that of the lubrication unit 61 attached to
the engine, and does not allow hydraulic oil to flow from the hydraulic circuit 60
side to the lubrication unit 61 attached to the engine.
[0053] Also, a relief valve 63 is provided between the check valve 62 and the hydraulic
circuit 60 explained above. The relief valve 63 is capable of discharging hydraulic
oil of the hydraulic circuit 60 to an oil pan 64 of the engine when the oil pressure
of the hydraulic circuit 60 becomes higher than a predetermined pressure.
[0054] As explained above, the engine control unit 40 connected to the gap sensor 24 and
the electromagnetic on-off valve 30 is configured to detect which cylinder has the
engine piston EP come to a top dead center, based on a cylinder determination signal
(G signal) entered from TDC (Top Dead Center) sensor (cylinder determination signal
output means), as shown in FIG. 6. Also, the engine control unit 40 calculates a revolution
based on a revolution detection signal (Ne signal) entered from a crank angle sensor
(revolution detection signal output means), not shown in the figure. The engine control
unit 40 is configured to start to count number of pulses of the revolution detection
signal (square wave) when the engine piston EP of a cylinder to delay a closing timing
(for example, cylinder 5 in FIG. 6) comes to the upper dead center. Then, when the
counted number of pulses of the revolution detection signal reaches to a preset VVA
activation setup pulse, the engine control unit 40 turns on a VVA activation signal
and excites the electromagnetic on-off valve 30 for a preset VVA holding time Tw.
[0055] According to the engine valve device 1 equipped with the hydraulic circuit 60 mentioned
above, the lubrication unit 61 attached to the engine provides hydraulic oil to the
hydraulic circuit 60 by starting the engine. To be more specific, hydraulic oil is
provided to in order of the accumulator 50, the electromagnetic on-off valve 30, and
the hydraulic actuator 20 via the check valve 62. Thus, hydraulic oil is filled in
the electromagnetic on-off valve 30 and the hydraulic actuator 20.
[0056] Then, when the engine is started, power is transmitted to in order of the cam 18,
the tappet arm 14, the push rod 13, the rocker arm 9, and the crosshead 5 by engaging
with the crankshaft of the engine. The intake valve 3 opens and closes the intake
port 2 during the intake stroke of the engine, and the intake valve 3 closes the intake
port 2 during the compression stroke, the combustion stroke, and the exhaust stroke
of the engine.
[0057] During the compression stroke, the combustion stroke, and the exhaust stroke of the
engine, as shown in FIG. 2A, the intake valve 3 closes the intake port 2 by the biasing
force of the valve spring 4. At this time, a relation between a rotational angle of
the cam 14 and the valve lift amount has a relation shown by a close area in FIG.
4. More specifically, it has a relation in which the valve lift amount is 0 regardless
of the rotational angle of the cam 18.
[0058] When the intake stroke of the engine is started, power is transmitted to in order
of the tappet arm 14, the push rod 13, the rocker arm 9, and the crosshead 5 from
the cam 18, and the intake valve 3 lifts to gradually open the intake port 2. At this
time, a relation between the cam rotational angle and the valve lift amount has a
relation shown by an open function area in FIG. 4. More specifically, it has a relation
in which the valve lift amount gradually increases as the rotational angle of the
cam 18 increases.
[0059] At this time, the rod portion 23c of the piston 23 gradually protrudes (downward
with respect to FIG. 1), contacting with the crosshead 5, by gradually providing hydraulic
oil accumulated in the accumulator 50 to the small diameter chamber 22a and the large
diameter chamber 22b of the cylinder portion 22. To be more specific, hydraulic oil
is provided to in order of the electromagnetic on-off valve 30 and the hydraulic actuator
20. Here, if hydraulic oil is not accumulated in the accumulator 50, hydraulic oil
is gradually provided to the hydraulic circuit 60 from the lubrication unit 61 attached
to the engine via the check valve 62.
[0060] Then, when the valve lift amount becomes a maximum, as shown in FIG. 2B, the intake
port 2 becomes a full open state.
[0061] Afterward, as shown in FIG. 2C, by the biasing forces of the valve spring 4 and the
return spring 15, the crosshead 5, the rocker arm 9, the push rod 13, and the tappet
arm 14 follow the cam 18, and the intake valve 3 gradually closes the intake port
2. At this time, a relation between the cam rotational angle and the valve lift amount
has a relation shown by a close function area in FIG. 4. More specifically, it has
a relation in which the valve lift amount gradually decreases as the rotational angle
of the cam 18 increases.
[0062] At this time, the piston 23 is gradually housed in the cylinder portion 22, and hydraulic
oil of the small diameter chamber 22a and the large diameter chamber 22b of the cylinder
portion 22 is accumulated in the accumulator 50. Thus, the hydraulic actuator 20 has
a function of a piston pump. To be more specific, hydraulic oil is accumulated in
the accumulator 50 via the electromagnetic on-off valve 30 and the hydraulic actuator
20.
[0063] Then, as shown in fig. 4, when the valve lift amount becomes a minimum which is 0,
the intake valve 3 becomes a full close state as shown in FIG. 2E.
[0064] In contrast, in the close function area shown in FIG. 4, when the electromagnetic
on-off valve 30 is excited, the spool 31 cuts off the communication between the intake
port 30a and the output port 30b against the biasing force of the spring. More specifically,
the electromagnetic on-off valve 30 makes a transition from the hydraulic oil supply
discharge state to the hydraulic oil cut off state. Then, the piston 23 is pushed
into the cylinder portion 22 until the piston portion 23a of the piston 23 closes
the oil groove 22b1 communicated with the flow pipe line 21e of the block 21, and,
afterward, hydraulic oil is sealed in the small diameter chamber 22a and the large
diameter chamber 22b of the cylinder portion 22. Thus, the piston 23 is stopped by
hydraulic oil sealed in the small diameter chamber 22a and the large diameter chamber
22b.
[0065] Then, the rod portion 23c of the piston 23 pushes the crosshead 5, and the intake
valve 3 keeps to open at a predetermined gate opening, as shown in FIG. 2D. More specifically,
the closing timing of the intake port 2 by the intake valve 3 during the intake stroke
is delayed. Because of a mechanism in which the oil groove 22b1 is provided inside
the cylinder portion 22 and the piston portion 23a closes the oil groove 22b1, the
open state is maintained at the same gate opening. At this time, a relation between
the cam rotational angle and the valve lift amount has a relation shown by a close
delay area in FIG. 4. More specifically, it has a relation in which the valve lift
amount is constant although the rotational angle of the cam 18 increases.
[0066] As described above, although the rod portion 23c of the piston 23 pushes the crosshead
5 and the intake valve 3 keeps to open at the predetermined gate opening, the rocker
arm 9 tightly contacts with the push rod 13 by the biasing force of the return spring
15, and controlled by the surface configuration (cam profile) of the cam 18. Thus,
the clearance is generated between the crosshead 5 and the rocker arm 9 without dropping
the push rod 13 from the rocker arm 9.
[0067] When the electromagnetic on-off valve 30 is demagnetized after a predetermined time
period, the intake port 30a becomes in communication with the output port 30b again.
Thus, the intake valve 3 gradually closes the intake port 2 by the biasing force of
the valve spring 4.
[0068] At this time, the crosshead 5 pushes the piston 23, the piston 23 is housed inside
the cylinder portion 22 again, and hydraulic oil of the small diameter chamber 22a
and the large diameter chamber 22b of the cylinder portion 22 is accumulated in the
accumulator 50.
[0069] Then, as shown in FIG. 4, when the valve lift amount becomes the minimum which is
0, the intake valve 3 becomes a full close state as shown in FIG. 2E.
[0070] As described above, to delay the closing timing of the intake port 2 by the intake
valve 3 during the intake stroke, the engine control unit 40starts to count the number
of pulses of the revolution detection signal (Step S2), when the engine piston EP
of the cylinder to delay a closing timing (for example, cylinder 5 in FIG. 6) comes
to the upper dead center (Step S1: Yes), as shown in FIG. 5 and FIG. 6. Then, when
the counted number of pulses of the revolution detection signal reaches to the preset
VVA activation setup pulse (Step S3: Yes), the engine control unit 40 turns on the
VVA activation signal (Step S4). As described above, when the VVA activation signal
is turned on, the electromagnetic on-off valve 30 is excited for the preset VVA holding
time Tw (Step S5). Afterward, these routines are repeated to control the closing timing
of the intake port 2 to be delayed by the intake valve 3.
[0071] According to the engine valve device 1 of the embodiment described above, when the
electromagnetic on-off valve 30 is closed, the intake valve 3 engages with the rocker
arm 9 until the piston 23 of the hydraulic actuator 20 closes the oil groove 22b1
(flow pipe line 21e). After closing the oil groove 22b1 which is communicated with
the flow pipe line 21e, the open state of the intake valve 3 is maintained until the
electromagnetic on-off valve 30 is opened. Thus, the open state of the intake port
2 is maintained at the preset amount of opening regardless of the closing timing of
the electromagnetic on-off valve 30.
INDUSTRIAL APPLICABILITY
[0072] As explained above, an engine valve device of the present invention is applicable
to an engine valve device which varies an action of an engine valve, especially, is
adapted to an engine valve of a diesel engine.
1. An engine valve device including a cam which rotates by engaging with a crankshaft,
a rocker arm which follows a movement of the cam, and an intake valve which opens
and closes an intake port by interacting the rocker arm and a spring, the engine valve
device comprising:
a piston which is movable in a same direction as that of the intake valve;
a cylinder which houses the piston such that the piston is movable inside the cylinder;
a hydraulic actuator including the piston and the cylinder;
a hydraulic pipe line which communicates with a pressure chamber formed by the piston
and the cylinder;
an accumulation unit which accumulates hydraulic oil flowed out from the pressure
chamber via the hydraulic pipe line; and
an electromagnetic on-off valve which controls a flow of the hydraulic oil between
the pressure chamber and the accumulation unit, wherein
the hydraulic actuator, the hydraulic pipe line, the accumulation unit, and the electromagnetic
on-off valve make up a hydraulic circuit, and
the electromagnetic on-off valve is arranged on the hydraulic pipe line between the
hydraulic actuator and the accumulation unit.
2. An engine valve device including a cam which rotates by engaging with a crankshaft,
a rocker arm which follows a movement of the cam, and an intake valve which opens
or closes an intake port by interacting the rocker arm and a spring, the engine valve
device comprising a hydraulic circuit, wherein
the hydraulic circuit includes:
a hydraulic actuator which is activated by an open and close motion of the intake
valve, the hydraulic actuator stopping a close motion of the intake valve in an open
state when hydraulic oil is sealed in a pressure chamber;
an accumulation unit which accumulates the hydraulic oil flowed out from the pressure
chamber of the hydraulic actuator when the intake valve moves to close, and which
provides the hydraulic oil to the pressure chamber of the hydraulic actuator when
the intake valve moves to open; and
an electromagnetic on-off valve which controls a flow of the hydraulic oil from the
hydraulic actuator to the accumulation unit, wherein
the electromagnetic on-off valve is arranged between the hydraulic actuator and the
accumulation unit.
3. The engine valve device according to claim 1 or 2, further comprising a hydraulic
oil supply unit which provides the hydraulic oil to the hydraulic circuit.
4. The engine valve device according to claim 3, wherein the hydraulic oil supply unit
is a lubrication unit which provides lubricating oil to an engine and is attached
to the engine.
5. The engine valve device according to any of claims 1 to 4, further comprising an auxiliary
pipe line which allows the flow of the hydraulic oil from the pressure chamber of
the hydraulic actuator to the accumulation unit, wherein
the auxiliary pipe line includes a port which opens when the piston of the hydraulic
actuator comes to a predetermined section, the piston of the hydraulic actuator follows
the intake valve moving to a closing direction.
6. The engine valve device according to any of claims 3 to 5, further comprising a check
valve which supplies the hydraulic oil from the hydraulic oil supply unit to the hydraulic
circuit only if an oil pressure of the hydraulic circuit is lower than that of the
hydraulic oil supply unit, and the check valve is arranged between the hydraulic oil
supply unit and the hydraulic circuit.
7. The engine valve device according to any of claims 1 to 6, wherein the pressure chamber
of the hydraulic actuator is configured to cushion a shock when the intake valve closes.
8. The engine valve device according to any of claims 2 to 7, further comprising:
a push rod which transmits motion from the cam to the rocker arm, the push rod being
disposed between the cam and the rocker arm; and
a biasing unit which biases the rocker arm to tightly contact with the push rod.