BACKGROUND OF THE INVENTION
1. Field of the Invention
[0001] The present invention relates to a valve train for an internal combustion engine.
2. Description of the Related Art
[0002] Conventionally, an internal combustion engine has a valve train for intake and exhaust
in a combustion chamber. Such a valve train mainly includes a valve, a spring retainer,
a pair of cotters, a valve spring, and a valve lifter.
[0003] The valve includes a stem movably supported by a cylinder head, and a valve head
provided at an end of the stem. The spring retainer is mounted at another end of the
stem via the pair of cotters. A valve spring seat is fixed to the cylinder head. The
valve spring is arranged between the spring retainer and the valve spring seat. The
valve lifter is provided at an end portion of the valve spring so as to cover the
end portion of the valve spring and the spring retainer (for example, see Japanese
Unexamined Patent Application Publication No.
2004-27978).
[0004] With the conventional valve train, an inner diameter of the valve lifter is larger
than an outer diameter of the valve spring, and hence, a clearance is formed between
the valve lifter and the valve spring in a radial direction. Accordingly, the valve
lifter can be placed at a predetermined position, for example, even when the end portion
of the valve spring is deviated from the spring retainer in the radial direction during
assembly. In this case, since the end portion of the valve spring and the spring retainer
are covered with the valve lifter, it is difficult to recognize whether the end portion
of the valve spring is deviated from the spring retainer or not, from the outside.
Thus, a product with the valve spring defectively assembled may be shipped.
SUMMARY OF THE INVENTION
[0005] Accordingly, it is an object of the present invention to provide a valve train for
an internal combustion engine capable of preventing defective assembly of parts.
[0006] A valve train for an internal combustion engine according to an aspect of the present
invention includes a valve, a supporting member, a valve spring, and a valve lifter.
The valve includes a stem supported by a cylinder head movably in an axial direction,
and a valve head provided at a first end portion of the stem. The supporting member
is mounted at a second end portion of the stem. The valve spring is arranged between
the cylinder head and the supporting member. The valve lifter provided to be in contact
with the second end portion of the stem. The supporting member includes a supporting
portion that supports an end portion of the valve spring. The supporting portion includes
a circular contact surface that comes into contact with the end portion of the valve
spring in the axial direction, and a restriction surface arranged at the inside of
the contact surface in a radial direction along a direction orthogonal to the axial
direction, the restriction surface being capable of coming into contact with the end
portion of the valve spring. At least one of the supporting member and the valve lifter
includes a guide portion that guides the end portion of the valve spring to the supporting
portion.
[0007] With the valve train, since the end portion of the valve spring is guided to the
supporting portion by the guide portion, the end portion of the valve spring can be
guided to a predetermined position even when the position of the valve spring is deviated
from the supporting member during assembly. Accordingly, the defective assembly of
parts can be prevented.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008]
Fig. 1 is a partial cross section showing a valve train according to a first embodiment
of the present invention;
Fig. 2 is a partial cross section showing a spring retainer and its periphery according
to the first embodiment;
Fig. 3A is a plan view showing the spring retainer according to the first embodiment;
Fig. 3B is a cross section showing the spring retainer according to the first embodiment;
Fig. 4A is an example phase diagram showing the spring retainer during assembly according
to the first embodiment;
Fig. 4B is an example phase diagram showing the spring retainer during assembly according
to the first embodiment;
Fig. 5 is an example phase diagram showing the spring retainer during assembly according
to the first embodiment;
Fig. 6 is a partial cross section showing a valve train according to a second embodiment
of the present invention;
Fig. 7 is a partial cross section showing a valve lifter and its periphery according
to the second embodiment;
Fig. 8A is an example phase diagram showing the valve lifter during assembly according
to the second embodiment;
Fig. 8B is an example phase diagram showing the valve lifter during assembly according
to the second embodiment;
Fig. 9 is an example phase diagram showing the valve lifter during assembly according
to the second embodiment;
Fig. 10A is a plan view showing a spring retainer according to a modification;
Fig. 10B is a cross section showing the spring retainer according to the modification;
Fig. 11A is a plan view showing a spring retainer according to another modification;
Fig. 11B is a cross section showing the spring retainer according to the modification;
Fig. 12A is a cross section showing a spring retainer according to still another modification;
and
Fig. 12B is a cross section showing the spring retainer according to yet another modification.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0009] Hereinafter, embodiments of the present invention are described below with reference
to the attached drawings.
First Embodiment
General Configuration of Valve Train
[0010] A valve train 1 according to a first embodiment of the present invention is described
with reference to Fig. 1. Fig. 1 is a partial cross section of the valve train 1.
[0011] Referring to Fig. 1, the valve train 1 mainly includes a valve 2, a spring retainer
3, a pair of cotters 4, a valve spring 5, and a valve lifter 6.
[0012] The valve 2 includes a stem 22 and a valve head 21. The stem 22 is movably supported
by a cylinder head 9. The stem 22 is a rod-like portion having a central axis A, and
includes a rod-like stem body 25, and a head portion 23 provided at an end portion
of the stem body 25. The stem body 25 is supported by a cylindrical valve guide 91
fixed to the cylinder head 9, in a movable manner in a direction along the central
axis A (hereinafter, referred to as an axial direction). The valve head 21 is provided
at an end portion of the stem 22 at a B1 side in the axial direction (first end portion).
The valve head 21 can come into contact with a valve seat 92 fixed to the cylinder
head 9 in the axial direction. A valve spring seat 7 and an oil seal 8 are provided
at an outer peripheral side of the stem 22.
[0013] The valve spring 5 is, for example, a coil spring, which is arranged at the outer
peripheral side of the stem 22 so as to be compressed in the axial direction. In particular,
an end portion of the valve spring 5 at the B1 side in the axial direction is supported
by the valve spring seat 7. An end portion of the valve spring 5 at a B2 side in the
axial direction is supported by the spring retainer 3 mounted at an end portion of
the stem 22 at the B2 side in the axial direction (second end portion). The valve
spring seat 7 and the spring retainer 3 restrict the movement of the valve spring
5 in a direction orthogonal to the central axis A (hereinafter, referred to as a radial
direction). A central axis of the valve spring 5 is substantially aligned with the
central axis A of the stem 22. The valve spring 5, which is initially in a compressed
state, is arranged between the cylinder head 9 and the spring retainer 3. A spring
force of the valve spring 5 causes the valve head 21 to be pressed to the valve seat
92 fixed to the cylinder head 9.
[0014] The valve lifter 6 is a member on which a cam fixed to a camshaft (not shown) slides.
The valve lifter 6 covers an end portion of the valve spring 5 and the spring retainer
3. In particular, the valve lifter 6 includes a cylindrical portion 61 arranged at
the outer peripheral side of the spring retainer 3, and a disk-like cap portion 62
provided at an end portion of the cylindrical portion 61 at the B2 side in the axial
direction.
[0015] The valve lifter 6 is supported by the cylinder head 9 movably in the axial direction,
and also supported by the valve 2 in the axial direction. In particular, the cylindrical
portion 61 is inserted to a tappet hole 93 of the cylinder head 9. The cap portion
62 is in contact with the head portion 23 of the stem 22 in the axial direction. A
clearance is provided between the cylindrical portion 61 and an end of the valve spring
5 in the radial direction.
Configurations of Spring Retainer and Peripheral Members thereof
[0016] The valve train 1 features a configuration of the spring retainer 3. Referring to
Figs. 2, 3A, and 3B, the configurations of the spring retainer 3 and peripheral members
thereof are described. Fig. 2 is a partial cross section showing the spring retainer
3 and its periphery. Figs. 3A and 3B are a plan view and a cross section of the spring
retainer 3.
[0017] Referring to Fig. 2, the spring retainer 3 is a member to support the end portion
of the valve spring 5 with respect to the valve 2. The spring retainer 3 is mounted
at the end portion of the stem 22 at the B2 side in the axial direction via the pair
of cotters 4.
[0018] The pair of cotters 4 include two semi-cylinder members, which are mounted at the
B1 side in the axial direction of the head portion 23 so as to sandwich the stem body
25. The cotters 4 include protrusions 41 protruding inward in the radial direction.
The protrusions 41 are fitted into grooves 24 formed at the stem body 25 at the B2
side in the axial direction. Hence, the positions of the cotters 4 in the axial direction
are determined with respect to the stem 22.
[0019] The spring retainer 3 is fitted onto outer peripheral portions of the pair of cotters
4. In particular, referring to Figs. 2, 3A, and 3B, the spring retainer 3 includes
a cylindrical boss 31, a circular supporting portion 35 extending outward in the radial
direction from the boss 31, and three ribs 34 (first ribs) functioning as a first
guide portion.
[0020] Referring to Figs. 2, 3A, and 3B, the boss 31 includes a tapered hole 31a. The pair
of cotters 4 are fitted into the hole 31a. The outer peripheral portions of the cotters
4 are tapered like the hole 31a. Hence, the movement of the spring retainer 3 to the
B2 side in the axial direction relative to the cotters 4 is restricted. With the configurations,
the position and angle of the spring retainer 3 in the axial direction can be determined
with respect to the valve 2.
[0021] The supporting portion 35 includes a contact portion 32 that supports an end turn
51 (end portion) of the valve spring 5 in the axial direction, and a restriction portion
33 that supports the end turn 51 in the radial direction. The contact portion 32 is
a circular portion for supporting the end turn 51 of the valve spring 5, and has a
circular contact surface 32a that comes into contact with the end turn 51 in the axial
direction. For example, the contact surface 32a is arranged in parallel to a plane
orthogonal to the central axis A.
[0022] The restriction portion 33 is formed at the B1 side in the axial direction of the
contact portion 32. The restriction portion 33 includes a restriction surface 33a
capable of coming into contact with the end turn 51 in the radial direction, and a
circular surface 33b directed to the B1 side in the axial direction. The restriction
surface 33a is a peripheral surface perpendicular to the radial direction, and is
arranged at the inside of the contact surface 32a in the radial direction. The restriction
portion 33 restricts the movement in the radial direction of the end turn 51 of the
valve spring 5 relative to the spring retainer 3. The contact surface 32a and the
restriction surface 33a define a housing space S at the outer peripheral portion of
the spring retainer 3. The housing space S houses the end turn 51.
[0023] The ribs 34 are plate portions extending outward from the boss 31 in the radial direction.
For example, the ribs 34 are integrally formed with the boss 31 and the supporting
portion 35. Referring to Fig. 3A, the three ribs 34 are arranged at even pitches around
the central axis A. The ribs 34 are arranged at the B1 side in the axial direction
of the restriction portion 33 so as to couple the boss 31 and the supporting portion
35. The ribs 34 are formed on the circular surface 33b.
[0024] Each of the ribs 34 has a guide surface 34a functioning as a first guide surface
inclined toward the radial direction with respect to the central axis A. The guide
surface 34a is a plane directed to the B1 side in the axial direction and to the outside
in the radial direction. The guide surface 34a is formed such that the position thereof
in the radial direction approaches the contact surface 32a and the restriction surface
33a, toward the B2 side in the axial direction. That is, the guide surface 34a is
formed such that the position in the axial direction approaches the contact surface
32a and the restriction surface 33a, toward the outside in the radial direction (as
being away from the central axis A).
[0025] In the view in the axial direction, the rib 34 extends from the boss 31 toward an
inner peripheral edge of the contact surface 32a, toward the outside in the radial
direction. In particular, the rib 34 extends from an end surface 31b of the boss 31
toward the contact surface 32a and the restriction surface 33a, toward the outside
in the radial direction. An edge of the guide surface 34a at the inside in the radial
direction substantially corresponds to an outer peripheral edge of the end surface
31b. An edge of the guide surface 34a at the outside in the radial direction substantially
corresponds to an edge of the restriction surface 33a at the B1 side in the axial
direction. Hence, the end surface 31b, the guide surface 34a, and the restriction
surface 33a are continuously formed (connected with each other).
Assembly Procedure
[0026] In the valve train 1, since the spring retainer 3 includes the ribs 34, defective
assembly of parts can be prevented. Here, an assembly procedure of the valve train
1 is described with reference to Figs. 1 through 5. Figs. 4A, 4B, and 5 show example
phase diagrams of the spring retainer 3 during assembly.
[0027] Referring to Fig. 1, first, the stem 22 is inserted to the valve guide 91 of the
cylinder head 9. The valve 2 is supported by a jig (not shown) from a combustion engine
side so as to prevent the stem 22 from falling to the combustion engine side (in Fig.
1, B1 side in the axial direction). Then, the oil seal 8 and the valve spring seat
7 are fitted onto the stem 22, and the valve spring 5 is arranged on the valve spring
seat 7.
[0028] Then, the spring retainer 3 is temporarily placed at the end portion of the valve
spring 5. The pair of cotters 4 are inserted into the hole 31a of the spring retainer
3. The spring retainer 3 and the cotters 4 are pushed down to the B1 side in the axial
direction with respect to the stem 22 until the protrusions 41 of the cotters 4 are
fitted into the grooves 24 of the stem 22. After the protrusions 41 of the cotters
4 are fitted into the grooves 24, a pressing force to the spring retainer 3 is released.
As a result, the spring retainer 3 is pushed up to the B2 side in the axial direction
by a spring force of the valve spring 5, and hence, the tapered cotters 4 are fitted
into the tapered hole 31a. As described above, the spring retainer 3 is positioned
with respect to the valve 2 by the tapered cotters 4 and the spring force of the valve
spring 5.
[0029] Further, the valve lifter 6 is fitted into the tappet hole 93. The valve lifter 6
is mounted at the spring retainer 3 and the end turn 51 of the valve spring 5. Then,
the camshaft (not shown) is assembled with the cylinder head 9. Thus, the assembly
of the valve train 1 is completed.
[0030] Herein, a case is assumed in which the spring retainer 3 is temporarily placed at
the end turn 51 of the valve spring 5 with a deviation (Fig. 4A). In this case, the
end turn 51 of the valve spring 5 is not fitted to the restriction portion 33, but
comes into contact with the rib 34.
[0031] After the spring retainer 3 is temporarily placed, since the spring retainer 3 is
pushed down with respect to the stem 22, a pressing force F1 to the B1 side in the
axial direction acts on the spring retainer 3, and a force F2 to the outside in the
radial direction acts on the end turn 51 via the guide surface 34a (Fig. 4A). As a
result, the valve spring 5 is moved in the radial direction along the guide surface
34a of the rib 34 relative to the spring retainer 3 (or the spring retainer 3 is moved
in the radial direction relative to the valve spring 5), and the end turn 51 is guided
to the housing space S of the spring retainer 3. Accordingly, the end turn 51 is fitted
to the restriction portion 33 (Fig. 4B). After the cotters 4 are mounted at the stem
22, when the pressing force F1 to the spring retainer 3 is released, the spring retainer
3 is positioned at a predetermined position with respect to the valve 2 by the cotters
4 and the spring force of the valve spring 5 (Fig. 5). Accordingly, the valve spring
5 is also arranged at the predetermined position with respect to the valve 2 and the
spring retainer 3.
[0032] As described above, with the valve train 1, the valve spring 5 is guided to the predetermined
position by the rib 34 with respect to the spring retainer 3. Accordingly, the defective
assembly of parts such as the valve spring 5 and the spring retainer 3 can be prevented.
Features
[0033] Features of the valve train 1 are described below.
- (1) As described above, with the valve train 1, the end turn 51 of the valve spring
5 is guided to the supporting portion 35 by the rib 34 (in particular, to the housing
space S defined by the restriction portion 33 and the contact surface 32a) even when
the end turn 51 is deviated from the spring retainer 3 during assembly. As a result,
after the assembly is completed, the end turn 51 and the spring retainer 3 are arranged
at the predetermined positions without a deviation.
Accordingly, with the valve train 1, the defective assembly of parts such as the valve
spring 5 and the spring retainer 3 can be prevented.
- (2) In the view in the axial direction, each rib 34 having the guide surface 34a extends
from the boss 31 to the inner peripheral edge of the contact surface 32a, toward the
outside in the radial direction. In particular, in the view in the axial direction,
the rib 34 extends from the inner peripheral edge of the contact surface 32a, toward
the inside in the radial direction. The edges of the three guide surfaces 34a at the
outside in the radial direction substantially correspond to the edge of the restriction
surface 33a.
As described above, since no additional plane or the like is provided between the
guide surface 34a and the restriction surface 33a, and the guide surface 34a and the
restriction surface 33a are continuously formed, the end turn 51 is reliably guided
to the supporting portion 35 by the guide surface 34a.
- (3) Each rib 34 has the guide surface 34a inclined toward the radial direction with
respect to the central axis A of the stem 22. In particular, the guide surface 34a
is formed such that the position thereof in the radial direction approaches the contact
surface 32a, toward the B2 side in the axial direction. Accordingly, the pressing
force F1 in the axial direction acting between the spring retainer 3 and the valve
spring 5 is converted into the force F2 to the outside in the radial direction by
the rib 34. Accordingly, the end turn 51 of the valve spring 5 can be guided to the
predetermined position by the pressing force in the axial direction during assembly.
- (4) The portion (guide portion) for guiding the end turn 51 of the valve spring 5
is defined by the plate-like ribs 34. Accordingly, an increase in weight of the spring
retainer 3 can be minimized. Also, the ribs 34 can efficiently increase the strength
of the spring retainer 3.
[0034] Further, since the three ribs 34 are arranged at the even pitches around the central
axis A, defective assembly of parts can be prevented while the number of ribs 34 is
minimized, that is, the increase in weight of the spring retainer 3 is minimized.
Second Embodiment
[0035] In the above-described first embodiment, the portion for guiding the end turn 51
of the valve spring 5 is provided at the spring retainer 3. However, the member having
the guide portion is not limited to the spring retainer 3. Here, a valve train 101
according to a second embodiment is described with reference to Figs. 6 and 7. Fig.
6 is a partial cross section showing the valve train 101. Fig. 7 is a partial cross
section showing a valve lifter 106 and its periphery.
[0036] Components having substantially similar functions to those of the first embodiment
refer reference numerals similar to those of the first embodiment, and detailed description
thereof is omitted.
Configuration of Valve Train
[0037] In the valve train 101, a guide portion is provided at the valve lifter 6. In particular,
referring to Fig. 6, a spring retainer 103 does not have a rib 34 unlike the above-described
spring retainer 3. Accordingly, the spring retainer 103 does not have a function of
guiding the end turn 51 of the valve spring 5 to the supporting portion 35.
[0038] Referring to Fig. 7, the valve lifter 106 includes a cylindrical portion 161, a cap
portion 162 formed at the B2 side in the axial direction of the cylindrical portion
161, and three ribs 163 (second ribs) serving as a second guide portion.
[0039] The ribs 163 are plate-like portions extending from an inner peripheral edge of the
cylindrical portion 161 to the inside in the radial direction. For example, the ribs
163 are integrally formed with the cylindrical portion 161 and the cap portion 162.
The three ribs 163 are arranged at even pitches around the central axis A, with a
clearance arranged at the outside of the supporting portion 35 in the radial direction.
[0040] Each of the ribs 163 includes a guide surface 163a functioning as a second guide
surface inclined toward the radial direction with respect to the central axis A. The
guide surface 163a is a plane directed to the B1 side in the axial direction and to
the inside in the radial direction. The guide surface 163a is formed such that a position
thereof in the radial direction approaches the contact surface 32a, toward the B2
side in the axial direction. That is, the guide surface 163a is formed such that the
position thereof in the axial direction approaches the contact surface 32a and the
restriction surface 33a, toward the inside in the radial direction (approach to the
central axis A). An edge of the guide surface 163a at the inside in the radial direction
is arranged at the position corresponding to the position of the contact surface 32a
in the axial direction while the cap portion 162 is in contact with the head portion
23.
Assembly Procedure
[0041] For example, a case is assumed in which the spring retainer 103 is fixed to the valve
2, and the end turn 51 of the valve spring 5 is deviated from the spring retainer
103 (Fig. 8A). In this case, since a part of the end turn 51 protrudes from the contact
portion 32 outward in the radial direction, when the valve lifter 106 is mounted at
the valve spring 5, the guide surface 163a of the rib 163 comes into contact with
the end turn 51 of the valve spring 5 (Fig. 8B). In this state, the cap portion 162
of the valve lifter 106 is not in contact with the head portion 23.
[0042] For example, when the valve lifter 106 is pressed by an operator or an assembly apparatus,
a pressing force F11 to the B1 side in the axial direction acts on the valve lifter
106. As a result, a force F12 acts to the inside in the radial direction via the guide
surface 163a. Accordingly, referring to Fig. 9, the end turn 51 of the valve spring
5 is fitted to the restriction portion 33, and the valve lifter 106 is placed at a
predetermined position.
[0043] The pressing force F11 may be a pressing force applied by the operator or the assembly
apparatus, or, for example, a pressing force transmitted from the cam to the valve
lifter 106 when the camshaft is rotated.
[0044] Also, as shown in Fig. 8B, when the rib 163 of the valve lifter 106 comes into contact
with the end turn 51, the position of the valve lifter 106 is at the B2 side in the
axial direction with respect to the predetermined position of the valve lifter 106.
Accordingly, the position of the valve lifter 106 in the axial direction can be checked
after the assembly of the valve lifter 106. Thus, it is possible to recognize whether
the valve spring 5 is arranged at the predetermined position or not, from the outside.
Features
[0045] Features of the valve train 101 are described below.
- (1) With the valve train 101, the end turn 51 of the valve spring 5 is guided to the
supporting portion 35 by the rib 163 (in particular, to the housing space S defined
by the restriction portion 33 and the contact surface 32a) even when the end turn
51 is deviated from the spring retainer 3 during assembly. As a result, after the
assembly is completed, the end turn 51 and the spring retainer 103 are arranged at
the predetermined positions without a deviation. Accordingly, with the valve train
101, defective assembly of parts such as the valve spring 5 and the spring retainer
103 can be prevented.
In addition, since the position of the valve lifter 106 in the axial direction is
checked, it is possible to recognize whether the valve spring 5 is arranged at the
predetermined position or not, from the outside. For example, the positions of parts
can be readjusted accordingly.
As described above, with the valve train 101, the defective assembly of parts such
as the valve spring 5 and the spring retainer 103 can be prevented.
- (2) Each rib 163 has the guide surface 163a inclined toward the radial direction with
respect to the central axis A of the stem 22. In particular, the guide surface 163a
of the rib 163 is formed such that the position thereof in the radial direction approaches
the contact surface 32a to the B2 side in the axial direction. Accordingly, the pressing
force F11 acting between the valve lifter 106 and the valve spring 5 is converted
by the rib 163 into the force F12 to the inside in the radial direction. Thus, the
end turn 51 of the valve spring 5 can be guided to the predetermined position by the
pressing force in the axial direction during assembly.
- (3) The portion (guide portion) for guiding the end turn 51 of the valve spring 5
is defined by the plate-like ribs 163. Accordingly, an increase in weight of the valve
lifter 106 can be minimized. Also, the ribs 163 can efficiently increase the strength
of the valve lifter 106.
Further, since the three ribs 163 are arranged at the even pitches around the central
axis A, the defective assembly of parts can be prevented while the number of ribs
163 is minimized, that is, the increase in weight of the valve lifter 106 is minimized.
- (4) When the valve lifter 106 is arranged at the predetermined position (when the
cap portion 162 of the valve lifter 106 is in contact with the head portion 23 of
the stem 22), the edges of the guide surfaces 163a at the inside in the radial direction
are arranged at the positions corresponding to the position of the contact surface
32a in the axial direction. Accordingly, the end turn 51 of the valve spring 5 can
be reliably guided to the supporting portion 35 by the rib 163.
Modifications
[0046] The specific configuration of the present invention is not limited to the above-described
embodiments, and may include various modifications and changes within the scope of
the present invention.
- (A) The first embodiment may be combined with the second embodiment. In particular,
the valve train 1 according to the first embodiment may employ the valve lifter 106
according to the second embodiment, instead of the valve lifter 6.
- (B) In the first and second embodiments, while the guide portion is defined by the
three ribs 34 or 163, the number of ribs 34 or 163 is not limited to three.
Also, while the ribs 34 are the plate-like portions, a guide portion may be part of
an integrally formed structure. For example, referring to Figs. 10A and 10B, a spring
retainer 203 includes the boss 31, the supporting portion 35, and a guide portion
234. The guide portion 234 has a guide surface 234a inclined with respect to the central
axis A.
In this case, the weight of the spring retainer 203 is increased as compared with,
for example, the spring retainer 3, however, the end turn 51 of the valve spring 5
reliably comes into contact with the guide surface 234a even when the end turn 51
of the valve spring 5 is deviated from the spring retainer 203. Accordingly, the end
turn 51 of the valve spring 5 can be reliably guided to the supporting portion 35.
Alternatively, the valve lifter 106 may be changed from the plate-like guide portions
into a circular guide portion.
- (C) In the first embodiment, the restriction surface 33a of the spring retainer 3
is provided at the restriction portion 33. However, for example, restriction surfaces
33a may be provided at the ribs 34. In particular, a spring retainer 303 shown in
Figs. 11A and 11B includes the boss 31, the supporting portion 35, and three ribs
334. The ribs 334 include guide surfaces 334a and restriction surfaces 334b. The guide
surfaces 334a correspond to the above-mentioned guide surfaces 34a. The restriction
surfaces 334b correspond to the above-mentioned restriction surface 33a. The guide
surfaces 334a and the restriction surfaces 334b are connected with each other, and
are continuously formed.
In this case, since the restriction portion 33 for restricting the movement of the
end turn 51 in the radial direction is part of the ribs 334, reduction in weight can
be further promoted as compared with the above-described spring retainer 3.
- (D) In the first embodiment, the guide surface 34a of the spring retainer 3 is a plane.
However, the guide surface 34a is not limited to a plane, and may be, for example,
a curved plane or combination of a plane and a curved plane.
For example, in a spring retainer 403 shown in Fig. 12A, a rib 434 has a curved guide
surface 434a protruding outward in the radial direction. In this case, an inclination
of the guide surface 434a with respect to a plane orthogonal to the central axis A
is increased near the restriction surface 33a as compared with an inclination of the
rib 34. Hence, in particular, a guide function of the rib 434 near the restriction
surface 33a is increased.
Alternatively, in a spring retainer 503 shown in Fig. 12B, a rib 534 has a curved
guide surface 534a being depressed inward in the radial direction. In this case, the
weight of the spring retainer 503 can be reduced as compared with the case with the
above-mentioned rib 34.
- (E) In the first embodiment, the ribs 34 of the spring retainer 3 are arranged at
the even pitches around the central axis A. However, the ribs 34 may be arranged at
uneven pitches unless the guide function of the ribs 34 is degraded.
Also, similarly to the ribs 34, the ribs 163 may be arranged at positions deviated
from the even pitches unless the guide function of the ribs 163 is degraded.
- (F) In the first embodiment, the edge of the guide surface 34a at the outside in the
radial direction substantially corresponds to the edge of the restriction surface
33a at the B1 side in the axial direction. Herein, the phrase "substantially corresponding"
includes a situation in which the edge of the guide surface 34a at the outside in
the radial direction is deviated from the edge of the restriction surface 33a at the
B1 side in the axial direction unless the guide function of the ribs 34 is degraded.
- (G) In the second embodiment, the edge of the guide surface 163a of the rib 163 is
arranged at the position corresponding to the position of the contact surface 32a
in the axial direction while the cap portion 162 is in contact with the head portion
23. However, the guide surface 163a may be arranged at the B1 side of the contact
surface 32a in the axial direction. That is, the rib 163 may be elongated to the B1
side in the axial direction. In this case, although the weight of the valve lifter
106 is increased as compared with the case in the second embodiment, a function of
guiding the end turn 51 of the valve spring 5, or a function of recognizing a deviation
of the valve spring 5 from the outside can be enhanced.
[0047] With the valve train according to the present invention, the defective assembly of
parts can be prevented. Thus, the present invention is useful in the field of a valve
train for an internal combustion engine.
1. A valve train (1, 101) for an internal combustion engine, comprising:
a valve (2) which includes
a stem (22) supported by a cylinder head (9) movably in an axial direction, and
a valve head (21) provided at a first end portion of the stem (22);
a supporting member (3, 103) mounted at a second end portion of the stem (22);
a valve spring (5) arranged between the cylinder head (9) and the supporting member
(3, 103); and
a valve lifter (6, 106) provided to be in contact with the second end portion of the
stem (22),
wherein the supporting member (3, 103) includes
a supporting portion (35) that supports an end portion of the valve spring (5), the
supporting portion which includes
a circular contact surface (32a) that comes into contact with the end portion of the
valve spring (5) in the axial direction, and
a restriction surface (33a) arranged at the inside of the contact surface (32a) in
a radial direction along a direction orthogonal to the axial direction, the restriction
surface (33a) being capable of coming into contact with the end portion of the valve
spring (5), and
wherein at least one of the supporting member (3) and the valve lifter (6, 106) includes
a guide portion (34, 163) that guides the end portion of the valve spring (5) to the
supporting portion (3, 103).
2. The valve train (1, 101) for an internal combustion engine according to Claim 1, wherein
the guide portion (34, 163) has a guide surface (34a, 163a) inclined with respect
to a central axis (A) of the stem (22).
3. The valve train (1) for an internal combustion engine according to Claim 2, wherein
the supporting member (35) includes a first guide portion (34) functioning as the
guide portion (34, 163) arranged near the central axis (A) with respect to the restriction
surface (33a) and near the first end portion of the stem (22).
4. The valve train (1) for an internal combustion engine according to Claim 3, wherein
the first guide portion (34) has a first guide surface (34a) functioning as the guide
surface (34a, 163a) formed such that a position thereof in the direction orthogonal
to the axial direction approaches the contact surface (32a) toward the second end
portion in the axial direction.
5. The valve train (1) for an internal combustion engine according to Claim 4, wherein
an edge of the first guide surface (34a) located farthest from the central axis (A)
substantially corresponds to an edge of the restriction surface (33a).
6. The valve train (1) for an internal combustion engine according to any of Claims 3
to 5, wherein the first guide portion (34) is at least three plate-like first ribs
(34) extending in the axial direction.
7. The valve train (1) for an internal combustion engine according to Claim 6, wherein
the at least three first ribs (34) are arranged at substantially even pitches around
the central axis (A).
8. The valve train (101) for an internal combustion engine according to Claim 2, wherein
the valve lifter (6) includes a second guide portion (163) functioning as the guide
portion (34, 163) arranged at the outside of the supporting portion (35).
9. The valve train (101) for an internal combustion engine according to Claim 8, wherein
the second guide portion (163) has a second guide surface (163a) functioning as the
guide surface (34a, 163a) formed such that a position thereof in the direction orthogonal
to the axial direction approaches the contact surface (32a) toward the second end
portion in the axial direction.
10. The valve train (101) for an internal combustion engine according to Claim 8 or 9,
wherein the second guide portion (163) is at least three plate-like second ribs (163)
extending in the axial direction.
11. The valve train (101) for an internal combustion engine according to claim 10, wherein
the at least three second ribs (163) are arranged at substantially even pitches around
the central axis (A).
12. The valve train (101) for an internal combustion engine according to any of Claims
8 to 11, wherein an edge of the second guide surface (163a) located nearest to the
central axis (A) is arranged at a position corresponding to a position of the contact
surface (32a) or at a position near the first end portion of the stem (22) with respect
to the contact surface (32a).