U.S. patent application number 13/824718 was filed with the patent office on 2013-11-07 for cam follower apparatus.
This patent application is currently assigned to NSK Ltd.. The applicant listed for this patent is Satoshi Hachisuka, Hiroshi Noda. Invention is credited to Satoshi Hachisuka, Hiroshi Noda.
Application Number | 20130291817 13/824718 |
Document ID | / |
Family ID | 48798870 |
Filed Date | 2013-11-07 |
United States Patent
Application |
20130291817 |
Kind Code |
A1 |
Noda; Hiroshi ; et
al. |
November 7, 2013 |
CAM FOLLOWER APPARATUS
Abstract
Provided is a cam follower apparatus that has excellent
durability, assembly characteristics and freedom of design, and
together with being able to reduce the size and weight, is able to
reduce the manufacturing cost. Both end sections of a support shaft
3a are inserted into support holes 15b, 15c in support wall
sections 12b, 12c, and the support shaft 3a is supported by the
support wall sections 12b, 12c such that relative rotation is
possible. An inner ring 16, having an outer diameter D.sub.16 that
is greater then the inner diameter d.sub.15 of the support holes
15b, 15c, is fitted around the outer circumferential surface of the
middle section in the axial direction of the support shaft 9a so as
to be able to rotate together with the support shaft 9a. Moreover,
a plurality of cylindrical rollers 13 are arranged between an
inner-ring raceway 17, which is formed around the outer
circumferential surface of the inner ring 16, and an outer-ring
raceway 18, which is formed around the inner circumferential
surface of a tappet roller 8b that is provided on the
outer-diameter side of the inner ring, so as to be able to roll
freely.
Inventors: |
Noda; Hiroshi; (Gunma,
JP) ; Hachisuka; Satoshi; (Gunma, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Noda; Hiroshi
Hachisuka; Satoshi |
Gunma
Gunma |
|
JP
JP |
|
|
Assignee: |
NSK Ltd.
Tokyo
JP
|
Family ID: |
48798870 |
Appl. No.: |
13/824718 |
Filed: |
August 28, 2012 |
PCT Filed: |
August 28, 2012 |
PCT NO: |
PCT/JP12/71726 |
371 Date: |
May 9, 2013 |
Current U.S.
Class: |
123/90.39 |
Current CPC
Class: |
F01L 2305/02 20200501;
F01L 1/181 20130101 |
Class at
Publication: |
123/90.39 |
International
Class: |
F01L 1/18 20060101
F01L001/18 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 19, 2012 |
JP |
2012-008575 |
Feb 28, 2012 |
JP |
2012-040874 |
Claims
1. A cam follower apparatus, comprising: a rocker arm that has a
pair of support wall sections that are provided so as to be
separated from each other by a space, and a pair of support holes
that are formed in positions in these support wall sections that
are aligned with each other, and is provided so as to face a cam
that is fastened to a camshaft that rotates in synchronization with
the crankshaft of an engine and oscillates and displaces according
to the motion of this cam; a support shaft that, with both ends
sections thereof inserted in the pair of support holes, spans
between the pair of support wall sections and is supported by the
support wall sections; an inner ring member that has an outer
diameter that is larger than the inner diameter of the support
holes, and fits with an interference fit onto the middle section in
the axial direction of the support shaft in a state such that
relative rotation with respect to the support shaft is prevented;
and a tappet roller that is arranged around the inner ring member
so as to be able to rotate relative to the inner ring member.
2. The cam follower apparatus according to claim 1, wherein both
end sections of the support shaft fit with a loose fit into the
pair of support holes so as to be able to rotate on the inside of
the support holes.
3. The cam follower apparatus according to claim 1, wherein a
radial roller bearing is provided between the inner circumferential
surface of the tappet roller and the outer circumferential surface
of the inner ring member.
4. The cam follower apparatus according to claim 3, wherein the
radial roller bearing is a full complement roller bearing.
5. The cam follower apparatus according to claim 4, wherein a pair
of circular ring shaped washers are provided on the inside in the
width direction of the pair of support wall sections so as to cover
the opening sections on both ends of a bearing space of the radial
roller bearing, and have an outer diameter that is greater than the
dimension in the height direction of the support wall sections.
6. The cam follower apparatus according to claim 1, wherein the
inner circumferential surface of the tappet roller comes in sliding
contact with the outer circumferential surface of the inner ring
member.
7. The cam follower apparatus according to claim 1, wherein a
cylindrical shaped member is located between the inner
circumferential surface of the tappet roller and the outer
circumferential surface of the inner ring member so as to be able
to rotate relative to the tappet roller and the inner ring member.
Description
TECHNICAL FIELD
[0001] The present invention relates to a cam follower apparatus
that is assembled in a valve mechanism in the engine of an
automobile and the like.
BACKGROUND ART
[0002] A cam follower apparatus such as disclosed in JP 2006-183856
(A), JP 2005-326023 (A) and the like has been widely used as a
valve mechanism for transmitting the motion of a cam that is
fastened to a camshaft that rotates in synchronization with the
crankshaft of an engine to a valve. FIG. 12 and FIG. 13 illustrate
an example of conventional construction of a cam follower apparatus
as disclosed in JP 2006-183856 (A). A rocker arm 1, which is the
main part of the cam follower apparatus is supported so as to be
able to rotate freely by the cylinder head (not illustrated in the
figure) of the engine by way of a rocker shaft 3 that is inserted
into a shaft hole 2 that is formed in the middle section in the
lengthwise direction thereof. Moreover, by screwing an adjustment
bolt 4 into a screw hole that is formed in the base end section
(left end section in FIG. 12) of the rocker arm 1, and then
tightening a locking nut 5, the adjustment bolt 4 is fastened the
base end section of the rocker arm 1. The base end surface (top end
surface in FIG. 12) of an engine valve 6, which is an air-intake
valve or exhaust valve, that is supported by the cylinder head so
as to be able to move back-and-forth comes in contact with the
tip-end surface (bottom surface in FIG. 12) of the adjustment bolt
4. The engine valve 6 is always forced by a return spring 7 in
closed-valve direction (direction of contact with the adjustment
bolt 4). Therefore, an elastic force in the clockwise direction
around the rocker shaft 3 in FIG. 12 is applied to the rocker arm
1.
[0003] On the other hand, a tappet roller 8 is supported on the
tip-end section (right end section in FIG. 12) of the rocker arm 1
by way of a support shaft 9 so as to be able to rotate freely, and
the outer circumferential surface of the tappet roller 8 comes in
contact with the outer circumferential surface of the cam 10 due to
the elastic force of the return spring 7. A cam 10 is integrally
formed with a camshaft 11 that rotates in conjunction with the
crankshaft (not illustrated in the figure) and is supported by the
cylinder head so as to be able to rotate freely. With this kind of
construction, the rotation of the camshaft 11 is converted to
back-and-forth rocking motion of the rocker arm 1 that is centered
around the rocker shaft 2, and the engine valve 6 is caused to move
back-and-forth in the axial direction by the rocker arm 1 against
the elastic force or due to the elastic force of the return spring
7. This performs the opening/closing operation of the air-intake
port or exhaust port that is provided at the top of the cylinder of
the engine.
[0004] In this kind of valve mechanism, the portion that supports
the tappet roller 8 by way of the support shaft 9 so as to be able
to rotate freely with respect to the rocker arm 1 is constructed as
illustrated in FIG. 13. The support arm 9 spans between a pair of
support wall sections 12 that are provided on the tip-end section
of the rocker arm 1 so as to be parallel with each other and
separated by a space. The tappet roller 8 is supported by a radial
roller (needle) bearing 14 that comprises a plurality of
cylindrical rollers (needles) 13 so as to be able to rotate freely
around a portion in the middle section of the support shaft 9 that
is located between the inside surfaces of the support wall sections
12. Both end sections of the support shaft 9 fit inside and are
supported by circular support holes 15 that are provided in the
support wall sections 12 so as to be concentric with each other. In
this state, by causing the outer circumferential edge sections on
both ends of the support shaft 9 to plastically deform by bringing
the tip-end edge of a crimping jig such as a punch in contact with
a portion near both end surfaces of the support shaft 9, the
support shaft 9 is firmly connected and fastened to the support
holes 15. It is also possible to omit the radial roller bearing 14
and employ single-roller construction or double-roller construction
that allows for relative rotation of cylindrical members between
the inner circumferential surface of the tappet roller and the
outer circumferential surface of the support shaft. This kind of
construction is disclosed in JP 2005-326023 (A), so a detailed
explanation will be omitted here.
[0005] In the case of the first example of conventional
construction illustrated in FIG. 12 and FIG. 13, the middle section
in the lengthwise direction of the rocker arm functions as a
fulcrum, and the tappet roller 8 and adjustment bolt 4 for driving
the engine valve 6 are provided on both end sections. On the other
hand, as illustrated in FIG. 14 and FIG. 15, JP 2009-079569 (A)
discloses construction in which a tappet roller 8a is supported by
a radial roller bearing 14 so as to be able to rotate freely around
a support shaft 9a that is fastened to the middle section in the
lengthwise direction of the rocker arm 1a. Both end section of the
support shaft 9a are fitted inside and supported by circular
support holes 15a that are provided in a pair of support wall
sections 12 so as to be concentric with each other. In the case of
this second example of conventional construction, in the state of
being assembled in the engine, the tip-end section of a lash
adjuster, which is the fulcrum, comes in contact with one surface
on one end section (bottom surface on the left end section in FIG.
14 and FIG. 15) of the rocker arm 1a, and the base end surface of
the engine value comes in contact with one surface on the other end
section (bottom surface of the right end section in FIG. 14 and
FIG. 15).
[0006] In the case of either construction, the outer
circumferential surface in the middle section of the support shaft
9 (9a) functions as an inner-ring raceway of the radial roller
bearing 14 for supporting the tappet roller 8 (8a) so as to be able
to rotate freely, so preferably this outer circumferential surface
in the middle section will not be damaged. Moreover, construction
in which the support shaft 9 (9a) is press fitted into the support
holes 15 (15a) that are formed in the support wall sections 12
(12a) is disadvantageous from the aspect of preventing damage.
Therefore, in order to prevent damage to the outer circumferential
surface of the middle section of the support shaft 9 (9a),
hardening of the entire support shaft 9 (9a) is performed by
immersion quenching in which the entire support shaft 9 (9a) is
heated and then immersed in oil for quenching. However, in the case
of immersion quenching, the entire support shaft 9 (9a) becomes
hard, so when crimping both end section of the support shaft 9
(9a), the tip-end section of the jig, such as a punch, that is
pressed against both end surfaces of the support shaft 9 (9a) could
be damaged, and thus frequent replacement may be necessary. As a
result, processing cost increases, and there is a possibility that
the cost for manufacturing the cam follower apparatus will
increase.
[0007] In regards to this problem, raw portions (unquenched
portions) on both end sections of the support shaft 9 (9a) are
left, and hardening is performed for only the outer circumferential
surface of the middle section with induction hardening. However,
induction hardening itself is a cause for the processing cost to
increase. Moreover, even with both end sections of the support
shaft 9 (9a) raw, the durability of the jig that is used in the
work for crimping and expanding both end sections is limited, and
is not connected to suppressing the processing cost, so even though
induction hardening is performed, it is not completely possible to
sufficiently suppress the manufacturing cost of the cam follower
apparatus.
[0008] Moreover, in the cam follower apparatus having conventional
construction, often, in order to maintain load capacity, a full
complement roller bearing that does not have a cage is used as the
radial roller bearing that is provided between the inner
circumferential surface of the tappet roller 8 (8a) and the outer
circumferential surface in the middle section of the support shaft
9 (9a). In the case of assembling a cam follower apparatus having
this kind of construction, first, a roller assembly in which a
plurality of cylindrical rollers are arranged is assembled in the
space between the inner circumferential surface of the tappet
roller 8 (8a) and the outer circumferential surface of a shaft
member (detent plug) that is located on the inner-diameter side of
the tappet roller 8 (8a).
[0009] Next, the roller assembly is placed between the inside
surfaces in the width direction of the support wall sections 12
(12a) with both end surfaces of the detent plug and the support
holes 15 (15a) in the support wall sections 12 (12a) in an aligned
state. Next, the support shaft 9 (9a) is inserted from the outside
in the axial direction of one of the support wall sections 12 (12a)
into the support hole 15 (15a) of one support wall section 12 (12a)
of the support wall sections 12 (12a). Then, while pressing the
detent plug with the support shaft 9 (a), the support shaft 9 (9a)
is inserted until one end section thereof is inserted into the
support hole 15 (15a) in the other support wall section 12 (12a).
Furthermore, both end section of the support shaft 9 (9a) are
crimped and expanded. In this state, the support shaft 9 (9a) is
supported in a state wherein relative rotation with respect to the
support wall sections 12 (12a) is prevented. In the case of this
kind of construction, the work of inserting the support shaft 9
(9a) into the inner-diameter side of the tappet roller 8 (8a) while
pressing the detent plug is troublesome. Moreover, the number of
parts for assembly and the number of assembly steps increase
because of the use of the detent plug, so the cost increases.
[0010] The outer diameter of the support shaft 9 (9a) and the inner
diameter of the support holes 15 (15a) in the support wall sections
12 (12a) are set based on the diameter of the inscribed circle of
the cylindrical rollers 13 of the radial roller bearing 14.
Therefore, the freedom of design of the support shaft 9 (9a) and
the support wall sections 12 (12a) is low. Furthermore, when the
diameter of the inscribed circle of the cylindrical rollers 13 of
the radial roller bearing 14 is large, it is necessary to make the
overall diameter of the support shaft 9 (9a) large in order to
correspond to the diameter of the inscribed circle. Due to this,
the weight thereof may be increased. In addition, the support shaft
9 (9a) is supported in a state wherein relative rotation with
respect to the support wall sections 12 (12a) is prevented, so load
zone of the support shaft 9 (9a) is limited to a fixed range. In
other words, radial loads that are applied during use are always
applied (supported) in the same location of the support shaft 9
(9a). As a result, repeated loading is applied to the portion of
the support shaft 9 (9a) where radial loading is applied, and there
is a possibility of a decrease in durability. All of the related
technical literature described above is incorporated into this
specification by reference.
RELATED LITERATURE
Patent Literature
[0011] [Patent Literature 1] JP 2006-183856 (A)
[0012] [Patent Literature 2] JP 2005-326023 (A)
[0013] [Patent Literature 3] JP 2009-079569 (A)
SUMMARY OF THE INVENTION
Problem to be Solved by the Invention
[0014] In consideration of the problems described above, it is the
object of the present invention to achieve construction of a cam
follower apparatus that has excellent durability, assembly
characteristics, and freedom of design, is capable of being made
compact and lightweight, and is capable of reducing the
manufacturing cost thereof.
Means for Solving the Problems
[0015] The cam follower apparatus of the present invention has a
rocker arm, a support shaft, an inner ring member and a tappet
roller. The rocker arm has a pair of support wall sections that are
provided so as to be separated from each other by a space, and a
pair of support holes that are formed in positions in these support
wall sections that are aligned with each other, and is provided so
as to face a cam that is fastened to a camshaft that rotates in
synchronization with the crankshaft of an engine and oscillates and
displaces according to the motion of this cam. Moreover, the
support shaft, with both ends sections thereof inserted in the pair
of support holes, spans between the pair of support wall sections
and is supported by the support wall sections. The inner ring
member has an outer diameter that is larger than the inner diameter
of the support holes, and fits with an interference fit onto the
middle section in the axial direction of the support shaft in a
state such that relative rotation with respect to the support shaft
is prevented. Furthermore, the tappet roller is arranged around the
inner ring member so as to be able to rotate relative to the inner
ring member.
[0016] Preferably, both end sections of the support shaft fit with
a loose fit inside the pair of support holes so as to be able to
rotate on the inside of the support holes. Preferably, a radial
roller bearing is provided between the inner circumferential
surface of the tappet roller and the outer circumferential surface
of the inner ring member. In this case, it is preferable that the
radial roller bearing be a full complement roller bearing that does
not have a cage.
[0017] Preferably, in the case where the radial roller bearing is a
full complement roller bearing, a pair of circular ring shaped
washers are provided on the inside in the width direction of the
pair of support wall sections so as to cover the opening sections
on both ends of a bearing space of the radial roller bearing. In
this case, the outer diameter of the washers is greater than the
dimension in the height direction of the support wall sections.
[0018] As the construction of the cam follower apparatus of the
present invention, it is possible to employ double roller
construction in which the inner circumferential surface of the
tappet roller comes in sliding contact with the outer
circumferential surface of the inner ring member. Functionally,
this case is the same as single roller construction. Alternatively,
it is possible to employ triple roller construction in which a
cylindrical member is located between the inner circumferential
surface of the tappet roller and the outer circumferential surface
of the inner ring member so as to be able to rotate relative to the
tappet roller and the inner ring member. Functionally, this case is
the same as double roller construction.
Effect of the Invention
[0019] With the present invention, it is possible to achieve
construction of a cam follower apparatus having excellent
durability, assembly characteristics and freedom of design, and
that is capable of reduced size and weight as well as reduced
manufacturing cost.
[0020] An improvement in durability is due to performing hardening
of the entire support shaft by immersion quenching. In the present
invention, it is not necessary to crimp both end sections of the
support shaft, so it is possible hardening of the support shaft by
immersion quenching. As a result, it is possible to maintain
sufficient strength and rigidity of the entire support shaft, and
to effectively prevent the support shaft from plastically deforming
due to radial loading during use.
[0021] Moreover, in the case of supporting the support shaft so as
to be capable of relative rotation with respect to the support wall
sections, the load zone of the support shaft is not limited to a
fixed range. As a result, it is possible to prevent loads from
being applied to the same location of the support shaft, and thus
it is possible to increase the life of the support shaft.
[0022] Furthermore, even in the case of constructing the radial
bearing using a full complement roller bearing, by providing a pair
of circular ring shaped washers, the inside surfaces in the width
direction of the support wall sections are prevented from rubbing
against the cylindrical rollers, so it is possible to increase the
life of the support wall sections.
[0023] In addition, by reducing the dimension in the height
direction of the support wall sections, it is possible to reduce
the surface area of the portion where the inside surfaces in the
width direction of the support wall sections overlap both end
surfaces in the axial direction of the tappet roller in the axial
direction, and it becomes easier for lubrication oil to penetrate
from the outside into the internal space (bearing space) of the
radial roller bearing.
[0024] Improvement of the assembly characteristics is made possible
by providing the inner ring member. In other words, with a roller
assembly in which an inner ring member, tappet roller and other
components (for example, cylindrical rollers of a radial roller
bearing) are assembled arranged between the support wall sections,
it is possible to perform assembly by inserting the support shaft
in order through the support hole of one support wall section, the
inner circumferential surface of the inner ring member and the
support hole of the other support wall section. Therefore, there is
no need to assemble the support shaft by inserting and pressing out
a detent plug that was located on the inside of the tappet roller
as was done in the conventional construction.
[0025] Improvement of the freedom of design as well is made
possible by proving the inner ring member. In other words, the
outer diameter of the inner ring member can be appropriately set to
correspond to the diameter of the inscribed circle of the
cylindrical rollers of the radial roller bearing, and to set the
inner diameter of the inner ring member to correspond with the
outer diameter of the support shaft and the inner diameter of the
support holes in the support wall sections.
[0026] Reduction in the size and weight is also made possible by
providing the inner ring member. In other words, by changing the
inner diameter of the inner ring member, it is possible to reduce
the outer diameter of the support shaft, so together with being
able to keep the width dimension around the support holes in the
support wall sections in the radial direction of the support holes
at a fixed width, it is possible to reduce the dimension in the
height direction of the support wall sections. As a result, it is
possible to maintain a desired rigidity, and to reduce the size and
weight of the support wall sections and the entire rocker arm.
[0027] Moreover, in the case of providing a pair of circular ring
shaped washers, these washers are able to prevent the cylindrical
rollers of the radial roller bearing from coming out in the axial
direction from the bearing space, so it is possible to further
reduce the dimension in the height direction of the support wall
sections.
[0028] Reduction of the manufacturing cost is possible in that
there is no need to perform crimping work, it is possible to
perform hardening of the support shaft by immersion quenching, and
there is no need for a detent plug.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] FIG. 1 is a drawing illustrating a first example of an
embodiment of the present invention, and corresponds to the section
A-A in FIG. 12 and section B-B in FIG. 14.
[0030] FIG. 2 is a drawing illustrating a second example of an
embodiment of the present invention, and is similar to FIG. 1.
[0031] FIG. 3 is a drawing illustrating a third example of an
embodiment of the present invention, and is similar to FIG. 1.
[0032] FIG. 4 is a drawing illustrating a fourth example of an
embodiment of the present invention, and is similar to FIG. 1.
[0033] FIG. 5 is a drawing as seen from the side in FIG. 4.
[0034] FIG. 6 is a drawing illustrating a fifth example of an
embodiment of the present invention, and is similar to FIG. 1.
[0035] FIG. 7 is a drawing as seen from the side in FIG. 6.
[0036] FIG. 8 is a drawing illustrating a sixth example of an
embodiment of the present invention, and is similar to FIG. 1.
[0037] FIG. 9 is a drawing as seen from the side in FIG. 8.
[0038] FIG. 10 is a drawing illustrating a seventh example of an
embodiment of the present invention, and is similar to FIG. 1.
[0039] FIG. 11 is a drawing as seen from the side in FIG. 10.
[0040] FIG. 12 is a drawing illustrating a first example of a cam
follower apparatus having conventional construction.
[0041] FIG. 13 is an enlarged cross-sectional drawing of section
C-C in FIG. 12.
[0042] FIG. 14 is a side view illustrating a second example of a
cam follower apparatus having conventional construction.
[0043] FIG. 15 is a drawing as seen from the top in FIG. 14.
MODES FOR CARRYING OUT THE INVENTION
First Example
[0044] FIG. 1 illustrates a first example of an embodiment of the
present invention. Features of the cam follower apparatus of the
present invention, including this example, are the construction of
support wall sections 12b, 12c that support a support shaft 9b, and
providing an inner ring 16, which is an inner-ring member, between
the support shaft 9b and the tappet roller 8b. The construction of
the cam follower apparatus other than that of the features of the
present invention, and the assembled state in an engine is the same
as in conventional construction, including that illustrated in FIG.
12 to FIG. 15, so an explanation thereof is omitted or simplified,
so that explanation below centers on the features of this
example.
[0045] The cam follower apparatus of this example has a rocker arm
1b, a support shaft 9b, an inner ring 16, which is an inner-ring
member, a tappet roller 8a and a plurality of cylindrical rollers
13. The rocker arm 1b has a pair of support wall sections 12b, 12c
that are provided in a state being separated by an interval from
each other, and a pair of support holes 15b 15c is formed in
positions in these support wall sections 12b, 12c that are aligned
with each other. In the case of the cam follower apparatus of this
example, both end sections of a hollow or solid steel support shaft
9b are inserted into support holes 15b, 15c in steel support wall
sections 12b, 12c by way of a minute gap (loose fit), and by
spanning between the support wall sections 12b, 12c, the support
shaft 9b is supported such that relative rotation with respect to
the support wall sections 12b, 12c is possible. In other words, the
outer diameter D.sub.9 of the support shaft 9b is a little less
than the inner diameter d.sub.15 of the support holes 15b, 15c
(D.sub.9<d.sub.15).
[0046] In order to sufficiently maintain the strength and rigidity
of the overall support shaft 9b, the support shaft 9b is entirely
hardened by immersion quenching in which the entire support shaft
9b is heated and immersed in quenching oil. However, in hardening
by immersion quenching, the processing cost becomes high, however,
it is also possible to harden the support shaft 9b by induction
hardening in which in the outer circumferential surface in the
middle section is hardened and raw portion remain on both end
sections of the support shaft 9b. Moreover, by performing hardening
such as quenching on inner circumferential surfaces of the support
holes 15b, 15c, it is possible to prevent the occurrence of damage
such as wear to the areas of rubbing between the inner
circumferential surfaces of the support holes 15b, 15c and the
outer circumferential surface of both end sections of the support
shaft 9b. Furthermore, it is possible to provide a ring shaped
sliding bearing member between the outer circumferential surface on
both end sections of the support shaft 9b and the inner
circumferential surfaces of the support holes 15b, 15c. On the
other hand, in this example, it is also possible to employ
construction that prevents rotation of the support shaft 9b with
respect to the support wall sections 12b, 12c by press fitting (fit
using an interference fit) both end sections of the support shaft
9b into the support holes 15b, 15c in the support wall sections
12b, 12c.
[0047] A cylindrical shaped inner ring 16 is fitted onto the outer
circumferential surface of the middle section in the axial
direction of the support shaft 9b with an interference fit so as to
be prevented from relative rotation with respect to the support
shaft 9b (state in which it is possible to rotate together with the
support shaft 9b). The outer diameter D.sub.16 of the inner ring 16
is greater than the inner diameter d.sub.15 of the support holes
15b, 15c (D.sub.16>d.sub.15). In this way, it is possible to
prevent the support shaft 9b from coming out in the axial direction
with respect to the support wall sections 12b, 12c. It is also
possible to provide a large-diameter section that protrudes in the
radial direction around the middle section in the axial direction
of the support shaft, and to have this large-diameter section
function as an inner ring member.
[0048] An inner-ring raceway 17 is formed around the outer
circumferential surface of the inner ring 16. Moreover, a tappet
roller 8b is arranged concentrically around (on the outer diameter
side of) the inner ring 16 such that relative rotation with respect
to the inner ring 16 is possible. An outer-ring raceway 18 is
formed around the inner circumferential surface of the tappet
roller 8b. A radial roller bearing 14a is formed by arranging a
plurality of cylindrical rollers 13 between the inner-ring raceway
17 and the outer-ring raceway 18. In this example, the radial
roller bearing 14a is composed of a full complement roller bearing
in which no cage is provided, however, it is also possible to use
cylindrical rollers with a cage as the cylindrical rollers.
[0049] When assembling the cam follower apparatus of this example,
first, a roller assembly 19 in which the plurality of cylindrical
rollers 13 are arranged is assembled in the space (bearing space
21) between the inner circumferential surface of the tappet roller
8b and the outer circumferential surface of the inner ring 16 that
is provide on the inner-diameter side of the tappet roller 8b.
Next, the roller assembly 19 is placed between the inside surfaces
in the width direction of the support wall sections 12b, 12c in a
state where the opening sections on both end sections in the axial
direction of the inner circumferential surface of the inner ring 16
and the support holes 15b, 15c in the support wall sections 12b,
12c are aligned. Then, the support shaft 9b is inserted through the
support hole 15b in one support wall section 12b of the support
wall sections 12b, 12c from the outside in the width direction of
that one support wall section 12b. While pressing the inner
circumferential surface of the inner ring 16, the support shaft 9b
is further pressed until one end section thereof (left end section
in FIG. 1) is inserted into the support hole 15c in the other
support wall section 12c. In this state, a minute gap is provided
between the outer circumferential surface of both end sections of
the support shaft 9b and the inner circumferential surface of the
support holes 15b, 15c in the support wall sections 12b, 12c. The
assembly direction for assembling the support shaft 9b can also be
the opposite direction.
[0050] In the cam follower apparatus of this example, maintaining
durability is achieved by performing a hardening process using
immersion quenching on the entire support shaft 9b. In other words,
in the case of the cam follower apparatus of the present invention,
by making the outer diameter D.sub.16 of the inner ring 16 greater
than the inner diameter d.sub.15 of the support holes 15b, 15c in
the support wall sections 12b, 12c, it is possible to prevent the
support shaft 9b from coming out in the axial direction with
respect to the support wall sections 12b, 12c. Therefore, it is not
necessary to crimp both end sections of the support shaft 9b, and
it is also not necessary to keep both end sections of the support
shaft 9b in the raw state (state in which hardening is not
performed). Therefore, it is possible to perform hardening of the
support shaft 9b by immersion quenching, in which the entire
support shaft 9b is heated and then immersed in quenching oil. As a
result, it is possible to sufficiently maintain the strength and
rigidity of the entire support shaft 9b, and to effectively prevent
plastic deformation due to radial loading that the support shaft 9b
receives during use.
[0051] Moreover, in the cam follower apparatus of this example, the
support shaft 9b is supported in a state so as to be able rotate
relative to the support wall sections 12b, 12c. Therefore, the load
zone of the support shaft 9b is not limited to a fixed range. In
other words, the location on the support shaft 9b where the radial
load is applied during use is not always the same. As a result, it
is possible to prevent repeated loading to the same location on the
support shaft 9b, and thus it is possible to increase the life of
the support shaft 9b.
[0052] In the cam follower apparatus of this example, improvement
of the assembly characteristics is due to providing the inner ring
16. In other words, with the roller assembly 19 arranged between
the support wall sections 12b, 12c, it is possible to assemble the
support shaft 9b by inserting the support shaft in order through
the support hole 15b in one support wall section 12b, the inner
circumferential surface of the inner ring 16 and the support hole
15c in the other support wall section 12c. Therefore, work to push
a detent plug that is arranged on the inner-diameter side of the
tappet roller 8 (8a) (see FIG. 12 to FIG. 15) out by pressing the
support shaft while inserting it thereinto as was done in the
conventional construction is not necessary.
[0053] In the cam follower apparatus of this example, improvement
of the freedom of design is also achieved by providing the inner
ring 16. In other words, in the conventional construction, the
outer diameter of the support shaft 9 (9a) and the inner diameter
of the support holes 15 (15a) in the support wall sections 12 (12a)
are regulated by the diameter of the inscribed circle of the
cylindrical rollers of the radial roller bearing 14. However, in
the present invention, it is possible to appropriately set the
outer diameter D.sub.16 of the inner ring 16 so as to correspond to
the diameter of the inscribed circle of the cylindrical rollers 13
of the radial roller bearing 14a, and to set the inner diameter
d.sub.16 of the inner ring 16 so as to correspond to the outer
diameter of the support shaft 9b. As a result, it is possible to
improve the freedom of design of the outer diameter of the support
shaft 9b, and the inner diameter of the support holes 15b, 15c of
the support wall sections 12b, 12c.
[0054] As long as the support shaft 3a and support wall sections
4a, 4b can be made more compact as the freedom of design improves
in this way, it is possible to improve the lubrication performance
of the radial roller bearing 14a. In other words, as the diameter
of the support shaft 3a is reduced, the dimension H.sub.12 in the
height direction of the support wall sections 12b, 12c can be
reduced, and it is possible to reduce the area of overlapping
portions with respect to the axial direction between the inside
surfaces in the width direction of the support wall sections 12b,
12c and both end surfaces in the axial direction of the tappet
roller 8b. Therefore, it becomes easy for lubrication oil to
penetrate from the outside through the portion between the inside
surfaces in the width direction of the support wall sections 12b,
12c and both end surfaces in the axial direction of the tappet
roller 8b and enter inside the bearing space 21 where cylindrical
rollers of the radial roller bearing are located.
[0055] In the cam follower apparatus of this example, reducing the
size and weight are achieved by proving the inner ring 16. In other
words, in order to maintain a desired rigidity of the support wall
sections 12b, 12c, it is necessary to maintain a specified width
dimension L.sub.12 of the support wall sections 12b, 12c around the
support holes 15b, 15c with regard to the radial direction of the
support holes 15b, 15c. In this example, by changing the inner
diameter d.sub.16 of the inner ring 16, it is possible to reduce
the outer diameter D.sub.9 of the support shaft 9b. Therefore, it
is possible to reduce the dimension H.sub.12 in the height
direction (up-down direction in FIG. 1) of the support wall
sections 12b, 12c, while keeping the width dimension of the support
wall sections 12b, 12c around the support holes 15b, 15c with
regard to the radial direction of the support holes 15b, 15c. As a
result, it is possible to reduce the size and weight of the support
wall sections 12b, 12c and the entire rocker arm 1b.
[0056] Furthermore, in the construction of the cam follower
apparatus of this example, crimping work is not necessary, and thus
a jig such as a punch or the like for forming the crimped sections
is not necessary. Moreover, the hardening process for hardening the
support shaft 9b is performed by immersion quenching, which is
lower in cost than induction hardening. Furthermore, there is no
need for a detent plug during assembly. As a result of these, it is
possible to reduce the processing cost and parts cost, as well as
it is possible to reduce the overall manufacturing cost of the cam
follower apparatus.
Second Example
[0057] FIG. 2 illustrates a second example of an embodiment of the
present invention. In the case of the cam follower apparatus of
this example, the outer circumferential surface of the inner ring
16a that is fitted around the outer circumferential surface of the
middle section in the axial direction of the support shaft 9b comes
in sliding contact with the inner circumferential surface of the
tappet roller 8b that is provided in a state so as to be able to
rotate relative to the inner ring 16a. The shape and dimensions of
the tappet roller 8b are the same as in the first example of an
embodiment.
[0058] In other words, the cam follower apparatus of this example
has so-called double roller construction in which the radial roller
bearing 14a in the first example of an embodiment is omitted.
However, the inner ring 16a of the cam follower apparatus of this
example is similar to the inner ring 16 of the first example of an
embodiment in that the inner ring 16a fits with an interference fit
around the outer circumferential surface of the middle section in
the axial direction of the support shaft 9b in a state so as to be
able to rotate together with the support shaft 9b (prevented from
relative rotation with respect to the support shaft 9b). Therefore,
from a functional aspect, the cam follower apparatus of this
example functions as a so-called single-roller cam follower
apparatus. The other construction, functions and effects of this
example are the same as in the first example of an embodiment.
Third Example
[0059] FIG. 3 illustrates a third example of an embodiment of the
present invention. In the case of the cam follower apparatus of
this example, an inner-diameter side roller 20, which is a
cylindrical member, is provided between the outer circumferential
surface of the inner ring 16 that is fitted around the outer
circumferential surface of the middle section in the axial
direction of the support shaft 9b and the inner circumferential
surface of the tappet roller 8b in a state so as to be able to
rotate relative to the inner ring 16 and the tappet roller 8b. The
shape and dimensions of the tappet roller 8b and inner ring 16 are
the same as in the first example of an embodiment.
[0060] In other words, the cam follower apparatus of this example
has so-called triple roller construction in which an inner-diameter
side roller 20 is provided instead of the radial roller bearing 14a
of the first example of an embodiment. However, as in the first
example of an embodiment, the inner ring 16 of the cam follower
apparatus of this example is fitted around the outer middle section
in the axial direction of the support shaft 9b in a state such that
relative rotation with respect to the support shaft 9b is prevented
(rotation with the support shaft 9b is possible). Therefore, from a
functional aspect, the cam follower apparatus of this example
functions as a so-called double roller cam follower apparatus. The
other construction, functions and effects of this example are the
same as in the first example of an embodiment.
Fourth Example
[0061] FIG. 4 and FIG. 5 illustrate a fourth example of an
embodiment of the present invention. In the case of the cam
follower apparatus of this example, a pair of circular ring shaped
washers 22 made using a hard metal or a synthetic resin is provided
in the axial direction between the inside surfaces in the width
direction of the pair of support wall sections 12d, 12e and both
end surfaces in the axial direction of the inner ring 16. Moreover,
the outer diameter D.sub.22 of the washers 22 is greater than the
inner diameter d.sub.8 of the tappet roller 8b
(D.sub.22>d.sub.8). In other words, the washers 22 are provided
in a state so as to cover the opening sections on both ends in the
axial direction of the bearing space 21 where the cylindrical
rollers 13 of the radial roller bearing 14a are located. In this
example, the diameter D.sub.22 of the washers 22 is greater than
the dimension H.sub.12d in the height direction (up-down direction
in FIG. 4 and FIG. 5) of the support wall sections 12d, 12e
(D.sub.22>H.sub.12d).
[0062] With the cam follower apparatus of this example, it is
possible to reduce the size and the weight more than with the
construction of the first example of an embodiment. In other words,
in the case of this example, with the washers 22, the opening
section on both ends in the axial direction of the bearing space 21
are covered, and the cylindrical roller 13 are prevented from
coming out in the axial direction from the bearing space 21.
Therefore, there is no need to prevent the cylindrical rollers 13
from coming out in the axial direction by the support wall sections
12d, 12e. As a result, it is possible to reduce the dimension
H.sub.12d in height direction of the support wall sections 12d,
12e, and it is possible to reduce the size and weight of the rocker
arm, including the support wall sections 12d, 12e.
[0063] Moreover, in the case of this example, the washers 22 cover
the opening sections on both ends in the axial direction of the
bearing space 21. Therefore, wear due to the inside surfaces in the
width direction of the support wall sections 12d, 12e rubbing
against the rollers 13 of the radial roller bearing 14a is
prevented, and thus it is possible to increase the life of the
support wall sections 12d, 12e. The other construction, functions
and effects of this example are the same as in the first example of
an embodiment.
Fifth Example
[0064] FIG. 6 and FIG. 7 illustrate a fifth example of an
embodiment of the present invention. In the case of the cam
follower apparatus of this example, the dimension L.sub.16b in the
axial direction of the inner ring 16b is larger than the dimension
L.sub.16 in the axial direction of the inner ring 16 (see FIG. 1)
of the first example of an embodiment (L.sub.16b>L.sub.16). On
the other hand, the shape and dimensions of the tappet roller 8b
are the same as in the first example of an embodiment. Therefore,
both end sections in the axial direction of the inner ring 16b are
located further on the outside in the width direction than both end
sections in the axial direction of the tappet roller 8b.
[0065] Moreover, further on the inside in the width direction than
the inside surfaces in the width direction of the support wall
sections 12d, 12e, a pair of circular ring shaped washers 22a are
provided on both end sections in the axial direction of the outer
circumferential surface of the inner ring 16b (portions further on
the outside in the width direction than both end surfaces in the
axial direction of the tappet roller 8b). The outer diameter
D.sub.22a of the washers 22a is larger than the inner diameter
d.sub.8 of the tappet roller 8b (D.sub.22a>d.sub.8). Therefore,
the washers 22a are provided in a state so as to cover the opening
sections on both ends in the axial direction of the bearing space
21 in which the cylindrical rollers 13 of the radial roller bearing
14b are located.
[0066] In this example as well, the outer diameter D.sub.22a of the
washers 22a is larger than the dimension H.sub.12d in the height
direction (up-down direction in FIGS. 6 and 7) of the support wall
sections 12d, 12e (D.sub.22a>H.sub.12d). The other construction,
functions and effect of this example are the same as in the fourth
example of an embodiment.
Sixth Example
[0067] FIG. 8 and FIG. 9 illustrate a sixth example of an
embodiment of the present invention. In the case of the cam
follower apparatus of this example, the dimension L.sub.8c in the
axial direction of the tappet roller 8c is greater than the
dimension L.sub.8 in the axial direction of the tappet roller 8b in
the first example of an embodiment (L.sub.8c>L.sub.8). On the
other hand, the shape and dimensions of the inner ring 16 are the
same as in the first example of an embodiment. Therefore, both end
sections in the axial direction of the tappet roller 8c are located
further on the outside in the width direction than both end
sections in the axial direction of the inner ring 16.
[0068] Moreover, on the inner diameter side of both end sections in
the axial direction (in portions further on the outside in the
width direction than both end surfaces in the axial direction of
the inner ring 16) of the tappet roller 8c, and between the inside
surfaces in the width direction of the support wall sections 12d,
12e and the both end sections in the axial direction of the inner
ring 16 with regard to the axial direction of the outer
circumferential surface of the support shaft 9b, a pair of circular
ring shaped washers 22b are provided. The outer diameter D.sub.22b
of the washers 22b is a little less than the inner diameter d.sub.8
of the tappet roller 8c (D.sub.22b<d.sub.8). In other words, the
washers 22b are provided in a state so as to cover the opening
sections on both ends in the axial direction of the bearing space
21 in which the cylindrical rollers 13 of the radial roller bearing
14 are located.
[0069] In the case of this example as well, the outer diameter
D.sub.22b of the washers 22 is greater than the dimension H.sub.12d
in the height direction of the support wall sections 12d, 12e
(D.sub.22b>H.sub.12d). The other construction, functions and
effects of this example are the same as in the fourth example of an
embodiment.
Seventh Example
[0070] FIG. 10 and FIG. 11 illustrate a seventh example of an
embodiment of the present invention. In the case of the cam
follower apparatus of this example, the inner ring 16b of the fifth
example of an embodiment (see FIG. 6), and the tappet roller 8c of
the sixth example of an embodiment (see FIG. 8) are combined to
form a radial roller bearing 14d. In other words, in this example,
the dimension L.sub.8c in the axial direction of the tappet roller
8c is greater than the dimension L.sub.8 in the axial direction of
the tappet roller 8b of the first example of an embodiment
(L.sub.8c>L.sub.8), and the dimension L.sub.16b in the axial
direction of the inner ring 16b is greater than the dimension
L.sub.16 in the axial direction of the inner ring (see FIG. 1) of
the first example of an embodiment (L16b>L16). The dimension in
the axial direction of the tappet roller and inner ring can be the
same as in the first example of an embodiment, and the dimension in
the axial direction of the cylindrical rollers can be less than
that of the cylindrical rollers 13 of the first example of an
embodiment (see FIG. 1).
[0071] Moreover, a pair of circular ring shaped washers 22c are
provided between both end sections in the axial direction of the
outer circumferential surface of the inner ring 16b and both end
sections in the axial direction of the inner circumferential
surface of the tappet roller 8c. In other words, the washers 22c
are provided in a state so as to cover the opening sections on both
ends in the axial direction of the bearing space 21 in which the
cylindrical rollers 13 of the radial roller bearing 14d are
located. In this example, it is also possible to use a cage instead
of the washers 22c.
[0072] In this example as well, the outer diameter D.sub.22c of the
washers 22c is greater than the dimension H.sub.12d in the height
direction (up-down direction in FIGS. 10 and 11) of the support
wall sections 12d, 12e (D.sub.22c>H.sub.12d). The other
construction, functions and effects of this example are the same as
in the fourth example of an embodiment.
EXPLANATION OR REFERENCE NUMBERS
[0073] 1, 1a, 1b Rocker arm
[0074] 2 Shaft hole
[0075] 3 Rocker shaft
[0076] 4 Adjustment bolt
[0077] 5 Locking nut
[0078] 6 Engine value
[0079] 7 Return spring
[0080] 8, 8a, 8b Tappet roller
[0081] 9, 9a, 9b, 9c Support shaft
[0082] 10 Cam
[0083] 11 Cam shaft
[0084] 12, 12a, 12b, 12c, 12d, 12e Support wall section
[0085] 13 Cylindrical roller
[0086] 14, 14a, 14b, 14c, 14d Radial roller bearing
[0087] 15, 15a, 15b, 15c, 15d, 15e Support hole
[0088] 16, 16a, 16b Inner ring
[0089] 17 Inner-ring raceway
[0090] 18 Outer-ring raceway
[0091] 19 Roller assembly
[0092] 20 Inner-diameter side roller
[0093] 21 Bearing space
[0094] 22, 22a, 22b, 22c Washer
* * * * *