JPH06331003A - Cam follower - Google Patents

Abstract

PURPOSE:To smooth lubricating oil to supplying between a roller and a supporting shaft so as to ensure lubricating property by constituting a cam follower by fitting rotatably the roller divided into two parts at minute space in axial direction on the metal made supporting shaft of a driven member. CONSTITUTION:A roller which is brought in contact with a cam in an engine and which is a cam invertor for driving a valve supported between a pair of parallel rocker arms R and R by a supporting shaft 2, consists of rollers 1A and 1B which are divided into two parts in axial direction and which fit- supported rotatably on the supporting shaft 2. Suitable minute spaces 3 are formed between the outer side end surface of the rollers 1A, 1B and both side surface of a roller hole H, between both inner side end surfaces of the rollers 1A, 1B, and between the inner circumferential surface of the roller 1A, 1B and the outer circumferential surface of the supporting shaft 2. The roller 1A, 1B are made of ceramic, and a projection part for ensuring minute space is formed on at least one of the opposing end surface of a rotor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cam follower, for example, a cam follower for driving a valve of an engine.

[0002]

2. Description of the Related Art In an engine as shown in FIG. 4, a roller 1 of a rocker arm R contacting a cam C is freely rotatable on a rocker arm R by a metal support shaft 2 as shown in FIG. It is configured to be supported by.

Since friction between the outer peripheral surface of the support shaft 2 and the inner peripheral surface of the roller 1 causes severe wear of both, in order to improve lubricity between the both, the inner peripheral surface of the roller 1 to some extent. With controlled roughness, the knurling process is performed to retain the lubricating oil. Further, in order to reduce the weight of the roller 1 and wear resistance thereof, particularly seizure resistance and wear resistance of the inner peripheral surface thereof, the roller 1 may be made of ceramics.

[0004]

As described above, the problem of the greatest deterioration occurs in the lubrication state between the inner peripheral surface of the roller of the rocker arm for driving the engine valve and the outer peripheral surface of the support shaft. Problems such as baking occur.

In response to this, a roller of a rocker arm for driving a valve of an engine of the prior art is a roller for improving lubricity between an inner peripheral surface of the roller and an outer peripheral surface of a support shaft. The inner peripheral surface is roughened such as knurling so that the lubricating oil is retained, but the supply of the lubricating oil over the entire surface is not sufficient and the roughening is troublesome.

When the roller is made of ceramics, seizure resistance and wear resistance on the roller side are good, but wear on the support shaft side becomes more problematic.
It is not possible to apply rough surface processing such as knurling to the inner surface of the roller.

An object of the present invention is to solve the above-mentioned lubrication problem of a roller and a support shaft in a cam follower, for example, a cam follower for driving a valve of an engine.

[0007]

The cam follower of the present invention is divided into a plurality of parts so that a minute gap can be formed in the axial direction on the metal support shaft of the follower member (eg rocker arm), and the cam follower is The engaging roller is rotatably fitted and supported, and preferably, a protrusion is formed on at least one of the opposite end surfaces of the roller.

Further, the roller may be made of ceramics. In that case, it is preferable to rotatably fit a metal sleeve engaging with a cam to the outer peripheral surface of the roller.

[0009]

In the cam follower described above, the roller, that is, the cam follower is pressed and displaced as the cam rotates,
The driven member is displaced. At that time, the roller rotates around the support shaft. When the rollers are rotated, even if the rollers are not processed, the lubricating oil is not only a minute gap between the rollers and the outer end surface of the rollers, but also a minute gap between the rollers, that is, between the opposite end surfaces of the rollers. The lubricating oil is also supplied to and held between the inner peripheral surface of the roller and the outer peripheral surface of the support shaft, so that lubrication between the both is sufficiently performed. Therefore, wear of the roller and the support shaft, especially the support shaft, is suppressed.

Further, when the protrusions are formed on the opposite end faces of the roller, the minute gap between the opposite end faces of the roller is surely maintained. Therefore, the supply of the lubricating oil from the minute gap between the inner peripheral surface of the roller and the outer peripheral surface of the support shaft is ensured, that is, the wear of the roller and the support shaft, particularly the support shaft, is surely suppressed.

If the roller is made of ceramics,
Since the wear resistance of the roller is improved and the driven member is reduced in weight, the responsiveness is improved. When the sleeve is fitted over the sleeve, the sleeve prevents the ceramic roller from being damaged, and the sleeve prevents scattering of the broken pieces even when the roller is damaged.

Even if there is a temperature change, that is, even if there is a difference in expansion between the metal support shaft / sleeve and the ceramic roller, when the roller / sleeve rotates, the outer peripheral surface of the support shaft and the roller The sum of the minute gap between the peripheral surface and the minute gap between the outer peripheral surface of the roller and the inner peripheral surface of the sleeve can be maintained at a constant amount. Therefore, the lubricating oil is kept flowing in these minute gaps, that is, the lubrication between the outer peripheral surface of the support shaft and the inner peripheral surface of the roller and the lubrication between the outer peripheral surface of the roller and the inner peripheral surface of the sleeve are maintained.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A cam follower according to an embodiment of the present invention will be described with reference to the drawings. As the cam follower, the roller 1 of the rocker arm R that contacts the cam C in the engine shown in FIG. 4 will be described as an example.

In FIG. 4, one end (right end) of a rocker arm R made of metal is supported by a spherical fulcrum P, and a tappet valve V is attached to the other end (left end). A roller hole H into which the roller 1 that engages with the cam C is fitted is formed in the central region of the rocker arm R, and the metal is attached to both arm portions of the roller hole H while being supported at both ends by caulking or the like. A roller 1 is rotatably supported on a manufactured support shaft 2. The sliding surface of the support shaft 2 is subjected to heat treatment such as quenching.

In the first embodiment shown in FIG. 1, a hollow roller 1 is rotatably fitted and supported on a support shaft 2 and divided into two axially divided rollers 1A and 1B, that is, two adjacent rollers. The divided rollers 1A and 1B are provided so that the divided rollers 1A and 1B have an appropriate play in the roller hole H in the axial direction. Therefore, the roller hole H
Between the both side surfaces of the divided rollers 1A and 1B, the outer end surfaces of the divided rollers 1A and 1B, the inner end surfaces of the divided rollers 1A and 1B, and the inner peripheral surface of the divided rollers 1A and 1B and the outer peripheral surface of the support shaft 2. An appropriate minute gap 3 can be formed.

The material of the split rollers 1A and 1B is generally metal, but in some cases, it may be a ceramic material.
Further, it is preferable to chamfer both end edges of the outer peripheral surface and the inner peripheral surface of the split rollers 1A and 1B, or to form them into an arc surface. By doing so, the influence of wear on the support shaft 2 is reduced, and the inclination of the split rollers 1A and 1B can be dealt with.

In the second embodiment shown in FIG. 2, at least one of the two split rollers 1A and 1B in the first embodiment is divided into the other split roller 1A (1B).
An appropriate number of small protrusions 4 are formed on the end surface facing B (1A). In the illustrated example, the three small protrusions 4, 4,
4 are formed at equal intervals on the circumference. And the small protrusion 4 is
It can come into contact with the end faces of the other opposing roller to prevent contact between the opposing end faces of both rollers, and maintain the minute gap 3 between the split rollers 1A and 1B.

In the third embodiment shown in FIG. 3, the roller of the first embodiment and the roller 1 of the second embodiment (split roller 1
A, 1B) is made of ceramics, and a cylindrical sleeve 5 made of metal is rotatably fitted and supported on the outer peripheral surfaces of the split rollers 1A, 1B.
The outer peripheral surface of is engaged with the cam C. An appropriate minute gap 6 may be formed between the outer peripheral surface of the roller 1 and the inner peripheral surface of the sleeve 5. At least the inner and outer peripheral sliding surfaces of the sleeve 5 are subjected to hardening treatment such as quenching. The thickness of the sleeve 5 is preferably thinner than that of the roller 1 within a range that does not impair strength in terms of weight reduction. Further, both end surfaces of the ceramic split rollers 1A and 1B may be roughened surfaces that have been sintered and finished for the purpose of retaining lubricating oil.

In the rocker arm R of the above-described embodiment, the roller 1 is pressed and displaced in accordance with the rotation of the cam C, whereby the rocker arm R swings around the fulcrum, and the tappet valve V accordingly moves. It is opened and closed. At that time, the roller 1 rotates around the support shaft 2.

In the rotation of the roller 1, even if the roller 1 is not processed, the lubricating oil is not limited to the minute gap 3 between the both side surfaces of the roller hole H and the outer end surfaces of the divided rollers 1A and 1B. 1 central part, that is, the split rollers 1A, 1
The lubricating oil is supplied and held in the minute gap 3 between the opposite end surfaces of B, and the lubricating oil is also supplied from there between the inner peripheral surface of the roller 1 and the outer peripheral surface of the support shaft 2, so that the lubrication between the two is sufficient. To be done. Therefore, wear of the roller 1 and the support shaft 2, especially the support shaft 2, is suppressed.

Further, as in the case of the second embodiment, when the small projection 4 is formed on the end surface facing the split roller 1B (1A), the minute gap 3 between the facing end surfaces of the split rollers 1A, 1B becomes small. Will be maintained reliably. Therefore, the supply of the lubricating oil from the minute gap 3 between the inner peripheral surface of the roller 1 and the outer peripheral surface of the support shaft 2 is ensured, that is, the roller 1 and the support shaft 2, especially the support shaft 2
Deterrence of wear and tear on the will be ensured.

When the split rollers 1A and 1B are made of ceramics, the wear resistance of the roller 1 is improved and the clearance adjustment of the tappet valve becomes unnecessary. Since the device is lightened, the responsiveness of the engine and the fuel consumption performance are improved. Further, in the case of the third embodiment, the divided rollers 1A and 1B made of ceramics by the sleeve 4 fitted on the outside.
Even if an accident occurs in which the split rollers 1A, 1B are damaged, the sleeve 4 prevents the risk of scattering the fragments.

Even if there is a temperature change in the engine, that is, there is a difference in expansion between the support shaft 2, the roller 1 and the sleeve 4, when the roller 1 and the sleeve 4 rotate, the outer peripheral surface of the support shaft 2 and the roller 4 rotate. The sum of the minute gap 3 between the inner peripheral surfaces of the roller 1 and the minute gap 6 between the outer peripheral surface of the roller 1 and the inner peripheral surface of the sleeve 5 can be maintained at a constant amount. Therefore, the lubricating oil is kept flowing in the minute gaps 3 and 6, that is, the lubrication between the outer peripheral surface of the support shaft 2 and the inner peripheral surface of the roller 1 and the lubrication between the outer peripheral surface of the roller 1 and the inner peripheral surface of the sleeve 5. Maintained.

[0024]

According to the cam follower of the present invention, it is not necessary to perform a troublesome roughening process only by dividing the roller in the axial direction, and the inner peripheral surface of the roller and the outer peripheral surface of the support shaft are separated from each other. Sufficient supply / holding of the lubricating oil to / from the space is realized, the lubrication between the two is sufficiently performed, and the wear of both, especially the spindle is suppressed.

Moreover, since no special rough surface processing is required and sufficient lubrication is carried out, there is no fear of wear of the support shaft, the accuracy of the cam follower is maintained by improving the wear resistance of the roller, and the weight of the roller is light. It is possible to use a roller made of ceramics, which has many advantages such as improvement in responsiveness of the cam follower due to the use of a roller. When the sleeve is externally fitted, the ceramic roller is further prevented from being damaged, and the risk of scattering of debris when the roller is damaged is prevented.

[Brief description of drawings]

FIG. 1 is a sectional view of a roller of a rocker arm of an engine according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a roller of a rocker arm of an engine according to a second embodiment of the present invention.

FIG. 3 is a perspective view of a split roller of a rocker arm of an engine according to a third embodiment of the present invention.

FIG. 4 is a partial cross-sectional view of a rocker arm of the engine.

FIG. 5 is a sectional view of a roller of a rocker arm of an engine according to a conventional technique.

[Explanation of symbols]

 R Rocker arm P Spherical fulcrum V Tappet valve C Cam H Roller hole 1 Roller 1A, 1B Divided roller 2 Support shaft 3,6 Micro gap 4 Small protrusion 5 Sleeve

Claims (4)

[Claims] 1. A cam follower in which a metal supporting shaft of a driven member is divided into a plurality of parts so as to form a minute gap in the axial direction, and a roller engaging with the cam is rotatably fitted and supported. . 2. The cam follower according to claim 1, wherein a projection is formed on at least one of the opposing end faces of the roller. 3. The roller is made of ceramics.
Alternatively, the cam follower according to claim 2. 4. The cam follower according to claim 3, wherein a metal sleeve engaging with the cam is rotatably fitted to the outer peripheral surface of the roller.