JPH06331002A - Cam follower - Google Patents

Abstract

PURPOSE:To dissolve braking, temperature change, and the like in a case of using a ceramic made roller in which there is an advantage in a cam invertor. CONSTITUTION:A cam follower consists of a ceramic made hollow roller member 11 which is fit and supported rotatably on the metal made supporting shaft of a driven member A, and a metal made sleeve 12 which is fit and supported rotatably on the outer circumferential surface of the hollow roller member 11 and whose outer circumferential surface is engaged with a cam, and the suitable number of ceramic made needle rollers may be used instead of the ceramic made hollow roller member.

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 A cam follower for driving a valve of an engine of the prior art is constructed by a rocker arm rotatably supporting a roller member as a portion in contact with the cam with a metal support shaft.

[0003]

The cam follower for driving the valve of the engine according to the above-mentioned conventional technique has a disadvantage that it is heavy because it is made of metal, and the inner peripheral surface of the roller member and the support shaft are not supported. The problem of deterioration is most likely to occur between the outer peripheral surface and the outer peripheral surface, and problems such as baking occur at this portion.

Therefore, in order to deal with the problem of lubrication between the support shaft and the roller member, it is possible to use a ceramic material for the roller member, which is lightweight and has excellent seizure resistance. In that case, the following new problems will become obstacles and their use will not be appropriate.

(1) Since the ceramic material is a brittle material, the roller member may be damaged during operation and use.
It causes a fatal trouble. (2) Due to the difference in coefficient of thermal expansion between the ceramic material and the metal, the clearance between the inner peripheral surface of the roller member and the outer peripheral surface of the support shaft becomes narrow during operation and use, resulting in poor lubrication and abnormal wear of the metal shaft. May occur or, in the worst case, the roller member may be locked. An object of the present invention is to provide a cam follower that solves the above problems of the ceramic roller member.

[0006]

SUMMARY OF THE INVENTION A cam follower of the present invention is rotatably fitted and supported by a metal support shaft of a driven member and is rotated by a ceramic hollow roller member and an outer peripheral surface of the hollow roller member. It is freely fitted and supported, and its outer peripheral surface is composed of a metal sleeve that engages with a cam. Even if an appropriate number of ceramic needle rollers are used instead of the ceramic hollow roller member. Good.

[0007]

In the cam follower, the sleeve, that is, the cam follower is pressed and displaced as the cam rotates, whereby the follower member is displaced. At that time, the sleeve or the hollow roller member rotates around the support shaft. The sleeve prevents the ceramic hollow roller member from being damaged, and even if an accident occurs in which the ceramic hollow roller member is damaged, the sleeve prevents scattering of the fragments.

[0008]

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, a rocker arm A including a roller 1 that contacts the cam C in the engine shown in FIG. 2 will be described as an example.

In FIG. 2, one end (right end) of a rocker arm A 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 A, and a metal support supported by both ends of the arm portions on both sides of the roller hole H is attached. A roller 1 is rotatably supported on the shaft 2.

Roller 1 in the first embodiment shown in FIG.
Is a hollow roller member 11 made of ceramics rotatably fitted and supported on the support shaft 2, and rotatably fitted and supported on the outer peripheral surface of the hollow roller member 11, and the outer peripheral surface is engaged with the cam C. And a sleeve 12 made of steel.

The gap between the outer peripheral surface of the hollow roller member 11 and the inner peripheral surface of the sleeve 12 is 1/100 to 2 of the gap between the inner peripheral surface of the hollow roller member 11 and the outer peripheral surface of the support shaft 2. / 100
mm, the gap between the outer peripheral surface of the hollow roller member 11 and the inner peripheral surface of the sleeve 12, the inner peripheral surface of the hollow roller member 11 and the support shaft 2
The sum of the gap with the outer peripheral surface of the is 6/100 to 15/1.
It is 00 mm.

The length of the hollow roller member 11 is shorter than the length of the sleeve 12 by about 5/10 mm.
Both end surfaces of 11 are as-sintered, that is, rough surfaces.

In the second embodiment, the hollow roller member 11
Instead of, the appropriate number of needle rollers made of ceramics are fitted between the outer peripheral surface of the support shaft 2 and the inner peripheral surface of the sleeve 12 like a rolling element of a bearing.

In the above rocker arm A, the cam C
When the sleeve 12, that is, the roller 1 is displaced by being rotated in accordance with the rotation, the rocker arm A swings around the spherical fulcrum P, and the tappet valve V is opened / closed accordingly. At that time, the roller 1 rotates around the support shaft 2.

In the rotation of the roller 1, even if there is a difference in expansion between the support shaft 2, the hollow roller member 11 and the sleeve 12, the rotation of the hollow roller member 11 on the outer peripheral surface of the support shaft 2 at a low temperature due to the gap difference. When the temperature is high, the hollow roller member
The sleeve 12 is rotated on the outer peripheral surface of 11. Therefore, the roller 1 can rotate stably even when the temperature changes in a wide range.

Further, the lubricating oil is retained in the circumferential gaps of the three members, and at both ends of the hollow roller member 11, the lubricating oil retaining effect is produced by the gap due to the short dimension of the hollow roller member 11 and the roughened end surface. Smooth rotation can be obtained. Thus, the tappet valve operates stably and smoothly even when the temperature changes over a wide range.

Moreover, since the both end surfaces of the hollow roller member 11 remain as sintered and are not further finished, the manufacturing cost is reduced. Then, the sleeve 12 prevents the ceramic hollow roller member 11 from being damaged,
Even if the ceramic hollow roller member 11 is damaged, the sleeve 12 prevents the scattering of fragments.

In the case of the second embodiment as well, it is easily understood that the stable and smooth rotation of the roller 1 can be obtained as in the first embodiment and the accident of the needle roller 13 can be dealt with. Will be done.

[0019]

According to the present invention, in the cam follower,
Since the rotating member made of ceramics is used for the metal support shaft, seizure resistance is improved due to good lubricity and high-speed followability is improved due to weight reduction. Moreover,
The problem that the rotating member is made of ceramics is solved. That is, the metal sleeve prevents the ceramic rotating member from being damaged, and prevents troubles when the ceramic rotating member is damaged.

[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 rocker arm of the engine in the first embodiment of the present invention.

[Explanation of symbols]

 1 Roller 11 Hollow roller member 12 Sleeve 2 Spindle A Rocker arm C Cam P Spherical fulcrum V Tappet valve

Claims (2)

[Claims] 1. A hollow roller member made of ceramics, which is rotatably fitted and supported by a metal support shaft of a driven member, and rotatably fitted and supported by an outer peripheral surface of the hollow roller member, the outer peripheral surface of which is a cam. And a cam follower configured to engage with the metal sleeve. 2. A cam follower configured such that a metal sleeve having an outer peripheral surface engaging with a cam is rotatably fitted and supported via a needle roller made of ceramics on a metal support shaft of a driven member. Child.