GB2250560A

GB2250560A - Cam followers for internal combustion engines

Info

Publication number: GB2250560A
Application number: GB9026523A
Authority: GB
Inventors: Brian Kenneth Brown; Graham Beck
Original assignee: Individual
Current assignee: Individual
Priority date: 1990-12-06
Filing date: 1990-12-06
Publication date: 1992-06-10
Also published as: GB9026523D0

Abstract

A cam follower for an internal combustion engine, the cam follower comprising a body shaped at one end to define a cam following surface 6 and recessed at its other end 9 to receive and retain one end of a push rod, the body including through passageways 4 for the flow of lubricant. <IMAGE>

Description

Improvements in and relating to Cam Followers for Internal Combustion Engines This invention relates to cam followers for use in internal combustion engines.

Cam followers are, of course, well known for translating rotational movement of a cam shaft into the linear movement required to open and close the valves of an internal combustion engine. Typically, cam followers are positioned between one of several cams of a cam shaft and a respective push rod connected at its other end to a rocker which moves to open and close the valves against the action of suitably positioned coil springs. Cam followers are conventionally of complex construction, one such follower comprising a sleeve which houses a roller disc supported by an H frame which seats within the sleeve, the sleeve being secured to the cylinder head of the engine by means of a bolt. Such a cam follower has been found to be prone to wear and breakage.

The present invention sets out to provide a cam follower which is of relatively simple construction and which does not suffer from or at least alleviates the problems referred to above.

According to the present invention in one aspect, there is provided a cam follower for an internal combustion engine, the cam follower comprising a body shaped at one end to define a cam following surface and recessed at its other end to receive and retain one end of a push rod, the body including through passageways for the flow of lubricant, e.g. oil.

The cam follower body may be generally circular in cross-section with the cam following surface spaced forwardly of the main body portion and symmetrically about the longitudinal axis of the body. The cam following surface may be present on the forward end of an extension piece of the main body portion, the extension piece protruding from the central slug of the body with a waist interposed between the slug and the extension piece.

The passageways are preferably aligned generally parallel to the longitudinal axis of the body in an array about the central slug of the body. Eight such passageways may be symmetrically positioned about the slug of the body.

The recess may be formed in the end of the slug remote from the extension piece and the outer periphery of the body portion may extend beyond the end of the slug whereby the recess is positioned within the confines of the body.

A series of holes may be formed in the outer surface of the cam follower, these holes communicating with one or more of the lubricant flow passageways.

In another aspect, the invention provides a generally cylindrical cam follower including a plurality of longitudinally extending lubricant flow passageways disposed about a central slug, the slug being formed at one end with a cam following surface end at its other end with a recess into which one end of a push rod can seat.

The invention will now be described by way of example only with reference to the accompanying diagrammatic drawings in which: Figures 1 and 2 are opposite end views of a cam follower in accordance with the invention; and Figure 2 is a section taken along line III-III of Figure 1.

The cam follower illustrated in the drawings is produced as a single piece of, for example, an aluminium zinc compound, e.g. that known as ZA 27, and comprises a body 1 including a central slug 2 from one end of which projects an extension piece 3. A series of through passageways 4 pass through the body 1, these passageways being symmetrically disposed about the slug and extending generally parallel to the longitudinal axis of the body.

The end face 6 of the extension piece of the slug defines a cam following surface which, in use of the cam follower lies in contact with and follows one of several cams located on a cam shaft of an internal combustion engine.

As shown, a waist 7 is provided between the cam following surface 6 of the extension piece 3 and the main body of the plug 2. The external diameter of the end face 6 is less than that of the body 1. This, together with the presence of the waist 7, ensures an uninhibited flow of lubricating oil through the passageways 4.

The end of the plug remote from the end face 6 is formed with a recess 9 which, in use, receives and retains one end of the push rod of the engine. It will be seen from Figure 3 that the cylindrical outer surface 10 of the body projects beyond the recessed end of the slug such that the recess 9 is sited within the confines of the body 1.

Side holes 11 are formed in the outer surface of the body for the flow of oil to and from the passageways for lubrication purposes. The oil is recycled in a conventional manner.

In operation, the cam follower is positioned with its cam following surface in contact with a cam of a cam shaft of an internal combustion engine and with the lower end of the respective push rod seating within the recess 9. The arrangement is such that the cam follower is free to rotate about 3600 thereby spreading the wear experienced through its contacts with the camshaft cam and the push rod.

It will be appreciated that the foregoing is merely exemplary of a cam follower in accordance with the invention and that modifications can readily be made thereto without departing from the true scope of the invention.

Claims

CLAIMS:

1. A cam follower for an internal combustion engine, the cam follower comprising a body shaped at one end to define a cam following surface and recessed at its other end to receive and retain one end of a push rod, the body including through passageways for the flow of lubricant.

2. A cam follower as claimed in Claim 1 wherein its body is generally circular in cross-section with the cam following surface spaced forwardly of the main body portion and symmetrically about the longitudinal axis of the body.

3. A cam follower as claimed in Claim 1 or Claim 2 wherein the cam following surface is present on the forward end of an extension piece of the main body portion, the extension piece protruding from the central slug of the body with a waist interposed between the slug and the extension piece.

4. A cam follower as claimed in any one of Claims 1 to 3 wherein the passageways are aligned generally parallel to the longitudinal axis of the body in an array about the central slug of the body.

5. A cam follower as claimed in Claim 4 wherein eight passageways are symmetrically positioned about the slug of the body are provided.

6. A cam follower substantially as herein described and as described with reference to Figures 1 and 2 of the accompanying drawings.

6. A cam follower as claimed in any one of Claims 1 to 5 wherein the recess is formed in the end of the slug remote from the extension piece and the outer periphery of the body portion may extend beyond the end of the slug whereby the recess is positioned within the confines of the body.

7. A cam follower as claimed in any one of the preceding Claims wherein a series of holes is formed in the outer surface of the cam follower, these holes communicating with one or more of the lubricant flow passageways.

8. A generally cylindrical cam follower including a plurality of longitudinally extending lubricant flow passageways disposed about a central slug, the slug being formed at one end with a cam following surface end at its other end with a recess into which one end of a push rod can seat.

9. A cam follower substantially as herein described and as described with reference to Figures 1 and 2 of the accompanying drawings.

Amendments to the claims have been filed as follows CLAIMS:

1. A cam follower for an internal combustion engine, the cam follower comprising a body of generally circular cross section which is recessed at one end to receive and retain one end of a push rod, and an extension piece protruding from the other end of the body with a waist between the body and the extension piece, the extension piece including a cam following surface disposed symmetrically about the longitudinal axis of the body and the body including through passageways for the flow of lubricant.

2. A cam follower as claimed in Claim 1 wherein the passageways are aligned generally parallel to the longitudinal axis of the body.

3. A cam follower as claimed in Claim 2 wherein eight passageways are symmetrically positioned about the longitudinal axis of the body.

4. A cam follower as claimed in any one of the preceding Claims wherein a series of holes is formed in the outer surface of the cam follower, these holes communicating with one or more of the lubricant flow passageways.

5. A generally cylindrical cam follower including a plurality of longitudinally extending lubricant flow passageways disposed about a central slug, the slug being formed at one end with a cam following surface end at its other end with a recess into which one end of a push rod can seat.