US3002508A

US3002508A - Adjustable cam follower

Info

Publication number: US3002508A
Application number: US24071A
Authority: US
Inventors: Loren R Barker; Dwight W Parken; Donald C Kaiser
Original assignee: Caterpillar Tractor Co
Current assignee: Caterpillar Inc
Priority date: 1960-04-22
Filing date: 1960-04-22
Publication date: 1961-10-03
Anticipated expiration: 1978-10-03
Also published as: DE1196036B

Description

Oct. 3, 1961 L. R. BARKER ETAL 3,002,508 ADJUSTABLE cAM FoLLowER Filed April 22. 1960 INVENTORS URE/v R 5,49 DAV/@Hr W ,D B Y @0N/:Lp C ,4,

@WM5-'5, e y. ATToRNgYg United States ,Y Patent O M ors to Caterpillar Tractor Co. Peori Ill. of California a, Y, a corporation Filed Apr. 22, 1960, Ser. No. 24,071 Claims. (Cl. 12S-90) This invention relates to cam followers of the kind employed in an internal combustion engine such for example as those used between cams and valve stems where the cams are employed to open the valves against the force of springs which close them.

ITIhe clearance between the cams and followers is crrtrcal in an internal combustion engine if smooth, eilicrent and relatively quiet operation is to be obtained.`

It is the object of the present invention to lprovide means contained within a cam follower to vary clearance or adjust the effective length of the follower by simple turning movement which may be accomplished with a conventional tool. i A'further object of the invention is to provide means in such cam follower to preserve the clearance for which 1t is set by preventing accidental turning movement as the result of vibrations set up by engine operation.

Further and more specific objects and advantages of the invention are made apparent in the following specilication wherein it is described in detail by reference to the accompanying drawings.

The invention is disclosed herein as adapted to an engine having one or more overhead cam shafts with cams arranged in alignment with the axes of the valves though its adaptability to other environments will become apparent upon an understanding of its construction and operation.

In the drawings:

rFIG. l is a sectional view through a portion of the cylinder head of an internal combustion engine showmg a cam follower embodying the present invention in place therein between the cam and valve stem with which it is associated, the Section being taken on line r-I of FIG. 2;

FIG. 2 is a sectional view looking upwardly on the line II-II of FIG. l;

FIG. 3 is a fragmentary detail showing a modificatlion olf one part of the cam follower yillustrated in FIG.

FIG. 4 is a similar view illustrating another modification thereof.

Referring first to FIG. l of the drawings a portion of an engine head block is shown at as being bored for the sliding reception of an inverted cup-shaped cam follower 11 which engages a spring seat 12 secured to the upper end of a valve stem shown at 13. A cam shaft 14 disposed above the cam follower has a cam with a lobe 1S thereon which, upon rotation of the shaft, will engage the cam follower and depress it to open the valve at the opposite end of the stem 13 against the force of the spring 16 which normally holds the valve closed.

The structure so far described is, of course, dupli cated for each valve in the engine, the number of valves depending upon the number of cylinders in the engine as well as the number of valves employed per cylinder. The cam shaft 14 is rotated in a well-known manner by being geared to the crankshaft of the engine and the valves are the usual intake and exhaust valves which control communication with the combustion chamber of the engine.

In the cam follower of the present invention, contact between the follower and the spring seat at the end of 3,002,508 Patented Oct. 3, 1961 ICC the valve stem is made through a threaded post 18 disposed centrally of the interior of the follower so that upon rotation it will be advanced toward or away from `the valve stem. The threaded post 18 is provided with an annular flange with a serrated edge 20 disposed just above the upper surface of the spring seat 12 and the seat 12 has an annular concentric groove for the reception of the end of Va Phillips screwdriver as shown in broken lines at 23. The Phillips screwdriver is insertable through an angularly disposed bore 24 in the side wall of the cam follower which guides the screwdriver to a position where its fluted end meshes with the serrations 20 when its extreme end rests in the grove Z2. Consequently when the screwdriver is turned, its lluted end acts in the manner of a gear meshing with the serrations 20 to impart rotation to the post 18 and effects adjustment of the clearance between the top of the cam follower and the base circle of the cam. A proper clear.- ance is established by a feeler gauge as represented in dotted lines at 26 inserted between the cam and the -top of the follower. Thus, simply turning the screwdriver, which is positively guided to its proper position with relation to the parts with which it is used, effects adjustment of the effective length of the cam follower.

To prevent unintentional yturning of the threaded post 18 which might occur due to vibrations set up by operation of the engine, a plug 27 of nylon, Derlin or other similar relatively soft material is pressed against the threaded periphery of the post 18 as by means of a -set screw 28. This set screw may be of the countersunk or Allen head-type which can be advanced to press the plug 27 against the post 18 after the cam follower has been adjusted. To prevent loss of the set screw due to engine vibration, or even backing out of the screw to a position where it would interfere with reciprocation of the follower, the bore in which it is received is only partially tapped leaving a shoulder 29 adjacent its outer end. Tapping is accomplished from the opposite side of the cam follower through a bore shown at 30 in dotted lines, and the set Vscrew and plug are also inserted through this bore.

A modification of the means just described for preventing accidental rotation of the post 18 is shown in FIG. 3 wherein the plug 27 is urged against the post by a spring 32 held in place as by a Welsh plug 33. A still further modification is shown in FIG. 4 wherein the same plug 27 and the spring 32 are contained in a blind hole which is drilled from the opposite side of the head through the opening 30 shown in FIGS. l and 2.

We claim:

1. A cam follower of the kind described comprising a reciprocable cup-like member with an open end embracing a valve stem which has a spring seat adjacent its end, a closed end engageable by the lobe of a rotatable cam, a post threaded in the follower concentric and engageable with the valve stem, a flange on said post, aud means to facilitate engagement of said flange for rotating said post to vary the eilective length of the follower.

2. A cam follower of the kind described comprising a reciprocable cup-like member with an open end embracing a valve stem which has a spring seat adjacent its end, a closed end engageable by the lobe of a rotatable cam, a post threaded in the follower concentric and engageable with the valve stem, a flange on said post, said flange having a serrated edge, and said follower having an opening to guide a tool with a fluted end portion into engagement'with the serrated edge whereby rotation of the tool will rotate the post to vary the effective lengh of the follower.

3. A cam follower of the kind described comprising a reciprocable cup-like member with an open end embracing a valve stem which has a spring seat adjacent its end, a closed end engageable by the lobe of a rotatable cam, a post threaded in the follower concentric and engageable with the valve stern, a ange on said post, said ange having a serrated edge, and said follower having an opening to guide a tool with a fiuted end portion into engagement'with the serrated edge whereby rotation of the tool will rotate the post to vary the effective length of the follower, said ange being disposed adjacent to and concentric with the spring seat, and said spring seat having an annular groove to receive the end of said tool while it is operatively engaged with said serrated edge.

4. A cam follower of the kind described comprising a reciprocable cup-like member with an open end embracing a valve stem which has a spring seat adjacent its end, a closed end engageable by the lobe of a rotatable cam, a post threaded in the follower concentric and engageable with the valve stem, a flange on said post, means to facilitate engagement of said flange for rotating said post to vary the effective length of the follower, and means frictionally'engaging said post to prevent accidental rotation thereof.

5. A cam follower of the kind described comprising a reciproc-able cup-like member with an open end embracing a valve stem which has a spring seat adjacent its end, a closed end engageable by the lobe of a rotatable cam, a post threaded in the follower concentric and engageable with the valve stem, a flange on said post, means to facilitate engagementpf said ange for rotating said post to vary the effective length of the follower, and means frictionally engaging said post to prevent accidental rotation thereof, said last means comprising a plug of soft material engaging the threads on the post and means to urge it into Ifirm engagement with the threads.

ReferencesCited in the file of this patent UNITED STATES PATENTS 1,225,565 Birkigt May 8, 1917 1,363,398 Davids Dec. 28, 1920 1,443,715 Peraza Jan. 30, 1923 1,950,222 Buckley Mar. 6, 1934 1,987,239 Lochrane Jan. 8, 1935 2,188,859 Edwards Jan. 30, 1940 FOREIGN PATENTS 601,193 France Nov. 26, 1925