US2404032A - Valve tappet mounting - Google Patents

Description

July 16, 1946. G. E. BURKS VALVE TAPPET- MOUNTING Filed July 9, 1945 5 Sheets-Sheet 1 IN VEN TOR.

George E. Burks BY aw y 7 W mH H ATTORNEY.

July 6, 1946. s. E. BURKS VALVE TAPPET -MOUNTING Filed July 9, 1945 3 Sheets-Sheet 2 m T m m George E. Bur-ks ATTTORAE).

July 16, 1946.

' a. E. BURKS VALVE TAPPET mopn'rme 3 Shets-Sheet 3 Filed July 9, 1945 mm MN QN em MN \N Q MN m m4 vQM NJIY \N |HP ii mm F. 3.

INVENTOR. George E. Burks ATTORNEY.

Patented July 16, 1946 VALVE TAPPET MOUNTING George E.

pillar Tractor 00.,

poration of California Application July 9, 1945, Serial No. 603,799

'1 Claims. 1

The present invention relates to the mounting of valve tappets or guides for valve tappets which are employed as a part of the valve operating mechanism of an internal combustion engine.

Conventional types of internal combustion engines comprise cylinders usually disposed vertically in a cylinder block. Valves which control the intake of air and the exhaust of residual products of combustion from the cylinders are actuated by mechanism which include push rods and tappets arranged vertically adjacent the cylinder block. The lower ends of the tappets are enaged by cams on the cam shaft disposed longitudinally of the block and driven in timed relation to the reciprocal action of the pistons in the cylinders. It is desirable that the cams engage squarely against the pets as the timing and the valves are critical factors in perfect engine performance. If the tappet guides are misaligned, the tappets do not seat squarely against the cams but may ride on one edge of the cam face. As a result of such operation, excessive wear takes place between the cam and shaft which affects the timing and opening of the valves. The tappet guide also becomes worn because of such misalignment and various other undesirable results occur.

It has been common practice to mount valve tappet guides against the side of the engine block on a flat surface and to secure them in place by cap screws. This practice required many machining operations, such as the production of a flat surface on the block and on the bracket, boring the tappet guide through the brackets and providing for the cap screws which extended through the 'bracket and into the block. Each of these operations had to be separately performed with no particular relation to the others or to the line of the cam shaft bearings in 'the block. Even allowing a minimum'tolerance prac-,

tical for machining operations of this kind, slight errors in each operation would sometimes accumulate to produce a substantial misalignment.

It is an object of the present invention to'over-. come the disadvantages herein referred to and to provide a mounting for valve tappets which insures perfect alignment of the tappets with relation to the cam shaft of the engine upon which they are mounted. A further object of the invention is to provide a means for mounting valve tappets which requires a. minimum of simple machining operations capable of being performed in a manner greatly to reduce thepossibilities of error:

Burks, Peoria, 111., assignor to Cater- San Leandro, Calif., a cor- 2 jects and advantages of the invention are made apparent in the following specification wherein reference is made to the accompanying drawings which illustrate a preferred form of the invenlower ends of the tapdistance of opening of Further and more specific obtation in spaced tion applied to an internal combustion engine of conventional design.

In the drawings:

Fig. 1 is a. diagrammatic view in side elevation of an internal combustion engin with portions broken away and illustrated in section to show the application thereto of valve tappet mount; ings embodying the present invention;

Fig. 2 is a. front elevation of the engine shown in Fig. 1 with a portion illustrated in section to disclose details of construction of the invention:

Fig. 3 is an enlarged view taken on the line III-III of Fig. 2;

Fig. 4 is a sectional view taken on the line IVIV of Fig. 3; and

Fig. 5 is a sectional view taken on the line V-V of Fig. 3.

The general arrangement of valve operating mechanism in a typicalinternal combustion engine is illustrated in Figs. 1 and 2 wherein the engine is illustrated at I0. Conventional cylinders, shown in dotted lines at Ii in Fig. 2, are disposed within the engine block and pistons l2 reciprocate in the cylinders and impart rotation to a crank shaft I! by means of connecting rods H. The upper ends of the cylinders are provided with intake and exhaust valves such as indicated at i5 and these valves have stems l6 engaged by rocker arms ll which are pivotally mounted as at l8. Springs, not shown, normally hold the valves IS in closed positions andthey are opened in timed succession, and in proper relation to the reciprocal action of the pistons in the cylinders, by means of pusher rods 19 disposed on the outside-of the -cylinder"iblock and engaging at their upper ends with the rocker arms l1 and at their lowerends with'tappets 20. The tappets 20 are mounted for. reciprocation in guides 2i and have lower e'nds projecting downwardly from said desand engageable with cams 22 on a cam shaft '23. The cam shaft 23 is journaled for-r0- bearings 24 which, as illustrated in Fig. l,.are cast as integral parts of the engine block. The cam shaft is connected with the crank shaft I3 for rotation thereby by means of a train of gears, not shown, in accordance with conventional practice. By reason of this connectlon. the cam shaft is rotated in timed relation to the crank shaft and to the reciprocal action of the pistons which drive the crank shaft. The arrangement of the individual cams'22 on fragmentary sectional machined to present J the cam shaft is such that during each rotation of the shaft, each one of the intake and exhaust valves II is opened in properly timed relationship to the operation of its respective piston,

The engine illustrated in Fig. l is of the six cylinder type and each cylinder has an associated pair of valves, push rods l9, tappets 29 and tappet guides 2|. The pairs of tappet guides 2| are illustrated herein as connected in groups of three pairs each so that two such groups are employed to accommodate six cylinders. It is, of course, to

- be understood that the invention herein described is applicable to engines having any number of cylinders and that the grouping of the tappet guides may be varied from the arrangement herein illustrated.

In conventional construction, the tappet guides 2| have been formed as a part of a casting having a flat surface which flat surface is bolted flush against a flat-surface on the engine block for support. Such construction has been conducive to misalignment of the guides through error in laying out and machining operations so that in some cases the lower ends of the tappets have not rested squarely on the surfaces of the cams 22 but rather have been anguiarly disposed so that they engaged one edge only of the cams with the result that excessive wear and imperfect engine operation follows.

According to the present invention, the tap- Det guides 2| are formed as a part of a casting or castings which are secured to the engine block in a manner which practically eliminates possibility of their misalignment. For example, as shown in Figs. 1 and 3, the tappet guides 2| areformed in groups of three pairs integrally cast and connected by semi-cylindrical connecting members 25 which have centrally disposed reinforcing ribs 28. The exact shape of the connecting members 28 and ribs 26 is subject to variation and is not an essential characteristic of the mounting structure so long as it forms a rigid connection between the pairs of guides 2|. Between the guides 2| of each pair a similar but shorter connecting shape is employed and is provided with an enlarged semi-cylindrical portion 21, see also Figs. 4 and 5, capable of being a perfect semi-cylindrical contour. This surface 21 is adapted to be disposed against a registering semi-cylindrical surface 28 machined on the side of the engine block, as best illustrated in Fig. 2, where the block is shown as cast to a shape providing surfaces for such machining. Cap screws 29 are employed to secure the castings against the side of the block with the semi-cylindrical machined surfaces 21 seating against the complementary concave surfaces 28 formed in the side of the block. With this construction a relatively small number of cap screws is needed as the complementary semicylindrical surfaces provide an accurate seat which holds the casting in alignment and the cap screws are necessary only to prevent the casting from moving away from the block.

The construction herein described lends itself to simple and easily performed machining operations which insure accuracy in the alignment of the tappet guides. For example, the semicylindrical concave seats 28 in the side of the block may be bored at the same time that the block is set up for machining the crank shaft bearing brackets and the bearings 24 for the iongitudinally extending cam shaft 23. This insures-thatfall offfthe seats 28 will be perfectly aligned with the crank's'hsit so that if the complementary seating surfaces 21 on the casting are true with relation to the vertical bores in the tappet guides 2|, the lower ends of the tappets must rest squarely on the surfaces of the cams 22. The semi-cylindrical surfaces 21 on the casting which includes the tappet guides 2| are somewhat larger than the rest of the casting and are spaced between the longer portions which form the guides 2|. Hence, the entire casting may be supported between centers on a lathe or similar machine for formation of true surfaces on the members 21 and the same centers established at the ends of the casting for forming these surfaces may be used in aligning the work for boring out the guides 2| for reception of the reciprocal tappets 20. Consequently, the bores of the tappet guides can readily be formed normal to the longitudinal axis about which the surfaces 27 are turned and as the seats 2| in the engine block which receive the surfaces 21 are formed parallel to the cam shaft bearings, a perfect seating of the tappets against the surfaces of the cams on the cam shaft is assured. The alignment of the tapped holes for the cap screws 29 is easily accomplished and does not affect the position of the bracket which the cap screws support. a

I claim:

1. A device for mounting valve tappets or the like on the side of an engine block which comprises a casting having portions of cylindrical contour formed thereon and adapted to be received in recesses of complementary contour in the block.

2. A device for mounting valve tappets or the like on the side of an engine block comprising a casting having tappet guides bored therein, semi-cylindrical seat portions on the casting formed about an axis at right angles to the axes of said tappet guides and adapted to seat in recesses of complementary contour in the block.

3. Adevice for mounting valve tappets on an engine block for engagement with spaced cams on an engine cam shaft which comprises, a bracket, tappet guides bored in the bracket, and 9. cylindrical surface on the bracket formed on an axis at right angles to the axes of said tappet guides, whereby the cylindrical surface will seat in a cylindrical recess bored in the block parallel to the cam shaft to position the tappets at right angles to the cam shaft.

4. A device for mounting valve tappets on an engine block for engagement with spaced cams on an engine cam shaft which comprises, a bracket, tappet guides cylindrical surfac on the bracketformed on an axis at right angles to the axes of said tappet guides, whereby the cylindrical surface will seat in a cylindrical recess bored in the block parallel to-the cam shaft to position the tappets at right angles to the cam shaft and means to secure the bracket against the engine block.

5. A device for mounting valve taDDets on an engine block comprising, a plurality of tappet guides formed integrally with connecting and supporting members, and a plurality of aligned conve'x seating portions on said connecting and supporting members adapted to register with complementary concave seats formed on the engine block.

6. A device for mounting valve tappets onan engine block comprising, a guides formed integrally with connecting and bored in the bracket, and a plurality of tappet and a plurality of aligned convex seating portions on said connecting and zgoeose nesting members, aligned convex seating portions on said connecting members having semi-cy1indricalosurfaces formed on a common center line and adapted to register with complementary 5 concave seats formed in the engine block.

GEORGE E. BURKS.

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