US3521608A - Self-contained hydraulic valve lifter - Google Patents

Description

July 28, 1970 E. w. SCHEIBE SELF-CONTAINED HYDRAULIC VALVE LIFTER Filed Oct. 16, 1968 Lll UYVENTUR. 57/05 ZZZ Jae/e M ATTORNEY United States Patent 3,521,608 SELF-CONTAIN ED HYDRAULIC VALVE LIFTER Elias W. Scheibe, Grand Rapids, Mich., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed Oct. 16, 1968, Ser. No. 768,008 Int. Cl. F011 1/24 US. Cl. 123-9057 Claims ABSTRACT OF THE DISCLOSURE An overhead cam and valve engine with a self-contained hydraulic valve lifter directly interposed between the cam and valve stem, the lifter including an inverted cup slidably guided in a bore surrounding the valve spring, a valve stem abutting member suspended for telescopic movement within the cup by a fluid impervious diaphragm, and a dished spring plate interposed between said member and the closed end of the cup, the spring plate serving both to take up lash between the cam and valve stem and to form the hydraulic pressure chamber of the lifter.

BACKGROUND OF THE INVENTION Field of the invention This invention relates to hydraulic valve lifters and the like for maintaining substantially zero lash in motion transmitting mechanisms such as, for example, cam operated valves of internal combustion engines, and particularly to hydraulic valve lifters of the self-contained type which directly interconnect the cam and valve stem of an overhead cam and valve engine. More specifically, my invention is directed to the use in such a lifter of a dished spring plate which serves the dual function of both taking up lash between lift strokes of the cam, and of defining one end wall of the pressure chamber in which hydraulic fluid is confined to transmit the valve opening load during the cam lift stroke. In the preferred embodiments illustrated, this dished spring plate is arranged within a slidably guided, inverted cup-shaped, outer member of the lifter, i.e. between the cam-abutting closed upper end of the outer member and a valve abutting inner member which is telescopically movable within the outer member. Such dished spring plate also may serve to partition the fluid pressure chamber from the fluid reservoir chamber, wherein fluid is retained by a flexible diaphragm sealingly interconnecting the inner and outer members together. Various arrangements of passage means may be provided to interconnect the two chambers, for both relatively unrestricted flow to the pressure chamber when the load is relieved, and restricted flow therefrom to the reservoir chamber when load is applied during the cam lift stroke.

Description of the prior art Locating a hydraulic valve lifter for direct actuation of the valve from an overhead cam is broadly old, as shown, for example, in the US. Pat. No. 3,286,702 to Dadd. Also, self-contained type hydraulic valve lifters wherein the fluid reservoir chamber is sealed by a flexible diaphragm are old, as shown, for example, in US. Pat. No. 2,203,952 to Eshbau-gh. Further, dished spring plates have been previously employed as lash take-up devices both in hydraulic valve lifters as well as in valve silencers, as shown by the US. Pats. Nos. 2,074,155 to Truesdell, 2,468,332 to Johnson and 1,100,912 to Rich. In none of these prior patents nor other known prior constructions, however, is a dished spring plate used in the manner referred to above.

3,521,608 Patented July 28, 1970 SUMMARY OF THE INVENTION One of the most important advantages of my invention is that the dished spring plate enables obtaining a very close spacing of the cam from the valve or other member to be driven by the cam. This is desirable in the interests of compactness and low profile of an automotive vehicle engine of such cam-over-valve design. Also of considerable advantage is the fact that the valve lifter weight is greatly reduced, both by elimination of the usual slidingrfit plunger and by the fact that the close coupling of the thrust transmitting parts enables the side walls of the outer cup-shaped member to be made thinner since the side thrust forces thereon are much reduced. Weight reduction is important, not only in material economy but in reducing inertia forces which interfere with valve motion control during high speed cam action. A third major advantage realized by my invention is that manufacturing cost, as well as likelihood of litter malfunction in service, are greatly reduced by eliminating the need for close-tolerance fits between the parts of the lifter.

BRIEF DESCRIPTION OF THE DRAWING These and other advantages and objects of the invention will be apparent from the following description having reference to the drawing showing two alternative specific embodiments wherein:

FIG. 1 is a transverse sectional view through a portion of an internal combustion engine of the overhead cam and valve type showing my invention embodied in a. lifter interposed directly between the cam and valve stem.

FIG. 2 is an enlarged longitudinal sectional View through the lifter, showing its internal parts in detail.

FIG. 3 is a sectional view similar to FIG. 2 but showing a modified construction.

FIG. 4 is a fragmentary sectional view similar to FIGS. 2 and 3 but showing a further modification.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now in detail to the drawings, in FIG. 1 the engine illustrated includes a cylinder block 1 with a piston 2 fitted in a cylinder bore 3. Suitably secured to the top of the block is a cylinder head 4 having a valve port 5 whose communication with the cylinder bore 3 is controlled by a poppet valve 6 having its stem 7 slid ably guided for reciprocation in a valve bore 8. Mounted directly opposite and above the upper end of the valve stem 7 is a rotary cam 9 which is journaled in a separate housing portion 10 of the head 4, the cam being suitably driven by means not shown to effect downward movement of the valve against its return spring 11. A cover 12 is secured to the housing portion 10 for enclosing the cam 9.

Directly interposed betweenthe upper end of the valve stem and the cam 9 is a hydraulic valve lifter, designated generally by the numeral 13, which comprises an inverted cup-shaped outer member 14 slidably guided in a lifter bore 15 embracing the upper end of the valve stem and its return spring 11. As shown in FIG. 2, an inner member 16 is arranged for telescopic movement within the outer member 14 for abutment with the upper end of the valve stem 7. This member 16 is spaced from the outer members closed end 17 which abuts the cam 9 (FIG. 1), and interposed between such closed end 17 and the inner member is a dished spring plate 18. The spring plate, as shown, has its convex side facing the valve stem abuttable member 16 and its concave side facing the end wall 17 of the outer member. Between the spring plate and this end wall there is thus provided a hydraulic pressure chamber 19 which is filled with fluid such as oil. The underside of the end wall 17 may be annularly grooved as indicated at 20 to increase its volume, and passage means is provided which connects the pressure chamber 19 with the opposite or convex side of the spring plate. This passage means as shown in FIG. 2 includes a central aperture 21 in the spring plate and a smaller opening or orifice 22 therein which is located laterally intermediate the outer periphery 23 of the spring plate and the inner member 16. Within the pressure chamber 19 is shown a check valve in the form of a ball 24 which is operative to close the relatively large central opening 21 in response to fluid pressure in the chamber 19 exceeding that on the convex side of the spring plate. A recess 25 in the end wall 17 provides clearance for upward opening movement of the ball 24, as well as loosely retaining it in position for reclosing the spring plate opening 21. The upper surface of the inner member 16 is shown provided with a groove or slot 26 for insuring unrestricted flow of the hydraulic fluid into the pressure chamber 19 through the opening 21 when the ball is free to uncover the opening 21, as when the fluid pressure below the spring plate exceeds that in the chamber 19.

While the inner member 16 could be arranged to be slidably fitted to the side walls 27 of the outer member and make up oil introduced between the inner member 16 and the spring plate 18 through side porting of the outer member, it is preferred in accordance with FIG. 2 that the lifter be of the self-contained type. A fluid impervious diaphragm 28 of resilient flexible material such as oil resistant rubber is therefore provided to both suspend the inner member 16 for telescopic movement within the outer member and to provide a fluid reservoir chamber 29 below the spring plate. This diaphragm, of annular shape, has its inner extremities sealingly em bracing the inner member 16, and the outer extremities of the diaphragm are sealingly secured to the side walls of the outer member by a retainer ring 31 press fitted into the latter.

In operation of this FIG. 2 embodiment of the invention, rotation of the cam 9 on the opening or lift stroke of the poppet valve 6 causes the outer member 14 of the lifter to move downwardly. Such movement, being opposed by the engine valve spring 11, results in the lifter inner member 16 applying an upward force against the convex side of the spring plate 18 which tends to deflect it and reduce the volume of the pressure chamber 19. The resulting higher pressure of the oil therein forces the ball check valve 24 to its closed position, blocking the opening 21 in the spring plate, and this trapped oil thereafter acts to transmit the downward movement of the outer member to the lifter inner member 16 and the engine valve stem 7. Some foreshortening of the lifter is desired during each such lift stroke in order to insure that the engine valve 6 will fully close on the return stroke. A small amount of leakage from the chamber 19 is accordingly intended to occur around the outer extremities 23 of the spring plate, coupled with additional restricted flow of such oil through the orifice 22, into the reservoir chamber 29 during each lift stroke. The size of the orifice 22, as well as the possibility of its elimination entirely, is dependent upon the amount of such leakage as will occur around the outer extremities 23 of the spring plate. The latter leakage may, in turn, be controlled to some extent by either roughening or smoothing, as desired, the surfaces of co-abutment between the end wall 17 and the outer extremities 23 of the spring plate. Enlargement of the reservoir chamber 29 by the volume of this leakdown oil is accommodated by flexible diaphragm 28.

On the return stroke of the engine valve, as induced by the valve spring 11, the lifter moves upwardly with continued rotation of the cam until the engine valve 6 again reaches its fully closed position shown in FIG. 1. Thereafter, by reason of the aforementioned leakdown of oil from pressure chamber 19 during the preceding lift stroke, and the biasing action of the spring plate in maintaining abutment of the lifter inner member 16 with the valve stem and abutment of the lifter outer member 14 with the cam, the lifter will continue moving upwardly until the end wall 17 of the outer member again engages the no-lift or dwell portion of the cam. Some expansion or enlargement of the chamber 19 will therefore occur, causing the fluid pressure thereinto drop below that in the reservoir chamber 29. This fluid pressure diffrence enables the ball check valve 24 to uncover the spring plate opening 21 and oil to flow through the latter from the reservoir chamber to replenish that which had previously leaked out of the pressure chamber on the lift stroke. Also, such minute wear as may occur on the surfaces of the cam, lifter end wall 17, inner member 16 and the engine valve 7 to require a compensating increase in the effective operating length of the lifter is taken care of by additional flow of oil into the pressure chamber 19 via the opening 21 from the reservoir chamber 29.

Similarly, any foreshortening of the effective length of the lifter during engine warm up, as the result of thermal expansion of the valve stem 7 relative to the height of the cam, is compensated for between lift strokes by a lesser degree of filling of the pressure chamber from the reservoir chamber.

In the modified form of lifter shown in FIG. 3, the parts are arranged generally similarly to that of FIG. 2 but differ in the manner of providing for the relatively restricted and unrestricted rates of oil flow between the reservoir chamber and the pressure chamber. The outer member 50 of the lifter, as in the previous embodiment, has its end wall 51 facing the concave side of a dished spring plate 52, and the latter is provided with a central opening 53. No ball check valve is included in this lifter, however, nor is there any provision for leakdown oil to escape from the pressure chamber 54 to the reservoir chamber 55 via the outer periphery of the spring plate. Instead, all such transfer of fluid must occur through the central spring plate opening 53. To accomplish this, the inner member 56 has its upper surface 57 shaped as a portion of a cylinder so that when it is in abutment with the spring plate the circular opening 53 in the latter is uncompletely closed. This arrangement provides a restricted passageway 58 at each side of the circular opening 53 for leakdown of the oil from the pressure chamber during the valve lift stroke. Unrestricted flow through the opening 53 from the reservoir chamber to the pressure chamber, during the lifter recovery immediately following each reclosing of the engine valve, is effected by the inner member '56 moving a slight distance downwardly and away from the spring plate to additionally uncover the opening 53. This downward movement of the inner member is assisted by the action of a light coil compression spring 59 interposed between the spring plate and the inner member. Thus, as the engine valve closes and the lifter end wall 51 is in abutment with the base circle of the cam 9, the part cylindrical portion 58 of the inner member is momentarily spaced a slight distance from the spring plate, which spacing is taken up before the start of the next cam lift stroke. Also, in this embodiment, since it is desired to eliminate any leakdown of oil around the periphery of the spring plate during the lift stroke, the spring plate is provided with a downturned flange 60 at its outer periphery, which flange is sealingly embraced by the outer periphery member 61 of the diaphragm 62. The operation is otherwise as described with reference to the embodiment shown in FIG. 2.

In the further modification illustrated in FIG. 4 the spring plate has an enlarged central opening 71, through which extends a reduced upper end portion 72 of the inner member 73. Thrust forces between the latter and the spring plate are taken by a shoulder 74 surrounding the reduced portion 72, and this portion has its upper surface 75 part-cylindrically shaped in the manner of surface 57 of FIG. 3. Connecting transverse and axial passages 76, 77 are provided in the inner member 73 for oil flow between the pressure chamber 78 and the reservoir chamber 79, and a flat plate valve '80 loosely retained in a recess 81 in the end wall 82 of the lifter outer member 83 cooperates with the part-cylindrical surface 75 to provide the same relatively restricted and unrestricted flow control of oil as described with reference to the FIG. 3 embodiment. This FIG. 4 arrangement has the advantage such valve action is unaffected by wear between the spring plate and the inner member in operation.

It will be appreciated that, if desired, a restricted orifice such as shown at 22 in FIG. 2 may also be provided in the spring plate 52 of the FIG. 3 embodiment, as Well as in the spring plate 70 of the FIG. 4 embodiment. Likewise in the FIG. 2 embodiment, the outer periphery 23 of the spring plate 18 may be sealingly secured to the diaphragm 28 if it is desired to limit leakdown flow solely to the orifice 22. Also by using a diaphragm 62 of sufiicient stiffness and having the proper initial configuration to exert a downward biasing force on the inner member 56 the light coil spring 59 in the FIG. 3 embodiment may be dispensed with. Further, by rearrangement of the parts, the spring plates 18, 52 and 70 may have their convex sides facing the end wall of the lifter outer member instead of facing the inner member thereof. Various other changes in the parts and their arrangement will readily suggest themselves to those skilled in the art without departing from the spirit and scope of the invention as defined in the following claims.

I claim:

1. A hydraulic valve lifter including a generally cupshaped outer member having slidably guidable side walls closed at one end by an end Wall, an inner member extending into the outer member from the opposite end and telescopically movable therein, a dished spring plate interposed in axial thrust transmitting relation. between the inner member and said end wall and having its concave side cooperating with one thereof in defining a fluid pressure chamber, and passage means interconnecting said chamber and the convex side of the spring plate, said passage means including a restriction, whereby fluid pressure within said chamber assists the spring plate in transmission of thrust from the inner member to said end wall.

2. The invention of claim 1, including sealing means interconnecting said members against leakage of fluid therebetween and defining a fluid reservoir chamber on the convex side of the spring plate.

3. The invention of claim 2 wherein said sealing means has an annular portion sealingly embracing the outer periphery of the spring plate.

4. The invention of claim 1, wherein the spring plate has its concave side facing said end wall.

5. The invention of claim 4, wherein said passage means includes an aperture in the spring plate opposite the inner member, said inner member having an end face abuttable with the convex side of the spring plate and adapted to substantially but incompletely close said aperture when in abutment therewith.

6. The invention of claim '5, including a flexible annular diaphragm sealingly embracing the inner member and having its outer periphery sealingly secured to the outer member, said diaphragm cooperating with the inner member and spring plate in defining a fluid reservoir chamber connected to the pressure chamber via said passage means.

7. The invention of claim 1, wherein said passage means includes an aperture in the spring plate, and including a check valve in the pressure chamber operative to close said aperture in response to fluid pressure in said chamber exceeding that on the opposite side of the spring plate.

-8. The invention of claim 1, wherei nsaid passage means restriction is in the form of a small orifice in the spring plate, located laterally intermediate the outer periphery of the spring plate and the inner member.

9. The invention of claim 5, including spring means normally biasing the inner member out of abutment with the spring plate but yieldable to accommodate said abut ment under thrust loads applied to the inner member in operation.

10. The invention of claim 4, wherein said spring plate has an opening, said inner member has an upper portion extending into said pressure chamber through said opening, said passage means includes an axial Passage in said portion and a connecting transverse passage in said inner member below said upper portion, said portion having a part-cylindrical surface surrounding said axial passage, and a flat valve in the pressure chamber movable into abutment with said part-cylindrical surface to effect said restriction.

References Cited UNITED STATES PATENTS 2,109,815 3/1938 Best 123-90 2,187,008 1/ 1940 Baxter 123-90 2,526,593 10/1950 Voorhies 123-90 2,907,310 10/1959' Gleeson et al. 123-90 2,915,051 12/1959 Allen 123-90 2,971,502 2/1961 Wride 123-90 FOREIGN PATENTS 443,401 2/ 1936 Great Britain. 562,101 6/ 1944 Great Britain.

AL LAWRENCE SMITH, Primary Examiner U.S. Cl. XzR. 123-9058

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