US2634714A

US2634714A - Hydraulic valve lifter

Info

Publication number: US2634714A
Application number: US231986A
Authority: US
Inventors: Glenn T Randol
Original assignee: Individual
Current assignee: Individual
Priority date: 1951-06-16
Filing date: 1951-06-16
Publication date: 1953-04-14
Anticipated expiration: 1970-04-14

Description

A ril'14,' 1953 1-, RA QL 2,634,714

HYDRAULIC VALVE LIFTER Filed June 16, 1951 agl n I J fi A INVENTOR.

Patented Apr. 14, 1953 UNITED STATES PATENT OFFICE HYDRAULIC VALVE LIFTER 7 Glenn '1'. Randol, Mountain Lake Park, Md. Application June 15, 1951, Serial No. 231,986

17 Claims. 1

The present invention relates to valve lifters adapted to maintain automatically zero clearance in the valve drive train of an internal-combustion engine. The invention particularly relates to hydraulic valve lifters of improved operation and construction.

- Valve lifters of the mechanical type presently used commercially do not provide for automatic adjustment of the valve drive train, nor for automatic elimination of backlash in the valve operating mechanism of an internal-combustion engine. In mechanical drive trains, clearance is provided between the rocker arms of the drive train and the stems of the valves. As the engine is operated, the clearance is increased due to the impact and wear to which the train is subjected. Increased clearance between the rocker arms and valve stems results in inemcient and noisy operation of the engine and requires a partial disassembly of the engine to adjust the tappets; that is, to temporarily correct the clearance between the rocker arms and Valve stems by eflecting a manual adjustment in the drive train.

To avoid the necessity of frequent tappet adjustment and to eliminate noisy and inefficient operation of the engine, some commercial engines are equipped with hydraulic valve lifters which attempt to effect automatic adjustment of the valve drive train to maintain zero clearance in the train, so that in effect, the train functions as a solid body in opening the valves in the engine.

The object of the present invention is to provide an improved valve lifter mechanism capable of constantly and consistently maintaining zero clearance and effectively eliminating backlash in the valve drive train of an internal-combustion engine.

Another object of the invention is to provide an improved hydraulic valve lifter particularly adapted for use with a conventional valve operating cam, which lifter is of optimum design for maintaining silence of operation and affording long life for the cam itself and the mechanism operated thereby. A further object of the invention is to provide an improved hydraulic valve lifter assembly that may be readily substituted for any and all valve lifter mechanisms presently used commercially, whether mechanical or hydraulic.

A still further object of the invention is to provide an improved hydraulic valve lifter that is economical of manufacture, compact, readily assembled and disassembled, substantially uniformly actuated into and out of engagement regardless of the relative disposition of the mem-- bers thereof, and effective to compensate for any relative movement between the members of the valve lifter mechanism.

In accomplishing the objects of the present invention, I provide a valve lifter mechanism having some similarity to commercial hydraulic valve lifters and including substantially all of the elements or members of commercial hydraulic valve lifters. In particular, the valve lifter mechanism of the present invention comprises a pair of relatively movable body members defining a fluid pressure chamber therebetween, passage means, including a port in one body member, for conducting fluid under pressure to the chamber, and a check valve positioned within the chamber and adapted to close the port in the one body member to close the pressure chamber. The fluid in the chamber is substantially incompressible and as a result the fluid prevents relative movement between the body members in one direction When the check valve is closed. The body members are, in effect, locked together for conjoint movement to open the engine valve. While some reliance is placed upon the hydraulic impact principle utilized in commercial hydraulic valve lifters to hold the check valve in closed position, the present invention provides improved mechanism operable by hydraulic force of a less sudden impact and smaller magnitude than that required for operation of commercial hydraulic valve lifters. The improved mechanism is in the nature of a piston operating in a cylinder and operatively associated with the check valve to move and/or to hold the valve in closed position. The cylinder means of the present invention surrounds the port in the one body member so that fluid from the engine lubricating system flows through the cylinder. The piston is provided with one or more orifices through which the fluid flows to the chamber defined between the two body members. The one side of the piston is exposed to the fluid in the chamber and the orifices therein form passageways for the flow of fluid. In the preferred embodiment of the invention, a substantial area of the piston head is exposed to the fluid in the chamber and the orifices in the piston are small to form restricted passageways so that the piston is very sensitive to changes in fluid pressure within the chamber. However, the exposed area of the piston and the size and/or number of the orifices therein may be varied so as to vary the sensitivity of piston reaction from zero to optimum response. Upon movement being imparted to one of the body members, the fluid in the chamber between the body members is subjected to an increase in pressure. The piston, if the same is designed for reaction to pressure change, being exposed to the fluid in the chamber, is moved upon increase in pressure in the chamber to move and/or to hold the check valve to its seat and thus to effectively lock the two body members together for conjoint movement in opening the engine valve. Even with a conventional cam, the increase in pressure in the chamber between the two body members is of sufficient suddenness to effect movement of the piston before any measurable quantity of fluid can be forced from the chamber through the apertures in the piston to the opposite side thereof to balance the pressures on the piston. Therefore, the check valve is moved to and/or held on its seat in a substantially positive manner, without detrimental flow of fluid past the check valve, to effectively lock the body members together for conjoint movement without loss of the zero-lash condition established while the one body member was riding the base circle of the engine cam. Due to movement of the piston in the cylinder, the fluid between the piston and the valve will be subjected to an increase in pressure and will act upon the valve to assist in retaining the valve on its seat. The valve of the present invention is not supported in static fluid.

In one embodiment of the invention, the piston is operatively associated with the check valve by means of a spring. In this embodiment, the check valve is preferably delicately balanced between two springs engaging opposite sides thereof. The springs may substantially negative the effect of each other, or one may be stronger than the other to bias the valve in a predetermined direction. In one case, the spring urging the check valve away from its seat is preferably slightly stronger than the spring confined between the valve and the piston so as normally to maintain the valve in open position when the one body member of the lifter mechanism is riding the base circle of the engine cam. In this case, the lower spring serves to counterbalance the weight of the ball so that weight is not a governing factor in moving the ball to its seat. In another case, the lower spring may serve normally to bias the valve to its cooperating seat, preferably lightly. In the latter case, the piston may be so designed, with respect to the area thereof exposed to the fluid in the chamber and the size and number of orifices therein, as to vary piston sensitivity from zero to optimum, whereas in the said one case, the piston must have some sensitivity to pressure change to move the valve to its seat. In the said latter case, the piston, at zero sensitivity would serve as a fixed seat for the lower spring which would act .to seat the valve and to maintain the valve seated, even against the bias of the upper spring if the same were provided, which would not be entirely essential in this latter case.

In another embodiment of the invention, the check valve is normally open and the piston is ,operatively associated with the check valve by means of a pedestal or stem secured to the piston. The check valve may merely be supported by the pedestal or may be formed integrally therewith. In this embodiment, the piston is preferably designed for optimum sensitivity.

In both embodiments of the invention, means are provided for maintaining the ball check valve in substantial alignment or registry with its seat.

Other objects and advantages of the present invention will become apparent from the following detailed description of preferred embodiments of the invention, wherein reference is made to the accompanying drawings, in which:

Figure l is a fragmentary vertical sectional view through an internal-combustion engine, showing a valve lifter mechanism constructed in accordance with the principles of the present invention in a valve drive train of the engine, and showing the valve lifter mechanism in engine valve closed position;

Figure 2 is an enlarged transverse sectional view taken substantially along the line 11-11 of Figure 1, looking in the direction indicated by the arrows;

Figure 3 is an enlarged transverse sectional view taken substantially along the line IIIIII of Figure 1 looking in the direction indicated by the arrows;

Figure 4 is a partial vertical sectional view, on an enlarged scale, of the valve lifter mechanism shown in Figures 1 to 3, showing the mechanism in operated position; and

Figure 5 is a partial vertical sectional view, similar to Figure 4, of a modified embodiment of the present invention, showing the mechanism in engine valve closed position.

Referring now to the drawings, and particularly to Figure l, I have shown a preferredembodiment of my invention incorporated with a. conventional internal-combustion engine I0 having a plurality of valves, one of which is shown at H. A valve drive train indicated generally at 12 is provided, as is well understood, for each valve of the engine, and the valve drive train is conventional in all respects except for the valve lifter mechanism l3 of the present invention, which is embodied therein. The valve drive train l2, as shown, extends between the valve II and the cam shaft M of the engine. The valve Il may be of any known construction and the valve selected for illustration includes a stem portion I6, guided in a collar part l1, and having spring means [8 associated therewith for normally tending to close the valve. A rocker arm I9, pivotally mounted intermediate its ends on the oil distributing pipe 20, is adapted to bear at one end 2| thereof against the free end of stem l6 when rotated in a clockwise direction as viewed in Figure 1 of the drawings, to open valve II against the force of the spring means IS. The other end 22 of the rocker arm [9 has a fitting 23 secured therein, and with which is associated a connector member '24 having one end of a hollow push rod 25 secured thereto. The other end of push rod 25 has a connector 25 secured thereto, which bears against the dished upper end portion of an inner body member, indicated generally at 21, which is mounted, in the embodiment of the present invention herein disclosed, for vertical sliding movement in a bore 28 of an outer body part 29. The inner body part 21 and the outer body part 29, as will presently appear, form a part of the lifter mechanism [3 of the present invention. The end portion 22 of the rocker arm l9, fitting 23, connector 24 and member 26 are provided with suitable bores, and, together with the hollow rod 25, conduct oil under pressure from the pipe 20 of the pressure lubricating system of the engine to a bore 30, formed centrally of the inner body part 2-1, and thence to a chamber or reservoir 3| provided in the inner body member 21, to a bore 32 at the lower end of the inner body member '21, and thence to a chamber, indicated generally at 33 defined between the lower end of the inner body member 21 and the lower end of the bore 28 or inner end wall of the outer body member 23. The. function and purpose of the chamber 33 will be referred to in greater detail hereinafter.

The lifter mechanism I3 of the present invention comprises the outer body part 29, the inner bod part 21 mounted for rectilinear sliding movement and free rotational movement in the bore 28 of the outer body member 28, spring means 34 confined between the inner body member 21 and the outer body member 25 tending to separate but accommodating relative movement in either direction between the two, a cage 35 for receiving a ball check valve 33, a ball actuating piston 31, a tube 38 defining a cylinder within which the piston 31 is slidably received, resilient means in the form of a spring 39 between the inner body member 21 and the ball 33 and resilient means in the form of a spring 43 between the ball 38 and the piston 31. The outer body member 29, adjacent the upper end thereof, is formed with an annular groove 4! for receiving a snap ring 42 which serves to retain the inner and outer body members in assembled relation when the valve lifter mechanism 43 is removed from the block of the engine.

The inner body member 21 comprises a body member 43 having an enlarged axial bore forming the reservoir 3| and terminating at its lower end in a valve seat 44, formed by a conical counterbore in the bore 32. The body member 43 is closed at its upper end by a plug 45, which is preferably threaded into the open end of the body member 43. The-threaded connection between the plug 45 and the body member 43 has been indicated as being preferable, but it is apparent that the plug 45 could be press-fitted into the body member 43, or the body member and the plug could be united in any usual manner to provide the reservoir 3 I. The plug 45 is dished at its upper end to receive the connector 25 and is provided with the bore 30 establishing communication between the hollow push rod 25 and the reservoir 3|.

The cage 35 is generally cylindrical and is provided at its upper end with diametrically opposed radial tabs or ears 43 resting against the lower surface of the body member 43. The valve seat 44 is preferably formed in or at the end of a reduced extension of the body member 43 that fits within the cylindrical portion of the cage 35. The cage 35 is provided at its lower end with a bell shaped portion 41 serving as a guide for the ball 36. The tube 38, forming the cylinder within which the piston 31 operates, is provided at its upper end with a radial flange 48. The flange 48 is slotted at diametrically opposed portions for the reception of the tabs 43 on the ball cage 35. The cage 35 and cylinder 38 are so formed at the upper ends thereof that the tabs 46 on the cage 35 are positioned in the same plane as the flange 48 on the cylinder 38, the flange 48 and the tabs 46 being retained against the undersurface of the inner body member 21 by the spring 34. The cylinder 38 is of such diameter as to intimately engage the cylindrical portion of the cage 35 surrounding the reduced extension of the inner body member 21. The piston 31 is cup-shaped and presents a cylindrical portion intimately engaging the walls of the cylinder 38. The piston: 31 is retained within the cylinder 3.8 by means of an. inwardly directed; radial flange 49 at the lower end of the cylinder. The piston is provided with one, or more orifices or apertures 50 forming a passage for flow of fluid from the pressure lubricating system ofv the engine to the chamber 33 between the body members 21 and '29. The width or radial dimension of the flange 49 and the size and number of orifices or apertures 50 may be varied so as to vary the sensitivity of the piston 31, as will appear more fully hereinafter. It willnow be apparent that when the ball 36 is not seated against the valve seat 44, hydraulic fluid from the pressure lubricating-system of the engine will be forced from the reservoir 3| into the chamber 33 through the cylinder 38 and the pas sage 50 in the piston 31,. Continuous circulation, of lubricant through the lifter mechanism is provided for by a small radial passage 51 in the body member 43 of the inner body member 21, which bore or passage communicates with the reservoir 31 in the inner body member 21. Since the bore 5| is small in size, it forms a restricted passage for the flow of lubricant, which allows a slight continuous flow, but not such flow as will relieve the lubricant pressure in the chambers 3| and 33. Theradial passage 5| communicates at its outer end with a shallow circumferential groove 52 in the bodymember 43. A bore 53 in the outer body member 29 establishes communication between the circumferential groove 52 and a circumferential, groove 54 in the outer surface of the outer body member 29. The outer body member 29 has a relatively intimate engagement within the bore provided in the cylinder block, but sufficient clearance exists between the outer body member 29 and said bore to accommodate leakage of oil from the circumferential groove 54 to the lubricant reservoir or sump of the engine.

The manufacture and assembly of the valve lifter mechanism of the present invention are readily and economically accomplished. In assembly, the spring 34 is positioned in the bore 28 of the outer body member 29 and the cylinder 38 is positioned within the confines of the spring 34 with the flange 48 thereof engaging the upper end of the spring 34. The piston 31 is then positioned within the cylinder 38 and the spring at is positioned within the cylindrical portion of the piston 31. The ball cage 35 is then slid into the cylinder 38 until the tabs 46 engage the upper end of the spring 34. The ball 36 is then dropped into position and thereafter the body 43 of. the inner body member 21 is slid into the bore 28 of the outer body member 29, with the spring 39 positioned within a counterbore in the reduced extension at the lower end of the body 43. The body member 43 is slid into the outer body member 29 until the reduced lower extension thereof intimately engages within the cylindrical portion of the ball cage 35. The plug 45 may then be inserted into the inner body member 43, or the assembly of the plug 45 and body 43 may have been accomplished prior to. in-' sertion into the bore 28 of the outer body member 29. Thereafter, the snap ring 42. is inserted into the groove 4| in the bore 28 of the outer body member '29 to prevent accidental disassociation of the various members of the assembly.

The operation of the valve lifter mechanism l3 of the present invention is as follows:

With the engine valvein closed position, the

various elements of the mechanism willassu'me the relative positions shown in Figure 1, in which the spring 34 between the inner body member 27 and the outer body member 29 biases the flat bottom end of the outer body member 29 into engagement with the base circle portion of the cam 14 and normally biases the inner and outer body members away from each other but is capable of accommodating relative movement in either direction between the body members to establish and maintain zero clearance in the valve drive train [2.

- The

springs

39 and 40 are relatively light springs and may substantially counterbalance the efiect of one another upon the ball valve 36, or one spring may be stronger than the other so as to bias the valve toward or away from the valve seat. In one case, the spring 39 is slightly stronger than the spring 49 so as to normally bias the ball valve 36 to an open position, as shown in Figure 1. In another case, the valve 40 may normally bias the valve lightly to its seat, as will be appreciated from Figure 4. In either case, the

springs

39 and 40 also serve to retain the piston 31 in engagement with the flange 49 at the lower end of the cylinder 33. The entire mechanism is charged with fluid from the pressure lubricating system of the engine in the manner described hereinbefore.

As the cam rotates in a counterclockwise direction, as indicated by the arrow, an angular increment slightly in excess of 180 degrees from the position shown in Figure 1, the outer body member 29 is moved by the leading ramp of the cam [4 to rapidly build up the pressure within the chamber 33.

In the said one case, the radial flange of the cylinder is preferably narrow so that a large area of the piston 31 is exposed to the fluid in the chamber. The orifice 50 in the piston 3! is preferably formed of such restricted size, that the increase of pressure in the chamber 33 is not transmitted to the upper side of the piston 31 and, accordingly, the fluid pressure acting on the under surface of the piston moves same upwardly to compress the spring 49 to a sufiicient degree to overcome the eiTect of the spring 39, that is, to unbalance the spring tension on the ball,'and thusly to urge the ball 36 to its seat 44, as is shown in Figure 4. In addition, the movement of the piston 31 in the cylinder 38 causes an increase of pressure in the fluid within the cylinder 38, which is directed, by the bell shaped portion 41 of the cage 35, to the under surface of the valve 36 to assist in retaining the valve 36 on its seat 44. In moving the ball to its seat, only sufilcient force need be exerted to overcome the force difierential of the

springs

39 and 40, since the weight of the ball is balanced out by the spring 40. This is in contradistinction to commercial hydraulic valve lifters wherein fluid impact must be sufiicient to overcome the full weight of a solid steel ball. Accordingly, the size of the ball is of minor import in the present invention, whereas the size and weight of the ball in commercial hydraulic lifters is critical. In the said other case referred to hereinbefore, the valve is normally held lightly on its seat by the spring 49. Accordingly, if the orifice 59 in the piston 31 be large, or if several orifices be provided, the piston need not be actuated since the increase in fluid pressure will tend to hold the valve to its seat without leakage of fluid. However, it is preferred that the piston be actuated toincrease orsupplement the load on the spring 49 so that the ball will be positively held to its seat during actuation. As will now be apparent, sensitivity of piston response to increase in pressure may readily be varied by proper design of the size of the piston, the size or radial extent of the flange 49 and the size and/or number of piston orifices. At this point of actuation, in either case, the outer body member 29 has not been moved to any substantial degree by the cam I 4 and, accordingly, it is apparent that the fluid in the chamber 33 is trapped therein prior to actuation of the outer body member 29 by the lobe of the cam I4. Continued movement of thecam M in a counterclockwise direction forces the outer body member 29 upward and since the fluid in chamber 33 is substantially incompressible, the outer and inner body members will be moved conjointly to eflect actuation of the valve drive train [2 to open the engine valve H. During actuation of the valve drive train I2, the valve 36 is retained on its seat, as shown in Figure 4, until the cam has completed its work and the engine valve II has been moved to full open position and is returning to closed position.

I On further rotation of the cam I4 in a counterclockwise direction, toward the position shown in Figure 1, force on the outer body member 29 will be relaxed and the spring 34 and fluid in the pressure chamber 33 will bias the outer body member into engagement with the cam 14. The spring 34 and the fluid in the chamber 33 will tend to separate the body members to take up any clearance in the valve drive train, but will, if required, accommodate relative movement of the body members toward one another to eifectively shorten the valve drive train, thereby serving to correctly establish and maintain zero clearance in the valve drive train. Depending upon the size and number of orifices 50 in the piston 37, and to a degree upon the size of the piston, fluid pressures on opposite sides of the piston will be equalized after a predetermined time, at which the spring 39 and spring 40, in the one case, will cooperate to move the piston 31 downwardly to accommodate movement of the ball 36 off the seat 44 to open the port 32 for free passage of fluid from the reservoir 3| to the chamber 33, or vice versa as is required, according to adjustment made in the valve drive train. In the other case, after equalization of pressures, the spring 49 biases the piston 31 downwardly to relieve the spring so that the valve is lightly biased to its seat. Due to slight fluid leakby during actuation, the valve will readily accommodate passage of fluid through the port 32 whereby any necessary adjustment in the valve drive train is readily accomplished. The valve lifter mechanism is now in position to repeat the opening cycle just described.

From the foregoing, it will be appreciated that the piston is responsive to changes in fluid pressure within the chamber and that the restricted passageway in the piston provides means for equalizing pressures on opposite sides of the piston after a certain time interval so that the spring 40 or other biasing means may return the piston to its normal position after each actuation so as to insure relief of pressure on the check valve. The valve seat 44 cooperating with the ball 36 forms a limit stop for movement of the valve member in one direction and the flange 49 on the cylinder 38 cooperating with the piston 31 forms a limit stop for movement of the valve member in the opposite direction, as defined by the normal compression of the

springs

39 and 40. It is therefore apparent, that the actuation of the piston 31 and thus of the ball 36 must be identical upon each actuation of the valve lifter mechanism. The provision of limited and definitely defined movement of the ball check valve is of particular advantage since the clearance of the valve in the open position may .be set and established for an ultimate operating condition and yet only a limited amount of movement need be imparted to the valve to close the pressure chamber 33 upon each actuation of the valve lifter, which limited and defined movement can readily be accomplished during initial actuation of the outer body member 29 by the cam M.

Due to the fact that the aperture Sit in the piston 31 is preferably of restricted size, little, if any fluid is lost from the chamber 33 and, accordingly, the zero-lash condition established while the outer body member is riding the base circle of the cam will be substantially retained. During initial movement of the piston 3'! a small amount of fluid may escape from the interior of the cylinder 38 past the ball 36 before same is closed to accommodate a portion of the movement of the piston 31. Accordingly, the fluid in the cylinder 38 is not normally subjected to the same pressure increase as the fluid in the chamber the positions shown in Figure 4 during actuation of the mechanism. Some fluid leakage may occur during actuation of the lifter mechanism and, therefore, a very slight amount of clearance may exist in the valve drive train. Such clearance, however, is so slight as to be practically unmeasurable and, accordingly, in practical usage, zero clearance is maintained in the valve drive train.

The ball cage can be dispensed with, if desired, but the possibility would then exist that the ball could be laterally deflected out of registry with the valve seat M, with consequent failure, or substantial failure, of the mechanism to actuate the valve H. The provision of a conical spring for the spring means id is made to assist in retaining the ball 36 in alignment with the valve seat 44. The conical spring it may, in certain installations, be sufflcient to retain the ball in alignment with the seat M, but in normal internal combustion installations, it is preferred that the ball cage 35 or similar means be provided.

While reliance is placed, in the preferred embodiments of the present invention, upon a hydraulic impact characteristic, the ball valve is not directly responsive solely to fluid impact, as is the case in commercial hydraulic valve lifter, and the amount of impact necessary to actuate the check valve of the present invention is much less than that required in commercial hydraulic lifters. This advantage is obtained by utilization of the piston means and restricted passageway means of the present invention, the restricted passageway means facilitating the occurrence of a pressure diiierential on opposite sides of the piston means to effect closing of the valve in a substantially positive manner upon increase of pressure in the chamber 33. The area of the piston 31 exposed to the chamber 33, the radial extent of the flange 49, the force differential of the springs 39 and and the size and number of the apertures 56 may be varied to change the sensitivity of ball 33 and the valve and piston will remain in 7 seating and to provide a variety of operational characteristics.

The lifter of the present invention is particularly adapted for use with conventional engine cams having a gradual or slightly inclined ramp leading to the cam lobe, whereas commercial hydraulic lifters dispense with the leading or gradual-rising cam ramp in order to obtain the impact necessary for actuation of the check valve. While the present invention is capable of use with either type cam and provides a mechanism adapted for replacement of all lifter mechanisms utilized commercially, it is preferred that cams having a gradual-rising leading cam ramp be utilized in operation of the lifter mechanism of the invention. The utilization of such cams leads to increased life oi he cam and lifter and to more efiicient operation of the engine. Impact actuation of any lifter mechanism results in a greater wear and rapid destruction of the cams and mechanism and one object accomplished by the present invention is the avoidance of any necessity for sharp impact actuation.

Referring now to Figure 5, a further embodiment of the present invention is shown, wherein parts or elements similar or identical to parts or elements of the previously described embodiment of the invention have been indicated by the same reference numeral with the sufiix a. In this embodiment of the invention, the springs 39 and it acting directly upon the ball 36 are dispensed with. The ball check valve 36a is supported by a pedestal or stem 55 secured to the piston 37a. for actuation by the piston. The piston is urged downwardly against the flange .4911. on the cylinder 38a by a spring 56 confined between the piston and a radial flange 51 on the ball cage 35a. The upper end of the pedestal 55 is preferably dished so as to conformably receive the ball valve 36a. The operation of the lifter mechanism, shown in Figure ,5, is substantially identical to the operation of the lifter mechanism of Figures 1 to 4, in the case wherein the spring .39 biases the valve away from its seat, with the exception that the ball is positively moved to its seat upon actuation of the piston rather than being yieldably or resiliently urged to its seat.

In the embodiment of the invention shown in Figure 5, the ball cage 350. may be omitted, if desired, and this would be particularly advantageous if the ball 36a and the pedestal 55 comprised .a unitary member. If the valve member were a unitary member, as described, the ball would be positively aligned with its seat Ma and the ball cage 350 would be dispensed with. In this latter case, the spring 56 would be confined between the lower surface of the reduced extension of the body member 21a and the piston 31d.

In both embodiments of the invention, I have provided hydraulic valve lifter mechanisms hav ing the normal advantages of silent and efiicient operation, and in addition, having the advantages of maintaining substantially zero clearance in the valve drive train and substantially eliminating backlash therein. In both embodiments of the invention, I provide means for effecting seating of the check valve for the fluid pressure chamber in a substantially positive manner at least at the instant of actuation of the body members of the valve lifter mechanism. 1

From the foregoing description, it will appear that when the check valve is normally open, the same is uniformly actuated through a predetermined stroke regardless of the relative axial relation established between the inner and outer body proposed hydraulic valve lifters. ,vention is particularly adapted to be utilized in in the invention, the greater the separation of the inner and outer body members, the greater the stroke required of the valve. As the separation of the inner and outer body members increases,

the necessary stroke of the valve would correspondingly increase to an undesirable and impractical degree. As will also be noted from the foregoing description, the present invention provides an infinite zero-lash adjustment in either direction.

In both embodiments of the invention, opening of the check valve after actuation of the valve lifter mechanism is abetted by the pressure differential existing across the valve and accordingly, anybacklash existing in the valve drive train will be immediately taken up.

According to the present invention, the check valve for the fluid pressure chamber is closed by a, substantially positive hydraulic action.

Accordingly, the enginecam is preferably provided with gradualgrising leading cam ramps to the center point of the cam eccentric, so that the 'valve lifter mechanism is smoothly operated and is not subjected to the impact and shock necessary, for successful operation of commercially The present inthe replacement of all valve lifter mechanisms, whether mechanical or hydraulic. While it is preferred that the cam design be conventional, as shown in the drawings, it is clear that the present invention will operate satisfactorily with the particular cam design presently used for com mercial hydraulic valve lifters. While the life of "the apparatus undoubtedly will be decreased when utilized with impact type cams, the mechanism will operate just as efiectively to maintain zerolash adjustment and to eliminate backlash in the valve drive train.

In installing the valve lifter mechanism of the present invention in the valve drive train of an engine, it makes no difierence whether the engine be hot or cold during installation since overadjustment, which would normally occur if the engine were hot during installation, and underadjustment, which would normally occur if the engine were cold during installation, are readily compensated for and eliminated by the automatic operation of the valve lifter of the present invention.

,It will be apparent that various changes, modifications and rearrangements can be made in the particular apparatus described herein without departing from the scope of my invention. For example, a diaphragm or disc may be utilized as a check valve rather than a ball, one body member need not be mounted within another body member, the various parts and elements of the construction may be re-designed to fit particular installations or designs, and so on. Therefore, the embodiments of my invention, shown and described, are to be considered as capable of modi- 'fication and rearrangement within the spirit and scope of the invention, as defined by the appended claims.

' I claim as my invention:

1. A hydraulic valve lifter comprising a pair of relatively movable members defining a chamber therebetween, a source of fluid, a valve port in one of said members establishing communication between said source of fluid and said chamber, a check valve adapted to close said port, and piston means including a piston movable in said chamber and operatively associated with said upon increase of pressure in said chamber for urging said valve against said port, said piston means including means establishing communication between opposte sides of said piston for equalizing pressures on opposite sides of said piston in all positions of said valve.

2. A hydraulic valve lifter comprising a pair of relatively movable members defining achamber therebetween, a source of fluid, a valve port in one of said members establishing communication between said source of fluid and said chamber, a check valve adapted to close said port, cylinder means in said chamber, piston means movable in said cylinder means, said piston means being operatively associated with said valve and being adapted for actuation in one direction upon increase of pressure in said chamber for urging said valve against said port, at least one of said means providing a path of restricted flow between opposite sides of said piston means, and means biasing said piston rmeans in the opposite direction.

3. A hydraulic valve lifter comprising a pair of relatively movable members defining a cham: ber therebetween, a source of fluid, a cylinder in said chamber, a valve port in one of said mem-'- bers establishing communication between said source of fluid and said cylinder, a piston mov able in said cylinder, means establishing restricted communication between said cylinder and said chamber, a check valve adapted to close said port, said piston being operatively associated with said check valve and being adapted for actuation in one direction upon increase of pressure in said chamber for urging said valve against said port, and resilient means normally biasing said piston in the opposite direction.

4. A hydraulic valve lifter according to claim 3, in which said means establishing restricted communication between said cylinder andisaid chamber limits the flow of fluid from said chamber to said cylinder upon increase in pressure of the fluid in said chamber'to establish a'pressure differential on opposite sides of said piston and accommodates a slow equalization of pressures on opposite sides of said piston, whereby said piston is actuated by fluid in said chamber when the fluid pressure in said chamber is increased and after a time is returned to its normal'position by said resilient means.

5. A hydraulic valve lifter comprising a pair of relatively movable members defining a cham-' ber therebetween, a source of fluid, a cylinder in said chamber, a normally open valve port in one of said members establishing communication between said source of fluid and said cylinder, a piston reciprocal in said cylinder, and a check valve operatively associated with said piston and movable to close said port, said piston being exposed to said chamber and having at least one aperture therein establishing restricted communication between said cylinder and said chamber, said aperture limiting fluid flow from said chamber to said cylinder upon increase of pres sure in said chamber to establish a pressure differential on opposite sides of said piston, whereby said piston is actuated by the fluid in said chamber upon increase of pressure in said chamber to move said valve to close said port, said aperture accommodating flow of fluid from said chamber to said cylinder in all positions of said valve to equalize pressures on opposite sides of said piston and accommodate return movement of said piston and opening. of said port.

and adapted to be actuated upon increase oi pressure in said chamber to vary the bias of said resilient means said port. 1

'7. A hydraulic valve lifter comprising a pair of relatively movable members defining a chamber therebetween, a source of fluid, a cylinder in said chamber, a valve port in one of said members establishing communication between said source of fluid and said chamber, a check valve movable in said cylinder adapted to close said port, resilient means engag'ng opposite sides oi said valve to normally position said valve in predetermined relation with respect to said port, a piston movable in said cylinder and engaging the resilient means tending to bias said valve toward said port, and passageway means establishing restricted communication between said cylinder and said chamber, said passageway means limiting flow of fluid from said chamber to said cylinder upon increase of pressure in said chamber to establish a pressure differential on opposite sides of said piston, whereby said piston is actuated by the fluid in said chamber upon increase of pressure in said chamber to vary the bias of said resilient means and urge said valve against said port, said passageway means accommodating restricted flow oi fluid from said chamber to said cylinder in all positions of said valve to equalize fluid pressures on opposite sides of said piston.

8. A hydraulic valve lifter comprising a pair of relatively movable members defining a chamber therebetween, a source of fluid, a cylinder in said chamber, a normally open valve port in one of said members establishing communication between said source of fluid and said cylinder, a check valve movable to close said port, a piston reciprocal in said cylinder, a pedestal secured to said piston and supporting said valve, and passageway means establishing restricted communication between said cylinder and said chamber, said passageway means limiting flow of fluid from said chamber to said cylinder upon increase of pressure in said chamber to establish a pressure difierential on opposite sides of said piston, whereby said piston is actuated upon increase of pressure in said chamber to move said valve to close said port, said passageway means accommodating restricted flow of fluid from said chamber to said cylinder in all positions of said valve to equalize fluid pressures on opposite sides of said piston.

9. A hydraulic valve lifter mechanism for use in a valve drive train for a valve of an engine, the engine having a pressure lubrication system, comprising a pair of body members movable with respect to each other to maintain substantially Zero clearance in the valve drive train, said body members defining a chamber therebetween, a valve port in one of said members establishing communication between the engine lubrication system and said chamber whereby said chamber is constantly fllled with lubricating fluid, a valve member adapted to close said port whereby said to move said valve to close chamber is closed to prevent relative movement between said body members in one direction. piston means in said chamber and operatively associated with said valve for urging said valve against said port, said piston means being actuated upon increase of pressure in said chamber, the engine including means for moving onecf said body members toward the other body member to increase the pressure in said chambenand restricted passageway means establishing communication between opposite sides of saidpiston means in all positions of said valve to equalize pressures on opposite sides of :said piston after actuation thereof.

10. A valve lifter mechanism .forzuse in .a'valve drive train for opening and closing the valve-of an engine, said valve drive train ihaving'ifluid passageway means therein for connection'with the pressure lubrication system of the engine, comprising an outer body member having a bore therein, an inner body member :slidably mounted in the bore of said outer body member, said inner body member and said outer. bodymember defining a pressurechamber therebetween, a :cylinder in said pressure chamber, .a valve :port in said inner body member establishing communication between the fluid passageway means "of said valve drive train and said cylinder, a piston movable in said cylinder :and exposed to said chamber, passageway imeans establishing :restricted communication between said chamber and said cylinder, 'theifluid :forced to said pressure chamber from the pressure lubrication system of the engine acting to normally bias said body members away from each other and accommodating relative movement between said body members toward each other to maintain substantially zero clearance in the valve drive train in the closed position of the engine valve, and a valve member adapted to close said port in said inner body member, said piston being operatively associated with said valve member, the engine including cam means for engaging said outer body member to efiect movement of said body members toward one another to increase the fluid pressure in said chamber, said passageway means limiting flow of fluid from said chamber to said cylinder to establish a pressure differential on opposite sides of said piston whereby said piston is actuated in one direction upon increase of pressure in said chamber to urge said valve against said port, whereby said inner body member is moved conjointly with said outer body member by said cam means to open the valve of the engine, said passageway means accommodating restricted flow of fluid from said chamber to said cylinder in all positions of said valve to equalize fluid pressures on opposite sides of said piston after actuation thereof.

11. A hydraulic valve lifter mechanism according to claim 10, in which a first spring is confined between said inner body member and said valve and a second spring is confined between said piston and said valve, said springs normally retaining said valve in a predetermined position with respect to said port, said second spring normally biasing said piston in the opposite direction.

12. A hydraulic valve lifter mechanism according to claim 10, in which said valve has positive association with said piston, spring means being provided to normally bias said piston in the opposite direction.

13. A hydraulic valve lifter mechanism according to claim 10, wherein said valve is a ball freely 15 supported with respect to said piston, a cage being provided to retain said ball in alignment with said port.

14. A hydraulic valve lifter comprising a pair of relatively movable members defining a chamber therebetween, a valve port in one of said members establishing fluid communication between said chamber and the exterior of said members, a check valve adapted to close said port, and resilient means engaging opposite sides of said valve and normally resiliently biasing said valve to a predetermined position with respect to said port.

15. A hydraulic valve lifter comprising a pair of relatively movable members defining a chamber therebetween, a valve port in one of said members establishing fluid communication between said chamber and the exterior of said members, a check valve adapted to close said port, resilient means engaging opposite sides of said valve and normally resiliently biasing said valve to a predetermined position with respect to said port, and piston means in said chamber operatively associated with the resilient means to oneside of said valve, said piston means being responsive to changes in fluid pressure in said chamber for varying the biasing effect of said resilient means, said resilient means normally biasing said piston means to a. predetermined position, whereby said valve is normally maintained in its predetermined position.

16. A hydraulic valve lifter comprising a. pair of relatively movable members defining a chamber therebetween, a valve port in one of said members establishing fluid communication between said chamber and the exteriorof said members, a check valve adapted to close said port, piston means in said chamber responsive to variations in fluid pressure in said chamber, and a spring positioned between said piston and said valve for biasing said valve towards said port and said piston away from said port, said piston when actuated supplementing said spring for biasing said valve against said port.

17. A hydraulic valve lifter comprising a pair of relatively movable members defining a chamber therebetween, a source of fluid, a valve port in one of said members establishing communication between said source of fluid and said chamber, a check valve adapted to close said port, resilient means engaging opposite sides of said valve to produce a diiierential force thereagainst to seat said valve with respect to said port, and piston means operatively. associated with said resilient means and adapted to be actuated upon increase of fluid pressure in said chamber to supplement the diilerential biasing force of said resilient means to maintain said valve seated.

' GLENN T. RANDOL.

References Cited in the file of this patent UNITED STATES PATENTS