US3450228A - Hydraulic valve lifter - Google Patents

Description

June 17, 1969 E WORTMAN ET AL 3,450,228

HYDRAULIC VALVE LIFTER Filed July 19, 1967 flozzo/dfi Mari/2201; arrydM/arzazz 17/225 ZZZ 56/261 66 ATTORNEY United States Patent M 3,450,228 HYDRAULIC VALVE LIFTER Donald E. Wortman, Barry W. Norton, and Elias W.

Scheibe, Grand Rapids, Mich., assignors to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed July 19, 1967, Ser. No. 654,609 Int. Cl. F011 1/24; F01m 1/00; F16n 29/00 U.S. Cl. 1846 4 Claims ABSTRACT OF THE DISCLOSURE A push rod and rocker operating mechanism including a cam driven hydraulic valve lifter having side oil feed provisions which have direct open communication only intermittently with an oil pressure supply port in the tappet guide, and having a pressure responsive metering valve interiorly of the tappet which meters oil flow to the push rod and rocker, the cam engagement with the tappet being eccentric of the tappet axis to induce tappet rotation.

Background of the invention Our invention relates to lubricating systems for internal combustion engines and the like, and particularly to the use therein of hydraulic valve lifters and tappets having metering valve means to control lubricating oil flow to other parts of the mechanism such as push rods, valve rockers, etc. More specifically, the invention concerns improvements in such litters and tappets to effect interirnttent activation and consequent flushing of the metering valve so as to prevent its becoming blocked by foreign particles or sludge in the oil.

The prior U.S. Patents 2,818,060 to Papenguth, 3,151,- 603 to Schumm, and 3,280,807 to Bardy all show hydraulic valve lifters having such a metering valve arranged to move into and out of flow restricting abutment with the push rod seat, but only in response to inertia forces and the normal variations in oil pressure acting on the metering valve as occur from operation of the engine at different speeds. Also, U.S. Patents 2,948,270 and 3,111,- 119 to Bergmann, 3,128,749 to Dadd, 3,267,918 to Ayers and 3,291,107 to Cornell all show hydraulic valve lifters with a plate-like metering member under the push rod seat, but in each case such member is restrained against axial movement and its self-cleaning action is solely dependent on its relative rotation with the push rod seat.

While the metering valves of the type shown in the Papenguth patent which have freedom of axial or bodily movement into and out of abutment with the push rod seat have god self-cleaning properties under normal operating conditions in road vehicles, they show a tendency to become blocked by accumulation of grit and sludge in the oil when the engine is operated at one constant speed for a prolonged period. This can have serious consequences since lack of lubrication of the valve stems in their guides, for instance, could rapidly result in total engine failures.

By a novel arrangement of the side feed ports in the outer body of the tappet and in the tappet guide bore, and an annular external groove on the tappet body, we obtain an intermittent pulsing of the oil pressure acting on the metering valve with consequent activation or jiggling movement thereof, while at the same time providing for adequate feed of oil to the tappet during operating periods between such pressure pulses. The pulses occur in response to rotation of the tappet into and ut of positions where registry of the side ports in the tappet and guide can occur during the cam-induced reciprocatory movement of the tappet, and positive rotation of the Patented June 17, 1969 tappet for this purpose may be provided by offsetting its cam engagement eccentrically of the tappet axis. The external groove on the tappet, which may have either continuous or only intermittent registry with the guide port as desired, is spaced longitudinally of the tappet from the tappet port. In either case, the spacing of the groove from the tappet port is sufliciently small that the sliding-fit clearance of the tappet in its guide is adequate within the distance established by that spacing to accommodate at least the minimum feed requirements for the lubrication purposes.

Brief description of the drawing FIGURE 1 is a cross-sectional view of a portion of an internal combustion engine illustrating application of our invention wherein engine oil supplied under pressure to a hydraulic tappet is delivered through the hollow push rod to the overhead valve and rocker mechanism.

FIGURE 2 is an enlarged fragmentary sectional view showing internal parts of the tappet and its side oil feed provisions.

FIGURE 3 is a fragmentary elevational view taken in the direction of the arrows 3-3 in FIGURE 1, showing the centric relation of the cam engagement with the tappet.

Description of the preferred embodiment Referring now in detail to the drawing, the engine shown in FIGURE 1 is of the V-type including a cylinder block and crankcase 1, in each side of which one or more cylinders 2 are provided and closed at their upper ends by a cylinder head 3. Suitably journaled in the crankcase is an engine driven cam 4 which operatively engages a tappet 5 so as to cause it to reciprocate in a suitable support shown as a bore 6 formed in the crankcase. An engine poppet valve 7, having a stem 8 reciprocably supported in a valve guide bore 9 formed in the cylinder head, is biased to its closed position shown by a return spring 10. The valve 7 is operatively connected to the tappet 5 by a valve rocker 11 and a hollow push rod 12. The particular valve rocker illustrated is in the form of a generally channel-shaped metal stamping having downwardly presenting opposite end surfaces 13 and 14 in bearing engagement with the upper ends of the push rod and poppet valve respectively, and an intermediate upwardly presenting bearing surface 15 journaling on a bearing member 16 which is fixed to the cylinder head by a stud 17 and nut 18. It will be appreciated that the rocker bearing surfaces 13, 14 and 15 and the sliding surfaces of the valve stem 8 and its guide 9 all require lubrication during operation of the engine. Oil therefor is supplied via the tappet 5 through the hollow push rod 12, and in metered amounts, as hereinafter described.

Referring to FIGURE 2, the hydraulic tappet 5 comprises a cup-shaped outer body member 20 having a cup-shaped plunger 21 telescopically slidable therein and defining an oil pressure or cushion chamber 22 between their respective closed ends. Within this pressure chamber and biasing the plunger outwardly of the outer body member is a plunger spring 23. The interior of the plunger forms a reservoir chamber 24 for supplying the pressure chamber 22 through a check valve controlled passage 25. Secured to the lower end of the plunger by the plunger spring 23 is a cage 26 which loosely confines the check valve 27. During each lift stroke of the outer body member 20 by the cam 4, oil is trapped in the pressure chamber by closure of the passage 25 by the check valve 27 and the plunger is forced to travel upwardly, carrying with it the push rod seat 28 and the push rod 12. The upward movement of the push rod causes the rocker to fulcrum on the bearing member 16 and open the poppet Valve 7 against its spring 10. During each such cam lift 3 stroke, a small amount of the oil trapped in the pressure chamber 22 of the tappet escapes around the plunger, which leakage is termed leak down and is necessary in order to insure that the poppet valve 7 may fully close on the subsequent return stroke, which occurs with continued rotation of the cam 4.

After the poppet valve 7 closes, the plunger spring 23 continues to maintain the tappet outer body member 20 in contact with the surface of the cam while holding the plunger in abutment with the push rod seat to take out all lash in the system. While the outer body member 20 is regaining its engagement with the base circle of the cam, the plunger is therefore moved outwardly (i.e. upwardly relative to the member 20) to compensate for all or substantially all of its leak-down movement inwardly of the member 20 during the lift stroke. This results in reenlarging the pressure chamber and oil flowing thereinto past the then open check valve 27 from the reservoir chamber 24.

The plunger is provided with an external groove 29 and a side port 30 leading therefrom to connect with the reservoir chamber 24. A major portion of the leak-down oil escaping around the plunger during the lift stroke re-enters the reservoir chamber through the plunger groove 29 and its side port 30. However, in order to insure that the reservoir chamber is maintained full at all times for necessary replenishment of the pressure chamber 22 and delivery of oil through the hollow push rod for lubricating the valve rocker and valve stem, provisions are made for an inlet to the reservoir chamber through the outer body member 20 to connect the plunger groove 29 with the pressure lubricating system of the engine. These provisions, as shown, include an internal annular groove 31 in the body member 20 having continuous registry with the plunger groove 29 throughout the range of relative reciprocal movement of the plunger and mem- -ber 20 in operation. Intersecting the internal groove 31 and leading to the outer periphery of the outer body member 20 is a side port 32. Spaced longitudinally a short distance from this port 32 is an external annular groove 33 formed in the body member 20, and having registry via a recess 34 with a port 35 in the tappet guide 6. In the specific embodiment shown, this registry between the groove 33, recess 34 and guide port 35 is continuous throughout the range of the reciprocatory movement of the tappet 5, however interruption of such registry may be provided if desired, as by relocating the body port 32 and its external groove 33 so that the groove 33 will lie above or below the recess 34 during a portion of the tappet stroke. The guide port 35 is supplied with oil from the gallery 36 which extends longitudinally of the engine crankcase 1 and forms part of the oil pressure lubricating system of the engine.

Although the tappet body external groove 33 is supplied with oil under pressure from the gallery 36, port 35 and recess 34 during at least a portion of each stroke of the tappet irrespective of the angular or rotative orientation of the tappet in its guide, such is not true with respect to the tappet body port 32. Registry of this port with the recess 34, it will be appreciated, may only occur when the tappet is rotatively oriented to its position shown in FIGURE 2. When not so oriented, the oil pressure supply to the reservoir via the tappet and plunger ports 32 and 30 is dependent upon that accommodated by the sliding-fit clearance of the tappet body 20 in its guide. This clearance, however, is adequate within the relatively short spacing between the tappet port 32 and external groove 33 to accommodate at least the minimum feed requirements of the tappet, including that necessary for the lubricating oil flow upwardly through the push rod seat 28 to the push rod 12. The flow during such periods of non-registry of the tappet port 32 with the guide port 35 via the recess 34 is, of course, relatively restricted in comparison with the flow rate when such registry occurs. Also, the oil pressure existing in the reservoir chamber is consequently increased considerably each time such direct registry of the tappet port 32 occurs, and the resulting pressure pulses serve an important purpose to be hereinafter described.

Rotation of the tappet during reciprocation generally occurs as a normal consequence of there being at least a slight offset relation between its engagement by the earn 4 and the longitudinal axis of the tappet. To insure that such tappet rotation will be positive the tappet of the instant invention is given a definite such offset. This is shown (exaggerated for clarity) in FIGURE 3 wherein the offset or eccentricity of the tappet is represented by the spacing between the plane C which passes through the effective point of engagement between the tappet and cam, and the axis T of the tappet.

The upper end of the plunger is counter-bored to receive the push rod seat 28 which is flanged at its upper end to rest on the open end of the plunger. The shoulder 37 formed by this counterbore acts as a retainer for a plate-like flow control valve 38 which serves to meter oil flow to the push rod from the reservoir 24 through a central outlet 39 in the push rod seat. The plate-like valve 38 has lateral and axial clearance for bodily movement within the counterbore and between the shoulder and the push rod seat. Either of the opposing surfaces of the valve member and push rod seat is preferably formed with a single axis curvature in the manner shown and described in the aforementioned Papenguth patent, whereby such bodily movement of the valve effects a variable restriction of the oil flow through the outlet 39 in the push rod seat. Such movement of the valve is induced by the inertia and oil pressure forces working thereon during engine operation. During normal operation of the engine at varying speeds, as in a road vehicle, the forces producing such bodily movement of the valve 38 are sufficiently varying that it is effectively self-cleaning. However, under conditions of prolonged operation at one constant speed a tendency exists for sludge and grit accumulating in the oil to build up between the valve and around the push rod seat aperture 39, causing blockage of the oil flow therethrough to the push rod, valve rocker etc. By reason of the pressure pulses, which occur each time the tappet rotates into registry with the guide recess 34 and port 35, increased and rapid upward bodily movement of the valve 38 takes place, acting to crush or dislodge any foreign particles between it and the area of the push rod seat adjacent the aperture 39. Upon further rotation of the tappet suflicient to interrupt such direct registry with the port 32 the oil pressure in the reservoir chamber is again reduced, resulting in the valve 38 moving further away from the push rod seat and thereby flushing the valve and aperture 39 for freer passage of oil.

We claim:

1. In a lubricating system for an engine or the like including a reciprocatedly actuated tappet having an oil chamber with an inlet opening and an outlet opening, a bearing surface external of the tappet and in fluid communication with said outlet opening, guide means slidably supporting the tappet for axial rotation and reciprocation, means for conducting oil under pressure to the tappet including a port in said guide means, said port having registerability with the inlet opening during a portion only of the reciprocatory stroke of the tappet and said registerability being dependent on the rotative orientation of the tappet being such that both the port and inlet opening are on the same side of the tappet, said tappet having an external annular groove registerable. with said port during at least a portion of the reciprocatory stroke of the tappet, said groove being spaced longitudinally of the tappet from the inlet opening whereby when the groove is in registry with the port and the inlet opening is out of registry with the port oil flow into the chamber is restricted to that accommodated by the sliding-fit clearance between the tappet and guide means, a seat in the chamber defining the chamber-end of one of said open- 5 ings, and a valve in the chamber movable into and out of abutment With said seat in response to oil pressure in the chambe; and inertia :forces acting on the valve in response to reciprocation of the tappet.

2. The invention of claim 1, wherein said seat defines the chamber-end of said outlet opening.

3. The invention of claim 1 including a tappet end face and an actuating cam having operative engagement with said end face, the eifeotive plane of said engagement being spaced from the axis of rotation of the tappet whereby said cam induces rotation of the tappet during tappet reciprocation.

4. The invention of claim 1, wherein said tappet groove is in continuous registry With said guide means port throughout the reciprocatory stroke of the tappet.

References Cited UNITED STATES PATENTS Scheibe 12390 Ayres 1846 XR Bardy 184-6 XR Bertsch et a1 123-90 Abell 1846 XR Kabel et al 184--6 XR Thompson 1846 XR MILTON KAUFMAN, Primary Examiner. MANUEL ANNTONAKAS, Assistant Examiner.

US. Cl. X.R.

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