US3605707A

US3605707A - Hydraulic valve lifter with pump-up prevention means

Info

Publication number: US3605707A
Application number: US882224A
Authority: US
Inventors: Gerald D Line
Original assignee: Eaton Yale and Towne Inc
Current assignee: Eaton Corp
Priority date: 1969-12-04
Filing date: 1969-12-04
Publication date: 1971-09-20
Anticipated expiration: 1988-09-20

Abstract

A HYDRAULIC VALVE LIFTER INCLUDES BODY AND PLUNGER MEMBERS WHICH COOPERATE TO DEFINE A PRESSURE CHAMBER. THE HYDRAULIC VALVE LIFTER INCLUDES MEANS FOR PREVENTING "PUMP-UP" OF THE LIFTER UNDER THE INFLUENCE OF SURGING OF AN ENGINE VALVE SPRING AND FOR MINIMINZING LASH IN THE VALVE TRAIN AT COLD ENGINE STARTING CONDITIONS. THE MEANS FOR PREVENTING "PUMP-UP" INCLUDES A CHECK VALVE MEMBER, MOVABLE BETWEEN A FIRST LIMIT POSITION IN WHICH THE VALVE MEMBER BLOCKS A FLOW OF FLUID TO THE PRESSURE CHAMBER AND A SECOND LIMIT POSITION IN WHICH THER IS A RESTRICTED FLOW OF FLUID TO THE PRESSURE CHAMBER. THE RESTRICTED FLOW

OF FLUID PREVENTS "PUM-UP" OF THE LIFTER DURING SURGING OF THE ENGINE VALVE TRAIN AND ALSO PREVENTS LASH IN THE VALVE TRAIN DURING COLD ENGINE STARTING CONDITIONS.

Description

Sept. 20, 1971 G. D. LINE 3,605,707

HYDRAULIC VALVE LIFTER WITH PUMP-UP PREVENTION MEANS Filed Dec. 4, 1969 3 Sheets-Sheet l 32 a6 saw I 3;; FIGS 60: //VV/V7'0/? 48 @ERALD 0 LINE G. D. LINE 3,605,707

HYDRAULIC VALVE LIFTER WITH PUMP-UP PREVENTION MEANS Sept. 20, 1971 3 Sheets-Sheet 2 Filed Dec. 4, 1969 5 mw NL a W 0 m m G Sept. 20, 1971 G. D. LINE 3,605,707

HYDRAULIC VALVE LIFTER WITH PUMP-UP PREVENTION MEANS Filed Dec. 4, 1969 3 Sheets-Sheet 3 F (I Ii g y 1% FIG/IO /A/VEN7'0R GERALD Q LM/E ATTOR/VE Y3 United States Patent Clfice 3,605,707 Patented Sept. 20, 1971 3,605,707 HYDRAULIC VALVE LIFTER WITH PUMP-UP PREVENTION MEANS Gerald D. Line, Saginaw, Mich., assignor to Eaton Yale & Towne Inc., Cleveland, Ohio Filed Dec. 4, 1969, Ser. No. 882,224 Int. Cl. F011 1/24 US. Cl. 123-9057 1 Claim ABSTRACT OF THE DISCLOSURE A hydraulic valve lifter includes body and plunger members which cooperate to define a pressure chamber. The hydraulic valve lifter includes means for preventing pump-up of the lifter under the influence of surging of an engine valve spring and for minimizing lash in the valve train at cold engine starting conditions. The means for preventing pump-up includes a check valve member, movable between a first limit position in which the valve member blocks a flow of fluid to the pressure chamber and a second limit position in which there is a restricted flow of fluid to the pressure chamber. This restricted flow of fluid prevents pump-up of the lifter during surging of the engine valve train and also prevents lash in the valve train during cold engine starting conditions.

The present invention relates to a hydraulic valve litter, and more particularly to a hydraulic valve lifter having a check valve assembly which prevents pump-up of the lifter during valve spring surging which occurs at high vehicle speeds.

A known hydraulic valve lifter used in internal combustion engines includes a valve lifter body and a plunger member slidably received therein and defining a fluid chamber therewith. A check valve is provided to control the flow of fluid to the fluid chamber to thereby control the effective length of the lifter. The check valve assembly of the known lifters allows the effective length of the lifter to increase excessively so that pump-up of the lifter occurs during high speed operation of the engine when the valve closing spring for the engine valve reaches critical speeds Where the natural frequency of the spring is at a low harmonic of the valve train operating frequency. This condition causes the valve train to surge and allows momentary separation of the valve train. During periods of valve train surge, an intermittent unseating of the check valve occurs permitting a build-up of fluid in the pressure chamber of the known lifter to a point where the hydraulic valve lifter elongates excessively or pumpsup. This excessive elongation results in continual unseating of the engine valve and a loss of horsepower.

Attempts have been made to correct pump-up in conventional hydraulic valve lifters. One attempt to prevent pump-up in a hydraulic valve lifter utilizes a check valve that automatically closes and prevents fluid flow to the pressure chamber when surging of the valve train occurs. This type of litter, illustrated in the Donnelly et al. Patent No. 3,406,668, suffers from the disadvantage that at cold engine starting conditions noise is created in the valve train.

The Donnelly Patent No. 3,406,668 includes a check valve member which controls the flow of lubricant into a pressure chamber which is defined by the plunger and body member of the lifter. The flow of fluid into the pressure chamber controls the elongation of the valve lifter. In order to solve the problem of excessive pump-up, due to engine valve spring surging, the Donnelly construction provides for the check valve to block the flow of fluid into the pressure chamber at its limit position, to which it is moved on upward movement of the plunger body. Since the check valve closes off flow to the pressure chamber in this limit position, excessive pump-up of the litter is prevented.

However, since the lubricant in the pressure chamber leaks therefrom when the engine is not operating, a problem of noise at cold engine starting conditions results. The valve lifter, as noted above, will be somewhat in a collapsed condition at cold engine starts. During initial starting, the check valve will move toward its limit position and block the flow of fluid into the pressure chamber. As a result, an amount of fluid will flow into the chamber which is insufficient to take up the lash in the valve train during the cold engine start. Accordingly, noise in the valve train results in the Donnelly construction.

Moreover, since the lubricating fluid has a high viscosity under cold engine starting conditions, the noise problem caused by the check valve blocking fluid flow into the ressure chamber is compounded, since the lubricating fluid will not flow rapidly past the check valve even when it is opened. This further minimizes the amount of fluid flow into the pressure chamber and the time lapse for providing a suflicient volume of fluid in the pressure chamber to take up lash in the valve train.

The present invention is directed to the problem of preventing valve lifter pump-up during surging of the valve train and is also constructed to solve the problem of noise during cold engine starts. This is effected in the present invention by, in general, providing a restricted flow of fluid past the check valve member and into the pressure chamber at the limit position to which the check valve member moves from its valve seat. As a result, the check valve member in its limit position does not block or prevent all fluid from flowing into the pressure chamber. However, the flow of fluid that is permitted to flow in this limit position is a restricted or limited flow. This restricted flow is low enough to minimize pump-up of the valve lifter during surging of the valve spring, but, yet, is great enough to provide for relative rapid elongation of the lifter to take up lash in the valve train during cold engine starts.

A characteristic of the operation of a litter having the advantageous flow in accordance with the present invention is that the plunger member will slowly move upward in the lifter, as opposed to the prior art hydraulic valve lifters where the plunger moves upward substantially instantaneously. In fact, as compared to the prior art where the plunger returns instantaneously the plunger of the present construction returns at approximately one-fourth the rate at which the plunger of the prior art returns.

Accordingly, it is an object of the present invention to provide a new and improved hydraulic valve lifter which overcomes the hereinabove noted deficiencies of the prior art by including a check valve assembly which prevents pump-up of the lifter during surging of the engine valve train and which minimizes lash in the valve train at cold engine starting conditions.

Another object of the present invention is to provide a new and improved hydraulic valve lifter having a check valve assembly for controlling the flow of fluid into a pressure chamber in the valve litter and which check valve assembly includes a valve member movable from a first limit position blocking the flow of fluid to the pressure chamber to a second limit position in which the valve member provides for a restricted flow of fluid into the pressure chamber which is sufiiciently great to minimize lash in the valve train at cold engine start conditions and is low enough to prevent pump-up of the lifter when surging of the engine valve train occurs.

Still another object of the present invention is to provide a new and improved hydraulic valve lifter for use in an internal combustion engine for opening and closing an engine valve which is biased toward a closed position by an engine valve spring and which lifter includes a body member and a plunger member which cooperate to define a pressure chamber therebetween and means defining a passageway for directing fluid to the pressure chamber, and wherein a check valve member controls the effective cross-sectional area of the passageway to thereby control the flow of fluid into the pressure chamber and wherein the valve member moves from a first limit position blocking the flow of fluid through the fluid passageway through a position in which the passageway has a maximum effective cross-sectional area to a second limit position in which the passageway has a predetermined relatively small cross-sectional area when surging of the engine valve train occurs to thereby restrict the flow of lubricant to the pressure chamber and prevent pumpup of the lifter.

A further object of the present invention is to provide a new and improved hydraulic valve lifter, as noted in the next preceding paragraph, wherein the check valve assembly provides for a restricted flow of fluid to the pressure chamber at cold engine starting conditions to thereby prevent lash in the valve train and noisy operation thereof.

Still another object of the present invention is to provide a new and improved hydraulic valve lifter, as noted above, having a pressure chamber and a check valve assembly including a check valve member biased by a spring member toward a first limit position blocking the flow of lubricant to the pressure chamber and movable against the force of the spring member to a second limit position in which the check valve assembly provides for a restricted flow of lubricant to the pressure chamber, the flow of lubricant tothe pressure chamber flows through the spaced coils of the spring member so that movement of the check valve member away from the first limit position to the second limit position compresses the spring and reduces the space between the coils thereof to thereby restrict the effective cross-sectional area of the flow path through which the fluid flows to the pressure chamber so that the fluid flow to the pressure chamber is restricted thereby.

A further object of the present invention is to provide a new and improved hydraulic valve lifter, as noted in the next preceding paragraph, further including a check valve retainer member in which the check valve member and the spring member are located and wherein the retainer member includes a projection thereon with which the valve member abuts upon movement to its second limit position to thereby provide a positive stop for the valve member when the spring member is fully compressed so as to prevent damage to the spring member.

Another object of the present invention is to provide a new and improved hydraulic valve lifter for use in an internal combustion engine for opening and closing an engine valve and which includes a check valve assembly for restricting the flow of lubricant to a pressure chamber, the check valve assembly includes a check valve member and a fluted check valve retainer, the check valve member is movable from a first limit position in which it blocks the flow of lubricant to the pressure chamber to a second limit position in which it engages with the fluted retainer member and at which position a restricted flow of lubricant flows to the pressure chamber.

Still another object of the present invention is to provide a new and improved hydraulic valve lifter for use in an internal combustion engine for opening and closing an engine valve and which includes a check valve assembly including a check valve member and a check valve retainer having an opening in the side thereof to provide for fluid flow to the pressure chamber, the check valve member having a first limit position in which it blocks the flow of fluid to the pressure chamber and a second limit position in which the valve member moves toward the side of the retainer member having the opening to thereby restrict the flow of lubricant to the pressure chamber and prevent pump-up" of the filter during surging of the valve train and excessive lash in the valve train at cold engine starts.

Further objects of the present invention will be apparent from the following detailed description of a preferred embodiment of the present invention made with reference to the accompanying drawings and forming a part of the specification and wherein:

FIG. 1 is a schematic view of a hydraulic valve lifter and related assemblies in an engine block of a V-type internal combustion engine;

FIG. 2 is a cross-sectional view of an embodiment of the invention taken approximately along the lines 22 of FIG. 1;

FIG. 3 is a cross-sectional view of a portion of the valve lifter shown in FIG. 2 and illustrating the check valve member in a position in which the flow of lubricant to the pressure chamber is restricted;

FIG. 4 is an enlarged cross-sectional view of another embodiment of the present invention showing a check valve assembly including a fluted cone shaped retainer;

FIG. 5 is a sectional view taken approximately along the line 55 of FIG. 4 and further illustrating the fluted configuration of the retainer member;

'FIG. 6 is an enlarged cross-sectional view of still another embodiment of the present invention;

FIG. 7 is an enlarged cross-sectional view of another embodiment of the present invention illustrating a check valve assembly including a check valve retainer having a projection formed thereon for engaging with the valve member and providing a positive stop therefor;

FIG. 8 is an enlarged cross-sectional view of yet another embodiment of the present invention;

FIG. 9 is an enlarged cross-sectional view of another embodiment of the present invention showing a check valve providing for a restricted lubricant flow to the pressure chamber; and

FIG. 10 is another view of the embodiment of FIG. 9 showing the valve member in a flow restricting position.

The present invention provides an improved hydraulic valve litter, and more particularly an improved check valve assembly in a hydraulic valve lifter which presents pump up of the lifter and also minimizes lash in the valve train at cold engine start-up conditions to thereby provide quiet operation of the valve train. The check valve assembly includes a valve member for controlling the cross-sectional area of a fluid passageway through which the fluid must flow to the pressure chamber to thereby at least partially control the flow of fluid to the pressure chamber. The valve member has a first limit position in which the flow of fluid to the pressure chamber is blocked and is movable to a second limit position in which the fluid passageway has a predetermined minimal eflective cross-sectional area which provides for restricted flow of fluid to the pressure chamber. During operation of the lifter, the valve member normally moves from the first limit position and fluid flows to the pressure chamber in a well-known manner. During the occurrence of excessive surging of the engine valve spring and during cold engine starts, the valve member moves to the second limit position in which the crosssectional area of the passageway has a predetermined effective cross-sectional area which provides for a restricted fluid flow to the pressure chamber to thereby prevent pump-up of the lifter under the influence of excessive surging of the engine valve train. The restricted flow when the valve member is in its second limit position is sufficient to substantially minimize lash in the valve train during cold engine starts and thereby prevent noise on cold engine starts.

A valve lifter embodying the present invention may have a variety of constructions. This application discloses diflerent embodiments of the invention, and FIG. 1 illustrates a hydraulic valve lifter 10 embodying the present invention.

The hydraulic valve lifter 10, as illustrated in FIG. 1, controls the movement of an engine valve 20. The valve 20 controls the flow of gases into and from the combustion chamber 14 of the cylinder of the engine. The valve member 20 is moved between open and closed positions with respect to a valve seat 20a by a valve train, generally designated 21.

The valve train 21 is actuated by a cam 9 which engages the hydraulic valve lifter 10. The cam 9 consists of a circular portion 11 and a raised portion 13, which rotate with a cam shaft 12. The bottom of the lifter 10 engages with cam 9 which imparts motion to the lifter during rotation thereof. The cam 9 may rotate in either a clockwise or a counterclockwise direction, as viewed in FIG. 1, but for illustrative purposes will be described as rotating in a clockwise direction so that an upward motion is imparted to the lifter 10 as the ramp 13a of the cam 9 engages and moves relatively to the lifter 10. An upward motion of the lifter 10 effects an upward movement of the valve train 21 and opening of the valve 20. When the ramp 13b engages with and moves relatively to the lifter 10, a downward movement of the lifter 10 and of the valve train 21 is eflected. The downward movement of the valve train 21 results in closing of the valve 20.

The valve train 21 includes a push rod 15 interposed between the lifter l and a rocker arm 17. Movement of the push rod 15 upwardly by the lifter causes the rocker arm 17 to pivot about a bearing 18 and effect opening of the valve 20. The push rod has a tubular passageway 16 which allows lubricant to flow therethrough from the valve lifter 10 to the bearing 18 of the rocker arm. When the rocker arm 17 is raised by an upward movement of the push rod 15 acting on a shoulder 17a thereof, the rocker arm 17 pivots about the bearing 18 and a shoulder 17b of the rocker arm 17 exerts a downward force to open the avlve 20. An engine valve spring 19 biases the shoulder 17b upwardly so that when the ramp 13b engages with the bottom of the lifter, the spring 19 effects an upward movement on the shoulder 17b to engage valve 20 with the valve seat 20a and cause the rocker arm 17 to pivot and thereby cause the push rod 15 and valve lifter 10 to move downwardly.

As is known, the hydraulic valve lifter 10 adjusts the valve train 21 to maintain a predetermined relationship between the rocker arm 17 and the cam 9 even though the dimensions of the valve train 21, rocker arm 17, valve 20 and the cam 9 may vary due to wear, thermal effects, etc. To this end, the hydraulic valve lifter 10 includes a generally cylindrical cupped shaped body member as illustrated in FIG. 2. The cupped shaped body member 30 has a closed end 31 which is engaged by the cam 9, as shown in FIG. 1. Disposed within the hollow body member 30 are a plunger member 32 and a push rod socket member 33 having a push rod seat 34. Seated in the push rod seat 34 is the push rod 15. A snap ring 41 is disposed in an angular groove 41a in an upper portion 35 of the hollow body member 30 to hold the parts of the lifter within the body member 30.

The plunger member 32 at least in part defines a lubricant reservoir 40. Lubricant is pumped into a passageway 42 in the portion 35 of the body member 30 by some suitable means, not illustrated, such as a pump. The passageway 42 communicates with an annular groove 43 in the portion 35 of the body member 30 which in turn communicates with a slotted passageway in the socket member 33 to allow lubricant to flow into the reservoir 40. Therefore, during normal operations the reservoir 40 is filled with lubricant.

The hydraulic valve lifter 10 provides for lubricant flow through the push rod passage 16 to the rocker arm 17, in any well-known manner. In the illustrated embodiment the socket member 33 has an annular peripheral surface 38 upon which is located an inlet 38a. A radially extending passageway 37 is interposed between the inlet 38a and a perpendicular passageway 36. The perpendicular pas- 6 sageway 36 has an outlet 36a which is in communication with the push rod seat 34'. The lubricant in the annular groove 43 is directed through the

passageways

37 and 36 to the push rod seat. The lubricant then flows through the push rod passageway 16 to the rocker arm 17 to effect lubrication thereof.

The reservoir 40 communicates with a pressure chamber by means of a passageway 46 located in the lower end of the plunger member 32. Disposed within the pressure chamber 60 is a check valve assembly generally designated 47. The check valve assembly 47 includes a check valve retainer cup 48, a check valve spring 50, and a check valve member 52. The check valve member 52 is a spherical shaped ball member. The ball 52 is located within the retainer cup 48 which is suitably connected to the plunger member 32 at the shoulder 49. The check valve spring 50 abuts with the bottom of the check valve retainer cup 48 and biases the ball member 52 upwardly to a first limit position in which the ball 52 engages with a valve seat 46a formed at the lower end of the passageway 46.

The check valve assembly 47 cooperates with the plunger member 30 and the socket member 33 to compensate for dimensional changes in the valve train 21 by varying the axial extent of the hydraulic valve lifter 10 to thereby maintain the predetermined relationship between the cam 13, rocker arm 17 and valve 20. To this end, the check valve assembly 47 controls the flow of lubricating fluid to the pressure chamber 60 to thereby control the axial extent of the lifter 10.

The position of the check valve member 52 is controlled by the spring 50 and fluid pressure forces acting thereon. The pressure within the pressure chamber 60 and the spring 50 exert an upward force on the valve member 52. This upward force is opposed by the fluid pressure acting on the valve member 52 from the reservoir 40. When the downward force acting on the check valve member 52 from the reservoir 40 is less than the force acting on the check valve member 52 due to the pressure in the pressure chamber 60 and the force exerted by spring member 50, the valve member 52 engages the valve seat 46a to prevent the flow of lubricant therethrough. When the force acting on the check valve member 52 from the reservoir 40 is greater than the force due to the pressure in the pressure chamber 60 and the force exerted by the spring member 50, the valve member 52 is moved downwardly and allows lubricant to flow into the pressure chamber 60.

When the body member 30 is moving in a downwardly direction off the raised portion of the cam 13, the plunger return spring 51 eflFects relative movement between the plunger 32 and body member 30 to enlarge the pressure chamber 60 and reduce the pressure therein. As a result, the pressure acting on the check valve member 52 from the reservoir 40 moves the valve member downwardly away from the valve seat 46a against the influence of the pressure in the chamber 60 and the check valve spring 50. This enables fluid to flow from the fluid reservoir 40 into the pressure chamber 60.

When the body member 30 is again moved upwardly by the cam 13, the fluid pressure in the chamber 60 is increased. This is due to the upward movement of the body member 30 relative to the plunger member 32 which compresses the plunger return spring 51 and effects a decrease in the volume of the pressure chamber 60. The increase in pressure in the chamber 60 and the force of the check valve spring 50 combine to overcome the force exerted by the pressure from the reservoir 40 acting on the valve member 52 to allow the member 52 to again seat against the valve seat 46a and stop the flow of fluid from the reservoir 40 into the pressure chamber 60'.

When the check valve assembly 47 closes passageway 46 due to an upward movement of the body member 30, the lubricant in the pressure chamber 60 is essentially sealed therein. The lubricant sealed within the pressure chamber 60 is substantially incompressible and, therefore, when the hollow body member 30 is raised the lubricant in the pressure chamber .60 will exert an upward force which resists downward movement of the plunger member 32 relative to the body member 30'. As a result, the plunger member 32 moves in an upward direction thus, opening the valve 20 as described hereinabove.

During each valve opening stroke, small amounts of lubricant trapped in the pressure chamber 60 escape or leak around the plunger 32 through a small space 62 disposed between the body member and the plunger member. The leakage is termed leak-down and is necessary in order to insure that the valve 20 can be fully seated on subsequent return strokes which occurs with continued rotation of the cam 9. Were it not for this leak-down during each lifting stroke, if any of the parts of the valve train lengthened, due to an increase in temperature, such greater length would hold the engine valve 20 slightly ofi its seat 20a and effect a decrease in efliciency of the engme.

It should be realized that the check valve assembly 47 controls the effective length of the valve lifter 10. Thus, if the eifective length of the valve train 21 should increase from one revolution of the cam 9 to the next, the distance which the plunger spring 51 moves the plunger 32 and the socket 33 and the amount of replacement fluid which flows into the pressure chamber 60 is decreased to thereby decrease the elfective axial length of the lifter 10. Conversely, if the effective length of the valve train 21 should decrease from one revolution of the cam 11 to the next, the plunger spring 51 moves the plunger member 32 and the socket member 33 outwardly to expand the pressure chamber 60 and enable a relatively large amount of replacement fluid to flow into the pressure chamber to thereby effect an increase in the axial length of the hydraulic valve lifter 10. In this manner, the check valve assembly 47 cooperates with the plunger member 32 and the socket member 33 to maintain a predetermined relationship between the cam 9, rocker arm 17 and the valve 20 even though the dimensions of valve train 21 change during operation of the engine.

During high speed operations of the engine, the valve closing spring 19 tends to surge when the valve train reaches critical speeds where the natural frequency of the spring is a low harmonic of the valve train operating frequency. When excessive surging of the spring 19 occurs the effective force of the spring 19 is reduced and momentary separation of the valve train occurs. The temporary slack in the valve train eflects an increase in size of the pressure chamber 60 due to the force of the plunger spring 51 located therein.

In known valve lifters, the increase in size of the pressure chamber and the axial length of the hydraulic valve lifter is greater than that necessary to maintain a desired predetermined relationship between the cam, the rocker arm and the valve. This results because the valve lifter tends to expand to take up the temporary slack which is caused by the temporary condition of surging of the entire valve train. When the surging of the valve train continues, a condition known as pump-up of the hydraulic valve lifter usually results. This pump-up condition results trom the inability of known check valves to control the flow of lubricant into the pressure chamber when the surging condition occurs. The pump-up condition causes the valve 20 to be held in a partially open condition due to excessive axial extension of the hydraulic valve lifter. When the valve 20 is held in a partial open condition due to a pumping-up of the hydraulic litter, the flow of gases from the combustion chamber of the engine is unproperly controlled and a decrease in operatlng efliciency of the engine results.

In accordance with the present invention, the check valve assembly 47 provides means for metering the flow of lubricant to the pressure chamber 60' upon the occurrence of surging of the valve train 21. The means for metering the flow of lubricant to the pressure chamber 60 include the check valve member 52, the check valve spring 50 and the opening 64 located in the lower portion of the check valve retainer member 48. It should be realized that the flow of lubricant through the fluid passageway 46 into the pressure chamber 60 must flow around the check valve member 52, through the coils of the check valve spring 50 and through the opening 64 in order to enter the pressure chamber 60. When the check valve ball member 52 reaches its second limit position, wherein the spring is fully compressed and limits further movement of the ball 52 as shown in FIG. 3, the cross-sectional area of the flow path through which the lubricant must flow into the pressure chamber 60 is substantially reduced so that only a minimal or restricted flow of lubricant flows into the pressure chamber 60. The restricted lubricant flow to the pressure chamber results due to the fact that compression of the spring reduces the area between the coils of the spring which thereby reduces the cross-sectional area of the flow path of the lubricant to the pressure chamber 60.

At critical engine operating speeds, when the valve train 21 tends to surge excessively the acceleration of the lifter 10 tends to be rapid and in opposite directions. When a fast upward acceleration of the lifter 10 occurs during surge of the valve train 21, the inertia of the valve member 52 causes the valve member 52 to move downwardly to its second limit position to compress the spring 50 as shown in FIG. 3 to thereby restrict the flow of lubricant to the pressure chamber. A sudden reversal in the lifter 10 causes the ball member 52 to move upwardly to its first limit position and seat on the valve seat 46a thus, blocking the flow of fluid into the pressure chamber 60. Therefore, it should be realized that a rapid upward movement of the lifter 10 causes the check valve ball 52 to move from its first limit position, shown in FIG. 2, in which it blocks the flow of fluid to the pressure chamber 60, through a position in which the fluid flow path to the pressure chamber 60 has a maximum efiective cross-sectional area through the coils of the spring 50 to the second limit position shown in FIG. 3 in which the fluid flow path to the pressure chamber 60 has a predetermined efl'ective cross-sectional area which is defined as the space between the compressed coils of spring 50. The predetermined eflective cross-sectional area when the spring 50 is compressed is smaller than the maximum eifective cross-sectional area which occurs when the ball 52 is in a position intermediate the position shown in FIG. 2 and FIG. 3.

When the valve train 21 starts to surge, it should be realized that the ball member '52 will move rapidly between the position shown in FIGS. 2 and 3 and, therefore, the flow into the pressure chamber 60 will be restricted. This restricted flow of fluid caused by the compression of the valve spring 50 acts as a pump-up deterrent and prevents a large flow of fluid into the pressure chamber 60 when surging of the valve train occurs. The restricted flow of the fluid into the pressure chamber allows the plunger member 32 to move upwardly slowly and does not allow sufiicient fluid to flow into the pressure chamber 60 to pick any lash that is introduced into the valve train during erratic valve train motions. The restricted flow of fluid into the pressure chamber provides for slow upward movement of the plunger member to its normal operating condition by controlling the fluid flow into the pressure chamber so as to create a vacuum in the pressure chamber which opposes rapid upward movement of the plunger member. While the vacuum does not prohibit the upward movement of the plunger member, it does slow the upward movement substantially so as to eliminate problems of pump-up" during erratic valve train motions.

When the lifter 10 is allowed to sit in an engine that is not running for a period of time, the fluid in the pressure chamber 60 tends to leak out through the space 62 between the body member 30 and the plunger 32. This causes the pressure chamber 60 to be substantially void of lubricating fluid at cold engine starts, and the valve member 52 moves to its second limit position under the influence of the fluid pressure in the pressure chamber 60 when the engine is started. The absence of a substantial amount of lubricant in the pressure chamber 60 when the engine is started causes the lifter 10 to have a reduced axial extent. This reduced axial extent introduces lash in the valve train which causes noisy operation of the valve train. Therefore, to prevent noisy operation of the valve train, it is desirable to allow the lubricant to flow into the pressure chamber 60 to thereby increase the axial extent of the litter and take up the lash in the valve train. Providing lubricant flow to the pressure chamber 60 is complicated at cold engine starts due to the fact that lubricating fluids generally have a relatively high viscosity at cold temperatures and, therefore, flow slowly to the pressure chamber when the engine is cold.

The present invention prevents noise at cold engine starts by providing for a restricted flow of lubricant into the pressure chamber 60 when the check valve ball 52 compresses the spring 50. If the check valve ball 50 were to prevent the flow of lubricant into the pressure chamber 60 at cold engine start conditions, a much longer period of time would elapse before the chamber 60' could expand by the flow of lubricant therein. As a result, a longer period of time would elapse before lash in the valve train would be taken up. Thus, the provision of a check valve means which allows a restricted flow of lubricant into the pressure chamber 60, rather than completely blocking the flow of lubricant into the chamber 60 when the check valve member 52 compresses the spring 50, eliminates lash in the valve train and a noisy valve train upon cold start ups. This results in the advantage over the prior art valve lifters, such as illustrated in the Donnelly et al. patent, in that an effective anti-pump check valve is provided which does not result in noise in the valve train during cold engine start up conditions. Thus, it should be apparent that the restricted flow of fluid to the pressure chamber is great enough to eliminate lash in the valve train at cold engine starts and yet is small enough to prevent pumpup of the lifter during surging of the engine valve train.

For the purposes of providing a more complete under standing of the invention, several modified forms of the invention are shown in FIGS. 4-9. In these modified forms or embodiments of the invention numerals like those used on conjunction with the embodiment of FIGS. l-3 have been used to designate like parts.

The check valve assembly 75, illustrated in FIG. 4, provides for a restricted flow of lubricant to the chamber 60. The check valve assembly 75 includes a check valve ball 52 and a check valve retainer member 70. The ball 52 is biased by the check valve spring '50 to a first limit position in which it seats against the check valve seat 46a to prevent fiow of lubricant to the pressure chamber 60. Downward movement of the check valve ball 52 against the bias of the check valve spring 50 causes the check valve ball 52 to engage with the sides of the check valve retainer 7 0.

The retainer member 70 has substantially a conical configuration and has flutes 74 disposed in the side thereof. The flutes 74, more fully illustrated in FIG. 5, have a cross-sectional area which provides for a predetermined restricted flow of lubricant to the pressure chamber 70 when the ball 52 moves to its second limit position in which it engages with the sides of the retainer 70. It should be realized that when the ball reaches its lowermost position, as illustrated by the dotted lines in FIG. 4, the flow of lubricant to the pressure chamber 60 will not be entirely blocked. Rather, the lubricating fluid will flow around the ball member 52 through the flutes 74 and through the openings 72 disposed in the side of the retainer member 70. Thus, it should be apparent that the check valve assembly 75 illustrated in FIG. 4 functions to provide a restricted lubricant flow to the pressure chamher 60 when the check valve ball 52 moves to its limit position in which it engages with the retainer member 70. This restricted flow of fluid prevents pump-up of the lifter and also prevents noisy operation of the valve train by minimizing lash therein in substantially the same manner as the check valve means 47 illustrated in FIG. 2. While the flutes are illustrated at the limit position of the check valve member, it should be apparent that the same results could be obtained by providing the flutes at the top of the retainer where it butts against the plunger member. This construction would also provide a restricted fluid flow to the pressure chamber and prevent pump-up of the lifter.

The check valve assembly illustrated in FIG. 6 functions in a manner similar to the check valve 47 illustrated in FIG. 2 with the exception that a fiat check valve 82 is provided rather than a check valve ball. It should be apparent in this embodiment that the flow of lubricant into the pressure chamber 60 flows from the passageway 46 around the flat check valve member 82 through the spring member 50 and through the orifice 64 located in the bottom of the retainer 48. Thus, when the member 82 compresses the spring 50, the flow of lubricant to the pressure chamber '60 will be restricted as the crosssectional area of the flow path will be decreased and pump-up of the lifter and lash in the valve train will be prevented as discussed hereinabove.

Another embodiment of the check valve assembly for a hydraulic valve lifter is illustrated in FIG. 7. In this embodiment, the check valve means includes a check valve retainer 92, a check valve spring 50, a check valve ball member 52, and a pair of orifices 94 located in the bottom of the retainer 90. Movement of the ball member 52 in a downwardly direction causes compression of the spring 50 and the spring meters the lubricant into the pressure chamber 60, as described hereinabove in connection with the. embodiment of 'FIG. 2.

The orifices 94 are disposed on a projection or stop member 96 located on the bottom of the retainer member 92. The projection 96 provides a positive stop for the check valve ball 52 when the ball moves to its second limit position. In other words, downward movement of the check valve ball member 52 will effect engagement of the ball member 52 with the projection 96 to thereby prevent further downward movement of the ball member 52. The ball member 52 will engage with the stop member 96 when the spring is compressed so as to meter the flow of lubricant through the orifices 94 to the pressure chamber 60. The provision of the positive stop 96 prevents damage to the check valve spring 50 that might occur if the spring member is compressed more than necessary. It should be realized, however, that the check valve means 90 functions in substantially the same manner as the check valve means 47 illustrated in FIG. 2 in that compression of the spring 50 provides for the restricted flow of lubricant into the pressure chamber 60 when the check valve ball 52 reaches its lowermost or second limit position, and that the flows are such as to prevent pump-up during engine valve train surging and yet minimize noise during cold engine starts.

The embodiment of the invention illustrated in 'FIG. 8 includes a check valve ball member 52 and check valve spring 50 located in a check valve retainer 98. The. check valve retainer 98 has an orifice 100 located in the side thereof which provides for flow of fluid to the pressure chamber 60. In this embodiment when the check valve member 52 moves downwardly, the flow of the lubricant through the orifice 100 results in movement of the ball member '52 against the side of the retainer 98, as illustrated by the dotted line, to thereby restrict the flow of lubricant into the pressure chamber 60 through the orifice 100. It should be apparent that during the surging of the engine valve train, the ball 52 cooperates with the orifice 100 to provide a restricted flow of lubricant to the pressure chamber '60. Moreover, at cold engine start conditions the ball 52 will also move sidewardly to provide for a restricted flow of lubricant to the pressure chamber 60. Thus, the embodiment of FIG. 8 functions in essentially the same manner as the previous embodiments by providing a restricted flow of lubricant to the pressure chamber 60 to prevent pump-up of the lifter during engine valve train surge and minimize lash in the valve train at cold engine starts.

Another embodiment of the present invention, illustrated in FIGS. 9 and 10, includes the check valve assembly 110. The check valve assembly 110 includes a check valve retainer 112 which supports the check valve spring 50 and the ball member 52. The check valve retainer 112 has a pair of orifices 116 through which lubricant flows to the pressure chamber 60. The retainer 112 also has an upper relatively large diameter portion in which the ball member 52 is located, and a relatively small diameter lower portion connected with the upper portion to provide a shoulder 114 which has a substantially circular configuration and a diameter less than that of the ball member 52.

When the ball member 52 moves in a downwardly direction to the position shown in FIG. 10, the outer surface of the ball 52 cooperates with the shoulder 114 to restrict the flow of lubricant through the orifices 116 to thereby control the flow of lubricant to the pressure chamber 60. Movement of the ball 52 downwardly restricts the cross-sectional area of the flow path to the pressure chamber 60 which includes the space between the shoulder 114 and the ball member 52. Thus, downward movement of the ball member 52 restricts the flow of lubricant to the pressure chamber as described hereinabove.

In this embodiment, it has been discovered that the flow dynamics result in forces acting on the ball 52 so that the ball does not seat on the shoulder 114 but rather moves downwardly to a position where the ball and the shoulder 114 assume a spaced apart relationship which provides for a restricted flow of lubricant to the pressure chamber 60. It should be noted that a modification of this embodiment could be constructed so that the ball would seat on the shoulder 114. In the modified form where the ball 52 seats on the shoulder 114, the shoulder 114 could have a number of flutes disposed therein similar to the flutes of the embodiment of FIG. 4 or the flutes could be disposed on the top of the retainer where it butts against the plunger member. The flutes would provide for a restricted flow to the pressure chamber when the ball engaged with the shoulder 114.

Since, due to the particular construction of the check valve of the embodiment shown in FIG. 9, the check valve ball member 52 will not engage the shoulder 114, a flow passageway will be continually maintained therebetween. As a result, a restricted flow of fluid to the chamber 60 will occur, even though the ball is in its limit position, illustrated in FIG. 10'. This restricted flow of cfluid, as in the other embodiments described above, is slow enough to prevent pump-up of the valve lifter during valve train surging but, yet, is large enough to minimize lash in the valve train during cold engine starts and thereby prevent noise resulting therefrom.

.It has been observed that the plunger member 32 will return at a very slow rate to its normal operating position during operation of the valve lifter. This should be compared with the normal rate of return of valve lifters which is substantially instantaneous. In the valve lifter construction of FIG. 9, the plunger member 32 will return to its normal operating position in the lifter at about one-fourth the rate at which the plungers of the prior art will return to the positions.

From the foregoing, it should be apparent that a new and improved hydraulic valve lifter has been provided which prevents pump-up of the lifter under the influence of surging of the engine valve train and also which minimizes lash in the valve train during cold engine starts. The valve lifter includes a body member and a plunger member which cooperate to define a pressure chamber therebetween. A check valve assembly is provided to restrict the flow of lubricant into the pressure chamber. The check valve assembly includes a valve member which is movable from a first limit position blocking the flow of lubricant into the pressure chamber to a second limit position in which the valve member restricts the flow of fluid to the pressure chamber. This restricted flow of fluid to the pressure chamber prevents pump-up of the valve lifter during surging of the engine valve spring. Moreover, the anti-pump up means provided in the present invention also provides for quiet operation of the valve train during cold engine starts by providing a restricted flow of lubricant to the pressure chamber when the valve member is in its second limit position to thereby minimize lash in the valve train. This provides a distinct advantage over known anti-pump up devices which prevent lubricant ifiow to the pressure chamber at cold engine starts and thereby cause excessive lash in the valve train.

Having described my invention, I claim:

1. A hydraulic valve lifter for use in a valve train of an engine valve of an internal combustion engine and which engine valve is biased closed by an engine valve spring which surges at critical operating speeds and eflects surging of the valve train, said valve lifter comprising a body member, a plunger member located in said body member, said body member and said plunger member defining a chamber therebetween, said plunger member defining a fluid reservoir, a fluid passageway means providing for fluid cflow between said reservoir and said chamber, said means for preventing pump-up of the lifter during the surging of the engine valve train, said means including a spherical valve member for controlling the flow of fluid to said chamber and movable from a first limit position in which said valve member blocks the passageway through a position in which the passage has a maximum eflective cross-sectional area to a second limit position in which the passageway has a predetermined crosssectional area smaller than said maximum effective crosssectional area, a spring member biasing said valve member to said first limit position, said valve member being movable to said second limit position against the force of said spring member during engine valve train surging, and a retainer member, having a substantially frustoconical configuration and including fluted passages disposed thereon, for containing said valve member and said spring, said valve member engaging said retainer member in the second limit position and said fluted passages allowing fluid flow into said fluid chamber when said valve member is in said second limit position.

References Cited UNITED STATES PATENTS 2,220,336 11/ 1940 Johnson ct -al. 12390 2,542,036 2/1951 Knaggs 123 2,681,644 6/1954 Purchas, Jr. et a1. l2390 2,752,901 7/1956 Bergmann 12390 2,797,673 7/1957 Black l2390 3,304,925 2/ 1967 Rhoads l2390 3,406,668 10/ 1968. Donnelly et al. 123-90 AL LAWRENCE SMITH, Primary Examiner