US3838669A

US3838669A - Hydraulic lash adjuster

Info

Publication number: US3838669A
Application number: US00280063A
Authority: US
Inventors: M Dadd
Original assignee: Johnson Products Inc
Current assignee: Sealed Power Technologies LP; Kodiak Partners Corp; Johnson Products Inc
Priority date: 1972-08-11
Filing date: 1972-08-11
Publication date: 1974-10-01
Anticipated expiration: 1991-10-01
Also published as: JPS5531288B2; FR2196003A5; JPS4945209A; CA995531A; BR7305625D0; AU5691373A; IT992580B; GB1379878A; DE2337111A1; AU472964B2

Abstract

In a hydraulic lash adjuster having a plunger which adjusts for taking up slack in the valve train, a cup element is positioned in the plunger cavity for reducing the pressure in the adjuster reservoir. A restricted passageway is formed by the cup wall directing flow from the inlet both into the reservoir and up toward a lip of the cup thereby reducing the reservoir pressure relative to the inlet pressure. The cup lip includes a groove forming a restricted meter passageway between the closure element opening and the cup lip periphery.

Description

United States Patent 1191 1111 3,838,669

Dadd Oct. 1, 1974 [54] HYDRAULIC LASH ADJUSTER 3,630,179 12/1971 Dadd 123 9035 [75] Inventor: Morris V. Dadd, Muskegon, Mich.

Przmary Exammer-Charles J. Myhre [73] Assignee: Johnson Products Inc., Muskegon, Assistant E i r R H Lazarus Mich- Attorney, Agent, or FirmPrice, Heneveld, Huizenga 22] Filed: Aug. 11, 1972 & Cooper [21] Appl. No.: 280,063 [57] ABSTRACT In a hydraulic lash adjuster having a plunger which ad- [52] US. Cl. .123/9035, l84/6.9 justs for taking up slack in the valve train, a cup [51] Int. Cl. FOlm 9/10 ment is positioned in the plunger cavity for reducing [58] Fleld of Search 123/9035 90-43; 84/69 the pressure in the adjuster reservoir. A restricted passageway is formed by the cup wall directing flow from [56] References (mad the inlet both into the reservoir and up toward a lip of UNITED STATES PATENTS the cup thereby reducing the reservoir pressure rela- 2,964,027 12/1960 Dadd 123/9035 tive to the inlet Pressure The p p includes 11 3,153,404 10/1964 Van Scooten groove forming a restricted meter passageway be- 3,267,918 8/1966 Ayres tween the closure element opening and the cup lip pe- 3,448,730 6/1969 Abell, Jr. riph ry 3,476,093 ll/l969 Line 3,598,095 8/1971 Ayres 123/9035 12 CIaImS, 5 Drawmg gu HYDRAULIC LASH ADJUSTER BACKGROUND OF THE INVENTION This invention relates to hydraulic lash adjusters, and more particularly to a novel lash adjuster which features an oil pressure reduction means that also meters the flow of lubricating oil through the adjuster.

Present high speed engines are beginning to use overhead camshaft engine designs to reduce the weight of reciprocation. This permits a higher speed operation while maintaining full control of the valve train operation. The reduction in reciprocating weight results in the load on the lash adjuster being considerably lighter when compared to a standard push rod type seat. Consequently it is desirable to reduce the oil pressure supplied to the lash adjuster in order to reduce the pumpup effect. There is also a need for a simpler and more economical means to provide a positive rate of oil flow through the adjuster to lubricate the rocker arm socket which is in receipt of the upper end of the lash adjuster. Thus, it is desirable to provide an economical means for metering the flow of lubricating oil in addition to reducing the oil pressure in the lash adjuster itself.

SUMMARY OF THE INVENTION A conventional lash adjuster includes a body with a reciprocating plunger movable in the body. The plunger has a central cavity portion defining an oil reservoir and inlet ports throughthe body and plunger to supply oil to the reservoir. The upper end of the plunger is closed by a closure element which in the overhead arrangement includes a fulcrum ball seated in the socket formed in the rocker arm. In a tappet utilizing a push rod, the closure element defines a push rod seating means. The closure element includes a central passageway to permit the injection of lubricating oil from the reservoir to the rocker arm.

In accordance with the invention, means are provided in the plunger cavity to form a restricted passageway at the inlet port to direct the flow of oil through the inlet port both into the reservoir and up toward the closure element. This reduces the reservoir pressure relative to the inlet pressure. The lower reservoir pressure allows the desired higher speed operation in the engine.

In a narrower aspect, a cup-shaped element having a lip extending radially from its open end is positioned in the cavity adjacent the inlet port. The cup wall diameter is less than the inner diameter of the plunger cavity at the inlet port to form the restricted passageway. The cup is positioned by an interior shoulder which holds the cup lip. The reservoir pressure however acts on the bottom of the cup to urge the cup off the shoulder against the closure element thereby permitting the flow of oil around the cup lip. The lip includes a groove means forming a restricted oil flow passageway to the central opening of the closure element from metering the rate of lubricating oil flow to the rocker arm socket.

The reduction in reservoir pressure relative the adjuster inlet pressure in accordance with the invention provides a unique relatively inexpensive construction for reducing the pump-up effect. In addition, a positive metering of the oil flow is achieved with the same element.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic representation partially in cross-section of an overhead cam valve train having a lash adjuster according to the invention;

FIG. 2 is an enlarged cross-sectional view of the lash adjuster shown in FIG. 1;

FIG. 3 is a plan view of the cup shown in FIG. 4;

FIG. 4 is a fragmentary cross-sectional view in elevation of the metering cup provided by the invention; and

FIG. 5 is an enlarged cross-sectional view similar to FIG. 2 of an alternative embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENT Briefly, a preferred application of the invention relates to usage in an overhead lash adjuster utilizing a movable closure element engageable directly with the rocker arm. However, the concepts are equally adapted in a tappet construction utilizing a closure element having a push rod seat engageable with a hollow push rod anchored to the rocker arm. Both applications are discussed separately below.

OVERHEAD LASH ADJUSTER Referring now to the drawings in detail, FIGS. 1 and 2, show a valve 2 having a spring 4 and retainer 6 actuated by rocker 8 through a camshaft l0 and cam 12. The rocker arm 8 pivots about a socket 14 on lash adjuster 16. The lash adjuster, which automatically adjusts for lash, contains a body 18 with a plunger 20 having an internal cavity 22 which opens into a bottom compression chamber through check-valve plate 24. The upper open end of plunger 20 is closed by a closure element 26 which along with plunger 20 is biased in the upward position against the closed socket 14 of rocker arm 8 through a spring 28. A spring 30 biases valve plate 24 against the bottom of plunger 20. A valve retainer 32, which holds the check-valve assembly in place, is held against the bottom of plunger 20 by spring 28.

Lubricating oil enters cavity 22 through ports-34 and 36. As is conventional in hydraulic valve lifter assemblies, the oil passes through cavity 22 through the bottom portion of plunger 20 into the bottom compression chamber. Cavity 22 forms an oil reservoir. The reciprocal motion of plunger 20 in body 18 is limited at the lower extremity by a shoulder 38 and at the upper extremity by a retainer ring 40 which clips over the upper end of body 18 and is engageable in the extreme position by a shoulder 42 of closure element 26.

Referring now in greater detail to FIG. 2, the counter-bore of plunger 20 which defines cavity 22 includes an internal shoulder 44 which acts as a stop for metering cup 46. Cup 46 includes a bottom wall 48 and an annular sidewall 50. The upper end of sidewall 50 is formed into an outwardly projecting annular lip 52 which under certain conditions will seat on shoulder 44, the shoulder acting as a stop for further downward.

movement of cup 46. The outer diameter of lip 52 is less than that of the plunger wall to permit oil to flow around the lip as required. Shoulder 44 is positioned slightly above inlet port 36 so that when cup 46 is positioned within cavity 22, wall 50 extends over inlet port 36. The outer diameter of wall 50 is less than the inner diameter of cavity 22 at inlet port 36 so that a restricted passageway 54 is formed at inlet port 36. The significance or restricted passageway 54 will be described hereinafter.

The closure element 26 includes a main body portion 56, the lower end of which is receivable in plunger cavity 22. Closure element 26 includes a central opening 58 which extends longitudinally through closure element 26. The cross-sectional configuration of opening 58 is enlarged at the lower end of closure element 26 with its axial depth corresponding generally to that portion of closure element 26 which is telescoped within plunger 20. The lower end of closure element 26, which is open, forms an annular seat 60. Shoulder 42 is positioned so that there is a minimum spacing between the lower end 60 of closure element 26 and internal shoulder 44 which exceeds the thickness of lip 52. When cavity 22 is filled with oil, the oil pressure therein will push metering cup 46 up off shoulder 44 into engagement with the lower end or seat 60 of closure element 26. This configuration permits the flow of oil beneath and around lip 52 over shoulder 44.

A groove 53 is formed in the lip portion 52 of cup 46 to permit flow communication from the inlet 36 or reservoir 22 into the central opening 58 of closure element 26. By careful selection of the cross-sectional flow area of groove 53, the rate of flow through the adjuster can be metered. It will be appreciated that a groove could be formed in the lower end of the closure element as an alternative to that in the lip portion.

The upper end 62 of closure element 26 has a spherical configuration to form a fulcrum ball receivable in socket 14 (FIG. 1) of rocker arm 8. The fulcrum ball 62 is retained in socket 14 by a spring clip 64, the lower end of which snaps into an annular retaining groove 66 formed in body 56 of closure element 26. As oil is metered through central opening 58 of closure element 26, it will be directed onto the surfaces of engagement between fulcrum ball 62 and socket 14. An oil bleed port 68 is provided through rocker arm 8 and aligned with central opening 58 to facilitate the passage of lubricating oil through the lash adjuster.

OPERATION During the engine operation, lubrication oil is brought into the plunger cavity 22 through

ports

34 and 46. Since the outer diameter of wall 50 of metering cup 46 is less than the inner diameter of cavity 22 at the inlet side of port 36, the oil pressure will cause the cup to position itself away from the inlet in abutment with the inner wall of the plunger opposite inlet 36. This will define a restricted passageway 54 which extends both downwardly into the plunger cavity or tappet reservoir 22 and upwardly toward cup lip 52. Since the oil pressure in cavity 22 acting against the bottom wall 48 of cup 46 will cause the cup to move up into abutment with the bottom surface or seat 60 of closure element 26, oil flow is permitted up restricted passageway 54 around lip 52. By diverting some of the oil flowing in through port 36 in this fashion, the oil pressure in cavity 22 relative to the inlet

oil pressure throughports

34 and 36 will be less. This lower pressure allows the desired higher speed operation in the engine. Once the oil flow reaches the intermediate area between shoulder 44 and closure element 26, further flow is permitted through groove 53 formed in lip 52 into the central opening 58 of te closure element. The flow is then directed through central opening 58 into the rocker arm socket 14. By careful selection of the cross-sectional area of groove 53, the flow of oil through central opening 58 can be metered. Preferably, the cross-sectional area of restricted passageway 54 is greater than groove 53 to assure a constant meter rate. It will be appreciated that restricted passageway 54 could perform the metering function. However, the length of this passageway. may vary and hence. the metering rate would vary.

TAPPET WITH PUSH ROD Referring now in detail to FIG. 5, a tappet 16a is illustrated which is in many respects similar or identical to portions of tappet 16 described in detail above. Therefore, corresponding elements referred to hereinafter which are similar to those described above will be referred to with the same numeral and the suffix a added.

Tappet 16a is designed for use in an internal combustion engine utilizing a push rod 69 cooperatively associated between a push rod seat 70 movable within tappet body 18a and the rocker arm of the valve train (not shown).

The tappet 16a operates essentially the same as tappet 16 and hence the structural recitation will not be repeated. The reference numerals however are provided to illustrate corresponding elements. Essentially. the only real distinction between the alternative embodiment shown in FIG. 5 from that shown in FIG. 1 is the change in the configuration of the closure element. Element 72 in FIG. 5 includes a push rod seat surface 70 formed in the upper end thereof. A centrally located axially extending opening 58a communicates from seat 70 through the closure element below which is positioned metering cup 46a identical to cup 46. Cup 46a rests on an internally machined shoulder 440. C10- sure element 72 includes an annular shoulder 76 extending beyond the outer wall of the closure element for abutment against the upper end of plunger 20a. By selecting the proper axial thickness of closure element 72, the lower surface of the closure element is spaced above shoulder 44a so that axial movement of cup 4611 is permitted in accordance with the description concerning the embodiment of FIG. 1.

The operation and function of the tappet illustrated in FIG. 5 should thus be obvious in view of the discussion relevant to FIG. 1. Oil flowing into the tappet body through opening 34 flows through the plunger wall through inlet opening 36a. The flow is directed through opening 36a simultaneously down into the reservoir 22a and up around lip 52a in view of the outer diameter of cup 460 being less than the diameter of the plunger bore. The reservoir pressure will urge cup 46a up against the lower surface of closure element 72 and oil flowing up around lip 52a is introducd into opening 58a in closure element 72 through a groove 53a formed in the lip of cup 46a. By proper selection of the crosssectional area of groove 530, the oil flowing through the closure element can be properly metered. As a result of .the simultaneous flow of oil coming through inlet opening 36a both into the reservoir 22a and up around lip 52a of cup 460, the reservoir pressure is reduced relative to the inlet pressure.

In accordance with the invention, a very simple and yet positive means is provided for reducing the oil pressure in the reservoir to permit higher speed operation of the engine. In addition, the very means which provides this result also performs the metering rate for the lubricating oil passing through the lash adjuster. The simplicity of the metering cup described not only makes it economically inexpensive to produce, but also provides positive assembly of the adjuster. That is, there is little or no chance of misassembling the tappet.

Although two embodiments have been shown and described in detail, it will be obvious to those having ordinary skill in this art that the details of construction of these particular embodiments may be modified in a great many ways without departing from the unique concepts presented. It is, therefore, intended that the invention is limited only by the scope of the appended claims rather than by particular details of construction shown, except as specifically stated in the claims.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. In a hydraulic lash adjuster for an internal combustion engine having a body; a plunger reciprocal within said body, said plunger having a central cavity forming an oil reservoir; a lubricating oil inlet means communicating with said central cavity of said plunger; a closure element forming the upper outer portion of said plunger; and lubricating passage means extending from the central cavity of said plunger through said closure element; the improvement comprising a cup means positionable in said plunger cavity beneath said closure element for reducing the pressure in said oil reservoir relative to the pressure at said oil inlet means, said cup means having a side wall, a bottom wall, and an open top, said top facing said closure element, said inlet means being'positioned intermediate said open top and bottom wall during operation of said adjuster, the side wall of said cup means forming a restricted passageway from said inlet means to said cavity and further forming a restricted passageway from said inlet means to said closure element such that the flow from said inlet means is diverted simultaneously into saidreservoir and closure element thereby reducing the oil pressure in said reservoir relative to said inlet means, said inlet means being comprised of a first opening through said body and a second opening through said plunger, said openings being in communication with each other, the wall of said plunger cavity having an inner shoulder formed therein above said second opening, said cup means having an outwardly projecting lip formed at its upper end, said lip being engageable on said shoulder whereby the wall of said cup is positioned adjacent said second opening, the diameter of said cup being less than said cavity wall to form said restricted passageway, and means comprising a longitudinal spacing between said shoulder and closure element greater than the thickness of said cup lip, the diameter of said lip being less than that of said cavity wall above said shoulder, the oil pressure in said reservoir urging said cup lip against said closure element whereby said lip is clear of said shoulder, said cup lip having a groove formed in the upper surface to form a passageway for oil flow from the outer surface of the lip to said central openi. The lash adjuster according to claim 1 wherein said groove with said closure element forms a restricted flow passageway which also meters the flow of oil to said closure element.

3. The lash adjuster according to claim 1 wherein said closure element includes a spherical head providing a pivot for a rocker arm, said spherical head being receivable in a rocker arm socket, and a body having a portion receivable in said plunger.

4. The lash adjuster according to claim 1 wherein said closure element is comprised of a push rod seat means formed in the upper end thereof.

5. A hydraulic lash adjuster having an internal cavity; an internal reservoir; oil inlet and outlet means; means communicating with said oil reservoir, inlet, and outlet means to permit flow through said adjuster while re ducing the reservoir pressure relative to the oil inlet pressure, said means comprising a cup-shaped element positioned in said cavity adjacent said inlet means, the wall of said cup-shaped element during operation of said adjuster defining a restricted passageway from said inlet means to said reservoir and outlet means whereby oil flowing through said inlet means is directed simultaneously to said reservoir and outlet means thereby causing the oil pressure in said reservoir to have a reduced pressure relative to the inlet pressure, the upper rim of said cup-shaped element having an outwardly projecting lip positioned intermediate said inlet and outlet means, said lip including a groove formed in the upper surface thereof, said groove with said outlet means forming a restricted passageway for oil flow to said outlet, said groove metering the rate of flow through said outlet.

6. In a hydraulic lash adjuster for an internal combustion engine having a body; a plunger reciprocal within said body, said plunger having a central cavity forming an oil reservoir; a lubricating oil inlet means communicating with said central cavity of said plunger; a closure element forming the upper outer portion of said plunger; and lubricating passage means extending from the central cavity of said plunger through said closure element; the improvement comprising means for reducing the pressure in said oil reservoir relative to the pressure at said oil inlet means, said means for reducing the pressure in said oil reservoir comprising a cup means positionable in said plunger cavity beneath said closure element, said means having a sidewall and an open top, said top facing said closure element, the sidewall of said cup means forming a restricted passageway from said inlet means to said cavity and further forming a restricted passageway from said inlet means to said closure element such that flow from said inlet means is movable simultaneously into said reservoir and closure element thereby reducing the oil pressure in said reservoir relative to said inlet means, said inlet means comprising a first opening through said body and a second opening through said plunger, said openings being in communication with each other, the wall of said plunger cavity having an inner shoulder formed therein above said second opening, said cup means having an outwardly projecting lip formed at its upper end, said lip being engageable on said shoulder whereby the wall of said cup is positioned adjacent said second opening, the diameter of said cup being less than said cavity wall to form said restricted passageway, said adjuster including a longitudinal spacing between said shoulder and closure element greater than the thickness of said cup lip, the diameter of said lip being less than that of said cavity wall above said shoulder, the oil pressure in said reservoir urging said cup againstsaid closure element whereby said lip is clear of said shoulder, said closure element includes a central opening therethrough, said cup means lip having at least one groove formed in the upper surface to form a restricted passageway for oil flow from the outer surface of said lip and closure element to said central opening, said groove metering the rate of flow through said central opening.

7. The lash adjuster according to claim wherein said closure element is comprised of a push rod seat means formed in the upper end thereof.

8. In a hydraulic lash adjuster for an internal combustion engine having a body; a plunger reciprocal within said body, said plunger having a central cavity forming an oil reservoir; a lubricating oil inlet means communicating with said central cavity of said plunger; a closure element forming the upper outer portion of said plunger; and lubricating passage means extending from the central cavity of said plunger through said closure element; the improvement comprising: means for reducing the the pressure in said oil reservoir also metering the flow of oil to said closure element and comprising a cup means positionable in said plunger cavity beneath said closure element, said cup means having a sidewall and open top, said top facing said closure element, the upper margin of said sidewall having an outwardly projecting lip, said cup being urged by the oil within said reservoir against said closure element so that said lip abuts said closure element, said closure element having a central opening therethrough, said lip having at least one groove formed in the upper surface thereof to form a restricted passageway for oil flow from the outer surface of said lip to said central opening, said groove metering the rate of flow to said central opening.

9. The lash adjuster according to claim 8 wherein said cup diameter is less than the diameter of said'cavity, said wall of said cup forming a restricted passageway from said inlet means to said reservoir and closure element to reduce the oil pressure in said reservoir relative to said inlet means.

10. In a hydraulic lash adjuster for an internal combustion engine having a body; a plunger reciprocal within said body, said plunger having a central cavity forming an oil reservoir; a lubricating oil inlet means communicating with said central cavity of said plunger; a closure element forming the upper outer portion of said plunger; a lubricating passage means extending from the central cavity of said plunger through said closure element; the improvement comprising: cup means positionable in said plunger cavity beneath said closure element, said cup means having a sidewall and open top, said top facing said closure element. the upper margin of said sidewall having an outwardly projecting lip, said cup being urged by the oil within said reservoir against said closure element so that said lip abuts said closure element, said closure element having a central opening therethrough, said lip having at least one groove formed in the upper surface thereof to form a restricted passageway for oil flow from the outer surface of said lip to said central opening, said groove metering the rate of flow to said central opening.

11. The lash adjuster according to claim 1.0 wherein said closure element is comprised of a push rod seat means formed in the upper end thereof.

12. The lash adjuster according to claim 10! wherein said closure element includes a spherical head providing a pivot for a rocker arm, said spherical head being receivable in a rocker arm socket, and a body having a portion receivable in said plunger.

Claims

1. In a hydraulic lash adjuster for an internal combustion engine having a body; a plunger reciprocal within said body, said plunger having a central cavity forming an oil reservoir; a lubricating oil inlet means communicating with said central cavity of said plunger; a closure element forming the upper outer portion of said plunger; and lubricating passage means extending from the central cavity of said plunger through said closure element; the improvement comprising a cup means positionable in said plunger cavity beneath said closure elemEnt for reducing the pressure in said oil reservoir relative to the pressure at said oil inlet means, said cup means having a side wall, a bottom wall, and an open top, said top facing said closure element, said inlet means being positioned intermediate said open top and bottom wall during operation of said adjuster, the side wall of said cup means forming a restricted passageway from said inlet means to said cavity and further forming a restricted passageway from said inlet means to said closure element such that the flow from said inlet means is diverted simultaneously into said reservoir and closure element thereby reducing the oil pressure in said reservoir relative to said inlet means, said inlet means being comprised of a first opening through said body and a second opening through said plunger, said openings being in communication with each other, the wall of said plunger cavity having an inner shoulder formed therein above said second opening, said cup means having an outwardly projecting lip formed at its upper end, said lip being engageable on said shoulder whereby the wall of said cup is positioned adjacent said second opening, the diameter of said cup being less than said cavity wall to form said restricted passageway, and means comprising a longitudinal spacing between said shoulder and closure element greater than the thickness of said cup lip, the diameter of said lip being less than that of said cavity wall above said shoulder, the oil pressure in said reservoir urging said cup lip against said closure element whereby said lip is clear of said shoulder, said cup lip having a groove formed in the upper surface to form a passageway for oil flow from the outer surface of the lip to said central opening.

2. The lash adjuster according to claim 1 wherein said groove with said closure element forms a restricted flow passageway which also meters the flow of oil to said closure element.

5. A hydraulic lash adjuster having an internal cavity; an internal reservoir; oil inlet and outlet means; means communicating with said oil reservoir, inlet, and outlet means to permit flow through said adjuster while reducing the reservoir pressure relative to the oil inlet pressure, said means comprising a cup-shaped element positioned in said cavity adjacent said inlet means, the wall of said cup-shaped element during operation of said adjuster defining a restricted passageway from said inlet means to said reservoir and outlet means whereby oil flowing through said inlet means is directed simultaneously to said reservoir and outlet means thereby causing the oil pressure in said reservoir to have a reduced pressure relative to the inlet pressure, the upper rim of said cup-shaped element having an outwardly projecting lip positioned intermediate said inlet and outlet means, said lip including a groove formed in the upper surface thereof, said groove with said outlet means forming a restricted passageway for oil flow to said outlet, said groove metering the rate of flow through said outlet.

6. In a hydraulic lash adjuster for an internal combustion engine having a body; a plunger reciprocal within said body, said plunger having a central cavity forming an oil reservoir; a lubricating oil inlet means communicating with said central cavity of said plunger; a closure element forming the upper outer portion of said plunger; and lubricating passage means extending from the central cavity of said plunger through said closure element; the improvement comprising means for reducing the pressure in said oil reservoir relative to the pressure at said oil inlet means, said means for reducing the pressure in saId oil reservoir comprising a cup means positionable in said plunger cavity beneath said closure element, said means having a sidewall and an open top, said top facing said closure element, the sidewall of said cup means forming a restricted passageway from said inlet means to said cavity and further forming a restricted passageway from said inlet means to said closure element such that flow from said inlet means is movable simultaneously into said reservoir and closure element thereby reducing the oil pressure in said reservoir relative to said inlet means, said inlet means comprising a first opening through said body and a second opening through said plunger, said openings being in communication with each other, the wall of said plunger cavity having an inner shoulder formed therein above said second opening, said cup means having an outwardly projecting lip formed at its upper end, said lip being engageable on said shoulder whereby the wall of said cup is positioned adjacent said second opening, the diameter of said cup being less than said cavity wall to form said restricted passageway, said adjuster including a longitudinal spacing between said shoulder and closure element greater than the thickness of said cup lip, the diameter of said lip being less than that of said cavity wall above said shoulder, the oil pressure in said reservoir urging said cup against said closure element whereby said lip is clear of said shoulder, said closure element includes a central opening therethrough, said cup means lip having at least one groove formed in the upper surface to form a restricted passageway for oil flow from the outer surface of said lip and closure element to said central opening, said groove metering the rate of flow through said central opening.

7. The lash adjuster according to claim 5 wherein said closure element is comprised of a push rod seat means formed in the upper end thereof.

9. The lash adjuster according to claim 8 wherein said cup diameter is less than the diameter of said cavity, said wall of said cup forming a restricted passageway from said inlet means to said reservoir and closure element to reduce the oil pressure in said reservoir relative to said inlet means.

10. In a hydraulic lash adjuster for an internal combustion engine having a body; a plunger reciprocal within said body, said plunger having a central cavity forming an oil reservoir; a lubricating oil inlet means communicating with said central cavity of said plunger; a closure element forming the upper outer portion of said plunger; a lubricating passage means extending from the central cavity of said plunger through said closure element; the improvement comprising: cup means positionable in said plunger cavity beneath said closure element, said cup means having a sIdewall and open top, said top facing said closure element, the upper margin of said sidewall having an outwardly projecting lip, said cup being urged by the oil within said reservoir against said closure element so that said lip abuts said closure element, said closure element having a central opening therethrough, said lip having at least one groove formed in the upper surface thereof to form a restricted passageway for oil flow from the outer surface of said lip to said central opening, said groove metering the rate of flow to said central opening.

11. The lash adjuster according to claim 10 wherein said closure element is comprised of a push rod seat means formed in the upper end thereof.

12. The lash adjuster according to claim 10 wherein said closure element includes a spherical head providing a pivot for a rocker arm, said spherical head being receivable in a rocker arm socket, and a body having a portion receivable in said plunger.