US2863430A

US2863430A - Lash adjuster

Info

Publication number: US2863430A
Application number: US576339A
Authority: US
Inventors: Sampietro Achilles Charles
Original assignee: Thompson Products Inc
Current assignee: Northrop Grumman Space and Mission Systems Corp
Priority date: 1956-04-05
Filing date: 1956-04-05
Publication date: 1958-12-09
Anticipated expiration: 1975-12-09

Description

A. C. SAMPIETRO Dec. 9, 1958 LASH ADJUSTER Filed April 5, 1956 4O 4G INVENTOR.

ACHILLES CHARLES SAMPIETRO A RNCYS I agar LASH ADJUSTER Achilles Charles Sampietro, Detroit, Mich., assignor to Thompson Products, Inc., Cleveland, @hio, a corporation of Ohio Application April 5, 1956, Serial No. 576,339

17 Claims. (Cl. 123-90) under the pressure of the oil from the engine to hold the rocker arm against the valve stem and push rod and take up the play which occurs in the linkage.

The present invention contemplates a lightweight stamped, pressed, brazed, or otherwise fabricated metal rocker arm having a fragmental spherical depressed portion and receiving a mounting stud or post anchored in the engine head. A hearing member with a hemispherical end is slid'able on the post or stud to seat in the depressed portion of the rocker arm. The stud or post has an oil passage therethrough to which is connected a pipe leading from the oil pressure system of the engine. A conduit leads from the oil passageway through the post to an annular chamber in the base of the piston which is covered by an annular check valve preventing a backflow of oil from the pressure chamber. A weak spring holds the check valve in place permitting a flow of oil at low engine speeds and a support for the weak spring is held in place by a strong spring which permits movement of the support and the valve at oil pressures encountered at high engine speeds. The piston carries a circumferential seal preventing escape of oil between the piston wall and the bearingmember and a special oil leakage passageway through the piston permits a limited flow of oil from the pressure chamber to lubricate the parts of the engine valve linkage. Means are also provided to prevent accidental withdrawal of the piston from the bearing member.

An object of the invention is to provide an improved valve lash adjustment mechanism with an improved oil leakage path to lubricate the parts of the valve operating linkage.

Another object of the invention is to provide an 1mproved oil leakage arrangement for a valve lash adjuster in which the opportunities for clogging of the path are reduced and wherein the leakage arrangement is simpler and less expensive to construct.

Another object of the invention is to provide a valve lash adjustment mechanism with an improved check valve arrangement for preventing the backflow of oil from the pressure chamber of the lash adjuster.

A still further object of the invention is to provide a valve lash adjuster wherein the parts are simplified, more readily assembled and wherein the chance of accidental disassembly is reduced.

A still further object of the invention is to provide an improved oil conduit arrangement for distributing the oil to the pressure chamber of the valve lash adjustment mechanism. 7

A still further object of the invention is to provide an improved valve lash preventing mechanism which will States Patent 2 maintain a supply of oil in the mechanism in adequate quantities with varying engine speeds from cranking and idling to high running speeds.

Other objects, advantages and features of the present invention will become more apparent to those skilled in the art and to those who receive a full disclosure of the invention from the present specification, claims and drawings wherein like numbers are used to indicate like ele ments and in which:

Figure 1 is a vertical elevational view taken in section through the head of an internal combustion engine and illustrating a preferred embodiment of the present invention;

Figure 2 is an enlarged detailed view in vertical section illustrating the details of construction of the valve lash adjustment mechanism;

Figure 3 is a plan view of the lash adjustment mechanism;

Figure 4 is an enlarged fragmentary detail sectional view taken along line IV-IV of Fig. 2 with the outer cylinder wall removed; and

Figure 5 is a greatly enlarged detail vertical sectional view of a portion of Fig. 2.

While the figures of the drawings and the description of the specification illustrate the preferred embodiment of the invention as being incorporated in a mechanism for taking up the lash of a rocker arm for an internal combustion valve-in-head type of engine, it is to be expressly understood that the features, methods and objectives of the invention may be utilized and many of the advantages of the invention obtained in adaptations to other operating devices and the features and details shown and described herein are to be taken as illustrative only and not by way of limitation.

In the embodiment illustrated in Fig. 1, the internal combustion engine is shown generally at and includes a cylinder block 11 and a cylinder head 12. The head 12 has a guide 13 receiving in slidable relation therein the stem 14 of the poppet valve 15. The head 16 of the valve cooperates with the seat 17 in the engine head 12 to control the flow between the valve port 18 and the head 12 in the combustion chamber 19.

The upper end of the valve stem has grooves 20 thereon and the conventional split valve locks 21 have beads seated in these grooves. A valve spring retainer 22 is fixedly held on the upper end of the valve stem by locks 21 and a valve spring 23 surrounds the valve stem and has one end bottomed on a retainer 22 and the other end bottomed on a shoulder 24 of the engine head 12 surrounding the guide 13. The valve stem 14 is biased to hold the valve head 16 against seat 17.

A stamped sheet-metal rocker arm 25 has a depressed fragmental spherical socket portion 26 in the bottom thereof with an aperture 27 through the bottom of the socket. The rocker arm 25 is indicated in both Figs. 1 and 2 and is surrounded by an upturned peripheral flange 28 to have a generally bowl-shaped interior 29. At one end of the rocker arm and on one side of the socket 26, the bottom of the bowl 29 is raised to provide an inverted socket 30 for the rounded end 31 of a push rod 32. The push rod end 31 can rock in the socket 30 and an oil aperture 3.3 is provided through the socket to lubricate the end 31 of the push rod. On the opposite side of the socket 26 and on the opposite end of the rocker arm, the bowl-shaped bottom portion 29 of the rocker arm is depressed at 34 to provide a round exterior for engaging and rocking on the end 35 of the valve stem 14.

In accordance with this invention the rocker arm is mounted on the engine valve'head 12 by means of an automatic lash adjuster shown generally at 3.6. i The lash adjuster as shown in the detailed sectional view of Fig. 2 incorporates a vertical support or post 38 which has a smooth cylindrical outer surface and which is tapered at its lower end 40 for purposes of inserting into the opening 42 in the top of the engine head 12'or the part of the engine on which the lash adjuster is mounted. Extending axially through the center of the supporting post 38 is an axial bore 44 which is provided for the purpose of conducting oil upwardly to the lash adjustment mechanism. The bore 44 stops short of the lower end 40 in order that the oil will flow upwardly. To provide oil to the bore 44 an angular opening 46 extends radially from the outside of the post to communicate with the bore. The angular opening 46 communicates with a threaded hole 48 in the engine head 12 and in which a fitting 50 is threaded. The fitting 50 is provided for connecting an oil pipe or line 52 which leads from the pressurized oil system of the engine. The oil pipe 52- is connected to the fitting 58 by a male connector member 54 which secures the pipe to the fitting in a leakproof manner to channel the oil into the bore 44 of the supporting post 38.

The post is provided with a smooth cylindrical shank portion 56 which is in sliding engagement with the cylindrical bore 58 of the bearing member 60. In this manner the bearing member 60 is slidably mounted on the post for pivotally carrying the rocker arm 25. The smooth semi-spherical socket portion 26 of the rocker arm pivotally pushes up against the semi-spherical lower surface 62 of the bearing member for pivotal movement thereon. The aperture 27 in the bottom of the socket portion of the rocker arm is sufiiciently large to permit pivotal move ment of the rocker arm without interfering with the post 38. r

The bearing member has a vertically extending cylindrical wall 64 which is open at the upper end with a smooth inner cylinder surface 66 on the inside for slidably containing the piston 68.

The piston 68 is secured to the upper end of the supporting post 38 and for this purpose the post carries external threads 70 at its upper end to which the piston is threaded, the piston being fitted with an opening 72 extending upwardly from its lower end and containing threads for threading to the upper end of the post 38. An annular ring gasket 74 is provided on top of the post to prevent leakage of oil down into the threads 70. The upper end of the piston has a hexagonal head 77 for the purpose of applying a wrench to thread the piston firmly onto the top of the post 38.

Thus the piston is slidably located within the inner cylinder wall 66 of the bearing member 60. The lower hollow portion of the bearing member forms a pressure chamber 76 which is closed by the piston. The pressure chamber as defined within the hollow bearing member 60 between the inner walls of the bearing member and the post 38' contains oil under pressure as pumped therein by the oil pressure system of the engine and the pressurized oil forces the bearing -member 60 downwardly relative to the support 38 to push the rocker arm of the engine valve linkage down firmly against its valve stem and push rod to take up any lash in the linkage and prevent wear and excess noise which result when lash is present.

To seal the pressure chamber and prevent oil leakdown between the shank 56 of the post 38 and the inner bore 58 of the bearing member, the bearing member is provided with an inner annular groove 78. In this groove and tightly surrounding the shank 58 of the post 38 is an O-ring 80. The O-ring forms a tight seal between the bearing member and the post and prevents oil from leaking down past the post and escaping from the pressure chamber 76.

Oil is prevented from leaking upwardly out of the pressure chamber 76 and between the piston 68 and cylinder wall 66 by another O-ring 82. This O-ring is seated in an annular groove 84 extending completely around theout'er surface of the piston 68. Thus the O-ring 82 in the piston and the O-ring 80 between the bearing member and the post 38 permit a greater manufacturing tolerance between the mating parts since a close fit is not necessary to prevent leakage of oil and loss of pressure from the pressure chamber 76. This of course reduces the cost of manufacture and of assembly of the mating parts.

It is necessary however to obtain a controlled leakage of oil from the lash adjuster assembly in order to provide lubrication to the valve linkage, such as at the mating surfaces between the bearing member 60 and the rocker arm 25 and the surfaces between the rocker arm and push rod. 'If the leakage or leakdown of oil is permitted to take place between the operating surfaces, it is necessary that the manufacturing tolerances of the mating surfaces be accurate in order that an adequate leakdown is present and yet to avoid an excessive leakdown which would reduce the operating pressure in the pressure chamber 76 and permit too much oil to flow over the engine valve linkage. With the present arrangement a leakage passageway of a definite cross sectional area is so that the oil leaks upwardly from the pressure chamber 76 between the outer wall 90 of the piston and the inner wall '66 of the cylinder to pass upwardly through the leakage passageway. If the

holes

88 and 86 were to be drilled to the exact dimension that would provide the proper leakage, it would be necessary that they would be extremely small which would make them diificult to drill and which would make them susceptible to clogging by foreign material or by oil sludge.

In order to simplify the drilling operation and reduce the opportunity for clogging, the hole 88 is intentionally drilled oversize. Within the hole 88 as is shown in the details of Fig. 4 and in Fig. 2, is positioned a free floating cylindrically shaped pin 92. This pin fills up a portion of the cross sectional area of the hole 88 and the differences between the area of the hole 88 and the pin 92 define the area or the size of the passageway through which the oil may flow. The pin 92 is an inexpensive element and can be easily assembled by merely dropping into the hole during assembly before sliding the piston 68 in place within the cylinder wall 64 of the bearingmember.

Although the metering area or the flow area is usually determined by the difference in areas between the pin 92 and the hole 88, this metering area will approach the area between the piston 68 and the cylinder wall 64. It will be recognized that if this latter area between the piston and cylinder wall becomes smaller than the metering area between the pin 92 and hole 88 then said latter area will naturally become the metering area. Thus if it were necessary to drill the hole 88 sufficiently small so that it in itself would be the metering duct, it would have to be extremely small in diameter. With the use of the pin 92 the hole 88 can be of a substantial size and yet have the flow area accurately controlled by inserting the proper size pin 92.

The bore hole 44 within the post 38 is continued a short distance up into the piston by the tapered hole 94.

A conduit 96 extending angularly downwardly from the annularly around the annular face is a groove 100 as is sho in the detail view of Fig. 5. This groove serves It is to be noted that the hori-' as a distribution area conducting the oil completely around the piston to" be fed into the pressure chamber 76.

For sealing the groove and preventing a backfiow of oil from the pressure chamber 76, a check valve is provided shown in the form of an annular valve ring 102 which is seated against the groove 100. The annular ring 102 is slightly larger than the extension 104 from the lower surface 98 of the piston and this extension 104 maintains the valve ring 102 in its proper position relative to the groove'100.

For purposes of holding the valve ring 102 in place in order that it may act as a check valve and yet permit the flow of oil from the groove into the pressure chamber 76, the ring is heldih place a weak Wave spring 106. The wave spring is supported in place by an annular support ring 108. The support ring is held upwardly in its supporting" position by a coil compression spring 110 which pushes the support ring 108 firmly against the lower surface of ashoulder 112 which is formed in the extension of the piston.

With the construction shown the oil pressures that are encountered atslow speeds of the engine such as cranking speed and idling speed will push the valve member 102 away from the groove 100 to permit a flow of oil down into the pressure chamber. The valve ring can only drop as far as it can compress the wave spring 106 and this distance is limited by the support ring 108. The small amount of opening permitted by the valve ring 102 against the wave spring 106, however, is sufficient to permit an adequate flow of oil since theperiod of time that the valve will be open at the slow speeds is longer than at higher engine speeds.

Athigher engine speeds only a small openingtime of the check valve 102 is available and therefore a greater quantity of oil must flow past the valve. In order to permit this increased rate of oil flow past the valve, the valve 102 must be open a larger distance and to permit this the spring 110 'will be compressed at the oil pressures that are encountered at high engine speeds. Thus the strong spring 110 will be compressed to open the valve a considerable distance at high oil pressures and high engine speeds and the wave spring 106 will alone be compressed at low pressures and at low engine speeds The strong spring 1 13) is located within the oil pressure chamber 76 and bottoms on the floor 114 of the pressure chamber.

In order that the piston 68 is not accidentally withdrawn from thecylindrical wall 64 of the bearing member or that the bearing member is not slid downwardly too far on the support post 38 so as to lose the cylindrical pin 92 which restricts the flow of oil, a stop is utilized to prevent the piston from leaving its position within the bearing member. To accomplish this end the wall 64 of the bearing member is provided with four laterally extending openings hear the top edge of the wall, the openings being shown at 114, 116, 118 and 120. The openings 114 and 11 6 lie along the same axis and the

openings

118 and 120 lie along the same axis, both axes being parallelto each other. A wire retainer 122 is then looped and projected through the holes and twisted together at its free ends 124 to hold it in place. This may be done if desired during assembly of the valve lash adjuster away from the engine so that parts may be readily handled without becoming disassembled and the assembled unit then inserted in place on the engine head by the post 38 being forcibly projected into the opening 42 in th'e'engine head by a press fit.

Thus it will be seen that I have provided an improved valve lash adjuster which meets the objectives hereinbefo're set forth. The mechanism permits a controlled leakdown of oil to lubricate the operating parts with a simple structure which feeds a metered amount of oil but does not require extremely small openings which aresnsceaabie to clogging.

The mechanism provides a simple and improved flow of oil to the pressure chamber within the bearing member and a simplified valve arrangement is used to prevent the backflow of oil and also to feed oil to the pressure chamber at all engine speeds. The mechanism uses parts which are inexpensive, easy to assemble and is capable of long periods of operation without excessive wear and without need of adjustment.

1 have, in the drawings and specifications, presented a detailed disclosure of the preferred embodiment of my invention, but it is to be understood that I do not intend to limit the invention to the specific form disclosed but intend to cover all modifications, changes and alternative constructions and methods falling within the scope of the principles taught by my invention.

1 claim as my invention:

1. A valve lash adjuster for a valve linkage including a rocker arm for operating a valve for an engine having a pressurized oil system, the lash adjuster comprising a supporting post adapted to be mounted on the engine and having an axially extending oil bore through said post, means connecting the oil bore to the pressurized oil system of the engine, a bearing member pivotally carrying the valve rocker arm and having a bore for slidably fitting the bearing member on the post, said bearing member having a cylindricallyhollow interior axially parallel with the post and defining an oil pressure chamber between the post and hollow interior, a piston slidably mounted within the cylindrically hollow bearing member interior and secured to the post to close the oil pressure chamber, an oil conduit communicating between the axial bore of the post and the pressure chamber, an oil seal between the outer wall of the piston and the inner cylindrical wall of the bearingmember, and an oil passageway extending from the outer wall of the piston between the oil seal and the pressure chamber to the piston surface at the other side of the oil seal to permit leakage of oil past the seal to lubricate the operat ing parts of the valve linkage.

2. A valve lash adjuster for a valve linkage including a rocker arm for operating a valve for an engine having a pressurized oil system, the lash adjuster comprising a supporting post adapted to be mounted on the engine, a bearing member pivotally carrying the valve rocker arm and having a bore for slida'bly fitting the bearing member on the post, said bearing member having a cylindrically hollow interior extending axially parallel to the post and defining an oil pressure chamber between the post and hollow interior, a piston slidably mounted with in the cylindrically hollow bearing member interior and secured to the post to close the oil pressure chamber, an oil conduit communicating between the pressure system of the engine and the pressure chamber, an oil seal between the outer wall of the piston and the inner cylindrical wall of the bearing member, an oil conduit bored in. said piston and communicating between an inlet in the piston wall between the oil seal and pressure chamber and an outlet in the piston surface on the other side of said oil seal to permit leakage of oil past the seal to lubricate the operating parts of the valve linkage.

3. A valve lash adjuster for a valve linkage including a rocker arm for operating a valve for an engine having a pressurized oil system, the lash adjuster comprising a supporting post adapted to be mounted on the engine, a bearing member pivotally carrying the valve rocker arm and having a bore for slidably fitting the bearing member on the post, said bearing member having a cylindrically hollow interior extending axially parallel to the post and defining an oil pressure chamber between the post and hollow interior, a piston slidably mounted within the cylindrically hollow bearing member interior and secured to the post to close the oil pressure cham ber, an oil conduit communicating between the pressure system of the engine and the pressure chamber, an oil seal between the outer wall of the piston and the inner cylindrical wall of the bearing member, an oil passage 7 4 way extending from the outer wall of the piston between the oil'seal and the pressure chamber to the piston surface at the other side of the oil seal to permit leakage of oil past the seal to lubricate the operating parts of the valve linkage, and arestriction insaid passageway permitting the passageway to be larger with the oil leakage path equalling the difference in cross sectional areas between the restriction and the passageway.

4. A valve lash adjuster for a valve linkage including a rocker arm for operating a valve for an engine having a pressurized oil system, the lash adjuster comprising a supporting post adapted to be mounted on the engine and having an axially extending oil bore through said post, means connecting the oil bore to the pressurized oil system of the engine, a 'bearing member pivotally carryingthe valve rocker arm and having a bore for slidably fitting the bearing member on the post, said bearing member having a cylindrically hollow interior axially parallel with the post and defining an oil pressure chamber betwee'nthe post and hollow interior, a piston slidably mounted within the cylindrically hollow bearing member interior and secured tothe post to close the oil pressure chamber, anoil conduit communicating between theaxial bore of the post and the pressure chamber, an oil seal between the outer wall of the piston and the inner cylindrical wall of the bearing member, a horizontally bored oil passageway in said piston opening through the piston Wall between the oil seal and pressure chamber, a vertically bored oil passageway leading through the top of the piston and in communication with the horizontal passageway, and a cylindrical pin freely positioned in said horizontal passageway to reduce the oil leakage path through said horizontal passageway and permit boring a larger horizontal passageway to' prevent clogging.

5. A valve lash adjuster for a valve linkage including a rocker arm for operating a valve for an engine having a pressurized oil system, the lash adjuster comprising a supporting post adapted to be mounted on the engine and having an axially extending oil bore through said post, means connecting the oil bore to the pressurized oil system of the engine, a bearing member pivotally carrying the valve rocker arm and having a bore for slidably fitting the bearing member on the post, said bearing member having a cylindrically hollow interior axially parallel with the post and defining an oil pressure chamber between the post and hollow interior, a piston slidably mounted within the cylindrically hollow bearing member interior and secured to the post to close the oil pressure chamber, an oil conduit communicating between the axial bore of the post and the pressure chamber, an oil seal between the outer wall of the piston and the inner cylindrical wall of the bearing member, an oil leakage passageway communicating between the exterior of the lash adjuster and the pressurized oil within the lash adjuster to deliver a supply of oil to the valve linkage, and a pin freely positioned in said passageway and parallel thereto to reduce the cross sectional oil path through the passageway and permit a larger passageway and reduce the opportunity of stoppage.

6. A valve lash adjuster for supporting a pivotal rocker arm on an engine head provided with a pressurized oil system comprising a supporting post adapted to be mounted on the engine and having an axially extending oil bore through said post, an oil pipe connected to the pressurized oil system and to the post to communicate with said bore, a bearing member pivotally carrying the valve rocker arm and having a bore for slidably fitting the bearing member on the post, said bearing member having a cylindrically hollow interior axially parallel with the post and defining an oil pressure chamber between the post and hollow interior, a piston slidably mounted within the cylindrically hollow bearing member interior and secured to the post to close the oilpressure chamber, an oil conduit communicating between the axial bore of 8 the post and the pressure chamber, an oil seal between the outer wall of the piston and the inner cylindrical wall of the bearing member, and an oil passageway extending from the outer wall of the pistonbetween the oil seal and the pressure chamber to the piston surface at the other side of the oil seal to permit leakage of oil past the seal to lubricate the operating parts of the valve linkage.

7. A valve lash adjuster for supporting a pivotal rocker. arm on an engine head provided with a pressurized oil system comprising, a supporting post adapted to be mounted on the engine and having an axially extending oil bore through said post, means connecting the oil bore to the pressurized oil system of the engine, a bearing member pivotally carrying the valve rocker arm and having a bore for slidably fitting the bearing member on the post, said bearing member having a cylindrically hollow 7 interior axially parallel with the post and defining an oil pressure chamber between the post and hollow interior, a piston slidably mounted within the cylindrically hollow bearing member interior and secured to the post to close the oil pressure chamber, an oil conduit through the piston opening on the lower face of the piston and connecting to the axial bore within the post, a check valve over the conduit opening to prevent a backfiow of oil from the pressure chamber, a spring for holding the check valve over the conduit opening, and a support for the spring held in operating position by the piston to maintain a constant pressure on the check valve.

8. A valve lash adjuster for supporting a pivotal rocker arm on an engine head provided with a pressurized oil system comprising, a supporting post adapted to be mounted on the engine and having an axially extending oil bore through said post, means connecting the oil bore to the pressurized oil system of the engine, a bearing member pivotally carrying the valve rocker arm and having a bore for slidably fitting the bearing member on the post, said bearing member having a cylindrically hollow interior axially parallel with the post and defining an oil pressure chamber between the post and hollow interior. a piston slidably mounted within the cylindrically hollow bearing member interior and secured to the post to close the oil pressure chamber, an oil conduit through the pis ton opening on the lower face of the piston and connecting to the axial bore within the post, an annular valve ring positioned over said conduit opening to prevent a backflow of oil from the pressure chamber, a first weak spring holding the ring in engagement with the lower face of the piston, an annular spring support carrying said first spring, a shoulder on said piston holding said spring support in spaced relationship to said valve ring, and a strong spring positioned within the pressure chamber and urging the spring support against said piston shoulder, said strong spring being compressible to admit a full flow of oil past the valve ring at oil pressures encountered at engine running speed.

9. A valve lash adjuster for supporting a pivotal rocker arm on an engine head provided with a pressurized oil system comprising, a supporting post adapted to be mounted on the engine and having an axially extending oil bore through said post, means connecting the oil bore to the pressurized oil system of the engine, a bearing member pivotally carrying the valve rocker arm and having a bore for slidably fitting the bearing member on the post, said bearing member having a cylindrically hollow interior axially parallel with the post and defining an oil pressure chamber between the post and hollow interior, a piston slidably mounted within the cylindrically hollow bearing member interior and secured to the post to close the oil pressure chamber, an oil distribution chamber at the base of the piston opening into the pressure chamber, an oil conduit through the piston opening into the chamher and connecting to the axial bore within the post, an annular valve ring over said open chamber preventing a backflow of oil from the pressure chamber, a weak spring holding the valve ring over the distribution chamher to permit the valve to open at pressures encountered at slow engine speeds, a support for the weak spring spaced from the valve, and a strong spring urging the support toward the valve and permitting movement of the valve and support with oil pressures encountered at high speeds.

10. A valve lash adjuster for supporting a pivotal rocker arm on an engine head provided with a pressurized oil system comprising, a supporting post adapted to be mounted on the engine and having an axially extending oil bore through said post, means connecting the oil bore to the pressurized oil system of the engine, a bearing member pivotally carrying the valve rocker arm and having a bore for slidably fitting the bearing member on the post, said bearing member having a cylindrieally hollow interior axially parallel with the post and defining an oil pressure chamber between the post and hollow interior, a piston slidably mounted within the cylindricaliy hollow bearing member interior and secured to the post to close the oil pressure chamber, an annular groove around the base of the piston forming an oil distribution chamber, an annular valve ring over said open chamber preventing a backflow of oil from the pressure chamber, a weak spring holding the valve ring over the distribution chamber to permit the valve to open at pressures encountered at slow engine speeds, a support for the weak spring spaced from the valve, and a strong spring urging the support toward the valve and permitting movement of the valve and support with oil pressures encountered at high speeds.

11. A valve lash adjuster for a valve linkage including a rocker arm for operating a valve for an engine having a pressurized oil system, the lash adjuster comprising a supporting post adapted to be mounted on the engine and having an axially extending oil bore through said post, means connecting the oil bore to the pressurized oil system of the engine, a bearing member pivotally carrying the valve rocker arm and having a bore for slidably fitting the bearing member on the post, said bearing member having a cylindrically hollow interior axially parallel with the post and defining an oil pressure chamber between the post and hollow interior, a piston slidably mounted within the cylindrically hollow bearing member interior and secured to the post to close the oil pressure chamber, and stop means connected to the bearing member and located in the path of the piston as it moves away from the bearing member preventing the piston from sliding out of the hollow interior of the bearing.

12. A valve lash adjuster for a valve linkage includ ing a rocker arm for operating a valve for an engine having a pressurized oil system, the lash adjuster comprising a supporting post adapted to be mounted on the engine and having an axially extending oil bore through said post, means connecting the oil bore to the pressurized oil system of the engine, a bearing member pivotally carrying the valve rocker arm and having a bore for slidably fitting the bearing member on the post, a cylindrical wall extending upwardly from the bearing member and defining an oil pressure chamber between the post and hollow interior and having lateral openings in the wall, a piston slidably mounted within the cylindrically hollow bearing member interior and secured to the post to close the oil pressure chamber, and a stop member extending laterally through said lateral openings and located in the path of the piston as it moves away from the bearing member preventing the piston from sliding out of the hollow interior of the bearing.

13. A valve lash adjuster for a valve linkage including a rocker arm for operating a valve for an engine, the lash adjuster comprising a housing member having an elongated bore, a piston member slidably mounted in said bore with a pressure chamber formed between said piston and said housing member within said bore, means supporting one of said members in a fixed operating position relative to the valve linkage, a bearing pivotally carry ing the valve rocker arm and secured to the other of said members to urge the rocker arm to non lash engagement with an engine valve, means for delivering pressurized fluid to said pressure chamber to urge said bearing against the rocker arm whereby lash is prevented, a fluid seal between the wall of the piston and said housing member,- and a fluid passagewayin one of said members located to receive fluid from the pressure chamber side of said seal and said pressure chamber and leading past said fluid seal whereby leakage of fluid will lubricate operating parts of the valve linkage.

14. A valve lash adjuster for a valve linkage including a rocker arm for operating a valve for an engine, the lash adjuster comprising a housing member having an elongated bore, a piston member slidably mounted in said bore with a pressure chamber formed between said piston and said housing member within said bore, means supporting one of said members in a fixed operating position relative to the valve linkage, a bearing pivotally carrying the valve rocker arm and secured to the other of said members to urge the rocker arm to non lash engagement with an engine valve, means for delivering pressurized fluid to said pressure chamber to urge said bearing against the rocker arm whereby lash is prevented, a fluid seal between the wall of the piston and said housing member, and a fluid passageway in one of said members opening between the sliding surfaces of said bore and said piston between said seal and said pressure chamber and by-passing said seal to channel fluid to lubricate operating parts of the valve linkage.

15. A valve lash adjuster for a valve linkage including a rocker arm for operating a valve for an engine, the lash adjuster comprising a housing member having an elongated bore, a piston member slidably mounted in said bore with a pressure chamber formed between said piston and said housing member within said bore, means supporting one of said members in a fixed operating position relative to the valve linkage, a bearing pivotally carrying the valve rocker arm and secured to the other of said members to urge the rocker arm to non lash engagement with an engine valve, 21 fluid passageway communicating with said pressure chamber, means conmeeting the oil pressure system of the engine to said passageway, a check valve preventing flow from the pressure chamber back into the passageway, means for permitting the oil pressure to open the valve a first amount during idling speeds of the engine, and means for preventing the oil pressure from opening the valve a greater amount during idling and permitting the valve to open a second larger amountduring engine running speeds.

16. A valve lash adjuster for a valve linkage including a rocker arm for operating a valve for an engine, the lash adjuster comprising a housing member having an elongated bore, a piston member slidably mounted in said bore with a pressure chamber formed between said piston and said housing member within said bore, means supporting one of said members in a fixed operating position relative to the valve linkage, a bearing pivotally carrying the valve rocker arm and secured to the other of said members to urge the rocker arm in non lash engagement with an engine valve, an oil passageway communicating with said pressure chamber, means connecting the oil pressure system of the engine to said passageway, a check valve preventing flow from the pressure chamber back into the passageway, 21 first weak biasing means engaging the check valve and permitting the valve to be opened a first amount during engine idling speed, and a second stronger spring normally spaced from the valve and stopping the valve during idling speeds but being overcome by oil pressure against the valve at running speeds to permit the valve to open a greater amount.

17. A valve lash adjuster for a valve linkage including a rocker arm for operating a valve for an engine, the

i1 lash adjuster comprising a housing member having an elongated bore, a piston member slidably mounted in said bore with a pressure chamber formed between said piston and said housing member within said bore, means supporting one of said members in a fixed operating position relative to the valve linkage, a bearing pivotally carrying the valve rocker arm and secured to the other of said members to urge the rocker arm to non lash engagement with an engine valve, means for delivering pressurized fluid to said pressure chamber to urge said bearing against the rocker arm whereby lash is prevented,

and stop means positioned in alignment with said bore and preventing the piston from sliding out of said bore whereby the piston and housing member may be handled.

as a unit without becoming disassembled.

References Cited inthe file of this patent UNITED STATES PATENTS 2,123,681 Willgoos July 12, 1938 10 2,718,219 Chayne et a1. Sept. 20, 1955 2,771,866 Sampietro Nov. 27, 1956