US2815012A

US2815012A - Automatic lash adjuster

Info

Publication number: US2815012A
Application number: US505628A
Authority: US
Inventors: Sampietro Achilles Charles
Original assignee: Thompson Products Inc
Current assignee: Northrop Grumman Space and Mission Systems Corp
Priority date: 1955-05-03
Filing date: 1955-05-03
Publication date: 1957-12-03
Anticipated expiration: 1974-12-03

Description

Dec. 3, 1957 A. c. SAMPIETRO 2,815,012

AUTOMATIC LASH ADJUSTER Filed May 5, 1955 United States Patent AUTOMATIC LASH ADJUSTER Achilles Charles Sampietro, Ann Arbor, Mich., assignor to Thompson Products, Inc., Cleveland, Ohio, a corporation of Ohio Application May 3, 1955, Serial No. 505,628

4 Claims. (Cl. 123-90) The .present invention relates to a lash adjuster for automatically taking up any slack in valve operating and linkage mechanism and more particularly to one that does not add to the reciprocating weight or inertia of the valve linkage.

The present invention, like that of my copending application Serial No. 440,896, filed July 2, 1954, now Patent No. 2,771,866, November 27, 1956, pertains to a hydraulic automatic valve lash adjuster but specifically contemplates one wherein the adjuster depends from a fixed reaction bar above the valve rocker arm.

An object of this invention is to provide a lash adjuster wherein a fixed reaction bar is not only employed as the means for attaching the lash adjusting mechanism to the engine but is also an oil gallery for supplying fluid under pressure to a piston universally socketed in the rocker arm.

Another object of this invention is to provide a lash adjuster which makes use of a simple cup shaped piston on the closed end of which the rocker arm is universally journaled and the open end of which is slidably received in, a bore in the reaction bar through which controlled fluid oil under pressure is fed to the interior of the piston.

Another object of this invention is to provide a lash adjuster of the foregoing character which is fundamentally simple, self. adjusting and which by virtue of the fact that the spherical fulcrum is devoid of holes, bolts and the like enables longer life as well as minimizes the likelihood of oil leakage.

In accordance with the general features of this invention, there is provided in a valve gear including a push rod, a rocker arm actuated by the rod, and a spring loaded engine valve including a stem actuated by the arm, the improvement of a rocker arm mounting and lash adjusting mechanism comprising a cupped hollow piston having a lower closed end on which the rocker arm is universally journaled, a reaction bar in which another and open end of the piston is slidably disposed, conduit means discharging into the interior of the hollow piston at the open end of the piston received in the bar, and check valve means associated with the reaction bar andprojecting toward the closed end of the hollow piston in spaced relationto the piston wall for controlling the flow of fluid from the conduit into the interior of the closed end' of the piston.

Other features of the invention relate to the provision ofa. check valve in the form of a ball loosely carried in a cage, and responsiveto the fluid pressure in the piston; to the carrying of the check valve on a barrier separated from-the piston by a spring urging the piston toward the rocker arm; and tothe disposing of the ball cage in detachable snap-on engagement with the barrier about a passageway through the, barrier.

Other objects and features of this invention will more fully appear from the following detailed description, taken in connection with the accompanying drawings 2,815,012 Patented Dec. 3, 1957 Ice which illustrate a single embodiment thereof, and in which:

Figure 1 is a fragmentary, transverse cross-sectional view, with parts in elevation, of a valve in head internal combustion engine equipped with an automatic lash adjuster according to this invention;

Figure 2 is a plan view of the rocker arm with the piston omitted; and

Figure 3 is a fragmentary, sectional view corresponding to a portion of Fig. 1, but showing the ball valve seated on the end of the passageway in the barrier for closing off the flow of fluid into the piston when the slack between the engine valve and the rocker arm has been taken up.

As shown on the drawings:

The reference character 10 designates generally an internal combustion engine which includes the customary cylinder block 11 and a cylinder head 12. A guide 13 is provided in the head 12 for slidably receiving therein the stem 14 of a conventional engine poppet valve 15. This valve on its lower end has a head 16 cooperable with a seat 17 in the engine head 12 to control the control flow of gases between port 18 and combustion chamber 19 in a manner well known in this art.

The upper end of the valve stem 14 has grooves 20 therearound and the conventional split 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 the locks 21 and a valve spring 23 surrounding the valve stem has one end bottomed in the retainer 22 and the other end bottomed on the shoulder 24 of the engine head 12 surrounding the guide 13. This valve spring 23 is compressed to hold the valve head seated.

Cooperable with the end of the valve stem 14 in the usual way is a stamped sheet metal rocker arm 25 which has a depressed fragmental spherical socket portion .26 cooperable with my novel lash mechanism to be hereinafter 1 described.

The rocker arm 25, as shown in Fig. 2, is bounded by an upturned peripheral flange 28 to have a generally bowl-shaped interior 29.

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 conventional engine push rod 32. The push rod end 31 can rock in the socket and an oil aperture 33 is provided through the socket 30 to lubricate the end 31 of the push rod.

On the opposite sideof the socket 26, the bowl-shaped portion 29 of the rocker 25 is depressed at 34 to provide a rounded exterior for rocking on the end 35 of the valve stem 14.

Cooperable with the socket 26 of the rocker arm 25 is a lash adjusting piston 36 extending upwardly from the rocker arm. This piston is cup shaped and formed hollow so as to provide a rounded lower end 37 mounted in the socket 26 and bearing against the top surface of the rocker arm 25 so that the rocker arm is universally socketed on end 37. The wall 38 of the hollow piston 36 extends upwardly from the rocker arm into a hole or bore 39 formed in a fixed reaction bar 40. This reaction bar 40 may be of any suitable metal construction such as a casting bolted to the cylinder head or the like.

It will be observed from Fig. 1 that the open end 41 of the piston 36 is slidaibly received in plunger-like manner within the bore 39 but only extends part way into the bore. Positioned in and transversely of the :bore 39 is a barrier or valve carrying member 42 which is located in close proximity to but spaced from the upper end 41 of the piston 36. The barrier member 42 has a transverse hole 43, the ends of which are in communication with an-roil line or conduit 44 formed in the bar 40.

In other words, the bar 40 provides an oil gallery for the piston. Obviously, the oil line 44 may be connected to the oil pressure system of the engine in any suitable manner (not shown).

The trans-verse barrier 42 may be retained in position by any suitable means so that its transverse passageway 43 is in communication with the oil line 44. In the illustrated embodiment, the barrier member is held up against a snap ring 45 in the upper end of the bore 39 by means of a spring 47. This spring 47 is disposed between the underside of the barrier 42 and a stop or ring 48 on the interior wall of the hollow piston 36. Thus, the piston 36 is spring urged downwardly toward the rocker arm 25 and into socketed cooperation therewith, even when no oil pressure is being developed in oil line 44. 'The spring force applied is such as not to interfere with the spring seating of valve 15.

I shall now proceed to describe in detail the novel check valve means of my invention, which is carried by the barrier 42 and which is designated generally by the reference character 50.

Referring now more particularly to 'Figs. 1 and 3, it will be perceived that the barrier or member 42 has a vertical passageway 51 at right angles through, to and extending in the direction of the axi of the plunger-like piston 36. This passageway not only extends through a portion of the body of member 42 but also through an integral downwardly depending boss or nubbin 52. One end of the passageway communicates at right angles with the horizontall passageway 43 and the other and lower end discharges into the hollow piston 36. Detachably snapped onto the boss 52 is a cup shaped metallic cage 53 which has in its dome portion a plurality of apertures 54. This cage 53 and the eooperable boss 52 constitute cooperating parts of the ball check Valve assembly 50.

Loosely disposed in the bottom of the cage 53 is a ball 55 which when in its lowermost position is slightly spaced from the discharge end of fluid or oil passageway 51 connected with transverse passageway 43 and the oil line 44.

It will be noted that the cup shaped :cage 53 has a beaded edge 56 adapted to yieldably snap into a groove 57 in the internal surface of boss or nubbin 52.

Now assuming that there is play or lack between the engine valve linkage and the rocker arm 25, which for example may be as much as several thousandths of an inch, the engine oil under pressure flowing in oil line 44 passes through

passageways

43 and 51 and apertures 54 into the interior of the hollow piston 36. This fluid is thereby enabled to apply hydraulic pressure against the inner surface of the closed end 37 of the piston socketed in rocker arm 25. The ensuing pressure takes up the slack and yet is not suflicient, as is common in lash adjusters, to interfere with the spring loaded engine valve 15. Thus, the slack is not only taken up but in addition the rocker arm is held properly mounted in cooperation with the engine valve stem 14 and the push rod 32 with hydraulically cushioned pressure.

"Upon an action to open the engine valve 16, upward movement of the piston 36 occurs resulting in a reverse flow of fluid from chamber 38 to passage 51 thereby seating the valve ball '54 as shown in Fig. 3 and closing ofi flow through passage 51. Valve ball 54 thus controls fluid flow through passage 51 and also enables a fluid lock when slack is taken up.

It will be noted that the cage 53 and its ball 55 are readily attachable to or detachable from the boss 52.

In the foregoing ilas'h adjuster, it will be appreciated that the relative sizes of the piston 36 and the bore 39 are such as to permit a small leakage of oil and so as to allow for the expansion of various parts [due to heat. In other Words, in the device suitable clearance is priovided to permit leaking off of the oil if over expansion should occur due to thermal discontinuities of operation.

from the above descriptions it is now clear that this invention provides an automatic valve lash adjuster which does not add to the inertia or reciprocating weight of the valve gear and which serves the dual function of not only taking up lash in the valve gear but also providing a universal pivot for the rocker arm of the valve gear.

It will be understood that modifications and variations may be eifected without departing from the scope of the novel concepts of the present invention.

I claim as my invention:

1. In a valve gear including a push rod, a rocker arm actuated by the rod, and a spring loaded engine valve including a stem actuated by the arm, the improvement of a rocker arm mounting and lash adjusting mechanism comprising a hollow plunger-like piston having a rounded closed end socketed in and bearing against said rocker arm for urging said arm toward and into engagement with said push rod and the stem of said valve, a reaction bar including a fluid conduit in communication with a bore longitudinally aligned with said piston, said piston having its other end formed open and slidably received in said bore, a transverse barrier in said bore between said piston open end and said fluid conduit and having a fluid passageway between said conduit and the interior of said piston, and a check valve controlling the flow of fluid from said passageway into said piston for efiecting a fluid lock when slack between said engine valve and rocker arm is taken up, said check valve including a ball opposite the discharge end of said passageway and an apertured ball cage carried by said barrier around said discharge end and in which said ball is loosely disposed, the apertures in said cage communicating with the interior of said piston for delivery of fluid thereto and being in proximity to the ball for enabling the fluid to seat the ball against said discharge end of the passageway to close ofl the same when said valve slack has been taken up.

2. In a valve gear including a push rod, a rocker arm actuated by the rod, and a spring loaded engine valve including a stem actuated by the arm, the improvement of a rocker arm mounting and lash adjusting mechanism comprising a hollow plunger-like piston having a rounded closed end socketed in and bearing against said rocker arm for urging said arm toward and into engagement with said push rod and the stem of said valve, a reaction bar including a fluid conduit in communication with a bore longitudinally aligned with said piston, said piston having its other end formed open and slidably received in said bore, a transverse barrier in said bore between said piston open end and said fluid conduit and having a fluid passageway between said conduit and the interior of said piston, and a check valve controlling the flow of fluid from said passageway into said piston for effecting a fluid lock when slack between said engine valve and rocker arm is taken up, said check valve including a ball opposite the discharge end of said passageway and an apertured ball cage carried by said barrier around said discharge end and in which said ball is loosely dis-- posed, the apertures in said cage communicating with the interior of said piston for delivery of fluid thereto and being in proximity to the ball for enabling the fluid to seat the ball against said discharge end of the passageway to close oif the same when said valve slack has been taken up, said cage being in detachable snap-on engagement with said barrier about said passageway.

3. In a valve gear including a push rod, rocker arm actuated by the rod, and a spring loaded engine valve including a stern actuated by the arm, the improvement of a rocker arm mounting and lash adjusting mechanism comprising a hollow piston having a cylindrical oil chamber opening from the upper end and having a closed lower end on which the rocker arm is pivotally journaled, a fixed reaction bar with an oil conduit and having a. communicating cylindrical bore formed therein in which the open end of the piston is slidably disposed, a barrier member in the cylindrical bore of the reaction bar having a passageway communicating between the interior of said hollow piston and the oil conduit in the reaction bar, check valve means associated with the barrier member for preventing the flow of fluid from the interior of the closed end of the piston into the conduit and permitting the flow of fluid into the piston, a locking ring engaged in a groove spaced from the bottom of the cylindrical oil chamber of the hollow piston to form a spring reaction seat, and a coil compression spring seated on said locking ring and extending between the ring and the barrier member whereby the spring extends less than the depth of the oil chamber and urges the piston and barrier member apart.

4. In a valve gear including a push rod, a rocker arm actuated by the rod, and a spring loaded engine valve including a stem actuated by the arm, the improvement of a rocker arm mounting and lash adjusting mechanism comprising a piston having a lower bearing end on which the rocker arm is pivotally mounted and an upper end against which oil pressure acts to urge the bearing end against the rocker arm, a reaction bar having an oil passageway therein and a smooth cylindrical bore extending downwardly through the bar intersecting the oil passageway and in which said piston is slidably mounted, a barrier member slidably inserted into said cylindrical bore in the reaction bar above the piston and forming an oil pressure chamber between the barrier member and the upper end of said piston, said barrier member having a passageway communicating between said oil passageway and said oil pressure chamber, a check valve carried by the barrier member preventing the flow of oil from the pressure chamber through said passageway, a retainer projecting into the cylindrical bore above the barrier member preventing it from sliding upwardly and a spring between the piston and barrier member holding the barrier member against said retainer.

References Cited in the file of this patent UNITED STATES PATENTS 1,265,735 Brush May 14, 1918 2,075,597 Zahodiakin Mar. 30, 1937 2,718,219 Chayne et a1. Sept. 20, 1955 FOREIGN PATENTS 436,744 Great Britain Oct. 17, 1935