US3169515A

US3169515A - Fulcrum adjuster

Info

Publication number: US3169515A
Application number: US344751A
Authority: US
Inventors: Charles R Kilgore; James E Yingst
Original assignee: Thompson Ramo Wooldridge Inc
Current assignee: Northrop Grumman Space and Mission Systems Corp
Priority date: 1964-02-13
Filing date: 1964-02-13
Publication date: 1965-02-16
Anticipated expiration: 1982-02-16

Description

Feb- 16, 1955 c. R. KlLGoRE ETAL 3,159,515

FULCRUM ADJUSTER Filed Feb. 1s, 1964 @j ATTORNEYS United States Patent O 3,16%,515 FULCRUM ADSUS'EER Charles R. Kilgore, Wiiowiclr, and James E. Yingst, Russell riownship, Geauga County, Ghia, assigner-s to Thompson Ramo Wooldridge inc., Cleveland, Ohio, a corporation ot @hie Filed Feb. 13, 1964, Ser. No. 344,751 9 Claims. (Cl. 12S-90) The present invention relates to an improved fulcrum adjuster or lash adjuster for engine valve linkages. More specifically, the invention relates to anV improved oil operatedmechanism which prevents excessive and objec tionable lash in the operation of engine valves.

'lhe present invention provides a new and simplified fulcrum type hydraulic valve lash adjuster in which the number of machined component parts has been reduced substantially. What is more, the arrangement of elements is such that the fulcrurn adjuster can be made smaller, that is, with a smaller profile than has heretofore been the case. Not only are economies effected in the manufacture of the fulcrnm adjuster of the present invention, but from an operational standpoint the fulcrum adjuster of the present invention is more completely and more quickly responsive to changes in demand than other types of fulcrum adjusters previously suggested.

It is accordingly an object of the present invention to provide a zero lash adjuster having a minimum number of machined component parts. r

Another object of the present invention is to provide a fulcrum type lash adjuster in which the simple com- -bination of a bushing and a valve sleeve provide an internal valve of novel configuration.

Another object of the invention is to provide a valve lash adjuster having an internal valve element responsive to a hydraulic pressure differential, to viscous drag of the fluid passing through the leakdown annulus to the reservoir, to the fluid drag generated by the relative motionof the two elements comprising the leakdown annulus during the leakdown cycle, and to spring tension.

Another object of the invention is to provide an internal valve element for a fulcrum adjuster which is opened rapidly during the refill portion of the cycle by both a reversal in the pressure dierential and in the direction of action of the viscous drag caused by the relative motion of the elements defining the leakdown annulus.

Another object of the invention is to provide an adjuster which can be provided with a specific amount of built-in lash through the use of an element in the high pressure chamber which compresses uniformly immediately prior Vand immediately after valve opening to enable use of the adjuster with either lash or zero lash type cam shafts.

Another object of the invention is to provide a fulcrum adjuster having its own hydraulic system and means for maintaining a static internal pressure which insures rapid transporting of the hydraulic fluid from the reservoir to the pressure chamber.

Another object of the invention is to provide a selfcontained hydraulic valve lash adjuster which eliminates the necessity and expense of providing passages to transport the engine oil from the oil pump to each of the adjusters.

Another object of the invention is to provide a valve lash adjuster with a monocellular flexible element which has the characteristic of maintaining either a constant reservoir pressure in the mechanism or for providing a collapsible element of small volume to create built-in lash.

Another object of the invention is to provide a valve lelement between the reservoir and pressure chamber which is designed to open in proportion with the demand.

lg Patented Feb. 16, 1955 Other objects and features of the present invention will become apparent to those skilled in the art from the following description of the attached sheet of drawings which illustrate several embodiments of the invention.

FIGURE 1 is a vertical sectional view taken through a valve assembly employing a fulcrum adjuster of the present invention;

FIGURE 2 is a vertical sectional view through the fulcrum adjuster shown in FiGURE l; and Y FIGURE 3 is a vertical sectional view of a modified form of fulcrurn adjuster which is self-contained.

ln FlGURE l, reference numeral it) indicates generally an internal combustion engine including a cylinder block il having a cylinder head l2. A valve guide 13 is formed in the cylinder head 12'and receives a stem i4 of a poppet valve l5 in sliding relation therethrough. The valve i6 has the usual seating face 17 to control the flow of gases between a valve port i8 and a combustion chamber i9.

The upper end of the valve stem l. has grooves 21 formed therein, and conventional valve locks 22 are provided with beads which seat within the grooves 2l. A valve lock retainer 23 tightly engages the valve lock 22 and serves to bottom a valve spring 2d extending between the retainer 23 and a shoulder 26 `formed in the engine head l2.

The rocker arm may take the form of a stamped sheet metal arm 28 having a depressed fragmental spherical socket portion 29 with an aperture 3l through the bottom of the socket. The rocker arm 2S is provided with an upturned peripheral ange 32. At one end of the rocker arm 28 and at one side of the socket 29, the rocker arm is provided with an inverted socket 33 for the rounded end 34 of a pushrod 3S. On the opposite side of the socket 29, and on the opposite side of the rocker arm, the rocker arm is depressed as indicated at numeral 3i), to provide a rounded surface for engaging and rocking von the end of the valve stem 14. The fulcrum adjuster of the present invention has been identified generally in FGURE l at reference numeral 35. It is supported in its operating position to pivotally carry the rocker arm 28 on a post 37 which is threaded vor otherwise locked into a bore 33 communicating with an oil gallery passage 4l in the engine block. The passage 41 is supplied with pressurized oil from the oil pump of the engine.

The interior construction of the fulcrum adjuster 36 is shown in somewhat enlarged form in FIGURE 2. From this view it will be seen that the post 37 extends through an axial passage 42 formed in a barrel 43. The post 37 has a blind ended axial bore 44 which delivers oil to a plurality of radially extending cross ducts 45 which, in turn, deliver the oil to a distribution groove 47 formed in the outer periphery of the post 37. Y

A bushing 48 is mounted on the post 37 and has a plurality of inlet ports 49 4therein communicating with the distribution groove 47.

Loosely received within the interior of the barrel 43 is a valve sleeve 5l whose outer periphery is spaced suiiciently from the inner periphery of the barrel 43 to provide a leakdown annulus 52 therebetween.

The upper end of the bushing 4g contains a head portion S3, with a slight clearance space 54 being provided between it and the inner periphery 55 of the barrel 43, so that air may be vented from the assembly, as will be described in a succeeding portion of this description.

The valve sleeve 5l is formed internally with a frustoconical seating face 56 which confronts the peripheral edge of an enlarged annular shoulder 57 formed on the bushing 48. The edge of the shoulder 57 may thus be seated against the confronting seating surface 55 in substantially line contact thereby closing off a fluid reservoir .9 compartment 55 existing between the bushing lL-3, the barrel 43, and the valve sleeve Si. The seating surface 56 is urged into seating relation with the shoulder 57 by the action of a spring 6l. which is coniined between the lower end of the valve sleeve l and the interior of the barrel 43.

At the lower end of the bushing 43 there is provided a seal ring 62 covered by a washer 63. The seal element 62 is held in place against the bushing 4S and the barrel 43 by a'return spring ed located between the washer 63 and an annular shoulder 65 of lesser diameter than the annular shoulder 57 and axially spaced therefrom. The

spring urges the bushing'l against a lock ring 67 disposed in a suitable groove provided in the barrel 43 to contain the internal parts of the adjuster against the combined spring forces prior to installation in the engine. A nut 68 is threaded onto the end of the postv 37 to complete the assembly.

The structure shown in FIGURE 2 is intended for use in conjunction with oil circulating from the oil pump of the engine. The structure shown in FGURE 3 is selfcontained in that it has its own hydraulic system and a constant clearance element. The fulcrum adjuster of FlGURE 3 may include a barrel 71 of substantially the same configuration as the barrel ishown in FlGURE 2. A solid post 72 extends through an axial passageway 73 in the barrel 7l. A solid bushing 7d is mounted on the post 7.2 and has a headed portion 76 received within the interior of the barrel 71.

The modified form shown Yin FIGURE 3 also includes a valve sleeve 7? which cooperates with the internal periphery of the barrel 7l lto provide a leakdowrr annulus 79 therebetween. The value sleeve '78 also has a fiustoconical portion 81 which is arranged to seat the edge of an annular shoulder S2 formed in the bushing 74. A spring 83 disposed between the barrel 7l and the valve sleeve 73 urges the valve sleeve 73 into seated relation with the shoulder 82.

A lower seal element 34 is provided between the bushing 74 and the barrel 7l, and a second spring element 86 is confined between a washer 85 and an annular shoulder 87. It will thus be seen that the internal valve conguration of both embodiments of the invention are substantially identical.

The device shown in FIGURE 3 includes a combination upperseal and compressible energy storage device, in the form of a cellular seal 88 disposed about the upper end of the bushing '74. The cellular seal SS is composed Vof an elastic monocellular material whose. individual cells are iilled with a compressed gas. The seal 3S, the bushing 74, the valve sleeve 7S, and the wall of the barrel 71 all cooperate to define a reservoir chamber S9 for the hydraulic fluid contained within the fulcrum adjuster. The assembly is completed with a lock ring 9i and a nut 92 on the end of the post 7a. The compression chamber 90 of the fulcrurn adjuster may also contain a compressible element 93 in the form of a ball or the like designed to provide a specific amount of built-in lash, it desired.

The operation of the device in FIGURE 2 and its installation will now be described. After the adjuster is placed on the post 37, the hold-down nut 68 is positioned to cause the relative position ci the barrel i3 with respect to the'bushing 48 to be in mid-range. When the engine starts, engine oil is pumped through the gallery lil, up the axial passage i4 through the radial port to the distribution groove 47. From this groove, oil enters the reservoir chamber 5S through the radial passages r9 formed in the bushing 4S. As the reservoir lills, all the entrained air and the air being displaced by the oil escapes through the air vent 54. Once the air is vented, pressure in the reservoir builds up causing .he sleeve valve 5l. to open against the force of the biasing spring el. Gil then enters into the pressure chamber 70, forcing all of the air up and out through the air vent 5d. When filled, the adjuster is ready for normal operation.

ln the operation of the adjuster, as the rocker arm 23 is urged outward with respect to the cylinder head l2 by the pushrod 3S, the adjuster barrel 43 is urged upwardly, causing the pressure of the oil in the pressure chamber to increase. Simultaneously, the engine valve lo is forced open. During the duration of the engine valve opening, a small amount of oil is forced from the pressure chamber 7@ through the leakdown annulus 5.2. Once the engine valve le returns to its seat 17, the spring ed urges the barrel 43 downward with respect to the post 37 to take up all clearance in the valve train. Simultaneously, the pressure differential in the pressure chamber 7i? and the reservoir chamber 5S reverses. The valve sleeve 51 then opens, and a volume of oil suliicient to rer'ill the pressure chamber 76 is transferred from the reservoir 5S. The volume of refill oil as compared to the volume of discharge oil will vary as a function of engine operating conditions to compensate for changes in the valve train lengths.

There is very little relative movement between the valve sleeve 5l and theshoulder 57 durinfy steady opera*- ing conditions because the amount of lluid being circulated is extremely small. However, during engine start-up, the degree of valve sleeve opening is much greater for those adjusters that are collapsed during engine shutdown by engine valves that remained open. This variable opening feature reduces to a minimum the time required to till the pressure chamber under the conditions described.

T he modified form of the invention shown in FIGURE 3 overcomes problems that have been found to exist in some engines. For one, some engine oil pumps do not have suliicient capacity to maintain the minimum required reservoir pressure. ln addition, at high speeds, the oil in some engines become so whipped with microscopic air bubbles that they migrate into the pressure chamber before they have had time to rise and escape through the air vent. This produces an uncontrollable spongy condition and results in excessive valve trairrnoise. Furthermore, some engines lack oil passages extending from the oil pump to the location of the adjuster.

The fulcrum adjuster shown in FlGURE 3 operates in the following manner during one cycle of operation. As the barrel 71 is forced upwardly with respect to the bushing 74, relative motion between the two is resisted by the incompressible hydraulic fluid contained in the pressure chamber 99, and the force of the return spring 85. When the engine valve 16 is opened, a small percentage of hydraulic fluid is forced through the leakdown annulus 79 into the reservoir chamber S9. As the volume of fluid in the reservoir increases, the energy storing cellular seal 88 compresses, increasing the reservoir pressure slightly. Immediately upon seating of the engine valve 16, the return spring expands to take up any clearance that exists in the valve train. Simultaneously, the pressure differential in the adjuster reverses, so that the valve sleeve 78 leaves its seat, and a volume of fluid suilicient to lill the pressure chamber is transferred by the expanding cellular seal S3.

The cellular seal S8 is preloaded to maintain a certain minimum static pressure in the adjuster at all times. The lower seal element d4 can also be made of a monocellular material or a separate compressible element 93 can be included to provide a specific amount of lash in the valve train by compression immediately prior to valve opening.

From the foregoing, it will be understood that the fulcrum adjuster of the present invention provides a simpliiied but highly elective lash adjusting mechanism. Machined parts are reduced to an absolute minimum, without sacrifice in the eliiciency of operation. Response to demand conditions has improved, and the hydraulic duid is rapidly transferred to the high pressure chamber upon start-up from the collapsed position.

It should be evident thatvarious modifications can be made to the described embodiments without departing from the scope of the present invention.

We claim as our invention:

l. In a fulcrum adjuster having a barrel and a mounting post extending into said barrel, a bushing mounted about said post, said bushing having an enlarged annular shoulder extending radially therefrom, a valve sleeve received within said barrel and cooperating with said barrel to provide a leakdown annulus therebetween, said valve sleeve having an internal seating surface upon which the peripheral edge of said shoulder is arranged to seat thereby providing a valve element therebetween, and spring means urging said valve sleeve into seated relation with said shoulder.

2. In a fulcrum adjuster having a barrel and a mount-v ing post extending into said barrel, a bushing mounted about said post, a seal ring interposed between said bushing and said barrel, said bushing having a pair of arcuate shoulders of varying diameter thereon, a valve sleeve received within said barrel and cooperating with said barrel to provide a leakdown annulus therebetween, said valve sleeve having an internal seating surface upon which the peripheral edge of the larger of said shoulders is arranged to seat, a irst spring means urging the valve sleeve into seating relation with respect to said larger shoulder, and a second spring means between the smaller of said shoulders and said seal ring.

3. The adjuster of claim l in which said internal seating surface on said valve sleeve is a frusto-conical surface and said shoulder engages said surface in substantially line contact.

4. A fulcrum adjuster comprising a barrel having an axial passage extending therethrough, an axially bored post extending into said axial passage, a bushing mounted on said post, said bushing having passages therein communicating -with the axial bore in said post, a valve sleeve having an internal diameter substantially larger than the diameter of said bushing, thereby providing a reservoir chamber therebetween, said valve sleeve having an internal seating surface, said bushing having an annular shoulder proportioned to be received against said seating surlface, said bushing and said barrel being spaced apart below said shoulder to provide a pressure chamber therein, and spring means urging said shoulder and said `seating surface into seated relation.

5. A fulcrum adjuster comprising a barrel having an axial passage extending therethrough, an axially bored post extending into said axial passage, a bushing mounted on said post, seal means at one end of said barrel extending between said barrel and said bushing, said bushing having passages therein communicating with the axial bore in said post, a valve sleeve located between said bushing and said barrel and providing a leakdown annulus with said barrel, said valve sleeve having an internal seating surface confronting said bushing, said bushing having d a pair of axially spaced annular shoulders thereon, the larger of said shoulders being proportioned to be seated on said seating surface, a iirst spring means urging said valve sleeve into seated relation with said larger shoulder and a second sprinry means disposed between the smaller `of said shoulders an. said seal means.

6. The adjuster of claim 5 in which said internal seating surface is a frusto-co-nical surface, and said larger shoulder engages said surface in substantially line contact.

7. A fulcrum adjuster comprising a barrel having an axial passage extending therethrough, a post extending into said axial passage, a bushing mounted on said post, said bushing having an annular shoulder extending therefrom, a valve sleeve having an outer periphery which defines a leakdown annulus with the inner periphery of said barrel, said valve sleeve having an interior seating surface arranged to seat the edge of said annular shoulder, and a cellular seal disposed about said bushing and defining an expandible fluid reservoir with said barrel, said bushing, and said valve sleeve.

8. A fulcrum adjuster comprising a barrel having an axial passage extending therethrough, a post extending into said axial passage, abushing mounted on said post, said bushing having an annular Shoulder extending therefrom, a valve sleeve having an outer periphery which defines a leakdown annulus with the inner periphery of said barrel, said valve sleeve having an interior seating surface arranged to seat the edge of said annular shoulder, `spring means urging said surface into seated relation with said shoulder, and a cellular seal disposed about said bushing and defining an expandible fluid reservoir with said barrel, said bushing, and said valve sleeve.

9. A fulcrum adjuster comprising a barrel having an axial passage extending therethrough, a post extending into said axial passage, a bushing mounted on said post, said bushing having an annular shoulder thereon, a valve sleeve slidably received within said barrel and providing a leakdown annulus therewith, said valve sleeve having a -frusto-conical internal surface confronting said shoulder and arranged to seat said shoulder, a cellular seal element disposed about said bushing in spaced relation to said valve sleeve `to provide a fluid reservoir therebetween, and spring means urging said valve sleeve into seating relation with `said shoulder.

References Cited in the le of this patent UNITED STATES PATENTS 2,691,367 Thoren Oct. 12, 1954 2,795,218 Heiss lune 1l, 1957 2,863,430 Sampietro Dec. 9, 1958 2,873,730 Kilgore Feb. 17, 1959 2,966,151 Wood Dec. 27, 1960

Claims

1. IN A FULCRUM ADJUSTER HAVING A BARREL AND A MOUNTING POST EXTENDING INTO SAID BARREL, A BUSHING MOUNTED ABOUT SAID POST, SAID BUSHING HAVING AN ENLARGED ANNULAR SHOULDER EXTENDING RADIALLY THEREFROM, VALVE SLEEVE RECEIVED WITHIN SAID BARREL AND COOPERATING WITH SAID BARREL TO PROVIDE A LEAKDOWN ANNULUS THEREBETWEEN, SAID VALVE SLEEVE HAVING AN INTERNAL SEATING SURFACE UPON WHICH THE PERIPHERAL EDGE OF SAID SHOULDER IS ARRANGED TO SEAT THEREBY PROVIDING A VALVE ELEMENT THEREBETWEEN, AND SPRING MEANS URGING SAID VALVE SLEEVE INTO SEATED RELATION WITH SAID SHOULDER.