US2011863A - Valve lash adjusting mechanism - Google Patents

Description

Aug. 20,1935.

G. A. LOVETT VALVE LASH ADJUSTING I MECHANI SM Filed NOV'. 25, 1929 75 'V if 14'] Patented Aug.' zo, 1935 i 'UNITses*rs-'FFE s. mi* ENT fn-1?FIlCli-f A Y famleaffv vvsitvr LasnfAnJUsrrNG'MEonANrsi/r 'e George A. Lovett, Detroit, Michi, assignor KYto General Motors Corporation, Detroit,Mich., a `corporation oif Delaware l Appunti@ November 25,192.9,seria1 No. @9,582 soia-amis. (c1. ies- 90)rv A head-valve type.

1 The principal object of this invention'is to pro`- Inj the crankca'se, there is jour-V I vde means for automatically preventing binding matically adjusting a part of thepower vor motion is slidably lmounte'd suitable guides@ *I9 10' transmitting mechanism sojas to maintain inl the and extends through-the cylinder head toa-point mechanism, during the idle 'intervals in its cycles thereabove. 'n'coil spring 20, Which surrounds ofOperation, stress sufficient to eliminate slack a portion of theivalvestem I8, constantl'yfurges therein but insuicient to'r cause binding of 'the the'valve Il" to lposition toclose the port I6. '1 parts thereof, and to maintain the stress in theV A rocker 23, yon which there is provided an arnr 15 mechanism, during the workingintervals in its oy- 2li whichis seated on the upperfuend of t'hejvalvef4 cles of operation, less thanthat Whichvvould cause stem i8,v and an arni125 ,whose outer end is dis-A binding of thepartsjthereof. Of.' the 4several posed verticallyabove the upper end 'ofthe-push means lof this typewhich have beensug'gested, rod ill, isvpivotallymountedon ahollovv shaft i those Vwhich"havebeen most successful arethos'e 2i 'which lissupported by suitable 1braoketsf22 20. Y which consist of-a, hydrauiically damped spring 1 which aren'iountec'l on the* cylinder` head; devicev arranged to takeflup slackvlin the 'mecha- Througha'porticn of'the'Wall of the hollow shaft@ nism and to yield when thestressjin theme'cha-y 2 4] which is V surrounded bythe rocker 1 3, there nism reaches a predetermined limit'so as to preextends arropening` 3U, through Whichlubricant l Vent binding of thejparts of the mechanism.` which is `forced intothe hollow shaft by a snit- 25.

My invention relatesv to adjusting,mex'zhanisms` vrablef"pump may reach the' bearing; between thev of the'type describedin the preceding paragraph rockerand the sha-iti 'f Vand resides, particularly, in so constructing-and To thelow'er sdejof the hub portion ofthe arranging the elementsof the adjusting mecharocker 23there is pivotallyconnected a lever 26; nism as to eliminate therefrom certain defects Whichfi's coextensiveinlength with the'arm' 25,'V 30. AWhich Were prevalent in the mechanisms of the Thek juxtaposed sides'ofthe arm 2 5andthe1lever type described which, were known prior to the 26 arereces'sed to provide a space in which there time of my invention. c is located va hollovvl cylindricall element 2,1 'on For a better vunderstanding ofV the nature and which there is formed anipple 28 which is vthread'-A objects of thepresent invention, refere'nceismadeA y ed into the hub portion of the rocker. Through 35' to the following speoifieationin which are dethe nipple' and'terminating in thejeylinder'l, scribedthe embodiments ci my invention which f there extends a bore -Zl'vvhich is' adapted `to regare illustrated in the aceornpanying`` drawing. ister periodically with thielb'ore 3 0 inthe shaft 2|' In the accompanying drawing:v and through which lubricant is adapted to be Figure ljis a fragmentary crosss`ection through conducted into the cylinder 21; In the lower Side' -40 an internalcombustion engine of the overhead of the outer end of the lever Zijthere is `formedl valve type in which one embodiment of my inj a recess in which the upper end offthe push rodV vention is applied'to ythe valve-operating mechalli is seated. There extendsthrough the lever 26 nism. Y v, j abore'l ltlriroughwhich lubricant which leaks out Figure '2 is a fragmentary View showing a mod- Q fthecylinder 2 into the recess inthe upper side 45.' ined embodiment of.; my 'invention applied to the 'of thef'levermaybe conducted to' the bearing 'besame type ofl valvey mechanism as is shownv in tween the push rod and the lever. Figure-1. L" Y l in' the outer end of the/recessvvhich is formedin Figure 1 of thedr'awing in'whien I have, as between theieveif 26 and the, @m1 2.53m WllOSG" previously indicated, villustrated my invention Walls adjacentthe'outelend of the'armandthe 50 applied tothe valve-operating mechanismof in-v lever are convergent, there SlOCQd- Ka' ,Spllrl ternal combustionengine of the overhead'valve elementfl. Intheeylinder 21,* there isflocatedj type, the reference characters l@ and i t indicate, a plungerZ on Which'` there is provided areducedy y respectively, thevcrank case and the 'cylinder' head Y extens'on which bears against theelement Il., 55

of the parts of, or an undesirable amountof slack in, intermittently actuated power or motion It has, heretofore,y beenprcposed lto attain the Y end outlined above, bypro'viding means for autofof an' internal combustion engine of the over` of internal combustion'en- `nailed acam shaft I2 on which is'formeda cam I`3i which engages fthe lower end of 'a push rodvlli-,-

v whichiis sudably' mounted in 'suitable 'guides nos shown) inthe crankcase. -v The reference character lindicates a combustion chamber into Which opensa port I IiWhichfis adapted'toV be opened and closed"by `a poppet valveiTon which is provided, a stem lgwhijch Within the cylinder 21` and located betweenV the inner end thereof and the inner end of the plunger 32, therev is provided acoil spring 34 which constantly urges the plunger and the element 3l outwardly.

When the engine is started, the lubricant pump forces lubricant into the hollow shaft 2| and, thence, through the opening 33 and the bore 29,

into the portion of the `cylinder 21 at the inner end of the plungerSZ-and, as longgasgthe engine is operating, maintains' this portion' of the cylinder filled with lubricant. During that portion of each cycle of the operation ofthe engine, durv ing which the lower end of the pushzrod I4 isin.

contact with the dwell portion of the cam I3, there Will be no movement of thepush rod and the f spring `will maintain thevalve I-1 on its seat.

However, when the rise portion fof the cam comes into contact with the lower'end ofthe' push rod; thepush rod will be lifted vertically and the valve will, through 'the intermediary of the lever 26, the element 3l, the rocker. 23.and. the valve StemA I8, be openedyagainst thefresistance `of the spring 23,

and when the drop portion of the camcomes'into contact-with the, lower end of the Vpush rod,- the spring 20 will move the valve onto its seatfand throughtheintermediary of thevalve'stem I8, the rocker 23, Ythe element-3|- and theleVer 25,

maintain-thelowerend' of the push rod in contactk with Ythe cam. f

- Duringthe working intervals in thecycles off,

operationcf the valve operatingmechanism--Le.,

, during-those portions of the cycles of operation duringiwhich the lower endof the push rod. is in contact' with. the rise andy dropportions of theY camthe pressure exerted-f on the leverl by the push-rodl I4 will' cause, the former to swing in aclockwise direction about-'its pivctonthe rocker f andmovevthe element 3I andtheplunger E32-in- WardlyYforcing oil out ofy theiinner. part of the 1 cylinder. and into the hollow shaftZIl, and thus reducing7 the stress in thevalve operating VmechanismsV By reasonof thefact that the-push rodis Workingat al mechanical disadvantage, it will, s

not apply suicient force to thev plunger to'caufse e, more than a` very, small volume of the lubricant' Ytribe. discharged from the cylinder, even though ther bore 29 be relatively larger Y Y Y During. the; idle intervals. in the `cycles of. operation ofY the valve operating mechanism-i. -e.,, during. those portions of the cyclesv offoperation during which the loweren'd oi the pushrod is in` contact. with the, dwell portion ofthe camthe force exerted. by the lubricant plusA the force exelated the springA 3'4' on the plunger willY push plunger4 and ,the element'll outwardly and cause the-lever` 2Bto swing in' a counterclockwise direction about its-pivot. on the rocker, thus i'n-v creasing the'. stress inthe valve operating mechani'sm.. As, theY plunger.k moves ,outwardly the cylinder, thelubricantpum-p `vwillforce more oil ifritothe cylinder and thusmaintain Vthe cylinder lledl with .011. i

` I`f during the operation oftheengine, parts of'. thefvalve operating mechanism become exhanded by heat, Vor by any other means,` to such an ,extent as. would tend to cause them to bindand/or to cause the valve I1 to remain open. dur#V ing-thezidleintervals, the distance through which the plunger 32 movesinwardly in the cylinder 21 during the working intervals, will be/ greater than they; distance through vwhich the plunger movesj outwardly in` the cylindenduring thesucceeding idleintervalaand', consequently. the mean stress in/tle valveloperating,mechanism Willfbe gradualdecreased until" the tendency ,of the parts vofthe distance through which the plunger moves inwardly in the'cylinder,` during the succeeding VWorking intervals, and, consequently, the mean stress in the valve operating mechanism will be gradually increaseduntil the slack in the mechanism'is eliminated. It will, of course, be understoodthat the force `exerted by the lubricant plus the-force, exertedf'by the spring 34 onthe lever 26 is sufilcient to eliminate slack in the valve operating, mechanism, but, although it is Working at a mechanical advantage, is not sufficient to introduce, into the valvey operating mechanism,

sufficient stress to cause binding of theparts thereofy and/or. to open 'the valve I1 against the .Y

resistance ofthe spring 20.- WhenV therev is no tendency for the parts of Athe valve'mechanism- .to bind'or become slack and/or forv the valve I1 to-remain open, during the idleV intervals, the distance through which the plunger 32 moves outwardly inthe cylinder 21, during the idle intervals, will be equalto the distance through which the plunger` moves inwardly in the cylinder, during the succeeding working intervals, and, corisequentlyg the meanstress in thel valve operating mechanismA will remain constant. f Y

The distance through which the plunger 32'- movesinithe cylinder 21.4 during any cycle of the valve 'operating mechanism is very small, since the periodis very short andthe oil in the cylinder prevents` rapidA movement. of the plunger and,

consequentlyno suchfmovement of theadiusting mechanisn'iv aswould inl` itself cause noisy and faulty operation of thevalve operating `mecha-V nism will occur.`

Inthe embodiment of'theinvention which is `illustratedinFigurefZ.of the drawing,zthe reference characters. I,4, i8, 2E), and. 2|, as in the preceding figure, indicata'respectively, the push rod, the

` valve stem, the -valve spring and the-rocker supfporting shaft of. valve'operating mechanism of the type,shewninthepreceding gure. On the shaft 21 therejis pivotally mounted a rocker 35 on which. there is,f provided anarm 33which bearsV against the upper end ofthe valve stem I8 and an arm 31 which terminates vertically above the upper4 endof. the'push rod I4. Located between theouterendof the arm 31 and the upper end of thepush rodv I lA is the outer end of a lever 38 Whichisfulcrumed on the arm 31 adjacent its eX- t'remity butinwardly ofthe axis ofthe push rod. v

In the the lower side of the lever 33, there is prolvided a recess in which the upper end ofthe push redis seated...

There extends into andis secured .to the hub portion ofthe rocker 35 an arm 39Hwhichrcarries a cylinder 49 which is closed at its lower end and open at itsfupperV end. In the cylinder, there is located-a plunger 4 VI, on whichthere is provided -a reduced extension 42 which bears against the inner'end of the lever 38. Within the cylinder,

between-the closedge'nd thereof and the inner end ofthe, plunger, therev is located a coil spring 43A whichk urges the plunger 4 I, upwardly in the cylinder. rI fhrough. thearm. 39 and communicating at. one end with the portion of the cylinder 40 belowthe plunger l4I there extends a bore 44, which is adaptedto register periodically With a shaft 2| and through which lubricating oil isr here which extends through the wan of the adapted to be conducted to the bearing between the shaft 2| and the rocker 35, and through which lubricant` is adapted to be conducted into the cylinder lll).

To conduct lubricant from the hollow shaft 2| to the `bearing between the rocker 35 and the lever 38 and to the bearing between the lever 38 and theV pushrod M, there are provided a bore d5 which extends through the wall of Vthe shaft 2|,a bore il which extendsV through the arm 3l v of the rocker, whose inner end is adapted to register periodically 'with the bore 46 and which terminates at its outer endin the bearing between the arm 3'! `of the rocker andthe lever 38,

and a bore 18 whose upper end registers with the" outer end of the lboreal"and which terminates at its lower end in the lbearing between the lever` 38 and the push rodl i4. f

When the engineA is started, the lubricant pump forces, lubricant into the hollow shaft'ZI and,

thence, through the opening '135 and the bore @LA into the portion of the cylinder Ml below the plunger 4| and, so long as the engine lis operating, maintains the portion of the cylinder below the plunger iilled with lubricant. Further rthan to note that, since the cylinder 401s rigidly xed to the rocker 35, the oscillatory movements of the rocker will not cause the lever 38 to move with respect to the rocker, and that the angular posi'- tion of the lever'38 with respect to the rocker 35 determines the stress in the valve operating Y ber associated with the rocker, a lever on the rocker and-in engagement with the member, and an hydraulically dampedspring device carried by the rocker and operating on the lever to eliminate v. slack in and binding of the valve operating mechanism. Y l 2. In power or motion transmitting mechanism which includes a pair of power or motion y transmitting elements, means to eliminate slack in and prevent bindingof the'mechanism, in-

cluding amotion modifying element which enl gages one and is carried by` the'otherof the power or motion'transmitting elements, and an hydraulically damped spring device 'carried by yone of` the power or motion transmitting elements and spring deviceto eliminate slack inA and binding engaging the motion `modifying: element.

3. In power or motion transmitting mechanism` Y n which includes a pair of power or motion transmitting elements,v means to eliminate slack .in

Yand prevent binding of the mechanism, including a lever which engages one and is carried by the other of the'power` or motion transmitting elements, and an hydraulically damped spring device carried by one ofthe power or motion trans- Y mitting elements and engaging the lever.

4. Valve operating mechanism which includes a rocker, a hollow rocker shaft, an hydraulically damped spring device carried bythe rocker and having achannel for connecting it to the rocker shaft for iiuid supply, and a lever engaging the hydraulically damped spring device, the rocker and lanother element of vthe valve operating mechanism.

5. A rocker which includes a4 body portion and van element pivotally connected thereto, a wedging element located Abetween the body of the rocker and the rst-mentioned element, means "adapted to move the Awedging element in one direction, and meansto damp movement ofthe wedging element, the twolast-mentioned means including an hydraulically damped spring device which is located between the body of the rocker and the rst-mentioned element and engages'the wedging element. Y Y

6. lIn internal combustion engine valve operatingk mechanism which vincludes a rocker and ak hollow rocker shaft, a member associated vwith the rocker, a leverpivoted 4to the rocker and in .engagement with the member, an hydraulically ,n damped spring device carried by the rocker, fa

channel connecting the rockery shaftY with the Vhydraulic, cylinder. of thev spring gdevice, and

means operated bythe spring device and bearing on the lever to'eliminateslack in and bindingof v the valve mechanism. f Y

'7. In internal combustion engine valve operating mechanism which includes a rocker and a hollow ,rockerA shaft, a ,member operating the rocker, a lever pivoted to the rocker and contacting the operating member, the lever andone arm f of the rocker forming a U-shaped opening, an

hydraulicallydamped spring device secured tov the rocker within the U-shaped opening, a channel for iiuid Vleading from the spring device to Y the rocker shaftyand'means operated by the vice secured to the rocker, a channel for fluid connecting the device with thev hollow rocker shaft, an' independentarm carried between the end vof the rockerarm and the operating member and having its opposite end bearing upon the of the Valve mechanism.

' .GEORGE A. LOVETT.

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