US1588041A - Valve-operating mechanism - Google Patents

Description

Patented June 8, 1926.

, l UNITED STATES.'

roi-iN cQMoonn, or coNivnRsvILLE, INDIANaj 1 PATENT oF-FKI'C VALVE-OPERATING MEoHANrIsivr.

Application inea August 14, i920.I s eriai No. 403,490.

It'isthe object 4of my invention to Vprovide, a rocker-arm mechanism for operating the valves of internal. combustion engines, whereby the valve'starts its opening movement and finishes its closing movement relatively slowly .butinoves much more rapidly as the opening movement continues and during the t first part of the closing movement;v whereby au widez valve-opening is `quickly obtained, vand yet pounding of theA valve on its seatis prevented, the effect of differential expansion between cylinder and push rod, requiring undue clearances to avoid opening of the valves when the en- ,y gine is cold, is minimized, and a relatively large mechanical advantage is obtained for starting the valve'movement, which is of special advantagefor the exhaustvalve because ofthe gas pressure against which it operates.y This makes for greatly increased power in engine operation. V

In accomV lishing this result, I ,provide a vrocker arm which has a` rolling movement on its pivot and onv the push rod and valve 'j stein, whereby the push rod and valve stein may move in substantially straight lines and the pivotal point andthe points of contact of the rocker army with its three associated members are vshifted in the rocking;

operation so that in the valve-opening movement the power arm of vtheV leveriis shortened andthe work arm thereof is lengthened materially; Iand I vprovide the cooperating surfaces of the rocker arm and its pivotal surface yand the push rod with co-operating` pinsv and depressions which-1 prevent the parts rfrom relative slippage but dor not interfere with the rocking movement.

The accompanying drawings illustrate my invention: Fig. 1 is a fragmentary view, partly in section, of arocker arm mechaiiisin embodying my invention, withA the valve open;`and Fig.y 2is asimilar view with the valve closed. f

y The valve 10 is fixed on a slidable valve stem 11 to co-operatey with the valve seat l2 in the usual manner, the usual springs 13 being providedfor closing it. A. push rod 15v is mounted for vertical reciprocation by the usual cam 16 on the -camA shaft '17. These parts may be of any desired construction. e

'Ihepush rod 15 acts on the valve stem 11 through a rocker arm 20. This rocker arm has a convex curved surface 21 on the under face of its work arm, to co-operate with the plane upper end of the'valve stem l1.y It f hasa convex curved surface 22 on the under face of its power arm,"to co-op'erate'with the plane-upper end ofthe push rod 15.`

The upper yside of the rocker arin`20 has a pocket 23, the bottom of which is a convex, surface k24 whichbears against the/plane. lower face of a fulcrum' screwv vertically ad-` justable'in a suitablesupport 26 and held in adjusted position by a lock-nut 27.' yThe surfaces. 21, 22, and 24' are all convex .cylindrical surfaces, which rollon the respective plane surfaces formed by the stem,"rod, and

screw endswithwhich they co-operate, the convex downward surfaces 21 andv22 being e and the' surface 24 convex upward. i

Thus as the rocker arm rocksv fromr the position shown in Fig. 2 to the position shown in Fig-1, to open the vvalve 10, the points a andv c at which the surfaces `2'1`a'iid '22 engagetheir co-operating plane surfaces shift to the left(to cf and c respectively), while the point b at lwhich the surface 2a engages 'its co-operati'ng plane surface shifts to the rig-ht (to bf), thus shortening t the power armfrom bc to bpc and lengthening` the workarm from ab to cb. AThus the shifting of all three :points a, b, and c co-oper'ate iuvarying thelevera'ge ratio, ,toA increase the throw kof the valve stem 11 as' the opening 'movement vof the valve 10pro-l4` y gresses. The reverse Vtakes place on. the

closing movement of the valve, during which closing vmovement the valve Vstarts rapidly but ends'slowly, because of such`re-. verse change in' leverage ratio. vThis gives the push rod 15 arelatively large mechaiiical advantage instarting the valve 10l from its seat, minimizes the effect of dierential,

thecurvature of the surfaces 2l, 2.4:, and 22 i'sfmade' relatively slight, and such surfaces' are arranged to give substantially a true rolling motion on their respective associated plane surfaces.

this' relatively great los,`

ln onder yto prevent relative slipping between the rocker arm and its associated parts, the upper end 'of the valve rod l5 -and the lower end of the lfuflcrum ,screw 2525 .are provided with axially extending holes 3() and 31 respectively, Which may be simpler cylindrical holes; and pins 32 and i133 With projecting heads rare mounted in 'the rocker arm Q to project into such holes respective-ly. lhe heads olthe pins and '33 are preferably circular in cross-section, .and are curved azrial-iy, something like a gear tooth` addendum, being larger at their bases Where they abut against the rocker arm than at any other point. These pins co-,operate with the holes 'S0 andBl as the rocher anni 20 rocks,

to'hol'd such rocher arm fina definite position -vvi'tlh relation to the fulcrum screw 25 andthe push rod 15 so far as any slipping movements are concerned. v By shaping the heads =ot` the pins 32 and 33 as stated, they eliective'ly prevent slippage olf the rocker a transverse rivet 35, the ,nearer of suchr Washers being removed (and the rivet being shown in section) to show more clearly the cooperation of the surface 2l with the end of the valve stein ll.

I claim as my invention l. A valve-operating mechanism for internal combustion en-gines,'compr ising, in combination with the valve stein and a push rod, a rocker arm the ends of which engage the valve stein and the push rod, and a vfulcrum which an intermediate point oi the rocker arm engages, each yof the three pairs of engaging surfaces being arranged to rock on each other and shift the ypoints of inter-engagement, `said lulcruin and said push yrod being provided with holesvin their ends, and

pins carried by said 'rocker arma-nd having heads projecting into said holes.

2, .'valve-operating mechanism for internal combustion engines, comprising, in combination With the valve-stem and a push rod, a rocker arm the ends of which engage the valvey stein and thepush rod, and a ful-r cruin which an intermediate point of the rockerarm'engages, each off the Vthree pairs of engaging surtaces'being.arranged to rock on each other and shiit the points of interengagement, said tulciriun and said push rod being provided vvithholesfin their ends, and pins carried by said rocker arm and having heads projecting into said holes, the heads of said pins being convexly 'curved :axially so 'that they act as gear teeth in 'combination Y ith said holes to prevent slippage fWithout interfering with the roc ring movement.

3. A valve-operating mechanism for internal combustion engines, comprising a fulcruin, a rocker arm having at an intermediate point 'a rocking mounting on the under face of said fulcrum, a push rod and a valve 'stein upon the upper ends 'ol" Which the end portions of vsaid rocker arm have rocker inoun'tings respectively, said rocker mounting being arranged so that as either end ofthe rocker arm is moved vupwardly its point of Contact with the part co-operatin'g with that end is shifted toward the ul'cruin and the point of' contact o1 the rocker arm ternal combustion engines, comprising, lin` combination With the valve stem Yand 'a push rod, a rocker arm 'theend'sfo'f which lengage the valve stem 'and the push rod, and a ful-` crum which an intermediate 'part 'of 'the rocker arm engages, said rocker v"arm being provided at one endvWith a convex surface Which rollson the endoi said push .rodwhen the rocker arm is rocked, and 'said convex surface being provided with a p'roecting longitudinally curved tooth and sai `push rod with 'a hole into which said tooth projects` I u 5. A valve-operating mechanism 'for internal combustion engines, comprising, in

combination With the valve-'stem 'and 'a push rod, a rocker armthe'en'ds of Whichfen'gage the valve stein and the push rod,la'nd azfulcrum which an intermediate part of Jthe rocker arm engages, said rocker' arm being provided at one end and at such lulc'rum with convex vsurfaces which roll `on the .end

o'f'said push rod and on said 'ulcrum respectively when the rocker arm is rocked, and said convex surfaces being provided With projecting longitudinally curved 'teeth and said push rod and said 'fulcrur'n with holes into which said resp'ective'teeth project.

' In Witness whereof, I have hereuntol set my hand at Connersville, Indiana, this 111th day 'of August, A. D. onethousand nine hun,

dred Vand tWen'ty. v

- JOHNv o. Moons. e

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