US2614547A

US2614547A - Hydraulic valve tappet operable to vary valve-lift and valve-timing

Info

Publication number: US2614547A
Application number: US685431A
Authority: US
Inventors: Helmuth A Meinecke
Original assignee: Individual
Current assignee: Individual
Priority date: 1946-07-22
Filing date: 1946-07-22
Publication date: 1952-10-21
Anticipated expiration: 1969-10-21

Description

1952 H. A. MEINECKE 2,614,547

HYDRAULIC VALVE TAPPET OPERABLE T0 VARY VALVE-LIFT AND VALVE-TIMING Filed July 22, 1946 3 Sheets-Sheet 1 INVENTOR. fle/ma Z /7 Mei/16a ie.

Oct. 21, 1952 H. A. MEINECKE HYDRAULIC VALVE TAPPET OPERABLE TO VARY VALVE-LIFT AND VALVE-TIMING 3 Sheets-Sheet 2 Filed July 22,- 1946 INVENTOR. f/ezrruz z fl. Mez'lzecle.

Oct. 21, 1952 H. A. MEINECKE 2,514,547

HYDRAULIC VALVE TAPPET OPERABLE T0 VARY VALVE-LIFT AND VALVE-TIMING 3 Sheets-Sheet 3 Filed July 22, 1946 Patented Get. 21, 1 952 UNITED STATES PATENT a HYDRAULIC'VALVETAPPET OPERABLE o VARY VALVE-LIFT AND VALVE-TIMING I'Himuth A..Mi'necke, 'GitiSse Poifite, Mien; Application July 22, 1946, Serial No. 685,431 (01. 122 90) Claims.

- This' invention relateszto 'valve mechariism 1501' internal combustion engines and :more particularly to hydraulicitappet:mechanism for operating the:exhaust-and:intake:valves ofsuchlengines; an important "object of the invention heme "to provide an improved hydraulic tappet of the =se1i adjusting or' compensating 'type constructed and operable ifi improved "manner to alitoma'tially vary the "performance characteristics of -:the engirta a a 'Heretoiore, hydraulic tappets in eommeroiai use h'ave been employed in "the r operation of exhaust and intake' valvestor the purpose prelimihating tappet adjustment as wen as providing automatic compensation or takewp for play or consequent to clearance necessary ror valve stem expansiongwhieh int-he'case'of conventionarmechanical'tappets frequently results in noisy op erat-ion of the valves. A=eoiiifentionalcompeiisating-tap'pet ofthe hydraulic type usually comprises theother; -A-onewayehee1rvaIVe-is'generaHyin? terposed between the chambers to prevent the oil or hydraulic medium tfromreturning to the reservoir "chamber, the construction being such that bilistrappedin theupper chamber durin operation "and provides an incompressible hy= draiiiie cdlumn through *whi-oh the thrust of the oamispositively transmitted tothe'vaive without any'appreci'abl'e lostmotionthus ens'uring a'oon demand-predetermined timing of the valveand a fixed-opening "and closing operation-thereof. v

One of the aims of thepresent invention: is to provide a hydraulic'tappet mechanismwhich will not 'onlypossess any or 'all "orthe "advantages of the conventional sch-adjusting or compensating tappet but additional important advantages "in theimprovementotthe performance or the en gine and in permitting efficient operation overa' -wider power and 'speedrranga ity-is'well knownthst' an en'gine*d'esignedwith high'speee timing and-large 'zvalve :areas "to igive an early io ening an'tliate closing ofthe'v'alva: as =well as'a relatively wide or large opening-thereof, will produce up that least one third more maximum power, I but anengineso timed will either not runorwillop erate very inefficiently atzlow speeds Conversely, an engine designedwith lowspeed timing and l llivalve areas will operate advantageously at iovv :speetisrutwin not give 'effieient performanee at highspeedsi In view of t'hese limitationsit is customary to (provide valve sizes and timing which are acompromise between the two :extremes, yet whether such enginesare equipped with ordinary mechanical tappets or conventionalhydraulic compensating-tappets theoperation and performance characteristicsarenot satisfactory at the low and high speed-limitsof-the particular engine; and furthermore themaximum power available in theengineis notutilized.

It is an object of the invention to overcome these disadvantages and to provide an engine having an improved hydraulic mechanism pperable to vary the size of valve opening and the timing thereof in accordance with the engine speed so as to enable the engine to perform efli ciently throughout the range from low to hi gh speed while at the same timeincreasing the power output thereof. H

A. further obj ect of the in vention is ---to --provide an engine in which the efiectivemaximumopening of the valve,-.the-timing thereof and-thecam design are suchas are suitable for high speed operation and maximum power output, these characteristics being obtained at high speed I operation by transmitting the cam thrust to the valvewithout appreciable lost motion. However, the improved construction 'issuch that :as the speed is reduced a progressively iner-easing lost motion or telescoping action is introduced in the tappet mechanism between the cam andgthevalve alteringuthe valve'timihg and reducingthe lifter effective opening of the valve soastom mtam efficient operation. The compensating aet progressive between maximum "high and l ow speeds and at the latter limit the lost motion or telescoping action of the tappet mechanism is greatest, thus affording the propertir'hing and valve opening nee'ded'to enabletheen ine taperform properly at the'low speed "limit.

A rurther' Object ofthe invention is to provide a slf adjusting or compensating "hydraulic tapet mechanism wherein means is' :provided "for maintaining and ensuring efficient and uniform operation ilf'spdfill (if changes" iflLWiSDSifYbf the oil or other lubricating "medium "occasioned by fivariations. in the temperature ther'tm'i'.

Stillalfiothr05,1801;'df'thdihvfitifin is to pro vide a hydraulic tappet'device having a chamber inter osed between telescoping parts of the ta p'et through which oil i's circulated'during'opera tim -means being provided for eontro'uing the oil circulation in ac ordance with the "operatingspeedof'the engineto vary' 'thetelescoping a tion of "the tappet parts; the improved tonstmcfidn of the discharge orifice through the relative ex-.

pansion and contraction of metals having difierent coefiicients of thermal expansion.

Other objects of this invention will appear in the following description and appended claims, reference being had to the accompanying drawings forming a part of this specification wherein like reference characters designate corresponding parts in the several views.

Fig. l is a vertical section of a portion of an internal combustion engine illustrating one embodiment of the present invention.

Fig. 2 is a central vertical section taken through the chambered tappet body shown in Fig. 1.

Fig. 3 is a fragmentary sectional view, similar to Fig. 2, but illustrating a modified form of discharge orifice.

Figs. 4, 5 and 6 are fragmentary sectional views similar to Fig. 3 butillustrating further modifications of the discharge orifice or orifices.

Fig. '7 is a side elevation of the tappet body shown in Fig. 6.

Fig. 8 is a fragmentary sectional view illustrating a modification in the construction of the tappet body housing.

Fig. 3 is a plan view, partly in section, of the tappet body shown in Fig. 8.

Fig. i is a fragmentary sectional elevation, similar to Fig. 1, but illustrating another embodiment of the invention.

Fig. 11 is a fragmentary sectional elevation illustrating still another embodiment of the invention.

Fig. 12 is an exploded view illustrating the piston, cap and discharge jet comprising three of the parts mounted within the chambered tappet body of Fig. 10.

Figs. 13 and 14 are detail sectional views illustrating slight modifications of the discharge end of the jet and the associated recess inthe cap.

Fig. 15 is a sectional view taken substantially through lines l-I5 of Fig. 11 looking in the direction of the arrows.

Figs. 16 and 17 are views of the C-shaped spring shown in Fig. which assists in supporting the inlet ball check valve.

Figs. 18 and '19 illustrate diagrammatically the time of opening and closing of the intake and exhaust ports during one cycle of engine operation in which low speed and high speed, shown respectively in these views, are. obtained by virture of this invention.

Fig.. 20 illustrates a modified form of inlet check valve assembly.

Before explaining in detail the present invention, it is to be understood that the invention is not limited in its application to the details of construction and arrangement of 'parts illus trated in the accompanying drawings, since-the invention is capable of other embodiments and of being practiced or carried out in various ways.

Also it is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation.

In the drawings several embodiments of the invention are illustrated as applied to an internal combustion engine of the multi-cylinder type comprising a cylinder block Ell bored at spaced intervals to receive a number of valve stem sleeves or bushings, one of such bushings 2| being herein illustrated. The exhaust and intake valves, one such valve 22 being herein illustrated, are of the poppet or mushroom type, each having a depending valve stem 23 slidable in one of the guide sleeves 2|. Surrounding the lower portion of each valve stem is a compression spring 24 held in place at its lower end by a spring retainer 25, this spring normally urging the valve against its seat in accordance with conventional practice.

Referring to the embodiment of the invention illustrated in Fig. l, the lower portion 20a of the cylinder block below the valve stems is formed with a number of vertically extending bores in line with the valve stems, each adapted to slidingly receive a tubular or chambered tappet body 26 within the lower end of which is secured by a press fit an insert having a flat head 26a. engageable by a camlobe 2! secured to the cam shaft 28 of the engine.

Inasmuch as the various valves of the engine are controlled and operated in the same manner in accordance with the present invention, a description of the mechanism for accomplishing this purpose applicable to one valve will sufilce.

The tappet body 26, shown in detail in Fig.2, is formed with lower and upper

cylindrical chambers

29 and 30 separated by a transverse partition wall 3! which is formed with a central hole 32. Extending within the upper chamber 30 of the tappet body is a hollow cylindrical check valve cage 33 having its lower reduced end 33a press fitted within-the hole 32 in the partition wall 3|. Threaded into the upper end of the check valve cage 33 is a disk 34 having a central hole 35. The lower reduced end 33c of the cage 33 is'provided with a vertical hole 33b terminating at its upper end in a tapered seat engaged by a ball check valve 36. The cage 33 is provided adjacent the check valve with side ports 33a leading from the interior of the cage .into the chamber 33.

Slidably fitted within the, chamber 30 in the tappet body is a piston or plunger 31 terminate ing at its upper end in a reduced portion 31a engageable with the lower end of the valve stein 23, the piston 37 being removably held in position against withdrawal-by means of a split ring 38 snapped into position within a circular groove in the upper end of the tappet body. Interposed between the piston 3"! and the partition wall 3| and surrounding the check valve cage 33 is a relatively light compression spring 39 which isv adapted to maintain the piston 37 in contact with.

the lower end of the valve stem 23.

The tappet body is provided-immediately below the'partition wall 31 with anumber of holes ,or ports so which communicate with an annular groove 4! of somewhat greater height than the ports machined in the boss 23a of the cylinder block. The annular oil groove 4| communicates through a drilled passage 42 with a main oil inlet conduit 43 extending longitudinally in the cylinder block and connected to a source of lubricatgroove H there is machined in the boss 2011a second annular oil groove 44. Communication anewbetweenathevupperehaniber 3h oi tnetappet body and-the -oil groove 44 "is obtained through the medium "of a discharge port or orifice extending through the 'wall'o'f'thetappet'body. Inthe embodiment shown in Figs. '1 and 12 the "discharge orifi'ce or port isin the form o'fa two-diameter ho'le comprising a relatively large hole 46 terminating in a relatively small (hole 45 leading into the chamber-30. fI-he two-diameter discharge orifice 45, -46 permits, as hereinafter more fully explained, a controlled discharge oioilirom the chamber :30 into the-oil groove 44 and thence into a sump or trough 4.1 extendingllongitudinally in the cylinder block. Excess-oil over-flowing from this trough will spill into the crankcasaof the engine. I

.In the embodiment of Figs. 8 and :9 the tappet housing 20a :is modified to provide "a .relatively deep trough or reservoir-48 which communicates with both-of the oil-grooves and 44.v Oilifrom the engine lubrication system flows through a.

pipe 49 into the'upper end oi'the trough 48, which is open to the atmosphere, maintainingrth'e same filled at all times to overflowing. Oil :flowing downwardlyin the trough to the inlet oilgroove 4| passes through a'ziiine wire :mesh .soreen 50 which acts as a baflle or .filterrto prevent thepassage of air, foreign matter or gaseous' oilbubbles into the space below .the'screen-and, hence, into the inlet oilgroove 4|. The constructionshown inFig. '8 may be used with the tappet mechani'sm or the embodiment'of Fig. 1 and hasan advantage in that the tappetswilloperate'quietly commencing with the1firstrevolution of the engine crankshaft regardless of thexoil pressure. -A furtheradvantage resideslinthe fact that air or gases picked up by the engine oil pump will-escapefrom the upper part-of the trough 48 before proceedinginto the tappet body.

.In Figs. 3 to 7 inclusive there are illustrated several modifications in respect to the discharge ports from the upper chamber .30 of the tappet body 26. In Fig. 3 the discharge port comprises a'cur-ved milledslot iin theouter wall of the tappet body which communicates centrally with asmallrdrilled hole 52 :leading into the chamber 30. In Fig. 4 the dischargeportcomprises az'series of-small. holes 53 arranged. in-vertically spacedrelati'on. These holes may be arranged'in vertical alignment or maybe-staggered laterally while at thesame time spaced verticallyin the manner illustratedin Fig. 4. In Fig.5 the exhaustiportproviding communication between the chamber 30 and the-oilgroove 44 comprises a small drilled e p per m i g :or the small cclrilledihdle: 54 in Fig. 5. It is considered important, in order to Fcau's'e the tappet to "change ttiming with an increase or decrease of engine speed, that the discharge of oil from the upper 1 chamber 30 of the tappet body through the discharge port :be

at -a low rate but of considerable :duration 201 length'of time i at 1- the beginningior :each cycle or. operation. This'important operating chara'c'teris'tic "is achieved by forming the discharge 'ports in the tappet body in accordance with any oneof the embodiment illustrated in lFi'gs. 2 to 7 inclusive. 1

In the embodiment oftheinvention illustrated in Figs. '10 and :12 the tappet body comprises at relatively thin walled cylindrical I member 6 fering from the tappet body of Fig. 1 by the elimination of "the e-partition mm '31. 'The 'interior of the tappetbody forms a 'chaniber 'iil "elosed at its "lower end 'bymeansof a. shoe'or insert member58 terminating in a fiat head engaged by the cam'lobe 2! onthe camshaft '28. slidable withinthe upper end of the tappet body 55 is a piston 59 "comprising an upper cylindrical head 59a (Fig. 12) having an undercut portion 5% intermediate its :upper and lower ends "forming with the wall of the tappet body an annular chamber or recess 60. The piston head 59a is formed with an integral depending hollow cylindrical "stem 6 l extending downwardly -to "a point proximate to the shoe 'or insert member 58, there being a predetermined clearance'between the 1"ow-' er end of the stem SI "and 'theshoe .58 'so as "to permit the desired telescopic actiono'fth'e' piston and tappet body during operation. Anumber of radial ports or ducts ;62 provide communication between aninner cylindrical chamber 63 in the hole extending through the wall :of the tappet I ning of :every cycle of operation, the width of l the slot determining how fast or at what'rate the discharge can occur. The discharge characteristics of the narrow vertical islot 55in the emdimentcr-Figs. 6 and 7 may be obtained by the two-diameter discharge ports "of Figs. 12 "and 3m the vertically spacedrholesia'iinFigM "or by piston 59 and the outer annular chamber 60. This latter chamber communicates with the undercut oil groove 44 in the tappet housing by means of a discharge port or duct '64.

Mounted within the piston "59 is a discharge jet-stem 65 which terminates at its'lower end'in ajhead 65a. fitting within the lower end of the stem 6l to provide a closure therefor, the 'lhead 65c being rigidly secured to the piston stem 51 as by means of a transverse pin. The portion of the jet. stem 65 abovethe-head'BEa which extends through the piston stem (ii is .oflless diameter so as to provide a narrow. annular chamber around the jet stem. The piston stem .5! ligprovided with a number of vertically spacedportst'i providing communication between the chamber 51 in the tappet body and the chamber'fidsurrounding thejetstem B5, The latter is provided at a point immediately below the piston head 59a with aligned transverse holes-68 leading from the chamber 66 into a vertically extending passage 69 in therjet stem which is in the form of a hole drilled from the upper end of the jetstem downwardly to a :point immediately below the transverse hole 68.

Secured by means of-ap-ressfit within a counterbo-re 63a. in the upper end of the piston head 59a is a cap 10 which projects upwardly beyond the piston asufiicient distance to cause the upper end 10a of the cap to engagethe lower endoi the valve stem 23. Thecap is boredto provide in'its lower end a chamber 1 l o-i'larger diameter than the jet stem 65 and within which the upper end of this stem is housed, there being-a clearance between the upper end of the jet "stemand the upper wall 1 lb of the chamber 1!. The cap '10 is maintained constantly in engagement with -the lower end of the valve stem 23 :by means oi ia relatively light coil spring 12 surrounding the pistonstem BI and interposed between the shoe 58-and thev bottom of the piston head. From the foregoing construction it will be seen that oil from the chamber 51 inthe tappet body may flow through the ducts 6'! intothe chamber. 66 surrounding the jet stem 65. Thence theoil may flow through holes 68 into the drilled passage 69 in the jet. Oil forced out of the upper end of the jet will pass into the chamber 63 in the piston head and thence outwardly through the holes or passages 52 into the annular chamber 6d formed by the undercut 59b in the piston head, From thechamber 60 oil may flow through the discharge port 64 in the tappet body into the outlet oil groove 44 and thence into the trough or sump 47 1 Figs. 13 and l'illustratecertaln modifications in the construction of the cap iii and upper end of the jet 6'5. 1 In Fig. 13 the upper end of the jet is tapered to provide a substantially frustoconical end which is positioned within a conical recess-l3 formed in the upper end of the chamber H in thecap. InFig. 14 the upper end of the jet is counterboredto receive an insert M which may be-f vhardened steel to provide a nozzle which will be highly, wear resistant against disintegration due to the velocity of oil forced out of the end of the nozzle or jet. 7

In'the embodiment illustrated in Fig. lithe construction is substantially the same as in the embodiment of'Fig. 10 with the following exceptions. In this instance the upper drilled end 55a of the jet stem '65 is shortened so as to cause its upper discharge end to terminate at a point somewhat lower than the exhaust port M in the tappet body. Extending into a bore in the cap 79 and pinned thereto at it is a member it having a recess 75a. in its lower end in line with the upper end of the jet, this member providing a cap for the jet suitably spaced from the upper end of the jet to permit the discharge of oil therefrom into the inner chamber 63 in the piston head. Oil from this chamber finds its outlet through the passages 62 into the outer chamber iii) in the piston head and oil from this chamber is dis-v charged through the discharge port 64 into the undercut oil groove t land thence flows into a trough or sump 16. In this embodiment the trough 16 is similar to the trough 38 in Fig. 8, being in constant communication with the inlet and outlet grooves ii and M. A fine mesh wire screen]? 'is mounted in; the trough and functions similarly to the screen in the embodiment of Fig. 8.

Referring to Figs. 15 to 1'? inclusive, the tappet body in Figs. and 11 is provided with an inlet passage 18 within which is rigidly secured a tubular insert member '39 terminating in a head 79a machined to provide a ball check seat. A C- shaped'spring 80 is snapped into position within the tappet body 58 and has a hole 8! fitting over the head 1 9a so as to hold the spring in position. A leaf spring 82 is secured at one end to the end of the spring 80 and is formed at its opposite end with an apertured portion 83 receiving and retaining a ball checl: 84 cocperable with the taperedseat in the insert member 19.

In the embodiment illustrated in Fig. 20 the insert member '59 in the inlet passage 53 terminates in a ball check seat 85 adapted to be engaged by a resilient ball check. 86 which may be formed of rubber-like material, such as neoprene or other synthetic or natural rubber substance. The ball check 86 is carried-by a shroud or retainermember--81 which is secured to theendof the l'eafspring 82; the latter being supported by the C+spring B0 in the same manner as shown in Figs. 15 to 17 inclusive. "Ihecheck valve constructions illustrated in the embodiments of Figs. 15 to 17 inclusive and 20 not only control effectively the flow of oilthrough the inlet passage 78 but .also permit the mounting'of the check valve within the tappet body without interference with the piston stem 6 I Heretofore,- serious disadvantages and limitations have been encountered in conventional internal combustion engine on account of; thefact that the efiectiveopening and closing of valves have been fixed or constant. These characteristics have been governed by the size of valve and the contour of the cam selected for the particular engine. "No appreciable variation in' these characteristics occurs in the operation 'of the conventional engine throughout the speed range thereof. 'AS a'result an engine with a predetermined valve timing will only give satisfactory performance within a given speed range. For eX-' ample, an engine having valve sizes and timing selected topermit eificient operation at relatively low speeds will be limited as to its upper speed range and will not produce the power obtainable from. an engine timed for high speed operation. In Fig. 18 there'is illustrated a typical low speed timing diagram in which the curve ac represents the degrees'of opening of the intake valve between the lines at and m", and the curve y represents the degrees of opening of the exhaust valve'be-i shown in Fig. 18 will be made in order to suit the particular engine. In Fig. 19 there is illustrated;

on the other hand, a typical timing diagram for ahigh speedengine having much highermaxi-- mum poweroutput but incapable of operating efficiently at low speed. In thiscase the period of opening of the intake valve is from line r to line x'as shown by the curve as, the valve opening 43 before top dead center and closing after bottom dead center. The period'of opening of the exhaust Valve, as shown by curve 1 is from before bottom dead centerto a point 32 after top 'clead'center.- The much greater overlap of the exhaust and intake valves in this case permits the desired high speedoperation;

and an engine-timed in this manner will produce at least one-third more power than an'engine timed accordingto the diagram of Fig. 18 but will not function eniciently at low speed.

Engines timed as in Figs. le'and 19 are generally. designed for special purposes. Hence, engines constructed for general purposes, such as for passe'ngerlautomobile's, are givena compromise tim'-" ing'between these extremes. In accordance with a typical average speed timing the intake valve may Open at 10 before top dead center and'close at;a point'dO after bottom dead center, and the exhaust valve may open at 50 before bottom dead" center and close .at 10 after top dead center.

It is possible by virtue of the present invention The exhaust valve throughout the speed -ra ge therebetween. Accordinglyjtheexhaust and intake valve. areas maybe made. large to'give the maximum openings needed for-maximum engine speed and the cams 2?! designedso as totime theopening and closving of the valves are given the maximum liftto;

the.-valves at the; top speed selected, suchas the" high. speed. performance .available with the timving indicated in Fig. 19. However, by introducing .into the tappet mechanism in accordance with the present inventions. telescoping action which varies in direct proportionto the engine speed. and to control under all operatingconditions the flow of oil induced by the telescoping action itis possible to alter'both the effective valve openings andthe. normally set timing shown, forexample, in-Eig. 19.. and to progressively vary thistiming 'asweH. asreduce the amount of eifective; open .ingofjthe valves sothata low speed timingzsuch as-illustratedirr Fig; 18, orany intermediate-or.

averagegspeed timing. will result at. predetermined stag s in; the engine. operation. .In otherwords,

by virtue of thetelescoplng action ofrthegtappet mechanism, and theicontrol ofthe oiltfiow; the

timing and effective opening of :the valves: will be automatically altered togive. the. timing rand valve opening neededfor mosteificient operation atiallspeeds.

The operation of the tappetmechanismv shown I in the embodiment of Fig. 1 is as follows.'"-With theparts positionedas shown, oil under'pressure 'fromthe inlet conduit 43 andinletoilgroove .4! .will'enterthe chamber 29 in the tappet body throughports 40. From this'chamber oil will flow through passage 33b pastjtheball. check 36 into the. ball check;cage 33 and thence through ports '-33 a1.and. into the upper chamber 30in the tappet body, Oilwillfiow out. of thejchamber. 3Z5 into the. upper oilgroove 44 through the exhaust .port45, or ports, 52-55. Thus, with the parts 7 positioned as shown in Fig. 1 a. circulation of oil willbe created. from the inlet-oil conduit 43 to the; outlet sump or trough41, the oil entering the tappet body through ports and exhausting through port 45. Asthe tappet body 26 islifted by th cam 2.1 the column of oil within the upper chamber 30 of the tappet body will decrease. in

height so long as the discharge orifice 45', 4E .registers or. is in. communication; with theoil groove44 since oil during this time will h e-forced out. ofthe chamber 30 into the outlet oil groove 44.. While. this'occurs, the vtappet body willgtelewards. relatively to. it. without raising the valve.

. A lost motion between these parts is thereby cam. I

It will be apparent that the amount of oil 'fOlCBdQOI. pumped out-of :the tappetbody chamher: 301 through discharge-

porn

45, 46:.during1 the initial riserof the tappet body under the thrust of .thecam wilLdepend upon the and locationnf this... port and. the 1 n'gth of time. thatthe rt isv in communication with. the. outlet, oilgroove 44, andhence the. amount of:oilthusldischarged from the tappet body'will determinethe extent of telescopic: action-or. lost mdtiontravel of.-the

.tappet body relativetolthe piston-31.. At....the slowest speedof-the engine, therefore the. telescopic actionwill be greatest, since the; exhaust port or orifice 1l5',..46 remains uncoveredtor the .lon'g'estinterval 'of' time. This resultsin allate opening of. each. valve, suchas illustrated in-IFig.

18.; Moreover, since the .1 telescopic action is greatest at this speed the cam willdiftthe'valve ,the least. height, thus. pIOVidiI'lg;

t e in um efiectivejopening.mast,thevalve...

As. theengine speed is .gradually increased he exhaust. port;45,- 4-6 will remain-uncovered-ior graduallyashorter intervals ofxtime, andzhence thecirculation of oil-{through .the'tappetbody will v progressively decrease.- This will-be accompanied by, a progressive increase in. height ;o f-. .,the solid column ofoil in the-chamber 30 causing the cam gtocommenceits lift ro'f'the valve at progressively earlier. stages. As the height of this; solidror incompressible column of oil in the tappet chamber increases; the-height. that vthe cam. lifts-ythe. yalve 22.- will progressively and proportionately increase,

and. furthermore the? timing of; each valve 1 will change; givinganincreasingly earlieropeningand later. closing thereof. At or near-the; top speed of theengine the exhaust port-45,46 will-reciprocate into and out of registry with 'the' outlet oil passage 44' so. rapidly that no 1 appreciable amount of oil will. be discharged;;.Under this operating condition there will. be nov appreciable telescopic'action-or lost-motion between; the tappet body andpiston-fi, and'hence the valveoperation will be substantially the same as; if. the tappet body andpiston were one piece; Thisiiwill make available the'maximumpower output/with av higlr speed valvetiming such' as iszshown-in Fig. 19 accompanied. by'max-imum, lift; and efiecjtiveopening of thevalve.

- It will be understood that duringzclosing. mots mentof the valve accompanied by; expansion.' of

I thespring 39 oil. willbe: drawn. by suction: from the lower chamber 29 in the tappet body-pastzthe checkvalve 3.6. into. the.- upper. chamber 3.0; 1 thus scope: on the. pistonIor-plunger 31, movin-g up replacing the; oil that-has'beendischarged. from the upper chamber 30 during the telescopic action; By' controlling the passage 3312* by means of f checkzvalvesfi .leakage'sor oil .under: high pressure .from. chamber Bilinto chamber!!! and thence through the intake; ports..- 40. and; aroundthe tappetbodywillbeprevented v '1 p Arr importantfeature of the invention resides in. the: size, shape and location of the. exhaust .portin'the upper'chamber 30. Inxordento 0btain 'efficient' results in respectto changes-intiming consequent to: changes in enginerspeedgthe discharge: from the. upper: chamber, in-ath'e: em-

bodimentiof Figs. 1 to? inclusive; should'beiat' alow rate but over a considerableduration ior interval-of 'tirneduring the beginning of-the-cycle' ofv operation of thecam. Hence, the heightl of the discharge portfdete'rmines the duration-101' length of time thatthe discharges-o ..oil from chamber 30 occurs and @the' width ofithe discharge port'determines the rateof discharge.

. Thus, in'Figs'. 1 and-2 the duration of. discharge is determined bytherelative heightsofj portion 46 of thedischarge port and the outlet soil'groove M Since-theportionAdof the exhaustport'has a'much smallerdiameter; or. size tharrtheportidn 4.6. andza: much-less..width;-or diameter; than: the

height of groove 44, alow rate of discharge will be produced, In the embodiment of Fig. 3 the milled slot 51 will give a discharge of 011 of relatively lon duration whereas the small hole 52, similar to hole 45, communicating therewith will give alowrate of discharge similar to that obtained in the embodiment of Figs. 1 and 2. In the embodiment of Fig.4 the discharge port53, consisting of anumber of small vertically spaced holes similar tov hole 45, will produce substantially the same resultsas in the embodiments of Figs. 2 and 3, giving a discharge of considerable duration of time but at a low rate. In the embodiment of Fig. 5 the small discharge port or orifice 54 is positioned so as to remain in cominunication with the oil groove 44 for the desired interval of time, and since the diameter of this port is considerably less than the height ofthe oil groove, as in the case of holes 45, 52and 53,

a relatively slow rate of discharge will occur. Similarly, in theembodiment of Figs. 6 and '7 the discharge port 55, which is in the form of a narrow slot similar in width to slot 5|, will proclearance between the lower end of the piston stem BI and the shoe 58. Upon engagement of the shoe with the lower end of the stem a positive mechanical lift of the valve will occur. In

'possible to utilize an exhaust port 64 of uniform diameter and greatly increased effective size as compared with the previous embodiments, thus minimizing any danger of this port clogging during operation due to foreign matter in the oil supply.

Thermal control of the flow of oil through the port 64 is achieved in Fig. 10 by varying the clearance between the upper end of jet 65 and the juxtaposed face of the cap 10. For example; the piston 59 and cap 10 may be formed of steel and the jet 65 of a metal having a higher coefii- .cient of thermal expansion, such as aluminum ner, therefore, amounts in effect to a variation in the size of the discharge port and enables the present device to operate efficiently and uniformly throughout the oil'temperature range. It will be understood that the effective discharge open- 7 ing ofthe jet may be varied to a greater or less or magnesium. Assuming that it is desired to varythe discharge opening or clearance between the jet and cap from .003 of an inch to .006 of an inch in order to compensate for viscosity changes throughout the oil temperature ranges encountered in engine operation, then the relative clearance will be in substantially direct propor-- tionto the increase in oil temperature and the decrease in the viscosity thereof. Varying the clearance between the jet and cap in this manextent than above described in order to suit the particular engine. Other metals, or alloys thereof, may also be utilized in order to obtain the desired differential in linear expansion and contraction rates between the jet and cap.

In the embodiment of Fig. 11 the jet member is made shorter and the cap member l5 is formed of the same metal, such as aluminum,

as the jet. These members are anchored at opposite ends to the piston. I-Ience, during operation the jet 65 and member l5 will expand toward each other relative to the piston 59 when heated in response to the rising temperature of the oil. Conversely, these parts will contract away from each other as the oil temperature drops. This will result in either reducing orincreasing theeffective discharge opening between the upper end of the jet and they juxtaposed surface 15a of the cap member. As in the embodiment of Fig. 10, the amount of this variation will be substantially directly proportionateto the variation in temperature of the oil and in viscosity thereof.

I claim:

l. A cam actuated valve mechanism for actuating the valve of an engine, comprising a'pair of relatively movable members having upper and lower communicating chambers adapted to have a hydraulic medium interposed therebetween in the variation said chambers, a support Within which one of said members is reciprocable, inlet and outlet conduits in said support, ports in said reciprocable member adapted to communicate with said con duits to provide for relative movement of said members at one time and adapted to reciprocate relative to said conduits during reciprocation of said reciprocable member to vary said relative movement, means for checking the iiow of the hydraulic medium in one direction from one of said chambers, and means within one of said members responsive to the temperature of the hydraulic medium for controlling the flow of said medium through said outlet conduit to compensate for viscosity change of said medium.

2. A cam actuated valve mechanism for actuating the valve of an engine, comprising a pair of relatively movable members having upper and lower communicating chambers adapted to have a hydraulic medium interposed therebetween in said chambers, a support within which one of said members is reciprocable, inlet and outlet conduits in said support, ports in said reciprocable member providing communication between said conduits and chambers to provide for relative movement of said members at one time and adapted to reciprocate relative to said conduits during reciprocation of said reciprocable member to'vary said relative movement, means for checking the flow of the hydraulic medium in one direction from one of said chambers, and means within one of said members responsive to the temperature of the hydraulic medium for controlling the fiow of said medium through said outlet conduit to compensate for viscosity change of said medium. I

3. In a hydraulic tappet mechanism for actuating the valve of an engine, a fixed body, a tappet including a pair of coacting members arranged within said body in telescoping relation,

"tappet res'ponsiveliquid for controlling -the'flow of the liquid tuating the valve of an engine;

I the mummy liquid intdthe-lattem means for varying the rate fof discharg'e of the liquid from the tappet-thereby vary the valve-lift and timing thereof comprising outlet conduit means in the chambered member and body through w hich the" discharge ofliquid-is governed by the speed of reciprocation and viscosity of the liquid, and means within said to the temperature 2 of the through said outlet conduit meansto compensate for viscosity change of, the liquid.

4:. Ina .hydraulic talipefijmechanism for' ac a fixed body, a tappet including a pair of coacting members arranged within said body in telescoping relation, one of said members being chambered to contain a body of liquid interposed between the membersand through which the thrust of a cam is transmitted to the other member for shifting the valve toward open position, inlet conduit means in the body and chambered member 'for introducing liquid into the latter, means for varying the rate of discharge of the liquid from the tappet thereby to vary the valve lift and timing thereof comprising outlet conduit means in the chambered member and bodythrough which the discharge of liquid is governed by the speed of reciprocation and viscosity of the liquid, and means including an expansion element in said chambered member responsive to the temperature of the liquid for controlling the flow of the liquid through said outlet conduit means to compensate for viscosity change of the liquid.

5. In a hydraulic tappet mechanism for actuating the valve of an engine, a fixed body, a

tappet including a pair of coacting members arranged within said body in telescoping relation, one of said members being chambered to contain a body of liquid interposed between the members and through which the thrust of a cam is transmitted to the other member for shifting the valve toward open position, inlet conduit means in the body and chambered member for introducing liquid into the latter, means for varying the rate of discharge of the liquid from the tappet thereby to vary the valve lift and timing thereof comprising outlet conduit means including a port in the wall of the chambered member adapted tointermittently communicate with a passage in said body to provide for relative telescoping movement of the members and shiftable out of communication with said passage to provide a substantially positive hydraulic connection between the members, and means within said tappet responsive to the temperature of the liquid for controlling the discharge of the liquid through said outlet conduit means to compensate for viscosity change of the liquid.

6. In a hydraulic tappet mechanism for actuating the valve of an engine, a fixedbody, a tappet including a pair of coacting members arranged within said body in telescoping relation, one of said members being chambered to con-. tain a body of liquid interposed between the members and through which the thrust of a cam is transmitted to the other 'member for shifting valve toward open position,- inlet conduit means in the body and chambered member for introducing liquid into the latter, means for varying the rate of discharge of the liquid from including aport ti-miirigthereof comprising ou e in the wall of the chambered memberadapted-= to= intermittently: communicate withe -passage; in'saidbody to provide 'for rel'ative telescoping movement ofthe members' and shifte able out of communication with saidi passage to provide asubstantially positive, hydraulic connection between" the members, and means including an expansion element in the chambered member responsivev to the temperature ofthe liquid for controlling the discharge of the liquid through saidoutlet conduit-meansto compensate for-viscosity changeof'the liquid. j.

'7'. In a hydraulic tappet mechanism fort-ace tuating the valve-of an enginehaving: aifixed body, a tappet including a pair of coacting members---arrange d in saidbody for relative movement, one of said members being chambered to contain a body of liquid through which the thrust of a cam is transmitted to the other member for lifting the valve, inlet means for introducing liquid into said chambered member, means for varying the rate of discharge of the liquid from the tappet thereby tovary the valve lift and timing thereof comprising outlet conduit means in the tappet and body through which the discharge of liquid is governed by the speed ofreciprocation and viscosity of the liquid, and means in said tappet responsive to the temperature of the liquid for controlling the discharge of liquid through said outlet conduit means to compensate for viscosity change of the liquid. 1

8. A hydraulic tappet mechanism comprising a support having a cylindrical tappet body in said bore having a liquid chamber,

a plunger associated with said body and adapted to receive the thrust of said tappet body through the column of liquid in said chamber, means for introducing liquid into said chamber, means for varying the discharge of liquid from the chamber thereby to vary the valve lift and timing thereof comprising a conduit in said support opening into said bore and adapted to register with a port in said tappet body constructed to discharge liquid therefrom in amounts varying in substantially direct proportion to the viscosity of the liquid, and temperature responsive means in said tappet body for controlling the discharge of liquid to compensate for viscosity change of the liquid.

9. In a hydraulic tappet mechanism for actuating the valve of an engine having a fixed body, a tappet including a pair of coacting members arranged in said body for relative movement, one of said members being chambered to contain a body of liquid through which the thrust of a cam is transmitted to the other member for lifting the valve, inlet means for introducing liquid into said chambered member, means for varying the rate of discharge of the liquid from thetappet thereby to vary the valve lift and timing thereof comprising outlet conduit means in the tappet and body through which the discharge of liquid is governed by the speed of reciprocation and viscosity of e the liquid, and means within said tappet responsive to the temperature of the liquid for controlling the flow of said liquid through one of said conduit means to compensate for viscosity change of the liquid.

10. In a hydraulic tapp et mechanism for actuating the valve of an engine having a fixed body, a tappet including a pair of coacting members arranged in said body for relative movement, one of said members being chambered to contain bore, a reciprocable a body of liquid through which the thrust of a cam is transmitted to the other member for lifting the valve, inlet means for introducing liquid into said chambered member, means for varying the rate of discharge of the liquid from the tappet thereby to vary the valve lift and timing thereof comprising outlet conduit means in the tappet and body through which the discharge of liquid is governed by the speed of reciprocation and viscosity of the liquid, means within said tappet responsive to the temperature of the liquid for controlling the flow of said liquid through one of said conduit means to compensate for viscosity change of the liquid, and check valve means for checking the flow of liquid in one direction in said chambered member.

HELMUTH A. MEINECKE.

' 1 6 REFERENCES CITED The following references are of record in the file of this patent:

5 UNITED STATES PATENTS Number Name Date 1,727,790 Shutts Sept. 10, 1929 1,930,260 Almen Oct. 10, 1933 1,994,223 Leveque Mar. 12, 1935 10 2,011,864 Lundh Aug. 20, 1935 2,090,795 Johnson Aug. 24, 1937 2,175,465 Johnson Oct. 10, 1939 2,393,793 Meth- Jan. 23, 1946 2,484,109 Meinecke Oct. 11, 1949 15 2,539,877 Voorhies Jan. 30, 1951 FOREIGN PATENTS Number Country Date 213,499 Great Britain Apr. 3, 1924