US2185991A

US2185991A - Tappet construction

Info

Publication number: US2185991A
Application number: US94040A
Authority: US
Inventors: Voorhies Carl; Harry E Voorhies
Original assignee: Eaton Manufacturing Co
Current assignee: Eaton Corp
Priority date: 1936-08-03
Filing date: 1936-08-03
Publication date: 1940-01-02
Anticipated expiration: 1957-01-02

Description

Jan, 2, 1940.` ci VOORHIES Er AL 2,185,991

TAPPET CONSTRUCTIONv Filed Aug..3, 1936 2 Sheets-Sheet 1 2.5 v. lu.

, 1 3e" Agi. 4.

Jan. 2, 1940.

C.- VOORHIES ET AL TAPPET CONSTRUCTION Filed Aug. 3, 1936 2 Sheets-Sheet 2 INVENTORU- Car-Z yaorzes,

A@ 9 ORNEYS.

Patented Jan. 2, 1940 UNITED STATES OCT 21 1941 PATENT OFFICE 2,185,991 TAPPET CONSTRUCTION Carl Voorhies and Harry E. Voorhies, Detroit,

Mich., assignors,

Eaton Manufacturing Company,

by mesne assignments, to

Cleveland,

Ohio, a corporation of Ohio Application August 3,

19 Claims.

This invention' relates to automatic compensating tappets for operating such parts as intake or exhaust valves of internal combustion engines, and more especially relates to improvements in the construction and arrangement of tappets of such character. l

The principal object of the invention is to improve the automatic compensating mechanism of tappets especially adapted for operating movable parts of internal combustion engines.

Another object is to provide in a device of the above character a novel check valve construction and arrangement of such nature that the check valve means is closed by a force substantially equal to the force exerted by the engine valve 'operating gear when the engine valve is open.

A further object is to provide a novel plunger construction for hydrauliccompensating tappets which includes means providing a seal between the plunger and its cylinder, and an inlet yport and a check valve means for the hydraulic compensating chamber of the tappet.

It is also an object of the invention to provide for a uniform rate of leakage from the hydraulic compression chamber of the tappet and to employ a single element adapted to abut aplain surface for 'controlling such leak-down rates so that a single element may be accurately manufactured by coining or stamping process.

Another object is to provide a system of construction which obviates the necessity of selec tive or other accurate tting of plunger parts with respect to the cylinder therefor.

A still further object of the invention is to provide, in a tappet construction including a cylindrical body and a plunger arranged therein, for a mechanical hysteresis eect, i. e. a lagging or retardation of the movement of the plunger relative to its cylinder when forces acting axially upon the tappet ends are changed.

Another object is to provide, in ka tappet construction, including a cylindrical body and a plunger arranged therein for delningin conjunction with said cylindrical body a hydraulic compression chamber, means for electing a sub\ stantially complete seal between'said plunger and cylindrical body, and means for permitting a definite and predetermined leakage or escape of liquid from said hydraulic compression chamber.

Other objectsy features and advantages will f become apparent from the following description and appended drawings.

For thepurpose of illustrating the genus of 1936, serial No. 94,940

the invention, typical concrete embodiments are shown in the accompanying drawings in which:

Fig. 1 is a central vertical section of a tappet construction according to this invention;

Figs. 2 and 3 are transverse sections taken substantially on the lines 2-2 and 3-3 of Fig. l;

Fig. 4 is a section showing a portion of an internal combustion engine and showing a tappet such as illustrated in Figs. l and 3 interposed between the valve operating cam and a spring seated intake or exhaust valve;

Fig. 5 is a fragmentary view similar to Fig. 1

of a portion of a modifled form of tappet construction; and

Figs. 6, 17, 8 and 9 are Views similar to Fig. 1 of other modified forms of tappets constructed according to the -principles of this invention.

Referring to the drawings wherein like numerals are applied to like parts in the several views, and referring more especially to Figs. 1, 2 and 3, there is shown a hydraulic compensating tappet construction comprising a cylindrical body II, a plunger I2, a plunger spring I3, a coined or grooved valve I 4 in the form of a washer, a plain or at washer I5, an elastic but substantially incompressible washer or similar packing element I6. In the above washer-like elements I4, I5 and I6 are preferably, although not necessarily, maintained in position on a plunger means I2 by means of a packing retainer washer I'I and a packing spring I8.

The tappet body II is provided with an annular recess and one or more liquid admission ports 2l leading therefrom to the longitudinal bore 22 of the tappet body II. admitted through the recess 20. and port or ports 2| into the longitudinal bore 22, from a suitable source of liquid` supply, such as a lubricating system of an internal combustion engine. The

Liquid may be l lower end of the tappet body II is closed as indicated at 23 and is preferably provided with a hard wear-piece 24 adapted to engage the operating cam for an exhaust or intake valve of an internal combustion engine. The upper end of the cylindrical tappet body II is open for the reception of the plunger I2 and the latter is provided with a cylindrical portionv 25 adapted to make a free sliding t within the bore 22. The cylindrical portion 25 is providedv primarily for guiding purposes. The spring I8 is arranged in a slightly compressed condition between the outer headed end of the plunger I2 and the upper open end of the tappet body II for urging the plunger I2 outwardly with respect to the bottom of the bore 22. The plunger I2 is provided with an annular ange 26, the lower face of which, indicated at 21, is substantially normal to the axis of the plunger I2. The upper surface 28 of washer I5 is also a plain surface and the cooperating surfaces 21 of

ange

26 and 28 of washer I4 are both machined and polished so that when the washer is pressed upwardly by any material force leakage between the iiange 26 and washer I4 is prevented.

The space 30 within the bore 22 of the tappet body II, between the cylindrical portion 25 of plunger I2 and the valve member or washer I4 constitutes a preliminary or reserved liquid supply chamber for the tappet. The spane within the bore 22 of tappet body II between the valve member or washer I4 and the bottom of the bore 22 constitutes the hydraulic compression chamber 3| of the tappet. Expansion of the spring I3 tends to cause the plunger I2 to move outwardly with reference to the tappet body until the end of the plunger I2 contacts the end of the valve 33, as indicated in Fig. 4, and to cause end 23 of tappet body II to contact the valve operatingcam, or the upper end of the plunger I2 and th lower end of the tappet body II contact others parts of valve operating mechanism. Outward movement of the plunger with reference to the tappet body creates apartial vacuum condition within the compression chamber 3I and causes the upper surface 28 of the valve member of washer I4 to separate from the surface 21 of flange 26 and permits iiow of liquid from the preliminary or reserved chamber 30 to the hydraulic compression chamber 3| until the latter chamber is filled with liquid and the pressure becomes substantially equalized between the

chambers

30 and 3|.

The lower face of the valve member or washer I4 is provided with a spiral groove 32 leading from its interior periphery to its outer periphery as indicated in Figs. 1 and 3. In actual practice this groove is of very small dimensions, and may be of other form than spiral Where the desired resistance to ow can be obtained. The spiralling or otherwise lengthening of the groove 32 permits the same to be of suiiicient length to afford the desired resistance to flow of liquid from the interior to .the outer periphery of the valve member and still permit the groove 32 to be formed by mechanical processes with a desired accuracy so that a definite cross-sectional area and length of groove 32 may be had. This enables commercial production of grooved washers or valve members by coining or stamping processes so that denite leak-down rates can be obtained for large numbers oftappets with a result that uniform operation of all of the tappets will be obtained. The washer I5 is preferably composed of metal and has its upper and lower surfaces plain and parallel, and these surfaces are machined andrpolished so that undesired or inadvertent leakage between the surfaces thereof and the surfaces with which'they cooperate will not occur. The upper surface of the washer I5 cooperates with the grooved surface of the valve member of Washer I4 so that the groove 32 provides a' small cross-section passage preferably of extended length, the cross sectional area and length of this passage 32 being uniform for all tappets of the same type produced.

The washer I6 is preferably composed of a synthetic rubber or other elastic and substantially incompressible material, or may be formed amasar of a soft metal such as lead or soft alloys. The inner and outer peripheries of the Washer or packing element I6 are preferably substantially of the same dimensions as the washer elements I4 and I 5. The thickness of the washer I6, however, may be greater than that of either of the washers I 4 or I5. If desired, a downwardly flanged packing washer I1 having substantially the same inner and outer peripherial dimensions as the preceding washer-like elements and a light packing spring I8 may be employed for retaining the elastic packing washer I6, washer I5 and valve member I4 in position. The spring I8 is very light so that any material difference in pressure between the preliminary chamber 36 and the hydraulic compression chamber 3| will allow admission of liquid between the

cooperating surfaces

21 and 28 of the flange 26 on plunger I2 and the valve member I4, provided the lesser pressure occurs in the hydraulic compression chamber 3|. The spring I 8 and packing washer I1 may be omitted Aas illustrated in Fig. 9, later to be described.

During operation the tappet illustrated in Fig. l, is interposed in a valve operating mechanismr in the manner indicated in Fig. 4. Oil may be admitted through the annular recess 20 and ports 2| to the preliminary or reserve chamber 30, from the conventional lubricating system of the internal combustion engine. Plunger spring I3 holds the upper end of plunger I2 against the valve stem, or an operating part therefor, and the closed end 23 of the tappet body against the cam shaft', or part operated thereby. When the plunger spring I3 causes outward movement of the plunger with reference to the tappet body a partial vacuum condition will be created within the hydraulic compression chamber 3| and the valve member I4 will not be held in tight engagement with the shoulder 26 on plurrger I 2. Oil then flows between the

cooperatingolsurfaces

21 and 28 of the ange 26 on plunger I2 and the valve member I4 from the preliminary chamber 3U to the hydraulic compression chamber 3|. When the pressures are substantially equal in the

chambers

30 and 3|, the washer or valve element I4 will be brought into contact with the surface 21 of ange 26 by the action of the light packing spring I8. As the cam shaft lifts the tappet body, the pressure of the oil inthe hydraulic compression chamber 3| is increased on two faces of the packing element I6, the inner peripherial surface and the lower surface of the packing element I6, and will force the packing element against the wall of the bore 22 of the tappet body and against the washer I5. The expansion of the packing element I6 against the wall of the bore 22 of tappet body II will effect a seal between the packing element and the tappet body, and the pressure of the sealing element against the washer I5 will eii'ect a seal between these elements. This upward pressure is transmitted to the washer I5 forcing the latter into tight engagement with the valve member I4 so that no leakage can occur from the inner periphery of the valve member I4 to the outer periphery thereof except such leakage as is allowed by the spiral groove 32. This upward pressure likewise forces the smooth plain upper face 28 of the valve I4 against the corresponding face 21 on the flange 26 of plunger I2. Since the valve member I4 is pressed against theflange 26 by a force substantially equal to the entire load of the valve gear at the time of opening of the engine valve, a seal between the valve member I 4 and ange 26 is effected. When the engine valve is in closed position the' pressure holding the valve member I4 against the shoulder 26 is released so that oil can seep between the surfaces of the washer elements I4, I5, |6 and I1 and between the valve member I4 and the shoulder 26 so that a cleaning cycle is provided. The spiral groove 32, dueto its added length, may be used to provide for proper control of the leak-down rate of oil from the hydraulic compression chamber to the reserve supply chamber 3|) without having the cross-sectional area of the groove too small for manufacturing purposes. During lift of the engine valve the grooved face of the valve Vmember I4 is pressedagainst the at smooth face of the washer I by a force substantially equal to the entire load of the valve operating mechanism. In this manner, the engine valve will be elevated without appreciable lift loss except that provided for by the groove 32 which controls the leakdown rate of oil ow between the hydraulic compression chamber 3| and the preliminary or reserve chamber 30. y

As previously indicated the packing element or washer I6 is preferably composed of synthetic rubber, or other elastic but substantially incompressible material or expandable metal or alloy. The clearance between the inner periphery of the packing element I6 and the cylindricalportion of the plunger I2 surrounded thereby, is prefera'bly quite small so that the packing element I6 is maintained in a substantially confined condition between the plunger I2, the washer I5, the

I wall of. bore 22 of tappet body I I and the packing washer I1 on the oil within the hydraulic compression chamber 3I. With a packing washer in a substantially conned condition, elevation of the tappet by operating cam shaft therefor will increase the pressure within the hydraulic compression chamber 3| and cause the packing element I6 frictionally to grip the wall of the bore 22 of tappet body II so as to cause a lagging or retardation in movement of the plunger I2 relative to the tappet body II when forces acting axially upon opposite ends of the tappet are changed. The substantially incompressible packing element I6 will produce a mechanical hysteresis elect in that it causes a lagging orretardation of relative movement between the plunger IT! and tappet body II when forces acting axially upon the ends of the tappets are subjected to changes.l The magnitude of this effect may be controlled by varying the clearance between the inner peripherial surface of the packing element I6 and the cylindrical portion of plunger I2 which the packing element surrounds. This mechanical hysteresis effect of the packing element I6 will quiet the operation of the tappet and will substantially obviate any possibility of the tappet bouncing or chattering with reference to the operating cam therefor.

Reference may now be had to Fig. 4 which illustrates a tappet of the construction described relative to Fig. 1, interposed between a valve 33 of an internal combustion engine and an operating cam ,34 fixed to cam shaft 35. The operation of this arrangement will be clear from the above description of the construction shown in Fig. 1.

Referring to Fig. 5, a construction very Asimilar to that disclosed yin Fig. 1 is illustrated. In this construction the only modincaton is inthe plunger I2' and relates to the manner inlwhich the lower end of the packing spring I8 is connected to the plunger. In the construction shown in Fig. 5 an element 36 is press tted upon the reduced end 31 of plunger I2' in order to retain the lower end of packing spring I8 connected to the plunger I2 instead of clipped in a groove in the lower end of the plunger in the manner illustrated in Fig. 1. This construction, like that shown in Fig. 1, provides a resilient packing element I6 of substantially incompressible material adapted to be forcedinto. sealing contact with the wall of the bore of 'the tappet body II upon the occurrence of increased pressure in the hydraulic compression chamber 3| for substantially sealing the plunger I2' with respect to the tappet body II. Such increased pressures also cause the 'packing element I6 to be forced into sealing engagement with the washer I5 and the valve member I4 to effect a seal with the ange 26 of plunger I2. The coined or grooved lower surface of valve member I4 and the upper surfaceof the washer I5 are also brought into contact so that the spiral groove in the lower face of valve member I4l affords means for allowing only a denite and predetermined leakage or escape of oil from the hydraulic compression chamber 3 I. The construction of the remaining elements and their arrangement is the same as that illustrated in Fig. 1.

, Reference `may now be had to Fig. V6 which illustrates a modified form of tappet construction embodying the principles of the present invention, this construction including a cylindrical tappet body 4| provided with a bore 42, which aifords the shoulder 43 for supporting a separate cylinder 44 adapted to be received within the upper end of the bore 42. j

The tappet body 4I is provided with an annular recess 45 and an admission port 46 and is otherwise of substantially the same construction as that disclosed inthe embodiment showing in Figs.

1 and 5. 'I'he separate cylinder 44 is provided with a cylindrical bore 41 and a reduced and bored boss portion 50 in which has been press tted a suction tube 5| and a valve retaining cage 52.v

the cage 52 is provided with an oil passage 54.

The separate cylinder 44 preferably makes a drop or sliding fit within the upper end of the bore 42 so that air may be vented from the preliminary or reserve liquid supply chamber 55 formed by that part of the bore 42 which lies below the separate cylinder 44. The tappet plunger 56 makes a loose or sliding fit within the bore 41 of separate cylinder 44. A cylindrical washer member 51 makes a similar t'within the bore 41 of separate cylinder 44 and is arranged within the latter b'ore immediately below the' plunger 56. An elastic packing washer 60 and a packing retainer washer 6I are arranged within the bore 41 below the plunger 56 and washer 51 in the order named. A coil spring 62 is interposed between the boss portion 5I! of separate cylinder 4 4 and the packing retainer washer 6I for extending the plunger 56 outwardly with reference to the sepa'- rate cylinder until the upper end of the plunger contacts one element of a valve operated gear while the closed end of the tappet body contacts ing washer 60 and washer 51. That portion of the bore 41 of separate cylinder above the nonreturning valve 53 and below the

Washer elements

51, 66 and 6| constitutes the hydraulic compression chamber 64 of the tappet.

During operation of this tappet construction, oil or other liquid under pressure is admitted through theannular recess l5 and port 46 to the preliminary or reserve supply chamber 5,5.

. The plunger spring 62 causes extension of plunger 56 until the latter contacts one valve operating part and the closed end of the tappet body 4| contacts another valve operating part. Outward movement of the plunger 56 creates a partial Vacuum condition within the hydraulic compression chamber 64 causing the valvev 53 to lift from its seat and liquid medium to be drawn upwardly through the suction tube 5| Ainto the hydraulic compression chamber 64 of the tappet. When an engine valve is lifted by the tappet, the increased pressure. within the hydraulic compress-ion chamber 64 is exerted upon the .inner periphery of the elastic but substantially incompressible packing element 66 and upon the lower surface of the latter, causing the material of the packing to flow outwardly and provide a seal between th-e packing andthe bore 41 of the separate cylinder 44. The increased pressure exerted by the liquid medium within the hydraulic compression chamber causes the adjacent sur-v faces of washer 51 and the elastic packing element 6|! to be pressed together and the upper surface of washer 51 and the lower surface of plunger 56 likewise to be brought into intimate contact. 'I'he surfaces are pressed together by a force substantially equal to the entire load of the valve operating gear at the time of opening of the engine valve. 'I'he leak-down rate between th-e plunger and separate cylinder is controlled by the lower surface ofthe plunger 56 and the upper surface of the washer 51, one of the surfaces either being grooved as indicated as 32 in ducing a lagging or retardation of movement of the'plunger with reference to the separate cylinder when axial forces directed against opposite fends of the tappet are varied as in the previously described constructions. The'non-action ball vvalve 53 vis gravity and 'inertia actuated as well as by differential fluid'pressures to lcause its return to and maintenancezin seatedposition during lift of the tappet.

Referring to Fig. 7,' a tappet very similar in construction to that shown lin Fig. 6 is illustrat-ed.- In this construction the plunger 56', corresponding to the plunger 56 of the previously described embodiment is provided with a reduced end portion 65 adapted to contacta valve stem or other valve operating part for an exhaust or intake'valve of an internal combustion engine. An abutment sleeve 66 is threaded to the upper end of the separate cylinder 44', corresponding to the separate cylinder 44 of the previously described embodiment, and the abutment sleeve 66 is spaced a considerable distance from the reduced portion 65 of plunger 56. The abutment sleeve 66 limits outward movement of the plunger with reference to a separate cylinder so that in the event that `an engine valve becomes stuck in open position the plunger cannot follow the stuck valve a suicient distance to cause breakage of the latter or of the cylinder head of the engine. The remaining parts shown in Fig. '7 correspond with like parts shown in Fig. 6 and are given the same numerals. i i Reference may now be had to Fig. 8 which discloses a further modified form of tappet construction. This construction' includes a cylin-A dricalV body portion 10 provided with a longitudinal b ore 1| and a closed end 12 and is further provided with an annularrecess 13 and one or more liquid admissionports 14. A substantially hollow plunger` 15 is received in the bore 1| of tappet body 18. The plunger 15 is provided with an annular recess 16 which communicates through port 14 with the annular recess 13 so that liquid under pressure or oil from the lubrieating system of internal combustion engine may be supplied to the annular recess 16 which constitu-es the preliminary or reserve oil supply chamber of the tappet. This tappet construction is designed primarily for overhead type of engine valves and the cylinder 15 is provided with an inwardly directed ange 11 forguiding a push rod, indicated at 18, and preventing the latter from jumping lits seat. A substantially spherical seat 8U is provided at the upper end of a threaded member 8| which is threaded into the lower end of plunger 15 and provided with a head portion 82 adapted to hold an elastic but substantially incompressible packing element 83 in assembled relationwith reference to the plunger 15. The packing elment 83 is downwardly ilanged as indicated at 84 at the outer periphery thereof. The seat member 8| is axially lbored as indicated at 85 for lightness. 'I'he seat member 8| is also provided with a downwardly directed boss portion 86 adapted to contact the lower closed end 12 of the tappet bodv 1| in the event of failure of oil supply so that after cillin the preliminary or reserve supply chamber 16 has been exhausted, the tappet will still cause operation of the engine valve although with some lift loss. Axially directed peripherial passages 81 are provided at the lower end of the plunger 15 for permitting passage of oil or other liquid under pressure past the lower end of the piston from the preliminary or reserve liquid supply chamber 16 to the hydraulic compression chamber 90 formed by that portion of the bore 1| between the plunger 15 and the'lower closed end 12 of the tappet body 10. A plunger spring 9| is disposed about the boss portion 86 and is lcompressed from free length by an amount only a slightly more than is needed for compensation purposes'so that the plunger will not follow a stuck engine valve a suicient distance to'cause breakage by forcing the latter intoA a cylinder a suflicient distance to cause .breakage of the valve or of an engine piston.

'Ihe opposite ends of the plunger spring 9| abut the seatmember 8| and the lower closed end 12 of tappet body 10 in order vto force the plunger 15 outwardly with reference to the tappet bo'dy for compensation purposes.

Liquid under pressure or oil from the lubricating system of the engine is admitted to the annular recess 13 and inlet port 14 through the preliminary or reserve supply chamber 16. The plunger spring 9| forces the plunger 15 outwardly until the seat 80 is in contact with the lower end of the push rod 18, and the closed end 12 is brought into contact with the operating cam of the engine valve operating mechanism. Any movement of the plunger 15 outwardly with reference to the tappet body 10 creates a partial vacuum condition within the hydraulic compression chamber 90 and relaxes the pressure on the lower end of the elastic but substantially incompressible packing element 83 allowing oil or other liquid to pass from the preliminary or reserve supply chamber 16 through the peripherial grooves or passages 81 and past the elastic packing 83 to the hydraulic compression chamber 90. As the valve operating cam starts to lift the tappet increased pressures within the hydraulic compression chamber act on the lower surface of the downwardly directed flanged portion 84 of the elastic packing 83 and cause a flowing of the material of the elastic packing until the outer periphery thereof is brought into sealing relation with the bore 1| of tappet body 10. Thus in the present construction the elastic packing not only serves to provide a seal between the plunger and the bore of the tappet body but also provides a non-return valve contr lling the admission of oil or other liquid under gressure to the hydraulic compression chamber. The elastic but substantially incompressible packing 83 is substantially confined by the plunger 15, the head portion 82 of the seat member 8|, the wall of the bore 1| of tappet body 10 and the oil orother liquid in hydraulic compression chamber 90 so that the elastic packing 83 affords the same mechanical hysteresis effect in causing a lagging or retardation of movement of the plunger relative to the tappet body as in the previously described embodiments.

' Within the bore |0| are disposed a pair of pressed metal cup-like members |06 and |01, the member |06 being arranged in inverted positionso that the open ends of the cup-like members face one another. The cup-like member' |06 constitutes a part of the plunger of the tappet construction while the cup-like member |01 forms the separate cylinder. A stem member |08 is riveted to the bottom of the inverted cup-shaped member |06 as indicated at |0 and forms a part of the plunger structure. The stem member |08 is provided with a flange the lower face of which is disposed in a plane transverse to the axis of the stem member |08. The stem member |08 carries a washer-like valve member, ||2 and a washer-like elastic but substantially incompressible packing element ||3 loosely secured inworking position by means of a retaining washer ||4 pressed into the lower reduced end of stem. |08. The tappet body |00 is provided with an annular recess ||5 outside the bottom portion of the cup-like separate cylinder |01 and this recess communicates through the openings H6 to the exterior periphery of the tappet body, the openings I6 being adapted to drop partiallyY below the lower end of the tappet guide for ventilation purposes and for lightening the tappet construction. In the event of failure of the oil supply, the lower end oi the stem |08 will abut the bottom of the separate cylinder member |01 after the liquid or oil in the preliminary chamber |05 has been exhausted so that the tappet will continue to lift the engine valve, although with some lift loss. A plunger spring ||1 engages suitable recesses in the inner peripherial surfaces of the open ends of the clip-like members |06 and |01 to extend the plunger outwardly with reference to the tappet |00. The preliminary or reserve supply chamber for Aoil or liquid comprises a recess |05, the hollow interior of the cuplike plunger |06 not occupied by the stem |08,

the portion of the hollow interior of the cup-like separate cylinder |01 lying above the flange on stem |08 and valve member ||2 and the space within the bore lying between the plunger and separate cylinder not occupied by the stem |08 and the spring ||1. As in the previously described embodiment, the plunger spring ||1 tends to extend the plunger |06 outwardly with reference to the tappet body until the upper end of the plunger contacts a valve operating part while the lower end of the tappet body |00 contacts another valve operating part. This tends to create a partial vacuum condition'within the hydraulic compression chamber 20 located in the bottom portion of the -separate cylinder |01 so that the superior oil pressure Within the reserve supply chamber |05 will force the valve member ||2 from its seat and cause fiow of oil or other liquid under pressure from the reserve or preliminary chamber and into the hydraulic compression chamber until the pressure within the chambers are substantially equalized. As the engine valvel operating cam lifts the tappet, the increased pressure within the hydraulic compression chamber |20 acts 'upon the lower face of the packing element ||3 and upon its inner periphery to flow the material of the packing element outwardly against the bore of the separate cylinder |01 thus sealing the packing element with reference to the separate cylinder and with reference to valve member ||2. The pressure against the lower surface of the packing element I3 forces the valve member l |2 upwardly against the flange so that nearly a complete seal is established between the valve member ||2 and flange member One or the other of the cooperating surfaces of the flange and valve member ||2 are either grooved as indicated in the embodiment shown in Figs. 1 and 5 or left in a slightly roughened condition until the proper leak-down 'rate is obtained between these elements in order to compensate for the lengthening of valve operating parts due to expansion under heat. In this construction the unit comprising the plunger, plunger spring and separate cylinder structure and contained parts is reversible in the tappet body so that the tappet can also be employed in conjunction with an overhead valve operating cam shaft. Also, if desired, a Sylphon bellows may be used in place of the plunger spring ||1 for a self-contained tappet.

In the construction shown in Fig. 9 such elements as a plain washer and a packing spring washer and packing spring |1 and I8 of the embodiment shown in Figs. 1 and 5 are omitted. In the construction shown in Figs. l and 5, essentially the same valve and sealing element construction should be employed as in the case of the embodiment shown in Fig. 9.

In the embodiment illustrated in Fig. 9 the valve element ||2 is provided with a passage |2| extending therethrough in an axial direction so that when the pressure is relieved in the hydraulic compression chamber |26, the valve element may be readily separated from the ange IH and from the sealing element H3 in order to readily effect a cleaning cycle when the engine valve is on its seat. A vent opening 422 is bored through the wall of the plunger element 06 near the upper end thereof to prevent trapping of substantial quantities of air or gas within the hollow interior of the plunger |06.

In all of the illustrated embodiments, the preliminary or reserve air separation chamber 'is vented to atmosphere either through clearance between the plunger and the bore of the tappet body as in the embodiment shown in Figs. 1 to 5, 8 and 9 or through clearance between the separateY cylinder and the bore of the tappet body as in the case of the embodiment shown in Figs. 6 and '7. The elastic packing elements are forced radially outwardly by owing the material thereof in that direction in order to seal the plunger with reference to its cylinder, but when the engine valve is on its seat to permit air or gas to ilow by gravity from the highest point of the hydraulic compression chamberY past the plunger to the preliminary or reserve chamber in the embodiments shown in Figs. 1 to 5, 8 and 9 or directly to atmosphere in the embodiments shown in Figs. 6 and 7. Av mechanical hysteresis effect is afforded by all of the.illustrated embodiments due to forcing the elastic but substantially incompressible packing-to flow the material thereof outwardly against the wall of its confining cylinder, the packing otherwise being substantially conned by the plunger element or elements carried thereby and the oil lin the hydraulic compression chamber of the tappet so as to produce a. lagging or retardation in movement of the plunger with reference to the separate cylinder when axially directed forces against the end of the tappet are changed. In .each of the illustrated embodiments provision is made for limiting travel inwardly of the plunger so that operation of the engine valve 45 will be had, although with some lift loss, in theevent ofv failure: of oil supply and after oil in the preliminary or reserve supply chamber has been .-.-.exhausted. In the embodiment shown in Figs. 1 and 5, the lower end of the plunger l2 or the 50 element 36 abuts the closed end 23 for limiting .inward movement oi the plunger with reference to the tappet body. In the embodiment shown `in Figs. 6 and 7 the plunger and elements carried thereby have but a limited movement nwardly with reference to the

separate cylinders

44 or 44. In the construction shown in Fig. 8 the boss portion 86 and in the embodiment shown -in Fig. 9 the lower end of the stem member |08 serve the same ends.

The specic application of a lead or other soft metal and therefore ductile packing washer in a tappet of the construction herein described forms 'the subject matter of our copending United States application for patent for improvements in Tap- 55 pet construction iiled July 21, 1939, and serially numbered 285,766, the same being a division of Ethe present application. K, As many changes could be made in the above construction, and many apparently widely diier- 70 ent embodiments of this construction could be had without departing from the scope thereof, it is intended that all matter contained in the above description or showing shall be interpreted `as illustrative and not in a limiting sense.

What is claimed is:

ber-like substance substantially confined by said 1. In a valve tappet, the combination of a cylindrical body provided with a longitudinal bore, said body being closed at one end and open at the other, a plunger disposed in said bore and means including a yieldable but substantially incompressible element composed of rubber-like substance for causing a lagging or retardation in movement of said plunger relative to said cylindrical body'when forces acting axially upon opposite ends of said tappet are changed.

2. In a hydraulic valve tappet, the combination of a cylindrical body provided with a longitudinal bore, said body being closed at one end and open at the other, a plunger disposed in said bore and in conjunction with said cylindrical body dening a hydraulic compression chamber between the plunger and the closed end of said cylindrical body, means for admitting liquid into said cylindrical body, and resilient means for extending said plunger outwardly with respect to said cylindrical body, of means including a yieldable but substantially incompressible element composed of rubber-like substance in a substantially confined condition for causing a lagging or retardation in movement of said plunger relative to said cylindrical body when forces acting axially upon opposite ends of said tappet are changed.

3. In a hydraulic valve tappet, the combination of a cylindrical body provided with a longitudinal bore, said body being closed at one end and open at the other, a plunger disposed in said bore and in conjunction with said cylindrical body dening a hydraulic compression chamber between the plunger and the closed end of said cylindrical body, means for admitting liquid to said cylindrical body, and resilient means for extendingsaid plunger outwardly with respect to saidcylin'drical body, of means including a yieldable but substantially incompressible elementcomposed of rubplunger, said hydraulic compression chamber and said cylindrical body for causing a lagging or retardation in movement of said plunger relative to said cylindrical body when forces acting axially upon opposite ends of said tappet are changed.

4. A hydraulic valve tappet, comprising a cylindrical body provided with a longitudinal bore, said body being closed at one end and open'at the other, a plunger disposed in said bore and in conjunction With said cylindrical body deiining a hydraulic compression chamber, means for admitting liquid into said cylindrical body and resilient means for extending said plunger outwardly with respect to said cylindrical body, said plunger including at one end a cylindrical guide portion making a free sliding ilt in the bore of said cylindrical body, and valve means carried by the opposite end of said plunger and including a yieldable but substantially incompressible element shiftable axially of the plunger substantially conilned by the plunger, cylindrical body and the hydraulic compression chamber for eilecting a seal between said plunger and cylindrical body.

5. A hydraulic valve tappet, comprising a cylindrical body, provided with a longitudinal bore, ,said body being closed at one end and open at the other, -a plunger disposed in said bore and in conjunction With said cylindrical body .dening a hydraulic compression chamber, means`for admitting liquid into said cylindrical body and resilient means for extending said plunger outwardly with respect to said cylindrical body, said plunger including 'an annular flange providing a plain surface normal to the axis of said plunger, a plain surface valve disc positioned to abutat one face thereof the plain surface of said ange to provide a check valve, the other plain surface of said valve disc being provided with a groove of small cross-section and extended length, a second plain surface disc positioned to abut the grooved surface of said valve disc to complete a small open at the other, a plunger disposed in said bore and in conjunction with said cylindrical body defining the hydraulic compression chamber between the plunger and the closed end of said cylindrical body, means for admitting liquid into said cylindrical body, and resilient means for extending said plunger outwardly with respect to said cylindrical body, of means including a owable but substantially incompressible element for substantially preventing ow of liquid out of said hydraulic compression chamber, and means loosely mounted on said plunger and ,providing for a definite and predetermined escapement of liquid out of said hydraulic compression chamber.

'7. In a hydraulic valve tappet, the combination with a cylindrical body provided with a longitudinal bore, said body being closed at one end andopen at the other, a plunger disposed in said bore and in conjunction with said cylindrical' body defining the hydraulic compression chamber between the plunger and the closed end of said cylindrical body, means for admitting liquid into said cylindrical body, and resilient vmeans for extending said plunger outwardly with respect to said cylindrical body, of means including a yieldable but substantially incompressible element providing a seal between the plunger and cylindrical body and substantially preventing ow of liquid out of said hydraulic compression chamber, and means loosely mounted on said plunger and providing for a definite and pre-determined escapement of liquid out of said hydraulic compression chamber.

8. In a hydraulic valve tappet, the combination with a cylindrical body provided with a longitudinal bore, said body being closed at one end and open at the other, a plunger disposed in said bore and in conjunction with said cylindrical body defining the hydraulic compression chamber bet een the plunger and the closed end of said cylindrical body, means for admitting liquid into said cylindrical body, and resilient means for extending said plunger outwardly with respect to said cylindrical body, washer-like element of yieldable but substantially incompressible material and providing a seal between the plunger and cylindrical body for substantially preventing flow of liquid out of said hydraulic compression chamber and means loosely mounted on said plunger and providing for a deiinite and pre-determined escapement of liquid out of said hydraulic compression chamber.

9. In ahydraulic valve tappet, the combination with a cylindrical body provided with a longi-` tudinal bore, said body being closed at one end .and open at the other, a plunger disposed in said bore and in conjunction with said cylindrical body dening the hydraulic compression chamber between the plunger and the closed end of said of means including a cylindrical body, means forv admitting liquid into said cylindrical body, and resilient means for extending said plunger outwardly with respectto said cylindrical body, of means including a washer-like element of yieldable but substantially I incompressible material and providing a seal between theplunger and cylindrical body for substantially preventing iiow of liquid out of said hydraulic compression chamber and means including a substantially rigid washer-like element 10 provided with a small cross-sectioned groove in one face thereof extending from its inner to its outer periphery and a second substantially rigid washer-like element provided with a iiat surface adapted to contact the grooved surface of said 15 first named substantially rigid element providing for a definite and predetermined escapement of liquid out of said hydraulic vcompression chamber.

l0. In a hydraulic valve tappet, the combination with a cylindrical body provided with a lon- 2i) gitudinal bore and closed at one end, a plunger disposed in said bore and in conjunction with said cylindrical body dening a hydraulic compression chamber between the plunger and the closed end of said cylindrical body, of means 25 including a flowable but substantially incompressible element for substantially preventing ow of liquid out of said hydraulic compression chamber, and means loosely mounted on said plunger and providing a deiinite and predetermined escape- 30 ment of liquid out of said hydraulic compression chamber.

11. In a hydraulic valve tappet, the combination with a cylindrical body provided with a longitudinal bore, said body being closed at one end 3s and open at the other, a plunger disposed in said bore and in conjunction with said cylindrical body defining a hydraulic compression chamber between the plunger and the closed end of said cylindrical body, means for admitting liquid into 4b said cylindrical body, and resilient means for extending said plunger outwardly with respect to said cylindrical body, of valve means including means for effecting a substantially complete seal between4 said plunger and said cylindrical body 45 and including means for limiting to a denite and predetermined amount escape'of liquidifrom said hydraulic compression chamber.

12. In combination, a hydraulic valve tappet interposed between an operating cam and an en- 50 gine valve and comprising a cylindrical body provided with a longitudinal bore, said body being 4 closed at one end and open at the other, a plunger disposed in said bore and in conjunction with said cylindrical body dening a hydraulic com- 55 pression chamber between the plunger andthe closed end of said cylindrical body, means for admitting liquid into said cylindrical body, resilient means for extending said plunger outwardly with respect to said cylindrical body, and 60 valve means arranged between the means4 for admitting liquid into said cylindrical body and said hydraulic compression chamber, said valve means including means effecting a substantially complete seal between said plunger and said cylindrical body to prevent escape of liquid from said hydraulic compression chamber and including means for limiting to a definite andt predetermined amount escape of liquid from said hydraulic compression chamber when the engine valve is open.

13. In a hydraulic valve tappet, thefcombinaend and open at the other, a plunger disposed in said bore and in conjunction with said cylindrical body dening a hydraulic compression chamber between the plunger and the closed end of said cylindrical body, means for admitting liquid into said cylindrical body, and resilient means for extending said plunger outwardly with respect to'said body, of non-return valve means including a yieldable element shiftable relative to the plunger, said yieldable element providing a seal between the plunger and cylindrical body and providing a portion of said non-return valve means, said non-return valve means permitting passage of liquid into said hydraulic compression Vchamber but substantially preventing flow of liquid 'out of said hydraulic compression chamber.

14. Inn-a hydraulic valve tappet, the combination with a cylindrical body provided wth a longitudinal bore, said body being closed at one end and open at the other, a plunger disposed in said bore and in conjunction withsaid cylindrical body defining a hydraulic compression chamber and a liquid supply chamber, means for admitting liquid into said cylindrical body, and means for extending said plunger outwardly with respect to said cylindrical body, of non-return valve means including a yieldable element shiftable relative to the plunger,.said yieldable element providing a seal between the plunger and cylindrical body and providing a portion of said non-return valve means, said non-return valve means permitting passage of liquid from said supply chamber to said compression chamber but substantially preventing ilow of liquid from said compression chamber to said supply chamber. v

15. In a hydraulic valve tappet, the combination with a cylindrical body provided with a longitudinal bore, said body being closed at one end and open at the other, a plunger ldisposed i in said bore and in conjunction with said cylindrical body defining a hydraulic compression chamber between the plunger and the closed end of said cylindrical body, means for admitting liquid into said cylindrical body, and resilient means for extending said plunger outwardly with respect to said cylindrical body, of non-return valve means including a yieldable element, said yieldable element providing a seal between the plunger and cylindrical body and providing a portion of said non-return valve means, said nonreturn valve means permitting passage of liquid into said compression chamber but substantially preventing iiow of liquid out of said compression chamber, said non-return valve means also including a pair of disc-like elements having abutting plain surfaces, one of such surfaces being provided with a groove of relatively small crosssectional area but relatively long length for limiting to a slight amount leakage outwardly from the hydraulic compression chamber when said non-return valve means is closed.-

A16.1n a hydraulic valve tappet, the combina;

tion with a cylindrical body provided with a longitudinal bore, said body being closed at one end and open at the other, a plunger disposed in said bore and in conjunction with said cylindrical boda" defining a hydraulic compression chamber and va 'liquid supply chamber, means for admitting liquid intosaid cylindrical body,

and resilient means for extending said plunger outwardly with respect to said cylindrical body, of non-return valve means including a yieldable element, said yieldable element providing a seal between the plunger and cylindrical body and providing a portion of said non-return valve amasar means, said non-return valve means permitting passage of lliquid from said supply chamber to said compression chamber but substantially preventing return ow of liquid from said compression chamber to said supply chamber, said non-return valve means also including a pair of disc-like elements having abutting plain surfaces, one of such surfaces being provided with a groove of relatively small cross-sectional area and relatively Vlong length for limiting to a small amount leakage from said hydraulic compression chamber to said liquid supply chamber when said non-return valve means is closed..v

17. In a hydraulic yalve tappet, the combination with a cylindrical body provided with a longitudinal bore, said body being closed at one end and openat the other, a plunger disposed in said bore and in conjunction lwth said cylindrical ,erI and cylindrical body, and providing a portion of said non-return valve means, said non-return valve means permitting passage of liquid into said hydraulic compression chamber but substantially preventing return ow of liquid out of said compression chamber, said means including a washer-like element provided with a plain surface in which is formed a small cross-sectional groove extending spirally from its inner to its outer periphery for limiting to a slight amount leakage from said hydraulic compression chamber when said non-return valve means is closed.

18. In a hydraulic valve tappet, the combination with a cylindrical body provided wth a longitudinal bore, said body being closed at one end and open at the other, a plunger disposed in said bore and in conjunction with said cylindrical body defining a hydraulic compression chamber anda liquid supply chamber, means for admitting liquid into said cylindrical body, and resilient means for extending said plunger outwardly with respect to said cylindrical body, of non-return valve means including a yieldableelement, said yieldable element providing a seal between the plunger and cylindrical body and providing a portion of saidnon-return valve means, said nonreturn valve means permitting passage of liquid from said supply chamberv to saidhydraulic compression chamber but substantially preventing return iiow of liquid from said hydraulic compression chamber to said supply chamber, said means alsolincluding a Washerlike element provided With a plain surface in which is formed a small crosssectioned groove extending spirally from'its inner to its outer periphery for limiting to aslight amount leakage from said hydraulic compression chamber tosaid liquidfsupply chamber when said non-return valve means is closed.

v 19. In combination, a hydraulic valve -tappet interposed between an operating cam and an engine valve and comprising a` cylindrical body provided With a longitudinal bore, said body being closed at one end and open at the other, a plunger disposed in said bore and in conjunction with said cylindrical body defining a hydraulic compression chamber between the plunger and the closed end of the cylindrical body, means for admitting liquid into said cylindrical body. and resilientmeans for extending said plunger outwardly with ree speci; to said cylindrical body, of check valve means for controlling the ow of liquid to and from said hydraulic compression chamber, said check valve means including a yieldable but substantiaily incompressible valve element shiftable relative to the plunger arranged in a. substantially conflned condition by said piston, said cylindrical body, and the liquid in said hydraulic compression chamber, said valve element having an outside diameter substantially equal to that of said plunger. 5

CARL VOORHIES. HARRY E. VOORHIES.