US2227288A - Tappet construction - Google Patents

Description

1940. c. VOORHIES EIAL 2,227,238

TAPPET CONSTRUCTION Original Filed Aug. 3, 1936 2 Sheets-Sheet 1 Dec.3l, 1940. c. VOORHIES ET AL TAPPET CONSTRUCTION Original Filed Aug. 3, 1956 2 Sheets-Sheet 2 Patented Dec. 31, 1 940 TAPPET CONSTRUCTION Carl Voorhies and Harry E. Voorhies, Detroit, Mich, assignors to Eaton Manufacturing Company, Cleveland, Ohio, a corporation of Ohio Original application August 3, 1936, Serial No. 94,040. Divided and this application July 21,

1939, Serial No. 285,766

4 Claims. (01. 123-90) This invention relates to automatic compenbecome apparent from the following description sating tappets for operating such parts as intake and appended drawings. or exhaust valves of internal combustion engines, For the purpose of illustrating the genus of and more especially relates to improvements in the invention, typical concrete embodiments are the construction and arrangement of tappets of Shown in the a c mpa yi d aw n s in whi h such character, and is a division of our appli- Fig. 1 is a central vertical section of a tappet cation for Letters Patent of the United States construction according to this invention; for improvements in Tappet construction, filed Figs. 2 and 3 are transverse sections taken August 3, 1936, serial No. 94,040 now Patent No. substantially on the lines 2-2 and 3-3 of Fig. 1; 2,185,991, issued Jan. 2, 1940. Fig. 4 is a section showing a portion of an in- The principal object of the invention is to ternal combustion engine and showing a tappet improve the automatic compensating mechanism uch'as illus r ted in F 1 to 3 inte p ed eof tappets especially adapted for operating movatween the valve operating cam and a spring ble parts of internal combustion engines. Seated intake exhaust Valve; Another object is to provide in a device of the 5 is a fragmentary V w Similar o F 1 above character a novel check valve construction of a portion of a m ifi f rm f pp nand arrangement or such nature that the check struction; an

valve means is closed by a force substantially Figs. 6 and 7 a e v e s m ar o 1 Of equal to the force exerted by the engine valve other modified forms of tappets constructed acoperating gear when the engine valve is open. cording to the principles of this invention. r A further object is to provide a novel plunger Referring o t e drawings w r n like nuconstruction for hydraulic compensating tappets merels are pp t like p s n the several which includes means providing a seal between views, and referring e e pe y to Figs. 1, 2 the plunger and its cylinder, and an inlet port and 3. there s sh w a y a l mp nsa in and a check valve means for the hydraulic comeppe s u t C mp ng a cylindrical pensating chamber of the tappet. y a p u a plunger spring l3, a It is also an object of the invention to provide coined or o ved alve I in the formof a for a uniform rate of leakage from the hydraulic washer, a plain or fiat washer l5, and a yieldcompression chamber of the tappet and to employ able but substantially incompressible washer or o a single element adapted to abut a plain surface similar packing element l6 formed or a ductile for controlling such leak-down rates so that a met ln the b ve Wa e elements 80 single element may be accurately manufactured nd s a e preferably, although n t n c a y. by a coining or stamping process. maintained in position on the plunger I2 by Another object is to provide a system of conmeans 0! 'D a e Was er I"! and a u struction which obviates the necessity of selective packing spring I8.

or other accurate fitting of plunger parts with he t pp t y H is provided with an annular respect to the cylinder therefor. recess 20 and one or more liquid admission ports A still further object of the invention is to 2! leading h r f om t the l n i udinal bore 22 provide, in a tappet construction including a or the tappet body q d y be dmit ed cylindrical body and a plunger arranged therein; through e e s 20 and Dori; P ts into for a mechanical hysteresis effect, 1. e. a lagging e longitudinal bore from a uitab e source or retardation of the movement of the plunger of liquid S pp y, S c s a lubricating ystem of relative to its cylinder when forces acting axially an n l Combustion n e lower end upon the tappet ends are changed. oi. the tappet body II is closed as indicated at 23 Another object is to providejin a tappet conand is preferably provided with a hard wearstruction, including a cylindrical body and a Piece 4 a apted to engage the operat ng cam plunger arranged therein for defining in onfor an exhaust or intake valve of an internal Junction with said cylindrical body a hydraulic combustion engine- The upper d 1 the cylincompression chamber, means for efiecting a subdrioal tappet body II is p f h reception stantially complete seal between said plunger 0f the Plunger l1 a the letter is provided with and cylindrical body, and means for permitting a cylindrical portion 25 adapted to make a free a definite and predetermined leakage or escape sliding fit within the bore 22. The cylindrical of liquid from said hydraulic compression portion 25 is provided primarily for guiding purchamber. poses. The spring I8 is arranged in a slightly N Other objects, features and advantages will compressed condition between the outer headed g end of the plunger l2 and the upper open end of the tappet body II for urging the plunger l2 outwardly with respect to the bottom of the bore 22. The plunger I2 is provided with an annular flange 26, thelower face of which, indicated at 21, is substantially normal to the axis of the plunger |2. The upper surface 28 of washer I5 is also a plain surface and the cooperating surfaces 21 of flange 26 and 28 of washer I41 are both machined and polished so that when the washer is pressed upwardly by any material force leakage between the flange 26 and washer I4 is prevented.

The space 30 within the bore 22 of the tappet body between the cylindrical portion 25 of plunger l2 and the valve member or washer |4 constitutes a preliminary or reserved liquid supply chamber for the tappet. The space within the bore 22 of tappet body between the valve member or washer l4 and the bottom of the bore 22 constitutes the hydraulic compression chamber 3| of the tappet. Expansion of the spring |3 tends to cause the plunger |2 to move outwardly with reference to the tappet body until the end of the plunger |2 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 operating cam, or the upper end of the plunger |2 and thelower end of the tappet body contact other parts of valve operating mechanism. Outward movement of the plunger with reference to the tappet body creates a partial vacuum condition within the compressionchamber 3| and causes the upper surface 28 of the valve member or washer M to separate from the surface 21 of flange 26 and permits flow 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 flow can be obtained. The spiralling or otherwise lengthening of the groove 32 permits the same to be of sufficient 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 definite leakdown rates can be obtained for large numbers of tappets 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 and polished 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 or washer |4 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 is composed of a soft metal such asv lead or soft alloys, such metal inherently having,

of course, a high degree of ductility. The inner ing washer l6, washer i5 and valve member H in position. The spring 3 is very light so that any material difference in pressure between the preliminary chamber 30 and the hydraulic compression chamber 3| will allow admission of liquid between the cooperating surfaces 21 and 28 of the flange 26 on plunger l2 and the valve member I4, provided the lesser pressure occurs in the hydraulic compression chamber 3|.

During operation the tappet illustrated in Fig. l, is interposed in a valve operating mechanism 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 l3 holds the upper end of plunger l2 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 l3 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 M will not be held in tight engagement with the shoulder 26 on plunger |2. Oil then flows between the cooperating surfaces 21 and 28 of the flange 26 on plunger l2 and the valve member M from the preliminary chamber 30 to the hydraulic compression chamber 3| When the pressures are substantially equal in the chambers 30 and 3|, the washer or valve element M will be brought into contact with the surface 21 of flange 26 by the action of the light packing spring l8. As the cam shaft lifts the tappet body, the pressure of the oil in the hydraulic compression chamber 3| is increased on two faces of the packing element 6, the inner peripheral surface and the lower surface of the packing element I6, and will tend to radially expand the packing element and force it outwardly against the wall of the bore 22 of the tappet body and will also force it against the washer |5.. The ductility of the material from which the packing element is constructed is such that the packing element IE will actually be expanded into contact with the wall of the bore 22 of tappet body M if not already in contact therewith, and will be maintained in firm contact therewith if already in contact with the wall, so as to effect a seal between the packing element and the tappet body, and the pressure of the sealing element against the washer l5 will effect a seal between these elements. This upward pressure is transmitted to the washer |-5 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 [4 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 |4 against the corresponding face 21 on the flange 26 of plunger |2. since the valve member I4 is pressed against the flange 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 14 and flange 26 is effected. When the engine valve is in closed position the pressure holding the valve member l4 against the shoulder 26 is released so that oil can see'p between the surfaces of the washer draulic compression chamber to the reserve supply chamber 30 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 member I4 is pressed against the flat smooth face of the washer l5 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 leak-down rate of oil flow between the hydraulic compression chamber 3| and the preliminary or reserve chamber 30.

As previously indicated the packing element or washer I5 is composed of yieldable ,or expandible metal of alloy of highly ductile character. The clearance between the inner periphery of the packing element l6 and the cylindrical portion of the plunger l2 surrounded thereby, is preferably quite small so that the packing element I6 is maintained in a substantially confined condition between the plunger I2, the washer 15, the wall of bore 22 of tappet body H and the packing washer I! on the oil within the hydraulic compression chamber 3|.

With the packing washer IS in a substantially confined 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 l5 frictionally to grip the wall of the bore 22 of tappet body H so as to cause a lagging or retardation in movement of the plunger (2 relative to the tappet body II when forces acting axially upon opposite ends of the tappet are changed. The packing element IE will produce a mechanical hysteresis effect in that it causes a lagging or retardation of relative movement between the plunger l2 and tappet body II when forces acting axially upon the ends of the tappets are subjected to changes. The magnitude of this effect may be controlled by varying the clearance between the inner peripheral surface of the packing element l6 and the cylindrical portion of plunger l2 which the packing element sur rounds. This mechanical hysteresis effect of the packing element IE 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 similar to that disclosed in Fig. l is illustrated. In this construction the only modification is in the plunger I2 and relates to the manner in which 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 fitted upon the reduced end 31 of plunger 12' in order to retain the lower end of packing spring i 8 connected to'the plunger l2 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, providesa yieldable packing element l6 of ductile material adapted to be maintained in sealing contact with the wall of the bore of the tappet body If by the high pressures in the hydraulic compression chamber 3! for substantially sealing the plunger 12 with respect to the tappet body ll. Such high pressures also cause the packing element I6 to be forced into and maintained in sealing engagement with the washer l5 and the valve member H to effect a seal with the flange 26 of plunger l2. The coined or grooved surfaceof valve member l4 and the upper surface of the washer l5 are also 7 brought into contact so that the spiral groove in the lower face of valve member |4 affords means for allowing only a definite and predetermined leakage or escape of oil fromthe hydraulic compression chamber .3l. The construction of the remaining elernents and their arrangement is the same as that illustrated in Fig. 1.

Reference may now be had to Fig. 6 which illus- I trates a modified formof tappet construction.em-

bodying the principles of the present invention, this construction includinga cylindrical tappet body 4| provided with a bore 42, which affords the shoulder 43 for supporting a separatecylinder 44 adapted to be received within the upper end of the bore 42. I z

The tappet body is provided with an annular recess 45 and an admission port 46 and isotherwise of substantially the same construction as that disclosed in the embodiment shown in Figs. 1 and 5. The separate cylinder 44 is provided with a cylindrical bore 41 and a reduced and bored boss portion50 in which has been press fitted a suctiontube 5| and a valve retaining cage 52. A ball check valve 53 is disposed within the cage 52 for limited movement therein and is adapted to make a fine line contact with the upper end of the bore of suction tube 5|, so that the upper end of the bore Wall of tube 5| forms the valve seat. for the return valve 53. The upper end of 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 supplychamber 55 formed bythat part of the bore 42 which lies below the separate cylinder 44. The tappet plunger56 makes a loose Or-sIidingfit within the bore 41 of separate cylinder 44.; A cylindrical washer member 51 makes a similar fit within the bore 41 of separate cylinder 44 and is arranged within the latter bore immediately below the plunger 56. A packing washer 1 v 60 of the same character as the washer I6 previously described and a packing retainer washer 5| 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 64 of the. tappet.

During the operation of this tappet construction, oil Orotherliquid under pressure is adcompression chamber mitted through the annular recess 45 and port ll to the preliminary or reserve supply chamber 5!. The plunger spring I! causes'extension of plunger I until the latter contacts one valve operatins part and the closed endof the tappet body 4i contacts anothervalve operating part. Outward movement of the plunger 56 creates a partial vacuum condition within the hydraulic compression chamber 64 causing the valve 53 to lift from its seat and liquid medium to be drawn upwardly through the suction tube 5| into the hydraulic 64 of the tappet. when an' engine valve is lifted by the tappet, the increased pressure within the hydraulic compression chamber 64 is exerted upon the inner periphery of the yieldable packing element 60 and upon the lower surfaceof the latter, tending to cause the material of the packing to flow outwardly and provide a seal between the packing and the bore 41 of the separate cylinder 44. The increased pressure exerted by the liquid medium within the hydraulic compression chambercauses the adjacent surfaces of washer 51 and the yieldable packing element to 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. The surfaces are pressed together by a I force substantially equal to the entire load of the valve operating gear at the time of opening of the engine valve. The leak-down rate between the plunger and separate cylinder is controlled by the lowersurface of the plunger 56 and the upper surface of the washer 51, one of the surfaces either being grooved as indicated at 32 in the construction shown in Fig. 1 or one or more of these surfaces being left in a suiliciently roughened condition, not polished, to provide the proper leakdown rate between theplunger and the separate cylinder. In this construction the yieldable packing element 60 is substantially confined by the washer SLseparate cylinder 44, the packing retainer washer BI and the oil or other liquid medium within the hydraulic compression chamber 64. Thus the 'yieldable or ductile packing element 60 aflords substantially the same mechanical hysteresis efiect in producing a lagging or retardation of movement of the plunger with reference to the separate cylinder when axial forces directed against opposite ends of the tappet are varied as in the previously described constructions. The

ball valve 53 is gravity and inertia actuated as well as by differential fluid pressures to cause its return to and maintenance in seated position during lift of the tappet;

Referringto Fig. 'l, a tappetvery similar in construction to that shown in Fig. 6 is illustrated.

' Inthis construction the plunger 56', corresponding to the plunger 56 of the previously described embodiment is provided with a reduced end portioniladaptedto contact a valve stem or other j valve operating part for an exhaust or intake valve of an internal combustion engine. An abutmerit 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 suflicient distance to cause breakage of the latter or of the cylinder head of the engine. The remaining parts shown in Fig. -7 correspond with aaa'naas like parts shown in Fig. 6 and are given the same numerals.

In all of the liminary 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, or through clearance between the separate cylinder and the bore of the tappet body as in the case of the embodiment shown in Figs. 6 and 'l. The ductile packing elements are forced radially outwardly by flowing the material thereof ,in that direction in order to seal the plunger with reference to its cylinder. A mechanical hysteresis effect is afforded by all of theillustrated embodiments due to forcingthe ductile and yieldable packing to flow the material thereof outwardly against the wall of its confining cylinder, the packing otherwise being substantially confined by the plunger element or elements carried thereby and the oil in 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 the plunger so that operation of the engine valve will be had, although with some lift loss, in the event of failure of oil supply and after oil in the preliminary or reserve supplychamber has been exhausted. In the embodiment shown in Figs.

1 and 5, the lower end of the plunger if or the element 36 abuts the closed end 23 for limiting inward movement of 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 inwardly with reference to the separate cylinders 44 or .As many changes could be made in the above construction, and many apparently widely different 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:

1. 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 defining a hydraulic compression chamber, means for ad mitting 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, abut at one face thereof the plain surface of said flange to provide a check valve, the other plain surface of said valve disc being provided with a groove of small crosssection and extended length, a second plain surface disc positioned to abut the grooved surface of said valve disc to complete a small cross-section passage of relatively long .lengthfor limiting to a slight amount'leakage from said hydraulic compression chamber, and a yieldable element formed of a ductile material substantially confined by said illustrated embodiments, the pre- 2,927,958 portion slidably engageable with the cylinder walls, a continuous sealing ring positioned at the end of the plunger body adjacent the reservoir and movable with the plunger, said ring having a peripheral portion 01 ductile material engageable with the cylinder walls to resist the escape of fluid from the reservoir past the plunger, and

- a pressure reliei. member cooperating between the sealing ring and the plunger providing for a limited escape oi fluid past the sealing ring.

3. In a valve tappet, a cylinder having a fluid reservoir therein, a plunger having a body portion slidably engaging the cylinder walls, a seal com- I prising a member of ductile metal having a circular outer edge and positioned at the end of the plunger body adjacent the reservoir with the circular edge slidably engaging the cylinder walls throughout the circumference of said edge, said member being movable with the plunger and having an opening therethrough tor the passage of fluid, and means associated between said member and said plunger providing a restricted by-pass ior fluid escaping through the opening in said member.

4. In a valve tappet, a cylinder having a fluid reservoir therein, a plunger having a body slidably engageable with the cylinder walls, a seal positioned between the plunger body and reservoir and movable with the plunger, said seal comprispositioned members having circular outer edge portions, at least one of said members being formed of ductile material frictionally engaging ing a plurality of independently movable Juxta-

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