US2090795A - Hydraulic tappet - Google Patents

Description

. zpsw s c. E. JOHNSON HYDRAULIC TAPPET 2 Sheets-Sheet 1 Filed Oct. 5, 1936 Aug 1193? I c. E. JoHNsoN 2,0Q0f795 HYDRAULIC TAFPET Filed Oct. 5, 1936 2 Sheets-Sheet 2 Patented Aug. 24, 1937.

yUNlTED STATES PATENT OFFICE 12 Claims.

This invention relates to self adjusting valve tappets to be used in connection with the valves of internal combustion engines, and more particularly of the hydraulic type disclosed in my copending applications, such as Ser. No. 625,622 filed June 29, 1932, or Ser. No. 585,859, filed Jan. 11, 1932.

In internal combustion engines the valve tappets are members which are given a reciprocatory movement in one direction from rotating cams fixed to or integral with a cam shaft. The valves for opening and closing an intake or exhaust port in the engine have stems which bear. against the ends of the valve tappets, the valves being lifted when the cams move'the tappets in one direction. Springs associated one with each valve move the valves in the opposite direction to close the valves when free to do so. These springs have relatively strong force and are compressed when the valve tappets lift the valves off their seats.

In valve structures of this kind a clearance between the tappet and its associated valve stem is required and this clearance has almost mil- 7, versally heretofore been the subject of very careful mechanical adjustment. The clearance between the tappets and the valve stems must be provided in such a manner that when the engine is hot the valves will not be lifted above their seats due to expansion of the parts when heated; 30 therefore when the engine is cold there is a. gap or clearance of a. few thousandths of an inch between the tappets and the bearing ends of the valve stems which engage against the tappets. M Furthermore, the clearance should not be any greater than is necessary as excessive clearance causes hammering of the valves on their seats, undue noise in operation and a disruption of a proper timing of the valves in their movement. In the present invention a hydraulic actuated 4O adjustment of the tappet is provided which automatically takes up all clearance between the tappets and the valve stems and further automatithe parts are very closely fitted, this being very costly in manufacturing, if the oil which is under pressure of the oil pump of the engine becomes,

thin or attenuated, as is quite likely when the engine is fully heated, the seepage or passage of- 55 oil which controls the engagement of the tappet against the end of the valve stem between the tappet body and the guide sleeve in which it is mounted for reciprocation may be at such an amount when the engine is turning over at very low speed, that is, when the engine is idling, that the best operation of the automatic self adjusting tappet will not occur. 4

One of the objects of the present invention is to provide a very simple and practical means for controlling and preventing too rapid a passage or seepage of such oil whereby the tappet will function perfectly even though the oil is of a thin character and the engine at idling speed, and without the necessity of very close tolerances in manufacture of the parts. 15

Another object of the invention is to provide a tappet structure which is of a simple and very practical construction for large quantity production and with the greatest of economy in manufacture, so that cost may be kept at a minimum and to provide a tappet of readily manufactured 20 and very easily assembled parts. These and various other objects and purposes will be understood from the following description taken in connection with the accompanying drawings, in which ,7

Fig. 1 is a fragmentary section and elevation k showing a usual valve arrangement in an internal combustion engine with a tappet embodying the present invention installed therein.

Fig. 2 is an enlarged longitudinal vertical section through the tappet with the part in one position.

' Fig. 3 is a similar view showing the parts in another position and with the interior spaces of the tappet shown as filled with oil. 30

Figs. 4 and 5 are horizontal sections on the planes of lines 5-4 and 55 of Fig. 2 looking in a downward direction.

Fig. 6 is. a perspective view of an oil sealing member used with my invention.

Fig. '7 is a view similar to Fig. 2 showing a slightly modified form of structure attaining the same purposes and results.

Fig. 8 is a horizontal section on the plane of line 8-8 of Fig. '7.

Fig. 9 is alongitudinal vertical section similar to Figs. 2 and '7 of a further formof structure for attaining the same results in the same manner. V

Figs. 10 and 11 are horizontal sections respectively taken on the planesof lines lib-l0 and Il--l| of Fig. 9 looking downwardly. I

Fig. 12 is a section similar to Fig. 9 of an additional equivalent valve tappet structure and,

Figs. 13 and 14 are horizontal sections taken respectively on the planes of lines l3-i3 and Like reference characters refer to like parts in the diiferent figures of the drawings.

In Fig. 1 the wall of a cylinder is indicated at l, a port, which may be an exhaust or intake port at 2 having a valve seat 3 at one end against which a valve 4 engages. The valve has an elon gated stem 5 guided through a suitable sleevelike guide 6. A heavy coiled compression spring 1 seats at one end against a seat member 8 on the valve stem and at the other end engages against a part of the engine block around the stem guide 6, the spring acting to draw the valve 4 into tight engagement with the seat 3 when free to do so. This is a conventional valve structure in internal combustion engines, there being at least one intake and one exhaust port for each cylinder of the engine and a valve associated with each of said ports.

In my invention the tappet includes a cylindrical substantially hollow body 9 closed at its lower end which has a mounting for vertical reciproca tory movements in a. tappet guide sleeve l 0. The tappet body 9 between its ends has a shallow and relatively wide groove H made continuously around it. Oil is pumped by the oil pump of the engine into a conduit l2 which is made along the bank of tappet guide sleeves [0, the 011 being pumped thereinto through a lead-in pipe l3. It isevident that oil is pumped into the annular chamber at the groove ll between the tappet body and the guide sleeve 10 is filled with oil under pressure. A cam shaft H, which is continuously rotated when the engine is in operation, carries a plurality of cams I5, one under the lower end of each tappet,'so that when the cam l5 passes underneath the body 9 of the tappet the valve is lifted, compressing the spring I, and after the cam has passed from the tappet the spring I returns the valve to its lower closing position.

As shown in Figs. 2 and 3, the body 9 has cast integral therewith an inwardly extending annular ledge l6, against ,which a member or plug I1 is pressed at the upper side, the part I! having a press fit within the body of the tappet. A hori zontal passage I8 is drilled through the member I! alining withthe openings l9 made opposite each other in the walls of the body 9. In pracwithin the chamber 20 and is adapted to rest upon the annular lip 22, the diameter of the body of the valve member 23 being substantially equal to the exterior diameter of the annular lip 22. A flat plate 25 rests upon the member I! and covers the ,chamber 29. At its central portion the plate 26 has a number of small openings 26 and,

preferably at its center, it is pressed downwardly to make a projection 21 which serves as a stop against excessive upward movement or fluttering of the valve 23.

Immediately above the member I1 and the plate 25 the body 9 is machined out to a slightly larger diameter, this being so that the member I! and the plate 25 may be readily installed without forcing the same the entire length Iron; the uppe has a small central opening 26a of larger diam- The chamber 44 -is surrounded by a cylindrical end of the body 9. Within the upper portion of the body a piston 28 is mounted, having a portion 29 of reduced-diameter at its lower part. The piston is of a hollow construction integrally closed at its lower end and having its upper end closed 5 by a cap 30 preferably welded in place. The cap is of a conical form as shown in Figs. 2 and 3,- though it need not necessarily be of such form, and has a head 3| at its upper end which comes directly underneath the lower end of the valve 0. stem 5.

In the form of structure shown in Figs. 2 and 3 the piston, at the shoulder between its larger portion 28 and smaller portion 29, is machined so as to have a downwardly and inwardly in- 15 clined face as shown at 32. A ring 33, parted at one side as shown in Fig. 6, bears at its outer curved surface against the inner walls of the body 9 and at its upper end has an inclined structure so as to fit snugly against the inclined shoulder 32. The inner diameter of the ring 33 is larger than the exterior diameter of the smaller part 29 of the piston thereby providing a continuous annular space or chamber 34 between the inner side of the ring 33 and the outside of the piston part 29. A coiled compression spring 35 bears at its lower inner end upon the plate 25 and at its upper end against the lower end of the ring 33 thereby pushing the ring upwardly until its inclined upper edge engages the inclined shoulder 32, whereupon the continuing force of the spring 35 tends to outer curved surface snugly engages the inner walls of the tappet body 9, in addition to the pressure of oil in chamber 34 which also presses the 35 ring outwardly.

A continuous groove 36 is made around the ring 33 adjacent its upper end, and horizontal passages 31 are made from the groove 36 inwardly to the inner curved side of the ring 33, thereby communicating with the annular space or chamber 34. -'I'he body 9 has openings 38 positioned so that when the piston is in its lowermost position, shown in Fig. 2, the groove 36 comes into conjunction therewith. This eliminates any air that may gather in the tappet. At the upperv end of the body 9 an annular groove is made around the inner walls of the body and a parted spring wire snap ring 39 located in said groove preventing the piston from being withdrawn from the body 9 until the ring 39 has been removed.

In Fig. 7 the shoulder 32a shown is a horizontal shoulder instead of inclined, and the upper end of the ring 33a is made to correspond. The closure, having the head 31a at the upper end. of the piston, is of a slightly diflerent though equivalent form. The chamber 20 is the same but the valve 40 in said chamber is of a different construction being a circular plate with a plurality of small openings 4| in the peripheral portions thereof beyond the edges of the passage Zia leading from the chamber to the passage I8 in the member H. The plate 25, instead of having a plurality of small openings 26 therein at its central portion,

eter.

In Fig. 9 the member 42, which occupies the same position and is the equivalent of the member IT, has an L-shaped passage 43 at its outer end in conjunction with an opening l9a in one 7" side only of the body 9. The upper end of the L- shaped passage 43 communicates with a chamber 44 in which'there' is a ball valve 45 which, under gravity, closes the upper end of the passage 43.

wall 46 which is made by cutting an annular recess ,in the upper sideof said member. The

. chamber 44 isclosed at its upper end by a pressedthe cap Si.

in plug 41 which has small outlet openings therethrough.

The piston 48 is of a modified structure being made of one part only and having a central vertical stem 49 which comes directly underneath the lower end of the valve stem 5. A spring ring 50 is seated in a groove made at the inner side of the piston 48 and has an end 5| bent to pass through an opening made in the wall of the piston 48, and enters an annular groove 52 in the inner wall and near the upper end of the body 9. A split ring 53 of triangular cross section has an inner downwardly and inwardly inclined annular surface 54 shaped to conform to a complementary surface at the lower part of the piston 48. A coiled compression spring 55 bears at its upper end against the ring 53 and enters the annular recess made in the member 42 around the cylindrical wall 46. The ring 53 has a continuous groove 56 around it, to serve the same purpose as the groove 36 in the ring 33, and a plurality of passages 51 lead from the lower side of ring 53 upwardly and outwardly to the groove 56, for the escape of any air that may collect.

In the form of structure shown in Fig. 12 the chamber 44, in which the valve 45 is located centrally of the member 42, is the same as in Fig. 9. The member 42 is similar to member 42 shown in Fig. 9, and 42 is covered by circular plate 58 which has a number of small openings 58a in its central portion over chamber 44. The ring 53 is identicalin structure with the r'ng 53 shown in Fig. 9 and a coiled compression spring 55a is located between the lower side of the ring 53 and the plate 58.

The piston 59 is similar to the piston 48 at the structure of its lower part. It has however a projection 60 at its lower end below the surface against which the inclined inner side 54 of ring 53 bears, around which the,upper part of the spring 55a is located. The open upper end of the piston 59 is closed by an inverted cup-like cap 6| which extends into and is permanently connected with the piston 59. The lower end of the valve stem 5 bears upon the upper side of A split spring ring 62 is seated in a groove around the outer curved side of the body 9 and at one end is bent inwardly at 63, passing through the wall of the body 9 and entering a groove 84 made between the upper end of piston 59 and the. annular flange shown on the cap 6|.

In the operation, as soon as the engine starts, oil is pumped through the pipe l3 into and around the body 9 and thence into the passage l8 filling the same and lifting the valve 23 in the construction shown in Figs. 2 and 3, or the valve 40 in the construction shown in Fig. 7 or valve 45 in Figs. 9 and 12, thence passing upwardly to engage against and lift the piston of whichever form is used until engagement of the upper end of the piston is made against the lower part of the valve stem 5.

head of the pieton against which the lower end of the valve stem engages is takenup in a very All clearance between the lower end of the valve stem and the upper end or then between the upper enlarged end portion of the piston 28 in Figs. 2, 3, and '7, 48 in Fig. 9 or 59 in Fig. 12 so that the expansion is compensated for so that the valve 4 is not held above its seat.

When the engine is operating at low speeds or is idling and the oil has become thinned or attenuated due to heating, without the ring 33, 330, or 53 the seepage of oil past the upper enlarged part of the piston, when the valve is lifted on upward movement of the valve tappet, may become too great,-so that at the lowermost position of the valve tappet the lower end of the valve stem separates from the upper end of the pistonand causes the tappet to become inoperative or operate incorrectly. The parted ring used checks such seepage sufliciently that engagement of the lower end of the valve stem 5 with the head of the piston with which it is associated remains practically constant, and there does not occur hammering of the valve 4 on its seat and clicking or other undesirable noises when the succeeding upward movement of the tappet strikes the piston therein against the lower end of the valve stem.

The rings used indicated at 33, 33a, and, 53 are of a size so as to be received readily within the tappet body 9. With structure shown in Figs. 2 and 3 there is a double force acting to expand the ring. One is the pressure of theoil in the annular space 34 against the inner side of the ring and the other the force of the spring 35 pushing the ring upwardly so that a wedging action is produced tending to expand the ring when its upper end engages the inclined shoulder- 32. In Fig. 7 a single hydraulic force tends to expand the ring at the proper cycle when the valve 5 is lifted. This is the pressure of oil in the annular space between the lower part 29 of the piston and the inner curved side of the ring. In the structures shown in Figs. 9 and 12 there is not the same kind of oil pressure force tending to expand the ring, but there is a wedging action due to the pressure of the spring 55 or 55a actin against the under side of the ringand bringng its inclined side 54 against the complementarily inclined surface on the piston 48 or 59.

It is quite common for air to become mixed with the oil and this will separate out and move to the highest level possible, that is, into the annular chamber 34. The air is readily cpmpressible and when the valve is raised the force of the valve spring I pushes the piston down to the position shown in Fig. 2 wherein an outlet for the air from the upper part of the chamber 34 is made through the passages 3l and the conjunction of the groove 36 with the outlet openings 38. In Figs. 9 and 12, the air collected at the upper part of the space above the member 42 or plate 58 escapes through the passages 5'! when the groove 56 in the ring is moved downwardly to the outlet openings 38a. 1

It will be evident that the machining operations of building the tappet in accordance with the disclosures made are of a kind conducive to high quantity production with low costs of manufacture. The body 9 may be finished by suitable drilling or reaming operations to receive the member H or 42. Above this portion of the body the reaming of the same to size may be quickly accomplished. The members IT and 42, also the pistons used may be machined rapidly ona lathe, screw machine or other suitable mechanism. The holes to be drilled may be rapidly drilled and the production of the split rings used is also a high quantity production process. The valves are either simple stampings or balls, the plates 25 and 58 are likewise simple stampings. With this structure of tappet with machines rigged for the purpose the parts may be produced very economically and at high-speed. The assembly 5 is also of the simplest character. Alter pressing the member I! or 42 into place the other parts are put in in succession by mere insertion.

The constructions described are therefore not only particularly .efilcient to take care of the 10 problem of automatically adjusting the tappets to all conditions of engine operation, but the tappet structure itself may be cheaply manufactured and assembled. The claims appended hereto define the invention which is to be considered is comprehensive of all forms of structure coming within their-scope.

I claim:

l. A valve tappet of the class described comprising, a hollow cylindrical tappet body closed 20 at its lower end, a plug having a press fit within said body member between the ends thereof, said plug and body member having lateral inlet passages for oil and said plug having a vertical outlet for said passage at its upper side and substan- 25 tially' at its center, a piston reciprocably mounted within the body member above said plug, a valve at the inner end of said piston within the body member above the plug, said piston having a -lower portion of reduced diameter with a shoulder 3 between the same and the upper portion 0! the piston, and a split ring having its upper edge bearing against said shoulder around the lower reduced portion of the piston and'having its outer curved side bearing against the inner walls of 5' the hollow body member.

2. A construction containing the elements in combination defined in claim 1, said split ring having an inner diameter greater than the exterior diameter of the lower reduced portion of the 40 piston whereby there is provided a continuous annular space between the lower part of the piston and said ring.

3. A construction containing the elements in combination defined in claim 1, said shoulder between the larger upper and lower smaller parts of the piston having a downward and inward inclination to a horizontal plane, and the upper edge of said ring having a corresponding inclination, and a coiled compression spring between the lower end of the ring and said plug.

4. A construction containing the elements in' combination defined in claim 1, the interior diameter of said ring being greater than the exterior diameter 01' the lower smaller end of the piston whereby a continuous annular space is provided between the ring and the adjacent sides oi the piston, said ring having a groove around its other side andpassages extending from said groove through the ring, and said body having a lateral e through the wall thereof in a position whereby the groove in the ring joins therewith in a lower position of said piston and ring for the purpose of dispelling air.

5. A valve tappet of the class described comes prising, a hollow body member of elongated cylindrical iorm having a closed lower end, a piston mounted for reciprocatory movements in the upper portion of said tappet body, valve carrying means within the tappet body below the piston having an oil inlet passage and a valve associated therewith for controlling the passage of oil into the tappet body below the piston and stopping its passage in a reverse direction, an elastic ring surrounding the piston and bearing 75 at its outer curved side against the inner walls of the tappet body, and spring means acting on 6. A construction containing the elements in combination defined in claim 5, combined with means providing a chamber, for the collection of air in the oil between the piston and ring, and means providing for the escape of said air when the piston is moved downwardly in the tappet body to a predetermined position.

7. A valve tappet of the class described comprising, a tappet body member of elongated cylindrical form having an axial opening closed at its lower end, a plug secured in said body member between the ends thereof, said plug and body member having an inlet passage for. oil and said body member having a valve chamber to which said passage leads, a valve within said valve chamber normally closing the passage, 9. piston inthe body located above the plug, said piston having a lower end portion of a diameter less than the upper portion with an annular shoulder between the two parts of the piston, a packing ring around the lower part of the piston having its upper end bearing against said shoulder, the inner diameter of the ring being greater than the exterior diameter of the lower part 01' the piston whereby pressure of oil between the piston and the inner side of the ring tends to outwardly expand the ring.

8. A construction containing the elements in combination defined in claim 7, combined with a plate covering the valve chamber and having passages therethrough for oil, and a coiled compression spring having its lower end bearing against the upper side of said plate and its upper end bearing against the lower' end of said ring.

9. A valvetappet comprising an elongated cylindricakhollow tappet body closed at its lower end, a plug having a press fit within the tappet body between its ends, said plug having a centrally disposed valve chamber and an oil inlet passage leading thereto at the lower end of the valve chamber, the opposite end of said passage having conjunction with an an entrance opening through a side of the tappet body, a valve located within said valve chamber for closing said passage, a plate covering the valve chamber, said plate having an opening for oil e, a piston mounted for longitudinal movements within the tappet body, saidpiston having a lower .end portion of reduced diameter, a split ring within the tappet body around the lower part of the piston and bearing at its upper end against the lower end of the larger upper portion of the piston, and a compression spring between the lower end of said ring and said plate.

10. A construction containing the elements in combination defined in claim 9, said ring having an inner diameter greater than the exterior diameter of the lower smaller part or the piston, thereby providing an annular chamber into which oil may'enter andat theupper part of which air when the piston and ring occupy a predetermined position within the tappet body.

12. A valve tappet of the class described comprising; a tappet' body of elongated cylindrical form, said body being hollow and closed at its lower end, a plug having a press fit into and located within the body between its ends, saidplug in the upper central portion thereof having a valve chamber and a passage leading from said valve chamber laterally to a side of the body, and

; said body having an opening in conjunction with said passage, 2. plate covering the valve chamber, a valve within the valve chamber below said plate, a piston mounted for reciprocating movements within the upper part of the body, said. piston having a head at its upper end against which the lower end of a valve stem is adapted to engaget said piston comprising an upper portion having an exterior diameter slightly less than the interior diameterof the upper part of the valve body and having a lower portion of a reduced diameter with an annular shoulder between the

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