US2751896A - Mechanical valve tappet - Google Patents

Description

United The present invention is directed to mechanical valve 'tappe'ts and is more particularly concerned with an automatieally adjustable mechanical valve tappet which is maintained in proper relation as to its contact with the lower end of a valve stem of an internal combustion engine, or of a push rod for overhead valves, there being an elimination of t-appet noises, such as clickings and the like, and a perfect maintenance of the contact and with no space between the contact points of the tappet and valve stem or push rod, which is known as the flash, as applied to clearance between valvesterns or push rods and the contact points of the valves therefor, and which lash or clearance is provided by means of a shim of desired thickness between the valve tappet anda valve stem orpush rod in the adjustment of usual mechanical valve tappets.

With my invention, a novel and very elf ectivetappet structure is provided, automatically self-adjustable and which is usable both with the cams of cam shafts designed for the usual mechanical tappet operation, or for the earns of cam shafts designed for hydraulic tappets which are automatically adjustable, between which and valve stems or push rods no clearance or lash is present.

It is the primary object and purpose of my invention toprovide a novel, exceptionally practical and elfective v'alve tappet, usable under all conditions of internal corn bus't ion engine design, either with engines designed for mechanical tapp'ets or hydraulic tappets, and which may be installed in new engines or used for replacement of ta'ppets in engines in service. An understanding of the invention may be had from the following desoription, taken in connection with the accompanying drawings, in whioh:

Fig. l is a vertical sectionsubstantially on the plane of line 11 of Fig. 3, through a tappet made in accordance with my invention, and shown in association with an operating cam therefor and an engine valve which is openedor closed by the movements of the tappet, the parts of the tappet being shown in one position.

Fig. 2 is a fragmentary vertical section of the lower part of the tappet, with the parts thereof in another posit-ion which they take during engine operation,

Fig. 3 is a horizontal section and plan view, the sec- 'tion being substantially on the plane of line 3--3 of Fig. 1, and

Fig. 4 a fragmentary section through the upper portion of the tappet on substantially the same plane as Fig. 1, the tappets in Figs. 1 and 4 respectively slightly difiering in structure for use, one in conjunction with intake valves of internal combustion engines, and the other with the exhaust valves thereof. y

Like reference characters refer to like parts in the diher'ent figures of the drawing.

The tappet includes in its structure a tappet bodywhich has a closed horizontal lower end 1 andv cylindrical walls 2 i eg'ra'l therewith, the body being open atits upper end, and having an on drain ge ape-hing through the wan 2 near the lower end 1. With my invention the lower States. Paten (3 r 2,751,896 Ice Patented June 26, 1956 side of the lower closed end 1 which bears against the actuating cam for the tappet is in a plane inclined slightly to the horizontal. That is, the lower side 1a, at one side of the tappet body is offset from horizontal, indi cated in dotted lines, a distance of a few thousandths of an inch which in practice may be between the limits of .005 to .015 inch .per lineal inch of the diameter of the tappet body. This is to prevent axial turning of the tappet body which must be avoided in connection with the hereafter described movable weight, and to give a positive uniform stress between the cam and such body.

At the open upper end portion of the walls 2 of the body the interior opening is increased in diameter a small amount, providing an annular horizontal shoulder below the upper end of the walls 2 against which a ring 3 of metal is placed. An interiorly threaded sleeve 4 is formed at its upper endwith an integral outwardly extending annular flange 5, the exterior diameter of which is slightly less than the interior diameter of the enlarged upper portion of the opening into the body. Flange 5 is located over the ring 3 and the sleeve extends downwardly through the central opening of the ring.

A specially constructed screw is threaded through the sleeve 4. It includes a head'6 at its upper end, from which an exteriorly threaded section 7 extends downwardly through the sleeve 4, and having its uppermost threads below the uppermost threads of the sleeve to avoid vanish binding or wedging, Around the screw shank an annular groove '8 is cut at the lower-rend of the threaded section 7, below which is a shorter threaded section 9, having a limited number of screw threads thereon. The shank of die screw is extended below the threaded section 9 in a plain cylindrical terminal section 10 from whieh a pin 1i elitends radially to one side. The threads are at a sufficien'tly flat pitch that the screw will not turn in the sleeve from downward pressure on head 6.

A weight 12 is mounted on the section ill for tree turning thereabout. The pin 11: extends through a slot 13 provided in the weight 1-2 whioh is open at its lower end at the law er end of the weight, and is of an arc fo'fifi curving upwardly and laterally as shown.

A not 14 is screwed onto the lower short threaded section 9 of the screw, having an annularrece ssat its upper endwhich receives a split spring ring 15 in the groove 8. Such ring "serves as a stop against which the nut comes when it is applied to the threaded section 9 and screwed thereon. The distance between the upper side of the weight 12 and the lower side of the nut 9 is such that when the weight is in its uppermost position (Fig. 2) the pin 11 is at the open lower end of the slot. The weight normally, by gravity, will drop to lower po- 'sition as in Fig. 1 with the pin at the upper closed end of the slot 13. v

The nut at opposite sides as recessed by reeesses having sides at rightan'gles to each other, preferably, as shown at 16. Suoh nut around its upper end portion is formed with an integral outwardly -extending flange 17, beveled at its upper outer corners. The flange terminating at one of the recesses 16 which have been described, is cut away for a distance back from each of the sides of the other recess 16, as shown at 18 in Fig, 3.

A torsion spring 19h located around the sleeve 4 which at its upper portion is of a greater diameter than at lower portion below a flange 20, similar to the flange 17, and having parts thereof removed. Flange 20 is'he'veled at its lower outer corners. The diameter of the nut 14 between the flange 17 and a lower outwardly extending flange 14a thereon is likewise greater than of the lower portion of the sleeve 4. Therefore, the intermediate coils of the spring 19 between the nut 14 and the flange 20 on the sleeve 4 is a short distaricei frorrrthe Sleeve, whilethe lower end coin or the springls' Bind u on or are cinched against such'nut 14 and'the'upper coils cinched against the 'upper portion of sleeve 4. The end of the lowercoil in Fig. 3. The opposite end of the spring at its upper coil has a terminal portion 19b extending through an opening in. the flange of the interiorly threaded sleeve 4. A'split spring ring retainer 21 of spring wire is received in an annular groove at the upper end portion of the walls 2 of the tappet body and at the inner side thereof, against which the flange 5 of the sleeve 4, at its upper side, engages. Flanges 17 and prevent the lower and upper end coils from movement in a vertical direction.

When the tappets are to be used as replacement tappet in engines originally equipped with the usual mechanical tappets, a dished washer 22, as shown in Fig. 1, or two of them reversed with respect to each other as shown in Fig. 4, are placed between the ring 3 and the flange 5, of the sleeve 4. Such washer or washers in strength are less than the valve spring with which associated, so that the dished washer or washers completely collapse at a load less than the pre-load of the valve spring. The washers in the trade are commonly known as Bellville washers. The gap between a ring 3 and the flange 5 will vary in diflerent engines, such gap being the clearance or so-called lash" selected by the designing engineer for the particular engine which he designs. The Bellville washers are used only in tappets which are to replace or take the place of regular mechanical tappets. When the'tappet of my invention replaces automatic tappets of either hydraulic or other forms, and in which the cam are of different design, the washers 22 are not used as they are not needed, no lash or clearance being provided in engines having such type of tappets and actuating cams therefor.

The double washers 22 as shown in Fig. 4 are used with tappets which are associated with exhaust valves, and the single washer 22 used with tappets to lift inlet valves of internal combustion engines.

The valve body 2 and the parts associated therewith are raised and lowered by the rotation of a cam 23 in the usual manner. The stem 24 of an engine valve is engaged at its lower end by the upper side of the head 6 of the described screw, the usual heavy spring 26 being associated with the valve and which when free to do so will close the valve against its seat to make a tight closing engagement therewith.

The flanges 17 and 20 cut away as indicated at 18 on the flange 17, and similarly on the flange 20, facilitate the assembly of the spring 19 with the sleeve 4 and nut 14, as the ends of the end coils of the springs may be readily introduced to pass under flange 17 and over flange 20 and be turned until a sufiicient number of the end coils are around such nut and the upper portion of the sleeve 4 and connect therewith with a tight binding engagement.

The tension of the spring 19 is regulated through a relative turning movement of the nut 14 as in Fig. 3 in a counterclockwise direction so as to move it with relation to the relatively fixed spring 19 and its end 19a to wind the spring torsionally, the recesses at 16 and the shoulders behind which the end 19a of the spring engage acting substantially as a ratchet. When the spring is wound to a desired tension, the tendency of the nut to turn in a clockwise direction will bring a shoulder at a recess 16 against the end 19a of the spring. The spring is assembled under a pre-load'of suflicient amount to cause an upward push of the screw with a force of from 3 to 12 pounds in practice.

In the operation, with the tappet in its lowermost po- 'sition as in Fig. 1, and with the circular or base circle portion of cam 23 hearing against the side 1a of the body, the weight 12 is at its lower position hanging upon and being supported by the pin 11. On rotation of the cam to lift the tappet such weight remains in lower position until the uppermost position of the tappet is reached. At the peak of its rise against the cam the tappet body stops and the weight 12, due to the momentum of its upward movement, moves upwardly on the section 10 of the screw and strikes against the lower side of the nut 14, at which time the weight is moving solely in a vertical direction, as the pin 11 (Fig. 2) is in the substantially vertical lower end portion of the slot 13. The weight remains in such position as the tappet body and other parts associated therewith move downwardly with accelerated speed, until the tappet has reached its lowermost position and is stopped against further downward movement, resting upon the circular or base circle portion of the cam. The weight thereupon moves downwardly and is spun about the vertical axis of the screw, striking the pin 11 at the upper closed end of the slot 13 with an impact force in a horizontal direction, which turns the screw at its threaded section 7 in the sleeve 4 in a downward direction, making a clearance between the valve stem 24 and the head 6 of the screw. This insures that the valve 25 will reach and properly engage its seat so as to close the port of the engine at which the valve is located.

While the lower end of thebody 1 is upon the circular or base circle portion of the cam 23, such clearance is automatically taken up by the torsion spring 19 which will turn the nut 4 and the screw in the opposite direction until the head 6 comes against the lower end of the valve stem 24. The difference between the amount that the screw is thus wound back by the spring 19, and that it was operated in the opposite direction by the impact of the weight 12 on the pin 11 is the amount of valve growth on the preceding cycle of the engine.

It is of course apparent that when the clearance between the valve stem 24 and the head 6 of the screw occurs through the impact of the weight 12 against the pin 11, the washer or washers 22 in those installations where they are used will tend to resume their normal position, and the return of the screw head 6 against the head of the valve stem 24 will be with the ring 3 and flange 5 separated as shown in Fig. 1, thereby providing the constant clearance required for running on the cams of a cam shaft designed to accommodate standard lash type lifters. Such washer or washers are completely collapsed when, upon the upward movement or'lift of the tappet, the force of the valve spring 26 comes into action holding the valve closed until such collapse has occurred after which the valve is lifted. To insure the cinching eflect of the end coils of the spring 19 upon the nut 14 and upon the upper portion of the sleeve 4 the outer sides of the nut, where such spring is located, and of the sleeve, are preferably disposed at a slight angle to the vertical diverging downwardly and outwardly on the nut and upwardly and outwardly on the sleeve,-

respectively.

The slot 13 in the weight 12 has a constant radius, and such slot is located in such a manner as to allow the upper closed end of the slot to strike the pin a blow in a horizontal direction to wind the torsion spring 19. The lower end of the slot is located so that in association with the pin 11 the weight is impelled to move vertically before the upper surface of the weight 12 and the lower surface of the nut 14 strike one another. The slot 13 is at one side only of the weight and must be angularly placedwith respect to the pin 11 to allow linecontact between such pin and the upper closed end of the slot." A

close or flush contact between the pin and the weight should be avoided in order to eliminate a cushion action under such circumstances, when both the weight and the pin are covered with lubricating oil.

With the tappet structure described, changes in longi-, tudinal dimensions of the valve stem or a push rod in the case of overhead valves caused by changing temperatures are immediately compensated for, there being a maintenance of contact of the head of the screw with the lower end of the valve stem or of a push rod there against at all times when the tappet is doing its work of lifting the valve. The only clearance which takes place between the screw head and the valve stem or push rod is for substantially an instant of time as the tappet reaches its lower-most position to insure positive and complete setting of the valve against its seat, with substantially instantaneous closing of such clearance through the action of the spring 19. Such clearance and its closure occurs at each cycle of engine operation and insures that under all temperature and other conditions of the engine the tappet, when lifting the valve and for a short period of time before the lifting occurs, will be in contact with the valve stem or push rod, and there will be no noises or impingement of the head of the screw against valve stem or push rod during the time that the longitudinal expansion of valve stem or push rod occurs after starting a cold engine and until it is fully warmed up; or at other times when tappets are faultily adjusted. There is also assurance that valves will always be closed when they should be. is far simpler in structure and operation than a hydraulic tappet, less liable to get out of order and need repair or replacement, more economical to produce and serves fully every purpose, function and effect, insofar as elimination of noise and assuring proper valve operation are concerned, as do hydraulic tappets. Also hydraulic tappets are prone to leak down oil therein when stopped at any portion of the associated cam rise, which is eliminated with the present tappet, which does not have oil leakage.

The invention is defined in the appended claims and is to be considered comprehensive of all forms of structure coming within their scope.

I claim:

1. An insert mechanism adapted to be entered at the upper end of and into a vertically positioned tappet hollow body having a closed lower end comprising, a vertically positioned screw having a head at its upper end, an upper longer threaded section and a shorter lower threaded section spaced from the upper threated section, said screw having a groove therearound between said threated sections and said screw, below the lower threaded section having a downwardly extending cylindrical plain section, a pin extending radially from said last mentioned plain section, a ring member in said groove of the screw, a nut threaded on the lower threaded section adapted to The tappet is noiseless,

come against said ring at its upper side, a second longer nut threaded on the upper threaded section and spaced at its lower end from the first mentioned nut, said second nut having an outwardly extending annular portion, abutment means supported by said hollow body engageable by said annular portion to limit the movement of said second nut inwardly of the body, a coiled spring attached at its upper end to the upper nut and at its lower end to the lower nut, and a weight through which the lower pain section of the screw freely passes, said weight having a curved slot therein, from its lower edge extending upwardly and laterally, said slot being closed at its upper end, into which slot said radially positioned pin extends.

2. A structure as defined in claim 1, wherein said annular portion comprises an annular flange at the upper end portion or" said upper nut, having an exterior diameter adapted to closely approach the interior cylindrical sur face of a tappet body into which said mechanism is inserted, and said abutment means comprises an annular ring having an exterior diameter substantially the same as the exterior diameter of said flange located around said upper screw below said flange, and a dished ring washer between said flange and ring adapted to yield and flatten upon pressure thereagainst, said ring being adapted to have support upon a tappet body below the upper end of such body.

3. A structure having the elements defined in claim 1, said coiled spring at its upper portion having a gripping connection with the upper nut and at its lower end portion having a gripping connection with the lower nut, the lower end portion of said upper nut, below where the upper end of the spring has gripping connection therewith, being of reduced diameter.

References Cited in the file of this patent UNITED STATES PATENTS 1,798,508 Tucker Mar. 31, 1931 2,050,766 Russell Aug. 11, 1936 2,066,976 Holmes Jan. 5, 1937 2,406,817 Engemann Sept. 3, 1946 2,433,089 Burkhardt Dec. 23, 1947 2,468,332 Johnson Apr. 26, 1949 2,630,792 Engemann Mar. 10, 1953 2,633,112 Engemann Mar. 31, 1953

Images