US 1696866 A
Description (OCR text may contain errors)
Dec. 25, 1928.
w. A. SEAMAN PUSH ROD OPERATINGMECHANISM 2 Sheet-Sheet 1 Filed Sept. 23, 1926 M/fdfl? A 1560/7705 gwve'ntox Gwynne-11 Dec. 25, 1928.
W. A. SEAMAN PUSH ROD OPERATING MECHANISM- 2 SheetS-Sheet 2 Filed Sept. 23, 1926 i A, deaman gnm'ntoz Wad/6% ing the rapid reciprocation of the tappet.
Patented Dec. 25; 1928.
WILLIAM: A. SEAMAN, OF SAGINAW, MICHIGAN.
Application filed September 28, 1926. Serial No. 137,366.
is manually adjustable, and is so adjusted as to leave a slight space or clearance between the tappetand the adjacent end of the valve f stem or push rod operated thereby; This space may be reduced-through accurate adj ustment of the parts so as to be substantially infinitesimal in measurement, but some space must be left to accommodate the expansion of parts due to the variation of temperature in operation of the engine. The space necessarily existing between the tappet and the valve stem or push rod gives rise to objectionable ta-pping or hammering noises, due to sudden forcible contact of metallic parts dur- Further, the tappet, under the rapid li ting impulses of the operating cam, is driven against the valve stem or push rod with such force and so often as to cause objectionable wearing of parts and undesirable vibration and stress throughout the valve mechanism, as well as causing, through wear, the clearance space to increase materially, thereby increasing the noise and causing other inefficiences to arise.
The present invention has for its primary object the provision of a tappet whichv in operation, will constantly or continuously contact with the end of the valve stem or push rod for thereby closing the clearance space which ordinarily must be left.
A further object is to provide a t-appet of e the above character which is extensible and compressible for automatically lengthening and shortening to accommodate the variation in the length of the various parts of the valve mechanism caused by expansion and contraction from temperature changes.
Another object is to provide a tappet embodying a pair of telescopically and slidably associated members having an incompressible liquid cushion therebetween, means to supply the liquid of the cushion under pressure between said tappet members whereby the tappet is lengthened for keeping the clearance the liquid pressure of the cushion during the retreatlng movement of the cam whereby the tappet is allowed to shorten for permit-" ting complete return movement of the push rod and complete closing of the valve associated therewith.
, A still further object is to relieve the liquid pressure of the cushion by esca e of the liquid from between thetappet mem ers to a point between the contacting surfaces of the tappet and the cam, whereby when oil is employed as the 11 uid of the cushion, a film of oil will be had etween the surfaces for reducing wear. vibration and noise.
Still another object is to sup ly the li uid or oil of the cushion so that e ective lu rication is had between the tappet and its guide or slide bearing for further reducing wear and promoting the ease of movement of the tappet. A further object is to provide a self-adjustmg and shock absorbing ltappet which employs a liquid cushion and which is entirely devoid of frail and objectionable metallic springs and movable check valves.
Another object is to provide a tappet of the Figure 2 is a horizontal section taken upon line 2-2 of Figure 1;
Figure 3 is a section taken on the line 3-3 of Figure 1;
Figure 4 is a horizontal section taken on the line 4-4 of Figure 1;
Figure5 is a vertical section taken substantially upon line 5 -5 of Figure 1; and
Fi ure 6 is a fragmentary vertical sectiona view illustrating a modification of a rtlon of the embodiment of the invention illustrated in Figures 1 to 5 inclusive.
Referring more in .detail to the drawings, 5 indicates-a conventional form of guide or slide bearing which is usually formed integral with the cylinder block of an internal combustion engine and which is provided with a vertical cylindrical opening in which the tappet of the present invention is slidably fitted for vertical reciprocation. As is usual in constructions of this kind a rotatable cam shaft 6 is horizontally disposed below and slightly spaced from the guide or slide bearing 5 and has a cam 7 fixed thereon in position to engage the adjacent lower end of the tappet mounted in the slide bearing 5 as shown clearly in Figures 1 and 5. The adjacent lower end of the push rod or valve stem adapted to be engaged by the upper end of the tappet for being lifted to effect opening of the associated valve of the engine when the tappet is raised by the cam 7 is indicated at 8.
The present tappet includes a tappet body 9 which is centrally bored so that the upper end of the body is open and the bore is of cylindrical form, and so that the lower end of the tappet body is provided with a bottom wall having an integral shoe or plate 10 adapted to ride on the edge or surface of the cam 7, the tappet body 9 being provided with a cylindrical outer bearing surface adapted to snugly engage the bearing surface of the guide or slide bearing 5. The tappet further includes a tubular or cylindrical member or plunger 11 which is slidably fitted within the tappet body 9 and adapted to project slightly above the upper end of the latter, the plunger or tubular member 11 including a cylindrical body which is centrally bored so as to be open at its upper end and closed at its lower end.
A valve lifting member is engaged in the tubular member or plunger 11, and as shown in Figures 1 to 5 inclusive, this valve lifting member may consist of a bolt 12 having its stem adjustably threaded in the upper end of the plunger 11 so that its head is disposed to engage the lower end of the push rod or valve stem 8. As is well known in'the art, the adjustment of the bolt 12 is maintained by means of a 'amb nut 13 threaded upon the stem of the bolt 13 and engaged a ainst the upper end of the tappet, the nut 13 being engaged against the upper end of the tappet member or plunger 11 in the present instance.
The guide or slide bearing 5 is provided near its lower end with a transverse opening that communicates with the bearing op-.
ening of the guide 5 and has a nipple 14 threaded therein, which nipple is coupled as indicated at 15 with the adjacent end of an oil pressure line 15 that may extend from clearly shown in Figure 5, the plunger 11 is provided with a reduced lower end portion so as to leave an annular space as at 18 between such reduced end portion of the plunger 11 and the inner surface of the'tappet body 9. Extending transversely through the wall of the tappet body 9 at suitable uniformly spaced points are a plurality of openings 19 which communicate at their outer ends with the annular groove 17 and at their inner ends with the annular space 18 between the reduced end of the plunger 11 and the tappet body 9. The openings 19 provide constant communication between the groove 17 and the space 18 because the reduced end portion of plunger 11 is of suificient length to extend above the openings 19 even when the tappet is completely compressed-or collapsed with the plunger 11 eompletedly within the tappet body 9. Disposed within and seated upon the bottom or lower end wall of the tappet body 9 is a resilient block or rubber cushion 20 adapted to be engaged by the lower end of the plunger 11 when the tappet shortens for absorbing shock.
Extending through the cushion 20 and the lower end of the tappet body 9 is an oil passage or opening 21 arranged to lead oil from the lower end of the tappet body 9 onto the bearing surface or edge of cam 7. p
In operation, the engine is started in the usual way so as to cause rotation ofcam shaft 7 and the cam 7 carried thereby, at which time oil is supplied under pressure through the line 16 into groove 17 and through openings 19 into the annular space 18, the oil ultimately finding its way from the space 18 to a point between the cushion 20 and the lower end of plunger 11. Prior to starting the engine the screw 12 may be adjusted so as to leave a slight clearance space between the head of the same and the lower end of the rod or stem 8 in the usual way when the plunger 12 is substantially engaged at its lower end with the III cushion 20. However, as soon as the oil under pressure finds its way between the cushion 20 and the lower end of plunger 11, the latter will be raised so as to close said clearance space and engage the head of screw or bolt 12 with the lower end of rod or stem 8. As the cam 7 turns with the shoe or plate 10 riding on the base circle of said cam. the tappet will be constantly engaged with the cam and the rod or stem 8, and oil will find its way through openin or passage 21 onto the surface of the cam or minimizing wear. Upon continued rotation of cam 7 the projection of the latter will ride into engagement with the shoe or plate 10 and thereby effect lifting of the tappet and consequently cause lifting of rod or stem 8 for openin the associated valve, not shown. When this lifting action of the cam is had the opening 21 is less securely closed b the-cams'urface, and the liquld pressure 0 the liquid cushion between the plunger and the tappet body is partially relieved by a more pronounced flow of the oil through the passage 21 onto the cam 7. I This provides a film of oil on the cam surface so as to more thoroughly lubricate at a time when lubrication is more needed, and such film of oil will also serve to present a cushion-like medium between the contacting surfaces of the tappet body and the cam. At this time, the cam 7 will be starting upon its retreating period of movement for allowing the tappet and the push rod or stem to lower. This lowering action is effected and accelerated by the closing spring of the valve which tends to force the plunger 11 dow'nwardly into the valve body 9 as allowed by the reliefof pressure through the opening 21. Consequently, the tappet will automatically shorten dnnng its lowering movement for insuring permission of complete closing of the valve of the engine. As soon as the tappet completely lowers it will have been shortened to its extreme extent, at which time the lower end of the plunger 11 will contact the cushion 2-0 so that any likely shock is absorbed. The parts are then disposed for a new cycle of operation as described above.
oil between the cushion 20 and the lower end of plunger 11. Naturally, considerable of the oil fed to the groove 17 will find its way between the cont-acting surfaces of the guide 5 and the tappet body 9 so that lubrication is had at this point for preventing wear of these parts.
The plunger 11 may be substituted for the plunger 11 of Figure 5 in valve operating mechanism wherein the elements 12 and 13 are not employed. In such instances, the plunger is not interiorly threaded and the push rod or valve stem 8 constitutes the valve lifting member and is extended into the plunger so as to directly contact with the lower end of the latter.
From the foregoing description .it is believed that the construction and operation as well as the advantages of the present inven tion will be readily understood and appreciated by those skilled in the art.
Minor changes may be made without departing from the spirit and scope of the invention as claimed.
What I claim as new is 1. A self-adjusting tappet forpush rod operating mechanisms, including a pair oftelescopically and slidably associated members, means to supply oil under pressure between said tappet members for providing a liquid cushion therebetween and lengthening the tappet for maintaining constant contact o f the tappet with the cam and the push rod, said tappet having a longitudinal opening through the lower end thereof to allow the oil to flow from between the tappet members to a point between the tappet and the cam and to partially relieve the liquid. pressure of the cushion during the retreating movement of the cam whereby the tappet is allowed to shorten for permittin complete return movement of the push rodi 2. A tappet device for push rod operatin mechanisms, wherein the tappet is interposed between an operating cam and the push rod,
.to automatically partially relieve the liquid pressure ofthecushion during the retreating movement of the cam, whereby the tappet is allowed to automatically shorten for permitting complete return movement of the push rod, and an elastic cushion interposed between the tappet members for absorbing shock incident to sudden shortening of the tappet.
3. A self adjusting tappet for a push rod operating mechanism, comprising a pair of telescopically and slidably associated tappet members, means to supply oil under pressure between said tappet members for providing a liquid cushion therebetween for lengthening the tappet to maintain constant contact of the tappet with the cam and push rod, said tap-pet having a longitudinal opening through the lower end thereof to allow the oil to flow from between the tappet members to a point between the tappet and the cam and to partially relieve the liquid pressure of the cushion during the retreating movement of the cam whereby the tap-pet isallowed to shorten to permit complete return movement of the push rod, one of said tappet members comprising a centrally bored body having a cylindrical exterior bearing surface in the lower end of which said longitudinal opening is formed, and the other tappet member comprising a plunger slidably fitted-in the tappet body and having a closed lower end.
4. In combination, a guide, a tappet vertically slidable in said guide and comprising a pairv of telescopically and slidably associated members, a lifting cam engaged. with the lower end of the outer one of the tappet members, arranged to be engaged by the upper end of the inner one of said tappet members, and means for continuously supplying oil under pressure between said tappet members to provide a liquid cushion therebetween and to lengthen the tap-pet for maintaining engagement of the tappet members with the cam and the valve lifting member and for simultaneously supplying the oil between the cooperating surfaces of the guide and the tappet and the cooperating surfaces of the cam and the tappet, said oil supplyin means between the connecting surfaces of the tappet and the cam constituting means for relieving the pressure of the liquid cushion between the tappet members upon retreating movement of the cam and the lowering of the tappet and valve lifting member.
5. In combination, a guide, a tappet vertically slidable in said guide and comprising a pair of telescopic-ally and slidably associated members, a lifting cam engaged with the lower end of the outer one of the tappet members, a valve lifting member arranged to be engaged by the upper end of the inner one of said tappet members, and means for continually supplying oil under pressure between said tappet members to provide a liquid cushion therebetween to lengthen the tappet for maintaining engagement of the members with the cam and valve lifting member and for simultaneously supplyin the oil between the cooperating surfaces of t e guide and the tappet and the cooperating surfaces of the cam and the tappet, said oil supplying means comprising an oil pressure line communicating with the bearing opening of the tappet guide, said outer tappet member being provided with an external annular groove and said inner member being reduced at the lower end, the tappet member having the external annular groove having transverse apertures placing the groove in communication with the space provided between the tappet members by the reduced end of the other member whereby constant communication is had between the oil pressure line and the space between the tappet members.
6. A tappet device for push rod operating mechanism, wherein the tappet is interposed between an operating cam and the push rod, comprising a pair of telescopically associated members, a bearing guide designed to receive said members, one of said members being designed to rest upon an operating cam and the other being designed for connection with the push rod, and means for forcing a liquid under pressure between the inner end of the inner one of said members and the outer member to lengthen the tappet to maintain constant contact between the same and the cam and push rod, and means for relieving the pressure through that surface of the tappet member against which said cam bears,
at certain periods during the rotation of the cam.
In testimony whereof I aifix my signature.
WILLIAM A. SEAMAN.