US 3470983 A
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Description (OCR text may contain errors)
Oct. 7, 1969 s. F. BRIGGS LIGBTWEIGHT VALVE LIFTER Original Filed July 21, 1965 a Z; Em Na L f E WM I. h a a Z 5 12 ATTORNEY-S United States Patent 3,470,983 LIGHTWEIGHT VALVE LIFTER Stephen F. Briggs, P.0. Box 1617, Naples, Fla. 33940 Continuation of application Ser. No. 473,606, July 21, 1965. This application July 3, 1968, Ser. No. 747,002 Int. Cl. F01m 1/00; F16n 29/00; F011 1/1116 US. Cl. 184-6 Claims ABSTRACT OF THE DISCLOSURE This application is a continuation of my abandoned application 473,606, filed July 21, 1965. I
This invention relates to a lightweight valve lifter.
In my companion application for US. Patent Ser. No. 427,683, filed Jan. 25, 1965, now US. Patent No. 3,299,986, I illustrated diagrammatically a generally conventional valve operating system in which a cam actuates a valve lifter to transmit motion through the push rod and overhead rocker arm to a valve stem to open the valve against the bias of the valve spring.
The valve spring is required to have sufficient bias to cause the valve lifter to remain in contact with the valve cam so that the contour of the cam will accurately control the valve position. At high engine speeds, very great spring pressure may be required to accomplish this objective because of the momentum imparted to the lifter and push rod by the cam when it acts on the lifter in a valve opening direction. The greater the mass of the moving parts, the greater will be the required spring pressure. The increased spring pressure, in turn, brings about a tendency for increased wear between the cam and the cam follower. To reduce this wear, the lifter or cam follower is commonly made of very hard metals, with consequent tendency to increase the weight of this part. The increased weight may require further increase in spring pressure. By-reducing the weight of the lifter and at the same time providing adequate resistance to wear, the spring pressure can be reduced with the result that the whole system will operate more quietly and with less likelihood of trouble dueto wear.
It has been found that a die casting interlocked with a wear-resisting cam follower shoe or insert has many advantages because it is not only light in weight but may provide its own thrust bearing for the pusli'rod and may be adjusted as to its alloy composition to satisfy all metallurgical requirements. Accordingly, the present invention contemplates that an extremely hard insert or shoe designed to function as a cam follower will be prefabricated to be interlocked unitarily with a die casting into which the insert is cast. A light peripheral grinding of the exterior surfaces of the composite follower may be employed to render the exterior lateral bearing surface entirely cylindrical to fit the bore in which it reciprocates.
As a means of providing a thrust bearing surface for the push rod, the present invention contemplates any one of three arrangements. According to the preferred construction, the push rod has a convex or generally ICC a complementary bearing surface through which a lubricating duct opens. In a second construction, a separately prefabricated hardened ferrous insert is placed in a cavity prepared in the die casting to provide a thrust bearing surface for the push rod. In a third arrangement, the prefabricated hardened insert which serves as the cam follower has an extension upwardly in the die casting and is socketed to provide the push rod thrust bearing.
In all of these constructions, lubrication is effected through the push rod thrust bearing surface of the lifter. Because it is undesirable either to over-lubricate or underlubricate, it is something of a problem to provide just the right amount of lubrication. In the preferred arrangement herein disclosed, the valve lifter has an exterior annular channel or gallery communicating with the oil pressure line. From this gallery, a duct so shallow that it is hardly more than a scratch on the outer surface of the lifter extends downwardly either directly axially, or with helical inclination, to communicate through a generally radial duct with an axial opening through the push rod hearing. The shallow groove provides the necessary restriction to exclude excess oil. Yet it is free from the clogging to which a port of comparable cross section would be subject. The movement of the lifter in its bearing will wipe from the groove any foreign matter which might otherwise tend to lodge therein.
In the drawings:
FIG. 1 is a view in axial section through a lifter embodying the invention, portions of the cam and cam shaft and push rod and the engine casting being illustrated.
FIG. 2 is a view'in perspective showing the lifter per se.
FIG. 3 is a detail view taken in cross section through the lifter in the plane indicated at 33 in FIG. 1.
FIG. 4 is a view in axial section through a modified lifter.
FIG. 5 is a view similar to FIG. 4 showing another modified embodiment in section.
The engine casting is fragmentarily illustrated at 6. It includes a bore at -8 in which the lifter generically designated by reference character 10 is axially reciprocable, being subject to actuation and control by the cam 12 on cam shaft 14, to which it is held by the valve spring (not shown herein). The lifter includes a die cast body 16 and an external cam follower shoe or insert 18 which may conveniently be formed with a head portion 20 and a restricted neck portion 22 about which the lightweight body 16 is molded by die casting for the permanent and unitary retention of the cam follower insert 18 in body 16. The bearing surface 24 of the cam follower shoe 18 is held tightly against the peripheral surface of cam 12 by bias communicated to it through the push rod 26.
The push rod 26 requires very little pivotal movement with regard to the lifter 10. Such movement as is necessary is readily accommodated by the provision of a convex radially enlarged or bulbous generally spherical head 28 for which the die cast body 16 of the lifter has an integral portion providing a socket with a bearing surface at 30 complementary to the bearing surface of head 28.
To provide lubrication for the lifter 10 and for the universally pivoted connection of they push rod therewith (as well as the rocker arm above) oil transferring means is provided whereby oil under pressure is delivered by the engine oil pump (not shown) through the oil pressure line 32 to an annular gallery at 34. In the instant device, this happens to be formed in the lifter itself, rather than in the guide wall of bore 8. The gallery shown in a chanspherical head for which the die casting itself provides nel"externa1ly encircling the periphery of the lifter. A
very shallow groove 36 leads from the channel or gallery 34 to a duct 38 extending radially inwardly in the lifter body 16 and communicating with an axial duct 40 that leads upwardly through the bearing 30 not only for the lubrication of this bearing but for the transmission of oil upwardly through the axial duct 42 with which the push rod is provided for the lubrication of its upper end bearing with the rocker arm (not shown herein).
As explained, it is unnecessary that the duct 38 ever register with the pressure line 32. It is even undesirable for it to communicate directly with the channel or gallery 34 by an oil communicating passage of any substantial size. The shallow groove 36, which is hardly more than a scratch, and the depth of which can be predetermined to meet the requirements of any given engine, will convey sufiicient oil into the bearing to meet all requirements. As shown, the groove 36 extends axially in a vertical direction but it will be understood that if more restriction is desired, the direction of this groove may have a circuitous component. However, it is deemed significant that a very substantialcomponent of its direction is axial because its cross section is so slight than any foreign matter in the oil which would tend to clog this duct is wiped out because the duct 36 takes the form of an open groove exposed to the wall of the bearing bore 8 in which the lifter is reciprocable.
In the construction shown in FIG. 4, the cam follower insert 180 has a hardened bearing surface at 24 comparable to that shown in FIG. 1 but it has a different means of fixing it in the die cast body 16 of the lifter 100. The performed hardened cam follower may have an upwardly extending annular flange at 44 with a groove at 46 into which the die cast metal of body 16 flows when the die casting is made. With the flange 44 there is a cavity at 48 which also becomes filled with the die cast metal.
The channel or gallery 34 and the groove 36 and ports 38 and 40 are unchanged but there is a hardened ferrous metal insert at 50 put into a complementary socket 52 in the die cast body and formed to receive the convex bulbous head 28 of the push rod 26. The die cast body 16 has a generally cylindrical interior cavity 54 through which the insert 50 may be inserted to a seat as shown. The head 28 of the rod and the insert 50 of the body 16 provide the rod body with complementary bearing surfaces. The insert has a central duct 58 registering with the duct 40 bored into the die cast body to convey the lubricant through the insert 50 to lubricate the joint between the insert and the head 28 of the push rod and to provide lubricant for passage up the duct 42 of the push rod.
In the construction of FIG. 5, the hardened bearing insert 182 has a central stem at 60 with an annular groove at 462 comparable to that shown at 46 in FIG. 4 about which the die cast metal of body 16 is interlocked. At the upper end the stem 60 of the hardened insert at 182 is terminally exposed in the body cavity and integrally provided with a bearing surface 62 for the convex head 28 of the push rod 26. In this construction, it is necessary to provide the radial duct 38 in a position where it will register with a complementary duct 64 in the hardened insert, the insert also being provided with an axial duct at 66. These ducts 64 and 66 will become filled with the die casting alloy during the operation in which the insert 182 is die cast into the follower body and will, therefore, have to be bored out before the follower is assembled to the push rod and put into use.
1. In an engine, the combination with means providing a valve lifter bearing, of a valve lifter reciprocably mounted in the bearing and comprising a die cast body of lightweight alloy, and a terminal bearing shoe of highly wear-resistant material interlocked with and in unitary permanent connection with said body, the shoe having a neck portion of reduced radius extending into the body and having a head portion of larger radius than the neck portion and about which the body is molded to provide the said interlocked permanent connection.
2. A combination according to claim 1 in which said body has a cavity opening axially away from said shoe, the body being provided at the bottom of said cavity with a push rod bearing surface, together with a push rod having a terminal portion complementary to said surface and engaged therewith.
3. A combination according to claim 2 in which the terminal portion of the push rod is convex and radially enlarged as compared with the portion of the push rod coniiguous thereto, the said bearing surface being formed directly on the die cast body and being concave complementary to the terminal portion of the push rod.
4. In an engine, the combination with means providing a valve lifter bearing, of a valve lifter having a push rod bearing and reciprocably mounted in the first bearing and comprising a die cast body of lightweight alloy, and a terminal bearing shoe of highly wear-resistant material in permanent connection with said body, the means providing the valve lifter bearing having an oil pressure duct opening through said first bearing surface and the said valve lifter body having a groove of minute cross section communicating with said duct to receive oil therefrom, said groove opening into a cavity with which the body is provided and which extends toward the center of the body and communicates with the push rod bearing.
5. In an engine, the combination with means providing a bearing bore for a valve lifter, a valve actuating push rod, a valve cam; a litter engaged by the push rod and comprising a die cast body reciprocable in the bore, and a cam follower shoe integrally connected with the body and bearing on the cam, the body having an interior cavity opening axially away from said shoe and into which the push rod extends, the body and push rod having complementary bearing surfaces in mutual. engagement and being provided with oil ducts in mutual communication through said bearing surfaces, the oil duct of the body opening inwardly from a side portion thereof, the means providing the bearing bore having an oil pressure duct opening into said bore and the lifter body having oil transferring means which includes a shallow groove of limited cross sectional area disposed in its outer surface and extending generally axially of the bore into communication with the said duct of said body which communicates with the registering duct of said push rod.
6. A combination according to claim 5 in which a hardened insert for which the body is provided with a seat at the bottom of its said cavity which provides the bearing surface with which the push rod is engaged, the said bearing surface of the insert being concave and the bearing surface of the push rod having a complementary convex contour.
7. A combination according to claim 5 in which the said shoe has a head portion and a neck portion and the die cast body is engaged about the neck portion and has the head portion cast into the body.
8. A combination according to claim 5 in which the said shoe has a stem cast into the body and terminally exposed in said cavity and integrally provided with the bearing surface with which said push rod is engaged.
9. In an engine, the combination with means providing a valve lifter bearing, of a valve lifter reciprocably mounted in the bearing and comprising a die cast body of lightweight alloy, and a terminal bearing shoe of highly wear-resistant material interlocked with and in unitary permanent connection with said body, the shoe having a neck portion of reduced radius extending into the body and about which the body is molded to provide the said interlocked permanent connection.
10. A combination according to claim '9 in which said body has a cavity opening axially away from said shoe, the body being provided at the bottom of said cavity with a push rod bearing surface, together with a push rod having a terminal portion complementary to said 3,073,292 1/1963 Behnke et a1. surface and engaged therewith. 3,151,501 10/1964 Hicks.
11. A combination according to claim 10 in which the terminal portion of the push rod is convex and radially FOREIGN PATENTS enlarged as compared withthe portion of the push rod 5 1,020,633 11/1952 France. contiguous thereto, the said bearing surface being formed 290,507 5/1923 Great Britaim directly on the die cast body and being concave complementary to the terminal portion of the push rod. FRED C. MATTERN, JR., Primary Examiner References Cited 10 M. ANTONA-KAS, Assistant Examiner UNITED STATES PATENTS S L 1,840,633 1/1932 Morehouse. 123 90 1,963,614 6/1934 Edwards.