US2845914A

US2845914A - Valve lifter cylinder and method of making same

Info

Publication number: US2845914A
Application number: US523288A
Authority: US
Inventors: Alfred H Cobo
Original assignee: Motors Liquidation Co
Current assignee: Motors Liquidation Co
Priority date: 1955-07-20
Filing date: 1955-07-20
Publication date: 1958-08-05
Anticipated expiration: 1975-08-05

Description

Aug. 5, 1958 A. H. COBQ VALVE LIFTER CLYINDER AND METHOD OF MAKING SAME Filed July 20, 1955 INVENTOR. 0

ATTOPNEY United States Patent VALVE LIFTER CYLINDER AND METHOD OF MAKING SAME Alfred H. Cobo, Grand Rapids, Mich, assignor to General Motors Corporation, Detroit, Mlch., a corporation of Delaware Application July 20, 1955, Serial No. 523,288

4 Claims. (Cl. 123-90) This invention relates to valve lifters for operating poppet valves and the like in response to movement imparted by an engine driven cam, and particularly to cylinders for such lifters of the so-called hydraulic type.

A design of such lifter which is in most common use today comprises a cup-shaped cylinder arranged upright on the cam of the engine and slidably fitted with a plunger which rests on a body of oil in the bottom of the cylinder and transmits lifting movements of the cam to the poppet valve or its operating push rod. A spring interposed between the cylinder and plunger acts to take up lash in the valve train following each lift stroke, with the result that the volume of the oil body below the plunger is increased, and additional oil for this purpose is allowed to pass into the lower end of the cylinder through a one-way passage in the plunger. This additional or make-up oil is contained in a reservoir either within or above the plunger. The bore of the cylinder has a close sliding fit with the plunger to permit a controlled leakage of oil from the lower end of the cylinder during each cam lift stroke, thereby providing a slight foreshortening of the lifter during each lift stroke to ensure its over-all length will not prevent full return movement of the valve or other device actuated by the lifter.

Experience in the operation of such lifters, especially those in which the reservoir is supplied from the engine lubricating system, has shown that varnish-like material and other foreign particles from the oil tends to deposit more readily on those slidably fitted surfaces of the plunger and cylinder bore which are not covered by the other. To prevent such deposits from becoming jammed or wedged between those surfaces and interfering with the necessary foreshortening of the lifter it has been the practice to relieve those portions of the cylinder bore and the guided surface of the plunger which would otherwise slidably engage the other as the plunger moves inwardly of the cylinder. Such relief of the cylinder bore is required adjacent its inner or closed end and has heretofore been accomplished by either undercutting that end of the cylinder bore with a suitable boring tool inserted through the open end of the cup, or by counterboring that end of the tube before attachment of the cam engaging foot. Such machining operations have increased the cost of such lifter cylinders, not only because of the time and tool expense involved, but as a result of wastage of metal which this method necessitates.

It is a principal object of this invention to reduce the cost of such a lifter cylinder by forming it of a plurality of concentric tubes and a foot portion, with the inner of the tubes terminating spacedly from the foot and the corresponding end of the outer tube being joined to the foot to thereby form such bore enlargement.

The formation of the side walls in this manner from a plurality of tubes has a further advantage in making such cylinders which are also to be provided with an external annular groove adapted to communicate with gether by the inner tube which forms the bore for the lifter plunger.

H The means for carrying out these and other objects of the invention will be more readily apparent from the following description, having reference to the drawing' wherein:

Figure 1 is a longitudinal sectional view through a hydraulic valve lifter having its cylinder constructed in accordance with the invention.

Figure 2 is a transverse sectional view taken substantially on line 2-2 of Figure 1.

Figure 3 is a view similar to Figure 1 showing the same lifter modified to provide the external annular groove about the cylinder between adjacent ends of two axially spaced outer tubes.

Figure 4 is a transverse sectional view taken substantially on the line 44 of Figure 3.

The lifter shown in Figures 1 and 2 comprises a cupshaped cylinder indicated generally by the numeral 1 in which a plunger 2-is slidably reciprocable and is adapted to rest on a body of oil contained in a pressure chamber 3 between the closed end Wall 4 of the cylinder and the plunger. A plunger return spring 5 is shown within this chamber 3 for biasing the plunger outwardly of the cylinder to take up lash between the engine cam (not shown) on which the cylinder rides and the engine valve or pushrod (not shown) which thrustably abuts the upper end of the plunger.

The plunger 2, in the particular design shown, comprises, a cylindrical tubular member 6 plugged at its opposite ends by a check valve seat member 7 and a push rod seat member 8. The interior of the plunger forms a reservoir 9 which supplies the pressure chamber 3 through a check valve controlled passage 10. The check valve controlling this passage is shown as a ball 11 retained within a cage 12 held in place against the seat member 7 by the plunger spring 5. A lighter coil spring 13 biases the ball to its seated position closing the passage 10. The upper or push rod seat member 8 is also shown as having a passage 14 through which excess oil supplied to the reservoir h may be metered under the control of a flutter valve 15 loosely retained in the lower end of the member 8 by a ring 16.

The plunger 2 is shown in its approximate mean operating position longitudinally of the cylinder 1, with the slidably guided outer surface 17 of the plunger extending well into the pressure chamber 3. In other words, the upper portion of the chmaber 3 surrounds the lower portion of the plunger guided surface 17 to a sufiicient height above the plunger lower end that even with the plunger positioned at the extreme upper end of its operative travel the bore 18 of the cylinder 1 is never exposed to the oil in the pressure chamber 3. Any suitable means, such as an outspringing snap ring 19 engaging a groove in the upper end of the bore 18, is provided for retaining the plunger and cylinder in assembly when the lifter is removed from the engine.

In accordance with the invention, the cylinder 1 has its side walls formed of concentric inner and outer tubes 20 and 21, with the lower end of the outer tube being permanently and sealingly joined to the imperforate cam engaging disk or end wall 4 as by brazing indicated at 22. As shown, this end wall piece is provided with an annular portion 23 extending into the outer tube to form a socket laterally locating the plunger return spring 5, and an abutment surface 24 which serves as a stop to limit extreme movement of the plunger inwardly of the cylinder. The inner tube 20 lines the outer tube 21 and treminates at its lower end 25 in spaced relation from the foot piece 4 to provide the same efiect as obtained in the prior art by the aforementioned enlargement of the bore 18. The two tubes 20 and 21 are fixed to each other and sealed against escape of oil from the pressure chamber 3, as by coating their interfitting surfaces with cooper or other suitable brazing material before assembly and then heating to effect a solid bond between them.

The particular lifter shown is of the side fed type, i. e., the reservoir 9 is supplied with engine lubricating oil conducted to the bore (not shown) of the engine in which the cylinder is reciprocally guided. For this purpose, the outer periphery of the outer cylinder 21 is provided with an external annular groove 26 adapted to maintain registry with a port in the cylinder guided bore, and connecting this groove with the interior of the plunger are aligned ports 27 and 28 in the respective tubes, overlapping internal and external grooves 29 and 30 formed in the bore 18 and the plunger external surface 17, and a port 31 in the plunger wall.

In the modified construction shown in Figures 3 and 4, the single outer tube 21 is replaced by two axially

spaced tubes

121 and 221, with the latter tube being connected to the cam engaging foot piece 4 at its lower end, and the axial space between the

tubes

121 and 221 defining the upper and lower extremities of the groove 126. The inner tube 20 is identical with that of Figures 1 and 2, and may be fixedly and sealingly bonded to the two outer tubes by copper brazing in the same manner, or by employing a sufliciently tight press fit between their respective interfitting surfaces and tack welding at various spaced points as indicated at 140. As will be appreciated, this form of my invention has the additional advantage over that shown in Figures 1 and 2 of eliminating the step of machining the cylinder external groove, while retaining the advantages of eliminating the necessity of machining to provide the necessary relief for the lower end of the cylinder bore 18.

I claim:

'1. In a hydraulic valve lifter cylinder member having a tubular portion and a cam engageable foot fixedly and sealingly connected to one end thereof, said tubular portion comprising concentric inner and outer tubes of difierent lengths secured together with the foot adjacent end of said inner tube being spaced endwise of said foot to form a radial enlargement of the bore of said tubular portion, said outer tube having an external groove intermediate the ends of said inner tube, said inner tube having a port communicating with said groove and open to the boreat a distance from said enlargement.

2. In a hydraulic valve lifter of the type having a cup- 4 shaped cylinder with a plunger axially reciprocable therein and defining a chamber for thrust transmitting fluid between the plunger and the end wall of the cylinder, said cylinder having its side walls constituted by a plurality of tubes including an outer tube defining the lateral extremities of said chamber and an inner tube lining said outer tube outwardly of said chamber, said plunger slidably fitting the bore of said inner tube and extending into said chamber throughout the operative range of movement of the plunger.

3. In a hydraulic valve lifter having a generally cupshaped cylinder, a plunger reciprocable therein and a body of fluid thrustably supporting the plunger from the end wall of said cylinder, said cylinder having its side walls constructed of a plurality of concentric tubes including an outer tube terminating sealingly and fixedly at one end with the cylinder end wall, and an inner tube lining said outer tube and spaced axially thereof from said end wall, said tubes being fixed and sealingly bonded to each other against escape of fluid therebetween from said body, said'plunger having a cylindrical external surface slidably fitting the bore of said inner tube adjacent said body and extending into said body beyond said bore throughout the normal operative range of plunger movement.

4. In a hydraulic valve lifter having generally cupshaped cylinder and plunger members in slidably nested relation defining a fluid pressure chamber between their respective end walls and a fluid reservoir interiorly of the plunger member, said cylinder member having its side walls constructed of a plurality of tubes of difierent lengths including two aligned outer tubes axially spaced from each other to define a receiving groove therebetween for fluid to be supplied to said reservoir from a source externally of the lifter, and an inner tube sealingly and fixedly interconnecting said outer tubes, said inner tube having a side port connecting its bore with said groove for the passage of said externallysupplied fluid, one of said outer tubes extending beyond the pressure chamber end of said inner tube and terminating fixedly and sealingly with the end wall of the cylinder member, said end of the inner tube being overlapped by the plunger member throughout the normal operative range of relative movement of the plunger and cylinder members.

References Cited in the file of this patent UNITED STATES PATENTS 2,178,732 Voorhies Nov. 7, 1939 2,652,038 Winkler Sept. 5, 1953 2,680,901 Kaiser June 15, 1954 2,689,554 Moser Sept. 21, 1954