US2840063A - Hydraulic valve lifter - Google Patents

Description

June 24, 1958 w. J. PURCHAS, JR 2,840,063

' HYDRAULIC VALVE LIFTER Filed June 17, 1955 INVENTOR ATTORN Y United States Patent HYDRAULIC VALVE LIFTER William J. Purchas, Jr., Grand Rapids, Mich., assignor to General Motors Corporation, Detroit, Mich, a corporation of Delaware Application June 17, 1955, Serial No. 516,112

3 Claims. (Cl. l2390) This invention relates to hydraulic valve lifters for operating poppet valves and the like of internal combustion engines.

It is the principal object of the invention to provide a hydraulic valve lifter of low cost design employing generally cup shaped cylinder and plunger members in telescopically nested relation defining a pressure chamber between their closed ends in which a spring acts in compression to expand the chamber and thereby take up lash in the mechanism.

A more specific object is to provide such a lifter in which the outer cup shaped part is fabricated from a steel tube and an end closing foot piece of cast iron, steel, powdered metal, or alloy ironbrazed or otherwise permanently bonded to the end of the tube and having a portion extending inwardly of the tube serving to pilot the two parts during assembly, to socketably locate vthe spring, and to provide a stop shoulder limiting inward movement of the plunger.

These and other objects and advantages of the invention will be more clearly understood from the following description of one preferred embodiment, having reference to the drawing, wherein:

Figure 1 is a transverse sectional view through a portion of an internal combustion engine showing its valve operating mechanism including a lifter in accordance with the invention. 7 I

Figure 2 is an enlarged sectional view taken longitudinally through the valve lifter and associated engine structure of Figure 1.

Suitably journaled in the cylinder block and crankcase 1 of the engine and driven by its crankshaft (not shown) is a camshaft 2 having a cam surface 3 in operative engagement with the valve lifter 4 of the invention. Lifting motion imparted to the lifter by rotation' of the cam 3 is transmitted by the push rod -5 "to a rocker 6 mounted to oscillate about a shaft 7 supported from the engine cylinder head 8, the rocker in turn driving the poppet valve 9 against a valve return spring 10. A piston 11 is shown in its working cylinder 12 of the engine, and the poppet valve 9 controls communication between the engine combustion chamber 13 and a port 14.

The valve lifter as shown in Figure 2 has an outer cup shaped body or cylinder assembly formed of a steel tube 15 and a cast iron or alloy iron cam engaging foot piece 16 constituting an end closure member for that end of the tube. The tube 15 has an outer diameter slidably fitting a bore 17 provided therefor in the crankcase 1 of the engine above the camshaft, the outer pe riphery of the tube being relieved by an annular groove 18 of sufiicient width to maintain continuous registry with an oil feed port 19 served by a gallery 20 connected with the pressure lubricating system of the engine. The internal periphery of the tube has a bore 21, also relieved by an annular groove 22 which connects with the groove 18 by one or more side wall ports 23, and in close telescopically sliding fit in the bore 21 is a cup shaped plunger 24 whose external periphery is relieved by an annular groove 25. This groove 25 is made sufficiently wide to have continuous communication with the tube internal groove 22 and is connected to the reservoir chamber 26 internally of the plunger by one or more plunger side wall ports 27. Oil from the engine lubricating system may therefore flow at all times into the plunger reservoir from the gallery via the port 19, groove 18, port 23, oil groove 22, plunger groove and port 27. The tube internal groove 22 overlaps the upper edge of the plunger groove 25, and the latter overlaps the lower edge of the tube internal groove 22, sutficiently so that in all relative positions of the plunger and tube no oil sludge or varnish-like deposit on their sliding surfaces opposite these grooves will prevent inward movement of the plunger under the force of the valve return spring 10. Above the lowermost or innermost end of the plunger the tube is also relieved by a second internal groove 28 for the same reason, and the lower end of this groove is open at all times to the pressure chamber 29 between the plunger and foot piece 16.

Connecting the pressure chamber 29 with the reservoir 26 in the plunger is a passage 30 whose lower end is normally closed by a check valve shown in the form of a ball 31. Enclosing the ball is a generally cup shaped retaining cage 32 whose open end is externally flanged and slotted as at 33 to abut the plunger and accommodate passage of oil between the passage 30 and the pressure chamber 29 when the ball is displaced from its seated position shown. A small biasing spring 34 between the ball and the bottom of the cage tends to maintain the ball seated. The bottom end wall of the plunger is recessed to receive the cage flange 33 within a depending annular skirt portion 35. The internal periphery of this skirt portion has a tight frictional fit' with the lateral extremities of the slotted cage flange to retain the cage in assembly with the plunger during its installation or removal from thetube. Seated against the cage flange is one end of a coil compression spring 36 which reacts against the foot piece in urging the plunger outwardly of the tube.

The foot piece 16 includes a bottom disk shaped portion 37 which abutsthe-bottom end face of the tube and is permanently bonded thereto as by inserting a ring of brass therebetween prior to assembly and then using .the elevated temperature of subsequent .carborizing or other heat treatment to fuse the brass to obtain the brazed joint 38. integral with the disk shaped portion 37 is an annular portion 39 having an outer diameter to slidably fit the internal periphery at the lower end of the tube and pilot the foot piece centrally thereof during the assembly and brazing operation. This annular portion 37 also provides a well in which the bottom end of the plunger return spring 36 is socketably seated, and the upper end 40 of this annular portion provides a shoulder engageable by the plunger skirt portion to limit extreme inward movement of the plunger. Such stopping of the plunger movement inwardly of the tube must be provided for, because during a prolonged shutdown of the engine while the lifter is held elevated by the nose of the cam 3 the plunger will leak down under the force of the poppet valve return spring 10 as oil gradually escapes from the pressure chamber 29 through the limited clearance space between the plunger and the bore of the tube. Only sufiiceint axial spacing exists between the opposing ends of the annular and skirt po'rtions 39 and 35 to accommodate the normal operative range of plunger movement within the tube, and engagement of these. portions takes place under the aforementioned extreme leak down condition in advance of either the plunger return spring 36 being fully collapsed Patented June 24, 1958 push' rod tolubn'cate the valverockeri 6. The push rod seat member43 is formed with a flangeportion 46 overlying the upper open end of the plunger; and has its l apertured lower end extending somewhat into the p'lunger to locate it laterally thereof. Between the flange 46 and the upper end of the plunger, and forming a press fit between the sidewalls of the plunger and the seat member 43, is a sheet metal stamping 47 which serves to retain a wafervalve 48 in controllingrelation' with the passage 44; The" bottom end face 49 of the push rod seat member ismade fiatand the opposing face 50 of the wafer valve 48' is made cylindrical to cooperate with each other in obtaining a variable restriction of the passage 44. The lower end of the stamping ,47 is flanged inwardly at a sufficient distance below the fiat seat member face 49 toaccommodate' freemovement of the wafer valve into and outof abutment with the seat member in response to bothoil' pressurein the reservoir tending to raise the wafer valve, and to inertia force of the wafer valve. Whenthe'wa fer valve is in abutment with the flat face 49 only a restricted rate of flow up the push rod from the reservoir is obtained, and this rate of flow is substantially increased whenever the wafer valve is displaced inwardly of the plunger. The retaining flange provided by the stamping also has its upper surface 51 made flat to cooperate with the cylindrical bottom face 52 of the wafer valve in preventing a full closure of the bottom opening 53 and the stamping.

While only a single preferred embodiment of the invention has been disclosed, it is appreciated that nu merous minor changes in the construction and arrangement of the parts may be made without departing from the spirit and scope of the invention as defined'in the following claims.

' I claim: v V

1. In a hydraulic valve lifter having ,a cup shaped cylinder, 9. plunger reciprocable'in the cylinder and defining a hydraulic pressure chamber in the bottom end of the cup, and a spring acting between the cylinder and the plunger to enlarge said chamber, said cylinder being of fabricated construction including a tube and a separate end closure memberfixed thereto, said member having a generally disk shapedportion abutting the adjacent end of the tube and an integral ring-like portion ofredu'ced peripheral dimension extending into the tube to form a stop for the pluner, said last named portion embracing and locating the spring centrally of the axis of said tube.

2. In a hydraulic valve lifter having inner and outer cup shaped cylinder and plunger means in slidably nested relation defining a hydraulic pressure chamber between their respective bottom walls, and a coil compression spring within said chamber biasing the plunger means outwardly of the cylinder means, said cylinder means being of two-piece construction consisting of a tubular member extending beyond the chamber end of the plunger means and a closure member for said end of the tubular member, said closure member having a dis-l: shaped portion underlying and permanently bonded 'to the adjacent end face of the tubular member, and

having a hollow annular portion extending into and closely fitting the internal walls of the tubular member adjacent said end face, said spring having one end operatively abutting the plunger means and its opposite end socketed in said annular portion, said plunger means having a dependingskirt portion embracing its end of the spring and abuttable with said annular portion of the closure member to prevent compression of the spring to a fully collapsed condition.

3. In a hydraulic valve lifter, a cup shaped body assembly consisting of a tube and a separate cam engageablefoot piece permanently bonded thereto and defining the bottom of the cup, said foot piece having its tube facing end formed with a hollow annular portion extending into and closely fitting the internal periphery of the tube, a shoulder surrounding said annular said anular' portion and underlying the adjacent end of the tube, and a central spring seat defined laterally by the inner periphery of said annular portion, a cup shaped plunger sliclably reciprocable in said tube having its bottom end formed with a cylindrical skirt opposite said annular portion and a spring, seat laterally defined by the inner periphery of said skirt portion, and a plunger return spring interposed between said spring seats, said annular and skirt portions being abuttable with each other to limit plunger movement inwardly of said body assembly in advance of said spring being fully collapsed.

References Cited in the file of this patent UNITED STATES PATENTS

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