US2874685A

US2874685A - Hydraulic valve lifter

Info

Publication number: US2874685A
Application number: US530849A
Authority: US
Inventors: Gerald D Line
Original assignee: Eaton Manufacturing Co
Current assignee: Eaton Corp
Priority date: 1955-08-26
Filing date: 1955-08-26
Publication date: 1959-02-24
Anticipated expiration: 1976-02-24

Description

Fig. I

a. D. VLINE HYDRAULIC VALVE LIFTER Filed Aug. 26,. 1955 2 Fig. 4

IN VEN TOR.- GERALD D. LINE I BY v 'ATTOR EYS 2,874,685 Patented Feb. 24, 1359 HYDRAULIC VALVE LIFTER Gerald'DrLine, Royal Oak, Mich., assignor to Eaton Manufacturing Company, Cleveland, Ohio, a corporation of Ohio Application August 26, 1955, Serial No. 530,849

Claims. c1.123 90 This invention relates to tappets and more particularly to hydraulic tappets for internal combustion engines.

Broadly the invention comprehends the provision of a hydraulic tappet or valve lifter for use in the valve gear train of internal combustion engines and which incorporates therein novel fluid passageway communication be tween the body and plungerof the tappet by reason of providing a body of stepped bore construction, elfective in association with a grooved or surface relieved portion of the plunger for preventing the formation of garnish deposits between the plunger and body tending toward the malfunctioning thereof;

Whileit is recognized that a great number of communicating passageway constructions have been devised in connection with hydraulic tappets for serving a like purpose, such as disclosed in U. S. Patents 2,672,133 and 2,665,669, there is ample room for improvement thereover providing for greater ease of manufacture as well as more effective operation. 7 l

The herein devised hydraulic tappet although directed specifically at the accomplishment of a like purpose as previous hydraulic tappets that have found great favor in the automotive industry provides structural advantages thereover and among its objects are/the following: a

a. The elimination of an internal annular groove in the body of. the type generally required for varnish relief;

b. Provision of a stepped bore in the bodyproviding hydraulic fluid communication between the plunger and body by association therewith with openings through the cylindrical wall of the body and an annular relief pro.- vided externally of the plunger;

0. Provides for the reciprocable fit clearance of the socket of the plunger in the large diametered bore .of the body so. as toolfer controlled fluid leakage therepast while simultaneously providing an air escape path thus making the tappet faster quieting;

.d. Requires a shorter length. of bore to which the plunger proper has to be selectively fitted thus making for easier manufacture;

e. Permits of a bottoming of the socket at the junction of the bores of the body thereby eliminating a shoulder pear from the following description taken in connection with thedrawings forming. a part of the specification, and in which:

Fig. 3 is a cross-sectional view of a modified form of "the tappet of Fig; '1; and, I

Fig. 4 is a further modified form of the tappet of Fig. 1. I

' Referring to the drawings. for more specific details of the invention 10 represents generally a hydraulictappet forming an element of a valve' geartrain, for internal combustion engines, and adapted to be interposed between the cam and pushr'od of the gear train. a 10 Tappet 10 comprises a hollow cylindrical body 12 closed at one end 14, a hollow plunger or piston 16 reciprocable in the body, a cap or socket 18, seated on an open end of the plunger 16, reciprocable in the body, a flat check valve 20 supported within a valve cage 22 for engagement with an end of the plunger axially opposite from the cap 18, and a coil spring 24, arranged in the bottom of the body, axially biasing the plunger outwardly thereof.

The body 12 provides internally thereof a series of different sized

bores

26, 28 and 30, an annular groove 32 intermediate bores 28 and30 providing a shoulder 34 and an annular groove 36 arranged near the open end of the body. g

A spring clip 38 is appropriately held in groove 36 and serves to limit the outward axial movement of the plunger 16 and cap 1 8 whereas shoulder 34 is adapted to beengaged by a shoulder or end surface 40 of the plunger so as to limit its opposite axial extent of movement relative to the body.

Withcap 18 seated on the open end of plunger 16 a reservoir or'low pressure chamber 42 is provided internally of the plunger having'communication exteriorly thereof at the valve end of the plunger through a central fluid port or passage 44 and at the cap end of the plunger through a series of circumferentially spaced openings 46 formed by the provision of a series of slots on the extremity of the plunger adjacent the cap. In addition Fig. 1 is a cross-sectional view of a hydraulic tappet- I embodying the basic invention taught hereby;

Fig. 2 is a cross-sectional view taken substantially along lines 2'2 of Fig. 1; i

to openings 46, an annular relief or recess 48 is provided onithe external surface of plunger 16 in communication with openings 46. A central opening 49 is provided in cap 18and servesa's a passageway for the feeding of hydraulic fluid to the socket of cap 18 whereby in asso-.

ciation with mechanism, not shown, such as a pushrod, hydraulic fluid canbe conveyed to other parts of the valve gear train requiring lubrication.

A high pressure chamber 50 is provided between the valve end of the plunger and the closed end of the body 12 and communicates with low pressure chamber 42 through port 44 in plunger 16. Valve 20 is normally maintained in valve seated positionon plunger 16 over port 44 by a light coil spring 51 axially disposed between valve cage 22 and valve2 0 with the cage in turn having a press fit'coupling arrangement on an axially extended portion of plunger 16. Coil spring 24 which serves to the plunger.

Hydraulic fluid to be supplied for the operation of the tappet is fed from an external source through communicating external groove 52 on body 12 and port 54 extending through the body in communication with groove 52 and stepped bore 26.

By reason of fitting the cap into bore 26 of the body with predetermined clearance of say between .001 and .0035 for conventional sized tappets employed in passenger automotive engines controlled clearance is had for leakage of fluid therepast while at the same time permitting the escape of air which might become entrained in the hydraulic fluid of the tappet. Further in view of the cap fitting in bore 26 the bore 28 diameter to which the plunger is selectively fitted is held to a minimum of axial length thus making for easier manufacture in the insuring of selective fit between the body and plunger.

With the plunger bottomed; as disclosed by Fig. 1 wherein shoulder 40 of the plunger axially abuts. shoulder 34 of the body, the end extremity of annular relief 48 and openings are in direct communication with the annular space 56 provided between the body, cap and plunger by reason of stepped bore 26, which space in turn is supplied operating hydraulic fluid from an external source through port 52 of the tappet body.

It is to be recognized that although the plunger is depicted in Fig. l in bottomed position in the body, that under normal operation it functions, depending upon conditions of expansion and contraction of the valve gear train and its own normal compensating operation, to reciprocate in the body between its end axial limits as determined by shoulder '34 and spring clip 38. As such, continuous and full fluid registration is had for the supply of hydraulic fluid to the chamber 42 and thence through opening 49 or to the high pressure chamber of the tappet as controlled by the valve 20, and the annular relief 48 and stepped bore 26 have such overlapping relation and relative movement so as to prevent the formation of varnish deposits from interfering with the tappet operation. In viewing the structure of Fig. 1 it will be noted that should varnish residue build up on the exposed surface of bore 28 when the tappet is idle, the edge 58 of relief 48 will serve to wipe said varnish residue from bore 28 upon renewed actuation of the tappet.

Fig. 3 differs from the structure of Fig. 1 solely in the provision of a modified form of cap 18 from that of 18, said cap 18 having communicating passages 49a and 49b therein, which passages provide communication, by way of a flat or recessed external 49c portion of cap 18, between. space 56 and the socket of the cap.

The structure of Fig. 4 is at variance with Fig. 1 as regards the provision of

stepped bores

26 and 28 for body 12 and the elimination of bore 39 of Fig. 1 whereby cap 18 is adapted to seat upon a shoulder 26a provided at the junction of

bores

26 and 28 In so providing the shoulder 26a at a predetermined location relative to the cap size and the permitted reciprocative movement of the cap and plunger to tappet body 12 the shoulder serves as an inward movement limiting. position for the cap as actuated by valve gear mechanism adapted to be in engagement therewith. As a result of this provision it is possible to eliminate the bore 30 provided in the structure of Fig. 1 while at the same time sealing olf communication between port 54 and the interior of body 12 when the tappet is bottomed with cap 18 seated on shoulder 26a. With the cap so bottomed an immediate sealing of the oil within the body and plunger is had such that the oil cannot drain back through port 54. It will thus be apparent that by trapping the oil in the body and plunger that said oil will be available for starting purposes after engine shutdown and thereby provide quicker quieting time upon engine operation resumption.

While this invention has been described in connection with certain specific embodiments, the principle involved is susceptible of numerous other applications that will readily occur to persons skilled in the art. The invention, therefore, is limited only as indicated by the scope of the appended claims.

What I claim is:

1. A hydraulic tappet comprising a hollow cylindrical body closed at one end and having stepped bores, a piston mounted for reciprocation in one of the bores having a relieved external annular surface at one end thereof, and a passage therein providing communication between the relieved surface and a chamber formed between the other end of the piston and the closed end of the body, a cap in axial engagement on said one end of the piston mounted for reciprocation in another bore of the body adjacent the open end thereof, said bore of the body adjacent the open end thereof being larger in diameter than the bore in which the piston is reciprocable, said body having a port therein communicating with said bore adjacent the open end of said body, and said cap being operatively positionable to close off communication between said port and said bore and being longitudinally supported by said bore. I

2. A hydraulic tappet according to claim 1 wherein a shoulder is provided at the junction of the bores for the cap and piston and wherein the cap is axially engageable with the shoulder for limiting one axial extent of movement thereof.

3. A hydraulic tappet comprising a hollow cylindrical body closed at one end and having a plurality of stepped bores therein of progressively larger diameter starting at the closed end of the body, a plunger mounted for reciprocation in the innermost bore and adapted to have one axial portion thereof engageable with a shoulder provided at the junction of the bores, said plunger being relieved annularly peripherally at one end thereof axially spaced from said axial portion thereof and having passage means therethrough providing communication between the relieved end thereof and a chamber formed between its opposite end and the closed end of the body, a valve for controlling the passage means in the plunger, a port providing communication between said bores and the external wall portion of said body, a cap, engageable upon the end of the plunger that is relieved, mounted for recipprocation in the largest ibore adjacent the open end of the body, and said cap being longitudinally supported by said largest bore and operatively positionable to close 01f communication between said port and said bores.

4. A hydraulic tappet according to claim 3 wherein passage means is provided through the side wall of the body communicating with the largest bore.

5. A hydraulic tappet according to claim 4 wherein the relieved end of the plunger overlaps a portion of the largest bore.

6. A hydraulic tappet according to claim 5 wherein the passage means in the plunger includes at least one radial slot provided on the end extremity of the plunger adjacent the relieved end thereof.

7. A hydraulic tappet comprising a hollow cylindrical body closed at one end and having stepped bores therein, one being adjacent the open end of the body, and a smaller diametered one adjacent said one bore, a piston mounted for reciprocation in the smaller diametered bore and forming at one axial end thereof with the closed end of the body a high pressure chamber, said piston having an annular relieved surface adjacent the other axial end thereof axially spaced from the chamber and passage means therein providing communication between the relieved surface and the chamber, a cap, in axial engagement with said other end of the piston, mounted for reciprocation in the bore adjacent the open end of the piston, being longitudinally supported by and having such clearance with the confining wall of the piston bore in which it is mounted as to control hydraulic fluid leakage therepast while permitting the ready escape of air that may become entrained in the hydraulic fluid of the tappet, valve means for controlling the passage means in the piston and passage means in said body providing communication between the external portion of said body and said bores, and said cap being operably positionable to close off said last mentioned passage means.

8. A hydraulic tappet comprising a hollow cylindrical body closed at one end and having stepped bores, a piston mounted for reciprocation in one of the bores having a relieved external annular surface at one end thereof, oppositely disposed from the closed end of the body, and a passage therein providing communication between the relieved surface and a chamber formed between the other I end of the piston and the closed end of the body, a cap in axial engagement on said one end of the piston mounted for reciprocation in and longitudinally supported by another bore of the body adjacent the open end thereof,

said bore of the body adjacent the open end thereof being larger in diameter than the bore in which the piston is reciprocable, and spring means biasing the piston outwardly of the body, said Ibody having a port through its side wall communicating with said bore adjacent the open end of the body, and said cap being adapted to seat on a shoulder formed at the junction of the bores and close off communication between the port and bores in the body.

9. A hydraulic tappet comprising a hollow cylindrical body having a wall portion, a closed end portion and an open end portion, with said body having stepped bores, a piston having end portions, said piston being mounted for sealing reciprocation in one of said vbores and having a relieved external annular surface at one end thereof and a passage therein providing communication between said relieved surface and a chamber formed between the other of said ends of said piston and the closed end of the body, a cap in axial engagement with said one end of said piston mounted for sealing reciprocation in an- 10. A hydraulic tappet according to claim 9, wherein said passage means communicating with at least one of said bores, is adjacent the junction of the lbores.

References Cited in the file of this patent UNITED STATES PATENTS 2,665,669 Ellis Jan. 12, 1954 2,672,133 Etchells Mar. 16, 1954 2,689,554 Moser Sept. 21, 1954 2,700,965 Humphreys Feb. 1, 1955 2,760,470 Bergmann Aug. 28, 1956