US2595583A - Oil supply for hydraulic tappets - Google Patents

Description

y 6, 1952 c. E. JOHNSON 2,595,583

OIL SUPPLY FOR HYDRAULIC TAPPETS Filed Sept. 26, 1949 lnvEm-ow. CHARLES E. Jameson A'rronuevs Patented May 6, 1952 UNITED STATES PAINT FFICE OIL SUPPLY FOR HYDRAULIC TAPPETS Application September 26, 1949, Serial No. 117,832

4 Claims. 1

This invention relates to improvements in hydraulic tappets. In such tappets liquid, such as oil, must be supplied to the tappet and such supply must be continuous to make up for any loss of oil used which may occur. When hydraulic tappets are initially installed in a new engine, the engine block, tappet guides and cams are designed for hydraulic tappets, including passages for supplying oil to the tappets from the engine lubricating oil supply.

In the present invention and, as a follow up of my earlier invention, which has resulted in Patent No. 2,468,332, granted April 26, 1949, a novel tappet structure is produced, the object and purpose of which is to permit the replacement of the usual mechanical tappets by hydraulic tappets, without the necessity of, at the same time, replacing the tappet guides previously used with others which have the necessary passages and connections for obtaining oil from the engine. All that need be done is to remove the mechanical tappets and install the tappets of the present invention in their place. My earlier patent referred to is directed to novel structure so that the hydraulic tappet may be used in the place of the mechanical tappet previously used without change, either by replacement or by regrinding, of the cam shafts of the engine which operate the tappets.

The present invention completes the economical installation and use of hydraulic tappets in place of previous mechanical tappets, by an elimination of the necessity of replacing the old tappet guide by a new one having oil conducting passages therethrough. Thus the sole expense now with my new invention and that shown in my prior patent is in the hydraulic tappets themselves, eliminating the previous much heavier expense of reconditioning the cams or supplying new cams by my invention shown in the above identified patent; or replacing the previous tappet guides for mechanical tappets by special tappet guides for hydraulic tappets, which, with the use of my present invention, is no longer required. However, the invention while very useful in the situation mentioned, is usable generally in connection with hydraulic tappets and is not to be restricted solely to replacing mechanical with hydraulic tappets.

An understanding of the invention may be had from the following description,.,tal en in connection with the accompanying drawing, in which,

Figs. 1 and 2 are vertical sections through hydraulic tappets made in accordance with the present invention, Fig. 1 showing the tappet on its up-stroke or upward movement as being lifted by a cam, and the other showing the tappet on its down-stroke as the cam rotation permits its downward movement under the pressure of the valve spring, and

Figs. 3 and 4 are similar views of another form of hydraulic tappet having my invention.

Like reference characters refer to like parts in the different figures of the drawing.

The tappet guide l, either an integral part of an engine block or securely connected therewith so as to be in effect integral therewith, remains as it always has been with vertical passages for the reception of the cylindrical tappet bodies 2 therein which are raised and lowered by cam shaft rotation. Said tappet bodies 2 are hollow, each havinga closed lower end 3, the under side of which is hardened, against which the actuating cam 4, also hardened, on a driven cam shaft 5 engages. The tappet is moved upwardly by the cam until the highest point of the cam passes the tappet and recedes from the under side of the bottom 3. The tappet is thus reciprocated in successive up and down movements during engine operation.

The hollow body 2, between its ends, has a transverse partition 6 across it between which and the lower end or bottom 3 of the cam is an oil chamber 1. An outlet opening 8 through the partition 6 permits passage or" oil under working conditions above the partition 6 and underneath a piston 9 mounted within the upper portion of the body 2. Such piston 9 consists of a relatively heavy crosspiece with cylindrical walls which extend both above and below the cross piece, extending farther below than above as shown.

A relatively heavy compression spring id is located between the under side of the crosspiece of the piston and the upper side of the partition 6; The upper end of the passage 8 is covered by a light thin metal disk valve I! which is acted upon at its upper side by a light strength spring within a cage I2, which is of a generally inverted cup form having outwardly extending flanges at its lower end which are pressed against the partition 6 by the spring It, the cage having an opening in its upper side for oil passage. Above the crosspiece t of the piston the lower end of the engine valve stem IS, the valve of which is raised and lowered by the tappet movements, rests upon a disk N1 of fiat spring metal which is concave on its under side and convex on its tical with one form of the invention disclosed in my prior Patent No. 2,468,332. With oil supplied to the chamber I, in any manner that it may be supplied in accordance with old practice, the necessity of replacing or reconditioning the cams 4 when mechanical tappets are replaced in an engine by hydraulic tappets is done away with. The structure described is, however, but one form of hydraulic tappets to which my invention is applicable, as the about to be described structure may be used with many and various types and forms of hydraulic tappets for insuring that oil will be supplied to the tappets in required and necessary amounts.

In the present invention, the tappet body 2 around its intermediate portion is formed with a ring groove l5 continuously around it. From the bottom inner portions of such groove passages it lead through the walls of the tappet body into the chamber 1. A split piston ring I? is installed in the groove l5. The axial dimension of the ring it, that is, its vertical dimension, is less than the axial or vertical dimension of the groove H5, in practice, amounting to approximately ,4,1, of an inch though this may be varied to some extent. The space between the upper or lower sides of the ring and the adjacent upper or lower sides of the groove being enlarged in the drawing. An air vent passage I8 is shown as leading from the upper end of chamber I to the upper portion of groove I5.

The interior diameter of the ring preferably is such that, at its inner curved side, when installed in the ring groove [5 it will be in close proximity to the bottom of the groove.

In Figs. 3 and 4, the same invention is shown in a specifically different form of hydraulic tappet. The tappet body 2 having the closed lower end 3 to bear upon the actuating cam 4 has a cylindrical opening of the same diameter extending from its upper end to the bottom 3. A hollow piston l9, open at its upper end and closed at its lower end, except for an oilpassage therethrough, is supplied with a spring underneath it which rests upon the bottom 3 of the body. It, as a compression spring, tends to move the piston upwardly. The oil passage opening in the lower end or" the piston is is provided with a ball valve 2! at its lower end which is retained in place but permitted a limited amount of up and down movement by a sheet metal cage 22 which has oil passing openings in it below the valve. The piston I9 is interiorly bored from its upper end downwardly to the oil passage with which the ball valve 2! is associated, so that when closed at its upper end, an oil chamber 23 is provided which is supplied with oil through passages I 6 from the groove 55 for the ring I! around the body 2, oil being carried to a shallow and relatively wide annular groove 24 around the piston, from which radial passages 25 to the chamber 23 are made through the walls of the piston. It is to be understood that the ring groove l5 and the ring it therein duplicates the groove [5 and the ring ii in the first described structure, and that the passages [6 in the first described structure leading to the oil chamber 1 is provided for any equivalent manner by the passages I6, groove 2d and passages 25 to supply oil to the chamber 23 in the structure shown in Figs. 3 and 4.

In the upper end of the piston I9 a closure member or plug 26 is inserted which has a sumciently loose fit that it has a limited movement vertically in the piston. From the plug or closure 26 an annular flange 26a extends substantially to the inner walls to the tappet body 2, the flange being over the upper end of the piston 19. Between such flange and the upper end of the piston a yielding corrugated, split spring member or ring 21 is positioned and held. It, like the spring disk 14 in the first described structure, when free tends to lift the closure plug 26 a limited distance the same as the disk l4 tends to separate the lower end of the valve stem [3 a limited distance from the piston 9 in the first described structure. The lower end of the valve stem I3 in the structure shown in Figs. 3 and 4 bears against the hardened upper end of the closure plug 26.

Because of the greater axial dimension of the groove I5 over that of the ring I! in both of the described forms of structure in the up and down reciprocating movement of the tappet the ring, through inertia, will travel from one side of the groove to the other. On the upward movement of the tappet the ring moves downwardly until stopped against the lower side of the groove, as in Figs. 1 and 3, and on the downward movement of the tappet the rin will move relative to the tappet upwardly until stopped by coming against the upper side of the groove [5. On such downward movement, Figs. 2 and 4, the space between the lower side of the ring and the lower side of the ring groove is filled with oil collected from the walls of the tappet guide thereby filling such space. On the upward stroke the relative downward movement of the ring I? forces oil through the passages I6 into the chambers 1 or 23 to keep them filled.

It is to be understood that in the normal splash system of lubricating the crank and cam shafts of internal combustion engines, oil is always present to lubricate the tappets between their outer surfaces and the surfaces of the guides in which they move. Also oil which may escape upwardly between the pistons 9 and I8 and the Walls of the tappet bodies will provide an ample supply of oil to lubricate the tappets in their reciprocating movements. The valve structure within the tappets and the springs id and 20 acting upon the pistons 9 and i9 insure that the plate M or plug 26 will remain in contact with the lower end of the valve stem l3 and that the tappet be properly adjusted at all times. The strength of the valve springs is such that an over exces of oil from the chamber 1 into the space above the partition 5 or from the chamber 23 past valve 2| and below the pistons does not occur but if there is an insufficiency of oil in the chambers l' or 23, oil will be forced through the passages IS into said chambers to maintain them filled with oil at all times.

The novel tappet structures described, while not strictly hydraulic tappets of the self-contained type, have all of the advantages of the self-contained hydraulic tappet with none of the disadvantages. It eliminates the necessity of special tappet guides with oil supplying passages therein, therefore, inany replacement of mechanical tappets in engines by the hydraulic tappets of my invention, the entire expense is the cost of the hydraulic tappets with such labor cost as is required to remove the mechanical tappets and replace them with hydraulic tappets.

The invention described in the two forms of structure is very useful, particularly in connection with the replacement of mechanical tappets by hydraulic tappets in engines which have been designed for and'built to use mechanical tappets, in conjunction with the invention shown in my prior patent referred to above. However, the

invention is also of utility and value with substantially any form of hydraulic tappet insofar as the oil supply for the tappet and the manner in which it is replenished and maintained is concerned, there being an elimination of the heretofore required passages from the oil supply of the engine to the tappets to supply the oil as the hydraulic liquid is used.

The invention is very useful and practical in materially reducing costs in all hydraulic tappet installations, and particularly in the replacement of the mechanical tappets of engines by hydraulic tappets. The invention is defined in the appended claims and is to be considered comprehensive of all forms of structue coming within their scope, whether or not tappets having the equivalent of the spring disk or plate M or the corrugated plug 26 and spring ring 21 are used, the invention not being necessarily restricted solely to the replacement of mechanical tappets by hydraulic tappets, done by a mere insertion of the hydraulic tappet where a mechanical tappet has been previously used.

I claim:

1. A hydraulic tappet having a hollow body closed at its lower end and an oil supply chamber in the lower part of said body, and a piston ring mounted on and around said body, said body having a horizontal groove of dimensions to receive said ring, and permit axial movement of the ring relative to said body, and having an oil conducting passage between the lower inner portion of the groove and said chamber.

2. A tappet as defined in claim 1, in which the inner diameter of said piston ring is a close approximation to but slightly larger than the diameter of the bottom of the ring groove which receives it.

3. A hydraulic tappet as defined in claim 1, in which the dimension of said groove in the direction of the length of the tappet body is greater than the like dimension of the piston ring, whereby the ring moves back and forth between opposite sides of the ring groove as the tappet is reciprocated in operation.

4. In a hydraulic tappet, a tappet body having an oil receiving chamber therein, a piston ring located around the body, said body having a ring groove to receive the ring, the width of said groove being greater than the axial dimension of the ring and the inner diameter of the ring approximating but being slightly larger than the diameter of the bottom of the groove, said body having an oil conducting passage between said groove and chamber for the passage of oil to said chamber, said passage when the ring is at one side of the groove being in communication with space between said piston ring and the opposite side of the ring groove, and said passage being closed when said ring is against said opposite side of the groove.

CHARLES E. JOHNSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,366,080 Wingate Dec. 26, 1944 2,396,018 Mis Mar. 5, 1946

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