US2246330A - Hydraulic tappet construction - Google Patents

Description

June 17, 1941. QyQQRI-HES 2,246,330

HYDRAULIC TAPPET conswnucnou Filed March 14, 1940 lNVE R CHE-L. OR'H/ES ATTORNEY Patented June 17, 1941 HYDRAULIC TAPPET CONSTRUCTION Carl Voorhies, Detroit, Mich., asslgnor to Eaton Manufacturing Company, Cleveland, Ohio, a

corporation Ohio Application March 14, 1940, Serial No. 323,869

4 Claims.

This invention relates generally to automatic compensating tappets ,for operating valves oi! internal combustion engines, and more particularly to the addition of means thereto which improve the operation of hydraulic tappets of such character. The general type or tappet with which my invention is associated is shown in my prior issued Patent No. 2,074,034.

The principal object of the present invention is the provision of filter means in a hydraulic tappet construction around or adjacent the liquid conduit therein; by means of which operating fluid is conducted from the fluid supply reservoir to the compression chamberoi the hydraulic taD- pet in an air-free, clean condition. a I

A further object of the invention is the provision of separate, apertured washer-like filter the tappet embodying this invention, shown positioned between a cam and valve stem.

Fig. 2 is a perspective view of an air filter means removed from the tappet construction shown in Fig. 1.

For a more detailed explanation of the several component parts and actual operation of the type of hydraulic tappet to which this invention is applied reference may be had to my above identified prior patent, Fig. '7, only so much of the operation thereof as is necessary to effect a complete understanding of the improved device is recited herein.

disks which may be positioned on a conduit tor liquids in a hydraulic tappet as above described in amounts of selected number on future or existing tappets now in service without any alterations in construction.

Various problems have been encountered in the application of this device for the automatic com.-

pensation or slack take up in valve gear of in-.

ternal combustion engines, one oi. which is the problem of providing adequate means for relieving and bleeding air or compressible gas from the hydraulic medium carried in the reservoir of the I I tappet, in order that the trapped hydraulictcola umn upon which the plunger rests will be as nearly as possibleincompressible when the plung er is forced against the valve stem. Another has been to provide sufficiently clean hydraulic medium, whichis generally supplied from the sump or the lubricating system or the engine, in view of the serious consequences of even small particles of foreign matter in the hydraulic fluid finding their way into the close fits maintained between the accurately finished and. relatively recipr cable parts of'the hydraulic mechanism. Accor ingly, to this end, the present invention accomplishes among other things the objects of the invention above enumeratedand to. be hereinatter described.

Other objects; features and advantages will become apparent from a study of the drawing and v accompanying description forming a part 01' this specification and more particularly pointed out in the appended claims.

For the purpose of illustrating the genus of the invention a concrete embodiment of the invention is shown in the accompanying drawing, in which a Fig. 1 is a longitudinal cross-sectional view 0! The-numeral I represents the end of the stem of the conventional p ppet valve which is resiliently urged downwardly to its seat in the well known conventional manner (not shown). The numeral 2 indicates a conventional camshaft with the cam 3 mounted thereon. The numeral 4 represents the usual conventional tappet guide sleeve provided in the cylinder block of the engine. The numeral 8 represents a mushroom type tappet of the conventional shape'provided with an enlarged cam contacting head I and an elongated tubular body 8. The body 8 shown is provided with a hollow bore 8 closed at the lower end and which provides a. reservoir for oil which is supplied through the side of the guide 4 by the supply pipe ll connected with the usual lubricating system. The body of the tappet 8 is also provided with a circumferential groove ll into which oil supplied by the pipe l0 flows. An oil inlet aperture V I2 is provided in the tappet body '8' leading thereinto from the groove H to the reservoir 9 into which the oil flows. The bore in the upper part oi. the tappet body 8 is enlarged and an abutment shoulder I3 is thereby provided at the lower end or the enlarged portion of the bore. Inserted in the enlarged portion of the bore is a cylinder sleeve member ll which comprises a cylindrical member having an enlarged bore in its upper end and a separate shouldered tubular extension I! pressed therein at its lower end, which, when the member ll isinserted in the enlarged bore of the tappet body 8, extends below the oil inlet aperture I2 and deep down into the oil reservoir 8 in the lower part of the tappet body.

Positioned in the cylinder sleeve 14 a solid plunger ll, which contacts the valve stem I with its upper end. is reciprocably mounted and adapted to be biased outwardly with respect to the separate cylinder by means of a spring ll. Positioned in the lower end of the cylinder I4 is a ball I! seating against and covering the upper end of the opening through the tubular extension l5. surrounding the ball is a retaining cage member 09, having an aperture 20 in its upper end, and press-fitted into the reduced bore of the cylinder l4 abutting the upper end of the tubular extension 15 to retain it in place and fix the amount of ball travel.

The operation of the device is as follows:

As the cam rotates and the tappet head rides upon the base circle of the cam, the tappet body moves downwardly in its guide under the influence of the spring pressed valve stem l. Normally and in a rigid and non-extensible type of tappet, the pressure of the valve stem against the end of the tappet would cease shortly before the tappet reached the base circle of the cam, thus relieving substantially all the pressure of the valve upon the tappet, In the device disclosed, however, when the pressure of the valve stem ceases, the coil spring ll will urge the plunger i6 outwardly and maintain its contact with the valve stem. This outward movement or the plunger it will reduce the pressure in the space between the end of the plunger l6 and above and within the ball cage member i9 and permit the ball I8 to rise from its seat, under the relatively greater pressure in the oil reservoir 9, and permit oil in the reservoir to flow past the ball and fill the space between the end of the plunger i6 and top of the cage member l9. Then as the tappet moves upwardly through rotation of the cam and with the ball in closed position the oil in the chamber in the lower portion of the cylinder M will be trapped, thus providing an incompressible hydraulic column which will maintain the plunger in flrm contact with the valve stem I during the entire stroke of the tappet. The pressure of the plunger l6 against the trapped oil thereunder normally will cause a slight leakage of the oil outward around the sides of the plunger, and the oil-so eliminated will be replaced as the cycle of operation repeats and the pressure of the valve stem upon the plunger is relieved when the tappet rides upon the base circle of the cam and permits the spring I! to force the plunger outwardly thus permitting the ball to rise' from its seat and admit more oil into the space between the end of the plunger l6 and above the ball cage member is, as previously described.

Since the oil supply for the hydraulic valve tappet 6 is generally taken from the lubricating system of the internal combustion engine with which it is associated, it is apparent that care must be taken that only clean hydraulic fluid will be supplied to the relatively close fits maintained between associated movable parts of the hydraulic tappets in order that foreign particles will not interfere with the smooth operation thereof.

Difllculty has also been experienced in preventing air or compressible gas from working into the hydraulic column under the plunger l6 which will compress when pressure is exerted upon the plunger and thereby introduce lost motion, It is essential that the hydraulic column beneath the plunger be as incompressible and rigid as possible in order to permit accurate and dependable adjustment and timing of the valve mechanism. There is inevitably some air and gas entrained in the oil which is pumped into the reservoir 9 inrthe tappet and part of this will troduced air or gas that does not readily separate from the fluid supply and that forms an emulsion with the oil during the rapid reciproca tion and churning of the fluid in the tappet as the engine is running is the part that is necessary to remove in order to secure the proper valve lift with the hydraulic valve tappet, as aforementioned.

In the present invention these didlculties, l. e. of foreign particles and compressible gas in the hydraulic operating fluid, have been solved by providing in the oil reservoir 9 one or more filters 2| which in this instance are washer-like disks with an axial aperture therethrough so as to be positioned on the upper end of the tubular extension 55 and below the oil inlet l2, of the tappet body. The filters 2| are composed of wool felt, or other suitable filtering material, and have an outer periphery of suflicient extent to extend transversely across the full diameter of the annular reservoir Q. With this construction and arrangement of parts assuming the hydraulic fluid entering the tappet body contains some air it must all pass downward transversely through the entire filtering means before it is accessible to the entrance to the lower end of theliquid conduit l5 and the check ball l8. Thus any air rise to the top of the reservoir where it will find its way out to the atmosphere between the walls of the separate cylinder M and the tappet body 8. However, the portion of the inbubbles, foreign particles, or compressible gas will be prevented from passing, so that the liquid which finally enters through the check ball [8 into the hydraulic column under theplunger I6 is practically incompressible.

Formal changes may be made in the specific embodiment of the invention described without departing from the spirit or substance of the invention, the scope of which is commensurate with the following claims.

What I claim is:

1. A hydraulic valve tappet comprising, in combination, a tappet body having a longitudinal bore closed at its lower end and open at the upper end and having an oil passage in its side wall above the closed end, the lower part of said body including a liquid reservoir, a hydraulic compensating mechanism reciprocably received in the open upper end of said bore, a valve controlled passage adjacent one end of said mechanism, conduit means communicating at one end with said passage and at its other end with the interior of the tappet body adjacent said closed end thereof, and one or more oil filtering means disposed around said conduit means between said oil passage in the tappet body wall and the end of said conduit adjacent the closed end of said tappet body.

2. The combination ina hydraulic valve tappet, according to claim 1, in which said oil flltering means comprise preformed annular washerlike disks of wool felt snugly fitted in the bore of said tappet body and said oil conduit extended therethrough.

3. A hydraulic valve tappet comprising, in combination, a tappet bodyhaving a 10L5itl1diI1B-l bore closed at its lower end and adapted to receive a liquid, a hydraulic compensating mechanism including a separate cylinder disposed in said bore, a tubular projection on the lower part of said cylinder and extending into the lower part of the bore in spaced relation to the wall thereof, valve means controlling the passage of fluid through said projection, means for introducing liquid into the lower part of the bore at a point above the lower end of said tubular element, and filtering means disposed around said tubular mean 3 element between the lower end thereof and and mun: mechanism reclproeclaly recelved in liquid inlet. the 'open upper end of said bore, a valve con- 4.'A hydraulic valve tappet comment combination, a tappet body havln: l longitudinal bore cloned at its lower end and open at the upper endlndhavlnaanoflmelnltlaldewall .nbove the closed end, the lower port 0'! Illd body including: llquld :eeervolr. e hydnullc controlled me adjacent one end of said mechanllm, and fllterln: means interposed in said liq- 5 uld recervoir between the oil passage therelnto aid said valve controlled passage.

' CARL VOORHIES;

Images