US2599886A - Hydraulic tappet - Google Patents

Description

June l0,' 1 952 P. F. BERGMANN HYDRAULIC TAPPET Filed March 10, 1947 "FIG 5.

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ATTORNEYS Patented June 10, 1952 UNITED PATENT OFFICE H DR U A P T Paul rgm nn, Mu n- Hei hts Mich". a "signor' to Johnson Products, -Inc,, 'Muskegon Heights, Mish a corporation of' Michigan n u ati n inar h 10. ,,iSeria NQ-'- .3 9

2 Claims (Cl. 123-30) -'Ih. .,pre.se ,t, invention relates to tanpets of the hydraulic ynera d'i c ncerned with a novel tappetstru' ture y e peditiously and e o om ea ly p ioduee anc 'assemb d, in which any entr'appedair in tl e liquid used is released and l l l natedv r m the ta net. In general. a p f e ed, economical, very effective and practical ta pet st ct reis pro ced- An nde stan in 9 h ve i n atta n h en s siaie m b v oad om th l w n description of a preferred embodiment of my inwe i e taken in nne t qli th he ac omnanv ,1 win in which.

{Fig'. 1 is eamen vertical section-through the novel tapp'et' structure, showing the piston in lowermost position,

Fig.2 is a'similar fragmentary section of-the upper portionof the tappet, with piston thereof mm inapproximately operating position, Figs. :3 and 4 are, respectively, horizontal sections on 'the planes of lines 33 and 4-4 of Fig. 1,-1ooking in the directions'indicated bylthe arrows; and

Fig.5 is an enlarged perspective view of the sheet metal element which serves as a cage or housing for the disc valve and which has a presst ht connection with the lowerrend of the hydraulically operated piston of the tappet.

. Like reference characters refer to like parts'in the difierentviews of the drawing.

In the disclosure .shown in the drawing, the body I of the tappet, ofla substantially cylindrical form has a head 2 at its lower end, the disclosure being in connection with tappets-of the mushroom .type, in which ingeneral the crossseetional area of the tappet bodies is less than tappets of the barrel type. My-invention while particularly applicable. tomushroom type tappets, is not to be restricted thereto, as it is useful in connection with all of the standard tappet types having varying diameters or cross-sectional areas.

'llhe body I has walls surrounding a cylindrical longitudinal opening" therein, which is closed at its lower end by the head 2 and is open at its F lmer endj Said opening is ofa larger diameter ppe o tio o the b d t an n the l i ef ei lenihere e f n annu ar hor zontal shoulder 8 be en e two eg ion o s d ma istr tes mid a in th en th of ;2 the body. Therwallof the body ,I -.a short dis.- tancebe ow sa d shou d r 3 ha esa thehydraulieliquid used, which in internal v combll$ q n ne is h lv rica ine 011.0 5 the e sine w ch u de -.th rr ssu or t pump wi pass throughthe passage .4 an into the lower end portion of the tap 'et body to fill a chamber 5 with oil, saidchamb'er always being fully supr plied with oil under pressure .when the [engine is p ll l ntothe upper end of the .tappet body I a cylindel' 13 inserted. Said cylinder has walls 6. which at their upper ends arethickened to provide a head .Iflwhich rests" upon the upperend of the wallsof the body]. The cylinder 6 at its lower end ortion is reduced in d me er, provid ng a lower cylindrical extension 8 which at its lower end .is wholl closed b a n rs ott m a... The wall .6 just below head I is reduced in diameter fora short :distance iorming an undercut that provides spaceior vair to collect in, that might-becarried inthe oil. The exterior diam-1 ter vof the p is app bly s t an the interior diameter of the chamber 5 as shown, and the shoulder between the upper and lower walls fie d 3 Qt t cylinder i at a hor dis an above the previously described annular shoulder ,3 .of the tappet body, when upon insertion. ofthe cylinder into the body it is stopped by head .I comingagainst the upper end of thetappet body. 'Ihe wallof the cylinder a short distancebelow the head, let one side has a passage IO there: through, Atsuch side of the cylinder wherethe passage I0 is lpcated. a portion of the wall of the cylinder is removed in a shallow segment, leaving a vertical passage II between the body I andsaid cylinder (Figs. 3 and 4) which connects said passage I0 with the oil supply chamber 5. The axialopening in the cylinder is reduced in diameter at approximately two-thirds of its len th downward in the cylinder providing an annular shoulder 12, and in the lowermostportiqn of the cylinderimmediately above the bote tom 9 a .further reduction in diameter is made so that a short length of the lowermost portion or the axial openingin the oy ind rat L3, isdf a smal er am er th an o her a t of s ch openin 1 Ii -Stan A ismse te m -the Qillillfilfil 5 t upper eesl, which, w ieniaiisil weime osition bears against the shoulder l2. The piston I4 is axially bored from its lower end upwardly, approaching but stopping short of the upper end of the piston, as at I5. Around the piston substantially midway between its ends an annular groove [6 is provided, and radial passages I! connect the groove I6 with the interior axial passage IS. The lower end of the piston is also machined to provide an annular groove l8, in the lower end face of the piston, with annular inner and outer ribs, one inside the groove around the opening [5 and the other outside the groove [8 as shown.

A strong coiled spring 19 is received at its lower end within the reduced diameter portion l3 of the cylindrical opening in the cylinder 6, having a tight fit therein, and extends upwardly toward but short of the inner or lower end of the piston M. A disk 20 of flat metal is located across the lower end of the axial opening I5. A sheet metal cage has an upper cylindrical wall 2| with a partial bottom from which a smaller diameter cylindrical wall 22 extends downwardly 1 concentric with the wall 2|, with an opening in the bottom of the cage. A light coiled spring 23 is located within the cage between said bottom and the disk valve 20, being of suflicient strength to hold the valve 20 in its upper closed position when the pressure forces on opposite sides of the valve are equal, but the valve being readily moved downward against said spring upon the pressure forces of the liquid in the passage [5 being but slightly greater than those of the liquid below said valve.

Near the upper end of the axial passa e I5 in the piston a radial passage 24 extends outwardly, its outer end coming to the thickened wall of the head 1 of the cylinder described.

It is evident that the oil under pressure of the engine pump filling the chamber 5 will thence pass upwardly in the vertical passage H provided as described, and will go through the passage l into the roove l6 and thence through passages I1 into the axial opening l of the piston M. And such oil will move the valve 20 downwardly, filling the chamber below the piston l4 and within the lower portion of the cylinder walls 8, until there is a balance of pressure on both sides of the valve '20. In the operation, the lower end of the stem of an engine intake or outlet valve, bearing against the upper end of the piston l4 will, upon lifting such engine valve, transmit the force of the valve spring to the piston and thence to the liquid underneath which, being incompressible, the engine valve will be lifted. When on the rotation of the cam shaft such engine valve is returned to closed position, if the upper end of the piston l4 tends to separate from the lower end of 'the engine valve, due to leakage of oil past piston I4 during the opening, the heavy sp l9 will force the piston 14 to continue to bear against the lower end of the stem of the engine valve moving the piston I4 upwardly, and thus create a partial vacuum in the chamber below the piston which will be satisfied by oil coming from the passage I5, past the valve 20, to said chamber. Any slack in the valve is immediately taken up and adjustment maintained between the tappet and the engine valve.

As shown in Fig. 5, the sheet metal cage walls at 2| are vertically slit at spaced distances from each other, so that said walls may be contracted and be received within the outer annular rib at 4 bly of the cage with the piston I4 is not only immediately done by mere pressure, but no machine operations beyond the formation of the cage and the cutting of the groove at I8 are required. Substantially all parts of the tappet structure except the springs, the described cage and the disk valve 20, are performed on an automatic screw machine or other automatic lathe. The springs are purchased from manufacturers of the springs who produce them very economically in large quantities, and the disk valve 20 and the sheet metal cage are produced by rapid punch press operation, leaving only the drilling of the radial and lateral passages in the several parts where needed.

It is further evident that if there is any air in the body of oil chamber 5, it will tend to rise and pass upwardly through the passage provided at H, and thence into the axial opening l5 of the piston, and further rise to the upper portion of said passage and escape through the radial passage 24, and thence between the upper end portion of the piston I 5 and the head portion 1 of the cylinder described; or it will go up past hole It to the annular groove under head 7, and gradually out between the top of the tap-pet body and the shoulder at the bottom of head 1. At the completion of eachrotation of the cam there is an opportunity for the air to escape between these surfaces.

The tappet structure disclosed is one very readily and economically produced in large quantities and very easily assembled. The cylinder inserted within the walls of the tappet body is inserted therein by dropping it in till the head 1 of the cylinder interposes a stop against further movement. The spring I9 is merely dropped into place, the assembly of the valve 28, the spring 23 and its enclosing cage is made at the inner or lower end of the piston and the piston then merely inserted until the reduced portion 22 of the cage enters the upper end of the spring I9. A-very practical, durable and economically constructed tappet, and one which operates very effectively, is produced.

The invention is defined in the appended claims and is to be considered comprehensive of all forms of structure coming Within their scope.

. I claim:

1. A tappet comprising, an elongated hollow cylindrical body closed at one end and having an opening through a side thereof, a cylinder 1 extending into the open upper end of the body there being a vertical passage between said cyl inder and the adjacent wall of the tappet body providing communication between said last mentioned opening and said chamber, said cylinder at its upper end portion having a head resting upon the upper end of the body and stopping the cylinder within the body at a predetermined position, a piston in the upper end of said cylinder extending downwardly therein, said cylinder and piston having inter-engaging means limiting the entrance of the piston into the cylinder to a predetermined lower position, said piston having an axial opening therein from its lower end extending toward but terminating short of the upper end of the piston, and said piston having a radial communicating passage joining with said axial opening and said piston having an annular groove around it in communication with the passage through the wall in the cylinder and radial passage in the piston, a valve across the lower end of the axial opening in the piston, a cage connected with said piston at its lower end and within which the valve is located, said cage having an opening at its lower side, a light strength spring means within said cage normally holding said valve in an upper closing position, and a heavier spring between said cage and the closed bottom of the cylinder.

2. A structure as defined in claim 1, said piston having a radial passage from a side thereof extending inwardly to and communicating with the axial opening in the piston, said radial passage connecting with the upper end portion of said axial opening.

PAUL F. BERGMANN.

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

UNITED STATES PATENTS

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