US2438631A - Hydraulic tappet - Google Patents

Description

March 30, 1948. BERGMANN 2,438,631

HYDRAULIC TAPPET Filed June 24, 1946.

4. g g/ T mi 19W? j 6; H

l4 7 'Y'\e. 3

' 5 -Y|GA PAUL E baaemmu imam ATTORNEYS Patented Mar. 30, 1948 UNITED STATES PATENT OFFICE HYDRAULIC TAPPET Paul F. Bergmann, Muskegon, Mich., assignor to Johnson Products, Inc., Muskegon Heights, Mich., a corporation of Michigan Application June 24, 1946, Serial No. 678,744

6 Claims. (01. 12390) The present invention relates to and is concerned with self-adjusting tappets of hydraulic character. It is a primary object and purpose of the present invention to provide a practical, relatively simple hydraulic tappet in which the hydraulic liquid used, generally oil, is contained within the tappet, does not drain therefrom to be resupplied from the lubricating oil of the engine with which the tappet is used, but somewhat in analogy to certain types of shock absorbers, the oil is maintained within the tappet; and if after a long use, the oil should be diminished in quantity, the tappet chambers which hold the oil, are refilled.

Hydraulic tappets wherein the oil is continuously supplied from the lubricating system of the engine, have been developed to a considerable degree of perfection. In their installation on an engine, it is necessary to supply suitable guides for the moving tappets having oil conducting passages which lead to the tappets, to supply them With oil from the engine lubricating system under pressure; and, it is necessary to use whatever oil may be in the engine and in whatever condition such oil is.

One feature of the present invention and a very desirable object to be secured thereby, is that, where the oil is self-contained in the tappet, a proper grade of oil of desired characteristics as to viscosity and fluidity under changes of temperature may be selected and used without reference to the lubricating oil used in the engine. The car owner may use a poor grade of oil without affecting the hydraulic tappets. Furthermore, with the present invention, the expensive special provision of passages for oil from the engine to the tappets and a connection with the oil pressure system of the engine is elimi nated.

An understanding of the invention may be had from the following description taken in connection with the accompanying drawings, in which,

Fig. 1 is a vertical section through the tappet of my invention, with the parts positioned as they will be when the tappet is supplied with oil.

Fig. 2 is a similar view of the completely assembled tappet, with the parts in the position that they take when the tappet is out of an engine and not installed therein.

Fig. 3 is a similar section showing the tappet in a vertical guide in the engine block and located between its actuating cam and the lower end of a valve stem, the parts being in normal position which they occupy in service, and

Fig. 4 is a horizontal section substantially on 2 the plane of line 4--4 of Fig. 2 looking in the direction indicated.

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

The tappet body I of cylindrical form has a closed lower end 2, the under side of which is adapted to bear upon a cam 3 of an engine cam shaft. Said cylindrical body of the tappet is mounted for reciprocation in a cylindrical passage therefor, made in the engine block or in a member permanently connected with the engine block to be the same in effect as though integral therewith.

The body I of the tappet is substantially hollow having vertical cylindrical walls. Substantially midway between its upper end lower ends a horizontal partition 5 is cast with the remainder of'the body. The body'below the partition 5 is cored out to reduce weight and save material. Above the partition 5 a distance which, as shown, equal to approximately one-third of the distance between said partition and the upper end of the tappet body, an annular horizontal shoulder 6 is made between an upper larger diameter interior portion of the tappet body and a lower lesser diameter interior portion.

In the upper larger diameter interior portion of the tappet body a piston is movably mounted having vertical walls I and a horizontal bottom or lower end 8, at the central portion of which a vertical opening or passage 9 is made through it. A thin plate valve Ill is normally held in an upper position to close the passage 9 at its lower end by a light compression spring II, which is supported at its lower end by the bottom of and is located within a surrounding cage of sheet metal l2. A heavy coiled compression spring l3 rests at its lower end on the partition 5 and at its upper end, presses the upper annular flange of the cage 12 against the lower side of the piston described. The piston walls 1 between their upper and lower ends have radial openings [4 therethrough. There is also an annular groove around the piston above said openings in which a sealing member or packing l5 is located for the purpose of preventing upward passage of oil thereabove between the pistonwalls 1 and the walls of the body I.

Said piston, as shown, is substantially of cup shape. Its upper end is closed by a horizontal top l6 welded or otherwise permanently secured and seated in place. At the central portion of the top It a housing I! extends upwardly closed at its upper end and against which the lower end of the stem [8 of an engine valve engages. The

upwardly extending housing I! is interiorly recessed to provide a cylindrical recess as shown, within which a plunger IQ, of a form similar to a cup leather, is located which is normally moved in a downward direction by a coiled spring 20 located above it, its upper end resting against the lower side of the top of the housing IT.

The horizontal top member I6 has an opening therethrough, interiorly threaded, which may be closed by a screw plug 2|, said plug being removable when desired. Adjacent the upper end of the tappet body I and at its inner side, an annular groove is made within which a split spring ring 22 is seated.

The construction as thus described provides an oil chamber '23 above the partition and below the bottom 8 of the piston, and also a second 'oil receiving chamber 24 within the piston and below the plunger IS. The chamber above the plunger 3 I9 contains air which is compressible. The tappet may be supplied with oil by removing the screw plug at 2| and inserting the spout 2501 an oil can or equivalentthrough said opening, thereby filling both chambers 23 and 24 with oil. 'The spring H is of a sufliciently light character that it does littlemore than balancethe weight of the valve it] so that the oil can be readily passed by the valve II! to fill the lower chamber 23. During oil filling a a replacement of oil, the split ring22 is removed so'that the piston wall 1 will extend a short distance above the upper end of the tappet, being lifted to such position by 4 economical, from both utility and production standpoints. The sealing member at I5 keeps the oil from escaping to above'the piston. There is a closed circuit for oil movement which is governed and controlled .by the springs l3 and 20, and the compressed air above the plunger i9, serving to maintainthe tappet and the lower endof the valve stem in contact engagement at all times. The tappet is automaticall self-adjustable and tappet noises in engine operation are eliminated.

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

spring l3. The plunger 19 will be at its lowermost positionwith the compression spring 20 fully extended. After the oil has been fully supplied for 'a tappetfthe screw plug 2i is replaced and the Piston forced downwardly so that the retaining ring 22 may be-put back in place, as in Fig. 2. Oil from the lower chamber 23 during such operation will pass between the outer sides of the walls 1 of the piston and the inner sides of the surrounding walliofthe body and through the openings M to the; chamber 24, withan upwardmoving of the plunger i9 and a compression of the spring 20, and the air above valve 19.

In operation, as indicated in Fig; 3, the pistoni will be acted upon from below spring F3 to press theupper end of the housing I! against the lower end of the valve stem it, said piston, in normal operating position, being located a short distance below the ring 22. As a consequence thereof more of the oil from the chamber 23 is transferred ill t0 the chamber 24 with an accompanying further 7 upward movement of the plunger [9. The air within the chamber above the plunger i9 under compression transmits an equal pressure through the plunger ['9 to the oil in the chamber 24, so that if the pressure in the chamber 23 becomes lower than the pressure in the chamber 24, oil is forced past the valve at l'il into said chamber 23 until the pressures are equal. The oil, therefore, has a-pathof circulation, for example, from the chamber 23 upwardly around the walls of the cylinder 1, through the radial openings i4 to the chamber 23 and therefrom through the passage 9 past the valve Hi to the lower chamber 2-3. As a-result,:the upper end of the housing IT and the lower end of the valve stems i 8 are maintained in contact at all times but with no danger that an engine valve may be lifted above its valve seat, except at such times as it is wanted, for example, in opening for'the intake 'of'the explosive fuel mixture into an engine cylinder past an intake valve or the'outward passage or gasses of combustion 'fljom an engine cylinder past an exhaust valve.

I claim: '1. In a tappet'structure, a cylindrical tappet body having a cylinder recess at its outer end thereof, a chambered piston mounted for movement therein having a wall and a closed inner end, a closure for the outer end of said piston providing a chamber in the piston, the wall of said piston having a pas'sage therethrough'communicating with said chamber and said closed inner end of saidpiston having an opening there-1 through, a spring actuated valve closing said opening, spring means normally tending to move the piston in an outward direction, said closure at the outer end of the piston having an out wardly extending housing with an inner recess therein communicating with said chamber within the piston, a movable plunger located in the said recess forming a partition between said chamber within the piston and the recess space within said housing and a spring normally tending to force said plunger in an inward direction. 2. A construction as defined 'inclaim 1, and sealing mea'ns between the piston wall and'the tappet body located around the piston outwardly of the passage through the wall thereof. 7 I

3. A construction as defined in claim 1, and removable means for closing said chamber within the piston, said means being removable for the passage of a liquid thereinto, and the space within said housing being sealed off by the plunger from said liquid, said space outwardly of the valve containing air. r

4. A self contained hydraulic tappet structure comprising a cylindrical body having a, downwardly extending recess in its upper end, a piston mounted within the upper portion of the body, said piston having an oil receiving chamber therewithin and having a Vertically extendplunger within and extending across said recess to'separate the chambered portion of the piston into two parts whereby the upper recess may contain air and the lower chamber liquid, said piston at its lower side having an opening therethrough, a valve'normally spring closed at the lower side of said opening, a relatively heavy compression spring between thelower side of the'piston and the bottom of the cylindrical recess in'which it is located, said piston in the sides thereof having passages extending there! through communicating with the, chamber therein, and spring means normally forcing the plunger in the recess in a downward direction.

5, A tappet construction comprising a tappet body having a cylindrical recess in its upper portion, a chambered piston therewithin having a valve closed passage from the chamber within the piston'to said cylindrical recess within the 7 body below the piston, said piston having restricted liquid passing means for the circulation of the liquid from below the piston to the chamher therewithin, movable means for dividing the chambered piston into two parts one over the other, the lower of said chambered portions being adapted to contain liquid, and the upper portion to contain air, and yielding means normally tending to enlarge the air portion of the chamber and lessen the capacity of the liquid containing portion thereof acting upon said movable dividing means.

6. In a hydraulic valve tappet, a tappet body, a member located in the upper portion thereof against the upper end of which the lower end of the engine valve stem is adapted to bear, said member having therewithin a liquid containing chamber and an air containing chamber, movable means separating said air and liquid containing chambers, resilient means to move said movable means in a direction tending to enlarge the air chamber and decrease the liquid chamber,

6 means for providing a circulation between said oil containing chamber of said movable member to below said movable member and therearound back to the liquid chamber thereof, and resil- 5 ient means normally tending to move said movable member in an upward direction.

PAUL F. BERGMANN.

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

UNITED STATES PATENTS

Images