US2553756A - Self-contained automatic valve tappet - Google Patents

Description

D May 22, 1951 H. H. ENGEMANN SELF-CONTAINED AUTOMATIC VALVE TAPPET Filed Dec. 6, 1946 HERBERT EN EMANN' Patented May 22, 61951 SELF-CONTAINED AUTOMATIC VALVE TAPPET Herbert H. Engemann, Cleveland Heights, Ohio Application December 6, 1946, Serial No. 714,491

-10 Claims. ('01. 123-90) This invention relates to self-contained automatic adjusters for taking up clearance in a linkage assembly without producing an unwanted extension of the assembly.

Specifically, the invention deals with a selfcontained hydraulic valve tappet of the piston and cylinder type which is equipped with a separate shell around the cylinder and has expansible bellows anchored on the ends thereof.

The valve tappets of this invention are complete in themselves and need no communication with reservoirs for hydraulic operating fluid or the like.

According to the invention, opposed interconnected fluid-filled expansible and contractible chambers feed a piston chamber in a cylinder with working fluid and receive working fluid from the piston chamber. The piston is bottomed on fluid trapped in the chamber during the Valveopening cycle. A check valve on the cylinder traps the fluid in the piston chamber. Some leakage occurs from the piston chamber into one of the expansible chambers during the valveopening cycle, and a very slight clearance condition is thereby obtained in the valve linkage during the valve-opening cycle. ,This clearance may be increased or decreased by wear, expansion, or contraction, but is immediately reclaimed after the valve-closing cycle, wherein working fluid from the expansible and contractible chambers is again admitted into the piston chamber through the check valve for acting on the piston to cause it to assume a no-clearance position.

A feature of the invention resides in the use of expansible and contractible chamber-defining members secured on opposite ends of a cylinder containing shell for housing the working fluid of a piston-actuated tappet without ever subjecting these chambers to force-transmitting loads. Since these chambers are conveniently defined by metal bellows, the bellows metal is soldered or brazed to the shell without distorting or affecting metallurgical properties, such as hardness, of the cylinder or the piston.

Another feature of the invention resides in the formation of a passage connecting the bellows chambers by merely creating a localized gap between the shell and cylinder. This gap is conveniently produced by grinding or machining a flat band area along the length of the outer face of the cylinder.

Still another feature of the invention resides in the provision of a check valve on the cylinder instead of on the piston of a self-contained piston and cylinder type tappet to thereby eliminate heretofore required valve-closing springs.

A further feature of the invention resides in the provision of a tappet assembly that can'be easily completely filled with working fluid to purge out heretofore-encountered air bubbles which, being compressible, cause malfunctioning of the tappet. The elimination of air from the tappet renders it useful in any position.

An object of the invention is to provide a selfcontained piston and cylinder type automatic extensible and contractible device for controlling clearance conditions in a linkage assembly, which device has a separate bellows-carrying shell surrounding the cylinder thereof.

A further object of the invention is to provide a self-contained automatic hydraulic valve tappet having expansible and contractible working fluid chambers which are never subjected .toforce-transmitting loads and are connected with each other through a gap between two nested members.

A still further object of the invention is to provide a self -contained cylinder and piston type automatic valve tappet with opposed interconnected liquid-filled spring bellows for feeding working fluid through a cylinder-mounted check valve to a piston chamber and for receiving working fluid leaking from the piston chamber thereby causing the piston to contract the tappet when loaded during a valve-operating cycle, and to extend when unloaded during a valve operating cycle.

Another object of the invention is to provide a self-contained hydraulic valve tappet with a piston acted on by liquid trapped with a springless valve during the valve-opening cycle and receiving additional liquid thereagainst after the valve-closing cycle for replenishing oil leaking past the piston during the valve-opening cycle, with an amount just sufficient to cause ex tension of the tappet to a no-clearance condition in the valve linkage.

Another object of the invention is to provide a piston and cylinder type bellows-equipped valve tappet with a floating piston free from anchoring connections with a bellows.

A further object of the invention is to provide a self-contained hydraulic valve tappet with opposed liquid-filled intercommunicating bellows chambers on the ends of a separate shell, a piston chamber connected to one of said bellows chambers through a check valve-controlled passage, and a piston slidable freely in the chamber to allow leak-down of fluid from the piston chamber into the other bellows chamber.

Other and further objects of this invention will be apparent to those skilled in the art from the following detailed description of the annexed sheet of drawings which show a preferred embodiment of the invention.

On the drawings:

Figure l is an enlarged axial cross-sectional view, with parts inelevation, of a self-contained hydraulic valve tappet according to this invention in its free expanded condition.

Figure 2 is a view similar to Figure 1, but illustrating the tappet in its working condition in a valve train.

Figure 3 is a transverse cross sectional view taken alon the line IIIIJI of Figure 1.

Figure 4 is a framentary cross-sectional view of an alternate end cap arrangement illustrating a filling of the tappet with fluid.

Figure 5 is a view similar to Figure 4, but showing the filling tube in sealed condition.

As shown on the drawings:

In Figures 1 and 2 the reference numeral I I] designates generally a self-contained automatic valve tappet according to this invention. The tappet I includes a hollow tappet body II .pro-

viding a chamber I2. The body II has a closed bottom IIa, a cylindrical side wall Ilb, a thickened rim top portion lie, and a top shoulder Md. The thickened port-ion IIIc provides a reduced-diameter bore I2a giving access to the chamber I2. A shell I3 is partially disposed in the chamber I2 and has a cylindrical side wall I3a snugly fitting the bore I2a together with an out-turned flange I3b bottomed on the shoulder Md. The shell I3 is hollow with open ends, and has an internal shoulder I3c intermediate said open ends. A first rim bead I3d isprovided at the upper end of the shell above the flange I3b and has anchored thereon one end of a first springmetal bellows 14. The other end of the shell has a second rim bead I3e having anchored thereon one end of a second spring-metal bellows I5. To insure leak-proof joints between the shell and bellows, the bellows are soldered, brazed, or welded to the ends of the shell. The bellows I4 is outside of the body I I, while the bellows I5 is disposed entirely within the chamber I2 of the body II, but in freely spaced'relation from any of the walls of the body.

A cylinder I6 is seated in the shell I3 and has a shoulder I601, bottomed on the shoulder I30 of the shell. The cylinder I5 has a cylindrical bore I6b extending from the open top thereof to a slightly enlarged chamber I60. A piston I1 is slidable in the bore I61) and has its end face projecting into the chamber I66. The piston I! has an integral rod portion Ila projecting above the cylinder I6, and terminating in a head I'Ib having a rounded top surface [10. The top end face of the cylinder I6 has a groove I6d therein receiving the bottom end coil of a spring I8. This spring I8 has the other end coil thereof bottomed on a shoulder provided under the head I lb of the piston,so that the spring is effective to urge the piston outwardly of the cylinder I6. An end cap I9 overlies the piston head I11) and is adapted to rock on the surface I'Ic thereof. This cap I9 has a bead rim I9a around the bottom thereof receiving the top end of the bellows I! in sealed engagement therewith. The cap I9 has ;a fragmental spherical recess I921 in its top face adapted to receive therounded lower end of a push rod P (Figure 2) in a valve train.

4 shell I3. This chamber 20 receives the piston rod Ho and the spring I8 therein.

The bellows I5 in the chamber I2 of the body II is closed by an end cap 2| having an internally threaded boss portion 2Ia receiving a threaded closure plug 22. The bellows I5 thus encloses a chamber 23 on the lower end of the shell I3 withinthe chamber I2 of the body II.

This chamber 23 is in'communication with and receives a part of the cylinder I6.

The bellows chambers 20 and 23 are joined by a, passageway 24. This passageway 24 is formed between the shell I3 and cylinder I6 by a flat band area "is on the outer cylindrical wall of the cylinder I6 as best shown in Figure 3.

The bottom of the piston chamber I in the cylinder I6 has a well IS in the central portion thereof. This well is joined, by a reduced-cliameter passageway I 6gthrough the end of the cylinder, with the interior of the bellows chamber 23. A metal ball 25 is disposed in the well I61 and seats on the top end of the passageway IIig to close this passageway. An inverted cup memher-26 is 'seatedin the wellIIif-around the ball 25 and has a top WalLsubstantialIy flush with the bottom of the piston chamber I6c, equipped with a small orifice-21 to connect the piston chamber I60 with the interior of the cup around the ball 25. As shown, the ball is free to rise and fall in the cup onto and off of its seat at the top of the passageway I60.

In its free unloaded condition, the tappet II) assumes the extended positionof Figure 1 because the spring I8 urges the piston upwardly to raise it substantiallyout of the piston chamber I6c. This pistonchamber I6c,'the bellows chambers 20 and-23, the passagewaysi l and IE9, and the interior of the cup 26 are allfilled. with hydraulic liquid, such asoil of uniform viscosity even at widely variant temperatures, and extension of the spring I8 with its attendant movement of the piston I1 merely results in free flow of th liquid within the assembly.

The assembly is filled with liquid through the boss 2Ia of the cap 2I, and is purged of all gas bubbles by placing theboss uppermost during the filling operation. The plug 22 seals the liquid within the assembly. If desired, as shown in Figure .4, the boss 2 Ia and plug 22 can be replaced with a smal tube 28 brazed into or integral with the cap 2I and projecting therefrom out of the chamber 23. A Y fitting 29is coupled to the tube by a hose 30 and has valves 3| in the branches 29a and 2% thereof. One branch 29a is connected to a vacuum pump (not shown). The other branch-29bis connected to a source of oil (not shown) or-Otherfluid for the tappet.

The bellows I i thus encloses a chamber 20 be- 1 The valve in branch 29a is opened and the other valve in is closed. The pump is then operated to evacuate'the tappet, and, when theair in the tappet is exhausted, the opened valve 3| is closed and the other valve3I opened, whereupon the oil is drawn into the tappet to completely fill all chambers thereof without admitting any air. Thetube 28 then has the projecting end thereof pinched closedas at 28a (Fig.5) and a drop of solder 32 is applied to the tipof the pinched end to seal the tappet.

When-the tappet III-is mounted for operation in the valve train of an internal combustion engine, for example, as shown in Figure 2, the body II-has its cylindrical sidewall IIb slidably mounted in the engine block 18- and has its closed bottom IIa acted on by the-engine cam C. The recess I-Sbof the top cap I9 receives the 5. valve push rod P. With the engine valve (not shown) in closed position,'the valve spring (not shown) exerts some downward pressure on the push rod P which is transmitted through the cap ill to slightly compress the spring [8 thereby forcing the piston l1 partly into the piston chamber 160, preferably about half way between the top and bottom of the piston chamber. Thus, the tappet assumes a somewhat contracted position when mounted in a valve train even when the valve is completely closed and the tappetis not transmitting force for opening the .valve. This contracted position is readily assumed from the free expanded position of Figure 1 by flow of liquid from the chamber 20 through the passageway 24 into the chamber 23 whereupon the chamber. 20 partially collapses and the chamber 23 expands. Liquid that was trapped in the piston chamber I60 can leak from this chamber alongside of the piston 11 into the chamber 20 at a relatively slow rate since the piston IT has a rather free sliding fit in the cylinder bore I6b. Back flow of liquid from the chamber I60 through the passageway IBg into the chamber 23 is prevented by the ball 25 which acts as a check valve in seating on the mouth of the passageway 16g.

When the cam C rotates in the direction shown by the arrow, the cam lobe C thereon raises the valve body I l and this lifting movement is transmitted to the shell l3 which, in turn, transmits it to the cylinder l6. Liquid trapped in the piston chamber I60 by the ball 25 bottoms the piston l1 and causes it to rise with the cylinder 16. The piston l I thrusts against the cap I9 thereby raising the push rod P. During this lifting operation of the valve-opening cycle, some liquid will leak along the piston I! out of the chamber IBc thereby permitting the piston to move further into the chamber lBc and creating a clearance in the valve linkage. This clearance is controlled by the degree of leak-down ermitted around the piston and, of course, the degree of leak-down is controlled by the relative sizes of th piston and cylinder bore. For example only, and not by way of limitation, if the total movement of the piston I! from its free position at the top of the piston chamber I60 shown in Figure l to a completely collapsed position where it is bottomed on the cup 26 is one-eighth of an inch, the tappet, when installed in an engine, has the piston positioned as shown in Figure 2 midway between the top and bottom of the piston chamber I60. From this midposition, the piston can move one-sixteenth of an inch in either direction thereby being capable of adjusting the effective length of the tappet in either direction a distance of one-sixteenth of an inch. If the leak-down during the entire valve-opening cycle of operation caused by movement of the tappet with the lobe C of the cam from the point of initial contact with the lobe to the point where the round part of the cam acts on the tappet is .002 inch, there exists a clearance in the linkage of .002 inch as the cam lobe rotates past the tappet. At this point there are three conditions which might exist.

First, if the eifective length of the Valve linkage has remained constant during the lift-cycle around the cam lobe, the piston I1 is immediately biased outwardly .002 inch by the spring l8 and/or bellows l4 and I5, and the flow of working fluid from the spaced chambers 23 to I60 takes place and the fluid is trapped in piston chamber lBc by the check ball 25. Therefore, the

next :lift-cycle begins at substantially zero clearance in the valve.

Secondly, .if, in addition to the leak-down of .002 inch, the effective length of the valve linkage has decreased, for example .001 inch, there will be a clearance of .003 inch in the linkage as the lift-cycle is completed. In that case, the piston I1 is biased outwardly .003 inch and the working fluid will fill the piston chamber I60 so that the next lift-cycle will again begin with substantially zero clearance.

Thirdly, 'if in addition to the leak-down of .002 inch, the valve linkage has increased in length, for example .001 inch, a .001 inch clearance would result at the completion of the liftcycleand the piston I! would only be biased outwardlyfor this distance and a corresponding amount of fluid would be trapped in the piston chamber so that the lift-cycle would begin again with substantially zero clearance.

During overspeeding of an engine, or as a result of faulty cam design, it occasionally happens that the tappet will lose contact with the cam face for short periods of time. This is known as cam jumping, and, during the interval of time in which the jump takes place, the tappet is free to extend itself. If this unwanted extension per lift-cycle isgreater than the leak-down per liftcycle, the valve will eventually be held off of its seat between lift cycles and thereby result in malfunctioning of the engine. The tappet of this invention, on the other hand, minimizes unwanted extension during cam jumping periods by providing the restricted fluid flow orifice 21, and also by restricting the passage l6g so that the rate of fluid flow is choked. This choking of the working fluid slows down extension of the tappet sufliciently so that substantially no extension will result in those very short periods of time when the tappet leaves the cam. By properly calibrating the size of the orifice 21 and the flow capacity of the passageway lGg, the unwanted extension of the tappet can be substantially eliminated.

The shell l3 may become heated when the bellows l4 and I5 are welded thereon, but this heat does not affect the separate cylinder I6 which is preferably heat-treated for hardness properties. The cylinder [6 can fit rather freely in the shell l3, and may be free to turn therein without blocking the passage 24. Likewise, the piston ll floats in the cylinder I5, since it is not anchored to a bellows and only thrusts against the cap l9. This movable relationship of shell, cylinder, and piston, together with parts carried thereby, minimizes galling or scufiing action on closely mated parts and eliminates torsion strains on the bellows. A

Because the ball check valve coacts with the cylinder and not the piston, it can be springless and operate efficiently due to fluid pressure differentials alone.

From the above descriptions it will be understood that this invention provides a self-contained automatic hydraulic tappet having bellows chambers at opposite ends of a shell surrounding a separate piston-containing cylinder. The addition of the piston to the self-contained bellows arrangement for carrying all lifting forces greatly increases the wear life of the tappet and minimizes danger of rupturing of any fluid-containing passages.

It will, of course, be understood that various details of construction may be varied through a wide range without departing from the prin-' fats-53,756

ciples of .thisinvention and itis, therefora'not the purpose to limit the patent 'grantedhereon otherwise .than necessitated by the scope of the appended claims.

I claimasmy invention:

1. An extensible and contractible device comprising a shell, an open-ended cylinder in the shell, a check valve in one end of the cylinder controlling flow into the cylinder, a pistonrotatable and slidable in the other end of 'thecylinder, fluid-filled interconnected expansible and contractible chamber-defining members secured to opposite endsof'the shell and communicating with opposite ends of the cylinder, a cap secured to one chamber-defining member and acted on by said piston, means biasing the piston outwardlyrof the cylinder against said cap, said pistoni'being freely slidable in said cylinder to accommodate restricted flow of fluid around the piston whenever the cap loads the piston and fluid in the cylinder is loaded by the piston and being 'free to creep with respectto said cylinder in a rotational direction, and means connecting the expansible and contractible chambers for transfer of fluid therebetween whereby fluid leaking around the loaded piston is fed to one of -said chambers and then transferred to the other of said chambers forflow through the check valve into the cylinder to bottom the piston as soon as it is unloaded'and biased outward by the spring.

2. A self-contained hydraulic valve tappet comprising a shell, .an open-ended cylinder rotatably seatedin said shell, a valve-driving piston rotatable and slidable in said cylinder, means for liftingsaid shell and cylinder to load the piston, resiliently eXp-ansible fluid-filled chamberdeflning means anchored on the ends of the shell and respectively closing the open ends of the cylinder, a check valve accommodating fluid flow from one expansible means to the piston and stopping reverse flow of fluid to trap fluid between the cylinder and piston for driving the valve, said piston being freely fitted in said member to accommodate leakage of fluid therearound when said means for lifting loads the piston thereby creating a clearance in the valve linkage during the valve-lifting cycle and being free to creep with respect to said cylinder in a rotational direction, and a gapbetween the shell and cylinder defining a conduit for transferring the fluid from one expansible chamber-defining means to the other irrespective of the angular position of said cylinder relative to said shell for feeding through saidcheck valve to the piston as soon as saidmeans for lifting releases the load on the piston.

3. A clearance-eliminating device comprising a hollow open-ended sheath, a cylinder seated in said sheath, a spring metal bellows welded to the ends of said sheath and defining expansible and contractible chambers communicating with said cylinder and having end walls spaced outwardly from the cylinder and sheath, a piston slidable in said cylinder and extending into one of said chambers for thrusting against the end wall thereof ,a chest: valve interposed in said cylinder between the other of said chambers and the piston, means interconnecting said chambers for fluid flow, means biasing said piston outwardly of said cylinder against said end wall, said piston being freely slidable insaid member and accommodating leakage of fluid therearound and being free to creep with respect to said cylinder in a rotational direction, said cylinder and chambers :for transferring the axial force to said end wall while some fluid leaks around the piston and is transferred back to the check valve for reintroduction into'the enember upon cessation of the axial force.

4. vA self-contained hydraulic valve tappet comprising a hollow open-ended shell, spring metal bellows at the ends of said-shell defining expansible and contractiblechambers, one of said bellows being closed by an end cap having a recess adapted to receive :a push rod, the other of said bellows being closed by an end cap having a fluid charging nipple thereon, a hollow cylinder disposed in said shell andmounted therein for creeping movement with respect thereto in a rotational direction a check valve interposed between the interior of said cylinder and said other of said bellows, a piston freely rotatable and slidable in the cylinder on the discharge side of the check valve, .a spring interposed between the cylinder and piston biasing the piston against the end cap for receiving the push rod, and means defining a flow path between the chambers housed by the bellows, said piston being freely slidable in said cylinder and accommodating a leakage of fluid around the piston during the valve-lift cycle whereupon said fluid is transferred back to the cylinder and trapped beneath the piston by said check valve as soon as the lift-cycle is completed.

5. A self-contained hydraulic valve tappet which comprises a hollow body, a shell projecting into the body and bottomed thereon, a hollow cylinder seated in the shell and rotatable therein, first and second fluid-filled bellows each having one end thereof afiixed to the shell and defining chambers communicating with the interior of the cylinder, caps closing the outer ends of the bellows, a piston slidable and rotatable in the cylinder and'arranged to'have one end thereof thrust against one of said caps and the other end thereof terminate in said cylinder, a check valve controlling fluid flow between said other end of the piston and the adjacent bellows, and a restricted passageway connecting the interiors of both bellows whereby fluid trapped between the check valve and the piston will transmit valvelifting force through thepiston to the end cap actuated thereby while some trapped fluid leaks into the bellows to be fed on the valve-closing cycle in required amounts to the cylinder for maintaining zero clearance.

6. In a self-contained hydraulic valve tappet ofthe'opposed bellows, cylinder and piston type, the improvement of a separate sheath surrounding thecylinder and sealingly anchoring the inner ends of the bellows, said cylinder and said piston being mounted in said sheath free from said bellows, for creeping rotational movement with respect thereto, whereby said cylinder and piston may rotate relative to said sheath and relative to each other, whereby said cylinder may rotate relative to said sheath and the piston.

'7. In a self-contained hydraulic valve tappet having a cylinder, a piston slidable and rotatable therein and a bellows defining an expansible fluid chamber communicating with the cylinder, the improvements of a shell around the cylinder, a sealing connection from one end of said shell to one end of the bellows, an end cap, and a sealing connection between said end cap and the other end of the bellows, a spring biasing the piston against said end cap and said piston and cylinder being free from said bellows, whereby both said piston and cylinder may shift rotationally.

8. In a self-contained hydraulic valve tappet having a reciprocably movable body, a shell mounted in said body for movement therewith, a cylinder in said shell, a piston within said cylinder, spring means urging said piston in an extended position with respect to said cylinder, an end cap adapted to be engaged by the upper end of said piston, a restricted fluid passageway from the lower end of said cylinder to said piston, a check valve therein, said piston being mounted in said cylinder with a predetermined clearance, to form a restricted passageway along the walls of said cylinder from the lower to the upper end thereof, a fluid passageway between said cylinder and shell allowing fluid to pass from one end of said cylinder to the other, the improvements comprising separate bellows closing and forming expansible chambers at opposite ends of said shell and communicating with opposite ends of said cylinders, sealing connections between said bellows and opposite ends of said shell and a sealing connection between one of said bellows and said end cap, said bellows being so constructed and arranged as to be entirely free from said piston and cylinder and to permit rotational creeping movement of said cylinder with respect to said shell and rotational creeping movement of said piston with respect to said cylinder.

9. In a self-contained hydraulic valve tappet having a reoiprocably movable body, a shell mounted in said body for movement therewith and for rotational creeping movement with respect thereto, a cylinder in said shell, a piston within said cylinder and a chamber within said cylinder into which the lower end of said piston moves, spring means urging said piston in an extended position with respect to said chamber, a restricted fluid passageway into said chamber and a valve in said passageway holding fluid under pressure therein, said piston being mounted in said cylinder with a predetermined amount of clearance to form a restricted passageway allowing a predetermined volume of fluid to leak thereby, a fluid passageway between said shell and cylinder communicating from one end thereof to the other, expansible bellows extending from opposite ends of said shell, sealing connections between said bellows and shell, a closure plate sealed to the lower of said bellows and forming an expansible chamber at the lower end of said cylinder, and the closure member for the upper of said bellows comprising an end cap member sealed thereto, free from and adapted to be abutted by the outer end of said piston.

10. In a self-contained hydraulic valve tappet having a reciprocably movable body, a shell mounted in said body for movement therewith and for rotational creeping movement with respect thereto, a cylinder in said shell, a piston within said cylinder and a chamber within said cylinder into which the lower end of said piston moves, spring means urging said piston in an extended position with respect to said chamber, a restricted fluid pasageway into said chamber and a valve in said passageway holding fluid under pressure therein, said piston being mounted in said cylinder with a predetermined amount of clearance to form a restricted passageway along the walls of said cylinder allowing a predetermined volume of fluid to leak thereby, a fluid passageway between said shell and cylinder communicating from one end thereof to the other, expansible bellows extending from opposite ends of said shell, sealing connections between said bellows and shell, a closure plate sealed to the lower of said bellows and with said bellows forming an expansible chamber extending from the lower end of said cylinder, and the closure member for the upper of said bellows comprising an end cap member sealed thereto and free from and adapted to be abutted by the outer end of said piston, said end cap member affording a means for actuating a push rod of the valve opening mechanism and being so constructed and arranged as to be engaged with said piston and permit creeping movement of said piston with respect to said cylinder and end cap in a rotational direction.

HERBERT H. ENGEMANN.

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

UNITED STATES PATENTS Number Name Date 2,098,115 Voorhies Nov. 2, 1937 2,109,459 Best Mar. 1, 1938 2,109,899 Van Ranst Mar. 1, 1938 2,278,963 Arola Apr. 7, 1942 2,325,932 Banker Aug. 3, 1943 2,376,182 Peterson, Jr. May 15, 1945

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