US3177857A - Self-adjusting hydraulic valve lifter for piston engines - Google Patents

Description

April 13, 1965 R. KucHEN ETAL 3,177,857

SELF-ADJUSTING HYDRAULIC VALVE LIFTER FOR PISTON ENGINES Filed Feb. 27,' 1964 /NVF/VPS RICHARD KCHEN HANS-JRGEN so ss NA ,47 rom/5X5 United States Patent Otiice 3,177,857 Patented Apr. 13, 1965 3,177,857 SELF-ADJUSTING HYDRAUUC VALVE LIFTER FOR PISTON ENGINES Richard Kuchen and Hans-Jurgen Sossna, both of Ingolstadt, Germany, assignors to Motornak, G.rn.b.H-, Ingolstadt, Germany, a corporation of Germany Filed Feb. 27, 1964, Ser. No. 347,783 Claims priority, application Germany, Mar. 2, 1963, M 55,967 2 Claims. (Cl. 12S-90) This invention relates to a self-adjusting hydraulic valve litter for piston engines. The valve lifter comprises two longitudinally slidable, telescoped parts forming a pressure chamber between them, which is connected by means of a check valve with an antechamber located in one of the two pants, sa-id antechamber in turn being supplied with hydraulic oil from the lubricating oil cycle of the engine through bore holes.

Briefly stated, the action of such valve litters is that they consist of structural elements inserted between a valve cam and a valve stem, said structural elements consisting of two telescoping, mutually longitudinally slidable parts, of which one co-operates with the valve cam and the other with the valve stem. The hydraulic selfadjustment of such valve litters to achieve a valve clearance of zero is eleoted by introducing oil from the lubricating I.cycle of the engine into the space between the two parts which form the valve lifter, and closing oli the pressure chamber, which receives this oil, toward the outside by means of a check valve.

When the two parts which form the valve litter are pressed apart so far that they abut without clearance -against the valve cam and the valve stem, respectively, 'and the pressure chamber defined by these two parts is completely filled with oil, a lifter is formed which, for practical purposes, provides a rigid coupling between the valve cam and the valve stem.

Such valve litters are disclosed in our copending application entitled Self-Adjusting Hydraulic Valve Litter for Piston Engines. K

It is known that when piston engines run at a very high number of revolutions per unit time, the inherent mass forces of the valves themselves and of the other valve control parts, such as the valve rocker, the valve stem and the valve lifter, sometimes become so great that they overcome the force of the valve spring. The result is that the valve opens farther than it actually Vshould,'based on the shape of the cam, whereby a certain amount of clearance play occurs between the individual parts of the valve control.

From what has been said above, it follows that when e known hydraulically self-adjusting valve lifters are used, they have the tendency to eliminate any clearance play which may occur in the valve control. When, at a high number of revolutions per unit time, the abovedescribed sequence occurs, thetwo parts of such a valve lifter therefore separate to such an extent that the clearance play is eliminated. However, this means that during the subsequent down stroke the valve can no longer return to its 'fully seated position. The consequences resulting from this, namely, scorching of the valve scat, are well known.

It is, therefore, an object of this invention .to provide a hydraulic valve lifter which automatically adjusts to inertial forces at high engine speed.

A further object is .to provide a hydraulic valve lifter which is self-adjusting and returns the valve to a fully seated position when closed.

These and other objects of our invention will become app-arent as the description thereof proceeds.

The present invention eliminates this disadvantage of the known hydraulically self-adjusting valve litters by the fact that the bore holes through which hydraulic oil is fed into the antechamber of the lifter are arranged in such a way that the oil supply is interrupted when the litter has passed through a portion of its total litt stroke. The invention i's based upon the consideration that the adjustment action fof the valve lifter needs to take place only when .the associated valve is in its closed position, that is, when the lifter is in its bottom dead-center position. During the subsequent opening and closing sequence of the valve, no adjusting means needs to be provided for Ithe valve lifter; instead, as described above, it can only have a disadvantageous effect.

The present invention, therefore, proposes to overcome this disadvantage 'by means of an element of structure, namely, by arranging the bore holes, through which hydraulic oil is fed from the lubricating oil cycle of the engine into the antechamlber, in such a way that the oil supply is linterrupted when the lifter has passed through a portion of its total lift stroke. In this manner, therefore, the lifter is supplied with oil only at the beginning of its lift stroke, whereas in the last portion of the lift stroke the oil supply is stopped, so that a further adjustment of the lifter is no longer possible.

From the viewpoint of structure, this may be accomplished in simple fashion by providing the outside portion of the valve ylifter with a cincumscribing annular groove in which the bore holes leading to the antechamber terminate, the annular groove being so wide and being arranged at such a place on the lifter that the lubricating oil channels, Iwhich terminate in the bore of the engine block that :serves to guide the lifter, are Within range of this groove only When ythe valve .litter is in its bottom dead-center position and at the beginning of its litt stroke.

It is known that in many instances several valve litters positioned in series are supplied with oil :from the lubrieating oil .cycle through a single bore, so that a series conneotion of the individual `litters results. In such a case,

care must be taken that, even when one of the liftens blocks oil bore, the lifters in subsequent series position are still adequately supplied with oil. For this purpose it is proposed according to the present invention to provide another 'annular groove, in addition to the above mentioned annular groove, which is not connected with the inner portion of the valve lifter, but rather exclusively serves to create a bypass channel which comes into play when the particular valve lifter has shut otfthe oil supply into its antechamber.

, The invention may be better understood by referring to the drawing which shows an embodiment of the above describedvalve litter in longitudinal cross-section.

In the drawing reference numeral 1 designates the entire valve lifter Whose disc 2 abuts against valve cam 3 and which, on the other end, abuts by means ot ball socket 4 -against the spherical end 5 of valve stem 6. The valve lifterl consists .essentially of a casing 7 Vwhich is closed oi at one end by disc 2 'and on the other end by a telescoping element 8 which is connected with ball socket 4 into a solid structural element.

The two elements 7 and 8 are telescoped and longitudinally slidable with relatively large clearance play and are sealed from each other by annular rope gaskets 9. Housing 7 is also longitudinally slidably positioned in a bore 10 of engine block 11. Engine block 11 is provided with a lubricating oil channel 12 which terminates in bore 10, the lubricating oil channel being connected to the oil circulation of the engine. In the area where channel 12 terminates in bore 10, housing 7 is provided on its outer circumference Iwith two adjacent annular grooves 13 and 13a. In the area of groove 13, housing '7 is provided with a plurality of bore holes 14 uniformly distributed over the circumference, whereas in the'areaY of groove 13a no such bore holes are provided.

In the area in which bore holes 14 terminate, the sliding element 8 guided within housing 7 is also provided with a plurality of bore holes 16 distributed over the circumference. These bore holes 16 ultimately ter-A minate in the antechamber 17 provided within the sliding element 8, said antechamber being defined by the sliding element 8 and axially by ball socket 4 on one end and by valve plate 18 on the other end.

Valve plate 18, which is under the action of a leaf spring 19, closes off antechamber 17 from pressure chamber 20 which in turn Vis located within housing 7. For positioning of valveplate 1S and leaf spring 19 a housing 22 is provided which may, for example, be drawn from sheet metal. A coil spring 21 is mounted within pressure chamber'Zt), this coil spring having a tendency to force apart the axially slidable parts 2 and 7 on the one hand and 4 and 8 on the other hand. The most extreme sliding position is determined by a ring 23 mounted in a bore of housing 7 against which the ball socket 4 abuts.

Housing 7 comprises in the area of pressure chamber 29 plurality of vent bores 24 uniformly distributed over its circumference, which serve to bleedrotf air which may possibly be introduced with the oil into pressure chamber 20. Finally, casing 25, which overlaps the vent bores 24 and thereby forms a4 narrow annular slitv with the inner wall of the pressure chamber 20, serve for throttling these bore holes 24.

The essential element of the present invention is the annular groove 13 in housing 7. As the drawing shows,v

the width of this groove 13 is of such size and the 'groove itself is arranged in such a place on the lifter that when lifter 1 is in its bottom dead-center position, as shown in the drawing, oil from the lubricating oil channel 12 can pass through bores 14 and 16 into antechamberr17.

' When cam 3 now rotates in subsequent sequence in the direction of arrow 26 and thereby moves valve lifter 1 from its bottom dead-center position toward the right, the connection between lubricating channel 12 and bore 14 is interrupted after a short displacement by an annular ridge 27 which separates grooves 13 and 13a from each other. Since, beginning from this point of time, no oil can ow from channel 12 into antechamber 17, no further relative sliding displacement of the two lifter elements 2 and 7 and 4 and 8 with respect to each other is possible. Instead, the annular groove 13a passes within the area of bore 12, whereby the lubricating oil. channel 12 is connected with channel 12a indicated by` broken lines, which may serve for supplying oil to the next valve lifter.

While we have disclosed certain preferred embodiments of our invention, it will be understood that this is solelyY for the sake of illustration and to enable persons skilled in the Aart to understand the invention. The invention can be applied to hydraulic valve lifters of varying designs without `departing from the spirit of the invention or the scope of the appended claims.

We claimt, Y l

1. Hydraulically self-adjusting valve lifter for piston engines comprising two vcylindrical longitudinally slidable telescoping members closed at the extreme ends and deiining a pressure chamber between them, an antechamber located in one of the said slidable members, checlr-valve means between said pressure chamber and said antechamber through which said chambers can be connected, channel means to provide hydraulic fluid to said antechamber, said channel means feeding to the guide bore in which said valve lifter moves, a circumferential annular groove on the exterior surface of the valve lifter, bore holes communicating between said antechamber and said annular groove, said annular groove being positioned on the valve lifter so that said hydraulic tiuid feed channel means terminating in the valve lifter guide bore are positioned in the area of said annular groove only when the valve lifter is in its lower dead center position and at the beginning of its lift stroke, a second annular groove on the exterior surface of the valve lifter which is not connected with the inner space of the valve lifter, said second annular groove being positioned to communicate with said hydraulic fluid channel means during the latter stages of the valve lift stroke. y

2. Hydraulically self-adjusting valve lifter for piston engines comprising two cylindrical longitudinally slidable telescoping members closed at the extreme ends and defining a pressure chamber betweenl them, an antechamber located in one of the said slidable members, check-valve means between said pressure chamber and said antechamber through which said chambers can be connected, channel means to provide hydraulic tluid to said antechambenrsaid channel means feeding to the guide bore in which said-valve lifter moves, a circumferential annularr groove on the exterior surface of the valve lifter, bore holes communicating'between said antecharnber and said annular groove, said annular groove being positioned on the valve lifter so that said hydraulic iluid feed channel means terminating in the valve lifter guide bore are positioned in the area of said annular groove only when the valve lifter is in its lower dead center position and at the beginning of its lift stroke, a second annular groove on the exterior surface of the valve lifter which is not connected with the inner space of the valve lifter, said second annularV groove beingv positioned to communicate with said hydraulic fluid channel means during the latter stages of the valve lift stroke and vent bores through the wall of said pressure chamber, for bleeding off gases from said chamber to the outside of said valve lifter.

References Cited by the Examiner UNITED STATES PATENTS FRED E. ENGELTHALER. Primary Examinar.

Claims (1)

1. HYDRAULICALLY SELF-ADJUSTING VALVE LIFTER FOR PISTON ENGINES COMPRISING TWO CYLINDRICAL LONGITUDINALLY SLIDABLE TELESCOPING MEMBERS CLOSED AT THE EXTREME ENDS AND DEFINING A PRESSURE CHAMBER BETWEEN THEM, AN ANTECHAMBER LOCATED IN ONE OD THE SAID SLIDABLE MEMBERS, CHECK-VALVE MEANS BETWEEN SAID PRESSURE CHAMBER AND SAID ANTECHAMBER THROUGH WHICH SAID CHAMBERS CAN BE CONNECTED, CHANNEL MEANS TO PROVIDE HYDRAULIC FLUID TO SAID ANTECHAMBER, SAID CHANNEL MEANS FEEDING TO THE GUIDE BORE IN WHICH SAID VALVE LIFTER MOVES, A CIRCUMFERENTIAL ANNULAR GROOVE ON THE EXTERIOR SURFACE OF THE VALVE LIFTER BORE HOLES COMMUNICATING BETWEEN SAID ANTECHAMBER AND SAID ANNULAR GROOVE, SAID ANNULAR GROOVE BEING POSITIONED ON THE VALVE LIFTER SO THAT SAID HYDRAULIC FLUID FEED CHANNEL MEANS TERMINATING IN THE VALVE LIFTER GUIDE BORE ARE POSITIONED IN THE AREA OF SAID ANNULAR GROOVE ONLY WHEN THE VALVE LIFTER IS IN ITS LOWER DEAD CENTER POSITION AND AT THE BEGINNING OF ITS LIFT STROKE, A SECOND ANNULAR GROOVE ON THE EXTERIOR SURFACE OF THE VALVE LIFTER WHICH IS NOT CONNECTED WITH THE INNER SPACE OF THE VALVE LIFTER, SAID SECOND ANNULAR GROOVE BEING POSITIONED TO COMMUNICATE WITH SAID HYDRAULIC FLUID CHANNEL MEANS DURING THE LATTER STAGES OF THE VALVE LIFT STROKE.

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