US2098115A - Hydraulic valve lifter - Google Patents

Description

Nov. 2, 1937. c. vooRHu-zs HYDRAULIC VALVE LIFTER IN VENTOR lariz'e 5.

Carl

Filed Feb. 10, 1936 ATTORNEYS.

Patented Nov. 2 1937 UNITED STATES HYDRAULIC VALVE LIFTER,

Carl Voorhies, Detroit, Mich, assignor, by mesne assignments, to Eaton Manufacturing Company, Cleveland, Ohio, a corporation of Ohio Application February 10,-1936, Serial No. 63,187

15 Claims.

The invention relates to automatic adjusting hydraulic tappets for use in transmitting motion between machine parts, and particularly for use in transmitting motion between the cam shaft 5 and a valve of an internal combustion engine.

One object of the invention is to provide a hydraulic tappet of the type mentioned wherein means are incorporated within the unit for separating air and gas bubbles from the operating liquid in order to provide a body of liquid within the compression chamber of the tappet which is substantially incompressible.

Another object of the invention is to provide an improved self-contained hydraulic tappet of the type mentioned wherein the operating fluid is permanently and hermetically sealed within the unit where it is free from contamination.

In Diesel engines it is common practice to lift the exhaust valves off their seats to assist in starting the engine and in all prior hydraulic tappet installations this could not be done without permitting a false compensation .of the hydraulic tappet unit. Accordingly, it is a further object of the invention to provide means for lifting the valve of an internal combustion engine for starting or other purposes, without permitting a false setting of the hydraulic tappet unit.

I Other objects and advantages of the invention will become apparent from the accompanying drawing and appended specification and claims.

Referring to the drawing wherein like numerals are applied to like parts in the several views:

Figure l is a fragmentary vertical section through an internal combustion engine and a hydraulic tappet unit installed therein.

Figure 2 is a horizontal section taken on the line 2--2 of Figure 1.

Figure 3 is a sectional view of a modified form of self-contained tappets.

Figure 4 is a sectional view of a further type of self-contained tappet. v

Figure 5 is a fragmentary vertical section through an internal combustion engine showing a hydraulic tappet unit equipped with means for lifting the valve of the engine without interfering with the adjustment of the tappet.

Referring to Figure 1 there is shown a portion of the cylinder block Ill, and the lower end of a valve rod II of an internal combustion engine. The engine block is provided with a vertically extending bore I2 for the reception of a selfadjusting hydraulic tappet mechanism indicated generally at I3, which is adapted to be engaged and operated by a cam I4 on the engine cam shaft IS. The hydraulic tappet unit comprises a cylindrical casing I6 having a solid bottom wall I'I adapted to be engaged by the cam. The casing is hollow and contains a pair of spaced transverse partitions I8 and I9 in which are provided aligned openings adapted to receive a cylinder which extends above and below the respective partitions I8 and I9; and engages the bottom wall I! of the casing I6. The lower end of cylinder 20 is provided with an opening 2I communicating with a transverse slot 22 in the end of the cylinder. An annular seat 22 for a ball valve 23 is inserted in the reduced end of the cylinder 20 adjacent the opening 2|; and a ball valve 23 is retained in juxtaposition to the seat by means of a cage 24 having a radially offset opening 25 for the passage of fluid from opening 2I into the interior of the cylinder 20.

As a result of this construction, it will be observed that the casing I6 is divided into a lower chamber which is in communication with the lower end of the cylinder 20 through opening 2I,

an intermediate chamber 3| which is in communication with the lower chamber 30 through a slot 32 and with the exterior of the casing I6 through an opening 33, and an upper chamber 34 which is open at the top. It is apparent that liquid within the lower chamber 3|! may flow through slot 22, opening 2I and past the ball valve 23 into the interior of the cylinder 20 through opening 25, but that flow in the opposite direction is prevented by the ball valve 23 engaging its seat 22.

A plunger 35 is fitted within the cylinder 20 and is provided at its upper end th a piston rod having an enlarged head 36 ada ted to engage and operate the engine valve rod II. A coil spring 31 is positioned between the upper end of the cylinder 20 and a shoulder on the under side of head 36; and this spring operates to urge the piston 35 upwardly into engagement with the engine valve rod I I at all times. that the engine valve rod II is constantly urged downwardly by means of the conventional engine valve spring (not shown). Spring 31 is considerably weaker than the engine valve spring with the result that it cannot effect movement of the engine valve rod I I, but merely operates to maintain the head 36 of plunger 35 in engagement with the valve rod II.

Casing I6 adjacent port 33 is provided with an annular peripheral recess 40 opposite a passageway II in the engine block. It will be observed that the axial extent of the recess 40 is sufficient to maintain the recess opposite the inner end of passageway ll regardless of the It should be noted,

movement of the casing |6 under the influence of cam ll.

In operation, oil from the oil pump of the internal combustion engine, or from any other desired source, is supplied under pressure through passageway 4| and thence through recess 46 and port 33 to the intermediate chamber 3| of easing l6. From the intermediate chamber 3| the oil may flow through slot 32 in partition l9 into the lower chamber 30, from which point it may flow through slot 22 and port 2| into the interior of the cylinder below piston 35. It should be noted that port 33 is positioned below the upper margin of recess 40 with the result that there is a tendency of any air or gas bubbles in the incoming oil to collect in the upper portion of the recess and to be forced outwardly between the engine block and easing |6. In addition, it should be noted that slot 32 in partition I3 is positioned diametrically opposite the port 33 with the result that there is ample opportunity for oil, after it reaches chamber 3| and before it passes downwardly into chamber 36, tofree itself of air or gas bubbles. The bubbles which separate out of the oil in chamber 3| and collect at the top thereof are forced outwardly between cylinder 23 and the margins of the opening in partition l8. The partition l9 serves to separate the oil in chamber 3| which may not be entirely free from air or gas bubbles from the oil which has passed downwardly through slot 32 into the lower portion of the casing l6. The upper partition |3 normally serves to prevent splashing and churning of the liquid in chamber 3| since ordinarily this chamher is completely filled with oil. It will be ob-- served that if the chamber 3| were open at the top, the oil would splash and collect air bubbles which might pass downwardly into the lower chamber, and that this is prevented by partition l6 which permits the discharge of any air which may be carried into chamber 3| with the oil and prevents the formation of additional bubbles during the violent reciprocation of the casing.

In operation, the forces transmitted by cam II to the bottom wall of casing |6 are transmitted through the cylinder 26 and the body of oil which is trapped within the lower end of cylinder 20 by valve 23 to the plunger 35 and thence to the valve operating rod As long as the plunger head 36 remains in contact with the lower end of the engine valve rod, this method of operation will continue, the unit operating as a solid tappet. However, if for any reason a clearance should develop between the plunger head 36 and the bottom of the valve rod'il, spring 31 will immediately urge the plunger and head 36 upwardly and again into engagement with the bottom of valve rod II. This movement of the plunger will draw in fluid from the lower chamber 36 through slot 22 and port 2| past the valve 23 and the unit will continue to operate as before, having corrected the maladjustment. It should be noted that due to leakage between the plunger 35 and the walls of the cylinder 20 there is a slight tendency of the plunger to be moved downwardly in the cylinder during the valve lifting stroke. This of course places the unit out of adjustment, but this maladjustment is negligible and is automatically corrected as soon as the engine valve is seated by means of spring 31 in the same manner as maladjustment caused by any other factor. The fact that a slow leakage may occur past the plunger makes it possible for the valve spring, not shown, to eifect a downward compensating adjustment of the unit when aooaua the valve rod elongates due to increase in its temperature.

In Figures 3 and 4 is shown the application of the improved air separation partitions to a hy draulic tappet unit of the self-contained and hermetically sealed type. In the modification shown in Figure 3 the casing 56 is provided with a pair of spaced partitions 5| and 52 having central openings in which the cylinder 53 is mounted. The cylinder 53 is provided with a check valve 54 arranged in the manner indicated with respect to the construction shown in Figures 1 and 2. In the construction of Figure 3, however, a plurality of small radially extending slots 55 and 56 are provided around the openings in partitions 5| and 52, respectively, to permit the passage of liquid past the partitions. The plunger 60 is provided with an integral head 6| adapted to be engaged and urged upwardly by a helical spring 62, the lower end of which seats against the top of the cylinder 53. The plunger 66 and head 6| are provided with an axially extending drilled hole 63 which is threaded at its upper end for the reception of a cap screw 64. This cap screw is utilized to engage the engine valve rod 65 and to clamp the inwardly directed edges of one end of a sylphon bellows 66 to the head 6| to provide a fluid-tight connection between the bellows and the plunger. The opposite or lower end of the sylphon bellows 66 is flanged outwardly and is clamped in sealing relation with the upper end of the casing 50 by means of an annular ring 61, which is threaded into the upper open end of the casing 50 and cooperates with an internal shoulder on the casing.

When the device shown in Figure 3 is assembled, sufiicient operating liquid is placed within the casing 50 to raise the liquid level approximately to the upper surface of the partition 5| when the cylinder 53 and plunger 66 are assembled in operating position, thus leaving an air space within the sylphon bellows. The device is preferably assembled and the bellows sealed to the casing and to head 6| with the plunger 63 in an elevated position with respect to its normal operating position. Thus, when the piston assumes its normal working position, it will have forced from the cylinder 53a volume of liquid whichpasses into the space between cylinder 53 and casing 56, thereby compressing the air under the sealed diaphragm or sylphon bellows 66. The total pressure can be controlled by the amount the plunger is elevated above normal at assembly and by the proportion of the air space within the bellows or diaphragm. The provision of this positive pressure'within the unit at all times tends to prevent the formation of gas pockets and aids in forcing liquid past the check valve 54 into the cylinder 53 when the piston 66 moves upwardly to make a compensation.

Any suitable liquid that will not attack metal or vfreeze, vaporize or disintegrate under the operatingtemperatures and conditions may be used. Among examples of suitable liquids are lubricating oils, glycerin, ethylene glycol, diethylene glycol, triethylene glycol and propylene glycol.

In operation, the hydraulic tappet unit shown in .Figure 3 functions in the manner described with respect to the unit shown in Figures 1 and 2, the partition 5| operating to prevent splashing and churning of the liquidbetween partitions 5| and 52 and the partition 52 serving to segregate gasfree liquid in the lowermost chamber below partition 52. In addition, inasmuch as this unit is self-contained and sealed against the loss of liquid tit or entry of foreign matter, it is possible to select a liquid which is peculiarly suited to the operation of the tappet unit, and once the unit is assembled, there is no possibility of loss or contamination of that liquid.

The modification shown in Figure 4 is similar to that shown in Figure 3 except that a coil spring 10 for urging the plunger 1| upwardly in cylinder 12 is positioned within the cylinder and bears against a surface on the lower end of the plunger, instead of being mounted upon the top of the cylinder as in the modifications previously described. The arrangement shown in Figure 4 lends itself to the use of a flat diaphragm in place of a sylphon bellows, and such a diaphragm is shown in Figure 4 at 13. The diaphragm is clamped to the casing 14 by means of a threaded cap 15. In all other respects the modification in Figure 4 is similar to and operates like that shown in Figure 3, previously described.

In Figure is shown a modified form of hydraulic tappet unit of the type shown in Figures 1 and 2 and which is particularly adapted for use on Diesel engines or other heavy internal combustion engines wherein the exhaust valves are lifted during starting. In this form the cylinder block 80 is bored to receive the casing 81 of the hydraulic tappet unit. The casing 8| is provided with spaced partitions 82 and 83 and a recess 84 in the bottom wall 85. In this construction the cylinder 88 is carried by a sleeve-like member 81 which is closed at its lower end to prevent downward movement of the cylinder with respect to the sleeve member 81. The lower end of sleeve 81 extends into the recess 84 and is of slightly smaller diameter than the recess; and the bottom wall of sleeve 81 is slotted at 88 in order that liquid within the chamber below partition 83 may flow downwardly into the space between the walls of recess 84 and the sleeve 81 and thence through the slot 88 and port 89 of the cylinder to the one way valve 90.

In this construction the plunger 9i is provided with a central opening extending throughout substantially its entire length for the reception of a thrust member 92, which is loosely mounted within the plunger. The upper end of the thrust member 92 is inserted within a hollow end portion of the engine valve rod 93 and an intermediate shoulder 94 on the thrust member 92 abuts the end of the valve rod 93 and transmits the valve lifting force thereto. As in the prior constructions, a spring 95 is provided between the top of the cylinder 88 and an upward extension of the plunger 9| for the purpose of urging the plunger upwardly and into abutment with the engine valve rod.

Sleeve 81 is extended upwardly above the tappet unit and is flanged outwardly at 96 to provide a surface adapted to be engaged by a camrning surface 91 on a rotatable shaft 98 carried by the engine block. When it is desired to start the engine the shaft 98 is rotated clockwise as viewed in Figure 5 by any suitable means, whereupon the camming surface 91 engages beneath the flange 96 and lifts the sleeve 81, the cylinder 85 and plunger 9| without changing the relative position of the cylinder and plunger and therefore without interfering with the setting or adjustment of the hydraulic tappet unit. As soon as shaft 98 is re-rotated or returned to the position shown in the drawing, the engine valve spring (not shown) will return the parts to their operative positions shown in Figure 5. It should be noted that where a non-adjusting tappet is used, any part of the valve train may be lifted to open the valve during starting and hence no difllculties are presented. In installations including self-adjusting valves, however, advancement of any part of the valve train beyond the hydraulic cylinder will cause the piston to compensate, and when the parts are returned to their normal position, the valve will be held open for a considerable time until a relatively large amount of liquid leaks past the piston and will thus prevent starting of the engine. It is for this reason that it is necessary, as in Figure 5, to associate the compresslon release cam 91 with the cylinder of the hydraulic tappet.

The modification shown in Figure 5 is in all other respects than those specifically mentioned like that shown in Figures 1 and 2 and functions in the same manner.

While several modifications of the invention have been shown, it is apparent that others may be utilized within the spirit of the foregoing description, the accompanying drawing and claims hereinafter set forth.

What is claimed is:

l.- A hydraulic valve tappet comprising a casing adapted to be engaged and moved by a tappet operator, a cylinder in said casing, a piston in said cylinder, said cylinder having an inlet port, and meanspositioned within said casing and exteriorly of said cylinder for separating gas from liquid in said casing before it enters said cylinder P rt.

2. A hydraulic valve tappet comprising a casing adapted to be engaged and moved by a tappet operator, a cylinder in said casing, a piston in said cylinder, said cylinder having an inlet port,

a one-way valve controlling admission of fluid to said cylinder through said port, and means within said casing and exteriorly of said cylinder for segregating gas-free liquid adjacent said cylinder inlet port.

3. A hydraulic valve tappet comprising a casing adapted to be engaged and moved by a tappet operator, a cylinder in said casing, said cylinder having an inlet port adjacent one end thereof, a one-way valve for controlling admission of fluid to said cylinder through said port, said casing and cylinder having an open space between theirrespective walls, means for separating said open space into two chambers the lowermost of which is in communication with said cylinder inlet port, and a liquid in said chambers.

4. A hydraulic valve tappet comprising a casing, a cylinder in said casing, said cylinder having an inlet port adjacent one end thereof, a oneway valve for controlling admission of liquid tosaid cylinder through said port, said casing and cylinder having an open space between their respective walls, means for separating said open space into three communicating superimposed chambers the lowest of which is in direct communication with the cylinder inlet port, and a liquid in the two lowermost chambers and having its normal level above the intermediate chamher.

5. In an internal combustion engine, an exhaust port, an exhaust valve associated with said port, said valve having a valve rod, a cam shaft for operating said valve through said rod, and a hydraulic tappet unit adapted to be reciprocated by said cam shaft and to reciprocate the valve rod and valve, said unit including a casing, a cylinder movably mounted in said casing, a piston movable in said cylinder, and adapted to operate said valve rod, and means for lifting said cylinder, piston and valve rod as a unit with respect to said casing without altering the relative positions of the piston and cylinder.

6. A self-contained hydraulic tappet comprising a cylinder, a piston in said cylinder, means defining a passage hermetically sealed from the atmosphere for the flow of fluid from one end of the cylinder to the other outside of said cylinder, and a one way valve in said passage for preventing flow in the opposite direction.

7. A self-contained hydraulic tappet comprising a cylinder, a piston in said cylinder, means defining a passage hermetically sealed from the atmosphere for the flow of fluid from one end of the cylinder to the other outside of said cylinder, and means in said passage for segregating and conducting gas-free liquid only.

8. A self-contained hydraulic tappet comprising a cylinder, a piston in said cylinder, an inlet port at one end of said cylinder, a one way valve associated with said inlet port, and means defining a passage hermetically sealed from the atmosphere and exteriorly of said cylinder for conducting fluid from the other end of said cylinder to the inlet.

9. A self-contained hydraulic tappet, including a cylinder, hermetically sealed means encompassing said cylinder, a piston in said cylinder, an inlet port at one end of said cylinder, a one-way valve associated with said inlet port, and means exteriorly of the cylinder and within said first means for conducting fluid from the opposite end of said cylinder back to said inlet port.

10. A self-contained hermetically sealed hydraulic tappet including a cylinder, hermetically sealed means encompassing said cylinder, a piston in said cylinder, an inlet port at one end of said cylinder, a one-way valve associated with said inlet port, means exteriorly of the cylinder and within said first means for conducting fluid from the opposite end of said cylinder back to said inlet port, and gas separation means associated with said last named means.

11. A self-contained hydraulic tappet, including a hermetically sealed casing, means forming a cylinder within the casing, a piston in said cylinder, means including a one-way valve providing a conduit for flow of fluid from one side of the piston to the other exteriorly of the cylinder wall, said casing being partially filled with an incompressible fluid and having the remaining space therein filled with a gas under pres- 511:: in excess of atmospheric pressure at all 12. A self-contained hydraulic tapp'et comprising a sealed casing having a flexible wall, a cylinder within said casing, a piston movable in said cylinder, said cylinder having a port adjacent one end thereof, a one-way valve for admitting fluid into said cylinder through said port, said cylinder having an opening in its opposite end communicating with the interior of the casing, and a passage between the walls of the cylinder and the casing connecting opposite ends of the cylinder, said piston and flexible wall being movable together, and means for urging said piston away from the first mentioned end of the cylinder.

13. A valve lifting mechanism including a reciprocable casing, means for reciprocating the casing, a cylinder mounted in said casing, a piston movable in said cylinder, and means for lifting said cylinder and piston as a unit with respect to the casing without altering the relative positions of the piston and cylinder.

14. In an internal combustion engine, an exhaust port, an exhaust valve associated with said port, said valve having a valve rod, a camshaft for operating said valve through said rod and a hydraulic tappet unit adapted to be reciprocated by said camshaft and to reciprocate the valve rod and valve, said unit including a cylinder, a piston movable in said cylinder, and auxiliary means for lifting said cylinder and piston without altering the position of said piston relative to said cylinder.

15. A hydraulic valve tappet comprising a casing adapted to be engaged and moved by a tappet operator, a cylinder in said casing, said cylinder having an inlet port adjacent one end thereof, a one-way valve for controlling admission of liquid to said cylinder through said port, said casing and cylinder having an open space between their respective walls, means for separating said open space into a pair of communicating superimposed chambers, the lower of which is in direct communication with the cylinder inlet port, said means comprising a partition member extending across the space between said walls and formed with a relatively small passage for the flow of fluid between said chambers, and a liquid in said chambers.

CARL VOORHIES.

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