US2689554A - Hydraulic valve lifter - Google Patents

Description

Sept. 21, 1954 R. c. MOSER 2,689,554

HYDRAULIC VALVE LIFTER Filed July 26, 1950 Patented Sept. 21, 1954 HYDRAULIC VALVE LIFTER Robert C. Moser, Grand Rapids, Mich., assignor to Thompson Products, Inc., Cleveland, Ohio,

a corporation of Ohio Application July 26, 1950, Serial No. 175,964

13 Claims. 7 h l 1 This invention relates to a hydraulic automatic adjuster for taking up clearances in alinkage assembly without, however, causing'the linkage to become too tight so as to interfere with proper operation thereof. Specifically, the invention deals with a hydraulic valve lifter or tappet having a needle valve controlled orifice which will not become clogged with dirt and utilizing a needle valve spring to take up all clearances in the valve linkage.

In accordance with this invention, a spring biased load carrying needle valve cooperates with a spring loaded orificed plunger which is slidably mounted in a hollow body to divide the body into an oil reservoir compartment and a hydraulic fluid force transmitting cavity. The plunger spring holds the plunger against the needle valve to close the orifice thereby separating the reservoir and cavity chambers of the body. The needle valve itself is slidably mounted in the body and is spring biased to an extended position. The

needle valve spring takes up all slack in the valve train and when the body is lifited by the operating cam, oil in the cavity will be trapped to force the plunger to move with the body. However, some oil leak down will occur through the plunger fit in the body and, when the body returns to its initial position after opening the valve, the assembly will be somewhat shorter than its original height due to this leak down. Then when the valve spring load is relieved from the linkage after the valve is seated, the oil pressure in the cavity will drop to zero and the needle valve spring is effective to move the valve away from the plunger orifice, whereupon the oil pressure in the reservoir and cavity are again balanced, balancing pressu es on both sides of the plunger permitting the plunger spring to seat theplunger against the needle valve, thereby again closing the orifice. In the event that any dirt or chips interfere with a complete closing of the orifice, oil will not be trapped in the cavity and on the next valve opening cycle the loaded needle valve will cause the plunger to crash down against a stop thereby crushing or dislodging any such foreign matter with a force that runs up to several thousand pounds per square inch.

A feature of the invention therefore resides in the provision of a needle valve equipped hydraulic valve lifter wherein any dirt lodging on the valve or valve seat will be smashed during the valve opening operation.

Afurther featureof the invention is to provide a hydraulic valve lifter wherein a valve spring takes up all of the slack in the valve train, permitting a weak coacting plunger spring to be used in combination with the valve and preventing vaporization of oil in the force transmitting cavity such as might occur due to the use of a strong plunger spring creating a partial vacuum in expansion of the cavity.

A further feature of the invention is to provide a hydraulic valve lifter which will function efiiciently in extremely cold weather with congealed oil by utilization of a spring to take out all slack in the linkage and produce a wide open orifice which will accommodate flow of congealed oil.

A still further feature of the invention resides in the low cost of the lifter of this invention, since it is capable of opera-ting efiiciently without formation of carefully fitted parts.

It is, then, an object of the invention to provide a low cost hydraulic adjuster.

Another object of the invention is to provide a hydraulic valve tappet or clearance regulator which has a spring loaded needle valve and a plunger actuated valve seat coacting with a stop to smash any dirt that might lodge between the valve and seat and interfere with sealing.

A still further object of the invention is to provide a hydraulic valve lifter wherein a spring loaded needle valve takes out the slack in the valve linkage and wherein a light spring loaded orificed plunger coacts with the needle valve to selectively join and separate opposed oil compartments.

Other and further objects and features of the invention will be apparent to those skilled in the art from the following detailed description of the annexed sheet of drawings which, by way of a preferred example only, illustrates one embodiment of the invention.

On the drawings:

Figure l isa longitudinal cross sectional view, with parts in elevation, of a hydraulic valve lifter according to this invention showing the position of the parts just prior to the valve opening operation.

Figure 2 is a view similar to Figure 1 but showing the positions of the parts as the valve is fully opened.

Figure 3 is a view similar to Figures 1 and 2 but illustrating the positions of the parts immediately following the valve opening operation.

As shown on the drawings:

The valve lifter 10 of this invention is slidably mounted in the engine block B and receives engine oil from a passageway P in the block. A cam C has the majority of the periphery thereof concentrically disposed about its axis to provide the base circle for the cam. A lobe L on the cam shaft raises the lifter l for reciprocating a push rod P. R. to open and permit closing of the valve (not shown) in the linkage.

The lifter includes a cylindrical hollow body II with a bottom Ila riding on the cam C and having a reduced diameter localized portion lib for receiving oil from the passageway P. A hole H0 is provided in this reduced diameter portion III) to supply engine oil to the interior of the body II.

The body has an internal groove l Id in spaced relation beneath the open top thereof and an internal shoulder He is provided beneath this groove. A guide [2 is mounted on the shoulder I la and held in place by a retainer ring l3 seated in the groove lid. The guide has a cylindrical bearing portion [2a in the center thereof slidably supporting the shank 14a of a needle valve H1. The valve It has a recessed head Mb receivin the lower end of the push rod P. R. The end of the valve shank Ma is preferably blunt with a beveled edge 140, but it can be conical or spherical to provide a tapered or converging active end face or seating face.

A plunger 45 is slidably mounted in the body I 1 between the guide 12 and the bottom shoulder [6a of a cavity [6 in the body of larger diameter than theportion slidably mounting the plunger. Since the body bore defining the cavity I6 is of larger diameter than the adjacent body bore slidably mounting the plunger IS, a shoulder is formed therebetween. This shoulder, as shown in the drawings, provides an edge which is adapted to scrape the plunger Wall as it moves therepast. As a result, the plunger wall will be scraped clean operation of the valve lifter. .A Well .I l is provided in the central portion of the bottom of the cavity l5 and contains a plunger spring l8. The plunger I5 is hollow and has a central cavity I500 freely receiving the valve shank Ma i9 is relatively heavy and is effective to take all slack out of the valve linkage.

Operation Engine oil is fed from the passageway P through the hole 1 la in the body H to fill the oil reservoir provided by the hollow cavity 15a in the'plunger id, as well as the chamber 16 and well ll and passageway I50. The plunger spring l8 holds the plunger firmly against the needle Valve and the needle valve spring 19 in turn takes up all slack in the valve train. Thus in the position shown in Figure l the needle valve is closed and all of the chambers beneath the guide l2 are filled with oil. Then as the cam rotates in the clockwise direction shown by the arrow to .move the lobe L against the bottom lid of the body, the lifter will raise the push rod P. R. .on a solid column of oil trapped below the plunger.

As the valve opening operation continues, some of the trapped oil will leak past the plunger into the reservoir lfia, thereby permitting the plunger to move downward into the chamber It as illustrated in Figure 2. This downward movement, of course, permits the needle valve 14 to drop with the plunger and the spring 19 will be compressed. The assembly will thereupon become shorter. However, as long as the needle valve is seated, the plunger cannot move upwardly in the body I I.

As illustrated in Figure 3, after the valve opening operation when the cam lobe has passed the bottom Ha of the body, the pressure on the trapped oil in cavity I'fi is relieved, the load on the compressed spring I3 is somewhat relieved, and the spring l9 will move the needle valve away from the plunger. As soon as this occurs, the passageway IE0 is opened up and the oil pressure in cavity 16 and reservoir lfia will be balanced. The plunger spring i8 is thereupon effective to move the plunger back into seating contact with the needle valve. At the same time, the cavity I6 is refilled with oil to replenish that lost by the leak down past the plunger in the valve opening operation. Since the engine maintains oil under pr ssure in p ag y P, this pressure 'is'efiective to expedite replenishment of oil into the cavity it, The pressure in the cavity lii ofzeourse, remains at a low value until the nextvalve opening operation. If any foreign matter lodges between the end Me of the needle valve and the orifice of the plunger, preventing full seating of the valve, the oil will not be trapped in the cavity 16 and on the next valve opening operation the plunger will crash down against the bottom Isa .to crush or dislodge this foreign matter. A substantial crushing force is obtained. This force may run as high :as several thousand pounds per square inch.

The smashing of any dirt that lodges on the valve seat by driving the plunger against the needle valve makes practical the use of an inexpensive needle valve construction in hydraulic tappets.

Inasmuch as the needle valve spring 19 is efieetive to take up all slack in the valve linkage, the lunger spring 48 can be relatively weak and this prevents vaporization of .oil in the cavity 1-6 due to fast plunger action which might otherwise create .a partial vacuum in the cavity. Thus, to prevent creation of a partial vacuum in the cavity, it is only necessary that the spring 18 will not exert a force on the plunger i5 which is greater than the .force exerted by atmospheric pressure on the op posite face .of the plunger, since the pressure in theoi-l reservoir compartment being vented by the hole '1 lo and passageway P, can never be less thanatmospheric.

After operation of a hot engine equipped with the lifters of this invention, some of the i r will come to rest eith r parti lly p or o p ely up on the cam lobe L. .In' extremely cold weather, the oil in the lifters will .congeal to a greater vis cosity, resisting flow. Prior to this vcongealing of the oil,,h owever, the lifters up on the cam lobe will have leaked down through flow past t p n er and when the cold engine is started the needle valves M- will be immediately forced by their springs Hi to take .up all slack in the linka es. This will open up the passageway 1.50 to a wide open condition thereby facilitating maximum flow of even heavily congealed oil. The lifters of this invention are therefore extremely efficient even when starting .a very cold engine.

The lifters of this invention can be produced at low cost. For example, if the plunger 1.51. made on a screw machine, a drill point finish will be sufficient for the orifice seat, and ,a form tool finish on the needle wi l eflici n lv coact wi h. a seat toprcvide c ncentric rings mak n anefiective seal. or course, the seal is also helped by the high unit pressure generated through line engagement between the plunger and the needle. The plunger and needle guide can also be made as a stamping with a punched hole in the plunger.

It should therefore be understood from the above descriptionsthat this invention provides a highly efficient, inexpensive hydraulic valve tappet or adjuster havinga needle valve controlling passage of a hydraulic fiuid in the operation of the adjuster.

It will be understood that modifications and variations may be effected without departing from the scope of the novel concepts of the present invention.

I claim as my invention:

1. A hydraulic adjuster comprising a hollow body, an orificed plunger slidable in said body, a thrust transmitting needle valve slidable in said body and having a converging active end portion seatable in the mouth of the orifice for controlling fiow through the orifice of the plunger, a first spring urging the mouth of the plunger orifice against the active end portion of the needle valve, and a second spring urging the needle valve away from the plunger, said second spring being stronger than the first spring and effective to expand the assembly and said first spring being efiectiveto urge the plunger against the needle valve for maintaining the assembly in expanded condition without creating a vacuum beneath theplunger.

2. A hydraulic valve lifter comprising a cylindrical cup shaped body having a closed bottom and an open top with an internal shoulder spaced inwardly from the top, a valve guide bottomed on the shoulder, a valve load transmitting needle valve having a shank portion slidably mounted in the guide, a spring urging said needle valve toward the open end of the body, an orificed plunger slidably mounted in the body, a second spring urging the plunger against the needle valve to close the orifice, said plunger separating the chamber in the body beneath the valve guide into two compartments, means for feeding oil into the compartment between the guide and the plunger, said needle valve being effective to trap oil in the other compartment for transmitting movement of the body to the needle valve, said second spring being relatively weak to prevent fast plunger action tending to create a partial vacuum in said other compartment, and said plunger having a free fit in said body to permit leak down of oil trapped in said other compartment to permit the assembly to be contracted.

.3..A hydraulic valve lifter comprising a cam actuated housing, aspring loaded valve operating thrust load transmittingneedle valve member slidably mounted in thehousing and efiective to take up slack in a valve train, said. needle valve member having a tapered end, a spring loaded plunger seat for said tapered end of the needle valve freely slidable in said housing, said needle valve and seat separating the housing into an oil inlet compartment and a load transmitting oil compartment joined freely through the seat when the needle valve is off the seat, the free sliding fit between the plunger and housing providing a leakage path between the compartments when the valve is on the seat, said path accommodating restricted flow of oil out of the load transmitting compartment when the lifter is loaded during a valve opening operation to shorten the eiTective height of the lifter through movement of the needle valve and seat toward the load transmitting compartment, said spring loaded needle valve extending the effective height of the lifter when said load is relieved after the valve opening operation thereby raising the Valve off its seat, and said spring loaded seat being effective to quickly seat against the valve as soon as oil pressures in the two compartments are equalized.

4. A hydraulic length compensating mechanism comprising a hollow body having a closed end, a passaged plunger slidably mounted in the closed end of the body and coacting therewith to trap hydraulic fluid in the bottom of the body, a valve slidably mounted in the body controlling flow through the passage of the plunger, a resilient biasing means in the body urging the valve away from the closed end of the body for increasing the operating length of the mechanism, and a relatively weak spring in the body acting on the plunger for urging the plunger against the valve with a force that is insufiicient to create subatmospheric pressures on the trapped hydraulic fluid in the body.

5. A hydraulic valve tappet comprising a hollow body, a passaged plunger slidable in the body adapted to trap fluid in the body to be supported thereon, a thrust load transmitting valve movable in the body controlling flow through the plunger passage, a take-up spring urging the valve in a direction to increase the effective length of the tappet, a weak spring urging the plunger against the valve, and an outturned scraping shoulder on the body surrounding the plunger and providing an edge acting on the plunger to clean off impurities.

6. In a hydraulic length compensating mechnism, a body provided with a longitudinal bore, said body being closed at one end and open at the other end, a piston reciprocable in the bore and defining in conjunction with said body a hydraulic compression chamber between one end thereof and the closed end of the body and a hydraulic supply chamber at its other end, said piston having a passage therethrough providing communication between the chambers, means admitting liquid into the body, resilient means biasing the piston away from the closed end of the body and having a maximum compressive strength less than the atmospheric pressure acting on the end of the piston adjacent the hydraulic supply chamber, a thrust load transmitting valve controlling the flow of liquid through the passage providing communication between the chambers, and resilient means biasing the valve away from said passage and controlling communication between the chambers.

7. In a hydraulic length compensating mechanism, a body provided with a longitudinal bore, said body being closed at one end and open at the other end, a piston slidable in the bore and defining in conjunction with said body a hydraulic compression chamber between one end thereof and the closed end of the body'and a hydraulic supply chamber at its other end, said piston having a passage therethrough providing communication between said chambersfmeans admitting liquid into the supply chamber, resilient means biasing the piston away :from the closed end of the body and having a maximum compressive strength less than the atmospheric pressure acting on the end of the piston adjacent the hydraulic supply chamber, a thrust load transmitting valve means movable in said housing and controlling the flow of liquid through the passage providing communication between the chambers, and spring means biasing said valve means away from saidpassage to increase the operating length of the mechanism whereby hydraulic fluid will flow into the hydraulic compression chamber until pressure conditions on opposite sides of the piston are in balance for permitting said resilient means to urge the piston against the valve means.

8. In a hydraulic takeup device, a housing having a closed end, a plunger slidable in the housing and adapted to rest on a body of fluid in the closed end of the housing, said plunger having a passage venting the closed end of the housing, a thrust load transmitting valve controlling flow through said passage, a first spring biasing the valve away from the passage to increase the operating length of the device, a second weaker spring urging the plunger toward the valve to close the passage, and a stop in the closed end of the housing for engaging the plunger to limit movement of the plunger toward said closed end of the housing whereby thrust load on the valve will cause the plunger to impact against the stop whenever extraneous matter prevents the valve from closing the passage and the extraneous matter will be subjected to the thrust load on the valve and be crushed or dislodged thereby permitting the valve to seat properly.

9. In a hydraulic takeup device of the type having telescoping thrust members with one of the members adapted to rest on a body of fluid contained in the other member, said one member having a passage venting the body of fluid, and a thrust load carrying valve controlling flow of fluid through said passage, the improvements which comprise a first spring acting on the valve for unseating the valve and for elongating the operating length of the device, and a second spring acting on the member resting on the body of fluid for urging said member against the valve to close the passage, said second spring being weaker than the first spring and having a maximum strength that is insufficient to create a sub-atmospheric pressure on said body of fluid.

10. In hydraulic take-up means, a cup, a piston slidable in the cup and adapted to abut a body of fluid contained in the cup under the piston therein, said piston having an aperture for passage of fluid to and from said body, a push rod for transmitting thrust to and from the piston and constituting a valve closin said aperture when in thrust transmitting relation with the piston, resilient means reacting against the cup and push rod respectively tending to urge the push rod outwardly of the cup, and other resilient means reacting against the cup and piston respectively tending to urge the piston outwardly of the cup, said other resilient means having a maximum compressive strength less than the pressure actin on the end of the piston opposite the end acted on by said other resilient means to prevent fast plunger action tending to create a vacuum on the fluid in the cup under the piston.

11. In a hydraulic tappet having a hollow cylindrical body with a closed lower end, a piston reciprocable within the body normally spaced a substantial operating distance from said closed lower end itO provide a liquid pressure chamber between the piston and said closed end and an upper liquid supply reservoir, said piston having a liquid passage connecting said chamber and reservoir with a valve seat, a valve coacting with said seat, a light spring in said pressure chamber acting normally to seat the valve seat and valve for closing the passage, a heavier spring arranged to elongate the tappet assembly and adapted to separate the valve and valve seat for opening the passage, and rigid stop means'at the lower closed end of the body to stop downward movement of the valve and piston when the piston is moved downwardly a sufllcient distance beyond its normal operating position thereby forcing said valve against its seat by positive mechanically applied pressure.

12. In a hydraulic tappet having a hollow body with a closed lower end, a piston reciproeable within said body normally spaced a substantial operating distance from said closed lower end to provide a liquid pressure chamber between the piston and closed end and an upper liquid supply reservoir, said piston having a liquid passage connecting said chamber and reservoir with a valve seat at the upper end of said passage, a valve above said piston adapted to engage downwardly against said valve seat, a light spring in said pressure chamber acting on said piston normally to move the piston into closed position against said valve, a heavier spring arranged to urge said valve in an upward direction to elongate the assembly, and a rigid stop means in said chamber against which the piston is adapted to directly engage when moved downwardly a sufficient distance beyond its normal operating position thereby forcing the valve against its seat to crush extraneous matter therebetween.

13. In a hydraulic tappet having a hollow body with a closed lower end, a piston reciprocable within the body normally spaced from said closed lower end to provide a liquid pressure chamber between the piston and said closed end and an upper liquid supply reservoir, said piston having a liquid passage connecting said chamber and reservoir with a valve seat, a valve coacting with said seat, a light spring in said pressure chamber acting normally to seat the valve seat and valve for closing the passage, a heavier spring arranged to elongate the tappet assembly and adapted to effect separation of the valve and valve seat for opening the passage, and said lower closed end of the body having an abutment wall stoppin downward movement of the valve and piston when the piston is moved downwardly a suflicient distance beyond its normal operating position in the body thereby forcing the valve against its seat by positive mechanically applied pressure.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date Re. 21,931 Voorhies et a1 Oct. 21, 1941 2,109,816 Best Mar. 1, 1938 2,140,826 Bettison Dec 20, 1938 2,160,257 Appel May 30, 1939

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