US3329154A - Compressor control valve - Google Patents

Abstract

1,043,806. Valves. BENDIX-WESTING- HOUSE AUTOMOTIVE AIR BRAKE CO. March 20, 1964 [March 26, 1963], No. 11963/64. Heading F2V. [Also in Division G3] A valve suitable for insertion in the line between a compressor and a receiver comprises an inlet chamber 12, a delivery chamber 14 and a check valve 60 allowing flow from the inlet to the delivery chamber. The check valve forms part of a piston 46 slidable in bore 47 and co-operating with a stop 48 carried by a spindle 42. The latter also carries an exhaust valve 36 loaded by a spring 54. When the pressure in the inlet chamber reaches a predetermined value it unseats the exhaust valve with a snap-action and the lowered pressure in the inlet chamber then allows the piston 60 to be driven downwardly by the receiver pressure until it engages stop 48, whereby the exhaust valve is retained open until the receiver pressure drops to a second, lower, predetermined value. In modifications, the piston and exhaust valve are rigidly interconnected, or the spindle 42 is rigid with the piston and the exhaust valve is slidable on the spindle with its loading spring in exhaust chamber 35. A filter may be provided in the inlet chamber upstream of the check valve. The latter comprises an annular gasket supported on a plate 64 retained by a snap-ring 66.

Description

July 4, 1967 MORSE ETAL 3,329,154

COMPRESSOR CONTROL VALVE Filed March 26, 1963 INVENTOR ROBERT 'J. MORSE HARRY M. VALENTINE ATTQRNEYS United States PatcntOfiFicc 3,329,154 Patented July 4, 1967 3,329,154 COMPRESSOR CONTROL VALVE Robert J. Morse and Harry M. Valentine, Elyria, Ohio, assignors to Bendix-Westinghouse Automotive Air Brake Company, Cleveland, Ohio, a corporation of Delaware Filed Mar. 26, 1963, Ser. No. 267,986 2 Claims. (Cl. 137-116) This invention relates to fluid pressure responsive valves and more particularly to a valve for automatically controlling the delivery or discharge side of an air compressor.

The object of the present invention is to provide a novel valve responsive to the delivery pressure of an air compressor and adapted to be interposed between the delivery side of an air compressor and a fluid pressure receiver or reservoir to serve the combined functions of a governor, discharge line unloader, check valve, drain valve and safety valve.

The invention is hereinafter described in detail in conjunction with the single, partly schematic drawing which includes a vertical cross sectional view of a valve embodying the features of the invention.

Referring now to the drawing, the valve of the invention comprising a casing having inlet and delivery cavities 12, 14 provided with inlet and delivery ports 16, 18 respectively connected to the discharge line 20 of a compressor 22 and to a delivery line 24 connected to a fluid reservoir 26.

The casing 10 is composed of an upper part 28 and a lower part 30 which is threadingly connected to the upper part as shown and includes an annular shoulder 32 surrounding an exhaust port 34 leading into an atmospheric cavity 35 and normally closed by a spherical valve member 36 which sealingly engages a conical valve seat 38 on the outer or downstream side of the exhaust port 34. The valve 36 is provided with a central bore 40 receiving the lower threaded end of a plunger 42 which extends upwardly through the inlet cavity 12 and is slidingly received at its upper end in a bore 44 drilled in the lower end of a piston like member 46 slidingly received in an upper reduced diameter part 47 in casing member 28 and hereinafter described in detail. The plunger 42 carries adjacent its upper end an abutment member 48, which may be a nut as shown or other suitable collar, having upper and lower surfaces 50, 52. Interposed below the lower surface 52 of the abutment 48 and the shoulder 32, surrounding the exhaust opening 34, is a regulating spring 54 which serves to urge the valve 36 at all times to its closed position.

Referring now to the piston member 46, this may be of elongated, cylindrical construction having a lower end 56 adapted to engage the upper surface 50 of the abutment 48 when the member 46 is moved downwardly in a manner which will become apparent. The member 46 may be provided with an integral annular collar 58 whose lower surface provides the upper support for the flat inner part of a cup gasket 60 having a sealing flange 62 extending in the direction of the delivery cavity 14. The lower side of the gasket 60' is supported by an annular ring 64 retained in place by a snap ring 66 received in a groove about the member 46 as shown. The cup gasket 60 is constructed and arranged as a check valve to permit fluid under pressure to flow past the periphery of the sealing flange 62 from the inlet 12 to the delivery 14 cavities but prevents fluid flow in the reverse direction.

In operation, assuming that there is initially no pressure in the reservoir 26 when the compressor 22 is operated fluid flows by way of the discharge line 20 through the inlet port 16 into the inlet cavity 12 and thence past the sealing flange 62 into the inlet cavity 14 and from there to the reservoir 26 by way of port 18 and conduit 24. As the compressor continues to operate, pressure builds up throughout the entire system and acts downwardly on the exhaust valve 36 through the exhaust port 34. The effective area of the exhaust valve is a function of the diameter of the exhaust port and when system pressure acting on this elfective area exceeds the upward or closing force of the spring 54, the valve 36 is forced off the seat 38 thereby exposing the entire cross sectional area of the valve to system pressure so that it is driven to its fully open position with a snap action. Upon this occurrence, all of the pressure existing in the inlet cavity 12 is exhausted to atmosphere with the result that the pressure in the reservoir 26 acts in a reverse direction through the conduit 24 and delivery port 18 onto the upper side of the cup gasket 62 to spread the sealing flange into sealing engagement with the side wall of the delivery cavity 14 and at the same time exerts a down- Ward force on the cylinder member 46 which at this stage is unopposed by pressure in the inlet cavity 12, this being now substantially at atmospheric pressure due to the open condition of the valve 36-. The piston member 46 descends until the lower edge 56 of the piston member engages the upper surface 50 of the abutment 48 thus preventing the valve member 36 from being returned by the spring 54 to its closed position so long as the downward pressure force acting on the upper surface of the piston member and cup gasket exceeds the upward force of the spring 54.

With the valve 36 in its fully open position and retained in this position by the above described action of the piston member 46, it will be apparent that thecompressor is effectively unloaded and delivers its entire output directly to atmosphere through the open exhaust port 34. It should also be apparent that any liquid which might have accumulated in the discharge line 20 or in the inlet cavity 12 is also discharged to atmosphere through the exhaust port 34.

Assume now that the pressure in the reservoir 26 starts to fall and continues to fall until it reaches a level Where the downward force acting on the piston member 46 is less than the upward force of the spring 54 acting on the piston 46 through the abutment member 48. At this stage the parts of the valve commence moving toward their upper position of the drawing and continue to move in this direction until the valve 36 engages the conical seat 38 thereby closing the exhaust port. Immediately upon this occurrence pressure builds up in the inlet cavity 12 and acts on the underside of the piston member 46 to drive this to its fully raised position of the drawing with a snap action. Thereafter fluid flows past the periphery of the gasket 60 to the reservoir 26 as previously described until the pressure in the system again rises to a level suflicient to unseat the exhaust valve 36 where upon the above described cycle of operation is repeated.

A particularly desirable feature of the valve of the present invention is that the exhaust valve is movable between its open and closed positions independently of the piston 46, such independent movement being afforded by the sliding of the piston bore 44 with respect to the upper end of the plunger 42. With this arrangement, it should be apparent that should the piston member, for whatever reason, stick to the casing, the valve 36 will nevertheless move to its open position when the system pressure reaches a predetermined high value established by the spring 54 and thus serves as a safety valve to prevent the build up of system pressure above a safe level.

Not only does the valve of the invention operate as an unloader and a liquid discharge valve, as well as a check and safety valve, but by selective correlation of the eifective motive areas, the valve serves as an efficient compressor governor; that is to say, with proper selection of motive areas the pressure at which the valve opens may be significantly different from the pressure at which the valve closes, For example, in order for the valve to remain open until reservoir pressure has fallen to a level substantially below the pressure at which the valve was opened the effective cross sectional area defined by the diameter of the cup gasket or the reduced diameter part 47 is made larger than the diameter of the exhaust port 34. It will thus be apparent, that a high pressure acting on the effective area of the exhaust valve sufficient to compress the spring 54, and open the valve 36, will be balanced by a lower reservoir pressure acting across the greater effective area on the upper side of the cup gasket and piston member 46. An additional factor insuring a lower closing pressure is the friction force between the lip or flange 62 of the cup gasket 60 and the wall of the upper part 47 of the casing after the lip 62 has been moved into sealing engagement with the wall by reservoir pressure upon opening of the exhaust valve.

It will be apparent to those skilled in the art that the embodiment of the invention shown and described is illustrative only. For example, though it is desirable that there be independent or lost motion cooperation between the piston member 46 and the exhaust valve 36 in order that the exhaust valve can serve additionally as a safety valve as explained above, this arrangement is not essential inasmuch as the valve will operate effectively if the piston and exhaust valve are rigidly interconnected, and in certain environments this arrangement might be preferable. Other modifications are: an arrangement where the plunger 42 is rigid with the piston 46 and the exhaust valve is slidable with respect to the plunger; the location of the spring 54 in the atmospheric cavity 35; and the inclusion of a filter in the valve casing between the inlet port 16 and the cup gasket 60. The foregoing modifications and a variety of others may be resorted to without, however, departing from the scope and spirit of the appended claims.

What is claimed is:

1. A fluid pressure control valve comprising a casing,

a fluid pressure responsive element dividing the interior of said casing into separate inlet and delivery cavities, inlet and delivery ports respectively connected to said cavities, an exhaust port connected to said inlet cavity, a check valve carried by said pressure responsive element for permitting the one-way How of fluid from said inlet to said delivery cavity but not in the reverse direction, said check valve forming a part of said pressure responsive element and slidably engaging the interior wall of said casing, an exhaust valve for controlling said exhaust port and having an effective area responsive to the pressure in said inlet cavity for moving said valve to its open position independently of said element, resilient means urging said exhaust valve at all time towards its closed position, and plunger means including a lost motion connection interconnecting said exhaust valve and said fluid pressure responsive element to retain said exhaust valve open only after movement thereof to its open position in response to pressure in the inlet cavity and upon movement of the pressure responsive element towards said exhaust valve to take up said lost motion connection, in response to pressure trapped in the delivery cavity by closing of said check valve upon opening of said exhaust valve.

2. The control valve of claim 1 wherein the efiective area of said exhaust valve is less than the efiective areas of said pressure responsive element exposed respectively to said inlet and delivery cavities.

References Cited UNITED STATES PATENTS 2,395,941 3/1946 Rockwell l37l15 X 2,855,944 10/1958 Albin 137l02 2,952,267 9/1960 Reis 137l15 WILLIAM F. ODEA, Primary Examiner.

ISADOR WEIL, Examiner.

D. H. LAMBERT, Assistant Examiner.

Claims (1)

1. A FLUID PRESSURE CONTROL VALVE COMPRISING A CASING, A FLUID PRESSURE RESPONSIVE ELEMENT DIVIDING THE INTERIOR OF SAID CASING INTO SEPARATE INLET AND DELIVERY CAVITIES, INLET AND DELIVERY PORTS RESPECTIVELY CONNECTED TO SAID CAVITIES, AN EXHAUST PORT CONNECTED TO SAID INLET CAVITY, A CHECK VALVE CARRIED BY SAID PRESSURE RESPONSIVE ELEMENT FOR PERMITTING THE ONE-WAY FLOW OF FLUID FROM SAID INLET TO SAID DELIVERY CAVITY BUT NOT IN THE REVERSE DIRECTION, SAID CHECK VALVE FORMING A PART OF SAID PRESSURE RESPONSIVE ELEMENT AND SLIDABLY ENGAGING THE INTERIOR WALL OF SAID CASING, AN EXHAUST VALVE FOR CONTROLLING SAID EXHAUST PORT AND HAVING AN EFFECTIVE AREA RESPONSIVE TO THE PRESSURE IN SAID INLET CAVITY FOR MOVING SAID VALVE TO ITS OPEN POSITION INDEPENDENTLY OF SAID ELEMENT, RESILIENT MEANS URGING SAID EXHAUST VALVE AT ALL TIME TOWARDS ITS CLOSED POSITION, AND PLUNGER MEANS INCLUDING A LOST MOTION CONNECTION INTERCONNECTING SAID EXHAUST VALVE AND SAID FLUID PRESSURE RESPONSIVE ELEMENT TO RETAIN SAID EXHAUST VALVE OPEN ONLY AFTER MOVEMENT THEREOF TO ITS OPEN POSITION IN

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