Block and bleed valve assembly

A three-way valve includes a rotatable shaft positioned within a cylindrical, linear bore within a housing. A fluid pressure source is coupled via an input port to an inner end of the bore which includes a valve chamber. An output port coupled to a pressure-operated device is also disposed in the housing and is connected to the valve chamber, as is a drain port. Attached to the shaft's inner end is a first seal, while a second seal is attached to the shaft in closely spaced relation to the first seal. Rotational displacement of the shaft clockwise causes the first seal to seal off the source of fluid pressure from the valve chamber, while allowing for fluid discharge through the drain port. Rotational displacement of the shaft in a second, opposed direction connects the pressure-operated device to the pressure source via valve chamber and isolates valve chamber from drain port.

FIELD OF THE INVENTION

This invention relates generally to pneumatic and hydraulic valves and is particularly directed to a three-way, soft seal valve having a single moving part which may be either machine- or manually-operated.

BACKGROUND OF THE INVENTION

Three-way valves have long been used for controlling fluid flow in various types of pneumatic and hydraulic systems over a wide range of applications. In some of these valve assemblies, the valve member is in the form of a ball which is free to move between a pair of valve seats and an actuating pin for urging the ball against one of the two valve seats. This type of ball valve suffers from several limitations, including not being sufficiently precise to control the flow of fluid. In addition, the ball member may occasionally tend to impede the full flow of fluid through a side port when the ball is disposed intermediate the two valve seats.

One type of three-way valve is the block and bleed valve for controlling fluid communication between a pressure source and at least two valves activated by the pressure source. These types of valves are frequently used for controlling fluid flow between a pressure source, a pilot valve, and a safety valve. These types of valves generally include a diaphragm, or partition, disposed between different chamber portions of the valve which operate at different pressures during certain phases of the functioning of the valve. The diaphragm is subject to deterioration which interferes with valve operation and requires frequent replacement. These types of valves also include two separate valves in a manifold: one valve to control access to the source of pressure, and the other valve to allow for draining, or bleed off, of the fluid under pressure. Because these types of valves actually include two inter-dependent valves, they are assembled from many components, require complicated connection schemes, and are subject to error by operating the wrong valve, or only one valve.

The present invention avoids these limitations of the prior art by providing a block and bleed valve assembly having a single movable member, operated by hand or by machine, which is easily and quickly displaced between first and second positions for respectively isolating and connecting a pressure-operated device and a source of either pneumatic or hydraulic pressure. A “soft”, leak-free seal is provided for isolating the source of pressure from the pressure-operated device and the fluid drain, or bleed.

OBJECTS AND SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide a three-way pneumatic or hydraulic valve in a pressurized system for isolating a device such as a gauge or tool from a pressure power source for calibration, repair, servicing, removal or replacement of the device.

It is another object of the present invention to provide a pressure valve having a single moving part which is capable of simultaneously blocking and bleeding pressure in a closed vessel or system.

A further object of the present invention is to provide in a pressurized system a single machine- or manually-operated valve having a minimum number of moving parts which allows for the servicing or replacement of critical components without shutting down the system.

A still further object of the present invention is to provide a three-way valve for a hydraulic or pneumatic system which when moved between its open and closed positions restricts the flow of pressure medium to prevent internal system disturbance and to minimize leakage.

The present invention contemplates a block and bleed valve assembly comprising a housing coupled to a source of fluid under pressure, to a fluid pressure operated device, and to a fluid drain. The valve further comprises a chamber disposed in the housing and coupled to the source of fluid, to the fluid pressure operating device, and to the fluid drain. A seal member is disposed within the valve chamber and is movable between first and second positions. In the first position of the seal member, the source of fluid is isolated from the valve chamber and fluid within the valve chamber is discharged through the fluid drain. In the second position of the seal member, the fluid under pressure is provided to the fluid pressure operated device and the fluid is prevented from discharging from the valve chamber via the drain. The three-way valve further includes a remote controlled means coupled to the seal member for moving the seal member between the first and second positions for closing and opening the valve.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring toFIG. 1, there is shown a lateral sectional view of a block and bleed valve assembly10in accordance with the principles of the present invention. The inventive block and bleed assembly10includes a valve housing12having an inlet, or supply, port14, an output, or use, port16, and a drain passageway18. Inlet port14, outlet port16and drain passageway18are all connected to an elongated, generally linear bore, or slot,68having a circular cross section which decreases in diameter in proceeding inward into housing12. Disposed within bore68is the combination of an outer valve liner sleeve22and an inner stem24. A lateral sectional view of the combination of the outer valve liner sleeve22and inner valve stem24is shown inFIGS. 2, 3 and 4which are described in detail below. A partially exploded side elevation view of stem24is shown inFIG. 9. A lateral section view of valve linear sleeve22is shown inFIG. 10. A lateral sectional view of bore, or inner slot,68within the valve assembly housing is shown inFIG. 11. The valve housing12, valve liner sleeve22and valve stem24are all comprised of a hard, high strength material such as steel.

In inner end of bore68and valve housing12is defined by a generally cylindrically shaped valve chamber27. Disposed within valve housing12and extending through one of its lateral walls is the aforementioned inlet port14. Disposed within valve housing12and extending through its upper surface is the aforementioned outlet port16. Finally, disposed within valve housing12and extending through its lower surface and in communication with bore68is the aforementioned drain, or bleed, passageway18. Inlet port14is connected to a first end of valve chamber27by means of an inlet passageway17, while output port16is connected to a lateral portion of valve chamber27by means of a device passageway31. Connected to and in communication with inlet port14is a source of fluid under pressure15. The pressure may be either pneumatic (gas) or hydraulic (liquid). Attached to output port16is a pressure operated device20which is responsive to either pneumatic or hydraulic pressure. Pressure operated device20is typically either a gauge or a tool. The block and bleed valve assembly10of the present invention is usable with virtually any type of source of fluid under pressure15and pressure operated device20.

As shown inFIG. 11, disposed on the inner surface of bore68adjacent its outer end is a threaded portion70. As shown inFIG. 10, disposed on the outer surface of valve liner sleeve22is a corresponding threaded portion64. Threaded portions64and70are adapted for mutual engagement when valve liner22is inserted in bore68so as to form interfitting threads28of the valve assembly housing12and the valve liner sleeve as shown inFIG. 1. Provided on the outer surface of valve liner sleeve22are first and second spaced annular recesses46and48. Respectively disposed within the first and second annular recesses46,48are first and second outer gaskets, or cartridge seals,32and34. The first and second outer gaskets32,34are also in contact with the inner surface of bore68to form a leak-proof seal between valve housing12and valve liner sleeve22as shown inFIG. 1.

Valve stem24includes an elongated, generally cylindrical shaft50having a threaded portion50aextending along a portion of its length. Threaded portion50aof shaft50is adapted for mutual engagement with a corresponding threaded portion22aon a inner portion of valve liner sleeve22. Interfitting threaded portions22aand50aare shown as a single element29inFIG. 1and allow for linear displacement of stem24in the directions of arrow30inFIG. 1. Rotation of stem24in a first direction causes an inward displacement of the stem into valve housing12, while rotation of the stem in a second, opposite direction allows for outward movement of the stem in the valve housing. To facilitate rotational displacement of stem24, a manual control knob26is attached to the outer end of stem by means of the combination of a coupling pin74and aperture76. While capable of manual operation, valve stem24may also be coupled to and operated by a machine, or rotary drive, as shown in dotted line form as element72inFIGS. 2, 3 and 4. The use of machine72for positioning valve stem24within valve housing12could provide automatic operation of the block and bleed valve assembly10in accordance with one aspect of this invention. An inner gasket36is positioned within an annular recess52on the outer surface of elongated shaft50as shown inFIG. 1. Inner gasket, or cartridge seal,36disposed in annular recess52is also in intimate contact with bore68in valve housing12to provide a fluid seal between valve stem24and the valve housing. Gaskets32,34and36are preferably comprised of a high strength, pliable somewhat compressible material such as rubber or a synthetic polymer.

Disposed on the inner end of shaft50is another apertured coupler60b. Apertured coupler60bis adapted for coupling to another apertured coupler62disposed in a mounting member25. Mounting member25may be securely attached to the inner end of shaft50by inserting a coupling pin through the aligned apertures of apertured couplers60band62. Securely attached to opposed ends of mounting member25are first and second seals38and40. Each of first and second seals38,40is comprised of a compressible sealing material such as rubber or a synthetic polymer. First and second seals38,20are securely attached to opposed ends of mounting member25by conventional means such as an adhesive or a mechanical coupler which is not shown in the figures for simplicity.

The block and bleed valve assembly10operates in the following manner. When stem24is rotated in a clockwise direction when viewed along the length of the stem from its outer to its inner end, the stem is moved in a leftward direction, or into the valve housing12, as viewed inFIG. 1. This leftward direction is shown by arrows54and56respectively inFIGS. 5 and 6which show the positions of the first and second seals38and40when the block and bleed valve assembly is closed, or sealed. Stem24is linearly displaced by this rotation so that the first seal38attached to the stem's inner end engages a first sealing surface, or valve seat,42disposed at the juncture of inlet passageway17and valve chamber27. With seal38an intimate contact with first sealing surface42, fluid under pressure from fluid source15is prevented from entering valve chamber27and reaching the pressure operated device20. This closed position of first seal38in valve chamber27is shown inFIGS. 1 and 2. When stem24is rotated in a counter clockwise direction when viewed from its outer end, first seal38is displaced away from first sealing surface42and second seal40is moved toward second sealing surface44. To assume this position, valve stem24is moved in the direction of arrows58and59shown respectively inFIGS. 7 and 8. When the block and bleed valve assembly10is fully opened, first seal38is displaced from first sealing surface42allowing fluid under pressure to enter valve chamber27and pass to the pressure operated device20, and second seal40is in intimate contact with second sealing surface44preventing fluid from being discharged from valve chamber27via drain passageway18. The first and second sealing surfaces43,44are inwardly tapered in proceeding toward an adjacent end of the valve chamber27to provide a high pressure seal when the block and bleed valve assembly is opened or closed.

Valve stem24is thus movable between the fully closed position shown inFIG. 2, where fluid is prevented from flowing to the pressure operated device20and the fluid can be bled from the valve chamber27, and the fully opened position shown inFIG. 4where fluid is allowed to pass from the fluid source15to the pressure operated device, but is prevented from draining from the valve chamber27. In between these two positions, valve stem24passes through a continuum of intermediate positions, one of which is shown inFIG. 3. In these intermediate positions, the first seal38is not in contact with the first sealing surface42and the second seal40is not in contact with the second sealing surface44. The outer diameter of the generally cylindrical mounting member25is less than the inner diameter of the valve chamber27to permit fluid under pressure to pass within the valve chamber27around the outer periphery of mounting member to the pressure operated device20as well as to drain passageway18. Thus, during valve opening and closing, fluid is provided under pressure to the pressure operated device20as well as to drain passageway18. The spacing between mounting member25and valve chamber27may be selected in accordance with the application in which the block and bleed valve assembly10is used. For example, when more frequent interruption in operation of the fluid pressure system is called for, a larger gap between adjacent portions of mounting member25and valve chamber27of on the order of 0.010 inch may be called for to facilitate closure and bleeding of the valve. On the other hand, where operating interruptions are less frequent and a lower bleed rate is desired, a smaller gap between adjacent portions of mounting member25and valve chamber27such as on the order of 0.0025 inch may be called for. In a preferred embodiment, the spacing between the outer surface of mounting member25and valve chamber27is selected to restrict fluid flow during valve opening and closing so as to avoid internal fluid system disturbance and leakage.

While particular embodiments of the present invention have been shown and described, it will be obvious to those skilled in the relevant arts that changes and modifications may be made without departing from the invention in its broader aspects. Therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of the invention. The matter set forth in the foregoing description and accompanying drawings is offered by way of illustration only and not as a limitation. The actual scope of the invention is intended to be defined in the following claims when viewed in their proper perspective based on the prior art.