VALVE SYSTEM WITH HYDRAULIC POWER TRANSMISSION

Abstract: A valve system for gas or liquid, comprising a hydraulic power transmission (19) where the pressure of hydraulic fluid is controlled by fluid pressure actuated members (15) and the changes of the fluid pressure actuate operative members (5, 7, 10) of the valve system, where the fluid pressure actuated members and the operative members comprise a tubular expandable bellows (10, 14, 25) with one gable (21) closed and the other (22) connected via tubes (11, 23) or similar to other expandable bellows (10, 14, 25) in the valve system and the thus arisen closed space is filled with hydraulic fluid (24), and that the expandable bellows (10) in the operative member stand in connection with a valve body (5) in a valve tube (1) and that the fluid pressure actuated members (15) is placed outside the valve tube (1). The valve body (5) is movable in the longitudinal direction of the valve tube (1) and in close contact with a seat (3) when the valve system is closed.

Description: VALVE SYSTEM WITH HYDRAULIC POWER TRANSMISSION The present invention relates to a valve system equipped with closed device for hydraulic power transmission, where the pressure of a closed hydraulic fluid is controlled at one or more points assisted by fluid pressure actuated members and the changes of the fluid pressure actuate one or more operative members of the control system. The invention is for example intended for control and shut-off valves in pipings and also for a so- called excess flow valve for automatic closing of a tube or a fluid for example in a position where the pipe has ruptured so that the contents can stream out into the environment and cause damage. The invention is particularly applicable at power transmission through walls which separate for example a gas and a fluid from the environment. TECHNICAL BACKGROUND Control valves and shut-off valves are generally provided with a control device in the form of a hand control, which is mounted directly on the valve spindle. A device for remote control operation can be entirely mechanical and for example, be formed of one or more shafts, which are connected to the valve spindle via a cardan joint or be electronic and be formed of an electric motor, which via a gear reduction is connected to the valve spindle, and the motor is controlled, for example, by electrical signals which, via a relay closes the current to the motor. The remote control is actuated for example by the valve being located in a place which cannot be reached without great difficulty inter alia on pipes, located high above the ground and in closed spaces, as for example cisterns. It has also proven difficult to arrange remote controls with lead-ins in for example cisterns in which a fluid or a gas is under pressure and also on long distances where many moving direction of the transmission are demanded. Quick closing valves to a certain extent have an outstanding position in the applications, where the present invention is advantageous. Quick closing can either be done manually or automatically, e.g. when damage has occured and it is desired to immediately stop the gas or liquid flow. A complete mechanical excess flow valve is described in Swedish Patent 7413120 and comprises a valve body on a valve push rod mounted in a tube and movable in the EA longitudinal direction of the tube towards a ring-shaped seat. The push rod is in connection with a spring on the outside of the tube via a link mechanism, where one of the link arms extends through the wall of the tube via a sealing box. When there is a pipe rupture at a point downstream of the excess flow valves in the flow direction, the flow rate in the tube increases and a low pressure arises on the underside of the valve body. When the low pressure causes a force on the valve body, which via the link mechanism comprises the spring, the valve body is displaced towards the seat, and the tube is closed. The size of .the spring force is adjustable and thus the excess flow valve can be closed at different flow rates. A disadvantage with the conventional excess flow valve is that the tightening box in the tube wall as time goes becomes worn and begins to leak. Another disadvantage is that there is no easy way to change the adjustment in the valve using remote control. A further disadvantage is that the valve cannot be opened without great difficulty if it has been closed by mistake. Then the pressure in front of the valve has to be lowered, e.g. by using a special unloading valve before the excess flow valve can be opened again. In the same way another conventional excess flow valve works, which is not adjustable from the outside of the tube but is equipped with a spring, which directly works on the valve body inside the tube. SUMMARY It has now surprisingly been proven that it is possible to bring about a closed hydraulic power transmission in which there is no risk for leakage and wear by using tubular, expandable bellows, which the fluid pressure actuated members of the valve system and that then pressure changes of the closed hydraulic fluid actuate one or more operative members. The invention is described in the following sections in the performance example and claims by way of the accompanying drawings, in which:- Figure 1 is a longitudinal section through an excess flow valve Figure 2 is a remote control device to the excess flow according to Figure 1. Figure 3 is an outline of the hydraulic power transmission BUKtA- CLOSER DESCRIPTION OF THE INVENTION Referring to Figure 3, the hydraulic power transmission device 19, comprises two or more tubular, expanding bellows 20, which at one end, the gable 22, are closed and at the other gable 21, are connected to each other by tubes 23, or hoses. The closed space is filled with a hydraulic fluid 24. The bellows 20, are manufactured for example of metal or rubber and the connecting tubes 23, or hoses should be made of materials, which do not change appreciable in volume, when the pressure rises in the device. By pressing the bellows 20, in axial direction, the volume thereof is decreased. This causes some or all the other bellows 20, in the hydraulic power transmission 19, to be extended to obtain the corresponding volume. The extension takes place in the axial direction which then affects other operative members in the valve system. A condition for good operation is that the bellows 20, are operated in radial direction so that the movement of the bellows 20, are concentrated in the axial direction. Therefore a guide bushing 25, is usually disposed around the bellows 20, in which the bellows 20, are movable axially. EXAMPLE Referring to Figure 1, the excess flow valve comprises a cylindrical valve tube 1, having two end flanges 2, by which the valve can be connected to a table system having substantially the same tube dimensions as the tube 1. A conical seat 3, is mounted at the one end of the valve tube 1, and extends around the inside of the valve tube 1. A conical valve body 5, adapted to fit against the seat 3, by the tightening ring 6, is mounted at the one end of a push bar 7, which is axially adjustable in a steering 4, attached on the seat 3, supported by fins 9. The push rod 7, at its other end is fixedly attached to expansion bellows 10, made of steel as per the invention and having a steering guide bushing 8, which surrounds the expansion bellows 10, and in which the expansion bellows 10, are axially movable. The other end of the expansion bellows 10, are fixedly attached on a pressure tube 11, which extends from the guide bushing 8, via a tube bend out through the wall of the valve tube 1, to which the pressure tube 11, is welded. The guide bushing 8, also surrounds a part of the pressure tube 11, and is adjustable along the pressure tube 11, which in its_ 4 turn is fixedly supported by a fastening device 12, which extends from the pressure tube 11, to the inner surface of the valve tube 1, through which axial forces in the pressure tube 11, are taken up when there is movement in the expansion bellows 10. The pressure tube 11, 5 is via a reinforced hose 13, in connection with a pressure bellows 14, as per the invention outside the valve tube 1. The pressure bellows 14, is connected with a spring control device comprising a pressure limitation device 15, as shown in Figure 2, which can compress the pressure bellows 14, more or less. The 10 pressure of the pressure tube 11, can be read on a manometer 18, which is in connection with this via a manometer tube 16. The manometer tube 16, may be closed by a shut-off valve 17. The excess flow valve is adjusted so that it closes at a certain flow rate of the valve tube 1, by adjusting a corresponding pressure 5 on the manometer 18, by using the pressure limitation device 15. If the flow rate should increase in the valve tube 1, for example after a tube rupture, an increasing depression occurs at the rear of the valve body 5, seen from the flow direction, as shown by an arrow on Figure 2. The pressure on the valve body 5, in direction towards the 20 expansion bellows 10, increases and the power in the . push rod 7, compresses the expansion bellows 10, so that the valve body 5, moves towards the seat 3, to effect closure. When the pipe rupture is repaired, the valve body 5, can again be influenced to open using the pressure limitation device 15. 25 when having varying the flow rate in the valve tube 1, the manometer 15, shows a varying pressure in the pressure tube 11. The reading on the manometer scale 15, will thereby be proportional to the flow rate in the valve tube 1. The manometer 15, can be graduated in flow rate magnitudes. In an alternative embodiment of the invention, 30 the manometer 15, can be connected to a registered member which integrates the flow in time and thus the excess flow valve also serves as a flow meter. The pressure limitation device 15, includes in the example an air-operated membrane and thus this device can also be remotely ^ controlled. At a quick cut-off air pressure is arranged on the side of the membrane, which provides for a compression of the pressure limitation spring in the pressure limitation device 15, while the air. pressure is arranged on the opposite side of the membrane at the opening of the valve. -BUREA OMPI

Claims: CLAIMS 1. A valve system for gas or liquid c h a r a c t e r i z e d by the fact that a hydraulic power transmission (19) where the pressure of hydraulic fluid is controlled by fluid pressure actuated members (15) and the changes of the fluid pressure actuate operative members (5, 7, 10) of the valve system, where the fluid pressure actuated members and the operative members comprise a tubular expandable bellows (10, 14, 25) with the one gable (21) closed and the other (22) connected via tubes (11, 23) or similar to other expandable bellows (10, 14, 25) in the valve system and the thus arisen closed space is filled with hydraulic fluid (24), and that the expandable bellows (10) in the operative member stand in connection with a valve body (5) in a valve tube (1) and that the fluid pressure actuated members (15) is placed outside the valve tube (1). 2. A valve system according to claim 1 c h a r a c t e r i z e d by the fact that the valve body (5) is movable in the longitudinal direction of the valve tube (1) and in close contact with a seat (3) when the valve system is closed. 3. A valve system according to claim 2 c h a r a c t e r i z e d by the fact that the expandable bellows (10) in the operative member at its one end is connected to a push rod (7) on which a valve body is mounted. 4. A valve body according to claim 3 c h a r a c t e r z e d by the fact that the push rod (7) is provided with a tubular guide bushing (8) which surrounds the expandable bellows (10). 5. A valve system according to claim 1 - 4 c h a r a c t e r ! ' z e d by the fact that a valve system is provided of a control or shut-off valve. 6. A valve system according to claim 1 - 4 c h a r a c t e r i z e d by the fact that it is provided of a quick closing valve. OMPI

Inventors: LINDGREN NILS ERIK, LINDGREN, NILS, ERIK
Applicants: SSAB SVENSKT STAL AB, SSAB SVENSKT STAOL AB
Application year: 1984
Main classification: F15B15
IPC codes: B60T11, F15B7, F15B15, F16K31