GB2226429A

GB2226429A - Valves

Info

Publication number: GB2226429A
Application number: GB8923850A
Authority: GB
Inventors: David Kenneth Durrant
Original assignee: Individual
Current assignee: Individual
Priority date: 1988-10-25
Filing date: 1989-10-23
Publication date: 1990-06-27
Anticipated expiration: 2009-10-23
Also published as: GB2226429B; GB8923850D0

Abstract

A fluid flow control valve has its actuating force provided by the fluid supply pressure of the fluid flowing into the valve. The actuation of the valve is by the differential force acting on opposite sides of a valve member (7) which moves relatively to a valve seating (12) to control the fluid flow. The valve member (7) has opposing end faces (8, 9) of different effective areas. The larger area end face (8) forms a chamber (10) with the valve body part (6) past the outside of which chamber (10) fluid flows when the valve is open. The lower area end face (9) faces the valve seating (12). A first leakage path (11) is provided into the chamber (10) so that the fluid pressure in the chamber (10) equalises to that of the supply pressure. A second leakage path (15) is provided from the chamber (10) to downstream of the seating (12). The second leakage path (15) is controllable such that the fluid in the chamber (10) can escape to cause the differential forces acting on the valve member (7) to change and thus change the position of the valve member (10) relative to the seating (12). <IMAGE>

Description

Improvements relating to Valve This invention relates to valves adapted to be disposed in or at the end of a pipe for controlling the flow of a fluid (liquid or gas) through the pipe, the actuating force for the valve being provided by the pressure of the fluid and the actuation of the valve being by the differential force acting on opposite sides of a valve member which is arranged to move relatively to a valve seating and whose position controls the flow of fluid through the valve.

According to the invention in such a valve, a) the valve member has opposing end faces of different effective areas, the larger area end face of the valve member being disposed to form a chamber with the valve body past the outside of which chamber fluid flows when the valve is open and the lower area end face facing said valve seating, and b) a first leakage path is provided between the pipe and said chamber whereby the fluid pressure in said chamber equalises to that of the fluid pressure in the pipe and a second leakage path is provided from said chamber to downstream of said seating, said second leakage path being controllable such that the fluid in said chamber can escape to cause the differential forces acting on the valve member to change and thus change the position of the valve member relative to the seating.

The large area end face of the valve member may be sealingly connected to the chamber by a flexible membrane in the form of a diaphragm or a bellows. In the preferred embodiment the valve member is in the form cf a piston and the chamber constitutes a cylinder in which the piston is slidably mounted.

Embodiments of the invention in the form of liquid flow control valves will now be described by way of example with reference to the accompany drawings, in which: Figure 1 is a cross-sectional view of the valve of the first embodiment showing the valve in a closed position, Figure 2 is a cross-section of the valve of a second embodiment, and Figure 3 shows a modification of the valve of Figure 1.

The embodiment of Figure 1 comprises a sprinkler valve having a valve body 1 which is screwed into the end of a water supply pipe (not shown) by threaded inlet end 2 and projects from a ceiling. The valve as will be described is sensitive to temperature so that it will open to provide a water spray in the event of fire. The valve body 1 forms a continuation of the water supply pipe and has an outlet end 3 against which a deflector plate 4 is disposed so that the water is deflected radially outwardly to form a spray.

The central part 5 of the valve body is wider than the two ends 2 and 3 and houses an inverted cylinder 6 which is fixed in and thus forms part of the body 1 in such a way that water from the supply pipe flows past the outside of the cylinder 6 to the outlet end 3. Slidably mounted in the cylinder 6 is a piston 7 having end faces 8 and 9. The end face 8 is of larger area than the end face 9 and forms a chamber 10 with the cylinder. A leakage port 11 extends through the cylinder wall 50 so that water car enter the chamber 10 and exert a pressure on the end face 8 equal to that of the water supply pressure. The end face 9 in the closed position of the valve engages a valve seating in the form of an '0' ring 12 in which position the water supply pressure is exerted on end face 9.

From the end face 9 the piston extends downwardly for a distance within the end section 3 and seals therewith through '0' ring 13. The piston 7 has piston rod 14 screwed onhto it and which passes out of the end section 3. A bore 15 extends from the end face 8 of the piston right through the piston and piston rod and has an orifice 16 in the lower end of the piston rod.

The end of the bore 15 opening into the end face 8 is closable by a conical plug 17 which is secured to one end of a needle 18. The needle extends right through the bore 15 and at its other end connects with a snap-action bimetallic disc 19. The disc 19 is located in a widened section 20 at the bottom of the piston rod 14 and is held in position by a circlip 21. At ambient ter.~erature the bimetallic disc 19 pulls the needle 16 downwardly so that the plug 17 closes off the bore 15 from the chamber 10. The lower part of the bore 15 is sealed from the upper part by '0' seal 22 to prevent water reaching the bimetallic disc 19. A drain hole 23 leads from the upper part of the bore 15 through the piston rod 14 to allow water to drain from the chamber 10 when the plug 17 is not closing off the bore 15.

In use, the valve is maintained closed by the pressurised liquid in the supply pipe. Due te ..^ leakage of the water into the chamber 10, the pressure on larger area end face 8 is the same as that on end face 9. Hence end face 9 is forced against '0' ring seal 12.

If the temperature in the vicinity of the valve rises sufficiently for example in the event- of fire, this causes the bi-metallic disc to snap over to push the needle 18 upwards to move the conical plug 17 away from the upper end of the bore 15 to open the bore 15 so that water bleeds through the bore 15.

Now that the bore 15 is open water escapes via the drain hole 23 from the chamber 10 faster than it can enter the chamber 10 through the leakage port 11 and so the pressure acting on piston end face 8 is reduced.

Consequently the force acting on smaller area end face 9 becomes very rapidly sufficient to move the piston 7 upwards because the pressure on this end face remains the same. Thus the valve is opened so that water is sprayed out from the outlet end 3 via the deflector 4.

After the valve has opened and the ambient temperature has again dropped sufficiently the bimetallic disc 19 will snap back again and this will pull the plug 11 into the bore 15 to bring about the automatic closure of the valve. Thus the valve is a self resetting valve.

As an alternative to allowing water leakage through the port 11 the piston 7 could be a sufficiently loose fit in the cylinder as to allow water leakage past it.

In the second embodiment of the invention shown in Figure 2 the valve is a float controlled valve but works on the same principle as the first embodint.

The valve has a valve body 101 mounted at the end of a water supply pipe by threaded end section 102. Within the body 101 is a fixed cylinder 103 in which is slidably mounted a piston 104. The piston engages valve seating 105 in the form of an '0' ring to close the valve. A bore 106 is provided through the end of the cylinder corresponding to the port 11 in Figure 1. A bore 107 is provided through the piston 104 corresponding to the bore 15.

The bore 107 is closable by a conical plug 108 which is mounted on a needle 109 passing through the bores 106 and 107. The needle 109 itself does not close off the bores 106 and 107 but its repeated movement through them helps to keep them clear. The movement of the needle is controlled by a projection 110 from a pivoted float arm 111. The projection 110 engages between abutments 112 on the needle 109. Thus as the float 113 drops, the float arm 111 pivots on point 114 to cause the needle 109 to move to the left as seen in Figure 2. Eventually this movement causes the plug 108 to be removed from the bore 107 and the piston 104 moves to the left to open the valve. Movement of the float 113 upwards causes the needle to move to the right as seenin Figure 3 so that the plug eventually closes off the bore 107. The water pressure then builds up in chamber 115 and the piston 104 moves to the right to close the valve. As an alternative to the two abutments 112, the needle could be spring biased to pull the plug 108 into the bore 107 and just one abutment provided to move the needle to the left as seen in Figure 2 by movement of the piston rod 111. Thus the valve is maintained closed when the float arm is remove^.

A valve according to the invention has many applications. For example, two valves of the basic construction shown in Figure 2 could be interconnected by an arm whose movement adjusts the positions of the plugs 108 of the two valves in opposite directions relative to their respective seatings 105. One valve could be connected in a hot water supply pipe and the other to a cold water supply pipe both of which lead to a shower head. The shower temperature could be detected and control the position of the interconnecting arm so as to vary the relative positions of the plugs 108 to cause different water flows from the hot and cold pipes in a manner to maintain constant temperature.

Referring to Figure 3 this shows a modification of the valve of Figure 1, in that the piston is replaced by a valve member 51 whose end face is sealed within the chamber 10 by a flexible diaphragm 52. The diaphragm may consist of two 0 rings 53 and 54 joined together by a diaphragm 57, the two 0 rings 53 and 54 being appropriately connected to and sealed to the wall of chamber 10 and the valve member 51.

The leakage path into the chamber 10 is provided by a port 11 in the chamber wall. The diaphragm is in the form of a bellows 57, which may be a single pleat or a multi-pleat bellows as shown.

In a still further modification of the embodiment of Figure 1, the bimetallic snap-action disc 19 can be arranged to move a plunger upwardly against the bias of spring to close off bore 15 in the normally closed position of the valve. When the temperature rises the bimetallic disc will snap over to allow the spring to move the plunger downwards and so as to open the bore 15 and allow water to drain from chamber 10 through it and out of bleed hole 23. After the temperature has cooled down again the bimetallic disc 19 will snap over again to effect automatic resetting of the valve to the closed position.

Claims

1. A valve adapted to be disposed in or at the end of a pipe for controlling the flow of a fluid through the pipe, the actuating force for the valve being provided by the supply pressure of the fluid in the pipe and the actuation of the valve being by the differential force acting on opposite sides of a valve member which is arranged to move relatively to a valve seating and whose position controls the flow of fluid through the valve, wherein a) the valve member has opposing end faces of different effective areas, the larger area end face of the valve member being disposed to form a chamber with a part of the valve body past the outside of which chamber fluid flows when the valve is open and the lower area end face facing said valve seating, and b) a first leakage path is provided between the pipe and said chamber whereby the fluid pressure in said chamber equalises to that of the supply pressure in the pipe and a second leakage path is provided from said chamber to downstream of said seating, said second leakage path being controllable such that the fluid in said chamber can escape to cause the differential forces acting on the valve member to change and thus change the position of the valve member relative to the seating.

2. A valve according to claim 1, wherein the second lakage path comprises a bore through said valve member, which bore is adapted to be closed off in the closed position of the valve and to be openable to allow fluid to escape from the chamber whereby to cause tre valve to open.

3. A valve according to claim 2, wherein said bore is adapted to be closed off by a plug which is movable by actuating means to open said bore.

4. A valve according to claim 3, wherein said plug is connected to a needle which extends through said bore and which is connected to said actuating means outside said chamber for moving the needle longitudinally of said bore in order to move said plug.

5. A valve according to claim 4, wherein the needle is sprung biased in one direction and is moved in the opposite direction by said actuating means.

6. A valve according to any one of claims 3 to 5, wherein said actuating means comprise bimetallic means.

7. A valve according to claim 6 wherein said bimetallic means have a snap action.

8. A valve according to any one of claims 3 to 5, wherein said actuating means comprise a float.

9. A valve according to any preceding claim, wherein said valve member comprises a piston sliding within said chamber.

10. A valve according to any of claims 1 to 9 wherein said valve member is connected to said chamber by a flexible bellows whereby to seal the large area end face within said chamber.

11. A valve substantially as hereinbefore described with reference to Figures 1, 2 or 3 of the accompanying drawings.