Device for controlling fluid flow

Abstract

A device (1) for controlling the flow of a fluid through a conduit (3) from an upstream side (8) to a downstream side (10). The device includes a housing (4) having one or more valve apertures (6) through which the flow of fluid is selectively controlled. A valve member (12) is mounted on the housing and arranged to move reciprocally to selectively open and close the one or more valve apertures. A seal (20) is arranged at or beyond a position the valve member reaches when the one or more valve apertures are all closed. The device also includes a resilient member (26) that acts to bias the seal towards the valve member.

Claims

1. A device for controlling a flow of a fluid through a conduit from an upstream side of the device to a downstream side of the device, the device comprising: a housing having defined therein one or more valve apertures through which the flow of fluid is selectively controlled; a valve member mounted on the housing and arranged to move reciprocally to selectively open and close the one or more valve apertures, thereby controlling flow of the fluid through the one or more valve apertures; a moveably mounted seal arranged at or beyond a position the valve member reaches when the one or more valve apertures are all closed; and a resilient member that acts to bias the seal towards the valve member, wherein the resilient member comprises an O-ring; and wherein the valve member is arranged to come into contact with the seal when the valve member reaches or passes the position at which the one or more valve apertures are all closed such that the valve member acts on the seal against the bias of the resilient member, and the seal acts to provides a barrier to the flow of fluid between the upstream and downstream sides of the device.

2. The device as claimed in claim 1, wherein the housing comprises a cylinder, and the valve member comprises a cylinder mounted coaxially on an outside of the housing and arranged to move reciprocally in a direction in which the housing and the valve member are cylindrically extended.

3. The device as claimed in claim 2, wherein the valve member comprises a circular rim arranged to come into contact with the seal when the valve member reaches or passes the position at which the one or more valve apertures are all closed.

4. The device as claimed in claim 3, wherein the circular rim of the valve member comprises a mating surface arranged to come into contact with a cooperating mating surface of the seal.

5. The device as claimed in claim 3, wherein the circular rim of the valve member comprises a chamfered edge.

6. The device as claimed in claim 5, wherein a mechanically exerted pressure of the chamfered edge on the seal is greater than a fluid pressure differential between the upstream and downstream sides of the device.

7. The device as claimed in claim 1, wherein the valve member comprises a stop arranged to engage with the housing to limit travel of the valve member past a point at which the valve member comes into contact with the seal.

8. The device as claimed in claim 7, wherein when the stop of the valve member engages with the housing, a contact force between the stop of the valve member and the housing is greater than a contact force between the valve member and the seal.

9. The device as claimed in claim 1, wherein the seal comprises an annular seal with a quadrilateral cross section.

10. The device as claimed in claim 1, wherein the seal comprises a plastic material.

11. The device as claimed in claim 1, wherein the seal and/or the resilient member are mounted on an outside of the housing.

12. The device as claimed in claim 1, wherein the seal and/or the resilient member are mounted in a groove that extends circumferentially around the housing.

13. The device as claimed in claim 12, where the seal and/or the resilient member are mounted in the groove so as to radially float in the groove.

14. A device for controlling flow of a fluid through a conduit from an upstream side of the device to a downstream side of the device, the device comprising: a housing having defined therein one or more valve apertures through which the flow of fluid is selectively controlled; a valve member mounted on the housing and arranged to move reciprocally to selectively open and close the one or more valve apertures, thereby controlling flow of the fluid through the one or more valve apertures; a moveably mounted seal arranged at or beyond a position the valve member reaches when the one or more valve apertures are all closed; and a resilient member that acts to bias the seal towards the valve member; wherein the valve member is arranged to come into contact with the seal when the valve member reaches or passes the position at which the one or more valve apertures are all closed, such that the valve member acts on the seal against the bias of the resilient member and the seal acts to provides a barrier to the flow of fluid between the upstream and downstream sides of the device; and wherein the valve member comprises a stop arranged to engage with the housing to limit travel of the valve member past a point at which the valve member comes into contact with the seal.

15. A device for controlling a flow of a fluid through a conduit from an upstream side of the device to a downstream side of the device, the device comprising: a housing having defined therein one or more valve apertures through which the flow of fluid is selectively controlled; a valve member mounted on the housing and arranged to move reciprocally to selectively open and close the one or more valve apertures, thereby controlling flow of the fluid through the one or more valve apertures; a moveably mounted seal arranged at or beyond a position the valve member reaches when the one or more valve apertures are all closed; and a resilient member that acts to bias the seal towards the valve member; wherein the valve member is arranged to come into contact with the seal when the valve member reaches or passes the position at which the one or more valve apertures are all closed such that the valve member acts on the seal against the bias of the resilient member and the seal acts to provides a barrier to the flow of fluid between the upstream and downstream sides of the device; and wherein one or more of the valve member, the moveably mounted seal, and the resilient member are mounted on an outside of the housing.

Description

(1) Certain preferred embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings in which:

(2) FIG. 1 shows a cross-section view of a fluid flow control device in accordance with an embodiment of the present invention; and

(3) FIG. 2 shows a cross-section view of a fluid flow control device in accordance with another embodiment of the present invention.

(4) There are many different industrial situations in which there is a desire to regulate the pressure in a fluid flow stream through a pipe or conduit. In such systems there is an input pressure that may be constant or fluctuating in time and which it is desired to control to a lower target output pressure, which also can be constant or fluctuating. As will now be described, embodiments of the present invention provide devices that are able to provide this control for the fluid flow.

(5) FIG. 1 shows a cross-sectional view of a fluid flow control device 1 in accordance with an embodiment of the present invention. The device 1, e.g. a pressure regulator, includes a metal flange 2 for mounting the device 1 in a section of pipe 3, e.g. clamped between a joint in the pipework. The device also includes a metal housing 4 that has a cylindrical body in which a plurality of valve apertures 6, extending axially through the cylindrical housing 4, are formed. The housing 4 is attached to and extends perpendicularly to the flange 2, projecting into a downstream side 10 of the pipe 3.

(6) The plurality of valve apertures 6 allow fluid to pass from an upstream side 8 of the pipe 3 to the downstream side 10 of the pipe 3. The flow of the fluid through the plurality of valve apertures 6 is controlled by a cylindrical metal valve member 12 that is mounted coaxially on the outside of the cylindrical housing 4, and arranged to move reciprocally in a direction parallel to the main cylindrical axis of the housing 4 and the valve member 12. The valve member 12 has a cap 13 at its end that is arranged to abut the end 15 of the housing 4 when the valve member 12 is fully closed, i.e. when it is covering all of the valve apertures 6. At the other end of the valve member 12, the circular rim has a chamfered end 11.

(7) A plenum chamber 17, defined between the end 15 of the housing 4 and the cap 13 of the valve member 12, allows a control pressure to be introduced into the control volume of the plenum chamber 17 via a pipe 19, e.g. from a pilot pressure regulator (not shown).

(8) The housing 4 is mounted on the flange 2, along with an outer casing 14 (in which a plurality of apertures 16 are formed), such that they define a first annular groove 18 in which an annular seal 20, having a square cross section and made from PTFE, is located. An overhanging lip 22 in the outer casing 14 is provided for the first groove 18 to retain the seal 20 in the first groove 18. These components can be seen more clearly in the magnified view shown in FIG. 1.

(9) A second annular groove 24, smaller than the first annular groove 18, is defined in the first annular groove 18, and a resilient O-ring 26, having a circular cross section and made from nitrile rubber, is located in this second groove 24, held in place by the seal 20. As can be seen from the magnified view shown in FIG. 1, the O-ring 26 biases the seal 20 against the lip 22 of the first groove 18, though the O-ring 26 and the seal 20 are arranged (by their dimensions) such that they are radially floating (and thus pressure balanced) in their respective grooves 24, 18.

(10) Operation of the fluid flow control device 1 in accordance with this embodiment of the invention will now be described with reference to FIG. 1.

(11) With the fluid flow control device 1 installed in a pipe 3, i.e. mounted in the pipe 3 by its flange 2, and with a control pressure P.sub.2 introduced into the plenum chamber 17 via the pipe 19 from a pilot pressure regulator (not shown), variations in the pressures (P.sub.1 and P.sub.3 respectively) in the pipe 3 on the upstream 8 and downstream 10 sides of the device 1 cause the valve member 12 to move reciprocally to open and close the plurality of valve apertures 6 in the housing 4, in order to control the flow of fluid through the device 1.

(12) When the valve member 12 closes fully and thus shuts all the plurality of valve apertures 6 in the housing 4, the capped end 13 of the valve member 12 abuts against the end 15 of the housing 4, with a closing force that may reach several tens of kilonewtons, the majority of which is taken by the capped end 13 of the valve member 12 abutting against the end 15 of the housing 4. As the end 13 of the valve member 12 comes into contact with the end 15 of the housing 4, the other end 11 of the valve member 12 (i.e. the chamfered circular rim) comes into contact with the annular seal 20 that is held in the larger groove 18, though with a much reduced contact force.

(13) The force of the end 11 of the valve member 12 on the seal 20 pushes the seal 20 against the O-ring 26 which is located in the smaller groove 24. As can be seen from the magnified section of FIG. 1, there is a small distance through which the seal 20 may be moved until it abuts against the bottom of the groove. The force of the end 11 of the valve member 12 through the seal 20 thereby compresses and deforms the O-ring 26 within the smaller groove 24, thus forming an effective barrier for fluid between the upstream 8 and downstream 10 sides of the pipe 3 and thus providing effective shut-off for the device. The barrier is enhanced by the chamfered end 11 of the valve member 12, which increases the local, mechanically exerted pressure between the chamfered end 11 and the seal 20 (compared to a flat end).

(14) When the valve member 12 is closed, the biasing of the O-ring 26 on the seal, along with the pressure differential between the upstream pressure P.sub.1 and the downstream pressure P.sub.3 maintain the barrier between the upstream and downstream sides of the device 1.

(15) Owing to the seal 20 being biased (sprung) by the resilient O-ring 26, this helps to reduce the force of the valve member 12 that is experienced by the seal 20. This thus helps to reduce the wear of the seal 20 by the valve member 12. Over repeated use of the device 1, and thus repeated impacts of the end 11 of the valve member 12 against the seal 20, the seal 20 will eventually wear (albeit at a slower rate). However, owing to the compliance provided to the seal 20 by the biasing of the O-ring 26, an effective barrier will still be provided, when the valve member 12 is closed, for fluid between the upstream 8 and downstream 10 sides of the device 1.

(16) FIG. 2 shows a cross-sectional view of a fluid flow control device 101 in accordance with another embodiment of the present invention. The device 101 is very similar to the embodiment shown in FIG. 1, except for the details shown in the magnified section.

(17) As in the embodiment shown in FIG. 1, a housing 104 is mounted on a flange 102, along with an outer casing 114, such that they define a first annular groove 118 in which an annular seal 120, having a rectangular cross section and made from PTFE, is located. The seal 120 is retained in the first groove 118 by a stainless steel retaining ring 128, which itself is retained in the first groove by an overhanging lip 122 in the outer casing 114.

(18) A second annular groove 124, smaller than the first annular groove 118, is defined in the first annular groove 118, and a resilient O-ring 126, having a circular cross section and made from nitrile rubber, is located in this second groove 124, held in place by the seal 120. As can be seen from the magnified view shown in FIG. 2, the O-ring 126 biases the seal 120 against the lip 122 of the first groove 118 via the retaining ring 128.

(19) Operation of the fluid flow control device 101 in accordance with the embodiment shown in FIG. 2 is the same as described above for the embodiment shown in FIG. 1.

(20) It can be seen from the above that in at least preferred embodiments, the fluid control flow device of the present invention provides a device for controlling the flow in a conduit in which a biased seal helps to provide an effective barrier at shut-off of the valve to the flow of fluid between the upstream and downstream sides of the device. The biased seal is particularly wear resistant, owing to its compliance, and maintains an effective seal even when it is at least partially worn.