WO1992007210A1

WO1992007210A1 - Valves

Info

Publication number: WO1992007210A1
Application number: PCT/GB1991/001825
Authority: WO
Inventors: John Keir Haffenden
Original assignee: Dansam Holdings Limited
Priority date: 1990-10-18
Filing date: 1991-10-18
Publication date: 1992-04-30
Also published as: AU8731691A; GB9022637D0

Abstract

A valve has a valve member (8) carried on a displaceable element (12). The displaceable element (12) is resiliently biased towards the closed position of the valve but is normally held in the open position by magnets (64). A release winding (32) can be energized to overcome the magnetic field of the magnets (64), so allowing the valve to close. The release winding (32) may be energized in response to predetermined circumstances, for example flow through the valve for longer than a predetermined time.

Description

VALVES

This application relates to valves, and particularly, although not exclusively, to valves which are normally open but, in certain circumstances, are closed under the action of a resilient biassing force after release of retaining means.

GB-A-2179425 discloses a valve comprising an elongate displaceable element carrying a valve member for movement between open and closed positions, the displaceable element being resiliently biassed in one direction and being retained against displacement in that direction by a retaining element, the retaining element being operable to release the displaceable element for movement in the direction of resilient bias.

The retaining element is a plunger which engages a recess in the displaceable element, and is retractable by means of a solenoid, to release the displaceable element. The valve of GB-A-2179425 is used in domestic water systems. The valve is normally held open by the plunger. A flow sensor and a timing circuit are provided, and give a signal when flow through the valve has continued for more than a predetermined time. The signal causes the solenoid to be energized to withdraw the plunger, allowing the valve to close under the action of the resilient bias, so terminating the flow of water.

Valves for such purposes are required to operate (i.e. close) reliably, even after remaining idle for a considerable period, which may amount to several years. A problem with the valve of GB-A-2179425 is that the plunger may sometimes stick, or jam in the recess in the displaceable element, and so will not be retracted when the solenoid is energized. Another disadvantage is that, even if the plunger is withdrawn, the displaceable member may stick or jam and so the valve will fail to close. Also, the plunger and the solenoid occupy a relatively large space, so that it is difficult to make the valve compact.

According to the present invention there is provided a valve comprising an elongate displaceable element carrying a valve member for movement between open and closed positions, the displaceable element being resiliently biassed in one direction and having a magnetically susceptible region which is acted upon by the magnetic field of a permanent magnet to retain the displaceable element against displacement, a release winding being provided which is energisable to create a magnetic field opposing the magnetic field of the permanent magnet, so as to cause the displaceable element to be released for movement in the direction of resilient bias.

In a preferred embodiment, two permanent magnets are provided. They are mounted on opposite sides of a support body, with like poles facing each other. The support body also provides a bobbin portion, on which the release winding is carried. The magnetically susceptible region of the displaceable element extends into a passage in the support body passing between the magnets and through the release winding. A stop may be provided for abutment by the displaceable element when the valve is in the open position. A frame may extend partially around the body, between the magnets, to provide a magnetic circuit. The displaceable element and the valve member may be spring loaded towards the closed position. The magnetic field of the permanent magnet then retains the displaceable element to hold the valve member in the open position until the winding is energised to cause release of the displaceable element, allowing the valve member to move to the closed position. The release winding may be controlled automatically so that the displaceable element is released.under predetermined circumstances. For example, the displaceable element may be released after a predetermined time has elapsed from an initiating event. The initiating event may be the initial flow of water through a valve, so that the valve member will move to close the valve after water has flowed for a predetermined time. One use of such a valve is to prevent extensive flooding in industrial, commercial or domestic properties as a result of a burst pipe or other leakage. The predetermined time lapse will be set to exceed the maximum duration of flow under normal circumstances. However, if, for example, a pipe bursts, then the resulting continued flow through the valve will eventually cause the release winding to be energised, so releasing the displaceable element to allow the valve member to move to the closed position, preventing further discharge of water. Alternatively, the valve could be adapted for use, for example, in a sub-sea wellhead installat _*n, for shutting off oil flow in an emergency. The valve may be actuated to close auto aticclly or manually, and may be operable remotely from an oil rig or from the shore, perhaps via a radio link.

For a better understanding of the present invention, and to show how it may be carried into effect, reference will now be made, Ly way of example, to the accompanying drawings, in which: Figure 1 is a sectional view of an automatic shut- off valve;

Figure 2 is a side view of the valve of Figure 1; Figure 3 shows a permanent magnet latch used in the valve of Figures 1 and 2; and Figures 4 and 5 represent, diagrammatically, the operation of the permanent magnet latch. Referring first to Figures 1 and 2, the valve comprises an inlet spigot 2 and an outlet spigot 4, which communicate with each other past a valve seat 6. A valve member 8 is mounted in a housing 10 for movement between a closed position (represented by the lower half of the valve member 8 as shown in Figure 1) and an open position (represented by the upper half of the valve member 8). The valve member 8 is carried by a displaceable element 12 in the form of a valve stem which is movable in a valve guide 14 accommodated in the housing 10. At its end away from the valve seat 6, the housing 10 is provided with a cap 16 having a passage 18 through which a steel portion 19 of the valve stem 12 projects. The end of the steel portion 19 has an annular rib 20, and a spring 22 acts between the rib 20 and the cap 16 to bias the valve member 8 towards the seat 6.

The cap 16 constitutes the end portion of a support body 34 of a magnetic latch 35. The body 34 is made from a material, such as a plastics material, which is not magnetically susceptible. The passage 18 extends the full length of the support body 34, but its end away from the valve member 8 is closed by a stop 36. The support body 34 has two oppositely disposed recesses 38 and an annular channel 40. Each recess 38 accommodates a permanent magnet 64, and the channel 40 accommodates a release winding 32. The magnets 64 are disposed with their magnetic axes oriented radially, and with like poles facing towards each other (see Figures 5 and 6).

At the end of the steel portion 19, there is a threaded spindle 42 which passes through the stop 36 and carries a knob 24. The knob is normally enclosed by a removable transparent cover 26. A yoke 44 of magnetically susceptible material straddles the body 34 and provides a magnetic circuit between the permanent magnets 64. The yoke has an opening 46 in which the stop 36 is fitted.

The magnetic latch 35 is shown on an enlarged scale in Figure 3, and its principle of operation is shown in Figures 4 and 5.

Referring to Figure 4, when the winding 32 is not energised, the permanent magnets create a magnetic field as represented by arrows. This magnetic field generates an attractive force between the steel portion 19 of the valve stem 12 and the stop 36, and so the valve member 8 is magnetically retained in the retracted position, against the restoring force of the spring 22.

When the winding 32 is energized, current flowing in the appropriate direction will create its own magnetic field, represented in Figure 5 by arrows drawn in phantom. It will be appreciated that this magnetic field opposes that created by the permanent magnets 64 and, provided the current flowing in the winding 32 is of the appropriate magnitude, may neutralize it. The valve stem 12 will then be moved to the left, as shown in Figure 1, by the spring 22, so closing the valve.

A rocker lever 28 is pivotally mounted in the valve guide 14 and projects inwardly of the housing 10 towards the valve stem 12. Outside the housing 10, the lever 28 is positioned to actuate an electrical switch 30.

As shown on Figure 1, the valve member 8 has a balance shaft 48 projecting from it in the direction away from the valve stem 12. The balance shaft 48 is received in a sleeve 50 formed on the housing 10. A reed switch 68 is provided which is responsive to flow between the inlet and outlet spigots 2 and 4. Control circuitry (not shown) is provided in the device for controlling the operation of the winding 32. The control circuitry receives signals from the reed switch -6-

68 and incorporates a timer for purposes which will be discussed below.

The device may be used for several different purposes, but one use is as a safety device to prevent extensive flooding in the event of a burst pipe or other major leakage in a domestic water system. For such a purpose, the device is installed in the primary supply to the premises concerned, either where the mains supply enters the premises, or in the outlet of a main cold water storage tank. The control and operating circuitry is connected to an appropriate electrical supply such as the mains supply or a battery. In normal use, the valve member 8 will be retracted from the seat 6 to allow water to flow through the device for consumption in the normal way. Thus, the valve stem 12 is retracted to the right (as shown for the upper half of the valve stem in Figure 1) against the action of the spring 22. The valve stem 12 is retained in this position, abutting the stop 36, by the magnetic field created by the permanent magnets 64. For much of the time, there will be no flow through the device because there will be no consumption of water in the premises. If, however, a bath is to be filled, the turning on of the bath taps will cause water to flow through the device, and this will trigger the reed switch 68, so that a signal will be applied to the control circuitry. The timer in the control circuitry will normally be set to provide a delay of, for example, fifteen minutes before the control circuitry causes energisation of the release winding 32. If flow through the device stops before fifteen minutes have elapsed, the timer resets to zero. Thus, if filling of the bath takes, for example, ten minutes, the winding 32 will not be energized and the device will remain open.

However, should a water pipe downstream of the device burst, the flow of water through the device will be continuous. Once the flow has continued for the time delay set by the timer, the control circuitry will be actuated to energise the release winding 32, so neutralizing the magnetic field created by the permanent magnets 64. This will release the valve stem 12, and the valve will be moved to the closed position, against the seat 6, under the action of the spring 22. The flow of water from the burst pipe will then be stopped, and any resulting damage to the property will be mitigated.

The balance shaft 48 reduces the area of the valve member 8 exposed to the liquid flowing in the device, and so avoids the application of undesired forces in the opening direction of the valve as a result of any pressure differential existing across the valve member 8. This improves the operating smoothness and reliability of the device.

To reset the device, the winding 32 is de- energised, and the valve member 8 is opened manually by pulling out the knob 24 until the steel portion 19 is held by the magnetic field created by the magnet 64. Alternatively, resetting can be achieved by energizing the winding 32 in the reverse direction, so its magnetic field supplements that of the magnets 64 to retract the valve stem 12 against the action of the spring 22.

A useful feature of the device is that, even should the power supply to the winding 32 fail, the valve can be closed manually. This is done by removing the cover 26 and pushing on the knob 24. This overcomes the magnetic force on the steel portion 19, allowing the valve to close under the action of the spring 22. The cover 26 encloses various indicating lights and control devices, as shown in Figure 2. Thus, there is an adjustment control 70 for adjusting the time delay between the beginning of flow through the device, as detected by the reed switch 68, and the energisation of the winding 32. There is also a push-button 72 for energising the winding 32 at any desired time in order to cause the valve to close. A further push button 74 is provided for overriding the timer in the event that continuous flow, for longer than the pre-set time, is required, for example if a hose pipe is to be used. Indicating lamps 76, 78 and 80 indicate, respectively, that the power is on, that the valve is open and that the override button 74 has been actuated. The lamp 78 is responsive to the switch 30. In the position shown in Figure 1, the switch 30 is open, and this will cause the control circuitry to illuminate the lamp 78. If the valve is closed, the upper half of the valve stem 12, as shown in Figure 1, is moved to the left and the rocker 28 will be engaged by the annular rib 20 to close the switch 30. This will extinguish the lamp 78.

Claims

1. A valve comprising an elongate displaceable element (12) carrying a valve member (8) for movement between open and closed positions, the displaceable element (12) being resiliently biassed in one direction, characterized in that the displaceable element (12) has a magnetically susceptible region (19) which is acted upon by the magnetic field of a permanent magnet (64) to retain the displaceable element (12) against displacement, a release winding (32) being provided which is energisable to create a magnetic field opposing the magnetic field of the permanent magnet (64), so as to cause the displaceable element (12) to be released for movement in the direction of resilient bias.

2. A valve as claimed in claim 1, characterized in that the magnet (64) is one of two permanent magnets (64) which are mounted on opposite sides of a support body (34), with like poles facing each other.

3. A valve as claimed in claim 2, characterized in that the support body (34) has a channel (40) in which the release winding (32) is carried.

4. A valve as claimed in claim 3, characterized in that the magnetically susceptible region (19) of the displaceable element (12) extends into a passage (18) in the support body (34) passing between the magnets (64) and through the release winding (32).

5. A valve as claimed in any one of the preceding claims, characterized in that a stop (46) is provided for abutment by the displaceable element (12) when the valve is in the open position.

6. A valve as claimed in any one of the preceding claims, characterized in that a frame extends between the magnets (64), to provide a magnetic circuit.

7. A valve as claimed in any one of the preceding claims, characterized in that the displaceable element (12) and the valve member (8) are spring loaded towards the closed position.

8. A valve as claimed in any one of the preceding claims, characterized in that the release winding (32) is controlled automatically so that the displaceable element (12) is released under predetermined circumstances.