GB2158201A

GB2158201A - Improvements relating to valve assemblies

Info

Publication number: GB2158201A
Application number: GB08508896A
Authority: GB
Inventors: Sean Alfred Mayo; Geoffrey Thomas Baxter
Original assignee: SERVICON DYNAMICS
Current assignee: SERVICON DYNAMICS
Priority date: 1984-04-04
Filing date: 1985-04-04
Publication date: 1985-11-06
Also published as: GB2158201B; GB8508896D0; GB8408643D0

Abstract

A valve body 1, forming part of a fluid supply pipe of a central heating radiator, carries a valve incorporating a magnetic plunger 3 biased down onto a valve seat 6 by a spring 7. An operating pulse passed through a coil 9 is sufficient to enhance the magnetic field of a permanent magnet 13 to draw the plunger 3 upwardly to remove the valve head 4 from the valve seat 6. When the plunger 3 is in the raised position the magnetic field of the magnet 13 alone is sufficient to hold the plunger 3 in the raised position against the bias of the spring 7. A pulse passed in the opposite direction through the coil 9 will create a magnetic field in opposition to that created by the magnet 13 so that the overall magnetic field will then be insufficient to overcome the bias of the spring 7 and the plunger 3 will return the valve to the closed condition. <IMAGE>

Description

SPECIFICATION Improvements relating to valve assemblies This invention is concerned with a valve for incorporation within a fluid supply pipe. A particular area in which such a valve would be particularly suitable is in association with radiators in domestic central heating systems fed from a boiler by a pump.

It is an object of this invention to provide a valve which is simple and efficient in construction, requiring low power usage for operation.

Accordingly this invention provides a valve for a fluid supply pipe, comprising a magnetic plunger having a valve head, at one end of the plunger, which is biased into contact with a valve seat by a spring, the plunger being housed within an electrical coil, the coil housing incorporating a permanent magnet spaced beyond the other end of the plunger, at least when the valve head is in contact with the valve seat, the magnet being of a strength sufficient to overcome the spring bias after the plunger has been drawn towards the magnet upon passing an operating pulse through the coil to cause opening of the valve.

Since the means for operating the plunger does not incorporate a soft iron core any operating pulse passed through the coil does not have to be large enough to effect polarity reversal. When a pulse is passed through the coil the field of the permanent magnet is increased thus enabling the bias of the spring to be overcome. The plunger is then held in the open condition by the magnet even when no current is passing through the coil. Then, when a pulse is passed in the opposite direction through the coil, the magnetic field passing through the plunger is reduced so that the spring overcomes this reduced magnetic field and closes the valve. The plunger will then be positioned further away from the permanent magnet so that the magnetic field from the magnet passing through the plunger is insufficient to open the valve on its own.

Ideally the coil will be mounted in a magnetic housing which is associated with the permanent magnet, thus creating a good magnetic flux path. It is preferred, however, that the plunger should be mounted within a nonmagnetic sleeve about which the coil is formed. The metallic parts housing the coil and the plunger are ideally formed from stainless steel. The preferred form of magnet used is a ceramic magnet.

Advantageously the valve will incorporate a closure member which closes the other end of a housing chamber of the plunger and incorporates a screw-threaded rod having a head which can be moved down to hold the plunger down so that the valve head is in contact with the valve seat. When the plunger is held down by the rod, the valve is held in a permanently closed position so that an associated radiator, for example, is isolated from the fluid supply system and can be removed for maintenance or replacement. The head of the rod might incorporate a resilient buffer to reduce accoustic disturbance upon operation of the plunger when the valve is in the normal operating condition. The closure member can also incorporate a bleed passageway which is opened upon rotation of the rod to move the head thereof away from the closure member.

This enables air to be bled out of the system if required.

The invention may be performed in various ways and a preferred embodiment thereof will now be described with reference to the accompanying drawing which comprises a partial vertical cross-section through a valve assembly of this invention.

The valve unit shown in the drawing has a bronze valve body 1 to which is mounted a plunger and coil housing 2. The plunger 3 within the housing carries a valve head 4 incorporating a rubber disc washer 5 associated with a valve seat 6 of the valve body 1.

The valve head 4 is biased into the closed condition by a spring 7. A stainless steel nonmagnetic sleeve 8 housing the plunger 3 has a coil 9 wound thereabout. The coil is retained within a magnetic steel tube 10 closed at top and bottom by magnetic steel plates 11 and 1 2. A ceramic magnet 1 3 is held between the plate 11 and a top plate 14 (also of magnetic steel) and the assembly of the plates 11,12 and 14 and the magnet 13 is clamped tightly together between a spine washer 1 5 and a magnetic steel base part 1 6.

The base 1 6 is held by an anti-rotation bracket 26 and extends downwardly at 1 7 to surround the lower end of the sleeve 8, which is itself closed by a thrust washer 1 8. All the metallic parts, including the plunger 3, are formed from stainless steel.

A magnetic steel closure member 1 9 closes off the upper end of the sleeve 8, leaving a gap 20 for movement of the plunger 3 within the sleeve 8. The magnet 1 3 and plate 11 are positioned about the closure member 1 9 by a locating bush 27. The top unit incorporates a screw-threaded rod 21. Access to the rod 21 is achieved by removing a screw-threaded plug 22 and a gasket 23. The rod 21 can then be rotated so that the head 22 moves downwardly. This opens a bleed passageway (not shown) which enables air within the system and the valve unit to be bled off. When the rod is screwed fully down the head 22 will be pressed against the plunger 3 thus holding the valve in the closed condition. A radiator, for example, mounted on the pipe portion 24 of the valve body 1 can then be removed.

When the valve is in the closed condition as illustrated in the drawing the spring 7 is effective to overcome the magnetic field pro duced by the permanent magnet 13 tending to draw the plunger 3 upwardly and also resists the force applied to the valve head 4 by the water pressure created by a pump in a central heating system of which the valve is a part. However a pulse can be passed through the coil 9 which will enhance the magnetic field created by the magnet 1 3 and the magnetic parts of the housing 2 such that the opposing force of the spring 7 is overcome and the plunger 3 is drawn up into contact with the closure member 1 9 (which forms part of the magnetic circuit).When the plunger is in this position the magnetic field is strong enough to hold the plunger 3 in the open condition against the bias of the spring 7 even when no current is passing through the coil 9. Then when a pulse is passed in the opposite direction through the coil 9 a magnetic field will be created in opposition to that created by the magnet 1 3 so that the overall magnetic field is reduced and the spring 7 will cause the plunger 3 to return the valve to the closed condition.

The valve is intended for normal operation with the water flowing in the direction indicated by the arrow 25. However, the valve will operate equally well if the normal flow introduced by the pump is in the opposite direction. Hence no damage will be caused if the valve is deliberately or inadvertently incorporated "the wrong way round" onto a radiator. It will also be appreciated that the valve can readily be modified for use with pipes of larger sizes by pressing an insert having a larger size opening onto one or other end of the valve body 1.

The valve unit can be operated by a low current pulse and will have a very fast operational speed as there is no requirement for reversal of the magnetic polarity of a soft iron core. The shaping and positioning of the ceramic magnet pole piece and the magnet circuit formed by the various parts of the housing 2 which are clamped together creates a very good magnetic circuit with a concentrated field.

Claims

1. A valve for a fluid supply pipe, comprising a magnetic plunger having a valve head, at one end of the plunger, which is biased into contact with a valve seat by a spring, the plunger being housing within an electrical coil, the coil housing incorporating a permanent magnet spaced beyond the other end of the plunger, at least when the valve head is in contact with the valve seat, the magnet being of a strength sufficient to overcome the spring bias after the plunger has been drawn towards the magnet upon passing an operating pulse through the coil to cause opening of the valve.

2. A valve according to claim 1, wherein the coil is mounted in a magnetic housing which is associated with the permanent magnet.

3. A valve according to claim 1 or claim 2, wherein the plunger is mounted within a non-magnetic sleeve about which the coil is formed.

4. A valve according to any one of claims 1 to 3, wherein metallic parts housing the coil and the plunger are formed from stainless steel.

5. A valve according to any one of claims 1 to 4, wherein the magnet is a ceramic magnet.

6. A valve according to any one of claims 1 to 5, wherein a closure member which closes the other end of a housing chamber of the plunger incorporates a screw-threaded rod having a head which can be moved down to hold the plunger down so that the valve head is in contact with the valve seat.

7. A valve according to claim 6, wherein the head of the rod incorporates a resilient buffer.

8. A valve according to claim 6 or claim 7, wherein the closure member incorporates a bleed passageway which is opened upon rotation of the rod to move the head thereof away from the closure member.

9. A valve for a fluid supply pipe substantially as herein described with reference to the accompanying drawing.