GB2181818A

GB2181818A - Fluid flow control valve

Info

Publication number: GB2181818A
Application number: GB08525761A
Authority: GB
Inventors: Keith Wilkinson
Original assignee: TI Domestic Appliances Ltd
Current assignee: TI Domestic Appliances Ltd
Priority date: 1985-10-18
Filing date: 1985-10-18
Publication date: 1987-04-29
Also published as: GB2181818B; GB8525761D0

Abstract

A fluid-flow control valve comprises a passage 14 through which fluid is to flow between an inlet 11 and an outlet 12, a volume of ferro-fluid 24 separated from the flowing fluid by a body such as a flexible envelope 23 and an electromagnet circuit 18, 19, 20, 21, operable in conjunction with a permanent magnet 17 for controlling the ferro-fluid 24 to make the body and thereby vary the fluid flow through said valve. <IMAGE>

Description

SPECIFICATION Fluid flow control valve This invention relates to fluid flow control valves and is applicable particularly, but not exclusively, to electrically operated gas valves.

According to the invention a fluid flow control valve includes a passage through which the fluid is to flow, a body movable in or across the passage to vary the fluid flow, a volume of ferro-fluid separated by the body from the first mentioned fluid, and an electro- magnet arranged when supplied with an electric current to exert a magnetic force on the volume of ferro-fluid and thereby move the body to vary the fluid flow.

The body may be a diaphragm such as elastomeric and the volume of ferro-fluid may be contained in an elastomeric envelope.

Preferably the ferro-fluid filled envelope is retained within the passage and is caused the electric current to roll between two positions, in one of which the passage is relatively open for flow of the fluid, and in the other position the passage is partially or completely blocked.

The invention is described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is an enlarged section in a vertical plane through one embodiment of the invention; Figure 2 is a section along the line ll-ll in Fig. 1; Figure 3 is an alternative to Fig. 1, and Figure 4 shows a further alternative to Figs.

1 and 2.

The drawings show various embodiments of the invention suitable for controlling the flow of combustible gas to a domestic appliance, such as a boiler, water heater, cooker etc.

In Figs. 1 and 2 a valve body 10, typically of cast brass has a gas inlet 11 and gas outlet 12. The inlet 11 is connected by a vertical passage 13 into a valve chamber 14, separated from the outlet 12 by a wall 15 into which is fitted a block 16.

A permanent magnet 17 is fitted with substantially identical opposing soft iron pole pieces 18 formed with inclined first poles 19, adjacent the left-hand end of the chamber 14, and second poles 20 located on opposite sides of the block 16. Electrical windings 21 are wound around the second poles 20. The chamber 14 and outlet 12 are interconnected by three bores 22, which are shown in the same plane in Figs. 1 and 2, but which could be spaced along the block 16 if preferred.

Within the chamber 14 there is an elastomeric diaphragm in the shape of a thin, tough and highly flexible polyurethane envelope 23 filled with a quantity of ferro-fluid 24 (unshown in Fig. 2, for clarity).

Since the pole pieces 18 are fastened and magnetically connected to opposite poles of the magnet 17, the poles 19 will be of opposite polarity, as will the poles 20, so that a magnetic field will extend between the poles 19 and also between the poles 20.

The ferro-fluid 24 has the property of being attracted by a magnet, similar to a piece of soft iron. Such ferro-fluids are well known in themselves and comprise plastic coated ferromagnetic particles suspended colloidally in a carrier fluid. The viscosity of the carrier fluid can be selected to suit the particular applications. A short length of the envelope 23 is fastened by adhesive to the base of the chamber 14, as shown at 25.

The proportions and dispositions of the poles 19 and 20 are arranged so that, when no electrical current passes through the windings 21, the poles 20 exert a greater force than the poles 19 on the ferro-fluid 24, so that the envelope 23 is caused to roll along the chamber 14 and up to the right-hand end thereof, so that it seals off the ends of the bores 22, thus preventing flow of gas from inlet 11 to the outlet 12.

However, the windings 21 are arranged so that when an appropriate electric current is passed through them, they generate a magnetic field in the poles 20 which opposes and reduces the magnetic field in the poles 20 due to the permanent magnet 17. Thus, the magnetic field between the poles 19 then predominates and the ferro-fluid 24 is attracted to the left, so that the envelope 23 rolls to the lefthand end of the chamber 14 to open a passage from the inlet 11 through the passage 13, the chamber 14 and the bores 22 to the outlet 12. As the current in the windings 21 is reduced, the net magnetic field between the poles 20 will increase and progressively draw the envelope 23 towards the right-end of the chamber 14.The envelope 23 first reaches and closes the lower bore 22, then the central bore and finally the upper bore, so that flow of gas can be controlled by varying the current in the windings 21, as required.

In Figs. 3 and 4 the permanent magnet 17 is located towards the right-hand end of the chamber 14 with its upper pole adjacent the base thereof and its lower pole magnetically connected to a horseshoe-shaped pole piece 18 having poles 19, 20 located adjacent the opposite ends of the chamber 14. In Fig. 3, one of the bores 22 is located in the righthand end of the chamber 14 and the other two bores 22 are located in the base thereof, whereas in Fig. 4 all three bores 22 are located in the base of the chamber 14. In Fig. 3 the envelope 23 containing the ferro-fluid 24 is free to roll along the base of the chamber 14. When no current passes through the winding 21, the magnetic field between the upper pole of the permanent magnet 17 and the pole 20 will be stronger than that between the upper pole of the permanent mag net 17 and the pole 19.Thus, the ferro-fluid 24 and envelope 23 will be drawn to the right-hand side to close all three bores 22. As current in the winding 21 is increased the net magnetic field through the pole 20 will be reduced so that the envelope 23 will be drawn towards the left, progressively uncovering the bores 22 to provide a gas flow through the valve which varies with current through the windings 21. At full current the envelope 23 is held in the left-hand end of the chamber 14, as shown by the dotted line.

In Fig. 4, the operation is substantially as described with reference to Fig. 3, except that the ferro-fluid 24 is contained within an annular envelope 23 having inner and outer bores, to provide greater flexibility and a flatter profile, so as to roll in a flatter form along the base of the chamber 14.

In other embodiments of the invention, instead of the envelope 23 rolling along the chamber 14, the envelope 23 and chamber 14 could be shaped in such a way that the magnet 17 forces the envelope 23 to block the passage between the inlet 11 and outlet 12 and application of the electric current modifies the magnetic field so as to distort the envelope 23 in a way which will allow passage of gas.

Other suitable elastomers may be used for the envelope 23 in place of polyurethane.

Claims

1. A fluid-flow control valve including a passage through which the fluid is to flow, a body movable in or across the passage to vary the fluid flow, a volume of ferro-fluid separated by the body from the first mentioned fluid, and an electromagnet arranged when supplied with an electric current to exert a magnetic force on the volume of ferro-fluid and thereby move the body to vary the fluid flow.

2. A control valve, according to Claim 1, in which the body is a diaphragm.

3. A control valve, according to Claim 1 or 2, in which the body is elastomeric.

4. A control valve, according to Claim 3, in which the volume of ferro-fluid is contained in an elastomeric envelope.

5. A control valve, according to Claim 4, in which the ferro-fluid filled envelope is retained within the passage and is caused by the electric current to roll between two positions, in one of which the passage is relatively open for flow of the fluid, and in the other position the passage is partially or completely blocked.

6. A fluid-flow control valve substantially as herein before described with reference to Figs. 1 and 2 of the accompanying drawings.

7. A fluid-flow control valve substantially as hereinbefore described with reference to Fig. 3 of the accompanying drawings.

8. A fluid-flow control valve substantially as herein before described with reference to Fig. 4 of the accompanying drawings.