GB2235964A - Temperature responsive gas control valve - Google Patents

Abstract

A temperature responsive gas control valve comprises a temperature responsive element 1, an expansion unit 3 coupled to the element 1 which is caused to be expanded when the element 1 is heated, a valve seat 11 disposed between a gas inlet 13 and a gas outlet 14, and a resilient valve member 10 which is rigidly coupled to the expansion unit 3, the valve member 10 being caused to move into sealing contact with the valve seat 11 when the temperature responsive element 1 is heated and being caused to be deformed on continued heating of the temperature responsive element 1 whilst maintaining sealing contact with the valve seat 11. <IMAGE>

Description

Gas Control Valves This invention relates to gas control valves and more particularly to temperature responsive gas control valves for use in gas appliances.

Gas appliances, such as gas fires, are dependent upon an effective flue or chimney and should this flue or chimney become blocked then the products of combustion can enter the room in which the fire is situated. It is now a concern of gas fire manufacturers to find a simple device to overcome this problem and one way is to fit a temperature responsive control such that in the event of a downdraught the flue products heat this control which either shuts the gas off or reduces the flow down to a non-dangerous level. In control valves of this kind, a heat responsive element is arranged to move a normally open valve member against a valve seat. However, some means must be provided for allowing for overt ravel of the valve member until the temperature of the heat responsive element has reached equilibrium.If no such allowance for overtravel is provided, the valve member will be thrust hard against the valve seat and can cause damage and leakage of gas.

The normal method of overcoming this problem is to mount the valve member on a stem in such manner that it can slide along the stem against the pressure of a spring and at the same time prevent leakage of gas at the stem.

It is an object of the present invention to provide a temperature responsive gas control valve with an improved arrangement for allowing for overt ravel of the valve member.

According to the present invention there is provided a temperature responsive gas control valve comprising a temperature responsive element, an expansion unit coupled to said element which is caused to be expanded when said element is heated, a valve seat disposed between a gas inlet and a gas outlet of said valve and a resilient valve member which is rigidly coupled to the expansion unit, said valve member being caused to move into sealing contact with said valve seat when said temperature responsive element is heated, and being caused to be deformed on continued heating of said temperature responsive element whilst maintaining sealing contact with said valve seat.

In a preferred arrangement, it will be arranged that the resilient valve member has an outwardly extending flexible skirt portion which contacts said valve seat, and that the expansion unit comprises a pair of disc shaped elements which are secured together around their circumferences and which are forced apart when said temperature responsive element is heated, the resilient valve member being rigidly coupled to one of the disc shaped elements.

Advantageously, the resilient valve member will be made of synthetic rubber.

An exemplary embodiment of the invention will now be described reference being made to the accompanying drawings, in which: Fig. 1, is a cross-sectional view of a temperature responsive gas control valve in accordance with the present invention, depicted in its normal "open" position; and Fig. 2, depicts part of the valve of Fig. 1 in its "closed" position.

The gas control valve shown in Fig. 1 comprises a temperature responsive element in the form of a hollow bulb 1 connected by capillary tube 2 to an expansion unit 3 constructed from two flexible metal discs 4 and 5 joined together at the circumference to form a completely enclosed unit. Before finally sealing, the bulb 1, capillary tube 2 and expansion unit 3 are filled with a suitable fluid such as water or alcohol depending on the temperature range at which the valve is to operate.

The upper disc 4 has a threaded stem 6 which is threaded through a cover 7 and secured by lock nut 8.

The lower disc 5 has a stem 9 on which is rigidly mounted a resilient, synthetic rubber, valve member 10.

The valve member 10 is disposed above a valve seat 11 which is provided in a valve body 12 between a gas inlet 13 and a gas outlet 14. A small bypass hole 15 is also provided between the gas inlet 13 and gas outlet 14 to determine the minimum flow rate of the valve.

The cover 7 to which the expansion unit 3 is attached is secured to the valve body 12 in a gas tight manner with an interposed gasket 16 such that in the normal unheated condition of the valve, the valve member 10 is spaced from valve seat 11 to permit gas to flow from the gas inlet 13 to the gas outlet 14.

When the bulb 1 is heated, the fluid therein is caused to expand and causes the discs 4 and 5 of the expansion unit 3 to be forced apart. Since disc 4 is fixed relative to the valve body 12, the disc 5 which carries the valve member 10 is caused to move so that the valve member 10 makes sealing contact with the valve seat 11 and cuts off the gas flow between the gas inlet 13 and gas outlet 14, apart from that through the bypass hole 15.

However, the expansion of the fluid in the bulb 1 inevitably continues a short while after the valve has been cut-off and this results in overtravel of the valve member 10 and has the effect of forcing it hard against the valve seat 11. The valve member 10, is made of a resilient, synthetic rubber material and is provided with an outwardly extending skirt portion 17 which is caused to "splay" outwards due to the excess movement of the valve member 10, as is depicted in Fig.

2 of the drawings, whilst maintaining sealing contact with the valve seat 11. In this way no undue pressures are exerted on any part of the control valve.

Adjustment of the temperature at which the gas control valve operates is achieved by adjusting the threaded stem 6 in the cover 7.

Claims (6)

1. A temperature responsive gas control valve comprising a temperature responsive element, an expansion unit coupled to said element which is caused to be expanded when said element is heated, a valve seat disposed between a gas inlet and a gas outlet of said valve and a resilient valve member which is rigidly coupled to the expansion unit, said valve member being caused to move into sealing contact with said valve seat when said temperature responsive element is heated, and being caused to be deformed on continued heating of said temperature responsive element whilst maintaining sealing contact with said valve seat.

2. A valve as claimed in claim 1, in which the resilient valve member has an outwardly extending flexible skirt portion which contacts said valve seat.

3. A valve as claimed in claim 2, in which the expansion unit comprises a pair of disc shaped elements which are secured together around their circumferences and which are forced apart when said temperature responsive element is heated.

4. A valve as claimed in claim 3, in which the resilient valve member is rigidly coupled to one of the disc shaped elements.

5. A valve as claimed in any preceding claim in which the resilient valve member is made of synthetic rubber.

6. A temperature responsive gas control valve substantially as hereinbefore described with reference to the accompanying drawings.

6. A temperature responsive gas control valve substantially as hereinbefore described with reference to the accompanying drawings.

Amendments to the claims have been filed as follows

1. A temperature responsive gas control valve comprising a temperature responsive element, an expansion unit coupled to said element and comprising a pair of disc shaped elements which are secured together around their circumferences and which are forced apart when said temperature responsive element is heated, a valve seat disposed between a gas inlet and a gas outlet of said valve and a resilient valve member which is rigidly coupled to one of said disc shaped elements, said valve member comprising an outwardly extending skirt portion which extends towards said valve seat and which is caused to move into sealing contact with said valve seat when said temperature responsive element is heated, said skirt portion being caused to be deformed on continued heating of said temperature responsive element whilst maintaining sealing contact with said valve seat.

2. A valve as claimed in claim 1, in which the resilient valve member has an outwardly extending flexible skirt portion which contacts said valve seat.

3. A valve as claimed in claim 2, in which the expansion unit comprises a pair of disc shaped elements which are secured together around their circumferences and which are forced apart when said temperature responsive element is heated.

4. A valve as claimed in claim 3, in which the resilient valve member is rigidly coupled to one of-the disc shaped elements.

5. A valve as claimed in any preceding claim in which the resilient valve member is made of synthetic rubber.