GB2184520A - Gas valves - Google Patents

Abstract

A control valve assembly for a gas cooker having a lid to close down onto the burners when out of use, has a valve 28, 24, 22, closable by the lowered lid to prevent gas flow from inlet 10 to outlet 12 leading to the taps through main throat 16 and bleed passage 40, so as to terminate the burner flames when the lid is down, and a valve 30 to prevent the gas flow being re-established when the lid is lifted if any of the appliance taps have been left on. Valve 30 is held open by mains gas pressure, and closed by spring 36 if pressure on the outlet side acting on enlarged area 32, 34 falls towards ambient atmospheric pressure, for example because a tap is left on. When the tap is closed, bleed via passage 40 builds up pressure on area 32, 34 so that together with pressure within throat 16 the valve 30 is re-opened. <IMAGE>

Description

SPECIFICATION Gas valves This invention relates to gas valves used with gas cookers of the kind having a lid which can be moved to a closed position over the hob. This isto provide extra working surface at times when the cooker hob is not in use, or for aesthetic purposes.

With such cookers, it is normal to use a valve in the gas supply system, having a part which is displaced by the lid so that when the lid is in the closed position, the gas supply is cut off, and vice versa. The primary object of this device is to prevent gas being turned on accidentally whilst the lid is lowered. But an unwanted side effect of the device isthat ifthe lid is lowered when a burner is lit but turned low, the flame will be extinguished butthegassupplywill be restored perhaps unexpectedly and unrecognised, when the lid is reopened. The object of the present invention is to provide a valve which avoids this possibility.

According to the invention, a valve for control ling the supply of gas to one or more taps comprises a throat for main gas flow, first and second valvesfor controlling the flow through said throat, the first valve being mechanically displaceable between open and closed positions, and the second valve being spring displaced to a closed position and automaticallyopened, said second valve having an area largerthan that ofthethroat and being subject two gas pressure in the outlet passage leading to said taps, and a bleed passage controllable by said first valve and not by the second valve, whereby ordinary gas pressure acting on said second valve in said throat alone is insufficient to overcome the spring and open the valve, but said ordinary pressure plus pressure bled to the outlet passage and accumulated therein is sufficient to overcome said second valve.

Hence, if any of the taps is left in an on position when the lid is closed, causing the mechanical displacement of the first valve to cut off the gas supply, the fall in pressure in thevalve outlet due to atap being on will allow the spring to displace the second valve to a closed position. When the lid is reopened, the open tap will prevent pressure accumulating (via the bleed passage) to act upon the second valve area outside the throat, so that the spring will hold it closed. It is necessaryto turn off the tap which had been left on, so that pressure can accumulate in the passage until it is sufficient, plus the force derived from the pressure acting within the throat, to overcome the spring and restore gas flow, whereupon the tap may be turned on and the burnerrelit.

One embodiment ofthe invention is described with reference to the accompanying drawing wherein the sole figure is an elevation of a valve ac- cording to the invention.

In the drawing, the valve body is provided with an inlet 10 and an outlet 12 separated by a divider 14 with a throat 16 for-flowthrough the divider. One end ofthe throat is provided with a valve seat 18 and the other witch a valve seat 20.

Afirstvalve 22 is for closing seat 18 and is mounted on one end of a stem 24 urged by spring 26 to a position in which the part 28 projects from the valve body and valve 22 is held offits seatto allow gas flow. Part 28 will be arranged on the cooker so that it is displaced against the spring when the lid is lowered to close the burners and hence cut off the gas supply.

At the other end of the throat, closure member 30 is provided on an enlarged area valve part 32 supported on a sealing diaphragm 34. Spring 36 urges that valveto a closed position, and can be preset byan adjusterscrew38. Bleed passage 40 bypassesthe throat 16, and is closed by the valve 22 when the latter is in a closed position but is not closed bythe valve 30 when that is in a closed position.

The drawing shows the parts in the open position when the lid is raised. The parts remain in this position whether any burners are lit or not, and whether anytapsareturned on or not.

When the lid is lowered to close off the burners, part 28 is actuated and valve 22 closes on seat 18. If all of the taps are off atthattime, the valve 30 will remain open. When the lid is reopened, the valve 22 will reopen and cooker operation can continue.

However, if valve 22 seats and any tap is leftturned on, the gas supply is terminated by the valve 22 and pressure in outlet 12 will fall allowing spring 36to close valve 20. If the lid is then reopened, valve 22 is opened but valve 30 remains closed. The main gas pressure acting within the throat on the area of valve 30 exposed to that pressure is insufficient to overcome the spring 36 on its own. However, gas bleeds through the passage 40, but if there is one or more gas taps on,therewill be no buildup of pressure in the outlet 12 and hence the area of the part 32 outside the throatwill be exposed to ordinary atmosphere pressure or very little more.When the user realises that turning the tap on is not producing a gas flow, and goes on to turn all ofthetaps off, pressurewill build up in the outlet 12 via the bleed passage 40 until that pressure acting on the valve 32 plus the pressure acting on the smaller area within the throat 16 will overcomethespring,valve32will open and ordinary cooker operation can recommence.

1. Avalveforcontrolling the supply of gas to one or more taps comprising a throat for main gasflow, first and second valves for controlling the flow through said throat, the first valve being mechanic ally displaceable between open and closed positions, and the second valve being spring displaced to a closed position, said second valve having an area largerthan that of the throat and being subject to gas pressure in the outlet passage leading to said taps, and a bleed passage controllable by said first valve and not by the second valve, whereby ordinary gas pressure acting in said throat alone on said second valve is insufficient to overcome the spring and open the valve, but said ordinary pressure plus pressure bled to the outlet passage and accumulated therein to act upon said area largerthan the throat is col- lectively sufficient to overcome said spring and open the second valve.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (6)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Gas valves This invention relates to gas valves used with gas cookers of the kind having a lid which can be moved to a closed position over the hob. This isto provide extra working surface at times when the cooker hob is not in use, or for aesthetic purposes. With such cookers, it is normal to use a valve in the gas supply system, having a part which is displaced by the lid so that when the lid is in the closed position, the gas supply is cut off, and vice versa. The primary object of this device is to prevent gas being turned on accidentally whilst the lid is lowered. But an unwanted side effect of the device isthat ifthe lid is lowered when a burner is lit but turned low, the flame will be extinguished butthegassupplywill be restored perhaps unexpectedly and unrecognised, when the lid is reopened. The object of the present invention is to provide a valve which avoids this possibility. According to the invention, a valve for control ling the supply of gas to one or more taps comprises a throat for main gas flow, first and second valvesfor controlling the flow through said throat, the first valve being mechanically displaceable between open and closed positions, and the second valve being spring displaced to a closed position and automaticallyopened, said second valve having an area largerthan that ofthethroat and being subject two gas pressure in the outlet passage leading to said taps, and a bleed passage controllable by said first valve and not by the second valve, whereby ordinary gas pressure acting on said second valve in said throat alone is insufficient to overcome the spring and open the valve, but said ordinary pressure plus pressure bled to the outlet passage and accumulated therein is sufficient to overcome said second valve. Hence, if any of the taps is left in an on position when the lid is closed, causing the mechanical displacement of the first valve to cut off the gas supply, the fall in pressure in thevalve outlet due to atap being on will allow the spring to displace the second valve to a closed position. When the lid is reopened, the open tap will prevent pressure accumulating (via the bleed passage) to act upon the second valve area outside the throat, so that the spring will hold it closed. It is necessaryto turn off the tap which had been left on, so that pressure can accumulate in the passage until it is sufficient, plus the force derived from the pressure acting within the throat, to overcome the spring and restore gas flow, whereupon the tap may be turned on and the burnerrelit. One embodiment ofthe invention is described with reference to the accompanying drawing wherein the sole figure is an elevation of a valve ac- cording to the invention. In the drawing, the valve body is provided with an inlet 10 and an outlet 12 separated by a divider 14 with a throat 16 for-flowthrough the divider. One end ofthe throat is provided with a valve seat 18 and the other witch a valve seat 20. Afirstvalve 22 is for closing seat 18 and is mounted on one end of a stem 24 urged by spring 26 to a position in which the part 28 projects from the valve body and valve 22 is held offits seatto allow gas flow. Part 28 will be arranged on the cooker so that it is displaced against the spring when the lid is lowered to close the burners and hence cut off the gas supply. At the other end of the throat, closure member 30 is provided on an enlarged area valve part 32 supported on a sealing diaphragm 34. Spring 36 urges that valveto a closed position, and can be preset byan adjusterscrew38. Bleed passage 40 bypassesthe throat 16, and is closed by the valve 22 when the latter is in a closed position but is not closed bythe valve 30 when that is in a closed position. The drawing shows the parts in the open position when the lid is raised. The parts remain in this position whether any burners are lit or not, and whether anytapsareturned on or not. When the lid is lowered to close off the burners, part 28 is actuated and valve 22 closes on seat 18. If all of the taps are off atthattime, the valve 30 will remain open. When the lid is reopened, the valve 22 will reopen and cooker operation can continue. However, if valve 22 seats and any tap is leftturned on, the gas supply is terminated by the valve 22 and pressure in outlet 12 will fall allowing spring 36to close valve 20. If the lid is then reopened, valve 22 is opened but valve 30 remains closed. The main gas pressure acting within the throat on the area of valve 30 exposed to that pressure is insufficient to overcome the spring 36 on its own. However, gas bleeds through the passage 40, but if there is one or more gas taps on,therewill be no buildup of pressure in the outlet 12 and hence the area of the part 32 outside the throatwill be exposed to ordinary atmosphere pressure or very little more.When the user realises that turning the tap on is not producing a gas flow, and goes on to turn all ofthetaps off, pressurewill build up in the outlet 12 via the bleed passage 40 until that pressure acting on the valve 32 plus the pressure acting on the smaller area within the throat 16 will overcomethespring,valve32will open and ordinary cooker operation can recommence. CLAIMS

1. Avalveforcontrolling the supply of gas to one or more taps comprising a throat for main gasflow, first and second valves for controlling the flow through said throat, the first valve being mechanic ally displaceable between open and closed positions, and the second valve being spring displaced to a closed position, said second valve having an area largerthan that of the throat and being subject to gas pressure in the outlet passage leading to said taps, and a bleed passage controllable by said first valve and not by the second valve, whereby ordinary gas pressure acting in said throat alone on said second valve is insufficient to overcome the spring and open the valve, but said ordinary pressure plus pressure bled to the outlet passage and accumulated therein to act upon said area largerthan the throat is col- lectively sufficient to overcome said spring and open the second valve.

2. Avalve as claimed in Claim 1 wherein said first and second valves are co-axial and operate on opposite ends of said throat.

3. A valve as claimed in Claim 1 orClaim2 wherein said first valve is mounted on a stem projecting to the exterior ofthe body of the valve, for displacement as by a cooker lid being closed, and is spring urged to the projecting position in which the first valve is open and the bleed passage is also open.

4. A valve as claimed in any of Claims 1 to 3 wherein said second valve comprises a closure area for sealing on the throatto close the same but leave the bleed passage open, a larger area part associated with the closure area, and a sealing diaphragm supporting the larger area part.

5. A valve as claimed in Claim 4wherein the spr- ing pressure on the second valve is adjustable.

6. A valve for controlling the supply of gas to one or more taps, substantially as described, with reference to the accompanying drawings.