GB2186721A - Gas-fired cooking appliance - Google Patents

Abstract

A gas-fired cooking appliance (e.g. a hob) has a pivoted cover. A user-operable control valve and a safety cut-off valve (10) control a flow of gas to a burner. Within valve 10, a flap is operated to close the inlet 11 by a push rod connected to the cover, so that gas is turned off whenever the cover is closed. In addition, an electromagnet 21 is energised via switch 23 whenever the (or any of the) operator controlled gas taps is turned on. The electromagnet is effective to latch the flap in the closed condition whenever the cover is closed while a tap is left on, and will not restore the gas supply after opening of the cover until the tap is turned off. This prevents inadvertent escape of gas if the cover was closed without turning off the tap. <IMAGE>

Description

SPECIFICATION Gas-fired cooking appliance This invention relates to a gas-fired cooking appliance and it relates particularly, though not exclusively, to a gas-fired hob fitted with a pivoted cover, displaceable by a user between open and closed positions.

A gas-fired hob forming part of a standalone cooking appliance, or mounted in a existing worktop, is commonly provided with a pivoted cover, sometimes referred to as a 'shut-down" cover. Such covers, which are usually made of toughened glass, or ceramic or metal have an aesthetically pleasing appearance and, in the closed position, provide an additional work surface.

A hob provided with a cover of this kind is usually fitted with a safety cut-off valve effective to interrupt a supply of gas to the burners whenever the cover attains, or approaches, the closed position. This valve ensures that the burners are extinguished even if a user fogets to shut off the supply at a gas tap, and so prevents the cover from being damaged.

In some known arrangements the safety cut-off valve is returned to the open condition whenever the cover is raised. This arrangement could, however, lead to a potentially hazardous situation, particularly if a user leaves a gas tap open inadvertently and then raises the cover so allowing gas to escape unlit.

It is an object of the present invention to provide a gas-fired cooking appliance in which the above-described problems are at least alleviated.

Accordingly there is provided a gas-fired cooking appliance including at least one gas burner; a cover for said at least one gas burner displaceable by a user between open and closed positions; and a user-operable valve and a safety cut-off valve for controlling a supply of gas to said at least one gas burner; wherein said safety cut-off valve has a valve actuator displaceable, in response to closure of the cover, to a first position to block directly a flow of gas past the valve to the at least one burner and being returnable, in response to opening of the cover, to a second position to allow a flow of gas to the at least one burner; and means are provided to releasably latch said valve actuator in said first position, to prevent its return to the second position, whenever both the cover is in the closed position and the user-operable valve is open and until the user-operable valve is closed.

In order that the invention may be carried readily into effect an embodiment thereof is now described by reference to the accompanying drawing which shows a sectional view through a safety cut-off valve.

In one application of the invention a standalone cooking appliance includes a gas-fired hob fitted with a "shut-down" cover, typically made of toughened glass, ceramic or metal.

The cover is mounted pivotally on the hob and displaceable by a user, about a horizontal axis, between a raised open position and a lowered, closed position.

The hob has a number (e.g. four) of gas burners, the gas supply to each being controllable by a respective user-operable valve and by a safety cut-off valve, common to all the burners, positioned on the upstream side of the user-operable valves. The cover is coupled operatively to the safety cut-off valve so as to interrupt a flow of gas to the burners whenever the cover approaches, or attains, the closed position, this arrangement being efective to significantly reduce the risk that the cover is damaged if it is lowered before all the burners have been turned off by the user.

As will be described in greater detail hereinafter, the safety cut-off valve is constructed so that the gas supply to the burners cannot be restored, as a result of the cover being raised, if any one of the user-operable valves has been left open.

As shown in the accompamying drawing, the safety cut-off valve 10 has an inlet duct 11 and an outlet duct 12 coupled respectively to the main gas supply (I) and the user-operable valves (not shown). The safety cut-off valve is fitted internally with a valve actuator in the form of a lever 13 pivoted for displacement about a mounting P, as indicated by the arrows. The lever has a disc 14, of a magnetic material, which, in the shown position of the lever, abuts the mouth of the inlet duct 11 to form therewith a gas-tight seal and thereby block a flow of gas past the valve to the burners. The position of lever 13 is controlled by means of a push rod 15 which can move slidingly, to and fro, within the valve.

The push rod is coupled to the cover by means of a suitable linkage (not shown) so as to push the lever against the inlet duct, to block the supply, whenever the cover is lowered to the closed position. When the cover is raised the push rod is retracted and, provided none of the user-operable valves has been left open, the lever, which is biassed resiliently away from the inlet duct, can return to the position shown in chain-dotted outline allowing gas to flow to the burners.

If, however, one or more of the user-operable valves is left open when the cover has been lowered, a latching arrangement, shown generally at 20, functions to hold lever 13 against the inlet duct, to block the gas supply, even if the cover is subsequently raised, and the latch will not release the lever until all the user-operable valves are closed. It will be appreciated that this arrangement eliminates the risk that gas could escape unlit from a burner solely as a consequence of a user raising the cover when a user-operable valve has been left open inadvertently.

Latching arrangement 20 comprises a solenoid 21 mounted around the inlet duct 11 and connected electrically in series with a source 22 of power and a number of microswitches connected together in parallel. Each microswitch is associated with a respective useroperable valve, though only one of them (23) is shown in the drawing. If any user-operable valve has been left open the associated microswitch 23 assumes the closed state causing power to be supplied to solenoid 21. The solenoid, thus energised, magnetises the inlet duct 11 which is made of a magnetisable material e.g. steel.

If the lever is in the position shown in solid outline, with disc 14 pressed against the mouth of the inlet duct, it will be retained in that position, by magnetic attraction, even if the cover is raised and will only be released from that position if the user-operable valve is closed, thereby causing the microswitch to open and terminating the supply of power to the solenoid.

It will be appreciated that lever 13 need not necessarily be biassed resiliently away from the inlet duct; alternatively, the lever may be allowed to fall away from the inlet duct, unassisted.

It will be appreciated that aithough the present invention has been described with reference to a stand-alone cooking appliance having a hob, the invention is also applicable in other, similar situations in which a gas burner has a user-operable cover and in which it is desirable to prevent gas escaping unlit; for example, in the case of a hob-only appliance or a grill compartment fitted with a fold-down door.

Claims (4)

1. A gas-fired cooking appliance including at least one gas burner; a cover for said at least one gas burner displaceable by a user between open and closed positions; and a user-operable valve and a safety cut-off valve for controlling a supply of gas to said at least one gas burner; wherein said safety cut-off valve has a valve actuator displaceable, in response to closure of the cover, to a first position to block directly a flow of gas past the valve to the at least one burner and being returnable, in response to opening of the cover, to a second position to allow a flow of gas to the at least one burner; and means are provided to releasably latch said valve actuator in said first position, to prevent its return to the second position, whenever both the cover is in the closed position and the user-operable valve is open and until the user-operable valve is closed.

2. A gas-fired cooking appliance according to Claim 1 wherein said latching means includes a solenoid energisable whenever a user-operable valve is open and capable, when energised, of retaining said actuator magnetically in the first position.

3. A gas-fired cooking appliance according to Claim 2 wherein said solenoid is mounted on an inlet duct of the safety cut-off valve which is made of a magnetic material.

4. A gas-fired cooking appliance substantially as hereinbefore described by reference to the accompanying drawing.