GB2182137A - Cookers and hobs - Google Patents

Abstract

A hob or cooker has top heating units which may be gas burners and/or electric hot plates or rings each of which has means (9), e.g. a thermocouple, that respond when the unit is brought into use to hold open a control device supplying gas or electricity to the unit. The operative connection between the responsive means (9) and the control device is interrupted when a lid (8) of the hob or cooker is closed thereby causing the control device to terminate the supply of gas or electricity to the heating unit in the event that the latter has inadvertently been left on as the lid is closed. <IMAGE>

Description

SPECIFICATION Improvements in or relating to cookers and hobs This invention relates to cookers and hobs which may be gas or electric or both. The hob may be an independent unit for mounting in a work surface or it may be part of the cooker.

It is known to fit such hobs and cookers with lids that open to give access to the gas burner and/or el- ectric hot plates or rings. When closed, the lid covers the burners, hot plates or rings thereby protecting the latter and providing a "clean" line to the surface of the hob or cooker.

To allow a userto close the lid when a burner is alight or when a hot plate or ring is energised is extremely dangerous. The heat from the burner, hot plate or ring will damagethe lid and, if the latter isof glass, may well shatterthe lid. Closure ofthe lid may result in extinguishment of the burnerflame and the consequent escape of gas, or alternatively, if the flame is not extinguished, poor combustion of the gasanddamagetothelid.

Safety measures have been proposed which ensure that the supply of gas and/or electricity is automatically cut-off to all the hob burners and/or hot plates and rings when the lid is closed but such measures are not entirely satisfactory.

Accordingly, it is an object of the present invention to provide measures which give a greater certainty of safety than has hitherto been available.

According to the present invention, a hob has one or more gas and/or electric heating units, a lid movable between a fully opened position giving access to the units and a fully closed position preventing such access, and in which there is included, for each unit, a first flow control device for controlling the flow of energy to the unit, means responsive to the operation oftheunitformaintainingthesupplyof energy thereto whilstthe unit is in use, and an arrangementfor disabling the responsive means and so terminating the supply of energy in the eventthatthe lid is moved into its fully closed position with the unit in use, the supply remaining terminated until the lid is re-opened and the responsive means enabled.

Preferably, enabling is effected by operating the first flow control device to an "OFF" position and then to an "enable" position.

The responsive means may comprise a thermally responsive device so located asto respond to heat emitted by the unit when in use.

The thermally responsive device may be operatively connected to a furtherflow control device controlling the supply of energy to the unit.

The thermally responsive device may be a thermocouple and the further flow control device an electromagnetically operated valve energisable by the thermocouple.

The disabling means may comprise a switch operable bythe lid in a mannersuch thatthe switch pre vents energisation of the electromagnetically oper- ated valve when the lid is moved into its fully closed position and permits such energisation when the lid is moved into itsfullyopened position.

The enable position may be such that the electromagnetically operated valve is actuated to a position allowing the flow of energy to the unit.

The thermally responsive device may be a bimetal.

The responsive means may be responsive to the actuation of the first control means and may comprise a resilient device that is stressed when the unit is in use and unstressed when the unit is not in use.

The stressing may occurwhen the first flow con- trol device is operated to the "enable" position.

Actuating means may be provided for releasing the resilient means to operatethefirstflowcontrol device so as to terminate the supply of energy to the unit and in which the lid is linked to the actuating means in such manner as to release the resilient means in the event that the lid is moved to its fully closed position with the unit in use.

Byway of example only, embodiments of the invention will now be described in greater detail with reference to the accompanying drawings of which: Figure lisa diagrammatic perspective view of a hob embodying the invention, Figure2 is an explanatory diagram of a heating unit and control device therefor of the hob shown in Figure 1.

The hob shown in perspective view in Figure 1 comprising a hollow structure 1 which accommodates four heating units 2 which may be gas burners, electric rings or hot plates, infra-red heating units or some other forum of heating unit, or a combination of such units. The heating units are located above a spillagetray 3 on which rests a pan support structure 4.

Each heating unit has a control device operated by a knob 5 located above a control panel 6 for con- trolling energisation ofthe unit.

In the case of gas burners, the knob 5 actuates a gas tap that controls the supply of energy in the form of gaseous fuel from a gas rail located in the hob to a gas supply passageway leading to the burner.

In the case of electric heating units, the knob 5 actuates an electric switch that controls the supply of energyintheform ofelectricityfromelectricity supplyterminalstotheunit.

Where gas burners are used, the hob may also accommodate a gas ignition mechanism which may be controlled by a control button 7 on the control panel 6.

Hinged about a horizontal axis at the rear of the structure lisa lid 8. In Figure 1,the lid is shown in its fully opened position giving access to the heating units and the control panel. The lid is movable by a user to a fully closed position in which it conceals and covers the heating units.

Also located in the structure is a counter-balance mechanism operatively connected to the lid for counterbalancing, in a desired manner, the closing weight of the lid. Examples of such mechanisms are found in U.K. Patent Applications Nos. 2,109,919A, 2,144,845A and 84.24904. Alternatively, the lid may be mounted using a friction pivot.

Yet again, whilst counterbalancing is preferred, it is not essential and the closing weight may not be counterbalanced or resisted in anyway.

Briefly, the invention provides for each unit means associated with the unit which de-energisethe latter in the eventthatthe lid is moved into itsfully closed position whilst the unit is energised, i.e. still in use.

De-energisation is effected by stopping the supply of gas or electricity to the unit. Once de-energised underthe conditions just described,the unit remains de-energised. Beforethe unit can be re-energised, i.e. brought into use, the lid must be opened and the means must be reset by the user.

twill be understood that a unit will usually be deenergised by the user before the latter moves the lid into its fully closed position,the means thus constituting a safety system which ensures that all units are de-energised in the event that the userfailsto effect de-energisation before moving the lid to its fully closed position.

In one embodiment of the invention, each heating unit 1 has associated with it means for indicating when the unit is in use, the means being a thermally responsive device indicated diagrammatically at9 in Figure 1. The devices 9 are so located as to respond to heat emitted by the unit even when the latter is operating at its lowest permitted level of heat output.

Each thermally responsive device is linked to the control device in a manner such thatthe supply of energy is maintained whilstthe unit is in use. The linkage is operatively connected to the lid ion a manner such that movement of the lid into its fully closed position renders the linkage ineffective thereby, in effect, disabling the thermally responsive device so that the latter is unable to maintain the supply of energy to the unit. Thus, should the user inadvertently move the lid into its fully closed position whilst the heating unit is still in use,the latter is de-energised automatically and a hazardous situation is avoided.

As long as the lid remains closed, the supply of energy is interrupted. However, to preventthe restoration ofthesupplywhenthe lid is nextopened, the control device is such that it must be reset by the user before the supply can be restored.

The system is illustrated in Figure 2 which shows a partofthe hob with a heating unitintheform of a gas burner. The thermally responsive device 9 is located close to the burner 1 that is supplied with gaseous fuel via a supply passageway 10 beneath the spillage tray 3. Gas flow from a gas rail 11 to an injector 12 is controlled by a gas tap 13 operable by knob 5. The operative linkage from device 9 to gas tap 13 is represented bythedotted line 14 and includes a device represented by block 15 for rendering the connection ineffective when the lid is moved into its closed position.

The device 9 may comprise a thermocouple whose output is applied via linkage 14, in this case an electrical conductor, to an electromagnetically operated gas flow control valve forming part of tap 13 or associated therewith. Such gas valves are known.

The electricai output of the thermocouple is suf ficientto allow the electromagnet to hold the valve in an open position once the valve is in that position but is insufficient of itself to move the valve from a closed to the open position. The valve is therefore provided with means that enables a user to open the valve and to hold it open until the thermocouple becomes sufficiently hotto provide an output sufficient to hold the valve in its open condition.

The device 15 is, in the case described in the preceding paragraph, a switch that is opened to prevent connection between the thermocouple and the elec tromagnetwhen the lid moves to its closed position and is otherwise closed to permit such connection.

In use, a userfirstopens lid 8to gain access to the burners and control panel. Assuming that all the taps are in the "OFF" position, a user selects the tap appropriate to a burnerto be brought into use, depresses the control knob 5 to open the electromagnetically operated gas valve, ignites gas issuing from the burner and holds the knob depressed fora few seconds until the thermocouple has responded to the gas flame and is able to provide sufficient output to hold the gas valve in its open position. The userthereafter regulates the supply of gas by rotating the knob 5. During this stage, the switch is closed.

If now the user closes the lid without first ensuring that all taps are "OFF", the switch is opened as the lid moves into its closed position and the electrical connection between the thermocouple and electromagnet is broken and the electromagnet is deenergised so allowing the associated gas flow control valve to close.

That vale remains closed and cannot be reopened until the user retu rns the valve to its "OFF" position, opens the lid and then depresses the control knob as described above.

The thermally responsive device may be a bimetal that is mechanically linked to a gas flow control valve associated with the gas tap. In that case, when the lid is closed, the linkage is disabled in a manner such that if the burner is still in use, the gas flow control valve closes. The linkage is then not re-established until the tap has been returned to its "OFF" position.

In another embodiment of the invention, the means responsive to the operation ofthe unit is associated with the control device and responds to the actuation of the latterto indicatewhenthecon- trol device has been actuated to energise a heating unit. The lid is operatively connected to the means in a mannersuch that inthe eventthat a usermovesthe lid into its closed position with the heating unit energised, the control device is actuated by the means to terminatethe supply of energy.

In one example ofthat other embodiment, actuation of a control knob to energise a heating unitfirst stresses a resilient device, for example a spring and then disengages therefrom. Actuation of the control knob to terminate the supply then relieves the resilient device during the final stage of the actuation.

Associated with the resilient device is a latch which serves to hold the device in its stressed condition afterthe control knob has disengaged from the device. The latch is operatively connected with the lid in a manner such that should a user move the lid into its closed position with a heating unit still in use, the latch is released allowing the resilientdeviceto actuate the control device to terminate the supply of energy.

Thus, again, movement of the lid into its closed position with a heating unit still in use does not give rise to hazardous conditions.

Any heating unit still in use when the user moves the lid into its fully closed position is de-energised well before the lid reaches that position. Preferably, de-energisation should be effected at an early stage in the movement of the lid into its closed position.

It will be appreciated that the invention may also be embodied in a hob having both gas and electric heating units.

As an additional indication to a user, a visual or audible warning may be given in the event that a user moves the lid into its fully closed position with at least one heating unit still in operation. The warning may commence as the lid moves from its fully open position and may terminate when the lid reaches its fully closed position. Alternatively, the warning may continue until the user has de-energised all the heating units.

Yetagain,thewarning may commence when a user opens the lid having previously closed the lid with at least one heating unit still in use.

The hob may be part of a cooker. In that case, the control knobs are normally positioned on a control panel located atthe front ofthe cooker.

Claims (15)

1. A hob having one or more gas and/or electric heating units, a lid movable between a fully opened position giving access to the unitorunits and afully closed position preventing such access, and in which there is included, for each unit, a first flow control devicefor controlling the flow ofenergy to the unit, means responsive to the operation of the unit for maintaining the supply of energythereto whilstthe unit is in use, and an arrangement for disabling the responsive means and so terminating the supply of energy in the eventthatthe lid is moved into its fully closed position with the unit in use, the supply remaining terminated until the lid is re-opened and the responsive means enabled.

2. Ahob as claimed in claim 1 in which enabling is effected by operating the first flow control device to an "OFF" position and then to an "enable" position.

3. A hob as claimed in claim 1 or 2 in which the responsive means includes a thermally responsive device so located as to respond to heat emitted by the unit when in use.

4. A hob as claimed in claim 3 in which the thermally responsive device may be operatively connected to a further flow control device controlling the supply of energy to the unit.

5. A hob as claimed in claim 4 in which thethermally responsive device is a thermocouple and the furtherflowcontrol device is an electromag netically operated valve energisable by the thermocouple.

6. A hob as claimed in claim 5 in which the disabl- ing means comprises a switch operable by the lid in a manner such that the switch prevents energisation ofthe electromagnetically operated valve when the lid is moved into its fully closed position and permits such energisation when the lid is moved into its fully opened position.

7. A hob as claimed in claim 6 in which the enable position is such that the electromagnetically operated valve is actuated to a position allowing the flow of energy to the unit.

8. A hob as claimed in claim 3 in which thethermally responsive device is a bimetal.

9. A hob as claimed in claim 1 or 2 in which the responsive means responds to the actuation of the first control device.

10. A hob as claimed in claim 9 in which the responsive means comprises a resilient device stressed when the unit is in use and unstressed when the unit is not in use.

11. A hob as claimed in claim lOin which stres- sing occurs when the first flow control device is operated to the "enable" position.

12. A hob as claimed in claim 10 or 11 in which actuating means are provided for releasing the resilient means to operate the first flow control device so as to terminate the supply of energy to the unit and in which the lid is linked to the actuating means in such manner as to release the resilient means in the eventthatthe lid is moved to its fully closed posi- tion with the unit in use.

13. Ahobasclaimed in claim 1 substantiallyas herein described.

14. A hob substantially as herein described with reference to and as illustrated by Figures 1 and 2 of the accompanying drawings.

15. A cooker including a hob as claimed in any one of the preceding claims.