GB2182136A - Improvements in or relating to cooking hobs - Google Patents

Abstract

A cooking hob accomodates top heating units e.g. burners and a lid movable between a fully opened position giving access to the burners and a closed position covering the burners. Associated with each of the gas taps is a switch that is closed when the associated tap is turned 'ON'. Another switch is closed when the lid is in a predetermined position, e.g. fully opened and closure of the two switches energises an electromagnet which operates a lid lock which prevents movement of the lid unless the 'ON' tap is turned off. Alternatively, the lid may be held in its fully opened position by a mechanism linked to the gas taps and which prevents movement of the lid from its fully opened position unless all the taps are 'OFF'.

Description

SPECIFICATION Improvements in or relating to cooking appliances This invention relates to cooking appliances for example hobs which may be gas and/orelectric. The hob may be an independent unit for mounting in a work surface or it may be part of a cooker.

It is known to fit such hobs and cookers with lids that open to give access to thetop heating unit which may be gas burners and/or electric 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 ofthe hob or cooker.

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

Safety measures have been proposed which ensurethatthe supply of gas and/or electricity is automatically cut-offto all the hob burners and/or hot plates and rings when the lid is closed butsuch measures are not entirely satisfactory.

According to the present invention, there is provided a cooking appliance comprising a hob accommodating one or more heating units and having a lid movable between a fully opened position giving access to the or each heating unit and afully closed position in which such access is prevented, and, forthe or each heating unit, a first control device for controlling the supply of energy to the unit, each such first device having an "OFF" condition when the unit is de-energised, and in which means are provided for preventing movement ofthe lid from a predetermined position unless the or each first control device is in the "OFF" condition.

Additionally, the invention also provides a cooking appliance comprising a hob accommodating one or more top heating units and having a lid movable between a fully opened position giving access to the top heating unit or units and a closed position in which such access is prevented, and,forthe or each top heating unitafirstcontrol deviceforcontrolling the supply of energy to the unit, each such first device having an "OFF" condition when the unit is de-energised, and in which means are provided for preventing movementofthe lid from itsfullyopened position unless the or each first control device is in its "OFF" condition.

Furthermore, the invention also provides a cooking appliance accommodating one or more top heating units and having a lid movable between a fully opened position giving access to the or each top unit and a fully closed position in which such access is prevented, and,forthe oreach top unit a first control device for controlling the supply of energy to the unit, each such device having an "OFF" condition when the unit is de-energised, and a further control deviceforcontrolling the supply of energy to the or each firstflow control device, the further control device being actuable by the movementofthe lid in a manner such that the further device is actuated to prevent the supply of energy when the lid reaches an intermediate position between its fully opened and fully closed positions and to maintain such prevention at all positions of the lid from the intermediate to the fully closed position while at all other positions of the lid such supply is permitted, and in which means are provided for preventing movement ofthe lid from it fully closed position unless all the or each first control device is in its "OFF" condition.

The present invention also provides a cooking appliance comprising a hob accommodating one or more top heating units and having a lid movable between a fully opened position giving access to the or each top unit and afullyclosed position in which such access is prevented, and, for the or each top unit a first control device for controlling the supply of energy to the unit, the or each control device having an "OFF" condition when the unit is de-energised, and, a further control device for controlling the supply of energy to the or each first control device, the further control device being actuable by the lid in a mannersuch thatthefurther device is actuated to prevent the supply of energy when the lid reaches an intermediate position between its fully opened and fully closed position while in all other positions ofthe lid such supply is permitted, and in which means are provided for preventing movement of the lid from a predetermined position between the fully closed position and the intermediate position to the intermediate position unless the or each first control device is in its "OFF" condition.

Further means may be provided for inhibiting the movement preventing means except when the lid is in the predetermined position or in its fully opened or its fully closed position.

Means may be provided for sensing the condition ofthe or each heating unit to determine whetherthe respective first control device is in its "OFF" condition,the sensing means being operatively connected to the movement preventing means in such manner as to inhibit operation of the latter means only when the device is in its "OFF" condition.

Alternatively, means may be provided for sensing the condition of the or each first control device to determine whether the device is in its "OFF" condition, the sensing means being operatively connected to the movement preventing means in such mannerastoinhibittheoperationofthelatter means only when the device is in its "OFF" condition.

The movement preventing means comprises an electromagnet.

The electromagnet may comprise an armature adapted to lockthe lid in the predetermined position orto prevent movement ofthe lid from that position.

Means may be provided for permitting energisation ofthe electromagnet when the lid is in the predetermined position and at least one of the first control devices is not in its "OFF" condition.

The means permitting energisation may comprise a first switch operable to a closed condition when the lid is in its predetermined position and further switches each of which is associated with a different one ofthefirstcontrol devices and is operable thereby to a closed condition when the first device is not in its "OFF" condition.

The first switch may be operable buy a cam movable with the lid.

Each first control device may include a cam for operating its associated switch.

Alternatively, the movement preventing means may include a linkage operable on movement of a first control device from an "OFF" condition.

The linkage may comprise a member common to all the first control devices and is movable thereby when any of the first control devices is operated from its "OFF" condition.

Each first control device may incorporate an arrangement for moving the member when the control device is operated from its "OFF" condition unless the slide member has previously been moved by operation of another first control device from its "OFF" condition.

Each first control device may incorporate a pinion and the slide member includes, for each first control device, a rack operable bythe pinion of the control device to move the slide member when the first control device is operated from its "OFF" condition.

The rack may be movable relativelyto the slide memberwithin limits defined by the latter.

Each rack may be mounted in an aperture in the member and in which the extent of the aperture defines the limits of movement of the rack.

Means may be provided for locking the linkage againstmovementwhenthe lid is in its closed position.

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 perspective schematic view of a hob incorporating the invention, Figure2 is a circuit of an energising control of a first embodiment ofthe invention, Figures 3, 4and 5are schematic representations of details of the first embodiment, Figure 6 is a perspective view of a part of a hob embodying the invention, Figure 7 is a section of a component used in one embodiment of the invention, Figure 8 is a perspective view of part of a second embodiment of the invention, Figures9and 10areexplanatorydiagrams,and Figure 11 is a perspective view of part of a third embodiment ofthe invention.

The hob shown in perspective view in Figure 1 comprises a hollow structure 1 which accommodates four top heating units 2 which may be gas burners, electric rings or hot plates, infra-red heating u nits or some other form of heating unit, or a combination of some or all ofthose units. The heating units are located above a spillage tray 3 on which rest a pan supportstructure4.

Each top heating unit has a control device operated by a knob 5 located above a control panel 6 for controlling energisation ofthe unit.

In the case oftop 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 hobto a gaseous fuel supply passageway leading to the burner.

In the case oftop electric heating units, the knob 5 actuates an electric switch that controls the supply of energyintheform ofelectricityfromelectricity supply terminals to the unit.

Where gas burners are incorporated, the hob may also accommodate gas ignition mechanism which may be controlled byacontrol button7onthe control panel 6, each burner having an igniter9.

Hinged about a horizontal axis at the rear ofthe structure lisa lid 8. In Figure 1,the lid is shown in its fully opened position giving accessto thetop 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 top heating units and the control panel.

Also located in the structure is a counterbalance mechanism operatively connected to the lid for counterbalancing, in a desired manner, the closing weight ofthe lid. Examples of such mechanism are found in U.K. Patent Applications Nos. 2,109,919A and 2,1 44,845A 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 any way.

Broadly speaking, the present invention provides means which prevent movement ofthe lid from a predetermined position unless all top heating units are out of use. Associated with each top unit orwith the first control device thereof is a sensor which is able to detectwhetherthe unit is in use and the condition of the sensor is then used to determine whether two operate the means to prevent movement ofthe lid.

Additionally, there may be included a further sensor responsive to the lid position and which is so arranged that it inhibits operation of the means by any ofthe first sensors unless the lid is in the predetermined position. Such an arrangement ensures that the lid is in the correct position in which it can be locked.

The predetermined position may be the fully-opened position, the fully closed position or an intermediate position between the fully opened and fully-closed positions.

Where movement of the lid from the fully-closed or intermediate position is prevented, a further control device is provided that is actuated by the lid and which prevents the supply of energy to the first mentioned device or devices when the lid, during a closing movement, passes beyond the intermediate position. The supply of energy is permitted by the further control device when, during an opening movement, the lid passes beyond the intermediate position.

The means may comprise a locking arrangement which actually holds the lid in the predetermined position or it may comprise an arrangement which prevents movement of the lid from that position but does not actually "lock" the lid in that position.

Figure 2 is the energising circuit of an electromagnetwhose operating coil is shown at 10.

Switch S1 is operated in response to movement of the lid 8 and is closed only when the lid is in its fully opened position. Parallel-connected switches S2 S5are each associated with one of the first control devices that control the supply of energy to the top heating units and each is closed when thetop heating unit is brought into use by operation ofthe appropriate control knob, that is, when the first control device is operated from its "OFF" condition.

Thus, when the lid 8 is in its fully opened position, switch S1 is closed. If now one of the control devices is operated to energise a heating unit, one ofthe switches in the groups S2...S5 is closed and coil 10 is energised and this actuates a lid lockto a position in which it engages the lid and prevents movement thereof from the fully opened position.

Figure 3 shows the electromagnet in schematic form and referenced 11. The armature of the electromagnet is a lever 1 la pivotally mounted at 1 1b and formed with an extension 11 cwhich when the coil 10 is energ ised moves into engagement with the lid 8 and prevents movement ofthe latterfrom the fully opened position. The lever 1 1a is arranged so that, on de-energisation of the electromagnet, it returns to its original position under gravity, although a spring return may be used if desired.

Figure 4 shows in schematicform only one way in which switch S1 may be operated. The lid 8 carries a cam 12that rotates about the pivotal axis 13 ofthe lid as the latter moves. The cam 12 is profiled in a manner such that when the lid in is in itsfullyopened position, the swisth S1 represented in Figure 4 by block 14 is closed, the switch operating lever 15 being allowed to move upwardly bythe cutaway 16 ofthe cam under the action of a restoring spring in the switch. Once the lid is moved from its fully opened position, lever 15 is depressed by the raised portion 17 ofthe cam profile and the switch is opened.

Figure 5shows, in diagrammaticform,afirst control device 1 8with an operating spindle 19 carrying a cam 20 that actuates the respective one of the switches S2...S5 when the control unit is actuated by rotating the spindle 19 to energise the associated heating unit. The switch contains a restoring spring which ensures that the switch returns to its open position when the control device is actuated to de-energisethe heating unit.

Thus, in use, assuming that the lid 8 is closed and all top heating units are d-energised or "OFF",the userfirst lifts the lid 8to itsfullyopened position and when the lid reaches that position, switch S1 closes.

Atop heating unit is now brought into use by operation of the associated first control device and one of the switches S2...S5 closes thereby completing the energising circuitforthecoil 10 and the electromagnet pivots lever 12 and extension 13 locks the lid so preventing movementthereoffrom thefullyopened position.

At the end of a cooking operation, the userwill turn offthetop heating unit or units that have been used and this opens the previously closed switches ofthe group S2...S5 so breaking the energising circuit of the coil 10 releasing the lever and moving the extension 13 out of the path of closing movementof the lid so that the user is able to close the lid.

However, if inadvertently one or more of the top heating units is left on, the lid cannot be moved from its fully opened position until all the heating units have been turned "OFF" by means of the respective control units.

Figure 6 is a perspective view of part of a hob showing one way of arranging the components shown in Figures 2-4 in a hob.

Figure 6 shows the cam 17 mounted upon the pivotal axis 13 ofthe lid 8 and secured to the lid for movement therewith. The cam 17 is formed with a cut-away 16 which co-acts with the operating lever 15 of switch S1 shown as a block 14. Electromagnet 11 is mounted upon the rearwall ofthe hob in a position adjacent to the cam 17 so that the extension 1 it of the lever 11 a moves, when the electromagnet 11 is energised, into the path of movement of cam 17 and contacts surface 1 7a thereof as soon as the lid 8 is moved from thefully opened position shown in Figure 6.

Figure 6 also shows a control unit 18 into which is builtthecam 20 shown in Figure 5. The unit 18 is one of several such control units each of which incorporates one of the switches S2-S5.

Electromagnet 11, switch S1, switch S2 (S3...S5) are series connected in the manner shown in Figure2 across the mains supply.

If all the control units 18 are in the fully "OFF" condition none of the switches S2...S5 is energised and the user is able to close the lid from the open position shown in Figure 6. However, if one or more ofthe control units is not in its fully "OFF" condition then the associated one of the switches S2...S5 will be closed, the electromagnet 11 will beenergised and the lever 1 lawill pivotto bring the extension 1 Ic into the path of movement of the surface 1 7a ofthe cam 17 and prevent movementofthe lid from itsfully opened position. Thus, a potentially dangerous situation is avoided and the user is alerted to the fact that at least one of the control units 18 is not in its fully "OFF" condition.

Once the user has returned to its fully "OFF" condition any control unit not in that condition, the electromagnet 11 will be de-energised. Lever 1 1a pivots and extension 11 c moves out of the path ofthe surface 17a and the lid 8 can be moved from itsfully open position.

It will be appreciated that the state of a top heating unit may be sensed in other ways than sensing the state of the associated control device. For example, each top heating unit may include a thermally responsive sensor exposed to heat emitted bythe unit. That state of that sensor, which may, for example, be a bimetal, is then used to operate a switch in the group S2...S5.

Inthecaseof a gas burner,thethermally responsive element will sense the presence of a flame at the burnerandwill respond rapidllywhen the flame is extinguished.

In the case of electric heating units having a considerable thermal capacity particularly if they are of the hot plate type, there will be a delay before the unit reaches a temperature at which the sensorwill operatetheswitch.Thisdelaywill ensurethatthelid can be closed only when the unit reaches a temperature at which it will not damage the lid when closed.

In the case of a cooker, cam 17 can be so orientated that it closes switch S1 when the lid is in itsfully closed position, extension 13 then being positioned, on energisation of coil 10 in the event that one or more of switches S2...S5 is closed, to prevent movement of the lid from its fully closed position.

With cookers, the knobs of the control devices ofthe top units are accessible to a user even when the lid is closed.With a hob,the hob lid, when closed, normally prevents user access to the control knobs.

In that case, the cooker also incorporates a lid operated further control device, a valve in the case of gaseous fuel and a switch in the case ofelectrical energy, which, when the lid, on moving from its fully opened position to its fully closed position, passes a certain intermediate position, is actuated to prevent the supply of energy to the control device controlling the supply of energy to the heating units. The supply of energy is restored when, during an opening movementofthe lid,the latter passes the intermediate position provided that all the first control devices are in an "OFF" condition.

Alternatively, the cam 17 may be so orientated that it closes switch S1 just before the lid, during an opening movement, reaches the intermediate position. In this case, opening movement ofthe lid to the intermediate position and beyond is prevented in the eventthat one or more ofthe switches S2-S5 is closed, and thefurther control device cannot be actuated to permit supply of energy to the control devices controlling the supplyofenergytothetop units.

Thus, in the first alternative, the user cannot open the lid to gain access to thetop heating units unless all the latter are de-energised. lfthe user finds that the lid is locked, a check must be made on the control devices controlling the supply of energy to the top heating units and any not in the "OFF" condition must be returned to that condition.

Similarly, in the second alternative, the user cannot open the lid to a position in which energy supply to the control devices controlling the supply of energy to the top units unless all those units are de-energised. If the user finds that movement ofthe lid to the fully opened position is prevented, a check must be made as before and the appropriate action taken to ensurethat all the respective control devices are in the "OFF" condition.

Lid-operated further control devices are described in U.K. PatentApplication Nos. 2,109,91 9A and 2,144,845Ato which reference should be made for further details.

Whilstthe lid-operated further control devices described in the Applications referred to in the preceding paragraph are in effect simple open/shut valves, other forms offurthercontrol device can be used.

For example, the further control device may be such that supply of energy is restored to the first control devices of the top heating units only when those devices are in an "OFF" condition.

Such a further control device is shown in schematicform in Figure 7.

The further control device shown in Figure 7 is a gas control valve with a valve 21 mounted in a body 22 having a gas inlet 23 and gas outlet 24. The valve 21 is secured to a spindle 25 which also carries a diaphragm 26 clamped in a gas-tight manner in body 22 by means of a top cover 27. The diaphragm 26 carries a disc 28 and the valve 21 is urged towards its seat by a spring 29 disposed between the disc 28 and the cover 27.

Mounted on the cover 27 is a bracket 30which forms a bearing for spindle 31 which is operated in a linear manner by the action of opening and closing the lid ofthe hob (not shown).

The bracket 30 also carries a leaf spring 32 with pad 33. This spring is biassed such that when free (solid lines) it leaves space for the valve spindle 25to lift.

When the rod 31 is moved forward as the result of the lid ofthe hob being closed, the conical portion rides against spring 32 and moves it in a downward direction to cause padd 33 to press on spindle 25 (dotted lines) and mechanically hold valve 21 on its seat.

In body 22 is a small weep passage34between inlet 23 and outlet 24.

The action ofthe valve is asfollows: Gas enters thevalve at inlet 23 and cannot passto outlet 24when valve 21 is on its seat exceptforthe small weep passage 34. Ifthe lid ofthe gas hob in which the control valve is fitted is closed, the valve is mechanically held on its seat by rod 31 as explained above. If a gas tap of a top burner has been left "ON", the action of closing the lid will shut off the gas (the small supplythrough the weep passage is not significant and not dangerous). If the lid is raised whilst the tap is still " ON ", the pressure of gas over the small area of valve 21 is insufficientto lift it againstthe pressure of spring 29.

When the top is closed, the small weep of gas through weep passage 34 builds up pressure in outlet 24 and under diaphragm 26 which, dueto its large area, gives a lifting force sufficient to overcome spring 32 and the valve 1 is lifted, thereby restoring gas flow to the gas outlet 24.

Such an arrangement provides an additional safeguard in the event that, for some reason, the user isabletomovethelidfrom its predetermined position without all the first control devices ofthetop heating units being in an "OFF" condition. The supply of gas will not be fully restored until all the taps are in an "OFF" condition.

Equally, the state ofthetop heating unit may be indicated mechanically by, for example, sensing mechanically the state ofthe associated control device.

Figures 8 and 11 are respective views of embodiments ofthe invention employing mechanical sensing ofthe state of the control devices.

Figure 8 is a perspective of part of a hob 1 with the spillagetrayand some other parts removed. The hob is a gas hob in which the structure ofthe hob accommodates a gas rail 35 secured in some suitable manner in the structure 1,for example as shown in Figure 8 to the side wall ofthe structure.

Mounted upon the gss rail are first control devices in the form of gas taps 36 that control the supply of gas from a gas supply passage inside the rail to injectors 37 which, in turn,feed into the gaseous fuel supply passages, referred to above, of the top gas burners in the hob. The gas rail 35 extends to the rear ofthe structure 1 and is there joined to a gas supply conduit (not shown) leading from a gas main.

Each gas tap has an upwardly extending control spindle 38 on which a control knob is located. One such knob is shown at39.

Each tap includes a niting arrangement which holds the tap locked in its "OFF" condition until the spindle is depressed inwardly after which the spindle can be rotated to a required "ON" condition.

Examples of such valves are found in U.K. Patent Application No. 2,129,097A.

Mounted upon the gas rail 35 and secured thereto so asto extend over the upper ends ofthe gas taps 36 is an elongate plate 40 apertured at spaced positions 41 along its length to permit passage ofthe spindles 38.

Resting upon the upper surface ofthe plate 40 and movable along that surface is a spring plate 42 having rectangular apertures 43 through which extend the control spindles 38 of the taps 36.

On one ofthe longer edges of each aperture is positioned a rack member 44 whose base is slotted as at 45 to fit overthat edge and allowthe rack member to slide along the edge. The length ofthe rack 44 is less than that of the edge on which it is mounted. The racks 44 each co-operate with a pinion 46 forming partofa respective control knob 39on each ofthe spindles 38. Only one such knob is shown in Figure 8. The opposite edge of each aperture43 supports a bearing strip 47 which holds pinion 46 of the control knob 39 in mesh with the rack44. With the taps in the "OFF" conditions, the racks 44 abutthe left-hand edges of the apertures 43.

Spring plate 42 is biassed to the right as viewed in Figure 8 by a spring 48.

That end of spring plate 42 remote from spring 48 is apertured as shown at 49 and one end 50 of a lever is located in the aperture. The lever is pivotally mounted inside a housing 51 in a rearcornerofthe structure 1 and its other end is located adjacent the path of movement of the lower edge ofthe lid 8 and is movable into that path ata point at which it locksthe lid in its fully opened position or prevents movement ofthe lid therefrom as will now be described.

Assuming thatthe lid 8 is closed, a userwishingto use a top burner first lifts the lid 8to gain access to the knobs 39. The knob appropriate to the required top burner is rotated to an "ON" condition and gas issuing from the burner is ignited.

The positions of the spring plate 42 and the racks 44 are then as shown in Figure 9 assuming that it is the left-hand (as seen in Figure 9) knob that has been rotated. It will be observed that rotation of the left-hand control knob has moved the spring plate to the left by virtue of the engagement of the left-hand end ofthe rack with the left-hand end of the aperture 43.

Movement to the left (as seen in Figure 9) ofthe spring plate42 occurs againsttheaction ofthespring 48. That movement of the spring plate 42 pivots the lever by acting on end 50 thereof and this movesthe lever into its lid locking position or into a position preventing movement ofthe lid.

The movement to the left ofthe spring plate 42 does not result in rotation of any other control knob because such knobs are held against rotation by the niting arrangement included in the taps. The result is that the spring plate moves relatively to the racks of the other control knob, those racks then being located at the other ends of the respective apertures as is shown by the right-hand rack in Figure 9.

Movement ofthe lid from its fully opened position is thus prevented unless the userfirstturns off the top gas burner in use by rotating to its "OFF" condition the associated control knob. That rotation allows spring plate 42 to movetothe rightunder spring 48 thus pivoting the lever in the reverse direction and returning itto its "non-locking" position.This position is shown in Figure 10 and it will be observed that the rack of the right-hand knob has slid along the aperture and is now in engagement with the left-hand end of the associated aperture.

If more than one top gas burner is in use, no movement ofthe spring plate 42 to the rightwill occur until the last of such burners is turned offwhen the rotation ofthecontrol knob will allowthe movement as described above.

The mechanical sensing may also be used in a gas cooker as will now be explained with reference to Figure11.

In the case of a gas cooker, the gas rail usually extends horizontally across the front of the cooker and has mounted upon it notonlygas taps controlling the top burners ofthe cooker butalso a tap controlling an oven burner and a tap controlling a grill burner ifthe cooker includes a grill chamber or if a grill burner is accommodated in the oven.

A horizontal gas rail 52 carries taps 53 controlling gas flow to the top burners, a tap 54that controls gas flowtotheoven burner (not shown) and which incorporates a thermostatic control shown as block 55, and a tap 56 that controls gasflowto a grill burner (not shown). Each tap has an operating spindle 57 each fitted with a control knob and a pinion forming part ofthe control knob. Only one such control knob and pinion is shown in Figure 11 and referenced 58 and 59 respectively.

Mounted in some suitable manner adjacentthe front ofthe gas rail is a spring plate 60 that is movable longitudinally as will be described in more detail below.

The form ofthe plate 60 is similar two that of plate 42 described above with reference to the embodiment shown in Figure 8. Thus plate 60 has apertures 61 through which extend the tap spindles 57. Those apertures associated with the spindles of taps 53 carry racks 62 and bearing strips 63 between which locate the pinions 59 only one of each of which is shown in Figure 11. The apertures of taps 54 and 56 are not fitted with racks and bearing strips.

To the left-hand (as viewed in Figure 11) end of spring plate 60 is connected to restoring spring 64 whilsttheotherend is slotted as at65to engagethe end of one arm 66 of a lever 67 pivotally mounted to rotate about a vertical axis 68. The other arm ofthe lever 67 is upturned as at69 and is slotted at 70.

Located in the slot 70 is a rod 71 with a peripheral groove 72 into which fit the edges of the slot 70. The rod 71 extends rearwardly to the back of the cooker and its remote end acts as a Iockforthe lid (not shown) orto prevent movement ofthe lid ofthe cooker.

The operation ofthe embodiment shown in Figure 11 is generally similarto that ofthe embodiment described above with reference to Figure 8.

Thus, assuming that the cooker lid is closed and all top gas burners off, a userwishingto use atop burner lifts the lid to its fully opened position and then turns on the burner required by rotating the appropriate control knob. Such rotation moves the spring plate to the right as indicated by arrow 73 againstthe action of spring 64. Such movement rotates lever 67 in an anti-clockwise direction with the result that rod 71 is moved into its lid locking position and the lid is locked in its fully opened position. Alternatively, the rod 55 may move into a position in which it merely prevents movement ofthe lid from the fully open position.

As with the embodiment of Figure 8, the movementto the right of the spring plate 60 does not affect any other tap.

To close the lid, the user mustfirstturn offthetop burner in use by rotating the appropriate control knob. That rotation allows spring plate 60 to move to the left thereby, via the clockwise movement of lever 67, withdrawing the rod 71 from its lid locking position.

If morethan one top burner is in use, the movement of the spring plate just described will take place as the last of such top burners is turned off.

It will be appreciated that, in the case of a gas cooker, it is preferable that when the cooker lid is closed, movementofthe spring plate is prevented thereby ensuring that a user cannot turn on any ofthe topburnerswhilstthe lid is closed. The movement may be prevented, for example, by providing a locking rod that is depressed by the lid, when in its closed position, into locking engagement with the lever 67, for example by engaging a suitably placed hole in the lever.

It is possible to modifythe systems just described with reference to Figure 11 to prevent movement of the lid of a cookerfrom its closed position unless all the taps of the top burners are in the "OFF" condition.

Such a modified system will require the addition of a lid operated valve to ensure thatthe supply of gas to the burners is cut-off as the lid is moved from its fully opened to its closed position to ensurethatthe supplyofgasto any burner inadvertently left "ON" as closing movement of the lid is commenced is terminated thereby avoiding possible hazardous conditions.

Alternatively, in a further modification, opening movement of the lid to the position at which the lid-operated valve is opened, is prevented. The iock isso arranged that it will engagethe lid and prevent further movementthereof only as the lid moves from its fully closed position to its fully opened position and preferably operates just before the lid reaches the position at which the lid operated valve is opened.

Again, examples of lid operated valvesandthe method of operating such valves areto beyond in U.K. PatentApplications Nos. 2,109,91 9A and 2,144,845A.

Itwill also be appreciatedthatthe mechanical systems described above with reference to Figures 8 and 11 can also be embodied in electric cookers and in cookers having both top gas burners and electric rings or hot plates or infra-red heaters or some other form of electric heating element.

It will also be appreciated that it is not essential to use a spring plate that is common to all the control units. Alternatively, each such unit may have its own individual rack mechanism individuallyjoinedtothe arm.

Claims (26)

1. Acooking appliance comprising a hob accommodating one or more top heating units and having a lid movable between a fully opened position giving access to the or each top heating unit and a fully closed position in which such access is prevented, and, for the or each top heating unit, a first control device for controlling the supply of energy to the unit, each such first device having an "OFF" condition when the unit is de-energised, and in which means are provided for preventing movement of the lid from a predetermined position unless the or each control device is in the "OFF" condition.

2. Acooking appliance comprising a hob accommodating one or more top heating units and having a lid movable between a fully opened position giving access to the top heating unit or units and a closed position in which such access is prevented, and, for the or each top heating unit a first control devicefor controlling the supply of energytothe unit, each such first device having an "OFF" condition when the unit is de-energised, and in which means are provided for preventing movement ofthe lid from its fully opened position unless the or each control device is in its "OFF" condition.

3. A cooking appliance with one or more top heating units and having a lid movable between a fully opened position giving access to the or each top heating unit and a fully closed position in which such access is prevented, and, for the or each top unit a first control device for controlling the supply of energy to the unit, each such device having an "OFF" condition when the unit is de-energised, and a further control device for controlling the supply of energy to the or each firstflow control device, the further control device being actuable bythe movement of the lid in a mannersuchthatthefurther device is actuatedto preventthe supply of energy when the lid reaches an intermediate position between its fully opened and fully closed positions and to maintain such prevention at all positions of the lid from the intermediate to the fully closed position while at all other positions of the lid such supply is permitted, and in which means are provided for preventing movement of the lid from its fully closed position unless all the or each first control device is in its "OFF" condition.

4. Acooking appliance comprising a hob accommodating one or more top heating units and having a lid movable between a fully opened position giving access to the or each top unit and a fully closed position in which such access is prevented, and, for the or each top unit a first control devicefor controlling the supply of energy to the unit, the or each control device having an "OFF" condition when the unit is de-energised, and, a further control device for controlling the supply of energy to the oreach first control device, the further flow control device being actuable by the lid in a manner such thatthe further device is actuated to prevent the supply of energy when the lid reaches an intermediate position between its fully opened and fully closed positions and to maintain such prevention at all positions of the lid from the intermediate to the fully closed position while in all other positions ofthe lid such supply is permitted, and in which means are provided for preventing movement of the lid from a predetermined position between the fully closed position and the intermediate position to the intermediate position unless the or each control device is in its "OFF" condition.

5. A appliance as claimed in any one of claims 1-4 in which the movement preventing means comprises an arrangement for locking the lid in the predetermined position.

6. An appliance as claimed in any one ofthe preceding claims in which further means are provided for inhibiting the movement preventing means exceptwhen the lid is inthe predetermined position, or in its fully opened or its fully closed position.

7. An appliance as claimed in any one of claims 1-6 in which means may be provided for sensing the condition ofthe or each heating unit to determine whether the respective first control device is in its "OFF" condition, the sensing means being operatively connected to the movement preventing means in such manner as to inhibit operation ofthe latter means only when the device is in its "OFF" condition.

8. An appliance as claimed in any one of claims 1-6inwhich means are providedforsensingthe condition ofthe or each first control deviceto determine whetherthe device is in its "OFF" condition, the sensing means being operatively connected to the movement preventing means in such manner as to inhibit the operation of the latter means only when the device is in its "OFF" condition.

9. An appliance as claimed in claim 6,7 or 8 in which the movement preventing means comprises an electromagnet.

10. An appliance as claimed in claim 9 in which the electromagnet includes an armature to lock the lid in the predetermined position orto prevent movement ofthe lid from that position.

11. An appliance as claimed in claim 9 lOin which means are provided for permitting energisation of the electromagnet when the lid is in the predetermined position and at least one ofthe first control devices is not in its "OFF" condition.

12. An appliance as claimed in claim 11 in which the means permitting energisation comprise a first switch operable to a closed condition when the lid is in its predetermined position and further switches each of which is associated with a different one ofthe first control device and is operable thereby to a closed condition when the first device is not in its "OFF" condition.

13. An appliance as claimed in claim 12 in which thefirstswitch is operable bya cam movablewiththe lid.

14. An appliance as claimed in claim 12 or 13, in which each first control device includes a cam for operating its associated switch.

15. An appliance as claimed in any one of claims 1-8 in which the movement preventing means includes a linkage operable on movementofafirst control device from an "OFF" condition.

16. An appliance as claimed in claim 15 in which the linkage comprises a member common to all the first control devices and is movable thereby when any ofthe first control devices is operated from its "OFF" condition.

17. An appliance as claimed in claim 16 in which each first control device incorporates an arrangementfor moving the memberwhenthe control device is operated from its "OFF" condition unless the slide member has previously been moved by operation by another first control device from its "OFF" condition.

18. An appliance as claimed in claim 17 in which each first control device incorporates a pinion and the slide member includes, for each first control device a rack operable by the pinion ofthe control device to move the slide member when the first control device is operated from its "OFF" condition.

19. An appliance as claimed in claim 18 in which each rack is movable relatively to the slide member within limits defined by the latter.

20. An appliance as claimed in claim 19 in which each rack is mounted in an aperture in the member and in which the extent of the aperture defines the limits of movement ofthe rack.

21. An appliance as claimed in any one of claims 15-20 in which means are provided for locking the linkage against movement when the lid is in its closed position.

22. A hob substantially as herein described with reference to and as illustrated in Figures 1-6 ofthe accompanying drawings.

23. A hob substantially as herein described with reference to Figures 8,9 and 10 of the accompanying drawings.

24. A cooking appliance substantially as herein described with reference to and as illustrated by Figure 7, ofthe accompanying drawings.

25. A cooking appliance substantially as herein described with reference to and as illustrated by Figure 11 of the accompanying drawings.

26. A cooker including a hob as claimed in claim 22 or 23.