GB2181533A - Cookers and hobs - Google Patents

Abstract

A hob (1) which may be part of a cooker has slid (8) movable between a fully opened position giving access to one or more top burners (2) or other form of top heating unit and a closed position preventing such access. A warning device is fitted which emits a warning which may be audible or visual in the event that the lid is moved from a predetermined position, for example from the fully opened position, and one or more of the burners or heating units is energised. <IMAGE>

Description

SPECIFICATION Improvements in or relating to cookers and hobs This invention relates to cookers and hobs which may be gas or electric. The hob may be an independentunitformounting in a work surface or it maybe 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 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 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 is of glass, may well shatter the glass. 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 gas and damagetothe lid.

Safety measures have been proposed which en sures 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 not entirely satisfactory.

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

According to the present invention, there is provided a hob having one or more heating units and a lid movable between a fully opened position giving access to the unit or units and a fully closed position preventing such access, and also having a warning device for emitting a warning in the event that the lid is moved from a predetermined position and the unit or at least one ofthe units is energised.

The invention also provides a hob having one or more heating units, a lid movable between a fully opened position giving access to the or each unit and a fully closed position preventing such access, and, for the or each unit, a control device controlling the supply of energy to the unit, the device having an "OFF" condition in which the supply ofenergyto the unit is prevented, the hob also having a warning device for emitting a warning in the event that the lid is moved from its fully opened position and the unit or at least one of the units is energised.

According to another aspect, the invention also provides a hob having one or more heating units, a lid movable between a fully opened position giving access to the or each unit and a fully closed position in which such access is prevented, and for the or each unit, a first control device for controlling the supply of energy to the unit, the device having an "OFF" condition in which the supply of energy to the unit is prevented, a further control device for controlling the supply of energy to the or each first control device, thefurthercontrol device being actuable by the lid in a manner such that the further device is actuated to prevent the supply of energy when the lid is in an intermediate position between its fully opened and closed positions and to maintain such prevention at all positions of the lid between the intermediate and the fully closed positions while at all other positions ofthe lid the supply is permitted, the hob also having a warning device for emitting a warning in the event that the lid is moved from its fully closed condition and the control device or at least one of the control devices is not in its "OFF" condition.

Furthermore, the invention also provides a hob having one or more heating units, a lid movable between afullyopened position giving access to the or each unit and a fully closed position preventing such access, and, forthe or each unit, a first control device for controlling the supply of energy to the unit, the first device having an "OFF" condition in which the supply of energy to the unit is prevented, a further control device for controlling the supply of energy to the or each first device, the further control device being actuable bythe lid in a manner such thatthe further device is actuated to prevent the supply of en ergywhenthe lid is in an intermediate position between its fully opened and fully closed positions and to maintain such prevention at all positions of the lid between the intermediate and fully closed positions while at all other positions ofthe lid the supply is permitted, the hob also having a warning device for emitting a warning in the eventthatthe lid is moved from itsfullyclosed condition towards its inter- mediate position with the or at least one of the first control devices not in its "OFF" condition.

Means may be provided for indicating movement ofthe lid and further means for indicating when a heating unitis energised orwhen the or afirstcontrol device is not in its "OFF" condition.

The further means may include a thermally responsive device positioned to respond to heat emitted by the unit when energised.

Alternatively, the further means may comprise a sensor responsive to the condition of the control device.

The sensor may indicate to the warning device when the control device is in an "OFF" condition.

The further means may include an electric switch operable to a closed condition when the or a heating unit is energised and to an open condition when the heating unit is not energised.

The means may include an electric switch and an arrangement for controlling the operation of the switch in dependence upon the position ofthe lid.

The arrangement may comprise a cam movable with the lid.

Alternatively, the arrangement may comprise a member movable on actuation of a control device from an "OFF" condition.

The member may be common to the control devices associated with the hob heating units.

The plate may be operatively linked to each control device bya rackand pinion.

The plate may carry several racks and each control device may include a pinion rotatablewhenthecon- trol device is actuated from an "OFF" condition, each pinion being inoperative engagement with a dif ferent one ofthe racks.

By way of example only, embodiments of the invention will now be described in greater detail with reference to the accompanying drawings of which : Figure 1 is a diagrammatic perspective view of a hob embodying the invention, Figure2is a circuit diagram of a first embodiment, Figures 3and 4 are schematic views of details of the first em bodiment, Figure is a perspective view of part of a second embodiment, Figures Sand 7are explanatory diagrams, and, Figure Bis a perspective view of a third embodiment.

The hob shown in perspective view in Figure 1 comprises a hollow structure 1 which ac commodates four heating units 2 which may be gas burners, electric rings or hot plates, infra-red heating units or some otherform of heating unit, ora combination of such units. The heating units are located above a spillage tray 3 on which rests a pan support structure 4. Where the hob has a ceramic top, the heating units will usually be belowthetop.

Each heating unit has a control device operated by a knob 5 located above a control panel 6forcontrolling 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 gaseous fuel supply passageway leading to the burner.

In the case of electric heating units, the knob 5actuates an electric switch that controls the supply of energy in the form of electricity from electricity supplyterminalstothe unit.

Where gas burners are incorporated, 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 ofthe structure lisa lid 8. In Figure lithe lid is shown in its fully opened position giving access to the heating units and the control panel. The lid is movable by a userfromthe position shown to afullyclosed position in which it conceals and covers the heating units.

Also located in the structure is a counter-balance mechanism operatively conn,ected to the lid for counterbalancing, in a desired manner, the closing weight of the lid. Examples of such mechanisms are found in U.K. PatentApplications Nos. 2,109,91 9A and 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.

The invention provides a safety system which provides a warning indication to a user who attempts to move the lid from a predetermined position forexample the fully opened or fully closed positions without first ensuring that ail the hob heating units are out of use, i.e. the control devices are in an "OFF" condition in which the supply of energy to the unit is prevented.

The warning may be visual or audible or both and will be activated in response to lid movement from the predetermined position and in response to the condition of the control devices.

The system may be electrical having a first switch operable in movement of the lid from the predetermined position and one or more second switches responsive to the condition of the heating units, i.e.

in or out of use.

Thus, in Figure 2, which is a circuit of a first embodiment of the invention, activation of a warning device indicated by block 10 is controlled by the state of switch SI and of parallel connected switches S2-S5.

Switch SI is a lid operated switch and is open when the lid is in its predetermined position but is closed as soon as the lid is moved by a userfrom that position.

Switches S2-S5 are each associated with one ofthe control devices of a hob heating unit. Each switch is open when the associated control device is in its "OFF" condition and is closed as soon as the control device is operated to another condition, i.e. an "ON" condition.

Thus,forexample assuming initiallythatthe lid is in its fully closed position and all the hob control devices are in the "OFF" condition, a user who wishes to usea hob heating unitfirst lifts the lid to gain access two a required heating unitwhich isthen brought into use. In the fully opened position ofthe lid, switch SI is opened. As the heating unit is brought into use that one ofthe switches S2-S5 associated with the control device of the heating unit closes.

If now the user moves the lid from its fully opened position without first returning the control device to its "OFF" condition, the warning device will beenergised because switch SI is closed as soon as the lid is moved and awarning given.Thewarningwillcon- tinue until the user returns the control device to its "OFF" position or returns the lid to its fully opened position.

Alternatively, switch SI is in its open condition ex ceptwhen the lid is in its fully closed position when the switch is closed. In this case, the warning device will be energised as soon as a user moves the lid into its fully closed condition unless all ofthe hob control devices are in the "OFF" condition. If the warning device is energised, the userwili knowthat at least one of the hob control devices is in an "ON" condition and will then take the necessary action by first opening the lid and then to gain access to the devices to return the or each device to its "OFF" position to deenergise the warning. Thus, the next time the lid is opened, all hob heating units will remain deenergised.

It is also possible to arrange that the warning is energised in the event that a user opens the lid after having inadvertently left one or more ofthe control devices in an "ON" condition. As soon as the lid moves away from its fully closed position, switch SI is momentarily closed to energise the warning device which remains energised on further movement ofthe lid even though switch SI is then opened. This requires a slight modification ofthe control circuit and this may be achieved by the use of a latching relay or the equivalent.

In this case, on detecting thewarning,the user continues the opening movement of the lid to gain access to the devices and returns to its "OFF" condition any device not in that condition.

In the alternative embodimentjust described, it is essential to incorporate a lid-operated safety device which prevents the supply ofenergyto all ofthe hob control devices unless the lid is in its fully opened position or nearly so. Should a user inadvertently close the lid with one or more of the hob heating units still in use, the safety device terminates the supply of energyto all the hob units including that one or those in use thereby avoiding damage to the lid and/or other hazards. Lid-operated safety valves are described in U.K. Patent Applications Nos.

2,109,919Aand 2,144,8445A.

In a further alternative embodiment incorporating a lid operated safety device, the system may be so arranged that opening movement of the lid into the position of the lid at which the safety device allows flow of energy to the control devices results in energisation ofthewarning device unless all ofthe heating units are out of use and their control devices in the "OFF" condition. Closing movement ofthe lid will not energise thewarning device.

The switch SI may be operated by a cam or lever movable with the lid. Figure 3 shows a cam 11 that rotates about the pivotal axis 12 oftheklid 8 as the latter moves. Cam 11 is profiled in a manner such that, when the lid is in its predetermined position, switch SI represented in Figure 3 as block 13 is open, the switch operating lever 14 being allowed to move upwardly by the cut away 15 ofthe cam 11 underthe action of a restoring spring in the switch. Once the lid is moved from its predetermined position, the switch SI is closed by the action of the other raised portion 16 of the cam profile.

Figure 4 shows, in diagrammaticformonly,acon- trol unit 17 with an operating spindle 18 carrying a cam 19 that actuates the respective one ofthe switches S2-S5, the switch being shown in Figure 4 as block 20. The switch contains a restoring spring which ensures that the switch returns to its open condition when the control unit is actuated to its "OFF" position to de-energisethe heating unit.

It will be appreciated thatthe state of a hob heating unit, i.e. in use or not, may be sensed in otherways than sensing the state (i.e. "ON" or "OFF") ofthe associated control device. For example, each hob heating unit may include a thermally responsive sensor exposed to heat emitted by the unit. The sensor, which may, for example be a bimetal, isthen used to operate a switch in the group S2-S5.

In the case of a gas burner, the thermally responsive element will sense the presence of a flame atthe burner and will respond rapidly when the flame is ignited or extinguished.

In the case of electric heating units having a con siderable thermal capacity, particularly of the hot plate type, there will be a delay before the unit reaches a temperature at which the sensor will operate the switch. This delay will ensure that the lid can be closed only when the unit reaches a temperature atwhich it will not damage the lid.

Furthermore, it is not essential that each control device has its own switch. The control devices may be operatively linked together to actuate a single switch.

Figure 5 is a perspective of part of a hob employing linked control devices.

Figure 5 shows part ofthe hob 1 with the spillage tray and other components removed. The hob is a gas hob and the structure of the latter associates a gas rail 21 secured in some suitableway in thestructure, for example and as shown in Figure 5 to the side wall ofthestructure.

Mounted upon the gas rail are gastaps 22thatcon trolthesupplyofgasfrom a gas supply passage inside the rail to injectors 23 which, in turn, feed into the gaseous fuel supply passages, referred to above, ofthe gas burners. The gas rail 21 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 24 on which a control knob is located. One such knob is shown at 25.

Each tap includes a niting arrangement which holds the tap locked in its "OFF" position until the spindle is depressed inwardly after which the spindle can be rotated to a required "ON" position. Examples of such valves are found in U.K. Patent Application No.2,129,097A.

Mounted upon the gas rail 21 and secured thereto so asto extend overtheupperends ofthegastaps22 is an elongate plate 26 apertured at spaced positions 27 along its length to permit passage of the spindles 24.

Resting upon the upper surface of the plate 26 and movable along that surface is a spring plate 28 having rectangular apertures 29 thorough which extend the control spindles 24 ofthetaps 22.

On one of the longer edges of each aperture is positioned a rack member 30 whose base is slotted as at 31 to fit over that edge and allow the rack memberto slide along the edge. The length of the rack 30 is less than that of the edge on which it is mounted. The racks 30 each co-operate with a pinion 33 forming part of a respective control knob 25 on each ofthe spindles 24. Only one such knob is shown in Figure 6.

The opposite edge of each aperture 29 supports a bearing strip 32 which holds pinion 33 of the control knob 25 in mesh with the rack. With the taps in the "OFF" positions, the racks 30 abutthe ieft-hand edges of the apertures 29.

Spring plate 28 is biassed to the right as viewed in Figure 6 by a spring 35.

That end of spring plate 28 remote from spring 35 is apertured as shown at 36 and one end of a switch actuating member 37 is located in the aperture. The member operates a switch located inside a housing 38 in a rear corner of the structure 1.

The switch replaces the switch S2-S5 described above with reference to Figure 2 and is closed when any of the taps is not in its "OFF" position. The switch is series connected with a lid operated switch, for example oftheform described above with reference to Figure 3, and with a warning device.

Assuming that the lid 8 is closed, a userwishing to use a hob burner first lifts the lid to gain access to the knobs 25. The knob appropriate to the required burner is rotated to an "ON" position and gas issuing from the burner is ignited.

The positions ofthe spring plate 28 and the racks 30 are then as shown in Figure6 assuming that itis the left-hand (as seen in Figure 6) 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 29.

Movementto the left (as seen in Figure 5) ofthe spring plate 28 occurs against the action of the spring 35. That movement of the spring plate 28 moves the switch actuating member37 and this actuates switch Slto its closed position.

The movementtothe left of the spring plate 28 does not result in rotation of any other control knob because such knobs are held against rotation bythe niting arrangement included in the taps. The result is thatthe spring plate moves relativelyto 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 6.

Movement ofthe lid from its fully opened position will result in energisation of the warning device 10 unless the user has first turned off the gas burner in use by rotating to its "OFF" position the associated control knob. That rotation allows spring plate 28to move to the right under spring 35 thus moving the switch operating lever in the reverse direction and returning the switch Sl to its open position. This position ofthe spring plate is shown in Figure 7 and itwill be observed thatthe rack of the right-hand knob has slid along the aperture and is now in engagement with the left-hand end ofthe associated aperture.

If more than one gas burner is in use, no move ment ofthe spring plate 28to the right will occur until the last of such burners is turned offwhen the rotation ofthe control knob will allowthe movementas described above.

A single switch arrangement may also be used in a gas cooker as will now be explained with reference to Figure 8.

In the case of a gas cooker,the gas rail usually extends horizontally across the front of the cooker and has mounted upon it not only gas taps controlling the top burners ofthe cooker but also a tap controlling an oven burnerand atap controlling a grill burnerifthe cooker includes a grill chamber or if a grill burner is accommodated in the oven.

A horizontal gas rail 36 carries taps 37 controlling gas flow to the top burners, a tap 38 that controls gas flowto the oven burner (not shown) and which incorporates a thermostatic control shown as block 39, and a tap 40 that controls gas flow to a grill burner (not shown). Each tap has an operating spindle 41 each fitted with a control knob and a pinion forming part of the control knob. Only one such control knob and pinion is shown in Figure 9 and referenced 42 and 43 respectively.

Mounted in some suitable manner adjacentthe front of the gas rail is a spring plate 44 that is movable longitudinally as will be described in more detail below.

The form ofthe plate 44 is similar to that of plate 28 described above with reference to the embodiment shown in figure 5. Thus plate 44 has apertures 45 through which extend the tap spindles 41. Those apertures associated with the spindles of taps 31 carry racks 46 and bearing strips 47 between which locate the pinions 43 only one of each of which is shown in Figure 8. Theapertures oftaps 38 and 40 are not fitted with racks and bearing strips.

To the left-hand (as viewed in Figure 8) end of spring plate 44 is connected a restoring spring 48 whilst the other end is slotted as at 49 to engage the end of one arm 50 of a switch actuating lever 51 pivotally mounted to rotate about a vertical axis 52. The other arm of the lever is upturned as at 53 to form an actuating surface for the operating button 54 of a switch represented as block 55 and which replaces the group of switches S2-S5 described above with referenceto Figure 2.

The operation ofthe embodiment shown in Figure 8 is generally similar two that of the embodiment described above with reference to Figure 5.

Thus, assuming that the cooker lid is closed and all top gas burners off, i.e. switch SI closed and switch S5 open, a user wishing to use a top burner lifts the lid to its fully opened position thereby opening switch SI and then turns on the burner required by rotating the appropriate control knob thereby closing switch S5. Such rotation moves the spring plate to the right as indicated by arrow 56 against the action of spring 48. Such movement rotates lever 51 in an anti-clockwise direction with the result that surface 53 is moved against button 54 and switch 55 is closed.

As with the embodiment of Figure 5, the movementto the right ofthe spring plate 44 does not affect any other tap.

Before closing the lid, the user mustfirstturn off the burner in use by rotating the appropriate control knob. That rotation allows spring plate 44to move to the leftthereby, via the clockwise movement of lever 51, withdrawing the surface 53 from its previous position and allowing switch S5 to open under the action of its internal restoring spring. The warning device is thus not energised because although switch SI will be closed as soon as the lid moves from its fully opened position, switch S5 is now open.

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

If, however, the user inadvertently omits to turn off the burner in use before closing the lid, switch S5 re mainsclosedandassoon asthelid8ismovedfrom its fully opened position, switch SI is closed and the warning is energised to remind the user to turn off the burner. That action opens switch S5andter minates the warning.

It will be appreciated that, in the case of a gas cooker, it is preferable that when the cooker lid is closed, movement of the spring plate is prevented thereby ensuring that a user cannotturn on any ofthe top burners whilst the lid is closed. The movement may be prevented, for example, by providing a locking rod that is depressed bythe lid, when in its closed position, into locking engagement with the lever 51, for example by engaging a suitably placed hole in the lever.

It is possible to modify the systems just described with reference to Figures 5-8 to provide energisation of the warning device when the lid reaches its closed position unless all the taps ofthe hob burners are in the "OFF" position. Such a modified system will require the addition of a lid operatedvalveto ensure that the supply of gas to the burners is cut-off as the lid is moved from its fully opened to its closed position to ensure that the supply of gas to any burner inadvertently left "ON" as closing movement ofthe lid is commenced is terminated thereby avoiding possible hazardous conditions.

Alternatively, in a further modification, opening movement ofthe lid to the position atwhichthe lid operated valve is opened, will energise the warning device unless all taps are in the "OFF" position. The lid cam is so arranged that it will close switch SI only as the lid moves from its fully closed position to its fully opened position and preferably closes the switch just before the lid reaches the position at which the lid operated valve is opened.

Again, examples of lid operated valves and the method of operating such valves areto be found in U.K. PatentApplications Nos. 2,109,919A and 2,1 44,845A.

It will also be appreciated that the mechanical systems described above with reference to Figures 5 and 8 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 individually arranged to actuate a switch corresponding with switch S5.

Claims (19)

1. A hob having one or more heating units and a lid movable between a fully opened position giving access to the unit or units and a fully closed position preventing such access, and also having a warning device for emitting a warning in the event that the lid is moved from a predetermined position and thatthe unit or at least one of the units is energised.

2. A hob having one or more heating units, a lid movable between a fully opened position giving accessto the or each unit and a fully closed position preventing such access, and, for the or each unit, a control device controlling the supply of energy to the unit, the device having an "OFF" condition in which the supply of energy to the unit is prevented, the hob also having awarning device for emitting awarning in the event that the lid is moved from its fully opened position and the unit or at least one of the units is energised.

3. A hob having one or more heating units, a lid movable between a fully opened position giving access to the or each unit and a fully closed position in which such access is prevented, and for the or each unit, a first control device for controlling the supply of energy to the unit, the device having an "OFF" condition in which the supply of energy to the unit is prevented, a further control device for controlling the supply of energy to the or each first control device, thefurthercontrol device being actuable bythe lid in a manner such that the further device is actuated to preventthe supply of energy when the lid is in an intermediate position between its fully opened and closed positions and to maintain such prevention at all positions ofthe lid between the intermediate and the fully closed positions while at all other positions of the lid the supply is permitted,the hob also having a warning device for emitting a warning in the event that the lid is moved from its fully closed condition and the control device or at least one ofthe control devices is not in its "OFF" condition.

4. A hob having one or more heating units, a lid movable between afullyopened position giving access to the or each unit and a fully closed position preventing such access, and, for the or each unit, a first control device for controlling the supply of en ergyto the unit, the first device having an "OFF" condition in which the supply of energy to the unit is prevented, a further control deviceforcontrolling the supply of energy to the or each first device, the further control device being actuable by the lid in a manner such that the further device is actuated to prevent the supply of energy when the lid is in an intermediate position between its fully opened and fully closed positions and to maintain such preven- tion at all positions ofthe lid between the intermediate and fully closed positions while at all other positions of the lid the supply is permitted, the hob also having a warning device for emitting a warning in the event that the lid is moved from its fully closed condition towards its intermediate position with the or at least one ofthe first control devices not in its "OFF" condition.

5. A hob as claimed in any one of the preceding claims in which means are provided for indicating movement ofthe lid and further means for indicating when a heating unit is energised or when the or a first control device is not in its "OFF" condition.

6. A hob as claimed in claim 5 in whichthefurther means includes a thermally responsive device positionedto respond to heat emitted by the unitwhen energised.

7. A hob as claimed in claim 5 in which thefurther means comprises a sensor responsive to the condition ofthe control device.

8. A hob as claimed in claim 7 in which the sensor indicates to the warning device when the control device is in an "OFF" condition.

9. A hob as claimed in anyone of claims 5-8 in which the further means includes an electric switch operable to a closed condition when the or a heating unit is energised and to an open condition when the heating unit is not energised.

10. A hobasclaimed in anyone ofclaims 5-9 in which the means includes an electric switch and an arrangementforcontrolling the operation ofthe switch in dependence upon the position of the lid.

11. A hob as claimed in claim 10 in which the arrangementcomprises a cam movablewith the lid.

12. A hob as claimed in claim 10 in which the arrangement comprises a member movable on actuation of a control device from an "OFF" condition.

13. A hob as claimed in claim 12 in which the member is common to the control devicesassociated with the hob heating units.

14. A hob as claimed in claim 13 in which the member comprises a plate operatively linked to each control device buy a rack and pinion.

15. A hob as claimed in claim 14 in which the plate carries several racks and in which each control device includes a pinion rotatable when the control device is actuated from an "OFF" condition, each pinion being inoperative engagement with a dif ferentone of the racks.

16. A hob substantially as herein described with reference to and as illustrated by Figures 1,2,3 and 4 ofthe accompanying drawings.

17. A hob substantially as herein described with reference to and as illustrated by Figures 5,6 and 7 of the accompanying drawings.

18. A cooker including a hob as claimed in any one of claims 1-17.

19. Acooker substantially as herein described with reference to and as illustrated by Figure 8 ofthe accompanying drawings.