GB2184536A - Gas hobs - Google Patents

Abstract

A gas hob provided with a hinged lid incorporates a device which is operated automatically to give an audible and for visible warning signal in the event that the lid is lowered when one or more of the taps controlling the supply of gas to the hob burners is open.

Description

SPECIFICATION Gas hotplates This invention relates to gas hotplates of the kind provided with a hinged lid which normally covers the hotplate when the hotplate burners are not in use, but can be pivoted upwards into a raised position when the hotplate is required to be used.

Although such a hotplate generally includes, asa safety feature automatic cut-out means for cutting offthe gas supply to anyburnerwhich isin use when the lid is lowered, in order to prevent possible damage to the lid, which is commonly made of glass, there is a risk that, as the tap controlling the supply of gas to the burner remains open, the subsequent rais ingofthelid could give riseto an escape ofgasfrom the burner which might not be immediately noticed.

According, therefore, to the invention a hotplate of the kind referred to incorporates a device which is operated automatically to give a warning signal in the event that the lid is lowered when one or more of the taps controlling the supply of gas to hotplate burners is open.

The warning device may be arranged to give an audible and/or a visible warning signal. Preferably the hotplatewill also incorporate, in the usual way, cut-out means for automatically cutting offthe supply ofgas to any burner in use when the lid is lowered.

The hotplate may incorporate means for monitor ingwhetherthe lid isopenorclosed,andalsothe position ofthetaps controlling the supplyofgasto the burners, and comparator means responsive to the monitoring means and arranged to generate an actuating signal for operating the warning device in the event that the lid is closed and at least one ofthe taps is open.

However, where the tap controls are associated with lamps on the control fascia which are arranged to be energized when respective taps are opened, the monitoring means, instead of monitoring the position of the taps directly, may monitor the current drawn by the lamps. This can be achieved in any con- venient manner.

The invention will be further explained by The invention will be further explained by describing, by way of example with reference to Figures 1 to 5 ofthe accompanying schematic drawings one form of hotplate incorporating a warning device in accordance with the invention.

In the drawings Figures 1 and2 illustrates in dia- grammatic form a plan view and a side view ofthe hotplate with the lid closed and open respectively, Figure 3 illustrates, also diagrammatically the manner of operation ofthewarning device, and Figures 4and 5 represent enlarged views of a gas tap control and associated switching arrangement suitable for use in the hotplate.

Referring first to Figures 1 and 2 the hotplate comprises a shallow generally flat metal tray 1 provided with four burners 2 with associated pan supports (not shown), the supply of gasto the burners being controlled by four gas taps 3 provided with spindles fitted with control knobs 5. Indicator lamps 10 are disposed adjacent the respective control knobs 5 for indicating the burners that are being used.

The hotplate may form part of a cooker and be disposed above an oven or it may be arranged to be fitted within an opening in a worktop. The hotplate carries a glass lid 6 hinged at the back and arranged to lie flat, so as to cover the burners, when the hotplate is not being used, but capable of being pivoted upwards into a raised position as shown in Figure 2 to provide accessto the burners 2.

Acut-outvalve7 (Figure 1) connected in the main gas supply line 8 feeding the taps 3 is located atthe rear of the hotplate and is operable by a rocker member (not shown) engageably by a projection at the rear ofthe lid 6 when the latter is raised, this resulting in the opening of the valve so that the gas is supplied to the burners when the respective taps 3 are opened. However when the lid 6 is lowered the valve 7 operates to cut offthe gas supplyto all ofthe burners even though one or more of the burnertaps 3 is/are opened,thus preventing damagetothe lid which could occur if the burner or burners remained alight.

Also disposed at the back of the hotplate is an electrical switch 11 which is open when the lid 6 is opened, but is closed when the lid is lowered. Also each tap 3 is associated with a respective switch 12 (Figures 3 to 5) which is operated when the tap is opened. A monitoring circuit 13 monitors electrical signals generated by detectors 14, 15 and indicative ofthe lid and burnertaps positions, and is arranged to supply an actuating signal to a warning buzzer 16 in the event that the lid 6 is lowered when one or more ofthe burner taps 3 is/are set into the open position.

One particular form oftap/switch arrangement for use in the hotplate as above described is illustrated in Figures 4 and 5. Thus each switch 12 is a magnetically operated switch, and the respective gas tap spindle 4 carries a plate 17 offerromagnetic material which is interposed between the switch 12 and a magnet 18 when the tap is opened the diversion of the magnetic field through the plate, causing the switch to be released and the switch contacts to close, thereby resulting in an increase in current and causing an appropriate signal to be fed to the monitoring circuit 13 from the detector 15.

This is compared, in the monitoring circuit 13, with a signal from the detector 14 which indicates the state of the lid 6, and if the latter is lowered the monitoring circuitwill generate an actuating signal which will operate the buzzer 16, as above described.

It will, however be appreciated that in a hotplate in accordance with the invention other methods of monitoring the lid and/ortap positions may be used if desired.

Thus in place of the comparator circuit a current sensing relay may be disposed in series with all the indicating lamps, so as to be operated and cause the closure of a switch when current drawn by one or more of said lamps indicates that the respective burneror burners is/are alright, the switch being connected in series with the lid switch 11 and the buzzer 16. Alternatively each burnertap mayincor- porate a mechanically operated switch arranged to close when thetap is opened, the switches being connected in parallel with each other and in series with the lid switch 11 and the buzzer 16.

In place of, or in addition to the buzzer 16 a warning light, such as a high intensity neon, may be arranged to be illuminated in the eventthat an attempt be madeto close the lid 6 if a burner is alight. Alternati vely a voice module giving a verbal warning may take the place of the buzzer.

Claims (6)

1. A hotplate of the kind referred to incorporating a device which is operated automatically to give a warning signal in the eventthatthe lid is lowered when one or more of thetaps controlling thesupply of gastro hotplate burners is open.

2. A hotplate according to Claim 1 wherein the said device is arranged to give an audible and/orvisiblewarning signal.

3. A hotplate according to Claim 1 or 2 also incorporating a cut-out means for automatically cutting off the supply of gas to any burner in use when the lid is lowered.

4. A hotplate according to any preceding claim incorporating means for monitoring whetherthe lid is open or closed, and also the position ofthetaps controlling the supply of gas to the burners, and comparator means responsive to the monitoring means and arranged to generate an actuating signal for operating the warning device in the event that the lid is closed and at least one ofthetaps is open.

5. A hotplate according to any of Claims 1 to 3 wherein the tap controls are associated with lamps on the control fascia which are arranged to been- ergized when respective taps are opened, the hotplate incorporating means for monitoring whether the lid is open or closed, means for monitoring the current drawn by the lamps, and comparator means responsive to the monitoring means and arranged to generatean actuatingsignalforoperatingthewarn- ing device in the event that the lid is closed and at least one of the taps is open.

6. A hotplate substantially as herein described with reference to Figures 1 to 4 of the accompanying drawing.