GB2081889A

GB2081889A - Cooker grill

Info

Publication number: GB2081889A
Application number: GB8118047A
Authority: GB
Original assignee: Kenwood Manufacturing Co Ltd
Current assignee: Electrical and Musical Industries Ltd
Priority date: 1980-07-25
Filing date: 1981-06-12
Publication date: 1982-02-24
Also published as: GB2081889B

Abstract

In order to eliminate unnecessary wastage of energy and to increase the flexibility of use of a cooking grill, the grill is provided with separate, independently energisable heating elements for heating the central region of the grill and the end regions. The end regions are heated by respective elongate U- shaped portions A1, A2 of a first heating element A, while the central region of the grill is heated by two heating elements B and C, arranged in a serpentine configuration. Three modes of operation are provided, namely B only, B plus C, and A plus B. A similar arrangement of gas burners may instead be provided. <IMAGE>

Description

SPECIFICATION Cooker grill The present invention relates to cooker grills and more particularly to an arrangement of heaters for a cooker grill.

In an electric grill, there are usually two heating elements, one for the right hand half and one for the left hand half of the grill. However it has been found that the user frequently only uses the middle half of the width of the grill and then the heating elements wastefully deliver power to parts of the grill where it is not required.

According to the present invention, there is provided a cooking grill having a heater arrangement comprising independently operable means for heating the longitudinal central region of the grill and the end regions of the grill.

Preferably the grill is an electric grill and the heaters are electric heating elements. The means for heating the end regions of the grill may be two portions of a single heater, these portions being disposed to opposite sides of a separate heater arrangement to heat the central region.

The invention will be further described by way of example with reference to the accompanying drawings in which: Figure 1 is a diagrammatic plan view showing the arrangement of heating elements in one embodiment of the present invention; and Figure 2 shows the heating elements of Figure 1 connected to a controller.

Figure 1 shows the heating elements of a domestic electric cooker grill embodying the present invention.

It will be seen that the grill is provided with three separate heating elements, A, B and C, the heating element A being arranged to deliver heat principally to the left and right hand end regions, Land R respectively, of the grill while heaters B and Care arranged to deliver heat to the longitudinal central region M of the grill. The widths of the regions Land Rare each a quarter of the width of the grill.

It will be seen that the elements B and Care shaped so as to conform to one and a half cycles of a serpentine configuration and resemble a rounded letter "W". The element A comprises two portions Al and A2 disposed to opposite sides of the elements B and C and each in the shape of an elongate letter "U" and interconnected by a run A3 of the heating element conductor extending laterally of the grill at its rear.

The heating elements A, B and C are all of equal rating and, by means of a controller such as the controller 1 shown in Figure 2, are independently energisable in three modes, 1,2 and 3. These modes are as follows: 1. Only element B is energised. This mode is used when the item is to be grilled can be accomodated on the central region M of the grill and can be adequately grilled energising only the heating element B.

2. Heating elements B and C are energised concurrently. This provides double the power density in region M as compared with mode 1 and can therefore be used for intense grilling, for example where rapid toasting is required.

3. Elements A and B are energised concurrently.

This gives even heating over the width of the grill.

Figure 2 shows in block diagram form the control circuits associated with the embodiment of Figure 1.

A controller 1 is arranged to control the energisation of the heating elements A, B and C by means of respective triacs 2, 3 and 4 connected in series with the heating elements across the electrical mains supply, this energisation being carried out in dependence upon the settings of two user-operable controls 5 and 6. Control 5 is a heat setting control which may, for example, be a user-operable potentiometer, for selecting the desired level of heating, while control 6 is used to select the desired one of the above three modes of operation and may, for example, be a multi-position switch.

The controller 1 may be a burst fire controller of known type, that is to say a controller which is arranged to gate the triacs 2-4 so that each conducts for an integral number of half cycles of the electrical mains supply per unit time, this number being determined in dependence upon the setting of the control 5 (and also in dependence upon the detected temperature of the heating elements if closed loop control of the heating elements is required).One well known form of burst fire controller compares a signal derived from the user-operated control 5 with the output of a free running ramp generator having a time period of several seconds and is arranged to provide gating pulses suitably timed, by zero crossing detecting circuitry, with the zero crossovers of the alternating mains supply so that the triac conducts for an integral number of half cycles commencing and ending with zero crossovers of the mains supply waveform.

As described in our copending British Patent Application No. 7940618, if it is desired to arrange for extra rapid heating of the heating elements to working temperature, this may be achieved by designing the heating elements so that they produce their rated output at somewhat below the nominal mains voltage, for example 180 V for a 240 V supply.

During normal operation, the controller 1 is arranged so that they are energised in a mark to space ratio such that they produce their nominal rated output but when rapid heating is required, for example during the initial warming up period and/or when there is an increase in the setting of the useroperated control 5, the heating element or elements in question are energised continuously for a short period of, say, 30 seconds to a minute and a half so that they are overrun and produce more power than their nominal rated output. This overruning can be carried out with safety because it only occurs for relatively short periods.

The heating elements A, B and C may be so designed and the controller 1 so arranged so as to provide this rapid warm up facility in one or any combination of the three modes of operation.

While in the illustrated embodiment the energisation of the elements is controlled by a burst fire controller it will be appreciated that conventional bimetallic regulators could be used instead.

It will be appreciated that as well as to electric grills, the invention may be applied to gas grills. In those circumstances independently operated burners are provided to heat the central region on the one hand and the end regions of the grill on the other.

Claims

1. A cooking grill having a heater arrangement comprising independently operable means for heating the longitudinal centre region of the grill and the end regions ofthe grill.

2. A cooking grill according to Claim 1, wherein said means comprises respective independently energisable electric heating elements.

3. A cooking grill according to Claim 2, wherein the ends of the grill are arranged to be heated by respective portions of a common electric heating element.

4. A cooking grill according to Claim 3, wherein said portions are each of elongate U-shape and are linked by a connecting run extending across the longitudinal centre region of the grill.

5. A cooking grill according to Claim 2,3 or 4, wherein the central heater is in a serpentine configuration extending across the width of the longitudinal centre region of the grill.

6. A cooking grill according to any one of Claims 2 to 5 wherein the central heater comprises two independently energisable elements in side by side relation.

7. A cooking grill according to Claim 6 and including a control arrangement defining a number of modes of operation, namely a first mode in which only one of the central heating elements is energised, a second mode in which both the central heating elements are energised and a third mode in which one of the central heating elements and the grill end heating element are energised.

8. A cooking grill according to Claim 1 wherein the independently operable heating means comprises respective gas burners.

9. A cooking grill constructed and arranged substantially as hereinbefore described with reference to and illustrated in the accompanying drawings.

10. A domestic cooker incorporating a cooking grill according to any one of the preceding claims.