GB2226714A - Electric cooker - Google Patents

Abstract

The cooker has the live ends of its element controllers 7, 8, 9, 10, 19, 20 connected to a loop conductor 22 connected to a line input terminal 1 and the low ends of its heating elements 3, 4, 5, 6, 11, 15, 18 connected to a further loop conductor 23 connected to a neutral supply terminal 2. The cooker may have dual ovens with respective heaters 15, 18 and thermostat 16, 19, the main oven thermostat 16 being connected to the line conductor loop 22 via a timer 20. A grill is positioned in the secondary oven and its energy regulator 12 is supplied via the secondary oven thermostat 19 so that the grill and secondary oven heaters 11, 18 are not energised simultaneously. <IMAGE>

Description

ELECTRIC COOKERS The invention relates to electric cookers.

Electric cookers, particularly those intended for domestic use, are normally operated from a single phase supply and have a pair of input terminals1 one of which is connected to a live phase wire at line voltage and the other to the neutral wire at, or very close to, earth potential. The heating elements of the cooker are each provided with control devices, which may be switches, energy regulators or thermostatic devices, and these are connected in series with the heaters at the live ends of the heaters, so that when they are switched off the whole of the heater is at or near earth potential.

Electric cookers have a cable entry normally positioned at the back of the cooker, inside which are a pair of power input terminals for connection to the line and neutral conductors of the supply, and the switches or energy regulators are normally grouped in a control panel at the front or side of the oven or hob. The live terminals of the control devices hitherto have each been connected by a separate conductor to the line supply terminal, and the low ends of the heaters have each been connected by a separate conductor to the neutral supply terminal. The wires are of heavy gauge, since they are required to carry large currents, and are insulated with a high-temperature-resistant insulation.

The present inventor has appreciated that the conventional wiring of cookers as described above is unnecessarily complicated, and is extravagant in its usage of copper and of high grade insulation.

According to the present invention an electric cooker for connection to a single phase supply comprises live and neutral input power terminals and a plurality of heating elements, each with a control device, characterised in that a conductor from the line input terminal is connected consecutively to the line input terminals of each control device and is returned to the line input terminal, and a further conductor from the neutral input terminal is connected consecutively to the low voltage end of each heating element and is returned to the neutral input terminal.

If the cooker includes an oven the control device will generally comprise a thermostat, and a timer will be provided, the timer of course being connected between the line conductor loop and the neutral conductor loop.

It will be appreciated that this method of connection involves only four wires being taken from the control panel to the supply input terminals, two of them to the line terminal and two to the neutral terminal. The method of interconnection, as will be apparent, is analogous to the ring mains system used for domestic wiring.

A cooker circuit according to the invention will now be described by way of example with reference to the accompanying drawing, which is a circuit diagram showing the interconnection of the heaters and their control switches in a typical cooker having hob plates, a main and secondary oven, and a grill.

The cooker has a pair of supply input terminals 1 and 2, of which 1 is to be connected to the phase line of the supply and 2 to the neutral line. The cooker has a hob with four hotplates whose heating elements are designated 3,4,5 and 6, with respective energy regulators 7,8,9 and 10. Hob plate 5 has a dual heating element, the inner section of which can be used independently of the outer under the control of its energy regulator, but this detail is not relevant to the present invention and will not be described further here.

A grill 11 is also controlled by its own energy regulator 12, and this grill again has separate inner and outer sections.

The cooker has two ovens. The main oven has an element 15 controlled by a thermostat 16 and is also provided with a circulating fan 17 for convective distribution of heat. The secondary oven has its element 18 controlled by a further thermostat 19. A timer 20 enables the ovens to be pre-set.

The cooker also includes a door operated oven light, a hob light, an overhead light, and various indicators which need not here be described in detail.

In accordance with the wiring arrangement of the present invention, a conductor 22 is connected from line terminal 1 in turn to the line terminals of the four hob plate energy regulators 7,8,9 and 10, to the secondary oven control thermostat 19, and to the timer 20. It is then returned to the line supply terminal 1, forming a closed loop. The main oven thermostat 16 takes it supply through the timer 20, and the grill energy regulator is supplied through the secondary oven thermostat. This is because the grill is positioned in the secondary oven and the thermostat incorporates a switch to ensure that the oven element and the grill element are not operative simultaneously.

A conductor 23 is connected from the neutral supply terminal in turn to each of the energy regulators 7,8.9 and 10, to the grill energy regulator 12, the timer 20, and then to the low ends of the heating elements 15, 18, 11, 6, 5, 4, and 3 before being returned to the neutral terminal 2.

The conductors 22 and 23 each form a closed loop, which, in the drawing, has been emphasized by heavier lines for clarity, and it will be appreciated that this corresponds to a ring main system of the kind used for household wiring.

Claims (3)

1. An electric cooker for connection to a single phase supply comprising line and neutral input power terminals and a plurality of heating elements each with a control device characterised in that a conductor from the line input terminal is connected consecutively to the line input terminals of each control device and is returned to the line supply input terminal, and a further conductor from the neutral input supply terminal is connected consecutively to the low voltage ends of each of the heating elements and is returned to the neutral input terminal.

2. An electric cooker according to claim 1 further including an oven and a timer for controlling the oven, the timer being connected between the said conductors, and the control device for the oven being a thermostat connected to the line input conductor loop through the timer.

3. An electric cooker having its heating elements and the control devices for the heating elements connected between line and neutral input terminals substantially as shown in and as herein described with reference to the accompanying drawing.