GB2106672A

GB2106672A - Household oven

Info

Publication number: GB2106672A
Application number: GB08227665A
Authority: GB
Inventors: Robertus Johannes Mari Gademan
Original assignee: Etna Bv De
Current assignee: Etna Bv De
Priority date: 1981-09-28
Filing date: 1982-09-28
Publication date: 1983-04-13
Also published as: NL8104435A; BE894503A; GB2106672B; DE3233875A1

Abstract

Household oven comprising a heating element for underheating and one for upperheating and a grill controlled by a thermostat with a control for the second element with the conditions of 1) heating it less than the first element; 2) heating it equally as the element; 3) heating it more than the first element; 4) continuously adjusting the heating power to its maximum value. n

Description

SPECIFICATION Household oven This invention relates to a household oven comprising a first heating element for supplying the underheating and a second element which can supply the upperheating and be used as a grilling element, both being cotrolled by a thermostat in response to the oventemperature.

Such an oven is known from the published Dutch patent application 8006470. In this known oven which is provided with a fan for circulating hot air through the oven for obtaining an extra heating of the food to be prepared the second element is exclusively controlled by a thermostat in response to the oventemperature, said thermostat controlling the current supplied to the heating element in an on-off mode. Furthermore the possibility exists to subject the food during the grilling process to hot air, and to the heat radiated by the grill element. For use of the apparatus as a baking oven the second element is connected into series with the first element which supplies the underheat, and in this mode the oventemperature is controlled by the thermostat; there is then a fixed relationship between the heat delivered by the first and the second heating element respectively.

The presence of the fan is a structural complication and increases the price so that this oven is less suited for domestic use; controlling and influencing the baking process is only possible by means of the hot air current.

The invention aims to provide an oven which is not more complicated than the common household oven and is provided with simple, easiiy understood and well laid-out control means which gives the user the possibility to influence the baking process at will.

This aim is obtained according to the invention by a control circuit for controlling the heating power of the second element at will in correspondence with one of the following conditions: a. said heating power being a predetermined value smaller than the heating power of the first heating element; b. said heating power being essentially equal to same of the first heating element; c. said heating power being a predetermined value greater than same of the first heating element; d. said heating power being continuously ad justable to its maximum value.

Varying the power of the second heating element gives the possibility to make either the upper heat or the lower heat predominent at will. Furthermore the use of the second heating element as a grill element gives in a simple way the possibility to subject the food at the end of the baking process to an extra surface heating treatment to form a crust; on the other hand the food to be grilled can also be prepared solely by subjecting it to the heat of the second heating element. In both cases the heating and grill process respectively can be controlled simply and quickly by a proper setting of the setting means of the control circuit; it is not necessary to change the distance of the food to the heating element.

A preferred embodiment is characterised in that the heating elements are electrical heating elements with the current supply thereto, controlled by the thermostat, being controlled by a multiposition switch coupled to the setting means of the thermostat and having at least the following functionai positions: a. current supply exclusively to the first heat ing element; b. current supply to both the first and second heating element; c. current supply exclusively to the second heating element, said current supply being also controlled by the control circuit.

Preferably the control circuit is controlled by means of a single setting element which supplies control signals thereto in correspondence with at least three fixed power values and a number of higher power values which are to be chosen at will.

The invention will be elucidated on the hand of the drawing which shows the circuit of a preferred embodiment of the oven This oven is-provided with a first heating element 1, placed at the bottom of the oven and supplying the under heat and with a second heating element 2 which is placed near the upper wall, which provides the upper heat and can also be used as a grilling element. Furthermore the oven comprises a control circuit 3 for varying the power supplied to the upper element 2; this control circuit can be of any known kind, e.g. with controlled rectifiers or triacs, and has two inputs 4a, 4b respectively, two outputs 5a, 5b respectively and two control inputs 6a, 6b. Such control circuits are commercially available.The inputs 4a, 4b are to be connected to the A.C. mains voltage of e.g. 220 V and control is effected by changing the value of the resistor connected between the terminals 6a, 6b. In the connection between the second heating element 2 and the output 5a, 5b of the control circuit 3 a so-called "maximum-thermostat" 7 switching in response of-a maximum temperature is interconnected and parallel to the inputs 4a, 4b of the control circuit is connected the indicating light 8; the control circuit 3 and the first heating element 1 are connected through a multiposition switch 9 and the oven thermostat 10 to the mains connection 11.

The setting means 1 2 of the thermostat 10 is coupled to the control knob 1 3 of the multiposition switch 9 in a way which is to be described furtheron; the circuit further comprises the oven light, known as such, and the grillspit driving motor 1 5.

Controlling the control circuit 3 is done by means of a threeposition switch 1 6 which is intercoupled with the movable contact of a continuously varying control resistor 1 7. By means of the switch 1 6 three fixed resistors 18, 1 9 and 20 can be connected between the terminals 6a, 6b and in the fourth position of the swtich 1 6 the.resistance between the terminals 6a, 6b is determined by the setting of the control resistor 1 7.

The multiposition switch 9 has three inputterminals indicated with A, B and C respectively and five outputterminals indicated with the numerals 1 to and including 5; the connections which are made between the inputterminals and the outputterminals in the various positions of the switch are indicated in the schematic diagrams I to and including IV at the bottom of the figure.

The circuit operates as follows: In the switch position I there is no interconnection between any of the inputterminals A, B and C and any of the outputterminals 1 to and including 5; as a consequence the oven is completely switched-off.

In position II the inputterminal A is connected with the outputterminal 1 and the inputterminal C with the outputterminal 5; in this position current is supplied to,the oven light.

In the position Ill there is furthermore a connection between the inputterminal B and the outputterminals 2 and 3. As a result the mains voltage is supplied to the first heating element and the inputs 4a, 4b of the control circuit 3 namely through the connection A-1 on the one hand and the connection C-5, the thermostat 12, the connection B-3, B-2 on the other hand. The indicator light will be on.

The power supplied to the second heating element 2 is now determined by the setting of the control circuit 3 and this is in turn dependent upon the position of the switch 1 6 and the control resistor. In the first (left) position of the switch 1 6 the resistor 1 8 is connected between the control inputs 6a, 6b and this resistance has such a value that the power supplied to the element 2 is smaller than the power supplied to the element 1 so that in this position the underheat is predominat. In the second, next, position of the switch 1 6 the resistor 1 9 is connected between the control input 6a, 6b and this resistor has such a value that both heating elements dissipate essentially the same power.In the third position of the switch 16, in which the resistor 20 is connected between the control input 6a, 6b is the power dissipated by the element 2 greater than the power dissipated by the element 1 so that in this position the upper heat is predominant.

The switch 1 6 and the control resistor 1 7 are controlled by a single knob 21 (this is schematically indicated by the dotted line 22) in such a way that a further movement of the control knob 21 to the fourth switching position interconnects the adjustable resistor 1 7 between the inputs 6a, 6b. This makes it possible to vary the power supplied to the heating element continuously to its maximum value: these positions will be used when grilling food.

As stated before the setting means 1 2 of the thermostat 10 is connected to the control knob 1 3 of the multiposition switch 9 in such a way that in position Ill a variation of the temperature at which the thermostat 10 responds is possible over a range of e.g.

60"C-300"C, so that in this position of the switch 9 the oventemperature can be controlled at will. By using the knob 21 the user can in this position make the upper or underheat predominant; furthermore at the end of the baking process food can be quickly provided with a crust.

In the position IV of the switch 9 the element 1 is switched off and only the element 2 is switched on and supplied with current through the control circuit 3; this position will be used for grilling and the grilling heat is determined by the setting of the control resistor 1 7.

Finally in position V an interconnection is made between the input B and the outputs 2 and 4 so that not only the second heating element 2 but also the grilling motor 1 5 is supplied with current: this is the position which will be used when a rotating spit is used.

The oven according to the invention has many different possibilities; the use of the control circuit 3 to supply current to the second heating element 2 results into an important saving of energy.

The multiposition switch 9 connected to the thermostat setting means 12, can be replaced by a number of pushbutton switches or "fingertip" switches, and the combination of the multiposition switch 1 6 and the control resistor 1 7 can be replaced by separate switches; the control elements can be either rotating or sliding elements.

Claims

1. Householdoven comprising a first heating element for supplying the underheating and a second element which can supply the upperheating and be used as a grilling element, both being controlled by a thermostat in response to the oventemperature, characterized by a control circuit for controlling the heating power of the second element at will in correspondence with one of the following conditions: a. said heating power being a predetermined value smaller than the heating power of the first heating element; b. said heating power being essentially equal to same of the first heating element; c. said heating power being a predetermined value greater than same of the first heating element; d. said heating power being continuously ad justable to its maximum value.

2. Householdoven according to claim 1, characterized in that the heating elements are electrical heating elements with the current supply thereto, controlled by the thermostat, being controlled by a multiposition switch coupled to the setting means of the thermostat and having at least the following functional positions: a. current supply exclusively to the first heat ing element; b. current supply to both the first and the second heating element; c. current supply exclusively to the second heating element, said current supply being also controlled by the control circuit.

3. Householdoven according to claim 2, characterized in that the control circuit is controlled by means of a single setting element which supplies control signals thereto in correspondence with at least three fixed power values and a number of higher power values which are to be chosen at will.