EP1774831A1

EP1774831A1 - Device for switching a number of heating devices of a cooking appliance and cooking appliance equipped with such a device

Info

Publication number: EP1774831A1
Application number: EP05775822A
Authority: EP
Inventors: Eugen Wilde; Erich John; Hans Mohr; Ralf Stoll
Original assignee: EGO Elektro Geratebau GmbH
Current assignee: EGO Elektro Geratebau GmbH
Priority date: 2004-08-03
Filing date: 2005-07-26
Publication date: 2007-04-18
Anticipated expiration: 2025-07-26
Also published as: PL1774831T3; WO2006015719A1; US7180038B2; ES2546791T3; EP1774831B1; US20060027564A1

Abstract

A control device is provided for switching on and off two heating devices (13, 15) of a cooking top (17) that form a multicircuit cooking area (19). The level of stable generation of energy and power can be set by an energy control unit (21) in a clocked manner. A temperature limiter (23) monitors a maximum temperature above the first heating device (13) but not over the second heating device (15). The energy control unit (21) directly activates or switches the first heating device (13). The temperature limiter (23) activates a power relay (32) in order to switch the second heating device (15) simultaneously with the first heating device (13).

Description

description

Device for switching a plurality of heating devices of a cooking appliance and cooking appliance with such a device

The invention relates to a device for switching or switching on and off of several heating devices of a cooking appliance and a cooking appliance with such a device.

For hobs with, for example, glass ceramic plates, there are radiant heaters with a diameter that can be greater than 230 mm. Some of these have the problem that an energy supply by so-called energy control devices on the one hand and an excess temperature protection for the glass ceramic plate over the radiant heating by so-called temperature limiters on the other hand are limited by maximum achievable powers and a so-called flicker standard. The Fli¬ cker standard indicates how often in a certain time a certain power can be switched on or off in a cooking appliance and should prevent major network perturbations in the sense of the energy supply companies. The switching capacity of both the energy control devices and the temperature limiter, which operate with so-called Schnapp¬ switches, as described for example in EP 898 291 A and DE 33 33 645 A, is generally limited. For example, for the US, these are 12 and 13 amps respectively. This is because 100,000 switching cycles must be achievable.

At usually given mains voltage thus a further increase in the power of a radiant heater is not possible.

Task and solution

The invention has for its object to provide a Vor¬ mentioned direction and a cooking appliance mentioned above, with the NEN the problems of the prior art can be avoided and in particular in a hotplate with radiant heating, the maxi¬ male performance can be increased.

This object is achieved by a device having the features of claim 1 and a cooking appliance having the features of claim 8. Advantageous and preferred embodiments of the invention are the subject matter of further claims and are explained in more detail below nä¬ forth. The wording of the claims is made the subject of the description by express reference. For the purposes of this application, "having" means that this feature can be provided, among others, independently of other features.

According to the invention, it is provided that the device has a temperature detection device or, under certain circumstances, forms such a device which has a temperature-dependent thermomechanical triggering movement as a functional principle. The temperature detection device has or is connected to a first switching device, which can be actuated directly by a triggering movement at an adjustable triggering point in order to switch the first heating device on and off. A second switching device is provided for switching on and off the second heating device. This second switching device can also be activated by the tripping movement. Both the first switching device and the second switching device are designed for the switching of the heating power of the respective heating device, ie as a so-called power switch, such as relays. They are also designed so that they reach the required number of Schalt¬ cycles. For the second switching device or its release is provided that it can be activated directly or indirectly by the release movement. In a direct activation, the switching contacts are moved directly by the tripping movement. In an indirect activation in the context of the present application is due to the - O -

Triggering of the first switching device by the release movement and the signal caused thereby or a switched voltage, the second switching device activated. Thus, the activation does not take place directly mechanically via the tripping movement, but indirectly, by being controlled by the first switching device activated by the tripping movement.

The invention thus makes it possible to provide a temperature detection device which, instead of a conventional temperature limiter, as is apparent, for example, from DE 33 33 645 A, can be provided for monitoring the glass-ceramic plate of a hob with radiant heating against excess temperature , The two heaters belong to a single hotplate, so they are operated together at least occasionally. In particular, it is a so-called two-or Mehrkreiskochstelle. The temperature detection device thus triggers the first and the second switching device, wherein each switching device switches its respective assigned heating device on or off. Thus, in the case of an excess temperature, the entire power of the cooking station no longer switched by a single switching device of the temperature detection device wer¬, whereby the overall performance of the heaters or the Koch¬ can be increased point.

When using relays as switching devices, it is preferred if they are designed such that they are open in the de-energized state, ie in the deactivated or non-activated state. Then the connected heating devices are switched off.

In a first possibility of the invention it can be provided that the second switching device can be activated directly by the first switching device. This can be done, for example, such that when the first switching device is closed to turn on the first Heating device, the second switching device receives a corresponding elektri¬ cal signal, in turn, then turn on the second heater to turn on or turn. Alternatively, the second switching device can be supplied with energy from the connection of the first heating device to a supply voltage for activation. Thus, it is provided in this embodiment that the second Schaltein¬ direction is not activated directly by the release movement, but indirectly, by being controlled by the activated by the tripping ers¬ th switching device.

In another possibility of the invention, a third Schaltein¬ direction can be provided, which is connected to the temperature sensing device or coupled and is actuated at an adjustable Aus¬ release point directly by the release movement. An actuation advantageously takes place simultaneously with the first switching device, ie at the same triggering point. Such a third switching device can directly activate or energize the second switching device, so that it switches the second heating device on or off accordingly. Here, therefore, the second switching device is activated by the third switching device instead of the first switching device as in the previous embodiment. This has the advantage that no further functions or connections are to be provided for the first switching device in this case. However, the third switching device is provided. However, it is possible to use a switching device for this purpose, in conventional temperature limiters such as DE is seen anyway vorge 33 33 645 A in the case to indicate a temperature still above example, 100 ⁰ C as so-called hot display.

In principle, in a further possibility of the invention it is also possible to install the second switching device in the same way in the temperature sensing device as the first switching device, in particular special in the same structural design. In this case, even more stringent structural requirements have to be met, in particular also with regard to insulation resistances and distances.

The third switching device for driving the second switching device can either operate at a lower voltage than mains voltage or be designed for significantly lower currents. Your task is only to switch the activation current for the second switching device. In the case of power relays as well as under certain circumstances electronic switches this is relatively low, so that no increased mechanical or kontaktspezifi¬'s requirements are to be placed on the third switching device.

The temperature detection device can advantageously have an expansion device, which expands depending on the detected temperature or causes a mechanical release movement. For example, it may be a temperature limiter, as disclosed in DE 33 33 645 A, to which reference is expressly made in this regard and whose content is made by express reference to the content of this application. Such a temperature limiter can have two elongated and parallel longitudinal elements which are coupled at one end and have different temperature expansion coefficients. At a predetermined or detected temperature, these expand to different degrees, and this relative movement causes the release movement, since at the non-coupled end, the relative movement takes place between them. For this purpose, one of the elements can be fixed to the temperature detection device. The other moves relative thereto and calls forth a force which, together with the release movement, can actuate, for example, a switching device or the like. - D -

In a further embodiment, the device may have or be connected to a drive for the heating devices, for example a so-called clocking energy control device. By such a wer¬ the example, radiant heater operated clocking, which means that they are either switched off or switched on with full power on. Thus, the amount of energy generation at the heating devices can be given over several cycles or for a specific time. This is described in the aforementioned EP 898 291 A, the content of which is made by express reference to the content of this application. It is provided that when the An¬ control is switched off, none of the aforementioned switching devices is activated or activatable. This ensures that, in principle, the amount of power generation or the type of clocking is predetermined by the control or the energy control device. Advantageously, the temperature-sensing device merely provides overheating protection, for example a glass-ceramic plate against excessive heating by the heating devices.

An inventive cooking appliance may include an aforementioned device for at least two independently controllable heating devices. These two heating devices form a cooking point or are arranged very close to one another, so that they are used together in some operating modes for heating a single appropriately sized cooking vessel arranged thereon. Herein, the first heater is a main heater, while the second heater is an auxiliary heater. The second heating device can either connect laterally to the first heating device in approximately one half, if necessary, it can even completely surround it. For smaller cooking vessels is vorgese¬ hen to heat them only with the first heater. In larger cooking vessels, which cover the entire surface of the first and the second heater, both heaters _

used together. In such a common use, it is of course advantageous if the temperature detection device switches off not only these but also both heating devices in the case of an excess temperature at a region, in particular at the region of the first heating device. Otherwise, especially when using radiant heaters, an image unfamiliar to the operator would be displayed.

It is advantageously provided that the power of the first heating device is substantially greater than that of the second heating device, for example about twice as large.

For the second heating device, a maximum continuous power corresponding to a power density of at most about 2.5 W per cm ² can be provided. Such a value has the advantage that, when using radiant heaters and a glass ceramic plate as hob, such a power density can be operated as it were unprotected, ie without temperature monitoring for the glass ceramic. Harmful temperatures of about 550 ⁰ C and more can not be achieved er¬. Such power densities can not lead to overheating of the glass ceramic. The power density can also be selected above 2.5 W / cm ² , if the specifications or tests of the manufacturer of the glass-ceramic result or permit. The power of the second heating device is particularly advantageously used for a holding function for a placed cooking vessel, in particular with a cycle operation. For this purpose, a lower power density is good. This can also be rationalized when the control of the heaters via clocking power relay takes place, for example, controlled by touch switch as controls.

This makes it possible for the temperature detection device, in its function as overheat protection, to use only the first heating device - o -

must monitor, but not the second. For example, it can cover the first heating device, but not the second heating device. Alternatively, it may be activated in the region of the second heating device. For this purpose, it is possible that, for example, in the case of a previously mentioned rod regulator in the region to be deactivated, one of the two longitudinal elements is partially replaced by another partial longitudinal element which has the same temperature expansion as the other longitudinal element. Thus, by heating in the region to be deactivated, no relative movement or no contribution to a relative movement is effected.

The cooking appliance can advantageously have a clocking energy control device, as has been described above and can be seen, for example, from EP 898 291 A. This energy control device is designed at least for the activation of the first heating device. As a result of the fact that the second heating device is activated or activated via the aforementioned device or the temperature detection device, and the total power level of the heating devices is determined by the energy control device, this outputs the switching on and off times both for the first one Heating device as a result and as a result for the second heating device.

In a further embodiment, a fourth switching device can be provided, which independently of the second or third switching device, the second heater ever activated or deactivated for synchronous operation with the heater. This fourth switching device may, for example, allow an operator, depending on the size of the attached cooking vessel, to basically activate the additional heater or not. It can be formed, for example, by a circuit breaker inserted in the supply voltage, in particular a relay, with a corresponding control for an operator, for example a touch switch. Furthermore, - y -

be seen that the second switching device is provided separately from the energy control device on the cooking appliance. This can, as has been described above, be a separate circuit breaker, in particular a relay.

These and other features are apparent from the claims and from the description and the drawings, wherein the individual features in each case alone or more in the form of Unter¬ combinations in one embodiment of the invention and in other areas ren be realized and advantageous as well as for selbstfähfähi¬ ge represent versions for which protection is claimed here. The subdivision of the application into individual sections as well as subheadings does not limit the statements made thereunder in their generality.

Description of the drawings

Embodiments of the invention are shown schematically in the drawings and will be explained in more detail below. In the drawings show:

1 shows a functional diagram of an arrangement with which two heating devices can be controlled via an energy control device and a temperature limiter;

2, the arrangement according to FIG. 1, which forms a cooking point of a hob,

3 shows the arrangement according to FIG. 2 in a lateral view with the cooking point under a glass ceramic plate, FIG.

4 is a plan view of the internal structure of a Temperaturbegren¬ zers, which is designed as a so-called rod controller,

Fig. 5 shows an alternative embodiment of a temperature limiter and

6 shows a further alternative embodiment of the arrangement according to FIG. 1. Detailed description of the embodiments

1 shows a functional diagram of a device 11 according to the invention, with which a first heating device 13 and a second heating device 15 can be activated. These can form a so-called two-circuit heater, as shown in FIG. 2 and explained in more detail there. Both heaters 13 and 15 are so-called radiant heaters, as described for example in EP 590 315 A. They are operated with mains voltage, so for example 240V. Their operation is usually carried out in a clocking manner such that a heating device either rests on the supply voltage and operates at full power or is disconnected from the supply voltage and is thus deactivated. The amount of power generation over a period of time does not occur by lowering the supply voltage for continuous operation, but by clocking on-times and off-times. By the Takt¬ ratio or the length of the respective on and off times, the so-called average energy production can take place or results in the so-called average power. It can also be seen from the drawing that the two heating devices 13 and 15 are galvanically separated from one another, which is generally advantageous.

It can be provided not shown securing means, which can turn off one of the heaters 13 or 15 at excess temperature in the trough of the hob. This has the advantage that not only the glass ceramic 18 is protected against excessively high temperature, but also the structural units such as the electrical system or electronics in the trough. Likewise, the environment of the hob 17 is protected. These safety devices are advantageous for the heaters 13 and 15 separately or respectively provided in their control. It may be, for example, so-called Klixons, in particular as in distributed to the USA. These are bimetallic switches that open a contact when a certain temperature is exceeded, wherein the switching point is set to the critical or too high temperature. In such safety devices can also be provided that only one of the two heaters a fuse is available. By reducing a part of the heat output too high a temperature Tempe¬ can usually be avoided.

For the control of the first heating device 13, namely in the vor¬ said manner with on and off times in a clocking manner, an energy control device 21 is provided. This energy control device 21 is described, for example, in EP 898 291 A, the content of which is hereby made the content of this description by express reference. By a rotational movement of a knob 22 by an operator, a certain cooking level can be set, which determines the amount of power generation of the heater 13 and the average power. Usually this is divided into so-called cooking stages, for example in half steps from zero to nine. As a function thereof, the energy control device 21 switches the heating device 13 on or off in the predetermined on and off times with the illustrated switch, which corresponds to the first switching device described above.

The temperature limiter 23, which is shown surrounded by a broken line in a functional manner, is described in a similar manner, for example in the aforementioned DE 33 33 645 A. The temperature limiter 23 has a first switch 24, which corresponds to the abovementioned first switching device. Furthermore, it has a third switch 25, which speaks functionally of the aforementioned third switching device ent. This will be discussed in more detail later. In addition, the temperature limiter 23 has an elongated sensor 26, which consists of an outer sensor tube 27 and inner core arranged therein. ben 28a and 28b exists. Its function will be explained with reference to FIG. 4.

Depending on a temperature over the heating devices 13 and 15, which the sensor 26 detects, the first switch 24 is opened or closed. Up to a usually set temperature in the range 550 ⁰ C to 650 ⁰ C, the first switch 24 is closed and the power supply or the activation of the first heater 13 takes place exclusively via the energy control unit 21. If this limit temperature is exceeded, as will be described in more detail below ein¬ gone, the temperature limiter 23 opens the first switch 24 and the first heater 13 is turned off or deactivated.

Furthermore, the device 11 has a second heating device 15. These, like the first heating device 13, can also be designed as a radiant heater with the same clocking mode of operation. Via an additional switch 31, a basic activation of the second heating device 15 by the operator takes place. Furthermore, a power relay 32 is provided in the power supply, which corresponds to the aforementioned second switching device. Only when additional switch 31 and power relay 32 are closed is the second heating device 15 activated. To actuate the power relay 32, the temperature limiter 23 uses the third switch 25, which is usually provided for a hot indication, but not here. He corresponds here to the aforementioned third switching device. In this case, it can be provided that the power relay 32 can only close and thus activate the second heating device 15 when the temperature limiter 23 is connected to the supply voltage, ie when the energy control device 21 provides an on-time. The further rule here is that the first switch 24 and the third switch 25 are always opened or closed at the same time in each case, so that the heating devices 13 and 15 are in the case of common control. drive together and turn on or off simultaneously wer¬ the.

It may be provided in the respective control that the third switch 25 can only supply the power relay 32 with voltage when the first switch 24 is closed. It is thereby achieved that the power relay 32 can be activated depending on the switching state of the third switch 25 as well as on the switching state of the first switch 24 for switching on the second heating device 15.

FIG. 2 shows how the first heating device 13 as an inner heating circuit and the second heating device 15 as an outer heating circuit form a cooking position 19 of a hob 17 as an electrical appliance with a glass ceramic plate 18. The temperature limiter 23 extends with the sensor 26 from the outside once across a circular ring of the second heater 15 and fully on the first heater 13. In the area above the second heater 15, the sensor 26 is deactivated, which in conjunction with FIG is explained in more detail.

Furthermore, it is shown how the supply line to the first heating device 13 via the temperature limiter 23 and there the first switch 24 runs. It is the energy control unit 21 hen vorgese¬ with the knob 22, which is connected to the supply voltage and the hotplate 19 controls.

By way of the additional switch 31 mounted on the hob 17 and consisting of a control element accessible to an operator and a switch as shown, a fundamental connection of the second heating device 15 can take place. Furthermore, the power relay 32 can be controlled via the temperature limiter 23, like the first one _

Hθizeinrichtung 13, so as to connect the second heater 15 with the versor¬ supply voltage.

FIG. 3 shows the arrangement according to FIG. 2 in a lateral representation. Here it can be seen how the sensor 26 of the temperature limiter 23 extends above the heating devices 13 and 15, ie between them and the underside of the glass-ceramic plate 18. Since the distance of the heating devices 13 and 15 and of the sensor 26 to the underside of the glass-ceramic plate 18 is known , the temperature limiter 23 can be adjusted to a switch-off temperature or limiting temperature, which corresponds to a limit temperature, which is not to be exceeded, on the glass-ceramic plate 18.

FIG. 4 shows a detailed illustration of the temperature limiter 23 together with the sensor 26. With regard to the sensor 26, it can be said that it consists of an outer sensor tube 27 and two inner rods 28a and 28b. The sensor tube 27 is, for example, metallic and firmly attached to a housing of the temperature limiter 23. At the remote end of the sensor 26, which is not illustrated, the inner rod 28 and the guide tube 27 are connected to one another, for example clamped or by a stop. In the region above the first heating device 13, in which the sensor 26 is active or should detect the temperature, the inner rod 28a may be made of ceramic, that is, have a negligible temperature expansion coefficient. As the temperature increases, the sensor tube 27 expands considerably more than the inner rod 28a. As a result, a relative movement of the entire inner rod takes place relative to the sensor tube, as a result of which the switches 24 and 25 are moved or switched.

In order to deactivate the sensor 26 in the region above the second heating device 15, the inner rod 28b there consists of the same material as the sensor tube 27. Since its expansion coefficient then are exactly the same, can not contribute to the behavior of the sensor 26 and to the relative movement there occurring heat or prevailing there temperature.

The deactivation of the sensor 26 via the second heating device 15 has the purpose and can only be carried out if the power of the second heating device 15 is so low that it does not exceed a surface-specific heating power of about 2.5 W per cm ² . This has been done before. The choice of this heating power thus makes it possible to manage without temperature limitation in the region of the second heating device 15 and thus to require no temperature limiter. As a result, the total heating power of the cooking zone 19 which can reasonably be monitored only by a single temperature limiter in order to avoid unnecessary outlay can be set higher than would be possible if the entire flow was exclusively via the temperature limiter 23 would have to be switched. In this case, so to speak, the temperature governor 23 for the activation of the additional second heating device 15 is used only as a signaling control.

This division of the hotplate 19 into two heaters 13 and 15 may either be provided, as has been essentially described above, to provide a simple and meaningful power control depending on the size of the cooking vessel used. By way of the additional switch 31, an operator decides whether the second heating device 15 should be used for a corresponding cooking vessel.

Alternatively, it is possible not to use the two heating devices 13 and 15 with respect to variable size adaptation, but always to use them in order to combine as much heating power as possible in the then provided hotplate and furthermore only a single one - To -

Provide temperature limiter 23 and a single switch in the Energiesteu¬ ergerät 21. Then can be dispensed with the additional switch 31, and the second heater 15 is always switched on together with the first heater 13 at the same time or just turned off.

As an alternative to the arrangement of the heating devices 13 and 15 according to FIG. 2 as separate, surrounding zones, it is also possible, as it were, to mix them and to form substantially the same area covering each other.

Another alternative is shown in FIG. There is also dispensed with the power relay 32, wherein the third switch 25 ^' corresponds to the vorbe¬ prescribed second switching device, but the power for the second heater 15 switches directly. In this case, it is similar to the first switch 24 also designed as a circuit breaker. For this purpose, however, a conventional temperature limiter 23 is structurally modifiable in such a way, in particular with a certain expenditure, that two mains voltage switches or circuit breakers 24 and 25 'are contained in a housing. This makes it possible to dispense with the second power relay 32.

Another alternative arrangement 111 to that of FIG. 1 is shown in FIG. The control of the relay 132 is not made here via a further switching device in dashed symbolized Temperatur¬ limiter 123. At the switch 124, which corresponds to the switch 24 of Fig. 1, a contact P1 is provided. At these the relay 132 is connected. Thus, the switch 124 directly energizes both the heater 113 and the second heater 115 indirectly via the activation of the relay 132. Both heaters 113 and 115 are always in operation at the same time. The relay 132 corresponds to the second switching device according to the invention. Since the first shell ter 124 is triggered via the activation movement in the temperature limiter, this also triggers the relay 132 in the sense of the invention.

In an advantageous embodiment of the invention, therefore, a Ansteu¬ tion can be provided for switching on and off of two Heizeinrich¬ lines of a hob, which form a multi-circuit cooking. An energy control unit can be used to adjust the level of permanent energy or power generation in a pulsating manner. A temperature limiter monitors a maximum temperature over the first heating device, but not over the second heating device. The energy control device controls the first heating device directly or switches it on. The temperature limiter triggers a power relay in order to switch the second heating device simultaneously with the first heating device.

Claims

_ _Patent claims

1. Device (11, 111) for switching on and off of a plurality of heating devices (13, 113, 15, 115) of a cooking appliance (17), wherein the heating devices are arranged on the cooking appliance, the device comprising a temperature detection device ( 23, 123) with a temperature-dependent thermo-mechanical releasing movement for switching devices and a first switching device (24, 124), wherein the first switching device (24, 124) is connected to the temperature sensing device (23) for actuation for Switching on and off a first heating device (13, 113) directly by the triggering movement at an adjustable triggering point, the device (11, 111) having a second switching device (25 ^' , 32, 132) for switching on and off a second heating device ( 15, 115) of the cooking appliance (17), wherein the second switching device can be activated by the triggering movement.

2. Apparatus according to claim 1, characterized in that the second switching device is a relay (32, 132), which is vorzugswei¬ se open in the de-energized state.

3. Apparatus according to claim 1 or 2, characterized in that the second switching device (25 ^' , 32, 132) directly by the first switching means (24, 124) can be activated, preferably vorzugs¬ when the first switching means for turning on the first heating device (13, 113) the second switching device (25 ', 32, 132) receives an electrical signal or is supplied with energy from the connection of the first heating device to a supply voltage for activating the second heating device (15, 115) ,

, Apparatus according to claim 1 or 2, characterized by a third switching device (25) which is connected or coupled to the temperature sensing device (23) and directly actuated by the triggering movement at an adjustable trigger point bar, preferably simultaneously with the first heating device (13) at the same trigger point, wherein the third Schalteinrich¬ device (25) the second switching device (32) directly activated or energized to turn on or off the second Heizein¬ direction (15).

5. The device according to claim 4, characterized in that the third switching device (25) in the temperature sensing device (23) is included, preferably in the same housing as the first switching device (24).

6. Device according to one of the preceding claims, characterized in that the temperature detection device (23, 123) has an expansion device (26, 126) for the Aus¬ release movement as a rod controller with at least two elongate parallel pa¬ longitudinal elements (27 , 28) which have different coefficients of thermal expansion and whose differential expansion at a given temperature causes the triggering movement by coupling both longitudinal elements (27, 28) at a remote end, a longitudinal element on the temperature sensing device (23, 123 ) is fixed and the other moves relative to it and her¬ calls the triggering movement.

7. Device according to one of the preceding claims, characterized in that it comprises a control in the form ei¬ nes clocking energy control device (21, 121), the height of the Power generation at the heaters (13, 113, 15, 115) determined, with none of the switching devices (24, 124, 25, 32, 132) is activated or aktivier¬ bar when switched off control.

8. cooking appliance (17) with a device (11, 111) according to any one of the preceding claims and with at least two independently controllable heating means (13, 113, 15, 115) which form a cooking point (19) or ange¬ very close together ange¬ are arranged for at least occasionally joint activation or heating, wherein the first heating device (13, 113) is a main heating device and the second heating device (15, 115) is an additional heater.

9. Cooking appliance according to claim 8, characterized in that the second heating device (15, 115) surrounds the first heating device (13, 113) or adjoins it laterally.

10. Cooking appliance according to claim 8 or 9, characterized in that the power or power density of the first heating device (13, 113) is substantially greater than that of the second Heizein¬ direction (15, 115).

1 1. Cooking appliance according to one of claims 8 to 10, characterized by a clocking energy control unit (21, 121) which at least the first heating means (13, 113) on and off to achieve a certain power over a certain period of time, where the power is either zero or 100%.

12. Cooking appliance according to claim 11, characterized by a fourth switching device (31, 131) which, independently of the second switching device (25 ^' , 32, 132), the second heating device (15, 115) is activated or deactivated for simultaneous operation with the first heating device (13, 113) by the clocking energy control device (21, 121).

13. Cooking appliance according to one of claims 8 to 12, characterized gekenn¬ characterized in that the second switching device (25 ^' , 32, 132) is formed separately from the energy control device (21, 121) on the cooking appliance (17).

14. Cooking appliance according to one of claims 8 to 13, characterized gekenn¬ characterized in that the expansion device (26, 126) according to claim 6 An¬ covering the first heating device (13, 113), wherein the expansion device but not the second heating device (15, 115) is covered or at least deactivated in the region of the second heating device or one (28a) of the two longitudinal elements (27, 28) is replaced by a further longitudinal element (28b) which has the same temperature extension as the other Longitudinal element (27).