EP1917481B1 - Cooking appliance - Google Patents

Description

The present invention relates to a cooking appliance, in particular a high-installation cooking appliance, with at least one muffle defining a cooking space with a muffle opening, a drive device comprising a drive motor, a movable by means of this drive door door to close the muffle opening and a control circuit for driving the drive device, wherein the Door can only be moved if at least one safety signal activating the method is present. The present invention also relates to a method for operating a cooking appliance.

The WO 00/52392 A shows a device for the completion of the cooking process and the display of the state at the time of completion of the cooking program in a cooker for the preparation of food, which comprises a herd tube and a stove flap.

The DE 101 64 239 A1 shows a Hocheinbaugerät with a housing in which a muffle is provided. The muffle has a bottom-side muffle opening, which can be closed with a lowerable bottom door. The bottom door is connected via a bottom guide with the housing, with the aid of the bottom door is lowered via a stroke. The floor door guide has at least one housing-side first guide element and a bottom door-side second guide element.

From the JP 11 040332 A is a kiln for ceramic objects known.

US 3,735,750 A discloses a motor for moving a motorized door of a cooking appliance, a first switch and a second switch. The first switch is switchable by operating the motor and represents a limit switch, which occupies one of two positions depending on the end position of the door. The second switch is actuated by a thermocouple. The two switches and are electrically installed in series in a circuit of the motor.

DE 192 56 464 A1 discloses two sensor elements connected to a controller. If the sensor elements strike, the control device can provide a be triggered another function, which changes a standby level of controls.

DE 43 33 442 A1 discloses a switch-on for household appliances, in which an operation of the household appliance is accepted by an evaluation only when at least two independent, sensory monitorable switch input elements switch and / or IR sensors that are connected to the evaluation unit, are operated.

So far, high-installation cooking appliances are known in which a bottom door is moved by pressing a corresponding movement button in the desired direction.

For example DE 101 64 239 A1 a generic high-installation cooking appliance is known in which a control device controls the method of a bottom door.

The disadvantage is that a simple movement control of a door provides no protection against a malfunction of the control device and except for the Einklemmfall also provides no further protective measures for the operator.

It is therefore the object of the present invention to provide a cooking appliance, in particular a Hocheinbaugargerät with improved reliability in the process of the bottom door.

The present object is achieved by the cooking appliance having the features of patent claim 1 and a method according to claim 15.

For this purpose, the cooking appliance, which may be in particular a high-installation cooking appliance, but also a cooking appliance with a baking tray, constructed so that the door is movable only if there are at least two security signals, ie signals that enable certain functionalities hardware or software. Without the presence of the safety signals, no movement of the door is possible even if the travel switches are operated correctly. A security signal is output by a respective processor unit, typically a microcontroller, defined, which only in the proper state of the device electronics or the process of the door used electronics is possible. Also, compliance with other safety conditions can be implemented by the safety signal. The door can only be moved against an unwanted procedure if two safety signals are present together, which comprise a first, internal safety signal output by a first processor unit of a control circuit and a second, external safety signal output by a second processor unit of the control circuit, wherein the control circuit at least the first processor unit for actuating the drive motor of the drive device and the second processor unit for switching and / or regulating the first processor unit.

It is particularly advantageous if at least one of the safety signals is only present or produced when a temperature of the closed cooking chamber is below a temperature threshold, especially if the temperature threshold is 316 ° C. (600 ° F.) or 425 ° C. In this way it can be prevented that a user burns himself at a too hot oven part or a too hot food. It is equally advantageous if, in addition or alternatively, at least one of the safety signals is only present if a child safety device is not activated. This can prevent an unwanted procedure by children.

It is also advantageous if the security signals are pulsed signals, in particular square-wave signals, since this ensures the correct function when microcontrollers are used.

It is also advantageous if, in addition, a voltage supply of the drive device can be switched on by one of the safety signals, since this results in a dual safety function (switching on / activating the drive device).

It is advantageous for a secure and flexible construction if the control circuit comprises at least one lift plate for actuating the drive device and a control board for controlling, switching and / or regulating the lift circuit board. Then, advantageously, the first, internal safety signal is generated by the lift board and the second, external safety signal is generated by the control board. The internal safety signal is preferably applied by the lift board in response to a travel signal, e.g. B. an actuation of a movement panel or a movement command of a program automatic, generated. The external safety signal is conveniently generated by the control board only on request of the lift board. The control board is preferably connected to a temperature sensor for monitoring a temperature of the cooking chamber and / or a child safety device, so as to control the corresponding activatability / deactivability of the external safety signal. For this purpose, a hardware-implemented circuit for deactivating the external security signal is favorably available, which is switchable in particular by signals of the temperature sensor and / or the child safety device, z. B. by means of a safety relay. However, the activability / deactivability can also be ensured by a computer program product for deactivating the external security signal, which is likewise controllable in particular by signals from the temperature sensor and / or the child safety device.

According to the invention, the drive device comprises a drive motor, which can be activated by directional relays, which in turn are switchable by at least one transistor, since transistors are particularly simple, fast and inexpensive switchable by control signals.

1. (a) Erzeugen eines Anfahrsignals, insbesondere durch Betätigen mindestens eines Verfahrschaltfeldes;
2. (b) Empfangen des Anfahrsignals an der Liftplatine;
3. (c) Erzeugen eines internen Sicherheitssignals an der Liftplatine;
4. (d) Anfordern eines externen Sicherheitssignals von der Regelplatine durch die Liftplatine;
5. (e) Erzeugen eines externen Sicherheitssignals an der Regelplatine, falls keine Verriegelung vorliegt;
6. (f) falls keine Verriegelung vorliegt, Ausgeben des externen Sicherheitssignals an die Liftplatine und an eine Spannungsversorgung der Antriebsvorrichtung;
7. (g) Betreiben der Antriebsvorrichtung in die gewünschte Richtung durch die Liftplatine, solange sowohl das interne Sicherheitssignal als auch das externe Sicherheitssignal vorliegen.

A typical use case involves the following steps:

1. (A) generating a starting signal, in particular by actuating at least one traversing panel;
2. (b) receiving the start signal on the lift board;
3. (c) generating an internal safety signal on the lift board;
4. (d) requesting an external safety signal from the control board by the lift board;
5. (e) generating an external safety signal on the control board if no lock is present;
6. (f) if there is no lock, outputting the external safety signal to the lift board and to a power supply of the drive device;
7. (g) Operating the drive device in the desired direction through the lift board as long as both the internal security signal and the external security signal are present.

For ease of operation, the drive device is advantageously operable by operating both traversing panels even when the main switch is turned off.

• Fig. 1 eine perspektivische Ansicht eines an einer Wand montierten Hoch-Einbaugargeräts mit abgesenkter Bodentür;
• Fig. 2 eine perspektivische Ansicht des Hoch-Einhaugargeräts mit verschlossener Bodentür;
• Fig. 3 eine perspektivische Ansicht eines Gehäuses des Hoch-Einbaugargeräts ohne die Bodentür;
• Fig. 4 eine schematische Seitenansicht in Schnittdarstellung entlang der Linie I-I aus Fig. 1 des an die Wand montierten Hocheinbau-Gargerät mit abgesenkter Bodentür;
• Fig. 5 in Vorderansicht eine weitere Ausführungsform eines Hocheinbau-Gargeräts;
• Fig. 6 zeigt schematisch einen Aufbau einer Steuerschaltung in Bezug auf ein Verfahren der Bodentür.

The invention will be described in more detail below with reference to the attached schematic figures. Show it:

• Fig. 1 a perspective view of a wall-mounted Hoch-Einbaugargeräts with lowered bottom door;
• Fig. 2 a perspective view of the high-Einhaugargeräts with closed bottom door;
• Fig. 3 a perspective view of a housing of the Hoch-Einbaugargeräts without the bottom door;
• Fig. 4 a schematic side view in section along the line II Fig. 1 the wall-mounted high-installation cooking appliance with lowered bottom door;
• Fig. 5 in front view another embodiment of a high-installation cooking appliance;
• Fig. 6 schematically shows a structure of a control circuit with respect to a method of the floor door.

In the Fig. 1 a high-installation cooking appliance with a housing 1 is shown. The back of the housing 1 is mounted on a wall 2 in the manner of a hanging cabinet. In the housing 1, a cooking chamber 3 is defined, which can be controlled via a front side in the housing 1 introduced viewing window 4. In the Fig. 4 It can be seen that the cooking chamber 3 is bounded by a muffle 5, which is provided with a heat-insulating sheath, not shown, and that the muffle 5 is a bottom-side Muffelöffnung 6 has. The muffle opening 6 is closable with a bottom door 7. In Fig. 1 the bottom door 7 is shown lowered, being with its underside in abutment with a worktop 8 a kitchen equipment. To close the cooking chamber 3, the bottom door 7 is in the in the Fig. 2 shown position, the so-called "zero position" to adjust. To adjust the bottom door 7, the Hoch-Einbaugargerät a drive device 9, 10 on. The drive device 9, 10 has a in the Fig. 1 . 2 and 4 shown with dashed lines drive motor 9, which is arranged between the muffle 5 and an outer wall of the housing 1. The drive motor 9 is arranged in the region of the rear side of the housing 1 and stands, as in the Fig. 1 or 4 shown in operative connection with a pair of lifting elements 10 which are connected to the bottom door 7. It is according to the schematic side view of the Fig. 4 each lifting element 10 designed as an L-shaped carrier whose vertical leg extends from the housing-side drive motor 9. To adjust the bottom door 7 of the drive motor 9 can be actuated by means of a control panel 12 and a control circuit 13, which according to the Fig. 1 and 2 front side is arranged on the bottom door 7. As in Fig. 4 shown, the control circuit 13 is located behind the control panel 12 within the bottom door 7. The control circuit 13, which is composed here of several spatially and functionally separated and communicating via a communication bus circuit boards, is a central control unit for the device operation is and controls and / or regulates z. As a heating, a method of the bottom door 3, a conversion of user input, a lighting, a pinch protection, a clocking of the radiator 16, 17, 18, 22 and much more.

The Fig. 1 It can be seen that a top of the bottom door 7 has a hob 15. Almost the entire surface of the hob 15 is occupied by radiators 16, 17, 18, in Fig. 1 dash-dotted lines are indicated. In Fig. 1 the radiators 16, 17 are two spaced apart, different sized cooking surface heaters, while the radiator 18 is provided between the two cooking area heaters 16,17 surface heating element, which almost encloses the cooking surface heaters 16, 17. The hotplate heaters 16, 17 define for the user associated cooking zones or hobs; the hotplate heaters 16, 17 together with the surface heating element 18 define a bottom heat zone. The zones may be indicated by a suitable decoration on the surface. The radiators 16, 17, 18 are each controlled via the control circuit 13.

In the exemplary embodiment shown, the radiators 16, 17, 18 are configured as radiant heaters, which are covered by a glass ceramic plate 19. The glass ceramic plate 19 has approximately the dimensions of the top of the bottom door 7. The glass ceramic plate 19 is further equipped with mounting holes (not shown) through the base for holding support members 20 for Gargutträger 21 protrude, as well as in Fig. 4 shown. Instead of a glass ceramic plate 19, other - preferably quick-responding - covers can be used, for. B. a thin sheet.

With the help of a control panel 12 provided in the control knob, the high-installation cooking appliance can be switched to a cooking or a bottom heat mode, which will be explained below.

In the hob mode, the cooking surface heaters 16, 17 can be controlled individually by means of control elements 11, which are provided in the control panel 12, via the control circuit 13, while the surface heating element 18 remains out of operation. The hob mode is executable with lowered bottom door 7, as in Fig. 1 is shown. But it can also be operated with closed cooking chamber 3 with raised floor door 7 in an energy saving function.

In the lower heat mode, not only the hotplate heaters 16, 17 but also the surface heating element 18 are activated by the control device 13.

In order to achieve the most uniform possible tanning image of the food during the bottom heat, it is crucial that the cooking surface 15 providing the bottom heat has a uniform distribution of the heat output over the surface of the hob 15, although the heating elements 16, 17, 18 have different nominal powers. Preferably, therefore, the radiators 16, 17, 18 are not switched by the control circuit 13 to a continuous operation, but the power supply to the radiators 16, 17, 18 is clocked. The different sized nominal heating powers of the radiator 16, 17, 18 are individually reduced so that the radiators 16, 17, 18 provide a uniform over the surface of the hob 15 distribution of the heat output.

Fig. 4 schematically shows the location of a fan 23, z. B. for generating circulating air in a hot air operation or for supplying fresh air. In addition, a mounted on an upper side of the muffle 5 Oberhitzeheizkörper 22 is provided, the single-circuit or mehrkreisig, z. B. with an inner and an outer circle, can be executed. Also can - not shown here for clarity - another radiator such as a ring heater between the rear wall of the housing 1 and the muffle be present. By the control circuit 13, the various operating modes, such as, for example, top heat, hot air or Schnellaufheizbetrieb, by an appropriate activation and adjustment of the heating power of the radiator 16, 17, 18, 22, possibly with activation of the fan 23, are set. The adjustment of the heating power can be done by appropriate timing. In addition, the hob 15 can also be designed differently, for. B. with or without roasting zone, as a pure - one or mehrkreisige - warming zone without cooktops and so on. The housing 1 has a seal 24 towards the bottom door 7.

The control panel 12 is arranged mainly at the front of the bottom door 7. There are alternatively other arrangements conceivable, for. B. at the front of the housing 1, divided into different sub-fields and / or partially on side surfaces of the cooking appliance. Further designs are possible. The controls 11 are not limited in their design and can, for. B. z. As control knob, toggle switch, pushbuttons and membrane keys include the display elements 14 include z. B. LED, LCD and / or touchscreen displays.

In Fig. 5 is a schematic and not to scale a Hocheinbau-cooking appliance shown from the front, in which the bottom door 7 is open to rest with the worktop 8. The closed state is shown in dashed lines.

In this embodiment, two traversing panels 25 are located on the front side of the fixed housing 1. Each traversing panel 25 comprises two pushbuttons, namely an upper CLOSE button 25a for a bottom door 7 traveling upwards in the closing direction and a lower OPEN button 25b for one Without automatic operation (see below) moves the bottom door 7 only by continuous simultaneous pressing the CLOSE buttons 25a both traversing panels 25 upwards, if possible; also moves the bottom door 7 only by continuous simultaneous pressing of the UP buttons 25b both traversing panels 25 down, if possible (manual operation). Since in manual operation an increased operator attention of the user is given and also both hands are used here, an anti-trap is then optional. In an alternative embodiment, traversing panels 26 are mounted on opposite outer sides of the housing 1 with corresponding ZU buttons 26a and UP buttons 26b, as shown in dotted lines.

The dot-dashed control circuit 13, which is located inside the bottom door 7 behind the control panel 12, the drive motor 9 switches so that the bottom door 7 gently anfährt, d. H. not abruptly by simply hiring the drive motor 9, but by means of a defined ramp.

In this exemplary embodiment, the control circuit 13 comprises a memory unit 27 for storing at least one destination or travel position P0, P1, P2, PZ of the bottom door 7, preferably with volatile memory components, eg. B. DRAMs. If a target position P0, P1, P2, PZ is stored, the bottom door can move independently after actuation of one of the keys 25a, 25b and 26a, 26b of the traversing panels 25 and 26 in the set direction until the next target position is reached or one of the buttons 25a, 25b or 26a, 26b is pressed again (automatic mode). In this embodiment, the lowest target position PZ corresponds to the maximum opening, the (zero) position P0 corresponds to the closed state, and P1 and P2 are freely adjustable intermediate positions. If the last target position for one direction has been reached, manual operation must also be continued if this is possible (ie the last end positions do not correspond to a maximum open or closed final state). Analog must then, if for one direction no target position is stored - which z. B. for an upward movement into the closed position would be the case if only PZ is stored, but not P0, P1, P2 - are driven in this direction in manual mode. If no target position is stored, eg. B. in a new installation or after a power disconnection, no automatic mode is possible. If the bottom door 7 is moved in automatic mode, an anti-pinch protection is preferably activated. Automatic mode and manual operation are not mutually exclusive: by permanently actuating the positioning panel (s) 25, 26, the bottom door 7 also moves in manual mode if a target position could be approached in this direction. It can be z. B. a maximum actuation time of the traversing fields 25 and 26, respectively, of the associated keys 25a, 25b and 26a, 26b, are set to activate the automatic mode, z. B. 0.4 seconds.

A target position P0, P1, P2, PZ may be any position of the bottom door 7 between and including the zero position P0 and the maximum open position PZ. However, the maximum stored opening position PZ need not be the position with abutment on the work surface 8. Storing the target position P0, P1, P2, PZ can with the bottom door 7 at the desired target position P0, P1, P2, PZ, by, for example, lasting several seconds (eg, lasting two seconds), pressing a confirmation key 28 in the control panel 12th be performed. Existing optical and / or acoustic signal transmitters which output corresponding signals after storing a target position are not shown for the sake of clarity. A start-up of the desired target position P0, P1, P2, PZ to be set takes place, for example, by - in this embodiment - ambidextrous operation of the movement panels 25 or 26 and manual method to this position.

In the memory unit 27, only one or, as shown in this embodiment, a plurality of target positions P0, P1, P2, PZ can be einspeicherbar. In the case of several target positions P0, P1, P2, PZ, these can be approached successively by actuating the corresponding travel keys 25a, 25b or 26a, 26b. Through several target positions P0, P1, P2, PZ, the high-installation cooking appliance can be easily adapted to the desired operating height of multiple users. The target position (s) are advantageously erasable and / or overwritten. In one embodiment, for example, only one target position can be stored in the opened state, while the zero position P0 is automatically recognized and can be approached automatically. Alternatively, the zero position P0 must be stored in order to be automatically approachable.

It is particularly advantageous for ergonomic use if the or a target position P1, P2, PZ opens the bottom door 7 at least about 400 mm to about 540 mm (ie P1-P0, P2-P0, PZ-P0 ≥ 40cm to 54 cm). In this opening dimension are the Gargutträger 21 easy to use in the support members 20. It is advantageous if the viewing window 4 is mounted approximately at eye level of the user or slightly below, z. B. by means of a template that indicates the dimensions of the cooking appliance.

Not shown is an existing power failure override for bridging of about 1 to 3 s power failure, preferably up to 1.5 s power failure.

The drive motor 9 off Fig. 1 has at least one sensor unit 31, 32 on a motor shaft 30, possibly in front of or behind a transmission arranged to measure a travel or a position and / or a speed of the bottom door 7. For example, the sensor unit may include one or more induction, reverberation, opto, SAW sensors, and so forth. Here are for easy distance and speed measurement here two Hall (part) elements 31 offset by 180 ° - ie opposite - attached to the motor shaft 30, and a Hallmeßaufnehmer 32 is fixedly mounted at this area of the motor shaft spaced. If a Hall element 31 then moves past the measuring transducer 32 when the motor shaft 30 rotates, a measuring or sensor signal is generated which is, to a good approximation, digital. With (not necessarily) two Hall elements 31, therefore, two signals are output during one revolution of the motor shaft 30. By time evaluation of these signals, z. B. their time difference, the speed vL of the bottom door 7 can be determined, for example via comparison tables or a conversion in real time in the control circuit 13. By addition or subtraction of the measured signals, a travel or a position of the bottom door 7 can be determined.

A speed control can realize the speed, for example via a PWM-controlled power semiconductor.

For zero point determination, the distance measurement is automatically re-adjusted by initialization in the zero position P0 of the bottom door 7 at each start, so z. B. a faulty sensor signal output or recording is not traditional.

The drive motor 9 is operated by actuation of both traversing panels 25 and 26, even when the main switch 29 is turned off.

Instead of two separate switches per traversing field 25, 26 and a single switch per traversing field is possible, for. B. a toggle switch with a neutral position, which switches only under pressure. Other shapes are possible. Also, the nature and arrangement of the controls 28,29 of the control panel 12 is not limited.

The arrangement and distribution of the control circuit 13 is flexible and not limited, so it can be several boards, z. B. include a display board, a control board and an elevator board, which are spatially separated.

A 4 mm opening dimension can be detected by limit switches 33, which deactivate anti-pinch protection when actuated.

The high-installation cooking appliance can also be designed without a storage unit 27, in which case no automatic operation is possible. This can be for increased operating safety, eg. B. as protection against pinching, be useful.

Fig. 6 shows a schematic circuit diagram of the drive motor 9 connected to the control circuit 13. The control circuit 13 here consists of three separate boards or modules, namely an elevator board 34 for directly actuating the drive motor 9, a control board 35, inter alia, for switching and / or regulating the lift board 34 and a display board 36 for controlling the control panel 12, z. The display unit 14, and processing and / or routing of operating signals of the controls 11. The boards 34-36 are interconnected for communication via a DII bus 37; Therefore, the boards 34-36 may also be arranged at different locations in the cooking appliance, z. B. the display board 36 behind the panel 12, the control board 35 in the fixed part of the housing 1 and the lift board 34 in the vicinity of the drive motor. 9

The direction of movement of the drive motor 9 and thus the bottom door 3 is determined by two (not shown here) relays, which are controlled by transistors. If one of the relays is active, the drive motor 9 moves in the assigned direction. If both relays are active - which should normally be prevented - the drive motor blocks 9. If no relay is active, the motor 9 is short-circuited and no movement is possible (idle state). In this embodiment, the engine 9 are driven only if at least two safety signals are present; ie here, that only then the transistors can be controlled accordingly. A first safety signal is an (internal) safety signal S1 generated by the lift circuit board 34 itself, which, for. B. is generated with correct actuation of the movement or lift function, for example by pressing the traversing switches 25a, 25b, 26a, 26b. The first safety signal S1 ensures that a travel signal is correctly accepted and processed on the lift board 34 - that is, there is no fault-related switching of the relay by the lift board 34 - since otherwise the circuit for the safety signal, typically a microcontroller, would not trigger. Thus, this safety signal S1, that the electronics of the lift board basically works correctly. The second safety signal is an (external) safety signal S2 generated by the control board 35, which typically takes into account other states managed by the control board 35, e.g. B is a temperature in the closed cooking chamber 3 or an activation of a childproof lock 40. In this embodiment, the external safety signal S2 switches twice: first, the power supply of the relay and secondly together with the internal safety signal S1 the corresponding transistor. The safety signals S1, S2 are in this embodiment with 1 KHz clocked pulse signals ("Wigglersignale"), more precisely: square wave signals, which is advantageous because the most existing microcontroller must work properly.

A typical sequence of an actuation of the drive motor 9 is as follows: a user wants to open a closed cooking chamber 3, in which a prepared food is located, to remove the food. For this he presses one of the "UP" buttons 25b briefly in the automatic mode, ie shorter than 0.4 seconds. The actuation of the "UP" button 25b is sensed by the display board 36 and forwarded in this embodiment via the signal bus 37 to the lift board; Alternatively, the actuating signal S3 can be conducted via a direct line to the lift board 34. The lift board 34 detects the correct actuation signal S3, and generates the internal safety signal S1. In addition, the lift board 34 now requests the external security signal S2 via the bus 37 from the control board 35. The control board 35 checks whether a transmission of the external security signal S2 is not precluded by further conditions; it is first checked whether the child safety device 40 is turned off and second, whether a temperature sensor 39 indicates a temperature in the cooking chamber 3, which is less than a temperature threshold of z. B. 425 ° C or 316 ° C (600 ° F).

Only if no other conditions conflict, the external safety signal S2 is output. In this embodiment, the corresponding transistor and thus the corresponding directional relay via a control line 38 is driven only when both the internal security signal S1 and the external security signal S2 are present. By the external safety signal S2, the voltage supply of the relay is additionally enabled by switching on the transformer 41 for the drive motor 9. Only then can the drive motor 9 be actuated, and the bottom door 3 moves accordingly. The external safety signal S2 thus has a dual safety function. Alternatively, however, the external security signal S2 may also have only one of these functionalities. Before the bottom door 7 is moved, both relays are also checked for their functionality.

One of dem.Temperatursensor 39, z. As a Pt500 or Pt1000 temperature sensor, output temperature reading uses the control board 35, for example, to check whether the cooking chamber 3 is too hot to open. Is the temperature above a certain temperature threshold, z. B. 415 ° C or 316 ° C (600 ° F) so gives the control board 35 no external safety signal, and the bottom door 7 does not move (lock). This locking or deactivation of the external safety square signal S2 can be done via a hardware circuit, for. B. so that when exceeding the temperature threshold for switching the external safety signal S2 necessary switch forcibly opens or remains open. Alternatively, the locking can also be done programmatically.

The control circuit 13 may also be different or not at all divided, and the nature and arrangement of the interconnection and signal control is of course not limited to the cited embodiment. It can also be used more or less than two security signals, z. B. only safety signal S1 or S2, since even a security signal provides increased reliability in the process. Also, further safety conditions can be observed when moving the door.

Claims (15)

1. Cooking appliance having at least

   - a muffle (5) which delimits a cooking compartment (3) and has a muffle opening (6),

   - a drive device (9,10) comprising a drive motor (9),

   - a door (7) for closing the muffle opening (6), said door being movable by means of this drive device (9,10), and

   - a control circuit (13) for controlling the drive device (9,10),

   - wherein the door (7) can only execute a travel movement if at least one safety signal (S1,S2) activating the travel movement is present,
   characterised in that

   - the door (7) can only execute a travel movement if at least two safety signals (S1, S2) are present, wherein

   - the at least two safety signals (S1, S2) comprise a first internal safety signal (S1) output by a first process sensor unit of the control circuit (13), and a second external safety signal (S2) output by a second processor unit of the control circuit (13) and

   - the control circuit (13) comprises at least the first processor unit (34) for actuating the drive motor (9) of the drive device (9, 10) and the second processor unit for switching and/or regulating the first processor unit (34).
2. Cooking appliance according to claim 1, characterised in that the second safety signal (S2) is present only if a temperature of the closed cooking compartment (3) is below a temperature threshold value.
3. Cooking appliance according to claim 2, characterised in that the temperature threshold value is 316 °C (600 °F) or 425 °C.
4. Cooking appliance according to one of the preceding claims, characterised in that the second safety signal (S2) is present only if a child safety device (40) is not activated.
5. Cooking appliance according to one of the preceding claims, characterised in that the safety signals (S1, S2) are pulsed signals, in particular square wave signals.
6. Cooking appliance according to one of the preceding claims, characterised in that a voltage supply (38) for a drive motor (9) of the drive device (9,10) can be switched on by means of one of the safety signals.
7. Cooking appliance according to one of the preceding claims, characterised in that the internal safety signal (S1) can be generated in response to a travel movement signal (S3).
8. Cooking appliance according to one of the preceding claims, characterised in that the external safety signal (S2) can be generated in response to the first processor unit.
9. Cooking appliance according to one of the preceding claims, characterised in that the second processor unit is connected to a temperature sensor (39) for monitoring a temperature of the cooking compartment (3) and/or a child safety device (40).
10. Cooking appliance according to claim 9, characterised in that a circuit for deactivating the external safety signal (S2) is present which is switchable in particular by means of signals from the temperature sensor (39) and/or the child safety device (40).
11. Cooking appliance according to claim 9, characterised in that a computer program product for deactivating the external safety signal (S2) is present which can be controlled in particular by means of signals from the temperature sensor (39) and/or the child safety device (40).
12. Cooking appliance according to one of the preceding claims, characterised in that the drive device (9,10) includes the drive motor (9) which can be activated by means of directional relays which in turn are switchable in each case by means of at least one transistor.
13. Cooking appliance according to one of the preceding claims, characterised in that the processor unit (34-36) can communicate with one another by means of at least one bus line (37).
14. Cooking appliance according to one of the preceding claims, said cooking appliance taking the form of a high-level cooking appliance, characterised in that the muffle opening is a base-side muffle opening (6) and the door is a base door (7).
15. Method for operating a cooking appliance according to one of the preceding claims, characterised in that the method comprises the following steps:

    (a) generating a travel movement starting signal (S3), in particular by actuating at least one travel switch panel (25,26);

    (b) receiving the travel movement starting signal (S3) at the first processor unit (34);

    (c) generating an internal safety signal on the first processor unit (34);

    (d) requesting an external safety signal from the second processor unit (35) by the first processor unit (34);

    (e) generating an external safety signal (S2) on the second processor unit if no lock is present;

    (f) if no lock is present, outputting the external safety signal (S2) to the first processor unit (34) and to a voltage supply (38) for the drive device (9,10);

    (g) operating the drive device (9,10) in the desired direction by means of the first processor unit (34), provided both the internal safety signal (S1) and also the external safety signal (S2) are present.

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