Patent Application
20090229475
The present invention relates to a cooking appliance, in particular a high-level cooking appliance, having at least one muffle which delimits a cooking compartment and has a muffle opening, a door for closing the muffle opening, said door being movable by means of a drive device, and a control circuit for controlling the drive device.
Prior art high-level cooking appliances are known in which a base door can be caused to move in the desired direction by actuation of a corresponding travel button.
DE 101 64 239 A1, for example, discloses a generic high-level cooking appliance in which a control device controls the travel movement of a base door.
A disadvantage is that a simple door travel movement control of this kind affords no protection whatever against a malfunction of the control device and, with the exception of the pinching instance, also provides no further protective measures for the operator.
The object of the present invention is therefore to provide a cooking appliance, in particular a high-level cooking appliance, having improved operational safety during the travel movement of the base door.
The present object is achieved by means of the cooking appliance having the features recited in claim 1 and by means of a method as claimed in claim 18.
With that object in view, the cooking appliance, which is in particular a high-level cooking appliance but may also be a cooking appliance having a baking carriage, is designed in such a way that the door is only movable when at least one safety signal is present, which is to say a signal which activates specific functionalities by hardware or software means. Without the safety signal being present, no travel movement of the door is possible even when the travel switches are operated correctly. The safety signal is usually output by at least one processor unit, typically a microcontroller, in a defined manner, which is possible only if the device electronics or the electronics used for controlling the door's travel movement are in a proper condition. The safety signal can also be used to ensure compliance with further security conditions.
To provide an improved safeguard against unintentional travel movement, the door can beneficially be moved only if two safety signals are present together.
It is advantageous in particular if at least one of the safety signals is present or is generated only if a temperature of the closed cooking compartment is below a temperature threshold value, specifically if the temperature threshold value is 600° F. or 425° C. This can serve to prevent a user burning himself/herself on a part of the oven or on a dish that is too hot. It is equally advantageous if, in addition or alternatively, at least one of the safety signals is present only when a child safety device is not activated. By this means an unintentional travel movement triggered by children can be prevented.
It is also favorable if the safety signals are pulsed signals, in particular square wave signals, since in this way, when microcontrollers are used, their correct operation is ensured.
It is furthermore advantageous if a voltage supply for the drive device can additionally be switched on by means of one of the safety signals, since this results in a dual safety function (switching on/activation of the drive device).
It is advantageous for a safe, reliable and flexible design if the control circuit includes at least one lift board for actuating the drive device and a regulator board for controlling, switching and/or regulating the lift board.
Advantageously, a first, internal safety signal is generated by the lift board and a second, external safety signal is generated by the regulator board. The internal safety signal is preferably generated by the lift board in response to a travel movement signal S3, e.g. an actuation of a travel switch panel 25, 26 or a travel command of an automatic program. The external safety signal is favorably generated by the regulator board only at the request of the lift board. The regulator board is preferably connected to a temperature sensor for monitoring a temperature of the cooking compartment and/or to a child safety device in order thereby to control the corresponding activation/deactivation capability of the external safety signal. For this purpose a hardware-implemented circuit for deactivating the external safety signal is favorably present which is switchable in particular by means of signals from the temperature sensor and/or the child safety device, e.g. by means of a safety relay. However, the activation/deactivation capability can also be ensured by means of a computer program product for deactivating the external safety signal, which computer program product can likewise be controlled in particular by means of signals from the temperature sensor and/or the child safety device.
It is also advantageous if the drive device includes a drive motor which can be activated by means of directional relays which in turn are switchable in each case by means of at least one transistor, since transistors are particularly easy, quick and cheap to switch by means of control signals.
A typical application scenario comprises the following steps:
To simplify operator control, the drive device can advantageously be operated by actuating both travel switch panels even if the main switch is switched off.
The invention is described in greater detail below with reference to the attached schematic figures, in which:
It can be seen from
In the exemplary embodiment shown, the heating elements 16, 17, 18 are embodied as radiant heating elements which are covered by a glass ceramic plate 19. The glass ceramic plate 19 has approximately the dimensions of the top of the base door 7. The glass ceramic plate 19 is also equipped with mounting openings (not shown), through which sockets project for the purpose of holding support parts 20 for cooking item carriers 21, as is also shown in
With the aid of an operating knob which is provided in the operating panel 12, the high-level cooking appliance can be switched to a cooking position operating mode or an underside-heating operating mode, wherein these are explained below.
In the cooking position operating mode, the cooking position heating elements 16, 17 can be controlled individually via the control circuit 13 by means of operating elements 11 which are provided in the operating panel 12, while the surface heating element 18 remains unused. The cooking position operating mode can be implemented when the base door 7 is lowered as shown in
In the underside-heating operating mode, the control device 13 controls not only the cooking position heating elements 16, 17 but also the surface heating element 18.
In order to achieve a maximally even browning impression of the cooking item during the underside-heating operation, it is critical that the cooking matrix 15 which provides the underside heating exhibits an even distribution of the heat power output over the surface of the cooking matrix 15, even though the heating elements 16, 17, 18 have different nominal powers. Therefore the heating elements 16, 17, 18 are preferably not switched to a continuous operation by the control circuit 13, but the current supply to the heating elements 16, 17, 18 is timed. In this case, the different nominal heating powers of the heating elements 16, 17, 18 are reduced individually in such a way that the heating elements 16, 17, 18 provide an equal distribution of the heating power output over the surface of the cooking matrix 15.
In this embodiment there are two travel switch panels 25 on the front side of the permanently attached housing 1. Each travel switch panel 25 comprises two pushbuttons, specifically an upper CLOSE pushbutton 25a which causes a base door 7 to travel upward in a closing direction, and a lower OPEN pushbutton 25b which causes a base door 7 to travel downward in an opening direction. Without automatic operation (see below) the base door 7 only travels upward as a result of continuous simultaneous depression of the CLOSE buttons 25a of both travel switch panels 25, if possible; the base door 7 also only travels downward as a result of continuous simultaneous depression of the OPEN buttons 25b of both travel switch panels 25, if possible (manual operation). Since increased operating alertness on the part of the user is assumed in the case of manual operation, and both hands are also used here, pinching protection is only optional. In the case of an alternative embodiment, travel switch panels 26 are attached on opposite external sides of the housing 1 and have corresponding CLOSE buttons 26a and OPEN buttons 26b, as drawn using dotted lines.
The control circuit 13, which is drawn using dash-dotted lines and is located in the interior of the base door 7 behind the operating panel 12, switches the drive motor 9 in such a way that the base door 7 begins to move gently, i.e. not abruptly by simply starting 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 a destination or travel position P0, P1, P2, PZ of the base door 7, preferably using volatile memory modules, e.g. DRAMs. If a destination position P0, P1, P2, PZ is stored, following actuation of one of the buttons 25a, 25b or 26a, 26b of the travel switch panels 25 or 26, the base door can travel independently in the selected direction until the next destination position has been reached or until one of the buttons 25a, 25b or 26a, 26b is actuated again (automatic operation). In this exemplary embodiment, the lowermost destination position PZ corresponds to the maximum opening, the (zero) position P0 corresponds to the closed state, and P1 and P2 are freely selectable intermediate positions. If the last destination position for a direction has been reached, manual operation is additionally necessary for further travel, if possible (i.e. if the last final positions do not correspond to a maximally open final state or to the closed final state). Similarly, if no destination position is stored for a direction (which would be the case e.g. for an upward movement into the closed position if only PZ is stored but not P0, P1, P2), movement in this direction requires manual operation. If no destination position is stored, e.g. in the case of a new installation or following a power disconnection, no automatic operation is possible. If the base door 7 is to travel using the automatic operation, pinching protection is preferably activated.
Automatic operation and manual operation are not mutually exclusive: as a result of continuous actuation of the travel switch panel(s) 25, 26, the base door 7 also moves in manual operation if a destination position is nonetheless available in this direction. In this case, it is possible to define e.g. a maximum actuation time of the travel panels 25 or 26, or of the associated buttons 25a, 25b and 26a, 26b respectively, for the purpose of activating the automatic operation, e.g. 0.4 seconds.
A destination position P0, P1, P2, PZ can be any desired position of the base door 7 between and including the zero position P0 and the maximum opening position PZ. However, the maximum stored opening position PZ does not have to be the position which is in contact with the work surface 8. Storage of the destination position P0, P1, P2, PZ can be carried out with the base door 7 at the desired destination position P0, P1, P2, PZ by means of e.g. actuating a confirmation button 28 in the operating panel 12 for several seconds (e.g. two seconds). For the sake of greater clarity, available optical and/or acoustic signal emitters which output corresponding signals following storage of a destination position are not drawn. Arriving at the desired destination position P0, P1, P2, PZ to be set is achieved e.g. by means of—in this exemplary embodiment—two-handed operation of the travel switch panels 25 or 26 and manual travel to this position.
It is possible to store just one or, as shown in this exemplary embodiment, also a plurality of destination positions P0, P1, P2, PZ in the memory unit 27. In the case of a plurality of destination positions P0, P1, P2, PZ, these can be reached successively by actuating the corresponding travel buttons 25a, 25b or 26a, 26b. By virtue of a plurality of destination positions P0, P1, P2, PZ, the high-level cooking appliance can easily be adjusted to the desired operating height of a plurality of users. The destination position(s) can advantageously be deleted and/or overwritten. In one embodiment, for example, only one destination position in the open state can be stored, while the zero position P0 is detected automatically and can be reached automatically. Alternatively, the zero position P0 must also be stored in order that it can be reached automatically.
For ergonomic use it is particularly advantageous if the or a destination position P1, P2, PZ opens the base door 7 at least approximately 400 mm to approximately 540 mm (i.e. P1-P0, P2-P0, PZ-P0≧40 cm to 54 cm). At this opening distance, the cooking item carriers 21 can easily be inserted into the support parts 20. In this case, it is advantageous if the viewing window 4 is mounted at approximately eye level of the user or somewhat lower, e.g. by means of a template which indicates the dimensions of the cooking appliance.
A power failure protection for bridging power outages lasting approximately 1 to 3 s, preferably up to 1.5 s, is present but not illustrated.
The drive motor 9 from
A speed regulator can realize the speed e.g. via a PWM-controlled power semiconductor.
In order to determine the zero point, the displacement measurement is automatically reset by initializing in the zero position P0 of the base door 7 at each start-up, in order that e.g. an erroneous sensor signal output or sensor signal pick-up is not perpetuated.
The drive motor 9 can be operated by actuating both travel switch panels 25 or 26 even if the main switch 29 is switched off.
Instead of two separate switches per travel panel 25, 26, a single switch per travel panel is also possible, e.g. a tumbler switch which has a neutral position and only switches under pressure. Other forms are also possible. The type and arrangement of the operating elements 28, 29 of the operating panel 12 are likewise not restricted.
The arrangement and distribution of the control circuit 13 is flexible and not restricted in this case, and can therefore comprise a plurality of boards, e.g. a display board, a control board and a lift board, which are physically separate.
A 4-mm opening can be detected by stop switches 33 which, when actuated, deactivate a pinching protection.
The high-level cooking appliance can also be embodied without a memory unit 27, in which case no automatic operation is then possible. This can be suitable for increased operating safety, e.g. as protection against pinching.
The direction of the travel movement of the drive motor 9 and consequently of the base door 3 is determined by two relays (not shown in the figure) which are controlled by means of transistors. If one of the relays is active, the drive motor 9 travels in the assigned direction. If both relays are active—something which should be prevented under normal conditions—the drive motor 9 blocks. If no relay is active, the motor 9 is short-circuited and no travel movement is possible (idle state). In this exemplary embodiment the motor 9 can only be driven if at least two safety signals are present; which is to say in this case that only then can the transistors be triggered accordingly. A first safety signal is a(n) (internal) safety signal S1 which is generated by the lift board 34 itself and is generated e.g. upon correct actuation of the travel movement or lift function, for example by actuation of the travel switches 25a, 25b, 26a, 26b. The first safety signal S1 ensures that a travel movement signal is correctly received and processed on the lift board 34—i.e. that no error-induced switching of the relays by the lift board 34 is present—as otherwise the circuit for the safety signal, typically a microcontroller, would not trigger. Accordingly, this safety signal S1 includes that the lift board electronics are basically operating correctly. The second safety signal is a(n) (external) safety signal S2 which is generated by the regulator board 35 and typically takes into account further states managed by the regulator board 35, e.g. a temperature in the closed cooking compartment 3 or an activation of a child safety device 40. In this embodiment the external safety signal S2 produces a dual activation: firstly the voltage supply for the relays and secondly, in conjunction with the internal safety signal S1, the corresponding transistor. In this exemplary embodiment the safety signals S1, S2 are pulse signals (“wiggler signals”), more precisely: square wave signals, clocked at 1 KHz, which is advantageous, since most available microcontrollers must operate correctly for this.
A typical sequence of an actuation of the drive motor 9 takes place as follows: a user wishes to open a closed cooking compartment 3 containing a prepared dish in order to remove said dish. For that purpose he/she briefly, i.e. for less than 0.4 seconds, presses one of the “OPEN” buttons 25b in the automatic mode of operation. The actuation of the “OPEN” button 25b is sensed by the display board 36 and in this exemplary embodiment is forwarded via the signal bus 37 to the lift board; alternatively the actuation signal S3 can be routed 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 safety signal S2 from the regulator board 35 via the bus 37. The regulator board 35 checks whether any further conditions oppose a transmission of the external safety signal S2; thus, a check is made to verify firstly whether the child safety device 40 is switched off and secondly whether a temperature sensor 39 indicates a temperature in the cooking compartment 3 that is lower than a temperature threshold value of e.g. 425° C. or 600° F. The external safety signal S2 is output only if there are no further opposing conditions. In this embodiment the corresponding transistor and hence the corresponding directional relay are only triggered via a control line 38 if both the internal safety signal S1 and the external safety signal S2 are present. By means of the external safety signal S2 the voltage supply for the relays is activated in addition by switching-on of the transformer 41 for the drive motor 9. Only then can the drive motor 9 be actuated, and the base door 3 executes a travel movement accordingly. The external safety signal S2 thus has a dual safety function. Alternatively, however, the external safety signal S2 may also have only one of these functionalities. Furthermore, before the travel movement of base door 7 is initiated, both relays are additionally checked to verify their functionality.
The regulator board 35 uses a temperature measurement output by the temperature sensor 39, e.g. a Pt500 or Pt1000 temperature sensor, to check, for example, whether the cooking compartment 3 is too hot to be opened. If the temperature is above a certain temperature threshold value, e.g. 415° C. or 600° F., the regulator board 35 does not output an external safety signal and the travel movement of the base door 7 is not triggered (locking). This locking or, as the case may be, deactivation of the external safety square wave signal S2 can be effected by way of a hardware circuit, e.g. in such a way that if the temperature threshold value is exceeded, a switch required for switching the external safety signal S2 is forced to open or remains open. Alternatively the lock can also be applied under program control.
The control circuit 13 may also be subdivided differently or not be subdivided at all. Obviously, the type and arrangement of the circuitry and signal controller are also not limited to the exemplary embodiment described. Furthermore, more or fewer than two safety signals may be used, e.g. only safety signal S1 or S2, since even just one safety signal provides increased functional safety when travel movements are executed. It is also possible that further safety conditions are to be complied with during travel movements of the door.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2005 038 881.7 | Aug 2005 | DE | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2006/064659 | 7/26/2006 | WO | 00 | 2/14/2008 |
