Cooking Appliance, Especially Built-In Wall Cooking Appliance, and Method For Controlling a Cooking Appliance

Abstract

A cooking appliance including a high-level cooking appliance having a muffle including a muffle compartment defining a cooking compartment with a muffle opening, a door for movement between an open and closed relationship with the muffle opening and a drive device controlled by a control device for moving the door, the cooking appliance including a detector for determining a trapping condition wherein an object becomes trapped as the door is being moved, wherein the detector is configured for detecting the trapping state by comparing a door movement parameter with a threshold value associated with door movement.

Description

The present invention relates to a cooking appliance, especially a high-level cooking appliance, with at least one muffle delimiting a cooking compartment which has a muffle opening, a door for closing off the muffle opening and a drive device controlled by a control device for moving the door.

A high-level cooking appliance is known from DE 102 28 140 A1 in which the trapping of objects at the base unit door can be detected by a number of anti-trap protection switches, able to be operated independently of each other, between the base unit door and the muffle frame. In this case an increase in pressure in a door seal with a hollow profile can also be evaluated.

An anti-trap protection system which is initiated by different tensions on pull cables driving the base unit door is described in DE 101 64 239 A1. A torque sensor is also described, which detects a load moment on the drive shaft of an electric motor. Tension sensors, piezoelectric sensors and also deformation or strain/expansion sensors are listed as sensors for this purpose.

DE 102 88 141 A1 also describes an optoelectronic sensor for detecting a trapping condition, which uses the amount of reflected light for switching.

The disadvantage is that the anti-trap detection systems described are either relatively slow (tension sensor) or imprecise or error-prone (opto sensor) and also require increased installation effort.

Also the primary disadvantage of anti-trap protection systems is that an instance of a small and elastic object becoming trapped, for example a child's finger, is not detected or is only detected after an the object has sustained injury by being squashed too much. A further disadvantage lies in the fact that, especially in the case of end-position switches or anti-trap switches built into the front side of the cooking appliance, if a heavy load is placed on the door, bending causes its front edge to be lower than its rear edge, so that the switches may possibly not function absolutely securely.

Another disadvantage here is an activation of a closing process for the door, in which, shortly before the closed state is reached, a switchover is performed from anti-trap operation in which a switch or a function is used to detect a trap condition, to a closure mode for detecting the closed state.

The object of the present invention is thus to provide a fast, simple and accurate anti-trap detection system for a cooking appliance of the type described above.

The present object is achieved by the cooking appliance with the features of claim 1 and a method as claimed in claim 27.

The preference is thus for a cooking appliance, especially a high-level cooking appliance, with at least one muffle delimiting a cooking compartment which has a muffle opening, a door for closing off the muffle opening and a drive device controlled by a control device for moving the door whereby, in the event of an object being trapped when the door is moved, a trapping condition is detected, with the trapping condition being detected by comparing a parameter pertaining to a displacement movement of the door with a threshold value belonging to this parameter and by the system detecting when this threshold has been reached and/or exceeded. Exceeded in this case means that the value is exceeded from below or above (also called undershooting). In such cases the comparison between the current value and threshold value always relates to the current direction of movement of the door, i.e., that the speed comparison is undertaken independently of the direction of movement, meaning that it relates above all to the absolute speed. In the same sense it is assumed, that in the case of positive acceleration (acceleration) of the door Δv or Δv/Δt>0, whereas with negative acceleration (braking) Δv or Δv/Δt<0.

The threshold value preferably corresponds to a permitted minimum speed and/or a differential speed or speed difference per unit of time or acceleration. Such a threshold value can be employed as an additional or independent criterion. A differential speed can in this case be determined easily by an increase in the duration of a measuring signal of a Hall sensor for monitoring the rotation of a drive shaft. Also usable are further parameters such as a motor current or a load of the base unit door.

The threshold value can be determined as the difference from the setpoint value (e.g. threshold speed vS<setpoint speed vR*x %), so that the trapping condition is detected if the current speed vL of the base unit door reaches threshold value vS or exceeds it from above, i.e. falls below it, if is moving at only x % of the setpoint speed. This corresponds to the condition vS≧vL. Likewise the threshold value can be determined as the difference between the threshold value differential speed vS as setpoint differential speed ΔvR*y %, so that trapping is detected if the current differential speed ΔvL or acceleration of the base unit door reaches the threshold value ΔvS or exceeds it from above, i.e. undershoots it, if it is only still moving at y % of the setpoint speed. In this case a faster braking than intended (as in the case of trapping), means that the trapping condition ΔvS≧ΔvL is triggered for a predetermined period of time. The threshold value preferably depends on the setpoint value, i.e. that vS=vS(vR) or ΔvS=ΔvS(ΔvR) can apply for example. However a fixed predetermined threshold value can also be assumed, for example, If this anti-trap protection system is only applied in sections, e.g. only in an area of a ramp or in the area of a constant setpoint speed. For example the threshold value can then be predetermined as a fixed value in relation to the setpoint speed actually reached most (e.g. vR=50 mm/s), e.g. in a memory unit of a control unit, e.g. vS=40 mm/s. This can be prespecified for a number of sections, e.g. from a lookup table.

Monitoring a differential speed is especially advantageous in respect of a partly elastic and small object such as a child's finger becoming trapped. In such a case the door does not brake abruptly under some circumstances, which would be able to be detected securely with a pure speed monitoring method. Monitoring of the differential speed may be more sensitive here. Especially preferable is a combination of the two methods.

The monitoring of the trapping condition depending on the threshold value is preferably activated within a predetermined movement path of the door. If this movement path of the door especially lies within the last movement path before a zero position, which corresponds to a closing position of a closed door, an area can also be monitored in which for example an end switch has already been activated or other methods for monitoring a trapping condition can no longer be used. The trapping condition is preferably monitored within the last 15 mm, especially 10 mm, especially 5 mm of movement path of the door before the zero position is reached. Activation of the end switch in this case is to be understood not only as the detection of a secure end closed position but optionally also a first activation even before the final closed position of the door on reaching a specific approach distance of the door from the muffle.

The monitoring of the trapping condition depending on the threshold value is especially active after a deactivation of a first trapping condition monitoring method, i.e. continues to be activated or is switched on at this point. When the door approaches the muffle at a distance of less than especially 1 cm, there can be a secure switchover of an activation of a closure process for the door from an anti-trap protection mode in which a switch or a function serves to detect the trapping state, to a closure mode for securely detecting a closed state. This is secure because, after the switchover, continued monitoring is still undertaken alternately or at least by monitoring the closure speed. The monitoring of the trapping state depending on the threshold value is undertaken accordingly in this case especially after a switchover of a first monitoring type for monitoring a trapping state by means for example of switches shortly before a final closure movement of the door.

Advantageously, even after deactivation of a monitoring method depending especially on a constant speed also especially during braking of the door, i.e. during speed which changes over time, an anti-trap protection method can be provided.

The monitoring of the threshold value is preferably activated after activation of an end switch for signaling of a last closure area, so that an anti-trap protection method can be provided even in a narrow space in which a child's finger could be trapped.

The monitoring of the trapping state depending on the threshold value during a switchover to a force-regulated closure movement of the door is then activated especially if the final closure process is no longer regulated by speed but by force.

To this end the cooking appliance, which is especially a high-level cooking appliance, but can also be a cooking appliance with an oven carriage, is equipped with a speed measurement device for determining speed of movement of the door. The speed measurement device allows the detection of an object being trapped in the door by monitoring its speed of movement. In this case the displacement movement does not have to be speed-regulated, but can for example also be regulated depending on the load via the motor voltage or the motor current. Advantageously however the displacement movement of the door is also controlled or regulated as a function of the speed—i.e. also independent of the load, e.g. via a central control unit.

It is especially useful when the door is being closed for there to be at least one end switch also present, which is arranged in the area between muffle opening or frame and door, with an activation of the at least one end switch deactivating the anti-trap protection device or a first, other type of anti-trap protection, i.e. ending the protective measures. This end switch preferably switches at an opening distance of less than one centimeter, especially in a range of 9-4 mm, which is so small that none of the usual objects in the household could be trapped within the space. On activation of the at least one end switch the door is pushed with a defined force—and no longer speed-controlled—onto the muffle opening. Despite this it is advantageously guaranteed that when the door is closed, it does not reverse in an undesired manner, but in the case of a possible trapping of an object in the end phase of the closure, can still reverse.

In particular a non-abrupt premature stopping of the closing movement represents an indication of a trapped child's finger, so that the door is immediately opened again in such a case, especially by an opening distance sufficient to allow the finger to be pulled out. Such a non-abrupt premature stopping of the closure movement can be detected especially safely by monitoring a speed differential value.

To avoid even smaller objects or especially a child's finger becoming trapped however, there is preferably no complete deactivation provided but a switchover to a modified protection is undertaken.

This speed-based anti-trap protection method has the advantage of reacting comparatively fast, of being able to receive precise input data and of being able to be implemented relatively simply without any great constructional measures.

The monitoring of the speed of movement can be directed to reducing the speed of movement which is uncontrolled and thus not deliberately included in the regulation. This can occur by a value measured by the speed measurement device deviating by a percentage value from a setpoint value. If the deviation is above or below a specific threshold value, it is assumed that something has become trapped. For example if a door can no longer be moved at the setpoint speed selected since an object is preventing it from doing so, then the speed falls accordingly. This evaluation and monitoring can be undertaken in a central control device for example, e.g. via suitable microcontrollers.

As an alternative or in addition a—mostly too rapid—change of the speed of movement over time can trigger the anti-trap system, if for example the door is braked more quickly than provided for in the event of an object becoming trapped.

Naturally the values are selected so that speed fluctuations caused by the process for regulating the movement of the door do not generally activate the anti-trap system. In addition the anti-trap protection methods described in the prior art can also be used, such as measuring the motor current.

It is advantageous for the speed measurement device to include at least one sensor on a motor shaft of the drive device, especially of a drive motor, through which corresponding sensor signals are generated as the motor shaft turns. This makes a comparatively fast reaction possible. The sensor signals are directly or indirectly a measure of the speed of movement of the door. It is then especially useful for the at least one sensor to be a Hall sensor which outputs two sensor signals per revolution of the motor shaft. The Hall sensor system is simple to install, fast and insensitive. Advantageously two Hall (part) elements are accommodated on the motor shaft, so that two signals are output for one revolution of the motor shaft. By evaluating these signals over time a speed of the base unit door can be determined, for example using comparison tables or real time conversion. Preferably the speed of movement is detected by a time difference between the sensor signals.

For stable speed determination it is useful for a number, especially more than two, sensor signals to be evaluated. It is also advantageous here for a number, especially more than two, sensor signals to be averaged.

In particular it is advantageous for the direction of movement of the door to be reversed after detection of the trapping.

To this and an anti-trap protection device can be present which takes over the monitoring of the trapping condition and/or implementation of measures to be performed in the event of an object becoming trapped. The anti-trap protection device can be a separate device or be integrated functionally into existing control circuits, e.g. in the central control circuit or in a control board or a lift board.

It is useful for the anti-trap protection function or device to only be activated if a setpoint movement value, especially a setpoint speed, of the door is reached, which reduces the danger of a false triggering of anti-trap protection.

To protect the object that has become trapped in the door, a maximum force time curve is not exceeded by the door. Trapping ‘at’ the door includes an object being trapped between the door and an outside limit, e.g. the work surface, and also becoming trapped between door and muffle frame or housing. Different force time curves are provided for the two cases.

It is especially useful, when the door is being closed, for at least one end switch to be present, which is arranged in the area between muffle opening or frame and door, with an activation of the at least one end switch deactivating the anti-trap device or the anti-trap protection, i.e. stopping protective measures. This end switch typically switches at an opening distance of 4-9 mm, which is so small that objects can no longer become trapped. On the other hand this ensures that there is no undesired reversing of the door while it is closing. On activation of the at least one end switch the door is pushed with a defined force—and no longer speed-controlled—onto the muffle opening. It is still advantageous however for a threshold-activated anti-trap protection system—i.e. speed-dependent—to remain active.

The speed measurement device can however also be used for other purposes, such as setting the speed of movement of the door. This alone is not yet known nor is it suggested.

The invention is especially for high-level cooking appliances, in which the muffle opening is a floor-side muffle opening and the door is a base unit door which preferably moves in a linear manner.

The invention will be explained in detail below with reference to the enclosed schematic figures. The figures show:

FIG. 1 a perspective view of a high-level cooking appliance mounted on a wall with lowered base unit door;

FIG. 2 a perspective view of the high-level cooking appliance with closed base unit door;

FIG. 3 a perspective view of a housing of the high-level cooking appliance without the base unit door;

FIG. 4 a schematic side view in cross-section along the line I-I from FIG. 1 of the wall-mounted high-level cooking appliance with lowered base unit door;

FIG. 5 a front view of a further embodiment of a high-level cooking appliance;

FIG. 6 to 11 diagrams of displacement movements of a base unit door under different general conditions;

FIGS. 12 and 13 force time profile curves for a base unit door; and

FIG. 14 a diagram of a preferred displacement movement when a thin object becomes trapped between a base unit door and a muffle.

FIG. 1 shows a high-level cooking appliance with a housing 1. The rear of the housing 1 is mounted on a wall 2 in the manner of a wall-mounted cupboard. A cooking compartment 3, which can be checked via a viewing window 4 set into the front of the housing 1, is defined in the housing 1. It can be seen from FIG. 4 that the cooking compartment 3 is delimited by a muffle 5, which is provided by a heat-insulating jacket not shown in the figure, and that the muffle 5 features a muffle opening 6 on the floor side. The muffle opening 6 can be closed by a base unit door 7. FIG. 1 shows the base unit door 7 in a lowered position, in which its lower side is in contact with a work surface 8 of a kitchen unit. To close off the cooking compartment 3, the base unit door 7 should be moved into the position shown in FIG. 2 known as the “zero position”. To adjust the position of the base unit door 7 the high-level cooking appliance has a drive apparatus 9, 10. The drive apparatus 9, 10 has a drive motor 9, shown in FIGS. 1, 2 and 4 by the dashed outline, which is arranged between the muffle 5 and an outer wall of the housing 1. The drive motor 9 is arranged in the area of the rear of the housing 1 and, as shown in FIG. 1 or 4, is actively connected to a pair of lifting elements 10, which are connected to the base unit door 7. In this case, as depicted in the schematic side view shown in FIG. 4, each lifting element 10 is designed as an L-shaped support, of which the vertical arm extends downwards from the housing-side drive motor 9. To position the base unit door 7 the drive motor 9 can be actuated with the aid of a control panel 12 and a control switch 13 which is arranged as shown in FIGS. 1 and 2 on the front of the base unit door 7. As shown in FIG. 4, the control circuit 13 is located behind the control panel 12 within the base unit door 7. The control circuit 13, which consists here of a number of circuit boards in different locations and performing different functions, and communicating via a central communication bus, represents a central control unit for appliance operation and controls and/or regulates for example heating up, a movement of the base unit door 3, implementation of user entries, an illumination, anti-trap protection, timing of the heating elements 16, 17, 18, 22 and much more besides.

It can be seen from FIG. 1 that an upper side of the base unit door 7 features a cooking zone 15. Almost the entire surface of the cooking zone 15 is taken up by heating elements 16, 17, 18 which are shown as dashed outlines in FIG. 1. In FIG. 1 the heating elements 16, 17 are two separate different-sized hotplate elements, whereas heating element 18 is a radiant heating element provided between the two hotplate heating elements 16, 17 which practically surrounds the hotplate heating elements 16, 17. Hotplate heating elements 16, 17 define associated heating zones or heating areas for the user; the hotplate heating elements 16, 17 together with the radiant heating elements 18 define a lower heating zone. The zones can be shown by a suitable decor on the surface. Heating elements 16, 17, 18 can each be activated via the control circuit 13.

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 same dimensions as the upper side of the base unit door 7. The glass ceramic plate 19 is also equipped with installation openings (not shown), through which sockets for holding holder elements 20 for pot supports 21 extend, as shown in FIG. 4. Instead of a glass ceramic plate 19 other—preferably fast-response—covers can also be used, e.g. a thin metal sheet.

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

In the hotplate operating mode the hotplate heating elements 16, 17 can be activated individually by means of control elements 11, which are provided in the control panel 12, via the control circuit 13, whereas the radiant heating element 18 remains inoperative. The hotplate operating mode can be executed with the base unit door 7 lowered as shown in FIG. 1. It can however also be operated in a closed cooking space 3 with a raised base unit door 7 in an energy saving function.

In the bottom heat operating mode, not only the hotplate heating elements 16, 17 but also the radiant heating element 18 is activated by the control circuit 13.

In order to achieve the most even possible browning profile of the food being cooked during bottom heat operation, it is of decisive importance for the cooking zone 15 providing the bottom heat to have an even distribution of the heat power output over the surface of the cooking zone 15, although the heating elements 16, 17, 18 have different rated outputs. Preferably the heating elements 16, 17, 18 are thus not switched on permanently by the control circuit 13 but the power supply to the heating elements 16, 17, 18 is timed. In this case the different levels of rated heating power of the heating elements 16, 17, 18 are reduced so that the heating elements 16, 17, 18 create an even distribution of the heating power output over the surface of the cooking zone 15.

FIG. 4 is a schematic diagram of the position of a fan 23, for creating air circulation for example in a hot air mode or for supplying fresh air. In addition an overhead heating element 22 mounted on an upper side of the muffle 5 is provided which can be embodied with a single circuit or with multiple circuits, e.g. with an inner and an outer ring. Further heating elements—not shown here for reasons of clarity—such as a ring heating element between the rear wall of the housing 1 and the muffle can also be present here. Through the control circuit 13 the different operating modes such as overhead heating, hot air heating or rapid heating up mode can also be set for example by the corresponding switching on and switching off of the heating output of the heating element 16, 17, 18, 22, if necessary with activation of the fan 23. The heat power can be set by suitable timing. In addition the cooking zone 15 can also be of a different design, e.g. with or without an extended cooking zone, as a pure—single or multi-circuit heat retention zone without cooking areas and so forth. The housing 1 has a seal 24 against the base unit door 7.

The control panel 12 is primarily arranged on the front of the base unit door 7. Other alternative arrangements are also conceivable, e.g. on the front of the housing 1, divided up into different subpanels and/or partly on side surfaces of the cooking appliance. Further embodiments are possible. The design of the control elements 11 is not restricted and can for example include control knobs, rocker switches, pushbuttons and foil switches which include display elements 14, e.g. LED, LCD and/or touchscreen displays.

A front view of a high-level cooking appliance is shown schematically and not true-to-scale in FIG. 5, in which the base unit door 7 is open and in contact with the work surface 8. The closed state is shown by a dotted outline.

In this embodiment there are two movement control panels 25 on the front side of the permanently attached housing 1. Each movement control panel includes two press buttons, namely an upper CLOSE button 25a for a base unit door 7 moving upwards in the closing direction and a lower OPEN button 25b for a base unit door 7 moving downwards in the opening direction. With no automatic mode the base unit door 7 only moves upwards where possible with a continuous simultaneous pressure on the CLOSE buttons 25a of the two movement control panels 25; the base unit door 7 also only moves downwards, where possible, with a continuous simultaneous pressure on the OPEN buttons 25b of the two movement control panels (manual operation). Since in manual operation the user has to take greater care during operation and in addition both hands are used for this operation, anti-trap protection is then only optional. In an alternate embodiment the movement control panels 26 are accommodated on opposite outer sides of the housing 1 with the corresponding CLOSE buttons 26a and OPEN buttons 26b, as shown by the dotted outline.

The control circuit 13 indicated by a dashed outline, which is located inside the base unit door behind the control panel 1, switches the drive motor 9 so that the base unit door 7 starts to move smoothly, i.e. not abruptly by simply starting the drive motor 9, but by using a defined ramp.

The control circuit 13 in this exemplary embodiment includes a memory unit 27 for storing at least one target or movement position P0, PE, P1, P2, PZ of the base unit door 7, preferably with volatile memory chips, e.g. DRAMs. If a target position P0, P1, P2, PZ is stored, the base unit door can move after actuation of one of the buttons 25a, 25b or 26a, 26b on the movement control panels 25 or 26 in the direction set automatically until such time as the next target position is reached or one of the buttons 25a, 25b or 26a, 26b is actuated once more (automatic mode). In this exemplary embodiment the lowest target position PZ corresponds to the maximum opening, the (zero) position P0 to the closed state, and P1 and P2 to freely-selectable intermediate positions. Once the last target position for a direction has been reached in manual operation the door must be moved beyond this position if this is possible (meaning that the last end positions do not correspond to a maximum opened or the closed end state). In a similar manner, when no target position is stored for a direction—which for example would be the case for an upwards movement into the closed position, if only PZ is stored, but not P0, P1, P2—the door must be moved in this direction in manual mode. if no target position is stored, e.g. with a new installation or after a power disconnection, no automatic mode is possible. If the base unit door 7 is moved in automatic mode an anti-trap protection is preferably activated.

Automatic mode and manual mode are not mutually exclusive: Continuous pressure on the movement control panel or panels 25, 26 causes the base unit door 7 to move in manual operation even if a target position were able to be moved to in this direction. In this case for example a maximum actuation time of the movement control panels 25 or 25 or the associated buttons 26a, 26b or 26a, 26b respectively can be defined for activation of automatic mode, e.g. 0.4 seconds.

A target position P0, P1, P2, PZ can be any position of the base unit door 7 between and including the zero position P0 and the maximum opening position PZ. The maximum stored opening position PZ does not however have to be the position at which the door is resting on the work surface 8. The target position P0, P1, P2, PZ can be stored with the base unit door 7 at the desired target position P0, P1, P2, PZ, by for example actuating an actuation button 28 in the control panel 12 for a number seconds (e.g. a period of two seconds). Existing optical and/or acoustic signal generators which output appropriate signals after a target position has been stored are omitted from the diagram to improve its clarity. Moving the door to the desired target position P0, P1, P2, PZ to be set is undertaken for example by—in this exemplary embodiment—two-handed operation of the movement control panels 25 or 26 and manual movement to this position.

Just one, or as shown in this exemplary embodiment, a number of target positions P0, P1, P2, PZ, can be stored in the memory unit 27. With a number of target positions P0, P1, P2, PZ, these positions can be moved to in turn by actuating the corresponding movement buttons 25a, 25b or 26a, 26b. The number of target positions P0, P1, P2, PZ enables the high-level cooking appliance to be adapted conveniently to the desired operating height of a number of users. The target position(s) are advantageously able to be deleted and/or overwritten. In one embodiment for example only one target position is able to be stored in the open state whereas the zero position P0 is automatically detected and the door is able to be moved to this position automatically. Alternately the zero position P0 must be stored to enable the door to be moved there automatically.

It is especially advantageous for ergonomic use if the target positions or a target position P1, P2, PZ opens the base unit door 7 at least appr. 400 mm to appr. 540 mm (i.e. P1-P0, P2-P0, PZ-P0≧40 cm to 54 cm). With this opening dimension the food supports 21 can be easily placed into their holder elements 20. In this case it is useful for the viewing window to be mounted at about the eye level of the user or slightly below, e.g. using a template which indicates the dimensions of the cooking appliance.

Not shown in the drawing is an existing uninterruptible power supply for bridging a power failure of around 1 to 3 seconds, preferably of around 1.5 seconds.

The drive motor 9 from FIG. 1 has at least one sensor unit 31, 32 on a motor shaft 30, if nec. arranged in front of or behind a gear, in order to measure a movement path or a position and/or a speed of the base unit door 7. The sensor unit can for example also include one or more induction, Hall, opto, OFW sensors and so forth. In this case, for simple measurement of the distance and speed, two (part) Hall elements offset by 180°—i.e. opposite each other—are accommodated on the motor shaft 30, and a Hall measurement recorder 32 is fixed permanently at a distance in this area of the motor shaft. if a Hall element 31 then moves past the measurement recorder 32 as the motor shaft 30 rotates, a measurement or sensor signal is created which is a good approximation of a digital signal. With (not necessarily) two Hall elements, two signals are thus output for one rotation of the motor shaft 30. By evaluating the timing of the signals, e.g. their time difference, the speed vL of the base unit door 7 can be determined, for example using comparison tables or a conversion in real time in the control circuit 13. By addition or subtraction of the measurement signals a movement path or a position of the base unit door 7 can be determined.

A speed regulator can for example implement the speed via a PWM-controlled power semiconductor.

For determining the zero position the path measurement is automatically newly synchronized in the zero position P0 of the base unit door 7 for each movement to this position, so that for example an error in a sensor signal output or detection does not have any effect.

The drive motor 9 can be operated by actuating the two movement control panels 25 or 26 even with the main switch 29 switched off.

Instead of two separate switches per movement panel 25, 26, a single switch per movement panel is also possible, e.g. a rocker switch with a neutral position which only switches under pressure. Other forms are also possible. The type and arrangement of the control elements 28, 29 of the control panel 12 is also not restricted.

The arrangement and sub-division of the control circuit 13 in this case is flexible and not restricted, meaning that it can also consist of a number of circuit boards e.g. a display circuit board, a control circuit board and a lift circuit board which are in separate locations.

A 4 mm opening dimension for example can be detected by end switches 33, which on actuation deactivate an anti-trap protection. It is possible however for the anti-trap protection to be deactivated by counting pulses of the sensor signals when a count is reached, which corresponds to a closure dimension of 8.6 mm for example. The anti-trap protection is deactivated in this case independently of such end switches 33.

Alternately only anti-trap protection measures are deactivated that do not operate with threshold values, e.g. mechanical switches, especially anti-trap protection mechanisms not using a movement parameter of the door.

The high-level cooking appliance can also be embodied without a memory unit 27, with no automatic mode then being possible. This can be useful for increased operator safety, e.g. for anti-trap protection.

FIG. 6 shows a diagram, not drawn to scale of a graph of the speed of movement vL of the base unit door 7 in mm/s plotted against the position of the base unit door in mm from the zero position P0 for a movement of the base unit door 7 from the closed state with P0=0 mm to PZ=maximum opening of 530 mm in this case in manual movement mode (i.e. not moved automatically), as well as, indicated by the dotted-line arrow, the displacement movement being stopped between P0 and PZ. The curve is executed in the direction of the arrow, i.e. from right to left. The arrows pointing downwards above the curve indicate actuations of the control panel 12.

The downwards displacement movement of the base unit door 7 begins with two-handed activation of the movement switch panels 25, 26 or of the OPEN switches 25b or 26b, as indicated by the upper left vertical arrow. The control circuit 13 regulates the drive motor 9 so that the base unit door 7 is slowed smoothly, i.e. with a defined ramp R1, to its required speed of here vL=50 mm/s. The ramp R1 is linear here. The drive motor 9 is thus not simply switched on.

The drive displacement movement is also independent of the load, especially independent of the loading of the base unit door 7 or of changed frictional conditions of the mechanism. An input variable for this can be the speed of the drive motor 9 which can for example be measured by Hall sensors.

After reaching the required speed of vL=50 mm/s the base unit door 7 moves constantly downwards until it approaches the maximum opening PZ which is defined by the constructionally predetermined maximum movement of the base unit door 7 or by reaching the work surface 8. In this figure it is assumed that the maximum opening PZ dictated by the construction is reached. In this case the control circuit 13 detects this approach and brakes the base unit door 7 smoothly automatically, i.e. with a defined ramp R2, down to PZ. Both ramps R1 and R2 can have other slopes or shapes. The approach to the base plate can be detected by the end switch 33 and/or by monitoring the movement path.

If one or both of the movement switches 25b, 26b is released, as indicated by the upper vertical arrow, the base unit door 7 stops abruptly without any ramp, as indicated by the dotted-line arrow. Thus the door starts to move smoothly in this case but, —except where it reaches the end position—it is stopped abruptly.

The cooking compartment 3 is not opened, the base unit door 7 is thus not moved from the zero position P0, if an opening protection system is active, if for example a specific temperature in the cooking compartment e.g. 425° C. or 600° F., is exceeded or if a child lock is activated.

FIG. 7 shows a diagram similar to that depicted in FIG. 6, also not drawn to scale, for a movement of the base unit door 7 from the closed state to a stored position P1=476 mm in automatic movement mode.

In this case the base unit door 7 begins to move automatically to position P1 by brief activation of the OPEN switch 25b or. 26b, as indicated by the upper right-hand vertical arrow. In this case too the base unit door 7 is started up smoothly (right-hand ramp) and braked automatically (left-hand ramp). In this embodiment a choice can be made in automatic mode between two fixed setpoint speeds, namely 75 mm/s (dashed line) and 50 mm/s (solid line), with the slower speed being better for older users in particular. The lower speed level is preset ex-works for example. More than two speed levels or setpoint speeds can also be provided; A free choice of setpoint speed(s) by the user is also conceivable. Expediently it is also possible to switch at least between two speed levels of 50 mm/s and 65 mm/s, e.g. during appliance initialization.

FIG. 8 shows a diagram, not drawn to scale, for moving the bottom door 7 from the maximum opening position PZ to the zero position P0, i.e. in the closed state, in manual operation.

The upwards displacement movement of the base unit door 7 begins with two-handed activation of the CLOSE switches 25a or 26a, as indicated by the upper left vertical arrow. The control circuit 13 regulates the drive motor 9 so that the base unit door 7 is moved smoothly from PZ up to its setpoint speed of vL=50 mm/s, and then moved constantly at this setpoint speed (to the right).

The control circuit 13 detects an approach to the zero position P0 and brakes the door 7 smoothly in good time beforehand. Instead however of now moving downwards by means of the linear ramp directly to the zero position P0, 4 mm before the zero position P0 the speed-dependent control switches over to control with a defined voltage, i.e. by supplying the motor 9 with a corresponding voltage. This allows a maximum force developed during blocking of the drive motor 9 to be set. This voltage differs in accordance with the previous history of the movement (loading, friction conditions etc.). The 4 mm opening dimension is detected via the distance measurement or in addition or as an alternative via the end switches 33. Anti-trap protection can also be dispensed with in the area from P0 to P0+4 mm.

If, as in FIG. 6, one or both of the movement switches 25b, 26b is released, as indicated by the upper right-hand vertical arrow, the base unit door 7 stops abruptly without a ramp, as indicated by the dotted arrow.

FIG. 9 shows a diagram, not drawn to scale, for a movement of the base unit door 7 from a stored position P1=476 mm into the closed state P0 in automatic movement mode. By contrast with the manual movement mode shown in FIG. 8, only one of switches 25a, 26a now needs to be briefly actuated, as indicated by the upper horizontal arrow. The base unit door 7 then moves as in FIG. 7, but in the other direction. When it approaches the zero position P0, as with the situation from FIG. 8, the braking ramp switches for the last 4 mm opening from a speed-controlled state to a load or closing force-controlled state.

FIG. 10 shows a diagram similar to FIG. 8, in which trapping now occurs at a setpoint speed of vL=50 mm/s, as indicated by the upper vertical arrow. If an object, for example a hand or a pot etc., becomes trapped between the base unit door 7 and the housing 1, the speed of the base unit door 7 drops since the object is hindering further movement. The speed of lift is monitored here for example through evaluation of the sensor signals of the motor shaft, with the time between the measuring signals or impulses being evaluated for example. Only in the second instance is the motor current monitored, which is a somewhat slower method. In particular the force able to be exerted by the motor 9 for movement is restricted to avoid accidents caused by the object being trapped too tightly (see also FIGS. 12 and 13). The deviation from the setpoint speed is detected by the control circuit 13, e.g. through a variation in the speed or a change in the speed over time. The base unit door then reverses so that the object can be removed; an acoustic warning signal is also issued if necessary. Thereafter the base unit door 7 only starts to move again after the corresponding movement keypad 25, 26 is pressed again.

So that anti-trapping is not triggered incorrectly, by a changed loading for example or a change in the movement characteristics of the mechanism, the anti-trap protection may only be activated if the base unit door 7 has reached its setpoint speed (if a movement key 25a, 25b, 26a, 26b is released beforehand, the base unit door 7 comes to a halt immediately), and secondly a number of sensor signals may be evaluated, for example averaged.

FIG. 11 shows the operation of anti-trapping (upper vertical arrow) during an opening movement of the base unit door 7 in automatic mode to a target position P1, in which an object is trapped between the lower side of the base unit door 7 and the work surface 8. In this case detection of the trapped object can be undertaken via two redundant end switches, which detect an—especially uneven—relief of the load on the base unit door 7, at which point the drive motor 9 reverses. The maximum allowed force time profile (see FIGS. 12 and 13) is not exceeded in this case.

FIG. 12 shows a maximum force F in N able to be applied to the base unit door 7 in the event of trapping when the door is moving in a closing direction (i.e. upwards) plotted against the elapsed time t in s as a first force time profile FT1.

If trapping occurs when t=0 s the possible closing force is limited to 100 N, corresponding to appr. 10 kg, for 5 s. This is sensible for example if the motor 9 is regulated upwards by the control device 13 to maintain the required speed. This especially ensures that parts of the body will not be injured. If the base unit door is accelerated for 5 s with (maximum) 100 N, the maximum force applicable drops further to 25 N, e.g. for 5 seconds. Subsequently this force level can be maintained or reduced further to 0 N for example. It should be stressed that this force time profile FT1 only specifies the maximum applicable force, and the actually applied force generally lies below this, e.g. if the trapping is detected by the control device 13, and the base unit door 7 is reversed accordingly after t=0.5 s, after which the applied force of 100 N drops to 0 N for example.

The maximum force threshold value of 100 N can also apply for further movement situations.

FIG. 13 shows a maximum force F in N able to be applied to the base unit door 7 in the event of trapping when the door is moving in an opening direction (i.e. downwards) plotted against the elapsed time t in s as a second force time profile FT2. Here the drive motor 9 in a first block of t=[0 s; 0.5 s] can apply up to 400 N to the base unit door 7, then for t=[0.5 s; 5 s] 150 N and then 25 N.

Naturally the time intervals and force threshold values of the force time profiles FT1, FT2 are adapted to the structure and further peripheral conditions.

FIG. 14 shows a typical flowchart, in which a speed vL with which the door 7 is moved is plotted against a position P at a particular moment. The speeds specified in millimeters per second mm/s or the heights specified in millimeters are however to be seen purely as examples.

Starting from an end position PZ, at which the door 7 is stationary, the door 7 is accelerated by the drive motor 9 until it reaches a lower intermediate position P2 and/or a required speed vR. From the lower intermediate position P2, the door 7 is moved at a constant speed upwards until it reaches a further, upper intermediate position P1. As from this upper intermediate position P1 the speed is reduced until a zero position P0 is reached which corresponds to a closed state, so that a braking speed curve again assumes a ramp shape.

Optionally, while the door 7 is moving upwards, a method for monitoring a trapping state can be activated, with such a method especially in the case of pure speed monitoring on switchover to braking mode, i.e. especially from reaching the upper intermediate position P1, being deactivated in accordance with a typical embodiment. In accordance with another typical embodiment such monitoring of a trapping state is deactivated only after reaching a higher switchover position PS or is even not deactivated at all. The switchover position PS can for example be detected by the reaching of an end switch 33 or the detection of a predetermined approach state of the door 7 to the muffle 5 as a result of an accumulated number of Hall impulses.

In particular there can be provision for a switchover between a anti-trap protection monitoring mode and a closing mode to be undertaken, with for example the end switches 33 serving during the initial upwards movement of the door 7 for monitoring anti-trap protection while the same end switches 33 serve during the final approach of the door 7 to the muffle 5 for closure state monitoring in order to monitor a safe a firm closure of the door 7. With such a switchover in particular the switchover expediently occurs a little way before the zero position P0 is reached. In particular the switchover is undertaken appr. 4-10 mm before the zero position P0 is reached.

With such an approach of the door 7 to the muffle 5 or to a flange fitted to the lower side of the muffle, trapping of usual objects used in the household can be excluded. However there is the danger of a thin child's finger, a pin or similar still being able to penetrate into a narrow gap of this type, which could lead to the child's finger being squashed and seriously injured.

Preferably an additional or alternate method for monitoring a trapping state is activated, which however can also be activated during the remaining upwards movement sequence. In this method the cooking appliance is equipped with a functionality which detects a trapping state through a threshold value which depends on a displacement movement, especially a speed of the door 7.

The speed falling below a minimum (threshold value) vS and/or the increase in the duration of measuring signals of a Hall-element 31, i.e. a change in a differential speed, is preferably used as a threshold value here. However the monitoring of a motor current or of power drawn by the motor is accordingly also able to be used as a threshold value.

In the execution sequence shown the door 7 approaches the zero position P0 with the speed of a braking movement. As can be seen from the enlarged section of FIG. 14, in the last closing section shortly before the zero position P0 is reached, an object gets between the door 7 and the muffle 5 and causes an increasing speed reduction, which is shown as a reducing trapping speed curve.

By contrast with a hard body, a partly elastic body such as especially a child's finger does not cause an abrupt stop reducing the speed to a value of zero when it becomes trapped, but initially only a reduced slowdown in the speed. The undershooting of the minimum speed vS, which is predefined for this section and/or the increase in the differential speed ΔvS or duration of measurement pulses of the Hall elements 31 which are predefined for this section can be detected as a criterion.

After the detection of a trapping state the speed of the door 7 is preferably reduced to zero and subsequently briefly increased in the opposite direction. During a reset speed curve v2 depicted and a subsequent renewed braking speed curve v3, the door 7 is preferably moved a little away from the muffle 5 by an opening distance s, so that the trapped object can be removed.

Preferably a measuring signal of Hall element is used for such monitoring of the trapping state in the remaining opening distance s, which monitors a rotation of a drive shaft between the drive motor 9 and a lifting element 10 for raising the door 7. However other signal receivers can also be used which monitor an instantaneous distance of the door 7 from the muffle 5 directly by means of optical or mechanical movement sensors, speed sensors or acceleration sensors. A changing motor output, meaning a power consumption of the drive motor 9, can also be included as a measuring signal.

As well as the use of such a method of operation for monitoring the movement of the door 7 during a final closure operation, such a method can basically be used over the entire movement path. Also especially possible is the use of such a method in addition to the use of further methods for monitoring a trapping state, if necessary also further methods based on hardware, i.e. switches in particular.

LIST OF REFERENCE SYMBOLS

• 1 Housing
• 2 Wall
• 3 Cooking compartment
• 4 Viewing window
• 5 Muffle
• 6 Muffle opening
• 7 Base unit door
• 8 Work surface
• 9 Drive motor
• 10 Lifting element
• 11 Control element
• 12 Control panel
• 13 Control circuit
• 14 Display elements
• 15 Cooking zone
• 16 Hotplate heating elements
• 17 Hotplate heating elements
• 18 Radiant heating elements
• 19 Glass ceramic plate
• 20 Holder part
• 21 Food carrier
• 22 Overhead heating element
• 23 Fan
• 24 Seal
• 25 Movement control panel
• 25a Upwards movement switch
• 25b Downwards movement switch
• 26 Movement control panel
• 26a Upwards movement switch
• 26b Downwards movement switch
• 27 Memory unit
• 28 Actuation button
• 29 Main switch
• 30 Motor shaft
• 31 Hall element
• 32 Measuring sensor
• 33 End switch
• FT1 First force time profile
• FT2 Second force time profile
• P0 Zero position
• P1 Intermediate position
• P2 Intermediate position
• PZ End position
• PS Switchover position
• R1 Speed ramp
• R2 Speed ramp
• vL Speed of movement of the base unit door
• vR Setpoint speed
• vS Threshold speed
• v Permitted minimum speed
• Δv Differential speed
• v2 Reset speed curve
• v3 Braking speed curve
• s Opening path

Claims

1-38. (canceled)

39. A cooking appliance including a high-level cooking appliance having a muffle including a muffle compartment defining a cooking compartment with a muffle opening, a door for movement between an open and closed relationship with the muffle opening and a drive device controlled by a control device for moving the door, the cooking appliance comprising a detector for determining a trapping condition wherein an object becomes trapped as the door is being moved, wherein the detector is configured for detecting the trapping state by comparing a door movement parameter with a threshold value associated with door movement.

40. The cooking appliance according to claim 39 wherein the door movement parameter corresponds to a speed of movement of the door and the threshold value corresponds to a permitted minimum speed.

41. The cooking appliance according to claim 39 wherein the door movement parameter corresponds to door acceleration and the threshold value corresponds to a permitted minimum door acceleration.

42. The cooking appliance according to claim 39 wherein the monitoring of the trapping state dependent on the threshold value is activated within a predetermined movement path of the door.

43. The cooking appliance according to claim 42 wherein the movement path of the door includes a zero position corresponding to a closed position of the door.

44. The cooking appliance according to claim 39 wherein monitoring of the trapping state is activated within the last movement path of the door before a zero position corresponding to a closed position of the door is reached.

45. The cooking appliance according to claim 39 wherein monitoring of the trapping state is activated within the last 15 mm, especially the last 10 mm, especially the last 5 mm movement path of the door before a zero position corresponding to a closed position of the door is reached.

46. The cooking appliance according to claim 39 wherein monitoring of the trapping state dependent on the threshold value is activated after a switchover from a different trapping state monitoring method.

47. The cooking appliance according to claim 39 and further comprising an end switch in operational association with the door wherein monitoring of the trapping state dependent on the threshold value is activated after activation of the end switch.

48. The cooking appliance according to claim 39 wherein monitoring of the trapping state dependent on the threshold value is activated during a switchover to a force-regulated closure movement of the door.

49. The cooking appliance according to claim 39 and further comprising a speed measurement device for measuring a speed of door movement.

50. The cooking appliance according to claim 39 and further comprising a speed measurement device for measuring a speed of door movement wherein an uncontrolled reduction in the speed of door movement is indicative of an object becoming trapped in the door.

51. The cooking appliance according to claim 39 and further comprising a speed measurement device for measuring a speed of door movement wherein a deviation from a setpoint speed of door movement is indicative of an object becoming trapped in the door.

52. The cooking appliance according to claim 50 wherein the monitoring of the speed of door movement includes monitoring door acceleration.

53. The cooking appliance according to claim 39 wherein the speed measuring device includes at least one sensor operationally disposed on a motor shaft of the drive device for generating signals corresponding to rotation of the motor shaft.

54. The cooking appliance according to claim 53 wherein the at least one sensor is formed as a Hall sensor configured for generating two sensor signals for each rotation of the motor shaft.

55. The cooking appliance according to claim 53 wherein the speed of door movement determined by a time difference between the sensor signals.

56. The cooking appliance according to one of the claims 53 and further comprising means for evaluating and averaging a plurality of sensor signals.

57. The cooking appliance according to claim 39 and further comprising means for reversing a direction of door movement when an object becomes trapped in the door.

58. The cooking appliance according to claim 39 and further comprising means for controlling the direction of displacement movement of the door as a function of the door speed.

59. The cooking appliance according to claim 58 wherein anti-trap protection is only activated when the setpoint speed of the door is reached.

60. The cooking appliance according to claim 39 and further comprising means for preventing a predetermined door driving force from being exceeded when an object becomes trapped in the door.

61. The cooking appliance according to claim 39 and further comprising at least one end switch operationally disposed in an area between the muffle opening and door and that an actuation of the at least one end switch deactivates an anti-trap protection device.

62. The cooking appliance according to claim 61 wherein the at least one end switch is able to be actuated within an opening dimension of about 4 mm between the muffle opening and the door.

63. The cooking appliance according to one of the claims 61 and further comprising means for moving the door with a predetermined force toward the muffle opening upon actuation of the at least one end switch.

64. The cooking appliance according to claim 39 and further comprising a high-level cooking appliance wherein the muffle opening is formed with a downwardly directed muffle opening and the door is formed as a base unit door.

65. A method for operating a cooking appliance including a high-level cooking appliance having a muffle including a muffle compartment defining a cooking compartment with a muffle opening, a door for movement between an open and closed relationship with the muffle opening and a drive device controlled by a control device for moving the door, the method comprising the steps of providing a detector for determining a trapping condition wherein an object becomes trapped as the door is being moved, and detecting an object trapped in the door by a comparison of a door movement parameter with a threshold value associated with door movement.

66. The method according to claim 65 wherein the threshold value is based on a permitted minimum speed.

67. The method according to claim 65 wherein the threshold value is based on a differential speed.

68. The method according to claim 65 and further comprising the step of activating monitoring of the trapping state within a predetermined movement path of the door.

69. The method according to claim 68 and further comprising the step of defining the movement path of the door before a zero position of a closed door corresponding to a closed position.

70. The method according to claim 65 and further comprising the step of activating monitoring a trapping state within the last movement path of the door before it reaches a zero position corresponding to a closed position.

71. The method according to claim 69 and further comprising the step of activating monitoring of a trapping state within the last 15 mm, especially 10 mm, especially 5 mm movement path of the door before it reaches the zero position.

72. The method according to claim 65 and further comprising the step of activating monitoring of the trapping state dependent on the threshold value in conjunction with or after a switching off a different anti-trap protection method.

73. The method according to claim 65 and further comprising the step of activating monitoring of the trapping state dependent on the threshold value in conjunction with or after an activation of an end switch.

74. The method according to claim 65 and further comprising the step of activating monitoring of the trapping state dependent on the threshold value during a switchover to a force-regulated closing movement of the door.

75. The method according to claim 65 and further comprising the step of reversing a direction of door movement in the event of a trapping situation.

76. The method according to claim 65 wherein the step of detecting a speed of door movement results in detecting door speed reduced in an uncontrolled manner a trapping situation is indicated.