Conveyor dishwasher equipped with an overload shut-off unit

Abstract

A dishwasher having a conveyor device determines an estimated value for a deformation force of the conveyor device on one or more racks or on a conveyor belt on the basis of a motor current determined by a current determination unit, a movement speed of the one or more racks or of the conveyor belt, a movement acceleration of the one or more racks or of the conveyor belt and one or more conveyor device parameters. The dishwasher switches off a motor of the conveyor device if the estimated value meets a threshold value condition which is based on one or more dishwasher parameters.

Description

[0001] TRANSPORT DISHWASHER EQUIPPED WITH AN OVERLOAD SHUT-OFF UNIT

[0002] Description

[0003] The present invention relates to a dishwasher with a transport device.

[0004] Overload protection devices are commonly used in conveyor dishwashers with belts or baskets. These devices include, for example, mechanical slip clutches, safety clutches, or torque shear sensors that work against a spring. However, a disadvantage of these devices is the need for wear-prone mechanical components, and the fact that the overload protection devices trigger under the same load throughout the entire application. Furthermore, the manufacture of such systems is expensive.

[0005] It is an object of the present invention to provide a dishwasher with a transport device in order to improve user-friendliness with regard to the desired applications.

[0006] The above problem is solved by a dishwasher according to claim i. Claims 2 to 17 relate to particularly advantageous implementations of the dishwasher according to claim 1.

[0007] The present invention relates to a dishwasher comprising a transport device and a current control unit.

[0008] The transport device comprises a transport element, a motor, and an inverter. The transport element is configured to move one or more dish baskets along a transport direction or to move a transport belt, conveyor belt, or conveyor belt for dishes in a circular direction. The transport element may include, for example, one or more drive rollers, a gearbox, and / or other mechanical components. In particular, the transport element may be configured to move the one or more baskets relative to a frame or housing of the dishwasher or relative to a component that is fixed to the frame or housing. The motor is configured to drive the transport element.The motor can, in particular, transmit torque to the conveying element, causing the conveying element to exert a force on the one or more baskets or the conveyor belt, thereby moving the baskets along the conveying direction or moving the conveyor belt in the direction of rotation. The inverter is configured to convert an input voltage or mains voltage into an output voltage and supply the output voltage to the motor.

[0009] The current determination unit is configured to determine the motor current. The current determination unit may, in particular, include a current sensor or be a current sensor configured to detect or measure the motor current. The motor current may, in particular, be a Q-current of the motor (i.e., a current along the Q-axis (squaring axis), or a torque-generating current obtained from the Park transformation of the currents through the motor phases).

[0010] The dishwasher, or a control unit of the dishwasher, is configured to determine an estimated value for the deformation force of the transport device or element on the one or more baskets or on the conveyor belt. This estimate is based on the motor current determined by the current-determining unit, the speed of movement or conveying speed of the one or more baskets along the transport direction or the speed of movement of the conveyor belt in the direction of rotation, the acceleration of movement of the one or more baskets along the transport direction or the acceleration of movement of the conveyor belt in the direction of rotation, and one or more transport device parameters. The control can be implemented using software and / or hardware components. This estimated value is also referred to as the power score.The deformation force can, in particular, be a force acting on the one or more baskets or the conveyor belt, directed in the direction of transport. The deformation force can be a component of the total force exerted by the transport device or element on the one or more baskets or the conveyor belt. The total force can be the sum of the deformation force and an acceleration force used to accelerate the one or more baskets along the direction of transport or the conveyor belt in the direction of rotation. The deformation force can oppose a blocking force or a frictional force, in particular a static or kinetic friction force, which acts on the one or more baskets or the conveyor belt in the event of a blockage or disturbance of their movement.The speed of movement of the one or more baskets along the transport direction or of the transport belt in the direction of rotation can, in particular, correspond to a motor speed, increase with the motor speed, or be proportional to the motor speed. The motor speed can correspond to the inverter output voltage, increase with the inverter output voltage, or be proportional to the inverter output voltage. The acceleration of movement can be determined by a relationship between the speed of movement and a target speed for the movement of the one or more baskets along the transport direction or of the transport belt in the direction of rotation, as described in more detail below. The one or more transport device parameters can be specific to the respective transport device and, in particular, depend on the type of transport device (e.g.,The dishwasher can be configured to determine the estimated value as a function of time or a time variable. This estimated value, at any given time, can be based on the motor current determined by the current measuring unit at that time, the movement speed at that time, the movement acceleration at that time, and one or more transport device parameters. These one or more transport device parameters can be independent of time.

[0011] The dishwasher, or its controller or control unit, is configured to switch off the motor or reduce the inverter output voltage when a threshold condition, based on one or more dishwasher parameters, is met. The dishwasher can switch off the motor by setting the inverter output voltage to zero.The threshold condition is met if: the estimated value or the amount of the estimated value exceeds or has exceeded for a first period of time a first threshold based on the one or more dishwasher parameters (level-based overload detection) and / or a temporal increase or the amount of a temporal increase of the estimated value or the amount of the estimated value exceeds or has exceeded for a second period of time a second threshold based on the one or more dishwasher parameters (gradient-based overload detection).

[0012] The dishwasher according to the invention has the advantage that switching off the motor or reducing the output voltage of the inverter is not based on a mechanical force or torque measurement, but on an estimate of the deformation force based, among other things, on the motor current determined by the current measuring unit. This allows for a reduction in wear-prone mechanical components and results in a more robust machine with a longer service life. Furthermore, manufacturing costs can be reduced.

[0013] Furthermore, in the dishwasher according to the invention, the motor is not switched off or the output voltage of the inverter is reduced, as in conventional dishwashers, at a constant load, but rather adapted to the relevant parameters, in particular the movement speed, the movement acceleration, the one or more transport device parameters, and the one or more dishwasher parameters. The threshold condition, and thus the switch-off point, can be set specifically for the customer. Therefore, a variable switch-off point for the motor can be defined during operation, depending on these parameters. In particular, the transport device parameters are used, which can depend on the specific transport device. Moreover, the switch-off thresholds can be adapted to the specific machine, since the base load depends on the length of the machine, which in turn determines the maximum load and adhesion.Sliding friction is determined, which must not yet lead to a shutdown. Furthermore, transient effects are taken into account, in particular the acceleration of the transport system from standstill. Since static friction must be overcome, different parameters apply at this point for determining the estimated value than during uniform motion. Thus, the motor shutdown or the reduction of the inverter's output voltage can be carried out variably and early to avoid or minimize consequential damage to the dishwasher, the transport device, the baskets or conveyor belt, or the dishes. This also prevents injury to a user if, for example, a part of the user's body comes into contact with the transport device.The dishwasher can be switched off in time before excessive force is exerted on the body part, thus preventing injury to the user. Furthermore, this allows for a larger motor without risking damage from blockages, making the dishwasher more efficient and powerful.

[0014] Furthermore, the advantages described above can also be achieved in the case of technically inherent limitations of the transport device, particularly if torque control cannot be implemented by the transport device, for example, due to existing software components that do not include torque control. In this case, however, the software component used can provide access to internal variables or parameters that, as described above, allow indirect inferences to be drawn about the force of the transport system. The estimated value or power score then exhibits a sufficient correlation to the force in the transport direction to enable a threshold-based shutdown mechanism as described above.

[0015] If the dishwasher shuts off the motor when the threshold condition is met, this has the advantage of reliably preventing damage to the motor or other components of the dishwasher or the dishes. For example, in this case, a signal can be sent to the user indicating that the blockage must be cleared before the dishwasher can continue operating.If the dishwasher reduces the inverter's output voltage when the threshold condition is met, this has the advantage that reducing the inverter's output voltage decreases the motor speed and thus the force acting on the one or more baskets or the conveyor belt. This allows the dishwasher to continue operating even in the event of a malfunction without the force on the baskets or conveyor belt becoming excessive, thus preventing damage to the motor or other components of the dishwasher or the dishes. Furthermore, the use of the first and second time periods in the threshold condition has a filtering function: this compensates for noise and short overload spikes that may occur due to malfunctions.

[0016] In summary, the dishwasher according to the invention increases robustness and efficiency as well as user-friendliness and safety, and reduces manufacturing costs.

[0017] In a preferred embodiment, the dishwasher further comprises a voltage determination unit for determining the input voltage of the inverter, and the estimated value for the deformation force is further based on the input voltage of the inverter determined by the voltage determination unit.

[0018] This allows undesirable voltage fluctuations to be taken into account when determining the estimated value. Furthermore, the dishwasher according to the invention can be operated with different mains voltages, for example, in different countries with varying mains voltage standards. This increases user-friendliness.

[0019] In particular, the dishwasher can be calibrated to determine one or more transport device parameters. For example, a force sensor can be used to measure the deformation force exerted by the transport element on a test specimen during a calibration procedure. Simultaneously, the motor current during the calibration procedure, optionally the input voltage of the inverter during the calibration procedure, the speed of the test specimen's movement along the transport direction, and the acceleration of the test specimen's movement by the transport element can be determined. The transport device parameters can then be adjusted or optimized so that the estimated value for the deformation force corresponds to the measured deformation force. The process variables used to calculate the force value can be recorded electronically.Playing through different load scenarios (transport speed, voltage, loads from items being washed, etc.) allows the Q-current to be mapped sufficiently accurately onto the curve of the force sensor through translation and scaling.

[0020] In particular, the estimated value or the magnitude of the estimated value can be greater the greater the magnitude of the motor current. Additionally or alternatively, the estimated value or the magnitude of the estimated value can be greater the greater the input voltage or a certain magnitude or amplitude of the input voltage. Additionally or alternatively, the estimated value or the magnitude of the estimated value can be greater the greater the speed of movement of the one or more baskets along the transport direction or of the transport belt in the direction of rotation. Additionally or alternatively, the estimated value or the magnitude of the estimated value can be smaller the greater (given otherwise identical parameters, in particular identical motor current, identical input voltage, and identical speed of movement) the acceleration of movement of the one or more baskets along the transport direction or of the transport belt in the direction of rotation.The estimated value may depend in particular on an acceleration state, for example on whether the one or more baskets or the transport belt are accelerated, moved uniformly or decelerated by the transport device or are stationary, as described below.

[0021] This allows the deformation force of the transport device on the one or more baskets or on the transport belt to be estimated with exceptional precision, further enhancing user-friendliness. These advantages stem primarily from the fact that the motor current already contains the required information about the torque or deformation force, but is influenced by the motor's rotational speed (corresponding to the speed of movement of the one or more baskets or the transport belt), the inverter's input voltage, and the acceleration of the movement. These factors can thus be interpreted as "disturbing factors" that are suppressed by the modeling described above, enabling the precise and efficient shutdown described above.In particular, as described above, the total force exerted by the transport device or element on the one or more baskets or the transport belt can be the sum of the deformation force and an acceleration force used to accelerate the one or more baskets along the transport direction or the transport belt in the direction of rotation. The acceleration force must therefore be subtracted from the total force to obtain a precise estimate of the deformation force. Only an excessively high value of the deformation force should cause the motor to shut down. Therefore, it is advantageous that the estimated value of the deformation force is smaller the greater (all other parameters being equal) the acceleration of the motion of the one or more baskets along the transport direction or of the transport belt in the direction of rotation.

[0022] The one or more dishwasher parameters can include one or more of the following: a dishwasher type; a number of baskets or a conveyor belt length; an actual dishwasher load weight (in particular, a current load weight in a wash cycle, i.e., the weight of the load of items to be washed or dishes arranged in the one or more transport baskets or on the conveyor belt and cleaned in the wash cycle) or an average load weight (load weight in an average wash cycle, which can be preset by the customer or entered by the user, e.g.,(lower average load weight when using the dishwasher to wash light plastic cups and higher average load weight when using the dishwasher to wash heavy porcelain) or a maximum load weight (a maximum permissible load weight); and a duration or number of dishwasher cycles since the dishwasher was first put into operation.

[0023] In particular, the first threshold and / or the second threshold can be higher the greater the number of baskets or the length of the conveyor belt and / or the greater the average or maximum load weight of the dishwasher. This has the advantage that, in dishwashers with a larger number of baskets or a longer conveyor belt and / or a higher average or maximum load, even during trouble-free operation, greater forces act on the one or more baskets or the conveyor belt in the direction of transport. Therefore, a shutdown due to a blockage or malfunction may only occur at a higher threshold value, ensuring continuous and safe operation of the dishwasher and thus increasing user-friendliness.Furthermore, the dishwasher can include a load determination unit to determine the actual load weight, and the first and / or second threshold values ​​can be higher the greater the actual load weight determined by the load determination unit. This has the advantage that with a higher actual load weight, even during trouble-free operation, greater forces act on the one or more baskets or the conveyor belt in the transport direction, so that a shutdown due to a blockage or malfunction may only occur at a higher threshold value to ensure continuous and safe operation of the dishwasher.

[0024] Furthermore, the dishwasher can include an operating time determination unit to determine the duration or number of wash cycles since its initial commissioning. The first and / or second threshold values ​​can be higher the greater the duration or number of wash cycles determined by the operating time determination unit. This has the advantage that, for dishwashers that have been in operation for a longer period or have already completed a higher number of wash cycles, greater forces, especially frictional forces, act on one or more baskets or the conveyor belt in the transport direction, even during trouble-free operation, for example, due to increased wear. Therefore, a shutdown due to a blockage or malfunction may only occur at a higher threshold value to ensure continuous and safe operation of the dishwasher.

[0025] In a preferred embodiment, when the threshold condition is met, the dishwasher is configured to switch off the motor, and the transport device or element is configured to move the one or more baskets back in a direction opposite to the direction of transport, in particular by a predetermined transport distance, or to move the transport belt back in a direction opposite to the direction of rotation, in particular by a predetermined rotation distance. By moving back, the deformation force on the one or more baskets or the transport belt is reduced or eliminated in the event of a blockage, thus preventing damage to the one or more baskets or the transport belt or other components of the dishwasher or the dishes, and thereby increasing user-friendliness.

[0026] The estimated value for the deformation force can, in particular, be based on an RMS current, where the RMS current is the sum of the motor current and a correction current, the correction current depending linearly on the input voltage of the inverter. In particular, the RMS current (I) e ff) in the following relationship to the motor current (I q ), the input voltage (Um) of the inverter, a zero transport device parameter (Co) and a first transport device parameter (Ci):

[0027] (1) Ieff = Iq + Co + Ci * Uin •

[0028] Furthermore, the estimate can depend linearly on the motor current or the RMS current. The estimate can also depend linearly on the movement speed. In particular, one, more, or all of the following relationships i) to iv) can be satisfied: i) If the movement of the one or more baskets along the transport direction or the movement of the conveyor belt in the direction of rotation is uniform or consistent, or if the movement speed is constant (especially if the target movement speed is equal to the (actual, current) movement speed or lies within a narrow range around the (actual, current) movement speed, e.g., corresponding to a difference in motor speed of a maximum of ± 20 rpm), the estimate can be a uniformity estimate (P). un i) be, which is in the following relationship to the effective flow (I eff), the speed of movement (v), a second transport device parameter (C2), a third transport device parameter (C3) and an eighth transport device parameter (Cs):

[0029] (2) Puni = C2 + C3 * Ieff + C8 * V . ii) If the movement of the one or more baskets along the transport direction or the movement of the transport belt in the direction of rotation is accelerated (especially if the target speed of the movement is higher or significantly higher than the (actual, current) movement speed, e.g. corresponding to a motor speed at least 20 rpm higher), the estimate can be an acceleration estimate (P acc ) which is in the following relationship to the effective flow (I e ff), the speed of movement (v), a fourth transport device parameter (C4), a fifth transport device parameter (C5) and a ninth transport device parameter (C9):

[0030] (3) Pace = C4 + C5 * Ieff + C9 * V . iii) If the movement of the one or more baskets along the transport direction or the movement of the transport belt in the direction of rotation is delayed (especially if the target speed of the movement is lower or significantly lower than the (actual, current) movement speed, e.g. corresponding to a motor speed at least 20 rpm lower), the estimate can be a delay estimate (Pdec) which is related to the effective current (I) as follows: e ff), the speed of movement (v), a sixth transport device parameter (Ce), a seventh transport device parameter (C7) and a tenth transport device parameter (C10):

[0031] (4) Pdec = C6 + C7 * Ieff + Cio * V . iv) If the speed of motion is zero or small (e.g. corresponding to a motor speed of at most ± 20 rpm), the estimate can be a standstill estimate (Pstiii), where the standstill estimate (Pstiii) is equal to or essentially equal to zero:

[0032] (5) Pstiii = o .

[0033] The above calculations of the effective current and the estimated value, particularly under the various acceleration conditions, offer the advantage of a highly precise estimate of the deformation force exerted by the transport device on the one or more baskets or the conveyor belt, thus further enhancing user-friendliness. If, as described above, the movement speed, the inverter input voltage, and the acceleration are interpreted as "disturbance factors" of the motor current, which in itself already contains the required information about the torque or deformation force, these "disturbance factors" are suppressed particularly efficiently by the linear modeling described above, enabling the precise and efficient shutdown described above. Furthermore, the linear calculation of the estimated value reduces the computational effort (especially the numerical effort) and therefore the cost of the dishwasher.

[0034] Note that alternatively, in equations (2) to (5) the motor current (I) can also be used. q ) can be used instead of the effective current (Ieff). This further simplifies the above calculation and is particularly useful when the input voltage is constant or known in advance and does not need to be determined by the dishwasher.

[0035] These and other features and advantages of the invention will become clear with reference to the accompanying drawings, which show particularly advantageous embodiments. They show:

[0036] Fig. 1 shows an operating mode of a dishwasher according to an embodiment of the present invention; Fig. 2 shows an operating mode of a dishwasher according to an embodiment of the present invention with a level-based overload detection;

[0037] Fig. 2ß shows a mode of operation of a dishwasher according to an embodiment of the present invention with gradient-based overload detection;

[0038] Fig. 3 shows a mode of operation of a dishwasher according to an embodiment of the present invention with level- and gradient-based overload detection.

[0039] Fig. i shows an operating mode of a dishwasher according to an embodiment of the present invention. The dishwasher comprises a transport device, a current determination unit, a voltage determination unit, and a control unit io. The transport device comprises a transport element for moving one or more baskets for dishes along a transport direction or for moving a transport belt for dishes in a circular direction; a motor for driving the transport element; and an inverter configured to convert an input voltage into an output voltage and supply the output voltage to the motor. The current determination unit is configured to measure a motor current (I q) of the motor. The voltage determination unit is configured to determine the input voltage of the inverter (i.e., the mains voltage). The controller io is configured to determine an estimated value (P) for a deformation force of the transport device on the one or more baskets or on the transport belt based on the motor current determined by the current determination unit, the input voltage of the inverter determined by the voltage determination unit, a speed of movement of the one or more baskets along the transport direction or of the transport belt in the direction of rotation, a speed of movement of the one or more baskets along the transport direction or of the transport belt in the direction of rotation, and one or more transport device parameters. The controller io is further configured to switch off the motor (“STOP” in Fig. 1).i) when or as soon as a threshold condition based on one or more dishwasher parameters is met. In this embodiment, the threshold condition is met when: the estimated value exceeds (P > Pi) a first threshold (Pi) based on the one or more dishwasher parameters, or has exceeded it for a first time period, and a time-based increase (dP / dt) of the estimated value exceeds (dP / dt > P2) a second threshold (P2) based on the one or more dishwasher parameters, or has exceeded it for a second time period. The threshold condition is therefore "P > P" in this case. xand dP / dt > P2”, as shown in Fig. i, so that this dishwasher implements level- and gradient-based overload detection. Note that the threshold condition can alternatively be “P > Pi” (level-based overload detection only) or “dP / dt > P2” (gradient-based overload detection only). The controller 10 is further configured so that it does not switch off the motor (“GO” in Fig. 1) if the threshold condition is not met (P < Pi or dP / dt < P2). The transport device can also be configured to move the one or more baskets back along a direction opposite to the transport direction or to move the transport belt back in a direction opposite to the direction of travel (“BACK” in Fig. 1).Particularly in the case of a conveyor dishwasher with a drive belt, the belt can thus be moved back by a defined area immediately after the detected blockage, without operator input, in order to release the built-up tension.

[0040] In other words, the drive's power consumption is evaluated using a Q-current model-based estimate, or power score. To generate the power score, a model is used for four different states in which the speed-controlled drive system can be: acceleration, steady-state motion, deceleration, and standstill. Acceleration is defined as a target absolute velocity being higher than the actual absolute velocity. Deceleration is defined as a target absolute velocity being lower than the actual absolute velocity. Steady-state motion is defined as a target velocity being within a narrow range around the actual velocity (± 20 rpm). Standstill is defined as both the target velocity and the actual velocity being zero.A change in the direction of rotation is given special consideration and is treated as a deceleration to 0 rpm and as an acceleration to the new target speed in the opposite direction. Formulas (1) to (5), as stated above, describe the model. The power score is a piecewise defined function that selects the output of (2), (3), (4), or (5) depending on the current state of the drive system. The vector of transport device parameters Ci (i=0, 1, ..., 10) is available to the frequency converter via a CAN interface.

[0041] The following elements are included in the controller 10, in particular the control software: Current consumption (I q) and calculation of the estimated value P for the deformation force. The estimated value P, or rather its rate of increase over time, is monitored by the logic outlined in Fig. 1. The machine's control software or the frequency converter compares P with the first threshold value Pi specified in the software, or compares dP / dt with the second threshold value P2 specified in the software. If these two maximum values ​​are exceeded, the control system triggers the belt to stop ("STOP"). Optionally, the belt retraces a defined distance ("BACK"). If the displayed error message is acknowledged ("ATTERED"), the motor can restart. Alternatively, the software only triggers the system if P or dP / dt has been exceeded for a defined period. These threshold values ​​can be varied during the dishwasher's calibration or by a user.This allows, in particular, the machine length and a shift in the maximum threshold value over the machine's lifetime to be compensated for.

[0042] Fig. 2A shows the operation of a dishwasher according to an embodiment of the present invention with level-based overload detection. Fig. 2B shows the operation of a dishwasher according to an embodiment of the present invention with gradient-based overload detection. That is, in Fig. 2A and Fig. 2B, possible shutdown behaviors are illustrated based on the current consumption or the measured slope of the current consumption. In particular, Fig. 2A and Fig. 2B each show the time course of the inventive estimate for the deformation force or power score (P) when a blockage occurs. The power score is, in particular, a dimensionless quantity. In Fig. 2A, the threshold condition is met when the estimate exceeds the first threshold (the time of exceedance is indicated in Fig. 2A by "P = Pi") or has exceeded it for a first period of time (level-based overload detection). In Fig.2ß The threshold condition is met if a temporal increase in the estimated value exceeds the second threshold (the time of exceedance is indicated in Fig. 2A by "dP / dt = P2") or has exceeded it for a second period of time (gradient-based overload detection). In both cases, the motor is switched off after the blockage to prevent consequential damage.

[0043] The independent detection mechanisms shown in Fig. 2E and Fig. 2B can also combine to form the overload detection scheme used by the frequency converter (as already shown in Fig. 1): Only if both detection mechanisms detect a fault condition is the overload fault condition recognized and the corresponding fault set. This is also illustrated in connection with Fig. 3.

[0044] Fig. 3 shows the operation of a dishwasher according to an embodiment of the present invention with level- and gradient-based overload detection. In particular, Fig. 3 shows the time course of the power score (P) when a blockage occurs. The parameters shown in Fig. 3 are defined as follows: I_upper_limit: A current threshold value which, when exceeded, sets an internal error signal indicating that the power score is critical.

[0045] I_lower_limit: If the power score was critical, the corresponding error signal is cleared when the power score falls below this threshold. This threshold is lower than I_upper_limit. power_limit_delay: The time period for which the power score level must have been critical for the frequency converter to detect an overload condition based on the level. dl_gradient_limit: A difference in the power score rating that, if exceeded within a time frame of dt_gradient, triggers the detection of an overload condition based on the gradient of the power score rating. dt_gradient: The time frame for dl_gradient_limit. A dt_gradient of zero disables gradient observation. gradient_exceed_hold: The time period the frequency converter observes whether the gradient limit has been exceeded. If the gradient is exceeded again during the hold time, the observation period is extended.

[0046] As shown in Fig. 3, after a blockage occurs, the condition dP / dt > P2 is first met ("dl_gradient_limit"). After the time period "dt_gradient", during which this condition is continuously met ("gradient_limit_exceeded"), the time period "gradient_exceed_hold" begins. Within this time period, the condition P > Pi is also met ("power_limit_exceeded"). After the time period "power_limit_delay", during which the latter condition is continuously met, the motor is therefore switched off ("overpower_error_detected"). The software thus stops the drive because a blockage was detected based on the rapid increase in current consumption.

[0047] List of reference symbols

[0048] 10 Control

Claims

Claims 1. Dishwasher comprising: a transport device, the transport device comprising: a transport element for moving one or more baskets for dishes along a transport direction or for moving a transport belt for dishes in a circular direction; a motor for driving the transport element; and an inverter configured to convert an input voltage into an output voltage and supply the output voltage to the motor; and a current determination unit configured to determine a motor current of the motor;wherein the dishwasher is configured to determine an estimated value for a deformation force of the conveying device on the one or more baskets or on the conveying belt based on the motor current determined by the current determining unit, a speed of movement of the one or more baskets along the conveying direction or of the conveying belt in the direction of rotation, an acceleration of movement of the one or more baskets along the conveying direction or of the conveying belt in the direction of rotation, and one or more conveying device parameters; and wherein the dishwasher is configured to switch off the motor or reduce the output voltage of the inverter when a threshold condition based on one or more dishwasher parameters is met;where the threshold condition is met if: the estimated value or the amount of the estimated value exceeds or has exceeded for an initial period of time a first threshold based on the one or more dishwasher parameters and / or a temporal increase or the amount of a temporal increase of the estimated value or the amount of the estimated value exceeds a second threshold based on the one or more dishwasher parameters; based on, exceeds, or has exceeded several dishwasher parameters for a second period of time.

2. Dishwasher according to claim 1, which further comprises a voltage determination unit for determining the input voltage of the inverter; and wherein the estimated value is further based on the input voltage of the inverter determined by the voltage determination unit.

3. Dishwasher according to claim 1 or 2, wherein the estimated value or the amount of the estimated value is greater the greater the amount of the motor current.

4. Dishwasher according to one of the preceding claims, wherein the estimated value or the amount of the estimated value is greater the greater the input voltage.

5. Dishwasher according to one of the preceding claims, wherein the estimated value or the amount of the estimated value is greater the greater the speed of movement of the one or more baskets along the transport direction or of the transport belt in the direction of circulation.

6. Dishwasher according to one of the preceding claims, wherein the estimated value or the amount of the estimated value is smaller the greater the acceleration of motion of the one or more baskets along the transport direction or of the transport belt in the direction of circulation.

7. Dishwasher according to any of the preceding claims, wherein the one or more dishwasher parameters comprise one or more of the following parameters: a type of dishwasher; a number of baskets or a length of the conveyor belt; an actual load weight or an average load weight or a maximum load weight of the dishwasher; and a duration or a number of washing cycles of the dishwasher since an initial commissioning of the dishwasher.

8. Dishwasher according to claim 7, wherein the first threshold and / or the second threshold is greater the greater the number of baskets or the length of the transport belt and / or the greater the average load weight or the maximum load weight of the dishwasher.

9. Dishwasher according to claim 7 or 8, which further comprises a load determination unit for determining an actual load weight of the dishwasher; wherein the first threshold and / or the second threshold is greater the greater the actual load weight determined by the load determination unit.

10. Dishwasher according to one of claims 7 to 9, which further comprises an operating time determination unit for determining a duration or a number of washing cycles of the dishwasher since an initial commissioning of the dishwasher; wherein the first threshold and / or the second threshold is greater the greater the duration or number of washing cycles determined by the operating time determination unit.

11. Dishwasher according to any of the preceding claims, wherein, when the threshold condition is met: the dishwasher is configured to switch off the motor, and the transport device is configured to move the one or more baskets back along a direction opposite to the transport direction or to move the transport belt back in a direction opposite to the direction of circulation.

12. Dishwasher according to one of the preceding claims, wherein the estimated value depends linearly on the motor current.

13. Dishwasher according to one of the preceding claims, wherein the estimated value depends linearly on the speed of movement.

14. Dishwasher according to one of the preceding claims, wherein the estimated value is based on an RMS current, wherein the RMS current is a sum of the motor current and a correction current, wherein the correction current depends linearly on the input voltage of the inverter.

15. Dishwasher according to claim 14, where the effective current (I e ff) in the following relationship to the motor current (I q ), the input voltage (Um) of the inverter, a zeroed transport device parameter (C o ) and a first transport device parameter (Ci): Ieff =I q + Co + Ci * U in .

16. Dishwasher according to one of claims 14 or 15, wherein the estimated value depends linearly on the effective current.

17. Dishwasher according to one of claims 14 to 16, wherein, if the movement of the one or more baskets along the transport direction or the movement of the transport belt in the direction of circulation is uniform, the estimate is a uniformity estimate (P un i) is, which is related to the effective current (Ieff), the velocity of movement (v), a second transport device parameter (C2), a third transport device parameter (C3) and an eighth transport device parameter (Cs) as follows: where, if the movement of one or more baskets along the transport direction or the movement of the transport belt in the direction of rotation is accelerated, the estimate is an acceleration estimate (P). acc) is, which is related to the effective current (Ieff), the velocity of movement (v), a fourth transport device parameter (C4), a fifth transport device parameter (C5) and a ninth transport device parameter (C9) as follows: where, if the movement of the one or more baskets along the transport direction or the movement of the transport belt in the direction of rotation is delayed, the estimate is a delay estimate (Pdec) which is related to the effective current (I) as follows: e ff), the speed of movement (v), a sixth transport device parameter (Ce), a seventh transport device parameter (C7) and a tenth transport device parameter (C10): Pdec = C6 + C7 * Ieff + C 10 * V ; and / or where, if the velocity of motion is zero, the estimate is a standstill estimate (Pstui), where the standstill estimate (Pstiii) is zero.

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