EP4243664A1

EP4243664A1 - Dishwasher, method and computer program product

Info

Publication number: EP4243664A1
Application number: EP21801491.8A
Authority: EP
Inventors: Stephan Lutz; Stefan Pollithy; Markus Wecker; Igor Hoffmann; Marco Kienle
Original assignee: BSH Hausgeraete GmbH
Current assignee: BSH Hausgeraete GmbH
Priority date: 2020-11-11
Filing date: 2021-10-27
Publication date: 2023-09-20
Also published as: WO2022101007A1; CN116490110A; DE102020214200A1; US20240023785A1

Abstract

The invention relates to a dishwasher (1), more particularly a domestic dishwasher, comprising: - at least one spraying device (20) which is actively driven by means of a drive apparatus (15) and intended for applying a washing liquor to items to be washed that can be placed in a washing container (2) of the dishwasher (1), the drive apparatus (15) comprising an electric motor (16) for actively driving the at least one spraying device (20) and a sensing unit (16A) for sensing a motor rotational speed (SIG) of the electric motor (16); and - a control device (25) which is designed to detect a blockage of the at least one spraying device (20) on the basis of the sensed motor rotational speed (SIG).

Description

Dishwashing machine, method and computer program product

The present invention relates to a dishwasher, a method for operating a dishwasher and a computer program product.

Known dishwashing machines often have a rotatably mounted spray device which is driven, for example, by a hydraulic reaction mechanism or an electric motor. When operating a dishwasher, it can happen that items to be washed, such as a knife or a plate, protrude from the dish rack and protrude into a movement path of the spray device. This can lead to a blockage of the spray device. If the spray device stops rotating, this can affect the cleaning result. It is therefore desirable to detect a blockage in the spray device in order to initiate countermeasures.

The spray device of the dishwasher is preferably actively driven by an electric motor. This has the advantage that the spray device can be rotated at different speeds and/or can be stopped in places, for example to form an intensive rinsing zone.

US Pat. No. 8,357,246 B2 discloses a dishwasher with a motor-driven spray arm. A detection and evaluation of the motor current makes it possible to determine a blockage of the spray arm. US Pat. No. 8,734,594 B2 and US Pat. No. 9,681,790 B2 disclose further conventional dishwashers.

Against this background, an object of the present invention is to improve the operation of a dishwasher.

According to a first aspect, a dishwasher, in particular a household dishwasher, is proposed with at least one spray device driven by a drive device for applying washing liquor to items to be washed that can be arranged in a washing container of the dishwasher. The drive device includes an electric motor for actively driving the at least one spray Device and a detection unit for detecting a motor speed of the electric motor. A control device is set up to determine a blockage of the at least one spray device as a function of the detected engine speed.

This dishwasher has the advantage that a blockage of the spray device can be detected based on the motor speed. If there is a blockage, suitable countermeasures can be taken to reduce the effects of the blockage on the flushing result. The dishwasher is thus able to achieve an optimal washing result despite an existing blockage. On the one hand, this protects the items to be washed, since it is avoided that the spray device remains in the blocking position and only the items to be washed that are arranged at this point are exposed to washing liquor. On the other hand, resources are conserved, since it is possible to avoid carrying out a washing program again with the same items to be washed, since these items were not cleaned satisfactorily. The blockage of the spray device can be caused, for example, by items to be washed or by dirt that has penetrated a drive train of the spray device.

The drive device comprises in particular an electric motor, for example a brushless direct current motor (BLDC) or a brushless alternating current motor (BLAC). Other types of electric motors may also be suitable. The drive device is controlled by the control device, for example. The drive device is set up to actively drive the spray device. In the present case, the fact that the spray device is “actively driven” means that the drive device applies a torque to the spray device. In the present case, “active” driving is therefore not to be understood in particular as meaning that the spray arm is set in rotation with the aid of spray nozzles. The active driving can take place in particular with an adjustable speed. The drive device can also be set up to stop the spray device at a specific position or a specific angle of rotation and/or to move the spray device back and forth.

The spray device is rotatably mounted and is designed, for example, as a spray arm. The spray device is set up to dispense washing liquor onto the items to be washed. For this purpose, the spray device preferably comprises a plurality of spray nozzles, from which the washing liquor is sprayed with excess pressure. The spray device includes a hydraulic rauliksystem, which is set up to direct the washing liquor from a connecting piece, which is arranged, for example, in the axis of rotation of the spray device, to the spray nozzles. The spray device may optionally include one or more satellite spray devices.

In the present case, washing liquor is understood to mean any liquid that can be used to wash the items to be washed in the dishwasher. For example, the rinsing liquor includes freshly supplied tap water, deionized tap water, tap water mixed with a cleaning agent and the like. The washing liquor can include soiling that has been detached from the items to be washed.

The detection unit of the drive device includes, for example, a Hall sensor, an optical encoder, an incremental encoder or the like.

Additionally or alternatively, the detection unit can be based on the measurement of the voltage zero crossing of a voltage induced in a motor winding of the electric motor, in particular the back EMF. Advantageously, the back-EMF is evaluated anyway for the regulation of the electric motor, so that no additional elements are necessary in this case.

The control device can be implemented in terms of hardware and/or software. In the case of a hardware implementation, the control device can be designed, for example, as a computer or as a microprocessor. In the case of a software implementation, the control device can be embodied as a computer program product, as a function, as a routine, as part of a program code or as an executable object.

The control device is set up to determine a blockage of the spray device as a function of the detected engine speed. For example, for this purpose the control device analyzes a signal curve of the engine speed and/or compares it with a target value for the engine speed.

According to one embodiment of the dishwasher, an overload protection device is provided which is arranged between the electric motor and the spray device in the event of a blockage of the spray device, it automatically moves from a coupled state, in which power is transmitted between the electric motor and the spray device, to a decoupled state, in which the power transmission between the electric motor and the spray device is interrupted.

Because the overload protection is provided, it is possible to reliably prevent the drive device from being overloaded. In particular, this prevents damage to a drive element of the drive device or to a gear of the same. The fact that the overload protection "automatically" moves from the coupling state to the decoupling state and back means in particular that the overload protection can be brought from the coupling state to the decoupling state and vice versa without an active drive element and/or sensors. In the decoupling state of the overload protection, the spray device is no longer actively driven and the electric motor rotates without load.

The overload protection preferably triggers at a maximum torque of between 0.25 Nm and 2 Nm, preferably 0.4 Nm and 1 Nm. The force that acts on items to be washed, the spray arm and the drive unit before the overload protection is decoupled is thus limited to a small upper value. At the same time, the maximum torque is high enough for the engine speed of the electric motor to drop slightly before the overload protection device is decoupled, so that the change in engine speed can still be reliably determined. It should be noted that a regulation of the electric motor, which regulates the speed of the electric motor to a predetermined setpoint, for example, must not compensate for the speed drop too quickly, since otherwise it may no longer be possible to detect the speed fluctuation caused by the blockage. The control must therefore be set in such a way that the speed fluctuation is still sufficiently large in the event of a blockage.

According to a further embodiment of the dishwasher, the drive device is arranged outside of the washing tub, with an output shaft being provided for transmitting torque from the electric motor to the spray device, and the overload protection device being arranged between the output shaft and the spray device, with a rotation angle of the output shaft and a rotation angle of the spray device in have a predetermined relationship to each other when the overload protection device is in the coupling state.

In this embodiment, a rotation angle of the spray device can advantageously be inferred from a rotation angle of the output shaft when the overload protection device is in the coupling state. The angle of rotation of the output shaft can, for example, also be detected within the drive device, for example with a rotary encoder or an incremental sensor. Alternatively or additionally, the angle of rotation of the output shaft can be inferred from an angle of rotation of the electric motor.

The output shaft protrudes in particular through a wall of the washing container and is sealed with a seal so that no washing liquid can escape from the washing container on the output shaft.

An axis of rotation of the output shaft of the drive device and an axis of rotation of the spray arm are preferably arranged parallel to one another and at a distance from one another.

In embodiments of the dishwasher, the drive device comprises a gear unit arranged between the electric motor and the spray device for providing a predetermined gear ratio for driving the spray device.

In embodiments, the transmission unit is arranged between the electric motor and the output shaft.

The gear unit is preferably designed in such a way that the output shaft, and thus also the spray device, is rotated at a speed of 0-20 revolutions/second. The gear unit is preferably set up to provide a reduction in the range of 200/1-1000/1. This means, for example, that the electric motor makes 200 revolutions, while the output shaft only makes one revolution.

According to a further embodiment of the dishwasher, the control device is set up to determine the blockage of the spray device as a function of a comparison of a predetermined target speed and the detected motor speed. For example, the target speed at a given time is 500 rps. If the detected engine speed has a different value, in particular a lower value, this can indicate an existing blockage. It should be noted that the setpoint speed can have different values depending on the wash program at different points in time during the execution of a wash program.

In embodiments, the control device is set up to carry out a signal analysis of the detected engine speed and to determine the blockage of the spray device depending on a result of the signal analysis.

The signal analysis includes in particular the formation of a time derivative and/or the implementation of a frequency analysis. In particular, sudden changes in the speed can be identified based on jumps in the time derivative.

According to a further embodiment of the dishwasher, the control device is set up to determine the blockage of the spray device as a function of a deviation of the detected motor speed from the target speed by more than a predetermined threshold value.

For example, the predetermined threshold value is specified as an absolute value, specified as a relative value that depends, for example, on the setpoint speed, and/or a combination of these options. For example, the predetermined threshold can be 50 rev/s. Alternatively, the predetermined threshold value can be 10% of the target value, that is, for example, 100 rev/s for a target value of 1000 rev/s. Alternatively, the predetermined threshold may include a combination thereof, such as 10% of target and at least 50 rps.

According to a further embodiment of the dishwasher, the control device is set up to output a notification signal to a user of the dishwasher depending on the determination of the blockage of the spray device.

For example, the dishwasher includes a loudspeaker for outputting an acoustic information signal and/or a display element for outputting a visual cue signal. In preferred embodiments, the dishwasher comprises a communication unit which is set up to transmit the notification signal to a device external to the dishwasher, such as a mobile device, in particular a smartphone, a computer or the like, of the user, the external device being set up to output the notification signal to set up for the user. For example, a corresponding application runs on the external device, which causes a message to be output to the user when the message signal is received from the dishwasher.

This way the user can be notified when there is a blockage. The user can then, for example, solve the blockage manually and/or notify customer service.

According to one aspect, a system comprising the dishwasher according to the first aspect and an external device is proposed. The dishwasher includes a communication unit that is set up to transmit a notification signal to the external device. The external device is configured to output the notification signal to the user. For example, a corresponding application runs on the external device, which causes a message to be output to the user when the message signal is received from the dishwasher.

According to a further embodiment of the dishwasher, the control device is set up to determine a blocking position of the spray device.

The blocking position includes in particular a rotation angle of the spray device.

The blockage position can be derived, for example, from the position of the electric motor at which the blockage is determined. If no overload protection is arranged between the electric motor and the spray device, ie the electric motor and the spray device are permanently coupled, there is a proportionality determined by the drive train between the motor position and the position of the spray device. If there is an overload protection, then the electric motor rotates in the uncoupled state independently of the spray device. In this case, the overload protection is preferably designed in such a way that the coupling state is only in a specific relative rotational position between the electric motor and the spray device or, if present, an output shaft and the spray device, can be produced. With each revolution of the electric motor or the output shaft, this position is reached once, so that the overload protection switches to the coupling state. If the blockage is still present, the overload protection will then return to the decoupling state. This coupling/decoupling can be determined based on the detected engine speed. The motor position at which it was decoupled for the first time thus corresponds to the blocked position of the spray device.

According to a further embodiment of the dishwasher, the control device is set up to output a message to a user of the dishwasher as a function of the determined blockage position.

The indication preferably includes the blockade position. For example, the indication can include a graphical representation of the blockade position. This enables the user to easily check the blockage and remove it if necessary.

According to a further embodiment of the dishwasher, the control device is set up to reverse a direction of rotation of the electric motor when the spray device is blocked.

If the direction of rotation of the electric motor is changed, then the direction of rotation of the actively driven spray device also changes. This means that the spray device is moved away from the position where the blockage is present. Depending on the nature of the blockage, for example items to be washed that protrude into the range of movement of the spray device, the blockage can also occur in the other direction of rotation. If the blockage was caused by contamination, the contamination may be removed by changing the direction of rotation.

According to a further embodiment of the dishwasher, a detection unit for detecting a movement of the spray device is provided, the control device being set up to determine the blockage of the spray device depending on the detected motor speed and the detection of the movement of the spray device. In this embodiment, the blockage of the spray device can be verified. The detection unit can be used, for example, as a rotary encoder on a drive shaft of the spray device, a Hall sensor that detects the sweeping of a specific position in the washing compartment by the spray device, with the spray device having a magnet, or a camera that records a movement of the spray device Determined based on an image analysis include. In particular, it is advantageous to design the detection unit as a Hall sensor in combination with a magnet arranged in or on the spray device, since the Hall sensor can be arranged outside of the washing container.

According to a further embodiment of the dishwasher, the control device is set up to determine an angular range in which the spray device is freely rotatable and to control the electric motor in such a way that the spray device rotates only in the determined angular range.

In this embodiment, in particular, two blocking positions are determined, with the angular range between the two blocking positions being the free angular range.

For example, the spray device is designed as a spray arm that includes two opposite arms, each of which is of the same length. When turning in a first direction of rotation, a blockage is determined, for example, at an angle of approximately 90°. The spray arm is then turned in the other direction, and a blockage is detected again at an angle of about 270°, ie after about half a turn of the spray arm. A respective blocking position corresponds to a contact of a respective boom of the spray arm. In this case, the control device controls the drive device so that the spray arm is rotated back and forth between 90° and 270°. In this way, the items to be washed can be cleaned despite the presence of a blockage.

According to a further embodiment of the dishwasher, the control device is set up to set a torque provided by the electric motor. For example, for this purpose the control device controls the drive current with which the electric motor is operated and/or a voltage applied to the electric motor. This can be done, for example, by setting a pulse duty factor.

In particular, limiting the torque can be advantageous in order to force the electric motor to stop even if there is an overload protection device. To do this, the torque must be set so that it is not sufficient to trigger or decouple the overload protection. Therefore, when the blockage occurs, the electric motor is also stopped. A motor position corresponding to the blockage position can thus be determined.

According to a further embodiment of the dishwasher, the control device is set up, after a door of the dishwasher has been closed, to activate the electric motor in such a way that the spray device performs at least one complete revolution in the washing compartment.

This has the advantage that immediately after the door is closed, it is recognized whether there is a blockage. If there is a blockage, the user, who in this case is still in the vicinity of the dishwasher, can be notified accordingly and preferably resolve the blockage directly.

This movement of the spray device can also be described as a test run.

In embodiments, the test drive is only provided if the user has programmed the start of a washing program.

In further embodiments, the test drive can be provided each time the door is closed. In preferred embodiments, the test run is always provided when a change in the load of items to be washed in the dishwasher is determined. The change in the load can be determined, for example, on the basis of an image of items to be washed and/or a weight measurement.

In embodiments of the dishwasher, the spray device comprises a lower spray arm, an upper spray arm and/or a roof rotor. A respective spray arm includes, in particular, an actively driven boom and can include a spray arm satellite rotatably mounted on the boom. The spray arm satellite is preferably not actively driven, but is driven with the aid of washing liquor ejected from spray nozzles of the same

According to a second aspect, a method for operating a dishwasher, in particular a domestic dishwasher, is proposed with at least one spray device driven by a drive device for applying washing liquor to items to be washed that can be arranged in a washing compartment of the dishwasher. In a first step, an electric motor of the drive device is activated to actively drive the spray device. In a second step, a motor speed of the electric motor of the drive device is detected. In a third step, a blockage of the spray device is determined as a function of the detected engine speed.

The embodiments and features described for the proposed dishwasher apply accordingly to the proposed method. This method has the same advantages as explained with reference to the dishwasher.

According to a third aspect, a computer program product is proposed which comprises instructions which, when the program is executed by a computer, cause the latter to execute the method according to the second aspect.

A computer program product, such as a computer program means, can be made available or supplied by a server in a network, for example, as a storage medium such as a memory card, USB stick, CD-ROM, DVD, or in the form of a downloadable file. This can be done, for example, in a wireless communication network by transferring a corresponding file with the computer program product or the computer program means.

Further possible implementations of the invention also include combinations of features or embodiments described above or below with regard to the exemplary embodiments that are not explicitly mentioned. The specialist will also add aspects as improvements or additions to the respective basic form of the invention.

Further advantageous refinements and aspects of the invention are the subject matter of the dependent claims and of the exemplary embodiments of the invention described below. The invention is explained in more detail below on the basis of preferred embodiments with reference to the enclosed figures.

1 shows a schematic perspective view of an embodiment of a dishwasher;

2 shows a schematic section through a further embodiment of a dishwasher;

3 shows an exemplary diagram of a rotation angle of an output shaft and a detected engine speed; and

FIG. 4 shows a schematic block diagram of an exemplary embodiment of a method for operating a dishwasher.

Elements that are the same or have the same function have been provided with the same reference symbols in the figures, unless otherwise stated.

1 shows a schematic perspective view of an embodiment of a dishwasher 1, which is embodied here as a domestic dishwasher. The domestic dishwasher 1 includes a washing compartment 2, which can be closed by a door 3, which is in particular watertight. For this purpose, a sealing device can be provided between the door 3 and the washing container 2 . The washing container 2 is preferably cuboid. The washing compartment 2 can be arranged in a housing of the domestic dishwasher 1 . The washing compartment 2 and the door 3 can form a washing chamber 4 for washing items to be washed.

The door 3 is shown in FIG. 1 in its open position. By pivoting about a pivot axis 5 provided at a lower end of the door 3, the door 3 be closed or opened. With the help of the door 3, a loading opening 6 of the washing compartment 2 can be closed or opened. The washing compartment 2 has a base 7, a cover 8 arranged opposite the base 7, a rear wall 9 arranged opposite the closed door 3 and two side walls 10, 11 arranged opposite one another. The bottom 7, the top 8, the rear wall 9 and the side walls 10, 11 can be made from a stainless steel sheet, for example. Alternatively, for example, the bottom 7 can be made of a plastic material.

The household dishwasher 1 also has at least one washware holder 12 to 14 . Preferably, several, for example three, washware holders 12 to 14 can be provided, with washware holder 12 being a lower washware holder or a lower rack, washware holder 13 being an upper washware holder or an upper rack and washware holder 14 being a cutlery drawer. As FIG. 1 also shows, the wash items receptacles 12 to 14 are arranged one above the other in the wash tub 2 . Each washware holder 12 to 14 can be moved either into or out of the washing compartment 2 . In particular, each washware receptacle 12 to 14 can be pushed or moved into the washing compartment 2 in an insertion direction E and pulled out or moved out of the washing compartment 2 in an extension direction A counter to the insertion direction E.

A spray device 20 is arranged on the floor 7 . It is, for example, a spray arm. The spray arm 20 may include a satellite spray arm (not shown). The spray arm 20 is designed to dispense washing liquor onto items to be washed that are arranged in the items to be washed receptacles 12 to 14 . The spray arm 20 is rotatably mounted, with a torque for rotating the spray arm 20 being provided by a drive device 15 . The drive device 15 is preferably arranged outside the washing compartment 2, in this example under the floor 7. The drive unit 15 comprises in particular an electric motor 16 (see FIG. 2) and a detection unit 16A (see FIG. 2) for detecting a motor speed 21 ( see Fig. 3) of the electric motor 16.

On the door 3 of the domestic dishwasher 1 is also a control device

25 arranged. The control device 25 is, for example, for performing a Flushing program set up from a number of flushing programs. In particular, the control device 25 is set up to determine a blockage of the spray arm 20 as a function of the detected engine speed 21 . For example, the spray arm 20 is coupled to the electric motor 16 of the drive device 15 without an overload protection device 19 (see FIG. 2). In the event of a blockage of the spray arm 20, the motor speed 21 therefore drops to zero, since the spray arm 20 is stopped, and thus also the electric motor 16. If a blockage is detected, the control device 25 can, for example, control the drive device 15 in such a way that the spray arm 20 is rotated in the opposite direction. If a blockage also occurs in this direction of rotation, the spray arm 20 can be rotated back and forth, for example, between the two points at which the spray arm 20 encounters the obstacle that caused the blockage. This is also called the pendulum operation of the spray arm 20 . This ensures that the items to be washed are cleaned despite the spray arm 20 being blocked. In addition, the control device 25 can inform the user of the dishwasher 1 about the blockage. This can be done by outputting an acoustic and/or visual notification signal and/or by transmitting a message to an external device, in particular a mobile device, belonging to the user. The user can then react and solve the blockage or notify customer service, provided the blockage is not caused by items to be washed or the like.

FIG. 2 shows a schematic section through a further embodiment of a dishwasher 1. The dishwasher 1 has in particular all the features that were explained with reference to the domestic dishwasher of FIG. 1, even if they are not shown in part in FIG .

In particular, a drive train from the drive device 15 to the actively driven spraying device 20 is shown in detail in FIG. 2 . The drive device 15 is arranged under the floor 7 of the washing compartment 2 . The drive device 15 comprises an electric motor 16 and a detection unit 16A which is set up to detect a motor speed 21 (see FIG. 3) of the electric motor 16 . The electric motor 16 drives an output shaft 17 . This can be done in particular using a gear (not shown) that increases or decreases the engine speed 21 by a predetermined factor. The output shaft 17 rotates in accordance with the electric motor 16, with a direction of rotation being freely adjustable. The rotation of the output shaft 17 is proportional to the rotation of the electric motor 16, with a gear ratio representing the proportionality factor. If there is no gearbox, as shown in FIG. 2, the proportionality factor is 1. The arrow from the electric motor 16 to the output shaft 17 indicates the power transmission.

The output shaft 17 penetrates the bottom 7 of the washing compartment 2 and protrudes into it. The output shaft 17 is sealed, for example, with a shaft sealing ring or the like, so that flushing water is prevented from escaping. In particular, the output shaft 17 is coupled to a clutch unit 18 which is arranged in the washing compartment 2 . In this example, the clutch unit 18 comprises an overload safety device 19. If the spray device 20 is blocked, the overload safety device 18 automatically moves from a coupled state in which power is transmitted between the electric motor 16 and the spray device 20 to a decoupled state in which the power is transmitted between the electric motor 16 and the spray device 20 is interrupted. In the coupled state, the overload protection device 18, as indicated by the arrows, transmits a force from the output shaft 17 to a drive shaft 20A of the spray device 20.

The spray device 20 is, for example, rigidly connected to the drive shaft 20A and accordingly rotates with it. The overload protection device is preferably designed in such a way that the coupling state can be produced in exactly one specific relative rotational position between the output shaft 17 and the drive shaft 20A. Thus, in the coupled state, a specific rotational position of the output shaft 17 corresponds to a specific rotational position of the drive shaft 20A and thus of the spray device 20.

In embodiments (not shown), the drive device 15 additionally includes a sensor for detecting a rotational position of the output shaft 17. The sensor is designed, for example, as a magnetic or optical encoder. In the coupled state, the rotational position of the spray device 20 can be inferred from the detected rotational position of the output shaft 17 . The position of the blockage of the spray device 20 is thus known. Appropriate measures can be taken on the basis of the known blockade position. For example, in the case of a visual output of an indication to the user of the dishwasher 1, the blocking position can be graphical displayed so that the user can easily check the blockage and remove it if necessary.

Fig. 3 shows two diagrams, the upper diagram showing an angle of rotation (p) of an output shaft 17 (see Fig. 2) and the lower diagram showing a motor speed RPM of an electric motor 16 driving the spray device 20 (see Fig. 2). The two diagrams have a common time axis t. The diagrams each represent an exemplary curve that corresponds, for example, to a dishwasher that has an overload protection device 19 (see FIG. 2) in the drive train, such as the dishwasher 1 of FIG.

The upper diagram shows the course of the angle of rotation 21 of the output shaft 17. As explained above, the output shaft 17 rotates at a substantially constant angular speed. Changes in the engine speed SIG affect the angular velocity of the output shaft 17 proportionally.

The lower diagram shows the detected engine speed SIG. A regulation adjusts the engine speed SIG to a target value RS for the engine speed SIG. At two points in time t1, t2, fluctuations in the engine speed SIG can be seen. These fluctuations occur in the two illustrated revolutions of the output shaft 17 in each case at the same angle of rotation (p of the output shaft 17. The fluctuations are caused by a coupling/decoupling of the overload protection 19 when the spray device 20 (see FIG. 1 or 2) is blocked. triggered. If the overload protection 19 is in the coupled state and the spray device 20 is blocked, the drive train is tense until the overload protection 19 is triggered. This leads to a drop in the engine speed SIG. When the overload protection is decoupled, the drive train relaxes again and the The engine speed SIG suddenly increases again The electric motor 16 now rotates without load, which is why the engine speed SIG can briefly have an increased value until it is readjusted by the controller.

Two threshold values th1, th2 are shown in order to determine whether the speed fluctuation is due to a blockage of the spray device 20. If one of these threshold values th1, th2 or both threshold values th1, th2 is exceeded, it can be concluded that the spray device 20 is blocked. The control device 25 (see FIG. 1) is therefore set up, for example, to compare the detected engine speed SIG with at least one threshold value th1, th2. For reliable detection of the blockage, it can be advantageous to wait two or more than two revolutions of the output shaft 17 to see whether the coupling/decoupling is repeated at the same rotational position of the output shaft 17, as shown in FIG is.

In addition and/or as an alternative to the comparison of the engine speed SIG with threshold values th1, th2, which relate to the setpoint RS, the control device 25 can be set up to determine the local maxima/minima of the engine speed SIG using a curve analysis (not shown). . In this case, for example, if the first time derivative of the engine speed SIG is considered, there would be a zero crossing at the local maxima/minima, which can be detected.

Fig. 4 shows a schematic block diagram of an embodiment of a method for operating a dishwasher 1, for example the dishwasher 1 of Fig. 1 or Fig. 2. The dishwasher 1 has at least one by means of a drive device 15 (see Fig. 1 or 2) driven Spraying device 20 (see FIG. 1 or 2) for applying a washing liquor to items to be washed that can be arranged in a washing compartment 2 (see FIG. 1 or 2) of the dishwasher 1. In a first step S1, an electric motor 16 (see FIG. 2) of the drive device 15 for actively driving the spray device 20 is activated. In a second step S2, a motor speed SIG (see FIG. 3) of the electric motor 16 of the drive device 15 is detected. In a third step S3, a blockage of the spray device 20 is determined as a function of the detected engine speed SIG.

In one embodiment, the method additionally includes the steps described below. As soon as a blockage of the spray device 20 has been determined, for example as described with reference to FIG. 3, the electric motor 16 is controlled in such a way that the torque provided is not sufficient to release the overload protection device 19 (see FIG. 2). This can be done, for example, by setting a duty cycle to reduce the effective voltage with which the electric motor 16 is operated. When the output shaft 17 has completed a complete revolution and the overload protection device 19 returns to the coupled state, the torque of the electric motor 16 is not sufficient to decouple the overload protection device 19 again. Therefore, the electric motor 16 stops. The angular position of the electric motor 16, which corresponds to the locked position, is stored. The torque limitation is now lifted again and the electric motor 16 is rotated in the other direction. As a result, the spray device 20 is also driven in the other direction. The spray device 20 rotates until it encounters the obstruction causing the blockage from the other side. The blockage is determined on the basis of the detected engine speed SIG and the torque of the electric motor 16 is again limited in order to determine and store a second blockage position, which relates to the other direction of rotation of the spray device 20 . In this way, in particular, an angular range in which the spray device 20 can rotate freely is determined. The spray device 20 can now be pivoted back and forth in the known range.

Although the present invention has been described using exemplary embodiments, it can be modified in many ways.

Reference signs used:

1 dishwasher

2 rinsing tanks

3 door

4 washroom

5 pivot axis

6 loading opening

7 floor

8 ceiling

9 back panel

10 side wall

11 side wall

12 items to be washed

13 Items to be washed

14 Items to be washed

15 drive device

16 electric motor

16A registration unit

17 output shaft

18 clutch unit

19 overload protection

20 spray device

20A axis

21 rotation angles

25 control device cp rotation angle

A Pull-out direction

E insertion direction

RPM speed

RS target speed

51 process step

52 process step S3 method step

SIG engine speed t time axis t1 time t2 time th1 threshold th2 threshold

Claims

PATENT CLAIMS

1. Dishwasher (1), in particular a household dishwasher, with at least one spray device (20) that is actively driven by means of a drive device (15) for applying washing liquor to items to be washed that can be arranged in a washing container (2) of the dishwasher (1), the drive device (15) an electric motor (16) for actively driving the at least one spray device (20) and a detection unit (16A) for detecting a motor speed (SIG) of the electric motor (16), and with a control device (25) for determining a Blocking the at least one spray device (20) is set up depending on the detected engine speed (SIG).

2. Dishwasher according to claim 1, characterized by an overload protection arranged between the electric motor (16) and the spray device (20).

(19) which, when the spray device (20) is blocked, automatically changes from a coupled state, in which power is transmitted between the electric motor and the spray device, to a decoupled state, in which power is transmitted between the electric motor (16) and the spray device ( 20) is interrupted, spends.

3. Dishwasher according to Claim 2, characterized in that the drive device (15) is arranged outside of the washing container (2), an output shaft (17) being provided for transmitting a torque from the electric motor (16) to the spray device (20) and the overload protection (19) is arranged between the output shaft (17) and the spray device (20), with a rotation angle (21) of the output shaft (17) and a rotation angle of the spray device

(20) are in a predetermined relationship to one another when the overload protection device (19) is in the coupling state.

4. Dishwasher according to one of claims 1 - 3, characterized in that the control device (25) for determining the blockage of the spray device Device (20) depending on a comparison of a predetermined setpoint speed (RS) and the detected engine speed (SIG) is set up. Dishwasher according to Claim 4, characterized in that the control device (25) for determining the blockage of the spray device (20) as a function of a deviation of the detected motor speed (SIG) from the setpoint speed (RS) by more than a predetermined threshold value (th1, th2) is set up. Dishwasher according to one of claims 1 - 5, characterized in that the control device (25) is set up to output a notification signal to a user of the dishwasher (1) depending on the determination of the blockage of the spray device (20). Dishwasher according to one of Claims 1 - 6, characterized in that the control device (25) is set up to determine a blocking position of the spray device (20). Dishwasher according to Claim 7, characterized in that the control device (25) is set up to output a message to a user of the dishwasher (1) as a function of the blocking position determined. Dishwasher according to one of Claims 1 - 8, characterized by a detection unit for detecting a movement of the spray device (20), the control device (25) for determining the blockage of the spray device (20) depending on the detected motor speed (SIG) and the detection of the Movement of the spray device (20) is set up. Dishwasher according to one of Claims 1 - 9, characterized in that the control device (25) is set up to reverse a direction of rotation of the electric motor (16) when the spray device (20) is blocked. Dishwasher according to one of claims 1 - 10, characterized in that the control device (25) is set up to an angular range in which the spray device (20) is freely rotatable, and to control the electric motor (16) in such a way that the spray device (20) rotates only in the determined angular range. Dishwasher according to one of Claims 1 - 11, characterized in that the control device (25) is set up for setting a torque of the electric motor (16). Dishwasher according to one of Claims 1 - 12, characterized in that the control device (25) is set up to actuate the electric motor (16) after a door (3) of the dishwasher (1) has been closed in such a way that the spray device (20) at least performs a complete revolution in the rinsing tank (2). Method for operating a dishwasher (1), in particular a household dishwasher, with at least one spray device (20) actively driven by means of a drive device (15) for applying a washing liquor to items to be washed which can be arranged in a washing container (2) of the dishwasher (1), the procedure includes:

Controlling (S1) an electric motor (16) of the drive device (15) for actively driving the spray device (20);

Detecting (S2) a motor speed (SIG) of the electric motor (16) of the drive device (15), and

Determining (S3) a blockage of the spray device (20) depending on the detected engine speed (SIG). A computer program product comprising instructions which, when the program is executed by a computer, cause it to carry out the method according to claim 14.