Dishwasher, method and computer program product

Abstract

A dishwasher, in particular a household dishwasher, includes a dishwasher cavity, a spray apparatus for dispensing washing liquor, and a drive facility including an electric motor designed to actively drive the spray apparatus so as to apply washing liquor to an item to be washed arranged in the dishwasher cavity. The drive facility includes a detection unit for detecting a motor rotational speed of the electric motor. A control apparatus determines a blockage of the spray apparatus in dependence upon the detected motor rotational speed.

Claims

1. A dishwasher, comprising: a dishwasher cavity; a spray apparatus for dispensing washing liquor; a drive facility including an electric motor designed to actively drive the spray apparatus using an output shaft positioned to transfer torque from the electric motor to the spray apparatus so as to apply washing liquor to an item to be washed arranged in the dishwasher cavity, said drive facility including a detection unit for detecting a motor rotational speed of the electric motor, wherein a first axis of rotation of the output shaft is different from a second axis of rotation of the spray apparatus; and a control apparatus configured to: determine a blockage of the spray apparatus in dependence upon the detected motor rotational speed by: actuating the electric motor such that the spray apparatus performs a test run, in response to a door of the dishwasher closing, to move the spray apparatus such that the spray apparatus performs at least one complete rotation in the dishwasher cavity to detect whether the blockage is present; comparing the detected motor rotational speed to a predetermined target rotational speed; and determining an existence of the blockage of the spray apparatus in response to the detected motor rotational speed being lower than the predetermined target rotational speed; and determine a blockage position of the spray apparatus using a predetermined relationship between a position of rotation of the output shaft and a corresponding position of rotation of the spray apparatus.

2. The dishwasher of claim 1, constructed in a form of a household dishwasher.

3. The dishwasher of claim 1, further comprising an overload protection arranged between the electric motor and the spray apparatus and configured to move in a presence of blockage of the spray apparatus automatically from a coupling state, in which force is transferred between the electric motor and the spray apparatus, into a decoupling state, in which a transfer of force between the electric motor and the spray apparatus is interrupted.

4. The dishwasher of claim 3, wherein the drive facility is arranged outside the dishwasher cavity and includes the output shaft connected to the electric motor to transfer the torque from the electric motor to the spray apparatus, said overload protection being arranged between the output shaft and the spray apparatus, wherein an angle of rotation of the output shaft and an angle of rotation of the spray apparatus are in the predetermined relationship with one another when the overload protection is in the coupling state.

5. The dishwasher of claim 1, wherein the control apparatus is configured to determine the blockage of the spray apparatus in dependence upon a deviation of the detected motor rotational speed from the predetermined target rotational speed by more than a predetermined threshold value, and wherein the predetermined threshold comprises an absolute value and a relative value with respect to the predetermined target rotational speed.

6. The dishwasher of claim 1, wherein the control apparatus is configured to output an alert signal to a user of the dishwasher when the blockage of the spray apparatus is determined.

7. The dishwasher of claim 1, wherein the control apparatus is configured to output an alert signal to a user of the dishwasher in dependence upon the determined blockage position.

8. The dishwasher of claim 7, wherein the dishwasher comprises a display element configured to output the alert signal as a visual alert signal, and wherein the visual alert signal comprises a graphic representation of the determined blockage position of the spray apparatus.

9. The dishwasher of claim 1, further comprising the detection unit for detecting a movement of the spray apparatus, said control apparatus being configured to determine the blockage of the spray apparatus in dependence upon the detected motor rotational speed and detection of the movement of the spray apparatus.

10. The dishwasher of claim 1, wherein the control apparatus is configured to reverse a direction of rotation of the electric motor when the spray apparatus is blocked.

11. The dishwasher of claim 1, wherein the control apparatus is configured to determine an angular range in which the spray apparatus is able to freely rotate and to actuate the electric motor in such a manner that the spray apparatus only rotates in the determined angular range.

12. The dishwasher of claim 1, wherein the control apparatus is configured to set the torque of the electric motor.

13. The dishwasher of claim 1, wherein the control apparatus is configured to actuate the electric motor such that the spray apparatus performs the test run in response to a change in a loading of one or more items to be washed in the dishwasher.

14. The dishwasher of claim 13, wherein the change in the loading of the one or more items to be washed arranged in a receptacle for the one or more items to be washed of the dishwasher is determined based on an image of the receptacle or a weight measurement.

15. A method for operating a dishwasher which includes a spray apparatus and a drive facility operably connected to the spray apparatus, said method comprising: actuating an electric motor of the drive facility for actively driving the spray apparatus so as to perform a test run, in response to a door of the dishwasher closing, to move the spray apparatus such that the spray apparatus performs at least one complete rotation in a dishwasher cavity of the dishwasher to detect whether a blockage is present, wherein torque generated by the electric motor to drive the spray apparatus is transferred to the spray apparatus using an output shaft of the drive facility that has a first axis of rotation different from a second axis of rotation of the spray apparatus; detecting a motor rotational speed of the electric motor of the drive facility; determining the blockage of the spray apparatus in dependence upon the detected motor rotational speed by comparing the detected motor rotational speed to a predetermined target rotational speed and determining an existence of the blockage of the spray apparatus in response to the detected motor rotational speed being lower than the predetermined target rotational speed; and determining a blockage position of the spray apparatus using a predefined relationship between a position of rotation of the output shaft and a corresponding position of rotation of the spray apparatus.

16. The method of claim 15 for operating a household dishwasher.

17. A computer program product embodied on a non-transitory computer readable medium comprising commands which, when executed by a computer, cause the computer to perform operations comprising: actuating an electric motor of a drive facility of a dishwasher for actively driving a spray apparatus operably connected to the drive facility so as to perform a test run, in response to a door of the dishwasher closing, to move the spray apparatus such that the spray apparatus performs at least one complete rotation in a dishwasher cavity of the dishwasher to detect whether a blockage is present, wherein torque generated by the electric motor to drive the spray apparatus is transferred to the spray apparatus using an output shaft of the drive facility that has a first axis of rotation different from a second axis of rotation of the spray apparatus; detecting a motor rotational speed of the electric motor of the drive facility; determining the blockage of the spray apparatus in dependence upon the detected motor rotational speed by comparing the detected motor rotational speed to a predetermined target rotational speed and determining an existence of the blockage of the spray apparatus in response to the detected motor rotational speed being lower than the predetermined target rotational speed; and determining a blockage position of the spray apparatus using a predefined relationship between a position of rotation of the output shaft and a corresponding position of rotation of the spray apparatus.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further advantageous embodiments and aspects of the invention are the subject matter of the subordinate claims and of the exemplary embodiments of the invention described below. Furthermore, the invention is explained in detail with the aid of preferred embodiments with reference to the attached figures.

(2) FIG. 1 shows a schematic perspective view of an embodiment of a dishwasher;

(3) FIG. 2 shows a schematic section through a further embodiment of a dishwasher;

(4) FIG. 3 shows an exemplary diagram of an angle of rotation of an output shaft and a detected motor rotational speed; and

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

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS OF THE PRESENT INVENTION

(6) In the figures, identical or functionally identically elements are provided with the same reference characters, insofar as not otherwise stated.

(7) FIG. 1 shows a schematic perspective view of an embodiment of a dishwasher 1 which is designed here as a household dishwasher. The household dishwasher 1 comprises a dishwasher cavity 2 which can be sealed, in particular in a water-tight manner, by a door 3. For this purpose, a sealing facility is provided between the door 3 and the dishwasher cavity 2. The dishwasher cavity 2 is preferably cuboid. The dishwasher cavity 2 can be arranged in a housing of the household dishwasher 1. The dishwasher cavity 2 and the door 3 can form a dishwasher interior 4 for washing items to be washed.

(8) The door 3 is illustrated in its open position in FIG. 1. The door 3 can be closed or opened by pivoting about a pivot axis 5 that is provided at a lower end of the door 3. A loading opening 6 of the dishwasher cavity 2 can be closed or opened with the aid of the door 3. The dishwasher cavity 2 has a base 7, a ceiling 8 that is arranged opposite the base 7, a rear wall 9 that is arranged opposite the closed door 3, and two side walls 10, 11 that are arranged opposite one another. The base 7, the ceiling 8, the rear wall 9 and the side walls 10, 11 can be manufactured, for example, from a stainless steel sheet. Alternatively, the base 7 can be manufactured for example, from a synthetic material.

(9) Moreover, the household dishwasher 1 has at least one receptacle 12 to 14 for items to be washed. It is preferred that multiple, for example three, receptacles 12 to 14 for items to be washed are provided, wherein the receptacle 12 for items to be washed can be a lower receptacle for items to be washed or a bottom basket, the receptacle 13 for items to be washed can be a receptacle for items to be washed or a top basket and the receptacle 14 for items to be washed can be a cutlery drawer. As FIG. 1 further shows, the receptacles 12 to 14 for items to be washed are arranged one above the other in the dishwasher cavity 2. Each receptacle 12 to 14 for items to be washed can be selectively displaced into or out of the dishwasher cavity 2. In particular, each receptacle 12 to 14 for items to be washed can be pushed or moved into the dishwasher cavity 2 in an insertion direction E and pulled out or moved out of the dishwasher cavity 2 in an extraction direction A opposite to the insertion direction E.

(10) A spray apparatus 20 is arranged on the base 7. Said spray apparatus is a spray arm. The spray arm 20 can have a satellite spray arm (not illustrated). The spray arm 20 is configured so as to discharge washing liquor onto the items to be washed that are arranged in the receptacle 12 to 14 for items to be washed. The spray arm 20 is rotatably mounted, wherein a torque for rotating the spray arm 20 is provided by a drive facility 15. The drive facility 15 is preferably arranged outside the dishwasher cavity 2, in this example therefore below the base 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 rotational speed 21 (see FIG. 3) of the electric motor 16.

(11) Moreover, a control apparatus 25 is arranged on the door 3 of the household dishwasher 1. The control apparatus 25 is configured, for example, so as to perform a washing program from a number of washing programs. In particular, the control apparatus 25 is configured so as, in dependence upon the detected motor rotational speed 21, to determine a blockage of the spray arm 20. For example, the spray arm 20 is coupled to the electric motor 16 of the drive facility 15 without an overload protection 19 (see FIG. 2). In the event of a blockage of the spray arm 20, the motor rotational speed 21 therefore drops to zero because the spray arm 20 has stopped and consequently also the electric motor 16. If a blockage is established, the control apparatus 25 can actuate the drive facility 15, for example, in such a manner that the spray arm 20 is rotated in the opposite direction. Even if a blockage 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 impinges against the obstacle that has caused the blockage. This can also be referred to as a pendulum operation of the spray arm 20. Consequently, it is ensured that the items to be washed are cleaned despite the spray arm 20 being blocked. In addition, the control apparatus 25 can inform the user of the dishwasher 1 about the blockage. This can be performed by outputting an acoustic and/or visual alert signal and/or by transmitting a message to an external device, in particular a mobile device, of the user. The user can then react and eliminate the blockage or inform customer services, insofar as the blockage has not been caused by an item to be washed or the like.

(12) FIG. 2 shows a schematic section through a further embodiment of a dishwasher 1. The dishwasher 1 has in particular all the features that have been explained with reference to the household dishwasher in FIG. 1, even if some of them are not illustrated in FIG. 2.

(13) FIG. 2 illustrates in detail in particular a drive train from the drive facility 15 to the actively driven spray apparatus 20. The drive facility 15 is arranged below the base 7 of the dishwasher cavity 2. The drive facility 15 comprises an electric motor 16 and a detection unit 16A that is configured so as to detect a motor rotational speed 21 of the electric motor 16 (see FIG. 3). The electric motor 16 drives an output shaft 17. This can be performed in particular by using a transmission (not shown) that increases or reduces the motor rotational speed 21 by a predetermined factor. The output shaft 17 rotates according to the electric motor 16, wherein a direction of rotation can be freely adjustable. In this case, the rotation of the output shaft 17 is proportional to the rotation of the electric motor 16, wherein a transmission ratio represents the proportionality factor. If a transmission is not provided, as illustrated in FIG. 2, the proportionality factor is 1. The arrow from the electric motor 16 to the output shaft 17 indicates the force transfer.

(14) The output shaft 17 penetrates the base 7 of the dishwasher cavity 2 and protrudes into said dishwasher cavity. In this case, the output shaft 17 is sealed, for example, by a shaft sealing ring or the like, so that washing liquor is prevented from escaping. In particular, the output shaft 17 is coupled to a coupling unit 18 that is arranged in the dishwasher cavity 2. The coupling unit 18 comprises in this example an overload protection 19. In the case of a blockage of the spray apparatus 20, the overload protection 18 automatically moves from a coupling state, in which force is transferred between the electric motor 16 and the spray apparatus 20, into a decoupling state in which the transfer of force between the electric motor 16 and the spray apparatus 20 is interrupted. In the coupling state, the overload protection 18 transfers a force from the output shaft 17 to a drive shaft 20A of the spray apparatus 20, as indicated by the arrow.

(15) The spray apparatus 20 is, for example, connected to the drive shaft 20A in a rigid manner and accordingly rotates with said drive shaft. The overload protection is preferably designed in such a manner that the coupling state can be produced in precisely a specific relative position of rotation between the output shaft 17 and the drive shaft 20A. Consequently, in the coupling state, a specific position of rotation of the output shaft 17 corresponds to a specific position of rotation of the drive shaft 20A and thus of the spray apparatus 20.

(16) In embodiments (not illustrated), the drive facility 15 comprises additionally a sensor for detecting a position of rotation of the output shaft 17. The sensor is designed, for example, as a magnetic or optical rotary encoder. It is possible in the coupling state to conclude the position of rotation of the spray apparatus 20 from the detected position of rotation of the output shaft 17. Consequently, the position of the blockage of the spray apparatus 20 is known. On the basis of the known blockage position, it is possible to undertake suitable measures. For example, when an alert is output visually to the user of the dishwasher 1, the blockage position can be represented graphically, so that the user can check the blockage in a simple manner and where appropriate remove it.

(17) FIG. 3 shows two diagrams, wherein the upper diagram shows an angle of rotation of an output shaft 17 (see FIG. 2) and the lower diagram shows a motor rotational speed RPM of an electric motor 16 that is driving the spray apparatus 20 (see FIG. 2). The two diagrams have a common time axis t. The diagrams each illustrate an exemplary course that corresponds, for example, to a dishwasher which has an overload protection 19 (see FIG. 2) in the drive train, as the dishwasher 1 in FIG. 2.

(18) 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 an essentially constant angular velocity. Changes in the motor rotational speed SIG have a proportional effect on the angular velocity of the output shaft 17.

(19) The lower diagram shows the detected motor rotational speed SIG. A closed-loop control adjusts the motor rotational speed SIG to a target value RS for the motor rotational speed SIG. Fluctuations in the motor rotational speed SIG are visible at two points in time t1, t2. These fluctuations occur in the two illustrated rotations of the output shaft 17 respectively in the case of the same angle of rotation of the output shaft 17. The fluctuations are triggered by a coupling/decoupling of the overload protection 19 if the spray apparatus 20 is blocked (see FIG. 1 or 2). If the overload protection 19 is in the coupled state and the spray apparatus 20 is blocked, the drive train is braced until the overload protection 19 is triggered. This causes the motor rotational speed SIG to reduce. If the overload protection is decoupled, the drive train relaxes again and the motor rotational speed SIG increases dramatically again. The electric motor 16 now rotates in a load-free manner, which means that the motor rotational speed SIG can have an increased value temporarily until readjustment by the closed-loop control.

(20) In order to determine in the case of a fluctuation in the rotational speed whether there is a blockage of the spray apparatus 20, two threshold values th1, th2 are illustrated. If one of these threshold values th1, th2 or both threshold values th1, th2 is exceeded, it is possible to conclude a blockage of the spray apparatus 20. The control apparatus 25 (see FIG. 1) is therefore configured, for example, so as to compare the detected motor rotational speed SIG with at least one threshold value th1, th2. In order to reliably detect the blockage, it can be advantageous to wait two or more than two rotations of the output shaft 17 in order to see whether the coupling/decoupling repeats at the same position of rotation of the output shaft 17, as is illustrated in FIG. 3.

(21) Additionally and/or alternatively to comparing the motor rotational speed SIG with threshold values th1, th2, which relate to a target value RS, the control apparatus 25 can be configured so as to determine the local maxima/minima of the motor rotational speed SIG by analysis of the curve (not illustrated). Here, for example, if the first temporal derivative of the motor speed SIG is considered, there would be a zero crossing at each of the local maxima/minima, which can be detected.

(22) FIG. 4 shows a schematic block diagram of an exemplary 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 spray apparatus 20 (see FIG. 1 or 2) driven by means of a drive facility 15 (see FIG. 1 or 2) so as to apply a washing liquor to items to be washed which can be arranged in a dishwasher cavity 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 facility 15 is actuated so as to actively drive the spray apparatus 20. In a second step S2, a motor speed SIG (see FIG. 3) of the electric motor 16 of the drive facility 15 is detected. In a third step S3, a blockage of the spray apparatus 20 is determined in dependence upon the detected motor speed SIG.

(23) In an exemplary embodiment, the method additionally comprises the steps described below. As soon as a blockage of the spray apparatus 20 has been determined, for example as described with reference to FIG. 3, the electric motor 16 is controlled in such a manner that the torque provided is not sufficient to release the overload protection 19 (see FIG. 2). This can be performed, for example, by adjusting a duty cycle to reduce the effective voltage at which the electric motor 16 is operated. When the output shaft 17 has made a complete rotation and the overload protection 19 returns to the coupling state, the torque of the electric motor 16 is not sufficient to decouple the overload protection 19 again. Therefore, the electric motor 16 stops. The angular position of the electric motor 16, which corresponds to the blockage position, is stored. The torque limitation is now removed again and the electric motor 16 is rotated in the other direction. This also drives the spray apparatus 20 in the other direction. The spray apparatus 20 rotates until it impinges against the obstacle from the other side, causing the blockage. The blockage is determined on the basis of the detected motor rotational speed SIG and the torque of the electric motor 16 is again limited in order to determine and store a second blockage position that relates to the other direction of rotation of the spray apparatus Thus, in particular, an angular range in which the spray apparatus 20 is freely rotatable is determined. The spray apparatus 20 can now be swiveled back and forth in the known range.

(24) Although the present invention has been described with reference to exemplary embodiments, it can be modified in numerous ways.