EP2582869A1

EP2582869A1 - Household appliance, in particular a washing machine having a stationary detergent tank

Info

Publication number: EP2582869A1
Application number: EP11724189.3A
Authority: EP
Inventors: Hans Eglmeier; Andreas Hanau; Wilfried Wildung
Original assignee: BSH Bosch und Siemens Hausgeraete GmbH
Current assignee: BSH Hausgeraete GmbH
Priority date: 2010-06-16
Filing date: 2011-06-07
Publication date: 2013-04-24
Anticipated expiration: 2031-06-07
Also published as: CN102939415A; EA023486B1; WO2011157589A1; EA201291423A1; DE102010030163A1; EP2582869B1; PL2582869T3; CN102939415B

Abstract

The invention relates to a household appliance (6) having a rotating component (17) and a drive motor (20) for driving the component (17), said motor comprising a stator (21) having a first magnet arrangement (25) and a rotor (19) coupled to the component (17) and having a second magnet arrangement (24), and having a control device (34) for actuating the drive motor (20), wherein the rotor (19) can be rotated relative to the stator (21) about a rotary axis (S) by the interaction of the magnetic fields generated by the magnet arrangements (24, 25). According to the invention, the magnet arrangements (24, 25) are spaced apart from each other along the rotary axis (S), so that an axial gap (22) is formed between the magnet arrangements (24, 25). The control device (34) is further designed for achieving a coaxial arrangement of the rotor (19) with respect to the stator (21), such that when a distribution of the magnetic field generated by the first and/or the second magnet arrangement (24, 25) is controlled, a constant component of said magnetic field greater than zero is generated. The invention further relates to a method for operating a household appliance (6).

Description

Household appliance, in particular washing machine

with a stationary tub

The invention relates to a household appliance, which has a rotatable component and a drive motor for driving the component, as well as a control device for driving the drive motor. The drive motor comprises a stator with a first magnet arrangement and a rotor coupled with the component with a second magnet arrangement. The rotor is rotatable relative to the stator, namely by interaction of magnetic fields generated by the magnet arrangements. The invention also relates to a method for operating a household appliance.

In the present case, it is preferably a washing machine with a tub firmly connected to a housing. Such a washing machine is known for example from the publication EP 1 433 890 A2. In such a washing machine, the tub can be formed with respect to conventional washing machines enlarged dimensions. The tub is rigidly connected to the housing. In the tub, a laundry drum is rotatably mounted, namely by means of a shaft. The axis of rotation of the laundry drum can be arranged horizontally or slightly inclined in the washing machine. The shaft is coupled to the rotor of a drive motor, the stator of which is held on a support part. The support member closes the tub on a back; It is connected via an elastic seal with the tub. So the laundry drum is supported on the support member, namely by mediation of the shaft.

It is disadvantageous in the subject matter according to document EP 1 433 890 A2 that when the laundry drum is loaded with items of laundry, the laundry drum drops in relation to the tub, so that the distance between the laundry drum and the bottom of the tub decreases. At the same time, the gap between the laundry drum and the upper wall of the tub, as well as a gap between the laundry drum and a door cuff increases. At the beginning of a washing process washing liquor is further supplied to the tub for wetting the laundry items. Part of the liquid supplied is from the laundry items taken, whereby the laundry items by the fluid intake increase in weight and thus further decreases the laundry drum. By rotating the laundry drum loaded with the laundry items, the laundry drum vibrates about its central position, which results from the weight of the laundry items and the liquid absorbed by laundry items. These vibrations can be very large, especially when spinning unevenly distributed laundry items when the laundry drum rotates at a speed near the resonance. So that the laundry drum does not hit the fixed tub in such vibrations, a greater distance between the laundry drum and the tub must be selected as in a conventional system with a so-called mitschwingenden lye containers. Thus, it disadvantageously increases the amount of the so-called "dead liquor", which describes the amount of wash liquor that is not in contact with the laundry items and, in particular, fills the space between the laundry drum and the tub, resulting in increased water and energy consumption. In addition, the laundry items with such a decrease of the laundry drum relative to the tub easier in a larger by the decrease gap between the laundry drum and the door sleeve, which is arranged in the loading opening of the laundry drum, reach and thereby mechanically stressed.

Furthermore, from DE 199 61 780 A1 a household appliance in the form of a washing machine with a drum rotatably arranged in a tub known. This washing machine comprises, for driving the drum, a drive motor which is preferably controlled by a frequency converter and which has a stator with a first magnetic field arrangement and a rotor indirectly coupled to the drum with a second magnetic field arrangement. In the drive motor known from DE 199 61 780 A1, the magnetic field arrangements along the axis of rotation with an axial gap are arranged spaced from each other. It is an object of the invention to provide a comparison with the prior art improved household appliance of the type mentioned. In particular, a domestic appliance is to be created in which the spatial position, in particular in the axial and / or radial direction, of a rotatable component of the household appliance is as simply as possible adjustable or controllable. This object is achieved by a household appliance with the features according to claim 1, as well as by a method having the features of claim 13. Advantageous embodiments of the invention are the subject of the dependent claims and the description.

An inventive household appliance comprises a rotatable component, a drive motor for driving the component, as well as a control device for driving the drive motor. The drive motor has a stator with a first magnet arrangement and a rotor coupled to the component with a second magnet arrangement. By interaction of magnetic fields generated by the magnet assemblies, the rotor is rotatable relative to the stator about an axis of rotation. According to the invention, the magnet arrangements are arranged spaced apart from one another along the rotation axis, so that an axial gap is formed between the magnet arrangements.

Furthermore, the control device is designed to generate a direct component of this magnetic field greater than zero when controlling a distribution of the magnetic field generated by the first and / or second magnetic field arrangement, in particular the magnet arrangement of the stator. In this way, it is possible to achieve a coaxial arrangement of the rotor with respect to the stator or the magnet arrangement to one another during operation of the household appliance. This coaxial arrangement thus arises solely on the basis of the magnetic fields of the magnet arrangements. This may, for example, be such that a predetermined pattern for the energization of the winding of the stator-that is, the rotating field produced-is superimposed with an additional constant magnetic field for all phase strands (offset).

Thus, the effect of the invention is achieved in that the first and the second magnet arrangement are arranged opposite each other in the axial direction side by side and thus form a gap between each other. In contrast to conventional electrical machines, in which the electromagnetic fields or forces act in the radial direction, the electromagnetic fields and forces in the drive motor of the household appliance according to the invention form substantially in the axial direction. Such a drive motor allows a variable and precise adjustment the torque required for the respective size or power level of the household appliance. Namely, such a drive motor offers the advantage that the torque or the power density of the drive motor can be set variably without much effort. Thus, for example, the gap between the magnet arrangements can be formed differently wide; if this gap is very small, a higher torque is transferable than with a larger gap. By such an embodiment of the drive motor, this can also be easily adapted to the available space. Such a drive motor also takes up less space than conventional drive motors and can be optimally adapted to the spatial installation conditions of a variety of household appliances. A significant advantage of the household appliance according to the invention is that a radial movement of the rotor or the stator can be allowed without there being a risk of damage to the drive motor by a stop. It is particularly advantageous that not only the axial gap can be made variable, but on the power density of the drive motor or a variable torque, the position of the rotor of the motor can be influenced in its other spatial directions. Such an axial arrangement of the two magnet arrangements to each other thus also allows an active radial adjustment of the axis of rotation of the rotor relative to the stator, which proves to be particularly advantageous in a washing machine. Namely, by appropriate control of the distribution of the magnetic field of at least one of the magnet arrangements, a coaxial arrangement of the rotor with respect to the stator can be achieved. It can thus set the position of the rotor and / or vibrations or imbalance of the rotatable component active - namely by appropriate control of the distribution of the magnetic fields - are compensated. In particular, in a washing machine can thus be largely or even completely compensate for the decrease of the laundry drum relative to the tub.

The stator and the rotor can be mechanically completely decoupled from each other, so that a lateral movement - ie a movement in the radial direction - of these components against each other is possible. The stator and the rotor thus preferably have a freedom of movement or clearance in the radial direction. The household appliance is preferably a device for the care of laundry items, namely for example a washing machine, a tumble dryer or a washer-dryer. It is preferably a laundry drum of the household appliance, which is driven as a rotatable component by means of the drive motor. Especially in such a household appliance for the care of laundry - especially in a washing machine - proves the embodiment of the drive motor according to the invention is particularly advantageous: The stator can be attached to a housing of the household appliance or on a fixedly connected to the housing tub while the rotor attached to the laundry drum or can be coupled with this. Then, with a sinking of the laundry drum relative to the tub - due to the loading of the laundry drum - again a coaxial arrangement of the rotor with respect to the stator can be achieved, namely by appropriate control of the distribution of the magnetic field - for example by appropriately energizing a winding of the stator. It also manages to balance imbalances of the laundry drum - in particular in a spin operation - by appropriate control of the magnetic field of the stator. Thus, the mechanical stress of bearings of the laundry drum is reduced to a minimum.

As already stated, the household appliance may have a tub firmly connected to a housing. This means that the tub is immobile or immovably connected to the housing and thus can not move relative to the housing. Then, the stator may be disposed on the tub or on the housing. In this way, it is possible to actively adjust the laundry drum against the tub; It can be achieved relative to the tub, the desired position of the laundry drum. The position of the laundry drum can thus be advantageously adjusted independently of the weight of the laundry items to a central position within the tub. As a result, the distance between the washing drum and the tub can be reduced. It thus becomes possible to minimize the amount of "dead liquor", that is, the amount of wash liquor which is not in contact with the laundry.

It proves to be particularly advantageous in terms of a space-saving and weight-reduced drive motor, when the stator and the rotor respectively parallel having mutually arranged discs or annular discs, through which the respective magnet arrangements are held. In particular, when using annular discs, the weight of the drive motor can be reduced to a minimum. The disks or annular disks are preferably arranged concentrically to one another in an unloaded state of the rotatable component. They are preferably mechanically decoupled from each other and have a lateral freedom of movement to each other. The magnet arrangements preferably each have a multiplicity of pole shoes on mutually facing sides. The axial distance between the magnet arrangements may, for example, be in a value range of 1 mm to 100 mm.

The drive motor may be, for example, a brushless DC motor or a permanent magnet synchronous motor. It is preferably the rotor that carries permanent magnets - then the magnet assembly of the rotor includes the permanent magnets. In contrast, the magnet arrangement of the stator can have a winding. This winding can have at least two phase strands, preferably three phase strands. These phase strings can be energized, for example, via an inverter; then the inverter provides one AC voltage for each phase string. The inverter can be electrically coupled to an electrical DC link and provide the respective AC voltages from a DC link voltage. Such a DC link voltage may, for example, be applied to a DC link capacitor. It can be generated from an AC supply voltage - for example the mains voltage - by means of a rectifier. The inverter - and more specifically electrical switch of the inverter - can be controlled by the controller. Thus, the controller may control the frequency and / or the amplitude of the AC voltages. The drive motor can also be designed differently. For example, both magnetic field arrangements of the drive motor may have windings or the magnetic field arrangement of the stator includes the permanent magnets and the magnetic field arrangement of the rotor includes the windings. Hereinafter, only the preferred drive motor will be considered further, wherein the embodiments of the invention are analogously applicable to the other types of the preferred drive motor. The control device can detect at least one electrical measured variable of the drive motor. Preferably, the control device detects such an electrical measured variable which describes an induction taking place in at least one phase strand of the stator. Thus, such a measured variable is preferably detected, which is correlated with an electrical voltage induced in at least one phase strand of the stator by the change in the magnetic flux of the rotor. For example, the control device can detect an electrical voltage as a measured variable which is induced in a phase strand which is currently not actively energized. Additionally or alternatively, the control device in at least one phase strand - preferably in all phase strands - detect an electrical string current. The measurement of such a measured variable has the advantage that the control device can close back to the dynamic movement behavior of the rotatable component. For example, thus an imbalance of the rotatable component can be detected and optionally compensated by the control device, namely by appropriate control of the distribution of the magnetic field of the stator.

The control device can, for example, determine the respectively instantaneous radial and / or axial position of the rotor relative to the stator as a function of measured values for the detected measured variable. In this embodiment, the magnet arrangements of the drive motor are used as sensors for determining the position of the rotor; the drive motor can do without additional position sensors for the determination of the radial and / or axial position of the rotor. If the respective instantaneous position of the rotor relative to the stator is known, the control device can compensate for any deflections of the rotor from a desired position by appropriate control of the distribution of the magnetic field, in particular by appropriate control of the three-phase current in the winding of the stator. Thus, a stable movement behavior of the rotatable component can be achieved.

Depending on measured values for the detected measured variable, the control device may also infer an amplitude and / or a frequency and / or a phase of a deflection of the rotational axis of the rotor with respect to a reference axis. The reference axis is preferably that axis which coincides with the actual axis of rotation when the rotatable component is stationary or, in the case of an unloaded component. The reference axis is thus preferably by the position of the stator established. If the stator comprises a disk or annular disk which carries the magnet arrangement of the stator, then the reference axis can pass through a center or a center of the disk or the annular disk and perpendicular thereto. If the control device determines the amplitude and / or frequency and / or the phase of the deflection of the rotational axis of the rotatable component, it can counteract this deflection, namely by appropriate adjustment of the amplitude and / or the frequency and / or the phase of the rotating field of the stator. In this embodiment, therefore, the determination of an imbalance of the rotatable component takes place; This again turns out to be particularly advantageous in the case of a laundry drum of a domestic appliance for the care of items of laundry. The control device can namely compensate for the unbalance, so that overall a stable movement behavior of the laundry drum and thus also a safe operation of the household appliance can be achieved. Advantageously, therefore, the laundry items located in the laundry drum are mechanically less stressed, and it also increases the life and the life of the household appliance.

It has proved to be particularly advantageous if the control device regulates a distribution of the magnetic field generated by the magnet arrangement of the stator according to a specification, namely as a function of measured values for the detected measured variable - for example as a function of measured values for the induced voltage and / or Measured values for the phase current. By such a regulation, a stable movement behavior of the rotatable component can be achieved overall. The regulation can in fact be such or the specification may include that the amplitude of the deflection of the axis of rotation of the rotor with respect to the reference axis remains below a predetermined limit. It is thus possible, with a vibrating system - such as a laundry drum - to cut a portion of the vibration amplitude. This can reduce the risk of attacks of the system to a minimum. Particularly preferably, the specification for the regulation includes that the axis of rotation of the rotor coincides with the reference axis. Thus, the regulation can be made in view of the fact that the magnet arrangement of the rotor and that of the stator are arranged coaxially with each other. Such a regulation always ensures an optimal position of the rotatable component in the household appliance. Preferably, in the control device, a digital spring and / or damper characteristic for the rotatable component can be predetermined. The control device can then be designed to set the predetermined spring and / or damper characteristic curve for the component by appropriately controlling a distribution of the magnetic field generated by the magnet arrangement of the stator. This embodiment is based on the recognition that the magnet arrangements of the stator on the one hand and the rotor on the other hand form a total of a spring or damper system whose elasticity can be set arbitrarily by the control device. This can in fact be done by a corresponding adjustment of the distribution of the rotating field, so for example by appropriate energization of the winding of the stator. Advantageously, thereby the actual physical spring-damper characteristic of a spring-damper arrangement of the household appliance can be supplemented with the generated by the drive motor virtual spring and / or damper characteristic. Thus, the actual spring-damper characteristic can be adjusted according to the situation and demand, namely, depending on the currently prevailing operating conditions.

In the control device, for example, depending on the amplitude of the deflection of the axis of rotation relative to the reference axis - ie stroke-dependent - spring and / or damper characteristic and / or dependent on a loading of the rotatable component spring and / or damper characteristic and / or one of a Speed of the component dependent spring and / or damper characteristic for the rotatable component can be specified. The stroke-dependent spring and / or damper characteristic may be, for example, a progressive characteristic. A load-dependent spring and / or damper characteristic curve ensures an always optimal suspension and / or damping of the movement of the rotatable component, regardless of the respective instantaneous loading or loading of the component. By means of a speed-dependent spring and / or damper characteristic, the desired spring constant and / or damper constant can each be set for different engine speed values; This is particularly advantageous with regard to a spin operation of washing machines. By using a stroke-dependent - in particular a progressive - characteristic vibration peaks can be avoided, and the risk of a stop of the system can be reduced to a minimum. Overall, therefore, a household appliance is created in which an always stable movement behavior of the rotatable component can be achieved regardless of their load. In particular, in a household appliance for the care of items of laundry, such as a washing machine - especially with a fixed tub - can be achieved by the axial arrangement of the stator and the rotor relative to each other independently of the current load coaxially running system. Namely, the control device can actively influence the dynamic behavior of the household appliance, in particular under the influence of imbalances and changing loads.

In a method according to the invention for operating a household appliance, a rotatable component of the household appliance is driven by a drive motor. A control device controls the drive motor. The drive motor has a stator with a first magnet arrangement and a rotor coupled to the component with a second magnet arrangement. By interaction of magnetic fields generated by the magnet assemblies, the rotor is rotatable relative to the stator about an axis of rotation. The magnet arrangements are arranged spaced apart from one another along the rotation axis, so that an axial gap is formed between the magnet arrangements. Furthermore, to achieve a coaxial arrangement of the rotor with respect to the stator in a control of a distribution of the magnetic field generated by the first and / or second magnet arrangement, a DC component of this magnetic field is generated greater than zero.

The preferred embodiments presented with reference to the household appliance according to the invention and their advantages apply correspondingly to the method according to the invention.

Further features of the invention will become apparent from the claims, the figures and the description of the figures. All the features and feature combinations mentioned above in the description as well as the features and feature combinations mentioned below in the description of the figures and / or shown alone in the figures can be used not only in the respectively indicated combination but also in other combinations or also alone. The invention will now be described with reference to individual preferred embodiments, as well as with reference to the accompanying drawings.

Show it:

Fig. 1A is a schematic representation of a cross section through a drive motor of a washing machine, as known from the prior art;

Fig. 1 B in a schematic representation of an elongated or axial section through the

Drive motor according to FIG. 1A;

2 is a schematic representation of a side view of a household appliance according to an embodiment of the invention;

3A is a schematic representation of an oblong or axial section through a drive motor for a household appliance according to an embodiment of the invention;

3B shows a schematic representation of a cross section through the drive motor according to FIG. 3A,

4A shows a schematic representation of an axial section through the drive motor according to FIG. 3A, wherein a rotor is arranged radially offset with respect to a stator due to a loading of a laundry drum;

4B shows a schematic representation of an end face of the drive motor according to FIG.

4A; and

Fig. 5 in a schematic and highly abstract representation of a household appliance according to an embodiment of the invention.

FIGS. 1A and 1B each show a drive motor 1, as known from the prior art. The drive motor 1 is a brushless DC motor or a permanent magnet synchronous motor. The drive motor 1 comprises a Stator 2, as well as a rotor 3. The stator 2 and the rotor 3 are arranged coaxially with each other, and the rotor 3 is located inside the stator 2 and the stator 2 surrounds the rotor 3. The rotor 3 has permanent magnets 4, the are arranged distributed on a radial outer side of the rotor 3 in the circumferential direction in alternating polarity. The stator 2 has at its radially inner side electromagnets 5, which are formed by a winding with a plurality of phase strands, for example with three phase strands.

If such a drive motor 1 is now used in a washing machine, as is known from the document EP 1 433 890 A2, then there is a problem in that the washing drum of the washing machine can sink relative to a fixed tub. This has disadvantages: it increases the amount of "dead liquor", and there is a risk for the textiles to be treated, as well as mechanical stress on the laundry drum bearings, which can lead to a reduced life and durability of the washing machine.

In Fig. 2, a household appliance 6 is shown according to an embodiment of the invention. The household appliance 6 is a device for the care of laundry. In the exemplary embodiment, the household appliance 6 is a washing machine. It comprises a cuboidal housing 7, in which a passage opening 8 is formed, through which laundry items can be introduced into the household appliance 6. The passage opening 8 can be closed in a conventional manner by means of a door. The household appliance 6 also includes a tub 9, which is fixed or rigidly connected to the housing 7. The tub 9 can thus not move relative to the housing 7. On a rear side 10 of the tub 9 is closed by means of a support member 1 1, which is connected to the tub 9 through the intermediary of an elastic seal 12. The support member 1 1 is connected via a spring assembly 13 with an upper wall 14 of the housing 7; it is supported via a damper assembly 15 on a bottom 16 of the housing 7. The spring assembly 13 may in principle have any number of springs; the damper assembly 15 may comprise any number of dampers, as well as dampers of different types. The position of the spring and damper assembly 13, 15 may vary depending on the design. Likewise, the springs may be integrated in the damper assembly. In the tub 7, a laundry drum 17 is rotatably mounted about a horizontal axis of rotation, wherein in alternative embodiments, the axis of rotation may also be arranged inclined. A shaft 18 fixedly connected to the laundry drum 17 connects the laundry drum 17 to a rotor 19 of a drive motor 20. The drive motor 20 also has a stator 21. The household appliance 6, in the exemplary embodiment, therefore, has a direct drive for the laundry drum 17. The shaft 18 extends through a through hole of the support member 1 1 and is supported on this support member 1 1, namely, for example via a ball bearing.

The laundry drum 17, as well as the rotor 19 are rotatable about a rotation axis S. If the laundry drum 17 is loaded with items of laundry, a force acts on the laundry drum 17 due to the weight of the items of laundry. This force causes a sinking of the laundry drum 17 together with the rotor 19, as well as the support member 1 1. The laundry drum 17 drops from the tub 7, and the rotor 19 moves radially relative to the stator 21st Namely, the rotor 19 and the stator 21 are mechanically decoupled from each other and thus not mechanically centered. The rotation axis S then shifts downward, namely relative to the rotation axis S shown in FIG. 2. In the starting position of the laundry drum 17 shown in FIG. 2 - in which the laundry drum 17 is unloaded - the rotation axis S simultaneously forms a reference axis S '. If the laundry drum 17 is loaded with items of laundry, the position of the axis of rotation S changes relative to the reference axis S '. Alternatively, the spring and damper assemblies 13, 15 may be tuned such that the initial position shown in Fig. 2, i. the coaxial position of the rotor 19 and stator 21, only with an average amount or a household average amount of laundry items loaded laundry drum is achieved. It is advantageous that only in the event of an active control to achieve the coaxial position of the rotor 19 and stator 21 must be made when the amount of laundry items deviates from the average or household standard amount of laundry. Here by the loads of the components can be reduced.

The drive motor 20 is designed such that the rotor 19 and the stator 21 along the axis of rotation S are arranged spaced from each other. This means that between the rotor 19 and the stator 21, an axial air gap 22 is formed. This air gap 22 is free of components. In the starting position of the laundry drum 17 shown in FIG. 2, the stator 21 is arranged parallel to the rotor 19, and a lateral movement of the rotor 19 with respect to the stator 21 is permitted. In such an axial arrangement of the rotor 19 and the stator 21 relative to each other due to the lateral freedom of movement, the risk of a stop or a shock of the rotor 19 against the stator 21 in a deflection of the laundry drum 17 is excluded.

The arrangement of the rotor 19 on the one hand and the stator 21 on the other hand is shown in Fig. 2 only by way of example. Likewise, the stator 21 may be disposed on the fixed tub 9, namely in particular on a radial projection

23 of the tub 9. So the stator 21 may be arranged either on the housing 7 or on the tub 9. The rotor 19 may also be arranged, for example, directly on the laundry drum 17, namely on a rear wall of the laundry drum 17.

The rotor 19 has a magnet arrangement 24, and the stator 21 likewise has a magnet arrangement 25. The magnet assemblies 24, 25 each have axially oriented pole pieces which face each other. So the magnet assemblies 24, 25 face each other. The magnet assembly 24 of the rotor 19 includes a plurality of permanent magnets, which are arranged distributed on a stator 21 facing the end face 26 of the rotor 19 in alternating polarity, namely, for example, along a ring. The magnet assembly 25 of the stator 21, however, comprises a plurality of electromagnets, which are formed by a winding with, for example, three phase strands. The electromagnets are also arranged on a rotor 19 facing the end face 27 of the stator 21. They can also be arranged along a ring.

3A and 3B show an exemplary embodiment of the drive motor 20 including the rotor 19 and the stator 21. As shown in FIGS. 3A and 3B, the rotor 19 and the stator 21 each include an annular disk 28 and 29, respectively the associated magnet arrangement 24 or 25 is arranged. In the unloaded state of the laundry drum 17, the annular discs 28, 29 are arranged coaxially with each other, so that the respective centers of the annular discs 28, 29 are on the reference file S '. If the laundry drum 17 is now loaded with items of laundry, then the laundry drum 17 drops relative to the tub 9, and the axis of rotation S shifts relative to the reference axis S '. Such a scenario is shown in FIGS. 4A and 4B. The rotor 19 and the stator 21 are no longer coaxial with each other and the axis of rotation S is no longer coincident with the reference axis S '. The axial arrangement of the rotor 19 and the stator 21 relative to each other, however, allows an active adjustment of the position of the rotor 19 and thereby the axis of rotation S. Namely, the phase strands of the rotor 21 can be energized simultaneously - namely with a direct current - so that centering forces according to the Arrow depiction P1, P2 arise. By these forces, the rotor 19 is moved back to its original position, so that the axis of rotation S coincides with the reference axis S '. Such a coaxial arrangement of the rotor 19 relative to the stator 21 can also be maintained during the entire operation of the household appliance 6; For this purpose, the rotating field of the magnet assembly 25 of the stator 21 can be superimposed with a DC component (offset), which then ensures the coaxial arrangement.

Referring to Fig. 5, the manner of driving the drive motor 20 will now be explained. In Fig. 5, the household appliance 6 with the laundry drum 17 and the associated rotor 19 is shown. The magnet arrangement 25 of the stator 21 in the exemplary embodiment comprises three phase strings 30, 31, 32 which are electrically coupled to an inverter or inverter 33. Inverter 33 provides an alternating electrical voltage for each phase string 30, 31, 32. The inverter 33 generates these AC voltages by means of suitable switches, in particular by means of transistors. The inverter 33 is driven by a control device 34, which is a microcontroller in the embodiment. The inverter 33 is coupled to an electrical intermediate circuit 35, which has an intermediate circuit capacitor 36. At the DC link capacitor 36 is a DC link _voltage U _z . From this DC link voltage U _z , the inverter 33 generates the AC voltage for the phase strands 30, 31, 32nd

The household appliance 6 has two electrical connections 37, 38, namely a phase connection and a zero connection. The terminals 37, 38 are electrically coupled to a rectifier and line filter 39. The rectifier 39 generates the DC link voltage U _z from an AC supply voltage U _V , which is applied between the terminals 37, 38. The DC link voltage U _z is provided between a circuit node 40 and a reference potential 41. Between the circuit node 40 and the reference potential 41 and the intermediate circuit capacitor 36 is connected. Parallel to the intermediate circuit capacitor 36 is also a voltage divider 42 having a first and a second ohmic resistor 43, 44. A lying between the resistors 43, 44 tap node 45 is connected to a supply terminal of the control device 34. The voltage divider 42 thus divides the DC link voltage U _z , and the controller 34 is supplied with the divided DC voltage.

The inverter 33 - and more particularly its transistors - is coupled on the one hand to the circuit node 40 and on the other hand via three measuring resistors 46, 47, 48 to the reference potential 41. The control device 34 detects phase currents I ₃₀ , I31, I32, which flow through the phase strands 30, 31, 32. For this purpose, the control device 34 is coupled to three nodes 49, 50, 51 which respectively lie between one of the measuring resistors 46, 47, 48 and the inverter 33.

The controller 34 may also detect respective electrical voltages induced in the phase strands 30, 31, 32 due to the magnetic flux of the magnet assembly 24 of the rotor 19. Both the phase currents I ₃₀ , I 31, I 32, as well as the measured induced voltages represent electrical measurement variables of the drive motor 20, which are detected by the control device 34. As already explained, the control device 34 can control the current flow through the phase strands 30, 31, 32 or the distribution of the magnetic field generated by the magnet arrangement 25 of the stator 21 in such a way that a coaxial arrangement of the rotor 19 relative to the stator 21 given is. This may, for example, be such that the control device 34 generates a direct component in the rotating field generated by the phase strands 30, 31, 32, by which means the centering forces are generated.

Depending on measured values for the phase currents I ₃₀ , I31, I 32, and / or depending on measured values for the induced voltages - in particular depending on one in the each current not energized phase strand 30, 31, 32 induced voltage - determines the controller 34, the respective current radial and / or axial position of the rotor 19 relative to the stator 21 and the position of the rotation axis S relative to the reference axis S '. This can be determined by the control device 34 on the basis of the measured values, because the electrical measured variables mentioned depend directly on the extent of induction due to the magnetic flux of the magnet arrangement 24 of the rotor 19.

Thus, the control device 34 determine the respective instantaneous position of the rotor 19 with respect to the stator 21. The control device 34 can thus detect an imbalance of the laundry drum 17. It can be provided that the control device 34 determines an amplitude and / or a phase and / or a frequency of a deflection of the rotation axis S relative to the reference axis S 'as a function of measured values for the above measured variable - such a deflection is for example shown in FIGS 4A and 4B. The control device 34 can then counteract this deflection, namely by appropriate control of the inverter 33.

The control device 34 can also regulate the movement behavior of the laundry drum 17 in dependence on the detected measured values with regard to the fact that the rotation axis S coincides with the reference axis S '. Then, the laundry drum 17 always remains in the optimum position, so that the mechanical components of the household appliance 6 - in particular the storage - can be spared.

The magnet arrangement 24 of the rotor 19 and that of the stator 21 form a total of a spring or damper system. In the exemplary embodiment, the control device 34 also change the elasticity of such a spring and damper system beyond. The elasticity can adjust the control device 34 while changing the rotating field of the magnet arrangement 25 or changing the currents I ₃₀ , I31, I32. In the control device 34-namely, in a memory-characteristic curves can be stored or predetermined in this regard, which make it possible to set different degrees of elasticity of the spring system formed by the rotor 19 and the stator 21. These degrees of elasticity may depend on a current speed of the drive motor 20 and / or in response to a current load of the laundry drum 17 and / or in response to an amplitude of the deflection of the rotation axis S. can be varied with respect to the reference axis S '. Thus, 34 load-dependent and / or speed-dependent and / or stroke-dependent spring and damper characteristics may be predetermined in the control device, according to which the control device 34 controls the rotating field of the magnet assembly 25. The instantaneous elasticity of such a spring and damper system from the rotor 19 and the stator 21 can also be controlled by the control device 34, namely as a function of the detected measured values.

LIST OF REFERENCE NUMBERS

1 drive motor

2 stators

3 rotor

4 permanent magnets

5 electromagnets

6 home appliance

7 housing

8 passage opening

9 tubs

10 back side

11 support part

12 seal

13 spring arrangement

14 upper wall

15 damper assembly

16 floor

17 laundry drum

18 wave

19 rotor

20 drive motor

21 stator

22 air gap

23 advantage

24, 25 magnet arrangements

26, 27 end faces

28, 29 ring washers

30, 31, 32 phase strands

33 inverters

34 control device

35 DC link

36 DC link capacitor 37, 38 connections

39 rectifier

40 circuit nodes

41 reference potential

42 voltage divider

43, 44 Ohmic resistors 45 Tap nodes

46, 47, 48 measuring resistors

49, 50, 51 knots

S rotation axis

S 'reference axis

U _z DC _link voltage U _v AC supply voltage

'30, I31, z string currents

Claims

claims

Domestic appliance (6) with a rotatable component (17) and a drive motor (20) for driving the component (17), which has a stator (21) with a first magnet arrangement (25) and a rotor (19) coupled with the component (17) ) with a second magnet arrangement (24), and with a control device (34) for activating the drive motor (20), wherein by cooperation of the magnet arrangements (24, 25) generated

Magnetic fields of the rotor (19) relative to the stator (21) about a rotation axis (S) is rotatable and along the rotation axis (S), the magnet assemblies (24, 25) are arranged spaced from each other, so that between the

Magnetic arrangements (24, 25) an axial gap (22) is formed, characterized in that for achieving a coaxial arrangement of the rotor (19) relative to the stator (21), the control means (34) is adapted to control the distribution of the Magnetic field generated by the first and / or second magnet arrangement (24, 25) to generate a DC component of this magnetic field greater than zero.

Domestic appliance (6) according to claim 1, characterized in that it is a household appliance (6) for the care of laundry items and the component (17) is a drum (17) for receiving the laundry items.

Domestic appliance (6) according to claim 2, characterized in that it comprises a housing (7) of the household appliance (6) fixedly connected to the tub (9) and the stator (21) on the tub (9) or on the housing (7) is.

Domestic appliance (6) according to one of the preceding claims, characterized in that the stator (21) and the rotor (19) have respective mutually parallel discs or annular discs (28, 29) through which the respective magnet assemblies (24, 25) held are.

5. Household appliance (6) according to one of the preceding claims, characterized in that the magnet arrangement (24) of the rotor (19)

Having permanent magnets and / or the magnet assembly (25) of the stator (21) has a winding, in particular with three phase strands (30, 31, 32).

6. Household appliance (6) according to one of the preceding claims, characterized

characterized in that the control device (34) is adapted to an electrical measured variable (l ₃₀ , l ₃₁ , l ₃₂ ) of the drive motor (20), in particular by at least one phase strand (30, 31, 32) of the stator (21) flowing electrical Phase current (l ₃₀ , l ₃₁ , l ₃₂ ) and / or in at least one phase strand (30, 31, 32) of the stator (21) induced electrical voltage to detect.

7. Household appliance (6) according to claim 6, characterized in that the

Control device (34) is adapted, depending on measured values for the measured variable (l ₃₀ , l ₃ i, l ₃₂ ) on the respective current radial and / or axial position of the rotor (19) relative to the stator (21) to close back ,

8. Household appliance (6) according to claim 6 or 7, characterized in that the control device (34) is adapted to, depending on measured values for the measured variable (l ₃₀ , l ₃ i, l ₃₂ ) to an amplitude and / or a Frequency and / or a phase of a deflection of the axis of rotation (S) of the rotor (19) with respect to a reference axis (S ') to close back.

9. Household appliance (6) according to any one of claims 6 to 8, characterized in that the control device (34) is adapted, in dependence on

Measured values for the measured variable (l ₃₀ , l ₃₁ , l ₃₂ ) a distribution of the by the

Magnetic arrangement (25) of the stator (21) generated magnetic field according to a specification to regulate.

10. Household appliance (6) according to claim 9, characterized in that the specification comprises that the amplitude of a deflection of the axis of rotation (S) of the rotor (19) with respect to a reference axis (S ') below a predetermined limit remains, in particular that the axis of rotation (S) of the rotor (19) with the

Reference axis (S ') coincides.

1 1. Household appliance (6) according to one of the preceding claims, characterized in that in the control device (34) is a digital spring and / or damper characteristic for the rotatable component (17) can be predetermined and the

Control device (34) is designed to by appropriately controlling a

Distribution of the magnetic field generated by the magnet assembly (25) of the stator (21) the predetermined spring and / or damper characteristic for the

Adjust component (17).

12. Household appliance (6) according to claim 1 1, characterized in that in the

Control device (34) dependent on an amplitude of a deflection of the rotation axis (S) with respect to a reference axis (S ') and / or one of a loading of the rotatable component (17) dependent and / or a speed of the component (17) dependent spring - And / or damper characteristic for the rotatable component (17) can be predetermined.

13. A method for operating a household appliance (6), in which a rotatable component (17) by means of a drive motor (20) is driven, which a stator (21) with a first magnet assembly (25) and one with the component (17) coupled Rotor (19) having a second magnet arrangement (24), wherein the drive motor (20) by a control device (34) is driven and by interaction of magnetic fields generated by the magnet assemblies (24, 25), the rotor (19) relative to the stator ( 21) about an axis of rotation (S) is rotated and along the axis of rotation (S) the

Magnetic arrangements (24, 25) are arranged spaced from each other, so that between the magnet assemblies (24, 25) an axial gap (22) is formed, characterized in that to achieve a coaxial arrangement of the rotor (19) relative to the stator (21) in a control of a distribution of the generated by the first and / or second magnet arrangement (24, 25)

Magnetic field, a DC component of this magnetic field is generated greater than zero.