CN111621958B

CN111621958B - Household appliance with ball balancer and fluid viscosity control

Info

Publication number: CN111621958B
Application number: CN202010119546.4A
Authority: CN
Inventors: J·梅尔措; J·钱
Original assignee: BSH Hausgeraete GmbH
Current assignee: BSH Hausgeraete GmbH
Priority date: 2019-02-28
Filing date: 2020-02-26
Publication date: 2023-12-12
Anticipated expiration: 2040-02-26
Also published as: EP3702509B1; PL3702509T3; EP3702509A1; CN111621958A

Abstract

The present disclosure relates to a household appliance (100), in particular to a washing and/or drying machine, comprising: a rotary drum (101) that can be filled with laundry (102); a ball balancer (103) attached around the rotating drum (101), wherein the ball balancer (103) is at least partially filled with a fluid (104) embedding one or more freely moving balancer balls (105) to balance the unbalance of the laundry (102) of the rotating drum (101); a sensor (106) configured to be able to sense a superposition signal (107) resulting from superposition of an unbalance of the laundry (102) and an unbalance of the one or more balancer balls (105); and a controller (108) configured to determine the viscosity of the fluid (104) based on a predetermined correlation of the viscosity of the fluid (104) and the superimposed signal (107).

Description

Household appliance with ball balancer and fluid viscosity control

Technical Field

The present disclosure relates to a household appliance, such as a washing and/or drying machine having a ball balancer and a controller for determining the viscosity of a fluid filled in the ball balancer, and a corresponding method. The present disclosure relates in particular to techniques for determining an actual viscosity by evaluating the period length of an envelope curve of an oscillating signal generated by a household appliance in operation.

Background

Drum washing machine laundry is often unevenly distributed in the drum, especially when wet laundry is embedded in the drum. Therefore, when the drum rotates at a high speed around the horizontal axis, the rotating laundry within the drum is in an unbalanced state. Typically, the rotational speed of the drum has a resonance point between start-up and about 200rpm to 400 rpm. The drum is difficult to use at high rotational speeds due to the vibration, noise and the resulting increase in energy consumption. Accordingly, the conventional drum washing machine includes a rotation control device, also called a ball balancer. If the rotation speed of the drum is higher than the natural frequency of the drum, the balls in the ball balancer move to a relative position with respect to the movement of the laundry in the drum to eliminate unbalance caused by the laundry.

That is, the behavior of the balls in the ball balancer is controlled such that the displacement of the balls with respect to the laundry is arranged at a corrected position, thereby suppressing the drum vibration caused by the unbalanced state.

In addition to the balls, a fluid, such as silicone oil, is sealed and introduced into the ball balancer. This allows preventing collision noise of the balls and stabilizing the ball movements in the ball balancer.

Therefore, optimal control of the washing machine depends on knowledge about the positions of the balls in the ball balancer and the positions of the laundry in the drum.

Disclosure of Invention

An object of the present application is to provide a concept of optimally controlling a home appliance such as a washing machine and/or dryer using the ball balancer as described above.

The foregoing and other objects are achieved by the subject matter of the present application. Further embodiments are apparent from the present application.

The present disclosure is based on the idea that by determining the actual viscosity and/or damping factor (corresponding to temperature) of a fluid (e.g. oil) in a ball balancer, the subsequent rotation period of the respective appliance can be adjusted, so that the appliance can be optimally controlled.

The idea is to determine the viscosity and/or damping of the oil by evaluating the oscillating signal of the oscillating system. These oscillations are caused by the imbalance that always exists in spin-drying. In the specific case of the balancer fixture, the oscillations caused by the laundry unbalance are superimposed by the unbalanced oscillations caused by the rotating balancer balls. For a certain constant subcritical speed, the periodic addition and subtraction of laundry and ball unbalance has a so-called envelope curve in the observed signal (e.g. motor current, speed, displacement, etc.).

This is due to the difference in peripheral speed between the drum speed and the balancer ball speed. The movement of the ball is affected by friction, weight of the ball, damping of oil, etc., and is less than the drum rotation speed. By detecting the minimum and maximum values of the envelope curve, the period length can be calculated. The cycle length thus produced depends on the mechanical properties (filling level, surface of the ring, distance between ball and raceway, etc.), nominal viscosity of the oil at room temperature, temperature behaviour of the oil and actual temperature. All effects on a particular appliance are constant except for temperature, whose behavior can be determined experimentally. The temperature and the corresponding actual viscosity of the oil are thus proportional to the cycle length of the envelope curve and can be calculated by means of a predetermined correlation. Based on this information, important decisions can be made about the subsequent rotation period, e.g. good starting points and gradients can be selected for resonance passage.

The implementation of the above concept provides a novel mechanism and function to achieve controlled resonance pass-through in a ball balancer fixture. Such a function facilitates the spin-drying of small items and reduces the number of spin-drying attempts required. The actual viscosity/damping is necessary as an input to this function. Additionally, a temperature function may be provided which may avoid the necessity of directly measuring the temperature, for example by using an additional sensor.

The appliances and devices described below may be of various types. For example, programmed home or household appliances may include a washer, dryer, combination washer/dryer, drying cabinet, and the like. The individual control elements described may be implemented by hardware or software components, such as electronic components, which may be fabricated by various techniques and include, for example, semiconductor chips, ASICs, microprocessors, digital signal processors, integrated circuits, electro-optical circuits, and/or passive components

According to a first aspect, the present application relates to a household appliance comprising: a rotary drum that can be filled with laundry; a ball balancer attached around the rotating drum, wherein the ball balancer is at least partially filled with a fluid embedding one or more freely moving balancer balls to balance a laundry imbalance of the rotating drum; a sensor configured to sense a superposition signal generated due to unbalance superposition of laundry unbalance and unbalance of the one or more balancer balls; and a controller configured to determine the viscosity of the fluid based on a predetermined correlation of the viscosity of the fluid and the superimposed signal.

Such a household appliance and corresponding controller provide a novel mechanism and function to achieve controlled resonance passage in a ball balancer appliance. The method is convenient for spin-drying small articles, and the required number of spin-drying attempts can be reduced, thereby improving the efficiency of the household appliance.

In an exemplary embodiment of the household appliance, the controller is configured to determine the viscosity of the fluid based on a characteristic oscillation of the superimposed signal.

This provides the advantage that the known correlation of the viscosity of the fluid in the ball balancer with the characteristic oscillations can be exploited to simplify the control of the domestic appliance.

In an exemplary embodiment of the household appliance, the controller is configured to determine the viscosity of the fluid based on an envelope curve of the superimposed signal.

This provides the advantage that the envelope curve of the superimposed signal can be easily determined by tracking the superimposed signal. Accordingly, an efficient control of the home appliance with low computational complexity can be provided.

In an exemplary embodiment of the household appliance, the controller is configured to determine the viscosity of the fluid based on a cycle length of the envelope curve.

This provides the advantage that the period length can be easily calculated from the envelope curve of the superimposed signal. Accordingly, an efficient control of the home appliance with low computational complexity can be provided.

In an exemplary embodiment of the household appliance, the controller is configured to determine the cycle length of the envelope curve based on a detection of a maximum and/or a minimum of the envelope curve.

This provides the advantage that the cycle length of the envelope curve is easy to determine, thereby providing an efficient control of the household appliance.

In an exemplary embodiment of the household appliance, the controller is configured to determine the viscosity of the fluid based on a predetermined proportional relation of the viscosity of the fluid to the period length of the envelope curve.

This provides the advantage that the proportional relation of the viscosity of the fluid to the cycle length of the envelope curve is known and can be stored, for example, in a memory of the household appliance to enable an efficient and low complexity control of the household appliance.

In one exemplary embodiment of the household appliance, the controller is configured to determine the cycle length of the envelope curve based on predetermined mechanical properties of the household appliance, the filling level of the fluid within the ball balancer, the nominal viscosity of the fluid at room temperature, the known temperature behavior of the fluid and the temperature of the fluid.

This provides the advantage that these parameters are known in advance and can be easily provided to the controller.

In an exemplary embodiment of the household appliance, the controller is further configured to determine the temperature of the fluid based on a predetermined correlation of the fluid with the superimposed signal.

This provides the advantage that the fluid temperature can be easily determined by tracking the superimposed signal. Therefore, a temperature sensor is not required, thereby simplifying the design of the home appliance.

In an exemplary embodiment of the household appliance, the controller is configured to determine the temperature of the fluid based on a predetermined proportional relation of the temperature of the fluid to a period length of an envelope curve of the superimposed signal.

This provides the advantage that the period length can be easily calculated from the envelope curve of the superimposed signal. Thus, an efficient detection of the fluid temperature may be provided without the need for expensive temperature sensors.

In an exemplary embodiment of the household appliance, the sensor is configured to sense an electrical drive signal of the rotating drum as a superimposed signal.

This provides the advantage that the electrical drive signal can be sensed effectively, for example by using a current sensor or a voltage sensor or a power sensor. The oscillations of the household appliance are reflected in the electrical drive signal.

In an exemplary embodiment of the household appliance, the controller is configured to control the electric drive signal of the rotating drum based on the determined viscosity of the fluid.

This provides the advantage that optimal control of the drum is possible to reduce or even avoid unbalance conditions at the resonant frequency of the household appliance.

In an exemplary embodiment of the household appliance, the controller is configured to control the rotation period of the rotating drum based on the determined viscosity of the fluid.

This provides the advantage that the number of required spin-drying attempts can be reduced, thereby improving the efficiency of the household appliance. In particular, spin-drying of small laundry may be facilitated.

In an exemplary embodiment of the household appliance, the controller is configured to control the resonance passage of the household appliance based on the determined viscosity of the fluid.

This provides the advantage that resonance passage can be performed with minimal oscillation signal, thereby reducing the energy required and saving the household appliance for mechanical stress situations.

In an exemplary embodiment of the household appliance, the controller is configured to determine the resonance of the household appliance by determining the origin of the rotating drum and the gradient of the electrical signal driving the rotating drum.

This provides the advantage that the household appliance can be controlled to resonate through the system with minimal oscillation, which can reduce the number of spin-drying attempts required and extend the life of the household appliance.

According to a second aspect, the present application relates to a method for controlling a household appliance comprising a rotatable drum fillable with laundry and a ball balancer attached around the rotatable drum, wherein the ball balancer is at least partially filled with a fluid embedding one or more freely moving balancer balls to balance laundry unbalance of the rotatable drum, wherein the method comprises: sensing a superposition signal generated due to superposition of laundry unbalance and unbalance of the one or more balancer balls; determining a viscosity of the fluid based on a predetermined correlation of the viscosity of the fluid and the superimposed signal; and controlling the household appliance based on the determined viscosity of the fluid.

This method for controlling a household appliance provides a novel mechanism and function for achieving controlled resonance passage in a ball balancer appliance. The spin-drying of small items is facilitated and the number of spin-drying attempts required can be reduced, thereby improving the efficiency of the method.

According to a third aspect, the present application relates to a controller for controlling a household appliance comprising a rotatable drum fillable with laundry and a ball balancer attached around the rotatable drum, wherein the ball balancer is at least partially filled with a fluid embedding one or more freely moving balancer balls to balance a laundry imbalance of the rotatable drum, wherein the controller comprises a circuit for receiving a superposition signal from a sensor, the superposition signal being generated as a result of superposition of a laundry imbalance with an imbalance of the one or more balancer balls; circuitry for determining a viscosity of the fluid based on a predetermined correlation of the viscosity of the fluid and the superimposed signal; and a circuit for controlling the household appliance based on the determined viscosity of the fluid.

Such a controller for a household appliance provides a novel mechanism and function to achieve controlled resonance pass through in a ball balancer appliance. The spin-drying of small items is promoted and the number of required spin-drying attempts can be reduced, thereby improving the efficiency of the home appliance.

According to a fourth aspect, the application relates to a computer-readable non-transitory medium having stored thereon computer instructions which, when executed by a computer, cause the computer to perform the method according to the second aspect.

Embodiments of the present application may be implemented in hardware and/or software.

Drawings

Further embodiments of the present application will be described with reference to the following drawings, in which:

fig. 1 shows a schematic view of a home appliance 100 according to the present disclosure;

fig. 2 shows a schematic diagram illustrating an exemplary oscillating signal 200 generated by a household appliance when the household appliance is running;

fig. 3a shows an exemplary dependence of the cycle length of the oscillating signal generated by the household appliance on the temperature for three different rotational speeds of the drum;

fig. 3b shows an exemplary correlation of the cycle length of the oscillating signal with the viscosity of the oil in the ball balancer of the home appliance for three different rotational speeds of the drum; and

fig. 4 shows a schematic diagram illustrating an exemplary method 400 for controlling a home appliance 100 according to the present disclosure.

Detailed Description

In the following detailed description, reference is made to the accompanying drawings, which form a part hereof, and in which is shown by way of illustration specific aspects that may be attributed to the application. It is to be understood that other aspects may be utilized and structural or logical changes may be made without departing from the scope of the present application. The following detailed description is, therefore, not to be taken in a limiting sense, as the scope of the present application is defined by the appended claims.

For example, it will be appreciated that the disclosure relating to the described method may also be true for a corresponding apparatus or system configured to perform the method, and vice versa. For example, if a particular method step is described, the corresponding apparatus may comprise the unit performing the described method step, even if the unit is not explicitly described or illustrated in the figures. Furthermore, it should be understood that features of the various exemplary aspects described herein may be combined with one another, unless specifically indicated otherwise.

A home or household appliance including a ball balancer, such as a washing machine, a dryer, a combination washer/dryer, a drying cabinet, etc., is described below.

Home or household appliances are electrical/mechanical machines that perform some home function, such as cleaning or drying. In view of the wide range of uses, the definition of "home appliance" attached to a home appliance is bundled with "an instrument or device designed for a particular use or function". More specifically, "household appliance" may be defined as: "devices or machines used in your home to do cleaning or drying, etc., are typically electric. Home appliances with ball balancers generally include a washing machine, a dryer, or a combination thereof.

Fig. 1 shows a schematic view of a home appliance 100 according to the present disclosure. The home appliance 100 may be, for example, a washer or dryer or a washer/dryer combination. The home appliance 100 includes a rotary drum 101 that can be filled with laundry 102, a ball balancer 103, a sensor 106, a controller 108, and an electric driver 110. The ball balancer 103 is attached around the rotary drum 101. The ball balancer 103 is at least partially filled with a fluid 104 (e.g., oil) embedding one or more freely moving balancer balls 105 to balance the unbalance of the laundry 102 of the rotary drum 101. The drum 101 may be a cylindrical metal plate in which mechanical grooves or openings for attaching the balls 105 may be formed. The balls 105 may, for example, be included in a ring around the rotating drum 101 that is at least partially filled with a fluid 104 (e.g., oil). The ball balancer may be attached to the top or bottom of the cylindrical rotating drum 101, or attached along the circumference of the cylindrical rotating drum 101.

The sensor 106 is configured to sense a superposition signal 107 generated due to superposition of unbalance of the laundry 102 and unbalance of the one or more balancer balls 105.

The controller 108 is configured to determine the viscosity of the fluid 104 based on a predetermined correlation of the viscosity of the fluid 104 and the superimposed signal 107, e.g. according to the exemplary curve depicted in fig. 3 b.

The controller 108 may determine the viscosity of the fluid 104 based on the characteristic oscillation of the superimposed signal 107 (e.g., the characteristic oscillation 200 shown in fig. 2). The controller 108 may determine the viscosity of the fluid 104 based on an envelope curve (e.g., envelope curve 206 as shown in fig. 2) of the superimposed signal 107. The controller 108 may determine the viscosity of the fluid 104 based on the cycle length of the envelope curve 206 (e.g., the cycle length 205 as shown in fig. 2). The controller 108 may determine the period length 205 of the envelope curve 206, for example, based on detection of the maximum 202 and/or minimum 201 values of the envelope curve 206 as shown in fig. 2.

The controller 108 may be configured to determine the viscosity of the fluid 104 based on a predetermined proportional relationship (e.g., a proportional relationship as shown in fig. 3 b) of the viscosity of the fluid 104 to the period length 205 of the envelope curve 206.

The controller 108 may be configured to determine the cycle length 205 of the envelope curve 206, for example, based on predetermined mechanical properties of the household appliance 100, the fill level of the fluid 104 within the ball balancer 103, the nominal viscosity of the fluid 104 at room temperature, the known temperature behavior of the fluid 104, and the temperature of the fluid 104.

The controller 108 may also be configured to determine the temperature of the fluid 104 based on a predetermined correlation (e.g., a predetermined correlation as shown in fig. 3 a) of the fluid 104 and the superimposed signal 107. The controller 108 may be configured to determine the temperature of the fluid 104 based on a predetermined proportional relationship of the temperature of the fluid 104 to the period length 205 of the envelope curve 206 of the superimposed signal 107, e.g. as shown in fig. 2 and 3 a.

The sensor 106 may be configured to sense the electrical drive signal 111 of the rotating drum 101 as the superimposed signal 107. The electric drive signal 111 may be generated by an electric motor that drives the rotary drum 101. The electrical drive signal 111 comprises an oscillating characteristic as shown in fig. 2 and may be used to detect the period length of the oscillating envelope.

Based on the determined viscosity of the fluid 104, the controller 108 can control the electrical drive signal 111 of the rotating drum 101, for example, so that an optimal control of the household appliance with respect to energy efficiency can be achieved. In particular, the controller 108 may be configured to control the rotation period of the rotating drum 101 based on the determined viscosity of the fluid 104.

The controller 108 may be configured to control the resonant passage of the household appliance 100 based on the determined viscosity of the fluid 104. The controller 108 may determine the origin of the rotating drum 101 and the gradient of the electrical signal 111 driving the rotating drum 101 for resonance of the home appliance 100. This function of the controller may ensure optimal control of the home appliance 100.

The implementation of the above-described home appliance provides a novel mechanism and function to achieve controlled resonance pass-through in a ball balancer appliance. Such a function facilitates the spin-drying of small items and reduces the number of spin-drying attempts required. The actual viscosity/damping is necessary as an input to this function. Furthermore, a temperature function may be provided which may avoid the necessity of directly measuring the temperature, for example by using an additional sensor.

Fig. 2 shows a schematic diagram illustrating an exemplary oscillating signal 200 generated by a household appliance when the household appliance is running. The oscillating signal 200 may be motor current, speed, displacement, etc. The oscillating signal 200 depicted in fig. 2 illustrates a process of how the viscosity and/or damping of the oil is determined. Such an oscillating signal 200 may be caused by an imbalance in rotation that is always present. In the specific case of the balancer fixture as shown in fig. 1, the oscillations caused by the unbalance of the laundry 102 are superimposed by the unbalanced oscillations caused by the rotating balancer balls 105. As shown in fig. 2, for a certain constant subcritical speed, a periodic addition and subtraction of unbalance of the laundry 102 and the ball 105 presents a so-called envelope curve 206 in the observed signal 200. This is due to the difference in peripheral speed between the drum speed and the speed of the balancer balls 105. The movement of the balls 105 is affected by friction, weight of the balls 105, damping of the oil or liquid 104, etc., and is less than the drum rotation speed.

By detecting the minimum 201 and maximum 202 of the envelope curve 206, the period length 205 can be calculated. For example, by tracking the minimum 201 of the oscillating signal 200, e.g. the speed 203, a lower envelope curve may be detected from which the amplitude 204 may be calculated. Alternatively, by tracking the maximum 202 of the oscillating signal 200, an upper envelope curve may be detected from which the amplitude 204 may be calculated. As shown in fig. 2, the temporal distance between two lower (or higher) amplitude values 204 corresponds to a period length 205.

The resulting cycle length 205 depends on the mechanical properties (filling level, ring surface, distance between ball 105 and raceway, etc.), nominal viscosity of the oil or fluid 104 at room temperature, and its temperature behaviour and actual temperature. All effects other than temperature are fixed for a particular appliance, and their behavior can be determined experimentally. Thus, the temperature and the corresponding actual viscosity of the oil or fluid 104 are proportional to the period length 205 of the envelope curve 206 and may be calculated by a predetermined correlation, for example as shown in fig. 3 b. Based on this information, important decisions can be made about the subsequent rotation period, e.g. good starting points and gradients can be selected for resonance passage.

When the equilibrium state is reached, the balls 105 are arranged in the ball balancer 103 at an optimal position, and at this time, the balls 105 are arranged at positions opposite to the unbalanced condition of the laundry 102. Such an equilibrium state is reached at the minimum of the oscillation curve 200 shown in fig. 2, and conversely, at the maximum of the oscillation curve 200, the balancer balls 105 and the laundry 102 are located at the same rotational position, which increases unbalance of the system.

Fig. 3a shows an exemplary dependence of the period length of the oscillating signal generated by the household appliance on the temperature for three different rotational speeds of the drum. The first correlation curve 301 is measured at a speed of 100 revolutions per minute (rpm). The second phase Guan Quxian 302 is measured at a speed of 110rpm and the third correlation curve 303 is measured at a speed of 120 rpm. The time axis represents the period length. For example, at a speed of 120rpm, the third correlation curve 303 indicates that the temperature of 50 ℃ is correlated with a cycle length of 15 seconds. For example, at a speed of 110rpm, the second phase Guan Quxian 302 indicates that a temperature of 50 ℃ is associated with a cycle length of 10 seconds. Thus, determining the period length yields a corresponding temperature when looking up the corresponding correlation curve 301, 302, 303.

Fig. 3b shows an exemplary correlation of the period length of the oscillating signal with the viscosity of the oil in the ball balancer of the home appliance for three different rotational speeds of the drum. The first correlation curve 304 is measured at a speed of 100 revolutions per minute (rpm). The second correlation curve 305 is measured at a speed of 110rpm and the third correlation curve 306 is measured at a speed of 120 rpm. The time axis represents the period length. For example, at a speed of 110rpm, the second phase Guan Quxian 305 indicates that a viscosity of approximately 155 square millimeters per second correlates to a cycle length of 15 seconds, and a viscosity of approximately 95 square millimeters per second correlates to a cycle length of 10 seconds. For example, at a speed of 100rpm, the first correlation curve 304 indicates that a viscosity of about 80 square millimeters per second correlates to a cycle length of about 7.5 seconds. Thus, determining the period length yields a corresponding viscosity when looking up the corresponding correlation curve 304, 305, 306.

In fig. 3a and 3b, the correlation curves are obtained when the fluid 104 or oil fills the ball balancer to a level of 50%.

Fig. 4 shows a schematic diagram illustrating an exemplary method 400 for controlling a home appliance 100 according to the present disclosure. The method 400 may be used to control a home appliance 100 as shown in fig. 1, the home appliance 100 comprising a rotating drum 101 fillable with laundry 102 and a ball balancer 103 attached around the rotating drum 101, wherein the ball balancer 103 is at least partially filled with a fluid 104, such as oil, embedded with one or more freely moving balancer balls 105 to balance the unbalance of the laundry 102 of the rotating drum 101.

The method 400 includes sensing 401 a superposition signal 107 resulting from superposition of an imbalance of the laundry 102 and an imbalance of one or more balancer balls 105.

The method 400 comprises determining 402 the viscosity of the fluid 104 based on a predetermined correlation of the viscosity of the fluid 104 and the superimposed signal 107, e.g. as shown in fig. 3 b.

The method 400 includes controlling 403 the household appliance 100 based on the determined viscosity of the fluid 104, e.g., as described above with reference to fig. 1.

Another aspect of the present disclosure relates to a computer program carrier comprising program code for performing the above-described methods and processes or functions when executed on a computer or processor. The method may be implemented as program code that may be stored on a non-transitory computer medium. The computer program carrier may implement the techniques described above. Another aspect of the disclosure relates to a computer-readable non-transitory medium having stored thereon computer instructions that, when executed by a computer, cause the computer to perform the method 400 as described above.

While a particular feature or aspect of the application may have been disclosed with respect to only one of several implementations or embodiments, such feature or aspect may be combined with one or more other features or aspects of the other implementations or embodiments as may be desired and advantageous for any given or particular application. Furthermore, where the terms "comprising," having, "" with, "or other variations thereof are used in the description or in the claims, these terms are intended to be inclusive in a manner similar to the term" comprising. Furthermore, the terms "exemplary," "e.g.," and "like" merely refer to one example, rather than the best or optimal. The terms "coupled" and "connected," along with their derivatives, may have been used. It should be understood that these terms may have been used to indicate that two elements co-operate or interact with each other regardless of whether they are in direct physical or electrical contact or whether they are not in direct contact with each other.

Although specific aspects have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and/or equivalent implementations may be substituted for the specific aspects shown and described without departing from the scope of the present disclosure. This application is intended to cover any adaptations or variations of the specific aspects discussed herein.

Although elements of the present application are recited below in a particular order, unless otherwise indicated herein, it is not necessarily limited to being implemented in this particular order, unless it implies a particular order for implementing some or all of those elements.

Many alternatives, modifications, and variations will be apparent to those skilled in the art in light of the above teaching. Of course, those skilled in the art will readily recognize that the present application has many applications other than those described herein. While the application has been described with reference to one or more particular embodiments, those skilled in the art will recognize that many changes may be made thereto without departing from the scope of the present application. It is therefore to be understood that within the scope of the appended claims and equivalents thereof, the application may be practiced otherwise than as specifically described herein.

Claims

1. A household appliance (100), comprising:

a rotary drum (101) that can be filled with laundry (102);

a ball balancer (103) attached around the rotating drum (101), wherein the ball balancer (103) is at least partially filled with a fluid (104) embedding one or more freely moving balancer balls (105) to balance the unbalance of the laundry (102) of the rotating drum (101);

a sensor (106) configured to be able to sense a superposition signal (107) resulting from superposition of an unbalance of the laundry (102) and an unbalance of the one or more balancer balls (105); and

a controller (108) configured to determine a viscosity of the fluid (104) based on a predetermined correlation of the viscosity of the fluid (104) and the superimposed signal (107),

wherein the controller (108) is configured to determine the viscosity of the fluid (104) based on the envelope curve (206) of the superimposed signal (107), and

wherein the controller (108) is configured to determine the viscosity of the fluid (104) based on the cycle length (205) of the envelope curve (206).

2. The household appliance (100) as claimed in claim 1,

wherein the controller (108) is configured to determine the viscosity of the fluid (104) based on the characteristic oscillation (200) of the superimposed signal (107).

3. The household appliance (100) as claimed in claim 1,

wherein the controller (108) is configured to determine the period length (205) of the envelope curve (206) based on the detection of the maximum value (202) and/or the minimum value (201) of the envelope curve (206).

4. The household appliance (100) as claimed in claim 1 or 3,

wherein the controller (108) is configured to determine the viscosity of the fluid (104) based on a predetermined proportional relationship of the viscosity of the fluid (104) to the cycle length (205) of the envelope curve (206).

5. The household appliance (100) as claimed in any one of claims 1 to 3,

wherein the controller (108) is configured to be able to determine the cycle length (205) of the envelope curve (206) based on predetermined mechanical properties of the household appliance (100), a filling level of the fluid (104) within the ball balancer (103), a nominal viscosity of the fluid (104) at room temperature, a known temperature behavior of the fluid (104) and a temperature of the fluid (104).

6. The household appliance (100) as claimed in any one of claims 1-3,

wherein the controller (108) is further configured to determine the temperature of the fluid (104) based on a predetermined correlation of the fluid (104) with the superimposed signal (107).

7. The household appliance (100) as claimed in claim 6,

wherein the controller (108) is configured to determine the temperature of the fluid (104) based on a predetermined proportional relationship of the temperature of the fluid (104) and a period length (205) of an envelope curve (206) of the superimposed signal (107).

8. The household appliance (100) as claimed in any one of claims 1-3,

wherein the sensor (106) is configured to be able to sense an electrical drive signal (111) of the rotating drum (101) as a superimposed signal (107).

9. The household appliance (100) as claimed in any one of claims 1-3,

wherein the controller (108) is configured to control the electrical drive signal (111) of the rotating drum (101) based on the determined viscosity of the fluid (104).

10. The household appliance (100) as claimed in any one of claims 1-3,

wherein the controller (108) is configured to control a rotation period of the rotating drum (101) based on the determined viscosity of the fluid (104).

11. The household appliance (100) as claimed in any one of claims 1-3,

wherein the controller (108) is configured to control a resonance passage of the household appliance (100) based on the determined viscosity of the fluid (104).

12. The household appliance (100) as claimed in claim 11,

wherein the controller (108) is configured to determine a start point of the rotating drum (101) and a gradient of an electrical signal driving the rotating drum (101) for resonance passage of the household appliance (100).

13. A method (400) for controlling a household appliance (100), the household appliance (100) comprising a rotatable drum (101) fillable with laundry (102) and a ball balancer (103) attached around the rotatable drum (101), wherein the ball balancer (103) is at least partially filled with a fluid (104) embedding one or more freely moving balancer balls (105) to balance an unbalance of the laundry (102) of the rotatable drum (101), wherein the method (400) comprises:

-sensing (401) a superimposed signal (107) resulting from a superposition of an unbalance of the laundry (102) and an unbalance of the one or more balancer balls (105);

determining (402) a viscosity of the fluid (104) based on a predetermined correlation of the viscosity of the fluid (104) and the superimposed signal (107); and

controlling (403) the household appliance (100) based on the determined viscosity of the fluid (104),

wherein the viscosity of the fluid (107) is determined based on an envelope curve (206) of the superimposed signal (107), and

wherein the viscosity of the fluid (104) is determined based on the cycle length (205) of the envelope curve (206).