DETERMINING AN IMBALANCE OF A COMPONENT ROTATING AROUND A RADIAL AXIS

Abstract

The invention relates to a method and a device 1 for carrying out the method for determining an imbalance on an object 3 suspended by means of a oscillating movement and having a rotating component 4, wherein the rotating component 4 is driven to rotate at a certain speed by means of an electric motor 14 by supplying a certain current to the electric motor 14, wherein sensors 15, 16, 26 continuously record operating data of the rotating component 4 and supply it to a control unit 20 connected to the sensors 15, 16, 26 for controlling the rotating component 4 according to the operating data, and wherein the control unit 20 determines the imbalance from the operating data.In this method, the sensors 15, 16, and 26 comprise a vibration sensor 26 associated with the object 3 for measuring vibrations of the object 3 in several mutually orthogonal dimensions, a current sensor 15 for measuring the current flowing through the motor 14, and a speed sensor 16 for measuring the speed of the motor 14. Furthermore, the operating data are fed to a correlation unit 21 belonging to the control unit 20. This correlation unit stores learned correlations between imbalances and operating data based on training data measured as operating data for the object 3 at a given imbalance. The imbalance is then determined from the operating data by the correlation unit 21. This method is particularly useful for controlling a spin-drying process in a laundry treatment machine 1.

Description

[0001] The invention relates to a method for determining an imbalance in an object suspended for vibration and comprising a rotating component, wherein the rotating component is driven to rotate at a specific speed by means of an electric motor through which a specific current flows, wherein sensors continuously record operating data of the rotating component and supply this data to a control unit connected to the sensors for controlling the rotating component according to the operating data, and wherein the control unit determines the imbalance from the operating data. The invention also relates to a device for carrying out such a method.

[0002] Document EP 2 379 786 B1 discloses a method of the type defined above, implemented in a laundry treatment machine, wherein the vibratingly suspended object is a tub containing a drum. According to this document, deflections of the tub due to an imbalance in the rotating drum are measured and evaluated with other measured values, in particular the value of the electric current supplied to a motor driving the drum and the drum's rotational speed, to determine the imbalance in the drum. The imbalance that develops at correspondingly high rotational speeds is also to be predicted from early and low rotational speed measurements. For this purpose, a correction function is derived using data on the removal of liquid from the laundry items, from which the imbalance at correspondingly high rotational speed is to be determined.

[0003] Document US 2020 / 0010999 A1 discloses a method for detecting an imbalance error in a laundry treatment machine configured using machine learning, wherein the imbalance error is caused by laundry moving within the machine. Such an identified imbalance error is also used as an indicator for modifying a spin-drying profile in the machine. The current flowing through the motor that drives the drum containing the laundry and the motor's rotational speed serve as measurements for detecting the imbalance error.This imbalance error is detected when the drum rotates so slowly that the laundry items move around each other as the drum turns. It does not correspond to a largely stationary imbalance, such as occurs during spin cycles with rapid drum rotation, where the laundry items are in contact with the inside of the drum. The imbalance error is transmitted via an electronic network to a mobile terminal, which can then display it to a user. The mobile terminal is not intended to control the laundry machine.

[0004] The treatment of laundry in a washing machine regularly includes a spin cycle, and possibly several. During this spin cycle, a large proportion of the washing solution, rinsing solution, or water absorbed by the laundry during the wash or rinse cycle is removed by centrifugation at a sufficiently high speed. This allows the laundry to be completely dried within a reasonably short time by air drying or in a special tumble dryer.

[0005] During the spin cycle, in which laundry items are centrifuged in a rapidly rotating drum, the items are generally not distributed so evenly that the drum, rotating around a predetermined axis, is in equilibrium of forces and moments. Rather, the rapid rotation of the drum with the laundry typically generates forces and moments that cause the drum and the tub in which it is mounted to vibrate, a phenomenon known as "imbalance." Therefore, the tub in the washing machine is suspended by springs and dampers. This dampens the tub's vibrations during the spin cycle, with the dampers converting the vibration energy into heat.At very high spin speeds, with a nearly full drum, or with only a few heavy items of laundry, such damping may not be sufficient. Vibrations transmitted from the drum to the washing machine's housing are also a cause for concern if they become clearly visible or cause additional noise.

[0006] Measures to counteract imbalance include reducing the drum speed during the spin cycle or stopping the spin cycle altogether. However, these measures result in the laundry not being dehumidified to the desired and expected degree. It is therefore advisable to use such measures only to the minimum extent possible.

[0007] The determination of vibrations of a suspended object is carried out in particular by means of a vibration sensor attached to the object or spatially assigned to it, by which these vibrations are measured directly or indirectly, whereby additional data, in particular geometric dimensions and operating data, of the object are also evaluated if necessary.

[0008] There is a need for a method of the type defined above that allows for the most accurate possible determination of the imbalance of a suspended object with minimal material and data processing requirements. It should also be possible to predict the imbalance expected during a centrifugal process.

[0009] When applying the method to the vibratingly suspended tub of a laundry treatment machine, in which a drum that can be filled with laundry items is rotatable, the detection of an imbalance should be possible with the most accurate possible determination of the imbalance, in particular to allow measures against such an imbalance to be taken in a targeted manner and tailored to the size of the imbalance.

[0010] To solve this problem, the invention provides a method with generic features listed at the beginning and in the preamble of the corresponding independent claim, which additionally has the features of the characterizing part of the corresponding independent claim, and a device for carrying out such a method according to the corresponding independent claim.

[0011] Preferred embodiments of the invention are listed in the dependent claims and in the following description and can also be used in combination with one another, insofar as technical considerations permit and even if this is not explicitly stated herein. Preferred embodiments of the method according to the invention correspond to preferred embodiments of the device according to the invention and vice versa, insofar as technical considerations permit and even if this is not explicitly stated herein.

[0012] To solve the problem, the invention accordingly provides a method for determining an imbalance on an object suspended in a vibrational manner and having a rotating component, wherein the rotating component is driven to rotate at a certain speed by means of an electric motor by supplying the electric motor with a certain current, wherein sensors continuously record operating data of the rotating component and supply this data to a control unit connected to the sensors for controlling the rotating component according to the operating data, and wherein the control unit determines the imbalance from the operating data.In this method, the sensors comprise a vibration sensor associated with the object for measuring its vibrations in several mutually orthogonal dimensions, a current sensor for measuring the current flowing through the motor, and a speed sensor for measuring the motor's rotational speed. The operating data is fed to a correlation unit belonging to the control unit. This unit stores learned correlations between imbalances and operating data based on training data measured as operating data for the object at predefined imbalances. The imbalance is then determined from the operating data by the correlation unit. The sensors can also be used to detect other physical quantities that can characterize a vibration, such as force, displacement, strain, or their time derivatives.

[0013] According to the invention, a new method for determining imbalance in a vibratingly suspended object with a rotating component is provided, which allows for the determination of the imbalance with minimal sensor requirements and measures for evaluating the corresponding signals. The use of training data, which empirically includes the correlations between imbalances and operating data, has the advantage that the relationships relevant for measuring the imbalances and the parameters that describe them do not need to be fully known, and that it is also not necessary to limit the imbalance to one present at the time of measurement. Instead, it is possible to determine, i.e., predict, future imbalances.

[0014] There are no special requirements regarding the placement of the vibration sensor, so the sensor can be placed taking into account given spatial conditions and avoiding any impairment of the object's surroundings, while also aiming to generate the largest possible measurement signals.

[0015] To obtain training data, precisely defined imbalances can be created in the rotating component of the suspended object by selectively introducing calibration masses. By observing the corresponding vibrations of the object, the electrical current drawn by the motor, and the rotational speed at which it rotates the component, operating data can be obtained that can then be used to train the correlation unit. Measurements of the operating data without the introduction of calibration masses are also helpful, not least for capturing and accounting for imbalances resulting from asymmetries in the rotating component itself. Training data can, of course, also be generated by directly calculating the operating data as a function of a given imbalance, provided that the parameters describing the oscillating system are known or have been determined.

[0016] The vibrations, current, and rotational speed are measured, in particular, as respective time series of measurements, where the time intervals between two immediately consecutive values ​​are equal to each other and correspond to a fraction of a drum rotation period. From each of these time series, the amplitude and phase of a corresponding rotational frequency component of the drum are determined. At a drum rotational frequency of 1500 revolutions per minute, corresponding to 25 Hz, as is commonly used for centrifugal spinning, such a time interval can be approximately 2.5 milliseconds, thus enabling observation of the vibrations as a function of the drum's rotation angle.In such a case, the drum's rotation period is 40 milliseconds, and therefore a preferred choice for the time intervals appearing in the time series would be a value of 2.5 milliseconds, allowing 16 measurements per drum rotation and thus enabling a correspondingly accurate description of the oscillation of the lye container. These time series can be used directly as input values ​​for the correlation unit within the scope of the invention, thereby avoiding any preliminary work.

[0017] However, it is also conceivable and possible within the scope of the invention to subject the time series to preprocessing, for example to reduce noise effects and thereby increase the accuracy of the imbalance determination. In particular, the time series can be subjected to low-pass or band-pass filtering, optionally supported by the application of a fast Fourier transform.

[0018] In a preferred embodiment of the invention, a regression determined from the training data is implemented in the correlation unit, which determines the imbalance from the operating data. In the context of machine learning, "regression" refers to any model that maps given input variables to a continuous, real number as an output variable, in contrast to "classification," which maps corresponding input variables to discrete classes. A distinction is made between linear methods (linear regression) and nonlinear methods (for example, a neural network) in regression, and both linear and nonlinear methods are possible in this context.

[0019] In a first further preferred embodiment of the invention, the correlation unit is a neural network trained with the training data, in which the regression is implemented.

[0020] In a second, more preferred embodiment of the invention, this regression implemented in the correlation unit is a PLS regression.

[0021] In another preferred embodiment of the invention, the imbalance is determined for a rotational speed greater than the speed measured during the imbalance determination. The invention is thus used to predict an imbalance that will occur under given circumstances, for example, assuming an increase in rotational speed over a predetermined period or assuming a different, particularly higher, rotational speed than the one measured, following the imbalance determination. In particular, the rotational speed for which the imbalance is determined is intended to be achieved in the future within a predetermined rotational speed profile.

[0022] A further advantage is that the imbalance is influenced by the distribution of the filling within the rotating component, whereby the filling distribution can be changed by rotating the component at a speed lower than the fixing speed. In this process, the imbalance determined at a given speed is compared with a first threshold value. If the determined imbalance is greater than the first threshold value, the speed of the rotating component is reduced to a value below the fixing speed for a given time interval and then increased again to the given speed, after which the imbalance is determined again. This case arises particularly when the vibratingly suspended object is a tub in a laundry treatment machine and the rotating component is a drum containing laundry items.When centrifuging laundry items to remove a treatment liquid such as washing liquor, rinsing solution, or water, the drum containing the laundry items is rotated at a speed above the fixing speed, at which point the laundry items press against the inside of the drum and cause an imbalance. If the test shows that this imbalance exceeds the given first threshold value at the speed used for measurement or at a higher speed yet to be achieved, then slowing the rotation below the fixing speed can cause the laundry items to redistribute themselves within the drum, thereby creating a different, and in particular lower, imbalance.

[0023] In a further preferred embodiment of the invention, the rotating component is mounted in a shaft bearing within the object, and the load to which the shaft bearing is subjected by the imbalance is determined. This allows the load on the shaft bearing to be directly determined, making it possible to regulate the rotational speed in such a way as to avoid excessive stress on the shaft bearing.

[0024] In a further preferred embodiment of the invention, the rotating component rotates at a predetermined nominal speed, and the imbalance is determined cyclically. Each instance of imbalance is compared with a second threshold value, and if the imbalance is greater than the second threshold value, the rotational speed of the component is reduced to a lower nominal speed less than the predetermined nominal speed. In a further preferred embodiment, the component then rotates at the lower nominal speed, and each instance of imbalance is compared with the second threshold value. If the imbalance is less than the second threshold value, the rotational speed of the component is increased to a speed greater than the lower nominal speed and less than or equal to the predetermined nominal speed. In this way, it is possible to control the rotational speed as a function of the imbalance determined by cyclic repetition.

[0025] In a further preferred embodiment of the invention, the vibration sensor measures the vibrations in three mutually orthogonal dimensions. This opens up the application of the "3D sensor," which measures vibrations and especially the accelerations caused by them, for the invention.

[0026] According to the invention, a device for carrying out the method according to the invention or one of its embodiments is also provided, comprising a component rotating in a flexibly suspended object, an electric motor for driving the rotating component to rotate at a certain speed by supplying the electric motor with a certain current, as well as sensors for continuously recording operating data of the rotating component and a control device connected to the sensors for controlling the rotating component according to the operating data and for determining the imbalance from the operating data.

[0027] In a preferred embodiment of the invention, the object is suspended in a housing by means of spring struts and damper struts. In a further preferred embodiment, the device is configured as a laundry treatment machine, wherein the object is a tub of lye, and wherein the rotating component is a drum arranged in the tub of lye for receiving a load consisting of laundry items. In a still preferred embodiment, the device is configured to carry out the method for determining the imbalance in a spin cycle, in which a treatment liquid, in particular washing lye, rinsing lye, or water, absorbed by the laundry items is removed by centrifugation.

[0028] In principle, the invention can be applied to any type of laundry treatment machine, especially since the effort required for its application is quite minimal. Besides conventional washing machines, simple spin dryers and washer-dryers are also suitable. The intended orientation of the drum's axis of rotation in space is irrelevant. The axis of rotation can be essentially horizontal, as described in detail below, but it can also be vertical or oriented at any angle to the vertical. The drum is, in particular, cylindrical with a shell extending parallel to the axis of rotation, a rear wall to which a drive shaft is connected at its rear end, and an end plate shaped like a ring at its front end, through which the interior of the drum is accessible for loading and unloading the laundry.

[0029] The system in a laundry treatment machine designed according to the invention, which is oscillating and comprises the tub and the drum, has a resonant frequency, and the highest rotational frequency corresponding to the highest rotational speed is greater than the resonant frequency. This offers advantages with regard to the effective damping of any vibrations. The resonant frequency is determined in particular by the oscillating suspension of the tub on spring struts and damper struts in the housing. At this frequency, the vibrations to be expected due to an imbalance are particularly large. Therefore, it is advantageous to pass through the rotational speed corresponding to the resonant frequency as quickly as possible when accelerating the drum to the desired rotational speed.

[0030] Preferably, the drum rotation is stopped and restarted if the imbalance exceeds a predefined second threshold. Restarting the rotation allows the laundry to redistribute itself, potentially reducing the initial imbalance. An additional advantage is that the drum's rotational speed during the initial imbalance detection is lower than its resonant frequency. This ensures early detection of the imbalance during the spin cycle, minimizing the time lost due to restarting the rotation.

[0031] Exemplary embodiments of the invention are explained in more detail below with reference to the accompanying drawing. The drawing shows: Fig. 1 a sketch of an example of a laundry treatment machine set up according to the invention in side view with a swinging suspended object in which a rotating component is arranged; Fig. 2 a sketch of the same laundry treatment machine in front view; Fig. 3 a diagram showing test results for imbalances determined using the method according to the invention; and Fig. 4 a diagram of a spin-drying process in a laundry treatment machine set up according to the invention.

[0032] The Fig. 1 and Fig. 2 show in two mutually orthogonal sections - Fig. 1 in view in a YZ plane, i.e. from one side, and Fig. Figure 2, viewed in an XY plane, i.e., from the front, is a schematic embodiment of a laundry treatment machine 1, designed as an example of a device for carrying out the method according to the invention. The laundry treatment machine 1 has a housing 2 and, arranged therein, a lye container 3 for receiving a process liquid, in particular washing and rinsing lye for textiles.

[0033] The laundry treatment machine 1 is designed as a washing machine 1. A drum 4, rotatable about a pivot axis 5, is arranged in the tub 3. The pivot axis 5 appears in Fig. 1 as a dot-dash line and in Fig. 2 as X, each surrounded by a curved arrow as a symbol of rotation. The drum 4, containing a process fluid, holds laundry items 6. An approximately cylindrical shell extends from a front end to a rear end of the tub, forming a gap with the drum. The drum is closed near the front end by a substantially annular end plate and near the rear end by a substantially circular back plate. A Fig. A flexible cuff 7, shown in dashed lines, made of a flexible material such as EPDM, seals the tubing 3 to the housing 2 in a liquid-tight manner. A door 8 seals the tubing 3 to the outside in a liquid-tight manner during operation of the laundry treatment machine 1. The drum 4 is driven to rotate via a drive shaft 9, which is guided through the tubing 3 in a sealing manner at a shaft bearing 10, a first pulley 11, a drive belt 12, a second pulley 13, and a motor 14, which is attached to the tubing 3. Systems belonging to the laundry treatment machine 1 for supplying, heating, and discharging process fluids such as water and detergents or rinsing agents are not shown in the figures because they are not essential for describing the method according to the invention.

[0034] Fig. Figure 1 shows a current sensor 15 for measuring the current flowing through the motor 14 and a tachometer sensor 16 for measuring the rotational speed of the motor 14, both schematically represented as lines. There are no specific requirements regarding the design of these sensors 15 and 16, and any suitable known sensor can be used. The current sensor 15 can be an electrical resistor inserted into the line through which the current flows to the motor 14, across which a voltage proportional to the current is measured. The resistor can be integrated into the control unit 20. The tachometer sensor 16 can be a coil located inside the motor 14, in which a voltage is induced whenever the motor 14 rotates the drum 4. This voltage is supplied to the control unit 20 to determine the rotational speed.

[0035] The tub 3 is suspended in the housing 2 by means of spring struts 17 and damper struts 18. Imbalances, which arise particularly from unevenly distributed laundry items 6 in the drum 4 and can be especially large when the drum 4 is rotated particularly fast to dehumidify the laundry items 6 by centrifugation or spinning, lead to vibrations of the tub 3. These vibrations are absorbed by the spring struts 17 and damper struts 18, whereby the energy of these vibrations is converted into frictional heat in the damper struts 18 and released to the environment.

[0036] A 3D sensor 19 is provided to measure vibrations of the washing tub 3 in three mutually orthogonal dimensions, with the measured values ​​being fed back to the control unit 20. In this case, the 3D sensor is mounted on top of the washing tub 3, but this is not a necessary condition. In principle, the 3D sensor can be mounted at any point on the washing tub 3 or even away from it. Preferably, the 3D sensor 19 is mounted at a point where the vibrations of the washing tub 3 are particularly large due to possible imbalances, in order to minimize measurement errors and achieve a particularly good signal-to-noise ratio.

[0037] Determining the vibrations of the tub 3 serves to observe these vibrations and also to influence them. Such influence can be achieved by appropriately affecting the spring and damping properties of the spring struts 17 and damper struts 18, or by controlling, interrupting, and restarting a process in which laundry items 6 are treated by inducing an imbalance, in response to such vibrations.

[0038] The tubing 3 and / or the struts 17 and damper legs 18 may include further sensors (not shown) in the form of strain gauges for detecting vibration-induced deformations of the tubing 3 and / or the forces transmitted via the struts 17 and damper legs 18. Force transducers (not shown) could also be arranged at the mounting points of the struts 17 and damper legs 18 as additional sensors, for example, in the form of measuring washers.

[0039] The control unit 20 serves to control the laundry treatment machine 1, in particular the motor 14 and other systems not shown, and to record and evaluate the above-mentioned measured values.

[0040] In the method for determining an imbalance in an object 3, namely the tub 3, which is suspended on a vibration and has a rotating component 4, namely the drum 4, the rotating component 4 is driven to rotate at a specific speed by means of an electric motor 14 by supplying a specific current to the electric motor 14, wherein sensors 15, 16, 19, namely the current sensor 15, the tachometer sensor 16 and the 3D sensor 19, continuously record operating data of the rotating component 4 and supply this data to the control unit 20 connected to the sensors 15, 16, 19 and / or the control unit 20, which may be connected to the other sensors, for controlling the rotating component 4 according to the operating data, and wherein the control unit 20 determines the imbalance from the operating data.The operating data of the correlation unit 21, in which learned correlations between imbalances and operating data are stored based on training data measured as operating data for object 3 at a given imbalance, are supplied, and the imbalance is determined from the operating data by the correlation unit 21.

[0041] To obtain the training data, precisely defined imbalances can be generated in the rotating component 4 within the suspended object by selectively introducing calibration masses 21 – without any laundry items 6 being added – so that operating data is obtained by observing the corresponding vibrations of the object 3, the electrical current drawn by the motor 14, and the rotational speed at which it rotates the rotating component 4. This data is then used to train the correlation unit 21. Measurements of the operating data without introducing calibration masses 21 are also helpful, not least to detect and account for imbalances resulting from asymmetries in the rotating component 4 itself.Training data can of course also be generated by directly calculating the operating data depending on a given imbalance, provided that the parameters describing the oscillating system 3, 4, 17, 18 are known or could be deduced.

[0042] Correlation unit 21 implements a regression derived from the training data, which determines the imbalance from the operational data. In the context of machine learning, "regression" refers to any model that maps given input variables to a continuous, real number as an output variable, in contrast to "classification," which maps corresponding input variables to discrete classes. Regression is categorized as either linear or nonlinear (e.g., a neural network), and both are relevant here.

[0043] In a first further preferred embodiment of the invention, the correlation unit is a neural network trained with the training data, in which the regression is implemented.

[0044] In a second, more preferred embodiment of the invention, this regression implemented in the correlation unit is a PLS regression.

[0045] Correlation unit 21 is alternatively a neural network trained with the training data in which the regression is implemented, or a PLS regression determined from the training data is implemented in correlation unit 21.

[0046] The described method can not only be used to measure an imbalance present at the time of measurement, but it is also possible to predict an imbalance at a future point in time. This method utilizes the fact that in correlation unit 21, the relationships between operating data and imbalance are only expressed as correlations, not as mathematical functions in the strict sense. Unlike such functions, correlations can also be formed between data that do not apply to a single point in time, provided, of course, that the system's behavior remains constant between the time of measurement and the time at which the determined imbalance applies.With particular advantage, the imbalance is determined for a rotational speed greater than the speed measured during the initial imbalance determination, thus enabling a prediction of the imbalance. A centrifugal process in which such predictions play a role is described below. Fig. 4 explained.

[0047] In the laundry treatment machine 1, the imbalance is influenced by the distribution of the laundry items that form the filling 6 in the rotating component 4. This distribution of the filling 6 can be changed by rotating the component 4 at a speed lower than the fixing speed, at which the filling largely adheres firmly to the inner wall of the rotating component 4. Therefore, the imbalance determined at a given speed is compared with a first threshold value. If the determined imbalance is greater than the first threshold value, the speed of the rotating component 4 is reduced to a value below the fixing speed for a predetermined time interval and then increased again to the predetermined speed, after which the imbalance is determined again.

[0048] In the method, for a shaft bearing 10 in which the rotating component (4) is mounted in the object 3, a load is determined from the determined imbalance to which the shaft bearing 10 is exposed due to the imbalance.

[0049] In particular, during a spin cycle in the laundry treatment machine 1, when the rotating component 4 rotates at a predetermined nominal speed and the imbalance is determined cyclically, each specific imbalance is compared with a second threshold value and, if the imbalance is greater than the second threshold value, the speed of the rotating component 4 is reduced to a lower nominal speed than the predetermined nominal speed. This prevents stress caused by excessively high imbalances.

[0050] When the rotating component 4 rotates at the lower nominal speed, each specific imbalance is compared with the second threshold value. If the imbalance is smaller than the second threshold value, the speed of the rotating component 4 is increased to a speed greater than the lower nominal speed and less than or equal to the specified nominal speed. In this way, the efficiency of the centrifugal process can be increased by checking for and, if necessary, correcting the reduction in speed caused by excessive imbalance.

[0051] The drum 4, which is suspended by spring struts 17 and damper struts 18, has a resonant frequency (or several resonant frequencies) with respect to its vibrations, whereby the highest rotational speed provided for in the process is greater than the resonant frequency. This has advantages with regard to the effective damping of any vibrations. At the resonant frequency, however, the vibrations to be expected due to an imbalance are particularly large. Therefore, it is advantageous to pass through the rotational frequency corresponding to the resonant frequency as quickly as possible when accelerating the drum to the desired rotational speed and also when decelerating after completion of the spinning process.

[0052] Especially at the beginning of a spin cycle, it is advisable to stop and restart the rotation of drum 4 if the load falls below a predefined second threshold. This occurs as soon as the rotational frequency of drum 4 is lower than the resonant frequency when the imbalance is detected. In this way, the imbalance is detected early in the spin cycle, and the time lost due to restarting is minimized.

[0053] The diagram in Fig. Figure 3 shows how precisely the new method described here can determine an imbalance from correlations in training data. The results of tests ("spinning runs") are shown, in which defined imbalances in the drum 4 of a laundry treatment machine 1, set up as described above, were induced by attaching calibration weights 21. The abscissa of the diagram, labeled "imbalance measured," indicates the absolute values ​​of the imbalances calculated or predicted from the correspondingly attached calibration weights, while the ordinate, labeled "imbalance predicted," shows the imbalances determined by the correlation unit 21. Each black circle represents a test.

[0054] As in Fig. As is easily recognizable, the test data are distributed rather closely around the diagonal in the diagram, clearly demonstrating the accuracy of the correlation-based test procedure. Deviations of the test data from this diagonal can be explained, among other things, by the fact that not only the absolute magnitude of an imbalance plays a role in the vibrations of the tub 3, but also the location or distribution of the imbalance along the axis of rotation and, if applicable, the distribution of the imbalance around the axis of rotation 5. There may also be additional influencing factors that the present model does not consider. The distribution of the test data, thus concentrated closely around the diagonal, indicates that the procedure can identify an existing imbalance with only a small error, and therefore represents a particularly suitable basis for predicting and preventing imbalances.

[0055] The diagram in Fig. Figure 4 shows a typical spin-drying process in a suitably configured laundry treatment machine 1. The abscissa of the diagram shows time, the ordinate the rotational speed of the drum 4 with laundry items 6. Also indicated on the ordinate are the rotational speeds below those at which resonances of the oscillating system occur (referred to as "subcritical"), the rotational speeds at which such resonances occur (referred to as "critical range" or "resonance") and the rotational speeds above those at which resonances occur (referred to as "overcritical"), whereby the position of the "resonance" range may need to be determined empirically and also depends on the load of laundry items 6 in the drum 4.

[0056] The in Fig.The spin cycle depicted in Figure 4 begins with the drum 4, containing the laundry items 6, starting at subcritical speeds and accelerating to a speed just below the critical range. Repeated accelerations to a speed just above the critical range can also occur to generate relatively strong vibrations of the tub 3, at least briefly, and thus to determine any imbalance as precisely as possible. If the imbalance determined in this way is too high, the drum 4 can be stopped completely, allowing the process to be restarted in an attempt to achieve a lower imbalance by redistributing the laundry items 6 within the drum.Finally, while the drum's rotational speed alternates between above and below the critical range, a prediction is made for the imbalance expected at the highest speed. Based on this prediction, the spin-drying process is continued by further accelerating drum 4 to the highest speed. This prediction ensures that the imbalance occurring at speeds equal to or slightly below the highest speed does not become so large as to cause damage to the laundry treatment machine 1. By further monitoring the imbalance during the spin-drying process, the rotational speed of drum 4 can be reduced, if necessary, to comply with predefined limits or threshold values ​​for the imbalance.

[0057] Precise knowledge of the imbalance occurring during the spin cycle allows, on the one hand, the components used in the manufacture of the laundry care machine 1 to be adjusted to a maximum imbalance that can be monitored by the method described here, thereby reducing the cost of these components. On the other hand, it also makes it possible for a user of the laundry care machine 1 to individually define threshold values ​​for the imbalance occurring during a spin cycle via a control panel on the laundry care machine 1 or an app implemented on a mobile terminal. This allows the user to take into account unfavorable positioning of the laundry care machine 1, influence its maximum noise level, or its expected energy consumption.Regardless, avoiding unnecessary spin cycles with early stopping and restarting for the purpose of redistributing the laundry items 6 contributes to the user-friendliness of the laundry treatment machine 1 by completing laundry treatment processes more quickly and saving energy by avoiding unnecessary start-ups.

[0058] According to the invention, a new method for determining an imbalance on an oscillatingly suspended object 3 having a rotating component 4 is thus provided, which allows the determination of the imbalance with minimal effort in terms of sensors and measures for evaluating the corresponding signals. Reference symbol list 1 laundry treatment machine 2 cases 3. Swinging suspended object, alkaline container 4 drums 5 axis of rotation 6 fillings, laundry items 7 cuff 8 Door 9 Drive shaft 10 shaft bearings 11 First pulley 12 drive belts 13 Second pulley 14 engine 15 Current sensor 16 Speedometer sensor 17 Shock absorber 18 shock absorber leg 19 3D sensor 20 Control unit 21 correlation units 22 Calibration mass QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] EP 2 379 786 B1

[0002] US 2020 / 0010999 A1

[0003]

Claims

[1] Method for determining an imbalance in an object (3) suspended in a swinging manner and having a rotating component (4), wherein the rotating component (4) is driven by an electric motor (14) to rotate at a specific speed by passing a specific current through the electric motor (14), wherein sensors (15, 16, 19) continuously record operating data of the rotating component (4) and supply said data to a control device (20) connected to the sensors (15, 16, 19) for controlling the rotating component (4) in accordance with the operating data, and wherein the control device (20) determines the imbalance from the operating data, characterized by , that - the sensors (15, 16, 19) comprise a vibration sensor (19) associated with the object (3) for measuring vibrations of the object (3) in several mutually orthogonal dimensions, a current sensor (15) for measuring the current flowing through the motor (14) and a speed sensor (16) for measuring the speed of the motor (14); - the operating data are fed to a correlation unit (21) belonging to the control unit (20), in which learned correlations between unbalances and operating data are stored on the basis of training data which were measured as operating data for the object (3) at a given unbalance, and the unbalance is determined by the correlation unit (21) from the operating data. [2] Method according to claim 1, wherein a regression determined from the training data is implemented in the correlation unit (21), by which the unbalance is determined from the operating data. [3] Method according to claim 2, wherein the correlation unit (21) is a neural network trained with the training data. [4] The method of claim 2, wherein the regression is a PLS regression. [5] Method according to one of the preceding claims, in which the unbalance is determined for a speed which is greater than the speed measured when determining the unbalance. [6] Method according to claim 5, in which the unbalance is influenced by a distribution of a filling (6) in the rotating component (4), wherein the distribution of the filling (6) is variable by rotating the rotating component (4) at a speed which is lower than a fixing speed, in which method the unbalance determined at a predetermined speed is compared with a first threshold value and, if the determined unbalance is greater than the first threshold value, the speed of the rotating component (4) is reduced to a value below the fixing speed for a predetermined time interval and then increased again to the predetermined speed, whereupon a renewed determination of the unbalance takes place. [7] Method according to one of claims 5 and 6, in which the rotating component (4) is mounted in a shaft bearing (10) in the object (3), and in which a load to which the shaft bearing (10) is subjected by the imbalance is determined from the determined imbalance. [8] Method according to one of claims 5 to 7, in which the rotating component (4) rotates at a predetermined nominal speed and in which the determination of the unbalance is carried out cyclically, each determined unbalance being compared with a second threshold value and, if the unbalance is greater than the second threshold value, the speed of the rotating component (4) is reduced to a sub-nominal speed less than the predetermined nominal speed. [9] Method according to claim 8, wherein the rotating component (4) rotates at the sub-rated speed, wherein each determined imbalance is compared with the second threshold value and, if the imbalance is less than the second threshold value, the speed of the rotating component (4) is increased to a speed greater than the sub-rated speed and less than or equal to the predetermined rated speed. [10] Method according to one of the preceding claims, wherein the vibration sensor (19) measures the vibrations in three mutually orthogonal dimensions. [11] Device (1) for carrying out the method according to one of the preceding claims, comprising a component (4) rotating in a vibratingly suspended object (3), an electric motor (14) for driving the rotating component to rotate at a specific speed by passing a specific current through the electric motor (14), as well as sensors (15, 16, 19) for continuously recording operating data of the rotating component (4) and a control device (20) connected to the sensors (15, 16, 26) for controlling the rotating component (4) in accordance with the operating data and for determining the imbalance from the operating data. [12] Device (1) according to claim 11, wherein the object (3) is suspended in a housing (2) by means of spring legs (17) and damper legs (18). [13] Device (1) according to claim 12, which is designed as a laundry treatment machine (1), wherein the object (3) is a tub (3), and wherein the rotating component (4) is a drum (4) arranged in the tub for receiving a filling (6) formed from laundry items. [14] Device (1) according to claim 13, which is designed to carry out the method for determining the imbalance in a spinning process, in which spinning process a treatment liquid, in particular washing liquor, rinsing liquor or water, absorbed by the laundry items is removed by centrifugation.

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