WO2013079379A1 - Household washing machine and a method for determining the load quantity of laundry in the laundry drum of a household washing machine - Google Patents

Abstract

The precision of a method for determining the load quantity of laundry in the laundry drum 9 of a household washing machine with an electronic control unit 16 and an electronically controllable drive motor 1 for the laundry drum 9 is to be improved. For this purpose, an action is performed, on the drive motor 1 if applicable, which leads to the generation of mechanical vibrations with a predetermined, in particular a constant, frequency spectrum, which are transmitted to the vibrating unit 11 in which the laundry drum 9 is rotatably mounted. In addition, the frequency spectrum, characterised by absorption, of the secondary vibrations excited in the vibration unit 11 is recorded and is assigned to a load quantity of the laundry drum 9 for which it is typical.

Description

 Household washing machine and a method for determining the loading amount of laundry in the laundry drum of a household washing machine

[0001] The invention relates to a method for determining the loading amount of laundry in the laundry drum of a household washing machine with an electronic control device and an electronically controllable drive motor for the laundry drum, which is rotatably mounted in an oscillating unit about an at least approximately horizontal axis and at the mechanical vibrations are introduced with a predetermined frequency spectrum in the oscillating unit (1 1). Furthermore, the invention relates to a household washing machine, which is set up to carry out the method.

 Several methods are known from the literature in which the behavior of mechanical or electromechanical components can be used to deduce the mass of a laundry drum of a washing machine loaded with laundry. For example, EP 649 930 B1 teaches that during the drum start-up phase for operating the drum at a controlled treatment speed at which the (dry) wash is not held by centrifugal force on the drum shell, the drive torque to the drum drive motor is determined. For this purpose, a measure is required in the program before the actual treatment process, on the one hand takes a certain amount of time and on the other hand is not understood by the user of the washing machine in their benefits. In addition, this method is very imprecise due to imponderable compositions of different laundry items, because the behavior of the drive torque u. a. also depends on the denomination of the laundry item and the specific weight of individual parts.

In another, known from WO 2008/012206 A1 method, the mass of the inserted into the laundry drum dry laundry from the movement of the oscillating aggregate of a washing machine in all three dimensions is calculated in a complicated calculation method, taking into account offset constants. This method also has a limited accuracy; because the so-called offset constants are unfortunately not as constant as they should be. This is mainly because the friction between the mechanical contact points between the springs and the friction dampers on the one hand and the oscillating unit and the housing parts on the other hand and in addition within the friction damper are not at all immutable.

 From DE 197 10 713 A1 discloses a method for determining the degree of filling of introduced in a laundry drum of a washing machine laundry is known. In this method, sound waves, that is to say vibrations of the air, are introduced into the laundry drum in a drum with a sound wave generation unit and the coupled and reflected sound waves are detected by a detector unit. The detector device is provided with an analyzer which determines the intensity and the frequency of the received signals. An evaluation circuit connected to the analyzer determines from the signals the degree of filling of the laundry drum.

 A disadvantage of this method is that only the introduced primary vibrations, which are reflected from the free surface, can be detected, which is why only the degree of filling can be determined. However, the degree of filling of a laundry drum depends on many parameters such as the type of laundry, packing density, etc. Therefore, the degree of filling does not essentially correlate with the loading amount or the loading mass. Somir can be closed with this method only very inaccurate on the load. Furthermore, it is disadvantageous in such a system that additional devices, in particular a sound wave generation unit, are required, which increases the manufacturing costs of a washing machine. The invention has for its object to provide a method for determining the mass of preferably dry laundry items, which is as independent as possible of uncertainties of their parameters to be detected in order to increase the accuracy of the load. Furthermore, this method should be provided inexpensively.

[0007] This object is achieved by a method according to the invention of the type mentioned at the outset using the steps described in claim 1 in such a way that mechanical vibrations, in particular structure-borne sound waves, are introduced into the oscillating unit with a predetermined, in particular constant, frequency spectrum in that the frequency spectrum characterized by absorption is absorbed by the secondary oscillations excited in the oscillating aggregate and assigned to a typical loading amount of the laundry drum. In this method, it is particularly advantageous that the mechanical vibrations introduced into the oscillating unit, the components of the oscillating unit and, above all, the laundry introduced in the laundry drum itself, cause it to vibrate. These excited vibrations are understood as secondary vibrations. These excited vibrations are among others of the mass and the Damping behavior dependent, which is why with this method, the loading amount of laundry is well determined.

This method for finding the appropriate mass of the inserted laundry cost now depends only on how fine is the differentiation of the assignment of the current amount of laundry to typical secondary vibrations. Since you can make a sufficiently accurate differentiation with a simple and inexpensive to install cost of electronic means, the method according to the invention should have a much higher Wiederkehr- accuracy than the known methods.

To generate a constant frequency spectrum, it is particularly advantageous to make a measure according to a development of the invention on the drive motor, which leads to a generation of the predetermined, in particular constant, frequency spectrum of mechanical vibrations that are transmitted to the oscillating unit. Then, no further construction effort is required to generate these mechanical vibrations. In a particularly advantageous manner, according to a development of the method according to the invention such a measure consist in that the drive motor is cyclically cyclically rotated by an amount in the positive direction and then by the same amount in the negative direction. As a result, the drive motor emits mechanical vibrations, in particular in the form of structure-borne noise, which contain a constant frequency spectrum without the need for an additional unit. The same amount is easy to generate; whereas different amounts for both directions of rotation lead to success.

[001] In a particularly advantageous manner, the speed at which the change in the directions of rotation takes place can be in the lower range of the human audible frequency spectrum. A thus audible acoustic annoyance can thus be kept in a safe manageable minimum. With suitable measures and means for generating vibration and for detecting the secondary vibrations, portions of the frequency spectrum or even the entire spectrum of people may contain imperceptible frequencies. Of particular advantage is a development of the method according to the invention, when the secondary frequency spectrum is compared with a catalog of frequency spectra and associated load amounts. In this way, the differentiation of the assignment of the current amount of laundry to typical secondary vibrations is the easiest to and can be taken in any accuracy if the memory for the catalog has a sufficiently large capacity.

Such a measure is to be represented in a simple manner by a further development of the method according to the invention by the frequency spectrum is decomposed into a series of energy peaks at certain frequency locations whose amplitudes are compared with the values stored in the catalog for these frequency locations.

For a household washing machine for carrying out the method according to the invention, it is particularly advantageous if the drive motor is fixed at a position of the oscillating unit, which is suitable for good transmission of structure-borne noise from the drive motor to the oscillating system. For this purpose, it is of particular advantage if the oscillating unit has a component which comes as a membrane for the secondary vibrations in question. Then, namely, the transmission to a suitable sensor can take place most effectively, and the signal to noise ratio is sufficiently large.

 [0015] An acceleration sensor is attached to the component as a sensor for detecting such secondary oscillations on the oscillating unit. Acceleration sensors are common components for household washing machines, which are already being used for tasks similar to the detection of laundry imbalances. An existing acceleration sensor can therefore be used additionally for the new task. Acceleration sensors are also ideal for detecting structure-borne noise.

Further features of the invention are described in the subclaims and in the description of an embodiment. They can be used in any way with each other and with the features of the main claim to further develop the invention advantageous.

[0017] The method according to the invention and a suitable household washing machine are explained below with reference to an embodiment shown in the drawing. In the drawing show

 1 is a schematic representation of a detail of a household washing machine with a control device for a drive motor of the BLCD type, which can transmit its mechanical vibrations to a sensor,

FIG. 2 shows a typical secondary frequency spectrum of a vibrating aggregate containing an empty laundry drum. FIG. Fig. 3 is a secondary frequency spectrum of the same oscillating aggregate, the laundry drum is loaded with a 5 kg laundry items, and

 Fig. 4 is a secondary frequency spectrum of FIG. 3, with a 2 kg heavy

 Loaded laundry items.

The schematically illustrated BLDC motor 1 in Fig. 1 includes a stator 2, in which the windings U, V and W are fixedly connected to the housing 3. Their magnetic fields act on a rotor 4, which consists of a suitable permanent magnet and is freely rotatably mounted in the housing 3 by means of the shaft 5. To control the direction of rotation and the speed of the shaft 5, a BLDC controller 6 is used, which cooperates with a switch array 7, whose switch supplies the windings U, V and W in an order and intensity required for the desired direction of rotation and speed ,

The shaft 5 serves to drive a laundry drum 9, which is rotatably mounted in a tub 8, of a washing machine, not otherwise shown. For this purpose, the engine 1 is attached via a component 10 to the tub 8. Laundry drum 9 and tub 8 are here as well as the drive motor 1 and an unillustrated transmission between the drive motor 1 and the laundry drum 9 to the oscillating unit 1 1. The vibrations of the oscillating unit 1 1 during the rotation of the laundry drum 9 are detected by an acceleration sensor 12 , which passes its signals via the line 13 to a frequency analyzer 14, which signals signals on the analyzed frequencies both to an analog-to-digital converter 15 and to a controller 16. The signals resulting from imbalances of the laundry drum 9 go directly to the control device 16, while the frequency spectrum of higher-frequency signals of the acceleration sensor 12 in the analog-to-digital converter 15 are converted into data sets in a memory 17 shown in the controller 16 there stored records of a catalog, which are assigned to respective load quantities of laundry items. The higher-frequency signals are mainly caused by the propagating in the unit 1 1 structure-borne sound. Such higher-frequency signals are generated in the following manner. In a

Measuring phase for determining the mass of the laundry drum inserted into the laundry 9, the windings U, V, W of the drive motor 1 driven by the switch array 7 by the BLDC controller 6 so impinged with rotational pulses that the drive motor 1 cyclically recurring by an amount in the positive direction and then around it Amount is turned in the negative direction. As a result, so short opposing angular momentum that the engine 1 actually stops but generates mechanical vibrations with an always predetermined, especially constant, spectrum of frequency components, which are transmitted via its housing 3 and the device 10 to the tub 8 of the oscillating unit 1 1 , The mechanical vibrations generated by the engine 1 appear as structure-borne noise. In vibrating unit 1 1 stores the laundry drum 9 with mechanical connection to the tub 8 and therefore resonates with.

The vibrations generated by the drive motor 1 impinge on the empty laundry drum 9, which due to its typical vibration mechanical properties obtains a certain damping to the predetermined, in particular constant, frequency spectrum of the vibrations generated. This attenuation absorbs the generated vibrations to a greater or lesser extent at some or most of the frequency spectrum so that a secondary frequency spectrum shaped by the attenuation of the empty laundry drum 9 is reflected as shown in FIG.

In Fig. 2 it can be seen that the attenuated reflections u7 to u15 at the frequency locations F1 to F9 are still above 50%; the attenuation of the vibrations of the corresponding frequencies are therefore low. Strength damping takes place only at the frequency positions F 10 to F15 (other places were neglected), as the reflections u1 to u6 show. Especially at the higher frequencies, the higher the frequency, the greater the attenuation. A frequency spectrum of the expression according to FIG. 2-as stored in digital form in the catalog of the memory 17-finds the entry "empty" when compared with the catalog.

Now finds a sample instead of a loaded with 5 kg laundry laundry drum 9, then a completely different damping is reflected by the inserted laundry. 3 shows a corresponding secondary frequency spectrum of the reflected oscillations, whose first four frequency positions F1 to F4 show reflections u2 of almost 70%, whereas only frequency reflections u6 to u10 are recorded practically without or with only slight attenuation at the frequency positions F5 to F9 , Only from frequency position F10 - with the exception of the frequency positions F12 and F13 - the attenuation of the reflections u1, u2 and u3 well over 50% and among themselves still quite differentiated. If exactly this frequency spectrum is now stored in the catalog of the memory 17, then the control device 16 reports "loading 5 kg".

Now not all frequencies in the catalog may be stored in absolute accuracy. For this purpose, a certain tolerance is advantageously added for each frequency location. to be left. However, the smaller this permitted tolerance is, the more accurate a load specification can be, but the greater the number of catalog entries with which a secondary frequency spectrum can be compared.

The frequency spectrum according to FIG. 4 is intended to characterize a laundry drum 9 loaded with 2 kg of laundry and shows - also in comparison to those of FIGS. 2 and 3 - no easily recognizable regularity in the deviations of the attenuations of the reflections. Here, the reflection u1 at the frequency location F1 as in FIG. 3 has an attenuation of almost 70%, while the reflection u4 at the adjacent frequency location F2 is only attenuated by approximately 57%. In FIG. 3, this reflection u2 had the same attenuation as on the previous frequency location F1, namely also about 70%. Upon further comparison of the attenuations of the reflections on the comparable frequency locations will be continuous z. T. discover serious deviations that have found their expression in the catalog of the memory 17 and find the assignment to the load quantity "2 kg".

Since the specific frequency spectrums of the respective assigned amounts of laundry are always constant, so neither influenced by unwargetable compositions of different laundry items, the denomination of the Wäschepostens, the specific weight of individual parts of not so constant as desired offset constants is with the inventive method to achieve a significant advance in the accuracy of automatically determined amount of laundry in a washing machine. Of course, other methods for generating and introducing mechanical vibrations with a predetermined, in particular constant, frequency spectrum in the oscillating unit of a washing machine are possible and usable if a vibration source other than the drive motor is available or can be created with little effort ,

Claims

P ate n d p o s p e rc h e Method for determining the loading amount of laundry in a laundry drum (9) of a domestic washing machine with an electronic control device (16) and an electronically controllable drive motor (1) for the laundry drum (9) in an oscillating unit (1 1) by at least approximately horizontal axis is rotatably mounted, are introduced at the mechanical vibrations with a predetermined frequency spectrum in the oscillating unit (1 1), characterized in that the frequency spectrum characterized by absorption of the vibrating unit (1 1) excited secondary vibrations recorded and a typical load for this the laundry drum (9) is assigned. A method according to claim 1, characterized in that the predetermined frequency spectrum is a constant frequency spectrum. A method according to claim 1 or 2, characterized in that the drive motor (1) a measure is taken, which leads to a generation of the predetermined or constant frequency spectrum of mechanical vibrations, which are transmitted to the oscillating unit (1 1). A method according to claim 3, characterized in that the drive motor (1) is rotated as a measure cyclically recurring by an amount in the positive direction and then by the same amount in the negative direction. A method according to claim 4, characterized in that the speed at which the change in the directions of rotation takes place in the lower region of the human audible frequency spectrum. 6. The method according to any one of claims 1 to 5, characterized in that the secondary frequency spectrum is compared with a catalog of frequency spectra and associated load amounts. 7. The method according to claim 6, characterized in that the frequency spectrum is decomposed into a series of energy peaks at certain frequency locations (F1 to F15) whose amplitudes (u1 to 15) are compared with the values stored in the catalog for these frequency locations. 8. Domestic washing machine for carrying out the method according to one of claims 1 to 6 with a laundry drum (9), an electronic control device (16), an electronically controllable drive motor (1) for the laundry drum (9) in an oscillating unit (1 1 ) is rotatably mounted about an at least approximately horizontal axis and a sensor (12) for detecting vibrations, characterized in that the sensor (12) for detecting the frequency spectrum characterized by absorption of the vibrating unit (1 1) excited secondary vibrations is formed, and that the control device (16) comprises a memory with specific frequency spectra stored in the laundry drum (9) and a comparison device with which the frequency spectrum characterized by absorption is comparable to the stored specific frequency spectra. 9. Household washing machine according to claim 8, characterized in that the drive motor (1) at a position of the oscillating unit (1 1) is attached, which is suitable for good transmission of structure-borne noise from the drive motor (1) to the oscillating unit (1 1) , 10. Household washing machine according to claim 8 or 9, characterized in that the oscillating unit (1 1) has a component (10), which comes as a membrane for the secondary vibrations in question. Domestic washing machine according to claim 10, characterized in that for detecting the secondary oscillations of the oscillating unit (1 1) on the component (10) an acceleration sensor (12) is fixed.