CN118480936A

CN118480936A - Method for operating a washing machine and washing machine

Info

Publication number: CN118480936A
Application number: CN202410163361.1A
Authority: CN
Inventors: T·托雷斯; J·坎普斯; P·萨拉佩雷斯; A·维勒加斯; G·桑切斯; U·绍曼
Original assignee: EGO Elektro Geratebau GmbH
Current assignee: EGO Elektro Geratebau GmbH
Priority date: 2023-02-10
Filing date: 2024-02-05
Publication date: 2024-08-13
Also published as: US20240271347A1; EP4414495A1; KR20240125447A

Abstract

In a method for operating a washing machine having a drum, a drive motor for the drum, a power supply for driving the motor, and a washing machine controller for monitoring and detecting motor current by means of the power supply, the following steps are performed, wherein motor current is continuously monitored as the drum rotates for at least three full revolutions. The full revolution of the drum is divided into three rotating sections of equal size, and the motor current is monitored and recorded for each of the rotating sections. An envelope curve of the motor current is calculated, and from this, a standard deviation is calculated. The standard deviation is divided by the mean of the envelope curve to determine the coefficient of variation for each rotation segment. By comparing the determined coefficient of variation for each rotating section with the stored value for the coefficient of variation, the behavior of the laundry item is determined with respect to: whether the laundry items slide down along the drum inner wall, fall from the drum inner wall, or rotate together with the drum. From this behavior, parameters for further operation of the washing machine with respect to the treatment of the laundry items are determined.

Description

Method for operating a washing machine and washing machine

Technical Field

The present invention relates to a method for operating a washing machine, and a washing machine designed to perform the method, wherein the washing machine has a washing machine controller programmed to perform the method.

Background

From the prior art, for example from EP3608466 A1: the motor current of the driving motor for the washing machine is monitored to find out what type of laundry is in the drum. In particular, the type of the fiber of the laundry should be detected.

Another similar method is known from EP2524989B1 and also from EP4008825A1, in which the torque of the drive motor of the drum of the washing machine is monitored to find out how the laundry items behave inside the drum.

Disclosure of Invention

The object of the present invention is to provide a method for operating a washing machine, and a washing machine adapted to perform the method (with which the problems of the prior art can be solved), and in particular to provide a method that allows a safe and reliable detection of the behaviour of laundry items in a drum.

This problem is solved by a method having the features of claim 1 and by a washing machine having the features of claim 19, designed to perform the method. Advantageous and preferred embodiments of the invention are the subject matter of the further claims and will be explained in more detail below. In so doing, some of the features will be explained only for the method or only for the washing machine. However, regardless of this, they can be applied separately and independently of each other to both the method and the washing machine. The terms of the claims are incorporated into the specification by explicit reference.

The method according to the invention relates to operating a washing machine, wherein the washing machine comprises a drum and preferably also a receptacle for rotating the drum therein. A drive motor is provided to rotate the drum in the receptacle, wherein a power source is provided to provide power to the drive motor. As known in the art, this motor current is an indication of the instantaneous power consumed by the motor and converted into mechanical energy. Thus, the motor current is also an indicator of the torque provided by the drive motor. The power supply is also designed to monitor the motor current supplied to the drive motor. The washing machine also has a washing machine controller that monitors and detects motor current from or by means of the power supply. The washing machine controller is preferably a main controller for the whole washing machine, which also has a washing program running and is preferably connected to a user interface or an input/output unit, respectively.

In step a or in general, the drum with the laundry items therein is rotated by means of a drive motor. The laundry items may be previously put into the drum by a user through a conventional door or the like. The motor current is continuously monitored and recorded for further use. In addition, the rotational position of the drum is also monitored and recorded. This is all that is used to know not only the rotational speed of the drum, but also the exact position of the drum, which may be important when considering that laundry items may be quite concentrated in one area within the drum.

In a following step B, one or each of the complete revolutions of the drum during its rotational movement is divided into at least three rotational sections, wherein the motor current is monitored and recorded for each of these rotational sections. In a preferred embodiment of the invention, the rotating sections are preferably of equal size, so that they may be for example 120 °, 90 °, 72 °, etc.

In the next step C, the drum is rotated at a constant rotational speed for at least three full revolutions. This is preferably done in a continuous manner, so that there is no stopping or slowing of the rotational speed, but rather a continuous movement is achieved. As explained previously, each of these complete revolutions is divided into rotating segments. This is all used to make the washing machine controller have a correlation of the rotational position with the motor current and thus the motor torque for each of the rotational sections.

In the next step D, the motor current profile is monitored by the washing machine controller and the envelope profile of the motor current is calculated such that the envelope profile of the motor current for each rotation section and for a complete revolution is known. With the aid of a specific formula known in mathematics, the standard deviation is calculated from the envelope curve to know the standard deviation σ for each rotation section.

In a following step E, the corresponding standard deviation σ is divided by the mean μ of the values of the motor current or envelope curve to determine the coefficient of variation CV for each rotation segment.

In the next step F, the coefficient of variation CV for each rotating section, determined as described previously, is compared with the stored value for the coefficient of variation CV to determine the behaviour of the laundry items in the drum. Such stored values for the CV may be stored in relation to specific parameters of known laundry articles, the most prominent of which is the total weight of the laundry articles in the drum, the kind of laundry articles, or the specific kind of main fibers of the laundry articles, etc. The behavior of the laundry items may be that the laundry items slide down along the drum inner wall during rotation, fall off the drum inner wall, or, in particular, at higher rotational speeds, the laundry items rotate together with the drum while remaining in substantially the same position of the drum inner wall due to centrifugal forces.

In a following step G, after determining the behaviour of the laundry item as described before, specific parameters for further operations of the washing machine with respect to the treatment of the laundry item are determined or derived therefrom. Such parameters may be temperature, duration of the washing process or certain sections of the washing process, rotational speed of the drum, type and amount of additives or detergents used, etc. Of course, additional parameters are available as known in the art.

The present invention serves to ascertain more information about the laundry items in the drum without requiring specific additional and expensive sensors in the washing machine, which additional and expensive sensors also require additional effort in the manufacture of the washing machine or components thereof, respectively. Furthermore, by calculating the envelope curve of the motor current, its standard deviation σ, and the coefficient of variation CV of the motion of the drum with laundry items therein, at least divided into rotating segments as explained before, it is possible to retrieve information about the laundry items and their behaviour, which information is to some extent standardized. This again allows a standardized comparison with the stored values specific to the particular situation, which again allows to ascertain more about the laundry item based on the information only from the motor current and the rotation position of the drum. No additional hardware is required for this that is not yet present in standard washing machines. If the drive motor for the drum is a so-called direct drive (e.g. with respect to the BLDCM motor), information about the rotational position is already included anyway.

In yet another embodiment of the invention, a specific formula for calculating the coefficient of variation CV is used: All this is known from conventional mathematical methods. The preferred formula for calculating the standard deviation σ is: Where x _i is the data point value, μ is the sample average, and N is the sample size.

In a preferred embodiment of the invention, the drum is rotated at a rotational speed of between 30rpm and 90rpm, in particular between 55rpm and 65rpm, for example about 60rpm, for at least three complete revolutions. This particular rotational speed is advantageous because the laundry items can perform well any of the three behaviors described previously, such that they unnecessarily slide down in the drum due to the very low rotational speed, or rotate with the drum due to the relatively high rotational speed. The rotation speed mentioned before should be constant for three revolutions or any number of revolutions so that the external conditions do not change.

In a further embodiment of the invention, steps a to F as described before can be performed two or several times for different rotational speeds in each case where all these steps are performed. Preferably, the rotational speed may be increased after each complete step cycle. If the characteristics are applicable to different rotational speeds, this everything can be used to better retrieve information about the laundry item. It is considered advantageous to increase the rotational speed after performing all steps or each cycle of steps B to F, wherein such increase may be 10% up to 50% or even up to 100%.

In yet another embodiment of the present invention, the method may help to detect whether the laundry items in the drum are distributed sufficiently evenly. For this purpose, a predetermined limit value for the coefficient of variation CV may be used for comparison with the measured value for the coefficient of variation. If the comparison falls below said predetermined limit value, the rotational speed for the drum may thus be changed to redistribute the laundry items in the drum to achieve a more uniform distribution. All this can help to compensate for any unbalance of the laundry items in the drum. In addition to preventing mechanical damage to the washing machine (e.g. excessive wear through any bearings), this all helps to achieve higher rotational speeds, reduce vibration and thus annoying noise.

In a further preferred embodiment of the invention, a number of parameters may be used to detect a sufficiently uniform distribution of laundry items in the drum, the number of parameters being the weight of the laundry items initially determined, preferably in a dry state. Furthermore, the stored value of the coefficient of variation CV for this determined weight for the laundry items and for their behaviour of falling from the drum inner wall is used. Thereafter, steps B to E are performed at least once in order to determine whether the value for the coefficient of variation determined in this way actually corresponds to the stored value. If this is not the case, the rotation speed and/or the rotation direction of the drum is changed, in particular the rotation speed may be reduced, or even the drum may be stopped to achieve redistribution of the laundry items in the drum. After such redistribution (which may also include a change in rotational direction), the same operation is again performed to again compare the determined value with the stored value. The procedure is repeated if they again do not correspond to each other or to a deviation of maximally 10% to 20%. If at any time the values sufficiently correspond to each other, the drum may accelerate to a high speed, for example for spin-drying of laundry items.

In yet another embodiment of the present invention, the following parameters or information may be used to detect whether the laundry items in the drum are sufficiently evenly distributed. These parameters or information include the weight of the laundry items (preferably in their dry state) determined at the beginning of the process. Furthermore, a stored value for the coefficient of variation CV corresponding to this determined weight of the laundry item may be used, preferably also another stored value for the behaviour of the laundry item falling from the inner wall of the drum. Together with using these values, steps B to E as described before are performed to determine whether the value for the coefficient of variation as determined in this way corresponds to a stored value. If this is the case, the drum may be rotated faster to a higher rotational speed, which may be preferably used for spin-drying the laundry items or another purpose. If the values do not sufficiently correspond to each other, a check may be made as to whether the laundry item rotates with the drum. For this purpose, the weight of the laundry item determined at the beginning of the process is used again, as well as the stored value for the coefficient of variation for the determined weight and for the behavior of the laundry item rotating with the drum (which means that the laundry item does not fall down and does not slide along the inner wall). Thereafter, steps B to E are performed again for determining whether the value of the coefficient of variation thus determined corresponds to a stored value for the laundry item corresponding to a behavior of rotating with the drum. If this is the case, the rotation speed for the drum is reduced to check again whether the laundry items still fall off the inner wall of the drum. All this can be used to approximate rotational speeds that are at slightly or significantly higher than the point where the laundry items fall down.

If this is not the case, steps B to E are performed at a constant rotational speed. All this is used to determine whether the determined values for the coefficient of variation CV correspond to stored values for the behavior of the laundry items with respect to their sliding down the drum inner wall. Another distinction can then be made so that if the laundry item does slide downwards, the rotation speed for the drum increases again. Then, it is checked again whether the laundry items still fall off the drum inner wall at a higher rotation speed. On the other hand, if this is not the case, then it is checked as described previously with respect to a sufficiently uniform distribution of laundry items in the drum: whether or not these items still fall off the inner wall of the drum while the rotational speed remains unchanged.

All this serves to better distinguish between the various actions of the laundry items, in particular whether they fall from the inner wall of the drum or whether they slide downwards.

It may also be provided that the treatment of the laundry items is further performed if the distribution of the laundry items is considered to be sufficiently uniform. In this case, the spin-drying process may preferably be performed because high rotational speeds are used for spin-drying, and for these high rotational speeds, a uniform distribution is advantageous or even necessary to avoid vibrations as described herein.

In a further embodiment of the invention, it is possible to monitor the wetting or wetting of the laundry items in the drum with water. All this can be used to detect whether the laundry items are sufficiently uniformly wetted in the drum. First, the weight of the laundry item may be determined at the beginning of the process. The stored value for the coefficient of variation CV for this determined weight for the laundry items is then used, which stored value is also characteristic of the behaviour of the laundry items, in which case they rotate together with the drum so that they do not fall or slide downwards. Thereafter, the laundry items are wetted by introducing water into the drum or onto the laundry items, preferably by spraying. Steps B to E as described before are then performed, which serve to determine whether the value for the coefficient of variation determined in this way corresponds to a stored value for the behavior of the laundry item rotating with the drum. If this is the case, the rotation speed of the drum is increased to a higher speed, which may be used for example in a spin-drying process of laundry items. If this is not the case, the rotation speed and/or the rotation direction of the drum is changed, which serves to redistribute the laundry items again to allow a higher rotation speed without vibration.

In a further refinement of the invention, it is checked at a constant rotation speed whether the laundry item falls off the drum inner wall, based on the previously described case in which the determined value for the coefficient of variation does not correspond to the stored value for the behavior of the laundry item rotating with the drum. Such checks may be performed as initially described. The initially determined weight of the laundry item and the stored value for the determined weight of the laundry item and for the coefficient of variation of the behavior of the laundry item falling from the inner wall of the drum are then used for this purpose. Thereafter, steps B to E are performed again in order to determine whether the value for the coefficient of variation determined in this way corresponds to a stored value for the behaviour of the laundry item falling from the inner wall of the drum. If this is the case, the drum rotates faster and then checks again to see if the laundry item is still rotating with the drum at a higher rotational speed. If this is not the case, steps B to E are performed again at a constant rotational speed. All this is used to determine whether the determined value for the coefficient of variation corresponds to a stored value for the behavior of the laundry item sliding down the inner wall of the drum. Again, if this is the case, the drum rotates at a higher rotational speed and then a check is made to see if the laundry items still slide down the drum inner wall at this higher rotational speed. If this is not the case, a check is made to see if the laundry items are still rotating with the drum at the same rotation speed, according to what has been described previously for detecting laundry items of sufficiently uniform distribution.

In yet another embodiment of the present invention, the washing process of laundry items in the drum with water is monitored. All this can be used to determine the appropriate washing process for the particular laundry item detected in the drum. In this case, the weight of the laundry item determined at the beginning of use is used, as well as the stored value for the determined weight for the laundry item and the coefficient of variation CV of the behaviour of the laundry item desired for the particular washing process. Thereafter, steps B to E are performed again to determine whether the value for the coefficient of variation determined in this way corresponds to a stored value for the desired behavior of the laundry item. If this is the case, the drum is rotated further at the same rotational speed and in the same direction for the next washing cycle. However, if this is not the case, the rotational speed and/or rotational direction of the drum is changed. This all can be used to better redistribute the laundry items in the drum.

In a further possible embodiment of the invention, the quantity or weight of the laundry items, in particular in the drum in the dry state of the laundry items, is always determined at the beginning of the operation of the washing machine or before the beginning of the washing process. All this can be done by weighing the laundry items with a physical load cell. All of which are well known to those skilled in the art. Alternatively, the motor current may be monitored as the drum rotates with the laundry items therein. All this is also known in the art and such methods do not require any specific additional load cells or the like.

In general, the method can be used to find an optimal rotational speed for wetting or wetting laundry items or for spin-drying, especially at the end of a washing process.

In addition to the standard deviation and the average deviation, it is also possible to use a coefficient of variation as described previously. This all allows more choices and a more accurate process.

These and further features are evident not only from the claims but also from the description and the drawing, the individual features are implemented by themselves or in several times in the form of sub-combinations for use in the embodiments of the application and in different fields and can be advantageous and individually protectable embodiments, to which protection is claimed here. The division of the application into individual segments and subheadings does not limit the overall effectiveness of the statements made below.

Drawings

Exemplary embodiments of the present invention are schematically shown in the drawings and will be explained in more detail below. The drawings show:

figure 1 is a schematic front view onto a washing machine according to the present invention having laundry items therein,

Figure 2 is a schematic view of the forces acting on an item of clothing in the drum of the washing machine of figure 1,

Figure 3 is a block diagram of a load redistribution algorithm,

Figure 4 is a block diagram of a load wetting algorithm,

Figure 5 is a block diagram of an improved washing algorithm,

Figure 6 is a motor current of a driving motor of the washing machine and an envelope of the motor current,

Fig. 7 is a schematic view of an article of clothing having a falling, true sliding movement with respect to the movement of the paddle, and a table of coefficients of variation for both movements,

Fig. 8 is the two motions of fig. 7, with motor current envelopes for three and two turns respectively,

Fig. 9 is a schematic view of a drop off, not with respect to blade movement, and a corresponding table of coefficients of variation,

Figure 10 is a motor current envelope for the motion of figure 9,

Fig. 11 is a schematic view of the rotation of the laundry item together with the drum, and a corresponding table of the variation coefficients for this movement,

Figure 12 is a motor current envelope for the motion of figure 11,

Fig. 13 is a comparison of the various coefficients of variation for three turns for a drop in blade motion, with each turn divided into three thirds.

Detailed Description

A schematic view of a washing machine 11 according to the present invention can be obtained from fig. 1. The washing machine 11 has a housing 12, wherein a rotary drum 14 in the housing 12 is placed in a fixed drum receiving portion 13 surrounding it. As is common in the art, the rollers 14 are rotated or driven by a drive motor 16 having a drive belt 17, respectively. On the inner side of the drum 14, three paddles 19 forming well-known protrusions are provided in the form of ribs or in the form of triangles with rounded ends directed towards the inner side of the drum 14. The blades 19 are shown in outline and may preferably have this form in a direction parallel to the axis of rotation of the drum 14. The blade 19 is advantageous for a normal washing process, but is not absolutely necessary for the current invention.

Inside the drum 14, a number of laundry items 30 are shown being rotated and thrown. This will be described in detail later. Which corresponds to a normal process of rotating the drum at a relatively low speed.

The drive motor 16 is driven or energized by a power control unit 32, the power control unit 32 again being controlled by a washing machine controller 34, the washing machine controller 34 preferably being the main controller of the entire washing machine 11. The washing machine controller 34 is connected to a current sensor 35, which is capable of accurately supervising the driving current supplied to the driving motor 16 by the power control unit 32. Such current sensors 35 are known in the art and can be provided without problems by a person skilled in the art. It may also be integrated into the power control unit 32 or into the drive motor 16 itself.

Integrated into the drive motor 16 may be a rotational position sensor device for supervising or detecting the rotational position of the drum, which is not shown here due to the integration. As is also common in the art, such rotational position sensor devices may be integrated into the drive motor 16, preferably as an incremental encoder. The rotational position sensor device is also connected to a central washing machine controller 34. The washing machine controller 34 is also provided with a reservoir 37 as mentioned before and as will be explained in detail below, which is preferably integrated into one of the semiconductor components.

In fig. 2, drum 14 is shown with laundry items 30 therein for a better basic understanding of the present invention. Indeed, of course, a plurality of laundry items will be in the drum 14. The center of gravity or centroid of the article of clothing 30 is at an angle α to the vertical axis as indicated by the dashed line. Due to the rotation of the drum 14, the laundry item 30 abuts against the inside of the drum 14. Gravity F _GR is directed vertically downward. Centrifugal force F _CE generated by the rotation of drum 14 and depending on its rotational speed, is directed outward in a radial direction away from the center of drum 14 and through the center of gravity of laundry item 30. The friction force F _FR is directed upwards in the circumferential direction or in the tangential direction, respectively, from the area of the laundry item 30 in contact with the inner side of the drum 14, which is also at right angles to the centrifugal force F _CE. The sliding force F _SL is directed in the opposite direction of the friction force F _FR. If the laundry item 30 does not abut against the paddle 19, the laundry item 30 moves counter-clockwise with the rotating drum 14 by the friction force F _FR. The sliding force F _SL again pulls the clothing item 30 downward, initiated by gravity F _GR. When the fabric or fiber of the article of clothing 30 has a small coefficient of friction and/or the article of clothing 30 is lightweight (possibly because it does not absorb too much water), then there is not enough friction force F _FR. As a result, the laundry item 30 slides down only on the inside of the drum 14, most likely also up the paddle 19. If a certain rotational speed is exceeded, the laundry item 30 will be pressed against the inside of the drum 14 by the centrifugal force F _CE and will not move relative to the drum 14, but will rotate therewith and at exactly the same rotational speed.

In the state when the laundry item 30 is pressed against the inner wall of the drum 14 and thus precisely rotates together with the drum 14, any variation in the rotational speed of the drum means a variation in the kinetic energy of the system of combined drum 14 and laundry item 30. The greater the weight the combined system has, the greater the kinetic energy that must be provided by the drive motor 16. If only a relatively small number of laundry items 30 are inside the drum 14, the energy or instantaneous power required to drive the motor 16 to accelerate the drum from the first low rotational speed to the second high rotational speed is significantly less than when a relatively large number of laundry items 30 are inside the drum 14. This difference in the required energy or power, respectively, from the drive motor 16 may be detected and may be stored in particular in a reservoir 37 connected to the washing machine controller 34. If in practice the washing machine 11 is now loaded with an unknown quantity of laundry, all this is according to the invention required for detecting this higher rotation speed power or energy requirement and can be compared with the stored value of power or energy stored in the reservoir 37. In the present invention, it is provided that these values relating to the power or energy are not stored directly, but rather to the current minimum, current maximum and average current.

In fig. 3, an exemplary method for redistributing laundry items in a drum is shown. The algorithm may be specifically selected by the user or by the washing program, if desired. First, the amount of the laundry item or load, respectively, is selected. Preferably, this value is detected in any way at the beginning of each washing or laundry treatment process, wherein the advantage is that the laundry item is dry at this time.

In a next step, a corresponding coefficient of variation is selected that is related to the load and to the behavior of the laundry item falling from the inner wall of the drum. In the next step, steps B to F as described previously are performed to ascertain whether such a falling motion is detected. If it is detected, the clothing item needs to rotate faster to find the unbalanced speed. If such a falling motion is not detected, there are two possibilities that the behavior of the laundry item may have. Next, it is detected whether the laundry item rotates with the drum, so that the values determined in steps B to F are compared with the appropriate coefficient of variation of such a rotary motion. If this is the case, the drum decelerates to allow the laundry items to fall downward and not rotate with the drum. If no rotational movement is detected, a corresponding coefficient of variation is employed for the detected amount of load related to the sliding movement of the laundry item. If the correlation between them is suitable, a sliding movement of the laundry item is detected, but this sliding movement is not supposed. As a result, the rotation speed of the drum increases again. If no sliding movement is detected either, the rotational speed remains constant and starts again to try to detect such a falling movement. Alternatively, an error may be output, or as yet another alternative, an attempt is made to use this everything as a case of a falling motion. As yet another alternative, the drum may be stopped and the entire procedure may be started again to generate new values from performing steps B to F.

In fig. 4, a load wetting algorithm is described, the purpose of which is that wet laundry should be rotated together with the drum. At the beginning, the value of the load in the dry state is again required. This may be done as described previously.

In the next step, a coefficient of variation CV for the rotational movement of the laundry item is selected corresponding to the load amount. In the next step it is checked whether the wetting phase has already started, which means that water is brought into the drum or directly onto the laundry item, respectively. If this is the case, steps B to F are performed again. First, it is checked whether a rotational movement of the laundry item is detected. If this is the case, the rotational speed remains constant. Preferably, more water can be brought onto the laundry item, so that during this wetting phase it is checked again whether there is still a rotational movement. However, if no rotational movement is detected, it is checked whether a falling movement can be detected. This may be done as described previously. If such a falling movement of the laundry item is detected, which means that the rotational speed is too low, the rotational speed is slightly increased, for example by 10% to 30% or even 100%. After the addition, it is checked again what type of movement of the laundry item is to be found using the procedure according to steps B to F.

If neither rotational nor falling motion is detected, it is checked whether sliding motion can be detected. Typically, the rotational speed for the sliding movement is lower than the rotational speed for the falling movement. If this is the case, the rotational speed also increases, preferably even more than in the case of the previously described falling motion. This also serves to achieve a rotational movement of the article of clothing. If sliding movement is not yet detectable, steps B to F are performed again in an attempt to detect which type of movement is present.

In fig. 5, another algorithm for improving washing is shown. As described previously, the amount of load needs to be known at the beginning. After this, a coefficient of variation corresponding to the load and any motion required by the washing algorithm is selected. The any movement may be any of the three movements previously described.

Next, steps B to F are performed to ascertain whether the required movements are detected or whether their coefficients of variation sufficiently correspond to each other. If this is the case, the rotational speed may be kept constant to continue in the same manner or process during the washing process. If this is not the case, the rotational speed or even the rotational direction may be changed as described before.

In fig. 6, a typical curve of the motor current I over time is shown in thin lines. The envelope curve of the motor current I is shown in bold. This envelope curve is used for the algorithms and formulas described herein because it can be used much better and more easily.

In fig. 7, the movement of the laundry item with five positions is shown, which corresponds to the falling movement. Furthermore, this is all that is valid for the case where the washing machine 11 has the blade 19 as described initially. The laundry item starts to fall downwards between points 3 and 4, at the end of the first quarter of a turn between points 3 and 4, where the quarter is counted counter-clockwise, counter-clockwise corresponding to the direction of rotation of the drum. At point 3, the laundry item is still in contact with the inner wall of the drum, starting there from continuing to point 4 and then falling downwards to point 5.

In the lower figure, the sliding movement of the laundry item is shown, which is again divided into five points. When compared with the falling motion, it is apparent that no falling down occurs, but the laundry items are always in contact with the inner wall of the drum. During the sliding, the article of clothing is at least partially simply flipped over.

In the right table of fig. 7, the coefficient of variation for ten points in the falling motion and four points in the sliding motion is shown, which is N in each case. From these, an average μ was calculated, which was 0.524013276 and 0.284096412. The value of N and the average μ can be used in the following formulas. For both movements, indicated below: n is ten and four respectively.

In fig. 8, an envelope curve of the motor current I is shown for an increasing number of samples, wherein the falling motion is three complete turns and, thereafter, the true sliding motion is two complete turns for the paddles in the drum. This all demonstrates, from the table of fig. 7: the coefficient of variation CV for sliding movement is significantly smaller than the coefficient of variation CV for falling movement.

In fig. 9, a falling motion for a washing machine having no paddle is shown. In comparison with fig. 7, the difference is that the laundry item starts to disengage from the drum at point 3, but this is all quite late in the second quarter of a turn. The corresponding current envelope of the motor current is shown in fig. 10, fig. 10 showing: the variation is even higher than in fig. 8. Correspondingly, the values are slightly higher than in fig. 7 according to the table of the coefficients of variation according to fig. 9.

The movement of the laundry item together with the drum is then shown again in fig. 11. This is all quite simple and means that the laundry item rotates exactly with the drum without any relative movement, neither sliding nor falling. Fig. 12 shows the corresponding current envelope of the motor current I, which does not vary very much. The corresponding coefficient of variation CV, again calculated according to the formula described initially, is again significantly higher than the coefficient of variation CV for the falling motion and for the sliding motion.

In fig. 13, the coefficients of variation are shown for three situations corresponding to the movement of the laundry items falling in the drum with paddles. When the various articles of clothing are distributed not only in one single location in the drum, but in particular in more than one location, for example after each of the three paddles 19, the CV varies for each of one third of each turn. It also changes again for each turn. This all shows that precise values are not available, but they are still used to detect the movement of the laundry item in the drum with sufficient accuracy.

Claims

1. A method for operating a washing machine, the washing machine comprising:

The roller is provided with a plurality of rollers,

A driving motor for the drum,

A power supply for said drive motor with respect to the monitoring of the motor current,

A washing machine controller, wherein the washing machine controller monitors and detects the motor current by means of the power supply,

The method comprises the following steps:

A. The drum with laundry items therein is rotated by means of the drive motor, and in so doing, the motor current, and thus also the rotational position of the drum,

B. The full revolution of the drum is divided into at least three rotating sections, and the motor current is monitored and recorded for each of the rotating sections,

C. the drum rotates at a constant rotational speed for at least three full revolutions,

D. For the motor current determined for each rotation section, calculating an envelope curve of the motor current, and calculating a standard deviation from the envelope curve using a formula,

E. The corresponding standard deviation is then divided by the average of the motor current or the envelope curve to determine a coefficient of variation for each rotation segment,

F. Determining the behavior of the laundry item by comparing the determined coefficient of variation for each rotating section with a stored value for the coefficient of variation, with respect to: whether the laundry items slide down along the drum inner wall, fall off the drum inner wall, or rotate with the drum during rotation in the drum, while remaining at substantially the same position on the drum inner wall,

G. from the determination of the behaviour of the laundry item, parameters such as temperature, duration, rotational speed, type and amount of additives used, etc. are determined for further operation of the washing machine with respect to the treatment of the laundry item.

2. The method of claim 1, wherein the formula for calculating the coefficient of variation is:

3. the method of claim 1, wherein the formula for calculating the standard deviation is: Where x _i is the data point value, μ is the sample average, and N is the sample size.

4. The method of claim 1, wherein the drum rotates for three full revolutions at a rotational speed between 30rpm and 90 rpm.

5. The method according to claim 1, wherein the method with steps a to F is performed several times for different rotational speeds in each case.

6. The method of claim 5, wherein the rotational speed is increased by 10% to 100%.

7. A method according to claim 1, wherein the method detects whether the laundry items in the drum are sufficiently evenly distributed by using a predetermined limit value for the coefficient of variation to compare with a measured value for the coefficient of variation, and if the comparison falls below the predetermined limit value, the rotational speed for the drum is changed to redistribute laundry items in the drum for a more even distribution to compensate for unbalance of the laundry items in the drum.

8. The method according to claim 6, wherein, in order to detect a sufficiently uniform distribution of the laundry items in the drum, the following is used: an initially determined weight of the laundry item, a stored value for the determined weight of the laundry item and for the coefficient of variation of the behavior of the laundry item falling from the drum inner wall, then performing the steps B to E in order to determine whether the value for the coefficient of variation determined in this way corresponds to the stored value, and

If this is not the case, changing the rotational speed and/or rotational direction of the drum, and

If this is the case, the drum rotates faster for high speeds, especially for spin-drying.

9. The method according to claim 6, wherein, in order to detect a sufficiently uniform distribution of the laundry items in the drum, the following is used: initially determined weight of the laundry item, a stored value for the change coefficient for the determined weight of the laundry item and for the behavior of the laundry item falling from the drum inner wall, steps B to E then being performed in order to determine whether the value for the change coefficient determined in this way corresponds to the stored value, and

If this is the case, the drum rotates faster for high speed or for spin-drying, and

If this is not the case, a check is made as to: whether the laundry item rotates with the drum, whether the weight of the laundry item is initially determined, whether a stored value of the change coefficient for the determined weight of the laundry item and for the behavior of the laundry item rotating with the drum is used, and then steps B to E are performed to determine whether the value of the change coefficient thus determined corresponds to the stored value for the behavior of the laundry item rotating with the drum, and

If this is the case, the drum rotates slower and then checks again to see if the laundry items still fall off the drum inner wall at a lower rotational speed, and

If this is not the case, steps B to E are performed at a constant rotational speed to determine if the determined value for the coefficient of variation corresponds to the stored value for the behavior of the laundry item sliding down the drum inner wall, and

If this is the case, the drum rotates faster and then checks again to see if the laundry still falls off the drum inner wall at a higher rotational speed, and

If this is not the case, a check is made according to claim 7 to see if the laundry item still falls off the drum inner wall while the rotation speed remains the same.

10. The method according to claim 7, wherein the treating of the laundry items is further performed in case the distribution of the laundry items is considered to be sufficiently uniform.

11. The method of claim 10, wherein the treatment process is a spin-drying process.

12. A method according to claim 1, wherein the laundry items in the drum are monitored with a wet out of water for detecting a sufficiently uniform wet out of the laundry items in the drum: initially determined weight of the laundry item, a stored value for the change coefficient for the determined weight of the laundry item and for a behavior of the laundry item rotating with the drum, then the laundry item is soaked by introducing water into or onto the drum, then steps B to E are performed to determine whether the value for the change coefficient determined in this way corresponds to the stored value for the behavior of the laundry item rotating with the drum, and

If this is the case, the drum rotates faster for high speed or for spin-drying process, and

If this is not the case, the rotational speed and/or rotational direction of the drum is changed.

13. Method according to claim 12, wherein in case the determined value for the coefficient of variation does not correspond to the stored value for the behaviour of the laundry article rotating with the drum, a check is made at a constant rotation speed with respect to: whether the laundry item falls from the drum inner wall, whether the weight of the laundry item determined at the beginning of use for this purpose, whether the stored value of the change coefficient for the determined weight for the laundry item and for the behavior of the laundry item falling from the drum inner wall is used, and then steps B to E are performed in order to determine whether the value for the change coefficient determined in this way corresponds to the stored value for the behavior of the laundry item falling from the drum inner wall, and

If this is the case, the drum rotates faster and then checks again to see if the laundry item is still rotating with the drum at the higher rotational speed, and

If this is not the case, steps B to E are performed at a constant rotational speed to determine if the determined value for the coefficient of variation corresponds to a stored value for the behavior of the laundry item sliding down the drum inner wall, and

If this is the case, the drum rotates faster and then checks again to see if the laundry item is still sliding down the drum inner wall at the higher rotational speed, and

If this is not the case, a check is made according to claim 7 to see if the laundry item is still rotating with the drum at the same rotation speed.

14. The method of claim 1, wherein the laundry items in the drum are monitored for a wash process with water using one of the following for detecting an appropriate wash process for the laundry items in the drum: a weight of the laundry item determined at the beginning for a stored value of the change coefficient of the behavior of the laundry item expected for the washing process for this determined weight of the laundry item, steps B to E then being performed to determine whether the value for the change coefficient determined in this way corresponds to the stored value of the expected behavior for the laundry item, and

If this is the case, the drum rotates at the same rotational speed and in the same direction for the next washing cycle, and

15. The method of claim 1, wherein the number or weight of the laundry items in the drum is determined at the beginning by weighing, or by monitoring the motor current as the drum with the laundry items therein rotates.

16. The method of claim 1, wherein the coefficient of variation is used in addition to the standard deviation and the mean deviation.

17. The method of claim 1, wherein in step B, the rotating sections are of equal size.

18. The method of claim 4, wherein the drum rotates for three full revolutions at a rotational speed between 55rpm and 65 rpm.

19. A washing machine, comprising:

The roller is provided with a plurality of rollers,

A driving motor for the drum,

Wherein the washing machine controller is designed to perform the method according to claim 1.