Method for operating a washing machine and washing machine

Abstract

The invention relates to a method for operating a washing machine with a tub for holding washing liquid, a ribless drum rotatably mounted in the tub for holding laundry, a motor for driving the ribless drum, and a control or regulating device, wherein the method comprises the following steps: a) rotating the ribless drum by means of the motor at a speed corresponding to a predetermined rotation rhythm; b) monitoring a variation in the drive torque of the motor; c) detecting laundry slipping and / or rolling on the drum when the monitored variation is less than or equal to a predetermined variation limit value for a predetermined period.Furthermore, the invention relates to a washing machine with a tub for receiving washing liquid, a ribless drum rotatably mounted in the tub for receiving laundry, a motor for driving the drum and a control and / or regulating device configured to carry out the method.

Description

[0001] The invention relates to a method for operating a washing machine and a washing machine. In particular, the invention relates to a method for operating a washing machine comprising a tub for holding washing liquid, a ribless drum rotatably mounted in the tub for holding laundry, and a motor for driving the drum, as well as a corresponding washing machine.

[0002] Washing machine drums typically have ribs inside. A rib, also called a drum wheel, is a part of the drum that, as the drum rotates, sets the laundry inside in motion, i.e., pulls it along. The rib is usually a plate inside the drum against which the laundry gets caught as the drum rotates, up to a certain height, and then falls back down, thus being agitated and redistributed. There are usually several ribs in the drum, spaced at predetermined intervals. The ribs are essential for redistributing the laundry during a wash cycle. A typical wash cycle consists of alternating clockwise rotation, pause, counterclockwise rotation, pause, clockwise rotation, pause, and so on.However, the ribs are additional components that incur costs.

[0003] Therefore, a ribless drum is desirable for washing machines. With a ribless drum, i.e., a drum without ribs, it sometimes happens that certain items of laundry cannot be properly washed by simply rotating the drum to a normal washing speed.

[0004] To prevent laundry from slipping and / or rolling on the ribless drum, pendulum rhythms are a known countermeasure from undocumented prior art. However, pendulum rhythms, in which the drum is moved in a pendulum motion at a predetermined rhythm, require high drive torques to move the drum.

[0005] The invention thus addresses the problem of providing a method for operating a washing machine with a ribless drum and a washing machine with a ribless drum in which slippage and / or rolling states of the laundry during a rotational movement of the ribless drum are detected. Furthermore, it is desirable to be able to initiate countermeasures which, in particular, do not require a sustained high load on the motor.

[0006] According to the invention, this problem is solved by a method with the features of claim 1 and a washing machine with the features of claim 10. Advantageous embodiments and further developments of the invention are described in the following dependent claims.

[0007] The advantages achievable with the invention, besides detecting whether the laundry is slipping and / or rolling on the drum, include the ability to take countermeasures to prevent the laundry from falling. Depending on the situation, targeted intervention against slipping and / or rolling laundry is possible. Furthermore, energy savings are achieved through lower drive torque: the process operates at a speed that only requires adjustment and / or regulation. Slipping and / or rolling laundry is reliably prevented. Additionally, the invention provides exceptional protection for the laundry, as forces are applied to the laundry only through frictional contact with the drum, rather than by pushing with ribs. A crease-reducing effect is achieved through continuous movement within the fabric of the laundry.

[0008] For the purposes of the invention, a ribless drum is a drum that does not have a rib or driver in its interior. However, it may have other protrusions and / or depressions that do not have the shape of the plate-like rib or driver. The drum, preferably the drum shell, preferably has depressions and / or protrusions other than a rib. It preferably has honeycomb-like structures, each formed as a raised area or depression. For the sake of simplicity, the ribless drum will hereinafter also be referred to simply as a drum.

[0009] The invention relates to a method for operating a washing machine with a tub for receiving washing liquid, a ribless drum rotatably mounted in the tub for receiving laundry, a motor for driving the drum and a control or regulating device, wherein the method comprises the following steps a) Rotating the ribless drum by means of the motor at a speed corresponding to a predetermined rotation rhythm; b) Monitoring a variation in the motor's drive torque; c) Detecting laundry slipping and / or rolling on the drum when the monitored variation is less than or equal to a predetermined variation limit value within a predetermined period.

[0010] The detection of slipping and / or rolling laundry is based on the drive torque of the drum motor. To detect slipping and / or rolling laundry, the variation (e.g., the variance) of this drive torque is monitored during the execution of the predetermined rotation cycle. A low variation over a longer period indicates rolling and / or slipping laundry. During the laundry drop, however, the drive torque varies due to differing loads as the laundry is lifted and dropped.

[0011] In step a), for example, a starting speed of 65 min⁻¹ is used, at which the drum rotates for a period of, for example, 180 seconds. The predetermined rotation rhythm according to step a) is executed, and during this time, step b) is executed. If no laundry slipping and / or rolling on the drum is detected, i.e., the monitored variation in the predetermined period is greater than the predetermined variation limit, the predetermined rotation rhythm continues to be executed and monitored. If the monitored variation in the predetermined period is less than or equal to the predetermined variation limit, it is detected, according to step c), that the laundry is slipping and / or rolling on the drum. Preferably, countermeasures are then taken to bring the laundry into a laundry trap, as explained below.

[0012] In a preferred embodiment, step b) includes filtering out higher-frequency components from the scatter of the drive torque with a cutoff frequency of at most 5.00 Hz, preferably 3.00 Hz, more preferably 2.00 Hz. Step b) is preferably performed using a PT1 filter. For the falling of the laundry, the low-frequency signal components of the drive torque are of particular interest. Therefore, higher-frequency components are preferably filtered out using the PT1 filter. The filtering is preferably performed with a cutoff frequency of 2.00 Hz.

[0013] Preferably, step b) comprises determining the scatter per drum revolution, inverting the determined scatter into an inverse, and smoothing the inverse over several drum revolutions, and step c) comprises detecting laundry slipping and / or rolling on the drum when the smoothed inverse is equal to or greater than a predetermined inverse threshold. Preferably, the scatter of the filtered drive torque is determined per drum revolution. This value is inverted (inverse 1 / scatter) and smoothed over several revolutions. If no laundry falls, the drive torque becomes more uniform, as no laundry needs to be lifted from a lower level. This uniformity leads to a decreasing scatter, causing the inverse to increase. Thus, the more the laundry slips and / or rolls, the higher the inverse value. If the filtered inverse scatter of the drive torque exceeds a certain threshold, i.e.,The inverse value, the inverse value limit, detects slipping and / or rolling of the laundry on the drum. This information is preferably used for further processing and / or changing the rotation rate, and the inverse variation is set to zero to restart the detection with the changed rotation rate. That is, following step c), speed control and / or regulation is preferably carried out, with steps b) and c) being executed after the inverse variation has been set to zero.

[0014] In a preferred embodiment, following step c), i.e., when the variation is less than or equal to the variation limit value, or when the reciprocal is equal to or greater than the predetermined reciprocal limit value, the speed control and / or regulation is performed as a function of a period of the drive torque. Preferably, when slipping and / or rolling laundry is detected, the speed control and / or regulation is performed to achieve a constant laundry fall. The speed control and / or regulation preferably includes determining the period of the drive torque, preferably in relation to the period of the rotational speed. Falling laundry results in the period of the drive torque being shorter than the period of the rotational speed. This period is therefore used for speed control and / or regulation to ensure a stable laundry fall.To control and / or regulate the rotational speed accordingly, the period of the drive torque is preferably evaluated in relation to the period of the rotational speed. Preferably, the drive torque filtered at the cutoff frequency PT1, or its unfiltered output signal, is filtered again with a further cutoff frequency of, for example, 0.08 Hz.

[0015] In a preferred embodiment, the speed control and / or regulation comprises evaluating the period of the drive torque by filtering the signals filtered with a cutoff frequency of at most 5.00 Hz, preferably 3.00 Hz, preferably 2.00 Hz, or the signals of the drive torque with a further cutoff frequency that is lower than the cutoff frequency, and determining the period of the drive torque between each pair of rising edge intersection points and two falling edge intersection points of the filtered signals, and determining a relative period by setting the determined period of the drive torque in proportion to a period of the speed, wherein A) if the determined relative period is greater than 90% and less than 110% and the current target speed is equal to or greater than 41 min⁻¹, the current target speed is reduced by a predetermined value; B) if the determined relative period is less than 80% and greater than 20% and the current target speed is less than 68 min⁻¹, the current target speed is increased by a further predetermined value; and C) if neither of the above conditions A) or B) is met, the rotation of the drum continues at the current target speed.

[0016] The predetermined value is, for example, 1, while the other predetermined value is, for example, 2. Preferably, the evaluation is performed after determining a new period, preferably once per laundry drop period. The other cutoff frequency is preferably at most 1.50 Hz, 1.00 Hz, more preferably 0.08 Hz.

[0017] In a preferred embodiment, the following steps are performed following step c): d) Checking the water level in the drum and, if there is water in the drum, pumping out the water in the drum, e) Performing a pendulum ramp-up to a set speed, f) Continuously performing speed control and / or regulation while carrying out steps b) and c), whereby, if laundry slipping and / or rolling on the drum is detected in accordance with step c), steps d) to f) are repeated.

[0018] Steps d) to f) are used to take countermeasures against slipping and / or rolling laundry identified in step c). In step f), a modified turning rhythm is preferably implemented.

[0019] In step e), the drum is preferably moved in a pendulum rhythm to reach the application speed. Step e) is preferably carried out analogously to a method described in DE 10 2020 108 677 A1 with reference to Fig. 5 therein, e.g. with a pendulum frequency of 0.9 Hz, A(n)Start of 20 min⁻¹, A(n)End = 110 min⁻¹, ΔA(n) = 30 min⁻¹.

[0020] A rotation pause is preferably performed between steps d) and e). This serves to regulate a minimum rhythm time. For example, a rotation pause of 13.75 seconds is recommended.

[0021] In a preferred embodiment, during a wash cycle between steps e) and f), a recirculation is performed while rotating the drum at the initial loading speed, and optionally, the drum remains at this speed. This recirculation can be performed during the wash cycle between steps e) and f). For example, this step can be performed at a speed of 110 to 120 rpm for a period of 4 seconds, with the speed being controlled and / or regulated according to the water level in the drum. Furthermore, the drum can optionally remain at the initial loading speed after the recirculation. The recirculation while rotating the drum at the initial loading speed serves to exchange the cleaning solution during the wash cycle.Maintaining a constant spin speed during the rinse cycle ensures that the laundry is less wet in the subsequent wash cycle and is less likely to slip or roll. This draining process at the spin speed can be achieved, for example, at a speed of 110 to 120 rpm for a period of 8 seconds.

[0022] In a preferred embodiment, following step c), the drum is rotated in the opposite direction.

[0023] The invention further relates to a washing machine with a tub for receiving washing liquid, a ribless drum rotatably mounted in the tub for receiving laundry, a motor for driving the drum and a control and / or regulating device configured to carry out a method according to one or more of the embodiments described above.

[0024] The washing machine can be designed as an automated washing machine or as a combination appliance such as a washer-dryer.

[0025] The washing machine can have a recirculation system designed to pump water from a first, preferably lower, area of ​​the tub to a second, preferably upper, area of ​​the tub, thus creating a recirculation. Position and direction specifications refer to the washing machine's standard operating position.

[0026] An embodiment of the invention is shown schematically in the drawings and is described in more detail below. It is shown schematically and not to scale. Fig. 1 shows a signal profile of filtered signals of a drive torque during the execution of a method according to the invention.

[0027] Fig. 1shows a signal profile of filtered signals of a drive torque during an execution of a method according to the invention.

[0028] The procedure consists of the following steps: a) Rotating the ribless drum by means of the motor at a speed corresponding to a predetermined rotation rhythm; b) Monitoring a variation in the motor's drive torque; c) Detecting laundry slipping and / or rolling on the drum when the monitored variation is less than or equal to a predetermined variation limit for a predetermined period.

[0029] Shown is the waveform of signal 1, obtained by filtering out higher-frequency components from the drive torque variation with a cutoff frequency of 2.0 Hz using a PT1 filter. Also shown is the waveform of another signal 2, filtered from signal 1 with a cutoff frequency of 0.08 Hz. Signal 1 contains fluctuations in the drive torque caused by a laundry drop and intersects signal 2 over time. Between each pair of rising and two falling crossover points of the signals, a period of the drive torque can be determined. Reference symbol list

[0030] 1 signal 2 further signal

Claims

1. A method for operating a washing machine comprising a tub for receiving washing liquid, a ribless drum rotatably mounted in the tub for receiving laundry, a motor for driving the ribless drum, and a control or regulating device, wherein the method comprises the following steps: a) rotating the ribless drum by means of the motor at a speed corresponding to a predetermined rotation rhythm; b) monitoring a variation in the drive torque of the motor; c) detecting laundry slipping and / or rolling on the drum when the monitored variation is less than or equal to a predetermined variation limit for a predetermined period.

2. Method according to claim 1, characterized by the fact that Step b) includes filtering out higher-frequency components from the scatter of the drive torque with a cutoff frequency of at most 5.00 Hz, preferably 3.00 Hz, more preferably 2.00 Hz, preferably using a PT1 filter.

3. Method according to claim 1 or 2, characterized by the fact that Step b) includes determining the dispersion per drum revolution, inverting the determined dispersion into an inverse value and smoothing the inverse value over several drum revolutions, and step c) includes detecting laundry slipping and / or rolling on the drum when the smoothed inverse value is equal to or greater than a predetermined inverse value limit.

4. Method according to any of the preceding claims, characterized by the fact that Following step c), a speed control and / or regulation is carried out depending on a period of the drive torque.

5. Method according to claim 4, characterized by the fact thatThe speed control and / or regulation involves evaluating the period of the drive torque by filtering the signals (1) filtered with the cutoff frequency or the drive torque signals with a further cutoff frequency lower than the cutoff frequency and determining the period of the drive torque between each pair of rising edge intersection points and two falling edge intersection points of the filtered signals (1, 2) and determining a relative period by setting the determined period of the drive torque to a period of the speed, wherein A) if the determined relative period is greater than 90% and less than 110% and a current target speed is equal to or greater than 41 min -1 a) if the current target speed is reduced by a predetermined value, b) if the determined relative period is less than 80% and greater than 20% and the current target speed is less than 68 min -1is, the current target speed is increased by a further predetermined value, and C) if neither of the two above conditions A) or B) is met, the rotation of the drum continues at the current target speed.

6. Method according to one of the preceding claims 4 or 5, characterized by the fact that Following step c), the following steps are to be carried out: d) checking the water level in the drum and, if there is water in the drum, pumping out the water in the drum, e) performing a pendulum ramp-up to a set speed, f) continuously carrying out the speed control and / or regulation while performing steps b) and c), whereby, if laundry slipping and / or rolling on the drum is detected in accordance with step c), steps d) to f) are repeated.

7. Method according to claim 6, characterized by the fact that A rotation break is performed between steps d) and e).

8. Method according to claim 6 or 7, characterized by the fact that During a rinsing cycle, between steps e) and f), a recirculation is performed while rotating the drum at the docking speed and optionally remaining at the docking speed.

9. Method according to any of the preceding claims, characterized by the fact that Following step c), the drum is rotated in the opposite direction.

10. Washing machine with a tub for receiving washing liquid, a ribless drum rotatably mounted in the tub for receiving laundry, a motor for driving the drum and a control and / or regulating device configured to carry out a method according to one of the preceding claims.

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