DE102015205945A1 - Method for operating a washing machine with foam detection by a drum speed evaluation and this suitable washing machine - Google Patents

Abstract

The invention relates to a method for operating a washing machine 1 with a tub 2, a drum 3 for receiving laundry items 4, a drive motor 5 for the drum 3, and a control device 8, wherein a presence of foam in a washing phase WP by measurement and analysis the drum speed mn measured during a drum rotation period Δtn is detected by first measuring a reference value mref in the absence of foam for the drum speed mn and comparing it with a washing phase drum speed mWP subsequently measured in the washing phase WP, the ratio x = mWP / mref by comparison with a given for the washing phase WP number a is evaluated in terms of the presence of foam. The invention also relates to a washing machine 1 suitable for carrying out the method.

Description

The invention relates to a method for operating a washing machine with foam detection by an evaluation of the rotational speed of a drum of the washing machine for receiving laundry items (laundry drum) and a washing machine suitable for this purpose. More particularly, the invention relates to a method for operating a washing machine with a tub, a drum for receiving laundry, a drive motor for the drum, and a control device, and a suitable for carrying out this method washing machine.

In a washing machine, laundry is generally treated in a washing phase for cleaning with a detergent containing wash liquor. In addition, after a rinsing phase with water in which wash liquor and / or soiling present in or on the laundry are removed, a treatment of the laundry with a fabric softener is frequently carried out. For reasons of cost and environmental protection, it makes sense to use an optimum amount of laundry treatment agent (in particular laundry detergent and softener). An overdose but also an underdose should be avoided. In particular, an incorrect dosage of the detergent can cause overfoaming (overdosing).

In a washing machine too much foam is often generated due to incorrect use of detergent, especially overdosage of detergent, but also, for example, incorrect selection of a wash program. This is harmful in many ways. Thus, an excessive amount of foam reduces the force on the laundry items to be treated as well as the relative movement of laundry items in the drum.

In addition, the resulting in the wash foam on the spin cycle has a detrimental effect, because he has a braking effect between a laundry drum and a tub, as a result, the spin at low speed shows an unsatisfactory performance or an engine for the laundry drum during the spin cycle overtaxed and possibly damaged. Moreover, if during the course of a washing process, a large amount of foam is present in the tub of a washing machine or arises during spinning, the lye pump does not promote the foam / lye mixture. The spin is therefore not performed in foam detection in the pumping or stopped in the event of foam detection during spin. In addition, the foam can escape from the openings of the tub as well as the tub ventilation and the filling hose. Early foam detection and efficient measures to remove the foam are therefore important.

Overall, the washing performance in a washing machine can decrease dramatically due to excessive foaming. It may leak in a particularly unfavorable case foam during a wash program from a washing machine, which may damage the mechanical and electronic components of the washing machine. In addition, furniture, the floor and the environment can be affected in the installation room of the washing machine.

To avoid the above-mentioned disadvantages, various ways of detecting or eliminating the foam are known.

In general, to detect the formation of foam by means of a sensor, the pressure in a tub is measured. Usually, a pressure sensor is used for this, which is also suitable for determining the water level in the tub. Frequently, the presence of foam (liquid-air mixture) is detected by a pressure build-up during washing or spinning or by a much slower pressure decrease during pumping.

From the DE 36 38 498 A1 is a washing machine is known, which has a pressure sensor as a measuring device whose output signals are an indication of foaming during the spin process and constitute control variables for the drive motor of the washing drum and thus for the control of the spin speed. This pressure sensor is part of a connected to the tub and thus with the lye system of the washing machine pipeline. If an increase in the drum water pressure is measured via the pressure sensor and thus a formation of foam in the lye system is detected, corresponding switching steps for the drive motor of the washing drum are triggered.

The DE 102 34 472 A1 describes a method for removing foam in a tub of an electronically controlled drum washing machine as a result of a program step, which is intended for dehydration of the tub, with an attached at the bottom of the tub lye drain system with a drain pump and with a sensor for determining the height of the tub located in the tub Liquid. The trace of the sensor signal (P) recorded during operation of the leach pump contains a gradient ΔP _n / Δt _n as compared to ΔP _n-1 / Δt _n-1 indicating the presence of foam, whereupon then a graded foam treatment measure is initiated.

The DE 10 2006 027 197 A1 describes a method for removing foam in a tub of an electronically controlled drum type washing machine, wherein after a main wash and pumping out the liquid the following steps are performed: a) alternately rotating the drum at a low speed U ₁ and stopping the drum and pumping off the liquid b) taking in water in an amount sufficient to cover all the waterways, and purging for a short period of time t ₂ , with a level control over a very small hysteresis, c. for a period t ₁ of 30 seconds to 15 minutes; ) Pumping off the liquid while the drum is being moved at a low speed U ₂ .

• – Schaumdetektion beim Abpumpen bei Stillstand der Trommel mittels Auswertung der Gradienten im Druckverlauf bei einem Sensor (z.B. einem Gebergehäuse, das im Allgemeinen einen Luftschlauch enthält, in dem durch Zusammendrücken von Luft die Menge an vorhandenem Wasser bestimmt werden kann);
• – Schaumerkennung mittels eines im Schleudern detektierten Druckniveaus im Gebergehäuse.

In general, a foam detection is used when pumping the wash liquor and when rinsing. Preferably, one of the following measures is taken:

• - Foam detection when pumping down when the drum is stopped by evaluation of the gradient in the pressure curve at a sensor (eg a transmitter housing, which generally contains an air hose in which the amount of water present can be determined by compressing air);
• - Foam detection by means of a detected in spinning pressure level in the encoder housing.

The detection of foam is usually activated during spinning. The rotation of the drum causes a radial release of foam and distribution. Via the detected air seal of a transmitter housing, a pressure increase is detected, which is measurable at the pressure sensor. The known methods for detecting foam are based on exceeding a threshold (pressure threshold), which is used to register the presence of foam and generally to initiate a foam removal operation.

A disadvantage of the known method is that it comes due to the imbalance of laundry and existing residual water that is produced during spinning, by simulating an apparent pressure increase to measurement errors. The occurrence of pressure spikes may indicate the presence of foam, even though there is no foam at all. This is due to variations in pressure measurement with a sensor, where the errors in signal acquisition, conversion or processing also depend on whether a digital or analog controller is used. Since negative values are sometimes not detected by a sensor, it is not the true average value that would result if negative proportions were recorded, but an increased pressure of the oscillating water quantity. Moreover, the pressure signals measured by the sensor increase with the rotational speed, so that the pressure threshold value predetermined for the foam detection is prematurely exceeded. In digital controllers, in addition to fluctuations in pressure, pumping effects (water trailing during spinning, "snorkeling") cause the limit to be reached prematurely and the regulator is triggered to trigger a defrosting action.

The foam detection in a drum washing machine (also abbreviated herein as a "washing machine") can also be carried out via a conductance measurement with two electrodes in the lower region of the tub.

The DE 41 04 151 A describes a laundry treatment machine with a program control device for controlling the program flow, a rotatably mounted in a tub drum, a drive motor for the drum, a heater and a device for Schaumsensierung, which has switching means, the foam detection on a turning on the heater and / or a slow rotation cause the drum. The device for foam sensing is designed, in particular, as a conductivity measuring device, as a pressure measuring device or as a light barrier arrangement.

The DE 10 2008 028 030 A1 describes a method for determining a foam forming within the liquor contained in a tub of a washing machine. It uses electrodes to which a measuring voltage is applied. By determining the electric field between the electrodes and assigning a measure of the amount of foam to the magnitude of the electric field, the formation of foam can be detected in time to take corrective action, especially during a wetting or start of a wash cycle of a laundry treatment process can be. For carrying out this method, a device consists essentially of a measuring transducer, which has two electrodes within a channel-like housing, which can be flowed through from bottom to top, whose electric field present in their distance space indicates the electrical conductivity of the liquor. which changes significantly when the liquor carries foam bubbles.

In addition, a foam detection during spinning by means of an evaluation of the target / actual speed difference is possible. In the Foam detection by evaluating the target / actual speed difference is made use of the fact that the foam can brake a rotating drum, whereby there is a difference between the target and the actual speed. In this case, the association between a specific foam concentration and the target / actual difference is generally stored in a data memory of the drum washing machine.

The DE 10 2010 028 614 A1 describes a pump device for a water-conducting household appliance with a detection unit for detecting at least one electrical parameter of a drain pump and a control unit which controls the drain pump via a power stage, wherein the control unit evaluates the electrical parameters detected by the detection unit and depending on the result of the evaluation Activation of the drain pump influenced. In one embodiment, the control unit is configured to detect foaming from the detected electrical parameters when pumping out via the drain pump.

The DE 197 38 845 A1 describes a washing and / or drying device, with a drum receiving the laundry, which is rotatably mounted on a drum shaft and driven in rotation via a directly engaging with the drum shaft drive motor, and a control device controlling the operation and with a means for receiving at least one engine-specific Parameters, in particular an operating parameter, which after further processing provides an information value (eg drive torque and / or speed of the drive motor), in dependence of which the control of the further operation takes place.

The EP 0 657 576 B1 describes a method for determining an undesired braking of the laundry drum during a spin section in an automatically controlled washing machine with a drive motor whose speed is adjustable with a speed control circuit and determined according to target and actual speed values and for driving the laundry drum with several different speeds for washing, rinsing and spin serves. In this case, the control circuit of the washing machine during a spin section, a signal is supplied, which is a measure of an unwanted braking of the laundry drum and is determined by the ratio of the parameter target speed, actual speed and a load-dependent electrical variable. The load-dependent electrical variable is, for example, the current consumption of the drive motor. In one embodiment, upon application of the signal having a magnitude indicative of the presence of a quantity of foam that slows the drum, the spin drive of the drum is turned off, at least for a limited duration.

The DE 10 2007 042 968 A describes a method for detecting foam in a drum washing machine with a program control for controlling a program flow, a rotatably mounted drum in a tub, a water supply system, a bottom of the tub arranged Laugenablaufsystem with a drain pump, a drive motor for the drum and a sensor for determining a signal of a liquid contained in the tub and optionally containing foam, wherein the sensor during the rotation of the drum at a high speed U _n a signal S _{n is} measured and compared with one of these speed U _n stored in the program control associated value W _n , wherein value pairs U _n and W _n (n ≥ 1) are stored in the program control for at least two rotational speeds and the presence of foam is registered when the value W _n is reached or exceeded, ie when the condition S _n ≥ W _{n is} satisfied.

Against this background, it was an object of the present invention to provide a method for the detection of foam during a washing program carried out in a washing machine, which allows the detection of foam in a simple and precise manner, the detection in particular also should not lead to a prolonged service life. The object of the invention was also to provide a suitable for carrying out this method washing machine.

According to the invention, this object is achieved by a method and a washing machine according to the independent patent claims. Preferred embodiments of the invention are listed in the respective dependent claims. Preferred embodiments of the method correspond to preferred embodiments of the washing machine, even if not separately pointed out here in each case.

The invention thus relates to a method for operating a washing machine with a tub, a drum for receiving laundry, a drive motor for the drum, and a control device, wherein a presence of foam in a washing phase WP by measuring and analyzing the during a drum rotation period .DELTA.t _n measured drum speed m _{n is} detected by first in the absence of foam for the drum speed m _n a reference value m _{ref is} measured and with a subsequently measured in the washing phase WP washing phase drum speed m ^WP ratio, the ratio m ^WP / m _ref by Comparison with a for the washing phase WP is predetermined number a in view of the presence of foam is evaluated. The number a is in this case generally selected on the basis of a selected washing program and the type and / or quantity of the laundry items. Since a certain amount of foam can often be tolerated, evaluation with regard to a "presence of foam" in particular means an evaluation with regard to an intolerable amount of foam.

• (a) Bereitstellung im Laugenbehälter einer waschmittelhaltigen wässrigen Flüssigkeit;
• (b) Bestimmung eines Referenzwertes m_ref für die Trommeldrehzahl m der Trommel als Maß für einen schaumlosen Zustand, wobei der Referenzwert m_ref gleich einer einzigen gemessenen Trommeldrehzahl m₁ ist oder eine durch Mittelung von mehreren gemessenen Trommeldrehzahlen m_n (n > 1) erhaltene mittlere Trommeldrehzahl (m_n)^med ist, wobei die Trommeldrehzahl m_n (n ≥ 1) jeweils unter einer Referenzbedingung, nämlich als ein Mittelwert während eines Trommeldrehzeitraumes Δt_n, während dem der Antriebsmotor mit einem vorgegebenen Antriebsstromwert I_A betrieben wird, gemessen wird;
• (c) Speicherung von mindestens dem Referenzwert m_ref in der Motor-Trommel-Kontrolleinheit;
• (d) Starten einer Waschphase WP mit den Wäschestücken in der im Schritt (a) bereitgestellten wässrigen Flüssigkeit;
• (e) Messung während der Waschphase WP von Waschphasentrommeldrehzahlen m_n ^WP (n ≥ 1) unter der Referenzbedingung, indem m_n ^WP jeweils als Mittelwert während des Trommeldrehzeitraumes Δt_n, während dem der Antriebsmotor mit dem vorgegebenen Antriebsstromwert I_A betrieben wird, gemessen wird;
• (f) für den Fall, dass n = 1 ist, Speicherung der Waschphasentrommeldrehzahl m₁ ^WP als Waschphasenwert m^WP der Trommeldrehzahl m_n in der Motor-Trommel-Kontrolleinheit und für den Fall, dass n > 1 ist, Speicherung der durch Mittelung von mehreren gemessenen Waschphasentrommeldrehzahlen m_n ^WP erhaltenen mittleren Waschphasentrommeldrehzahl (m_n ^WP)^med als Waschphasenwert m^WP der Trommeldrehzahl m_n in der Motor-Trommel-Kontrolleinheit;
• (g) Berechnung des Verhältnisses x = m^WP/m_ref; und
• (h) Feststellung eines vorhandenen Schaumes für den Fall, dass x > a ist.

In a particularly preferred embodiment of this method, the following steps are carried out using a motor-drum control unit:

• (A) provision in the tub of a detergent-containing aqueous liquid;
• (b) determining a reference value m _ref for the drum speed m of the drum as a measure of a foamless condition, wherein the reference value m _{ref is} equal to a single measured drum speed m ₁ or one obtained by averaging several measured drum speeds m _n (n> 1) ^med drum rotational speed (m _n ) ^med , wherein the drum speed m _n (n ≥ 1) each under a reference condition, namely as an average during a drum rotation period .DELTA.t _n , during which the drive motor is operated with a predetermined drive current value I _A , is measured;
• (c) storing at least the reference value m _ref in the engine drum control unit;
• (d) starting a washing phase WP with the laundry items in the aqueous liquid provided in step (a);
• (e) Measurement during the wash phase WP of wash phase drum speeds m _n ^WP (n ≥ 1) under the reference condition by measuring m _n ^WP as an average during the drum rotation period Δt _n during which the drive motor is operated at the predetermined drive current value I _A ;
• (f) in the case where n = 1, storing the washing phase drum speed m ₁ ^WP as the washing phase value m ^{WP of} the drum speed m _n in the motor drum control unit and in the case where n> 1 storing the averaging of a plurality of measured wash phase drum speeds m _n ^WP mean wash phase drum speed (m _n ^WP ) ^med as washing phase value m ^{WP of} the drum speed m _n in the motor drum control unit;
• (g) calculating the ratio x = m ^WP / m _ref ; and
• (h) detecting an existing foam in case x> a.

Accordingly, the case x ≤ a means that there is no foam or negligible amount of foam.

Different wash programs will generally have different reference drum speed values m _R.

The motor-drum control unit may be a separate control unit or integrated into the control device. Specifically, the engine-drum control unit may determine the drum speed m _n , the drive current value I _A, and the drum rotation period Δt _n .

In the process according to the invention, steps (b) and (e) are generally carried out, while the same amount of aqueous liquid, which is also referred to as wash liquor, is present in the suds container. In general, there is also a certain amount of laundry items in the drum, which is no longer changed between steps (b) and (e).

"Reference condition" here means in particular that for the determination of the reference value m _ref for the drum speed of the drum as well as for the determination of the washing phase value m ^WP the drum speed at a single or multiple measurement of the drum speed m _n respectively the same conditions with respect to the drive current I _A of the drive motor and the drum rotation period .DELTA.t _{n are} selected. For example, if the drum rotation period .DELTA.t values _n selected 30 sec and 50 sec, that is, two reference measurements carried out, drum rotation periods are .DELTA.t _n of 30 seconds and used 50 sec in the determination of drum speeds m _n ^WP in the washing phase WP also.

In particular, "foamless state" means that the detergent-containing aqueous solution contains no foam or generates no foam.

The reference value m _ref is preferably a mean drum speed (m _n ) ^med obtained by averaging at least two measured drum speeds m _n (n ≥ 2). This can be represented by the following formulas

Reference _{drum speed} m _ref : m - _refn = 1 / nΣn / 1m _refn and drum speed m ^WP during the washing phase WP: m - _n = 1 / n nΣ / 1m _n According to the invention, it is preferred that the drum speed m _n during the drum rotation period Δt _{n is} measured only after a predetermined time Δt _set . Particularly preferably, this predetermined time Δt _{set is} 1 to 3 seconds. This reduces or eliminates a negative influence due to higher turnover at the beginning.

It is also preferred that the drum speed m _n during the drum rotation period Δt _{n is} measured only when its fluctuation is less than 10% around an average. This generally means that the drum speed m is measured when a steady-state condition is reached at which only a general small variation in drum speed m _n occurs.

Both result in the actually considered drum rotation period Δt _{n being} shorter and corresponding to a so-called "effective reference time", eg Δt _r1 or Δt _r2 . Accordingly, then the drum speed m _n would be measured as "effective drum speed", for example as m _r1 or m _r2 .

It is a particular advantage of the invention that the reference value m _ref can be measured at room temperature. This means, in particular, that a heating device which is generally present in the washing machine does not have to be switched on for the measurement of the reference value. Instead, the heater is usually put into operation only when the aqueous liquid, ie the washing liquor for the washing phase, is heated to a desired washing temperature.

A rotational speed _{mn of} the drum is generally ≦ 100 revolutions / min during the drum rotation period Δt _n, and is preferably in the range of 20 to 70 revolutions / min, and more preferably in the range of 25 to 60 revolutions / min, more preferably in the range of 25 to 40 revolutions / min, which, of course, variations due to the invention, since in particular a change in the drum speed is measured due to a possible foaming.

The drum rotation period Δt _n according to the invention is preferably in the range of 10 to 50 seconds, more preferably in the range of 20 to 40 seconds, and most preferably in the range of 25 to 35 seconds.

In general, according to the invention, an existing foam, i. In general, too much foam is found when x is greater than 1.5, that is, a is 1.5. However, the value of a may be set taking into account a selected washing program and, in particular, taking into account the type and / or amount of items to be washed. For example, under certain conditions, a value of a ≤ 2.5 could be considered acceptable, as a corresponding amount of foam may be considered tolerable.

In any case, the drive motor is generally stopped when x is greater than an upper limit a _max . This is to protect the washing machine and / or a storage room of the washing machine from damage caused by excessive foam generation.

In general, in carrying out the process of the invention, not only is a foam, i. the presence of foam itself, noted. Typically, the presence of foam is indicated to a user on a display device that is generally present and / or measures are taken to reduce the amount of foam (also referred to as "foam" measures) upon detection of foam. The measures for reducing the amount of foam can be carried out automatically or by a user of the washing machine.

A preferred measure here is that the aqueous liquid is diluted by addition of water or by a combination of pumping out of aqueous liquid and addition of water. Upon completion of an initiated measure to reduce the amount of foam, a new reference value m ^new for the drum speed m of the drum is typically determined by repeating step (b). It should be noted at this point that the expressions "m" and m _n "are used here essentially with the same meaning, but m _n expresses more strongly that according to the invention several, namely" n ", drum speeds can be measured.

Incidentally, other methods for reducing the amount of foam can also be used, for example a reduced movement program of the drum and / or a cooling of the wash liquor. Moreover, for example, so-called "reversing pauses" or "drum standstill phases" may be introduced until the foam concentration has decreased to an acceptable level. On the other hand, in embodiments of the invention, the foam could be controlled by heating the foam bubbles which are thereby burst.

The measurements in the washing phase WP are generally repeated, so that generally more than so-called detection steps, ie steps for the possible detection of foam, are carried out. However, it is also possible to disable the execution of detection steps. This is especially the case when pumping out of washing liquor occurs before a rinsing phase, or new laundry items are added. In the latter case, anyway, a new reference value m _ref would have to be ^{newly determined} for the drum speed m.

In a preferred embodiment of the method, a measurement of m is in particular also carried out at the end of a washing phase WP, ie generally immediately before the pumping out of the aqueous liquid, ie the wash liquor and the control of a rinse phase occurs in view of a detected amount of foam.

Finally, it is preferred according to the invention that steps (b) and (c) are subsequently carried out on a wetting phase with items of laundry. Wetting phase is understood to mean the phase in a washing program in which items of laundry to be cleaned and in particular to be washed with wash liquor are wetted with a wash liquor to be used, generally up to a saturation of the laundry items with the wash liquor. In this case, the laundry items are generally weak or not at all moved. It is therefore in a wetting phase generally only a small separation of dirt from the laundry to be washed. In particular, a laundry drum in a wetting phase is preferably not rotated at a drum speed of more than 25 revolutions per minute.

The method according to the invention can be controlled particularly well if the amount of aqueous liquid is exactly known, and in particular also the amount of water used in a foam measure.

The amount of aqueous liquid can be determined, for example, by measuring an amount of water introduced into the tub by means of a water meter, taking into account the proportion of water introduced by the items of laundry and determining the so-called free liquor. This can be done, for example, that a hydrostatic pressure sensor is arranged in the tub and used to measure the hydrostatic pressure as a measure of the free fleet.

For the determination of a suitable value for a, in particular the loading amount with items of laundry can also be taken into account. The load of laundry may be adjusted by a user or preferably determined automatically in the washing machine. In this case, the determination of the loading amount by measuring the increase in weight of the drum due to the loading of laundry done or by analyzing the suction behavior of water by the change of hydrostatic pressure is analyzed during an addition of water to dry laundry. For this purpose, a hydrostatic sensor is advantageously present in a washing machine according to the invention. Particularly advantageous is then also a water meter, i. a measuring device for determining the amount of water charged, or the amount of filled wash, present. Thus, for example, the hydrostatic pressure p measured with the aid of the hydrostatic sensor can be compared with the filled-in amount of water. The laundry items in the drum absorb water. The absorbed water can not contribute to an increase of the hydrostatic pressure. By comparing the measured hydrostatic pressure p and the accumulated amount of water - the absolute values and their temporal change - with corresponding, stored in the control device of the washing machine values for the moistening of laundry can be the load of laundry and possibly their Durchfeuchtungsgrad (degree of wetting) determine.

However, the present invention enables the determination of foam without the need for additional sensors.

A wash phase generally follows a wetting phase. If a washing program is signaled that sufficient wetting of the laundry is given, for example, by reaching a predetermined threshold value p ₁ for the hydrostatic pressure p and a predetermined threshold value (Δp / Δt) ₁ for the temporal gradient of the hydrostatic pressure p Generally the washing phase. According to the invention, this is the optimal time for carrying out the method according to the invention and in particular the determination of the reference value m _ref for the drum speed m.

The invention also relates to a washing machine with a tub, a drum for receiving laundry, a drive motor for the drum, and a control device, wherein the control device is adapted to carry out a method for their operation, in which a presence of foam in a washing phase WP is detected by measurement and analysis of the _n measured during a drum rotation period .DELTA.t drum speed m _n of the drum, by the absence of foam for the drum speed m _n first a reference value m _ref is measured and with a subsequently measured in the washing phase WP washing phase drum speed m ^WP into Ratio is set, wherein the ratio x = m ^WP / m _ref is evaluated by comparison with a predetermined for the washing phase WP number a in terms of the presence of foam.

• (a) Bereitstellung im Laugenbehälter einer waschmittelhaltigen wässrigen Flüssigkeit;
• (b) Bestimmung eines Referenzwertes m_ref für die Trommeldrehzahl m_n der Trommel als Maß für einen schaumlosen Zustand, wobei der Referenzwert m_ref gleich einer einzigen gemessenen Trommeldrehzahl m₁ ist oder gleich einem Mittelwert von mehreren gemessenen Trommeldrehzahlen m_n (n > 1) ist, die ihrerseits jeweils unter einer Referenzbedingung erhalten wurden, nämlich als ein Mittelwert während eines Trommeldrehzeitraumes Δt_n, während dem der Antriebsmotor mit einem vorgegebenen Antriebsstromwert I_A betrieben wird;
• (c) Speicherung von mindestens dem Referenzwert m_ref in der Motor-Trommel-Kontrolleinheit;
• (d) Starten einer Waschphase WP mit den Wäschestücken in der im Schritt (a) bereitgestellten wässrigen Flüssigkeit;
• (e) Messung während der Waschphase WP von Waschphasentrommeldrehzahlen m_n ^WP (n ≥ 1) unter der Referenzbedingung, indem m_n ^WP jeweils als Mittelwert während des Trommeldrehzeitraumes Δt_n, während dem der Antriebsmotor mit einem vorgegebenen Antriebsstromwert I_A betrieben wird, gemessen wird;
• (f) für den Fall, dass n = 1 ist, Speicherung der Waschphasentrommeldrehzahl m₁ ^WP als Waschphasenwert m^WP in der Motor-Trommel-Kontrolleinheit und für den Fall, dass n > 1 ist, Speicherung der durch Mittelung von mehreren gemessenen Waschphasentrommeldrehzahlen m_n ^WP erhaltenen mittleren Waschphasentrommeldrehzahl (m_n ^WP)^med als Waschphasenwert m^WP der Waschphasentrommeldrehzahl m_n der Motor-Trommel-Kontrolleinheit;
• (g) Berechnung des Verhältnisses x = m^WP/m_ref; und
• (h) Feststellung eines vorhandenen Schaumes für den Fall, dass x > a ist.

In a particularly preferred embodiment, the washing machine includes a motor-drum control unit, and the control device is configured to perform a method in which the following steps are performed using the motor-drum control unit:

• (A) provision in the tub of a detergent-containing aqueous liquid;
• (b) determining a reference value m _ref for the drum speed m _n of the drum as a measure of a foam-free state, wherein the reference value m _ref equal to a single measured drum speed m is ₁ or equal to an average of several measured drum speeds m _n (n> 1) which have been respectively obtained under a reference condition, namely, as an average value during a drum rotation period Δt _n , during which the drive motor is operated with a predetermined drive current value I _A ;
• (c) storing at least the reference value m _ref in the engine drum control unit;
• (d) starting a washing phase WP with the laundry items in the aqueous liquid provided in step (a);
• (e) Measurement during wash phase WP of wash phase drum speeds m _n ^WP (n ≥ 1) under the reference condition by measuring m _n ^WP each as an average value during the drum rotation period Δt _n during which the drive motor is operated at a predetermined drive current value I _A ;
• (f) in the case where n = 1, storing the wash phase drum speed m ₁ ^WP as the wash phase value m ^WP in the motor drum control unit and in the case where n> 1, storing the one by averaging several measured wash phase drum speeds m _n ^WP obtained mean wash phase drum speed (m _n ^WP ) ^med as wash phase value m ^WP the wash phase drum speed m _{n of} the motor drum control unit;
• (g) calculating the ratio x = m ^WP / m _ref ; and
• (h) detecting an existing foam in case x> a.

According to the invention, a washing machine is preferred in which a temperature sensor is arranged in the tub and different values of a are stored in the control device for different temperature values measured with the temperature sensor.

A washing machine used herein generally also has a heating device and a liquor drainage system with a drain pump arranged at the bottom of a liquor container. In addition, a washing machine used herein also generally includes laundry drippers and / or scooping devices.

Finally, the washing machine according to the invention may be a washing machine as such or a washer-dryer, ie a device which has the functions of a dryer and a washing machine.

The washing machine according to the invention preferably has an acoustic and / or visual display device for displaying one or more operating states, in particular the presence of foam and optionally the amount of foam. An optical display device may be, for example, a liquid crystal display on which certain prompts or indications are given. It may also or alternatively light LEDs in one or more colors light up. For example, it can be displayed on the basis of differently colored representations whether a washing phase WP takes place at a not too high foam concentration or not.

The method according to the invention can be used by determining too low measured values of x also with regard to a possible underdosing of detergent. On the display device can then be given to a user of the washing machine an indication to fill additional detergent, in which case also a quantity can be specified. The indication of the dosage recommendation can be made on the display screen as such or on a display field thereof (collectively referred to herein as a "display display"). The dosage recommendation can be displayed on the display in the form of a text and / or a sign. A suitable text would be, for example, the direct request "please dose" green "", where "green" is an indication of a dosing. Other colors may be mentioned or other indications given in text form.

In embodiments of the invention, the knowledge of the amount of water flowing into the tub or water is important. Preferably, therefore, in the washing machine according to the invention a measuring device for determining the filled amount of water is present, for example, a timing device for determining the opening period of a feed valve for the water or a liquid amount measuring device for measuring the amount of water filled.

The invention has numerous advantages. A method is provided for operating a washing machine in which the presence of foam can be determined qualitatively and quantitatively in a simple manner. The presence of foam can be detected precisely. By more accurately determining the presence of foam and in embodiments of the invention of an actual amount of foam in a washing program, on the one hand, it can be prevented from becoming one Fuming the washing machine comes, which may be associated with a water damage in an apartment. On the other hand, an excessive use of rinse water could be avoided, which would be required if excess detergent would have to be removed from the laundry. In addition, the invention allows a rapid implementation of remedial measures, also referred to as foam measures, in terms of the foam control itself but also with regard to an over or under dosage of detergent.

The inventive method also allows the operation of a washing machine in a tolerance range for the amount of foam, since in embodiments of the invention can be precisely adjusted when an excessively high amount of foam is present. In principle, the type and quantity of the items of laundry and their degree of soiling can be taken into account. Thus, despite the detection of the presence of foam, the washing machine can perform an entire washing process without disturbing or changing set program parameters if the amount of foam produced remains within the tolerance range.

The invention will be illustrated below with reference to a non-limiting embodiment of a washing machine according to the invention, reference being made to FIGS 1 to 3 ,

1 shows a schematic representation of the relevant parts of the invention for a first embodiment of a washing machine according to the invention, in which a method according to the invention can be carried out.

2 shows the profile of the drive current value I _A and the drum speed m _n while two drum rotation periods .DELTA.t _n (n = 1, 2) during step (b) of the process according to the invention, a reference value m _ref determined at the non-foam state, and in the motor-drum Control unit is stored.

3 shows the profile of the drive current value I _A and the drum speed m while two drum rotation periods .DELTA.t _n (n = 1, 2) during step (e) of the process according to the invention, in which, after starting a washing phase, a washing phase the drum speed m ^WP of the drum measured, and (in steps g) and (h) of the method according to the invention with the reference value m _ref with respect to a possible detection of foam is evaluated.

The washing machine 1 of the 1 has a tub 2 in which a drum 3 rotatably mounted and by the drive motor 5 is drivable. For improved ergonomics is the axis of rotation 19 the drum 3 from the horizontal by a small angle (eg 13 °) directed forward above, allowing the user of the washing machine 1 easier access and insight into the interior of the drum 3 Has. By this arrangement, in cooperation with Wäschemitnehmern 14 and scooping devices 17 for the detergent-containing aqueous liquid 7 , For example, wash liquor, on the inner surface of the drum shell also also an intensification of the flow of laundry items 4 with washing liquor 7 reached.

The washing machine 1 also has a liquor inlet system, which is a water connection fitting for the domestic water network 20 , an electrically controllable valve 21 and a supply line 13 to the tub 2 optionally including a detergent dispenser tray 12 can be guided, from the incoming water detergent portions in the tub 2 can transport. It is also in the tub 2 a heating device 16 for heating water or washing liquor 7 , The valve 21 as well as the heater 16 can by a control device 8th in response to a program schedule associated with a timed program and / or the achievement of certain measurements of parameters such as liquor level, liquor temperature, drum speed, etc. within the washing machine 1 can be bound. 9 means a motor-drum control unit, which in particular can determine and store the drum speed m _n , the drive current value I _A and the drum rotation period Δt _n .

6 means a pressure sensor, ie a sensor for measuring the hydrostatic pressure in the tub 2 , The hydrostatic pressure p results from the level of the in the tub 2 training free fleet 7 , In addition, the washing machine includes 1 a measuring device 15 for determining the amount of water filled, eg a water meter or a flow meter. In the case of a flow meter, the amount of water flowed in is calculated in conjunction with a detected filling time. The flow can also be determined by measuring the time to reach a given level height, which corresponds to a certain fixed amount of water. The determination of the amount of water charged, whether at the beginning of a washing program for determining the reference value of the motor drive current or a foam measure after the presence of foam has been detected, allows a more precise implementation of the method according to the invention and in embodiments also a foam measure.

18 means a drain pump for pumping out the wash liquor 7 , 10 means a temperature sensor.

11 means a display device with which the detection of an existing foam and possibly initiated or by a user of the washing machine einleitbaren remedial measures, ie foam measures can be displayed. Moreover, by means of the display device 11 Process parameters, in particular a drainage of a wash program under optimal detergent use and foam avoidance (eg represented by a green light emitting diode) or under non-optimal detergent use and foam generation (eg represented by a red light emitting diode) are displayed.

• (a) Bereitstellung im Laugenbehälter 2 einer waschmittelhaltigen wässrigen Flüssigkeit 7;
• (b) Bestimmung eines Referenzwertes m_ref für die Trommeldrehzahl m der Trommel 3 als Maß für einen schaumlosen Zustand, wobei der Referenzwert m_ref gleich einer einzigen gemessenen Trommeldrehzahl m₁ ist oder gleich einem Mittelwert von mehreren gemessenen Trommeldrehzahlen m_n (n > 1) ist, die ihrerseits jeweils unter einer Referenzbedingung erhalten wurden, nämlich als ein Mittelwert während eines Trommeldrehzeitraumes Δt_n, in dem der Antriebsmotor 5 mit einem vorgegebenen Antriebsstromwert I_A betrieben wird;
• (c) Speicherung von mindestens dem Referenzwert m_ref in der Motor-Trommel-Kontrolleinheit 9;
• (d) Starten einer Waschphase WP mit den Wäschestücken 4 in der im Schritt (a) bereitgestellten wässrigen Flüssigkeit 7;
• (e) Messung während der Waschphase WP von Waschphasentrommeldrehzahlen m_n ^WP (n ≥ 1) unter der Referenzbedingung, indem m_n ^WP jeweils als Mittelwert während des Trommeldrehzeitraumes Δt_n, in dem der Antriebsmotor mit einem vorgegebenen Antriebsstromwert I_A betrieben wird, gemessen wird;
• (f) für den Fall, dass n = 1 ist, Speicherung der Waschphasentrommeldrehzahl m₁ ^WP als Waschphasenwert m^WP der Trommeldrehzahl in der Motor-Trommel-Kontrolleinheit 9 und für den Fall, dass n > 1 ist, Speicherung des durch Mittelung von mehreren gemessenen Waschphasentrommeldrehzahlen m_n ^WP erhaltenen mittleren Waschphasentrommeldrehzahl (m^WP)^med als Waschphasenwert m^WP der Trommeldrehzahl der Trommel 3 in der Motor-Trommel-Kontrolleinheit 9;
• (g) Berechnung des Verhältnisses x = m^WP/m_ref; und
• (h) Feststellung eines vorhandenen Schaumes für den Fall, dass x > a ist, wobei a hier den Wert 1,5 hat.

The implementation of the method according to the invention, in which a presence of foam in a washing phase WP by measuring and analyzing the measured during a drum rotation period .DELTA.t _n drum speed m _{n of} the drum 3 is detected, takes place in washing machine 1 This embodiment is characterized in that in the absence of foam for the drum speed m, a reference value m _{ref is first} measured and set with a subsequently measured in the washing phase WP washing phase drum speed m ^WP ratio, the ratio x = m ^WP / m _ref by comparison with a given for the washing phase WP number a is evaluated in terms of the presence of foam. In this embodiment, the method includes the following steps using a motor drum control unit 9 be performed:

• (a) Provision in the tub 2 a detergent-containing aqueous liquid 7 ;
• (b) Determining a reference value m _ref for the drum speed m of the drum 3 as a measure of a foamless state, wherein the reference value m _{ref is} equal to a single measured drum speed m ₁ or equal to an average of a plurality of measured drum speeds m _n (n> 1), each of which is obtained under a reference condition, namely as an average during a drum rotation period Δt _n , in which the drive motor 5 is operated with a predetermined drive current value I _A ;
• (c) storing at least the reference value m _ref in the motor drum control unit 9 ;
• (D) starting a washing phase WP with the laundry items 4 in the aqueous liquid provided in step (a) 7 ;
• (e) Measurement during the wash phase WP of wash phase drum speeds m _n ^WP (n ≥ 1) under the reference condition by measuring m _n ^WP as an average value during the drum rotation period Δt _n in which the drive motor is operated at a predetermined drive current value I _A ;
• (f) in the case where n = 1, storing the washing phase drum speed m ₁ ^WP as the washing phase value m ^{WP of} the drum speed in the motor-drum control unit 9 and in the event that n> 1, storing the mean wash phase drum speed (m ^WP ) ^med obtained by averaging several measured wash phase drum speeds m _n ^WP as the wash phase value m ^{WP of} the drum speed of the drum 3 in the motor drum control unit 9 ;
• (g) calculating the ratio x = m ^WP / m _ref ; and
• (h) detecting an existing foam in the case where x> a, where a here is 1.5.

Correspondingly, x ≦ a means that no foam or a negligible amount of foam has been formed.

2 shows the course of the drive current value I _A and the drum speed m during two drum rotation periods .DELTA.t _n (n = 1, 2) during step (b) of the method according to the invention, in which a reference value m _ref determined in the foamless state and in the motor-drum control unit is stored.

In the embodiment of 2 two drum rotation periods .DELTA.t _n are shown, where the rotational speeds of two m _n reference measurements are shown here with m _r1 and _r2 m accordingly. The drive current values I _{A are} predetermined and in 2 referred to as I _c1 or I _c2 . While the drive motor is operated, the drum rotation speeds m _r1 and m _r2 as average values during the respective periods of time .DELTA.t _r1 and .DELTA.t _r2 are measured which the drum rotation periods .DELTA.t _n are shorter than, because the measurement or until 3 seconds after start of the drive motor here Only after reaching a steady-state condition.

The in the 2 Therefore, measurement results shown enable the determination of a reference value m _ref on the basis of a single measured drum speed m _r1 or on the basis of an averaging of the two measured drum speeds m _rn (n = 2) each under a reference condition, namely as an average during a drum rotation period Δt _n , during which the drive motor with a predetermined drive _{current value} I _A , here I _c1 or I _{c2 is} driven, in which case shorter drum rotation periods, namely the effective drum rotation periods .DELTA.t _r1 and .DELTA.t _r2 are used.

3 shows the course of the drive current value I _A and the drum speed m during two drum rotating periods Δt _n (n = 1, 2) during step (e) of the method according to the invention, wherein after starting a washing phase washing phase drum speeds m _n ^WP measured the drum and in steps (g) and (h) of the method according to the invention with the reference value m _ref are evaluated for possible detection of foam.

While 2 a reference measurement illustrated, illustrated 3 the case of a measurement for the possible detection of foam in a washing phase WP. Since only other drum speeds are measured in the washing phase WP under otherwise identical reference conditions, in 3 also shown two drum rotation periods .DELTA.t _n, wherein the predetermined drive current values are also referred to herein I _A of the drive motor of the drum I _c1 and I _c2. While the drum is being operated with these drive current values I _{A of} the drive motor, the drum speeds m _n , here m _n ^WP , are measured. Here, the measurement of the drum speeds m _n also takes place only after reaching a steady-state state or 3 seconds after turning on the drum rotation and current measurement. The respective measurement periods Δt _r1 and Δt _r2 are thus also shorter than the actual drum rotation periods Δt _n .

Depending on whether according to 2 a single reference value or an averaged reference value is used will be off 3 either m _r1 , m _r2 or an average value of m _r1 and m _{r2 used} for the comparison with the reference value m _ref and thus the detection of foam.

LIST OF REFERENCE NUMBERS

1

 Washing machine

2

 tub

3

 drum

4

 laundry

5

 drive motor

6

 pressure sensor

7

 aqueous liquid, free liquor, wash liquor

8th

 control device

9

 Motor Drum control unit

10

 temperature sensor

11

 display device

12

 (Detergent) dispensing shell

13

 Supply line to the tub

14

 laundry agitator

15

 Measuring device for determining the amount of water filled

16

 heater

17

 scoop

18

 Pump, drain pump

19

 axis of rotation

20

 Water supply, domestic water network, water supply

21

 (electrically controllable) valve

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 3638498 A1 [0008]
• DE 10234472 A1 [0009]
• DE 102006027197 A1 [0010]
• DE 4104151 A [0015]
• DE 102008028030 A1 [0016]
• DE 102010028614 A1 [0018]
• DE 19738845 A1 [0019]
• EP 0657576 B1 [0020]
• DE 102007042968 A [0021]

Claims (15)

Method for operating a washing machine ( 1 ) with a tub ( 2 ), a drum ( 3 ) for receiving laundry items ( 4 ), a drive motor ( 5 ) for the drum ( 3 ), and a control device ( 8th ), characterized in that a presence of foam in a washing phase WP is detected by measuring and analyzing the drum rotation speed m _n measured during a drum rotation period Δt _n by first measuring a reference value m _ref in the absence of foam for the drum speed m _n and a washing phase drum speed m ^WP subsequently measured in the washing phase WP, the ratio x = m ^WP / m _ref being evaluated by comparison with a number a specified for the washing phase WP with regard to the presence of foam. Method according to claim 1, characterized in that by using a motor drum control unit ( 9 ) the following steps are carried out: (a) provision in the tub ( 2 ) a detergent-containing aqueous liquid ( 7 ); (b) determining a reference value m _ref for the drum speed m _n as a measure of a foamless state, wherein the reference value m _{ref is} equal to a single measured drum speed m ₁ or equal to an average of a plurality of measured drum speeds m _n (n> 1), which in turn were each obtained under a reference condition, namely as an average during a drum rotation period Δt _n , during which the drive motor ( 5 ) is operated with a predetermined drive current value I _A ; (c) storing at least the reference value m _ref in the motor drum control unit ( 9 ); (d) starting a washing phase WP with the laundry items ( 4 ) in the aqueous liquid provided in step (a) ( 7 ); (e) measurement during the wash phase WP of wash phase drum speeds m _n ^WP (n ≥ 1) under the reference condition, in which m _n ^{WP are} each averaged during the drum rotation period Δt _n , during which the drive motor ( 5 ) is measured with a predetermined drive current value I _A , is determined; (f) for the case that n = 1, storing the washing phase the drum speed (m ₁ ^WP as a washing phase value m ^WP in the motor-drum control unit 9 ) and, in the event that n> 1, storing the mean wash phase drum speed (m ^WP ) ^med obtained by averaging several measured wash phase drum speeds m _n ^WP as wash phase value m ^{WP of} the wash phase drum speed m _{n of} the motor drum control unit ( 9 ); (g) calculating the ratio x = m ^WP / m _ref ; and (h) detecting an existing foam in the event that x> a. A method according to claim 2, characterized in that the reference value _ref m measured by averaging at least two washing phase drum speeds m _n (n ≥ 2) is obtained average phase washing drum rotational speed _(n m) ^med. Method according to one of claims 1 to 3, characterized in that the drum speed m _n during the drum rotation period .DELTA.t _{n is} measured only after a predetermined time .DELTA.t _set . Method according to one of claims 1 to 4, characterized in that the drum speed m _n during the drum rotation period .DELTA.t _{n is} measured only when their fluctuation is less than 10% about an average value. Method according to one of claims 1 to 5, characterized in that the reference value m _ref is measured at room temperature. Method according to one of claims 1 to 6, characterized in that the drum rotation period .DELTA.t _{n is} in the range of 10 to 50 sec. Method according to one of claims 1 to 7, characterized in that an existing foam is detected when x is greater than 1.5. Method according to one of claims 1 to 8, characterized in that the drive motor ( 5 ) is stopped when x is greater than an upper limit a _max . Method according to one of claims 1 to 9, characterized in that measures are introduced to reduce the amount of foam when detecting foam. Process according to claim 10, characterized in that the aqueous liquid ( 7 ) is diluted by adding water or by a combination of pumping off aqueous liquid and adding water. A method according to claim 10 or 11, characterized in that after completion of an initiated measure to reduce the amount of foam by repeating step (b), a new reference value m _{ref is} ^{newly determined} for the drum speed m _n . Method according to one of claims 1 to 12, characterized in that a measurement of m ^{WP performed} at the end of a washing phase WP and controlling a rinse phase with respect to a quantity of detected foam. Washing machine ( 1 ) with a tub ( 2 ), a drum ( 3 ) for receiving laundry items ( 4 ), a drive motor ( 5 ) for the drum ( 3 ), and a control device ( 8th ), characterized in that the control device ( 8th ) is arranged to carry out a process for its operation in which a presence of foam in a washing phase WP by measuring and analyzing the drum speed m _{n of} the drum measured during a drum rotation period Δt _n ( 3 ) is detected by first measuring a reference value m _ref in the absence of foam for the drum speed m _n and comparing it with a washing phase drum speed m ^WP measured in the washing phase WP, wherein the ratio x = m ^WP / m _ref by comparison is evaluated with a given for the washing phase number a in terms of the presence of foam. Washing machine according to claim 14, characterized in that it comprises a motor drum control unit ( 9 ), and the control device ( 8th ) is arranged for carrying out a method in which, using the motor-drum control unit ( 9 ) the following steps are carried out: (a) provision in the tub ( 2 ) a detergent-containing aqueous liquid ( 7 ); (b) determining a reference value m _ref for the drum speed m _{n of} the drum ( 3 ) as a measure of a foamless condition, wherein the reference value m _{ref is} equal to a single measured drum speed m ₁ or equal to an average of a plurality of measured drum speeds m _n (n> 1), each of which is obtained under a reference condition, namely a Mean value during a drum rotation period Δt _n during which the drive motor ( 5 ) is operated with a predetermined drive current value I _A ; (c) storing at least the reference value m _ref in the motor drum control unit ( 9 ); (d) starting a washing phase WP with the laundry items ( 4 ) in the aqueous liquid provided in step (a) ( 7 ); (e) measurement during the wash phase WP of wash phase drum speeds m _n ^WP (n ≥ 1) under the reference condition, in which m _n ^{WP are} each averaged during the drum rotation period Δt _n , during which the drive motor ( 5 ) is operated with a predetermined drive current value I _A , is measured; (f) in the case where n = 1, storing the washing phase drum speed m ₁ ^WP as the washing phase value m ^WP in the motor drum control unit ( 9 and, in the event that n> 1, storing the mean wash phase drum speed (m _n ^WP ) ^med obtained by averaging several measured wash phase drum speeds m _n ^WP as the wash phase value m ^{WP of} the wash phase drum speed m _{n of} the motor drum control unit ( 9 ); (g) calculating the ratio x = m ^WP / m _ref ; and (h) detecting an existing foam in the event that x> a.

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