EP0383218B1 - Method to control the rinsing of a programme-controlled washing machine - Google Patents

Method to control the rinsing of a programme-controlled washing machine Download PDF

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Publication number
EP0383218B1
EP0383218B1 EP90102655A EP90102655A EP0383218B1 EP 0383218 B1 EP0383218 B1 EP 0383218B1 EP 90102655 A EP90102655 A EP 90102655A EP 90102655 A EP90102655 A EP 90102655A EP 0383218 B1 EP0383218 B1 EP 0383218B1
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EP
European Patent Office
Prior art keywords
conductivity
rinsing
washing machine
water
measuring cell
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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EP90102655A
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German (de)
French (fr)
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EP0383218A1 (en
Inventor
Georg F. Wagner
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Wagner Georg KG
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Lang Apparatebau GmbH
Wagner Georg KG
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Priority to AT90102655T priority Critical patent/ATE87674T1/en
Publication of EP0383218A1 publication Critical patent/EP0383218A1/en
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    • D—TEXTILES; PAPER
    • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
    • D06F—LAUNDERING, DRYING, IRONING, PRESSING OR FOLDING TEXTILE ARTICLES
    • D06F34/00—Details of control systems for washing machines, washer-dryers or laundry dryers
    • D06F34/14—Arrangements for detecting or measuring specific parameters
    • D06F34/22—Condition of the washing liquid, e.g. turbidity
    • D—TEXTILES; PAPER
    • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
    • D06F—LAUNDERING, DRYING, IRONING, PRESSING OR FOLDING TEXTILE ARTICLES
    • D06F2103/00—Parameters monitored or detected for the control of domestic laundry washing machines, washer-dryers or laundry dryers
    • D06F2103/20—Washing liquid condition, e.g. turbidity
    • D06F2103/22—Content of detergent or additives
    • D—TEXTILES; PAPER
    • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
    • D06F—LAUNDERING, DRYING, IRONING, PRESSING OR FOLDING TEXTILE ARTICLES
    • D06F2105/00—Systems or parameters controlled or affected by the control systems of washing machines, washer-dryers or laundry dryers
    • D06F2105/02—Water supply
    • D—TEXTILES; PAPER
    • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
    • D06F—LAUNDERING, DRYING, IRONING, PRESSING OR FOLDING TEXTILE ARTICLES
    • D06F2105/00—Systems or parameters controlled or affected by the control systems of washing machines, washer-dryers or laundry dryers
    • D06F2105/42—Detergent or additive supply
    • D—TEXTILES; PAPER
    • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
    • D06F—LAUNDERING, DRYING, IRONING, PRESSING OR FOLDING TEXTILE ARTICLES
    • D06F2105/00—Systems or parameters controlled or affected by the control systems of washing machines, washer-dryers or laundry dryers
    • D06F2105/52—Changing sequence of operational steps; Carrying out additional operational steps; Modifying operational steps, e.g. by extending duration of steps
    • D—TEXTILES; PAPER
    • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
    • D06F—LAUNDERING, DRYING, IRONING, PRESSING OR FOLDING TEXTILE ARTICLES
    • D06F2105/00—Systems or parameters controlled or affected by the control systems of washing machines, washer-dryers or laundry dryers
    • D06F2105/62—Stopping or disabling machine operation

Definitions

  • the invention relates to a method of the type specified in the preamble of claim 1 and an apparatus for performing the method.
  • the difference value of the specific conductivities is set to a very small value of a few microsiemens.
  • the conductivity measurement must be carried out with extremely high accuracy so that the shortfall in this small difference value can be determined. If the conductivity measuring cell is arranged in the machine room, it is in the moving rinsing water, which has no homogeneous conductivity distribution. The measured conductivity fluctuates with a relatively large amplitude. These amplitude fluctuations are considerably larger than the difference value, the undershoot of which is to be measured. This is the reason why the known method does not provide a sufficient criterion for ending the rinsing process.
  • the reference value is briefly undershot while the rinse water as a whole still has a higher conductivity, so that the rinsing process is terminated too early, and it may also happen that the limit value is not undershot at all, so that the rinse is running too long.
  • DE-A-34 24 711 discloses a method for regulating a cleaning system, in which washing liquid is continuously passed through the cleaning system. There is a conductivity measuring cell in the inlet and one in the outlet. The difference between the two conductivity signals is compared with a predetermined limit value and the cleaning phase is ended when the inlet and outlet have essentially the same conductivity values. Such a method is not suitable for monitoring the washing processes of a washing machine because these washing processes are carried out at intervals and not in continuous operation. In addition, conductivity differences cannot be measured with sufficient certainty in the known method.
  • the invention is based on the object of specifying a method which is suitable for controlling the rinsing processes of a washing machine with high accuracy and for indicating the completion of the rinsing process with a very low residual concentration of the detergent.
  • the conductance is measured only when the water flow is at a standstill.
  • a sufficiently precise and uniform measurement which leads to a representative result, is only possible when the water flow stops.
  • the flow sweeping along a conductivity measuring cell causes a strongly varying conductivity signal simply because of the flow turbulence.
  • the conductivity of the rinsing water running off after a rinsing process varies greatly due to the different lye concentration.
  • the rinse water that runs off first has a relatively low residual alkalinity, while the alkalinity and thus the conductivity increases towards the end of the drain, when the water coming from the depths of the fabric of the material to be washed is pumped out.
  • measurements are only carried out when the rinsing water is at a standstill, and in each section of the drain line in which the measurement is carried out is the rinsing water that came from the depths of the tissue and that was the last to leave the washing machine room during pumping.
  • a decision is made as to whether a further rinsing process is necessary and, if necessary, the amount of fresh water with which the new rinsing process must be carried out.
  • the measurement during a break also has the advantage of precisely determining the temperature for the calculation of the temperature coefficient. This is important because there are cold and warm rinsing processes.
  • the method according to the invention optimizes the rinsing quality and the washing result and minimizes the consumption values for electricity, water and time.
  • the differential conductivity measured value can shorten a rinsing process if the measured value means that there is no longer any need for a longer or further rinse provided in the program.
  • the differential conductance should intervene directly in the program sequence control for the rinsing and spinning process.
  • An electrical conductivity measuring cell is arranged in the water inlet, since the conductivity value of the inlet water is also within the same water supply due to seasonal or technical circumstances can fluctuate greatly, which could become a significant source of error if the desired conductivity measured value, which is correlated to the desired residual alkalinity, was compared only with the measured conductivity value measured by the measuring cell in the water outlet and not with the differential measured conductivity value from the water inlet and water outlet measuring cells.
  • the arrangement of a further conductivity measuring cell in the washing machine room enables the concentration there to be monitored and thus a control of the metering that has taken place and a control of the foam development in the lye room.
  • the concentration of the wash liquor can be determined with the conductivity measuring cell in the washing machine room, since the detergents used today in the commercial and small-scale sector but also in the household sector bring about an at least similar conductivity value for the wash liquor.
  • an over- or under-dosing can be determined if the measured conductivity value deviates from the usual or the program specification, and can be triggered as a result of re-dosing or the inflow of fresh water.
  • the determined foam development can then be influenced by intervening in the program sequence, such as stopping the washing drum, lowering the temperature, etc.
  • this conductivity measuring cell acting as a foam detector or sensor, for example, the escape of foam from the induction bowl is prevented and excessive foam development, which leads to a poorer washing result, can be counteracted.
  • the washing machine designated overall by 1, has an inlet hose 2 for fresh water, which is attached to the water inlet of the washing machine by means of a coupling 3.
  • a first conductivity measuring cell 4 with a temperature sensor is arranged in the inlet hose 2.
  • a valve device 6 composed of solenoid valves is arranged in the water inlet on the washing machine side to the detergent dispensing chamber 5.
  • the detergent dispensing chamber 5 is connected to the washing machine room 7, in which a washing drum 8 is arranged, via a pipeline 9.
  • the lower conductivity measuring cell is located at the normal level 11, which corresponds to the suds level in normal washing programs.
  • the upper one of the conductivity measuring cells 10 is located at the level of the high level 12 and the wool level 13, which can be achieved with wool washing programs or washing programs with a high suds level.
  • another pipe 14 leads to an emptying pump 15 provided with a fluff filter.
  • another pipe 16 branches off from the pipe 14, at the end of which a pressure switch 17 is attached.
  • a pipeline 18 branches off from the pipeline 14 and leads to an emergency drain 19.
  • the drain line 20 follows, which forms the water drain from the washing machine to form a siphon 21.
  • another line 22 leading to the detergent dispensing chamber 5 branches off, which is designed as a vent 23.
  • a further conductivity measuring cell 24 with a temperature sensor is arranged in the drain hose 20.
  • the conductivity measuring cells 4 and 24 have the same electrical cell constants and conductivity values. With the conductivity measuring cell 4 the specific electrical conductivity of the water entering the washing machine 1 is measured and with the conductivity measuring cell 24 the specific electrical conductivity of the water pumped out of the washing machine 1 is measured in each case in a temperature-compensated manner.
  • the measuring cell 24 is arranged in the section 20a of the drain line 20, in which the residual water remains after the pumping has ended, so that it is permanently below the liquid level, which is provided in the lines 20 and 16 with the reference number 25, and thus is constantly on Liquid pressure is present and wetting takes place with liquid. In particular, an arrangement in a calmed down pump sump has proven to be advantageous.
  • the measuring cell 4 is arranged in the pressurized side of the water inlet, upstream of the program-controlled valve device 6, so that a liquid pressure is constantly present at this measuring cell and wetting of the measuring cell with liquid is constantly ensured.
  • the signal from the measuring cell 4 is only evaluated when the valve device 6 is shut off.
  • the conductivity measurements are carried out in the state without liquid flow at the end of individual program steps and this measured value is stored until the next program step.
  • This measured value is assumed to be the "true conductance” if it shows a drift below 2 ⁇ S / cm after several individual measurements.
  • the temperature sensor is then in the steady state.
  • the differential conductivity measured value is calculated, taking into account the special temperature compensation values for the inlet and outlet water, and this value is fed to the control electronics of the washing machine as a signal for the program control. This can result, for example, in a repetition or termination of the pending or just carried out rinsing or spinning process.
  • the measured values delivered by the measuring cells 4 and 24 or the differential conductance are individually evaluated in the control electronics of the washing machine depending on the washing program set or additionally on the current program step within the washing process and with characteristic values which are stored in the washing machine control system to trigger certain switching processes. compared.
  • the program sequence control can then be influenced to change the amount of water flowing into the washing machine or, for example, also the spin speed of the washing machine drum.
  • a lack of the differential conductivity measurement signal is evaluated by the control electronics as a disturbance. With this e.g. cause the program to be interrupted if there is a lack of water or a lack of detergent.
  • the arranged in the washing machine room 7 conductivity measuring cells 10 can be designed so that the specific electrical conductivity measured there and the respective temperature coefficient with those in the Individual washing cycles of the values of a particular detergent that are usually present and stored in the control electronics can be compared.
  • Both the conductivity measuring cell 10 and the conductivity measuring cell 24 can also be used to control a metering device (not shown in more detail) in order to achieve a concentration of detergent substance in the washing machine room that is dependent on the type of washing and the washing program.
  • the measuring cells in the washing machine room 7 can also be used for flow evaluation, for example the display of lack of water, and for determining excess or. Lower concentrations of detergent in the wash liquor can be used.
  • the movement of the washing drum can also be controlled by rhythmically flooding and exposing the conductivity measuring cell.
  • the foam development in the washing machine room 7 can also be measured via the signal evaluation of the electrical conductivity measuring cells 10 installed there and used for a direct intervention in the program sequence control to reduce or eliminate the foam development, for example by a temporary machine stop, a lowering of the washing liquor temperature, a change in the drum speed, a change in the interval times, the addition of fresh water, etc. causes.
  • the electrical conductivity measuring cell 4 in the water inlet is provided so that there are also fluctuations in the conductivity value of the inlet water, which also occurs within the same water supply due to seasonal changes or may fluctuate greatly due to technical reasons, is correctly recorded in each case.
  • the measuring cell 4 is provided with a fast-acting temperature sensor. Furthermore, it must be possible to set a temperature coefficient so that the measurement error does not become too great given the low conductivity values typically found in the microsiemens range, for example 200 to 1200 ⁇ S.
  • the measuring cell 4 is arranged in the pressurized flow in front of the water inlet solenoid valves 6 and is therefore subject to long-term stable measuring conditions.
  • the measuring cell 24 is also temperature-compensated in order to be able to compensate for the different washing liquor temperatures in different types of laundry and washing programs with regard to their influence on the differential conductivity measured value.
  • the temperature coefficient is preferably set to the typical values of a highly dilute alkaline, aqueous liquid which is similar to the water value. Because of its arrangement in the area of the siphon 21, the measuring cell 24 is also subjected to long-term stable measuring conditions, in particular constant wetting of the measuring cell.
  • This permanent wetting of the flow measuring cells has the advantage that the inertia of the temperature sensor is eliminated, because in any case, in the context of rapidly running washing programs, the time required for the temperature sensor to settle warmly given is. This settling of the temperature sensor is a prerequisite for correct temperature compensation and this in turn is a prerequisite for correct measurement and formation of a difference value. Without the arrangement, a reliable measured value cannot be determined if it is to be accurate in the range of a few microsiemens.
  • the two measuring cells 4 and 24 are arranged as simple intermediate pieces in the lines 2 and 20.
  • Their measuring cell geometry corresponds to the requirements of a low cell constant, e.g. 1.0, and the hygienic requirements with regard to the lowest possible deposits.
  • the temperature sensors have a time constant in the lower second range, so that the duration of the measurement value falsification is kept as short as possible due to the settling to the correct temperature value. This run-in time is hidden from the measurement.
  • the conductivity measured values determined by means of the measuring cells 4 and 24 are processed either analog or digital in a differential arithmetic circuit and linked to switching points of the program sequence control.
  • a microprocessor with permanent memory for the measured values should expediently be provided so that the last operating state can be recorded in the event of a power failure.
  • the control electronics are used to assign various switching points of the program sequence control to the curve profile of the differential conductivity measured value which are selected and activated as a function of the programmed type of laundry and which control the course of the washing program within the program step or washing cycle which is currently pending.
  • the water inflow is to be controlled on the basis of the measured values determined, as are the time and number of alkali dilution and mixing processes, and in particular the duration and number of revolutions of the intermediate spin.
  • the centrifuged water pumped out last is decisive for the final quality of the condition-dependent rinsing. If the final value still deviates from the norm despite previous rinsing optimization, a further rinsing and spinning process can be triggered.
  • the signals from the measuring cells 4 and 24 can also be used for fault reports. For example, an empty water supply hose or heavily contaminated water can be reported by means of cell 4 if either no measured value signal or a signal that is above a limit value is measured.
  • the measuring cell 24 can also be used to determine whether the wash liquor is under-concentrated. Faulty operation of the drain pump can also be determined with this measuring cell, since the transition from one wash cycle to a next wash cycle is usually also associated with a change in the electrical conductivity in the wash liquor or the wash water. If a change in the electrical conductivity cannot be determined during such a washing cycle change, it can be concluded from this that a defective drain pump or a blocked lint filter.
  • the conductivity measuring cells 10 in the washing machine room 7 serve to determine the concentration of detergent in the wash liquor and to control the development of foam. Since one is particularly in the commercial and small trade Area, but also for household washing machines, it can be assumed that the same detergents are usually used, which produce approximately the same conductivity values in the wash liquor, with these measuring cells an overdosing or underdosing, which cause a conductivity in the washing liquor deviating from the standard value, can be determined. This deviation can be processed in the control electronics to either add more detergent or to supply fresh water.
  • one of the measuring cells 10 is arranged in the area of the normal level 11 in the washing machine room 7, this can be used as an electrical foam detector or sensor.
  • the result of the foam formation is that the fill level drops below the level detected by the measuring cell 10 and the liquid is partially distributed in the foam bubbles.
  • a conductivity measurement value can only be determined from the conductivity measuring cell when foam bubbles are present on the cell.
  • the foam bubbles between the electrodes of each measuring cell cause a short current flow when there is foam between the electrodes, which is immediately interrupted when the foam runs out of the measuring cell. Electrical signals therefore fluctuate only sporadically and within a very short time.
  • the rate of change and the amount of change are characteristic of the foam and certain states of the foam in the sense of a signal curve evaluation, for example a Fourier transformation. This can be used to detect the state of foam in the washing machine room 7.
  • the electrical method of foam detection is quicker in terms of its response behavior than the differential pressure measurement methods that have been customary up to now, and it also reacts much earlier than, for example, a pressure sensor. If the development of foam has been determined by means of the conductivity measuring cells 10, the electrical signals in the control electronics can be used to influence the program sequence control and can be implemented, for example, in stopping the rotational movement of the washing drum 8 or in lowering the washing temperature.
  • the foam development for different alkalis or fill level levels can be detected or ascertained.
  • the response threshold of the foam detection is variable, so that it can be taken into account that different detergents and washing programs as well as differently soiled laundry have different foaming effects.
  • These measuring cells 10 which are designed as foam detectors, prevent foam from escaping from the detergent dispensing chamber and thus prevent water damage in and outside the device. This can also improve the washing result, since excessive foaming leads to a significant decrease in the effectiveness of the washing mechanism and thus to a poorer washing result.
  • Curve a shows the successive prewash VW, main wash HW and rinse processes SP1, SP2 and SP3, the speed n of the drum 8 being indicated along the ordinate.
  • Diagram b) shows the quantities of water Q that are contained in the washing machine room 7 in the various washing and rinsing processes in chronological assignment to diagram a).
  • the sloping flanks indicate the times of water intake or water drainage.
  • Diagram c) shows the blocking times 30 in which the evaluation of the signal from the measuring cell 24 is suppressed. These are the times when the pump 15 pumps water out of the machine room 7.
  • Diagram d) shows the conductance difference ⁇ k, that is to say the difference between the conductance measured at measuring cell 24 and the reference conductance.
  • the reference conductance is the conductance of the fresh water measured and stored by the measuring cell 4.
  • the predetermined dimension ⁇ k g of the differential conductance, at which no further rinsing process is required, is 50 ⁇ S / cm in the present exemplary embodiment.
  • the conductivity values are specific conductivities.
  • the conductivity of the water running off the main washing process HW is very high because of the high detergent content and is, for example, 8000 ⁇ S / cm. This value is not entered in Fig. 2d).
  • an irregular, strongly fluctuating signal 31 is produced on the measuring cell 24 while the rinsing water is being pumped out, the conductivity dropping sharply at the beginning of the pumping and then increasing when the residual water coming from the depths of the tissue reaches the measuring cell .
  • the vibrating signal 31 falls within the range of a blocking time 30 and is not evaluated.
  • the residual water is in the section 20a and after a settling time a of about one second after the pumping has ended, the conductivity is measured in point 32 or the conductivity signal supplied by the measuring cell 24 is evaluated. If the differential conductance determined in point 32 is still above the dimension ⁇ k g , the further rinsing process SP2 is then carried out.

Abstract

The washing machine is equipped with a conductivity measuring cell (24) which determines the electrolyte content of the pumped-off rinsing water, so that a decision can be made as to whether a further rinsing operation is necessary. The measuring cell (24) is arranged in a portion (20a) of the run-off line (20), in which there is still residual water from the rinsing operation after the pumping off. The conductivity measurement is carried out with the rinsing water at a standstill. The conductance of the fresh water which is fed to the washing machine and which has been measured by a further measuring cell (4), likewise with the water at a standstill, is used as reference conductance. <IMAGE>

Description

Die Erfindung betrifft ein Verfahren der im Oberbegriff des Patentanspruchs 1 angegebenen Art sowie eine Vorrichtung zur Durchführung des Verfahrens.The invention relates to a method of the type specified in the preamble of claim 1 and an apparatus for performing the method.

Aus DE-OS 28 54 148 ist es bekannt, in dem die Trommel enthaltenden Waschmaschinenraum eine Leitfähigkeits-Meßzelle anzuordnen, die die Leitfähigkeit des Spülwassers zu Beginn eines Spülvorganges mißt und die während des Spülvorgangs weitere Leitfähigkeitsmessungen vornimmt. Die elektrische Leitfähigkeit des Spülwasser hängt von dem Grad der Verschmutzung und von dem verwendeten Waschmittel ab. Bei dem bekannten Verfahren wird die Leitfähigkeit des einlaufenden und des auslaufenden Spülwassers mit derselben Leitfähigkeits-Meßzelle gemessen. Der Leitfähigkeitswert des einlaufenden Spülwassers wird als Referenzwert gespeichert und mit diesem Referenzwert die jeweils aktuelle Leitfähigkeit verglichen. Wenn die Leitfähigkeitsdifferenz einen vorbestimmten Wert unterschreitet, wird die Spülung beendet.From DE-OS 28 54 148 it is known to arrange a conductivity measuring cell in the washing machine room containing the drum, which measures the conductivity of the rinsing water at the beginning of a rinsing process and which carries out further conductivity measurements during the rinsing process. The electrical conductivity of the rinsing water depends on the degree of soiling and the detergent used. In the known method, the conductivity of the incoming and outgoing rinsing water is measured with the same conductivity measuring cell. The conductivity value of the incoming rinse water is saved as a reference value and compared the current conductivity with this reference value. If the conductivity difference falls below a predetermined value, the flushing is ended.

Da die Laugenkonzentration am Ende der Spülung nur äußerst gering sein darf, wird der Differenzwert der spezifischen Leitfähigkeiten auf einen sehr kleinen Wert von einigen Mikrosiemens festgelegt. Damit die Unterschreitung dieses geringen Differenzwertes festgestellt werden kann, muß die Leitfähigkeitsmessung mit extrem hoher Genauigkeit durchgeführt werden. Wenn die Leitfähigkeits-Meßzelle im Maschinenraum angeordnet ist, befindet sie sich in dem bewegten Spülwasser, das keine homogene Leitfähigkeitsverteilung aufweist. Die gemessene Leitfähigkeit schwankt mit relativ großer Amplitude. Diese Amplitudenschwankungen sind erheblich größer als der Differenzwert, dessen Unterschreitung gemessen werden soll. Dies ist der Grund dafür, daß das bekannte Verfahren kein hinreichendes Kriterium für die Beendigung des Spülvorgangs liefert. Einerseits kann es vorkommen, daß der Referenzwert kurzzeitig unterschritten wird, während das Spülwasser insgesamt aber noch einen größeren Leitwert hat, so daß der Spülvorgang zu früh abgebrochen wird, und ferner kann es vorkommen, daß eine Unterschreitung des Grenzwertes überhaupt nicht festgestellt wird, so daß die Spülung viel zu lange läuft.Since the alkali concentration at the end of the rinse must be extremely low, the difference value of the specific conductivities is set to a very small value of a few microsiemens. The conductivity measurement must be carried out with extremely high accuracy so that the shortfall in this small difference value can be determined. If the conductivity measuring cell is arranged in the machine room, it is in the moving rinsing water, which has no homogeneous conductivity distribution. The measured conductivity fluctuates with a relatively large amplitude. These amplitude fluctuations are considerably larger than the difference value, the undershoot of which is to be measured. This is the reason why the known method does not provide a sufficient criterion for ending the rinsing process. On the one hand, it may happen that the reference value is briefly undershot while the rinse water as a whole still has a higher conductivity, so that the rinsing process is terminated too early, and it may also happen that the limit value is not undershot at all, so that the rinse is running too long.

Aus DE-A-34 24 711 ist ein Verfahren zum Regeln einer Reinigungsanlage bekannt, bei dem die Reinigungsanlage kontinuierlich von Waschflüssigkeit durchlaufen wird. Im Einlaß und im Auslaß befindet sich jeweils eine Leitfähigkeits-Meßzelle. Die Differenz der beiden Leitfähigkeitssignale wird mit einem vorbestimmten Grenzwert verglichen und die Reinigungsphase wird beendet, wenn am Einlauf und am Auslauf im wesentlichen gleiche Leitfähigkeitswerte vorliegen. Ein solches Verfahren ist für die Überwachung der Spülvorgänge einer Waschmaschine nicht geeignet, weil diese Spülvorgänge intervallmäßig und nicht im Durchlaufbetrieb ausgeführt werden. Außerdem lassen sich bei dem bekannten Verfahren ebenfalls Leitfähigkeitsdifferenzen nicht mit hinreichender Sicherheit messen.DE-A-34 24 711 discloses a method for regulating a cleaning system, in which washing liquid is continuously passed through the cleaning system. There is a conductivity measuring cell in the inlet and one in the outlet. The difference between the two conductivity signals is compared with a predetermined limit value and the cleaning phase is ended when the inlet and outlet have essentially the same conductivity values. Such a method is not suitable for monitoring the washing processes of a washing machine because these washing processes are carried out at intervals and not in continuous operation. In addition, conductivity differences cannot be measured with sufficient certainty in the known method.

Der Erfindung liegt die Aufgabe zugrunde, ein Verfahren anzugeben, das geeignet ist, die Spülvorgänge einer Waschmaschine mit hoher Genauigkeit zu steuern und die Beendigung des Spülvorganges bei sehr geringer Restkonzentration des Waschmittels anzugeben.The invention is based on the object of specifying a method which is suitable for controlling the rinsing processes of a washing machine with high accuracy and for indicating the completion of the rinsing process with a very low residual concentration of the detergent.

Die Lösung dieser Aufgabe erfolgt erfindungsgemäß mit den im Patentanspruch 1 angegebenen Merkmalen.This object is achieved according to the invention with the features specified in claim 1.

Bei dem erfindungsgemäßen Verfahren erfolgt die Leitwertmessung ausschließlich bei stillstehender Wasserströmung. Nur bei Stillstand der Wasserströmung ist eine hinreichend genaue und gleichförmige Messung möglich, die zu einem repräsentativen Ergebnis führt. Die an einer Leitfähigkeits-Meßzelle entlangstreichende Strömung verursacht allein schon aufgrund der Strömungsturbulenzen ein stark variierendes Leitfähigkeitssignal. Hinzu kommt, daß die Leitfähigkeit des nach einem Spülvorgang ablaufenden Spülwassers wegen der unterschiedlichen Laugenkonzentration stark variiert. Das zuerst ablaufende Spülwasser hat eine relativ geringe Restalkalität, während sich die Alkalität und somit die Leitfähigkeit gegen Ende des Ablaufens erhöht, wenn das aus den Tiefen des Gewebes des zu waschenden Materials kommende Wasser abgepumpt wird. Bei der erfindungsgemäßen Leitwertmessung wird immer nur bei stehendem Spülwasser gemessen, und zwar befindet sich in demjenigen Abschnitt der Ablaufleitung, in dem die Messung durchgeführt wird, jeweils das aus den Tiefen des Gewebes kommende Spülwasser, das den Waschmaschinenraum beim Abpumpen als letztes verlassen hat. In Abhängigkeit von dem gemessenen Leitwert wird entschieden, ob ein weiterer Spülvorgang erforderlich ist, und ggf. auch mit welcher Frischwassermenge der neue Spülvorgang ausgeführt werden muß.In the method according to the invention, the conductance is measured only when the water flow is at a standstill. A sufficiently precise and uniform measurement, which leads to a representative result, is only possible when the water flow stops. The flow sweeping along a conductivity measuring cell causes a strongly varying conductivity signal simply because of the flow turbulence. In addition, the conductivity of the rinsing water running off after a rinsing process varies greatly due to the different lye concentration. The rinse water that runs off first has a relatively low residual alkalinity, while the alkalinity and thus the conductivity increases towards the end of the drain, when the water coming from the depths of the fabric of the material to be washed is pumped out. In the conductance measurement according to the invention, measurements are only carried out when the rinsing water is at a standstill, and in each section of the drain line in which the measurement is carried out is the rinsing water that came from the depths of the tissue and that was the last to leave the washing machine room during pumping. Depending on the measured conductance, a decision is made as to whether a further rinsing process is necessary and, if necessary, the amount of fresh water with which the new rinsing process must be carried out.

Die Messung in einer Ruhepause hat auch den Vorteil, die Temperatur für die Errechnung des Temperaturkoeffizienten exakt zu bestimmen. Dies ist deshalb wichtig, weil es kalte und warme Spülvorgänge gibt.The measurement during a break also has the advantage of precisely determining the temperature for the calculation of the temperature coefficient. This is important because there are cold and warm rinsing processes.

Mit dem erfindungsgemäßen Verfahren wird eine Optimierung der Spülqualität und des Waschergebnisses sowie eine Minimierung der Verbrauchswerte an Strom, Wasser und Zeit erzielt. Beispielsweise kann durch den Differenzleitmeßwert eine Verkürzung eines Spülvorganges bewirkt werden, wenn sich aufgrund des Meßwertes keine Notwendigkeit mehr für eine im Programm vorgesehene längere oder weitere Spülung ergibt. Insbesondere soll bei dem erfindungsgemäßen Verfahren der Differenzleitwert direkt in die Programmablaufsteuerung für den Spül- und Schleudervorgang regelnd eingreifen.The method according to the invention optimizes the rinsing quality and the washing result and minimizes the consumption values for electricity, water and time. For example, the differential conductivity measured value can shorten a rinsing process if the measured value means that there is no longer any need for a longer or further rinse provided in the program. In particular, in the method according to the invention, the differential conductance should intervene directly in the program sequence control for the rinsing and spinning process.

Im Wasserzulauf ist eine elektrische Leitfähigkeits-Meßzelle angeordnet, da auch innerhalb der gleichen Wasserversorgung durch jahreszeitliche oder technisch bedingte Umstände der Leitfähigkeitswert des Zulaufwassers stark schwanken kann, was zu einer bedeutenden Fehlerquelle werden könnte, wenn der in Korrelation zu der gewünschten Restalkalität stehende Soll-Leitfähigkeitsmeßwert nur mit dem durch die Meßzelle im Wasserablauf gemessenen Leitfähigkeitsmeßwert und nicht mit dem Differenzleitfähigkeitsmeßwert aus Wasserzulauf-und Wasserablaufmeßzelle verglichen würde.An electrical conductivity measuring cell is arranged in the water inlet, since the conductivity value of the inlet water is also within the same water supply due to seasonal or technical circumstances can fluctuate greatly, which could become a significant source of error if the desired conductivity measured value, which is correlated to the desired residual alkalinity, was compared only with the measured conductivity value measured by the measuring cell in the water outlet and not with the differential measured conductivity value from the water inlet and water outlet measuring cells.

Die Anordnung einer weiteren Leitfähigkeits-Meßzelle im Waschmaschinenraum ermöglicht die Überwachung der dortigen Konzentration und damit eine Kontrolle der erfolgten Dosierung sowie eine Kontrolle der Schaumentwicklung im Laugenraum.The arrangement of a further conductivity measuring cell in the washing machine room enables the concentration there to be monitored and thus a control of the metering that has taken place and a control of the foam development in the lye room.

Mit der Leitfähigkeits-Meßzelle im Waschmaschinenraum läßt sich die Konzentration der Waschlauge bestimmen, da die heute im gewerblichen und kleingewerblichen Bereich aber auch im Haushaltsbereich eingesetzten Waschmittel einen zumindest ähnlichen Leitfähigkeitswert der Waschlauge bewirken. Mit der Leitfähigkeits-Meßzelle im Waschmaschinenraum läßt sich somit eine Über- oder Unterdosierung feststellen, wenn der gemessene Leitfähigkeitswert vom Üblichen oder von der Programmvorgabe abweicht, und kann infolge einer Nachdosierung oder der Zulauf von Frischwasser ausgelöst werden.The concentration of the wash liquor can be determined with the conductivity measuring cell in the washing machine room, since the detergents used today in the commercial and small-scale sector but also in the household sector bring about an at least similar conductivity value for the wash liquor. With the conductivity measuring cell in the washing machine room, an over- or under-dosing can be determined if the measured conductivity value deviates from the usual or the program specification, and can be triggered as a result of re-dosing or the inflow of fresh water.

Durch den Einbau einer Leitfähigkeits-Meßzelle im Waschmaschinenraum knapp unterhalb oder oberhalb der Normalniveauhöhe der Waschlauge läßt sich die Schaumbildung der Waschlauge kontrollieren. Hierbei wird der Effekt ausgenutzt, daß Schaumbläschen entstehen und zerplatzen und dabei kurzfristig eine elektrische Verbindung zwischen den Elektroden von Leitfähigkeits-Meßzellen und damit einen kurzen Stromfluß bewirken, welcher anschließend, sobald der Schaum die Meßzelle verläßt, wieder unterbrochen wird. Diese durch den Stromfluß bewirkten Signale schwanken innerhalb sehr kurzer Zeit, wobei die Änderungsgeschwindigkeit und die Änderungshöhe, bezogen auf den absoluten Signalpegel der Lauge, im Sinne einer Signalkurvenauswertung bzw. einer Fouriertransformation für den Schaum und bestimmte Zustandsformen des Schaumes charakterisierend sind. Diese elektrische bzw. elektrometrische Methode der Schaumerkennung ist im Ansprechverhalten schneller als die bisherigen Differenzdruckmeßverfahren und reagiert auch wesentlich frühzeitiger als eine Druckmeßdose. Die festgestellte Schaumentwicklung läßt sich dann durch Eingriffe in den Programmablauf, wie z.B. Anhalten der Waschtrommel, Erniedrigung der Temperatur, etc. beeinflussen. Mit Hilfe dieser als Schaumdetektor bzw. -sensor wirkenden Leitfähigkeits-Meßzelle wird beispielsweise das Austreten von Schaum aus der Einspülschale verhindert und kann einer zu starken Schaumentwicklung, die zu einem schlechteren Waschergebnis führt, entgegengewirkt werden.By installing a conductivity measuring cell in the washing machine room just below or above the normal level of the washing liquor, the foaming of the washing liquor can be checked. The effect is exploited here that foam bubbles form and burst and in the process briefly cause an electrical connection between the electrodes of conductivity measuring cells and thus a short current flow, which is then interrupted as soon as the foam leaves the measuring cell. These signals caused by the current flow fluctuate within a very short time, the rate of change and the amount of change, based on the absolute signal level of the lye, being characteristic of a signal curve evaluation or a Fourier transformation for the foam and certain states of the foam. This electrical or electrometric method of foam detection is faster in response than the previous differential pressure measuring method and also reacts much earlier than a pressure cell. The determined foam development can then be influenced by intervening in the program sequence, such as stopping the washing drum, lowering the temperature, etc. With the help of this conductivity measuring cell acting as a foam detector or sensor, for example, the escape of foam from the induction bowl is prevented and excessive foam development, which leads to a poorer washing result, can be counteracted.

Im folgenden wird ein Ausführungsbeispiel der Erfindung anhand der Zeichnungen näher erläutert.In the following an embodiment of the invention is explained in more detail with reference to the drawings.

Es zeigen:

Fig. 1
eine schematische Darstellung der wasserführenden Elemente der Waschmaschine mit den eingebauten Leitfähigkeits-Meßzellen und
Fig. 2
ein Diagramm der zeitlichen Abläufe der einzelnen Wasch- und Spülvorgänge sowie die von der Meßzelle nach den Spülvorgängen gemessenen Leitfähigkeiten.
Show it:
Fig. 1
is a schematic representation of the water-carrying elements of the washing machine with the built-in conductivity measuring cells and
Fig. 2
a diagram of the time sequences of the individual washing and rinsing processes and the conductivities measured by the measuring cell after the rinsing processes.

Die insgesamt mit 1 bezeichnete Waschmaschine weist einen Zulaufschlauch 2 für Frischwasser auf, der mittels einer Kupplung 3 an dem Wasserzulauf der Waschmaschine angebracht ist. In dem Zulaufschlauch 2 ist eine erste Leitfähigkeits-Meßzelle 4 mit Temperaturfühler angeordnet. In dem waschmaschinenseitigen Wasserzulauf zur Waschmitteleinspülkammer 5 ist eine Ventilvorrichtung 6 aus Magnetventilen angeordnet. Die Waschmitteleinspülkammer 5 steht mit dem Waschmaschinenraum 7, in welchem eine Waschtrommel 8 angeordnet ist, über eine Rohrleitung 9 in Verbindung. In dem Waschmaschinenraum 7 sind zwei weitere, übereinander angeordnete Leitfähigkeits-Meßzellen 10 mit Temperaturfühler angebracht. Dabei befindet sich die untere Leitfähigkeits-Meßzelle in Höhe des Normalniveaus 11, welches dem Laugenstand bei normalen Waschprogrammen entspricht. Die obere der Leitfähigkeits-Meßzellen 10 befindet sich in Höhe des Hochniveaus 12 und des Wollniveaus 13, welche bei Wollwaschprogrammen bzw. Waschprogrammen mit hohem Laugenstand erreicht werden. Unterhalb des Waschmaschinenraums führt eine weitere Rohrleitung 14 zu einer mit einem Flusensieb versehenen Entleerungspumpe 15. Kurz unterhalb des Waschmaschinenraums 7 zweigt von der Rohrleitung 14 eine weitere Leitung 16 ab, an deren Ende ein Druckwächter 17 angebracht ist. Weiterhin zweigt von der Rohrleitung 14 noch eine Rohrleitung 18 ab, die zu einer Notentleerung 19 führt. In Fließrichtung hinter der Entleerungspumpe 15 schließt sich die Ablaufleitung 20 an, die unter Bildung eines Siphons 21 den Wasserablauf aus der Waschmaschine darstellt. Im Scheitelpunkt des Siphons 21 zweigt eine weitere zur Waschmitteleinspülkammer 5 führende Leitung 22 ab, welche als Entlüftung 23 ausgebildet ist. Zwischen Entleerungspumpe 15 und Siphon 21 ist im Entleerungsschlauch 20 eine weitere Leitfähigkeits-Meßzelle 24 mit Temperaturfühler angeordnet.The washing machine, designated overall by 1, has an inlet hose 2 for fresh water, which is attached to the water inlet of the washing machine by means of a coupling 3. A first conductivity measuring cell 4 with a temperature sensor is arranged in the inlet hose 2. A valve device 6 composed of solenoid valves is arranged in the water inlet on the washing machine side to the detergent dispensing chamber 5. The detergent dispensing chamber 5 is connected to the washing machine room 7, in which a washing drum 8 is arranged, via a pipeline 9. In the washing machine room 7 there are two further conductivity measuring cells 10 arranged one above the other with a temperature sensor. The lower conductivity measuring cell is located at the normal level 11, which corresponds to the suds level in normal washing programs. The upper one of the conductivity measuring cells 10 is located at the level of the high level 12 and the wool level 13, which can be achieved with wool washing programs or washing programs with a high suds level. Below the washing machine room, another pipe 14 leads to an emptying pump 15 provided with a fluff filter. Shortly below the washing machine room 7, another pipe 16 branches off from the pipe 14, at the end of which a pressure switch 17 is attached. Furthermore, a pipeline 18 branches off from the pipeline 14 and leads to an emergency drain 19. In the direction of flow behind the drain pump 15, the drain line 20 follows, which forms the water drain from the washing machine to form a siphon 21. At the apex of the siphon 21, another line 22 leading to the detergent dispensing chamber 5 branches off, which is designed as a vent 23. Between drain pump 15 and siphon 21 a further conductivity measuring cell 24 with a temperature sensor is arranged in the drain hose 20.

Die Leitfähigkeits-Meßzellen 4 und 24 haben gleiche elektrische Zellkonstanten und Leitwertkennlinien. Mit der Leitfähigkeits-Meßzelle 4 wird die spezifische elektrische Leitfähigkeit des in die Waschmaschine 1 einlaufenden Wassers und mit der Leitfähigkeits-Meßzelle 24 wird die spezifische elektrische Leitfähigkeit des aus der Waschmaschine 1 abgepumpten Wasser jeweils temperaturkompensiert gemessen. Die Meßzelle 24 ist in dem Abschnitt 20a der Ablaufleitung 20 angeordnet, in dem nach Beendigung des Abpumpens das Restwasser stehenbleibt, so daß sie permanent unterhalb des Flüssigkeitsspiegels, welcher in den Leitungen 20 und 16 mit dem Bezugszeichen 25 versehen ist, liegt und somit ständig ein Flüssigkeitsdruck anliegt und eine Benetzung mit Flüssigkeit stattfindet. Insbesondere eine Anordnung in einem beruhigten Pumpensumpf hat sich als vorteilhaft erwiesen. Die Meßzelle 4 ist in der druckbeaufschlagten Seite des Wasserzulaufes, stromauf von der programmgesteuerten Ventilvorrichtung 6 angeordnet, so daß auch an dieser Meßzelle ständig ein Flüssigkeitsdruck anliegt und eine Benetzung der Meßzelle mit Flüssigkeit ständig gewährleistet ist. Die Auswertung des Signals der Meßzelle 4 erfolgt nur bei abgesperrter Ventilvorrichtung 6.The conductivity measuring cells 4 and 24 have the same electrical cell constants and conductivity values. With the conductivity measuring cell 4 the specific electrical conductivity of the water entering the washing machine 1 is measured and with the conductivity measuring cell 24 the specific electrical conductivity of the water pumped out of the washing machine 1 is measured in each case in a temperature-compensated manner. The measuring cell 24 is arranged in the section 20a of the drain line 20, in which the residual water remains after the pumping has ended, so that it is permanently below the liquid level, which is provided in the lines 20 and 16 with the reference number 25, and thus is constantly on Liquid pressure is present and wetting takes place with liquid. In particular, an arrangement in a calmed down pump sump has proven to be advantageous. The measuring cell 4 is arranged in the pressurized side of the water inlet, upstream of the program-controlled valve device 6, so that a liquid pressure is constantly present at this measuring cell and wetting of the measuring cell with liquid is constantly ensured. The signal from the measuring cell 4 is only evaluated when the valve device 6 is shut off.

Die Leitfähigkeitsmessungen werden im Zustand ohne Flüssigkeitsströmung am Ende einzelner Programmschritte durchgeführt und dieser Meßwert wird bis zum nächsten Programmschritt gespeichert. Dieser Meßwert wird als "wahrer Leitwert" angenommen, wenn er nach mehreren Einzelmessungen eine Drift unter 2 µS/cm aufweist. Außerdem ist dann der Temperatursensor im eingeschwungenen Zustand.The conductivity measurements are carried out in the state without liquid flow at the end of individual program steps and this measured value is stored until the next program step. This measured value is assumed to be the "true conductance" if it shows a drift below 2 µS / cm after several individual measurements. In addition, the temperature sensor is then in the steady state.

Aus den mit den Meßzellen 4 und 24 ermittelten Meßwerten wird der Differenzleitfähigkeitsmeßwert unter Einbeziehung der speziellen Temperaturkompensationswerte für das Zulauf- und das Ablaufwasser errechnet und dieser Wert der Steuerelektronik der Waschmaschine als Signal für die Programmsteuerung zugeführt. Dies kann beispielsweise eine Wiederholung oder Beendigung des anstehenden oder gerade durchgeführten Spül- oder Schleudervorganges bewirken.From the measured values determined with the measuring cells 4 and 24, the differential conductivity measured value is calculated, taking into account the special temperature compensation values for the inlet and outlet water, and this value is fed to the control electronics of the washing machine as a signal for the program control. This can result, for example, in a repetition or termination of the pending or just carried out rinsing or spinning process.

Die von den Meßzellen 4 und 24 gelieferten Meßwerte bzw. der Differenzleitwert wird in der Steuerelektronik der Waschmaschine in Abhängigkeit vom eingestellten Waschprogramm bzw. zusätzlich vom aktuellen Progammschritt innerhalb des Waschverfahrens individuell ausgewertet und mit Kennwerten, die zur Auslösung bestimmter Schaltvorgänge in der Waschmaschinensteuerung abgespeichert sind, verglichen. In Abhängigkeit von der Differenz zwischen dem Differenzleitfähigkeitsmeßwert und dem einprogrammierten Sollwert kann die Programmablaufsteuerung dann dahingehend beeinflußt werden, die in die Waschmaschine einfließende Wassermenge oder beispielsweise auch die Schleuderdrehzahl der Waschmaschinentrommel zu verändern. Weiterhin kann vorgesehen sein, daß ein Fehlen des Differenzleitfähigkeitsmeßsignals von der Steuerungselektronik als Störung gewertet wird. Hiermit kann z.B. bewirkt werden, daß der Programmablauf unterbrochen wird, wenn Wassermangel oder Waschmittelmangel vorliegt.The measured values delivered by the measuring cells 4 and 24 or the differential conductance are individually evaluated in the control electronics of the washing machine depending on the washing program set or additionally on the current program step within the washing process and with characteristic values which are stored in the washing machine control system to trigger certain switching processes. compared. Depending on the difference between the differential conductivity measured value and the programmed target value, the program sequence control can then be influenced to change the amount of water flowing into the washing machine or, for example, also the spin speed of the washing machine drum. Furthermore, it can be provided that a lack of the differential conductivity measurement signal is evaluated by the control electronics as a disturbance. With this e.g. cause the program to be interrupted if there is a lack of water or a lack of detergent.

Die im Waschmaschinenraum 7 angeordneten Leitfähigkeits-Meßzellen 10 können so ausgelegt sein, daß die dort gemessene spezifische elektrische Leitfähigkeit und der jeweilige Temperaturkoeffizient mit den bei den einzelnen Waschzyklen üblicherweise vorliegenden und in der Steuerelektronik abgespeicherten Werten eines bestimmten Waschmittels verglichen werden können.The arranged in the washing machine room 7 conductivity measuring cells 10 can be designed so that the specific electrical conductivity measured there and the respective temperature coefficient with those in the Individual washing cycles of the values of a particular detergent that are usually present and stored in the control electronics can be compared.

Sowohl die Leitfähigkeits-Meßzelle 10 als auch die Leitfähigkeits-Meßzelle 24 können weiterhin zur Ansteuerung einer nicht näher dargestellten Dosiereinrichtung zur Erzielung einer wäscheart- und waschprogrammabhängigen Konzentration an waschaktiver Substanz im Waschmaschinenraum verwendet werden. Insbesondere können hierbei die Meßzellen im Waschmaschinenraum 7 auch zur Strömungsauswertung, beispielsweise der Anzeige von Wassermangel, und zur Bestimmung von Über- bzw . Unterkonzentrationen an Waschmittel in der Waschlauge herangezogen werden. Ebenso läßt sich die Bewegung der Waschtrommel dadurch kontrollieren, daß die Leitfähigkeitsmeßzelle rhythmisch überflutet und freigelegt wird.Both the conductivity measuring cell 10 and the conductivity measuring cell 24 can also be used to control a metering device (not shown in more detail) in order to achieve a concentration of detergent substance in the washing machine room that is dependent on the type of washing and the washing program. In particular, the measuring cells in the washing machine room 7 can also be used for flow evaluation, for example the display of lack of water, and for determining excess or. Lower concentrations of detergent in the wash liquor can be used. The movement of the washing drum can also be controlled by rhythmically flooding and exposing the conductivity measuring cell.

Speziell läßt sich auch die Schaumentwicklung im Waschmaschinenraum 7 über die Signalauswertung der dort eingebauten elektrischen Leitfähigkeits-Meßzellen 10 messen und für einen direkten Eingriff in die Programmablaufsteuerung zur Reduzierung bzw. Beseitigung der Schaumentwicklung nutzen, indem diese beispielsweise einen vorübergehenden Maschinenstop, eine Senkung der Waschlaugentemperatur, eine Veränderung der Trommeldrehzahl, eine Veränderung der Intervallzeiten, die Zugabe von Frischwaser, etc. bewirkt.Specifically, the foam development in the washing machine room 7 can also be measured via the signal evaluation of the electrical conductivity measuring cells 10 installed there and used for a direct intervention in the program sequence control to reduce or eliminate the foam development, for example by a temporary machine stop, a lowering of the washing liquor temperature, a change in the drum speed, a change in the interval times, the addition of fresh water, etc. causes.

Die elektrische Leitfähigkeits-Meßzelle 4 im Wasserzulauf ist vorgesehen, damit auch Schwankungen im Leitfähigkeitswert des Zulaufwassers, der auch innerhalb der gleichen Wasserversorgung durch jahreszeitliche oder technisch bedingte Umstände stark schwanken kann, jeweils zutreffend erfaßt wird. Die Meßzelle 4 ist mit einem schnellwirkenden Temperatursensor versehen. Weiterhin muß damit ein Temperaturkoeffizient einstellbar sein, damit bei den hier typisch anzutreffenden niedrigen Leitfähigkeitswerten im Mikrosiemensbereich, z.B. 200 bis 1200 µS, der Meßfehler nicht zu groß wird. Die Meßzelle 4 ist im druckbeaufschlagten Vorlauf vor den Wassereinlaufmagnetventilen 6 angeordnet und unterliegt dadurch langzeitstabilen Meßbedingungen.The electrical conductivity measuring cell 4 in the water inlet is provided so that there are also fluctuations in the conductivity value of the inlet water, which also occurs within the same water supply due to seasonal changes or may fluctuate greatly due to technical reasons, is correctly recorded in each case. The measuring cell 4 is provided with a fast-acting temperature sensor. Furthermore, it must be possible to set a temperature coefficient so that the measurement error does not become too great given the low conductivity values typically found in the microsiemens range, for example 200 to 1200 μS. The measuring cell 4 is arranged in the pressurized flow in front of the water inlet solenoid valves 6 and is therefore subject to long-term stable measuring conditions.

An der im Wasserablauf vorgesehenen Leitfähigkeits-Meßzelle 24 steht immer das zuletzt aus dem Waschmaschinenraum 7 abgepumpt Abwasser an, und zwar so lange, bis der nächste Abpumpvorgang beginnt und das alte anstehende Abwasser durch den Siphon 21 hindurch die Waschmaschine verläßt. Die Meßzelle 24 ist ebenfalls temperaturkompensiert, um die bei verschiedenen Wäschearten und Waschprogramme verschiedenen Waschlaugentemperaturen in Bezug auf ihren Einfluß auf den Differenzleitfähigkeitsmeßwert kompensieren zu können. Vorzugsweise wird der Temperaturkoeffizient auf die typischen Werte einer stark verdünnten alkalischen, wäßrigen Flüssigkeit eingestellt, welcher dem Wasserwert ähnlich ist. Aufgrund ihrer Anordnung im Bereich des Siphons 21 ist die Meßzelle 24 ebenfalls langzeitstabilen Meßbedingungen, insbesondere einer ständigen Benetzung der Meßzelle, unterworfen.At the conductivity measuring cell 24 provided in the water drain, the wastewater last pumped out of the washing machine room 7 is always present until the next pumping process begins and the old pending wastewater leaves the washing machine through the siphon 21. The measuring cell 24 is also temperature-compensated in order to be able to compensate for the different washing liquor temperatures in different types of laundry and washing programs with regard to their influence on the differential conductivity measured value. The temperature coefficient is preferably set to the typical values of a highly dilute alkaline, aqueous liquid which is similar to the water value. Because of its arrangement in the area of the siphon 21, the measuring cell 24 is also subjected to long-term stable measuring conditions, in particular constant wetting of the measuring cell.

Diese Dauerbenetzung der Durchflußmeßzellen hat den Vorteil, daß die Trägheit des Temperaturfühlers eleminiert wird, weil in jedem Falle im Rahmen auch schnell ablaufender Waschprogramme die erforderliche Zeit zum erwärmungsmäßigen Einschwingen des Temperaturfühlers gegeben ist. Dieses Einschwingen des Temperaturfühlers ist Voraussetzung für eine richtige Temperaturkompensation und diese wiederum Voraussetzung für eine korrekte Messung und Differenzwertbildung. Ohne die Anordnung läßt sich ein sicherer Meßwert nicht ermitteln, wenn dieser im Bereich weniger Mikrosiemens genau sein soll.This permanent wetting of the flow measuring cells has the advantage that the inertia of the temperature sensor is eliminated, because in any case, in the context of rapidly running washing programs, the time required for the temperature sensor to settle warmly given is. This settling of the temperature sensor is a prerequisite for correct temperature compensation and this in turn is a prerequisite for correct measurement and formation of a difference value. Without the arrangement, a reliable measured value cannot be determined if it is to be accurate in the range of a few microsiemens.

Die beiden Meßzellen 4 und 24 sind als einfache Zwischenstücke in den Leitungen 2 und 20 angeordnet. Ihre Meßzellengeometrie entspricht den Erfordernissen einer niedrigen Zellkonstante, z.B. 1,0, und den hygienischen Anforderungen im Hinblick auf geringstmögliche Ablagerungen. Die Temperaturfühler besitzen eine Zeitkonstante im unteren Sekundenbereich, damit die Zeitdauer der Meßwertverfälschung aufgrund des Einschwingens auf den richtigen Temperaturwert möglichst gering gehalten ist. Diese Einlaufzeit wird meßtechnisch ausgeblendet.The two measuring cells 4 and 24 are arranged as simple intermediate pieces in the lines 2 and 20. Their measuring cell geometry corresponds to the requirements of a low cell constant, e.g. 1.0, and the hygienic requirements with regard to the lowest possible deposits. The temperature sensors have a time constant in the lower second range, so that the duration of the measurement value falsification is kept as short as possible due to the settling to the correct temperature value. This run-in time is hidden from the measurement.

Die mittels der Meßzellen 4 und 24 ermittelten Leitfähigkeitsmeßwerte werden in einer Differenzrechenschaltung entweder analog oder digital verarbeitet und mit Schaltpunkten der Programmablaufsteuerung verknüpft. Zweckmäßigerweise sollte ein Mikroprozessor mit permanentem Speicher für die Meßwerte vorgesehen sein, damit bei Stromausfall der letzte Betriebszustand festgehalten werden kann.The conductivity measured values determined by means of the measuring cells 4 and 24 are processed either analog or digital in a differential arithmetic circuit and linked to switching points of the program sequence control. A microprocessor with permanent memory for the measured values should expediently be provided so that the last operating state can be recorded in the event of a power failure.

Dem Kurvenverlauf des ermittelten Differenzleitfähigkeitsmeßwertes werden mittels der Steuerelektronik verschiedene Schaltpunkte der Programmablaufsteuerung zugeordnet, die in Abhängigkeit von der programmierten Wäscheart ausgewählt und aktiviert werden und den Ablauf des Waschprogrammes innerhalb des gerade anstehenden Programmschrittes bzw. Waschzyklus steuern.The control electronics are used to assign various switching points of the program sequence control to the curve profile of the differential conductivity measured value which are selected and activated as a function of the programmed type of laundry and which control the course of the washing program within the program step or washing cycle which is currently pending.

Ebenfalls in Abhängigkeit von der Wäsche- und Faserart ist der Wasserzufluß aufgrund der ermittelten Meßwerte zu steuern, ebenso die Zeit und Anzahl der Laugenverdünnungs- und Mischvorgänge und insbesondere die Dauer und Umdrehungszahl des Zwischenschleuderns. Das zuletzt abgepumpte Schleuderwasser ist für die Endqualität des zustandsabhängigen Spülens maßgeblich. Sollte der Endwert trotz vorangegangener Spüloptimierung noch von der Norm abweichen, so kann ein weiterer Spül- und Schleudervorgang ausgelöst werden.Also depending on the type of laundry and fiber, the water inflow is to be controlled on the basis of the measured values determined, as are the time and number of alkali dilution and mixing processes, and in particular the duration and number of revolutions of the intermediate spin. The centrifuged water pumped out last is decisive for the final quality of the condition-dependent rinsing. If the final value still deviates from the norm despite previous rinsing optimization, a further rinsing and spinning process can be triggered.

Die von den Meßzellen 4 und 24 ausgehenden Signale können auch für Störungsmeldungen benutzt werden. Beispielsweise kann mittels der Zelle 4 ein leerer Wasserzulaufschlauch oder stark verschmutztes Wasser gemeldet werden, wenn entweder kein Meßwertsignal oder ein Signal, das oberhalb eines Grenzwertes liegt, gemessen wird. Die Meßzelle 24 kann weiterhin dazu benutzt werden, festzustellen, ob in der Waschlauge eine Unterkonzentration vorliegt. Auch ein fehlerhafter Betrieb der Laugenpumpe kann mit dieser Meßzelle festgestellt werden, da der Übergang von einem Waschzyklus zu einem nächsten Waschzyklus üblicherweise auch mit einer Änderung der elektrischen Leitfähigkeit in der Waschlauge bzw. dem Waschwasser verbunden ist. Ist bei einem derartigen Waschzykluswechsel eine Änderung der elektrischen Leitfähigkeit nicht feststellbar, so kann man daraus auf eine defekte Laugenpumpe oder ein verstopftes Flusensieb schließen.The signals from the measuring cells 4 and 24 can also be used for fault reports. For example, an empty water supply hose or heavily contaminated water can be reported by means of cell 4 if either no measured value signal or a signal that is above a limit value is measured. The measuring cell 24 can also be used to determine whether the wash liquor is under-concentrated. Faulty operation of the drain pump can also be determined with this measuring cell, since the transition from one wash cycle to a next wash cycle is usually also associated with a change in the electrical conductivity in the wash liquor or the wash water. If a change in the electrical conductivity cannot be determined during such a washing cycle change, it can be concluded from this that a defective drain pump or a blocked lint filter.

Die Leitfähigkeits-Meßzellen 10 im Waschmaschinenraum 7 dienen der Bestimmung der Konzentration an Waschmittel in der Waschlauge und der Kontrolle der Schaumentwicklung. Da man insbesondere im gewerblichen und kleingewerblichen Bereich, aber auch bei Haushaltswaschmaschinen, davon ausgehen kann, daß üblicherweise gleiche Waschmittel verwendet werden, die annähernd gleiche Leitfähigkeitswerte in der Waschlauge erzeugen, ist mit diesen Meßzellen eine Über- oder Unterdosierung, welche eine vom Normwert abweichende Leitfähigkeit in der Waschlauge bewirken, festzustellen. Diese Abweichung kann in der Steuerelektronik dazu verarbeitet werden, entweder weiteres Waschmittel zuzudosieren oder Frischwasser zuzuführen.The conductivity measuring cells 10 in the washing machine room 7 serve to determine the concentration of detergent in the wash liquor and to control the development of foam. Since one is particularly in the commercial and small trade Area, but also for household washing machines, it can be assumed that the same detergents are usually used, which produce approximately the same conductivity values in the wash liquor, with these measuring cells an overdosing or underdosing, which cause a conductivity in the washing liquor deviating from the standard value, can be determined. This deviation can be processed in the control electronics to either add more detergent or to supply fresh water.

Ist eine der Meßzellen 10 im Bereich des Normalniveaus 11 im Waschmaschinenraum 7 angeordnet, so läßt sich diese als elektrischer Schaumdetektor bzw. -sensor nutzen. Die Schaumbildung hat zur Folge, daß das Füllstandsniveau unter das von der Meßzelle 10 erfaßte Niveau absinkt und sich die Flüssigkeit teilweise in den Schaumbläschen verteilt. Hierdurch läßt sich von der Leitfähigkeits-Meßzelle ein Leitfähigkeitsmeßwert nur dann feststellen, wenn gerade Schaumbläschen an der Zelle anliegen. In diesem Zustand bewirken die Schaumbläschen zwischen den Elektroden einer jeden Meßzelle einen kurzen Stromfluß, wenn Schaum zwischen den Elektroden anliegt, welcher sofort wieder unterbrochen wird, wenn der Schaum aus der Meßzelle herausläuft. Somit treten nur sporadisch und innerhalb einer sehr kurzen Zeit schwankende elektrische Signale auf. Die Änderungsgeschwindigkeit und die Änderungshöhe, bezogen auf den absoluten Signalpegel der bei Normalniveau anliegenden Lauge, sind im Sinne einer Signalkurvenauswertung, beispielsweise einer Fouriertransformation, für den Schaum und bestimmte Zustandsformen des Schaums charakteristisch. Dies läßt sich zur Erfassung des Schaumzustandes im Waschmaschinenraum 7 nutzen. Diese elektrische Methode der Schaumerkennung ist bezüglich ihres Ansprechverhaltens schneller als die bisher üblichen Differenzdruckmeßverfahren und sie reagiert auch wesentlich frühzeitiger als beispielsweise eine Druckmeßdose. Ist mittels der Leitfähigkeits-Meßzellen 10 die Entwicklung von Schaum festgestellt worden, können die elektrischen Signale in der Steuerelektronik zur Beeinflussung der Programmablaufsteuerung verwertet und z.B. in ein Anhalten der Rotationsbewegung der Waschtrommel 8 oder eine Erniedrigung der Waschtemperatur umgesetzt werden.If one of the measuring cells 10 is arranged in the area of the normal level 11 in the washing machine room 7, this can be used as an electrical foam detector or sensor. The result of the foam formation is that the fill level drops below the level detected by the measuring cell 10 and the liquid is partially distributed in the foam bubbles. As a result, a conductivity measurement value can only be determined from the conductivity measuring cell when foam bubbles are present on the cell. In this state, the foam bubbles between the electrodes of each measuring cell cause a short current flow when there is foam between the electrodes, which is immediately interrupted when the foam runs out of the measuring cell. Electrical signals therefore fluctuate only sporadically and within a very short time. The rate of change and the amount of change, based on the absolute signal level of the alkali present at normal level, are characteristic of the foam and certain states of the foam in the sense of a signal curve evaluation, for example a Fourier transformation. This can be used to detect the state of foam in the washing machine room 7. These The electrical method of foam detection is quicker in terms of its response behavior than the differential pressure measurement methods that have been customary up to now, and it also reacts much earlier than, for example, a pressure sensor. If the development of foam has been determined by means of the conductivity measuring cells 10, the electrical signals in the control electronics can be used to influence the program sequence control and can be implemented, for example, in stopping the rotational movement of the washing drum 8 or in lowering the washing temperature.

Durch die Übereinanderanordnung mehrerer Leitfähigkeits-Meßzellen 10 im Waschmaschinenraum 7, beispielsweise in der Rückwand des Waschmaschinenraums 7, kann die Schaumentwicklung für unterschiedliche Laugen bzw. Füllstandsniveaus detektiert bzw. festgestellt werden. Außerdem ist dadurch die Ansprechschwelle der Schaumerkennung variabel, so daß berücksichtigt werden kann, daß unterschiedliche Waschmittel und Waschprogramme sowie unterschiedlich verschmutzte Wäsche unterschiedliche Schaumentwicklung zufolge haben.By arranging a plurality of conductivity measuring cells 10 one above the other in the washing machine room 7, for example in the rear wall of the washing machine room 7, the foam development for different alkalis or fill level levels can be detected or ascertained. In addition, the response threshold of the foam detection is variable, so that it can be taken into account that different detergents and washing programs as well as differently soiled laundry have different foaming effects.

Durch diese als Schaumdetektor ausgebildeten Meßzellen 10 kann das Austreten von Schaum aus der Waschmitteleinspülkammer und somit Wasserschäden in und außerhalb des Gerätes vermieden werden. Auch kann hierdurch das Waschergebnis verbessert werden, da übermäßige Schaumentwicklung zu einer deutlichen Abnahme der Wirkung der Waschmechanik und damit zu einem schlechteren Waschergebnis führt.These measuring cells 10, which are designed as foam detectors, prevent foam from escaping from the detergent dispensing chamber and thus prevent water damage in and outside the device. This can also improve the washing result, since excessive foaming leads to a significant decrease in the effectiveness of the washing mechanism and thus to a poorer washing result.

In Fig. 2 sind die zeitlichen Abläuft der verschiedenen Prozesse des Waschmaschinenprogramms dargestellt. In der Kurve a) sind die aufeinanderfolgenden Abläufe Vorwäsche VW, Hauptwäsche HW und Spülvorgänge SP1,SP2 und SP3 dargestellt, wobei längs der Ordinate die Drehzahl n der Trommel 8 angegeben ist.2 shows the chronological sequences of the various processes in the washing machine program. In Curve a) shows the successive prewash VW, main wash HW and rinse processes SP1, SP2 and SP3, the speed n of the drum 8 being indicated along the ordinate.

In dem Diagramm b) sind in zeitlicher Zuordnung zu dem Diagramm a) die Wassermengen Q angegeben, die bei den verschiedenen Wasch- und Spülvorgängen jeweils im Waschmaschinenraum 7 enthalten sind. Die schrägen Flanken geben die Zeiten des Wasserzulaufs bzw. des Wasserabpumpens an.Diagram b) shows the quantities of water Q that are contained in the washing machine room 7 in the various washing and rinsing processes in chronological assignment to diagram a). The sloping flanks indicate the times of water intake or water drainage.

In dem Diagramm c) sind diejenigen Sperrzeiten 30 angegeben, in denen die Auswertung des Signals der Meßzelle 24 unterdrückt wird. Dies sind die Zeiten, in denen die Pumpe 15 Wasser aus dem Maschinenraum 7 abpumpt.Diagram c) shows the blocking times 30 in which the evaluation of the signal from the measuring cell 24 is suppressed. These are the times when the pump 15 pumps water out of the machine room 7.

In dem Diagramm d) ist die Leitwertdifferenz Δk angegeben, also die Differenz zwischen dem an der Meßzelle 24 gemessenen Leitwert und dem Referenzleitwert. Der Referenzleitwert ist der von der Meßzelle 4 gemessene und abgespeicherte Leitwert des Frischwassers. Das vorgegebene Maß Δkg des Differenzleitwertes, bei dem kein weiterer Spülvorgang erforderlich ist, beträgt bei dem vorliegenden Ausführungsbeispiel 50 µS/cm. Die Leitfähigkeitswerte sind jeweils spezifische Leitfähigkeiten.Diagram d) shows the conductance difference Δk, that is to say the difference between the conductance measured at measuring cell 24 and the reference conductance. The reference conductance is the conductance of the fresh water measured and stored by the measuring cell 4. The predetermined dimension Δk g of the differential conductance, at which no further rinsing process is required, is 50 μS / cm in the present exemplary embodiment. The conductivity values are specific conductivities.

Die Leitfähigkeit des vom Hauptwaschvorgang HW ablaufenden Wassers ist wegen des hohen Waschmittelgehalts sehr hoch und beträgt beispielsweise 8000 µS/cm. Dieser Wert ist in Fig. 2d) nicht eingetragen.The conductivity of the water running off the main washing process HW is very high because of the high detergent content and is, for example, 8000 µS / cm. This value is not entered in Fig. 2d).

Nach Beendigung des ersten Spülvorganges SP1 entsteht an der Meßzelle 24 während des Abpumpens des Spülwassers ein regelloses stark schwankendes Signal 31, wobei die Leitfähigkeit zu Beginn des Abpumpens stark absinkt und sich anschließend, wenn das aus den Tiefen des Gewebes kommende Restwasser zur Meßzelle gelangt, erhöht. Das vibrierende Signal 31 fällt in den Bereich einer Sperrzeit 30 und wird nicht ausgewertet. Nach Beendigung des Abpumpens steht das Restwasser in dem Abschnitt 20a und nach Ablauf einer Beruhigungszeit a von etwa einer Sekunde nach Beendigung des Abpumpens erfolgt im Punkt 32 die Leitfähigkeitsmessung bzw. die Auswertung des von der Meßzelle 24 gelieferten Leitfähigkeitssignals. Wenn der im Punkt 32 festgestellte Differenzleitwert noch über dem Maß Δkg liegt, wird anschließend der weitere Spülvorgang SP2 durchgeführt.After the first rinsing process SP1 has ended, an irregular, strongly fluctuating signal 31 is produced on the measuring cell 24 while the rinsing water is being pumped out, the conductivity dropping sharply at the beginning of the pumping and then increasing when the residual water coming from the depths of the tissue reaches the measuring cell . The vibrating signal 31 falls within the range of a blocking time 30 and is not evaluated. After the pumping has ended, the residual water is in the section 20a and after a settling time a of about one second after the pumping has ended, the conductivity is measured in point 32 or the conductivity signal supplied by the measuring cell 24 is evaluated. If the differential conductance determined in point 32 is still above the dimension Δk g , the further rinsing process SP2 is then carried out.

Aus Fig. 2d) ist erkennbar, daß nach dem zweiten Spülvorgang SP2 in der Phase des Abpumpens das Signal 31a kurzzeitig den Grenzwert Δkg unterschreitet. Da aber anschließend der stationäre Leitwert wieder über dem Grenzwert liegt, wird bei Auswertung im Punkt 32a entschieden, daß noch ein dritter Spülvorgang SP3 durchgeführt wird. Die Menge des bei diesem Spülvorgang verwendeten Wassers bemißt sich nach dem Abstand, den die gemessene Leitwertdifferenz von dem Grenzwert Δkg hat.From Fig. 2d) it can be seen that after the second rinsing process SP2 in the pumping phase, the signal 31a briefly falls below the limit value Δk g . However, since the steady-state conductance is again above the limit value, a decision is made in point 32a that a third rinsing process SP3 is still carried out. The amount of water used in this rinsing process is based on the distance between the measured conductance difference and the limit value Δk g .

Claims (8)

  1. A method for controlling the rinsing of a program-controlled washing machine which performs a plurality of rinsing operations following a washing operation, the electric conductivity of the rinsing water being measured and the rinsing being stopped if the difference between the measured conductivity value and a reference conductivity value falls below a predetermined amount,
       characterised in
       that the measuring of the conductivity value is performed in such a section (20a) of the drain conduit (20) in which, after the emptying of the space (7) of the washing machine, liquid is still present, that the measuring of the conductivity value is performed after the termination of a rinsing operation at the rinsing water present in said section (20a), and that the decision whether to perform another rinsing operation is made in dependence on the result of the measuring of the conductivity value.
  2. The method of claim 1, characterised in that reference conductivity value is the conductivity of the fresh water supplied, measured when the fresh water stands in the supply conduit (2).
  3. The method of claim 1 or 2, characterised in that the measured conductivity value is used as a control input for deciding upon the quantity of fresh water to be supplied during the next rinsing operation and/or upon a subsequent spin-drying operation.
  4. The method of one of claims 1 to 3, characterised in that, in addition, the electric conductivity is measured at at least one level in said washing machine space (7) and is evaluated for the control of the program flow.
  5. The method of one of claims 1 to 4, characterised in that the measurement of the conductivity is performed in said section (20a) between the evacuation pump (15) and a siphon (21).
  6. The method of one of claims 1 to 4, characterised in that the measurement of the conductivity is performed in a calm pump sump.
  7. A device for performing the method of one of claims 1 to 6, characterised in that a conductivity measuring cell (24) is provided in a section (a) of the drain conduit (20) of the washing machine, in which, after the evacuation of the washing machine space (7), liquid is still present, that the evaluation of the signal from said measuring cell (24) is effected after the termination of a rinsing operation, and that a control circuitry decides upon the performance of a further rinsing operation in dependence on the result of the measurement of the conductivity value by comparing the same to a reference value.
  8. The device of claim 7, characterised in that said reference value is provided by a further measuring cell (4) disposed in the water supply upstream of a valve device (6) controlled according to the machine program, the evaluation of the signal of said further measuring cell (4) being effected only when said valve device (6) is shut.
EP90102655A 1989-02-13 1990-02-10 Method to control the rinsing of a programme-controlled washing machine Expired - Lifetime EP0383218B1 (en)

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AT90102655T ATE87674T1 (en) 1989-02-13 1990-02-10 METHOD OF CONTROLLING THE FLUSHING OF A PROGRAM CONTROLLED WASHING MACHINE.

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DE3904222 1989-02-13
DE3904222A DE3904222A1 (en) 1989-02-13 1989-02-13 METHOD AND DEVICE FOR PROGRAM CONTROL OF WASHING MACHINES

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DE19650915B4 (en) * 1996-06-25 2006-09-21 AEG Hausgeräte GmbH Liquid-carrying household appliance with a program control
CN102356190A (en) * 2009-03-16 2012-02-15 Bsh博世和西门子家用电器有限公司 Method for optimizing a rinsing phase in a washing machine and washing machine suitable therefor
CN102413752A (en) * 2009-04-24 2012-04-11 伊莱克斯家用产品股份有限公司 Method for operating dishwasher
CN101608388B (en) * 2008-05-20 2013-06-12 三星电子株式会社 Control method of washing machine
DE102015204540A1 (en) 2015-03-13 2016-09-15 BSH Hausgeräte GmbH Method for operating a washing machine with an electrochemical sensor and suitable washing machine for this purpose
DE102015204538A1 (en) 2015-03-13 2016-09-15 BSH Hausgeräte GmbH Washing machine with electrochemical water hardness determination and method for its operation
US9708748B2 (en) 2014-05-30 2017-07-18 Lg Electronics Inc. Laundry treatment apparatus

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DE102007042968B4 (en) * 2007-09-10 2021-05-12 BSH Hausgeräte GmbH Method for detecting foam in a drum washing machine and a suitable drum washing machine
KR101692719B1 (en) 2008-04-30 2017-01-04 엘지전자 주식회사 Control methed of washing machine
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JP2024016745A (en) * 2022-07-26 2024-02-07 青島海爾洗衣机有限公司 drum type washing machine

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DE19650915B4 (en) * 1996-06-25 2006-09-21 AEG Hausgeräte GmbH Liquid-carrying household appliance with a program control
CN101608388B (en) * 2008-05-20 2013-06-12 三星电子株式会社 Control method of washing machine
CN102356190A (en) * 2009-03-16 2012-02-15 Bsh博世和西门子家用电器有限公司 Method for optimizing a rinsing phase in a washing machine and washing machine suitable therefor
CN102356190B (en) * 2009-03-16 2014-01-01 Bsh博世和西门子家用电器有限公司 Method for optimizing a rinsing phase in a washing machine and washing machine suitable therefor
US9481957B2 (en) 2009-03-16 2016-11-01 BSH Hausgeräte GmbH Method for optimizing a rinsing phase in a washing machine and washing machine suitable therefor
CN102413752A (en) * 2009-04-24 2012-04-11 伊莱克斯家用产品股份有限公司 Method for operating dishwasher
US9708748B2 (en) 2014-05-30 2017-07-18 Lg Electronics Inc. Laundry treatment apparatus
DE102015204540A1 (en) 2015-03-13 2016-09-15 BSH Hausgeräte GmbH Method for operating a washing machine with an electrochemical sensor and suitable washing machine for this purpose
DE102015204538A1 (en) 2015-03-13 2016-09-15 BSH Hausgeräte GmbH Washing machine with electrochemical water hardness determination and method for its operation

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ATE87674T1 (en) 1993-04-15
EP0383218A1 (en) 1990-08-22
DE3904222A1 (en) 1990-08-16
DE59001090D1 (en) 1993-05-06

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