CN107407034B - Method for operating washing machine with electrochemical sensor and washing machine - Google Patents

Abstract

The invention relates to a method for operating a washing machine (1) having a container (2), a drum (3) for receiving laundry (4), a drive motor (5) for the drum (3), an electrochemical sensor (9) in the container (2) for measuring an electrochemical signal related to a composition of an aqueous liquid (7) in the container (2), a control device (8), (a) providing the aqueous liquid (7) containing detergent in the container (2); (b) rotating the drum (3) according to a preset motion program; (c) ending the rotary motion of the drum (3) and smoothing the detergent-containing aqueous liquid (7) until a preset smooth state of the detergent-containing aqueous liquid (7) is achieved; (d) measuring the detergent concentration c of the aqueous liquid (7) of step (a) by receiving the electrochemical signal of the analytical electrochemical sensor (9) using the correlation between the electrochemical signal and the detergent concentration of the control device (8)_ten. The invention relates to a washing machine (1) suitable for carrying out said method.

Description

Method for operating washing machine with electrochemical sensor and washing machine

technical field

The present invention relates to a method for operating a washing machine with an electrochemical sensor and a washing machine suitable for this. In particular, the invention relates to a method for operating a washing machine having a container, a drum for receiving laundry, a drive motor for the drum, an aqueous liquid ( Flüssigkeit), an electrochemical sensor, and a control device for a composition-dependent electrochemical signal, and a washing machine suitable for carrying out such a method.

Background technique

In washing machines, the laundry is usually treated by means of a washing lye containing detergent in the washing stage for cleaning. Furthermore, after a rinsing phase with water in which washing lye and/or contaminants are removed from or on the washings, the washings are usually treated with softeners. Here, for cost reasons and environmental protection reasons, it makes sense to use an optimal amount of laundry treatment agents (especially detergents and softeners). Overdosing should be avoided but also underdosing should be avoided. In particular, an incorrect dosing of detergent can lead to bubbling over (overdosing) or to poor washing performance (underdosing). In order for this not to happen, it is desirable to monitor and optimally adjust the detergent concentration.

Therefore, a washing machine has been proposed which determines, for example, the optimal amount of detergent and can provide the user of the washing machine with a dosing recommendation with precise data, for example, the amount of detergent to be used, on a display screen. .

WO 03/029550 A1 describes a process-controlled domestic refrigerating appliance with a microcomputer and a display screen for text, in which the display screen is also provided for indicating predicted predictions during a working process (eg a washing program). Indication area for the amount of necessary additives (eg detergent). The household appliance has a device by which, for example, a washing method can be supplied with additives, the dosing of which must be carried out by an operator.

In order to save detergent, it makes sense to distribute the amount of detergent according to the type and intensity of soiling of the laundry to be washed. In addition to saving energy and water, a detergent dosing that is optimally adapted to a batch of laundry also results in, among other things, a lower load on the waste water.

DE 29 17 859 describes a method for monitoring and controlling programs, in particular water injection and/or detergent addition or rinsing agent addition programs, in automatic washing machines and dishwashers, wherein in the machine settings for washing Sensors responsive to the surface tension and/or water hardness and/or electrical conductivity of the liquid, which are embedded in the program flow via a control circuit and control the amount of water filling, water changes and/or the dosing of detergent or rinse agent additions .

EP 2 533 035 A1 describes a device for detecting material properties of a medium, the device having a measuring device comprising a sensor device, the sensor device being in connection with the medium, and the device having an The signal of the frequency range controls a control device of the sensor device, and the device has a control device for controlling the operation of the measuring device and for predetermining a predetermined frequency range, wherein the control device is provided for determining the impedance Z of the medium correspondingly According to the change curve of the frequency range predetermined according to the frequency and for outputting the detection signal, and the control device is configured to analyze and process the detection signal of the regulating device, and determine a plurality of characteristic curve of the impedance Z change. points (P1 to P4) and produce resultant signals about the properties of the medium. Thus, for example, it should be possible to determine whether the washing lye requires further addition of detergent.

EP 2 767 825 A1 describes a method and a device for determining the micelle formation concentration. The method is carried out in a washing device having the necessary amount of water in order to carry out the washing process, the method having the following steps:

- supplying a portion of the detergent to the water to form the washing lye (step 1),

并且产生相应的数量的相应的测量值(步骤2)，- Detect the magnitude Z and phase angle of the impedance of the washing lye for a predetermined number of frequencies of the regulation signal

and produce corresponding measurements of corresponding quantities (step 2),

- finding the slope from the individual measurements of the phase angle (step 3),

- the corresponding measurement is calculated from the number of slopes and the magnitude of the impedance (step 4),

- determining the product MBP from the mean value of the slope and the mean value of the magnitude of the impedance (step 5B),

- comparing the determined product with a predetermined threshold (step 6B), and

- Repeat steps 1 to 6B until it is determined that the product is equal to or greater than the threshold (XB) (step 7).

In order to monitor the concentration of detergents or other additives in the aqueous liquid in the lye container, optical or electrochemical sensors, such as turbidity sensors, impedance sensors, are usually used. It is to be taken into consideration here that, in order to form a washing lye for cleaning laundry, the detergent comprises in particular surfactants as surface-active substances, wherein the surfactants reduce the amount of water in the resulting aqueous solution (washing lye) The surface tension of the water in the water, since the surfactant is preferably adsorbed on the surface and at the same time on the contact surface. That is, in particular, the surfactant concentration in the aqueous liquid in the lye container is monitored.

The signal of the sensor can be distorted and, when the aqueous liquid to be measured is not sufficiently leveled and/or there is too much foam in the aqueous liquid, the signal of the sensor may be only poorly or generally unreadable. Analytical processing. In particular when the impedance sensor is used as an electrochemical sensor, this can result in no analyzable results.

EP 0 383 218 B1 describes a method for controlling the rinsing of a program-controlled washing machine, the method carrying out a plurality of rinsing programs following the washing process, wherein the conductivity of the rinsing water is measured, and when the measured The rinsing is ended when the difference between the conductance of the tester and the reference conductance falls below a predetermined value, wherein the conductance measurement is carried out in the section of the discharge pipe in which there is still a liquid, and, after finishing the flushing process, conduct a conductance measurement on the flushing water located in the section, and on the basis of the results of the conductance measurement it is decided whether to carry out a further flushing process. Here, the conductivity measurement is preferably carried out in a smooth pump sump.

SUMMARY OF THE INVENTION

Against this background, the object of the present invention is to provide a method for operating a washing machine which is improved in the measurement of electrochemical signals, in particular impedance signals of impedance sensors. Here, the preferred method is to monitor the washing program as simply and/or as accurately as possible. Furthermore, the task of the present invention is to provide a washing machine suitable for carrying out this method.

According to the invention, this task is solved by a method and a washing machine according to the invention. The preferred configuration of the method corresponds to the preferred configuration of the washing machine, even if this is not individually indicated here.

Accordingly, the present invention relates to a method for operating a washing machine having a container, a drum for receiving laundry, a drive motor for the drum, a measurement in the container for measuring and the water content in the container Electrochemical, and control apparatus for electrochemical signals related to the composition of a liquid, wherein the following steps are performed:

(a) providing an aqueous liquid containing detergent in a container;

(b) rotating the drum according to a predetermined motion program;

(c) ending the rotational movement of the drum and stabilizing the aqueous detergent-containing liquid (Ruhenlassen) until a predetermined steady state (beruhigter Zustand) of the aqueous detergent-containing liquid is reached; and

(d) measuring the provided in step (a) by receiving and analyzing the electrochemical signal of the electrochemical sensor using the correlation between the electrochemical signal and the detergent concentration stored in the control device The concentration c _ten of the detergent in the aqueous liquid containing the detergent.

Here, the term "aqueous liquid containing detergent" can be interpreted broadly. Here, detergent represents the detergent itself, including its constituents surfactants, enzymes, bleaching agents, etc., as well as softeners. Furthermore, the aqueous detergent-containing liquid may also be referred to as washing lye, eg free rinsing liquid or rinsing liquid, according to a stage in the washing program in which the aqueous detergent-containing liquid accumulates.

Furthermore, within the meaning of the present invention, a container is understood to mean a lye container, a part of a container or a component in which the aqueous liquid provided during operation of the washing machine is located in or next to the lye container/part/component of the container flow through. Therefore, the impedance sensor can be arranged in the lye container of the washing machine and in the measuring container or in the liquid line, which is connected in fluid communication with the lye container, via which the aqueous liquid passes during the operation of the washing machine. Liquid line flows. This can be particularly advantageous when the washing machine has a circulating pump system that conducts aqueous liquid from the lye container and resupplies the lye container during operation of the washing machine.

As a measure of the predetermined stationary state, for example, the contribution of convection to the transport process in the aqueous liquid can be considered.

In order to determine a sufficiently stationary state of an aqueous liquid, it is possible to consider the case in which various electrochemical measurement methods generate an electrochemical signal in the stationary state of an aqueous liquid, the Faradaic electrolytic part of which passes through the electroactivity in the aqueous liquid Diffusion of elektroaktiven Spezies was determined. If the aqueous liquid is not at rest, the transport of the electroactive species to the electrode is no longer caused by diffusion only, but also by convection. This typically results in a characteristic change in the electrochemical signal, which is a measure of the contribution of convection. Therefore, by analyzing the electrochemical signal, it is possible to infer the contribution of convection and therefore that the aqueous liquid may not be sufficiently stationary. Suitable electrochemical signals can be measured, for example, by means of voltammetric methods. In this case, such electrochemical signals can be obtained, for example, by using cyclic voltammetry, amperometry or double-pulse amperometry, but also by impedance spectroscopy.

In cyclic voltammetry, starting from the starting voltage, the voltage at the working electrode of the electrochemical sensor is changed at a generally constant rate up to the so-called reversal voltage U _λ (so-called "Hinsweep"), which The reversal voltage is sufficient for either the oxidation process or the reduction process. Then, the direction of the voltage change is reversed and the voltage is changed again towards the starting voltage (“Rücksweep”). The current occurring here generally increases to the peak value I _p during the forward sweep, so that it then drops to the value I _{λ until the reversal potential U λ .} Here, the proportional relationship I _p /I _λ is usually the characteristic parameter I _p /I _λ ^theor when the electrode operation process is controlled by diffusion. If the solution to be examined by voltammetry is in motion, this means the presence of convection, which generally leads to a decrease in _Ip / _Iλ . As a result, the value I _p /I _λ ^real or the difference ΔI = I _p /I _λ ^theor − I _p /I _λ ^real measured at that time can generally be taken as a measure of the contribution to the convection and thus of the stationary state of the aqueous liquid considered and used.

In amperometric methods, a voltage step is usually carried out to a suitable voltage, which is sufficient for the oxidation and reduction processes, and then the current reduction is measured and evaluated as a function of time. Here, the contribution of the convection generally leads to a decay of the current reduction. In the double-pulse amperometric method, a jump back to the starting voltage is then performed and the current reduction is measured and evaluated again as a function of time at the starting process voltage.

Therefore, in a preferred embodiment of the method according to the invention, the current-voltage curve is plotted in step (c) as a measure of the stationary state, and not the current fraction caused by diffusion to the electrochemical sensor For analysis processing.

Particularly advantageously, for this purpose, a cyclic voltammogram is plotted and, with regard to the current fraction not caused by diffusion to the electrochemical sensor, for the peak current when scanning forward to the reversal potential U _λ I _p and the current I _λ at the reversal potential U _λ are analyzed.

Alternatively or in addition to this, a potential step can be carried out using an electrochemical sensor and the current time curve obtained here can be evaluated with respect to the proportion not caused by diffusion, as a stationary state for the aqueous liquid (i.e. lack of stationarity). Here, a potential step is carried out, in particular to a potential at which the constituents in the aqueous liquid are reversibly or irreversibly oxidized or reduced.

If we speak of a potential change at an electrochemical sensor here, we mean in particular a potential change at the working electrode of the electrochemical sensor that constitutes the electrochemical sensor. Correspondingly, reference is made to diffusion and convection with reference to the transport of species to the working electrode.

In a particularly preferred embodiment of the method according to the invention, the aqueous liquid containing the detergent is stabilized in step (c) for a predetermined period of time Δt _set . Here, in order to determine Δt _set , preferably the amount of aqueous liquid, the load of laundry and/or the movement program performed in step (b) is taken into account, wherein the time period Δt _set already stored in the control device is taken into account , the amount of aqueous liquid, the amount of laundry and/or the interrelationship between the exercise program performed in step (b).

The quantity of aqueous liquid can be determined, for example, by measuring the quantity of water introduced into the container with the aid of a water quantity counter, wherein the portion of the introduced water that is absorbed by the laundry can be taken into account, and when, for example, a hydrostatic pressure is arranged in the container. When the pressure sensor for measuring the hydrostatic pressure is taken into account as a measure of the free rinsing liquid, the so-called free rinsing liquid (freie Flotte) can be determined.

The load of laundry can be adjusted by the user, or can however preferably be determined automatically in the washing machine. Here, the determination of the load can be carried out by measuring the weight gain of the drum due to the load of the laundry, or, however, can also be carried out by analyzing the suction properties of the water by adding water to the dry laundry During the previous period, changes in the hydrostatic pressure were analyzed. For this purpose, a hydrostatic sensor is advantageously provided in a washing machine according to the invention. Particularly advantageously, a water quantity counter, ie a measuring device for determining the quantity of water charged or the quantity of washing lye charged, is also provided. Thus, for example, the hydrostatic pressure p measured by means of a hydrostatic sensor can be compared with the quantity of water charged. The laundry in the drum absorbs water. Absorbed water may not contribute to the increase in hydrostatic pressure. By comparing the measured hydrostatic pressure p and the amount of water injected—absolute value and its change over time—with the corresponding value stored in the control unit of the washing machine for the soaking of the laundry, it is possible to find The load of the laundry and, if necessary, the degree of penetration (wetness) can be obtained.

In a further preferred embodiment, in order to stabilize the aqueous detergent-containing liquid until a predetermined plateau state of the aqueous detergent-containing liquid is reached, the effect of the electrochemical signal on the existing quantity of foam or concentration dependence. Here, the presence and amount of foam can be determined in different ways.

For example, the detection of suds in a washing machine can be carried out by means of conductometric measurements by means of two electrodes in the area below the container. In addition, foam detection can be achieved by means of the evaluation of the target/actual rotational speed difference during the spin-drying of the drum. Here, take advantage of the fact that the foam can brake the rotating drum, thereby causing a discrepancy between nominal and actual speed. Here, the correspondence between the determined foam concentration and the target/actual rotational speed difference is usually stored in the control unit of the washing machine. Typically, the presence of foam (liquid-air mixture) is detected by the pressure build-up during washing or centrifugation or by a strongly reduced pressure drop during pumping.

虚假的压力升高而导致测量误差。通过压力峰值的出现可以表明泡沫的存在，即便并不存在泡沫。这可归因于在借助传感器进行压力测量时的波动，其中，在信号接收、信号转换或者信号处理时的误差也与使用数字调节器还是使用模拟调节器相关。因为偶然的负值并不会被传感器检测到，因此求取不到真实的平均值(如果能够检测到负的部分，则可能得出所述真实的平均值)，而求取到振荡水量的提高的压力。此外，由压力传感器所测量的信号随着转速而升高，从而导致过早地超过为了识别泡沫而预先给定的压力阈值。因此，有利地，可以识别出洗衣机中的泡沫，其方式是，在滚筒以高的转速U_n旋转期间由用于确定位于容器中并且可能包含泡沫的液体的信号的传感器测量信号S_n并且将其与在程序控制装置中所存储的、对应于该转速U_n的值W_n比较，其中，在控制装置中，对于至少两个转速存储有值对U_n和W_n(n≥1)，并且，在达到或者超过值W_n时(即在满足条件S_n≥W_n时)，记录泡沫的存在。虽然在此传感器可以是光学的测量系统、测量电导率的测量系统或者电容的测量系统。优选是静液压的压力传感器，在所述该静液压的压力传感器中，作为信号，优选测量静液压的压力p和/或静液压的压力在时间上的负的梯度(dp/dt)、容器中的液体-空气混合物的优选静液压的压力p。信号S_n和对应的值W_n尤其是压力值。Usually, in order to detect the formation of foam, the hydrostatic pressure in the container is measured by means of sensors. For this purpose, pressure sensors, in particular hydrostatic pressure sensors, are generally used, which pressure sensors are also suitable, as explained above, for determining the water level in the container. Here, on the basis of the imbalance between the washings and the residual water that is present, which accumulates during the centrifugation, by feigning

False pressure rise resulting in measurement error. The presence of foam is indicated by the appearance of pressure peaks, even when no foam is present. This can be attributed to fluctuations in the pressure measurement by means of the sensor, wherein errors in signal reception, signal conversion or signal processing also depend on whether a digital controller or an analog controller is used. Because the occasional negative value is not detected by the sensor, the true average value cannot be obtained (if the negative part can be detected, the true average value may be obtained), and the value of the oscillating water volume is obtained. elevated pressure. Furthermore, the signal measured by the pressure sensor increases with the rotational speed, so that the predetermined pressure threshold value for the detection of foam is prematurely exceeded. Thus, it is advantageously possible to detect foam in the washing machine by measuring the signal _Sn by the sensor for determining the signal of the liquid located in the container and possibly containing foam during the rotation of the drum at a high rotational speed _Un and to use It is compared with the value W _n stored in the program control device corresponding to the rotational speed U _n , wherein in the control device the value pairs U _n and W _n (n≥1) are stored for at least two rotational speeds, And, when the value _Wn is reached or exceeded (ie when the condition Sn _{≧ Wn} is satisfied), the presence of foam is recorded. In this case, however, the sensor can be an optical measurement system, a conductivity measurement system or a capacitance measurement system. Preferably, a hydrostatic pressure sensor is used, in which the hydrostatic pressure p and/or the negative gradient of the hydrostatic pressure over time (dp/dt), the container, and/or the hydrostatic pressure are preferably measured as signals. The preferred hydrostatic pressure p of the liquid-air mixture in . The signal _{Sn and the corresponding value W n are} in particular pressure values.

Therefore, in a preferred embodiment of the method according to the invention, the presence of foam in the aqueous liquid is ascertained with a hydrostatic pressure sensor and taken into account for determining the stationary state of the aqueous liquid.

In addition, the presence of foam is also manifested in the electrochemical signal. That is, if the foam is in front of the electrodes, the measured current generally decreases. Therefore, the amount and duration of this sudden current reduction can be considered as a measure of the presence of foam, wherein the time interval Δt for smoothing (also called "reversing pause" or "roller standstill") can be appropriately extended stage”) until the foam concentration returns to an acceptable value.

The method used for the detection of foam generally depends on which stage of the washing programme (ie in particular the soaking stage, the washing stage, the rinsing stage or the softening stage) should be ensured that the aqueous solution is sufficiently stable to be able to receive effective electrochemical signal.

If a pressure sensor, in particular a hydrostatic pressure sensor, is present in the washing machine used, the measured pressure increase during the plateau phase (ie the drum standstill phase) due to the dripping aqueous liquid from the laundry can also be considered as A measure of the smoothness of aqueous liquids. That is, as time increases, the amount of dripped liquid decreases.

According to the invention, given a predetermined time period Δt _set , it can advantageously be provided that, by means of an electrochemical sensor, it is checked whether a sufficient leveling of the aqueous liquid has actually occurred. This can be done, as mentioned above, by determining the convection-induced proportion of the mass transport to the working electrode. If this is not the case, the predetermined time period Δt _set can be adjusted and in particular extended. Here, it can advantageously be provided that the maximum time period Δt _set ^max is not exceeded. When Δt _set ^max is reached or exceeded, the motion program of the drum is advantageously adjusted and in particular the introduction of mechanical energy is reduced. It can thus be achieved that a too long period of time is not required for the rotation of the drum to be intermittent.

The introduction of mechanical energy takes place by means of a suitable movement program of the drum. The movement program in step (b) of the method according to the invention comprises in particular the on time [in %], the duration of the commutation cycle [in seconds] and the rotational speed of the drum [rev/min]. The switch-on time is the time fraction of the phase of the washing program during which the drum rotates. The on-time is preferably 60% to 70%, for example in the first flushing step. A commutation cycle is typically a period of time that results from the following time periods: the drum is rotating in one direction, the drum is stationary, the drum is rotating in the opposite direction, and the drum is stationary.

For a sufficiently stationary determination and, in particular, confirmation of a predetermined time period Δt _set , the type of electrochemical measurement method used in step (d) is also advantageously taken into account, since electrochemical measurement methods may require the measurement of aqueous liquids. Different measurement times and stationary states.

The reception of the electrochemical signal is particularly accurate when relatively few contaminants and/or foam are present in the aqueous liquid to be examined. This is especially the case in the soaking phase and in the rinsing phase. Therefore, in a preferred embodiment of the method according to the invention, steps (c) and (d) are carried out in the soaking phase and/or in the rinsing phase.

In this context, the soaking phase is understood to mean the phase in the washing program in which the laundry to be cleaned and in particular to be washed with washing lye is wetted with the washing lye used for this, usually until the washing The material is saturated with washing lye. Here, the laundry usually moves only slightly or not at all. Consequently, generally only a small separation of contaminants from the laundry to be washed occurs during the soaking phase. In particular, the laundry drum preferably does not rotate at a number of revolutions greater than 25 revolutions per minute during the soaking phase. Here, "washing lye" and "surfactant-containing aqueous liquid" generally have the same meaning. The term "surfactant" as used herein refers to single surfactants as well as mixtures of different surfactants.

A certain degree of movement of the aqueous liquid by means of the movement program and therefore the subsequent standstill phase of the drum is necessary, which degree also depends on the presence and shape of the laundry entrainers in the drum. If the shape of the laundry carrier is asymmetric, its contribution to the movement of the aqueous liquid depends on the direction of rotation, given the rotational speed of the drum. Therefore, in the case of an asymmetrical shape of the laundry entrainer used in the drum, at least the direction of rotation of the drum before the drum standstill phase is taken into account.

According to the invention, step (c) and/or step (d) are preferably carried out taking into account the type of contamination and/or the amount of contamination of the laundry, wherein in the control device the different types of contamination and/or the amount of contamination of the laundry are The amount of contamination stores the correlation between the electrochemical signal and the detergent concentration.

In the case of oil contamination, for example, it can result that especially nonionic surfactants can dissolve in the oil to a greater or lesser extent and can no longer be detected when measuring the detergent concentration. On the other hand, ionic surfactants can be intercepted (ie, consumed) to a certain extent by ion-containing contaminants such that they are no longer detected when electrochemical signals are measured.

The type of soiling and/or the amount of soiling can be adjusted by the user of the washing machine, or can however be measured by suitable sensors. Electrochemical sensors provided according to the invention, for example impedance sensors, are particularly suitable for this. In addition, other sensors, such as, for example, turbidity sensors, can of course also be used in addition.

Electrochemical sensors are usually electrode systems consisting of at least two electrodes. When using a three-electrode arrangement consisting of a working electrode, a counter electrode and a reference electrode, the potential at the working electrode, which is responsible for receiving the electrochemical signal, can be adjusted particularly precisely.

In any case, according to the present invention, a single electrode system can be used for receiving different electrochemical signals, ie for example for cyclic voltammetry or impedance spectroscopy in which the electrical Chemical sensors are also known as impedance sensors. According to the invention, the electrochemical sensor is preferably used in step (d) as an impedance sensor. Here, the impedance sensor receives the impedance signal as an electrochemical signal.

和量值。In the method according to the invention, the reception and evaluation of the impedance signal is usually carried out in that the impedance sensor is loaded with an alternating voltage with a changing frequency and the phase angle of the impedance is measured Analyze and process impedance signals in terms of magnitude. The phase angle of the treatment impedance can then again be analyzed in terms of the type, amount and concentration of the detergent, especially the surfactant, and also the concentration of micelles

and magnitude.

For measurement, the impedance spectrum is usually received by using a suitable electrode system as an impedance sensor. Here, the impedance of the electrochemical system is checked as a function of the frequency of the alternating voltage on the working electrode. For illustration, the person skilled in the art knows different diagrams, such as for example a Nyquist diagram, in which the real or imaginary part of the impedance is shown depending on the frequency of the alternating voltage used. When examining washing lye, usually several characteristic points are suitable for characterizing the impedance spectrum (compare EP 2 767 825 A1), for example the point with the imaginary part at the maxima in the lower frequency range or the imaginary part in the upper part The point on the minimum value in the frequency range. For aqueous liquids containing detergents, typical parameters can generally be derived from impedance values and frequency values at characteristic points. For example, the conductivity of the liquid can be determined from the real part of the point. Generally speaking, by analyzing the impedance at this point and the frequency at another point, the capacitance of the so-called conductivity measuring cell formed by the impedance sensor and the washing lye can be determined. Another parameter related to the properties of the washing lye is the smoothness (Abflachung) of the semicircle in the Nyquist diagram, which can be determined by the ratio of the height to the width of the semicircle. Analytical processing is performed by using formulas known to those skilled in the art.

In a particularly preferred embodiment of the invention, the impedance signal is evaluated in terms of conductance as a measure of the water hardness of the aqueous liquid.

和量值而言阻抗信号进行分析处理。在这里，特别优选的是，在交变电压的频率预先给定的情况下执行阻抗信号的接收。Therefore, according to the invention, the impedance signal is preferably received with an impedance sensor, wherein the reception and evaluation of the impedance signal is performed in that the impedance sensor is loaded with an alternating voltage with a changing frequency and the phase angle of the impedance is measured

The impedance signal is analyzed and processed in terms of magnitude. Here, it is particularly preferred that the impedance signal is received with a predetermined frequency of the alternating voltage.

A washing stage is usually followed by a soaking stage. Usually, if the washing program signals that there is sufficient wetting of the laundry, for example by reaching a predetermined threshold value p ₁ for the hydrostatic pressure p and a predetermined pressure p for the hydrostatic pressure p At the threshold of the gradient in time (Δp/Δt) ₁ , the wash phase begins. Especially in the washing phase, it is of interest to monitor the detergent concentration with electrochemical sensors. From this, the consumption of detergent and thus a possible requirement for a wash-up dose can be determined. Furthermore, the washing program can be optimally coordinated with the determined detergent concentration.

Furthermore, the subject matter of the present invention is a washing machine having a container, a drum for receiving the laundry, a drive motor for the drum, an electric power in the container for measuring in relation to the composition of the aqueous liquid in the container An electrochemical sensor for chemical signals, and a control device, wherein the control device is configured to perform a method comprising the steps of:

(a) providing an aqueous liquid containing detergent in a container;

(b) rotating the drum according to a predetermined motion program;

(c) ending the rotational movement of the drum and smoothing the detergent-containing aqueous liquid until a predetermined steady state of the detergent-containing aqueous liquid is reached; and

(d) measuring the electrochemical signal provided in step (a) by receiving and analyzing the electrochemical signal of the electrochemical sensor using the correlation between the electrochemical signal and the detergent concentration stored in the control device The concentration c _ten of the detergent in the detergent-containing aqueous liquid.

According to the invention, a washing machine is preferred, in which a temperature sensor is arranged in the container, and in which an electrochemical signal (eg an impedance signal) and a washing machine are stored in the control device for different temperature values measured with the temperature sensor. The relationship between the concentration of the agent.

The washing machine according to the invention realizes that the turbidity sensor normally present in washing machines is omitted. Of course, in some embodiments of the washing machine according to the invention, a turbidity sensor may also be provided in addition.

Usually, the washing machines used here also have a heating device and a lye discharge system with a lye pump, which is arranged on the floor of the lye container. Furthermore, the washing machines used here often also have a laundry carrier and/or a pick-up device

Finally, the washing machine according to the present invention may be a washing machine itself or a washer-dryer (ie an appliance with the functions of a dryer and a washing machine).

Preferably, the washing machine according to the invention has acoustic and/or optical display means for displaying one or more operating states. The optical display device can be, for example, a liquid crystal display, on which certain requirements or indications are marked. Additionally or alternatively, the light emitting diodes can flash in one or more colors. For example, on the basis of the different colored diagrams, it can be indicated whether the washing phase is running at the optimum detergent concentration. Furthermore, it can also be shown whether the measurement was carried out in a sufficiently stable aqueous liquid by means of the electrochemical sensor.

In the event of an insufficient amount of detergent, the user of the washing machine can be prompted to add the amount of detergent, wherein the quantity can also be specified here. In this case, the dosage recommendations are displayed on the display screen itself or on its indication area (referred to here generally as “display screen”).

Dosing recommendations can be shown in text and/or symbols on the display. A suitable text might be, for example, the direct request "Dosing "green", where "green" is a prompt for a dosing aid. Other colors can also be listed or other hints given in text form. Alternatively or in addition to this, colors or symbols can be displayed as symbols, for example circles, which can be filled to different degrees in order to distinguish individual detergent quantities.

In the embodiment of the present invention, it is important to know the amount of water or water lye that flows into the container. Therefore, in the washing machine according to the invention, a measuring device is preferably provided for determining the amount of water charged, for example a timing device for determining the opening period of the filling valve for the water or for measuring the amount of water charged liquid volume measuring equipment.

The present invention has numerous advantages. A method for operating a washing machine is provided, in which the monitoring of the concentration of detergent, for example in washing lye, is carried out particularly accurately by means of electrochemical sensors, in particular impedance sensors. According to the invention, this is achieved by taking into account that, if the solution is not sufficiently stable at the measurement time, it may interfere with the electrochemical measurement and in particular the measurement of the impedance signal by means of the impedance sensor and thus the measured Impedance signal distortion. The invention makes it possible, in particular, by means of electrochemical sensors in aqueous liquids containing detergents, in particular surfactants, by means of impedance measurements and circulation by adapting the intermittency of the reversing of the drum during wetting, washing and rinsing. Voltammetry accurately determines surfactant concentration and water hardness and avoids erroneous measurements due to air bubbles, foam, and flow contained in aqueous liquids.

所述冒泡溢出可能与住宅中的水损相关。另一方面，可以避免对冲洗水的过量使用，如果必须要从洗涤物中清除过剩的洗涤剂，所述冲洗水可能是必需的。也例如使得能够更准确地确定出离子的表面活性剂的浓度以及能够将针对离子的表面活性剂的浓度范围更准确地调节和维持。By determining the actual detergent concentration and the measures related thereto more accurately in the washing program, it is possible to influence the overdosing or underdosing of the detergent in a timely manner. On the one hand, it can prevent the occurrence of washing machine bubbling and overflow

The bubbling spill may be associated with water damage in the dwelling. On the other hand, excessive use of rinse water, which may be necessary if excess detergent must be removed from the wash, can be avoided. It also enables, for example, to more accurately determine the ionic surfactant concentration and to more accurately adjust and maintain the ionic surfactant concentration range.

Description of drawings

The invention is explained below with reference to a non-limiting embodiment of the washing machine according to the invention shown in the single drawing. A schematic representation showing parts of a first embodiment of a washing machine according to the invention which are essential to the invention, in which the method according to the invention can be carried out.

Detailed ways

The washing machine 1 of the drawing has a lye container 2 in which a drum 3 is rotatably mounted and can be driven by a drive motor 5 . For improved ergonomics, the rotation axis 19 of the drum 3 is oriented at a small angle (eg 13°) from the horizontal towards the front and upward, so that the user of the washing machine 1 can more easily reach and observe the interior of the drum 3 . Furthermore, by this arrangement, also in cooperation with the laundry carrier 14 on the inner surface of the drum shell and the suction device 17 for the aqueous liquid containing detergent, for example the washing lye 7, the use of washing lye is also achieved 7 Intensification of the Durchflutung laundry 4. In the embodiment shown here, the laundry carrier 14 is asymmetrical, so that for the two possible directions of rotation of the drum 3, with the same rotational speed of the drum 3, the lye container 2 is The aqueous liquid 7 in the movement moves with a different range of action (Ausmaβ). This influence is taken into account in the control device 8 so that the method according to the invention can also be carried out more precisely.

The impedance sensor 10 is arranged in the flush housing 12 as an electrochemical sensor, which is usually an electrode system consisting of a plurality of electrodes, for example two capacitor plates or a three-electrode arrangement. The detergent present in the flushing housing 12 or the aqueous liquid containing it can be analyzed by means of the impedance sensor 10 in order to obtain information on the detergent and at the same time on the design of the washing program.

Furthermore, the washing machine 1 has a lye injection system comprising water connection fittings for the domestic water network 20, an electrically controllable valve 21 and an inlet 13 to the lye container 2, said inlet if necessary It is also possible to pass through the detergent flush housing 12 , from which the water to be injected can transport the detergent portion into the lye container 2 . Furthermore, a heating device 16 for heating the water or washing the lye 7 is located in the lye container 2 . The valve 21 as well as the heating device 16 can be controlled by the control device 8 according to a program schedule, which can be combined with the time program and/or with the lye level, the lye temperature, the rotational speed of the drum, for example, inside the washing machine 1. etc. to combine certain measurements of such parameters.

6 denotes a pressure sensor in the lye container 2, that is, a sensor for measuring the pressure of the hydrostatic pressure. The hydrostatic pressure p results from the level of free rinsing liquid 7 formed in the lye container 2 . Furthermore, the washing machine 1 includes a measuring device 15 for determining the quantity of water charged, for example, a water quantity counter or a flow meter. In the case of a flow meter, the amount of water flowing in is calculated in conjunction with the detected filling time. The flow rate can also be determined by measuring the time until a predetermined level is reached, which corresponds to a determined fixed quantity of water. 18 denotes a lye pump for pumping out the washing lye 7 .

In the figures, 9 designates an electrochemical sensor in the lye container 2 , by means of which various electrochemical measurements, such as voltammetric measurements or impedance measurements, can be carried out. Electrochemical sensors are preferably used as impedance sensors, wherein the structure of the sensor consisting of electrodes and the execution and evaluation of the impedance signals measured by the impedance sensor are not shown in detail here. In order to carry out the method according to the invention, the electrochemical signals of the electrochemical sensor 9 and possibly the impedance sensor 10 as well as the rotational speed of the drum 2, the load of the laundry 4, the pressure of the hydrostatic pressure, etc. and the measured values of the measuring device 15 are provided to the control device 8.

Here, the execution of the method according to the present invention comprises the following steps:

(a) providing the aqueous liquid 7 containing detergent in the lye container 2;

(b) rotating the drum 3 according to a predetermined motion program, the motion program may include different reversing steps, centrifugal dehydration steps under the condition of different rotational speeds of the drum 3 according to the soaking stage, the washing stage or the rinsing stage and many more;

(c) ending the rotational movement of the drum 3 and smoothing the detergent-containing aqueous liquid 7 until a predetermined steady state of the detergent-containing aqueous liquid 7 is reached; and

(d) by receiving and analyzing the electrochemical signal of the electrochemical sensor 9 using the correlation between the electrochemical signal and the detergent concentration, which has been stored in the control device 8, to measure the measurement in step (a) The concentration c _ten of the detergent in the detergent-containing aqueous liquid 7 provided in .

In step (c), the stabilization of the detergent-containing liquid 7 is preferably monitored by means of an electrochemical sensor 9 , wherein in order to determine the predetermined stationary state of the aqueous liquid 7 , preferably by means of cyclic voltammetry, amperometry Alternatively, impedance spectroscopy can be used to perform the measurement.

In step (d), in the embodiment shown here, the measurement of the concentration c _ten of the detergent in the detergent-containing aqueous liquid 7 is carried out by receiving and analyzing an electrochemical sensor functioning as an impedance sensor 9 The impedance signal of 9 is carried out, wherein the correlation between the impedance signal and the detergent concentration already stored in the control device 8 is used.

11 denotes a display device, by means of which the method parameters can be displayed, in particular when the detergent is used optimally (as can be shown by green light-emitting diodes, for example) or when the detergent is not used optimally (eg The progress of the washing programme can be indicated by the red LED). In particular, dosage recommendations can also be displayed to the user of the washing machine.

List of reference signs

1 washing machine

2 lye container

3 rollers

4 laundry

5 drive motor

6 Pressure sensor

7 Aqueous liquids, free rinses, washing lye

8 Controls

9 Electrochemical sensors, such as impedance sensors, in lye vessels; electrode arrangements for measuring impedance

10 Impedance sensor in flush housing; electrode arrangement assembly for measuring impedance

11 Display device

12 (detergent) flush into the shell

13 Input pipe to lye container

14 Laundry carrier

15 Measuring equipment for determining the amount of water charged

16 Heating device

17 Suction device

18 Pump, lye pump

19 Rotation axis

20 Water inlet pipe, domestic water network, water supply device

21 (electrically controllable) valve

22 Temperature sensor

Claims (12)

1. Method for operating a washing machine (1) having:

-a container (2),

-a drum (3) for receiving laundry (4),

-a drive motor (5) for the drum (3),

-an electrochemical sensor (9) in the container (2) for measuring an electrochemical signal related to the composition of the aqueous liquid (7) in the container (2), and

-a control device (8),

it is characterized by executing the following steps:

(a) providing an aqueous liquid (7) containing a detergent in the container (2);

(b) -rotating the drum (3) according to a predetermined movement program;

(c) ending the rotational movement of the drum (3) and smoothing the aqueous detergent-containing liquid (7) until a predefined plateau of the aqueous detergent-containing liquid (7) is reached; and

(d) measuring the concentration c of the detergent in the detergent-containing aqueous liquid (7) provided in step (a)_tenIn such a way that, when the correlation between the electrochemical signal and the detergent concentration stored in the control device (8) is used, the correlation is usedThe electrochemical signal of the electrochemical sensor (9) is received and analyzed,

wherein, as a measure of the steady state, in step (c) a current-voltage curve is received by means of the electrochemical sensor (9) and the current-voltage curve is evaluated with respect to the current contribution which is not caused by diffusion into the electrochemical sensor (9),

wherein, in the step (c):

receiving a cyclic voltammogram and scanning forward to a reverse potential U_λPeak current of time I_pAnd at the reversal potential U_λCurrent of (d)_λAn evaluation of the current contribution not caused by diffusion to the electrochemical sensor (9); or

In the case of the electrochemical sensor (9), a potential step is carried out and the current-time curve obtained in this way is evaluated with respect to the contribution not caused by diffusion as a measure for the lack of smoothness of the aqueous liquid.

2. The method of claim 1, wherein the first and second light sources are selected from the group consisting of,

it is characterized in that the preparation method is characterized in that,

in said step (c), at a predetermined time period Δ t_setSmoothing the aqueous detergent-containing liquid (7).

3. The method of claim 2, wherein the first and second light sources are selected from the group consisting of,

it is characterized in that the preparation method is characterized in that,

in order to determine the time period deltat_setConsider that:

-an amount of aqueous liquid (7),

-amount of washing (4), and/or

-a motion program performed in said step (b),

wherein the interrelationship between the following parameters, which are already stored in the control device (8), is taken into account:

time period Δ t_set，

-an amount of aqueous liquid (7),

-amount of washing (4), and/or

-the motion program performed in said step (b).

4. The method of any one of claims 1-3,

it is characterized in that the preparation method is characterized in that,

the amount or concentration of foam present is taken into account in order to smooth the aqueous detergent-containing liquid until a predefined plateau of the aqueous detergent-containing liquid (7) is reached.

5. The method of claim 4, wherein the first and second light sources are selected from the group consisting of,

it is characterized in that the preparation method is characterized in that,

the presence of foam in the aqueous liquid (7) is determined by means of a hydrostatic pressure sensor (6) and taken into account for determining the stationary state of the aqueous liquid (7).

6. The method according to any one of claims 1 to 3, 5,

it is characterized in that the preparation method is characterized in that,

said steps (c) and (d) are performed in a wetting phase and/or a rinsing phase.

7. The method according to any one of claims 1 to 3, 5,

it is characterized in that the preparation method is characterized in that,

in the case of an asymmetrical shape of the laundry-carrying means (14) used in the drum (3), at least the direction of rotation of the drum (3) is taken into account before a drum standstill phase.

8. The method according to any one of claims 1 to 3, 5,

it is characterized in that the preparation method is characterized in that,

performing step (c) and/or step (d) taking into account the type and/or amount of contamination of the laundry (4),

wherein a correlation between the electrochemical signal and the detergent concentration is stored in the control device (8) for different types and/or amounts of contamination of the laundry (4).

9. The method according to any one of claims 1 to 3, 5,

it is characterized in that the preparation method is characterized in that,

the electrochemical sensor (9) is used as an impedance sensor in step (d).

10. The method of claim 9, wherein the first and second light sources are selected from the group consisting of,

it is characterized in that the preparation method is characterized in that,

receiving an impedance signal by means of the impedance sensor (9), wherein the impedance signal is received and evaluated by applying an alternating voltage having a varying frequency to the impedance sensor (9) and by determining the phase angle of the impedance signal with respect to the impedance

And analyzing and processing in a quantitative aspect.

11. The method of claim 10, wherein the first and second light sources are selected from the group consisting of,

it is characterized in that the preparation method is characterized in that,

the receiving of the impedance signal is carried out with a predetermined frequency of the alternating voltage.

12. Washing machine (1) having:

-a container (2),

-a drum (3) for receiving laundry (4),

-a drive motor (5) for the drum (3),

-an electrochemical sensor (6, 9) in the container (2) for measuring an electrochemical signal related to the composition of the aqueous liquid (7) in the container (2), and

-a control device (8),

it is characterized in that the preparation method is characterized in that,

the control device (8) is provided for executing a method comprising the following steps:

(a) providing an aqueous liquid (7) containing a detergent in the container (2);

(b) -rotating the drum (3) according to a predetermined movement program;

(c) ending the rotational movement of the drum (3) and smoothing the aqueous detergent-containing liquid (7) until a predefined plateau of the aqueous detergent-containing liquid (7) is reached; and

(d) measuring the concentration c of the detergent in the detergent-containing aqueous liquid (7) provided in step (a)_tenIn such a way that the electrochemical signal of the electrochemical sensor (9) is received and evaluated using the correlation between the electrochemical signal and the detergent concentration, which is stored in the control device (8),

wherein, as a measure of the steady state, in step (c) a current-voltage curve is received by means of the electrochemical sensor (9) and the current-voltage curve is evaluated with respect to the current contribution which is not caused by diffusion into the electrochemical sensor (9),

wherein the method comprises the following steps:

receiving a cyclic voltammogram and scanning forward to a reverse potential U_λPeak current of time I_pAnd at the reversal potential U_λCurrent of (d)_λAn evaluation of the current contribution not caused by diffusion to the electrochemical sensor (9); or

In the case of the electrochemical sensor (9), a potential step is carried out and the current-time curve obtained in this way is evaluated with respect to the contribution not caused by diffusion as a measure for the lack of smoothness of the aqueous liquid.

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