EP0709512A1 - Method for determining the load level depending on the nature and the quantity of the laundry - Google Patents

Abstract

A process comprises using a washing machine comprising: (a) a rotating drum for the washing, (b) a motor for driving the drum, and (c) a device for the display of a rotation speed signal. The loading stage is determined by an evaluator circuit in accordance with the vibration behaviour of the speed signal during the reversing cycle in a first program cycle. Also claimed is the washing machine.

Description

The invention relates to a method for determining a load level in a washing machine which is dependent on the type of laundry and the amount of laundry. In addition, the invention relates to a washing machine for performing such a method.

It is known to equip washing machines with a so-called economy or 1/2 button. This button causes a special washing, rinsing and spinning program sequence optimized for small quantities. If the user now forgets to press the economy button, a small amount of laundry is inevitably treated with unnecessarily much water and with excessive energy consumption. In addition, with such a button, it is only possible to differentiate between two different loading conditions.

In addition, a method for imbalance detection in household washing machines with a motor for driving the drum and with a device for displaying the motor speed is known, in which a "laundry clumping degree" is inferred from the speed fluctuations occurring during the reversing movements (DE 42 21 772 A1). However, such a degree of laundry clumping cannot be used to evaluate loading levels and to influence the consumption values dependent thereon.

The invention is based on the problem of creating a method which is as precise as possible for determining a loading level which is dependent on the type of laundry and the amount of laundry. According to the invention, this is solved by a method having the features of claim 1.

In an advantageous embodiment of the invention, the evaluation circuit determines the loading level as a function of the vibration behavior of the speed signal when reversing in suction times, with the suction times following individual water inlets at the beginning of the first program section, in particular the pre-wash or main wash cycle. On the one hand, this enables a very early detection of the loading level, and on the other hand the determination of the loading level at this stage is very precise. This is because just not yet completely damp laundry shows a strong dependence of the vibration behavior of the speed signal depending on its weight and on the type of laundry. This is caused by different distribution or clumping of the load, as well as by different friction behavior of the load on the door sealing ring and door sight glass. In addition, at this stage of the washing process, there are no imbalances which are increased by water absorption and which also strongly influence the speed curve.

It has also proven to be advantageous to evaluate the fluctuation range of the speed signal in the steady state. As a result, the transient response dependent on the characteristic of the speed controller, i. H. the first overshoots after the speed increase remain unnoticed. Such an evaluation is therefore possible regardless of the speed controller used.

In addition, it is advantageous to use the suction behavior of the laundry during the suction times and / or the water intake quantity to determine the loading level. This increases the accuracy of the determination of the loading levels.

It is also advantageous to make errors in determining the loading level on the basis of a sensation of the free liquor. In washing machines in which the water level is controlled by an analog level sensor, this can be done by measuring the water level in the steady state, i.e. H. when the laundry is completely damp. In washing machines with conventional switching pressure monitors, the determination of the free liquor can be carried out indirectly by measuring the drop in the alkali temperature following a heating process.

Exemplary embodiments of the invention are illustrated by means of drawings, diagrams and speed measurement curves and are described in more detail below.

Figur 1

eine schematische Darstellung einer Waschmaschine zur Durchführung des erfindungsgemäßen Verfahrens;

Figur 2

ein Blockschaltbild der Bauelemente zur Steuerung und Durchführung des Verfahrens Ermittlung einer von der Wäscheart und der Wäschemenge abhängigen Beladungsstufe;

Figur 3a,b

ein Wasserstands-Zeit-Diagramm und das dazugehörige Drehzahl-Zeit-Diagrammm bei Trommelbeladungen von 2kg und 4kg Baumwollgewebe;

Figur 4 den

Drehzahlverlauf bei einer Waschmaschine während des Reversierens im Hauptwaschprogramm bei Trommelbeladungen von 0 kg, 2,5kg und 5kg Baumwollgewebe;

Show it

Figure 1

a schematic representation of a washing machine for performing the method according to the invention;

Figure 2

a block diagram of the components for controlling and performing the method determining a load level dependent on the type of laundry and the amount of laundry;

Figure 3a, b

a water level-time diagram and the corresponding speed-time diagram for drum loads of 2kg and 4kg cotton fabric;

Figure 4 den

Speed curve for a washing machine during reversing in the main washing program with drum loads of 0 kg, 2.5 kg and 5 kg of cotton fabric;

The washing machine drum (1) in a washing machine for carrying out the method according to the invention is rotatably mounted in the tub (2) in a known manner. It is driven by a motor (3). A tachometer generator (4) coupled to the motor (3) taps an engine speed signal n (t) for control purposes.

To measure the water level, a drain pipe (6) is provided with the drainage area (5) of the tub (2), within which a level sensor (7) is arranged. The fresh water is fed into the tub (2) via a line (8) in which a solenoid valve (9) is located. Solenoid valves (9) with a small volume flow tolerance range are preferably used over the largest possible pressure range. The water supply is shown in simplified form in the drawing, so that only the inflow over the detergent dispenser drawer (10) is symbolized.

The incoming water is heated by a heater (11) in the outflow area (5) of the tub (2), the water temperature being regulated by a temperature sensor (12). For safety reasons, the heating (11) is only switched on after a level N _{max has been} sensed by the level sensor (7). When the water level drops to a level of N _{min, there} is an immediate shutdown. This avoids dry heating.

FIG. 2 shows the interaction of the components for determining the loading level in a block diagram. The central regulating and control element is the control computer µP (13) of the program control device µC (14). It regulates the engine speed, the water temperature and the water level in the tub (2) with the help of control elements (power unit (17), heating relay (18), solenoid valve (9)), depending on the status signals it receives from the sensors (tachometer generator (4), temperature sensor (12), level sensor (7) the regulation or control depends on the program and also on the basis of a so-called loading level, which is essentially characterized by the suction capacity of the laundry, which in turn depends on the type and amount.

Depending on the loading level mentioned above, further program parameters are then set, for example water quantities in individual program sections, the duration of program sections, the number of rinse cycles, spin speeds or unbalance thresholds. In addition, a program dependent on the load level can be selected automatically, which is particularly advantageous for mixed laundry.

The load level is determined via an evaluation circuit (15) integrated in the program control device, which receives the speed signal n (t) during the reversing cycle in a first program section, in particular in the prewash program or in the main wash program, and which determines a value depending on its vibration behavior . In addition to the speed signal n (t), the evaluation circuit (15) can also detect other status signals detected by sensors, such as. B. the switching times of the solenoid valves (9) and the level sensor (7) and temperature values are supplied. Instead of the motor speed, the fluctuation of the motor current can also be evaluated in DC motors. Two exemplary embodiments of the method according to the invention are described below, which are carried out at different phases of such a program section.

In the first exemplary embodiment, the loading stage is determined at the beginning of the first program section, in particular the pre-wash or main wash cycle during the water inlet and the moistening of the laundry. 3a shows a water level-time diagram and the associated speed-time diagram with a drum load of 2 kg of cotton fabric. Figure 3b shows the corresponding diagrams with a load of 4kg cotton fabric. The level is controlled by a switching pressure switch with a switching point N _max and a switching back point N _min . The first run-in takes place from the 0mm level and, as with all subsequent filling steps, with the drum stopped (1). Doing so measured the time t _E1 until the switching point N _{max was reached} . After reaching the switching point, the time t _{E1 is} multiplied by a constant factor F₁ and the duty cycle of the solenoid valve (9) is extended by the time t₁ 'thus obtained. In this way a filling level N _{Ü1.2 is} reached. Then the solenoid valve (9) is closed and the drum (1) rotated. The time from closing the solenoid valve (9) to reaching the downshift level N _min , the suction time t _S1 , is measured and fed to the evaluation circuit. In addition, the evaluation circuit (15) determines the fluctuation range S _{dn of} the engine speed n (t) measured with the tachometer generator (4). The fluctuation range S _dn is understood to mean the standard deviation of the speed signal n (t) in the steady state, ie in the region I shown, ignoring the first overshoots.

In the second filling step, the time t _E2 is measured from the switching on of the solenoid valve (9) at N _min until the switching point N _{max is reached} . In order to reach the filling level N _Ü1.2 again, t _{E2 is} multiplied by a constant factor F₂ and the switch-on time of the solenoid valve (9) is extended by the time t₂ 'thus obtained. Here too, the filling takes place when the drum (1) is stopped. The drum (1) is then rotated and the fluctuation range S _{dn is} determined again and the second suction time t _{S2 is} measured.

abgelegt, aus der die Auswerteschaltung (15) entsprechende Werte abruft. Eine Bestimmung der zugelaufenen Wassermenge V kann über die Summe der Öffnungszeiten t_Ei des Magnetventils (9) oder über einen Wassermengenzähler vorgenommen werden. Anstelle einer Bewertung der zugelaufenen Wassermenge kann diese auch lediglich zur Korrektur einer nach den Saugzeiten ermittelten Beladungsstufe ${\text{B = B(S}}_{\text{dn}}{\text{,t}}_{\text{Si}}\text{)}$

verwendet werden. Auf diese Weise ist die Ermittlung der Beldungsstufe und die hiervon abhängige Weiterführung des Programms schneller möglich. Anstelle der gemessenen Saugzeiten kann bei Verwendung eines hochauflösenden Drucksensors zur Volumenmessung die Änderung des Drucksignals, insbesondere der Gradient des Drucks ausgewertet werden. Hierdurch werden Fehler durch auftretende Hystereseschwankungen bei Drucksensoren vermieden.Following the second filling step, the evaluation circuit (15) determines the loading level as a function of the fluctuation range S _dn , the suction times t _S1 and t _S2 and the total amount of water supplied. For this purpose, there is a table (16) with loading levels in a memory (16) created with a fuzzy logic algorithm ${\text{B = B (S}}_{\text{dn}}{\text{, t}}_{\text{Si}}\text{, V)}$

stored, from which the evaluation circuit (15) retrieves corresponding values. The amount of water V supplied can be determined via the sum of the opening times t _{Ei of} the solenoid valve (9) or via a water meter. Instead of evaluating the amount of water that has flowed in, it can only be used to correct a loading level determined according to the suction times ${\text{B = B (S}}_{\text{dn}}{\text{, t}}_{\text{Si}}\text{)}$

be used. In this way, the determination of the registration level and the dependent continuation of the program is possible faster. Instead of the measured suction times, the change in the pressure signal, in particular the gradient of the pressure, can be evaluated when using a high-resolution pressure sensor for volume measurement. This avoids errors caused by fluctuations in hysteresis in pressure sensors.

When looking at diagrams 3a and 3b, it is noticeable that the fluctuation range Sdn increases with the amount of loading and the suction times decrease. In the ongoing program, the loading level value determined in this way is corrected on the basis of a calculation of the free fleet. In washing machines with analog level sensors (7), this is possible directly by measuring the water level. In washing machines with switching pressure switches, the cooling rate of the wash liquor is an indication of the amount of free liquor. The load level determined is used, as already described, to influence program parameters.

In the second embodiment, the vibration behavior of the speed signal is processed after the water running-in phase. Figure 4 shows the speed curve in a washing machine during reversing in the main washing program with different loads. The evaluation circuit (15) evaluates the overshoots when the speed increases after the reversing pause, the overshoots in the reversing pause, the fluctuation range and their changes over time with known control characteristics. A closer look reveals that the speed behavior has the following characteristics:

Drum (1) empty

• no overshoots when the speed increases after the reverse pause
• uniform fluctuation range
• small fluctuation range
• no overshoot in the reversing break

Partial load (2.5 kg terry)

• small overshoots when the speed increases after the reverse pause
• uneven fluctuation range
• Fluctuation range higher than with an empty drum (1)
• high overshoot in the reversal break

Full load (5 kg terry cloth)

• hohe Überschwinger beim Drehzahlanstieg nach der Reversierpause
• ungleichmäßige Schwankungsbreite
• Schwankungsbreite geringer als bei Teilbeladung
• hohe Überschwinger in der Reversierpause

Die Auswertung der vorgenannten Charakteristika bieten den Vorteil, daß hierbei außer dem Drehzahlverhalten keine zusätzlichen Meßgrößen erforderlich sind.

• high overshoots when the speed increases after the reverse pause
• uneven fluctuation range
• Fluctuation range less than with partial loading
• high overshoot in the reversal break

The evaluation of the above-mentioned characteristics offers the advantage that no additional measured variables are required in addition to the speed behavior.

Claims (12)

Method for determining a load level dependent on the type of laundry and the amount of laundry in a washing machine with a rotatable drum for receiving laundry, with a motor for driving the drum and with a device for displaying a speed signal dependent on the motor speed, in particular with a tachometer generator for display the motor speed or with a measuring resistor for displaying the motor current, an evaluation circuit determining the loading level as a function of the vibration behavior of the speed signal during the reversing cycle in a first program section, in particular in the prewash program or in the main wash program. Method according to claim 1,
characterized,
that the evaluation circuit determines the loading level on the basis of the fluctuation range and the overshoot in the reversing pause and when the speed increases after the reversing pause, taking into account the characteristics of the speed controller. Method according to claim 1,
characterized,
that the evaluation circuit determines the loading level as a function of the vibration behavior of the speed signal when reversing in suction times, the suction times following individual water inlets at the beginning of the first program section, in particular the pre-wash or main wash cycle. Method according to claim 3,
characterized,
that the fluctuation range of the speed signal is evaluated in the steady state. Method according to one of claims 1 to 4,
characterized,
that the duration of the suction times is used to determine the loading level. Method for determining a load level dependent on the type of laundry and the amount of laundry, in particular according to one of Claims 1 to 5, using a high-resolution level sensor, characterized in that the change in the level signal is used to determine the load level. Method according to one of claims 1 to 5,
characterized,
that the water intake quantity is used to determine the loading level. Method according to claim 7,
characterized,
that the correction of an already determined loading level is carried out with the help of the run-in ones. Method according to one of claims 1 to 6, wherein a high-resolution level sensor is used for water level control,
that the loading level is corrected on the basis of the water level after the last water inlet at the beginning of the first program section, in particular the pre or main wash cycle. Method according to one of claims 1 to 6,
characterized,
that a correction of the loading level is carried out on the basis of a measurement of the drop in the alkali temperature following a heating process. Method according to one of claims 1 to 8,
characterized,
that the loading level is used to determine program parameters, for example the amount of water in individual program sections, times for individual program sections, the number of rinse cycles, spin speeds and unbalance thresholds. Washing machine for carrying out a method for determining a loading level dependent on the type of laundry and the amount of laundry according to one of claims 1 to 9.

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