EP0219387B1 - Method for controlling the liquid level in a tub of a washing machine, and washing machine carrying out the method - Google Patents

Method for controlling the liquid level in a tub of a washing machine, and washing machine carrying out the method Download PDF

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Publication number
EP0219387B1
EP0219387B1 EP86402007A EP86402007A EP0219387B1 EP 0219387 B1 EP0219387 B1 EP 0219387B1 EP 86402007 A EP86402007 A EP 86402007A EP 86402007 A EP86402007 A EP 86402007A EP 0219387 B1 EP0219387 B1 EP 0219387B1
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EP
European Patent Office
Prior art keywords
drum
water
washing machine
friction force
tub
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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
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EP86402007A
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German (de)
French (fr)
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EP0219387A1 (en
Inventor
Laurent Didier
Jean-Claude Geay
Jean-Marcel Duval
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Esswein SA
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Esswein SA
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Priority to AT86402007T priority Critical patent/ATE47166T1/en
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Classifications

    • 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
    • D06F39/00—Details of washing machines not specific to a single type of machines covered by groups D06F9/00 - D06F27/00 
    • D06F39/08—Liquid supply or discharge arrangements
    • D06F39/087—Water level measuring or regulating devices
    • 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
    • D06F2103/18—Washing liquid level

Definitions

  • the invention relates to a method for detecting the level of water in a washing machine tank as well as to a washing machine implementing this method.
  • a washing machine usually has a tub intended to hold the washing or rinsing water, as well as a perforated drum containing the laundry and rotating in the tub.
  • the invention overcomes these drawbacks.
  • the height of water in the tank is determined by determining variations in the torque opposing the rotation of the drum when the latter rotates at constant speed.
  • the invention is based on the observation that, during the rotation of the drum, the friction of this drum and of the laundry against water causes a non-negligible resistant torque and that, in addition, this resistant couple varies with the depth of penetration of the drum. in water.
  • the inertia which is proportional to the acceleration, does not intervene in the measurement of the resisting torque.
  • the constant speed is such that the centrifugal acceleration around the periphery of the basket is greater than the acceleration gravity.
  • the variations in the resistive torque are determined by the variations in the motor torque.
  • the motor torque When the drum is rotated by a universal electric motor, the motor torque, and therefore the resistive torque, can be determined by measuring the intensity of the electric current passing through the motor, the motor torque depending, in this case, directly on this intensity.
  • the resistive torque is determined by this ignition phase angle of the switch.
  • the water introduction solenoid valve is closed, for example, when the increase in resistive torque, from its value before the increase, exceeds a predetermined limit; it is also possible to leave the solenoid valve open for a fixed time after the variation of the friction torque has exceeded this predetermined limit.
  • the latter can be used to determine the water level and control the solenoid valve d 'admission.
  • the program is such that periodically measure the phase angle e, store this angle in memory and compare it with the measurement that was taken at the very start of filling with water, i.e. before the water reaches the bottom of the drum. If the difference exceeds a predetermined value, the solenoid valve is closed or is kept open but only for a determined time.
  • the drum is first rotated, the diameter of which is 40 cm in one embodiment, at a first speed Vi, for example 80 revolutions per minute, and the resistive torque Cr 1 is determined which is stored in memory; then the drum is rotated at a higher speed V 2 , for example 120 revolutions per minute, and I am also on the resistive torque Cr 2 , the time interval separating the second from the first measurement being short enough so that the water height has practically not varied.
  • V 2 for example 120 revolutions per minute
  • I am also on the resistive torque Cr 2 the time interval separating the second from the first measurement being short enough so that the water height has practically not varied.
  • the difference Cr 2 - Cri is only a function of the speed-dependent friction couples, namely the resistance opposed by water and the resistance opposed by air.
  • the difference Cr 2 - Cn represents in practice only the friction of the linen in the water.
  • this difference Cr 2 - Cr 1 is also a function of the water height.
  • the washing machine has a microprocessor it is possible to incorporate in the memory of the latter a table of correspondence between the Cr 2 - Cn values and the water heights.
  • This table can also be incorporated into a memory specially provided for this purpose.
  • the washing machine is for domestic use with a tank 10 (FIG. 3) intended to contain the washing or rinsing water 11 and inside which rotates a perforated drum 12 containing the laundry 13 introduced. before starting the automatic operation of the machine.
  • the motor intended to rotate the drum 12, for example around a horizontal axis 14, is of the universal type with a rotor 15 (FIG. 1) in series with its stator 16 as well as with a triac 17.
  • This motor drives a tachometer generator 18 which delivers a signal representing the real speed of rotation of the motor on an input of a microprocessor 19 which compares this real speed with a reference speed in order to deliver an error signal ⁇ .
  • the latter is used to provide a duration ⁇ , or phase angle, of opening of the triac 17 at each period of the power signal, in general the 220 Volts, 50 Hz sector.
  • the comparison between the actual speed and the speed setpoint has been symbolized by a comparator 20 with an input receiving the signal from the tachometric generator and another input receiving the signal from a memory 21 of speed reference value .
  • the error signal e at the output of comparator 20 acts on the phase angle ⁇ supplied by a generator 22.
  • the output signal ⁇ from the generator 22 is applied to the trigger 23 of the triac 17 via an interface 24.
  • the motor torque Cm being equal to the resistive torque Cr, we can write:
  • the term is the resistant couple due to inertia, which, as we can see (by the term ), is proportional to the acceleration;
  • C f is the part of the resisting torque which is due to friction.
  • the values that periodically takes e, for example every second, and the value e is stored in the memory of the microprocessor 19, which is compared with the value ⁇ 0 previously measured at the start of filling with water, when the level is below the bottom of the drum.
  • the difference between these two measured values e and ⁇ 0 increases with the difference ⁇ C f between the corresponding values of the friction torque Cr.
  • the water supply solenoid valve can be closed as soon as this difference exceeds a predetermined limit; it is also possible to close this solenoid valve only after a time t following the time when the limit is exceeded.
  • This process is based on the observation that the friction torque opposing the rotation of the drum is higher when the drum and the laundry are bathed in water than in the opposite case. In addition, this friction torque increases with the height of water in which the drum plunges.
  • the value e which is taken into account for each measurement is preferably an average of these values for several periods.
  • each measurement corresponds to the average of four successive periods and the average value measurement is repeated every second.
  • the drum is rotated successively at two speeds. For example, the drum spins for five seconds at 80 revolutions per minute, then the next five seconds it spins at 120 revolutions per minute and then repeats the same cycle.
  • a preliminary calibration is carried out which is entered into the memory of the microprocessor in the form of a table of correspondence between the differences ⁇ 1 - 0 2 and the water levels.
  • This process allows, for example, to close the solenoid valve when a desired water height is reached, depending on the load of laundry previously measured by a process such as that described in French Patent 83 16997 in the name of the applicant.
  • Each measurement of the control angle 6 of the switch 17 is preferably equal to the average value over a number of periods T which corresponds to the duration of a complete revolution of the drum or of an entire number of revolutions of this drum.

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  • Engineering & Computer Science (AREA)
  • Textile Engineering (AREA)
  • Control Of Washing Machine And Dryer (AREA)

Abstract

1. A method, utilizing a force couple signal, for ascertaining the level of water in the tub (10) of a washing machine with a perforated drum (12) containing the washing and adapted to rotate within the tub, characterized in that the variations in the friction force couple opposing the rotation of the drum (12) are measured while the frum is turning at constant speed.

Description

L'invention est relative à un procédé de détection du niveau de l'eau dans une cuve de lave-linge ainsi qu'à un lave-linge mettant en oeuvre ce procédé.The invention relates to a method for detecting the level of water in a washing machine tank as well as to a washing machine implementing this method.

Un lave-linge comporte habituellement une cuve destinée à contenir l'eau de lavage ou de rinçage, ainsi qu'un tambour perforé contenant le linge et tournant dans la cuve.A washing machine usually has a tub intended to hold the washing or rinsing water, as well as a perforated drum containing the laundry and rotating in the tub.

Dans les lave-linge à fonctionnement automatique, notamment les lave-linge d'usage domestique, l'eau est introduite dans la cuve par l'intermédiaire d'une électrovanne dont l'ouverture et la fermeture sont commandées en fonction du signal fourni par un détecteur du niveau de l'eau dans la cuve. Habituellement cette détection est effectuée à l'aide d'un composant disposé dans la cuve, le plus souvent un pressostat. Ce composant, qui comporte une chambre fermée par une membrane, est onéreux et son installation complique la fabrication de la machine. Ces inconvénients sont particulièrement gênants pour une fabrication en grande série.In automatic washing machines, in particular domestic washing machines, water is introduced into the tank via a solenoid valve, the opening and closing of which are controlled according to the signal supplied by a water level detector in the tank. Usually this detection is carried out using a component placed in the tank, most often a pressure switch. This component, which has a chamber closed by a membrane, is expensive and its installation complicates the manufacture of the machine. These drawbacks are particularly troublesome for mass production.

L'invention remédie à ces inconvénients.The invention overcomes these drawbacks.

Elle est caractérisée en ce qu'on détermine la hauteur d'eau dans la cuve par détermination des variations du couple s'opposant à la rotation du tambour lorsque ce dernier tourne à vitesse constante.It is characterized in that the height of water in the tank is determined by determining variations in the torque opposing the rotation of the drum when the latter rotates at constant speed.

L'invention repose sur la constatation que, lors de la rotation du tambour, le frottement de ce tambour et du linge contre l'eau provoque un couple résistant non négligeable et qu'en outre ce couple résistant varie avec la profondeur de pénétration du tambour dans l'eau.The invention is based on the observation that, during the rotation of the drum, the friction of this drum and of the laundry against water causes a non-negligible resistant torque and that, in addition, this resistant couple varies with the depth of penetration of the drum. in water.

Il est connu par le brevet US 3 497 884 que le couple s'exerçant sur l'agitateur d'un lave-linge dépend du niveau d'eau et de la quantité de linge dans l'appareil. L'invention se distingue de cet état de la technique par le fait qu'on fait tourner le tambour à vitesse constante et qu'ainsi la variation de couple s'opposant à la rotation du tambour dépend uniquement de la hauteur d'eau, et non de la charge de linge.It is known from US Pat. No. 3,497,884 that the torque exerted on the agitator of a washing machine depends on the water level and the quantity of laundry in the appliance. The invention is distinguished from this state of the art by the fact that the drum is rotated at constant speed and thus the variation in torque opposing the rotation of the drum depends solely on the water height, and not the laundry load.

En effet les variations du couple résistant étant déterminées à vitesse constante de rotation du tambour, l'inertie, qui est proportionnelle à l'accélération, n'intervient pas dans la mesure du couple résistant.Indeed, the variations of the resisting torque being determined at constant speed of rotation of the drum, the inertia, which is proportional to the acceleration, does not intervene in the measurement of the resisting torque.

Afin d'éviter, dans la mesure du possible des variations brusques de couple dues au déplacement périodique du linge dans le tambour, de préférence la vitesse constante est telle que l'accélération centrifuge aux alentours de la périphérie du panier soit supérieure à l'accélération de la pesanteur. Autrement dit:

Figure imgb0001
formule dans laquelle to est la vitesse angulaire du tambour, r le rayon de ce dernier et g l'accélération de la pesanteur.In order to avoid, as far as possible sudden variations in torque due to the periodic movement of the laundry in the drum, preferably the constant speed is such that the centrifugal acceleration around the periphery of the basket is greater than the acceleration gravity. In other words:
Figure imgb0001
 formula in which to is the angular speed of the drum, r the radius of the latter and g the acceleration of gravity.

Dans le cas le plus simple les variations du couple résistant sont déterminées par les variations du couple moteur.In the simplest case, the variations in the resistive torque are determined by the variations in the motor torque.

Lorsque le tambour est entraîné en rotation par un moteur électrique universel le couple moteur, et donc le couple résistant, peut être déterminé par mesure de l'intensité du courant électrique traversant le moteur, le couple moteur dépendant, dans ce cas, directement de cette intensité.When the drum is rotated by a universal electric motor, the motor torque, and therefore the resistive torque, can be determined by measuring the intensity of the electric current passing through the motor, the motor torque depending, in this case, directly on this intensity.

Lorsque le moteur est en série avec un interrupteur commandé et que ce moteur est commandé par une régulation du type à angle de phase le couple résistant est déterminé par cet angle de phase d'allumage de l'interrupteur.When the engine is in series with a controlled switch and this engine is controlled by regulation of the phase angle type, the resistive torque is determined by this ignition phase angle of the switch.

Dans ces dernières réalisations on ne prévoit aucun composant spécifique pour la mesure, car l'intensité ou l'angle de phase est obligatoirement déterminé par le circuit de régulation.In these latter embodiments, no specific component is provided for the measurement, since the intensity or the phase angle is necessarily determined by the regulation circuit.

Quand, au cours du remplissage en eau de la cuve du lave-linge, le niveau de l'eau atteint le fond du tambour le frottement du tambour et du linge dans l'eau commence à intervenir et ainsi le couple résistant à vitesse constante commence à augmenter. L'électrovanne d'introduction d'eau est par exemple fermée quand l'augmentation de couple résistant, à partir de sa valeur avant l'augmentation, dépasse une limite prédéterminée ; il est aussi possible de laisser l'électrovanne ouverte pendant un temps fixé après que la variation du couple de frottement ait dépassé cette limite prédéterminée.When, during the filling of the washing machine tank with water, the water level reaches the bottom of the drum, the friction of the drum and the laundry in the water begins to intervene and thus the resisting torque at constant speed begins to increase. The water introduction solenoid valve is closed, for example, when the increase in resistive torque, from its value before the increase, exceeds a predetermined limit; it is also possible to leave the solenoid valve open for a fixed time after the variation of the friction torque has exceeded this predetermined limit.

Lorsque la commande de l'alimentation du moteur est effectuée par un circuit de régulation, notamment du type à commande par angle de phase, qui comporte un microprocesseur on peut utiliser ce dernier pour déterminer le niveau de l'eau et commander l'électrovanne d'admission. Par exemple le programme est tel qu'on mesure périodiquement l'angle de phase e , on met en mémoire cet angle et on le compare à la mesure qui a été effectuée au tout début du remplissage en eau, c'est-à-dire avant que l'eau n'atteigne le fond du tambour. Si l'écart dépasse une valeur prédéterminée, l'électrovanne est fermée ou est maintenue ouverte mais seulement pendant un temps déterminé.When the control of the motor supply is carried out by a regulation circuit, in particular of the phase angle control type, which includes a microprocessor, the latter can be used to determine the water level and control the solenoid valve d 'admission. For example, the program is such that periodically measure the phase angle e, store this angle in memory and compare it with the measurement that was taken at the very start of filling with water, i.e. before the water reaches the bottom of the drum. If the difference exceeds a predetermined value, the solenoid valve is closed or is kept open but only for a determined time.

Pour obtenir une détermination encore plus précise de la hauteur d'eau dans la cuve du lave-linge on fait d'abord tourner le tambour, dont le diamètre est de 40 cm dans une réalisation, à une première vitesse Vi, par exemple 80 tours par minute, et on détermine le couple résistant Cr1 qu'on met en mémoire ; ensuite on fait tourner le tambour à une vitesse supérieure V2, par exemple 120 tours par minute, et on mesure aussi le couple résistant Cr2, l'intervalle de temps séparant la seconde de la première mesure étant suffisamment court pour que la hauteur d'eau n'ait pratiquement pas varié. Dans ces conditions, la différence Cr2 - Cri est seulement fonction des couples de frottement dépendant de la vitesse, à savoir la résistance opposée par l'eau et la résistance opposée par l'air. Comme le frottement dans l'air a une valeur négligeable par rapport au frottement dans l'eau, la différence Cr2 - Cn ne représente en pratique que le frottement du linge dans l'eau. De plus, comme déjà mentionné, cette différence Cr2 - Cr1 est également fonction de la hauteur d'eau.To obtain an even more precise determination of the height of water in the washing machine tank, the drum is first rotated, the diameter of which is 40 cm in one embodiment, at a first speed Vi, for example 80 revolutions per minute, and the resistive torque Cr 1 is determined which is stored in memory; then the drum is rotated at a higher speed V 2 , for example 120 revolutions per minute, and I am also on the resistive torque Cr 2 , the time interval separating the second from the first measurement being short enough so that the water height has practically not varied. Under these conditions, the difference Cr 2 - Cri is only a function of the speed-dependent friction couples, namely the resistance opposed by water and the resistance opposed by air. As the friction in the air has a negligible value compared to the friction in the water, the difference Cr 2 - Cn represents in practice only the friction of the linen in the water. In addition, as already mentioned, this difference Cr 2 - Cr 1 is also a function of the water height.

Lorsque le lave-linge comporte un microprocesseur il est possible d'incorporer dans la mémoire de ce dernier un tableau de correspondance entre les valeurs Cr2 - Cn et les hauteurs d'eau. Ce tableau peut aussi être incorporé dans une mémoire spécialement prévue à cet effet.When the washing machine has a microprocessor it is possible to incorporate in the memory of the latter a table of correspondence between the Cr 2 - Cn values and the water heights. This table can also be incorporated into a memory specially provided for this purpose.

D'autres caractéristiques et avantages de l'invention apparaîtront avec la description de certains de ses modes de réalisation, celle-ci étant effectuée en se référant aux dessins ci-annexés sur lesquels :

  • - la figure 1 est un schéma d'un moteur universel d'entraînement de tambour de lave-linge avec son alimentation en énergie électrique et sa commande par angle de phase,
  • - la figure 2 est un diagramme montrant les signaux appliqués par la commande par angle de phase du moteur de la figure 1, et
  • - la figure 3 est un schéma de cuve et de tambour de lave-linge.
Other characteristics and advantages of the invention will appear with the description of some of its embodiments, this being carried out with reference to the attached drawings in which:
  • FIG. 1 is a diagram of a universal washing machine drum drive motor with its supply of electrical energy and its control by phase angle,
  • FIG. 2 is a diagram showing the signals applied by the phase angle control of the motor in FIG. 1, and
  • - Figure 3 is a diagram of the tank and washing machine drum.

Dans l'exemple le lave-linge est d'usage domestique avec une cuve 10 (figure 3) destinée à contenir l'eau de lavage ou de rinçage 11 et à l'intérieur de laquelle tourne un tambour perforé 12 contenant le linge 13 introduit avant le démarrage du fonctionnement automatique de la machine.In the example, the washing machine is for domestic use with a tank 10 (FIG. 3) intended to contain the washing or rinsing water 11 and inside which rotates a perforated drum 12 containing the laundry 13 introduced. before starting the automatic operation of the machine.

Le moteur destiné à faire tourner le tambour 12, par exemple autour d'un axe horizontal 14, est du type universel avec un rotor 15 (figure 1) en série avec son stator 16 ainsi qu'avec un triac 17. Ce moteur entraîne une génératrice tachymétrique 18 qui délivre un signal représentant la vitesse réelle de rotation du moteur sur une entrée d'un microprocesseur 19 qui compare cette vitesse réelle à une vitesse de consigne afin de délivrer un signal d'erreur ε. Ce dernier est utilisé pour fournir une durée θ, ou angle de phase, d'ouverture du triac 17 à chaque période du signal d'alimentation, en général le secteur 220 Volts, 50 Hz. Ces diverses opérations sont effectuées grâce à une programmation préalable du microprocesseur 19 ; sur la figure 1 la comparaison entre la vitesse réelle et la vitesse de consigne a été symbolisée par un comparateur 20 avec une entrée recevant le signal de la génératrice tachymétrique et une autre entrée recevant le signal d'une mémoire 21 de valeur de consigne de vitesse. Le signal d'erreur e à la sortie du comparateur 20 agit sur l'angle de phase θ fourni par un générateur 22.The motor intended to rotate the drum 12, for example around a horizontal axis 14, is of the universal type with a rotor 15 (FIG. 1) in series with its stator 16 as well as with a triac 17. This motor drives a tachometer generator 18 which delivers a signal representing the real speed of rotation of the motor on an input of a microprocessor 19 which compares this real speed with a reference speed in order to deliver an error signal ε. The latter is used to provide a duration θ, or phase angle, of opening of the triac 17 at each period of the power signal, in general the 220 Volts, 50 Hz sector. These various operations are carried out thanks to prior programming. microprocessor 19; in FIG. 1, the comparison between the actual speed and the speed setpoint has been symbolized by a comparator 20 with an input receiving the signal from the tachometric generator and another input receiving the signal from a memory 21 of speed reference value . The error signal e at the output of comparator 20 acts on the phase angle θ supplied by a generator 22.

Le signal θ de sortie du générateur 22 est appliqué sur la gachette 23 du triac 17 par l'intermédiaire d'un interface 24.The output signal θ from the generator 22 is applied to the trigger 23 of the triac 17 via an interface 24.

Au début de chaque demi période du signal d'alimentation (figure 2) le triac 17 est bloqué ; ce n'est qu'au bout du temps e qu'un signal de déclenchement est appliqué sur la gachette 23. Le triac 17 reste alors conducteur jusqu'au passage par zéro du courant, c'est-à-dire jusqu'à la fin de la demi période. Plus l'angle e est grand et moins l'intensité du courant fourni au moteur 15 , 16 est impor tante. Cet angle e est fonction du signal d'erreur ε. Cet angle e représente le couple moteur d'entraînement du tambour 12. En effet on sait que le couple moteur Cm fourni par un moteur universel est lié à l'intensité I du courant qui le traverse par la relation suivante:

  • Cm=K(I-lo) (1)
At the start of each half period of the power signal (Figure 2) the triac 17 is blocked; it is only at the end of time e that a trigger signal is applied to the trigger 23. The triac 17 then remains conductive until the current crosses zero, that is to say until the end of the half period. The larger the angle e, the less the intensity of the current supplied to the motor 15, 16. This angle e is a function of the error signal ε. This angle e represents the driving torque of the drum 12. In fact, it is known that the driving torque Cm supplied by a universal motor is linked to the intensity I of the current passing through it by the following relationship:
  • Cm = K (I-lo) (1)

Dans cette formule K et Io sont des constantes.In this formula K and Io are constants.

Par ailleurs, le couple moteur Cm étant égal au couple résistant Cr, on peut écrire :

Figure imgb0002
Dans cette formule le terme
Figure imgb0003
est le couple résistant dû à l'inertie, qui, comme on le voit (par le terme
Figure imgb0004
), est proportionnel à l'accélération ; Cf est la partie du couple résistant qui est due aux frottements.Furthermore, the motor torque Cm being equal to the resistive torque Cr, we can write:
Figure imgb0002
 In this formula the term
Figure imgb0003
 is the resistant couple due to inertia, which, as we can see (by the term
Figure imgb0004
 ), is proportional to the acceleration; C f is the part of the resisting torque which is due to friction.

Si la vitesse de rotation du tambour est constante l'accélération est nulle et le couple résistant n'est dû qu'au frottement. Dans ces conditions :

  • Cf = K (1 - lo) (3)
If the drum rotation speed is constant the acceleration is zero and the resistive torque is only due to friction. In these conditions :
  • C f = K (1 - lo) (3)

Par ailleurs l'intensité I croît avec le complément à 180° (π radians) de θ; on peut donc écrire :

  • I = f (π- θ) (4)
In addition, the intensity I increases with the 180 ° complement (π radians) of θ; we can therefore write:
  • I = f (π- θ) (4)

Dans cette formule f est fonction croissante de x - θ.In this formula f is an increasing function of x - θ.

Ainsi le couple Cf varie dans le même sens que n - 9.Thus the couple C f varies in the same direction as n - 9.

Dans une première réalisation de l'invention on détermine à vitesse constante - au moins égale à celle qui confère une force centrifuge égale à la pesanteur - par exemple 80 tours par minute, les valeurs que prend périodiquement e, par exemple toutes les secondes, et on met en mémoire du microprocesseur 19 cette valeur e que l'on compare à la valeur θ0 précédemment mesurée au début du remplissage en eau, quand le niveau est au-dessous du fond du tambour. L'écart entre ces deux valeurs mesurées e et θ0 croît avec l'écart ΔCf entre les valeurs correspondantes du couple de frottement Cr. L'électrovanne d'alimentation en eau peut être fermée dès que cet écart dépasse une limite prédéterminée; il est également possible de fermer cette électrovanne seulement après un temps t suivant l'instant de détection du dépassement de la limite.In a first embodiment of the invention at constant speed - at least equal to that which gives a centrifugal force equal to gravity - for example 80 revolutions per minute, the values that periodically takes e, for example every second, and the value e is stored in the memory of the microprocessor 19, which is compared with the value θ 0 previously measured at the start of filling with water, when the level is below the bottom of the drum. The difference between these two measured values e and θ0 increases with the difference ΔC f between the corresponding values of the friction torque Cr. The water supply solenoid valve can be closed as soon as this difference exceeds a predetermined limit; it is also possible to close this solenoid valve only after a time t following the time when the limit is exceeded.

Ce procédé est basé sur la constatation que le couple de frottement s'opposant à la rotation du tambour est plus élevé lorsque le tambour et le linge baignent dans l'eau que dans le cas contraire. En outre, ce couple de frottement augmente avec la hauteur d'eau dans laquelle plonge le tambour.This process is based on the observation that the friction torque opposing the rotation of the drum is higher when the drum and the laundry are bathed in water than in the opposite case. In addition, this friction torque increases with the height of water in which the drum plunges.

Pour limiter les risques d'erreur la valeur e qui est prise en considération à chaque mesure est de préférence une moyenne de ces valeurs pour plusieurs périodes. A titre d'exemple chaque mesure correspond à la moyenne de quatre périodes successives et la mesure de valeur moyenne est répétée toutes les secondes.To limit the risk of error, the value e which is taken into account for each measurement is preferably an average of these values for several periods. For example, each measurement corresponds to the average of four successive periods and the average value measurement is repeated every second.

On conçoit qu'avec le moyen de commande de l'électrovanne qui vient d'être décrit il n'est pas nécessaire de prévoir de pressostat ou d'autre moyen de détection du niveau d'eau dans le lave-linge, ce qui réduit sensiblement le coût de fabrication de cet appareil.It is understood that with the control means of the solenoid valve which has just been described it is not necessary to provide a pressure switch or other means for detecting the water level in the washing machine, which reduces significantly the cost of manufacturing this device.

Pour effectuer une mesure encore plus précise de la hauteur d'eau dans la cuve on part de la constatation que le couple de frottement du linge contre l'eau dépend de la vitesse alors que les autres causes de frottement provoquent un couple résistant pratiquement indépendant de la vitesse mais variable avec la charge de linge ou variable d'une machine à une autre. Il est vrai cependant que la résistance de l'air est fonction de la vitesse mais le couple résistant qui en résulte est négligeable par rapport aux autres couples de frottement.To carry out an even more precise measurement of the height of water in the tank, we start from the observation that the friction torque of the laundry against the water depends on the speed while the other causes of friction cause a resistant torque practically independent of speed but variable with the load of laundry or variable from one machine to another. It is true, however, that the resistance of air is a function of speed, but the resulting resistive torque is negligible compared to other friction torques.

Ainsi, pour éliminer de la mesure les contributions indépendantes du frottement du linge dans l'eau, et donc indépendantes de la vitesse, on fait tourner le tambour successivement à deux vitesses. Par exemple, le tambour tourne pendant cinq secondes à 80 tours par minute, puis les cinq secondes suivantes il tourne à 120 tours par minute et recommence ensuite le même cycle.Thus, to eliminate from the measurement the contributions independent of the friction of the laundry in the water, and therefore independent of the speed, the drum is rotated successively at two speeds. For example, the drum spins for five seconds at 80 revolutions per minute, then the next five seconds it spins at 120 revolutions per minute and then repeats the same cycle.

Lorsque le tambour tourne à la première vitesse Vi on détermine l'angle θ1 correspondant (ou sa valeur moyenne sur plusieurs périodes) qui est une fonction du couple de frottement Cfi. On effectue la même mesure de 02 (ou sa valeur moyenne) lorsque le tambour tourne à la vitesse V2 et on met en mémoire la différence θ1 - θ2 qui croît avec la différence entre les couples de frottement intervenant d'une part à la vitesse Vi et d'autre part à la vitesse V2. Cette différence est notée ACf ; elle ne dépend pratiquement que de la hauteur d'eau au-dessus du fond du tambour.When the drum rotates at the first speed Vi, the corresponding angle θ 1 is determined (or its average value over several periods) which is a function of the friction torque Cfi. We carry out the same measurement of 0 2 (or its average value) when the drum rotates at speed V 2 and we store in memory the difference θ 1 - θ 2 which increases with the difference between the friction torques occurring on the one hand at speed Vi and on the other hand at speed V 2 . This difference is noted A C f ; it practically depends only on the height of water above the bottom of the drum.

On effectue un étalonnage préalable qui est introduit en mémoire du microprocesseur sous forme d'un tableau de correspondance entre les différences θ1- 02 et les niveaux d'eau.A preliminary calibration is carried out which is entered into the memory of the microprocessor in the form of a table of correspondence between the differences θ 1 - 0 2 and the water levels.

Ce procédé permet, par exemple, de fermer l'électrovanne lorsqu'est atteinte une hauteur d'eau désirée, fonction de la charge de linge mesurée préalablement par un procédé tel que celui décrit dans le Brevet Français 83 16997 au nom de la demanderesse.This process allows, for example, to close the solenoid valve when a desired water height is reached, depending on the load of laundry previously measured by a process such as that described in French Patent 83 16997 in the name of the applicant.

Chaque mesure de l'angle 6 de commande de l'interrupteur 17 est de préférence égale à la valeur moyenne sur un nombre de périodes T qui correspond à la durée d'un tour complet du tambour ou d'un nombre entier de tours de ce tambour.Each measurement of the control angle 6 of the switch 17 is preferably equal to the average value over a number of periods T which corresponds to the duration of a complete revolution of the drum or of an entire number of revolutions of this drum.

Quel que soit le mode de réalisation adopté il est à souligner qu'avec un lave-linge dont le moteur d'entraînement du tambour est commandé à l'aide d'un microprocesseur une simple programmation supplémentaire du microprocesseur 19 permet de déterminer et commander la hauteur d'eau dans la cuve.Whatever the embodiment adopted, it should be emphasized that with a washing machine whose drum drive motor is controlled using a microprocessor, a simple additional programming of the microprocessor 19 makes it possible to determine and control the height of water in the tank.

Claims (12)

1. A method, utilizing a force couple signal, for ascertaining the level of water in the tub (10) of a washing machine with a perforated drum (12) containing the washing and adapted to rotate within the tub, characterized in that the variations in the friction force couple opposing the rotation of the drum (12) are measured while the frum is turning at constant speed.
2. The method as claimed in claim 1, characterized in that the constant speed is at least equal to the speed at which the centrifugal acceleration at the periphery of the drum is equal to the acceleration due to gravity.
3. The method as claimed in claim 1 or in claim 2 for the ascertainment of the level of water in the tub of washing machine whose drum is driven by a motor (15) with a regulating system characterized in that the friction force couple is measured on the basis of the regulation error signal (e), that is to say the difference between the real speed of rotation of the motor and the command value.
4. The method as claimed in claim 3 for the control of a washing machine whose drum drive motor is placed in series with the switch (17), such as a traic, of a phase angle control system, characterized in that the error signal (ε) acts (22) on the phase, angle (e) and in that the variations in the friction force couple are measured on the variations in the phase angle (e) of the control of the switch (17).
5. The method as claimed in any one of the claims 1 through 4, characterized in that the variations in the friction force couple are measured in the basis of the variations in power supplied to the drive motor (15) of the drum (12).
6. The method as claimed in claim 5, characterized in that the voltage is constant and the motor is preferably a universal motor and the variations in the amperage through the motor are measured.
7. The method as claim in any one of the preceding claims for the ascertainment of the water level in the tub of a washing machine whose drum is driven by a motor whose speed is set by a microprocessor regulation circuit (19), characterized in that a magnitude which is function of the friction force couple is periodically measured, this value is stored in a memory and the stored value at the start of measurement is compared therewith, a variation of this value indicating a variation in the level of the water in the tub.
8. The method as claimed in claim 7, characterized in that the supply of water is interrupted when the difference between the two values exceeds a predetermined limit or is interrupted after a given time elapsing after the detection of the limit being exceeded.
9. The method as claimed in claim 7 or claim 8, characterized in that the average value, taken over several cycles of the cut-off signal, of magnitude representing the friction force couple is periodically measured.
10. The method as claimed in any one of the preceding claims, characterized in that the drum of the washing machine is caused to rotate at a first speed (Vi) during a given time, a magnitude reperesenting the friction force couple opposing the rotation of the drum during this time is measured, the drum is then caused to rotate at a higher speed (V2), and during this time the said friction force couple is measured, the difference between these friction force couples at the second and at the first speed representing the level of water in the drum tub of the washing machine.
11. The method as claimed in claim 10, characterized in that a preliminary sampling operation is performed in such a manner that a memory is loaded with a concordance table between, on the one hand, the difference between the friction force couples at two different speeds and, on the other hand, the water levels.
12. A washing machine with a perforated drum (12) adapted to rotate within a tub (10) and comprising means in order to ascertain the level of water within this tub, such means for ascertaining the water level comprising means to measure variations in the power supplied to the drive motor (15) for the drum (12), when this drum is rotating at a constant speed, such variations representing the variations in the friction force couple opposing the rotation of the said drum.
EP86402007A 1985-09-17 1986-09-12 Method for controlling the liquid level in a tub of a washing machine, and washing machine carrying out the method Expired EP0219387B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT86402007T ATE47166T1 (en) 1985-09-17 1986-09-12 METHOD OF DETECTING THE WATER LEVEL IN A WASHING MACHINE TANK AND WASHING MACHINE FOR CARRYING OUT THESE METHOD.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8513756 1985-09-17
FR8513756A FR2587378B1 (en) 1985-09-17 1985-09-17 METHOD FOR DETECTING THE LEVEL OF WATER IN A WASHING MACHINE AND WASHING MACHINE USING THE SAME

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EP0219387A1 EP0219387A1 (en) 1987-04-22
EP0219387B1 true EP0219387B1 (en) 1989-10-11

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EP (1) EP0219387B1 (en)
AT (1) ATE47166T1 (en)
DE (1) DE3666237D1 (en)
ES (1) ES2000900A6 (en)
FR (1) FR2587378B1 (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
IT1246260B (en) * 1990-07-03 1994-11-17 Zanussi Elettrodomestici WATER LOAD MEASURING DEVICE FOR WASHING MACHINES.

Family Cites Families (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2678051A (en) * 1949-04-08 1954-05-11 Gen Electric Washing apparatus
US3065618A (en) * 1960-08-22 1962-11-27 Whirlpool Co Washing machine having liquid level control means
US3497884A (en) * 1968-02-06 1970-03-03 Whirlpool Co Automatic water level control
AU525345B2 (en) * 1978-04-04 1982-11-04 Tokyo Shibaura Denki Kabushiki Kaisha Automatic washer
DE3101511A1 (en) * 1981-01-19 1982-08-26 Siemens AG, 1000 Berlin und 8000 München METHOD AND ARRANGEMENT FOR DETERMINING THE LOAD OF DEVICES DRIVEN BY AN ELECTRIC MOTOR
FR2524020A1 (en) * 1982-03-26 1983-09-30 Esswein Sa WASHING MACHINE WITH MEANS FOR DETECTION OF BALANCES
AU567432B2 (en) * 1982-05-10 1987-11-19 Matsushita Electric Industrial Co., Ltd. Washing machine
FR2553881B1 (en) * 1983-10-25 1987-11-20 Esswein Sa METHOD FOR DETERMINING A LAUNDRY LOAD IN A ROTATING DRUM, AND WASHING AND / OR DRYING MACHINE USING THE SAME

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Publication number Publication date
DE3666237D1 (en) 1989-11-16
EP0219387A1 (en) 1987-04-22
FR2587378B1 (en) 1987-11-20
ES2000900A6 (en) 1988-03-16
FR2587378A1 (en) 1987-03-20
ATE47166T1 (en) 1989-10-15

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