EP2038467A1 - Method for handling laundry with a variable wetting duration and corresponding washing machine - Google Patents

Abstract

The invention relates to a method for handling laundry in a washing machine with a water level sensor (15), for determining the hydrostatic pressure (p) of the fluid in the lye container (1). Water is introduced in the lye container to a pre-determined hydrostatic pressure p1 with a preset pressure difference between hydrostatic pressure p1 and a hydrostatic pressure p2. Firstly, (a) water is introduced to the lye container at a hydrostatic pressure below p1 until the hydrostatic pressure p1 is reached and (b) the introduction of water is then stopped until the hydrostatic pressure has dropped to p2. Furthermore, (c) the period tn for the n-th sequence of steps a) and b) is measured and (d) water introduction in step (a) stopped when (d1) the sum of the periods t1 to tn is greater than a given value tmax or (d2) the period tn is greater than a given period tmin. The invention also relates to a corresponding washing machine.

Description

 Process for the treatment of laundry with variable net duration and suitable washing machine

The invention relates to a method for the treatment of laundry with variable network duration in a program-controlled washing machine and a suitable for carrying out this method washing machine. In particular, the invention relates to a method for the treatment of laundry, in which a wetting phase between a predetermined minimum and a predetermined maximum period of time can be made variable.

Reference is made to the prior art to the publications DE 101 36 519 B4 and DE 10 2004 039 662 A1.

In view of the amount of water required for washing for a laundry item in the tub of a program-controlled washing machine, it is desirable to optimize the wetting phase, ie the phase during which the laundry item is wetted with water, so that the laundry items before the actual washing process with a the amount of water adjusted in the shortest possible time completely and evenly wetted.

To carry out the wetting phase, an electromagnetic water level controller (water level sensor) is generally used, which controls the water supply. Here, the supply of water is controlled at a corresponding valve within a level or pressure hysteresis on the water level controller between two switching points. When the valve is open, the tub is filled until an upper switching point (ie upper hydrostatic pressure) P _{1 is} reached. Then the valve is closed and thus the water supply is interrupted. In the wetting phase, the water in the tub is taken up by the laundry to be moistened (to be moistened), so that the hydrostatic pressure in the tub sinks. If a lower switching point (ie lower limit for the hydrostatic pressure) p ₂ is exceeded, the valve is opened again and the water supply to the tub again added. Water is then fed again until the upper switching point is reached, etc.

The duration of the network phase in a washing machine with exclusively electromagnetic water level controller is usually specific for each program step, regardless of the type of loading and load, fixed. This defined fixed duration guarantees in most cases a clear wash, that the necessary amount of water is introduced into the tub of the washing machine. With a badly absorbent laundry item, a water level controller in minus-tolerance or too low a pressure in the public water supply to which the washing machine is connected, the amount of water in the clearing may be too low, and it may lead to a delayed re-drawing of water come.

DE 10 2004 039 662 A1 describes a program-controlled washing machine with a wetting process which can be adapted to the amount of laundry in a laundry drum rotatably mounted in a tub about a non-vertical axis by means of a water supply system and a control device. By the control device, the feed of water into the tub is time controllable, wherein the wetting process in as many phases (Ph1 to Ph3) is divided, as quantity levels (small, medium, large) are provided for the laundry to be treated.

An object of the invention is to provide a method for treating laundry in a program-controlled washing machine with an electromagnetic water level controller, in which the wetting phase can be made flexible and the necessary amount of water for the complete wetting of laundry items for the laundry wash can be better adjusted. The object is also to show a suitable for carrying out this process washing machine.

According to the invention, these objects are achieved by a method having the features of claim 1 and by a washing machine having the features of claim 4. Advantageous embodiments of the invention are listed in the subclaims.

The invention thus relates to a method for the treatment of laundry in a program-controlled washing machine with a tub, a rotatably mounted drum, and a water level sensor for determining the hydrostatic pressure p of the liquid in the tub, in the water via a preset hysteresis the tub up to a predetermined hydrostatic pressure P _{1 is} supplied, wherein the hysteresis is the pressure difference between the hydrostatic pressure P ₁ at the upper switching point for the water supply and the hydrostatic pressure p ₂ at the lower switching point for the water supply, so that first

(A) water is filled at a hydrostatic pressure below P ₁ in the tub (1) until the hydrostatic pressure P _{1 is} reached and then

(B) the water supply is interrupted until the hydrostatic pressure has dropped to p ₂ , wherein the steps a) and b) can repeat, and wherein

(c) measuring in each case the time period t _n for the n-th sequence of steps a) and b), where n is a natural number greater than or equal to 1, and

(D) the water supply according to step (a) is terminated when

(d1) is the sum of the periods ti to t _{n is} greater than a predetermined value t _max, or (d2) the period of time t _n is greater than a predetermined time period t is _mιn.

In the method according to the invention, the value t _min is adjusted so that it is the desired time, which on average according to the suction characteristics different laundry items and the defined hysteresis of the water level controller between two stuffing butts towards the end of the net phase corresponds to needed, corresponds. The value t _max is selected taking into account energy efficiency, time and possible water leaks.

In method step (a) and / or (b), the hydrostatic pressure p measured with the aid of the water level sensor can be compared with the amount of water charged. The laundry in the drum absorbs water, which therefore can not contribute to an increase in the hydrostatic pressure. By comparing the absolute values and, if necessary, the temporal change of measured hydrostatic pressure and amount of water with the values stored in the program control of a washing machine for the corresponding moisture penetration of laundry, corresponding properties (especially size or mass and type of the textiles contained) can be determined. the amount of laundry and its degree of permeability (wetting degree) determine. As a result, the wetting phase can be tuned very precisely to the given batch of laundry.

In process step (a), the supply of water into the tub via a preset hysteresis, preferably via a small hysteresis. "Hysteresis" in the sense of the invention is the pressure difference between the pressure at the upper switching point pi for the water supply and the pressure p ₂ at the lower switching point for the water supply Pa, more preferably from 20 to 100 Pa, and most preferably in the range from 30 to 70 Pa.

If either condition (d1) or condition (d2) has occurred in the process according to the invention, it is generally assumed that the laundry to be treated is sufficiently moistened. In general, it will complete the wetting phase and begin a washing process. However, another method step may initially be carried out, to which then usually a conventional washing process is followed. In particular, according to a further embodiment of the invention, it can be decided on the basis of the size of the laundry item which may be determined in method step (a) and / or (b) whether further treatment steps are carried out. In this case, if necessary, the water supply can also be interrupted.

In an advantageous embodiment of the invention, the drum during the execution of the process steps (a) and / or (b) is rotated, preferably with a number of revolutions of 25 to 50 revolutions per minute (rpm).

In this case, in the presence of a scooping device in a washing machine used for carrying out the method according to the invention, it is advantageous if the direction of rotation of the drum corresponds to a direction of effectiveness of a scooping device. In this case, the laundry is thoroughly moistened, so that the amount of the accumulated water can be determined even more accurately or the wetting can be performed more efficiently.

For the determination of the filled amount of water, a measuring device may be present, for example a time measuring device for determining the opening period of a valve for the inlet of water or a liquid quantity measuring device for measuring the amount of liquid filled.

The invention also relates to a washing machine with a program control for controlling the program flow, a rotatably mounted in a tub drum for receiving laundry, a drive motor for the drum, a water level sensor for determining the amount of liquid in the tub and means for controlling a water inlet wherein the means in conjunction with the water level sensor can perform the method according to the invention described above or one of its developments also described above. Embodiments of the invention are described below with reference to Figures 1 and 2.

Figure 1 is a schematic representation of the time course of a wetting phase in a process for the treatment of laundry. In Fig. 1, this speed and direction of rotation of a drum of a washing machine and the recessed volume of water as a function of time are shown. FIG. 1 illustrates how the times t for the program steps (a) and (b) increase with increasing duration of the wetting phase. In the embodiment of the method shown in FIG. 1, the drum is rotated in different directions for a specific time.

Figure 2 is a schematic representation of the presently relevant parts of a washing machine, in which the method described above can be performed. Other embodiments are conceivable. The washing machine has a tub 1, in which a drum 2 is rotatably mounted and can be operated by a drive motor 14. According to recent findings for ergonomics when dealing with washing machines, the rotation axis 3 of the drum 2 is directed from the horizontal by a small angle (for example 13 °) forwardly upwards, so that one has easier access and insight into the interior of the drum 2. By this arrangement, in conjunction with specially shaped Wäschemitnehmern 4 and 5 Schöpfeinrichtungen for the wash liquor 6 on the inner surface of the drum shell also also an intensification of the flow of the laundry 7 with wash liquor and a reduction of the free liquor reached, ie the amount of wash liquor in the tub which does not touch the saturated laundry and can not be taken up (substantially below the lowest point of the drum 2).

The washing machine also has a liquor inlet system 9, 10, 1 1, which includes a water connection fitting for the domestic water network 8, an electrically controllable valve 9 and a supply line 10 to the tub 1, which may optionally also be guided via a dispenser 1, from the the incoming water Can carry detergent portions in the tub 1. In addition, in the tub 1, a heater 13. The valve 9 as well as the heater 13 can be controlled by a control device or program control 12 in response to a flowchart, the to a time program and / or to the achievement of certain measurements of parameters such as liquor level , Laugentemperatur, rotational speed of the drum, etc. within the washing machine, in particular to the predetermined in the process steps (a) and (b) hydrostatic pressures pi and p ₂ may be bound. 15 denotes a water level sensor for the measurement of the hydrostatic pressure p in the tub 1.

The method has the advantage that even in washing machines with exclusively electromechanical water level controller, the main wash water quantity is not too low despite the tolerance of the water level sensors and the characteristic features of the laundry load in terms of pumping speed and volume at the end of the network phase. The unwanted tightening of water in the heating phase or the washing phase is prevented. The load value, which may possibly be determined via a load detection by comparing hydrostatic pressure and filled amount of water and would be too low for late tightening of water, is better approximated.

In addition, the amount of laundry to be treated can be estimated in a simple and reliable manner in order to adapt the further course of the wetting phase. In particular, it is easy to differentiate between different items of laundry.

Claims

claims 1 . A method for treating laundry in a program-controlled washing machine with a tub (1), a rotatably mounted drum (2) and a water level sensor (15) for determining the hydrostatic pressure p of the liquid in the tub (1), in which process water over a preset hysteresis is supplied to the tub (1) to a predetermined hydrostatic pressure P ₁ , wherein the hysteresis is the pressure difference between the hydrostatic pressure P ₁ at the upper switching point for the water supply and the hydrostatic pressure p ₂ at the lower switching point for the water supply, and in which method first (A) water is filled at a hydrostatic pressure below P ₁ in the tub (1) until the hydrostatic pressure P _{1 is} reached and then (B) the water supply is interrupted until the hydrostatic pressure has dropped to p ₂ , wherein the steps a) and b) can be repeated, characterized in that (c) measuring the time t _n for the n-th sequence of steps a) and b), where n is a natural number greater than or equal to 1, and (D) the water supply according to step (a) is terminated when (d1) the sum of the time periods ti to t _{n is} greater than a predetermined value t _m ax, or (d2) the period t _{n is} greater than a predetermined period t _min . 2. The method according to claim 1, characterized in that the drum (2) during the execution of steps (a) and / or (b) with a number of revolutions of 25 to 50 revolutions per minute (rpm) rotates. 3. The method according to claim 1 or 2, characterized in that the pressure difference between P ₁ and p _{2 is} in the range of 10 to 150 Pa. Washing machine with a program control (12) for controlling the program sequence, a drum (2) rotatably mounted in a tub (1), a drive motor (14) for the drum, a water level sensor (15) for determining the level in the tub (1) and means (9, 10, 12) for controlling a water inlet, characterized in that the means (9, 10, 12) are arranged in connection with the water level sensor (15) for carrying out a method in which water over a preset Hysteresis the tub (1) is supplied to a predetermined hydrostatic pressure P ₁ , wherein the hysteresis is the pressure difference between the hydrostatic pressure pi at the upper switching point for the water supply and the hydrostatic pressure p ₂ at the lower switching point for the water supply, and in which Procedure first (A) water is filled at a hydrostatic pressure below P ₁ in the tub (1) until the hydrostatic pressure P _{1 is} reached and then (b) interrupting the supply of water until the hydrostatic pressure has dropped to p ₂ , whereby steps a) and b) may repeat, (c) measuring the time t _n for the n-th sequence of steps a) and b), where n is a natural number greater than or equal to 1, and (D) the water supply according to step (a) is terminated when (d1) the sum of the periods of time ti to t _{n is} greater than a predetermined value t _max, or (d2) the period t _{n is} greater than a predetermined period t _min .