EP2044252B1 - Method for treating laundry as well as a program-controlled washing machine suitable for this purpose - Google Patents

Description

The invention relates to a method for treating laundry in a program-controlled washing machine and to a washing machine which is particularly suitable for carrying out this method. In particular, the invention relates to a method for treating laundry with a wetting phase, in which the addition of water can be controlled by comparing measured values with predetermined threshold values.

When adjusting the amount of water required for washing in program-controlled washing machines especially the wetting phase should be optimized so that each batch of laundry is wetted completely and evenly with a coordinated amount of water in the tub before the actual washing process in the shortest possible time.

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

EP 0644 291 A1 discloses a method in which the amount of laundry is determined on the dripping behavior of the laundry. Here, a lot of water is poured into the liquor and then alternately operated and stopped. The quantities of water squeezed out during drum standstill times are measured, and from this, as well as the dripping speed, the amount of laundry is calculated.

A similar procedure is in DE 195 38 2912 A1 disclosed. This document describes a method for determining the water absorption level of laundry in a washing machine. Here, a predetermined amount of water is first filled and then moved the drum. At the end of the movement phase and at the end of a rest period, the respective water levels are measured. The Difference in water levels is determined and used to determine absorbency.

Although the latter two methods are suitable as an additional method to determine the absorbency of laundry, but not as a load measurement method, since they can be applied relatively late in the wash cycle, namely after completion of the water supply.

The previously known wetting processes or phases must therefore be further optimized. For example, the known wetting processes still do not take into account laundry items of varying sizes, so that at very large batches of laundry (i.e., laundry items near the loading limit), there is no complete wetting. In contrast, the wetting phase for small items of laundry often takes too long, measured by their wetting success. In addition, in the known wetting processes, the uniformity of wetting can be further improved.

The object of the invention was therefore to provide a method for treating laundry in a program-controlled washing machine, in which the wetting phase can be controlled so that a laundry item is detected quickly and accurately.

It was also an object to show a suitable washing machine for carrying out this method.

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

The invention thus relates to a method for treating laundry in a program-controlled washing machine with a sensor for determining a level of the liquid in the tub (ie the hydrostatic pressure p), the sensor signal is recorded during the process, and a drum, wherein in one step a) in a wetting phase during rotation of the drum water until a predetermined threshold for the hydrostatic pressure p and until reaching a predetermined threshold for the time gradient (Δp / Δt) of the hydrostatic pressure p is filled into the tub.

In a preferred embodiment, additionally as process step b) the rotation of the drum and the filling of water are stopped at a given time in the process and the change of the hydrostatic pressure p due to returning water is evaluated to determine a loading amount. Here, e.g. the methods known in the art are used.

In method step a), the hydrostatic pressure p measured with the aid of the sensor can be compared with the filled-in amount of water q. The laundry in the drum absorbs water, which therefore can not contribute to an increase in the hydrostatic pressure. By comparing the measured hydrostatic pressure and the accumulated amount of water - the absolute values p, q and the temporal change (Δp / Δt) - with corresponding values stored in the program control of a washing machine for moisture washing, the batch of laundry can be compared in amount, determine its pumping speed and its degree of moisture penetration (degree of wetting). As a result, the duration of the wetting phase and the amount of water required for wetting can be tailored very precisely to the given amount of laundry.

According to the invention, it is essential in process step a) that water is introduced until a predetermined threshold p ₁ for the hydrostatic pressure p and a predetermined threshold value (Δp / Δt) ₁ for the temporal gradient of the hydrostatic pressure p is reached. This will generally signal to the program a sufficient wetting of the laundry cost, so that the actual washing can begin.

It can be done in the further filling of water in the tub via a preset hysteresis, preferably via a small hysteresis. "Hysteresis" within the meaning of the invention is the pressure difference between the pressure at the upper switching point for the water supply and the pressure at the lower switching point for the water supply. In the present invention, it is preferable that this pressure difference (hysteresis) is in the range of 10 to 150 Pa, more preferably 20 to 100 Pa, and most preferably in the range of 30 to 70 Pa.

When using the method step b), the predetermined time t ₁ is generally oriented to certain, with respect to the distinctness of the laundry charges as critical to be classified points. Such a time is achieved, for example, when actually provided in a method for treating laundry that for a given loading level (amount of Wäschegut) water quantity q is _imit achieved. Accordingly, in embodiments of the invention, provision may be made for method step b) to be carried out at a plurality of times (t ₁ , t ₂ , t ₃ , etc.).

The method step b) is based on the fact that with increasing saturation of the laundry with water more relatively free water is present, which can run back relatively quickly due to gravity from the laundry in the tub. Thus, when the drum is at a standstill, by tracking the time change of the hydrostatic pressure p, it is possible to detect the load of laundry and its wetting or to correct an already recognized load. This can be done for example by comparing the present after a certain time hydrostatic pressure p with a predetermined value. The hydrostatic pressure p determined in this way can preferably be used to vary or adapt the further load-dependent parameters of the wetting phase and / or of the further program sequence. If the comparison of the present in step b) after a certain time hydrostatic pressure p with a predetermined value indicating a not yet sufficient wetting of the laundry, in particular more predetermined thresholds p ₂ , p ₃ , etc. for the hydrostatic pressure p and other predetermined Threshold values (Δp / Δt) ₂ , (Δp / Δt) ₃ , etc. for a method step a) following the method step b) or a further time t ₂ , t ₃ , etc. for a next critical point of a next larger loading stage or selected.

In the case of carrying out process step b), with the result that the predetermined value for a certain hydrostatic pressure is not reached, it is preferred according to the invention that the drum is rotated for a few seconds to minutes, preferably at a speed, before the re-water inlet from 10 to 50 revolutions per minute. As a result, the freed water is re-entered into the laundry.

According to the invention, it is preferred if both process steps a) and b) are carried out. In such a case, even in process step a) the filled Amount of water q measured, and the step a) ends when the amount of water q _limit actually provided for a specific loading stage (amount of laundry) is reached for the treatment of laundry. According to the invention, the water retention capacity of the laundry is therefore preferably used in addition to the suction capacity of the laundry for the determination of criteria for controlling the network phase.

In the method according to the invention, the drum is preferably rotated in a certain direction.

If, in the process according to the invention, water has been introduced until the conditions according to the invention according to steps a) and b) are present, it is generally assumed that the laundry to be treated is thoroughly moistened.

If water has been added until the conditions specified for process step a) and / or b) are present, the wetting phase will generally be completed and a washing process started. However, other method steps, for example, a soaking of the laundry for a predetermined period of time without drum movement done, are performed, which then usually followed by a conventional washing process.

In particular, according to a further embodiment of the invention, it can be decided on the basis of the size of the laundry lot optionally determined in process steps a) and / or b) that further special wetting steps or other treatment steps follow, possibly with reversing drum movement. In this case, if necessary, the water supply can also be interrupted.

In an advantageous embodiment of the invention, the direction of rotation of the laundry drum corresponds to the direction of the effectiveness of a scooping device. Here, the laundry is thoroughly moistened, so that the amount of the accumulated water can be determined more accurately.

For the determination of the filled amount of water q may be provided a measuring device, for example a time measuring device for determining the opening period of an inlet valve for the 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, a drive motor for the drum, a sensor for determining the height of the liquid in the tub and switching means for rotating and stopping the drum the switching means and the sensor can perform the method of the invention.

In particular, the program control comprises storage means in which the threshold value or threshold values p _x , the threshold value or the threshold values (Δp / Δt) _x for the time gradient of the hydrostatic pressure p and the predetermined amounts of water for the respective loading stages are stored. Particularly advantageously, the values can be stored in tabular form, wherein a threshold value p _x for the hydrostatic pressure p and a threshold value (Δp / Δt) _x for the time gradient of the hydrostatic pressure p are assigned to a given amount of water. Advantageously, these values are sorted in an ascending order relative to values of the given amount of water. Thus, the thresholds during a filling operation with a steadily increasing amount of water can be easily read from the table sequentially. In addition, the program control has at least one comparison device, which has a measured hydrostatic pressure p, whose temporal change (Δp / Δt) and / or a supplied water quantity q with one of the variables associated limit values p _x , (Δp / Δt) _x and q _{Limit x can} compare and which can generate a signal when exceeded. With such a signal, the switching means for controlling the wetting phase can be influenced. The index x denotes a particular value from a selection of several possible values.

Furthermore, the washing machine in a preferred embodiment comprises at least one of the above-mentioned measuring devices for determining the amount of water q filled.

• Figur 1: eine schematische Darstellung der für die Erfindung relevanten Teile einer Waschmaschine,
• Figur 2: ein schematisches Diagramm eines zeitlichen Ablaufs der Trommeldrehzahl n (Linie 18) und der eingefüllten Wassermenge q (Linie 19) einer erfindungsgemäßen Benetzungsphase umfassend mehrere Verfahrensschritte a) und b),
• Figur 3: eine schematische Darstellung zeitlicher Verläufe des hydrostatischen Druckes p für Benetzungsphasen von unterschiedlichen Wäschemengen und
• Figur 4: eine schematische Darstellung eines zeitlichen Verlaufs des hydrostatischen Drucks p (durchgezogene Linie) und dessen zeitliche Änderung (gestrichelte Linie) während eines Verfahrensschritts a).

The invention is illustrated in more detail below with reference to the figures, in which:

• FIG. 1 : a schematic representation of the relevant parts of the invention for a washing machine,
• FIG. 2 FIG. 2: shows a schematic diagram of a time sequence of the drum speed n (line 18) and the amount of water q (line 19) of a wetting phase according to the invention comprising a plurality of method steps a) and b),
• FIG. 3 : A schematic representation of temporal curves of the hydrostatic pressure p for wetting phases of different amounts of laundry and
• FIG. 4 : A schematic representation of a time course of the hydrostatic pressure p (solid line) and its temporal change (dashed line) during a process step a).

FIG. 1 is a schematic representation of the relevant parts of the invention for a washing machine, in which a method according to the invention can be carried out. Other embodiments are conceivable. The washing machine of the FIG. 1 embodiment shown has a tub 1, in which a drum 2 rotatably mounted and can be operated by the drive motor 14. According to recent findings for the ergonomics in dealing with such washing machines, the axis of rotation 3 of the drum 2 from the horizontal by a small angle (eg 13 °) directed forwardly upwards so that you have 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 achieved, ie the amount of wash liquor in the tub which can not be absorbed by the saturated laundry (substantially below the lowest point of the drum 2). The invention is not limited to a washing machine with such an inclined drum axis, but can also be used in other washing machines with a rotatable in a tub, in particular about a substantially horizontal axis rotatably arranged drum.

The washing machine also has a liquor inlet system comprising 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 Waschmitteleinspüleinrichtung ("Einspülschale") 11, from which the feed 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 ("program control") 12 in response to a program flowchart of a time program and / or the achievement of certain measurements of Parameters such as liquor level, liquor temperature, speed of the laundry drum, etc. within the washing machine, in particular to the thresholds specified in the method steps a) and / or b) may be bound. 15 means a sensor for the measurement of the hydrostatic pressure p in the tub 1. The hydrostatic pressure p results from the level height H of forming in the tub 1 free fleet. In addition, the washing machine comprises a measuring device 16 for determining the amount of water q filled. It can be designed, for example, as a water meter or as a flowmeter. In the case of a flowmeter, the amount of water q is calculated in conjunction with a detected filling time. It is also conceivable to determine the flow by measuring the time to reach a predetermined level height, which corresponds to a certain fixed amount of water. The signal of the measuring device 16 is supplied to the control device 12.

The invention has numerous advantages. With the method according to the invention, it is possible to estimate the amount of laundry to be treated in a simple and reliable manner in order to adapt the further course of the wetting phase to it. In particular, it is easy to differentiate between different loadings or loading stages.

In one embodiment, as in FIG FIG. 2 shown at the beginning of a wetting phase A of the process step a) (phase B) during a continuous rotation of the drum 2 at a rotational speed n1, preferably at a rotational speed of 10 to 50 revolutions per minute, water supplied to the tub 1. The direction of rotation of the drum 2 is in an optimal direction for the scooping device 5 17, whereby the present in the tub water 6 is returned to the drum 2. During the phase B, the detected values for hydrostatic pressure p, their temporal change (Δp / Δt) and the amount of water q supplied are measured and with respective associated limit values p ₁ , (Δp / Δt) ₁ and q _{limit 1} , which for a a small load of normal absorbency apply, compared. For such a comparison, the control device 12 comprises a comparator 121 to which the measured values and the limit values are supplied. at If one and / or more limit values are exceeded, the comparator 121 can generate a signal which is used to further control the method and / or the further program sequence.

In an alternative embodiment, the rotation of the drum 2 is reversing. Such a design is used in particular for washing machines that have no scooping device 5.

During the filling of the water, the hydrostatic pressure p increases depending on the laundry load 7 and its pumping speed. Depending on the actual laundry load 7, its pumping speed and the geometrical dimensions of the tub 1 and the drum 2, the time change (Δp / Δt) of the hydrostatic pressure p varies. An example is in FIG. 4 shown. Only at the time t (Δp _/ Δt) ₁ , both the hydrostatic pressure p exceed the threshold value p ₁ and the time change (Δp / Δt) of the hydrostatic pressure p exceed the threshold value (Δp / Δt) ₁ . If these two threshold values are reached before the water quantity q _limit prescribed for wetting the small loading stage has been reached, the method step a) or the phase A is ended since the achievement of the two threshold values indicates that the laundry load 7 is sufficiently wetted. A washing phase D can now be connected directly to phase A. Such a process occurs when in fact a small load of laundry 7 has been introduced into the drum 2.

If the laundry load 7 is more absorbent than assumed, or if a larger laundry load 7 is present, the amount of water q q previously reached the limit q _{limit 1} , which was set for a small loading quantity, ie, it is a first critical point for the distinctness, the time t ₁ , reached. Thus, process step b) (phase C) begins. Turning the drum 2 and filling the water are stopped. Now, when the drum 2 is at a standstill, the hydrostatic pressure p or its temporal change (Δp / Δt) is tracked. The comparison of the present after a certain time hydrostatic pressure p with a predetermined value checked on the one hand in the process step a) determined wetting degree of the laundry 7 and on the other hand, a previously determined amount of laundry charge and / or their pumping speed can be determined more accurately. If the comparison reveals that sufficient wetting of the laundry 7 has not yet taken place, the drum 2 is again rotated in order to release the released water 6 into the laundry load 7 due. Preferably, the drum 2 is driven with the suitable speed for scooping n1 in continuous rotation in the direction of the arrow 17.

After a short period of time, a process step a) (phase B ') is followed again and the wetting phase is prolonged. The prolonged wetting phases are in FIG. 2 For the phase B 'the limits p ₂ , (Δp / Δt) ₂ and q _{limit 2} , which apply to a normal absorbency for an average load, are fixed, ie a second one for distinctness The critical point reached with time t ₂ is selected, and the phase B operation described above repeats itself correspondingly in phase B '.

If, in the phase B ', the limit value q _{limit 2} set for a medium load of laundry is reached first or if a larger or more absorbent laundry load is found in a subsequent process step b) (phase C') than for average normally absorbent laundry load further method steps b) and a), for example phase B ", in which the limit values p ₃ , (Δp / Δt) ₃ and for a given amount of water a limit value q _{limit 3 are} specified, which apply to a normal absorbency for a large load quantity.

In order to avoid an overfilling of water, the measured amount of water is compared with a maximum predetermined amount of water q _{limit max} , which must not be exceeded during the wetting phase. When the maximum amount of water q _{limit max} reached during the wetting phase is reached, the filling of water and the active wetting phase are stopped. This is followed by the normal washing phase D. In the washing phase D can, as in Fig.2 shown, the drum 2 are operated at a suitable speed for washing n ₂ , which is higher than the speed n _{1 of} the wetting phase. During the washing phase D, further filling of water may be provided via a preset hysteresis.

An example of a time course of the hydrostatic pressure p is in FIG. 3 shown. The course corresponds to the in Fig. 2 shown progressions of the wetting phases A, A 'and A " Fig. 3 each course for a small (1 kg), a medium (3 kg) and large (6 kg) loading stage.

With the method according to the invention, the wetting phase can be automatically adapted to the amount of laundry of a laundry item, so that at uniform wetting the laundry is wetted before the actual washing process with the optimum amount of water or alkali.

The inventive method for wetting laundry is equally suitable for wetting of dry laundry at the beginning of a wash cycle as well as for wetting wet laundry at the beginning of a rinse cycle. Deviating limit values or threshold values may be specified for the latter case.

Claims (5)

1. Method for treating laundry in a program-controlled washing machine with a sensor (15) for determining a level of the liquid located in the wash container (1), the sensor signal of which being registered during the method, with a drum (2) and with a program controller (12),
   characterised in that in a wetting phase

   a) during the rotation of the drum (2) water is filled in in a quantity q until a predefined threshold value (p₁, p₂, p₃) for the hydrostatic pressure p is reached and until a predefined threshold value ((Δp/Δt)₁, (Δp/Δt)₂, (Δp/Δt)₃) for the temporal gradient of the hydrostatic pressure p is reached and a comparison of the measured hydrostatic pressure p, the filled-in water quantity q and the change over time (Δp/Δt) is performed with corresponding values stored in the program controller (12).
2. Method according to claim 1, characterised in that in addition

   b) at a point in time (t₁, t₂, t₃), when the filled-in water has reached a predefined quantity (q_{limit 1}, q_{limit 2}, q_{limit 3}) for a predefined loading level, in the method the rotation of the drum (2) and the filling in of water are ended and the change in the hydrostatic pressure p is evaluated on the basis of released water for determining a loading quantity.
3. Method according to one of the preceding claims, characterised in that the drum (2) is rotated for a few seconds or minutes at a rotational speed of from 10 to 50 rotations per minute before water is let in once again.
4. Method according to one of the preceding claims, characterised in that the method step a) and/or the method step b) is/are repeated.
5. Washing machine with a program controller (12) for controlling the program sequence, a drum (2) rotatably mounted in a wash container (1), a drive motor (14) for the drum, a sensor (15) for determining the level (H) of the liquid (6) located in the wash container (1), switching means (9, 12, 14) for rotating and stopping the drum (2),
   characterised in that
   the program controller (12) is configured to perform the method according to one of the preceding claims.

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