EP3077580B1 - Method for treating laundry with an improved wetting phase, and washing machine suitable for this purpose - Google Patents

Description

The invention relates to a method for treating laundry in a washing machine with an improved wetting phase and a washing machine suitable for this purpose. In particular, the invention relates to a method for operating a washing machine for treating laundry with a drum rotatably mounted in a tub, a drive motor for the drum, a control device, a water supply system, a measuring device for determining an amount of aqueous liquid introduced into the tub, one Heating device for heating the aqueous liquid in the tub and a temperature sensor, as well as a washing machine particularly suitable for this.

In a washing process in a washing machine, a wetting phase takes place before the actual washing phase, in which the dry laundry items are wetted with water or wash liquor. This is usually followed by heating to a desired washing temperature and the actual washing phase begins.

However, it should be taken into account that a washing process in a washing machine should be as energy efficient as possible. Since the heating of the water used in particular uses a lot of energy in a washing process, it is desirable to reduce the energy to be used for this.

The energy used in a washing process is used in particular to heat the water used for the actual washing phase. Energy is also used to control the washing machine, to operate a drain pump and to drive the drum. In order to meet demands for a further reduction in the energy to be used in a washing process, it is therefore desirable to reduce the amounts of energy required for these steps.

It would therefore be desirable to provide an energy efficient method for treating laundry in a washing machine in which laundry is to be washed if possible at a predetermined washing temperature, in particular also at a high washing temperature such as 60 ° C, can be treated.

The DE 10 2005 012 426 A1 describes a wetting process for laundry in a program-controlled washing machine, which can be matched to the amount of laundry in a laundry drum rotatably mounted in a tub around a non-vertical axis by means of a water feed system and a control device by means of which the inflow of water into the tub can be timed, and which begins in a first phase (Ph1) with an inflow of a first measured amount of water into the tub with the laundry drum at rest or rotating continuously. The washing drum is driven in the first phase (Ph1) with the addition of water at least essentially continuously until essentially no more suction behavior can be determined based on the measurement signals about the amount of water flowing in, and in a second phase (Ph2) at least in Mainly driven continuously and a further amount of water filled in until the level in the tub is affected by the water level curve recognized in the first phase (Ph1) in relation to the maximum height and rate of change of the water level (N) and in terms of falling back due to the water being sucked in has determined the laundry or has reached a water level that is adapted to the water level curve recognized by an expert system within the second phase (Ph2) when the laundry is filled and sucked in water.

The DE 10 2006 029 670 A describes a method for treating laundry with variable network duration and a washing machine suitable for this.

The DE 10 2007 033 493 A describes a method for treating laundry and a program-controlled washing machine suitable for this purpose, wherein, among other things, the laundry is wetted with an amount of water which is less than the amount of water required to saturate the laundry with water. Then a foam is generated, heated and the laundry washed with it.

The DE 196 20 512 A describes a program-controlled washing machine with control elements for setting washing programs that can be distinguished at least in temperature, with the control elements being an automatically running hygiene program can be selected, which includes heating the washing liquid to a predetermined minimum value, then cooling the washing liquid by adding cold water and pumping off the cooled washing liquid.

The U.S. Patent 4,794,661 describes a method for treating laundry in a drum of a washing machine rotatably mounted in a tub before the start of a washing program. Here, from a hot water reservoir located outside the washing machine, water is poured into the tub until it is partially filled to wet the laundry in the drum, the drum is rotated and the water in the washing machine is circulated to the laundry in the drum to preheat the drum and the tub, so that no subsequent cooling of the washing liquor takes place during a subsequent addition of detergent and an ongoing washing phase.

The DE 10 2007 037 159 A1 describes a method for washing laundry in a washing machine with a tub, in which a drum is rotatably mounted, with the phases washing (WA), in which the predetermined amount of water is heated to a predetermined temperature (T1), rinsing (Ri) and Final spin (FS), the washing phase (WA) comprising a first section (WA1) which is carried out with a first amount of water at the predetermined temperature (T1), followed by a second section (WA2) in which an additional amount of water is added to the first amount of water, the increased amount of water in the second section being heated to another predetermined temperature (T2).

The DE 10 2012 023 084 A1 describes a method for washing laundry items in a program-controlled domestic appliance for the care of laundry items, in which a washing liquid present in a tub is heated, a washing temperature is set, laundry-specific and / or device-specific parameters are recorded and, depending on the parameters, the heating of the washing liquid Setting a specific target temperature (Tz) is carried out. During the wetting phase (A2), in which washing liquid is supplied to the tub for wetting the laundry items, a heating device for heating the washing liquid is activated and the washing device is heated with the heating device Mains phase temperature (Tn) is heated, which is lower than the target temperature (Tz), which is assigned to a washing method selected by an operator.

The DE 197 30 422 A1 describes a method for wetting laundry in a program-controlled drum washing machine for the home, the washing drum of which is rotatably arranged in a tub, which is equipped with a fresh water supply, a water level regulator and a detergent dispenser. The washing drum with the dry laundry is first brought up to a rotational speed forming a laundry ring, the washing drum is then stopped and then wetting liquid and optionally detergent are added. The free liquor in the bottom of the lye tub is heated to a predetermined temperature while the washing drum is still at a standstill, after which a reversing process is initiated and the laundry is moistened with the preheated wetting liquid. Then the free liquor in the bottom of the lye tub is heated to the set washing program end temperature.

Another method for wetting laundry in a washing machine is in DE 10 2007 028 212 A1 disclosed. This method comprises steps for supplying an amount of liquid which is less than or equal to an amount required to saturate the wash items with water, for heating the wash items and for supplying a further amount of liquid having a temperature which is less than a temperature of 40 ° ,

Against this background, it was an object of the present invention to provide a method for operating a washing machine in which a washing process can be carried out in the most energy-efficient manner possible. The invention is also based on the object of providing a washing machine which is suitable for carrying out this method.

This object is achieved according to this invention by a method for operating a washing machine and by a washing machine for treating laundry with the features of the corresponding independent claims. Preferred embodiments of the washing machine according to the invention and of the method according to the invention are in corresponding dependent claims and the following description and the accompanying drawings. Preferred embodiments of the washing machine according to the invention correspond to preferred embodiments of the method according to the invention and vice versa, also insofar as this is not explicitly stated here.

The invention thus relates to a method for operating a washing machine for treating laundry with a drum rotatably mounted in a tub, a drive motor for the drum, a control device, a water supply system, a measuring device for determining an amount of aqueous liquid introduced into the tub, a heater for heating the aqueous liquid in the tub and a temperature sensor, the steps
Pouring a first amount q1 of aqueous liquid at a temperature Tq1 into the tub;
Heating the amount q1 of aqueous liquid to a predetermined temperature T1>Tq1;
wherein the quantity q1 can be filled in in one step or in a plurality of subsets q1 'and heating to the temperature T1 can begin after filling in q1 or after adding one or more subsets q1', q1 and a first filled in q1 "each is greater than an amount qmin required to cover the heater;
Adding a second amount of water q2 with a temperature Tq2 <T1 to the heated amount of water q1; and
Carrying out a washing phase with the laundry to be carried out in the presence of a detergent.

Steps (a) to (c) are thus carried out in a wetting phase.

The term "aqueous liquid" means in particular water or wash liquor.

The temperature sensor used here controls the heating in such a way that the temperatures to be set can be set.

The predetermined temperature T1 is not particularly limited. However, T1 is preferably in the range from 30 to 60 ° C.

Furthermore, the quantity q1 is determined as a function of an energy Emax that can be used for the method and the predetermined temperature T1, a relationship between Emax, T1 and q1 being stored in the control device.

The method according to the invention makes it possible to respond flexibly to the requirements of a laundry to be cleaned. It can make sense to heat a quantity of water to be heated in one or more steps.

In a preferred embodiment of the method, the amount q _{1 of} the aqueous liquid is heated to the predetermined temperature T ₁ in one step. If in this case the heated amount q _{1 is} brought into contact with the laundry for wetting, the laundry can be heated relatively quickly. This can be advantageous in view of the reduced time required for a subsequent washing phase. However, at a high predetermined temperature T _{1 there is in} principle the risk that certain impurities, in particular protein-containing soiling, are burned into the laundry.

In the event that partial quantities q ₁ 'are preferably used, depending on an energy _heating that can be used for heating q ₁ in step (b) and which is less than a maximum energy _max that can be used for the method, and the predetermined one Temperature T ₁ defines the subsets q ₁ ', after filling them into the tub, heating takes place, a relationship between _heating , T ₁ and the subsets q ₁ ' being stored in the control _device . It can be heated to the temperature T ₁ after the addition of the subsets q ₁ '. However, less heating can also take place as long as the total amount q ₁ of aqueous liquid is heated to T ₁ in step (b).

In a preferred embodiment of the method according to the invention the washing phase in step (d) provide a total amount q _total = q ₁ + Σ q _n of aqueous liquid used, wherein the q _n in step (c) and (d) added subsets of for performing are aqueous liquid with a respective temperature T _qn <T ₁ , where n ≥ 2. In this case, it is preferred that, in the event that the quotient q ₁ / q _totally falls below a predetermined value x, in the washing phase of step (d) the quantities q _n with n 3 3 are _totally dependent on the quotient q ₁ / q Schedule will be added.

The total amount q ₁ + q ₂ or generally q _total of aqueous liquid is preferably an optimal amount of water, which therefore leads to the highest washing effect with a certain input of energy for heating the aqueous liquid. q _total can be specified or determined while the method according to the invention is being carried out. For example, during the method according to the invention when using a pressure sensor to determine a water level in the tub from the pressure curve with smaller amounts of water before, during and after heating, the optimal amount of water is determined. This is particularly dependent on a load of laundry, which can be determined, for example, by measuring the weight of the laundry.

The heater is generally turned off during step (c).

The time of adding the detergent required for the washing phase is not particularly limited. In general, the detergent is added as early as possible to enable an optimal washing phase. Depending on the composition, it may make sense to either avoid relatively high temperatures or set them as early as possible. Enzymes in a detergent are often sensitive to excessive temperatures. On the other hand, bleaching agents usually require higher temperatures to develop a bleaching effect.

In any case, a method is preferred according to the invention in which the detergent for the washing phase (d) is contained in q ₁ and / or q ₂ .

In addition, it is preferred in the process of the invention that, depending on the ratio q ₁ / q _2, the amount of water q ₂ is chosen such that the temperature of the amount of water q ₁ + q ₂ does not fall below a predetermined minimum value T _wash for the temperature of the aqueous Liquid falls. This takes into account that the heated to T ₁ water quantity q ₁ before the start of the washing phase due to the addition of relatively cold water quantity q cools _second It is then preferably ensured that a minimum temperature T _{wash of} the wash liquor is given for the wash phase.

Temperatures T _q1 and T _q2 are generally in the range of 5 to 18 ° C. The temperatures T _q1 and T _{q2 are} preferably the same and in particular have the temperature of a tap water used.

In a preferred embodiment of the method according to the invention, which is particularly advantageous in the presence of protein-containing soiling of the laundry, the amount of water q ₁ in step (b) is first reduced to a Temperature T _P1 <T ₁ heated and after wetting the laundry and possibly filling the amount of water in the tub to q ₁ , heating the aqueous liquid in the tub to a temperature T _P2 , T _P1 <T _P2 ≤ T ₁ applies.

In this case, the laundry is generally wetted after heating in that the laundry is brought into contact with the aqueous liquid heated to T ₁ on account of a suitable movement program for the drum, which can also have scooping devices for the aqueous liquid. Due to the temperature condition T _P1 <T _P2 ≤ T ₁ , this procedure can be used, for example, to avoid the burning-in of protein-containing contaminants. T _P1 is preferably in the range from 25 to 35 ° C.

In addition, in a particularly gentle embodiment, it is preferred that in step (b) T _P2 <T ₁ and after reaching the temperature T _P2 , the laundry is rewetted with the aqueous liquid while rotating the drum, and then the amount of water q ₁ , if necessary after filling up the amount of aqueous liquid flowing back into the tub to q ₁ , to the temperature T ₁ . Filling the amount of water to q ₁ after wetting the laundry has taken into account the fact that due to the wetting process, water is bound in the laundry which can no longer flow back into the tub.

If it is necessary to fill up the water quantity to q ₁ , this additional water quantity to be used, which is referred to simply as Δq, can be taken into account for the washing phase by reducing the partial quantities to be added in steps (c) and (d), so that the total q _{total is} preferably not exceeded.

In a particularly preferred embodiment of the method, the amounts q ₁ , q ₂ and / or q _{total are determined} as a function of a loading amount of the drum and / or the type of laundry. For this purpose, there is generally a relationship between the quantities q ₁ , q ₂ and / or q _total in the control device of the washing machine as a function of a load quantity of the drum and / or the type of laundry deposited. If the wetting process and the washing phase are matched to laundry items of different sizes, it can be prevented that with very large laundry items no complete wetting takes place, but in comparison with small laundry items the wetting phase takes too long, based on their wetting success. This also improves wetting uniformity.

Here, the load of the drum with laundry can be determined automatically using a suitable determination method or can be set manually by a user of the washing machine. Likewise, the type of laundry can be determined using a suitable determination method, for example an optical method, or can be set manually by a user of the washing machine.

In the method according to the invention, in step (a) and / or (b), in particular in step (b), the drum is preferably rotated at a higher rotational speed than in step (c).

Preferably, in step (a) and / or (b), particularly in step (b), the drum is rotated at an average rotational speed in the range from 40 to 60 revolutions / min and more preferably in the range from 45 to 55 revolutions / min.

Preferably, the drum in step (c) is rotated at an average rotational speed in the range from 25 to 45 revolutions / min and more preferably in the range from 30 to 40 revolutions / min, in particular in the range from 31 to 39 revolutions / min.

Generally, in the washing phase of step (d) the drum is rotated at an average speed of rotation in the range of 40 to 60 revolutions / min and more preferably in the range of 45 to 55 revolutions / min.

1. (a) Einfüllen einer ersten Menge q₁ an wässriger Flüssigkeit mit einer Temperatur T_q1 in den Laugenbehälter;
2. (b) Erhitzen der Menge q₁ an wässriger Flüssigkeit auf eine vorgegebene Temperatur T₁ > T_q1;
   wobei die Menge q₁ in einem Schritt oder auf mehrere Teilmengen q₁' verteilt eingefüllt werden kann und das Erhitzen auf die Temperatur T₁ nach Einfüllen von q₁ oder bereits nach Zugabe von einer oder mehreren Teilmengen q₁' beginnen kann, wobei q₁ und eine erste eingefüllte Teilmenge q₁" jeweils größer einer Menge q_min ist, die zum Bedecken der Heizeinrichtung erforderlich ist;
3. (c) Hinzufügen einer zweiten Wassermenge q₂ mit einer Temperatur T_q2 < T₁ zur erwärmten Wassermenge q₁ ; und
4. (d) Durchführung einer Waschphase mit der Wäsche in Gegenwart eines Waschmittels, wobei in Abhängigkeit von einer für das Verfahren vorgegebenen einsetzbaren Energie E_max und der vorgegebenen Temperatur T₁ die Menge q₁ festgelegt wird, wobei in der Steuereinrichtung ein Zusammenhang zwischen E_max, T₁ und q₁ hinterlegt ist

The invention also relates to a washing machine for treating laundry with a drum rotatably mounted in a tub, a drive motor for the drum, a control device, a water supply system, a measuring device for determining an amount of aqueous liquid introduced into the tub, a heating device for heating the aqueous liquid in the tub and a temperature sensor, the control device being set up to carry out a method with the steps

1. (a) pouring a first amount q ₁ of aqueous liquid with a temperature T _q1 into the tub;
2. (b) heating the amount q ₁ of aqueous liquid to a predetermined temperature T ₁ > T _q1 ;
   wherein the quantity q ₁ can be filled in in one step or in several subsets q ₁ 'and heating to the temperature T ₁ can begin after filling in q ₁ or after adding one or more subsets q ₁ ', where q ₁ and a first filled-in partial quantity q ₁ "is in each case greater than a quantity q _{min which} is required to cover the heating device;
3. (c) adding a second amount of water q ₂ with a temperature T _q2 <T ₁ to the heated amount of water q ₁ ; and
4. (d) Carrying out a washing phase with the laundry in the presence of a detergent, the amount q _{1 being} determined as a function of an energy E _{max that} can be used for the method and the predetermined temperature T ₁ , a relationship between E _max , T ₁ and q _{1 is} deposited

The temperature sensor used here controls the heating in such a way that the temperatures to be set can be set.

The washing machine according to the invention contains a measuring device for determining an amount of aqueous liquid introduced into the tub. A clock, a flow meter and / or a water level sensor are preferably provided as the measuring device. For example, when using a watch, the time can be measured in which water flows in via a water supply system. If the water pressure is known and constant, the amount of aqueous liquid, in particular tap water, introduced into the tub can be estimated well by measuring the time in which a valve is open.

More precise measurement results are made possible by using a flow meter and / or a water level sensor. Because a water level sensor too Taking into account that part of the aqueous liquid has possibly already been absorbed by the laundry, washing machines are preferred according to the invention in which both a flow meter and a water level sensor are present.

The washing machine and method according to the invention have numerous advantages. It is thus possible to carry out a washing process in a more energy-efficient manner by using an already heated aqueous liquid for wetting and preheating the laundry. It is sufficient to use a relatively small amount of the aqueous liquid and in any case not a large amount which is generally necessary for a washing phase. The laundry can be preheated in this way with a relatively warm aqueous liquid, so that even with a later addition of colder water, in embodiments of the invention in one or more separate portions, washing can be carried out with a relatively high washing temperature. Finally, the temperature of the laundry is a decisive factor in the washing phase, since this is where the interaction with a washing liquor takes place. Since, according to the invention, the water used for wetting is heated relatively early, in principle a faster-running washing process can also be implemented.

Overall, due to the small amount of water to be heated, the temperature desired by a user and generally required to ensure the washing effect can be achieved with significantly reduced energy consumption. For detergents without bleach activator, e.g. IEC-B plus perborate as in the Australian or Saudi Arabian standard, a bleaching effect can be achieved with significantly reduced energy input.

In addition, a more uniform absorption of the detergent by the laundry can be supported if the detergent to be used is dissolved with a little very warm water before the laundry is saturated with water.

Finally, a hygiene effect can be achieved if the water heated to T _{1 is} distributed in the laundry before the addition of further, colder water. For this purpose, T ₁ should be as high as possible.

• Fig. 1 zeigt eine nicht einschränkend gemeinte Ausführungsform einer erfindungsgemäßen Waschmaschine, in der ein erfindungsgemäßes Verfahren durchgeführt werden kann.
• Fig. 2 zeigt ein Diagramm mit einem zeitlichen Überblick über den Ablauf eines Waschverfahrens nach dem Stand der Technik.
• Fig. 3 zeigt ein Diagramm mit einem zeitlichen Überblick über den Ablauf eines Waschverfahrens gemäß der vorliegenden Erfindung.

The invention is described below with reference to the Figures 1 to 3 explained in more detail.

• Fig. 1 shows a non-limiting embodiment of a washing machine according to the invention, in which a method according to the invention can be carried out.
• Fig. 2 shows a diagram with a temporal overview of the course of a washing process according to the prior art.
• Fig. 3 shows a diagram with a temporal overview of the course of a washing process according to the present invention.

Fig. 1 shows a non-limiting embodiment of a washing machine according to the invention, in which a method according to the invention can be carried out.

The washing machine contains a tub 1, in which a laundry drum 2 is rotatably mounted about a horizontal axis 3 and can be driven by a drive motor 14. By means of laundry carriers 4 and scooping devices 5 for the washing liquor 6, an intensive flooding of the laundry 7 with washing liquor 6 and a reduction in the free liquor not bound in the laundry 7 is achieved in particular in the direction of rotation of the arrow 16. The washing machine also has an alkali inlet system, which comprises a water connection fitting for the domestic water network 8, an electrically controllable valve 9 and a feed line 10 to the suds container 1, which is guided here via a detergent dispenser or dish 11, from which the incoming water detergent portions in the Tub 1 can transport. The valve 9 can be controlled by a control device 12 as a function of a program flow chart, which can be linked to a time program and / or to the achievement of certain measured values of parameters (lye level, temperature of the lye, speed of the laundry drum, etc.) within the washing machine , There is also a heating device 13 in the tub 1, which can also be switched by the control device 12. Finally, a temperature sensor 17 for measuring the temperature of the aqueous liquid 6 and a water level sensor 15, for example a pressure sensor, for measuring the amount of aqueous liquid 6 in the tub 1 are also present in the washing machine. In the embodiment shown here, a flow rate meter 18 is also present in the feed line 10.

A washing program in this washing machine generally begins with the opening of valve 9 in order to lead water from the domestic water network 8 into the tub 1. A watch, not shown here, can be used to determine a quantity of water filled in over the time required for this.

1. (a) Einfüllen einer ersten Menge q₁ an wässriger Flüssigkeit 6 mit einer Temperatur T_q1 in den Laugenbehälter 1;
2. (b) Erhitzen der Menge q₁ an wässriger Flüssigkeit 6 auf eine vorgegebene Temperatur T₁ > T_q1;
3. (c) Hinzufügen einer zweiten Wassermenge q₂ mit einer Temperatur T_q2 < T₁ zur erwärmten Wassermenge q₁; und
4. (d) Durchführung einer Waschphase mit der Wäsche 7 in Gegenwart eines Waschmittels

durchgeführt.When carrying out the method according to the invention in this washing machine, the steps are

1. (a) filling a first quantity q ₁ of aqueous liquid 6 with a temperature T _q1 into the tub 1;
2. (b) heating the amount q ₁ of aqueous liquid 6 to a predetermined temperature T ₁ > T _q1 ;
3. (c) adding a second amount of water q ₂ with a temperature T _q2 <T ₁ to the heated amount of water q ₁ ; and
4. (d) Carrying out a washing phase with the laundry 7 in the presence of a detergent

carried out.

The quantity q ₁ can be filled in in one step or in several subsets q ₁ 'and the heating to the temperature T ₁ , monitored by means of the temperature sensor 17, can be carried out after filling in q ₁ or after adding one or more subsets q ₁ ' begin, with q ₁ and a first partial quantity q ₁ "each being greater than a quantity q _{min which} is required to cover the heating device 13. This ensures that the heating device 13 does not run dry and must be switched off by a safety device which is generally present ,

19 means the water level for a quantity q ₁ which is sufficient for immersing the laundry 7. 20 means the water level at a quantity q ₁ at which the drum 2 is just touched by the aqueous liquid 6. 21 is the minimum quantity q _min required to cover the heating device 13. 22 is the base of the tub.

Fig. 2 schematically shows the temperature profile 23 and the water level profile 24 of an aqueous liquid in a tub during a conventional washing process for a conventional method. t means time. With the conventional The method is filled in step (A) without heating water up to a maximum height H _max . Subsequently, in step (B), when the water supply is interrupted, laundry is wetted so that the water level drops again. After the wetting, the aqueous liquid is then heated in step (C) to the temperature T _max , which is the starting temperature for the washing phase (D). As the washing phase (D) stops heating, the temperature drops slightly here.

Fig. 3 schematically shows the temperature profile 25 and the water level profile 26 of an aqueous liquid in a tub for an inventive method during a washing process according to the invention. t means time. In the method according to the invention, a relatively small amount q _{1 of} an aqueous liquid is first introduced without heating in step (a). An aqueous liquid can in particular already contain a detergent. This amount q ₁ is then heated up to T ₁ in step (b). Depending on the extent to which there is contact with laundry, the water level 26 can drop more or less. In step (c) a further addition of aqueous liquid then takes place with the heating switched off, until in this embodiment the total amount of aqueous liquid to be used for the washing phase (d) is available. The temperature in the tub drops slightly.

LIST OF REFERENCE NUMBERS

1

tub

2

Drum, laundry drum

3

axis of rotation

4

laundry agitator

5

scooping devices

6

Suds; water

7

Laundry

8th

Domestic water supply

9

Valve

10

supply

11

dispenser tray

12

control device

13

heater

14

drive motor

15

Water level sensor

16

Arrow for the direction of rotation of the drum; scooping direction

17

temperature sensor

18

Device for determining an amount of aqueous liquid introduced into the tub; Flow Meter

19

Water levels of q ₁ sufficient to immerse the laundry

20

Water level at a quantity q ₁ at which the drum is just touched by the aqueous liquid

21

minimum quantity q _min

22

Tub floor

23

Temperature curve in the conventional process

24

Water level curve in the conventional process

25

Temperature profile in the method according to the invention

26

Course of water level in the method according to the invention

Claims (13)

1. Method for operating a washing machine for treating laundry (7), having a drum (2) mounted in a rotatable manner in a tub (1), having a drive motor (14) for the drum (2), having a control device (12), having a water-supply system (8, 9, 10, 11), having a measuring device (15, 18) for determining a quantity of aqueous liquid (6) introduced into the tub (1), having a heating device (13) for heating the aqueous liquid (6) in the tub (1), and having a temperature sensor (17), which serves for regulating the heating device (13) in such a manner that the temperatures to be set can be set, wherein in the method the following steps are carried out:

   (a) introducing a first quantity q₁ of aqueous liquid (6) at a temperature T_q1 into the tub (1);

   (b) heating the quantity q₁ of aqueous liquid (6) to a predetermined temperature T₁ > T_q1;
   wherein the quantity q₁ can be introduced in one step or in a state in which it is divided into a plurality of sub-quantities q₁', and heating to the temperature T₁ can begin following the introduction of q₁ or after one or more sub-quantities q₁' have been added, wherein q₁ and a first sub-quantity q₁" introduced are each greater than a quantity q_min, which is necessary for covering the heating device (13);

   (c) adding a second aqueous quantity q₂ at a temperature T_q2 < T₁ to the heated aqueous quantity q₁; and

   (d) carrying out a washing phase with the laundry (7) in the presence of a detergent, wherein the quantity q₁ is determined as a function of a maximum predetermined energy E_max which can be used for the method and the predetermined temperature T₁, wherein a connection between E_Max, T₁ and q₁ is stored in the control device (12).
2. Method according to claim 1, characterised in that the quantity q₁ of aqueous liquid (6) is heated in one step to the predetermined temperature T₁.
3. Method according to claim 1, characterised in that the sub-quantities q₁', after whose introduction into the tub (1) heating occurs in each case, are determined as a function of an energy E_heating which can be used for heating q₁ in step (b), which amount of energy is lower than a maximum energy E_max which can be used for the method, and the predetermined temperature T₁, wherein a connection between E_heating, T₁ and the sub-quantities q₁' is stored in the control device (12).
4. Method according to one of claims 1 to 3, characterised in that a total quantity q_total = q₁ + ∑ q_n of aqueous liquid is used for carrying out the washing phase in step (d), wherein the q_n are sub-quantities of aqueous liquid (6) added in step (c) and step (d) at a respective temperature T_qn < T₁, wherein n ≥ 2.
5. Method according to claim 4, characterised in that for the event that the quotient q₁/q_total falls below a predetermined value x, the quantities q_n, where n ≥ 3, are added in the washing phase of step (d) according to a timetable dependent on the quotient q₁/q_total.
6. Method according to one of claims 1 to 5, characterised in that the detergent for the washing phase (d) is contained in q₁ and/or q₂.
7. Method according to one of claims 1 to 6, characterised in that the quantity of water q₂ is chosen as a function of the ratio q₁/q₂ such that the temperature of the quantity of water q₁ + q₂ does not drop below a predetermined minimum value T_wash for the temperature of the aqueous liquid (6).
8. Method according to one of claims 1 to 7, characterised in that the quantity of water q₁ in step (b) is firstly heated to a temperature T_P1 < T₁ and after a wetting of the laundry (7) and an optionally necessary topping-up of the quantity of water in the tub (1) to q₁, the aqueous liquid (6) in the tub (1) is heated to a temperature T_P2, where T_P1 < T_P2 ≤ T₁.
9. Method according to claim 8, characterised in that T_P1 is in the range of 25 to 35°C.
10. Method according to claim 8 or 9, characterised in that in step (b) Tp₂ < T₁ and after reaching the temperature T_P2 with rotation of the drum (2) the laundry (7) is rewetted with the aqueous liquid (6) and then the quantity of water q₁, optionally after topping-up the quantity flowing back into the tub (1) with aqueous liquid (6) to q₁, is heated to the temperature T₁.
11. Method according to one of claims 1 to 10, characterised in that the quantities q₁, q₂ and/or q_total are determined as a function of a load size of the drum (2) and/or the type of laundry (7).
12. Washing machine for treating laundry (7), having a drum (2) mounted in a rotatable manner in a tub (1), having a drive motor (14) for the drum (2), having a control device (12), having a water-supply system (8, 9, 10, 11), having a measuring device (15, 18) for determining a quantity of aqueous liquid (6) introduced into the tub (1), having a heating device (13) for heating the aqueous liquid (6) in the tub (1), and having a temperature sensor (17), which serves for regulating the heating device (13) in such a manner that the temperatures to be set can be set, characterised in that the control device (12) is set up to carry out a method having the following steps:

    (a) introducing a first quantity q₁ of aqueous liquid (6) at a temperature T_q1 into the tub (1);

    (b) heating the quantity q₁ of aqueous liquid (6) to a predetermined temperature T₁ > T_q1;
    wherein the quantity q₁ can be introduced in one step or in a state in which it is divided into a plurality of sub-quantities q_1', and heating to the temperature T₁ can begin following the introduction of q₁ or after one or more sub-quantities q₁' have been added, wherein q₁ and a first sub-quantity q₁" introduced are each greater than a quantity q_min, which is necessary for covering the heating device (13);

    (c) adding a second quantity of water q₂ at a temperature T_q2 < T₁ to the heated quantity of water q₁; and

    (d) carrying out a washing phase with the laundry (7) in the presence of a detergent, wherein the quantity q₁ is determined as a function of a maximum predetermined energy E_max which can be used for the method and the predetermined temperature T₁, wherein a connection between E_Max, T₁ and q₁ is stored in the control device (12)..
13. Washing machine according to claim 12, characterised in that a clock, a flow meter (18) and/or a water level sensor (15) is/are present as a measuring device (15, 18).

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