EP3000924B1 - Method for operating a washing and drying machine with protection against thermal shock and clothes dryer suitable for said method - Google Patents

Description

The invention relates to a method for operating a washer dryer with protection against thermal shock and a suitable washer-dryer. More particularly, the invention relates to a method of operating a washer dryer, wherein the washer dryer comprises a tub; a rotatably mounted in the tub drum with a closable glass door, the drum is used for receiving and removal of laundry with the glass door open; a control device and a process air duct in which a heater for heating air, a blower, and at least one temperature sensor for measuring a temperature T _pc are. The invention also relates to such a washer-dryer.

Washer dryers are popular because they combine the functions of a washing machine and a tumble dryer in a single device in a space-saving manner. In addition, a washer-dryer is already provided with a water connection, so that water is not only available for washing laundry, but also for further treatment of laundry items.

When operating a washer dryer, however, very different temperatures can occur. In particular, when drying and washing processes follow each other rapidly, it can lead to burdens for the components and materials used in the washer-dryer due to the abrupt temperature changes taking place. This is particularly problematic when the temperature in the washer-dryer changes very much within a short period of time, in particular when cooled by cold tap water, if a drying program had previously been carried out. A sufficient thermal shock resistance is therefore important for washer-dryer. This is especially true for the glass door (also referred to as "access door") of a washer dryer, are introduced through the laundry items to be treated in the drum of the clothes dryer. When operating a washer dryer, therefore, a maximum thermal shock resistance is to be observed. Here, the "thermal shock resistance" is the maximum possible temperature difference, when used as a thermal shock, there is no bursting of the glass.

Recently, the increase of the drying temperature in a dryer and in a washer-dryer is considered in order to be able to carry out drying processes with wet laundry even more quickly.

However, the soda-lime glass generally used for corresponding access doors can no longer be used if it is to be possible that there is a rapid transition between a high temperature process air drying process and a cold water washing process and the temperature difference is 100 Kelvin or more. This can be remedied by the use of borosilicate glass. This is expensive.

High surface temperatures in a washer dryer can also pose a danger to a user. In order to ensure the surface temperature of the washer-dryer allowed in view of the protection of a user of the washer-dryer, the user's operation of the washer-dryer, i. in the closed state of the access door, facing outside of the door glass often protected by an additional disc of glass or plastic. As a result, in addition to protection against too high a surface temperature, in particular protection against cold shock caused by cold water, if possibly cold water would reach the outside of the access door.

However, in particular, a temperature shock can be caused by cold water that reaches the inside of the glass door. This is e.g. the case when a washing program is started by introducing cold water immediately after or during a drying process. Then cold water can be injected from the inside against the glass door or be transported through the laundry items from the bottom of the tub to the glass door.

The EP 2 636 788 A1 describes a clothes dryer comprising: a drum moving laundry items, a window glass openably disposed in front of the drum; a blower unit which sends dry air; a dehumidifying unit which dehumidifies the drying air discharged from the drum; a heating unit which heats the dehumidified drying air; a first air passage with a first air outlet, which is opened at a rear end of the drum to blow the drying air into the drum; a second air passage having a second air outlet opened in front of the drum for blowing the drying air into the drum; an air passage switching unit that selectively switches between the first and second air passages; a temperature detecting unit which detects a temperature of the window glass; and a control unit, wherein the control unit performs control such that switching is selectively performed between the first air passage and the second air passage by the air passage switching unit when the detection result of the temperature detecting unit reaches a first predetermined temperature. This is to ensure that items of laundry in the drum are not dried inconsistently. In preferred embodiments, the drying air is blown toward the window glass.

The EP 2 636 788 A1 also states that after a drying process, the high temperature glass door must be cooled before the dried laundry can be removed from the dryer. For this purpose, it is known to carry out a cooling process in order to cool a window glass. To EP 2 636 788 A1 For example, it is possible to operate the laundry dryer in which laundry items may be dried while at the same time controlling the temperature of the window glass so as to maintain a predetermined temperature at which the glass is not too hot for a user.

The CN 1521313 A describes a washer-dryer with a guide tube which guides the hot process air so that it does not come into direct contact with the glass door of the washer-dryer. This is to prevent damage to the glass door due to abrupt temperature changes and scalding a user of the washer dryer.

The DE 10 2012 207 742 A1 describes a method for operating a dryer with a program control, a drum for laundry to be dried, a process air duct in which a process air blower for conveying the process air and a heater for heating the process air, and with a variable speed drive motor, the drum and the process air blower drives, wherein the method comprises a heating phase, a quasi-stationary drying phase and a cooling phase, wherein in the quasi-stationary drying phase of the variable-speed drive motor is operated at a mean speed α ₁ and the process air blower with a mean speed ω ₁ , and during the cooling phase at least temporarily the variable-speed drive motor with a speed α _{2 is} less than α ₁ and the process air fan is operated at a speed ω ₁ . Preferably, the method is operated so that a maximum allowable temperature T _{max of} the process air is not exceeded.

The US 2006/0137105 A1 describes a drying control method in a washer-dryer in which air is circulated in a drum so that the air passes successively through a tub, a condensation tube and a heating tube and in turn is fed inside the drum and dries laundry in the drum, comprising: Providing cooling water in the condensation tube for the condensation of moisture contained in the circulating air; Measuring a temperature of the cooling water dripping from the condensation tube into the tub or a temperature of the circulating air; and removing the cooling water from the tub to the outside when the temperature is higher than a predetermined temperature. In one embodiment, the heater is on (see Fig. 10, step S11).

The US 2013/0219741 A1 describes a washer-dryer with a housing; a tub attached to the housing; a drum rotatably mounted in the tub; a drying channel that heats air coming out of the tub to a predetermined temperature to return the heated air to the tub; an air-cooled condensing unit condensing moisture on at least a predetermined area of an inner peripheral surface of the tub; and a detection unit for detecting the amount of condensate generated in the tub. Described is in particular a drying process in which the applied drying temperature should not be too high, so that the heating is controlled accordingly. In addition, a method is provided by which the time of completion of the drying is determined by detecting a surface temperature of a tub during drying of laundry, and a corresponding drying method.

Against this background, the object of the invention was to provide a method for operating a washer-dryer with improved protection against temperature shocks. Preferably, a protection of a glass door of the washer dryer from damage due to a high temperature shock should be achieved. The task was also to show a suitable washer-dryer.

The object underlying the invention is achieved by a method and a washer-dryer according to respective independent claim. Preferred embodiments of the invention are listed in the respective dependent claims. Preferred embodiments of the method according to the invention correspond to preferred embodiments of the washer-dryer according to the invention, even if it is not separately pointed out here in each case.

1. (a) Messen einer Temperatur T_pc ¹ im Prozessluftkanal mit dem mindestens einen Temperatursensor, beispielsweise den Temperatursensoren T1,T2 und/oder T3;
2. (b) bei abgeschalteter Heizung Durchführen eines Abkühlungsprogramms mit der Prozessluft für den Fall, dass T_pc ¹ ≥ T_pc ^lim ist, worin T_pc ^lim eine obere Grenztemperatur ist, und wobei das Abkühlungsprogramm solange durchgeführt wird, bis eine vorgegebene Temperatur T_pc ^set ≤ T_pc ^lim erreicht ist, so dass das Abkühlungsprogramm eine. Abkühlung der Prozessluft und dadurch der Glastür erreicht, wobei das Abkühlungsprogramm das Kontaktieren der warmen Prozessluft mit Wasser aus einem Wasserzuleitungssystem umfasst, wobei die Temperatur T_pc ^lim in Abhängigkeit von einer Temperatur T_aq des Wassers aus dem Wasserzuleitungssystem so festgelegt wird, dass eine vorgegebene Temperaturschockfestigkeit ΔT_shock nicht überschritten wird; und
3. (c) Durchführen eines Waschprogramms.

The invention thus relates to a method for operating a washer dryer, wherein the washer dryer a tub, a tub rotatably mounted in the tub with a closable glass door, wherein the drum for receiving and removal of laundry with the glass door open, a control device and a process air duct, in which comprises a heater for heating air, a fan and at least one temperature sensor for measuring a temperature T _pc , comprising the steps:

1. (A) measuring a temperature T _pc ¹ in the process air duct with the at least one temperature sensor, for example the temperature sensors T1, T2 and / or T3;
2. (b) with the heating off, performing a cooling program on the process air in the case where T _pc ¹ ≥ T _pc ^lim , where T _pc ^{lim is} an upper limit temperature, and wherein the cooling program is performed until a predetermined temperature T _pc ^set ≤ T _pc ^{lim is} reached, so that the cooling program a. Cooling of the process air and thereby reaches the glass door, wherein the cooling program comprises contacting the warm process air with water from a water supply system, wherein the temperature T _pc ^lim depending on a temperature T _{aq of} the water from the water supply system is set so that a predetermined thermal shock resistance ΔT _{shock is} not exceeded; and
3. (c) performing a washing program.

Preferably, in step (b), the cooling program is performed when T _pc ¹ > T _pc ^lim .

If the temperature sensor is located directly on the glass door or in its immediate vicinity, then it can directly measure the temperature of the glass door. However, it is also possible to use a temperature sensor that is significantly removed from the glass door. In such a case, before the measurement, the blower of the process air for a certain period .DELTA.t _blow can be turned on to effect a temperature compensation along the process air duct and thus to ensure that the temperature sensor provides a signal significant for the temperature of the glass door. The period .DELTA.t _blow may not exceed a length of one minute and in particular be about 30 seconds.

If the temperature of the glass door is measured with a temperature sensor T3 attached directly to it, an immediately suitable measured variable is available at any time in order to decide whether an additional cooling step has to be carried out. If the corresponding temperature sensor T1 or T2 is not located directly on the glass door, the temperature of the glass door can be determined indirectly by operating the process air blower for a short period of time, which in particular lasts less than one minute, preferably for about 30 seconds before the detection of a measured value becomes. This advantageously achieves a uniform temperature distribution in the process air duct so that the temperatures of the process air measured by the temperature sensors, for example T1 or T2, can be used as a representative measure of the temperature of the glass door.

The upper limit temperature T _pc ^lim is to be selected as a function of the shock temperature ΔT _shock corresponding to the material of the glass door. In particular, one starts from the lowest expected water inlet temperature, ie a fresh water temperature Tw-min expected in a cold season in a public water supply network. This temperature T _W-min can be set at 3 ° C, for example, in Central Europe. Then T _pc ^lim = T _W-min + ΔT _{shock can be} set. As an alternative, it is also possible to determine the temperature of the fresh water T _aq available in the concrete individual case by means of a correspondingly provided temperature sensor and the upper limit temperature then relevant for this individual case T _pc ^lim = T _aq + ΔT _shock set.

A method is preferred in which the cooling program comprises a passage of process air through a heat exchanger arranged in the washer-dryer.

The cooling program aims to efficiently cool the process air and thereby the glass door. That is, in the method according to the invention in particular when reaching or exceeding the temperature T _pc ^lim the process air is cooled. By applying the cooled process air then a cooling of the glass door can be achieved. Thus, according to the invention, in general, no cooling of the glass door is achieved in that the guidance of the process air in one or more process air ducts as in the EP 2 636 788 A1 is changed described. In particular, process air according to the invention is not cooled by contact with laundry in order to use such a cooled process air for cooling a glass door. The nature and design of the cooling program will generally depend on which means are available for cooling process air in the washer-dryer. In addition, the type and design of the cooling program will generally depend on the way the water intended for washing from a water supply system enters the tub, in particular, whether the water can get in contact with the glass door in this way.

In the event that a condensate tray or a condensate container are present in the tumble dryer, the condensate contained therein can additionally be used to cool excess process air by bringing the hot process air into contact with the condensate so that heat is exchanged. This can be further promoted by evaporation of condensate and therefore the withdrawal of heat of vaporization.

In a preferred embodiment, the cooling program comprises contacting the warm process air with water from a flushing device for a heat exchanger in the washer-dryer.

According to the invention, the cooling program for the process air comprises contacting the warm process air with water from a water supply system.

In the last two cooling programs, it is preferred that the amount of water used in the cooling program M _c flows into the tub and is chosen so that it is smaller than the amount of water M _b in the tub, which is necessary so that a lower end the drum dips into the water.

However, cooling programs using water as a coolant are particularly advantageous in that the water entering the tub and drum is heated, thereby reducing the risk of excessive temperature shocks.

Moreover, it is preferred that the water heated by the warm process air from the flushing device and / or the water supply system is used for the execution of the washing program in step (c).

According to the invention, a method is preferred in which the temperature T _pc ^{lim is set} as a function of a temperature T _{aq of} the water in a water supply system such that a predetermined thermal _shock resistance ΔT _{shock is} not exceeded. For this purpose, a relationship between the temperature T _pc ^lim and the temperature T _aq is generally stored in the control unit of the washer-dryer.

The thermal _shock resistance ΔT _shock depends on the composition of the glass material and the production process of the glass door. For commonly used soda lime glass, it is typically 100 Kelvin. The thermal shock resistance of a glass door is tested by immersing the glass door, heated to a temperature T _x, in water at a temperature T _y , for example in a water bath at a temperature of 20 ° C. If there is no damage to the glass door, the thermal shock resistance is at least ΔT _xy = T _x -T _y .

The temperature T _{aq of} the water from a water supply system can be adjusted by a user of the washer dryer or measured via a arranged in the water supply system temperature sensor and fed to the control unit.

In the method according to the invention, during the cooling program the drum is preferably rotated, e.g. at a speed in the range of 40 to 60 revolutions / min, in particular if it contains laundry items. The drum is preferably operated in reversing mode.

The wash program in step (c) generally begins by passing water from the water supply system into the drum and tub. Before step (c), generally the rotation of the drum and / or the fan are switched off. The addition of water from the water supply system generally also causes cooling. In contrast, the cooling program of step (b) is generally already finished.

1. (a) Messen einer Temperatur T_pc ¹ im Prozessluftkanal mit dem mindestens einen Temperatursensor;
2. (b) bei abgeschalteter Heizung Durchführen eines Abkühlungsprogramms mit der Prozessluft für den Fall, dass T_pc ¹ ≥ T_pc ^lim ist, insbesondere T_pc ¹ > T_pc ^lim ist, worin T_pc ^lim eine obere Grenztemperatur der Prozessluft ist, wobei das Abkühlungsprogramm solange durchgeführt wird, bis eine vorgegebene Temperatur T_pc ^set ≤ T_pc ^lim erreicht ist, so dass das Abkühlungsprogramm eine Abkühlung der Prozessluft und dadurch der Glastür erreicht, wobei das Abkühlungsprogramm das Kontaktieren der warmen Prozessluft mit Wasser aus einem Wasserzuleitungssystem umfasst, wobei die Temperatur T_pc ^lim in Abhängigkeit von einer Temperatur T_aq des Wassers aus dem Wasserzuleitungssystem so festgelegt wird, dass eine vorgegebene Temperaturschockfestigkeit ΔT_shock nicht überschritten wird; und
3. (c) Durchführen eines Waschprogramms.

The invention also relates to a laundry dryer, comprising a tub, a tub rotatably mounted in the tub with a closable glass door, wherein the drum for receiving and removal of laundry with the glass door open, a control device and a process air duct, in which a heater for heating air, a blower, and at least one temperature sensor for measuring a temperature T _pc , the control device being set up to carry out a method comprising the steps:

1. (A) measuring a temperature T _pc ¹ in the process air duct with the at least one temperature sensor;
2. (b) with the heating off, performing a cooling program on the process air in the event that T _pc ¹ ≥ T _pc ^lim , in particular T _pc ¹ > T _pc ^lim , where T _pc ^{lim is} an upper limit temperature of the process air, the cooling program is carried out until a predetermined temperature T _pc ^set ≤ T _pc ^{lim is} reached, so that the cooling program reaches a cooling of the process air and thereby the glass door, wherein the cooling program comprises contacting the warm process air with water from a water supply system, wherein the temperature T _pc ^{lim is set} as a function of a temperature T _{aq of} the water from the water supply system so that a predetermined thermal _shock resistance .DELTA.T _{shock is} not exceeded; and
3. (c) performing a washing program.

The specific properties and advantages of this washer dryer can be understood, inter alia, from the above statements on the method according to the invention, to which reference is accordingly made.

In a preferred embodiment, a temperature sensor T1 at a drum inlet, where process air enters the drum, a temperature sensor T2 at a drum outlet, where process air exits the drum, and / or a temperature sensor T3 are arranged directly on the glass door for measuring the temperature T _pc ,

The temperatures measured by the temperature sensors T1, T2 and / or T3 may be the same or different when using a plurality of temperature sensors. The measured temperatures are preferably used as a measure of the temperature of the glass door, where appropriate, they must be converted in a predetermined manner based on empirical values or simulations. When using a plurality of temperature sensors T1, T2 and / or T3, for example, their mean value is taken as a measure of the temperature of the glass door. However, it is also advantageous to carry out this mean value while weighting the values obtained by the individual temperature sensors, wherein the weighting of the value of a temperature sensor, in particular with the proximity of this temperature sensor to the glass door, increases.

The washer-dryer according to the invention is preferably equipped with a heat exchanger which is used for dehumidifying moist, warm process air from the drum. If present, this heat exchanger is particularly suitable for carrying out a cooling program according to step (b) of the method according to the invention.

In general, in a washer-dryer in which the moisture contained in the moist warm air is condensed on a heat exchanger, the heat exchanger is operated with cooling air, cooling water, or when using a heat pump with a refrigerant of the heat pump. The design and efficiency of a cooling program will depend on it.

If a heat exchanger is present in the washer-dryer, preferably one is also available Flushing device for the heat exchanger present, which cleans the heat exchanger of adhering lint and other impurities. This can be connected to the water supply system. When using a flushing device, the water used therein can also be used to cool the process air. The cooled process air conveyed in the process air duct can then cause the glass door to cool down.

The rinsing water of the flushing device used as cooling water generally flows downwards through its outer wall surfaces, which are normally in contact with the process air, where the process air duct is generally connected to the tub via a transition piece.

As used herein, "heating" refers to the air heating (process air) heater located in the process air duct. In addition, a washer-dryer generally also has a heater for direct heating of an aqueous liquid, such as a water heater. a wash. This heating, referred to herein as water heating, is generally located in the tub below the drum. The heating is switched off when carrying out the method according to the invention in step (b).

Moreover, the washer-dryer can be equipped with a condensate collecting device, so that as an aqueous liquid for the Abkühlungsprogramm also incurred in the drying of laundry items condensate can be used.

In general, a washer-dryer has a water supply system with which water can be passed through a generally existing dispenser tray from which detergent or laundry adjuvant portions can be added to the washer-dryer.

A washer-dryer generally has a lye drainage system arranged at the bottom of the lye container with a drain pump as well as generally laundry hoppers and / or scooping devices. Preferably, a washer-dryer in the tub also contains a pressure sensor, which is preferably arranged in a lower region of the tub, so that the pressure of an aqueous liquid present in the tub can be measured.

The invention has numerous advantages. The washer-dryer according to the invention enables the operation of a washer-dryer at comparatively high drying temperatures. The maximum drying temperature in embodiments is up to 120 ° C or even 150 ° C. In addition, it is possible to use for the access door of the washer-dryer a glass having a comparatively low thermal shock resistance, e.g. a soda lime glass with a thermal shock resistance of less than 100 ° C. Such a glass is generally also cheaper than a glass having a relatively high thermal shock resistance, e.g. a borosilicate glass. In this case, a conventional washer-dryer can be used without any special conversion measures being necessary as long as the control device of the washer-dryer is set up to carry out the method according to the invention. In embodiments of the invention, moreover, a preheating of the water used in the washing program can be achieved, so that the energy efficiency increases. Finally, an additional cost-saving effect results from the fact that unified glass doors can be used in a mixed production of washing dryers and washing machines.

The invention will be further elucidated below with reference to the exemplary washer-dryer shown in the single figure of the attached drawing. Other embodiments than the illustrated embodiment are conceivable.

The washer-dryer shown in the single figure has a tub 1 and a drum 2 rotatably mounted therein about a substantially horizontal axis, in which laundry items 3 are located. The tub 1 is connected via a Laugenablaufleitung 19 with a drain pump 12, which can dispose of an aqueous liquid 11 from the tub 1 via a sewer 13 to the outside of the washer dryer. The drum 2 is driven by means of an electric drive motor 4.

The drum 2 is loaded by a glass door 22 with laundry items 3 to be treated. The glass door 22 may have on its outside facing a user in the closed state, a second pane of glass or a plastic, not shown here. In order to be able to wash laundry items 3 in the washer-dryer, the washer-dryer is connected to a water supply system 20 with an external, not shown here Connected to water supply. The water supply system 20 is connected to a dispensing bowl 21, from which with the aid of water from the water supply system 20 detergent or Waschhilfsmittelportionen can be transported into the tub 1. In the present case, this takes place via a part of a process air channel 5 and a sleeve 23.

The arrows 17 indicate the flow direction of the process air in the process air duct. 28 means a drum input and 24 a drum output. 9 means a valve.

For drying wet laundry in the drum 2, in the washer-dryer of the figure, which operates on the recirculation principle, the air heated by a heater 7 ("process air") is conveyed through a fan 6 in a process air duct 5. In this case, heated process air passes through the sleeve 23 through the drum inlet 28 into the tub 1 and the drum 2. After passing through the drum 2 and drying in this wet laundry 3 passes the then humid process air through a rear exit 24 from the tub 1 to a heat exchanger 8, where the moisture contained in it condense due to the cooling of the process air and can be collected in a condensate tank, not shown here. Alternatively, the condensate flow through a transition piece 25 between the heat exchanger 8 and 1 lye tank back into the tub 1, from where it can be disposed of via the lye drain line 19 with the drain pump 12 via the sewer 13 to the outside of the washer dryer. The dehumidified process air then continues to flow in the process air channel 5 and can be heated again by means of the heater 7 and pass through the sleeve 23 into the drum 2, etc.

The washer-dryer of the embodiment shown in the figure has three temperature sensors T1 14, T2 15 and T3 16 in the process air duct in order to control the drying process by means of measurements of temperatures in the flowing process air. In addition, the temperature of the glass door 22 can be determined or estimated via a respective temperature measurement taking place there.

A fourth temperature sensor T4 27 is attached to the water supply system 20 to measure a temperature T _aq of the water used in the washer-dryer. The value T _aq is then supplied to the control device 18 of the washer-dryer in order an embodiment of the method to be considered.

1. (a) Messen einer Temperatur T_pc ¹ der Prozessluft im Prozessluftkanal 5 bei der hier gezeigten Ausführungsform mit den Temperatursensoren T1, T2 und T3 14, 15, 16 sowie mit dem Temperatursensor T4 der Temperatur des verwendeten Wassers aus dem Wasserzuleitungssystem 20;
2. (b) Durchführen eines Abkühlungsprogramms mit der Prozessluft für den Fall, dass T_pc ¹ ≥ T_pc ^lim ist, worin T_pc ^lim eine obere Grenztemperatur der Prozessluft ist, wobei das Abkühlungsprogramm solange durchgeführt wird, bis eine vorgegebene Temperatur T_pc ^set ≤ T_pc ^lim erreicht ist; und
3. (c) Durchführen eines Waschprogramms.

In the washer-dryer of the figure, a method according to the invention is carried out, wherein in particular the following steps are carried out:

1. (A) measuring a temperature T _pc ^{1 of} the process air in the process air duct 5 in the embodiment shown here with the temperature sensors T1, T2 and T3 14, 15, 16 and with the temperature sensor T4 the temperature of the water used from the water supply system 20;
2. (B) performing a cooling program with the process air in the event that T _pc ¹ ≥ T _pc ^lim , where T _pc ^{lim is} an upper limit temperature of the process air, wherein the cooling program is performed until a predetermined temperature T _pc ^set ≤ T _pc ^{lim is} reached; and
3. (c) performing a washing program.

For measuring the temperature T _{pc of} the process air, a temperature sensor T1 14 is arranged between a drum inlet 28 and the glass door 22, a temperature sensor T2 15 between the drum outlet 24 and the glass door 22 and a temperature sensor T3 16 on the glass door 22. In the present case, the temperature sensor T3 on the glass door 22 is sufficient. In the embodiment of a washer dryer shown in the figure, the various temperature sensors are used to illustrate various possible arrangements for the temperature sensor (s) and to implement redundant measurement of the temperature T _{pc of} the process air. The latter can contribute to the protection against a failure of a temperature sensor. It is particularly favorable here that already existing sensors are used to develop additional benefits by measuring the temperature of the glass door 22.

In the embodiment of a washer-dryer shown in the figure, the cooling program comprises a passage of process air through the heat exchanger 8, to which a flushing device 10 is assigned. The flushing device 10 is connected via a water valve 9 with a water supply of the washer dryer not shown here. Accordingly, here the cooling program comprises contacting the warm process air with water from the flushing device 10 for the heat exchanger 8. The amount of water used in the cooling program M _c 11 flows into the tub 1 and is chosen so that it is smaller than the amount M _b of water in the tub 1, the is necessary so that a lower end of the drum 2 is immersed in the water. The water 11 passes through a transition piece 25 and a rear exit 24 into the tub 1. The washer dryer of the figure thus has the advantage that the heated by the warm process air water 11 from the flushing device 10 for the implementation of the wash program in step (d ) can be used.

The measurement of the temperature T _{aq of} the water from the water supply system 20 by means of the temperature sensor T4 27 allows the temperature T _pc ^lim depending on a temperature T _{aq of} the water from the water supply system 20 can be set so that a predetermined here thermal _shock resistance .DELTA.T _shock is not exceeded, for example, about 100 Kelvin. During the cooling program, the laundry 2 containing drum 2 is rotated and operated in particular in a Reversierrhythmus, in particular with a rotational speed of 50 revolutions / min. In the process, and as a result, the items of laundry that are located in the drum 2 and possibly come into contact with the glass door 22 are also cooled.

Before carrying out the process, laundry items 3 had generally been dried in the washer-dryer by passing hot process air through the moist laundry items 3 when the heater 7 was switched on by means of the blower 6. When the cooling is switched on - which is not apparent in the figure shown - then the moisture was condensed on the heat exchanger 8. The process air was then circulated until a desired degree of drying is achieved.

LIST OF REFERENCE NUMBERS

1

tub

2

drum

3

laundry

4

drive motor

5

Process air circuit

6

fan

7

air heating

8th

heat exchangers

9

water valve

10

Flushing device for heat exchangers

11

Aqueous liquid

12

sewage pump

13

sewer

14

First temperature sensor T1 between drum and air heater

15

Second temperature sensor T2 at the rear exit

16

Third temperature sensor T3 on the glass door

17

Warm air / steam

18

control device

19

Caustic drain line

20

Water supply system

21

dispenser tray

22

Glass door (filling opening)

23

cuff

24

(Drum) output

25

Transition piece

26

filter

27

Fourth temperature sensor T4 in the water supply system

28

Entrance (into the tub)

Claims (13)

1. Method for operating a washer-dryer, wherein the washer-dryer has an outer tub (1); a drum (2) supported rotatably in the outer tub with a closable glass door (22), wherein the drum (2) is used to receive and remove laundry items (3) when the glass door (22) is opened; a control device (18) and a process air duct (5), in which a heater (7) for heating air, a fan (6), and at least one temperature sensor (14, 15, 16) for measuring a temperature T_pc are disposed, comprising the steps:

   (a) measuring a temperature T _{pc 1} in the process air duct (5) with the at least one temperature sensor (14, 15, 16);

   (b) when the heater (7) is switched on, carrying out a cooling program using the process air in the event that T _{pc 1} ≥ T_pclim , wherein T_pclim is an upper limit temperature of the process air, wherein the cooling program is carried out until a predetermined temperature T_pcset ≤ T_pclim is reached, so that the cooling program achieves a cooling of the process air and as a result the glass door (22), wherein the cooling program comprises putting the warm process air in contact with water from a water supply system (20), wherein the temperature T_pclim is fixed as a function of a temperature T_aq of the water from the water supply system (20) so that a predetermined temperature shock resistance ΔT _shock is not exceeded; and

   (c) carrying out a wash program.
2. Method according to claim 1, characterised in that the at least one temperature sensor (16) measures a temperature of the glass door (22) directly.
3. Method according to claim 1, characterised in that the at least one temperature sensor (14, 15) is arranged at a distance from the glass door (22), and that before the measurement the fan (6) is switched on for a period of time Δt_blow in order to effect a temperature compensation in the process air duct (5).
4. Method according to claim 3, characterised in that the period of time Δt_blow does not exceed a duration of one minute and amounts in particular to approximately 30 seconds.
5. Method according to one of the preceding claims, characterised in that the cooling program comprises routing process air through a heat exchanger (8) arranged in the washer-dryer.
6. Method according to one of the preceding claims, characterised in that the cooling program comprises putting the warm process air in contact with water from a flushing device (10) for a heat exchanger (8).
7. Method according to one of claims 1 to 6, characterised in that the quantity M_c of water used in the cooling program flows into the outer tub (1) and is selected such that it is less than the quantity M_b of water in the outer tub (1) which is required so that a lower end of the drum (2) is immersed in the water.
8. Method according to one of claims 1 to 7, characterised in that the water heated by the warm process air is used to carry out the wash program in step (c).
9. Method according to one of claims 1 to 8, characterised in that the temperature shock resistance ΔT_shock amounts to approximately 100 K.
10. Method according to one of claims 1 to 9, characterised in that the drum (2) is rotated during the cooling program.
11. Method according to claim 10, characterised in that the drum (2) is operated in reverse mode.
12. Washer-dryer, having an outer tub (1); a drum (2) supported rotatably in the outer tub with a closable glass door (22), wherein the drum (2) is used to receive and remove washing items (3) when the glass door (22) is opened; a control device (18) and a process air duct (5), in which a heater (7) for heating air, a fan (6) and at least one temperature sensor (14, 15, 16) for measuring a temperature T_pc are disposed,
    wherein the control device (18) is designed to carry out a method, comprising the steps:

    (a) measuring a temperature T _{pc 1} in the process air duct (5) with the at least one temperature sensor (14, 15, 16);

    (b) when the heater (7) is switched on, carrying out a cooling program using the process air in the event that T _{pe 1} ≥ T_pclim , wherein T_pclim is an upper limit temperature of the process air, wherein the cooling program is carried out until a predetermined temperature T_pcset ≤ T_pclim is reached, so that the cooling program achieves a cooling of the process air and as a result the glass door (22), wherein the cooling program comprises putting the warm process air in contact with water from a water supply system (20), wherein the temperature T_pclim is fixed as a function of a temperature T_aq of the water from the water supply system (20) so that a predetermined temperature shock resistance ΔT_shocck is not exceeded; and

    (c) carrying out a wash program.
13. Washer-dryer according to claim 12, characterised in that in order to measure the temperature T_pc of the process air, a temperature sensor T1 (14) is arranged between a drum entry and the glass door (22), a temperature sensor T2 (15) between a drum exit (24) and the glass door (22) or a temperature sensor T3 (16) on the glass door (22).

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