DE102022207950A1 - Air-heated washing machine and method of operating same - Google Patents

Abstract

The invention relates to a washing machine 1 with a tub 2, in which a drum 3 for receiving items of laundry 9 to be treated is rotatably mounted, a process air duct 5, in which an air heating device 6 and a blower 7 for conveying the air through the drum 3 are arranged are, a temperature sensor 4, 14 and a control unit 8, the control unit 8 being set up to carry out a method in which (a) in a hygiene phase the laundry items 9 are treated with hot air at a temperature TH; (b) in a cooling phase heated items of laundry 9 are cooled to a temperature TW < T with at least one addition of a predetermined amount of water Mset with a temperature Ta ≤ 35 ° C, preferably ≤ 30 ° C and particularly preferably ≤ 25 ° C; and (c) in a washing phase, the cooled items of laundry 9 are washed at the predetermined washing temperature TWset. The invention also relates to a method for operating this washing machine 1.

Description

The invention relates to a washing machine with a tub in which a drum for receiving items of laundry to be treated is rotatably mounted, a process air duct in which an air heating device and a fan for conveying the air through the drum are arranged, a temperature sensor and a control unit; and a procedure for their operation.

Today's washing processes are often carried out at very low temperatures. Although this is gentle on laundry and saves energy, it often cannot or cannot completely kill germs. A hygiene step in which items of laundry are sterilized in a laundry treatment device is therefore generally important. However, particularly sensitive items of laundry that are washed at low temperatures, e.g. 30°C, are damaged at high temperatures when wet. Disinfection by washing at high temperatures is therefore not possible.

The publication DE 10 2011 075 501 A1 describes a process for the gentle disinfection of temperature-sensitive items of laundry with the following features: the items of laundry are exposed in a dry state to a process air flow of a defined temperature over a predetermined period of time, and then the items of laundry heated in this way are brought to a target temperature (Tp) that is significantly reduced compared to the temperature (Tp). _should ) cooled down, for example room temperature. In one embodiment, the cooled items of laundry are then washed in a washing process. Preferably, the target temperature (Tp _target ) is equal to a maximum temperature that occurs during the washing process.

The publication DE10 2007 041 906 B4 describes a method for admitting water into a laundry treatment machine with a drum rotatably mounted in a tub for receiving items of laundry, a water supply system and a drive motor for the drum. To prevent laundry items in the drum from becoming soaked when water is admitted by applying water to an outer wall of the drum, the drum is rotated at a speed that is at least so high that a centrifugal acceleration on an inner wall of the drum is at least 1 g . In this case, an amount of water is preferably let in that is less than the volume available below the drum in the tub, so that the drum does not immerse in the amount of water.

In washer dryers that have a cooling device for process air, treatment with heated air is followed by a cooling step, in which the process air blower continues to operate after the heating is switched off until the air has cooled down sufficiently. This cooled air simultaneously cools the laundry in the drum and the tub and the inner drum rotating within it. The temperature of the air circulated in the circuit and emerging from the tub can be used as a measure of the laundry temperature.

However, air-heated washing machines do not have a cooling device for process air like washer dryers because dehumidification of the process air is not necessary to carry out washing processes. Cooling takes place without further measures only via convection on the tub walls and on the outer walls of the air heating system with heat released to the inside of the housing of the washing machine and thus further through the housing walls to the environment. This cooling takes a very long time and is not very effective. Furthermore, in washer-dryers with the cooling device, the amount of water required for cooling is not predetermined. It would therefore be important to enable improved cooling of the laundry items in order to be able to carry out an improved washing process without waiting for a long time.

Against this background, the object of the present invention was to provide a washing machine with air heating, which enables a combination of gentle hygienization of textiles and a gentle washing process. Preferably, the method to be carried out in the washing machine should be able to run as resource-saving as possible, in particular energy-saving and/or water-saving.

The solution to this problem is achieved according to this invention by a washing machine and a method for operating this washing machine with the features of the corresponding independent patent claims. Preferred embodiments of the washing machine according to the invention and the method according to the invention are listed in the respective dependent patent claims. Preferred embodiments of the method according to the invention correspond to preferred embodiments of the washing machine according to the invention and vice versa, even if this is not explicitly stated herein.

1. (a) in einer Hygienephase die Wäschestücke mit heißer Luft mit einer Temperatur T_H behandelt werden;
2. (b) in einer Abkühlphase die erhitzten Wäschestücke unter mindestens einmaliger Zugabe einer vorbestimmten Wassermenge M_set mit einer Temperatur T_a ≤ 35°C, vorzugsweise ≤ 30°C und besonders bevorzugt ≤ 25°C auf eine Temperatur Tw < T_H abgekühlt werden; und
3. (c) in einer Waschphase die abgekühlten Wäschestücke bei der vorgegebenen Waschtemperatur T_W ^set gewaschen werden.

The subject of the invention is therefore a washing machine with a tub in which a drum is rotatably mounted to hold items of laundry to be treated, a process air duct, in which an air heating device and a fan for conveying the air through the drum are arranged, at least one temperature sensor and a control unit, the control unit being set up to carry out a method in which

1. (a) in a hygiene phase, the laundry items are treated with hot air at a temperature T _H ;
2. (b) in a cooling phase, the heated items of laundry are cooled to a temperature Tw <T H with at least one addition of a predetermined amount of water M _set at a temperature T _a ≤ 35 ° C, preferably ≤ 30 ° C and particularly preferably ≤ 25 ° _C ; and
3. (c) in a washing phase, the cooled items of laundry are washed at the specified washing temperature T _W ^set .

To treat the items of laundry with hot air, the fan is preferably switched on in step (a) of the hygiene phase in order to enable rapid and even heating of the items of laundry and the components of the washing machine that come into contact with the hot air. Furthermore, the cooling phase is preferably monitored in such a way that wetting of the laundry items only occurs when the laundry items have reached a temperature Tw at which washing or wet treatment of the laundry items is possible, whereby the temperature T _W ≥ the predetermined washing temperature T _W ^set can be. This means that the temperature Tw is less than or equal to the temperature at which the wet treatment of the laundry items is still possible without damaging them due to the temperature during the wet treatment.

With the washing machine designed according to the invention, at least part of the amount of water added during the cooling phase can be used particularly advantageously to treat the laundry items in the washing phase, whereby the supply of the amount of water required for the washing phase is reduced or even avoided. In particular, the amount of water last supplied during the cooling phase can remain in the tub and be used as already heated washing liquid for the washing phase.

During the cooling phase, the items of laundry are preferably cooled to a temperature that is not lower than the predetermined washing temperature T _W ^set . This has the particular advantage that the items of laundry and the last amount of water supplied can be avoided from being heated again to the washing temperature T _W ^set . A particularly resource-saving washing machine can thus be provided.

To carry out step (b) of the cooling phase, the control unit of the washing machine is preferably set up so that the heated items of laundry are cooled down in the cooling phase with the fan switched on. This has the particular advantage that the items of laundry and the components heated with the hot air during the hygiene phase can be cooled down more quickly.

In the washing machine, the predetermined washing temperature T _W ^set is preferably <35°C, more preferably <30°C.

The washing machine according to the invention preferably does not have a cooling device for drying warm, moist air. With this development, the washing machine can be provided more cost-effectively because an additional cooling device is avoided.

Furthermore, according to the invention, a washing machine is preferred in which in step (a) T _H ≥ 60 ° C, preferably ≥ 70 ° C and even more preferably ≥ 80 ° C and T _H for a period Δt of at least 10 minutes, preferably at least 15 minutes, is maintained. This can advantageously ensure effective hygiene of the laundry items.

A predetermined amount of water M _set , which is suitable for carrying out method step (b1) described below, results from the design of the washing machine and is preferably so large that the drum does not immerse in the water in the tub. This advantageously ensures that the laundry items are not moistened. This means that sensitive textiles in particular are treated particularly gently and resources are saved, as the amount of water supplied for cooling is limited to the predetermined amount of water.

In a particularly preferred embodiment of the washing machine according to the invention, which is suitable for carrying out method step (b2) described below, it has a device for determining and/or setting a load quantity of laundry items in order to determine the predetermined amount of water M _set . A user could simply set the load amount on the washing machine so that the control unit can pass on appropriately adapted instructions. A particularly suitable device for determining the amount of laundry loaded is a speed-dependent drive motor for the drum, in which the operating data (current, power consumption) is used to determine the amount of laundry become. It is also possible to use a scale.

In a particularly preferred embodiment of the washing machine according to the invention, the control unit is set up to calculate a total heat capacity C _total of the washing system, taking into account the load amount of laundry items and their heat capacity, and to use this to determine the amount of water M _req required for cooling to the temperature T _W , which with the at least one addition of the predetermined amount of water M _set in step (b) of the cooling phase.

By determining the load quantity and, if necessary, further taking the heat capacities into account, the amount of water M _req required for cooling can be predetermined even more precisely and thus enable the cooling of the laundry items to be particularly water-saving.

In one embodiment of the washing machine, which is described in more detail below in connection with the method according to the invention, the required amount of water M _req can be added to the drum in a single step (M _req = M _set , see method step (b2)) or it In one step (see method step (b1)), an amount of water M _set can first be sprayed onto the inner wall of the tub during rotation of the drum at high speed for cooling. Only in a second or further step would the amount of water required to achieve the amount of water M _req be added. This development advantageously ensures that the still hot items of laundry are not moistened due to the drum rotation and/or the determination of the predetermined amount of water M _set before they have cooled down to the temperature Tw possible for wet treatment, in particular to the predetermined washing temperature T _W ^set are. In this way, damage to laundry can be avoided when washing sensitive textiles that have been excessively heated due to sanitation.

This also makes it possible to implement a further cooling option by determining the amount of water filled for washing depending on the current temperature in the system and the amount of laundry. The heat capacity of the washing system can be determined in particular from the specific heat capacity of the materials used and the masses that come into contact with the washing solution. Essentially these are the tub with the drum bearings, the inner drum, the filling window (access window) and, in the case of an air-heated system, the air heating duct. The heat capacity of the laundry items can be determined, for example, from the amount of laundry determined by the control system at the start of the program using a load measurement and an average heat capacity for cotton fabrics. The temperature that arises in the system after the water inlet can be predicted by calculating a mixing temperature if the heat energy stored in the system at the beginning of the filling process is distributed between the system and the incoming water. The inlet temperature T _a for cold water depends on the temperature in the supply system. Depending on the season, this is generally around 15°C, but can reach the ambient room temperature if the inlet pipes are insufficiently insulated. For a sufficient estimate, an inlet temperature T _a of 23°C can be assumed as a precaution. Alternatively, the inlet temperature T _a can also be measured or checked during the water inlet. In this way, a minimum amount of inlet water can be calculated that is necessary to achieve the mixing temperature T _M , which is then equal to the predetermined washing temperature T _W ^set . This target temperature T _W ^set depends on the washing temperature set by the user. In order to prevent damage to textiles, for example with sensitive textiles, a target temperature of 35°C should not be exceeded when the washing temperatures set by the user are ≤ 30°C.

The washing machine according to the invention generally also has a water supply device. This can be, for example, a valve-controlled fresh water connection, with the valve preferably being controllable by the control unit. Particularly preferably, the fresh water supply line to the tub then additionally has a flow sensor or another detection system for determining the volume of fresh water introduced.

A washing machine according to the invention can have an electric water heating device in addition to the air heating device in the tub.

1. (a) in einer Hygienephase die Wäschestücke mit heißer Luft mit einer Temperatur T_H behandelt werden;
2. (b) in einer Abkühlphase die erhitzten Wäschestücke unter mindestens einmaliger Zugabe einer vorbestimmten Wassermenge M_set auf eine Temperatur T_W < T_H abgekühlt werden, wobei die vorbestimmte Wassermenge M_set eine Temperatur T_a ≤ 35°C, vorzugsweise ≤ 30°C und besonders bevorzugt ≤ 25°C hat; und
3. (c) in einer Waschphase die abgekühlten Wäschestücke bei der vorgegebenen Waschtemperatur T_W ^set gewaschen werden.

The invention also relates to a method for operating a washing machine with a tub in which a drum for receiving items of laundry to be treated is rotatably mounted, a process air duct in which an air heating device and a fan for conveying the air through the drum are arranged, at least one temperature sensor and a control unit, the control unit being set up to carry out a method in which

1. (a) in a hygiene phase, the laundry items are treated with hot air at a temperature T _H ;
2. (b) in a cooling phase, the heated items of laundry are cooled to a temperature T _W <T _H with at least one addition of a predetermined amount of water M _set , the predetermined amount of water M _set having a temperature T _a ≤ 35 ° C, preferably ≤ 30 ° C and particularly preferably ≤ 25°C; and
3. (c) in a washing phase, the cooled items of laundry are washed at the specified washing temperature T _W ^set .

With the method according to the invention, the same advantages of the washing machine according to the invention can be achieved.

• (b1) Beaufschlagen der inneren Laugenbehälterwand mit der vorbestimmten Wassermenge M_set während die Trommel mit einer Drehzahl größer 100 Umdrehungen pro Minute, vorzugsweise einer Drehzahl im Bereich von 100 bis 300 Umdrehungen pro Minute, rotiert wird.

In a preferred embodiment of this method, the fan is switched on in step (b) of the cooling phase and additionally includes a step:

• (b1) Applying the predetermined amount of water M _set to the inner tub wall while the drum is rotated at a speed greater than 100 revolutions per minute, preferably a speed in the range from 100 to 300 revolutions per minute.

• (b2) Einfüllen einer Wassermenge M_req in die Trommel, die mit der zumindest einen Zugabe der vorbestimmten Wassermenge M_set im Schritt (b) der Abkühlphase zuzugeben ist und die für eine sofortige Abkühlung der im Schritt (a) erwärmten Wäschestücke auf eine berechnete Mischtemperatur T_M der wässrigen Flüssigkeit genügen würde, wobei die Mischtemperatur T_M unter Verwendung einer bestimmten Wärmekapazität C_total des Waschsystems unter Berücksichtigung der Temperaturabnahme ausgehend von Tw berechnet wird.

In a further advantageous embodiment of this method, step (b) of the cooling phase additionally includes a step:

• (b2) Filling an amount of water M _req into the drum, which is to be added to the cooling phase with the at least one addition of the predetermined amount of water M _set in step (b) and which is used for immediate cooling of the laundry items heated in step (a) to a calculated mixing temperature T _M of the aqueous liquid would be sufficient, the mixing temperature T _M being calculated using a certain heat capacity C _total of the washing system, taking into account the temperature decrease starting from Tw.

In step (b1), the items of laundry can be cooled particularly quickly by cooling the drum, since the items of laundry lie against the drum wall at the preferred speed of the drum, which is well cooled from the outside by the nearby inner tub wall. This makes heat equalization easier. The selected speed of the drum also prevents premature wetting of the laundry items, since water that could possibly get onto the outer wall of the drum is thrown off without wetting the laundry items lying on the inside of the drum wall, which is particularly advantageous for sensitive textiles can be hygienised and cooled dry at higher temperatures without damaging them.

With step (b2), the cooling phase can take place particularly quickly, since only one water supply is carried out and the laundry items come into direct contact with the cooler water, which accelerates the heat exchange even further. This step is particularly suitable for less sensitive textiles, which can also be treated wet at higher temperatures. Furthermore, with this step it can be avoided that water that has been heated in the cooling step may have to be removed by pumping it out for a subsequent cooling step, whereby water can be saved.

Steps (b1) and (b2) can also be advantageously combined with one another by first carrying out step (b1) in order to achieve a first cooling of the laundry items to a temperature T _W at which wet treatment of the textiles is possible, and then Step (b2) takes place in order to achieve cooling directly to the predetermined washing temperature T _W ^set with this step at the end of the cooling phase, whereby a new supply of washing water and its heating in the washing phase following step (c) are advantageously avoided .

• (b3) Ermitteln einer Temperatur Tw der Wäschestücke, insbesondere auf Basis einer mittels des Temperatursensors T2 gemessenen Temperatur T_L der Luft;
• (b4) Vergleich der im Schritt (b3) ermittelten Temperatur Tw mit der vorgegebenen Waschtemperatur T_W ^set; und
• (b5) Zugabe von weiterem Wasser mit einer Temperatur T_a bis zum Erreichen der vorgegebenen Waschtemperatur T_W ^set.

In a preferred embodiment of this method, the following steps (b3), (b4) and (b5) are additionally carried out in step (b) of the cooling phase.

• (b3) determining a temperature Tw of the laundry items, in particular based on a temperature T _L of the air measured by the temperature sensor T2;
• (b4) Comparison of the temperature Tw determined in step (b3) with the specified washing temperature T _W ^set ; and
• (b5) Addition of further water at a temperature T _a until the specified washing temperature T _W ^set is reached.

Steps (b3), (b4) and (b5) are carried out particularly advantageously when the inlet temperature T _a of the water is >23 ° C (assumed cooling water temperature when calculating the amount of water M _req ) and the temperature _Tres is above the target temperature T _W ^set is.

According to the invention, it is preferred that a predetermined compensation time is waited before measuring the temperature T _L or before determining the temperature Tw of the laundry items.

In one embodiment of the method, which is particularly suitable for method step (b1), a temperature sensor (eg T2) is arranged in the process air duct at the outlet of the tub. When the fan is switched on, this temperature sensor can be used to easily determine the temperature Tw of the laundry items. Preferably, with the fan switched on and the drum speed increased, the amount of water M _set is filled in so that the drum is not immersed in water in the tub.

Then, in process step (b1), a compensation time is generally waited for, in which this filled water absorbs heat, in particular from the laundry items, the drum, the tub wall and the air. This water is then usually pumped out. This procedure can advantageously be repeated until a target temperature is reached.

In a further embodiment of the method, which is particularly suitable for method step (b2), the temperature sensor can also be arranged in the tub below the drum, where the temperature Tw is determined by measuring a temperature T _res of the aqueous liquid in the tub below the drum of the laundry items can be determined.

In method step (b2), it is also preferred that a predetermined compensation time is waited for before measuring the temperature T _L or the temperature T _res of the aqueous liquid. In order to ensure a sufficiently low washing temperature even at elevated inlet temperatures >23°C, the water temperature in the tub can be measured after an equalization time of, for example, approx. 1 minute and, if necessary, additional fresh water can be supplied to achieve a target temperature of 35°C, for example to fall below. The amount of water filled to reach a target temperature may be increased compared to the amount of water normally used for washing. However, since no further heating by the heating system is necessary in the subsequent washing phase, no additional energy is required to heat the water.

According to the invention, it is preferred that in the cooling phase, in particular in step (b1), the addition of water at the temperature T _a only takes place after the warm water in the tub has been pumped out.

If the step of adding water takes place in a final step during a cooling phase, detergent can also advantageously be rinsed in with this. This usually takes place in process step (b2). Afterwards, the aqueous liquid containing detergent is no longer pumped out of the tub.

If a predetermined amount of water W _set for a washing phase is exceeded due to the addition of further water in step (b5), a reversing rhythm of the drum and/or the duration of the washing phase is preferably adjusted, usually by reducing it, so that the same washing result as in a washing phase without a previous hygiene phase.

Steps (b1) and (b2) can be carried out individually or one after the other.

With step (b1) it is possible to fill a defined amount of water into the tub without the drum being immersed in this water. A cooling function can be achieved by a successive series of filling in cold water, waiting, especially with the fan switched on, and then pumping out the water heated by the warm air.

If both process steps (b1) and (b2) are used for cooling, then, for example, a transition from the first to the second process step can take place depending on the selected washing temperature in such a way that no further heating of the water used is required, even at higher washing temperatures. For this purpose, the control unit can use a minimum amount of inlet water depending on the detected load amount in order to estimate the mixing temperature T _M. This allows the target system temperature for cooling according to method (b1) to be set so that the desired washing temperature T _W ^set is already achieved after the minimum amount of water has been added. This procedure results in energy savings by eliminating the need to reheat the wash liquor (washing liquor).

The invention has numerous advantages. The method according to the invention thus enables the cooling of an air-heated washing machine during the transition from a hygiene phase to a washing phase and its control. The realization of this laundry hygiene is therefore advantageously possible in an air-heated washing machine without the condensation device required in the washer-dryer. However, the invention is not limited to an air-heated washing machine, but can also be implemented in a washer-dryer, whereby the condensation device or its cooling device of the washer-dryer is not activated when the laundry is hygienised, but the hygienization is implemented in the washer-dryer according to the invention.

• 1: eine Waschmaschine in schematischer Darstellung und
• 2: zeitliche Kurvenverläufe von Parameter und Betriebswerten eines Verfahrens zum Betrieb der Waschmaschine

A non-limiting exemplary embodiment of a washing machine according to the invention is explained in more detail below with reference to the attached figures. Show it:

• 1 : a washing machine in a schematic representation and
• 2 : Time curves of parameters and operating values of a method for operating the washing machine

1. (a) in einer Hygienephase 22 die Wäschestücke 9 mit heißer Luft mit einer Temperatur T_H behandelt werden;
2. (b) in einer Abkühlphase 23 und/ oder 24 die erhitzten Wäschestücke 9, insbesondere bei eingeschaltetem Gebläse 7, unter mindestens einmaliger Zugabe einer vorbestimmten Wassermenge M_set mit einer Temperatur T_a ≤ 35°C, vorzugsweise ≤ 30°C und besonders bevorzugt ≤ 25°C auf eine Temperatur T_W < T_H abgekühlt werden; und
3. (c) in einer Waschphase 25 die abgekühlten Wäschestücke 9 bei der vorgegebenen Waschtemperatur T_W ^set gewaschen werden.

The 1 shows a washing machine 1 with a tub 2, in which a drum 3 for receiving items of laundry 9 to be treated is rotatably mounted, with a temperature sensor 4 being arranged below the drum 3 in this non-limiting embodiment, a process air duct 5, in which an air heating device 6 and a fan 7 for conveying the air through the drum 3 are arranged, and a control unit 8, which is set up to carry out a method in which

1. (a) in a hygiene phase 22, the laundry items 9 are treated with hot air at a temperature T _H ;
2. (b) in a cooling phase 23 and/or 24, the heated items of laundry 9, in particular with the fan 7 switched on, with at least one addition of a predetermined amount of water M _set with a temperature T _a ≤ 35 ° C, preferably ≤ 30 ° C and particularly preferably ≤ 25 ° C to a temperature T _W < T _H ; and
3. (c) in a washing phase 25, the cooled laundry items 9 are washed at the predetermined washing temperature T _W ^set .

For better monitoring of the heating of the process air, a temperature sensor T1 13 is located in the process air duct 5 downstream behind the air heating device 6, while a temperature sensor T2 14 is located in the process air duct 5 upstream in front of the fan 7. 17 means an inner wall of the tub, which can be supplied with water in the process step (b1) described below, which, however, is not visible in more detail in the figure. The wetting of the outer drum wall, on the other hand, should be reduced as much as possible or even prevented by rotating the drum 3 at high speed and a water level below this outer drum wall.

An aqueous liquid from the tub 2 can be conveyed back into the interior of the drum 3 through a channel 11 for aqueous liquid from the tub 2 by means of the pumping pump 16 via a pumping line 11. Alternatively, the aqueous liquid from the tub 2 can be disposed of via a sewer or wastewater hose 12 using the wastewater pump 15.

10 means a drive motor for the drum and 19 means an access door for the drum 3.

The 2 shows time curves of a non-limiting example of the method according to the invention. The abscissa axis 20 (X axis) is shown for the time parameter, with the sequence of the sections of the method being shown. The first section is the hygiene phase 22, which includes a first cooling phase 23, which in particular includes method step (b1). This is followed by a second cooling phase 24, which in particular includes process step (b2), which is followed by the washing phase 25. Of the washing phase 25 is in the 2 only the beginning is shown. The duration of the washing phase can also be longer depending on the laundry treatment program selected. Furthermore, further phases (not shown), such as rinsing, spinning and/or drying, of a set laundry treatment program can follow the sections shown.

In the 2 is a first ordinate axis 21 (Y-axis) for the parameters rotation speed n of the drum 3 (with respect to the curve shown 26), temperature T of the temperature sensor T1 (with respect to the curve shown 30) and the temperature sensor T2 (with respect to the curve 29 shown), temperature Tw of the laundry items (with respect to the curve 28 shown) and total amount of water (with respect to the curve 27 shown). Furthermore, a second ordinate axis 31 (Y-axis) for switching states of the air heating device 6 (curve 32), the blower 7 (curve 33), one not in the 1 shown valve (curve 35) of a water supply device and the waste water pump 15 (curve 34). The curves 32, 33, 34 and 35 representing the switching state indicate the binary state of the respective electrical component, with a high curve value meaning the activation (switch-on state) and a low curve value meaning the deactivation (switch-off state) of the respective component.

At the beginning of the hygiene phase 22, the waste water pump 15 can be activated briefly in order to pump out any residual water remaining in the washing machine 1 from a previous treatment program, this step not being shown in the curve 34. Furthermore, at the beginning of the hygiene phase 22, as in curve 35 2 shown, the valve can be activated briefly in order to supply a minimal amount of water into the tub 2, in order to avoid wetting of the laundry items 9 during the water supply Drum 3 is rotated at a speed greater than 100 rpm, as shown at the beginning of curve 26. The water supplied can be evaporated during the subsequent heating, which advantageously enables faster heat transfer from the heated air to the laundry items 9 and the components in the air circuit, such as the tub 2 and the drum 3. The pumping and water supply steps at the beginning of hygiene phase 22 are optional.

To heat the laundry items 9 and the components of the washing machine 1, in particular the process air duct 5, the drum 3 and the tub 2, the air heating device 6 and the fan 7 are activated at the beginning of the hygiene phase 22. The air is thus heated and supplied to the laundry items 9, the drum 3 and the tub 2 with the fan 7. The temperature T1 at the entry of the air into the tub 2 rises quickly, as shown in curve 30. When the predetermined target temperature T _H is reached, which is preferably greater than or equal to 60 ° C, the air heating device 6 is deactivated. The temperature value T1 is used to control the air heating device 6, ie it is deactivated when an upper limit value of T1 is exceeded and activated again when it falls below it, so that the temperature T1 fluctuates around the target temperature T _H. The target temperature T _H is maintained for a period Δt of at least 10 minutes. The target temperature T _H and the period Δt are predetermined in such a way that safe and efficient hygienization of the laundry items 9 and the components of the washing machine 1 is ensured.

While the air is being heated and the target temperature is maintained, the fan 7 is activated and the drum 3 is rotated reversibly at a low speed at which the laundry items 9 can be moved in the drum 3 in order to achieve uniform heating. In the 2 The curves of the temperature of an item of laundry (curve 28) and the temperature T _L of the air at the temperature sensor T2 at the outlet of the tub 2 (curve 29) are also shown. Since the heated air is cooled by a heat transfer to the laundry items 9 and the components of the washing machine 1, the temperature T2 of the air at the outlet of the tub 2 is lower than the temperature T1 of the air at the inlet of the tub 2. A comparison of the curves 28 and 29 shows that the temperature T _L at the temperature sensor T2 of the air is similar to the temperature T _W of the laundry items 9, in particular during the hygiene phase 22, which is why a temperature T _L measured with the temperature sensor T2 can advantageously be used to determine the temperature Tw of the laundry items 9 can. In the cooling phase, the temperature T2, which is measured at the end of a compensation time after adding a predetermined amount of water M _set , can preferably be used to approximately determine the temperature T _W of the laundry items 9.

The hygiene phase 22 ends when the period Δt for maintaining the target temperature T _H has expired and, in the exemplary embodiment, this is followed by a first cooling phase 23 and a second cooling phase 24, which are as in 2 shown follow one another. In alternative examples, only either the first cooling phase 23 or the second cooling phase 24 can be implemented. Even during the first cooling phase 23, the blower 7 preferably remains activated, with the wastewater pump 15 being activated at the beginning of the first cooling phase 23 in order to remove heated water from the tub 2. Then the valve for supplying a predetermined amount of water M _set , which is applied to an inner tub wall 17, is activated briefly. The valve, not shown, has a fluid connection to the air circuit. While the amount of water M _set is being supplied, the drum 3 is rotated at a speed greater than 100 revolutions per minute in order to avoid wetting the laundry items. In the present exemplary embodiment, the water is preferably supplied between the outlet of the tub 2 and the blower 7 into the process air duct 5, which means that wetting of the laundry items 9 can also be largely avoided. The water can also be fed into the air circuit at other points. Depending on the water supply system, the water supplied has a temperature Ta ≤ 35 ° C, preferably ≤ 30 ° C and particularly preferably ≤ 25 ° C, and collects in the lower part of the tub 2. The components in this area and the air flowing past are cooled , which then also cools down the other components of the washing machine and the laundry items 9. The temperature T _a of the water supplied can be checked with another temperature sensor 4 arranged below the drum 3 in the tub 2.

The water supplied heats up during an equalization time, which is why the warm water in the tub 2 is pumped out after the equalization time. The steps of supplying water with a temperature T _a ≤ 35°C and pumping it out again are repeated several times, as in 2 you can see. During this first cooling phase 23, the temperature Tw of the laundry items 9 also cools down, as shown, for example, in curve 28.

The temperature Tw of the laundry items 9 can be measured during the cooling phase 23 preferably by means of a direct measurement or an indirect measurement, for example as described above can be monitored by evaluating the temperature T _L, , measured with the temperature sensor T2 at the end of the respective compensation time of a method step (b1). If the temperature Tw of the items of laundry 9 is sufficiently reduced so that no damage to the laundry is to be expected due to wet treatment that is too warm, the further cooling of the items of laundry 9 can be carried out with a process step (b2), in which a larger predetermined amount of water M _{is used} than in the process step ( b1) is supplied. Whether the laundry items 9 have already cooled down sufficiently for wet treatment can be determined depending on the specified washing temperature, a specified treatment program and/or a set or determined type of textile.

In the in 2 In the exemplary embodiment shown, the first cooling phase 23 is followed by a second cooling phase 24 comprising the method step (b2), in which an amount of water M _req is filled into the drum 3, which ensures immediate cooling of the heated laundry items 9, which occur during the first cooling phase 23 have not yet been cooled to a predetermined washing temperature T _W ^set , to a calculated mixing temperature T _M of the aqueous liquid is sufficient, the mixing temperature T _M being calculated using a specific heat capacity C _total of the washing system, taking into account the temperature decrease starting from Tw.

The immediate cooling is achieved in particular by direct contact of the laundry items 9 with the supplied amount of water M _req . Therefore, in this process step, the amount of water M _req is preferably chosen to be so large that wetting is possible. The drum 3 can also rotate at a speed of greater than 100 rpm, as in 2 provided as an example, omitted. The second cooling phase 24 preferably takes place when the laundry has already cooled down sufficiently for wet treatment due to a previous cooling phase, when there are no sensitive textiles to be washed or when the predetermined washing temperature T _W ^set has been chosen so high that the laundry items 9 are only slightly need to be cooled down.

After adding the amount of water M _req, the washing phase 25 follows without any further addition of water. During the washing phase 25, further addition of washing liquid can take place. The further phases of a selected treatment program following the washing phase 25 are in 2 not shown.

Reference symbol list

1

washing machine

2

Lye container

3

drum

4

Temperature sensor in the tub below the drum

5

Process air duct

6

Air heating device

7

Fan for moving air through the drum

8th

Control unit

9

laundry items

10

Drive motor (for the drum)

11

pumping channel

12

Sewer, hose

13

Temperature sensor T1 in the process air duct (behind the air heating device, in front of the drum)

14

Temperature sensor T2 in the process air duct (in front of the air heating device and the fan, at the outlet of the tub 2)

15

sewage pump

16

circulation pump

17

Inner wall of the tub

18

Channel for aqueous liquid from the tub

19

Access door

20

Abscissa axis (X-axis) for the parameter time t

21

First ordinate axis (Y-axis) for the parameters rotation speed n of the drum 3, temperature T of the temperature sensors T1 and T2, temperature Tw of the laundry items and the total amount of water supplied

22

Hygiene phase, first part of the procedure

23

First cooling phase, second stage of the process

24

Second cooling phase, third stage of the process

25

Washing phase, fourth stage of the process

26

Course of the rotation speed n of the drum 3

27

Course of the total amount of water supplied

28

History of the temperature Tw of an item of laundry

29

Course of the temperature T _L recorded with the temperature sensor T2

30

Course of the temperature T recorded with the temperature sensor T1

31

Second ordinate axis (Y-axis) for switching states of the air heating device 6, the blower 7, a valve of a water supply device and the wastewater pump 15

32

Course of the switching state (ON-OFF) of the air heating device 6

33

History of the switching state (ON-OFF) of the fan 7

34

Course of the switching state (ON-OFF) of the wastewater pump 15

35

Course of the switching state (ON-OFF) of the valve of the water supply device

Ta

Water inlet temperature

TL

Air temperature at temperature sensor T2

TH

Target temperature of the hot air in front of the drum

TM

Mixing temperature of the aqueous liquid

Tres

Temperature of the aqueous liquid in the tub below the drum

Tw

Temperature of the laundry items

TWset

specified washing temperature

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102011075501 A1 [0003]
• DE 102007041906 B4 [0004]

Claims (15)

Washing machine (1) with a tub (2) in which a drum (3) is rotatably mounted to hold items of laundry (9) to be treated, a process air duct (5) in which an air heating device (6) and a fan (7) for conveying the air through the drum (3), at least one temperature sensor (4, 13, 14) and a control unit (8), the control unit (8) being set up to carry out a method in which (a) in a hygiene phase (22) the items of laundry (9) are treated with hot air at a temperature T _H ; (b) in a cooling phase (23, 24), the heated items of laundry (9) are cooled to a temperature T _W <T _H ; and (c) in a washing phase (25) the cooled items of laundry (9) are washed at the predetermined washing temperature T _W ^set , characterized in that the control unit (8) is set up to carry out step (b), in which in the Cooling phase (23, 24) the heated laundry items (9) with at least one addition of a predetermined amount of water M _set at a temperature T _a ≤ 35 ° C, preferably ≤ 30 ° C and particularly preferably ≤ 25 ° C to the temperature Tw < T _H be cooled down. washing machine (1). Claim 1 , characterized in that the control unit (8) is set up to carry out step (b) of the cooling phase (23, 24) such that in the cooling phase (23, 24) the heated items of laundry (9) are cooled with the fan (7) switched on become. washing machine (1). Claim 1 or 2 , characterized in that the predetermined washing temperature T _W ^set is <35°C, preferably <30°C. Washing machine (1) according to one of the Claims 1 until 3 , characterized in that it has no cooling device for drying warm, moist air. Washing machine (1) according to one of the Claims 1 until 4 , characterized in that in step (a) T _H ≥ 60 ° C and T _H is maintained for a period Δt of at least 10 minutes. Washing machine (1) according to one of the Claims 1 until 5 , characterized in that to determine the predetermined amount of water M _set it has a device for determining and/or setting a load amount of laundry items (9). washing machine (1). Claim 6 , characterized in that the control unit (8) is set up to calculate a total heat capacity C _total of the washing system, taking into account the load quantity of laundry items (9) and their heat capacity, and to determine the amount of water M required for cooling to the predetermined washing temperature T _W ^set _req , which is to be added with the at least one addition of the predetermined amount of water M _set in step (b) of the cooling phase (23, 24). Method for operating a washing machine (1) with a tub (2) in which a drum (3) for receiving items of laundry (9) to be treated is rotatably mounted, a process air duct (5) in which an air heating device (6) and a Blowers (7) are arranged for conveying the air through the drum (3), at least one temperature sensor (4, 13, 14) and a control unit (8), the control unit (8) being set up to carry out a method in which (a) in a hygiene phase (22) the laundry items (9) are treated with hot air at a temperature T _H ; (b) in a cooling phase (23, 24), the heated items of laundry (9) are cooled to a temperature T _W <T _H ; and (c) in a washing phase (25) the cooled items of laundry (9) are washed at the predetermined washing temperature T _W ^set , characterized in that in step (b) of the method in the cooling phase (23, 24) the heated items of laundry ( 9) are cooled to the temperature T _W <T _H with at least one addition of a predetermined amount of water M _set , the predetermined amount of water M _set having a temperature T _a ≤ 35 ° C, preferably ≤ 30 ° C and particularly preferably ≤ 25 ° C . Procedure according to Claim 8 , characterized in that in step (b) of the cooling phase (23, 24) the fan (7) is switched on and that step (b) additionally includes a step: (b1) applying the predetermined amount of water to the inner tub wall (17). M _set while the drum (3) is rotating at a speed greater than 100 revolutions per minute. Procedure according to Claim 8 or 9 , characterized in that in step (b) of the cooling phase (23, 24) the step is additionally carried out: (b2) filling an amount of water M _req into the drum (3), which with the at least one addition of the predetermined amount of water M _set im Step (b) is to be added to the cooling phase (23, 24) and for immediate cooling the heat in step (a). th items of laundry (9) to a calculated mixing temperature T _M of the aqueous liquid would be sufficient, the mixing temperature T _M being calculated using a specific heat capacity C _total of the washing system, taking into account the temperature decrease starting from Tw. Procedure according to one of the Claims 8 until 10 , characterized in that in step (b) of the cooling phase (23, 24) the following steps are additionally carried out: (b3) determining a temperature Tw of the laundry items (9), in particular based on a temperature measured by means of the temperature sensor T2 (14). T _L of air; (b4) Comparison of the temperature Tw of the laundry items (9) determined in step (b3) with the predetermined washing temperature T _W ^set ; and (b5) adding further water at a temperature T _a until the predetermined washing temperature T _W ^set is reached. Procedure according to Claim 11 , characterized in that a predetermined compensation time is waited before determining the temperature Tw of the laundry items (9). Procedure according to one of the Claims 8 until 12 , characterized in that in the cooling phase (23, 24) the addition of water at the temperature T _a only takes place after the warm water in the tub (2) has been pumped out. Procedure according to one of the Claims 8 until 13 , characterized in that if a predetermined amount of water W _set for a washing phase (25) is exceeded, a reversing rhythm of the drum (3) and / or the duration of the washing phase is adjusted due to the addition of further water in step (b5), so that the same Washing result as achieved in a washing phase (25) without a previous hygiene phase (22). Procedure according to Claim 14 , characterized in that the reversing rhythm of the drum (3) and/or the duration of the washing phase (25) are reduced.

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