METHOD FOR PERFORMING A TREATMENT PROGRAM FOR A LAUNDRY TREATMENT DEVICE, AND LAUNDRY TREATMENT DEVICE

Description

[0001] The invention relates to a method for carrying out a treatment program for a laundry treatment appliance, and to a laundry treatment appliance with a control device for carrying out said method.

[0002] Laundry treatment appliances, such as washer-dryers, can have an additional electric heater in addition to a heat pump to warm the laundry.

[0003] US 2015 / 0096 190 A1 discloses a method for operating a laundry treatment appliance with a heat pump and an auxiliary heater. The temperature of the process air is monitored to prevent the compressor from overheating. As soon as the temperature deviates from a predetermined value, the auxiliary heater is switched off, or the heat pump stops operating if a defective compressor is detected. US 2019 / 276978 A1 also discloses a method for operating a laundry treatment appliance with a heat pump and an auxiliary heater. The heat pump is switched on again after being switched off if it is determined that the laundry is not yet dry.

[0004] The invention has for its object to provide an improved method for carrying out a treatment program for a laundry treatment appliance and an improved laundry treatment appliance.

[0005] According to the invention, this object is achieved by a method for carrying out a treatment program for a laundry treatment appliance, and by a laundry treatment appliance having the features of the main claims. Advantageous embodiments and further developments of the invention are set forth in the following subclaims.

[0006] The advantages achieved with the invention include protecting the compressor from damage and reducing acoustic noise.

[0007] A method is presented for carrying out a treatment program for a laundry treatment appliance, wherein the laundry treatment appliance comprises a drum for holding laundry, a heat pump for tempering process air, a heating unit for heating the process air, a process air blower for conveying the process air through a circuit out of the drum and through the heat pump and the heating unit back into the drum, a temperature sensor for providing a temperature signal representing a temperature in the drum, a compressor temperature sensor for providing a compressor temperature signal representing a temperature of a compressor of the heat pump, and a control device for controlling the treatment program, and wherein the method comprises the following steps: Outputting a switch-on signal to an interface to the heat pump to cause the process air to be heated, outputting a heating signal to an interface to the heating unit to cause the process air to be heated, outputting a process air signal to an interface to the process air blower to convey the process air through the circuit, outputting a switch-off signal to the interface to the heat pump to switch off the heat pump when a switch-off criterion dependent on the temperature signal or the compressor temperature signal is met, and outputting the switch-on signal again to the interface to the heat pump to switch on the heat pump when a switch-on criterion dependent on the compressor temperature signal is met.

[0008] A laundry treatment appliance can be understood as an appliance in which laundry, for example textiles, can be treated. For example, this can be a washer-dryer or a tumble dryer. A treatment program can be understood as a drying program or a hygiene program, for example. During operation of the laundry treatment appliance, the laundry can be arranged in the drum in a laundry treatment chamber and treated using process air. A heat pump can be understood as a device in which components are functionally connected to one another in order to heat the process air flowing through it. For example, the process air can first flow through an evaporator and then a condenser. A refrigerant can be arranged or can be arranged in a refrigerant circuit of the heat pump.The refrigerant can be evaporated in the evaporator using moist process air and condensed in the condenser using the dehumidified process air. The compressor and a throttle can also be arranged in the refrigerant circuit. Thus, the heat pump device can be used to take in the moist process air, for example from a laundry treatment room enclosed by the drum, cool it and dry it, reheat it, and release it again. In addition, the laundry treatment appliance comprises a heating unit, which can be electrically operated, for example, and can be designed to heat the process air independently of the heat pump. For example, the process air, driven by the process air fan, can flow in a circuit through both the heat pump and the heating unit and be heated either by the heat pump or by the heating unit, or by both simultaneously.The heat pump and heating unit can be switched on and off using the control device. The heated process air can then be used to heat the drum of the laundry treatment appliance and thus the laundry arranged in the drum, for example, during the treatment program. For this purpose, in the process presented here, after a heating phase in which the process air is heated by both the heating unit and the heat pump, the heat pump can be switched off when, for example, a predefined target temperature in the drum or at the compressor is reached. From a process engineering perspective, it may make sense to generate the heating output of individual treatment programs exclusively via an additional electric heater.Under these circumstances, however, the heat pump's compressor, which can also be referred to as the condenser, can be damaged because the compressor can have a low heat level throughout the program if it is not running. The refrigerant, on the other hand, can absorb heat energy from the process air in the heat exchangers, which increases the enthalpy of the refrigerant and can cause it to evaporate. Two different heat levels can then collide in the compressor: a refrigerant with high enthalpy and a compressor with low enthalpy. The refrigerant can give up some of its heat energy to the compressor, which can lead to condensation of the refrigerant. Since liquid refrigerant cannot be compressed, a subsequent start-up of the compressor would lead to damage and increased acoustics.To circumvent this, the method presented here restarts the heat pump when a switch-on criterion dependent on the compressor temperature signal is met, such as a drop in the compressor temperature to a predefined value. This typically relatively brief restart of the heat pump can protect it.

[0009] According to one embodiment, after the step of reissuing the switch-on signal, a step of reissuing the switch-off signal can occur if a switch-off criterion dependent on the compressor temperature signal is met. For example, the heat pump can be switched off again after a predetermined period of time or when a certain temperature is reached. This has the advantage that the heating power of the treatment program can be largely generated by the heating unit.

[0010] In addition, the steps of reissuing the switch-on signal and reissuing the switch-off signal can be performed repeatedly. For example, the heat pump can be switched on and off several times over the course of the treatment program. This advantageously allows the compressor temperature to be maintained at a level throughout the program, preventing condensation of the refrigerant and thus damage to the compressor.

[0011] According to one embodiment, the switch-off signal can be output in the outputting step if the temperature signal represents a temperature corresponding to a predetermined target temperature value. In this case, the switch-on signal can be output in the re-outputting step if the compressor temperature signal represents a temperature corresponding to a predetermined threshold temperature value, wherein the threshold temperature value can be lower than the target temperature value. For example, the heat pump can be switched off above a defined target temperature, which can also be referred to as the hot gas temperature. The target temperature can be, for example, the temperature required for drying the laundry in the corresponding treatment program, for example 65°C. The heating-up phase is thus ended and the program can only be operated with the additional electric heater.This state can be maintained until the temperature in the compressor falls below a second defined value, at which condensation of the refrigerant in the compressor is likely. If this occurs, the compressor can be controlled again until the defined target temperature is reached again, at which point the heat pump can be shut down again. This process can be repeated several times during a hygiene program and advantageously ensures that the compressor always maintains a certain temperature level, thus preventing condensation inside.

[0012] The predetermined target temperature value may be at least 60°C, and additionally or alternatively, the threshold temperature value may be at least 40°C. Advantageously, a treatment program can be optimally performed at a temperature of at least 60°C.

[0013] According to a further embodiment, the shutdown signal can be output in the re-outputting step if a temperature represented by the compressor temperature signal is greater by a temperature difference than a temperature represented by the temperature signal. For example, the heat pump can be switched off if the temperature in the compressor is at least 15K greater than the temperature in the drum. Condensation inside the compressor can advantageously be prevented by switching the heat pump on and off in direct relation to the temperature conditions in the drum and in the compressor.

[0014] Furthermore, in the re-issuing step, the switch-on signal can be issued if a temperature represented by the compressor temperature signal is lower than a temperature represented by the temperature signal by a temperature difference. For example, if the temperature in the compressor drops to a lower temperature value than the temperature in the drum, the heat pump can be switched on again. The temperature difference can, for example, correspond to the difference that results in the switch-off signal being issued again, for example a temperature difference of 15K. Condensation inside the compressor can advantageously be prevented by switching the heat pump on and off in direct relation to the temperature conditions in the drum and in the compressor.

[0015] The temperature difference can be between 10K and 20K. For example, the heat pump can be switched on again when the difference between the temperature in the compressor and the temperature in the drum is 15K. This can advantageously define a temperature difference at which condensation is expected.

[0016] According to a further embodiment, the method can comprise a step of outputting a pump signal to an interface to a pump unit of the laundry treatment appliance in order to pump atomized water into the drum. For example, the step of outputting the pump signal can occur before the steps of outputting the switch-on signal and the heating signal. For this purpose, for example, a pump can be switched on to moisten dry laundry with finely atomized water, which can be pumped, for example, from a condensate container and sprayed into the drum. The process air can then be heated so that the water in the drum can evaporate. Advantageously, a combination of increased air humidity with increased temperature as part of a hygiene program can enable a reduction in germs in the laundry to be treated.Alternatively, the step of outputting the pump signal can also occur after the steps of outputting the switch-on signal and the heating signal. For example, the process air and the laundry arranged with it in the drum can be heated to a predetermined temperature before it can be humidified by the pump as a result of the pump signal. This has the advantage that the laundry absorbs less water during the subsequent humidification. This allows the humidity to be maintained at a higher level, and advantageously, less water is required.

[0017] According to a further embodiment, the method can comprise a step of outputting a reversing signal to an interface to a drive of the drum in order to bring about a reversing state of the drum. For example, the drum of the laundry treatment appliance can be designed as a reversing drum, whereby a rotation process in two directions can advantageously be possible. In this case, for example, the drive of the drum can bring about a change in the direction of rotation. Such a reversing state can be carried out, for example, in response to the reversing signal. Advantageously, the laundry can be optimally dried with heated process air in the reversing state. In addition, using a reversing drum, for example, the laundry can also be moistened in the reversing state in order to advantageously achieve optimal moistening of the laundry.Otherwise, the volume flow generated by the process air blower would ensure that the nebulized water is directed into, for example, a filter in the device and not into the laundry.

[0018] According to a further embodiment, the treatment program can represent a hygiene program, and the method can comprise a step of terminating the hygiene program after a predetermined period of time following the step of outputting the shutdown signal. By means of a hygiene program, the laundry in the laundry treatment appliance can advantageously not only be dried but also experience a reduction in germs. The hygiene program can be used, for example, to hygienically process laundry that has already been washed and additionally or alternatively partially dried. This can be advantageous, for example, if laundry is not removed from the washing machine directly after a wash cycle, but is left in the closed drum for a while, for example, several hours. In such a case or a similar case, the laundry can, for example, be moistened and heated to reduce any germs that have developed.To limit the duration of such a program, the control device can, for example, comprise a counter that can count down a predetermined period of time, for example, 30 minutes, following the step of issuing the shutdown signal, i.e., at the end of the heating phase. During this period, the temperature in the drum can be maintained at a target temperature by means of the heating unit. Advantageously, the hygiene program can be terminated automatically after the expiration of the period.

[0019] Although the approach described is based on a household appliance, the method described here can be used accordingly in connection with a commercial or professional device, for example a medical device such as a cleaning or disinfection device.

[0020] The approach presented here further provides a device designed to perform, control, or implement the steps of a variant of a method presented here in corresponding devices. This embodiment of the invention in the form of a device also allows the problem underlying the invention to be solved quickly and efficiently.

[0021] The device can be designed to read in input signals and to determine and provide output signals using the input signals. An input signal can, for example, represent a sensor signal that can be read in via an input interface of the device. An output signal can represent a control signal or a data signal that can be provided at an output interface of the device. The device can be designed to determine the output signals using a processing rule implemented in hardware or software. For example, the device can comprise a logic circuit, an integrated circuit, or a software module and can, for example, be implemented as a discrete component or be comprised of a discrete component.

[0022] In addition, a laundry treatment appliance for treating laundry using a treatment program with a variant of the previously presented control device is presented. In addition to the control device, the laundry treatment appliance has the following features: a drum for holding laundry, a heat pump for tempering process air, a heating unit for heating the process air, a process air blower for conveying the process air through a circuit out of the drum and through the heat pump and the heating unit back into the drum, a temperature sensor for providing a temperature signal representing a temperature in the drum, and a compressor temperature sensor for providing a compressor temperature signal representing a temperature of a compressor of the heat pump.

[0023] Advantageously, the previously presented method for carrying out a treatment program can be optimally implemented in such a laundry treatment appliance.

[0024] Also advantageous is a computer program product or computer program with program code that can be stored on a machine-readable carrier or storage medium such as a semiconductor memory, a hard disk memory, or an optical memory. If the program product or program is executed on a computer or device, the program product or program can be used to carry out, implement, and / or control the steps of the method according to one of the embodiments described above.

[0025] An embodiment of the invention is shown purely schematically in the drawings and is described in more detail below. It shows Figure 1 shows a schematic representation of a laundry treatment appliance according to an embodiment; Figure 2 shows a flowchart of an embodiment of a method for carrying out a treatment program; Figure 3 shows a flowchart of an embodiment of a method for carrying out a treatment program; Figure 4 shows a diagram of an embodiment of a temperature-dependent control of the compressor; Figure 5 shows a diagram of an embodiment of a temperature-dependent control of the compressor.

[0026] Figure 1shows a schematic representation of a laundry treatment appliance 100 according to an exemplary embodiment. The laundry treatment appliance 100 comprises a drum 105 for receiving laundry, which is designed solely as an example as a reversing drum in order to circulate the laundry in a reversing state in two different rotation directions by means of a drive 107 and, in this exemplary embodiment, in response to a reversing signal 110. The reversing signal 110 can be provided solely as an example by a control device 115. The control device 115 is also designed to receive a temperature signal 125 provided by a temperature sensor 120 arranged on the drum 105, wherein the temperature signal 125 represents a temperature in the drum 105.

[0027] The laundry treatment appliance 100 is configured to perform a treatment program that allows laundry to be dried. According to one embodiment, the treatment program can be implemented as a hygiene program, in which the laundry can first be moistened to achieve an improved hygiene result.

[0028] The laundry treatment appliance 100 further comprises a heat pump 130, which is designed to regulate the temperature of process air within the laundry treatment appliance 100. For this purpose, the heat pump 130 has, by way of example only, an evaporator 132, a compressor 134, a condenser 136, and a throttle 138. In this exemplary embodiment, the heat pump 130 can be switched on by the control device 115 using a switch-on signal 140, wherein the switch-on signal 140 can be output, by way of example only, at the beginning of a treatment program for drying laundry arranged in the drum 105 in order to heat process air guided by the heat pump 130. A compressor temperature sensor 144 assigned to the compressor 134 is designed to detect a temperature of the compressor 134 and to provide a compressor temperature signal 146 representing the temperature of the compressor 134 to the control device 115.The compressor temperature sensor 144 is designed here as a refrigerant temperature sensor (NTC), which detects the temperature of the refrigerant on the pressure side of the compressor 134. The temperature of the compressor 134 can be determined from the refrigerant temperature. Alternatively, the temperature of the compressor can be detected via a temperature sensor located directly on the compressor 134.

[0029] Using the compressor temperature signal 146, the control device 115 is configured to provide a shutdown signal 150 to the heat pump 130 to shut it down when a shutdown criterion dependent on the temperature signal 125 is met. For example only, the shutdown criterion in this exemplary embodiment consists in reaching a predetermined target temperature value of, for example, 65°C in the drum 105.

[0030] At the same time, the control device 115 is configured to reissue the switch-on signal 140 and thus switch the heat pump 130 back on when a switch-on criterion dependent on the compressor temperature signal 146 is met. For example only, the switch-on criterion in this exemplary embodiment is when the temperature of the compressor 134 falls below a predetermined threshold temperature value, wherein the threshold temperature value corresponds to 40°C, for example only. During the treatment program, the heat pump 130 can thus be activated and deactivated several times.

[0031] In addition to the heat pump 130, the laundry treatment appliance 100 in this exemplary embodiment includes a heating unit 160 designed to heat the process air. For this purpose, the heating unit 160 can be controlled by the control device 115 using a heating signal 165. Thus, both the heat pump 130 and the heating unit 160 are designed to heat the process air.

[0032] In this exemplary embodiment, a process air blower 170 is configured to circulate the process air out of the drum 105, through the heat pump 130 and the heating unit 160, and back into the drum 105. Optionally, the process air in the circuit is further conveyed through a filter 172. In this exemplary embodiment, the process air blower 170 can also be controlled by the control device 115 using a process air signal 175.

[0033] By way of example only, the laundry treatment appliance 100 in this exemplary embodiment also comprises a pump unit 180 for pumping nebulized water into the drum 105. By pumping in water, the laundry in the drum 105 can be moistened, for example, during a hygiene program to reduce germs. By way of example only, the pump unit 180 is designed to draw water from a condenser tank 182 for pumping. In this exemplary embodiment, the water can be pumped into the condensate tank 182 by a condensate pump 185 after it has condensed in the circuit of the heat pump 130. In this exemplary embodiment, the pump unit 180 can be controlled by a control device 115 by means of a pump signal 190.

[0034] Thus, the control device 115 is designed to control the execution of a treatment program by controlling the individual components of the laundry treatment appliance 100.

[0035] Figure 2shows a flowchart of an embodiment of a method 200 for carrying out a treatment program. The method can be carried out merely by way of example in a laundry treatment appliance as described in the previous figure. The method 200 comprises a step 205 of outputting a switch-on signal to an interface to a heat pump of the laundry treatment appliance in order to heat process air, and a step 210 of outputting a heating signal to an interface to the heating unit in order to also heat the process air. At the beginning of the program, the heat pump is therefore also operated in addition to the electric heater. This increases the temperature of the heat pump's compressor and shortens the system's heating phase.The method 200 further comprises a step 215 of outputting a process air signal to an interface to the process air blower in order to convey the process air in a circuit through the drum, the heat pump, and the heating unit. In this exemplary embodiment, steps 205, 210, 215 of outputting the switch-on signal, the heating signal, and the process air signal are performed in direct succession. In another exemplary embodiment, steps 205, 210, 215 can also be performed in parallel or simultaneously or in another suitable order. In any case, the process air is heated by both the heat pump and the heating unit during the heating phase, i.e., until a temperature corresponding to a predetermined target temperature is reached in the drum of the laundry treatment appliance. For example only, the target temperature in this exemplary embodiment is 65°C.

[0036] Upon reaching this target temperature value, the heating phase ends in this exemplary embodiment, and in response to a temperature signal representing the target temperature value, a step 220 follows in which a shutdown signal is output to the interface to the heat pump in order to shut down the heat pump. In an alternative exemplary embodiment, the shutdown signal can be output as a result of a different shutdown criterion, for example, if a temperature in the compressor of the heat pump is higher than a temperature in the drum by a predetermined temperature difference, for example a difference of 15K. In other words, in this exemplary embodiment, the heat pump is shut down above a defined hot gas temperature, which is continuously measured, for example, via a thermistor (NTC).The heating phase is thus completed, and the program should be operated solely with the auxiliary electric heater during a subsequent treatment phase. For example, the treatment phase extends until the end of the treatment program, so that after the heating phase, the process air is tempered exclusively using the heating unit, if possible. To prevent damage to the deactivated heat pump during the treatment phase, the heat pump can be temporarily activated.

[0037] For example, the state in which the heat pump is deactivated is maintained until the temperature of the heat pump's compressor, which can also be referred to as the hot gas temperature, falls below a second defined value, i.e., a predetermined threshold temperature value. In this exemplary embodiment, the threshold temperature value is 40°C and is thus lower than the target temperature value. As soon as the compressor temperature signal represents a temperature corresponding to the threshold temperature value, the heat pump is controlled again in a step 225 of re-issuing the switch-on signal to the interface to the heat pump in order to switch the heat pump on. The heat pump is now, for example, in operation again until the temperature of the compressor once again approximately corresponds to the temperature of the drum, i.e., until the target temperature value is reached.In one embodiment, a step 227 of reissuing a shutdown signal follows to shut down the heat pump again. For example only, steps 225 and 227 of reissuing the switch-on signal and reissuing the shutdown signal are repeatedly executed during the treatment phase, and the heat pump is repeatedly switched on and off. This process ensures that the compressor always maintains a certain heat level, thus preventing condensation inside.

[0038] In one embodiment, after a predetermined period of time, for example 30 minutes, after step 220 of first outputting the shutdown signal, a step 230 of terminating the treatment program follows.

[0039] Figure 3shows a flowchart of an embodiment of a method 200 for implementing a hygiene program. The method 200 corresponds to or is similar to the method described in the previous Figure 2illustrated method, wherein in this embodiment the treatment program is executed as a hygiene program. For this purpose, step 205 of outputting the switch-on signal is preceded by a step 305 of outputting a reversing signal to an interface to a drive of the drum and a step 310 of outputting a pump signal to an interface to a pump unit of the laundry treatment appliance. In step 305 of outputting the reversing signal, the drum of the laundry treatment appliance, which is designed as a reversing drum, is controlled to be put into a reversing state. Thus, in the following step 310 of outputting a pump signal, the laundry in the drum is evenly moistened with atomized water that is pumped into the drum. The subsequent steps 210, 215 of outputting a switch-on signal and a heating signal heat the damp laundry in order to reduce germs.

[0040] Figure 4shows a diagram of an embodiment of a temperature-dependent control of a compressor of a heat pump of a laundry treatment appliance during the execution of a treatment program, as described in the previous Figure 1 was described.

[0041] Sub-Figure 4A depicts an activity state 400 of the compressor, which is repeatedly switched on and off during the treatment program. In this exemplary embodiment, the compressor control is directly dependent on a compressor temperature 405 of the compressor, as depicted in sub-Figure 4B, and on a process air temperature 410 of the process air passed through the heat pump, as depicted in sub-Figure 4C. In this exemplary embodiment, the process air temperature 410 corresponds to the temperature in the drum of the laundry treatment appliance.

[0042] In the illustration shown here, the compressor is switched on with the start 415 of the treatment program. At this point in time, the compressor temperature 405, as well as the process air temperature 410, correspond, for example, to an installation temperature of the laundry treatment appliance of, for example, only 18°C. During a heating phase 420, the temperature increases, with the compressor temperature 405 rising faster than the process air temperature 410. During the heating phase 420, according to one embodiment, both the heat pump and an additional heating unit are used to heat the process air.

[0043] When a target temperature value 425 is reached, of merely 60°C for example, the compressor is switched off and the compressor temperature 405 drops again, while the process air temperature 410 continues to rise slightly, for example due to the continued operation of the heating unit, for example until the temperature in the drum also corresponds to the target temperature value or a further target temperature value. While the heat pump is switched off, the compressor temperature 405 in this exemplary embodiment drops to a predetermined threshold temperature value 430 of merely 40°C for example. Upon reaching this threshold temperature value 430, the compressor is switched on again, the compressor temperature 405 rises again to the target temperature value 425, whereupon the compressor is switched off again. The heat pump is thus temporarily switched on for a maintenance phase 440.During the maintenance phase 440, the heating unit is also switched on according to one embodiment.

[0044] During the further execution of the treatment program, the compressor can be switched on and off several times if the compressor temperature 405 repeatedly falls below the threshold temperature value 430 and then returns to the target temperature value. By temporarily switching the compressor back on, the heat pump can be protected from damage. Thus, depending on the situation, several maintenance phases 440 can be performed until the treatment program is completed.

[0045] According to an alternative embodiment, the heating phase 420 is terminated when the process air temperature 410 reaches a corresponding target temperature value.

[0046] Figure 5shows a diagram of an embodiment of a temperature-dependent control of a compressor. The compressor control shown here in sub-figure 5A, which can also be referred to as compressor control, is similar to that in the previous Figure 4 described.

[0047] In this embodiment, the compressor is also shut down when the compressor temperature 405 reaches the target temperature value 425. This terminates the heating phase 420. Alternatively, the heating phase 420 is terminated when the process air temperature 410 reaches a corresponding target temperature value.

[0048] According to this exemplary embodiment, the compressor is switched on again when the compressor temperature 405 is lower than the process air temperature 410. The maintenance phase 440 that begins with this is ended according to this exemplary embodiment when a predetermined temperature difference exists between the compressor temperature 405 and the process air temperature 410, for example, when the compressor temperature 405 is more than 15K higher than the process air temperature 410. In another exemplary embodiment, the temperature difference is, for example, between 10K and 20K. At the end of the maintenance phase 440, the compressor and thus the heat pump are switched off. The further temperature control of the process air then takes place solely via the heating unit until a new maintenance phase 440 begins.Such a renewed maintenance phase 440 begins with the compressor being switched on again as soon as the compressor temperature 405 is again lower than the process air temperature 410.

Claims

1. Method (200) for carrying out a treatment program for a laundry treatment appliance (100), wherein the laundry treatment appliance (100) comprises a drum (105) for receiving laundry, a heat pump (130) for controlling the temperature of process air, a heating unit (160) for heating the process air, a process air blower (170) for conveying the process air through a circuit out of the drum (105) and through the heat pump (130) and the heating unit (160) and back into the drum (105), a temperature sensor (120) for providing a temperature signal (125) representing a temperature in the drum (105), a compressor temperature sensor (144) for providing a compressor temperature signal (146) representing a temperature of a compressor (134) of the heat pump (130) and a control device (115) for controlling the treatment program, and wherein the method (200) has the following steps: Outputting (205) a switch-on signal (140) to an interface with the heat pump (130) to cause heating of the process air; Outputting (210) a heating signal (165) to an interface with the heating unit (160) to cause heating of the process air; Outputting (215) a process air signal (175) to an interface with the process air blower (170) to convey the process air through the circuit; Outputting (220) a switch-off signal (150) to the interface with the heat pump (130) to switch the heat pump (130) off when a switch-off criterion dependent on the temperature signal (125) or the compressor temperature signal (146) is met; and Renewed outputting (225) of the switch-on signal (140) to the interface with the heat pump (130) to switch on the heat pump (130) when a switch-on criterion dependent on the compressor temperature signal (146) is met to keep the temperature of the compressor (134) during the duration of the treatment program at a level at which condensation of the refrigerant in the compressor (134) is avoided.

2. Method (200) according to claim 1, wherein after the step (225) of renewed outputting of the switch-on signal (140), a step (227) of renewed outputting of the switch-off signal (150) takes place if a switch-off criterion dependent on the compressor temperature signal (146) is met.

3. Method (200) according to claim 2, wherein the steps (225, 227) of renewed outputting of the switch-on signal (140) and renewed outputting of the switch-off signal (150) are repeatedly carried out.

4. Method (200) according to any of the preceding claims, wherein in the outputting step (220) the switch-off signal (150) is output when the temperature signal (125) represents a temperature corresponding to a predetermined target temperature value (425) and wherein in the renewed outputting step (225) the switch-on signal (140) is output if the compressor temperature signal (146) represents a temperature corresponding to a predetermined threshold temperature value (430), wherein the threshold temperature value (430) is smaller than the target temperature value (425).

5. Method (200) according to claim 4, wherein the predetermined target temperature value (425) is at least 60°C and / or the threshold temperature value (430) is at least 40°C.

6. Method (200) according to any of claims 2 to 5, wherein in the renewed outputting step (227) the switch-off signal (150) is output when a temperature represented by the compressor temperature signal (146) is greater than a temperature represented by the temperature signal (125) by a temperature difference.

7. Method (200) according to any of claims 2 to 6, wherein in the renewed outputting step (225) the switch-on signal (140) is output when a temperature represented by the compressor temperature signal (146) is smaller than a temperature represented by the temperature signal (125) by a temperature difference.

8. Method (200) according to one of claims 6 to 7, wherein the temperature difference is between 10K and 20K.

9. Method (200) according to any of the preceding claims, comprising a step (310) of outputting a pump signal (190) to an interface with a pump unit (180) of the laundry treatment appliance (100) to cause nebulised water being pumped into the drum (105).

10. Method (200) according to any of the preceding claims, comprising a step (305) of outputting a reversing signal (110) to an interface with a drive (107) of the drum (105) to cause a reversing state of the drum (105).

11. Method (200) according to any of the preceding claims, wherein the treatment program represents a hygiene program and the method (200) comprises a step (230) of terminating the hygiene program after a predetermined period of time, after the step (220) of outputting the switch-off signal (150).

12. Laundry treatment appliance (100) for treating laundry, wherein the laundry treatment appliance (100) comprises the following features: a drum (105) for receiving laundry; a heat pump (130) for controlling the temperature of process air; a heating unit (160) for heating the process air; a process air blower (170) for conveying the process air through a circuit out of the drum (105) and through the heat pump (130) and the heating unit (160) and back into the drum (105); a temperature sensor (120) for providing a temperature signal (125) representing a temperature in the drum (105); a compressor temperature sensor (144) for providing a compressor temperature signal (146) representing a temperature of a compressor (134) of the heat pump (130); and a control device (115) designed for carrying out and / or controlling the steps (205, 210, 215, 220, 225) of the method (200) according to any of the preceding claims in the corresponding units.