EP3274499B1 - Method for carrying out a hygiene program in a dryer comprising a heat pump, and dryer which is suitable for this purpose - Google Patents

Description

The invention relates to a method for carrying out a hygiene program in a dryer with a drum for items to be dried, a process air circuit in which a blower for the transport of process air is arranged, a control unit, a heat pump cycle with an evaporator, a condenser, a throttle and a compressor, and at least one sensor, wherein by means of the sensor, the decrease of the moisture of the laundry items is monitored. The invention also relates to a dryer which is particularly suitable for carrying out this process.

Such a method and dryer will be apparent from the publication DE 10 2007 018 787 A1 ,

In a dryer, heated air (so-called process air) is passed through a drying chamber containing a moist object, usually a drum, through a blower. The hot air absorbs moisture from the objects to be dried. After passing through the drying chamber, the then moist process air is passed into a heat exchanger, which can be preceded by a filter, in particular a lint filter, for filtering out dirt particles, in particular fluff in the case of a tumble dryer or washer-dryer.

This drying process is energy-intensive, because as a rule, the process air is energetically lost before the application of heat to the objects to be dried supplied with the cooling of the process air in the heat exchanger process. By using a heat pump, this energy loss can be significantly reduced. The heat pump can be used to extract heat from the process air flowing from the moist objects, which acts on a corresponding heat sink, and to conduct this heat by means of a suitable pumping device to a heat source, from which it passes to the process air, before they are to be dried Objects, usually wet laundry, acted upon. Alternatively, heat can also be removed by means of the heat sink from an environment of the dryer and fed to the process air via the heat source.

In a dryer equipped with a compressor-type heat pump (also referred to herein as a "compressor type"), the warm, moisture-laden process air is cooled essentially in a heat sink evaporator of the heat pump, where the heat transferred to evaporate a heat exchanger in the heat pump circulating refrigerant is used. The vaporized refrigerant reaches the compressor (also referred to as "compressor") and is compressed there. The refrigerant circulating in the refrigerant circuit (also referred to herein as the "heat pump cycle") is driven by the compressor so that the compressor supplies the energy needed to operate the pumping process The liquefied refrigerant flows through a restrictor, where its internal pressure is reduced, back to the evaporator, which closes the circuit.The restrictor is in particular executable as valve, orifice or capillary tube Condensed water is then generally collected in a suitable container.

A heat pump clothes dryer with a compressor-type heat pump generally has a closed process air cycle and a heat pump cycle. If process air is sent through the drum loaded with damp laundry, the process air is loaded with water vapor, so that the process air can have a relative humidity of up to 100%. A drying process can be subdivided into three successive phases, namely a heating phase, a quasi-stationary drying phase and a transient drying phase. In the heating phase, process air and damp laundry items are generally heated up to a first maximum temperature value T _p at which temperature during the quasi-stationary drying phase the laundry items are dried, in particular with regard to the surface water. During the drying process, the relative humidity of the process air decreases, with the beginning of the transient drying phase, in general, the temperature of the process air at the drum outlet increases. This is due in particular to the fact that the surface water of the wet laundry is essentially evaporated and the drying phase is dominated by so-called deep drying of the laundry. However, this temperature increase takes place only gradually. In a dryer equipped with a heat pump, since the temperature in a laundry drum is generally relatively low, for example By 40 ° C, the temperature rise towards the end of a drying process is too slow to ensure the necessary for a hygienic effect, ie germ killing, high temperature for a sufficiently long period. Finally, prolonged heating of already dry items of laundry would be energetically disadvantageous at the end of a drying process.

It would therefore be desirable to have a hygiene program in which a hygienic effect can be achieved with less energy input.

For the operation of a heat pump dryer, it is advantageous if the heat pump cycle can be controlled. For this purpose, for example, a compressor with a variable power consumption can be used. Heat pump dryer with a compressor with a variable capacity are known per se.

This is how the publication describes EP 2 284 310 A1 a dryer with at least one heat pump system, the dryer comprising a process air circuit with a drum for laundry to be dried, at least one cooling circuit comprising a variable speed compressor, first and second heat exchangers for each thermal coupling between the process air circuit and the cooling circuit, a control unit for controlling the rotational speed of the compressor and at least one sensor for the measurement of at least one physical parameter of the process air flow, the coolant and / or the laundry as a function of time contains. A central control unit is arranged to evaluate the time evolution of the parameters and to reduce the rotational speed of the compressor in accordance with the evaluation of the time dependence of the parameters.

The publication DE 10 2005 041 145 A1 describes a clothes dryer in which the warm air used to dry the laundry is heated using a heat pump heating system including a variable power compressor. In one embodiment, the tumble dryer includes a controller that controls the performance of the compressor in response to the temperature outside the tumble dryer.

The publication EP 2 182 104 A describes a washer-dryer with a compressor-type heat pump containing a speed-controllable compressor motor, such as a DC brushless motor, and a temperature sensor for measuring the outside temperature. The construction of the washer-dryer is intended to ensure that the use of a tubular butterfly valve with a fixed orifice prevents the formation of frost on the evaporator when the compressor motor is at rest.

The publication EP 2 415 927 A describes a clothes dryer with a heat pump containing a variable speed compressor. This can be avoided that a temperature of the refrigerant in the refrigerant circuit of the heat pump is too high.

The publication EP 2 735 643 A1 describes a method of controlling a tumble dryer with a blower motor for operating a blower for drying air at a variable speed and a drum motor for driving the laundry drum. The speed of the fan motor is regulated on the basis of the power consumption or the electric current of the drum motor.

The publication EP 1 775 368 A1 describes a washer-dryer comprising a control unit arranged to control the on and off phases of a fan and moreover to control the speed of rotation of the fan. Described is also a method for drying wet laundry, in which the rotational speeds of the fan in a first and an adjoining second drying phase differ in that the flow rate of the air in the first drying phase is greater.

The publication DE 10 2007 018 787 A1 describes a method for operating a condensation dryer with a drying chamber for the objects to be dried, a process air circuit in which a heater for heating the process air and heated process air is guided by means of a blower over the objects to be dried, and a heat pump circuit with an evaporator, a compressor and a condenser, and a sensor arrangement for determining a humidity in the objects to be dried. The humidity is determined and until heated to a predetermined value (F) of the humidity in the range of 0% to 12%, the process air through the condenser and after falling below the predetermined value, the heater is switched on and operated in such a way that over a period of at least 5 minutes in the drying chamber Air temperature of at least 70 ° C is. The method should be suitable for disinfecting the objects, which are in particular laundry items. However, additional conventional heating is required for disinfection. The heat pump can not be used because it can not or only work poorly at the high temperatures of the process air, which are required for disinfecting.

Hygiene programs are known, for example, in washing machines and washer-dryers. That's how it describes DE 197 51 028 A1 a method for performing a hygiene program in a program-controlled washing machine or a program-controlled washer-dryer with a tub for receiving washing liquid and a rotatably mounted therein drum, wherein the tub is filled with water having at least a temperature of 70 ° C or to a temperature of heated at least 70 ° C, the drum during the heating and / or for a fixed first period after reaching the wash temperature of at least 70 ° C is driven at washing speed and then the drum is rotated at an increased speed.

Against this background, it was an object of the present invention to provide a method for carrying out a hygiene program in a dryer with a heat pump, which allows an efficient hygienic effect, without requiring an increased energy expenditure is required. Preferably, this hygiene program should be as short as possible and possibly lead to no or only a short extension of a drying program. The object of the invention was also to provide a suitable dryer for carrying out this method.

The solution of this object is achieved according to this invention by a method for carrying out a hygiene program in a dryer and a dryer with the features of the respective independent claim. Preferred embodiments of the method and the dryer according to the invention are listed in respective dependent claims, preferred embodiments of the dryer according to the invention correspond to preferred embodiments of the method according to the invention and vice versa, even if this is not expressly stated herein.

The invention thus provides a method for carrying out a hygiene program in a dryer with a drum for items to be dried, a process air circuit in which a blower for the transport of process air is arranged, a control unit, a heat pump with an evaporator, a condenser, a Throttle and a compressor, and at least one sensor, wherein by means of the sensor, the decrease in moisture F _{W of} the laundry is monitored and upon reaching a predetermined lower humidity F _W ^lowlim a speed u of the fan is reduced and / or a power consumption p of a ^variable- power compressor is increased, so that a temperature required for efficient germ killing in the drum of at least 65 ° C is reached.

These measures generally lead to a more rapid heating of the process air leaving the drum, so that a high temperature required for efficient germ killing can be achieved comparatively quickly and thus early.

According to the invention, the rotational speed u of the blower is reduced and / or the power consumption p of the variable-power compressor is increased until a temperature T _{H of} the process air of at least 65 ° C, preferably at least 70 ° C is reached. Most preferably, the temperature T _{H of} the process air for a hygiene effect without damaging laundry in the range of 70 to 75 ° C.

It is also preferred that the speed u and / or the power consumption p be controlled so that the temperature T _{H of} the process air is maintained for a predetermined period .DELTA.t. The period .DELTA.t is preferably at least 15 minutes, more preferably at least 17 minutes, and .DELTA.t is very particularly preferably in the range from 18 to 25 minutes.

By means of the sensor according to the invention the decrease of the moisture F _{W of} the laundry items is monitored. This can be done in very different ways, whereby different measuring principles of a sensor can occur, if necessary. Also in combination.

Thus, for example, a temperature and / or a relative humidity at the drum outlet or a moisture content of the laundry items in the drum can be measured as a function of time.

The predetermined lower humidity F _W ^lowlim the laundry items can be achieved depending on the specification in different drying ^phases or at transitions between drying ^phases . According to the invention, it has been shown that the lower moisture F _W ^{lowlim is} preferably in a range of 5 to 15%, particularly preferably 8 to 12%, based on the mass of the laundry items. This is also referred to as "residual moisture content (ERF)".

In a preferred embodiment, signals from the sensor are evaluated to detect a transition from a quasi-stationary to a transient drying phase and, upon a detected transition, the speed u of the fan is reduced and / or the power consumption p of the variable-power compressor is increased.

The term "sensor" as used herein means a single sensor or system of sensors.

In a preferred embodiment, by means of the sensor in the drying program, in particular in a transient drying phase, further sensor signals S _i measured and evaluated with regard to increasing drying of the laundry, so that the speed u of the fan and the power consumption p of the compressor according to a desired temperature increase or increased according to a desired increase in temperature over time. That is, in this embodiment, the drying process is monitored even after reaching a predetermined lower humidity of F _W ^lowlim .

Preferably, a conductivity sensor is used as the sensor, with the Leitwertsensor the conductance L _{w of} the laundry is measured as a function of time t, and wherein the predetermined lower humidity F _W ^{lowlim is} reached when a predetermined lower conductance L _W ^{min of} the laundry items and / or a predetermined minimum value (ΔL _W / Δt) _{min is reached} for the amount of the time decrease of the conductance L _w .

In particular, a transition from the quasi-stationary to the non-stationary drying phase can be determined by using the conductance sensor in the drum. This is the case, in particular, when a predetermined lower conductance L _w ^{min of} the items of laundry and / or a predetermined minimum value (ΔL _W / Δt) _min for the amount of the time reduction of the conductance L _{w is} reached. The predefined lower conductance L _W ^{min of} the items of laundry could, for example, correspond to the condition "ironing". In the transition, experience has shown that the relative humidity at the drum outlet begins to drop significantly.

In a further preferred embodiment, a relative humidity F _rel of the process air leaving the drum is measured at an outlet of the drum with a humidity sensor. If the measured relative humidity F _{rel reaches} a value which corresponds to the predetermined lower humidity F _W ^lowlim , the speed u of the fan is reduced and the power consumption p of the compressor is increased for a predetermined period Δt _set such that a desired temperature increase can be achieved.

Moreover, in the heat pump _cycle, a temperature T _{KM of} a refrigerant is preferably measured by means of a temperature sensor S ^T _KM and the power consumption p of the variable-power compressor is controlled such that the temperature T _KM lies within a range T _KM ¹ ≦ T _KM ≦ T _KM ² . In this case, it is again advantageous that by means of the arranged in the heat pump circuit temperature sensor S ^T _KM a temperature T _{KM of} the refrigerant is measured and at a reaching or exceeding a maximum allowable refrigerant temperature T _KM ^max, the power consumption p of the power-dependent compressor is reduced.

The value of T _KM ^max depends on the type of refrigerant and the location of the temperature sensor in the heat pump cycle. For example, T _KM ^{max may be} very close to a maximum temperature specified by the manufacturer of a refrigerant for efficient and safe use of the refrigerant. Another factor may be the maximum allowable coil temperature of the drive motor of the compressor. This is influenced by the insulation used and is for example 115 ° C. Another limiting factor influencing T _KM ^max has, is the lubricant used in the compressor. Excessively high temperatures can lead to carbonization and thus failure of the lubricant and eventually failure of the compressor. An important factor is also the pressure of the gaseous refrigerant behind the compressor, which must be compared with the strength of the tubes used.

When operating a dryer, it makes sense to protect the dryer as well as the laundry items to be dried therein that the temperature of the process air is not too high. Therefore, in the method according to the invention, a temperature T _{PL of} the process air is preferably measured by means of a temperature sensor S ^T _PL arranged in the process air circuit, and the power consumption p of the compressor is reduced when a predefined maximum permissible process air temperature T _PL ^{max is} reached. If an additional fan is present, it cools down the compressor with ambient air in a first step. If necessary, then in a second step, in general, the compressor is shut down in the case of an unregulated compressor or in the case of a controlled compressor, the minimum allowed speed of the compressor is controlled. Only then, if necessary, the compressor would be turned off. Preferably, the compressor is switched off when a critical process air temperature T _PL ^crit > T _PL ^{max is} reached or exceeded. If present, the temperature sensor S ^T _{PL is} preferably arranged between the drum and the evaporator.

For example, three separate drive motors can be used to drive the drum, blower and, if present, power variable compressor. However, it has proven to be advantageous that a common power variable drive motor is used for driving the fan and the drum. The variable capacity compressor generally uses a separate drive motor.

The variable-power compressor is preferably a compressor driven by a BLDC motor, in particular a screw compressor or a rotary compressor.

According to the invention, it is preferred that the power-dependent compressor is a variable-speed compressor whose speed ω _{K is} varied as a function of the speed u of the fan and / or the sensor signals of the sensor, wherein in the control unit a relationship between the speed ω _K and the speed u and / or the aforementioned sensor signals (eg moisture of the laundry) is deposited. It is preferred that the rotational speed ω _{K of} the variable-speed compressor is varied as a function of a conductance L _{W of} the laundry items measured by a conductivity sensor and / or a change in time ΔL _W / Δt of the conductance, a relationship between the control unit being stored in the control unit Speed ω _K and the measured conductivity L _W and / or the time change ΔL _W / Δt is used.

Preferably, the load of the drum with laundry is taken into account for carrying out the method. In particular, the loading of the drum with laundry items by the control unit is taken into account by storing in the control unit a relationship between a conductivity L _W , a power consumption p of the variable-power compressor and the load with the laundry. In this case, the loading can be entered manually by a user of the dryer or automatically determined by an optional suitable measuring device in the dryer, such as a balance.

In the method according to the invention, the outside temperature T _R can advantageously be taken into account in an installation room of the dryer. The waste heat losses of the dryer are dependent on the ambient temperature. At a high ambient temperature, the temperature difference between the heat-emitting surfaces in the dryer, which may also be referred to as convection surfaces, eg the drum, is lower to the ambient temperature, resulting in lower energy losses due to convection. This leads to a higher end temperature of the heat pump cycle, ie the refrigerant circuit, which can be critical and would lead to switching on a fan or another heat exchanger, if present in the dryer. In the prior art, the amount of heat dissipated by the process air is usually controlled via an additional fan. This would increase the waste heat losses. A regulation of the heat pump cycle by means of a variable-power compressor avoids this problem.

In a preferred embodiment, therefore, the method is adapted to the outside temperature of a Aufstellraumes of the dryer by using a temperature sensor S ^T _AR a temperature T _{R is} measured in the installation room and the variable-power compressor is operated with a power consumption p, which is additionally dependent on the measured temperature T _R , so that the temperature of a refrigerant in the heat pump cycle is within a range T _KM ¹ ≤ T _KM ≤ T _KM ² . The variable-power compressor is in particular a screw compressor or a rotary piston compressor. Preferably, a speed-controlled compressor is used as a power-dependent compressor whose speed ω _{K is} varied in dependence on the measured temperature T _R.

Alternatively or in addition thereto, the rotational speed u of the fan is selected as a function of the outside temperature T _R , for which purpose a relationship between the rotational speed u and the outside temperature T _{R is} stored in the control unit. These values can advantageously also be stored in the control unit for different values of the conductivity L _{W of} the items of laundry.

Preferably, in the method according to the invention, a rotational speed ω _{K of} a variable-speed compressor as a function of a conductance L _{W of} the items of laundry and optionally the outside temperature T _R in an installation room of the dryer is based on a relationship between the speed ω _K and the conductance L _W stored in the control unit and possibly the temperature T _R varies.

The temperature T _R in the installation room is measured with a temperature sensor S ^T _AR , which can be arranged at different locations on the dryer, for example in contact with the installation room or inside the dryer. In the latter case, however, it should be ensured that a heat-generating and thus the temperature-increasing operation of the dryer is sufficiently long ago or due to a suitable thermal insulation, the measurement of the temperature T _R can not or hardly affect, so that a temperature measured inside the dryer as Measure of the temperature T _R can be used.

In a preferred embodiment of the method according to the invention, the outside temperature T _{R is} measured in the installation room with a temperature sensor S ^T _PL arranged in the process air cycle, if a predetermined time interval t _{set has} elapsed since a last drying process was carried out and the temperature of the process air was measured.

In a drying process, the temperature of the process air rises gradually. As already mentioned, in the heating phase process air and damp laundry items are generally heated up to a first maximum temperature value T _p . In order for this increase in temperature to take place as quickly as possible, in a preferred embodiment of the method according to the invention, the speed-dependent compressor is at a power consumption p until a predetermined temperature T _p at which the temporal increase in the temperature T _{PL of} the process air has dropped to a minimum value. which is in the range of 0.9 to 1 p _max operated. Here, p _{max is} the maximum power consumption of the compressor.

The invention also relates to a dryer with a drum for laundry to be dried, for laundry items to be dried, a process air circuit in which a blower for the transport of process air is arranged, a control unit, a heat pump cycle with an evaporator, a condenser, a throttle and a compressor, and at least one sensor, wherein the control unit is adapted for performing a method in which the decrease in the moisture F _W of the laundry articles is monitored by means of the sensor, and wherein the control unit is adapted to, upon reaching a predetermined lower moisture F _W ^lowlim to reduce a speed u of the blower and / or to increase a power consumption p of a ^variable- power compressor, so that a temperature required for efficient germ killing in the drum of at least 65 ° C is reached.

The compressor used in the dryer according to the invention is preferably a screw compressor or a rotary piston compressor, in particular a rotary piston compressor.

If present in the dryer according to the invention, the temperature sensor or sensors preferably have an elongate body with a temperature-sensitive tip. A preferred temperature sensor is an NTC sensor. Advantageously, the temperature sensor S ^T _{PL is} inclined in the process air circuit in the direction of the evaporator.

The dryer according to the invention generally has a condensate tray for collecting the condensate occurring in the evaporator and optionally in another heat exchanger. From the condensate pan, the condensate is either by manual Draining or draining by means of a condensate pump in a condensate tank, which in turn can be emptied manually, or disposed of directly into a sewer system.

In the dryer according to the invention, a heat pump and an air-to-air heat exchanger can be used simultaneously. In this case, heat pump and air-air heat exchanger can complement the cooling of moist, warm process air, for example, the fact that the air-air heat exchanger is used in particular in the event of impending overheating of the refrigerant.

For more rapid heating of the process air, an electric heating device may additionally be present in the dryer according to the invention. If, in one embodiment, the dryer comprises an additional electric heating device, a more rapid heating of the process air and thus a more rapid execution of a drying process in the dryer are possible. However, this would affect a possible energy savings.

The dryer of the invention preferably also comprises an optical and / or acoustic display device which allows the user of the dryer to view e.g. Operating parameters and / or an expected duration of the drying process allows.

The invention has numerous advantages. Thus, the invention makes it possible for an efficient hygiene program to be carried out in a dryer, in which effective germ killing can be achieved in an energy-efficient manner. Finally, the method according to the invention allows a comparatively short hygiene program, wherein in embodiments of the invention a drying program is not extended even when a hygiene program is carried out. Due to a total possible shorter drying program, ie a shorter drying time, thermal losses are reduced, resulting in energy savings. Moreover, there is an energy savings in that no over-drying of the laundry is required. Even if the method according to the invention is carried out only at a final residual moisture content of 0%, the invention makes it possible for a hygiene program to run even faster and to be terminated than hitherto.

The inventive method and dryer according to the invention also have in embodiments the advantage that a drying program can be carried out with a hygiene program in which different installation conditions and different weather conditions and seasons can be optimally taken into account by an outdoor temperature in the installation room of the dryer is taken into account.

In addition, it is possible to take into account the sensitivity of garments such as those made of wool, silk or lace by the hygiene program, the temperature of the process air and the duration of the hygiene program can be adapted to the type of garments. This can be done by changing the power consumption of the variable-power compressor, for example by setting a suitable upper temperature of the refrigerant. In particular, according to the invention, blowers and variable-capacity compressors can also be matched to one another and thus a hygiene program can be optimally adapted to the type and quantity of items of laundry.

Fig. 1

zeigt einen vertikalen Schnitt durch einen Trockner gemäß einer ersten Ausführungsform, in welchem ein hierin offenbartes Verfahren durchgeführt werden kann. Andere Ausführungsformen sind denkbar.

Fig. 2

zeigt verschiedene Verläufe für die Änderung der Drehzahl eines Gebläses nach dem Beginn eines Hygieneprogrammes.

Fig. 3

zeigt verschiedene Verläufe für die Änderung der Leistungsaufnahme eines leistungsvariablen Verdichters.

Further details of the invention will become apparent from the following description of an embodiment of a dryer and a method using this dryer. Reference is made to the FIGS. 1 to 3 the attached drawing:

Fig. 1

shows a vertical section through a dryer according to a first embodiment, in which a method disclosed herein can be performed. Other embodiments are conceivable.

Fig. 2

shows different courses for the change of the speed of a fan after the start of a hygiene program.

Fig. 3

shows different curves for changing the power consumption of a variable-capacity compressor.

The Indian Fig. 1 illustrated dryer 1 according to a first embodiment has a drum 2 rotatable about a horizontal axis as a drying chamber, within which drivers 14 are mounted for movement of laundry items during a drum rotation. Process air is by means of a blower 12 through the drum 2 in a Process air circuit 3 out. After passing through the drum 2, the moist, warm process air is passed into the evaporator 8 of a heat pump 8,9,10,11, which also has a variable-speed compressor 11, a throttle 10 and a condenser 9. The in the Fig. 1 arrows shown indicate the flow direction of the air.

The vaporized in the evaporator 8 refrigerant heat pump 8,9,10,11 is passed through the variable-speed compressor 11 to the condenser 9. In the condenser 9, the refrigerant liquefies with heat being released to the process air flowing in the process air circuit 3. The then present in liquid refrigerant is passed through the throttle 10 in turn to the evaporator 8, whereby the heat pump cycle is closed. A temperature sensor S ^T _KM 6 between condenser 9 and throttle 10 measures in this embodiment, the temperature T _{K of} the refrigerant.

A mounted in the dryer 1 in the process air circuit between the drum 2 and evaporator 8 temperature sensor S ^T _PL 5 is used in the embodiment shown here for measuring the temperature T _{PL of} the process air or sufficiently long switched off dryer 1 for measuring the temperature T _R in the installation room, the in this embodiment can also be used to control the hygiene program and the dryer or its heat pump. In other embodiments of a heat pump dryer, however, can be dispensed with a measurement of the process air temperature.

When in the Fig. 1 As shown embodiment, an electric heater 13 is provided, which can be used for more rapid heating of the process air. Thus, a hygiene program can be carried out even faster. In other embodiments of the invention can be dispensed with the electric heater 13, since this leads to a higher energy consumption.

In the dryer 1 of the Fig. 1 is heated by the condenser 9 and the electric heater 13 heated air from behind, ie from the one of the filling opening occlusive access door 17 opposite side of the drum 2, passed through the perforated bottom in the drum 2, comes there with the not shown, to drying laundry items in contact and flows through the filling opening of the drum 2 to a lint filter 21 within the access door 17. Subsequently, the process air flow in the Access door 17 is deflected downwards. The process air is supplied in the process air circuit 3 to the evaporator 8, in which the warm, laden with moisture process air is cooled. The separated moisture is collected in a condensate tray 7, from where it can be removed, for example, by pumping, for example in a condensate tank, not shown here.

The drum 2 is at the in the Fig. 1 shown embodiment at the rear bottom by means of a pivot bearing and front mounted by means of a bearing plate 18, the drum 3 rests with a brim on a sliding strip 19 on the bearing plate 18 and is held at the front end. The control of the dryer 1 via a control unit 4, which can be controlled by the user via an operating unit 20.

A display device 16 allows the user of the dryer to display the execution of a hygiene program as well as details (temperature, duration) of the hygiene program. In general, the display device 16 is also used to display e.g. Operating parameters and / or an expected duration of the drying process used.

In this method, process air is repeatedly circulated through the process air circuit 3 until a hygiene program is completed and preferably a desired degree of drying of the laundry is achieved. The dryer of the Fig. 1 allows a control of the operation of the heat pump and in particular the temperature of the refrigerant accurate control and control of a hygiene program by the fan 12 and the compressor 11 are controlled so that the measures provided for the implementation of the hygiene program minimum temperature, here 70 ° C, as quickly as possible achieved and maintained for a given period of time. For this purpose, the fan speed u is reduced as desired and at the same time increases the power consumption of the variable-power compressor 11 in this embodiment.

However, care is taken that a defined maximum temperature T _max for the temperature T _{PL of} the process air is not exceeded.

In the embodiment shown here, the drum 2 and the fan 12 by a common, in the Fig. 1 not shown, power variable electric motor, here a BLDC motor, driven. Another, also in the Fig. 1 not shown, power variable electric motor is used to drive the variable-capacity compressor.

In the method according to the invention, a desired point in time for the beginning of a hygiene program is determined by evaluating sensor signals of a sensor. This may be coupled to a particular moisture of the laundry items, irrespective of a drying phase that is taking place, e.g. advantageously 10%, based on the mass of the wet laundry. Their moisture can be tracked via the evaluation of signals from the sensor.

At the in Fig. 1 shown embodiment of a suitable for carrying out the method according to the invention a dosing sensor 22 is used in the drum 2 as such a sensor, with the Leitwertsensor 22, the conductance L _w in the Fig. 1 Laundry items not shown as a function of the time t is measured. The moisture of the items of laundry and in particular the conductance of the wet items of laundry decrease particularly pronounced in the transition from the quasi-stationary to unsteady drying phase. Therefore, the beginning of a hygiene program can also be linked to this transition, whereby a speed u of the fan 12 is reduced and a power consumption p of the compressor 11 is increased in the event of a detected transition. The transition from the quasi-stationary to the transient drying phase is determined when a predetermined lower conductance L _W ^{min of} the laundry items and / or a predetermined minimum value (ΔL _W / Δt) _min for the amount of the time reduction of the conductance L _{w is} reached.

When in the Fig. 1 In the embodiment shown, a humidity sensor 23 for measuring a relative humidity F _rel of the process air leaving the drum 2 is also arranged at an outlet of the drum 2.

Fig. 2 shows different courses for the change in the speed u of fan 12 after the start of a hygiene program, this beginning can take place, for example, with the entry into the transient drying phase, as a function of the time t.

Depending on the desired sequence of the hygiene program, in particular a temperature to be achieved for the sterilization and the rate of the temperature increase, the fan speed u and power consumption p of the compressor can be adapted to the decreasing moisture of laundry items. It can be done automatically or by a user a desired reduction in the speed u of the fan. For the reduction, for example, a sudden decrease 24 of the fan speed u from a constant or nearly constant value during the quasi-stationary phase to a constant value during the transient phase is possible. But it can also be provided a gradual decrease 15 of the fan speed u, the speed u is reduced in relatively small steps towards a constant value. Moreover, for example, an asymptotic decrease 25 or a linear decrease 26 of the fan speed u is possible.

Fig. 3 shows different courses for the change in power consumption p, for example, a compressor speed of the variable-power compressor 11 after the start of a hygiene program, this beginning can take place, for example, with the entry into the transient drying phase, as a function of time t. Depending on the desired sequence of the hygiene program, in particular a temperature to be achieved for the sterilization and the rate of the temperature increase, the fan speed u and power consumption p of the compressor can be adapted to the decreasing moisture of laundry items.

It can be done automatically or by a user a desired increase in power consumption p of the compressor. For the increase, for example, a sudden increase 29 of the power consumption p from a constant or nearly constant value during the quasi-stationary phase to a constant value during the transient phase is possible. However, a stepwise increase 28 of the power consumption p may also be provided, the power consumption p being increased in comparatively small steps to a constant value. Moreover, for example, an asymptotic increase 30 or a linear increase 27 of the power consumption p is possible. The increase in the power consumption p is preferably carried out via an increase in the rotational speed of the compressor.

reference numeral

1

dryer

2

drum

3

Process air circuit

4

control unit

5

Temperature sensor S ^T _PL ; for measuring the temperature T _{PL of} the process air in the process air circuit between the drum and the evaporator

6

Temperature sensor S ^T _KM; in the heat pump circuit for measuring a temperature T _{K of} the refrigerant

7

Drain pan

8th

Evaporator

9

condenser

10

throttle

11

variable-capacity compressor

12

fan

13

Electric heater

14

Laundry pickup, driver

15

gradual decrease of the fan speed

16

optical / acoustic display device

17

access door

18

end shield

19

lubricating strip

20

operating unit

21

lint

22

Conductance sensor (in the drum)

23

Humidity sensor (to determine relative humidity)

24

sudden decrease in the fan speed

25

asymptotic decrease in blower speed

26

linear decrease in blower speed

27

gradually increasing the power consumption of the compressor, e.g. its speed

28

a sudden increase in the power consumption of the compressor, e.g. its speed

29

asymptotic increase in power consumption of the compressor, e.g. its speed

30

linear increase in power consumption of the compressor, e.g. its speed

Claims (14)

1. Method for carrying out a hygiene program in a dryer (1) comprising a drum (2) for laundry items to be dried, a process air circuit (3), in which a fan (12) for conveying process air is arranged, a control unit (4), a heat pump circuit (8, 9, 10, 11) with an evaporator (8), a condenser (9), a throttle (10) and a compressor (11), and at least one sensor (5, 6, 22, 23), wherein by means of the sensor (5, 6, 22, 23) the reduction of the moisture level Fw of the laundry items is monitored, characterised in that when a predefined lower moisture level F_W ^lowlim is reached, a rotational speed u of the fan (12) is lowered and/or a power consumption p of a variable-power compressor (11) is raised, so that a temperature required for the efficient killing of germs in the drum (2) of at least 65°C is reached.
2. Method according to claim 1, characterised in that the rotational speed u and/or the power consumption p are regulated such that the temperature T_H of the process air is maintained for a predefined period of time Δt.
3. Method according to claim 3, characterised in that the period of time Δt amounts to at least 15 min.
4. Method according to one of claims 1 to 3, characterised in that signals of the sensor (5, 6, 22, 23) are evaluated in order to be able to ascertain a transition from a quasi-stationary to a transient drying phase, and upon an ascertained transition, the rotational speed u of the fan (12) is lowered and/or the power consumption p of the variable-power compressor (11) is raised.
5. Method according to one of claims 1 to 4, characterised in that a conductance sensor (22) in the drum (2) is used as sensor (5, 6, 22, 23), wherein the conductance sensor (22) is used to measure the conductance L_W of the laundry items as a function of the time t, and the predefined lower moisture level F_W ^lowlim is reached when a predefined lower conductance L_W ^min of the laundry items and/or a predefined minimum value (ΔL_W/Δt)_min for the amount of the reduction over time of the conductance L_W is reached.
6. Method according to one of claims 1 to 5, characterised in that a temperature T_KM of a coolant is measured in the heat pump circuit (8, 9, 10, 11) by means of a temperature sensor S^T _KM (6) and the power consumption p of the variable-power compressor (11) is controlled such that the temperature T_KM lies within a range of T_KM ¹ ≤ T_KM ≤ T_KM ².
7. Method according to claim 6, characterised in that a temperature T_KM of the coolant is measured by means of the temperature sensor S^T _KM (6) arranged in the heat pump circuit (8, 9, 10, 11) and, when a maximum permitted coolant temperature T_KM ^max is reached or exceeded, the power consumption p of the power-dependent compressor (11) is decreased.
8. Method according to one of claims 1 to 7, characterised in that a shared variable-power drive motor is used for driving the fan (12) and the drum (2).
9. Method according to one of claims 1 to 8, characterised in that the variable-power compressor (11) is a compressor (11) driven by a BLDC motor.
10. Method according to one of claims 1 to 9, characterised in that the variable-power compressor (11) is a compressor with variable rotational speed, the rotational speed ω_K of which is varied as a function of the rotational speed u of the fan (12) and/or sensor signals of the sensor (5, 6, 22, 23), wherein a relationship between the rotational speed ω_K and the rotational speed u and/or the sensor signals is stored in the control unit (4).
11. Method according to claim 5 and claim 10, characterised in that the rotational speed ω_K of the compressor (11) with variable rotational speed is varied as a function of the conductance L_W ^min of the laundry items measured by the conductance sensor (22) and/or of a change over time ΔL_W/Δt of the conductance L_W, wherein use is made of a relationship between the rotational speed ω_K and the measured conductance L_W and/or the change over time ΔL_W/Δt stored in the control unit (4).
12. Method according to claim 5 and a further of claims 1 to 11, characterised in that the loading of the drum (2) with laundry items is taken into consideration by the control unit (4), in that a relationship between the conductance L_W of the power consumption p of the variable-power compressor (11) and the loading with the laundry items is stored in the control unit (4).
13. Method according to one of claims 1 to 12, characterised in that an outer temperature T_R in an installation room of the dryer (1) is measured by means of an outer temperature sensor (S^T _AR) and the rotational speed u of the fan (12) is chosen as a function of the outer temperature T_R, for which reason a relationship between the rotational speed u and the outer temperature T_R is stored in the control unit (4).
14. Dryer (1) comprising a drum (2) for laundry items to be dried, a process air circuit (3), in which a fan (12) for conveying process air is arranged, a control unit (4), a heat pump circuit (8, 9, 10, 11) with an evaporator (8), a condenser (9), a throttle (10) and a compressor (11), and at least one sensor (5, 6, 22, 23), wherein the control unit (4) is configured to perform a method, in which the reduction of the moisture level Fw of the laundry items is monitored by means of the sensor (5, 6, 22, 23), characterised in that the control unit (4) is configured in order to lower a rotational speed u of the fan (12) and/or raise a power consumption p of a variable-power compressor (11) when a predefined lower moisture level F_W ^lowlim is reached, so that a temperature required for the efficient killing of germs in the drum (2) of at least 65°C is reached.

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