CN107489008B

CN107489008B - Method for operating a condensation dryer and condensation dryer

Info

Publication number: CN107489008B
Application number: CN201710431127.2A
Authority: CN
Inventors: A·哈巴克; A·施托尔策
Original assignee: BSH Hausgeraete GmbH
Current assignee: BSH Hausgeraete GmbH
Priority date: 2016-06-10
Filing date: 2017-06-09
Publication date: 2021-04-20
Anticipated expiration: 2037-06-09
Also published as: DE102016210265A1; EP3255204B1; EP3255204A1; CN107489008A

Abstract

The invention relates to a method for operating a condensation dryer and to a condensation dryer. The condensation dryer has a process air channel in which a heat exchanger for condensing water from hot and humid process air and at least one humidity sensor are arranged, a heating device, a drum having laundry items placed therein, and a control device, the process air moving in the process air channel in a circuit by means of a blower, the drying process comprising: measuring the process air relative humidity by a humidity sensor; measuring a process air temperature by a temperature sensor; determining the absolute water load of the process air from the relative humidity while taking into account the temperature, using the relationship between the maximum water load and the temperature stored in the control device; tracking the time variation of the water load; using the time variation of the water load for determining the remaining humidity in the laundry item; comparing the residual humidity with a given residual humidity; and ending the drying process when a given residual humidity is reached or lower.

Description

Method for operating a condensation dryer and condensation dryer

Technical Field

The invention relates to a method for determining a final residual humidity in a condensation dryer and to a condensation dryer suitable for said method. The invention relates in particular to a method for operating a condensation dryer and a condensation dryer particularly suitable for carrying out the method, having a process air channel in which process air is moved in a circuit by means of a blower, a drum having laundry items placed therein, and having a control device, wherein a heat exchanger for condensing water from moist, hot process air and at least one humidity sensor are arranged in the process air channel.

Background

The drying process according to the condensation method involves evaporating moisture from the laundry items by means of hot process air and dehumidifying the process air by condensation on a heat exchanger. In this case, the cold process air is generally guided through the heating device by means of a blower during the drying process. The hot process air then enters the drum as a drying chamber containing the laundry items to be dried. Here, the hot dry process air receives moisture from the laundry items. The now moist, hot process air is then conducted further from the drum into a heat exchanger for dehumidification, for example into an air-air heat exchanger or into an evaporator of a heat pump. The hot and humid process air is cooled in this heat exchanger or evaporator, wherein the water contained in the process air is condensed and collected in a so-called condensate basin, which is generally located below the heat exchanger. On reaching a certain liquid level, the condensed water is pumped, usually by means of a pump (also referred to as "condensate pump"), into a container for intermediate storage (also referred to as "condensate container") or into a drain channel.

The drying process is generally divided into three stages, namely a heating stage, a main drying stage and a cooling stage. During the heating phase, the process air temperature rises until a predefined temperature value is reached. As the temperature increases, the process air may receive more water from the laundry items, thereby also condensing more water on the heat exchanger used for cooling. If a predefined temperature value is reached, the process air generally receives a uniform quantity of water from the laundry items in the drum. That is to say the condensation of water also remains constant. This section is referred to as the steady state or main drying stage of the drying process. The change in evaporation or condensation is steady state as long as surface water is evaporated from the laundry item. This increasingly requires more time and energy if the evaporation eventually translates into evaporation of the fine pore or capillary water in the fabric of the clothing article. The evaporation and thus the subsequent condensation in the heat exchanger therefore take place more slowly. This phase is also referred to as the non-steady-state phase, because the amount of water condensed per unit time decreases. The drying process (also called "drying program") ends with a cooling phase in which the heating means are normally switched off and in which the dried laundry is cooled.

The determination of the load of the drum over the laundry items should preferably be carried out during the drying process, in order to be able to adapt the drying process to the load, since different amounts of laundry items behave differently.

The drying process is preferably carried out such that a certain final residual humidity of the dried laundry items is reached. The degree of wetness is generally inferred from a measurement of the resistance of the article of clothing. For this purpose, different numbers of electrodes are usually arranged at different positions in the dryer. The resistance of the laundry is measured by means of these electrodes by a direct current or alternating current method. When the predetermined resistance of the laundry is the so-called off value of the heating device, in particular for the process air, the drying process is usually ended. However, these off-values are related to the load amount and the initial humidity of the laundry items (also referred to as "initial residual humidity" of wet laundry items from the washing machine) because the relative humidity of the process air must be greater for a greater load amount, for example, when the humidity is the same. It should furthermore be taken into account that, in the case of a large initial humidity, it is possible to continue for a longer time until drying of the interior of the laundry items is also achieved. In order to carry out the drying process in an improved manner, therefore, method steps for determining the starting state, that is to say in particular the load and the initial humidity of the laundry items, are often carried out. Based on such information, a matching of the turn-off limit can now be performed. So-called window methods are also known which bring a plurality of measurement parameters, such as energy, in particular the total energy consumed up to now for drying, electric power, temperature and elapsed time, into correlation with one another in order to improve the prediction accuracy.

Publication DE 102008021598 a1 describes a laundry drying appliance having a control unit for controlling the drying process. The control unit is here arranged for controlling the drying process on the basis of sensor data of the load cell.

Publication DE 102009028358 a1 describes a laundry treatment appliance for drying and/or washing laundry, having a rotatably supported drum, an electric motor for driving the drum, and a control and measuring device for the electric motor, wherein the control and measuring device senses at least one electrical parameter of the electric motor and determines the load of the drum, in particular the mass of the laundry introduced into the drum, from the sensed electrical parameter.

Publication DE 4243594C 2 describes a method for controlling a drying process of a laundry dryer comprising a drum, a heat-transferring blower, a motor, heating means, two temperature sensors and one humidity sensor, wherein the sensors are arranged between the drum and the heat-transferring blower. In the method, a temperature change and a humidity value per unit time are measured after a drying process is started after a predetermined time elapses. An average value is found from the sum of the two values and the laundry amount is determined as a small amount, a large amount, or an excessively large amount based on the average value. The further drying course is controlled corresponding to the respectively determined laundry amounts.

Publication DE 102006037239 a1 describes a laundry dryer or washer-dryer and a method for controlling the drying of wet laundry in a laundry drum of a laundry dryer or washer-dryer, in which hot air is generated and the drying process is ended taking into account at least one humidity value of the laundry to be dried or a measured value corresponding to the humidity value. For the targeted conclusion of the drying, additionally the temperature values determined during the drying of the laundry when a predefined humidity value or a measured value corresponding to this humidity value is reached or after, which correspond to the respective type of laundry and/or the respective load state of the laundry drum, are used.

Publication DE 4411958 a1 describes a domestic laundry dryer having an electronic program control and having a rotatably supported laundry drum and a ventilator for conveying drying air flowing past a heating body through the laundry drum. The temporal increase in the resistance of the drying material and the temperature difference between the drum inlet temperature and the drum outlet temperature are sensed and evaluated, wherein the type of laundry and the laundry weight of the drying material are inferred therefrom by means of an electronic device. The data acquired in this way are supplied to the program control means as control parameters for further process control of the selected drying program.

Publication DE 19918877 a1 describes a method for estimating the load and/or the drying duration before the end of a drying process in a domestic laundry dryer, in which drying process parameters relating to the humidity of the laundry and a measure for the temperature of the air flow used for drying the laundry are evaluated before or after the air flow touches the laundry. The parameter related to the humidity of the laundry in combination with the measure for the temperature of the air flow is used for estimating the load and/or the drying duration before or after the air flow touches the laundry.

Publication EP 2227585B 1 describes a laundry drying appliance and a method for operating the appliance, in which appliance the moisture content is determined from the process air discharged from the laundry drum and moisture is at least partially condensed from the process air by means of a heat exchanger, wherein the moisture determination is determined by measuring at least one temperature of the medium flowing through the heat exchanger and by analytically processing the measured temperature. The medium is either process air or coolant, and the moisture content is determined by measuring the outlet temperature of the medium at the outlet side of the heat exchanger and the inlet temperature of the medium at the inlet side of the heat exchanger.

Publication WO 2014/040904 a2 describes a condensation dryer with a load finding device and a method for operating the condensation dryer. At least one temperature sensor is arranged in the cooling medium channel and/or the process air channel and the control device is provided for determining the load of the drum through the laundry items as a function of the temporal change in the temperature measured by the at least one temperature sensor and the temporal change in the amount of condensed water. The condensation rate is determined, for example, via a water level sensor in the condensate basin or via a flow sensor or via the number of pump cycles in a certain time period.

DE 4211012C 2 describes a method for controlling a drying process as a function of the moisture content of the drying material in a dryer for laundry or other objects to be dried, which dryer is equipped with a condensation device for the discharged moisture, wherein a gradient of a state parameter occurring at the condensation device, for example one of the amount of condensation, the condensate flow or the like, is used as a measurement parameter. At the beginning of the drying process, the increased gradient value provides an indication about the amount of laundry in the laundry dryer.

Publication EP 0481561 a2 describes a method for controlling dryness in a dryer, washer-dryer or similar machine comprising a drum, means for generating a circulation through the drum, usually by hot air, for drying the laundry items in the drum, means for cooling said air, at least one tank or vessel for collecting the water removed from the laundry items by the air (which condenses on one or more of said means during the circulation), and a pump for advantageously circulating the water removed from the vessel. In order to control the dryness of the laundry items, the amount of water that has been released from the laundry items during drying thereof is measured within a predetermined time and a signal for stopping the machine is provided when the obtained measured value is less than a predetermined value.

Publication EP 0088175 A1 describes a tumble dryer with a microwave heating device for the process air. In one embodiment, one humidity sensor is disposed before the drum and one humidity sensor is disposed after the drum. The difference of the measured humidity values is used for controlling the drying process, in particular for avoiding overdrying or for adjusting a determined humidity of the laundry items.

Disclosure of Invention

Against this background, the task of the invention is to: an improved method for controlling a drying process in a condensation dryer is provided. The determination of the final residual humidity and thus the evaluation criterion for the end of the drying process should therefore preferably be improved. Furthermore, the task of the invention is: a condensation dryer suitable for use in the method is provided.

The object is achieved according to the invention by a method for operating a condensation dryer and a condensation dryer suitable for this method. A preferred embodiment of the method according to the invention corresponds to a preferred embodiment of the condensation dryer according to the invention and vice versa, even when this is not explicitly determined here.

The subject matter of the invention is thus a method for operating a condensation dryer having a process air channel in which process air is moved in a circuit by means of a blower, a heating device, a drum having laundry items placed therein, and a control device, wherein a heat exchanger for condensing water from moist hot process air and at least one humidity sensor are arranged in the process air channel, and wherein a drying process comprises the following steps:

(a) measuring the relative humidity H of the process air by means of the humidity sensor_{Relative to each other}；

(b) Measuring the temperature T of the process air by means of a temperature sensor_P；

(c) Taking into account said temperature T_PBy the relative humidity H_{Relative to each other}Determining the absolute water load L of the process air_WWherein the maximum water load L stored in the control device is used_W ^{Maximum of}And said temperature T_PThe relationship between;

(d) tracking the water load L_WA change in time;

(e) loading L with said water_wThe change in time is used to determine the residual humidity R in the item of clothing_W；

(f) Comparing the residual humidity R_WWith a predetermined residual humidity R_W ^{Given a}(ii) a And

(g) at or below the predetermined residual humidity R_W ^{Given a}The drying process is ended.

In a preferred embodiment, a predefined minimum water load L of the process air is applied in steps (e) and (f)_W ^mAs a function of the predefined residual humidity R_W ^{Given a}The metric of (2) is used.

The method according to the invention is generally started simultaneously with the introduction of the drying program. In this drying program, the heating device and the blower are generally switched on in order to guide the heated process air into the drum for drying the wet laundry items.

In one embodiment of the method according to the invention (in which only one temperature sensor and one humidity sensor are generally used), a temperature sensor and a humidity sensor are arranged in the process air channel either before or after the drum.

In an alternative embodiment of the method according to the invention, a temperature sensor and a humidity sensor are arranged in the process air channel before and after the drum, respectively, wherein then a temperature sensor and a humidity sensor are arranged in the process air channel, respectively

In the step (a), the relative humidity H is measured before the drum_{Relative to each other}As relative humidity H_{Relative to each other} ^{Front side}And measuring the relative humidity H after the drum_{Relative to each other}As relative humidity H_{After being opposite}；

In the step (b), the temperature T of the process air is measured before the drum_PAs the temperature T of the process air_P ^{Front side}And measuring the temperature T of the process air after the drum_PAs the temperature T of the process air_P ^{Rear end}；

In said step (c), taking into account said temperature T_P ^{Rear end}And T_P ^{Front side}By the relative humidity H_{Relative to each other} ^{Rear end}And H_{Relative to each other} ^{Front side}Calculating an absolute water load L of process air after the drum_W ^{Rear end}And an absolute water load L before the drum_W ^{Front side}And calculating therefrom a difference Δ L_W＝L_W ^{Rear end}–L_W ^{Front side}；

In said step (d), tracking said water load L_WDifference Δ L of_WA change in time; and

in said step (e), utilizing a water load L of said process air_WDifference Δ L of_WThe change in time is used to determine the residual humidity R in the laundry item_W。

In the method according to the invention, it is preferred that the initial humidity L is taken into account_W ^{Start of}Wherein the initial humidity L stored in the control device is utilized_W ^{Start of}And the predetermined residual humidity R_W ^{Given a}The relationship between them.

The temperature sensor and the humidity sensor used are not restricted as long as the temperature or the relative humidity of the process air can be measured by them. However, the following sensors are advantageously used: the temperature and the relative humidity of the process air can be measured simultaneously by the sensor.

In a preferred embodiment of the invention, therefore, a dual sensor is used as temperature sensor and as humidity sensor, which dual sensor is capable of simultaneously measuring the temperature T of the process air_PAnd relative humidity H_{Relative to each other}。

The influence of the air pressure is advantageously taken into account when determining the residual humidity via the absolute load of the process air by the water provided according to the invention.

In a preferred embodiment of the method according to the invention, therefore, the method according to the invention is carried out inAt least one pressure sensor is present in the process air channel, which at least one pressure sensor measures the pressure P of the process air_PAnd then using said pressure for determining said water load L_WWherein the pressure P stored in the control device is utilized_PMaximum water load L_W ^{Maximum of}And said temperature T_PThe relationship between them.

Preferably, a triple sensor is used as pressure sensor, by means of which the relative humidity H can also be measured simultaneously_{Relative to each other}And said temperature T_P。

The drying process in a condensation dryer is also influenced in particular by the air flow of the process air, since the size of the air flow also determines: how long a certain amount of air can come into contact with the wet laundry items.

In a preferred embodiment of the method according to the invention, the air flow a of the process air is therefore a flow of air_PIs regulated or measured and is taken into account for determining the predetermined residual humidity R_W ^{Given a}Wherein the air flow A stored in the control device is utilized_PAnd the residual humidity R_W ^{Given a}The relationship between them. The rotational speed or the power consumption of the process air blower can be regarded as an air flow a for the process air in this case_PIs measured. Of course, the actual air flow of the process air can also be measured by the flow measuring device and then also can be regarded as the air flow a of the process air_P。

The degree of wetness of the laundry items, that is to say the humidity or the residual humidity, varies during the drying process, since the surface water is evaporated first and the pore water or capillary water is evaporated last from the fabric of the laundry items. The variation of the moisture level during the drying process is different depending on the humidity of the laundry items and the type of fabric at the beginning of the drying process, and therefore a continuous and accurate determination of the moisture level is advantageous for laundry-conscious and energy-efficient drying of the laundry items, and for an accurate control of the final residual humidity, for example "iron drying", in respect of a predefined value.

The drying process is thereby influenced by the proportion of surface water and water present inside the laundry items, wherein the latter are removed from the laundry items only relatively slowly. Thus. The drying process is also related to the load through the laundry items.

For a predetermined residual humidity R_W ^{Given a}In any case advantageously, the load of the drum through the laundry items and/or the initial humidity of the laundry items may be taken into account.

In a preferred embodiment of the method according to the invention, the load W of the drum over the laundry items is therefore taken into account for determining the predefined residual humidity R_W ^{Given a}Wherein the load W and the residual humidity R stored in the control device are utilized_W ^{Given a}The relationship between them.

The load and/or the initial humidity can be set by the user or preferably determined by the dryer. Different approaches are possible for this. The load amount required here relates to the drying quality of the laundry items to be dried which are brought into the drum. However, the laundry items have a moisture content of, for example, about 60% with respect to the drying quality of the laundry items after the washing process and the dehydration at 1200U/min at the beginning of the drying process. In addition, different loadings appeared to be different during the drying process. Thus, for example, the drying process at full load may be extended compared to the drying process at half load. The duration of the various stages that are experienced in the drying process may also vary.

According to the present invention, the manner of determining the load W of the drum through the laundry items is not limited. Thus, the load may be determined, for example, by input from a user. However, the load of the drum is typically determined by the dryer, for example by weighing the drum and/or by evaluating the motor current and/or the electrical power of the electric drive motor. Preferably, the load is determined by evaluating the motor current and/or the electrical power of the electric drive motor. The dependency of the motor current on the load of the electric drive motor can be used for determining the load state of the drum if, for example, the power emitted at the electric drive motor remains constant. In particular, it is possible here to track the current change over a predetermined period of time, for example when the drum is running at high speed. In this case, the load can be inferred via the dependence of the electric drive motor torque on the drum load state and on the basis of the dependence of the torque on the motor current.

Of course, the method according to the invention also enables, in a preferred embodiment, the determination and consideration of the load through the laundry items and/or the initial humidity of the laundry items.

In the method according to the invention, these properties of the laundry items can advantageously be determined by determining the maximum value of the absolute water load. Here, the type of the clothing item and thus the type of the fibers can also be advantageously taken into account.

Alternatively or additionally, the absolute water load L may also be determined_WThe point in time at which the maximum of (a) occurs. In this embodiment, a time measuring device which is ubiquitous in condensation dryers is used. Furthermore, it is preferred that a relationship between the load through the items of clothing and the point in time of the maximum water load is stored in the control device.

Thus, according to the invention, a method is preferred in which the measurement is carried out in the condensation dryer until the water load L is reached_WMaximum value of (L)_W ^{Maximum of}Elapsed time period Δ t_{Maximum of}And said time period is analyzed in terms of the load W of the drum through the laundry items. In general, the control device stores a time period Δ t_{Maximum of}And the load W of the drum through the laundry items.

Furthermore, it is preferred according to the invention that the water load L is applied in terms of the load W of the drum through the laundry items_WMaximum value of (L)_W ^{Maximum of}Performing an analytical treatment, wherein different initial humidities L are utilized_W ^{Start of}The roller load W and the maximum value L stored in the control device_W ^{Maximum of}The relationship between them.

Furthermore, the subject matter of the invention is a condensation dryer with a process air channel in which process air is moved in a circuit by means of a blower, a heating device, a drum with laundry items placed in the drum, and a control device, wherein a heat exchanger for condensing water from moist hot process air and at least one humidity sensor are arranged in the process air channel, and wherein the control device is provided for carrying out a drying process, which drying process comprises the following steps:

(c) Taking into account said temperature T_PBy the relative humidity H_{Relative to each other}Determining the absolute water load L of the process air_WWherein the maximum water load L stored in the control device is utilized_W ^{Maximum of}And said temperature T_PThe relationship between;

(d) tracking the water load L_WA change in time;

According to the invention, a condensation dryer is preferred in which a temperature sensor and a humidity sensor are arranged in the process air channel before the drum and/or after the drum.

Preferably, a triple sensor is used as temperature sensor and as humidity sensor, except for the temperature T_PAnd the relative humidity H_{Relative to each other}In addition, the pressure P of the process air can also be measured by the triple sensor_P。

In general, in the condensate dryer according to the invention, the condensate pump is arranged in the condensate basin or in a condensate channel connected to the condensate basin. The condensate pan is generally connected via so-called condensate channels to a container for intermediate storage of condensate, that is to say a condensate container, or to a drain line for draining off condensate. Since the condensate basin is usually arranged in the floor module of the condensation dryer and the condensate is removed from the condensate basin against the force of gravity, a condensate pump is preferably arranged in the condensate basin or in the condensate channel in the condensation dryer according to the invention.

The condensation dryer according to the invention has a heating device, in particular an electric heating device or a gas heating device, wherein an electric heating device is preferably used. The heating device serves to heat the process air before it is introduced into the drum of the condensation dryer.

For conveying the process air, the condensation dryer furthermore has a blower in the process air duct, which blower is also referred to herein as a process air blower.

In the condensation dryer according to the invention, which is in particular designed as a circulating air dryer, at least one heat exchanger for dehumidifying the moist, hot process air is present. This is generally achieved by cooling the hot and humid process air. Heat exchangers generally utilize a cooling medium, such as cool air or a coolant, for dehumidifying the process air.

The heat exchanger is in particular an air-air heat exchanger or a heat sink of a heat pump, in particular an evaporator.

A heat pump is characterized here by two heat exchangers, namely a heat sink, in which heat is received, a heat source, in which heat is emitted, and a pump device, which can transport heat from the heat sink to the heat source in the event of a temperature change. In condensation dryers equipped with a compressor-type heat pump, the cooling of the hot process air loaded with moisture takes place substantially in a heat sink, also called evaporator, of the heat pump, where the transferred heat is used for evaporating the refrigerant circulating in the pump device configured as a circuit. The refrigerant evaporated as a result of the heating is supplied in the pump device via the compressor of the heat source, which is the liquefier for the refrigerant, to the heat pump, where the heat is released as a result of the liquefaction of the gaseous refrigerant. After the liquefier, the liquid refrigerant is then depressurized in a throttle valve of the pump device, whereby its internal pressure is relieved and finally returned to the evaporator.

In the condensation dryer according to the invention, preferably the evaporator of the air-air heat exchanger or of the heat pump is located in the process air channel. If an air-air heat exchanger is used, a cold air duct is preferably present in the air-air heat exchanger, through which relatively cold air is guided, in particular from the installation space of the dryer as a cooling medium, by means of a cold air blower.

The condensation dryer according to the invention is in particular a laundry dryer or washer-dryer. Here, the washing and drying machine is a combined appliance having a washing function for washing laundry and a drying function for drying wet laundry.

The condensation dryer advantageously has visual and/or audible display means for different states of the condensation dryer. For this purpose, a visual display device is preferably used. The display device may give information about the operation of the dryer, for example by outputting text or by illuminating differently colored light emitting diodes, for example about the absolute water load L of the laundry items_WAnd/or residual humidity R_WInformation about the load amount, the phase of the drying process, for example the heating phase, the steady-state phase, the non-steady-state phase or the remaining operating time of the drying process.

The method and the condensation dryer according to the invention have a number of advantages. The advantages of the invention are in particular: the desired residual humidity of the laundry items can be adjusted in an improved manner during the drying process, so that the end of the drying process can also be carried out in an optimized manner. In this case, in the embodiment of the invention, the laundry properties such as load and humidity can be determined and taken into account in an accurate manner by evaluating the temporal changes in the absolute water load of the process air during the drying process. The operation through the various stages of the drying process and in particular the control of the drying process to reach a predetermined residual moisture content of the laundry items is possible in embodiments of the invention for any individual loading of the drum through the laundry items. The method according to the invention and the condensation dryer according to the invention thus allow a drying process to be carried out individually, energy-efficiently and with a view to clothes, in accordance with the requirements of the user.

After the heating phase, which is related to the load and the initial residual humidity, the drying process is generally in a steady state. The relative humidity of the process air at the drum exhaust may rise to 100%. The two water loads, i.e. before and after the drum, have a maximum value. The difference of these two water loads then decreases as the drying duration increases as a measure of the water reception of the process air due to the laundry drying. The relationship between the degree of dryness of the laundry, that is to say the residual humidity and the difference in water load, can then be used as a good criterion for the shut-down of the heating device for the process air and thus for the end of the drying process. The shutdown evaluation criterion is generally dependent on the load and the process air volume flow, but is almost independent of the initial residual humidity, these influencing factors being taken into account in the embodiment of the invention.

Drawings

Further details of the invention are explained below with reference to fig. 1.

Fig. 1 shows a vertical section through a dryer configured as a condensation dryer, wherein the arrows show the flow direction of the process air. Other embodiments are contemplated.

Detailed Description

The dryer 1 shown in fig. 1 has a drum 3 which is rotatable about a horizontal axis for receiving laundry items to be dried, not shown here, and in which a driver 5 for moving the laundry items during rotation of the drum is mounted. The process air is guided in the process air duct 2 through the drum 3 by means of a process air blower 6 via an air-air heat exchanger 14 and an electric heating device 4. The air heated by the electric heater 4 is guided into the drum 3 from behind, that is to say from the side of the drum 3 opposite the door 12, through the perforated base by means of the drum inlet 19.

After being discharged from the drum 3, the process air laden with moisture flows through the filling opening of the drum 3 through a fluff screen 11 inside a door 12 closing the filling opening. The process air flow in the door 12 is then diverted downwards through the drum outlet 18 into the process air duct 2 and is guided to the air-air heat exchanger 14, through which the cold air in the cold air duct 15 can be conveyed by means of the cold air blower 16. A greater or lesser portion of the moisture received by the process air from the laundry items condenses in the air-air heat exchanger 14 due to the cooling and is collected in the condensate basin 17.

The control of the dryer 1 takes place via a control device 8, which can be adjusted by a user via an operating unit 7. The two

triple sensors

9, 10, namely the triple sensor 9 at the drum output 18 and the triple sensor 10 at the drum input 19, are connected to the control device 8. The triple sensors can each measure the relative air moisture, temperature and air pressure of the process air and can thus provide the measured values which are necessary for the method according to the invention and the preferred embodiments of the method, so that the residual humidity of the laundry items and in particular also the load of the drum 3 on the laundry items can be determined. Here, the condensation dryer also has a measurement device 20.

In the embodiment shown in fig. 1, process air blower 6 and drum 3 are driven by a drive motor 13. The drive motor 13 is a brushless direct current motor (BLDC) in this embodiment. Here, the drum is decelerated strongly, for example in a ratio of 1: 55, while the process air blower is not decelerated, but rather is driven by a drive motor in a ratio of 1: a speed ratio of 1.

The display means enable the remaining operating time of the drying process, for example ironing drying, to be displayed in terms of the remaining humidity value selected by the user, or the sought load or the remaining state of the dryer or the status of the drying process to be displayed, for example in a color-different form.

List of reference numerals

1 drier

2 Process air channel

3 roller

4 (electric) heating device

5 driving part

6 Process air blower, blower

7 operating unit

8 control device

9 triple sensor for measuring temperature, relative humidity and air pressure at the output of the drum

10 triple sensor for temperature, relative humidity and barometric pressure sensors at the drum input

11 fluff filter screen

12 door

13 a variable speed drive motor; BLDC motor in particular

14 heat exchanger; in particular air-air heat exchanger

15 cold air channel

16 cold air blower

17 condensate basin

18 drum output

19 drum input

20 time measuring device, clock

Claims

1. Method for operating a condensation dryer (1) having a process air channel (2) in which process air is moved in a circuit by means of a blower (6), a heating device (4), a drum (3) with laundry items placed therein, and a control device (8), wherein a heat exchanger (14) for condensing water from moist hot process air and at least one humidity sensor are arranged in the process air channel (2), characterized in that a drying process comprises the following steps:

(c) Taking into account said temperature T_PBy the relative humidity H_{Relative to each other}Determining the absolute water load L of the process air_WWherein the maximum water load L stored in the control device (8) is used_W ^{Maximum of}And said temperature T_PThe relationship between;

(d) tracking the water load L_WA change in time;

2. Method according to claim 1, characterized in that a predefined minimum water load L of the process air is determined in steps (e) and (f)_W ^mAs for the predetermined residual humidity R_W ^{Given a}The metric of (2) is used.

3. Method according to claim 1 or 2, characterized in that a temperature sensor and a humidity sensor are arranged in the process air channel (2) either before the drum (3) or after the drum (3).

4. Method according to claim 1 or 2, characterized in that in the process air channel, one temperature sensor and one humidity sensor are arranged before the drum (3), one temperature sensor and one humidity sensor are arranged after the drum (3), and

in the step (a), the relative humidity H is measured before the drum (3)_{Relative to each other}As relative humidity H_{Relative to each other} ^{Front side}And measuring the relative humidity H after the drum (3)_{Relative to each other}As relative humidity H_{Relative to each other} ^{Rear end}；

In the step (b), the temperature T of the process air is measured before the drum (3)_PAs the temperature T of the process air_P ^{Front side}And measuring the temperature T of the process air after the drum (3)_PAs the temperature T of the process air_P ^{Rear end}；

In said step (c), taking into account said temperature T_P ^{Rear end}And T_P ^{Front side}By the relative humidity H_{Relative to each other} ^{Rear end}And H_{Relative to each other} ^{Front side}Calculating the absolute water load L of the process air after the drum_W ^{Rear end}And an absolute water load L before the drum_W ^{Front side}And calculating therefrom a difference Δ L_W＝L_W ^{Rear end}–L_W ^{Front side}；

5. Method according to claim 1 or 2, characterized in that the initial humidity L of the laundry item is taken into account_W ^InitialWherein the initial humidity L stored in the control device is utilized_W ^InitialAnd the predetermined residual humidity R_W ^{Given a}The relationship between them.

6. Method according to claim 1 or 2, characterized in that a dual sensor is used as temperature sensor and as humidity sensor, which dual sensor is capable of measuring the temperature T of the process air simultaneously_PAnd relative humidity H_{Relative to each other}。

7. Method according to claim 1 or 2, characterized in that at least one pressure sensor is present in the process air channel (2), which at least one pressure sensor measures the pressure P of the process air_PAnd then using said pressure for determining said water load L_WWherein the pressure P stored in the control device (8) is used_PMaximum water load L_W ^{Maximum of}And said temperature T_PThe relationship between them.

8. Method according to claim 7, characterized in that a triple sensor is used as pressure sensor, by means of which the relative humidity H can also be measured simultaneously_{Relative to each other}And said temperature T_P。

9. Method according to any of claims 1-2, 8, characterized in that the air flow A of the process air_PIs regulated or measured and is taken into account for determining the predetermined residual humidity R_W ^{Given a}Wherein the air flow A stored in the control device (8) is used_PAnd the residual humidity R_W ^{Given a}The relationship between them.

10. Method according to any of claims 1-2, 8, characterized in that the load W of the drum (3) through the laundry items is taken into account for determining the predefined residual humidity R_W ^{Given a}Wherein the load W and the residual humidity R stored in the control device (8) are utilized_W ^{Given a}The relationship between them.

11. Method according to claim 10, characterized in that the measurement in the condensation dryer (1) is carried out until the water load L is reached_WMaximum value of (L)_W ^{Maximum of}Elapsed time period Δ t_{Maximum of}And said time period is analyzed in terms of the load W of the drum (3) through the laundry items.

12. Method according to claim 10, characterized in that the load L of water is applied in terms of the load W of the drum (3) through the laundry items_WMaximum value of (L)_W ^{Maximum of}Performing an analytical treatment, wherein different initial humidities L are utilized_W ^InitialAnd the load W and the maximum value L of the drum (3) stored in the control device (8)_W ^{Maximum of}The relationship between them.

13. A condensation dryer (1) having a process air channel (2) in which process air is moved in a circuit by means of a blower (6), a heating device (4), a drum (3) with laundry items placed therein, and a control device (8), wherein a heat exchanger (14) for condensing water from moist hot process air and at least one humidity sensor are arranged in the process air channel (2), characterized in that the control device (8) is provided for performing a drying process, which drying process comprises the following steps:

(d) tracking the water loadL_WA change in time;

14. A condensation dryer according to claim 13, characterized in that a temperature sensor and a humidity sensor are arranged in the process air channel (2) before the drum (3) and/or after the drum (3).

15. A condensation dryer according to claim 13 or 14, characterized in that a triple sensor is used as temperature sensor and as humidity sensor, except for the temperature T_PAnd the relative humidity H_{Relative to each other}In addition, the pressure P of the process air can also be measured by the triple sensor_P。