EP3848501A1 - Device and method for treating laundry - Google Patents

Abstract

A method for operating a drying device (1) for laundry, the drying device (1) having an air supply device (2), an air discharge device (3), a control device (6) with a target signal (S_SOLL), and i) at least one first temperature sensor (4) for detecting a first temperature sensor signal (S_TEMP_A), and at least one humidity sensor (5) for detecting a humidity sensor signal (S_FEUCHT), or ii) at least one temperature-humidity sensor for detecting a first temperature sensor signal (S_TEMP_A) and a humidity sensor signal (S_FEUCHT). The method comprises the steps of detecting the first temperature sensor signal (S_TEMP_A) and the humidity sensor signal (S_FEUCHT), determining the actual signal (S_IST) based on the first temperature sensor signal (S_TEMP_A) and the humidity sensor signal (S_FEUCHT) with the control device (6), and Compare the determined actual signal (S_IST) with the target signal (S_SOLL).

Description

TECHNICAL AREA

The present invention relates to a method for operating a drying device for laundry according to claim 1, a drying device for laundry according to claim 12, and a computer program product for a drying device according to claim 15.

STATE OF THE ART

When drying laundry in drying devices, the residual moisture to be achieved in the laundry plays a decisive role with regard to its aftertreatment. The residual moisture content is defined, for example, according to the EN 60121 standard as follows:
Target value of the residual moisture in [%] for cottons, whites and coloreds: Lack of moisture: 22 ± 5 Iron damp: 12 ± 4 Slightly dry: 3 ± 3 Cupboard dry: 0 ± 3 Extra dry: -3 ± 1 Target value of the residual moisture in [%] for easy-care laundry: Iron damp: 12 ± 4 Slightly dry: 6 ± 3 Cupboard dry: 2 ± 3 Extra dry: -1 ± 1

Compliance with this moisture content plays a decisive role in practice so that the after-treatment of the laundry in the ironer or an ironing station can be carried out without delay. For example, if the laundry is too dry, it may need to be re-moistened. This is associated with an undesirable additional expenditure of time. A control method for controlling the residual moisture when drying laundry is therefore of central importance.

Different procedures are used nowadays to record the moisture in an item such as laundry. For example, the moisture in the laundry can be determined by a resistive measurement on the laundry. However, a particular disadvantage of this method is that the laundry must touch the electrodes. In the case of tumble dryers with large drums such as those used in industry or in the case of partially loaded tumble dryers, this is not or only poorly guaranteed. As a result, the residual moisture control is inadequate. It is also the case that with residual moisture of less than 8%, the electrical resistance of the laundry is so great that precise regulation is no longer possible. Controlling the relative humidity in the exhaust air also has disadvantages. The relative humidity is not measured directly on or in the laundry, which makes the process sensitive to interference. Furthermore, the relative humidity of the exhaust air is not only dependent on the residual moisture content in the laundry, but also on many other process parameters.

DISCLOSURE OF THE INVENTION

It is therefore an object of the present invention to provide a method for operating a drying device for laundry which is improved over the known methods. In particular, a method is to be specified which is not very sensitive to interfering influences.

This object is achieved by a method according to claim 1. A method for operating a drying device for laundry is specified, the drying device comprising an air supply device, an air discharge device, a control device for performing at least one drying process, and either at least one first temperature sensor and at least one humidity sensor or at least one temperature-humidity sensor. This means that it is conceivable that at least two sensors are used, one being one of which is a temperature sensor for detecting a temperature and the other is a humidity sensor for detecting a relative humidity. Alternatively, a single sensor can be used which can detect both temperature and relative humidity. Such a combined sensor is referred to herein as a temperature-humidity sensor.

The air supply device is designed for supplying supply air to the drying device. The air removal device is designed to remove exhaust air from the drying device. The air supply device and the air discharge device are preferably lines or pipes which connect an interior of the drying device to the environment. For example, the method according to the invention can be used in an exhaust air dryer with a drum, the air supply device sucking in the air required for the drying process from a display room and conveying it into the drying device. It should be understood here, however, that the method according to the invention can be used equally not only with exhaust air dryers, but also with other known types of dryers, such as cabinet dryers, as well as with dryers with other drying processes, such as condensation dryers.

At least one setpoint signal is stored in the control device which can be assigned to a drying process that can be selected by a user. A drying process is defined in particular by a degree of drying. It is thus conceivable that the control device comprises one or more setpoint signals which correspond to one or more degrees of drying. Conceivable degrees of drying are generally known to the person skilled in the art and are referred to in the specialist field as insufficiently damp, iron dry, cupboard dry, dry, very dry, extra dry, etc. These degrees of dryness are each assigned to a corresponding residual moisture content in the laundry. It is also conceivable that the drying process is defined by the amount of laundry to be dried, by the type of laundry such as delicate laundry versus hot laundry, etc.

Furthermore, the control device is designed to determine an actual signal of the drying process during the drying process and to compare the setpoint signal with the actual signal. If the drying process that can be selected by a user corresponds or is based on a certain residual moisture content of the laundry, the setpoint signal is preferably based on a desired residual moisture content of the laundry and the actual signal is preferably based on the actual residual moisture content of the laundry.

In the case of at least two sensors, the at least one first temperature sensor is designed to detect a first temperature sensor signal, a temperature of the exhaust air being able to be determined from the first temperature sensor signal. The at least one humidity sensor is designed to detect a humidity sensor signal, a relative humidity of the exhaust air being able to be determined from the humidity sensor signal. In the case of a combined temperature and humidity sensor, the at least one temperature-humidity sensor is designed to detect a first temperature sensor signal and a humidity sensor signal, wherein a temperature of the exhaust air can be determined from the first temperature sensor signal and wherein a relative humidity of the exhaust air can be determined from the humidity sensor signal. It is important to understand that the method is analogous for the first-mentioned case of at least one temperature and one humidity sensor and for the second-mentioned case of at least one combined temperature and humidity sensor. That is, in both cases the sensors record at least one temperature sensor signal and one humidity sensor signal, a temperature of the exhaust air being determined from the temperature sensor signal and a relative humidity of the exhaust air being determined from the humidity sensor signal.

• Erfassen des ersten Temperatursensorsignals mit dem ersten Temperatursensor oder mit dem Temperatur-Feuchtigkeitssensor;
• Erfassen des Feuchtigkeitssensorsignals mit dem Feuchtigkeitssensor oder mit dem Temperatur-Feuchtigkeitssensor;
• Ermitteln des Ist-Signals basierend auf dem ersten Temperatursensorsignal und dem Feuchtigkeitssensorsignal mit der Steuervorrichtung, und
• Vergleichen des ermittelten Ist-Signals mit dem Soll-Signal.

The procedure includes the steps of:

• Detecting the first temperature sensor signal with the first temperature sensor or with the temperature-humidity sensor;
• Detecting the humidity sensor signal with the humidity sensor or with the temperature-humidity sensor;
• Determining the actual signal based on the first temperature sensor signal and the humidity sensor signal with the control device, and
• Compare the determined actual signal with the target signal.

This means that the actual signal is determined based on both the first temperature sensor signal and the humidity sensor signal. It has been shown, surprisingly, that a signal that is largely insensitive to disruptive influences can be generated by a corresponding combination of the physical parameters relative humidity and temperature of the exhaust air.

The actual signal is preferably based on a linear combination of the first temperature sensor signal and the humidity sensor signal. Or in other words the first temperature signal can be represented as S_TEMP_A and the humidity sensor signal as S_FEUCHT, a linear combination LK of the first temperature signal and the humidity signal being mathematically described by the following relationship: LK = a · S_FEUCHT + b · S_TEMP_A. At least one of the parameters a and b is preferably not equal to zero. Both parameters a and b are preferably not equal to zero.

The actual signal preferably changes linearly with the first temperature sensor signal. Additionally or alternatively, the actual signal can change linearly with the humidity sensor signal. This means that the actual signal preferably does not change quadratically or exponentially, etc. with respect to the first temperature sensor signal and / or to the humidity sensor signal.

The actual signal can be calculated as a function of the humidity sensor signal, and this function is essentially a continuous and / or monotonic function. Additionally or alternatively, the actual signal can be calculated as a function of the first temperature sensor signal, and this function is essentially a continuous and / or monotonic function.

An essentially constant and / or monotonous actual signal means here that unwanted external influences are inevitably taken into account when determining the actual signal. Examples of unwanted external influences are changing supply air conditions with regard to temperature and humidity, as well as changing air volume flows due to varying conditions in the supply air or exhaust air systems. As a result, the actual signal can have fluctuations or fluctuations, so that the actual signal does not describe a monotonic and / or continuous function but rather an essentially monotonic and / or continuous function. In the absence of such undesired external influences, however, the actual signal describes a function that is monotonically and / or continuously dependent on the humidity sensor signal and / or on the first temperature sensor signal.

Furthermore, at least one humidity parameter and at least one first temperature parameter can be stored in the control device, the humidity parameter scaling the humidity sensor signal and the first temperature parameter scaling the first temperature sensor signal in such a way that the actual signal is based on the scaled humidity sensor signal and the scaled first Temperature sensor signal describes an essentially constantly changing function. Or, in other words, the parameters a and b in the mathematical expression LK = a * S_FEUCHT + b * S_TEMP_A are preferably the humidity parameter just described and the first temperature parameter.

The actual signal can further be based on at least one first correction parameter, so that the actual signal describes an essentially continuously changing function based on the humidity sensor signal scaled with the humidity parameter, the first temperature sensor signal scaled with the first temperature parameter, and the first correction parameter.

A plurality of values for the moisture parameter a, the first temperature parameter b and the first correction parameter c are preferably stored in the control device, the respective values being dependent on the drying process, in particular the desired residual moisture level of the laundry to be dried and the type of laundry.

The actual signal preferably consists of one or more summands. Particularly preferably, the actual signal consists of at least a first addend, a second addend and a third addend, the first addend being defined by the humidity sensor signal scaled with the humidity parameter, the second addend being defined by the first temperature sensor signal scaled with the first temperature parameter , and wherein the third summand is defined by the first correction parameter.

In other words, the humidity sensor signal can be represented as S_FEUCHT, the first temperature signal as S_TEMP_A, the humidity parameter as a, the first temperature parameter as b, and the first correction parameter as c, whereby the actual signal can be mathematically calculated using the following relationship: S_lst = a · S_FEUCHT + b · S_TEMP_A + c.

Particularly preferably, the actual signal and the target signal are the actual or desired residual moisture in the laundry. In this case, this mathematical formula is used to calculate an actual signal as a function of residual moisture in the laundry, the residual moisture being calculated as a function of the moisture sensor signal and the first temperature sensor signal.

The humidity parameter is preferably negative and a ratio of the humidity parameter, the first temperature parameter and the first correction parameter to one another is preferably such that the first temperature parameter is in the range from 0.05 to 1.5 times, preferably in the range from 0.1 to 1 times, particularly preferably in the range 0.2 to 0.8 times the amount of the humidity parameter, and the first correction parameter corresponds to more than 10 times, preferably more than 50 times, particularly preferably 100 times the amount of the humidity parameter.

By means of the moisture parameter, the first temperature parameter and the first correction parameter, the method can be adapted to the selected drying process, to the type of textile and to the type of drying device. The various types of dryers mentioned at the beginning, e.g. exhaust air dryers, condensation dryers, etc., are meant under the type of drying device.

• Erfassen des zweiten Temperatursensorsignals mit dem zweiten Temperatursensor zu einem Anfangszeitpunkt und Erfassen des zweiten Temperatursensorsignals mit dem zweiten Temperatursensor zu mindestens einem gegenüber dem Anfangszeitpunkt späteren Endzeitpunkt, und
• Ermitteln eines zweiten Korrekturterms basierend auf dem zweiten Temperatursensorsignal zum Anfangszeitpunkt und dem zweiten Temperatursensorsignal zum Endzeitpunkt mit der Steuervorrichtung, wobei das Ist-Signal ebenfalls auf dem zweiten Korrekturterm basiert.

The drying device can comprise at least one second temperature sensor for detecting a second temperature sensor signal, wherein a temperature of the supply air can be determined from the second temperature sensor signal, and wherein the method preferably further comprises the steps of:

• Detecting the second temperature sensor signal with the second temperature sensor at an initial point in time and detecting the second temperature sensor signal with the second temperature sensor at at least one end point in time which is later than the start point in time, and
• Determining a second correction term based on the second temperature sensor signal at the start time and the second temperature sensor signal at the end time with the control device, the actual signal also being based on the second correction term.

The second correction term can also be understood as a summand of the actual signal. In view of the above, it would be a fourth summand, so that the actual signal preferably from the first summand including the humidity sensor signal scaled with the humidity parameter, from the second summand including the first temperature sensor signal scaled with the first temperature parameter, from the third summand comprising the first correction parameter, and the fourth summand comprising the second correction term consists.

A time interval between the start time and the end time depends on the drying device used and is typically in the range of a few minutes, for example between 1 minute and 10 minutes.

At least one third correction parameter based on an offset value of the actual signal at an actual ambient temperature that is higher than a standard ambient temperature can furthermore be stored in the control device, and the second correction term is further based on the third correction parameter. Additionally or alternatively, at least one fourth correction parameter based on thermal inertia of the drying device in the area of the air supply device can be stored in the control device, and the second correction term is further based on the fourth correction parameter. Additionally or alternatively, at least one fifth correction parameter can be stored in the control device, which is based on the standard ambient temperature, and wherein the second correction term is further based on the fifth correction parameter.

This means that the third correction parameter is used to take into account the influence of an ambient temperature and / or air humidity that deviates from the standard conditions. It has been shown that the ambient temperature and / or the humidity in a laundry, for example, which carries out a large number of drying processes in succession, change over time. This has an effect on the temperature or humidity in the drying device and consequently on the method for operating the drying device, which detects a temperature and a humidity sensor signal. The third correction parameter is dependent on the range of values of the actual signal and has, for example, a value which is approximately 2% to 10% of the range of values of the actual signal.

The fourth correction parameter is selected as a function of the inertia of the drying device and has a higher value in the case of a high inertia than in the case of a low inertia. Typical values for the fourth correction parameter are in the range from approximately 0.1 to 10, more preferably in the range from 1 to 5, particularly preferably the value of the fourth correction parameter is approximately 1.3.

The standard ambient temperature is taken into account by means of the fifth correction parameter. The fifth correction parameter preferably has a value which corresponds to the standard ambient temperature. This means that the fifth correction parameter is preferably a value in the range from 20 to 25, more preferably about 23. With such values, a standard ambient temperature in the range from 20 ° C to 25 ° C, in particular 23 ° C, can be taken into account.

The above relationships can be described mathematically as follows. The second correction term can be represented as dS, the third correction parameter as g, the fourth correction parameter as h, the fifth correction parameter as UT, the second temperature sensor signal at the start time as S_TEMP_Z_ta, and the second temperature sensor signal at the end time as S_TEMP_Z_te, where: dS = g / 10 · [S_TEMP_Z_ta - h · (S_TEMP_Z_ta - S_TEMP_Z_te) - UT].

The device can have a heating element for heating the supply air and a fan for the exhaust air, and wherein a temporal course of the drying process comprises an equilibrium phase and / or a preliminary phase and / or a post phase and / or a cooling phase. In the equilibrium phase, the fan is in operation and the heating element is out of operation. In the preliminary phase, the heating element and the fan are in operation. In the post-phase, the heating element and the fan are in operation. During the cooling phase, the heating element is out of operation and the fan is in operation. A control phase, during which the actual signal is determined and compared with the target signal, preferably takes place between the pre-phase and the post-phase.

The heating element is therefore preferably arranged in the air supply device and the fan in the air discharge device. It is further preferred that the drying device comprises a drum, as is generally known to the person skilled in the art. The air supply device then leads from the environment into the drum and the air discharge device leads out of the drum into the environment.

The equilibrium phase, the pre-phase, the post-phase and the cooling phase are preferably different time modules during which the laundry to be dried is heated or cooled to specific temperatures in the drying device. These specific temperatures preferably correspond to specified temperatures of the standard EN 60335-2-11 or EN 50570. Heating or cooling to the specific temperatures is mentioned, as mentioned obtained through a targeted switching on or off of the heating element or the fan during a certain period of time. A plurality of time periods for the respective phases are preferably stored in the control device, the respective time periods depending on the drying process, in particular on the desired residual moisture level of the laundry to be dried and on the type of laundry.

The control phase is preferably ended when the actual signal essentially corresponds to the setpoint signal, or when the actual signal exceeds the setpoint signal, or when the actual signal falls below the setpoint signal.

As mentioned earlier, the residual moisture in the laundry can be used as a criterion for the method according to the invention. In this case, the actual state of the residual moisture would be continuously determined during the drying process and compared with the target state of the residual moisture. If the actual state of the residual moisture essentially corresponds to the target state of the residual moisture, the method is ended. However, it is just as conceivable that the control phase is ended when the actual signal exceeds or falls below the target signal. Whether an overshoot or undershoot serves as a criterion depends on the parameters described above, such as the humidity parameter, the first temperature parameter and the first correction parameter. Depending on these parameters, the signal curve can be increasing or decreasing. In the case of a growing signal profile, the actual signal assumes continuously higher signal values, and the control phase is ended when the signal value of the actual signal has exceeded the signal value of the setpoint signal. In the event of a falling signal profile, the actual signal continuously assumes lower signal values, and the control phase is ended when the signal value of the actual signal has fallen below the signal value of the setpoint signal. If the method includes the aforementioned post-phase, the post-phase would begin after the control phase just described, during which a comparison between the actual state and the target state takes place.

In a further aspect, a drying device for laundry is specified, which drying device includes an air supply device, an air discharge device, a control device for carrying out at least one drying process, at least one target signal being stored in the control device which can be assigned to a drying process that can be selected by a user, and either i) at least one first temperature sensor for detecting a first temperature sensor signal and at least one humidity sensor for detecting a Humidity sensor signal, or ii) comprises at least one temperature-humidity sensor for detecting a first temperature sensor signal and a humidity sensor signal. The air supply device is designed for supplying supply air to the drying device. The air removal device is designed to remove exhaust air from the drying device. A temperature of the exhaust air can be determined from the first temperature sensor signal. A relative humidity of the exhaust air can be determined from the humidity sensor signal. The control device is designed to determine the actual signal based on the first temperature sensor signal and the humidity sensor signal and to compare the actual signal with the setpoint signal.

That is to say, the drying device according to this further aspect preferably corresponds to a drying device as it was explained in connection with the previously described method for operating a drying device for laundry. All statements made for this last-mentioned drying device therefore apply equally to the drying device according to the further aspect, and vice versa.

If the drying device has at least one first temperature sensor and one humidity sensor, the first temperature sensor and / or the humidity sensor is preferably arranged in the air discharge device. If it is a combined temperature-humidity sensor, this temperature-humidity sensor is preferably arranged in the air discharge device.

The drying device can further detect at least one second temperature sensor for detecting a second temperature sensor signal, the second temperature sensor being arranged in the air supply device. Based on this second temperature sensor signal, the second correction term is preferably determined as explained above.

In a further aspect, a computer program product for a drying device as described above is specified, the computer program product comprising instructions which, when the computer program product is executed by a processor, initiate the method as described above.

The computer program product can be stored in a storage medium, in particular on a non-volatile data carrier.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1

zeigt eine Schnittansicht durch eine Trocknungsvorrichtung zur Durchführung eines Trocknungsverfahrens;

Fig. 2

zeigt das durch das Trocknungsverfahren ermittelte Ist-Signal als Funktion einer Restfeuchte der Wäsche für unterschiedliche Beladungsmengen;

Fig. 3

zeigt einen Temperaturverlauf der Abluft als Funktion der Zeit in einem Trocknungsverfahren;

Fig. 4

zeigt ein Blockschaltbild betreffend die Ermittlung des Ist-Signals und der Vergleich des Ist-Signals mit einem Soll-Signal in einem Trocknungsverfahren;

Fig. 5

zeigt einen Verlauf des Ist-Signals als Funktion einer Restfeuchte der zu trocknenden Wäsche für unterschiedliche Umgebungstemperaturen.

Preferred embodiments of the invention are described below with reference to the drawings, which are only used for explanation and are not to be interpreted as restrictive. In the drawings show:

Fig. 1

shows a sectional view through a drying device for carrying out a drying process;

Fig. 2

shows the actual signal determined by the drying process as a function of residual moisture in the laundry for different loads;

Fig. 3

shows a temperature profile of the exhaust air as a function of time in a drying process;

Fig. 4

shows a block diagram relating to the determination of the actual signal and the comparison of the actual signal with a target signal in a drying process;

Fig. 5

shows a course of the actual signal as a function of residual moisture in the laundry to be dried for different ambient temperatures.

DESCRIPTION OF PREFERRED EMBODIMENTS

In Figure 1 a drying device 1 for laundry is shown, which has a housing 11 with a drum 10 arranged therein, an air supply device 2 for supplying air from an environment into the drying device 1, in particular into the drum 10, and an air discharge device 3 for discharging exhaust air the drying device 1, in particular out of the drum 10 into the environment. A control device 6, a heating element 8 for heating the supply air, a fan 9 for the exhaust air, a first temperature sensor 4, a second temperature sensor 7 and a humidity sensor 5 are also arranged in the housing 11. In particular, the heating element 8 is attached in the air supply device 2 and the fan 9 is located in the air discharge device 3. In the present example, the first temperature sensor 4 and the humidity sensor 5 are designed as separate sensors and are located in the air discharge device 3 trained sensors could just as well be a combined temperature-humidity sensor be used. The second temperature sensor 7 is located in the air supply device 2. Both the first temperature sensor 4, the humidity sensor 5 and the second temperature sensor 7 are connected to the control device 6 and designed to transmit their respective measured values to the control device 6. In particular, the first temperature sensor 4 is designed to detect a first temperature sensor signal S_TEMP_A, wherein a temperature of the exhaust air TA can be determined from the first temperature sensor signal S_TEMP_A, and the humidity sensor 5 is designed to detect a humidity sensor signal S_FEUCHT, with a relative humidity of the exhaust air FA from the Moisture sensor signal S_FEUCHT can be determined. The first temperature sensor signal S_TEMP_A and the humidity sensor signal S_FEUCHT are then transmitted to the control device 6. The control device 6 is designed to carry out at least one drying process. In the present example, the drying process is defined by the degree of dryness of the laundry to be dried. For this purpose, one or more target signals S_SOLL are stored in the control device, which correspond to one or more degrees of drying. Furthermore, the control device has a processor (not shown) and a computer program product (not shown) comprising commands which initiate a drying process when the computer program product is executed by the processor.

The drying method comprises the steps of i) detecting the first temperature sensor signal S_TEMP_A with the first temperature sensor 4, ii) detecting the humidity sensor signal S_FEUCHT with the humidity sensor 5, iii) determining the actual signal S_IST based on the first temperature sensor signal S_TEMP_A and the humidity sensor signal S_FEUCHT with the Control device 6, and iv) comparing the determined actual signal S_IST with the target signal S_SOLL. The sequence of steps i) and ii) can also be reversed, that is to say first the humidity sensor signal S_FEUCHT can be detected with the humidity sensor 5 and then the first temperature sensor signal S_TEMP_A with the first temperature sensor 4, or steps i) and ii) can be detected simultaneously respectively. It is also the case that steps i) to iv) are carried out several times. This means that the actual signal is preferably continuously determined at regular time intervals and compared with the setpoint signal stored in the control device 6. This phase can be referred to as the control phase PR, which is preferably ended when the actual signal S_IST essentially corresponds to the setpoint signal S_SOLL.

The actual signal S_IST is based both on the first temperature sensor signal S_TEMP_A and on the humidity sensor signal S_FEUCHT. The inventors have found out that an actual signal that is largely insensitive to interfering influences can be generated by a corresponding combination of the physical parameters relative humidity of the exhaust air and temperature of the exhaust air. In a first embodiment, an actual signal S_IST was calculated by the control device 6 in the control phase PR, which is based on a linear combination of the first temperature sensor signal S_TEMP_A and the humidity sensor signal S_FEUCHT.

Furthermore, one or more humidity parameters a, one or more first temperature parameters b, and one or more first correction parameters c are stored in the control device 6. These parameters are used together with the first temperature sensor signal S_TEMPA_A or S_FEUCHT measured by the first temperature sensor 4 and the humidity sensor 5 to calculate the actual signal, the humidity parameter or parameters a being the humidity sensor signal S_FEUCHT measured by the humidity sensor 5 and the first temperature parameter or parameters b das Scale the temperature sensor signal S_TEMP_A measured by the first temperature sensor 4, and the first correction parameter or parameters c are also taken into account as a constant offset value in order to scale the actual signal S_IST to the range specified by the control device 6.

As mentioned earlier, different values for the humidity parameter a, the first temperature parameter b, and the first correction parameter c can be stored in the control device 6, the control device 6 each having a specific value for a specific drying process selected by the user to calculate the actual value Signal used. For illustration purposes, in Figure 2 the course of the digitized actual signal is shown as a function of the residual moisture of the laundry to be dried for different loads of the laundry to be dried. The digitized actual signal was continuously calculated using the formula S_Ist = a · S_FEUCHT + b · S_TEMP_A + c, where a = -1, b = 0.6, and c = 57, which here corresponds to a cotton drying process. The load quantities correspond to a load with the nominal weight of 25% (dashed line), 50% (dash-dot line) and 100% (solid line). How good from the in Figure 2 As can be seen in the graphic shown, the actual signal describes itself from a residual moisture level of less than about 50% essentially continuously changing as well as monotonically increasing function. Essentially continuous or monotonic here means that there are jumps between the individual function values in the event of a sufficiently small change on the X-axis. These are due to the discrete signal calculation and any external influences. In the course of development, various interfering influences on the accuracy of the control were identified and investigated. As from the in Figure 2 As can be seen in the graphic shown, for example, the different loading quantities lead to pronounced differences in the signal curve of the actual signal. There are also clear signal differences for the residual moisture of around 50% and higher. This is due to the fact that a tumble dryer is operated continuously in practice and the start temperatures change, which has an influence on the residual moisture measurement and control at high residual moisture levels.

It was recognized that these unwanted effects can be largely compensated for by using suitable time modules. These time modules are connected upstream and downstream in the phase with controlled operation according to the signal, i.e. the control phase PR. As already mentioned earlier, the control phase PR of the drying process can include further phases. For example, the time course of the drying process can include an equilibrium phase PG, a preliminary phase PV, a post phase PN and a cooling phase PA. These different phases are based on a theoretical signal in Figure 3 discussed. This theoretical signal shows the expected temperature profile of the exhaust air as a function of time in a drying process according to the invention.

In terms of time, the drying process begins with the equilibrium phase PG, with the fan 9 in operation and the heating element 8 in operation. With this equilibrium phase PG, a discrepancy between the actual signal and the target signal can be weakened in the case of high residual moisture. As a result, the signal at the start of the drying process, i.e. before the control phase PR, can be stabilized at a usable level. Subsequent to the equilibrium phase PG is the preliminary phase PV, during which the heating element 8 and the fan 9 are in operation. The preliminary phase PV is followed by the control phase PR described above, during which an actual value is continuously compared with the setpoint value. The control phase PR is followed by the post-phase PN, the heating element 8 and the fan 9 being in operation. The last phase is formed by the cooling phase PA, which temporally follows the post-phase PN, and during which the heating element 8 is out of operation and the fan 9 in Are operating.

In some laundries the temperatures and humidity levels are significantly higher than in the laboratory. Since the parameters for drying programs are determined under laboratory conditions, there may be deviations in practice. It has been shown that these deviations between the practical conditions and the laboratory conditions correspond to an essentially constant offset value over the entire residual moisture range. To compensate for this effect, the temperature at the drum inlet is monitored during the equilibrium phase PG. This temperature monitoring takes place here by means of the second temperature sensor 7, which determines the temperature of the supply air and transmits this to the control device 6 in the form of a second temperature sensor signal S_TEMP_Z. Specifically, the second temperature sensor 7 detects a second temperature sensor signal S_TEMP_Z at a starting point in time ta and at at least one further end point in time te that is later than the start point in time ta. The control device 6 then determines a second correction term dS based on the second temperature sensor signal S_TEMP_Z at the start time ta and the second temperature sensor signal S_TEMP_Z at the end time te, and takes this second correction term into account when determining the actual signal S_IST.

A third correction parameter g based on the just described offset value of the actual signal S_IST at an actual ambient temperature under practical conditions that is increased compared to a standard ambient temperature under laboratory conditions, and a fourth correction parameter h based on thermal inertia of the drying device 1 in the area of the air supply device 2 are also in the control device 6 , as well as a fifth correction parameter UT, which is based on the standard ambient temperature or laboratory temperature, is saved. The second correction term dS is further based on the third correction parameter g, on the fourth correction parameter h, and on the fifth correction parameter UT.

wobei $$\mathrm{dS}=\mathrm{g}/\mathrm{10}\cdot \left[\mathrm{S\_TEMP\_Z\_ta}-\mathrm{h}\cdot \left(\mathrm{S\_TEMP\_Z\_ta}-\mathrm{S\_TEMP\_Z\_te}\right)-\mathrm{UT}\right]\mathrm{.}$$

In other words, in order to take into account the above-mentioned influences when calculating the actual signal, it is calculated by the control device 6 as follows: $$\mathrm{S\; IS}=\mathrm{a}\cdot \mathrm{S\_FEUMT}+\mathrm{b}\cdot \mathrm{S\_TEMP\_A}+\mathrm{c}+\mathrm{dS},$$

in which $$\mathrm{dS}=\mathrm{G}/\mathrm{10}\cdot \left[\mathrm{S\_TEMP\_Z\_ta}-\mathrm{H}\cdot \left(\mathrm{S\_TEMP\_Z\_ta}-\mathrm{S\_TEMP\_Z\_te}\right)-\mathrm{UT}\right]\mathrm{.}$$

In Figure 4 the determination of this actual signal S_IST and the comparison of the actual signal with the target signal S_SOLL illustrated by means of a block diagram. This means that different values for the parameters humidity parameter a, first temperature parameter b, first correction parameter c, third correction parameter g, fourth correction parameter h, and fifth correction parameter UT are stored in control device 6, these parameters continuously with those of control device 6 in accordance with the above context supplied sensor measured values S_FEUCHT, i.e. the humidity sensor signal, S_TEMP_A, i.e. the first temperature sensor signal, S_TEMP_Z_ta, i.e. the second temperature sensor signal at an initial point in time, S_TEMP_Z_te, i.e. the second temperature sensor signal at an end point in time.

The compensation achieved in this way is calculated using the in Figure 5 illustrated graphic clarifies. It shows the time course of the actual signal as a function of the residual moisture in the laundry for a load of 100% in each case, with the actual signal being determined for an ambient temperature of 23 ° C (solid line) and for an ambient temperature of 25 ° C (dashed line) took place. REFERENCE LIST 1 Drying device b Temperature parameters 2 Air supply device c first correction parameter 3 Air evacuation device dS second correction term 4th Temperature sensor 9 third correction parameter 5 Humidity sensor H fourth correction parameter 6th Control device UT fifth correction parameter 7th Temperature sensor PG Equilibrium phase 8th Heating element PV Preliminary phase 9 fan PN Post phase 10 drum PA Cooling phase 11 casing PR Control phase S_SOLL Target signal ta Starting time S IS Actual signal te End time S_FEUMT Humidity sensor signal FA relative humidity S_TEMP_A Temperature sensor signal the exhaust air S_TEMP_Z Temperature sensor signal TA Exhaust air temperature a Humidity parameters

Claims (15)

A method for operating a drying device (1) for laundry, the drying device (1) comprising: - An air supply device (2) for supplying supply air to the drying device (1); - An air discharge device (3) for discharging exhaust air from the drying device (1); - A control device (6) for performing at least one drying process, at least one target signal (S_SOLL) being stored in the control device (6), which can be assigned to a drying process that can be selected by a user, and the control device (6) is designed for this purpose is to determine an actual signal (S_IST) of the drying process during the drying process and to compare the target signal (S_SOLL) with the actual signal (S_IST); and i) at least one first temperature sensor (4) for detecting a first temperature sensor signal (S_TEMP_A), wherein a temperature of the exhaust air (TA) can be determined from the first temperature sensor signal (S_TEMP_A), and
at least one humidity sensor (5) for detecting a humidity sensor signal (S_FEUCHT), wherein a relative humidity of the exhaust air (FA) can be determined from the humidity sensor signal (S_FEUCHT), or ii) at least one temperature / humidity sensor for detecting a first temperature sensor signal (S_TEMP_A) and a humidity sensor signal (S_FEUCHT), wherein a temperature of the exhaust air (TA) can be determined from the first temperature sensor signal (S_TEMP_A) and wherein a relative humidity of the exhaust air (FA) can be determined the humidity sensor signal (S_FEUCHT) can be determined; the method comprising the steps of: - Detecting the first temperature sensor signal (S_TEMP_A) with the first temperature sensor (4) or with the temperature-humidity sensor; - Detecting the humidity sensor signal (S_FEUCHT) with the humidity sensor (5) or with the temperature-humidity sensor; - Determination of the actual signal (S_IST) based on the first temperature sensor signal (S_TEMP_A) and the humidity sensor signal (S_FEUCHT) with the control device (6), and - Compare the determined actual signal (S_IST) with the target signal (S_SOLL). Method according to claim 1, wherein the actual signal (S_IST) is based on a linear combination of the first temperature sensor signal (S_TEMP_A) and the humidity sensor signal (S_FEUCHT). Method according to one of the preceding claims, wherein the actual signal (S_IST) changes linearly with the first temperature sensor signal (S_TEMP_A), and / or
whereby the actual signal (S_IST) changes linearly with the humidity sensor signal (S_FEUCHT). Method according to one of the preceding claims, wherein the actual signal (S_IST) is calculated as a function of the humidity sensor signal (S_FEUCHT) and / or the first temperature sensor signal (S_TEMP_A), and this function is essentially a continuous and / or monotonic function. Method according to one of the preceding claims, wherein furthermore at least one humidity parameter (a) and at least one first temperature parameter (b) are stored in the control device (6), the humidity parameter (a) the humidity sensor signal (S_FEUCHT) and the first temperature parameter (b) scale the first temperature sensor signal (S_TEMP_A) in such a way that the actual signal (S_IST) describes an essentially continuously changing function based on the scaled moisture sensor signal (S_FEUCHT) and the scaled first temperature sensor signal (S_TEMP_A). Method according to claim 5, wherein the actual signal (S_IST) is further based on at least one first correction parameter (c), so that the actual signal (S_IST) is based on the humidity sensor signal (S_FEUCHT) scaled with the humidity parameter (a), the with the first temperature sensor signal (S_TEMP_A) scaled to the first temperature parameter (b), and the first correction parameter (c) describes an essentially continuously changing function. The method according to claim 6, wherein the moisture parameter (a) is negative and a ratio of the humidity parameter (a), the first temperature parameter (b) and the first correction parameter (c) to one another is such that the first temperature parameter (b) is in the range of 0.05 to 1.5 times, preferably in the range of 0.1 to 1 times, particularly preferably in the range of 0.2 to 0.8 times the amount of the moisture parameter (a), and the first correction parameter (c) is more than 10 times, preferably more than 50 times, particularly preferably 100 times corresponds to the amount of the moisture parameter (a). Method according to one of the preceding claims, wherein the drying device (1) comprises at least one second temperature sensor (7) for detecting a second temperature sensor signal (S_TEMP_Z), wherein a temperature of the supply air can be determined from the second temperature sensor signal (S_TEMP_Z), and wherein the method continues which includes the steps of: - Detecting the second temperature sensor signal (S_TEMP_Z) with the second temperature sensor (7) at a starting time (ta) and detecting the second temperature sensor signal (S_TEMP_Z) with the second temperature sensor (7) at at least one end time (te) later than the starting time (ta) , and - Determination of a second correction term (dS) based on the second temperature sensor signal (S_TEMP_Z) at the start time (ta) and the second temperature sensor signal (S_TEMP_Z) at the end time (te) with the control device (6), the actual signal (S_IST) also on based on the second correction term (dS). Method according to claim 8, wherein at least one third correction parameter (g) based on an offset value of the actual signal (S_IST) is stored in the control device (6) at an actual ambient temperature that is higher than a standard ambient temperature, and wherein the second correction term (dS) is further based on the third correction parameter (g), and / or
wherein at least one fourth correction parameter (h) based on a thermal inertia of the drying device (1) in the area of the air supply device (2) is stored in the control device (6), and wherein the second correction term (dS) is further based on the fourth correction parameter (h) based, and / or
wherein in the control device (6) further at least one fifth Correction parameter (UT) is stored, which is based on the standard ambient temperature, and wherein the second correction term (dS) is further based on the fifth correction parameter (UT). Method according to one of the preceding claims, wherein the device has a heating element (8) for heating the supply air and a fan (9) for the exhaust air, and wherein a temporal course of the drying process is an equilibrium phase (PG) and / or a preliminary phase (PV ) and / or a post phase (PN) and / or a cooling phase (PA),
wherein in the equilibrium phase (PG) the fan (9) is in operation and the heating element (8) is out of operation,
wherein in the preliminary phase (PV) the heating element (8) and the fan (9) are in operation,
wherein in the post-phase (PN) the heating element (8) and the fan (9) are in operation,
wherein in the cooling phase (PA) the heating element (8) is out of operation and the fan (9) is in operation, and
wherein a control phase (PR), during which the actual signal (S_IST) is determined and compared with the target signal (S_SOLL), preferably takes place between the pre-phase (PV) and the post-phase (PN). Method according to claim 10, wherein the control phase (PR) is ended when the actual signal (S_IST) essentially corresponds to the target signal (S_SOLL), or when the actual signal (S_IST) exceeds the target signal (S_SOLL) , or if the actual signal (S_IST) falls below the target signal (S_SOLL). Drying device (1) for laundry comprising: - An air supply device (2) for supplying supply air to the drying device (1); - An air discharge device (3) for discharging exhaust air from the drying device (1); - A control device (6) for performing at least one drying process, at least one target signal (S_SOLL) being stored in the control device (6) which can be assigned to a drying process that can be selected by a user; and i) at least one first temperature sensor (4) for detecting a first one Temperature sensor signal (S_TEMP_A), wherein a temperature of the exhaust air can be determined from the first temperature sensor signal (S_TEMP_A), and
at least one humidity sensor (5) for detecting a humidity sensor signal (S_FEUCHT), wherein a relative humidity of the exhaust air can be determined from the humidity sensor signal (S_FEUCHT), or ii) at least one temperature / humidity sensor for detecting a first temperature sensor signal (S_TEMP_A) and a humidity sensor signal (S_FEUCHT), wherein a temperature of the exhaust air (TA) can be determined from the first temperature sensor signal (S_TEMP_A) and wherein a relative humidity of the exhaust air (FA) can be determined the humidity sensor signal (S_FEUCHT) can be determined;
characterized in that the control device (6) is designed to determine the actual signal (S_IST) based on the first temperature sensor signal (S_TEMP_A) and the humidity sensor signal (S_FEUCHT) and to determine the actual signal (S_IST) with the target signal ( S_SOLL) to be compared. Drying device (1) according to claim 12, wherein i) the first temperature sensor (4) and / or the humidity sensor (5) or ii) the temperature-humidity sensor are arranged in the air discharge device (3). Drying device (1) according to claim 12 or 13, further comprising at least one second temperature sensor (7) for detecting a second temperature sensor signal (S_TEMP_Z), the second temperature sensor (7) being arranged in the air supply device (2). Computer program product for a drying device (1) according to one of Claims 12 to 14, comprising instructions which, when the computer program product is executed by a processor, initiate the method according to one of Claims 1 to 11.

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