Dryer and method for adjusting a drying temperature for a dryer

Abstract

The invention relates to a method for setting a drying temperature for a drying unit. The method comprises a step of reading a temperature signal, representing a current process air temperature and / or a current cooling and / or refrigerant temperature, and / or a laundry temperature signal, representing a current laundry temperature, via an interface to a sensor device (105) of the drying unit (100). The method further comprises a step of controlling a blower unit (110) using a control signal, wherein in the control step the process air temperature and / or the cooling and / or refrigerant temperature is controlled using the temperature signal such that the laundry temperature does not exceed a predetermined setpoint in order to set the drying temperature.

Description

[0001] The invention relates to a method for setting a drying temperature for a drying device and to a drying device.

[0002] The current trend in washing temperatures is toward lower temperatures. Even the standard specifies a 40°C program. A heat-pump dryer currently reaches a maximum wash temperature of 53 to 57°C, significantly higher than the washing temperatures.

[0003] DE 44 09 607 A1 describes a condensation tumble dryer with a heat pump.

[0004] DE 10 2012 105 829 A1 discloses an exhaust air dryer with a fan and a heating element for generating and heating the process air. The fan and heating element are controlled depending on the required operating conditions.

[0005] DE 10 2018 213 108 A1 discloses a tumble dryer with a fan and a heating element, whereby the fan and thus the intensity of the process air flow can be regulated.

[0006] EP 3 425 109 A1 discloses a method for performing a heat pump drying process for a drying device with a heat pump and a fan for generating process air. The activity of the compressor is controlled depending on several parameters.

[0007] WO 2013 / 050262 A1 discloses a heat-pump tumble dryer with a cooling fan that cools a compressor and a control unit that controls a drying process. A temperature sensor is arranged in an air duct. The control unit does not switch on the cooling fan if a temperature value measured by the first temperature sensor in the air duct is lower than a predetermined limit temperature value. The control unit switches on the cooling fan if the temperature value measured in the air duct is higher than the limit temperature value.

[0008] The approach presented here aims to create an improved method for setting a drying temperature for a drying device as well as an improved drying device.

[0009] According to the invention, this object is achieved by a method for setting a drying temperature for a drying device and by a drying device having the features of the main claims. Advantageous embodiments and further developments of the invention emerge from the respective subclaims below.

[0010] The advantages achievable with the invention are the reduction of power loss and the improvement of customer comfort, since textiles or laundry can advantageously be dried in the drying device without any problems.

[0011] A method for setting a drying temperature for a drying device is presented. The method comprises a reading step and a control step. In the reading step, a temperature signal representing a current process air temperature is read via an interface to a sensor device of the drying device. In the control step, a fan unit is controlled using a control signal. The cooling and additionally or alternatively refrigerant temperatures are controlled using the temperature signal such that the laundry temperature does not exceed a predetermined setpoint in order to adjust the process air temperature.

[0012] The method can be carried out, for example, in a drying appliance, such as a washer-dryer. The sensor device can comprise one or more sensors, such as NTC sensors. NTC stands for "Negative Temperature Coefficient," so the NTC sensor can be described as a thermistor. The blower unit can, for example, be designed as a fan and can be additionally or alternatively connected to a compressor of the drying appliance.

[0013] According to one embodiment, in the control step, the fan unit can be controlled using the control signal, wherein the predetermined setpoint can represent a program temperature selected in a washing program and additionally or alternatively a measured temperature. This means that the drying appliance can, for example, comprise a washing function. The program temperature of the corresponding washing program can advantageously be used as the setpoint for a drying process. Shrinkage or shrinkage of the laundry due to an excessively high drying temperature can advantageously be avoided, for example. Additionally or alternatively, the sensor can, for example, be designed as a thermometer, which advantageously measures current temperatures.

[0014] In the control step, the process air temperature and, additionally or alternatively, the cooling and, additionally or alternatively, the refrigerant temperature can also be controlled using a control algorithm with an inner control loop and / or an outer control loop to control the blower unit. This advantageously allows the blower unit to be cascaded, enabling finely tuned control of the drying unit.

[0015] According to one embodiment, in the control step, the process air temperature can represent a reference variable of the outer control loop, and the cooling and additionally or alternatively refrigerant temperature can represent a further reference variable of the inner control loop. Alternatively, the cooling and additionally or alternatively refrigerant temperature can represent the reference variable of the outer control loop, and the process air temperature can represent the further reference variable of the inner control loop. The control signal can thereby represent a control variable for controlling the blower unit. Advantageously, cascaded adjustment of the blower unit is also possible here, enabling finely tuned control of the drying device.

[0016] Furthermore, a drying device is presented which has a sensor device for detecting a current process air temperature, a current cooling and additionally or alternatively refrigerant temperature and a current laundry temperature.

[0017] Furthermore, the drying device has a fan unit for regulating the process air temperature and additionally or alternatively the cooling and additionally or alternatively the refrigerant temperature as well as a control unit in a variant mentioned here.

[0018] In the drying device, a process is carried out in a variant specified here and is thus advantageously implemented in a power- or energy-saving manner. Advantageously, already installed components, such as sensors, can be at least partially used for this purpose, thus saving manufacturing costs. Advantageously, the drying device can also be used both for private purposes and in conjunction with a commercial or professional device, for example, a medical device such as a cleaning or disinfection device, a small sterilizer, a large-capacity disinfector, or a container washing system.

[0019] According to one embodiment, the drying device can be designed as a heat pump dryer.

[0020] An embodiment of the invention is shown purely schematically in the drawings and is described in more detail below. It shows Figure 1 shows a schematic representation of a drying device according to an embodiment, wherein a control circuit for controlling the blower unit is also shown to explain the functioning of the approach presented here; Figure 2 shows a schematic representation of a drying device according to an embodiment, wherein a control circuit for controlling the blower unit is also shown to explain the functioning of the approach presented here; Figure 3 shows a schematic representation of a drying device according to an embodiment, wherein a control circuit for controlling the blower unit is also shown to explain the functioning of the approach presented here; Figure 4 shows a flow diagram of a method according to an embodiment for setting a drying temperature for a drying device; and Figure 5 shows a block diagram of a control unit according to an embodiment for a drying device.

[0021] Figure 1shows a schematic representation of a drying device 100 according to an exemplary embodiment. The drying device 100 is implemented, for example, as a heat pump dryer or, for example, as a washer-dryer. The drying device 100 has a sensor device 105 that is designed to detect a current process air temperature, a current cooling and / or refrigerant temperature, and a current laundry temperature. Furthermore, the drying device 100 has a fan unit 110 that is designed to regulate the cooling and / or refrigerant temperature. For this purpose, the drying device 100 has a control unit 115. The control unit 115 is designed to control the fan unit 110 and to carry out a method for setting a process air temperature for the drying device 100, as described in more detail in one of the following figures.

[0022] To clarify this, according to this embodiment in Figure 1a control system according to the control circuit diagram 116 is integrated. The control circuit diagram 116 represents a functional connection between the sensor device 105 and the blower unit 110. According to this exemplary embodiment, the current process air temperature is read in as a reference variable 117 using a temperature signal, and the blower unit 110 is controlled using a controlled variable 118, for example, by a controller 121. The process air temperature is controlled such that a laundry temperature does not exceed a predetermined setpoint. In this way, according to this exemplary embodiment, a drying temperature of laundry 119 to be dried is set. This means that within such a control process, for example, the reference variable 117 is compared with the setpoint in order to use a deviation, for example, to control the blower unit 110 accordingly using the controlled variable 118.

[0023] According to this exemplary embodiment, the sensor device 105 comprises at least one detection sensor 120, in particular two detection sensors 120, each of which is optionally implemented as an NTC sensor. One of the detection sensors 120 is arranged, for example, in a process air duct 125 of the drying device 100 in order to detect the process air temperature, which is discharged, for example, from a laundry drum 130 for receiving laundry 119 of the drying device 100 and, according to this exemplary embodiment, represents the reference variable 117. In order to detect the cooling and / or refrigerant temperature, one of the detection sensors 120, according to this exemplary embodiment, is arranged adjacent to a compressor 135 of the drying device 100. The compressor 135 is designed, for example, to extract heat from a cooling and / or refrigerant and thereby compress it.According to this embodiment, the drying device 100 further comprises a compressor drive 137 which is designed to drive the compressor 135.

[0024] According to this exemplary embodiment, the process air flows from the laundry drum 135 through the process air duct 125. The process air optionally passes through one or more process air filters 140 before reaching an evaporator 145 of the drying device 100. According to this exemplary embodiment, the evaporator 145 is connected to the compressor 135 and to a valve 150. The drying device 100 further comprises a condenser 155, which, according to this exemplary embodiment, is arranged parallel to the evaporator 145. According to this exemplary embodiment, one of the detection sensors 120 is arranged between the compressor 135 and the condenser 155. The condenser 155 is optionally designed, for example, to bring the process air to a specific temperature.Furthermore, the process air is conveyed from the condenser 155 by means of a process air blower 160 in the direction of the laundry drum 130, which is connected, for example, to a drive 165 for driving the laundry drum 130.

[0025] In other words, a possibility is presented for implementing a drying program for the drying appliance 100, such as a heat-pump dryer, with a specified temperature, for example, 40°C, since currently, for example, the heat-pump dryer dries laundry at approximately 52-57°C, a condenser dryer at 80°C, and a washer-dryer at 85°C. In short, a laundry temperature control is presented.

[0026] With the approach presented here, the maximum laundry temperature reached, for example, in a washing process is not exceeded in the drying process. This means, for example, that everything washed at 40°C can be safely dried in the drying device 100. According to this exemplary embodiment, the existing sensor system, referred to here as sensor device 105, is used to indirectly determine the laundry temperature, since direct measurement of the laundry temperature is not possible. Implicit system knowledge is used for this purpose. This means, for example, that the laundry temperature roughly corresponds to the drum outlet temperature plus approximately 2°C. According to this exemplary embodiment, the drum outlet temperature is measured upstream of the heat exchanger using an NTC sensor, referred to here as detection sensor 120, which detects the process air temperature. The detection sensor 120 thus represents an actual variable to be controlled.The system is controlled by the blower unit 110 of the compressor 135, also known as the cooling air blower or fan.

[0027] A heat pump drying process is generally a continuous process in which the evaporation and condensation of the process air and the coolant and / or refrigerant are in balance. To keep this process in balance, the compressor 135 is cooled by means of an intelligent flow machine control system, the blower unit 110, and heat is thus extracted from the coolant and / or refrigerant. The control is based on the coolant and / or refrigerant temperature and the drum outlet temperature. It must be ensured that the coolant and / or refrigerant enters the compressor 135 superheated and that the process air in the condenser 155 is at a temperature that does not raise the laundry temperature above the predetermined temperature, for example, 40°C, upon evaporation.

[0028] Figure 2 shows a schematic representation of a drying device 100 according to an embodiment. The drying device 100 shown here can be Figure 1 described drying device 100. According to this embodiment, the drying device 100 also has a control system according to the control circuit diagram 116, which, however, differs from the one shown in Figure 1described control circuit diagram 116. According to this exemplary embodiment, the control circuit diagram 116 comprises an outer control loop 200 and an inner control loop 205 for controlling the blower unit 110. The process air temperature detected by the sensor device 105 is used as the reference variable 117 of the outer control loop 200, and the cooling and / or refrigerant temperature is used as the further reference variable 217 of the inner control loop 205. According to this exemplary embodiment, the blower unit 110 is controlled using the controlled variable 118, which includes the one controlled variable 218 of the inner control loop 205.

[0029] In other words, in Figure 2A cascaded control is shown, which enables a drying program in which a maximum temperature is not exceeded. The maximum temperature can be set, for example, by a user of the drying device 100. This allows the user to safely dry laundry that he washes at 40°C, for example, in the drying device 100, which is also referred to as a dryer for short.

[0030] For example, the process can be operated at a Pareto optimal operating point, which, for example, at a 40°C laundry temperature, provides an advantageous option with regard to process time, energy consumption and wear of the actuators in a heat pump drying process.

[0031] Figure 3 shows a schematic representation of a drying device 100 according to an embodiment. The drying device 100 shown here can be similar to the one shown in one of the Figures 1 or 2described drying device 100. According to this embodiment, the drying device 100 also has a control system according to the control circuit diagram 116, which, however, differs from the one shown in Figure 2 described control diagram 116. Although the control diagram 116 shown here also includes the outer control loop 200 and the inner control loop 205 as in Figure 2 However, the reference variable 117 of the outer control loop 200 according to this embodiment represents the cooling and / or refrigerant temperature. The further reference variable 217 of the inner control loop 205 represents the process air temperature. This means that the reference variables 117, 217 of the control loops 200, 205 according to this embodiment are compared to those from Figure 2are exchanged. Also according to this embodiment, the blower unit 110 is controlled using the controlled variable 118, which includes the one controlled variable 218 of the inner control loop 205.

[0032] Figure 4 shows a flowchart of a method 400 according to an embodiment for setting a drying temperature for a drying device. The method 400 can be carried out, for example, in a drying device as described in one of the Figures 1 to 3The method 400 comprises a reading step 405 and a control step 410. In reading step 405, a temperature signal representing a current process air temperature is read in via an interface to a sensor device of the drying appliance. In control step 410, a fan unit is controlled using a control signal. In control step 410, the cooling and / or refrigerant temperature is controlled using the temperature signal such that the laundry temperature does not exceed a predetermined setpoint. In this way, the process air temperature is set.

[0033] Optionally, in step 410 of the control process, the predetermined setpoint represents a program temperature selected in the washing program and / or a measured temperature. The measured temperature is detected, for example, by the sensor device of the drying device. Further optionally, in step 410 of the control process, the cooling and / or refrigerant temperature is controlled using a control algorithm with an outer control loop and / or an inner control loop in order to control the blower unit. More precisely, the process air temperature represents a reference variable of the outer control loop, and the cooling and / or refrigerant temperature represents a further reference variable of the inner control loop. Alternatively, for example, the cooling and / or refrigerant temperature represents the reference variable of the outer control loop, and the process air temperature represents the further reference variable of the inner control loop.Accordingly, the control signal according to this embodiment represents a control variable for controlling the blower unit, as is shown, for example, in the . Figures 2 and / or 3 was illustrated.

[0034] Figure 5 shows a block diagram of a control unit 115 according to an embodiment of a drying device. The control unit 115 can be Figure 1 described control unit 115 and is usable in a drying device as described in one of the Figures 1 to 3 The control unit 115 is further configured to control or carry out a method for setting a drying temperature for a drying device, as described in Figure 4has been described. According to this exemplary embodiment, the control unit 115 has a reading unit 500 and a providing unit 505. The reading unit 500 is designed to read a temperature signal 510. The temperature signal 510 represents a current process air temperature.

[0035] The laundry temperature signal 515 represents a current laundry temperature. For this purpose, the reading unit 500 reads the temperature signal 510 via an interface to a sensor device 105 of the drying appliance. Only optionally, the reading unit 500 is further configured to read a predetermined setpoint 520.

[0036] According to this embodiment, the provision unit 505 is designed to provide a control signal 525 for controlling a fan unit of the drying device.

Claims

1. Method (400) for carrying out a heat pump drying process for a drying appliance (100) having a heat pump (135, 145, 150, 155) and a fan (160) for generating process air, the method (400) comprising the following steps: - providing a process air flow; - reading in (405) a temperature signal (510), the temperature signal (510) representing a current process air temperature, via an interface to a sensor device (105) of the drying appliance (100); and - controlling (410) a fan unit (110) for extracting heat from the coolant or refrigerant using a control signal (525), characterised in that in the control step (410), a coolant and / or refrigerant temperature is controlled using the temperature signal (510) so that the laundry temperature does not exceed a predetermined target value (520) in order to adjust the process air temperature.

2. Method (400) according to claim 1, wherein in the control step (410), the fan unit (110), wherein the compressor (135) is cooled by means of the fan unit (110) and thus heat is extracted from the coolant and / or refrigerant.

3. Method (400) according to claim 1 or 2, wherein in the control step (410), the fan unit (110) is controlled using the control signal (525), wherein the predetermined target value (520) represents a program temperature selected in a washing program and / or a measured temperature.

4. Method (400) according to any of the preceding claims, wherein in the control step (410), the process air temperature and / or the coolant and / or refrigerant temperature is controlled using a control algorithm having an external control loop (200) and / or an internal control loop (205) in order to actuate the fan unit (110), wherein in the control step (410), the process air temperature represents a reference variable (117) of the external control loop (200) and the coolant and / or refrigerant temperature represents a further reference variable (217) of the internal control loop (205), or wherein the coolant and / or refrigerant temperature represents the reference variable (117) of the external control loop (200) and the process air temperature represents the further reference variable (217) of the internal control loop (205), and wherein the control signal (525) represents a control variable (118, 218) for controlling the fan unit (110).

5. Method (400) according to any of the preceding claims, wherein in the read step (405), the laundry temperature signal (515) represents the laundry temperature as the drum exit temperature plus a predetermined value.

6. Drying appliance (100) which is designed as a heat pump dryer or washer-dryer having a heat pump (135, 145, 150, 155) and comprises the following features: - a sensor device (105) for detecting a current process air temperature, a current coolant and / or refrigerant temperature and / or a current laundry temperature; - a fan unit (110) for controlling the process air temperature and / or the coolant and / or refrigerant temperature; and - a control unit (115) which is designed to carry out the steps (405, 410) of the method (400) according to any of the preceding claims in corresponding units (500, 505).

Images