EP2764816A1 - Household device with an air heating installation - Google Patents

Abstract

The household appliance has a control unit (14) for controlling a work process for cleaning or drying of treatment materials and a working chamber for receiving the treatment materials during the work process. An air heating unit (6) is provided for heating the working chamber by an air flow (LS). The air heater comprises a fan (7) for generating the air flow and a heater (8) for heating the air flow. The control unit is formed for influencing a volume flow of the air flow by influencing a rotational speed of the fan depending on a preset value (VW) for the volume flow of the air flow and depending on an actual value of the volume flow of the air flow. An independent claim is included for a method for operating a household appliance, particularly household dishwasher, household washer-drier or household drier.

Description

The present invention relates to a domestic appliance, in particular a domestic dishwasher, a household washer dryer or a household dryer, with a control device for controlling a process for cleaning and / or drying of treated, with a working chamber for receiving the material to be treated during the operation, and with an air heater for heating the working chamber by means of an air flow, which comprises a fan for generating the air flow and a heater for heating the air flow.

From practice a household dishwasher is known in which overheating of the air heater is prevented by means of a temperature controller. The temperature controller is a so-called two-point controller that alternately switches the power supply on or off. The regulation of the air heater takes place via a variable timing of the power supply. The temperature controller can also be supplemented by a temperature sensor.

In addition, the air heater is equipped with a fuse, which permanently interrupts the voltage supply of the air heater when a critical temperature is reached by melting. To restart the household dishwasher then replacement of the fuse is required.

Object of the present invention is to improve a household appliance with air heater.

The object is achieved in a household appliance of the type mentioned above in that the control device is designed to influence a volume flow of the air flow by influencing a speed of the fan based on a default value for the volume flow of the air flow and on the basis of an actual value of the volume flow of the air flow.

The domestic appliance according to the invention may in particular be a domestic dishwasher, which is provided that treated, namely ware, in particular to be washed dishes in a working chamber, also called rinsing chamber, introduced and in a single operation, which is also called rinse, with the aid of rinsing cleaned and then dried. Likewise, the household appliance according to the invention may be a household washing dryer, which is provided that treated, namely laundry, especially laundry to be washed, in a working chamber, also called wash chamber, introduced and in a single operation, which is also called wash, with the aid of wash liquor cleaned and then called in a further operation, also called drying cycle, in the wash chamber. Moreover, the household appliance according to the invention may be a household dryer, which is provided with material to be treated, namely drying material, in particular laundry to be dried, introduced into a working chamber, here also called a drying chamber, and called in one operation, also called a drying cycle the drying chamber is dried.

The household appliance according to the invention has a control device for the automatic control of operations of the household appliance. For this purpose, the control device can be designed as so-called sequence control, in particular as electronic sequence control. In addition or independently, it can also perform one or more control functions as needed for control purposes. In particular, it can be designed as a control unit which monitors and influences, preferably controls, the air volume flow.

In the following the invention will be explained by way of example on a domestic dishwasher. In the control device of the domestic dishwasher is at least one work program for performing a procedure for cleaning and / or drying items to be washed, in particular for washing dishes, deposited. Advantageously, several work programs are provided, one of which can be selected and started by the operator. This makes it possible to adapt the sequence of an operation in particular to the load, to the type of loading, to the degree of soiling of the items to be washed and / or to the desired duration of the operation.

An exemplary sequence of such an operation provides for cleaning the items to be washed several sub-operations, preferably in this order a pre-rinse for pre-cleaning items, a cleaning cycle for thorough cleaning of items, an intermediate rinse for removing soiled rinse liquor from the dishes and a rinse cycle to prevent stains on Items to be washed and / or to prepare a drying cycle, in which the items to be washed are each treated with rinsing liquor. These sub-operations are therefore referred to as partial water-bearing operations. Furthermore, the exemplary sequence provides a subsequent to the water-bearing sub-operations, Spülprozabschließenden sub-operation for drying the cleaned items, namely a drying cycle, before.

The pre-rinse cycle is used in the example, especially the removal of coarse dirt from the dishes. The purpose of the subsequent cleaning cycle is to completely remove contaminants from the items to be washed, for which purpose a rinsing liquid added with cleaning agent can be used. The now performed intermediate rinse serves in particular for the removal of detergent residues, which adhere to the items to be washed. The subsequent rinse cycle is in particular to avoid stains on the items to be washed, which could be caused by dissolved substances in the water, such as salt and / or lime. For this purpose, the rinsing liquid can be mixed with rinse aid during the rinse cycle.

Usually, a predetermined amount of liquid is introduced into the working chamber at the beginning of a water-carrying partial operation, so as to form a rinsing liquor for the respective partial operation. The rinse liquor of the partial work cycle is typically removed from the working chamber at the end of the partial work cycle. In this case, the temperature of the working chamber and the rinsing water therein is in many cases lower than is appropriate for the respective partial operation. Therefore, a modern household dishwasher usually has at least one heating device for heating the working chamber and the rinsing liquor. Conventionally, such a heater is designed as a water heater, wherein the heat by direct thermal contact of a preferably electric heater, in particular by heat conduction, on the Rinse liquor is transferred and is introduced by the rinsing liquor in the working chamber. In contrast, the household dishwasher according to the invention alternatively or additionally, a heating device designed as an air heater, in which the heat is transmitted by means of an air flow from a preferably electric heater, in particular by convection, in the working chamber and the rinsing liquor.

The air heater for heating the working chamber by means of an air flow of the household appliance according to the invention has a fan for generating the air flow and a heater for heating the air flow.

In this case, the control device is designed to influence a volume flow of the air flow by influencing a rotational speed of the fan on the basis of a default value for the volume flow of the air flow and on the basis of an actual value of the volume flow of the air flow.

By "influencing" is meant a controlling and / or regulatory influence. Furthermore, the "volume flow of the air flow" means a volume of air which is conveyed in a certain time.

According to the invention, this volume flow is influenced by the control device, in that the speed of the fan is influenced by the control device. In this case, the influencing of the speed of the fan and thus the volume flow on the basis of a default value, also called setpoint, for the flow rate and an actual value, also called the actual value, the volume flow takes place. In particular, can be provided for influencing the speed of the blower, a closed loop in which the actual value of the volume flow, the control variable, the default value for the flow rate, the command variable and the speed of the fan is the manipulated variable.

In this way, the volume flow can be regulated independently of disturbance variables to its default value, so that a sufficient heat dissipation from the heater is always guaranteed, whereby overheating of the heater is reliably prevented. In particular, such a reduction of the volume flow and a heater based thereon overheating due to an operator error, such. B. incorrectly placed material to be treated or too large amount of treated material to be prevented.

This can now be dispensed with the previously common temperature controller, which can simplify the design of the household appliance and cheaper. In addition, the maintenance frequency can be reduced because the frequency of melting the fuse can be reduced, which usually leads to a cost savings.

In addition, in the home appliance according to the invention, the life of the heater and adjacent to the heating components of the household appliance may be extended because due to the better heat dissipation, the thermal load of the heater or the adjacent components is reduced in case of failure.

According to an expedient development of the invention, the air flow is guided in a closed circuit from the working chamber via the heater back into the working chamber. For this purpose, one or more air ducts may be present from an outlet opening of the treatment chamber to the heater and from this back to an inlet opening of the treatment chamber. In this way results in an effective and efficient heating of the working chamber, since no heat is removed by means of the air flow to the outside.

According to an advantageous embodiment of the invention, the control device is designed to determine the default value as a function of at least one operating parameter of the household appliance. In this way, a situation-specific default value for the volume flow for influencing the volume flow can be used, so that the heat balance of the household appliance can be optimized. The default value can be read, inter alia, from a table stored in a memory or calculated by means of a function stored in a memory.

According to an expedient development of the invention, one of the operating parameters is a supply voltage supplied to the heater, which is preferably connected by means of a control device for transmitting measuring signals Voltage measuring device is measured. In this way, overheating of the heater due to an excessive supply voltage of the heater can be avoided. This is of particular concern because the supply voltage is generally the voltage of an external power supply, for example, the voltage of a conventional home network, which may easily be 10% to 20% above its nominal value. In addition, the supply voltage enters the power of the heater with its second power. The use of a voltage measuring device can ensure that the actual value of the supply voltage is always used to determine the default value for the volume flow.

According to an advantageous embodiment of the invention, one of the operating parameters is a rated power of the heater, wherein preferably the rated power is stored in the memory. The rated output is understood to be the highest heat output of the heater which can be output in continuous operation. By now the rated power is taken into account as an operating parameter, it is possible to use heaters with different power ratings in otherwise identical household appliances, without major changes must be made to the control device. Similarly, in a repair case, a faulty heater can be replaced by a heater with a different rated power. For this purpose, in particular the default value for the volume flow with increasing nominal power can be increased or lowered with decreasing nominal power. Thus, the respective heating can be operated at its optimum operating point. The rated power of the heater actually used can be stored in the control device, for example in an electronic memory or in the form of Codiersteckern or Codierschaltern.

According to an expedient development of the invention, one of the operating parameters is a switch-on duration of the heating, which is preferably measured by means of a time measuring device connected to the control device for transmitting measuring signals. The duty cycle is the time that has elapsed from switching on the heater until the observation time. In this way it can be prevented that forms a heat accumulation with increasing duty cycle, which thermally stressed the heating and / or their environment too much. For this purpose, in particular the default value for the volume flow with increasing duty cycle increase. The use of a time measuring device can ensure that always the actual value of the duty cycle is used to determine the default value for the flow rate.

According to an expedient development of the invention, the control device for detecting the actual value of the volume flow of the air flow is designed on the basis of the power consumption of the blower, which is preferably measured by means of a power measuring device connected to the control device for transmitting measuring signals. The power consumption of a blower is generally a measure of the respective delivered volume flow. The use of this knowledge makes it possible to dispense with a direct measurement of the volume flow, for example by means of an impeller. As a result, the structural design of the household appliance can be kept simple and at the same time a reliable detection of the volume flow can be ensured.

According to an advantageous development of the invention, the fan comprises an electric synchronous motor, preferably a permanent magnet synchronous motor, for example a BLDC motor or a BLAC motor, wherein preferably the speed of the synchronous motor via a control line by the control device can be predetermined .An electric synchronous motor is a synchronous machine in motor operation, in which a constantly magnetized rotor is taken in synchronously by a moving magnetic rotating field in the surrounding stator. In a permanent-magnet synchronous motor, the rotor comprises at least one permanent magnet. Furthermore, a BLDC motor is a brushless, permanent-magnet DC motor, and a BLAC motor is a brushless, permanent-magnet AC motor. The advantage of a synchronous motor in the present case lies in the rigid coupling of the rotational speed to the frequency of the mono- or polyphase alternating current usually generated by means of a controllable inverter, which generates the rotating field. By specifying the speed by the control device ensures that the desired speed is maintained at least in a normal operation, without the speed is controlled with a complex closed loop.

According to an expedient development of the invention, the control device is for monitoring a difference between the default value and the actual value formed, wherein for the difference, a tolerance limit is provided, when falling below a constant maintenance of the speed of the fan is provided, and / or the difference is provided a Abschaltgrenzwert, when exceeded for at least a predetermined period of time switching off the power of the heating by the Control device is provided. It can be effected by monitoring the difference and the provision of a tolerance limit that, with a tolerable small deviation of the actual value of the volume flow of the default value of the volume flow, an adjustment of the speed is omitted. In this way, a more pleasant sound image of the current dishwasher can be achieved. In particular, a periodically increasing and decreasing noise emission can be prevented. If the tolerance limit is exceeded, the speed can be adjusted to adjust the volume flow. By monitoring the difference and providing a switch-off threshold, it is ensured that the heating and / or adjacent areas of the heating and / or temperature-sensitive material to be treated in the working chamber do not overheat, even if the intended volume flow for a predetermined period of time can not be achieved because For example, the loading of the working chamber was carried out improperly and the air flow slows down too much. The minimum predefinable time period is determined by the reaction time of the control device and can be very close to zero.

According to an advantageous development of the invention, when the power of the heater is switched off, an error message is output via an operator interface. This allows the operator promptly take measures to eliminate any interference. For example, it may be prompted to remove laundry that obstructs the flow of air excessively. The operator interface can be assigned to the control device and can comprise indicator lamps, light-emitting diodes, an alpha-numeric display and / or a graphic display for outputting optical messages. Additionally or independently thereof, the operator interface for outputting audible messages may include a buzzer, a speaker and / or the like.

According to an advantageous embodiment of the invention, the air heater on a sorption with a reversibly dehydratable material, which when the heater is switched off to absorb moisture from the air flow and is formed when the heater is switched on for the delivery of moisture to the air flow. This makes it possible to generate the air flow by means of the blower in a drying cycle and with heating switched off the air heater so that the absorbed in the working chamber by the air flow from the treated moisture is released from the air flow to the sorption, which the air flow and thus the material to be treated dries. At the latest when the capacity of the sorption is exhausted, then a desorption of the sorption can be done by the heating of the air heater and the fan is turned on. This results in a heated air flow, on the one hand absorbs moisture from the sorption and on the other hand can be used to heat the working chamber. In this way, an excellent drying result can be achieved and at the same time the waste heat can be usefully used in desorbing the sorption device, so that the energy consumption of the household appliance is reduced.

Furthermore, the invention relates to a method for operating a household appliance, in particular a domestic dishwasher, a Haushaltswaschtrockners or a household dryer, in which by means of a control device, an operation for cleaning and / or drying of cleaning material is controlled, in which the cleaning received in a working chamber during the operation is and in which the working chamber is heated by means of an air flow of an air heater, wherein the air flow is generated (by means of a blower and heated by means of a heater.

It is provided that a volume flow of the air flow is influenced by the control device by a speed of the blower is influenced by a default value for the volume flow of the air flow and based on an actual value of the volume flow of the air flow.

The inventive method allows safe operation of a household appliance with an air heater.

Advantageous embodiments and further developments of the method according to the invention are explained in the description of the claimed household appliance.

The above-explained and / or reproduced in the subclaims advantageous embodiments and refinements of the invention can - in addition to z. B. in cases of clear dependencies or incompatible alternatives - individually or in any combination with each other.

Figur 1

ein vorteilhaftes Ausführungsbeispiel einer erfindungsgemäßen Haushaltsgeschirrspülmaschine in einer schematischen Seitenansicht

Figur 2

eine Darstellung eines Regelkreises der Geschirrspülmaschine der Figur 1 und

Figur 3

ein Diagramm zur Darstellung der Funktionsweise der Haushaltsgeschirrspülmaschine der Figuren 1 und 2.

The invention and its advantageous embodiments and further developments and advantages thereof are explained in more detail below with reference to a drawing. In a schematic schematic diagram:

FIG. 1

an advantageous embodiment of a household dishwasher according to the invention in a schematic side view

FIG. 2

a representation of a control loop of the dishwasher of FIG. 1 and

FIG. 3

a diagram illustrating the operation of the household dishwasher of the FIGS. 1 and 2 ,

In the following figures, only those components of a domestic dishwasher are provided with reference numerals and explained, which are required for the understanding of the invention. It goes without saying that the household dishwasher according to the invention can comprise further parts and assemblies.

FIG. 1 shows an embodiment of a household dishwasher according to the invention 1 in a schematic side view. The domestic dishwasher 1 has a rinsing chamber 2, in which items to be washed, not shown, can be cleaned by means of a rinsing liquid S during a rinse cycle. The rinsing liquid S introduced into the rinsing chamber 2 collects in a sump 3, which is arranged on a lower section of the rinsing chamber 2, due to its gravitational force. An example arranged on or in the sump pump 3 circulation pump 4 makes it possible to spray the rinsing liquid S via a spray system 5 in the rinsing chamber 2, so as to clean the items to be washed and / or treated in any other way. The circulation pump 4 may in particular be a heating pump 4, which has a water heater for additional heating of the rinsing water.

In order to heat the rinsing liquid S to an appropriate temperature, an air heater 6 is provided for heating the working chamber 2 by means of an air flow LS, which comprises a fan 7 for generating the air flow LS and a heater 8, 9 for heating the air flow LS in the embodiment , The heater 8 comprises a heating element 9 for the delivery of heat to the air flow LS. If now the fan 7 and the heater 8 are turned on, it is sucked through a suction port 10 of the washing chamber 2 air from the washing chamber 2 and as air flow LS through a first air line 11 to the fan 7, from there to the heating element 9 of the heater 8, through which he is heated, and from there through a second air line 12 via an exhaust port 13 back into the washing chamber 2. In the rinsing chamber 2, the air stream releases heat, so that the rinsing chamber 2 and the rinsing bath S are heated. In the embodiment, therefore, the air flow LS is guided in a closed circuit from the washing chamber 2 via the heater 8 back into the washing chamber 2. In this way results in an effective and efficient heating of the washing chamber 2 and the rinsing liquor LS, since by means of the air flow LS no heat is removed to the outside.

The dishwasher 1 also has a control device 14 for the automatic control of operating sequences of the domestic dishwasher 1. For this purpose, the control device 14 can be designed as a so-called sequence control, in particular as an electronic sequence control 14. In addition or independently, it can also perform control functions. At least one wash program for controlling a wash cycle for washing items to be washed, in particular for washing dishes, is stored in the control device 14. Advantageously, several wash programs are provided, one of which can be selected and started by the operator. This makes it possible to adjust the sequence of a rinse cycle in particular to the load, to the type of loading, to the degree of soiling of the items to be washed and / or to the desired duration of the rinse cycle.

In order to supply the electrical consumers of the domestic dishwasher 1 with electrical energy, the domestic dishwasher 1 of the embodiment has an electrical connection line 15, which is for connecting the domestic dishwasher 1 to an external power supply SV is provided. The connecting line 15 is connected to a plurality of supply lines 16, 17, which are in turn connected to at least one electrical load of the household dishwasher. A first supply line 16 supplies the blower 7 with electrical energy during operation of the domestic dishwasher 1. Furthermore, a second supply line 17 supplies the heater 8 with electrical energy during operation of the domestic dishwasher 1. It goes without saying that even more, not shown supply lines can be present.

The rotational speed of the fan 7 in the exemplary embodiment can be influenced by the control device 14, preferably via a first control line 18. For this purpose, a control signal ST can be provided, which can be transmitted from the control device 14 to the blower 7 via the control line 18.

In the exemplary embodiment, the control device 14 is assigned a preferably electronic memory 19, which is preferably connected to the control device 14 via a first data line 20 for data exchange. In particular, preset value values VW for the volume flow of the air flow LS in the form of tables or functions and a nominal power PN of the heater 8 can be stored in the memory, which are then transferable to the control device 14.

Furthermore, the exemplary domestic dishwasher 1 comprises a power measuring device 21 for measuring the power consumption, in particular electrical power consumption, of the blower 7, which may be designed, for example, as a current measuring device 21, which is provided for measuring the current in the first supply line 16. The power consumption of the blower 7 is a measure of the actual volume flow TW of the air flow LS. In this case, the measured actual volume flow TW can preferably be transmitted by the power measuring device 21 to the control device 14 via a first measuring line 22.

In addition, the domestic dishwasher 1 of the exemplary embodiment has a voltage measuring device 23 for measuring the supply voltage UV of the heater 8. The measured supply voltage UV is for example via a second measuring line 24 to the control device 14 transferable.

Likewise, the dishwashing machine 1 of the exemplary embodiment has a time measuring device 25 for measuring the switch-on duration TE of the heater 8. The measured switch-on duration TE can be transmitted to the control device 14 via a third measuring line 26, for example.

Furthermore, the exemplary domestic dishwasher 1 comprises a second control line 27, which is provided for influencing the heater 8 by the control device 14.

In the exemplary embodiment, the air heater 6, a sorption 28 with a reversibly dehydratable material 29, which is formed with the heater 8 to absorb moisture from the air flow LS and switched on heater 8 for emitting moisture to the air flow LS. This makes it possible to generate the air flow LS by means of the blower 7 in a drying cycle and with switched off heater 8 of the air heater 6 so that the recorded in the rinsing chamber 2 by the air flow LS from the ware moisture from the air flow LS to the sorption 22nd is discharged, which dries the air flow LS and thus the items to be washed. At the latest when the absorption capacity of the sorption device 22 is exhausted, desorption of the sorption device 22 can take place by switching on the heater 8 of the air heating device 6 and the fan 7. This results in a heated air flow LS, on the one hand receives moisture from the sorption 21 and on the other hand for heating the rinsing chamber 2 and the rinsing S, for example, the rinsing S of a cleaning cycle, can be used. In this way, an excellent drying result can be achieved, and at the same time the waste heat can be usefully used in desorbing the sorption device 21, so that the energy consumption of the household dishwasher 1 is reduced.

Furthermore, the domestic dishwasher 1 of the embodiment has an operating interface 30, which for displaying optical messages display lamps, LEDs, an alpha-numeric display and / or a graphical Display and / or for the output of acoustic messages may have a buzzer, a speaker and / or the like. The user interface 30 is connected to the control device 14 via a third data line 31, so that it can be influenced by the control device 14.

According to the invention, the control device 14 is designed to influence a volumetric flow of the airflow LS by influencing a rotational speed of the fan 7 on the basis of a preset value VW for the volumetric flow of the airflow LS and on the basis of an actual value TW of the volumetric flow of the airflow LS.

In this case, this volume flow is influenced by the control device 14 in that the speed of the fan 7 is influenced by the control device 14 via the first control line 18. In this case, the influencing of the rotational speed of the fan 7 and thus of the volume flow on the basis of a default value VW, also called desired value VW, for the volume flow and an actual value TW, also called actual value TW, the volume flow. In this way, a closed loop can result, wherein the actual value TW of the volume flow is the controlled variable, the default value VW for the volume flow, the reference variable and the speed of the fan 7 is the manipulated variable.

In this way, the volume flow can be regulated independent of disturbance variables to its default value VW, so that a sufficient heat dissipation from the heater 8 is always ensured, whereby overheating of the heater 8 is reliably prevented. In particular, such a reduction of the volume flow and based on overheating of the heater 8 due to an operator error, such. B. incorrectly placed material to be treated or too large amount of treated material to be prevented.

This can now be dispensed with the previously common temperature controller, which can simplify the design of the household appliance 1 and cheaper. In addition, the maintenance frequency can be reduced because the frequency of melting the fuse can be reduced, which usually leads to a cost savings.

In addition, in the household appliance 1 according to the invention, the life of the heater 8 and adjacent to the heater 8 components of the household appliance 1 may be extended because due to the better heat dissipation, the thermal load of the heater 8 and the adjacent components is reduced in case of failure.

Preferably, the air flow LS is guided in a closed circuit from the working chamber 2 via the heater 8 back into the working chamber 2. In this way results in an effective and efficient heating of the working chamber 2, since by means of the air flow LS no heat is removed to the outside.

Conveniently, the control device 14 is designed to determine the default value VW as a function of at least one operating parameter UV, PN, TE of the household appliance 1. In this way, a situation-specific default value VW for the volume flow for influencing the volume flow can be used, so that the heat balance of the household appliance 1 can be optimized. The default value VW can be read from among other things from a table stored in a memory 19 or calculated by means of a stored in a memory 19 function.

Advantageously, one of the operating parameters UV, PN, TE is a supply voltage UV supplied to the heater 8, which is preferably measured by means of a voltage measuring device 23 connected to the control device 14 for transmitting measuring signals. In this way, overheating of the heater 8 due to a too high supply voltage UV of the heater 8 can be avoided. This is of particular concern because the supply voltage UV is generally the voltage of an external power supply SV, for example the voltage of a conventional home network, which may easily be 10% to 20% above its nominal value. In addition, the supply voltage UV enters the power of the heater 8 with its second power. The use of a voltage measuring device 23 can ensure that the actual value of the supply voltage UV is always used for determining the preset value VW for the volume flow. Advantageously, one of the operating parameters UV, PN, TE is a rated power PN of the heater 8, wherein preferably the nominal power PN is stored in the memory 23. Under the nominal power PN is understood to be the highest output in continuous operation heat output of the heater 8. By now the rated power PN is considered as operating parameters UV, PN, TE, it is possible to use 1 heaters 8 with different nominal power PN for otherwise identical household appliances without major changes must be made to the controller 14. Likewise, in a repair case, a defective heater 8 can be exchanged for a heater 8 with a different nominal power PN. For this purpose, in particular the default value VW for the volume flow with increasing nominal power PN can be increased or lowered with decreasing nominal power PN. Thus, the respective heater 8 can be operated at its optimum operating point. The nominal power PN of the actually used heater 8 can be deposited in or on the control device 14, for example in an electronic memory 23 or in the form of coding plugs or coding switches.

Preferably, one of the operating parameters UV, PN, TE is a switch-on time or switch-on time duration and thus heating duration TE of the heater 8, which is preferably measured by means of a time measuring device 25 connected to the control device 14 for transmitting measuring signals. The duty cycle or heating time TE is the time that has elapsed from switching on the heater 8 to the observation time. In this way it can be prevented that with increasing duty cycle TE forms a heat accumulation, which thermally stresses the heater 8 and / or their surroundings too much. For this purpose, in particular the default value VW for the volume flow with increasing duty cycle TE can be increased. The use of a time measuring device 25 can ensure that always the actual value of the duty cycle TE is used to establish the default value VW for the volume flow.

In the exemplary embodiment, the control device 14 is designed to detect the actual value TW of the volume flow of the air flow LS on the basis of the power consumption of the blower 7, which is preferably measured by means of a power measuring device 21 connected to the control device 14 for transmitting measurement signals. The power consumption of a blower 7 is generally a Measure for the respective delivered volume flow. The use of this knowledge makes it possible to dispense with a direct measurement of the volume flow, for example by means of an impeller. As a result, the structural design of the household appliance 1 can be kept simple and at the same time a reliable detection of the volume flow can be ensured.

Preferably, the blower 7 comprises an electric synchronous motor, preferably a permanent-magnet synchronous motor, for example a BLDC motor or a BLAC motor, wherein preferably the speed of the synchronous motor via a control line 18 by the control device 14 can be predetermined. An electric synchronous motor is a synchronous machine in engine operation in which a magnetizer which is constantly magnetized is driven synchronously by a moving magnetic rotating field in the surrounding stator. In a permanent-magnet synchronous motor, the rotor comprises at least one permanent magnet. Furthermore, a BLDC motor is a brushless, permanent-magnet DC motor, and a BLAC motor is a brushless, permanent-magnet AC motor. The advantage of a synchronous motor in the present case lies in the rigid coupling of the rotational speed to the frequency of the mono- or polyphase alternating current usually generated by means of a controllable inverter, which generates the rotating field. By specifying the speed by the control device 14 ensures that the desired speed is maintained at least in a normal operation, without the speed is controlled with a complex closed loop.

FIG. 2 shows a representation of a control loop of the dishwasher of FIG. 1 , In this case, the control device 14 is designed as a controller such that it from the memory 19 supplied as a reference variable default value VW for the flow rate VS and from the fed it from the power meter 21 as a controlled variable actual value TW of the flow rate VS a control signal ST to place the speed DZ of the blower 7, which represents the manipulated variable of the control loop generates. The flow rate VS results from the rotational speed DZ of the blower 7 and from the marginal conditions acting as disturbance variables SG, such as an adjustment of the suction opening 10 and / or the blow-out opening 13 with items to be washed or other items by the operator. Now occurs such a disturbance SG or changes such a disturbance SG, then the volume flow VS of the air flow LS changes. This is detected by the power measuring device 21, so that the actual value TW of the volume flow VS transmitted to the control device likewise changes. Now, at least when the volume flow VS changes to an intolerable degree, the control device 14 can adjust the control signal SG, so that the volume flow VS again assumes a tolerable actual value TW.

FIG. 3 shows a diagram illustrating the operation of the household dishwasher of FIGS. 1 and 2 , Shown are an example of the time course of the default value VW, the actual value TW and the difference DI from the default value VW and the actual value TW after the blower is switched on at the time t = 0. In this case, the control device 14 is designed to monitor a difference DI from the default value VW and the actual value TW, wherein a tolerance limit value TGW is provided for the difference DI, below which a constant maintenance of the speed DZ of the blower 7 is provided, and / or for the difference DI is a switch-off limit value AGW is provided, when exceeding this for at least a predetermined minimum period of time, a shutdown of the power of the heater 8 is provided by the control device 14.

In this case, by monitoring the difference DI and providing a tolerance limit value TGW, it can be effected that, given a tolerably small deviation of the actual value TW of the volume flow VS from the default value VW of the volume flow VS, an adjustment of the rotational speed DZ is omitted. In this way, a more pleasant sound image of the current dishwasher 1 can be achieved. In particular, a periodically increasing and decreasing noise emission can be prevented. If the tolerance limit value TGW is exceeded, then the rotational speed DZ can be adapted to adjust the actual value TW of the volumetric flow rate VS.

By monitoring the difference DI and the provision of a switch-off threshold AGW is ensured that the heater 8 and / or adjacent areas of the heater 8 and / or temperature-sensitive material to be treated in the working chamber 2 does not overheat even if the intended flow rate VS for a predetermined period of time can not be achieved because, for example, the loading of the working chamber 2 was carried out improperly and the air flow LS brakes too much. The minimum predefinable time period is determined by the reaction time of the control device 14 and can be very close to zero.

In the example of FIG. 3 is the speed DZ and thus the actual value TW of the volume flow VS starting from zero increased until the difference DI falls below the tolerance limit TGW. Then the speed and thus the flow rate VS is kept constant. The preset value VW, the tolerance limit value TWG and the switch-off limit value are constant over time. However, it could also be provided that these values are variable over time. In particular, the default value VW could be increased over time in order to prevent that forms with increasing duty cycle ET of the heater 8, a heat accumulation, which thermally stressed the heater 8 and / or their surroundings too much. Would, which is not shown, for example, by improper loading of the dishwasher 1, the difference DI run for a predetermined period above the Abschaltgrenzwertes AGW, then the power of the heater 8 would be turned off.

When switching off the power of the heater 8, an output of an error message preferably takes place via an operator interface 30. In this way, the operator can promptly take measures to eliminate a possible fault. For example, it may be prompted to remove material to be treated, which hinders the airflow LS excessively. The operator interface 30 may be associated with the controller 14 and include display lamps, LEDs, an alpha-numeric display, and / or a graphical display for outputting optical messages. Additionally or independently thereof, the operator interface 30 for outputting audible messages may include a buzzer, a speaker, and / or the like.

The core of the invention is to equip the fan 7 of the drying system with a volume flow control. The specification for this regulation is a nominal volume flow, which depends on the heating time or on-time TE, heating capacity PN and mains voltage can be UV. Thus, the system is operated at the optimum operating point.

The actual volumetric flow can be detected via the PMSM (Permanent Magnet Excited Synchronous Motor).

The manipulated variable in the control loop can be the motor speed of the PMSM.

The different required volume flow rates as a function of the mains voltage can be stored in a look-up table or a function.

It can be provided in the volume flow parameterization of the fan 7, a control range (change in speed) and a cut-off for the heater to protect them and to avoid a customer service.

If the setpoint value for the air volume flow is not reached within a certain time frame, then the heater 8 can not be switched on at all or, if it is already switched on, be switched off.

Thus, possible operator errors (for example, if the operator partially adjusts the intake passage 10 and thereby reduces the volume flow at the same fan speed) can be prevented and counteracted.

• Kein Temperaturregler erforderlich.
• Kein Temperatursensor erforderlich.
• Erkennung von Fehlhandlungen des Bedieners (Luftkreislauf unterbrochen/eingedrosselt).
• Deutliche Senkung der Kundendiensteinsätze aufgrund Erkennung der Fehlhandlungen.
• Konstantes Behandlungsergebnis (z. B. Trocknungsergebnis bei einer Geschirrspülmaschine) unabhängig von der Netzspannung oder vom Bedienverhalten (z. B. Geschirreinräumung) des Bedieners.

In particular, the following advantages may result:

• No temperature controller required.
• No temperature sensor required.
• Detection of operator errors (air circulation interrupted / throttled).
• Significant reduction in customer service calls due to detection of malfunctions.
• Constant treatment result (eg drying result with a dishwashing machine) independent of the mains voltage or the operating behavior (eg dishwashing) of the operator.

LIST OF REFERENCE NUMBERS

1

Home appliance, household dishwasher

2

Working chamber, rinsing chamber

3

sump

4

circulating pump

5

spray system

6

air heater

7

fan

8th

heater

9

heating element

10

suction

11

first air line

12

second air line

13

exhaust vent

14

control device

15

connecting cable

16

first supply line

17

second supply line

18

first control line

19

Storage

20

first data line

21

Power measurement device

22

first measuring line

23

Voltage measuring device

24

second measuring line

25

Time measuring device

26

third measuring line

27

second control line

28

sorption

29

reversibly dehydratable material

30

Operator interface

31

third data line

SV

external power supply

LS

airflow

VW

default

TW

actual value

UV

supply voltage

PN

rated capacity

TE

duty

ST

control signal

VS

flow

SG

disturbance

DI

difference

TGW

tolerance limit

AGW

trip limit

Claims (12)

Household appliance, in particular household dishwasher (1), household washer dryer or household dryer, with a control device (14) for controlling a process for cleaning and / or drying of treated material, with a working chamber (2) for receiving the material to be treated during the operation, and with an air heater ( 6) for heating the working chamber (2) by means of an air flow (LS), which comprises a fan (7) for generating the air flow (LS) and a heater (8) for heating the air flow (LS), characterized in that the control device (14) for influencing a volume flow (VS) of the air flow (LS) by influencing a rotational speed (DZ) of the blower (7) on the basis of a default value (VW) for the volume flow of the air flow (LS) and on the basis of an actual value (TW) of the Volume flow (VS) of the air flow (LS) is formed. Domestic appliance according to the preceding claim, characterized in that the air flow (LS) in a closed circuit from the working chamber (2) via the heater (8) back into the working chamber (2) is guided. Domestic appliance according to one of the preceding claims, characterized in that the control device (14) for determining the default value (VW) in dependence on at least one operating parameter (UV, PN, TE) of the household appliance ( 1 ) is formed, wherein preferably the default value (VW ) is readable from a table stored in a memory (19) connected to the control device (14) for data exchange or can be calculated by means of a function stored in a memory (19) connected to the control device (14) for data exchange. Domestic appliance according to the preceding claim, characterized in that one of the operating parameters (UV, PN, TE) is a supply voltage (UV) supplied to the heater (8) which is preferably connected to the control device (14) for transmitting measuring signals by means of a voltage measuring device (23 ) is measured. Domestic appliance according to one of claims 3 or 4, characterized in that one of the operating parameters (UV, PN, TE) is a rated power (PN) of the heater (8), wherein preferably the nominal power (PN) is stored in the memory (19) , Domestic appliance according to one of claims 3 to 5, characterized in that one of the operating parameters (UV, PN, TE) is a duty cycle (TE) of the heater (8), which preferably by means connected to the control device (14) for transmitting measurement signals Time measuring device (25) is measured. Domestic appliance according to one of the preceding claims, characterized in that the control device (14) for detecting the actual value (TW) of the volume flow of the air flow (LS) is formed on the basis of the power consumption of the blower (7), which is preferably connected to the control device (FIG. 14) for transmitting measurement signals connected to the power measuring device (21) is measured. Domestic appliance according to one of the preceding claims, characterized in that the fan (7) comprises a synchronous electric motor, preferably a permanent-magnet synchronous motor, for example a BLDC motor or a BLAC motor, wherein preferably the speed (DZ) of the synchronous motor via a control line (18) can be predetermined by the control device (14). Domestic appliance according to one of the preceding claims, characterized in that the control device (14) for monitoring a difference (DI) from the default value (VW) and the actual value (TW) is formed, wherein for the difference (DI) a tolerance limit (TGW ) is provided, at which falls below a constant maintenance of the rotational speed (DZ) of the blower (7) is provided, and / or for the difference (DI) a Abschaltgrenzwert (AGW) is provided, when exceeded for at least a predetermined period of time a shutdown of Power of the heater (8) by the control device (14) is provided. Domestic appliance according to the preceding claim, characterized in that when switching off the power of the heater (8) an output of an error message via an operator interface (30). Domestic appliance according to one of the preceding claims, characterized in that the air heating device (6) has a sorption device (28) with a reversibly dehydratable material (29), which when the heater (8) for receiving moisture from the air flow (LS) and at turned-on heater (8) for emitting moisture to the air flow (LS) is formed. Method for operating a domestic appliance (1), in particular a domestic dishwasher (1), a household washer dryer or a household dryer, in particular according to one of the preceding claims, in which a work operation for cleaning and / or drying of laundry is controlled by means of a control device (14), in which the material to be treated is received in a working chamber (2) during the operation and in which the working chamber (S) by means of an air flow (LS) of an air heater (6) is heated, wherein the air flow (LS) by means of a blower (7) and is heated by a heater (8), characterized in that a volume flow (VS) of the air flow (LS) is influenced by the control device (14) by a speed (DZ) of the blower (7) based on a default value (VW) for the volume flow (VS) of the air flow (LS) and on the basis of an actual value (TW) of the volume flow of the air flow (LS) we influence d.

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