EP2947197A1 - Dryer with internal cleaning of a water level sensor and method for the operation of same - Google Patents

Abstract

The invention relates to a dryer 1 with a drying chamber 2 for items to be dried 3, a process air duct 4, in which a blower 5 for the transport of process air, a heat sink 21, a heat source 23 and a lint filter 12 are located, a control unit 18 and a Water level sensor 8.9 in a condensate pan 6, which is associated with the heat sink 21 for collecting condensate, wherein the water level sensor 8.9 a vibration sensor 19 is mounted. The invention also relates to a method of operating this dryer.

Description

The invention relates to a dryer with a drying chamber for items to be dried, a process air duct in which a blower for the transport of process air, a heat sink, a heat source and a lint filter, a control unit, a water level sensor in a condensate pan, which the heat sink for Collecting condensate is associated, as well as a method of operation of this dryer.

The term "dryer" used herein is not only used for laundry dryers in the true sense, but also for washer-dryer, so for combination devices, with which a washing of laundry items can be performed.

The term "fluff" as used herein means all impurities which can pass from the drying chamber into the process air channel during the course of a drying process with moist laundry items and can be deposited in the process air channel, in heat exchangers and in a condensate tray. In addition to fluff in the actual sense, this includes other foreign particles such as e.g. Hair and dust.

The term "water level sensor" as used herein means a sensor capable of detecting the presence of, in particular, an aqueous liquid.

In a dryer, in particular in a condensation dryer, air (so-called process air) through a fan via a heater in a wet laundry containing drying chamber, usually a drum, passed. The hot air absorbs moisture from the laundry to be dried. After passing through the drying chamber, the then moist, warm process air is passed into a heat exchanger as a heat sink, where the moist, warm process air is cooled while the water condenses out. The lint filter is generally preceded by a lint filter for filtering lint from the moist, warm process air stream that originates from the laundry items. In addition, in the heat exchanger due to the therein In the prevailing humid atmosphere, it is particularly easy to separate fluff from the laundry items, in particular finely divided lint, if a lint filter is present which already catches larger lint. Such deposits in the heat exchanger can lead to a reduction in the efficiency of the heat exchanger. Moreover, when using a lint filter between the drum and the heat exchanger, it is possible for the lint filter to become clogged and then present a significant flow resistance. Frequently, therefore, these parts are rinsed with an aqueous liquid (eg condensate). Therefore, dryers with an internal cleaning device, in particular also those with a flushing device, have been developed. In tumble dryers equipped with an internal cleaning, lint is often collected in a cassette. As a result, the cassette (herein also referred to as "fluff depot") fills with lint over time and generally needs to be emptied.

That's how it describes WO 2010/028992 A2 a dryer comprising a drying chamber for receiving a moist material and a process air guide for supplying process air into the drying chamber and for discharging process air from the drying chamber, which process air guide a heat source for heating the process air before it enters the drying chamber and a heat sink for cooling the process air after its exit from the drying chamber, as well as arranged between the drying chamber and the heat sink first lint filter for collecting lint from the process air has. The first lint filter is associated with a first cleaning device, which comprises a collector for a liquid, a first flushing line connected to the collector, a first control element located in this first flushing line and a first distributor connected to the first flushing line for distributing liquid conveyed through the first flushing line to the first lint filter and to receive trapped lint from the first lint filter and a first drain for discharging the liquid with the collected lint from the first lint filter to the collector.

The WO 2012/022803 A1 describes a laundry treatment appliance, in particular a tumble dryer, which has a sieve receptacle for receiving a sieve, wherein the sieve receiving a level measuring device for measuring at least one water level is assigned to the Siebaufnahme and wherein the Siebaufnahme is connected to a flood chamber according to the principle of communicating vessels and at least a Level measuring device for measuring at least one level of the flood chamber is arranged and arranged. In a preferred embodiment, a plurality of sensors are at least partially disposed in the flood chamber, which respond to different levels of a liquid in the flood chamber. To detect the level in a river depot, it is thus out of the WO 2012/022803 A1 It is known to use a sensor arranged in the creek depot (also referred to herein as a "trap sensor") with which a backflow of aqueous liquid is detected in the creek depot. This sensor is generally located within the lint-contaminated liquid or wet lint mass. Although it can also be arranged in a sensor filled with relatively clean aqueous liquid flood chamber. However, such a structure is complex.

In any case, a more or less large part of the lint generally arrives in a condensate tray usually arranged below a heat exchanger, frequently in the so-called bottom group of a dryer. From the condensate pan or the bottom group, the condensate is normally pumped into a condensate tank, where it is temporarily stored either for later use or disposal. In doing so, the condensate generally collected in the underbody is pumped into an upper condensate tank at certain times, which are usually correlated with certain events. So that the bottom group does not overflow and in particular in time an aqueous liquid collected therein is pumped into the condensate tank, the water level in the floor group is frequently monitored by means of water level sensors. However, these water level sensors may be impaired in their operation by deposits of lint, detergent residues and general dirt. For proper operation of a dryer with water level sensors therefore an internal cleaning of the water level sensors would be useful.

The DE 10 2006 006 080 A1 describes a cleaning device for a disposed within a process air circuit of a household laundry dryer component, in particular for a heat exchanger, with a channel region of the process air circuit to flood the component via an inlet with a cleaning liquid to flood after completion of the cleaning process via a Discharge the obstruction is. The channel region is assigned an exciter device, with which the cleaning liquid to move. In particular, the exciter device comprises at least one wall section of the channel region which is to be vibrated by means of a drive. The drive comprises in particular an ultrasound generator.

Against this background, it was an object of the present invention to provide a dryer with a water level sensor in a condensate pan, wherein the water level sensor can be cleaned internally. Also to be provided is a method of operating this dryer.

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

The invention thus relates to a dryer with a drying chamber for laundry items to be dried, a process air duct in which a blower for the transport of process air, a heat sink, a heat source and a lint filter, a control unit and a water level sensor in a condensate pan, which Heat sink is assigned for collecting condensate, wherein the water level sensor is mounted a vibration sensor. The vibration transmitter is thus in mechanical contact with the water level sensor. The term "water level sensor" as used herein means not only a single sensor but also a system of multiple sensors, particularly two water level sensors.

In the case of the dryer, the heat source serves to heat the process air before it enters the drying chamber and the heat sink cools down the process air after it leaves the drying chamber.

The process air duct can be open or closed, so that the dryer according to the invention can be an exhaust air dryer or a circulating air dryer. According to the invention, the dryer is preferably a circulating air dryer.

The vibration generator generally has the task of causing the water level sensor in sufficiently large oscillations, so that, in particular, in cooperation with an aqueous liquid in the condensate pan, in which immersed the at least one water level sensor, prevents the deposit of fluff at the water level sensor or existing deposits of Lint can be removed. "Preventing" a deposit here means in particular that even at a relatively early point in time, when possibly only too loose deposits, but not yet too difficult to remove deposits have occurred on the water level sensor, a cleaning is performed. Then already satisfy a short cleaning phase and / or a cleaning phase with a low frequency and / or power of the vibration generator according to the inventive method for the cleaning of the water level sensor.

As long as these tasks are fulfilled, the vibration generator according to the invention is not limited. Preferably, the vibration generator comprises an electric motor, wherein the vibration sensor then more preferably has a linear electric motor with an imbalance. Such electric linear motors are used for example in electric toothbrushes.

The attachment of the vibration sensor to the water level sensor and thus the mechanical contact between the vibration sensor and the water level sensor can be realized in different ways, depending in particular on the type and construction of the vibration sensor and / or the water level sensor. Thus, an electric linear motor with an imbalance can be attached directly to a corresponding point of the at least one water level sensor. The "restless" run of the electric motor can then be transferred directly to the water level sensor. Alternatively, for example, a crank drive may be present, which is driven by an electric motor. Such a crank drive may for example comprise a flywheel, to which a crank rod is articulated eccentrically. The connecting rod can in turn be pivotally connected to the water level sensor.

In a most preferred embodiment of the dryer, the vibrator is a piezoelectric ultrasonic generator.

It is also preferred that the at least one water level sensor is a conductivity sensor and / or an optical sensor.

In the event that the at least one water level sensor is an optical sensor, this generally comprises a transmitter and a receiver for electromagnetic radiation, so that based on a weakening of an incoming at the receiver electromagnetic radiation signal on the presence of an aqueous liquid in front of the optical sensor closed can be. Moreover, by monitoring the intensity of the radiation signal, it is also possible to conclude on the degree of contamination or possibly inadequate cleaning of the water level sensor with the aid of the vibration transmitter.

In a most preferred embodiment of the invention, the at least one water level sensor is a conductivity sensor comprising a pair of electrodes between which an electrical voltage is applied. Since the conductivity of water is significantly greater than that of air, by measuring the conductivity, it can be concluded that there is water between the two electrodes. Moreover, by monitoring the electrical resistance or the electrical conductivity between the electrodes, it is also possible to conclude on the degree of contamination or a possibly insufficient cleaning of the water level sensor with the aid of the vibration transmitter.

The arrangement of the electrodes in the condensate tray, also referred to herein as a bottom tray, is not limited in accordance with the invention. However, it has been found that, in a preferred embodiment of the invention, the at least one water level sensor is attached to an upper wall, in particular a ceiling, of the condensate tray.

Moreover, a dryer is preferred in which the vibration sensor is mounted on a sensor base, wherein the sensor base is the part of the water level sensor, via which the water level sensor is connected to the condensate pan or a wall thereof.

Finally, it has proved to be advantageous according to the invention that the power consumption of the vibration generator is in the range of 20 W to 80 W, more preferably in the range of 30 W to 70 W and most preferably in the range of 40 W to 55 W.

Moreover, according to the invention, the oscillation frequency of the vibration generator preferably lies in the range from 50 kHz to 100 kHz, preferably in the range from 70 kHz to 90 kHz, for example at 80 kHz.

In a preferred embodiment, the dryer has an optical and / or acoustic display device, which indicates the execution of a cleaning of the at least one water level sensor by the operation of the vibration generator. In addition, the visual and / or audible indicator may allow the user of the dryer to view e.g. Allow operating parameters and / or an expected duration of the drying process.

It has proven to be advantageous that the at least one water level sensor and the vibration generator are arranged in a one-piece plastic molded part, for example in an injection molded part.

In a preferred embodiment of the dryer, a stirring device is provided in the bottom pan. This is preferably taken in time overlapping with the vibration generator in operation to assist the cleaning of the water level sensor in addition.

Finally, the dryer can advantageously have a movable wall portion in the bottom tray, as in the DE 10 2006 006 080 A1 is described. By this movable wall portion, an aqueous liquid in the bottom pan can be additionally moved, whereby the cleaning effect is further enhanced in the oscillated water level sensor.

The type and shape of the condensate tray are not limited according to the invention, as long as an aqueous liquid can be collected therein and then suitably removed from the condensate tray.

In a preferred embodiment of the dryer according to the invention, the condensate pan is part of a collecting device for condensate and fluff, which is configured in an upper part as a fluselfepot with a filter that is permeable to an aqueous liquid, but can retain fluff. The term "Flusendepot with a filter" is hereby interpreted broadly. For example, the lint can be designed as a rigid chamber whose bottom is perforated for the passage of an aqueous liquid. In such a rigid chamber may be used as a filter a rigid filter material, e.g. in the form of a perforated sheet metal part or a perforated plastic part may be arranged. In another embodiment, the filter is configured as a sieve or a filter bag, wherein in particular a filled with fluff filter bag can be removed for disposal from the dryer or the rigid chamber. Here, the filter may comprise a fabric, e.g. a fleece. Finally, in another embodiment, the lint can be releasably or permanently connected to the filter. In both embodiments, the lint depot is generally removable from the dryer. In this way, either the river depot can be emptied as such or a filter bag contained in this can be replaced. The filter is also preferably a rigid filter or screen in the last embodiment. The filter may also include a filter cloth held by a rigid support.

In one embodiment, the collecting device has as a lint depot a rigid, open-topped container, in the bottom of which and possibly in its side walls several holes are arranged, through which an aqueous liquid can flow. This container may be lined on its inside with a filter fabric. The holes then serve not a retention of lint, but in particular a good Passage for a cleaned rinsing liquid, eg purified condensate. Such a solution enables a stable support for the filter fabric. Alternatively, the holes may be sized so that the container as such exhibits the desired filtering action.

When using such a collecting device, the extent of contamination of water level sensors in the condensate pan can be further reduced, so that a vibration generator with a relatively low power consumption and / or can be operated for a shorter period.

If there is a lavatory deposit in the dryer, the condensate pan is generally arranged below the lint. This arrangement of the condensate tray below the lint can generally allows an aqueous liquid in the creek deposit to flow through the filter into the condensate tray solely due to the gravitational force. In this embodiment, the condensate tray can be designed as a pure receptacle, which can be removed and emptied at the appropriate time, for example.

In a preferred embodiment of the dryer according to the invention, however, the filtered through the filter aqueous liquid from the tub is passed into a reservoir, which is also referred to herein as a "condensate tank". For this purpose, the trough is preferably connected to the condensate container via a pipe or hose, which is also referred to herein as a "condensate line", and generally a pump, which is referred to herein as a "condensate pump". The condensate container in particular allows a longer storage of the filtered aqueous liquid, for example, for further use in the dryer. If present, the condensate container in the dryer according to the invention serves in particular as a reservoir for an aqueous rinsing liquid as a component of a rinsing device.

The heat source and the heat sink are not limited according to the invention. For example, the heat source may be an electric heater, a fuel heater (gas, oil) or a heat exchanger, in particular a condenser, a heat pump. The dryer according to the invention has a heat sink in which the moist heat Process air is cooled under condensate formation. The heat sink may be, for example, an air-to-air heat exchanger or a heat exchanger, in particular evaporator, a heat pump. If the heat source is an electric heater or a gas or oil heater, an air-to-air heat exchanger is generally used as the heat sink. If a condenser of a heat pump is used as the heat source, the main heat sink is an evaporator of the heat pump.

The invention also relates to a method for operating a dryer with a drying chamber for items to be dried, a process air duct in which a blower for the transport of process air, a heat sink, a heat source and a lint filter are located, a control unit and a water level sensor in one Condensate pan, which is associated with the heat sink for collecting condensate, wherein the water level sensor, a vibration sensor is mounted, and wherein the water level sensor is set in an aqueous liquid by putting the vibrator in motion. In general, the vibrator is moved in a manner and for a period of time sufficient to prevent lint deposits or remove any lint deposits.

The time for carrying out the method according to the invention is not limited. For example, automatically or by a user of the dryer at a desired time, for example after completion of a drying program, the inventive method, which is generally intended to effect a cleaning of the water level sensor, are performed. After completion of a drying program is usually a maximum amount of condensate in the condensate pan, so that for the inventive method to support the cleaning effect of the put into operation vibration generator especially a lot of water is available. However, at the time of finishing a drying program, the deposit of lint on a water level sensor is particularly large. It may therefore be appropriate to carry out the inventive method already at an earlier time.

Alternatively or in addition thereto, a method according to the invention may be carried out depending on the number and / or the extent of drying programs carried out, since the contamination of a water level sensor normally increases with the number and extent of drying programs carried out.

For this purpose, in the dryer, for example, a counter may be present which counts the drying programs carried out, for example the drying programs carried out after a final cleaning of the water level sensor by putting the vibrator into operation. As long as the number of drying programs carried out is low, a comparatively short duration should be sufficient for carrying out the method according to the invention.

In a preferred embodiment, the vibrator is put into operation when there is a movement of an aqueous liquid in the condensate tray. It is preferred that the movement consists in contacting the water level sensor with the aqueous liquid. Alternatively, the movement may be a start-up of a condensate pump, which is generally provided in a dryer for pumping the condensate into a condensate tank.

In a further preferred embodiment, the effect of an aqueous liquid in the bottom pan can be enhanced if, in embodiments of the invention, an agitator is present in the bottom pan.

In addition or as an alternative to this, the aqueous liquid in the condensate tray can be moved in a cycle overlapping in time with the operation of the vibration transmitter. In general, namely the aqueous liquid in the condensate pan, generally condensate, pumped for intermediate storage by means of a condensate pump in a condensate tank. Depending on the dryer can then be provided, for example, that the aqueous liquid is disposed of in the condensate tank by a user of the dryer or automatically. Moreover, and particularly preferably, the liquid collected in the condensate container is used for rinsing purposes in the dryer. For example, the condensate may be used to purge components of the dryer such as the heat exchanger (s) and / or a lint filter.

In a preferred embodiment, it is therefore provided that the aqueous liquid is operated during operation of the vibration generator in the circuit. For this purpose, it may be provided, for example, that the condensate tray is connected to the condensate container both via a condensate line and via a flushing line. The flushing line, which is generally connected to components of the dryer to be cleaned, e.g. A heat exchanger flushing line can then be changed over, for example, such that the flushing line is temporarily connected directly to the condensate pan. Then the water level sensor can additionally be rinsed in the circulation with aqueous liquid during operation of the vibration generator. In this way, relatively much water is available throughout the operation of the vibration generator. On the other hand, if the vibration transmitter is only operated when the condensate is pumped out, the amount of aqueous liquid available for cleaning the water level sensor decreases continuously.

Finally, in embodiments of the method in which the dryer used in the condensate pan has a movable wall portion, as it is for example in the DE 10 2006 006 080 A1 is described, the cleaning effect of the aqueous liquid and the vibration generator are enhanced by the fact that the aqueous liquid is additionally caused by the movement of such a wall portion in motion.

The duration of the process according to the invention is preferably 10 minutes to 20 minutes.

The invention has numerous advantages. Thus, the invention provides a dryer with improved operation, which is improved in particular with regard to safe and error-free operation. For this purpose, the invention enables a better monitoring of a water level in the condensate tray of a dryer. It can be achieved that, for example, one or more water level electrodes always deliver safe signals for detecting the water level. This avoids misinterpretations and false error messages.

The invention makes it possible, in particular, for the time at which a condensate tray to be emptied to be determined with improved accuracy and communicated to a user. In this case, the invention makes it possible that, in the event of failure to observe such instructions, further operation of the dryer prior to emptying the condensate tray and / or cleaning the water level sensor is no longer possible.

• Fig. 1 einen vertikalen Schnitt durch einen Trockner gemäß einer ersten Ausführungsform, wobei der Trockner ein Wärmepumpentrockner ist.
• Fig. 2 einen vertikalen Schnitt durch einen Trockner gemäß einer zweiten Ausführungsform, wobei der Trockner ebenfalls ein Wärmepumpentrockner ist.

Further details of the invention will become apparent from the following description of two embodiments of a dryer according to the invention and a method for operating this dryer. Reference is made to the FIGS. 1 and 2 the attached drawing. Show it:

• Fig. 1 a vertical section through a dryer according to a first embodiment, wherein the dryer is a heat pump dryer.
• Fig. 2 a vertical section through a dryer according to a second embodiment, wherein the dryer is also a heat pump dryer.

The Fig. 1 shows a vertical section through a dryer, which is a heat pump dryer according to a first embodiment, in which the heat source, the condenser 23 and the heat sink, the evaporator 21 of a heat pump 21,22,23,24 compressor type. The vaporized in the evaporator 21 refrigerant of the heat pump 21,22,23,24 is passed through the compressor 24 to the condenser 23. In the condenser 23, the refrigerant liquefies under heat to the process air flowing in the process air duct 4 process air. The now present in liquid refrigerant is passed through the throttle 22 in turn to the evaporator 21, whereby the refrigerant circuit 20 is closed.

The drier 1 comprises a drying chamber 2 (washing drum 2) designed as a rotatable drum, which receives moist laundry items 3. At the in FIG. 1 As shown in the first embodiment, the dryer 1 has a closed process air duct 4 in which, driven by a fan 5, a process air flow is circulated, which absorbs and removes moisture from the laundry items 3. In the condenser 23 of the heat pump as a heat source, the process air before entering the Drying chamber 2 is heated. After the heated process air flows around the laundry items 3 and / or flows through them, it leaves the drying chamber 2 and passes through a lint filter 12 to the evaporator 21 of the heat pump as a heat sink. There, it is cooled, so that the entrained moisture condenses and precipitated as condensate on the evaporator 21 and drips into a arranged below the evaporator 21 collecting device for lint and condensate. This collecting device consists in this embodiment of a river depot 10, which is separated by a filter (Flusendepotfilter 7) from a condensate tray 6 arranged underneath. In the first embodiment shown here is located in the river depot 10, a water level sensor (Flusendepotsensor 34) for determining the presence of an aqueous liquid in the river depot 10, to which not shown here, a vibration sensor, such as a piezoelectric ultrasonic transducer may be attached. The flow depot sensor 34 is also designed as a conductivity sensor in the embodiment shown here.

At the in Fig. 1 shown first embodiment of a dryer according to the invention, the lint filter 12 is cleaned by means of an aqueous liquid (also referred to herein as "rinsing liquid") from a condensate tank 11 via a lint filter cleaning line 35. The rinsing liquid then passes together with rinsed lint first in the lint 10, the filter 7 holds back a majority of lint, and then in the condensate pan 6. The condensate tank 11 is also connected via a condensate line 13 and a condensate pump 14 with the condensate tray 6.

In the dryer 1 of the first embodiment shown here, the condensate tank 11 is additionally connected via a third controllable closure device 30 and a supply line 31 to an external water supply. This allows the additional or alternative use of tap water as rinse water.

The control of dryer 1 via a control unit 18, which can be controlled by the user via a control unit, not shown here, which allows the user of the dryer 1 to select a desired drying program and / or turn on the vibration generator 19. In particular, the control unit 18 can control the implementation of the method according to the invention.

The lint filter 12 generally can not completely absorb the fluff entrained by the process air. A small proportion of finely divided lint will pass through the lint filter 12. These finely divided fluff then settle more or less completely in the evaporator 21, wherein the condensate occurring there promotes adhesion to the inner surface of the evaporator 21. These fluff may affect the function of the evaporator 21. In addition, because of the required complete sealing of the refrigerant circuit 20, a removal of the evaporator 21 from the dryer 1 for the purpose of cleaning is not possible. Therefore, the evaporator 21 is associated with a Wärmesenkenspülvorrichtung 25, which also uses the present in the condensate tank 11 aqueous liquid as a rinsing liquid to rinse the process air exposed surfaces of the evaporator 21 and remove the resulting lint. For this purpose, a flushing line, in this case a heat exchanger flushing line 15, is connected to the condensate tank 11 with a valve 16 arranged therein as a first controllable closing device, which connects the condensate tank 11 to the heat sink flushing device 25. The rinsing liquid laden with lint flows via the flow depot 10 into the condensate tray 6, which here is a bottom tray of the drier. Due to the filtering through the filter 7 only finely divided lint arrive in the condensate tray. 6

In the condensate tray 6, in the embodiment shown here, two electrodes 8 and 9, between which an electrical voltage is applied, are present as water level sensors. The electrodes 8 and 9 are mounted in this embodiment at the bottom of the condensate pan. Upon reaching a predetermined level with water, the electrical conductivity between the electrodes 8 and 9 increases, so that the presence of water between the electrodes is displayed. Between the water level electrodes 8 and 9, a piezoelectric ultrasonic generator 19 with a power consumption of 50 W and an operating frequency of 80 kHz is present as a vibration sensor. To carry out the method according to the invention, the piezoelectric ultrasonic generator 19 is turned on. This can be done automatically at a given time or at the behest of a user of the dryer. In the embodiment shown here, the piezoelectric ultrasonic transducer 19 is connected to the sensor base 26 of each of the two electrodes 8 and 9.

In the case of the dryer 1, the control unit 18 is designed for safety reasons such that when a predetermined maximum filling of the condensate tray 6 has been reached, a drying program can no longer be carried out until the condensate tray 6 has been emptied, for example by pumping off the condensate with the condensate pump 14 ,

The condensate tank 11 is configured in the embodiment shown here so that it can be taken out of the dryer 1, in particular after completion of a drying program to pour the liquid out of him and supply it to a suitable disposal or if necessary to clean it, as a gradual enrichment of extremely finely divided lint or dust in the condensate tank 11 takes place.

The dried process air in the evaporator 21 is further led to a condenser 23 of the heat pump as a heater and passed from there back into the laundry drum 2.

An optical / acoustic display device 17 allows the user of the dryer 1 to display e.g. Operating parameters and / or an expected duration of a drying program. The display device 17 also indicates the implementation of the method according to the invention and in particular the operation of the piezoelectric ultrasonic generator 19.

According to the invention, both the lint filter 12 and the evaporator 21 can be cleaned of lint by being flushed with flushing liquid from the condensate container 11 at the same time or individually. The rinsing liquid can be, for example, fresh water from a water supply of the dryer 1 and / or condensate. The rinsing can be done for example by a rapid emptying when the condensate tank 11 in the dryer 1 is relatively high. The condensate etc. then impinges on the lint filter 12 and / or the evaporator 21 and tears the lint, etc. present there. The then flocculent condensate first enters the Flusendepot 10. The present in the Flusendepot 10 condensate passes through the filter 7, leaving a large part of the lint and can continue to flow to the condensate pump 14, which condensate to a drain, not shown here or back can pump into the condensate tank 11.

In the dryer 1, a method can be performed in which the water level sensors 8 and 9 are set in motion in an aqueous liquid in the condensate tray 6 by putting the piezoelectric ultrasonic generator 19 in motion, so that a deposit of lint prevents or existing deposits of fluff are removed. Here, the ultrasonic generator 19 is put into operation when a movement of an aqueous liquid takes place in the condensate tray 6. The movement consists in contacting the water level sensors 8 and 9 by the aqueous liquid. This is the case when the condensate tray 6 gradually fills with condensate in the course of a drying program and upon reaching a predetermined water level in the condensate tray 6, the electrical conductivity between the water level sensors 8 and 9 increases. The triggering movement can also be a commissioning of the condensate pump 14.

In a drying program, process air is generally circulated repeatedly through the process air duct 4 until preferably a desired degree of drying of the laundry items 3 is achieved.

Fig. 2 shows a vertical section through a dryer according to a second embodiment, wherein the dryer is also a heat pump dryer. In the following, in particular, the differences to those in Fig. 1 shown first embodiment, wherein like reference numerals have the same meaning.

The drier 1 comprises a drying chamber 2 (washing drum 2) designed as a rotatable drum, which receives moist laundry items 3. After the heated process air has flowed around and / or flows through the laundry items 3, it leaves the drying chamber 2 and also passes here via a lint filter 12 to the evaporator 21 of the heat pump as a heat sink. There, the entrained moisture condenses, in particular settles down as condensate on the evaporator 21 and drips into a collecting device for lint and condensate arranged underneath. This collecting device also consists here of a Flusendepot 10, which is separated by a filter (Flusendepotfilter 7) of a condensate tray 6 arranged underneath. In the embodiment shown here, however, there is no water level sensor in the river depot 10. In addition, no rinsing of the lint filter 12 is performed here.

At the in Fig. 2 On the other hand, the condensate container 11 is connected via a second controllable closure device 27, here a flushing water valve designed as a rotary directional valve, on the one hand to the heat sink flushing device 25 and on the other hand to the flow depot 10 or to the condensate pan 6. The rinse water valve 27 can be switched so that rinsing liquid from the Kondensatbehalter 11 passes through the purge line 15 without going through the heat sink rinse device 25 in the condensate pan 6. Then, the operation of the vibration sensor 19, which is also a piezoelectric ultrasonic generator here, supported and improved cleaning of the two water level sensors 8 and 9 can be achieved. In addition, in the condensate tray 6 is a stirring device 29, by means of which a stronger and thus better cleaning flow of the aqueous liquid can be achieved.

In the embodiment shown here, a movable wall section 28 is also present in the condensate pan 6, which can also be set in vibration by means of a vibration generator, not shown here. These vibrations cause additional movement of the aqueous liquid in the condensate tray.

Also in the second embodiment, the condensate tank 11 is additionally connected via a third controllable closure device 30 and a supply line 31 to an external water supply, so that the additional or alternative use of tap water as rinse water is possible.

The two water level sensors 8 and 9 are in the second embodiment of a dryer according to the invention shown here also two electrodes, between which an electrical voltage is applied. In contrast to the first embodiment of Fig. 1 the electrodes 8 and 9 are arranged here in an upper wall 32 of the condensate tray 6, so that they protrude from above into the condensate tray. Upon reaching a predetermined level with water, the electrical conductivity between the electrodes 8 and 9 increases, so that the presence of water between the electrodes is displayed. Between the electrodes 8 and 9 is also a piezoelectric ultrasonic transducer 19 with a power consumption as a vibration generator of 50 W and an operating frequency of 80 kHz available. In the embodiment shown here, the piezoelectric ultrasonic generator 19 is connected to the sensor base 26 of each of the two electrodes 8 and 9, wherein sensor base 26 and the piezoelectric ultrasonic generator 19 are arranged in a one-piece injection-molded plastic molded part 33.

REFERENCE NUMBERS

1

dryer

2

Drying chamber, (laundry) drum

3

laundry

4

Process air duct

5

fan

6

Drain pan; floor pan

7

Filter, Flusendepotfilter

8th

First water level sensor; liquid sensor

9

Second water level sensor; liquid sensor

10

Flusendepot

11

condensate tank

12

lint

13

condensate line

14

condensate pump

15

purge line; Wärmetauscherspülleitung

16

First adjustable closure device; Flush Water

17

optical / acoustic display device

18

control unit

19

Vibration generator, e.g. ultrasonic generator

20

Refrigerant circulation

21

Heat sink, e.g. Evaporator of a heat pump

22

throttle

23

Heat source, e.g. Condenser of a heat pump

24

compressor

25

Wärmesenkenspülvorrichtung

26

sensor socket

27

Second adjustable closure device; Flush Water

28

Mobile wall section

29

agitator

30

Third adjustable closure device; Valve (for external water supply)

31

Supply line for external water supply

32

upper wall of the condensate pan

33

one-piece plastic molding

34

Water level sensor in the river depot

35

Flusenfilterreinigungsleitung

Claims (15)

Dryer (1) with a drying chamber (2) for items to be dried (3), a process air duct (4) in which a blower (5) for the transport of process air, a heat sink (21), a heat source (23) and a lint filter (12), a control unit (18) and a water level sensor (8,9) in a condensate pan (6), which is associated with the heat sink (21) for collecting condensate, characterized in that at the water level sensor (8,9 ) A vibration generator (19) is mounted. Dryer (1) according to claim 1, characterized in that the vibration transmitter (19) comprises an electric motor. Dryer (1) according to claim 1, characterized in that the vibration generator (19) is a piezoelectric ultrasonic generator. Dryer (1) according to one of claims 1 to 3, characterized in that the at least one water level sensor (8,9) is a conductivity sensor and / or an optical sensor. Dryer (1) according to claim 4, characterized in that the at least one water level sensor (8,9) is a conductivity sensor comprising a pair of electrodes, between which an electrical voltage can be applied. Dryer (1) according to one of claims 1 to 5, characterized in that the at least one water level sensor (8,9) is attached to an upper wall (32) of the condensate tray (6). Dryer (1) according to one of claims 1 to 6, characterized in that the vibration sensor (19) on a base (26) of the water level sensor (8,9) is mounted. Dryer (1) according to one of claims 1 to 7, characterized in that the power consumption of the vibration generator (19) is in the range of 20 W to 80 W. Dryer (1) according to one of claims 1 to 8, characterized in that the oscillation frequency of the vibration generator (19) is in the range of 50 kHz to 100 kHz. Dryer (1) according to one of claims 1 to 9, characterized in that the dryer (1) has an optical and / or acoustic display device (17), which carries out the cleaning of the at least one water level sensor (8,9) by the operation of the vibrator (19) indicates. Dryer (1) according to one of claims 1 to 10, characterized in that the at least one water level sensor (8,9) and the vibration generator (19) are arranged in a one-piece plastic molded part (33). Method for operating a dryer (1) with a drying chamber (2) for items to be dried (3), a process air channel (4) containing a blower (5) for conveying process air, a heat sink (21), a heat source (23) and a lint filter (12), a control unit (18) and a water level sensor (8,9) in a condensate pan (6), which is associated with the heat sink (21) for collecting condensate, wherein at the water level sensor (8, 9) a vibration transmitter (19) is mounted,
characterized in that the water level sensor (8,9) is set in motion in an aqueous liquid by putting the vibrator (19) into operation. A method according to claim 12, characterized in that the vibration generator (19) is put into operation when a movement of an aqueous liquid in the condensate tray (6) takes place. A method according to claim 13, characterized in that the movement in a contact of the water level sensor (8,9,34) consists of the aqueous liquid. Method (1) according to claim 13, characterized in that the movement is a commissioning of a condensate pump (14).

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