EP3246457A1 - Tumble dryer - Google Patents

Abstract

The present invention relates to a tumble dryer (1), and associated methods for drying laundry, with a laundry drum (15) for receiving laundry to be dried and a heat pump unit (3) for generating process air for drying the laundry in the laundry drum (15). The tumble dryer (1) is characterized by at least one contactless heating unit (2), which is designed and arranged to heat the laundry drum (15) without contact.

Description

The present invention relates to a tumble dryer according to the preamble of claim 1 and to a method for drying laundry by means of such a tumble dryer according to claims 11 to 13.

• Zum einen ist es bekannt, die Trommel eines Wäschetrockners mittels eines elektrischen Widerstandsheizelements direkt zu erwärmen. Beispielsweise beschreibt die DE 43 13 538 A1 eine Einrichtung zum Trocknen von Textilgut in Wäschetrocknertrommeln. Um die Wärmezufuhr von der Heizung zu dem zu trocknenden Textilgut auf möglichst direktem Weg zu bewirken, werden ein oder mehrere elektrische Widerstandsheizelemente an der Außen- oder Innenfläche des Trommelmantels angeordnet und mit diesem fest verbunden. Hierdurch soll der Wirkungsgrad beim Wäschetrocknen verbessert werden.

For drying laundry laundry dryers are usually used. These heat the laundry to be dried and thus deprive it of moisture. For this purpose, various physical principles are known to bring about this heating of the laundry to be dried:

• On the one hand, it is known to directly heat the drum of a tumble dryer by means of an electrical resistance heating element. For example, this describes DE 43 13 538 A1 a device for drying textiles in tumble dryer drums. In order to effect the supply of heat from the heater to the textile material to be dried as directly as possible, one or more electrical resistance heating elements are arranged on the outer or inner surface of the drum shell and firmly connected to this. This is intended to improve the efficiency of laundry drying.

The disadvantage here is that an electrical connection to the electrical resistance heating must be made, which rotate with the drum. This can e.g. be achieved by brush contacts, but this is expensive and therefore expensive. Furthermore, the brush contacts are subject to significant wear, so that the life of such solutions of the electrical contact between mutually moving contact partner is limited. This can lead to increased maintenance and repair costs of such clothes dryers.

A further disadvantage is that the heat generation takes place directly with electric current, which can lead to a high power consumption of such dryers with electric heating. This leads to an inefficient type of laundry drying, which today may be highly undesirable against the background of rising electricity costs and from the perspective of environmental impact.

Alternatively, heat pump tumble driers are known. These have a closed heat pump cycle with a compressor, an evaporator, a condenser and a capillary. Through this heat pump cycle the process air moisture is removed, which was previously removed from the laundry. For this purpose, the previously heated by the heat pump cycle and dehumidified process air is passed through a fan through an air supply duct in a laundry drum of the tumble dryer. In the laundry drum, the laundry to be dried is usually moved by rotation, so that the process air can reach the laundry as completely and uniformly as possible.

The heated process air absorbs moisture from the laundry and dries it. The moist process air then returns via an air return channel to the heat pump cycle. Here, the moisture extracted from the laundry is condensed from the process air and discharged in liquid form to the outside. The energy extracted from the process air is returned to the process air so that the process air, once heated, leaves the heat pump cycle in the direction of the laundry drum. The cycle of process air is closed in this way. Examples of heat pump tumble dryer provide the EP 2 642 018 A2 and the DE 42 12 700 A1 represents.

In other words, a heat pump tumble dryer is a condensation dryer that heats the process air by convection. The process air heats the laundry by convection and evaporates the water. The moist warm air is then dehumidified and cooled in the air condenser (heat pump evaporator). It must be ensured that in the designed heat pump cycle before entering the compressor overheating is ensured, i. The compressor should only draw in dry steam and not a two-phase mixture as this would cause the compressor to fail.

The condition of the refrigerant is heavily dependent on pressure and temperature. These two parameters and thus the entire heat transfer process are decisively influenced by the enthalpy flow of the process air and the onset of condensation on the heat transfer surface of the air condenser. This means that process management is necessary for the shortest possible drying time, which increases the enthalpy flow of the process air, adapts it to the operating range of the heat pump, ensures overheating and allows as much water as possible to condense out of the process air.

Although heat pump tumble dryers are significantly more energy efficient than tumble dryers with electrical resistance heating elements, they have a much lower temperature range, which can be achieved by means of the heat pump. This can lead to significantly longer drying times.

Furthermore, induction dryers are known. This type of heating uses the principle of the transformer. Flat copper coils are usually provided, through which an alternating current with frequencies between 20 kHz and 100 kHz can flow. The current flow creates a primary magnetic field around the tightly wound coil, which constantly changes direction in response to the changing sign of the current. If a ferromagnetic material is within the range of action of this magnetic field, the high-frequency primary alternating magnetic field passes through this material and induces surges and thus eddy currents. These enclose the magnetic field in a ring shape and in turn cause a secondary magnetic field.

The secondary magnetic field counteracts (flux displacement) the changes in the magnetic flux of the primary magnetic field, especially in the interior of the ferromagnetic material, such that the primary magnetic field can only penetrate into the surface of the ferromagnetic material. As a result, the eddy currents induced by the primary magnetic field do not uniformly pass through the ferromagnetic material, but merely flow in a thin boundary layer. The property of high-frequency eddy currents to flow only in the "skin" of a conductor (skin effect) means that the effectively used line cross-section is reduced. This increases the resistance of the conductor so that the eddy currents in the surface layer generate enough Joule heat to directly heat the ferromagnetic material.

In addition, another important phenomenon contributes to the heating of the ferromagnetic material. Because the magnetic field aligns the electron spins in the ferromagnetic material as elementary magnetic moments. However, this magnetization is not completely reversible when the external magnetic field changes direction in time with the AC frequency, i. the magnetization resists this rapid change. This creates friction in the material and some of the electromagnetic energy that must be expended during each magnetization reverses into heat (hysteresis losses). These heat losses in the ferromagnetic material can contribute about one third of the heating power of the induction.

The EP 2 400 052 A1 concerns, inter alia, a dryer in which an induction heating system is used to heat the air. The drum of the dryer has a heating coil of conductive material disposed around the drum. The heating coil is electrically contacted and supplied from outside such that the heating coil is an electromagnetic Field can produce, which act on the drum and this can heat inductively.

The disadvantage here is that even in this case an electrical connection to the electrical heating elements is to be made, which rotate with the drum, see above. This can lead to increased maintenance and repair costs of such clothes dryers.

The US 4,181,846 A relates to a rotary heating device which operates with induction. A rotating drum has at least partially a material which can be heated by means of magnetic induction. An induction heating coil is located close enough to this part of the rotating drum to heat that part of the drum during operation. The drum can be rotated by a motor. During operation, the interior of the drum can be heated by means of heat radiation and heat conduction emanating from the inductively heated drum. The JP 2004 135 998 A shows a comparable dryer.

The disadvantage here is that the heat within the drum only emanates from the heated drum. This can lead to a very uneven heat distribution within the drum. This may be the case in particular if a lot of laundry is applied to the inside of the drum and this shields thermally against the air inside the drum.

JPH06-121898 A relates to a comparable induction dryer in which, however, a fan is disposed on the axis of rotation of the drum to produce a flow of air centrally through the inductively heated drum. This air flow is simultaneously guided past the induction heating coil and its converter in order to use their waste heat to heat the air flow. As a result, a more uniform heating of the interior of the drum is to be achieved.

The disadvantage here is that only waste heat for heating the air can be used, which can not have much effect. Furthermore, this heat is available only after a certain period of operation of the induction dryer, if already the drying of the laundry was already at least partially carried out. Furthermore, the inductively generated heat and the waste air generated warm air are related because both are generated by the induction heating coil and its inverter.

In addition, it is e.g. The company Arcelik, LG and Whirlpool known to provide an additional electrical resistance heating in a heat pump tumble dryer, which can increase the temperature of the process air and thereby shorten the drying times, while the principle of heat pump drying can be used with its advantages at least partially.

The disadvantage here, however, that the heat pump cycle can reach a non-permissible operating point due to high compressor pressures, which can lead to a total loss of the device. To prevent this, additional components such as e.g. a regulated expansion valve necessary, but this means an extra effort and additional costs.

Another disadvantage is that the electrical resistance heater is an ignition source and can reach temperatures above 350 ° C. Thus, an electrical resistance heater can not be used in combination with alternative refrigerants, e.g. R270 (propane) without additional safety measures being taken in this case. However, this also means additional effort and additional costs.

An object of the present invention is to provide a tumble dryer of the type described above, which at the same time has a lower drying time than conventional tumble dryer with the greatest possible energy efficiency. In particular, such a tumble dryer should be created based on a heat pump tumble dryer without changing its heat pump system. Overall, alternatively and / or improved possibilities for drying as well as the hot airing of laundry by means of a tumble dryer should be provided.

The object is achieved by the features of the characterizing part of claim 1 and by the features of claims 11 to 13. Advantageous developments are described in the subclaims.

The present invention thus relates to a tumble dryer with a laundry drum for receiving laundry to be dried and with a heat pump unit for generating process air for drying the laundry in the laundry drum. The tumble dryer can therefore also be referred to as a heat pump tumble dryer. Although such dryers are characterized by their high energy efficiency, but have a relatively low temperature range, which can be achieved by means of the heat pump. This can lead to significantly longer drying times. This can affect customer acceptance despite lower energy consumption.

The tumble dryer according to the invention is therefore characterized by at least one contactless heating unit, which is designed and arranged to heat the laundry drum contactlessly. Non-contact heating units are all physical principles which are able to bring about heating of the laundry drum without having any contact with the laundry drum, i. without touching the laundry drum. This can be for example a heating by means of induction or by means of infrared radiation. The contactless heating of the laundry drum thereby made possible can be done additionally or alternatively to the drying of the laundry in the laundry drum by means of the process air of the heat pump unit of the tumble dryer.

The advantage here is that the laundry drum itself can be heated by the additional heating by means of the contactless heating unit, so that the laundry in the laundry drum can be heated and dried from radially inside through the process air of the heat pump unit and from the outside radially through the non-contact heated laundry drum. This can lead to an improvement in the evaporation of moisture in the laundry to be dried and thus to an improvement in the condensation of the washing machine. As a result, a faster drying and thus a reduction of the drying time can be achieved.

In other words, a multiple of the enthalpy flow introduced by the forced convection by means of the process air for the evaporation of the water in the laundry to be dried can be provided by the heat conduction of the contactless heated laundry drum. In this way, a tumble dryer can be made available, which provides not only with forced convection the enthalpy of vaporization, but in addition by the heat conduction of the contactless heated laundry drum. By heating the laundry drum, the heat pump can be significantly more efficient, since the heat pump no longer has to compensate for the losses to the environment.

Thus, the heat conduction of the contactless heated laundry drum and the convection of the process air complement each other in the process. Energy is transferred to the laundry via the heat conduction, whereby the delta of the phase change enthalpy from the process volumetric flow for the evaporation is reduced. This can make more water out to evaporate the laundry to be dried and be removed from this. At the same time, the process air is not cooled down so much and can absorb more water. This leads to a significant increase in Enthalpiemassenstroms from the laundry drum. The compressor is thereby more efficient, because due to the larger Enthalpiestroms greater overheating in the refrigerant circuit and thus a higher density in the refrigerant compared to a heat pump tumble dryer without additional contactless heating of the laundry drum adjusts. At the same time significantly more water is condensed out of the process air, since the heat transfer of the evaporator of the heat pump is more efficient due to the higher temperature and the water stored therein. As a result, the drying process or the condensation can be significantly improved. The advantage here is that this acceleration of drying can be implemented without a change in the heat pump unit and without affecting the drying programs in an existing heat pump tumble dryer. This can minimize the cost of implementing this improvement and increase customer acceptance.

A further advantage is that the additional contactless heating unit can be provided as an additional module, so that this function of the additional contactless heating of the laundry drum can be offered and provided as an option existing heat pump tumble dryer.

It is also advantageous that no noise is generated by this additional contactless heating of the laundry drum, which could disturb the user and reduce the acceptance of such a tumble dryer.

A further advantage is that the additional non-contact heating unit can also be used in heat pump tumble dryer, in which propane is to be used as refrigerants.

It is also advantageous that a faster heating of the laundry drum can be achieved by the contactless heating of the laundry drum, which can lead to a lower crease of the laundry to be dried. Because of the significantly shorter drying times, the mechanical load on the laundry can be reduced because the items of laundry rub against one another for a shorter time, which otherwise can lead to a load on the fibers of the items of laundry due to abrasion. Also, the faster drying of the water can be transported faster from the fibers of the laundry, whereby the net weight of the laundry to be dried fall and thus the friction between the laundry items can also be reduced. Preferably, the laundry drum can be heated to the desired drying temperature of the laundry to start drying and operated at this temperature, the process air has reached its predetermined temperature. This too may favor the reduction of creasing.

In other words, a gentle drum for a heat pump tumble dryer can be created by the non-contact heating unit, since the creasing of the typical long heating phase at low temperatures and cold wall of the laundry drum of the previously known heat pump tumble dryer can be prevented.

It is also advantageous in the gentle or wrinkle-reduced drying of the laundry that, as a result, the formation of fibers and lint in the process air can also be reduced, which must be removed from the process air by means of filters. These filters need to be cleaned less frequently, which can relieve the user.

According to one aspect of the present invention, the non-contact heating unit is arranged to be fixed radially outside the laundry drum. In this case, the non-contact heating unit can be arranged, for example, at a radial distance from the laundry drum of preferably up to 2.5 cm in order to maintain a sufficient distance, so that even during operation safe touches can be avoided, but at the same time can be done an efficient heating of the laundry drum. The fixed arrangement of the contactless heating unit, a simple electrical supply can be achieved. Furthermore, a secure and permanently durable positioning and alignment with respect to the rotatable laundry drum can be achieved.

It is advantageous here that no changes in the guidance of the process air are required by the additional contactless heating unit in this case, so that the contactless heating unit can be easily supplemented with existing heat pump tumble dryers. In particular, due to the additional contactless heating unit, there are no bypasses or flow resistances in the guidance of the process air, so that the heat pump unit as well as the guidance and use of the process air can not be changed.

The non-contact heating unit can be arranged, for example, at the top or bottom in one of the corners of the housing of the tumble dryer, where, in addition to the cylindrical laundry drum, there is usually sufficient space for an additional contactless heating unit. The However, contactless heating unit can also be arranged integrated, for example, on the condensation tank housing, on a side wall or in another component.

According to another aspect of the present invention, the non-contact heating unit is an induction heating unit. This may comprise one or more coils, which may be supplied with a high-frequency alternating current, to induce an inductive heating by means of a primary magnetic field in the radially outer layer of the material of the laundry drum. The laundry drum is for this purpose preferably formed from a ferromagnetic material or has at least partially on a ferromagnetic material.

It is advantageous here that the use of inductive heating in washing machines and dryers is basically known and tested in practice, so that a safe technique can be used here. This can lead to a high level of customer acceptance for this type of additional heating.

It is also advantageous that the heating effect on ferromagnetic materials in the after-range of the induction heating unit can be limited, so that unwanted effects on other elements within the tumble dryer can be avoided.

According to another aspect of the present invention, the non-contact heating unit is configured to operate only when the laundry drum is rotating. This is to ensure that it does not come to an inadmissible high heating of the laundry drum or sections herebefore and thus of laundry or partial areas of laundry, which rest on the inside of the laundry drum. Furthermore, it is advantageous to operate the contactless heating unit only when the laundry drum is rotating in order to achieve a uniform temperature distribution on the wall of the laundry drum and in the laundry to be dried.

In other words, the contactless heating unit heats only when the speed of the laundry drum is greater than zero, to prevent local overheating of the laundry drum and to heat the laundry to be dried evenly. Due to the uniform and rapid heating of the laundry drum, the laundry for a not cooled as previously through the wall of the laundry drum but there heated, so that the laundry can be dried faster and can form no creases in the laundry.

According to a further aspect of the present invention, the laundry drum is designed to be operated at a speed which is as high as possible but low enough to prevent the laundry from being placed against the interior of the laundry drum. In other words, the laundry drum should be operated as fast as possible, however, below the contact speed.

In order to achieve a uniform heating of the laundry items and the evaporation of the water, it should be avoided that the laundry to be dried remains permanently on the wall of the laundry drum. In other words, no reaction speed should be run in the process. For this, a speed range between -80 rpm <n <80 rpm must be observed. In this case, the items of laundry can be heated via the heat conduction of the contactless heated laundry drum and the process air of the heat pump unit. Preferably, the laundry drum is rotated during operation with a rotational rhythm between 10 U / min and 70 U / min. In this speed range, the uniform heating of the load can be ensured.

In the course of one revolution of the laundry drum, the laundry items to be dried detach from the laundry drum due to gravity, so that the surface of the laundry drum is impinged by the process air, the water evaporates there and then in the enthalpy stream from the laundry drum to the condenser (heat pump evaporator). can be forwarded. The laundry items not streamed by the process air volume flow and applied to the wall of the laundry drum are deliberately heated by means of the heat conduction of the laundry drum, which are cooled by the wall of the laundry drum without the heating of the laundry drum or at best retain their temperature. As a result, an improved drying performance can be achieved, which can lead to improved efficiency of the tumble dryer and shorter drying times.

It is advantageous, however, to select the highest possible speed of the laundry drum below the contact speed, so that the laundry to be dried as long as possible rests against the heated laundry drum and can be done by this long contact time as good as possible heat conduction. Furthermore, this allows a greater drop height and thus a larger fall path can be achieved so that the laundry as completely as possible and as long as the process air can be suspended. This can lead to a larger volume flow of the process air.

According to another aspect of the present invention, the non-contact heating unit is configured to be operated with adjustable heating power. Power outputs by the non-contact heating unit in the range of 600 W, 1200 W and 1,800 W can preferably be used. Preferably, the non-contact heating unit controls the temperature of the laundry drum in a range between 40 ° C to 130 ° C. In this case, a very accurate control of the temperature of the laundry drum is preferably possible.

According to a further aspect of the present invention, the non-contact heating unit is formed, with a heating power depending on the speed of the laundry drum, Residual fencing of the laundry, ambient temperature, power or speed of the compressor, load volume dependent, refrigerant temperature dependent, program type dependent or load type, motor and fan power dependent, process air volume flow dependent or Filterfüllgrad, compressor fan state or speed, loading temperature to be operated. In this way, the heating power can be optimized by e.g. it is ensured that the highest possible speed of the laundry drum driven, but this is below the contact speed. At the same time, the temperature of the laundry drum can be set as high as possible in order to achieve the highest possible heat conduction. At the same time, the temperature of the laundry drum should be kept low enough not to damage the items to be dried. In this case, the temperature of the laundry drum via the contactless heating unit can be adapted to these requirements in order to achieve an optimum result. Therefore, the speed of the laundry drum decreases, so the performance of the contactless heating unit can be adjusted.

According to a further aspect of the present invention, the contactless heating unit is designed to be operated with a heating power as a function of the temperature of the process air. In this way, the interaction between heat generation by heat conduction of the contactless heated laundry drum and by heat convection of the process air flow can be adjusted to each other in order to achieve an optimal Enthalpiestrom. Also, the contactless heating unit can be used, for example, only at the beginning of the operation of the tumble dryer until the process air has reached its intended temperature. This can lead to an acceleration of the drying process, but still takes place essentially via the heat pump unit.

According to a further aspect of the present invention, the contactless heating unit is designed to be operated with a heating power as a function of the duration of the current operation. As a result, the performance of the contactless heating unit or its operation at all depending on the operating time of the respective use of the clothes dryer. In this way, for example, the contactless heating unit can be switched off after a certain period of the current operation or at least reduced in performance. Likewise, the contactless heating unit can be switched on only at a later time of the current operation.

According to another aspect of the present invention, the laundry drum has insulation on its radially outer side. This insulation is preferably non-magnetic as much as possible, i. has the lowest possible magnetic permeability, so that the insulation of a primary magnetic field of a high-frequency alternating current for the purpose of inductive heating of the laundry drum can be penetrated as well as possible and completely. Preferably, the insulation has the lowest possible thermal conductivity in order to prevent the inductively generated heat of the laundry drum from escaping as far as possible radially to the outside. As a result, the heat generated without contact can be emitted as completely as possible radially inward toward the laundry to be dried, which can increase the efficiency of the contactless heating element.

Preferably, the clothes dryer according to the present invention comprises a laundry drum formed in material and construction for use with a non-contact induction heating unit. For this purpose, a thermal suction drum may be formed as an induction drum, the insulation is formed as described above.

• Starten der Drehung der Wäschetrommel, und
• zeitlich hiernach, im Wesentlichen gleichzeitiges Starten des Betriebes der kontaktlosen Heizeinheit und der Wärmepumpeneinheit.

The present invention also relates to a method for drying laundry by means of a tumble dryer as described above with the steps:

• Start the rotation of the laundry drum, and
• temporally thereafter, substantially simultaneously starting the operation of the non-contact heating unit and the heat pump unit.

In other words, first the rotation of the laundry drum is started to bring the laundry in motion and to avoid excessive heating of individual laundry items by the heat conduction of the laundry drum. Then, both the contactless heating unit and the heat pump unit are started substantially simultaneously. By "temporally hereafter" is meant a sufficient temporal offset, which differs from "substantially simultaneously", and vice versa.

In this way, both types of drying can be used together and preferably from the beginning of the drying operation after starting the rotation of the laundry drum.

The advantages of this type of drying have already been described above. Thus, by using the preferably induction heating in combination with a heat pump in a preferred speed range of the laundry drum of greater than zero and between -80 U / min <n <80 U / min, in particular between 10 U / min and 70 U / min, the Evaporation and condensation are significantly improved over known heat pump tumble dryers, which can reduce drying time and increase efficiency.

• Starten der Drehung der Wäschetrommel,
• zeitlich hiernach oder parallel, Starten des Betriebes der kontaktlosen Heizeinheit, und
• zeitlich hiernach oder parallel, Starten des Betriebes der Wärmepumpeneinheit.

The present invention also relates to a method for drying laundry by means of a tumble dryer as described above with the steps:

• Starting the rotation of the laundry drum,
• time after or in parallel, starting the operation of the non-contact heating unit, and
• temporally after or in parallel, starting the operation of the heat pump unit.

This can be started with the drying of the laundry in the laundry drum by means of the heat transfer of the heated laundry drum, while the heat pump unit starts up its temperature up to a predetermined temperature of the process air. In this way, the total drying time can be shortened. Furthermore, this can prevent wrinkles by setting a saving temperature of the laundry drum during this time, in which the non-contact heating unit is operated alone.

• Starten der Drehung der Wäschetrommel, und
• zeitlich hiernach, Starten des Betriebes der kontaktlosen Heizeinheit.

The present invention also relates to a method for drying laundry by means of a tumble dryer as described above with the steps:

• Start the rotation of the laundry drum, and
• after that, start the operation of the contactless heating unit.

In other words, in this case, only the non-contact heating unit is operated while the laundry drum is rotating, but dispenses with the use of the heat pump unit. As a result, for example, a pure warm airing of the laundry can be done without drying them. Offering such a program through the use of a heat pump unit would result in a long duration of the program, which may prevent customer acceptance. With a pure heat conduction through the contactless heated laundry drum, however, this function can be provided quickly, so that a customer could make use of this possibility. As a result, known heat pump tumble dryer could be extended by an attractive program option.

Furthermore, quick and easy drying options for items of laundry can be provided in this way, which require only a slight drying. This can e.g. Be shirts or jeans. Also in this case, the heat pump can remain switched off and the drying can be done exclusively for the heat conduction of the contactless heated laundry drum. The cold heat transfer surfaces of the heat pump unit can be sufficient to condense the low residual moisture.

• Beenden des Betriebes der kontaktlosen Heizeinheit bei weiterhin Betreiben der Wärmepumpeneinheit, oder
• Beenden des Betriebes der Wärmepumpeneinheit bei weiterhin Betreiben der kontaktlosen Heizeinheit.

According to another aspect of the present invention, the method further comprises the further step:

• Terminating the operation of the non-contact heating unit while continuing to operate the heat pump unit, or
• Terminating the operation of the heat pump unit while continuing to operate the non-contact heating unit.

In this way, only one of the two heat sources can be operated individually. For example, the contactless heating unit can be turned off as soon as the heat pump unit has reached its operating temperature.

According to a further aspect of the present invention, the laundry drum is operated at a speed which is as high as possible, but low enough, in order to prevent a concern of the laundry on the interior of the laundry drum. The advantages brought about by this have already been explained before and should not be repeated here.

Fig. 1a

eine perspektivische schematische Darstellung eines erfindungsgemäßen Wäschetrockners gemäß einer ersten Ausführungsform;

Fig. 1b

die Darstellung der Fig. 1a im Schnitt von oben;

Fig. 1c

die Darstellung der Fig. 1a im Teilschnitt von vorne;

Fig. 2a

eine perspektivische schematische Darstellung eines erfindungsgemäßen Wäschetrockners gemäß einer zweiten Ausführungsform;

Fig. 2b

die Darstellung der Fig. 2a im Schnitt von der rechten Seite;

Fig. 3a

eine perspektivische schematische Darstellung eines erfindungsgemäßen Wäschetrockners gemäß einer dritten Ausführungsform; und

Fig. 3b

die Darstellung der Fig. 3a im Schnitt von der linken Seite.

Several embodiments and further advantages of the invention will be explained below in connection with the following figures. It shows:

Fig. 1a

a perspective schematic view of a laundry dryer according to the invention according to a first embodiment;

Fig. 1b

the representation of Fig. 1a in section from above;

Fig. 1c

the representation of Fig. 1a in partial section from the front;

Fig. 2a

a perspective schematic representation of a laundry dryer according to the invention according to a second embodiment;

Fig. 2b

the representation of Fig. 2a in section from the right side;

Fig. 3a

a perspective schematic view of a laundry dryer according to the invention according to a third embodiment; and

Fig. 3b

the representation of Fig. 3a in the section from the left side.

Fig. 1a shows a perspective schematic representation of a laundry dryer 1 according to the invention according to a first embodiment. Fig. 1b shows the representation of Fig. 1a in section from above. Fig. 1c shows the representation of Fig. 1a in partial section from the front. The tumble dryer 1 extends at a height Z, a depth X and a width Y.

The tumble dryer 1 has a front 10, a right side 11, a left side 12, a back 13 and a top 14, wherein in the illustration of Fig. 1a and 1b the top 14 is omitted to make the interior of the clothes dryer 1 at least partially visible. Inside the tumble dryer 1, a cylindrical laundry drum 15 is arranged, which can rotate about an axis of rotation A. From the axis of rotation A, the radial direction R shows away, see for example Fig. 1 b. The laundry drum 15 can be filled from the front 10 of the clothes dryer 1 by a laundry door 16 with laundry to be dried.

The tumble dryer 1 has a heat pump unit 3, which is arranged below the laundry drum 15, see for example Fig. 2a to 3b , From the heat pump unit 3, heated process air via a process air inlet 17, see, for example Fig. 1c be introduced into the laundry drum 15 to dry the laundry located there. The process air can then via a process air outlet 18, see eg Fig. 1a be returned to the heat pump unit 3 again.

Such clothes dryers 1 are known as heat pump clothes dryer 1 from the prior art. Although heat pump tumble driers 1 are significantly more energy-efficient than other tumble dryers 1, they have a significantly lower temperature range, which can be achieved by means of the heat pump unit 3. This can lead to significantly longer drying times. This can reduce customer acceptance for such clothes dryers 1.

According to the invention, the clothes dryer 1 of the present patent application therefore has an additional contactless heating unit 2, which is provided in the considered embodiments in the form of an induction heating unit 2 with two induction heating elements 20 in the form of induction coils 20 and a power electronics which is connected to the coil (this is not to be seen in the pictures). The laundry drum 15 is correspondingly formed from a ferromagnetic material. The induction heating unit 2 is located in the upper right corner of the interior of the tumble dryer 1, so that the space available there can be used. Further, the induction heating unit 2 is easily and quickly accessible at this position by removing the cover of the top 14 both during assembly and for maintenance or repair.

In this way, inductive heating of the laundry drum 15 by the induction heating unit 2 can take place. In order to supply the heat generated in this way to the induction heating unit 2 as completely as possible to the interior of the laundry drum 15, the laundry drum 15 has an insulation 19 radially on the outside, which is designed to be magnetically permeable and thermally insulating. This is intended to be achieved or favored that the heat generated inductively in the laundry drum 15 is not as possible dissipated to the outside but is used to heat the laundry to be dried by means of heat conduction.

According to the invention, the washing drum 15 can be heated in this way in order to dry the laundry resting thereon by means of heat conduction. In addition, the laundry can be dried as previously known by the process air of the heat pump unit 3. As a result, on the one hand, the drying time can be shortened. On the other hand, the efficiency of the tumble dryer 1 can be increased by an increased Enthalpiestrom. There are various combinations of the operation of the two heat sources, i. the induction heating unit 2 and the heat pump unit 3, possible to achieve the optimum result according to various criteria such as the shortest possible drying time, the lowest possible energy consumption, as gentle as possible drying for different types of laundry or moisture levels of the laundry.

Fig. 2a shows a perspective schematic representation of a laundry dryer 1 according to the invention according to a second embodiment. Fig. 2b shows the representation of Fig. 2a in the section from the right side. In this embodiment, the induction heating unit 2 is arranged on the bottom right, so that this space could also be used for the induction heating unit 2.

Fig. 3a shows a perspective schematic representation of a laundry dryer 1 according to the invention according to a third embodiment. Fig. 3b shows the representation of Fig. 3a in the section from the left side. In this embodiment, the induction heating unit 2 is arranged at the bottom left, so that this space could be used for the induction heating unit 2.

LIST OF REFERENCE NUMBERS

A

Rotation axis of the laundry drum 15th

R

radial direction

X

Longitudinal direction, depth

Y

Transverse direction, width

Z

height

1

clothes dryer

10

front

11

right side

12

left side

13

back

14

top

15

washing drum

16

Washing drum door

17

Process air inlet of the laundry drum 15

18

Process air outlet of the laundry drum 15

19

External insulation of the laundry drum 15th

2

contactless heating unit, induction heating unit, infrared heating unit

20

induction heating elements

3

heat pump unit

Claims (15)

Clothes dryer (1), with
a laundry drum (15) for receiving laundry to be dried, and
a heat pump unit (3) for generating process air for drying the laundry in the laundry drum (15),
marked by
at least one contactless heating unit (2), which is designed and arranged to heat the laundry drum (15) without contact. Clothes dryer (1) according to claim 1,
wherein the non-contact heating unit (2) is arranged fixed radially outside the laundry drum (15). Clothes dryer (1) according to claim 1 or 2,
wherein the non-contact heating unit (2) is an induction heating unit (2). Clothes dryer (1) according to one of the preceding claims,
wherein the non-contact heating unit (2) is adapted to be operated only when the laundry drum (15) is rotating. Clothes dryer (1) according to one of the preceding claims,
wherein the laundry drum (15) is adapted to be operated at a speed which is as high as possible, but low enough to prevent the laundry from contacting the interior of the laundry drum (15). Clothes dryer (1) according to one of the preceding claims,
wherein the non-contact heating unit (2) is designed to be operated with adjustable heating power. Clothes dryer (1) according to one of the preceding claims,
wherein the non-contact heating unit (2) is designed to be operated with a heating power as a function of the rotational speed of the laundry drum (15). Clothes dryer (1) according to one of the preceding claims,
wherein the contactless heating unit (2) is formed, with a heating power as a function of the temperature of the process air, residual fights of the laundry, Ambient temperature, power or speed of the compressor, load volume dependent, refrigerant temperature dependent, program type dependent or load type, motor and blower power dependent, process air volume flow dependent or filter fill level, compressor fan state or speed, load temperature to be operated. Clothes dryer (1) according to one of the preceding claims,
wherein the contactless heating unit (2) is designed to be operated with a heating power as a function of the duration of the current operation. Clothes dryer (1) according to one of the preceding claims,
wherein the laundry drum (15) has on its radial outer side an insulation (19). Process for drying laundry by means of a tumble dryer (1) according to one of claims 1 to 10, comprising the steps: Start the rotation of the laundry drum (15), and temporally thereafter, substantially simultaneously starting the operation of the non-contact heating unit (2) and the heat pump unit (3). Process for drying laundry by means of a tumble dryer (1) according to one of claims 1 to 10, comprising the steps: Starting the rotation of the laundry drum (15), time after or in parallel, starting the operation of the non-contact heating unit (2), and time after or in parallel, starting the operation of the heat pump unit (3). Process for drying laundry by means of a tumble dryer (1) according to one of claims 1 to 10, comprising the steps: Start the rotation of the laundry drum (15), and after that, start the operation of the contactless heating unit (2). Method according to one of claims 11 to 13, with the further step: Terminating the operation of the contactless heating unit (2) while continuing to operate the heat pump unit (3), or Terminating the operation of the heat pump unit (3) while continuing to operate the non-contact heating unit (2). Method according to one of claims 11 to 14,
wherein the laundry drum (15) is operated at a speed which is as high as possible but low enough to prevent a concern of the laundry on the interior of the laundry drum (15).

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