A tumble dryer with a heat pump system

Abstract

 The present invention relates to a tumble dryer with at least one heat pump system. The tumble dryer comprises an air stream circuit (10) including at least one drum (12) for receiving laundry to be dried and at least one fan (24) for generating an air stream, at least one refrigerant circuit (14) including at least one compressor (16), a first heat exchanger (18) for a thermal coupling between the air stream circuit (10) and the refrigerant circuit (14), a second heat exchanger (20) for a further thermal coupling between the air stream circuit (10) and the refrigerant circuit (14), and at least one electric motor for driving the drum (12), the compressor (16) and/or the fan (24). At least one electric and/or electronic control circuit (22) for controlling the electric motor is at least partially arranged within the air stream circuit (10).

Description

[0001] The present invention relates to a tumble dryer with a heat pump system according to the preamble of claim 1.

[0002] In a tumble dryer the heat pump technology is an efficient way to save energy. A usual tumble dryer with heat pump technology uses a refrigerant circuit. The refrigerant is compressed and heated by a compressor. The refrigerant is cooled down in a heat exchanger, in which an air stream for the air stream circuit is heated up. Then the air stream reaches the drum with the laundry. The air stream leaves the drum with a decreased temperature and an increased humidity. In a further heat exchanger the air stream is cooled down and dehydrated and the refrigerant is heated up, wherein the refrigerant has passed an expansion valve before. In said further heat exchanger the water vapour condenses. Then the refrigerant is compressed and heated again by the compressor. Thus, a part of the energy can be recovered.

[0003] EP 2 063 011 A1 discloses a household appliance like a washing machine or a tumble dryer. The electric motor for driving the drum has a variable speed. An electronic control module and the electric motor have a common housing.

[0004] DE 10 2005 041 145 A1 discloses a tumble dryer with a heat pump system. The refrigerant circuit of said heat pump system includes a compressor with a variable power output. The variable power output of the compressor allows an efficient use of energy.

[0005] EP 1 650 343 A1 discloses a tumble dryer with a heat pump system. The compressor is arranged within the air stream circuit, so that the heat released by the compressor contributes to the heating of the air stream, in particular during the heating-up phase. An additional electric heater is also arranged within the air stream circuit, which can be activated during the heating-up phase.

[0006] DE 31 13 417 A1 discloses a tumble dryer with a heat pump system. An additional electric heater is arranged within the air stream circuit in order to improve the heating-up phase.

[0007] EP 1 884 586 A2 discloses a tumble dryer with a heat pump system including a supplementary condenser. The supplementary condenser is located outside of the air stream circuit. The supplementary condenser is arranged between the proper condenser and the expansion valve. At this position the temperature is very high, so that the efficiency of the supplementary condenser is improved. By the supplementary condenser the temperature gradient between the evaporator and condenser increases, so that more moisture can be removed from the air stream.

[0008] However, the above tumble dryers have still the problem that in the beginning of the drying cycle the air cannot be heated enough in order to remove the moisture from the laundry.

[0009] It is an object of the present invention to provide a tumble dryer with a heat pump system, which allows an improved heating of the air stream.

[0010] The object of the present invention is achieved by the tumble dryer according to claim 1.

[0011] According to the present invention at least one electric and/or electronic control circuit for controlling the electric motor is at least partially arranged within the air stream circuit. Alternative wordings for "control circuit" are control unit and control module. For example the control circuit is an inverter circuit or inverter unit or inverter module adapted to control/adjust the speed of an electric motor.

[0012] The main idea of the present invention is the use of the heat generated by electric and/or electronic power circuits. Said electric and/or electronic power circuits may be provided for controlling the electric motor of the drum, the fan and/or the compressor, for example. Normally the heat of the electric and/or electronic control circuits is wasted. The heating-up phase of the drying cycle is shortened, so that the complete drying cycle can be shortened. It is possible to maximize the heat needed during the stabilized part of the drying cycle. The overall energy consumption and the overall drying time are reduced.

[0013] According to a preferred embodiment of the present invention the first heat exchanger is formed as a condenser and the second heat exchanger is formed as an evaporator. Preferably, the refrigerant circuit includes at least one expansion valve. The expansion valve allows cooling down the refrigerant between the condenser and the evaporator.

[0014] For example, at least one of the control circuits is at least partially arranged downstream of the second heat exchanger and upstream of the first heat exchanger.

[0015] Alternatively or additionally, at least one of the control circuits is at least partially arranged downstream of the first heat exchanger.

[0016] According to the preferred embodiment of the present invention at least one of the control circuits includes at least one cooling member (for example a heat sink) arranged at least partially within the air stream circuit. Preferably, at least the cooling member of the control circuit is arranged within the air stream circuit, other parts of the control circuit might be arranged outside the air stream circuit. The cooling member is part of the control circuit. Thus, even if only the cooling member of the control circuit is (at least partially) arranged within the air stream circuit, the control circuit is partially arranged within the air stream circuit.

[0017] Preferably, the cooling member comprises a number of cooling ribs formed as sheets and arranged within the air stream circuit. In particular, at least a part of the sheets are aligned parallel to the air stream.

[0018] Further, the cooling member or at least a part of the cooling member may be formed as a removable plug-in unit. In this case, the cooling member may be inserted through an appropriate aperture of the air stream circuit. The cooling member may be easily fixed by a snap-in mechanism. The aperture may be provided by a cover, which closes a part of the air stream circuit. Sealing means are provided between the aperture and the cooling member. Thus, the cooling member and the aperture form an airtight detachable connection.

[0019] Further, the speed and/or the power of the compressor may be variable. Thus, power of the compressor can be optimized in order to obtain efficient drying process.

[0020] At last, the compressor may be arranged within the air stream circuit. The heat released by the compressor can be used for the drying process and contributes to the heating of the air stream. In particular, this is advantageous during the heating-up phase of the drying cycle.

[0021] The novel and inventive features believed to be the characteristic of the present invention are set forth in the appended claims.

[0022] The invention will be described in further detail with reference to the drawings, in which

FIG 1

illustrates a schematic diagram of a tumble dryer with a heat pump system according to a preferred embodiment of the present invention,

FIG 2 and FIG 3

illustrate a schematic perspective view of the heat pump system for the tumble dryer according to the preferred embodiment of the present invention, in FIG 2 the air stream is opened and in FIG 3 the air stream is closed, and

FIG 4

illustrates the electric/electronic control circuit which is part of the heat pump system shown in FIG 2 and FIG 3.

[0023] FIG 1 illustrates a schematic diagram of a tumble dryer with a heat pump system according to a preferred embodiment of the present invention. FIG 1 shows only the substantial components of the tumble dryer with the heat pump system.

[0024] The tumble dryer with the heat pump system comprises an air stream circuit 10, a drum 12, a refrigerant circuit 14, a compressor 16, a first heat exchanger 18, a second heat exchanger 20 and an electric and/or electronic control circuit 22, a fan 24 and an expander valve 26. The control circuit 22 can also be described as control unit 22 or control module 22.

[0025] The air stream circuit 10 forms a closed loop. The drum 12 is an integrated part of the air stream circuit 10. The drum 12 is provided for receiving laundry. The fan 24 is also integrated within the air stream circuit 10 and driven by an electric motor. The fan 24 is provided for generating the air stream within the air stream circuit 10. In FIG 1 the air stream circulates counter-clockwise within the air stream circuit 10.

[0026] The refrigerant circuit 14 forms also a closed loop. The compressor 16 and the expander valve 26 are integrated parts of the refrigerant circuit 14.

[0027] The air stream circuit 10 and the refrigerant circuit 14 are thermally coupled by the first heat exchanger 18 and the second heat exchanger 20. The first heat exchanger works as a condenser 18. The second heat exchanger works as an evaporator 20.

[0028] The control circuit 22 is provided for controlling the electric motor(s) of the drum 12, the compressor 16 and/or the fan 24 (for example it is an inverter circuit adapted to control/adjust the speed of an electric motor). The control circuit 22 is arranged within the air stream circuit 10. In this example, the control circuit 22 is arranged between the evaporator 20 and the condenser 18. Alternatively or additionally, the control circuit 22 may be arranged downstream of the condenser 18 (not illustrated in the figures) with reference to the air stream circulation.

[0029] For example, the control circuit 22 for the electric motor of the compressor 16 may be arranged between the evaporator 20 and the condenser 18, and the control circuit 22 for the electric motor of the fan 24 may be arranged downstream of the condenser 18.

[0030] A refrigerant flows in the refrigerant circuit 14. In FIG 1 the refrigerant flows counter-clockwise in the refrigerant circuit 14. The refrigerant is compressed and heated by the compressor 16. The heated refrigerant reaches the condenser 18. In the condenser 18 the air stream is heated and the refrigerant is cooled down.

[0031] Between the condenser 18 and the evaporator 20 the refrigerant is expanded and additionally cooled down by the expansion valve 26. In the evaporator 20 the air stream is cooled down and dehydrated and the refrigerant is warmed up. By passing the control circuit 22 within the air stream circuit 10 the air stream is heated up again.

[0032] FIG 2 and FIG 3 illustrate a schematic perspective view of the heat pump system for the tumble dryer according to the preferred embodiment of the present invention. FIG 2 shows a base plate 30 of a tumble dryer with the substantial components of the heat pump system.

[0033] A refrigerant circuit 14, a compressor 16, a condenser 18, an evaporator 20, a control circuit 22 comprising a cooling member 23 and a circuit board 23 with electric and/or electronic components 34 (also see FIG 4), an expansion valve 26 and a motor bracket 28 are arranged on a base plate 30. The motor bracket 28 is provided for supporting an electric motor for driving the drum 12. Again, the control circuit 22 can also be described as control unit 22 or control module 22.

[0034] In FIG 2 the air stream is opened, in FIG 3 it is closed with a cover. It can be seen that the cooling member 23 of the control circuit 22 is arranged within the air stream circuit. Other parts of the control circuit 22, for example the circuit board 32 with its electric and/or electronic components 34, are arranged outside the air stream circuit. The control circuit 22 can be seen in more detail in FIG 4.

[0035] The evaporator 20, the cooling member 23 of the control circuit 22 and the condenser 18 are arranged in series. This constellation allows a small aerodynamic resistance of the air stream. In FIG 2 and FIG 3 the air stream is blown from left to right above the base plate 30. In this example, the control circuit 22 between the evaporator 20 and the condenser 18 may be provided for the electric motor of the compressor 16. In a similar way, the control circuit might be arranged downstream of the condenser 18 and may be provided for the electric motor of the drum 12 (not illustrated in the figures).

[0036] Either the complete control circuit 22 (not illustrated in the figures) or only a cooling member 23 of the control circuit 22 can be arranged within the air stream circuit 10. The cross-section of the cooling member 23 can be adapted to the cross-section of the channel for the air stream circuit 10. In particular, the cooling member 23 comprises a number of cooling ribs formed as sheets and arranged within the air stream circuit. Preferably, at least a part of the sheets are aligned parallel to the air stream.

[0037] In general, each control circuit of the tumble dryer, which is a power control circuit, can be arranged within the air stream circuit in the sense of the present invention. The power control circuits generate heat, which is normally wasted. Within the air stream circuit said heat can be used to warm up the air stream. The control circuit in the air stream circuit contributes to low energy consumption.

[0038] Although an illustrative embodiment of the present invention has been described herein with reference to the accompanying drawings, it is to be understood that the present invention is not limited to those precise embodiments, and that various other changes and modifications may be affected therein by one skilled in the art without departing from the scope or spirit of the invention. All such changes and modifications are intended to be included within the scope of the invention as defined by the appended claims.

List of reference numerals

[0039] 

10

air stream circuit

12

drum

14

refrigerant circuit

16

compressor

18

first heat exchanger, condenser

20

second heat exchanger, evaporator

22

control circuit

23

cooling member of the control circuit 22

24

fan

26

expansion valve

28

motor bracket

30

base plate

32

circuit board of the control circuit 22

34

electric and/or electronic components

Claims

1. A tumble dryer with at least one heat pump system, which tumble dryer comprises:

- an air stream circuit (10) including at least one drum (12) for receiving laundry to be dried and at least one fan (24) for generating an air stream,

- at least one refrigerant circuit (14) including at least one compressor (16),

- a first heat exchanger (18) for a thermal coupling between the air stream circuit (10) and the refrigerant circuit (14),

- a second heat exchanger (20) for a further thermal coupling between the air stream circuit (10) and the refrigerant circuit (14), and

- at least one electric motor for driving the drum (12), the compressor (16) and/or the fan (24), characterized in, that

at least one electric and/or electronic control circuit (22) for controlling the electric motor is at least partially arranged within the air stream circuit (10).

2. The tumble dryer according to claim 1,
characterized in, that
the first heat exchanger is formed as a condenser (18).

3. The tumble dryer according to claim 1 or 2,
characterized in, that
the second heat exchanger is formed as an evaporator (20).

4. The tumble dryer according to any one of the preceding claims,
characterized in, that
the refrigerant circuit (14) includes at least one expansion valve (26).

5. The tumble dryer according to any one of the preceding claims,
characterized in, that
at least one of the control circuits (22) is at least partially arranged downstream of the second heat exchanger (20) and upstream of the first heat exchanger (18) .

6. The tumble dryer according to any one of the preceding claims,
characterized in, that
at least one of the control circuits (22) is at least partially arranged downstream of the first heat exchanger (18).

7. The tumble dryer according to any one of the preceding claims,
characterized in, that
at least one of the control circuits (22) includes at least one cooling member (23) arranged at least partially within the air stream circuit (10).

8. The tumble dryer according to claim 7,
characterized in, that
the cooling member (23) comprises a number of cooling ribs formed as sheets and arranged within the air stream circuit (10).

9. The tumble dryer according to claim 8,
characterized in, that
at least a part of the sheets are aligned parallel to the air stream.

10. The tumble dryer according to any one of the claims 7 to 9,
characterized in, that
the cooling member (23) or at least a part of the cooling member (23) is formed as a removable plug-in unit.

11. The tumble dryer according to any one of the preceding claims,
characterized in, that
the speed and/or the power of the compressor (16) is variable.

12. The tumble dryer according to any one of the preceding claims,
characterized in, that
the compressor (16) is arranged within the air stream circuit (10).

Drawing