The present invention relates to a laundry dryer with a heat pump system according to the preamble of claim 1.

The heat pump technology in a laundry dryer is at present the most efficient way to dry clothes in terms of energy consumption. In a heat pump system of the laundry dryer an air stream flows in a closed air stream circuit. Further, the heat pump system includes a closed refrigerant circuit. The air stream is moved by a fan, passes through a laundry chamber, which is preferably formed as a rotatable laundry drum, and removes there water from wet clothes. Then, the air stream is cooled down and dehumidified in an evaporator, heated up in a condenser and re-inserted into the laundry drum again. The refrigerant is compressed by a compressor, condensed in the condenser, laminated in an expansion device and then vaporized in the evaporator. Thus, the condenser and the evaporator are components of the air stream circuit as well as the refrigerant circuit. The condenser and the evaporator are heat exchangers between the air stream circuit and the refrigerant circuit.

Usually, the components of the heat pump system are placed in a basement of the laundry dryer. In particular, the compressor, the evaporator and the condenser are arranged in said basement below the laundry drum. Thus an air duct of the air stream circuit has to pass the basement.

FIG 6 illustrates a top view of the open basement of the laundry dryer according to the prior art. The compressor 14, the evaporator 16, the condenser 18, the fan 20 and the motor 22 are arranged in the lower casing 10 of the basement. The evaporator 16 and the condenser 18 are placed in a straight air duct. The evaporator 16 and the condenser 18 are arranged in parallel. The straight air duct causes that the air stream has to pass an angle at the inlet and at the outlet of said straight air duct. Such angles in the air stream circuit cause pressure drops and turbulences increasing the energy consumption and the noise.

German patent application DE 42 12 700 A1 discloses a laundry dryer having a heat pump circuit.

International patent application WO 2008/077838 A1 discloses a washer/dryer that is more efficient and operates with less noise.

German patent application DE 10 2006 016294 A1 discloses a domestic appliance for care of items of laundry.

Japanese patent application JP 2007 000386 A discloses a clothes dryer.

It is an object of the present invention to provide a laundry dryer with a heat pump system, wherein the flow of the air stream is improved.

The object of the present invention is achieved by the laundry dryer according to claim 1.

According to the present invention the air duct comprises at least one curved portion, wherein the evaporator and the condenser are arranged inside said curved portion of the air duct.

The core of the present invention is the combination of the curved portion of the air duct in the basement of the laundry dryer on the one hand and the arrangement of the evaporator and the condenser inside said curved portion of the air duct on the other hand. The curved portion prevents corners inside the air duct, so that pressure drops in the air duct are reduced. The air flow through the evaporator and condenser is optimized. The heat exchange between the refrigerant circuit and the air stream circuit increases. The dimensions of the evaporator and condenser may be reduced. This allows a redistribution of the components in the basement of the laundry dryer. The energy consumption of the motors for the compressor and the fan is reduced. Further, the noise of the laundry dryer is reduced.

At least a part of the curved portion of the air duct has the structure of an arc of a circle.

Further, the evaporator and the condenser are inclined to each other. The orientations of the evaporator and condenser are adapted to the structure of the air duct.

For example, the continuations of the main planes of the evaporator and the condenser intersect in the centre of the circle defining the arc of the air duct.

Additionally or alternatively, the main planes of the evaporator and condenser may be arranged perpendicular to the direction of the air duct.

In particular, the fan of the air stream circuit is arranged at the end of the air duct or at the end of the curved portion of said air duct in the basement.

For example, the air duct or the curved portion of said air duct extends horizontally in the basement. In this case, the bending of the air duct extends in a horizontal plane.

Preferably, the one or more curved portions of the air duct extend substantially over the whole air duct in the basement.

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

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

FIG 1

shows an upper perspective exploded view of a basement of a laundry dryer according to a preferred embodiment of the present invention,

FIG 2

shows a lower perspective exploded view of the basement of the laundry dryer according to the preferred embodiment of the present invention,

FIG 3

shows a perspective view of the open basement of the laundry dryer according to the preferred embodiment of the present invention,

FIG 4

shows a top view of the open basement of the laundry dryer according to the preferred embodiment of the present invention,

FIG 5

shows a perspective view of the laundry dryer according to the preferred embodiment of the present invention, and

FIG 6

shows a top view of the open basement of the laundry dryer according to the prior art.

FIG 1 illustrates an upper perspective exploded view of a basement of a laundry dryer according to a preferred embodiment of the present invention. The basement is provided for a laundry dryer with a heat pump system. The basement forms a lower portion of the laundry dryer and is arranged below a laundry drum.

The basement advantageously includes a lower casing 10 and an upper casing 12. Further, the basement includes a compressor 14, an evaporator 16, a condenser 18, a fan 20 and a motor 22. The lower casing 10 and the upper casing 12 enclose the compressor 14, the evaporator 16, the condenser 18, the fan 20 and the motor 22.

The laundry dryer comprises a closed air stream circuit. The air stream circuit includes the fan 20, the laundry drum, the evaporator 16 and the condenser 18. The heat pump system comprises a closed refrigerant circuit. The refrigerant circuit includes the compressor 14, the evaporator 16, the condenser 18 and an expansion device. The expansion device is not shown in FIG 1.

In the air stream circuit an air stream is moved by the fan 20, passes the laundry drum and removes water from wet clothes inside said laundry drum. The motor 22 is provided for driving the fan 20. Then, the air stream is cooled down and dehumidified in the evaporator 16, heated up in the condenser 18 and re-inserted into the laundry drum again. In the refrigerant circuit the refrigerant is compressed by the compressor 14, condensed in the condenser 18, laminated in the expansion device and vaporized in the evaporator 16. The evaporator 16 and the condenser 18 are heat exchangers between the air stream circuit and the refrigerant circuit.

The air stream circuit comprises an air duct 24. The air duct 24 is formed by the lower casing 10 and the upper casing 12. In FIG 1 a lower part of the air duct 24 formed by the lower casing 10 is visible. The air duct 24 has the structure of an arc of a circle. Thus, the air duct 24 has no corners and edges. The evaporator 16 and the condenser 18 are arranged in the air duct 24. The orientations of the evaporator 16 and condenser 18 are adapted to the run of the air duct 24, so that the flow directions through the evaporator 16 and condenser 18 are substantially the same as in the air duct 24. The fan 20 is arranged at the end of the air duct 24.

The structure of the curved air duct 24 and the orientations of the evaporator 16 and condenser 18 allow an improved air stream. Pressure drops and turbulences of the air stream are reduced. The noise generated by the air stream is also reduced.

FIG 2 illustrates a lower perspective exploded view of the basement of the laundry dryer according to the preferred embodiment of the present invention. The basement includes the lower casing 10 and the upper casing 12. The compressor 14, the evaporator 16, the condenser 18, the fan 20 and the motor 22 are enclosed by the lower casing 10 and the upper casing 12.

The air duct 24 is formed by the lower casing 10 and the upper casing 12. In FIG 2 an upper part of the air duct 24 formed by the upper casing 12 is visible. The air duct 24 has the structure of an arc of a circle.

FIG 3 illustrates a perspective view of the open basement of the laundry dryer according to the preferred embodiment of the present invention. The compressor 14, the evaporator 16, the condenser 18, the fan 20 and the motor 22 are arranged in the lower casing 10 and covered by the upper casing 12.

In particular, FIG 3 clarifies the orientation of the evaporator 16 and the condenser 18 inside the air duct 24. The flow directions of the air stream through the evaporator 16 and condenser 18 are adapted to the flow direction in the air duct 24.

FIG 4 illustrates a top view of the open basement of the laundry dryer according to the preferred embodiment of the present invention. The compressor 14, the evaporator 16, the condenser 18, the fan 20 and the motor 22 are arranged in the lower casing 10 of the basement.

The side walls of the air duct 24 are smooth and have no corner or edges. FIG 4 clarifies the orientations of the evaporator 16 and condenser 18, wherein the flow directions through the evaporator 16 and condenser 18 are substantially the same as the air flow direction in the air duct 24. In other words, the evaporator 16 and the condenser 18 are inclined to each other, wherein their main planes advantageously intersect in the central point of the circle defining the arc of the air duct 24. The arrows 30 represent the air stream through the air duct 24.

FIG 5 illustrates a perspective view of the laundry dryer according to the preferred embodiment of the present invention. The laundry dryer comprises the laundry drum 26 and the basement 28. The laundry drum 26 is arranged in a central portion of the laundry dryer. The basement 28 forms a lower portion of the laundry dryer. In this example, the air duct 24 extends along a horizontal direction inside the basement.

FIG 6 illustrates a top view of the open basement of the laundry dryer according to the prior art. The compressor 14, the evaporator 16, the condenser 18, the fan 20 and the motor 22 are arranged in the lower casing 10 of the basement. The evaporator 16 and the condenser 18 are placed in a straight air duct. The evaporator 16 and the condenser 18 are arranged in parallel. The straight air duct causes that the air stream has to pass an angle at the inlet band outlet of said straight air duct. Such angles in the air stream circuit cause pressure drops and turbulences increasing the energy consumption and the noise. His problems have been overcome by the present invention.

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 that precise embodiment, and that various other changes and modifications may be affected therein by one skilled in the art without departing from the scope 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.

10

lower casing

12

upper casing

14

compressor

16

evaporator

18

condenser

20

fan

22

motor

24

air duct

26

laundry drum

28

basement

30

air stream