HEAT PUMP LAUNDRY DRYER

[0001] The present invention relates to a heat pump laundry dryer.

[0002] In laundry dryers, the heat pump used for drying the laundry is composed of flow ducts wherein the refrigerant flows, a compressor that provides circulation by pressurizing the refrigerant, an evaporator and a condenser, and the drying process is performed by passing the processing air over the laundry. The condenser disposed in the heat pump functions as the heater and the evaporator functions as the condenser. The processing air is heated while passing from the condenser, delivered over the laundry as being heated and after dehumidifying the laundry, leaves its moisture while passing over the evaporator. In the cycle wherein the refrigerant circulates in the flow ducts, the refrigerant that is delivered from the compressor to the condenser with increased pressure and temperature enters the condenser by passing through the capillary tube and absorbs heat in order to receive moisture from the processing air in the evaporator. During the drying air cycle, the temperature of the processing air coming over the evaporator increases as the laundry in the drum is heated and respectively the working temperatures of the elements in the refrigerant cycle, that is the compressor, the evaporator and the condenser also increase continuously. The increase of temperature in the processing air affects the refrigerant circulating in the cycle of the heat pump and when not intervened, the evaporator is filled with the refrigerant in vapor phase having poor heat transfer capability, the overheating problem arises and the dehumidifying capacity of the overheated evaporator decreases. In the heat pump, the temperature of the refrigerant reaches around 45 - 50 degrees at the compressor inlet as a result of overheating in the refrigerant line and the temperature at the compressor outlet becomes above the inlet temperature. The refrigerant leaving the compressor with high temperature causes both the condensing temperature and the evaporating temperature to increase. Overheating of the refrigerant causes the compressor to operate within an inefficient temperature range and energy consumption increases as a result of this. [0003] In the state of the art German Patent No. DE4409607, in a dryer with a heat pump, embodiments are explained that relate to the prevention of overheating problem which occurs during the refrigerant cycle.

[0004] The aim of the present invention is the realization of a heat pump laundry dryer that is prevented from overheating.

[0005] The heat pump laundry dryer realized in order to attain the aim of the

present invention has a refrigerant line composed of flow ducts wherein the refrigerant flows, a heat exchanger is disposed at the portion of the refrigerant line between the evaporator and the compressor and the refrigerant is provided to be cooled before entering the compressor.

[0006] In an embodiment of the present invention, the laundry dryer comprises a temperature sensor that detects the temperature in the refrigerant line between the evaporator and the compressor and a control unit which detects whether or not there is overheating in the heat pump by evaluating the data received from the temperature sensor. In this embodiment, furthermore a three-way valve is disposed in the refrigerant line prior to the heat exchanger and a by-pass line is provided between the valve and the compressor.

[0007] The control unit provides the valve to direct the refrigerant to the

compressor through the by-pass line at the beginning of the drying process when overheating of the heat pump has not yet started.

[0008] The control unit provides the valve to direct the refrigerant to the

compressor through the heat exchanger if the control unit detects that overheating in the heat pump has started in accordance with the temperature data received from the temperature sensor.

[0009] In an embodiment of the present invention, a cooling fan is used in the heat pump laundry dryer for cooling the compressor and the heat exchanger is disposed between the cooling fan and the compressor to remain on the refrigerant line.

[0010] In another embodiment of the present invention, a condensation tray is used in the heat pump laundry dryer wherein the water condensed in the evaporator is collected and the water collected in the condensation tray is discharged by a pump by being passed through the heat exchanger, the cooling effectiveness of the heat exchanger is increased.

[001 1] In the heat pump laundry dryer, the problem of overheating is prevented by means of disposing the heat exchanger at the compressor inlet portion of the refrigerant line and the efficiency of the compressor is increased.

[0012] The laundry dryer realized in order to attain the aim of the present

invention is illustrated in the attached figures, where:

[0013] Figure 1 - is the schematic view of a heat pump laundry dryer wherein a heat exchanger is provided on the refrigerant line.

[0014] Figure 2 - is the schematic view of a heat pump laundry dryer in another embodiment of the present invention.

[0015] Figure 3 - is the schematic view of a heat pump laundry dryer comprising the compressor cooling fan.

[0016] Figure 4 - is the schematic view of a heat pump laundry dryer comprising the evaporator condensation tray.

[0017] The elements illustrated in the figures are numbered as follows:

1. Laundry dryer

2. Drum

3. Processing air fan

4. Air circulating duct

5. Heat pump

6. Compressor

7. Evaporator

8. Condenser

9. Capillary tube

10. Refrigerant line

1 1. Heat exchanger

12. Cooling fan

13. Temperature sensor

14. Control unit

15. Valve

16. By-pass line

17. Condensation tray

18. Condensing water line 19. Pump

[0018] The laundry dryer (1) comprises a drum (2) wherein the laundry to be dried is placed, an air circulating duct (4) wherein the processing air cycle is performed by a processing air fan (3) and a heat pump (5) wherein the refrigerant cycle is performed.

[0019] The heat pump (5) comprises a compressor (6) that provides aspiration and compressing of the refrigerant, an evaporator (7) providing the processing air in the air circulating duct (4) to be dehumidified, a condenser (8) providing the dehumidified processing air to be heated, a capillary tube (9) disposed between the condenser (8) and the evaporator (7) and a refrigerant line (10) that provides the refrigerant compressed by the compressor (6) to be delivered to the compressor (6) after flowing through the condenser (8), the capillary tube (9) and the evaporator (7) in that order.

[0020] The laundry dryer (1) of the present invention comprises a heat exchanger (1 1 ) disposed at the portion of the refrigerant line (10) between the evaporator (7) and the compressor (6) and which provides the refrigerant to be cooled before entering the compressor (6) (Figure 2, Figure 3, Figure 4, Figure 5).

[0021] The heat exchanger (1 1 ) decreases the temperature of the refrigerant entering to the compressor (6) in the portion of the refrigerant line (10) between the evaporator (7) and the compressor (6). Decreasing the temperature of the refrigerant entering to the compressor (6) provides in enchainment to also decrease the compressor (6) exit temperature, the condenser (8) temperature and the evaporator (7) temperature.

Consequently, the problem of overheating in the heat pump (5) is prevented and also the compressor (6) is provided to operate within a temperature range that improves efficiency. The heat exchanger (1 1 ) prevents overheating of the heat pump (5) by cooling the refrigerant in the stage when the refrigerant passes through the compressor (6), in other words at the beginning of the refrigerant cycle.

[0022] In an embodiment of the present invention, the laundry dryer (1 ) comprises a temperature sensor (13) that detects the temperature in the refrigerant line (10) between the evaporator (7) and the compressor (6), a control unit

(14) that detects whether or not there is overheating in the heat pump (5) by evaluating the data received from the temperature sensor (13), a valve

(15) disposed prior to the heat exchanger (1 1) in the refrigerant line (10) between the evaporator (7) and the compressor (6) and which directs the refrigerant and a by-pass line (16) located between the valve (15) and the compressor (6) inlet which provides the refrigerant received from the evaporator (7) to be delivered to the compressor (6) (Figure 3).

[0023] In this embodiment, the control unit (14) provides the valve (15) to direct the refrigerant directly to the compressor (6) through the by-pass line (16) at the beginning of the drying process when the heat pump (5) is not overheated.

[0024] The control unit (14) provides the valve (15) to direct the refrigerant to the compressor (6) through the heat exchanger (1 1 ) if the control unit (14) detects overheating in the heat pump (5) in accordance with the

temperature data received from the temperature sensor (13).

[0025] In an embodiment of the present invention, the laundry dryer (1 ) comprises a cooling fan (12) that provides cooling of the compressor (6), the refrigerant line (10) between the evaporator (7) and the compressor (6) is arranged so as to pass between the cooling fan (12) and the compressor (6) and the heat exchanger (1 1 ) is disposed at the portion of the refrigerant line (10) extending between the cooling fan (12) and the compressor (6) (Figure 4). The cooling fan (12) increases the cooling effect of the heat exchanger (1 1 ).

[0026] In another embodiment of the present invention, the laundry dryer (1)

comprises a condensation tray (17) wherein the water condensed in the evaporator (7) collects, the tube shaped heat exchanger (1 1) disposed on the refrigerant line (10) between the evaporator (7) and the compressor (6) and a condensing water line (18) having a pump (19) that provides the water in the condensation tray (17) to be discharged by being passed through the heat exchanger (1 1 ) (Figure 5). In this embodiment, the cooling effect of the heat exchanger (1 1 ) is increased by using the water collected in the condensation tray (17). [0027] In this embodiment, the control unit (14) provides the water in the condensation tray (17) to be discharged by being passed through the condensing water line (18) and the heat exchanger (1 1 ) by operating the pump (19) if the control unit (14) detects overheating in the heat pump (5) according to the data received from the temperature sensor (13).

[0028] In the laundry dryer (1 ) of the present invention, the problem of

overheating in the heat pump (5) is prevented and the efficiency of the compressor (6) is increased by means of disposing the heat exchanger (1 1 ) at the portion of the refrigerant line (10) of the compressor (6) inlet.

[0029] It is to be understood that the present invention is not limited by the

embodiments disclosed above and a person skilled in the art can easily introduce different embodiments. These should be considered within the scope of the protection postulated by the claims of the present invention.