Laundry drying device having a heat pump

[0001] The invention relates to a laundry drying device having a heat pump.

[0002] Fully automatic washer-dryers are known, which are provided with a compression heat pump so as to reduce the energy consumption during the drying process. The configuration comprising water condensation and resistance heating which is traditionally used in fully automatic washer-dryers is essentially replaced here by a closed refrigerant circuit filled with refrigerant comprising a compressor, evaporator, condenser and governor. On account of the restricted available space, only very specific arrangements are possible for the closed refrigerant circuit, without changing the overall device dimensions.

[0003] An arrangement of a compact unit for the refrigerant circuit on a base plate, which closes off the housing of the fully automatic washer-dryer towards the bottom, is known for a fully automatic washer-dryer VA-1000 by the Japanese company National. The following disadvantages in terms of energy result here during the drying process:

[0004] The air paths from the tub to the heat exchangers (evaporator, condenser) are very long. A precondensation of the warm and damp process air in the drying process results en route from the tub to the evaporator. This precondensation reduces the pump output within the refrigerant circuit, since less water per time unit precipitates out on the evaporator and thus less energy can also be pumped. Further losses develop from the condenser to the air inlet into the drum as a result of heat losses on the channel walls up until entry into the drum.

[0005] It is the object of the present invention to reduce an energy consumption of a laundry drying device having a heat pump without increasing its external dimensions.

[0006] The laundry drying device (in particular a fully automatic washer-dryer or a separate tumble dryer) has a rotatable laundry drum and a heat pump has at least one compressor, an evaporator, a condenser and a governor. The compressor is arranged at least partially, preferably completely, between the laundry drum and a rear wall. The condenser is also arranged at least partially, preferably completely, above the laundry drum.

[0007] This clever arrangement of the evaporator and condenser minimizes energy losses. It provides the process air with a short route from the condenser into the laundry drum. In particular, the spatial vicinity of the evaporator relative to the air outlet out of the drum (air intake opening) produces an improved condensation in the evaporator, which is desirable since a condensation in other regions (e.g. the drum) produces a loss of pump output. Only the phase changeover in the evaporator produces a recovery.

[0008] In the event that the laundry drum is surrounded by a drum housing, like for instance in the case of a fully automatic washer-dryer, it is preferable for the evaporator to be arranged at least partially between a drum housing and a rear wall; and for the condenser to be arranged at least partially above the drum housing.

[0009] To this end, the evaporator is preferably configured in such a way that process air passes therethrough from the bottom up. This is then particularly preferred if the evaporator is arranged above a process air intake opening in the laundry drum and is connected herewith by way of an upwardly guiding process air duct. A fully automatic washer-dryer herewith prevents water from reaching the heat exchangers (evaporator and condenser) usually provided with aluminum fins, since the arrangement of the evaporator and condenser lies above the normal water level during the washing process. Condensate in the evaporator also unavoidably proceeds downwards into the channel section (return pipe) to the process air intake opening and can thus counteract the “lint deposits” on the fins, since the condensate water carries the lint and other deposits with it downwards.

[0010] In order to shorten the path to the laundry drum and/or to the drum housing, it is also advantageous for the condenser to be arranged in a front region of the laundry drying device. This is particularly the case for laundry drying devices with a process air supply opening (or as the case may be, injection opening) into the laundry drum and/or the drum housing in the region of the seal.

[0011] It is also advantageous for a compact design for a process air fan to be arranged between the evaporator and the condenser, in particular laterally offset from the condenser.

[0012] A further improvement in the energy balance is advantageously achieved by using a laundry drum and/or a drum housing made of plastic, in particular a tub in the case of a fully automatic washer-dryer, namely by means of the thermal insulation improved as a result.

[0013] Another further improvement in the energy balance is advantageously achieved by means of providing an insulation (e.g. a layer made of insulating material) of the laundry drum and/or the drum housing, in particular tub, e.g. from the outside.

[0014] The above invention can be used particularly advantageously if the laundry drying device is a fully automatic washer-dryer, with the drum housing then corresponding to a tub.

[0020] FIG. 4 shows a schematic illustration of a heat pump-equipped fully automatic washer-dryer 1 as claimed in the prior art, in which a tub 2 having a laundry drum rotatably mounted therein (no FIG.) is connected to a process air duct 3 indicated by the dashed arrows. The process air is moved by means of a fan 4 coupled in the process air duct 3. The process air taken in from the tub 2 during the drying process is dried and heated by means of a heat pump 5 and is then blown back into the tub 2. The effectiveness of a heat pump 5 in a fully automatic washer-dryer 1 is basically known. The heat pump 5 typically comprises an evaporator 6, a condenser 7, a compressor 8 with a cooling fan and a governor 9, which are contained in a closed circuit filled with refrigerant, and is indicated here by the continuous arrows. While the damp process air is cooled in the evaporator 6 and the vapor contained therein is at least partially condensed out, the dry air in the condenser 7 is heated again and blown back into the tub 2. In the embodiment shown, as is known by the Japanese company National, the heat pump 5, as indicated, is arranged as a compact unit for the refrigerant circuit on the base plate 10 of the fully automatic washer-dryer 1. The energy disadvantages already discussed above result here.

[0021] FIG. 1 shows an inventive heat pump-equipped fully automatic washer-dryer 11, in which the evaporator 6 is now arranged between the drum housing 2 and a rear wall 12 and the condenser 7 is arranged above the drum housing 2. Only the compressor 8 is still arranged in the region of the base plate 10. The evaporator 6 is configured and arranged so that process air passes therethrough from the bottom up. In particular, the evaporator 6 is arranged above a process air intake opening 13 of the tub 2 and is connected hereto by way of an at least partially upwardly guiding section 14 of the process air duct 3. The condenser 7 is now arranged in a front region of the laundry drying device 11 and the process air fan 4 is arranged between the evaporator 6 and the condenser 7.

[0022] FIG. 2 shows the inventive heat pump-equipped fully automatic washer-dryer 11 in a side view with the evaporator 6 arranged to the rear of the drum housing. A process air duct section 14 proceeds downwards only briefly from the process air intake opening 13 and then upwards into the evaporator, and from there further upwards to the fan 4. The process air is blown forwards by the fan 4 to the condenser 7 and from there briefly to an air injection opening on the upper edge of a seal 15 into the drum housing 2.

[0023] FIG. 3 shows a top view of the position of the process air fan 4, which blows process air into the condenser 7 arranged in a front part via the channel 3. The process air fan 4 is arranged laterally offset from the condenser.

[0024] The present invention is naturally not restricted to the described exemplary embodiments. A separate tumble dryer can naturally also be used as a drying device, the laundry drum can be rotatable in the device without any additional housing.

• [0025] 1 Heat pump-equipped fully automatic dryer
• [0026] 2 Tub
• [0027] 3 Process air duct
• [0028] 4 Process air fan
• [0029] 5 Heat pump
• [0030] 6 Evaporator
• [0031] 7 Condenser
• [0032] 8 Compressor
• [0033] 9 Governor
• [0034] 10 Base plate
• [0035] 11 Heat pump-equipped fully automatic washer-dryer
• [0036] 12 Rear wall
• [0037] 13 Process air intake opening
• [0038] 14 Process air duct section
• [0039] 15 Seal