DRYER FOR DRYING LAUNDRY AND METHOD OF OPERATING A DRYER

Abstract

 A dryer (1) for drying laundry (4) comprises a drum (3) for receiving the laundry (4), with at least one drum inlet port (17) for receiving drying air, and at least one drum outlet port (22) for discharging moist drying air, a drying unit (20) for providing the drying air for drying the laundry (4), which is air-conductively connected to the at least one drum inlet port (17) and the at least one drum outlet port (22), and a flow restriction (24) for guiding the drying air to the at least one drum inlet port (17).

Description

[0001] The invention relates to a dryer for drying laundry. The invention further relates to a method of operating a dryer.

[0002] A dryer serves to reduce the moisture of wet laundry by means of a flow of hot and dry air. There is a continuous need to enhance the robustness and efficiency of conventional dryers.

[0003] An object of the present invention is to enhance a dryer by increasing its robustness and efficiency.

[0004] This object is achieved in accordance with the invention by a dryer having the features set out in claim 1. The inventive dryer can be operated in a highly robust and energy-efficient manner. The flow restriction reduces or even avoids the flow of drying air around the drum and forces the drying air to flow through the drum where it can effectively remove moisture from the laundry.

[0005] The flow restriction can be of contact type, in particular a sealing ring, or of non-contact type. A contactless flow restriction is wear resistant. The contact type flow restriction however provides the better sealing effect.

[0006] Preferably, the flow restriction is annular shaped, particularly circular shaped, more particular aligned concentrically with the rotational axis of the drum. The flow restriction can be located at a front side and/or at a back side and/or at a cylindrical wall of the drum. Preferably, it is located at that side of the drum to which a drive shaft for rotating the drum is attached. Vibrations at the flow restriction can thereby be reduced. Usually, the drive shaft is attached at the back side of the drum. More preferably, the at least one drum outlet port and/or the at least one drum inlet port and the flow restriction are arranged at the same side of the drum, particularly at the back side and/or at the front side. By this, the drying air flow is particularly efficient and the flow restriction is less exposed to vibrations and wear.

[0007] Preferably, the labyrinth seal comprises a drum sealing element that is attached to the drum and a stationary sealing element that is attached to a tub and/or a housing and/or a mounting part, wherein the drum sealing element and the stationary sealing element act together to form the labyrinth seal. The labyrinth seal preferably comprises at least one, particularly at least two, more particular at least three, more particular at least four, more particular at least six flow deflection elements. Such flow deflection elements are also referred to as teeth. Preferably, the teeth of the drum sealing element and of the stationary sealing element overlap each other in radial direction with respect to the rotational axis. The radial distance and/or the axial distance between two adjacent teeth can be within a range of 0.5 mm to 10 mm, particularly 1 mm to 5 mm. The teeth can be arranged concentric to the rotational axis. Such a labyrinth seal allows for a sufficient sealing effect and is resistant to wear.

[0008] According to an aspect of the invention, the flow restriction, particularly the labyrinth seal, is elastically deformable. Preferably, the teeth of the labyrinth seal comprise a rubber-elastic material. Wear or damage caused by contact of adjacent teeth can thus be avoided.

[0009] The dryer comprises a drive unit for rotating the drum around a rotational axis. A drive shaft of the drive unit is connected to the drum. The drive shaft is rotatably mounted with respect to the housing.

[0010] The dryer may be a washer dryer that combines the functionalities of washing and drying laundry. In particular, these functions are achieved with only one drum. The washer dryer is configured such that it comprises the additional functionality of washing and/or spin-drying.

[0011] A tub of the washer dryer is arranged within a housing. Preferably, it is attached to the housing by means of springs and/or dampers. The washer dryer can be a front loader or a top loader. The rotational axis of the top loader may be aligned horizontally or vertically. The drum is arranged inside of the tub. The drum can be attached to the tub by means of a drive shaft. Preferably, the drive shaft is rotatably mounted to the tub. The washer dryer can comprise a drive unit for rotating the drum, particularly for providing a torque that is necessary to obtain a spinning movement. Such a spinning motion allows water to be efficiently removed from the laundry, but causes increased vibration.

[0012] According to an aspect of the invention, the drying unit is configured such that it circulates drying air through the drum. Particularly, it can be configured not to admix air from the environment. Alternatively, the drying unit can comprise a multi-port valve to admix environmental air with recirculated drying air. Environmental air can for example be used to cool down the recirculated drying air.

[0013] The drying unit can comprise a condenser for drying moist air and/or a fan for conveying the air and/or a heater for heating the air. Preferably, the fan is located downstream and/or upstream of the condenser. The heater can be located downstream of the fan. By this, an exposure of the fan to heated air can be avoided, which increases the service life of the fan. The condenser can be air-cooled and/or water-cooled and/or be of electric type. The heater can be an electric heater.

[0014] According to an aspect of the invention, the dryer comprises a control unit for controlling the drying unit and/or a sealing air supply and/or the drive unit. The control unit can be in signal connection with these components. Preferably, it is configured such that it can reversibly activate the drying unit and/or the sealing air supply and/or the drive unit. The process of drying is preferably automated by means of the control unit. Particularly, the control unit can be configured such that it activates the sealing air supply depending on the activation of the drying unit, so that sealing and drying air are available simultaneously.

[0015] The drum can comprise two face sides, a front side and a back side, and a cylindrical wall. The at least one drum inlet port and/or the at least one drum outlet port can be arranged at the front side and/or the back side and/or the cylindrical wall of the drum.

[0016] According to an aspect of the invention, the at least one drum inlet port can comprise multiple inlet openings. The multiple inlet openings can be arranged in a circular pattern around a rotational axis of the drum. Preferably, the multiple inlet openings are uniformly distributed in the circumferential direction and/or the axial direction with regard to the rotational axis of the drum and/or distributed in a non-uniform pattern that allows an enhanced, particularly more uniform, flow distribution within the drum. For example, an area density of the inlet openings can increase and/or decrease with the distance of the respective inlet opening from the at least one drum outlet port.

[0017] The drum can comprise multiple drum inlet ports. Each drum inlet port may have multiple inlet openings, like perforations, particularly at a face side and/or a cylindrical wall of the drum. Such perforations can be distributed uniformly or non-uniformly such that a uniform flow distribution is achieved within the drum. For example, the area density of the perforations can increase with an increased and/or decreased distance from the drum outlet port.

[0018] A dryer as claimed in claim 2 is particularly robust and energy-efficient. The sealing air provided by the sealing air supply further increases the robustness and energy-efficiency of the dryer. The sealing air supply provides for a contactless sealing, particularly for at least partial suppression of a drying air flow bypassing the drum. Such a non-contact seal is not subject to wear. The combination of both the flow restriction and the sealing air supply results in the synergetic effect that the sealing air can be used particularly efficient at a reduced flow cross section that is obtained by the flow restriction. Since the drying air flow around the drum is at least substantially decreased, energy used for heating the drying air can be saved. The energy consumption of the dryer is further reduced due to the decreased mass flow of moist drying air that has to be cooled down within a condenser of the drying unit. The dryer can thus be operated particularly robust and energy-efficient. With the sealing air supply, a non-contact sealing of a gap between the drum and a tub and/or a housing can be achieved such that vibrations due to an unbalanced distribution of the laundry within the drum does not lead to wear. The dryer is thus robust and energy-efficient. The sealing air supply comprises at least one sealing air duct for conducting the sealing air to the at least one sealing air inlet port. The sealing air duct can be configured such that it connects the at least one sealing air inlet port to the environment and/or to the drying unit, in particular to a drying air duct. Preferably, the fan of the drying unit is arranged such that it conveys both, the drying air and the sealing air. Therefore, the sealing air duct can connect the at least one sealing air inlet port with an outlet of the fan of the drying unit. The sealing air supply can comprise a separate fan for conveying the sealing air to the at least one sealing air inlet port. Preferably, the sealing air duct is configured such that non-heated air is provided at the at least one sealing air inlet port.

[0019] The sealing air supply can comprise at least one valve, in particular an adjustable valve with an adjustable flow area, more particular an electrically adjustable valve. The control unit can be configured to control the at least one valve. By this, the control unit can control the sealing air flow whereby the efficiency of the dryer can be increased. Particularly, the control unit can ensure that the necessary mass flow for the intended sealing effect is provided. A similar effect is achieved if the control unit is configured to control the fan speed.

[0020] A dryer as claimed in claim 3 is particularly energy-efficient. Locating the flow restriction at a face side of the drum enables to guide the inflow of drying air into the drum and/or to the laundry. By this, a particularly uniform and efficient flow distribution within the drum can be obtained. Preferably, the flow restriction is located at a face side at which the drum is rotatable mounted, particularly at the back side, to avoid wear.

[0021] A dryer as claimed in claim 4 can be operated particularly energy-efficient. The arrangement of the at least one drum outlet port for discharging the drying air from the drum at a face side of the drum ensures a particularly uniform flow distribution within the drum and thus an efficient drying process. Preferably, the at least one drum outlet port is located opposite to the at least one drum inlet port. Preferably, the at least one drum inlet port and the at least one drum outlet port are located at different sides of a horizontal plane which includes the rotational axis.

[0022] A dryer as claimed in claim 5 can be operated particularly energy-efficient. The sealing air supply can comprise multiple sealing air inlet ports. The arrangement of the at least one sealing air inlet port at the flow restriction allows to provide sealing air in an easy and efficient manner. Preferably, the at least one sealing air inlet port opens into a distribution chamber which distributes the sealing air to at least one sealing air outlet opening. Preferably, the at least one sealing air outlet opening has a circular shape and/or is arranged in a circular manner.

[0023] A dryer as claimed in claim 6 can be operated particularly energy-efficient. Preferably, the at least one sealing air outlet opening comprises at least one nozzle. The nozzle can be configured such that it directs the sealing air flow contrary to the direction of the drying air flow. The resulting back pressure allows for an enhanced sealing effect. Preferably, such a nozzle is configured such that the sealing air flow is directed against the drying air flow and/or to the flow restriction, particularly when the nozzle is located downstream of the flow restriction. The sealing air can thus choke or seal the flow restriction. By this, a drying air flow over the flow restriction can completely be avoided. Preferably, each of the sealing air outlet openings comprises a nozzle for specifying the direction of the sealing air flow. The nozzles can be flat jet nozzles and/or round jet nozzles. Preferably, the sealing air outlet openings are uniformly distributed, in particular around the rotational axis and/or along the flow restriction. Alternatively, the sealing air outlet openings can be arranged in a non-uniform pattern, preferably such that a uniform distribution of the sealing air flow is obtained, particularly at the flow restriction. The at least one sealing air outlet opening can have a circular shape. Preferably, the at least one sealing air outlet opening is in connection with a distribution chamber. Preferably, the distribution chamber has a circular shape.

[0024] A dryer as claimed in claim 7 is particularly economical to produce and energy efficient to operate. As the sealing air duct connects the sealing air inlet port with the drying air duct between the condenser and the heater, non-heated dry air can be provided as sealing air. Preferably, the sealing air duct is connected to an outlet of the drying air fan. The sealing air duct thus bypasses the heater, whereby heating energy can be saved.

[0025] The dryer as claimed in claim 8 can be operated particularly energy-efficient. Preferably, the drum sealing element and the stationary sealing element act together to form the flow restriction. The drum sealing element can be a seal and the stationary sealing element can be a sealing surface or vice versa. The flow restriction can thus be configured particularly effective. The stationary sealing element can be attached to a tub and/or a housing and/or a mounting part.

[0026] The dryer as claimed in claim 9 is particularly energy-efficient and robust. The features of claim 9 refer to an independent invention, which nevertheless can be combined with the aforementioned aspects. Particularly, the invention relates to a dryer with a drum, a drying unit, a flow restriction and a retracting mechanism according to claim 9 with or without a sealing air supply. The retracting mechanism can comprise a retracting drive for retracting the drum sealing element and/or the stationary sealing element. The retracting drive can be connected to the control unit. In the retracted position, the retracting mechanism and the flow restriction are arranged in an open state. In a restriction position, the retracting mechanism and the flow restriction are arranged in a closed state. Such retracting mechanism ensures that the flow restriction is not exposed to vibrations, particularly during a spinning phase of the washing or drying process. The retracting mechanism is preferably configured such that it retracts the respective sealing element by a distance of at least 1 mm, particularly at least 2 mm, particularly at least 5 mm, particularly at least 10 mm.

[0027] According to a further aspect of the invention, the flow restriction and/or the retracting mechanism are slotted in radial direction. The flow restriction and the retracting mechanism may be divided into multiple sections. Circumferential stresses due to the retraction movement can thus be avoided. Preferably, a gap between adjacent sections is available in the open state and closed in the restriction position.

[0028] A dryer as claimed in claim 10 is particularly robust. The at least one bias spring can be a coil spring. The bias spring is preferably arranged concentric to the rotational axis of the drum. Preferably, the bias spring surrounds the rotational axis. The bias spring can be configured such that it acts on the retracting mechanism in radial direction with respect to the rotational axis. The bias spring can be a metal spring. The bias spring can comprise a rubber-elastic material. Preferably, the bias spring is formed by an elastic lever arm to which the drum sealing element and/or the stationary sealing element is attached.

[0029] A dryer as claimed in claim 11 is particularly robust and can be manufactured economically. The retracting mechanism can be configured to retract the drum sealing element. The drum sealing element and/or an actuation weight that is attached to the retracting mechanism can be configured such that the rotational movement of the drum causes a centrifugal force that switches the retracting mechanism from the closed state to the open state. Preferably, the retracting mechanism is actuated when a certain threshold rotation speed, in particular above a drying speed and below a spinning speed of the drum, is exceeded.

[0030] A dryer as claimed in claim 12 can be operated particularly efficient. The feedback device preferably comprises a sensor, in particular a pressure sensor and/or a temperature sensor and/or a humidity sensor for detecting the air flow within the housing and/or the tub and/or the drying unit and/or the sealing air supply. The feedback device can be connected to the control unit. Preferably, the control unit is configured to control the sealing air flow depending on a signal from the feedback device. Preferably, the feedback device is arranged downstream of and/or at the flow restriction. By this, the feedback device can detect whether drying air passes the flow restriction. Preferably, the control unit is configured such that it can control the sealing air flow to avoid the drying air passing the flow restriction and to reduce sealing air consumption.

[0031] A further object of the present invention is to provide a method of operating the dryer that leads to less energy consumption and wear.

[0032] This object is achieved in accordance with the invention by a method of operating a dryer according to claim 13. The method as claimed in claim 13 can comprise any of the aforementioned features regarding the dryer. The flow restriction can be configured to guide the flow of drying air through the drum. Preferably, the drying air is conducted into the drum through at least one drum inlet port, like a drum laundry opening and/or through perforations in a cylindrical wall of the drum. By means of the flow restriction, flow of the drying air around the drum can at least partially be suppressed. The method of operating the dryer thus increases the drying air flow through the drum and the laundry, whereby the drying process is particularly efficient.

[0033] A method as claimed in claim 14 allows to reduce wear. Preferably, the retraction of the respective sealing element is induced by centrifugal forces. The closing movement can be induced by elastic forces, which are preferably provided by means of a bias spring. A respective sealing element can also be retracted by means of a retracting drive. Preferably, the drum sealing element and/or the stationary sealing element is retracted in a spinning phase and/or when a threshold rotation speed of the drum is reached, particularly exceeded. By this, damage of the flow restriction due to vibrations during the spinning phase can be avoided.

[0034] The method as claimed in claim 15 is particularly efficient. Mixing cold sealing air with moist drying air saves energy that is necessary for cooling the moist drying air within a condenser of the drying unit. Further, a more uniform temperature reduction within the moist drying air can be obtained and moisture can be removed from the moist drying air within the condenser more efficiently. Preferably, the cold sealing air is mixed with the moist drying air outside of the drum.

[0035] Further features, advantages and details of the invention result from the subsequent description of several exemplary embodiments. In the drawings:

Fig. 1

shows a sectional view of a washer dryer for washing and drying laundry according to a first embodiment, comprising a flow restriction between a drum and a tub for partial suppression of the drying air flow between the drum and the tub and a sealing air supply for providing sealing air at the flow restriction,

Fig. 2

shows the flow restriction and a sealing air inlet port of the sealing air supply in Fig. 1 in more detail,

Fig. 3

shows a perspective view of the drum in Fig. 1 with a drum sealing element of the flow restriction,

Fig. 4

shows a fluid diagram of the washer dryer in Fig. 1, comprising a drying unit for providing drying air for drying the laundry,

Fig. 5

shows a perspective view of a washer dryer according to a second embodiment, comprising a retracting mechanism for reversibly moving the drum sealing element to a retracted position, wherein the drum sealing element is arranged such that its mass causes a centrifugal force that retracts the drum sealing element when the drum is rotated,

Fig. 6a

shows a schematic side view of the retracting mechanism in Fig. 5, wherein the flow restriction is arranged in a closed state,

Fig. 6b

shows a schematic front view of the retracting mechanism in Fig. 6a,

Fig. 7a

shows a schematic side view of the retracting mechanism in Fig. 5, wherein the flow restriction is arranged in an open state,

Fig. 7b

shows a schematic front view of the retracting mechanism in Fig. 7a,

Fig. 8

shows a schematic side view of a retracting mechanism of a washer dryer according to a third embodiment, wherein the retracting mechanism is arranged in a closed state and comprises an actuation mass for causing a centrifugal force for retracting the drum sealing element when the drum is rotated,

Fig. 9

shows a schematic side view of the retracting mechanism in Fig. 8, wherein the retracting mechanism is arranged in an open state,

Fig. 10

shows a sectional view of a dryer for drying laundry according to a fourth embodiment, comprising flow restrictions between a drum and a housing,

Fig. 11

shows a schematic side view of a flow restriction at a back side of a drum, and

Fig. 12

shows a flow restriction at a front side of the drum.

[0036] The washer dryer 1 as shown in Fig. 1 to Fig. 4 comprises a tub 2 for receiving rinsing water and a drum 3 for receiving laundry 4, which is rotatably arranged in the tub 2. The tub 2 is arranged in a housing 5. A laundry port 6 of the housing 5 is reversibly closed by means of a cover 7. For loading the drum 3 with the laundry 4 the tub 2 comprises a tub laundry opening 8 and the drum 3 comprises a drum laundry opening 9. A gap between the laundry port 6 and the tub laundry opening 8 is closed by means of a shape flexible laundry port seal 10.

[0037] The tub 2 is attached to the housing 5 by means of springs 11 and dampers 12. The transmission of vibrations caused by the rotating drum 3 to the housing 5 can thus be reduced.

[0038] A drive unit, which is not shown in the figures, is torque-transmitting connected to the drum 3. The drive unit comprises an electric motor that is connected to a drive shaft 13 by means of a drive belt. The drive shaft 13 is attached to the drum 3, in particular to a back side 14 of the drum 3.

[0039] The drum 3 has two face sides, the back side 14 and a front side 15. The drum laundry opening 9 is located at the front side 15. A cylindrical wall 16 connects the front side 15 with the back side 14. The cylindrical wall 16 comprises drum inlet ports 17, in particular through holes that are permeable for gases and liquids. Particularly, the drum inlet ports 17 allow for the removal of water from the laundry 4 in a spinning phase of the washer dryer 1.

[0040] The tub 2 comprises a tub inlet port 18 for receiving drying air A_D and a tub outlet port 19 for discharging moist drying air A_M. A drying unit 20 of the washer dryer 1 is air-conductively connected to the tub inlet port 18 and to the tub outlet port 19. The drying unit 20 provides drying air A_D for drying the laundry 4. The drying air flow between the tub inlet port 18 and the tub outlet port 19 is indicated by arrows with the reference sign 21.

[0041] A first part of the drying air A_D flows from the tub inlet port 18, which is identical with the tub laundry opening 8 to the drum laundry opening 9 through the drum 3 and over the laundry 4 to the back side 14 of the drum 3, particularly to a drum outlet port 22. Hence, the drum laundry opening 9 forms a drum inlet port. The drum outlet port 22 is covered by a gas permeable grid 23. The moist drying air A_M flows through that grid 23 to the tub outlet port 19.

[0042] A second part of the drying air A_D is conducted from the tub inlet port 18 through a gap between the tub 2 and the drum 3 and through the cylindrical wall 16, in particular the drum inlet ports 17, into the drum 3 and to the laundry 4. The moist drying air A_M flows through the grid 23 and the drum outlet port 22 to the tub outlet port 19 of the tub 2.

[0043] A flow restriction 24 is arranged between the drum 3 and the tub 2, which at least partially suppresses the drying air flow 21 between the drum 3 and the tub 2. The flow restriction 24 is located at the back side 14, particularly at an edge between the back side 14 and the cylindrical wall 16.

[0044] The washer dryer 1 further comprises a sealing air supply 25, which provides sealing air As at a sealing air inlet port 26 of the tub 2. The sealing air flow is indicated by arrows with the reference sign 27. A first part of the sealing air flow 27 is conducted from the sealing air inlet port 26 through the drum inlet ports 17, the drum 3 and the drum outlet port 22 to the tub outlet port 19. A second part of the sealing air flow 27 is conducted along the back side 14 to the tub outlet port 19.

[0045] In Fig. 2 the flow restriction 24 is shown in more detail. The flow restriction 24 comprises a drum sealing element 28 that is attached to the drum 3, in particular to the back side 14, and a stationary sealing element 29 that is attached to the tub 2. The flow restriction 24 is a labyrinth seal. The drum sealing element 28 and stationary sealing element 29 act together to form the flow restriction 24, particularly the labyrinth seal.

[0046] The sealing air inlet port 26 is located at the stationary sealing element 29. The sealing air inlet port 26 comprises one channel or multiple channels which open into a distribution chamber 26'. The distribution chamber 26' has a circular shape or a volute / scroll like shape around a rotational axis 31 of the drum 3. The distribution chamber 26' distributes the sealing air As to a sealing air outlet opening 30. This sealing air outlet opening 30 has a circular shape around the rotational axis 31. The sealing air outlet opening 30 is located at a groove 32 between two adjacent teeth 33 of the flow restriction 24, in particular the tub sealing element 29.

[0047] In Fig. 3 the drum 3 with the drum sealing element 28 is shown in more detail. The drum sealing element 28 is attached to the back side 14 at a radial outermost position. The drum sealing element 28 comprises two circular teeth 33 between which a groove 32 is formed and which are arranged concentric to the rotational axis 31.

[0048] The teeth 33 of the drum sealing element 28 interlock with the teeth 33 of the stationary sealing element 29. In particular, the teeth 33 of the drum sealing element 28 and the stationary sealing element 29 overlap each other in a radial direction with regard to the rotational axis 31.

[0049] A fluid diagram, which shows the drying air flow 21 and the sealing air flow 27 within the washer dryer 1 is shown in Fig. 4. In Fig. 4 also the drying unit 20 and the sealing air supply 25 are shown in more detail.

[0050] The drying unit 20 comprises a condenser 34 for condensing out moisture from the moist drying air A_M, a fan 35 for circulating the drying air A_D and a heater 36 for heating the drying air A_D from the condenser 34. The condenser 34 is air-conductively coupled to the tub outlet port 19 of the tub 2. The fan 35 is connected to the condenser 34 and the heater 36 is connected to the fan 35. An outlet port of the heater 36 is air-conductively connected to the tub inlet port 18 of the tub 2.

[0051] The sealing air supply 25 comprises at least a sealing air duct 37. The sealing air duct 37 connects an overpressure area downstream the fan 35 with the sealing air inlet port 26. Preferably, the sealing air supply 25 further comprises a sealing air valve 38, which reversibly connects the fan 35 with the sealing air inlet port 26 air-conductively.

[0052] More preferably, the sealing air supply 25 further comprises a feedback device 39 for detecting the drying air flow 21 and/or the sealing air flow 27. The feedback device 39 comprises a temperature sensor for detecting the temperature of the air flow between the back side 14 of the drum 3 and the tub 2.

[0053] The washer dryer 1 comprises a control unit 40 for controlling the washing process and/or the drying process. The drying unit 20, in particular the condenser 34, the fan 35 and the heater 36, and the sealing air supply 25, particularly the sealing air valve 38, and the feedback device 39 are in signal connection with the control unit 40. In particular, the control unit 40 is configured such that it can reversibly activate the drying unit 20, in particular the condenser 34, the fan 35, the heater 36, and the sealing air supply 25, in particular the sealing air valve 38. The control unit 40 is further configured such that it can operate the sealing air valve 38 depending on a signal from the feedback device 39, in particular on the temperature of the air flow between the tub 2 and the drum 3. The control unit 40 is also in signal connection with the drive unit. The control unit 40 completely controls the washing and drying phases.

[0054] The functionality of the washer dryer 1, in particular of the drying unit 20, the flow restriction 24 and the sealing air supply 25, is as follows:
In an initial state, the drum 3 is loaded with laundry 4 through the laundry port 6, which is closed by the cover 7. A washer dryer 1, particularly the control unit 40, is activated and starts a washing process according to a selected washing program. Therefore, a water management system is activated and water is conducted into the tub 2. Depending on the specific washing phase, the water within the tub 2 is heated and/or detergents are added. The control unit 40 provides a signal for activating the drive unit and the drum 3 is rotated about the rotational axis 31 within the tub 2 for washing the laundry 4.

[0055] After finishing the washing phase, the rinsing water is conducted to a drain. The control unit 40 initiates a spinning phase. The drum 3 is rotated within the tub 2 by means of the drive unit at a high rotational speed. Due to centrifugal forces, water within the laundry 4 is expelled in a radial direction and ejected through the drum inlet ports 17. The drum 3 is stopped by means of a signal from the control unit 40. The ejected water is conducted to the drain. The spinning phase is finished.

[0056] Due to the configuration of the flow restriction 24 in the form of a non-contact labyrinth seal, any vibration of the drum 3 relative to the tub 2 cannot harm or damage the flow restriction 24. Particularly, a gap 41 between two adjacent teeth 33 is configured such that the vibrations do not result in a contact, particularly an impact, of the adjacent drum sealing element 28 and stationary sealing element 29, particularly the adjacent teeth 33. In a radial and an axial direction, the size of each gap 41 between adjacent, overlapping teeth 33 is in a range between 1 mm and 5 mm.

[0057] The drying phase is initiated by means of the control unit 40. The control unit 40 activates the drying unit 20. The fan 35 circulates air through the tub 2, between the tub inlet port 18 and the tub outlet port 19, in particular through the drum 3. Downstream the fan 35, in particular between the fan 35 and the tub inlet port 18, the air is heated by means of the heater 36 in order to provide heated drying air A_D at the tub inlet port 18. Within the drum 3, the heated drying air A_D removes moisture from the laundry 4. The moist drying air A_M is conducted through the drum outlet port 22 and the tub outlet port 19 of the tub 2 back into the drying unit 20, in particular the condenser 34. Within the condenser 34, the moist drying air A_M is cooled.

[0058] Thereby, the moisture within the drying air condenses and is removed. The dried air is aspirated into the fan 35 for recirculation.

[0059] By means of the drive unit, the drum 3 is rotated relative to the tub 2 during the drying phase. Thus, the drying efficiency is increased. Due to the rotation of the drum 3 relative to the tub 2 and to the configuration of the flow restriction 24 in the form of a non-contact labyrinth seal, there is a remaining gap 41 between the drum 3 and the tub 2. In other words, the back side 14 of the drum 3 is not sealed against the tub 2 completely gas-tight. Thus, heated drying air A_D would be able to flow around the drum 3, particularly along the cylindrical wall 16 and the back side 14 without passing the inside of the drum 3 and thus the laundry 4.

[0060] The feedback device 39 monitors the air flow between the back side 14 and the tub 2, particularly its temperature. The control unit 40 compares the temperature measured by means of the feedback device 39 with a specific threshold temperature. When the measured temperature reaches the threshold temperature, the control unit 40 notices that heated drying air A_D flows around and not through the drum 3. The sealing air valve 38 is then opened or an opening of the sealing air valve 38 is increased such that a flow rate of the sealing air As, which is conducted to the sealing air inlet port 26, is increased. The sealing air valve 38 preferably is an adjustable electric valve, preferably a continuously adjustable valve. The sealing air duct 37 is connected to an outlet port of the fan 35. The sealing air supply 25 does provide pressured dry air from the drying unit 20. Particularly, the sealing air duct 37 is a bypass duct, which allows to use non-heated dry air for sealing the flow restriction 24.

[0061] The sealing air As is used to increase the static pressure in the area of the flow restriction 24. The heated drying air A_D is thus forced not to flow around the drum 3 but to flow through it and thus pass the laundry 4.

[0062] The feedback device 39 is surrounded by the sealing air As. The control unit 40 does recognize a reduced temperature. An opening of the sealing air valve 38 can thus be decreased. The consumption of sealing air As and heated drying air A_D can thus be reduced and the efficiency of the drying process can be increased.

[0063] The threshold temperature is preferably adapted to the drying air temperature of the selected drying program. The control unit 40, the sealing air valve 38 and the feedback device 39 represent a control system with a closed control loop.

[0064] As an alternative, the sealing air supply 25 only comprises the sealing air duct 37 but not a sealing air valve 38 or a feedback device 39. Such sealing air supply 25 is specifically robust and can be manufactured highly economically. According to an aspect of the invention, the sealing air duct 37 comprises a static duct resistance element for setting the sealing air flow.

[0065] After the laundry 4 is dried, the drive unit, the drying unit 20 and the sealing air supply 25 are deactivated. The condensed water is conducted to the drain. The washer dryer 1 is deactivated and the dried laundry 4 can be removed from the drum 3.

[0066] The cold sealing air As is at least partially mixed with the heated moist drying air A_M within the tub 2. This is due to the fact that the sealing air As as well as the moist drying air A_M are discharged over the tub outlet port 19.

[0067] Since mixing of the cold sealing air As and the heated moist drying air A_M already takes place within the tub 2, the temperature of the moist drying air A_M is decreased already before it enters the condenser 34. Thus, less energy is necessary for cooling the moist drying air A_M within the condenser 34. The extraction of the moisture from the moist drying air A_M is particularly energy-efficient.

[0068] A further embodiment of the washer dryer 1 is shown in Fig. 5 to Fig. 7b. In contrast to the aforementioned embodiment, the washer dryer 1 comprises a retracting mechanism 42 for reversibly moving at least one of the sealing elements, in particular the drum sealing element 28, to a retracted position. The retracting mechanism 42 states an independent aspect of the invention, which nevertheless can be combined with the features of the aforementioned embodiment.

[0069] The retracting mechanism 42 comprises a lever arm 43, which is attached to the back side 14 of the drum 3 by means of a hinge 44. The drum sealing element 28 is attached to the end of the lever arm 43 which is opposite to the hinge 44.

[0070] The retracting mechanism 42 is shown in Fig. 6a to Fig. 7b in more detail. In Fig. 6a and Fig. 6b the flow restriction is shown in a closed state, particularly in a resistance position. In Fig. 7a and Fig. 7b, the flow restriction is shown in an open state, particularly in a retracted position.

[0071] The retracting mechanism 42 comprises a bias spring 45 for pretensioning the lever arm 43, particularly the drum sealing element 28 to the restriction position. The bias spring 45 is a coil spring. The bias spring 45 is arranged concentric to the rotational axis 31.

[0072] The retracting mechanism 42 is designed such that it retracts the drum sealing element 28 due to a centrifugal force generated by the rotating drum 3. In particular, the mass of the drum sealing element 28 and of the lever arm 43 are configured such that the retracting mechanism 42 moves from the closed state to the open state when a certain rotation speed of the drum 3 is reached. Damage of the flow restriction 24 due to increased vibrations at higher rotation speeds can thus be avoided.

[0073] In order to reduce circumferential stresses, which result from the movement of the retracting mechanism 42, the lever arm 43 is divided in multiple lever arm sections 46 and the drum sealing element 28 is divided in multiple drum sealing element sections 47. The drum sealing element 28 and the lever arm 43 are divided in a radial direction with respect to the rotational axis 31. As shown in Fig. 7b, this division results in a wedge-shaped gap 48 between adjacent lever arm sections 46 in the open state. These wedge-shaped gaps 48 are closed in the closed state. In the closed state, the flow restriction 24 is thus effectively obtained.

[0074] The functionality of the washer dryer 1 that is shown in Fig. 6a to Fig. 7b corresponds to the functionality of the aforementioned embodiment. During the spinning phase of the drum 3, the centrifugal forces at the drum sealing element 28 and at the retracting mechanism 42 surpass a threshold force which is needed to move the retracting mechanism 42 from the closed state to the open state. The pretensioning force of the bias spring 45 is overcome and the retracting mechanism 42 is moved from the closed state to the open state. The threshold rotation speed is above a drying speed and below a spinning speed of the drum 3. Damage of the flow restriction 24 due to vibrations or impacts is thus avoided.

[0075] During the drying phase, the drum 3 rotates at lower rotation speeds. The forces that are created by the circumferential bias spring 45 outweigh the centrifugal forces and the drum sealing element 28 is kept in the closed state.

[0076] Another embodiment of the washer dryer 1 is shown in Fig. 8 and Fig. 9. Compared to the aforementioned embodiments, the washer dryer 1 comprises an alternative retracting mechanism 42. The retracting mechanism 42 is attached to an edge between the back side 14 and the cylindrical wall 16 of the drum 3. The retracting mechanism 42 comprises a lever arm 43 that is connected to a hinge 44 and to the drum sealing element 28 and a counter lever arm 49 that is rigidly connected to the lever arm 43 and to a counterweight 50 that faces the hinge 44. The counterweight 50 is also referred to as actuating mass. A bias spring 45 is arranged such that it acts on the counter lever arm 49.

[0077] The counterweight 50 is configured such that the retracting mechanism 42 moves from a closed state to the open state due to centrifugal forces that act on the counterweight 50 due to the rotation of the drum 3. Particularly, the bias spring 45 and the counterweight 50 are configured such that the retracting mechanism 42 and the drum sealing element 28 stay in the closed state until a specific threshold rotation speed of the drum 3 is reached. By surpassing this threshold rotation speed, the retracting mechanism 42 moves to the open state and the flow restriction 24 is prevented from damage due to increased vibrations. The threshold rotation speed is above a drying speed and below a spinning speed of the drum 3.

[0078] The functionality of the washer dryer 1 that is shown in Fig. 8 and Fig. 9 corresponds to the functionality of the aforementioned embodiments. In contrast to the embodiment that is shown in Fig. 5 to Fig. 7b, the drum sealing element 28 moves from the closed state to the open state with an inwardly directed motion component.

[0079] The washer dryer 1 according to the invention is particularly robust and can be operated particularly energy-efficient. The flow restriction 24 at least reduces the drying air flow 21 which bypasses the drum 3 and thus prevents the waste of heating energy. The sealing air supply 25 further reduces the drying air flow 21 which bypasses the drum 3. The retracting mechanism 42 allows for disengaging the at least one sealing element 28, 29, in particular the drum sealing element 28, from the stationary sealing element 29, in order to avoid damage due to vibrations.

[0080] A further embodiment is shown in Fig. 10 to Fig. 12. In contrast to the aforementioned embodiments, the dryer 1 just serves to dry the laundry 4 and has no washing function. The drum 3 is rotatably arranged in the housing 5. The housing 5 comprises a mounting part 5' which is arranged at the front side 15 of the drum 3. The drum inlet ports 17 are arranged at the back side 14. The drum inlet ports 17 are arranged in a circular manner. The heater 36 is arranged above a horizontal plane, which comprises the rotational axis 31, and at the back side 14 near the drum inlet ports 17. In contrast thereto, the drum outlet port 22 is arranged at the front side 15 and below the cover 7 and the horizontal plane such that the drying air flow 21 has to cross the interior of the drum 3 and to pass the laundry 4. The drum outlet port 22 is connected to a filter 51. The filter 51 serves to filter out bluff balls.

[0081] A first flow restriction 24 is arranged at the back side 14, whereas a second flow resistance 24' is arranged at the front side 15.

[0082] Figure 11 shows the first flow restriction 24 in detail. The drum sealing element 28 has a wedge-shaped tooth 33. The drum sealing element 28 interacts with the stationary sealing element 29, which is attached to a mounting part 5" of the housing 5. The stationary sealing element 29 comprises sealing elements 33'. In figure 11, the sealing elements 33' abut against both sides and the top of the wedge-shaped tooth 33. However, it is also possible that the sealing elements 33' and the tooth 33 form a gap between each other. Preferably, the sealing elements 33' comprise a resilient material. The sealing elements 33' form the distribution chamber 26' and the sealing air outlet opening 30 to provide the sealing air flow 27. The distribution chamber 26' and the sealing air outlet opening 30 have a circular shape. The sealing air inlet port 26 opens into the distribution chamber 26'. In case of a gap between the drum sealing element 28 and the stationary sealing element 29 the sealing air flow 27 seals the flow restriction 24 such that the drying air A_D is guided to the drum inlet ports 17.

[0083] Figure 12 shows the second flow restriction 24' in detail. The drum sealing element 28 comprises a tooth 33. The drum sealing element 28 interacts with the stationary sealing element 29 which is attached to the mounting part 5'. The stationary sealing element 29 comprises sealing elements 33'. Preferably, the sealing elements 33' comprise an elastic material. The stationary sealing element 29 forms the circular distribution chamber 26' and the circular sealing air outlet opening 30. In figure 12, the tooth 33 abuts against the sealing elements 33'. However, it is also possible that the tooth 33 and the sealing elements 33' form a gap between each other. In case of a gap, the sealing air flow 27 seals the flow restriction 24' such that the drying air A_D is guided to pass the laundry 4 and the moist drying air A_M is guided to enter the drum outlet port 22. The distribution chamber 26' formed by the sealing elements 33' and/or the distribution chamber 26' formed by the stationary sealing element 29 can have a volute / scroll like shape and/or a circular shape.

Claims

1. Dryer for drying laundry, comprising

- a drum (3) for receiving the laundry (4), with

-- at least one drum inlet port (17) for receiving drying air (A_D), and

-- at least one drum outlet port (22) for discharging moist drying air (A_M),

- a drying unit (20) for providing the drying air (A_D) for drying the laundry (4), which is air-conductively connected to the at least one drum inlet port (17) and the at least one drum outlet port (22),

characterized by
a flow restriction (24, 24'), in particular a labyrinth seal, for guiding the drying air (A_D) to the at least one drum inlet port (17) and/or to the laundry (4) and/or from the drum (3) to the at least one outlet port (22).

2. Dryer according to claim 1, characterized by a sealing air supply (25) for providing sealing air (As) to guide the drying air (A_D) to the at least one drum inlet port (17) and/or to the laundry (4) and/or from the drum (3) to the at least one outlet port (22).

3. Dryer according to claim 1 or 2, characterized in that the drum (3) has two face sides (14, 15), wherein a flow restriction (24, 24') is located at at least one of face sides (14, 15).

4. Dryer according to any of the preceding claims, characterized in that the drum outlet port (22) for the moist drying air (A_M) is located at a face side (14, 15) of the drum (3).

5. Dryer according to any of the preceding claims, characterized in that at least one sealing air inlet port (26) of the sealing air supply (25) is located at the flow restriction (24, 24').

6. Dryer according to any of the preceding claims, characterized in that at least one sealing air outlet opening (30) of the sealing air supply (25) is arranged in a circular manner and/or has a circular shape around a rotational axis (31) of the drum (3).

7. Dryer according to any of the preceding claims, characterized in that the drying unit (20) comprises a condenser (34) for drying the moist drying air (A_M) and a heater (36) for providing heat to the drying air (A_D) , wherein in particular the sealing air supply (25) connects a drying air duct of the drying unit (20) between a fan (35) and the heater (36) with at least one sealing air inlet port (26) to provide non-heated, dry sealing air (A_S).

8. Dryer according to any of the preceding claims, characterized in that the flow restriction (24) comprises a drum sealing element (28) that is attached to the drum (3) and/or a stationary sealing element (29).

9. Dryer according to claim 8, characterized by at least one retracting mechanism (42) for reversibly moving the drum sealing element (28) and/or the stationary sealing element (29) to a retracted position.

10. Dryer according to claim 9, characterized in that the retracting mechanism (42) comprises at least one bias spring (45) for pretensioning the drum sealing element (28) and/or the stationary sealing element (29) to a restriction position.

11. Dryer according to claim 9 or 10, characterized in that the retracting mechanism (42) is designed such that it retracts the drum sealing element (28) due to a centrifugal force that is caused by the rotating drum (3).

12. Dryer according to any of the preceding claims, characterized in that the sealing air supply (25) comprises a feedback device (39) for detecting the drying air (A_D) and/or the sealing air (A_S).

13. Method of operating a dryer (1) comprising the steps:

- providing a dryer (1) according to at least one of the preceding claims,

- conducting drying air (A_D) through the drum (3) by means of the flow restriction (24, 24') for drying the laundry (4).

14. Method according to claim 13, characterized by moving a drum sealing element (28) and/or a stationary sealing element (29) of the flow restriction (24, 24') to a retracted position.

15. Method according to claim 13 or 14, characterized by mixing cold sealing air (As) with moist drying air (A_M) .

Drawing