EP1449953B1 - Drying device for laundry and corresponding method - Google Patents

Description

The invention relates to a drying device for laundry with a stationary housing shell and a rotatably mounted therein and peripherally perforated to the air passage inner drum for receiving laundry to be dried as well as a connected to the housing jacket, a heating register-containing air duct for the supply and discharge of drying air ,

In most cases, such a drying device is designed as a single-chamber machine with a stationary housing shell and an inner drum driven in rotation about a substantially horizontal drum axis. As a rule, the inner drum consists of a hollow cylinder or tubular jacket made of perforated stainless steel sheet, which is closed at its inner axial end by a stainless steel sheet forming the inner drum rear wall. This can be designed as a discharge door. The front end bounding the other end has a central filling opening for the laundry item to be dried, which is closed only after being filled by a door hinged to the outer housing. During the drying process, the inner drum surrounding the laundry item is kept in rotation in order to loosen up the laundry items and to disperse the laundry items of the laundry item as evenly as possible from the flow of the drying air.

In a conventional single-chamber machine, the individual processes of the drying process in the same inner drum run one behind the other. These are essentially the shaking of the previously dehydrated, introduced into the inner drum laundry, their heating, their drying and the necessary before washing removal cooling. Cooling is necessary for safety reasons, because the drying process with up to approx. 150 ° hot air is carried out and only the cooling process allows a safe further handling of the laundry. It may therefore be possible to open the door to the laundry only after a cooling of the laundry to a safe limit temperature. After loading with a new batch of laundry, the dryer is reheated. Especially since the drying of each laundry item not only the laundry itself, but also parts of the drying device must be heated and cooled again, the operation of a single-chamber machine with comparatively high time and energy consumption is connected.

In particular, in the commercial sector, for example in a large laundry, multi-chamber drying devices are therefore used, in which the heating, the drying process and the final cooling process take place spatially separated and the laundry items to be dried are conveyed in each case after completion of an operation in a flow belt, so that the individual chambers or areas of the drying device can be maintained at a substantially constant operating temperature. Such a drying device is for example from the EP 1 054 094 A1 known.

DE 19 913 938 discloses a drying device according to the preamble of claim 1.

The known drying device comprises an inner drum subdivided axially into a plurality of inner drum chambers, namely a heating chamber, a drying chamber and a cooling chamber. The inner drum is formed from two juxtaposed half-shells, of which a first half-shell for conveying the laundry items relative to the second half-shell is slidable by one chamber width in the axial direction. The axial displacement of the first half-shell takes place, preferably in a rest position, when it is in relation to the inner drum rotation in the bottom dead center, and thus absorbs the pulled down due to gravity laundry. After the axial displacement, the inner drum is rotated by 180 °, so that the laundry falls back around an inner drum chamber in the stationary second half-shell falls. At the same time, the laundry item previously taken up in the last inner drum chamber in the laundry conveying direction is ejected from the inner drum, and a new laundry item to be dried is opened in the open, in Laundry conveying direction first inner drum chamber introduced. After the axial retraction of the first half-shell, a new cycle of operation is initiated.

The known drying device is equipped for better utilization of heat with a working according to a countercurrent principle air duct, in which the inner drum chambers are integrated against the laundry conveying direction. The drying air flow thus first flows through the cooling chamber, where the cold drying air is preheated by the residual heat of the laundry charge received there. The drying air is then heated to a drying temperature, and flows through the drying chamber and then the heating chamber. To further improve the energy balance, a portion of the drying air in a circulation flow is repeatedly passed through the respective inner drum chamber in each inner drum chamber. In addition, the residual heat of the effluent from the cooling chamber exhaust air is recovered via a heat exchanger.

The invention has for its object to improve a drying device of the type mentioned in terms of applied for the drying process time and energy costs. The invention is furthermore based on the object of specifying a method which is particularly suitable for operating such a drying device.

With regard to the drying device, the object is achieved according to the invention by the features of claim 1. With regard to the method, the object is achieved by the features of claim 10. Thereafter, at least one sensor is provided, which continuously receives relevant measurements for determining the residual moisture of a laundry item and at a provided for controlling the drying process control unit transmitted. On the basis of the recorded measured variables, the residual moisture content of the laundry item is continuously determined and compared with a desired value, based on the comparison result the heating of the drying air flow and / or the duration of the drying process is regulated.

The invention is based on the recognition that in each case a different time and energy expenditure is required for the drying of different laundry items, especially since laundry items can differ significantly by their weight and their textile nature. To prevent a particularly large or difficult-to-dry laundry item from being dried insufficiently, in a conventional uniform drying process, the drying temperature and drying time are always aligned to the maximum requirement. This inevitably leads to over-drying of mitbeförderten small or slightly drying laundry items and thus to unnecessary Energieund time consumption. The basic idea of the invention is to adapt the drying time and the applied energy as far as possible to the needs of each individual laundry item. For this purpose, a control of the heating register is provided as a function of currently determined, the laundry items associated with actual values. As a particularly advantageous control variable for determining needs, it draws the residual moisture content of a laundry item to be dried.

As for the determination of the residual moisture relevant data, the temperature and / or the humidity in the drying air flow are preferably used. Suitable sensors are expediently arranged either on the inside of the housing shell or in an air outlet duct of the air duct. A particularly precise determination of the residual moisture of the laundry item is made possible by the fact that the humidity and / or the temperature of the drying air discharged from the laundry item is compared with the humidity or the temperature of the drying air supplied to the laundry item, in particular by determining the temperature difference. In this way, the moisture absorption of the drying air flow and its temperature change can be determined specifically. To control the drying process, the control unit expediently acts on the arranged in the air duct heater and the movement drive the inner drum.

The demand-adjusted control of the drying capacity is already advantageous to apply in a simple single-chamber machine. However, the advantages of this scheme are particularly evident in a drying device in which, to enable a streamlined, in particular flow belt-like, expiration of the drying process, the inner drum is divided into at least two axially consecutive inner drum chambers for receiving a respective laundry post. In a preferred embodiment, in this case three internal drum chambers are provided, is heated in a laundry in the direction of the first inner drum chamber of laundry items by hot drying air, takes place in a subsequent laundry in the direction of the inner drum drum, the actual drying process at high drying temperature and in the third inner drum chamber, the laundry is cooled by cold drying air , To achieve a particularly large laundry throughput, a laundry item is expediently heated, dried or cooled at the same time in each inner drum chamber, wherein after completion of the common operation cycle, a conveying phase follows, in which the laundry items are conveyed like a conveyor belt into the inner drum chamber following in the laundry conveying direction. For setting the different operating conditions for each inner drum chamber, the air guide is expediently designed such that a corresponding air supply channel and a corresponding Luftabführkanal are provided for each inner drum, so that in each inner drum chamber, a separate chamber air flow can be excited.

In order to accomplish the transport of a laundry item from an inner drum chamber into an inner drum chamber next to the laundry conveying direction with structurally simple means, an inner drum formed from two half shells is provided, wherein each half shell has at least one dividing wall dividing the inner space in the axial direction into at least two compartments to form the inner drum chambers , The half-shells are mutually mirror-inverted, so that corresponding partitions of the two Half shells in a juxtaposition adjoin one another in alignment, and thus form opposite compartments of the two half-shells together in each case a closed inner drum chamber. To promote a Wäschepostens a half shell relative to the other half-shell in the axial direction is displaceable. The promotion of the Wäschepostens takes place in a structurally particularly simple manner according to the above-described, from the EP 1 054 094 A1 known methods.

In an energy-saving manner, the inner drum chambers are advantageously integrated into the air duct according to a counterflow principle. The cold drying air stream first flows through the cooling chamber, i. the last in the laundry conveying direction inner drum chamber, and is thereby preheated by the residual heat of the recorded there laundry item. The preheated drying air stream is then heated by means of a heating register to a drying temperature and passed successively through the drying chamber and the heating chamber. To further improve the energy balance, the air discharge channel assigned to each inner drum chamber is connected to the corresponding air supply duct, so that part of the drying air flow can be passed through the inner drum chamber several times as a circulation flow. By the return of the drying air in particular their moisture absorption capacity is particularly well exploited, with only a comparatively small volume of air must be heated. In addition, this takes into account the fact that the required for loosening the laundry air flow is significantly higher than the air flow required for moisture removal.

In a particularly simple variant for adjusting the energy supply, the heating of the chamber air flow flowing through the drying chamber is set as soon as the residual moisture content of the laundry item received in the drying chamber falls below the nominal value. This leads to an energy saving, in particular, when, with a small batch of laundry to be dried, the full dry state is reached even before the end of the cycle. To Shutdown of the heater, the drying chamber is only flowed through by moderately warm drying air, whereby over-drying of the laundry cost is effectively avoided.

In an advantageous alternative control mechanism, the heating capacity of the heating register is controlled during the entire cycle of operation so that the drying process is adjusted in terms of its duration to the cooling process. In other words, the heating of the drying chamber flowing through the chamber air flow is controlled such that the residual moisture of the recorded laundry in the drying chamber reaches the setpoint at about the time at which the temperature of the recorded in the cooling chamber laundry costs reaches the limit temperature. The advantage of this method is that an overdrying and associated damage to the laundry laundry item to be dried and thus an increased energy consumption is anticipated avoided, at the same time the time required for drying and cooling is kept particularly low.

To increase the efficiency of the drying process, the process cycle is preferably terminated as soon as the residual moisture content of the laundry item received in the drying chamber has fallen below the nominal value and the temperature of the laundry item received in the cooling chamber has fallen below the limit temperature.

Fig. 1

in einem schematischen Querschnitt eine Trocknungseinrichtung mit einer drehbar gelagerten, zwei Halbschalen umfassenden Innentrommel,

Fig. 2

in einem schematischen Längsschnitt die Trocknungseinrichtung gemäß Fig. 1 in Gegenüberstellung der beiden Halbschalen,

Fig. 3

in einer Darstellung gemäß Fig. 2 die Trocknungseinrichtung mit zueinander versetzten Halbschalen,

Fig. 4

in einem schematischen Querschnitt die Trocknungseinrichtung gemäß Fig. 3 in um ca. 135° gedrehter Stellung der Innentrommel,

Fig. 5

in einer Darstellung gemäß Fig. 3 die Trocknungseinrichtung in um 180° gedrehter Stellung der Innentrommel,

Fig. 6

die Trocknungseinrichtung gemäß Fig. 5 wiederum in Gegenüberstellung der Halbschalen,

Fig. 7

in einem Längschnitt eine schematische Darstellung der Luftführung der Trocknungseinrichtung und

Fig. 8

eine Variante der Luftführung gemäß Fig. 7 in einer einem Fließdiagramm ähnlichen Darstellung mit in Querschnitten Vlla-Vllc gemäß Fig. 7 dargestellten Innentrommelkammern.

Embodiments of the invention will be explained in more detail with reference to a drawing. Show in it

Fig. 1

in a schematic cross section of a drying device with a rotatably mounted, two half-shells comprising inner drum,

Fig. 2

in a schematic longitudinal section according to the drying device Fig. 1 in juxtaposition of the two half-shells,

Fig. 3

in a representation according to Fig. 2 the drying device with mutually offset half-shells,

Fig. 4

in a schematic cross section of the drying device according to Fig. 3 in about 135 ° rotated position of the inner drum,

Fig. 5

in a representation according to Fig. 3 the drying device in 180 ° rotated position of the inner drum,

Fig. 6

the drying device according to Fig. 5 again in comparison of the half-shells,

Fig. 7

in a longitudinal section a schematic representation of the air flow of the drying device and

Fig. 8

a variant of the air duct according to Fig. 7 in a flowchart similar representation with in cross-sections Vlla-Vllc according to Fig. 7 illustrated inner drum chambers.

Corresponding parts are identified in the figures with the same reference numerals.

The core of the drying device is an inner drum 1. It is formed by two, each about half the circumference of the drum extending, independent half-shells 2.3. The half-shells 2, 3 in each case have the outline shape of a pipe section approximately half sectioned in its longitudinal direction with a relatively large pipe diameter, the end faces of the two pipe section halves being respectively closed by end walls 4, 5 or 6, 7 extending at right angles to the drum rotation axis 9, and wherein the pipe jacket or the two half-shells 2.3 associated with tube half-shells with holes 8 shown schematically for the flow through the inner drum 1 are provided with drying air. The perpendicular to the drawing plane of Fig. 1 running drum rotation axis 9 does not physically appear within the inner drum 1 or within their halves 2.3 and is only available as an imaginary line. The inner drum 1 is rotatably supported on its outer periphery between support rollers 10 within an outer drum 11 serving as a stationary housing jacket.

The half-shells 2, 3 are displaceable relative to one another by a displacement drive, which is not shown, acting only on one of the two half-shells - in this case the half-shell 2 -, with respect to the drum rotation axis 9. The axial displaceability of the half-shell 2 is in the Fig. 2, 3rd . 5 and 6 symbolically indicated by a double-headed arrow. The interior of each half-shell 2, 3 is between its end walls 4, 5 and 6, 7, respectively, by means of radial partitions 21, 22 and 23, 24 into three compartments 12-14 (half-shell 2) and 15-17 (half-shell 3, respectively) ) divided by the same compartment size. The compartments 12-14 and 15-17 are in the direction of the drum rotation axis 9 side by side. In the in the Fig. 2 and Fig. 6 shown aligned facing between the two half-shells 2.3 form the diametrically opposite compartments 12 and 15, 13 and16 and 14 and 17 of the half-shells 2.3 together each have an inner drum chamber 18 or 19 and 20. In the in Figures 2 and 6 illustrated comparison of the half-shells 2 and 3, the actual drying operations are completed, during which the inner drum 1 is rotated to uniformly suspend the recorded in the inner drum 1 laundry the drying air flow.

• Die Beschickung der Trocknungseinrichtung mit einem Wäscheposten 25 erfolgt gemäß der Wäscheförderrichtung 26 an der der Innentrommelkammer 18 angrenzenden Beschickungsseite 27. Der Auswurf der trockenen Wäsche erfolgt entsprechend an der an die Innentrommelkammer 20 angrenzenden Auswurfseite 28.

The loading of the drying device with individual laundry items 25 and their transport between the separate inner drum chambers 18, 19 and 20 and the unloading of a dried laundry item 25 will be described in detail below with reference to FIGS Fig. 3-5 described:

• The loading of the drying device with a laundry item 25 takes place according to the laundry conveying direction 26 on the feed side adjacent to the inner drum chamber 18. The dry laundry is ejected correspondingly to the ejection side 28 adjoining the inner drum chamber 20.

For loading as for ejection of laundry items 25, the half-shell 2 opposite to the half-shell 3 according to Fig. 3 axially displaced in the laundry conveying direction 26 by one compartment width. The for loading in their bottom dead center position located, axially fixed half-shell 3 is with its the feed side 27 facing compartment 15 on the end wall 6 of the located in top dead center, shifted half-shell 2 also ( Fig. 5 ). Thereby, the compartment 15 of the half-shell 3 is freely accessible from above, so that in the embodiment as a conveyor belt 29 formed feeding device unhindered in the space surrounded by the stationary outer drum 11 space above the compartment 15 of the half-shell 3 enter and leave a laundry item 25. This falls from above in the direction of arrow 30 in the compartment 15 into it. This laundry item 25 is in the form of a dewatered press cake, as it is given from a dewatering press on the conveyor belt 29.

After loading, the upper half-shell 2 according to Fig. 6 returned in full comparison with the half-shell 3, whereby the now closed again inner drum 1 completely rests within its sheath through the outer drum 11.

Within the, seen in the laundry conveying direction 26, the first inner drum chamber 18, which is also referred to below as Aufheizkammer 18, takes place under rotation of the inner drum 1 in the drying air flow L shaking and heating of the enclosed Wäschepostens 25. The middle, filled with a further Wäscheposten 25 inner drum chamber 19 or drying chamber 19 is the actual drying process at a drying temperature up to about 150 ° C. In the ejection side 28 facing, also referred to as the cooling chamber 20 inner drum chamber 20, the cooling of dried laundry items 25 takes place by cold drying air at or below a limit temperature, which is no longer a hazard for manual handling of the laundry. When the inner drum 1 rotates, the heating process associated with the initial loosening of the laundry, the drying process and the cooling process of several laundry items 25 occur simultaneously in the juxtaposed inner drum chambers 18-20.

To remove a dried and cooled laundry item 25, the rotary drive of the inner drum 1 is stopped in the bottom dead center position of the axially displaceable half-shell 2 ( Fig. 2 ). Thereafter, the half-shell 2 is first advanced in the laundry conveying direction 26 with respect to the half-shell 3. As a result of the offset of the half-shells 2, 3, the compartments 12 and 13 of the half-shell 2 are now diametrically opposite the compartments 16 and 17 of the half-shell 3. The adjoining the discharge side 28 compartment 14 of the half-shell 2 is open at the top over the end wall 7 of the half-shell 3 also ( Fig. 3 ). While maintaining this open position, the inner drum 1 is then rotated by a half turn corresponding to the direction of rotation 31. This is equivalent to the transfer of the axially displaceable half-shell 2 in a relation to the other half-shell 3 overhead position, as in Fig. 5 is shown. Fig. 4 indicates an intermediate position between the rotational positions according to Fig. 3 (Home position) and Fig. 5 (End position) of the ejection process. When pivoting the axially displaced half-shell 2 at the same time travels a collecting device 32 in the now released space below the compartment 14 into it. The collecting device is effective in the manner of a receiving tray into which the dried laundry item 25 falls from the swung-compartment 14 in the direction of arrow 33 down ( Fig. 4 ). The collecting device 32 is suitably connected to a conveyor which feeds the dry laundry to a next processing station (not shown). In the Fig. 5 shown ejection end position is at the same time the feed position for the new loading of the compartment 15. In the by the sequence of FIGS. 3 to 5 described half rotation of the inner drum 1 continues to fall depending on a laundry items from compartment 12 in compartment 16, as well as from compartment 13 in compartment 17. After the return movement of the half-shell 2 according to the sequence of FIGS. 5 and 6 Thus, the laundry item 25 previously received in the heating chamber 18 is now in the drying chamber 19, and also the laundry item 25 previously received in the drying chamber 19 is now in the cooling chamber 20.

By the drying device, it is possible to divide the drying process into several spatially separated individual steps, which are carried out step by step in the laundry conveying direction 26 side by side. Thus, it is not necessary to heat the inner drum 1 or portions thereof alternately and cool again. In the embodiment, three inner drum chambers 18-20 are arranged side by side in the same inner drum. Basically, however, it is already advantageous over a single-chamber machine to work with only two juxtaposed internal drum chambers 18,19. But it is also quite conceivable, instead of in the embodiment in the normal position total existing three side by side the inner drum 1 forming inner drum chambers 18-20 provide more than three inner drum chambers side by side and thereby make the drying process from the feed side 27 to the discharge side 28 in more than three steps ,

An air guide 34 within the dryer makes a special energy savings possible. It is especially in the in the Fig. 2 and 6 and 7 and 8 shown juxtaposition of the inner drum 1 effectively, ie outside the transport phase, and is based on the Fig. 7 and 8th described in more detail.

The air guide 34, ie the entire line device for the drying air, is designed such that each inner drum chamber 18,19,20 flows through separately from a chamber air flow L1, L2, L3. The chamber air streams L1 to L3 are part of a designed as a counter air flow drying air flow L. This means that the drying air flow L flows through all the inner drum chambers 18 to 20 in the direction of the laundry conveying direction 26 reverse order. The drying air flow L is removed as fresh air 35 of the ambient air and thus flows through the chamber airflow L1 first, the cooling chamber 20, as chamber airflow L2 then the drying chamber 19 and finally as chamber airflow L3 the heating chamber 18 before the drying air by means of a heat exchanger 36 withdrawn their inherent heat and her afterwards as exhaust air 37 again the ambient air or outside atmosphere is supplied.

The chamber air flow L1-L3 respectively exits from an air supply duct 38a-c brought to the outer drum 11 (parts corresponding to their subordinate parts 8a to 8c are specified by lower case letters) through the perforated jacket of the inner drum 1 into the corresponding inner drum chamber 18a. 20 and flows through the inner drum chamber 18-20 substantially radially. The chamber air stream L1-L3 is sucked out of the inner drum chamber 18-20 through an air discharge channel 39a-c opening into the outer drum 11 approximately opposite to the air feed channel 38a-c and passes through a filter 40a-c connected in the respective air discharge channel 39a-c and a drying air flow L accelerating fan 41 ac.

From each Luftabführkanal 39a-c branches at one on the pressure side of the fan 41 ac arranged line division 42a-c end connected to the corresponding Luftzuführkanal 38a-c circulation channel 43a-c, via which a part of the discharged chamber air flow L1-L3 as circulation flow Z1 Z3 can be returned to the associated internal drum chamber 18-20. By means of a respective pair of flaps or actuators 44a-c in each circulation channel 43a-c or downstream of the line division 42a-c in the air discharge channel 39a-c, it is controlled which portion of the chamber air flow L1-L3 as circulation flow Z1-Z3 in the same inner drum chamber 18th -20 is returned. This recirculated portion is on average about 60% of the respective chamber air flow L1-L3, but can be varied separately for each inner drum chamber 18-20 as needed. The remainder of an average of 40% of the chamber air flow L1-L3 is fed into the next in the air flow direction air supply duct 38a-b or, starting from the last in the air flow direction Luftabführkanal 39a as exhaust air 37 to the environment.

The drying air flow L thus takes from the ambient or fresh air 35 the following course: The fresh air 35, mixed with the recirculating through the circulation channel 43c circulation flow Z1 through the air supply channel 38c of the cooling chamber 20, where by heat exchange of the relatively cool chamber air flow L1 with the laundry received in the cooling chamber 20 on the one hand, the laundry cooled, and on the other hand, the drying air is preheated to a temperature between about 30 ° C and 80 ° C. The chamber airflow L1 exhausted through the air discharge passage 39c is returned to the cooling chamber 20 after being filtered by parts through the circulation passage 43c.

The remaining part of the chamber air flow L1 is further preheated in a heat exchanger 45 to about 80 ° C and mixed with the recirculating flow Z2 flowing back through the circulation passage 43b to form the chamber air flow L2. Depending on the volume fraction of the mixed circulation air, the temperature and the humidity of the chamber air flow L2 supplied through the air supply passage 38b to the drying chamber 19 vary, especially since the recirculating circulation flow Z2 is generally hotter and wetter than the drying air supplied from the cooling chamber 20. The chamber air flow L2 is additionally heated to a drying temperature of up to 150 ° C. by a heating register 46b arranged in the air supply channel 38b. The properties of the chamber air flow L2 with respect to temperature and humidity, and thus the drying intensity, can thus be adjusted in a targeted manner by regulating the admixing ratio of circulation air and regulating the heating power of the heating register 46b.

The chamber air stream L2 sucked out of the drying chamber 19 through the air discharge channel 39b and again filtered, is in turn fed back into the drying chamber 19 in parts through the circulation channel 43b. The remaining part of the chamber air flow L2 is mixed with the circulation flow Z3 flowing back through the circulation passage 43a to form the chamber air flow L3 and supplied to the heating chamber 18 via the air supply passage 38a. Means of one in the air supply channel 38a arranged second heating register 46a, the chamber air flow L3 is heated in turn beforehand to a temperature up to 150 ° C. The chamber air stream L3 extracted from the heating chamber 18 through the air discharge passage 39a is returned to the heating chamber 18 after being filtered by the circulation passage 43a. The remaining part of the chamber air flow L3 is passed through an additional filter 47, of a only in the embodiment according to Fig. 8 accelerated fan 48 and supplied to the heat exchanger 36. The heat extracted by the heat exchanger 36 is returned to the heat exchanger 45 for preheating the drying air flow L.

The in the Fig. 7 and 8th The embodiments of the drying device shown differ in that according to Fig. 8 the air discharge channel 39b-c associated with an upstream inner drum chamber 19, 20 opens directly into the downstream air supply channel 39a-b, while according to FIG Fig. 7 the air discharge passage 39b-c associated with an upstream drum drum chamber 19,20 initially discharges into the downstream following drainage passage 38a-b, and passes only via the fan 41 disposed therein and the branching circulation passage 43a-b into the air supply passage 38a-b.

The heating registers 46a-b are preferably supplied with heat by external steam 49, as is usually present in industrial laundries for heating purposes, in particular for the washing water. The heat converted in the heating registers 46a-b contains the majority of the amount of energy to be supplied to the drying device. In contrast, the electrical energy required to drive and control the drying device is low. A particularly expedient method for saving energy is therefore to adjust the heating of the heating coil as needed.

To determine needs, the drying device according to the Fig. 7 and 8th equipped with a sensor 50 arranged in the air discharge channel 39b, which continuously measures the air humidity and, optionally, the temperature of the drying air flowing out of the drying chamber 19. An arranged in the air supply passage 38b another sensor 51 measures the humidity and, optionally, the temperature of the drying air flowing into the drying chamber 19. A third sensor 52 arranged in the air discharge channel 39 c measures the temperature of the drying air flowing out of the cooling chamber 20. Further sensors, not shown in more detail, are optionally assigned in the same way to the air feed channel 38a and air discharge channel 39a, and thus to the heating chamber 18.

The sensors 50-52 supply the recorded measured values via a schematically illustrated data line 53 to a control unit 54 preferably designed as a program-controlled computer. The control unit 54 in turn controls the heating coils 46a-b, the valves 44a-c and an inner drum drive 56 for rotation and axial displacement of the inner drum 1 via a control line 55 shown schematically and simplified. The heating coils 46a-b are preferably adjustable continuously or in several steps between a maximum heating power and zero power. Likewise, the valves 44a-c are preferably continuous or can be adjusted in several steps.

In particular, two basic conditions are monitored by the control unit. On the one hand, the laundry must have reached a full drying state at the end of the drying process or, in other words, the residual moisture of the laundry lot 25 received in the drying chamber 19 must have reached or fallen below a predetermined desired value. On the other hand, the temperature of the laundry item 25 received in the cooling chamber 20 must have reached or fallen below the limit temperature which is safe for further handling.

To determine the residual moisture content of the laundry lot 25 received in the drying chamber 19, the control unit 54 calculates the moisture absorption by comparison of the humidity values displayed by the sensors 50 and 51 and, if present, the temperature change of the chamber air flow L2 by comparing the temperature values displayed by the sensors 50 and 51 when flowing through the drying chamber 19. From the moisture absorption With the aid of a stored calibration curve or model function, the control unit 54 calculates the residual moisture content of the laundry lot 25 received in the drying chamber 19. For a refined determination of the residual moisture, the control unit 54 optionally draws the temperature or temperature change of the chamber air flow L2.

In an analogous manner, the control unit 54 concludes from the temperature value reported by the sensor 52 to the temperature of the laundry load 25 received in the cooling chamber 20.

As soon as both of the above-mentioned basic conditions have been met, the control unit 54 aborts the cycle of operation by corresponding activation of the inner drum drive 56 and the air guide 34 and causes the conveyance of the laundry items 25 (FIG. Fig. 3 to 6 ). The respective duration of successive process cycles is thus different and tailored to the needs of each treated laundry items 25.

To prevent overdrying of a laundry item 25, two alternative control mechanisms are provided. In a first variant, the heating coil 46b is operated in normal operation with a comparatively high heating power. The heating power is, for example, regulated in such a way that a constant drying temperature is measured in the sensor 51. If the first basic condition is reached before the second time, that is, the laundry item 25 received in the drying chamber 19 is already dry before the laundry item accommodated in the cooling chamber 20 has cooled sufficiently, then the control unit 54 switches off the heating register 46b, whereby the moisture discharge the drying chamber 19 and the power consumption during the remaining drying period is lowered. Supportingly, the control unit 54 optionally changes the position of the valves 44b to further reduce the moisture discharge.

According to an alternative control mechanism, the time until the full-drying state is reached becomes the first basic condition of the cooling time in accordance with the second basic condition, by suitably adjusting the heating power of the heating register 46b. This is expediently achieved in that the control unit continuously or intermittently records the time course of the residual moisture of the laundry lot 25 received in the drying chamber 19, and calculates the probable time of fulfillment of the first basic condition with the aid of a stored calibration curve or model function. Similarly, the control unit 54 estimates from the time course of the temperature of the recorded in the cooling chamber 20 Wäschepostens 25 from the time for the fulfillment of the second basic condition. If the first basic condition before the second is reached on the basis of this estimation, then the heating power of the heating register 46b is regulated down accordingly. Otherwise, the heating power is increased. The last-described control mechanism thus optimizes the drying process to suit the required heating capacity and the duration of the drying process. LIST OF REFERENCE NUMBERS 1 inner drum 2.3 half shell 4-7 bulkhead 8th hole 9 Drum rotation axis 10 support rollers 11 external drum 12-17 compartment 18 Inner drum chamber = heating chamber 19 Inner drum chamber = drying chamber 20 Inner drum chamber = cooling chamber 21-24 partition wall 25 laundry batch 26 Laundry conveying direction 27 loading side 28 ejector side 29 conveyor belt 30 arrow 31 direction of rotation 32 catcher 33 arrow 34 air duct 35 fresh air 36 heat exchangers 37 exhaust 38a-c air supply duct 39a-c air discharge 40a-c filter 41a-c fan 42a-c line division 43a-c circulation channel 44a-c actuators 45 heat exchangers 46a-b heater 47 filter 48 fan 49 external steam 50-52 sensor 53 data line 54 control unit 55 control line 56 Interior drum drive L Dry air flow L1-L3 Chamber airflow Z1-Z3 Circulation air flow

Claims (15)

1. Drying device for laundry, comprising a stationary housing casing (11) and an inner drum (1), which is rotatably mounted in said housing casing, is provided with holes over the circumference thereof to allow air to pass through, and is intended for receiving laundry to be dried, and comprising an air duct (34) that is connected to the housing casing (11), contains a heating register (46a-b) and is intended for supplying and removing drying air, the inner drum (1) comprising at least two inner drum chambers (18-20) that are axially one behind the other and each receive a batch of laundry (25), and the air duct (34) comprising a corresponding air supply channel (38a-c) and a corresponding air removal channel (39a-c) for each inner drum chamber (18-20) such that a separate chamber airflow (L1-L3) can flow through each inner drum chamber (18-20),
   characterised in that
   a control unit (54) assigned to the heating register (46a-b) is connected to a sensor (50, 51, 52) on the data-input side in order to determine the residual moisture of the batch of laundry (25) in an inner drum chamber (19) formed as a drying chamber (19), and is connected to an inner drum drive (56) on the data-output side, the control unit (54) being designed to actuate the inner drum drive (56) such that the batch of laundry (25) is conveyed out of the drying chamber (19) by means of the inner drum drive (56) only after the residual moisture of the batch of laundry (25) is below a predeterminable threshold value.
2. Drying device according to claim 1, characterised in that the sensor (50) is designed as an air moisture sensor arranged inside the housing casing (11) and/or in an air removal channel (39a-c).
3. Drying device according to either claim 1 or claim 2, characterised in that the sensor (50, 52) is designed as a temperature sensor arranged inside the housing casing (11) and/or in an air removal channel (39a-c).
4. Drying device according to any of claims 1 to 3, characterised in that the inner drum (1) is made up of two half shells (2, 3) which each extend over approximately half of the drum circumference, the inner space of each half shell (2, 3) being divided by at least one partition wall (21-24), which is fixed in position relative to the half shell (2, 3), into at least two compartments (12-17) which are axially one behind the other in relation to the inner drum (1) in such a way that when the two half shells (2, 3) are opposite one another so as to be in alignment, the respectively opposite compartments (12, 15; 13, 16; 14, 17) together form a closed inner drum chamber (18-20).
5. Drying device according to claim 4, characterised in that a half shell (2) is axially displaceable relative to the other half shell (3) in order to convey a batch of laundry (25) out of an inner drum chamber (18, 19) into the next inner drum chamber (19, 20) in a laundry conveying direction (26).
6. Drying device according to any of claims 1 to 5, characterised in that the inner drum chambers (18-20) are connected, in terms of airflow, one behind the other, counter to the laundry conveying direction (26), by means of the air duct (34) such that the chamber airflows (L1-L3) are part of a counter airflow (L) which first flows through the last inner drum chamber (20) in the laundry conveying direction (26) and lastly flows through the first inner drum chamber (18) in the laundry conveying direction (26).
7. Drying device according to any of claims 1 to 6, characterised in that the air removal channel (39a-c) assigned to each inner drum chamber (18-20) is connected to the corresponding air supply channel (38a-c) by means of a circulation channel (43a-c) for returning drying air.
8. Method for operating a drying device for laundry according to any of claims 1 to 7, in which a batch of laundry (25) to be dried is exposed to a drying airflow (L) in an inner drum chamber (19) formed as a drying chamber (19) in order to remove the moisture from said laundry, the residual moisture of the batch of laundry (25) being continuously ascertained and compared with a target value, the result of the comparison being used to control the heating of the drying airflow (L) and/or the duration of the drying process, it only being possible to convey the batch of laundry (25) out of the drying chamber (19) after the residual moisture of the batch of laundry ascertained is lower than the target value.
9. Method according to claim 8, characterised in that the residual moisture of the batch of laundry (25) to be dried is ascertained on the basis of the air moisture and/or the temperature of the drying air removed from the batch of laundry (25).
10. Method according to claim 9, characterised in that the residual moisture of the batch of laundry (25) is ascertained by comparing the air moisture and/or temperature of the drying air removed from the batch of laundry (25) with the air moisture and temperature, respectively, of the drying air supplied to the batch of laundry.
11. Method according to any of claims 8 to 10, characterised by the following processes for a batch of laundry (25) which are carried out one after the other: a heating process, in which the batch of laundry (25) is heated by passing heated drying air therethrough, a drying process, in which the batch of laundry (25) is dried by passing heated drying air therethrough, and a cooling process, in which the batch of laundry (25) is cooled to below a threshold temperature by passing cold drying air therethrough.
12. Method according to claim 11, characterised in that the heating process, the drying process and the cooling process are carried out on a plurality of batches of laundry (25) both at the same time and spatially separately from one another in a heating chamber (18), a drying chamber (19) and a cooling chamber (20), respectively, and in that a process cycle common to all processes is followed in each case by a conveying phase, in which the batch of laundry (25) is conveyed to the next chamber (19, 20) in the laundry conveying direction (26).
13. Method according to claim 12, characterised in that heating of the chamber airflow (L2) flowing through the drying chamber (19) is stopped as soon as the residual moisture of the batch of laundry (25) in the drying chamber (19) falls below the target value.
14. Method according to claim 12, characterised in that heating of the chamber airflow (L2) flowing through the drying chamber (19) is controlled such that the residual moisture of the batch of laundry (25) received in the drying chamber (19) reaches the target value at approximately the time at which the temperature of the batch of laundry (25) received in the cooling chamber (20) reaches the threshold temperature.
15. Method according to any of claims 12 to 14, characterised in that the process cycle is finished as soon as the residual moisture of the batch of laundry (25) received in the drying chamber (19) has reached or fallen below the target value, and the temperature of the batch of laundry (25) received in the cooling chamber (20) has reached or fallen below the threshold temperature.

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