The present invention relates to a textiles treatment apparatus, in particular to a dryer, a refreshment apparatus or a washing machine having refreshment function, adapted to determine a textiles-related or programming parameter. The invention also relates to a method for determining a textiles-related or programming parameter.
EP 1 441 060 A1
discloses a tumble dryer having one or two injection units arranged in proximity of the loading door of the dryer to inject an additive like water steam, a cleaning detergent, a fragrance or a disinfectant into the drum. It is proposed to reduce, stop or reverse the air flow through the drum to optimize the efficiency of the injected additive. The amount of additive to be supplied into the drum via the injection units is set by means of a dosing unit.
It is an object of the invention to provide a method and a textiles treatment apparatus which are adapted to determine at least one textile-related or programming parameter in a convenient and cost-effective manner. Also a method is provided using a textiles-related and/or programming parameter determined in such a manner.
The invention is defined in claims 1, 19 and 23, respectively.
Particular embodiments are set out in the dependent claims.
According to the method of claim 1, at least one textile-related parameter in a textiles treatment apparatus is detected. Preferably, the textiles treatment apparatus is a dryer, a refreshment apparatus or a washing machine having a drying function. The textiles treatment apparatus has a storing compartment for storing textiles to be treated, for example a rotatable drum used in a tumble dryer or in a washing machine. Further, at least one additive supplying device is provided, which is used to directly or indirectly supply an additive to the storing compartment to be applied to the textiles stored therein. Preferably, at least one additive supplying device supplies the additive in form of steam into the storing compartment (see claim 29), and additionally or alternatively the additive is water only or water comprising another additive. While it is preferred to supply the additive in steam phase to the textiles, the at least one additive can also be supplied as aerosol or fog. The additive is not supplied in liquid form onto the textiles, e.g. not in form of a liquid flow or droplets which are larger than droplets convenient to form an aerosol. The term 'textiles' used herein includes any type of laundry or any type of fabrics.
For determining the at least one textile-related parameter at least one additive from the at least one additive supplying device is supplied into the storing compartment, and the at least one supplied additive interacts there with the textiles stored therein. A response of the textiles due to the interaction with the at least one supplied additive is detected or monitored. A response of the textiles is a detection signal detected with a sensor or detector of the textiles treatment apparatus. The response signal may for example be a periodical detection signal, a single detection signal, a continuous detection signal, a preprocessed detection signal (for example an averaged signal), a group of signals, a time averaged signal, or the like.
The detected response is used in a determining step, in which the at least one textile-related parameter is determined by processing the at least one detected response. Preferably, the textile-related parameter derived or determined from the response is not the same type of parameter as the response itself, i.e., if for example the textiles humidity and/or temperature is detected as a response, then the textile-related parameter is not the temperature and/or humidity of the textiles.
In claim 1, alternatively or additionally to determining the at least one textile-related parameter, a programming parameter for a subsequent textiles-treatment program is determined in the same way as the at least one textile-related parameter is determined. If, for example, the determining method is used to adapt a textiles-treatment program running subsequent to the determining method or including the determining method in the starting phase, a programming parameter for adapting is determined, which itself depends on a textiles characteristic (i.e. a textiles-related parameter). This means that not in any case it is necessary to determine the textile-related parameter by the determining step, and then to derive from the textile-related parameter the programming parameter. Instead, the programming parameter can be determined by the determining method directly without the detour over the textile-related parameter. However, in other cases it is preferred to determine the textile-related parameter, as the textiles treatment program may require the adaptation of several program parameters which are used in one or different subsequences of the textiles-treatment program and which can easier be derived from the textile-related parameter - instead of deriving all programming parameters from the detected textiles response.
By determining at least one textile-related parameter and/or programming parameter with such a determining method it is not necessary to provide additional sensors or detectors and/or to request additional inputs by a user of the textiles treatment apparatus to determine textile-related parameters or programming parameters to be used for treating the textiles. For example, it is not necessary to provide a weight detector to detect the weight or amount of laundry to be treated, and it is also not necessary to request a type of textiles from the user when starting the textiles treatment program. In particular, when the at least one additive supplying device is required for additive supply during the textiles treatment program, its use during the determining step does not increase manufacturing costs for the apparatus. Also, it is possible to provide a 'universal' program, which the user has only to start and in which the textile-related parameters or programming parameters are detected automatically using the determining method. Further, the universal program adapts itself and avoids damage to the textiles (for example delicate textiles like wool) and the consumption of resources (additive consumption/energy consumption) is self-optimizing. Both result in an optimized treatment result for the textiles to be treated.
According to a preferred embodiment, the detected response signal(s) of the textiles also include(s) or is (are) (a) time response(s), for example a variation in time or a time characteristic. The time response broadens the information basis and enables to derive more parameters or more reliable parameters in view of the textiles properties.
In a preferred embodiment the detected response is a temperature and/or a humidity related to the textiles reaction onto the supply of the at least one additive. Most preferably, the textile humidity is detected, in particular its time dependency, as the textiles humidity response represents a very sensitive indicator for the textiles characteristic (i.e. textile-related parameter). In other embodiments the air temperature or the air humidity are detected, which implicitly also depend on the textiles humidity. In another embodiment the certainty of determining the at least one textile-related parameter is improved in that at least two different response signals are detected of the textile's reaction to the additive supply. For example, the air temperature and the textiles humidity can be combined in the determining step to increase the reliability in determining the at least one textile-related parameter.
According to a preferred embodiment, the textiles response onto the additive supply is detected during and/or after the additive supply. As mentioned above, the detection 'during' and/or 'after' comprises one or more of: detection of a unique response signal, an intermittent or a periodical detection, a detection at predefined time points, a continuous detection, an average detection, an integrated detection and the like. For example, the additive absorption behavior of the textiles during the supplying step and/or subsequent to the supplying step is monitored.
To improve the reproducibility for determining the at least one textile-related parameter or the at least one programming parameter, it is preferred that during the supplying step the additive is supplied using a predefined additive (e.g. steam) flow rate and/or additive (e.g. steam) temperature. This includes for example a predefined additive flow rate variation over time, wherein for example the additive flow rate at the beginning of the supply step is higher than at the end of the supply step, thereby increasing the resolution of the detected textiles response.
Preferably, the at least one textile-related parameter is the amount of textiles and/or the type of textiles. For example in a textiles treatment program, the drying temperature or the temperature of an additive to be supplied to the textiles is very critical for an optimum treatment result and for avoiding damages to the textiles. On the other hand, the consumption of resources for the textile treatment depends on the amount of textiles stored in the treatment compartment, such that by determining this parameter the processing times or the amount of additives to be supplied during the textiles treatment program may be adapted in dependency of the amount of textiles. Alternatively or additionally, a surface condition of the textile is determined, for example an additive absorption rate determined by the absorption of the additive supplied into the storing compartment at the surface of the textiles. If, for example, the absorption efficiency is high, additive supply sequences during the subsequent textiles treatment program can be programmed, such that high supply rates of the additives are used during a short time, whereas, when the absorptivity is low, the subsequent treatment program is adapted such that the additive is supplied at a lower flow rate for a longer supplying period.
In a preferred embodiment the detection result is compared to representative or exemplary detection responses stored for example in a look-up table and the coincidence or similarity between the detected response and the reference responses is determined. From the best match, the prestored at least one textile-related parameter and/or the at least one programming parameter is derived. This provides a simple implementation to derive the required parameters from previous reference response behaviors of textiles having known textile-related parameters or for which specific programming parameters are required in the subsequent treatment program. Additionally or alternatively, a semi-empirical modeling is made and a fuzzy-logic or a neural network is correspondingly programmed to assign specific parameters to specific classes of detected responses.
By repeating the supplying step and the detection step at least two times, the predictability or accuracy when determining the at least one parameter (textile-related or programming) is increased. For example, the detection accuracy is improved by averaging the detection results of several supplying steps and/or intermediate phases between the supplying steps and/or the change of the response signal from one supplying step to another supplying step or from one intermediate step to another intermediate step.
This can also be used to determine additional parameters.
For improving the repeatability of the response signal and thereby the determining of the parameter, the starting conditions for the determining method are normalized prior to starting the first and/or the subsequent supplying steps. For example, prior to the first supplying step the textiles stored in the storing compartment are dried to a predefined (starting) humidity level or range.
Preferably, the supply of the at least one additive is continued until a predefined humidity level or range of the textiles and/or the air is achieved. For example, a low textiles humidity is set as the predefined level or threshold, such that the subsequent textile treatment program can be started at a low textiles humidity. Also, the supply time is short, when the predetermined textiles humidity level or range is selected in the lower range. In a preferred embodiment, after the additive supply sequence, it is an additive absorption sequence in which the textiles absorb the additive previously supplied during the supply sequence to detect the response of the textile, and at least a portion of the response is used to determine the at least one textiles-related and/or programming parameter. In this absorption phase the humidity detection signal is not interfered by the humidity introduced by the additive supply.
In preferred embodiments the increase time or increase behavior of increasing the humidity or temperature during an additive supply sequence between two temperature and/or humidity levels or ranges is detected at least once, and the increase time and/or increase behavior is processed for determining the at least one parameter. Alternatively or additionally, a decrease time or decrease behavior is monitored or detected subsequent to a supply sequence, and the characteristic of the decrease time or decrease behavior is used to determine the at least one parameter. For example, such an increase/decrease time or increase/decrease behavior is used to determine the type of textiles. In an alternative embodiment or additionally a number of cycles including steam supply phases required to reach a predetermined medium humidity and/or cycles run through within a given time period is counted and also used to determine the at least one parameter. For example, the number of cycles is a measure for the amount of laundry loaded into the storing compartment.
Preferably, the temperature and/or humidity of the textiles or the air is detected, for example of the air in the storing compartment or of the air ventilated through the storing compartment. Then this time response is processed in the determining step, wherein a time response enables a much more sophisticated analysis of the response of the textiles due to the interaction with the supplied additive. The characteristic of a curve over the time is an indication for the type of textiles due to the fact that different types of textiles have different properties in relation to the interaction with the supplied additive. For example, as compared to jeans material, toweling textiles have a much larger surface area exposed to the additive supplied into the storing compartment. Therefore, although the toweling laundry may have the same weight as jeans laundry, the absorption rate for toweling is much higher than for jeans laundry. As another example, textiles made from synthetic yarn or textile yarn, which for example may be impregnated for being waterproof, have a much lower absorptivity than a cotton yarn composed of lots of strands. Therefore, the time response of a detected response signal is convenient to differentiate between different types of textiles. It is also convenient to detect different surface properties of the textiles, for example previously impregnated textiles, previously dried textiles or previously washed textiles.
According to a further embodiment, the textiles and/or air humidity is detected using at least two humidity detectors. Preferably, two humidity detectors are used, which detect different humidity states of the textiles. The at least two humidity detectors can be located at different locations in the textiles storing compartment or may have different spacings between their detector surfaces (conductivity measurement). Or one detector is operated in different modes, such that different states of the textiles humidity are detected. For example, input signals of different frequency or voltage are applied to the detector's detection surface, such that the different sensitivities are indicative for different humidity states or include different signal portions of the two humidity states.
Thereby, using the different signal responses of the at least two humidity detectors or the one humidity detector operating in different modes, a differential processing is performed, where the differences between the two signals are included in the signal analysis, and results in more information related to the textile-related parameter. For example the textile type may be derived from the differences in the two signals. Differences in the signals may for example result in that the one humidity detector detects the air humidity, one detector essentially detects the surface humidity of the textiles and/or one detector detects the core humidity of the textiles.
According to claim 19, a method of operating a textiles treatment apparatus is provided, in which first at least one textile-related parameter and/or at least one programming parameter is detected, and then a textiles treatment program sequence is adapted and/or selected (automatically) in dependency of the at least one detected textile-related parameter. The steps of detecting at least one textile-related parameter may form a portion of a textiles treatment program, i.e. the textiles treatment program includes the detection step and the textiles treatment program sequence. As already mentioned above, the user comfort is improved thereby in that the number of user input requests can be reduced or the user input requests (selection of program options or programs) can be completely avoided. Additionally or alternatively, mechanical or electrical components of a textiles treatment apparatus may be reduced (for example user selection buttons for user information display can be reduced or avoided) or other sensors being normally necessary to determine a textile-related parameter can be omitted (for example weight sensor).
In particular, where the textiles treatment apparatus comprises at least one additive supplying device used then in the textiles treatment program sequence, a double function or use of the at least one additive supplying device results in that it is used for the detecting step and also during the textiles treatment program sequence.
The textile treatment apparatus according to claim 23 comprises at least one additive supplying device adapted to supply at least one additive, a textiles storage compartment and a control unit. The control unit is adapted to control the operation of the textiles treatment apparatus, and thereby to control the operation of the at least one additive supplying device and the detection unit. During and/or after at least one steam supplying sequence controlled by the control unit, at least one response signal is provided from the detection unit to the control unit to be processed by the control unit and to retrieve at least one textile-related parameter and/or programming parameter. Advantages achieved thereby have already been discussed above and the embodiments related to the detection method or method of operation of a textiles treatment apparatus are fully applicable for the textiles treatment apparatus under the control of the control unit. Therefore, reference is made in full extent to the above and embodiments are also applicable here. On the other hand, embodiments of the apparatus are fully applicable to the methods.
Reference is made in detail to preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings, which show:
- Fig. 1
- a table showing an assignment of textile types and load in dependency of detected durations and cycle numbers,
- Fig. 2
- a typical humidity behavior over time during intermittent steam supply,
- Fig. 3
- a flow chart for detecting durations and cycle numbers,
- Fig. 4
- a schematic block diagram of functional elements of a refreshment dryer, and
- Fig. 5
- time responses of the humidity detected by different sensors or for different textile types.
Fig. 4 schematically shows some functional elements of a tumble dryer 2. In the dryer 2 the laundry to be treated or dried is stored in a drum (not shown) driven by a motor 4. Rotational speed and rotation direction of the motor 4 can be controlled by a control unit 30 (CPU). A fan arranged in an inlet channel is driven by a second motor 5. When operating in condenser mode, the air ventilated through the drum is passed through a condenser from where the circulated air is further guided through a heater 6 before being reintroduced into the drum. The humidity of the laundry in the drum is detected by a humidity sensor 8 formed as a conductivity sensor. The conductivity sensor detects the electrical conductivity of the laundry between two metallic contacts at the drum's inside which are spaced from each other. In alternate embodiments or in addition to the conductivity sensor 8 the air humidity of the air flown through the drum can be detected at another position in the air passage, for example at a location close to or at a fluff filter at the loading door of the drum. Further, a second temperature sensor 20 is arranged at the loading opening of the drum to detect the temperature of the air within the drum.
An additive injector 10 generates water steam supplied via a supply line into the drum's inside. Under the control of the control unit 30, a pump 12 assigned to the additive injector 10 pumps water from a water reservoir (not shown) into the additive injector 10, in which a heating element 16 is arranged to evaporate the water. The power dissipated by heating element 16 is also controlled by control unit 30, such that steam flow rate and/or steam temperature are controlled by correspondingly setting the temperature within the additive injector 10 by heating the heating element 16 and by pumping a controllable flow of water into the additive injector 10 where the water is brought into contact with the heating element 16. The temperature within the additive injector 10 is detected close to the heating element 16 by a first temperature sensor 14.
In an embodiment not shown, the steam temperature is detected with an additional temperature sensor within the steam supply pipe, or the temperature signal of the sensor 20 adjacent to the injection point of the steam into the drum is taken as the steam temperature during steam supply phases (while it is e.g. taken as an air temperature signal in non-steam supply phases). The steam temperature signal thus detected is also supplied to the control unit 30 and processed there to adjust the steam temperature either by taking this signal exclusively to control operation of the heating element 16 and thereby the steam temperature, or it is taken as a correction signal together with the temperature signal from the first temperature sensor 14 to control the operation of heating element 16.
The control unit 30 is connected to an input panel 40 including a display section 42. The user inputs program selections via the input panel 40 and input options or the processing state of the dryer is indicated to the user by the display section 42. As mentioned below, the input requirement for the user is simplified here by automatically determining the laundry's humidity, the type of laundry and the laundry's load. So, the user selection can be simplified to the user inputs 'Start'/'Stop', 'Drying'/'Refreshing'/'Dry cleaning', 'Iron aid On/Off', and 'Anti-crease On/Off'. The control unit 30 further includes a sub-unit 32 receiving or sending signals to the heating element 16, the pump 12 and the first temperature sensor 14 of the additive injector 10 to control flow and temperature of the steam supplied to the drum. Further, the signals of the humidity sensor 8 and the second temperature sensor 20 are processed during drying sequences, to control and optimize the drying progress by correspondingly adjusting the heating of heater 6, the air flow induced by the fan (motor 5) and the agitation of the laundry via the drum rotation (drum motor 4). Further, the detected signals of sensors 8 and 10 are preprocessed by the sub-unit 32 (e.g. averaged and normalized) and fed to a look-up-memory 34 to retrieve laundry-related parameters (here load and type) and programming parameters by comparing a set of detected signals to a set of reference signals - compare for example the table of Fig. 1 and the explanations below.
The tumble dryer 2 is designed to execute fabrics treating programs like cloth refreshment, anti-crease treatment, dry cleaning, drying, disinfection, impregnation etc. In some or all of these programs the power or resources consumption and the treatment result can be optimized, when at least some information about the laundry to be treated is available. For example, information about the starting humidity of the laundry (which may be completely dry, when performing a chemical cleaning, or which can be wet after loading the laundry from a previous washing procedure), information about the laundry's weight (which can be used as a measure for additive amounts to be supplied, for the heating energy or for the durations during subsequences of the treatment program) or information about the type of the laundry (synthetics, cotton, wool, functional textiles), which can be used to optimize the treatment temperature, the temperature of additives to be supplied or the durations of specific subroutines. The information about the laundry is also used for example to adapt a subsequent treatment program, for example in that subsequences specifically optimized for the laundry properties are added, or in that subsequences being not convenient for the textiles properties are skipped. If, for example, laundry properties can be automatically derived in a detection procedure, a 'universal' program can be implemented, which automatically adapts all processing parameters in dependency of the detected laundry properties or characteristics. An example of such a detection procedure is described in the following, which determines the laundry's weight (or volume) and the type of the laundry as the most relevant parameters for the fabrics processing.
Fig. 2 shows a humidity response behavior over time in reaction to three steam supply sequences. Curve S is the surface humidity of the laundry stored in the drum which is rotated during the steam supply sequences as well as during the absorption sequences. With completely dry laundry loaded into the drum, at time t = 0 control unit 30 activates the additive injector 10 to supply steam into the drum, which results in an increase in the laundry's surface humidity S detected by humidity sensor 8.
From the starting time t = 0 steam is supplied as long as the first time a maximum humidity threshold Hmax is reached at time t1a. At the threshold Hmax, the steam supply is stopped and the laundry in the drum soaks the excessive air humidity, and also the surface humidity S is transformed into a core humidity C (compare Fig. 5). The first soaking or absorption sequence is from time t1a to time t1b,
wherein at time t1b the detected humidity reaches a lower humidity threshold Hmin. When the lower threshold Hmin is reached at t1b, the steam supply via the additive injector 10 is started again and the surface humidity S rises from the lower threshold Hmin to the upper threshold Hmax where the steam supply is stopped again at time t2a. From t2a to t2b the laundry again absorbs the humidity, and the surface humidity drops from Hmax to Hmin, whereupon from time t2b the steam supply is started again until at time t3 the upper threshold Hmax is reached again. From t3a the steam supply is stopped again.
The detected humidity signal S is then processed to determine the laundry type and the laundry load. In the exemplary embodiment the time periods t1 and t2 required to settle the surface humidity from Hmax to Hmin are determined by t1=t1b-t1a and t2=t2b-t2a. On.the other hand, the number of steam generation/absorption cycles (number of cycles from starting the supply from Hmax to reaching the lower threshold Hmin after Hmax has been passed) determines the laundry load. In Fig. 2 two such steam generation/absorption cycles are run through, before after t3 the humidity of the laundry does not reach the lower threshold Hmin again due to saturation of the laundry with humidity. In other embodiments it can be provided that a maximum time period from time t = 0 is given, for example five minutes, three minutes or preferably two minutes, and the number of cycles run through in this time period are counted.
As shown in Fig. 1, the time periods t1, t2 to reach the minimum humidity threshold Hmin are taken as a measure for the type of textiles, here shown as a discrimination between cotton-type textiles and synthetic-type textiles. The number of steam generation/absorption cycles is taken as a measure for the load (weight or volume) of the textiles in the drum. This means that by analyzing a time response of the surface humidity S as shown for example in Fig. 2, two characteristics are derived from such a curve and applied to a comparison scheme (Fig. 1) to determine the type of textiles and the respective load.
Instead of starting steam supply at time t = 0 with laundry humidity = 0%, steam supply could also be started with a laundry humidity being preferably lower than Hmin. If, for example, wet laundry is loaded into the drum (from a previous wash program), then the laundry can be dried in the dryer until the starting humidity at t = 0 is lower than Hmin, at least lower than Hmax. Alternatively, if the starting humidity of the laundry is not too high, the threshold humidities Hmax and Hmin can be shifted, such that at least the maximum humidity Hmax is higher than the starting humidity of the laundry. Of course, such a shifting of the thresholds Hmin, Hmax is only acceptable to a predetermined threshold, for example a starting humidity of the laundry being lower than 50%, preferably lower than 30%, more preferably lower than 20%. Otherwise, if the starting humidity is higher, the laundry is dried to an acceptable starting humidity level as mentioned above.
Fig. 3 shows another embodiment of a flow diagram implementing a determining procedure basically adapted to the processing described in connection with the analysis of the time response shown in Fig. 2. At step S1 the determining subroutine is started with drying the laundry loaded into the drum. In this initial phase the humidity detection is also started, which normally requires some time averaging before a reliable humidity detection value results. In step S3 it is determined whether the laundry has a humidity below a predetermined starting humidity. If not, the drying process is continued. Otherwise, if the laundry humidity is below a predetermined starting humidity, in step S5 the drying subsequence is stopped, and at the same time the steam generation and steam supply by the additive injector 10 is started. During the steam supply subsequence the drum movement is continued. Generally, during the steam supply sequences and the following absorption sequences the drum movement may be a constant rotation speed or may be in a reversing mode in which the drum rotation direction is reversed several times. Preferably during the steam supply and the absorption sequences the fan is stopped, i.e. no air is ventilated through the drum. In step S7 it is checked whether a predefined upper humidity threshold (for example Hmax) is reached. If not, the loop S5, S7 is repeated until the predefined upper humidity threshold is reached and the procedure continues with step S9. In step S9 the steam generation and therefore the steam supply is stopped, the drum continues its movement and a counter is started. In step S11 the drum movement is continued and the laundry humidity is monitored until a predefined lower humidity threshold (for example Hmin) is reached. As soon as the lower humidity threshold is reached, the procedure continues in step S13 where the counter is stopped and the time period between starting and stopping the counter is determined. If this steam supply (S5) and absorption (S9) cycle is executed the first time, a first time period (compare t1 in Fig. 2) is stored, when this steam supply/absorption cycle is run through a second time, a second time period is stored (t2), etc.
If in step S11 the lower humidity threshold (e.g. Hmin in Fig. 2) is not reached or not reached within a predefined time period since starting the counter or since starting from step S1, the steam supply/absorption cycles are terminated and in step S15 the number of steam generation/absorption cycles since the start of the determining procedure (S1) is calculated. For example, a second counter counts the number of times, when the procedure passes the program flow from step S13 to step S5. As mentioned above, using the calculated time periods (step S13), the type of laundry is determined in step S19. And by using the number of steam generation/absorption cycles in step S17, the amount of the laundry is determined. Thereby, the determining subroutine comprising the steps S1 to S19 is finished and a program including at least one steam supplying step for treating the laundry in the drum is executed then.
In dependency of the determining steps S17 and S19 the program branches to one of steps S21, S23 or S25, wherein in step S21 a short time steam treatment is performed for a minimum laundry load, in step S23 a medium-time steam treatment is performed for a medium laundry load, and in step S25 a long-time steam treatment is performed for a high or maximum laundry load. At the same time and in dependency of the textile type the temperature maintained during the steam treatment processes in steps S21 to S25 is adapted in dependency of the textile type. For example, synthetic-type laundry is treated at a lower air temperature and lower steam temperature, while cotton-type textiles are treated with a higher air temperature and a higher steam temperature. Thereby, an optimized treatment program is performed, in which under optimizing the resources an optimized treatment result is achieved, thereby avoiding damage of the laundry.
Fig. 5 shows a time diagram for humidity responses of steam supply cycles (steam supply ON) and absorption phases (steam supply OFF). Different humidity responses are shown in a schematic way, wherein the humidities are not shown to scale, but only in a relative representation. Curve A represents an air humidity response which is for example detected by an air humidity detector arranged at the loading door of the drum or in an air channel (not implemented in the exemplary methods described above). Curve A represents the humidity when starting the first time the steam supply with laundry having zero humidity. This means that the air humidity before the first steam supply is zero or almost zero. As soon as the first steam supply is started, the increase of the humidity A is very steep and has an asymptotic approach to 100% air humidity. In the absence of any laundry in the drum the air humidity A would almost step-like jump the first time from 0% to 100% humidity after the steam supply. In the presence of dry laundry the increase is asymptotic due to the humidity absorption from the air to the surface of the laundry. After stopping the steam supply, the air humidity only slowly drops, and drops also only to a relatively high humidity level (90% shown here), as the equilibrium between absorption of air humidity at the laundry and the evaporation of humidity from the laundry results in a higher air humidity despite lower laundry humidity values. So, even in the absorption phases (steam supply OFF), the air humidity A remains high. A comparison of the first absorption phase and the second absorption phase shows that with increasing the total humidity or the core humidity C of the laundry the minimum humidity level reached during the absorption phases increases with the increase of the laundry's core humidity, i.e. in the second absorption phase the lowest air humidity value is higher than the lowest air humidity value during the first absorption phase.
Curve S1 depicts the surface humidity of the laundry, which is typically measured in a drum by using conductivity measurement over electrodes arranged in the drum. The surface humidity increases slower than the air humidity and to much lower humidity levels, which is here the predefined upper humidity threshold Hmax at which the steam supply is stopped. The upper threshold Hmax is set here to 12% surface humidity. S1 is a time response for laundry having a low surface absorptivity, which means that the air humidity is slowly absorbed. For example, the curve is representative for synthetic yarn or for textiles having an impregnated surface. Compared thereto, Fig. 5 shows a second surface humidity response S2 being representative for towel textiles having a high surface area in relation to the laundry weight, such that a high absorptivity for air humidity results. It is to be noted that the time scale for the surface humidity S2 is compressed as compared to the time scale of the surface humidity S1, since due to the high absorption of this type of textiles the upper surface humidity threshold Hmax is reached at a later time. However, for illustrative purposes, the surface humidity response S2 being representative for example for towels is normalized to the time scale of the surface humidity response S1 (where curves A and C relate to response S1). As soon as the steam supply is stopped, a steep decrease in the humidity response S2 results due to the rapid absorption of air humidity by this type of laundry. Correspondingly, the air humidity curve A would be different for this type of textiles as compared to the depicted air humidity response A, and also the core humidity C of the textiles is different in this case. As can be seen by comparing the characteristics of surface humidities S1 and S2, a type of textiles can also be determined using these different characteristics during the processing for determining the type of laundry.
- Reference Numerals List
As mentioned above, curve C shows the core humidity of the laundry, which is normally not detected and which means a humidity value in the center or core of the laundry, i.e. these areas of the yarn or textile parts, which are not directly exposed to the surrounding air. As shown, the core or average humidity of the laundry steadily increases over the time during the steam supply and absorption phases,
wherein the increase during the steam supply sequences is much higher than during the absorption sequences. During the absorption sequences the air humidity and predominantly the surface humidity penetrates into the core or center of the laundry and also contributes to an increase of the core humidity.
- tumble dryer
- drum motor
- fan motor
- humidity sensor
- additive injector
- first temperature sensor
- heating element
- second temperature sensor
- control unit (CPU)
- look-up memory
- input panel
- display section
- air humidity
- core humidity
- S, S1, S2
- surface humidity