EP1921202A2 - Method for determining the load in a washer-drier and washer-drier - Google Patents

Abstract

The method involves establishing a maximum value over time of absolute atmospheric humidity in an air outlet (20) during operation of a spin or tumble dryer (11), and determining laundry load (14) quantity in a loading chamber (12) using the maximum value. Reference values for correlating the maximum value of the absolute atmospheric humidity with a specific load quantity are stored in a memory for a comparison. The laundry load in the loading chamber is determined by comparing the maximum value of the absolute atmospheric humidity with the reference values. An independent claim is also included for a spin or tumble dryer comprising a laundry chamber for containing a laundry load of a certain quantity for drying.

Description

The invention relates to a method for determining the amount of charge of laundry in a tumble dryer and a correspondingly constructed tumble dryer.

There are various ways known how the amount of charge can be determined in a tumble dryer. From the EP 1 067 233 B1 For example, it is known to determine an imbalance during spin and to draw conclusions about the amount of charge.

From the EP 1 295 979 B1 It is known to measure the electrical resistance or conductance of the laundry in the tumble dryer. Also from this can be in connection with the elapsed time, the amount of charge determine. However, since the laundry in the tumble dryer is always shaken up, the measurements are inaccurate.

From the DE 42 43 594 C2 It is known to use both humidity sensors and temperature sensors. The charge quantity can also be determined from their measurement results. The component cost is considerable.

Task and solution

The invention has for its object to provide an aforementioned method and a corresponding dryer, with which disadvantages of the prior art can be avoided and in particular with limited effort, the amount of charge can be determined in laundry in a tumble dryer.

This object is achieved by a method having the features of claim 1, 3 and 6 and by a corresponding tumble dryer with the features of claim 12. Advantageous and preferred embodiments of the invention are the subject of further claims and are explained in more detail below. Some of the features are described only once. However, they should apply regardless of both the process and for the appropriately trained tumble dryer. The wording of the claims is incorporated herein by express reference.

The absolute humidity is measured in the air outlet, which leads away from the hold of the tumble dryer. Particularly advantageous is the application of the invention to exhaust air dryers which blow the moist air into the outside environment, but it is not limited thereto. According to the invention, in a first fundamental

Embodiment of the invention determines the amount of charge in the cargo space characterized in that the maximum value and / or the course of absolute humidity in the air outlet or in the air discharged from the hold of the tumble dryer is determined. For this purpose, so to speak, the measured values are repeatedly determined, and as soon as they fall again after an initial increase, the maximum value is just exceeded. For this purpose, usually a single humidity sensor is sufficient, which keeps the expenditure on components as well as on installation time within limits.

It is exploited that there is a relationship between the absolute humidity and the amount of water present in the laundry. This amount of water in turn is, in particular at known residual moisture after the washing process, depending on the amount of laundry, and thus can be concluded from the absolute humidity on the amount of laundry. Under certain circumstances, this can still be influenced by the type of laundry or the fabric. For this purpose, however, information can be obtained either from the type of the selected drying program, which can be recognized as a rule, for example, whether cotton laundry should be dried. Furthermore, as will be explained below, an attempt can also be made to determine this residual moisture more accurately.

In the method with determination of the maximum value of the absolute humidity, the individual values are compared with each other and of which the highest or the maximum value is used. This collection of values may be within a certain time window. Alternatively, it can be assumed that the maximum value has been detected if no further higher value has been detected for a certain time after the highest value so far, for example a few minutes.

The detection is slightly different if the course of the absolute humidity is monitored. Then, measured values are not compared with each other in terms of their absolute value, but they are compared relative to each other. If the vast majority of successive absolute humidity readings are above the previous one, the curve will increase. If the vast majority of measured values lie below the preceding one, the curve will drop. If a time window of a few minutes is selected for each of these, then the observation of the gradient of the course of the absolute air humidity can also be concluded approximately to the maximum.

The course of absolute humidity is usually such that it rises sharply after being loaded with wet laundry and starting to operate. Then it falls or flattens and reaches a rather shallow maximum to fall off relatively flat from there on. The more wet laundry in the cargo hold, the higher the maximum value of the course, and the flatter it falls off. The differences of the maximum values as a function of the charge quantity are so great that they allow a determination of the charge quantity on the basis of the maximum value of different charges dependent on the charge quantity.

The advantage of determining the charge amount of laundry present in the load compartment is that automatic program sequences can be optimized or better adapted to the actual amount of charge present. This is mainly due to the fact that the moisture content of laundry after a washing process is usually in a relatively narrow range, that is about always the same, in particular a residual moisture content of about 50% to 70%, ie the weight of water contained based on the weight of Laundry. If the charge quantity is known, all the moisture in the cargo space can be determined and a program sequence can be tuned to it be, especially in terms of duration, intensity of heating, etc ..

Advantageously, it is possible for values to be stored for a correlation of maximum values of the absolute air humidity with a specific charge quantity. This means that in the case of a residual moisture of the laundry which has been assumed to exist, a relationship is stored between the maximum value of the absolute humidity and the given amount of charge, in particular for a particular type of tumble dryer. By comparison in a control of the tumble dryer, the charge amount of laundry present in the hold can then be determined from the maximum value of the absolute humidity determined by measurement.

In an alternative basic embodiment of the invention, the amount of charge in the hold is determined according to the invention by determining a value of the absolute humidity in the air outlet of the hold at a certain defined time after the start of operation of the tumble dryer. Here, it is advantageously provided that values for the absolute air humidity are stored at a particular point in time in correlation with a specific charge amount of laundry in the tumble dryer. In a control of the tumble dryer, in turn, a comparison can be made of the measured absolute humidity at a certain time and with these stored values. From this, the amount of charge in the hold can then be determined again. For this as well as for the aforementioned possibility of comparing maximum values of the absolute humidity with a charge amount in the cargo space, the respective values can be experimentally determined for a specific type of clothes dryer, and then stored in a controller. The aforementioned specific time may advantageously be between 5 minutes and 40 minutes after the start of operation. It is advantageously taken into account that in the first 5 minutes, the value of the absolute humidity still increases so much that this behavior is essentially independent of the amount of charge. Only after an even longer time, the gradients change depending on the amount of charge. Advantageously, the specific time is about 15 to 20 minutes. In many cases, this time is after reaching the maximum value, when the course is already falling again.

According to yet another alternative basic embodiment of the invention, the time at which the gradient of the absolute air humidity, that is to say the gradient of its curve, assumes a specific value is used to determine the charge quantity. Again, values for a correlation of different values of the gradient at specific times with a certain amount of charge dependent thereon are advantageously stored. Control of the clothes dryer, in turn, performs the comparison between the measured and recorded absolute humidity gradient and the time. From this, it is then possible to determine, as before, the amount of charge of wet laundry in the hold.

Particularly advantageous for the aforementioned embodiment of the method of the time is used, to which the gradient of the absolute humidity is already negative again, ie after reaching the maximum value. The advantage with this method is that a longer time is required, for example 20 to 30 minutes. In this time range, the above-mentioned profiles for the absolute humidity differ depending on the time depending on the amount of charge from each other. Even so, a distinction can be made. It is also possible to use the time when the Gradient of absolute humidity has become zero. In particular, it may be a point in time at which the gradient thereof decreases again or decreases and is negative.

It can be advantageously provided that the duration of a plateau-like course of the absolute humidity is determined and from this the residual moisture is determined, which had the laundry after washing and before the drying process. The longer the duration of the plateau phase, the higher the residual moisture is assumed. Knowing this residual moisture, so you can determine the expected end of the drying process even more accurate. The plateau phase can be defined in such a way that meanwhile a deviation of the absolute humidity of a maximum of 10% below the maximum value is allowed. The course of the absolute humidity is therefore relatively flat.

In the aforementioned tumble dryer, which is designed to carry out the method described above, located in the air outlet from the load compartment, a humidity sensor, as is well known and, for example, from the above-mentioned prior art. It is connected to a control of the tumble dryer. This in turn is not only designed to record the measured values of the humidity sensor, but can also record the measured values or their course. Furthermore, the aforementioned values are stored in a memory of the controller for the said correlations. Finally, the control advantageously has a time recording for the time since the start of operation.

These and other features are apparent from the claims and from the description and drawings, wherein the individual features each individually or a plurality in the form of sub-combinations in one embodiment of the invention and on others Be realized areas and can represent advantageous and protectable versions for which protection is claimed here. The subdivision of the application into individual sections as well as intermediate headings does not restrict the general validity of the statements made thereunder.

Brief description of the drawings

Fig. 1

eine Innenansicht eines erfindungsgemäßen Wäschetrockners und

Fig. 2

ein Diagramm für verschiedene Verläufe der absoluten Luftfeuchtigkeit über der Zeit bei verschiedenen Beladungen an Wäschemenge für den Wäschetrockner gemäß Fig. 1.

An embodiment of the invention is shown schematically in the drawings and will be explained in more detail below. In the drawings show:

Fig. 1

an interior view of a clothes dryer according to the invention and

Fig. 2

a diagram for different profiles of the absolute humidity over time at different loads on laundry for the dryer according to FIG. 1.

Detailed description of the embodiments

In Fig. 1, an inventive clothes dryer 11 is shown. The presentation is limited to the functionally necessary parts and is merely intended to illustrate how these functionally essential parts of the tumble dryer work. In a load compartment 12 is laundry 14 with a residual moisture after washing or spinning. This cargo space is usually rotated or rotated, but this does not play a significant role for the invention. Air is introduced into the loading space 12 via an air inlet 16. The air flow is caused by the fan 17, 18 air is heated by the downstream heater for drying the laundry 14. Similarly, an air outlet 20 leads out of the load compartment 12 to the outside, which identifies the tumble dryer 11 as an exhaust air dryer. The Warm air is thus, as known from such dryers, fed to the laundry 14, absorbs moisture and transports it via the air outlet 20 to the outside, so as to dry the laundry.

To detect the absolute humidity of the exhaust air, a humidity sensor 22 is arranged in the air outlet 20. Such a humidity sensor 22 is known to the person skilled in the art and need not be explained in detail here. The humidity sensor 22 is connected to a controller 24, as well as the fan 17 and the heater 18. The controller 24 has a memory 25, possibly also integrated, in which various values can be stored, which will be discussed in more detail below.

Except for an exhaust air dryer 11 shown in Fig. 1, the invention can also be applied to a condensation dryer in a modified form. For this purpose, a corresponding moisture sensor is provided in an air outlet of the cargo space in front of a downstream condensation device. Thus, the absolute humidity in the exhaust air can be detected there as well.

In Fig. 2, several curves of the humidity over time are shown. The first course is for a case that in the clothes dryer 11 as shown in FIG. 1 in the hold 12 12 kg of laundry. The second course shows a drying process for 3 kg of laundry and the third course for 1.5 kg. In the first course, it is assumed that a scrubber moisture of 70% before the beginning of the drying process at the time t = 0 is given, in the other two courses a Wäscherestfeuchte of 50%. The difference in the courses is also due to the fact that the absolute humidity in the air outlet 20 depends on the surface of the laundry 14. The surface in turn depends on the amount of laundry or the weight. You just want to find out. So can be closed by the amount of absolute humidity on the amount of laundry.

It can be seen how all three courses are very similar at the beginning. Only after about 2 minutes, the third course for the smallest amount of laundry begins to fall, to reach a maximum at about 500 seconds or just over 8 minutes of operation. From this maximum it drops off with an approximately constant slope.

This means that at the beginning of the drying process, regardless of the amount of laundry, the detected by the humidity sensor 22 humidity in the air outlet 20 is the same. This is mainly due to the fact that, so to speak, during start-up of the tumble dryer 11, the maximum amount of moisture that can be removed from the laundry 14 is approximately the same.

The second course for 3 kg of laundry runs over a longer time the same as the first course, flattens after about 10 minutes significantly, and then take a not very pronounced maximum value, from which he falls again steeply after about 16 minutes.

The first course for 5 kg of laundry flattens off a little later than the second course, namely at about 12 to 14 minutes. It reaches a maximum value of just over 30 minutes. At a bit over 40 minutes, the course begins, first slowly and then fall slightly more again.

It is clear from the three courses for the humidity as a function of time according to FIG. 2 that these courses can be used by a person skilled in the art to distinguish and thus to determine the charge quantity. Under certain circumstances, they may alternatively or in addition to the determination of other values such as residual moisture odgl. be used.

In Fig. 2 each dashed line is shown, where or at which time a maximum value of the humidity is achieved. Stored corresponding values can be retrieved in the memory 25 from the controller 24. Thus, the controller 24 can already determine, based on the maximum values of the courses according to FIG. 2, how much laundry is approximately in the cargo space 12. Admittedly, however, especially in the course 1, the determination of a maximum value is subject to great inaccuracy. It does not need to be controlled exactly to one minute in the process of controlling the tumble dryer. An inaccuracy should stay within an area of a few minutes.

For the second curve with 3 kg of laundry is dotted marked, as the course would be if the residual moisture would be 70% as in the curve for 5kg. However, this dotted curve is only schematic. It should roughly illustrate how, instead of the approximately recognizable maximum of the curve, there is a wider, plateau-like course as well as the curve for 5 kg. Similarly, this would look for the 1.5kg curve.

It can be assumed that the width or duration of the plateau, although a statement about the residual moisture of the laundry after the washing process allows. However, this is again seen in comparison to the amount of laundry. Thus, such a plateau phase for the course at 1.5kg laundry is shorter than at 5kg laundry. If, for example, the residual moisture in curve 2 is still higher than the 70% corresponding to the dotted representation, then the plateau phase would be even longer or longer.

In this respect, according to a second possibility, also described above, the value of the absolute humidity after a certain time can be used. In the illustration according to FIG. 2, for example, a time of slightly more than 16 minutes is suitable here. At this time, the course 1 has not yet reached its maximum value, the course 2 is approaching its maximum value and the course 3 is already decreasing again. As can be seen, the courses at this time or a similar time are sufficiently different to be distinguished from one another by comparison.

According to yet another possibility, a gradient or the gradient of the course, in particular at a later time or after exceeding the respective maximum value, can be detected. For this purpose, either a fixed time can be provided, for example at about 16 minutes, to detect a course similar to that of course 3 yet. This is indicated by lines corresponding to the value for the gradient. Furthermore, it is possible, for example also for detecting the achievement of the maximum value, to detect the gradient substantially continuously. As soon as it has become recognizable and permanently negative, either exceeding the maximum is detected or a detection of the gradient then carried out is linked with the time of this detection and this in turn is compared with corresponding stored values.

According to yet another possibility of the invention can be waited for by exceeding the maximum by observing the current values for the absolute humidity. A certain time thereafter, for example a little less than 10 minutes thereafter, is used to then measure the gradient or gradient of the course. This also gives the certainty that there is a good and comparable value for the gradient.

According to yet another possibility of the invention may again be provided to detect the gradient continuously. It can then be detected the time at which the gradient assumes a certain value. Also, by this characteristic, at which time one of the courses of FIG. 2 has a certain slope, the courses can be different from each other and thus ultimately determine the amount of laundry 14 in the hold 12 of the clothes dryer 11 again. By combining the aforementioned detection options, it is also possible, inter alia, to draw conclusions about further values, such as, for example, scrubber moisture at the beginning of the drying process.

As soon as the amount of laundry 14 is known and possibly the other aforementioned values, the controller 24 can turn off the course of the drying process with respect to time, air supply and possibly air temperature. Thus, an optimized in terms of result and energy consumption drying process can be performed. Furthermore, it is possible that some of the determined values, in particular the amount of laundry and possibly even an existing residual moisture of the laundry in the load compartment 12, are displayed on a display on the tumble dryer 11 as information for a user.

Claims (12)

Method for determining the amount of charge of laundry (14) in a cargo space (12) with air outlet (20) of a tumble dryer, in particular an exhaust air dryer, wherein the absolute humidity in the air outlet (20) from the cargo space (12) is measured, characterized in that the amount of charge in the hold (12) is determined by determining the maximum value and / or the course of the absolute humidity in the air outlet (20) from the loading space (12). A method according to claim 1, characterized in that values for a correlation of maximum values of the absolute humidity with a certain amount of charge are stored for a comparison and from these values from the determined maximum value of the absolute humidity, the amount of charge in the hold (12) is determined. Method according to the preamble of claim 1, characterized in that the amount of charge in the cargo space (12) by determining a value of the absolute humidity in the air outlet (20) at a certain defined time after the start of operation of the tumble dryer (11) is determined. A method according to claim 3, characterized in that values for a correlation of arbitrary values of the absolute humidity at a certain time with a certain amount of charge are stored for a comparison and from these values from the determined value of the absolute humidity at a certain time the amount of charge in the loading space (12) is determined. A method according to claim 3 or 4, characterized in that the defined time is less than 40 minutes and more than 5 minutes after the start of operation of the tumble dryer (11), preferably about 15 to 20 minutes. Method according to the preamble of claim 1, characterized in that for determining the amount of charge in the hold (12) the time is taken at which the gradient of the absolute humidity assumes a certain value, and values for a correlation of values of the gradient to certain Time points are stored with a certain amount of charge for a comparison, on the basis of these values from the gradient at a certain time, the amount of charge of laundry (14) in the cargo space (12) is determined. A method according to claim 6, characterized in that the time is used, to which the gradient of the absolute humidity is approximately zero. A method according to claim 6, characterized in that the time is used, at which the gradient of the absolute humidity is lower or falls. A method according to claim 6, characterized in that the time is used at which the gradient of the absolute humidity falls sharply below zero. Method according to one of the preceding claims, characterized in that the time duration of a plateau-like course of the absolute humidity is determined and from this the residual moisture of the laundry is determined after washing, wherein for even longer periods of the plateau phase a higher residual moisture is assumed. A method according to claim 10, characterized in that the plateau phase is defined such that during the plateau phase, a deviation of the absolute humidity of a maximum of 10% below the maximum value is allowed. Laundry drier for performing the method according to any one of the preceding claims, characterized in that it comprises a memory (25) which is connected to the controller (24) for recording the measured values or their course.

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