EP0889155B1 - Method for detecting a dysfunction in a laundry dryer and laundry dryer using such a method - Google Patents

Description

The present invention relates to a method for detecting inadmissible operating states in a warm air dryer with a laundry drum and a dryer, in which such a process is implemented.

In conventional tumble dryers, there is usually a rotating drum existing laundry is dried in that by the drum and thus the Laundry is passed through a heated air stream that is capable of moist To remove laundry moisture, which gradually dries the laundry.

The supplied air flow is in a supply line in front of the drum by means of a suitable one Heater heats up, and is in the drum after crossing the laundry either discharged to the outside (exhaust air dryer) or a heat exchanger supplied, in which the air is cooled and the moisture precipitates as condensate.

With both types of laundry drying there are similar problems in terms of safe operation of the dryer.

The laundry dries in such a way that the supply air is heated and through the laundry flows, depending on the moisture level of the laundry and its own temperature removes a corresponding amount of moisture from the laundry. It is necessary that after reaching a certain degree of drying the laundry too large heating of the supply air flow and thus both overheating of the laundry on the one hand and overheating of the tumble dryer on the other hand is avoided.

A large number of solutions are specified in the prior art, but ultimately cannot satisfy.

DE-OS-16 10 314 describes a method for automatically controlling the drying process until a desired degree of dryness is reached the gradient of the rising temperature in a laundry drying system known, during or at the end of the drying process the difference between the temperatures of the supply air and the extract air is determined and the Change over time of this difference as a criterion for switching off the heating device is used. This procedure requires at least two temperature sensors a corresponding control, the control only permissible when exceeded The maximum temperature switches off the heating process.

DE-30 30 864 C2 describes a method for automatically controlling the drying process in a laundry drying system and a device for carrying it out known of the method in which a corresponding operating time in comparison is calculated with a fictitious operating time of the drying process, and the Drying process is controlled accordingly.

However, this method has the disadvantage that only when impermissible operating states are reached the drying process is switched off, which makes a possible Damage to both the laundry and the drying device cannot be excluded with certainty can be. From EP 0 312 072 A are the features of the preamble of the claim 1 known.

The present invention has for its object a method in The preamble of claim 1 to improve the type mentioned so far ahead such an inadmissible operating state when a critical operating state is reached is recognized and, if necessary, such an operating state well before it Reaching is prevented or can be prevented.

This object is solved by the features of claim 1. Preferred embodiments are in the dependent ones Claims 2 and 3 specified.

The present invention is also based on the object of a corresponding one To propose a tumble dryer, in which impermissible operating conditions are recognized in good time and can be prevented.

This object is achieved by the features of claim 4 solved.

According to the present invention, the recognition method becomes inadmissible Operating conditions in a tumble dryer the temperature in the supply air flow above the Supply air heating and periodically recorded in front of the laundry drum, from two successive a difference value (gradient) is formed, this difference value (Gradient) compared with a predetermined permissible difference value (gradient), where, if the newly formed difference value is greater than the predetermined permissible difference value is, a count is increased by one step, this count with a predetermined permissible count value is compared, and if the current count value is larger than the predetermined permissible count, the dryer of the dryer is switched off and / or a corresponding display is activated.

This ensures that impermissible operating states due to possible overheating can be avoided, by choosing the specified values, already far below the critical temperature level, the condition of the dryer can be detected can and a timely shutdown of the heating can take place, which makes a significant higher safety of the device in terms of avoiding thermal damage is achieved.

It also results in a component reduction compared to conventional dryers is possible. In particular, up to two heating levels can be omitted.

It is possible together with the method according to the invention to record different operating states of too high temperature, which result from different Areas.

In general, the overheating of the supply air flow can be determined as such or Such a risk of overheating in good time before the too high temperature is reached can be recognized and appropriate countermeasures, especially that Turning off the heater, done, causing damage to components and also the laundry in the dryer can be safely avoided.

In addition to the detection of the pure overheating value of the supply air also a detection of a clogged lint filter with the inventive Procedure carried out because an improperly added lint filter corresponding increase in the temperature of the air flow due to reduced Flow speed or increased flow resistance of the device result Has. With the same heating output, higher temperatures can be reached more quickly be recorded and in any case in time according to the method according to the invention can lead to the heating being switched off and furthermore an indication of the indication beforehand of a clogged lint filter.

The process according to the invention can be used with great advantage both in the case of condensation dryers as well as used in exhaust air dryers, making it universal for use can come.

The temperature of the supply air flow from the start of the drying process is particularly advantageous to detected, whereby the entire temperature profile in the dryer is detected becomes.

The process for recognizing impermissible operating conditions in a clothes dryer has a control method in which, according to a flow chart, the measured Values can be compared with specified values. This will be advantageous periodically successively recorded temperature difference values (gradients) with at least compared to a permissible overheating difference value (gradient). Surrendered that the determined difference value is smaller than the permissible overheating difference or gradient value, this current difference value is included compared to a second predetermined permissible difference value, that of a permissible Corresponds to temperature increase, which results from a lint filter clogging.

It is determined that the difference value determined is smaller than the permissible fluff filter temperature increase difference value the lint filter count is increased by one Count value increased, the newly formed lint filter count with a predetermined lint filter count compared and if the newly formed lint filter count is greater than that predefined lint filter count value, the display of the lint filter blockage is activated.

This results in particular advantageous that in the two-stage described above Process both the overheating of the supply air flow on the one hand and the fluff filter clogging on the other hand, so that not only the heating of the dryer can be turned off in time, but also an additional signal is available stands, which indicates the lint filter clogging in time. After that is the operator the tumble dryer is able to clean the fluff filter a prompt display based on the preselected values specified for fluff filter cleaning well before its total blockage can be, and thus the dryer always in a satisfactory and energy-saving operating state can work.

The present invention advantageously further relates to a tumble dryer a drum to hold the laundry to be dried, a blower to generate it an air flow that is passed through the laundry to be dried, a heater for heating the supplied air flow and a temperature sensor in the supply air duct, which is in the section between the heating of the supply air flow and the drum the dryer. A control is implemented in this tumble dryer, which is able to carry out the procedure for recognizing impermissible operating states.

Further details, features and advantages of the invention result from the following Description of an embodiment of the method or with Such a method working clothes dryer.

Fig. 1

einen Teilschnitt durch einen Wäschetrockner zeigt, der sowohl die Variante eines Abluftwäschetrocknertyps (durchgezogene Linien) als auch den Typ eines Kondensationswäschetrockners mit Umluftprinzip (gestrichelte Linien) zeigt;

Fig. 2

ein Ablaufdiagramm zeigt, daß die zweistufige Verfahrensweise des erfindungsgemäßen Erkennungsverfahrens zeigt, bei dem sowohl eine Überhitzung des Zuluftstromes einerseits als auch eine Flusensiebverstopfung andererseits angezeigt bzw. zur Steuerung der Heizung verwendet wird.

Reference is made to drawings in which:

Fig. 1

shows a partial section through a tumble dryer, which shows both the variant of an exhaust air dryer type (solid lines) and the type of a condensation dryer with a circulating air principle (dashed lines);

Fig. 2

a flowchart shows that the two-stage procedure of the detection method according to the invention shows, in which both an overheating of the supply air flow on the one hand and a lint filter clogging on the other hand is displayed or used to control the heating.

FIG. 1 shows a clothes dryer 1 according to the invention in a partial sectional view. In its upper part, this has a program control device 3 which is adjustable by an operating handle 5 and preferably a fuzzy processor control may contain (not shown).

The dryer has a laundry drum 7 in the usual way, which has a Pot 9 is accessible from a loading door 11 and through which the laundry in the Drum 7 can be inserted and removed again.

A supply air opening 13 is arranged on the lower rear side of the clothes dryer 1, which draws air from outside via a blower 15 and flows into a supply air duct 17 leaves. The fresh supply air continues to flow from the supply air duct 17 via a heating device 19 to the entrance 21 of the laundry drum 7. The supply air passes through the laundry drum 7 and flows at the outlet 23 through an exhaust air duct 25 and one inserted into this exhaust air duct Fluff filter 26 to an exhaust air outlet 27, from where it flows back into the open. The tumble dryer 1 thus described works according to the exhaust air principle.

However, the drying air circuit can also be used to form a circulating air dryer are closed, the exhaust air being guided from the exhaust air duct 25 to a condenser 29 becomes. The condenser 29 is designed as a heat exchanger in which the moist Exhaust air is cooled down and the increased air humidity condenses accordingly. This Air is then conveyed again through the fan 15 into the supply air duct 17. The Condensate can be removed from the tumble dryer at a suitable point, not shown be drained off or pumped into a condensate container from which it is hand is removable.

Be constructive to form a condensation dryer running in recirculation mode the manifold 28 of the exhaust duct 25 and the fan 15 turned over and connected to the respective nozzle 31 or 32 of the capacitor 29.

A temperature sensor 33 is arranged in the air duct above the heating device 19, which periodically detects the temperature of the air at predetermined time intervals and the Measured value supplies a corresponding control device (not shown).

The detailed description of the method according to the invention now relates on Fig. 2. There is shown a block diagram illustrating the sequence of the invention Process for detecting inadmissible operating states shows.

In step 101, control begins by a sensed temperature difference value, or a temperature gradient for processing in the controller. In one Step 103 checks whether the difference value of step 101 is acceptable Area is. If this is not the case, the program returns to the beginning.

In step 105, a value Z1 is read in, which is the permissible count of the temperature before overheating. In step 107, a value Z2 is read in which the permissible count before the lint filter clogging to be signaled corresponds.

In step 109 it is checked whether Z1 is equal to zero. If this is the case, the program runs in a step 111, which initiates the deactivation of the gradient method, by setting the temperature count to zero. Then in one Step 113 set the counter to zero and in step 115 the count value of the periodic Temperature measurement also set to zero. Then in a step 117 an overheating signal is also set to zero and the program returns to Beginning back.

If the value Z1 is not equal to zero in step 109, then a step 119 checks whether the dryer has started. If this is not the case, the program continues with steps 113 to 117 and returns to the beginning. If the dryer is active, it is checked in a subsequent step 121 whether the fluff filter signal is already present is set. If this is the case, the program returns to the beginning. Is this not the case, it is checked in a step 123 whether the overheating signal or the fluff filter overheating signal is set. If this is the case, the program returns back to the beginning. If this is not the case, a check is carried out in a next step 125 whether the set timer has already expired or not If it has not yet expired, so the program also returns to the beginning. But if the timer has already expired, the program then continues in a step 127 by checking whether it already exists there is an old temperature value. If this is not the case, then the current temperature value saved as the initial temperature value (step 129) and the timer restarted (Step 131). Then the program returns to the beginning, and a second The temperature value is determined.

However, if there is already an old value, the program runs after step 127 in Step 133 by adding a temperature difference Δϑ or a temperature gradient ϑ / t is set. In a subsequent step 135 it is checked whether the temperature difference Δϑ is less than zero. If this is the case, the program continues in step 129. If this is not the case, the program continues in step 137, in which it is checked whether whether Δϑ is greater than the permissible superheat difference value or not. If not If so, it is checked in a subsequent step 139 whether Δϑ is greater than a difference value is the difference resulting from a blockage of the fluff filter. is if this is not the case, the program continues in step 129. If this is the case, go the program continues in step 141, in which the count value for the fluff filter clogging "one" is increased or incremented.

If it is determined in step 137 that the current temperature difference value Δϑ or Gradient ϑ / t is greater than the permissible superheat difference value, so in one subsequent step 140 before step 141 the count value of the overheating by "one" increased or incremented. In a step 143 it is checked whether the count value is larger than the allowable count Z2. If this is the case, the program continues in step 145 continues, in which the fluff filter signal is set and the indication "fluff" flashes becomes. This will make the operator feel the condition of a clogged lint filter displayed. The program then goes back to the beginning. If the value is less than Z2, then it is checked in a subsequent step 147 whether the count value is greater than the permissible Overheating count Z1. If this is not the case, the program runs in Step 129 continues. If this is the case, the overheating signal is opened in a step 149 "1" set and the heating switched off accordingly. Then the program goes via step 150 back to the beginning.

As can be seen from the foregoing description, in one embodiment of the inventive method, both the overheating of the supply air flow with the help of a first gradient comparison as well as in a second gradient comparison a possible lint filter clogging determined.

With the method according to the invention for detecting inadmissible operating states in a tumble dryer is thus created due to of the temperature rise well before actually reaching a too high one Temperature to detect the condition of the dryer and the heating in time switch off before the temperature is too high. Not only that Components of the dryer itself but also those in the drum Laundry items safely protected from overheating. In addition to a lint filter blockage can also by means of the inventive method any other obstruction of the air flow within the air duct is detected become.

Claims (4)

1. Method of recognising impermissible operational states in a hot-air laundry drier (1) with a laundry drum (7), in which the temperature in the feed air flow above a feed air heater (19) and in front of the laundry drum (7) is periodically detected, a different value (Δϑ) or a gradient (Δϑ/t) is formed from values detected at respective successive instants in time, and this difference value, i.e. gradient, is compared with a predetermined difference value, i.e. gradient, characterised in that if the newly formed difference value (Δϑ) is greater as an absolute than the predetermined difference value a count value is increased by one step, this count value is compared with a predetermined count value (Z1, Z2), that if the actual count value is greater than the predetermined count value (Z1; Z2) the heating of the laundry drier is switched off and/or an operational state indication is activated and that if the ascertained temperature difference value (Δϑ) is smaller than the permissible excess heating difference value the actual temperature difference value (Δϑ) is compared with a second predetermined permissible temperature difference value which corresponds with a permissible temperature increase which results due to a lint filter blockage.
2. Method according to claim 1, characterised in that the temperature (ϑ) of the feed air flow is detected from the start of the drying process.
3. Method according to one of claims 1 and 2, characterised in that if the ascertained difference value (Δϑ) is smaller than the permissible lint filter temperature difference value the lint filter count value is increased by a count value, the newly formed lint filter count value is compared with a predetermined lint filter count value (Z2) and if the newly formed lint filter count value is greater than the predetermined lint filter count value (Z2) the indication or statement of the lint filter blockage is activated.
4. Hot-air laundry drier (1) with a laundry drum (7) for reception of laundry to be dried, a fan (15) for producing an air flow which is guided through the laundry to be dried, a heater (19) for heating the supplied air flow, and a temperature sensor (33) in the feed air channel, which is disposed in the section between the heater (19) of the feed air flow and the laundry drum (7), characterised in that the laundry drier comprises a control which is equipped for recognition of impermissible operational states, wherein the temperature in the feed air flow is periodically detected above a feed air heater (19) and in front of the laundry drum (7), a difference value (Δϑ) or a gradient (Δϑ/t) is formed from values detected at respective successive instants in time, and this difference value, i.e. gradient, is compared with a predetermined difference value, i.e. gradient, and that if the newly formed difference value (Δϑ) is greater as an absolute than the predetermined difference value a count value is increased by one step, this count value is compared with a predetermined count value (Z1; Z2), that if the actual count value is greater than the predetermined count value (Z1; Z2) the heating of the laundry drier is switched off and/or an operational state indication is activated and that if the ascertained temperature difference value (Δϑ) is smaller than the permissible excess heating difference value the actual temperature difference value (Δϑ) is compared with a second predetermined permissible temperature difference value which corresponds with a permissible temperature increase which results by reason of a lint filter blockage.

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