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EP-4321677-B1 - METHOD FOR REMOVING FOREIGN OBJECTS FROM LAUNDRY IN A LAUNDRY DRYING APPLIANCE AND LAUNDRY DRYING APPLIANCE

EP4321677B1EP 4321677 B1EP4321677 B1EP 4321677B1EP-4321677-B1

Inventors

  • OSSO, Roberto
  • Ragogna, Roberto
  • ZOPPE, Giuliana

Dates

Publication Date
20260506
Application Date
20220809

Claims (13)

  1. Laundry drying appliance (1), in particular tumble dryer, comprising: • a rotatable drum (12) arranged to receive laundry; • a drying air conveying element (18) configured to convey drying air into the drum (12); • a drive unit (26) operatively coupled to the drum (12) and to the conveying element (18) and configured to variably drive the drum (12) about an axis of rotation of the drum (12) and the conveying element (18) so that an increase in a speed of the drive unit (26) results in an increase of a rotational drum speed and in an increase of a flow rate of drying air conveyed by the conveying element (18) and so that a decrease in a speed of the drive unit (26) results in a decrease of the rotational drum speed and in a decrease of the flow rate of drying air conveyed by the conveying element (18); • a humidity sensing unit (44) configured to detect a humidity value (HV) of the laundry received in the drum (12); • a control unit (30) configured to control operation of the drive unit (26) according to a foreign objects removal mode which comprises: ∘ step 1: decreasing the speed of the drive unit (26) from a high-speed state, in which the drive unit (26) is operated to rotate the drum (12) at a first rotational drum speed and to drive the conveying element (18) to output a first flow rate of drying air, to a low-speed state, in which the drive unit (26) is operated to rotate the drum (12) at a second rotational drum speed and to drive the conveying element (18) to output a second flow rate of drying air, wherein the first rotational drum speed is higher than the second rotational drum speed and the first flow rate of drying air is higher than the second flow rate of drying air, and ∘ step 2: increasing the speed of the drive unit (26) from the low-speed state to the high-speed state; characterized in that the control unit (30) and/or the humidity sensing unit is/are configured to determine whether the detected humidity value is below a first humidity threshold (HTH1) and wherein the control unit (30) is configured to start operation of the drive unit (26) in the foreign objects removal mode in response to detecting the humidity value to be below the first humidity threshold (HTH1).
  2. Laundry drying appliance (1) according to claim 1, wherein the control unit (30) is configured to control operation of the drive unit (26) such that step 1 and step 2 are repeated, in particular immediately one after another, alternatingly for multiple times.
  3. Laundry drying appliance (1) according to any one of the preceding claims, wherein the conveying element (18) comprises a fan impeller operably coupled to the drive unit (26), wherein the drive unit (26) is configured to drive the fan impeller about an axis of rotation of the fan impeller, such that the drive unit (26) can drive the drum (12) and the fan impeller so that the rotational drum speed and a rotational fan impeller speed are directly proportional to each other.
  4. Laundry drying appliance (1) according to any one of the preceding claims, wherein the drive unit (26) comprises a motor operatively coupled, in particular via one common motor shaft, to the drum (12) and to the conveying element (18), in particular to the fan impeller.
  5. Laundry drying appliance (1) according to any one of the preceding claims, wherein the laundry drying appliance (1) further comprises: • a heating device (40, 42) configured to heat the drying air to be conveyed by the conveying element (18) into the drum (12); in particular wherein the control unit (30) is configured to control operation of the heating device (40, 42) and/or configured to receive and to process data from the humidity sensing unit related to the humidity value.
  6. Laundry drying appliance (1) according to claim 5, wherein the control unit (30) is configured to reduce or to switch off a heating output of the heating device (40, 42) in response to detecting the humidity value to be below the first humidity threshold (HTH1), or wherein the control unit (30) is configured to reduce or to switch off a heating output of the heating device (40, 42) in response to detecting the humidity value (HV) to be below a second humidity threshold (HTH2) which is lower than the first humidity threshold (HTH1).
  7. Laundry drying appliance (1) according to any one of the preceding claims, wherein the first humidity threshold (HTH1) is less than 50%, in particular less than 20%, preferably less than 10%, more preferably between 2% and 10%, wherein 100% corresponds to completely wet laundry and 0% corresponds to completely dry laundry, and/or wherein the second humidity threshold (HTH2) is less than 30%, in particular less than 15%, preferably less than 5%, more preferably less than 2%, most preferably less than 1%, wherein 100% corresponds to completely wet laundry and 0% corresponds to completely dry laundry.
  8. Laundry drying appliance (1) according to any one of the claims 5 to 7, wherein the heating device (40, 42) comprises a heat pump, and/or wherein the heating device (40, 42) comprises at least one electric heater, in particular including at least one radiant heating element.
  9. Method for removing foreign objects from laundry in a laundry drying appliance (1), in particular in a laundry drying appliance (1) according to any of the preceding claims, wherein the laundry drying appliance (1) comprises: • a rotatable drum (12) arranged to receive laundry; • a drying air conveying element (18) configured to convey drying air into the drum (12); • a drive unit (26) operatively coupled to the drum (12) and to the conveying element (18) and configured to variably drive the drum (12) about an axis of rotation of the drum (12) and the conveying element (18) so that an increase in a speed of the drive unit (26) results in an increase of a rotational drum speed and in an increase of a flow rate of drying air conveyed by the conveying element (18) and so that a decrease in a speed of the drive unit (26) results in a decrease of the rotational drum speed and in a decrease of the flow rate of drying air conveyed by the conveying element (18); • a humidity sensing unit (44) configured to detect a humidity value (HV) of the laundry received in the drum (12); • a heating device (40; 42) configured to heat the drying air to be conveyed by the conveying element (18) into the drum (12); • a control unit (30) configured to control operation of the drive unit (26); wherein the method comprises operating the drive unit (26) in a foreign objects removal mode, comprising the following steps: step 1: decreasing the speed of the drive unit (26) from a high-speed state in which the drive unit (26) is operated to rotate the drum (12) at a first rotational drum speed and to drive the conveying element (18) to output a first flow rate of drying air, to a low-speed state in which the drive unit (26) is operated to rotate the drum (12) at a second rotational drum speed and to drive the conveying element (18) to output a second flow rate of drying air, wherein the first rotational drum speed is higher than the second rotational drum speed and the first flow rate of drying air is higher than the second flow rate of drying air; step 2: increasing the speed of the drive unit (26) from the low-speed state to the high-speed state; characterized in that the control unit (30) and/or the humidity sensing unit is/are configured to determine whether the detected humidity value (HV) is below a first humidity threshold (HTH1), wherein the method further comprises: • detecting a humidity value (HV) of the laundry received in the drum (12); and • operating the drive unit (26) in the foreign objects removal mode in response to detecting the humidity value (HV) being below the first humidity threshold (HTH1).
  10. Method according to claim 9, wherein step 1 and step 2 are repeated, in particular immediately one after another, alternatingly for multiple times, in particular wherein step 1 is carried for a period of less than 10min, preferably between 10s and 5min, optionally between 30s and 2min, and/or in particular wherein step 2 is carried for a period of less than 10min, preferably between 10s and 5min, optionally between 30s and 2min, and/or in particular a rate of change during step 1 and/or during step 2 is higher than 2rpm/min, preferably in average between 5rpm/min and 200rpm/min, optionally in average between 10rpm/min and 100rpm/min.
  11. Method according to claim 9 or claim 10, wherein the method further comprises: • reducing or switching off the heating output of the heating device (40, 42) in response to detecting the humidity value (HV) being below the first humidity threshold (HTH1); or • reducing or switching off the heating output of the heating device (40, 42) in response to detecting the humidity value (HV) being below a second humidity threshold (HTH2) which is lower than the first humidity threshold (HTH1).
  12. Method according to any one of the claims 9 to 11, wherein the first rotational drum speed is in the range between 55rpm to 90rpm, in particular in the range between 55rpm to 80rpm, preferably in the range between 55rpm to 65rpm, and/or wherein the second rotational drum speed is in the range between 20rpm to 50rpm, in particular in the range between 30rpm to 50rpm, preferably in the range between 35rpm to 45rpm, and/or wherein the difference between the first rotational drum speed and the second rotational drum speed is at least 10rpm, in particular at least 15rpm, preferably at least 20rpm, more preferably at least 25rpm.
  13. Method according to any one of the claims 9 to 12, wherein the method further comprises, prior to any previous step: • drying the laundry received in the drum (12) by: rotating the drum (12), switching on the heating output of the heating device (40, 42), and conveying drying air heated by the heating output into the drum (12).

Description

The present invention relates to a method for removing foreign objects from laundry in a laundry drying appliance and to a laundry drying appliance. Laundry drying appliance, such as tumble dryers or washer/dryers are commonly used to dry wet laundry. In the case of washer/dryers, the laundry can be washed and dried in the same appliance. EP 2 990 524 A1 discloses a laundry dryer including: a drum for receiving a load to be dried, said drum being apt to rotate around a rotational axis, a process air conduit in fluid communication with the drum where a process air stream is apt to flow, a heat pump system for heating up the process air, the drum is rotated by means of a motor, wherein the motor may define a motor axis, which may be the axis of a shaft of the motor. Furthermore, the motor may also drive a main fan of the air process circuit which blows the process air into the drum. EP 2 663 685 B1 discloses a method for operating a clothes treating apparatus comprising a hot air supplying unit (provided with a heater and a blowing device, and having a drying function of drying clothes by supplying hot air into a drum by use of the hot air supplying unit, the method comprising: rotating the drum with the clothes introduced therein; and supplying hot air into the drum by using the heater and the blowing device while the drum is rotated, wherein an air flow rate supplied by the blowing device changes during the hot air supplying step, wherein the hot air supplying step comprises: a first drying step of increasing an inner temperature of the drum; a second drying step of constantly maintaining the inner temperature of the drum after the first drying step; and a third drying step of re-increasing the inner temperature of the drum after the second drying step, wherein the air flow rate changes during the second drying step. It is further known from this document to provide an air flow rate changing step that comprises increasing the air flow rate up to a second air flow rate; maintaining the second air flow rate for a preset time, and decreasing the air flow rate down to a first air flow rate, wherein the second air flow rate is higher than the first air flow rate. At the same time, the rotating speed of the drum may be reduced when the second air flow rate is supplied, and the rotating speed of the drum is recovered to the original state when the first air flow rate is supplied. Briefly summarized, it is disclosed to operate a clothes treating apparatus at a first lower air flow rate with a high rotating speed of the drum and at a second higher air flow rate with a low rotating speed of the drum. The technical objects solved by the teaching of this document are set out as providing a clothes treatment apparatus capable of reducing a drying time and minimizing damages on the clothes by allowing uniform drying of the clothes introduced. Further, the generation of wrinkles shall be minimized. DE 10 2013 008 483 A1 discloses a hair and lint scraper with a rubber surface and weighting as an addition to a tumble dryer, especially for removing animal hair from fabric surfaces. The scraper is placed in a tumble dryer together with pieces of fabric and/or laundry to be freed from particles. The necessary scraping movement is created by the inertia and centrifugal force of the scraper during rotation of the tumble dryer drum. The object removal effect is achieved on all known animal hairs, such as those most commonly found on dogs, cats, rodents and hoofed animals and also human hair. The object removal process should be carried out before a washing process. EP 3 124 689 A1 discloses a method for operating a heat-pump dryer during a drying program. The method provides: starting a drying program, monitoring the temperature of the heat pump system, and if the temperature of the heat pump system is at or above a first threshold value, deactivating the compressor and reducing at least one of: a) the drying air fan rotational speed, b) the drying air fan conveyance rate, and/or c) the drum rotational speed. EP 2 738 303 A1 relates to a method for controlling a drying cycle of a laundry dryer. The method comprises the steps of: starting a drying cycle; performing the drying cycle; detecting an electric resistance and/or conductivity of the laundry during the drying cycle for estimating a dryness level of the laundry; comparing the electric resistance and/or conductivity of the laundry with an end cycle condition; finishing the drying cycle, if the end cycle condition is fulfilled. The end cycle condition depends on the rotation speed of the laundry drum and/or on the rotation speed of the air stream fan. EP 2 716 810 A1 relates to a method for controlling a drying cycle of a laundry dryer in dependence of the amount of load inside a laundry drum, comprising the steps of: detecting an electric resistance and/or an electric conductivity between two or more electrodes at least partly contacting the laundry inside the laundry drum a