Method of Controlling a Rotatable-Drum Laundry Dryer and a Rotatable-Drum Laundry Dryer Implementing the Method

Abstract

A method is provided for controlling a drying operation of a rotatable-drum laundry dryer ( 1 ) having a rotatable drum ( 3 ) for loading laundry ( 5 ) and at least an electrode sensor ( 22 ) for sensing dryness of the laundry ( 5 ). The method includes the step of detecting the presence/absence of moist laundry ( 5 ) inside the rotatable drum ( 3 ) by the electrode sensor ( 22 ). If a presence of moist laundry inside the rotatable drum ( 3 ) is detected, a drying cycle is started. The dryness of the laundry ( 5 ) is sensed during the drying cycle and a cycle time (TD) at which the sensed dryness reaches a preset dryness threshold is measured. If the cycle time (TD) is lower than a preset dryness threshold time (Sm), the drying cycle is continued for a first additional time (D1), and the drying cycle is stopped at the end of the first additional time (D1).

1 . A method of controlling a drying operation of a rotatable-drum laundry dryer comprising a rotatable drum for loading laundry and at least one electrode sensor for sensing dryness of the laundry;
 the method comprising:
 detecting the presence/absence of moist laundry inside the rotatable drum by said at least one electrode sensor; 
 upon a presence of moist laundry inside the rotatable drum being detected, starting a drying cycle; 
 sensing dryness of the laundry during said drying cycle; 
 measuring a cycle time at which the sensed dryness reaches a preset dryness threshold; 
 upon the measured cycle time being lower than a preset dryness threshold time, continuing the drying cycle for a first additional time, and stopping the drying cycle at the end of said first additional time. 
   
     
     
         2 . The method according to  claim 1 , wherein said first additional time is such that the time elapsed from the beginning of said drying cycle to the stopping of the drying cycle is a preset minimum dryness time. 
     
     
         3 . The method according to  claim 1 , wherein said first additional time is set as the difference between said preset minimum dryness time and said cycle time. 
     
     
         4 . The method according to  claim 1 , further comprising:
 upon said cycle time being not lower than said preset dryness threshold time, continuing the drying cycle for a preset second additional time; and   stopping the drying cycle at the end of said second additional time.   
     
     
         5 . The method according to  claim 4 , wherein said second additional time is between zero and ten seconds. 
     
     
         6 . The method according to  claim 1 , wherein determining the presence/absence of moist laundry inside the rotatable-drum comprises:
 performing a starting detection phase for a starting detection time;   upon no moist laundry being detected during said starting detection time, performing one or more additional detection phases, each of which lasts an additional detection time; and   upon no moist laundry being detected during said additional detection phase/s, ending operation of the rotatable-drum laundry dryer.   
     
     
         7 . The method according to  claim 6 , wherein said additional detection time is less than said starting detection time. 
     
     
         8 . A rotatable-drum laundry drier comprising:
 a rotatable drum for loading laundry,   at least one electrode sensor for sensing dryness of the laundry;   drying air feeding means for feeding drying air into the drum, and rotation driving means for rotating the drum about an axis of rotation; and   electronic control means configured to:
 detect presence/absence of moist laundry inside the rotatable drum by said at least one electrode sensor; 
 if upon a presence of moist laundry inside rotatable drum being detected, start a drying cycle; 
 sensing dryness of the laundry during said drying cycle; 
 measure a cycle time at which the sensed dryness reaches a preset dryness threshold; and 
 upon the measured cycle time being lower than a preset dryness threshold time, continue to perform the drying cycle for a first additional time, and stop the drying cycle at the end of said first additional time. 
   
     
     
         9 . The dryer according to  claim 8 , wherein said first additional time is such that the time elapsed from the beginning of said drying cycle to the stopping of the drying cycle is a preset minimum dryness time. 
     
     
         10 . The dryer according to  claim 8 , wherein said first additional time is set as the difference between said preset minimum dryness time and said cycle time. 
     
     
         11 . The dryer according to  claim 8 , wherein said electronic control means are further configured to:
 continue to perform said drying cycle for a preset second additional dryness time if upon said cycle time being not lower than said preset dryness threshold time; and   stop the drying cycle at the end of said preset second increased cycle time.   
     
     
         12 . The dryer according to  claim 11 , wherein said second additional time is between zero and ten seconds. 
     
     
         13 . The dryer according to  claim 9 , wherein said electronic control means are further configured to:
 perform a starting detection phase for a starting detection time;   upon no moist laundry being detected within said starting detection time, perform one or more additional detection phases; and   upon no moist laundry being detected during said additional detection phase/s, end operation of rotatable-drum laundry drier.   
     
     
         14 . The dryer according to  claim 13 , wherein, each of said one or more additional detection phases lasts an additional detection time less than said starting detection time. 
     
     
         15 . The method according to  claim 2 , wherein said first additional time is set as the difference between said preset minimum dryness time and said cycle time. 
     
     
         16 . The method according to  claim 2 , further comprising:
 upon said cycle time being not lower than said preset dryness threshold time, continuing the drying cycle for a preset second additional time; and   stopping the drying cycle at the end of said second additional time.   
     
     
         17 . The method according to  claim 2 , wherein determining the presence/absence of moist laundry inside the rotatable-drum comprises:
 performing a starting detection phase for a starting detection time;   upon no moist laundry being detected during said starting detection time, performing one or more additional detection phases, each of which lasts an additional detection time; and   upon no moist laundry being detected during said additional detection phase/s, ending operation of the rotatable-drum laundry dryer.   
     
     
         18 . The dryer according to  claim 9 , wherein said first additional time is set as the difference between said preset minimum dryness time and said cycle time. 
     
     
         19 . The dryer according to  claim 9 , wherein said electronic control means are further configured to:
 continue to perform said drying cycle for a preset second additional dryness time upon said cycle time being not lower than said preset dryness threshold time; and   stop the drying cycle at the end of said preset second increased cycle time.   
     
     
         20 . The dryer according to  claim 9 , wherein said electronic control means are further configured to:
 perform a starting detection phase for a starting detection time;   upon no moist laundry being detected within said starting detection time, perform one or more additional detection phases; and   upon no moist laundry being detected during said additional detection phase/s, end operation of rotatable-drum laundry drier.