Method for determining imbalance in drum washing machine

Abstract

A method for determining an imbalance in a drum washing machine includes increasing a rotational speed of a motor of the drum washing machine to a target RPM, and then measuring an RPM for each rotation section; comparing the RPM for each rotation section to an RPM limit to obtain a comparison result; and determining whether an imbalance occurs according to the comparison result.

1 . A method for determining an imbalance in a drum washing machine, comprising:
 increasing a rotational speed of a motor of the drum washing machine to a target RPM, and then measuring an RPM for each rotation section of the motor;   comparing the RPM for each rotation section to an RPM limit to obtain a comparison result; and   determining whether an imbalance occurs according to the comparison result.   
     
     
         2 . The method of  claim 1 , wherein determining whether the imbalance occurs comprises determining that the imbalance occurs when the RPM for each rotation section deviates from the RPM limit. 
     
     
         3 . The method of  claim 1 , wherein determining whether the imbalance occurs further comprises determining a variation of the RPM for each rotation section when the RPM for each rotation section falls within the RPM limit. 
     
     
         4 . The method of  claim 3 , wherein when the variation of the RPM for each rotation section falls within a preset value, the imbalance does not occur. 
     
     
         5 . The method of  claim 3 , wherein when the variation of the RPM for each rotation section exceeds a preset value, the imbalance occurs. 
     
     
         6 . The method of  claim 1 , wherein the drum washing machine further comprises a control unit, a drum rotated by the motor, and a load measurement unit. 
     
     
         7 . The method of  claim 6 , wherein the control unit controls the motor and measures the rotational speed of the motor. 
     
     
         8 . The method of  claim 1 , wherein the load measurement unit measures a load of the motor caused by rotational movement of the drum. 
     
     
         9 . The method of  claim 1 , wherein the target RPM is a value of from 50 to 150 RPM. 
     
     
         10 . The method of  claim 1 , further comprising:
 allowing the motor and drum to freely rotate when the motor reaches the target RPM,   measuring a load of the motor for each of a plurality of rotation sections of the motor, and   measuring a rotational speed for each of the plurality of rotation sections based on the load of the motor.   
     
     
         11 . A method of spin-drying laundry in a drum washing machine, comprising:
 balance spin-drying the laundry by a process comprising:
 determining an imbalance in the drum washing machine according to the method of  claim 1 , and 
 removing wash water and/or foam from the laundry when no imbalance occurs; and 
   main spin-drying the laundry at a rotational speed higher than the target RPM.   
     
     
         12 . The method of  claim 11 , further comprising determining the imbalance when the laundry adheres to an inner wall of a drum rotated by the motor. 
     
     
         13 . The method of  claim 12 , wherein the target RPM is a value of from 50 to 150 RPM. 
     
     
         14 . The method of  claim 11 , further comprising agitating the laundry at a rotational speed less than the target RPM so that the laundry items do not concentrate onto one side of a drum rotated by the motor. 
     
     
         15 . The method of  claim 11 , further comprising, after removing wash water and/or foam from the laundry, determining again whether an imbalance occurs in the drum washing machine. 
     
     
         16 . The method of  claim 15 , wherein determining again whether an imbalance occurs in the drum washing machine comprises:
 changing the rotational speed of the motor to the target RPM, and then measuring a second RPM for each rotation section of the motor;   comparing the second RPM for each rotation section to the RPM limit to obtain a second comparison result; and   determining whether the imbalance occurs according to the second comparison result.   
     
     
         17 . The method of  claim 15 , wherein wash water and/or foam is removed from the laundry at a rotational speed higher than the target RPM. 
     
     
         18 . The method of  claim 17 , wherein wash water and/or foam is removed from the laundry at a rotational speed of from 125 to 250 RPM. 
     
     
         19 . The method of  claim 11 , wherein main spin-drying the laundry is performed at 200 to 400 RPM.