Dewatering Machine

Abstract

A dewatering machine including an electric motor for rotating a dewatering drum and a control part. When the dewatering drum starts to rotate, the control part measures a load of the washings in the dewatering drum. Then, the control part rotates the motor at a first rotating speed by controlling a duty ratio of a voltage applied to the motor and then to rotates the motor at a second rotating speed higher than the first rotating speed. When the motor accelerates to the first rotating speed, the control part acquires a reference duty ratio at timing determined according to the measured load. Next, within a specified period, the control part determines whether the washings in the dewatering drum are biased according to an index indicating the change between the duty ratio and the reference duty ratio.

1 . A dewatering machine, comprising:
 a dewatering drum configured to accommodate washings and rotate to dewater the washings;   an electric motor configured to rotate the dewatering drum;   a load measuring unit configured to measure a load of the washings in the dewatering drum when the dewatering drum begins to rotate;   a drive control unit configured to, after the load measuring unit measures the load, rotate the motor constantly at a first rotating speed by controlling a duty ratio of a voltage applied to the motor and then rotate the motor constantly at a second rotating speed higher than the first rotating speed so as to dewater the washings formally;   an acquisition unit configure to acquire the duty ratio of the voltage applied to the motor as a reference duty ratio in an acceleration state in which the motor accelerates to the first rotating speed;   a timing determination unit configured to determine timing for the acquisition unit to acquire the reference duty ratio;   a determination unit configured to, in a specified period after the acquisition unit acquires the reference duty ratio, determine whether the washings in the dewatering drum are biased or not according to an index indicating a change between a duty ratio of the voltage applied to the motor to maintain the first rotating speed and the reference duty ratio; and   a stopping control unit configured to stop the rotation of the dewatering drum when the determination unit determines that the washings are biased,   wherein the timing determination unit determines the timing for the acquisition unit to acquire the reference duty ratio according to the load measured by the load measuring unit.   
     
     
         2 . The dewatering machine according to  claim 1 , wherein the dewatering machine comprises an execution unit configured to, after the stopping control unit stops the rotation of the dewatering drum, execute one of the following executions: a rotation of the dewatering drum for restart the dewatering of the washings and a processing for correcting the bias of the washings in the dewatering drum. 
     
     
         3 . The dewatering machine according to  claim 2 , wherein
 before the motor rotates constantly at the first rotating speed, the drive control unit rotates the motor constantly at a specified speed lower than the first rotating speed; and   the execution unit shortens the duration in which the motor rotates constantly at the specified speed when the execution unit executes the rotation of the dewatering drum for restart the dewatering of the washings.   
     
     
         4 . A dewatering machine, comprising:
 a dewatering drum configured to accommodate washings and rotate to dewater the washings;   an electric motor configured to rotate the dewatering drum;   a drive control unit configured to rotate the motor constantly at a first rotating speed by controlling a duty ratio of a voltage applied to the motor and then rotate the motor constantly at a second rotating speed higher than the first rotating speed so as to dewater the washings formally;   an acquisition unit configured to acquire a duty ratio every a specified time within a specified period after the motor begins to accelerate to the first rotating speed;   a counting unit configured to add 1 to a count value with an initial value of zero when the duty ratio acquired by the acquisition unit is greater than or equal to the duty ratio acquired last time and reset the count value to the initial value when the duty ratio acquired by the acquisition unit is smaller than the duty ratio acquired last time;   a determination unit configured to determine that the washings in the dewatering drum are biased when the count value is greater than or equal to a specified threshold; and   a stopping control unit configured to stop the rotation of the dewatering drum when the determination unit determines that the washings are biased.   
     
     
         5 . A dewatering machine, comprising:
 a dewatering drum configured to accommodate washings and rotate to dewater the washings;   an electric motor configured to rotate the dewatering drum;   a drive control unit configured to rotate the motor constantly at a first rotating speed by controlling a duty ratio of a voltage applied to the motor and then rotate the motor constantly at a second rotating speed higher than the first rotating speed so as to dewater the washings formally;   an acquisition unit configured to acquire a duty ratio every a specified time within a period when the rotating speed of the motor accelerates from the first rotating speed to a second rotating speed;   a determination unit configured to determine that the washings in the dewatering drum are biased when the duty ratio acquired by the acquisition unit is greater than or equal to a specified threshold;   a stopping control unit configured to stop the rotation of the dewatering drum when the determination unit determines that the washings are biased;   a receiving unit configured to receive a selection related to a dewatering condition of the washings; and   a threshold changing unit configured to change the threshold according to the selection related to the dewatering condition received by the receiving unit.   
     
     
         6 . A dewatering machine, comprising:
 a dewatering drum configured to accommodate washings and rotate to dewater the washings;   an electric motor configured to rotate the dewatering drum;   a drive control unit configured to rotate the motor constantly at a first rotating speed by controlling a duty ratio of a voltage applied to the motor and then rotate the motor constantly at a second rotating speed higher than the first rotating speed so as to dewater the washings formally;   an acquisition unit configured to acquire a maximum value of a duty ratio in an acceleration state in which the motor accelerates to the first rotating speed to serve as a maximum duty ratio;   a calculation unit configured to calculate an accumulated value of a difference between the duty ratio in every specified time and the maximum duty ratio after the acquisition unit acquires the maximum duty ratio;   a determination unit configured to determine that the washings in the dewatering drum are biased when the accumulated value is smaller than the specified threshold; and   a stopping control unit configured to stop the rotation of the dewatering drum when the determination unit determines that the washings are biased.   
     
     
         7 . The dewatering machine according to  claim 6 , wherein the threshold is calculated using an equation adopting a count value and the maximum duty ratio as variables, wherein the count value is added by 1 once every the specified time. 
     
     
         8 . The dewatering machine according to  claim 6 , wherein the drive control unit controls the duty ratio in the following way: in the acceleration state in which the motor accelerates to the first rotating speed, the drive control unit generates the maximum duty ratio when the rotating speed is slightly lower than a rotating speed at which the dewatering drum resonates. 
     
     
         9 . The dewatering machine according to  claim 7 , wherein the drive control unit controls the duty ratio in the following way: in the acceleration state in which the motor accelerates to the first rotating speed, the drive control unit generates the maximum duty ratio when the rotating speed is slightly lower than a rotating speed at which the dewatering drum resonates.