Washing machine with balancers and control method thereof

Abstract

Disclosed are a washing machine and a control method thereof capable of reincreasing a number of rotations of a motor after maintaining the number of rotations at a predetermined number before excessive vibration of a water tub, braking the motor when the water tub is vibrated at more than a predetermined vibration level, and reincreasing the number of rotations, thereby reducing the excessive vibration of the water tub. The control method includes detecting the number of rotations, determining whether the detected number of rotations has reached a predetermined number, controlling the motor such that the number of rotations is maintained at the predetermined number of rotations when it is determined that the detected number of rotations has reached the predetermined number, counting the time taken to maintain the number of rotations at the predetermined number of rotations, and increasing the number of rotations after a predetermined first time has elapsed.

1 . A control method of controlling a washing machine including a motor, a water tub, and balancers, the control method comprising:
 detecting a number of rotations of the motor during an operation of the washing machine;   determining whether the detected number of rotations of the motor has reached a predetermined number of rotations and, when it is determined that the detected number of rotations of the motor has reached the predetermined number of rotations, controlling the motor such that the number of rotations of the motor is maintained at the predetermined number of rotations;   counting a time taken to maintain the number of rotations of the motor at the predetermined number of rotations; and   increasing the number of rotations of the motor after a predetermined first time has elapsed.   
   
   
       2 . The control method according to  claim 1 , wherein the predetermined number of rotations is a number of rotations of the motor lower than a number of excessive vibration rotations of the water tub. 
   
   
       3 . The control method according to  claim 2 , wherein the number of excessive vibration rotations of the water tub is a number of rotations of the motor at a point where an excessive vibration of the water tub is generated due to a difference in a rotating speed between the rotary tub and balls in the balancers before the balls reach a balancing position. 
   
   
       4 . The control method according to  claim 1 , wherein the predetermined first time is a time necessary to maintain the number of rotations of the motor at the predetermined number of rotations until the balls reach a balancing position. 
   
   
       5 . The control method according to  claim 4 , wherein the increasing the number of rotations of the motor includes maintaining the number of rotations of the motor at the predetermined number of rotations for the predetermined first time until the balls reach the balancing position and increasing the number of rotations of the motor to a spin-drying RPM to perform a spin-drying operation of the washing machine. 
   
   
       6 . The control method according to  claim 1 , wherein the controlling the motor such that the number of rotations of the motor is maintained at the predetermined number of rotations includes maintaining the number of rotations of the motor at a predetermined number of rotations before an excessive vibration generating point of the water tub such that the motor passes through the excessive vibration generating point of the water tub generated during an operation of the washing machine. 
   
   
       7 . The control method according to  claim 1 , further comprising:
 detecting a vibration of the water tub generated as the number of rotations of the motor is increased;   braking the motor to lower the number of rotations of the motor when the detected vibration of the water tub exceeds a predetermined vibration level; and   counting a time after the braking of the motor and reincreasing the number of rotations of the motor after a predetermined second time has elapsed.   
   
   
       8 . The control method according to  claim 7 , wherein the detecting the vibration of the water tub includes detecting an excessive vibration of the water tub generated due to a difference in a rotating speed between the rotary tub and balls in the balancers before the balls reach a balancing position during the operation of the washing machine. 
   
   
       9 . The control method according to  claim 8 , wherein the braking the motor to lower the number of rotations of the motor includes lowering the number of rotations of the motor to a predetermined number of rotations to reduce the excessive vibration of the water tub generated before the balls reach the balancing position. 
   
   
       10 . The control method according to  claim 7 , wherein the reincreasing the number of rotations of the motor includes detecting a lowered number of rotations of the motor and, when the detected lowered number of rotations of the motor has reached a predetermined number of rotations, reincreasing the number of rotations of the motor to perform the operation. 
   
   
       11 . The control method according to  claim 7 , wherein the predetermined vibration level is reference vibration data as to an excessive vibration of the water tub. 
   
   
       12 . The control method according to  claim 7 , wherein the predetermined second time is previously set data used to locate an excessive vibration passing point of the water tub at a balancing position. 
   
   
       13 . The control method according to  claim 12 , wherein the reincreasing the number of rotations of the motor includes maintaining the number of rotations of the motor for the predetermined second time such that the excessive vibration passing point of the water tub is located at the balancing position after the braking of the motor and increasing the number of rotations of the motor to a spin-drying RPM to perform a spin-drying operation of the washing machine. 
   
   
       14 . A washing machine including a motor, a water tub, and balancers, the washing machine comprising:
 a rotational frequency detection unit detecting a number of rotations of the motor during an operation of the washing machine; and   a control unit determining whether the detected number of rotations of the motor has reached a predetermined number of rotations, controlling the motor such that the number of rotations of the motor is maintained at the predetermined number of rotations when it is determined that the detected number of rotations of the motor has reached the predetermined number of rotations, counting a time taken to maintain the number of rotations of the motor at the predetermined number of rotations, and increasing the number of rotations of the motor after a predetermined first time has elapsed.   
   
   
       15 . The washing machine according to  claim 14 , further comprising:
 a vibration detection unit detecting a vibration of the water tub generated by the rotation of the motor, wherein   the control unit brakes the motor to lower the number of rotations of the motor when the detected vibration of the water tub exceeds a predetermined vibration level, counts a time after the brake of the motor, and reincreases the number of rotations of the motor after a predetermined second time has elapsed.   
   
   
       16 . The method according to  claim 1 , wherein the operation is a spin-drying operation of the washing machine. 
   
   
       17 . The washing machine according to  claim 14 , wherein the operation is a spin-drying operation of the washing machine. 
   
   
       18 . A washing machine having a motor, balancers, balancing balls fitted within the balancers and a water tub, comprising:
 a rotation frequency detection unit detecting a number of rotations of the motor during an operation of the washing machine;   a vibration detection unit detecting a vibration of the water tub generated by the rotation of the motor; and   a control unit maintaining the number of rotations of the motor at a predetermined number of rotations before excessive vibration is generated from the water tub until the balancing balls reach a balancing position.   
   
   
       19 . The washing machine according to  claim 18 , wherein the control unit decreases the number of rotations of the motor by braking the motor when the detected vibration of the water tub exceeds a predetermined vibration level. 
   
   
       20 . The washing machine according to  claim 18 , wherein the control unit increases the number of rotations of the motor after a predetermined time has elapsed after the brake of the motor. 
   
   
       21 . A control method of controlling a washing machine having a motor, balancers, balancing balls fitted within the balancers and a water tub, comprising:
 braking the motor after beginning an operation of the washing machine and after detecting that a vibration of the water tub exceeds a predetermined vibration level; and   increasing a number of rotations of the motor after a predetermined time has elapsed in order to reduce excessive vibration of the water tub until the balancing balls reach a balancing position.