Washing machine

Abstract

A washing machine is provided. The washing machine adopts an induction motor to achieve efficient operation as that achieved by using a frequency converter. The washing machine includes: an input shaft configured to supply rotation power to a rotation part that rotates washings; an induction motor, configured to rotate in a forward direction and a backward direction and served as a power source of the rotation part; a transmission-arranged between an output shaft of the induction motor and the input shaft of the rotation part. The transmission is configured to change speed of the induction motor by decreasing a reduction ratio along with startup of the induction motor.

What is claimed is: 
     
         1 . A washing machine, comprising:
 an input shaft configured to supply rotation power to a rotation part that rotates washings;   an induction motor, wherein the induction motor is configured to rotate in a forward direction and a backward direction and is served as a power source of the rotation part; and   a transmission arranged between an output shaft of the induction motor and the input shaft of the rotation part, wherein the transmission is configured to change speed of the induction motor by decreasing a reduction ratio along with startup of the induction motor.   
     
     
         2 . The washing machine according to  claim 1 , wherein the transmission comprises:
 a variable driving side pulley unit arranged on a side of the output shaft;   a variable driven side pulley unit arranged on a the side of the input shaft; and   a driving belt capable of transferring the power between the variable driving side pulley unit and the variable driven side pulley unit,   wherein the transmission is configured to change a pulley diameter ratio according to rotating speed of the output shaft or the input shaft.   
     
     
         3 . The washing machine according to  claim 2 , further comprising a control part for driving the induction motor via a driver,
 wherein the control part is configured to, by taking a specified driving time preset for the rotation part and a specified inertial rotation time until the rotation part stops as working units, drive the rotation part in the backward direction repeatedly on the basis of each of the working units .   
     
     
         4 . The washing machine according to  claim 3 , wherein
 the specified driving time is set to be equal to or longer than a time during which change a gear ratio of the transmission changes from a maximum to a minimum.