Patent ID: 7462017

Claim:
A dish-washing machine incorporating a fluid circulation device, comprising: a centrifugal pump being rotated by a bidirectional motor with undifferentiated rotation direction, wherein said pump has a predetermined optimum hydraulic efficiency depending on the rotation direction such that when the centrifugal pump rotates in one direction, the fluid motion is in a highest speed condition and the fluid has a pressure and a flow rate being much higher than a pressure and flow rate that occurs when the centrifugal pump rotates in an opposite direction; starting means of the motor to rotate the pump in either direction; and control and commutation means to cyclically interrupt and start the bidirectional motor power feeding for as many times as to increase the possibility of starting the motor, at least one or more times within a predetermined time interval, in the rotation direction corresponding to said predetermined optimum hydraulic efficiency of the centrifugal pump; wherein both the highest speed condition and a lowest speed condition can be obtained in the fluid circulation device for performing a washing program.