To optimize the load of a motor for assuring energy saving performance and washing performance by adjusting a water level in accordance with switching between a high speed operation and a normal operation of a drum.
A drum washing machine comprises: an air pump 5 for injecting air into air enclosing bags 4a and 4b fixed on a bottom of a water tank 2; an exhaust valve 6 for exhausting air from the air enclosing bags 4a and 4b; a drum 3 rotatably provided in the water tank 2 for housing laundry therein; a water level detecting part 7 for detecting a water level in the water tank 2; a motor 9 for rotatively driving the drum 3; and a control unit 8 for controlling entire components of the washing machine including the motor 9, the air pump 5 and the exhaust valve 6. The control unit 8 changes the water level of washing water in a washing step by expanding the air enclosing bags 4a and 4b when the drum 3 is rotated at a prescribed or lower rotational speed and shrinking the air enclosing bags 4a and 4b when the drum 3 is rotated at a rotational speed higher than the prescribed rotational speed.
Daisuke Nagano
Kentaro Fujii
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