Washing machine

A washing machine, comprising:

• an outer tub provided to accommodate wash water therein;
• an inner tub located in the outer tub, the inner tub including a hub base at a lower side thereof, the inner tub being provided to accommodate laundry therein;
• a pulsator located in the inner tub;
• an outer shaft configured to be engaged with the hub base and to rotate the inner tub, the outer shaft having a hollow portion therein;
• an inner shaft located in the outer shaft, the inner shaft being configured to rotate the pulsator;
• a motor configured to rotate the inner shaft;
• a planetary gear train provided between the motor and the inner shaft to transfer torque of the motor to the inner shaft;
• a gear housing coupled to the outer shaft to accommodate the planetary gear train therein;
• and
• a clutch located in the hollow portion of the outer shaft, the clutch being configured to selectively transmit rotation of the inner shaft to the outer shaft,
• wherein the planetary gear train comprises:
• a ring gear fixed to an inner circumferential surface of the gear housing;
• a sun gear connected to a drive shaft of the motor;
• a plurality of pinion gears engaged with the sun gear and the ring gear;
• and
• a carrier rotatably supporting the plurality of pinion gears, the carrier being configured to rotate when the plurality of pinion gears revolve around the ring gear,
• wherein the clutch and the inner shaft are interconnected by a threaded interface, and the clutch and the outer shaft are interconnected by an anti-rotation interface, so that rotation of the inner shaft with respect to the outer shaft in a first direction raises the clutch along the anti-rotation interface within the outer shaft according to relative rotation of the threaded interface, and rotation of the inner shaft with respect to the outer shaft in a second direction lowers the clutch along the anti-rotating interface within the outer shaft according to relative rotation of the threaded interface,
• wherein, when the inner shaft rotates in the first direction and the clutch reaches a predetermined upper position, the clutch is restrained from being raised further, further by an upper stopper, and the clutch rotates in the first direction with the anti-rotating interface and the outer shaft rotates in the first direction together with the inner shaft, and
• wherein, when the inner shaft rotates in the second direction and the clutch reaches a predetermined lower position, the clutch is restrained from being lowered further, further by a lower stopper, and the clutch rotates in the second direction with the anti-rotating interface and the outer shaft rotates in the second direction together with the inner shaft.