Dishwasher

A dishwasher comprising:

• a tub;
• an upper rack and a lower rack arranged in the tub and configured to receive objects;
• a lower arm comprising:
• a lower arm chamber configured to receive water into the lower arm chamber;
• a detachable pipe chamber configured to receive water from the lower arm chamber via a chamber communication hole located in a chamber partition wall that separates the lower arm chamber from the detachable pipe chamber;
• and
• an arm channel arranged to receive water from the lower arm chamber via an arm channel communication hole located in the arm channel and configured to eject water to the lower rack;
• a water supply pump configured to supply water to the lower arm chamber;
• a tower nozzle configured to eject water toward the upper rack;
• a tower connection part arranged to supply water received from the detachable pipe chamber to the tower nozzle and being detachable from the detachable pipe chamber;
• and
• a channel change unit provided in the lower arm chamber and configured to alternately open (i) the chamber communication hole and (ii) the arm channel communication hole in response to changes in water pressure inside the lower arm chamber,
• wherein the channel change unit comprises:
• a change unit body configured to reciprocate along a straight line and rotate in the lower arm chamber in response to changes in the water pressure inside the lower arm chamber;
• and
• a flange that extends around an outer circumferential surface of the change unit body, that is configured to guide the change unit body during reciprocation and rotation by contacting an inner circumferential surface of the lower arm chamber, and that comprises a plurality of projections that are configured to prevent foreign substances from being plugged between the flange and the lower arm chamber.