Patent ID: 8079828

Claim:
A water pump, configured such that rotation is transmitted in a non-contact condition from a drive-end rotation member whereto rotation is transmitted from an engine to a driven-end rotation member having a pump impeller, comprising: a pair of magnets provided on one of the drive-end rotation member and the driven-end rotation member so as to be mutually opposed with different polarities, a first magnet of the pair of magnets is disposed at a first radius from a central axis of the water pump and a second magnet of the pair of magnets is disposed at a second radius from the central axis of the water pump, the second radius being larger than the first radius; an induction body provided on the other of the drive-end rotation member and the driven-end rotation member so as to form a prescribed interval in between the pair of magnets; and a moving means moving at least one of the pair of magnets and the induction body with respect to the other of the pair of magnets and the induction body in an axial direction along a rotational axis and changing a degree of mutual overlap of the pair of magnets and the induction body in the axial direction.