WATER PUMP

摘要

A water pump (10) so constituted as to perform noncontact transmission of rotation from a drive side rotating body (20), to which rotation of an engine is transmitted, to a driven side rotating body (30) which is provided with a pump impeller (31). The drive side rotating body (20) is provided with a negative pressure chamber (50), and a pair of permanent magnets (26a, 26b) arranged with different poles opposing. The driven side rotating body (30) is provided with an induction ring (32) having inductive portions (32b) interposed between the pair of permanent magnets (26a, 26b) at a predetermined interval. The pair of permanent magnets (26a, 26b) are moved with respect to the inductive portions (32b) in the direction of the axis of rotation by a negative pressure introduced into the negative pressure chamber (50), thus altering the amount of overlap (L1) in the direction of the axis of rotation of the pair of permanent magnets (26a, 26b) and the inductive portions (32b).