PURPOSE: To reduce cost and simplify constitution by a method wherein a selvage part protruding from the outer peripheral surface of a casing is formed on a partition plate disposed between a casing and a casing cover and a heat generating electronic part is mounted on the selvage part.

CONSTITUTION: A selvage part 6-3 is formed in such a state to be protruded from a part of a partition plate 6 from the outer peripheral surface of a casing, and the electronic part 10 of a control circuit is mounted on the selvage part 6-3. A pumped-up liquid attributed to heat dissipation of an electronic part 10 of the electronic part 10 flows through an intake 7, formed in a casing cover 2, by means of a flow passage 3, formed in a casing cover 2, to a pump chamber 13 formed in a casing 1 partitioned by a partition plate 6 and connected to the flow passage 3 through the window 6-1 of the partition plate 6. Through rotation of an impeller 5 in a pump chamber 13, a flow from a pump chamber 13 to a tank part 4 on the casing cover 2 side through a different window is effected and delivery through a delivery port 8 is performed. This constitution dissipates the heat of the heat generating electronic part 10 through a partition plate 6 and the pumped-up liquid circulated in such a state to make direct contact with the partition plate 6.