Patent ID: 7525224

Claim:
A drive unit including an electric motor, a drive unit casing accommodating therein the electric motor, an inverter that controls the electric motor, and a flow passage of a refrigerant that cools the inverter, the drive unit characterized in that the inverter is mounted on the drive unit casing such that a heat sink united with a substrate of the inverter defines a space on a portion thereof opposed to the drive unit casing, the space is communicated to the flow passage of the refrigerant, the heat sink comprises heat-sink side fins extending into the space toward the drive unit casing, separation means ( 6 ) for preventing thermal conduction is provided in the space, wherein the separation means comprises a plurality of separation members ( 60 ) with a space (R 3 ) there between, and both the heat-sink side fins and the drive unit casing contact directly with the separation means.