Patent ID: 7102260

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, wherein 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, and a thermally insulating intermediate member is interposed between mating surfaces of the heat sink and 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, the drive unit casing comprises drive-unit-casing side fins extending into the space toward the heat sink, the heat-sink side fins and the drive-unit-casing side fins are apart from each other, and the heat-sink side fins and the drive-unit-casing side fins cooperatively generate a common refrigerant flow pattern within the space.