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A drive unit comprises an electric motor 1, a drive unit casing 2 accommodating therein the electric motor, an inverter 3 that controls the electric motor, and a flow passage of a refrigerant that cools the inverter. The inverter is mounted on a heat sink 53 and mounted to the drive unit casing with

A drive unit comprises an electric motor 1, a drive unit casing 2 accommodating therein the electric motor, an inverter 3 that controls the electric motor, and a flow passage of a refrigerant that cools the inverter. The inverter is mounted on a heat sink 53 and mounted to the drive unit casing with a space R defined, and the space is communicated to the flow passage of the refrigerant. The heat sink comprises fins 56, and the drive unit casing comprises fins 22, the both fins being apart from each other. Thereby, both a side of the drive unit casing and a side of the heat sink are effectively cooled by heat exchange with a cooling refrigerant in wide areas. Also, the fins are apart from each other whereby direct heat conduction is avoided and efficient cooling is enabled with temperature gradient conformed to heat-resistant temperatures.

대표청구항 ▼

The invention claimed is: 1. 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

The invention claimed is: 1. 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. 2. The drive unit according to claim 1 wherein one of the heat-sink side fins and the drive-unit-casing side fins comprises rib-shaped fins and the other of them comprises pin-shaped fins. 3. The drive unit according to claim 1, wherein the heat-sink side fins and the drive-unit-casing side fins cooperatively and substantially cross the space with a minute gap therebetween. 4. The drive unit according to claim 3 wherein the heat-sink side fins and the drive-unit-casing side fins comprise the same fins. 5. The drive unit according to claim 4, wherein both the heat-sink side fins and the drive-unit-casing side fins comprise pin-shaped fins. 6. The drive unit according to claim 3, wherein the heat-sink side fins and the drive-unit-casing side fins comprise the same fins. 7. The drive unit according to claim 1, wherein the heat-sink side fins and the drive-unit-casing side fins comprise the same fins. 8. The drive unit according to claim 7, wherein both the heat-sink side fins and the drive-unit-casing side fins comprise pin-shaped fins. 9. The drive unit according to claim 7, wherein the heat-sink side fins and the drive-unit-casing side fins cooperatively and substantially cross the space with a minute gap therebetween. 10. The drive unit according to claim 9, wherein both the heat-sink side fins and the drive-unit-casing side fins comprise pin-shaped fins. 11. The drive unit according to claim 1, wherein both the heat-sink side fins and the drive-unit-casing side fins comprise pin-shaped fins. 12. The drive unit according to claim 1, wherein the intermediate member forms a seal between the mating surfaces of the heat sink and the drive unit casing. 13. 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 only 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, and the heat-sink side fins and the drive-unit-casing side fins are apart from each other.