Patent ID: 8278788

Claim:
A heat-generating portion cooling structure comprising: drawing means for drawing oil stored in a case into a catch tank provided in the case; and an oil circulation passage fowled in the case for circulating the oil in the case through the catch tank while the oil is being supplied to first and second heat-generating portions respectively positioned at one and the other sides of the catch tank, the oil circulation passage comprising a first passage for allowing the oil to flow down to the first heat-generating portion when a surface of the oil in the catch tank is raised to a first height and a second passage for allowing the oil to flow down to the second heat-generating portion when the surface of the oil in the catch tank is raised to a second height lower than the first height, wherein an amount of oil flowing down to the second heat-generating portion is greater than the amount of oil flowing down to the first heat-generating portion when the surface of the oil in the catch tank is raised to the second height while not being raised to the first height.