Patent ID: 8360186

Claim:
An in-wheel motor drive device comprising: a motor part to rotatably drive a motor side rotation member; a reducer part to reduce rotation speed of said motor side rotation member and transmit it to a wheel side rotation member; a casing to hold said motor part and said reducer part; a wheel hub fixedly connected to said wheel side rotation member; and a reducer part lubricating mechanism to supply a lubricant oil to said reducer part, wherein said reducer part lubricating mechanism includes: a lubricant oil path provided in said motor side rotation member; a lubricant oil supply port extending from said lubricant oil path toward an outer diameter surface of said motor side rotation member; a lubricant oil discharge port provided in said casing to discharge the lubricant oil from said reducer part; a circulation oil path passing through said casing to connect said lubricant oil discharge port to said lubricant oil path, and to return the lubricant oil discharged from said lubricant oil discharge port to said lubricant oil path; a cooling water path provided in said casing so as be in contact with said circulation oil path to cool down the lubricant oil passing through the circulation oil path; and a partition member arranged in a contact position between said circulation oil path and said cooling water path, to separate them.