Patent ID: 8132636

Claim:
An in-wheel motor drive unit comprising: a casing; a motor part rotating and driving a motor-side rotation member, wherein the motor-side rotation member has an eccentric part; a deceleration part decelerating the rotation of said motor-side rotation member and transmitting the decelerated rotation to a wheel-side rotation member; a wheel hub fixedly connected to said wheel-side rotation member, which functions as an output member of the deceleration part; and a wheel hub bearing rotatably supporting said wheel hub with respect to said casing, wherein said wheel hub bearing includes: an external member having first and second outer track surfaces; said wheel-side rotation member having a first inner track surface opposite to said first outer track surface; said wheel hub having a second inner track surface opposite to said second outer track surface; and a plurality of rolling elements arranged between said first outer track surface and said first inner track surface, and between said second outer track surface and said second inner track surface, wherein the deceleration part includes: i) a revolution member rotatably retained in said eccentric part and making a revolution motion in accordance with the rotation of said motor-side rotation member, around a rotation axis of said motor-side rotation member ii) an outer periphery engagement part mechanically connected to said external member and engaging with the outer periphery of said revolution member to generate the rotation motion of said revolution member, iii) a hole provided on said revolution member; and iv) an inner pin fixed to said wheel-side rotation member and received into said hole; and further wherein the rotation motion of said revolution member is converted to the rotation motion of said inner pin engaging with the hole, around the rotation axis of said motor-side rotation member, and the rotation motion of said inner pin transmits to said wheel hub via said wheel-side rotation member.