Patent ID: 8002076

Claim:
An electric power steering apparatus comprising: a motor including a rotor and a cylindrical stator provided to surround the rotor, the motor being adapted to assist in steering operations through a torque of the rotor, a motor control device including a drive unit which drives the motor, and a control unit which controls the motor, and a housing including a first region for accommodating therein the motor, a second region for accommodating therein the motor control device, and a partition wall that partitions the housing into the first region and the second region, wherein the partition wall is integrally formed with the housing, the drive unit includes a heat generating element, a heat radiating metal plate for radiating heat generated by the heat generating element, and an insulating layer fixed between the heat generating element and the heat radiating metal plate, the heat radiating metal plate being in surface contact with the partition wall such that the heat radiating metal plate has a plane extending between a circumferential wall of the first region, adjacent the partition wall, and the insulating layer, the heat generating element, the insulating layer, and the metal plate together forming a stacked structure by which heat generated by the heat generating element is conducted directly to the motor and then radiated away along a first path rather than by way of the control unit, the housing includes, as a part of the second region for accommodating therein the motor control device, a projecting portion formed to extend parallel with the heat radiation plane, and the control unit is accommodated away from the drive unit in a region defined by the projecting portion so that heat generated by the control unit is radiated directly along a second path to the outside of the housing.