Electromotive Drive Device and Electrically-Powered Steering Device

An electric power steering device comprising:

• an electric motor structured to apply a steering assist force to a steering shaft, depending on an output from a torque sensor, wherein the torque sensor is structured to sense a direction of rotation of the steering shaft and a rotating torque applied to the steering shaft;
• a motor housing structured to house the electric motor, wherein the motor housing includes an end face part opposite to an output part of a rotating shaft of the electric motor;
• an electronic control part arranged at the end face part of the motor housing, and configured to drive the electric motor, wherein the electronic control part includes a control circuit part, a power supply circuit part, and a power conversion circuit part;
• a metal cover made of aluminum-based metal and structured to cover the electronic control part;
• wherein
• one of the metal cover and the end face part of the motor housing includes an outer peripheral surface including a stepped portion having a radially inward recess form extending annularly;
• the stepped portion includes a fit portion where an opening portion of the metal cover is fitted;
• and
• the fit portion is formed with a friction stir welding portion where the motor housing and the metal cover are welded together.