Electric power steering assembly and method for fabricating same

Abstract

An electric power steering assembly includes an electric motor, a reduction mechanism for reducing the speed of an output rotation of the electric motor, and a reduction-mechanism housing accommodating therein the reduction mechanism. The electric motor includes: an output shaft rotatably supported by the reduction-mechanism housing, a motor housing formed integrally with the reduction-mechanism housing, a rotor, and a stator assembly accommodated in an annular space defined between the rotor and the motor housing. When the stator assembly is assembled in the annular space via an opening at an end portion of the motor housing, a guided portion on an outside circumference of a stator yoke is guided by a guide portion on an inside circumference of the motor housing.

1 . A method of fabricating an electric power steering assembly which comprises: 
 an electric motor providing steering assist;    a reduction mechanism for speed reduction of an output rotation of the electric motor; and    a reduction-mechanism housing accommodating therein the reduction mechanism,    the electric motor including: an output shaft rotatably supported by the reduction-mechanism housing; a rotor having an outer periphery and being rotatable integrally with the output shaft; a cylindrical motor housing having an inside circumference surrounding the outer periphery of the rotor; an annular space defined between the outer periphery of the rotor and the inside circumference of the motor housing; and an annular stator assembly accommodated in the annular space,    the motor housing being formed integrally with the reduction-mechanism housing;    the motor housing including an end portion disposed on an opposite side from the reduction-mechanism housing, the end portion of the motor housing defining an opening having a size to allow the stator assembly to be assembled in the motor housing,    the electric motor including a cover for closing the opening at the end portion of the motor housing,    the stator assembly including a cylindrical stator yoke having an inside circumference and an outside circumference, and being fixed in the motor housing,    the inside circumference of the motor housing including a guide portion, the outside circumference of the stator yoke including a guided portion,    the method comprising:    a first step of assembling a sub-assembly and the stator assembly, respectively, the sub-assembly including the reduction-mechanism housing, the output shaft, the rotor and the motor housing; and    a second step of assembling the sub-assembly and the stator assembly to each other;    the second step wherein the stator assembly is assembled in the annular space via the opening at the end portion of the motor housing in a manner that the guided portion of the stator yoke is guided by the guide portion of the motor housing thereby preventing the stator assembly from contacting the rotor.