Torque detection structure for power steering device, and power steering device using same

A power steering device, comprising:

• a steering mechanism comprising a steering shaft having an input shaft configured to rotate in synchronism with a steering operation of a steering wheel and an output shaft connected via a torsion bar to the input shaft such that rotation from the input shaft is transmitted to the output shaft, and a motion converter configured to convert rotation of the output shaft into a turning operation of steered road wheels;
• a housing having one axial opening formed on one axial side of opposite axial directions of a rotation axis of the steering shaft and configured to accommodate the output shaft in the housing;
• a ball bearing having an inner race, balls, and an outer race and inserted from the one axial opening and accommodated and disposed in the housing for rotatably supporting the output shaft in the housing;
• a fixing member formed into a circular-arc shape or an annular shape and inserted and disposed from the one axial opening into the housing and configured to fix the outer race to the housing with the fixing member fixed to the housing in a state where one end of the fixing member has been brought into abutted-engagement with the outer race;
• a torque sensor having an outside diameter set less than an inside diameter of the fixing member and configured to generate an electrical signal that changes in accordance with an amount of torsional deformation of the torsion bar, for detecting a driver's steering torque arising from the steering operation inputted to the input shaft;
• and
• an electric motor configured to apply a steering force to the steering mechanism responsively to the output signal from the torque sensor.