Patent ID: 8127884

Claim:
An electric power steering apparatus comprising: a hollow shaft that is rotated through actuation of a motor, the hollow shaft having an end; a flange member screwed to the end of the hollow shaft; a rack shaft received in the hollow shaft in such a manner that the rack shaft is allowed to reciprocate in an axial direction, the rack shaft having an outer circumferential surface and a threaded groove formed in the outer circumferential surface; and a ball screw device that converts rotation of the hollow shaft into axial movement of the rack shaft, the ball screw device including: a ball screw nut arranged around the threaded groove of the rack shaft, the ball screw nut having an inner circumferential surface and a threaded groove formed in the inner circumferential surface; a helical raceway formed by arranging the threaded groove of the rack shaft and the threaded groove of the ball screw nut such that the grooves face each other; and a plurality of balls accommodated in the raceway, wherein the ball screw nut has an end and a flange formed at the end, the ball screw nut being fixed to the hollow shaft by fastening the flange to the flange member, the electric power steering apparatus further including a coupling member coupled to the ball screw nut and the hollow shaft, wherein the coupling member has a tubular portion and a flange portion, the tubular portion being fixed to the hollow shaft and having an end, and the flange portion extending radially outward from the end of the tubular portion and being fixed to the flange member.