| 摘要 |
PROBLEM TO BE SOLVED: To provide an electric power steering device capable of preventing deterioration of the performance of a motor.SOLUTION: An electric power steering device 1 includes a rack shaft 15, a rotor body 40, a plurality of balls 61 and a motor 21. The rack shaft 15 has a rack screw groove 63 in the outer peripheral part 15A. The motor 21 has a stator 22 and a permanent magnet 31. The rotor body 40 has a nut screw groove 44 formed in the inner peripheral part 42. The rotor body 40 has a low magnetic permeability part 40A and a high magnetic permeability part 40B. The high magnetic permeability part 40 B is lower in carbon content than the low magnetic permeability part 40A and higher in magnetic permeability than the low magnetic permeability part 40A. The permanent magnet 31 is fixed to the high magnetic permeability part 40B. The plurality of balls 61 are arranged in a rolling path 60A formed by the rack screw groove 63 and the nut screw groove 44. |
