There is provided a ball screw mechanism that can be kept compact even without a deflector. A ball screw mechanism (20) includes: a rack shaft (8), on the outer peripheral surface of which a spiral rack screw groove (21) is formed; a cylindrical nut (30), on the inner peripheral surface of which a spiral nut groove (32) that faces the rack screw groove is formed; and a plurality of balls (40) disposed in a rolling passage (R) that is a space surrounded by the rack screw groove (21) and the nut groove (32). The nut (30) is provided with: shift portions (34) provided at both ends of the nut groove (32) to shift the track of the nut groove (32) in the axial direction of the rack shaft from the rack screw groove and to displace the nut groove to be deeper in the radial direction of the rack shaft as the track is shifted; a circulation passage (33) that connects between the shift portions (34); and passage entrances (35) that each connect between the shift portion (34) and the circulation passage (33).
BALL SCREW MECHANISM AND STEERING DEVICE
2015-11-25
Patent
Elektronische Ressource
Englisch