Abstract: An apparatus for power steering of a vehicle, comprises: a worm gear arrangement including a worm shaft and a worm wheel engaged with the worm shaft; a bearing to support the worm shaft rotatably; a gear housing structure enclosing the worm gear arrangement, and defining a holder receiving portion; and a holder member arranged to hold the bearing, and fit movably radially in the holder receiving portion. A biasing mechanism urges the holder member or the bearing in a nearing direction toward the worm wheel. A buffer member is arranged to be compressed by the holder member when the holder member is moved in the nearing direction to buffer collision of the holder member in the holder receiving portion. The buffer member is set to have an elastic force smaller than the biasing elastic force of the biasing mechanism.

Abstract: Torque sensor detects torque of steering shaft formed by first and second shafts which are connected through torsion bar. Torque sensor has: a magnetic member provided at the first shaft and having magnetic poles alternately arranged in circumferential direction concentrically with rotation axis; a first yoke member provided at the second shaft and having (a) first nail portions arranged concentrically with the rotation axis and facing the magnetic member in radial direction and (b) a first ring portion; a second yoke member provided at the second shaft and having (c) second nail portions arranged concentrically with the rotation axis so that the first and second nail portions are alternately arranged in the circumferential direction and the second nail portions face the magnetic member in the radial direction and (d) a second ring portion arranged to be separated from and face the first ring portion; and a magnetic sensor.

Abstract: Torque sensor has: magnetic member; first yoke member having (a) first nail portions arranged concentrically to face the magnetic member in radial direction and (b) first ring portion; second yoke member having (c) second nail portions arranged concentrically so that the first and second nail portions are circumferentially alternately arranged and the second nail portions face the magnetic member in radial direction and (d) second ring portion; first magnetic flux concentration ring provided between the first and second ring portions; second magnetic flux concentration ring provided between the second ring portion and the first magnetic flux concentration ring; and magnetic sensor. The first and second magnetic flux concentration rings and the first and second ring portions are arranged in layers in radial direction. A part or all of axial direction area of the first and second magnetic flux concentration rings is surrounded and shielded by the second ring portion.

Abstract: A method of producing a rack is proposed, which comprises aligning a first bar piece, an intermediate piece and a second bar piece in order along a common axis; carrying out a first process in which the first and second bar pieces are stationarily held while showing a predetermined intersection angle between the first rack teeth on the first bar piece and the second rack teeth on the second bar piece; and carrying out a second process in which each of the first and second bar pieces and the intermediate piece are brought into contact with each other at mutually facing ends and subjected to a relative rotation therebetween for a friction welding thereby to join the first bar piece, the intermediate piece and the second bar piece together by the friction welding.

Abstract: Electric power steering system has steering mechanism; input and output shaft side rotation angle sensors detecting rotation angles of input and output shafts; operation circuit calculating command current for an electric motor; rotation direction judging circuit judging whether rotation directions of the input and output shafts are identical; advanced-phase judging circuit judging which phase of input and output shaft side rotation angle signals (S1, S2) is advanced; normal/reverse input judging circuit judging that (i) when both rotation directions are identical and S1 is advanced, input is normal input and (ii) when both rotation directions are identical and S2 is advanced, input is reverse input; and command current correcting circuit. The command current correcting circuit corrects the command current so that when the normal input is judged, torque in the same direction as input shaft rotation direction generated by the electric motor is greater than a case of reverse input judgment.