Patent ID: 7059447
Filing Date: 2006-06-13
Classification: B62D,F16H

Abstract:
1. An automotive vehicle steering system comprising: a steered wheel; and an actuator for turning the steered wheel about a turning axis to steer the wheel; the actuator comprising a housing that comprises an interior enclosed by an axially extending side wall having opposite axial ends; a shaft that has a longitudinal axis coaxial with the housing side wall, an interior axial end disposed within the interior of the housing and an exterior axial end that is exterior to the interior of the housing; an electric motor comprising a rotor that is disposed within the interior of the housing for rotation about an axis that is coaxial with the shaft axis, the rotor comprising a cylindrical rotor tube comprising an open axial end through which the shaft coaxially passes, and which is rotatable about the coaxis of the shaft and rotor, the motor further comprising a stator for operating the rotor to rotate the rotor tube; an internal screw thread on the rotor tube; an external screw thread on the shaft; a set of transmission rollers operatively coupling the internal screw thread and the external screw thread to provide for bi-directional transmission of motion between the rotor tube and the shaft such that rotation of the rotor tube causes the shaft to move axially of the housing and axial motion of the shaft causes rotation of the rotor tube; and a coupling that couples the exterior axial end of the shaft to the wheel; wherein the transmission rollers comprise identical screw threads meshing with the internal and external screw threads, and in which the internal, external, and transmission roller screw threads all have the same number of threads per unit of axial length.