Patent ID: 6464034
Filing Date: 2002-10-15
Classification: B62D,F16H,Y10T

Abstract:
An electrically powered steering device which comprises:a housing; a steering shaft drivingly connected with a steering mechanism for steering wheels and extending completely through the housing; a motion translating mechanism for translating a rotary force exerted by a steering wheel into a force required to move the steering shaft in a direction axially of the steering shaft; a ball screw mechanism including a ball screw shaft constituting a portion of the steering shaft, and a rotary nut; and an electric drive motor mounted at one end on an outer periphery of the rotary nut of the ball screw mechanism: wherein said ball screw mechanism comprises the ball screw shaft having a spiral outer groove formed there around; the rotary nut formed with a spiral inner groove confronting to and aligned with the spiral outer groove on the ball screw shaft; a plurality of torque transmitting balls disposed in a series within a ball rolling guideway defined between the spiral outer groove on the ball screw shaft and the spiral inner groove in the rotary nut and for transmitting a force between the rotary nut and the steering shaft; and a rolling bearing mounted on an outer periphery of the rotary nut for rotatably supporting the rotary nut relative to the housing, and wherein the outer periphery of the rotary nut is formed integrally with a radially outwardly protruding positioning flange for positioning the rolling bearing mounted thereon; and wherein a ball circulating passage communicating with the ball rolling guideway at its respective opposite ends is formed in part in a nut body of the rotary nut and in part in at least one end cap secured to respective opposite ends of the nut body.