Patent ID: 6256893
Filing Date: 2001-07-10
Classification: B62D

Abstract:
Power steering system for a vehicle having at least one steerable wheel (50) movable within a predetermined steering interval (A-Y-B) defined by a first extreme end position (A), a straight-ahead position (Y) and a second extreme end position (B), comprising a servo motor (56) for moving said wheel or wheels (50) within said steering interval (A-Y-B), a wheel position related steering control unit (58), and a wheel position identifying device (55,61) for providing calibrating signals to said control unit (58) in relation to said wheel or wheels (50) occupying either one of said first extreme end position (A), said second extreme end position (B) or said straight-ahead position (Y), said position identifying device (55,61) includes a disc shaped element (55) rotatable about a central axis (X) in unison with said wheel or wheels (50) and provided with a certain pattern of open portions (64,67,70) and closed portions (65,66,71), and an immobile sensing device (61) arranged to deliver signals to said control unit (58) in response to its alignment with said open and closed portions (64-67,70,71) at rotation of said disc shaped element (55),wherein said open portions (64,67,70) are formed by apertures in said disc shaped element (55) disposed at a common radius (Z) from said axis (X), said closed portions (65,66,71) being formed by those parts of said disc shaped element (55) that are located between said apertures (64,67,70) at said common radius (Z), and said sensing device (61) comprises a single sensor (61) located at said common radius (Z), whereina first one of said apertures (64) defines by its one end said straight-ahead position (Y) and by its other end said first extreme end position (A),a first one of said closed portions (65) extends from said straight-ahead position (Y) to said other extreme end position (B),a second one of said apertures (67) extends from said second extreme end position (B) to a position (D) located less than 10 degrees beyond said second extreme end position (B),a second one of said closed portions (66) extends from said first extreme end position (A) to a position (C) located less than 10 degrees beyond said first extreme end position (A),a third one of said apertures (70) extends over at least 20 degrees from said second closed portion (66), anda third one of said closed portions (71) extends over at least 20 degrees from said second aperture (67).