Patent ID: 6408987
Filing Date: 2002-06-25
Classification: B66B

Abstract:
An elevator guidance device, comprising:a guide rail installed in a vertical direction; a moveable body capable of being raised and lowered along said guide rail; an electromagnet mounted on said moveable body and including a plurality of magnetic poles that face said guide rails with a gap therebetween and which is arranged so that attractive forces that act on said guide rails at at least two of said plurality of magnetic poles are in mutually opposite directions; a plurality of magnetic units including a permanent magnet that supplies magnetomotive force needed for guidance of said moveable body and that is arranged so as to share a magnetic path with said electromagnets in said gap; sensors configured to detect a condition in said gap of a magnetic circuit formed by said electromagnets with said gap and said guide rail; a guidance control unit controlling an exciting current of said electromagnets in accordance with the output of said sensors and thereby stabilizing said magnetic circuits; a zero power control unit stabilizing said magnetic circuits in a condition wherein an exciting current of said electromagnets is zero, based on an output of said sensors; and an output limiting unit setting a prescribed saturation value for an output of said zero power control unit and if said output of said zero power control unit exceeds a range defined by said saturation value, and making said saturation value said output of said zero power control unit.