Motor power steering system

Abstract

The present invention relates to a motor-driven power steering apparatus structured such as to apply a steering assist force generated by a motor to a steering system of a motor vehicle or a vehicle in accordance with a rotation force of an electric motor on the basis of a steering torque detected by a torque sensor. Further, the invention relates to a rotation angle sensor for detecting a rotation angle of a steering shaft, a detected portion of the rotation angle sensor is provided within the speed reduction gear, and a detecting portion of the rotation angle sensor is provided in a radial direction of the steering shaft and in an outer side of a bearing in the speed reduction gear.

1 . A motor-driven power steering apparatus structured such as to assist a steering force of a steering shaft via a transmission mechanism such as a gear of a speed reduction gear or the like by a rotation force of an electric motor on the basis of a steering torque detected by a torque sensor, comprising: 
 a rotation angle sensor for detecting a steering state of a steering wheel,    wherein a detected portion of said rotation angle sensor is provided within said speed reduction gear, and a detecting portion of said rotation angle sensor is provided in a radial direction of said steering shaft and in an outer side of a bearing in said speed reduction gear.    
     
     
         2 . A motor-driven power steering apparatus as claimed in  claim 1 , wherein said detected portion is arranged in a worm wheel within said speed reduction gear, and the rotation of said worm wheel is detected by said detecting portion.  
     
     
         3 . A motor-driven power steering apparatus as claimed in  claim 1 , wherein said detecting portion is mounted to a recess groove formed in any one side within the worm wheel within said speed reduction gear.  
     
     
         4 . A motor-driven power steering apparatus as claimed in  claim 1 , wherein said detecting portion is arranged at a position opposing to a side surface of said detected portion, thereby detecting a magnetic or optical angle signal from said detected portion.  
     
     
         5 . A motor-driven power steering apparatus as claimed in  claim 1 , wherein said detected portion is structured by a recess groove formed in any one side within the worm wheel within said speed reduction gear, and is constituted by a small gear provided in an inner peripheral surface of said recess groove.  
     
     
         6 . A motor-driven power steering apparatus as claimed in  claim 1 , wherein said rotation angle sensor is constituted by an annular detected portion provided in the side surface of the worm wheel within said speed reduction gear, and a detecting portion provided at a position opposing to said detected portion.  
     
     
         7 . A motor-driven power steering apparatus as claimed in  claim 1 , wherein said speed reduction gear is supported by a plurality of bearings.