| 摘要 |
PURPOSE: An electric power steering system is provided to prevent swing of a central portion of a rack bar by improving support strength of the rack bar and to increase steering feeling by restricting the central portion of the rack bar from drooping and bending by load input from the outside. CONSTITUTION: An electric power steering system comprises a pinion(4) connected to a steering wheel; a rack bar(2) embedded in a rack housing(1) and composed of a rack gear(20) formed at one end and engaged with the pinion and a screw(22) disposed in the center; a first ball nut(6a) mounted to the screw by a plurality of steel balls(8a,8b); a motor(5) arranged to cross bias or rectangularly for a central shaft of the rack bar; and a gearing(100) for transmitting power from the motor to the first ball nut. One end of the rack bar is held by a support yoke(9) and a central portion and the other end are supported by the first ball nut and a second ball nut(6b). Therefore, the rack bar is supported at three spots.
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