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Electro-Hydraulic power steering system


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  • Dynamic Performance
Nissan's new power steering system provides the natural, smooth feel of a sophisticated conventional hydraulic power steering system while simultaneously improving fuel economy by using electric power instead of drawing power from the engine*.
* Jointly developed with Hitachi Automotive Systems Co., Ltd.

System Configuration

Electro-Hydraulic power steering system

  1. Hydraulic assist
    (greater reduction ratio than with gears, etc.)
  2. 12V power supply
    (Since large reduction ratio possible, DC-DC converter for voltage step-up is not needed)
  3. Small cylinder diameter (50mm)
    (Motor does not need to be mounted on rack, since a large reduction ratio is obtained)

EPS powered directly by motor

  1. ehpss_EN_02.jpgMotor power directly assists steering
    (large reduction ratio not obtainable with worm gear or ball screw)
  2. 42V power supply
    (small reduction ratio means DC-DC converter needed to provide power)
  3. Large motor diameter(110mm)
    (to provide sufficient power, a large motor must be mounted on the rack shaft)

System Overview

Motor Power Converted to Hydraulic Pressure to Assist Steering

By providing power assist via hydraulic pressure, this system delivers a naturally smooth steering feel and, thanks to the
flexibility of control allowed by electric power, offers more precise steering power characteristics. It also improves fuel
economy since the electric powered pump operates only when steering assist is needed.