Electro-Hydraulic power steering system
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
-
Hydraulic
assist
(greater reduction ratio than with gears, etc.) -
12V
power
supply
(Since large reduction ratio possible, DC-DC converter for voltage step-up is not needed) -
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
-
Motor
power
directly
assists
steering
(large reduction ratio not obtainable with worm gear or ball screw) -
42V
power
supply
(small reduction ratio means DC-DC converter needed to provide power) -
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.
