EPS SYSTEM : System Description

• EPS system controls the power steering solenoid valve through the power steering control unit.
• The valve driving voltage to control the power steering solenoid valve varies according to the vehicle speed.
  Fig 1: Solenoid Valve Voltage Versus Vehicle Speed Graph

  Courtesy of NISSAN MOTOR CO., U.S.A.

CONTROL DIAGRAM

Fig 2: EPS System Control Diagram

Courtesy of NISSAN MOTOR CO., U.S.A.

CROSS-SECTIONAL VIEW

Fig 3: Cross-Sectional View Of EPS System

Courtesy of NISSAN MOTOR CO., U.S.A.

OPERATION PRINCIPLE

During Parking (When Turning The Steering Wheel To The Right.)

Fig 4: EPS System Operation Principle Diagram (Parking)

Courtesy of NISSAN MOTOR CO., U.S.A.

1. Power steering solenoid valve is closed while a vehicle is stopped.
2. Pinion "1R", "2R" and "3R" are closed depending on steering torque of steering wheel.
3. Oil pressure "P" in the gear housing assembly is the sum of oil pressures occurred in "2R" and "3R". This results in a light steering force because of high pressure.

During High-speed Operation

Fig 5: EPS System Operation Principle Diagram (High-Speed Operation)

Courtesy of NISSAN MOTOR CO., U.S.A.

1. Power steering solenoid valve is opened during high-speed operation.
2. Pinion "1R", "2R" and "3R" are closed depending on steering torque of steering wheel.
3. Oil pressure "2R" does not occur because the power steering solenoid valve is on full throttle.
4. Oil pressure "P" in the gear housing assembly includes only oil pressure occurred in "3R" and results in a heavy steering force.