SUBARU

PINION ASSIST ELECTRIC POWER STEERING (PEPS)

TECHNOLOGY USED

       Building on the success of CEPS, Nexteer Automotive introduced EPS designs for pinion-assist and rack-assist EPS in 2007 for a wide range of vehicles. Pinion EPS has been in production since 2009.  PEPS and REPS have expanded the application range and flexibility for electronic power steering technology

     Instead of providing power assist through the steering column below the dash, within the passenger compartment. Nexteer Automotive Pinion Assist EPS (PEPS) system has the integrated controller-motor unit and assists mechanism on the steering gear pinion shaft.  PEPS have a design range comparable to Column Assist EPS, but offers original equipment manufacturer (OEMs) packaging flexibility.

Example PEPS

SYSTEM COMPONENT

1. Electric Motor :  Electric motors convert electric current into a rotational torque.

2. Electronic control units (ECU) : Electronic control unit (ECU) calculates the assisting power needed based on the torque being applied to the steering wheel by the driver, the steering wheel position and the vehicle’s speed.

Example of ECU

3. Drive pinion : Translating the rotational motion of the pinion into the linear motion of the rack.

Example of Drive Pinion

4. Steering rack : The steering rack produces linear motion from an applied torque to the pinion.

5. Torque sensor : The sensor records the torsion bar angle required for the steering movement.

Example of Torque Sensor

6. Steering angle sensor : The steering angle sensor, located on the combination switch, detects the steering angle degree and the neutral position, and transmits these to the system ECU.

Example of Steering Angle Sensor

7. Steering Shaft : The shaft, in the steering column, which transmits the rotation imparted to the steering wheel by the operator to the steering device.

SYSTEM OPERATION

            The PEPS electronic control unit (ECU) calculates the assisting power needed based on the torque being applied to the steering wheel by the driver, the steering wheel position and the vehicle’s speed. The EPS motor rotates a steering gear with an applied force that reduces the torque required from the driver.

Diagram of PEPS

BENEFIT OF TECHNOLOGY

• The power assist unit is attached to the steering gear pinion shaft.
• Waterproof construction.
• This steering system is provided with a power assist unit at the pinion shaft (inside the engine room) and it features calmness when compared with the column type.
• The power assist unit is outside the vehicle's passenger compartment, allowing assist torque to be increased greatly without raising interior noise.
• Combined with a variable-ratio steering gear, this system can suffice with a compact motor and offer superior handling characteristics.