New Electrical Power Steering Systems

Abstract

Abstract Electric‐power‐assisted steering ( EPAS ) systems replace hydraulic systems in a broad range of vehicle categories because of the fuel efficiency of this technology and the wide range of opportunities for new functional applications. This chapter illustrates the various types of EPAS systems and their application range and explains the requirements to meet performance, comfort, and safety goals as well as the technologies applied. Basically, the steering system is divided into subsystems. The mechanical system including the EPAS column, the intermediate shaft, and the steering gear has to ensure the safe transfer of torque from the steering wheel to the tie rods. A precise conversion from the steering wheel angle to the wheel angle as well as a comfortable steering feeling and adjustment mechanism is realized in this system. The electrical subsystem detects the driver's steering request and transfers it into assistance torque for each driving condition, respecting the vehicle and steering system dynamics. Furthermore, advanced steering functions are implemented in modern EPAS systems to improve the comfort of driving and to support vehicle functionalities. This chapter gives a detailed overview of the mechanical and electrical system components and their principle concept based on a column EPAS system from the global steering system supplier NSK . Finally, a brief overview is given about safety regulations and the corresponding system approach.