Research on a novel ECHPS system for heavy-duty commercial vehicles

A novel electronically controlled hydraulic power steering system (ECHPS) was proposed, which was characterized by the combined solenoid valves module in parallel with general steering gear. Four bypass flow controlling states were available according to vehicle speed, gaining variable assisted force characteristic. Based on the basic principle, the controller was designed, including power supply module, speed signal conditioning module, voltage comparison module, logic operation module, and valve driver module. Under the software of Multisim, the simulation analysis of controller hardware circuit was implemented. The bench tests were finally carried out to evaluate the performance of the controller and ECHPS system. The results of the tests indicate that the controller functions reliably, the obvious variation of assisted force characteristic not only reserves the low-speed steering maneuverability but also improves high-speed steering road feel, and further advances the vehicles' steering stability and driving safety.