Characteristics investigation and verification of permanent magnet slip coupling for hydraulic power steering application

Abstract

Permanent magnet slip coupling (PMSC) is a kind of contactless transmission device with the advantages of clutch function, continuous speed regulation and no mechanical wear. The PMSC was introduced into the hydraulic power steering system (HPS) to regulate the steering pump speed so as to improve the steering stability and reduce the energy consumption. To evaluate the designed PMSC electromagnetic characteristics and dynamic characteristics of the PMSC were investigated and verified. Two-dimensional finite element model of the PMSC was built to investigate the electromagnetic characteristics. The simulation results of induced electromotive force, induced current and electromagnetic torque demonstrated that the PMSC had excellent electromagnetic characteristics. The speed regulation circuit of the PMSC was developed to investigate the dynamic characteristics. The results indicated that the PMSC had excellent dynamic characteristics under the condition of high load, inferior dynamic characteristics under the condition of low load. The bench tests were carried out to verify electromagnetic characteristics and dynamic characteristics of the PMSC. It can be seen that the test results of the induced electromotive force and output speed of the PMSC were in consistent with the simulation results. The real vehicle tests were conducted and the results demonstrated that the permanent magnet coupling based electronically controlled hydraulic power steering system (P-ECHPS) greatly improved low-speed steering maneuverability and high-speed steering stability of heavy-duty vehicles.