Electromagnetic and Torque Characteristics of Electromagnetic Slip Coupling Applied to Hydraulic Power Steering System for Heavy-Duty Vehicles

摘要

An Electromagnetic Slip Coupling (ESC) is utilized in hydraulic power steering (HPS) to adjust the revolution speed for variable discharge flow of steering pump as well as on-demand power transferring from engine to steering pump. Unlike traditional electromagnetic slipping clutch, the proposed ESC is constructed of primary motor, auxiliary motor and energy recycle apparatus, which can recycle the slip energy. The model of ESC is established and the dynamic characteristics of primary motor and auxiliary motor are studied. In order to find out the electromagnetic characteristics of ESC, air gap magnetic field is simulated in time domain and frequency domain. To eliminate or minify harmonic component, wyes connected, short-chord and distributed windings are applied as well as oblique poles and skewed slots. Upon the assist characteristics of steering system, output torque of ESC is derived. Based on the ESC model, the torque characteristics of ESC are simulated and torque distributions of primary motor and auxiliary motor under steering situation and straight driving situation are conducted respectively. Significantly, the study on electromagnetic and torque characteristics provide the basis for the ESC control.