客车旁通流量控制式ECHPS系统仿真与台架试验

Simulation and bench test on by-pass flow control type ECHPS for large bus

针对大客车采用固定助力特性的液压助力转向系统(HPS)存在高速时因转向盘路感不足而危害操纵安全性的问题,研究了一种具有可变助力特性的流量控制式电控液压助力转向系统(ECHPS)。运用AMESim和Simulink软件,分别建立了ECHPS系统的液压机械模型和控制模型,提出了基于前馈补偿PID算法的基本助力控制与附加力矩控制相结合的控制模式。运用所建的联合仿真模型,分别对电液比例阀电流-车速特性、不同车速下的助力特性和附加力矩控制效果进行了仿真分析。基于搭建的ECHPS系统试验台,进行了助力特性测试。仿真与试验结果表明:助力特性曲线一致,验证了该模型的正确性及控制策略的有效性。

A flow-controlled system with alterable assist Electrical Controlled Hydraulic Power Steering （ECHPS） characteristics was introduced for solving the problem of in adequate steering feeling in high speed caused by Hydraulic Power Steering （HPS） with fixed assist characteristics in heavy-duty commercial vehicles. The combined simulation model of ECHPS was established using AMESim and Simulink software, including the hydraulic and mechanical model in AMESim and the control strategy model in Simulink. The ECHPS controller was studied, containing basic control and additional torque control based on feedforward compensation PID control algorithm. The simulations were analyzed according to the combined model, including the current-vehicle speeds characteristics, assist characteristics curves of the ECHPS system and effect of additional torque control strategy. The test of ECHPS steering assistant characteristic was carried out on the developed bench. The results show that the assist characteristics is the same as simulation and this verifies the correctness of ECHPS model and the effectiveness of designed control strategy.