前桥摆转式四驱底盘背压控制系统研究

摘要

Driven by a hydraulic open loop system,which consisted of engine-CVT-fixed displacement pump and fixed displacement wheel-motors,a 4WD front-axle articulated vehicle is needed to solve the problem when it is walking in negative loads situation.Currently,most of the hydraulic traveling machinery with open-loop system uses the counterbalance valve to control the negative loads.However,traditional counterbalance valves still have the problems of high cost,difficult maintenance and high power consumption.To solve these problems,a vehicle simulation model was built and tested.The control system included an electro-proportional relief valve,a pressure sensor and electronic control system with programmable processor.The electro-proportional relief valve was mounted on the outlet port of the hydraulic system.The pressure sensor was installed on the inlet port of the traveling motors.By reading the signal of the pressure sensor,and adjusting the cracking pressure of the electro-proportional relief valve to realize the hydraulic motors meter-out flow control.The results showed that this system can correctly judge the driver's intension,improve energy efficiency by reducing the cracking pressure when the vehicle working in positive load.When the vehicle working in negative load,the system would choose the suitable cracking pressure to meet the driver's expectations and keep the hydraulic motors from overrunning.%前桥摆转式四驱底盘采用发动机-CVT-定量泵为动力源,轮边液压马达为驱动装置的开式液压阀控系统驱动,需要解决底盘在负负载工况下马达超速的问题.为此,提出一种通过对行走马达进油压力实时监测实现液压系统回油背压控制策略,并根据该控制策略为该底盘设计了一回油背压控制系统.通过AMEsim构建了整机的液压力学模型,分析了行走马达在不同工况下的液压特性,制定了回油背压控制策略.对背压控制系统进行了软硬件的设计,并进行样机试验,验证了该系统控制策略的正确性.实现了样机在正负载行驶时能得到最低的回油背压,保证能量利用最大化;样机在负负载行驶时,选择合适的回油背压,确保液压马达在安全范围内运转.