交变负载下工程柴油机液压转矩均衡控制模型及试验研究

Modeling and Experimental Study on Hydraulic Torque Compensation Control System for Diesel Engine under the Alternating load

根据液压挖掘机等工程机械的工作特点,分析在交变负载工况下对柴油机进行转矩均衡控制的必要性,仿照大多数工程机械所采用的并联式油电混合动力结构,建立以蓄能器、蓄能泵、助力电动机等液压元件为核心的转矩均衡控制系统的数学模型,以带有全程调速器的485小型柴油机为控制对象,在调速拉杆固定的条件下将柴油机输出转矩设为控制目标,以齿轮泵和比例溢流阀为负载进行建模并开发出转矩均衡控制算法,并进行计算机仿真和台架试验。仿真和试验结果表明,所建数学模型基本反映了实际系统的特性,柴油机转速和输出转矩、蓄能器压力、负载转矩等仿真参数的变化趋势与试验结果一致,所开发的控制算法在多种试验负载下都能完成对柴油机输出转矩和转速的稳定控制。台架负载对比试验表明,在不同工况下转矩均衡控制能使柴油机的耗油率降低10%～20%不等,对短时间峰值负载的驱动能力提高了60%以上。

According to the characteristics of construction machine such as hydraulic excavator,the necessity of torque compensation control system for diesel engine under the alternating load is analyzed.Based on the structure of parallel hydraulic-electrical hybrid system,a hydraulic control model mainly composed of pump,motor and accumulator is established,and the corresponding control method is developed.The engine torque control experiment is performed on a test rig where a 485 model diesel engine with full-range speed governor is used as control object.With the engine speed control lever being fixed in simulation and experiment process,the test data such as engine torque,engine speed,load torque and accumulator pressure show that the hydraulic control model can appropriately represent the real device characteristics.It also illustrates that the engine torque and speed can be controlled in steady state in various load conditions to make the engine more efficient.The contrast of different load testing indicates that the fuel consumption rate is reduced by 10%-20%,and the short-time overloading capability of the whole system is increased over 60%.