基于双闭环PID的挖掘机泵扭矩控制策略

发动机与泵扭矩的不匹配所造成发动机转速波动是挖掘机能量浪费的主要原因.分析了发动机与泵稳定工作条件下的扭矩匹配关系,试验研究了泵扭矩调整的影响因素,确定了调整泵吸收扭矩让发动机工作在调速特性曲线的电控节能控制目标,建立了基于PID（Proportion Integration Differentiation）的泵扭矩调整方案并开展了泵扭矩调整试验.试验结果表明：挖掘机液压系统自带压力切断功能可实现无负荷和溢流工况下的节能控制,电控系统仅在泵正常工作范围内通过改变比例阀电流调整泵扭矩,泵扭矩的控制策略在工作初始和工作过程中的调整方法有差异,采用的双闭环PID控制方法能保证发动机稳定在调速特性范围内,这为开发节能效果更好的挖掘机节能控制系统打下基础.

Torque control strategy for double-closed-loop PID-based excavator pumps

As the excavator energy-waste is mainly resulted from the rotary speed fluctuation by torque-mismatching between engine and pump,the torque-matching relationship between pump and engine is analyzed under stable working conditions.Meanwhile,the impact factors of pump torque adjustment are tested.Furthermore,the control target of electric-control energy-saving is determined by adjusting pump absorption torque for engine to work under governing property curve.Upon completion of the PID-based adjustment scheme,the pump torque testing is conducted based on rotary speed sensing.Accordingly,it is indicated from testing results that,the idle and overflow energy-savings are realized using hydraulic system pressure-off function.Only under normal working scope,the torque adjustment is achieved through proportion-valve current adjustment.Due to a difference between initial and working adjustments,the engine can be stabilized among the governing speed scope via double-closed-loop PID-based method.Therefore,this approach paves a venue to develop more energy-saving excavators.