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本文介绍在液压挖掘机中采用中开式负载传感系统的工作原理和特性计算。分析表明,这种系统能适应挖掘机复杂的作业工况,具有恒力矩恒压调节和旁路流量控制的功能,能量损失小,功率分配合理。系统中装有射流传感器和反馈控制阀,在换向阀处于中位时,使变量泵的排量降到最小限值,减少环流损失。微动操作时,使液压泵的排量与换向阀操纵杆的行程相对应,从而与液动机运动速度所需要流量匹配,减少旁路流量损失。通过控制进入变量泵伺服调节器的调节压力,实现系统压力补偿和流量补偿,提高系统总效率,节能效果显著。同时,改善了发动机的起动性能和工作机构作业时的平稳性。
This paper describes the working principle and characteristic calculation of a mid-open load sensing system in a hydraulic excavator. The analysis shows that this system can adapt to the complex working conditions of the excavator, and has the functions of constant torque constant pressure regulation and bypass flow control, low energy loss, and reasonable power distribution. The system is equipped with a jet sensor and a feedback control valve. When the reversing valve is in the neutral position, the displacement of the variable displacement pump is reduced to the minimum limit to reduce the circulation loss. In the jog operation, the displacement of the hydraulic pump corresponds to the stroke of the reversing valve lever, so as to match the required flow rate of the fluid movement speed, and to reduce the bypass flow loss. By controlling the regulating pressure into the variable-servo servo regulator, system pressure compensation and flow compensation are achieved, and the overall system efficiency is improved, resulting in significant energy savings. At the same time, the starting performance of the engine and the smoothness of the working mechanism during operation are improved.