柱塞泵是工程机械液压系统的动力源和关键元件，其运行状态与服役性能直接 影响着工程机械的施工质量和运营安全。本研究针对柱塞泵工作条件恶劣、常处于变载 荷工况的特点，基于柱塞泵的虚拟样机模型，对其不同负载、不同程度滑靴松动故障状 态的动力学行为进行了仿真分析，提出了一种变载荷工况故障诊断方法。该方法首先采 集柱塞泵的轴向振动信号，然后将振动信号划分成若干相等的分段信号，再计算分段信 号的均方根值，最后基于均方根值趋势线的梯度检测滑靴松动故障。试验结果表明，该 方法可以进行工程机械柱塞泵变载荷工况下滑靴松动故障的有效检测。

Piston pump is the power source and key component of hydraulic system in construction machinery． Its working status and service performance directly affect the construction quality and operation safety of the construction machinery． Aiming at the harsh working environment and the variable load working condition of the piston pump，different severity levels of loose slipper faults were simulated based on the virtual prototype model of piston pump． The dynamic responses of the piston pump under different loading and structural health conditions were investigated through simulated analysis． And a fault diagnosis method of piston pump in construction machinery under variable load condition was proposed in this paper． According to the method，the axial vibration signal of piston pump is collected at first． Then the vibration signal is divided into several equal parts and the ＲMS of each segmented signal is calculated． At last，the loose slipper failure can be detected based on the gradient of the ＲMS trend line． The experimental results show that the proposed method can effectively detect the loose slipper of piston pump in construction machinery under variable load working condition．