摘要
某中型液压挖掘机在使用过程中出现动臂不下落现象,导致整车不能正常使用。排查动臂下降先导控制压力、动臂联阀杆、动臂负载保持阀以及整机液压系统清洁度,将动臂负载保持阀进行试验台测试,发现负载保持阀导级在高压情况下出现开启点后移及卡滞现象。将负载保持阀导级阀套和阀芯进行不同压力下的变形仿真,发现负载保持阀阀套在高压下变形量较大,阀套与阀芯配合间隙变小。动臂无法下落的主要原因是动臂负载保持阀导级配合间隙过小,次要原因是油液清洁度超出主阀使用要求,在液压系统高压力工况下存在阀芯卡滞风险。通过增大负载保持阀导级配合间隙和控制液压系统油液清洁度的方式进行改进,改进后重新验证,动臂不下落现象消失。
A medium-sized hydraulic excavator experienced a malfunction where the boom failed to lower,rendering the equipment inoperable.During troubleshooting,the pilot control pressure for boom descent,boom spool valve,boom load-holding valve,and hydraulic system cleanliness were inspected.Bench testing of the load-holding valve revealed delayed opening and sticking of the pilot stage under high-pressure conditions.Deformation simulations of the pilot valve sleeve and spool under varying pressures demonstrated significant sleeve deformation under high pressure,resulting in reduced clearance between the sleeve and spool.The primary root cause was identified as insufficient clearance in the load-holding valve pilot stage,with secondary contributing factors including hydraulic fluid contamination exceeding main valve specifications,creating spool sticking risks under high-pressure operation.Corrective measures involved optimizing the pilot stage clearance and implementing stricter hydraulic fluid cleanliness controls.Post-modification verification confirmed complete resolution of the boom descent failure,validating the effectiveness of the improvements.
作者
戚振红
孙坚
QI Zhen-hong;SUN Jian(Xuzhou AMCA Hydraulic Technology Co.,Ltd.,Xuzhou 221004,China;Hebei Provincial Key Laboratory of Heavy Machinery Fluid Power Transmission and Control,Yanshan University,Qinhuangdao 066004,China)
出处
《液压气动与密封》
2025年第8期102-106,共5页
Hydraulics Pneumatics & Seals
关键词
挖掘机
动臂下落
负载保持阀
配合间隙
卡滞
excavator
boom lowering
load-holding valve
mating clearance
sticking
