单向阀阀芯的振动可靠性分析

Vibration reliabilityanalysis of the check valve spool

单向锥阀在液压系统中应用广泛,其振动直接影响整个系统性能.以先导溢流阀的单向锥阀为例,将锥阀简化为质量-阻尼-弹簧系统的振动模型,得到阀芯振动微分方程,求解出其固有频率.结合共振准则,建立了锥阀阀芯的两种工作状态的振动可靠性功能函数.基于此可靠性功能函数,应用蒙特卡洛法对液压阀阀芯振动时的失效概率与变异系数进行估算,并分析了估算的过程,应用Matlab对阀芯的振动可靠性进行仿真,得到了锥阀的可靠度曲线以及变异系数曲线.以其阀芯为例,在满足可靠条件的情况下,当样本量N数值比较小时,数据波动较大,体现结果不明显.而当取样本量为2 500时,拟定阀芯目标可靠度为96%,相应的目标变异系数为0.1.从得到的仿真曲线中可以看出,得到的可靠度、变异系数均与目标值收敛接近,表明样本量取值越大时阀芯的可靠度越接近目标值,所得到的可靠性结果精度也越高.

Poppet valve is commonly used in hydraulic system,and the vibration of poppet valve directly affects working stability of the hydraulic system.Take poppet valve of pilot-operated relief as an example,the vibration differential equation can simplify the conical valve as the system of quality-damping-spring vibration model.Then it can solve out the natural frequency which include non-damped natural frequency and the damped natural frequency.It establishes the vibration reliability functions which include two kinds of working state of the poppet valve spool through combining with the resonance principle.Based on the reliability function,Monte Carlo method was applied to estimate failure probability and variation coefficient when the hydraulic valve spool vibrate,and then it analyzes the process of estimation.It utilizes Matlab to simulate the vibration reliability of the valve spool,and it get the reliability curve and the variation coefficient curve of the poppet valve.Taking the valve spool as an example,when the sample volume Nis small,the range of data fluctuation will get wide,the result is not obvious.While the sample volume is 2 500,the target reliability of the valve spool is 96%and the corresponding variation coefficient is 0.1.From the observation of simulation curves,it shows that the reliability and the variation coefficient close to the target.It shows that the reliability of valve spool will closer to the target when it get the larger sample volume,and then the outcomes of reliability will get the higher precision.