电磁阀密封泄漏率模型与计算

Electromagnetic Valve Seal Leak Rate Model Calculation

该文介绍一种常闭式电磁开关阀门,采用圆弧型面的金属阀芯与PTFE光滑平面阀座,形成线接触密封型式,表征实际金属阀芯粗糙峰特征,建立泄漏通道几何模型,利用有限元分析方法确定泄漏率与粗糙度等级及粗糙峰特征的定量关系。对表征的金属阀芯粗糙峰与光滑阀板进行有限元接触分析,得出接触变形后泄漏通道。假设只存在涡旋形泄漏通道,以粘滞-分子流态泄漏,得出了初始密封泄漏率的计算结果。采用有限元方法避免了利用统计学对表面进行复杂数学处理,通过对电磁截止氦质谱仪检测表明,阀门泄漏率计算结果与测试结果具有较好吻合性,同时发现粗糙峰特征对PTFE光滑阀板容易形成应力集中,粗糙峰形貌特征对阀门密封性能具有重要影响。

This article introduces a normally closed electromagnetic valve, which adopts the line contact seal mode between the circular-surface metal spool and the smooth PTFE valve plane seat. The actual roughness characteristic of the metal spool is represented. A geometry model of the leak path is established. And the quantitative relations of the leakage rate between with the roughness class and the roughness characteristic is determined by FEA method. Through the contact analysis of the metal spool and the smooth PTFE plate, the leak path after contact deformation is obtained. Assuming that there is only volute leak path, the initial leak rate of the valve is calculated under the pattern of viscous-molecular flow state leakage. The FEA contact analysis avoids the complex mathematical processing to characterize the surface by traditional statistics. According to the helium leak detection, the calculation results of the valve leakage rate coincide with the testing results. Meanwhile, the stress concentration on the smooth PTFE valve plane produced by the roughness peak is observed. It is concluded that the roughness characteristic has an important effect on the sealing property of valves.