双三角滑环式组合密封的密封性能分析

Sealing Performance Analysis of Double Triangle Slip Ring Combination Seal

针对新型井下排水泵驱动气缸活塞中使用的双三角滑环式密封圈,建立其二维轴对称与三维实体有限元模型。采用二维轴对称模型分析滑环的最小厚度、圆弧半径、宽度与O形圈预压缩量等几何参数和介质压力、往复运动速度、环境温度等工作参数对其静密封和往复动密封性能的影响。采用三维实体模型分析环向接触应力分布和活塞径向偏心对密封性能的影响。结果表明:在静密封中,除滑环宽度外的几何参数会对主密封面的接触应力大小和分布产生较大影响;介质压力增加时,密封圈具有较好的自封性;环境温度的增加会降低最大接触应力与O形圈的最大Mises应力;在动密封中,最大接触应力随时间呈波动变化,介质压力、运动速度与环境温度在一定范围内会影响其密封性能;当活塞处于径向偏心运动状态时,密封性能会随着偏心量的增大而明显降低,故应采取措施尽量提高活塞在气缸中的同轴度。

2D axisymmetric model and 3D finite element model of double trigonometric slip combined seal ring used for the piston of driving cylinder in new downhole drainage pump were established.Based on the established 2D axisymmetric model,the effects of geometric parameters(minimum thickness of the slip ring,arc radius and width,pre-compressed magnitude of O-ring)and working parameters(medium pressure,reciprocating velocity,environment temperature)on the static seal and reciprocating sealing properties were investigated.Based on 3D finite element model,the influence of circumferential contact stress distribution and radial eccentricity of piston on the sealing performance was analyzed.Results show that under static sealing condition,all geometric parameters except slip ring width bring big impact to the intensity and distribution of contact stress applied on main sealing surface.The seal ring has an increasing self-sealing property with the increase of medium pressure.Both the the maximum contact pressure on main sealing surface and the maximum Mises stress of O-ring are decreased with the increase of environment temperature.Under the condition of reciprocating seal,the maximum contact stress is in fluctuation variation,and the medium pressure,moving velocity and environment temperature affect the reciprocating seal property to certain extent.When the piston is in radial eccentric motion,the sealing property is significantly decreased with the increase of eccentric magnitude,therefore measures should be taken to increase the coaxiality of piston in cylinder.