Abstract: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,precompressed magnitude of Oring) 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 selfsealing property with the increase of medium pressure.Both the the maximum contact pressure on main sealing surface and the maximum Mises stress of Oring 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.