Rotary fluid-sealing structure using speed-reduction stages

摘要

The present invention provides for a rotary fluid-sealing structure for a harsh environment which reduces the PV pressure (xvelocity) that a sealing system may be exposed through the use of a rotary speed reducing planetary gear system. The system may have multiple stages with the amount of velocity reduction produced by the system being determined by the number of stages and the planetary gear ratios. Several alternatives are presented for the sealing under extreme conditions such as found in the interface between a wash-pipe and a rotary drilling string in a drilling rig.