| 主权项 |
1. A sealing assembly comprising:
a bulkhead housing having a portion thereof exposed to a first fluid having a first fluid pressure and having a portion thereof exposed to a second fluid having a second fluid pressure, and having a locating shoulder facing in a generally axial direction; a shaft having a portion thereof exposed to said first fluid and a portion thereof exposed to said second fluid, said shaft defining an externally-oriented sealing surface of generally cylindrical form, at least part of said sealing surface being located at least partially within said bulkhead housing and being relatively movable with respect to said bulkhead housing; a retainer located radially outward of at least a portion of said shaft and surrounding at least a portion of said shaft, said retainer defining a retaining shoulder facing generally toward said locating shoulder of said bulkhead housing, and said locating shoulder facing generally toward said retaining shoulder; a backup ring of generally circular form located between said retaining shoulder and said locating shoulder, and having a first ring end with a first portion thereof facing and adjoining said retaining shoulder and a second ring end having at least a portion thereof facing and adjoining said locating shoulder, said first and second ring ends facing in generally opposite directions, said backup ring having a ring inner surface facing generally inward toward said shaft sealing surface and establishing a region of clearance therewith, and having a ring outer surface facing generally radially outward, said backup ring having radial thickness between said ring inner surface and said ring outer surface, at least a portion of said ring inner surface and at least a portion of said ring outer surface being exposed to said second fluid pressure; said region of clearance forming an extrusion gap between said ring inner surface and said shaft sealing surface at said first ring end; means for sealing establishing (a) a first inner sealing site at said first ring end sealing said extrusion gap between said ring inner surface and said shaft sealing surface, (b) a first outer sealing site at said first ring end sealing between said first ring end and said retainer, (c) a second inner sealing site at said second ring end sealing between said second ring end and said bulkhead housing, and (d) a second outer sealing site at said second ring end sealing between said second ring end and said bulkhead housing, said second inner sealing site and said second outer sealing site encircling said shaft, said second inner sealing site separated from said shaft by a radial distance and said second outer sealing site separated from said shaft by a radial distance, said radial distance separating said second outer sealing site from said shaft being greater than said radial distance separating said second inner sealing site from said shaft; said first inner and outer sealing sites sealing said first fluid pressure from said second fluid pressure and said second inner and outer sealing sites sealing said first fluid pressure from said second fluid pressure, wherein: said first outer sealing site being located generally radially outward from said first inner sealing site and said second outer sealing site being located generally radially outward from said second inner sealing site, said first inner sealing site and said first outer sealing site defining a first hydraulic area exposed to said first fluid pressure, said first fluid pressure acting over said first hydraulic area and producing a first axially-oriented hydraulic force acting on said backup ring in a first hydraulic force direction toward said locating shoulder, said first hydraulic area being an annular area located between said first inner and outer sealing sites, and said second inner sealing site and said second outer sealing site defining a second hydraulic area exposed to said first fluid pressure, said first fluid pressure acting on said second ring end over said second hydraulic area and producing a second axially-oriented hydraulic force acting on said backup ring in a second hydraulic force direction that is opposite to said first hydraulic force direction and toward said retaining shoulder. |
