High-pressure film-riding seals for rotating shafts

A circumferential seal system especially useful in a fluid environment positioned in a housing for sealing along a rotating shaft rotatable in said housing,

• said housing having two fixed annular housing flanges therein receiving said shaft in the openings thereof respectively and axially spaced along said shaft, said shaft having an outer circumferential surface thereon extending through the openings in said spaced flanges, the first of said flanges being exposed on the radial side thereof that is remote from the second of said flanges to a first housing region of higher pressure, and the second of said flanges having the radially extending surface thereof remote from said first flange exposed to a second housing region of relatively lower pressure,
• said seal system being positioned between two confronting radial surfaces of said housing flanges to limit the fluid flow along said shaft from said first housing region to said second housing region, said sealing system including at least two tandemly spaced sealing devices of generally annular configuration positioned to receive said shaft in the central openings thereof respectively and located between said two confronting radial surfaces, one of said sealing devices comprising a segmented seal ring located adjacent said confronting surface of said first flange and formed from a material having adequate abradability, low density, low weight, and adequate lubricity, said segmented seal ring having a bore surface on the inner circumference of each segment, said segments being mounted to be movable radially toward and away from said shaft circumferential surface to form a primary seal and shaped to prevent leakage between adjacent segments, the second of said sealing devices comprising a floating load ring positioned between the confronting surface on said second flange and said segmented seal ring and mounted to float within limits in the space defined by said housing, said second flange, said segmented seal ring, and said shaft circumferential surface, said load ring having a radial surface thereon positioned to engage a radial surface on each segment of said segmented seal ring to form a secondary seal,
• said load ring having a radial sealing surface thereon, positioned to engage said confronting surface of said second flange to form an ancillary seal therebetween, and having its inner circumferential surface positioned to closely receive said shaft circumferential surface, an anti-rotation device extending from said housing to engage said load ring to prevent rotation of said load ring relative to said housing,
• first springs compressed between said confronting surface of said first flange and the adjacent radial surface of each segment of said seal ring to bias said segments away from said confronting surface of said first flange into engagement with said adjacent radial surface of said floating load ring to effect the secondary seal therebetween and moving the latter axially toward said confronting surface of said second flange, so that the radial surface of said load ring engages said last-mentioned confronting surface to effect said ancillary seal,
• a garter spring mounted on the outer circumferential surfaces of said seal ring segments to move said segments toward said outer circumferential shaft surface, with the bore surface of each of said segments movable to engage said shaft circumferential surface, said flange and said housing being shaped to expose the outer circumferential surfaces of said segmented seal ring and said load ring, and the radial surface of said segmented seal ring being located adjacent said confronting surface of said first flange to higher pressure in said first housing region,
• said bore surfaces on said seal ring segments each having a bearing region and an adjacent lift region thereon in tandem in the axial direction along said shaft, extending from said first housing region toward said second housing region, said bearing region being located adjacent said first housing region and said lift region being located downstream thereof in the direction of axial fluid flow, said seal ring segments having an essentially continuous circumferential sealing dam thereon located on said bore surface adjacent the downstream edge of said segments, said segments forming a circumferential groove disposed on the bore surfaces of said segments and located adjacent to said sealing dam on the upstream side thereof, said seal ring segments each having a plurality of feed grooves formed therein, extending from the side thereof exposed to high pressure fluid to pass such fluid into said circumferential groove,
• and at least one of said shaft outer circumferential surface and of said surfaces of said bearing regions of all of said seal ring segments having at least one shallow circumferentially extending lift pocket formed therein and positioned therein in alignment with the other of said surfaces, said one surface having an axially extending feed groove formed therein, communicating with each of said lift pockets and extending from each of said lift pockets to said high pressure region of said housing to feed high pressure fluid to each of said lift pockets to minimize contact between said bearing region of said segments and said shaft and to increase the life of said seal system.