Claims for Patent: 5,503,407

Summary for Patent: 5,503,407

Title:	Windbacks for rotating shafts
Abstract:	An annular windback is provided in a housing containing a lubricant sump and a rotating shaft therein. The windback is located at one end of the sump and the shaft extends through the windback. The housing has a seal interacting between the housing and the shaft to prevent lubricant from exiting the sump and to prevent other media within the housing from entering the sump. The windback is located between the seal and the one end of the sump and has a spiral groove in the inner annular surface facing the shaft for providing a return path for lubricant carried toward the seal by shaft windage. One or more radial holes are formed in the windback at an axial location thereon between the seal and the closer end of the spiral groove to equalize the pressure at the aforesaid axial location between the windback and the shaft with the pressure in the remainder of the sump.
Inventor(s):	McNickle; Alan D. (Sellersville, PA)
Assignee:	Stein Seal Company (Kulpsville, PA)
Application Number:	08/229,172
Patent Claims:	1. A windback means for use with a rotating shaft which has a portion thereof adapted to be disposed in a lubricant containing sump, said windback means comprising an elongated annular member having axially spaced ends and an inner and an outer surface and adapted to receive the shaft therein, said annular member having a flange having two sides with one side of said flange extending radially outwardly from one end of said annular member, said flange having openings for accommodating securing means so that said flange may be secured to a non-moving member such as a housing, which is adapted to receive the shaft and the lubricant-containing sump therein, the other end of said annular member adapted to be positioned closer to said lubricant-containing sump than said one end, the inner surface of said annular member which faces the shaft when assembled therewith, having a spirally extending thread formed therein extending from said other end of said annular member and terminating short of said flange to provide a return path for any lubricant that has been moved by rotation of said shaft from said other end toward said one end of said annular member, and the improvement wherein said annular member has at least one radial opening therein axially located between the terminus of said thread and said flange and extending from said inner surface entirely through said annular member to said outer surface thereof, to increase the pressure on the inner side of said annular member to the pressure level on the outside of the annular member thereby to prevent lubricant from moving along the thread beyond the opening in the direction of said flange and a segmented seal mounted on said flange and positioned to prevent flow along said shaft, said seal being mounted on said flange adjacent said one end of said annular member whereby said opening prevents lubricant from fouling said seal segments. 2. The windback means of claim 1 wherein said at least one opening comprises a plurality of spaced radial openings circumferentially spaced on said annular member with each opening being at an axial location along said annular member between said flange and the terminus of said thread. 3. The windback means of claim 1 wherein said one opening is one of a plurality of openings spaced equidistantly about the circumference of said annular member at said axial position. 4. In combination, a rotating machine having an elongated annular housing and an elongated shaft mounted for rotation therein, said housing having two adjacent interior chambers therein and having said shaft extending into each of said chambers and rotatable therein, one of said chambers comprising a lubricant-containing sump and the other chamber containing a gaseous medium, said shaft when rotated causing lubricant to move axially along the shaft from said sump toward said other chamber, means for arresting and returning said lubricant flow back to said sump, comprising: a windback means located in said sump having an elongated annular section forming inner and outer annular surfaces and axially spaced ends, said annular section receiving said shaft adjacent the inner surface thereof at an axial location along said shaft within said sump and adjacent said other housing chamber, the outer surface of said annular section being spaced from said housing and being exposed to the same pressure as the pressure in said sump, said annular section having a flange formed thereon extending radially outwardly from the one end thereof located closer to said other chamber, means fixedly and sealingly mounting said flange to said housing to prevent lubricant from exiting said sump into said other housing chamber along said flange, said inner surface of said annular section having a spiral thread formed therein starting at the other end thereof and extending toward yet terminating short of said one end thereof to form a return path for lubricant carried along said shaft toward said other chamber by the rotation of said shaft, said flange having one of its sides exposed to said other chamber and separating said one chamber from said other chamber except for the annular space between said shaft and the inner surface of said annular section, sealing means mounted on said shaft for sealing said annular space located adjacent said one side of said flange to isolate said chambers from each other, said sealing means comprising a segmented seal ring surrounding said shaft, means biasing each of said seal ring segments into sealing engagement with said shaft, said sealing means including a secondary sealing surface on each of said segments facing a portion of said one side of said flange, means biasing said secondary sealing surface on each of said segments into sealing engagement with said portion of said one side of said flange to form a secondary seal, and said annular segment having at least one radial opening extending therethrough and axially located on said segment between the terminus of said thread and said flange to accommodate lubricant flow from said sump through said opening to said thread terminus and along said thread to increase the pressure on the inner surface of the annular portion to the same pressure as that on the outer surface thereof, thereby to prevent lubricant from said sump from moving along said shaft beyond said radial opening toward said sealing means and into said other chamber to avoid the possibility of fouling the seal ring segments by lubricant. 5. The machine of claim 4 wherein said at least one radial opening comprises a plurality of circumferentially spaced radial openings which are at essentially the same axial location on said annular member.