Separable seal assembly for a gas turbine engine

Abstract

A seal assembly for sealing a rotatable shaft in a gas turbine engine, wherein the shaft includes sections of greater shaft diameter located both forward and aft of the seal shaft coupling point is provided. The seal assembly includes a first semi-annular segment with a first end, a second end, and a plurality of seal teeth, where the first and second ends each include an overlap joint. The seal assembly also includes a second semi-annular segment with a first end, a second end, and a plurality of seal teeth, where the first and second ends each include an overlap joint. The first end of the second segment is coupled to the first end of the first segment, and the second end of the second segment is coupled to the second end of the first segment.

What is claimed is: 
     
         1 . A seal assembly for sealing a rotatable shaft in a gas turbine engine comprising:
 The rotatable shaft comprising sections of greater shaft diameter located both forward and aft of the seal shaft coupling point, said seal assembly comprising:   a first semi-annular segment comprising a first end, a second end, and a plurality of seal teeth, said first and second ends each including an overlap joint; and   a second semi-annular segment comprising a first end, a second end, and a plurality of seal teeth, said first and second ends each including an overlap joint, said first end of said second segment being coupled to said first end of said first segment, and said second end of said second segment being coupled to said second end of said first segment.   
     
     
         2 . The seal assembly of  claim 1  further comprising:
 a seal coupled to a first shaft, the seal being separable from the shaft and including at least two segments; 
 the seal being capable of being installed or removed on a complete shaft without a need to provide clearance on either end of the shaft; 
 the at least two segments facilitating installation of the seal on the shaft to include shafts having a greater diameter on both sides of a seal installation point, thereby providing a multiplicity of choices for location of the seal with respect to the shaft. 
 
     
     
         3 . A seal assembly for sealing a rotatable shaft in a gas turbine engine comprising:
 The shaft comprising sections of greater shaft diameter located both forward and aft of the seal shaft coupling point, said seal assembly comprising:   a first half circle-shaped segment and a second half circle-shaped segment;   the first segment including a first end having a connector and a second end having a connector; and,   the second segment including a first end having a connector and a second end having a connector.   
     
     
         4 . The seal assembly of  claim 3  further comprising:
 The first segment and the second segment being assembled by an overlap joint, wherein mating connectors and, are joined with co-mating connectors; and, 
 the overlap joint thereby allowing the seal to carry a hoop load. 
 
     
     
         5 . The seal assembly of  claim 4  further comprising segments, each segment including a plurality of seal teeth. 
     
     
         6 . The seal assembly of  claim 5  further comprising a primary retention for the seal being an interference fit between seal and a shoulder of shaft wherein the first segment includes a shoulder that enables secondary axial and tangential retention on the shaft. 
     
     
         7 . The seal assembly of  claim 6  further comprising the assembly of the first and second segments and about the shaft being accomplished by heating both the first and the second segments to a predetermined temperature, sliding first segment in from a side of shaft, and sliding second segment axially such that the connectors of one segment engage the mating halves of connectors on the other segment, respectively. 
     
     
         8 . The seal assembly of  claim 7  further comprising allowing temperature to equalize within the shaft thereby providing an interference fit being generated between first and second segments and shaft;
 the first and second segments enabling the ring formed by their coupling to carry hoop stress; 
 the first and second segments being secured together by a retaining ring that is expanded into a slot; 
 an alignment pin being placed in an alignment orifice that is disposed between the first and second segments; and, 
 the retaining ring being installed last, thereby securing the alignment pin. 
 
     
     
         9 . A seal assembly for sealing a rotatable shaft in a gas turbine engine comprising:
 the shaft comprising sections of greater shaft diameter located both forward and aft of the seal shaft coupling point; and,   said seal assembly comprising a first inner ring segment, a second inner ring segment, a first outer ring segment, and a second outer ring segment.   
     
     
         10 . The seal assembly of  claim 9  further comprising the first outer ring segment and the second outer ring segment coupled together about first and second inner ring segments and wherein the outer ring segments and each include a plurality of seal teeth. 
     
     
         11 . The seal assembly of  claim 10  further comprising the primary retention of seal being accomplished by an interference fit to shaft, and secondary axial retention being accomplished by protrusions on the inner diameter of seal on either side of a shoulder of shaft. 
     
     
         12 . The seal assembly of  claim 11  further comprising that secondary tangential retention is provided by a tab which engages with a keyway on the shaft;
 The four ring segments are coupled along two 360 degree seams between the segments; and, 
 the segments being coupled by a securing method chosen from the group welding, brazing. 
 
     
     
         13 . The seal assembly of  claim 12  further comprising that an initial assembly of first and second segments and about shaft is accomplished by:
 heating both first and second inner ring segments; 
 sliding first inner ring segment in from the side, and sliding second inner ring segment axially such that connector engages the mating half of connector, while a corresponding set of connectors engages in a similar fashion on the other side of the seal; and, 
 When allowed to equalize in temperature with shaft, an interference fit is generated between first and second inner ring segments and shaft, enabling segments to carry hoop stress. 
 
     
     
         14 . The seal assembly of  claim 13  further comprising that following the initial assembly steps of  claim 13 :
 two 180 degree segments being the first outer ring segment and the second outer ring segment, are coupled to the ring created by first and second inner ring segment; 
 the 180 degree segments being welded in place wherein the weld joint is formed along two 360 degree seams between the outer ring segments, and the inner ring segments; and, 
 Seal teeth are finish machined following assembly and welding of segments thereby ensuring that tooth alignment and tip runout requirements are met. 
 
     
     
         15 . A seal assembly for sealing a rotatable shaft in a gas turbine engine comprising:
 the shaft comprising sections of greater shaft diameter located both forward and aft of the seal shaft coupling point; and,   said seal assembly comprising a plurality of identical segments.   
     
     
         16 . The seal assembly of  claim 15  further comprising the plurality being four identical segments connected to the shaft by a dovetail joint and wherein each segment includes a plurality of seal teeth. 
     
     
         17 . The seal assembly of  claim 16  further comprising that assembly of segments about the shaft is accomplished by:
 inserting the segments through a load slot formed in the shaft; and, 
 rotating the segments around the load slot, repeating until all segments are in place. 
 
     
     
         18 . The seal assembly of  claim 17  further comprising installing a set screw through a tapped hole located in each segment. 
     
     
         19 . The seal assembly of  claim 18  wherein the set screw engages with a dimple in shaft thereby providing secondary retention. 
     
     
         20 . The seal assembly of  claim 15  wherein each segment has formed upon it a dovetail pressure face over a central 50% of its arc length, thereby allowing a corresponding reduction in the size of the load slot.