Patent ID: 8967627
Filing Date: 2015-03-03
Classification: F01D,F02C,F16J

Abstract:
1. An intershaft seal assembly comprising: an intershaft seal; and an inner coaxial shaft and an outer coaxial shaft which rotate relative to each other, the intershaft seal being located in an annular space between the inner coaxial shaft and the outer coaxial shaft and maintaining an axial pressure differential between a fluid pressure on a first side of the intershaft seal assembly and a fluid pressure on an opposite, second side of the intershaft seal assembly, the intershaft seal comprising: a sealing ring which is coaxial with the inner coaxial shaft and the outer coaxial shaft, the sealing ring having a first end face and a second end face, the first end face and the second end face being axially spaced from one another; and a first runner and a second runner, which project outwardly from and extend circumferentially around the inner coaxial shaft and which sandwich the sealing ring therebetween, the first runner forming a first annular sealing interface with an inboard portion of the first end face of the sealing ring and the second runner forming a second annular sealing interface with the second end face of the sealing ring, an outer edge of each of the first annular sealing interface and the second annular sealing interface being at the fluid pressure of the fluid on the first side and the second side, respectively, of the intershaft seal assembly, wherein the outer coaxial shaft is stepped to define a first inwardly facing surface and a second inwardly facing surface spaced from the first inwardly facing surface and having a larger diameter than the first inwardly facing surface, the first end face of the sealing ring is stepped such that the inboard portion of the first end face is axially spaced from an outboard portion of the first end face, the outboard portion being outboard of the inboard portion, the inboard portion and the outboard portion have a first outwardly facing surface therebetween, the outboard portion of the first end face and the second face have a second outwardly facing surface therebetween having a larger diameter than the first outwardly facing surface, one or more fluid passages extend from the second end face to the outboard portion of the first end face to produce a fluid pressure on the outboard portion of the first end face which is equal to the fluid pressure on the second side of the intershaft seal assembly, and sealing contact of the sealing ring with the outer coaxial shaft is formed at the first outwardly facing surface to maintain the fluid pressure differential between the fluid pressure on the outboard portion of the first end face and the fluid pressure on the first side of the intershaft seal assembly.