Patent ID: 8888104

Claim:
An intershaft seal system disposed between an outer shaft and an inner shaft which are concentric and separately rotatable comprising: (a) a forward mating ring adjacent to a high pressure region; and (b) an aft mating ring adjacent to a low pressure region, said forward mating ring and said aft mating ring separately disposed about and separately rotatable from a piston ring, said forward mating ring and said aft mating ring each having a plurality of divergent flow grooves thereon, each said divergent flow groove includes a pair of grooves which intersect at an apex, said piston ring includes a plurality of substantially vertical channels, each said substantially vertical channel directly communicates at one end with an outer diameter surface of said piston ring and directly communicates at another end with a substantially horizontal channel, each said substantially horizontal channel is communicable with one said apex along said forward mating ring and one said apex along said aft mating ring, said outer diameter surface includes at least one outer groove directly contacting a dam, a fluid from said high pressure region directed through each said substantially vertical channel into said substantially horizontal channel and then onto said apexes as said piston ring rotates with respect to said divergent flow grooves, each said apex directs said fluid into said pair of grooves, said divergent flow grooves produce a substantially symmetric fluid pressure along a forward face and an aft face of said piston ring so as to minimize twist along said piston ring.