Patent ID: 7758051
Filing Date: 2010-07-20
Classification: F16J

Abstract:
1. A gas seal assembly comprising: a pair of mutually rotatable sealing members each of which has a front face adjacent a gap between the two members which constitutes a leakage path through the seal assembly, the members being urged, in use, in a direction to close the gap, and a gas bleed arrangement for allowing gas from a high pressure side of the seal to bleed into the gap so as to apply a force tending to separate the members, the gas bleed arrangement comprising: a bore extending between the front face and a rear face of one of the sealing members, a generally radial groove formed in the rear face of the sealing member, a plate overlying the rear face to cover the groove and thereby define between the rear face of the sealing member and the plate a bleed passage connecting the bore to a high pressure side of the seal, and spring means to urge the plate into sealing contact with the rear face of said one of the sealing members, wherein the plate is formed as a shim that is sufficiently flexible to be deflected by the gas pressure into mating contact with the rear face of the sealing member so as to confine the gas flow of the bleed passage to the radial groove, and the spring means being sufficient to maintain the plate in sealing contact with the rear face of the sealing member at low pressure, the sealing member formed with a grooved rear face is associated with a rotatable shaft and the second sealing member is associated with a stationary casing, and said second sealing member is spring loaded to urge it in a direction tending to close the gap.