US 5,174,584 AGranted

Fluid bearing face seal for gas turbine engines

AssigneeGeneral Electric Company

InventorKenneth A. Lahrman

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Abstract

To restrict fluid flow between a high pressure working gas region and a low pressure lubricating oil sump in a gas turbine engine, a fluid bearing face seal includes a rotating mating ring confronted by a non-rotating carbon sealing ring with a face machined to provide an annular array of alternating lands and liftoff force-generating hydrodynamic lift pads, each comprising a three-step stairwell radially inwardly and outwardly bound by rails flush with the lands. An improved secondary seal includes a carbon mating ring to reduce seating drag forces on a piston ring biased into sealing engagement with a sealing ring carrier and a plurality of fluid orifices for pressure moment balancing the piston ring to the working gas pressure. To generate additional liftoff forces at low mating ring angularly velocities, the sealing ring face may also include an annular hydrostatic lift pad.

Claims14

Dependent claims

A fluid bearing face seal for restricting fluid flow between fluid regions of differing pressures in a gas turbine engine, said seal comprising, in combination:

A. a non-rotating housing 44 member:
B. a mating ring 10 mounted by a rotating shaft of the engine, said mating ring having a first seal face:
C. a carrier 42 supported by said housing member in concentric relation with said mating ring for limited movement relative to said first seal face:
D. a carbon sealing ring 12 for withstanding pressure differentials of at least 150 psi mounted by said carrier and having a second seal face confronting said first seal face to define a seal gap therebetween during operation of the turbine, said second seal face having a distributed annular array of lift pads formed therein, each said lift pad including a stairwell having at least two steps radially bounded by a pair of rails;
and
E. closing spring means acting in opposition to liftoff forces generated by said lift pads and the gas bearing film pressure existing between said first and second seal faces during rotation of said mating ring to actively control the width of said seal gap.
F. a carbon secondary seal for withstanding pressure differentials of at least 150 psi and for restricting fluid flow between said housing member and said carrier, said secondary seal including a carbon piston ring spring biased into seating engagement with a sleeve portion of said carrier and a carbon high lubricity ring mounted in juxtaposition with said piston ring by said housing to reduce seating drag forces on said piston ring.

4 more elements

A fluid bearing face seal for restricting fluid flow between fluid regions of relatively high and low pressures in a gas turbine engine, said seal comprising, in combination:

A. a non-rotating housing member;
B. a mating ring mounted by a rotating shaft of the engine, said mating ring having a first seal face;
C. a carrier supported by said housing member in concentric relation with said mating ring for limited movement relative to said first seal face;
D. a carbon sealing ring mounted by said carrier and having a second seal face confronting said first seal face to define a seal gap therebetween during operation of the turbine said second seal face having a distributed annular array of hydrodynamic lift pads formed therein adjacent the high fluid pressure region and an annular hydrostatic lift pad adjacent the low fluid pressure region;
and
E. closing spring means acting in opposition to liftoff forces generated by said hydrodynamic and hydrostatic lift pads and the gas bearing film pressure existing between said first and second seal faces during rotation of said mating ring to actively control the width of said seal gap.
F. a carbon secondary seal for withstanding pressure differentials of at least 150 psi and for restricting fluid flow between said housing member and said carrier, said secondary seal including a carbon piston ring spring biased into seating engagement with a sleeve portion of said carrier and a carrier high lubricity ring mounted in juxtaposition with said piston ring by said housing to reduce seating drag forces on said piston ring.

4 more elements

Dependencies are inferred from the claim text.