Labyrinth structure for air outlet of gas turbine engine bearing chamber

Claim 1

In a gas turbine engine including a turbine main shaft, a turbine connected to said main shaft for rotation therewith, a bearing chamber formed around said main shaft in the vicinity of said turbine, means for supplying cold air to said bearing chamber, a gas bearing mounted within said bearing chamber for supporting a high temperature side of said main shaft, and means for controllably exhausting air from said bearing chamber, the improvement wherein said air exhaust means comprise a first plurality of generally concentric annular projections formed on a stationary wall portion of said turbine engine, said first projections being spaced apart radially of said turbine shaft and extending in a direction axially thereof to define annular spaces therebetween, a second plurality of generally concentric annular projections formed on a wall portion of said rotatable turbine, said second projections being spaced apart radially of said turbine main shaft and extending in a direction axially thereof to define annular spaces therebetween, said first and said second projections being arranged in a staggered opposed relationship with each of the projections of one of said plurality of projections extending into the annular spaces formed between the other of said plurality of projections, and a plurality of thin walled annular plates affixed to each of the projections of at least one of said plurality of projections, said plates being located to extend diametrically from the projections to which they are affixed and transversely across said spaces formed between said other plurality of projections, said plates terminating short of engagement with the projections of said other plurality of projections to define a spacing therebetween, said first and said second plurality of projections being located to define a labyrinthine flow path for air exhausting from said bearing chamber, said labyrinthine flow path as defined by said first and second plurality of projections being located between said turbine and said gas bearing.