Automatic control device of a labyrinth seal clearance in a turbo-jet engine

Claim 1

A labyrinth seal assembly, comprising: a plurality of rotary annular tip members, a rotor supporting the tip members, an annular wear seal member cooperating with the tip members, an annular carrier supporting the wear seal member rotatable at most at a lower speed than the tip members, the annular carrier having a series of peripherally distributed apertures for receiving cooling air from the air flow controlled by the labyrinth seal assembly, an annular stator member carrying the annular carrier and defining an annular chamber having radially outer inlet orifices for receiving hot air and radially inner outlet orifices at a downstream part thereof for the exhaust of said air, said annular chamber containing an annular thin metallic sheet member provided with a multiplicity of holes and serving to divide the annular chamber into radially inner and radially outer sections, the member being arranged to direct an air flow through the holes therein on to the carrier wherein said cooling air supplied by said apertures of said annular carrier is communicated to said annular chamber and, the overall arrangement being such that the labyrinth seal clearance is maintained constant automatically irrespective of the rating of an associated turbo-machine wherein the carrier and the rotor carrying the tip member have co-operating parts so shaped as to create upstream of the zone containing said tip members and said wear seal a convergent-divergent annular nozzle of annular form defining a primary throat, wherein said peripherally distributed apertures of the annular carrier open into the region of the throat of the convergent-divergent nozzle, thus providing communication between a radially outer section of said annular chamber and said throat of said nozzle.