CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of French Patent Application No. 1902777, filed on Mar. 18, 2019, the contents of which is incorporated by reference herein.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to an assembly for a turbomachine, such as, for instance, an aircraft turbojet engine or a turboprop engine.

PRIOR ART

A turbomachine conventionally comprises, in the downstream direction with respect to the direction of gas flow within the turbomachine, a blower, a low-pressure compressor, a high-pressure compressor, a combustion chamber, a high-pressure turbine, a low-pressure turbine, and an exhaust nozzle.

The low-pressure turbine has a plurality of bladed impellers mounted on a rotor shaft, called the low-pressure shaft or low-pressure turbine shaft, which is hollow and extends upstream to the blower, whereby the rotation of the shaft caused by the low-pressure turbine causes the blower to rotate.

The turbomachine also includes certain components that must be lubricated by oil injection, such as rolling bearings that support the low-pressure shaft in rotation. These components are also permanently cooled by a flow of gas which is charged with oil as it flows through the components. To discharge this oily gas stream, the turbomachine includes a vent tube1, also commonly referred to as a “CVT” tube, extending coaxially inside the low-pressure turbine shaft2, as shown inFIGS. 1 and 2. This tube1operates as an outlet for the oily gases, and prevents these gases from coming into contact with the low-pressure turbine shaft2, whose high temperature would cause the oil in the gas flow to coke and the turbomachine to deteriorate.

The vent tube1has a radially inner annular part3from which centering annular parts4extend radially outwards. Each centering part4comprising a groove5opening radially outwards, in which an annular seal6capable of ensuring sealing between the centering part4and the inner surface7of the low-pressure turbine shaft2is mounted.

The vent pipe1can be made in two parts, namely an upstream part1aand a downstream part1b, the downstream end of the upstream part1abeing mounted in the upstream end of the downstream part1b. The downstream end of the upstream part1aof the vent tube1then also has a centering part4comprising a groove5equipped with a seal6capable of ensuring sealing with the internal surface8of the downstream part1bof the vent tube1.

When mounting each part1a,1bof the vent pipe1into the low-pressure turbine shaft2, the centering parts4tend to damage, in particular, the paint layer on the inner surface7of the low-pressure turbine shaft2. As the paint layer provides protection against corrosion, such damage affects the service life of the shaft2.

In order to limit such damage, tools can be provided to improve the positioning of the vent tube1when it is inserted axially into the low-pressure turbine shaft2. In view of the manufacturing and assembly tolerances of the tools and the very small clearances required for assembly between the vent tube1and the low-pressure turbine shaft2, it is in reality not possible to completely avoid such damage.

DISCLOSURE OF THE INVENTION

The invention aims to remedy such drawback in a simple, reliable and inexpensive way.

For this purpose, the invention relates to an assembly comprising a vent tube intended to be mounted inside a turbine shaft of a turbomachine, comprising a radially inner annular part from which at least one annular centering part extends radially outwards, said centering part comprising a groove, characterised in that the assembly comprises a sealing member comprising a sealing part mounted in the groove of the centering part, the sealing part being intended to bear sealingly against an inner surface of the turbine shaft, the sealing member further comprising a protective part covering one area of the centering part located upstream and/or downstream of the groove. The terms upstream and downstream are defined relative to the gas flow through the vent tube and the turbomachine. Besides, the terms axial, radial and circumferential are defined relative to the axis of the vent tube, which coincides with the axis of the turbomachine.

The protective part prevents damage to the turbine shaft when inserting the vent tube by covering the areas of the centering part which may protrude and damage the inner surface of the turbine shaft during assembling operations. The areas to be covered may depend, among other things, on the direction of mounting. It is necessary to cover the area of the centering part which will be exposed first when the vent tube is mounted axially in the turbine shaft.

The protective part and the sealing part can be formed in one piece.

Such characteristic makes it possible to facilitate the assembling of the sealing member on the vent tube.

The protective part can be formed by a ring separate from the sealing part. The sealing part can be formed by an annular seal. The ring forming the protective part can be housed in a housing which is complementary in shape to the centering part.

The protective part and the sealing part can be made of the same or different material(s). In particular, the sealing part can be made of a material with a lower hardness than the protective part.

The sealing element may comprise an upstream protective part covering an area of the centering part located upstream of the groove and a downstream protective part covering an area of the centering part located downstream of the groove.

The protective part of the sealing member may have an upstream end and/or a downstream end comprising at least one hook engaging in a recessed area of the upstream end and/or in a recessed area of the downstream end of the centering part.

The protective part of the sealing member may comprise a cylindrical part connecting the sealing part to the end fitted with the hook.

The sealing part may have an annular bead protruding radially outwards from the cylindrical part. The connecting area between the hook and the cylindrical part may have a rounded shape.

The radius of curvature is, for example, between 0.5 and 3 times the diameter of said cylindrical part, e.g. between 0.05 and 2 mm.

The hook may be annular and may have a truncated conical part suitable for resting against a truncated conical surface of the recessed area.

The invention furthermore concerns a turbomachine comprising a turbine shaft and an assembly of the above-mentioned type mounted in the turbine shaft.

The turbine is for example a low pressure turbine.

