Turbine wheel for a turbine engine

A turbine wheel for a turbine engine, comprising a disk carrying blades each having a platform, carrying an impeller connected by a stilt to a root. Each blade comprises an upstream radial wall and a downstream radial wall extending inwards from the platform of the blade. The roots of the blades are engaged into slots on the periphery of the disk, so that the radial walls of the blades and the platforms of the blades are circumferentially arranged end-to-end, and define inter-blade cavities radially inside the platforms, each accommodating an inter-blade sealing and vibration damping member. At least one member comprises an elastically deformable element configured so as to be elastically prestressed against the walls of a cavity in the member mounting position.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a turbine wheel for a turbine engine, such as an aircraft jet engine or turboprop provided with such a wheel. It also relates to a sealing and vibration damping member intended to be used with a turbine wheel and a turbine engine, as mentioned above.

2. Description of the Related Art

A wheel10of a high pressure turbine in a turbine engine, as shown inFIG. 1, comprises a disc14carrying blades16regularly distributed around the wheel axis and the roots18of which are engaged into substantially axial slots of the periphery of the disc14. The blade roots18may be of the fir tree or dovetail section type, and the grooves in the disc14have shapes that match those of the blade roots18and define teeth or ribs20between them.

Each blade16comprises an impeller22the radially inner end of which is connected to a platform24, which is itself connected to a root18by a stilt26.

The upstream end and the downstream end of each platform24are respectively connected to an upstream radial wall30extending radially inwards and to a downstream radial wall28extending radially inwards.

In mounting position (FIGS. 1 and 2), the platforms24of the blades16are circumferentially arranged end-to-end so as to form an inner annular wall for the flowing of primary air from a combustion chamber. Similarly, the upstream28and downstream30radial walls are arranged opposite each other on the circumference.

Mounting sealing and vibration damping members32into inter-blade cavities is known. More particularly, each inter-blade cavity is defined radially outwards by the inner faces of two platforms24positioned opposite each other on the periphery, radially inwards by a rib20of the disc14, axially by two transverse upstream30and downstream28radial walls, the ends of which are positioned opposite each other on the periphery, and circumferentially by the stilts26of the blades16.

Each sealing and vibration damping member32is mounted into a cavity and held in position therein by pins34protruding in the cavity. In a first known embodiment (FIG. 2), the upstream radial wall and the downstream radial wall of each blade each comprise a pin34which radially holds the member32inwards, on one side of the stilt26. In another embodiment, each stilt26of a blade comprises a pin34on each one of its side faces.

Such pins34thus form supports for the members upon stopping of the turbine engine and when mounting the members32into the cavities. However, in operation, centrifuge force presses the members32against the platforms24so that the pins34no longer have a holding function.

To reduce the weight of the turbine wheel, omitting the pins34mentioned above would be interesting, while ensuring the holding in position of the members32upon stopping of the turbine engine and an easy mounting of the members32into the cavities.

SUMMARY OF THE INVENTION

The invention more particularly aims at providing a simple, efficient and cost-effective solution to the problems of the prior art disclosed above.

For this purpose, it provides a turbine wheel for a turbine engine, comprising a disk carrying blades each having a platform, carrying an impeller connected by a stilt to a root, with each blade comprising an upstream radial wall and a downstream radial wall extending inwards from the platform of the blade, with the roots of the blades being engaged into slots on the periphery of the disk so that the radial walls of the blades and the platforms of the blades are circumferentially arranged end-to-end, and define inter-blade cavities radially inside the platforms each accommodating an inter-blade sealing and vibration damping member, characterized in that at least one member comprises elastically deformable means which are so configured as to be elastically prestressed against the walls of a cavity in said member mounting position.

According to the invention, at least one sealing and vibration damping member is held in position by elastic means and no longer by pins like in the prior art. The pins can thus be omitted and the weight of the turbine wheel can be reduced. The reduction in weight is particularly important when all the members comprise elastically deformable means as above.

According to another characteristic of the invention, the member comprises a flanged edge extending inwards a bottom wall applied to the inner faces of the platforms, with the flanged edge comprising at least two opposite lugs elastically prestressed against opposite faces in front of a cavity.

Adding elastically deformable lugs onto pre-existing members is very simple and may be executed during a maintenance operation for instance.

In a preferred embodiment of the invention, a first lug radially extends inwards relative to an upstream portion of the flanged edge and a second lug radially extends inwards relative to a downstream portion of the flanged edge.

Advantageously, the first lug and the second lug cover the junction between adjacent upstream radial walls and the junction between two adjacent downstream radial walls, respectively. The first and second lugs thus make it possible to enhance sealing between the upstream and downstream radial walls.

The upstream portion and the downstream portion of the flanged edge of the member preferably each comprise two slots radially opening inwards and respectively formed on either side of the first and second lugs. Such slots give a greater flexibility to the lugs, which reduces stresses.

The invention also relates to a turbine engine, such as turbojet or a turboprop, comprising a turbine having at least one turbine wheel of the type disclosed above.

The invention also relates to a sealing and vibration damping member comprising a bottom wall extending in a flanged edge having two opposite flanks and two end portions which join the flanks and which each carry an elastically deformable lug extending opposite the bottom wall from the flanged edge.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

AsFIGS. 1 and 2have already been described above, reference is now made toFIG. 3which shows a sealing member according to the known technique, intended to be mounted into an inter-blade cavity.

More specifically, each member32comprises a bottom wall36which extends on the whole periphery thereof into a flanged edge38or peripheral edge, which extends substantially radially inwards. The flanged edge38of each member32comprises an upstream portion40and a downstream portion42, as well as two side flanks44which connect the upstream40and downstream42portions. Each sealing and vibration damping member32has an external shape matching that of the faces of the walls which define an inter-blade cavity, so that the sealing member32can come into contact with such faces and provide sealing at the junction between the platforms24and the upstream28and downstream30radial walls.

In the following description relating to the invention, the parts which are similar to those described above have a reference with a number increased by a hundred.

According to the invention, each sealing and vibration damping member132comprises elastically deformable means. As shown inFIG. 4, the upstream portion140of the flanged edge138comprises a first lug146which extends radially inwards from the flanged edge138. The downstream portion142of the flanged edge138comprises a second lug148which extends radially inwards from the flanged edge138.

The upstream portion140of the flanged edge138comprises a slot150on either side of the first lug146. Similarly, the downstream portion142of the flanged edge138comprises a slot152on either side of the first lug148. Such slots150,152give them a greater flexibility. As shown inFIG. 4, each slot150,152comprises a portion with a reduced section154opening in a portion with a larger section156and a substantially circular rounded shape. Such rounded shape156makes it possible to distribute the deformation constraints on the lugs146,148over the whole upstream140or downstream portion of the flanged edge138.

In another embodiment, the slots158may be straight as shown inFIG. 7. It should also be noted that the upstream140and downstream142portions may have no slot, as shown inFIGS. 5 and 6.

To mount each member132into a cavity, the lugs146,148are pressed against each other and the member132is then radially inserted into a cavity until the bottom wall135comes in contact with an inner face of two adjacent platforms. The elastic lugs146,148are so configured as to exert a pressure onto the upstream radial walls130and on the downstream radial walls, in mounting position. Using a member132according to the invention makes it possible to eliminate the holding pins of the prior art.

More specifically, the first lug146is supported by two adjacent upstream radial walls130so as to cover the gap between these. Similarly, the second lug148is supported by two adjacent downstream radial walls so as to cover the gap between these. Such position of the first and second lugs146,148makes it possible to enhance sealing between the upstream and downstream radial walls.