Retaining device for axially retaining a rotor disk flange in a turbomachine

1. A device for axially retaining a flange of a rotor disk, the device comprising:

a rotor disk having a radial face that presents an annular recess defined by a plurality of walls, one of which is formed by the internal face of a rim that extends radially outwards;

an annular flange presenting, in its radially inner portion, an annular base pressing against the radially outer wall of the recess, and a root that extends from the base radially inwards into the recess of the disk; and

a split annular retaining ring disposed in the recess of the rotor disk, the ring having an axially external face that bears against an axially internal face of the rim, thereby resulting in a first axial force acting in a substantially axial direction, an axially internal face that bears against an axially external face of the root, thereby resulting in a second axial force acting in a direction that is substantially axial and opposite to the first axial force, the axial forces being radially offset relative to each other, and a radially outer face that bears against a radially inner face of the base of the flange, thereby resulting in a radial force acting in a substantially radial direction;

wherein the radially outer face of the retaining ring presents an annular setback such that the radial force that results from said face bearing against the radially inner face of the base of the flange is situated in a plane that is offset axially relative to a radial plane passing through the center of gravity of the retaining ring so as to obtain mechanical equilibrium between the forces acting on said retaining ring; and

wherein said split annular retaining ring presents a right section that is substantially rectangular.

2. A device according to claim 1 , wherein the radial force that results from the radially outer face of the retaining ring bearing against the radially inner face of the base of the flange lies in a radial plane that is located between the axially external and internal faces of the retaining ring.

3. A device according to claim 1 , wherein the annular setback in the radially outer face of the retaining ring is disposed in such a manner that the radial force lies in a plane that is radially offset towards the internal face of the ring relative to the radial plane passing through the center of gravity of the ring when the second axial force that results from the axially internal face of the ring bearing against the axially external face of the root is offset radially outwards relative to the first axial force that results from the axially external face of the ring bearing against the axially internal face of the rim.

4. A device according to claim 1 , wherein a radially inner portion of the retaining ring is received in a groove formed behind the rim of the rotor disk.

5. A turbomachine turbine including at least one retention device according to claim 1 .

6. A turbomachine including at least one retention device according to claim 1 .

7. A device according to claim 1 , wherein the annular setback of the retaining ring communicates with the axially external face of the retaining ring.

8. A device according to claim 7 , wherein said annular setback is configured to receive a feeler after assembly of said retaining ring in order to check if the retaining ring is properly positioned.