Underplatform damping members and methods for turbocharger assemblies

1. A damping member comprising:

a body having a shape to fit between (a) a recess that radially extends into an outer surface of a rotor disk of a turbocharger and (b) laterally protruding shoulders of platforms in at least two neighboring blades of the turbocharger, wherein the recess has an axial dimension greater than a circumferential dimension of the recess,

wherein the body is disposed, secured and retained within the recess in the rotor disk along a complete axial dimension of the body and a complete circumferential dimension of the body, wherein the axial dimension of the recess does not extend across an entire thickness dimension of the rotor disk, wherein the circumferential dimension of the recess extends in a circumferential direction under surfaces of the laterally protruding shoulders of the platforms in the neighboring blades of the turbocharger, and

wherein the body sits under the platforms in the neighboring blades, remains in contact with the platforms, provides friction damping between the platforms and the body and thereby dampens vibrations of the blades during rotation of the neighboring blades and the rotor disk by engaging along a line of contact, that extends a complete length of the body, under surfaces of the laterally protruding shoulders of the platforms that oppose the rotor disk of at least one of the neighboring blades.

2. The damping member of claim 1 , wherein the body has the shape to concurrently engage the under surfaces of the shoulders of the platforms of the neighboring blades when the platforms are misaligned with respect to the rotor disk.

3. The damping member of claim 1 , wherein the shape of the body is sized to fit between the recess in the rotor disk and the laterally protruding shoulders of the platforms in the neighboring blades that do not include shanks vertically extending between dovetails of the blades and the platforms of the neighboring blades.

4. The damping member of claim 1 , wherein the body has the shape of a sheet having opposite parallel first and second sides and opposite parallel first and second edges, wherein the first and second edges intersect the first side at curved interfaces that are configured to concurrently engage the under surfaces of the shoulders of the platforms in the neighboring blades, and

wherein the opposite parallel first and second sides are closer to each other than the opposite parallel first and second edges.

5. The damping member of claim 1 , wherein the body has the shape of a wedge comprising a rotor surface configured to engage the rotor disk inside the recess extending into the rotor disk, a first angled surface configured to concurrently engage the under surface of the shoulder of one of the neighboring blades that faces the rotor disk, and a second angled surface configured to concurrently engage the under surface of the shoulder of another one of the neighboring blades that opposes the rotor disk.

6. The damping member of claim 1 , wherein the body has the shape of a tapered pin that is elongated along a length direction and that has a curved surface having a radius of curvature that changes as a function of length along the length direction.

7. The damping member of claim 6 , wherein the curved surface of the body is configured to concurrently engage the under surfaces of the shoulders of the platforms in the neighboring blades.

8. The damping member of claim 1 , wherein the body is formed from a resilient material configured to bend and generate a preload force applied against the under surfaces of the shoulders of the platforms in the neighboring blades.

9. The damping member of claim 1 , wherein the body has the shape of a sheet bent in a U-shape, including opposite outer and inner curved surfaces that are joined by opposite edges.

10. A method comprising:

forming a recess into an outer surface of a rotor disk in a turbocharger, the recess formed into the outer surface in a location that is between laterally protruding shoulders of platforms in at least two neighboring blades of the turbocharger, wherein the recess has an axial dimension greater than a circumferential dimension, wherein the axial dimension of the recess does not extend across an entire thickness dimension of the rotor disk, and wherein the circumferential dimension extends in a circumferential direction under the surfaces of the shoulders of platforms of the neighboring blades of the turbocharger; and

inserting a damping member into the recess in the rotor disk such that the damping member is between the rotor disk and the shoulders of the platforms in the neighboring blades, wherein the recesses in the rotor disk secure and provide retainment of a respective damping member disposed therein along a complete axial dimension of the respective damping member and a complete circumferential dimension of the respective damping member, and wherein the damping member is inserted into the rotor disk and the damping member sits under the platforms in the neighboring blades, remains in contact with the platforms, provides friction damping between the platforms and the damping member and thereby dampens vibrations of the blades during rotation of the neighboring blades and the rotor disk by engaging along a line of contact, that extends a complete length of the damping member, an under surface of the shoulders of the platforms that oppose the rotor disk of at least one of the neighboring blades.

11. The method of claim 10 , wherein forming the recess includes retrofitting the turbocharger that does not include sufficient space to fit the damping member between the rotor disk and the shoulders of the platforms in the neighboring blades by cutting into an exterior surface of the rotor disk to form the recess.

12. The method of claim 10 , wherein inserting the damping member includes positioning the damping member between the rotor disk and the shoulders of the platforms in the neighboring blades that do not include shanks that vertically extend from dovetails of the blades to the platforms of the neighboring blades.

13. The method of claim 10 , wherein inserting the damping member includes positioning the damping member between the rotor disk and the shoulders of the platforms in the neighboring blades such that the damping member concurrently engages the under surfaces of the shoulders that are misaligned with respect to the rotor disk.

14. A turbocharger assembly comprising:

a rotor disk having an exterior curved surface with dovetail slots extending into the rotor disk, the rotor disk also including one or more recesses extending into the exterior curved surface between the dovetail slots, wherein each of the recesses has an axial dimension greater than a circumferential dimension;

plural turbocharger blades having airfoils, platforms having laterally protruding shoulders, and dovetails disposed in the dovetail slots of the rotor disk, wherein the axial dimension of each of the recesses does not extend across an entire thickness dimension of the rotor disk, and wherein the circumferential dimension of each of the recesses extends in a circumferential direction under surfaces of the laterally protruding shoulders of the platforms in pairs of the turbocharger blades; and

damping members disposed in the recesses in the rotor disk between the rotor disk and the shoulders of the platforms in pairs of the turbocharger blades, wherein the recesses in the rotor disk secure and provide retainment of a respective damping member disposed therein along a complete axial dimension of the respective damping member and a complete circumferential dimension of the respective damping member, the damping members configured to sit under the platforms, remain in contact with the platforms, provide friction damping between the platforms and the damping members and thereby dampen vibrations of the turbocharger blades during rotation of the turbocharger blades and the rotor disk by engaging along a line of contact, that extends a complete length of the damping member, an under surface of at least one of the shoulders of the platforms in the pairs of the turbocharger blades.

15. The turbocharger assembly of claim 14 , wherein the damping members have shapes that concurrently engage the under surfaces of the shoulders of the platforms in the pairs of the turbocharger blades even when the under surfaces are misaligned with respect to the rotor disk.

16. The turbocharger assembly of claim 14 , wherein the turbocharger blades do not include shanks that vertically extend from the dovetails to the platforms.

17. The turbocharger assembly of claim 14 , wherein the damping member has a shape of a tapered pin that is elongated along a length direction and that has a curved surface that intersects the rotor surface with a radius of curvature that changes as a function of length along the length direction.

18. The turbocharger assembly of claim 14 , wherein the damping member has a shape of a cylindrical pin that is elongated along a length direction.