Rotor assembly for electric motor of turbomachine with carbon-carbon composite magnet-retaining jacket member

1. A rotor assembly for an electric motor of a turbomachine that defines an axis of rotation comprising:

a jacket member that is hollow and that defines an inner radial surface facing inwardly toward the axis of rotation;

a magnet member that is received within the jacket member, the magnet member including an outer radial surface facing outwardly from the axis of rotation;

the jacket member made of a sintered composite material having carbon filament and a sintered matrix;

the inner radial surface of the jacket member abutting against the outer radial surface of the magnet member to retain the magnet member in a radial position relative to the axis; and

wherein the sintered composite material is a carbon-carbon composite material.

2. The rotor assembly of claim 1 , wherein the jacket member has a first end and a second end and an axial length measured between the first end and the second end;

wherein the inner radial surface has a radius that is continuously constant for a majority of the axial length of the jacket member.

3. The rotor assembly of claim 1 , wherein the inner radial surface defines an inner radius, wherein the outer radial surface defines an outer radius, and wherein the inner radius is less than the outer radius to define a radial interference fit between the jacket member and the magnet member.

4. The rotor assembly of claim 1 , further comprising an inner member that is received within the jacket member;

wherein the magnet member is disposed radially between the jacket member and the inner member with the jacket member and the inner member cooperatively applying a radial compression load to the magnet member.

5. The rotor assembly of claim 1 , further comprising a projecting end that is partly received within the jacket member and that projects axially away from the jacket member;

wherein the projecting end abuts axially against the magnet member; and

wherein the first projecting end and the second projecting end include respective outer diameter surfaces that are flush and even with the outer radial surface of the magnet member and that abut against the inner radial surface of the jacket member.

6. The rotor assembly of claim 1 , further comprising a first projecting end, a first spacer, a second projecting end, and a second spacer that are received within the jacket member;

wherein the first spacer is disposed axially between the first projecting end and the magnet member;

wherein the second spacer is disposed axially between the second projecting end and the magnet member;

wherein the first projecting end and the second projecting end project axially from the jacket member; and

wherein the first projecting end, the first spacer, the second spacer, and the second projecting end include respective outer diameter surfaces that are flush and even with the outer radial surface of the magnet member and that abut against the inner radial surface of the jacket member.

7. The rotor assembly of claim 1 , wherein the jacket member has a first end, a second end, and an axial length measured between the first end and the second end;

wherein the jacket member is cylindrical and hollow;

wherein the jacket member includes an outer surface;

wherein the jacket member defines a wall thickness measured between the inner radial surface and the outer surface; and

wherein the wall thickness is constant along a majority of the axial length.

8. The rotor assembly of claim 1 , wherein the jacket member is received within a motor stator member of the electric motor for rotation within the motor stator member.

9. A method of manufacturing a rotor assembly for an electric motor of a turbomachine that defines an axis of rotation comprising:

providing a magnet member with an outer radial surface facing outwardly from the axis of rotation;

forming a jacket member from a sintered composite material having carbon filament and a sintered matrix, including sintering the composite material to form a carbon-carbon composite material of the jacket member, the jacket member being hollow and defining an inner radial surface facing inwardly toward the axis of rotation; and

retaining the magnet member within the jacket member with the inner radial surface abutting the outer radial surface to retain the magnet member in a radial position relative to the axis.

10. The method of claim 9 , wherein forming the jacket member includes laying up the carbon filament and an un-sintered matrix material into a pre-sintered composite structure; and

sintering the pre-sintered composite structure to form the sintered composite material.

11. The method of claim 10 , further comprising laying up the carbon filament and the un-sintered matrix material to form the pre-sintered composite structure over the magnet member; and

wherein sintering the pre-sintered composite structure includes sintering the pre-sintered composite structure while over the magnet member.

12. The method of claim 10 , further comprising laying up the carbon filament and the un-sintered matrix material to form the pre-sintered composite structure over a mandrel; and

wherein sintering the pre-sintered composite structure includes sintering the pre-sintered composite structure while over the mandrel.

13. The method of claim 10 , wherein forming the jacket member includes laying up at least one segment of the precure filament in the axial direction along the axis.

14. The method of claim 9 , further comprising providing the magnet member axially between a first projecting end and a second projecting end; and

further comprising retaining the magnet member and the first and second projecting ends within the jacket member with the first and second projecting ends partly projecting from the jacket member.

15. The method of claim 14 , further comprising creating respective outer diameter surfaces of the first projecting end and the second projecting end that are flush and even with the outer radial surface of the magnet member.

16. A turbomachine comprising:

a housing;

a rotating group supported for rotation within the housing about an axis of rotation, the rotating group including a shaft, a wheel mounted on the shaft, and a rotor assembly mounted on the shaft;

an electric motor configured to drive the rotating group in rotation about the axis of rotation;

wherein the rotor assembly comprises:

a jacket member that is hollow and that defines an inner radial surface facing inwardly toward the axis of rotation, the jacket member having a first end, a second end, and an axial length measured between the first end and the second end, the inner radial surface having an inner radius that is continuously constant for a majority of the axial length of the jacket member;

a magnet member that is received within the jacket member, the magnet member including an outer radial surface facing outwardly from the axis of rotation;

an inner member that is received within the jacket member, the inner member including an outer core surface that remains substantially constant along an axial length of the inner member, the magnet member being disposed radially between the jacket member and the outer core surface of the inner member with the jacket member and the inner member cooperatively applying a radial compression load to the magnet member;

the jacket member made of a carbon-carbon composite material having carbon filament and a sintered organic-free carbon matrix; and

the inner radial surface of the jacket member abutting against the outer radial surface of the magnet member to retain the magnet member in a radial position relative to the axis.

17. The turbomachine of claim 16 , wherein the inner radial surface defines an inner radius, wherein the outer radial surface defines an outer radius, and wherein the inner radius is less than the outer radius to define a radial interference fit between the jacket member and the magnet member.

18. The turbomachine of claim 16 , wherein the outer core surface includes at least one flat side.