Rotary machine including a machine rotor with a composite impeller portion and a metal shaft portion

1. A rotary machine, comprising:

a machine stator; and

a machine rotor rotatable relative to the machine stator and comprising a metal shaft portion, a composite impeller, and at least one first metal ring portion securing the composite impeller to the metal shaft portion, the at least one first metal ring portion comprising a first interface with the composite impeller and a second interface with the metal shaft portion,

wherein the composite impeller comprises a composite impeller portion and a metal attachment portion for engaging the metal shaft portion;

wherein the metal attachment portion comprises a hub portion and a radially extending portion extending radially outwardly from the hub portion, and

wherein at least a part of the radially extending portion is positioned between a part of the first metal ring portion and an outer surface of the composite impeller portion.

2. The rotary machine of claim 1 , wherein a force exerted by the at least one first metal ring portion against the composite impeller is configured to prevent movement between the composite impeller and the metal shaft portion.

3. The rotary machine of claim 2 , wherein a force exerted by the at least one first metal ring portion against the metal shaft portion is configured to prevent movement between the at least one first metal ring portion and the metal shaft portion.

4. The rotary machine of claim 3 , wherein the at least one first metal ring portion is disposed on a first side of the composite impeller, and a second metal ring portion is disposed on a second side of the composite impeller, the second metal ring portion further securing the composite impeller to the metal shaft portion, the second metal ring portion comprising a first interface with the composite impeller and a second interface with the metal shaft portion.

5. The rotary machine of claim 4 , wherein the first interface of the at least one first metal ring portion defines a tubular shape, and the second interface of the at least one first metal ring portion defines a tubular shape.

6. The rotary machine of claim 2 , wherein the at least one first metal ring portion is disposed on a first side of the composite impeller, and a second metal ring portion is disposed on a second side of the composite impeller, the second metal ring portion further securing the composite impeller to the metal shaft portion, the second metal ring portion comprising a first interface with the composite impeller and a second interface with the metal shaft portion.

7. The rotary machine of claim 2 , wherein the composite impeller comprises an attachment portion for engaging the metal shaft portion.

8. The rotary machine of claim 2 , wherein the first interface of the at least one first metal ring portion defines a tubular shape, and the second interface of the at least one first metal ring portion defines a tubular shape.

9. The rotary machine of claim 1 , wherein a force exerted by the at least one first metal ring portion against the metal shaft portion is configured to prevent movement between the at least one first metal ring portion and the metal shaft portion.

10. The rotary machine of claim 1 , wherein the at least one first metal ring portion is disposed on a first side of the composite impeller, and a second metal ring portion is disposed on a second side of the composite impeller, the second metal ring portion further securing the composite impeller to the metal shaft portion, the second metal ring portion comprising a first interface with the composite impeller and a second interface with the metal shaft portion.

11. The rotary machine of claim 1 , wherein the first interface defines a tubular shape, and the second interface defines a tubular shape.

12. A machine rotor, comprising:

a metal shaft;

a composite impeller comprising a composite impeller portion and an attachment portion comprising a metal portion, the composite impeller being disposed on the metal shaft; and

a metal ring shrink fit to the attachment portion and the metal shaft to secure the composite impeller to the metal shaft,

wherein the attachment portion comprises a hub portion and a radially extending portion extending radially outwardly from the hub portion, and wherein at least a part of the radially extending portion is positioned between a part of the metal ring and an outer surface of the composite impeller portion.

13. A method of securing a composite impeller to a metal shaft of a machine rotor, the method comprising:

positioning the composite impeller onto the metal shaft;

heating at least one first metal ring;

positioning the at least one first metal ring onto the metal shaft; and

allowing the at least one first metal ring to cool and shrink into engagement with the composite impeller and the metal shaft to secure the composite impeller to the metal shaft,

wherein the composite impeller comprises a composite impeller portion and a metal attachment portion for engaging the metal shaft;

wherein the metal attachment portion comprises a hub portion and a radially extending portion extending radially outwardly from the hub portion, and wherein at least a part of the radially extending portion is positioned between a part of the at least one first metal ring and an outer surface of the composite impeller portion.