Charging device

1. A charging device comprising:

a variable turbine geometry located between a bearing housing and a turbine housing, wherein said variable turbine geometry includes at least one guide blade rotatably mounted in a blade bearing ring, wherein at least one side of the blade bearing ring is directly exposed to a hot gas flow, while an opposing side of the blade bearing ring faces away from said hot gas flow and is indirectly exposed to the hot gas flow such that the blade bearing ring side directly exposed to the hot gas flow is produced of a first material and the opposing side that is indirectly exposed to the hot gas flow is produced of a second material, wherein the two materials having heat expansion coefficients are selected such that the blade bearing ring such that the blade bearing at operating temperatures expands evenly without warping; and wherein the blade bearing ring is configured from at least two discs with different materials, wherein the materials used have different heat expansion coefficients.

2. A charging device comprising:

a variable turbine geometry located between a bearing housing and a turbine housing, wherein said variable turbine geometry includes at least one guide blade rotatably mounted in a blade bearing ring, wherein at least one side of the blade bearing ring is directly exposed to a hot gas flow, while an opposing side of the blade bearing ring faces away from said hot gas flow and is indirectly exposed to the hot gas flow-such that the blade bearing ring side directly exposed to the hot gas flow is produced of a first material and the opposing side that is indirectly exposed to the hot gas flow is produced of a second material, wherein the two materials having heat expansion coefficients are selected such that the blade bearing ring-operating temperatures expands evenly without warping; and wherein the material of the blade bearing ring directly exposed to the hot gas flow has a lower heat expansion coefficient than the material exposed only indirectly to the hot gas flow.

3. The charging device according to claim 1 , wherein the at least two discs of the blade bearing ring are cast together in a fixed manner.

4. The charging device according to claim 1 , wherein the at least two discs of the blade bearing ring are connected with each other by a metal injection moulding method (MIM).

5. The charging device according to claim 1 , wherein the at least two discs of the blade bearing ring are connected with each other by a sintering method.

6. A charging device comprising:

a variable turbine geometry located between a bearing housing and a turbine housing, wherein said variable turbine geometry includes at least one guide blade rotatably mounted in a blade bearing ring, wherein at least one side of the blade bearing ring is directly exposed to a hot gas flow, while an opposing side of the blade bearing ring faces away from said hot gas flow and is indirectly exposed to the hot gas flow-such that the blade bearing ring side directly exposed to the hot gas flow is produced of a first material and the opposing side that is indirectly exposed to the hot gas flow is produced of a second material, wherein the two materials having heat expansion coefficients are selected such that the blade bearing ring-operating temperatures expands evenly without warping; and wherein at least one of the side of the blade bearing ring directly exposed to the hot gas flow and at least one disc has a temperature protection coating.

7. The charging device according to claim 6 , wherein the temperature protection coating comprises at least austenite.

8. The charging device according to claim 6 , wherein the disc and the temperature protection coating are materially connected with each other.

9. The charging device according to claim 1 , wherein the blade bearing ring is produced of at least three discs with different materials, wherein the materials used have different heat expansion coefficients.

10. The charging device according to claim 1 , wherein the material of the blade bearing ring directly exposed to the hot gas flow has a lower heat expansion coefficient than the material exposed only indirectly to the hot gas flow.

11. The charging device according to claim 2 , wherein the at least two discs of the blade bearing ring are cast together in a fixed manner.

12. The charging device according to claim 2 , wherein the at least two discs of the blade bearing ring are connected with each other by a metal injection moulding method (MIM).

13. The charging device according to claim 2 , wherein the at least two discs of the blade bearing ring are connected with each other by a sintering method.

14. The charging device according to claim 1 , wherein at least one of the side of the blade bearing ring directly exposed to the hot gas flow and at least one disc has a temperature protection coating.

15. The charging device according to claim 2 , wherein at least one of the side of the blade bearing ring directly exposed to the hot gas flow and at least one disc has a temperature protection coating.

16. The charging device according to claim 7 wherein the disc and the temperature protection coating are materially connected with each other.

17. The charging device according to claim 1 , wherein the blade bearing ring is produced of at least three discs with different materials, wherein the materials used have different heat expansion coefficients.

18. The charging device according to claim 2 , wherein the blade bearing ring is produced of at least three discs with different materials, wherein the materials used have different heat expansion coefficients.

19. The charging device according to claim 3 , wherein the blade bearing ring is produced of at least three discs with different materials, wherein the materials used have different heat expansion coefficients.