Impeller with inclined and reverse inclined blades

1. A respiratory pressure therapy device for generating a supply of air at positive pressure for the amelioration or treatment of a respiratory disorder, the respiratory pressure therapy device comprising:

a device outlet configured to connect to an air circuit to deliver the supply of air to a patient via a patient interface;

a controller configured to control the respiratory pressure therapy device to provide flow rates and pressures suitable for respiratory therapy; and

a pressure generator including an impeller for a centrifugal blower, a housing for the impeller that includes an inlet and an outlet, and an electric motor configured to rotate the impeller to generate the positive pressure, wherein the impeller comprises:

a hub defining an axis of rotation for the impeller;

a plurality of inclined blades, the plurality of inclined blades extending away from the hub, each inclined blade of the plurality of inclined blades including a leading edge and a trailing edge; and

a plurality of reverse inclined blades, the plurality of reverse inclined blades extending away from the hub, each reverse inclined blade of the plurality of reversed inclined blades including a leading edge and a trailing edge,

wherein each leading edge of the plurality of inclined blades and the plurality of reverse inclined blades being the most upstream edge of the impeller in use;

wherein each trailing edge of the plurality of inclined blades and the plurality of reverse inclined blades being the most downstream edge of the impeller in use;

wherein each of the plurality of inclined blades are joined to an adjacent inclined blade at least in part by a reverse inclined blade; and

wherein at least one of the plurality of inclined blades and/or at least one of the plurality of reverse inclined blades includes serrations on a respective trailing edge.

2. The respiratory pressure therapy device of claim 1 , wherein each of the plurality of inclined blades includes serrations on a respective trailing edge.

3. The respiratory pressure therapy device of claim 1 , wherein each of the plurality of reverse inclined blades includes serrations on a respective trailing edge.

4. The respiratory pressure therapy device of claim 1 , wherein at least one of the plurality of inclined blades and/or at least one of the plurality of reverse inclined blades includes serrations on a respective leading edge.

5. The respiratory pressure therapy device of claim 4 , wherein each of the plurality of inclined blades includes serrations on a respective leading edge.

6. The respiratory pressure therapy device of claim 1 , wherein the leading edge of each inclined blade of the plurality of inclined blades is not parallel with respect to the trailing edge of each inclined blade of the plurality of inclined blades.

7. The respiratory pressure therapy device of claim 6 , wherein each of the plurality of inclined blades and each of the plurality of reverse inclined blades provide a flow path in a direction from the hub towards an outer perimeter of the impeller, wherein the flow path extends along the leading edge of each inclined blade of the plurality of inclined blades, and wherein the flow path intersects the trailing edge of each inclined blade of the plurality of inclined blades.

8. The respiratory pressure therapy device of claim 6 , further comprising an intermediate circumferential portion disposed between the hub and the trailing edges of the plurality of inclined blades and the trailing edges of the plurality of reverse inclined blades.

9. The respiratory pressure therapy device of claim 8 , wherein the intermediate circumferential portion is disposed between the leading edges of the plurality of inclined blades and the trailing edges of the plurality of inclined blades.

10. The respiratory pressure therapy device of claim 1 , wherein:

the plurality of inclined blades are inclined at a positive angle with the axis of rotation, the positive angle being neither parallel nor perpendicular;

the plurality of reverse inclined blades are inclined at a negative angle with the axis of rotation; and

the positive angle and the negative angle have the same absolute value.

11. The respiratory pressure therapy device of claim 1 , wherein a blade tip of at least one of the plurality of inclined blades and the plurality of reverse inclined blades includes serrations.

12. The respiratory pressure therapy device of claim 1 , wherein each of the plurality of inclined blades forms a substantially V-shaped cross-section with an adjacent reverse inclined blade.

13. The respiratory pressure therapy device of claim 1 , wherein the impeller further includes a sector connecting an inclined blade of the plurality of inclined blades to an adjacent reverse inclined blade of the plurality of reverse inclined blades, wherein the sector is substantially perpendicular to the axis of rotation.

14. The respiratory pressure therapy device of claim 1 , wherein the plurality of inclined blades and the plurality of reverse inclined blades define primary air passages on a first face of the impeller and secondary air passages on a second face of the impeller, and the inlet is open to and on the same side as the second face.

15. The respiratory pressure therapy device of claim 14 , wherein the impeller comprises a plurality of openings in fluid communication with the inlet, the plurality of openings being configured to allow air to flow from the second face, toward the first face and radially outward through the primary passages.

16. The respiratory pressure therapy device of claim 1 , wherein the plurality of inclined blades and the plurality of reverse inclined blades are formed without an undercut.

17. A respiratory pressure therapy device for generating a supply of air at positive pressure for the amelioration or treatment of a respiratory disorder, the respiratory pressure therapy device comprising:

a device outlet configured to connect to an air circuit to deliver the supply of air to a patient via a patient interface;

a controller configured to control the respiratory pressure therapy device to provide flow rates and pressures suitable for respiratory therapy; and

a pressure generator including an impeller for a blower, a housing for the impeller that includes an inlet and an outlet, and an electric motor configured to rotate the impeller to generate the positive pressure, wherein the impeller comprises:

a hub defining an axis of rotation for the impeller;

a plurality of inclined blades, the plurality of inclined blades extending away from the hub, each inclined blade of the plurality of inclined blades including a leading edge and a trailing edge; and

wherein each leading edge of the plurality of inclined blades being the most upstream edge of the impeller in use;

wherein each trailing edge of the plurality of inclined blades being the most downstream edge of the impeller in use;

wherein the leading edge of each inclined blade of the plurality of inclined blades is not parallel with respect to the trailing edge of each inclined blade of the plurality of inclined blades; and

wherein at least one of the plurality of inclined blades includes serrations on a respective leading edge and on a respective trailing edge.

18. The respiratory pressure therapy device of claim 17 , further comprising a plurality of reverse inclined blades, the plurality of reverse inclined blades extend away from the hub, each reverse inclined blade of the plurality of reversed inclined blades includes a leading edge and a trailing edge, wherein each leading edge of the plurality of reverse inclined blades is the most upstream edge of the impeller in use and each trailing edge is the most downstream edge of the impeller in use, wherein each of the plurality of inclined blades are joined to an adjacent inclined blade at least in part by a reverse inclined blade; and wherein at least one of the plurality of reverse inclined blades includes serrations on a respective trailing edge.

19. The respiratory pressure therapy device of claim 18 , wherein each of the plurality of inclined blades forms a substantially V-shaped cross-section with an adjacent reverse inclined blade.

20. The respiratory pressure therapy device of claim 17 , wherein each inclined blade of the plurality of inclined blades includes serrations on a respective leading edge and on a respective trailing edge.

21. The respiratory pressure therapy device of claim 17 , further comprising an intermediate circumferential portion disposed between the hub and the trailing edges of the plurality of inclined blades.

22. The respiratory pressure therapy device of claim 21 , wherein the intermediate circumferential portion is disposed between the leading edges of the plurality of inclined blades and the trailing edges of the plurality of inclined blades.

23. The respiratory pressure therapy device of claim 22 , wherein the serrations on the respective leading edge of the at least one of the plurality of inclined blades extends entirely between the intermediate circumferential portion and the hub.

24. The respiratory pressure therapy device of claim 17 , wherein the plurality of inclined blades are inclined at a positive angle with the axis of rotation, the positive angle being neither parallel nor perpendicular.

25. The respiratory pressure therapy device of claim 17 , wherein a blade tip of at least one of the plurality of inclined blades includes serrations.

26. The respiratory pressure therapy device of claim 17 , wherein each of the plurality of inclined blades at least partially forms a flow path in a direction from the hub towards an outer perimeter of the impeller, wherein the flow path extends along the leading edge of each inclined blade of the plurality of inclined blades, and wherein the flow path intersects the trailing edge of each inclined blade of the plurality of inclined blades.

27. The respiratory pressure therapy device of claim 18 , wherein the plurality of inclined blades and the plurality of reverse inclined blades are formed without an undercut.

28. The respiratory pressure therapy device of claim 1 , wherein the impeller comprises an injection moulded construction.

29. The respiratory pressure therapy device of claim 1 , wherein the impeller comprises a one-piece unitary structure.

30. The respiratory pressure therapy device of claim 17 , wherein the impeller comprises an injection moulded construction.

31. The respiratory pressure therapy device of claim 17 , wherein the impeller comprises a one-piece unitary structure.