Turbocharger turbine wheel

1. An exhaust turbocharger turbine wheel comprising:

a hub that comprises a nose, a backdisk with a shaft joint portion, and a rotational axis;

a number of blades that extend from the hub to define exhaust flow channels wherein each of the blades comprises a leading edge, a trailing edge, a hub profile, a shroud profile, a pressure side, and a suction side, wherein the leading edge meets the backdisk and the trailing edge meets the hub;

wherein the backdisk comprises an outer perimeter radius measured from the rotational axis of the hub, an intermediate radius at an outer perimeter of the shaft joint portion measured from the rotational axis of the hub, and an annular recess disposed between the intermediate radius and the outer perimeter radius and defined in part by a number of discrete three-dimensional bolster regions, wherein each of the discrete three-dimensional bolster regions comprises a material volume defined in part by a footprint and a height at least in part in a direction of the rotational axis of the hub, wherein the number of discrete three-dimensional bolster regions is at least five and equal to the number of blades, wherein each of the discrete three-dimensional bolster regions is offset to the suction side of a respective one of the blades, wherein the annular recess comprises a surface that is disposed between the intermediate radius and the outer perimeter radius and that is defined in part by the discrete three-dimensional bolster regions, and wherein each of the discrete three-dimensional bolster regions is a surface bulge of the surface and within the annular recess.

2. The exhaust turbocharger turbine wheel of claim 1 wherein the shaft joint portion comprises a shaft joint surface that comprises a shaft joint radius, wherein the backdisk comprises a relative radius that is less than 0.5 and greater than 0.2 wherein the relative radius is defined as a difference between the intermediate radius at the outer perimeter of the shaft joint portion and the shaft joint radius divided by a difference between the outer perimeter radius and the shaft joint radius.

3. The exhaust turbocharger turbine wheel of claim 1 wherein the exhaust turbocharger turbine wheel is a radial inflow exhaust turbocharger turbine wheel.

4. The exhaust turbocharger turbine wheel of claim 1 wherein the exhaust turbocharger turbine wheel is a mixed-flow inflow exhaust turbocharger turbine wheel.

5. The exhaust turbocharger turbine wheel of claim 1 wherein the backdisk comprises scalloped regions to define a scalloped perimeter.

6. The exhaust turbocharger turbine wheel of claim 5 wherein the backdisk comprises blade joining regions and wherein each of the scalloped regions is disposed between two of the blade joining regions.

7. The exhaust turbocharger turbine wheel of claim 1 wherein the footprint comprises a closed curve perimeter.

8. The exhaust turbocharger turbine wheel of claim 1 wherein each of the discrete three-dimensional bolster regions comprises a corresponding fillet region.

9. The exhaust turbocharger turbine wheel of claim 1 wherein each of the discrete three-dimensional bolster regions comprises a geometric centroid.

10. The exhaust turbocharger turbine wheel of claim 9 wherein each of the geometric centroids is offset from a corresponding blade joining region of the backdisk toward the suction side of a corresponding one of the blades.

11. The exhaust turbocharger turbine wheel of claim 1 comprising less than thirty-one of the discrete three-dimensional bolster regions.

12. The exhaust turbocharger turbine wheel of claim 1 , wherein the material volumes of the number of discrete three-dimension bolster regions comprise balancing stock for cutting away during a balancing process of the exhaust turbocharger turbine wheel.

13. The exhaust turbocharger turbine wheel of claim 1 , wherein at least one of the discrete three-dimension bolster regions comprises a balancing cut that diminishes its material volume.

14. The exhaust turbocharger turbine wheel of claim 1 , wherein the material volumes of the number of discrete three-dimensional bolster regions define at least a portion of a balancing capacity of the exhaust turbocharger turbine wheel.

15. The exhaust turbocharger turbine wheel of claim 1 , wherein each of the discrete three-dimensional bolster regions is positioned at a stress spot that reinforces the backdisk.

16. The exhaust turbocharger turbine wheel of claim 1 , wherein each of the discrete three-dimensional bolster regions is disposed azimuthally between the suction side of a first one of a pair of the blades and the pressure side of a second one of the pair of the blades and disposed closer to the suction side of the first one of the pair of the blades.

17. A method comprising:

for an exhaust turbocharger turbine wheel comprising: a hub that comprises a nose, a backdisk with a shaft joint portion, and a rotational axis; a number of blades that extend from the hub to define exhaust flow channels wherein each of the blades comprises a leading edge, a trailing edge, a hub profile, a shroud profile, a pressure side, and a suction side, wherein the leading edge meets the backdisk and the trailing edge meets the hub; wherein the backdisk comprises an outer perimeter radius measured from the rotational axis of the hub, an intermediate radius at an outer perimeter of the shaft joint portion measured from the rotational axis of the hub, and an annular recess disposed between the intermediate radius and the outer perimeter radius and defined in part by a number of discrete three-dimensional bolster regions, wherein each of the discrete three-dimensional bolster regions comprises a material volume defined in part by a footprint and a height measured at least in part in a direction of the rotational axis of the hub, wherein the number of discrete three-dimensional bolster regions is at least five and equal to the number of blades, wherein each of the discrete three-dimensional bolster regions is offset to the suction side of a respective one of the blades, wherein the annular recess comprises a surface that is disposed between the intermediate radius and the outer perimeter radius and that is defined in part by the discrete three-dimensional bolster regions, and wherein each of the discrete three-dimensional bolster regions is a surface bulge of the surface and within the annular recess, removing material from the shaft joint portion to form a balanced exhaust turbocharger turbine wheel; and

installing the balanced exhaust turbocharger turbine wheel in a turbocharger.

18. The method of claim 17 further comprising operating the turbocharger by flowing exhaust from an internal combustion engine to the turbocharger to rotate the balanced exhaust turbocharger turbine wheel.

19. An exhaust turbocharger turbine wheel comprising:

a hub that comprises a nose, a backdisk with a shaft joint portion, and a rotational axis;

a number of blades that extend from the hub to define exhaust flow channels wherein each of the blades comprises a leading edge, a trailing edge, a hub profile, a shroud profile, a pressure side, and a suction side, wherein the leading edge meets the backdisk and the trailing edge meets the hub;

wherein the backdisk comprises an outer perimeter radius measured from the rotational axis of the hub, an intermediate radius at an outer perimeter of the shaft joint portion measured from the rotational axis of the hub, and an annular recess disposed between the intermediate radius and the outer perimeter radius and defined in part by a number of discrete three-dimensional bolster regions, wherein each of the discrete three-dimensional bolster regions comprises a material volume defined in part by a footprint and a height at least in part in a direction of the rotational axis of the hub, wherein the number of discrete three-dimensional bolster regions is at least five and equal to the number of blades, wherein each of the discrete three-dimensional bolster regions is disposed azimuthally between the suction side of a first one of a pair of the blades and the pressure side of a second one of the pair of the blades and disposed closer to the suction side of the first one of the pair of the blades, wherein the annular recess comprises a surface that is disposed between the intermediate radius and the outer perimeter radius and that is defined in part by the discrete three-dimensional bolster regions, and wherein each of the discrete three-dimensional bolster regions is a surface bulge of the surface and within the annular recess.