Turbocharger wheel with sound control

Abstract

A turbocharger turbine wheel includes a hub and a plurality of blades. Both the center of mass of the hub and the center of mass of the plurality of blades are on an axis of rotation. The blades are circumferentially spaced such that they are rotationally asymmetric. Each consecutive pair of blades is characterized by a spacing angle. A line that intersects with and is normal to the axis of rotation defines a plane of symmetry, and the spacing angles are symmetric across the plane of symmetry.

What is claimed is: 
     
         1 . A turbocharger wheel for use with a rotor group, comprising:
 a hub; and   a plurality of blades;   wherein the turbocharger wheel is characterized by an axis of rotation;   wherein the center of mass of the hub is on the axis of rotation;   wherein the center of mass of the plurality of blades is on the axis of rotation; and   wherein the plurality of blades is circumferentially spaced around the hub such that the plurality of blades are rotationally asymmetric around the axis of rotation.   
     
     
         2 . The turbocharger wheel of  claim 1 , wherein the wheel consists only of the hub and the plurality of blades, and wherein the hub is rotationally symmetric. 
     
     
         3 . The turbocharger wheel of  claim 1 , wherein:
 each consecutive pair of blades of the plurality of blades is characterized by a spacing angle between the consecutive pair of blades;   a plane of symmetry is defined in part by the axis of rotation, which extends along the plane of symmetry; and   the spacing angles of the plurality of blades are symmetric across the plane of symmetry.   
     
     
         4 . The turbocharger wheel of  claim 1 , wherein the wheel has a radius between 12 mm and 75 mm. 
     
     
         5 . The turbocharger wheel of  claim 4 , wherein:
 each consecutive pair of blades is characterized by a spacing angle between the consecutive pair of blades; and   each spacing angle is greater than 20.0 degrees.   
     
     
         6 . The turbocharger wheel of  claim 1 , wherein:
 each consecutive pair of blades is characterized by a spacing angle between the consecutive pair of blades; and   each spacing angle is greater than 20.0 degrees.   
     
     
         7 . A method of designing and creating turbocharger wheel tooling for creating a turbocharger wheel having n blades and an axis of rotation, comprising:
 establishing an initial spacing angle S IN  for each consecutive pair of blades;   running an iterative optimization computer program on a computer, the program being configured to solve an optimization problem using the steps of
 calculating a center of mass indicative of the center of mass of the plurality of blades with respect to the axis of rotation, 
 iteratively adjusting the spacing angles such that the distance between the calculated center of mass and the wheel axis of rotor rotation is decreased and the spacing angles vary enough to limit the acoustic energy generated at any one frequency audible to humans, and 
 continuing the iterations until the calculated center of mass is effectively on the axis of rotation and the variation of spacing angles is optimized to establish a set of final spacing angles S F  in consecutive order; and 
   once the optimization program has established a set of final spacing angles S F , forming tooling that is configured to create a void usable for creating turbocharger wheels characterized by having the set of final spacing angles S F  in consecutive order.   
     
     
         8 . The method of  claim 7 , wherein, in the step of continuing the iterations, the spacing angles are iteratively adjusted such that the variation of consecutive spacing angles is optimized. 
     
     
         9 . The method of  claim 7 , wherein:
 in the step of establishing, the initial spacing angles S IN  are selected to be symmetric across a plane of symmetry that is defined in part by the axis of rotation, which extends along the plane of symmetry; and   in the step of running an iterative optimization computer program, the iterative adjustment of the spacing angles maintains the symmetry of the spacing angles across the plane of symmetry.   
     
     
         10 . The method of  claim 9 , wherein, in the step of continuing the iterations, the spacing angles are iteratively adjusted such that the variation of consecutive spacing angles is optimized. 
     
     
         11 . The method of  claim 7 , wherein each spacing angle is constrained to be greater than a minimum spacing angle S MIN . 
     
     
         12 . The method of  claim 11 , wherein the minimum spacing angle S MIN.  is 20.0 degrees.