Turbo Wheel And Shaft Assembly

Abstract

A turbine wheel and shaft assembly is provided for a turbocharger including a turbine wheel including a body portion supporting a plurality of blades on a first axial face thereof. A hub extends from a body portion on a second axial face. A shaft is welded to the hub at a weld location spaced from the second axial face. The weld location is spaced axially from the second axial face by a distance sufficient to provide a significant reduction in the residual stresses in the welded parts. This design is intended to mitigate turbine wheel imbalance problems.

What is claimed is: 
     
         1 . A turbine wheel and shaft assembly for a turbocharger, comprising:
 a turbine wheel including a body portion supporting a plurality of blades on a first axial face thereof and a hub extending from said body portion on a second axial face, said hub having a diameter;   a shaft welded to said hub at a weld location spaced from said second axial face, wherein said weld location is spaced axially from said second axial face of said body portion by a distance that is at least 50 percent of said diameter.   
     
     
         2 . The turbine wheel and shaft assembly according to  claim 1 , wherein said shaft includes a cylindrical body and a radially extending flange portion at an end thereof that is welded to said hub of said turbine wheel. 
     
     
         3 . The turbine wheel and shaft assembly according to  claim 1 , wherein said shaft is hollow. 
     
     
         4 . The turbine wheel and shaft assembly according to  claim 1 , wherein said hub includes a hollow portion therein. 
     
     
         5 . A turbocharger, comprising:
 a housing including an inlet for receiving an engine exhaust gas flow, a turbine chamber and an outlet for exhaust gas discharge;   a turbine wheel and shaft assembly disposed in said turbine chamber and including a turbine wheel having a body portion supporting a plurality of blades on a first axial face thereof and a hub extending from said body portion on a second axial face opposite the first axial face, said hub having a diameter, and a shaft having a first end welded to said hub at a weld location spaced from said second axial face, wherein said weld location is spaced axially from said second axial face of said body portion by a distance that is at least 50 percent of said diameter.   
     
     
         6 . The turbocharger according to  claim 5 , wherein said shaft includes a cylindrical body and a radially extending flange portion at the first end thereof that is welded to said hub of said turbine wheel. 
     
     
         7 . The turbocharger according to  claim 5 , wherein said shaft is hollow. 
     
     
         8 . The turbo charger according to  claim 5 , wherein said hub includes a hollow portion therein. 
     
     
         9 . The turbo charger according to  claim 5 , further comprising a compressor wheel attached to a second end of said shaft and disposed in a compressor chamber. 
     
     
         10 . The turbo charger according to  claim 5 , further comprising a seal disposed between said second axial face of said turbine wheel and said weld location. 
     
     
         11 . An engine, comprising:
 an engine structure defining a plurality of cylinders receiving a respective piston therein and having inlet and exhaust passages in communication with each of the cylinders;   a turbocharger comprising:
 a housing including an inlet for receiving an engine exhaust gas flow from said exhaust passages, a turbine chamber and an outlet for exhaust gas discharge; 
 a turbine wheel and shaft assembly disposed in said turbine chamber and including a turbine wheel having a body portion supporting a plurality of blades on a first axial face thereof and a hub extending from said body portion on a second axial face opposite the first axial face, said hub having a diameter, and a shaft welded to said hub at a weld location spaced from said second axial face, wherein said weld location is spaced axially from said second axial face of said body portion by a distance that is at least 50 percent of said diameter. 
   
     
     
         12 . The engine according to  claim 11 , wherein said shaft includes a cylindrical body and a radially extending flange portion at an end thereof that is welded to said hub of said turbine wheel. 
     
     
         13 . The engine according to  claim 11 , wherein said shaft is hollow. 
     
     
         14 . The engine according to  claim 11 , wherein said hub includes a hollow portion therein. 
     
     
         15 . The engine according to  claim 11 , further comprising a compressor wheel attached to a second end of said shaft and disposed in a compressor chamber. 
     
     
         16 . The engine according to  claim 15 , wherein said compressor chamber is in communication with an air inlet and a compressed air outlet that is in communication with said inlet passages of said cylinders. 
     
     
         17 . The engine according to  claim 11 , further comprising a seal disposed between said second axial face of said turbine wheel and said weld location.