Patent ID: 7024855

Claim:
A turbocharger having variable turbine nozzle geometry, comprising: a turbine wheel mounted on one end of a shaft for rotation therewith about a rotation axis of the shaft; a compressor wheel mounted on an opposite end of the shaft for rotation therewith and enclosed within a compressor housing defining an air inlet and an outlet volute; a turbine housing enclosing the turbine wheel and having a volute for receiving exhaust gas from an internal combustion engine, the turbine housing defining a generally annular nozzle leading radially inward from the volute to the turbine wheel, the nozzle having an axial width defined between a first wall relatively closer to the compressor wheel and a second wall axially spaced relatively farther from the compressor wheel, the turbine housing further having a generally cylindrical inner surface spaced radially outwardly of the turbine wheel; and a piston mounted within the turbine housing concentric with the rotation axis so as to be axially slidable relative to the turbine housing for varying a size of a flow passage through the nozzle into the turbine wheel, the piston having a free end defining a free end face generally perpendicular to the rotation axis and facing toward the first wall, the piston having a generally cylindrical outer surface slidably received within the generally cylindrical inner surface of the turbine housing, the piston further comprising a radial projection at the free end, the projection extending to a larger radius than the generally cylindrical outer surface of the piston and abutting the second wall of the turbine housing when the piston is moved in a first axial direction away from the compressor wheel, thereby limiting such axial movement of the piston in said first axial direction.