Turbocharger having variable-vane turbine nozzle including spacers that also serve as hard stops for the vanes

1. A turbocharger having a variable-nozzle turbine, comprising:

a turbine assembly comprising a turbine housing and a turbine wheel mounted in the turbine housing and connected to a rotatable shaft for rotation therewith, the turbine housing defining a chamber surrounding the turbine wheel for receiving exhaust gas and for supplying the exhaust gas to the turbine wheel, the turbine assembly defining a nozzle leading from the chamber generally radially inwardly to the turbine wheel;

a compressor assembly comprising a compressor housing and a compressor wheel mounted in the compressor housing and connected to the rotatable shaft for rotation therewith;

a center housing connected between the compressor housing and the turbine housing;

a variable-vane assembly comprising a generally annular nozzle ring and an array of vanes circumferentially spaced about the nozzle ring adjacent a first face thereof, the vanes being disposed in the nozzle such that exhaust gas flows between the vanes to the turbine wheel, each vane being rotatably mounted to the nozzle ring and connected to a rotatable actuator ring such that rotation of the actuator ring rotates the vanes for regulating exhaust gas flow to the turbine wheel;

an insert disposed in the turbine housing, the insert defining a nozzle portion axially spaced from the first face of the nozzle ring such that the vanes extend between the nozzle ring and the nozzle portion; and

a plurality of spacers connected between the nozzle portion of the insert and the nozzle ring for maintaining an axial spacing between the nozzle portion of the insert and the nozzle ring, wherein the spacers are structured and arranged to mechanically stop the vanes from rotating in one direction past a maximum-open position and to mechanically stop the vanes from rotating in an opposite direction past a minimum-open position, wherein at least one of said spacers is structured and arranged to be abutted by one of said vanes to mechanically stop the vanes from rotating in said opposite direction past said minimum-open position.

2. The turbocharger of claim 1 , wherein each vane is joined to an axle that passes through a bearing aperture in the nozzle ring, wherein an end of each axle projects out from the bearing aperture at a second face of the nozzle ring opposite from said first face and is joined to a vane arm, wherein the vane arms engage the actuator ring such that rotation of the actuator ring causes the vane arms to pivot about the axles and thereby rotate the vanes, and wherein at least one of said spacers has an extension portion that projects out from the second face of the nozzle ring and is structured and arranged to be abutted by one of said vane arms to mechanically stop the vanes from rotating in said one direction past said maximum-open position.

3. The turbocharger of claim 2 , wherein multiple ones of said spacers have extension portions that project out from the second face of the nozzle ring and are structured and arranged to be abutted respectively by multiple ones of said vane arms to mechanically stop the vanes from rotating in said one direction past said maximum-open position.

4. The turbocharger of claim 1 , wherein multiple ones of said spacers are structured and arranged to be abutted respectively by multiple ones of said vanes to mechanically stop the vanes from rotating in said opposite direction past said minimum-open position.

5. The turbocharger of claim 1 , wherein one of said spacers is structured and arranged to be abutted by another one of said vanes to mechanically stop the vanes from rotating in said one direction past said maximum-open position.

6. A turbocharger having a variable-nozzle turbine, comprising:

a turbine assembly comprising a turbine housing and a turbine wheel mounted in the turbine housing and connected to a rotatable shaft for rotation therewith, the turbine housing defining a chamber surrounding the turbine wheel for receiving exhaust gas and for supplying the exhaust gas to the turbine wheel, the turbine assembly defining a nozzle leading from the chamber generally radially inwardly to the turbine wheel;

a compressor assembly comprising a compressor housing and a compressor wheel mounted in the compressor housing and connected to the rotatable shaft for rotation therewith;

a center housing connected between the compressor housing and the turbine housing;

a variable-vane assembly comprising a generally annular nozzle ring and an array of vanes circumferentially spaced about the nozzle ring adjacent a first face thereof, the vanes being disposed in the nozzle such that exhaust gas flows between the vanes to the turbine wheel, each vane being rotatably mounted to the nozzle ring and connected to a rotatable actuator ring such that rotation of the actuator ring rotates the vanes for regulating exhaust gas flow to the turbine wheel;

an insert disposed in the turbine housing, the insert defining a nozzle portion axially spaced from the first face of the nozzle ring such that the vanes extend between the nozzle ring and the nozzle portion; and

a plurality of spacers connected between the nozzle portion of the insert and the nozzle ring for maintaining an axial spacing between the nozzle portion of the insert and the nozzle ring, wherein the spacers are structured and arranged to mechanically stop the vanes from rotating in one direction past a maximum-open position and to mechanically stop the vanes from rotating in an opposite direction past a minimum-open position, wherein at least one of said spacers is structured and arranged to be abutted by one of said vanes to mechanically stop the vanes from rotating in said one direction past said maximum-open position.