Variable-nozzle turbine with means for radial locating of variable-nozzle cartridge
A turbocharger having a variable-nozzle turbine formed by pivotable vanes supported by a nozzle ring includes a locator that is radially elastically deformable and is disposed between a radially outwardly facing surface of the center housing and an opposing surface of the nozzle ring for radially locating the nozzle ring relative to the center housing. At least one vent is defined in either a radially outermost surface of the locator or the surface of the nozzle ring to allow pressure communication between spaces on axially opposite sides of the locator.
1. A turbocharger having a variable-nozzle turbine, comprising:
a turbine 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 flow, and an axially extending bore through which exhaust gas is discharged after passing through the turbine wheel;
a nozzle leading from the chamber generally radially inward to the turbine wheel;
a compressor 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 and having a nose portion adjacent the turbine wheel defining a generally radially outward facing first surface and a second surface that faces generally axially toward the turbine wheel;
a generally annular nozzle ring having a first face comprising one wall of the nozzle and axially spaced from an opposite wall of the nozzle and having an opposite second face, and an array of vanes circumferentially spaced about the generally annular nozzle ring and disposed in the nozzle, the array of vanes being rotatably mounted to the generally annular nozzle ring such that the array of vanes are variable in setting angle for regulating the exhaust gas flow to the turbine wheel, the generally annular nozzle ring adjacent an inner diameter thereof defining a generally radially inward facing third surface spaced apart from and opposing the first surface of the nose portion of the center housing;
a spring heat shroud that is resiliently axially compressible, the spring heat shroud having a radially outer peripheral portion in contact with a portion of the second face of the generally annular nozzle ring, and having a radially inner peripheral portion in contact with the second surface of the nose portion of the center housing that faces toward the turbine wheel, the spring heat shroud being axially compressed between the generally annular nozzle ring and the nose portion of the center housing; and
a locator defined by a metallic ring disposed between the first surface of the nose portion of the center housing and the opposing third surface of the generally annular nozzle ring and serving to radially locate the nozzle ring relative to the center housing, the locator being radially compressible in an elastically deformable manner, the locator having a radially outermost surface and a radially innermost surface, the radially innermost surface of the locator contacting the first surface of the nose portion of the center housing, the radially outermost surface of the locator contacting the third surface of the generally annular nozzle ring;
wherein at least one of the radially outermost surface of the locator and the third surface of the generally annular nozzle ring defines at least one vent comprising a radially extending recess in said at least one surface, the at least one vent providing fluid pressure communication between spaces (P 1 ,P 2 ) on axially opposite sides of the locator.
2. The turbocharger of claim 1 , wherein the at least one vent is a plurality of said vents which are circumferentially spaced apart about a circumference of the locator.
3. The turbocharger of claim 2 , wherein the plurality of said vents are defined in the third surface of the generally annular nozzle ring.
4. The turbocharger of claim 2 , wherein the plurality of said vents are defined in the radially outermost surface of the locator.