Turbocharger comprising a variable nozzle device

Abstract

A turbocharger comprises a variable nozzle device and an exhaust housing being mechanically and/or thermally decoupled from the variable nozzle device. Additional optional advantageous features are provided, including various axial and radial clearances and various sealing elements.

1 . A turbocharger, comprising:
 a center housing;   an exhaust housing secured to the center housing;   a variable nozzle cartridge assembly positioned between the center housing and the exhaust housing, the variable nozzle cartridge assembly comprising:
 a nozzle ring; 
 an insert having an outer ring; 
 a plurality of legs configured to maintain a space between the nozzle ring and the outer ring; 
 a plurality of vanes located in the space between the nozzle ring and the outer ring; 
 a plurality of vane pins respectively secured to the vanes and rotatably received in a plurality of holes defined in the nozzle ring; 
 a plurality of vane arms located at a side of the nozzle ring opposite the vanes and secured to the vane pins; 
 a unison ring rotatably supported on the nozzle ring, the nozzle ring having a plurality of slots in which the vane arms are engaged in order to rotatably drive the vanes by a rotation of the unison ring; and 
   a plurality of rollers rotatably secured to the nozzle ring,   wherein the unison ring is rotatably supported on its inner periphery by the rollers, and   wherein the variable nozzle cartridge assembly forms a modular unit and is adapted to be assembled independent of the center housing and the exhaust housing as a separate member.   
     
     
         2 . The turbocharger according to  claim 1 , further comprising an actuating arm, an actuator rod and an actuator crank which are secured to the center housing separately from the variable nozzle cartridge assembly. 
     
     
         3 . The turbocharger according to  claim 1 , wherein the rollers comprise circumferential grooves, the unison ring being engaged with the circumferential grooves formed in the rollers. 
     
     
         4 . The turbocharger according to  claim 1 , wherein the unison ring is axially supported by the rollers. 
     
     
         5 . The turbocharger according to  claim 1 , wherein the rollers are rotatably mounted on a plurality of dowels. 
     
     
         6 . The turbocharger assembly according to  claim 5 , wherein the dowels are supported in a plurality of corresponding holes formed in the nozzle ring. 
     
     
         7 . The turbocharger according to  claim 1 , wherein the insert is formed as an integral member. 
     
     
         8 . The turbocharger according to  claim 1 , wherein the vane arms are attached to the vane pins by welding. 
     
     
         9 . The turbocharger according to  claim 1 , wherein the ring shaped insert is attachable to the center housing. 
     
     
         10 . The turbocharger according to  claim 1 , wherein a peripheral ring of the ring shaped insert is axially spaced from the exhaust housing, so that any contact between the exhaust housing and the peripheral ring is avoided. 
     
     
         11 . The turbocharger according to  claim 1 , wherein the exhaust housing is mounted directly to the center housing carrying a shaft with a turbine wheel, so that both housings define an inner space in which the variable nozzle cartridge assembly and the turbine wheel are located. 
     
     
         12 . The turbocharger according to  claim 10 , wherein the exhaust housing comprises a gas inlet portion attached to the center housing and a gas outlet portion encompassing with an axially extending clearance a gas outlet portion of the variable nozzle cartridge assembly. 
     
     
         13 . The turbocharger according to  claim 12 , wherein the gas inlet portion of the exhaust housing comprises a flange member axially abutted via a sealing element to the center housing and mounted thereto by a fastening member. 
     
     
         14 . The turbocharger according to  claim 12 , further comprising a sealing system for avoiding a gas leakage between the exhaust housing and the variable nozzle cartridge assembly. 
     
     
         15 . The turbocharger according to  claim 14 , wherein the sealing system comprises a circumferential recess formed in the gas outlet portion of the variable nozzle cartridge assembly and containing a piston ring, further comprising at least one further circumferential recess formed in the gas outlet portion of the exhaust housing and opened to the axially extending clearance between a gas inlet side of the exhaust housing and the piston ring. 
     
     
         16 . The turbocharger according to  claim 10 , wherein the nozzle ring is axially urged by the peripheral ring against an annular disc member supported on the center housing. 
     
     
         17 . The turbocharger according to  claim 12 , wherein the gas inlet portion of the exhaust housing encompasses with a further axially extending clearance the peripheral ring of the variable nozzle cartridge assembly. 
     
     
         18 . The turbocharger according to  claim 13 , wherein the peripheral ring is abutted against the sealing element via which the flange member of the exhaust housing is secured on the center housing.