Turbocharger with variable nozzle mechanism

Abstract

A turbocharger having a variable nozzle mechanism, which is accommodated in an accommodating chamber, is disclosed. The variable nozzle mechanism has a nozzle ring, a nozzle vane, a nozzle vane drive mechanism, and a support ring. The nozzle ring defines a gas passage through which exhaust gas is guided to a turbine wheel. The nozzle vane is supported by the nozzle ring and varies the flow area of the gas passage. The nozzle vane drive mechanism drives the nozzle vane. The support ring is connected to the nozzle ring. The nozzle vane drive mechanism is accommodated in the accommodating chamber as spaced from the nozzle ring through the support ring. The turbocharger has a drain passage that extends through a lower portion of the support ring and reaches the gas passage. The drain passage is located downward from the nozzle vane drive mechanism.

1 . A turbocharger comprising a variable nozzle mechanism accommodated in an accommodating chamber, the turbocharger having a turbine wheel rotated by receiving an exhaust gas blown from an internal combustion engine against the turbine wheel and a turbine housing accommodating the turbine wheel, wherein the variable nozzle mechanism includes:
 a nozzle ring defining a gas passage through which the exhaust gas is guided to the turbine wheel;   a nozzle vane supported by the nozzle ring to vary a flow area of the gas passage;   a nozzle vane drive mechanism that drives the nozzle vane; and   a support ring connected to the nozzle ring,   wherein the nozzle vane drive mechanism is accommodated in the accommodating chamber while being spaced from the nozzle ring by the support ring, and   wherein the turbocharger includes a drain passage extending through a lower portion of the support ring and reaching the gas passage, the drain passage being located downward from the nozzle vane drive mechanism.   
   
   
       2 . The turbocharger according to  claim 1 , wherein the drain passage extends through a lowermost portion of the support ring. 
   
   
       3 . The turbocharger according to  claim 1 , wherein the drain passage extends through the turbine housing. 
   
   
       4 . The turbocharger according to  claim 1 , wherein the support ring divides the accommodating chamber into a drive chamber and a drain chamber,
 wherein the nozzle vane drive mechanism is accommodated in the drive chamber, and   wherein the drain passage includes a drain hole formed in the support ring, the drain chamber, and another drain hole formed in the turbine housing.   
   
   
       5 . The turbocharger according to  claim 1 , wherein the support ring divides the accommodating chamber into a drive chamber and a drain chamber, wherein the nozzle vane drive mechanism is accommodated in the drive chamber, and wherein the drain passage extends through the support ring in such a manner that a lowermost portion of the drive chamber communicates with the drain chamber. 
   
   
       6 . The turbocharger according to  claim 1 , wherein the variable nozzle mechanism includes:
 a shroud connected to the nozzle ring;   the nozzle vane supported between the nozzle ring and the shroud; and   a variable transmission mechanism including a unison ring that changes the opening degree of the nozzle vane,   wherein the support ring is arranged between the unison ring and the nozzle ring, and   wherein the shroud includes a passage defining portion and a cylindrical portion, a seal ring being provided between an outer circumferential surface of the cylindrical portion and the turbine housing.