Mounting structure for variable nozzle mechanism in variable-throat exhaust turbocharger

Abstract

Provided is a variable-throat exhaust turbocharger in which a nozzle assembly including a nozzle mount and nozzle vanes has a firm support structure without affection by a thermal deformation of a turbine casing and an external force exerted to the turbine casing, and a scroll portion is formed in a substantially opened configuration so that the nozzle assembly can be simply formed in order to reduce the number of mold cores for a scroll during casting of the turbine casing, thereby it is possible to enhance the productivity of the turbine casing.

1 . A mounting structure for a variable nozzle mechanism which is incorporated in a variable-throat exhaust turbocharger, and in which exhaust gas from an engine is led through a scroll formed in a turbine casing, and a plurality of nozzle vanes arranged on the inner peripheral side of the scroll, and is then applied to a turbine rotor provided in the inner peripheral side of the nozzle vanes, and the plurality of nozzle vanes are rotatably supported on an annular nozzle mount so as to change the blade angle of the nozzle vanes in order to regulate the flow rate of the exhaust gas applied onto the turbine rotor, characterized in that an annularly formed insert member is removable attached to the outer periphery of the nozzle mount, and the insert member is fitted at its outer periphery in an attaching bore which is formed in the turbine casing and which is opened from the scroll toward a bearing housing, and the insert member is attached to the bearing housing. 
   
   
       2 . A mounting structure for a variable nozzle mechanism which is incorporated in a variable-throat exhaust turbocharger, and in which exhaust gas from an engine is led through a scroll formed in a turbine casing, and a plurality of nozzle vanes arranged on the inner peripheral side of the scroll, and is then applied to a turbine rotor provided in the inner peripheral side of the nozzle vanes, and the plurality of nozzle vanes are rotatably supported on an annular nozzle mount so as to change the blade angle of the nozzle vanes in order to regulate the flow rate of the exhaust gas applied onto the turbine rotor, characterized in that the nozzle mount and an insert member are integrally incorporated with each other so as to form an integrated nozzle mount type insert member, the integrated nozzle mount type insert member is fitted at its outer periphery in an attaching bore which is formed in the turbine casing and which is opened from the scroll toward a bearing housing, and the integrated nozzle mount type insert member is attached to the bearing housing. 
   
   
       3 . A mounting structure for a variable nozzle mechanism in a variable-throat exhaust turbocharger according to  claim 2 , characterized in that the insert member is attached thereto with the nozzle mount and a variable nozzle mechanism member including the nozzle vanes attached to the nozzle mount so as to form an integrated nozzle mount and insert member assembly structure, and the nozzle mount and insert member assembly structure is fixed to the bearing housing by fastening members including bolts and attaching screws. 
   
   
       4 . A mounting structure for a variable nozzle mechanism in a variable-throat exhaust turbocharger according to  claim 1 , characterized in that the inset member is formed in its outer peripheral part with a flange part, the flange part is clamped between flange parts formed in the turbine casing and the bearing housing, and the thus formed clamped parts are joined at their outer peripheries by a coupling in a fluid tight manner. 
   
   
       5 . A mounting structure for a variable nozzle mechanism in a variable-throat exhaust turbocharger according to  claim 1 , characterized in that a snap ring is fitted in a ring groove formed in a side end part of the bearing housing in the turbine casing, and the outer peripheral parts of the bearing housing and the insert member are clamped between the snap ring and the turbine casing, and the bearing housing and the insert member are fixed to the turbine casing by a side surface of the snap ring. 
   
   
       6 . A mounting structure for a variable nozzle mechanism in a variable-throat exhaust turbocharger according to  claim 1 , characterized in that a female thread is formed in the attaching bore in the turbine casing while a male thread is formed at the outer periphery of the insert member, and the outer peripheral part of the insert member is fixed between the turbine casing and the bearing housing by meshing the female thread with the male thread. 
   
   
       7 . A mounting structure for a variable nozzle mechanism in a variable-throat exhaust turbocharger according to  claim 1 , characterized in that the outer peripheral part of the insert member is fixed to the bearing housing and the turbine casing by welding. 
   
   
       8 . A mounting structure for a variable nozzle mechanism in a variable-throat exhaust turbocharger according to  claim 1 , characterized in that a piston ring for fluid tight sealing is fitted between the outer periphery of the insert member and the inner periphery of the attaching bore in the turbine casing, and the outer peripheral surface of the piston ring is made into slidable contact with the inner peripheral surface of the attaching bore in the turbine casing. 
   
   
       9 . A mounting structure for a variable nozzle mechanism in a variable-throat exhaust turbocharger according to  claim 1 , characterized in that a piston ring for fluid tight sealing is fitted between the inner peripheral surface of the insert member and the outer peripheral surface of the nozzle mount which is faced to the inner peripheral surface. 
   
   
       10 . A mounting structure for a variable nozzle mechanism which is incorporated in a variable-throat exhaust turbocharger, and in which exhaust gas from an engine is led through a scroll formed in a turbine casing, and a plurality of nozzle vanes arranged on the inner peripheral side of the scroll, and is then applied to a turbine rotor provided in the inner peripheral side of the nozzle vanes, and the plurality of nozzle vanes are rotatably supported on an annular nozzle mount so as to change the blade angle of the nozzle vanes in order to regulate the flow rate of the exhaust gas applied onto the turbine rotor, characterized in that the turbine casing is formed therein with an opening which has no protrusion projected from the inner peripheral surface toward the outer periphery surface of the scroll, and which is axially linear, an insert shroud having a protrusion which is projected toward the outer periphery of the scroll and which serves as a part of the inner surface of the scroll is attached to the opening, and a support part of an annular nozzle plate which is coupled to the nozzle mount through the intermediary of a nozzle support is formed in the insert shroud. 
   
   
       11 . A mounting structure for a variable nozzle mechanism which is incorporated in a variable-throat exhaust turbocharger, and in which exhaust gas from an engine is led through a scroll formed in a turbine casing, and a plurality of nozzle vanes arranged on the inner peripheral side of the scroll, and is then applied to a turbine rotor provided in the inner peripheral side of the nozzle vanes, and the plurality of nozzle vanes are rotatably supported on an annular nozzle mount so as to change the blade angle of the nozzle vanes in order to regulate the flow rate of the exhaust gas applied onto the turbine rotor, characterized in that an annularly formed insert member is removable attached to the outer periphery of the nozzle mount, and the insert member is fitted at its outer periphery in an attaching bore which is formed in the turbine casing and which is opened from the scroll toward the bearing housing, the insert member is attached to the bearing housing, further, the turbine casing is formed therein with an opening which has no protrusion projected from the inner peripheral surface toward the outer peripheral surface of the scroll and which is axially linear, an insert shroud having a protrusion which is projected toward the outer periphery of the scroll and which serves as a part of the inner surface of the scroll is attached to the opening, and a support part of an annular nozzle plate coupled to the nozzle mount through the intermediary of a nozzle support is formed in the insert shroud. 
   
   
       12 . A mounting structure for a variable nozzle mechanism in a variable-throat exhaust turbocharger according to  claim 2 , characterized in that the inset member is formed in its outer peripheral part with a flange part, the flange part is clamped between flange parts formed in the turbine casing and the bearing housing, and the thus formed clamped parts are joined at their outer peripheries by a coupling in a fluid tight manner. 
   
   
       13 . A mounting structure for a variable nozzle mechanism in a variable-throat exhaust turbocharger according to  claim 2 , characterized in that a snap ring is fitted in a ring groove formed in a side end part of the bearing housing in the turbine casing, and the outer peripheral parts of the bearing housing and the insert member are clamped between the snap ring and the turbine casing, and the bearing housing and the insert member are fixed to the turbine casing by a side surface of the snap ring. 
   
   
       14 . A mounting structure for a variable nozzle mechanism in a variable-throat exhaust turbocharger according to  claim 2 , characterized in that a female thread is formed in the attaching bore in the turbine casing while a male thread is formed at the outer periphery of the insert member, and the outer peripheral part of the insert member is fixed between the turbine casing and the bearing housing by meshing the female thread with the male thread. 
   
   
       15 . A mounting structure for a variable nozzle mechanism in a variable-throat exhaust turbocharger according to  claim 2 , characterized in that the outer peripheral part of the insert member is fixed to the bearing housing and the turbine casing by welding. 
   
   
       16 . A mounting structure for a variable nozzle mechanism in a variable-throat exhaust turbocharger according to  claim 2 , characterized in that a piston ring for fluid tight sealing is fitted between the outer periphery of the insert member and the inner periphery of the attaching bore in the turbine casing, and the outer peripheral surface of the piston ring is made into slidable contact with the inner peripheral surface of the attaching bore in the turbine casing.