Variable nozzle unit and variable geometry turbocharger
In a variable nozzle unit, at a position located away from and opposed to a first nozzle ring in a right-left direction, a second nozzle ring is provided integrally with the first nozzle ring through multiple connecting pins arranged in a circumferential direction. An inner edge portion of a support ring is connected to the first nozzle ring by riveting of one end portions of the multiple connecting pins. Each pin hole in the support ring is formed into such a shape extending in a radial direction of the support ring. A washer is provided between a rim of each pin hole in the support ring and a rivet head brought about by joining of the end portion of the corresponding connecting pin.
1. A variable nozzle unit configured to adjust a passage area for an exhaust gas to be supplied to a turbine wheel side of a variable geometry turbocharger, comprising:
an annular first wall member disposed inside a turbine housing of the variable geometry turbocharger and concentrically with the turbine wheel;
an annular second wall member provided integrally with the first wall member at a position located away from and opposed to the first wall member in an axial direction, by using a plurality of connecting pins arranged at intervals in a circumferential direction;
a plurality of variable nozzles disposed between an opposed surface of the first wall member and an opposed surface of the second wall member at intervals in the circumferential direction, each variable nozzle being turnable in forward and reverse directions around a shaft center parallel to a shaft center of the turbine wheel;
a link mechanism that is movable in engagement with the annular first wall member or the annular second wall member and configured to synchronously turn the plurality of variable nozzles; and
a support ring being connected to the first wall member by joining of one end portions of the plurality of connecting pins, the support ring including a plurality of pin holes to allow insertion of the one end portions of the plurality of connecting pins, respectively, the pin holes being penetratingly formed in at intervals in the circumferential direction, wherein
each pin hole in the support ring is formed into an elongated shape extending from an inner edge portion side toward an outer edge portion side of the support ring, and
the support ring relatively moves the plurality of connecting pins along the elongated shape of each pin hole and absorbs a difference in thermal expansion in a radial direction between the first wall member and the support ring when the variable geometry turbocharger is in operation.
2. The variable nozzle unit according to claim 1 , wherein a washer is provided between a rim of each pin hole in the support ring and a joining portion brought about by joining of the one end portion of the corresponding connecting pin.
3. The variable nozzle unit according to claim 1 , wherein each pin hole is a slit.
4. The variable nozzle unit according to claim 1 , wherein
a plurality of support holes are penetratingly formed in the first wall member at intervals in the circumferential direction,
a nozzle shaft of each variable nozzle is turnably supported by a corresponding one of the support holes in the first wall member, and
an opposite surface side from the opposed surface of the first wall member communicates with a turbine scroll passage of the turbine housing.
5. A variable geometry turbocharger configured to supercharge air to be supplied to an engine side by using energy of an exhaust gas from the engine, comprising:
the variable nozzle unit according to claim 1 .
6. The variable nozzle unit according to claim 1 , wherein a shape of each pin hole in an oval shape.
7. The variable nozzle unit according to claim 1 , wherein a shape of each pin hole is an elongated hole shape with two parallel long sides.