Variable nozzle unit and variable geometry turbocharger

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 being disposed inside a turbine housing of the variable geometry turbocharger and concentrically with the turbine wheel, and including a plurality of attachment holes penetratingly formed in the annular first wall member at intervals in a circumferential direction;

an annular second wall member provided at a position located away from and opposed to the annular first wall member in an axial direction;

a plurality of connecting pins provided in an integrally connected manner between the annular first wall member and the annular second wall member and arranged at intervals in the circumferential direction, in which one end portion of each connecting pin of the plurality of connecting pins is joined in a state of being inserted into the corresponding attachment hole in the annular first wall member;

a plurality of variable nozzles disposed between an opposed surface of the annular first wall member and an opposed surface of the annular second wall member at intervals in the circumferential direction, each variable nozzle of the plurality of variable nozzles 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 provided on an opposite surface from the opposed surface of the annular first wall member, and integrally connected to the annular first wall member by joining of the 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 connecting pins, the pin holes being penetratingly formed so as to be aligned with the plurality of attachment holes in the annular first wall member, wherein a cutout is formed at a region on an outer side in a radial direction and a region on an inner side in the radial direction at a rim on an axially one side of each attachment hole of the plurality of attachment holes in the annular first wall member, and at the region on an outer side in the radial direction and a region on an inner side in the radial direction at a rim on an axially other side of each pin hole of the plurality of pin holes in the support ring, respectively.

2. 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 .

3. 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 being disposed inside a turbine housing of the variable geometry turbocharger and concentrically with the turbine wheel, and including a plurality of attachment holes penetratingly formed in the annular first wall member at intervals in a circumferential direction;

an annular second wall member provided at a position located away from and opposed to the annular first wall member in an axial direction;

a plurality of connecting pins provided in an integrally connected manner between the annular first wall member and the annular second wall member and arranged at intervals in the circumferential direction, in which one end portion of each connecting pin of the plurality of connecting pins is joined in a state of being inserted into the corresponding attachment hole in the annular first wall member;

a plurality of variable nozzles disposed between an opposed surface of the annular first wall member and an opposed surface of the annular second wall member at intervals in the circumferential direction, each variable nozzle of the plurality of variable nozzles 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 provided on an opposite surface from the opposed surface of the annular first wall member, and integrally connected to the annular first wall member by joining of the 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 connecting pins, the pin holes being penetratingly formed so as to be aligned with the plurality of attachment holes in the annular first wall member,

wherein a chamfer is formed at a rim on an axially one side of each attachment hole of the plurality of attachment holes in the annular first wall member and at a rim on an axially other side of each pin hole of the plurality of pin holes in the support ring, respectively.

4. 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 3 .

5. 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 being disposed inside a turbine housing of the variable geometry turbocharger and concentrically with the turbine wheel, and including a plurality of first attachment holes penetratingly formed in the annular first wall member at intervals in a circumferential direction;

an annular second wall member provided at a position located away from and opposed to the annular first wall member in an axial direction;

a plurality of connecting pins provided in an integrally connected manner between the annular first wall member and the annular second wall member and arranged at intervals in the circumferential direction, in which one end portion of each connecting pin of the plurality of connecting pins is joined in a state of being inserted into the corresponding first attachment hole in the annular first wall member;

a plurality of variable nozzles disposed between an opposed surface of the annular first wall member and an opposed surface of the annular second wall member at intervals in the circumferential direction, each variable nozzle of the plurality of variable nozzles 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 provided on an opposite surface from the opposed surface of the annular first wall member, and integrally connected to the annular first wall member by joining of the 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 connecting pins, the pin holes being penetratingly formed so as to be aligned with the plurality of first attachment holes in the annular first wall member,

wherein a plurality of second attachment holes are penetratingly formed in the annular second wall member so as to be aligned with the plurality of first attachment holes in the annular first wall member,

wherein another end portion of each connecting pin of the plurality of connecting pins is joined in a state of being inserted into the corresponding second attachment hole in the annular second wall member, and

wherein a chamfer is formed at at least one of a rim on an axially one side of each second attachment hole of the plurality of second attachment holes in the annular second wall member and a rim on an axially other side of each first attachment hole of the plurality of first attachment holes in the annular first wall member.

6. 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 5 .