US Patent 10302012 Variable nozzle unit and variable geometry system turbocharger

A plurality of variable nozzles is provided at equal intervals in a circumferential direction so as to surround a turbine wheel between a facing surface of a first nozzle ring and a facing surface of a second nozzle ring. The first nozzle ring is constituted by three nozzle ring segments laminated along the axial direction. In the three nozzle ring segments, a thickness of the nozzle ring segment on a side far from the bearing housing is smaller than a thickness of the nozzle ring segment on a side close to the bearing housing.