Patent ID: 8202038

Claim:
A variable geometry turbocharger, comprising: exhaust inlet walls which are provided at a nozzle at an outer side of a turbine wheel and which face each other; a plurality of nozzle vanes which are disposed between the exhaust inlet walls at a predetermined interval along a circumferential direction of the turbine wheel; a swing mechanism which rotates the plurality of nozzle vanes; and a hydraulic servo drive device which drives the swing mechanism, wherein: the hydraulic servo drive device includes a housing that has an opening at a portion thereof, a servo piston slidably housed in the housing and connected to the swing mechanism via the opening, and a pilot spool that is housed in a center hole of the servo piston and slides by pilot pressure; the housing includes a first hydraulic chamber at a first end of the servo piston and a second hydraulic chamber at a second end of the servo piston, pressure oil being flown into and out of the first hydraulic chamber and the second hydraulic chamber; the servo piston separately includes a pressure port for introducing the pressure oil from an outside into the center hole, a first piston port for intercommunicating the center hole and the first hydraulic chamber, a second piston port for intercommunicating the center hole and the second hydraulic chamber, and a return port for flowing out the pressure oil of the first and second hydraulic chambers to the outside; the pilot spool includes a switch that switches an intercommunicating state of the ports; the swing mechanism includes a driveshaft that rotates at least one of the plurality of nozzle vanes and a connector ring that transmits rotation of the at least one of the plurality of nozzle vanes to a rest of the plurality of nozzle vanes; the driveshaft and the servo piston are connected via a converter that converts advancing and retreating movement of the servo piston into rotary movement of the driveshaft; and the converter includes a slide groove formed on an outer circumference of the servo piston perpendicularly to the axial direction, a slider that slidably engages in the slide groove, and an arm having a first end rotatable engaged to the slider and a second end connected to the driveshaft.