Turbocharger with vairable turbine nozzle actuated by hydraulic and mechanical spring forces

摘要

A turbocharger (100) having a variable turbine nozzle that includes an array of vanes (150) whose setting angle is adjustable by rotation of a crank shaft (180) coupled with a unison ring (170) that pivots the vanes (150). The crank shaft (180) is rotated by an actuation system made up of a piston (192) contained in a bore (144) formed in the center housing (140), and a hydraulic system for supplying pressurized hydraulic fluid to the bore (144) selectively on one side or an opposite side of the piston (192) for causing the piston (192) to move in one direction or the other. The piston (192) is connected to the crank shaft (180) by a mechanical linkage that converts reciprocating movement of the piston (192) to rotational movement of the crank shaft (180). A spring (210) is arranged between the piston (192) and a surface of the bore (144) and continuously exerts a spring force on the piston (192) toward the fully open position of the piston (192).