PIEZOELECTRIC DIRECT ACTING FUEL INJECTOR WITH HYDRAULIC LINK

摘要

A piezoelectric-actuated fuel injector for injecting fuel into a combustion chamber of an internal combustion engine is provided which includes a piezoelectric actuator movable to expand in a first direction and movable to contract in a second direction opposite the first direction, and a hydraulic link assembly disposed within a nozzle cavity formed in a nozzle housing containing a nozzle valve element. The hydraulic link assembly is positioned close to the injector orifices to minimize needle valve element length and mass, thereby reducing seat impact forces and enhance response time. A refill valve operates to move into an open position to refill a hydraulic link chamber. An actuator power source operates to vary voltage to cause multiple injection pulses and to selectively maintain the voltage above a predetermined lower level between injection pulses to maintain the refill valve in a closed position to prevent refilling of the hydraulic link chamber.