US Patent 7140353 Fuel injector with piezoelectric actuator preload

An piezoelectric actuated injector is provided which includes a nozzle valve element, a control volume, and an injection control valve including a control valve member for controlling fuel flow from the control volume so as to control nozzle valve movement. Importantly, the injector includes a preload chamber positioned along an injection control valve member for receiving high pressure fuel. The high pressure fuel acts on the injection control valve member to apply a preload force to supply a preload force to the stack of piezoelectric elements thereby ensuring more accurate control over fuel injection timing and metering.