The piezo injector

To control the injection valves, the new Common-Rail injec- tors use a rapid-action actuator made of piezo crystals to control the injection valve. The piezo crystals expand within
an electrical field. The electronically controlled piezo actuator switches five times as fast as a solenoid. Bosch has built the actuator into the body of the injector. The movement of the piezo package is transmitted non-mechanically – and therefore entirely without friction – to the rapidly switching nozzle needle. This doubles the injector's switching speed, allowing a more precise measurement of the amount of fuel injected and thus leading to a reduction in harmful combustion products.