Fuel injector for internal combustion engine, has piezo-actuator coupled with nozzle needle and preloaded by defined preload force that acts in same direction as compressive force and is larger than compressive force

摘要

The injector has a high pressure fuel inlet (26) connected with a central high pressure fuel source and a pressure chamber (17), where the fuel is injected from the inlet into a combustion chamber of an internal combustion engine, when a nozzle needle (8) opens. The needle is coupled with a piezo-actuator (30) by a hydraulic coupler. The actuator is preloaded by a defined preload force that acts in the same direction as a compressive force and is larger than the compressive force. The compressive force acts on the actuator with a relatively low operating pressure of the coupler.