Fuel injector having a trapped volume nozzle assembly with a pressure relief valve

摘要

A fuel injector includes an injector body that defines a pressure relief passage with one end opening into a trapped volume, and a fuel pressurization chamber in fluid communication with a nozzle outlet. A needle valve member is positioned in the injector body and moveable between an inject position in which the fuel pressurization chamber is open to the nozzle outlet, and a closed position in which the nozzle outlet is blocked. The needle valve member has a closing hydraulic surface exposed to fluid pressure in the trapped volume. A pressure relief valve is positioned in the pressure relief passage, and has a valve member with an opening surface exposed to fluid pressure in the trapped volume, and a closing surface exposed to fluid pressure in the fuel pressurization chamber.