INJECTION UNIT AND INJECTION METHOD FOR AN INTERNAL COMBUSTION ENGINE

摘要

An injection unit has an injector arrangement connected to a pressure reservoir by a pressure line arrangement The injector arrangement has at least one servo injection valve and a control valve for the release of fuel from a control chamber into a fuel return line leading to the fuel tank The Valve may be operated by a piezoelectric actuator to cause a displacement of a nozzle body in the direction of an injection passage opening for initiating an injection process by pressure reduction in the control chamber. The fuel return line has a controllable valve, which restricts the fuel flow in the fuel return line in the actuated state. It is, thus, possible to reduce the effects of a change of length of the piezoelectric actuator, which exceeds the so-called tolerance gap in the servo injection valve, which are detrimental to the operation of the injection unit.