Patent ID: 7318417
Filing Date: 2008-01-15
Classification: F02M

Abstract:
1. An injection unit for an internal combustion engine, comprising a pressure reservoir for storing fuel pumped into the pressure reservoir from a fuel tank by means of a high-pressure pump, and an injector arrangement, connected to the pressure reservoir by means of a pressure line arrangement, for injecting the fuel into the internal combustion engine, wherein the injector arrangement comprises at least one servo injection valve in which both a nozzle chamber and a control chamber are supplied with fuel from the pressure reservoir via a pressure line and in which a nozzle body for opening and closing an injection passage leading from the nozzle chamber to a combustion chamber is displaceably guided, and the nozzle body is exposed at its end facing the injection passage to the pressure of the fuel in the nozzle chamber and at its opposing end to the pressure of the fuel in the control chamber, the servo injection valve is provided with a control valve for the release of fuel from the control chamber into a fuel return line leading to the fuel tank, which control valve may be operated by means of a piezoelectric actuator to cause a displacement of the nozzle body in the direction of an opening of the injection passage, for initiating an injection process by pressure reduction in the control chamber, the fuel return line is provided with a controllable valve which in an actuated state blocks the fuel flow in the fuel return line, and wherein the valve is actuated depending on predefined operating parameters of the internal combustion engine and/or the injection unit and is returned to an idle state only after expiration of a predeterminable time interval.