US Patent 7654469 Fuel injection system for an internal combustion engine

A fuel injection system having one high-pressure fuel pump and one fuel injection valve, communicating with the high-pressure fuel pump, for each cylinder of an internal combustion engine. A pump work chamber is defined by a pump piston, and the fuel injection valve has an injection valve member by which at least one injection opening is controlled. An electrically actuated control valve controls a communication of the pump work chamber with a relief region and a movable control piston acts at least indirectly in the closing direction on the injection valve member, and the control piston, on its side remote from the at least one injection valve member, is acted upon at least indirectly by the pressure prevailing in the pump work chamber. The control piston, with its side toward the injection valve member, defines a control chamber. The communication with the relief region, controlled by the control valve, discharges into the control chamber, and the control chamber communicates at least indirectly with the pump work chamber via a throttled communication.