Patent ID: 6976638

Claim:
In a fuel injection system for an internal combustion engine, the system comprising one high-pressure fuel pump ( 10 ) and one fuel injection valve ( 12 ) communicating with it, for each cylinder of the engine, the high-pressure fuel pump ( 10 ) having a pump piston ( 18 ) driven in a reciprocating motion by the engine and defining a pump work chamber ( 22 ), to which fuel is supplied from a fuel tank ( 24 ), the fuel injection valve ( 12 ) having a pressure chamber ( 40 ), communicating with the pump work chamber ( 22 ), and an injection valve member ( 28 ) by which at least one injection opening ( 32 ) is controlled and which is urged in an opening direction ( 29 ) on a pressure face ( 42 ), embodied on it, by the pressure prevailing in the pressure chamber ( 40 ), the injection valve member being movable counter to a closing force in the opening direction ( 29 ) to uncover the at least one injection opening ( 32 ), a first control valve ( 68 ), by which a first connection ( 66 ) of the pump work chamber ( 22 ) to a relief chamber ( 24 ) is controlled, a second control valve ( 70 ), by which a second connection ( 64 ) of a control pressure chamber ( 52 ) of the fuel injection valve and a relief chamber ( 24 ) is controlled, the control pressure chamber ( 52 ) at least indirectly having a third connection ( 62 ) to the pump work chamber ( 22 ) in which a throttle restriction ( 63 ) is located, the control pressure chamber ( 52 ) being defined by a control piston ( 50 ), which acts in a closing direction on the injection valve member ( 28 ), the control piston ( 50 ) being movable to control a flow cross section of the second connection ( 64 ) of the control pressure chamber ( 52 ) to the relief chamber ( 24 ) as a function of the stroke of the control piston ( 50 ) whereby when the injection valve member ( 28 ) is disposed in a closed position, a larger flow cross section of the second connection ( 64 ) is uncovered than when injection valve member ( 28 ) is disposed in an open position, wherein the control piston ( 50 ), when the injection valve member ( 28 ) disposed in its closed position, uncovers a primary connection ( 84 ) of large flow cross section; and wherein when the injection valve member ( 28 ) is disposed in its open position, the control piston ( 50 ) closes the primary connection, so that only a bypass connection ( 80 ; 82 ) of small flow cross section is uncovered.