Patent ID: 6889661

Claim:
In a fuel injection system for an internal combustion engine, having a high-pressure fuel pump ( 10 ) and a fuel injection valve ( 12 ) for a cylinder of the engine, wherein the high-pressure fuel pump ( 10 ) has a pump piston ( 18 ), driven by the engine and defining a pump work chamber ( 22 ), and having an electrically controlled valve ( 23 ) by which a connection of the pump work chamber ( 22 ) with a relief chamber ( 24 ) is controlled, the fuel injection valve ( 12 ) having an injection valve member ( 28 ) by which at least one injection opening ( 32 ) is controlled, and which is movable in an opening direction ( 29 ), counter to the force of a closing spring ( 44 ), by the pressure prevailing in a pressure chamber ( 40 ) communicating with the pump work chamber ( 22 ), the closing spring ( 44 ) being braced on one end at least indirectly on the injection valve member ( 28 ) and on the other ending at least indirectly on a displaceable storage piston ( 50 ) that is acted upon, on its side remote from the closing spring ( 44 ), by the pressure prevailing in the pump work chamber ( 22 ), the storage piston ( 50 ) being movable, beginning at an outset position, counter to the force of the closing spring ( 44 ) into a storage chamber ( 54 ), and the deflection stroke motion of the storage piston ( 50 ) into the storage chamber ( 54 ) is limited by a stop ( 53 ), and the storage piston ( 50 ) has a shaft part ( 62 ), guided in a connecting bore ( 53 ) between the storage chamber ( 54 ) and a pump work chamber ( 22 ), and a region ( 55 ), disposed in the storage chamber ( 54 ), of larger cross section than the shaft part ( 62 ), and damping of the stroke motion of the storage piston ( 50 ) is effected by means of a gap ( 68 ) existing between the shaft part ( 62 ) and the connecting bore ( 56 ), the improvement wherein the shaft part ( 62 ) of the storage piston ( 50 ) has one shaft portion ( 64 ) of smaller cross section, disposed in its outset position in the connecting bore ( 56 ), and one shaft portion ( 63 ) of larger cross section, disposed outside the connecting bore ( 56 ) toward the pump work chamber ( 22 ); and wherein in the deflection stroke motion of the storage piston ( 50 ) into the storage chamber ( 54 ), the shaft portion ( 63 ) of larger cross section dips into the connecting bore ( 56 ).