Fuel injection system

Claim 1

In a fuel injection system having an injection distributor pump, a plurality of fuel injection valves each having a fuel injection nozzle including a nozzle opening; a conduit system arranged within each fuel injection valve and leading to said nozzle opening; and fuel supply means carrying pressurized fuel from the pump to the fuel injection valves projecting into the combustion chamber of respective cylinders of an internal combustion engine served by the fuel injection system; the improvement wherein said injection distributor pump generates a fuel delivery pressure of medium magnitude; and further wherein with each said fuel injection valve there is associated a pressure booster means for amplifying the pressure of the fuel from the value of medium magnitude to an ejection pressure required for injecting fuel by the respective fuel injection valve into the respective engine cylinder; each pressure booster means comprising a slidably supported stepped piston having oppositely oriented end faces of unlike effective areas and a return spring biasing said stepped piston in one direction; the relatively large end face of the stepped piston being in communication with said fuel supply means for exposure to said fuel delivery pressure of medium magnitude against the force of said return spring and the relatively small end face of the stepped piston being in communication with said conduit system; the improvement further comprising means defining a throughgoing axial bore in said stepped piston and a check valve disposed in said axial bore and arranged to close said axial bore in a direction opposing the force derived from the fuel pressure generated by said injection distributor pump.