Fuel injection device

Abstract

In a fuel injection system including an injection distributor pump delivering fuel at a medium delivery pressure, a plurality of fuel injection valves each associated with a respective engine cylinder and each having a fuel injection opening for injecting fuel into its associated cylinder and a conduit leading to the injection opening, and a pressure booster associated with each valve and connected between the conduit of its associated valve and the pump for boosting the pressure at the opening from the medium pressure produced by the pump to a higher pressure required for fuel injection via the opening, the pressure booster associated with each valve being composed of a stepped piston having oppositely oriented end faces of unlike effective area, a housing in which the piston is slidably mounted and presenting a first working chamber associated with the larger end face of the piston and communicating with the pump, and a second working chamber associated with the smaller end face of the piston and communicating with the associated conduit, and a spring arrangement biasing the piston in one direction in the housing, each piston is composed of a first piston segment presenting the larger piston end face and a second piston segment separate from the first segment and presenting the smaller piston end face, the second segment presents a valve for selectively blocking communication between the conduit and the pump, and the spring arrangement is composed of two springs each acting separately on a respective one of the segments.