Fuel injection system for self-ignition internal combustion engines

Claim 1

In a fuel injection system for self-ignition internal combustion engines, in which a fuel volume to be injected is divided into a pre-injection volume and a main-injection volume, said fuel injection system comprising a line injection pump and an injection valve, with fuel being supplied from said line injection pump to said injection valve via two injection lines of different lengths, with a shorter one of said injection lines, before connecting with said injection valve, being provided with a spring-loaded first check valve, the improvement wherein: a longer one of said injection lines branching off a first distributor portion of a pressure connection of said line injection pump with a first by-pass valve, that is electrically actuatable, being connected to said distributor portion, and with both injection lines, at an down-stream end facing said injection valve, opening into a second distributor portion that is provided with connections for a second by-pass valve, that is electrically actuatable, and said injection valve, and with a second spring-loaded check valve being disposed in said second longer injection line before said second longer injection line opens into said second distributor portion, whereby said difference in length between said two injection lines and is such that a time delay is achieved between a pre-injection and a main injection due to different time requirements for a fuel pressure wave traveling said different lengths of said injection lines.