Diesel fuel injection system with improved starting performance

Claim 1

In a fuel injection system for a diesel engine, of the type incLuding a plunger barrel, having a radial fuel intake port, a plunger slidable axially in the barrel, a plunger operating cam having peripherally spaced lobes engageable with the plunger and operable, during one of the intake and compression strokes, to advance the plunger to a first position to block the port to inject a first quantity of fuel and then to provide for plunger retraction to free the port, the cam, at the end of the compression stroke, advancing the plunger further to a second position to block the port to inject a second quantity of the same fuel, and a switching device effective on the plunger, only during starting of the engine, to position the plunger angularly so that its peripheral surface blocks the port during advance of the plunger to the first and second positions, to effect two injections of the same fuel, and only during running of the engine, to position the plunger angularly so that its peripheral surface blocks the port, for single injection of the same fuel, only upon advance of the plunger to the second position: the improvement comprising a radial by-pass fuel intake port in said barrel in addition to said first-mentioned radial fuel intake port and at least one flow passage in said plunger connecting said peripheral surface of said plunger to the inner end face of said plunger and communicating with said by-pass fuel intake port, only during starting of the engine, in said second plunger position; there being a plurality of fuel intake ports in said barrel at different levels; and a sleeve enclosing said barrel and displaceable axially and circumferentially thereof; said sleeve having an opening therein cooperable with a selected one of said fuel intake ports.