Fuel injection apparatus for internal combustion engines, in particular for diesel engines

A fuel injection apparatus for internal combustion engines, in particular for Diesel engines, having per engine cylinder one mechanically driven pump piston of an injection pump and a pump work chamber in said injection pump supplied with fuel under supply pressure by a supply pump and preferably combined with an injection nozzle into a pump/nozzle unit, each apparatus having one control slide, said slide being limited by a pressure chamber and actuatable by the control pressure of a source of control fuel counter to the force of at least one restoring spring, said control slide further being inserted into a discharge channel in permanent communication with said pump work chamber and arranged to close this discharge channel in response to said control pressure in order to initiate a variable onset of injection and further arranged to open it again in order to terminate the injection, said apparatus further including a control apparatus for all the injection pumps, whereby said control pressure can be exerted via control lines upon said pressure chambers of said control slides, characterized by the following characteristics:

• (a) said control apparatus comprises a magnetic valve assembly common to all of said injection pumps and arranged to determine the onset and duration of said control pressure upon the pressure chambers of said control slides and a separate distributor apparatus, said distributor apparatus arranged to connect, said control lines of said pressure chambers in sequence with a control pressure line;
• (b) said control pressure line common to all of said injection pumps can be made to communicate with a low-pressure line by means of said magnetic valve assembly;
• (c) said control pressure (P.sub.S) required for actuation of said control slides and exerted via said distributor apparatus upon one of said pressure chambers at a time is built up by means of the magnetic valve assembly which blocks said discharge of said fuel out of the control pressure line into the low-pressure line and is subsequently relieved toward said low-pressure line for the return stroke of the control slide;
• and further wherein
• (d) said magnetic valve assembly comprises two parallel actuated, switchable, magnetic valves the first of said magnetic valves being open toward said low-pressure line before the onset of injection said first valve arranged to block the discharge of said control fuel out of said control pressure line into said low-pressure line when said second magnetic valve is already blocking fuel discharge before the onset of injection, in order to initiate the injection, and further wherein said second magnetic valve controls the termination of injection by means of its switching movement enabling said discharge, while said first magnetic valve is still in a switch-over position.