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

Claim 1

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 which is common to all the injection pumps 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 at will in order to initiate the variable onset of injection and further arranged to open said channel again in order to terminate the injection, said apparatus further including a control apparatus whereby pressure can be exerted via control lines upon said pressure chambers of said control slides, characterized by the following characteristics: (a) said control fuel source is embodied by said supply pump dimensioned by a control pressure (p S ) increased severalfold over the supply pressure (p V ) of said injection pumps and by a first pressure limitation valve limiting the control pressure (p S ) in a control pressure line capable of being connected with said control lines; (b) said first pressure limitation valve being correlated with a second pressure limitation valve, said second pressure limitation valve arranged to determine the supply pressure (P V ) prevailing in filling lines separate from said control lines; (c) said control apparatus comprises a valve assembly common to all of said injection pumps said assembly arranged to determine the onset and duration of pressure upon said pressure chambers of said control slide, and a distributor means separate from said valve assembly arranged to communicate with said control lines leading to said pressure chambers of said control slides said means arranged to be connected at a predetermined time to said control pressure line in synchronism with said injections and further wherein; (d) said control pressure (p S ) required for actuation of said control slides and exerted via said distributor means upon one of said pressure chambers at a time established by means of said valve assembly which blocks the discharge of control fuel out of said control pressure line into a low-pressure line and is subsequently relieved toward said low-pressure line for the purpose of effecting the return stroke of said control slide. (e) said filling lines are connected to a supply line which is under supply pressure (p V ) and which is common to all of said injection pumps; and (f) said pump work chamber can be made to communicate with said filling line by means of an overflow channel controlled by a control location provided on said control slide.