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

Claim 1

A fuel injection apparatus for internal combustion engines, in particular Diesel engines, including per engine cylinder one mechanically driven pump piston of an injection pump supplied with fuel by a low pressure line from a supply pump and preferably combined with the injection nozzle to form a pump/nozzle unit, each said pump/nozzle unit having one control slide provided with a pressurized chamber actuatable by a control pressure of a source of control force counter to the force of at least one restoring spring, said control slide being inserted into an overflow line in permanent communication with a work chamber of said pump and arranged to close said overflow line in order to initiate the onset of injection and to open said line in order to terminate the injection, said apparatus further including a common control apparatus for all said injection pumps by means of which control apparatus said control pressure can be exerted via control lines upon said pressure chambers of said control slides, characterized in that said source of control force is embodied by an auxiliary pump, and further that said auxiliary pump includes an auxiliary pump piston disposed in close proximity to said mechanically driven pump piston and driven simultaneously therewith, said auxiliary pump piston having a larger diameter than said pump piston and arranged to extend into a correspondingly enlarged auxiliary pump chamber, and that said control pressure (p S ) required for actuation of said control slide can be influenced during the compression stroke of said pump piston and said auxiliary pump piston by means of a control device and that during every compression stroke of the auxiliary pump piston the control pressure (p S ) of the control fuel pumped into the pressure chamber of the associated control slide is built up by means of the control device in alternation for controlling the closing position of the control slide which triggers the onset of injection and for the return stroke of the control slide determining the end of injection which is relieved toward a fuel return and said auxiliary pump chamber and said work chamber of said pump piston are connected via filling valves connected with said low-pressure line.