Abstract: The invention concerns a device for injecting fuel into a diesel engine using a pulsating flow pump for improving the fuel performance of the engines by controlling the beginning and the end of the injection. It comprises a device (20) controlling the closing and opening of the nozzle needle (5) provided with a discharge circuit (21, 21′) controlled by an electrovalve (25) in branched connection between the high pressure supply conduit (7) and the low pressure return conduit (8). The discharge circuit (21, 21′) comprises a discharge valve (22) whereof the opening and the closing are slowed down by a calibrated orifice (23). The discharge valve (22) located upstream of a discharge orifice (27) provided on the return conduit (8) enables to deviate part of the non-injected fuel flow towards the nozzle needle (5) to exert thereon a closing pressure. Consequently, this results in a better control over the opening and closing of the nozzle needle (5).

Abstract: A fuel injection apparatus for controlling fuel injectors for internal combustion engines which injectors remain normally shut as a result of a high fuel pressure applied on either side of injector fuel nozzles. The apparatus of the present invention includes a first slide valve member which, by sliding from one extreme position to another, is able to lower the pressure below a fuel nozzle associated with a fuel injector to start a fuel injection cycle in that injector. The apparatus also includes a second slide valve member which, by sliding from one extreme position to another, is able to increase the pressure below the fuel nozzle to end the fuel injection cycle and control the duration of the fuel injection cycle as well as the flow rate of the injected fuel. The first and second slide valve members return to their initial positions after two consecutive fuel injection cycles.