Patent ID: 6079388
Filing Date: 2000-06-27
Classification: F02M

Abstract:
A fuel injection system comprising a fuel injection pump, a pump piston, said pump piston is driven by a cam drive provided with at least one cam and defines a pump work chamber (10) which is used to supply at least one fuel injection valve (13) with fuel injection quantities brought to injection pressure, an electrically controlled valve (24) for connecting the pump work chamber (10) of the fuel injection pump to or closed off from a discharge chamber (17) in order to control the injection, and with interruption of the injection between one pre-injection and one main injection per injection event, the at least one cam is embodied so that on a cam edge side that moves the pump piston to a feed stroke, said at least one cam has a first partial region (V) in which the pump piston executes a feed stroke to carry out a pre-injection, said at least one cam has a second partial region (P) in which after an ending of the pre-injection, the piston (1) essentially remains in a position the piston reaches at the ending of the pre-injection stroke and then, in order to execute the feed stroke for the main injection, said at least one cam has a third partial region (H), wherein the electrically controlled valve (24) is triggered so that at a low speed, the control valve is closed before the beginning of the first partial region (V) and in the first partial region (V), the valve is opened to end the pre-injection, and then, in order to execute the main injection, at a beginning of a third partial region, the valve is closed again and in this third partial region of the cam, the valve is opened again before the top dead center of the cam is reached, and that at a high speed, in order to initiate the main injection without a preceding pre-injection, the valve is closed within the second partial region (P) and is opened again within the third partial region in order to end the main injection before the top dead center is reached.