FUEL INJECTION PUMP FOR AN INTERNAL COMBUSTION ENGINE HAVING PRE-INJECTION AND MAIN INJECTION OF FUEL

摘要

A fuel injection pump for an internal combustion engine has at least one pump piston movably disposed in a piston sleeve in a pump housing. The piston includes a first arrangement operable during a stroke in a suction direction for drawing fuel from a suction side of the pump. The piston further includes a second arrangement operable during a stroke in a delivery direction for first cutting off a connection to the suction side of the pump and then initiating delivery from a working chamber into a pressure line. The piston and piston sleeve are provided with a control arrangement which divides the fuel injection into pre-injection and main injection phases. At least one pressure limiting arrangement is provided and is associated with the working chamber. The limiting arrangement is operable during the pre-injection phase when a predetermined engine speed is reached for maintaining the pressure in the working chamber and in the pressure line at a predetermined level.