Flexible injection rate shaping device for a hydraulically-actuated fuel injector

摘要

An apparatus for variably controlling the fuel flow characteristics of a hydraulically-actuated pump injector (14) during an injection cycle. Variable control of the actuating fluid pressure and spill control of fuel from the working chamber of the pumping plunger of the pump injector work in combination. Control of the initial rate of fuel injection and also continuous or split injection throughout the engine load and speed range are provided. The actuating fluid is supplied by a pump (32) to a manifold (34) for application to the plunger when an electrically controlled valve is opened. A pressure control valve (32) varies the manifold pressure in accordance with operational parameters etc. supplied to an electric control module (40). The plunger (60) has at least one longitudinal passage (72) connected to a circumferential groove (74) which cooperates with a spill port (68) to provide the spill control. Improved flow characteristics reduce engine noise and emissions.