Patent ID: 6644269
Filing Date: 2003-11-11
Classification: F02D,F02M,Y02T

Abstract:
A fuel injection system comprising:a nozzle body having a nozzle hole via which fuel is injected into a cylinder of an internal combustion engine; a needle which is slidably provided in the axial direction in the nozzle body and opens and closes the nozzle hole; a control chamber for introducing a fuel pressure to a back pressure side of the needle to bias the needle in a valve closing direction; a control valve for controlling a pressure in the control chamber; means for lifting the needle in stages according to a balance among the fuel pressure which biases the needle in a valve opening direction, a biasing force of a plurality of biasing means which urge the needle in a valve closing direction, and a force of the pressure in the control chamber which biases the needle in the valve closing direction; and a fuel passage which is provided between the needle and the nozzle body and by which a rate of injection and spray conditions of a fuel to be injected are changed according to a lift of the needle, wherein the fuel passage is formed by an oblique groove formed on a conical surface of the needle facing a conical surface of the nozzle body and a passage which is formed, when the needle lifts, to increase a distance between the conical surfaces of the needle and the nozzle body so that a swirl flow rate over an entire range of lifting of the needle is continuously changed as the needle lifts; the needle includes a valve seat which seats on a conical surface of the nozzle body to close the nozzle hole; and the conical surfaces of the nozzle body respectively facing the oblique groove and the valve seat are formed in a same tapered surface of the nozzle body so that the conical surfaces have the same inclination relative to a longitudinal axis of the nozzle body.