INJECTION SYSTEM OF A FUEL INJECTION PUMP

The injection system of the present invention relates to the injection system of a fuel injection pump wherein a plunger performs a reciprocating slide motion in the axial direction inside of the plunger chamber of a barrel for compressing fuel. The plunger has a release groove connected to the plunger chamber and a control edge connected to the release groove. A spill port is formed in the wall surface of the barrel to connect the plunger chamber and a fuel supply and discharge chamber and makes contact with the control edge so that the pressure of the plunger chamber can be released. A damping groove is formed in the upper-part outer circumference of the control edge to be connected to the upper end surface of the plunger or the release groove and provides a fine fuel flow path. The damping groove meets the spill port in advance to form the fine flow of fuel from the plunger chamber to the spill port before the control edge of the plunger meets the spill port to release pressure.