SPILL PORT TYPE FUEL INJECTION PUMP FOR DIESEL ENGINE

摘要

PURPOSE:To abate a combustion noise by discharging fuel in a plunger chamber back to a fuel chamber by way of an inlet port from a clearance groove in a period corresponding to an ignition delay period immediately after fuel injection starting. CONSTITUTION:In a spill port type fuel injection pump, an ignition delay period injection quantity controlling clearance groove 7 is formed in a valve surface position B little more advanced to the side of a valve opening groove 5 than a valve surface position A advanced to the side of the valve opening groove 5 as much as a portion of height of an inlet port 9 from a valve closing end edge 3 in an injection quantity regulating valve surface 4 of a plunger 2. Then, this clearance groove 7 is interconnected to a plunger chamber 13 by an interconnecting passage 6, and at the initial stage of an effective discharge stroke S of the plunger 2, fuel in the plunger chamber 13 is discharged back to a fuel chamber 14 from the clearance groove 7 via the inlet port 9 in a period corresponding to an ignition delay period (c) immediately after fuel injection starting. With this constitution, an injection quantity in the ignition delay period becomes lessened as much as a portion that a part of fuel in the plunger chamber 13 is discharged back to the fuel chamber 14, so that a combustion noise is made smaller correspondingly.