| 摘要 |
PROBLEM TO BE SOLVED: To provide a fuel injection nozzle capable of restraining variation of injection quantity among individuals at a first step and promoting atomization of fuel spray. SOLUTION: A cylinder surface 16 is provided on a lower end of a needle 3. The cylinder surface 16 faces an entrance upper end 7a of a nozzle hole 7 along a radial direction in a lift area of the first step. A ring like clearance (a constriction part 17) formed between the cylinder surface 16 and a sheet surface 8 at the entrance upper end 7a of the nozzle hole 7 is designed to be a minimum passage area. Thus, variation of injection quantity can be prevented even if a maxim amount of lift of the first step is varied. Further, in the lift of the first step, a fuel flow coming into the entrance part of the nozzle hole 7 along the cylinder surface 16 conflicts with a fuel flow coming into the entrance part of the nozzle hole 7 from a sack chamber 9 at the entrance part of the nozzle hole 7. Therefore, the fuel flow coming into the nozzle hole 7 is disordered and atomization of the fuel spray injected from the nozzle hole 7 to an engine cylinder is promoted.
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