| 摘要 |
PROBLEM TO BE SOLVED: To provide a fuel injection nozzle capable of preventing fuel leakage with a simple structure, feeding spray according to an operating condition of an engine, reducing NOx, black smoke, and HC, and improving power. SOLUTION: Fuel pressure in a fuel passage hole 23 outwardly expands an inner wall of the fuel passage hole 23 in valve closing to elastically deform and radially expand a second middle diameter part 28 and make a gap 33 smaller. Leakage of high-pressure fuel to a low-pressure part is prevented by changing the gap 33 between a valve needle 2 and a nozzle body 3 according to the fuel pressure. Leakage of fuel from a group of nozzle holes 40 can be thereby prevented to reduce hazardous component in exhaust gas, and lubrication and cooling of the valve needle 2 can be made excellent to prevent generation of deposit and seizure in the fuel injection nozzle 1. Since a passage for recovering leakage fuel is not required to be formed, manufacturing cost can be reduced by simplifying the structure of the fuel injection nozzle 1 capable of making opening area of the group of nozzle holes 40 variable.
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