| 摘要 |
PURPOSE:To reduce the concentration of NOX in exhaust gas and the combustion noise by forming a cylindrical part at the base part of a shaft part and setting the sectional area of a flow passage at a specific value and setting the length between the edge of the flow passage and the top edge of the cylindrical part to a specific value. CONSTITUTION:A needle valve 12 is accommodated in slidable ways into nozzle body 11. A cylindrical part 22 is formed at the base part of a shaft part 20, and the sectional area of a flow passage 23 formed between the outer peripheral surface 22a of the cylindrical part 22 and the inner wall surface 14a of a passage part 14 is set smaller than the total area of the openings of injection holes 17. The length (h) between the upper edge 23a of the flow passage 23 on an oil reservoir 13 side and the lower edge 22b of the cylindrical part 22 is set shorter than the lift length of the needle valve 12. Therefore, the sharp combustion can be prevented, and the concentration of NOX in exhaust gas and the combustion noise can be reduced by stepwise increasing the amount of fuel injection from a fuel injection nozzle. |
