| 摘要 |
PROBLEM TO BE SOLVED: To provide a nozzle capable of suppressing fluctuation in total pressure loss of a fuel passage accompanying change in a fuel temperature and suppressing fluctuation in a fuel injection amount due to change in the fuel temperature. SOLUTION: In a fuel passage P formed as a space surrounded by a plane part 3a of a needle 3 and a guide hole 2a, a recessed part 3c recessed with respect to the fuel passage P is formed in the plane part 3a. When the flow of fuel reaches the fuel passage P, whirling is generated near an end face 3c1 of the recessed part 3c as the cross sectional area of the fuel passage P rapidly increases at the end face 3c1, so that the flow condition in the fuel passage P becomes turbulent. Thereby, the degree of change in the total pressure loss in the fuel passage P accompanying a fuel temperature rise can be made small, and fluctuation of fuel pressure near a valve part 3b of the needle 3 can be suppressed. Therefore, the occurrence of a problem in a conventional nozzle 102, namely, that the fuel injection amount is increased more as the fuel temperature rises, and the torque characteristics and exhaust components of an engine are changed, can be prevented. COPYRIGHT: (C)2009,JPO&INPIT
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