| 摘要 |
PURPOSE:To prevent accumulation of deposit in the gap between a needle pin and the inner wall surface of a nozzle hole, by forming a tapered cut in the needle pin for increasing the opening area of a needle valve gradually with lifting of the same. CONSTITUTION:A needle pin 30 is formed with a cut 31 for increasing the opening area of a nozzle hole gradually with lifting of a needle valve 25. That is, the cylindrical needle pin 30 is cut off partially in a tapered form by an inclined surface 32 that extends axially of the pin 30 so that the gap is increased toward the lower end of the needle pin 30. Here, since the gap (m) at the cutaway portion 31 is greater than those of the conventional arrangements, it is enabled to prevent clogging of the gap (m) by carbon produced in a combustion chamber. |
