| 摘要 |
PURPOSE:To improve the acceleratability in a fuel injector having a first spring normally biasing a needle valve and a second spring adapted to bias the needle valve when a lift of the needle valve becomes a predetermined value or more, by forming a pressure chamber accommodating a movable member for making a set force of the second spring variable, on the back side of the second spring. CONSTITUTION:A needle valve 3 is movably provided in a lower portion of a nozzle body 2 of a fuel injection nozzle 1. A lower chamber 5 and an upper chamber 6 communicated with each other through a hole 4 are formed in the nozzle body 2. A first spring member 7 normally biasing the needle valve 3 is provided in the lower chamber 5, and a second spring member 8 adapted to bias the needle valve 3 when a lift of the needle valve 3 becomes a predetermined value or more is provided in the upper chamber 6. A pressure chamber 9 is formed in an upper portion of the nozzle body 2 on the upper side of the upper chamber 6, and a piston 12 for applying a set force to the second spring member 8 is provided in the pressure chamber 9. Thus, the pressure chamber 9 is partitioned into two chambers 13 and 14 by the piston 12. A small-diameter passage 17 as a retarding means is connected to the first chamber 13.
|
