| 摘要 |
PURPOSE:To obviate the sharp rise in the temperature of burning so as to reduce the NOx-content and combustion noise in the low rotation and low load range, by providing a pilot valve in a fuel passage between a pressure chamber and a nozzle and shutting the passage for a prescribed period after the start of the fuel injection. CONSTITUTION:When the injection pressure is increased and goes beyond a prescribed point, a needle valve 12 is lifted, and a small quantity of a fuel is injected from an injection orifice 14. Then when the fuel pressure at the piston head reaches approximately the open valve pressure, a piston 72 is lifted, then after a prescribed period, since a passage 9b is closed, passages 9a, 9b are shut off, therefore the injection pressure lowers quickly, and the nozzle 10 is closed to suspend the injection. The rise in the fuel pressure in a pressure chamber 7 lifts the piston 72 further to cause it to abut against a stopper and the passages 9a, 9b are communicated. Accordingly, the fuel pressure reaches a needle chamber 11, and when the injection pressure increases, the nozzle 10 is opened to jet a large quantity of the fuel. Thus, the burning by the pilot injection is smoothly led to the main burning, and the abrupt generation of heat in the burning chamber can be obviated. |
