| 摘要 |
PURPOSE:To reduce the amount of emission of NOx and noise, by providing first and second passages having high and low fluid resistances from a pump chamber to a nozzle so that communication is made only through the first passages during initial fuel injection, and then communication is made through the second passages to lower the fuel injection rate at the initial stage and to raise the same during the latter half of the fuel injection. CONSTITUTION:First passages 18, 19, 22 having a large fluid resistance and including orifices 17 and second passages 16, 20, 21 having a low fluid resistance are laid in a fuel passage between a pump chamber 34 and a nozzle 30. Then, during the initial stage of fuel injection a plunger 7 closes a second port 2 so that fuel in the pump chamber 34 is injected from a first port 14 passing through the first passages 18, 19, 22 having the large fluid resistance. Thereafter, the first port 14 is closed while the second port 15 is opened so that injection is made through the second passage 16, 20, 21 having the small fluid resistance. Accordingly, the rate of fuel injection becomes high during the initial stage of fuel injection while the rate becomes high during the later half of fuel injection, thereby it is possible to attain an optimum fuel injection rate which aims at reducing NOx and noise without lowering the performance of the engine. |
