| 摘要 |
PURPOSE:To reduce NOx concentration and smoke with reduction in an initial heat generation rate, by dividing a flow passage of a fuel injection pipe into a main flow passage and a sub flow passage and thereby reducing an initial injection rate. CONSTITUTION:A flow passage from A to B of a high pressure injection pipe 2 is divided into a main flow passage 15 and a sub flow passage 16. A length of the sub flow passage 16 is set smaller than that of the main flow passage 15, and a diameter of the sub flow passage 16 is set smaller than that of the main flow passage 15. A pressure wave created by movement of a plunger in an injection pump 1 is transmitted through the main flow passage 15 and the sub flow passage 16 to meet at the point B. The pressure wave transmitted through the sub flow passage 16 reaches earlier than the pressure wave transmitted through the main flow passage 15 by the time corresponding to a difference in lengths of the flow passages 15 and 16, and loses more pressure than that of the main flow passage 15 by the pressure corresponding to a difference in diameters thereof. Accordingly, a lower pressure wave in the sub flow passage 16 serves to operate an initial injection of an injection nozzle 4, thus reducing HC concentration in operation of main injection. |
