| 摘要 |
PURPOSE:To promote atomization of fuel spray in a low load area and to prevent the occurrence of delay in injection of fuel in a high load area, by a method wherein control of a rising speed of a needle valve by means of a central plunger is effected in a low load area, and control of the rising speed of the needle valve is decreased in a high load area. CONSTITUTION:When a fuel oil pressure propagating within a fuel passage 7 exceeds a given value, a needle valve 4 is opened upward and lifted, and fuel is injected through an injection nozzle 8 of a valve body 2. When a low load area, where a push rod 5 is forced into contact with a central plunger 15 and is pushed upward as a result of an injection amount being increased, is entered, the central plunger 15 and a backup plunger 16 are integrally vertically moved through a hydraulically-operated chamber 19, and a force proportioning the pressure collecting area of the plunger 16 is exerted against a direction in which the needle valve 4 is opened. Meanwhile, when high area is entered and the fuel oil pressure of the hydraulically-operated chamber 19 exceeds a given value, a high pressure valve 24 is opened to escape a fuel oil pressure in the hydraulically-operated chamber 19 to a fuel passage 22, and this causes limitation of a force exerted against opening of the needle valve 4.
|
