| 摘要 |
PURPOSE:To automatically adjust the valve opening pressure of a needle valve and prevent the vibration of the needle valve due to the pulsation of fuel pressure, by branching a part of injected fuel for leading the same to the pressure receiving surface of a push rod which retains one end of a needle valve spring. CONSTITUTION:Fuel fed from a fuel inlet port 8 is branched to a fuel passage 9, and is led through an upper check valve 4 and fuel passages 10, 2a to apply its fuel pressure to the lower surface of a sleeve 2 which is, therefore, pushed up by a distance (l1), overcoming a spring 14. Further, the fuel is led to the upper surface of a push rod 1 through a lower check valve 3 so that the push rod 1 is depressed. Further, when the load is gradually increased and the fuel pressure exceeds a predetermined value, the push rod 1 is depressed by a distance (l2), overcoming a needle valve spring 7, and therefore, the biasing force of the needle spring 7, or the valve opening pressure of a needle valve 11 is increased. When fuel having a high pressure greater than the valve opening pressure is fed, the needle valve 11 is opened for injecting the fuel from its injection port 18. |
