| 摘要 |
PURPOSE:To prevent an engine from the occurence of noises in the running region of low speed and load by providing piezo-electric elements in series with a coil spring for closing a needle valve in a fuel injection nozzle to control the valve opening pressure and lift of the needle valve with high accuracy. CONSTITUTION:When high pressure fuel is forcibly sent from a fuel injection pump 15 to a fuel injection nozzle 1 and fuel pressure reaches the valve opening pressure of a needle valve 7, the lift of the needle valve 7 is started so that a coil spring 10 is compressed through a press pin 8 to increase pressure acting on a piezo-electric element 11 and produce compressive strain and electric charge corresponding to the size of the compressive stains is generated. That charge is sent to a control circuit 20 as a voltage signal, and in the control circuit 20 the control signal voltage applied to the piezo-electric element 11 is gradually reduced. Thus, the piezo-electric element 11 gradually returns tensile strain to the initial one and the needle valve 7 is pushed up by the fuel presssure to open a nozzle hole 5 and inject fuel. |
