FUEL INJECTION NOZZLE FOR DIESEL ENGINE

PURPOSE:To reduce the amount and pressure of injection in the initial period of lift and obtain comparatively quick lift characteristics in the latter period of the lift. CONSTITUTION:A part of high pressure fuel is introduced into the oil pressure chamber 29 at the back side of a free piston 27 from a high pressure fuel path 21 through a communicating path. When the amount of lift of a needle valve 14 becomes larger than DELTAl1+DELTAl2, the outer peripheral surface of the free piston 27 blocks a side hole 30a, therefore, the communicating path 30 is interrupted. According to this method, the high pressure fuel is not supplied to the oil pressure chamber 29 thereafter and the fuel is only flowed out of the oil pressure chamber 29 after being choked by an oil pressure regulating hole 34. Accordingly, the free piston 27 and the needle valve 14 are lifted comparatively quickly and arrive at the maximum lift (l). According to this method, the amount and pressure of injection may be increased in the latter period of injection.