FUEL INJECTION DEVICE

PURPOSE:To prevent the generation of secondary injection and cavitation and complete injection with a fuel valve being left as in a high pressure while improve the sharpness of its injecting action, by providing a piston, which controls the injection timing by pressing a needle valve by the hydraulic pressure of oil, in an upper part of the fuel valve while solenoid operated valves controlling supply of the hydraulic pressure oil to the piston. CONSTITUTION:A fuel valve 101 provides in its upper part a piston 115 pressing a needle valve 107 by the hydraulic pressure of oil. The hydraulic pressure oil, controlling the piston 115, is supplied from an discharged to an oil hydraulic power supply 310, separately provided from the injection system, through two solenoid operated valves 303, 304. The both solenoid operated valves 303, 304 are controlled by a trigger signal from a microcomputer in the timing set in accordance with the speed of an engine and the rack position of a fuel pump 01. The fuel pump 01 provides a check valve 08 and a check valve 11 equipping an orifice 14. In this way, the fuel valve, completing injection being left as holding a high pressure, enables poor atomization of fine particles to be eliminated.