Patent ID: 7128058

Claim:
A fuel injection system for an internal combustion engine comprising: an accumulator accumulating fuel in a state of a predetermined pressure; a pressure intensifier having a control chamber of which hydraulic pressure is increased or decreased when the fuel flows into or flows out and a hydraulic piston moving according to an increase or a decrease in the hydraulic pressure in the control chamber, the pressure intensifier intensifying a pressure of the fuel to be supplied from the accumulator by a pressure intensifying action of the hydraulic piston; an injection nozzle having a backpressure chamber of which hydraulic pressure is increased or decreased when the fuel flows into or flows out and a needle moving according to an increase or a decrease in the hydraulic pressure in the backpressure chamber, the injection nozzle injecting the fuel supplied by the accumulator or the fuel having pressure intensified by the pressure intensifier with a valve opening action by the needle; a hydraulic pressure supply passage supplying fuel pressure in the accumulator to the control chamber and the backpressure chamber; a hydraulic pressure release passage releasing fuel pressure in the control chamber and the backpressure chamber to a low pressure side; and a control valve provided in common in the hydraulic pressure supply passage and the hydraulic pressure release passage, and having a valve body driven by a two-position actuator and selectively opens and closes the hydraulic pressure supply passage and the hydraulic pressure release passage by the valve body to control an action of the pressure intensifier and an action of the injection nozzle, wherein the fuel injection system has two fuel passages, that are separate and distinct at least in part, that connect the control valve with the control chamber in parallel, one said fuel passage forming a portion of the hydraulic pressure supply passage and being provided with a first flow direction control means for preventing the fuel from flowing from the control chamber to the control valve, the other said fuel passage forming a portion of the hydraulic pressure release passage and being provided with a second flow direction control means for preventing the fuel from flowing from the control valve to the control chamber.