Fuel injection device

A fuel injection device comprising:

• a fuel injection unit having a fuel storage for storing fuel supplied from a fuel supply source, a needle for opening and closing an injection hole from which the fuel stored in the fuel storage is injected, and an injection control chamber in which fuel pressure for pushing the needle toward an injection hole side is supplied from the fuel supply source;
• and
• a pressure booster unit for increasing the pressure of the fuel stored in the fuel storage by actuation of a booster piston;
• wherein
• the needle is forced to open the injection hole by reducing the pressure of fuel in the injection control chamber to thereby inject the fuel stored in the fuel storage from the injection hole, while the needle is forced to close the injection hole by increasing the pressure of the fuel in the injection control chamber to thereby terminate injection of fuel from the injection hole;
• inflow and outflow of fuel are performed in the injection control chamber in such a manner that a flow amount of fuel flowing out from the injection control chamber during a valve-opening stroke of the needle to open the injection hole is smaller than a flow amount of fuel flowing into the injection control chamber during a valve-closing stroke of the needle to close the injection hole, and
• the pressure of fuel in the fuel storage at a time when the booster piston is actuated is regulated by adjusting the fuel pressure in the fuel supply source, to thereby enable adjustment of a fuel injection rate during the valve-opening stroke.