Fuel injection device

A fuel injection device comprising:

• a nozzle body having an injection port and movably accommodating a valve member;
• a valve portion provided in the nozzle body for opening and closing the injection port by movement of the valve member in accordance with a control signal from an engine control unit, so that a part of high pressure fuel from a fuel supply system is injected from the injection port and another part of the fuel is discharged into a fuel discharge passage, which is operatively connected to a fuel return line;
• a pressure control chamber having a flow-in port through which the high pressure fuel is supplied into the pressure control chamber, and a flow-out port through which the fuel is discharged from the pressure control chamber to the fuel discharge passage;
• a control body having a valve body and a cylinder, wherein the valve body has a pressure control surface surrounded by one end of the cylinder and exposed to the pressure control chamber, wherein the flow-in port and the flow-out port are opened at the pressure control surface, wherein one end of the valve member is movably supported in a cylindrical space of the cylinder, wherein the pressure control chamber is defined by the pressure control surface, an inner peripheral wall of the cylinder and a pressure receiving surface formed at one end of the valve member, and wherein the fuel pressure in the pressure control chamber is applied to the pressure receiving surface of the valve member so that the valve member is moved up or down depending on the fuel pressure in the pressure control chamber to thereby open or close the injection port;
• a pressure control valve provided in the fuel discharge passage for changing its valve position in accordance with the control signal, so that the flow-out port is communicated with the fuel return line or the communication between the flow-out port and the fuel return line is blocked off;
• a floating member movably accommodated in the pressure control chamber and having a press-contacting surface opposing to the pressure control surface in a moving direction of the floating member, wherein the press-contacting surface is pressed against the pressure control surface in order to block off communication between the flow-in port and the pressure control chamber as well as communication between the flow-in port and the flow-out port when the pressure control valve is operated to bring the flow-out port into communication with the fuel return line, and wherein the press-contacting surface is moved away from the pressure control surface when the pressure control valve is operated to block off the communication between the flow-out port and the fuel return line;
• a first space formed on a side of the press-contacting surface of the floating member, as a part of the pressure control chamber;
• a second space formed on the other side of the floating member opposite to the press-contacting surface, as another part of the pressure control chamber;
• a side wall portion formed at an outer side wall of the floating member;
• and
• a communication passage formed at the side wall portion for communicating the first and second spaces of the pressure control chamber with each other.