Abstract: An electronic control unit (an ECU) of a fuel injection system performs a learning injection based on a learning injection quantity and obtains multiple influence values of an operating state of an engine generated through the learning injection. The ECU calculates a learning value for correcting the injection quantity in a normal operation based on the multiple influence values. The ECU determines whether the influence value obtained during the learning injection is within a predetermined range of the influence value. The ECU calculates a provisional learning injection quantity for bringing a subsequent influence value into the predetermined range if the influence value obtained in an early stage of the obtainment is out of the predetermined range. Then, the ECU calculates the other influence values by performing the other learning injections based on the provisional learning injection quantity.

Abstract: A fuel injection control device of a diesel engine performs a learning injection during a no-injection period, in which a command injection quantity is zero or under. A difference between a variation in the engine rotation speed in the case where the learning injection is performed and a variation in the engine rotation speed in the case where the learning injection is not performed is calculated as a rotation speed increase. A torque proportional quantity is calculated by multiplying the rotation speed increase by the engine rotation speed at the time when the learning injection is performed. An injection correction value is calculated from a deviation between the actual injection quantity, which is estimated from the torque proportional quantity, and the command injection quantity. The command injection quantity is corrected based on the injection correction value.

Abstract: An electronic control unit (an ECU) of a fuel injection system performs a learning injection based on a learning injection quantity and obtains multiple influence values of an operating state of an engine generated through the learning injection. The ECU calculates a learning value for correcting the injection quantity in a normal operation based on the multiple influence values. The ECU determines whether the influence value obtained during the learning injection is within a predetermined range of the influence value. The ECU calculates a provisional learning injection quantity for bringing a subsequent influence value into the predetermined range if the influence value obtained in an early stage of the obtainment is out of the predetermined range. Then, the ECU calculates the other influence values by performing the other learning injections based on the provisional learning injection quantity.

Abstract: A fuel injection control device of a diesel engine performs a learning injection during a no-injection period, in which a command injection quantity is zero or under. A difference between a variation in the engine rotation speed in the case where the learning injection is performed and a variation in the engine rotation speed in the case where the learning injection is not performed is calculated as a rotation speed increase. A torque proportional quantity is calculated by multiplying the rotation speed increase by the engine rotation speed at the time when the learning injection is performed. An injection correction value is calculated from a deviation between the actual injection quantity, which is estimated from the torque proportional quantity, and the command injection quantity. The command injection quantity is corrected based on the injection correction value.

Abstract: In a fuel infection valve, a valve chamber of a three ways valve is selectively communicated to drain and high pressure conduits and also communicated, via a main orifice, to a control chamber for controlling valve opening and closing operations of a nozzle needle. The control chamber may be communicated via the main orifice and the valve chamber to the drain conduit or the high pressure conduit, when a valve body is driven by a piezo actuator to open or close the drain conduit and close or open the high pressure conduit. The control chamber is always communicated via a sub orifice to the high pressure conduit without bypassing the three ways valve. Accordingly, hydraulic pressure in the control chamber is slowly decreased at a valve opening time and is rapidly increased at a valve closing time so that a lift characteristic of the nozzle needle is improved.

Abstract: A fuel injection valve of a diesel engine, comprising a valve body including a concave conical surface in the tip portion of the valve body, and fuel injection holes extending from the concave surface to the outside of the valve body, and a needle valve movable in the valve body and including a cylindrical shaft portion, a first conical surface adjacent to the shaft portion and having a conical angle smaller than that of the concave surface, the lower edge of the first conical surface defining a contact line separably contacting with the concave surface, a second conical surface adjacent to the first surface and having a conical angle substantially equal to that of the concave surface, a third conical surface adjacent to the second surface and having a conical angle greater than that of the concave surface.