The present invention determines whether multi-stage injection control is operating normally or abnormally, and carries out a failsafe of multi-stage injection control as necessary. The present invention, which solves the problem described above, has means such as the following. The invention is provided with fuel injection valves provided respectively to each cylinder, an opened/closed valve detection means for detecting either one or both of an open valve state and a closed valve state of the fuel injection valves on the basis of the drive currents or drive voltages of the fuel injection valves, and a detection execution determination means for determining a detection execution time period including the detection start timing and the detection end timing of the open valve state or closed valve state; detection interference such as overlapping detection with another cylinder and overlapping of open valve detection and closed valve detection being preventable, and risks such as erroneous detection being reducible.

In a drive unit of a fuel injection device, an electric current is supplied to the fuel injection device by applying a high voltage to the fuel injection device from a high voltage source whose voltage is boosted to a voltage higher than a battery voltage at the time of opening a valve of the fuel injection device. Thereafter, the electric current supplied to the fuel injection device is lowered to a current value at which a valve element cannot be held in a valve open state by stopping the applying of the high voltage from the high voltage source. Thereafter, in a stage where a supply current is switched to a hold current, another high voltage is applied to the fuel injection device from the high voltage source.

A control apparatus, which controlling an operation of an injector provided to an internal combustion engine, includes: a voltage application unit applying a voltage raised to have a step-up target value to the injector to open the injector; a current measurement unit measuring a drive current supplied to the injector in response to an application of the voltage; and a calculator calculating a current difference value which indicates a difference between an actually-measured profile and a reference profile. The actually-measured profile indicates a time-variation in an actually-measured value of the drive current, and the reference profile is a profile set in advance. The step-up target value is corrected according to the current difference value that is calculated.

A fuel injection control system is usable with an engine, e.g., a diesel engine of a mild hybrid electric vehicle. The control system includes an auxiliary battery, a high-voltage (HV) battery, e.g., 48 VDC, a switching circuit with first and second switching pairs, a controller, and a fuel injector system. The controller opens and closes the switches to command an electrical current from the auxiliary or HV battery according to a predetermined injector current profile. The fuel injector system has one or more control solenoids. Windings of the solenoids are electrically connectable to the HV battery during a boost phase of the profile via opening of the first switching pair and closing of the second switching pair, and to the auxiliary battery during peak, by-pass, hold, and end-of-injection phases of the profile via closing of the first switching pair and opening of the second switching pair.

A booster circuit installed in a fuel injection device of an internal combustion engine, wherein malfunctions and characteristic changes of the booster circuit are detected, among which the detection distinguishes between decreases in capacity caused by deterioration or broken wires in a booster capacitor, and failures of a current monitor circuit, coil, externally connected fuel injection valve, and other components. The range of decrease in boost voltage when the fuel injection valve is opened is monitored, as is the range of increase per switch performed in order to restore the boost voltage. This makes it possible to detect malfunctions and characteristic changes of the booster circuit.

In voltage boosting circuit for performing rapid power supply to a plurality of electromagnetic coils that drive fuel-injection electromagnetic valves, an overcurrent from vehicle battery is suppressed, and continuous noise is prevented from being produced. Each of rapid-power-supply voltage boosting capacitors that are connected in parallel with each other is charged from corresponding one of a pair of induction devices, which are asynchronously on/off-magnetized by first and second voltage boosting control circuits, by way of corresponding one of charging diodes in a pair; when addition value of exciting currents for induction devices in a pair continuously exceeds predetermined value, driving modes of one of and the other one of voltage boosting control circuits are set to large-current low-frequency mode and to small-current high-frequency mode, respectively, so that on/off timing of exciting current becomes irregular even when respective inductances values of induction devices in a pair are close to each other.

A drive unit of a fuel injection device includes a driver circuit. The driver circuit opens and closes a valve element of the fuel injection device by supplying a drive current to the fuel injection device. The driver circuit supplies the drive current to open the valve element and sets the drive current to zero in an intermediate lift area. The intermediate lift area is an area is which a lift amount of the valve element is smaller than a maximum target lift amount.

A boost power supply may be constructed of a number of smaller switching power supplies, each switching power supply providing a respective portion of a combined output current provided by the boost power supply to a load. A different respective control signal may be provided to each switching power supply to regulate the respective portion of the combined output current provided by the switching power supply. Each different respective control signal may be provided to the corresponding switching power supply out of phase with respect to each other different respective control signal to prevent the combined output current from exceeding a specified threshold current value.

A fuel injection control device includes an electric controller controlling an opening and closing of an injector by energizing a coil in the injector, and a booster circuit boosting a battery voltage to generate a boost voltage. The electric controller includes a valve-opening control unit applying the boost voltage and then applying the battery voltage to the coil to execute a valve-opening control to generate a required valve-opening force, an open valve maintenance control unit applying the battery voltage to the coil to execute an open valve maintenance control to generate an open valve maintenance force and is smaller the required valve-opening force, after the valve-opening control, and a current correction control unit executing a current correction control to correct a maximum value of a current flowing through the coil when the boost voltage is applied in the valve-opening control, according to a decreasing quantity of the battery voltage.

A charging circuit for a bootstrap capacitor comprises a P MOSFET having a body diode and an N channel power MOSFET also having a body diode. The drain of the P MOSFET is coupled to the source of the N channel power MOSFET, and the source of the P MOSFET receives current from a vehicle's battery. The gate of the P MOSFET receives a control signal for turning the P MOSFET either on or off and the drain of the N channel power MOSFET is connected to a bootstrap capacitor The P MOSFET's body diode prevents current flow from the battery to the bootstrap capacitor when the P MOSFET is turned off and the N MOSFET's body diode prevents current flow from the bootstrap capacitor to the battery when the N MOSFET is turned off. The use of a power MOSFET device with its low ON resistance ensures that the capacitor is charged to a sufficiently high voltage even under low battery conditions.