The present invention provides a high-efficiency and highly-reliable fuel injection control device that controls a fuel injection valve of an internal combustion engine and can perform injection amount control in accordance with a deterioration degree of the fuel injection valve. A fuel injection control device controlling a fuel injection valve of an internal combustion engine includes a deterioration determination unit that determines a deterioration state of the fuel injection valve, an injection amount learning unit that learns the injection amount of the fuel injection valve, and a learning frequency change unit that changes the learning frequency of the injection amount learning unit in accordance with the deterioration state of the fuel injection valve.

A fuel injection control device includes an additional energization unit. Concerning an undershoot state caused by a first energization for fuel injection, a return period is an estimated period required for a movable core to return to an initial position from a first energization. An injection interval ranges from the first energization to a second energization that is for a next fuel injection. An allowable period is obtained by subtracting a rise period estimated for the second energization from the return period. The additional energization unit adds an additional energization between the first energization and the second energization when the injection interval is longer than or equal to the allowable period and is shorter than or equal to the return period.

An injection controller has a voltage applicator that applies a voltage to a driving coil of an injection valve. After a voltage is applied to the driving coil with a peak current for opening the injection valve, the voltage applicator applies a power supply voltage to the driving coil in an ON-OFF manner, to supply the driving coil with a less-than-peak current. A comparator detects whether a terminal voltage at a terminal of the coil is less than a predetermined threshold voltage. Upon detecting that the terminal voltage is less than the threshold voltage, a discharge switch applies a boosted voltage to the driving coil.

Disclosed is a method for controlling a DC-DC voltage converter for current-driving at least one fuel injector of a motor vehicle internal combustion engine. The method notably includes the steps of determining a time referred to as the “recovery” time at which the output voltage crosses the predefined high voltage threshold, of determining a time referred to as the “drop” time, corresponding to the start of injection, at which the output voltage decreases below the predefined high voltage threshold, and of calculating the time elapsed between the recovery time and the drop time.

Disclosed is a method for controlling a DC-DC voltage converter for driving with current at least one fuel injector of a motor-vehicle internal combustion engine. The method includes, when the transistor is switched from the off state to the on state, triggering a counter for measuring time, and, if at the end of a preset time called the “observation” time, the amplitude of the peak current has not reached its maximum value, steps of commanding that transistor so that the transistor switches from the on state to the off state, of keeping the transistor in the off state for a preset time called the “cooling time”, and of commanding the transistor so that the transistor switches to the on state at the end of the cooling time.

A fuel injection control device has a valve opening control portion which opens a control valve by electrically charging a piezoelectric element, and a valve closing portion which closes the control valve. The valve opening control portion includes a first rising control portion, a pause control portion and a second control portion. The first rising control portion increases a charge amount of the piezoelectric element during a first rising period. The pause control portion pauses an increase in the charge amount of the piezoelectric element during a pause period after the first rising period. The second rising control portion increases the charging amount of the piezoelectric elements again during a second rising period after the pause period. The pause period includes a period of immediately before the control valve is opened.

Provided is an electronic control device capable of always achieving a desired injector injection amount by preventing a change in injector opening time regardless of a change (a decrease) of a power supply voltage for opening a valve of an injector. A precharge current amount at the time of precharge control is changed in a stepwise manner based on a voltage of the injector valve open power supply device 10 at the time of the precharge control.

Provided is a control device of a fuel injection device which can stabilize a behavior of a valve even when a voltage of a voltage source varies, and can reduce a deviation of an injection amount. A control device 150 of a fuel injection device 101 includes a valve 214, a coil 205 which generates a magnetic attraction force to attract a movable member 202 which drives the valve 214, and a voltage source. The fuel injection device 101 applies a voltage to the coil 205 on the basis of an injection pulse, causes a drive current to flow to the coil 205 until the current becomes a maximum current to attract the movable member 202, and drives the valve 214 to inject fuel. The drive current flowing to the coil 205 or a voltage of the voltage source is detected before the injection pulse is stopped. In a case where the detected drive current or the voltage is equal to or less than a setting, a width of the injection pulse or an injection pulse different from the injection pulse is corrected to be long.

Provided is a solenoid valve drive device capable of accurately controlling a hysteresis value of a drive current for driving a solenoid valve. The solenoid valve drive device according to the present invention controls a set value of a hysteresis or a time width of the hysteresis based on a difference between an extreme value of the hysteresis in a peak hold period of a drive current and a set value of the extreme value.

An internal combustion engine control device that can ensure diagnosis of whether a fuel injection cut function normally works and that further permits startup of an internal combustion engine in a case in which the fuel injection cut function normally works is provided. To attain the internal combustion engine control system, the startup of the internal combustion engine is prohibited when carrying of a diagnostic monitoring current based on a diagnostic drive signal related to each of fuel injection valves to each of fuel injection valves in a case of transmitting a drive prohibition signal related to each of fuel injection valves to a fuel injection valve drive circuit before the startup of the internal combustion engine and transmitting the diagnostic drive signal related to each of fuel injection valves to the fuel injection valve drive circuit. By transmitting the diagnostic drive signal related to each of the fuel injection valves to the fuel injection valve drive circuit and monitoring whether the diagnostic monitoring current based on the diagnostic drive signal is carried to each of fuel injection valves, it is possible to ensure diagnosis of whether the fuel injection cut function normally works.