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.

The invention relates to a method for operating a piston pump, which is driven by means of a coil (1) of an electromagnet, wherein a piston (2) of the piston pump can be moved against a restoring force by means of the electromagnet, wherein a voltage (U) is applied to the coil (1) during a switch-on duration such that a current (I) flows through the coil (1) and the piston (2) is accelerated, wherein two different quenching methods are used for the current (I) in the coil (1).

An object is to suppress an inclination of a waveform indicating an injection quantity with respect to an injection pulse particularly when a lift amount of a valve body is small and an injection pulse width is short, thereby improving control accuracy of the injection quantity of a fuel injection device. Thus, a control device for controlling a fuel injection device, which includes a valve body, a solenoid, and a movable element to open the valve body, is provided with a control unit that controls a drive voltage or a drive current to be applied to the solenoid, in which the control unit controls the drive current such that the drive current to be supplied to the solenoid decreases from a maximum drive current after the maximum drive current is supplied to the solenoid and before the valve body starts to open.

A fuel injection control device first causes a first power supply unit to apply a voltage to a fuel injection valve, subsequently causes a second power supply unit to apply a voltage to the fuel injection valve, and after the first power supply unit applies the voltage, executes a lift position determination process to determine that a valve element of the fuel injection valve reaches a predetermined lift position based on a change in a drive current. A first control unit performs a drive control on the fuel injection valve without executing the lift position determination process. A second control unit executes the lift position determination process and performs a drive control on the fuel injection valve. The second control unit controls the drive current to decrease when the valve element reaches the predetermined lift position compared to a case where the first control unit performs drive control.

Methods and systems are provided for operating a lift pump of an engine fuel system. In one example, a method may comprise predicting when a fuel rail pressure will decrease below a threshold assuming that a lift pump remains off. The method may further comprise powering on the lift pump before the fuel rail pressure decreases below to the threshold to prevent fuel rail pressure from decreasing below the threshold.

Method to determine a closing instant of an electromagnetic fuel injector; in a beginning instant of the injection, a positive voltage is applied to a coil of an electromagnetic actuator so as to cause an electric current to circulate through the coil, said electric current determining the opening of an injection valve; in an end instant of the injection, a negative voltage is applied to the coil of the electromagnetic actuator so as to cancel the electric current circulating through the coil; a first voltage time development is detected at least one end of the coil of the electromagnetic actuator after the cancellation of the electric current circulating through the coil; the voltage actuation time development is compared with a voltage comparison time development; and the closing instant of the electromagnetic injector is determined based on the comparison between the voltage actuation time development and the voltage comparison time development.

A fuel injection controller includes a discharge switch that turns ON/OFF energization of a first energization path from a boost power source of a second booster circuit when a second control IC energizes a second solenoid, a first detection element that detects a value that depends on an energization state of the discharge switch, a constant current switch that turns ON/OFF energization of a second energization path from a power source voltage that outputs a lower voltage than a boost power source voltage when the second control IC energizes the second solenoid, a second element that detects a value that depends on an energization state of the constant current switch, and an energization path controller that switches energization to the second solenoid.

Method to determine an opening time of an electromagnetic fuel injector; the electromagnetic fuel injector is controlled using a series of progressively increasing energization times of the electromagnetic actuator; for each control of the electromagnetic injector, the presence or the absence of a closing of the injection valve is detected; the opening time is identified, which is equal to an intermediate value between the last energization time of the electromagnetic actuator for which the absence of a closing of the injection valve was determined and the first energization time of the electromagnetic actuator for which the presence of a closing of the injection valve was determined.

Various embodiments may include a method for adapting the opening behavior of a fuel injector having a solenoid drive, the method comprising: applying a voltage pulse having a predetermined electrical voltage to the solenoid drive; acquiring a time profile of the strength of a current flowing through the solenoid drive; comparing the acquired time profile with a reference profile; and adjusting a value of a mechanical parameter of the fuel injector to reduce a deviation between the acquired time profile of the strength of the current and the reference profile.

A fuel injection control device includes a valve closing detection unit (54) to detect a valve closing timing by using either of an electromotive force quantity detection mode and a timing detection mode, a selection unit (21) to select either of the electromotive force quantity detection mode and the timing detection mode for detecting the valve closing timing, and a correction unit (21) to calculate a correction coefficient for correcting a requested injection quantity so as to reduce the difference between an estimated injection quantity and the requested injection quantity, and the selection unit selects the electromotive force quantity detection mode regardless of the value of the requested injection quantity when the calculation of the correction coefficient is not completed.