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 controller of an internal combustion engine includes processing circuitry configured to execute a peak current command value calculating process of calculating a peak current command value, which is a command value of a peak current flowing through a coil, based on a detection value of a pressure in a delivery pipe, and a peak control process of controlling a value of the peak current at the peak current command value. The in-cylinder injection valve is configured to execute multi-stage injection including a first injection and a second injection carried out at a timing toward a retarding side from the first injection. A peak current command value for the second injection is larger than the peak current command value for the first injection.

Systems and methods of controlling a solenoid coil in a solenoid valve provide a controller that allows a supervisory or leakage current to be used in a peak-and-hold driver. The controller introduces a delay time after detection of a dropout voltage that prevents the solenoid coil from being immediately re-energized in order to ensure proper dropout of the solenoid coil. The delay time imposes a wait period during which the controller takes no action with respect to the current in the solenoid coil, allowing the solenoid coil to deenergize and return the valve to its normally-open or normally-closed position. Such use of a delay time may be limited to instances where the controller has already gone through a power-up cycle such that the response time needed by the controller to energize the solenoid coil is minimized, thus reducing the valve startup time.

Various embodiments may include a method for actuating a fuel injector with a solenoid drive and a nozzle needle. The solenoid drive has a solenoid and a movable armature. The fuel injector has an idle stroke between the armature and the nozzle needle. An example method includes: applying a precharging current to the solenoid drive during a precharging phase to move the movable armature into mechanical contact with the nozzle needle; and applying a voltage pulse to the solenoid drive during a boost phase until the current intensity of the current flowing through the solenoid reaches a predetermined peak value.

A solenoid assembly includes a solenoid actuator having a core. A coil is configured to be wound at least partially around the core such that a magnetic flux () is generated when an electric current flows through the coil. An armature is configured to be movable based on the magnetic flux (). A controller has a processor and tangible, non-transitory memory on which is recorded instructions for controlling the solenoid assembly. The controller is configured to obtain a plurality of model matrices, a coil current (i.sub.1) and an eddy current (i.sub.2). The magnetic flux () is obtained based at least partially on a third model matrix (C.sub.0), the coil current (i.sub.1) and the eddy current (i.sub.2). Operation of the solenoid actuator is controlled based at least partially on the magnetic flux (). In one example, the solenoid actuator is an injector.

The magnetic coil driving circuit of the magnetic contactor according to the present invention comprises a semiconductor switch configured to open or close a circuit for magnetizing or demagnetizing a magnetic coil; a pulse width modulation unit configured to output a pulse signal as a control signal for turning on or off the semiconductor switch; a control unit configured to output a control signal for changing a pulse width of the pulse signal to the pulse width modulation unit; and a temperature detection and protection unit configured to detect a temperature inside the magnetic contactor, output an output signal for turning off the semiconductor switch when the temperature exceeds an allowable temperature, and control the semiconductor switch by the pulse signal from the pulse width modulation unit when the temperature is within the allowable temperature.

An illustrative embodiment of a fuel injector control system includes a driver that is configured to supply electrical power to a fuel injector. A controller is configured to control the driver according to a predetermined sequence of states for an injection cycle. The plurality of predefined states each include parameters for supplying electrical power to a fuel injector. Each of the states has a corresponding plurality of test parameters. At least one of the test parameters is a target parameter for the state. During each of the states, the controller determines whether at least one of the test parameters is met and determines how to control the driver for a subsequent portion of the injection cycle based on which of the test parameters is met.

Disclosed is a fuel injection control device for an engine equipped with a solenoid-type fuel injector 67. The fuel injection control device comprises: a voltage sensor SW19 configured to detect a voltage of a solenoid of the fuel injector 67; and a PCM 10 configured to set a valve-open period of the fuel injector 67, based on a fuel injection amount according to an operation state of the engine 1, and control the fuel injector 67 based on the valve-open period. The PCM 10 is configured to perform correction for gradually shortening the set valve-open period, as the voltage (residual voltage) detected by the voltage sensor SW19 when opening the fuel injector becomes larger, and control the fuel injector 67 based on the corrected valve-open period.

According to the present invention, by providing control whereby a rising slope or a descending slope of step-up current flowing to a step-up coil is detected, and corrections are made to step-up switching control, the step-up upper and lower limit current values of the step-up circuit can be controlled within intended current threshold values regardless of constant modifications or change in characteristics due to fluctuations of the battery power supply voltage or degradation of step-up circuit elements over time; heat emission by step-up circuit elements can be kept to a minimum; and the step-up recovery time can be adjusted to a constant value regardless of the slope of the step-up current.

An engine includes a fuel injector. The fuel injector includes a valve body and an electromagnetic part that moves by energizing the valve body from a valve-closed position to a valve-open position. The fuel injector injects fuel when the valve body is moved to the valve-open position. In fuel injection, an ECU feeds a pre-charge current smaller than a current for operating the valve body, to the electromagnetic part in a pre-charge period at the beginning of a start of energization, and subsequently feeds a drive current for operating the valve body, to the electromagnetic part. Further, the ECU acquires a current change parameter as a parameter correlated with a speed of a rising change in drive current, and controls the feed of the pre-charge current to the electromagnetic part of the fuel injector, based on the acquired current change parameter.