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 present disclosure relates to the field of electromechanics. The teachings may be applied to high-pressure valves, including methods for operating a valve and with devices which are used for activating the valves. Some embodiments include methods for operating a pressure reduction valve for an accumulator injection system, wherein the valve is driven, against a return spring, with an energizable coil and armature, between a closed position and an open position. The method may include: supplying the coil with a defined electrical signal to move the armature, sensing the current intensity profile over time, and determining a movement profile for the defined current signal, including an opening or closing time, based at least in part on the current intensity profile over time.

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.

Various embodiments may include a method for operating a diesel-common-rail piezo-operated servo injector comprising: partially charging the piezo-actuator from a non-charged state at 0 V (method a); partially discharging the piezo-actuator from an already charged state to a remaining limited charge (method b); measuring the piezo-voltage with both methods and comparing the results; when the comparison demonstrates correspondence within a predefined threshold, using method b in ranges in which method a cannot be carried out; and when the comparison does not demonstrate correspondence within the predefined threshold, using method a without using method b.

Various embodiments include a method for operating an internal combustion engine with a fuel injection system including a piezo actuator comprising: stopping the discharge phase of the actuator during an injection cycle; measuring a voltage profile at the actuator; comparing a feedback signal at the actuator with a setpoint value; varying the discharge time of the actuator in successive injection cycles until the feedback signal corresponds to the setpoint value; defining a servo valve closing time as a defined offset with respect to the optimized discharge time; and using the defined servo valve closing time to set an injection quantity of fuel for future injection cycles.

An ECU includes an injection controller that performs a partial lift injection in which a fuel injection valve is drivingly opened by an injection pulse by which a lift amount of a valve body of the fuel injection valve does not reach a full lift position, a first calculation section that calculates a first parameter correlated with an amount of induced electromotive force generated by a magnetic flux change during movement of the valve body to a closed position after OFF of the injection pulse of the partial lift injection, a second calculation section that calculates, based on a time-series change of the induced electromotive force after OFF of the injection pulse of the partial lift injection, a second parameter correlated with a voltage inflection point generated with reaching of the valve body to the closed position, and a correction section that corrects a time length of the injection pulse based on the first parameter and the second parameter.

To protect a switching element to be used in a boost circuit for an in-cylinder injection type internal combustion engine or the like from damage caused by overheating without using a temperature detection element.

In a control circuit that switches a switching element between a conductive state and a non-conductive state, the switching element is controlled or a temperature of the switching element is estimated based on a potential difference between an input terminal and an output terminal of the switching element and a voltage applied to a control terminal of the switching element in the conductive state.

A method for starting an engine is provided. The method comprises in response to an engine start request, cycling a gaseous fuel injector prior to activating a starter motor. In this way, delayed engine starts using gaseous fuel may be mitigated.

The present disclosure provides a method for operating an injector of an internal combustion engine, the nozzle needle of said injector being operated by a piezo actuator by means of a servo valve. The method may include eliminating the idle travel of the piezo actuator by maintaining a permanent direct force connection between the piezo actuator and the servo valve, so that a change in force on the servo valve due to a change in pressure in the valve chamber when the servo valve is opened and closed and when the nozzle needle of the injector is closed is always transmitted to the piezo actuator as a change in force, detecting the resulting change in voltage and/or capacitance of the piezo actuator, and ascertaining parameters with which the injection quantity which is output by the injector is regulated based on the result of the detection.

An injector driving device includes a control circuit of a booster circuit that charges a capacitor by repeatedly switching a booster switch ON/OFF during a voltage boost control to cause a reverse voltage in a coil, and stops the voltage boost control upon determining that a capacitor voltage has reached a corrected target value. The control circuit detects a peak value of the capacitor voltage during an OFF period of the boost switch. The control circuit also detects a capacitor voltage as an ON value during the subsequent ON period of the booster switch. A difference between the peak voltage and the ON value of the capacitor is calculated, and a post-correction target value is set by adding the difference to a reference value of a target value.