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 device includes a plurality of sound reducing parts that is operated individually, when a predetermined condition for operation is met, at each of a plurality of timings when an operating sound is generated as a result of a movement of a valve body, in one open-and-close period, and that reduces the operating sound, at each of the plurality of the timings, by changing a period of energizing an electromagnetic part to an increase side relative to a normal time, an upper limit determination part that determines whether a required period of energizing the electromagnetic part in the one open-and-close period exceeds a predetermined upper limit value, when all the plurality of the sound reducing parts are operated, and a selectively operating part that selects and operates one or more of the plurality of the sound reducing parts to an extent that the required period of energizing does not exceed the upper limit value, when the upper limit determination part has determined that the required period of energizing exceeds the upper limit value.

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 method for controlling at least one switchable valve, a brake impulse that slows down the valve movement being produced during the controlling of the at least one valve. At least one parameter of the brake impulse determines the position and/or the duration of the brake impulse. A parameter is modified, and the reaction of a measurement quantity or of a characteristic feature derived from the measurement quantity is evaluated.

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. The fuel injection device includes a valve and a coil which generates a magnetic attraction force to attract a movable element which drives the valve. A control device applies a predetermined voltage to the coil on the basis of an injection pulse, causes a drive current to flow to the coil until the drive current reaches a maximum current, drives the valve by attracting the movable element, and injects fuel. The drive current flowing to the coil is lowered from the maximum current before the valve reaches a desired maximum lift position, and a constant voltage lower than a predetermined voltage or 0 V is continuously applied to the coil until the valve reaches the desired maximum lift position.

Various embodiments include a method for adjusting an initial attenuation current for an injection valve comprising: moving a piston to a TDC; while moving the piston, closing an inlet valve; expelling the fluid; moving the piston away from TDC and applying an attenuation current to an electromagnet with the inlet valve still closed; switching a source for the attenuation current off; detecting an induction pulse resulting from an opening movement of the inlet valve by monitoring a current intensity signal of a subsequent decay in the current; adjusting a current intensity over a plurality of pump cycles to a current intensity level; checking for each current intensity level whether a time profile of the induction pulse satisfies a predetermined detention criterion; and when the detention criterion is satisfied, adjusting the current intensity level for future pump cycles to a lower current intensity level than the most recent level.

Because the relationship of the fuel injection quantity to a designated injection period differs in a half-lift region and a full-lift region, the purpose of the present invention is to bring the flow rate characteristics of an intermediate-lift region close to the flow rate characteristics of the full-lift region and improve the controllability of small fuel injection quantities. Provided are a peak current supply period in which a valve body of a fuel injection valve causes the magnetic force necessary for a valve-opening action to be generated, and a lift quantity adjustment period in which, after the peak current supply period, a current lower than the peak current is passed for a prescribed period; further provided is a current interrupt period in which a drive current is rapidly lowered before the lift quantity adjustment period.

The subject matter of this specification can be embodied in, among other things, a method for characterizing a fluid injector that includes receiving a collection of waveform data, identifying a pull locus, determining a detection threshold level value, identifying a first subset of the collection of data representative of a selected first electrical waveform of the collection of electrical waveforms, identifying an opening value, identifying a representative closing value, identifying an anchor value, identifying a second subset of the collection of data based on the collection of data, the pull locus, the first subset, and the opening value, identifying a maximum electrical value, identifying an opening locus based the collection of data, the anchor value, and the maximum electrical value, identifying a hold value, and providing characteristics associated with the fluid injector comprising the pull locus, the opening locus, the hold value, the anchor value, and the representative closing value.

A method of controlling the operation of a solenoid activated fuel injector, actuator being operated by applying a activation pulse profile to the solenoid. The method includes measuring the voltage across, or current through, the solenoid during a time period of the valve closing phase, subsequent to a valve opening phase. The method also includes determining at least one parameter from the measuring step. The method also includes controlling and varying the activation pulse profile during a subsequent activation/fueling cycle of the fuel injector based on the parameter.

A control device of a fuel injection device improves stabilization in an opening operation of a valve element and stabilizes an injection amount. The control device includes a valve element to open a fuel passage by being separated from a valve seat, a movable iron core to perform an opening/closing operation of the valve element, and a fixed iron core to attract the movable iron core when a current flows to a coil. The control device includes a control unit which performs an intermediate energization in which the coil is energized again to attract the movable iron core to the fixed iron core and then the energizing to the coil is blocked and the movable iron core is displaced in a direction away from the fixed core. The control unit controls whether the intermediate energization is performed according to an injection interval of the fuel injection device.