Various embodiments include a method for actuating a piezo actuator of an injection valve of a fuel injection system comprising: determining actuation signals for the piezo actuator using a stored current/voltage characteristic curve for carrying out an injection process; detecting the profile of the current flowing through the piezo actuator during the injection process and the profile of the voltage applied to the piezo actuator during the injection process; adapting the stored current/voltage characteristic curve based at least in part on the detected current profile and the detected voltage profile; and determining actuation signals for the piezo actuator using the stored, adapted current/voltage characteristic curve for carrying out a subsequent injection process.

Disclosed is a method for detecting a malfunction of a voltage-limiting circuit of a control circuit, the control circuit including an output port connected to a capacitive actuator of a motor vehicle, an output voltage on the output port being, in the absence of a malfunction of the voltage-limiting circuit, equal to or lower than a theoretical maximum value. The capacitive actuator is arranged in series with a commutator, the method including steps of: placing the commutator in an open state; activating the control circuit; measuring the output voltage over the output port; and evaluating a criterion for detecting a malfunction of the voltage-limiting circuit as a function of the output voltage.

The disclosure relates to a method for determining a drift in the static fuel flow rate of a piezoelectric injector of a motor vehicle combustion engine. The method relies on fluid-pressure measurements carried out in the injector supply chamber in order to calculate a measured static flow rate value. This value is compared against a nominal static flow rate in order to determine the existence, if any, and amplitude of the drift in the static flow rate. Furthermore, each pressure measurement is carried out when the valve of the injector is closed and the injector is open. In this way, the measured static flow rate calculation is not influenced by pressure-variation effects not relevant to the measurement.

A multi-fuel injector assembly in one embodiment includes a first fuel injector assembly to deliver a first type of fuel and a second fuel delivery system to deliver a second type of fuel. The first fuel injector includes a first nozzle, at least one first needle, and at least one first actuator configured to move the at least one first needle. The at least one first actuator moves the at least one first needle to a first fuel delivery configuration that corresponds to a first fuel mixture composition, and a second fuel delivery configuration that corresponds to a second fuel mixture composition.

Disclosed is a method for determining a static flow rate of a piezo-electric injector of an injection system. The piezo-electric injector includes a needle and a piezo-electric actuator designed to control a valve of the injector. The injection system includes an electric generator designed to send electric current pulses to the piezo-electric actuator of the injector, and a voltage sensor designed to measure voltage values at the terminals of the piezo-electric actuator. The method includes the following steps: sending during a phase of closure of the needle of an electric current pulse such that the piezo-electric actuator is positioned in contact with the valve, without giving rise to the opening thereof; measurement of a plurality of voltage values of the piezo-electric actuator; and determining a static flow rate of the piezo-electric injector on the basis of a plurality of voltage values measured of the piezo-electric actuator.

Disclosed is a method for discharging the pressure in a fuel supply rail of an injection system of an engine, the fuel injection rail connected to a fuel tank by piezo-electric injectors, each including a needle and a piezo-electric actuator pressing on a servo valve of the injector. The injection system includes a fuel pressure sensor and an electrical generator transmitting electric current pulses to each actuator. When the accelerator is released, a first electrical command allows determination of a moment of opening of the respective servo valve without triggering an injection. A second electrical command triggers a discharge of fuel from the fuel supply rail to the tank and therefore to discharge the pressure of the supply rail without triggering an injection. The second electrical command charges the piezo-electric actuator between a first voltage level that opens the servo valve, and a second voltage level triggering an injection.

The disclosure relates to a method for determining a drift in the static fuel flow rate of a piezoelectric injector of a motor vehicle combustion engine. The method relies on fluid-pressure measurements carried out in the injector supply chamber in order to calculate a measured static flow rate value. This value is compared against a nominal static flow rate in order to determine the existence, if any, and amplitude of the drift in the static flow rate. Furthermore, each pressure measurement is carried out when the valve of the injector is closed and the injector is open. In this way, the measured static flow rate calculation is not influenced by pressure-variation effects not relevant to the measurement.

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.

Disclosed is a method for detecting a malfunction of a voltage-limiting circuit of a control circuit, the control circuit including an output port connected to a capacitive actuator of a motor vehicle, an output voltage on the output port being, in the absence of a malfunction of the voltage-limiting circuit, equal to or lower than a theoretical maximum value. The capacitive actuator is arranged in series with a commutator, the method including steps of: placing the commutator in an open state; activating the control circuit; measuring the output voltage over the output port; and evaluating a criterion for detecting a malfunction of the voltage-limiting circuit as a function of the output voltage.

A fuel injector assembly in one embodiment includes a nozzle, at least one needle, and at least one actuator. The nozzle includes at least one cavity in fluid communication with nozzle openings. The at least one needle is movably disposed within the at least one cavity, and prevents flow through the nozzle openings in a closed position. The at least one actuator is configured to move the at least one needle within the cavity. The at least one actuator is configured to move the at least one needle to at least a first fuel delivery configuration and a second fuel delivery configuration. A first amount of fuel is delivered through the nozzle openings with the at least one needle in the first fuel delivery configuration, and a second amount of fuel is delivered through the nozzle openings with the at least one needle in the second fuel delivery configuration.