Abstract: A method for diagnosing the operation of an injector of a diesel engine of a vehicle, controlled by a plurality of control laws on the basis of at least one operating parameter of the injector for each control law. The method includes a step of measuring an operating parameter value during use of the injector, a step of determining an efficiency value of each control law on the basis of the measured value of the parameter and of a predetermined reference curve representing the efficiency of the parameter in its interval of operating values, and a step of determining an efficiency value of the injector on the basis of the efficiency value of each of the control laws.

Abstract: The subject of the present invention is a method for diagnosing the operation of an injector of a diesel engine of a vehicle controlled by a plurality of control laws on the basis of at least one injector operating parameter for each control law. The method comprises a step (E2) of measuring a value of an operating parameter during use of the injector, a step (E3) of determining a value for the effectiveness of each control law on the basis of the measured value of the parameter and of a predetermined reference curve representing the effectiveness of the parameter in its range of operating values, and a step (E4) of determining a value for the effectiveness of the injector on the basis of the effectiveness value for each of the control laws.

Abstract: A method for controlling a piezoelectric actuator of a fuel injector of an internal combustion engine of a vehicle, the actuator acting on valve elements to open or close the injector, respectively enabling or stopping the injection of fuel into a combustion chamber of the engine, includes the steps of: applying to the actuator a first nominal electric charge required to open the injector in accordance with the torque requested and the engine speed, to open the valve elements for fuel injection, instructing the closure of the injector to stop the fuel injection, by applying an electric discharge to the actuator to close the valve elements, the method applied from an on-board engine control unit during operation, and including applying to the actuator between these 2 steps at least one second electric charge to polarize the actuator during an opening phase of the injector and during fuel injection.

Abstract: Method for controlling a fuel injector with a piezoelectric actuator acting on a valve element, including the following steps, in the normal operation of the vehicle: (200): Estimating an engine parameter (PjEST), representative of an actual play (JREEL) between the piezoelectric actuator and the valve element, (300): Comparing the engine parameter with the equivalent parameter (PjECU) representative of the original play (JINIT): if the engine parameter differs from the equivalent parameter in such a way that the actual play is greater than the original play: Applying an electrical polarization charge to the piezoelectric actuator, in order to polarize the piezoelectric actuator during the injection of the fuel, Commanding the closure of the injector.

Abstract: A method for repolarizing a piezoelectric actuator associated with an injector mounted on an internal combustion engine of a vehicle, the piezoelectric actuator having undergone initial polarization before the vehicle was used, includes with the engine stopped: applying a first polarization voltage to the terminals of the piezoelectric actuator during a first specified time interval of not less than ten minutes, stopping the application of the first polarization voltage during a second time interval, following the first time interval and at least equal to the latter, applying a second polarization voltage to the terminals of the piezoelectric actuator during a third specified time interval, following the second time interval, stopping the application of the second polarization voltage to the terminals of the piezoelectric actuator after the third time interval, the successive first, second and third time intervals defining a repolarization sequence of the piezoelectric actuator.

Abstract: Disclosed is a method for monitoring a fuel injector, the injector including a piezoelectric actuator controlling a valve unit to open or close the injector, the fuel injector including an actuator play. The method includes: measuring a plurality of compensation times of the actuator play during a simulation step preceding an injection for a given plurality of fuel pressures; calculating a parameter representing the current actuator play per the measured compensation times; comparing the parameter representing the calculated current actuator play with a predetermined reference parameter of the actuator play; and transmitting a warning message if the reference parameter is exceeded; the parameter representative of the current actuator play being calculated on the basis of a polynomial function of the measured compensation times. The polynomial order of the polynomial function corresponding to the number of measured compensation times of the actuator play for different fuel pressures.

Abstract: Method for controlling a piezoelectric actuator acting on valve elements to open or close a fuel injector respectively allowing or preventing fuel injection into a combustion chamber of an engine, the method includes: applying to the piezoelectric actuator a nominal electrical charge to open the injector, as a function of the torque required and the engine speed, to open the valve elements for fuel injection, thereafter applying to the actuator at least one electrical polarization charge, to polarize the actuator during an opening phase of the injector and fuel injection into the combustion chamber, thereafter commanding the closure of the injector by applying to the actuator at least one electrical discharge to close the valve elements, the step of applying the electrical polarization charge including a prior step of increasing the value of the charge current to a value greater than that of the nominal charge.

Abstract: Method for controlling a fuel injector with a piezoelectric actuator acting on a valve element, including the following steps, in the normal operation of the vehicle: (200): Estimating an engine parameter (PjEST), representative of an actual play (JREEL) between the piezoelectric actuator and the valve element, (300): Comparing the engine parameter with the equivalent parameter (PjECU) representative of the original play (JINIT): if the engine parameter differs from the equivalent parameter in such a way that the actual play is greater than the original play: Applying an electrical polarization charge to the piezoelectric actuator, in order to polarize the piezoelectric actuator during the injection of the fuel, Commanding the closure of the injector.

Abstract: A method for determining the quantity of fuel leaving an injector of a direct-injection diesel engine, the quantity of fuel supplying a cylinder of the engine in which a piston moves, the injection of fuel being performed by a pilot injection during which a first quantity of fuel is injected into the cylinder followed by a main injection during which a second quantity of fuel, greater than the first quantity of fuel, is injected into the cylinder, the method including the following steps: a) operating the engine at idle speed, b) determining the maximum pressure in the cylinder, and c) determining, from the maximum pressure, the quantity of fuel injected into the cylinder during the pilot injection, by way of a predefined one-to-one relationship, at idle speed, between a maximum pressure value in the cylinder and a quantity of fuel injected into the cylinder during the pilot injection.

Abstract: Disclosed is a method for monitoring a fuel injector, the injector including a piezoelectric actuator controlling a valve unit to open or close the injector, the fuel injector including an actuator play. The method includes: measuring a plurality of compensation times of the actuator play during a simulation step preceding an injection for a given plurality of fuel pressures; calculating a parameter representing the current actuator play per the measured compensation times; comparing the parameter representing the calculated current actuator play with a predetermined reference parameter of the actuator play; and transmitting a warning message if the reference parameter is exceeded; the parameter representative of the current actuator play being calculated on the basis of a polynomial function of the measured compensation times. The polynomial order of the polynomial function corresponding to the number of measured compensation times of the actuator play for different fuel pressures.

Abstract: Method for controlling a piezoelectric actuator acting on valve elements to open or close a fuel injector respectively allowing or preventing fuel injection into a combustion chamber of an engine, the method includes: applying to the piezoelectric actuator a nominal electrical charge to open the injector, as a function of the torque required and the engine speed, to open the valve elements for fuel injection, thereafter applying to the actuator at least one electrical polarization charge, to polarize the actuator during an opening phase of the injector and fuel injection into the combustion chamber, thereafter commanding the closure of the injector by applying to the actuator at least one electrical discharge to close the valve elements, the step of applying the electrical polarization charge including a prior step of increasing the value of the charge current to a value greater than that of the nominal charge.

Abstract: A method for controlling a piezoelectric actuator of a fuel injector of an internal combustion engine of a vehicle, the actuator acting on valve elements to open or close the injector, respectively enabling or stopping the injection of fuel into a combustion chamber of the engine, includes the steps of: applying to the actuator a first nominal electric charge required to open the injector in accordance with the torque requested and the engine speed, to open the valve elements for fuel injection, instructing the closure of the injector to stop the fuel injection, by applying an electric discharge to the actuator to close the valve elements, the method applied from an on-board engine control unit during operation, and including applying to the actuator between these 2 steps at least one second electric charge to polarize the actuator during an opening phase of the injector and during fuel injection.

Abstract: A method for repolarizing a piezoelectric actuator associated with an injector mounted on an internal combustion engine of a vehicle, the piezoelectric actuator having undergone initial polarization before the vehicle was used, includes with the engine stopped: applying a first polarization voltage to the terminals of the piezoelectric actuator during a first specified time interval of not less than ten minutes, stopping the application of the first polarization voltage during a second time interval, following the first time interval and at least equal to the latter, applying a second polarization voltage to the terminals of the piezoelectric actuator during a third specified time interval, following the second time interval, stopping the application of the second polarization voltage to the terminals of the piezoelectric actuator after the third time interval, the successive first, second and third time intervals defining a repolarization sequence of the piezoelectric actuator.

Abstract: A method for determining the quantity of fuel leaving an injector of a direct-injection diesel engine, the quantity of fuel supplying a cylinder of the engine in which a piston moves, the injection of fuel being performed by a pilot injection during which a first quantity of fuel is injected into the cylinder followed by a main injection during which a second quantity of fuel, greater than the first quantity of fuel, is injected into the cylinder, the method including the following steps: a) operating the engine at idle speed, b) determining the maximum pressure in the cylinder, and c) determining, from the maximum pressure, the quantity of fuel injected into the cylinder during the pilot injection, by way of a predefined one-to-one relationship, at idle speed, between a maximum pressure value in the cylinder and a quantity of fuel injected into the cylinder during the pilot injection.