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: 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 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 process for determining the pressure prevailing in a fuel injection manifold of an internal combustion engine includes supplying the feeding pump (11) with fuel such that the injection manifold will be supplied with fuel at the feeding pressure, measuring the pressure prevailing in the injection manifold (14) with the pressure sensor (18) when the fuel is at the feeding pressure, deducing therefrom the percentage of error (e) of the pressure sensor, and memorizing this error, establishing a law of linear decrease of this error, between the feeding pressure and the lower limit of the range of maximum precision of the sensor, and deducing therefrom, for each value of pressure measured by the sensor between the feeding pressure and the lower pressure limit, the real value of the pressure of the fuel in the injection manifold, to correct the quantity of injected fuel.

Abstract: The present invention relates to a process for regenerating a fuel vapor filter for a direct injection engine, and to a corresponding device. The process according to the invention comprises the following steps, while the engine is running on stratified charge: authorizing the purging of the fuel vapor filter (18), letting the fuel vapors into at least one of the cylinders (11), and performing homogeneous combustion in the cylinder receiving the fuel vapors. The invention also relates to a corresponding device (24). This device comprises, in particular, a pump (19) allowing the fuel vapors to be circulated from the filter (18) to the cylinders (11).

Abstract: The present invention relates to a process for controlling the proper operation of an air-assisted injector (17) during the start-up phase of an internal combustion engine (11). This injector is adapted to deliver a predetermined quantity of fuel to the engine. The process according to the invention is characterized in that it comprises:a verification a posteriori, during a stabilized idle phase, that a predetermined quantity of air can be injected during the air assistance phase.The present invention also relates to a device which implements this process and is particularly applicable to the field of automotive electronics.

Abstract: A method and device for verifying the operating condition of a system for recovering vapors from a vehicle fuel tank. A vapor cartridge is insulated from the outside air and the vapor circuit of the recovery system is connected, on the one hand, to the intake port of the engine and, on the other hand, to an outlet line for the exhaust gases from the engine. The device selectively activates insulation and connection valves to sweep the cartridge with exhaust gas. Richness in oxygen of the air-fuel mixture supplied to the engine is then measured and compared with a predetermined value in order to deduce the presence of a break in the vapor circuit when the predetermined value is exceeded.

Abstract: A second spark is triggered, after a first ignition spark. The initiation overvoltage of the second spark is detected. The overvoltage and the occurrence or the non-occurrence of a failure of ignition of the air/fuel mixture prior to the second spark is deduced, according to whether the overvoltage is greater or less than a predetermined threshold voltage. Application to the protection of a chamber containing an oxidation, reduction catalyst for the exhaust gases of the engine.

Abstract: An oxygen sensor, whose output signal switches between two levels, is arranged in the gas flow leaving the catalytic converter. During regulation at a stabilized speed, the injection time suitable for ensuring stoichiometry of the air/fuel mixture is determined. During a predetermined time interval a time variation of symmetric deviation, whose amplitude and shape is predetermined about a base injection time chosen from the determined injection time, is imposed on the injection time. The base injection time used during successive time intervals is modified progressively and in a monotonic manner so as to center the deviation of the injection time on that of the oxygen storage capacity of the catalytic converter. Catalyst efficiency is evaluated from an oscillation of this signal.

Abstract: The mean oxygen richness (S.sub.o) of the exhaust gases is measured during a first engine operating phase during which the device for injection of air is active and the mean oxygen richness (S.sub.1) of the air/exhaust gases mixture is measured during a second consecutive phase during which this device is inactive and the operating condition of the device is diagnosed by comparing the difference (S.sub. -S.sub.1) in the oxygen richnesses measured during these two phases, with an expected value of this difference. Application to an engine equipped with a catalytic chamber for oxidation-reduction of the exhaust gases.