FR3034468A1 - METHOD FOR AUTOMATICALLY STARTING AN INTERNAL COMBUSTION ENGINE WITH COMMAND IGNITION - Google Patents

Abstract

A method of automatically starting an internal combustion engine, comprising steps of: controlling the energizing of an electric machine; - to impose on an air actuator a value (S1) of opening section less than a reference value (S1 '); comparing the engine speed (N) with a speed threshold (N1) and comparing a pressure (P) in the intake distributor with a threshold (P1); - To control the injection of a mass (M) of fuel and the ignition advance to a maximum value (AA1), when the speed threshold (N1) is crossed upwards by the regime (N) of the engine and that the threshold (P1) is crossed down by the pressure (P) in the intake manifold; - to cut the electric machine from the occurrence of a first combustion; - to regulate the operating parameters of the motor.

Description

The invention relates to a method for automatically starting an internal combustion engine in a motor vehicle, with a view to reducing the consumption of gasoline during the phases of the invention. BACKGROUND OF THE INVENTION starting. [0002] The evolution of environmental regulations towards lower and lower levels of pollutant emissions and greenhouse gases, as well as the increasing demand from customers for motor vehicles with reduced fuel consumption, have led to in recent years, the electrification of powertrains. These powertrains can be electrified at different levels. Thus, some of these powertrains are hybrid and include an automatic start and stop function, commonly referred to as the "Stop and Start", of the internal combustion engine, also referred to as "heat engine" in this document. The "Stop and Start" function allows the stopping and restarting of the engine of a vehicle according to predefined strategies, for example in case of prolonged stopping of the vehicle or when receiving a command from starting, following the automatic shutdown of the engine. Advantageously, such a function makes it possible to reduce fuel consumption in an urban environment. This function is particularly found in motor vehicles - "microhybrid". In these vehicles, the powertrain comprises a heat engine, as well as an automatic start and stop function, which can be performed by an electric machine, such as a starter (possibly reinforced compared to conventional starters), or an alternator -starter ; - "mild-hybrid". In these vehicles, the powertrain is equipped with an electric machine that performs better than "micro-hybrid" systems. Thus, in addition to the automatic stop and start function, the electric machine participates in the movement of the vehicle by providing an additional mechanical power to that of the heat engine during the acceleration phases, and allows, moreover, the recovery of the kinetic energy of the vehicle (via a transformation into electrical energy and then storage in batteries) during the phases of deceleration and braking; "Full-hybrid". In these vehicles, the powertrain is equipped with an electric machine that performs better than "mild-hybrid" systems. In particular, the use of higher power and energy batteries allows driving in pure electric mode, generally from 1 to 20 km, the heat engine then being cut during this phase; 10 - "full hybrid plug-in". These vehicles include, compared to full-hybrid vehicles, a battery of higher capacity, allow to store / release more power and electrical energy and propose, moreover, a connection to the electric network to recharge the battery between two rollings. It thus becomes possible, in pure electric mode, to travel distances ranging from 15 to 50 km and to reach a speed of 130 km / h. Currently, "micro-hybrid" motor vehicles have, compared to vehicles with unhybridized powertrains, fuel consumption gains of up to 20 between 15 and 20% in urban traffic. However, the automatic start and stop functions of these vehicles, have penalties in terms of electricity consumption, fuel, and emission of pollutants at each restart of the engine. Thus, during the application of a homologation cycle, such as the European ECE-EUDC driving cycle, the mass of fuel consumed during the restart phase by the automatic start and stop function, currently represents 1% of the total mass of fuel consumed over the entire cycle. This justifies the implementation of strategies to optimize the conditions of automatic shutdown of the engine, ensuring for example: stable combustion, acoustic levels and vibratory controlled, elements of decontamination initiated, a time of stopping the vehicle sufficiently long; Starting or restarting phases of the engine after stopping, for example by controlling: fuel consumption and pollutant emissions via the various organs and parameters accessible for the air loop and for combustion; the restarting quality, such as the time to reach the stabilized engine idling speed, the values of exceeding the stabilized engine idle speed (so-called "over shoot" values), the total duration of (re) start-up, and than the resulting acoustic and vibratory levels. [0007] An example of a strategy for optimizing a start function is described in document FR2797473. This document proposes a method of starting a spark ignition internal combustion engine, consisting, during a motor start command, of controlling the starting of an electric machine, and imposing on the adjustment member of intake manifold airflow and ignition advance at minimum positions. When a speed threshold of the electric machine is crossed by the top, and a pressure threshold in the inlet distributor is crossed by the bottom, fuel is then injected. The electric machine is thereafter cut off, and the operating parameters of the engine are regulated to establish its idle speed, the advance is notably increased when the engine enters an idle control phase. Such a strategy remains however perfectible in many points. It is particularly necessary, in view of current regulations, to be able to further reduce fuel consumption, pollutant emissions, as well as improve the acoustic and vibration behavior of the powertrain. It would also be particularly advantageous, after receiving a start command, to be able to reach the stabilized engine idling speed more quickly, and thus allow the vehicle to be started more quickly. A first object is to meet all of the aforementioned drawbacks. A second object is to propose a strategy optimizing the start or restart of a petrol engine with or without an automatic start and stop function, and this for any type of vehicle, hybrid or not. A third object is to reduce the fuel consumption during the start-up or restart phases. A fourth object is to improve the acoustic and vibration behavior of the powertrain. For this purpose, it is proposed, in a first aspect, an automatic starting method of an internal combustion engine controlled ignition 5 for a motor vehicle, the engine being coupled to an electric machine capable of allowing its training, the engine being connected at the inlet to an intake manifold and at the outlet to an exhaust manifold, an air actuator being arranged upstream of the intake manifold so as to regulate the flow of air through the intake manifold; ci, this method comprising steps of: upon receipt of a start command, to control the powering up of the electric machine, so as to begin the drive of the motor; when the driving of the motor starts, to impose on the air actuator a first opening section value, less than a reference value, this reference value being calculated as a function of the thermal state of the engine and being in particular able to guarantee the success of a first combustion from the occurrence of a first combustion cycle in a cylinder of the engine; Comparing the engine speed with a first speed threshold, and comparing the pressure in the intake manifold with a first pressure threshold; controlling the injection of a mass of fuel into the engine and controlling the ignition timing from a zero initial value to a maximum value, when the first speed threshold is crossed upwards by the engine speed. engine and that the first pressure threshold is crossed down by the pressure in the intake manifold; cutting the electric machine, following the occurrence of a first combustion in a cylinder of the engine; - Then regulate the engine operating parameters to converge to a set idle speed, including able to allow the establishment of engine idling speed. [0014] Advantageously, this method further comprises the steps of: - counting the number of high engine points for each cylinder of the engine and comparing this number with a predefined number; 3034468 5 when the number of Motor Point High counted reaches the preset number and in the absence of a first combustion, to impose on the air actuator the reference value for opening section, so as to achieve a first combustion in a cylinder of the engine, then to control a progressive decrease of this reference value of opening section to the first value of opening section. Advantageously, in this method, the fuel mass is injected for a duration, this duration being controlled so as to: - be kept constant at a first value when the value of the ignition advance is controlled between its initial null value and its maximum value; progressively decrease from the first value to a second value corresponding to the injection duration applied for the engine idle speed, as soon as the value of the ignition advance has reached its maximum value. Advantageously, in this method, the fuel mass is injected at a constant value from the start of its injection to the occurrence of a first combustion in a cylinder of the engine. Advantageously, in this method, between a moment of occurrence of a first combustion in a cylinder of the engine and a moment of crossing up the idle speed set point by the engine speed, the value of the section of the engine. opening of the air actuator is progressively controlled to a second opening section value less than the first opening section value; the injected fuel mass is gradually increased until reaching a maximum value. Advantageously, in this process, as soon as the maximum value of fuel mass is reached, the mass of fuel is controlled so as to progressively converge towards a lower value, this lower value corresponding to the mass of fuel injected during idle speed of the engine. Advantageously, in this process, when a second pressure threshold, lower than the first pressure threshold, is crossed down by the pressure in the intake distributor, the opening section value of the the air actuator is progressively controlled to a third opening section value smaller than the second opening section value; the value of the ignition advance is progressively controlled from its maximum value to a second value less than the maximum value. Advantageously, this method comprises detecting a control phase of the engine idling speed by comparing the engine speed with a set value 10 crossed downwards; the progressive control of the ignition advance towards a final value, lower than the second value, as soon as the occurrence of the regulation phase of the engine idling speed is detected. It is proposed, according to a second aspect, a computer equipping a motor vehicle, configured to apply the automatic starting method of an engine summarized above. Other objects and advantages of the invention will become apparent in the light of the description of embodiments, given below with reference to the accompanying drawings in which: FIG. 1 illustrates a motor vehicle comprising a motor and a computer programmed to regulate operating parameters of an engine according to various embodiments; FIG. 2 illustrates the regulation of an opening value of the air actuator of an intake manifold of an engine according to various embodiments; FIG. 3 illustrates the regulation of operating parameters of an engine according to various embodiments. In Figure 1 is shown a vehicle 100 automobile comprising a spark ignition internal combustion engine 1 (designation referring to the combustion that characterizes it) or more commonly called engine 1 gasoline. The engine 1 comprises at least one cylinder defining a combustion chamber, which is associated in an upper portion with an ignition device, such as a spark plug, to produce the spark necessary for the combustion of an air / fuel mixture. fuel. The cylinder is on the one hand associated with an intake valve which controls an air intake or air / fuel mixture inside the combustion chamber, and on the other hand, a valve of exhaust which controls an exhaust, out of the combustion chamber, of exhaust gas from the combustion of the air / fuel mixture. Each cylinder of the engine 1 is connected to the inlet distributor 5 and the exhaust manifold, respectively via an intake manifold and an exhaust manifold, allowing the admission of air or the air / fuel mixture and exhaust of the combustion gases through each cylinder. The exhaust manifold is, for its part, connected to a catalyst for which are arranged upstream and downstream of the probes for determining the flow of air through and the mass of oxygen present in the latter. . In the case of an indirect injection engine, the fuel mass is injected by injectors into the intake manifolds, whereas in the case of a direct injection the fuel mass is directly injected into each cylinder. Furthermore, an air actuator, such as a motorized throttle valve, is arranged upstream of the intake distributor of the engine 1 so as to regulate the flow of air through it, and therefore the mass of circulating air to the different cylinders of the engine 1. The spark ignition engine 1 is controlled by a computer 2 20 (also called engine control), the computer 2 being programmed to best meet the will of the driver, retransmitted including via a accelerator pedal. Thus, the computer 2 receives various information, and in particular that from a sensor positioned on the accelerator pedal, this information allowing it to control in particular the operating speed of the engine 1. The engine 1 spark ignition operates according to a four-stroke cycle defined in the following order: an intake, a compression at the end of which take place the ignition and the combustion of the air / fuel mixture, a relaxation and an escape. The work produced by the spark ignition engine 1 comes from the combustion, initiated by the ignition device of the air / fuel mixture compressed within the cylinder by an alternately moving piston, between an extreme high position. and an extreme low position, relative to the cylinder, respectively referred to as High Dead Point (TDC) position and Low Dead Point (TDC) position. The reciprocating movement of the piston allows rotation of a crankshaft via a connecting rod connecting the piston to the crankshaft, the movement of the crankshaft being then transmitted to the wheels via different mechanisms. During an engine cycle, ignition of the air / fuel mixture, via the ignition device, occurs upstream of the piston position PMH at the end of the compression phase. In order to calibrate the ignition, the engine manufacturers define a parameter called "ignition advance" corresponding to an angular difference (expressed for example in degrees), having for reference the crankshaft, between the moment of ignition and the ignition. moment of the piston passage to the top dead center (TDC) position, the top dead center position (TDC) of the piston corresponding to the reference position. Advantageously, the computer 2 is connected with different sensors that provide real-time data on the automobile vehicle 100, and in particular on the engine 1. Among these data, there are 15 including: the engine speed N: it corresponds to the number of rotation performed by the engine 1, and more precisely by the crankshaft, per unit of time. It is generally expressed in rpm and is measured by a rotational speed sensor; The engine temperature: it corresponds to the temperature of the coolant (for example a water / antifreeze mixture), or the temperature of the lubricating oil at the cylinder, or the temperature of the material of a sensitive constituent; engine 1 (eg an area of the cylinder head). It is generally measured by a temperature probe; the position of the accelerator: it corresponds to the level of depression of the accelerator pedal, this depression being generally measured by a position sensor on the accelerator pedal; the pressure P in the intake manifold: it corresponds to the pressure of the air in this unit, the latter being measured by a sensor placed in the intake manifold; the air flow through the catalyst and the oxygen content in the catalyst: they are measured by the probes placed upstream and downstream of the catalyst, and allow the calculator 2 to evaluate the mass of oxygen stored in the catalyst; the catalyst. An electric machine is, moreover, coupled to the engine 1 in order to allow its drive and its rotation when receiving a start command or restart by the computer 2. A start command is by way of example, generated when the ignition key is actuated or by pressing a start button. A restart command is, for example, generated when the brake pedal is released, when the accelerator pedal is depressed or when the clutch pedal is depressed, or when the lever position is changed. gear change, following a stop of the vehicle 100 automobile. The electric machine is, for example, a starter or an alternator-starter. In the latter case, the electric machine supplies electrical energy to different electrical consumers of the automobile vehicle 100 (for example: pumps, compressors, sensors, actuators) once the start-up process 15 has been finalized. All or part of these consumers can also be powered electrically by an external power source, independent of the alternator-starter, such as a high or low voltage electric battery. [0031] Advantageously, thanks to feedback from the various sensors, the computer 2 develops and controls control strategies of the engine 1, in particular via the generation of control signals controlling the injection (for example: mass of fuel injected, duration of the injection); the generation of control signals controlling the starting or stopping of the electric machine driving the motor 1 during start-up; generating control signals controlling each ignition device, for independently controlling the ignition of each cylinder, and therefore the ignition timing; The generation of control signals controlling the air actuator (for example: motorized throttle valve) upstream of the intake distributor, thus allowing the regulation of the air pressure in this member. FIG. 2 shows, by way of example, two diagrams a), b), each showing on the ordinate the evolution of the opening section S (also called the passage section) of the actuator of FIG. intake manifold air, driven by the computer 2, as a function of the time t on the abscissa. The diagram a) illustrates the state of the art for the sake of understanding, while the diagram b) illustrates exemplary embodiments, having various advantages with respect to this state of the art. With reference to diagram a), at a time t0, the computer 25 receives a start command, and then controls the drive of the motor 1 by the electric machine. The calculator 2 furthermore calculates, at this instant, an opening value / section for the air actuator, such as an effective passage section in degrees or in square millimeters, in order to regulate the flow of air entering towards the air actuator. intake distributor and the different engine cylinders 1. In the state of the art, this value is a reference value Si ', able to guarantee the success of a first combustion from the occurrence of a first cycle in combustion in a cylinder of the engine 1. The value Si 'referential is a value calculated in particular according to the thermal state of the engine 1 and the depression of the accelerator pedal, 15 and can therefore vary depending on the engines . Likewise, depending on the temperature of the engine 1, and on the nature of the fuel (for example: alcohol content in gasoline), the computer 2 determines a period T of application for this reference value Si '. Generally, the calculation of the value Si referential by the computer 2 is based on the information provided by the various sensors, mathematical models and / or prerecorded measurement tables, and takes into account for its calculation: the calculation of a value (arrow 21) for opening the air actuator (throttle passage section) to compensate for overall engine losses, for example friction; The calculation of a value (arrow 22) for opening the air actuator making it possible to generate a reserve of torque. Such a torque reserve generally takes into account, during its calculation, the torque taken by each electrical consumer, as well as a torque to ensure the takeoff of the vehicle 100 automobile; The calculation of a value (arrow 23) of opening of the air actuator allowing the realization of the High Pressure Indicated Middle Torque, commonly referred to by the acronym CMI HP, the latter being a function of the speed N of the engine 1 and the position of the accelerator pedal; the calculation of a value (arrow 24) for opening correction of the air actuator, as a function of the thermal state of the engine 1. This value is determined by the computer 2 for parameters 3034468 11 of injections (eg injection time / injection time, ignition advance value) and air circulation management (throttle opening, air volume in the intake manifold), these operation of the engine 1 being fixed during an open loop phase 5 by the computer 2. The open loop here corresponds to a period during the start of the vehicle 100, for which the parameters of injection and traffic management air do not self-regulate between them: the computer 2 sends setpoint values, and the results obtained via the application of these instructions, do not affect the control strategy in the next time step. In contrast, during a subsequent closed-loop phase, the computer 2 jointly takes into account the results obtained via the application of the different operating parameters of the engine 1, in order to compute at the time step following the values of these parameters; The calculation of a compensation value (arrow 25), commonly referred to as the "offset" anglicism, for opening the air actuator according to the thermal state of the engine 1. [0034] on the diagram a) representing the state of the art, the reference value Si 'is controlled by the computer 2 as the opening section 20 of the air actuator during the predetermined period T. Advantageously, the period T is determined so as to cover the occurrence of a first combustion (not shown), as well as the instant ti where the motor 1 rotates autonomously, that is to say without training the electric machine, which is then cut. At the end of this period T, the opening compensation value (arrow 25) of the air actuator is then progressively reduced (arrow 26) to a second value S2, corresponding to a cancellation of this offset. Commonly, the progressive reduction of the offset is determined by the computer 2 as a function of the thermal state of the engine 1. The opening section S 30 of the air actuator is then kept constant at the second value S 2, up to a predetermined time you start from the transition from the open loop command of the injection parameters and the management of the air flow, to a closed-loop management of these parameters made from a predetermined moment tiii.

Thus, between times t i and t i, the computer 2 progressively reduces the opening section of the air actuator to a third value S 3 which relates to an opening of the air actuator in the operating mode. stabilized idle. At time tiii, the parameters are then regulated in a closed loop by the computer 2 in order to converge towards the stabilized engine idling speed. The stabilized engine idling speed is, for example, determined by the computer 2 during start-up as a function of the engine 1 thermal, and the vehicle stopping time 100. Thus, according to various modes of embodiment, the computer 2 calculates a set point N3 of idle speed, able to allow the establishment of the idling speed of the engine 1, by estimating the mass of oxygen present in the catalyst connected to the exhaust manifold at the output of the engine 1. Such an estimate by the computer 2 takes into account, in particular, the calculation of the fuel injection duration during the start-up or restart phase. For example, at each start, the computer 2 makes an estimate of the mass of oxygen, as soon as the probes placed upstream and downstream of the catalyst have operating conditions in accordance with preconfigured thresholds (for example: voltages, temperatures). As the oxygen mass is initially set to a default value, this value is then updated according to whether the engine is running or stopped. In the case of a rotating motor 1, the mass of oxygen stored in the catalyst is calculated from the integral of the cylinder air flow rate converted by the oxygen mass calculator 2. This flow rate is then weighted by a multiplicative factor, calculated according to the state of the probes. Advantageously, this makes it possible to identify the different transitions of rich / poor or poor / rich mixtures at the level of the catalyst, to deduce the evolution of the oxygen mass. In stop phase, the last oxygen mass value in the catalyst is stored in memory. Thus, in the case of a stationary engine, the mass of oxygen stored in the catalyst is calculated from the last updated value in the rotating motor phase 1, weighted by a configurable offset value. The duration of fuel injection during the start-up or automatic restart phase ("Stop and Start" function) is then adjusted by the computer 2, via a factor calculated as a function of the estimated mass of oxygen in the catalyst, the the speed N of the engine 1, its thermal state 35 (for example: temperature of the coolant, lubricating oil, intake air), atmospheric pressure and time spent at a standstill . It is also observed, in the diagram a) of Figure 2, at time tiii a value (arrow 27) of residual opening of the air actuator 5 relative to the third value S3. The amplitude of this arrow 27 is here given by way of purely illustrative example. This residual value tends generally to zero, and is calculated in such a way as to anticipate the difference in dynamic behavior between the injection parameters and the air flow management parameters in the engine 1. [0037] Referring now , in diagram b) of FIG. 2, in a first embodiment illustrated in solid line, at the instant t0, when receiving a start command, the computer 2 calculates the value Si 'referential, and imposes then to the air actuator a first opening value Si, reduced compared to the value Si 'referential.

Advantageously, this first value Si of reduced opening is determined, in particular, as a function of the depression of the accelerator pedal, the thermal state of the engine 1 (for example: temperature of the coolant), and the torque sampling of the various consumers (for example: alternator, injection pump, air conditioning compressor). Thus, in this diagram, the first value Si of reduced opening, can be seen as a value (arrow 28) offset offset from the value (arrow 25 dashed fine line) of the opening offset of the 'air actuator calculated for the value Si' referential. By way of example, the opening angle of the air actuator is reduced compared with the reference value S 1 'by a value of between one and four degrees. The aerodynamics of the air are therefore temporarily degraded in the intake distributor and in the various cylinders. Advantageously, this accelerates the depression of the intake manifold. The first value Si of reduced opening is then kept constant during preferentially the same period T determined for the state of the art of the diagram a). Alternatively, this period T can be reduced. In one embodiment, when the heat engine is in the automatic stop phase by the "Stop and Start" function, a first specific change in the opening angle of the air actuator is performed, during the next restart of the engine 1, according to the evolution 3034468 14 of the engine speed. When the heat engine is in the stop phase by the ignition key, a second specific change in the opening angle of the air actuator is performed, at the next start of the engine 1, depending on the evolution of the engine speed. Thus, in this embodiment, these changes in the opening angle of the air actuator are different depending on the situation: restart after an automatic stop phase and start or restart by the ignition key. [0040] In another embodiment, for the 100 flex-fuel vehicles, a negative offset is also added during the start-up phase, and then progressively reduced to 0 when the engine runs autonomously (after obtaining a first combustion), in order to avoid any risk of stalling the engine I. In another embodiment, illustrated in thick dashed lines on the same diagram, the calculator 2 calculates an instant tiv, occurring during the predetermined period T, this instant corresponding to a predetermined number of High Dead Point TDC (or a predetermined number of engine times), for which a first combustion has not yet been realized with the first S1 reduced opening value. By way of example, the computer 2 counts the number of high engine points for each cylinder of the engine 1 and compares this number with a predefined number (configurable). In order to guarantee this first combustion during the period T, the computer 2 then applies, from the instant tiv, an offset value (arrow 29), in order to bring the opening value of the air actuator the first value S1 of opening reduced to the value S1 'referential. At the instant ti, when the motor 1 turns autonomously, the computer 2 then decreases progressively (dashed slope 30) the opening of the air actuator from the value S1 'referential to the first value S1 of opening reduced, and if it is reached before the end of the predetermined period T, maintains it until the end of this period T. [0042] The various embodiments of the diagram b) then follow the same strategy driven by the computer 2 (common curve solid line from the end of the predetermined period T). At the end of the predetermined period T, the computer 2 progressively reduces (arrow 31) the opening section of the air actuator, from the first value S1, until reaching the second value S2. This progressive reduction is determined by the computer 2 as a function of the thermal state of the engine 1.

The opening section S of the air actuator is then kept constant at the second value S2, until a predetermined time T ''. From this moment on, the transition of the open-loop control of the operating parameters of the engine 1 (injection and air flow management parameters) to a closed-loop control of these parameters begins, effective from a predetermined time tiii '. For this time tiii ', the opening section S is then at the third value S3 relating to an opening of the air actuator in stabilized idle mode. Thus, between moments t1 'and tiii', the calculator 10 2 progressively reduces (as a function of the temperature of the engine 1) the opening value of the air actuator from the second value S2 to the third value S3. relating to the opening of the air actuator in stabilized idle mode. At time tiii ', the operating parameters of the engine 1 are then regulated in a closed loop by the computer 2: these parameters 15 then converge to values ensuring the stabilized engine idling speed. Moreover, for illustrative purposes, there is still here, by way of example, a value (arrow 27) of residual opening of the air actuator with respect to the third value S3 at time tiii '. The embodiments described in the diagram b) have several advantages over the state of the art. First, the first value Si being reduced compared to the reference value Si '. This accelerates the depression of the intake manifold. This makes it possible to advance the open-loop control transition time of the operating parameters of the engine 1 (for example: parameters for injection and management of the air flow) towards a closed loop regulation, and thus also get an early closed-loop loopback. We thus note on the diagram b) that the moment you are advanced compared to the instant you, so for the moment tiii 'with respect to the instant tiii. It is therefore faster to return to the engine idle speed control phase, compared to the state of the art, which therefore reduces the total startup time. In addition, the acceleration of the intake manifold depression contributes to reducing the fuel consumption associated with starting or restarting. Next, the dotted-line embodiment (increasing the offset to the reference value Si) is not limited to detecting and mitigating a simple late combustion beyond a predetermined number of High Engine Point. This number 3034468 16 is indeed parameterizable and takes into account parameters such as the type of start-up of the vehicle 100 (eg: automatic start via the "Stop and Start" function, key start, key restart), its altitude (by example: atmospheric pressure, pressure in the inlet distributor), or the thermal state of the engine 1. Thus, if a start is not possible with the first value Si, the computer 2 is able to anticipate the In fact, this start will not occur either at a given number of High Motor Point, and it will precautionarily increase this value towards the value Si referential, in order to ensure a first combustion in a cylinder of the engine 1. The computer 2 n Therefore, not necessarily the occurrence of this determined number of High Dead Point (or engine time) in the cylinders of the engine 1. For example, depending on the external conditions (pressures, temperatures), the The calculator 2 can anticipate the fact that at the instant ti, that is to say after a predefined number of Top Dead Center (TDC), the application of the first value Si will not allow to reach a first combustion. In this case, it can apply from the time of start T0 the value Si 'referential, it then decreases gradually (depending on the thermal motor 1) to the first value Si reduced as soon as the engine 1 rotates so autonomous. Therefore, thanks to this preventive action, it is ensured that the engine 1 is started under all pressure, altitude and temperature conditions, while ensuring a shorter start-up time compared to the state of the art. According to another strategy, the number of High Dead Point (TDC) being configurable, one can also voluntarily choose to delay the moment of first combustion of one or two High Motor Point. Although the start of the thermal engine 1 is then delayed, such a delay remains imperceptible to the driver and allows the establishment of better starting conditions: optimization of the engine speed, the air pressure in the distributor d inlet, pressure and temperature in the combustion chamber. Advantageously, this contributes to improving the vibratory conditions (shaking of the engine 1) during successive starts or restarts, these conditions being perceptible by the driver. The comfort of the latter is therefore improved. [0044] In parallel with the control of the opening section S of the air actuator, the computer 2 controls various operating parameters of the engine 1, such as the value of the ignition advance and the ignition speed. the injection parameters (fuel mass injected, injection time). As will now be seen in FIG. 3, these parameters are notably regulated by the computer 2 as a function of the air pressure in the intake distributor (or in the combustion chambers), as well as the engine speed. In FIG. 3, there are seven diagrams showing one for the same abscissa scale, temporal evolutions of different operating parameters of the engine 1: the diagram a) illustrates on the ordinate the engine speed N 1 in 10 as a function of the time t on the abscissa, during a start-up (or restart) phase of the engine 1; b) illustrates on the ordinate the binary state E of the electrical machine as a function of the time t on the abscissa, during a start-up (or restart) phase of the motor 1; - Diagram c) shows the ordinate pressure P in the inlet manifold (or in the combustion chambers) as a function of time t abscissa, during a start phase (or restart) of the engine 1; Diagram d) illustrates, on the ordinate, the opening section S, also called the passage section, of the air actuator (eg butterfly) as a function of the time t on the abscissa during a start-up phase (or restart) of the engine 1; the diagram e) illustrates on the ordinate the value of the ignition advance AA as a function of the time t on the abscissa, during a start phase 25 (or restart) of the motor 1; the diagram f) shows on the ordinate the fuel injection duration D as a function of the time t on the abscissa, during a start-up (or restart) phase of the engine 1; the diagram g) shows on the ordinate the mass M of fuel injected 30 as a function of the time t on the abscissa, during a start-up (or restart) phase of the engine 1. [0046] On the diagrams of this FIG. Embodiments are illustrated in solid thick lines, or thick dashed lines. The state of the art is illustrated in mixed fine lines, in order to observe the advantages of the embodiments with respect to it. At the instant t0, the computer 2 receives a start command (or restart), and then controls the drive of the motor 1 by the electric machine. The start command is, for example, performed following a driver action taken into account by the computer 2: via the ignition key, by pressing a start button, a release of the brake pedal, a depression of the clutch pedal, a passage of the first gear, or a depression of the accelerator pedal. The engine speed N is then zero, the electric machine is turned on but does not operate again (binary state E at "0"). The pressure P in the intake manifold is equal to a value of atmospheric pressure PO outside the vehicle 100, the opening section S of the air actuator is at a value SO of rest taken when the engine 1 is at the stop (here, in the open position as positive value) and the ignition advance AA is zero. At this time, the fuel injection has not yet started, the values of injection duration D as well as mass M of fuel injected are therefore zero. At time tl, the electric machine is started, in starter mode, to drive the engine 1: its binary state E therefore passes to the value "1". Immediately following this instant t1, the electric machine 20 drives in rotation the thermal motor 1, which therefore sees its regime N increase. The setting in motion of the internal organs of the engine 1 (rotation of the crankshaft, distribution, translation of the pistons and the valves) then causes a depression of the air in the intake manifold: the pressure P of the air in the It begins to decrease.

The air actuator adopts a position such that its opening section is at the first value Si, lower than the reference value Si 'previously determined by the computer 2. The other operating parameters of the engine 1 remain, as for they, unchanged. At time t2, the motor is still driven via the electric machine 30 (in starter mode), the speed N of the heat engine then reaches upwards (that is to say from below) a first known speed threshold Ni (preconfigured) of the computer 2. By way of example, the computer 2 determines the achievement of the first threshold Ni by comparison with the current value of the speed N of the engine 1. Meanwhile, the pressure P in the 35 intake manifold continues to decrease. This pressure value P is, in addition, compared by the computer 2 with a first threshold 3034468 19 P1 of predefined pressure, known thereof. In the example illustrated in the diagram c), this first pressure threshold P1 is here not yet reached downwards (that is to say from above). However, in another example, this first pressure threshold P1 can be reached before reaching the first threshold Ni. Here, at time t2, the electric machine remains in operating state (binary state E at "1") in starter mode, and the speed N of the motor 1 therefore continues to increase. The other operating parameters of the engine 1 (position of the air actuator, zero injection) are controlled by the computer 2 so as to remain unchanged. The computer 2 makes sure, in fact, to keep these parameters constant, as long as it does not detect that the thresholds Ni of regime and P1 of pressure are both reached. At time t3, the electric machine drives at its maximum rotational speed the engine 1. The engine 1 thus reaches a second speed threshold N2 15, referring to the maximum speed of the electric machine according to the gear ratio. of rotation between the electric machine and the motor 1. The engine 1, under the drive of the electric machine, and in the absence of first combustion, therefore remains driven constantly to this second threshold N2. At this time, the pressure P in the intake manifold continues to decrease, but does not yet reach the first pressure threshold P1. Once again, the other operating parameters of the engine 1 (position of the air actuator, zero injection) are controlled by the computer 2 so as to remain unchanged. At time t4, the pressure P in the inlet manifold 25 continues to decrease and reaches down the threshold P1 pressure. The achievement of the first threshold Ni engine speed has already occurred (here at time t2), the electric machine is maintained in operation in starter mode and the computer 2 then controls the fuel injection: by direct or indirect injection via intake manifolds according to the structure of the engine 1. More specifically, the computer 2 controls: the injection of a mass M1 of fuel into the engine 1 for a duration D1; the ignition advance AA from its zero initial value to a maximum value AA1.

The computer 2 also maintains the passage section S (i.e., the opening) the air actuator at the first value Si. In one embodiment, if a first combustion does not occur. is still not detected after a predefined number of High Motor Point, the computer 2 controls the opening of the air actuator to the value Si 'referential, it then gradually reduces to the first value Si from the performing the first combustion (here at time t5). This embodiment is here illustrated in thick dashed lines on the diagram d) and was previously explained during the description of FIG. 2. It should be noted, moreover, that the instants are given here by way of purely illustrative example. the thresholds Ni of regime and P1 of pressure in the intake distributor can indeed occur before or after one with respect to the other, or even at the same time and in this case the instants t2, t3, t4 are concurrent. At time t5 occurs a first combustion in a cylinder of the engine 1. The electric machine is then deactivated (binary state E at "0") by the computer 2 of its starter mode, and stops driving the engine 1 thermal, which then turns autonomously. If this electric machine can also operate in alternator mode, it is then controlled by the computer 2 in this mode to electrically power the various electrical consumers of the vehicle 100. Otherwise, it is completely disabled until receiving the next boot or restart command. Furthermore, between times t4 and t5: the pressure P in the intake manifold continues to decrease under the effect of the rotation of the engine 1; the ignition advance AA progressively reaches the value AA1 25 controlled at time t4, then is kept constant during this time interval by the computer 2; the duration D of injection is kept constant at a first value D1, the time that the ignition advance AA reaches the maximum value AA1: that is to say when the value of the ignition advance AA still transits between its initial null value and its maximum AA1 value. The injection time D is subsequently progressively decreased from the first value D1 to a second value D2, corresponding to the injection duration applied for the idling speed of the engine 1. This decrease in the injection duration D starts as soon as that the value of the ignition advance AA reaches its maximum value AA1 and occurs as the pressure P decreases within the intake manifold; The mass M of fuel is injected at a constant value M1, from the beginning of the injection until the occurrence of the first combustion in a cylinder of the engine 1, performed at time t5. At time t6, the speed N of the engine 1 passes up the N3 setpoint of idle speed of the engine. The time of exceeding this set point N3 corresponds to the beginning of a phase of exceeding the engine idling speed, commonly known as the "over shoot" phase. In parallel, the pressure P in the intake manifold continues to decrease, as well as the duration D of fuel injection, in connection with the evolution of the vacuum in the intake manifold. Furthermore, between times t5 and t6, the opening section S value of the air actuator is progressively controlled by the computer 2 towards a second value S2 of opening section smaller than the first value S of section d 'opening ; the pressure P in the intake manifold and the fuel injection time D continue to decrease; the mass M of injected fuel is progressively increased, as a consequence of the evolution of the preceding parameters, up to a maximum value M2. The mass M of fuel injected is subsequently gradually decreased from the maximum value M2 to a lower value M3, this lower value M3 corresponding to the mass M of fuel injected during the idling speed of the engine 1. This mass decrease M injected fuel is controlled by the computer 2, as soon as the maximum value M2 is reached. At time t7, the pressure P in the intake manifold reaches a second threshold P2 of pressure. Advantageously, this instant corresponds to the beginning of the transition of the operating parameters of the motor 1, from an open-loop control to a closed-loop progressive control (see FIG. 2 previously described). At this moment, the duration D of injection continues to decrease and the computer 2 gradually controls the opening section S of the air actuator to the third value S3 of opening section smaller than the second value S2 of opening section 35; The value of the ignition advance AA from its maximum value AA1 to a second value AA2 lower than the maximum value AA1. The control by the computer 2 of the operating parameters of the engine 1, in particular the reduction of the opening section S of the air actuator, the injection duration, the ignition timing, coupled the gradual and continuous decrease of the pressure P within the intake distributor, then causes the N regime of the thermal engine 1 to continue to increase up to a maximum value N5, commonly known as the regime of " over shoot. This maximum value N5 ("over 10 shoot" regime) is here reached at time t8. Furthermore, between the instants t7 and t8, via the application of the commands from the computer 2 - the duration D of injection reaches the second value D2, corresponding to the injection duration applied for the idle speed of the engine 1, and is kept constant; The opening section S of the air actuator reaches the third value S3, corresponding to the opening of the air actuator applied during the engine idling speed, and is kept constant; the value of the ignition advance AA reaches the second value AA2; the mass M of injected fuel converges to the value M3, which is the mass of fuel consumed during the idling speed of the engine 1. At time t9, the speed N of the engine passes a setpoint down N4. According to various embodiments, the set point N4 corresponds to the value of the idle speed setpoint N3 added to a predefined number of engine speeds (for example: 50 rpm) or multiplied by a predefined parameterizable factor (for example: 1.1). . Advantageously, the achievement of this N4 downward, corresponds to the end of the phase of "over shoot" of the engine 1. From this moment, then begins the phase of regulation of the engine idling speed and the The ignition advance AA is progressively controlled to a final set value AA3. The computer 2 can, for example, detect the beginning of the regulation phase of the engine idling speed at the instant t9, by comparison between the engine speed N and the setpoint value N4 which is previously parameterized or estimated by the computer 2. Finally, at time t10, the N engine speed is stabilized at the setpoint 35 N3, corresponding to the constant value of engine idle speed 1. The pressure P in the intake manifold has reached a stabilized value P3, the ignition advance has converged towards the final set value AA3. All the other parameters are kept constant except for the mass M of injected fuel, which gradually decreases, as the heat transfer towards the walls of the combustion chamber decreases under the effect of the temperature rise of the walls, cooling and lubricating oil of the engine 1. The starting phase of the thermal engine 1 is then completed. Advantageously, thanks to the embodiments illustrated in this figure and vis-à-vis the state of the art (in phantom), it can be seen that the pressure P in the intake distributor converges more rapidly. to the value P3 of minimum pressure due to the value Si section S opening then taken by the air actuator, less than the value Si 'referential. Indeed, an opening section S of the larger air actuator, implies a lower increase in the ignition advance AA, and therefore a later loopback of the operating parameters of the engine 1. In contrast , in the illustrated embodiments, the convergence of the ignition advance AA to a final target value AA3 is effected from above, thanks to a reduced opening of the air actuator and to a setting of Faster depression of the intake manifold, the pressure P in the intake manifold converging more rapidly to the value P3. This makes it possible to reach the closed-loop control regime of the operating parameters of the engine 1 more quickly. As a result, the mass of fuel consumed in the proposed embodiments is reduced. [0058] Advantageously, the previously described embodiments allow, during a start-up phase, to empty more rapidly the air initially contained in the intake distributor and in the combustion chamber of the cylinders. From the moment of start of the start operation, under the action of the electric machine, some pistons 30 begin their descent phase in their corresponding cylinder, the air intake valves being open. The air pressure in the intake manifold therefore decreases more rapidly, and its minimum pressure value P3 (low point) is reached between at least 0.5 and 1 second faster. The amount of fuel injected follows in parallel the same evolution. It thus becomes possible, during the start-up phase, to start reducing the quantity of fuel injected earlier, and this without degrading the speed of exceeding the engine idle setpoint ("over shoot" regime). . The closed-loop control of the injection and air flow management parameters is in fact anticipated, which makes it possible to lower the various engine speed thresholds, in particular the engine speed at which the transition to the engine speed occurs. Closed-loop regulation of injection and airflow management parameters, as well as the "over shoot" regime by reducing, during the whole start-up or restart phase, the quantities of air and of fuel allowed in the combustion chambers. The phase of exceeding the engine idle setpoint is thus also improved, via a decrease in the maximum amplitude of the engine rotational speed during this phase. The anticipation of the closed-loop regulation of the injection and air flow management parameters also makes it possible to optimize the control of the opening section S of the air actuator and of the advance with the ignition AA, which allows a further reduction of the fuel consumption. Moreover, the reduction of injected fuel is variable according to the thermal engine 1 at the time of its start or restart, and is a function of the priming state of the various bodies of post-treatment of 20 polluting emissions engine 1, such as three-way catalyst, traps nitrogen oxides, combined or not with the exhaust gas recirculation loop (EGR). Thus, for a start or a restart, the computer 2 can decide to apply the previously described embodiments, only if one or more of the following conditions are met: the temperature of the engine 1 (for example: the temperature of its liquid cooling) exceeds a preconfigured temperature set point, for example 30 to 40 ° C; the temperature of the air in the intake manifold at the inlet of the combustion chambers exceeds a preconfigured temperature setpoint; all the pollution control members are primed, for example by evaluating the temperature of the exhaust gas or the temperature in the catalyst. Advantageously, for the embodiments described above, the computer 2 differentiates the different types of start-up or restart, such as automatic start-ups via the "Stop and Start" function or the locked-up starts, and takes into account the thermal engine 5 and its altitude, to control the various parameters of injection and management of air circulation. The embodiments described above are therefore applicable to any automobile vehicle 100 equipped with an electric machine for driving its engine 1 during a start, equipped or not with the "Stop and Start" function. [0061] Advantageously, the previously described embodiments make it possible to save a fuel mass of between 0.7 and 1 g when applying an ECE-EUDC driving cycle (European driving cycle), and between 0.3. and 0.6g for the application of a WLTC driving cycle (acronym for "W orld Harmonized Light Vehicle Test Cycle"). These embodiments also make it possible to improve the acoustic and vibratory behavior of the powertrain, thanks to the control by the computer 2 of the number of top dead spots before a first combustion in a cylinder of the engine 1. [1] [0063] More generally, all of the proposed embodiments contribute to reducing the pollutant emissions of a motor vehicle.

Claims (9)

REVENDICATIONS1. Method for automatically starting a spark ignition internal combustion engine (1) for an automobile vehicle (100), the engine (1) being coupled to an electric machine capable of enabling its driving, the engine (1) being connected as input to an inlet manifold and outlet to an exhaust manifold, an air actuator being arranged upstream of the inlet manifold so as to regulate the flow of air therethrough, this method being characterized in that it comprises the steps of: upon receipt of a start command, controlling the power-up of the electric machine, so as to begin driving the motor (1); when the driving of the motor (1) begins, to impose on the air actuator a first value (Si) of opening section less than a reference value (Si '), this reference value (Si') being calculated as a function of the thermal state of the engine (1) and being particularly adapted to guarantee the success of a first combustion from the occurrence of a first combustion cycle in a cylinder of the engine (1); comparing the engine speed (N) (1) with a first speed threshold (Ni), and comparing the pressure (P) in the intake manifold with a first threshold (P1) of pressure; controlling the injection of a mass (M) of fuel into the engine (1) and controlling the ignition timing from a zero initial value to a maximum value (AA1) when the first speed threshold ( Ni) is crossed upwards by the engine speed (N) and the first pressure threshold (P1) is crossed down by the pressure (P) in the intake distributor; - To cut the electric machine following the occurrence of a first combustion in a cylinder of the engine (1); subsequently regulating the operating parameters of the engine (1) to converge towards a setpoint (N3) of idle speed, in particular able to allow the establishment of the engine idling speed (1). The method of claim 1, further comprising the steps of: counting the number of High Engine Points for each cylinder of the engine (1) and comparing that number with a predefined number; when the number of the highest motor point reached reaches the predefined number and in the absence of a first combustion, to impose on the air actuator the reference value (Si ') for opening section, so as to realize a first combustion in a cylinder of the engine (1), then to control a progressive decrease of this value (Si ') of opening section reference to the first value (Si) opening section. 10 3. The method of claim 1 or 2, wherein the mass (M) of fuel is injected during a period (D), this duration (D) being controlled so as to: be kept constant at a first value (D1) when the value of the ignition advance is controlled between its initial null value and its maximum value (AA1); being progressively decreased from the first value (D1) to a second value (D2) corresponding to the injection duration applied for the engine idle speed (1), as soon as the value of the ignition advance has reached its maximum value (AA1). 20 4. Method according to any one of claims 1 to 3, wherein the mass (M) of fuel is injected at a value (M1) constant from the start of its injection to the occurrence of a first combustion in a cylinder of motor (1). 5. Method according to any one of claims 1 to 4, wherein, between a moment of occurrence of a first combustion in a cylinder of the engine (1) and a moment of crossing up the set point (N3 ) of the engine idling speed (N) (1) the opening section value of the air actuator is progressively controlled to a second value (S2) of opening section smaller than the first value (Si) opening section; the mass (M) of injected fuel is progressively increased until reaching a maximum value (M2). 6. The method of claim 5, wherein upon reaching the maximum value (M2) mass (M) of fuel, the mass (M) of fuel 35 is controlled so as to gradually converge to a value (M3). Lower, this lower value (M3) corresponding to the mass (M) of fuel injected during the engine idling speed (1). 7. The method of claim 5 or 6, wherein when a second threshold (P2) of pressure, lower than the first threshold (P1) of pressure 5 is crossed down by the pressure (P) in the intake manifold the opening section value of the air actuator is progressively controlled to a third opening section value (S3) smaller than the second opening section value (S2); the value of the ignition advance is progressively controlled from its maximum value (AA1) to a second value (AA2) lower than the maximum value (AA1). 8. A method according to claim 7, comprising detecting a control phase of the idling speed of the engine (1) by comparing the speed (N) of the engine (1) with a reference value (N4) crossed to the low; the progressive control of the ignition advance to a final value (AA3), lower than the second value (AA2), as soon as the occurrence of the regulation phase of the engine idling speed (1) is detected. 20 9. Computer (2) equipping a vehicle (100) automobile, configured to apply a method of automatic start of an engine (1) according to any one of claims 1 to 8.