EP3308005A1

EP3308005A1 - Method for obtaining an air torque reserve for an internal combustion engine

Info

Publication number: EP3308005A1
Application number: EP16731237.0A
Authority: EP
Inventors: Philippe PONG; Alexis MARCHYLLIE
Original assignee: PSA Automobiles SA
Current assignee: PSA Automobiles SA
Priority date: 2015-06-10
Filing date: 2016-05-30
Publication date: 2018-04-18
Also published as: WO2016198763A1; FR3037359A1; FR3037359B1

Abstract

The invention relates to a method for obtaining an air reserve for a vehicle internal combustion engine during the phase in which the engine is returning to idling speed following the release of the vehicle accelerator pedal. The method is characterised in that it comprises the following steps: detection of the release of the vehicle accelerator pedal; detection of the occurrence of a pre-determined situation following the release of the accelerator pedal, said pre-determined situation depending on the speed (N) of the engine; and, upon detection of a predetermined situation, determination of the lost torque being applied to the engine at that moment and determination of an air reserve torque as a function of the lost torque, and implementation of engine operating variables such as to obtain the air reserve (201, 202, 203) corresponding to the determined air reserve torque.

Description

METHOD OF OBTAINING AN AIR TORQUE RESERVE FOR AN INTERNAL COMBUSTION ENGINE

The invention relates to a method for obtaining a supply of air, during a return to idling of an internal combustion engine in a motor vehicle.

[0002] An internal combustion engine, more commonly called a gasoline engine, comprises a predetermined number of cylinders, each forming a combustion chamber, capable of allowing the combustion of an air / fuel mixture. This combustion is supervised by a computer, also referred to as motor control, configured to adjust, via actuators, various engine operating parameters influencing this combustion, for example: the regulation of the quantity of fuel. air admitted into the cylinders, the mass of fuel injected, or the ignition to trigger combustion.

For a motor vehicle, the control and regulation of different engine speeds, as well as idle phases are particularly delicate. Engine idle speed control begins when a driver lifts his foot off the accelerator. The computer then controls, via actuators, various engine parameters (for example air loop, air injection and / or fuel injection, ignition angle) in order to converge the engine speed to a setpoint value. referring to a target idle speed value that is called a static setpoint. During this phase, the computer commonly uses on-board or associated calculation means, such as a "Proportional Integral Derivative" type idling controller, commonly known as the "PID regulator". Advantageously, this type of regulator is activated only for phases of idling and stabilized idling of the engine, and helps the computer to determine the values of the engine parameters to be regulated. As illustrated in FIG. 1, this PID regulates the speed, N, so that it follows its dynamic setpoint, n. The dynamic setpoint, n, is initialized at a current engine speed, Ne, determined at initialization at time t0 of the PID regulator and converges towards the static speed setpoint, nr, in the form of a filter of 1 ^st order. In stabilized idle phase, the engine then has a speed typically around 750 rpm.

[0004] The stability of a motor running at idle speed is particularly complex to ensure. In addition, the return of the engine to an idle speed can vary considerably, depending on the initial depression of the accelerator, the engine temperature, external conditions (temperatures, pressures) or the activation of different vehicle consumers (eg pumps, air conditioner compressor, power steering, alternator).

In particular, during a return to the idle speed, encounter difficulties in adapting the torque provided at the output of the engine to the couple of losses applying to it, this pair of losses including internal friction motor, external friction, and the torque taken by the various electrical or mechanical consumers of the vehicle. This typically results in a rapid fall of the engine speed below the idle setpoint value, this situation being commonly referred to as the undershoot or undershoot, illustrated in FIG. 2, by the reference U. The computer then compensates for this. distance, for example using the PID-type idle speed controller which calculates the incrementation of an integral term, so as to compensate for undershoot and re-converge to the idle setpoint. Due to this compensation, an overshoot situation, commonly referred to as over-speed or overshoot, illustrated in FIG. 2, by the reference O, of the engine speed setpoint can then be temporarily observed, for example the time that the integral term calculated by the PID regulator returns to a lower value. In the end, the engine speed eventually converges to the static idle setpoint, nr.

The undershoot situation of the engine speed is particularly problematic because it can lead to a vibratory behavior of the engine felt as unpleasant for the driver, or even a stalled situation of the engine, thus creating a security risk.

In order to overcome this drawback, many methods are known from the state of the art, in order to converge at best the engine speed with the idle setpoint. For example, the document US6895928 proposes to control the air supply of the engine during the idle phase, by opening the intake manifold air butterfly so as to exceed more than necessary an air demand for the engine, then decrement exponentially this opening. The necessary air is made to arrive more quickly in the engine, in order to compensate for a load plug on it, this load plug resulting from the various consumers of the vehicle. This prior document is limited to consider situations where the engine is already in the idle phase, and mitigate any sub-revs, via a simple air compensation.

Another known solution is to consider a reserve of air torque for the engine. Advantageously, the reserve of air torque allows the engine to have more air than necessary to achieve a requested torque. This reserve of air torque is obtained by the computer, by controlling earlier the advance (that is to say the angle value) at ignition during a motor cycle. Thus, it is possible to obtain at the next ignition, a higher torque without waiting for the air inlet into the combustion chamber returning to an ignition angle closer to the optimum angle. Advantageously, the reserve of air torque makes it possible to immediately dispose of a supply of air, compared with the expectation of air intake into the combustion chamber resulting from the opening of the throttle valve of the inlet distributor arranged upstream. of the combustion chamber.

Several reserves exist, the most important reserve being that which will be added to the air torque setpoint of the torque structure. There are currently two types of air torque reserve for idle, namely:

a static air reserve, activated in the engine idling phase, in particular according to the engaged gear ratio, the engine coolant temperature, the air temperature in the intake manifold;

a dynamic air reserve for engine idle speed, activated in situations where the engine is approaching maximum performance.

However, for these two reserves, the air supply remains too late and too weak. Too late, because these two reserves are implemented only when the engine idling is effective. The reserve of dynamic torque requires in particular to be close to the optimum ignition angle to be engaged, and refers to a simple air compensation. Such a reserve may be insufficient in relation to the losses in order to maintain the engine idling speed. The static reserve is too low, because to limit fuel consumption, it is commonly calibrated to the minimum necessary stabilized idle phase. These reserves may therefore be insufficient to compensate for torque losses during a return to idling out of cut where the throttle is closed, and keep the engine at idle speed. Undershoot situations that could potentially lead to engine stalling, such as those initially presented, may therefore occur. All the existing solutions are therefore limited.

An object is to meet all the aforementioned drawbacks.

A second object is to limit the situations of under-revs and over-revving engine for idling phases of an internal combustion engine.

A third object is to determine an air reserve for idling return phases of an internal combustion engine.

A fourth object is to improve the driving pleasure of the driver.

A fifth object is to improve the safety of the vehicle.

For this purpose, it is proposed, in a first aspect, a method for obtaining an air supply for an internal combustion engine fitted to a motor vehicle, during a phase of return to idle speed. of this engine following an accelerator pedal release of the motor vehicle, this method being characterized in that it comprises the following steps:

detection of a release of the accelerator pedal of the motor vehicle,

detection of the occurrence of a predetermined situation, following the release of the accelerator pedal, this predetermined situation being a function of the engine speed,

and when a predetermined situation is detected: the determination of the instantaneous loss torque applying to the motor and the determination of an air reserve torque as a function of this pair of losses,

the implementation of the operating parameters of the engine, so as to obtain the air reserve corresponding to the determined air reserve torque.

In a variant, the engine comprising an idle speed regulator, the predetermined situation corresponds to reaching down by the engine speed, a preconfigured threshold, for which the regulator is not yet active.

In another variant, the engine comprising an idle speed regulator, the predetermined situation corresponds to reaching down by the engine speed of a preconfigured threshold, corresponding to a maximum activation range terminal. the idle speed regulator.

In another variant, the engine comprising an idle speed regulator, the predetermined situation corresponds to the activation of the idle speed controller.

Advantageously, the air reserve torque is determined as follows:

if the predetermined situation is detected:

allocating at each instant an air reserve torque value as a function of the difference between the loss torque and an open-loop torque corresponding to the torque necessary to maintain the engine speed at a dynamic target speed value;

if the predetermined situation is not detected: by assigning a zero value to the air reserve torque.

In a variant, advantageously, the air reserve torque is determined as follows:

if the predetermined situation is detected:

by allocating, as soon as the initial value situation is detected, the loss torque until the idle speed controller is activated, then reducing the value of this reserve torque according to the difference between the loss torque and the open loop torque when the regulator is activated;

- otherwise, assigning a zero value to the air reserve torque. Advantageously, when a predetermined situation is detected calculations relating to a strategy of return to a value of static setpoint speed of engine idle begin.

[0023] Advantageously, the calculations include:

the determination of the time gradient of the engine speed of the engine,

the comparison of this time gradient with a predetermined theoretical gradient,

- The activation of the idle speed regulator if the predetermined theoretical gradient is less than the time gradient of engine engine speed.

Advantageously, the method comprises a step of determining a factor to reduce the air torque reserve value to a zero value, during driving idling situations of the motor vehicle.

Advantageously, this method further comprises a step of filtering the air reserve torque via a low-pass filter.

Advantageously, the idle speed regulator is a Proportional Integral Derivative derived type regulator.

It is proposed, according to a second aspect, a computer fitted to a motor vehicle, configured to apply a method of obtaining an air reserve for an internal combustion engine, during a return to idle of this This method is 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:

Figure 1 illustrates an idle speed regulation according to the prior art.

- Figure 2 illustrates a regulation of idle speed according to the prior art, with the presence of under revolutions and over-revving idle.

FIG. 3 illustrates by a logic diagram the construction of the reserve torque according to the invention. FIG. 4 illustrates a motor vehicle comprising a motor and a computer programmed to regulate operating parameters of this motor according to various embodiments; FIG. 5 illustrates the evolution of the engine speed, its setpoint value, as well as the activation ranges of an air reserve according to various embodiments.

[0029] Figure 5 illustrates a vehicle 100 automobile equipped with a spark ignition internal combustion engine 1 (name referring to combustion), more commonly called gasoline engine 1.

The internal combustion engine 1 is controlled by a computer 2 (also called engine control), the computer 2 being programmed to best meet the will of the driver, retransmitted including via an accelerator pedal. Thus, the computer 2 receives various information, including those from a sensor positioned on the accelerator pedal, this information allowing it to control in particular the operating speed of the engine 1.

The internal combustion engine 1 comprises a predetermined number of cylinders each forming a combustion chamber, to allow the combustion of an air / fuel mixture controlled according to a predefined cycle, for example following a four-stroke cycle. The combustion in each cylinder is triggered by an ignition device, such as a candle disposed in an upper portion of the cylinder, this device for producing the spark necessary for the combustion of the air / fuel mixture.

The work produced by the internal combustion engine 1 comes from the combustion, initiated by the ignition device of the air / fuel mixture compressed within each cylinder by an alternately moving piston, between an extreme high position. and an extreme low position, relative to the cylinder, respectively called High Dead Point (TDC) position and Low Dead Position (TDC) position. The reciprocating movement of the piston enables the rotation of a crankshaft by means of a connecting rod connecting the piston to the crankshaft, the movement of the crankshaft being then transmitted to the wheels of the vehicle 100 via various 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 passage of the piston to the top dead center (TDC) position, the top dead center position (TDC) of the piston corresponding to the reference position. Advantageously, this ignition advance value is controlled by the computer 2.

According to various embodiments, the fuel is injected directly into the combustion chamber (direct injection), or otherwise upstream of the combustion chamber (indirect injection), the injection being performed by injectors and driven by the calculator 2.

Each cylinder is connected to an intake distributor, allowing the transport of air or air / fuel mixture to the different combustion chambers, and output to an exhaust manifold for exhaust gas of combustion. The air regulation through the inlet distributor is provided via an air regulating valve, for example a motorized throttle, whose opening section is controlled by the computer 2.

Advantageously, the computer 2 is connected by transmission lines to different sensors that provide real-time data on the automobile vehicle 100, and in particular on the engine 1. Among these data, we find in particular:

the speed N of the engine: 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 engine coolant (for example a water / antifreeze mixture), the temperature of the lubricating oil at the cylinder, or the temperature of the material of a sensitive constituent of the engine 1 (for example a zone 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 air pressure in this element, the latter being measured by a sensor placed in the intake manifold.

Advantageously, thanks to the feedback of 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: the mass of fuel injected, the duration of the injection; 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 motorized throttle upstream of the intake distributor, thus allowing the regulation of the air pressure in this member.

The computer 2 comprises various calculation means, including servocontrol means, for controlling the speed N of the engine 1 to a dynamic reference speed n value. To achieve this servocontrol, the computer 2 is associated with an idle speed controller, in charge of calculating the evolution of the values of different operating parameters of the engine 1, the application of these values making it possible to converge the speed N of the engine 1 to the dynamic set point n value. Typically the idle speed controller is disabled during the acceleration phases, and reactivated during the idling phases.

Following the determination by the idle speed controller of the operating parameter values of the engine 1, the computer 2 then applies the determined values to the engine 1 via actuators. For example, the computer 2 controls via actuators, the values of the opening section of the air regulating valve, the injection (duration, fuel mass) or in advance. ignition, so as to ensure the follow-up by the N speed of the engine 1 of the dynamic reference value n. In one embodiment, the idle speed regulator is of the "Proportional Integral Derivative" type, and hereinafter referred to as the "PID regulator".

Advantageously, the setpoint n speed value is controlled by the computer 2 to a nominal value nr of static engine idling speed (function of the gear ratio engaged), value to which it is desired to converge the speed N of the motor, which corresponds to a static setpoint.

According to various embodiments, the dynamic reference speed n value, is

either a static value (constant), its value is then fixed by the computer 2 to the value of steady state speed nr (function of the gear ratio engaged);

either a dynamic value (variable), which is for example determined by the computer 2 according to the engine speed N

1, and / or its time gradient dN / dt (variation of the speed N as a function of a time t), so as to change the speed N of the motor 1 smoothly towards the final setpoint for the stabilized idle speed.

The calculation of the static or dynamic value of the setpoint is, by way of example, carried out according to a method of the state of the art.

By way of example, in FIG. 5, the evolution (in ordinate) of the speed N of the motor and the value of regime n of dynamic reference, as a function of time t (in the abscissa), is observed. In this figure, the value of the nominal speed n is initially at the value of steady state speed nr, corresponding to the gearbox current ratio engaged. It is further assumed that at a time t0, the driver of the vehicle 100 lifts his foot off the accelerator pedal, causing a decrease in engine speed N, and then a return to the idle speed (report function gear engaged). Before the return to this idle speed, and therefore at time tO the idle speed controller (ex: PID regulator) is disabled.

At a time t1, corresponding here to the activation of the idle speed regulator, the value of the dynamic reference speed n is controlled by the computer 2 at the current value of the engine speed N, and then driven so as to decrease (eg exponential via a time constant as a function of the motor gradient) to the value of steady state nr.

From this same time t1, the speed N of the engine 1 is regulated according to various parameters whose values are determined by the idle speed controller and controlled by the computer 2. More precisely the operating parameters of the engine 1 (butterfly valve, injection, ignition advance) are controlled by the computer 2 (via actuator) following activation of the idle speed controller.

The regulation of these different parameters allows the N speed of the motor 1 to converge thereafter to the steady state nominal value nr (referring to the value of regime n setpoint). When this value is reached by the speed N and then kept constant, the engine 1 is then in stabilized idle phase, its N speed continuing during this phase to be regulated according to the values determined by the idle speed controller.

In the illustrated example, the speed curves N of the engine 1 and the dynamic reference speed n value are confused from the moment t1: the N speed of the engine 1 converges here instantly with the value of the speed n setpoint, which is brought gradually to the final value of regime nr static setpoint.

In another example, the engine speed N may, after the instant t1, differ from the setpoint n speed value, and then converge later to the static target speed nr value. The speed curves N of the engine 1 and the value of the dynamic setpoint n are therefore not always necessarily confused after the instant t3.

Different control strategies of the engine 1 can be implemented independently. These different engine control strategies are now described. Advantageously, these strategies allow

to ensure the return of the N speed of the engine 1 to the idle speed reference value nr of idling speed (function of the gear ratio engaged);

- To anticipate a possible lack of air in the engine during the N speed return of the engine 1 to the static setpoint nr value, especially when a significant loss pair is taken from the engine 1 (for example via electrical consumers in the vehicle 100).

These different strategies start, in advance, by the detection by the computer 2 of a condition on the accelerator pedal, namely a release (lifting of the driver's foot) of the accelerator pedal, consecutive to a phase of acceleration (pedal depressed). Following this lifting of the foot, the N speed of the engine 1 then decreases.

According to various embodiments, following the foot lift detection, the computer 2 is configured to detect, according to the speed N of the engine 1, the occurrence of a predetermined situation depending on the engine speed. Depending on the chosen control strategy, the predetermined situation may be:

reaching downwards by the N speed of the engine 1, in other words a downward overshoot, of a preconfigured threshold Ns, for which calculations relating to a strategy of return to the value of the static setpoint nr start. These calculations are performed by the computer 2, begin before the activation of the idle speed controller (but after the detection of a release of the accelerator pedal), then continue in the background following the activation of the latter . These calculations therefore do not contribute directly to regulate the N speed of the engine to the value of nr static setpoint, this operation being performed during the activation of the idle speed controller, but can however determine information that will allow thereafter to contribute to this regulation. By way of example, these idle return strategy calculations determine:

the time gradient dN / dt (variation of the speed N as a function of a time t) of the speed N of the engine 1, that is to say the deceleration rate of the speed N of the engine 1; the comparison of this time gradient dN / dt with a predetermined theoretical gradient derived for example from a cartography;

o a couple of instant losses. This pair of losses is, by way of example, determined by calculation or via a cartography, as a function of the following parameters: speed of the vehicle 100, speed N of the engine 1, friction losses in the engine 1 (for example depending on its temperature, of the viscosity of its lubricating oil), losses induced by the various electrical consumers of the vehicle 100 or mechanical (for example oil pump, compressor of the air conditioning);

a motor torque value, hereinafter referred to as open-loop torque or iso-power torque. This open loop torque corresponds to the theoretical necessary torque to maintain the speed on its dynamic setpoint n. It is applied when the PID controller is enabled and allows the PID controller to work only around the ON. m: idle torque = PID controller torque + open loop torque

It is here calculated as a function of the static setpoint speed value nr, the instantaneous speed N of the engine 1, and the loss pair at the same time as follows:

CBO = K x J x πΙ 30 x {nr - N) + Cpertes

With:

C _B o: open-loop couple

K: factor that can change the desired profile back to idle

J: vehicle inertia

nr: static instruction

N: engine speed

Cperies: couple of losses

When the instantaneous speed N of the motor 1 has reached its static set point, the open-loop torque is worth the loss pair. At idle, theoretically, the engine must only provide the loss torque to maintain its regime N at its static setpoint nr.

The concept of open loop means, here, that the value of idle torque is obtained via the application of a preconfigured mathematical formula on these inputs, the output obtained (idle torque) not looping back with these inputs, as opposed to a closed loop situation which can for example occur in stabilized idle phase of the engine 1; o an activation decision t1 of the idle speed controller (eg of the PID type) as a function of the time gradient dN / dt and the engine N speed 1: the idle speed controller is activated if the time gradient dN / dt is less than the gradient theoretical time. this instant of activation t1 of the idle speed regulator being later than the moment of exceeding the threshold Ns preconfigured;

reaching downwards by the N speed of the motor 1 of a preconfigured threshold Nmax, corresponding to a maximum limit of the activation range of the idle speed regulator, the minimum limit of this activation range corresponding to a preconfigured threshold Nmin . Below this threshold, the activation of the PID regulator is forced;

activation from time t3 of the idle speed controller, here to reach down by the speed N of the engine 1 of the value Ne. From this moment 1, the idle speed regulator determines the values of the various operating parameters of the engine 1 (ignition advance, injection, opening of the motorized throttle) to be regulated, so as to converge the speed N towards the value steady state nr.

When the predetermined situation is detected, the computer 2 activates a reserve of air, in order to anticipate any risk of lack of air, and therefore any risk of engine N falling down which can lead to a situation of under -regime, even calibration.

The activation of this air reserve for the three situations described above is respectively represented by the double arrows 201, 202, 203. It is observed here that this reserve of air remains activated until obtaining a stabilized idling speed of the engine 1 to the value of steady state nr.

Advantageously, the air reserve is obtained by calculating an air reserve torque. If the air reserve is not activated, that is to say when the predetermined situation is not detected, the reserve air torque associated with this air reserve is maintained at a value of zero (at 0). Nm) by the calculator 2.

According to various embodiments, following the occurrence of a predetermined situation which, according to the control strategy chosen may be one of the three situations described above, the computer 2 may determine the air reserve torque in it. assigning successively for value, the difference at each moment between the loss pair and the open-loop torque;

If the control strategy chosen is that of the detection of Nmax or that of the detection of Ns, the computer 2 can also determine the reserve air torque by attributing to it, for initial value, the value of the instantaneous loss couple as that the regulator is activated, then gradually decreasing the value of this air reserve torque as a function of the difference at each instant between the loss torque and the open loop torque when the idle speed controller is activated.

Advantageously, the air reserve torque is translated into air mass by the computer 2, via an adjustment of the operating parameters of the engine 1. For example, the computer 2 regulates the opening of the motorized throttle and / or the value of the ignition advance, according to values making it possible to obtain the air reserve torque and therefore the corresponding air reserve. The reserve air torque is therefore added to the idle torque determined by the computer 2.

As illustrated in FIG. 3, the air reserve torque 33 is, by way of example, determined from a two-dimensional cartography 30, by correspondence between a loss torque value, and a difference between the value loss torque 31 and a value 32 of idle torque in open loop. Advantageously, such mapping makes it possible to target different situations:

for low torque losses, this mapping matches a zero value to the air reserve torque. Indeed, only pairs of losses judged to be sufficiently high require a non-zero value of air reserve torque, in order to anticipate any risk of a fall in speed N (linked to the torque setpoint that can not be achieved due to lack of air );

when the engine speed N reaches the static setpoint speed value and once in the stabilized idle speed phase, the engine torque compensates the internal and external losses to the engine 1. Thus, the engine torque 1 relating to this regime is then equal to the open-loop torque plus the torque of the PID regulator and this value should be close to the loss torque, as well as the open-loop torque. It is therefore no longer necessary to have the air reserve torque. This translates in the mapping, by a zero value of the air reserve torque, when the difference between the loss torque and the open-loop idling torque is zero.

When the vehicle is idling driven, that is to say, moves without acceleration setpoint to an idle value depending on the engaged gear ratio, the inertia of the vehicle drives the engine. This has the effect of dropping the speed N of the engine 1 slowly, and the use of the reserve torque of air is not necessary. Thus, in one embodiment, the computer 2 determines a factor making it possible to reduce the air torque reserve value to a zero value during the situations of idling caused, thus making it possible to exclude these situations. This factor is by way of example determined from a map, making it possible to achieve the correspondence between different predetermined factor values and different gearbox ratios.

Moreover, as has been seen, the air torque reserve is in particular a function of the loss torque. Typically, this pair of losses is very fluctuating and therefore has a "noise" which therefore affects the determination of the air torque reserve. In order to obtain a filtered value of the air torque reserve, the strategy for calculating the reserve then applies, in one embodiment, a low-pass filter once this value has been determined.

Advantageously, the previously described embodiments make it possible to propose an air reserve during a return to idling, whereas the state of the art is limited to considering a reserve of air for idling phases. stabilized motor 1. More precisely, the state of the art proposes mainly to compensate for a lack of air compensation, when it is proven, via the use of static and dynamic reserves. By contrast, all of the proposed embodiments can anticipate a lack of air during a return to idle, while the torque is taken from the engine 1, via the sending by the computer 2 of instructions to different actuators (eg actuators control the butterfly valve, injectors).

Furthermore, all of the previously described embodiments allow the engine speed 1 to approach the best dynamic reference value during idling return phases. This therefore makes it possible to limit the situations of under-regime ("Undershoot") engine, and therefore potential stall situations. The safety of the vehicle 100 is thus reinforced.

In addition, overshoot situations resulting from temporary compensation by the idle controller of an under-regime situation are also limited. The described embodiments thus contribute not only to improving the fuel consumption in the automobile vehicle 100, but also to improving the driving comfort of the driver by limiting the vibration behavior observed during possible engine sub-revs and over-revs 1.

Claims

1. Method of obtaining an air reserve for an internal combustion engine (1) equipping an automobile vehicle (100) during a return phase to idling of this engine (1) following a accelerator pedal release of the automobile vehicle (100), characterized in that it comprises the following steps:

detecting a release of the accelerator pedal of the automobile vehicle (100),

detecting the occurrence of a predetermined situation, following the release of the accelerator pedal, this predetermined situation being a function of the speed (N) of the engine (1),

and when a predetermined situation is detected:

determining the instantaneous loss torque applying to the motor (1) and determining an air reserve torque as a function of this loss pair,

implementing the operating parameters of the engine (1), so as to obtain the air reserve (201, 202, 203) corresponding to the determined air reserve torque.

2. Method according to claim 1, the engine comprising an idle speed regulator, wherein the predetermined situation corresponds to reaching down by the engine speed (N) (1), a threshold (Ns). preconfigured, for which the controller is not yet active

3. Method according to claim 1, the engine comprising an idle speed regulator, wherein the predetermined situation corresponds to the reaching down by the engine speed (N) (1) of a threshold (Nmax) preconfigured , corresponding to a maximum limit of activation range of the idle speed controller.

The method of claim 1, the engine comprising an idle speed regulator, wherein the predetermined situation corresponds to activation of the idle speed controller.

5. Method according to any one of claims 2 to 4, wherein the air reserve torque is determined as follows:

if the predetermined situation is detected:

o allocating at each instant an air reserve torque value as a function of the difference between the loss torque and an open-loop torque corresponding to the torque necessary to maintain the engine speed at a dynamic target speed value;

- if the predetermined situation is not detected:

o assigning a zero value to the air reserve torque.

The method of claim 2 or claim 3, wherein the air reserve torque is determined as follows: if the predetermined situation is detected:

o by assigning, as soon as the initial value situation is detected to the air reserve torque, the loss momentum until the idle speed controller is activated, then reducing the value of this reserve air torque according to the difference between the loss pair and the open loop torque when the regulator is activated; otherwise, assigning a zero value to the air reserve torque.

7. Method according to any one of claims 2 to 6, wherein when a predetermined situation is detected calculations relating to a return strategy to a value of steady state (nr) engine idling start.

8. Method according to the preceding claim, wherein the calculations comprise:

the determination of the time gradient of the engine speed (N) of the engine (1),

the comparison of this time gradient with a predetermined theoretical gradient,

- The activation of the idle speed regulator if the predetermined theoretical gradient is less than the time gradient of the engine speed (N) of the engine (1).

9. A method according to any one of claims 1 to 8, comprising a step of determining a factor for returning the air torque reserve value to a zero value, in the event of idling situations caused by the vehicle (100) automobile.

10. Method according to any one of claims 2 to 9, wherein the idle speed regulator is a Proportional Integral Derivative type regulator.

11. Calculator (2) equipping a vehicle (100) automobile, configured to apply a method for obtaining an air reserve for an engine (1) internal combustion, when idling this engine ( 1) according to any one of claims 1 to 10.