EP0932751B1 - Method for synchronising the electronic control system of an internal combustion engine - Google Patents

Description

The present invention relates to a method synchronization of the electronic system control of an internal combustion engine four-stroke type twin cylinder and injection multi-point electronic fuel.

The invention relates more precisely to a process capable of generating a synchronization signal allowing to follow the progress of the functioning (succession of different times engine) in each of the engine cylinders, this synchronization signal for identification of a predetermined instant in the course of the cycle, such as the transition to Top Dead Center Admission or even at the bottom dead center Admission.

In order to improve functioning internal combustion engines both from the point of view of performance only from the perspective of emission of pollutants, many systems fuel injection have been developed. Among these we can cite injection systems indirect electronically controlled multipoint, such as the RENIX system designed by the applicant.

One of the important features of multipoint electronic injection is its intermittent operation, the injectors are in effect activated periodically: at least once per engine cycle, or again in the case of a four-stroke engine once for two turns crankshaft or 720 ° angle.

Among the main modes of opening injectors figure sequential actuation which consists of operating the fuel injection operating successively and in a given order, the different injectors so as to inject into each cylinder at best compared to the phase corresponding admission. injection sequential is preferably phased so that that the opening of each injector ends before opening the intake valve of the corresponding cylinder, opening just starting before switching to Neutral Top Admission of corresponding cylinder.

However the systems allowing to operate a multipoint electronic injection of the type sequential phased, have the disadvantage to generate a significant additional cost compared to a conventional electronic injection system "Full Group" type where all the injectors are activated simultaneously.

Indeed, such injection systems have in particular need to have means of location very precise sequence of the engine cycle in each of the cylinders, to allow the central engine control electronics calculate and control the flow rate of each injector at a time adequate predetermined, outside the period opening of the corresponding valve.

It is customary, as disclosed in French patent application FR-A-2,441,829, to identify, on a disk (or target) secured to the crankshaft, angular position zones corresponding to a specific phase of the race different pistons. The disc has locating elements arranged along its periphery, such as length teeth different, and who passing in front of an organ fixed receiver, generate electrical pulses to produce a signal identifying the change to the top dead center position of a piston determined.

Such a tracking device turns out however insufficient for piloting a sequential phased injection. Indeed, for a four-stroke internal combustion engine, the crankshaft performs two full turns (or 720 ° angle), before a given piston ends up in the same operating position in the cycle engine. It follows that from the single observation of the rotation of the target united with the crankshaft, it is, a priori, not possible to provide information on each cylinder without an indeterminacy of two engine times in the cycle (marking the Top Dead Center position covering both the Admission phase and the Relaxation phase).

The precise determination of the position of each cylinder in the cycle, also called cylinder coding, which cannot be inferred from the only observation of the position of the crankshaft, looking for additional information is therefore necessary to know if the cylinder is in the first or in the second half of the cycle engine (intake and compression phases during first crankshaft turn, Relaxation phases then Exhaust during the second round).

In order to obtain such information complementary, we conventionally use tracking elements carried by a transmitting disc which rotates half as fast as the crankshaft. For this purpose, we can arrange this transmitting disc on the camshaft or on the ignition distributor which is driven by through a ratio reducer 1/2 to from the crankshaft.

Conventionally therefore, the camshaft (or still the camshaft drive pulley) is equipped with a target bearing a mark which cooperates with a fixed sensor to deliver a frequency signal worth "1" during the first half of the cycle and "0" during the second half. It is the combination of signals from the sensor crankshaft and camshaft sensor which allows the electronic control system to have a synchronization signal allowing, thanks to identifying a predetermined time in the cycle operating in each of the cylinders, to operate a phased sequential injection.

Such angular tracking systems using both a crankshaft sensor and a camshaft sensor are relatively bulky, expensive and delicate assembly. In in addition, in the event that one of the sensors falls into failure, i.e. in operating mode degraded engine, measurement systems classics do not provide enough information to the control system engine electronics driving the injection, hence a risk of deregulation of the latter.

The object of the present invention is to remedy the disadvantages of tracking systems known used to operate systems engine control electronics operating a phased sequential injection, by proposing a electronic system synchronization process simple and efficient control requires no specific position sensor in apart from the one used to locate the position angle of the crankshaft.

The system synchronization process combustion engine control electronics internal multi-cylinder, according to the invention, consists to produce a synchronization signal, intended especially in the phasing of the injection, which allows the identification of a predetermined instant in the course of each person's operating cycle cylinders, such as shifting to Neutral High Admission (or even the transition to Neutral Low Admission, etc.).

This synchronization signal according to the invention is deduced from two distinct signals produced by suitable processing means using in particular the information provided by a angular position sensor cooperating with a ring gear carried by the crankshaft engine. The first signal provides an estimate of the level of successive combustions occurring in the engine cylinders and the second signal follows the displacement of the pistons and in particular their passage in a predetermined position such as the Point Death High.

a) élaboration d'un signal de synchronisation phasé avec le second signal repérant le passage des pistons dans une position prédéterminée telle qu'au Point Mort Haut, ce signal de synchronisation étant initialisé arbitrairement de sorte que l'identification d'un instant prédéterminé dans le déroulement du cycle de chacun des cylindres soit opérée avec une indétermination de deux temps dans le déroulement du cycle moteur ;

b) suivi du fonctionnement du moteur et lorsque des conditions prédéterminées sont réunies ;

c) modifications des paramètres de commande du moteur concernant au moins deux cylindres donnés dont les cycles de fonctionnement sont décalés de deux temps moteur, cette modification des paramètres de commande provoquant des variations adaptées et de sens opposé du niveau des combustions dans ces cylindres ;

d) calcul pour les cylindres concernés par les modifications de l'étape c) d'une grandeur algébrique représentative des variations des niveaux de combustion, l'affectation à chacun des cylindres des valeurs correspondantes des niveaux de combustion déduites du premier signal étant opérée en exploitant ledit signal de synchronisation tel que défini à l'étape a) ;

e) déduction à partir du signe de la grandeur algébrique représentative des variations de niveaux de combustion entre les cylindres, de l'exactitude du signal de synchronisation et correction du signal si l'initialisation arbitrairement opérée à l'étape a) s'avère erronée.

According to the invention, the method for synchronizing the electronic control system is characterized in that it comprises the following steps:

a) preparation of a phased synchronization signal with the second signal identifying the passage of the pistons in a predetermined position such as at Top Dead Center, this synchronization signal being arbitrarily initialized so that the identification of a predetermined instant in the course of the cycle of each of the cylinders is operated with an indeterminacy of two times in the course of the engine cycle;

b) monitoring the operation of the engine and when predetermined conditions are met;

c) modifications to the engine control parameters relating to at least two given cylinders whose operating cycles are offset by two engine times, this modification of the control parameters causing suitable and opposite variations in the level of combustion in these cylinders;

d) calculation for the cylinders concerned by the modifications of step c) of an algebraic quantity representative of the variations in the combustion levels, the assignment to each of the cylinders of the corresponding values of the combustion levels deduced from the first signal being effected by using said synchronization signal as defined in step a);

e) deduction from the sign of the algebraic quantity representative of the variations in combustion levels between the cylinders, from the accuracy of the synchronization signal and correction of the signal if the initialization arbitrarily carried out in step a) turns out to be erroneous .

According to the invention, the method of developing a synchronization signal is based on the principle of action and reaction.

The action consists in operating adapted modifications to the parameters of engine control so as to generate opposite direction variations in the level of combustion in two cylinders whose cycles are offset by 360 ° crankshaft (or two-stroke engine).

Engine reaction to these changes command parameters results in corresponding changes in the level of combustions which are identifiable for example by falls and increases in the gas torque (or even variations of instantaneous regime or inlet pressure) depending on the engine operation.

So just match each of the cylinders concerned, the values of torque measured by exploiting a signal arbitrarily defined and inferred synchronization of the sign of the difference between the combustion levels of these cylinders if this synchronization signal arbitrarily defined is correct or not, and therefore correct it if it is wrong.

Indeed, if the action consists for example (for an in-line four-cylinder engine) to enrich the cylinder n ° 1 and to deplete the cylinder n ° 4 we must therefore observe, all things equal by elsewhere, that the new torque values of the cylinder # 1 are greater than the new values No. 4 cylinder torque. As a result, if the torque values assigned to cylinder # 1 are actually much higher than the values of torque assigned to cylinder n ° 4 is that the synchronization signal although arbitrarily initialized is properly phased. If, on the other hand, the new torque values assigned to the cylinder # 1 are less than the new values of torque allocated to cylinder n ° 4 is that the synchronization signal used is incorrectly phased, then it is simple to correct by shifting it by two engine times.

According to another characteristic of the process synchronization object of the present invention, the calculation provided for in step d) consists of counting positively combustion levels corresponding to the cylinders for which the changes to control parameters must cause increased levels of combustion and negatively the levels of combustion corresponding to the cylinders for which changes in the parameters of order must result in a decrease in combustion levels.

According to another characteristic of the process synchronization object of the present invention, the calculation provided for in step d) of the quantity representative of variations in levels of combustion for the affected cylinders is carried out taking into account a given number of cycles engine.

The distribution of the action over several motor cycles limit accordingly the amplitude of the variations in the combustion level and therefore to make the process of driver undetectable synchronization (lack of jerk in the operation of the engine). This number of cycles, which can be constant or even depend on the operating point engine, is determined so as to limit the variations in combustion levels while allowing rapid implementation of the process.

According to another characteristic of the process synchronization object of the present invention, the predetermined conditions required in step b) to modify the parameters of controls are adapted so that variations in combustion levels cannot be felt by the driver, these conditions being for example the value of the transmission ratio and / or maintaining the engine rotation speed or still inlet pressure in ranges of predetermined values.

According to another characteristic of the process synchronization object of the present invention, the predetermined conditions required in step b) to modify the parameters of combustion include stability conditions of all or part of the parameters acting on the engine combustion level, such as rpm engine rotation, or ignition advance, or the inlet pressure, or even the stable state auxiliary members driven by the engine.

According to another characteristic of the process synchronization object of the present invention, changes to control parameters provided for in step c) consist of changes in the amount of fuel injected in the affected cylinders.

Changes in the quantities of fuel injected into the cylinders, can be performed by application in the formulas of calculation of the injection times of a coefficient multiplicative corrector mapping according to engine operating conditions, said coefficient preferably between 0.7 and 0.99 for a cylinder and between 1.01 and 1.3 for the other.

According to another characteristic of the process synchronization object of the present invention, changes in fuel quantities injected into the affected cylinders are adapted to engine operating conditions and in particular the pressure of the intake air, so as to produce a variation in the level of combustion in the cylinders which is substantially identical regardless of the operating point of the motor.

According to another characteristic of the process synchronization object of the present invention, the first signal to monitor the level combustions in each cylinder operates a quantity representative of the gas torque generated by each of the engine combustions.

According to another characteristic of the process synchronization object of the present invention, the calculation provided for in step d) consists of counting the combustion levels after a period of adapted timing according to the modifications of the control parameters operated in step c).

According to another characteristic of the process synchronization object of the present invention, changes to the control parameters of the engine provided in step c) are suitable for generate at least one cyclic variation of the levels combustion in each of the affected cylinders, each cycle consisting of a first period during which the combustion level is improved for one cylinder and degraded for the other, and a second period of the same duration as the first period and during which we reverse these variations keeping essentially the same amplitudes.

calcul pour les cylindres concernés par les modifications de l'étape c) d'une grandeur algébrique représentative des variations des niveaux de combustion pour l'ensemble des deux périodes, l'affectation à chacun des cylindres des valeurs correspondantes des niveaux de combustion déduites du premier signal étant opérée en exploitant le signal de synchronisation tel que défini à l'étape a).

Step d) then consists of a:

calculation for the cylinders concerned by the modifications of step c) of an algebraic quantity representative of the variations in the combustion levels for all of the two periods, the assignment to each of the cylinders of the corresponding values of the combustion levels deduced from the the first signal being operated by exploiting the synchronization signal as defined in step a).

This reversal of the action operated on each of the two cylinders concerned allows completely overcome the combustion level means of these cylinders since no one then retains that the gap between the "high" level and the level "low" combustion. This therefore allows get rid of differences in combustion level between the cylinders, gaps which can take important values especially with the engine aging and could overhaul causes the cylinder keying strategy.

According to another characteristic of the process synchronization object of the present invention, changes to control parameters provided for in step c) are operated so similar on several groups of two cylinders (n ° 1, n ° 4; n ° 2, n ° 3) shifted by two engine times.

The higher the number of pairs of cylinders on which one operates variations of levels of combustion in the opposite direction is important and the more is able to obtain a deviation whose sign is significant quickly, which allows reduce the process execution time synchronization.

la figure 1 est une vue schématique du dispositif de contrôle moteur intégrant le procédé objet de la présente invention ;

La figure 2 présente les différents chronogrammes caractérisant le procédé objet de la présente invention.

The aims, aspects and advantages of the present invention will be better understood from the description given below of embodiments of the invention applied to a four-stroke and four-cylinder engine, these embodiments being given by way of non-limiting example, with particular reference to the accompanying drawings, in which:

Figure 1 is a schematic view of the engine control device incorporating the method of the present invention;

FIG. 2 shows the different timing diagrams characterizing the process which is the subject of the present invention.

Referring to FIG. 1, we see, presented in a simplified way, the configuration an electronic engine control system with internal combustion using the process of synchronization object of the present invention. Only the constituent parts necessary for the understanding of the invention have been detailed.

The internal combustion engine, which is marked 1, is more particularly intended for equip a motor or road vehicle. This four-cylinder in-line engine and four time is equipped with a device for injecting the multi-point fuel with control electronics through which each cylinder is supplied with fuel from an electro-injector 5 specific.

The opening of each electro-injector 5 is controlled by the electronic system of command 7 also called the injection computer. The injection computer 7 determines the quantity of fuel injected and the instant of injection into the cycle according to the operating conditions of the engine from known adapted strategies otherwise like for example the enslavement of the richness of the fuel air-fuel mixture admitted into cylinders at a set value predetermined.

The injection computer 7 comprises conventionally a microprocessor (CPU), random access memories (RAM), read only memories (ROM), as well as analog-to-digital converters (A / D), and various input and output interfaces exits.

The microprocessor integrates circuits electronics and software suitable for process signals from sensors adapted, determine the engine conditions and put implement predefined operations in order to generate control signals at destination including injectors (and ignition coils in the case of a positive-ignition engine) according to the adapted strategies selected.

The injection computer 7 is more particularly suitable for operating an injection indirect sequential phased fuel which is to trigger each injector 5 so that the fuel injection be completed before the opening of the corresponding intake valves.

Among the input signals of the microprocessor include in particular those addressed by a crankshaft sensor 22. This sensor 22, by example with variable reluctance, is fixedly mounted on the engine mount to be positioned in front of a measuring crown 12 secured to the flywheel attached to one end of the crankshaft. This crown 12 is provided at its periphery with a succession of identical teeth and hollows except for one tooth that has been removed in order to define a absolute benchmark allowing to deduce the instant from shift to Top dead center of a cylinder piston reference data, in this case the cylinder No. 1.

The sensor 22 therefore delivers a signal Dn corresponding to the scrolling of the teeth of the crown 12. This signal Dn allows, after processing by suitable calculation means, to generate a TDC signal identifying each crankshaft U-turn simultaneous passages at Top Dead Center pistons of cylinders n ° 1 and n ° 4 then alternately the simultaneous passages at the Point Dead Top of pistons of cylinders n ° 2 and n ° 3 (The cylinder n ° 1 being for example the most close to the crown 12 and so on).

Note that in the example depicted of an in-line four-cylinder engine, presenting an ignition order according to the sequence 1-3-4-2, the pistons of cylinders n ° 1 and n ° 4 (resp. n ° 2 and n ° 3) pass simultaneously to the position Top Dead Center but at different phases of the engine cycle, one entering the intake phase and the other in the Relaxation phase.

The processing of the signal Dn emitted by the sensor 22 also allows speed measurement scrolling teeth of the crown 12, and so to obtain the instantaneous rotation speed of the engine. This signal Dn is further processed by calculation methods described below to produce a signal Cg for measuring the gas torque generated by each of the combustions.

In accordance with Figure 2, the principle of method of generating the synchronization signal according to the invention will be described.

The first step of the process object of the invention consists in creating a signal NOCYL synchronization. This NOCYL signal is more particularly suitable for spotting an instant predetermined in the course of the engine cycle used for the phasing of the injection of each of the cylinders, which in the example illustrated is the transition to Neutral High Admission but which could be the transition to bottom dead center Admission, or any other time that can be used for injection phasing.

This NOCYL synchronization signal is phased with the TDC signal and it is arbitrarily initialized to 1 (or 0), at the first detection of the change to Top dead center of a cylinder reference, such as cylinder # 1, which is therefore arbitrarily considered a Top Dead Center Admission, then it is incremented (modulo four) at each shift to Top Dead Center of a cylinder in the order of succession of combustions in cylinders.

• soit le signal NOCYL est correctement initialisé, le Point Mort Haut de référence ayant servi à l'initialisation du signal NOCYL correspondant effectivement à un Point Mort Haut Admission pour le cylindre n°1 ;
• soit le signal NOCYL est mal phasé, le Point Mort Haut de référence correspondant à un Point Mort Haut Détente pour le cylindre n°1 (et donc un Point Mort Haut Admission pour le cylindre n°4).

Given the arbitrary choice made during the initialization of the NOCYL signal, two scenarios arise:

• either the NOCYL signal is correctly initialized, the reference Top Dead Center having been used for the initialization of the NOCYL signal effectively corresponding to an Admission Top Dead Center for cylinder n ° 1;
• or the NOCYL signal is poorly phased, the Reference Top Dead Center corresponding to a Top Relax Dead Center for cylinder n ° 1 (and therefore a Top Admission Dead Center for cylinder n ° 4).

The other stages of the process object of the invention will allow this indeterminacy. To do this, the engine having been launched and operating under conditions predetermined for a certain number of cycles, we voluntarily cause a modification of engine control parameters and more especially a change in the amount of fuel injected into the cylinders (and therefore the richness of the fuel mixture injected) into correcting the injection time Ti accordingly.

The modification made which consists of enrich certain cylinders and impoverish others is suitable for causing variations in level opposite direction torque between cylinders shifted in the cycle, by two engine times. he just assign the torque values to matching cylinders using the signal NOCYL predefined and summing it for deduce from the sign the value thus obtained if the NOCYL signal is well phased or not.

The required operating conditions to operate the wealth modifications as well as the amplitudes of these modifications are chosen so as to limit the impact of the implementation of the engine operation procedure and avoid any jolting phenomenon of the vehicle that may be felt by the driver, while allowing a safe and indisputable identification by analyzing torque values provided by signal Cg.

The second step of the process therefore consists to determine if the operating conditions of the engine allow wealth changes necessary for the implementation of the invention.

The required operating conditions to limit the impact on the functioning of the driving wealth variations, concern more particularly the transmission ratio, which should preferably be above a predetermined value, as well as the parameters of engine operation including pressure and the regime which must be within ranges of predetermined values. The higher the ratio transmission is long and less the impact of a wealth modification is felt, inertia of the vehicle filtering for the jerk driver engine produced by the sudden variation in wealth on the cylinders. Conversely, the higher the ratio short and less the inertia seen from the motor is important.

It is therefore preferable to operate the wealth changes outside of ratios short that constitute the first or the walk back. On the other hand, at too low speed (slow motion) any change in wealth has a significant impact on the functioning and engine noise, and so does the factor inlet pressure. This results in the development pressure-speed operating ranges, adapted to each type of engine by measurements test benches, inside which preferentially operates the implementation of the process which is the subject of the present invention.

The required operating conditions must also allow safe location and undeniable torque alterations resulting wealth changes made. It suits therefore that the alterations detected by through the gas torque signal Cg result many wealth changes generated according to the process which is the subject of the present invention and no noise affecting the measurement signal of the gas torque Cg.

To do this, it is best to wait stabilized engine operation defined by stability conditions on the parameters acting directly on the couple: the engine rotation, intake pressure, advance to ignition, and maintenance in the same state of all trained couple consumers by the engine (air conditioning, steering pump power, heated windshield, etc.).

The stability criterion retained can be defined by maintaining parameter values selected within a range of values for a given time. The forks values can then be fixed or even given by function tables of the values taken by these parameters.

The magnitude of wealth changes operated on the different cylinders, is also adjusted according to the operating conditions of the engine to limit the impact of these modifications on engine operation and avoid all vehicle jerk phenomenon which can be felt by the driver, while allowing a safe and indisputable identification through analysis of the signal Cg of the resulting torque changes.

The operating conditions necessary for the process according to the invention being combined, the third step of the process is launched.

It consists, according to the example illustrated in Figure 2, by a modification of the wealth different cylinders. The modification of the wealth is adapted to cause variations opposite direction torque for offset cylinders 360 ° crankshaft or two-stroke engine in the cycle. A cylinder is therefore enriched during that the other is impoverished.

These changes are made by application of correction coefficients multiplicative in the time calculation formula injection of each cylinder, the coefficient enrichment being of type 1 + PARTINJ and the depletion coefficient 1 - PARTINJ, with PARTINJ between 0.01 and 0.30 and calibrated in an appropriate table depending on the conditions of operation of the engine and in particular of the inlet pressure.

Preferably, the correction coefficient PARTINJ is chosen so that the alteration of the corresponding gas torque is between predetermined threshold values Smin and Smax, Smin corresponding to the minimum value below which the decrease in torque is not discernible from the noise affecting the signal Cg, this threshold Smin therefore has a predetermined function value the noise level observed and an adjustable margin, and Smax corresponding to the maximum value above which the decrease in torque causes a jerk.

More preferably, the values of correction factor are chosen to produce a comparable effect over the entire pressure range, which is obtained by choosing values of the PARTINJ coefficient according to a function of inlet pressure.

Wealth changes take place from preferably on a two-stroke cycle.

During a first period of duration given (N motor cycles) we deplete (Ti × (1-PARTINJ)) cylinders # 1 and # 2 while enriches (Ti × (1 + PARTINJ)) the phase-shifted cylinders two-stroke engine no. 4 and no. 3. Then for a second period of the same duration we operate the reverse modification to know, we enrich (Ti × (1 + PARTINJ)) cylinders n ° 1 and n ° 2 while that we deplete (Ti × (1-PARTINJ)) the cylinders phase shifted by two engine times n ° 4 and n ° 3.

The choice of the number N is predetermined. Her value results from a compromise between the speed of implementation of the synchronization process and the amplitude of the torque variations (i.e. again the amplitude of the PARTINJ coefficient).

Simultaneously with changes in wealth performed during this third step, the process object of the invention operates in a fourth step summations of the gas torque measurements provided by the signal Cg corresponding to each of cylinders. Assigning torque values supplied by signal Cg to cylinders is operated by exploiting the signal NOCYL predefined.

Summons to be representative of the algebraic variation of the torque level of each of the cylinders, take into account positively the couple corresponding to a enrichment and negatively the corresponding one to an impoverishment.

These summons are then brought together to constitute a representative algebraic quantity the torque difference between the cylinders.

It is then enough in a last step to know the sign of this last greatness representative of the torque difference between the cylinders to deduce the phasing accuracy of the NOCYL signal.

Indeed, let S1 be the sum for the first gas couple period corresponding to different cylinders. The sum S1 is operated in positively accounting for torque values corresponding to the rich cylinders and negatively the corresponding torque values to poor cylinders.

   avec Cg'j,i valeur du couple généré par la combustion dans le cylindre identifié comme étant le cylindre n°j par le signal NOCYL lors du i^ième cycle moteur suivant le début de la première période. La sommation débute avec une temporisation de n-1 cycles (au moins un cycle) afin que les mesures de couple prises en compte correspondent effectivement aux nouvelles richesses.So we have :

with Cg'j, i value of the torque generated by combustion in the cylinder identified as being cylinder n ° j by the signal NOCYL during the i ^th engine cycle following the start of the first period. The summation begins with a time delay of n-1 cycles (at least one cycle) so that the torque measurements taken into account effectively correspond to the new wealth.

Given the indeterminacy of two motor time linked to the NOCYL signal, so we have two possible cases, either the NOCYL signal is correctly phased and the value Cg'j, i corresponds actually at the torque value Cgj, i of the cylinder j, either the NOCYL signal is incorrectly phased and the value Cg'j, i corresponds to the torque value of the cylinder k two-phase phase shift from the cylinder j.

As a first approximation, we can consider that the excess or withdrawal of fuel (+/- Ti × PARTINJ) operated on the cylinders causes alterations in torque of the same value but of opposite sign between the cylinders. We then have: Cg1, i = Cg1 - ΔCg; Cg2, i = Cg2 - ΔCg; Cg3, i = Cg3 + ΔCg; Cg4, i = Cg4 + ΔCg; with Cgj mean value of the torque at the operating point considered for cylinder n ° j and ΔCg torque correction value strictly positive.

si le signal NOCYL est bien phasé

soit S1 = (N-n) × ((Cg4+Cg3-Cg1-Cg2) + ΔCg)

et si le signal NOCYL est mal phasé

soit S1 = (N-n) × ((Cg1+Cg2-Cg3-Cg4) - ΔCg)

The formula (I) therefore becomes:

if the NOCYL signal is well phased

let S1 = (Nn) × ((Cg4 + Cg3-Cg1-Cg2) + ΔCg)

and if the NOCYL signal is badly phased

let S1 = (Nn) × ((Cg1 + Cg2-Cg3-Cg4) - ΔCg)

We carry out in parallel for the second period the sum S2 of the gas couples corresponding to the different cylinders, the sum S2 being operated by positively accounting for torque values corresponding to the cylinders rich and negatively the values of couples corresponding to poor cylinders.

   avec Cg'j,i valeur du couple généré par la combustion dans le cylindre identifié comme étant le cylindre n°j par le signal NOCYL lors du i^ième cycle moteur suivant le début de la seconde période.We thus have:

with Cg'j, i value of the torque generated by combustion in the cylinder identified as being cylinder n j by the signal NOCYL during the i ^th engine cycle following the start of the second period.

This second summation begins with the same delay of n-1 cycles (at least one cycle) so that on the one hand the torque measurements recorded effectively take into account the new wealth changes and secondly so that the sums S1 and S2 have the same number (N-n) of terms.

Similarly, given the indeterminacy of two engine times linked to the NOCYL signal, so we have two possible cases, either the NOCYL signal is correctly phased and the value Cg'j, i corresponds actually at the torque value Cgj, i of the cylinder j, either the NOCYL signal is incorrectly phased and the value Cg'j, i corresponds to the torque value of the cylinder k two-phase phase shift from the cylinder j.

We can also and similarly consider that the excess or withdrawal of fuel (+/- Ti × PARTINJ) operated on the cylinders during this second period causes changes in torque of the same value but of opposite sign between the cylinders and corresponding to the alterations of the first period. We then have: Cg1, i = Cg1 + ΔCg; Cg2, i = Cg2 + ΔCg; Cg3, i = Cg3 - ΔCg; Cg4, i = Cg4 - ΔCg; with Cgj mean value of the torque at the operating point considered for cylinder n ° j.

si le signal NOCYL est bien phasé

soit S2 = (N-n) × ((Cg1+Cg2-Cg3-Cg4) + ΔCg)

et si le signal NOCYL est mal phasé

soit S2 = (N-n) × ((Cg4+Cg3-Cg1-Cg2)- ΔCg)

On opérant alors l'addition des deux sommes S1 et S2 on obtient donc la somme S totale : (III)   S = S1+ S2

si le signal NOCYL est bien phasé (III.1)   S = 2 × (N-n) × ΔCg

si le signal NOCYL est mal phasé (III.2)   S = - 2 × (N-n) × ΔCg

Formula (II) therefore becomes:

if the NOCYL signal is well phased

either S2 = (Nn) × ((Cg1 + Cg2-Cg3-Cg4) + ΔCg)

and if the NOCYL signal is badly phased

either S2 = (Nn) × ((Cg4 + Cg3-Cg1-Cg2) - ΔCg)

We then add the two sums S1 and S2 to obtain the total sum S: (III) S = S1 + S2

if the NOCYL signal is well phased (III.1) S = 2 × (Nn) × ΔCg

if the NOCYL signal is badly phased (III.2) S = - 2 × (Nn) × ΔCg

si S > 0 alors NOCYL est bien phasé,

et si S < 0 alors NOCYL est mal phasé, il est alors possible de le corriger en le déphasant de deux temps moteur.

We therefore see that the sign of the sum S provides direct information on the accuracy of the NOCYL signal:

if S> 0 then NOCYL is well phased,

and if S <0 then NOCYL is poorly phased, it is then possible to correct it by phase shifting it by two engine times.

si S > e alors NOCYL est bien phasé,

et si S < -e alors NOCYL est mal phasé.

To improve the performance of the strategy implemented, the decision criterion indicating whether the NOCYl signal, well or poorly phased, consists not in comparing S with 0 but with a threshold value e (e being a strictly positive calibrated value). So :

if S> e then NOCYL is well phased,

and if S <-e then NOCYL is poorly phased.

The introduction of e gives a margin of security to strategy. In case S is between -e and e then no decision is taken and the request is made to perform a new cylinder keying attempt.

According to the method described, the sum S is independent of the average torque values of different cylinders. It only depends on torque alteration resulting from the coefficient corrector applied 1 +/- PARTINJ and the number of engine cycles taken into account. The dispersions of torque between cylinders is therefore not involved in the implementation of the method according to the invention.

This method has many benefits. The calculation of the sum S being calculated with a large number of torque values, The influence of noise on the measurement of torque decreases, the errors compensating each other. Furthermore, the calculation based on a large number of torque values it is possible to operate with a small torque deviation ΔCg and in particular lower than the noise affecting the signal Cg, which further limits the impact of the strategy on the behavior of the engine.

Likewise, the strategy implemented frees itself from the error made on the calculation of the gas couple Cgj, i. Indeed, the rich-poor permutation partially compensates for the error made on estimating the torque, we add the error when the cylinder is rich, we subtract the error when the cylinder is poor. This strategy frees itself from instabilities on the torque which can to exist. The impact of poor combustion is diluted by the large number of torque values taken into account.

Furthermore, the symmetry between depletion and enrichment of cylinders keeps overall wealth substantially constant and therefore not to affect exhaust gas cleaning by conversion Catalytic.

Of course, the invention is by no means limited to the embodiment described and illustrated which was only given as an example.

On the contrary, the invention includes all technical equivalents of the means described as well as their combinations if these are performed following his spirit.

So it is possible to disarm the signal NOCYL by modifying the wealth of only one pair of cylinders whose cycles of are shifted by two engine times such as cylinders # 1 and # 4 (or # 2 and # 3). This variant limits the modifications made to the engine control parameters and therefore the impact on the behavior of the latter.

(III')   S = S1 +S2 avec :

si le signal NOCYL est bien phasé (III'.1)   S = (N-n) × ΔCg c'est-à-dire S°> e ;

et si le signal NOCYL est mal phasé (III'.2)   S = - (N-n) × ΔCg c'est-à-dire S°< -e.

The previous formulas then become:

(III ') S = S1 + S2 with:

if the NOCYL signal is well phased (III'.1) S = (Nn) × ΔCg that is to say S °>e;

and if the NOCYL signal is badly phased (III'.2) S = - (Nn) × ΔCg that is to say S ° <-e.

So it is possible in a second alternative to disarm the NOCYL signal without eliminating directly the average torque values in reversing wealth changes for each affected cylinders (a rich period then a poor period or vice versa), the cycle of modification no longer counts while only one period.

et (III")   S= S1

si le signal NOCYL est bien phase :

et si le signal NOCYL est mal phase :

We then have the formulas:

and (III ") S = S1

if the NOCYL signal is indeed phase:

and if the NOCYL signal is out of phase:

S = (N-n) × ΔCg si le signal NOCYL est bien phasé et S = - (N-n) × ΔCg si le signal NOCYL est mal phasé.

If we consider as a first approximation that Cg1 # Cg2 # Cg3 # Cg4 we therefore have:

S = (Nn) × ΔCg if the NOCYL signal is well phased and S = - (Nn) × ΔCg if the NOCYL signal is badly phased.

The performance of this second variant is therefore based on the similarity of the torque values medium between the cylinders. More dispersions are large between the mean torque values of cylinders and less such a strategy is performance. If on the other hand the dispersions are weak, this strategy is effective and quick to enforce.

Of course we can combine the two variants between them. Likewise, the strategy originally presented for a cycle of modifications breaking down into two periods distinct in opposite directions can extend over several successive cycles.

As technical equivalents of resources described, wealth changes can be replaced by any other action on the engine control parameters likely to cause a deterioration in the quality of the combustion that is measurable. This is so the ignition advance in the case of a spark ignition, advance withdrawal on ignition has an effect on the gas torque which is similar to a impoverishment. To do this, the device must be of the static ignition type (one ignition control by cylinder).

Similarly, we can use the object process of the present invention with a NOCYL signal of control of injectors no longer using the tracking of passages at Top Dead Center Admission different cylinders but any other time predetermined in the course of the engine cycle can constitute a benchmark such as for example the shift to Neutral Top Relaxation (or the Low Dead Point Admission, etc.).

It is therefore possible to follow up variations in combustion levels corresponding to the modification of the parameters of motor control regardless of the measurement of average gas torque, for example by simple analysis of the instantaneous engine rotation speed, or by means of air pressure analysis of admission, or by means of current analysis spark plug ionization (for engines with controlled ignition), or by means analysis of the composition of exhaust gases using a richness probe, etc.

• soit avec des composants d'électronique analogique pour lesquels les sommateurs, comparateurs et autres filtres sont réalisés à l'aide d'amplificateurs opérationnels ;
• soit avec des composants d'électronique numérique qui réaliseraient la fonction en logique câblée ;
• soit par un algorithme de traitement du signal implanté sous forme d'un module logiciel composant d'un système logiciel de contrôle moteur faisant fonctionner le microprocesseur d'un calculateur électronique.
• soit encore, par une puce spécifique (custom) dont les ressources matériel et logiciel auront été optimisées pour réaliser les fonctions objet de l'invention : puce microprogrammable ou non, encapsulée séparément ou bien tout ou partie d'un coprocesseur implanté dans un microcontrôleur ou microprocesseur etc.

As regards the implementation of the device for measuring the gas torque resulting from combustion, whatever the embodiment chosen, it can be produced in various forms:

• either with analog electronic components for which the summers, comparators and other filters are produced using operational amplifiers;
• either with digital electronic components which would perform the function in wired logic;
• or by a signal processing algorithm implemented in the form of a software module component of a motor control software system operating the microprocessor of an electronic computer.
• or again, by a specific chip (custom) whose hardware and software resources will have been optimized to carry out the functions which are the subject of the invention: microprogrammable chip or not, encapsulated separately or else all or part of a coprocessor implanted in a microcontroller or microprocessor etc.

Similarly, the invention includes all technical equivalents applied to a internal combustion whatever its type injection, the fuel used diesel or petrol or the number of its cylinders.

Claims (12)

1. Method for producing a synchronisation signal (NOCYL) for the electronic control system (7) of a multiple cylinder, four-stroke internal combustion engine (1), said synchronisation signal (NOCYL) allowing a pre-determined instant in the progress of the engine cycle to be indexed in each of the engine cylinders, such as passing to intake top dead centre, said signal NOCYL being calculated from a first signal (Cg) and a second signal (PMH) produced by suitable processing means using, in particular, the data provided by an angular position sensor (22) cooperating with a toothed crown (12) carried by the engine crankshaft, said first signal (Cg) providing an estimate of the level of successive combustions taking place in the engine cylinders, and said second signal (PMH) indexing the displacement of the pistons, and particularly the passing thereof into a pre-determined positioning the operating cycle such as the top dead centre, characterised in that it comprises the following steps:

   a) forming a synchronisation signal (NOCYL) phased with the second signal (PMEI) indexing the passing of the pistons into a pre-determined position such as the top dead centre, said synchronisation signal (NOCYL) being initialised arbitrarily such that the identification of a pre-determined instant in the progress of the cycle of each of the cylinders, such as passing to the intake top dead centre, is performed with lack of determination of two working strokes in the progress of the engine cycle;

   b) following the engine operation and when the pre-determined conditions are met;

   c) modifications to the engine control parameters (Ti) concerning at least two given cylinders (no. 1 and no. 4), the cycles of which are offset by two working strokes, said modification of the control parameters causing suitable and opposite variations in the level of combustions in said cylinders;

   d) calculating for the cylinders (no. 1, no. 4) affected by the modifications of step c) an algebraic quantity (S) representative of the variations in levels of combustion, the influencing of each of the cylinders (no. 1, no. 4) by values corresponding to combustion levels calculated from the first signal being performed by using said synchronisation signal (NOCYL) such as denned in step a);

   e) calculation from the sign of said algebraic quantity (S) representative of the variations in levels of combustion between the cylinders (no. 1, no. 4) of the precision of the synchronisation signal (NOCYL), and correction of said signal if the initialisation arbitrarily performed in step a) is proved to be incorrect.
2. Method for producing a synchronisation signal (NOCYL) according to claim 1, characterised in that the calculation provided at step d) consists of counting positively the combustion levels corresponding to the cylinders for which the modifications to the control parameters have to involve an increase in combustion levels, and negatively the levels of combustion corresponding to the cylinders for which the modifications of the control parameters have to involve a reduction in the combustion levels.
3. Method for producing a synchronisation signal (NOCYL) according to any one of claims 1 to 2, characterised in that the calculation provided at step d) of the quantity (S) representative of the variations in combustion levels is performed taking into account a given number of engine cycles (N - n; 2 x (N - n)).
4. Method for producing a synchronisation signal (NOCYL) according to any one of claims 1 to 3, characterised in that the pre-determined conditions required at step b) in order to perform modification of the control parameters are adapted so that variations in the levels of combustion cannot be felt by the driver, said conditions being, for example, the value of the transmission ratio and/or the maintenance of the engine speed, or the manifold pressure, within pre-determined ranges of values.
5. Method for producing a synchronisation signal (NOCYL) according to any one of claims 1 to 4, characterised in that the pre-determined conditions required at step b) in order to perform modification of the control parameters include conditions of stability of all or some of the parameters acting upon the engine combustion level, such as the engine speed, or the sparking advance, or the manifold pressure, or the stable state of the auxiliary members driven by the engine.
6. Method for producing a synchronisation signal (NOCYL) according to any one of claims 1 to 5, characterised in that the modifications to the control parameters provided at step c) consist of modifications to the quantities of fuel injected (Ti) into the cylinders concerned (no. 1, no. 4).
7. Method for producing a synchronisation signal (NOCYL) according to claim 6, characterised in that the modifications to the quantities of fuel injected (Ti) into the cylinders concerned (no. 1, no. 4) are adapted to the engine operating conditions and particularly to the air intake pressure, such as to produce a variation (ΔCg) in the level of combustion in the cylinders that is identical whatever the operating point of the engine.
8. Method for producing a synchronisation signal (NOCYL) according to any one of claims 1 to 7, characterised in that the first signal (Cg) allowing the level of combustions in each cylinder to be followed uses a quantity representative of the gas torque generated by each of the engine combustions.
9. Method for producing a synchronisation signal (NOCYL) according to any one of claims 1 to 8, characterised in that the calculation provided at step d) consists of counting the levels of combustion after a suitable period of delay (n - 1 cycles) following modifications to the control parameters performed at step c).
10. Method for producing a synchronisation signal (NOCYL) according to any one of claims 1 to 9, characterised in that modifications of the engine control parameters provided at step c) are adapted to generate at least one cyclical variation in the levels of combustion in the cylinders concemed (no. 1, no. 4), each cycle being composed of a first period during which the level of combustions is improved (+ ΔCg) for one cylinder (no. 4) and downgraded (-ΔCg) for the other (no. 1), and of a second period of the same length of time as said first period and during Which these variation are inverted while retaining substantially the same amplitudes (ΔCg).
11. Method for producing a synchronisation signal (NOCYL) according to claim 10, characterised in that step d) consists of:

    calculating for the cylinders (no. 1, no. 4) affected by the modifications of step c) an algebraic quantity (S) representative of the variations in levels of combustion for the whole of the two periods, the influencing of each of the cylinders (no. 1, no. 4) by values corresponding to the levels of combustion calculated from the first signal being performed by using said synchronisation signal (NOCYL) such as defined in step a).
12. Method for producing a synchronisation signal (NOCYL) according to any one of claims 1 to 11, characterised in that the modifications of the control parameters provided at step c) are performed in a similar manner on several groups of two cylinders (no. 1, no. 4; no. 2, no. 3) offset by two working strokes.

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