CN110582627B

CN110582627B - Method for modifying the dynamics of the adjustment of the abundance value in an engine to a set value

Info

Publication number: CN110582627B
Application number: CN201880029701.4A
Authority: CN
Inventors: 西里尔·塔维罗德; 弗雷德里克·丹布里卡特
Original assignee: PSA Automobiles SA
Current assignee: PSA Automobiles SA
Priority date: 2017-05-03
Filing date: 2018-04-24
Publication date: 2022-07-22
Anticipated expiration: 2038-04-24
Also published as: FR3065990B1; CN110582627A; EP3619414A2; FR3065990A1; WO2018202977A3; MA50600A; WO2018202977A2

Abstract

The invention relates to a method for modifying the dynamics of the adjustment of the abundance to a setpoint abundance value of a measured abundance of an air/fuel mixture in a heat engine when at least one predetermined operating condition (cond1 to condx) of the engine is active. The nominal adjusted dynamics of abundance (Dyn nom) is replaced by a modified dynamics (Dyn fin) specific to the at least one condition (cond1 to condx). When the engine is pre-tested, the condition (cond1 to condx) is selected by calibrating at least one value of at least one operating parameter of the engine, the at least one value representing that the condition (cond1 to condx) is valid, and once the value is detected at a given moment of engine operation, the nominal dynamics (Dyn nom) is corrected according to the weighting term (Fpond) to give a modified dynamics (Dyn fin) when the value is detected.

Description

Method for modifying the dynamics of the adjustment of the abundance value in an engine to a set value

Technical Field

The invention relates to a method for modifying an abundance adjustment dynamics for a turbocharged engine for adjusting a measured abundance of an air/fuel mixture in the engine to an abundance set value, for example upstream of a catalyst present in an exhaust line, the upstream being selected according to a flow direction of exhaust gases in the line.

Preferably, the invention is applicable to engines with gasoline fuel controlled ignition and supercharging. The gasoline designation includes blends based on gasoline, ethanol or liquefied petroleum gas. This is not limiting and the invention can be applied to any motorized device.

Background

With reference to fig. 1, which does not limit the invention, a turbocharged heat engine 1 is shown, as well as a turbine 2 at the engine outlet. On the exhaust pipe discharging the gas from the engine 1, there is a catalyst 3, which catalyst 3 is surrounded by an upstream probe 4a and a downstream probe 4 b. Advantageously, the catalyst 3 is a redox catalyst. Such assemblies are known in the art. The exhaust line may contain one or more other selective pollution abatement elements, such as a particulate filter, an active or passive nitrogen oxide trap, or a selective catalytic reduction system for a diesel engine.

The operation of the engine is controlled by a command control unit which transmits a fuel abundance set value in the engine to the inlet of each cylinder. Method for modifying the abundance setting of a probe when scavenging is carried out in an engine by fresh air, where unburned air enters the line, the probe being the mentioned upstream probe placed in the exhaust line at the outlet of the heat engine.

Thus, the adjustment of the abundance of the air/fuel mixture in the engine may be performed according to an estimated abundance set point at an upstream probe based on a predetermined abundance set point at the engine and the measured abundance of the upstream sensor.

Advantageously, the proportional upstream probe is used to measure the abundance upstream of the catalytic converter and to adjust it around a set value determined by a command control unit of the heat engine. In most cases, when the abundance set value at the transmitter changes, more specifically the abundance set value at least one cylinder of the engine as determined by the command control unit, the probe set value is derived using a model representing the system performance and the probe performance.

The main difficulty in determining the abundance setting at the detectors is that there is typically a delay time, and variable reaction time, that can vary between the abundance setting at the engine and the abundance setting at the detectors depending on engine operating conditions, such as exhaust gas flow. To compensate for the delay time and reaction time, internal models are most often used to represent the transit time of the gas from the engine to the probe and the reaction time of the probe. Such a model is used to convert the abundance setpoint at the ejector to the abundance setpoint at the detector. This will be described in more detail below

In the following, scavenging in the engine will be taken as an example of the operating conditions. This is not limiting and the operating condition that causes the modification of dynamics may not be scavenging.

Referring again to fig. 1, in order to restart the turbocharger more quickly, with the turbine labelled 2, the commanded control unit of the engine allows scavenging to take place in certain phases. This is intended to allow fresh air to enter the exhaust pipe without being combusted by the opening overlap of the cylinder valves of the heat engine. During these phases, the average abundance upstream of the catalyst must be favorable for reducing polluting emissions.

The adjustment of the abundance upstream of the catalyst will use the abundance measurement given by the upstream probe. Based on the cylinder combustion chamber abundance setpoint or the engine abundance setpoint, the abundance setpoint at the detector can be modeled by a linear function with a delay.

To optimize the pollutant conversion efficiency of the catalyst, an abundance set point change at the upstream probe, referred to as a catalyst window, that gives a set point range around the estimated abundance set point at the upstream probe, may be defined in the abundance adjustment.

There are three major problems with adjusting the abundance setpoint at the upstream detector. A first problem is that during the scavenging activation phase, the oxygen delivered to each exhaust valve of the cylinder may change the catalyst performance for the same rich setting upstream of the catalyst. If the catalyst window is moved, optimization of the pollutant conversion will no longer be ensured.

A second difficulty is that the degree of scavenging can also affect the measured abundance of the sensor upstream of the catalyst. Indeed, experiments conducted on the engine bench have shown that for most of the scavenging rates, the higher the scavenging rate, the greater the difference between the abundance measurements given by the upstream probe and those given by the analysis device during the on-bench experiments. A third difficulty relates to the correction dynamics of the abundance setpoint as previously described.

A third difficulty, and not the smallest one among these, is that in the case of an engine in which predetermined operating conditions are valid, when an adjustment of the set value of the abundance of air/fuel mixture in the heat engine is required, an adjustment dynamic of the set value of the specific abundance is obtained that is suitable for the operating conditions.

In fact, the higher the correction dynamics, the more corrections to the estimated abundance deviations corrected by the adjustment means, advantageously the regulator, and vice versa, can be accompanied by the risk of exceeding the abundance adjustment set value. It may therefore be desirable to adjust the correction dynamics in dependence on the operating point of the engine, in particular in dependence on the rotational speed of the engine and the filling rate of one or more cylinders.

In fact, certain operating phases of the engine, for example when carrying out diagnostics, scavenging as described above, or various tests, require specific performances of the regulation device, in order to avoid in particular that the defects to be diagnosed are eliminated or that disturbances are introduced when correcting.

Document FR- A-3026780 discloses A heat engine for A motor vehicle comprising at least one cylinder, an exhaust line, an abundance detector arranged on the exhaust line, and an abundance set value determination module which determines an abundance set value at the detector from an abundance set value in the at least one cylinder. The determination module is configured to determine an abundance setting at the detector by using a first calculation rule.

The adjustment module is configured to determine an abundance correction to be implemented in the at least one cylinder based on a first calculation rule according to a value representing the difference between the abundance measured by the probe and an abundance set-point at the probe, however, this document does not relate to modifying the dynamics of the adjustment module under certain operating conditions of the engine and gives no guidance on the subject.

Disclosure of Invention

The problem underlying the invention is therefore to adjust the set value of the abundance of the air/fuel mixture in the heat engine when one or more specific operating conditions of the engine require a specific abundance adjustment dynamic different from the nominal dynamic used by default.

In order to achieve this object, according to the invention a method is provided for modifying the regulation dynamics when at least one predetermined operating condition of the engine is active, the adjustment dynamics are used to adjust the measured abundance of the air/fuel mixture in the heat engine to an abundance setpoint, characterized in that the nominal adjustment dynamics of the abundance are replaced by modified adjustment dynamics specific to at least one condition, when the engine is pre-tested in relation to the adjustment of the predetermined abundance setting at the engine, the at least one condition is selected by calibrating at least one value of at least one operating condition of the engine, the at least one value is indicative of the at least one condition being active and, upon detection of the at least one value at a given time of engine operation, the nominal dynamics is corrected in accordance with the weighting term to give a modified dynamics upon detection of the at least one value.

Certain operating phases of the heat engine require specific adjustments of the abundance correction dynamics according to the abundance setpoint value in order to prevent disappearance of the defect to be diagnosed or amplification of the introduced disturbances. This is achieved by the invention which modifies the corrective dynamics of one or more operating phases of the heat engine, which phases are identified beforehand during engine development as requiring specific dynamics.

Advantageously, the at least one condition is selected from the following parameters, alone or in combination: a scavenging rate, which is performed in the engine with fresh air and allows unburned air to enter the exhaust line at the engine outlet; a temperature of engine coolant representative of an engine temperature; performing at least one diagnosis of the engine or exhaust line; the engine is tested or adjustments to a model relating to the presence of a decontaminating element or measuring sensor in the exhaust line are tested.

Operating conditions that require modification of the abundance correction dynamics become more and more, and new conditions to be considered for modifying the abundance correction dynamics are likely to occur in the future.

Advantageously, in carrying out the test, a series of weighted terms are determined for a set of similar tests, each of the weighted terms being associated with one of the tests and being used to correct the nominal dynamics during that test.

Advantageously, at least two predetermined operating conditions of the engine are simultaneously active when the predetermined operating conditions are each associated with a respective weighted term, the weighted term selected from the two weighted terms being the lesser of the two weighted terms.

For each condition that requires a particular dynamic, a calibratable weighting term may be used. The specific values of each of the conditions are compared and a minimum value may be applied to the nominal dynamics depending on the operating point, advantageously the nominal dynamics multiplied by the minimum value, in order to obtain a modified dynamics of the abundance correction implemented by the abundance regulator.

Advantageously, the measuring sensor is a so-called upstream probe, which is arranged in the exhaust line at the outlet of the heat engine.

Advantageously, the adjustment of the abundance is made by comparing an estimated abundance set point at an upstream probe based on a predetermined abundance set point at the engine with the measured abundance at the upstream probe, and one or more parameters of the engine are adjusted such that the measured abundance value follows the estimated abundance set point at the upstream probe.

Advantageously, the set value of the abundance at the upstream probe is modelled according to a predetermined set value of the abundance at the engine, taking into account the delay time of the upstream probe, which depends on the distance between the engine and the upstream probe, and on the velocity of the exhaust gas at the current engine outlet, and in particular the reaction time for an upstream probe with an abundance of 0.63.

Advantageously, the weighting terms are obtained by means of an x-dimensional map, x being equal to 1 for a single predetermined operating condition, or x being equal to the total number of predetermined operating conditions.

Advantageously, the weighting term is a multiplication factor applied to the nominal dynamics.

The invention also relates to a drive train comprising a heat engine and a command and control unit responsible for controlling the operation of the heat engine, the command and control unit having a regulating device for regulating a regulation state for regulating a measured abundance of an air/fuel mixture in the heat engine to an abundance set value, characterized in that the command and control unit comprises means for implementing such a modification method, the command and control unit comprising: calibration means for calibrating at least one value of at least one operating parameter of the engine, the at least one operating parameter being representative of at least one predetermined operating condition of the engine, the at least one predetermined operating condition, when active, requiring a correction to the adjustment dynamics of the abundance set-point; computing means for computing a weighted term that is applied to the current dynamics to give a modified dynamics; and tracking means for tracking the at least one parameter to effect a correction when at least one value of the at least one parameter is valid.

The control rule designed by the invention is realized in the abundance regulating function, and no additional hardware is needed. The computing means determines the weighting term in dependence on one or more operating phases of the engine which require specific processing of the dynamics of the abundance regulator used to correct the abundance.

In the case where the probe upstream of the catalyst is responsible for measuring the abundance for comparison with the abundance set at this upstream probe, deduced from the engine abundance set, the invention is directly applicable to the exhaust line used, the software solution of the invention being added to the control rules already present in the command control unit. The invention allows to optimize the performance of the engine, in particular to meet the requirements in terms of pollution abatement and comfort.

The solution proposed by the invention is purely software and can be easily installed in the command control unit of the engine and, more particularly, in the function of the regulation of the abundance upstream of the catalyst, implemented by means of an upstream probe.

Drawings

Other characteristics, objects and advantages of the invention will appear upon reading the following detailed description, with reference to the attached drawings, given as a non-limiting example, in which:

figure 1 is a schematic view of an assembly of a heat engine and an exhaust line comprising a catalyst and at least one probe upstream of the catalyst, which can be used to adjust the abundance in the engine according to an abundance set value, for which a modification method according to the invention can be implemented;

figure 2 shows a logic diagram for implementing the modification method according to the invention;

fig. 3 shows an estimate of the abundance deviation between the measured abundance and the abundance setpoint based on the scavenging rate and the engine speed, which estimate is taken into account in the modified method according to the invention.

Fig. 4 shows an abundance set value curve at the engine, an abundance set value curve at an upstream probe in the exhaust line at the engine outlet, an estimation curve of the abundance set value at the upstream probe, which is performed based on the abundance set value at the engine by taking into account the delay time and reaction time of the probe, which is implemented in an embodiment of the modified method according to the invention.

Detailed Description

It should be noted that the drawings are given by way of example and not limitation. The drawings form a schematic to facilitate understanding of the invention and are not necessarily to scale for practical applications. In particular, the dimensions of the various elements shown in FIG. 1 are not intended to be actual.

With reference to all the figures, the invention relates to a method for modifying the adaptation dynamics of the abundance correction, i.e. to control the air/fuel mixture in the heat engine 1 from the measured abundance value Med sand to the abundance set value Consrich sand, during the validity of at least one of the predetermined operating conditions cond1 to condx in the engine 1.

According to the invention, the nominal adjustment dynamic Dyn nom of the abundance Med sond sam is replaced by a modified adjustment dynamic Dyn fin specific to said at least one condition cond1 to condx. The measured abundance Med sam refers to the actual abundance at the measurement point at which the measurement is performed. This actual abundance can also be estimated.

For example, in fig. 4, in a non-limiting specific example of the invention, it is shown that the measured abundance Med sond sam has a deviation Err with respect to the abundance set value Consrich prob. If the nominal correction dynamics Dyn nom is too fast, this correction can oscillate the actual abundance around an abundance setpoint Consrich sond, which is referred to here as the abundance setpoint at the so-called upstream probe 1, which is present in the exhaust line of the engine 1 upstream of the catalyst 3, but this is not limitative.

In fig. 4, the abundance set value at the engine 1 actually shown by the curve Consrich mot is replaced by the abundance set value estimated at the probe based on the abundance set value Consrich mot at the engine, and since the probe detects the measured abundance Med sond sam, the abundance set value Consrich sond and the measured abundance Med sond sam are compared at the same point of the exhaust line so that the comparison does not occur erroneously. However, the presence of such a detector is not essential to the practice of the invention.

In practice, the dynamic Dyn nom rating is likely not well adapted to the specific operating condition or conditions cond1 to condx. Within the scope of the present invention, there may be multiple operating conditions cond1 through condx that require dynamic modifications, which may be different. In this case, particular embodiments of the present invention may choose between various dynamics in order to select the most advantageous dynamic modification. As will be described in more detail below.

Still according to the invention, when a preliminary test is carried out on the engine 1 relating to the adjustment of the predetermined abundance setpoint Consrich sond at the engine 1, one or more operating conditions cond1 to condx are selected and identified which currently require a modification of the nominal dynamic Dyn nom when the engine 1 is running. For example, it may be observed that the actual abundance oscillates too much around the abundance setpoint Consrich sond, or that certain operating parameters of the engine 1 cannot be adopted, since the nominal dynamic Dyn nom is not suitable for the particular case caused by one or more of the specific operating conditions cond1 to condx of the engine 1.

One or more specific operating conditions cond1 to condx requiring modification of the dynamic Dyn fin are identified by calibrating at least one value of at least one operating parameter Tb of the engine 1, which value represents that the identified one or more operating conditions cond1 to condx are valid. The parameter Tb shown in fig. 3 is the sweep rate, however one or more other parameters may be considered to characterize the particular operating conditions that require modification of dynamic Dyn fin. These values are set at the time of engine development and applied according to defined conditions.

The value of the at least one parameter Tb characterizes and indicates that the operating condition or operating conditions cond1 to condx requiring a modification of the correction with dynamic Dyn nom rating is valid.

Once this at least one value is detected at a given moment of operation of the engine 1, the nominal dynamic Dyn nom is corrected according to the weighting term Fpond to give a modified dynamic Dyn fin. The correction continues as long as the at least one value is detected. Then, returning to the nominal dynamic Dyn nom, the nominal dynamic is the default dynamic when any of the operating conditions cond1 to condx requiring modification of the corrected abundance with the nominal dynamic Dyn nom is invalid.

Fig. 2 shows an embodiment of the present invention. The adjustment means M forming the adjustment module determine the correction term Fpond on the basis of one or more operating conditions cond1 to condx, in particular by means of a one-dimensional or multidimensional map, taking into account whether one or more operating conditions cond1 to condx are valid which require a modification of the nominal dynamic Dyn nom for the correction.

The weighting term Fpond is sent to the nominal dynamic Dyn nom to give a modified dynamic Dyn fin. Preferably, the weighting term Fpond may be a multiplication factor applied to the nominal dynamics Dyn nom. In addition to one or more parameters directly identifying the operating conditions cond1 to condx requiring modification of the nominal dynamic Dyn nom for correcting the abundance, the weighting term Fpond may be calibrated on the basis of other parameters, such as, but not limited to, the speed of the engine or the filling rate of one or more cylinders of the engine.

The one or more conditions may be taken from, or generated from, the following parameters, alone or in combination: a scavenging rate Tb, scavenging is performed in the engine 1 with fresh air and unburned air is taken into the exhaust pipe at the outlet of the engine 1; the temperature of the coolant of the engine 1, which represents the temperature of the engine 1; performing at least one diagnosis of the engine 1 or the exhaust pipe; testing the engine 1; alternatively, a model is tested for matching, which model is associated with a measurement sensor present in the pollution control element or in the exhaust line.

For example, the measuring sensor model may be a model of a probe, advantageously an upstream probe 4a connected to the catalyst 3 in the exhaust line of the engine 1, which upstream probe 4a may also be used to compare the measured abundance Med sond sam with an estimated abundance setpoint Consrich sond at the upstream probe 4a in the exhaust line. The presence of this upstream probe 4a is not essential to the implementation of the invention, but is nevertheless reasonable.

In addition to the scavenging rate Tb, the rotational speed of the engine may also be considered. As shown in fig. 3, the lower the engine speed is, the smaller the absolute value of the abundance deviation Err rich is for the same scavenging rate Tb. The engine speed can therefore be considered as a further value associated with the scavenging rate Tb, for example to calibrate the weighting term Fpond. This is not necessary.

In FIG. 3, three curves are shown for three different engine speeds, i.e., 1750, 1550 and 1000 revolutions per minute. The dynamics used to correct the abundance deviation Err may be higher and may no longer correspond to the desired optimal dynamics under certain conditions. This is not essential within the scope of the invention.

Fig. 3 shows the abundance deviation Err rich for different sweep rates Tb from-5% to 20%. If the scavenging rate Tb lower than 5% is not considered, it can be seen that the two scavenging curves at the engine speed RM of 1750 revolutions per minute and 1550 revolutions per minute gradually decrease, the scavenging rate Tb gradually increases, and thus the absolute value of the abundance deviation Err rich becomes larger as the abundance deviation Err rich starts to take a value from 0.

These abundance deviations Err rich may reach-2.25 for a scavenging rate Tb of 20% for an engine speed RM of 1750 revolutions per minute and-0.25 for a scavenging rate Tb of 20% for an engine speed RM of 1550 revolutions per minute. The abundance deviation Err rich is equal to 0.1 and slightly greater than 0 for an engine speed RM of 1000 revolutions per minute and a scavenging rate Tb of 13%. Thus, the correction dynamics from the actual abundance measurement to the set point for abundance can vary depending on engine speed in combination with one or more other parameters.

In conducting the test, a series of weighting terms Fpond may be determined for similar test sets. Each of the weighting terms Fpond may be associated with one of the tests and used to correct the nominal dynamic Dyn nom during that test. Therefore, a correction dynamic personalization is performed for a specific test, which is optimal.

As shown in fig. 2, at least two predetermined operating conditions cond1 through condx of engine 1 may be simultaneously active by each being associated with a respective weighting term Fpond. In this case, a weighting term can be selected among the two weighting terms Fpond with being the smaller of the two weighting terms Fpond.

The measuring sensor can be a probe, so-called upstream probe 4a, which is arranged in the exhaust line at the outlet of the heat engine 1. In this case, the adjustment of the abundance can be made by comparing the abundance set value Consrich send estimated at the upstream probe 4a with the abundance value Med send sam measured at the upstream probe 4a, which adjusts one or more parameters of the engine 1 based on the predetermined abundance set value Consrich mot at the engine so that the measured abundance value Consrich send follows the abundance set value Consrich send estimated at the upstream probe 4 a.

Referring to fig. 1 and 4, the estimated abundance set value Consrich sond at the upstream probe 4a is modeled based on a predetermined abundance set value Consrich mot at the engine by taking into account the delay time ttrans of the upstream probe 4a, which delay time ttrans of the upstream probe 4a depends on the distance between the engine 1 and the upstream probe 4a and the velocity of the exhaust gas currently at the outlet of the engine 1, and the reaction time treps to reach the abundance of 0.63 or to correspond to the upstream probe 4a with an abundance of 63%.

Thus, the modeling is based on the identification of two characteristic times, the delay time ttrans and the reaction time treps of reaching 63%. These parameters can be defined in terms of operating points and calibrated through maps.

In fig. 4, the abundance R is on the ordinate, while the time t is on the abscissa. A curve of the set value Consrich mot at the engine and two curves of the abundance set value Consrich sond at the upstream probe and the upstream probe measurement value Mes sond sam are shown. The abundance set at the upstream detector, Consrich sond, is the detector abundance set that is filtered and changed.

There is a deviation Err between the two curves, the Mes + sam curve for the detector measurement abundance and the filtered detector abundance set, Consrich + sand, respectively. The estimated abundance setpoint Consrich sond at the upstream probe 4a based on the abundance of the engine 1 is advantageously filtered by a 1 st order filter.

The invention also relates to a powertrain comprising a heat engine 1 and a command control unit responsible for the operation of the heat engine 1, which unit is not shown in the figures. The command and control unit comprises means for regulating or controlling the nominal dynamic Dyn nom, which means are used to adjust the abundance measurement Mes sand, i.e. the actual abundance value of the air/fuel mixture in the heat engine 1 at a given moment, to the abundance setpoint Consrich sand. The regulating device can be part of an abundance regulator which performs the control of the measured actual abundance value to the abundance setpoint Consrich sond.

According to the invention, the command control unit comprises means for implementing the modification method of the correction dynamics as described previously. The command control unit comprises calibration means for calibrating at least one value of at least one operating parameter Tb of the engine 1, which at least one parameter represents at least one predetermined operating condition cond1 to condx of the engine 1, which operating condition, when valid, requires a correction of the adjustment dynamics of the abundance set point Consrich sond.

The command control unit further comprises calculation means for calculating a weighting term Fpond to be applied on the current dynamic to give a modified dynamic Dyn fin, and tracking means for tracking at least one parameter for implementing a correction when at least one value of the at least one parameter Tb is valid. It is also possible to use a calibratable auxiliary value for modifying the dynamics, which is related to the at least one value.

For example, there may be a start value for starting dynamic modification and an abort value for aborting dynamic modification that is close to the start value but set to require less dynamic modification.

The powertrain may comprise at least one catalyst 3 integrated in the exhaust line at the outlet of the heat engine 1. An upstream probe 4a and a downstream probe 4b are provided upstream and downstream of the catalyst 3, respectively, and the upstream probe 4a can be used to correct the measured abundance Med sand to the abundance set value Consrich sand. The command and control unit can also be responsible for the decontamination in the exhaust line by acting on the decontaminating element.

Catalyst 3 may be a three-way redox catalyst, upstream probe 4a being a proportional oxygen probe and downstream probe 4b being a binary oxygen probe, the probes being located upstream and downstream of the catalyst, respectively.

The invention is not limited to the described and shown embodiments which are given by way of example only.

Claims

1. Method for modifying the adjustment dynamics for adjusting the measured abundance (Med Sond sam) of an air/fuel mixture in a heat engine (1) to an abundance set-point (Consrich Sond) when at least one operating condition (cond1 to condx) of the engine (1) is active, characterized in that the nominal adjustment dynamics (Dyn nom) of the abundance (Med Sond sam) are replaced by modification adjustment dynamics (Dyn fin) specific to the at least one condition (cond1 to condx), the at least one condition (cond1 to condx) being chosen by calibrating at least one value of at least one operating parameter (Tb) of the engine (1) representing that the at least one condition (cond1 to condx) is active when the engine (1) is subjected to a preliminary test in relation to the adjustment of the predetermined abundance set-point (Consrich Sond) at the engine (1), and, upon detection of said at least one value at a given moment of operation of said engine (1), correcting said nominal dynamics (Dyn nom) according to a weighting term (Fpond) to give said modified dynamics (Dyn fin) when said at least one value is detected,

at least two predetermined operating conditions (cond1 to condx) of the engine (1) are simultaneously active when the predetermined operating conditions are each associated with a respective weighting term (Fpond), the selected one of the two weighting terms (Fpond) being the smaller of the two weighting terms (Fpond).

2. The method according to claim 1, wherein said at least one condition (cond1 to condx) is selected from the following parameters, alone or in combination: a scavenging rate (Tb) for scavenging air in the engine (1) with fresh air and allowing unburnt air to enter an exhaust line at the outlet of the engine (1); -the temperature of the coolant of the engine (1) representing the temperature of the engine (1); -performing at least one diagnosis of the engine (1) or the exhaust line; the engine (1) is tested or adjustments to a model relating to a decontaminating element (3) or a measuring sensor (4a, 4b) present in the exhaust line are tested.

3. Method according to claim 2, wherein, in carrying out a test, a series of weighting terms (Fpond) are determined for a set of similar tests, each of said weighting terms (Fpond) being associated with each of said tests and being used to correct said nominal dynamics (Dyn nom) during said test.

4. Method according to claim 2, wherein said measuring sensor is a so-called upstream probe (4a) placed upstream of said decontaminating element (3) in said exhaust line at the outlet of said heat engine (1).

5. Method according to claim 4, wherein the abundance adjustment is made by comparing an estimated abundance set value (Consrich sand) at the upstream probe (4a) based on a predetermined abundance set value (Consrich mot) at the engine with a measured abundance (Med sand sam) measured by the upstream probe (4a), adjusting one or more parameters of the engine (1) so that the measured abundance (Med sand sam) follows the estimated abundance set value (Consrich sand) at the upstream probe (4 a).

6. Method according to claim 5, wherein the abundance set (Consrich Sond) at the upstream probe (4a) is modeled from the engine predetermined abundance set (Consrich mot) by taking into account the delay time (ttrans) of the upstream probe (4a), depending on the distance between the engine (1) and the upstream probe (4a), and the current velocity of the exhaust gases at the outlet of the engine (1), and in particular the reaction time (treps) for the upstream probe (4a) with an abundance of 0.63.

7. Method according to any one of claim 1, characterized in that said weighting term (Fpond) is obtained by means of an x-dimensional map, x being equal to 1 for a single predetermined operating condition (cond1 to condx), or x being equal to the total number of predetermined operating conditions (cond1 to condx).

8. Method according to any one of claim 1, characterized in that said weighting term (Fpond) is a multiplication factor applied to said nominal dynamics (Dyn nom).

9. A powertrain comprising a heat engine (1) and a command control unit in charge of controlling the operation of the heat engine (1), the command control unit having an adjusting device for adjusting a nominal trim dynamics (Dyn nom) for adjusting a measured abundance (Mes + sam) of an air/fuel mixture in the heat engine (1) to an abundance set value (Consrich +), characterized in that the command control unit comprises means for implementing a modification method according to any one of claims 1 to 8, the command control unit comprising: -calibration means for calibrating at least one value of at least one operating parameter (Tb) of the engine (1) representative of at least one predetermined operating condition (cond1 to condx) of the engine (1) which, when active, requires a correction of the regulation dynamics of the abundance setpoint (Consrich sond); -computing means for computing a weighting term (Fpond) to be applied to the current nominal dynamics (Dyn nom) to give a modified dynamics (Dyn fin); and tracking means to track said at least one parameter (Tb) to effect a correction when at least one value of said at least one parameter (Tb) is valid.