EP2765290A1 - Method for estimating the temperature of exhaust gas - Google Patents

Abstract

The method involves determining an inlet temperature (T2) of exhaust gas entering a combustion chamber (21), and determining total amount of fuel injected into the combustion chamber (20). Temperature (T3) of the exhaust gas is estimated (22) from the inlet temperature and the total amount of injected fuel, where the temperature of the exhaust gas is estimated based on a relation logarithmic curve between a ratio of the temperature of the exhaust gas by the inlet temperature and the total amount of injected fuel. Independent claims are also included for the following: (1) an estimator for estimating temperature of exhaust gas produced by an internal combustion engine (2) a vehicle.

Description

Technical field of the invention

The present invention relates to a method for estimating the temperature of the exhaust gases produced by an internal combustion engine.

Technological background

The constraints due to standards, for example the European standards known as Euro VI, relating to the levels of polluting emissions generated by the operation of internal combustion engines, in particular Diesel, are becoming more and more severe.

The performance levels required for the engine control functions are therefore increasingly demanding, so it is interesting to know the state of the system to control. This knowledge currently goes through the implantation of sensor completed by a modeling of the physical phenomena present.

A specific quantity of the system can then be estimated via the measurement of the sensor and the result of the modeling. These two sources of information have different qualities: reliability, dynamics ...

Modeling estimation of the exhaust gas temperature, taken as close as possible to the outlet of the combustion chamber, in practice in the exhaust manifold of a heat engine, is one of the main variables of the engine control. This estimate is used in particular for the estimation of other temperatures at other points of the exhaust line, these estimates being necessary for the control of pollution control member such as for example a particle filter or a catalyst.

There are in the industrial field devices giving the temperature in the exhaust manifold, for example temperature sensors or thermocouples.

The use of temperature sensors or thermocouples is limited: a compromise between response time and fouling must be made. Indeed the lower the response time of the sensor, the smaller it is and sensitive to fouling.

Immediately leaving the combustion chamber of a heat engine, in particular of the Diesel type, the exhaust gases contain particles which contribute to the fouling. These particles therefore limit the use of a sensor with a low response time.

There are also methods for estimating the temperature in the exhaust manifold. We know, for example, of the document US20093989A1 a method for estimating the temperature of the exhaust gas as a function of the temperature of the intake air, the quantity of heat supplied by the combustion of the injected fuel and the air coefficient measured by the so-called lambda in the exhaust line downstream of the exhaust manifold.

Such a method allows a low response time, but remains dependent on the proper functioning of the lambda probe and is therefore insufficiently reliable and accurate to meet the standards of pollution control, in particular Euro 6.

There is therefore a need to estimate the temperature of the exhaust gas at the exhaust manifold accurately and with low response time.

• détermination de la température d'admission des gaz entrant dans la chambre de combustion,
• détermination de la quantité totale de carburant injectée dans la chambre de combustion,
• estimation de la température des gaz d'échappement à partir de la température d'admission et de la quantité totale de carburant injectée,

caractérisé en ce que la température des gaz d'échappement est estimée à partir d'une relation logarithmique entre le ratio de la température des gaz d'échappement par la température d'admission et la quantité totale de carburant injectée.To achieve this objective, it is provided according to the invention a method for estimating the temperature of the exhaust gas produced by an internal combustion engine comprising a combustion chamber into which a total quantity of fuel is injected, the method comprising the steps of:

• determination of the admission temperature of the gases entering the combustion chamber,
• determination of the total quantity of fuel injected into the combustion chamber,
• estimating the temperature of the exhaust gas from the intake temperature and the total quantity of fuel injected,

characterized in that the temperature of the exhaust gas is estimated from a logarithmic relationship between the ratio of the exhaust gas temperature by the intake temperature and the total amount of fuel injected.

• détermination pour chaque injection distincte d'un coefficient de pondération prenant en compte la contribution de la quantité de carburant injectée au cours de chaque injection à la modification de la température des gaz,
• Détermination pour chaque injection d'une quantité de carburant injectée pondérée à partir du coefficient de pondération et de la quantité de carburant injectée,
• détermination d'une quantité totale de carburant pondérée à partir de la somme des quantités injectées pondérées à la place de l'étape de détermination de la quantité totale de carburant injectée,
• Utilisation de la quantité totale de carburant pondérée à la place de la quantité totale de carburant injectée au cours de l'étape d'estimation de la température des gaz d'échappement.

In a variant where the total quantity of fuel is injected into the combustion chamber in at least two distinct injections, the method comprises the steps of:

• determination for each separate injection of a weighting factor taking into account the contribution of the quantity of fuel injected during each injection to the change in the temperature of the gases,
• Determination for each injection of a quantity of injected fuel weighted from the weighting coefficient and the quantity of fuel injected,
• determining a total quantity of weighted fuel from the sum of the weighted injected quantities in place of the step of determining the total amount of fuel injected,
• Use of the total amount of weighted fuel in place of the total amount of fuel injected during the exhaust gas temperature estimation step.

Preferably the method comprises a step of determining a fuel injection sequence establishing the distribution of the total amount of fuel injected on each separate injection.

Preferably, the weighting coefficient has a first sign if the fuel injection contributes to an increase in the temperature of the exhaust gas or an opposite sign if the fuel injection contributes to a decrease in the temperature of the exhaust gas. .

More preferably, the weighting coefficients are between 1 and -1.

In a variant where one of the distinct injections is a so-called main injection during which the largest fraction of the total quantity of fuel is injected, the weighting coefficient of the main injection is equal to 1.

• Avec β et γ des coefficients de régression prédéterminés.
• T3 la température des gaz d'échappement à estimer,
• T2 la température d'admission des gaz entrant dans la chambre de combustion, Qtot_carb, la quantité totale de carburant injectée.

Preferably, the logarithmic relation between the ratio of the exhaust gas temperature by the intake temperature and the total amount of fuel injected is of the form: $$\frac{\mathrm{T}\mathrm{3}}{\mathrm{T}\mathrm{2}}=\mathrm{\beta }\cdot \ln \left({\mathrm{Q}}_{\mathrm{tot\_carb}}\right)+\mathrm{\gamma }$$

• With β and γ predetermined regression coefficients.
• T3 the temperature of the exhaust gas to be estimated,
• T2 the inlet temperature of the gases entering the combustion chamber, Qtot_carb, the total quantity of fuel injected.

Preferably, the regression coefficients β and γ are determined from a preliminary engine test campaign to determine the temperature ratio as a function of the total amount of fuel injected, said quantity of fuel being injected in a single main injection.

The subject of the invention is also an estimator of the temperature of the exhaust gases produced by an internal combustion engine, characterized in that it comprises the acquisition and processing means required for carrying out the process according to the invention. any of the previously described variants.

The invention also relates to a vehicle equipped with an internal combustion engine, characterized in that it comprises an estimator of the temperature of the exhaust gas produced by said internal combustion engine of the invention.

Brief description of the drawings

• La figure 1 est une représentation schématique d'un moteur à combustion interne relié à une ligne d'échappement.
• La figure 2 est une représentation schématique sous forme de logigramme du procédé de l'invention.
• La figure 3 présente un exemple de séquence d'injection de carburant au cours d'un cycle moteur. En ordonnée est représentée la quantité de carburant injectée, Qcarb, et en abscisse le temps, t.

Other features and advantages will appear on reading the following description of a particular embodiment, not limiting of the invention, with reference to the figures in which:

• The figure 1 is a schematic representation of an internal combustion engine connected to an exhaust line.
• The figure 2 is a schematic representation in the form of a logic diagram of the method of the invention.
• The figure 3 shows an example of a fuel injection sequence during a motor cycle. In ordinate is represented the quantity of injected fuel, Qcarb, and in abscissa the time, t.

detailed description

The figure 1 schematically shows an internal combustion engine 1, including a diesel type direct injection engine that can equip a vehicle. The engine 1 typically comprises at least one combustion chamber 2 for receiving the air and the fuel required for combustion. On the figure 1 , four combustion chambers are shown, but the engine may include a different number of combustion chamber. The engine 1 is connected to an intake air distributor 3 allowing the distribution of intake air in the combustion chambers 2. The motor 1 is also connected to an exhaust manifold 4 for evacuation of the exhaust gases from the combustion chambers 2. The exhaust manifold 4 is connected to an exhaust line 5 so as to allow the transfer of the gases exhaust combustion chambers 2 to the exhaust line 5.

The engine 1 may be supercharged in which case the exhaust line 5 may comprise a turbocharging turbine 6. The exhaust line 5 may also comprise at least one depollution device such as an oxidation catalyst 7, a selective reduction catalyst 8 of nitrogen oxides, a particulate filter 9.

The engine 1 may further comprise an exhaust gas recirculation loop 10 for taking a fraction of the exhaust gas and returning it to the intake. The flow of exhaust gas in the recirculation loop 10 can be controlled by a valve 11.

• T3 désigne la température des gaz d'échappement produits par le moteur 1 à combustion interne. En pratique, T3 correspond à la température des gaz d'échappement pris au plus près de la sortie de la chambre de combustion, en pratique vu au niveau du collecteur 4 d'échappement, car à cet endroit les gaz d'échappement provenant des différentes chambres de combustion 2 se sont homogénéisés.
• T2 désigne la température des gaz entrant dans les chambres de combustion 2. Les gaz entrant peuvent être de l'air ou encore un mélange d'air et de gaz d'échappement dans le cas où une boucle de recirculation 10 est présente. En pratique T2 correspond à la température des gaz entrant vu au niveau du répartiteur d'air d'admission 3.

On the figure 1 again :

• T3 denotes the temperature of the exhaust gases produced by the internal combustion engine 1. In practice, T3 corresponds to the temperature of the exhaust gas taken closer to the outlet of the combustion chamber, in practice seen at the level of the exhaust manifold 4, because at this point the exhaust gases from different combustion chambers 2 have become homogenized.
• T2 designates the temperature of the gases entering the combustion chambers 2. The incoming gases may be air or a mixture of air and exhaust gas in the case where a recirculation loop 10 is present. In practice T2 corresponds to the incoming gas temperature seen at the intake air distributor 3.

• une injection dite principale, Iprinc, car y est injectée la plus importante fraction de la quantité totale de carburant, Qtot_carb, pour la génération du couple moteur,
• une injection secondaire, Isp, succédant l'injection principale permettant de réduire les bruits de combustion,
• une première et une seconde injection pilote, Ipil1 et Ipil2, précédant l'injection principale et permettant aussi de réduire les bruits de combustion,
• une première et seconde post injection, Ipost1 et Ipost2, succédant à l'injection secondaire permettant d'assister les systèmes de post-traitement de la ligne d'échappement.

When the engine 1 is in operation, at each engine cycle, a total amount of fuel, Qtot_carb is injected into the combustion chamber. The total amount of fuel, Qtot_carb, can be split into at least two separate injections in a fuel injection sequence establishing the distribution Qi of the total amount of fuel, Qtot_carb, on each distinct injection i. The roles of these injections are multiple: reduction of the noise of combustion, post-treatment, torque, rise in temperature of the exhaust gases. figure 3 presents a non-limiting example of a fuel injection sequence on a diesel engine comprising six fuel injections. More specifically, the injection sequence of the figure 3 includes:

• a so-called main injection, Iprinc, because it is injected the largest fraction of the total amount of fuel, Qtot_carb, for the generation of the engine torque,
• a secondary injection, Isp, succeeding the main injection making it possible to reduce the combustion noises,
• a first and a second pilot injection, Ipil1 and Ipil2, preceding the main injection and also making it possible to reduce the combustion noise,
• a first and second post injection, Ipost1 and Ipost2, succeeding the secondary injection to assist the after-treatment systems of the exhaust line.

The figure 2 now presents in the form of a flowchart the main steps of the method of the invention for estimating the temperature T3 of the exhaust gas.

In step 20, a total quantity of weighted fuel, Qtot_carb_pond, is determined. In this step 20 is determined at 20 'the fuel injection sequence establishing the distribution Qi on each injection i of the total amount of fuel, Qtot_carb injected. The injection sequence can be determined as a function of engine operating parameters such as engine speed and load. This total weighted fuel quantity, Qtot_carb_pond, is determined by the following relation: $${\mathrm{Q}}_{\mathrm{tot\_carb\_pond}}=\Sigma {\mathrm{\alpha }}_{\mathrm{i}}\cdot {\mathrm{Q}}_{\mathrm{i}}$$

With Qi, the quantity of fuel injected during an injection i of the injection sequence (therefore Q _{tot_carb} = Σ Q _i ) and αi a weighting coefficient attributed to the quantity Qi of fuel injected as a function of the contribution of the quantity Qi of fuel on the modification of the temperature of the gases and thus its impact on the temperature T3 of the exhaust gases. These weighting coefficients are determined in step 20 ".

Indeed, it turns out that all injections do not participate in the same way to the rise of the gas temperature. The product α _i · Q _i thus determines the quantity of injected fuel weighted for injection i of the injection sequence. In the case of the injection sequence illustrated in figure 2 we then have: $${\mathrm{Q}}_{\mathrm{tot\_carb\_pond}}={\mathrm{\alpha }}_{\mathrm{1}}\cdot {\mathrm{Q}}_{\mathrm{pil}\mathrm{2}}+{\mathrm{<figure-callout\; id="2"\; label="\alpha "\; filenames="imgf0002.png"\; state="\{\{state\}\}">\alpha </figure-callout>}}_{\mathrm{2}}\cdot {\mathrm{Q}}_{\mathrm{pil}\mathrm{1}}+{\mathrm{<figure-callout\; id="3"\; label="\alpha "\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">\alpha </figure-callout>}}_{\mathrm{3}}\cdot {\mathrm{Q}}_{\mathrm{princ}}+{\mathrm{\alpha }}_{\mathrm{4}}\cdot {\mathrm{Q}}_{\mathrm{sp}}+{\mathrm{\alpha }}_{\mathrm{5}}\cdot {\mathrm{Q}}_{\mathrm{post}\mathrm{1}}+{\mathrm{\alpha }}_{\mathrm{6}}\cdot {\mathrm{<figure-callout\; id="2"\; label="Q\; post\; "\; filenames="imgf0002.png"\; state="\{\{state\}\}">Q\; </figure-callout>}}_{\mathrm{post}}$$

The weighting coefficients α1, α2, α3, α4, α5, α6 are the factors attributed to each injection taking into account the contribution of the quantity of fuel injected during each injection to the temperature rise of the gases.

In order to take into account the case of an injection such as, for example, a late post-injection which would have a cooling effect on the exhaust gases, it is intended to assign a positive weighting coefficient if the quantity of fuel injected promotes the a rise in the temperature of the gases or a negative weighting coefficient if the quantity of fuel injected favors the reduction of the temperature of the exhaust gases.

The weighting coefficients can be between a maximum value, V and its opposite, that is to say +/- V.

These weighting coefficients are preferably determined relative to the main injection, Iprinc, for which a reference weighting coefficient equal to the maximum value V is assigned.

It turns out that choosing as the weighting coefficient of the main injection, Iprinc, the maximum value V = 1 makes it possible to have a total quantity of weighted fuel, Qtot_carb_pond representative of a single-injection combustion. This advantage will be better understood in the rest of the paper. Thus, preferably, the weighting coefficients are between -1 and 1.

In step 21, the temperature T2 of the gases entering the combustion chambers 2 is determined, for example by a sensor or an estimator.

In step 22, the exhaust gas temperature T 3 is estimated from the intake temperature T2 and the total weighted fuel quantity Qtot_carb_pond. More precisely and in accordance with the invention, the temperature T3 of the exhaust gas is estimated from a logarithmic relation between the ratio of the temperature, T3, of the exhaust gases by the intake temperature, T2 and the total quantity of weighted fuel, Qtot_carb_pond, of the form: $$\frac{\mathrm{T}\mathrm{3}}{\mathrm{T}\mathrm{2}}=\mathrm{\beta }\cdot \ln \left({\mathrm{Q}}_{\mathrm{tot\_carb\_pond}}\right)+\mathrm{\gamma }$$

With, β and γ regression coefficients. The coefficients β and γ are advantageously determined experimentally during a preliminary motor test campaign. The engine tests aim to determine the temperature ratio T3 / T2 as a function of the total amount of fuel injected, Qtot_carb, said quantity being injected in a single main injection. In this case, the total quantity of fuel injected, Qtot_carb, and the total amount of weighted fuel, Qtot_carb_pond are identical because the weighting coefficient of the main injection is assigned a value of 1.

The figure 4 presents the cloud of points constituting such engine tests and the logarithmic regression curve 40 of form: $$\frac{\mathrm{T}\mathrm{3}}{\mathrm{T}\mathrm{2}}=\mathrm{\beta }\cdot \ln \left({\mathrm{Q}}_{\mathrm{tot\_carb}}\right)+\mathrm{\gamma }$$

In this case, the regression coefficients obtained are illustrated in figure 4 β = 0.71 and γ = 0.38, with a coefficient of determination R ² = 0.95.

• Ajout dans la séquence d'injection de la première injection pilote, Ipil1 à l'injection principale, Iprinc. La quantité totale de carburant pondérée s'écrit alors : $${\mathrm{Q}}_{\mathrm{tot\_carb\_pond}}={\mathrm{<figure-callout\; id="2"\; label="\alpha "\; filenames="imgf0002.png"\; state="\{\{state\}\}">\alpha </figure-callout>}}_{\mathrm{2}}{\mathrm{Q}}_{\mathrm{pil}\mathrm{1}}+{\mathrm{<figure-callout\; id="3"\; label="\alpha "\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">\alpha </figure-callout>}}_{\mathrm{3}}{\mathrm{Q}}_{\mathrm{princ}}$$
  
  
  avec comme coefficient de pondération de l'injection principale α3 = 1,
• Mesure de la température T2 des gaz entrant dans les chambres de combustion,
• Mesure de la nouvelle température de gaz d'échappement T3',
• Détermination de Qtot_carb_pond à partir de la relation (3) avec les coefficients de régression β et γ fixés lors de la campagne préalable d'essais,
• Détermination du coefficient de pondération de la première injection pilote α2 à partir de la relation (5).

Once the regression coefficients β and γ are fixed in relation (4), the weighting coefficients can then be determined experimentally for any injection sequence. The method is illustrated by taking as an example the case of the first pilot injection, Ipil1:

• Addition in the injection sequence of the first pilot injection, Ipil1 to the main injection, Iprinc. The total amount of weighted fuel is then written: $${\mathrm{Q}}_{\mathrm{tot\_carb\_pond}}={\mathrm{<figure-callout\; id="2"\; label="\alpha "\; filenames="imgf0002.png"\; state="\{\{state\}\}">\alpha </figure-callout>}}_{\mathrm{2}}{\mathrm{Q}}_{\mathrm{pil}\mathrm{1}}+{\mathrm{<figure-callout\; id="3"\; label="\alpha "\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">\alpha </figure-callout>}}_{\mathrm{3}}{\mathrm{Q}}_{\mathrm{princ}}$$
  
  
  with weighting coefficient of the main injection α3 = 1,
• Measurement of the temperature T2 of the gases entering the combustion chambers,
• Measurement of the new exhaust gas temperature T3 ',
• Determination of Qtot_carb_pond from the relation (3) with the regression coefficients β and γ fixed during the preliminary test campaign,
• Determination of the weighting coefficient of the first pilot injection α2 from relation (5).

It is intended to implement the method for estimating the temperature T3 of the exhaust gas of the invention in an estimator such as an electronic computing unit. Advantageously, this estimator comprises the means for acquiring and processing the information required for implementing the method of the invention. These means may comprise in particular means for storing the weighting coefficients, means for storing the injection sequences, these memory means being able to take the form of a map, means for acquiring the temperature T2 of the gases entering the chambers. of combustion, means for determining the total quantity of weighted fuel, Qtot_carb_pond, means for calculating the temperature T3 of the exhaust gases from the intake temperature T2 of the gases and the total quantity of weighted fuel, Qtot_carb_pond , from the logarithmic relation (3).

• détermination à l'étape 21 de la température d'admission, T2, des gaz entrant dans la chambre de combustion 2,
• détermination à l'étape 20 de la quantité totale de carburant, Qtot_carb, injectée dans la chambre de combustion 2,
• estimation de la température, T3, des gaz d'échappement à partir de la température d'admission, T2, et de la quantité totale de carburant, Qtot_carb, injectée, la température, T3, des gaz d'échappement étant estimée à partir de la relation établissant une régression logarithmique entre le ratio de la température, T3, des gaz d'échappement par la température d'admission (T2) et la quantité totale de carburant injectée (Qtot_carb), reprise ici : $$\frac{\mathrm{T}\mathrm{3}}{\mathrm{T}\mathrm{2}}=\mathrm{\beta }\cdot \ln \left({\mathrm{Q}}_{\mathrm{tot\_carb}}\right)+\mathrm{\gamma }$$
  

The invention is not limited to the variants described with a multiple injections injection sequence. In a variant, where the total quantity of fuel is injected in a single injection, thus in a single main injection, the process of the invention becomes:

• determination in step 21 of the inlet temperature, T2, of the gases entering the combustion chamber 2,
• determination in step 20 of the total amount of fuel, Qtot_carb, injected into the combustion chamber 2,
• estimation of the temperature, T3, of the exhaust gases from the intake temperature, T2, and of the total quantity of fuel, Qtot_carb, injected, the temperature, T3, of the exhaust gases being estimated from the relation establishing a logarithmic regression between the ratio of the temperature, T3, of the exhaust gases by the intake temperature (T2) and the total amount of fuel injected (Qtot_carb), repeated here: $$\frac{\mathrm{T}\mathrm{3}}{\mathrm{T}\mathrm{2}}=\mathrm{\beta }\cdot \ln \left({\mathrm{Q}}_{\mathrm{tot\_carb}}\right)+\mathrm{\gamma }$$
  

Indeed, in this case, one uses the total quantity of fuel injected, Qtot_carb, which replaces in the logarithmic relation the total quantity of weighted fuel, Qtot_carb_pond, because the two quantities are identical since one gives the value 1 to the coefficient of weighting of the single injection.

The invention could be suitable for other types of internal combustion engine such as a diesel engine with indirect fuel injection or a spark ignition internal combustion engine.

Claims (10)

A method for estimating the temperature (T3) of the exhaust gas produced by an internal combustion engine (1) comprising a combustion chamber (2) into which a total amount of fuel (Qtot_carb) is injected, the process comprising steps of: determination (21) of the inlet temperature (T2) of the gases entering the combustion chamber, determination (20) of the total amount of fuel (Qtot_carb) injected into the combustion chamber, estimating (22) the temperature (T3) of the exhaust gases from the intake temperature (T2) and the total quantity of fuel (Qtot_carb) injected, characterized in that the temperature (T3) of the exhaust gas is estimated from a logarithmic relationship between the ratio of the temperature (T3) of the exhaust gas to the intake temperature (T2) and the total quantity of fuel (Qtot_carb) injected. The method of claim 1 wherein the total amount of fuel is injected into the combustion chamber in at least two separate injections, characterized in that it comprises the steps of: - determination (20 ") for each distinct injection of a weighting coefficient (αi) taking into account the contribution of the quantity of fuel injected (Qi) during each injection to the modification of the temperature of the gases, - Determination for each injection of a quantity of injected fuel weighted from the weighting coefficient (αi) and the quantity of fuel injected (Qi), - determination of a total quantity of weighted fuel (Qtot_carb_pond) from the sum of the injected quantities weighted in place of the step of determination of the total quantity of fuel (Qtot_carb) injected, - Use of the total amount of weighted fuel (Qtot_carb_pond) instead of the total amount of fuel (Qtot_carb) injected during the step of estimating the temperature (T3) of the exhaust gas. - Method according to claim 2, characterized in that it comprises a step of determining (20 ') a fuel injection sequence establishing the distribution of the total amount of fuel (Qtot_carb) injected on each separate injection. Method according to Claim 2 or Claim 3, characterized in that the weighting coefficient (αi) has a first sign if the fuel injection contributes to an increase in the temperature of the exhaust gas or an opposite sign if the injection fuel contributes to a decrease in the temperature of the exhaust gas. Method according to Claim 4, characterized in that the weighting coefficients (αi) lie between 1 and -1. Process according to Claim 5, characterized in that one of the distinct injections is a so-called main injection during which the largest fraction of the total quantity of fuel (Qtot_carb) is injected, the weighting coefficient of the main injection is equal to 1. Method according to any one of the preceding claims, characterized in that the logarithmic relation between the ratio of the temperature (T3) of the exhaust gases by the intake temperature (T2) and the total amount of fuel injected (Qtot_carb) is of the form: $$\frac{\mathrm{T}\mathrm{3}}{\mathrm{T}\mathrm{2}}=\mathrm{\beta }\cdot \ln \left({\mathrm{Q}}_{\mathrm{tot\_carb}}\right)+\mathrm{\gamma }$$

With β and γ predetermined regression coefficients. Process according to Claim 7, characterized in that the regression coefficients β and γ are determined from a preliminary engine test campaign to determine the temperature ratio as a function of the total quantity of fuel (Qtot_carb) injected, the said quantity fuel being injected in a single main injection. Estimator of the temperature (T3) of the exhaust gases produced by an internal combustion engine (1), characterized in that it comprises the acquisition and processing means required for carrying out the method according to one of the any of the preceding claims. Vehicle equipped with an internal combustion engine (1), characterized in that it comprises an estimator of the temperature (T3) of the exhaust gases produced by said internal combustion engine according to claim 9.

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