EP-4735742-A1 - METHOD FOR ESTIMATING THE AMOUNT OF POLLUTING SPECIES IN THE EXHAUST GAS OF AN INTERNAL COMBUSTION ENGINE, PROVIDED WITH AT LEAST ONE THREE-WAY CATALYST

Abstract

A method for estimating the amount of polluting species in the exhaust gases of a motor vehicle equipped with an internal combustion engine and at least one three-way catalyst, the estimation method making it possible to estimate the amount of polluting species in the exhaust gases, in particular before a possible concentration sensor is hot enough to carry out measurements, comprising the following steps: a. the chemical reactions are identified (1) in the at least one three-way catalyst having the polluting species as a reactant or product, b. the reaction rates of each identified chemical reaction are determined (2), c. a mass balance is carried out (3) in the at least one catalyst considered as an open system, for each polluting species, and d. the amount of polluting species in the exhaust gas is determined (4) as a function of the mass balance.

Inventors

• ARRANZ-VELASCO, Adolfo
• VILLAIN, NATHALIE

Assignees

• Horse Powertrain Solutions, S.L.U.

Dates

Publication Date

20260506

Application Date

20240627

Claims (1)

1. CLAIMS 1. Method for estimating the amount of polluting species in the exhaust gas of a motor vehicle provided with an internal combustion engine and at least one first three-way catalyst, the estimation method making it possible to estimate the amount of polluting species in the exhaust gas, in particular before a possible concentration sensor is hot enough to carry out measurements, the method comprising the following steps: a. the chemical reactions involved in the first three-way catalyst are identified, having as reagent or product the polluting species whose amount in the exhaust gases must be estimated, b. the reaction rates of each identified chemical reaction are determined, c. a mass balance is carried out in the first catalyst considered as an open system, for each of the polluting species whose quantity is to be determined, and d. the amount of polluting species in the exhaust gas is determined as a function of the mass balance. 2. Estimation method according to claim 1, wherein the polluting species are nitric oxide and ammonia, the estimation method comprising the following steps: a. the temperature in the first catalyst, the flow rate in the first catalyst, and the torque of the internal combustion engine are determined, b. the molar fraction of nitric oxide in the gases leaving the internal combustion engine is determined by applying a first mapping as a function of the estimated torque of the engine, c. the molar fraction of nitrogen oxides in the gases leaving the first catalyst, arranged downstream of the internal combustion engine, is determined as a function of the molar fraction of nitric oxyde produced by the engine, the flow rate in the first catalyst and the volume of the first catalyst, as well as a second 1D mapping dependent on the temperature in the first catalyst and a third 1D mapping dependent on the flow rate in the first catalyst, d. the molar fraction of ammonia in the gases leaving the first catalyst is also determined, as a function of a fourth 1D mapping dependent on the temperature in the first catalyst and the molar fraction of nitrogen oxides in the gases issued by the internal combustion engine. 3. Estimation method according to claim 2, wherein, when the motor vehicle is provided with a second three-way catalyst upstream of the first three-way catalyst, the method comprises the following steps: a. the molar fraction of ammonia in the gases leaving a second catalyst is determined as a function of a fifth temperature-dependent 1D mapping in the second catalyst and as a function of the value of the number of ammonia adsorption sites, b. the molar fraction of nitric oxide in the gases leaving the second catalyst is determined as a function of the molar fraction of nitric oxide in the gases leaving the first catalyst, the flow rate in the second catalyst and the volume of the second catalyst, as well as a sixth temperature-dependent 1D mapping in the second catalyst and a seventh flow-dependent 1D mapping in the second catalyst. 4. Estimation method according to claim 2 or 3, wherein the mappings are calibrated as a function of the measurements made during tests. 5. Estimation method according to claim 1, wherein the polluting species are carbon dioxide ^^ ^ , carbon monoxide CO, hydrocarbons HC, ammonia ^^ ^ , nitric oxide NO, nitrogen dioxide ^^ ^ or nitrous oxide ^ ^ ^. 6. Motor vehicle equipped with an estimation system configured so as to carry out the estimation method according to any one of claims 1 to 5, in particular within an on-board diagnosis. 7. Motor vehicle according to claim 6, further comprising a partial exhaust gas recirculation circuit at the intake.

Description

DESCRIPTION Method for estimating the amount of polluting species in the exhaust gas of an internal combustion engine, provided with at least one three-way catalyst. TECHNICAL FIELD The technical field of the invention is the estimation of the polluting species produced by an internal combustion engine, and more precisely, the polluting species produced by an internal combustion engine provided with at least one catalyst. PRIOR ART The new Euro 7 standard, which will come into force from 2025, requires a reduction in pollutant emissions, compared to the current standard (Euro 6e), for vehicles marketed in Europe. Among the polluting emissions, the Euro 7 standard is particularly strict with regard to emissions of nitrogen oxides ^^^ and ammonia ^^^. Among these gases, the particularities of the ^^^ and of the ^^^ are noted. Nitrogen dioxide ^^^ is a toxic gas that produces inflammation of the respiratory tract and contributes to the formation of acid rain. Ammonia ^^^ contributes to the formation of secondary particles, associated with cardiovascular and respiratory diseases, and is harmful to aquatic environments. The Euro 7 standard comprises an OBM (English acronym for "On-Board Monitoring") on-board diagnostic obligation. It will be mandatory to monitor, on each journey made by the vehicle, the amount of nitrogen oxides ^^^ (mainly nitrogen monoxide ^^ and nitrogen dioxide ^^^) and the amount of ammonia ^^^ emitted at the exhaust. The vehicle will have to transmit these values not only via the OBD (On- Board Diagnostic) socket but also via OTA (Over the Air) wireless communication to a dedicated platform. If the emissions of nitrogen oxides ^^^ or ammonia ^^^ exceed a predefined limit, built by multiplying the regulatory threshold of the species considered by a predetermined factor greater than 1, called conformity factor CF, then the vehicle must alert the driver by lights on the dashboard and impose the repair of the vehicle via engine torque and vehicle speed limitations, or even by the prohibition of starting. In other words, if the emissions are greater than, for example, 1.5 or 2 times more than predetermined thresholds, generally obtained during the approval of the vehicle, calculated on a number of valid journeys, the alert must be given. In order to determine these values, a concentration sensor to determine the concentration of these pollutants in the exhaust gases must be provided in vehicles seeking Euro 7 approval. An on-board sensor diagnostic system is also required. However, existing types of sensors are not capable of carrying out a measurement as long as their sensitive element has not yet reached a threshold temperature, called the operating temperature. The temperature rise of the sensor can last up to 90 seconds from the start of driving for spark-ignition vehicles. It thus appears that it is not possible to meet the Euro 7 standard with the only existing sensors because of the absence of measurement until 90 seconds after the start of driving. There is a need for a determination of the emissions of nitrogen oxides and ammonia at the exhaust outlet of a controlled internal combustion engine, before the operating temperature is reached by the sensor for measuring these pollutants. In the prior art, many documents deal with estimating the amount of nitrogen oxides. Mention may be made in particular of documents US8225595, US20170044962, US9771846, US9304061, EP2832965, EP2910758 and EP3819483 dealing with the specific case of diesel engines, which does not apply to the present problem. Mention may also be made of the documents US11028753, JP2009287410, US2008/108212 and WO2016/159019A1 describing models for determining the amount of nitrogen oxides but only at the engine outlet, and not at the exhaust outlet after the after treatment device (s). Documents EP3736418 and EP3956549 disclose models for estimating these emissions as a function of the measurement of sensors. These documents are inapplicable here due to the impossibility of taking a measurement until the sensor has reached its operating temperature. The technical problem is therefore not solved by the prior art. EXPLANATION OF THE INVENTION The subject of the invention is a method for estimating the amount of polluting species in the exhaust gases of a motor vehicle provided with an internal combustion engine, and with at least one first three-way catalyst, the estimation method making it possible to estimate the amount of polluting species in the exhaust gases, in particular before a possible concentration sensor is hot enough to carry out measurements, the method comprising the following stages: the chemical reactions involved in the first three-way catalyst are identified, having as reagent or product the polluting species whose amount in the exhaust gases must be estimated, the reaction rates of each identified chemical reaction are determined, a mass balance is carried out in the first catalyst considered as an op