MOTOR VEHICLE COMPRISING A MEANS FOR CONTROLLING AN AMMONIA LEAK CATALYTIC CONVERTER AS A FUNCTION OF ITS LOAD AND TEMPERATURE, METHOD AND PROGRAM BASED ON SUCH A VEHICLE
An active management system for ammonia slip catalysts in motor vehicles maintains optimal conditions through temperature and load estimation, ensuring efficient ammonia conversion by preventing leaks and desorption.
Patent Information
- Application Number
- FR2024001702
- Authority / Receiving Office
- FR · FR
- Patent Type
- Patents
- Current Assignee / Owner
- Filing Date
- 2024-02-21
- Publication Date
- 2026-01-02
- Estimated Expiration
- 2044-02-21
AI Technical Summary
Existing ammonia slip catalysts in motor vehicles are passive, leading to ammonia leaks due to inadequate management of catalyst charge, resulting in inefficient ammonia conversion and desorption at high temperatures.
An active management system for the ammonia slip catalyst, utilizing temperature and load estimation, along with control modes to maintain optimal operating conditions, including heating, opportunistic purging, and inhibition strategies to prevent ammonia leakage.
Ensures continuous and efficient ammonia conversion by maintaining the catalyst within the optimal temperature and oxygen conditions, preventing ammonia leaks and desorption.
Smart Images
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Abstract
Description
Title of the invention: MOTOR VEHICLE COMPRISING A MEANS FOR CONTROLLING A CATALYST LEAK AMMONIA DEPENDING ON ITS LOAD AND TEMPERATURE, PROCESS AND PROGRAM BASED ON SUCH A VEHICLE
[0001] The invention relates to the field of control systems after treatment in a motor vehicle with a gasoline engine, and more particularly the management of the ammonia slip catalyst (or "Ammonia slip catalyst" in English).
[0002] The ammonia leak catalyst is designed to store ammonia and convert it in the presence of oxygen. To achieve this, the ammonia leak catalyst must be within a specific temperature range (around 250°C - 450°C). Above 450°C, the ammonia stored in the catalyst could be desorbed without being oxidized.
[0003] In the prior art, the ammonia leak catalyst is a passive part of the exhaust line. Its charge is not managed. As a result, an ammonia leak may occur, meaning that the catalyst is no longer able to store ammonia.
[0004] One objective of the present invention is to overcome the shortcomings of the prior art, and in particular to provide a solution for accurately assessing the charge of the ammonia leak catalyst, in order to determine whether it is still capable of storing ammonia. If not, this results in an interruption of ammonia conversion and ammonia desorption.
[0005] To achieve this objective, the invention proposes a motor vehicle comprising an engine; wheels; an engine acceleration control; an exhaust system equipped with an ammonia leakage catalyst; a temperature estimation means for estimating the catalyst temperature; a load estimation means for estimating the ammonia load of the catalyst; a history estimation means for estimating whether the ammonia load is increasing or decreasing; and a catalyst control means based on control modes among: - a mode without control strategy if the catalyst has a charge below a first charge threshold; or if the catalyst has a charge above the first charge threshold and below a second charge threshold, and has a temperature below a first temperature threshold; - a heating mode if the catalyst has a load greater than the second load threshold and less than a third load threshold, and has a temperature lower than first temperature threshold; or if the catalyst has a charge greater than the third charge threshold, and a temperature lower than the first temperature threshold, and greater than a second temperature threshold, in which a heating means makes a heating demand on the catalyst as a function of a given torque application.
[0006] Advantageously, the invention proposes a control strategy aimed at activating preventive actions to bring the ammonia leak catalyst into good conditions for converting ammonia, namely a good temperature range and a good contribution of oxygen.
[0007] Thus, the invention makes it possible to have an evaluation of the catalyst charge and to optimize the continuous conversion of ammonia, thereby avoiding ammonia leakage and ammonia desorption related to high temperatures.
[0008] Having active management of the catalyst charge allows the catalyst to be in good temperature and oxygen conditions to convert ammonia adequately.
[0009] Preferably, the heating means increases the catalyst temperature to a value between 250°C and 450°C, and for a catalyst heating demand, a minimum torque demand is calculated as a function of: - engine speed; - engine coolant temperature; - a temperature upstream of the catalyst; - the ammonia charge of the catalyst.
[0010] Preferably, the catalyst control means has additional control modes, namely: - an opportunistic purging mode if the catalyst has a load higher than the first load threshold and lower than the second load threshold, and a temperature higher than the first temperature threshold, in which an opportunistic purge means performs a coupling of the motor to the wheels and a drive demand if the throttle control is released; - an active drive and purging mode if the catalyst has a load exceeding the second load threshold, and a temperature exceeding the first temperature threshold, in which a drive means performs a coupling of the engine to the wheels with an injection cut-off.
[0011] Dragging is a request for the gasoline engine (or ICE engine) to be driven on the road. This allows oxygen to be supplied to the catalyst so that it can compensate for the ammonia conversion.
[0012] Preferably, the catalyst control means has an additional control mode, namely an inhibition mode if the catalyst has a charge greater than the third charge threshold, and a temperature lower than the second temperature threshold, in which an inhibitory means inhibits the production of ammonia at engine start-up.
[0013] This makes it possible to limit the amount of ammonia produced by the catalysts, and consequently the phenomenon of ammonia leakage.
[0014] Preferably, the charge estimation means is based on a physical model of the equilibrium between an absorption and a desorption of ammonia from the catalyst, as well as on redox reactions of ammonia and nitrogen oxides.
[0015] This allows for a precise determination of the quantity of ammonia in the catalyst.
[0016] The invention further relates to a method of controlling a catalyst of a motor vehicle according to the invention, characterized in that it comprises the following steps: - a step without a control strategy if the catalyst has a charge below a first charge threshold; or if the catalyst has a charge above the first charge threshold and below a second charge threshold, and has a temperature below a first temperature threshold; - a heating stage if the catalyst has a charge greater than the second charge threshold and less than a third charge threshold, and a temperature lower than the first temperature threshold; or if the catalyst has a charge greater than the third charge threshold, and a temperature lower than the first temperature threshold, and greater than a second temperature threshold, in which a request for heating of the catalyst is made as a function of a given torque application.
[0017] Preferably, during the heating stage, the catalyst temperature is increased to a value between 250°C and 450°C, and for a given catalyst heating demand, a minimum torque demand is calculated as a function of: - engine speed; - engine coolant temperature; - a temperature upstream of the catalyst; - the ammonia charge of the catalyst.
[0018] Preferably, the control method further comprises the following steps: - an opportunistic purging step if the catalyst has a charge higher than the first charge threshold and lower than the second charge threshold, and has a temperature higher than the first temperature threshold, in which the motor is coupled to the wheels and a demand - engine running on the road if the accelerator control is released; - an active running and purging stage if the catalytic converter has a load exceeding the second load threshold, and a temperature exceeding the first temperature threshold, in which the engine is coupled to the wheels with an injection cut-off.
[0019] Preferably, the control method further includes an inhibition step if the catalyst has a charge greater than the third charge threshold, and a temperature lower than the second temperature threshold, in which the production of ammonia is inhibited when the engine is started.
[0020] Preferably, the charge estimation step is based on a physical model of the equilibrium between an absorption and a desorption of ammonia from the catalyst, as well as on redox reactions of ammonia and nitrogen oxides.
[0021] Another object of the invention relates to a computer program comprising program code instructions for executing the steps of the control method according to the invention, when said program is running on a computer.
[0022] The invention will be further detailed by the description of non-limiting embodiments, and on the basis of the attached [Fig.1] illustrating the different control strategies as a function of temperature and catalyst load within the framework of the invention.
[0023] The ammonia leakage catalyst is a passive component of the exhaust system, located at the end of the exhaust system, after the catalytic converters, and before the exhaust silencer. The storage and conversion of ammonia by the catalyst can be managed with a specific powertrain management strategy for the internal combustion engine and its coupling to the wheels.
[0024] The strategy is based on 5 different modes, which will be described below, and the demand for a specific mode is based on the estimation of the catalyst temperature, the estimation of the catalyst ammonia load, and the catalyst history, i.e., whether the load is increasing or decreasing. The estimation of the current ammonia storage is based on a physical equilibrium model between ammonia adsorption / desorption and the NOx / NH3 redox reactions.
[0025] This allows us to determine 5 different modes of action: - Normal mode 0: In this mode, no strategy is required; - the mode of opportunistic purge levers 1: for example a drive request (or "dragging" in English) is made if possible: the motor is coupled to the wheels, and an opportunistic drive is implemented when the foot is released; - Heating mode 2: a heating request for the leaky catalyst ammonia can be applied with minimal torque; - Active drive and purge mode 3: In this mode, the engine is coupled to the wheels with an injection cut-off; - Inhibition mode 4: This is a protection mode to prevent the production of ammonia when restarting the engine in the event that the catalyst is almost full, but not hot enough for the ammonia to be converted.
[0026] The normal mode 0 is determined if the catalyst has a low charge below a first charge threshold A; or if the catalyst has a charge above the first charge threshold A and below a second charge threshold B, and has a temperature below a first temperature threshold Tl.
[0027] The opportunistic lever mode 1 is determined if the catalyst has a charge greater than the first charge threshold A and less than a second charge threshold B, and has a temperature greater than the first temperature threshold TL
[0028] Heating mode 2 is determined if the catalyst has a charge greater than the second charge threshold B and less than a third charge threshold Bl, and has a temperature less than the first temperature threshold Tl; or if the catalyst has a charge greater than the third charge threshold Bl, and has a temperature less than the first temperature threshold Tl, and greater than a second temperature threshold T2.
[0029] The active drive and purge mode 3 is determined if the catalyst has a load greater than the second load threshold B, and has a temperature greater than the temperature threshold T.
[0030] Inhibition mode 4 is determined if the catalyst has a charge greater than the third charge threshold Bl, and has a temperature less than the second temperature threshold T2.
[0031] Heating the catalyst aims to increase its internal temperature to a value above 250°C so that it can convert the stored ammonia in the presence of oxygen. For a given catalyst heating demand, a minimum torque demand is calculated based on: - Engine speed; - The engine coolant temperature; - The temperature upstream of the catalyst; - The ammonia charge of the catalyst.
[0032] The dragging process aims to supply oxygen to the catalyst so that it can complete the ammonia conversion, as the catalyst is already hot enough to do so. Dragging is a mode in which the internal combustion engine is coupled to the wheels, with fuel injection cut-off so that oxygen can be supplied to the exhaust line in large quantities and at a high mass flow rate. Furthermore, it supplies oxygen to a catalyst that is already Hot avoids the event of massive release of ammonia from the catalyst which occurs when the catalyst temperature rises too high.
[0033] The protection method aims to limit the amount of ammonia produced by the catalysts, to ensure that a catalyst which is already almost full and not hot enough to accommodate the conversion of ammonia would not be further charged, thus avoiding ammonia leakage events (massive amount of ammonia seen at the outlet of the catalyst as a consequence of the catalyst's inability to charge more ammonia.
[0034] The invention further relates to a program for implementing a method as described above. The program can be loaded into the memory of a motor vehicle controller, for example, an exhaust system controller.
Claims
Demands
1. A motor vehicle comprising an engine; wheels; an engine throttle control; an exhaust line equipped with an ammonia leakage catalyst; a temperature estimation means estimating the temperature (T) of the catalyst; a load estimation means estimating the ammonia load (Q) of the catalyst; a history estimation means estimating whether the ammonia load (Q) is increasing or decreasing; and a catalyst control means based on control modes among: - a mode with no control strategy (0) if the catalyst has a load (Q) below a first load threshold (A); or if the catalyst has a load (Q) above the first load threshold (A) and below a second load threshold (B), and has a temperature (T) below a first temperature threshold (T1);- a heating method (2) if the catalyst has a charge (Q) greater than the second charge threshold (B) and less than a third charge threshold (Bl), and has a temperature (T) less than the first temperature threshold (Tl); or if the catalyst has a charge (Q) greater than the third charge threshold (Bl), and has a temperature (T) less than the first temperature threshold (Tl), and greater than a second temperature threshold (T2), in which a heating means makes a heating demand on the catalyst as a function of a given torque application.
2. Motor vehicle according to claim 1, characterized in that the heating means increases the temperature of the catalyst to a value between 250°C and 450°C, and in that for a heating demand of the catalyst, a minimum torque demand is calculated as a function of: - an engine speed; - an engine coolant temperature; - a temperature upstream of the catalyst; - the ammonia charge of the catalyst.
3. A motor vehicle according to any one of claims 1 to 2, characterized in that the catalyst control means has additional control modes, namely: - an opportunistic purging mode (1) if the catalyst has a charge (Q) greater than the first charge threshold (A) and less than the second threshold of load (B), and has a temperature (T) above the first temperature threshold (Tl), in which an opportunistic purge means performs engine-to-wheel coupling and drive demand if the throttle control is released; - an active drive and purge mode (3) if the catalyst has a load (Q) above the second load threshold (B), and has a temperature (T) above the first temperature threshold (Tl), in which a drive means performs engine-to-wheel coupling with injection cut-off.
4. Motor vehicle according to any one of claims 1 to 3, characterized in that the catalyst control means has an additional control mode, namely an inhibition mode (4) if the catalyst has a charge above the third charge threshold (Bl), and has a temperature below the second temperature threshold (T2), in which an inhibition means inhibits the production of ammonia at engine start-up.
5. Motor vehicle according to any one of claims 1 to 4, characterized in that the load estimation means is based on a physical model of the equilibrium between an absorption and a desorption of ammonia from the catalyst, as well as on redox reactions of ammonia and nitrogen oxides.
6. A method for controlling a catalyst of a motor vehicle according to any one of claims 1 to 5, characterized in that it comprises the following steps: - a step without a control strategy (0) if the catalyst has a charge (Q) less than a first charge threshold (A); or if the catalyst has a charge (Q) greater than the first charge threshold (A) and less than a second charge threshold (B), and has a temperature (T) less than a first temperature threshold (Tl); - a heating step (2) if the catalyst has a charge (Q) greater than the second charge threshold (B) and less than a third charge threshold (Bl), and has a temperature (T) less than the first temperature threshold (Tl);or if the catalyst has a charge (Q) greater than the third charge threshold (Bl), and has a temperature (T) less than the first temperature threshold (Tl), and greater than a second temperature threshold (T2), in which a heating demand is made for the catalyst; function of a given application of torque.
7. A control method according to claim 6, characterized in that in the heating step, the temperature of the catalyst is increased to a value between 250°C and 450°C, and for a heating demand of the catalyst, a minimum torque demand is calculated as a function of: - an engine speed; - an engine coolant temperature; - a temperature upstream of the catalyst; - the ammonia charge of the catalyst.
8. A control method according to any one of claims 6 to 7, characterized in that it further comprises the following steps: - an opportunistic purging step if the catalyst has a load (Q) greater than the first load threshold (A) and less than the second load threshold (B), and has a temperature (T) greater than the first temperature threshold (Tl), in which engine coupling to the wheels and a request for engine drive on the road is made if the acceleration control is released; - an active drive and purging step if the catalyst has a load (Q) greater than the second load threshold (B), and has a temperature (T) greater than the first temperature threshold (Tl), in which engine coupling to the wheels is made with an injection cut-off.
9. A control method according to any one of claims 6 to 8, characterized in that it further comprises an inhibition step (4) if the catalyst has a charge above the third charge threshold (Bl), and has a temperature below the second temperature threshold (T2), in which the production of ammonia is inhibited at engine start-up.
10. Computer program comprising program code instructions for performing the steps of the control process according to any one of claims 6 to 9, when said program is running on a computer.