Device and method for inspecting the operational status of a treatment unit for gaseous emissions from an internal combustion engine exhaust line.

Abstract

A method for checking the operating state of a processing unit (14) for gaseous emissions from an exhaust line (13) in a spark-ignition internal combustion engine (1) for a motor vehicle, comprising a first oxygen sensor (15) of the proportional type located upstream from the catalytic converter (14) and a second oxygen sensor (16) of the binary type located downstream from the catalytic converter (14), wherein during a deceleration phase of the vehicle, the engine is controlled so that the pressure in the intake collector is increased to a value similar to the idling value, and the amount of oxygen (O ) stored in the catalytic converter is measured. decel ) is calculated until the end of deceleration, and the calculated amount of oxygen (O decel When the value of (S1) is greater than the threshold value, an intrusion diagnostic is initiated at a content of about 1.05 to bleed oxygen in the catalytic converter, and the oxygen storage capacity (OSC) of the catalytic converter (14) is calculated between the start of the rich phase and the switch of the downstream oxygen sensor (16) from a lean state to a rich state, and when the calculated value of the oxygen storage capacity (OSC) is greater than the threshold value (S1), the catalytic converter is declared to be in compliance. [Selected figure] Figure 3

Description

[Technical Field]

[0001] The present invention relates to inspecting the operating state of the exhaust line of an automatic vehicle internal combustion engine, and more particularly to detecting the aging of a processing unit, such as a catalytic converter, which is provided with an exhaust line for processing gaseous emissions.

[0002] More specifically, the present invention relates to monitoring the catalytic effect of a unit for purifying the exhaust gases of an internal combustion engine of a controlled ignition type. Such a unit is commonly referred to as a "catalytic converter," "redox catalytic converter," or "three-way catalytic converter." [Background technology]

[0003] Uncontrolled ignition type internal combustion engines (especially those running on gasoline) emit nitrogen oxides, unburned hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NOx). x Automobiles produce exhaust gases containing pollutants such as carbon monoxide (CO) and unburned hydrocarbons (HC), and nitrogen oxides (NO). Before these pollutants are released into the atmosphere, it is necessary to treat them. Automobiles therefore produce exhaust gases containing pollutants such as carbon monoxide (CO) and unburned hydrocarbons (HC), and nitrogen oxides (NO). x A catalytic converter is installed in the engine's exhaust line to process the molecules of ) and convert them into molecules of nitrogen (N2) and carbon dioxide (CO2) under the action of carbon monoxide.

[0004] The gradual thermal aging of such catalytic converters leads to a decrease in the effectiveness of converting unburned hydrocarbons and carbon monoxide to water and carbon dioxide, and to the effectiveness of converting nitrogen oxides to nitrogen atoms and carbon dioxide under the action of carbon monoxide, the decrease being caused in particular by a reduction in the active surface area for processing contaminants within the catalytic converter. This leads to an increase in the ignition (light-off) temperature at which the oxidation reaction begins, and therefore an increase in pollutant emissions. Furthermore, when the catalytic converter is located upstream of the particle filter, the catalytic converter is used to help regenerate the filter, which means that substantial degradation of the converter can lead to a situation where it is impossible to regenerate the particle filter because it becomes impossible to raise the temperature high enough using the exothermicity of the conversion reaction in the catalytic converter.

[0005] Therefore, it is necessary to inspect the correct operation of the catalytic converter. For this purpose, automated vehicles are generally equipped with status inspection devices that can alert the driver to malfunctions.

[0006] In conventional technology, aging, or more generally, the correct operation of the catalytic phase in the exhaust line, is inspected based on the temperature rise generated by the catalytic activity of the unit to be diagnosed, after the catalytic phase is force-excited by a controlled increase in the concentration of the reducing agent upstream of the catalytic converter, caused by the injection of fuel upstream of the catalytic converter.

[0007] By delaying the injection of fuel into the engine cylinders, the temperature at the outlet of the catalytic converter rises during normal operation, but if the catalytic converter is defective, the outlet temperature does not rise.

[0008] Another known method for establishing catalytic converter diagnostics is to use oxygen storage capacity (OSC) as the decision criterion. Once the conditions for proceeding with inspecting the catalytic converter's operating state (engine speed, load, stability, catalytic converter temperature, and water temperature) are met, a disruption signal is applied to the richness signal.

[0009] "Turbidity" means that the setpoint for the air-fuel mixture in the engine is varied compared to normal engine operation, during normal operation, as is known, the richness of the mixture depends on signals from at least one proportional oxygen probe associated with the engine, upstream of the catalytic converter, and a second oxygen probe downstream, for example, of the binary type. During turbulence, a rich pulse with a richness of 1.07 is applied, followed by a lean pulse with a richness of 0.93. Engine adjustment is thereby forced.

[0010] The oxygen storage capacity of the catalytic converter is calculated by taking into account the richness from the upstream proportional probe and the time required for the downstream binary probe to switch to a lean state after the upstream probe has switched from a rich state to a lean state.

[0011] In other words, when all the conditions for engine operation stability are met, the engine computer applies fluctuations at the richness setpoint by imposing an intrusion toward positive richness and an intrusion toward lean mixture for the fuel mixture delivered to the engine combustion chamber. After these setpoint intrusions, the richness measured by the upstream proportional probe also creates fluctuations in the richness signal toward higher richness and then toward less high richness. The richness downstream of the catalytic converter also undergoes fluctuations, with a delay relative to the fluctuations on the upstream probe.

[0012] As long as the downstream probe is of the binary type, it supplies a signal indicating a "rich" or "lean" state for the mixture, and the switching between the two states is indicated by a sharp change in the signal. The total duration of the fluctuation is approximately 6 seconds.

[0013] Such a method is known, for example, from reference FR-A1 3 057 022, which includes five steps for inspecting the operational status of a redox catalytic converter: a first step of verifying that all operating conditions for the engine to proceed with the inspection are met; a second step of applying a high richness pulse to remove oxygen from the catalytic converter; a third step of applying a low richness pulse to store oxygen in the catalytic converter; a fifth step of calculating the oxygen storage capacity of the catalytic converter between the switching of the upstream probe from a rich state to a lean state and the switching of the downstream probe from a rich state to a lean state; and a fifth step of comparing the calculated value of the oxygen storage capacity of the catalytic converter with a detection threshold. If the calculated value of the oxygen storage capacity of the catalytic converter is higher than the detection threshold, the catalytic converter is considered to be functioning correctly.

[0014] However, such methods for inspecting the operating status of the catalytic converter significantly increase the emission of contaminant particles. Furthermore, such methods require conditions of stability at engine speed and load, which limits the occurrence of diagnostics. Finally, such methods affect drivability due to richness interference.

[0015] Japanese Patent Publication No. 2008-175134 proposes a diagnostic method that makes it possible to avoid the aforementioned drawbacks. In particular, in this method, in order to measure the oxygen storage capacity of the catalytic converter during the oxygen storage phase, the catalytic converter is first filled with oxygen rather than first emptying the catalytic converter, and the oxygen storage capacity of the catalytic converter is calculated later during the oxygen purging phase. This method also measures nitrogen oxides NO x To avoid increasing the emission of pollutant particles, we propose using vehicle deceleration to fill the catalytic converter with oxygen. Similarly, this method means that only a small amount of turbulence is generated during pickup after the vehicle deceleration phase.

[0016] However, such a method has the drawback of causing difficulties in filling the catalytic converter with oxygen during deceleration. In particular, when the driver's foot is removed from the throttle pedal, the engine computer cuts off fuel injection and generally restricts the entry of air (and thus oxygen) into the engine so as to increase engine braking. The throttle valve is fully or almost fully closed. SUMMARY OF THE INVENTION

[0017] An object of the present invention is to benefit from vehicle driving phases in which the vehicle decelerates and then accelerates, in particular to calculate the value of the oxygen storage capacity of the catalytic converter, without disturbing the richness by introducing significant changes to the setpoint, in order to improve known diagnostic methods and devices.

[0018] One subject of the present invention is a method for inspecting the operating state of a processing unit for treating gaseous emissions from an exhaust line in an internal combustion engine of a motor vehicle, comprising a first oxygen sensor of the proportional type located upstream of the catalytic converter and a second oxygen sensor of the binary type located downstream of the catalytic converter.

[0019] The method comprises verifying that the vehicle is in a deceleration phase; controlling the engine if the vehicle is in a deceleration phase; increasing the pressure in the intake manifold to a value similar to the idling value, for example up to about 450 mbar; calculating in millimoles the amount of oxygen accumulated in the catalytic converter until the end of deceleration; comparing the calculated value of the amount of oxygen with a threshold value, for example the oxygen storage capacity of a new catalytic converter; introducing disturbances for a richness of about 1.05 so as to remove oxygen from the catalytic converter when the calculated value of the amount of oxygen exceeds the threshold value; The step of calculating the oxygen storage capacity of the catalytic converter between the start of the rich phase and the switching of the downstream oxygen sensor from the lean state to the rich state, calculated in millimoles of oxygen atoms consumed, and The calculated value for the oxygen storage capacity is compared to a threshold value, and when the calculated value of the oxygen storage capacity exceeds the threshold value, the catalytic converter is declared to be problem-free, and the downstream oxygen sensor switches from the lean state to the rich state, and at that moment, when the calculated value for the oxygen storage capacity is below the threshold value, the catalytic converter is declared to have a problem.

[0020] According to one embodiment, during the engine control step, fuel injection is blocked while keeping the throttle valve open. In that case, the vehicle is not equipped with a coasting function known as "sailing idle" or "coasting idle", or rather, the vehicle is in normal deceleration.

[0021] According to another embodiment, when the vehicle is equipped with a coasting function called "sailing idle" or "coasting idle", during the engine control step, this function is suppressed and the engine is not permitted to operate at idle.

[0022] For example, before calculating the amount of oxygen accumulated in the catalytic converter, it is verified that injection has been blocked.

[0023] When the vehicle speed exceeds a threshold speed value, for example 20 km / h, the gearbox gear ratio being used is not zero (i.e., the gear ratio is being used), and the deceleration is below a threshold deceleration value, the vehicle can be considered to be in a deceleration phase.

[0024] Advantageously, before verifying that the vehicle is in a deceleration phase, it is verified that the diagnosis has not yet been performed in the same trip and that the water temperature is below a temperature threshold value.

[0025] A second aspect of the present invention relates to a device for inspecting the operating status of a processing unit that processes gaseous emissions from the exhaust line of an internal combustion engine of an automobile, comprising a proportional first oxygen sensor located upstream of the catalytic converter and a binary second oxygen sensor located downstream of the catalytic converter.

[0026] The device is A module for verifying that the vehicle is in the deceleration phase, A module for controlling the engine when the vehicle is in the deceleration phase, A module to increase the intake manifold pressure to a value similar to the idle value, for example, approximately 450 mbar, A module for calculating the amount of oxygen accumulated in the catalytic converter in millimoles until the end of deceleration, A module for comparing the calculated value of the amount of oxygen with a threshold, for example, the oxygen storage capacity of the new catalytic converter, A module for introducing turbulence to a richness of approximately 1.05, such that when the calculated amount of oxygen exceeds a threshold, oxygen is removed from the catalytic converter. A module for calculating the oxygen storage capacity of a catalytic converter in millimoles of oxygen atoms consumed between the start of the rich phase and the switching of the downstream oxygen sensor from a lean state to a rich state, The system includes a module for comparing a calculated value of oxygen storage capacity with a threshold value. When the calculated value of oxygen storage capacity exceeds the threshold value, the catalytic converter is declared to be functioning correctly. When the downstream oxygen sensor switches from a lean state to a rich state, and at that moment the calculated value of oxygen storage capacity falls below the threshold value, the catalytic converter is declared to be functioning correctly.

[0027] According to one embodiment, the engine control module is configured to shut off fuel injection while simultaneously keeping the throttle valve open. In this case, the vehicle is not equipped with a coasting function called "cruising idle" or "coasting idle," in other words, the vehicle is in a normal deceleration state.

[0028] According to another embodiment, when a vehicle is equipped with a coasting function called "cruising idle" or "coasting idle," the engine control module is configured to suppress this function and prevent the engine from operating at idle.

[0029] Advantageously, the device includes a module for verifying that injection has been cut off upstream of a module for calculating the amount of oxygen accumulated in the catalytic converter.

[0030] Before inspecting the operating status of the catalytic converter, it is necessary to verify that diagnostics have not yet been performed in the same process. For this purpose, this device includes a verification module that verifies that diagnostics have not yet been performed in the same process.

[0031] This device further includes a module for verifying the conditions required to perform the diagnosis, in particular, that the temperature of the catalyst converter is below a temperature threshold.

[0032] For a vehicle to be considered to be in the deceleration phase, the vehicle speed must be higher than a threshold speed, for example, 20 km / h; the gearbox gear ratio being used must not be 0 (i.e., a gear ratio is being used); and the deceleration must be below the threshold deceleration value.

[0033] Further objects, features, and advantages of the present invention are given merely as non-limiting examples and will become apparent from reading the following description, which is made with reference to the accompanying figures. [Brief explanation of the drawing]

[0034] [Figure 1] This figure schematically shows the structure of an internal combustion engine in an automatic vehicle equipped with an exhaust line that has a catalytic converter associated with a diagnostic device according to the present invention. [Figure 2] This diagram shows the diagnostic module in detail. [Figure 3] This figure shows one implementation of the method according to the present invention. [Modes for carrying out the invention]

[0035] Figure 1 schematically shows a typical example of the structure of an internal combustion engine 1 of an automated vehicle with controlled ignition.

[0036] In the example shown, the internal combustion engine 1 is a supercharged type. The internal combustion engine 1 comprises, but is not limited to, four inline cylinders 2, a fresh air intake manifold 3, an exhaust manifold 4, and a turbocharger system 5. Alternatively, the engine could be a naturally aspirated engine.

[0037] Cylinder 2 is supplied with air via an intake manifold 3 or intake collector 3, and the air itself is supplied by a pipe 6 which is given an air filter 7 and a turbocharger 5 that supercharges the air to engine 1.

[0038] The turbocharger 5 essentially comprises a turbine 8 driven by exhaust gases and a compressor 9 mounted on the same shaft as the turbine 8, which compresses air distributed by an air filter 7 to increase the amount of air entering the cylinders 2 of the engine 1. A heat exchanger 10 may be located behind the outlet from the compressor 9, through which a pipe 11 supplies fresh air to the intake manifold 3.

[0039] As shown in the figure, in a non-limiting example, the intake pipe 11 may include an intake valve (not referenced) for adjusting the flow rate of the air stream entering the intake manifold 3.

[0040] As far as the exhaust manifold 4 is concerned, it collects the exhaust gases produced from combustion and discharges them to the outside through the exhaust gas pipe 12 which opens over the turbine 8 of the turbocharger 5, and through the exhaust line 13.

[0041] Alternatively, the exhaust gas pipe 12 may be equipped with a wastegate (not shown) to regulate the power supplied to the turbine 8 by the exhaust gas.

[0042] The exhaust line 13 shown in Figure 1 essentially oxidizes reducing molecules consisting of carbon monoxide (CO) and unburned hydrocarbons (HC), and then uses carbon monoxide to produce nitrogen oxides (NOx). x The system includes an oxidation-reduction catalytic converter 14 for treating nitrogen oxides (NOx) emitted by the engine 1. This catalytic converter 14 is known to those skilled in the art and will not be described further. However, it should be noted that the catalytic converter 14 has a monolithic structure and is impregnated with a catalytic phase, such as a noble metal, and is given channels with a large surface area for contact with the exhaust gas. Alternatively, the monolith used in the configuration of the catalytic converter 14 may be incorporated into or coupled to a particulate filter (not shown) to achieve a coupling between exhaust gas aftertreatment by oxidation of carbon monoxide and aftertreatment of unburned hydrocarbons in particulate aftertreatment. As an alternative to the oxidation catalytic converter 14, some other unit 14 for treating exhaust gas wastewater, in particular nitrogen oxides (NOx) emitted by the engine 1, may be used. x It may be possible to install a nitrogen oxide trap that can reduce ) to harmless molecules of nitrogen (N2) and water (H2O) under the action of hydrocarbons coming from the engine.

[0043] A proportional-type first oxygen sensor 15 is located downstream of the turbine 8 and upstream of the catalytic converter 14. A binary-type second oxygen sensor 16 is located downstream of the catalytic converter 14. The output signals from the oxygen sensors 15 and 16 are processed in the electronic control unit "UCE" or onboard computer 20. These signals contain information regarding the residual oxygen content of the exhaust gas, as well as the instantaneous fuel / air ratio of the air-fuel mixture drawn in by the engine 1. The air / fuel ratio is also called "richness". The electronic control unit 20 also collects other information via connections not shown, such as the temperature of the air in the intake manifold 3 of the engine 1, the temperature of the engine coolant, the flow rate of air entering the intake manifold 3, the engine speed, the vehicle speed, injection parameters, and the outlet temperature of the catalytic converter 14.

[0044] The control unit or onboard computer 20 essentially controls the operation of engine 1, particularly by adjusting its operating parameters, and checks the operation of the catalytic converter 14.

[0045] More specifically, the control unit 20 performs a diagnosis of the operating status of the catalytic converter 14 to detect excessive aging that may result in increased pollutant emissions.

[0046] To check the operating status of the catalytic converter 14, it is necessary to verify that a diagnosis has not yet been performed in the same stroke. For this purpose, the control unit or device 20 for verifying the operating status of the catalytic converter 14, as detailed in Figure 2, includes a verification module 21 that verifies that a diagnosis has not yet been performed in the same stroke.

[0047] The control unit 20 further includes a verification module 22 that verifies the conditions required to perform the diagnosis, in particular, that the temperature of the catalytic converter 14 is below a temperature threshold T1.

[0048] The control unit 20 also includes a verification module 23 that verifies the conditions for vehicle deceleration. For the vehicle to be considered in a deceleration phase, the vehicle speed must be above a threshold speed value, for example 20 km / h, the gearbox ratio in use must not be zero (or, in other words, the ratio must be actually in use), and the deceleration must be below a threshold deceleration value.

[0049] When the conditions for establishing a diagnosis are simultaneously met and, at the same time, when the vehicle is considered to be in a deceleration phase, it is possible to proceed with the engine control steps. The control unit 20 includes, for this purpose, an engine control module 24.

[0050] In cases where the vehicle is equipped with a coasting function known as "navigation idle" or "coasting idle", the engine control module 24 suppresses this function and does not permit the engine to operate at idle.

[0051] In cases where the vehicle is not equipped with such a coasting function or, in other words, when the vehicle is in normal deceleration, the engine control module 24 cuts off the fuel injection while keeping the throttle valve in the open position.

[0052] The control unit 20 also includes a module 25 for increasing the pressure in the intake manifold to a value similar to the idle pressure, for example up to about 450 mbar.

[0053] The control unit 20 includes a module 26 for verifying that the injection has been cut off and a module 27 for calculating the amount of oxygen O decel accumulated in the catalytic converter until the end of deceleration in millimoles according to the following formula. TIFF0007854296000001.tif21170 Here, Q gas is the mass flow rate in the exhaust in kg / h, T O2 is the oxygen content in the air, equal to 0.21, M OThis is 16 mg / millimole of oxygen.

[0054] The control unit 20 controls the amount of oxygen O decel The system includes a comparator 28 that compares the calculated value for the oxygen storage capacity of the new catalytic converter with that value.

[0055] The control module 20 controls the amount of oxygen O decel When the calculated value for is greater than the oxygen storage capacity of the new catalytic converter, a module 29 is provided for applying turbulence to a richness of 1.05 to remove oxygen from the catalytic converter.

[0056] Finally, the control unit 20 includes a module 30 for calculating the oxygen storage capacity OSC of the catalytic converter 14 in millimoles of oxygen atoms consumed between the start of the rich phase and the switching of the downstream probe 16 from a lean state to a rich state, according to the following formula. TIFF0007854296000002.tif18170 Here, R is the richness measured by the upstream probe. Q gas This is the mass flow rate in exhaust gas in kg / h. Az is the N2 / O2 ratio, which is approximately equal to 3.76. M TOT This is the average molar mass of the exhaust gas, which is approximately 30 g / mol. C bar This represents the molecular nitrogen content of the dry gas in the exhaust, and is approximately equal to 0.81.

[0057] The control unit 20 includes a module 31 for comparing the calculated value of the oxygen storage capacity OSC against a threshold S1. When the calculated value of the oxygen storage capacity OSC is greater than the threshold S1, the catalytic converter is declared to be functioning correctly. In all other cases, the calculation is paused when the downstream probe 16 switches from a lean state to a rich state. At that moment, if the calculated value of the oxygen storage capacity OSC falls below the threshold S1, the catalytic converter is declared to be functioning correctly.

[0058] The flowchart shown in Figure 3 illustrates an example of method 40 implemented by the device shown in Figure 2.

[0059] In the first step 41, it is verified that the diagnosis has not yet been performed in the same process, and in step 42, it is verified that all the conditions required to perform the diagnosis are met, in particular that the temperature of the catalytic converter 14 is below the temperature threshold T1.

[0060] Furthermore, in step 43, it is verified whether the vehicle is in the deceleration phase. For a vehicle to be considered in the deceleration phase, the vehicle speed must be higher than a threshold speed value, for example, 20 km / h, the gearbox ratio being used must not be zero, and the deceleration must be below the threshold deceleration value.

[0061] When the conditions for performing the diagnosis are met simultaneously, and at the same time, the vehicle is considered to be in the deceleration phase, it is possible to proceed with step 44, which controls the engine.

[0062] In cases where a vehicle is equipped with a coasting function known as "cruising idle" or "coasting idle," this function is suppressed, and the engine is not permitted to operate at idle.

[0063] In cases where the vehicle is not equipped with such a coasting function, in other words, when the vehicle is decelerating normally, fuel injection is shut off while the throttle valve is kept in the open position.

[0064] In step 45, the pressure in the intake manifold increases to a value similar to the idling pressure, for example, about 450 mbar.

[0065] Next, in step 46, it is verified that the injection has been cut off, and in that case, the amount of oxygen accumulated in the catalytic converter until the end of deceleration is O decel However, in step 47, it is calculated in millimoles according to the following formula. TIFF0007854296000003.tif21170 Here, Q gas This is the mass flow rate in exhaust gas in kg / h. T O2 This is the oxygen content in the air, which is equal to 0.21. M O This is 16 mg / millimole of oxygen.

[0066] Amount of oxygen O decel The calculated value for the above is compared in step 48 with the oxygen storage capacity of the new catalytic converter, and in step 49, the amount of oxygen O decel When the calculated value for is greater than the oxygen storage capacity of the new catalytic converter, a richness of 1.05 turbulence is applied to remove oxygen from the catalytic converter.

[0067] Finally, in step 50, the oxygen storage capacity OSC of the catalytic converter 14 is calculated in millimoles of oxygen atoms consumed between the start of the rich phase and the switching of the downstream probe 16 from the lean state to the rich state, according to the following formula. TIFF0007854296000004.tif16170 Here, R is the richness measured by the upstream probe. Q gas This is the mass flow rate in exhaust gas in kg / h. Az is the N2 / O2 ratio, which is approximately equal to 3.76. M TOT This is the average molar mass of the exhaust gas, which is approximately 30 g / mol. C bar This represents the molecular nitrogen content of the dry gas in the exhaust, and is approximately equal to 0.81.

[0068] The calculated value for the oxygen storage capacity OSC is then compared to a threshold S1 in step 51. If the calculated value for the oxygen storage capacity OSC is greater than the threshold S1, the catalytic converter is declared to be functioning correctly. In all other cases, the calculation is paused when the downstream probe 16 switches from a lean state to a rich state. At that moment, if the calculated value for the oxygen storage capacity OSC is less than the threshold S1, the catalytic converter is declared to be functioning correctly.

[0069] Thanks to the present invention, effective and robust inspection of the operating status of the catalytic converter based on vehicle deceleration can be enjoyed.

[0070] Furthermore, such testing can reduce the impact of diagnostic disruption phases on drivability and pollutant emissions.

Claims

1. A method for inspecting the operating state of a processing unit (14) that processes gaseous emissions from an exhaust line (13) in a controlled ignition internal combustion engine (1) of an automatic vehicle, comprising a proportional first oxygen sensor (15) located upstream of the catalytic converter (14) and a binary second oxygen sensor (16) located downstream of the catalytic converter (14), It was verified that the aforementioned vehicle was in the deceleration phase. When the vehicle is in the deceleration phase, the engine control step is executed. The pressure in the intake manifold is increased to a value similar to the idle value when the throttle valve is closed. The amount of oxygen accumulated in the catalyst converter until the end of deceleration (O ｄｅｃｅｌ ) is calculated, The amount of oxygen (O ｄｅｃｅｌ The calculated value for ) is compared with the threshold value, The amount of oxygen (O ｄｅｃｅｌ When the calculated value for ) exceeds the threshold, the richness is varied relative to a richness of 1.05 in order to remove oxygen from the catalytic converter. The oxygen storage capacity (OSC) of the catalyst converter (14) is calculated between the start of the rich phase and the switching of the downstream oxygen sensor (16) from a lean state to a rich state. The calculated value of the oxygen storage capacity (OSC) is compared to a threshold (S1), and when the calculated value of the oxygen storage capacity (OSC) exceeds the threshold (S1), the catalytic converter is declared to have no problems. Furthermore, when the downstream oxygen sensor (16) switches from the lean state to the rich state, and at that moment the calculated value of the oxygen storage capacity (OSC) falls below the threshold (S1), the catalytic converter is declared to have a problem. When the speed of the vehicle exceeds the threshold speed of 20 km / h, the gear ratio of the gearbox being used is not 0, and the degree of deceleration is greater than the threshold deceleration value, the vehicle is considered to be in the deceleration phase. A method for checking the operating state of a processing unit (14) such that, when the vehicle is equipped with a coasting function, the coasting function is suppressed during the control step of the engine and the engine is not permitted to operate at idle.

2. The method according to claim 1, wherein during the control step of the engine, fuel injection is shut off while the throttle valve remains open.

3. The amount of oxygen (O) accumulated in the catalyst converter ｄｅｃｅｌ The method according to claim 1 or 2, wherein it is verified that the injection has been blocked before calculating the result.

4. The method according to any one of claims 1 to 3, wherein, before verifying that the vehicle is in the deceleration phase, it is verified that the diagnosis has not yet been performed in the same stroke and that the water temperature is below a temperature threshold (T1).

5. A device for inspecting the operating state of a processing unit (14) that processes gaseous emissions from an exhaust line (13) in an internal combustion engine (1) of an automatic vehicle, comprising a proportional first oxygen sensor (15) located upstream of the catalytic converter (14) and a binary second oxygen sensor (16) located downstream of the catalytic converter (14), A module (23) for verifying that the vehicle is in the deceleration phase, A module (24) for controlling the engine when the vehicle is in the deceleration phase, A module (25) for increasing the intake manifold pressure to a value similar to the idle value when the throttle valve is closed, The amount of oxygen accumulated in the catalyst converter until the end of deceleration (O ｄｅｃｅｌ A module (27) for calculating ) and The amount of oxygen (O ｄｅｃｅｌ A module (28) for comparing the calculated value of ) with a threshold, The amount of oxygen (O ｄｅｃｅｌ When the calculated value of ) exceeds the threshold, a module (29) for varying the richness relative to a richness of 1.05 is provided to remove oxygen from the catalytic converter, A module (30) for calculating the oxygen storage capacity (OSC) of the catalytic converter (14) in millimoles of oxygen atoms consumed between the start of the rich phase and the switching of the downstream oxygen sensor (16) from a lean state to a rich state, The system includes a module (31) for comparing the calculated value of the oxygen storage capacity (OSC) with a threshold value (S1), When the calculated value of the oxygen storage capacity (OSC) exceeds the threshold (S1), the catalytic converter is declared to have no problem. Furthermore, when the downstream oxygen sensor (16) switches from the lean state to the rich state, and at that moment the calculated value of the oxygen storage capacity (OSC) falls below the threshold (S1), the catalytic converter is declared to have a problem. When the speed of the vehicle exceeds the threshold speed of 20 km / h, the gear ratio of the gearbox being used is not 0, and the degree of deceleration is greater than the threshold deceleration value, the vehicle is considered to be in the deceleration phase. When the vehicle is equipped with a coasting function, the engine control module (24) includes a device for checking the operating state of a processing unit (14) configured to suppress the coasting function and prevent the engine from operating at idle.

6. The device according to claim 5, wherein the engine control module (24) is configured to shut off fuel injection while simultaneously keeping the throttle valve open.

7. The amount of oxygen accumulated in the catalyst converter (14) (O ｄｅｃｅｌ The device according to claim 5 or 6, further comprising a module (26) for verifying that injection has been blocked upstream of the module (27) for calculating ).

Images