Method for diagnosing a valve in an air supply circuit of a motor vehicle passenger compartment

Abstract

The invention relates to a method for diagnosing a valve (6) of an air supply circuit (1) for a passenger compartment (3) of a motor vehicle capable of changing state between a closed state and an open state. The method comprises a step of comparing a first state value EtatN-1 of the valve taken at a time tN-1 and a second state value Etat0 of the valve taken at a time t0 and a step of comparing a first variable TintN-1 measured at time tN-1 by an internal measuring device (2b) positioned in the air supply circuit and a second variable Tint0 measured at time t0 by the internal measuring device, if the first state value EtatN-1 is different from the second state value Etat0, in order to detect a malfunction of the valve. Abstract figure: Fig. 1

Description

Title of the invention: Method for diagnosing a valve in an air supply circuit of a motor vehicle passenger compartment

[0001] The invention relates to a method for diagnosing an intake valve in an air supply circuit of a motor vehicle passenger compartment.

[0002] A motor vehicle conventionally comprises a passenger compartment supplied with air via an air supply circuit.

[0003] The supply circuit comprises an aerator, through which air from outside the motor vehicle is admitted and a first air intake duct, called an "external air inlet duct", which connects the aerator to an air pulsation fan, diffusing the air into the passenger compartment.

[0004] The exterior air intake duct further comprises a filter (or several filters, depending on the level of finish of the motor vehicle), through which the admitted air passes in order to be purified.

[0005] The filtered air is conveyed through the outside air intake duct to the air pulsation fan, which draws in the filtered air and diffuses it into the passenger compartment.

[0006] The supply circuit further comprises a second air intake duct, called the “passenger compartment duct”, forming a loop between the passenger compartment of the motor vehicle and the exterior air intake duct.

[0007] The outside air inlet duct comprises an internal measuring device positioned downstream of the filters and which is responsible for carrying out measurements representative of the quality of the filtered air passing through the outside air inlet duct.

[0008] The air supply circuit comprises a valve, generally called an air intake valve, positioned in the outside air supply duct and connecting the interior to the exterior of the passenger compartment. The valve is intended to activate between a closed state in which the outside air supply duct is closed and an open state in which the outside air supply duct is open.

[0009] The valve comprises an air intake flap connected to a computer which can be partially opened in order to connect the second air intake duct to the outside air supply duct to allow outside air and air from the passenger compartment to pass through. The air intake flap can be completely opened to close the second air intake duct and allow only outside air to enter through the outside air supply duct.

[0010] Patent FR3051146B1 describes, for example, a system which controls the air intake and air recirculation flap as a function of the air pollution parameters outside and inside the passenger compartment.

[0011] In certain cases, a vehicle user may request closure of the air intake valve to cross a polluted tunnel, for example. The passenger compartment computer then receives information from the air intake valve indicating that the valve is indeed in the “closed” state and considers that the situation is normal and consistent with the user's request.

[0012] However, if the valve is defective, the flap may remain open or partially open without the computer detecting this state. Thus, the user crosses the tunnel with the air intake valve in the "open" or "partially open" position without knowing it.

[0013] There is no system in the prior art for analyzing failure of the operation of the intake flap.

[0014] The aim of the invention is therefore to overcome the drawbacks of the prior art by proposing a method for diagnosing a valve of an air supply circuit of a motor vehicle passenger compartment making it possible to detect a malfunction of the valve.

[0015] To this end, the invention thus relates, in its broadest sense, to a method for diagnosing a valve of an air supply circuit of a motor vehicle passenger compartment positioned in an exterior air supply duct connecting the interior to the exterior of the passenger compartment. The valve is capable of changing state between a closed state in which the exterior air supply duct is closed and an open state in which the exterior air supply duct is open. The exterior air supply duct comprises at least one internal measuring device positioned downstream of the valve and intended to measure a variable Tint representative of the quality of the air passing through the exterior air supply duct.

[0016] According to the invention, the method comprises: • A first step of recording the state of the valve at a time tN-1, providing a first value of the state of the valve StateN-1, • A second step of recording the state of the valve at a time tO, providing a second value of the state of the valve EtatO, • A third step of measuring a first variable TintN-1 by the internal measuring device at time tN-1, • A fourth step of measuring a second variable TintO by the internal measuring device at time tO, • A fifth step of comparison between the first state value EtatN-1 and the second state value EtatO of the valve, and • A sixth step of comparison between the first measured variable TintN-1 and the second measured variable TintO, if the first state value EtatN-1 is different from the second state value EtatO, in order to detect a valve malfunction.

[0017] The invention thus provides a method for diagnosing a valve of an air supply circuit of a motor vehicle passenger compartment making it possible to detect a malfunction of the valve.

[0018] The invention makes it possible to check that the passenger compartment air intake valve is functioning correctly and that the information on its opening and closing status is correct.

[0019] It is possible to monitor the opening or closing control of the passenger compartment air intake valve by means of the internal measuring device comprising air quality sensors.

[0020] It is possible to check that the change in state of the valve is in accordance with the opening or closing command given by the user or the computer.

[0021] It is thus possible to know the state of the valve with certainty and to memorize any malfunction in a computer memory so that the repair of the valve can be taken care of as quickly as possible.

[0022] According to a variant, when the first state value of the valve EtatN-1 is equal to the open state and the second state value of the valve EtatO is equal to the closed state, a malfunction of the valve is detected when the first measured variable TintN-1 is less than or equal to the second measured variable TintO.

[0023] This solution allows to control the operation of the valve using the already existing internal measuring device, without additional elements, which does not increase manufacturing costs and provides a simple solution.

[0024] According to a variant, when the first state value of the valve EtatN-1 is equal to the closed state and the second state value of the valve EtatO is equal to the open state, a malfunction of the valve is detected when the first measured variable TintN-1 is greater than or equal to the second measured variable TintO.

[0025] This solution allows to control the operation of the valve using the already existing internal measuring device, without additional elements, which does not increase manufacturing costs and provides a simple solution.

[0026] According to a variant, the first variable TintN-1 and the second variable TintO are particle rates or carbon monoxide (CO) rates or sulfur dioxide (SO2) rates or ozone (03) rates or nitrogen dioxide (NO2) rates.

[0027] According to a variant, third and fourth steps are carried out during a first measurement series to obtain as first variable an ozone rate TintO3N-1 and as second variable an ozone rate TintO30. The first variable TintO3N-1 is compared to the second variable TintO30 during a sixth step of the first measurement series. Third and fourth steps are carried out during a second measurement series to obtain as first variable an ozone rate TintO3N-1 and as second variable an ozone rate TintO30. sulfur dioxide TintSO2N-l and as a second variable a sulfur dioxide rate TintSO20. The first variable TintSO2N-l is compared to the second variable TintSO20 in a sixth step of the second measurement series.

[0028] It is preferable to measure only the ozone levels and the sulfur dioxide levels to take into account that the vehicle occupant may smoke, thus generating carbon monoxide (CO), nitrogen dioxide (NO2) and particles which distort the measurements.

[0029] According to a variant, the vehicle comprises openings and opening windows in the closed position during the third and fourth measurement steps.

[0030] This ensures the reliability of the diagnosis.

[0031] According to one variant, the state of the valve is recorded at time intervals of between 500 milliseconds and 1 second.

[0032] This interval allows rapid detection of valve failure.

[0033] According to a variant, a first fault code is generated when a malfunction of the valve is detected during the transition from the open state to the closed state. A second fault code, different from the first fault code, is generated when a malfunction of the valve is detected during the transition from the closed state to the open state, the fault codes being stored in a memory of a computer.

[0034] This provides clarification on the type of problem encountered on the valve, namely whether the fault comes from the opening or closing of the valve.

[0035] The diagnostic method makes it possible to diagnose a fault in the cabin air intake valve and therefore to warn users quickly. When the vehicle arrives at the after-sales service, the after-sales team accesses the fault code directly indicating the type of fault in the cabin air intake valve without wasting time searching for the fault. This saves time and money.

[0036] According to a variant, the fault codes change from the “permanent fault” state to the “transient fault” state if the fault code is generated only once.

[0037] This makes it possible to take into account measurement artifacts and not to change the valve unnecessarily.

[0038] The invention also relates to a vehicle implementing the diagnostic method as defined above. The internal measuring device and the valve are connected to a computer of the vehicle.

[0039] An embodiment of the present invention will be described below, by way of non-limiting examples, with reference to the single appended figure in which:

[0040] [Fig. 1] schematically illustrates an air supply circuit for a motor vehicle passenger compartment.

[0041] In the remainder of the description, elements having an identical structure or analogous functions are designated by the same reference.

[0042] [Fig.l] illustrates an air supply circuit 1 for a passenger compartment 3 of a motor vehicle.

[0043] The supply circuit 1 comprises an aerator, for example, positioned in the upper part of the passenger compartment 3, in particular at the level of the awning of the motor vehicle.

[0044] The supply circuit 1 comprises an outside air supply duct 4, called an “outside air inlet duct”, which connects the aerator to an air pulsation fan 7, diffusing the air into the passenger compartment 3.

[0045] The outside air supply duct 4 comprises a filtration device 5 comprising at least one filter, for example, chosen from the group containing: a pollen filter, an activated carbon filter, an anti-allergen filter, a particle filter.

[0046] Depending on the level of finish, equipment or options of the motor vehicle, the motor vehicle includes one or more of the filters listed in the aforementioned group.

[0047] More generally, the filter designates equipment designed to filter, in the air which feeds it, at least one chemical species in solid form, for example fine particles or dust, or in gaseous form, comprising for example carbon monoxide (CO), sulfur dioxide (SO2), ozone (03), nitrogen dioxide (NO2), carbon dioxide (CO2), oxygen (02).

[0048] The filter may also include, as a supplement or alternative, a function for dehumidifying the air passing through it.

[0049] The filtered air is conveyed through the outside air supply duct 4 to the air pulsation fan 7, designed to suck in the filtered air and distribute it into the passenger compartment 3.

[0050] The supply circuit 1 further comprises a passenger compartment duct 8, forming a loop between the passenger compartment 3 of the motor vehicle and the exterior air supply duct 4 for recycling the air from the passenger compartment 3.

[0051] In the exemplary embodiment of the supply circuit 1 illustrated in [Fig.l], the passenger compartment duct 8 comprises a filtration assembly 9 designed to filter the air circulating from the passenger compartment 3 to the outside air supply duct 4.

[0052] For example, the filtration assembly 9 comprises a small filter which has the function of cleaning the air coming from the passenger compartment 3.

[0053] According to an alternative embodiment not shown, the passenger compartment duct 8 does not include any filtration assembly 9.

[0054] The outside air supply duct 4 comprises a valve 6 for controlling the air flow, for example a three-way valve, called a “Y valve”, designed and arranged for: Close the passenger compartment duct 8 so that all the air entering the motor vehicle is admitted via the outside air supply duct 4, or • Close the outside air supply duct 4 to prevent outside air from entering the passenger compartment 3, for example when the user of the motor vehicle operates the supply circuit in “recycling” mode, for example when the motor vehicle passes through a polluted tunnel, or • Admit into the outside air supply duct 4 air from both outside the motor vehicle and air from the passenger compartment 3 in order to allow partial renewal of the air and to begin to bring the air from outside the motor vehicle to the temperature of the passenger compartment 3.

[0055] In the embodiment illustrated in [Fig.l], the air flow control valve 6 is mounted downstream of the filtration device 5, the upstream and downstream being understood relative to the direction of air flow in the supply circuit 1, i.e. from the outside to the inside of the passenger compartment 3.

[0056] The valve 6 is capable of changing state between a closed state in which the outside air supply duct 4 is closed and an open state in which the outside air supply duct 4 is at least partially open.

[0057] The valve 6 comprises an air intake flap connected to a computer which can be partially opened in order to connect the passenger compartment duct 8 to the outside air supply duct 4 to allow outside air and air from the passenger compartment 3 to pass through. The air intake flap can be completely opened to close the passenger compartment duct 8 and allow only outside air to enter through the outside air supply duct 4.

[0058] The supply circuit 1 comprises an external measuring device 2a intended to measure a variable representative of the quality of the outside air entering the outside air supply duct 4 of the passenger compartment 3 of the motor vehicle. The external measuring device 2a is mounted in the outside air supply duct 4, upstream of the valve 6, that is to say between the valve 6 and the air pulsation fan 7.

[0059] The external measuring device 2a may comprise a particle rate sensor measuring particle sizes contained in the air flow passing through the external air supply duct 4.

[0060] The particle rate sensor is an optical sensor designed to measure the content of particles less than 2.5 pm or less than 10 pm contained in the air passing through it.

[0061] In this regard, the particle rate sensor is also called a “PM2.5” sensor or a “PM 10” sensor.

[0062] The operating principle is as follows: air passes through a housing containing an infrared light emitter and the particle rate sensor measures the content of these particles contained in the air by measuring the quantity of light reflected by the particles. The wavelength of the light source makes it possible to distinguish the particle sizes, this distinction being materialized on the pulse pattern of the output voltage of the optical sensor, which makes it possible to distinguish between the particles.

[0063] The external measuring device 2a may also comprise a sensor measuring the ozone (03) level and / or a sensor measuring the nitrogen dioxide (NO2) level and / or a sensor measuring the sulfur dioxide (SO2) level and / or a sensor measuring the carbon monoxide (CO) level in the air flow passing through the outside air supply duct 4, for example.

[0064] The external measuring device 2a may be an air quality control system, known as “AQS”, an acronym for “Air Quality System”.

[0065] The air quality monitoring system is capable of measuring the levels of carbon monoxide (CO), sulfur dioxide (SO2), ozone (03), and nitrogen dioxide (NO2) at the same time.

[0066] The supply circuit 1 also comprises an internal measuring device 2b intended to measure a variable Tint representative of the quality of the air passing through the exterior air supply duct 4 of the passenger compartment 3, i.e. the air filtered by the filtration device 5. The internal measuring device 2b is mounted in the exterior air supply duct 4, downstream of the filtration device 5.

[0067] The passenger compartment duct 8 opens upstream of the internal measuring device 2b and can be closed by the flap of the valve 6.

[0068] Thus, the air passing through the external measuring device 2a is not filtered by the filtration device 5 whereas the air passing through the internal measuring device 2b is filtered by the filtration device 5.

[0069] As for the external measuring device 2a, the internal measuring device 2b comprises a particle rate sensor measuring particle sizes contained in the air flow passing through the outside air supply duct 4 and / or a sensor measuring the ozone (03) rate and / or a sensor measuring the nitrogen dioxide (NO2) rate and / or a sensor measuring the sulfur dioxide (SO2) rate and / or a sensor measuring the carbon monoxide (CO) rate in the air flow passing through the outside air supply duct 4, for example.

[0070] These sensors have been previously described.

[0071] The internal measuring device 2b may comprise an air quality control system, known as “AQS”, an acronym for “Air

[0072]

[0073]

[0074]

[0075]

[0076]

[0077]

[0078]

[0079]

[0080] Quality System”. The air quality monitoring system is capable of measuring carbon monoxide (CO), sulfur dioxide (SO2), ozone (03), and nitrogen dioxide (NO2) levels at the same time. The external and internal measuring devices 2a, 2b are identical and measure the same type of variable representative of air quality. If the external measuring device 2a measures particle rates of 2.5 p and 10 p, then the internal measuring device 2b also measures particle rates of 2.5 p and 10 p, for example. The invention relates to a method for diagnosing valve 6 of the supply circuit. The diagnostic process is implemented by hardware and software means integrated into the motor vehicle. For this purpose, the software means include in particular the algorithm implemented to execute the method of the invention. The software resources are, for example, integrated into a motor vehicle computer, for example in the electronic management box known as “BSI”, an acronym for “Intelligent Servitude Box”. The diagnostic process includes: - A first step of recording the state of valve 6 at a time tN-1, providing a first state value StateN-1, - A second step of recording the state of valve 6 at a time t0, providing a second state value Etat0, - A third step of measuring a first variable TintN-1 by the internal measuring device 2b at time tN-1, - A fourth step of measuring a second variable TintO by the internal measuring device 2b at time tO, - A fifth step of comparison between the first state value EtatN-1 and the second state value EtatO of valve 6, and - A sixth step of comparison between the first variable TintN-1 and the second variable TintO, if the first state value EtatN-1 is different from the second state value EtatO, in order to detect a malfunction of the valve 6. Preferably, the second variable TintO is obtained during the last measurement made and the first variable TintN-1 is obtained during the penultimate measurement made. The vehicle has openings including windows. The openings and windows are closed during the third and fourth measurement steps. The calculator must receive information that the openings and windows are closed, otherwise these steps are not carried out.

[0081] If the first state value EtatN-1 is identical to the second state value EtatO, the computer does not compare the first variable TintN-1 to the second variable TintO. A comparison is made only when the computer receives a change of state and orders this change to the valve 6.

[0082] For example, if the first state value StateN-1 and the second state value StateO are equal to the closed state, the comparison of the measurements is not carried out.

[0083] The state of valve 6 is recorded by the computer at time intervals between 500 milliseconds and 1 second.

[0084] According to a first embodiment, the valve 6 is initially open, the first state value StateN-1 being equal to the open state, then the valve 6 is closed, the second state value StateO being equal to the closed state.

[0085] When the valve 6 is open, the internal measuring device 2b detects pollutants coming from outside. When the valve 6 is closed, the flap of the valve 6 completely closes the outside air supply duct 4, the outside air can no longer pass through the outside air supply duct 4. The passenger compartment duct 8 then communicates with a portion of the outside air supply duct 4. The internal measuring device 2b is only in contact with the air coming from the passenger compartment 3 and is supposed to detect less pollutant.

[0086] The computer detects a change in the state of the valve and authorizes the sixth step of comparison between the first variable TintN-1 and the second variable TintO.

[0087] A malfunction of the valve 6 is detected when the first measured variable TintN-1 is less than or equal to the second measured variable TintO.

[0088] Normal operation of the valve 6 is confirmed when the first measured variable TintN-1 is greater than or equal to the second measured variable TintO.

[0089] According to a second embodiment, the valve 6 is initially closed, the first state value StateN-1 being equal to the closed state, then the valve 6 is open, the second state value StateO being equal to the open state.

[0090] The computer detects a change in the state of the valve and authorizes the sixth step of comparison between the first variable TintN-1 and the second variable TintO.

[0091] A malfunction of the valve 6 is detected when the first measured variable TintN-1 is greater than or equal to the second measured variable TintO.

[0092] Normal operation of the valve 6 is confirmed when the first measured variable TintN-1 is less than or equal to the second measured variable TintO.

[0093] The first variable TintN-1 and the second variable TintO are particle rates of 2.5 p and 10 p or carbon monoxide (CO) rates or sulfur dioxide (SO2) rates or ozone (03) rates or nitrogen dioxide (NO2) rates.

[0094] According to one embodiment, the 2.5 p and 10 p particle levels, the carbon monoxide (CO) levels, the sulfur dioxide (SO2) levels, the ozone (03) levels and the nitrogen dioxide (NO2) levels are measured simultaneously and recorded by the computer so as to obtain several first variables TintN-1 and several second variables TinO each associated with a pollutant.

[0095] The third, fourth and sixth steps are carried out for each pollutant.

[0096] It is preferable to measure only ozone levels and sulfur dioxide levels to take into account that the vehicle occupant may smoke, thus generating carbon monoxide (CO), nitrogen dioxide (NO2) and particles which distort the measurements.

[0097] The internal measuring device 2b comprises a sensor measuring the ozone level and a sensor measuring the sulfur dioxide level. The ozone and sulfur dioxide levels are measured simultaneously during the third and fourth measurement steps.

[0098] For example, the third and fourth steps are carried out during a first series of measurements to obtain as first variable an ozone rate TintO3N-1 and as second variable an ozone rate TintO30.

[0099] The first variable TintO3N-l is compared to the second variable TintO30 during the sixth step of this first series of measurements.

[0100] The third and fourth steps are carried out during a second series of measurements to obtain as a first variable a sulfur dioxide rate TintSO2N-1 and as a second variable a sulfur dioxide rate TintSO20.

[0101] The first variable TintSO2N-l is compared to the second variable TintSO20 during a sixth step of this second series of measurements.

[0102] The two series of measurements are preferably carried out simultaneously.

[0103] More than two measurement series are possible depending on the number of additional pollutants to be measured, such as particles or carbon monoxide (CO) or nitrogen dioxide (NO2).

[0104] An example of operation is given below.

[0105] The vehicle's openings and windows are all closed and valve 6 is open.

[0106] In this example, valve 6 is initially open, the first state value StateN-1 being equal to the open state, then valve 6 is closed, the second state value StateO being equal to the closed state.

[0107] The computer detects a change in state of the valve during the fifth step of comparison between the first state value EtatN-1 and the second state value EtatO of the valve 6 and authorizes the sixth step of comparison between the first variable TintN-1 and the second variable TintO.

[0108] A first ozone rate TintO3N-1 is previously obtained during a third measurement step when the valve 6 is open and a second ozone rate TintO30 is also previously obtained during a fourth measurement step when valve 6 is closed.

[0109] At the same time, a first rate of sulfur dioxide TintSO2N-1 is previously obtained during a second third measurement step when the valve 6 is open and a second rate of sulfur dioxide TintSO20 is also previously obtained during a second fourth measurement step when the valve 6 is closed.

[0110] If the first ozone rate TintO3N-1 is higher than the second ozone rate TintO30, the computer considers the situation normal and that the valve 6 is working correctly.

[0111] If the first ozone rate TintO3N-1 is less than or equal to the second ozone rate TintO30, the computer considers the situation abnormal and that the valve 6 is malfunctioning.

[0112] Similarly, if the first sulfur dioxide rate TintSO2N-1 is less than or equal to the second sulfur dioxide rate TintSO20, the computer considers the situation abnormal and that the valve 6 is malfunctioning.

[0113] The computer triggers a type 1 configuration and a first fault code is recorded in the computer memory if at least one of the previous abnormal situations is detected.

[0114] In the case where valve 6 was initially closed then opened, and the computer considered that valve 6 was malfunctioning, it would trigger a type 2 configuration and a second fault code, different from the first fault code, would be recorded in the computer's memory.

[0115] Alternatively, the computer can display a message on the dashboard or light up a warning light to indicate the need to have the behavior of the valve 6 checked when a fault code is recorded.

[0116] When the vehicle arrives at the after-sales service following this illumination of the warning light or for a simple service, for example, the after-sales service team looks at the fault codes. If the after-sales service finds one of the two fault codes indicating a malfunction of the passenger compartment air intake valve 6, it proceeds to check the behavior of this valve 6 or to replace it.

[0117] Fault codes can only be cleared by after-sales service.

[0118] However, if during subsequent runs, no malfunction of the valve 6 is detected, the fault code(s) change from the “permanent fault” state to the “transient fault” state.

[0119] In other words, the fault codes change from the “permanent fault” state to the “transient fault” state if the fault code is generated only once.

[0120] In the “transient fault” state, the after-sales service team is not required to change valve 6 but at least to test its operation.

[0121] If the fault goes into a “transient state”, in the variant of a warning light or a message on the dashboard, the warning light and / or the message are inhibited.

Claims

Claims

1. Method for diagnosing a valve (6) of an air supply circuit (1) for a passenger compartment (3) of a motor vehicle positioned in an exterior air supply duct (4) connecting the interior to the exterior of the passenger compartment (3), the valve (6) being capable of changing state between a closed state in which the exterior air supply duct (4) is closed and an open state in which the exterior air supply duct (4) is open, the exterior air supply duct (4) comprising at least one internal measuring device (2b) positioned downstream of the valve (6) and intended to measure a variable Tint representative of the quality of the air passing through the exterior air supply duct (4), characterized in that the method comprises: - a first step of recording the state of the valve (6) at a time tN-1, providing a first state value of the valve (6) StateN-1,- a second step of recording the state of the valve (6) at a time t0, providing a second state value of the valve (6) EtatO, - a third step of measuring a first variable TintN- 1 by the internal measuring device (2b) at time tN-1, - a fourth step of measuring a second variable TintO by the internal measuring device (2b) at time t0, - a fifth step of comparing the first state value EtatN-1 and the second state value EtatO of the valve (6), and - a sixth step of comparing the first measured variable TintN-1 and the second measured variable TintO, if the first state value EtatN-1 is different from the second state value EtatO, in order to detect a malfunction of the valve (6).,

2. Diagnostic method according to claim 1, characterized in that the first state value of the valve (6) EtatN-1 is equal to the open state, the second state value of the valve (6) EtatO being equal to the closed state, a malfunction of the valve (6) is detected when the first measured variable TintN-1 is less than or equal to the second variable TintO measured.

3. Diagnostic method according to claim 1, characterized in that the first state value of the valve (6) EtatN-1 is equal to the closed state, the second state value of the valve (6) EtatO being equal to the open state, a malfunction of the valve (6) is detected when the first measured variable TintN-1 is greater than or equal to the second measured variable TintO.

4. Diagnostic method according to any one of claims 1 to 3, characterized in that the first variable TintN-1 and the second variable TintO are particle levels or carbon monoxide (CO) levels or sulfur dioxide (SO2) levels or ozone (03) levels or nitrogen dioxide (NO2) levels.

5. Diagnostic method according to claim 4, characterized in that third and fourth steps are carried out during a first measurement series to obtain as first variable an ozone level TintO3N-l and as second variable an ozone level TintO30, the first variable TintO3N-l being compared to the second variable TintO30 during a sixth step of the first measurement series, third and fourth steps being carried out during a second measurement series to obtain as first variable a sulfur dioxide level TintS02N-l and as second variable a sulfur dioxide level TintSO20, the first variable TintS02N-l being compared to the second variable TintSO20 during a sixth step of the second measurement series.

6. Diagnostic method according to any one of claims 1 to 5, characterized in that the state of the valve (6) is recorded at time intervals between 500 milliseconds and 1 second.

7. Diagnostic method according to any one of claims 1 to 6, characterized in that a first fault code is generated when a malfunction of the valve (6) is detected during the transition from the open state to the closed state, a second fault code, different from the first fault code, being generated when a malfunction of the valve (6) is detected during the transition from the closed state to the open state, the fault codes being stored in a memory of a computer.

8. Diagnostic method according to claim 7, characterized in that the fault codes change from the “permanent fault” state to the “transient fault” state if the fault code is generated only once.

9. Vehicle, characterized in that it implements the diagnostic method as defined according to any one of claims 1 to 8, the internal measuring device (2b) and the valve (6) being connected to a computer of the vehicle.

10. Vehicle according to claim 9, characterized in that it comprises openings and opening windows in the closed position during the third and fourth measurement steps.

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