MOTOR VEHICLE AND DIAGNOSTIC PROCEDURE FOR VERIFYING THE OPENING OF THE FLAPS IN THE SECONDARY AIR INJECTION SYSTEM OF AN INTERNAL COMBUSTION ENGINE

Abstract

The invention relates to a device and a method for performing, at the level of a vehicle (1000) internal combustion engine (500) (1000), a diagnostic check of the opening of a flap (5) in a secondary air injection system (3) bypassing the engine (500) and comprising a pump (4), a pressure sensor (7), said flap (5), and a heating grid (2), by comparing the measured values ​​of pump power (4) and sensor pressure (7) with power and pressure templates calculated based on prior calibrations of the pump (4) and sensor (7). Abstract figure: Fig. 1

Description

Title of the invention: MOTOR VEHICLE AND DIAGNOSTIC METHOD FOR CHECKING THE OPENING OF THE ENGINE SECONDARY AIR INJECTION SYSTEM SHUTTER

[0001] The invention relates to a motor vehicle comprising a heat engine comprising a catalyst on its exhaust circuit, a control unit arranged to control all the components of the engine zone of said motor vehicle and comprising a clock and hardware and software means for carrying out simulations and determining suitable strategies and for carrying out calculations for determining the presence or absence of a fault.

[0002] The invention also relates to a diagnostic method, by said control unit, for checking the opening of a flap included in a secondary air injection system of said thermal engine of said motor vehicle.

[0003] The invention relates to the field of thermal engines, in particular for motor vehicles. And, more particularly, the invention relates to the interrelated fields of powertrains (also called "GMP"), in particular thermal engines, hybrid applications, the air loop in the engine circuit, and the secondary air injection system usually called "S AI" (from the English "secondary air injection").

[0004] Historically, older versions of gasoline engines were not equipped with a secondary air injection system in the exhaust. However, it is possible to find this type of technology applied to engines sold in the USA for pollution control constraints. The systems found commercially are air injections in the exhaust via a secondary air circuit, which operates when the engine is running to create post-combustion in the exhaust manifold, consequently creating an increase in temperature upstream of the catalyst helping it to activate more quickly. These systems mainly operate with an air flow measurement via a flow meter.

[0005] The current architecture of the pollution control chain (catalyst, catalyst heating strategy) on board hybrid thermal engines made it possible to comply with emissions until the implementation of the new Euro 7 pollution control standards. Since the publication of this new standard and the associated level of emissions (mainly in very cold conditions), the pollution control system may prove insufficient.

[0006] Indeed, the implementation of the catalyst heating strategy is undertaken during starting. It is therefore possible that the priming of this catalyst is not effective when the thermal engine is started, mainly on hybrid applications, especially if the current driving cycle begins with purely thermal driving.

[0007] In order to improve the efficiency of the antipollution system, an important innovation consists of adding to the exhaust line a heating system annexed to the depollution system, by means of a heating grid and a secondary air injection system S AI comprising a pump and a controlled flap.

[0008] OBD ("on-board diagnostics") regulations require the monitoring by an electronic system of engine faults and failures linked to exhaust gas emissions, by analyzing parameters from sensors and computers fitted to the vehicle. These on-board diagnostic means are mandatory on vehicles with internal combustion engines in most states.

[0009] Due to this OBD regulation on the one hand, and for reasons of maintaining the heating grid on the other hand, it is necessary to check that the controlled shutter is opening correctly, in order to ensure that the air flow supplied by the pump can be correctly conveyed to the heating grid.

[0010] The objective of the present invention is to implement a solution adapted to this problem, by proposing means and a method for diagnosing the correct opening of the controlled flap of the S AI system, by jointly observing the evolution of the pressure within the S AI circuit (between the active and delivery pump and the controlled flap in opening), and the evolution of the power consumed by the pump when the SAI flap is open, with the aim of ensuring the correct operation of the SAI system and the routing of the air flow towards the heating grille.

[0011] To achieve this objective, the invention proposes a motor vehicle comprising a heat engine comprising a catalyst on its exhaust circuit, a control unit arranged to control all the components of the engine zone of said motor vehicle and comprising a clock and hardware and software means for carrying out simulations and determining suitable strategies and for carrying out calculations for determining the presence or absence of a fault.

[0012] According to the invention, the components of the engine zone of said motor vehicle comprise a preheating device, which constitutes an independent system for preheating said catalyst, said preheating device comprising a heating grid, which is positioned downstream of said engine and upstream of said catalyst, and a secondary air injection system which forms an air loop and comprises a pump and a flap controlled by said control unit, said secondary air injection system being located between, on the one hand, a compressor upstream, upstream of said engine, and, on the other hand, said heating grid, said pump being arranged to send air taken from said upstream compressor, via the control of said flap, to said heating grid to preheat said catalyst, the air flow produced by said pump being regulated by means of a pressure sensor which is implemented between said pump and said flap, and said control unit is arranged to develop, with reference to a calibration of said pump and a calibration of said pressure sensor, and on the basis of the power measured at said pump and the pressure measured by said pressure sensor, a diagnosis of opening of said flap.

[0013] Thanks to the invention, it is possible to improve the efficiency of the antipollution system with simple and small components, and also to comply with the antipollution standards which require manufacturers to equip vehicles with on-board diagnostic devices, capable of checking the quality of the air circuit and the exhaust circuit.

[0014] Advantageously, said control unit is programmed to diagnose the correct opening of said shutter controlled by said secondary air injection system on the basis of the continuous monitoring by said pressure sensor of the value of the pressure within said secondary air injection system, between said active pump delivering air and said shutter controlled in opening, and by a means of measuring intensity or flow the value of the power consumed by said electric or respectively pneumatic pump when said shutter is open, to check the correct operation of said secondary air injection system and the correct routing of the air flow towards said heating grille.

[0015] Thus the analysis and diagnosis are based on simple parameters which are the pressure in the air loop and the power consumed by the pump.

[0016] Advantageously, said control unit is interfaced with presence and / or proximity sensor means and / or with a door opening remote control, to control the operation of said preheating device prior to starting of said motor vehicle by a user.

[0017] This configuration makes it possible to prevent pollution peaks generally encountered during cold starts, thanks to preheating and thanks to the permanent monitoring of the parameters by the control unit.

[0018] The invention also relates to a diagnostic method, by said control unit, for checking the opening of said flap of said secondary air injection system of said thermal engine of said motor vehicle.

[0019] According to the invention, said diagnosis verifies that, when said pump is activated and delivering, the relative pressure within said secondary air injection system is greater than a pressure gauge depending on the rotation speed of said pump, and the power consumed by said pump when said flap is open is greater than a power gauge depending on the relative pressure measured by said sensor in said secondary air injection system.

[0020] This method compares pressure and power parameters, easy to measure with the means with which this vehicle is equipped at the level of its secondary air injection system, with pressure and power templates that the control means are able to calculate.

[0021] Advantageously, the shutter opening diagnosis comprises a first step of determining the activation conditions, followed, on the one hand, by a second step of calculating said pressure gauge as a function of the speed of said pump, said second step being followed by a second complementary step during which the pressure in said secondary air injection system is monitored, and on the other hand, by a third step of calculating said power gauge as a function of the pressure differential in said secondary air injection system, said third step being followed by a third complementary step during which the power consumed by said pump is monitored, and in that the results of the tests carried out during said second complementary step and said third complementary step are combined to determine whether or not said shutter has opened correctly.

[0022] The pressure and power parameters are thus treated separately, according to a simple iterative process.

[0023] More particularly, during said second step, said pressure template is determined in two sub-steps, in a first sub-step a fixed value of the detection threshold is determined as long as the pressure variation seen by said pressure sensor remains below the resolution value of said sensor resulting from a calibration of said sensor, and, in a second sub-step the detection threshold is determined as a function of the pressure variation curve of said pump, and, to guarantee the good robustness of said pressure template, the resolution of said pressure sensor, the maximum negative deviation allowed for a said aged pressure sensor, and a hysteresis less than or equal to 5% of the value of the pressure variation in said secondary air injection system are removed from said pressure variation curve.

[0024] The calculation of the pressure gauge is thus based on a calibration, which makes it possible to take into account any wear and tear of the pressure sensor.

[0025] More particularly, during said third step, said power template is determined in two sub-steps, in a first sub-step a fixed value of the detection threshold is determined as long as the power consumed by said pump remains equivalent between a power consumed by the pump with a said shutter open and that with a said shutter closed, said fixed detection threshold value being derived from a calibration of said pump and increased by a safety margin less than or equal to 5% of the consumed power value returned by said pump, and in a second sub-step the detection threshold is determined as a function of the power consumed by said pump, and, to guarantee the robustness of this power gauge, a safety margin less than or equal to minus 5% of the value returned by said pump is applied for said diagnosis of correct opening of said shutter, and a hysteresis of the value of the power consumed by said pump less than or equal to minus 5% of the value returned by the pump for said diagnosis of correct opening of said shutter.

[0026] The calculation of the pressure gauge is thus based on a calibration of the pump, carried out taking into account the open shutter and closed shutter situations.

[0027] Advantageously, said diagnosis detects the presence of a fault in opening said shutter by processing parameters which are the pressure in said secondary air injection system, the atmospheric pressure, a pressure threshold, according to said pressure template developed during said second step, a hysteresis to take into account any variations in rotation speed experienced by said pump, the power consumed by said pump, a power threshold, according to said power template developed during said third step, by means of operators which are an adder of said atmospheric pressure, said pressure threshold, and said hysteresis, a first “greater than or equal” comparator between said pressure in said secondary air injection system and the output result of the calculation carried out by said adder, a second “greater than or equal” comparator between said power consumed and said power threshold,a logical operator “AND” between the output results of said first comparator and said second comparator, to arrive at outcomes of the algorithm which are an “absence of fault” if said pressure in said secondary air injection system is greater than or equal to the total of said atmospheric pressure, said pressure threshold, and said hysteresis, and if said power consumed is greater than or equal to said power threshold, or a “fault detected with shutter closed” otherwise.

[0028] In this way, once the pressure and power templates have been determined, a reliable diagnosis is achieved.

[0029] Advantageously, the diagnosis of the correct opening of said controlled flap is carried out by respecting a timing diagram according to which, at an initial instant determined by said control unit on the basis of a signal from presence and / or proximity sensors or a command made by the user of said motor vehicle, said pump is active and delivering, said flap is still closed, the pressure in said secondary air injection system is already established at a pressure level lower than its maximum level, the power of said pump is already established at a power level lower than its maximum level, then at a first instant subsequent to said initial instant said pump is active and delivering, said flap is open, the pressure in said secondary air injection system is established at a pressure level lower than its maximum level, the power of said pump is established at a power level lower than its maximum level, then at a second instant subsequent to the first instant, said pump is active and delivering, said flap is open, the pressure in said secondary air injection system is stabilized at its maximum level, the power of said pump is stabilized at its maximum level, and the flap opening diagnosis S AI begins to end at a third instant subsequent to the second instant and at which said diagnosis determines whether said flap has correctly opened, and whether the air flow produced by said pump can be correctly routed to said heating grid.

[0030] This ensures the solidity of the diagnosis to the protection of the heating grid.

[0031] The invention will be further detailed by the description of non-limiting embodiments, and on the basis of the appended figures illustrating variants of the invention, in which: - [Fig.l] illustrates schematically and partially, a motor vehicle comprising a gasoline engine equipped in particular with a secondary air injection system SAI according to the invention, with a pump, a controlled flap, and a pressure sensor; - [Fig.2] illustrates schematically, in the form of a chronogram with a common scale on the abscissa, five graphs illustrating, from top to bottom, the state of the pump, the state of the shutter, the pressure in the SAI system, the power of the pump, and the performance of the diagnostic check of the opening of the shutter according to the invention “SAI shutter opening”; - [Fig.3] schematically illustrates the evolution of pressure within the system SAI on the ordinate, as a function of the pump rotation speed on the abscissa; the upper curve in solid line corresponds to the pressure measured with the shutter open, the lower curve in broken line to that measured with the shutter closed; - [Fig.4] schematically illustrates the evolution of the power consumed by the SAI system pump on the ordinate, as a function of the pressure differential or delta measured by the sensor on the abscissa; the upper curve in solid line corresponds to the power consumed with the shutter open, the lower curve in broken line to that consumed with the shutter closed; the increase in power when the shutter is opened is clearly visible; - [Fig.5] schematically illustrates the stages of carrying out the diagnosis “shutter opening”; - [Fig.6] schematically illustrates the shape of the pressure gauge on the ordinate (lower curve in dotted line) as a function of the pump speed in abscissa; the upper curve in solid line corresponds to the open shutter, the intermediate curve in broken line to the closed shutter; - [Fig.7] schematically illustrates the shape of the consumed power gauge by the pump on the ordinate (dotted line curve) as a function of the air pressure on the abscissa; the upper curve in solid line corresponds to the open flap, the intermediate curve in broken line to the closed flap; - [Fig.8] schematically illustrates a detection method algorithm for determining the absence of a defect or the presence of a detected defect.

[0032] The invention aims to create a specific diagnostic to verify the correct opening of the controlled flap of the SAI system. This verification is mandatory within the framework of the OBD regulation (implementation of this regulation in 2025) for Euro 7 engines equipped with an SAI system, and is necessary to guarantee the mechanical strength of the heating grille via the blown air flow. Given the fact that hybrid gasoline engines meeting the Euro 7 conditions will be the first applications to be equipped with an SAI system, it is necessary to create a diagnostic, which did not previously exist.

[0033] The invention thus relates to a diagnostic specifically developed to meet the requirement of verifying the correct opening of the on-board controlled flap on Euro 7 hybrid petrol engines.

[0034] The invention thus relates to a diagnostic specifically developed to meet the requirement of verifying the correct opening of the on-board controlled flap on Euro 7 hybrid petrol engines.

[0035] [Fig. 1] illustrates the means implemented within the framework of the invention to improve the performance of the anti-pollution system on Euro 7 hybrid gasoline engines, for a motor vehicle 1000 comprising at least one thermal engine 500, in particular gasoline, comprising a catalyst 1 on its exhaust circuit.

[0036] For this purpose, the motor vehicle 1000 has a preheating device 100 on board. This preheating device 100 is an independent system for preheating the catalyst 1: this preheating device 100 comprises a heating grid 2, which is positioned downstream of the engine 500 and upstream of the catalyst 1, and a secondary air injection system 3. This secondary air injection system 3, or SAI, forms an air loop and comprises a pump 4 and a flap 5, both controlled, and is located between the upstream compressor 6, upstream of the engine 500, and the heating grid 2.

[0037] The preheating device 100 is designed to be used before starting the vehicle, preferably when detecting the presence of the driver near the vehicle by presence and / or proximity sensor means 200 connected to a control unit 2000 that the vehicle 1000 comprises, or when the actuation of a door opening control, or similar. This control unit 2000 is arranged to control all the components of the engine zone, and includes a clock and the hardware and software means to carry out simulations and determine the appropriate strategies, and to carry out calculations for determining the presence or absence of a fault.

[0038] The air produced by the pump 4 is sent towards the heating grid 2 via the control of the flap 5, and allows the heating grid 2 to preheat the catalyst 1, and also to guarantee the good performance of the heating grid 2 (prevents the heating grid 2 from overheating).

[0039] The air produced is regulated by means of a pressure sensor 7, which is implemented between the pump 4 and the flap 5. More particularly and non-limitingly, this sensor 7 is both a pressure sensor and a temperature sensor.

[0040] To ensure the proper functioning of the flap 5 during an opening request, and to comply with OBD regulations, a specific diagnosis has been developed. In order to carry out the diagnosis under the best conditions, i.e. pump 4 activated and delivering, flap 5 opening request, pump 4 power and pressure in the SAI 3 system measured by sensor 7 stabilized, the diagnostic sequence for the proper opening of the controlled flap 5 must comply with the timing diagram according to [Fig.2].

[0041] This timing diagram displays on five graphs A, B, C, D, E, the parameters of the different functions at different successive times, t0, t1, t2, t3, on a common time scale on the abscissa.

[0042] At the initial time tO:

[0043] - graph A indicates that pump 4 is active and delivering;

[0044] - graph B indicates that shutter 5 is closed;

[0045] - graph C indicates that the pressure in the secondary air injection system 3 is already established, at a pressure level lower than its maximum level;

[0046] - graph D indicates that the power of pump 4 is already established, at a level of power below its maximum level;

[0047] - graph E indicates that the SAI shutter opening diagnosis is not yet carried out.

[0048] At a first instant tl subsequent to the previous tO:

[0049] - graph A indicates that pump 4 is active and delivering;

[0050] - graph B indicates the opening of shutter 5;

[0051] - graph C indicates that the pressure in the secondary air injection system 3 is established at a level lower than its maximum level;

[0052] - graph D indicates that the power of pump 4 is established, at a lower level at its maximum level;

[0053] - graph E indicates that the SAI shutter opening diagnosis is not yet carried out.

[0054] At a second time t2 after the previous time tl:

[0055] - graph A indicates that pump 4 is active and delivering;

[0056] - graph B indicates that shutter 5 is open;

[0057] - graph C indicates that the pressure in the secondary air injection system 3 is stabilized at its maximum level;

[0058] - graph D indicates that the power of pump 4 is stabilized at its level maximum;

[0059] - graph E indicates the start of the S AI shutter opening diagnosis.

[0060] At a third time t3 after the previous time t2:

[0061] - graph A indicates that pump 4 is active and delivering;

[0062] - graph B indicates that shutter 5 is open;

[0063] - graph C indicates that the pressure in the secondary air injection system 3 is stabilized at its maximum level;

[0064] - graph D indicates that the power of pump 4 is stabilized at its level maximum;

[0065] - graph E indicates the end of the SAI shutter opening diagnosis.

[0066] This diagnosis is therefore carried out after a request to open the flap 5 of the SAI system 3 and after the activation of the pump 4, with the aim of checking whether the flap 5 has opened correctly, and whether the air flow produced by the pump 4 can be correctly routed to the heating grid 2.

[0067] The diagnosis of correct opening of the shutter 5 is based on the combined observation, on the one hand of the evolution of the pressure within the SAI system 3 - which is measured by the sensor 7 - when the pump 4 is activated, and on the other hand of the evolution of the power consumed by the pump 4 when the shutter 5 is controlled in opening.

[0068] Indeed, when the pump 4 is activated and delivering, the relative pressure within the SAI system 3 must be greater than a pressure gauge depending on the rotation speed of the pump 4 as shown in [Fig.3], and the power consumed by the pump 4 when the shutter is open must be greater than a gauge depending on the relative pressure measured by the sensor 7 as shown in [Fig.4].

[0069] Thus, the detection threshold of the pressure level reached in the circuit of the SAI system 3 will take the form of a template depending on the rotation speed of the pump 4, and, on the other hand, the detection threshold of the power level consumed by the pump 4 will take the form of a template depending on the pressure delta measured in the SAI system 3 via the pressure sensor 7.

[0070] [Fig.5] schematically illustrates the functional design of the diagnosis of the correct opening of shutter 5, and the different stages of carrying out the “shutter opening” diagnosis.

[0071]

[0072]

[0073]

[0074]

[0075]

[0076]

[0077] Step 10 “activation conditions” consists of determining all the activation conditions to guarantee, on the one hand, the correct completion of the opening diagnosis of shutter 5, and on the other hand good robustness of this same diagnosis. A suitable list of activation conditions for carrying out this diagnosis, which is not exhaustive, includes: - engine not running (activation phase of the catalyst preheating strategy); - request for activation of the S AI 3 system by a control function of the heating grid 2; - battery voltage included in a range of values ​​representative of its proper functioning, to guarantee the robustness of the control of the pump motor 4; - request to open the controlled shutter 5; - no request for inhibition of the diagnosis by a diagnostic management module, which is included in the control unit 2000, following detection of a fault present on the sensor 7 and / or the pump 4 and / or the flap 5; - pump speed 4 greater than a threshold for which the pressure measured by pressure sensor 7 is greater than the measurement accuracy of this same sensor. This list of activation conditions for performing the diagnosis can be supplemented, following feedback, for a new engine application, a new component of the SAI 3 system, or any other improvement. Step 20 “calculation of the pressure gauge as a function of the pump speed” consists of determining the pressure gauge as a function of the speed of pump 4. The template must take into account, at a minimum, the following elements to guarantee the robustness of the detection threshold: - internal temperature of the pump; - compensation linked to a battery voltage deviating from the nominal value. In order to ensure optimal robustness of the template to environmental variations, the rotation speed of the pump 4 is corrected in terms of atmospheric pressure and / or ambient air temperature. These compensations, which can be activated or deactivated independently via specific Booleans, make it possible to relate, as a function of the variations undergone by the atmospheric pressure and / or the ambient air temperature, the rotation speed of the pump 4 to an equivalent rotation speed which would be measured under the nominal conditions of atmospheric pressure and ambient air temperature. Thus, a single calibration of this template carried out on the engine test bench under nominal conditions of atmospheric pressure and ambient air temperature is sufficient. to ensure the robustness of the diagnostic detection threshold. This template has the appearance visible in [Fig.6].

[0078] More particularly, the pressure gauge is determined in two sub-steps 21 and 22:

[0079] - the first sub-step 21 consists of determining a fixed value of the threshold of detection as long as the pressure variation seen by the pressure sensor 7 of the SAI 3 system remains below or close to the resolution value of the sensor 7. This fixed detection threshold value must therefore be calibrated according to the technical definition of the sensor implemented on the engine application concerned to which a safety margin must be added which corresponds to the maximum positive deviation allowed for an aged pressure sensor.

[0080] - the second sub-step 22 consists of determining the detection threshold as a function of the SAI pressure variation curve produced by the supplier of pump 4 of the SAI system 3 (if this curve is not supplied by the supplier, it is possible to identify this curve on a component and / or engine bench by measuring the value of the SAI pressure variation by carrying out sweeps of the rotation speeds of the SAI pump, and this, under conditions of atmospheric pressure and ambient air temperature called normal (respectively 101325 Pa and 20°C). To guarantee the robustness of this pressure gauge, the following elements must be removed from this pressure variation curve: - resolution of pressure sensor 7 of the SAI 3 system; - maximum negative deviation allowed for an aged pressure sensor; - hysteresis of the order of 5% of the value of the SAI pressure variation which will cover variations in atmospheric pressure (e.g., rise in altitude) and / or ambient temperature, and also take into account oscillations that can be observed on a pump rotation speed measurement signal. The order of magnitude can be adapted following supplier feedback (e.g., better resolution of the pump speed or oscillations seen on the pump speed that are greater than expected) and / or following validation tests on a component, engine, or vehicle bench.

[0081] Step 25 “performing monitoring of the pressure of the SAI circuit” consists of checking the pressure level reached in the SAI circuit via the pressure sensor 7: this diagnosis is carried out by comparing the value from the SAI pressure sensor 7 with the detection threshold from the template calculated in step 20, to which the value of the measured atmospheric pressure is added as well as a hysteresis to take into account any variations in rotation speed experienced by the pump 4. It is noted that, in the case of a relative SAI pressure sensor 7 (i.e. where the pressure value returned by the sensor is already the differential value between the pressure measured in the SAI circuit and atmospheric pressure), then the value from the S AI pressure sensor 7 is only compared to the detection threshold from the template calculated in step 20.

[0082] A confirmation time which varies depending on the rotation speed of the pump 4, and which is compensated as needed depending on the atmospheric pressure, is set up at the output of the diagnosis in order to consider only the actual faults present (in particular not to take into account furtive faults or transient phenomena).

[0083] Step 30 “calculation of the power gauge as a function of the pressure delta in the SAI system” consists of determining the power gauge consumed by the pump 4 as a function of the pressure level reached in the SAI circuit and which is measured via the pressure sensor 7. In the case of an absolute SAI 7 pressure sensor, then the value of the atmospheric pressure measured by the sensor on board the vehicle is subtracted from the value from the SAI 7 pressure sensor. In the case of a relative SAI 7 pressure sensor, then the value from the sensor is used without modification to determine the diagnostic detection threshold. This gauge has the appearance visible in [Fig.7].

[0084] More particularly, the power template is determined in two sub-steps 31 and 32:

[0085] - the first sub-step 31 consists of determining a fixed value of the threshold of detection as long as the power consumed by the SAI pump remains equivalent between a power consumed by the pump with an open SAI flap and that with a closed flap (in order to avoid false detection). This fixed detection threshold value must therefore be calibrated according to the technical definition of the pump on board the engine application concerned to which a safety margin must be added which can, initially, be set at +5% of the consumed power value returned by the pump;

[0086] - the second sub-step 32 consists of determining the detection threshold as a function of the power consumed by the SAI pump produced by the pump supplier (if this curve is not supplied by the supplier, it is possible to identify this curve on a component and / or engine bench by measuring the value of the voltage and current consumed (in order to calculate the power consumed = voltage consumed x current consumed) by the SAI pump by carrying out sweeps of rotation speeds of the SAI pump - and consequently of variations in SAI pressures - and this, in conditions of atmospheric pressure and ambient air temperature called normal (respectively 101325 Pa and 20°C). To guarantee the good robustness of this pressure gauge, the following elements must be taken into account: - safety margin which can, initially, be set at: • less than 5% of the value returned by the pump for the diagnosis of correct opening of the shutter; - hysteresis of the value of the power consumed by the SAI pump which will cover variations undergone by the atmospheric pressure (e.g. rise in altitude) and / or the ambient temperature. The order of magnitude can be adapted following a supplier return (e.g.: poorly estimated power consumption) and / or following validation tests on a component or engine or vehicle bench. The value of this hysteresis can be set at: • less than 5% of the value returned by the pump for the diagnosis of correct opening of the shutter.

[0087] Step 35 “performing monitoring of the power consumed by the pump” consists of checking the level of power consumed by the pump 4 when the latter is active and the shutter 5 is controlled to open: this diagnosis is carried out by comparing the value resulting from the power consumed by the pump 4 with the detection threshold resulting from the template calculated in step 30.

[0088] A variable confirmation time, which is compensated as needed according to atmospheric pressure, is implemented at the output of the diagnosis in order to consider only the actual faults present (in particular not to take into account stealth faults or transient phenomena).

[0089] The combination of the result of the two tests carried out respectively in steps 25 and 35 makes it possible to determine whether the shutter has opened correctly or not.

[0090] [Fig.8] summarizes the method of detecting the present fault. The input quantities of the algorithm are:

[0091] -41 SAI pressure;

[0092] - 42 atmospheric pressure;

[0093] - 43 pressure threshold, according to the pressure template developed in step 20 visible in [Fig.6] ;

[0094] - 44 a hysteresis;

[0095] - 45 power consumed;

[0096] - 46 power threshold, according to the power template developed in step 30 visible in [Fig.7].

[0097] The operators of the algorithm are:

[0098] - 51 adder of quantities 42 atmospheric pressure, 43 pressure threshold, 44 hysteresis;

[0099] - 52 first comparator (greater than or equal to) between the magnitude 41 SAI pressure and the output result of the calculation performed by adder 51;

[0100] - 53 second comparator (greater than or equal to) between the magnitude 45 power consumed and the magnitude 46 power threshold;

[0101] - 54 logical operator “AND” between the output results of the first comparator 52 and the second comparator53.

[0102] The outcomes of the algorithm are:

[0103] - 47 “absence of fault” if the SAI 41 pressure is greater than or equal to the total of the atmospheric pressure 42, pressure threshold 43, and hysteresis 44, and if the consumed power 45 is greater than or equal to the power threshold 46;

[0104] - 48 “fault detected shutter closed” if the SAI 41 pressure is greater than or equal to total of atmospheric pressure 42, pressure threshold 43, and hysteresis 44, and if the consumed power 45 is less than the power threshold 46;

[0105] - 49 “closed shutter detected fault”, if the SAI 41 pressure is lower than the total of the atmospheric pressure 42, pressure threshold 43, and hysteresis 44, and if the consumed power 45 is greater than the power threshold 46 after a confirmation time has elapsed.

[0106] In short, the invention makes it possible, via a new diagnosis, to ensure the correct functioning of the SAI system component, and consequently, compliance with OBD regulations and anti-pollution standards, in particular Euro 7.

[0107] This solution makes it possible to reduce costs compared to other on-board solutions such as the installation of a specific flow meter, the volume of which is larger and therefore more difficult to properly install in the engine area, and / or a flap position copy sensor. The invention therefore provides an economical and reliable response to the problem posed.

Claims

Claims

1. Motor vehicle (1000) comprising a heat engine (500) comprising a catalyst (1) on its exhaust circuit, a control unit (2000) arranged to control all the components of the engine zone of said motor vehicle (1000) and comprising a clock and hardware and software means for carrying out simulations and determining suitable strategies and for carrying out calculations for determining the presence or absence of a fault, characterized in that the components of the engine zone of said motor vehicle (1000) comprise a preheating device (100), which constitutes an independent system for preheating said catalyst (1), said preheating device (100) comprising a heating grid (2), which is positioned downstream of said engine (500) and upstream of said catalyst (1),and a secondary air injection system (3) which forms an air loop and comprises a pump (4) and a flap (5) controlled by said control unit (2000), said secondary air injection system (3) being located between on the one hand a compressor upstream (6), upstream of said engine (500), and on the other hand said heating grid (2), said pump (4) being arranged to send air taken from said compressor upstream (6), via the control of said flap (5), to said heating grid (2) to preheat said catalyst (1), the air flow produced by said pump (4) being regulated by means of a pressure sensor (7) which is implemented between said pump (4) and said flap (5), and characterized in that said control unit (2000) is arranged to develop, with reference to a calibration of said pump (4) and a calibration of said pressure sensor (7),and on the basis of the power measured at said pump (4) and the pressure measured by said pressure sensor (7), a diagnosis of opening of said shutter (5).,

2. Motor vehicle (1000) according to claim 1 characterized in that said control unit (2000) is programmed to diagnose the correct opening of said flap (5) controlled by said secondary air injection system (3) on the basis of the continuous monitoring by said pressure sensor (7) of the value of the pressure within said secondary air injection system (3), between said active pump (4) delivering air and said flap (5) controlled in opening, and by a means of measuring intensity or flow the value of the power consumed by said electric or respectively pneumatic pump (4) when said flap (5) is opened, to check the correct operation of said secondary air injection system (3) and the correct routing of the air flow to said heating grid (2).

3. Motor vehicle (1000) according to claim 1 or 2 characterized in that said control unit (2000) is interfaced with presence and / or proximity sensor means (200) and / or with a door opening remote control, to control the operation of said preheating device (100) prior to starting of said motor vehicle (1000) by a user.

4. Diagnostic method, by said control unit (2000), for checking the opening of said flap (5) of said secondary air injection system (3) of said heat engine (500) of said motor vehicle (1000) according to any one of claims 1 to 3 characterized in that said diagnostic verifies that, when said pump (4) is activated and delivering, the relative pressure within said secondary air injection system (3) is greater than a pressure gauge depending on the rotation speed of said pump (4), and the power consumed by said pump (4) when said flap (5) is open is greater than a power gauge depending on the relative pressure measured by said sensor (7) in said secondary air injection system (3).

5. Diagnostic method according to claim 4 characterized in that the shutter opening diagnosis comprises a first step (10) of determining the activation conditions, followed, on the one hand, by a second step (20) of calculating said pressure gauge as a function of the speed of said pump (4), said second step (20) being followed by a second complementary step (25) during which the pressure in said secondary air injection system (3) is monitored, and on the other hand, by a third step (30) of calculating said power gauge as a function of the pressure differential in said secondary air injection system (3), said third step (30) being followed by a third complementary step (35) during which the power consumed by said pump (4) is monitored,and in that the results of the tests carried out during said second complementary step (25) and said third complementary step (35) are combined to determine whether said shutter (5) has opened correctly or not.,

6. Diagnostic method according to claim 5 characterized in that, during said second step (20), said pressure gauge is determined in two sub-steps, in a first sub-step (21) a fixed value of the detection threshold is determined as long as the pressure variation seen by said pressure sensor (7) remains below the resolution value of said sensor (7) resulting from a calibration of said sensor (7), and, in a second sub-step (22) the detection threshold is determined as a function of the pressure variation curve of said pump (4), and, to guarantee the good robustness of said pressure template, the resolution of said pressure sensor (7), the maximum negative deviation admitted for an aged said pressure sensor (7) and a hysteresis less than or equal to 5% of the value of the pressure variation in said secondary air injection system (3) are removed from said pressure variation curve.

7. Diagnostic method according to claim 5 or 6 characterized in that, during said third step (30), said power template is determined in two sub-steps, in a first sub-step (31) a fixed value of the detection threshold is determined as long as the power consumed by said pump (4) remains equivalent between a power consumed by the pump with a said shutter (5) open and that with a said shutter (5) closed, said fixed detection threshold value being derived from a calibration of said pump (4) and increased by a safety margin less than or equal to 5% of the power consumed value returned by said pump (4) for said diagnosis of proper opening of said shutter, and in a second sub-step (32) the detection threshold is determined as a function of the power consumed by said pump (4), and, to guarantee the good robustness of this power template,a safety margin less than or equal to minus 5% of the value returned by said pump (4) is applied, and a hysteresis of the value of the power consumed by said pump (4) less than or equal to minus 5% of the value returned by the pump for said diagnosis of correct opening of said shutter.,

8. Diagnostic method according to any one of claims 5 to 7 characterized in that said diagnosis detects the presence of a fault in the opening of said flap (5) by processing parameters which are the pressure (41) in said secondary air injection system (3), the atmospheric pressure (42), a pressure threshold (43), according to said pressure template developed during said second step (20), a hysteresis (44) to take into account any variations in rotation speed experienced by said pump (4), the power (45)

9. consumed by said pump (4), a power threshold (46), according to said power template developed during said third step (30), by means of operators which are an adder (51) of said atmospheric pressure (42), of said pressure threshold (43), and of said hysteresis (44), a first comparator (52) “greater than or equal” between said pressure (41) in said secondary air injection system (3) and the output result of the calculation carried out by said adder (51), a second comparator (53) “greater than or equal” between said consumed power (45) and said power threshold (46), a logical operator “AND” (54) between the output results of said first comparator (52) and said second comparator (53), to arrive at outcomes of the algorithm which are an “absence of fault” (47) if said pressure (41) in said secondary air injection system (3) is greater than or equal to the total of said atmospheric pressure (42),said pressure threshold (43), and said hysteresis (44), and if said consumed power (45) is greater than or equal to said power threshold (46), or a “closed flap detected fault” (48, 49) otherwise. Diagnostic method according to any one of claims 4 to 8 characterized in that the diagnosis of the correct opening of said controlled flap (5) is carried out by respecting a timing diagram according to which, at an initial time (t0) determined by said control unit (2000) on the basis of a signal from presence and / or proximity sensors (200) or a command made by the user of said motor vehicle (100), said pump (4) is active and delivering, said flap (5) is still closed, the pressure in said secondary air injection system (3) is already established at a pressure level lower than its maximum level, the power of said pump (4) is already established at a power level lower than its maximum level,then at a first instant (tl) subsequent to said initial instant (tO) said pump (4) is active and delivering, said flap (5) is open, the pressure in said secondary air injection system (3) is established at a pressure level lower than its maximum level, the power of said pump (4) is established at a power level lower than its maximum level, then at a second instant (t2) subsequent to the first instant (tl), said pump (4) is active and delivering, said flap (5) is open, the pressure in said secondary air injection system (3) is stabilized at its maximum level, the power of said pump (4) is stabilized at its maximum level, and the SAI flap opening diagnosis begins to end at one, third instant (t3) subsequent to the second instant (t2) and at which said diagnosis determines whether said shutter (5) has opened correctly, and whether the air flow produced by said pump (4) can be correctly routed to said heating grid (2).

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