WO2013190365A2

WO2013190365A2 - Method for monitoring and reducing the polluting emissions of vehicles

Info

Publication number: WO2013190365A2
Application number: PCT/IB2013/001291
Authority: WO
Inventors: Agnès LEGRAND
Original assignee: Air B.E.
Priority date: 2012-06-21
Filing date: 2013-06-20
Publication date: 2013-12-27
Also published as: WO2013190365A3

Abstract

The invention relates to a method for comparing and reducing the polluting emissions of a motor vehicle, comprising the steps involving: by means of a probe for analysing exhaust gases, detecting the emissions of a vehicle during a test of the engine under given running conditions; establishing an actual footprint corresponding to the vehicle on which the emissions are measured; comparing the actual footprint obtained to a standard footprint corresponding to the vehicle on which the emissions are measured; depending on the deviations measured between the two footprints, determining a corrective action to be carried out on the vehicle in order to reduce the polluting emissions of same.

Description

METHOD OF CONTROLLING AND REDUCING EMISSIONS

POLLUTANTS OF VEHICLES

TECHNICAL FIELD OF THE INVENTION [0001] The present invention relates to a method for controlling, monitoring and reducing polluting emissions of vehicles.

STATE OF THE PRIOR ART [0002] Patent application FR 2 919 671 proposes a method for diagnosing a diesel engine for determining whether this engine or at least one member associated with it is affected by one or more malfunctions. negatively affecting the degree of pollution of the exhaust gases produced by this engine. The method comprises the steps of analyzing the rate of carbon dioxide (CO2) or the evolution of this rate in these exhaust gases, alone or in combination with the rate or evolution of the rate of another gas, according to a predetermined state of the engine and to characterize, from said analysis, the possible malfunction (s) affecting the diesel engine and / or the organ (s) associated with it. However, this method does not make it possible to obtain pollutant emission values. Moreover, it does not make it possible to determine corrective actions in a broader manner according to various types of pollution caused by the vehicle diagnosed.

[0003] WO2010 / 028082 discloses a method and apparatus for determining the reduction of actual pollution resulting from the operation of an electric vehicle in place of an internal combustion equivalent. An onboard data logger uses data from an energy counting device. The accumulated data is stored in a secure memory and is periodically transmitted to a remote data center using a secure connection. At the remote processing center, the accumulated data is evaluated and converted into a uniform representation pollution reduction. The proposed solution only concerns electric vehicles, and does not allow, for example, to determine the data in relation to a fleet of vehicles with a combustion engine. To overcome these disadvantages, the invention provides different technical means.

SUMMARY OF THE INVENTION

First, a first object of the invention is to provide a method for determining the exact amounts of pollutants emitted by the vehicles. Another object of the invention to provide a method for determining corrective actions to be provided to a vehicle (or a fleet of vehicles) based on the results of pollutant measurements.

To do this, the invention provides a method for controlling and reducing vehicle emissions comprising the steps of:

• using a vehicle exhaust gas test probe, detect the gases emitted by the vehicle during an engine test under given operating conditions;

• determine the actual distribution of the gases emitted (effective footprint) by the vehicle on which the measurements are made;

• compare the actual distribution obtained with a typical distribution corresponding to the vehicle on which the gases are measured;

• Based on measured discrepancies between the two distributions, determine corrective action (among pre-established test cases) to be performed on the vehicle in order to reduce the pollutant emissions of the vehicle, ie by decreasing the deviation from the standard or reference distribution.

According to an advantageous embodiment, the atmospheric footprint comprises emission data in relative value (% or ppmv) measured on at least the following gases: CO, CO2, NO, NO2, NOx (calculated), HC and NH3. Particulate emissions (PM10, PM2.5) can be estimated using an opacimeter or other suitable method. According to an advantageous embodiment, the distribution by gas is established on a multi-axis polygon-shaped graph (preferably a pentagon) whose number of axes corresponds to the number of gases. This distribution forms an identifiable profile or shape or footprint comparable to reference profiles or shapes or footprints.

According to yet another advantageous embodiment, the pentagon indicates the following gases, angularly distributed around the polygon in the following order, in the clockwise direction: CO2 + O2, CO2, CO, HC, NOx. According to another advantageous embodiment, the method further comprises a step of measuring the flow of the vehicle exhaust gas (by direct or indirect measurement).

According to another advantageous embodiment, the method further comprises the steps of:

• determine, from the relative data of each gas and the flow data of all the gases emitted, the flow rate for each of the gases;

• determine, for a reference period, the corresponding mass of gas emitted by the vehicle for at least one gas and preferably the following gases or pollutants O2, CO, CO2, NO, NO2, NOx (calculated), HC, NH3 and particles (PM10, PM2.5).

Taking into account the particles can be obtained by direct measurement (eg SMPS or impactor) or by extrapolation from a standard measurement opacity. It is a question of defining the relations making it possible to pass relative concentrations (ppmv or%) to the real concentrations (g / km or g / min). According to another advantageous example of embodiment, the transition to the real concentrations is determined using the following relations:

[0015] Basic data:

- TCO2 (g / km): CO2 emission rate in grams per kilometer

- rCO2 (ppmv): Volume mixing ratio of CO2 in the exhaust air

- rX (ppmv): Volumetric mixing ratio of the pollutant X (NOx, HC, ...) in the exhaust air

We want to find: TX (g / km) pollutant emission rate X (NOx, HC, ...) per kilometer. We have :

- Cx: concentration of the pollutant X in the exhaust air

mass contained in 1 m ³ of exhaust gas.

- Vikm: Volume of exhaust gas emitted over 1 km in m3.

Calculation of CX We have by definition:

γ

r _x (ppmv) = 10 ⁶ - (2)

* E

With:

- VX: volume of pollutant X in m3

- VE: Exhaust volume in m3

The law of perfect gases (which must remain a good approximation for exhaust gases) gives us:

PV _x = n _x RT = RT (3)

With:

- P: exhaust gas pressure in Pa - T: Exhaust gas temperature in ° K

- n _x : number of moles of pollutant X

- m _x : pollutant mass X in g.

- M _x : molar mass of pollutant X in g / mole

- R: perfect gas constant

So we have

m _x RT

V _x =

M _x P By carrying out the substitution in (2), we obtain: r _x (ppmv) = 10 ⁶ ^ ---

x V _E M _x P

By definition, the concentration of pollutant X is the ratio of m _x to V _E. So we have :

1 RT

r _x (ppmv) = l0 ⁶ C _x

M _x P

Therefore

At this level of the relationship, with Cx, the concentration of the pollutant X in the exhaust air in g / m3 (mass contained in 1 m ³ of exhaust gas), it is therefore possible to deduce the amount pollutant in g / min, via flow measurement (in L / min).

In order to reach g / km, it remains to determine the volume Vikm-

Calculation of V1 km:

Equation 1 can be applied for CO2

Therefore : C02

c (5)

C02

Moreover one can also apply equation (4) for CO2, so

M

r C02 - "- ¹ COI

(6)

10 "RT

So (substituting 6 in 5

Expression

Finally, substituting 4 and 7 in 1, we obtain: r M _v P 10 ⁶ T, COI

10 ⁶ RT ^r C02 ^ C02

- r _x : Volume mixing ratio of the pollutant X (NOx, HC, ...) in the exhaust air in ppmv.

- rco2: Volume mixing ratio of CO2 in the exhaust air in ppmv.

- Μχ: molar mass of pollutant X in g / mol

- M _C o2: molar mass of CO2 in g / mol

- _C o2: CO2 emission rate in grams per kilometer

- T _x : Pollutant emission rate X in grams per kilometer

The passage of the values relative to real values therefore requires the measurement in real time of the TCO2 temperature, the pressure and the flow, as well as the measurement of the real CO2 emission rate, under the same conditions of measurement of the pollutants to the exhaust by any suitable process. According to another advantageous embodiment, the method further comprises a step of performing a new exhaust gas control measurement after the corrective action has been performed on the vehicle. This approach measures or quantifies the progress of corrective action on the vehicle. For example, the three footprints (before / after and reference values) are represented in relative values and in real values in the form of radar graphs to visualize the gains.

According to another advantageous embodiment, the flow measurement comprises the steps of:

• using a temperature sensor (eg a K thermocouple), measure the average temperature of the exhaust gas;

• using a pressure sensor (for example a Pitot tube or a piezoelectric sensor), measure the average pressure of the exhaust gases;

· Determine the corresponding gas flow.

According to another advantageous embodiment, the method further comprises a step consisting in:

• carry out a data sharing BEFORE and AFTER the corrective action (theoretical or realized) for a set of vehicles for which the gas analysis measurements are made;

^• make a comparison between the global emissions AFTER correction and the global emissions potentially emitted if the corrective actions had not been carried out.

Preferably, a comparison is made to the specific data of the new vehicle (g / km) and the difference is determined. One can also consolidate the exploitation of the real data resulting from the measurements by the development of adapted algorithms.

With the aid of adapted software, it is advantageous to consolidate the exploitation of real data from measurements on the one hand with consolidation of information for example at the scale of a fleet and secondly with consolidation on a very large scale. The complexity of very large databases (see Big Data) implies the implementation of IT resources with significant processor capacity and data storage.

• compare overall emission data for the set of vehicles with global reference data;

• Based on measured discrepancies between the overall baseline data and the actual data compiled, determine an overall corrective action to be performed on at least a portion of the vehicles in order to reduce pollutant emissions to an overall level.

DESCRIPTION OF THE FIGURES

All the details of implementation are given in the description which follows, supplemented by FIGS. 1 to 7, presented solely for purposes of non-limiting examples, and in which:

FIG. 1 shows the key steps of the method for controlling and reducing the polluting emissions of vehicles according to the invention, in a single-vehicle version;

- Figure 2 shows the key steps of the process for controlling and reducing vehicle emissions for a set of vehicles;

FIG. 3 illustrates an example of a footprint for a vehicle subject to control and a possible corrective action;

FIGS. 4 to 7 illustrate examples of gas distributions or cavities for different cases of engine operation. DETAILED DESCRIPTION OF THE INVENTION

Figure 1 shows the key steps of the process for controlling and reducing the polluting emissions of vehicles according to the invention, in single-vehicle version. At the stage 10, an overall measurement of the exhaust gas is performed using a probe adapted to the vehicle under test. This probe makes it possible to identify (step 20) the gases present in the ejected gases. In step 30, a determination of the distribution of gases for the vehicle is made in relative values. Step 40 provides a comparison of the resulting distribution resulting from the measurements to a standard distribution corresponding to the vehicle tested. In step 50, an identification is made of the differences between the actual measured distribution and the standard distribution. This identification then makes it possible to proceed, in step 60, to an identification of a corrective action to be performed on the vehicle.

Figure 2 shows the key steps of the process for controlling and reducing the polluting emissions of vehicles according to the invention for a set of vehicles. In step 110, measurements are made on a set of vehicles. These measurements then make it possible to determine, in step 120, the average deviations for all the vehicles in the set. In step 130, an identical corrective action for the set of vehicles is identified. The following steps, 140 to 160 are optional. In step 140, it is intended to correct the vehicles of the assembly using the corrective action identified. In order to verify or validate the effectiveness of the corrections made, step 150 provides for performing measurements after correction, to possibly determine, at step 160, the overall emission reduction for at least one of the gases.

The measurements can be made from existing diagnostic apparatus (for example: "Easydiag" developed by SPHERETECH). This device provides a diagnosis of the state of the vehicle, including the proportion of NOx, CO, CO2, HC and O2 contained in the vehicle exhaust. These proportions are expressed in% for CO, CO2 and O2 and in ppm for NOx and HC. The measurements are made through a sampling rod which is introduced into the exhaust pipe. The results are then sent directly to a computer that records the information in real time. Each measure follows a specific protocol, lasting a few minutes. This protocol has been established in order to apply to the analyzed vehicles all the engine speeds to which they can be subjected during their use, for example:

- Slow motion

- Engine cut

- Start-up

- 1200 rpm

- 3200 rpm

- full load rise

- full charge

- back to idle

- engine shutdown

For faultless vehicles, we know the optimum proportion of each of the gases measured at these different speeds. These proportions are the values that the vehicle should display if there were no malfunctions. This is what we call "reference values". In comparison with the measured values, the parts of the motor on which maintenance or corrective action is to be performed can be identified.

Each analysis is recorded automatically in a given format file, for example .xml. These files include all the technical characteristics of the vehicle analyzed as well as possibly the identified defects and the proportions of the gases at time t.

In order to best synthesize the results, and avoid having to manage too many data, 3 engine speeds were chosen from the 9 cited above. These 3 schemes were selected for their representativity of emissions.

These 3 diets are - Slow motion: representative of a traffic in urban area

- 3200 rpm: representative of a motorway traffic

- stopped engine: representative of the emissions generated during the stopping of the vehicle.

Other diets can of course be chosen.

A protocol for determining the emission values of the gases for each of these regimes is established. For example :

Phase 1 (during the idle phase-1200tr / min) with CO2> 1.8% = start of the idle phase - instant T1

Acquire the average value of CO2 during the period T1 + 5s / T1 + 25s

Acquire the average value of CO2 + O2 during the period T1 + 5s / T1 + 25s Acquire the average value of CO during the period T1 + 5s / T1 + 25s

Acquire the average value of HC during the period T1 + 5s / T1 + 25s

Acquire the average value of NOx during the period T1 + 5s / T1 + 25s

Phase 2 - CO2 varies from 0.2% (in + or -) in 1 second = beginning of phase 3200 tr -instant T2

Acquire the average value of CO2 during the period T2 + 5s / T2 + 25s

Acquire the average value of CO2 + O2 during the period T2 + 5s / T2 + 25s Acquire the average value of CO during the period T2 + 5s / T2 + 25s

Acquire the average value of HC during the period T2 + 5s / T2 + 25s

Acquire the max value of HC during the period T2 + 5s / T2 + 55s

Acquire the average value of NOx during the period T2 + 5s / T2 + 25s

Phase 3- Engine stopped

Acquire the value of O2 at instant T3 + 80s

Acquire CO2 value at time T3 + 80s The objective being to measure the impact of a corrective action on the emissions of a vehicle, measurements before and after this action are performed on the vehicles. The measurement results are then sorted, processed, analyzed and then used.

Advantageously, the analysis is based on the use of different cells:

CO-H2 electrochemical cell - 0 to 8000 ppm

Electrochemical cell 02 - 0 to 21%

Electrochemical cell NO - 0 to 5000 ppm

Electrochemical cell NO2 - 0 to 1000 ppm

Electrochemical cell SO2 - 0 to 5000 ppm

Semiconductor cell CH4 - 0 to 10,000 ppm

Opacimeter (m-1).

NH3 cells are also advantageously used. Such cells use amperometric (miniature) sensors that are composed of three electrodes:

- anode: working electrode;

- cathode: counting electrode (in contact with an electrolyte);

- reference electrode.

The gas to be analyzed diffuses through a permeable membrane. Depending on its nature, it is either oxidized at the anode or reduced to the cathode, generating an electrical signal between the two electrodes. This signal is proportional to the concentration of the gas.

The data are recorded in a given format (.xml for example) via a computer and stored in a database.

The footprint is established for different representative engine speeds, different modes of use of a vehicle. In the illustrated examples, the gas distribution, or "atmospheric footprint" is represented by a radar graph. This radar graphic is built by numbers dimensioned as the ratio of a measurement to an initial state or reference value. The atmospheric footprint is obtained by calculating the gas and phase average of the values recorded by the device over a given time interval, during which time the engine and thus the proportion of gases should be stabilized.

There are several reference footprints and several type footprints. The reference values are the average values of the "flawless" vehicles, but distinguishing the "Euro" standards. Depending on the desired representation, the reference values can be:

■ The average values of "fault-free" vehicles with distinction of "Euro" standards, to show the state of the vehicle under study compared to a vehicle of the same standard in "normal" operation

■ The values for the approval of new vehicles, to show the state of the vehicle studied in relation to its new condition,

■ The average values obtained for the vehicle studied before action, to show the state of the studied vehicle after actions,

■ The ratio between the average values of "no fault" vehicles in idle phase and accelerated phase,

■ The average values of the vehicle studied in the accelerated phase.

Reference fingerprints are composed of the aforementioned gases; the value of each gas must correspond to what must be observed under good conditions of admission, combustion and exhaust. They can be in g / min, in% / ppmv or g / km.

Each type of footprint of a rolling vehicle is specific to a large line of anomaly: intake anomaly, combustion anomaly, exhaust anomaly and antipollution treatment anomaly. The identification of anomalies allows the speaker to guide his diagnosis to clarify, to intervene on the vehicle appropriately, to repair malfunctions and reduce pollutant emissions. Analytical implementation

To illustrate this impact simply, the abatement for each of the gases is calculated:

Formula used for the calculation:

Abatement (%) = - (value before - value after) / value before x 100

The sign "-" or "+" of the abatement then indicates the trend. Two other calculations are made:

The first is to represent the difference between the values measured on the vehicle before maintenance and the reference values. This value allows the owner to become aware of the state of his vehicle compared to a vehicle that operates "normally". The formula used is the following:

Ratio (%) = - (reference value - value before) / reference value x 100

The second calculation consists of representing the difference between the values measured on the vehicle after corrective actions and the reference values. Similarly, this calculation has been done to show the owner where his vehicle is in relation to a normal vehicle. Knowing that it is obviously difficult to bring a vehicle to a "normal" operation because of the complexity and all the external parameters involved in the wear of a vehicle. Nevertheless, this difference makes it possible to prove to the owner that the maintenance of his vehicle brings him closer to a "normal" operation.

The calculation is as follows Ratio (%) = - (reference value - value after) / reference value x 100

It is often easier to understand results in a graphical format than in a table format value. A graphical representation of "radar" type is therefore provided, so as to represent the emission state of the vehicle as a whole: it is the atmospheric footprint of the vehicle.

Thus each vehicle has an atmospheric footprint for the idle speed and the 3200tr / min regime and a record of the stopped phase.

The orders of magnitude of the values of the pollutants being very different, it is not possible to place them as such on one and the same scale. Each value is reported to the associated reference values (calculation of the ratio between reference value and measured value).

Calculations made for each gas:

Reference value for radar = 1

Value before maintenance for radar = value before / reference value

Value after maintenance for radar = value after / reference value

FIG. 3 shows an advantageous representation of the characteristics of the vehicle analyzed, the calculated deviations (in%) as well as the radar representation of the atmospheric footprint of the vehicle (adimenal values).

Transformation of the measured data

One of the main difficulties in this approach is to represent in a reliable and intelligible manner the emissions of atmospheric pollutants. Indeed, in the field of air quality, emissions are generally communicated in bulk. Take, for example, car manufacturers who communicate to the general public the emissions of their new vehicles in g / km or the inventories of national emissions published by the CITEPA (Interprofessional Technical Center for Atmospheric Pollution Studies) are also expressed in mass (tons / year). In addition, the inventory of a fleet of vehicles passes by taking into account the evolution of pollutant emissions according to the aging of vehicles. The results we obtain do not allow today to visualize this dimension of the problem, since they can not be compared to any existing data.

The main difficulties lie in metrology

- In the automotive sector, in particular for technical control and for the diagnosis of petrol engines, a relative measurement (in%) of the combustion gases (CO / C02 / HC / 02) is carried out. The ratios between these emissions characterize the possible defect of the vehicle. It should be noted that DIESEL vehicles (the most emitting pollutants implicated by the European authorities) are not subject to these measures.

- In the air quality sector, for measurements of emissions into the air, a measurement is made in real value (by a test bench type IFSTTAR, in g / km). Means of measurement are heavier to implement than in a technical control center.

Each method provides important information but there is no method that responds to both issues simultaneously.

A solution to this obstacle consists in making pressure, temperature and flow measurements simultaneously with the measures mentioned previously.

Indeed, a sequence of equations connecting the mixing ratio (ppmv), the pressure, the temperature and the flow rate makes it possible to change from% or ppmv to a mass value. This sequence of equations is presented below.

Equivalence of units between mg / m ³ and ppmv C _pollutant (mg / Nm) C = _{Polluam bench,} _testing (ppmv) x-

With

- Calculating (mg / Nm3) the measured gross concentration of the pollutant gas in mg / Nm3.

- C _my test bench (ppmv) the measured gross concentration of the pollutant gas in ppmv (parts per million volumetric), measurement of test bench

- M the molar mass of the pollutant gas in g.mol-1. In our case :

M = 28 gmol-1 for CO,

M = 44 g / mol for CO 2,

M = 46 g mol-1 for NO 2,

M = 30 gmol-1 for NO,

M = 12 g.mol-1 for HC

- V the molar volume under normal conditions (22.4 l.mol-1 for perfect gases).

The problem remains because we are not in standardized conditions so V depends on P and T. Indeed, in the case of eco-maintenance, the gases studied are from the exhaust of vehicles to pressure and temperature conditions different from P0 = 1.013.105 Pa and T0 = 273K.

To obtain V, consider that the gases of the muffler behave like perfect gases, we can then apply the law of perfect gases:

PV = nRT With:

P the pressure in pascal (Pa) V the volume in cubic meters (m ³ )

T the temperature in Kelvin (K)

n the quantity of material in mol (mol)

R the constant of perfect gases (R = 8.32 SI)

We are not in the normal conditions of temperature and pressure, but knowing the value of the molar volume V0 under normal conditions, it is possible to determine the value of the molar volume under other conditions of pressure P and temperature T. The product nR (n = 1 mol) being a constant, it suffices to write:

P x V, m P _n * V, P _ft x V _n x T

which gives: V. =

TT, P x T ₀

With:

V0 = 22.4.10-3 m3.mol-1.

T0 = 273 ° K

P0 = 1.013.105 Pa

The concentration in grams can therefore be determined as a function of the temperature and the pressure of the measured gases. These measurements will determine the molar volume under pressure and exhaust temperature conditions.

The equation becomes:

M x T x P

C _p oiiuant (mg Nm ³ ) = C ^^ ^ _g Cppmv) x ⁰

* η 0 X ~ * _n 0 X 1 Example:

Calculations made for NO with:

A value read from 212ppmv

A temperature of 200 ° C (or 473 ° K) and a T0 of 273 ° K a PO of 1.013 hPa

A molar volume of 22.4.10-3 m3.mol-1

M x T x D 30 x 273 x P

C _pollutant (mg / Nm ³ ) = C _pollutant _ _easydlag (ppmv) x = 212 x _{1> 013 χ 473 χ 22> 4} If P1 = 0.980 hPa, then C (NO) = 158g / l

If P2 = 1, 100 hPa then C (NO) = 178g / l

The measurement of the flow (in l / minute) allows to deduce the amount of pollutant in g / minute.

It is therefore, despite a difficult physical context (particles and clogging sensors) to measure the pressure, T ° and flow in addition to the chemical measurements made. Methodologies to obtain complementary measures

As we explained in the previous paragraph, it is necessary to measure the pressure and the temperature. In general for these measurements, several methods are possible. They are summarized and discussed below.

The flow measurement will take place in the muffler and the pressure and volume measurements will take place closer to the concentration measurement. The pressure and volume sensors must therefore meet congestion conditions corresponding to the need. a) Pressure measurement:

A solid deformation sensor is used in case of need for an indication or a direct recording of the differential pressure and where a filling fluid will be harmful for the process. Under the action of pressure, a solid deforms and the amplitude of the deformation is sensed. In particular, there are piezoelectric pressure gauges which have the advantage to be of small size, to have a fast response time at an acceptable cost.

In general, the sensor provides an analog output that should be connected to a computer. b) Temperature measurement

The measurement of temperature by a thermocouple is the most conventional. It is a measure that is easy to implement and cheap. c) Flow measurement by dynamic pressure measurement

To measure the flow, the pitot tube appears as the easiest technique to implement. The use of a PITOT tube involves measuring the pressure at different locations inside the exhaust. One of the tubes measures the stop pressure (or dynamic pressure) at a point in the flow. The second tube measures only the static pressure, usually on the pipe wall. The differential pressure measured on either side of the PITOT tube is transmitted to a sensor making it possible to transform the electrical signal into an exploitable analogue signal. We can then record, visualize in real time, and exploit all the measurements from the installation and thus make a complete, exhaustive and transparent diagnosis to the technician and the consumer.

The latter offering an electrical signal proportional to the square of the speed, the computer must perform the calculation to obtain a signal proportional to the flow.

Figure 8 shows a variant of a reference footprint in which the shaded area represents an example of a preferred range in which the values are considered acceptable. Beyond this zone, the corresponding values are considered ineligible.

In another variant, the method is completed by the following steps: To evaluate the necessity for a vehicle to be controlled or not (for example: gas diagnosis), on the basis of several criteria, the evolution of the curve representative of the variation of the consumption (L / 100km) of the vehicle studied according to time and a consumption ratio corresponding to the ratio between the consumption in L / 100km of the vehicle studied compared to the consumption in theoretical L / 100km of the same new vehicle or a C02 ratio corresponding to the ratio of emissions in g / km of CO2 of the vehicle studied and the emissions in g / km of theoretical CO2 of the same new vehicle.

Track consumption (quantity in L of fuel), milestones in time before and after corrective actions to assess the real gains in fuel consumption, fuel costs and pollutant emissions brought by these corrective actions.

The acquisition of the data can be performed via a file exchange interface and recording / storage of data in a server / database. The data may be derived from, for example, tracking of fuel supplier maps or other means of monitoring.

The figures and their descriptions made above illustrate the invention rather than limiting it. In particular, the invention and its various variants have just been described in connection with a particular example having a fingerprint shaped radar or spider web.

Nevertheless, it is obvious to a person skilled in the art that the invention may be extended to other embodiments in which, in variants, one or more other types of imprints and / or method of calculation are provided for obtaining fingerprints.

The reference signs in the claims are not limiting in nature. The verbs "understand" and "include" do not exclude the presence of elements other than those listed in the claims. The word "a" preceding an element does not exclude the presence of a plurality of such elements.

Claims

A method for controlling and reducing vehicle emissions comprising the steps of:

• using a vehicle exhaust gas test probe, detecting the gases emitted by the vehicle during an engine test under given operating conditions (10);

• determine the actual distribution of the gases emitted by the vehicle on which the measurements are made (30);

• compare the actual distribution obtained with a typical distribution corresponding to the vehicle on which the gases are measured (40);

• on the basis of deviations measured between the two distributions (50), determine a corrective action to be performed on the vehicle in order to reduce the polluting emissions of the latter (60).

The method according to claim 1, wherein the effective distribution comprises relative value emission data measured on at least the following gases: CO, CO2, NO, NO2, NOx (calculated), HC and NH3, and preferably particles such as PM10 and / or PM2.5.

3. Method according to one of claims 1 or 2, wherein the distribution by gas is established on a multi-axis polygon graph whose number of axes corresponds to the number of gases.

4. The method of claim 3, wherein the multi-axis graph is in the form of a pentagon.

5. The method of claim 4, wherein the pentagon indicates the following gases, angularly distributed around the polygon in the following order, in the clockwise direction: CO2 + O2, CO2, CO, HC, NOx.

6. Method according to one of the preceding claims, further comprising a step of measuring the flow of the vehicle exhaust gas.

7. Method according to one of the preceding claims, further comprising the steps of:

• determining, for a reference period, the corresponding mass of gas emitted by the vehicle for at least one gas and preferably the following gases or pollutants 02, CO, CO2, NO, NO2, NOx (calculated), HC, NH3 and particles (PM10, PM2.5).

8. Method according to one of the preceding claims, further comprising a step of performing a new control of the exhaust gas after the corrective action has been performed on the vehicle.

9. Method according to one of claims 6 to 8, wherein the flow measurement comprises the steps of:

• using a temperature sensor, measure the average temperature of the exhaust gases;

• using a pressure sensor, measure the average pressure of the exhaust gas;

• determine the corresponding gas flow.

10. Method according to one of the preceding claims, further comprising the steps of:

• performing a data pool corresponding to a time (T1) before and a time (T2) after the corrective action for a set of vehicles for which the gas analysis measurements are made (110);

• make a comparison between the global emissions after correction and the global emissions potentially emitted if the corrective actions had not been carried out.

The method of claim 10, further comprising the steps of:

• compare overall emission data for the set of vehicles with global reference data (120);

• Based on measured discrepancies between the overall baseline data and the actual data compiled, determine an overall corrective action to be performed on at least a portion of the vehicles to reduce overall pollutant emissions (130).