WO2009004216A2

WO2009004216A2 - Method for a vehicle fuel circuit

Info

Publication number: WO2009004216A2
Application number: PCT/FR2008/051045
Authority: WO
Inventors: Michaël HADDAD; Karim Mokaddem; Orsolya Sadik-Rozsnyai
Original assignee: Peugeot Citroën Automobiles SA
Priority date: 2007-06-13
Filing date: 2008-06-12
Publication date: 2009-01-08
Also published as: EP2156177A2; FR2917496B1; FR2917496A1; WO2009004216A3

Abstract

The present invention relates to a fuel circuit of an automotive vehicle comprising a light source that emits over a wavelength between 350 and 450 nm and a detector that makes it possible to measure the dilution of the absorption when a fuel comprising an alcohol fraction greater than 10% is diluted by a petrol.

Description

Fuel system of a vehicle and vehicle having such a fuel system

The present invention claims the priority of the French application 0755734 filed on June 13, 2007 whose content (description, claims and drawings) is incorporated herein by reference.

The present invention relates to the identification of the basic characteristics of a motor fuel, in particular the discrimination at the vehicle level between conventional fuels of the "gasoline" type and ethanol fuels, such as for example the so-called E85 fuel, consisting of 85% ethanol and 15% ordinary gasoline.

The use of alternative fuels, particularly highly ethanol fuels to replace petroleum fuels is nowadays strongly favored by the public authorities. However, if an engine is designed to work with a conventional fuel of petroleum origin such as EuroSuper fuel, while the full is performed with a highly ethanol fuel, it is observed a serious deterioration of driving pleasure, even an impossibility to start, accompanied by a strong emission of harmful gases in the exhaust. Furthermore, the alcohol is highly corrosive, which causes premature aging of unsuitable parts, such as the tank and the electronic components thereof. It would therefore be useful to have keys to avoid fuel errors.

A similar problem is of course with the marketing in gas stations both diesel (also commonly called diesel) and gasoline, modern diesel engines are equipped with injection systems that are heavily degraded in case use of an unsuitable fuel that in extreme cases can even lead to engine failure. In this case, it is well known that the basic solution consisted in equipping all the fuel dispensing pumps with a mechanical keying device which forbids the filling at the pump of the tank of a gasoline engine with diesel, with a section of the diesel pump gun is too wide to enter the tank of a gasoline engine. This standardization at the level of the dispensing pumps has of course supposed a corresponding standardization at the level of the vehicles.

However, it is not expected to generalize this practice at the level of biofuels, if only because of its cost which could only hinder the generalization of the supply of fuel and ethanol on the other hand, of its relative ineffectiveness, a number of motorists demonstrating every day that with a little skill, it is possible to make an error - error that it would be all the easier to commit an intermediate diameter between gasoline and diesel would for example be chosen for ethanol fuel. Under these conditions, it appears desirable to have at the vehicle level means to differentiate quickly and safely a fuel ethanol from a conventional fuel.

The problem of identifying the fuel remains when the vehicle is equipped with a so-called "FLEXFUEL" engine, that is to say capable of operating with a conventional fuel of petroleum origin or a fuel comprising more or less significant proportions of ethanol, such as E85 fuel marketed especially in Europe and the United States, mainly based on products derived from the agricultural industry. Indeed, if these engines are designed to withstand the corrosive nature of alcohol, the fact remains that many engine parameters must be adapted, which is typically done by choosing a different engine control map, the choice of cartography assuming the identification of the fuel. Note also that in this case, it is not only a question of type yes / no, because not only fuels more or less rich in ethanol can be marketed according to places but more and more importantly, motorist performs a more or less complete filling of a tank most often not empty, so that the tank contains a fuel whose ethanol fraction can be between virtually all values from 0 to 100%.

It is therefore necessary to have a safe means, embedded on the vehicle, to discriminate between a conventional fuel and a fuel ethanol, to be alerted to the motorist as long as there is still time (any engine can accept a less than 10% if the alert is sufficiently early, in the case of engine not designed for highly ethanol fuels, the error can be made harmless simply by performing a filling supplement with a conventional gasoline. For FLEXFUEL engines, the detection makes it possible to better adapt the engine control and optimize the engine performance.

On FLEXFUEL vehicles currently marketed, this adaptation of the engine control is performed a posteriori, from the information given by the oxygen sensor present in the exhaust line, in other words by combustion analysis. The major drawback of this technology is that the information is not available at the start of the engine (although strategies to minimize this disadvantage are employed, starting with the assumption that the fuel is identical to the fuel present in the tank before the last stop of the engine).

From EP 494734, it is known to operate an optical measurement, for example at the reservoir, based on the measurement of the absorption of light on at least two wavelengths in the infrared for which absorption by a hydroxyl compound (ethanol or methanol) is maximal, and comparing the measurement of the relative absorbance with respect to a reference fuel.

The same principle is found in the publication WO 9003565 which teaches the determination of the alcohol concentration in a fuel alcohol mixture by means of a pair of sensitive elements which detect the absorption on two bands. The first band corresponds to wavelengths for which the absorption by the alcohol is maximum, while the absorption by the fuel is essentially zero. The second band is chosen such that the fuel and the alcohol then have a substantially identical absorption behavior. The signals representative of the two sensors are rationalized to form a signal representative of the alcohol concentration.

In both cases, the measure is derived from the consideration that even if oxygenated assets are present in the conventional fuel, they are in the form of ethers (ETBE or MTBE type), and therefore the presence of a hydroxyl group -OH associated with a carbon chain is well characteristic of fuels alcoholic (and therefore in particular ethanol fuels). The radical -OH can be identified by spectroscopy by its absorption peaks in the near infrared.

The major disadvantage of these devices is however a relative lack of robustness, and the fact that they can not be used as polarizers, that is to say as means for detecting an attempt to fill the tank with an unsuitable fuel. Indeed, it is not easy to make an accurate diagnosis because at these wavelengths, the contribution of alcohol to the absorption of light is partly or even totally confused with the contributions of characteristic chemical groups hydrocarbons (-CH- or -CH2- for example) and only a complex signal processing (linear regression to the least square, for example) allows to isolate the contribution of ethanol. In fact, even if these techniques have been presented as being able to be implanted in vehicles, their field of application has remained for nearly 20 years in the field of the laboratory.

The present invention proposes a variant of these techniques based on spectrometric measurements consisting in observing the decrease in the absorption of a blue light when the gasoline is diluted by the addition of an alcohol (or at least one strongly ethanol fuel).

By blue light, it is understood a wavelength between about 350 nm and about 450 nm, preferably between 380 and 420 nm, more preferably about 400 nm. Advantageously, the light source is not necessarily monochromatic and may very well be constituted by a relatively inexpensive source such as a blue light emitting diode (LED), with a broad emission spectrum compared for example with a laser source - and therefore a lot less expensive and more robust. For signal analysis, a simple phototransistor may suffice.

So reverse the problem allows to use only one sensor and a single wavelength - or light band. Indeed, if the absorption by alcohol is very dependent on the temperature, this is not the case of the absorption behavior of the gasoline which can, at least in the range of ambient temperatures likely to be encountered during filling of the tank, be considered as essentially independent of the temperature. Thus, it is therefore much more relevant to place the opposite in a region of the spectrum or it is the essence that absorbs light and not ethanol. This is much simpler since we can see with the naked eye that ethanol is a transparent liquid. In the ultraviolet blue between 350 and 450 nm, hydrocarbons contained in gasoline strongly absorb light while ethanol not at all. It therefore becomes easy to measure the light absorption of a single LED in the region around 400 nm without the need to include a complex signal processing or referencing (except possibly to guard against the aging of components). The ethanol concentration of the mixture is simply proportional to the intensity of light passing through the fuel sample and measured across a phototransistor. The higher the ethanol concentration, the more the mixture becomes transparent to blue light.

In a simple keying version, it is simply important to detect if the fuel output of the gun is of the gasoline type or E85. The advantage of an optical method is its instantaneous nature, which makes it possible to alert the driver immediately, for example when a volume of only a few decilitres has been introduced into the tank, knowing that as long as the ethanol fraction is less than about 10%, ie at least an introduced volume of more than 5 liters for a 50 liter tank, the driving pleasure is not significantly modified and the risks of degradation are minimal.

In this "keying" version, the fuel identification system is supplemented by means for warning the motorist of the fuel error, for example by triggering an audible alarm inviting him to stop immediately filling the tank and / or means to block the engine start to prevent the destruction of sensitive elements, especially if the alarm was not taken into account in a short time.

For a FLEXFUEL engine, the information on the nature of the fuel does not need to be relayed to the driver - except possibly through a logbook intended in particular to monitor the evolution of consumption in fuel. On the other hand, this information makes it possible to calculate the exact nature of the mixture knowing on the one hand that the introduced fuel is in a given country either E85 is a gasoline and the volume of fuel introduced is known by comparing the fuel level before and after the pump.

The absorption of light can be observed in transmission, for example by placing the light source and the sensor facing each other along a diameter of the duct connecting the fuel door of the vehicle to the tank. It may also be in reflection, in which case source and sensor may be arranged in close proximity to one another.

In a particularly preferred embodiment of the invention, the measurement is essentially by diffusion and absorption, preferred method because compatible with a fluid having a high degree of turbulence, as is often the case with a fuel just out a pump.

Overall, the technique of the invention is extremely robust and very inexpensive, and perfectly capable of providing information on a fuel error that the motorist can correct simply by continuing to fill the tank with a appropriate fuel or to allow the modification of the engine operating parameters before the vehicle is restarted, thus ensuring good driving pleasure and optimum performance in reducing pollutant emissions.

The invention will be better understood on reading the description which follows, given solely by way of example and with reference to the appended drawings, among which:

[0024] Figure 1 is a diagram of the fuel system of a motor vehicle, from the fuel door to the tank;

Figure 2 is a circuit diagram similar to Figure 2, in a transmission mounting;

Figure 3 is a circuit diagram showing a possible implantation of the sensor, in a mounting in reflection;

FIG. 4 is a diagram illustrating the preferred embodiment of the invention, with a measurement according to the diffusion / absorption mode; and [0028] Figure 5 is a block diagram showing how the measurement according to the invention can be used to determine the alcohol concentration of the fuel present in the vehicle tank.

As illustrated in Figure 1, the fuel supply circuit essentially comprises a mouth 1, terminated by a cap and / or a hatch, a conduit 2 and a reservoir 3. On modern vehicles, the reservoir is typically placed under the floor of the vehicle, so that the duct 2 comprises a first portion 4 substantially vertical and a second substantially horizontal portion 5, these two parts being joined by a bend 6.

In this Figure 1, there is surrounded three preferred points of implantation of a sensor according to the invention, encircled in this figure and located respectively at the point of entry 7 into the reservoir, at the elbow 8 and at the hatch 9. Note that these points are soldering areas which allows to simply insert the transmitter and the detector at the time of manufacture of the conduit. The closer we get to the tank, the better the fuel flow is homogenized which is favorable to the measurement. However, a relatively downstream measurement of the fuel system is accomplished while a significant amount of fuel has been admitted into the circuit, which is not desired in the event of a simple keying application; a measurement upstream, just at the hatch, to alert the driver as soon as possible.

According to the invention, the fuel is identified by measuring the dilution effect of the absorption of a blue light when a gasoline is diluted with alcohol. Note that the absorption of light by gasoline is very strong for any light whose wavelength is between about 300 nm and about 450 nm, which makes it possible to use any light source emitting in the " blue ", especially a light-emitting diode as found for multiple commercial applications and which emit in a more or less wide spectrum. Of course, a monochromatic source, in particular a laser source, can also be used. The high absorption also makes it possible to use only relatively small thicknesses, typically of the order of 5 to 30 mm, whereas for measurements in the infrared, an optical path of at least 100 mm is necessary. The detection of the light beam can be carried out by any means suitable for detecting unabsorbed light. A phototransistor is sufficient and will preferably be used because of its low cost but other means, in particular a photodiode or a joulemeter may also be used.

In all cases, the light source and the detector may preferably placed in a point of the duct requiring anyway a weld.

As previously indicated, the blue light is essentially absorbed in the gasoline while it is transmitted substantially unabsorbed in the alcohol. In other words, the measurement can be considered as an "all or nothing" measurement, requiring only a basic electronic circuit to transmit for example the "detected gasoline" or "detected E85" information.

The power supply circuit of the light source is preferably closed as soon as the fuel door is open. More preferably, the light is emitted in the form of pulses rather than in a continuous manner, which makes it possible to differentiate an almost zero absorption (the conduit contains only air), a very slight absorption (the conduit is filled with gasoline and not a strongly ethanol fuel).

In a first variant of the invention, the measurement is performed in transmission as shown in Figure 2. The transmitter 10 and the detector 1 1 are vis-à-vis for example diametrically opposed or possibly slightly offset and are separated by a fuel thickness corresponding to the diameter of the fuel pipe. In this assembly, the light passes through the fuel once. This single passage is not very favorable from the point of view of the sensitivity of the device but allows space transmitter and detector.

According to a second variant of the invention, illustrated with reference to FIG. 3, the measurement is carried out in reflection. In this variant, it is necessary to have a reflecting surface 12 facing the light source, for example consisting of a metal or dielectric mirror or even more simply a simple white surface. The signal coming from the transmitter 10 is reflected by this reflecting surface and returns to the detector 11 positioned on the same side as the transmitter (the mirror possibly being placed in such a way that the beam light is slightly deviated, especially in the case of a light source emitting a very fine light brush and a detector not superimposed on the source. Note that when using a light emitting diode, the dispersion of the light beam is sufficient to allow a slight offset between the emitting source and the detector.

As the signal travels back and forth, in this variant, the sensitivity is increased but the distance between the transmitter and the reflective wall must not be too great.

According to a third variant of the invention, applicable at a point of the duct where the fuel drives a relatively large amount of air, in other words near the fuel filler, just under the fuel pump gun, the combined principle of diffusion and absorption is used. Indeed the continuous air in the fuel will cause a significant diffusion of the signal.

As illustrated by means of FIG. 4, this phenomenon can be exploited by placing the detector on the same side as the transmitter, at a distance not exceeding, for example, 90 ° of an arc of a circle, and preferably between about 10 ° and about 60 °. In this case, it is not necessary to provide a reflective surface.

As the duct 4 is filled with air, the light signal does not reach the detector. From the moment when a fuel jet 12 is introduced, a mixture of air and fuel as at the exit of a fuel gun, the air 13 contained in the fuel causes a significant diffusion of the light signal, a part of which then arrives. to the detector. If the fuel is of the ethanol type this part of the signal is diffused without being absorbed and therefore a high level signal is detected. If the fuel is mainly gasoline based, the signal absorption is very important and therefore only a weak signal is detected.

This variant of the invention is particularly suitable for very early detection of the nature of the fuel because it is all the more effective that the fuel has not had time to decant, in other words that the measurement is carried out just at the end of the fuel pump gun, when it is fully inserted into the pipe. This information can be processed in different ways. For example, it may be associated with a buzzer and / or visual (activation of flashing lights of emergency alarm) and a prohibition of starting. Mixed strategies can advantageously be used. For example, if the user reacts immediately to the warning signal and stops filling the tank, then continues it with a suitable fuel, it can be estimated that the amount of "bad" fuel is minimal and not harmful.

If on the other hand, the user continues the filling operation or stops without continuing the filling with a "good" fuel (according to the information communicated by the gauge), then the restart of the vehicle can be not allowed.

In any case, the interface with the computer for data processing and the application of the user's warning strategy is facilitated because of the presence of a communication beam for the user. fuel gauge information nearby.

For FLEXFUEL vehicles, the same system can be envisaged which allows not to differentiate the fuel circuits of "ordinary" vehicles or "FLEXFUEL vehicles". Indeed, for these vehicles, it is useless to look for relatively sophisticated information such as the concentration of ethanol in the fuel dispensed by the pump but simply to discriminate between a gasoline or a fuel rich in ethanol.

In many countries, the commercial offer is indeed a fuel with 85% ethanol. As modern vehicles are equipped with devices for measuring the fuel level in the tank, which makes it possible to estimate relatively accurately the amount of fuel available, typically displayed via an interface associated with the dashboard through which are displayed various related information such as the estimated range, the average consumption on the last trips, etc.

As illustrated in the block diagram of FIG. 5, if there is a first estimate of the nature of the mixture, defined for example by the concentration of alcohol Ci, noting Vi the volume of fuel in the tank before filling and Go the volume after filling, if the full is carried out with fuel type E85, the alcohol concentration after this full is given by the formula:

_ Fz * Cz + (Fa - Fz) * 0.85 Va

In other words, the only constraint is to know the alcohol concentration of the fuel used by the manufacturer for the very first full of the vehicle.

Advantageously, the above formula may be parameterized so as to replace the value of 85%, common in countries regularly exposed to freezing, by a value of for example 1, if "pure" ethanol is marketed in the country concerned, as for example in Brazil.

The alcohol concentration of the mixture present in the reservoir thus estimated makes it possible to select an engine control map adapted to the available mixture, emphasizing that most often, an approximation (for example 10 to 10%) is very sufficient for allow a good adaptation of the motor parameters.

For these FLEXFUEL vehicles, it is also possible to carry out a direct measurement, the voltage across the phototransistor being proportional to the ethanol concentration of the fuel mixture. This measurement is then directly used to select an engine control map adapted to the fuel present in the vehicle.

In this case, the detector can be advantageously not located near the fuel filler but rather or at the fuel pump pump gauge module (in the tank) or in the engine fuel system, or by example just at the entrance of the injection rail. Positioning the sensor at the inlet of the injection rail eliminates the need to take into account the fuel present in the line between the tank (usually located in the rear seats of a vehicle) and the engine (usually at the before).

Claims

claims

1. A method for identifying the fuel present in a tank of a motor vehicle comprising the detection of the absorption of a light beam emitted by a light source whose wavelength is between 350 nm and 450 nm due to diluting a gasoline-type fuel by a fuel having a higher alcohol fraction 10 ^"%.

2. Method according to claim 1, characterized in that the light source emits at a wavelength of between about 380 and about 420 nm.

3. Method according to claim 1 or claim 2, characterized in that said detection is provided in the form of binary information discriminating between a gasoline or a highly ethanol fuel.

4. Method according to claim 3, characterized in that it further comprises the evaluation of the volume of fuel present before and after a filling operation of the tank, means for memorizing the concentration of alcohol in the fuel before filling and means for evaluating the alcohol concentration after the fuel, taking into account information on the nature of the fuel.

5. Method according to any one of claims 1 to 4, characterized in that the detection is obtained by means of a detector of the photodiode type, phototransistor or joulemeter.

6. Method according to any one of claims 1 to 5, characterized in that the light source is a light emitting diode.

7. Method according to any one of claims 1 to 6, characterized in that the light source emits drive.

8. Method according to any one of claims 1 to 7, characterized in that the detection is obtained by means of a detector placed opposite the transmitter.

9. Method according to any one of claims 1 to 7, characterized in that the detection is obtained by means of a detector arranged so as to receive a light signal reflected by a reflective surface placed opposite the light source.

10. Method according to any one of claims 1 to 9, characterized in that the detection is obtained by means of a detector, placed in a point where the fuel is cloudy, at an angular distance from the light source of between 10 ° and 90 °, so that the signal diffused by air trapped in the fuel is transmitted, being more or less absorbed depending on the nature of the fuel.

Method according to one of Claims 1 to 10, characterized in that the detection is carried out at the inlet of the injection rail.

12. Method according to any one of claims 1 to 10, characterized in that the detection is performed at the fuel pump inlet of the pump gauge module of the fuel tank of the vehicle.

13. Method according to any one of claims 1 to 10, characterized in that the detection is carried out near the fuel filler of the vehicle.

14. A method according to any one of the preceding claims comprising the emission of audible or visual warning signals if the fuel used to fill the tank is not adapted to the engine of the vehicle.

15. A method according to any one of the preceding claims including the blocking of the restart of the vehicle if the fuel used to fill the tank is not adapted to the vehicle engine.

16. The method as claimed in any one of the preceding claims, in which the detection is carried out by means of a phototransistor type detector, characterized in that the measurement of the voltage across the phototransistor is used as a direct measurement of the concentration of the phototransistor. ethanol in the fuel present in the tank, this measurement being used to select an engine control map adapted to the fuel present in the vehicle