Locating a fuel leak in a fuel system

Abstract

The invention relates to a method for locating a fuel leak in a pressurised fuel system (1) for a vehicle provided with a combustion engine (2), the method comprising the following steps: - wherein the system (1) comprises a first container (4) and a second container (5) that are openly connected to each other, carrying out a first test to determine the presence or absence of a fuel leak in the system (1) comprising the first container (4) and the second container (5); - when the presence of a fuel leak is determined upon completion of the first test (100): * closing the connection between the first container (4) and the second container (5) so as to isolate the two containers from one another; * carrying out a second test for determining the presence or absence of a fuel leak in the first container (4); * if the presence of a fuel leak is detected upon completion of the second test, concluding that a fuel leak is located in the first container (4) or, if the absence of a fuel leak is detected upon completion of the second test, concluding that a fuel leak is located in the second container (5).

Description

Locating a fuel leak in a fuel system

[0001] The invention relates to the location of a fuel leak in a vehicle fuel system, in particular after stopping a thermal engine of the vehicle. It relates more particularly to a passive location method, i.e. a method which does not require the generation of suction or vacuuming of the fuel system, nor any other mechanical operation on the containers.

[0002] Already known in the prior art, in particular from document EP3409936, is a method for passively determining the presence or absence of a fuel leak in a pressurized fuel system of a vehicle equipped with a heat engine. This method is implemented after stopping the heat engine. It comprises steps of measuring pressures and temperatures at certain times during a period of time, then steps of calculating a first maximum temperature difference between these times. If this first temperature difference is greater than a predetermined temperature difference threshold, the method comprises a step of calculating a pressure difference between the two corresponding times. If this pressure difference is less than a predetermined pressure difference threshold, the method concludes that there is a fuel leak in the fuel system.

[0003] A disadvantage of this method is that, if a fuel leak is found, it does not allow the fuel leak to be located in the system. Therefore, to remedy the fuel leak, it is necessary to dismantle or even replace the entire system, which is complex and expensive.

[0004] US11542896, CN113389 and KR20170131610 teach respective methods of detecting leaks in a fuel system.

[0005] The invention aims in particular to enable the location of a fuel leak in a fuel system, whether the fuel is in the liquid and / or gaseous state, using a passive method.

[0006] To this end, the invention relates to a method for locating a fuel leak in a pressurized fuel system for a vehicle equipped with a heat engine, comprising the following steps:

[0007] - the system comprising a first container and a second container openly connected to each other, first passive test for determining the presence or absence of a fuel leak in said system comprising the first and second containers;

[0008] - when the presence of a fuel leak is determined following the first passive test:

[0009] * closing the connection between the first and second container so as to isolate the two containers from each other;

[0010] * second passive test to determine the presence or absence of a fuel leak in the first container;

[0011] * when the presence of a fuel leak is detected at the end of the second passive test, conclusion of the location of a fuel leak in the first container, or when the absence of a fuel leak is detected at the end of the second passive test, conclusion of the location of a fuel leak in the second container, the first and second passive tests being passive in that they do not require the generation of suction or vacuuming of the fuel system or any other mechanical operation on the first and second containers.

[0012] Thus, thanks to the second passive test carried out once the first and second containers are isolated from each other, the fuel leak detected at the end of the first passive test can be located as being either in the first container or in the second container. This method therefore makes it possible to locate the fuel leak, either in the first container or in the second, simply by closing a connection and carrying out a second passive fuel leak detection test. It is therefore particularly simple to implement. It only requires a test to determine the presence or absence of a fuel leak in a fuel system to be carried out in a container and a means of closing a connection between the container and another container in the system.These two elements, the passive determination test, as well as the means of closing the connection, can already be existing in a vehicle, so that the localization process is simple and inexpensive to implement. Thus, only the faulty container is dismantled and / or replaced to repair the fuel leak, rather than the entire two containers.

[0013] The term "fuel system" means any device incorporated into a vehicle equipped with a heat engine whose function is to store, purify, measure or transport fuel intended to supply the heat engine. A fuel system comprises at least a fuel tank and a fuel supply line to the heat engine. It may also include one or more of the following accessories: fuel tank vent valve and line, filler pipe, canister, fuel filter, fuel pump, fuel tank gauge, electrical connector, closing cap as well as any component, in general, through which fuel passes in liquid and / or gaseous state, for example, a fuel vapor circulation pipe.

[0014] The vehicle equipped with a thermal engine can in particular be a hybrid vehicle.

[0015] Other optional features follow, taken alone or in combination.

[0016] Preferably, the first passive test includes the following steps:

[0017] - after stopping the vehicle's thermal engine, measurements, at different predetermined times over a period of time, of respective pressure values ​​in the system;

[0018] - determination, among the instants, of the two instants whose respective pressure values ​​are the furthest from each other;

[0019] - when an absolute value of pressure difference between these two values ​​is less than or equal to a predetermined pressure difference threshold, conclusion of the presence of fuel leakage in the system and stopping of the process.

[0020] Thus, it is sufficient to carry out pressure measurements over a period of time and to determine the maximum pressure difference, i.e. between the lowest pressure measured and the highest pressure measured during this period of time, to conclude on the presence of a fuel leak. This method is based on the observation that, below a predetermined pressure difference threshold, i.e. for a pressure change over time that is particularly low with respect to the period of time considered, it can be reliably concluded that there is a fuel leak in the fuel system, without having to take temperatures into account. This method is therefore particularly simple to implement.

[0021] It is specified that if there is no conclusion on the presence of a fuel leak at the end of these steps, it is not necessarily concluded that there is no fuel leak. Other steps can therefore be implemented to look for one or other of these conclusions.

[0022] We understand that an "instant" is a point in a period of time associated with a pressure in the fuel system.

[0023] Advantageously, the first and second passive tests for determining the presence or absence of a fuel leak comprise steps of:

[0024] - measurement, at different predetermined times of the first and second respective time periods, of pressure and temperature values ​​in the first container of the system;

[0025] - comparison of at least one of the values ​​to a predetermined threshold.

[0026] Thus, the test implemented twice to determine the presence or absence of a fuel leak includes simple steps of measuring temperatures and pressures in the container(s) and comparing them to thresholds.

[0027] Preferably, the first passive test is implemented following a shutdown of a thermal engine of the vehicle and for a predetermined period of time, preferably at least four hours, in particular at least six hours.

[0028] Thus, the invention is particularly suited to compliance with the American standard called "CARB" (for "California Air Resources Board"), which requires a six-hour observation period.

[0029] Advantageously, the second passive test is implemented immediately after the end of the first passive test when the presence of a fuel leak has been detected at the end of this first passive test.

[0030] So, if a fuel leak is detected after the first test, the connection between the two containers is immediately closed and the second test begins to locate this fuel leak.

[0031] Preferably, the second passive test is continued for a predetermined period of time, preferably at least two hours.

[0032] Thus, the second test is economical since it is stopped in a predetermined manner.

[0033] Alternatively, the second passive test is continued until the vehicle equipped with a thermal engine is restarted.

[0034] The second test is less economical here, but since it lasts until the vehicle is restarted, it is likely to include more measurements taken, since the time period can be extended. It therefore increases the probability of locating the fuel leak, since the more measurements there are and the longer the time period, the more likely a fuel leak is to be detected.

[0035] Alternatively, the shutdown of the thermal engine being a first shutdown, the second passive test is implemented after a second shutdown of the thermal engine itself following a restart of the thermal engine following the first passive test, the second passive test being continued for a predetermined period of time, preferably at least six hours.

[0036] Thus, the second test only begins at the "next cycle", i.e. after another shutdown of the combustion engine. This alternative is therefore even more economical than the two previous ones, and requires more time to locate the fuel leak since it is necessary to wait for this new cycle. However, in this alternative the second test is more efficient than in the two previous ones and as efficient as the first test, since it is carried out under the same conditions as the first test: it begins as soon as the combustion engine is stopped and can last a sufficiently long time, for example six hours.

[0037] Advantageously, the method comprises, in the absence of a conclusion on the location of the fuel leak at the end of the second passive test, after stopping the heat engine itself following a restart of the heat engine following the second test, the following steps:

[0038] - closing the connection between the first and second containers of the system so as to isolate the two containers from each other;

[0039] - third passive test for determining the absence or presence of a fuel leak in the first container of the system, continued for a predetermined period of time, preferably at least six hours, the third test being passive in that it does not require generation of suction or evacuation of the fuel system or other mechanical operation on the first and second containers.

[0040] Thus, if the fuel leak has not been located at the end of the second test, and while the vehicle has resumed driving, this second test is repeated on the following cycle, this is the "third test". This ensures that the fuel leak is located even if it takes time, rather than starting the detection of a fuel leak from scratch with the first test.

[0041] Preferably, the first container of the system is a fuel tank and the second container is a canister, the opening and closing of the connection being operated by a valve.

[0042] Thus, the first test makes it possible to detect a fuel leak in this subassembly formed by the tank and the canister, and the second test makes it possible to locate the fuel leak either in the tank or in the canister.

[0043] The invention also provides a data processing device comprising a processor adapted to the steps of the method described above, for implementing said steps of this method.

[0044] This device is in particular a control unit integrated into the vehicle.

[0045] The invention also provides a fuel system for a vehicle equipped with a heat engine comprising:

[0046] - a first and a second container connected to each other;

[0047] - a valve for opening and closing the connection between the first and second container;

[0048] - a device as described above for implementing the steps of the method described above.

[0049] The valve can be a standard isolation valve, for example of the "FTIV" type (for "fuel tank isolation valve") if the two containers are a tank and a canister, or one stage of a double valve including another stage to open and close the connection between the second container and the atmosphere.

[0050] The invention also provides a vehicle equipped with a heat engine comprising a fuel system as described above.

[0051] The invention also provides a computer program comprising instructions which, when the program is executed by a computer, cause the latter to implement the steps of the method described above.

[0052] Also provided according to the invention is a computer-readable recording medium comprising instructions which, when executed by a computer, cause the latter to implement the steps of the method described above. Brief description of the figures

[0053] The invention will be better understood on reading the following description, given solely by way of example and with reference to the appended drawings in which:

[0054] is a schematic view of a fuel system according to the invention;

[0055] is a schematic view of the system in a different configuration

[0056] is a diagram of a fuel leak detection method; and

[0057] is a diagram of a fuel leak location method according to the invention; Detailed description

[0058] Figures 1 and 2 show an embodiment of a fuel system 1 of the invention. This fuel system 1 is a pressurized fuel system for a thermal engine 2 of a vehicle. It is integrated into a vehicle in a manner not illustrated. The vehicle may or may not be hybrid. This system comprises a data processing device 3, a fuel tank 4, a canister 5 and a double valve 6.

[0059] The data processing device 3 comprises a processor 7 adapted to the steps of the methods 100 and 400 described below to implement the steps of these methods 100 and 400. The term "adapted" means that the processor 7 is particularly configured to implement these methods. The data processing device 3 further comprises a computer-readable recording medium 8 comprising instructions which, when executed by a computer, more particularly by the processor 7, cause the latter to implement the steps of the method 100 and the method 400. In particular, this recording medium 8 contains a computer program 9 comprising instructions which, when the program 9 is executed by a computer, in particular by the processor 7, cause the latter to implement the steps of the method 100 and the method 400.In the present example, the data processing device 3 is an “electronic control unit” (or “ECU”), the processor 7 is a microprocessor and the computer-readable recording medium 8 is a non-volatile memory adapted to store the computer program 9.

[0060] The fuel tank 4 comprises a fuel comprising a liquid phase and a gaseous phase, shown schematically on either side of the wave-shaped line. The fuel tank 4 comprises a temperature sensor 10 and a pressure sensor 11, located in the upper part of the fuel tank 4, that is to say in the area of ​​the fuel tank 4 in which fuel is found in the gaseous phase, under normal conditions of use of the vehicle. This pressure sensor 11 and this temperature sensor 10 are connected to the data processing device 3.

[0061] The canister 5 is connected to a heat engine 2 of the vehicle by means which will not be described.

[0062] The canister 5 is connected to the fuel tank 4 and to the atmosphere 12, illustrated by a shaft, by respective pipes illustrated schematically and by the double valve 6.

[0063] The double valve 6 makes it possible to open and close the connections between the canister 5 and the fuel tank 4 on the one hand and between the canister 5 and the atmosphere 12 on the other hand. This double valve 6 is preferably a solenoid valve, controlled by the data processing device 3. This double valve 6 could be replaced by two separate valves, in particular by a valve of the FTIV type (for "fuel tank isolation valve") making it possible to open and close the connection between the fuel tank 4 and the canister 5, and a valve of the CVS type (for "canister isolation valve") making it possible to open and close the connection between the canister 5 and the atmosphere 12.

[0064] On the, the double valve 6 is configured so as to leave open the connection between the canister 5 and the fuel tank 4 and to close the connection between the canister 5 and the atmosphere 12. Thus, the fuel tank 4 and the canister 5 form a system isolated from the outside.

[0065] In the, the double valve 6 is configured so as to close the connection between the canister 5 and the fuel tank 4, the connection between the canister 5 and the atmosphere also remaining closed. Thus, both the fuel tank 4 and the canister 5 are each isolated from the atmosphere and from each other.

[0066] I. Method for detecting the presence or absence of a fuel leak

[0067] With reference to the, a method 100 for determining the presence or absence of a fuel leak in the system 1 will now be described. It is implemented in the system 1 as illustrated in the, that is to say in which the fuel tank 4 is openly connected to the canister 5. This method 100 makes it possible to detect the presence or absence of a fuel leak in the subassembly formed by the fuel tank 4 and the canister 5 isolated from the outside. Thus, when we speak of the presence of a fuel leak or the absence of a fuel leak in the system 1, we will in practice designate the subassembly formed by the canister 5 and the fuel tank 4. The method could however be implemented in another subassembly or in the entire system.In this method 100, all the thresholds and predetermined values ​​are either calculated using mathematical functions which will not be described in detail, or are entered by a person skilled in the art into the data processing device 3 beforehand. When the thresholds and predetermined values ​​are calculated using mathematical functions, a variable of these mathematical functions is the atmospheric pressure.

[0068] It should be noted that certain steps described below allow one to conclude that there is a fuel leak if the tests presented are successful, but failure of these tests does not allow one to conclude that there is no fuel leak. Other steps, on the other hand, allow one to conclude that there is no fuel leak if the tests presented are successful, but failure of these tests does not allow one to conclude that there is a fuel leak. The succession of tests makes it very likely that there is no fuel leak or no fuel leak in system 1.

[0069] It should be noted that all the tests described below are passive, i.e. they do not require the generation of suction or vacuuming of the fuel system 1 or any other mechanical operation on containers 4 and 5.

[0070] In step 110, the heat engine 2 of the vehicle is started by a driver of the vehicle. The data processing device 3 determines a previous time period of stopping the heat engine 2 before this start. If this time period is greater than a predetermined time period, in particular two hours, step 120 is implemented. The duration of two hours is indeed sufficiently high for the pressure and temperature values ​​measured subsequently to be relevant. Alternatively, step 120 can also be implemented even if this duration is not respected, or if this duration is configured differently.

[0071] In step 120, the device 3 implements a measurement of a pressure value in the tank by the pressure sensor 11 and a measurement of temperature in the tank by the temperature sensor 10.

[0072] In step 130, the device 3 implements, in a first group of steps, a comparison between the pressure value, in absolute value, and a predetermined minimum pressure threshold.

[0073] In step 140, when the pressure value is higher, in absolute value, than the minimum pressure threshold, the device 3 concludes that there is a preliminary indication of the absence of fuel leakage in the system.

[0074] Steps 150 and 160 are implemented in the absence of a preliminary indication following step 140.

[0075] In step 150, the device 3 implements, in another group of steps, a comparison between the pressure value and another predetermined pressure threshold, and a comparison between the temperature and a boiling temperature threshold.

[0076] In step 160, when the pressure value is higher, in absolute value, than the other pressure threshold, and the temperature is lower than the boiling temperature threshold, the device 3 concludes that there is a preliminary indication of the absence of fuel leakage in the system.

[0077] Alternatively, steps 150 and 160 may be implemented first, and steps 130 and 140 are then implemented only in the absence of a preliminary indication following step 160.

[0078] In the event of a preliminary indication of the absence of a fuel leak, this result is stored by the device 3 in memory and will possibly be taken up in step 380, as described below. Thus, these steps alone do not allow a conclusion to be drawn. However, these preliminary indications are taken into account to conclude on the absence of a fuel leak if necessary when steps 170 to 370 described below do not allow a conclusion to be drawn. These measurements taken with the engine running therefore make it possible to obtain an answer on the presence or absence of a fuel leak, even in the event of indecision after the steps carried out with the engine off. Alternatively, they could be taken into account earlier in the method.

[0079] At step 170, the vehicle's thermal engine 2 is stopped by the driver.

[0080] In step 180, the device 3 implements steps of measuring, at different predetermined times of a period of time, respective pressure values ​​and temperature values ​​in the fuel tank 4, using the temperature sensor 10 and the pressure sensor 11. This period of time is here six hours. This means that, if the vehicle is restarted before the end of this period of time, the steps described from step 190 are not implemented, because the period of downtime is insufficient. Conversely, as long as the heat engine 2 is not restarted, it can be provided that the measurements continue to be carried out even after the end of this period of time. This duration of six hours corresponds to the minimum duration required in the CARB standard, to which the invention is adapted. This duration could, however, be configured to be different.The instants correspond, in the present example, to points in the time period located respectively, from the moment of stopping of the heat engine 2, and for a duration of six hours, at thirty minutes, 2h30, 3h30, 4h30, 6h00. They could be planned at different times, and be more or less numerous. However, it is advantageous that, for a duration of six hours, at least five instants are considered. Furthermore, it is advantageous not to consider too many instants to save the energy required by the method for determining the presence or absence of fuel leakage.

[0081] In step 190, the device 3 determines the number of instants, among the instants of step 180, having respective absolute pressure values ​​greater than a predetermined pressure threshold.

[0082] In step 200, when the number of instants determined in step 190 is greater than a predetermined threshold of number of instants, the device 3 concludes that there is no fuel leak in the subassembly formed by the canister 5 and the fuel tank 4, of the system 1, and the method 100 is stopped. None of the steps described subsequently are then implemented. The predetermined threshold of instants may for example be three, for five instants considered in total over the six-hour period. It may be different or depend on the number of measurements carried out in step 180, that is to say the number of instants considered over this period of time.

[0083] This analysis is particularly simple and quick because it only concerns pressure measurements. It allows a rapid conclusion to be drawn on the absence of fuel leaks if necessary and is based on the observation that, when over time, many pressures have remained high in system 1, it is very likely that there are no fuel leaks.

[0084] If no conclusion is reached at the end of step 200, step 210 is implemented.

[0085] In step 210, the device 3 determines, among the times of step 180, the two times whose respective pressure values ​​are the furthest from each other.

[0086] In step 220, when an absolute value of pressure difference between these two values ​​is less than or equal to a predetermined pressure difference threshold, the device 3 concludes that there is a fuel leak in the system. The method is stopped and none of the steps described subsequently are implemented.

[0087] This analysis also allows us to conclude without taking into account temperatures and in a very simple way. It is based on the observation that, if the pressure changes little over time, then it is likely that a fuel leak is present in system 1. The predetermined pressure difference threshold corresponds, in particular, to a threshold below which it was found that all the systems tested presented a fuel leak.

[0088] If no conclusion is reached at the end of step 220, step 230 is implemented.

[0089] In step 230, the device 3 determines the presence or absence, among the instants, of two instants for which a difference value between the respective temperature values ​​is greater than a predetermined temperature difference threshold, these two instants also having respective pressure values ​​lower than a predetermined pressure threshold and higher than the opposite of this pressure threshold. The temperature difference threshold is 3°C and the pressure threshold is a function of atmospheric pressure, which will not be described here.

[0090] In step 240, when the two instants of step 230 are determined to be present, the device 3 concludes that there is a fuel leak in the system 1, and the method 100 is stopped.

[0091] This analysis is therefore based on the observation that, if over time, in particular over a period of six hours including, for example, five moments which were the subject of measurements, we find two moments in which the temperature change is significant and for which the pressures are located in specific ranges (between the threshold and the opposite of this threshold), then a fuel leak is probable.

[0092] Steps 230 and 240 could alternatively be implemented before steps 210 and 220, which would only be implemented if there is no conclusion at the end of step 240. In another variant, steps 210 and 220 on the one hand, and 230 and 240 on the other hand, are implemented in parallel.

[0093] If no conclusion is reached at the end of these steps 200 to 240, step 250 is implemented.

[0094] In step 250, the device 3 determines whether at least one of the instants has a temperature above a predetermined boiling temperature threshold. If so, step 260 is implemented. Otherwise, the method is continued from step 320.

[0095] In step 260, when at least one instant, among the instants of step 180, has a temperature value greater than a predetermined boiling threshold, the device 3 determines, among the instants, the two instants describing a drop in temperature over time and for which the difference between the respective temperature values ​​is the highest.

[0096] In step 270, the device 3 compares this difference between the respective temperature values ​​with a predetermined temperature difference threshold. This threshold is 3°C. It could be different.

[0097] In step 280, the device 3 determines the difference between the respective pressure values ​​of these two instants.

[0098] In step 290, the device 3 compares this difference between the respective pressure values ​​with a predetermined pressure difference threshold. This threshold is a function of atmospheric pressure and will not be described here.

[0099] In step 300, the device 3 compares the pressure of the instant with the lowest temperature, among the two instants, with a predetermined pressure threshold. This threshold is also a function of atmospheric pressure and will not be described here.

[0100] In step 310, when the difference between the respective temperature values ​​is greater than the predetermined temperature difference threshold, the difference between the pressure values ​​is greater than the pressure value threshold or less than the opposite of this threshold, and the pressure at the instant with the lowest temperature is greater than the predetermined pressure threshold or less than the opposite of this threshold, the device 3 concludes that there is no fuel leak in the system. The following steps are then not implemented, the method 100 is stopped.

[0101] Thus, this analysis is more precise than the others. It is only carried out in the event of no conclusion of the presence or absence of a fuel leak at the end of the previous steps and concerns the case where at least one of the instants has a boiling temperature. The analysis is therefore specific to particularly high temperatures or which have been high at least at one moment during the period. Alternatively, it could be implemented earlier in the method 100.

[0102] In step 320, when no instant of step 180 has a temperature value greater than a predetermined boiling threshold, the device 3 determines, among the instants, two instants for which the difference between the respective temperature values ​​is the highest.

[0103] In step 330, the device 3 compares this highest difference between the respective temperature values ​​with a predetermined temperature difference threshold. This threshold is 3°C but could be different.

[0104] In step 340, the device 3 determines the difference between the respective pressure values ​​of these two instants.

[0105] In step 350, the device 3 compares this difference between the respective pressure values ​​with a predetermined pressure difference threshold. This threshold is a function of atmospheric pressure and will not be described.

[0106] In step 360, when the highest difference between the respective temperature values ​​is greater than the predetermined temperature difference threshold, and the difference between the respective pressure values ​​is greater than the pressure value threshold or less than the opposite of this threshold, the device 3 concludes that there is no fuel leak in the system. The method 100 is then stopped.

[0107] Thus, this analysis is also more precise than the others, it concerns the case where no measured temperature corresponds to boiling. It is only carried out in the event of no conclusion of the presence or absence of fuel leakage at the end of the previous steps. Alternatively, it could be implemented earlier in the process 100.

[0108] Alternatively to step 360, this analysis from steps 320 to 350 can make it possible to conclude that there is a fuel leak. Thus, in step 370, implemented instead of or in parallel with step 360, when the highest difference between the respective temperature values ​​is greater than the predetermined temperature difference threshold, but the difference between the respective pressure values ​​is less than the pressure value threshold or greater than the opposite of this threshold, the device 3 concludes that there is a fuel leak in the system. The method 100 is then stopped.

[0109] This step 370 is implemented with the threshold values ​​of steps 330 and 350, but it could alternatively be implemented with other threshold values.

[0110] Step 380 is implemented only if none of the preceding steps has led to a conclusion, i.e. the device 3 has concluded neither the presence of a leak nor the absence of a leak. In this case, at this step 380, the device 3 checks whether it has stored the result of steps 100 to 160. Thus, if at the end of steps 100 to 160, a preliminary indication of the absence of a fuel leak has been determined by the device, then the device 3 concludes at this step 380 that there is no fuel leak in the system 1.

[0111] If no preliminary indication has been made, the device 3 determines that it cannot conclude either the presence or the absence of a fuel leak in the system 1. The method can then be continued, that is to say that the measurements of step 180 are continued, or resumed if they had been stopped, until the heat engine 2 is restarted. The method can then be resumed, in particular steps 170 and following, after a subsequent shutdown of the heat engine of the vehicle, for a further period of at least six hours for example. The more measurements there are spread out over time, the more likely it is that the comparison steps implemented will make it possible to conclude the presence or absence of a fuel leak.

[0112] Prior to the steps described, in the case where the double valve 6 is configured differently from the mode of the, this method 100 for detecting a fuel leak provides steps, implemented by the device 3, which controls the opening of the connection between the fuel tank 4 and the canister 5, and the isolation of the fuel tank 4 and the canister 5 from the heat engine 2 and the atmosphere, to find the configuration of the, unless this method concerns the second test of the method 400 described below.

[0113] This method 100 is not limited to the embodiments presented and other embodiments will become apparent to those skilled in the art.

[0114] This method is thus suitable for any fuel system as defined at the beginning of the text. It can in particular be implemented for containers other than the fuel tank 4 and the canister 5. It can in particular be implemented in the fuel tank 4 alone, isolated from the canister 5, or in the canister 5 alone, or in any container in which a pressure sensor and a temperature sensor can be placed and connected to the data processing device 3.

[0115] II. Method for locating a fuel leak

[0116] A method 400 for locating a fuel leak in a fuel system will now be described, with reference to the.

[0117] In step 410, the system 1 comprising a fuel tank 4 and a canister 5 connected in an open manner to each other, as illustrated in the, the device 3 carries out a first test to determine the presence or absence of a fuel leak in said system 1 comprising the fuel tank 4 and the canister 5. This first test corresponds to the method 100 described above. It therefore makes it possible to detect the presence or absence of a fuel leak in the subassembly formed by the fuel tank 4 and the canister 5.

[0118] In step 420, when the presence of a fuel leak is determined at the end of the first test, that is to say at the end of the method 100, the device 3 implements the closing of the connection, by the double valve 6, between the fuel tank 4 and the canister 5 so as to isolate the two containers from each other. The system 1 is then in the configuration illustrated in the. The rest of the method 400 takes place on the system configured in this state.

[0119] In step 430-A, the device 3 immediately begins a second test to determine the presence or absence of a fuel leak in the first container. This is the same method 100, implemented for the second time, with the exception of steps 110 to 160, since the heat engine 2 is stopped. Thus, steps 170 and following, until the method 100 is stopped in accordance with what was described previously, are implemented again. However, this time, the fuel tank 4, in which the temperature and pressure measurements are implemented, is isolated from the canister 5. The detection of a fuel leak therefore only concerns the fuel tank 4. This second test, implemented immediately after the first test, includes a period of time corresponding to step 180 which lasts until the heat engine 2 is restarted.In this step, the times corresponding to the pressure and temperature measurements in the fuel tank 4 are separated by thirty minutes. This interval could be different. The number of times therefore depends on this duration and these intervals. Generally speaking, the longer the period of time, that is to say the longer the vehicle remains stopped, the more likely this second test is to result in the detection of a fuel leak or absence of a fuel leak in the fuel tank 4.

[0120] In an alternative step 430-B, the time period of this second test is predetermined to last two hours. This is a duration which is generally sufficient to allow a sufficient number of measurements and therefore for the device 3 to conclude on the presence or absence of a fuel leak in the fuel tank 4. To a time period of the first test of six hours is therefore added a time period for this second test of two hours.

[0121] In an alternative step 430-C, it is planned to configure the time period of the first test, carried out when the connection between the fuel tank 4 and the canister 5 is open, so that it lasts four hours instead of six hours when it is associated with the second test. By adding the time period of this second test of two hours, the set formed by the first and second tests lasts six hours, which makes it possible to provide a method for detecting fuel leaks, but also for locating the leak if necessary, lasting six hours, which meets the “CARB” (for “California Air Resources Board”) standard while optimizing the time taken by each of the two tests.

[0122] In an alternative step 430-D, this second test does not begin immediately after the first. Thus, when the first test results in the detection of a fuel leak, this result is stored in memory by the device 3. The thermal engine of the vehicle is subsequently restarted by the driver, and it is only at the following cycle, i.e. at the next shutdown of the thermal engine 2, that the second test begins, with the connection closed between the fuel tank 4 and the canister 5. In other words, since the shutdown of the thermal engine 2 is a first shutdown, the second test is implemented after a second shutdown of the thermal engine 2 itself following a restart of the thermal engine 2 following the first test. In this alternative, the time period of the measurements of step 180 is predetermined to last six hours for this second test.This second test is therefore carried out under the same conditions as the first test, which increases the chances of reaching a conclusion on the presence or absence of a fuel leak in the fuel tank 4. It is recalled that, for any second test, it is planned to close the connection between the fuel tank 4 and the canister 5, a connection which may have been reopened in the meantime following the restart of the thermal engine 2.

[0123] In step 440, when the presence of a fuel leak is detected at the end of the second test, the device 3 concludes that a fuel leak has been located in the fuel tank 4, or when the absence of a fuel leak is detected at the end of the second test, the device 3 concludes that a fuel leak has been located in the canister 5. Indeed, since it is already known, thanks to the result of the first test, that the subassembly formed by the fuel tank 4 and the canister 5 has a leak, closing the connection between the fuel tank 4 and the canister 5 and repeating the method 100 for this second test makes it possible to determine whether the fuel leak concerns the fuel tank 4 or the canister 5.

[0124] The following steps are implemented if the device fails to reach a conclusion after the second test.

[0125] In step 450, in the absence of a conclusion on the location of the fuel leak at the end of the second test, after a shutdown of the heat engine 2 itself following a restart of the heat engine following the second test, the device 3 implements a step of closing the connection between the fuel tank 4 and the canister 5 of the system 1 so as to isolate these two containers from each other again. Indeed, the heat engine having restarted, it is possible that this connection is open. This step therefore amounts to finding oneself in the state of the.

[0126] In step 460, the device performs a third test for determining the absence or presence of a fuel leak in the fuel tank 4 of the system, continued for a predetermined period of time of at least six hours. This third test is the same as the second test, i.e., method 100, except for steps 110 to 160.

[0127] Thus, this third test takes place when the second test has been interrupted by restarting the vehicle before the predetermined time period is reached, or when the device 3 has not been able to conclude on the location of the fuel leak. It makes it possible to extend the search for the location of the leak, by repeating these steps 170 and following in the tank isolated from the outside, on the following cycle, that is to say when the heat engine 2 is stopped again.

[0128] Fourth, fifth and other tests may follow one another at each stop of the thermal engine 2, always in the isolated fuel tank 4, as long as the fuel leak has not been located. Alternatively, it may be provided to stop these tests. It may in particular be provided to resume the first test, that is to say the detection of the presence or absence of fuel leak in the subsystem formed by the fuel tank 4 and the canister 5, when the device 3 has not been able to conclude that the fuel leak has been located after a certain number of tests in the isolated fuel tank 4.

[0129] We remind you that all these tests are passive in that they do not require the generation of suction or vacuuming of the fuel system 1 or any other mechanical operation on containers 4 and 5.

[0130] This description also discloses a fuel system 1 for a vehicle equipped with a heat engine 2 comprising:

[0131] - a first and a second container, the fuel tank 4 and the canister 5, connected to each other;

[0132] - a valve 6 for opening and closing the connection between the first and second container;

[0133] - a device 3 for implementing the steps of methods 100 and 400.

[0134] The invention is not limited to the embodiments presented and other embodiments will become apparent to those skilled in the art.

[0135] In particular, the invention is not limited to the fuel tank 4 and the canister 5, it can be implemented for any type of container connected to each other by a connection which can be opened and closed.

[0136] Furthermore, instead of the detection method 100, any method for detecting the presence of a fuel leak in a container is covered by the method 400. Indeed, the invention aims to use a fuel leak detection method at least twice to locate the leak, in this it is not limited to a particular fuel leak detection method. It is also possible that the first and second tests do not include the same fuel leak detection steps.

[0137] Finally, it is recalled that, instead of the double valve 6, a standard single valve, of the “FTIV” type, is sufficient to isolate the connection between the tank 4 and the canister 5. List of references

[0138] 1: fuel system2: thermal engine of a vehicle3: data processing device

[0139] 4: fuel tank

[0140] 5: canister

[0141] 6: double valve

[0142] 7: processor

[0143] 8: computer-readable recording medium

[0144] 9: computer program

[0145] 10: temperature sensor

[0146] 11: pressure sensor

[0147] 12: atmosphere

[0148] 100: method for determining the presence or absence of a fuel leak

[0149] 400: method for locating a fuel leak

Claims

Method (400) for locating a fuel leak in a pressurized fuel system (1) for a vehicle equipped with a heat engine (2), comprising the following steps: - the system (1) comprising a first container (4) and a second container (5) openly connected to each other, first passive test (410) for determining the presence or absence of a fuel leak in said system (1) comprising the first (4) and second containers (5); - when the presence of a fuel leak is determined at the end of the first test (100): * closing (420) the connection between the first (4) and the second (5) container so as to isolate the two containers from each other; * second passive test (430) for determining the presence or absence of a fuel leak in the first container (4);* when the presence of a fuel leak is detected at the end of the second passive test (430), conclusion (440) of the location of a fuel leak in the first container (4), or when the absence of a fuel leak is detected at the end of the second test, conclusion of the location of a fuel leak in the second container (5), the first and second passive tests being passive in that they do not require generation of suction or vacuuming of the fuel system (1) nor any other mechanical operation on the first (4) and second (5) containers.; Method (400) according to the preceding claim, in which the first passive test (410) comprises the following steps: - after a stoppage (170) of the thermal engine (2) of the vehicle, measurements (180), at different predetermined times during a period of time, of respective pressure values ​​in the system (1); - determination (210), among the times, of the two times whose respective pressure values ​​are the furthest from each other; - when an absolute value of pressure difference between these two values ​​is less than or equal to a predetermined pressure difference threshold, conclusion (220) of the presence of a fuel leak in the system (1) and stopping the method (100). Method (400) according to claim 1, wherein the first (410) and second (430) passive tests for determining the presence or absence of a fuel leak comprise steps of:- measuring (180), at different predetermined instants of respective first and second time periods, pressure and temperature values ​​in the first container of the system (1);- comparing (130, 150, 270, 290, 300, 330, 350) at least one of the values ​​to a predetermined threshold. Method (400) according to any one of the preceding claims, wherein the first passive test (410) is implemented following a shutdown of a thermal engine (2) of the vehicle and for a predetermined period of time, preferably at least four hours, in particular at least six hours. Method (400) according to the preceding claim, in which the second passive test is implemented immediately (430-A, 430-B, 430-C) after the end of the first passive test (410) when the presence of a fuel leak has been detected at the end of this first passive test (410). The method (400) of claim 5, wherein the second passive test is continued for a predetermined period of time (430-B, 430-C), preferably at least two hours. Method (400) according to claim 5, wherein the second passive test (430-A) is continued until a restart of the vehicle equipped with a thermal engine. Method (400) according to any one of claims 1 to 4, in which, the stopping of the heat engine (2) being a first stop, the second passive test (430-D) is implemented after a second stopping of the heat engine (2) itself following a restart of the heat engine (2) following the first passive test, the second passive test being continued for a predetermined period of time, preferably at least six hours. Method (400) according to any one of claims 5 to 8, comprising, in the absence of a conclusion on the location of the fuel leak at the end of the second passive test, after a shutdown of the heat engine (2) itself following a restart of the heat engine (2) following the second passive test, the following steps: - closing (450) the connection between the first (4) and the second (5) container of the system so as to isolate the two containers from each other; - third passive test (460) for determining the absence or presence of a fuel leak in the first container (4) of the system (1), continued for a predetermined period of time, preferably at least six hours, the third test being passive in that it does not require generation of suction or vacuuming of the fuel system (1) nor any other mechanical operation on the first (4) and second (5) containers. A method (400) according to any preceding claim, wherein the first container (4) of the system is a fuel tank and the second container (5) is a canister, the opening and closing of the connection being operated by a valve (6). Data processing device (3) comprising a processor (7) adapted to the steps of the method (400) according to any one of the preceding claims, for implementing said steps of the method. Fuel system (1) for a vehicle equipped with a heat engine (2) comprising:- a first (4) and a second container (5) connected to each other;- a valve (6) for opening and closing the connection between the first (4) and the second container (5);- a device (3) according to claim 11 for implementing the steps of the method according to any one of claims 1 to 10 in the system (1). Vehicle equipped with a thermal engine (2) comprising a fuel system (1) according to the preceding claim. Computer program (9) comprising instructions which, when the program is executed by a computer, cause the latter to implement the steps of the method (400) according to any one of claims 1 to 10. A computer-readable recording medium (8) comprising instructions which, when executed by a computer, cause the computer to carry out the steps of the method (400) according to any one of claims 1 to 10.

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