Identifying the location of a fuel leak within the fuel system.

Abstract

The present invention relates to a method for locating a fuel leak in a pressurized fuel system (1) of a vehicle equipped with a heat engine (2), comprising the following steps: - A system (1) includes a first container (4) and a second container (5) that are openly connected to each other, and a first test is performed to determine whether or not there is a fuel leak in the system (1) including the first container (4) and the second container (5), - If a fuel leak is detected as a result of the first test (100), * The steps include closing the connection between the first container (4) and the second container (5) that separate the two containers from each other, * A second test is performed to determine whether or not there is a fuel leak in the first container (4), * If the second test detects a fuel leak, the step is to conclude that the location of the fuel leak is inside the first container (4), or if the second test detects no fuel leak, the step is to conclude that the location of the fuel leak is inside the second container (5). Regarding methods including

Description

Technical Field

[0001] The present invention relates, in particular, to identifying the location of fuel leakage in a vehicle fuel system after the heat engine of the vehicle has stopped. More specifically, the present invention relates to a passive location identification method, that is, a method that does not require the generation of suction or evacuation of the fuel system, nor any other mechanical operation on the container.

Background Art

[0002] In the prior art, especially according to Patent Document 1, a passive determination method for the presence or absence of fuel leakage in a pressurized fuel system of a vehicle equipped with a heat engine is already known. This method is carried out after the heat engine has stopped. This method includes a step of measuring pressure and temperature at several points within a certain period of time, and a step of calculating the first maximum temperature difference between each of these points following this step. If this first temperature difference exceeds a predetermined temperature difference threshold value, this method includes a step of calculating the pressure difference between the corresponding two points in time. If this pressure difference is below a predetermined pressure difference threshold value, this method concludes that there is fuel leakage in the fuel system.

[0003] The drawback of this method is that when it concludes that there is fuel leakage, it cannot identify the location of the fuel leakage within the system. Therefore, in order to repair the fuel leakage, it is necessary to disassemble and even replace the entire system, which is complex and costly.

[0004] Patent Document 2, Patent Document 3 and Patent Document 4 each teach a method for detecting leakage within a fuel system.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

[0006] The primary objective of this invention is to enable the passive identification of fuel leak locations within a fuel system, regardless of whether the fuel is in liquid or gaseous state. [Means for solving the problem]

[0007] For this purpose, the present invention provides a method for locating a fuel leak in a pressurized fuel system of a vehicle equipped with a heat engine, comprising the following steps: - A system comprising a first container and a second container openly connected to each other, and a first passive test being performed to determine whether or not there is a fuel leak in the system including the first container and the second container, - If a fuel leak is detected as a result of the first passive test, * The steps include closing the connection between the first container and the second container, which separates the two containers from each other, * A second passive test is performed to determine whether or not there is a fuel leak in the first container, * A step in which, if a fuel leak is detected as a result of the second passive test, the conclusion is drawn that the location of the fuel leak is inside the first container, or, if no fuel leak is detected as a result of the second passive test, the conclusion is drawn that the location of the fuel leak is inside the second container. The objective is a method that includes, and in which the first passive test and the second passive test are passive in that they do not require the generation of suction or vacuum of the fuel system, nor any other mechanical operation on the first and second vessels. [Effects of the Invention]

[0008] Thus, by performing a second passive test after isolating the first and second containers from each other, the location of the fuel leak detected in the first passive test can be determined to be either within the first or second container. In other words, this method allows for the determination of whether the fuel leak is located within the first or second container simply by closing the connection and performing a second passive fuel leak detection test. Therefore, this method is extremely easy to implement. All that is required is a single test to determine the presence or absence of a fuel leak in the fuel system, performed within one container, and a means of closing the connection between one container and the other in the system. These two elements, namely the passive detection test and the connection closing means, may already be present in the vehicle, thus allowing for the easy and low-cost implementation of this location method. In this way, when repairing a fuel leak, only the faulty container is dismantled and / or replaced, rather than both containers together.

[0009] A "fuel system" refers to a device incorporated into a vehicle equipped with a heat engine, whose function is the storage, purification, measurement, or transport of fuel supplied to the heat engine. A fuel system includes at least one fuel tank and fuel supply lines to the heat engine. A fuel system may also include one or more accessories, namely fuel tank vent valves and vent lines, filling tubes, canisters, fuel filters, fuel pumps, fuel tank gauges, electrical connectors, lids, and any other components through which fuel, typically in liquid and / or gaseous form, passes, such as fuel evaporative gas circulation lines.

[0010] Vehicles equipped with a heat engine can, in particular, be hybrid vehicles.

[0011] The following are any other features that may be adopted individually or in combination:

[0012] Preferably, the first passive test is: - A step of measuring the pressure values ​​in the system at predetermined different points in time within a certain period after the vehicle's heat engine has been shut down, - A step of determining two time points at which the pressure values are furthest apart from each other among all time points; - When the absolute value of the difference between these two pressure values is less than or equal to a predetermined pressure difference threshold value, steps of deriving the conclusion that there is a fuel leak in the system, and stopping this method; are included.

[0013] Thus, in order to conclude that there is a fuel leak, it is only necessary to measure the pressure within a certain period of time and determine the maximum pressure difference, that is, the difference between the minimum pressure and the maximum pressure measured within this certain period of time. In fact, this method is based on the fact that when it is below a predetermined pressure difference threshold value, that is, when the pressure change within the corresponding certain period of time is extremely small, it can be concluded with high accuracy that there is a fuel leak in the fuel system without considering the temperature. That is, this method can be implemented very simply.

[0014] Note that even if it is not concluded that there is a fuel leak as a result of these steps, this does not necessarily mean that it is concluded that there is no fuel leak. In this case, other steps can be implemented to draw one of these conclusions.

[0015] The "time point" is understood as a point within a certain period of time corresponding to a certain pressure in the fuel system.

[0016] Advantageously, the first passive test and the second passive test for determining the presence or absence of a fuel leak are - steps of measuring the pressure value and the temperature value in the first container of the system at predetermined different time points within the first period of time and within the second period of time; - steps of comparing at least one numerical value with a predetermined threshold value; are included.

[0017] Thus, the test performed twice to determine the presence or absence of a fuel leak includes any simple steps such as temperature measurement and pressure measurement in one or more containers, and comparison with a threshold value.

[0018] Preferably, the first passive test is carried out for a predetermined time, preferably at least 4 hours, especially at least 6 hours, following the shutdown of the vehicle's heat engine.

[0019] Thus, the present invention is particularly suitable for the US standard called "CARB" ("California Air Resources Board") which requires an observation time of 6 hours.

[0020] Advantageously, if fuel leakage is detected as a result of the first passive test, the second passive test is carried out immediately after the end of this first passive test.

[0021] Thus, if fuel leakage is detected as a result of the first test, the connection between the two containers is immediately closed and the second test is started to locate the position of this fuel leakage.

[0022] Preferably, the second passive test is continued for a predetermined time, preferably at least 2 hours.

[0023] Thus, the second test is economical because it is stopped in a predetermined manner.

[0024] Alternatively, the second passive test is continued until the vehicle with the heat engine is restarted.

[0025] In this case, the second test is less economical, but since it is continued until the vehicle is restarted, the number of measurements to be carried out may increase due to the extended time. That is, the longer the time and the more the number of measurements, the easier it is to detect fuel leakage, so the possibility of locating the fuel leakage increases.

[0026] Alternatively, if the shutdown of the heat engine is taken as the first shutdown, the second passive test is carried out after the second shutdown of the heat engine which occurs after the restart of the heat engine following the first passive test, and the second passive test is continued for a predetermined time, preferably at least 6 hours.

[0027] Thus, the second test is only started in the "next cycle," that is, after the heat engine has stopped again. In other words, this alternative is more economical than the previous two alternatives, but because it requires waiting for this new cycle, the time required to locate the fuel leak is relatively longer. However, in this alternative, the second test is more accurate than the previous two alternatives and shows the same accuracy as the first test. This is because it is started simultaneously with the shutdown of the heat engine and is conducted under the same conditions as the first test, such as being able to continue for a sufficiently long period of time, for example, six hours.

[0028] Advantageously, if the location of the fuel leak cannot be identified as a result of the second passive test, this method is performed after the heat engine has been shut down following the restart of the heat engine that follows the second passive test, and then the following steps are taken. - A step of closing the connection between the first container and the second container of a system that isolates two containers from each other, - A step of performing a third passive test to determine whether or not there is a fuel leak in the first vessel of the system, which is continued for a predetermined time, preferably for at least 6 hours, wherein the third passive test is passive in that it does not require the generation of suction or vacuum of the fuel system, nor any other mechanical operation on the first and second vessels. Includes.

[0029] Thus, if the location of the fuel leak is not identified as a result of the second test and the vehicle resumes operation, the second test is repeated in the next cycle, becoming the "third test." Therefore, although it takes time, the location of the fuel leak can be identified without having to restart the fuel leak detection process using the first test from the beginning.

[0030] Preferably, the first container of the system is a fuel tank, the second container is a canister, and the connection is opened and closed by a valve.

[0031] Thus, the first test allows for the detection of fuel leaks within this subassembly formed from the tank and canister, and the second test allows for the determination of whether the fuel leak is located in the tank or the canister.

[0032] According to the present invention, a data processing device including a processor adapted to the steps of the method is also conceivable for carrying out each step of the method described above.

[0033] This device is, in particular, a vehicle-mounted control unit.

[0034] According to the present invention, - A first container and a second container connected to each other, - A valve for opening and closing the connection between the first container and the second container, - Apparatus as described above for carrying out the steps of the above method A vehicle fuel system equipped with a heat engine is also conceivable.

[0035] The valve can be a standard isolation valve of type "FTIV" (fuel tank isolation valve) if the two vessels are a tank and a canister, or it can be a double valve with another stage that opens and closes the connection between the second vessel and the atmosphere.

[0036] According to the present invention, a vehicle equipped with a heat engine including the fuel system described above is also conceivable.

[0037] According to the present invention, a computer program is also conceivable that includes instructions to cause a computer to perform the steps of the method described above when the program is executed by the computer.

[0038] According to the present invention, a computer-readable recording medium is also envisioned, which includes instructions that cause a computer to perform the steps of the above-described method when the instructions are executed by a computer.

[0039] The present invention will be better understood by referring to the attached drawings and reading the following description, which is merely an example. [Brief explanation of the drawing]

[0040] [Figure 1] This is a schematic diagram of the fuel system according to the present invention. [Figure 2] This is a schematic diagram of the system in Figure 1 in a different configuration. [Figure 3] This is a flowchart of a fuel leak detection method. [Figure 4] This is a flowchart of the fuel leak location identification method according to the present invention. [Modes for carrying out the invention]

[0041] One embodiment of the fuel system 1 of the present invention is shown in Figures 1 and 2. This fuel system 1 is a pressurized fuel system for a vehicle's heat engine 2. This system is mounted on a vehicle (not shown). The vehicle may be a hybrid vehicle or otherwise. This system includes a data processing unit 3, a fuel tank 4, a canister 5, and a dual valve 6.

[0042] The data processing device 3 includes a processor 7 adapted to the steps of methods 100 and 400, described later, in order to carry out the steps of those methods. The word "adapted" means that the processor 7 is configured specifically for carrying out these methods. The data processing device 3 further includes a computer-readable recording medium 8 which contains instructions that cause a computer to carry out the steps of methods 100 and 400 when the instructions are executed by the computer, more specifically by the processor 7. In particular, the recording medium 8 contains a computer program 9 which contains instructions that cause a computer to carry out the steps of methods 100 and 400 when the program 9 is executed by the computer, in particular by the processor 7. In this example, the data processing device 3 is an "electronic control unit" (ECU), the processor 7 is a microprocessor, and the computer-readable recording medium 8 is a non-volatile memory adapted for storing the computer program 9.

[0043] The fuel tank 4 contains fuel consisting of a liquid phase and a gas phase, as illustrated by double dashed lines. The fuel tank 4 includes a temperature sensor 10 and a pressure sensor 11 located in the upper part of the fuel tank 4, i.e., within the zone of the fuel tank 4 where the gas phase fuel is present under the normal operating conditions of the vehicle. The pressure sensor 11 and temperature sensor 10 are connected to the data processing device 3.

[0044] The canister 5 is connected to the vehicle's heat engine 2 by means not shown.

[0045] The canister 5 is connected to the fuel tank 4 and the atmosphere 12, shown by the tree illustration, respectively, by the tubes and double valve 6 shown schematically.

[0046] The dual valve 6 can open and close the connection 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 dual valve 6 is preferably a solenoid valve controlled by the data processing device 3. This dual valve 6 may be replaced with two separate valves, in particular an FTIV ("fuel tank isolation valve") type valve capable of opening and closing the connection between the fuel tank 4 and the canister 5, and a CVS ("canister isolation valve") type valve capable of opening and closing the connection between the canister 5 and the atmosphere 12.

[0047] In Figure 1, the double valve 6 is configured to 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. In this way, the fuel tank 4 and the canister 5 form a system isolated from the outside.

[0048] In Figure 2, the double valve 6 is configured to close the connection between the canister 5 and the fuel tank 4, and the connection between the canister 5 and the atmosphere also remains closed. In this way, the fuel tank 4 and the canister 5 are isolated from the atmosphere and form a system that is isolated from each other.

[0049] I. Method for detecting fuel leaks From here, the method 100 for determining the presence or absence of fuel leaks in System 1 will be described with reference to Figure 3. This method is performed within System 1 as shown in Figure 1, that is, within System 1 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 fuel leaks in the subassembly formed from the fuel tank 4 and the canister 5, which are isolated from the outside. Thus, when referring to the presence or absence of fuel leaks in System 1, the subassembly formed from the canister 5 and the fuel tank 4 is usually assumed. However, this method is thought to be applicable to other subassemblies or the entire system. In this method 100, predetermined thresholds and numerical values ​​are both calculated using mathematical functions (not described in detail) or input in advance into the data processing device 3 by a person skilled in the art. When predetermined thresholds and numerical values ​​are calculated using mathematical functions, the variables of these mathematical functions are atmospheric pressure.

[0050] It should be noted that some of the steps described later allow us to conclude that a fuel leak exists if the presented tests are successful, but we cannot conclude that there is no fuel leak even if these tests fail. Conversely, in the other steps, we can conclude that there is no fuel leak if the presented tests are successful, but we cannot conclude that there is a fuel leak even if these tests fail. By performing this series of tests, it becomes possible to conclude with a very high degree of probability whether or not there is a fuel leak in System 1.

[0051] It should be noted that all tests described later are passive, meaning they do not require suction generation or vacuuming of fuel system 1, nor any other mechanical operation on containers 4 and 5.

[0052] In step 110, the vehicle's heat engine 2 is started by the vehicle's driver. The data processing device 3 determines the previous shutdown time of the heat engine 2 prior to this start. If this time is longer than a predetermined time, particularly two hours, step 120 is performed. In fact, two hours is sufficient to obtain appropriate pressure and temperature values ​​in subsequent measurements. In modified embodiments, step 120 may be performed even if this time is not observed or if a different time is set.

[0053] In step 120, the device 3 measures the pressure value inside the tank using the pressure sensor 11 and measures the temperature inside the tank using the temperature sensor 10.

[0054] In step 130, the device 3 compares the absolute value of the pressure with a predetermined minimum pressure threshold within the first group of steps.

[0055] In step 140, if the pressure value is above the minimum pressure threshold in absolute terms, device 3 tentatively suggests that there is no fuel leak in the system.

[0056] If no preliminary indications are given as a result of step 140, steps 150 and 160 are performed.

[0057] In step 150, the apparatus 3 performs a comparison between the pressure value and another predetermined pressure threshold, and a comparison between the temperature and the boiling point threshold, within a separate group of steps.

[0058] In step 160, if the pressure value is above this other pressure threshold in absolute value and the temperature is below this boiling point threshold, device 3 tentatively suggests that there is no fuel leak in the system.

[0059] Alternatively, first perform steps 150 and 160, and only if the results of step 160 do not provide any preliminary indications, then perform steps 130 and 140.

[0060] If the results suggest that there is no fuel leak, this result is stored in memory by device 3 and retrieved again in step 380 as needed, as described later. Thus, it is not possible to draw conclusions from these steps alone. However, these preliminary suggestions are considered as needed to conclude that there is no fuel leak if no conclusion is reached in steps 170 to 370, as described later. In other words, these measurements performed with the engine ignited can provide an answer regarding the presence or absence of a fuel leak, even if no conclusion is reached after performing the steps with the engine stopped. Alternatively, these measurements could be considered relatively early in this method.

[0061] In step 170, the vehicle's heat engine 2 is stopped by the driver.

[0062] In step 180, the device 3 uses the temperature sensor 10 and the pressure sensor 11 to measure the pressure and temperature values ​​in the fuel tank 4 at predetermined different points in time within a certain period. Here, this period is 6 hours. This means that if the vehicle is restarted before this period has elapsed, the steps from step 190 onward will not be performed due to insufficient stopping time. Conversely, unless the heat engine 2 is restarted, it can be assumed that measurements will continue to be performed even after this period has elapsed. This 6-hour duration corresponds to the shortest time required by the CARB standard to which the present invention conforms. However, it is also possible to set a different duration. In this example, when the duration is 6 hours, each point in time corresponds to 30 minutes, 2 hours 30 minutes, 3 hours 30 minutes, 4 hours 30 minutes, and 6 hours after the heat engine 2 has stopped, respectively. It is also possible to assume more or fewer points in time than this. However, when the duration is 6 hours, it is advantageous to set at least 5 points in time. Also, it is advantageous not to set too many points in time in order to save energy required for determining whether or not there is a fuel leak.

[0063] In step 190, the device 3 determines the number of time points in step 180 that show a pressure absolute value exceeding a predetermined pressure threshold.

[0064] In step 200, if the number of time points determined in step 190 exceeds a predetermined time point threshold, the device 3 concludes that there is no fuel leak in the subassembly of system 1 formed from the canister 5 and fuel tank 4, and method 100 is stopped. In this case, none of the subsequent steps are performed. The predetermined time point threshold can be, for example, 3 time points if a total of 5 time points are set for a 6-hour duration. It can be any other number, or it can be changed depending on the number of measurements performed in step 180, i.e., the number of time points set during this time.

[0065] This analysis is extremely simple and quick because it focuses solely on pressure measurements. Performing this analysis allows for a rapid conclusion that, in some cases, there is no fuel leak. This analysis is based on the fact that if a significant amount of pressure remains high in system 1 within this timeframe, there is a very high probability that there is no fuel leak in system 1 at all.

[0066] If no conclusion is reached as a result of Step 200, Step 210 will be carried out.

[0067] In step 210, the device 3 determines the two time points in step 180 whose pressure values ​​are furthest apart from each other.

[0068] In step 220, if the absolute value of the difference between these two pressure values ​​is less than or equal to a predetermined pressure difference threshold, device 3 concludes that there is a fuel leak in the system. This process is stopped, and none of the subsequent steps are performed.

[0069] This analysis also allows for very simple conclusions to be drawn without temperature. This analysis is based on the fact that if the pressure changes very little over time, there is a possibility of fuel leakage within system 1. The given pressure difference threshold corresponds to the threshold below which fuel leakage is observed in all systems under test, in particular.

[0070] If no conclusion is reached as a result of step 220, step 230 will be performed.

[0071] In step 230, the device 3 determines whether there are two points in time where the temperature difference exceeds a predetermined temperature difference threshold, and the pressure value falls below a predetermined pressure threshold and exceeds the inverse value of this pressure threshold. The temperature difference threshold is 3°C, and the pressure threshold is determined according to atmospheric pressure (not explained here).

[0072] If, in step 240, it is determined that there are two points in time from step 230, the device 3 concludes that there is a fuel leak in system 1, and method 100 is stopped.

[0073] In other words, this analysis is based on the fact that a fuel leak is possible if, within a 6-hour period including, for example, 5 time points being measured, there are two time points where the temperature changes significantly and the pressure is within a specific range (between a threshold and its opposite).

[0074] Steps 230 and 240 can be performed alternatively before steps 210 and 220, and steps 210 and 220 may be performed only if no conclusion is reached as a result of step 240. In other modified embodiments, steps 210 and 220 are performed in parallel, while steps 230 and 240 are performed in parallel.

[0075] If no conclusion is reached as a result of steps 200 through 240, step 250 is performed.

[0076] In step 250, the apparatus 3 determines whether the temperature exceeds a predetermined boiling point threshold at least once. If so, step 260 is performed. Otherwise, the process continues from step 320.

[0077] In step 260, if at least one of the time points in step 180 shows a temperature value exceeding a predetermined boiling point threshold, the apparatus 3 determines the two time points within that time that show the largest temperature decrease and temperature difference.

[0078] In step 270, the apparatus 3 compares this temperature difference with a predetermined temperature difference threshold. This threshold is 3°C. Other values ​​may also be used.

[0079] In step 280, the device 3 determines the difference between the pressure values ​​at these two points in time.

[0080] In step 290, the apparatus 3 compares this pressure difference with a predetermined pressure difference threshold. This threshold changes depending on the atmospheric pressure (this will not be explained here).

[0081] In step 300, the device 3 compares the pressure at the time point with the lower temperature among two time points with a predetermined pressure threshold. This threshold also changes according to atmospheric pressure (not described here).

[0082] In step 310, if the temperature difference exceeds a predetermined temperature difference threshold, the pressure difference exceeds a pressure threshold or falls below the inverse of this threshold, and the pressure at the lowest temperature exceeds a predetermined pressure threshold or falls below the inverse of this threshold, the device 3 concludes that there is no fuel leak in the system. In this case, the subsequent steps are not performed, and method 100 is terminated.

[0083] Thus, this analysis is more accurate than other analyses. This analysis is performed only if the results of the preceding steps have not led to a conclusion regarding the presence or absence of a fuel leak, and applies only when the boiling point is reached at least at one point in time. In other words, this analysis is suitable when the temperature is extremely high or when the temperature rises at least at one point in time. Alternatively, this analysis could be performed relatively early in Method 100.

[0084] In step 320, if no temperature value exceeding a predetermined boiling point threshold is observed at any point in step 180, the apparatus 3 determines the two points in time from which the temperature difference is largest.

[0085] In step 330, the apparatus 3 compares this maximum temperature difference with a predetermined temperature difference threshold. This threshold is 3°C, but other values ​​may also be used.

[0086] In step 340, the device 3 determines the difference between the pressure values ​​at these two points in time.

[0087] In step 350, the apparatus 3 compares this pressure difference with a predetermined pressure difference threshold. This threshold changes according to atmospheric pressure (not described here).

[0088] In step 360, if the maximum temperature difference exceeds a predetermined temperature difference threshold and the pressure difference exceeds or falls below a pressure threshold, the device 3 concludes that there is no fuel leak in the system. In this case, method 100 is stopped.

[0089] Thus, this analysis is more precise than the others and applies to cases where none of the measured temperatures correspond to the boiling point. This analysis is performed only if the results of the preceding steps have not led to a conclusion regarding the presence or absence of a fuel leak. Alternatively, this analysis could be performed relatively early in Method 100.

[0090] Alternatively, the analysis performed in steps 320 through 350 may conclude that there is a fuel leak. In step 370, which is performed in place of or in parallel with step 360, if the maximum temperature difference exceeds a predetermined temperature difference threshold, but the pressure difference falls below a pressure threshold or exceeds the inverse of this threshold, the device 3 concludes that there is a fuel leak in the system. In this case, method 100 is stopped.

[0091] Step 370 is performed using the thresholds from steps 330 and 350, but it may also be performed using other thresholds.

[0092] Step 380 is performed only if no conclusion has been reached in any of the preceding steps, that is, if the device 3 has not reached any conclusion regarding the presence or absence of a fuel leak. In this case, in step 380, the device 3 checks whether the results from steps 100 to 160 have been saved. If the device determines that the results from steps 100 to 160 indicate a provisional indication that there is no fuel leak, the device 3 concludes in step 380 that there is no fuel leak in system 1.

[0093] If no preliminary indications are given, device 3 determines that it cannot draw any conclusions about the presence or absence of a fuel leak in system 1. In such cases, this method is continued, that is, the measurement in step 180 is continued until the heat engine 2 is restarted, or if the measurement was stopped, it can be resumed. Thus, after the next shutdown of the vehicle's heat engine, the method, particularly from step 170 onward, is resumed for a new duration, for example, 6 hours or more. The more measurements taken within the time period, the higher the likelihood that the comparison steps performed will be able to draw a conclusion about the presence or absence of a fuel leak.

[0094] Prior to the steps described above, if the double valve 6 is configured differently from the configuration shown in Figure 1, the fuel leak detection method 100 assumes a step to return to the configuration shown in Figure 1, which is performed by a device 3 that 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, except when this method relates to the second test of method 400 described later.

[0095] This method 100 is not limited to the embodiments presented, and other embodiments will be obvious to those skilled in the art.

[0096] Thus, this method is applicable to any fuel system as defined at the beginning, and can be implemented in containers other than the fuel tank 4 and canister 5. In particular, it can be implemented in a standalone fuel tank 4 isolated from the canister 5, or in a standalone canister 5, or in any container in which a pressure sensor and a temperature sensor can be installed and connected to the data processing device 3.

[0097] II. Method for Identifying the Location of Fuel Leaks From here, we will explain the method 400 for locating fuel leaks in a fuel system, referring to Figure 4.

[0098] In step 410, the system 1 includes a fuel tank 4 and a canister 5 that are openly connected to each other, as shown in Figure 1, and the device 3 performs a first test to determine whether or not there is a fuel leak in the system 1, including the fuel tank 4 and the canister 5. This first test corresponds to method 100 described above. In other words, this method can detect whether or not there is a fuel leak in the subassembly formed from the fuel tank 4 and the canister 5.

[0099] In step 420, if the first test, i.e., method 100, determines that there is a fuel leak, the device 3 closes the connection between the fuel tank 4 and the canister 5 with the double valve 6 to isolate the two containers from each other. At this point, system 1 is configured as shown in Figure 2. The continuation of method 400 is performed on the system configured in this state.

[0100] In step 430-A, the device 3 immediately begins a second test to determine whether there is a fuel leak in the first container. Here, the same method as in method 100 is repeated, but steps 110 to 160 are omitted because the heat engine 2 is stopped. In other words, steps 170 onward are repeated until method 100 is stopped as described above. However, this time, the fuel tank 4, in which temperature and pressure measurements are taken, is isolated from the canister 5. In other words, fuel leak detection is limited to the fuel tank 4 only. This second test, performed immediately after the first test, includes the time in step 180, which continues until the heat engine 2 is restarted. In this step, the pressure and temperature measurements in the fuel tank 4 are taken at 30-minute intervals. Other time intervals may also be set. In other words, the number of time points changes depending on the duration and time intervals. Generally, the longer the duration, i.e., the longer the vehicle remains stopped, the higher the probability of detecting a fuel leak in the fuel tank 4 in this second test.

[0101] In the alternative step 430-B, this second test is pre-set to last 2 hours. This is a duration that generally allows for a sufficient number of measurements, i.e., a duration sufficient for the device 3 to conclude whether or not there is a fuel leak in the fuel tank 4. Thus, 2 hours for this second test are added to the 6 hours of the first test.

[0102] In the alternative step 430-C, the duration of the first test, performed when the connection between fuel tank 4 and canister 5 is open, is assumed to be set to 4 hours instead of 6 hours when combined with the second test. Adding the 2 hours of the second test brings the total duration of the first and second tests to 6 hours, providing a 6-hour method for detecting and, if applicable, locating fuel leaks, which optimizes the duration of the two tests while meeting CARB (California Air Resources Board) standards.

[0103] In the alternative step 430-D, the second test is not initiated immediately after the first test. That is, if a fuel leak is detected in the first test, this result is stored in memory by device 3. Subsequently, the vehicle's thermal engine is restarted by the driver, and the second test is initiated in the next cycle, i.e., the next shutdown of thermal engine 2, by closing the connection between fuel tank 4 and canister 5. In other words, if the shutdown of thermal engine 2 is considered the first shutdown, the second test is performed after the second shutdown of thermal engine 2, which occurs after the restart of thermal engine 2 following the first test. In this alternative, the measurement time in step 180 is preset to continue for 6 hours for this second test. That is, this second test is performed under the same conditions as the first test, thereby increasing the probability of concluding whether or not there is a fuel leak in fuel tank 4. Please note that in the second test, the connection between fuel tank 4 and canister 5 is assumed to be closed in both cases, and this connection may be reopened after the restart of heat engine 2.

[0104] In step 440, if the second test detects a fuel leak, the device 3 concludes that the fuel leak is located in the fuel tank 4; if the second test detects no fuel leak, the device 3 concludes that the fuel leak is located in the canister 5. In fact, since the first test already indicates that there is a leak in the subassembly formed by the fuel tank 4 and the canister 5, it is possible to determine whether the fuel leak is occurring in the fuel tank 4 or the canister 5 by closing the connection between the fuel tank 4 and the canister 5 and repeating method 100 for this second test.

[0105] If the device does not reach a conclusion after the second test, the following steps will be taken.

[0106] In step 450, if the second test fails to locate the fuel leak, device 3 performs the step of closing the connection between the fuel tank 4 and canister 5 of system 1 after the heat engine 2 is shut down following the restart of the heat engine that follows the second test, thereby isolating these two containers again. In fact, since the heat engine has been restarted, this connection may be open. In other words, after this step, the situation returns to that shown in Figure 2.

[0107] In step 460, the apparatus performs a third test to determine whether there is a fuel leak in the system's fuel tank 4 for a predetermined period of at least 6 hours. This third test is the same as the second test, i.e., method 100, excluding steps 110 through 160.

[0108] Thus, this third test is performed if the vehicle restarts before the predetermined time has elapsed, interrupting the second test, or if the device 3 is unable to locate the fuel leak. This extends the time for the next cycle, i.e., after the heat engine 2 has stopped again, to search for the leak by repeating steps 170 onward in a tank isolated from the outside.

[0109] Unless the location of the fuel leak is identified, the fourth, fifth, and other tests can be performed consecutively each time the heat engine 2 stops within the isolated fuel tank 4. Alternatively, these tests can be stopped. In particular, if the device 3 fails to identify the location of the fuel leak after performing several tests within the isolated fuel tank 4, the first test, namely the detection of a fuel leak in the subassembly formed by the fuel tank 4 and the canister 5, can be performed again.

[0110] It should be noted that all of these tests are passive, requiring neither suction generation or vacuuming of fuel system 1, nor any other mechanical operation on containers 4 and 5.

[0111] In this specification, - A first container and a second container connected to each other, namely the fuel tank 4 and the canister 5, - A shut-off valve 6 for the connection between the first container and the second container, - Apparatus 3 for carrying out the steps of Method 100 and Method 400 A vehicle fuel system 1 equipped with a heat engine 2 is also conceivable.

[0112] The present invention is not limited to the embodiments presented, and other embodiments will be obvious to those skilled in the art.

[0113] In particular, the present invention is not limited to the fuel tank 4 and canister 5, but can be implemented with any type of container that is connected to each other in an openable and closable manner.

[0114] Furthermore, instead of detection method 100, any fuel leak detection method in a container can be combined with method 400. In fact, the present invention assumes that the fuel leak detection method will be used at least twice to locate the leak, and in this respect the present invention is not limited to a specific fuel leak detection method. Also, the first test and the second test may not include the same fuel leak detection step.

[0115] Finally, note that a standard single valve of the "FTIV" type is sufficient to isolate the connection between tank 4 and canister 5, rather than a double valve 6. [Explanation of symbols]

[0116] 1. Fuel System 2. Vehicle heat engine 3. Data Processing Devices 4 Fuel tank 5 Canister 6 Double valve 7 Processors 8. Computer-readable recording media 9. Computer Programs 10 Temperature Sensor 11. Pressure sensor 12 Atmosphere 100 Method for determining whether or not there is a fuel leak 400 Method for locating fuel leaks

Claims

1. A method (400) for locating a fuel leak in a pressurized fuel system (1) of a vehicle equipped with a heat engine (2), comprising the following steps: - The system (1) includes a first container (4) and a second container (5) that are openly connected to each other, and the step of performing a first passive test (410) to determine whether or not there is a fuel leak in the system (1) including the first container (4) and the second container (5), - If a fuel leak is detected as a result of the first passive test (410), * The step (420) of closing the connection between the first container (4) and the second container (5) so as to isolate the two containers from each other, * A step of performing a second passive test (430) to determine whether or not there is a fuel leak in the first container (4), * If a fuel leak is detected as a result of the second passive test (430), the step (440) is to conclude that the location of the fuel leak is inside the first container (4), or if no fuel leak is detected as a result of the second test, the step (440) is to conclude that the location of the fuel leak is inside the second container (5). Includes, Method (400), wherein the first passive test and the second passive test are passive in that they do not require the generation of suction or vacuum of the fuel system (1) or any other mechanical operation on the first container (4) and the second container (5).

2. The first passive test (410) is, - A step (180) of measuring the respective pressure values ​​in the system (1) at predetermined different points in time within a certain period of time after the stopping (170) of the heat engine (2) of the vehicle, - A step (210) of determining the two time points in which the pressure values ​​are furthest apart from each other, - If the absolute value of the difference between these two pressure values ​​is less than or equal to a predetermined pressure difference threshold, the step (220) of concluding that there is a fuel leak in the system (1), and the step of stopping this method (100) The method according to claim 1 (400), including the method according to claim 1.

3. The first passive test (410) and the second passive test (430) for determining whether or not there is a fuel leak, - A step (180) of measuring the pressure and temperature values ​​in the first container of the system (1) at predetermined different time points within the first and second time periods, - A step of comparing at least one numerical value with a predetermined threshold (130, 150, 270, 290, 300, 330, 350) The method according to claim 1 (400), including the method according to claim 1.

4. The method according to any one of claims 1 to 3 (400), wherein the first passive test (410) is performed for a predetermined period of time, preferably at least 4 hours, and more particularly at least 6 hours, following the shutdown of the vehicle's heat engine (2).

5. The method according to claim 4 (400), wherein if a fuel leak is detected as a result of the first passive test (410), the second passive test is performed immediately after the completion of the first passive test (410) (430-A, 430-B, 430-C).

6. The method according to claim 5 (400), wherein the second passive test is continued for a predetermined time, preferably at least two hours (430-B, 430-C).

7. The method according to claim 5 (400), wherein the second passive test (430-A) is continued until the vehicle equipped with a heat engine is restarted.

8. The method according to any one of claims 1 to 4 (400), wherein the stopping of the heat engine (2) is defined as the first stopping, the second passive test (430-D) is performed after the restart of the heat engine (2) following the first passive test, and the second passive test is continued for a predetermined time, preferably at least 6 hours.

9. If the location of the fuel leak cannot be identified as a result of the second passive test, the following steps are taken after the second passive test, restarting the heat engine (2), stopping the heat engine (2), - Step (450) of closing the connection between the first container (4) and the second container (5) of the system so as to isolate the two containers from each other, - A step (460) of performing a third passive test to determine whether or not there is a fuel leak in the first container (4) of the system (1), which is continued for a predetermined time, preferably for at least six hours, wherein the third passive test is passive in that it does not require the generation of suction or vacuum of the fuel system (1) or any other mechanical operation on the first container (4) and the second container (5), and The method according to any one of claims 5 to 8 (400), including the method according to any one of claims 5 to 8.

10. The method according to any one of claims 1 to 9 (400), wherein the first container (4) of the system is a fuel tank, the second container (5) is a canister, and the opening and closing of the connection is operated by a valve (6).

11. A data processing device (3) comprising a processor (7) adapted to the steps of the method (400) according to any one of claims 1 to 10.

12. A fuel system (1) for a vehicle equipped with a heat engine (2), - A first container (4) and a second container (5) connected to each other, - The on / off valve (6) connecting the first container (4) and the second container (5), - Apparatus (3) according to claim 11 for carrying out the steps of the method described in any one of claims 1 to 10 in the system (1) and A fuel system (1) including the above.

13. A vehicle comprising a heat engine (2) including the fuel system (1) according to claim 12.

14. A computer program (9) that, when the program is executed by a computer, includes instructions causing the computer to perform the steps of the method (400) according to any one of claims 1 to 10.

15. A computer-readable recording medium (8) that includes instructions causing the computer to perform each of the steps of the method (400) according to any one of claims 1 to 10, when the instructions are performed by the computer.

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