A method for detecting leakage of fuel system

Abstract

The present application discloses a method for detecting leakage of a fuel system, including: when the vehicle leakage detection conditions are met, adjusting the pressure of the fuel system so that the pressure of the fuel tank reaches a first pressure; controlling the fuel system to enter a pressure-maintaining state, the pressure-maintaining time is a first preset time, and detecting the pressure of the fuel tank at the end of the pressure-maintaining as a second pressure; adjusting the pressure of the fuel system so that the pressure of the fuel tank returns to atmospheric pressure; controlling the fuel system to enter a pressure-maintaining state, the pressure-maintaining time is a first preset time, and detecting the pressure of the fuel tank at the end of the pressure-maintaining as a third pressure; calculating the difference between the first pressure and the second pressure as a first difference, and calculating the sum of the first difference and the third pressure as a first sum; judging whether the first sum is within the standard range; if so, judging that the leakage detection is qualified. The present application takes into account the vapor pressure generated by fuel evaporation in the leakage detection to improve the accuracy of the detection.

Description

Technical Field

[0001] The present application relates to the field of vehicle technology, and more specifically, to a method for detecting leakage of a fuel system. Background Art

[0002] With the tightening of laws and regulations in various countries and the strengthening of environmental awareness, governments and OEMs have higher and higher requirements for vehicle emissions. Currently, more and more vehicles are designed with fuel system leakage detection modules, which can perform cumulative micro-hole leakage detection on the entire fuel system, thereby preventing the leakage of fuel or fuel vapor in the fuel system and ensuring the sealing of the fuel system, thereby saving fuel, protecting the environment and ensuring vehicle safety.

[0003] At present, the main leakage detection method is to use the leakage hole (also called reference hole) set on the leakage detection module to determine the standard value of the pressure change of the fuel system, and use the standard value of the pressure change as a reference value to evaluate the leakage of the fuel system.

[0004] However, due to the volatility of fuel, the pressure measured during the pressure measurement process includes the vapor pressure generated by the evaporation of fuel, so the judgment result of the leak detection is inaccurate. Summary of the invention

[0005] The present application provides a fuel system leakage detection method, which takes the vapor pressure generated by fuel evaporation into account during the leakage detection process to improve the accuracy of the detection result.

[0006] The present application provides a fuel system leakage detection method, comprising:

[0007] When the vehicle leakage detection conditions are met, the pressure of the fuel system is adjusted so that the pressure of the fuel tank reaches a first pressure;

[0008] Controlling the fuel system to enter a pressure-maintaining state, the pressure-maintaining time being a first preset time, and detecting the pressure of the fuel tank at the end of the pressure-maintaining state as a second pressure;

[0009] Regulate the pressure of the fuel system so that the pressure in the fuel tank returns to atmospheric pressure;

[0010] Controlling the fuel system to enter a pressure-maintaining state, the pressure-maintaining time being a first preset time, and detecting the pressure of the fuel tank at the end of the pressure-maintaining state as a third pressure;

[0011] Calculating a difference between the first pressure and the second pressure as a first difference, and calculating a sum of the first difference and the third pressure as a first sum;

[0012] Determine whether the first sum is within the standard range;

[0013] If yes, the leakage test is considered qualified.

[0014] Preferably, adjusting the pressure of the fuel system so that the pressure of the fuel tank reaches the first pressure specifically includes:

[0015] Detect the absolute pressure of the fuel tank as the fourth pressure;

[0016] determining whether the fourth pressure is less than the first pressure;

[0017] If so, the fuel system is controlled to be pressurized to the first pressure.

[0018] Preferably, if the fourth pressure is greater than the first pressure, the fuel system is controlled to release pressure to the first pressure.

[0019] Preferably, controlling the fuel system to release pressure to a first pressure specifically includes:

[0020] The fuel tank isolation valve and the carbon canister solenoid valve on the first branch of the leakage detection module are controlled to open, so that the steam in the fuel tank enters the atmosphere through the fuel tank isolation valve, the carbon canister and the first branch until the pressure of the fuel tank reaches the first pressure and the carbon canister solenoid valve is closed.

[0021] Preferably, controlling the fuel system to be pressurized to a first pressure specifically includes:

[0022] Control the carbon canister solenoid valve on the first branch of the leakage detection module to close;

[0023] Control the fuel tank isolation valve and the air pump on the second branch of the leakage detection module to open, so that gas enters the fuel tank from the atmosphere through the second branch of the leakage detection module, the carbon canister, and the fuel tank isolation valve until the air pump is turned off when the pressure of the fuel tank reaches the first pressure.

[0024] Preferably, a one-way valve is provided on the second branch of the leakage detection module, and the one-way valve allows the atmosphere to enter the oil tank.

[0025] Preferably, adjusting the pressure of the fuel system so that the pressure of the fuel tank returns to atmospheric pressure specifically includes:

[0026] The fuel tank isolation valve and the carbon canister solenoid valve on the first branch of the leakage detection module are controlled to open, so that the steam in the fuel tank enters the atmosphere through the fuel tank isolation valve, the carbon canister and the first branch until the pressure of the fuel tank reaches atmospheric pressure and the carbon canister solenoid valve is closed.

[0027] Preferably, if the pressure of the fuel tank is lower than the first pressure when the time for pressurizing the fuel system exceeds the second preset time, the leakage test fails;

[0028] The second preset time is greater than the third preset time, and the third preset time is the normal time length required to pressurize from the fourth pressure to the first pressure.

[0029] Preferably, if the fourth pressure is greater than the first pressure, the fuel system is controlled to enter a pressure-maintaining state, the pressure-maintaining time is a sixth preset time, and the pressure of the fuel tank at the end of the pressure-maintaining is detected as the seventh pressure;

[0030] calculating a difference between the fourth pressure and the seventh pressure as a third difference;

[0031] Determining whether the third difference is within a threshold range;

[0032] If yes, the leakage test is considered qualified.

[0033] The present application also provides a fuel system leakage detection method, comprising:

[0034] When the vehicle leakage test conditions are met, adjust the pressure of the fuel system so that the pressure of the fuel tank reaches atmospheric pressure;

[0035] Controlling the fuel system to enter a pressure-maintaining state, the pressure-maintaining time being a fourth preset time, and detecting the pressure of the fuel tank during the pressure-maintaining process;

[0036] Regulate the pressure of the fuel system so that the pressure in the fuel tank returns to atmospheric pressure;

[0037] adjusting the pressure of the fuel system so that the pressure of the fuel tank reaches a first pressure, the first pressure being greater than the atmospheric pressure;

[0038] Controlling the fuel system to enter a pressure-maintaining state, the pressure-maintaining time being a fifth preset time, and detecting the pressure of the fuel tank at the end of the pressure-maintaining state as a fifth pressure;

[0039] Acquire a pressure value corresponding to a fifth preset time from the pressure values ​​obtained during the atmospheric pressure maintaining process as a sixth pressure;

[0040] calculating a difference between the first pressure and the fifth pressure as a second difference, and calculating a sum of the second difference and the sixth pressure as a second sum;

[0041] Determine whether the second sum is within the standard range;

[0042] If yes, the leakage test is considered qualified.

[0043] Preferably, when the vehicle leakage detection conditions are met, the pressure of the fuel system is adjusted so that before the pressure of the fuel tank reaches the atmospheric pressure, the absolute pressure of the fuel tank is detected as the ninth pressure;

[0044] If the ninth pressure is greater than the first pressure, the fuel system is controlled to enter a pressure-maintaining state, the pressure-maintaining time is the sixth preset time, and the pressure of the fuel tank at the end of the pressure-maintaining is detected as the tenth pressure;

[0045] calculating a difference between the ninth pressure and the tenth pressure as a fourth difference;

[0046] determining whether the fourth difference is within a threshold range;

[0047] If yes, the leakage test is considered qualified.

[0048] Other features and advantages of the present application will become apparent from the following detailed description of exemplary embodiments of the present application with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the application and, together with the description, serve to explain the principles of the application.

[0050] Figure 1 It is a flow chart of a first embodiment of a method for detecting leakage of a fuel system provided by the present application;

[0051] Figure 2 is with Figure 1 Corresponding pressure timing diagram;

[0052] Figure 3 is a flow chart of a second embodiment of a fuel system leakage detection method provided by the present application;

[0053] Figure 4 is with Figure 3 Corresponding pressure timing diagram;

[0054] Figure 5 It is a structural schematic diagram of an embodiment of a fuel system provided by the present application;

[0055] Figure 6 yes Figure 5 A schematic structural diagram of a leakage detection module in an embodiment of the present invention;

[0056] Figure 7 It is a structural schematic diagram of an embodiment of a fuel system leakage detection device provided by the present application;

[0057] Figure 8 It is a structural schematic diagram of another embodiment of the fuel system leakage detection device provided in the present application. DETAILED DESCRIPTION

[0058] Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that unless otherwise specifically stated, the relative arrangement of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present application.

[0059] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the present application, its application, or uses.

[0060] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered part of the specification.

[0061] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0062] Embodiment 1

[0063] As an example, combining Figure 1 and 2 As shown, the fuel system leakage detection method provided by the present application includes:

[0064] S110: When the vehicle leakage detection conditions are met, the pressure of the fuel system is adjusted so that the pressure of the fuel tank reaches a first pressure P1, and the first pressure is greater than the atmospheric pressure.

[0065] Specifically, adjusting the pressure of the fuel system so that the pressure of the fuel tank reaches the first pressure P1 specifically includes:

[0066] S1101: Detect the absolute pressure of the fuel tank as the fourth pressure.

[0067] S1102: Determine whether the fourth pressure is greater than the first pressure P1. Figure 2 If the fourth pressure is less than the first pressure P1 (such as P4 in the example shown), S1103 is executed; Figure 2 P4′ in the example shown), then execute S1104.

[0068] It can be understood that the fourth pressure is between 0-P1.

[0069] S1103: Control the fuel system to release pressure to the first pressure P1, such as Figure 2 As shown, the time taken to release the pressure from the fourth pressure P4 to the first pressure P1 is t2.

[0070] S1104: Control the fuel system to pressurize to the first pressure P1, such as Figure 2 As shown, the time taken to increase the pressure from the fourth pressure P4' to the first pressure P1 is t1.

[0071] Preferably, if the pressure of the fuel tank is still lower than the first pressure P1 when the time for pressurizing the fuel system exceeds the second preset time, the leakage test is determined to be unqualified. The second preset time is much longer than the third preset time, and the third preset time is the normal time length required for pressurizing from the fourth pressure to the first pressure.

[0072] S120: Control the fuel system to enter a pressure-maintaining state, the pressure-maintaining time is a first preset time, and detect the pressure of the fuel tank at the end of the pressure-maintaining state as the second pressure P2. Figure 2 As shown, the holding time is t3.

[0073] S130: Adjust the pressure of the fuel system so that the pressure of the fuel tank returns to the atmospheric pressure P0. Figure 2 As shown, the pressure on the horizontal axis is the atmospheric pressure P0, and the time it takes for the pressure of the oil tank to recover from the second pressure P2 to the atmospheric pressure P0 is t4.

[0074] S140: Control the fuel system to enter a pressure-maintaining state, and the pressure-maintaining time is a first preset time ( Figure 2 The pressure of the oil tank at the end of the pressure maintenance is detected as the third pressure P3.

[0075] S150: Calculate the difference between the first pressure P1 and the second pressure P2 as the first difference D1, and calculate the sum of the first difference and the third pressure P3 as the first sum S1.

[0076] S160: Determine whether the first sum S1 is within the standard range. If so, execute S170; otherwise, execute S180.

[0077] S170: Determine whether the leakage test is qualified and output the determination result.

[0078] S180: Determine that the leakage test is unqualified and output the determination result.

[0079] S190: After the leakage test is completed, the pressure of the fuel system is adjusted so that the pressure of the fuel tank returns to the atmospheric pressure P0. Figure 2 As shown, the time it takes for the pressure of the oil tank to recover from the third pressure P3 to the atmospheric pressure P0 is t5.

[0080] Preferably, in step S1102, if the fourth pressure is greater than the first pressure P1, the fuel system is controlled to enter a pressure-maintaining state, the pressure-maintaining time is a sixth preset time, and the pressure of the fuel tank at the end of the pressure-maintaining is detected as the seventh pressure; then the difference between the fourth pressure and the seventh pressure is calculated as the third difference; it is determined whether the third difference is within a threshold range; if so, it is directly determined that the leakage test is qualified, without the need to release the pressure to the first pressure and then perform leakage detection and subsequent pressure compensation steps.

[0081] As another example, combining Figure 3 and 4 As shown, the leakage detection methods include:

[0082] S310: When the vehicle leakage detection conditions are met, the pressure of the fuel system is adjusted so that the pressure of the fuel tank reaches the atmospheric pressure P0.

[0083] Specifically, the pressure of the fuel system is adjusted so that the pressure of the fuel tank reaches the atmospheric pressure P0, which specifically includes:

[0084] S3101: Detect the absolute pressure of the fuel tank as the ninth pressure.

[0085] S3102: Determine whether the ninth pressure is greater than the atmospheric pressure P0. Figure 4 P9 in the example shown), then execute S3103; if the ninth pressure is less than the atmospheric pressure P0 ( Figure 4 ), execute S3104.

[0086] S3103: Control the fuel system to release pressure to atmospheric pressure P0, such as Figure 4 As shown, the time taken to release the pressure from the ninth pressure P9 to the atmospheric pressure P0 is t6.

[0087] S3104: Control the fuel system to pressurize to atmospheric pressure P0.

[0088] S320: Control the fuel system to enter a pressure-maintaining state, the pressure-maintaining time is a fourth preset time, and detect the pressure of the fuel tank during the pressure-maintaining process. Figure 4 As shown, the fourth preset time is t7, and the pressure at the end of pressure maintenance is the eighth pressure P8.

[0089] S330: Adjust the pressure of the fuel system so that the pressure of the fuel tank returns to the atmospheric pressure P0. Figure 4 As shown, the time taken for the eighth pressure P8 to recover to the atmospheric pressure P0 is t8.

[0090] S340: Regulate the pressure of the fuel system so that the pressure of the fuel tank reaches a first pressure P1, and the first pressure P1 is greater than the atmospheric pressure P0. Figure 4 As shown, the time taken to pressurize from the atmospheric pressure P0 to the first pressure P1 is t9.

[0091] Preferably, if the pressure of the fuel tank is still lower than the first pressure P1 when the fuel system is pressurized for more than an eighth preset time, the leakage test is determined to be unqualified. The eighth preset time is much longer than the seventh preset time, which is the normal time required to pressurize from atmospheric pressure to the first pressure.

[0092] S350: Control the fuel system to enter a pressure-maintaining state, the pressure-maintaining time is the fifth preset time, and detect the pressure of the fuel tank at the end of the pressure-maintaining state as the fifth pressure P5. The fifth preset time is less than the fourth preset time. Figure 4 As shown, the holding time is t10.

[0093] S360: Obtain the pressure value corresponding to the fifth preset time from the pressure values ​​obtained during the atmospheric pressure maintenance process as the sixth pressure P6, such as Figure 4 shown.

[0094] S370: Calculate the difference between the first pressure P1 and the fifth pressure P5 as the second difference D2, and calculate the sum of the second difference D2 and the sixth pressure P6 as the second sum S2.

[0095] S380: Determine whether the second sum S2 is within the standard range. If so, execute S390; otherwise, execute S3100.

[0096] S390: Determine whether the leakage test is qualified and output the judgment result.

[0097] S3100: Determine that the leakage test is unqualified and output the judgment result.

[0098] S3110: After the leakage test is completed, adjust the pressure of the fuel system so that the pressure of the fuel tank returns to the atmospheric pressure P0. Figure 4 As shown, the time taken to release the pressure from the fifth pressure to the atmospheric pressure is t11.

[0099] Preferably, in step S3102, if the ninth pressure is greater than the first pressure P1, the fuel system is controlled to enter a pressure-maintaining state, the pressure-maintaining time is the ninth preset time, and the pressure of the fuel tank at the end of the pressure-maintaining is detected as the tenth pressure; then the difference between the ninth pressure and the tenth pressure is calculated as the fourth difference; it is determined whether the fourth difference is within the threshold range; if so, it is directly determined that the leakage test is qualified without the need for subsequent pressure compensation and leakage detection steps at the first pressure.

[0100] According to the Antoine equation: log 10 P=AB / (TC), the vapor pressure P generated by the liquid is related to the parameters A, B, C of the medium, and also to the ambient temperature T at that time.

[0101] Since fuel is volatile, under the same conditions, fuel volatilization will generate a certain pressure. Under the condition of a certain detection time, the vapor pressure generated by fuel volatilization can be detected within the same time by maintaining the pressure, and then the pressure generated by the vapor can be subtracted from the pressure difference obtained by the leak detection, so as to correct the pressure difference and eliminate the interference of the pressure generated by fuel volatilization on the leak detection.

[0102] It should be noted that, since the fuel system maintains pressure for a short time at the first pressure, the fuel volatilization characteristics are not affected by conditions such as temperature. Therefore, the pressure generated by the volatilization of the fuel at atmospheric pressure is the same as the pressure generated by the volatilization of the fuel at the first pressure.

[0103] In this embodiment, since the pressure generated by fuel volatilization cannot be directly detected in the first pressure maintaining state, the pressure generated by fuel volatilization under atmospheric pressure is used to assist in determining the pressure generated by fuel system leakage, thereby improving the accuracy of leakage detection.

[0104] At the same time, this embodiment uses a leakage detection module to replace the existing reference hole, thereby preventing the leakage detection result from being affected by the production accuracy and detection accuracy of the reference hole.

[0105] Specifically, as an embodiment, a fuel system matching the above leakage detection method is as follows: Figure 5 and 6 As shown, the fuel system includes a fuel tank 1, a fuel tank isolation valve 2, a carbon canister 3, a leakage detection module 4 and an air filter 5 which are connected in sequence. A pipeline 11 is provided between the fuel tank 1 and the fuel tank isolation valve 2, a pipeline 12 is provided between the fuel tank isolation valve 2 and the carbon canister 3, a pipeline 13 is provided between the carbon canister 3 and the leakage detection module 4, a pipeline 14 is provided between the leakage detection module 4 and the air filter 5, and the air filter 5 is connected to the atmosphere 6 through a pipeline 15. The carbon canister 3 is connected to the desorption solenoid valve 9 through a pipeline 16, and the desorption solenoid valve 9 is connected to the engine 10 through a pipeline 17.

[0106] like Figure 5 and 6 As shown, the leakage detection module 4 includes a controller 8 and a detection component, the detection component includes a first branch 25 and a second branch 24 connected in parallel, the first branch 25 includes a carbon canister solenoid valve 22, the second branch 24 includes a pressure regulator and a one-way valve 23, the pressure regulator includes an air pump 20 and a motor 21 driving the air pump 20, and the one-way valve 23 allows the atmosphere to enter the fuel tank 1.

[0107] It should be noted that during the leakage detection process, the desorption solenoid valve 9 remains closed.

[0108] Based on the above fuel system, in steps S1103 and S3103, controlling the fuel system to release pressure to the first pressure P1 or the atmospheric pressure P0 specifically includes:

[0109] The carbon canister solenoid valve 22 on the first branch 25 of the control fuel tank isolation valve 2 and the leakage detection module 4 is opened (it can be understood that if the fuel tank isolation valve 2 is in an open state, the control fuel tank isolation valve 2 is maintained in this state), so that the steam in the fuel tank 1 enters the atmosphere through the fuel tank isolation valve 2, the carbon canister 3, the first branch 25 and the air filter 5 until the pressure of the fuel tank 1 reaches the first pressure P1 or the atmospheric pressure P0, and then the carbon canister solenoid valve 22 is closed.

[0110] In steps S1104, S340 and S3104, controlling the fuel system to be pressurized to the first pressure P1 or the atmospheric pressure P0 specifically includes:

[0111] The carbon canister solenoid valve 22 on the first branch 25 of the leakage detection module 4 is controlled to be closed (it can be understood that if the carbon canister solenoid valve 22 is in a closed state, the carbon canister solenoid valve 22 is controlled to maintain this state); the fuel tank isolation valve 2 and the air pump 20 on the second branch 24 of the leakage detection module 4 are controlled to be opened (it can be understood that if the fuel tank isolation valve 2 is in an open state, the fuel tank isolation valve 2 is controlled to maintain this state), so that the gas enters the fuel tank 1 from the atmosphere 6 through the air filter 5, the second branch 24 of the leakage detection module 4, the carbon canister 3, and the fuel tank isolation valve 2, until the pressure of the fuel tank 1 reaches the first pressure P1 or the atmospheric pressure P0, and then the air pump 20 is turned off.

[0112] In this embodiment, the pressure relief and pressurization gas circuits are independent of each other, and which gas circuit is used to reach the first pressure is determined based on the relationship between the absolute pressure in the fuel tank and the first pressure in the initial state, so that the pressure of the fuel system is more stable and the convenience of operation is improved.

[0113] In steps S120, S140, S320 and S350, when the canister solenoid valve 22 and the air pump 20 are closed, the fuel system enters a pressure-maintaining state.

[0114] In steps S130, S190, S330 and S3110, the pressure of the fuel system is adjusted so that the pressure of the fuel tank returns to the atmospheric pressure P0, which specifically includes:

[0115] The carbon canister solenoid valve 22 on the first branch 25 of the control fuel tank isolation valve 2 and the leakage detection module 4 is opened (it can be understood that if the fuel tank isolation valve 2 is in an open state, the control fuel tank isolation valve 2 is maintained in this state), so that the steam in the fuel tank 1 enters the atmosphere 6 through the fuel tank isolation valve 2, the carbon canister 3, the first branch 25 and the air filter 5 until the pressure of the fuel tank 1 reaches the atmospheric pressure P0 and the carbon canister solenoid valve 22 is closed.

[0116] Embodiment 2

[0117] Based on the above-mentioned fuel system leakage detection method, the present application provides a fuel system leakage detection device. As an embodiment, Figure 7 As shown, the leakage detection device includes a first regulating module 710 , a first pressure maintaining module 720 , a second regulating module 730 , a second pressure maintaining module 740 , a first calculating module 750 , a first judging module 760 , and a first output module 770 .

[0118] The first regulating module 710 is used to regulate the pressure of the fuel system so that the pressure of the fuel tank reaches a first pressure.

[0119] The first pressure-maintaining module 720 is used to control the fuel system to enter a pressure-maintaining state, the pressure-maintaining time is a first preset time, and detects the pressure of the fuel tank at the end of the pressure-maintaining state as the second pressure.

[0120] The second regulating module 730 is used to regulate the pressure of the fuel system so that the pressure of the fuel tank returns to atmospheric pressure.

[0121] The second pressure-maintaining module 740 is used to control the fuel system to enter a pressure-maintaining state, the pressure-maintaining time is a first preset time, and detects the pressure of the fuel tank at the end of the pressure-maintaining state as the third pressure.

[0122] The first sum calculation module 750 is used to calculate the difference between the first pressure and the second pressure as the first difference, and calculate the sum of the first difference and the third pressure as the first sum.

[0123] The first judging module 760 is used to judge whether the first sum is within a standard range.

[0124] The first output module 770 is used to output a test result indicating that the leakage test is qualified if the first sum is within the standard range, or to output a test result indicating that the leakage test is unqualified if the first sum is not within the standard range.

[0125] Specifically, Figure 7 As shown, the first adjustment module 710 includes a pressure detection module 7101, a second judgment module 7102 and a third adjustment module 7103;

[0126] The pressure detection module 7101 is used to detect the absolute pressure of the fuel tank as the fourth pressure.

[0127] The second determination module 7102 is used to determine whether the fourth pressure is greater than the first pressure.

[0128] The third regulating module 7103 is used to control the fuel system to release pressure to the first pressure if the fourth pressure is greater than the first pressure; or to control the fuel system to pressurize to the first pressure if the fourth pressure is less than the first pressure.

[0129] As another example, Figure 8 As shown, the leakage detection device includes a fourth adjustment module 810, a third pressure maintaining module 820, a fifth adjustment module 830, a fourth pressure maintaining module 840, a pressure acquisition module 850, a second calculation module 860, a third judgment module 870, and a second output module 880.

[0130] The fourth regulating module 810 is used to regulate the pressure of the fuel system so that the pressure of the fuel tank reaches atmospheric pressure.

[0131] The third pressure-maintaining module 820 is used to control the fuel system to enter a pressure-maintaining state, the pressure-maintaining time is a fourth preset time, and detect the pressure of the fuel tank during the pressure-maintaining process.

[0132] The fifth regulating module 830 is used to regulate the pressure of the fuel system so that the pressure of the fuel tank returns to atmospheric pressure, and then regulate the pressure of the fuel system so that the pressure of the fuel tank reaches the first pressure.

[0133] The fourth pressure-maintaining module 840 is used to control the fuel system to enter a pressure-maintaining state, the pressure-maintaining time is a fifth preset time, and detects the pressure of the fuel tank at the end of the pressure-maintaining state as the fifth pressure.

[0134] The pressure acquisition module 850 is used to acquire a pressure value corresponding to the fifth preset time from the pressure values ​​obtained during the atmospheric pressure maintenance process as the sixth pressure.

[0135] The second sum calculation module 860 is used to calculate the difference between the first pressure and the fifth pressure as the second difference, and calculate the sum of the second difference and the sixth pressure as the second sum.

[0136] The third judgment module 870 is used to judge whether the second sum is within a standard range.

[0137] The second output module 880 is used to output a test result indicating that the leakage test is qualified if the second sum is within the standard range, or to output a test result indicating that the leakage test is unqualified if the second sum is not within the standard range.

[0138] The fuel system leakage detection method and device provided in the present application take the vapor pressure generated by fuel evaporation into consideration during the leakage detection process, thereby improving the accuracy of the judgment result.

[0139] Although some specific embodiments of the present application have been described in detail by way of example, it should be understood by those skilled in the art that the above examples are only for illustration, not for limiting the scope of the present application. It should be understood by those skilled in the art that the above embodiments may be modified without departing from the scope and spirit of the present application. The scope of the present application is defined by the appended claims.

Claims

1. A method for detecting leakage of a fuel system, characterized in that: include: When the vehicle leakage detection conditions are met, the pressure of the fuel system is adjusted so that the pressure of the fuel tank reaches a first pressure; Controlling the fuel system to enter a pressure-maintaining state, the pressure-maintaining time being a first preset time, and detecting the pressure of the fuel tank at the end of the pressure-maintaining state as a second pressure; adjusting the pressure of the fuel system so that the pressure of the fuel tank returns to atmospheric pressure; Controlling the fuel system to enter a pressure-maintaining state, the pressure-maintaining time being the first preset time, and detecting the pressure of the fuel tank at the end of the pressure-maintaining state as a third pressure; calculating a difference between the first pressure and the second pressure as a first difference, and calculating a sum of the first difference and the third pressure as a first sum; determining whether the first sum is within a standard range; If yes, the leakage test is considered qualified; The step of adjusting the pressure of the fuel system so that the pressure of the fuel tank reaches the first pressure specifically includes: Detect the absolute pressure of the fuel tank as the fourth pressure; determining whether the fourth pressure is less than the first pressure; If the fourth pressure is greater than the first pressure, the fuel system is controlled to enter a pressure-maintaining state for a sixth preset time, and the pressure of the fuel tank at the end of the pressure-maintaining state is detected as a seventh pressure; calculating a difference between the fourth pressure and the seventh pressure as a third difference; Determining whether the third difference is within a threshold range; If so, it is determined that the leakage test is qualified; otherwise, the fuel system is controlled to release pressure to the first pressure.

2. The method for detecting leakage of a fuel system according to claim 1, characterized in that: If the fourth pressure is lower than the first pressure, the fuel system is controlled to be pressurized to the first pressure.

3. The method for detecting leakage of a fuel system according to claim 1, characterized in that: Controlling the fuel system to release pressure to the first pressure specifically includes: The fuel tank isolation valve and the carbon canister solenoid valve on the first branch of the leakage detection module are controlled to open, so that the steam in the fuel tank enters the atmosphere through the fuel tank isolation valve, the carbon canister, and the first branch, until the pressure of the fuel tank reaches the first pressure and the carbon canister solenoid valve is closed.

4. The method for detecting leakage of a fuel system according to claim 2, characterized in that: Controlling the fuel system to pressurize to the first pressure specifically includes: Control the carbon canister solenoid valve on the first branch of the leakage detection module to close; Control the oil tank isolation valve and the air pump on the second branch of the leakage detection module to open, so that gas enters the oil tank from the atmosphere through the second branch of the leakage detection module, the carbon canister, and the oil tank isolation valve until the pressure of the oil tank reaches the first pressure and the air pump is turned off.

5. The method for detecting leakage of a fuel system according to claim 4, characterized in that: A one-way valve is provided on the second branch of the leakage detection module, and the one-way valve allows the atmosphere to enter the oil tank.

6. The method for detecting leakage of a fuel system according to claim 1, characterized in that: Regulating the pressure of the fuel system so that the pressure of the fuel tank returns to atmospheric pressure specifically includes: The fuel tank isolation valve and the carbon canister solenoid valve on the first branch of the leakage detection module are controlled to open, so that the steam in the fuel tank enters the atmosphere through the fuel tank isolation valve, the carbon canister, and the first branch until the pressure of the fuel tank reaches atmospheric pressure and the carbon canister solenoid valve is closed.

7. The method for detecting leakage of a fuel system according to claim 2 or 4, characterized in that: If the pressure of the fuel tank is lower than the first pressure when the time for pressurizing the fuel system exceeds the second preset time, the leakage detection fails; The second preset time is greater than the third preset time, and the third preset time is the normal time length required to pressurize from the fourth pressure to the first pressure.

8. A method for detecting leakage of a fuel system, characterized in that: include: When the vehicle leakage test conditions are met, adjust the pressure of the fuel system so that the pressure of the fuel tank reaches atmospheric pressure; Controlling the fuel system to enter a pressure-maintaining state, the pressure-maintaining time being a fourth preset time, and detecting the pressure of the fuel tank during the pressure-maintaining process; Regulate the pressure of the fuel system so that the pressure in the fuel tank returns to atmospheric pressure; adjusting the pressure of the fuel system so that the pressure of the fuel tank reaches a first pressure, wherein the first pressure is greater than the atmospheric pressure; Controlling the fuel system to enter a pressure-maintaining state, the pressure-maintaining time being a fifth preset time, and detecting the pressure of the fuel tank at the end of the pressure-maintaining state as a fifth pressure; Acquire a pressure value corresponding to the fifth preset time from the pressure values ​​obtained during the atmospheric pressure maintaining process as a sixth pressure; calculating a difference between the first pressure and the fifth pressure as a second difference, and calculating a sum of the second difference and the sixth pressure as a second sum; determining whether the second sum is within a standard range; If yes, the leakage test is considered qualified; Wherein, the leakage detection method further comprises: When the vehicle leakage test conditions are met, the fuel system pressure is adjusted so that the absolute pressure of the fuel tank is tested before the pressure of the fuel tank reaches the atmospheric pressure, which is used as the ninth pressure; If the ninth pressure is greater than the first pressure, the fuel system is controlled to enter a pressure-maintaining state for a sixth preset time, and the pressure of the fuel tank at the end of the pressure-maintaining state is detected as a tenth pressure; calculating a difference between the ninth pressure and the tenth pressure as a fourth difference; Determining whether the fourth difference is within a threshold range; If so, the leakage test is deemed qualified; otherwise, the pressure of the fuel system is adjusted so that the pressure of the fuel tank reaches atmospheric pressure.

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