A method for detecting a leak in a fuel vapor system and an electronic device

Abstract

The application provides a leakage detection method of a fuel evaporation system and an electronic device, and is applied to a fuel evaporation system of a vehicle. The method comprises the following steps: when the parking time of the vehicle exceeds a first preset time length, and the enabled working condition of the fuel evaporation system is normal, the vacuum degree of a first space in which a first electric control valve is in a closed state is obtained; a first diagnosis strategy or a second diagnosis strategy is selected according to the vacuum degree, and leakage detection is performed on the first space and a second space to obtain a detection result, wherein the first diagnosis strategy is a diagnosis strategy corresponding to that the first space has no leakage when the absolute value of the vacuum degree is greater than a first preset threshold. In this way, an air pump does not need to be additionally arranged, so that the hardware cost of the system is reduced. In addition, different diagnosis strategies are beneficial to improving the diagnosis completion rate. Since the first space of the fuel evaporation system rarely leaks, the frequency of using the first diagnosis strategy is usually high, and the detection process of the first diagnosis strategy is less, so that the diagnosis efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of fuel evaporation system technology, and more specifically, to a method and electronic device for detecting leaks in a fuel evaporation system. Background Technology

[0002] Currently, on-board diagnostic (OBD) systems in vehicles need to monitor leaks in the entire fuel evaporation system. Industry OEMs classify their solutions for diagnosing the fuel evaporation system of hybrid vehicles into two main categories based on their operating principles: post-operational diagnostics using DMTL (Diagnostic Module Tank Leakage) and inter-operational negative pressure vacuum diagnostics. Currently, both of these diagnostic solutions suffer from high hardware costs or low diagnostic completion rates (IUPR).

[0003] For example, patent CN114060163A discloses a DMTL pump diagnostic scheme. Its basic principle is that during vehicle operation after power-off, an air pump pressurizes the fuel evaporation system, causing the fuel tank pressure to rise. In the first stage, the air pump pumps air into a 0.5mm reference orifice, and the air pump drive current under leakage at the 0.5mm reference orifice is measured as a reference current. In the second stage, the air pump pumps air into the fuel tank, and the air pump drive current at this time is measured. Leakage is determined by comparing these two currents. The DMTL pump diagnostic scheme has significant advantages: high robustness, decoupling from vehicle operating conditions, and easy compliance with IUPR regulations. However, compared to conventional negative pressure diagnostic systems, the addition of an air pump results in a significant cost disadvantage, and post-operation diagnostics are not conducive to factory electrical testing of the vehicle.

[0004] Patent CN115111091A discloses a conventional diagnostic scheme for negative pressure vacuuming during operation. Its basic principle is that, under idling conditions, the engine creates a vacuum by opening the carbon canister solenoid valve and connecting it to the intake manifold. Once the required vacuum level is achieved, the carbon canister solenoid valve and the carbon canister ventilation shut-off valve are closed. In a sealed space, the rate at which the fuel evaporation system returns to normal pressure is monitored to determine the actual leakage amount. Compared to the aforementioned DMTL pump diagnostic scheme, this scheme has a significant cost advantage. However, due to the influence of gasoline sloshing within the fuel tank on the fuel tank vacuum level, its diagnostic operation must be performed at idle. For hybrid vehicles, considering fuel consumption and energy efficiency, the engine needs to be stopped when the vehicle is parked. This diagnostic scheme requires the engine to remain running at idle, creating a conflict between the diagnostic scheme and fuel consumption / energy efficiency strategies. Furthermore, since establishing a vacuum requires a certain amount of time, the diagnostic process is easily interrupted by vehicle operation (exiting idle), resulting in a lower overall IUPR rate. Summary of the Invention

[0005] In view of this, the purpose of this application is to provide a method and electronic device for detecting leaks in a fuel evaporation system, which can reduce the hardware cost of fuel leak detection and improve the diagnostic completion rate.

[0006] To achieve the above technical objectives, the technical solution adopted in this application is as follows:

[0007] In a first aspect, embodiments of this application provide a leak detection method for detecting a vehicle's fuel evaporation system. The fuel evaporation system includes a fuel tank and a carbon canister connected to the fuel tank. A second electrically controlled valve is installed on a connecting pipe between the carbon canister and the external environment. A first electrically controlled valve is installed on the connecting pipe between the carbon canister and the fuel tank. A third electrically controlled valve is installed on the connecting pipe between the carbon canister and an engine desorption model. The cavity formed by the fuel tank and the first electrically controlled valve is a first space, and the cavity formed by the carbon canister, the first electrically controlled valve, the second electrically controlled valve, and the third electrically controlled valve is a second space. The method includes:

[0008] When the vehicle is parked for a period of time exceeding the first preset time and the fuel evaporation system is in normal working condition, the vacuum level of the first space when the first electronic control valve is in the closed state is obtained.

[0009] Based on the vacuum level, a first diagnostic strategy or a second diagnostic strategy is selected to perform leak detection on the first space and the second space, and the detection result is obtained. The first diagnostic strategy is the diagnostic strategy corresponding to the first space having no leak when the absolute value of the vacuum level is greater than a first preset threshold.

[0010] In conjunction with the first aspect, in some optional embodiments, based on the vacuum level, a first diagnostic strategy or a second diagnostic strategy is selected to perform leak detection on the first space and the second space, obtaining the detection results, including:

[0011] When the absolute value of the vacuum degree is greater than the first preset threshold, the first diagnostic strategy is selected to perform leak detection on the first space and the second space, and the detection result is obtained;

[0012] When the absolute value of the vacuum degree is less than or equal to the first preset threshold, the second diagnostic strategy is selected to perform leak detection on the first space and the second space, and the detection result is obtained.

[0013] In conjunction with the first aspect, in some optional implementations, the first diagnostic strategy is selected to perform leak detection on the first space and the second space to obtain the detection results, including:

[0014] When the absolute value of the vacuum degree is greater than the first preset threshold, a detection result indicating that there is no leakage in the first space is obtained;

[0015] When the vehicle's engine is running, the carbon canister is desorbed, and when the fuel concentration in the carbon canister is lower than a preset concentration threshold, the first electronically controlled valve is opened to release pressure in the first space.

[0016] When the duration of the first electrically controlled valve being open exceeds the second preset duration, the second vacuum level of the first space or the second space is obtained;

[0017] When the absolute value of the difference between the second vacuum degree and the current ambient air pressure is greater than the second preset threshold, a detection result is obtained indicating that the second electronically controlled valve has a stuck normally closed fault.

[0018] When the absolute value of the difference between the second vacuum degree and the current ambient air pressure is less than or equal to the second preset threshold, a detection result is obtained indicating that the second solenoid valve does not have a stuck normally closed fault.

[0019] In conjunction with the first aspect, in some alternative implementations, the method further includes:

[0020] When the second solenoid valve does not have a stuck normally closed fault, the first solenoid valve is kept in the open state, the second solenoid valve and the third solenoid valve are closed, and the first flow rate of the carbon canister desorption in the first stage is counted.

[0021] When the first flow rate exceeds the first preset flow rate threshold and the vacuum degree of the oil tank exceeds the third preset threshold corresponding to the current oil level of the oil tank, a detection result indicating that the third electronically controlled valve has a leakage fault is obtained.

[0022] When the first flow rate exceeds the first preset flow rate threshold and the vacuum degree of the oil tank does not exceed the third preset threshold, a detection result indicating that the third electronically controlled valve does not have a leakage fault is obtained.

[0023] In conjunction with the first aspect, in some alternative implementations, the method further includes:

[0024] When the third solenoid valve does not have a leakage fault, the first solenoid valve and the third solenoid valve are both controlled to be in the open state, and the second solenoid valve is controlled to be in the closed state.

[0025] The second flow rate of the carbon canister during the second stage of desorption is statistically analyzed.

[0026] When the second flow rate exceeds the second preset flow rate threshold and the vacuum degree of the oil tank is less than the specified target vacuum degree, a detection result indicating that there is a large leakage fault in the second space is obtained;

[0027] When the second flow rate exceeds the second preset flow rate threshold and the vacuum degree of the oil tank is greater than or equal to the target vacuum degree, a detection result indicating that there is no major leakage fault in the second space is obtained.

[0028] In conjunction with the first aspect, in some alternative implementations, the method further includes:

[0029] When there is no major leakage fault in the second space, the first, second, and third solenoid valves are all kept in the closed state.

[0030] The vacuum level of the second space is sampled under pressure attenuation at a first preset period to obtain the first vacuum level dataset of the second space;

[0031] Based on the first vacuum degree dataset, the attenuation slope of the second space air pressure is obtained;

[0032] When the absolute value of the attenuation slope is less than the first preset slope, a detection result indicating that there is no small leakage in the second space is obtained;

[0033] When the absolute value of the attenuation slope is greater than or equal to the first preset slope, a detection result indicating that there is a small leak in the second space is obtained.

[0034] In conjunction with the first aspect, in some optional embodiments, when the absolute value of the vacuum degree is less than or equal to the first preset threshold, the second diagnostic strategy is selected to perform leak detection on the first space and the second space, and the detection result is obtained, including:

[0035] When the absolute value of the vacuum degree is less than or equal to the first preset threshold, wait for the engine to run in order to activate the desorption of the carbon canister;

[0036] When the concentration in the carbon canister is lower than a preset concentration threshold, the first electrically controlled valve is opened to release pressure in the first space.

[0037] When the second solenoid valve does not have a stuck normally closed fault and the third solenoid valve does not have a leakage fault, the first solenoid valve and the third solenoid valve are both controlled to be in the open state, and the second solenoid valve is controlled to be in the closed state.

[0038] The second flow rate of the carbon canister during the second stage of desorption is statistically analyzed.

[0039] When the second flow rate exceeds the second preset flow rate threshold and the vacuum degree of the oil tank is less than the specified target vacuum degree, a detection result indicating that there is a large leakage fault in the second space is obtained;

[0040] If the vacuum level of the fuel tank is greater than or equal to the target vacuum level before the second flow rate exceeds the second preset flow rate threshold, then a detection result indicating that there is no major leakage fault in the fuel evaporation system is obtained.

[0041] In conjunction with the first aspect, in some alternative implementations, the method further includes:

[0042] When there is no major leakage fault in the fuel evaporation system, the vehicle control system prevents the PCU from shutting down and waits for the vehicle to enter idle mode.

[0043] With a second preset period, pressure attenuation sampling is performed on the overall space formed by the first space and the second space to obtain a second vacuum degree dataset of the overall space. During the pressure holding period, if the vacuum degree of the oil tank is lower than the target vacuum degree, the third electronically controlled valve is controlled to open, and the first electronically controlled valve is controlled to be in the open state and the second electronically controlled valve is controlled to be in the closed state, so as to desorb the carbon canister.

[0044] Based on the second vacuum degree dataset, the attenuation slope of the overall space air pressure is obtained;

[0045] When the absolute value of the attenuation slope is less than the second preset slope, a detection result indicating that there is no small leakage in the overall space is obtained.

[0046] In conjunction with the first aspect, in some alternative implementations, the method further includes:

[0047] When the absolute value of the attenuation slope is greater than or equal to the second preset slope, both the first and second solenoid valves are opened to relieve pressure in the overall space.

[0048] When the vacuum level of the overall space decreases to the target vacuum level, both the second and third electrically controlled valves are closed.

[0049] The vacuum level of the entire space is collected at a third preset period to obtain a third vacuum level dataset;

[0050] Based on the third vacuum degree dataset, determine the fuel evaporation gradient within the overall space;

[0051] When the evaporation gradient is less than or equal to 0, the attenuation slope is obtained as an indication of the attenuation of the condensation phenomenon, and the detection result is obtained as an indication of a small leak in the overall space.

[0052] In conjunction with the first aspect, in some alternative implementations, the method further includes:

[0053] When the evaporation gradient is greater than 0, the attenuation slope is corrected according to the evaporation gradient to obtain the corrected attenuation slope;

[0054] If the absolute value of the corrected attenuation slope is greater than or equal to the second preset slope, a detection result indicating that there is a small leak in the overall space is obtained.

[0055] If the absolute value of the corrected attenuation slope is less than the second preset slope, then a detection result indicating that there is no small leakage in the overall space is obtained.

[0056] In conjunction with the first aspect, in some optional embodiments, the second preset slope is a threshold determined by looking up a pre-established second relationship table between oil level and slope threshold and the current oil level of the oil tank.

[0057] In conjunction with the first aspect, in some alternative implementations, the method further includes:

[0058] An alarm is issued when the detection results indicate that there is a leak in either the first space or the second space.

[0059] Thirdly, embodiments of this application also provide an electronic device, which includes a processor and a memory coupled to each other, wherein a computer program is stored in the memory, and when the computer program is executed by the processor, the electronic device performs the above-described method.

[0060] The invention employing the above technical solution has the following advantages:

[0061] In the technical solution provided in this application, during leak detection of the vehicle's fuel evaporation system, there is no need to pump air into the fuel evaporation system via an air pump, thus eliminating the need for an additional air pump and reducing system hardware costs. Furthermore, during detection, the vacuum level of the first space when the first electronically controlled valve is closed is obtained. Based on this vacuum level, a first diagnostic strategy or a second diagnostic strategy is selected to perform leak detection on both the first and second spaces, obtaining the detection result. The first diagnostic strategy is the strategy corresponding to the absence of leakage in the first space when the absolute value of the vacuum level is greater than a first preset threshold. Thus, different diagnostic strategies can be used to perform leak detection on the entire space of the fuel evaporation system based on whether the first space has no leakage or is suspected of leaking, thereby improving the diagnostic completion rate. Additionally, since the first space of the vehicle's fuel evaporation system typically does not leak, the first diagnostic strategy is usually used more frequently. Since using the first diagnostic strategy indicates that the first space does not leak, only the second space needs to be detected, resulting in fewer detection steps and faster detection speed, thus improving detection efficiency. Attached Figure Description

[0062] This application can be further illustrated by the non-limiting embodiments given in the accompanying drawings. It should be understood that the following drawings only illustrate some embodiments of this application and should not be considered as limiting the scope. For those skilled in the art, other related drawings can be obtained from these drawings without any inventive effort.

[0063] Figure 1 This is a flowchart illustrating the leakage detection method provided in an embodiment of this application.

[0064] Figure 2 This is a schematic diagram of the structure of the fuel evaporation system provided in an embodiment of this application.

[0065] Figure 3 This is a schematic diagram of the fault detection process provided in an embodiment of this application.

[0066] Figure 4 This is a schematic diagram of the flag fault management process provided in an embodiment of this application.

[0067] Icons: 10-Fuel evaporation system; 11-First electronic control valve; 12-Second electronic control valve; 13-Third electronic control valve; 14-Fuel tank; 15-Carbon canister; 16-First pressure sensor; 17-Second pressure sensor. Detailed Implementation

[0068] The present application will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that similar or identical parts are referred to by the same reference numerals in the drawings or description. Implementations not shown or described in the drawings are forms known to those skilled in the art. In the description of this application, terms such as "first" and "second" are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0069] Please refer to the reference. Figure 1 and Figure 2 This application provides a leak detection method for detecting whether a fuel evaporation system 10 of a vehicle is leaking. This method can be executed by an electronic device, which may include a processing module and a storage module. The storage module stores a computer program, which, when executed by the processing module, enables the electronic device to perform the corresponding steps in the leak detection method described below.

[0070] Please refer to Figure 2The fuel evaporation system 10 may include a fuel tank 14 and a carbon canister 15 connected to the fuel tank 14. A second electrically controlled valve 12 is installed on the connecting pipe between the carbon canister 15 and the external environment. A first electrically controlled valve 11 is installed on the connecting pipe between the carbon canister 15 and the fuel tank 14. A third electrically controlled valve 13 is installed on the connecting pipe between the carbon canister 15 and the engine desorption model. The fuel tank 14 is provided with a filler neck. The cavity formed by the fuel tank 14 and the first electrically controlled valve 11 is a first space, and the cavity formed by the carbon canister 15 and the first, second, and third electrically controlled valves 11 and 13 is a second space.

[0071] The engine desorption model can draw fuel gases from the carbon canister 15 into the engine. In the first space, a first pressure sensor 16 is installed in a pipe near the first electronically controlled valve 11 to detect the gas pressure in the fuel tank 14 / first space; in the second space, a second pressure sensor 17 is installed in a pipe near the first electronically controlled valve 11 to detect the gas pressure in the carbon canister 15 / second space. The first space is typically larger than the second space; therefore, the first space can be referred to as the large space, and the second space as the small space.

[0072] In this embodiment, the vehicle can be a hybrid vehicle that combines fuel with other power sources (such as electricity). The fuel tank 14 can be a high-pressure fuel tank. The first pressure sensor 16 can be a wide-range fuel tank pressure sensor, with a larger measurement range than a narrow-range fuel tank pressure sensor. The second pressure sensor 17 can be a narrow-range fuel tank pressure sensor, with higher accuracy than a wide-range fuel tank pressure sensor. The first electronically controlled valve 11 can be an FTIV valve (i.e., a high-pressure fuel tank flow control valve), the second electronically controlled valve 12 can be a Vent valve, and the third electronically controlled valve 13 can be a Purge valve. It should be noted that various pressure sensors and electronically controlled valves can be flexibly selected according to actual conditions, and no specific limitations are made here.

[0073] In this embodiment, the processing module of the electronic device can acquire the collected data from the first pressure sensor 16 and the second pressure sensor 17. Additionally, the processing module can independently control the opening or closing of the first electronically controlled valve 11, the second electronically controlled valve 12, and the third electronically controlled valve 13. This processing module can be an ECU (Electronic Control Unit) in the vehicle. The storage module can be integrated into the ECU or used as a separate electronic module to store first diagnostic strategies, second diagnostic strategies, and various thresholds (such as first preset thresholds and second preset thresholds). Of course, the storage module can also be used to store programs, which the processing module executes upon receiving an execution command.

[0074] Please refer to this again. Figure 1 Leak detection methods may include the following steps:

[0075] Step 110: When the vehicle's parking time exceeds the first preset time and the fuel evaporation system 10 is in normal working condition, obtain the vacuum level of the first space when the first electronic control valve 11 is in the closed state.

[0076] Step 120: Based on the vacuum level, select a first diagnostic strategy or a second diagnostic strategy to perform leak detection on the first space and the second space, and obtain the detection result. The first diagnostic strategy is the diagnostic strategy corresponding to the first space having no leak when the absolute value of the vacuum level is greater than a first preset threshold.

[0077] The steps of the leak detection method will be explained in detail below:

[0078] Prior to step 110, the method may further include an operational step of detecting whether the enabling condition of the fuel evaporation system 10 is normal. For example, prior to step 110, the method may further include:

[0079] The vehicle's EMS (Engine Management System) checks whether the following enabling conditions are met:

[0080] Condition 1: The vehicle ambient temperature and engine coolant temperature are within the preset temperature range (e.g., 4°C to 35°C).

[0081] Condition 2: The atmospheric pressure is higher than the specified atmospheric pressure (e.g., 72 kPa);

[0082] Condition 3: The battery voltage is within the specified voltage range (e.g., 11 to 16V);

[0083] Condition 4: The fuel level in the fuel tank is within the specified range (e.g., 15% to 85%).

[0084] Condition 5: The soaking time (hereinafter referred to as SoakTime) from the last parking to the start of the engine in this driving cycle exceeds the specified duration (e.g., 180 minutes);

[0085] Condition 6: EMS did not detect any of the following faults:

[0086] 1) Faulty drive stage and proper functioning of the first pressure sensor 16;

[0087] 2) Faulty drive stage and rationality of the first solenoid valve 11;

[0088] 3) Faulty drive stage and proper functioning of the second pressure sensor 17;

[0089] 4) Faulty drive stage and proper functioning of the second solenoid valve 12;

[0090] 5) Faulty drive stage and rationality of the third solenoid valve 13;

[0091] 6) Related faults of the carbon canister desorption model, including desorption pipeline detachment and gas leakage;

[0092] Among them, drive-level faults include short-circuit to power supply faults, short-circuit to ground faults, and open-circuit faults in sensors or drive components. Reasonableness faults include pin signal jamming, signal out-of-range, and unreasonable signal transitions in sensors or drive components.

[0093] If all the above conditions are met, it indicates that the fuel evaporation system 10 is operating normally and the leak diagnosis of the fuel evaporation system 10 is activated. If any condition is not met, the diagnostic enable condition judgment will be reset.

[0094] In step 110, the first preset duration can be flexibly determined according to the actual situation, for example, it can be 2 hours, 3 hours, etc. The electronic device can obtain the vacuum degree of the first space from the pressure data collected by the first pressure sensor 16 through the processing module. Understandably, under the same temperature and altitude, the greater the vacuum degree of the container, the lower the pressure inside the container and the thinner the gas inside the container; the lower the vacuum degree of the container, the greater the pressure inside the container and the denser the gas inside the container.

[0095] In this embodiment, step 120 may include:

[0096] Step 121: When the absolute value of the vacuum degree is greater than the first preset threshold, the first diagnostic strategy is selected to perform leak detection on the first space and the second space to obtain the detection result;

[0097] Step 122: When the absolute value of the vacuum degree is less than or equal to the first preset threshold, the second diagnostic strategy is selected to perform leak detection on the first space and the second space to obtain the detection result.

[0098] In step 120, the electronic device can select different diagnostic strategies for leak detection based on the difference in vacuum level in the first space. The first diagnostic strategy can be understood as FastPass logic, indicating that there is no leak in the first space, and only the second space needs to be detected for leaks. This reduces the number of detection steps and increases the detection speed. Since the first space of the fuel evaporation system 10 in a vehicle usually does not leak, the first diagnostic strategy is typically used more frequently. The first diagnostic strategy provided in this embodiment helps to improve detection efficiency.

[0099] Conversely, the second diagnostic strategy can be understood as a non-FastPass logic, indicating that there is a suspected leak in the first space, and a leak detection is required for both the first and second spaces as a whole. The detection process is more complex than that of the FastPass logic.

[0100] Specifically, in step 121, selecting the first diagnostic strategy to perform leak detection on the first space and the second space, and obtaining the detection result, may include:

[0101] When the absolute value of the vacuum degree is greater than the first preset threshold, a detection result indicating that there is no leakage in the first space is obtained;

[0102] When the vehicle's engine is running, the carbon canister 15 is desorbed, and when the fuel concentration in the carbon canister 15 is lower than a preset concentration threshold, the first electronically controlled valve 11 is opened to release pressure in the first space.

[0103] When the duration of the first electrically controlled valve 11 being open exceeds the second preset duration, the second vacuum level of the first space or the second space is obtained;

[0104] When the absolute value of the difference between the second vacuum degree and the current ambient air pressure is greater than the second preset threshold, a detection result is obtained indicating that the second solenoid valve 12 has a stuck normally closed fault.

[0105] When the absolute value of the difference between the second vacuum degree and the current ambient air pressure is less than or equal to the second preset threshold, a detection result is obtained indicating that the second solenoid valve 12 does not have a stuck normally closed fault.

[0106] In this embodiment, the desorption of the carbon canister 15 can be understood as follows: during engine operation, the third electronically controlled valve 13 is opened, so that the engine desorption model delivers the fuel adsorbed by the carbon canister 15 to the engine, thereby achieving the desorption of the carbon canister 15. Furthermore, the method for detecting the fuel concentration in the carbon canister 15 is a conventional method, which will not be described in detail here.

[0107] In this embodiment, each detection item involved in the fuel evaporation system 10 can be equipped with a flag bit. Upon completion of each detection, the flag bit for that item is set to a specified value. For example, please refer to... Figure 4If a stuck normally closed fault is detected in the second electronically controlled valve 12, the stuck normally closed fault flag of the second electronically controlled valve 12 will be set (VentClosedFailed = 1), and the fuel evaporation system 10 diagnostic completion flag will also be set (EVPDCmpt = 1), indicating that the testing process will be terminated. If no stuck normally closed fault is detected in the second electronically controlled valve 12, the diagnostic pass and diagnostic completion flags of the second electronically controlled valve 12 will be set (VentClosedPassed = 1, VentCloseCmpt = 1). Here, the flag setting can be understood as the corresponding flag being set to 1.

[0108] It should be noted that, in this embodiment, the various preset thresholds, preset durations, preset concentration thresholds, and the various preset flow rate thresholds corresponding to the vacuum level can all be flexibly set according to the actual situation.

[0109] If the second solenoid valve 12 has a stuck normally closed fault, the leakage detection process terminates. If the second solenoid valve 12 does not have a stuck normally closed fault, the leakage detection process continues. For example, based on the first diagnostic strategy, the method may also include:

[0110] When the second solenoid valve 12 does not have a stuck normally closed fault, the first solenoid valve 11 is kept in the open state, the second solenoid valve 12 and the third solenoid valve 13 are closed, and the first flow rate of the carbon canister 15 in the first stage of desorption is counted.

[0111] When the first flow rate exceeds the first preset flow rate threshold and the vacuum degree of the oil tank 14 exceeds the third preset threshold corresponding to the current oil level of the oil tank 14, a detection result indicating that the third electronically controlled valve 13 has a leakage fault is obtained.

[0112] When the first flow rate exceeds the first preset flow rate threshold and the vacuum degree of the oil tank 14 does not exceed the third preset threshold, a detection result indicating that the third electronically controlled valve 13 does not have a leakage fault is obtained.

[0113] In this embodiment, the first flow rate of the first stage of desorption can be obtained by integrating the flow rate. The integration calculation method is conventional and will not be described in detail here.

[0114] The third preset threshold corresponding to the current oil level in fuel tank 14 can be obtained by looking up a table. That is, a relationship table is pre-established to record different oil levels in fuel tank 14 and calibrated thresholds. The electronic device can collect the current oil level in fuel tank 14 and obtain the third preset threshold by looking up the relationship table based on the current oil level.

[0115] If the third solenoid valve 13 has a leakage fault, the leakage detection process terminates. If the third solenoid valve 13 does not have a leakage fault, the leakage detection process continues. For example, based on the first diagnostic strategy, the method may also include:

[0116] When there is no leakage fault in the third solenoid valve 13, the first solenoid valve 11 and the third solenoid valve 13 are both in the open state, and the second solenoid valve 12 is in the closed state.

[0117] The second flow rate of the carbon canister 15 during the second stage of desorption is statistically analyzed.

[0118] When the second flow rate exceeds the second preset flow rate threshold and the vacuum degree of the oil tank 14 is less than the specified target vacuum degree, a detection result indicating that there is a large leakage fault in the second space is obtained;

[0119] When the second flow rate exceeds the second preset flow rate threshold and the vacuum degree of the oil tank 14 is greater than or equal to the target vacuum degree, a detection result indicating that there is no major leakage fault in the second space is obtained.

[0120] In this embodiment, the calculation method for the second flow rate of the second stage desorption is similar to that of the first flow rate of the first stage, and will not be repeated here. The start time of both the first and second stages can be the moment when desorption begins on the carbon canister 15, the end time of the second stage is later than the time of the first stage, and the second preset flow rate threshold is greater than the first preset flow rate threshold.

[0121] If a major leak is found in the second space, the detection process will be terminated.

[0122] If no major leakage fault is found in the second space, the detection process continues. For example, based on the first diagnostic strategy, the method may also include:

[0123] When there is no major leakage fault in the second space, the first solenoid valve 11, the second solenoid valve 12 and the third solenoid valve 13 are all in the closed state.

[0124] The vacuum level of the second space is sampled under pressure attenuation at a first preset period to obtain the first vacuum level dataset of the second space;

[0125] Based on the first vacuum dataset, the attenuation slope of the air pressure in the second space is obtained. It should be noted that the pressure attenuation sampling and attenuation slope of the second space are independent of the vehicle's operating conditions. That is, leakage detection of the second space can be achieved whether the vehicle is driving or idling.

[0126] When the absolute value of the attenuation slope is less than the first preset slope, a detection result indicating that there is no small leak in the second space is obtained. The first preset slope is a threshold determined by looking up the table based on a first relationship table between temperature and slope threshold and the current temperature of the oil tank 14.

[0127] When the absolute value of the attenuation slope is greater than or equal to the first preset slope, a detection result indicating that there is a small leak in the second space is obtained, that is, the small leak diagnosis of the second space (small space) and the vehicle operating condition are decoupled.

[0128] In this embodiment, pressure attenuation sampling can be understood as follows: the first solenoid valve 11, the second solenoid valve 12 and the third solenoid valve 13 are all in the closed state so that the small space is in a relatively sealed state, and the pressure of the small space at different times is collected to obtain the vacuum degree of the small space.

[0129] The first vacuum degree dataset may include only two vacuum degree data, such as: the vacuum degree obtained in the small space after closing the first solenoid valve 11, the second solenoid valve 12 and the third solenoid valve 13, and another vacuum degree obtained in the small space after collecting the vacuum degree at a first preset interval.

[0130] In this embodiment, step 122, selecting the second diagnostic strategy to perform leak detection on the first space and the second space to obtain the detection result, may include:

[0131] When the absolute value of the vacuum degree is less than or equal to the first preset threshold, wait for the engine to run in order to activate the desorption of the carbon canister 15;

[0132] When the concentration of the carbon canister 15 is lower than a preset concentration threshold, the first electrically controlled valve 11 is opened to release pressure in the first space.

[0133] When the second solenoid valve 12 does not have a stuck normally closed fault and the third solenoid valve 13 does not have a leakage fault, the first solenoid valve 11 and the third solenoid valve 13 are both controlled to be in the open state, and the second solenoid valve 12 is controlled to be in the closed state.

[0134] The second flow rate of the carbon canister 15 during the second stage of desorption is statistically analyzed.

[0135] When the second flow rate exceeds the second preset flow rate threshold and the vacuum degree of the oil tank 14 is less than the specified target vacuum degree, a detection result indicating that there is a large leakage fault in the second space is obtained;

[0136] If the vacuum degree of the fuel tank 14 is greater than or equal to the target vacuum degree before the second flow rate exceeds the second preset flow rate threshold, then a detection result indicating that there is no major leakage fault in the fuel evaporation system 10 is obtained.

[0137] Understandably, during the leak detection using the second diagnostic strategy, the detection methods for the stuck normally closed fault of the second solenoid valve 12 and the leak fault of the third solenoid valve 13 can be found in the fault detection of the second solenoid valve 12 and the third solenoid valve 13 in the first diagnostic strategy, and will not be repeated here.

[0138] If there is a large leak in the fuel evaporation system 10, it means that there is a large leak in the overall space formed by the first space and the second space, and the testing process needs to be terminated.

[0139] If there is no major leak in the fuel evaporation system 10, the testing continues. For example, based on the second diagnostic strategy, the method may also include:

[0140] When there is no major leakage fault in the fuel evaporation system 10, the vehicle control prevents the PCU (Power Control Unit) from shutting down and waits for the vehicle to enter idle condition.

[0141] The pressure-holding decay sampling is performed on the overall space formed by the first space and the second space at a second preset period to obtain the second vacuum degree dataset of the overall space. During the pressure holding period, if the vacuum degree of the oil tank 14 is lower than the target vacuum degree, the third electric control valve 13 is controlled to open, and the first electric control valve 11 is controlled to be in the open state and the second electric control valve 12 is controlled to be in the closed state, so as to desorb the carbon canister 15.

[0142] Based on the second vacuum degree dataset, the attenuation slope of the overall space air pressure is obtained;

[0143] When the absolute value of the attenuation slope is less than the second preset slope, a detection result indicating that there is no small leakage in the overall space is obtained.

[0144] In this embodiment, the method for collecting the second vacuum degree dataset of the entire space is similar to the method for collecting the first vacuum degree dataset. Specifically, the electronic device can use the pressure value collected by the second pressure sensor 17 to calculate the vacuum degree of the entire space.

[0145] In this embodiment, the second preset slope is a threshold value determined by looking up a pre-established second relationship table between oil level and slope threshold and the current oil level of the oil tank 14. The second preset slope is related to the oil level of the oil tank 14, while the first preset slope is not related to the oil level.

[0146] If the absolute value of the attenuation slope is less than the second preset slope, the detection process will terminate, indicating that there is no small leakage in the overall space.

[0147] If the absolute value of the attenuation slope is greater than or equal to the second preset slope, it indicates that there is a suspected small leak in the overall space, requiring further detection, i.e., the detection process continues. For example, based on the second diagnostic strategy, the method may also include:

[0148] When the absolute value of the attenuation slope is greater than or equal to the second preset slope, the first solenoid valve 11 and the second solenoid valve 12 are both opened to relieve pressure on the overall space.

[0149] When the vacuum level of the overall space decreases to the target vacuum level, the second solenoid valve 12 and the third solenoid valve 13 are both closed.

[0150] The vacuum level of the entire space is collected at a third preset period to obtain a third vacuum level dataset;

[0151] Based on the third vacuum degree dataset, determine the fuel evaporation gradient within the overall space;

[0152] When the evaporation gradient is less than or equal to 0, the attenuation slope is obtained as an indication of the attenuation of the condensation phenomenon, and the detection result is obtained as an indication of a small leak in the overall space.

[0153] Understandably, if the evaporation gradient is less than or equal to 0, it indicates that the condensation phenomenon in the entire fuel evaporation system is more severe. To mitigate the decrease in vacuum due to the condensation phenomenon, the detection process is terminated.

[0154] If the evaporation gradient is greater than 0, it indicates that the evaporation phenomenon in the entire fuel evaporation system 10 is more intense. Gasoline evaporation will exacerbate the vacuum decay, requiring correction of the decay slope; that is, the detection process continues. For example, based on the second diagnostic strategy, the method may also include:

[0155] When the evaporation gradient is greater than 0, the attenuation slope is corrected according to the evaporation gradient to obtain the corrected attenuation slope;

[0156] If the absolute value of the corrected attenuation slope is greater than or equal to the second preset slope, a detection result indicating that there is a small leak in the overall space is obtained.

[0157] If the absolute value of the corrected attenuation slope is less than the second preset slope, then a detection result indicating that there is no small leakage in the overall space is obtained.

[0158] As an optional implementation, the method may further include:

[0159] An alarm is issued when the detection results indicate that there is a leak in either the first space or the second space.

[0160] In this embodiment, the alarm notification helps vehicle owners to detect leakage faults in a timely manner.

[0161] Please refer to the reference. Figure 2 , Figure 3 and Figure 4 To facilitate understanding, the implementation process of two diagnostic strategies will be illustrated below with examples. The first diagnostic strategy corresponds to scenario one, and the second diagnostic strategy corresponds to scenario two. Examples are as follows:

[0162] By default, the first solenoid valve 11 is closed, the second solenoid valve 12 is open, and the third solenoid valve 13 is closed.

[0163] Keep the first electronically controlled valve 11 normally closed, and use the wide-range oil tank pressure sensor 1 to determine the vacuum level of the oil tank 14 in the large space to decide on different diagnostic strategy application scenarios.

[0164] Scene 1:

[0165] If the absolute value of the vacuum in fuel tank 14 exceeds the calibrated first preset threshold (e.g., 4 kPa), it indicates that the vehicle's fuel evaporation system 10 can build up pressure normally. At this point, EMS considers the large space leak-free and the large space diagnostic is completed quickly (FastPass). Then, it waits for the engine to run to activate the charcoal canister desorption.

[0166] Furthermore, EMS only needs to perform leak diagnosis on small spaces; when the concentration of charcoal in the canister is lower than the calibrated preset concentration threshold (e.g., 20%), the first electronically controlled valve 11 is opened to depressurize the large space.

[0167] Furthermore, if the duration of opening the first electronically controlled valve 11 exceeds the second preset duration (e.g., 20 seconds), and the absolute value of the difference between the vacuum level in the entire space (connected to the small space) and the current ambient atmospheric pressure is still greater than the calibrated second preset threshold (e.g., 0.5 kPa), it indicates that the second electronically controlled valve 12 has a stuck normally closed fault. The stuck normally closed fault flag of the second electronically controlled valve 12 is set (VentClosedFailed = 1), and the diagnostic completion flag of the fuel evaporation system 10 will also be set (EVPDCmpt = 1). Otherwise, when the vacuum level in the fuel tank 14 can be normally reduced to atmospheric pressure, the diagnostic pass and diagnostic completion flags of the second electronically controlled valve 12 are set (VentClosedPassed = 1, VentCloseCmpt = 1), and the second electronically controlled valve 12 is closed. At this time, the first electronically controlled valve 11 remains open, the third electronically controlled valve 13 is closed, and a leak diagnosis is performed on the third electronically controlled valve 13. The desorption flow rate integration of the first stage carbon canister 15 begins to obtain the total flow rate in the first stage, which is used as the first flow rate.

[0168] Furthermore, when the first flow rate of the virtual desorption flow integral in the first stage exceeds the calibrated first preset flow rate threshold (e.g., 5000 grams), and the vacuum degree in the fuel tank 14 exceeds the calibrated third preset threshold (obtained from a table based on the current fuel level), it is considered that the third electronic control valve 13 has a leakage fault. The leakage diagnosis fault flag and diagnosis completion flag of the third electronic control valve 13 are set (PurgeFailed = 1, PurgeCmpt = 1), and the diagnosis completion flag of the entire fuel evaporation system 10 will also be set (EVPDCmpt = 1).

[0169] When the first flow rate of the virtual desorption flow integral in the first stage exceeds the calibrated first preset flow rate threshold (e.g., 5000 grams), and the vacuum degree in the oil tank 14 does not exceed the calibrated third preset threshold, the leakage test of the third electronic control valve 13 is passed and the completion flag is set (PurgePassed=1, PurgeCmpt=1).

[0170] Furthermore, after PurgePassed = 1 (i.e., there is no leakage fault in the third electronic control valve 13), the second electronic control valve 12 remains closed, the first electronic control valve 11 is opened, the third electronic control valve 13 is opened, the entire fuel evaporation system 10 is desorbed, the second stage of carbon canister desorption flow integration begins, and the calculated total flow is used as the second flow.

[0171] Furthermore, if the second flow rate obtained by integrating the desorption flow rate of the carbon canister exceeds the second preset flow rate threshold (e.g., 20,000 grams), and the target vacuum level (e.g., 2.55 kPa) still cannot be established in the fuel tank 14, then a large leak fault is considered to exist in the entire space. The large leak fault diagnosis flag and the diagnosis completion flag are set (LrgLeakFailed = 1, LrgLeakCmpt = 1), and the diagnosis completion flag of the entire fuel evaporation system 10 will also be set (EVPDCmpt = 1).

[0172] When the vacuum level of the entire space reaches the target vacuum level (e.g., 2.55 kPa) before the desorption flow integral in the second stage reaches the second preset flow threshold, it is considered that there is no large leakage fault in the small space, and the large leakage test pass flag is set (LrgLeakPassed = 1, LrgLeakCmpt = 1). Keep the second electronic control valve 12 closed, and immediately close the first electronic control valve 11 and the third electronic control valve 13 to perform a small leakage test in the small space. The EMS starts to sample the pressure attenuation of the small space area. The vacuum level of the small space is not affected by oil sloshing, so the leakage diagnosis of the small space can be performed under driving conditions to avoid affecting the PCU shutdown.

[0173] Furthermore, during the pressure holding phase, when the vacuum level of the small space decays to the target vacuum level P1 (e.g., 2.5 kPa) for calculating the slope, or after closing the first solenoid valve 11, the second solenoid valve 12, and the third solenoid valve 13, the sampling start time is recorded as t1. The pressure holding vacuum level P2 at the end of the sampling is recorded. In this embodiment, the sampling interval (first preset period) can be 5 seconds. The decay slope of the small space is obtained as Slope = (P1 - P2) / t1.

[0174] Furthermore, fault diagnosis is performed on the decay slope of the small space. When the absolute value of the decay slope is less than the calibrated first preset slope, it is considered that there is no small leak in the small space, and the small space small leak diagnosis pass flag and diagnosis completion flag are set (SmleakPassed=1, SmleakCmpt=1); when the decay slope exceeds the first preset slope, it is considered that there is a small leak in the small space, and the small space small leak diagnosis fault flag and diagnosis completion flag are set (SmleakFailed=1, SmleakCmpt=1), and the entire fuel evaporation system 10 diagnosis completion flag will also be set (EVPDCmpt=1).

[0175] It should be noted that, due to the isolation effect of the first electronically controlled valve 11, the leakage slope of the small space is no longer affected by the oil sloshing and oil volume in the oil tank 14. The threshold for the attenuation slope test only considers the influence of ambient temperature; therefore, the small leakage attenuation threshold (first preset slope) is obtained by looking up a table based on the ambient temperature.

[0176] For example, the rows of a table could be arrays based on ambient temperature. Example: Ambient temperature [0, 10, 15, 25, 35], in °C.

[0177] The vertical cell corresponding to each temperature value records the threshold of vacuum decay slope of a 1mm standard leak hole at different temperatures.

[0178] The slope threshold can be calibrated in an environmental chamber by measuring the leakage of 1mm standard holes of different vehicles under different ambient temperatures and analyzing their discrete distribution characteristics.

[0179] Furthermore, after the small space leak diagnosis is completed, the second electronic control valve 12 and the first electronic control valve 11 are opened, and the third electronic control valve 13 is closed to depressurize the entire fuel evaporation system 10. The fuel evaporation system 10 diagnosis completion flag is set (EVPDCmpt=1).

[0180] Scene 2:

[0181] If the absolute value of the vacuum in fuel tank 14 is less than the first preset threshold (e.g., 4 kPa), and the vehicle's fuel evaporation system 10 fails to build up pressure naturally after a certain period of rest, it indicates a possible leak in the large space. The large space diagnostic cannot be FastPassed, and a leak diagnosis of the entire fuel evaporation system 10 is required. Then, wait for the engine to run to activate the charcoal canister desorption.

[0182] Furthermore, the EMS performs leak diagnosis for both large and small spaces. When the concentration in the charcoal canister falls below a preset concentration threshold (20%), the first electrically controlled valve 11 is opened to depressurize the large space.

[0183] Furthermore, the fault diagnosis strategy for the stuck normally closed second solenoid valve 12 is the same as in scenario one; the leakage diagnosis strategy for the third solenoid valve 13 is the same as in scenario one.

[0184] Furthermore, after PurgePassed = 1 (indicating that there is no leakage fault in the third electronic control valve 13), the second electronic control valve 12 remains closed, the first electronic control valve 11 is opened, the third electronic control valve 13 is opened, the entire fuel evaporation system 10 is desorbed, and the second stage of carbon canister desorption flow integration begins.

[0185] Furthermore, if the total flow rate obtained by integrating the second-stage carbon canister desorption flow rate exceeds the second preset flow rate threshold (e.g., 20,000 grams), and the target vacuum level (e.g., 2.55 kPa) still cannot be established in the fuel tank 14, then a large leak fault is considered to exist in the small space. The large leak diagnosis fault flag and diagnosis completion flag are set (LrgLeakFailed = 1, LrgLeakCmpt = 1), and the diagnosis completion flag of the entire fuel evaporation system 10 will also be set (EVPDCmpt = 1). When the vacuum level of the entire system reaches the target vacuum level (2.55 kPa) before the second-stage desorption flow rate integration reaches the second preset flow rate threshold, then a large leak fault is considered to exist in the entire space, and the large leak test pass and completion flags are set (LrgLeakPassed = 1, LrgLeakCmpt = 1). During the test, to prevent over-vacuuming of the fuel tank 14, the third electronic control valve 13 needs to be closed immediately after the target vacuum level is established.

[0186] Furthermore, after LrgLeakPassed = 1 (indicating no major leakage in the entire space), the EMS prevents the PCU from shutting down and waits for the vehicle to enter idle condition to conduct a small leakage test of the entire space. The EMS then begins to sample the pressure attenuation of the entire space. During this process, if the vacuum level of the fuel tank 14 decreases below the target vacuum level, the third electronic control valve 13 needs to be reopened to enable charcoal canister desorption. Throughout the process, the second electronic control valve 12 remains closed and the first electronic control valve 11 remains open.

[0187] Furthermore, during the pressure holding phase, when the vacuum level of the entire space decays to the target vacuum level P1 (e.g., 2.5 kPa) for calculating the slope, the sampling start time t2 is recorded, and the pressure holding vacuum level P2 at the end of the sampling is recorded. In this embodiment, the sampling interval can be 10 s. The decay slope of the entire space is then obtained as Slope = (P1 - P2) / t2.

[0188] Furthermore, fault diagnosis is performed on the slope of the entire space. When the slope is less than the calibrated second preset slope, it is considered that there is no small leak in the entire space, and the small leak diagnosis is performed through the flag bit and the diagnosis completion flag bit (SmleakPassed=1, SmleakCmpt=1); when the slope exceeds the second preset slope, it is necessary to confirm whether the increased vacuum slope is caused by excessive fuel evaporation in the fuel tank 14.

[0189] Furthermore, when the attenuation slope exceeds the second preset slope, the second solenoid valve 123 is opened to depressurize the entire system. When the system vacuum level drops to the target vacuum level (e.g., 0.5 kPa), the second solenoid valve 12 and the third solenoid valve 13 are closed, and the vacuum level change within the sampling time t3 (5 s) is recorded simultaneously. The initial vacuum level P3 and the vacuum level P4 at the end of the sampling are also recorded. The evaporation gradient VG = (P3 - P4) / t3.

[0190] When the evaporation gradient is negative, it indicates that the condensation phenomenon in the entire fuel evaporation system 10 is more intense. The condensation phenomenon slows down the decay of vacuum, so there is no need to correct the decay slope of the entire space. At this time, the small leak diagnosis fault flag and the diagnosis completion flag are set (SmleakFailed=1, SmleakCmpt=1), and the diagnosis completion flag of the entire fuel evaporation system 10 will also be set (EVPDCmpt=1).

[0191] When the evaporation gradient is positive, it indicates that the evaporation phenomenon in the entire fuel evaporation system 10 is more intense, and gasoline evaporation will exacerbate the vacuum decay. Therefore, the slope needs to be corrected using the evaporation gradient. If the corrected slope Slope1 = (Slope - VG) still exceeds the calibration threshold, it indicates that a small leak has occurred. The small leak diagnosis fault flag and diagnosis completion flag are set (SmleakFailed = 1, SmleakCmpt = 1), and the diagnosis completion flag for the entire fuel evaporation system 10 will also be set (EVPDCmpt = 1). When the corrected slope Slope1 is less than the calibration threshold, it indicates that the small leak in the entire system has not reached the leak failure standard. The small leak diagnosis pass and diagnosis completion flags are set (SmleakPassed = 1, SmleakCmpt = 1), and the diagnosis completion flag for the entire fuel evaporation system 10 will also be set (EVPDCmpt = 1).

[0192] It should be noted that, since the vacuum level of the entire space is affected by the oil level, the failure threshold for small leaks (the second preset slope) is obtained by looking up a table based on the oil level. That is, a table relating different oil levels to slope thresholds is pre-established, and the corresponding second preset slope can be obtained by looking up the table based on the current oil level.

[0193] The relationship table records the threshold of vacuum attenuation slope of a 1mm standard leak hole at different oil levels.

[0194] This relationship table can be calibrated in the environmental chamber. It is obtained by measuring the leakage of 1mm standard orifice of different vehicles at different oil levels and analyzing its discrete distribution characteristics.

[0195] Furthermore, after the small leak diagnosis of the entire space is completed, the second electronic control valve 12 and the first electronic control valve 11 are opened, and the third electronic control valve 13 is closed to depressurize the entire fuel evaporation system 10. The fuel evaporation system 10 diagnosis completion flag is set (EVPDCmpt=1).

[0196] During the entire diagnostic process, when EVPDCmpt=1 is detected, the diagnosis of the fuel evaporation system 10 will be stopped, and the EMS will control the second electronic control valve 12 and the third electronic control valve 13 to restore their original states, thus completing the entire diagnostic process.

[0197] The vehicle's EMS will collect the diagnostic test results and, through the OBD (On-Board Diagnostics) calibration strategy, decide whether to report relevant fault codes and illuminate the malfunction indicator lamp.

[0198] Based on the above design, it facilitates electrical testing after the factory line is completed. Compared with conventional negative pressure diagnostic solutions, the method provided by this invention can effectively solve the conflict problem of not being able to stop at idle speed, shorten the diagnostic completion time, and improve the IUPR rate.

[0199] It should be noted that those skilled in the art will understand that, for the sake of convenience and brevity, the specific working process of the electronic device described above can be referred to the corresponding steps in the aforementioned method, and will not be elaborated further here.

[0200] In the embodiments provided in this application, it should be understood that the disclosed devices and methods can also be implemented in other ways. The device and method embodiments described above are merely illustrative. For example, the flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of this application. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code, which includes one or more executable instructions for implementing a specified logical function. It should also be noted that each block in a block diagram and / or flowchart, and combinations of blocks in block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system that performs the specified function or action, or using a combination of dedicated hardware and computer instructions. Furthermore, the functional modules in the various embodiments of this application can be integrated together to form an independent part, or each module can exist independently, or two or more modules can be integrated to form an independent part.

[0201] The above description is merely an embodiment of this application and is not intended to limit the scope of protection of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A leak detection method, characterized in that, A method for detecting a vehicle's fuel evaporation system includes a fuel tank, a carbon canister connected to the fuel tank, a second electrically controlled valve installed on a connecting pipe between the carbon canister and the external environment, a first electrically controlled valve installed on a connecting pipe between the carbon canister and the fuel tank, and a third electrically controlled valve installed on a connecting pipe between the carbon canister and an engine desorption model. The cavity formed by the fuel tank and the first electrically controlled valve is a first space, and the cavity formed by the carbon canister and the first, second, and third electrically controlled valves is a second space. The method includes: When the vehicle is parked for a period of time exceeding the first preset time and the fuel evaporation system is in normal working condition, the vacuum level of the first space when the first electronic control valve is in the closed state is obtained. Based on the vacuum level, a first diagnostic strategy or a second diagnostic strategy is selected to perform leak detection on the first space and the second space, and the detection result is obtained. The first diagnostic strategy is the diagnostic strategy corresponding to the first space having no leak when the absolute value of the vacuum level is greater than a first preset threshold. Based on the vacuum level, a first diagnostic strategy or a second diagnostic strategy is selected to perform leak detection on the first space and the second space, and the detection results are obtained, including: When the absolute value of the vacuum degree is greater than the first preset threshold, the first diagnostic strategy is selected to perform leak detection on the first space and the second space, and the detection result is obtained; When the absolute value of the vacuum degree is less than or equal to the first preset threshold, the second diagnostic strategy is selected to perform leak detection on the first space and the second space to obtain the detection result; Selecting the first diagnostic strategy to perform leak detection on the first space and the second space, and obtaining the detection results, includes: When the absolute value of the vacuum degree is greater than the first preset threshold, a detection result indicating that there is no leakage in the first space is obtained; When the vehicle's engine is running, the carbon canister is desorbed, and when the fuel concentration in the carbon canister is lower than a preset concentration threshold, the first electronically controlled valve is opened to release pressure in the first space. When the duration of the first electrically controlled valve being open exceeds the second preset duration, the second vacuum level of the first space or the second space is obtained; When the absolute value of the difference between the second vacuum degree and the current ambient air pressure is greater than the second preset threshold, a detection result is obtained indicating that the second electronically controlled valve has a stuck normally closed fault. When the absolute value of the difference between the second vacuum degree and the current ambient air pressure is less than or equal to the second preset threshold, a detection result is obtained indicating that the second electronically controlled valve does not have a stuck normally closed fault. When the absolute value of the vacuum level is less than or equal to the first preset threshold, the second diagnostic strategy is selected to perform leak detection on the first space and the second space, and the detection result is obtained, including: When the absolute value of the vacuum degree is less than or equal to the first preset threshold, wait for the engine to run in order to activate the desorption of the carbon canister; When the concentration in the carbon canister is lower than a preset concentration threshold, the first electrically controlled valve is opened to release pressure in the first space. When the second solenoid valve does not have a stuck normally closed fault and the third solenoid valve does not have a leakage fault, the first solenoid valve and the third solenoid valve are both controlled to be in the open state, and the second solenoid valve is controlled to be in the closed state. The second flow rate of the carbon canister during the second stage of desorption is statistically analyzed. When the second flow rate exceeds the second preset flow rate threshold and the vacuum degree of the oil tank is less than the specified target vacuum degree, a detection result indicating that there is a large leakage fault in the second space is obtained; If the vacuum degree of the fuel tank is greater than or equal to the target vacuum degree before the second flow rate exceeds the second preset flow rate threshold, then a detection result indicating that there is no major leakage fault in the fuel evaporation system is obtained; By default, the first solenoid valve is closed, the second solenoid valve is open, and the third solenoid valve is closed.

2. The method according to claim 1, characterized in that, The method further includes: When the second solenoid valve does not have a stuck normally closed fault, the first solenoid valve is kept in the open state, the second solenoid valve and the third solenoid valve are closed, and the first flow rate of the carbon canister desorption in the first stage is counted. When the first flow rate exceeds the first preset flow rate threshold and the vacuum degree of the oil tank exceeds the third preset threshold corresponding to the current oil level of the oil tank, a detection result indicating that the third electronically controlled valve has a leakage fault is obtained. When the first flow rate exceeds the first preset flow rate threshold and the vacuum degree of the oil tank does not exceed the third preset threshold, a detection result indicating that the third electronically controlled valve does not have a leakage fault is obtained.

3. The method according to claim 2, characterized in that, The method further includes: When the third solenoid valve does not have a leakage fault, the first solenoid valve and the third solenoid valve are both controlled to be in the open state, and the second solenoid valve is controlled to be in the closed state. The second flow rate of the carbon canister during the second stage of desorption is statistically analyzed. When the second flow rate exceeds the second preset flow rate threshold and the vacuum degree of the oil tank is less than the specified target vacuum degree, a detection result indicating that there is a large leakage fault in the second space is obtained; When the second flow rate exceeds the second preset flow rate threshold and the vacuum degree of the oil tank is greater than or equal to the target vacuum degree, a detection result indicating that there is no major leakage fault in the second space is obtained.

4. The method according to claim 3, characterized in that, The method further includes: When there is no major leakage fault in the second space, the first, second, and third solenoid valves are all kept in the closed state. The vacuum level of the second space is sampled under pressure attenuation at a first preset period to obtain the first vacuum level dataset of the second space; Based on the first vacuum degree dataset, the attenuation slope of the second space air pressure is obtained; When the absolute value of the attenuation slope is less than the first preset slope, a detection result indicating that there is no small leak in the second space is obtained. The first preset slope is a threshold determined by looking up the table based on a pre-established first relationship table between temperature and slope threshold and the current temperature of the oil tank. When the absolute value of the attenuation slope is greater than or equal to the first preset slope, a detection result indicating that there is a small leak in the second space is obtained.

5. The method according to claim 1, characterized in that, The method further includes: When there is no major leakage fault in the fuel evaporation system, the vehicle control system prevents the PCU from shutting down and waits for the vehicle to enter idle mode. With a second preset period, pressure attenuation sampling is performed on the overall space formed by the first space and the second space to obtain a second vacuum degree dataset of the overall space. During the pressure holding period, if the vacuum degree of the oil tank is lower than the target vacuum degree, the third electronically controlled valve is controlled to open, and the first electronically controlled valve is controlled to be in the open state and the second electronically controlled valve is controlled to be in the closed state, so as to desorb the carbon canister. Based on the second vacuum degree dataset, the attenuation slope of the overall space air pressure is obtained; When the absolute value of the attenuation slope is less than the second preset slope, a detection result indicating that there is no small leakage in the overall space is obtained.

6. The method according to claim 5, characterized in that, The method further includes: When the absolute value of the attenuation slope is greater than or equal to the second preset slope, both the first and second solenoid valves are opened to relieve pressure in the overall space. When the vacuum level of the overall space decreases to the target vacuum level, both the second and third electrically controlled valves are closed. The vacuum level of the entire space is collected at a third preset period to obtain a third vacuum level dataset; Based on the third vacuum degree dataset, determine the fuel evaporation gradient within the overall space; When the evaporation gradient is less than or equal to 0, the attenuation slope is obtained as an indication of the attenuation of the condensation phenomenon, and the detection result is obtained as an indication of a small leak in the overall space.

7. The method according to claim 6, characterized in that, The method further includes: When the evaporation gradient is greater than 0, the attenuation slope is corrected according to the evaporation gradient to obtain the corrected attenuation slope; If the absolute value of the corrected attenuation slope is greater than or equal to the second preset slope, a detection result indicating that there is a small leak in the overall space is obtained. If the absolute value of the corrected attenuation slope is less than the second preset slope, then a detection result indicating that there is no small leakage in the overall space is obtained.

8. The method according to claim 5, characterized in that, The second preset slope is a threshold determined by looking up a pre-established second relationship table between oil level and slope threshold and the current oil level in the tank.

9. The method according to claim 1, characterized in that, The method further includes: An alarm is issued when the detection results indicate that there is a leak in either the first space or the second space.

10. An electronic device, characterized in that, The electronic device includes a processor and a memory coupled together, the memory storing a computer program that, when executed by the processor, causes the electronic device to perform the method as described in any one of claims 1-9.

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