Leakage diagnosis method of fuel evaporation system and related equipment

Abstract

The invention discloses a leakage diagnosis method of a fuel evaporation system and related equipment, relates to the technical field of automobile electronic control, and mainly aims to solve the problem that a traditional leakage attenuation diagnosis method of the fuel evaporation system is extremely easy to cause fault misinformation. The method comprises the steps that basic parameters of the fuel evaporation system in the vacuumizing stage are obtained, the fuel evaporation system meets the requirement that the sealing and desorption capacity of a carbon canister electromagnetic valve reaches the standard, and the basic parameters comprise the initial pressure, the end pressure, a pressure change curve and a liquid level correction coefficient; calculating gas loss mass based on the basic parameters; a leakage aperture is calculated based on the gas loss mass and the basic parameters, and the leakage aperture is used for diagnosing leakage of the fuel evaporation system. The method is used for the leakage diagnosis process of the fuel evaporation system.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of automobile electronic control, and in particular to a leakage diagnosis method for a fuel evaporation system and related equipment. BACKGROUND

[0002] In the field of automobile emission control, the leakage diagnosis of the fuel evaporation system needs to meet the mandatory requirements of the stringent regulations such as the sixth national standard, and in particular needs to accurately detect a leakage aperture of 1 mm or more to avoid fuel vapor pollution of the environment; the traditional mainstream scheme adopts a pressure decay diagnosis method, that is, the leakage degree is indirectly inferred by monitoring the pressure change rate in the system pressure maintaining stage, but this method is prone to false positives triggered by non-leakage factors, and the above false positives not only increase the after-sales maintenance cost, but also cause the user to question the reliability of the vehicle. SUMMARY

[0003] In view of the above problems, the present application provides a leakage diagnosis method for a fuel evaporation system and related equipment, and the main purpose is to solve the problem that the leakage decay diagnosis method of the traditional fuel evaporation system is prone to false positives.

[0004] To solve the above at least one technical problem, in a first aspect, the present application provides a leakage diagnosis method for a fuel evaporation system, which comprises:

[0005] obtaining a basic parameter of the fuel evaporation system in a vacuum pumping stage, wherein the fuel evaporation system meets the sealing and desorption capacity standards of the carbon canister electromagnetic valve, and the basic parameter includes an initial pressure, an end pressure, a pressure change curve and a liquid level correction coefficient;

[0006] calculating a gas loss mass based on the basic parameter;

[0007] calculating a leakage aperture based on the gas loss mass and the basic parameter, wherein the leakage aperture is used to diagnose the leakage of the fuel evaporation system.

[0008] Optionally, before the step of obtaining the basic parameter of the fuel evaporation system in the vacuum pumping stage, it comprises:

[0009] detecting the lateral acceleration and the longitudinal acceleration of the vehicle;

[0010] in the case that the lateral acceleration and / or the longitudinal acceleration is less than a preset acceleration, obtaining a current leakage diagnosis condition of the vehicle;

[0011] in the case that the vehicle meets the leakage diagnosis condition, closing the carbon canister electromagnetic valve and the carbon canister ventilation valve of the fuel evaporation system to perform a gas pumping operation;

[0012] detecting the pressure drop rate of the fuel tank under the gas pumping operation;

[0013] determining that the carbon canister electromagnetic valve is leaking when the pressure drop rate is greater than a preset threshold value;

[0014] determining that the carbon canister electromagnetic valve is sealed when the pressure drop rate is less than or equal to the preset threshold value.

[0015] Optionally, before the step of obtaining the basic parameter of the fuel evaporation system in the vacuumizing stage, the method comprises:

[0016] performing a gas extraction operation when the carbon canister breather valve is closed and the carbon canister electromagnetic valve is opened at a preset opening degree;

[0017] detecting a pressure value of the fuel tank under the gas extraction operation;

[0018] determining that the desorption capacity of the fuel evaporation system is substandard when the pressure value does not drop to a target pressure value within a preset time;

[0019] determining that the desorption capacity of the fuel evaporation system is up to standard when the pressure value drops to the target pressure value within the preset time.

[0020] Optionally, the initial pressure is determined based on the target pressure value, and the calculation of the gas loss mass based on the basic parameter comprises:

[0021] determining a fuel tank effective volume based on a liquid level correction coefficient and a fuel tank calibration volume, wherein the fuel tank effective volume is used to represent a volume actually participating in the change of the gas loss under the influence of the lower liquid level in the fuel tank;

[0022] calculating the gas loss mass based on the following formula:

[0023]

[0024] wherein P B is the end pressure, P0 is the initial pressure, V1 is the fuel tank effective volume, K is the gas constant, and T is the temperature.

[0025] Optionally, the calculation of the leakage hole diameter based on the gas loss mass and the basic parameter comprises:

[0026] determining an integral value based on the pressure change curve and the gas density, wherein the integral value represents the cumulative effect of the gas flow in the pressure maintaining stage after the vacuumizing stage;

[0027] calculating a leakage hole area based on the following formula:

[0028]

[0029] wherein Δ m is the gas loss mass, and Cq is a flow coefficient, I is an integral value;

[0030] determining the leak hole diameter based on the leak hole area.

[0031] Optionally, the integral value is determined based on the pressure change curve and the gas density, comprising:

[0032] determining a pressure value at each time point based on the pressure change curve, wherein the pressure value is taken as an absolute value;

[0033] determining a transient flow related quantity based on the pressure value at each time point and the gas density;

[0034] discretizing a time range of the pressure change curve into at least two time intervals;

[0035] applying a trapezoidal rule based on the transient flow related quantity and the time interval to determine the integral value.

[0036] Optionally, the above method further comprises:

[0037] in a case where the leak hole diameter is less than a preset hole diameter, keeping the carbon can electromagnetic valve closed and opening the carbon can vent valve to perform an air intake operation;

[0038] detecting a pressure value of the oil tank under the air intake operation;

[0039] in a case where the pressure value rises to an atmospheric pressure value within a preset time, determining that the carbon can vent valve is not stuck;

[0040] in a case where the pressure value does not rise to the atmospheric pressure value within the preset time, determining that the carbon can vent valve is stuck.

[0041] In a second aspect, an embodiment of the present application further provides a leak diagnosis device of a fuel evaporation system, comprising:

[0042] an acquisition unit configured to acquire basic parameters of the fuel evaporation system in a vacuum pumping stage, wherein the fuel evaporation system meets carbon can electromagnetic valve sealing and desorption capacity standards, and the basic parameters include an initial pressure, an ending pressure, a pressure change curve, and a liquid level correction coefficient;

[0043] a first calculation unit configured to calculate a gas loss mass based on the basic parameters;

[0044] a second calculation unit configured to calculate a leak hole diameter based on the gas loss mass and the basic parameters, wherein the leak hole diameter is used to diagnose a leak of the fuel evaporation system.

[0045] In order to achieve the above object, according to a third aspect of the present application, there is provided a computer readable storage medium comprising a stored program, wherein the steps of the above-mentioned method for diagnosing a leak of a fuel vaporization system are implemented when the above-mentioned program is executed by a processor.

[0046] In order to achieve the above object, according to a fourth aspect of the present application, there is provided an electronic device comprising at least one processor and at least one memory connected to the processor; wherein the processor is configured to invoke program instructions in the memory to implement the steps of the above-mentioned method for diagnosing a leak of a fuel vaporization system.

[0047] By means of the above technical solution, the method for diagnosing a leak of a fuel vaporization system and related device provided by the present application can solve the problem that the conventional leak attenuation diagnosis method of the fuel vaporization system is prone to false positives. The method comprises the following steps: obtaining basic parameters of the fuel vaporization system in a vacuum extraction stage, wherein the fuel vaporization system meets the requirements of a carbon canister electromagnetic valve sealing and a desorption capacity, and the basic parameters include an initial pressure, an ending pressure, a pressure change curve and a liquid level correction coefficient; calculating a gas loss mass based on the basic parameters; and calculating a leak aperture based on the gas loss mass and the basic parameters, wherein the leak aperture is used to diagnose a leak of the fuel vaporization system. In the above solution, the system pressure change is converted into a physical mass loss, and then the leak physical size is inversely deduced by means of a gas flow equation. The basic parameters in the vacuum extraction stage are obtained on the premise that the system state is reliable, i.e., the carbon canister electromagnetic valve sealing excludes external interference, and the desorption capacity meets the requirement of system integrity. The gas loss mass is calculated based on the pressure difference by means of a deformation of the ideal gas state equation, so as to convert the pressure change into an accurate physical mass loss, thereby reducing the limitation of the conventional method which depends on the pressure change rate. Finally, the leak aperture is inversely deduced by means of the mass conservation principle according to the mass flow equation. This way of directly deducing the leak physical size from the mass loss reduces the misjudgment probability caused by the system volume change, temperature drift or transient disturbance in the conventional method.

[0048] Correspondingly, the fuel vaporization system leak diagnosis device, the electronic device and the computer readable storage medium provided by the embodiments of the present application also have the above technical effects.

[0049] The above description is only a summary of the technical solutions of the present application. In order to enable one skilled in the art to better understand the technical means of the present application, the specific embodiments of the present application can be implemented according to the content of the description, and in order to make the above and other objects, characteristics and advantages of the present application more obvious and easy to understand, the following specific embodiments of the present application are described. BRIEF DESCRIPTION OF DRAWINGS

[0050] Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments with reference made to the accompanying drawings. The drawings are for purposes of illustration only and are not intended to limit the present application thereto, as the present application can have application in forms other than those illustrated. Moreover, each of the figures can not be to scale as is commonly practiced in the art in order to illustrate features which are relative. In the Figures:

[0051] Figure 1 A flow chart of a method for diagnosing a leak in a fuel vapor system is shown;

[0052] Figure 2 A block diagram of a leak diagnosis device for a fuel vapor system is shown;

[0053] Figure 3 A block diagram of a leak diagnosis electronic device for a fuel vapor system is shown. DETAILED DESCRIPTION

[0054] Exemplary embodiments of the present application will be described herein below with reference to the accompanying drawings. Although exemplary embodiments of the present application are shown in the drawings, it should be understood that the present application can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided so that this application will be thorough and complete, and will fully convey the scope of the application to those skilled in the art.

[0055] To solve the problem that the conventional leak decay diagnosis method for a fuel vapor system is prone to false positives, an embodiment of the present application provides a method for diagnosing a leak in a fuel vapor system, as shown in Figure 1 The method comprises:

[0056] S101, obtaining a base parameter of the fuel vapor system in a vacuum stage, wherein the fuel vapor system meets a carbon canister electromagnetic valve sealing and a desorption capacity standard, and the base parameter comprises an initial pressure, an end pressure, a pressure change curve, and a liquid level correction coefficient;

[0057] This step first ensures that the system is free from external gas interference through the carbon canister electromagnetic valve sealing state, that is, the valve tightness has been verified, and air abnormal infiltration leading to pressure data distortion is excluded. At the same time, the desorption capacity standard confirms that the system vacuum function is normal, ensuring that the subsequent pressure change is caused only by the leak, and avoiding the failure of negative pressure establishment due to insufficient pump suction capacity.

[0058] In this environment, the basic parameters are collected: the initial pressure represents the absolute negative pressure value of the system at the beginning of the pressure maintaining stage, serving as the reference point for mass change calculation; the end pressure represents the negative pressure value of the system at the end of the pressure maintaining stage, and the difference between the initial pressure and the end pressure is directly related to the gas loss; the pressure change curve records the pressure fluctuation throughout the period from the initial to the end, capturing the nonlinear characteristics of the leakage rate through the time dimension, such as the slow pressure rise of a small leak or the rapid balancing effect of a large leak; the liquid level correction coefficient is dynamically adjusted based on the actual fuel volume proportion of the tank, and the higher the liquid level, the smaller the compressible space for gas, which is used to compensate for the influence of liquid occupying volume on the sensitivity of gas pressure.

[0059] The above parameters collectively form the basis for the application of the law of conservation of mass: the initial / end pressure provides the state boundary, the pressure change curve depicts the dynamic process, and the liquid level coefficient corrects the system volume variable. Finally, the pressure change is converted into a calculable mass loss through the gas state equation, thereby reducing the one-sidedness of traditional methods that rely solely on the pressure rate at a certain moment.

[0060] In one embodiment, the step of obtaining the basic parameters of the fuel evaporation system during the vacuum pumping stage comprises:

[0061] detecting the lateral acceleration and the longitudinal acceleration of the vehicle;

[0062] if the lateral acceleration and / or the longitudinal acceleration is less than a preset acceleration, obtaining the current leakage diagnosis condition of the vehicle;

[0063] if the vehicle meets the leakage diagnosis condition, closing the carbon canister electromagnetic valve and the carbon canister ventilation valve of the fuel evaporation system to perform a gas pumping operation;

[0064] detecting the pressure drop rate of the tank under the gas pumping operation;

[0065] if the pressure drop rate is greater than a preset threshold, determining that the carbon canister electromagnetic valve is leaking;

[0066] if the pressure drop rate is less than or equal to the preset threshold, determining that the carbon canister electromagnetic valve is sealed.

[0067] For example, the lateral acceleration refers to the acceleration in the left-right direction of the vehicle, reflecting the degree of roll when turning; the longitudinal acceleration refers to the acceleration in the front-rear direction of the vehicle, reflecting the degree of pitch when rapid acceleration / braking; the preset acceleration refers to a threshold value for determining the violent shaking of the vehicle (lateral > 0.6g / longitudinal > 0.5g); the leakage diagnosis condition refers to the vehicle meeting the preset working condition environment requirements, such as the environmental temperature range, the upper limit of the oil tank level, the sensor fault-free, etc., to ensure that the system is in a stable test state; the carbon can electromagnetic valve is a switch valve for controlling the fuel vapor from the carbon can into the engine intake manifold, and its airtightness directly affects the air tightness of the system; the carbon can ventilation valve is a valve for connecting the carbon can and the atmosphere, which can isolate external air interference after being closed; the air extraction operation refers to extracting the gas in the system through the engine intake manifold vacuum or external equipment, so as to form a negative pressure environment in the oil tank; the pressure drop rate represents the increase speed of the negative pressure of the oil tank per unit time, reflecting the efficiency of the extracted gas; and the preset threshold value is a critical value calibrated according to the system volume, air extraction power, etc., for judging whether the gas loss is abnormal.

[0068] This step first tracks the lateral acceleration (the roll force in the Y-axis direction of the vehicle when turning, reflecting the violent degree of left-right shaking of the liquid in the fuel tank) and the longitudinal acceleration (the pitch force in the X-axis direction when rapid acceleration / braking, reflecting the violent degree of front-rear surge of the fuel), and when both are strictly lower than the preset threshold value (i.e., the vehicle body is dynamically stable), the leakage diagnosis condition (basic working condition verification such as water temperature, vehicle speed, etc.) is allowed to enter. Further, by using the characteristics of the leakage hole as a gas escape channel, the physical sealing state of the carbon can electromagnetic valve is inferred through the pressure dynamic response under the air extraction operation. When the double valves are closed to form a closed system, the air extraction operation is started to extract the gas: if the carbon can electromagnetic valve has a physical leakage, the leakage hole will become an additional gas escape channel, causing the gas in the system to flow out through the hole to the engine negative pressure end, resulting in a rapid pressure drop and a rapid increase in negative pressure. At this time, the pressure drop rate is greater than the preset threshold value, and the valve leakage is determined accordingly. On the contrary, if the carbon can electromagnetic valve is completely airtight, the gas can only be slowly extracted through the designed path (such as the carbon can pipeline), the pressure drops gently, the rate is less than or equal to the preset threshold value, or even cannot be extracted, the rate tends to zero, and the valve is determined to be airtight accordingly.

[0069] The above scheme ensures vehicle body stability. If the acceleration exceeds the standard (e.g., lateral acceleration > 0.6g during sharp turning), the fuel will shake violently, which will flood the fuel tank pressure sensor (when the sensor is covered with liquid, the reading will be distorted due to the incompressibility of fuel). When the acceleration is controlled, the pressure sensor can accurately capture the gas dynamics. If the pressure drop rate > the preset threshold (reflecting the speed of negative pressure increase per unit time), the only cause of the physical leakage of the carbon canister electromagnetic valve (leakage hole forms a gas escape channel, causing the system gas to accelerate and flow to the engine negative pressure end, resulting in abnormal negative pressure increase) establishes a systematic defense strategy at the diagnosis entrance, reducing the risk of false positives caused by sensor distortion and valve failure. The special phenomenon of capturing the leakage hole accelerating gas loss transforms the traditional understanding of "leakage leading to pressure recovery" into a detectable signal. From the perspective of fluid dynamics, a valve state verification model is constructed, which eliminates the interference factors of valve failure for subsequent leakage hole diameter calculation, thereby reducing the risk of false positives caused by component failure.

[0070] In one embodiment, the step of obtaining the basic parameters of the fuel evaporation system during the vacuum stage comprises:

[0071] In the case of closing the carbon canister vent valve and opening the carbon canister electromagnetic valve at a preset opening degree, perform the air extraction operation;

[0072] Under the air extraction operation, detect the pressure value of the fuel tank;

[0073] If the pressure value does not drop to the target pressure value within the preset time, determine that the desorption capacity of the fuel evaporation system is not up to standard;

[0074] If the pressure value drops to the target pressure value within the preset time, determine that the desorption capacity of the fuel evaporation system is up to standard.

[0075] For example, the carbon canister vent valve is closed to isolate external air interference and ensure that the system forms a closed gas circuit. The carbon canister electromagnetic valve is opened at a preset opening degree to make the valve in a fixed flow state. The opening degree value is selected through calibration to balance the air extraction efficiency and system stability. The air extraction operation uses the negative pressure generated by the engine intake manifold or an auxiliary vacuum pump to continuously extract the gas in the system through the opened carbon canister electromagnetic valve. The fuel tank pressure value is monitored by a pressure sensor in real time, reflecting the change in the total amount of gas in the system. The preset time is a reasonable time threshold value determined according to the system volume and air extraction power. The target pressure value is a negative pressure target state (e.g., -5kPa relative pressure) set according to regulations or experimental data, representing the vacuum level that the system should reach.

[0076] The step simulates the vacuum condition by controlling the valve state, monitors whether the system pressure change meets the expected dynamic response, and thus judges the fuel evaporation system's desorption capacity. When the carbon canister vent valve is closed and the carbon canister electromagnetic valve is opened at a fixed opening, the system forms a one-way gas escape path: the engine negative pressure continuously sucks gas through the electromagnetic valve channel, and in the ideal state, the pressure should decrease steadily over time. If the system's desorption capacity meets the standard, there is no blockage in the pipeline, no jamming of the electromagnetic valve, and no accidental leakage, the gas is efficiently extracted, and the pressure value will continuously decrease to the target pressure value within the preset time; otherwise, if there are functional defects such as carbon canister blockage, insufficient actual opening of the electromagnetic valve, or pipeline leakage, the gas extraction efficiency is low, and the pressure value cannot decrease to the target value within the preset time.

[0077] Through the above scheme, the actual vacuum performance of the system is quantified from the perspective of gas dynamics through double judgment of time constraints and pressure targets, the abstract "desorption capacity" is converted into measurable pressure-time response characteristics, and the subsequent leak hole diameter calculation in the pressure maintaining stage can be performed on the normally functioning system, thereby reducing the risk of diagnostic distortion caused by functional degradation of the system.

[0078] S102, calculating a gas loss mass based on the basic parameters;

[0079] In one embodiment, the initial pressure is determined based on the target pressure value, and the calculating a gas loss mass based on the basic parameters comprises:

[0080] determining an effective volume of the oil tank based on a liquid level correction coefficient and a tank calibration volume, wherein the effective volume of the oil tank is used to represent the volume actually participating in the change of gas loss in the oil tank under the liquid level;

[0081] calculating the gas loss mass based on the following formula:

[0082]

[0083] wherein P B is the end pressure, P0 is the initial pressure, V1 is the effective volume of the oil tank, K is the gas constant, and T is the temperature.

[0084] The initial pressure is an initial relative pressure value of the system at the beginning of the pressure maintaining phase, i.e., the target pressure value in the negative pressure state, representing the initial gas state reference; the end pressure is a relative pressure value of the system at the end of the pressure maintaining phase, reflecting the state after gas loss; the liquid level correction coefficient is obtained based on a real-time tank liquid level percentage table, and the higher the liquid level, the smaller the coefficient, which is used to correct the influence of the liquid occupying space on the gas volume; the tank calibration volume is the inherent volume of the fuel evaporation system hardware, including the tank, pipeline, etc.; the tank effective volume is the actual gas compressible space calculated from the liquid level correction coefficient and the calibration volume; the gas constant is a physical constant related to pressure, volume and temperature in the ideal gas state equation; and the temperature is a gas Kelvin temperature value, which is obtained in real time by a vehicle sensor and reflects the thermodynamic state of the gas.

[0085] The liquid level correction coefficient reference table is as follows:

[0086] 10％ 20％ 30％ 40％ 50％ 60％ 70％ 80％ 90％ 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1

[0087] This step uses the ideal gas state equation to establish a quantitative relationship between pressure-volume-temperature and gas mass, and compensates for the influence of the actual space change of the tank on the calculation result through liquid level correction.

[0088] First, the tank effective volume is dynamically adjusted by the liquid level correction coefficient. For example, when the liquid level is high, the fuel occupies more space, and the gas compressible volume decreases, thereby accurately representing the physical space actually participating in the change of gas loss.

[0089] Then, based on the principle of the ideal gas state equation: the system pressure change is proportional to the gas mass change, and inversely proportional to the effective volume and temperature. Specifically, the total amount of gas decreases due to leakage during the pressure maintaining phase, resulting in a change in pressure value from the initial pressure to the end pressure, and a decrease in the absolute value of the negative pressure. The product of this pressure difference and the effective volume (pressure change x space scale) divided by the product of temperature and the gas constant (temperature affects gas density) can calculate the mass of the lost gas.

[0090] Through the above scheme, the error is reduced in the following three aspects: 1. The liquid level correction solves the gas space difference caused by different fuel amounts; 2. The temperature compensation excludes the thermal expansion and contraction effect of the gas; and 3. The pressure difference is used instead of the traditional pressure rate to directly relate to the mass loss, thereby constructing a more essential leakage quantification basis.

[0091] S103, calculating a leakage aperture based on the gas loss mass and the basic parameters, wherein the leakage aperture is used to diagnose the leakage of the fuel evaporation system.

[0092] In one embodiment, the calculating a leakage aperture based on the gas loss mass and the basic parameters comprises:

[0093] determining an integral value based on the pressure change curve and gas density, wherein the integral value represents a cumulative effect of gas flow during the pressure maintaining phase after the vacuumizing phase;

[0094] calculating the leakage hole area based on the following formula:

[0095]

[0096] wherein Δ m is the gas loss mass, C q is the flow coefficient, and I is the integral value;

[0097] determining the leakage hole diameter based on the leakage hole area.

[0098] For example, the gas loss mass is the total mass of the gas lost by the system during the pressure maintaining phase, which is calculated based on the pressure difference, effective volume, and temperature in the previous step; the flow coefficient is a dimensionless parameter representing energy loss of the fluid passing through the hole, which is determined by the geometric characteristics of the hole; the pressure change curve is the time series data recorded by the pressure sensor during the pressure maintaining phase, reflecting the dynamic process of gas loss caused by leakage; the gas density is the mass per unit volume of the gas, which changes with temperature and pressure; the integral value is a scalar value calculated by time integration of the pressure change curve and the gas density, representing the cumulative effect of the gas flow through the leakage hole during the pressure maintaining phase.

[0099] This step uses integral operation to capture the time cumulative effect of gas flow, and reverses the leakage hole area in combination with the fluid dynamics characteristics.

[0100] First, the integral value I is calculated using the pressure change curve and the gas density: by integrating the pressure value (taking the absolute value) at each time point in combination with the gas density, the discrete pressure fluctuations are converted into continuous gas flow accumulation, which fully considers the influence of nonlinear pressure change on flow rate during the leakage process. The pressure difference drives the gas flow, and the flow rate is proportional to the square root of the pressure difference.

[0101] Subsequently, based on the principle of mass flow equation of thin-walled small hole: the total mass of the gas passing through the leakage hole is equal to the product of the flow coefficient, the leakage hole area, and the integral value. Accordingly, the gas loss mass, i.e., the actual loss amount of the system, is equivalent to the mass flow through the hole, and the leakage hole area is reversely deduced.

[0102] Through the above scheme, the error is reduced by double coupling: 1. The integral value captures the pressure dynamic process, solving the one-sidedness of the traditional method of taking a single point pressure value; 2. The flow coefficient compensates for the influence of the hole shape on the flow, finally converting the area into a physical hole diameter, and constructing a direct physical mapping of the leakage size.

[0103] In one embodiment, the determining of the integral value based on the pressure change curve and the gas density comprises:

[0104] determining a pressure value at each time point based on the pressure change curve, wherein the pressure value is taken as an absolute value;

[0105] determining a transient flow-related quantity based on the pressure value at each time point and the gas density;

[0106] discretizing a time range of the pressure change curve into at least two time intervals;

[0107] applying a trapezoidal rule based on the transient flow-related quantity and the time intervals to determine the integral value.

[0108] Exemplarily, the pressure change curve is a time series data stream recorded by a pressure sensor during a pressure maintaining stage, which fully reflects a continuous trajectory of system pressure fluctuation over time; the pressure value is a system relative pressure measurement value (negative pressure state) corresponding to each sampling point in the curve; the absolute value operation converts the negative pressure value into a positive pressure difference amplitude, eliminating the sign interference to directly represent the actual driving pressure difference on both sides of the leakage hole; the gas density is the mass per unit volume of the gas, which depends on the real-time temperature and pressure state, and is used to convert the pressure difference into a flow-related quantity; the transient flow-related quantity is a transient physical quantity calculated based on the absolute value of the pressure difference and the gas density, which is proportional to the square root of the pressure difference, and reflects the potential flow rate tendency of the gas passing through the leakage hole at this time point; the time range is the total duration of the pressure maintaining stage; the time interval is a discrete small section (such as every 0.1 second interval) divided from the continuous time range, realizing the discretization processing of the continuous signal; the trapezoidal rule is a numerical integration technique, which calculates the area of each trapezoid by regarding the transient flow-related quantity of adjacent time points as the top side of the trapezoid and the time interval as the bottom side, and then accumulates the areas to approximate the total area under the curve; the integral value is the final output scalar, representing the cumulative scale of the gas flow through the leakage hole during the entire pressure maintaining process.

[0109] This step converts the continuous pressure dynamic change into a discrete time-flow correlation sequence, and then approximates the real integral value through trapezoidal area accumulation, thereby quantifying the total effect of gas loss during the leakage process.

[0110] First, the pressure values of dense sampling points are extracted from the pressure change curve, such as 100 points per second, and the actual pressure difference driving quantity is obtained after taking the absolute value to eliminate the negative sign; the transient flow-related quantity at each time point is calculated by combining the gas density (compensated by temperature), which directly reflects the instantaneous contribution of the pressure difference to the flow rate; then the total time range is cut into equal-length small intervals (discretization processing), and for each interval, the transient flow-related quantities at the beginning and end are taken, and their average value is multiplied by the time interval length to obtain the approximate trapezoidal area value of that time period; finally, the trapezoidal areas of all time intervals are accumulated to form a geometric approximation of the total area under the pressure change curve.

[0111] By the above scheme, the error is reduced through triple optimization: 1. Dense sampling captures the details of the nonlinear fluctuations of pressure; 2. Discretization converts the continuous problem into a computable discrete sequence; 3. The trapezoidal rule uses linear interpolation to replace complex function integration, which significantly reduces the computational complexity while ensuring accuracy, providing high-fidelity flow accumulation input for the calculation of the leakage hole area.

[0112] In an embodiment, the above method further comprises:

[0113] In the case where the leakage hole diameter is less than the preset hole diameter, the carbon canister electromagnetic valve is kept closed, and the carbon canister vent valve is opened to perform the air intake operation;

[0114] Under the air intake operation, the pressure value of the oil tank is detected;

[0115] In the case where the pressure value rises to the atmospheric pressure value within a preset time, it is determined that the carbon canister vent valve is not stuck;

[0116] In the case where the pressure value does not rise to the atmospheric pressure value within a preset time, it is determined that the carbon canister vent valve is stuck.

[0117] For example, the leakage hole diameter less than the preset hole diameter means that the system has been confirmed to have no significant leakage (e.g., hole diameter ≤ 1 mm) by the previous step, excluding the interference of leakage on pressure change; the carbon canister electromagnetic valve is kept closed to cut off the connection with the engine, preventing accidental gas escape; the carbon canister vent valve is opened for air intake operation, making the valve in a to-be-verified state, which should theoretically allow external air to enter the system; the oil tank pressure value is monitored by a sensor in real time, reflecting the change in the total amount of gas inside the system; the preset time is a reasonable recovery time based on the system volume and atmospheric pressure calibration; the atmospheric pressure value is the environmental air pressure level, serving as the target benchmark for pressure recovery; no sticking means that the valve can be normally opened to guide the air flow; sticking means that the valve cannot be opened or opened insufficiently due to mechanical failure (e.g., carbon deposition, deformation).

[0118] The step utilizes the gas inflow process under negative pressure environment to judge whether the valve is normally opened by monitoring the speed of pressure recovery to atmospheric pressure. When the system is confirmed to have no leakage and is in a negative pressure state through the previous step, the carbon can vent valve is actively opened: if the valve function is normal, external air (atmospheric pressure) flows freely into the system through the vent valve, the gas inflows to compensate the negative pressure space, causing the pressure value to quickly rise to atmospheric pressure level, the recovery rate matches the valve opening degree and the system volume, and the standard can be reached within the preset time; otherwise, if the valve has a jam fault, such as valve core adhesion or foreign matter obstruction, the air inflow path is blocked or interrupted, and the gas cannot effectively enter the system, the pressure recovery is significantly delayed, and the atmospheric pressure value cannot be reached within the preset time. This verification mechanism creatively uses the negative pressure recovery rate as an indirect representation of the valve action ability. When normally opened, air flows freely to form a rapid pressure balance, and when jammed, gas compensation is blocked, causing recovery delay, thereby constructing a valve functionality diagnostic model without adding new sensors.

[0119] Through the above scheme, the confusion between "leakage fault" and "valve jam" in traditional diagnosis is solved through time constraint and target pressure double judgment: the pressure recovery test is performed under the premise of no leakage to ensure independent identification of valve failure, thereby reducing the risk of false positives caused by valve mechanical failure.

[0120] Considering that the traditional scheme directly monitors the pressure recovery rate (absolute value of negative pressure decreases) during the pressure maintaining stage, and determines leakage if it exceeds the threshold. It is easily disturbed by temperature drift (gas thermal expansion and contraction), volume change (fuel level fluctuation) and transient disturbance (sensor noise). However, the present scheme takes the pressure curve as an intermediate input, first converts the pressure difference into the effective volume compensated by temperature and corrected by liquid level through the gas state equation, and then calculates the gas loss mass. When the temperature rises, the mass calculation automatically compensates for the natural change of pressure, and the liquid level coefficient corrects the volume influence. Then, through time integration, the pressure fluctuation is converted into flow accumulation, the integral operation smooths the transient disturbance, and the gas density compensates for the temperature effect simultaneously. Finally, based on the thin-walled small hole fluid equation, the gas loss mass and flow accumulation are related to the physical aperture, which is inversely deduced. This chain conversion from pressure to mass to physical size makes temperature, volume and other common mode disturbances naturally cancelled out in the conversion process (such as temperature affecting mass and flow calculation simultaneously, and the ratio remains stable), and the leakage essential characteristic (aperture size) is accurately extracted, thereby preserving the value of pressure data while avoiding its defects as a direct criterion.

[0121] In summary, the system state verification and physical parameter calculation are coupled in the present application: first, through the carbon canister electromagnetic valve sealing detection, the characteristics of the accelerated gas escape leading to the abnormal increase of the pressure drop rate of the leakage hole under the gas extraction operation are used to ensure that there is no external interference, and then the desorption capacity verification is performed based on the vacuum extraction efficiency monitoring of the fixed opening electromagnetic valve to confirm the system functional integrity; in this reliable state, the basic parameters (including initial pressure, end pressure, continuous pressure change curve) and liquid level correction coefficient in the vacuum extraction stage are obtained, the ideal gas state equation is used to convert the correlation between pressure difference and system volume and temperature into accurate gas loss mass (the liquid level correction coefficient compensates the influence of fuel volume change on gas space in real time), and then based on the thin-walled small hole fluid dynamics principle, the gas flow accumulation effect of the leakage process is captured through the time integration of the pressure change curve, and the gas loss mass is inversely calculated into the leakage hole area and converted into the physical aperture. This double physical model mapping from mass conservation (gas loss) to flow conservation (leakage hole mass flow) reduces the limitations of the traditional method which simply relies on the pressure change rate. The pressure change rate is easy to be disturbed by temperature drift, instantaneous disturbance or volume change, but the present application directly quantifies the leakage physical size to establish the essential characterization of the leakage state, thereby reducing the misjudgment probability caused by environmental fluctuations, system volume differences or accidental factors.

[0122] Further, as an implementation of the method shown in the above Figure 1 , the embodiment of the present application also provides a fuel evaporation system leakage diagnosis device for implementing the method shown in the above Figure 1 . The device embodiment corresponds to the foregoing method embodiment, and for the convenience of reading, the details in the foregoing method embodiment will not be described one by one, but it should be clear that the device in the present embodiment can correspondingly implement all the contents in the foregoing method embodiment. As shown in the above Figure 2 , the device comprises an acquisition unit 21, a first calculation unit 22 and a second calculation unit 23, wherein,

[0123] The acquisition unit 21 is configured to acquire the basic parameters of the fuel evaporation system in the vacuum extraction stage, wherein the fuel evaporation system meets the carbon canister electromagnetic valve sealing and the desorption capacity standard, and the basic parameters include the initial pressure, the end pressure, the pressure change curve and the liquid level correction coefficient;

[0124] The first calculation unit 22 is configured to calculate the gas loss mass based on the basic parameters;

[0125] The second calculation unit 23 is configured to calculate the leakage aperture based on the gas loss mass and the basic parameters, wherein the leakage aperture is used for diagnosing the leakage of the fuel evaporation system.

[0126] The processor comprises a core, and the core retrieves corresponding program units in the memory.

[0127] The embodiment of the present application provides a computer readable storage medium, which comprises a stored program, and the program is executed by a processor to implement the leakage diagnosis method of the fuel evaporation system.

[0128] The embodiment of the present application provides a processor, which is used for running a program, wherein the program is executed to implement the leakage diagnosis method of the fuel evaporation system.

[0129] The embodiment of the present application provides an electronic device, which comprises at least one processor and at least one memory connected with the processor, and the processor is used for calling program instructions in the memory to execute the leakage diagnosis method of the fuel evaporation system.

[0130] The embodiment of the present application provides an electronic device 30, as shown in the figure, the electronic device comprises at least one processor 301 and at least one memory 302 connected with the processor, and a bus 303, wherein the processor 301 and the memory 302 complete mutual communication through the bus 303, and the processor 301 is used for calling program instructions in the memory to execute the leakage diagnosis method of the fuel evaporation system. Figure 3

[0131] The intelligent electronic device in the present application can be a PC, a PAD, a mobile phone or the like.

[0132] The present application further provides a computer program product, which is suitable for executing a program of the leakage diagnosis method of the fuel evaporation system when the program is executed on the process management electronic device.

[0133] It should be noted that in the above embodiments, the description of each embodiment has its own emphasis, and the parts not described in detail in an embodiment can be referred to the related description of other embodiments.

[0134] Those skilled in the art should understand that the embodiments of the present application can be provided as a method, a system or a computer program product. Therefore, the present application can be in the form of a complete hardware embodiment, a complete software embodiment or an embodiment combining software and hardware aspects. Moreover, the present application can be in the form of a computer program product implemented on one or more computer usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer usable program codes. ​

[0135] The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks. Figure 1 one or more flow or blocks Figure 1 means for functionally implementing the steps in flowchart block or blocks.

[0136] These computer program instructions can also be stored in a computer readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer readable memory produce an article of manufacture including instructions which implement the function specified in the flowchart block or blocks. Figure 1 one or more flow or blocks Figure 1 means for functionally implementing the steps in flowchart block or blocks.

[0137] The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks. Figure 1 one or more flow or blocks Figure 1 means for functionally implementing the steps in flowchart block or blocks.

[0138] The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks. Figure 1 flow corresponding to the control of the memory in the embodiments.

[0139] The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on the computer, the processes or functions according to the embodiments of the present application are generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another computer-readable storage medium, for example, the computer instructions can be transmitted from one website, computer, server or data center to another website, computer, server or data center through wired (such as coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (such as infrared, wireless, microwave, etc.) mode. The computer-readable storage medium can be any available medium that the computer can store or be integrated into a data storage device such as a server, data center, etc. containing one or more available media. The available media can be a magnetic medium (for example, a floppy disk, a hard disk, a magnetic tape), an optical medium (for example, a DVD), or a semiconductor medium (for example, a solid state disk (SSD)), etc.

[0140] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working process of the above-described system, device and unit can refer to the corresponding process in the foregoing method embodiments, which will not be repeated here.

[0141] In several embodiments provided in the present application, it should be understood that the disclosed system, device and method can be implemented in other ways. For example, the device embodiments described above are only schematic, for example, the division of units is only a logical function division, and actual implementation can have another division manner, for example, a plurality of units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the coupling or direct coupling or communication connection between the units or components shown or discussed can be indirect coupling or communication connection through some interfaces, devices or units, and can be electrical, mechanical or other forms.

[0142] The units described as separate components can or can not be physically separated, and the components shown as units can or can not be physical units, that is, they can be located in one place, or they can be distributed on a plurality of network units. Part or all of the units can be selected according to actual needs to achieve the purpose of the embodiments.

[0143] In addition, each of the functional units in the various embodiments of the present application can be integrated in one processing unit, or each unit can be physically present separately, or two or more units can be integrated in one unit. The integrated unit can be realized in the form of hardware or in the form of a software functional unit.

[0144] When the integrated unit is realized in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer readable storage medium. Based on such understanding, the technical solutions of the present application, essentially or in part, or all or part of the technical solutions can be embodied in the form of a software product. The computer software product is stored in a storage medium, and includes several instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the various embodiments of the method of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM), random access memory (RAM), magnetic disk or optical disk, and various other media that can store program codes.

[0145] The above, the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present application.

Claims

1. A method of diagnosing a leak in a fuel vapor system, comprising: The method comprises: acquiring basic parameters of the fuel evaporation system during a vacuum stage, wherein the fuel evaporation system meets the standards of canister electromagnetic valve sealing and desorption capacity, and the basic parameters include initial pressure, end pressure, pressure change curve and liquid level correction coefficient; calculating gas loss mass based on the basic parameters; calculating a leak hole diameter based on the gas loss mass and the basic parameters, wherein the leak hole diameter is used to diagnose the leak of the fuel evaporation system.

2. The method of claim 1, wherein, Before the step of acquiring the basic parameters of the fuel evaporation system during the vacuum stage, the method comprises: detecting lateral acceleration and longitudinal acceleration of the vehicle; acquiring current leak diagnosis conditions of the vehicle when the lateral acceleration and / or the longitudinal acceleration is less than a preset acceleration; closing a canister electromagnetic valve and a canister breather valve of the fuel evaporation system to perform a gas extraction operation when the vehicle meets the leak diagnosis conditions; detecting a pressure drop rate of the fuel tank under the gas extraction operation; determining that the canister electromagnetic valve leaks when the pressure drop rate is greater than a preset threshold; determining that the canister electromagnetic valve is sealed when the pressure drop rate is less than or equal to the preset threshold.

3. The method of claim 2, wherein, Before the step of acquiring the basic parameters of the fuel evaporation system during the vacuum stage, the method comprises: performing a gas extraction operation when the canister breather valve is closed and the canister electromagnetic valve is opened at a preset opening degree; detecting a pressure value of the fuel tank under the gas extraction operation; determining that the desorption capacity of the fuel evaporation system is not up to standard when the pressure value does not drop to a target pressure value within a preset time; determining that the desorption capacity of the fuel evaporation system is up to standard when the pressure value drops to the target pressure value within the preset time.

4. The method of claim 3, wherein, The initial pressure is determined based on the target pressure value, and the calculation of the gas loss mass based on the basic parameters comprises: determining an effective volume of the fuel tank based on the liquid level correction coefficient and a tank calibration volume, wherein the effective volume of the fuel tank is used to represent the volume actually participating in the change of gas loss under the influence of the lower liquid level; calculating the gas loss mass based on the following formula: where P B is the end pressure, P0 is the initial pressure, V1 is the tank effective volume, K is the gas constant, and T is the temperature.

5. The method of claim 4, wherein, The calculation of the leak hole diameter based on the gas loss mass and the basic parameters comprises: determining an integral value based on the pressure change curve and gas density, wherein the integral value represents the cumulative effect of gas flow in the pressure maintaining stage after the vacuum stage; calculating a leak hole area based on the following formula: where Δ m is the gas loss mass, C q is the flow coefficient, and I is the integral value; determining the leak hole diameter based on the leak hole area.

6. The method of claim 5, wherein, The determination of the integral value based on the pressure change curve and gas density comprises: determining a pressure value at each time point based on the pressure change curve, wherein the pressure value is taken as an absolute value; determining a transient flow related quantity based on the pressure value at each time point and the gas density; discretizing a time range of the pressure change curve into at least two time intervals; applying the trapezoidal rule based on the transient flow related quantity and the time interval to determine the integral value.

7. The method of claim 1, wherein, The method further comprises: keeping the canister electromagnetic valve closed and opening the canister breather valve to perform an air intake operation when the leak hole diameter is less than a preset hole diameter. In the air intake operation, a pressure value of the oil tank is detected; In a case where the pressure value rises to an atmospheric pressure value within a preset time, it is determined that the carbon canister vent valve is not stuck; In a case where the pressure value does not rise to the atmospheric pressure value within the preset time, it is determined that the carbon canister vent valve is stuck.

8. A leak diagnosis device for a fuel vapor system, characterized by comprising: Further comprising: an acquisition unit configured to acquire a basic parameter of a fuel evaporation system in a vacuum pumping stage, wherein the fuel evaporation system meets a carbon canister electromagnetic valve sealing and desorption capacity standard, and the basic parameter includes an initial pressure, an end pressure, a pressure change curve, and a liquid level correction coefficient; a first calculation unit configured to calculate a gas loss mass based on the basic parameter; a second calculation unit configured to calculate a leakage aperture based on the gas loss mass and the basic parameter, wherein the leakage aperture is used to diagnose a leakage of the fuel evaporation system.

9. A computer-readable storage medium, characterized in that, The computer readable storage medium includes a stored program, wherein the program, when executed by a processor, implements the steps of the fuel evaporation system leakage diagnosis method according to any one of claims 1 to 7.

10. An electronic device, comprising: The electronic device includes at least one processor and at least one memory connected to the processor; wherein the processor is configured to call program instructions in the memory, and execute the steps of the fuel evaporation system leakage diagnosis method according to any one of claims 1 to 7.

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