Methods and devices for diagnosing leaks in fuel evaporation systems

Abstract

This application provides a method and device for diagnosing leaks in a fuel evaporation system. The fuel evaporation system includes a fuel tank with a through-hole. The leak diagnosis method is applied to the controller of the leak diagnosis device, which further includes an air pump and a pressure sensor. The air pump includes a first air port and a second air port communicating with the atmosphere. The pressure sensor is used to detect the air pressure inside the fuel tank. The leak diagnosis method includes: detecting whether the leak diagnosis device is working properly; if the leak diagnosis device is working properly, controlling the second air port to communicate with the through-hole and controlling the air pump to be in working condition, so that the air pump pumps air into or draws air from the fuel tank through the through-hole; collecting the pressure value detected by the pressure sensor, and determining whether the leakage of the fuel tank exceeds the maximum permissible leakage based on the pressure value detected by the pressure sensor.

Description

Technical Field

[0001] This application relates to the field of vehicle technology, and in particular to a method and device for diagnosing leaks in a fuel evaporation system. Background Technology

[0002] With the increase in car ownership, vehicle pollution has become a major source of air pollution and a significant cause of fine particulate matter and photochemical smog pollution.

[0003] When a car's fuel evaporation system leaks, fuel vapors can enter the air and cause air pollution. Therefore, it is necessary to check whether the car's fuel evaporation system has leaks that exceed the permissible range. Summary of the Invention

[0004] According to a first aspect of the present application, a method for diagnosing leaks in a fuel evaporation system is provided. The fuel evaporation system includes a fuel tank with a through-hole; the leak diagnosis method is applied to a controller of a leak diagnosis device, the leak diagnosis device further including an air pump and a pressure sensor; the air pump includes a first air port and a second air port communicating with the atmosphere; the pressure sensor is used to detect the air pressure inside the fuel tank; the leak diagnosis method includes:

[0005] Check whether the leak diagnostic device is working properly;

[0006] If the leak diagnosis device is working normally, it controls the second air port to connect with the through hole and controls the air pump to be in working state so that the air pump can pump air to the oil tank or draw air from the oil tank through the through hole;

[0007] The pressure value detected by the pressure sensor is collected, and the leakage of the oil tank is determined based on the pressure value detected by the pressure sensor to determine whether the leakage is greater than the maximum allowable leakage.

[0008] Optionally, the step of acquiring the pressure value detected by the pressure sensor and determining whether the leakage of the oil tank exceeds the maximum permissible leakage based on the pressure value detected by the pressure sensor includes:

[0009] When the absolute value of the first pressure value collected by the pressure sensor is a first pressure threshold, the working time of the air pump after it connects with the through hole from the second air port is obtained.

[0010] If the operating time of the air pump after connecting the second air port to the through hole is less than or equal to a first time threshold, then the leakage of the oil tank is determined to be less than or equal to the maximum permissible leakage; wherein, the leakage of the oil tank is the maximum permissible leakage, and when the absolute value of the first pressure value collected by the pressure sensor is the first pressure threshold, the operating time of the air pump after connecting the second air port to the through hole is the first time threshold; or...

[0011] The process of acquiring the pressure value detected by the pressure sensor and determining whether the leakage of the oil tank exceeds the maximum permissible leakage based on the pressure value detected by the pressure sensor includes:

[0012] When the working time of the air pump after it connects with the through hole from the second air port is a first time threshold, the first pressure value detected by the pressure sensor is collected.

[0013] If the absolute value of the first pressure value is less than the first pressure threshold, then the leakage of the oil tank is determined to be greater than the maximum allowable leakage; wherein, the leakage of the oil tank is the maximum allowable leakage, and when the absolute value of the first pressure value collected by the pressure sensor is the first pressure threshold, the working time of the air pump after it connects to the through hole from the second air port is the first duration threshold.

[0014] Optionally, when the working time of the air pump after it connects to the through hole from the second air port is a first time threshold, and the absolute value of the first pressure value is less than the first pressure threshold, after determining that the leakage of the oil tank is greater than the maximum permissible leakage, the step of collecting the pressure value detected by the pressure sensor and determining whether the leakage of the oil tank is greater than the maximum permissible leakage based on the pressure value detected by the pressure sensor further includes:

[0015] The air pump is controlled to continue operating, and when the operating time of the air pump after it connects with the through hole from the second air port reaches a second time threshold, a second pressure value detected by the pressure sensor is collected; the second time threshold is greater than the first time threshold.

[0016] If the absolute value of the second pressure value is greater than or equal to the first pressure threshold, the leakage of the oil tank is determined to be low leakage; if the second duration threshold is greater than the first duration threshold, the leakage of the oil tank is determined to be high leakage.

[0017] Optionally, the leak diagnosis device further includes a one-way flow element located between the second air port and the through hole, the flow direction of the one-way flow element being the same as the flow direction of the airflow in the air pump; the step of acquiring the pressure value detected by the pressure sensor and determining whether the leakage of the oil tank exceeds the maximum permissible leakage based on the pressure value includes:

[0018] When the working time of the air pump after it connects with the through hole from the second air port is a third time threshold, the third pressure value detected by the pressure sensor is collected.

[0019] If the absolute value of the third pressure value is greater than the second pressure threshold, the air pump is controlled to stop working, and the rate of change of the pressure value collected by the pressure sensor over time is obtained. Based on the rate of change, it is determined whether the leakage of the oil tank is greater than the maximum allowable leakage.

[0020] Optionally, obtaining the rate of change of the pressure value collected by the pressure sensor over time includes:

[0021] Obtain the pressure value collected by the pressure sensor over time, and determine the rate of change based on the curve.

[0022] Optionally, detecting whether the leak diagnostic device is working properly includes:

[0023] Control the operation of the air pump, detect the current of the air pump, and if the current of the air pump increases, it is determined that the air pump is working normally;

[0024] The air pump is controlled to continue working, and the pressure value detected by the pressure sensor is collected. If the absolute value of the collected pressure value increases, it is determined that the pressure sensor is working normally.

[0025] Optionally, the leak diagnosis device further includes a reversing control valve, which is disposed between the second air port and the through hole; the reversing control valve includes a first channel port, a second channel port, and a third channel port, wherein the first channel port communicates with the through hole, the second channel port communicates with the second air port, and the third channel port communicates with the atmosphere; the reversing control valve has a first state and a second state, wherein in the first state, the first channel port and the third channel port are connected, and in the second state, the first channel port and the second channel port are connected; the step of detecting whether the leak diagnosis device is working properly includes:

[0026] Control the reversing control valve to the first state and determine whether the air pump is working properly;

[0027] If it is determined that the air pump is working normally, control the reversing control valve to switch to the second state, and control the air pump to work, and collect the fourth pressure value detected by the pressure sensor;

[0028] If the absolute value of the fourth pressure value continues to increase, it is determined that the reversing control valve and the pressure sensor are working normally.

[0029] Optionally, the leak diagnosis device further includes a reference channel, one end of which is connected to the through hole and the other end of which is connected to the second air port, wherein the minimum flow area of ​​the reference channel is smaller than the flow area of ​​the through hole.

[0030] Optionally, after acquiring the pressure value detected by the pressure sensor and determining whether the leakage of the oil tank exceeds the maximum permissible leakage based on the pressure value detected by the pressure sensor, the leakage diagnosis method further includes:

[0031] The oil tank's through-hole is connected to the atmosphere.

[0032] According to a second aspect of the present application, a leak diagnostic device is provided for a fuel evaporation system; the fuel evaporation system includes a fuel tank with a through hole; the leak diagnostic device further includes an air pump, a pressure sensor, and a controller; the air pump includes a first air port and a second air port communicating with the atmosphere; the pressure sensor is used to detect the air pressure inside the fuel tank.

[0033] The controller performs the leakage diagnosis method described above.

[0034] The leakage diagnosis method and device provided in this application, when diagnosing a fuel evaporation system, first test the leakage diagnosis device. With the leakage diagnosis device operating normally, pressure changes within the fuel evaporation system are then detected. This prevents the leakage detection from being affected by a malfunctioning leakage diagnosis device, ensuring the accuracy of the diagnosis. During leakage diagnosis, the controller controls the air pump to pump air into or out of the fuel tank. The controller can then determine whether the leakage in the fuel tank exceeds the maximum permissible leakage amount based on the pressure value detected by the pressure sensor. Therefore, the leakage diagnosis method provided in this application can determine the leakage status of the fuel tank based on changes in the air pressure within the tank. Since the air pressure within the fuel tank is almost unaffected by other factors, the pressure value detected by the pressure sensor has high accuracy, ensuring the accuracy of the diagnosis.

[0035] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0036] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0037] Figure 1 This is a schematic diagram of the structure of a fuel evaporation system and a leak diagnosis device provided in an embodiment of this application.

[0038] Figure 2 A flowchart of a method for diagnosing leaks in a fuel evaporation system provided in an embodiment of this application.

[0039] Figure 3 This is a schematic diagram of the reversing control valve of a leakage diagnostic device provided in an embodiment of this application in its first state.

[0040] Figure 4 This is a schematic diagram of the reversing control valve of a leakage diagnostic device provided in an embodiment of this application in its second state. Detailed Implementation

[0041] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0042] The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The singular forms “a,” “the,” and “the” used in this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0043] It should be understood that the terms "first," "second," and similar terms used in this application specification and claims do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, the terms "an" or "a" and similar terms do not indicate a quantity limitation, but rather indicate the presence of at least one. Unless otherwise stated, the terms "front," "rear," "lower," and / or "upper" and similar terms are for illustrative purposes only and are not limited to a location or spatial orientation. The terms "comprising" or "including" and similar terms mean that the elements or objects preceding "comprising" or "including" encompass the elements or objects listed following "comprising" or "including" and their equivalents, and do not exclude other elements or objects.

[0044] The following detailed description, with reference to the accompanying drawings, illustrates the method and apparatus for diagnosing leaks in a fuel evaporation system provided in this application. Unless otherwise specified, the features described in the embodiments and implementations can complement or combine with each other.

[0045] This application provides a method for diagnosing leaks in a fuel evaporation system, used to detect leaks in the fuel evaporation system. For example... Figure 1 As shown, the fuel evaporation system 10 includes a fuel tank 11 with a through hole 111. The leak diagnosis device 20 includes a controller 21, an air pump 22, and a pressure sensor 23; the air pump 22 includes a first air port 221 and a second air port 222 communicating with the atmosphere; the pressure sensor 23 is used to detect the air pressure inside the fuel tank 11. The leak diagnosis method is applied to the controller 21 of the leak diagnosis device 20.

[0046] like Figure 2 As shown, the leakage diagnosis method includes the following steps 110 to 130.

[0047] In step 110, it is checked whether the leak diagnostic device is working properly.

[0048] In step 120, if the leak diagnosis device is working normally, the second air port is connected to the through hole, and the air pump is put into operation so that the air pump pumps air to the oil tank or draws air from the oil tank through the through hole.

[0049] In step 130, the pressure value detected by the pressure sensor is collected, and the leakage of the oil tank is determined based on the pressure value detected by the pressure sensor to determine whether the leakage is greater than the maximum allowable leakage.

[0050] The leak diagnosis method provided in this application first tests the leak diagnosis device when diagnosing the fuel evaporation system. If the leak diagnosis device is working normally, then the pressure change within the fuel evaporation system is detected. This prevents the leak detection from being affected by the malfunctioning leak diagnosis device, ensuring the accuracy of the diagnosis. During the leak diagnosis process, the controller controls the air pump to pump air into or out of the fuel tank. The controller can then determine whether the leakage in the fuel tank exceeds the maximum permissible leakage amount based on the pressure value detected by the pressure sensor. Therefore, the leak diagnosis method provided in this application can determine the leakage status of the fuel tank based on changes in the air pressure within the tank. Since the air pressure within the fuel tank is almost unaffected by other factors, the pressure value detected by the pressure sensor is highly accurate, ensuring the accuracy of the diagnosis.

[0051] It should be noted that in the embodiments of this application, the pressure value detected by the pressure sensor is the relative pressure, that is, the pressure value detected by the pressure sensor is the absolute pressure minus the atmospheric pressure.

[0052] In one embodiment, such as Figure 1 As shown, the vehicle containing the fuel evaporation system includes a fuel evaporation system 10 and an engine 30. The vehicle containing the fuel evaporation system 10 is a pure gasoline-powered vehicle. The fuel evaporation system 10 also includes a carbon canister 12, a pipe connecting the carbon canister to the fuel tank, and a carbon canister purge valve 13. The carbon canister 12 includes a first connecting hole 121, a second connecting hole 122, and a third connecting hole 123. The first connecting hole 121 communicates with the through hole 111 of the fuel tank 11, the second connecting hole 122 communicates with the second air port 222 of the air pump 22, and the carbon canister purge valve 13 is located between the third connecting hole 123 and the engine 30. When the carbon canister purge valve 13 is open, the third connecting hole 123 is connected to the engine 30; when the carbon canister purge valve 13 is closed, the third connecting hole 123 is isolated from the engine 30. When the leak diagnostic device 20 performs a diagnostic, it controls the carbon canister purge valve 13 to close and controls the second air port 222 to communicate with the second connecting hole 122.

[0053] Since the fuel tank 11 and the carbon canister 12 are connected by a pipe connecting the carbon canister and the fuel tank, the gas pressure detected by the pressure sensor 23 in the fuel tank 11 is the same as the gas pressure in the carbon canister 12 and the gas pressure in the pipe connecting the carbon canister and the fuel tank. Therefore, the leakage amount of the fuel tank 11 in this embodiment is actually the total leakage amount of the fuel evaporation system 10.

[0054] In one embodiment, the controller 21 of the leak diagnostic device 20 may be an ECU (Electronic Control Unit). When the leak diagnostic device 20 is applied to a vehicle, the controller 21 may be an on-board controller.

[0055] In one embodiment, such as Figure 1 As shown, the leak diagnosis device 20 also includes a reversing control valve 24, which is disposed between the second air port 222 and the through hole 111. The reversing control valve 24 includes a first channel port 241, a second channel port 242, and a third channel port 243. The first channel port 241 communicates with the through hole 111 and is connected to the through hole 111 of the oil tank 11 via the carbon canister 12. The second channel port 242 communicates with the second air port 222, and the third channel port 243 is connected to the atmosphere. Figure 3 and Figure 4 As shown, the reversing control valve 24 has a first state and a second state, and the reversing control valve 24 in Figure 3In the first state shown, the first channel port 241 is connected to the third channel port 243, and the first channel port 241 is not connected to the second channel port 242; the reversing control valve 24 is in... Figure 4 In the second state shown, the first channel port 241 is connected to the second channel port 242, and the first channel port 241 is not connected to the third channel port 243.

[0056] In one embodiment, the reversing control valve 24 may be a two-position three-way solenoid reversing valve, which can switch between the first state and the second state by being de-energized or energized. For example, the two-position three-way reversing valve is in the first state when de-energized and in the second state when energized. Thus, switching the state can be achieved by energizing or de-energizing the reversing control valve 24, which is easy to operate.

[0057] In one embodiment, such as Figure 1 As shown, the leak diagnosis device 20 also includes a reference channel 25, one end of which is connected to the through hole 111 and the other end of which is connected to the second air port 222. The minimum flow area of ​​the reference channel 25 is smaller than the flow area of ​​the through hole 111.

[0058] In one embodiment, the leak diagnosis device 20 further includes a one-way flow element 27 located between the second air port 222 and the through hole 111. The flow direction of the one-way flow element 27 is the same as the flow direction of the airflow in the air pump 22. When the air pump 22 pumps air into the oil tank 11, the airflow in the air pump 22 flows from the second air port 222 to the through hole 111, and the flow direction of the one-way flow element 27 is also from the second air port 222 to the through hole 111. When the air pump 22 draws air from the oil tank 11, the airflow in the air pump 22 flows from the through hole 111 to the second air port 222, and the flow direction of the one-way flow element 27 is also from the through hole 111 to the second air port 222. In some embodiments, the one-way flow element 27 is a one-way valve.

[0059] In one embodiment, the vehicle housing the fuel evaporation system 10 further includes an air filter 26. The air filter 26 includes a first interface 261 and a second interface 262 communicating with the atmosphere. Atmospheric air enters the air filter 26 through the first interface 261 for filtration, and the filtered air exits the air filter 26 through the second interface 262. Gas entering the air filter 26 through the second interface 262 flows back to the atmosphere through the first interface 261. The first air port 211 is connected to the second interface 262. In the first state, the reversing control valve 24 connects the fuel tank 11 sequentially through the carbon canister 12, the first channel port 241, and the third channel port 243 to the second interface 262. In the second state, the second interface 262 connects to the fuel tank 11 sequentially through the air pump 22, the second channel port 242, the first channel port 241, and the carbon canister 12. The air filter 26 ensures air cleanliness and prevents impurities in the atmosphere from entering the fuel evaporation system 10 and the leak diagnosis device 20.

[0060] The following will describe in detail each step of the leakage diagnosis method provided in the embodiments of this application.

[0061] In step 110, it is checked whether the leak diagnostic device is working properly.

[0062] In one embodiment, before step 110, the leakage diagnosis method further includes: detecting vehicle information, determining whether the vehicle information meets the diagnostic conditions, and executing step 110 when it is determined that the vehicle information meets the diagnostic conditions.

[0063] In one embodiment, detecting vehicle information and determining whether the current vehicle information meets the diagnostic conditions specifically includes the following process:

[0064] First, the vehicle's current speed information is obtained. If the vehicle's current speed is less than or equal to a preset speed value, then the vehicle's current speed information meets the diagnostic criteria. The preset speed information can be 0 km / h or 5 km / h.

[0065] Subsequently, the vehicle's current power supply voltage information is obtained. If the vehicle's current power supply voltage information is within a preset voltage range, then the vehicle's current power supply voltage information is determined to meet the diagnostic conditions. The preset voltage range can be [10V, 14V].

[0066] Next, the vehicle's current gear information is obtained. If the vehicle's current gear information is a preset gear, then the vehicle's current gear information is determined to meet the diagnostic conditions. The preset gear can be P (Park) or Neutral.

[0067] Subsequently, the current status information of the vehicle's engine is acquired. If the current status information of the engine is within a preset range, the current gear information of the vehicle is determined to meet the diagnostic conditions. The current status information of the engine may include at least one of the engine's current speed, current coolant temperature, and current oil temperature.

[0068] Subsequently, the ambient temperature and ambient pressure information of the vehicle are obtained. If the ambient temperature of the vehicle is within the preset temperature range and the ambient pressure of the vehicle is within the preset pressure range, then the ambient temperature and ambient pressure of the vehicle are determined to meet the diagnostic conditions.

[0069] Subsequently, the current adsorption capacity of the carbon canister is obtained. If the current adsorption capacity of the carbon canister is less than the preset adsorption capacity, it is determined that the current adsorption capacity of the carbon canister meets the diagnostic conditions.

[0070] If all the vehicle information meets the diagnostic criteria, the controller executes step 110. If any vehicle information does not meet the diagnostic criteria, the controller terminates the execution of the leak diagnosis method.

[0071] In one embodiment, such as Figure 1 and Figure 2 As shown, step 110 of detecting whether the leak diagnostic device is working properly includes the following process:

[0072] First, control the air pump 22 to work and detect the current of the air pump 22. If the current of the air pump 22 increases, it is determined that the air pump 22 is working normally.

[0073] Subsequently, the air pump 22 is controlled to continue working, and the pressure value detected by the pressure sensor 23 is collected. If the absolute value of the collected pressure value increases, it is determined that the pressure sensor is working normally.

[0074] It can be seen that in step 110 of determining that the leak diagnosis device 20 is working properly, the air pump 22 and the pressure sensor 23 are tested respectively, which can prevent the air pump 22 or the pressure sensor 23 from failing to work properly and affecting the leak diagnosis of the fuel evaporation system 10.

[0075] When the air pump 22 is working normally, its current will gradually increase during the pumping process. When judging whether the air pump 22 is working properly based on its current, if the current of the air pump 22 does not increase or there is no current in the air pump 22, it can be determined that the air pump 22 has malfunctioned.

[0076] When the air pump 22 is operating normally, the pressure value detected by the pressure sensor 23 changes as it pumps air into or out of the oil tank 11. Specifically, when the air pump 22 pumps air into the oil tank 11, the gas pressure inside the oil tank 11 increases. If the pressure sensor 23 is operating normally, the pressure value detected by the pressure sensor 23 increases, and the absolute value of the pressure value detected by the pressure sensor 23 also increases. When the air pump 22 draws air from the oil tank 11, the gas pressure inside the oil tank 11 decreases. If the pressure sensor 23 is operating normally, the pressure value detected by the pressure sensor 23 decreases, and the absolute value of the pressure value detected by the pressure sensor 23 increases. Therefore, the controller 21's acquisition of an increase in the absolute value of the pressure value detected by the pressure sensor 23 confirms that the pressure sensor 23 is operating normally.

[0077] In one embodiment, when the leak diagnostic device 20 includes a reversing control valve 24, step 110 of detecting whether the leak diagnostic device 20 is working properly includes the following process:

[0078] First, control the reversing control valve 24 to be in the first state, and determine whether the air pump 22 is working properly.

[0079] In this step, when the reversing control valve 24 is in the first state, the first channel port 241 is connected to the third channel port 243, but not to the second channel port 242. When the air pump 22 is pumping air, the gas flows to the carbon canister 12 and the atmosphere through the reference channel 25. When the air pump 22 is evacuating air, air from the atmosphere flows into the air pump 22 through the third channel port 243, the first channel port 241, and the reference channel 25. Since the minimum flow area of ​​the reference channel 25 is smaller than the flow area of ​​the through hole 111, the airflow resistance is greater when the gas passes through the minimum flow area of ​​the reference channel 25 during the operation of the air pump 22, causing the current of the air pump 22 to rise faster, which is beneficial for quickly detecting the current change of the air pump 22.

[0080] Subsequently, if it is determined that the air pump 22 is working normally, the reversing control valve 24 is controlled to switch to the second state, and the air pump 22 is controlled to work, and the fourth pressure value detected by the pressure sensor 23 is collected.

[0081] In this step, when the control reversing valve 24 is in the second state, the first channel port 241 is connected to the second channel port 242, and the first channel port 241 is not connected to the third channel port 243. When the air pump 22 pumps air into the oil tank 11, some gas enters the oil tank 11 sequentially through the second channel port 242, the first channel port 241, and the carbon canister 12. At the same time, some gas enters the oil tank 11 sequentially through the reference channel 25 and the carbon canister 12. When the air pump 22 draws air from the oil tank 11, some gas in the oil tank 11 enters the air pump 22 sequentially through the carbon canister 12 and the reference channel 25, and is discharged to the atmosphere by the air pump 22. Some gas enters the air pump 22 sequentially through the carbon canister 12, the first channel port 241, and the second channel port 242, and is discharged to the atmosphere by the air pump 22.

[0082] Subsequently, if the absolute value of the fourth pressure value continues to increase, it is determined that the reversing control valve 24 and the pressure sensor 23 are working normally.

[0083] When the air pump 22 pumps air into the oil tank 11, if the reversing control valve 24 is working normally, the pressure of the gas in the oil tank 11 gradually increases, and the absolute value of the fourth pressure value continues to increase; when the air pump 22 draws air from the oil tank 11, if the reversing control valve 24 is working normally, the pressure of the gas in the oil tank 11 gradually decreases, and the pressure value detected by the pressure sensor 23 is negative, and the absolute value of the fourth pressure value continues to increase.

[0084] In step 120, if the leak diagnosis device is working normally, the second air port is connected to the through hole, and the air pump is put into operation so that the air pump pumps air to the oil tank or draws air from the oil tank through the through hole.

[0085] In this step, the controller 21 switches to the second state by controlling the reversing control valve 24 to achieve communication between the second air port 222 and the through hole 111. Specifically, when the reversing control valve 24 is in the second state, the first channel port 241 and the second channel port 242 are connected. When the air pump 22 pumps air into the oil tank 11, the gas flowing out of the second air port 222 enters the oil tank 11 in sequence through the second channel port 242, the first channel port 241, the carbon canister 12, and the through hole 111; when the air pump 22 draws air from the oil tank 11, the gas in the oil tank 11 flows into the air pump 22 in sequence through the through hole 111, the carbon canister 12, the first channel port 241, and the second channel port 242, and flows to the atmosphere through the air pump 22.

[0086] In step 130, the pressure value detected by the pressure sensor is collected, and the leakage of the oil tank is determined based on the pressure value detected by the pressure sensor to determine whether the leakage is greater than the maximum allowable leakage.

[0087] In one embodiment, step 130, which involves acquiring the pressure value detected by the pressure sensor and determining whether the leakage of the oil tank exceeds the maximum permissible leakage based on the pressure value detected by the pressure sensor, includes the following process:

[0088] First, when the absolute value of the first pressure value collected by the pressure sensor 23 is the first pressure threshold, the working time of the air pump 22 after it connects with the through hole from the second air port is obtained.

[0089] Subsequently, if the working time of the air pump 22 after it connects with the through hole from the second air port is less than or equal to the first time threshold, then it is determined that the leakage of the oil tank 11 is less than or equal to the maximum allowable leakage; wherein, the leakage of the oil tank 11 is the maximum allowable leakage, and when the absolute value of the first pressure value collected by the pressure sensor 23 is the first pressure threshold, the working time of the air pump 22 after it connects with the through hole from the second air port is the first time threshold.

[0090] In this embodiment, the leakage situation of the oil tank 11 is determined by obtaining the working time of the air pump 22 after it connects with the second air port and the through hole, and the working time is used as the basis for judgment. The judgment process is relatively simple. The working time of the air pump 22 after it connects with the second air port and the through hole refers to the time elapsed from when the air pump 22 starts working after the second air port connects with the through hole in step 120 until the absolute value of the first pressure value is the first pressure threshold.

[0091] In this embodiment, if the working time of the air pump 22 after it connects to the through hole from the second air port is greater than the first time threshold, then after determining that the leakage of the oil tank 11 is greater than the maximum allowable leakage, step 130 further includes the following process:

[0092] If the absolute value of the first pressure is equal to the first pressure threshold, and the operating time of the air pump 22 after connecting the second air port to the through hole is less than the first time threshold, it indicates that the pressure change rate of the fuel tank 11 is relatively fast, and the leakage of the fuel evaporation system 10 is small. If the absolute value of the first pressure is equal to the first pressure threshold, and the operating time of the air pump 22 after connecting the second air port to the through hole is greater than or equal to the first time threshold, it indicates that the pressure change rate of the fuel tank 11 is relatively slow, and the leakage of the fuel evaporation system 10 is relatively large. Therefore, the leakage of the fuel evaporation system 10 can be judged based on the operating time of the air pump 22 after connecting the second air port to the through hole.

[0093] In one embodiment, in step 130, the first duration threshold corresponding to the air pump 22 being in the air extraction working state and the first duration threshold corresponding to the air pump 22 being in the air pumping working state can be the same or different.

[0094] In one embodiment, the first duration threshold can be a duration range. "The operating time of the air pump 22 after it connects to the through hole after the second air port is less than the first duration threshold" means the minimum operating time of the air pump 22 after it connects to the through hole after the second air port is less than the first duration threshold; "The operating time of the air pump 22 after it connects to the through hole after the second air port is greater than or equal to the first duration threshold" means the maximum operating time of the air pump 22 after it connects to the through hole after the second air port is greater than or equal to the first duration threshold.

[0095] In one embodiment, the first duration threshold and the first pressure threshold may be values ​​pre-stored in the controller 21.

[0096] In one embodiment, the first pressure threshold and the first duration threshold can be determined by the following process:

[0097] A test tank with the same volume as the tank to be diagnosed was selected, and its leakage rate was set to the maximum permissible leakage rate. An air pump was used to pump or evacuate the test tank. After the air pump started operating, the pressure inside the test tank was measured at multiple time points. The duration between each measurement time point and the start time of the air pump was defined as the operating time of the air pump. The measured pressure in the test tank was a relative pressure. One of the operating times could be selected as the first time threshold, and the absolute value of the pressure corresponding to the first time threshold was defined as the first pressure threshold.

[0098] Furthermore, the air pump continuously pumps or evacuates air from the experimental oil tank until the absolute value of the pressure in the experimental oil tank reaches its maximum value. The working time of the air pump at this point is the maximum working time. The product of the absolute value of the maximum pressure and a coefficient (which is greater than 0 and less than 1) can be selected as the first pressure threshold, and the product of the maximum working time and the coefficient can be selected as the first duration threshold.

[0099] In another embodiment, step 130, which involves acquiring the pressure value detected by the pressure sensor and determining whether the leakage of the oil tank exceeds the maximum permissible leakage based on the pressure value detected by the pressure sensor, includes the following process:

[0100] When the working time of the air pump 22 after it connects to the through hole from the second air port is a first time threshold, the first pressure value detected by the pressure sensor 23 is collected.

[0101] If the absolute value of the first pressure value is less than the first pressure threshold, then the leakage of the oil tank 11 is determined to be greater than the maximum allowable leakage; wherein, the leakage of the oil tank 11 is the maximum allowable leakage, and when the absolute value of the first pressure value collected by the pressure sensor 23 is the first pressure threshold, the working time of the air pump after it connects with the through hole from the second air port is the first time threshold.

[0102] In this embodiment, the leakage of the oil tank 11 is determined by acquiring the first pressure value detected by the pressure sensor 23 when the working time of the air pump 22 after it connects with the second air port and the through hole reaches a first time threshold, and by using the absolute value of the first pressure value. The determination process is relatively simple. The working time of the air pump 22 after it connects with the second air port and the through hole refers to the time elapsed from when the air pump 22 starts working in step 120 until the absolute value of the first pressure reaches the first pressure threshold.

[0103] In this embodiment, step 130 further includes the following process: if the absolute value of the first pressure value is greater than or equal to the first pressure threshold, then it is determined that the leakage of the oil tank 11 is less than or equal to the maximum allowable leakage.

[0104] If the operating time of the air pump 22 after connecting the second air port to the through hole is the first time threshold, and the absolute value of the first pressure value is greater than or equal to the first pressure threshold, it indicates that the pressure change rate of the fuel tank 11 is relatively fast, and the leakage of the fuel evaporation system is small. If the operating time of the air pump 22 after connecting the second air port to the through hole is the first time threshold, and the absolute value of the first pressure value is less than the first pressure threshold, it indicates that the pressure change rate of the fuel tank 11 is relatively slow, and the leakage of the fuel evaporation system 10 is relatively large. Therefore, the leakage of the fuel evaporation system 10 can be judged based on the absolute value of the first pressure value.

[0105] In one embodiment, in step 130, the first duration threshold corresponding to the air pump 22 being in the air extraction working state and the first duration threshold corresponding to the air pump 22 being in the air pumping working state can be the same or different.

[0106] In one embodiment, the first pressure threshold can be a pressure range. "The absolute value of the first pressure value is greater than or equal to the first pressure threshold" means the maximum value of the first pressure value that is greater than or equal to the first pressure threshold; "The absolute value of the first pressure value is less than the first pressure threshold" means the minimum value of the first pressure value that is less than the first pressure threshold.

[0107] In one embodiment, the first duration threshold and the first pressure threshold may be values ​​pre-stored in the controller.

[0108] In one embodiment, the first pressure threshold and the first duration threshold can be determined by the following process:

[0109] A test tank with the same volume as the tank to be diagnosed was selected, and its leakage rate was set to the maximum permissible leakage rate. An air pump was used to pump or evacuate the test tank. After the air pump started operating, the pressure inside the test tank was measured at multiple time points. The duration between each measurement time point and the start time of the air pump was defined as the operating time of the air pump. The measured pressure in the test tank was a relative pressure. One of the operating times could be selected as the first time threshold, and the absolute value of the pressure corresponding to the first time threshold was defined as the first pressure threshold.

[0110] Furthermore, the air pump continuously pumps or evacuates air from the experimental oil tank until the absolute value of the pressure in the experimental oil tank reaches its maximum value. The operating time of the air pump at this point is the maximum operating time. The product of the absolute value of the maximum pressure and a coefficient (greater than 0 and less than 1) can be selected as the first pressure threshold, and the product of the maximum operating time and this coefficient can be selected as the first duration threshold. Further, the step of collecting the pressure value detected by the pressure sensor 23 and determining whether the leakage of the oil tank 11 exceeds the maximum permissible leakage based on the pressure value detected by the pressure sensor 23 also includes:

[0111] If the working time of the air pump 22 after it connects to the through hole from the second air port is a first time threshold, and the absolute value of the first pressure value is less than the first pressure threshold, it is determined that the leakage of the oil tank 11 is greater than the maximum allowable leakage.

[0112] The air pump 22 is controlled to continue working. When the working time of the air pump 22 after it connects with the through hole from the second air port reaches the second time threshold, the second pressure value detected by the pressure sensor 23 is collected; the second time threshold is greater than the first time threshold.

[0113] If the absolute value of the second pressure value is greater than or equal to the first pressure threshold, the leakage of the oil tank 11 is determined to be low leakage; the second duration threshold is greater than the first duration threshold; if the absolute value of the second pressure value is less than the first pressure threshold, the leakage of the oil tank 11 is determined to be high leakage.

[0114] When the leakage of the fuel tank exceeds the maximum allowable leakage, the fuel tank 11 is further inspected to determine whether the leakage of the fuel tank 11 is low or high. In other words, the leakage of the fuel tank 11 can be semi-quantitatively determined, which can achieve more accurate leakage diagnosis and facilitate the formulation of maintenance strategies for the fuel evaporation system 10.

[0115] In one embodiment, the second duration threshold can be determined by the following process: A tank with the same volume as the tank to be diagnosed is selected as the test tank, and the leakage rate of the test tank is the minimum value of the high leakage rate. An air pump is used to pump or evacuate the test tank, and the pressure value inside the test tank is detected. The second duration threshold is defined as the duration for which the absolute value of the pressure value inside the test tank equals the first pressure threshold. In another embodiment, step 130, which involves acquiring the pressure value detected by the pressure sensor and determining whether the leakage rate of the tank exceeds the maximum permissible leakage rate based on the pressure value detected by the pressure sensor, includes the following process:

[0116] First, when the working time of the air pump 22 after it connects with the through hole from the second air port is the third time threshold, the third pressure value detected by the pressure sensor is collected.

[0117] Subsequently, if the absolute value of the third pressure value is greater than the second pressure threshold, the air pump 22 is controlled to stop working, and the rate of change of the pressure value collected by the pressure sensor 23 over time is obtained. Based on the rate of change, it is determined whether the leakage of the oil tank 11 is greater than the maximum allowable leakage.

[0118] When the air pump 22 is stopped, since the flow direction of the one-way flow element 27 is the same as the flow direction of the airflow in the air pump 22, the one-way flow element 27 can prevent gas from flowing out of the oil tank 11 and also prevent external gas from flowing into the oil tank 11. Therefore, the gas in the oil tank 11 can only flow out through the leakage point of the oil tank 11 itself, and external gas can only flow into the oil tank 11 through the leakage point of the oil tank 11 itself. Therefore, the rate of change of the pressure value detected by the pressure sensor 23 reflects the amount of leakage in the oil tank 11.

[0119] In this step, the leakage situation of the oil tank 11 is determined by detecting the rate of change of pressure inside the oil tank 11. The determination process is relatively simple.

[0120] Further, the step of obtaining the rate of change of the pressure value collected by the pressure sensor 23 over time includes:

[0121] The pressure value collected by the pressure sensor 23 is obtained as a curve of pressure change over time, and the rate of change is determined based on the curve.

[0122] The controller 21 can collect pressure values ​​detected by the pressure sensor 23 at multiple time points, and obtain a pressure value change curve over time based on the multiple time points and the corresponding pressure values ​​at each time point. In some embodiments, the average slope of several points on the change curve can be determined as the rate of change of pressure in the oil tank 11 over time.

[0123] Furthermore, the process of acquiring the pressure value detected by the pressure sensor 23 and determining whether the leakage of the oil tank 11 exceeds the maximum permissible leakage based on the pressure value also includes the following steps:

[0124] First, when the working time of the air pump 22 after it connects with the through hole from the second air port is the third time threshold, the third pressure value detected by the pressure sensor 23 is collected.

[0125] Subsequently, if the absolute value of the third pressure value is less than the second pressure threshold, the leakage of the oil tank 11 is determined to be a high leakage.

[0126] If the leakage of the oil tank 11 is less than or equal to the minimum value of its corresponding high leakage, and the working time of the air pump 22 after it connects with the through hole from the second air port is the third time threshold, the third pressure value detected by the pressure sensor 23 is greater than or equal to the second pressure threshold.

[0127] In one embodiment, the second pressure threshold and the third duration threshold can be determined by the following process:

[0128] A test tank with the same volume as the tank to be diagnosed was selected, and its leakage rate was set to the minimum value for high leakage. An air pump was used to pump or evacuate the test tank. After the air pump started operating, the pressure inside the test tank was measured at multiple time points. The duration between each measurement time point and the start time of the air pump was defined as the pump's operating time. The measured pressure in the test tank was a relative pressure. One of the operating times could be selected as a third time threshold, and the absolute value of the pressure corresponding to the third time threshold was defined as the second pressure threshold.

[0129] Further, the air pump continuously pumps or evacuates air from the experimental oil tank until the absolute value of the pressure in the experimental oil tank reaches its maximum value. The operating time of the air pump at this point is the maximum operating time. The product of the absolute value of the maximum pressure and a coefficient (greater than 0 and less than 1) can be selected as the second pressure threshold, and the product of the maximum operating time and this coefficient can be selected as the third duration threshold. In one embodiment, after step 130, which involves acquiring the pressure value detected by the pressure sensor 23 and determining whether the leakage of the oil tank 11 exceeds the maximum permissible leakage based on the pressure value detected by the pressure sensor 23, the leakage diagnosis method further includes: controlling the through-hole of the oil tank to connect with the atmosphere. When the leakage diagnosis device includes the reversing control valve, the controller controls the reversing control valve to switch to a first state to achieve the connection of the through-hole of the oil tank with the atmosphere.

[0130] After step 130, controlling the through hole 111 of the fuel tank 11 to connect with the atmosphere can achieve pressure balance in the fuel tank 11 and ensure that the pressure in the fuel evaporation system 10 is normal during subsequent vehicle operation.

[0131] In one embodiment, there may be one or more leak points in the entire fuel evaporation system 10. These leak points can be equivalent to the leakage volume generated by a small orifice. Therefore, the maximum permissible leakage volume can be equivalent to the leakage volume generated by a small orifice of a certain diameter. The range of the maximum permissible leakage volume can be the leakage volume generated by a small orifice with a diameter of 0.3 mm to 1.0 mm. For example, the diameter of the small orifice can be 0.3 mm, 0.5 mm, 0.8 mm, 1.0 mm, etc.

[0132] In one embodiment, during steps 110 to 130, the leak diagnosis method further includes terminating the leak diagnosis process if a diagnostic termination condition is detected. The diagnostic termination condition includes: a control system malfunction; the number of leak diagnoses performed during a single driving trip reaching a maximum threshold; pressure fluctuations detected by the pressure sensor exceeding a set value; a sudden drop or rise in pressure detected by the pressure sensor to atmospheric pressure (this can occur if the fuel tank cap is opened); vehicle power supply voltage fluctuations exceeding a set value; no diagnosis performed within a specified time period; and fuel tank pressure increase exceeding a set value. In one embodiment, the vehicle containing the fuel evaporation system 10 also includes a display screen electrically connected to the controller 21. After step 130, the controller can send the diagnostic results to the display screen and control the display screen to display diagnostic information. Alternatively, the controller can be communicatively connected to an external electronic device, and after step 130, the controller can send the diagnostic results to the electronic device.

[0133] The above description is merely a preferred embodiment of this application and is not intended to limit this application in any way. Although this application has disclosed the preferred embodiment as above, it is not intended to limit this application. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the technical solution of this application. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of this application without departing from the content of the technical solution of this application shall still fall within the scope of the technical solution of this application.

[0134] This patent document discloses material protected by copyright. The copyright belongs to the copyright holder. The copyright holder does not object to anyone copying this patent document or the patent disclosure as it exists in the official records and archives of the Patent and Trademark Office.

Claims

1. A method of diagnosing a leak in a fuel vapor system, comprising: The fuel evaporation system includes a fuel tank with a through-hole; the leak diagnosis method is applied to the controller of a leak diagnosis device, which further includes an air pump and a pressure sensor; the air pump includes a first air port and a second air port communicating with the atmosphere; the pressure sensor is used to detect the air pressure inside the fuel tank; the leak diagnosis method includes: Check whether the leak diagnostic device is working properly; If the leak diagnosis device is working normally, it controls the second air port to connect with the through hole and controls the air pump to be in working state so that the air pump can pump air to the oil tank or draw air from the oil tank through the through hole; The pressure value detected by the pressure sensor is collected, and the leakage of the oil tank is determined based on the pressure value detected by the pressure sensor to determine whether the leakage is greater than the maximum allowable leakage. The process of acquiring the pressure value detected by the pressure sensor and determining whether the leakage of the oil tank exceeds the maximum permissible leakage based on the pressure value detected by the pressure sensor includes: When the absolute value of the first pressure value collected by the pressure sensor is a first pressure threshold, the working time of the air pump after it connects with the through hole from the second air port is obtained. If the operating time of the air pump after connecting the second air port to the through hole is less than or equal to a first time threshold, then the leakage of the oil tank is determined to be less than or equal to the maximum permissible leakage; wherein, the leakage of the oil tank is the maximum permissible leakage, and when the absolute value of the first pressure value collected by the pressure sensor is the first pressure threshold, the operating time of the air pump after connecting the second air port to the through hole is the first time threshold; or... The process of acquiring the pressure value detected by the pressure sensor and determining whether the leakage of the oil tank exceeds the maximum permissible leakage based on the pressure value detected by the pressure sensor includes: When the working time of the air pump after it connects with the through hole from the second air port is a first time threshold, the first pressure value detected by the pressure sensor is collected. If the absolute value of the first pressure value is less than the first pressure threshold, then the leakage of the oil tank is determined to be greater than the maximum permissible leakage; wherein, the leakage of the oil tank is the maximum permissible leakage, and when the absolute value of the first pressure value collected by the pressure sensor is the first pressure threshold, the operating time of the air pump after connecting from the second air port to the through hole is the first duration threshold; or... The leak diagnosis device further includes a one-way flow element located between the second air port and the through hole, the flow direction of the one-way flow element being the same as the flow direction of the airflow in the air pump; the step of acquiring the pressure value detected by the pressure sensor and determining whether the leakage of the oil tank exceeds the maximum permissible leakage based on the pressure value includes: When the working time of the air pump after it connects with the through hole from the second air port is a third time threshold, the third pressure value detected by the pressure sensor is collected. If the absolute value of the third pressure value is greater than the second pressure threshold, the air pump is controlled to stop working, and the rate of change of the pressure value collected by the pressure sensor over time is obtained. Based on the rate of change, it is determined whether the leakage of the oil tank is greater than the maximum allowable leakage.

2. The method for diagnosing leaks in a fuel evaporation system according to claim 1, characterized in that, When the working time of the air pump after it connects to the through hole from the second air port is a first time threshold, and the absolute value of the first pressure value is less than the first pressure threshold, after determining that the leakage of the oil tank is greater than the maximum permissible leakage, the step of collecting the pressure value detected by the pressure sensor and determining whether the leakage of the oil tank is greater than the maximum permissible leakage based on the pressure value detected by the pressure sensor further includes: The air pump is controlled to continue operating, and when the operating time of the air pump after it connects with the through hole from the second air port reaches a second time threshold, a second pressure value detected by the pressure sensor is collected; the second time threshold is greater than the first time threshold. If the absolute value of the second pressure value is greater than or equal to the first pressure threshold, the leakage of the oil tank is determined to be low leakage; if the absolute value of the second pressure value is less than the first pressure threshold, the leakage of the oil tank is determined to be high leakage.

3. The method for diagnosing leaks in a fuel evaporation system according to claim 1, characterized in that, The step of acquiring the rate of change of the pressure value collected by the pressure sensor over time includes: Obtain the pressure value collected by the pressure sensor over time, and determine the rate of change based on the curve.

4. The method for diagnosing leaks in a fuel evaporation system according to claim 1, characterized in that, The detection of whether the leak diagnostic device is working properly includes: Control the operation of the air pump, detect the current of the air pump, and if the current of the air pump increases, it is determined that the air pump is working normally; The air pump is controlled to continue working, and the pressure value detected by the pressure sensor is collected. If the absolute value of the collected pressure value increases, it is determined that the pressure sensor is working normally.

5. The method for diagnosing leaks in a fuel evaporation system according to claim 1, characterized in that, The leak diagnostic device further includes a reversing control valve disposed between the second air port and the through hole; the reversing control valve includes a first channel port, a second channel port, and a third channel port, the first channel port communicating with the through hole, the second channel port communicating with the second air port, and the third channel port communicating with the atmosphere; the reversing control valve has a first state and a second state, in the first state the first channel port and the third channel port are connected, and in the second state the first channel port and the second channel port are connected; detecting whether the leak diagnostic device is working properly includes: Control the reversing control valve to the first state and determine whether the air pump is working properly; If it is determined that the air pump is working normally, control the reversing control valve to switch to the second state, and control the air pump to work, and collect the fourth pressure value detected by the pressure sensor; If the absolute value of the fourth pressure value continues to increase, it is determined that the reversing control valve and the pressure sensor are working normally.

6. The method for diagnosing leaks in a fuel evaporation system according to claim 1, characterized in that, The leak diagnosis device further includes a reference channel, one end of which is connected to the through hole and the other end of which is connected to the second air port. The minimum flow area of ​​the reference channel is smaller than the flow area of ​​the through hole.

7. The method for diagnosing leaks in a fuel evaporation system according to claim 1, characterized in that, After acquiring the pressure value detected by the pressure sensor and determining whether the leakage of the oil tank exceeds the maximum permissible leakage based on the pressure value detected by the pressure sensor, the leakage diagnosis method further includes: The oil tank's through-hole is connected to the atmosphere.

8. A leak diagnosis device, characterized in that, The leak diagnostic device is used in a fuel evaporation system; the fuel evaporation system includes a fuel tank with a through hole; the leak diagnostic device also includes an air pump, a pressure sensor, and a controller; the air pump includes a first air port and a second air port communicating with the atmosphere; the pressure sensor is used to detect the air pressure inside the fuel tank; The controller performs the leakage diagnosis method according to any one of claims 1 to 7.

Images