Method for diagnosing a leak in a fuel vapor system and leak diagnosing apparatus

Abstract

The application provides a leakage diagnosis method and device for a fuel evaporation system. The fuel evaporation system comprises an oil tank provided with a first through hole, a carbon canister provided with a second through hole and a third through hole, and an isolation valve. The leakage diagnosis device comprises a controller, an air pump and a pressure sensor. The leakage diagnosis method comprises the following steps: detecting whether the leakage diagnosis device and the isolation valve are normal; if the leakage diagnosis device and the isolation valve are normal, the third through hole is controlled to be not communicated with the atmosphere, the isolation valve is controlled to be closed, and the air pump is controlled to work, so that the air pump pumps or exhausts air to the carbon canister; collecting a pressure value of the carbon canister detected by the pressure sensor, and judging whether the leakage amount of the carbon canister is greater than the maximum allowable leakage amount according to the detected pressure value; if the leakage amount of the carbon canister is less than or equal to the maximum allowable leakage amount, the isolation valve is controlled to be opened, the air pump is controlled to work, a pressure value of the fuel evaporation system detected is collected, and whether the leakage amount of the fuel evaporation system is greater than the maximum allowable leakage amount is judged according to the detected pressure value.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of automobiles, in particular to a leakage diagnosis method and a leakage diagnosis device of a fuel evaporation system. BACKGROUND

[0002] With the increase of the number of automobiles, automobile pollution has become an important source of air pollution and an important cause of fine particulate matter and photochemical smog pollution.

[0003] When the fuel evaporation system of an automobile leaks, fuel vapor will enter the air, causing air pollution. Therefore, it is necessary to detect whether the fuel evaporation system of the automobile has a leakage that exceeds the allowable range. SUMMARY

[0004] According to a first aspect of an embodiment of the present application, a leakage diagnosis method of a fuel evaporation system is provided. The fuel evaporation system comprises a fuel tank, a carbon canister and an isolation valve, the fuel tank is provided with a first through hole, the carbon canister is provided with a second through hole and a third through hole, and the isolation valve is arranged between the first through hole and the second through hole. The leakage diagnosis method is applied to a controller of a leakage diagnosis device, and the leakage diagnosis device further comprises a gas pump and a pressure sensor. The gas pump comprises a first gas port and a second gas port which are in communication with the atmosphere. The pressure sensor is used to detect the gas pressure of the fuel evaporation system. The leakage diagnosis method comprises the following steps.

[0005] Detecting whether the leakage diagnosis device and the isolation valve are working normally;

[0006] If the leakage diagnosis device and the isolation valve are working normally, controlling the third through hole to be not in communication with the atmosphere, controlling the isolation valve to be closed, and controlling the gas pump to be in a working state, so that the gas pump pumps gas to or from the carbon canister through the third through hole;

[0007] Collecting the pressure value of the carbon canister detected by the pressure sensor, and judging whether the leakage amount of the carbon canister is greater than the maximum allowable leakage amount of the carbon canister according to the pressure value of the carbon canister detected by the pressure sensor;

[0008] If the leakage amount of the carbon canister is less than or equal to the maximum allowable leakage amount of the carbon canister, controlling the isolation valve to be opened, controlling the gas pump to continue to work, collecting the pressure value of the fuel evaporation system detected by the pressure sensor, and judging whether the leakage amount of the fuel evaporation system is greater than the maximum allowable leakage amount of the fuel evaporation system according to the pressure value of the fuel evaporation system detected by the pressure sensor.

[0009] Optionally, the collecting the pressure value detected by the pressure sensor and determining whether the leakage of the fuel evaporation system is greater than the maximum allowable leakage of the fuel evaporation system according to the pressure value of the fuel evaporation system detected by the pressure sensor comprises:

[0010] when the absolute value of the first pressure value of the fuel evaporation system collected by the pressure sensor is the first pressure threshold, obtaining the working time length of the air pump after the isolation valve is opened;

[0011] if the working time length of the air pump after the isolation valve is opened is less than or equal to the first time length threshold, it is determined that the leakage of the fuel evaporation system is less than or equal to the maximum allowable leakage of the fuel evaporation system; wherein, when the leakage of the fuel evaporation system is the maximum allowable leakage of the fuel evaporation system and the absolute value of the first pressure value of the fuel evaporation system collected by the pressure sensor is the first pressure threshold, the working time length of the air pump after the isolation valve is opened is the first time length threshold; or,

[0012] the collecting the pressure value detected by the pressure sensor and determining whether the leakage of the fuel evaporation system is greater than the maximum allowable leakage of the fuel evaporation system according to the pressure value of the fuel evaporation system detected by the pressure sensor comprises:

[0013] when the working time length of the air pump after the isolation valve is opened is the first time length threshold, collecting the first pressure value of the fuel evaporation system detected by the pressure sensor;

[0014] if the absolute value of the first pressure value is less than the first pressure threshold, it is determined that the leakage of the fuel evaporation system is greater than the maximum allowable leakage; wherein, when the leakage of the fuel evaporation system is the maximum allowable leakage of the fuel evaporation system and the absolute value of the first pressure value of the fuel evaporation system collected by the pressure sensor is the first pressure threshold, the working time length of the air pump after the isolation valve is opened is the first time length threshold.

[0015] Optionally, when the working time length of the air pump after the isolation valve is opened is the first time length threshold and the absolute value of the first pressure value is less than the first pressure threshold, after it is determined that the leakage of the fuel evaporation system is greater than the maximum allowable leakage of the fuel evaporation system, the collecting the pressure value detected by the pressure sensor and determining whether the leakage of the fuel evaporation system is greater than the maximum allowable leakage of the fuel evaporation system according to the pressure value of the fuel evaporation system detected by the pressure sensor further comprises:

[0016] controlling the air pump to continue to work, and when a working time of the air pump since the isolation valve is opened reaches a second time threshold, collecting a second pressure value of the fuel evaporation system detected by the pressure sensor; the second time threshold is greater than the first time threshold;

[0017] If an absolute value of the second pressure value is greater than or equal to the first pressure threshold, it is determined that the leakage amount of the fuel evaporation system is a low leakage amount; if the absolute value of the second pressure value is less than the first pressure threshold, it is determined that the leakage amount of the fuel evaporation system is a high leakage amount.

[0018] Optionally, the collecting the pressure value of the carbon canister detected by the pressure sensor and determining whether the leakage amount of the carbon canister is greater than the maximum allowable leakage amount of the carbon canister according to the pressure value of the carbon canister detected by the pressure sensor comprises:

[0019] When the pressure value of the carbon canister detected by the pressure sensor reaches a stable state, collecting a third pressure value of the carbon canister detected by the pressure sensor;

[0020] When an absolute value of the third pressure value is greater than or equal to a second pressure threshold, it is determined that the leakage amount of the carbon canister is less than or equal to the maximum allowable leakage amount of the carbon canister; wherein the leakage amount of the carbon canister is the maximum allowable leakage amount of the carbon canister, and when the pressure value of the carbon canister detected by the pressure sensor reaches the stable state, the absolute value of the third pressure value is the second pressure threshold.

[0021] Optionally, the leakage diagnosis device further comprises a reference channel and a reversing control valve, the reversing control valve is arranged between the second air port and the third through hole; the reversing control valve comprises a first channel port, a second channel port and a third channel port, the first channel port is in communication with the third through hole, the second channel port is in communication with the second air port, and the third channel port is in communication with the atmosphere; the reversing control valve has a first state and a second state, when the reversing control valve is in the first state, the first channel port is in communication with the third channel port, and when the reversing control valve is in the second state, the first channel port is in communication with the second channel port; one end of the reference channel is in communication with the second air port, and the other end is in communication with the third through hole;

[0022] The leakage diagnosis method further comprises:

[0023] controlling the reversing control valve to switch to the first state, and when a fourth pressure value between a position where a flow area of the reference channel is minimum and the second air port reaches a stable state, acquiring the fourth pressure value; an air intake amount at the position where the flow area of the reference channel is minimum is less than or equal to the maximum allowable leakage amount of the carbon canister;

[0024] The absolute value of the fourth pressure value is determined as the second pressure threshold value.

[0025] Optionally, the inner diameter of the position with the minimum flow area of the reference channel ranges from 0.3 mm to 1.0 mm.

[0026] Optionally, the detection of whether the leakage diagnosis device and the isolation valve are working normally comprises:

[0027] The gas pump is controlled to work, and the current of the gas pump is detected; if the current of the gas pump increases, it is determined that the gas pump is working normally.

[0028] The carbon canister is controlled to be disconnected from the atmosphere, the gas pump is controlled to continue working, the isolation valve is controlled to be opened, and the pressure value detected by the pressure sensor is collected; if the absolute value of the pressure value detected by the pressure sensor increases, it is determined that the isolation valve and the pressure sensor are working normally.

[0029] Optionally, the leakage diagnosis device further comprises a reversing control valve, which is arranged between the second gas port and the third through hole; the reversing control valve comprises a first channel port, a second channel port and a third channel port, the first channel port is in communication with the third through hole, the second channel port is in communication with the second gas port, and the third channel port is in communication with the atmosphere; the reversing control valve has a first state and a second state; when the reversing control valve is in the first state, the first channel port is in communication with the third channel port; when the reversing control valve is in the second state, the first channel port is in communication with the second channel port.

[0030] The control of the third through hole and the atmosphere comprises: the reversing control valve is switched to the second state; and the gas pump pumps air to or from the carbon canister through the second channel port, the first channel port and the third through hole in sequence.

[0031] Optionally, after the pressure value of the fuel evaporation system detected by the pressure sensor is collected, and it is determined whether the leakage amount of the fuel evaporation system is greater than the maximum allowable leakage amount of the fuel evaporation system according to the pressure value of the fuel evaporation system detected by the pressure sensor, the leakage diagnosis method further comprises:

[0032] The isolation valve is controlled to be opened, and the third through hole is controlled to be in communication with the atmosphere.

[0033] According to a second aspect of the embodiments of the present application, a leakage diagnosis device is provided, which is used for a fuel evaporation system; the fuel evaporation system comprises a fuel tank, a carbon canister and an isolation valve, the fuel tank is provided with a first through hole, the carbon canister is provided with a second through hole and a third through hole, and the isolation valve is arranged between the first through hole and the second through hole; the leakage diagnosis device comprises an air pump, a pressure sensor and a controller; the air pump comprises a first air port and a second air port which are in communication with the atmosphere; the pressure sensor is used for detecting the air pressure of the fuel evaporation system.

[0034] The controller executes the leakage diagnosis method described above.

[0035] The leakage diagnosis method and the leakage diagnosis device provided by the embodiments of the present application can prevent the leakage diagnosis device and the isolation valve from affecting the leakage detection of the fuel evaporation system when the leakage diagnosis device and the isolation valve cannot work normally, and ensure the accuracy of diagnosis; during the leakage diagnosis process, the controller controls the air pump to pump air to the fuel evaporation system or to pump air out of the fuel evaporation system, so that the controller can determine whether the leakage of the carbon canister is greater than the maximum allowable leakage of the carbon canister according to the pressure value of the carbon canister detected by the pressure sensor, and determine whether the leakage of the fuel evaporation system is greater than the maximum allowable leakage of the fuel evaporation system according to the pressure value of the fuel evaporation system detected by the pressure sensor when the leakage of the carbon canister is less than or equal to the maximum allowable leakage of the carbon canister; since the leakage of the fuel evaporation system is not greater than the maximum allowable leakage of the fuel evaporation system only when the leakage of the carbon canister is less than or equal to the maximum allowable leakage of the carbon canister, detecting the leakage of the carbon canister first helps to improve the accuracy of detecting the leakage of the fuel evaporation system. The leakage diagnosis method provided by the embodiments of the present application can determine the leakage of the fuel evaporation system according to the pressure value of the fuel evaporation system, and since the pressure value in the fuel evaporation system is hardly affected by other factors, the accuracy of the pressure value detected by the pressure sensor is high, and the accuracy of diagnosis can be ensured.

[0036] It should be understood that the general description above and the detailed description below are only exemplary and explanatory, and cannot limit the present application. BRIEF DESCRIPTION OF DRAWINGS

[0037] The accompanying drawings, which are incorporated into and form part of the specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the application.

[0038] Figure 1 The structure schematic diagram of the fuel evaporation system and the leakage diagnosis device provided by an embodiment of the present application.

[0039] Figure 2 A flow chart of a leak diagnosis method of a fuel vapor system is provided for an embodiment of the present application.

[0040] Figure 3 A schematic view of a reversing control valve of a leak diagnosis device in a first state is provided for an embodiment of the present application.

[0041] Figure 4 A schematic view of a reversing control valve of a leak diagnosis device in a second state is provided for an embodiment of the present application. DETAILED DESCRIPTION

[0042] The exemplary embodiments will be described in detail herein with reference to the attached drawings. The description of the exemplary embodiments is intended to apply to all alternative embodiments, as would be understood by persons skilled in the art. To the extent that they do not particularize to the application, the following description of exemplary embodiments is provided for illustration purposes to facilitate a better understanding of the application.

[0043] The terminology used in the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application. As used in the description of the embodiments and the appended claims, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0044] It should be understood that "first", "second", and similar terms used herein are not intended to denote a particular order, quantity, or importance, but are used to distinguish one component from another. Similarly, "one" or "a" or similar terms are not intended to denote a quantity of one, but are used to denote that at least one exists. Unless otherwise indicated, "front", "back", "under", and / or "over" and similar terms are used to indicate relative positioning, not absolute positioning. "Include" or "comprise" and similar terms are meant to encompass the elements listed thereafter, as well as their equivalents, and do not preclude other elements.

[0045] The leak diagnosis method of a fuel vapor system and the leak diagnosis device of the embodiments of the present application will be described in detail below with reference to the accompanying drawings. The features of the embodiments and the implementation modes described below can be supplemented or combined with each other, without conflict.

[0046] The embodiments of the present application provide a leak diagnosis method of a fuel vapor system, which is used to detect the leakage of the fuel vapor system. As shown in Figure 1As shown in the figure, the fuel evaporation system 10 comprises a fuel tank 11, a carbon canister 12 and an isolation valve 13, the fuel tank 11 is provided with a first through hole 111, the carbon canister 12 is provided with a second through hole 121 and a third through hole 122, and the isolation valve 13 is arranged between the first through hole 111 and the second through hole 121. The leakage diagnosis device 20 comprises a controller 21, an air pump 22 and a pressure sensor 23. The air pump 22 comprises a first air port 221 and a second air port 222 which are in communication with the atmosphere. The pressure sensor 23 is used to detect the air pressure of the fuel evaporation system 10. The leakage diagnosis method is applied to the controller 21 of the leakage diagnosis device 20.

[0047] As shown in the figure, the leakage diagnosis method comprises the following steps 110 to 140. Figure 2

[0048] In step 110, it is detected whether the leakage diagnosis device and the isolation valve are working normally.

[0049] In step 120, if the leakage diagnosis device and the isolation valve are working normally, the third through hole is controlled to be not in communication with the atmosphere, the isolation valve is controlled to be closed, and the air pump is controlled to be in working state, so that the air pump pumps air to or from the carbon canister through the third through hole.

[0050] In step 130, the pressure value of the carbon canister detected by the pressure sensor is collected, and it is judged whether the leakage amount of the carbon canister is greater than the maximum allowable leakage amount of the carbon canister according to the pressure value of the carbon canister detected by the pressure sensor.

[0051] In step 140, if the leakage amount of the carbon canister is less than or equal to the maximum allowable leakage amount of the carbon canister, the isolation valve is controlled to be opened, the air pump is controlled to continue working, the pressure value of the fuel evaporation system detected by the pressure sensor is collected, and it is judged whether the leakage amount of the fuel evaporation system is greater than the maximum allowable leakage amount of the fuel evaporation system according to the pressure value of the fuel evaporation system detected by the pressure sensor.

[0052] ​The leakage diagnosis method provided in the embodiments of the present application can prevent the leakage diagnosis device and the isolation valve from affecting the leakage detection of the fuel evaporation system when the leakage diagnosis device and the isolation valve cannot work normally, and ensure the accuracy of diagnosis; during the leakage diagnosis process, the controller controls the air pump to pump air to the fuel evaporation system or to pump air out of the fuel evaporation system, so that the controller can determine whether the leakage amount of the carbon canister is greater than the maximum allowable leakage amount of the carbon canister according to the pressure value of the carbon canister detected by the pressure sensor, and determine whether the leakage amount of the fuel evaporation system is greater than the maximum allowable leakage amount of the fuel evaporation system according to the pressure value of the fuel evaporation system detected by the pressure sensor when the leakage amount of the carbon canister is less than or equal to the maximum allowable leakage amount of the carbon canister; since the leakage amount of the fuel evaporation system is not greater than the maximum allowable leakage amount of the fuel evaporation system only when the leakage amount of the carbon canister is less than or equal to the maximum allowable leakage amount of the carbon canister, detecting the leakage amount of the carbon canister first helps to improve the accuracy of the detection of the leakage condition of the fuel evaporation system. The leakage diagnosis method provided in the embodiments of the present application can determine the leakage condition of the fuel evaporation system according to the pressure value of the fuel evaporation system, and since the pressure value in the fuel evaporation system is almost not affected by other factors, the accuracy of the pressure value detected by the pressure sensor is high, and the accuracy of diagnosis can be ensured.

[0053] It should be noted that in the embodiments of the present application, the pressure value detected by the pressure sensor is a relative pressure, that is, the pressure value detected by the pressure sensor is the value of the absolute pressure minus the atmospheric pressure.

[0054] In the embodiments of the present application, the maximum allowable leakage amount of the carbon canister and the maximum allowable leakage amount of the fuel evaporation system can be the same, or the maximum allowable leakage amount of the carbon canister is less than the maximum allowable leakage amount of the fuel evaporation system.

[0055] In one embodiment, as Figure 1As shown, the vehicle in which the fuel evaporation system is located comprises the fuel evaporation system 10 and the engine 30, and the vehicle in which the fuel evaporation system 10 is located is a plug-in hybrid vehicle. The fuel evaporation system 10 further comprises a pipe connecting the carbon canister and the fuel tank and a carbon canister purge valve 14. The carbon canister 12 further comprises a fourth through hole 123. An isolation valve 13 is arranged between the first through hole 111 and the second through hole 121, and when the isolation valve 13 is opened, the first through hole 111 and the second through hole 121 are in communication, i.e. the fuel tank 11 and the carbon canister 12 are in communication; when the isolation valve 13 is closed, the first through hole 111 and the second through hole 121 are not in communication, i.e. the fuel tank 11 and the carbon canister 12 are isolated. The third through hole 122 is in communication with the second air port 222 of the air pump 22. The carbon canister purge valve 14 is located between the fourth through hole 123 and the engine 30. When the carbon canister purge valve 14 is opened, the fourth through hole 123 and the engine 30 are in communication; when the carbon canister purge valve 14 is closed, the fourth through hole 123 and the engine 30 are isolated. When the carbon canister is diagnosed, the controller 21 of the leak diagnosis device 20 controls the isolation valve 13 and the carbon canister purge valve 14 to be closed and controls the second air port 222 and the third through hole 122 to be in communication; when the leak of the fuel evaporation system 10 is diagnosed, the controller 21 controls the isolation valve 13 to be opened, controls the carbon canister purge valve 14 to be closed, and controls the second air port 222 and the third through hole 122 to be in communication.

[0056] Since the fuel tank 11 and the carbon canister 12 are in communication through the pipe connecting the carbon canister and the fuel tank, the gas pressure in the fuel tank 11 detected by the pressure sensor 23 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, and the leak amount of the fuel evaporation system 10 of the embodiment of the present application includes the leak amount of the fuel tank 11, the leak amount of the carbon canister 12 and the leak amount of the pipe in the fuel evaporation system 10.

[0057] In one embodiment, the controller 21 of the leak diagnosis device 20 can be an ECU (Electronic Control Unit). When the leak diagnosis device 20 is applied to a vehicle, the controller 21 can be a vehicle-mounted controller.

[0058] In one embodiment, as shown in FIG. 2, the fuel evaporation system 10 further comprises a fuel tank pressure sensor 24 arranged in the fuel tank 11. Figure 1As shown, the leakage diagnosis device 20 further comprises a reversing control valve 25, which is arranged between the second gas port 222 and the third through hole 122; the reversing control valve 25 comprises a first passage port 251, a second passage port 252 and a third passage port 253, the first passage port 251 is in communication with the first through hole 111, the first passage port 251 is in communication with the first through hole 111 of the oil tank 11 through the carbon canister 12; the second passage port 252 is in communication with the second gas port 222, and the third passage port 253 is in communication with the atmosphere. As Figure 3 and Figure 4 As shown, the reversing control valve 25 has a first state and a second state, the reversing control valve 25 is in the first state as shown, the first passage port 251 is in communication with the third passage port 253, and the first passage port 251 is not in communication with the second passage port 252; the reversing control valve 25 is in the second state as shown, the first passage port 251 is in communication with the second passage port 252, and the first passage port 251 is not in communication with the third passage port 253. Figure 3 Figure 4

[0059] In one embodiment, the reversing control valve 25 can be a two-position three-way electromagnetic reversing valve, which can be switched between the first state and the second state by power-off or power-on. For example, the two-position three-way reversing valve is in the first state when power-off, and is in the second state when power-on. In this way, the reversing control valve 25 is powered on or powered off to realize the switching of the state, which is easy to operate.

[0060] In one embodiment, as shown, Figure 1 The leakage diagnosis device 20 further comprises a reference passage 26, one end of the reference passage 26 is in communication with the third through hole 122, the other end of the reference passage 26 is in communication with the second gas port 222, and the air flow at the position of the minimum flow area of the reference passage 26 is less than or equal to the maximum allowable leakage amount of the carbon canister.

[0061] In one embodiment, the inner diameter of the position of the minimum flow area of the reference passage 26 ranges from 0.3mm to 1.0mm. For example, the inner diameter of the position of the minimum flow area of the reference passage 26 is 0.3mm, 0.5mm, 0.7mm, 0.9mm, 1.0mm, etc.

[0062] In one embodiment, as shown, Figure 1 ​​As shown, the fuel evaporation system 10 includes two pressure sensors 23: a first pressure sensor 231 and a second pressure sensor 241, wherein the first pressure sensor 231 is arranged between the second air port 222 and the position where the flow area of the reference channel is the smallest, and the second pressure sensor 241 is arranged in the fuel tank 11. In other embodiments, the fuel evaporation system 10 is provided with one pressure sensor 23, which is arranged on the side of the isolation valve 13 away from the fuel tank 11 and between the second air port 222 and the position where the flow area of the reference channel is the smallest, so that the pressure can detect the pressure of the carbon canister 12, the pressure between the second air port 222 and the position where the flow area of the reference channel is the smallest, and the pressure of the fuel tank 11.

[0063] In one embodiment, the vehicle in which the fuel evaporation system 10 is arranged further includes an air filtering device 27, which includes a first interface 271 and a second interface 272 that are in communication with the atmosphere, air in the atmosphere enters the air filtering device 27 for filtering through the first interface 271, and filtered air can flow out of the air filtering device 27 through the second interface 272; gas entering the air filtering device 27 through the second interface 272 can flow to the atmosphere through the first interface 271. The first air port 211 is in communication with the second interface 272. When the reversing control valve 25 is in the first state, the fuel tank 11 is in communication with the second interface 272 through the carbon canister 12, the first channel port 251 and the third channel port 253 in sequence; when the reversing control valve 25 is in the second state, the second interface 272 is in communication with the fuel tank 11 through the air pump 22, the second channel port 252, the first channel port 251 and the carbon canister 12 in sequence. The air filtering device 27 can ensure the cleanliness of the air and prevent impurities in the atmosphere from entering the fuel evaporation system 10 and the leak diagnosis device 20.

[0064] The steps of the leak diagnosis method provided by the embodiments of the present application will be described in detail below.

[0065] In step 110, it is detected whether the leak diagnosis device is working normally.

[0066] In one embodiment, before step 110, the leak diagnosis method further includes: detecting vehicle information and determining whether the vehicle information meets diagnosis conditions, and when it is determined that the vehicle information meets the diagnosis conditions, step 110 is performed.

[0067] In one embodiment, the detection of the vehicle information and the determination of whether the current vehicle information of the vehicle meets the diagnosis conditions specifically include the following process:

[0068] 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.

[0069] 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].

[0070] 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.

[0071] 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.

[0072] 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.

[0073] 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.

[0074] 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.

[0075] 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:

[0076] First, control the air pump to work and detect the current of the air pump. If the current of the air pump increases, it is determined that the air pump is working normally.

[0077] Subsequently, the carbon canister is disconnected from the atmosphere, the air pump continues to operate, and the isolation valve is opened. 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 isolation valve and the pressure sensor are working normally.

[0078] It can be seen that in the step 110 of judging whether the leakage diagnosis device 20 is normal, the air pump 22, the isolation valve 13 and the pressure sensor 23 are detected respectively, so that the leakage diagnosis of the fuel evaporation system 10 can be affected by the air pump 22, the isolation valve 13 and the pressure sensor 23 which cannot work normally.

[0079] When the air pump continues to work and the isolation valve is controlled to be opened, the carbon canister is controlled to be not communicated with the atmosphere. When the air pump 22 works normally, the current of the air pump 22 will gradually increase during the pumping process. When the air pump 22 is judged to be normal according to the current of the air pump 22, if it is detected that 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 is faulty.

[0080] When the air pump 22 works normally and the isolation valve 13 is closed, the pressure value of the carbon canister 12 detected by the first pressure sensor 231 will change when the air pump 22 pumps air into the carbon canister 12 or pumps air out of the carbon canister 12. Specifically, when the air pump 22 pumps air into the carbon canister 12, the gas pressure in the carbon canister 12 increases, and if the first pressure sensor 231 works normally, the pressure value of the carbon canister 12 detected by the first pressure sensor 231 increases, and the absolute value of the pressure value detected by the first pressure sensor 231 increases; when the air pump 22 pumps air out of the carbon canister 12, the gas pressure in the carbon canister 12 decreases, and if the first pressure sensor 231 works normally, the pressure value of the carbon canister 12 detected by the first pressure sensor 231 decreases, and the absolute value of the pressure value of the carbon canister 12 detected by the first pressure sensor 231 increases.

[0081] When the air pump 22 continues to work and the isolation valve 13 is controlled to be opened, the carbon canister 12 is communicated with the fuel tank 11, and the pressure value detected by the second pressure sensor 241 will change when the air pump 22 pumps air into the fuel tank 11 or pumps air out of the fuel tank 11. Specifically, when the air pump 22 pumps air into the fuel tank 11, the gas pressure in the fuel tank 11 increases, and if the second pressure sensor 241 works normally, the pressure value detected by the second pressure sensor 241 increases, and the absolute value of the pressure value detected by the second pressure sensor 241 increases; when the air pump 22 pumps air out of the fuel tank 11, the gas pressure in the fuel tank 11 decreases, and if the second pressure sensor 241 works normally, the pressure value detected by the second pressure sensor 241 decreases, and the absolute value of the pressure value detected by the second pressure sensor 241 increases.

[0082] Therefore, the controller 21 can determine that the first pressure sensor 231 and the second pressure sensor 241 work normally according to the absolute value of the pressure value detected by the first pressure sensor 231 and the second pressure sensor 241.

[0083] In one embodiment, when the leakage diagnosis device 20 comprises the reversing control valve 25, the first pressure sensor 231 and the second pressure sensor 241, the step 110 of detecting whether the leakage diagnosis device and the isolation valve are working normally comprises the following process:

[0084] Firstly, the reversing control valve 25 is controlled to be in the first state, and whether the air pump 22 is working normally is determined.

[0085] In this step, when the reversing control valve 25 is in the first state, the first passage port 251 is communicated with the third passage port 253, and the first passage port 251 is not communicated with the second passage port 252. When the air pump 22 pumps air, the gas flows to the carbon canister 12 and the atmosphere through the reference passage 26. When the air pump 22 pumps air, the air in the atmosphere flows into the air pump 22 through the third passage port 253, the first passage port 251 and the reference passage 26. Since the minimum flow area of the reference passage 26 is small, the gas flow resistance is large when the gas passes through the minimum flow area of the reference passage 26 when the air pump 22 works, so that the current of the air pump 22 rises quickly, which is beneficial to quickly detect the current change of the air pump 22.

[0086] Subsequently, if it is determined that the air pump 22 is working normally, the reversing control valve 25 is controlled to switch to the second state, the isolation valve 13 is controlled to be opened, and the air pump 22 is controlled to work, and the pressure value detected by the first pressure sensor 231 and the pressure value detected by the second pressure sensor 241 are collected.

[0087] In this step, when the reversing control valve 25 is in the second state, the first passage port 251 is communicated with the second passage port 252, and the first passage port 251 is not communicated with the third passage port 253. When the air pump 22 pumps air to the fuel evaporation system 10, part of the gas enters the carbon canister 12 and the fuel tank 11 in turn through the second passage port 252 and the first passage port 251, and part of the gas enters the carbon canister 12 and the fuel tank 11 in turn through the reference passage 26. When the air pump 22 pumps air from the fuel evaporation system 10, part of the gas in the fuel tank 11 enters the air pump 22 in turn through the carbon canister 12 and the reference passage 26, and is discharged into the atmosphere through the air pump 22. Part of the gas enters the air pump 22 in turn through the carbon canister 12, the first passage port 251 and the second passage port 252, and is discharged into the atmosphere through the air pump 22.

[0088] If the absolute value of the pressure value detected by the first pressure sensor 231 and the absolute value of the pressure value detected by the second pressure sensor 241 both increase, it is determined that the leak diagnosis device 20 and the isolation valve 13 are working normally. If the absolute value of the pressure value detected by the first pressure sensor 231 increases and the pressure value detected by the second pressure sensor 241 does not change, the second pressure sensor 241 or the isolation valve 13 is faulty, or the reversing control valve 25 fails to switch to the second state. If the absolute value of the pressure value detected by the second pressure sensor 241 increases and the pressure value detected by the first pressure sensor 231 does not change, the first pressure sensor 231 is faulty. If the pressure values detected by the first pressure sensor 231 and the second pressure sensor 241 both do not change, the first pressure sensor 231 is faulty, and the second pressure sensor 241 or the isolation valve 13 or the reversing control valve 25 is faulty.

[0089] In step 120, if the leak diagnosis device and the isolation valve are working normally, the third through hole is controlled to be not in communication with the atmosphere, the isolation valve is controlled to be closed, and the air pump is controlled to be in a working state, so that the air pump pumps air to or from the carbon canister through the third through hole.

[0090] In this step, the controller 21 controls the reversing control valve 25 to switch to the second state, so as to realize the communication between the second air port 222 and the third through hole 122 and the non-communication between the third through hole 122 and the atmosphere. Specifically, in the second state, the first passage port 251 of the reversing control valve 25 is in communication with the second passage port 252. When the air pump 22 pumps air to the carbon canister 12, the gas flowing out of the second air port 222 flows into the carbon canister 12 through the third through hole 122; when the air pump 22 pumps air from the carbon canister 12, the gas in the carbon canister 12 flows into the air pump 22 through the third through hole 122, and then flows to the atmosphere through the air pump 22.

[0091] In step 130, the pressure value of the carbon canister detected by the pressure sensor is collected, and it is determined whether the leakage of the carbon canister is greater than the maximum allowable leakage of the carbon canister according to the pressure value of the carbon canister detected by the pressure sensor.

[0092] In one embodiment, the step 130 of collecting the pressure value of the carbon canister detected by the pressure sensor and determining whether the leakage of the carbon canister is greater than the maximum allowable leakage of the carbon canister according to the pressure value of the carbon canister detected by the pressure sensor includes the following process:

[0093] First, when the pressure value of the carbon canister detected by the pressure sensor 23 stabilizes, the third pressure value of the carbon canister detected by the pressure sensor 23 is collected.

[0094] Subsequently, when the absolute value of the third pressure value is greater than or equal to a second pressure threshold, it is determined that the leakage amount of the carbon can 12 is less than or equal to the maximum allowable leakage amount of the carbon can 12; wherein the leakage amount of the carbon can 12 is the maximum allowable leakage amount of the carbon can 12, and the absolute value of the third pressure value is the second pressure threshold when the pressure value of the carbon can detected by the pressure sensor 23 reaches a stable state.

[0095] In this embodiment, the pressure value detected by the pressure sensor is a relative pressure. When the leakage diagnosis device further comprises a reference channel 26 and a reversing control valve 25, the leakage diagnosis method further comprises:

[0096] Controlling the reversing control valve to switch to the first state, and obtaining the fourth pressure value detected by the pressure sensor when the fourth pressure value between the position of the reference channel with the minimum flow area and the second gas port reaches a stable state; the ventilation amount of the reference channel is less than or equal to the maximum allowable leakage amount of the carbon can. The absolute value of the fourth pressure value is determined as the second pressure threshold.

[0097] The fourth pressure value when the pressure between the position of the reference channel 26 with the minimum flow area and the second gas port 222 reaches a stable state is determined as the second pressure threshold, that is, the second pressure threshold is tested each time, and the fourth pressure value may be affected by the geographical location and the environment. Therefore, compared with setting the second pressure threshold as a fixed value, the second pressure threshold measured in this embodiment is more accurate, and thus the accuracy of judging the leakage condition of the carbon can 12 under different pressure environments can be improved.

[0098] Further, before obtaining the fourth pressure value detected by the pressure sensor when the fourth pressure value between the position of the reference channel with the minimum flow area and the second gas port reaches a stable state, the leakage diagnosis method further comprises: if the absolute value of the fourth pressure value detected by the pressure sensor 23 is within a preset pressure range, it is determined that the reference channel 26 is not leaking or blocked, wherein the fourth pressure value is an absolute pressure. If the absolute value of the fourth pressure value detected by the pressure sensor 23 is greater than the preset pressure range, it can be determined that the reference channel 26 is blocked; if the absolute value of the fourth pressure value detected by the pressure sensor 23 is less than the preset pressure range, it can be determined that the reference channel 26 is leaking. Before determining the second pressure threshold, it is detected whether the reference channel is blocked, which can improve the accuracy of the obtained second pressure threshold, and thus improve the accuracy of judging the leakage condition of the carbon can 12.

[0099] In another embodiment, when the pressure value detected by the pressure sensor 23 is an absolute pressure, the process of determining the second pressure threshold is as follows:

[0100] Firstly, the switching control valve 25 is controlled to switch to the first state, and when the fifth pressure value between the minimum flow area position of the reference channel 26 and the second gas port 222 reaches stability, the fifth pressure value and the current atmospheric pressure value are obtained; the ventilation amount at the minimum flow area position of the reference channel 26 is less than or equal to the maximum allowable leakage amount of the carbon canister 12;

[0101] Subsequently, the absolute value of the difference between the fifth pressure value and the atmospheric pressure value is determined as the second pressure threshold value.

[0102] In this way, the influence of the atmospheric pressure at different times on the determined second pressure threshold value can be avoided, the second pressure threshold value is more accurate, and the accuracy of diagnosis is improved.

[0103] In one embodiment, the second pressure threshold value can be a pressure range. The absolute value of the difference between the third pressure value and the first atmospheric pressure value is greater than or equal to the second pressure threshold value, which means that the absolute value of the difference between the third pressure value and the first atmospheric pressure value is greater than or equal to the maximum value of the second pressure threshold value; the absolute value of the difference between the third pressure value and the first atmospheric pressure value is less than the second pressure threshold value, which means that the absolute value of the difference between the third pressure value and the first atmospheric pressure value is less than the minimum value of the second pressure threshold value.

[0104] In one embodiment, the second pressure threshold value can be a value stored in the controller 21 in advance.

[0105] In step 140, if the leakage amount of the carbon canister is less than or equal to the maximum allowable leakage amount of the carbon canister, the isolation valve is controlled to be opened, the gas pump continues to work, the pressure value of the fuel evaporation system detected by the pressure sensor is collected, and it is judged whether the leakage amount of the fuel evaporation system is greater than the maximum allowable leakage amount of the fuel evaporation system according to the pressure value of the fuel evaporation system detected by the pressure sensor.

[0106] In one embodiment, the step 140 of collecting the pressure value detected by the pressure sensor and judging whether the leakage amount of the fuel evaporation system is greater than the maximum allowable leakage amount of the fuel evaporation system according to the pressure value of the fuel evaporation system detected by the pressure sensor includes the following process:

[0107] Firstly, when the absolute value of the first pressure value of the fuel evaporation system collected by the pressure sensor 23 is a first pressure threshold value, the working time length of the gas pump 22 since the isolation valve is opened is obtained.

[0108] Subsequently, if the working time length of the air pump 22 after the isolation valve 13 is opened is less than or equal to a first time length threshold, it is determined that the leakage amount of the fuel evaporation system 10 is less than or equal to the maximum allowable leakage amount of the fuel evaporation system 10. The working time length of the air pump 22 after the isolation valve is opened is the first time length threshold when the absolute value of the first pressure value collected by the pressure sensor 23 is the first pressure threshold, and the leakage amount of the fuel evaporation system 10 is the maximum allowable leakage amount of the fuel evaporation system 10.

[0109] In this embodiment, the working time length of the air pump 22 is obtained, and the leakage condition of the fuel tank 11 is judged according to the working time length. The judgment process is relatively simple. The working time length of the air pump 22 refers to the time length experienced by the air pump 22 from when the isolation valve is opened to when the absolute value of the first pressure value is the first pressure threshold.

[0110] In this embodiment, step 140 further includes the following process: if the working time length of the air pump 22 after the isolation valve 13 is opened is greater than the first time length threshold, it is determined that the leakage amount of the fuel evaporation system 10 is greater than the maximum allowable leakage amount of the fuel evaporation system 10.

[0111] If the absolute value of the first pressure value is the first pressure threshold, and the working time length of the air pump 22 is less than the first time length threshold, it indicates that the pressure change speed of the fuel evaporation system 10 is relatively fast, and the leakage amount of the fuel evaporation system 10 is relatively small. If the absolute value of the first pressure value is the first pressure threshold, and the working time length of the air pump 22 is greater than or equal to the first time length threshold, it indicates that the pressure change speed of the fuel evaporation system 10 is relatively slow, and the leakage amount of the fuel evaporation system 10 is relatively large. Therefore, the leakage condition of the fuel evaporation system 10 can be judged according to the working time length of the air pump 22.

[0112] In one embodiment, in step 140, the first time length threshold corresponding to the air pump 22 in the air extraction working state and the first time length threshold corresponding to the air pump 22 in the air pumping working state can be the same or different.

[0113] In one embodiment, the first time length threshold can be a time length range. The working time length of the air pump 22 is less than the minimum value of the first time length threshold; the working time length of the air pump 22 is greater than or equal to the maximum value of the first time length threshold.

[0114] In one embodiment, the first time length threshold and the first pressure threshold can be values pre-stored in the controller.

[0115] In one embodiment, the first pressure threshold and the first time length threshold can be determined by the following process:

[0116] The fuel evaporation system with the same volume as the fuel evaporation system to be diagnosed is selected as the experimental fuel evaporation system, and the leakage of the experimental fuel evaporation system is set to the maximum allowable leakage. The air pump is used to pump or exhaust the experimental fuel evaporation system. After the air pump starts to work, the pressure value in the experimental fuel evaporation system is detected at multiple detection time points. The time length between each detection time point and the time point when the air pump starts to work is the working time length of the air pump. The detected pressure of the experimental fuel evaporation system is the relative pressure. One of the working time lengths can be selected as the first time length threshold, and the absolute value of the pressure value corresponding to the first time length threshold is the first pressure threshold.

[0117] Further, the air pump continues to pump or exhaust the experimental fuel evaporation system until the absolute value of the pressure value of the experimental fuel evaporation system reaches the maximum value, and at this time, the working time length of the air pump is the maximum working time length. The product of the absolute value of the maximum pressure value and a coefficient (the coefficient is greater than 0 and less than 1) can be selected as the first pressure threshold, and the product of the maximum working time length and the coefficient can be selected as the first time length threshold.

[0118] In another embodiment, the step 140 of collecting the pressure value detected by the pressure sensor and determining whether the leakage of the fuel evaporation system is greater than the maximum allowable leakage of the fuel evaporation system according to the pressure value of the fuel evaporation system detected by the pressure sensor includes the following process:

[0119] When the working time length of the air pump 22 after the isolation valve 13 is opened is the first time length threshold, the first pressure value of the fuel evaporation system detected by the pressure sensor 23 is collected.

[0120] If the absolute value of the first pressure value is less than the first pressure threshold, it is determined that the leakage of the fuel evaporation system 10 is greater than the maximum allowable leakage. When the leakage of the fuel evaporation system 10 is the maximum allowable leakage of the fuel evaporation system, and the absolute value of the first pressure value of the fuel evaporation system collected by the pressure sensor 23 is the first pressure threshold, the working time length of the air pump 22 after the isolation valve is opened is the first time length threshold.

[0121] In this embodiment, the first pressure value detected by the pressure sensor 23 when the working time length of the air pump 22 is the first time length threshold is obtained, and the leakage of the fuel tank 11 is determined according to the absolute value of the first pressure value. The determination process is relatively simple. The working time length of the air pump 22 refers to the time length experienced by the air pump 22 from the opening of the isolation valve 13 to the absolute value of the first pressure value being the first pressure threshold.

[0122] In this embodiment, step 140 further comprises the following process: if the absolute value of the first pressure value is greater than or equal to the first pressure threshold value, it is determined that the leakage amount of the fuel evaporation system 10 is less than or equal to the maximum allowable leakage amount.

[0123] If the working time of the air pump 22 after the isolation valve is opened is the first time threshold value, and the absolute value of the first pressure value is greater than or equal to the first pressure threshold value, it indicates that the pressure change speed of the fuel evaporation system 10 is relatively fast, and the leakage amount of the fuel evaporation system is relatively small. If the working time of the air pump 22 is the first time threshold value, and the absolute value of the first pressure value is less than the first pressure threshold value, it indicates that the pressure change speed of the fuel evaporation system 10 is relatively slow, and the leakage amount of the fuel evaporation system 10 is relatively large. Therefore, the leakage condition of the fuel evaporation system 10 can be determined according to the absolute value of the first pressure value.

[0124] In one embodiment, in step 140, the first time threshold value corresponding to the working state of the air pump 22 in the air extraction mode and the first time threshold value corresponding to the working state of the air pump 22 in the air pumping mode can be the same or different.

[0125] In one embodiment, the first pressure threshold value can be a pressure range. The absolute value of the first pressure value greater than or equal to the first pressure threshold value means that the absolute value of the first pressure value is greater than or equal to the maximum value of the first pressure threshold value. The absolute value of the first pressure value less than the first pressure threshold value means that the absolute value of the first pressure value is less than the minimum value of the first pressure threshold value.

[0126] In one embodiment, the first time threshold value and the first pressure threshold value can be values pre-stored in the controller.

[0127] In one embodiment, the first pressure threshold value and the first time threshold value can be determined by the following process:

[0128] An experimental fuel evaporation system with the same volume as the fuel evaporation system to be diagnosed is selected, and the leakage amount of the experimental fuel evaporation system is set to the maximum allowable leakage amount. The air pump is used to pump or extract air from the experimental fuel evaporation system. After the air pump starts to work, the pressure value in the experimental fuel evaporation system is detected at multiple detection time points. The time length between each detection time point and the time point when the air pump starts to work is the working time of the air pump. The detected pressure of the experimental fuel evaporation system is the relative pressure. One of the working time lengths can be selected as the first time threshold value, and the absolute value of the pressure value corresponding to the first time threshold value is the first pressure threshold value.

[0129] Further, the air pump continuously pumps or exhausts the experimental fuel evaporation system until the absolute value of the pressure value of the experimental fuel evaporation system reaches the maximum value, at which time the working time length of the air pump is the maximum working time length. Optionally, the product of the absolute value of the maximum pressure value and a coefficient (the coefficient is greater than 0 and less than 1) can be taken as the first pressure threshold value, and the product of the maximum working time length and the coefficient can be taken as the first time length threshold value.

[0130] Further, the pressure value detected by the pressure sensor 23 is collected, and whether the leakage amount of the fuel evaporation system 10 is greater than the maximum allowable leakage amount is determined according to the pressure value of the fuel evaporation system detected by the pressure sensor 23, and the method further comprises:

[0131] When the working time length of the air pump 22 after the isolation valve 13 is opened is the first time length threshold value, and the absolute value of the first pressure value is less than the first pressure threshold value, it is determined that the leakage amount of the fuel evaporation system 10 is greater than the maximum allowable leakage amount of the fuel evaporation system.

[0132] After the leakage amount of the fuel evaporation system 10 is determined to be greater than the maximum allowable leakage amount of the fuel evaporation system, the air pump 22 is controlled to continue to work, and when the working time length of the air pump 22 after the isolation valve 13 is opened reaches a second time length threshold value, the second pressure value of the fuel evaporation system detected by the pressure sensor 23 is collected; the second time length threshold value is greater than the first time length threshold value.

[0133] If the absolute value of the second pressure value is greater than or equal to the first pressure threshold value, it is determined that the leakage amount of the fuel evaporation system 10 is a low leakage amount; if the absolute value of the second pressure value is less than the first pressure threshold value, it is determined that the leakage amount of the fuel evaporation system 10 is a high leakage amount.

[0134] When the leakage amount of the fuel evaporation system 10 is greater than the maximum allowable leakage amount, the fuel evaporation system 10 is further detected to determine whether the leakage amount of the fuel evaporation system 10 is a low leakage amount or a high leakage amount, that is, the leakage amount of the fuel evaporation system 10 can be semi-quantified, and more accurate leakage diagnosis can be achieved, which is convenient for subsequent development of maintenance strategies for the fuel evaporation system 10.

[0135] In one embodiment, the second time length threshold value can be determined by the following process: selecting an oil tank with the same volume as the oil tank to be diagnosed as an experimental oil tank, and the leakage amount of the experimental oil tank is the minimum value of the high leakage amount. The air pump pumps or exhausts the experimental oil tank, detects the pressure value in the experimental oil tank, and the working time length of the air pump when the absolute value of the pressure value in the experimental oil tank is equal to the first pressure threshold value is the second time length threshold value.

[0136] In one embodiment, after the step 140 of collecting the pressure value detected by the pressure sensor and determining whether the leakage amount of the fuel evaporation system is greater than the maximum allowable leakage amount of the fuel evaporation system according to the pressure value of the fuel evaporation system detected by the pressure sensor, the leakage diagnosis method further comprises: controlling the isolation valve to open, and controlling the third through hole to be in communication with the atmosphere. When the leakage diagnosis device comprises the reversing control valve, the controller controls the reversing control valve to switch to the first state to realize the communication between the third through hole and the atmosphere.

[0137] After the step 140, the first through hole 111 of the fuel tank 11 is controlled to be in communication with the atmosphere, so that the pressure balance in the fuel tank 11 is realized, and the normal pressure in the fuel evaporation system 10 during the subsequent vehicle operation is ensured.

[0138] In one embodiment, during the steps 110 to 140, the leakage diagnosis method further comprises: if a diagnosis termination condition is detected, terminating the leakage diagnosis process. The diagnosis termination condition comprises: a control system failure, the number of leakage diagnosis processes in one single driving trip reaching a maximum threshold value, the pressure fluctuation detected by the pressure sensor exceeding a set value, the pressure value detected by the pressure sensor suddenly dropping to or rising to the atmospheric pressure (which may occur due to the opening of the fuel tank cover), the vehicle power voltage fluctuation exceeding a set value, no diagnosis being performed within a specified time period, the fuel tank pressure increasing speed exceeding a set value, etc.

[0139] In one embodiment, the vehicle in which the fuel evaporation system 10 is located further comprises a display screen electrically connected to the controller 21. After the step 140, the controller can send the diagnosis result to the display screen and control the display screen to display the diagnosis information. Alternatively, the controller is in communication connection with an external electronic device. After the step 140, the controller can send the diagnosis result to the electronic device.

[0140] The embodiments of the present application also provide a leakage diagnosis device. The leakage diagnosis device is used for a fuel evaporation system to diagnose whether the leakage amount of the fuel evaporation system is greater than the maximum allowable leakage amount thereof. The fuel evaporation system comprises a fuel tank, a carbon canister and an isolation valve, the fuel tank is provided with a first through hole, the carbon canister is provided with a second through hole and a third through hole, and the isolation valve is arranged between the first through hole and the second through hole. The leakage diagnosis device comprises a gas pump, a pressure sensor and a controller. The gas pump comprises a first gas port and a second gas port in communication with the atmosphere. The pressure sensor is used for detecting the gas pressure of the fuel evaporation system. The controller executes the leakage diagnosis method described in any one of the embodiments.

[0141] The leakage diagnosis device and the leakage diagnosis method provided by the embodiments of the present application belong to the same inventive concept, and the descriptions of related details and beneficial effects can be referred to each other, which will not be described here again.

[0142] The above descriptions are only the preferred embodiments of the present application, not intended to limit the present application in any form. Although the present application has been disclosed as the preferred embodiments, it is not intended to limit the present application. Any person skilled in the art can make some changes or modifications to the above disclosed technical contents without departing from the scope of the present application, and make equivalent embodiments with equivalent changes. Any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present application shall still fall within the scope of the present application.

[0143] This patent document contains material subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it exists in the official records and files of the Patent and Trademark Office.

Claims

1. A method of diagnosing a leak in a fuel vapor system, comprising: The fuel evaporation system comprises a fuel tank, a carbon canister and an isolation valve, the fuel tank is provided with a first through hole, the carbon canister is provided with a second through hole and a third through hole, and the isolation valve is arranged between the first through hole and the second through hole; the leakage diagnosis method is applied to a controller of a leakage diagnosis device, the leakage diagnosis device further comprises a gas pump and a pressure sensor; the gas pump comprises a first gas port and a second gas port which are in communication with the atmosphere; the pressure sensor is used for detecting the gas pressure of the fuel evaporation system; the leakage diagnosis method comprises: detecting whether the leakage diagnosis device and the isolation valve are normally working; if the leakage diagnosis device and the isolation valve are normally working, controlling the third through hole to be not in communication with the atmosphere, controlling the isolation valve to be closed, and controlling the gas pump to be in a working state, so that the gas pump pumps or exhausts gas to or from the carbon canister through the third through hole; collecting the pressure value of the carbon canister detected by the pressure sensor, and judging whether the leakage amount of the carbon canister is greater than the maximum allowable leakage amount of the carbon canister according to the pressure value of the carbon canister detected by the pressure sensor; if the leakage amount of the carbon canister is less than or equal to the maximum allowable leakage amount of the carbon canister, controlling the isolation valve to be opened, controlling the gas pump to continue working, collecting the pressure value of the fuel evaporation system detected by the pressure sensor, and judging whether the leakage amount of the fuel evaporation system is greater than the maximum allowable leakage amount of the fuel evaporation system according to the pressure value of the fuel evaporation system detected by the pressure sensor.

2. The method of diagnosing a leak of a fuel vapor system according to claim 1, wherein The collection of the pressure value detected by the pressure sensor and the judgment of whether the leakage amount of the fuel evaporation system is greater than the maximum allowable leakage amount of the fuel evaporation system according to the pressure value of the fuel evaporation system detected by the pressure sensor comprises: when the absolute value of the first pressure value of the fuel evaporation system collected by the pressure sensor is a first pressure threshold value, obtaining the working time length of the gas pump after the isolation valve is opened; if the working time length of the gas pump after the isolation valve is opened is less than or equal to a first time threshold value, it is determined that the leakage amount of the fuel evaporation system is less than or equal to the maximum allowable leakage amount of the fuel evaporation system; wherein the leakage amount of the fuel evaporation system is the maximum allowable leakage amount of the fuel evaporation system, and when the absolute value of the first pressure value of the fuel evaporation system collected by the pressure sensor is the first pressure threshold value, the working time length of the gas pump after the isolation valve is opened is the first time threshold value; or The collection of the pressure value detected by the pressure sensor and the judgment of whether the leakage amount of the fuel evaporation system is greater than the maximum allowable leakage amount of the fuel evaporation system according to the pressure value of the fuel evaporation system detected by the pressure sensor comprises: when the working time length of the gas pump after the isolation valve is opened is a first time threshold value, collecting the first pressure value of the fuel evaporation system detected by the pressure sensor; If the absolute value of the first pressure value is less than the first pressure threshold, it is determined that the leakage amount of the fuel evaporation system is greater than the maximum allowable leakage amount; wherein the leakage amount of the fuel evaporation system is the maximum allowable leakage amount of the fuel evaporation system, and when the absolute value of the first pressure value collected by the pressure sensor of the fuel evaporation system is the first pressure threshold, the working time of the gas pump after the isolation valve is opened is the first time threshold.

3. The method of diagnosing a leak of a fuel vapor system according to claim 2, wherein When the working time of the gas pump after the isolation valve is opened is the first time threshold, the absolute value of the first pressure value is less than the first pressure threshold, and after it is determined that the leakage amount of the fuel evaporation system is greater than the maximum allowable leakage amount of the fuel evaporation system, the pressure value detected by the pressure sensor is collected, and it is determined whether the leakage amount of the fuel evaporation system is greater than the maximum allowable leakage amount of the fuel evaporation system according to the pressure value of the fuel evaporation system detected by the pressure sensor, further comprising: controlling the gas pump to continue to work, and collecting a second pressure value of the fuel evaporation system detected by the pressure sensor when the working time of the gas pump after the isolation valve is opened reaches a second time threshold; 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, it is determined that the leakage amount of the fuel evaporation system is a low leakage amount; if the absolute value of the second pressure value is less than the first pressure threshold, it is determined that the leakage amount of the fuel evaporation system is a high leakage amount.

4. The method of diagnosing a leak of a fuel vapor system according to claim 1, wherein The collection of the pressure value of the carbon tank detected by the pressure sensor, and the determination of whether the leakage amount of the carbon tank is greater than the maximum allowable leakage amount of the carbon tank according to the pressure value of the carbon tank detected by the pressure sensor, comprises: collecting a third pressure value of the carbon tank detected by the pressure sensor when the pressure value of the carbon tank detected by the pressure sensor reaches a stable state; If the absolute value of the third pressure value is greater than or equal to a second pressure threshold, it is determined that the leakage amount of the carbon tank is less than or equal to the maximum allowable leakage amount of the carbon tank; wherein the leakage amount of the carbon tank is the maximum allowable leakage amount of the carbon tank, and when the pressure value of the carbon tank detected by the pressure sensor reaches a stable state, the absolute value of the third pressure value is the second pressure threshold.

5. The method of diagnosing a leak of a fuel vapor system according to claim 4, wherein The leakage diagnosis device further comprises a reference channel and a reversing control valve, the reversing control valve is arranged between the second gas port and the third through hole; the reversing control valve comprises a first channel port, a second channel port and a third channel port, the first channel port communicates with the third through hole, the second channel port communicates with the second gas port, and the third channel port communicates with the atmosphere; the reversing control valve has a first state and a second state, the first channel port communicates with the third channel port when the reversing control valve is in the first state, and the first channel port communicates with the second channel port when the reversing control valve is in the second state; one end of the reference channel communicates with the second gas port, and the other end communicates with the third through hole; The leakage diagnosis method further comprises: Controlling the reversing control valve to switch to the first state, when a fourth pressure value between the minimum flow area position of the reference channel and the second gas port reaches stability, the fourth pressure value is obtained; the ventilation amount at the minimum flow area position of the reference channel is less than or equal to the maximum allowable leakage amount of the carbon canister; The absolute value of the fourth pressure value is determined as the second pressure threshold value.

6. The method of diagnosing a leak of a fuel vapor system according to claim 5, wherein The inner diameter of the minimum flow area position of the reference channel ranges from 0.3 mm to 1.0 mm.

7. The method of diagnosing a leak of a fuel vapor system according to claim 1, wherein The detection of whether the leakage diagnosis device and the isolation valve are working normally includes: Controlling the air pump to work, detecting the current of the air pump, and if the current of the air pump rises, judging that the air pump is working normally; Controlling the carbon canister to be disconnected with the atmosphere, controlling the air pump to continue working, controlling the isolation valve to open, and collecting the pressure value detected by the pressure sensor, and if the absolute value of the pressure value detected by the pressure sensor rises, determining that the isolation valve and the pressure sensor are working normally.

8. The method of diagnosing a leak of a fuel vapor system according to claim 1, wherein The leakage diagnosis device further includes a reversing control valve, which is arranged between the second gas port and the third through hole; the reversing control valve includes a first channel port, a second channel port and a third channel port, the first channel port is communicated with the third through hole, the second channel port is communicated with the second gas port, and the third channel port is communicated with the atmosphere; the reversing control valve has a first state and a second state, when the reversing control valve is in the first state, the first channel port is communicated with the third channel port, and when the reversing control valve is in the second state, the first channel port is communicated with the second channel port; The control of the third through hole to be disconnected with the atmosphere includes: controlling the reversing control valve to switch to the second state; and the air pump pumps air to or from the carbon canister through the second channel port, the first channel port and the third through hole in sequence.

9. The method of diagnosing a leak of a fuel vapor system according to claim 1, wherein After the collection of the pressure value of the fuel evaporation system detected by the pressure sensor and the judgment of whether the leakage amount of the fuel evaporation system is greater than the maximum allowable leakage amount of the fuel evaporation system according to the pressure value of the fuel evaporation system detected by the pressure sensor, the leakage diagnosis method further includes: Controlling the isolation valve to open and controlling the third through hole to be communicated with the atmosphere.

10. A leakage diagnosing apparatus characterized by comprising: The leakage diagnosis device is used for a fuel evaporation system; the fuel evaporation system includes an oil tank, a carbon canister and an isolation valve, the oil tank is provided with a first through hole, the carbon canister is provided with a second through hole and a third through hole, and the isolation valve is arranged between the first through hole and the second through hole; the leakage diagnosis device includes an air pump, a pressure sensor and a controller; the air pump includes a first gas port and a second gas port communicated with the atmosphere; the pressure sensor is used for detecting the gas pressure of the fuel evaporation system; The controller executes the leakage diagnosis method in any one of claims 1 to 9.

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