Diagnostic method and device for desorption flow of carbon canister, storage medium and vehicle

Abstract

The invention relates to the technical field of vehicles, and particularly discloses a carbon canister desorption flow diagnosis method and device, a storage medium and a vehicle, a carbon canister is arranged between an oil tank and an engine, and a carbon canister electromagnetic valve is arranged between the carbon canister and the engine. After the carbon canister electromagnetic valve is controlled to be opened for a first preset duration, first reference data of the engine are obtained, then the carbon canister electromagnetic valve is controlled to be closed for a second preset duration, and second reference data of the engine are obtained; determining an intake air mass flow difference value and a short-term fuel correction value difference value of the engine based on the first reference data and the second reference data; the carbon canister desorption flow is diagnosed according to the inlet air mass flow difference value and the short-term fuel correction value difference value, so that the diagnosis process of the carbon canister desorption flow can be simplified, the diagnosis cost and influence parameters are reduced, and the diagnosis coverage rate, accuracy and robustness are improved.

Description

Technical Field

[0001] This invention relates to the field of vehicle technology, and in particular to a diagnostic method and apparatus for carbon canister desorption flow rate, a storage medium, and a vehicle. Background Technology

[0002] With increasingly stringent environmental regulations, countries worldwide require vehicles to be equipped with OBD (On-Board Diagnostics) systems to monitor the operational status of critical emission components. In modern automotive engine management systems, to prevent fuel vapors from being directly released into the atmosphere and causing environmental pollution, activated carbon canisters (referred to as "carbon canisters") are commonly used to adsorb fuel vapors volatilized from the fuel tank. When the engine is under appropriate operating conditions, the fuel vapors adsorbed in the carbon canister are introduced into the intake manifold through a vacuum effect to participate in combustion; this process is called "desorption."

[0003] To ensure the proper functioning of the EVAP (Evaporative Fuel Activated Power Control) system, the China VI emission standard requires the ability to diagnose desorption flow to detect issues such as leaks, blockages, or malfunctions in the charcoal canister solenoid valve. Diagnostic methods include using differential pressure sensors to detect the charcoal canister's electromagnetic flow and employing estimation models; however, these methods are costly and offer relatively low diagnostic accuracy. Summary of the Invention

[0004] This invention aims to at least partially solve one of the technical problems in the related art. Therefore, the first objective of this invention is to provide a diagnostic method for the desorption flow rate of a carbon canister, which simplifies the diagnostic process, reduces diagnostic costs and influencing parameters, and improves diagnostic coverage, accuracy, and robustness.

[0005] A second objective of this invention is to provide a computer-readable storage medium.

[0006] The third objective of this invention is to provide a diagnostic device for the desorption flow rate of a carbon canister.

[0007] The fourth objective of this invention is to provide a vehicle.

[0008] To achieve the above objectives, the present invention proposes a diagnostic method for charcoal canister desorption flow rate. The charcoal canister is disposed between the fuel tank and the engine, and a charcoal canister solenoid valve is disposed between the charcoal canister and the engine. The method includes: when the engine meets the diagnostic enable conditions, controlling the charcoal canister solenoid valve to open for a first preset duration, acquiring first reference data of the engine, then controlling the charcoal canister solenoid valve to close for a second preset duration, and acquiring second reference data of the engine; determining the intake air mass flow rate difference and short-term fuel trim difference of the engine based on the first reference data and the second reference data; and diagnosing the charcoal canister desorption flow rate based on the intake air mass flow rate difference and the short-term fuel trim difference.

[0009] In this embodiment of the invention, the charcoal canister is disposed between the fuel tank and the engine, and a charcoal canister solenoid valve is also disposed between the charcoal canister and the engine. In the diagnostic method for charcoal canister desorption flow, it is first determined whether the engine meets the diagnostic enable conditions. If it does, the charcoal canister solenoid valve is controlled to open for a first preset duration, and the first reference data of the engine is acquired. Then, the charcoal canister solenoid valve is closed for a second preset duration, and the second reference data of the engine is acquired again. The difference between the first reference data and the second reference data can be used to determine the difference between the intake air mass flow rate and the short-term fuel correction value of the engine. Based on these two differences, the charcoal canister desorption flow can be diagnosed, thereby simplifying the diagnostic process for charcoal canister desorption flow, reducing diagnostic costs and influencing parameters, and improving diagnostic coverage, accuracy and robustness.

[0010] In some embodiments of the present invention, the desorption flow rate of the charcoal canister is diagnosed based on the difference between the intake air mass flow rate and the difference between the short-term fuel correction value, including: when the difference between the intake air mass flow rate and the short-term fuel correction value is less than or equal to a first preset difference and the difference between the short-term fuel correction value and the second preset difference, it is determined that the charcoal canister has no desorption flow rate; when the difference between the intake air mass flow rate and the short-term fuel correction value is greater than the first preset difference and the difference between the short-term fuel correction value and the second preset difference, it is determined that the charcoal canister is in normal use.

[0011] In some embodiments of the present invention, both the first preset difference and the second preset difference are determined when the carbon canister is in a state of no desorption flow.

[0012] In some embodiments of the present invention, the method further includes: after completing the diagnosis of the desorption flow rate of the carbon canister, storing and uploading the diagnosis result of the desorption flow rate of the carbon canister.

[0013] In some embodiments of the present invention, the diagnostic enabling conditions include: the engine is in closed-loop control mode, the engine coolant temperature is greater than a preset temperature, the engine speed is within a preset speed range, the throttle opening change rate of the engine is lower than a preset change rate, the canister solenoid valve is open and within a preset opening range, the engine EGR is closed, and the engine air flow sensor is in normal condition and the diagnostic time since the last canister desorption flow rate diagnosis has reached a third preset time.

[0014] In some embodiments of the present invention, both the first reference data and the second reference data include the actual intake mass flow rate of the engine, the engine speed, the intake manifold absolute pressure of the engine, the throttle opening of the engine, the short-term fuel trim of the engine, and the duty cycle of the canister solenoid valve.

[0015] In some embodiments of the present invention, the second preset duration is less than the first preset duration.

[0016] To achieve the above objectives, a second aspect of the present invention provides a computer-readable storage medium storing a diagnostic program for the desorption flow rate of a carbon canister, wherein when the diagnostic program is executed by a processor, the method for diagnosing the desorption flow rate of a carbon canister as described in any of the above embodiments is implemented.

[0017] The computer-readable storage medium of this invention executes a diagnostic program for carbon canister desorption flow stored thereon via a processor, which simplifies the diagnostic process for carbon canister desorption flow, reduces diagnostic costs and influencing parameters, and improves diagnostic coverage, accuracy, and robustness.

[0018] To achieve the above objectives, a third aspect of the present invention provides a diagnostic device for charcoal canister desorption flow rate. The charcoal canister is disposed between the fuel tank and the engine, and a charcoal canister solenoid valve is disposed between the charcoal canister and the engine. The device includes: a control module, configured to, when the engine meets diagnostic enable conditions, control the charcoal canister solenoid valve to open for a first preset duration, acquire first reference data of the engine, and then control the charcoal canister solenoid valve to close for a second preset duration, and acquire second reference data of the engine; a determination module, configured to determine the intake air mass flow rate difference and the short-term fuel trim difference of the engine based on the first reference data and the second reference data; and a diagnostic module, configured to diagnose the charcoal canister desorption flow rate based on the intake air mass flow rate difference and the short-term fuel trim difference.

[0019] In this embodiment of the invention, the charcoal canister is disposed between the fuel tank and the engine, and a charcoal canister solenoid valve is also disposed between the charcoal canister and the engine. The diagnostic device for charcoal canister desorption flow includes a control module, a determination module, and a diagnostic module. First, the control module determines whether the engine meets the diagnostic enable conditions. If it does, it controls the charcoal canister solenoid valve to open for a first preset duration and acquires the first reference data of the engine. Then, it closes the charcoal canister solenoid valve for a second preset duration and acquires the second reference data of the engine. The determination module can determine the difference between the engine's intake air mass flow rate and the difference between the short-term fuel correction value through the first and second reference data. The diagnostic module can diagnose the charcoal canister desorption flow based on these two differences, thereby simplifying the diagnostic process for charcoal canister desorption flow, reducing diagnostic costs and influencing parameters, and improving diagnostic coverage, accuracy, and robustness.

[0020] To achieve the above objectives, a fourth aspect of the present invention provides a vehicle comprising a carbon canister and a diagnostic device for carbon canister desorption flow rate as described in the above embodiments, the diagnostic device being used to diagnose the desorption flow rate of the carbon canister.

[0021] The vehicle in this embodiment of the invention, through the diagnostic device for charcoal canister desorption flow described above, can simplify the diagnostic process for charcoal canister desorption flow, reduce diagnostic costs and influencing parameters, and improve diagnostic coverage, accuracy, and robustness.

[0022] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the connection of the charcoal canister in one embodiment of the present invention; Figure 2 This is a flowchart of a method for diagnosing the desorption flow rate of a carbon canister in one embodiment of the present invention; Figure 3 This is a block diagram of the diagnostic device for carbon canister desorption flow rate in an embodiment of the present invention; Figure 4 This is a vehicle block diagram according to an embodiment of the present invention. Detailed Implementation

[0024] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0025] The following describes, with reference to the accompanying drawings, a method and apparatus for diagnosing the desorption flow rate of the carbon canister, a storage medium, and a vehicle according to embodiments of the present invention.

[0026] Figure 1 This is a schematic diagram of the connection of the charcoal canister in one embodiment of the present invention.

[0027] like Figure 1 As shown, the charcoal canister is positioned between the fuel tank and the engine, and a charcoal canister solenoid valve is also installed between the charcoal canister and the engine. Fuel vapor from the fuel tank, after passing through the charcoal canister, can be supplied to the engine through the charcoal canister solenoid valve. Fresh air can be supplied to the engine through the hot film mass air flow sensor (HFM), while the catalytic converter can treat and expel the exhaust gases produced by the engine.

[0028] Figure 2 This is a flowchart of a method for diagnosing the desorption flow rate of a carbon canister in one embodiment of the present invention.

[0029] like Figure 2 As shown, the method for diagnosing the desorption flow rate of the carbon canister according to an embodiment of the present invention includes the following steps: S10: When the engine meets the diagnostic enable conditions, after controlling the charcoal canister solenoid valve to open for a first preset time, the engine's first reference data is acquired. Then, the charcoal canister solenoid valve is controlled to close for a second preset time, and the engine's second reference data is acquired.

[0030] S20, based on the first reference data and the second reference data, determines the difference in the engine's intake air mass flow rate and the difference in the short-term fuel correction value.

[0031] S30 diagnoses the charcoal canister desorption flow rate based on the difference between the intake air mass flow rate and the short-term fuel correction value.

[0032] Specifically, the engine diagnostic enabling conditions may include: the engine is in closed-loop control mode, the engine coolant temperature is higher than a preset temperature, the engine speed is within a preset speed range, the throttle opening change rate is lower than a preset change rate, the charcoal canister solenoid valve is open and within a preset opening range, the engine EGR valve is closed, and the engine air flow sensor is in normal condition and the time elapsed since the last charcoal canister desorption flow rate diagnosis has reached a third preset time. In one specific embodiment, the preset temperature may be 60 degrees Celsius, the preset speed range may be 1500-3000 rpm, the preset change rate can be used to indicate whether the operating condition is stable and can be determined according to the specific operating conditions, the preset opening range may be 30%-80%, and the purpose of setting the third preset time is to avoid interference from frequent diagnostics; optionally, the third preset time may be 1 minute, etc.

[0033] Once the engine meets the diagnostic enable conditions, the charcoal canister solenoid valve can be opened for a first preset duration. Then, the engine's first baseline data is acquired. Next, the charcoal canister solenoid valve is closed for a second preset duration, and the engine's second baseline data is acquired. The second preset duration is shorter than the first preset duration; for example, the first preset duration could be more than 5 seconds, such as 6-10 seconds, while the second preset duration could be 2-5 seconds. It should be noted that during the two baseline data acquisitions, only the state of the charcoal canister solenoid valve is controlled; other operating conditions remain unchanged.

[0034] Based on the first and second reference data, the difference in intake air mass flow rate before and after the charcoal canister solenoid valve is closed can be determined. Since desorbed gas replaces some fresh air, the actual air mass flow rate measured when the charcoal canister solenoid valve is open will be less than the air mass flow rate when it is closed. Based on the first and second reference data, the difference in short-term fuel trim value before and after the charcoal canister solenoid valve is closed can also be determined, which can be calculated using a preset formula. It should be noted that both the first and second reference data include the engine's actual intake air mass flow rate, engine speed, engine intake manifold absolute pressure, engine throttle opening, engine short-term fuel trim value, and charcoal canister solenoid valve duty cycle.

[0035] Once the intake air mass flow rate difference and the short-term fuel trim difference are determined, the state of the charcoal canister can be determined by judging the intake air mass flow rate difference and the short-term fuel trim difference, that is, judging whether the charcoal canister has desorption flow.

[0036] In this embodiment, the charcoal canister desorption flow rate is diagnosed based on the difference between the intake air mass flow rate and the difference between the short-term fuel correction value, including: When the difference in intake air mass flow rate is less than or equal to the first preset difference and the difference in short-term fuel correction value is less than or equal to the second preset difference, it is determined that there is no desorption flow in the charcoal canister. When the difference in intake air mass flow rate is greater than the first preset difference and the difference in short-term fuel correction value is greater than the second preset difference, the charcoal canister is determined to be in normal use.

[0037] Specifically, both the first and second preset differences are determined through prior experiments. When the intake air mass flow rate difference is less than or equal to the first preset difference, and the short-term fuel correction value difference is greater than the second preset difference, it can be determined that the charcoal canister has no desorption flow, indicating that the pipeline may be blocked or the valve may be stuck. Conversely, when the intake air mass flow rate difference is greater than the first preset difference and the short-term fuel correction value difference is greater than the second preset difference, it can be determined that the charcoal canister is in normal operating condition, and there is no blockage or valve sticking. Both the first and second preset differences are determined when the charcoal canister is in a state of no desorption flow. After completing the diagnosis of the charcoal canister desorption flow rate, the diagnostic results are stored and uploaded. Furthermore, if necessary, the vehicle control unit can also illuminate the power fault light when there is no charcoal canister desorption flow rate and generate corresponding fault codes. For example, fault code P044100 indicates abnormal flow rate in the low-load desorption line, which is prone to occur when the turbocharger is not working, while fault code P115A00 indicates abnormal flow rate in the high-load desorption line, which is prone to occur when the turbocharger is working.

[0038] In a specific embodiment, the following describes the implementation process of the present invention using a 2.0L turbocharged gasoline engine as an example: First, the vehicle controller monitors the engine operating status in real time. When the vehicle is driving at a constant speed on urban roads (specific engine conditions could be 2000 rpm, 50% load, and coolant temperature 80℃) and the charcoal canister solenoid valve is open with an 80% duty cycle, all diagnostic enabling conditions are met. At this time, parameters such as the current actual intake air mass flow rate M, intake manifold absolute pressure MAP, and short-term fuel trim value STFT are automatically collected. After filtering, the intake air mass flow rate M = 6.2 g / s, and the short-term fuel trim value STFT = -2.5%. Then, the charcoal canister solenoid valve is closed for 3 seconds, and the intake air mass flow rate M rises to 6.35 g / s, and the short-term fuel trim value STFT becomes +1.8%. After reopening, the parameters return to their original levels. Calculations show ΔM = 6.35 - 6.2 = 0.15 g / s, ΔFR = (+1.8%) - (-2.5%) = 4.3%, which is considered normal. If the desorption pipeline is blocked by human intervention, and no desorption flow occurs, and the measured ΔM = 0.01 < 0.05 g / s and ΔFR = 0.1% < 0.5%, with no significant change, then fault P0441 will be reported.

[0039] In summary, the diagnostic method for carbon canister desorption flow rate in this embodiment of the invention can simplify the diagnostic process, reduce diagnostic costs and influencing parameters, and improve diagnostic coverage, accuracy and robustness.

[0040] Furthermore, the present invention proposes a computer-readable storage medium storing a diagnostic program for the desorption flow rate of the carbon canister. When the diagnostic program is executed by a processor, it implements the diagnostic method for the desorption flow rate of the carbon canister as described in any of the above embodiments.

[0041] The computer-readable storage medium of this invention executes a diagnostic program for carbon canister desorption flow stored thereon via a processor, which simplifies the diagnostic process for carbon canister desorption flow, reduces diagnostic costs and influencing parameters, and improves diagnostic coverage, accuracy, and robustness.

[0042] Figure 3 This is a block diagram of the diagnostic device for carbon canister desorption flow rate in an embodiment of the present invention.

[0043] Furthermore, such as Figure 3 As shown, this invention proposes a diagnostic device 300 for the desorption flow rate of a carbon canister, wherein, as... Figure 1 As shown, the charcoal canister is located between the fuel tank and the engine, and a charcoal canister solenoid valve is installed between the charcoal canister and the engine. The diagnostic device 300 includes: a control module 301, a determination module 302, and a diagnostic module 303.

[0044] The control module 301 is used to control the charcoal canister solenoid valve to open for a first preset time when the engine meets the diagnostic enable conditions, acquire the first reference data of the engine, and then control the charcoal canister solenoid valve to close for a second preset time and acquire the second reference data of the engine; the determination module 302 is used to determine the difference between the intake air mass flow rate and the short-term fuel trim value based on the first reference data and the second reference data; the diagnostic module 303 is used to diagnose the charcoal canister desorption flow rate based on the difference between the intake air mass flow rate and the short-term fuel trim value.

[0045] In some embodiments of the present invention, the determining module 302 is further configured to: determine that the charcoal canister has no desorption flow when the intake air mass flow rate difference is less than or equal to a first preset difference and the short-term fuel correction value difference is less than or equal to a second preset difference; and determine that the charcoal canister is in normal use when the intake air mass flow rate difference is greater than the first preset difference and the short-term fuel correction value difference is greater than the second preset difference.

[0046] In some embodiments of the present invention, both the first preset difference and the second preset difference are determined when the carbon canister is in a state of no desorption flow.

[0047] In some embodiments of the present invention, the control module 301 is further configured to: after completing the diagnosis of the desorption flow rate of the carbon canister, store and upload the diagnosis result of the desorption flow rate of the carbon canister.

[0048] In some embodiments of the present invention, the diagnostic enabling conditions include: the engine is in closed-loop control mode, the engine coolant temperature is greater than a preset temperature, the engine speed is within a preset speed range, the throttle opening change rate of the engine is lower than a preset change rate, the charcoal canister solenoid valve is open and within a preset opening range, the engine EGR is closed, and the engine air flow sensor is in normal condition and the diagnostic time since the last charcoal canister desorption flow rate diagnosis has reached a third preset time.

[0049] In some embodiments of the present invention, both the first reference data and the second reference data include the engine's actual intake air mass flow rate, engine speed, engine intake manifold absolute pressure, engine throttle opening, engine short-term fuel trim amount, and the duty cycle of the canister solenoid valve.

[0050] In some embodiments of the present invention, the second preset duration is less than the first preset duration.

[0051] It should be noted that the specific implementation of the diagnostic device for the desorption flow rate of the carbon canister in the embodiments of the present invention can refer to the specific implementation of the diagnostic method for the desorption flow rate of the carbon canister in the above embodiments. To avoid redundancy, it will not be described again here.

[0052] In summary, the diagnostic device for carbon canister desorption flow rate in the embodiments of the present invention can simplify the diagnostic process for carbon canister desorption flow rate, reduce diagnostic costs and influencing parameters, and improve diagnostic coverage, accuracy and robustness.

[0053] Figure 4 This is a vehicle block diagram according to an embodiment of the present invention.

[0054] Furthermore, such as Figure 4 As shown, the present invention proposes a vehicle 400, which includes a carbon canister 401 and a carbon canister desorption flow diagnostic device 300 in the above embodiment. The carbon canister desorption flow diagnostic device 300 is used to diagnose the desorption flow of the carbon canister 401.

[0055] The vehicle in this embodiment of the invention, through the diagnostic device for charcoal canister desorption flow described above, can simplify the diagnostic process for charcoal canister desorption flow, reduce diagnostic costs and influencing parameters, and improve diagnostic coverage, accuracy, and robustness.

[0056] Furthermore, other components and functions of the vehicle in the embodiments of the present invention are known to those skilled in the art, and will not be described in detail here to reduce redundancy.

[0057] It should be noted that the logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be specifically implemented in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (such as a computer-based system, a processor-included system, or other system that can fetch and execute instructions from, an instruction execution system, apparatus, or device). For the purposes of this specification, "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transmit programs for use by, or in conjunction with, an instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of computer-readable media include: an electrical connection having one or more wires (electronic device), a portable computer disk drive (magnetic device), random access memory (RAM), read-only memory (ROM), erasable and editable read-only memory (EPROM or flash memory), fiber optic devices, and portable optical disc read-only memory (CDROM). Alternatively, the computer-readable medium may be paper or other suitable media on which the program can be printed, since the program can be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, interpreting, or otherwise processing as necessary, and then stored in a computer memory.

[0058] It should be understood that various parts of the present invention can be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0059] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0060] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0061] Furthermore, the terms "first," "second," etc., used in the embodiments of this invention are for descriptive purposes only and should not be construed as indicating or implying relative importance, or implicitly specifying the number of technical features indicated in this embodiment. Therefore, features defined with terms such as "first" and "second" in the embodiments of this invention can explicitly or implicitly indicate that the embodiment includes at least one of those features. In the description of this invention, the word "multiple" means at least two or more, such as two, three, four, etc., unless otherwise explicitly specified in the embodiments.

[0062] In this invention, unless otherwise explicitly specified or limited in the embodiments, the terms "installation," "connection," "joining," and "fixing" appearing in the embodiments should be interpreted broadly. For example, a connection can be a fixed connection, a detachable connection, or an integral part; it can also be a mechanical connection, an electrical connection, etc. Of course, it can also be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two components, or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific implementation.

[0063] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0064] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for diagnosing the desorption flow rate of a carbon canister, characterized in that, The charcoal canister is disposed between the fuel tank and the engine, and a charcoal canister solenoid valve is disposed between the charcoal canister and the engine. The method includes: When the engine meets the diagnostic enable conditions, the first reference data of the engine is acquired after the canister solenoid valve is opened for a first preset time. Then, the canister solenoid valve is closed for a second preset time and the second reference data of the engine is acquired. The intake air mass flow rate difference and short-term fuel correction value difference of the engine are determined based on the first reference data and the second reference data. The desorption flow rate of the charcoal canister is diagnosed based on the difference between the intake air mass flow rate and the difference between the short-term fuel correction value.

2. The diagnostic method for the desorption flow rate of the carbon canister according to claim 1, characterized in that, The desorption flow rate of the charcoal canister is diagnosed based on the difference between the intake air mass flow rate and the difference between the short-term fuel correction value, including: When the difference in intake air mass flow rate is less than or equal to a first preset difference and the difference in short-term fuel correction value is less than or equal to a second preset difference, it is determined that the charcoal canister has no desorption flow rate. When the difference in intake air mass flow rate is greater than a first preset difference and the difference in short-term fuel correction value is greater than a second preset difference, the charcoal canister is determined to be in normal use.

3. The diagnostic method for the desorption flow rate of the carbon canister according to claim 2, characterized in that, Both the first preset difference and the second preset difference are determined when the carbon canister is in a state of no desorption flow.

4. The diagnostic method for the desorption flow rate of the carbon canister according to claim 2, characterized in that, The method further includes: After completing the diagnosis of the desorption flow rate of the carbon canister, the diagnosis results of the carbon canister desorption flow rate are stored and uploaded.

5. The method for diagnosing the desorption flow rate of the carbon canister according to claim 1, characterized in that, The diagnostic enabling conditions include: the engine is in closed-loop control mode, the engine coolant temperature is greater than a preset temperature, the engine speed is within a preset speed range, the throttle opening change rate is lower than a preset change rate, the canister solenoid valve is open and within a preset opening range, the engine EGR is closed, and the engine air flow sensor is in normal condition and the diagnostic time since the last canister desorption flow rate diagnosis has reached a third preset time.

6. The method for diagnosing the desorption flow rate of the carbon canister according to claim 1, characterized in that, Both the first and second reference data include the engine's actual intake mass flow rate, the engine's rotational speed, the engine's intake manifold absolute pressure, the engine's throttle opening, the engine's short-term fuel trim, and the canister solenoid valve's duty cycle.

7. The method for diagnosing the desorption flow rate of the carbon canister according to any one of claims 1-6, characterized in that, The second preset duration is less than the first preset duration.

8. A computer-readable storage medium, characterized in that, It stores a diagnostic program for the desorption flow rate of the carbon canister, which, when executed by the processor, implements the diagnostic method for the desorption flow rate of the carbon canister as described in any one of claims 1-7.

9. A diagnostic device for the desorption flow rate of a carbon canister, characterized in that, The charcoal canister is disposed between the fuel tank and the engine, and a charcoal canister solenoid valve is disposed between the charcoal canister and the engine. The device includes: The control module is used to control the canister solenoid valve to open for a first preset time when the engine meets the diagnostic enable conditions, acquire the first reference data of the engine, and then control the canister solenoid valve to close for a second preset time and acquire the second reference data of the engine. The determination module is used to determine the intake air mass flow rate difference and short-term fuel correction value difference of the engine based on the first reference data and the second reference data; The diagnostic module is used to diagnose the charcoal canister desorption flow rate based on the difference between the intake air mass flow rate and the difference between the short-term fuel correction value.

10. A vehicle comprising a carbon canister and a diagnostic device for carbon canister desorption flow rate as described in claim 9, the diagnostic device being used to diagnose the desorption flow rate of the carbon canister.

Images