Plug-in hybrid vehicle high-pressure tank active pressure relief control method

Abstract

The application discloses a kind of plug-in hybrid vehicle high-pressure oil tank active pressure relief control methods, for controlling high-pressure oil tank active pressure relief in evaporative emission control system, comprising the following steps: S1, based on the load state of carbon can after engine start controls high-pressure oil tank pressure relief;S2, after pressure relief, record carbon can flushing time;S3, when carbon can flushing time is greater than the time threshold value of standardization, obtain current time closed loop quick fuel self-learning value f and carbon can load L;S4, according to closed loop quick fuel self-learning value f and carbon can load L judges the load state of carbon can and repeats execution step S1-S3, until engine stops operating.The application judges the load state of carbon can by introducing carbon can load and closed loop quick fuel self-learning value, controls high-pressure oil tank pressure relief according to the load state of carbon can, to efficiently coordinate the opening and closing of oil tank isolation valve, effectively release high-pressure oil tank pressure under the premise of protecting oil circuit safety.

Description

Technical Field

[0001] This invention relates to the field of automotive technology, and in particular to an active pressure relief control method for the high-pressure fuel tank of a plug-in hybrid vehicle. Background Technology

[0002] The challenges of active pressure relief during engine operation: Depressurization that is too fast, too frequent, or too excessive can cause the carbon canister to boil, and fuel to overflow from the atmospheric port of the carbon canister, causing a huge impact on the air-fuel ratio of the fuel system and affecting combustion safety; Depressurization that is too slow or too insufficient will cause the carbon canister to be flushed under most operating conditions, but the load on the fuel tank will not be effectively released, meaning that the carbon canister flushing process is inefficient or even ineffective. Currently, most mainstream active pressure relief solutions are based on tank pressure sensors. For ease of installation and disassembly, tank pressure sensors are typically placed on the pipeline between the tank and the tank isolation valve. The pressure changes measured during the pressure relief process cannot accurately reflect the internal pressure changes within the tank; they only reflect the pressure changes in the pipeline section where the sensor is located. This results in the tank isolation valve, controlled based on single-value calibration, only being able to slightly unload the tank load. Furthermore, if the opening and closing times of the tank isolation valve are controlled based on preset times, it leads to an extremely large matching workload and cannot adequately test all operating conditions, easily causing carbon canister boiling or excessive tank vacuum. Summary of the Invention In view of the shortcomings of the prior art, the technical problem to be solved by the present invention is to provide an active pressure relief control method for high-pressure fuel tank of plug-in hybrid vehicles that can effectively release the pressure of high-pressure fuel tank while protecting the safety of the oil circuit.

[0003] To solve the above-mentioned technical problems, one technical solution adopted by the present invention is: to provide a method for actively depressurizing the high-pressure fuel tank of a plug-in hybrid electric vehicle, used to control the active depressurization of the high-pressure fuel tank in an evaporative emission control system, comprising the following steps: S1. Control the pressure relief of the high-pressure oil tank based on the load status of the carbon canister after the engine starts; S2. After the pressure relief is completed, record the carbon canister flushing time; S3. When the carbon canister flushing time exceeds the calibrated time threshold, obtain the closed-loop rapid fuel self-learning value at the current moment. and carbon canister load ; S4. Based on the closed-loop rapid fuel self-learning value and carbon canister load Determine the load status of the carbon canister and repeat steps S1-S3 until the engine stops running.

[0004] Furthermore, step S1 includes the following sub-steps: When the carbon canister is under high load, the first pressure relief strategy is used to relieve pressure. When the carbon canister is under medium load, the second pressure relief strategy is used to relieve pressure. When the carbon canister is under low load, a third pressure relief strategy is used to relieve pressure.

[0005] Furthermore, the step of using the first pressure relief strategy includes the following sub-steps: Calculate the integral of the carbon canister flushing flow rate Obtain real-time oil tank pressure value ; Determine if the carbon canister flushing flow rate integral is satisfied. Greater than the first integration threshold And real-time oil tank pressure value Greater than the first pressure threshold ; If the conditions are met, open the fuel tank isolation valve and record the fuel tank pressure value when the fuel tank isolation valve is opened. ; When the tank pressure meets the requirement of the tank isolation valve opening Real-time oil tank pressure value The difference is greater than the first gradient threshold. When the pressure is released, close the oil tank isolation valve to end the pressure relief.

[0006] Furthermore, the step of employing the second pressure relief strategy includes the following sub-steps: Calculate the integral of the carbon canister flushing flow rate Obtain real-time oil tank pressure value ; Determine if the carbon canister flushing flow rate integral is satisfied. Greater than the second integration threshold And real-time oil tank pressure value Greater than the second pressure threshold ; If the conditions are met, open the fuel tank isolation valve and record the fuel tank pressure value when the fuel tank isolation valve is opened. ; When the tank pressure meets the requirement of the tank isolation valve opening Real-time oil tank pressure value The difference is greater than the second gradient threshold. When the pressure is released, close the oil tank isolation valve to end the pressure relief.

[0007] Furthermore, the steps for employing the third pressure relief strategy include the following sub-steps: Calculate the integral of the carbon canister flushing flow rate Obtain real-time oil tank pressure value ; Determine if the carbon canister flushing flow rate integral is satisfied. Greater than the third integration threshold And real-time oil tank pressure value Greater than the third pressure threshold ; If the conditions are met, open the fuel tank isolation valve and record the fuel tank pressure value when the fuel tank isolation valve is opened. ; When the tank pressure meets the requirement of the tank isolation valve opening Real-time oil tank pressure value The difference is greater than the third gradient threshold. When the pressure is released, close the oil tank isolation valve to end the pressure relief.

[0008] Furthermore, the carbon canister flushing flow rate integral It is obtained through the following formula: (one) In formula (1), This represents the real-time flow model value for carbon canister flushing.

[0009] Furthermore, the time threshold mentioned in step S3 is specifically as follows: When the carbon canister is under high load, the calibration range of the time threshold is 5 to 10 seconds; When the carbon canister is under medium load, the calibration range of the time threshold is 3 to 7 seconds; When the carbon canister is under low load, the time threshold calibration range is 1 second to 4 seconds.

[0010] Furthermore, the closed-loop rapid fuel self-learning value It is obtained through the following formula: (two) In formula (ii), This indicates the closed-loop fuel adjustment factor. Indicates the current moment. Represents a software execution cycle. Indicates the number of cycles.

[0011] Furthermore, the carbon canister is loaded It is obtained through the following formula: (three) In formula (iii), This represents the closed-loop rapid fuel self-learning value.

[0012] Furthermore, the method based on the closed-loop rapid fuel self-learning value... and carbon canister load The method for determining the load status of the carbon canister is as follows: When the closed-loop rapid fuel self-learning value Less than the first threshold and carbon canister load When the load exceeds the second threshold, the carbon canister is determined to be in a high-load state. When the closed-loop rapid fuel self-learning value Greater than or equal to the third threshold and carbon canister load When the value is less than or equal to the fourth threshold, the carbon canister is determined to be in a low-load state. When none of the above conditions are met, the carbon canister is in a medium load state.

[0013] The subject matter of this invention has at least the following beneficial effects: by introducing carbon canister load and closed-loop rapid fuel self-learning value to determine the load state of the carbon canister, and setting different conditions for opening the fuel tank isolation valve according to the carbon canister load state, the opening and closing of the fuel tank isolation valve can be efficiently coordinated, and the high pressure of the fuel tank can be effectively released under the premise of protecting the safety of the fuel circuit. Attached Figure Description

[0014] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a flowchart of one embodiment of the active pressure relief control method for the high-pressure fuel tank of a plug-in hybrid vehicle according to the present invention.

[0015] Figure 2 for Figure 1 The flowchart for step S1, which uses the first pressure relief strategy, is shown.

[0016] Figure 3 for Figure 1 The flowchart for step S1, which uses the second pressure relief strategy, is shown.

[0017] Figure 4 for Figure 1 The flowchart for step S1, which uses the third pressure relief strategy, is shown. Detailed Implementation

[0018] The invention will now be further described with reference to the accompanying drawings.

[0019] Please see Figure 1 This is a flowchart of an embodiment of the active pressure relief control method for the high-pressure fuel tank of a plug-in hybrid vehicle according to the present invention. This embodiment specifically includes the following steps: S1. Control the pressure relief of the high-pressure oil tank based on the load status of the carbon canister after the engine starts.

[0020] When the engine is first started, the fuel tank isolation valve has not yet opened, and the carbon canister flushing has not yet started. At this time, it is impossible to determine the load condition of the carbon canister. Therefore, when depressurizing for the first time, a default carbon canister load condition should be used to control the fuel tank depressurization. In this embodiment, it is assumed that the carbon canister is in a high load condition when depressurizing for the first time after the engine starts.

[0021] The specific method for controlling the pressure relief of the high-pressure fuel tank based on the load state of the carbon canister after engine start-up is as follows: when the carbon canister is under high load, the first pressure relief strategy is adopted; when the carbon canister is under medium load, the second pressure relief strategy is adopted; and when the carbon canister is under low load, the third pressure relief strategy is adopted.

[0022] Please see Figure 2 This is a flowchart of the pressure relief process using the first pressure relief strategy in step S1, which specifically includes the following steps: S11. Calculate the integral of the carbon canister flushing flow rate. Obtain real-time oil tank pressure value .

[0023] The carbon canister flushing flow integral The calculation formula is as follows:

[0024] in, This represents the real-time flow rate model value for carbon canister flushing. The calculation is a mature technology for carbon canister flushing control and can be directly borrowed. The carbon canister flushing flow rate is integrated after the pressure relief ends. Perform initialization to avoid affecting the next depressurization.

[0025] Real-time oil tank pressure value The pressure is constantly changing, and the current pressure of the fuel tank can be obtained in real time through the fuel tank pressure sensor.

[0026] S12. Determine if the carbon canister flushing flow rate integral is satisfied. Greater than the first integration threshold And real-time oil tank pressure value Greater than the first pressure threshold .

[0027] First integration threshold Calibration is possible, typically 10g; First pressure threshold It can be calibrated, and the typical value range is greater than or equal to 20 kPa and less than or equal to 35 kPa.

[0028] S13. If satisfied, open the tank isolation valve and record the tank pressure value when the tank isolation valve is opened. .

[0029] When the fuel tank isolation valve opens, pressure is released, allowing fuel vapors from the high-pressure fuel tank to enter the carbon canister. The fuel tank pressure value at the moment the isolation valve opens is recorded. This is the tank pressure at the start of depressurization. If this pressure is not met, return to the calculation of the carbon canister flushing flow rate integral. Obtain real-time oil tank pressure value Carbon canister flushing flow rate integral and real-time oil tank pressure value It changes constantly until the conditions for opening the oil tank isolation valve are met before depressurization occurs.

[0030] S14. Tank pressure value when the tank isolation valve is open. Real-time oil tank pressure value The difference is greater than the first gradient threshold. When the pressure is released, close the oil tank isolation valve to end the pressure relief.

[0031] Here, the tank pressure value when the tank isolation valve is open. That is, the pressure in the oil tank when depressurization begins, the real-time oil tank pressure value. That is, the pressure in the oil tank is released to the current pressure, which is the oil tank pressure value when the oil tank isolation valve opens. Real-time oil tank pressure value The difference is the pressure drop, which means the pressure drop is greater than the first gradient threshold. When the pressure relief is stopped, close the tank isolation valve to end the pressure relief; first pressure gradient threshold. It can be calibrated, and the typical value range is greater than or equal to 5 kPa and less than or equal to 8 kPa.

[0032] Please see Figure 3 This is a flowchart of the second pressure relief strategy used in step S1, which specifically includes the following steps: S11' Calculate the carbon canister flushing flow rate integral Obtain real-time oil tank pressure value .

[0033] Carbon canister flushing flow integral Calculation and real-time oil tank pressure value For details on obtaining the information, please refer to the section on pressure relief using the first pressure relief strategy; further details will not be provided here.

[0034] S12' Determine if the carbon canister flushing flow rate integral is satisfied. Greater than the second integration threshold And real-time oil tank pressure value Greater than the second pressure threshold .

[0035] Second integration threshold = First integration threshold Calibration is possible, typically 10g, for the first integral threshold deviation calibration. Typically calibrated to 0; Second pressure threshold = First pressure threshold Calibration is possible, typically with a value range greater than or equal to 20 kPa and less than or equal to 35 kPa, for the first pressure threshold deviation calibration value. It is usually calibrated to 0.

[0036] S13' If satisfied, open the tank isolation valve and record the tank pressure value when the tank isolation valve is opened. .

[0037] When the fuel tank isolation valve opens, pressure is released, allowing fuel vapors from the high-pressure fuel tank to enter the carbon canister. The fuel tank pressure value at the moment the isolation valve opens is recorded. This is the tank pressure at the start of depressurization. If this pressure is not met, return to the calculation of the carbon canister flushing flow rate integral. Obtain real-time oil tank pressure value Carbon canister flushing flow rate integral and real-time oil tank pressure value It changes constantly until the conditions for opening the oil tank isolation valve are met before depressurization occurs.

[0038] S14', The oil tank pressure value when the oil tank isolation valve is opened. Real-time oil tank pressure value The difference is greater than the second gradient threshold. When the pressure is released, close the oil tank isolation valve to end the pressure relief.

[0039] Here, the tank pressure value when the tank isolation valve is open. That is, the pressure in the oil tank when depressurization begins, the real-time oil tank pressure value. That is, the pressure in the oil tank is released to the current pressure, which is the oil tank pressure value when the oil tank isolation valve opens. Real-time oil tank pressure value The difference is the pressure drop, meaning the pressure drop is greater than the second gradient threshold. When the pressure relief is stopped, close the tank isolation valve to end the pressure relief; second pressure gradient threshold. It can be calibrated, and the typical value range is greater than or equal to 5 kPa and less than or equal to 8 kPa.

[0040] Please see Figure 4 This is a flowchart of the third pressure relief strategy used in step S1, which specifically includes the following steps: S11”, Calculate the carbon canister flushing flow rate integral Obtain real-time oil tank pressure value .

[0041] Carbon canister flushing flow integral Calculation and real-time oil tank pressure value For details on obtaining the information, please refer to the section on pressure relief using the first pressure relief strategy; further details will not be provided here.

[0042] S12" Determine if the carbon canister flushing flow rate integral is satisfied. Greater than the third integration threshold And real-time oil tank pressure value Greater than the third pressure threshold .

[0043] Third integration threshold = Second integration threshold For calculations, please refer to the content on pressure relief using the second pressure relief strategy, and the second integral threshold deviation calibration. Typically calibrated to 0; Third pressure threshold = Second pressure threshold For calculations, please refer to the section on pressure relief using the second pressure relief strategy, and the calibration of the second pressure threshold deviation. It is usually calibrated to 0.

[0044] If S13 is satisfied, then open the tank isolation valve and record the tank pressure value when the tank isolation valve is opened. .

[0045] When the fuel tank isolation valve opens, pressure is released, allowing fuel vapors from the high-pressure fuel tank to enter the carbon canister. The fuel tank pressure value at the moment the isolation valve opens is recorded. This is the tank pressure at the start of depressurization. If this pressure is not met, return to the calculation of the carbon canister flushing flow rate integral. Obtain real-time oil tank pressure value Carbon canister flushing flow rate integral and real-time oil tank pressure value It changes constantly until the conditions for opening the oil tank isolation valve are met before depressurization occurs.

[0046] S14" When the tank pressure value is satisfied when the tank isolation valve is open Real-time oil tank pressure value The difference is greater than the third gradient threshold. When the pressure is released, close the oil tank isolation valve to end the pressure relief.

[0047] Here, the tank pressure value when the tank isolation valve is open. That is, the pressure in the oil tank when depressurization begins, the real-time oil tank pressure value. That is, the pressure in the oil tank is released to the current pressure, which is the oil tank pressure value when the oil tank isolation valve opens. Real-time oil tank pressure value The difference is the pressure drop, meaning the pressure drop is greater than the third gradient threshold. At this time, close the tank isolation valve to end the pressure relief; third pressure gradient threshold. It can be calibrated, and the typical value range is greater than or equal to 5 kPa and less than or equal to 8 kPa.

[0048] S2. After the pressure relief is completed, record the carbon canister flushing time.

[0049] S3. When the carbon canister flushing time exceeds the calibrated time threshold, obtain the closed-loop rapid fuel self-learning value at the current moment. and carbon canister load .

[0050] When the fuel tank isolation valve is opened, there will be some fuel loss. The closed-loop rapid fuel self-learning value recorded at this time... and carbon canister load The deviation is significant, so the timer should only start recording the carbon canister flushing time after the pressure relief is complete and the fuel tank isolation valve is closed. The closed-loop rapid fuel self-learning value should only be recorded after the carbon canister flushing time exceeds the set time threshold. and carbon canister load Only then can the amount of fuel vapor in the carbon canister be characterized.

[0051] The set flushing time threshold varies depending on the load condition of the carbon canister. When the carbon canister is under high load, the time threshold is calibrated in the range of 5 to 10 seconds; when the carbon canister is under medium load, the time threshold is calibrated in the range of 3 to 7 seconds; and when the carbon canister is under low load, the time threshold is calibrated in the range of 1 to 4 seconds.

[0052] The closed-loop rapid fuel self-learning value The calculation formula is as follows:

[0053] in, This refers to the closed-loop fuel adjustment factor. The calculation of closed-loop fuel adjustment factor is a mature technology and will not be elaborated here. It is constantly changing; This indicates the current moment, i.e., the moment when the carbon canister flushing time exceeds the set time threshold; This represents a software execution cycle, specifically the calculation cycle defined in this implementation method. Set to 20 milliseconds; This represents the number of cycles, used to calculate the closed-loop rapid fuel self-learning value. To be more accurate, this calculation method uses the average of multiple periods. It should be understood that different implementation methods may vary. The value of can be different. In this embodiment, The value is set to 5, meaning the average value calculated over 5 cycles is used to represent the closed-loop rapid fuel self-learning value at the current moment.

[0054] The carbon canister load The calculation formula is as follows:

[0055] in, This represents the closed-loop rapid fuel self-learning value.

[0056] S4. Based on the closed-loop rapid fuel self-learning value and carbon canister load Determine the load status of the carbon canister and repeat steps S1-S3 until the engine stops running.

[0057] Carbon canister load status It can only reflect the amount of fuel vapor inside the carbon canister over a period of time during the flushing process. The most direct manifestation of the impact of fuel inside the carbon canister on the combustion of the engine fuel system is the closed-loop rapid fuel self-learning value. To ensure effective unloading of the high-pressure oil tank while maintaining the safety of the oil circuit, the carbon canister load needs to be considered in conjunction with other factors. and closed-loop rapid fuel self-learning value .

[0058] When the closed-loop rapid fuel self-learning value Less than the first threshold and carbon canister load When the value exceeds the second threshold, the carbon canister is considered to be under high load. The first threshold is typically calibrated to 0.9, and the second threshold is greater than or equal to 6 and less than or equal to 8. When there is no fuel shock, the closed-loop fast fuel self-learning value is 1, therefore the closed-loop fast fuel self-learning value... Less than the first threshold and carbon canister load A value greater than the second threshold indicates that the fuel vapor flushed from the carbon canister at the current moment causes the closed-loop fuel control rapid self-learning value to be in a state much less than 1, which has a significant impact on the closed-loop fuel control. Furthermore, a large amount of fuel vapor has been flushed out over a period of time, indicating that the carbon canister is still under high load. It is necessary to limit the opening of the fuel tank isolation valve to prevent a large amount of fuel vapor from entering the carbon canister from the high-pressure fuel tank and thus avoid fuel vapor overflow.

[0059] When the closed-loop rapid fuel self-learning value Greater than or equal to the third threshold and carbon canister load When the value is less than or equal to the fourth threshold, the carbon canister is considered to be under low load. The third threshold is typically calibrated to 0.94, and the fourth threshold is greater than or equal to 3 and less than or equal to 6. Closed-loop rapid fuel self-learning value. Greater than or equal to the third threshold and carbon canister load A value less than or equal to the fourth threshold indicates that the fuel vapor flushed from the carbon canister at the current moment has a relatively small impact on the closed-loop fuel control, and that a large amount of fuel vapor has not been flushed out in the past period. The carbon canister is currently in a state of being effectively emptied and desorbed, which means that the carbon canister is in a low-load state and has a large capacity to withstand the fuel vapor released from the high-pressure fuel tank. At this time, the opening restriction of the fuel tank isolation valve can be relaxed as much as possible to allow more fuel vapor to enter the carbon canister from the high-pressure fuel tank.

[0060] When none of the above conditions are met, the carbon canister is under medium load. At the current moment, the fuel vapor flushed from the carbon canister has little impact on the closed-loop fuel control, but a large amount of fuel vapor has already been flushed out over the past period. Currently, it remains in an intermediate state regarding whether the carbon canister has been effectively emptied and desorbed. Therefore, it can be determined that the carbon canister is under medium load and has sufficient capacity to withstand fuel vapor released from the high-pressure fuel tank. At this point, the opening restriction on the fuel tank isolation valve can be appropriately relaxed, allowing some fuel vapor to enter the carbon canister from the high-pressure fuel tank.

[0061] The active pressure relief control method for high-pressure fuel tank in plug-in hybrid electric vehicles of the present invention determines the load state of the carbon canister by introducing carbon canister load and closed-loop rapid fuel self-learning value. Different conditions for opening the fuel tank isolation valve are set according to the carbon canister load state, thereby efficiently coordinating the opening and closing of the fuel tank isolation valve and effectively releasing the pressure of the high-pressure fuel tank while protecting the fuel circuit.

[0062] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A plug-in hybrid vehicle high-pressure tank active decompression control method characterized by, The method for controlling the active depressurization of the high-pressure oil tank in an evaporative emission control system includes the following steps: S1. Control the pressure relief of the high-pressure oil tank based on the load status of the carbon canister after the engine starts; S2. After the pressure relief is completed, record the carbon canister flushing time; S3、when the carbon tank flushing time is greater than the calibrated time threshold, acquiring a current time closed-loop quick fuel self-learning value and the carbon tank load ; S4, determining the closed loop quick fuel self-learning value and carbon canister load determining the load state of the carbon canister and repeatedly performing steps S1-S3 until the engine is stopped; Step S1 includes the following sub-steps: When the carbon canister is under high load, a first pressure relief strategy is employed to relieve pressure. The steps of employing the first pressure relief strategy include the following sub-steps: Computing carbon can flush flow integral , obtaining real-time tank pressure value ; determining whether the carbon can flushing flow integral satisfies a condition greater than a first integral threshold value and a real-time tank pressure value greater than a first pressure threshold value ; wherein the first integral threshold value may be calibrated to 10 g, and the first pressure threshold value may be calibrated to a value range of greater than or equal to 20 kPa and less than or equal to 35 kPa; If yes, open the tank isolation valve and record the tank pressure value at the time of opening the tank isolation valve ; When the tank pressure meets the requirement of the tank isolation valve opening Real-time oil tank pressure value The difference is greater than the first gradient threshold. When the pressure relief is complete, close the oil tank isolation valve. When the carbon canister is under medium load, a second pressure relief strategy is employed to relieve pressure. The steps of employing the second pressure relief strategy include the following sub-steps: Calculate the integral of the carbon canister flushing flow rate Obtain real-time oil tank pressure value ; Determine if the carbon canister flushing flow rate integral is satisfied. Greater than the second integration threshold And real-time oil tank pressure value Greater than the second pressure threshold Among them, the second integration threshold = First integral threshold deviation calibration Calibration set to 0; Second pressure threshold = First pressure threshold deviation calibration The calibration is set to 0; If the conditions are met, open the fuel tank isolation valve and record the fuel tank pressure value when the fuel tank isolation valve is opened. ; When the tank pressure meets the requirement of the tank isolation valve opening Real-time oil tank pressure value The difference is greater than the second gradient threshold. When the pressure relief is complete, close the oil tank isolation valve. When the carbon canister is under low load, a third pressure relief strategy is employed to relieve pressure. The steps for employing this third pressure relief strategy include the following sub-steps: Calculate the integral of the carbon canister flushing flow rate Obtain real-time oil tank pressure value ; Determine if the carbon canister flushing flow rate integral is satisfied. Greater than the third integration threshold And real-time oil tank pressure value Greater than the third pressure threshold Among them, the third integration threshold = Second integral threshold deviation calibration Calibration set to 0; Third pressure threshold = Second pressure threshold deviation calibration The calibration is set to 0; If the conditions are met, open the fuel tank isolation valve and record the fuel tank pressure value when the fuel tank isolation valve is opened. ; When the tank pressure meets the requirement of the tank isolation valve opening Real-time oil tank pressure value The difference is greater than the third gradient threshold. When the pressure is released, close the oil tank isolation valve to end the pressure relief.

2. The active pressure relief control method for the high-pressure fuel tank of a plug-in hybrid vehicle as described in claim 1, characterized in that, The carbon canister flushing flow integral It is obtained through the following formula: (one) In formula (1), This represents the real-time flow model value for carbon canister flushing.

3. The active pressure relief control method for the high-voltage fuel tank of a plug-in hybrid vehicle as described in claim 1, characterized in that, The time threshold mentioned in step S3 is specifically: When the carbon canister is under high load, the calibration range of the time threshold is 5 to 10 seconds; When the carbon canister is under medium load, the calibration range of the time threshold is 3 to 7 seconds; When the carbon canister is under low load, the time threshold calibration range is 1 second to 4 seconds.

4. The active pressure relief control method for the high-pressure fuel tank of a plug-in hybrid vehicle as described in claim 1, characterized in that, The closed-loop rapid fuel self-learning value It is obtained through the following formula: (two) In formula (ii), This indicates the closed-loop fuel adjustment factor. Indicates the current moment. Represents a software execution cycle. Indicates the number of cycles.

5. The active pressure relief control method for the high-voltage fuel tank of a plug-in hybrid vehicle as described in claim 1, characterized in that, The carbon canister load It is obtained through the following formula: (three) In formula (iii), This represents the closed-loop rapid fuel self-learning value.

6. The active pressure relief control method for the high-voltage fuel tank of a plug-in hybrid vehicle as described in claim 1, characterized in that, The method based on closed-loop rapid fuel self-learning value and carbon canister load The method for determining the load status of the carbon canister is as follows: When the closed-loop rapid fuel self-learning value Less than the first threshold and carbon canister load When the load exceeds the second threshold, the carbon canister is determined to be in a high-load state. When the closed-loop rapid fuel self-learning value Greater than or equal to the third threshold and carbon canister load When the value is less than or equal to the fourth threshold, the carbon canister is determined to be in a low-load state. When none of the above conditions are met, the carbon canister is in a medium load state.

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