CN115111091A - Method for diagnosing fuel leakage of evaporation system of fuel vehicle - Google Patents
Method for diagnosing fuel leakage of evaporation system of fuel vehicle Download PDFInfo
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- CN115111091A CN115111091A CN202210453301.4A CN202210453301A CN115111091A CN 115111091 A CN115111091 A CN 115111091A CN 202210453301 A CN202210453301 A CN 202210453301A CN 115111091 A CN115111091 A CN 115111091A
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- leakage
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- 238000001704 evaporation Methods 0.000 title claims abstract description 64
- 230000008020 evaporation Effects 0.000 title claims abstract description 64
- 239000000446 fuel Substances 0.000 title claims abstract description 55
- 238000000034 method Methods 0.000 title claims abstract description 36
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 91
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 91
- 238000009423 ventilation Methods 0.000 claims abstract description 14
- 238000003745 diagnosis Methods 0.000 claims description 57
- 238000011010 flushing procedure Methods 0.000 claims description 20
- 239000007789 gas Substances 0.000 claims description 10
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 5
- 230000004913 activation Effects 0.000 claims description 4
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 4
- 230000007613 environmental effect Effects 0.000 claims description 4
- 229910052760 oxygen Inorganic materials 0.000 claims description 4
- 239000001301 oxygen Substances 0.000 claims description 4
- 238000004140 cleaning Methods 0.000 claims description 3
- 238000003860 storage Methods 0.000 claims description 3
- 230000015556 catabolic process Effects 0.000 claims description 2
- 238000006731 degradation reaction Methods 0.000 claims description 2
- 230000000737 periodic effect Effects 0.000 claims description 2
- 238000005406 washing Methods 0.000 claims description 2
- 230000009467 reduction Effects 0.000 abstract description 5
- 238000011161 development Methods 0.000 abstract description 4
- 239000003921 oil Substances 0.000 description 37
- 238000012544 monitoring process Methods 0.000 description 13
- 230000008569 process Effects 0.000 description 11
- 230000008859 change Effects 0.000 description 9
- 238000001514 detection method Methods 0.000 description 8
- 238000009834 vaporization Methods 0.000 description 8
- 230000008016 vaporization Effects 0.000 description 8
- 238000010586 diagram Methods 0.000 description 7
- 238000012937 correction Methods 0.000 description 4
- 238000011084 recovery Methods 0.000 description 4
- 238000003795 desorption Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 230000005540 biological transmission Effects 0.000 description 2
- 238000004891 communication Methods 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 239000000295 fuel oil Substances 0.000 description 2
- 238000002347 injection Methods 0.000 description 2
- 239000007924 injection Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000005086 pumping Methods 0.000 description 2
- 239000004215 Carbon black (E152) Substances 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000002405 diagnostic procedure Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 239000002828 fuel tank Substances 0.000 description 1
- 230000006870 function Effects 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 150000002430 hydrocarbons Chemical class 0.000 description 1
- 239000002440 industrial waste Substances 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 239000010734 process oil Substances 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000010926 purge Methods 0.000 description 1
Images
Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- F02M25/00—Engine-pertinent apparatus for adding non-fuel substances or small quantities of secondary fuel to combustion-air, main fuel or fuel-air mixture
- F02M25/08—Engine-pertinent apparatus for adding non-fuel substances or small quantities of secondary fuel to combustion-air, main fuel or fuel-air mixture adding fuel vapours drawn from engine fuel reservoir
- F02M25/0809—Judging failure of purge control system
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D41/00—Electrical control of supply of combustible mixture or its constituents
- F02D41/22—Safety or indicating devices for abnormal conditions
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D41/00—Electrical control of supply of combustible mixture or its constituents
- F02D41/22—Safety or indicating devices for abnormal conditions
- F02D2041/224—Diagnosis of the fuel system
- F02D2041/225—Leakage detection
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/10—Internal combustion engine [ICE] based vehicles
- Y02T10/40—Engine management systems
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Supplying Secondary Fuel Or The Like To Fuel, Air Or Fuel-Air Mixtures (AREA)
Abstract
According to the method for diagnosing the fuel leakage of the evaporation system of the fuel vehicle, disclosed by the invention, under the idling working condition of the engine, the carbon tank electromagnetic valve is opened to form a vacuum degree with the air inlet manifold, after the required vacuum degree is achieved, the carbon tank electromagnetic valve and the carbon tank ventilation stop valve are closed, and the speed of the evaporation system recovering the normal pressure is monitored in a closed space to further judge the actual leakage amount, so that whether the evaporation system has the leakage or not is judged, the problems of reduction of the electric balance performance of the whole vehicle and overhigh cost are solved, the electric balance of the whole vehicle is influenced, and the development cost is greatly saved.
Description
Technical Field
The invention relates to the technical field of fuel vehicle control, in particular to a method for diagnosing fuel leakage of an evaporation system of a fuel vehicle.
Background
With the development of industry and science and technology, particularly the rapid rise of the automobile industry, the influence on the environment caused by industrial waste gas and automobile exhaust is increasingly severe, and in order to further reduce and limit the pollution of the automobile exhaust, the national GB18532-2016 light automobile pollutant emission limit value and the measurement method have made strict requirements on automobile emissions. The six state emission regulations increase the requirements on the diagnosis of the fuel evaporation system, and the OBD vehicle-mounted diagnosis system is required to have the capability of monitoring the leakage fault diagnosis of the evaporation system with the thickness of 1mm or more, and the IUPR rate meets 0.226.
The scheme that the diagnosis of present domestic host computer factory was taken vehicle fuel oil vaporization system mostly uses DMTL as leading, and DMTL is an external vaporization system leakage monitoring module, and its detection principle is through the air pump to the interior pump gas of oil tank system for oil tank pressure rises, and the indirect condition that reflects the oil tank pressure rise of air pump current size, thereby the leakproofness of aassessment oil tank system, the judgement standard is as follows:
1) if a closed tank system: when the air pump works, the pressure of the oil tank rises, and the current rises rapidly. 2) If the fuel tank system has leakage: there is no or little tank pressure rise and the pump current is slow or does not rise.
According to the scheme, a fuel leakage diagnosis module needs to be additionally arranged, the cost of the whole vehicle is increased, and DMTL needs to stabilize the working condition when a 0.5mm leakage hole reference current is formed, needs to be diagnosed after the whole vehicle is powered off, and has influence on the electric balance performance of the whole vehicle; the scheme becomes a great limiting factor in the current fuel vehicle development process.
Disclosure of Invention
The method comprises the steps that an engine is opened under an idling working condition to form a vacuum degree with an air inlet manifold through a carbon tank electromagnetic valve, after the required vacuum degree is achieved, the carbon tank electromagnetic valve and a carbon tank ventilation stop valve are closed, and the speed of the evaporation system recovering to the normal pressure is monitored in a closed space so as to judge the actual leakage amount.
The technical scheme adopted for realizing the invention is as follows: a method for diagnosing fuel leakage of an evaporation system of a fuel vehicle is characterized by comprising the following steps:
1) and (3) carrying out carbon tank flushing calibration:
(1) calibrating the delay time of the carbon tank electromagnetic valve:
under the idle working condition, the carbon tank electromagnetic valve delay time calibration adopts a direct calibration method or an indirect calibration method;
(2) calibrating the periodic characteristics of the carbon tank electromagnetic valve:
reducing the delay time of the carbon tank electromagnetic valve, and marking the period characteristic of the carbon tank electromagnetic valve as long;
(3) calibrating the activation condition of the carbon tank flushing function:
when the vehicle is in fuel cut and oxygen cleaning, the air-fuel ratio condition is quitted; the water temperature condition meets the preset condition of an evaporation system; presetting an engine starting time counting condition; the pressure of the oil tank has no obvious fluctuation; the voltage is maintained to be normal;
2) and (3) diagnosing and calibrating the leakage of the evaporation system:
(1) the leakage diagnosis of the evaporation system is started, and the following conditions are achieved:
firstly, the water temperature is 4-35 ℃;
the environmental temperature is 4-35 ℃;
③ the engine is started and tnsez is more than 600 s;
setting an idle speed B _ llr, wherein the speed is less than or equal to 3 km/h;
the voltage of the storage battery is 11-16V;
sixthly, the pressure pttp _ w of the oil tank is-25 to 10 hPa;
the ratio pspu of the manifold to the ambient pressure is less than or equal to 0.7;
(8 g) integrating the flushing flow of the carbon canister
(2) An evaporative system leak diagnostic abort comprising one of the following conditions:
firstly, the pressure of the oil tank is continuously reduced beyond a limit value after the vacuumizing is finished;
oil gas is evaporated violently;
thirdly, oil gas is seriously condensed;
fourthly, the actual washing amount has overlarge deviation with the target;
after closing the carbon canister and flushing, the pressure of the oil tank is not stable for a long time;
(3) judging the diagnosis end condition of the evaporation system:
the first stage is as follows: closing a carbon tank stop vent valve, opening a carbon tank electromagnetic valve, and increasing the vacuum degree of an evaporation system due to the vacuum degree of an air inlet manifold; if the vacuum degree of the evaporation system is not increased, the system detects a coarse leakage fault and stops diagnosis;
and a second stage: when the evaporation system reaches the required vacuum degree, the carbon tank electromagnetic valve is closed, the carbon tank electromagnetic valve and the carbon tank stop ventilation valve are both closed, the vacuum degree of the evaporation system is degraded due to leakage, and the 1mm leakage of the evaporation system is detected according to the degradation gradient;
and a third stage: and after the fuel leakage diagnosis of the evaporation system is finished, the carbon tank stop ventilation valve is opened and keeps a normally open state, and the carbon tank electromagnetic valve is closed.
Further, the direct calibration method comprises the following steps:
1) setting the minimum duty ratio opening of the carbon tank electromagnetic valve, wherein the carbon tank electromagnetic valve is in a closed state due to the existence of delay time;
2) and gradually adjusting the duty ratio opening of the electromagnetic valve until the value of the flow sensor changes, and determining the delay time of the carbon tank electromagnetic valve.
Further, the indirect calibration method comprises the following steps:
1) setting the frequency of the carbon tank electromagnetic valve, and gradually opening the carbon tank electromagnetic valve;
2) and gradually adjusting the duty ratio opening of the electromagnetic valve until the value of the flow sensor changes, at the moment, offsetting the output duty ratio and the delay time, and calculating the delay time.
The method for diagnosing the fuel leakage of the evaporation system of the fuel vehicle has the beneficial effects that:
1. a method for diagnosing fuel leakage of an evaporation system of a fuel vehicle comprises the steps that after a vehicle is determined to meet preset diagnosis enabling conditions, the working state of a carbon tank electromagnetic valve and a carbon tank stop ventilation valve is controlled through an engine control unit, and the pressure value in the evaporation system is monitored, so that whether leakage exists in the evaporation system is judged, the situation that a DMTL scheme needs to be operated at a post-operation stage is avoided, the influence on the electric balance of the whole vehicle is avoided, and meanwhile, the development cost is greatly saved;
2. a method for diagnosing fuel leakage of an evaporation system of a fuel vehicle solves the problems of low electric balance performance and high cost of the whole vehicle in operation after the whole vehicle is powered off, can meet the requirements of regulations and effectively ensures the OBD diagnosis IUPR rate.
Drawings
FIG. 1 is a block diagram of a carbon canister flush calibration;
FIG. 2 is a block schematic diagram of a vaporization system diagnostic;
FIG. 3 is a schematic diagram of a gross leak diagnostic method of diagnosing fuel leaks in an evaporative system of a fuel vehicle;
FIG. 4 is a schematic view of a complete leak diagnosis of a method for diagnosing fuel leaks in an evaporative system of a fuel vehicle.
Detailed Description
The present invention will be described in further detail with reference to the accompanying fig. 1-4 and the specific embodiments described herein, which are provided for illustration only and are not intended to limit the invention.
When the vehicle is in an idling working condition, the carbon tank electromagnetic valve is opened, fuel oil leakage diagnosis is carried out in the carbon tank desorption process, the state information of the vehicle is monitored through the engine control unit ECU, and whether the current vehicle meets the preset conditions or not is judged according to the state information.
If the preset conditions are met, closing the carbon tank stop vent valve and opening the carbon tank electromagnetic valve with a certain opening degree through the engine control unit ECU, gradually forming negative pressure in the evaporation system, and acquiring the pressure of an oil tank in the evaporation system in real time. If the pressure of the oil tank cannot be rapidly reduced in the negative pressure forming process and is smaller than the preset reduction rate of the pressure of the oil tank preset by the engine control unit, monitoring that a coarse leakage fault occurs in the evaporation system; if the pressure drop rate meets a preset value, when the pressure drops to a certain preset value, an Engine Control Unit (ECU) closes a carbon tank ventilation stop valve, and diagnosis enters a pressure maintaining diagnosis stage; acquiring the pressure change rate of an oil tank in the pressure maintaining stage, and if the pressure recovery pressure rate of the oil tank in the pressure maintaining stage is less than the preset rate reported by the fault, determining that no leakage fault occurs in the evaporation system; if the pressure recovery pressure rate of the oil tank in the pressure maintaining stage is greater than the preset rate reported by the fault, the leakage fault of the evaporation system occurs; and after the diagnosis is finished completely, the ECU controls the carbon tank stop vent valve and the carbon tank electromagnetic valve to restore the original states, and the diagnosis is finished completely.
The basic working principle of the fuel leakage diagnosis method of the evaporation system of the fuel vehicle is as follows: the engine is under the idle operating mode, opens through the carbon tank solenoid valve and forms the vacuum with air intake manifold, closes carbon tank solenoid valve and carbon tank ventilation stop valve after reaching the requirement vacuum, and the rate that monitoring vaporization system resumes the ordinary pressure under airtight space then judges the size of actual leakage quantity.
Example 1:
FIG. 1 is a schematic diagram of a carbon canister flushing calibration module according to the present invention. The carbon tank flushing calibration comprises the following steps: the device comprises a carbon tank flushing activation condition module, a carbon tank flushing target flow module, a carbon tank flushing process mixed gas self-learning correction module, a carbon tank flushing process oil injection quantity correction module, an actual flow calculation module, an oxygen sensor signal processing module and a mixed gas control module.
A canister purge activation condition module for monitoring whether the current vehicle meets a preset diagnostic enable condition, including but not limited to the following conditions: the air-fuel ratio condition exits when the vehicle is in fuel cut and oxygen cleaning; the water temperature condition meets the preset condition of an evaporation system; presetting an engine starting time counting condition; non-offline detection; the pressure of the oil tank does not fluctuate obviously; the voltage is maintained to be normal; if the diagnosis condition is met, sending a diagnosis condition meeting state bit through an engine control unit;
the actual flow calculating module is used for monitoring the current atmospheric environment pressure of the vehicle and the pressure of the intake manifold, the pressures are monitored by an engine control power supply ECU, and the actual flow in the current carbon tank flushing process is calculated by combining the opening degree of a carbon tank electromagnetic valve;
the carbon tank flushing target flow module is used for calculating the control period and the duty ratio of the carbon tank electromagnetic valve at the next moment by combining the current actual desorption flow, and is used for controlling the carbon tank electromagnetic valve so as to adjust the desorption flow; in calibrating the canister valve control period, the period should be as long as possible in order to minimize the effect of the delay time. The small duty cycle results in long canister valve closing times, which results in uneven hydrocarbon distribution. However, when the duty cycle is small, the flow through the canister valve is also small, and thus has limited adverse effects on canister flushing. If the engine speed is increased during a long control period, the uneven distribution of fuel and air increases with the increase of the engine speed, and in order to avoid this, the control period of the canister valve should be reduced as the engine speed increases.
And the self-learning deviation correction module of the mixed gas in the carbon tank flushing process calculates the content of the oil vapor in the carbon tank flushing flow, corrects the parameters of the mixed gas module, removes the overcompensation of the oil vapor in the carbon tank flushing process, and further completes the correction of the relative fuel injection amount in the carbon tank flushing process.
Example 2:
referring to fig. 2, a block diagram of the evaporative system diagnostic apparatus according to the present invention is shown, the fuel diagnostic apparatus comprising: the device comprises a processor, a memory, a carbon tank electromagnetic valve, a carbon tank ventilation stop valve, an evaporation pipeline and a communication bus. The communication bus is used for realizing signals among the components, the memory can be a high-speed RAM memory or a stable NVM memory, and the memory can be a storage device independent of the processor.
As shown in fig. 2, the memory may include an engine control system and a fuel evaporation system leak diagnostic program, and the processor may invoke the fuel evaporation system leak diagnostic program from the memory and perform the following operations:
monitoring the state information of the vehicle through an Engine Control Unit (ECU) when the vehicle runs and is in an idle state; judging whether the current vehicle meets a preset diagnosis enabling condition or not according to the described state information; if the current vehicle meets the preset diagnosis enabling conditions, closing the carbon tank ventilation stop valve through the engine control unit, and opening the carbon tank electromagnetic valve to a preset opening degree to enable negative pressure to be formed in the evaporation system; then closing the carbon tank electromagnetic valve to form a sealed space; acquiring a pressure change value of an oil tank in an evaporation system, and determining whether the evaporation system leaks or not according to the pressure change;
the processor may invoke the fuel vaporization system leak diagnostic routine from the memory and perform the following operations:
and acquiring a voltage value output by the pressure sensor through an engine control unit ECU, converting the voltage value into a corresponding evaporation system pressure value, and continuously recording. Calculating a pressure change value in the evaporation system according to the pressure values of the plurality of pressure sensors;
and comparing the pressure change value with a reference pressure change value, and determining whether the evaporation system has leakage according to a comparison result.
The processor may invoke the fuel vaporization system leak diagnostic routine from the memory and perform the following operations:
monitoring, by the engine control unit ECU, status flag bit information of a power status, a leak diagnosis output status, a safety status, an oil level status, a leak request transmission status, and/or an atmospheric pressure status of a vehicle;
and determining whether the current vehicle meets the basic condition of leakage diagnosis according to the state identification bit information.
The processor may invoke the fuel vaporization system leak diagnostic routine from the memory and perform the following operations:
when the carbon tank ventilation stop valve is closed and the carbon tank electromagnetic valve is opened through the engine control unit ECU, the negative pressure pumping process is carried out at the moment, and the pressure sensor of the oil tank carries out pressure monitoring;
and recording the negative pressure reduction rate in the negative pressure pumping stage, comparing the pressure change value with a reference pressure change value, and determining whether the evaporation system leaks or not according to the comparison result. If the rate is less than the rate, it is determined that a coarse leak exists.
The processor may invoke the fuel vaporization system leak diagnostic routine from the memory and perform the following operations:
the preset diagnosis enabling conditions include a diagnosis leakage basic condition, a leakage diagnosis environmental condition, a lighting condition, a diagnosis leakage operation condition, and an engine operation state.
Example 3:
as shown in fig. 3, which is a schematic diagram of rough leakage diagnosis of the method for diagnosing fuel leakage of an evaporation system of a fuel vehicle according to the present invention, after a vehicle enters an idle operation condition and operates for a period of time under the idle operation condition, vehicle state information is monitored by an engine control unit ECU, where the time of the idle operation condition can be set according to an actual situation, and the method is preferably 10 s; after the vehicle is powered off and flameout reaches a preset time, state information of the vehicle is obtained through an engine control unit ECU, wherein the state information comprises self state information of the vehicle, environment state information and the like, such as engine running time, oil level, ambient temperature, atmospheric pressure, refueling request, component failure and the like.
After the engine control unit ECU acquires the state information, whether the current vehicle meets preset diagnosis enabling conditions is judged according to the acquired state information, wherein the preset diagnosis enabling conditions can comprise basic diagnosis leakage conditions, leakage diagnosis environment conditions, lighting conditions, diagnosis leakage operation conditions, engine running states and the like. The diagnosis enabling condition is preset by a user and can be adjusted according to actual requirements, and comprises setting of conditions related to vehicle fuel leakage detection and setting of a value range when the diagnosis condition is met, wherein if the vehicle fuel leakage detection needs to meet the requirements that the current vehicle oil pressure is 15% -85%, the current environment temperature is 4-35 ℃, the current altitude is 2440 m or less, namely the current atmospheric pressure is 72kpa or more, when the conditions are all in an allowable range, the current vehicle can be judged to meet the preset diagnosis enabling condition, and the fuel leakage detection can be carried out; when any one of the above conditions is not within the allowable range, it may be determined that the current vehicle does not satisfy the preset diagnosis enabling condition, and it is necessary to wait for the next stage to make determination.
And judging whether the current vehicle meets the preset conditions or not according to the state information, if so, closing a carbon tank stop vent valve and opening a carbon tank electromagnetic valve with a certain opening through an engine control unit, gradually forming negative pressure in the evaporation system, and acquiring the pressure of an oil tank in the evaporation system in real time. If the pressure of the oil tank cannot be rapidly reduced in the negative pressure forming process and is smaller than the preset reduction rate of the pressure of the oil tank preset by the engine control unit, monitoring that a coarse leakage fault occurs in the evaporation system;
as mentioned above, when the ECU detects that the evaporation system has coarse leakage, the carbon tank ventilation stop valve is opened to recover the normal control of the engine. Monitoring, by the engine control unit ECU, status flag bit information of a power supply status, a leak diagnosis output status, a safety status, an oil level status, a leak request transmission status, and/or an atmospheric pressure status of the vehicle.
Example 4:
as shown in fig. 4, which is a complete leakage diagnosis diagram of the method for diagnosing fuel leakage of an evaporation system of a fuel vehicle according to the present invention, after the vehicle enters an idle operation condition and operates for a period of time under the idle operation condition, the vehicle state information is monitored by an engine control unit ECU. The time of the idle operation condition can be set according to actual conditions, and the time is preferably 10 s. After the vehicle is powered off and flameout reaches a preset time, state information of the vehicle is obtained through an engine control unit ECU, wherein the state information comprises vehicle self state information, environment state information and the like, such as engine running time, oil level, environment temperature, atmospheric pressure, refueling request, component failure and the like.
And after the engine control unit ECU acquires the state information, judging whether the current vehicle meets a preset diagnosis enabling condition according to the acquired state information. The preset diagnosis enabling condition may include a diagnosis leak basic condition, a leak diagnosis environmental condition, a lighting condition, a diagnosis leak operation condition, an engine operation state, and the like. The diagnosis enabling condition is preset by a user and can be adjusted according to actual requirements, and comprises setting of conditions related to vehicle fuel leakage detection and setting of a value range when the diagnosis conditions are met, and if the vehicle fuel leakage detection needs to meet the conditions that the current vehicle oil pressure is 15% -85%, the current environment temperature is 4 ℃ -35 ℃, the current altitude is 2440 m or less, namely the current atmospheric pressure is 72kpa or more, when the conditions are all in an allowable range, the current vehicle can be judged to meet the preset diagnosis enabling condition, and the fuel leakage detection can be carried out; when any one of the above conditions is not within the allowable range, it may be determined that the current vehicle does not satisfy the preset diagnosis enabling condition, and it is necessary to wait for the next stage to make determination.
Monitoring the state information of the vehicle through the ECU, and judging whether the current vehicle meets the preset conditions or not according to the state information; if the preset conditions are met, the carbon tank stop vent valve is closed and the carbon tank electromagnetic valve with a certain opening degree is opened through the engine control unit, negative pressure is gradually formed in the evaporation system, and the pressure of an oil tank in the evaporation system is obtained in real time.
If the pressure of the oil tank cannot be rapidly reduced in the negative pressure forming process and is smaller than the preset reduction rate of the pressure of the oil tank preset by the engine control unit, monitoring that a coarse leakage fault occurs in the evaporation system;
if the pressure drop rate meets a preset value, when the pressure drops to a certain preset value, an Engine Control Unit (ECU) closes a carbon tank ventilation stop valve, and diagnosis enters a pressure maintaining diagnosis stage;
acquiring the pressure change rate of an oil tank in the pressure maintaining stage, and if the pressure recovery pressure rate of the oil tank in the pressure maintaining stage is less than the preset rate reported by the fault, determining that no leakage fault occurs in the evaporation system; if the pressure recovery pressure rate of the oil tank in the pressure maintaining stage is greater than the preset rate reported by the fault, the leakage fault of the evaporation system occurs;
and after the diagnosis is finished completely, the ECU controls the carbon tank stop vent valve and the carbon tank electromagnetic valve to restore the original states, and the diagnosis is finished completely.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and improvements can be made without departing from the principle of the present invention, and these modifications and improvements should also be considered as the protection scope of the present invention.
Claims (3)
1. A method for diagnosing fuel leakage of an evaporation system of a fuel vehicle is characterized by comprising the following steps:
1) and (3) carrying out carbon tank flushing calibration:
(1) calibrating the delay time of the carbon tank electromagnetic valve:
under the idle working condition, the delay time calibration of the carbon tank electromagnetic valve adopts a direct calibration method or an indirect calibration method;
(2) calibrating the periodic characteristics of the carbon tank electromagnetic valve:
reducing the delay time of the carbon tank electromagnetic valve, and calibrating the period characteristic of the carbon tank electromagnetic valve as long;
(3) calibrating the activation condition of the carbon tank flushing function:
when the vehicle is in fuel cut and oxygen cleaning, the air-fuel ratio condition is quitted; the water temperature condition meets the preset condition of an evaporation system; presetting an engine starting time counting condition; the pressure of the oil tank has no obvious fluctuation; the voltage is maintained to be normal;
2) and (3) diagnosing and calibrating the leakage of the evaporation system:
(1) the leakage diagnosis of the evaporation system is started, and the following conditions are achieved:
firstly, the water temperature is 4-35 ℃;
the environmental temperature is 4-35 ℃;
③ the engine is started and tnsez is more than 600 s;
setting an idle speed B _ llr, wherein the speed is less than or equal to 3 km/h;
the voltage of the storage battery is 11-16V;
sixthly, the pressure pttp _ w of the oil tank is-25 to 10 hPa;
the ratio pspu of the manifold to the ambient pressure is less than or equal to 0.7;
(8 g) integrating the flushing flow of the carbon canister
(2) An evaporative system leak diagnostic abort comprising one of the following conditions:
firstly, the pressure of the oil tank is continuously reduced beyond a limit value after the vacuumizing is finished;
oil gas is evaporated violently;
thirdly, oil gas is seriously condensed;
fourthly, the actual washing amount has overlarge deviation with the target;
after the carbon canister is closed and flushed, the pressure of the oil tank is not stable for a long time;
(3) judging the diagnosis end condition of the evaporation system:
the first stage is as follows: closing a carbon tank stop vent valve, opening a carbon tank electromagnetic valve, and increasing the vacuum degree of an evaporation system due to the vacuum degree of an air inlet manifold; if the vacuum degree of the evaporation system is not increased, the system detects a coarse leakage fault and the diagnosis is stopped;
and a second stage: when the evaporation system reaches the required vacuum degree, the carbon tank electromagnetic valve is closed, the carbon tank electromagnetic valve and the carbon tank stop ventilation valve are both closed, the vacuum degree of the evaporation system is degraded due to leakage, and the 1mm leakage of the evaporation system is detected according to the degradation gradient;
and a third stage: and after the fuel leakage diagnosis of the evaporation system is finished, the carbon tank stop ventilation valve is opened and keeps a normally open state, and the carbon tank electromagnetic valve is closed.
2. The method as claimed in claim 1, wherein said direct calibration method comprises the steps of:
1) setting the minimum duty ratio opening of the carbon tank electromagnetic valve, wherein the carbon tank electromagnetic valve is in a closed state due to the existence of delay time;
2) and gradually adjusting the duty ratio opening of the electromagnetic valve until the value of the flow sensor changes, and determining the delay time of the carbon tank electromagnetic valve.
3. The method as claimed in claim 1, wherein said indirect calibration method comprises the steps of:
1) setting the frequency of the carbon tank electromagnetic valve, and gradually opening the carbon tank electromagnetic valve;
2) and gradually adjusting the duty ratio opening of the electromagnetic valve until the value of the flow sensor changes, at the moment, offsetting the output duty ratio and the delay time, and calculating the delay time.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210453301.4A CN115111091B (en) | 2022-04-27 | 2022-04-27 | Fuel oil leakage diagnosis method for fuel oil vehicle evaporation system |
Applications Claiming Priority (1)
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