CN110985244A - Method for diagnosing vehicle fuel evaporation coarse leakage - Google Patents
Method for diagnosing vehicle fuel evaporation coarse leakage Download PDFInfo
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- CN110985244A CN110985244A CN201911158463.XA CN201911158463A CN110985244A CN 110985244 A CN110985244 A CN 110985244A CN 201911158463 A CN201911158463 A CN 201911158463A CN 110985244 A CN110985244 A CN 110985244A
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- 230000008020 evaporation Effects 0.000 title claims abstract description 54
- 238000001704 evaporation Methods 0.000 title claims abstract description 54
- 238000000034 method Methods 0.000 title claims abstract description 25
- 239000000446 fuel Substances 0.000 title claims abstract description 18
- 238000003745 diagnosis Methods 0.000 claims abstract description 36
- 238000001514 detection method Methods 0.000 claims abstract description 11
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 20
- 229910052799 carbon Inorganic materials 0.000 claims description 20
- 238000002405 diagnostic procedure Methods 0.000 claims 4
- 230000006855 networking Effects 0.000 abstract 1
- 239000007789 gas Substances 0.000 description 4
- 230000009286 beneficial effect Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000002737 fuel gas Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
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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
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- 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
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- 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
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- 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)
- Examining Or Testing Airtightness (AREA)
Abstract
The invention relates to the technical field of vehicle networking, and provides a vehicle fuel evaporation rough leakage diagnosis method which specifically comprises the following steps: s1, detecting whether the current air pressure compensation gradient of the evaporation system is larger than a preset gradient threshold value or not, and if so, performing coarse leakage detection on the evaporation system; the gradient preset threshold is set based on the ambient temperature and the temperature of the intake manifold. When the temperature of the intake manifold and the ambient temperature are both greater than the temperature threshold, the preset gradient value is set to be a threshold gradient value 2, and when the temperature of the intake manifold or the ambient temperature is less than or equal to the temperature threshold, the preset gradient value is set to be a threshold gradient value 1, and the threshold gradient value 1 is less than the threshold gradient value 2. When the ambient temperature and the intake air temperature of the intake manifold are both greater than the temperature threshold, the threshold of the pressure compensation gradient is properly amplified, and the gradient threshold 2 is adopted, so that the coarse leakage diagnosis frequency of the high-temperature environment is improved.
Description
Technical Field
The invention relates to the technical field of evaporation diagnosis, and provides a diagnosis method for vehicle fuel evaporation coarse leakage.
Background
The state six legislation clearly states that one or more leakage points exist in the whole evaporation system, and when the leakage amount of the leakage points is larger than or equal to the leakage amount generated by the small hole with the diameter of 1mm, the OBD is required to detect the failure of the evaporation system. The diagnosis method for vacuumizing the closed space by utilizing the negative pressure of the manifold is a diagnosis method with higher cost performance, but the diagnosis rate cannot meet the standard aiming at the rough leakage diagnosis of the evaporation system, particularly, the high fuel evaporation rate causes overlarge pressure compensation gradient in a high-temperature environment, and when the pressure compensation gradient of the evaporation system is greater than a preset value, the whole diagnosis process is stopped, so that the rough leakage diagnosis rate in the high-temperature environment is reduced.
Disclosure of Invention
The invention provides a method for diagnosing coarse leakage of vehicle fuel evaporation, and aims to solve the problem of low diagnosis rate of coarse leakage diagnosis of an evaporation system in a high-temperature environment.
The invention is realized in such a way that a vehicle fuel evaporation rough leakage diagnosis method specifically comprises the following steps:
s1, detecting whether the current air pressure compensation gradient of the evaporation system is larger than a preset gradient threshold value or not, and if so, performing coarse leakage detection on the evaporation system;
the gradient preset threshold is set based on the ambient temperature and the temperature of the intake manifold.
Further, when the temperature of the intake manifold and the ambient temperature are both greater than the temperature threshold, the preset gradient value is set to be a threshold gradient value 2, and when the temperature of the intake manifold or the ambient temperature is less than or equal to the temperature threshold, the preset gradient value is set to be a threshold gradient value 1, and the threshold gradient value 1 is less than the threshold gradient value 2.
Further, the method for acquiring the air pressure compensation gradient specifically comprises the following steps:
s11, when the pressure of the oil tank is close to the atmospheric pressure, closing the carbon tank electromagnetic valve and the carbon tank closing valve, and detecting the air pressure value of the evaporation system at the moment;
and S12, detecting the air pressure value II of the evaporation system after the set time length, wherein the ratio of the air pressure difference value to the set time length is the compensation gradient, and the air pressure difference value is the difference value between the air pressure value II and the air pressure value I.
Further, the crude leakage diagnosis method of the evaporation system comprises the following specific steps:
s11, controlling the carbon tank electromagnetic valve to be in an open state, controlling the carbon tank closing valve to be in a closed state, and vacuumizing the evaporation system through the air inlet manifold;
and S12, when the gas flow in the carbon tank reaches the flow threshold, detecting whether the vacuum degree of the evaporation system reaches the vacuum degree threshold, if not, judging that the vacuum system has coarse leakage, and terminating the coarse leakage diagnosis program.
Further, in step S12, if the vacuum degree of the evaporation system reaches the vacuum degree threshold, step S13 is executed;
and S13, closing the electromagnetic valve of the control tank, detecting the air pressure compensation gradient of the vacuum system after setting the time length, and entering fine leakage detection if the air pressure compensation gradient is less than or equal to a gradient threshold value 1.
Further, the coarse leak test is to detect leaks having a diameter of 2mm or more, and the fine leak test is to detect leaks having a diameter of 1mm or more.
Further, the gradient threshold 1 and the gradient threshold 2 are empirical parameters.
The vehicle fuel evaporation rough leakage diagnosis method provided by the invention has the following beneficial technical effects:
1) when the ambient temperature and the air inlet temperature of the air inlet manifold are both greater than the temperature threshold, the threshold of the pressure compensation gradient is properly amplified, and the gradient threshold 2 is adopted, so that the coarse leakage diagnosis frequency of the high-temperature environment is improved;
2) and after the pressure compensation gradient calculation is finished, vacuumizing the closed system, when the gas flow of the carbon tank reaches a certain value, the vacuum degree of the system is very small, indicating that the system has coarse leakage, finishing the coarse leakage diagnosis, and finishing the evaporation leakage diagnosis. If the vacuum degree of the system is established, the system does not have coarse leakage, and the pressure compensation gradient is judged again at the moment. If the pressure compensation gradient is larger than the gradient threshold value 1, the evaporation leakage diagnosis process is also exited, and if the pressure compensation gradient is smaller than the gradient threshold value 1, the fine leakage diagnosis is continued. Therefore, the diagnosis rate of the coarse leakage can be ensured, and the diagnosis result of the fine leakage cannot be influenced.
Drawings
Fig. 1 is a flowchart of a vehicle fuel evaporation rough leak diagnosis method according to an embodiment of the present invention.
Detailed Description
The following description of preferred embodiments of the invention will be made in further detail with reference to the accompanying drawings.
Fig. 1 is a flowchart of a vehicle fuel evaporation rough leak diagnosis method provided by an embodiment of the present invention, which specifically includes the following steps:
s1, detecting whether the current pressure compensation gradient of the evaporation system is larger than a gradient preset threshold value, if so, performing coarse leakage detection on the evaporation system, and if not, terminating the coarse leakage diagnosis program due to overhigh evaporation degree of fuel gas;
in the embodiment of the present invention, the preset gradient threshold is set based on the ambient temperature and the temperature of the intake manifold, for example, when both the temperature of the intake manifold and the ambient temperature are greater than the temperature threshold, the preset gradient threshold is set to be a threshold gradient 2, when the temperature of the intake manifold or the ambient temperature is less than or equal to the temperature threshold, the preset gradient threshold is set to be a threshold gradient 1, the threshold gradient 1 is less than the threshold gradient 2, and both the threshold gradient 1 and the threshold gradient 2 are empirical parameters;
in the embodiment of the present invention, the method for obtaining the pressure compensation gradient specifically includes the following steps:
s11, when the pressure of the oil tank is close to the atmospheric pressure, closing the carbon tank electromagnetic valve and the carbon tank closing valve, and detecting the air pressure value one of the evaporation system at the moment;
in an embodiment of the invention, the intake manifold is communicated with the oil tank through a carbon tank solenoid valve, and the oil tank is communicated with the atmosphere through a carbon tank closing valve.
S12, after a set time (for example, several seconds), detecting a second air pressure value of the evaporation system, wherein the ratio of the air pressure difference value to the set time is a compensation gradient, and the air pressure difference value is the difference between the second air pressure value and the first air pressure value.
In the embodiment of the present invention, the method for diagnosing a rough leak of an evaporation system specifically includes the following steps:
s11, controlling the carbon tank electromagnetic valve to be in an open state, controlling the carbon tank closing valve to be in a closed state, and vacuumizing the evaporation system through the negative pressure of the air inlet manifold;
s12, when the gas flow in the carbon tank reaches the flow threshold, detecting whether the vacuum degree of the evaporation system reaches the vacuum degree threshold, and if so, executing the step S13; if the detection result is negative, judging that the vacuum system has coarse leakage, and terminating the coarse leakage diagnosis program;
s13, controlling the carbon tank electromagnetic valve to close, detecting the pressure compensation gradient of the vacuum system after setting a time length, if the pressure compensation gradient is less than or equal to the gradient threshold value 1, entering fine leakage detection, if the detection result is negative,
in the embodiment of the invention, the coarse leakage detection is to detect the leakage point with the diameter of more than 2mm, and the fine leakage detection is to detect the leakage point with the diameter of more than 1 mm.
The vehicle fuel evaporation rough leakage diagnosis method provided by the invention has the following beneficial technical effects:
1) when the ambient temperature and the air inlet temperature of the air inlet manifold are both greater than the temperature threshold, the threshold of the pressure compensation gradient is properly amplified, and the gradient threshold 2 is adopted, so that the coarse leakage diagnosis frequency of the high-temperature environment is improved;
2) and after the pressure compensation gradient calculation is finished, vacuumizing the closed system, when the gas flow of the carbon tank reaches a certain value, the vacuum degree of the system is very small, indicating that the system has coarse leakage, finishing the coarse leakage diagnosis, and finishing the evaporation leakage diagnosis. If the vacuum degree of the system is established, the system does not have coarse leakage, and the pressure compensation gradient is judged again at the moment. If the pressure compensation gradient is larger than the gradient threshold value 1, the evaporation leakage diagnosis process is also exited, and if the pressure compensation gradient is smaller than the gradient threshold value 1, the fine leakage diagnosis is continued. Therefore, the diagnosis rate of the coarse leakage can be ensured, and the diagnosis result of the fine leakage cannot be influenced.
It is clear that the specific implementation of the invention is not restricted to the above-described embodiments, but that various insubstantial modifications of the inventive process concept and technical solutions are within the scope of protection of the invention.
Claims (7)
1. A vehicle fuel evaporation rough leakage diagnosis method is characterized by comprising the following steps:
s1, detecting whether the current air pressure compensation gradient of the evaporation system is larger than a preset gradient threshold value or not, and if so, performing coarse leakage detection on the evaporation system;
the gradient preset threshold is set based on the ambient temperature and the temperature of the intake manifold.
2. The vehicle fuel evaporation rough leak diagnostic method according to claim 1, characterized in that the gradient preset value is set to a gradient threshold value 2 when both the temperature of the intake manifold and the ambient temperature are greater than the temperature threshold values, and the gradient preset value is set to a gradient threshold value 1 when the temperature of the intake manifold or the ambient temperature is equal to or less than the temperature threshold values, the gradient threshold value 1 being less than the gradient threshold value 2.
3. The vehicle fuel evaporation rough leakage diagnostic method according to claim 1, wherein the method for acquiring the air pressure compensation gradient specifically comprises the following steps:
s11, when the pressure of the oil tank is close to the atmospheric pressure, closing the carbon tank electromagnetic valve and the carbon tank closing valve, and detecting the air pressure value of the evaporation system at the moment;
and S12, detecting the air pressure value II of the evaporation system after the set time length, wherein the ratio of the air pressure difference value to the set time length is the compensation gradient, and the air pressure difference value is the difference value between the air pressure value II and the air pressure value I.
4. The vehicle fuel evaporation rough leak diagnosis method according to claim 1, characterized in that the rough leak diagnosis method of the evaporation system is specifically as follows:
s11, controlling the carbon tank electromagnetic valve to be in an open state, controlling the carbon tank closing valve to be in a closed state, and vacuumizing the evaporation system through the air inlet manifold;
and S12, when the gas flow in the carbon tank reaches the flow threshold, detecting whether the vacuum degree of the evaporation system reaches the vacuum degree threshold, if not, judging that the vacuum system has coarse leakage, and terminating the coarse leakage diagnosis program.
5. The vehicle fuel evaporation rough leak diagnosis method according to claim 4, characterized in that in step S12, if the vacuum degree of the evaporation system reaches the vacuum degree threshold, step S13 is executed;
and S13, closing the electromagnetic valve of the control tank, detecting the air pressure compensation gradient of the vacuum system after setting the time length, and entering fine leakage detection if the air pressure compensation gradient is less than or equal to a gradient threshold value 1.
6. A vehicle fuel evaporation rough leak diagnostic method as set forth in claim 1, wherein the rough leak test is a test for leaks having a diameter of 2mm or more, and the fine leak test is a test for leaks having a diameter of 1mm or more.
7. The vehicle fuel evaporation gross leak diagnostic method according to claim 2, wherein the gradient threshold value 1 and the gradient threshold value 2 are empirical parameters.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201911158463.XA CN110985244B (en) | 2019-11-22 | 2019-11-22 | Method for diagnosing vehicle fuel evaporation coarse leakage |
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| CN201911158463.XA CN110985244B (en) | 2019-11-22 | 2019-11-22 | Method for diagnosing vehicle fuel evaporation coarse leakage |
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| CN110985244A true CN110985244A (en) | 2020-04-10 |
| CN110985244B CN110985244B (en) | 2021-01-05 |
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Citations (8)
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|---|---|---|---|---|
| DE10143327A1 (en) * | 2001-09-05 | 2003-03-20 | Bosch Gmbh Robert | Leak detection system for use in motor vehicle fuel tank ventilation system has improved accuracy and reliability as a temperature compensation factor is applied to compensate for fuel vaporization being temperature dependent |
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| US20150219522A1 (en) * | 2014-02-04 | 2015-08-06 | Ford Global Technologies, Llc | Correlation based fuel tank leak detection |
| US20160069771A1 (en) * | 2014-09-10 | 2016-03-10 | Ford Global Technologies, Llc | System and methods for fuel system leak detection |
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-
2019
- 2019-11-22 CN CN201911158463.XA patent/CN110985244B/en active Active
Patent Citations (8)
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|---|---|---|---|---|
| DE10143327A1 (en) * | 2001-09-05 | 2003-03-20 | Bosch Gmbh Robert | Leak detection system for use in motor vehicle fuel tank ventilation system has improved accuracy and reliability as a temperature compensation factor is applied to compensate for fuel vaporization being temperature dependent |
| CN1573071A (en) * | 2003-05-29 | 2005-02-02 | 日立优喜雅汽车配件有限公司 | Leakage diagnosis apparatus for fuel vapor purge system and method thereof |
| CN1704577A (en) * | 2004-06-01 | 2005-12-07 | 日产自动车株式会社 | Leak detecting device for fuel vapor treatment unit |
| CN102057153A (en) * | 2008-06-05 | 2011-05-11 | 罗伯特.博世有限公司 | Method for detecting leaks in a tank system |
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| US20150219522A1 (en) * | 2014-02-04 | 2015-08-06 | Ford Global Technologies, Llc | Correlation based fuel tank leak detection |
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| CN110985244B (en) | 2021-01-05 |
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