CN115163267B - DOC diagnosis method and aftertreatment system - Google Patents
DOC diagnosis method and aftertreatment system Download PDFInfo
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- CN115163267B CN115163267B CN202211034325.2A CN202211034325A CN115163267B CN 115163267 B CN115163267 B CN 115163267B CN 202211034325 A CN202211034325 A CN 202211034325A CN 115163267 B CN115163267 B CN 115163267B
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- 238000000034 method Methods 0.000 title claims abstract description 31
- 238000003745 diagnosis Methods 0.000 title claims abstract description 22
- 206010021198 ichthyosis Diseases 0.000 title claims abstract 52
- 238000006243 chemical reaction Methods 0.000 claims abstract description 172
- 230000002159 abnormal effect Effects 0.000 claims abstract description 23
- 230000008929 regeneration Effects 0.000 claims abstract description 11
- 238000011069 regeneration method Methods 0.000 claims abstract description 11
- 230000032683 aging Effects 0.000 claims abstract description 8
- 238000002347 injection Methods 0.000 claims description 88
- 239000007924 injection Substances 0.000 claims description 88
- 238000002405 diagnostic procedure Methods 0.000 claims description 12
- 239000007921 spray Substances 0.000 claims description 6
- 238000005507 spraying Methods 0.000 claims description 6
- 230000005856 abnormality Effects 0.000 abstract description 6
- 238000011144 upstream manufacturing Methods 0.000 description 28
- 238000002474 experimental method Methods 0.000 description 10
- 239000000446 fuel Substances 0.000 description 5
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 4
- 231100000572 poisoning Toxicity 0.000 description 4
- 230000000607 poisoning effect Effects 0.000 description 4
- 230000008569 process Effects 0.000 description 4
- 229910052717 sulfur Inorganic materials 0.000 description 4
- 239000011593 sulfur Substances 0.000 description 4
- 239000003054 catalyst Substances 0.000 description 2
- 238000002485 combustion reaction Methods 0.000 description 2
- 239000005416 organic matter Substances 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 230000008707 rearrangement Effects 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N11/00—Monitoring or diagnostic devices for exhaust-gas treatment apparatus, e.g. for catalytic activity
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
- F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
- F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
- F01N3/18—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control
- F01N3/20—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control specially adapted for catalytic conversion ; Methods of operation or control of catalytic converters
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N2550/00—Monitoring or diagnosing the deterioration of exhaust systems
- F01N2550/02—Catalytic activity of catalytic converters
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N2900/00—Details of electrical control or of the monitoring of the exhaust gas treating apparatus
- F01N2900/06—Parameters used for exhaust control or diagnosing
- F01N2900/16—Parameters used for exhaust control or diagnosing said parameters being related to the exhaust apparatus, e.g. particulate filter or catalyst
- F01N2900/1621—Catalyst conversion efficiency
-
- 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)
- Chemical Kinetics & Catalysis (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Health & Medical Sciences (AREA)
- Toxicology (AREA)
- Exhaust Gas After Treatment (AREA)
Abstract
The invention discloses a DOC diagnosis method and a post-treatment system, wherein the DOC diagnosis method comprises the following steps: calculating a first HC conversion efficiency of the DOC after the DPF enters the passive regeneration and the DOC works for a first duration; judging whether the HC conversion efficiency of the DOC is abnormal according to the first HC conversion efficiency; if the HC conversion efficiency of the DOC is abnormal, the DOC enters a first thermal management mode, and the second HC conversion efficiency is calculated; judging whether the HC attached to the surface of the DOC is excessive or not according to the second HC conversion efficiency; if the HC attached to the surface of the DOC is not excessive, the DOC enters a second thermal management mode, and third HC conversion efficiency is calculated; and judging whether SOF attached to the surface of the DOC is excessive or not according to the third HC conversion efficiency, and judging whether the DOC is aged or not. The abnormality of the HC conversion efficiency of the DOC can be diagnosed as any one of an attached HC excess on the DOC surface, an SOF excess attached on the DOC surface, and DOC aging.
Description
Technical Field
The invention relates to the technical field of vehicle aftertreatment, in particular to a DOC diagnosis method and a DOC aftertreatment system.
Background
Currently, due to emissions regulations, it is desirable to add an aftertreatment system to an engine system and convert engine exhaust through a supported catalyst within the aftertreatment system. Among them, the aftertreatment system mainly consists of DOC (Diesel Oxidation Catalyst ) and DPF (Diesel Particulate Filter, diesel particulate filter), so DOC is one of the important components in the aftertreatment system, and its working performance directly affects the working performance of the DPF.
Among these, there are multiple factors that lead to the failure of the DOC to operate, such as: the excessive HC attached to the surface of the DOC, whether the excessive SOF (Soluble Organic Fraction, soluble organic matter) attached to the surface of the DOC causes sulfur poisoning, DOC aging and the like, and especially when the vehicle operates in a low-temperature environment, the low temperature can cause the increased HC attached to the surface of the DOC and can exacerbate the sulfur poisoning of the DOC. However, the DOC diagnosing method in the prior art can only be used for diagnosing whether the DOC is sulfur-poisoned or not, but cannot diagnose other factors causing bad working performance of the DOC, and has poor reliability.
Disclosure of Invention
The invention aims to provide a DOC diagnosis method and a post-treatment system, which are used for solving the problems that other factors causing bad working performance of DOC cannot be diagnosed by the DOC diagnosis method in the prior art and the reliability is poor.
To achieve the purpose, the invention adopts the following technical scheme:
a DOC diagnostic method, comprising:
after the DPF enters passive regeneration, calculating a first HC conversion efficiency after the DOC works for a first duration;
judging whether the HC conversion efficiency of the DOC is abnormal according to the first HC conversion efficiency;
if the HC conversion efficiency of the DOC is abnormal, the DOC enters a first thermal management mode, and the second HC conversion efficiency of the DOC after the first thermal management mode is calculated;
judging whether the HC attached to the surface of the DOC is excessive or not according to the second HC conversion efficiency;
if the HC attached to the surface of the DOC is not excessive, the DOC enters a second thermal management mode, and third HC conversion efficiency of the DOC after the second thermal management mode is calculated;
judging whether SOF attached to the surface of the DOC is excessive or not according to the third HC conversion efficiency, and judging whether the DOC is aged or not.
Preferably, the specific steps of entering the DOC into the first thermal management mode and calculating the second HC conversion efficiency of the DOC after the first thermal management mode include:
the temperature of the DOC is a first set temperature and lasts for a second duration by adjusting the opening degree of the throttle valve and/or the oil injection quantity of the aftertreatment system;
controlling the aftertreatment system to spray oil for the first time, and recording the first oil spraying duration;
calculating a first HC injection quantity in the first injection duration;
judging whether the first HC injection quantity is larger than or equal to a first set HC injection quantity;
and if the first HC injection quantity is larger than or equal to a first set HC injection quantity, calculating the second HC conversion efficiency.
Preferably, the first set temperature is 300 ℃.
Preferably, the specific steps of entering the DOC into the second thermal management mode and calculating the third HC conversion efficiency of the DOC after the second thermal management mode include:
adjusting the temperature of the DOC to be a second set temperature by adjusting the opening of a throttle valve and/or the oil injection quantity of an aftertreatment system, and continuing for a third duration;
controlling the aftertreatment system to spray oil for the second time, and recording the second oil spraying duration;
calculating a second HC injection quantity in the second injection duration;
judging whether the second HC injection quantity is larger than or equal to a second set HC injection quantity;
and if the second HC injection quantity is greater than or equal to a second set HC injection quantity, calculating the third HC conversion efficiency.
Preferably, the second set temperature is 600 ℃.
Preferably, the specific step of determining whether the HC conversion efficiency of the DOC is abnormal according to the first HC conversion efficiency includes:
judging whether the first HC conversion efficiency is greater than or equal to a first set HC conversion efficiency;
if the first HC conversion efficiency is greater than or equal to the first set HC conversion efficiency, the HC conversion efficiency of the DOC is normal;
if the first HC conversion efficiency is smaller than the first set HC conversion efficiency, the HC conversion efficiency of the DOC is abnormal.
Preferably, the specific step of determining whether the HC coverage amount of the DOC surface is excessive according to the second HC conversion efficiency includes:
judging whether the second HC conversion efficiency is greater than or equal to a second set HC conversion efficiency;
if the second HC conversion efficiency is greater than or equal to the second set HC conversion efficiency, the HC attached to the surface of the DOC is excessive;
and if the first HC conversion efficiency is smaller than the first set HC conversion efficiency, the HC attached to the surface of the DOC is not excessive.
Preferably, the specific steps of judging whether the SOF attached to the surface of the DOC is excessive or not according to the third HC conversion efficiency, and judging whether the DOC is aged or not include:
judging whether the third HC conversion efficiency is greater than or equal to a third set HC conversion efficiency;
if the third HC conversion efficiency is greater than or equal to the third set HC conversion efficiency, the SOF attached to the surface of the DOC is excessive;
and if the first HC conversion efficiency is smaller than the first set HC conversion efficiency, aging the DOC.
Preferably, the first set HC conversion efficiency is equal to or less than the second set HC conversion efficiency is equal to or less than the third set HC conversion efficiency.
An aftertreatment system for implementing the DOC diagnostic method described above.
The invention has the beneficial effects that:
the invention aims to provide a DOC diagnosis method and a post-treatment system, wherein the DOC diagnosis method comprises the following steps: the DPF continuously lasts for a first duration after entering passive regeneration, and the first HC conversion efficiency of the DOC is calculated; judging whether the HC conversion efficiency of the DOC is abnormal according to the first HC conversion efficiency; if the HC conversion efficiency of the DOC is abnormal, the DOC enters a first thermal management mode, the DOC is heated and kept at the temperature after the first thermal management mode, so that the temperature of the DOC is enough to convert the HC on the surface of the DOC, and then the second HC conversion efficiency of the DOC after the first thermal management mode is calculated; judging whether the HC coverage amount of the DOC surface is excessive according to the second HC conversion efficiency, wherein if the second HC conversion efficiency is improved, the excessive HC attached to the DOC surface is indicated; if the HC coverage amount of the surface of the DOC is not excessive, the DOC enters a second thermal management mode, the DOC is heated and insulated again after the second thermal management mode, so that the temperature of the DOC is enough to pyrolyze SOFs attached to the surface of the DOC, and then the third HC conversion efficiency of the DOC after the second thermal management mode is calculated; judging whether the SOF attached to the surface of the DOC is excessive or not according to the third HC conversion efficiency, and judging whether the DOC is aged or not, wherein if the third HC conversion efficiency is improved, the SOF attached to the surface of the DOC is excessive, and if not, the DOC is aged. Therefore, the DOC diagnosis method can diagnose whether the HC conversion efficiency of the DOC is abnormal or not, if the HC conversion efficiency of the DOC is abnormal, the DOC diagnosis method can diagnose that the cause of the HC conversion efficiency abnormality of the DOC is caused by any one of excessive adhering HC on the surface of the DOC, excessive SOF adhering on the surface of the DOC and aging of the DOC, so that the DOC can be managed or replaced accurately, and the reliability is high.
Drawings
FIG. 1 is a flow chart of a DOC diagnostic method provided by an embodiment of the present invention.
Detailed Description
The invention is described in further detail below with reference to the drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting thereof. It should be further noted that, for convenience of description, only some, but not all of the structures related to the present invention are shown in the drawings.
In the description of the present invention, unless explicitly stated and limited otherwise, the terms "connected," "connected," and "fixed" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communicated with the inside of two elements or the interaction relationship of the two elements. The specific meaning of the above terms in the present invention will be understood in specific cases by those of ordinary skill in the art.
In the present invention, unless expressly stated or limited otherwise, a first feature "above" or "below" a second feature may include both the first and second features being in direct contact, as well as the first and second features not being in direct contact but being in contact with each other through additional features therebetween. Moreover, a first feature being "above," "over" and "on" a second feature includes the first feature being directly above and obliquely above the second feature, or simply indicating that the first feature is higher in level than the second feature. The first feature being "under", "below" and "beneath" the second feature includes the first feature being directly under and obliquely below the second feature, or simply means that the first feature is less level than the second feature.
In the description of the present embodiment, the terms "upper", "lower", "right", etc. orientation or positional relationship are based on the orientation or positional relationship shown in the drawings, and are merely for convenience of description and simplicity of operation, and do not indicate or imply that the apparatus or elements referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the invention. Furthermore, the terms "first," "second," and the like, are used merely for distinguishing between descriptions and not for distinguishing between them.
DOC is one of the important components in aftertreatment systems, whose operating performance directly affects the operating performance of the DPF. Among these, there are multiple factors that lead to the failure of the DOC to operate, such as: the excessive HC attached to the surface of the DOC, whether the excessive SOF (Soluble Organic Fraction, soluble organic matter) attached to the surface of the DOC causes sulfur poisoning, DOC aging and the like, and especially when the vehicle operates in a low-temperature environment, the HC attached to the surface of the DOC is increased due to the low temperature, and the DOC sulfur poisoning is aggravated. However, the DOC diagnosing method in the prior art can only be used for diagnosing whether the DOC is sulfur-poisoned or not, but cannot diagnose other factors causing bad working performance of the DOC, and has poor reliability.
Therefore, the DOC diagnosis method is used for diagnosing the working performance of the DOC in the aftertreatment system, can diagnose whether the HC conversion efficiency of the DOC is abnormal or not through the DOC diagnosis method, if the HC conversion efficiency of the DOC is abnormal, the DOC diagnosis method can diagnose that the cause of the HC conversion efficiency abnormality of the DOC is caused by any one of excessive HC attached to the surface of the DOC, excessive SOF attached to the surface of the DOC and aging of the DOC, so that the DOC can be managed or replaced accurately, and the DOC diagnosis method is high in reliability.
As shown in fig. 1, the DOC diagnosis method includes:
s100, judging whether the DPF is in a passive regeneration working state.
If the DPF is in the passive regeneration operation state, step S200 is performed.
If the DPF is not in the passive regeneration operation state, the step S110 is performed.
S110, triggering the DPF to perform passive regeneration. After the DPF has entered passive regeneration, step S200 is performed.
And S200, after the DPF enters passive regeneration, calculating the first HC conversion efficiency after the DOC works for a first duration.
The temperature of the DOC is increased by continuously maintaining the first duration after the DPF enters the passive regeneration, so that the calculated value of the first HC conversion efficiency is ensured to be effective. It will be appreciated that the value of the first duration is large enough that the temperature of the DOC rises to the normal operating temperature. Wherein the first duration is an empirical value obtained by a plurality of experiments in the prior period.
Specifically, an upstream temperature sensor is arranged at the upstream of the DOC, and a downstream temperature sensor is arranged at the downstream of the DOC.
Further specifically, a first upstream temperature value is measured by an upstream temperature sensor of the DOC, a first downstream temperature value is measured by a downstream temperature sensor of the DOC, and a first HC conversion efficiency is calculated from the first upstream temperature value and the first downstream temperature value.
Further specifically, the formula for calculating the first HC conversion efficiency from the first upstream temperature value and the first downstream temperature value is:
wherein T is 11 Is a first upstream temperature value, DEG C; t (T) 12 Is a first downstream temperature value, DEG C; t (T) 13 Is a first upstream theoretical temperature value, DEG C; t (T) 14 Is the first downstream theoretical temperature value, c. When the first HC conversion efficiency is calculated, the integrated time period is a first set time period after the first duration.
The first upstream theoretical temperature value and the first downstream theoretical temperature value are calculated by the theoretical oil injection quantity of the aftertreatment system. The first set period is an empirical value obtained by a large number of experiments in the early stage.
The method for calculating the first upstream theoretical temperature value and the first downstream theoretical temperature value by the theoretical oil injection amount of the aftertreatment system belongs to the prior art, and is not described herein.
S300, judging whether the HC conversion efficiency of the DOC is abnormal according to the first HC conversion efficiency.
Specifically, the specific step of judging whether the HC conversion efficiency of the DOC is abnormal according to the first HC conversion efficiency includes:
and judging whether the first HC conversion efficiency is greater than or equal to the first set HC conversion efficiency.
If the first HC conversion efficiency is greater than or equal to the first set HC conversion efficiency, the HC conversion efficiency of the DOC is normal.
If the first HC conversion efficiency is less than the first set HC conversion efficiency, the HC conversion efficiency of the DOC is abnormal. Step S400 is performed.
Thus, whether the HC conversion efficiency of the DOC is abnormal or not is primarily diagnosed by the first set HC conversion efficiency. It is understood that if the HC conversion efficiency of the DOC is normal, the DOC diagnostic method is ended and the DOC operates normally.
Wherein the first set HC conversion efficiency is an empirical value obtained by a large number of experiments in the early stage.
S400, the DOC enters a first thermal management mode, and the second HC conversion efficiency of the DOC after the first thermal management mode is calculated.
Specifically, the specific steps of entering the DOC into the first thermal management mode and calculating the second HC conversion efficiency of the DOC after the first thermal management mode include:
s410, adjusting the opening degree of the throttle valve and/or the oil injection quantity of the aftertreatment system to enable the temperature of the DOC to be the first set temperature and to last for a second duration.
The opening degree of the throttle valve and the oil injection quantity of the post-treatment system are empirical values obtained through a large number of experiments in the earlier stage. The temperature of the DOC can be ensured to rise to the first set temperature.
Wherein the first set temperature is 300 ℃. Specifically, if the HC attached to the surface of the DOC is excessive, after the temperature of the DOC reaches the first set temperature, the first set temperature is sufficient for conversion so that the HC attached to the surface of the DOC is converted.
The temperature of the DOC is set to be the first set temperature and then is kept for a second duration, so that the temperature of the DOC is kept at 300 ℃ to ensure that the value of the second HC conversion efficiency obtained by subsequent calculation is effective.
Wherein the second duration is an empirical value obtained by a plurality of experiments in the prior period. In this embodiment, the second duration is 1 hour.
S420, controlling the aftertreatment system to spray oil for the first time, and recording the first oil spraying duration.
The temperature of the DOC is made to be the first set temperature by adjusting the oil injection quantity of the aftertreatment system, and the first oil injection is the post injection oil injection of the engine. The post injection of the engine refers to the injection of precisely metered fuel into the combustion chamber within 120-180 deg.c of the crank angle after exhaust top dead center after the main injection. The main injection refers to the process of injecting fuel into the cylinder during normal operation of the engine.
S430, calculating a first HC injection quantity in the first injection duration.
S440, judging whether the first HC injection quantity is larger than or equal to the first set HC injection quantity.
If the first HC injection quantity is greater than or equal to the first set HC injection quantity, then a second HC conversion efficiency is calculated.
It is to be understood that if the first HC injection amount is smaller than the first set HC injection amount, the first injection is continued until the first HC injection amount is equal to or larger than the first set HC injection amount.
Specifically, if the first HC injection amount in the injection amount of the first injection is greater than or equal to the first set HC injection amount, a significant temperature difference exists between the upstream temperature and the downstream temperature of the DOC in the process of converting the first HC injection amount, so as to ensure that the value of the calculated second HC conversion efficiency is effective.
Further specifically, a second upstream temperature value is measured by an upstream temperature sensor of the DOC, a second downstream temperature value is measured by a downstream temperature sensor of the DOC, and a second HC conversion efficiency is calculated from the second upstream temperature value and the second downstream temperature value.
Further specifically, the formula for calculating the second HC conversion efficiency from the second upstream temperature value and the second downstream temperature value is:
wherein T is 21 Is a second upstream temperature value, DEG C; t (T) 22 Is a second downstream temperature value, DEG C; t (T) 23 Is a second upstream theoretical temperature value, DEG C; t (T) 24 Is the second downstream theoretical temperature value, c. And when the second HC conversion efficiency is calculated, the integral time period is a second set time length after the first oil injection is finished.
The second upstream theoretical temperature value and the second downstream theoretical temperature value are both calculated by the theoretical oil injection quantity of the aftertreatment system. The second set period is an empirical value obtained by a large number of experiments in the early stage.
The method for calculating the second upstream theoretical temperature value and the second downstream theoretical temperature value by using the theoretical oil injection amount of the aftertreatment system belongs to the prior art, and is not described herein.
In this embodiment, steps S420 to S440 may be performed simultaneously or sequentially.
S500, judging whether the HC attached to the surface of the DOC is excessive or not according to the second HC conversion efficiency.
Specifically, the specific step of judging whether the HC attached to the DOC surface is excessive or not according to the second HC conversion efficiency includes:
and judging whether the second HC conversion efficiency is greater than or equal to the second set HC conversion efficiency.
If the second HC conversion efficiency is equal to or greater than the second set HC conversion efficiency, the HC adhering to the DOC surface is excessive. The DOC diagnostic method is terminated, and it is determined that the cause of the abnormality in HC conversion efficiency of the DOC is excessive HC adhering to the DOC surface.
If the first HC conversion efficiency is smaller than the first set HC conversion efficiency, the HC adhering to the surface of the DOC is not excessive. Step S600 is performed.
Wherein the second set HC conversion efficiency is an empirical value obtained by a large number of experiments in the early stage.
S600, the DOC enters a second thermal management mode, and the third HC conversion efficiency of the DOC after the second thermal management mode is calculated.
Specifically, the specific steps of entering the second thermal management mode by the DOC and calculating the third HC conversion efficiency of the DOC after the second thermal management mode include:
and S610, adjusting the temperature of the DOC to be a second set temperature by adjusting the opening of the throttle valve and/or the oil injection quantity of the aftertreatment system, and continuing the third duration.
The opening degree of the throttle valve and the oil injection quantity of the post-treatment system are empirical values obtained through a large number of experiments in the earlier stage. The temperature of the DOC can be ensured to rise to the second set temperature.
Wherein the second set temperature is 600 ℃. Specifically, if the DOC surface is excessively adhered with SOF, after the temperature of the DOC reaches the second set temperature, the second set temperature is enough for conversion so that the DOC surface is adhered with SOF.
And setting the temperature of the DOC to be the second set temperature and then continuously maintaining the temperature for a third duration time, so that the temperature of the DOC is continuously at 600 ℃, and the value of the third HC conversion efficiency obtained by subsequent calculation is ensured to be effective.
Wherein the third duration is an empirical value obtained by a plurality of experiments in the earlier stage. In this embodiment, the third duration is 1 hour.
S620, controlling the aftertreatment system to spray oil for the second time, and recording the second oil spraying duration.
The temperature of the DOC is made to be the second set temperature by adjusting the oil injection quantity of the aftertreatment system, and the second oil injection is the post injection oil injection of the engine. The post injection of the engine refers to the injection of precisely metered fuel into the combustion chamber within 120-180 deg.c of the crank angle after exhaust top dead center after the main injection. The main injection refers to the process of injecting fuel into the cylinder during normal operation of the engine.
S630, calculating a second HC injection quantity in a second injection duration.
S640, judging whether the second HC injection quantity is larger than or equal to the second set HC injection quantity.
If the second HC injection quantity is greater than or equal to the second set HC injection quantity, a third HC conversion efficiency is calculated.
It is to be understood that if the second HC injection amount is smaller than the second set HC injection amount, the second injection is continued until the second HC injection amount is equal to or larger than the second set HC injection amount.
Specifically, if the second HC injection amount in the injection amount of the second injection is greater than or equal to the second set HC injection amount, a significant temperature difference exists between the upstream temperature and the downstream temperature of the DOC in the process of converting the second HC injection amount, so as to ensure that the value of the third HC conversion efficiency obtained by calculation is effective.
Further specifically, a third upstream temperature value is measured by an upstream temperature sensor of the DOC, a third downstream temperature value is measured by a downstream temperature sensor of the DOC, and a third HC conversion efficiency is calculated from the third upstream temperature value and the third downstream temperature value.
Further specifically, the formula for calculating the third HC conversion efficiency from the third upstream temperature value and the third downstream temperature value is:
wherein T is 31 Is a third upstream temperature value, DEG C; t (T) 32 Is a third downstream temperature value, DEG C; t (T) 33 Is a third upstream theoretical temperature value, DEG C; t (T) 34 Is the third downstream theoretical temperature value, c. And when the third HC conversion efficiency is calculated, the integral time period is a third set time length after the second fuel injection is finished.
The third upstream theoretical temperature value and the third downstream theoretical temperature value are calculated by the theoretical oil injection quantity of the aftertreatment system. The third set period is an empirical value obtained by a large number of experiments in the early stage.
The method for calculating the third upstream theoretical temperature value and the third downstream theoretical temperature value by using the theoretical oil injection amount of the aftertreatment system belongs to the prior art, and is not described herein.
In this embodiment, steps S620 to S640 may be performed simultaneously or sequentially.
And S700, judging whether SOF attached to the surface of the DOC is excessive or not according to the third HC conversion efficiency, and judging whether the DOC is aged or not.
Specifically, the specific steps of judging whether the SOF attached to the DOC surface is excessive or not and judging whether the DOC is aged or not according to the third HC conversion efficiency include:
and judging whether the third HC conversion efficiency is greater than or equal to the third set HC conversion efficiency.
If the third HC conversion efficiency is equal to or greater than the third set HC conversion efficiency, the SOF attached to the DOC surface is excessive.
If the first HC conversion efficiency is less than the first set HC conversion efficiency, the DOC ages.
Therefore, the DOC diagnosis method can diagnose whether the HC conversion efficiency of the DOC is abnormal or not, if the HC conversion efficiency of the DOC is abnormal, the DOC diagnosis method can diagnose that the cause of the HC conversion efficiency abnormality of the DOC is caused by any one of excessive adhering HC on the surface of the DOC, excessive SOF adhering on the surface of the DOC and aging of the DOC, so that the DOC can be managed or replaced accurately, and the reliability is high.
Wherein the first set HC conversion efficiency is less than or equal to the second set HC conversion efficiency is less than or equal to the third set HC conversion efficiency. It is appreciated that as the ambient temperature of the DOC increases, the HC conversion efficiency of the DOC increases. Therefore, the values of the first set HC conversion efficiency, the second set HC conversion efficiency and the third set HC conversion efficiency can be adjusted with the environmental temperature adaptability of the DOC.
The invention also provides a post-treatment system, which can diagnose whether the HC conversion efficiency of the DOC is abnormal or not and the cause of the abnormality of the HC conversion efficiency of the DOC by applying the DOC diagnosis method, so that the DOC can be managed or replaced accurately.
It is to be understood that the above examples of the present invention are provided for clarity of illustration only and are not limiting of the embodiments of the present invention. Various obvious changes, rearrangements and substitutions can be made by those skilled in the art without departing from the scope of the invention. It is not necessary here nor is it exhaustive of all embodiments. Any modification, equivalent replacement, improvement, etc. which come within the spirit and principles of the invention are desired to be protected by the following claims.
Claims (10)
1. A method of DOC diagnosis, comprising:
after the DPF enters passive regeneration, calculating a first HC conversion efficiency after the DOC works for a first duration;
judging whether the HC conversion efficiency of the DOC is abnormal according to the first HC conversion efficiency;
if the HC conversion efficiency of the DOC is abnormal, the DOC enters a first thermal management mode, and the second HC conversion efficiency of the DOC after the first thermal management mode is calculated;
judging whether the HC attached to the surface of the DOC is excessive or not according to the second HC conversion efficiency;
if the HC attached to the surface of the DOC is not excessive, the DOC enters a second thermal management mode, and third HC conversion efficiency of the DOC after the second thermal management mode is calculated;
judging whether SOF attached to the surface of the DOC is excessive or not according to the third HC conversion efficiency, and judging whether the DOC is aged or not.
2. The DOC diagnostic method as claimed in claim 1, wherein the specific steps of entering a first thermal management mode and calculating a second HC conversion efficiency of the DOC after the first thermal management mode include:
the temperature of the DOC is a first set temperature and lasts for a second duration by adjusting the opening degree of the throttle valve and/or the oil injection quantity of the aftertreatment system;
controlling the aftertreatment system to spray oil for the first time, and recording the first oil spraying duration;
calculating a first HC injection quantity in the first injection duration;
judging whether the first HC injection quantity is larger than or equal to a first set HC injection quantity;
and if the first HC injection quantity is larger than or equal to a first set HC injection quantity, calculating the second HC conversion efficiency.
3. The DOC diagnostic method as claimed in claim 2, wherein the first set temperature is 300 ℃.
4. The DOC diagnostic method as claimed in claim 1, wherein the specific step of entering a second thermal management mode and calculating a third HC conversion efficiency of the DOC after the second thermal management mode comprises:
adjusting the temperature of the DOC to be a second set temperature by adjusting the opening of a throttle valve and/or the oil injection quantity of an aftertreatment system, and continuing for a third duration;
controlling the aftertreatment system to spray oil for the second time, and recording the second oil spraying duration;
calculating a second HC injection quantity in the second injection duration;
judging whether the second HC injection quantity is larger than or equal to a second set HC injection quantity;
and if the second HC injection quantity is greater than or equal to a second set HC injection quantity, calculating the third HC conversion efficiency.
5. The DOC diagnostic method as claimed in claim 4, wherein the second set temperature is 600 ℃.
6. The DOC diagnosis method according to any one of claims 1 to 5, wherein the specific step of judging whether the HC conversion efficiency of the DOC is abnormal or not in accordance with the first HC conversion efficiency includes:
judging whether the first HC conversion efficiency is greater than or equal to a first set HC conversion efficiency;
if the first HC conversion efficiency is greater than or equal to the first set HC conversion efficiency, the HC conversion efficiency of the DOC is normal;
if the first HC conversion efficiency is smaller than the first set HC conversion efficiency, the HC conversion efficiency of the DOC is abnormal.
7. The DOC diagnostic method according to claim 6, wherein the specific step of determining whether the HC coverage of the DOC surface is excessive in accordance with the second HC conversion efficiency includes:
judging whether the second HC conversion efficiency is greater than or equal to a second set HC conversion efficiency;
if the second HC conversion efficiency is greater than or equal to the second set HC conversion efficiency, the HC attached to the surface of the DOC is excessive;
and if the first HC conversion efficiency is smaller than the first set HC conversion efficiency, the HC attached to the surface of the DOC is not excessive.
8. The DOC diagnosis method according to claim 7, wherein the specific steps of judging whether the SOF attached to the DOC surface is excessive or not, and judging whether the DOC is aged or not, based on the third HC conversion efficiency, include:
judging whether the third HC conversion efficiency is greater than or equal to a third set HC conversion efficiency;
if the third HC conversion efficiency is greater than or equal to the third set HC conversion efficiency, the SOF attached to the surface of the DOC is excessive;
and if the first HC conversion efficiency is smaller than the first set HC conversion efficiency, aging the DOC.
9. The DOC diagnostic method according to claim 8, wherein the first set HC conversion efficiency is equal to or less than the second set HC conversion efficiency is equal to or less than the third set HC conversion efficiency.
10. An aftertreatment system for implementing the DOC diagnostic method defined in any one of claims 1-9.
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