CN115030834B - LNT-based engine control method and device and vehicle - Google Patents
LNT-based engine control method and device and vehicle Download PDFInfo
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- CN115030834B CN115030834B CN202111225492.0A CN202111225492A CN115030834B CN 115030834 B CN115030834 B CN 115030834B CN 202111225492 A CN202111225492 A CN 202111225492A CN 115030834 B CN115030834 B CN 115030834B
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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
- F02D41/30—Controlling fuel injection
- F02D41/38—Controlling fuel injection of the high pressure type
- F02D41/40—Controlling fuel injection of the high pressure type with means for controlling injection timing or duration
- F02D41/402—Multiple injections
- F02D41/405—Multiple injections with post injections
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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
- F02D41/02—Circuit arrangements for generating control signals
- F02D41/021—Introducing corrections for particular conditions exterior to the engine
- F02D41/0235—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus
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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
- F02D41/02—Circuit arrangements for generating control signals
- F02D41/14—Introducing closed-loop corrections
- F02D41/1438—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor
- F02D41/1444—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases
- F02D41/1445—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases the characteristics being related to the exhaust flow
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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
- F02D41/02—Circuit arrangements for generating control signals
- F02D41/14—Introducing closed-loop corrections
- F02D41/1438—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor
- F02D41/1444—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases
- F02D41/146—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases the characteristics being an NOx content or concentration
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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
- F02D41/02—Circuit arrangements for generating control signals
- F02D41/14—Introducing closed-loop corrections
- F02D41/1438—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor
- F02D41/1473—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the regulation method
- F02D41/1475—Regulating the air fuel ratio at a value other than stoichiometry
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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)
- Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
Abstract
The embodiment of the application relates to the technical field of automobiles, in particular to an engine control method and device based on an LNT (low-cost engine), and a vehicle, wherein the control method comprises the following steps: acquiring the current working condition of an engine and an air-fuel ratio chart in real time; determining a target upper limit air-fuel ratio and a target lower limit air-fuel ratio corresponding to when the emission reaches a preset emission under the current working condition based on the air-fuel ratio chart; when the LNT of the vehicle exhaust aftertreatment system is in a DeNOx state, acquiring the current air-fuel ratio of the engine; when the current air-fuel ratio is not between the target upper limit air-fuel ratio and the target lower limit air-fuel ratio, the post-injection amount of the engine in the DeNOx state is controlled to control the current air-fuel ratio to be between the target upper limit air-fuel ratio and the target lower limit air-fuel ratio. The propylene emission of the LNT can be reduced by adjusting the post-injection quantity of the engine, the effect of improving the tail gas treatment effect of the LNT is achieved, the formula of the catalyst in the LNT does not need to be replaced, and the development cost of the LNT is effectively reduced.
Description
Technical Field
The embodiment of the application relates to the technical field of automobiles, in particular to an engine control method and device based on an LNT and a vehicle.
Background
Three reducing gases (CO, propylene and H2) are generated in the thick combustion process of the engine, so that the efficient reduction performance of the H2 and the CO can be fully exerted, and the influence of the propylene is avoided, which is a key problem in engineering application of the LNT.
In the related art, a catalyst in the LNT is generally replaced with a dedicated catalyst to reduce the effect of propylene, but switching the catalyst formulation may result in an increase in the development cost of the LNT, which is less applicable.
Disclosure of Invention
The embodiment of the application provides an engine control method, an engine control device and a vehicle based on an LNT (Low-Density transistor), aiming at solving the problem that the development cost of the LNT is increased due to the fact that a catalyst formula is switched.
A first aspect of an embodiment of the present application provides an engine control method based on an LNT, which is characterized in that,
the control method comprises the following steps:
acquiring an air-fuel ratio chart and working parameters of a current engine;
acquiring a target upper limit air-fuel ratio and a target lower limit air-fuel ratio according to the current working parameters and an air-fuel ratio chart;
wherein the air-fuel ratio chart comprises combinations of different working parameters of the engine, and when the emission reaches a preset emission, the corresponding upper limit air-fuel ratio and lower limit air-fuel ratio are adopted;
acquiring a current air-fuel ratio of the engine when the vehicle exhaust aftertreatment system is in a DeNOx state;
when the DeNOx state is set and the current air-fuel ratio is not between the target upper limit air-fuel ratio and the target lower limit air-fuel ratio, an adjustment mode of the engine is activated, and the post-injection amount of the engine in the DeNOx state is adjusted so that the current air-fuel ratio is between the target upper limit air-fuel ratio and the target lower limit air-fuel ratio.
Alternatively, the process may be carried out in a single-stage,
acquiring the air-fuel ratio map, including:
selecting test points of the working parameters and the air-fuel ratio;
and scanning the test points to generate the air-fuel ratio chart.
Alternatively, the process may be carried out in a single-stage,
selecting test points of the working parameters and the air-fuel ratio, wherein the test points comprise:
selecting different working parameters, defining preset selection intervals in respective preset test ranges, and determining a plurality of different first test points;
and selecting the air-fuel ratio, defining a preset selecting interval in a preset testing range, and determining a plurality of different second testing points.
Alternatively, the process may be carried out in a single-stage,
sweeping the test point to generate the air-fuel ratio chart, including:
according to the first test point and the second test point, acquiring the emission amount of propylene in the engine;
determining the lower limit air-fuel ratio and the upper limit air-fuel ratio according to the emission amount;
the air-fuel ratio map is generated based on the lower limit air-fuel ratio, the upper limit air-fuel ratio, and the first test point.
Alternatively, the process may be carried out in a single-stage,
activating an adjustment mode of the engine when the DeNOx state is set and the current air-fuel ratio is not between a target upper limit air-fuel ratio and a target lower limit air-fuel ratio, adjusting a post injection amount of the engine in the DeNOx state, comprising:
activating an adjustment mode of the engine and acquiring a difference between the current air-fuel ratio and the target lower limit air-fuel ratio when it is detected that the current air-fuel ratio is less than or equal to the target lower limit air-fuel ratio;
in the adjustment mode, the post injection amount of the engine in the DeNOx state is determined to be reduced according to the difference value so as to improve the current air-fuel ratio.
Alternatively, the process may be carried out in a single-stage,
activating an adjustment mode of the engine when the DeNOx state is set and the current air-fuel ratio is not between a target upper limit air-fuel ratio and a target lower limit air-fuel ratio, adjusting a post injection amount of the engine in the DeNOx state, comprising:
activating an adjustment mode of the engine and acquiring a difference between the current air-fuel ratio and the target lower limit air-fuel ratio when it is detected that the current air-fuel ratio is greater than the target lower limit air-fuel ratio;
and in the adjustment mode, determining to increase the post injection quantity of the engine in the DeNOx state according to the difference value so as to increase the current air-fuel ratio.
Optionally, the method is characterized in that,
the operating parameters include engine power, main fuel injection quantity, engine speed and engine torque.
A second aspect of an embodiment of the present application provides an engine control apparatus based on an LNT, the control apparatus including:
the detection module is used for acquiring an air-fuel ratio chart and the current working parameters of the engine;
a determining module for
Acquiring a target upper limit air-fuel ratio and a target lower limit air-fuel ratio according to the current working parameters and an air-fuel ratio chart;
wherein the air-fuel ratio chart comprises combinations of different working parameters of the engine, and when the emission reaches a preset emission, the corresponding upper limit air-fuel ratio and lower limit air-fuel ratio are adopted;
the acquisition module is used for acquiring the current air-fuel ratio of the engine when the LNT of the vehicle exhaust aftertreatment system is in a DeNOx state;
an adjustment module configured to activate an adjustment mode of the engine when the current air-fuel ratio is not between a target upper limit air-fuel ratio and a target lower limit air-fuel ratio, and control the engine to adjust a post-injection amount in the DeNOx state so that the current air-fuel ratio is between the target upper limit air-fuel ratio and the target lower limit air-fuel ratio.
Optionally, the control device further includes:
and the chart acquisition module is used for acquiring the air-fuel ratio chart.
A third aspect of the embodiment of the present application provides a vehicle, including the above-mentioned control device, so as to implement the above-mentioned control method.
According to the LNT-based engine control method, the LNT-based engine control device and the vehicle, in the running process of the vehicle, the current working condition of the engine and the air-fuel ratio chart of the engine are obtained, the target upper limit air-fuel ratio and the target lower limit air-fuel ratio corresponding to the current working condition in the air-fuel ratio chart are obtained according to the current working condition and the air-fuel ratio chart, namely, when the propylene emission amount under the current working condition reaches the preset emission amount, the upper limit value and the lower limit value of the air-fuel ratio are obtained, when the LNT of the vehicle exhaust aftertreatment system is in a DeNOx state, the current air-fuel ratio of the engine is obtained, the current air-fuel ratio of the engine is compared with the target upper limit air-fuel ratio and the target lower limit air-fuel ratio, when the air-fuel ratio is not between the target upper limit air-fuel ratio and the target lower limit air-fuel ratio, the propylene emission amount of the LNT is considered to reach the preset emission amount, namely, the LNT is controlled to be in the state of high propylene emission amount under the DeNOx state, the current air-fuel ratio is controlled, the propylene emission amount of the LNT is accordingly, the exhaust treatment effect of the LNT is improved, the propylene emission amount of the LNT is reduced, the exhaust emission amount of the vehicle exhaust treatment system is adjusted, the LNT is improved, the LNT has no cost has been changed, and the LNT catalyst has no cost.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the description of the embodiments of the present application will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a flow chart of a control method according to an embodiment of the present application;
FIG. 2 is a flow chart of an air-fuel ratio map according to an embodiment of the present application;
FIG. 3 is a flow chart illustrating the selection of the working parameters and the test points according to an embodiment of the present application;
FIG. 4 is a flow chart illustrating the generation of an air-fuel ratio map according to an embodiment of the present application;
FIG. 5A is a chart illustrating a lower limit air-fuel ratio according to an embodiment of the present application;
FIG. 5B is a graph showing an upper limit air-fuel ratio according to an embodiment of the present application;
FIG. 6A is a chart showing a lower limit air-fuel ratio according to another embodiment of the present application;
fig. 6B is a graph of an upper limit air-fuel ratio proposed by another embodiment of the present application;
FIG. 7 is a flow chart illustrating the method for reducing post-injection quantity according to an embodiment of the present application;
FIG. 8 is a flow chart of an embodiment of the present application for improving post-injection quantity;
fig. 9 is a schematic block diagram of a control device according to an embodiment of the present application.
Detailed Description
The following description of the embodiments of the present application will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are some, but not all embodiments of the application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.
LNT catalysts generally use noble metals Pt as the catalytically active component, alkali and/or alkaline earth oxides as the storage component, and gamma-ai 2O3 of large specific surface area as the support to increase the dispersion of the active and storage components. A typical LNT catalyst system is Pt/BaO/ai 2O3, the NOx lean burn stage on the LNT catalyst, first in a longer lean burn stage, NO is oxidized to N02 on the noble metal active site Pt, then N02 reacts with the adjacent basic component BaO to form nitrate which is stored; when the engine is switched to a fuel-rich atmosphere, the concentration of the reducing components HC, CO and H2 in the tail gas is rapidly increased in a short time, the nitrate stored in the reducing atmosphere is unstable thermally, N02 can be rapidly released and reduced to N2 by the reducing agent in a catalytic reaction mode, meanwhile, the catalyst storage position is regenerated, and the sample feeding is completed in a standard circulation process of the LNT.
When the LNT enters into DeNOx state, the reducing gas in the engine exhaust is mainly H2 (hydrogen), CO (carbon monoxide) and C3H6 (propylene), H2 has a good reducing capability, the conversion efficiency of CO is slightly lower than H2, and the reducing capability of propylene is poor, so that the LNT cannot be completely regenerated, so that reducing the influence of propylene is an effective means for improving the regeneration effect of the LNT.
Example 1
In view of this, an embodiment of the present application provides an engine control method based on an LNT, referring to fig. 1, the control method includes:
s1, acquiring an air-fuel ratio chart and working parameters of a current engine;
during the operation of the LNT, when the emission amount of propylene reaches a preset emission amount, the LNT is considered to be in a state of high emission amount of propylene, wherein during the operation of the engine, under the same operation condition, the emission amount of propylene changes with the air-fuel ratio of the engine, during the improvement of the air-fuel ratio, the emission amount of propylene decreases with the improvement of the air-fuel ratio, and when the air-fuel ratio reaches a certain value, the emission amount of propylene increases with the improvement of the air-fuel ratio, so that when the emission amount of propylene reaches the preset emission amount, two air-fuel ratios are corresponding, wherein the lower air-fuel ratio is the lower air-fuel ratio of the engine under the current operation condition, the higher air-fuel ratio is the upper air-fuel ratio of the engine under the current operation condition, and when the air-fuel ratio is between the lower air-fuel ratio and the upper air-fuel ratio, the emission amount of propylene is lower than the preset emission amount, namely the LNT is in the normal operation state, and when the air-fuel ratio is lower than the lower air-fuel ratio or higher than the upper air-fuel ratio.
Accordingly, an air-fuel ratio map of the engine, and operating conditions of the engine are acquired for determining the corresponding lower and upper air-fuel ratios when the LNT is in a state of high emission of propylene under the current operating conditions.
Wherein, the lower limit air-fuel ratio and the upper limit air-fuel ratio corresponding to the LNT in the state of high emission of propylene may not be the same among different types of engines and different vehicle types, and therefore, different vehicles correspond to different air-fuel ratio charts.
S2, acquiring a target upper limit air-fuel ratio and a target lower limit air-fuel ratio according to the current working parameters and an air-fuel ratio chart; the air-fuel ratio chart comprises combinations of different working parameters of the engine, and when the emission reaches the preset emission, the corresponding upper limit air-fuel ratio and lower limit air-fuel ratio are achieved.
The air-fuel ratio chart includes at least two determined working conditions, specifically an upper limit air-fuel ratio and a lower limit air-fuel ratio corresponding to when the emission amount reaches the preset emission amount under the combination of a plurality of different working conditions, so that the air-fuel ratio values corresponding to the current working conditions in the air-fuel ratio chart are obtained, namely the lower limit air-fuel ratio and the upper limit air-fuel ratio corresponding to when the LNT is in the state of high emission amount of propylene.
The combination of the two operating conditions may be various, and in some embodiments, the two operating conditions may be engine power and main fuel injection amount, or engine torque and engine speed, and in other embodiments, the combination of other operating conditions of the engine, or a combination of more operating conditions.
S3, when the LNT of the vehicle exhaust aftertreatment system is in a DeNOx state, acquiring the current air-fuel ratio of the engine;
after the lower limit air-fuel ratio and the upper limit air-fuel ratio under the current working condition are obtained, the working mode of the LNT is detected in real time, and when the LNT enters a DeNOx state, the current air-fuel ratio under the current working condition is judged according to the current air-fuel ratio, and whether the propylene discharged through the LNT when the engine works under the current working condition exceeds the preset discharge amount or not is judged.
S4, when the current air-fuel ratio is not between the target upper limit air-fuel ratio and the target lower limit air-fuel ratio, controlling the engine to adjust the post-injection quantity in the DeNOx state so that the current air-fuel ratio is between the target upper limit air-fuel ratio and the target lower limit air-fuel ratio in an adjusting mode of the engine.
According to the lower and upper limit air-fuel ratios and the current air-fuel ratio, when the current air-fuel ratio is not between the target upper and lower limit air-fuel ratios, it can be considered that the propylene emission amount of the LNT exceeds the preset emission amount during the operation of the current engine, so that during the added post-injection, the engine is activated in an adjustment mode, wherein the engine can be controlled to adjust the post-injection amount in the DeNOx state according to the current air-fuel ratio and the target upper and lower limit air-fuel ratios, including increasing or decreasing the post-injection amount, so as to change the current air-fuel ratio, to make the air-fuel ratio between the target upper and lower limit air-fuel ratios, so as to reduce the propylene emission amount in the DeNOx state.
In the running process of the vehicle, the current working condition of the engine and an air-fuel ratio chart of the engine are obtained, the corresponding target upper limit air-fuel ratio and target lower limit air-fuel ratio of the current working condition in the air-fuel ratio chart are obtained according to the current working condition and the air-fuel ratio chart, namely, when the propylene emission amount under the current working condition reaches the preset emission amount, the upper limit value and the lower limit value of the air-fuel ratio are obtained, when the LNT of the vehicle exhaust aftertreatment system is in a DeNOx state, the current air-fuel ratio of the engine is obtained, the current air-fuel ratio is compared with the target upper limit air-fuel ratio and the target lower limit air-fuel ratio, when the air-fuel ratio is not between the target upper limit air-fuel ratio and the target lower limit air-fuel ratio, the propylene emission amount of the engine can be considered to reach the preset emission amount, namely, the LNT is controlled to be in a state of high propylene emission amount, and the post-fuel injection amount of the engine is controlled under the DeNOx state, so that the propylene emission amount of the LNT is reduced, the tail gas treatment effect of the LNT is improved, the propylene emission amount of the LNT can be reduced by adjusting the post-fuel amount of the engine, the LNT is improved, the effect of the exhaust treatment effect of the LNT is effectively reduced, and the LNT development cost is effectively reduced.
In some embodiments, referring to FIG. 2, obtaining the air-fuel ratio map includes:
s101, selecting a working parameter and a test point of air-fuel ratio;
s102, scanning test points, and generating an air-fuel ratio chart.
The working parameters comprise engine power, main fuel injection quantity, engine rotating speed and engine torque, and when the air-fuel ratio chart is obtained, different engine power test quantities and main fuel injection quantity test quantities are mutually combined, so that a plurality of preset working condition test points corresponding to the two working conditions are obtained.
Selecting test points of working parameters and air-fuel ratio, including:
s201, selecting different working parameters, defining preset selecting intervals in respective preset test ranges, and determining a plurality of different first test points;
s202, selecting an air-fuel ratio, defining a preset selecting interval in a preset testing range, and determining a plurality of different second testing points.
Sweeping test points to generate an air-fuel ratio chart, comprising:
s301, acquiring the emission amount of propylene in an engine according to the first test point and the second test point;
s302, determining a lower limit air-fuel ratio and an upper limit air-fuel ratio according to the emission amount
S303, an air-fuel ratio map is generated based on the lower limit air-fuel ratio, the upper limit air-fuel ratio, and the first test point.
In one embodiment, the engine operating conditions are sensed by power and main fuel injection quantity of the engine.
Referring to fig. 5A and 5B, when the air-fuel ratio chart is acquired, firstly, a detection amount of engine power is selected, a test range of the engine power is selected, for example, the test range of the engine power can be 50kw-100kw, a plurality of test amounts are selected according to a preset selection interval in the test range, for example, the selection interval of the engine power can be 10kw, so that one test amount of the engine power is selected every 10kw between 50kw-100kw, and a plurality of test amounts of the engine power are obtained. The test range and the selection interval can be changed according to the model and the model of the engine.
And then selecting the detection quantity of the main injection quantity, and selecting a testing range of the main injection quantity, for example, the testing range of the main injection quantity can be 20mg-60mg, and selecting a plurality of testing quantities according to preset selecting intervals in the testing range, for example, the main injection quantity selecting interval can be 10mg, so that the testing quantity of one main injection quantity is selected every 10mg in the range of 20mg-60mg, and a plurality of main injection quantity testing quantities are obtained.
When the preset emission quantity is used for representing that the propylene emission quantity reaches the threshold value, the working efficiency of the LNT is lower, namely, when the propylene emission quantity reaches the threshold value, the propylene emission quantity needs to be reduced, so that the working efficiency of the LNT is improved, the preset emission quantity is set according to different engine models, vehicle models and LNT models, and in the implementation, the preset emission quantity can be 50ppm. The test range and the selection interval can be changed according to the model and the model of the engine.
In this embodiment, when the air-fuel ratio is detected, the value of the air-fuel ratio may be set according to the actual situation three bits after the decimal point of the value of the air-fuel ratio.
And detecting the lower limit air-fuel ratio when the propylene rises to the preset emission amount and the upper limit air-fuel ratio which is reduced to the preset emission amount again under the condition of the main fuel injection amount and the engine power according to the main fuel injection amount and the engine power of each preset working condition test point.
And obtaining an air-fuel ratio chart comprising an upper limit air-fuel ratio and a lower limit air-fuel ratio corresponding to the combination of different working conditions when the emission reaches the preset emission according to the lower limit air-fuel ratio and the upper limit air-fuel ratio of each preset working condition test point.
When the two working conditions of the air-fuel ratio chart are the main fuel injection quantity and the engine power, the current main fuel injection quantity and the current engine power of the engine are obtained when the current air-fuel ratio is detected.
The upper limit air-fuel ratio and the lower limit air-fuel ratio when the propylene emission amount reaches the preset emission amount in the case of the current main fuel injection amount and the current engine power are obtained as target upper limit air-fuel ratio and target lower limit air-fuel ratio under the current operating condition as target upper limit air-fuel ratio and target lower limit air-fuel ratio for determining whether the current air-fuel ratio is between the target upper limit air-fuel ratio and the target lower limit air-fuel ratio in the air-fuel ratio map.
In another embodiment, the engine torque and engine speed are detected as operating conditions of the engine.
Referring to fig. 6A and 6B, when the air-fuel ratio map is acquired, firstly, a detected amount of the engine speed is selected, and a test range of the engine speed is selected, for example, the test range of the engine speed may be 1200rpm-2800rpm, and in the test range, a plurality of test amounts are selected according to a preset selection interval, for example, the selection interval of the engine speed may be 400rpm, so that between 1200rpm-2800rpm, one test amount of the engine speed is selected every 400rpm, and a plurality of test amounts of the engine speed are obtained. The test range and the selection interval can be changed according to the model and the model of the engine.
Then, the detection quantity of the engine torque is selected, a test range of the engine torque is selected, for example, the test range of the engine torque can be 50Nm-300Nm, a plurality of test quantities are selected according to preset selection intervals in the test range, for example, the engine torque selection intervals can be 50Nm, so that one test quantity of the engine torque is selected every 50Nm in the range of 50Nm-300Nm, and a plurality of engine torque test quantities are obtained. The test range and the selection interval can be changed according to the model and the model of the engine.
In this embodiment, when the air-fuel ratio is detected, the value of the air-fuel ratio may be set according to the actual situation three bits after the decimal point of the value of the air-fuel ratio.
And combining the different engine torque test amounts with the engine rotation speed test amounts to obtain a plurality of preset working condition test points corresponding to the two working conditions, namely, different engine rotation speeds correspond to different engine torques.
Based on the engine torque and the engine speed at each of the preset operating condition test points, a lower limit air-fuel ratio at which propylene rises to a preset emission amount and an upper limit air-fuel ratio at which propylene falls again to the preset emission amount are detected in the case of the engine torque and the engine speed.
And obtaining an air-fuel ratio chart comprising an upper limit air-fuel ratio and a lower limit air-fuel ratio corresponding to the combination of different working conditions when the emission reaches the preset emission according to the lower limit air-fuel ratio and the upper limit air-fuel ratio of each preset working condition test point.
An upper limit air-fuel ratio and a lower limit air-fuel ratio at which the propylene emission amount reaches the preset emission amount in the case of the current engine speed and the current engine torque are obtained as target upper limit air-fuel ratio and target lower limit air-fuel ratio under the current operating condition in the air-fuel ratio map, for determining whether the current air-fuel ratio is between the target upper limit air-fuel ratio and the target lower limit air-fuel ratio.
In some embodiments, referring to FIG. 8, when in the DeNOx state and the current air-fuel ratio is not between the target upper limit air-fuel ratio and the target lower limit air-fuel ratio, the adjustment mode of the engine is activated to adjust the post-injection amount of the engine in the DeNOx state, including
S401, when the current air-fuel ratio is detected to be smaller than or equal to the target lower limit air-fuel ratio, an adjusting mode of the engine is detected, and a difference value between the current air-fuel ratio and the target lower limit air-fuel ratio is acquired;
s402, in the adjustment mode, the post-injection quantity of the engine in the DeNOx state is determined to be reduced according to the difference value, so that the current air-fuel ratio is improved.
When the current air-fuel ratio is detected to be smaller than or equal to the target lower limit air-fuel ratio, the current air-fuel ratio is lower, the post-injection quantity adjustment quantity required for compensating the difference is calculated according to the difference between the current air-fuel ratio and the target air-fuel ratio, and the post-injection quantity of the engine in the DeNOx state is reduced to improve the current air-fuel ratio, so that the emission quantity of propylene is reduced.
S501, upon detecting that the current air-fuel ratio is greater than the target lower limit air-fuel ratio, an adjustment mode of the engine, and acquiring a difference between the current air-fuel ratio and the target lower limit air-fuel ratio;
s502, in the adjustment mode, the post-injection quantity of the engine in the DeNOx state is determined to be improved according to the difference value, so that the current air-fuel ratio is improved.
When the current air-fuel ratio is detected to be greater than or equal to the target upper limit air-fuel ratio, the current air-fuel ratio is higher, the post-injection quantity adjustment quantity required for compensating the difference is calculated according to the difference between the current air-fuel ratio and the target air-fuel ratio, and the post-injection quantity of the engine in the DeNOx state is improved to reduce the current air-fuel ratio, so that the emission quantity of propylene is reduced.
Example two
Based on the same inventive concept, another embodiment of the present application provides an engine control apparatus based on an LNT, referring to fig. 9, the control apparatus 6 includes:
a detection module 61, configured to acquire a plurality of current operating conditions of the engine and an air-fuel ratio map corresponding to the operating conditions in real time;
a determining module 62, configured to find a target upper limit air-fuel ratio and a target lower limit air-fuel ratio corresponding to a plurality of current operating conditions in the air-fuel ratio icon based on the air-fuel ratio map; wherein the air-fuel ratio chart comprises an upper limit air-fuel ratio and a lower limit air-fuel ratio corresponding to the combination of different working conditions when the emission reaches a preset emission;
an obtaining module 63, configured to obtain a current air-fuel ratio of the engine when the vehicle exhaust aftertreatment system LNT is in a DeNOx state;
an adjustment module 64 for controlling the engine to adjust the post injection amount in the DeNOx state so that the current air-fuel ratio is between the target upper limit air-fuel ratio and the target lower limit air-fuel ratio when the current air-fuel ratio is not between the target upper limit air-fuel ratio and the target lower limit air-fuel ratio.
In some embodiments, the control device further comprises: the map acquisition module 65 is configured to acquire an air-fuel ratio map.
In some embodiments, the chart acquisition module 65 is further configured to perform the steps of:
selecting a plurality of preset selection intervals defined by different working conditions in respective preset test ranges, and determining a plurality of preset working condition test points; wherein the different operating conditions include engine power and main fuel injection quantity;
acquiring a lower limit air-fuel ratio and an upper limit value corresponding to each preset working condition test point when the emission of propylene of the engine reaches the preset emission;
an air-fuel ratio map is generated based on the plurality of lower limit air-fuel ratios and the plurality of upper limit air-fuel ratios.
Wherein the detection module 61 and the determination module 62 are further configured to perform the following steps:
the detection module 61 acquires the current main fuel injection quantity and the current engine power of the engine in real time;
the determination module 62 determines an upper and lower air-fuel ratio corresponding to the current main injection amount and the current engine power based on the air-fuel ratio map.
In some embodiments, the chart acquisition module 65 is further configured to perform the steps of:
selecting a plurality of preset selection intervals defined by different working conditions in respective preset test ranges, and determining a plurality of preset working condition test points; wherein the different operating conditions include engine torque and engine speed;
acquiring a lower limit air-fuel ratio and an upper limit value corresponding to each preset working condition test point when the emission of propylene of the engine reaches the preset emission;
an air-fuel ratio map is generated based on the plurality of lower limit air-fuel ratios and the plurality of upper limit air-fuel ratios.
Wherein the detection module 61 and the determination module 62 are further configured to perform the following steps:
the detection module 61 acquires the current rotation speed and the current torque of the engine in real time;
the determination module 62 determines an upper limit air-fuel ratio and a lower limit air-fuel ratio corresponding to the current rotation speed and the current torque based on the air-fuel ratio map, thereby obtaining an air-fuel ratio preset interval.
In some embodiments, the adjustment module 64 is further configured to perform the steps of:
when the current air-fuel ratio is detected to be less than or equal to the target lower limit air-fuel ratio, reducing the post-injection amount of the engine in the DeNOx state to increase the current air-fuel ratio;
when it is detected that the current air-fuel ratio is greater than or equal to the target upper limit air-fuel ratio, the post-injection amount of the engine in the DeNOx state is increased to decrease the current air-fuel ratio.
When the current air-fuel ratio is detected to be smaller than or equal to the target lower limit air-fuel ratio, a difference value between the current air-fuel ratio and the target lower limit air-fuel ratio is acquired;
when the current air-fuel ratio is detected to be greater than or equal to the target upper limit air-fuel ratio, a difference value between the current air-fuel ratio and the target upper limit air-fuel ratio is acquired;
and determining the reduced or increased post-injection quantity according to the difference value.
Based on the same inventive concept, another embodiment of the present application provides a vehicle, including a control device as described above, to implement the control method described above.
For the device embodiments, since they are substantially similar to the method embodiments, the description is relatively simple, and reference is made to the description of the method embodiments for relevant points.
In this specification, each embodiment is described in a progressive manner, and each embodiment is mainly described by differences from other embodiments, and identical and similar parts between the embodiments are all enough to be referred to each other.
It will be apparent to those skilled in the art that embodiments of the present application may be provided as a method, apparatus, or computer program product. Accordingly, embodiments of the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, embodiments of the application may take the form of a computer program product on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) having computer-usable program code embodied therein.
Embodiments of the present application are described with reference to flowchart illustrations and/or block diagrams of methods, terminal devices (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing terminal device to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing terminal device, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
While preferred embodiments of the present application have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. It is therefore intended that the following claims be interpreted as including the preferred embodiment and all such alterations and modifications as fall within the scope of the embodiments of the application.
Finally, it is further noted that relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or terminal that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or terminal. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article or terminal device comprising the element.
The engine control method, device and vehicle based on the LNT provided by the application are described in detail, and specific examples are applied to illustrate the principle and implementation of the application, and the description of the examples is only used for helping to understand the method and core idea of the application; meanwhile, as those skilled in the art will have variations in the specific embodiments and application scope in accordance with the ideas of the present application, the present description should not be construed as limiting the present application in view of the above.
Claims (7)
1. An engine control method based on an LNT, the control method comprising:
acquiring an air-fuel ratio chart and working parameters of a current engine;
acquiring a target upper limit air-fuel ratio and a target lower limit air-fuel ratio according to the current working parameters and an air-fuel ratio chart;
wherein the air-fuel ratio chart comprises combinations of different working parameters of the engine, and when the emission reaches a preset emission, the corresponding upper limit air-fuel ratio and lower limit air-fuel ratio are adopted;
acquiring a current air-fuel ratio of the engine when the vehicle exhaust aftertreatment system is in a DeNOx state;
activating an adjustment mode of the engine when the DeNOx state is set and the current air-fuel ratio is not between a target upper limit air-fuel ratio and a target lower limit air-fuel ratio, and adjusting a post injection amount of the engine in the DeNOx state so that the current air-fuel ratio is between the target upper limit air-fuel ratio and the target lower limit air-fuel ratio;
acquiring the air-fuel ratio map, including:
selecting test points of the working parameters and the air-fuel ratio;
scanning the test points to generate the air-fuel ratio chart;
selecting test points of the working parameters and the air-fuel ratio, wherein the test points comprise:
selecting different working parameters, defining preset selection intervals in respective preset test ranges, and determining a plurality of different first test points;
selecting an air-fuel ratio, defining a preset selecting interval in a preset testing range, and determining a plurality of different second testing points;
sweeping the test point to generate the air-fuel ratio chart, including:
according to the first test point and the second test point, acquiring the emission amount of propylene in the engine;
determining the lower limit air-fuel ratio and the upper limit air-fuel ratio according to the emission amount;
the air-fuel ratio map is generated based on the lower limit air-fuel ratio, the upper limit air-fuel ratio, and the first test point.
2. The control method according to claim 1, characterized in that when the DeNOx state is in which the current air-fuel ratio is not between a target upper limit air-fuel ratio and a target lower limit air-fuel ratio, activating an adjustment mode of the engine to adjust a post-injection amount of the engine in the DeNOx state includes:
activating an adjustment mode of the engine and acquiring a difference between the current air-fuel ratio and the target lower limit air-fuel ratio when it is detected that the current air-fuel ratio is less than or equal to the target lower limit air-fuel ratio;
in the adjustment mode, the post injection amount of the engine in the DeNOx state is determined to be reduced according to the difference value so as to improve the current air-fuel ratio.
3. The control method according to claim 1, characterized in that when the DeNOx state is in which the current air-fuel ratio is not between a target upper limit air-fuel ratio and a target lower limit air-fuel ratio, activating an adjustment mode of the engine to adjust a post-injection amount of the engine in the DeNOx state includes:
activating an adjustment mode of the engine and acquiring a difference between the current air-fuel ratio and the target lower limit air-fuel ratio when it is detected that the current air-fuel ratio is greater than the target lower limit air-fuel ratio;
in the adjustment mode, the post injection amount of the engine in the DeNOx state is determined to be increased according to the difference value so as to reduce the current air-fuel ratio.
4. A control method according to any one of claim 1 to 3,
the operating parameters include engine power, main injection quantity, engine speed and engine torque.
5. An LNT-based engine control apparatus, the control apparatus comprising:
the detection module is used for acquiring a plurality of current working conditions of the engine and an air-fuel ratio chart corresponding to the working conditions in real time;
the determining module is used for searching a target upper limit air-fuel ratio and a target lower limit air-fuel ratio corresponding to the plurality of current working conditions in the air-fuel ratio icon based on the air-fuel ratio chart; wherein the air-fuel ratio chart comprises an upper limit air-fuel ratio and a lower limit air-fuel ratio corresponding to the combination of different working conditions when the emission reaches a preset emission;
the acquisition module is used for acquiring the current air-fuel ratio of the engine when the LNT of the vehicle exhaust aftertreatment system is in a DeNOx state;
an adjustment module configured to activate an adjustment mode of the engine when the current air-fuel ratio is not between a target upper limit air-fuel ratio and a target lower limit air-fuel ratio, and control the engine to adjust a post-injection amount in the DeNOx state so that the current air-fuel ratio is between the target upper limit air-fuel ratio and the target lower limit air-fuel ratio;
acquiring the air-fuel ratio map, including:
selecting test points of the working parameters and the air-fuel ratio;
scanning the test points to generate the air-fuel ratio chart;
selecting test points of the working parameters and the air-fuel ratio, wherein the test points comprise:
selecting different working parameters, defining preset selection intervals in respective preset test ranges, and determining a plurality of different first test points;
selecting an air-fuel ratio, defining a preset selecting interval in a preset testing range, and determining a plurality of different second testing points;
sweeping the test point to generate the air-fuel ratio chart, including:
according to the first test point and the second test point, acquiring the emission amount of propylene in the engine;
determining the lower limit air-fuel ratio and the upper limit air-fuel ratio according to the emission amount;
the air-fuel ratio map is generated based on the lower limit air-fuel ratio, the upper limit air-fuel ratio, and the first test point.
6. The control device according to claim 5, characterized in that the control device further comprises:
and the chart acquisition module is used for acquiring the air-fuel ratio chart.
7. A vehicle comprising a control device according to claim 5 or 6 to implement the control method according to any one of claims 1 to 4.
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