CN116044586A - Target EGR rate control method under idle working condition - Google Patents

Target EGR rate control method under idle working condition Download PDF

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Publication number
CN116044586A
CN116044586A CN202211528641.5A CN202211528641A CN116044586A CN 116044586 A CN116044586 A CN 116044586A CN 202211528641 A CN202211528641 A CN 202211528641A CN 116044586 A CN116044586 A CN 116044586A
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egr rate
working condition
under
idle
speeddiff
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秦龙
杨柳春
雷雪
李京
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Dongfeng Motor Group Co Ltd
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Dongfeng Motor Group Co Ltd
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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
    • F02D41/0025—Controlling engines characterised by use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
    • F02D41/0047—Controlling exhaust gas recirculation [EGR]
    • F02D41/005—Controlling exhaust gas recirculation [EGR] according to engine operating conditions
    • F02D41/0052—Feedback control of engine parameters, e.g. for control of air/fuel ratio or intake air amount
    • 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
    • F02D41/1401—Introducing closed-loop corrections characterised by the control or regulation method
    • F02D41/1402—Adaptive control
    • 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
    • F02D41/24—Electrical control of supply of combustible mixture or its constituents characterised by the use of digital means
    • F02D41/2406—Electrical control of supply of combustible mixture or its constituents characterised by the use of digital means using essentially read only memories
    • F02D41/2425—Particular ways of programming the data
    • F02D41/2429—Methods of calibrating or learning
    • F02D41/2451—Methods of calibrating or learning characterised by what is learned or calibrated
    • 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
    • F02D41/24—Electrical control of supply of combustible mixture or its constituents characterised by the use of digital means
    • F02D41/2406—Electrical control of supply of combustible mixture or its constituents characterised by the use of digital means using essentially read only memories
    • F02D41/2425—Particular ways of programming the data
    • F02D41/2429—Methods of calibrating or learning
    • F02D41/2477—Methods of calibrating or learning characterised by the method used for learning
    • 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)
  • Exhaust-Gas Circulating Devices (AREA)
  • Combined Controls Of Internal Combustion Engines (AREA)

Abstract

The invention belongs to the technical field of engines, and discloses a target EGR rate control method under idle working conditions, which comprises the following steps: determining an original value r of EGR rate under idle conditions EGRIdleAcitve,raw The method comprises the steps of carrying out a first treatment on the surface of the Determining an ideal value r of EGR rate under idle conditions EGRIdleAcitve,Setpoint The method comprises the steps of carrying out a first treatment on the surface of the Determining an EGR rate final value r under idle working conditions according to the EGR rate ideal value under idle working conditions EGRIdleAcitve,Final . The invention solves the problem that the engine has poor combustion stability due to improper introduction of the EGR rate when the engine is in an idle working condition.

Description

Target EGR rate control method under idle working condition
Technical Field
The invention belongs to the technical field of engines, and particularly relates to a target EGR rate control method under idle working conditions.
Background
Studies have shown that exhaust gas recirculation (Exhaust Gas Recirculation, EGR) systems have certain advantages in improving emissions, reducing fuel consumption, and improving antiknock capabilities. The EGR exhaust gas reduces the combustion temperature, avoids knocking, and suppresses the ignition advance retardation. However, when the EGR rate is not properly introduced, including unstable control of large fluctuation of EGR exhaust gas or excessive EGR rate, combustion stability is adversely affected, and at this time, it is necessary to appropriately retard the ignition angle to suppress occurrence of knocking or abnormal engine shake.
When the engine is in an idle working condition, the requirement on the rotating speed control precision is very high, and if the engine combustion stability is worse due to improper introduction of the EGR rate, a customer can feel vehicle shake more, and the service life and NVH of the engine are influenced. It is necessary to perform EGR rate control optimization during idle conditions.
Based on the method, the EGR rate control method under the idle working condition is provided, the EGR rate control of the engine under the idle working condition is optimized, and the self-learning can be carried out in the whole life cycle of the engine.
Disclosure of Invention
Aiming at the technical problems, the invention provides a target EGR rate control method under an idle working condition, which aims to optimize the EGR rate control of an engine under the idle working condition and can perform self-learning in the whole life cycle of the engine.
The application provides a target EGR rate control method under idle working conditions, which comprises the following steps:
step 1, determining an original value r of an EGR rate under idle working conditions EGRIdleActive，raw ：
Figure SMS_1
wherein ,rEGRIdleActive，mapped Is the basic value, k, of the original value of the EGR rate SpeedDiff 、k SpeedDerivativeDiff 、k ElectricalLoad、 k Coolant 、k AirTrqSparkTrqDiff 、k CatHeating 、
Figure SMS_2
A correction factor for the EGR rate of idle speed regulation;
step 2, determining an ideal value r of the EGR rate under the idle working condition EGIdleAct ive，Setpo int ：
r EGRIdleActive，Setpo int ＝r EGRIdleActive，raw ×(1+r IdleAdpationRatio) wherein ,rIdleAdpationRatio The EGR rate self-learning correction factor is used for the EGR rate self-learning correction factor under the idle working condition;
step 3, determining an EGR rate final value r under the idle working condition according to the EGR rate ideal value under the idle working condition EGRIdleActive，Final 。
Specifically, r is determined from the engine speed n and the load rho EGRIdleActive，mapped Wherein the load is the in-cylinder fresh air density.
Specifically, in step 1, the correction factor of the EGR rate is determined by:
1) According to the engine speed n and the speed difference n between the target speed and the actual speed SpeedDiff Determining k SpeedDiff ；
The engine speed is unchanged, the larger the speed difference is, k SpeedDiff The smaller;
the higher the engine speed, k SpeedDiff The larger;
2) According to the rotation speed difference n SpeedDiff And a rotational speed difference change rate dn SpeedDiff Determining k SpeedDerivativeDiff ；
The rotation speed difference is unchanged, the greater the rotation speed difference change rate is, k SpeedDerivativeDiff The smaller;
the change rate of the rotation speed difference is unchanged, and the larger the rotation speed is, k is SpeedDerivativeDiff The smaller;
3) Torque ratio of torque according to engine speed and electric load to torque of idle gas circuit
Figure SMS_3
Determining k Electrical Load ；
The higher the ratio of torque, k, the constant the engine speed Electrical Load The smaller;
the torque ratio is unchanged, the greater the engine speed, k Electrical Load The larger;
4) Determining k from engine water temperature Coolant ；
5) Based on the engine speed and the torque of the idle gas circuit and the torque of the idle fire circuitDetermining the difference in torque k AirTrqSparkTrqDiff ；
The higher the difference in torque, k, the constant the engine speed AirTrqSparkTrqDiff The larger;
the torque difference is unchanged, the higher the engine speed, k AirTrqSparkTrqDiff The larger;
6) According to the ignition efficiency r in the catalyst ignition process CatHeatingSparkEff And engine speed determination k CatHeating ；
The engine speed is unchanged, the greater the ignition efficiency is, k CatHeating The larger;
the ignition efficiency is unchanged, the higher the engine speed is, k CatHeating The larger;
7) According to the speed v and the gear Cnt of the vehicle gearbox Gear Determination of
Figure SMS_4
The vehicle speed is unchanged, the bigger the gear is,
Figure SMS_5
the smaller;
the gear is not changed, the larger the vehicle speed is,
Figure SMS_6
the larger.
Specifically, in 2), the rotation speed difference change rate dn SpeedDiff The method comprises the following steps:
Figure SMS_7
wherein ,
Figure SMS_8
for the rate of change of the rotational speed difference of the last sampling period,/->
Figure SMS_9
For the rotation speed difference of the last sampling period, deltat is the sampling period, t c A filter time constant for calculating the rate of change of the rotational speed difference.
In step 2, continuously self-learning the whole life cycle of the engine, and storing a learning value of an EGR rate self-learning correction factor under an idle working condition in an EEPROM of the controller after power-off; when the vehicle is off line, the EGR rate self-learning correction factor r under idle working condition IdleAdpati onRatio Is 0.
Specifically, step 3 includes three cases:
case 1, speed difference m SeedDiff Absolute value of |n SppedDiff I is greater than a first preset value n SeedDiffM arg in And absolute value of rotation speed difference |n SpeedDiff Absolute value of engine speed difference that is larger than last sampling period
Figure SMS_10
At the time, EGR rate r under idle condition EGRIdleAct ive，Final The method comprises the following steps:
r EGRIdleActive，Fina ＝r EGRIdleActive ，S etpoint ×K SpeedDiff ；
at this time, if the absolute value |n of the rotational speed difference is detected SpeedDiff I is greater than a first preset value n SpeedDiffM arg in If the time is longer than T1, the EGR rate self-learning state under the idle working condition is the EGR rate downward learning state under the idle working condition;
under the current working condition, EGR rate self-learning correction factor r under idle working condition IdleAdpati onRatio The learning state is only recorded when the updating is not learned;
case 2, absolute value of rotational speed difference |n SpeedDiff I is not greater than a first preset value n SpeedDiffM arg in But greater than a second preset value n SpeedDiffM arg in1 Or absolute value of rotation speed difference |n SpeedDiff Absolute value of engine speed difference of not more than the last sampling period
Figure SMS_11
At the time, EGR rate r under idle condition EGRId;eAct ive，Final The method comprises the following steps: r is (r) EGRIdleActive，Fina ＝r EGRIdleActive，Setpo int ×k SpeedDiff After T2 time, the EGR rate under idle working condition is increased by the rate R1, oneOnce the absolute value of the rotational speed difference |n is detected SpeedDiff I is greater than a first preset value n SpeedDiffN arg in The EGR rate self-learning state under the idle working condition is the EGR rate downward learning state under the idle working condition;
if in the process, the absolute value |n of the rotational speed difference is not detected SpeedDiff I is greater than a first preset value n SpeedDiffM arg in If the time exceeds T2, the EGR rate self-learning state under the idle working condition is the EGR rate upward learning state under the idle working condition;
under the current working condition, EGR rate self-learning correction factor r under idle working condition IdleAdpatoinRatio The learning state is only recorded when the updating is not learned;
case 3, when neither case 1 nor case 2 are satisfied, the EGR rate r under idle conditions EGRIdleActive，Final Is the EGR rate r under idle working condition EGRIdleActive，Setpoint ；
If the EGR rate self-learning state under the idle working condition in the last sampling period is detected to be the EGR rate upward learning state under the idle working condition, the EGR rate self-learning correction factor under the idle working condition rIdleAdpationRatio Increasing at a rate k 2;
if the EGR rate self-learning state under the idle working condition in the last sampling period is detected to be the EGR rate downward learning state under the idle working condition, the EGR rate self-learning correction factor r under the idle working condition IdleAdpationRatio Decrease at a rate k3, where k2 < |k3|.
Specifically, EGR rate r under idle conditions EGRIDIeActive，Final Is limited between a maximum value MAX and a minimum value MIN, wherein the maximum value MAX is determined according to the engine speed n and the load rho, and the minimum value MIN is 0.
Specifically, in case 1, k SpeedDiff From the engine speed n and the speed difference n between the target speed and the actual speed SpeedDiff Together determine the rotational speed difference n SpeedDiff Taking the maximum value and the minimum value of the rotation speed difference before the last N sampling periods, wherein the smaller the rotation speed of the engine is, the smaller the N value is, and the larger the rotation speed of the engine is, and the larger the N value is.
Specifically, in case 2,a second preset value n SpeedDiffMarg in1 Design accuracy n for engine speed fluctuation SpeedDiffPrecision Is 1 times larger than the k.
Specifically, the priority of case 1 is higher than the priority of case 2, and the priority of case 2 is higher than the priority of case 3.
According to the target EGR rate control method under the idle working condition, the EGR rate control of the engine under the idle working condition is optimized, and self-learning can be performed in the whole life cycle of the engine. The method ensures the stability of idle speed control, simultaneously ensures the advantage of EGR rate as much as possible, and carries out learning and updating when the fluctuation of the rotating speed is further aggravated, so that incorrect idle speed working condition EGR rate control is not caused by different life cycles of the engine.
Drawings
FIG. 1 is a flow chart of a target EGR rate control method under idle conditions in accordance with the present invention;
FIG. 2 is a logic diagram of a target EGR rate control method under idle conditions in accordance with the present invention.
Detailed Description
The present invention will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be apparent that the particular embodiments described herein are merely illustrative of the present invention and are some, but not all embodiments of the present invention. All other embodiments, which can be made by one of ordinary skill in the art without undue burden on the person of ordinary skill in the art based on embodiments of the present invention, are within the scope of the present invention.
The calculation period (sampling period) of the method of the invention is 10ms, namely, the original value of the EGR rate, the ideal value of the EGR rate and the final value of the EGR rate are updated every 10ms.
FIG. 1 is a flowchart of an embodiment of a method for controlling a target EGR rate under idle conditions according to the present invention, where the flowchart specifically includes:
step 1, determining an original value r of an EGR rate under idle working conditions EGRIdleActive，raw ：
Figure SMS_12
wherein ,rEGRIdleActive，mapped Is the basic value, k, of the original value of the EGR rate SpeedDiff 、k SpeedDerivativeDiff 、k ElectricalLoad 、k Coolant 、k AirTrqSparkTrqDiff 、k CatHeating 、
Figure SMS_13
Is a correction factor for the EGR rate of idle speed regulation.
Specifically, r is determined from the engine speed n and the load rho EGRIdleActive，mapped Wherein the load is the in-cylinder fresh air density.
And (3) adjusting the EGR rate according to the idle working conditions (different rotating speeds and loads), avoiding the influence of combustion stability, and calibrating the combustion stability COV not to exceed 3%. R in the examples of the present application EGRIdleActive，mapped The values are shown in Table 1.
TABLE 1
Figure SMS_14
k SpeedDerivativeDiff For regulation and control according to the concrete expression result of the idle speed, regulation is carried out according to the fluctuation condition, namely feedback regulation and protection after abnormal rotation speed; while
Figure SMS_15
The active regulation is to suppress abnormal fluctuation, and the advanced suppression can be called feedforward regulation.
Specifically, the correction factor of the EGR rate is determined by:
1) According to the engine speed n and the speed difference n between the target speed and the actual speed SpeedDiff Determining k SpeedDiff 。
The engine speed is unchanged, the larger the speed difference is, k SpeedDiff The smaller; the higher the engine speed, k SpeedDiff The larger.
2) According to the rotation speed difference n SpeedDiff And a rotational speed difference change rate dn SpeedDiff Determining k SpeedDerivativeDiff 。
The rotation speed difference is unchanged, the greater the rotation speed difference change rate is, k SpeedDerivativeDiff The smaller; the change rate of the rotation speed difference is unchanged, and the larger the rotation speed is, k is SpeedDerivativeDiff The smaller.
The rotation speed difference is unchanged, the greater the rotation speed difference change rate is, k SpeedDerivativeDiff The smaller the impact on the rotation speed fluctuation is reduced; the change rate of the rotation speed difference is unchanged, and the larger the rotation speed is, k is SpeedDerivativeDiff The smaller the calibration basis is, the more the fluctuation of the rotation speed is ensured to be within +/-15 rpm, and the EGR rate is improved as much as possible.
Specifically, the rotational speed difference change rate dn SpeedDiff The method comprises the following steps:
Figure SMS_16
wherein ,
Figure SMS_17
for the rate of change of the rotational speed difference of the last sampling period,/->
Figure SMS_18
For the rotation speed difference of the last sampling period, deltat is the sampling period, t c A filter time constant for calculating the rate of change of the rotational speed difference.
Preferably dn SpeedDiff (0) Taking 0, n SpeedDiff (0) Taking 0, the sampling period is 10ms.
t c To calculate the filter time constant for the rate of change of the speed difference, the present embodiment is determined from the engine speed and load as shown in table 2.
TABLE 2
Figure SMS_19
Final k SpeedDerivativeDiff The calibration data for this example are shown in table 3.
TABLE 3 Table 3
Figure SMS_20
Figure SMS_21
All the calibration bases ensure that the fluctuation of the rotating speed is within +/-15 rpm.
3) Torque ratio of torque according to engine speed and electric load to torque of idle gas circuit
Figure SMS_22
Determining k Electricai Load 。
The higher the ratio of torque, k, the constant the engine speed ElectricalLoad The smaller; the torque ratio is unchanged, the greater the engine speed, k ElectricalLoad The larger.
The higher the ratio of torque, k, the constant the engine speed Electrical Load The smaller the load torque is regulated in the idle speed control to ensure the normal operation of the load, and the influence of the overlarge EGR rate on the stable operation of the load is required to be avoided; the torque ratio is unchanged, the greater the engine speed, k Electrical Load The larger the engine is, the calibration basis is to ensure that the fluctuation of the rotating speed is within +/-20 rpm under the premise of electric load, so that the EGR rate is improved as much as possible. Calibration of several other correction factors is that the absence of an electrical load is a determined calibration parameter.
K in the embodiment of the application Electrical Load The values are shown in Table 4.
TABLE 4 Table 4
Figure SMS_23
4) Determining k from engine water temperature Coolant 。
The water temperature of the engine is an important parameter of the temperature of the mixture entering the combustion of the cylinder, the more moderate the water temperature is, the better the combustion of the engine is, the smaller the fluctuation of the rotating speed is, and the calibration is based on the premise of ensuring that the fluctuation of the rotating speed is within +/-20 rpm under the condition of electric load as well, so that the EGR rate is improved as much as possible.
K in the embodiment of the application Coolant The values are shown in Table 5.
TABLE 5
Figure SMS_24
5) Determining k according to the engine speed and the difference between the torque of the idle gas circuit and the torque of the idle fire circuit AirTrqSpar kTrqDiff 。
The higher the difference in torque, k, the constant the engine speed AirTrqSparkTrqDiff The larger; the torque difference is unchanged, the higher the engine speed, k AirTrqSparkTrqDiff The larger.
The higher the difference in torque, k, the constant the engine speed AirTrqSparkTrqDiff The larger the rotation speed fluctuation is, the increase of the road torque can be realized by adjusting the ignition angle, and the EGR rate is not required to be excessively adjusted; the torque difference is unchanged, the higher the engine speed, k AirTrqSpar kTrqDiff The larger the EGR rate is, the calibration basis is also to ensure that the fluctuation of the rotating speed is within +/-20 rpm, so that the EGR rate is improved as much as possible.
K in the embodiment of the application AirTrqSpar kTrqDiff The values are shown in Table 6.
TABLE 6
Figure SMS_25
6) According to the ignition efficiency r in the catalyst ignition process CatHeatingSparkEff And engine speed determination k CatHeating 。
The engine speed is unchanged, the greater the ignition efficiency is, k CatHeating The larger; the ignition efficiency is unchanged, the higher the engine speed is, k CatHeating The larger.
The engine speed is unchanged, the greater the ignition efficiency is, k CatHeating The larger the idle speed control can be by adjusting the ignition efficiencyThe abnormal rotation speed fluctuation is realized, and the EGR is not required to be excessively regulated to avoid the rotation speed fluctuation; the ignition efficiency is unchanged, the higher the engine speed is, k CatHeating The larger the engine is, the calibration basis is to ensure that the fluctuation of the rotating speed is within +/-20 rpm under the premise of electric load, so that the EGR rate is improved as much as possible.
K in the embodiment of the application CatHeating The values are shown in Table 7.
TABLE 7
Figure SMS_26
7) According to the speed v and the gear Cnt of the vehicle gearbox Gear Determination of
Figure SMS_27
The vehicle speed is unchanged, the bigger the gear is,
Figure SMS_28
the smaller; the gear is unchanged, the greater the vehicle speed is, +.>
Figure SMS_29
The larger.
wherein ,CntGear =0 indicates that the vehicle is in neutral, or P is in gear or unknown
The vehicle speed is unchanged, the bigger the gear is,
Figure SMS_30
the smaller the fluctuation of the rotation speed is, the more obvious the vehicle shake is caused, and the EGR is required to be regulated to avoid the shake of the rotation speed and the vehicle speed; the gear is unchanged, the greater the vehicle speed is, +.>
Figure SMS_31
The larger the vehicle inertia effect is, the fluctuation is improved without excessively adjusting the EGR rate, and the calibration basis is that the fluctuation of the rotating speed is ensured to be within +/-20 rpm under the premise of electric load, so that the EGR rate is improved as much as possible. />
In the embodiment of the application
Figure SMS_32
The values are shown in Table 8.
TABLE 8
Figure SMS_33
Step 2, determining an ideal value E of the EGR rate under the idle working condition GRIdleActive，Setpoint ：
r EGRIdleAct ive，Setpo int ＝r EGRIdleAct ive，raw ×(1+r IdleAdpationRatio )
wherein ,rIdleAdpationRation And the EGR rate self-learning correction factor is used for the EGR rate self-learning correction factor under the idle working condition.
In step 2, continuously self-learning the whole life cycle of the engine, and storing a learning value of an EGR rate self-learning correction factor under an idle working condition in an EEPROM of the controller after power-off; when the vehicle is off line, the EGR rate self-learning correction factor r under idle working condition IdleAdpationRation Is 0.
Step 3, determining an EGR rate final value r under the idle working condition according to the EGR rate ideal value under the idle working condition EGRIdleAct ive，Final 。
Specifically, step 3 includes three cases:
case 1, speed difference n SpeedDiff Absolute value of |n SpeedDiff I is greater than a first preset value n SpeedDiffM arg in And absolute value of rotation speed difference |n SpeedDiff Absolute value of engine speed difference that is larger than last sampling period
Figure SMS_34
At the time, EGR rate r under idle condition EGRIdleAct ive，Final The method comprises the following steps: r is (r) EGRIdleActive，Fina ＝r EGRIdleActive，Setpo int× k SpeedDiff 。
Preferably, the engine speed fluctuation design accuracy n of the embodiment of the present application SpeedDiff Pr ecision Taking 15rpm, the first preset value n SpeedDiffM arg in Design accuracy n for engine speed fluctuation SpeedDiff Pr ecision 1.8 times, i.e. 27rpm.
Preferably, the last sampling period is the last 10ms sampling period.
Rotational speed difference n SpeedDiff Absolute value of |n SpeedDiff I is greater than a first preset value n SpeedDiffM arg in And absolute value of rotation speed difference |n SpeedDiff Absolute value of engine speed difference that is larger than last sampling period
Figure SMS_35
The current working condition is indicated to be easy to generate rotation speed fluctuation, and the rotation speed fluctuation is further increased.
Preferably, the last sampling period is the last 10ms sampling period.
Specifically, k SpeedDiff From the engine speed n and the speed difference n between the target speed and the actual speed SpeedDiff Together determine the rotational speed difference n SpeedDiff Taking the maximum value and the minimum value of the rotation speed difference before the last N sampling periods, wherein the smaller the rotation speed of the engine is, the smaller the N value is, and the larger the rotation speed of the engine is, and the larger the N value is.
The engine speed is unchanged, the larger the speed difference is, k SpeedDiff The smaller the impact on the rotation speed fluctuation is reduced; the higher the engine speed, k SpeedDiff The larger the EGR rate is, the less obvious the abnormal fluctuation of the rotating speed is, and the advantage of using the EGR as much as possible is achieved, and the calibration basis is that the fluctuation of the rotating speed is ensured to be within +/-15 rpm, and the EGR rate is improved as much as possible.
The smaller the engine speed is, the smaller the N value is, the larger the engine speed is, and the larger the N value is, mainly because the lower the speed is, the fluctuation of the speed is more capable of sensing the stability of the vehicle; the higher the rotation speed is, the too small value of N can cause the regulation and control of the EGR rate to be too frequent, so that the action advantage of the EGR is reduced.
The values of N in the embodiment of the present application are shown in table 9.
TABLE 9
Engine speed n (rpm) 600 725 850 1000 1200 1400 1600 1800 2000
N 3 3 5 5 6 6 8 8 10
K in the embodiment of the application SpeedDiff The values are shown in Table 10.
Table 10
Figure SMS_36
Figure SMS_37
At this time, if the absolute value |n of the rotational speed difference is detected SpeedDiff I is greater than a first preset value n SpeedDiffM arg in If the time is longer than T1, the EGR rate self-learning state under the idle working condition is the EGR rate downward learning state under the idle working condition.
Preferably, T1 is 0.5s.
At this time, if the absolute value |n of the rotational speed difference is detected SpeedDiff I is greater than a first preset value n SpeedDiffMargin If the time of the engine is longer than T1, the EGR rate is still required to be further reduced, and the EGR rate self-learning state under the idle working condition is the EGR rate downward learning state under the idle working condition, namely the EGR rate self-learning correction factor r under the idle working condition IdleAdpationRation The need for reduction.
Under the current working condition, EGR rate self-learning correction factor r under idle working condition IdleAdpationRatio The update is not learned, and only the learning state at that time is recorded.
Case 2, absolute value of rotational speed difference |n SpeedDiff I is not greater than a first preset value n SpeedDiffM arg in But greater than a second preset value n SpeedDiffM arg in1 Or absolute value of rotation speed difference |n SpeedDiff Absolute value of engine speed difference of not more than the last sampling period
Figure SMS_38
At the time, EGR rate r under idle condition EFRIleAct ive，Final The method comprises the following steps:
r EGRIleActive，Fina ＝r EGRIdleActive，Setpo int ×k SpeedDiff increasing EGR rate at idle after time T2 at rate R1 once absolute value of speed difference |n is detected SpeedDiff I is greater than a first preset value n SpeedDiffM arg in And the EGR rate self-learning state under the idle working condition is the EGR rate downward learning state under the idle working condition.
Preferably, the embodiment R1 is 0.02/10ms.
Specifically, the second presetValue n SpeedDiffM arg in Design accuracy n for engine speed fluctuation SpeedDiff Pr ecision Is 1 times larger than the k.
Namely, the rotational speed fluctuation error of the rotational speed fluctuation below the rotational speed fluctuation design accuracy requirement k1 times of the engine is regulated by the rotational speed control.
Preferably, k1 is 1.2, then embodiment n of the present application SpeedDiffMargin1 At 18rpm.
Absolute value n of rotational speed difference SpeedDi I is not greater than a first preset value n SpeedDiffM arg in But greater than a second preset value n SpeedDiffM arg in1 Or absolute value of rotation speed difference |n SpeedDiff Absolute value of engine speed difference of not more than the last sampling period
Figure SMS_39
And the fluctuation of the rotating speed under the current working condition is weakened. Once the absolute value of the rotational speed difference |d is detected SpeedDiff I is greater than a first preset value n SpeedDiffM arg in The current requirement of further reducing the EGR rate is described that the EGR rate self-learning state under the idle working condition is the EGR rate downward learning state under the idle working condition, namely the EGR rate self-learning correction factor r under the idle working condition IdleAdpationRatio The need for reduction.
If in the process, the absolute value |n of the rotational speed difference is not detected SpeedDiff I is greater than a first preset value n SpeedDiffMargin If the time exceeds T2, the EGR rate still needs to be further reduced, the EGR rate self-learning state under the idle working condition is the EGR rate upward learning state under the idle working condition, namely the EGR rate self-learning correction factor r under the idle working condition IdleAdpationRatio May be increased.
Preferably, embodiment T2 of the present application is 0.5s.
Under the current working condition, EGR rate self-learning correction factor r under idle working condition IdleAdpationRatio The update is not learned, and only the learning state at that time is recorded.
The values of T2 in the examples of the present application are shown in table 11.
TABLE 11
Engine speed n (rpm) 600 725 850 1000 1200 1400 1600 1800 2000
T2(s) 0.4 0.5 0.6 0.7 0.7 0.8 0.9 1 1.3
Case 3, when neither case 1 nor case 2 are satisfied, the EGR rate r under idle conditions EGRIdleActive，Final Is idlingEGR rate r under operating conditions EGRIdleActive，Setop int ；
If the EGR rate self-learning state under the idle working condition in the last sampling period is detected to be the EGR rate upward learning state under the idle working condition, the EGR rate self-learning correction factor r under the idle working condition IdleAdpationRatio Increasing at a rate k 2;
if the EGR rate self-learning state under the idle working condition in the last sampling period is detected to be the EGR rate downward learning state under the idle working condition, the EGR rate self-learning correction factor R under the idle working condition IdleAdpationRatio Decrease at a rate k3, where k2 < |k3|.
The absolute value of the downward learning rate is higher than that of the upward learning rate, so that the occurrence of rotation speed fluctuation under the idle working condition is avoided.
Preferably k2=0.002/10 ms, k3= -0.005/10ms.
Preferably, the last sampling period is the last 10ms sampling period.
Specifically, EGR rate r under idle conditions EGRIdleActive，Final Is limited between a maximum value MAX and a minimum value MIN, wherein the maximum value MAX is determined according to the engine speed n and the load rho, and the minimum value MIN is 0. The maximum value MAX in the embodiment of the present application is shown in table 12.
Table 12
Figure SMS_40
Specifically, the priority of case 1 is higher than the priority of case 2, and the priority of case 2 is higher than the priority of case 3.
FIG. 2 is a logic diagram illustrating one embodiment of a method for controlling a target EGR rate during idle conditions in accordance with the present invention.
The foregoing examples have shown only the preferred embodiments of the invention, which are described in more detail and are not to be construed as limiting the scope of the invention. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention. Accordingly, the scope of protection of the present invention is to be determined by the appended claims.

Claims (10)

1. The target EGR rate control method under the idle working condition is characterized by comprising the following steps of:
step 1, determining an original value r of an EGR rate under idle working conditions EGRIdleActive，raw ：
Figure QLYQS_1
wherein ,rEGRIdleActive，mapped Is the basic value, k, of the original value of the EGR rate SpeedDiff 、k SpeedDerivativeDiff 、k ElectricalLoad 、k Coolant 、k AirTrqSparkTrqDiff 、k CatHeating 、/>
Figure QLYQS_2
A correction factor for the EGR rate of idle speed regulation;
step 2, determining an ideal value r of the EGR rate under the idle working condition EGRIdleActive，Setpoint ：
r EGRIdleActive，Setpoint ＝r EGRIdleActive，raw ×(1+r IdleAdpationRatio )
wherein ,rIdleAdpationRatrio The EGR rate self-learning correction factor is used for the EGR rate self-learning correction factor under the idle working condition;
step 3, determining an EGR rate final value r under the idle working condition according to the EGR rate ideal value under the idle working condition EGRIdleActive，Final 。
2. The method according to claim 1, characterized in that the r is determined based on the engine speed n and the load rho EGRIdleActive，mapped Wherein the load is the in-cylinder fresh air density.
3. The method according to claim 1, characterized in that in step 1, the correction factor of the EGR rate is determined by:
1) According to the engine speed n and the speed difference n between the target speed and the actual speed SpeedDiff Determining the k SpeedDiff ；
The engine speed is unchanged, the larger the speed difference is, the k SpeedDiff The smaller;
the rotation speed difference is unchanged, the higher the rotation speed of the engine is, the k is SpeedDiff The larger;
2) According to the rotation speed difference n speedDiff And a rotational speed difference change rate dn SpeedDiff Determining the k SpeedDerivativeDiff ；
The rotation speed difference is unchanged, the greater the rotation speed difference change rate is, the k SpeedDerivativeDiff The smaller;
the change rate of the rotation speed difference is unchanged, and the larger the rotation speed is, the k is SpeedDerivativeDiff The smaller;
3) Torque ratio of torque according to the engine speed and electrical load to torque of idle gas circuit
Figure QLYQS_3
Determining the k ElectricalLoad ；
The higher the ratio of the torque, the more the engine speed is, the k ElectricalLoad The smaller;
the torque ratio is unchanged, the greater the engine speed, the k ElectricalLoad The larger;
4) Determining the k according to the engine water temperature Coolant ；
5) Determining the k according to the engine speed and the difference between the torque of the idle gas circuit and the torque of the idle fire circuit AirTrqSparkTrqDiff ；
The greater the difference in torque, the greater the torque difference AirTrqSparkTrqDiff The larger;
the torque difference is unchanged, the engineThe greater the rotational speed, the k AirTrqSparkTrqDiff The larger;
6) According to the ignition efficiency r in the catalyst ignition process CatHeatingSparkEff And said engine speed determining said k CatHeating ；
The higher the ignition efficiency, the constant the engine speed, the k CarHeating The larger;
the ignition efficiency is unchanged, the greater the engine speed, the k CayHeating The larger;
7) According to the speed v and the gear Cnt of the vehicle gearbox Gear Determining the said
Figure QLYQS_4
The vehicle speed is unchanged, the larger the gear is, the more the
Figure QLYQS_5
The smaller; />
The gear is unchanged, the greater the vehicle speed is, the more the
Figure QLYQS_6
The larger.
4. A method according to claim 3, wherein in said 2), said rotational speed difference change rate dn SpeedDiff The method comprises the following steps:
Figure QLYQS_7
wherein ,
Figure QLYQS_8
for the rate of change of the rotational speed difference of the last sampling period,/->
Figure QLYQS_9
For the rotational speed difference of the last sampling period, deltat is the sampling period,t c a filter time constant for calculating the rate of change of the rotational speed difference.
5. The method according to claim 1, wherein in the step 2, the self-learning is performed continuously throughout the life cycle of the engine, and the learned value of the EGR rate self-learning correction factor under the idle condition is stored in the EEPROM of the controller after power-down; when the vehicle is off line, the EGR rate self-learning correction factor r under the idle working condition IdleAdpati onRatio Is 0.
6. The method according to claim 3, wherein the step 3 includes three cases:
case 1, the rotational speed difference n SpeedDiff Absolute value of |n SpeedDiff I is greater than a first preset value n SpeedDiffMargin And absolute value of the rotation speed difference |n SpeedDiff Absolute value of engine speed difference that is larger than last sampling period
Figure QLYQS_10
At the time, the EGR rate r under the idle working condition EGRIdleActive，Final The method comprises the following steps:
r EGRIdleActive，Fina ＝r EGRIdleActive，Setpoint xk SpeedDiff ；
at this time, if the absolute value |n of the rotational speed difference is detected SpeedDiff I is larger than the first preset value n SpeedDiffMargin If the time is longer than T1, the EGR rate self-learning state under the idle working condition is the EGR rate downward learning state under the idle working condition;
under the current working condition, the EGR rate self-learning correction factor r under the idle working condition IdleAdpationRatio The learning state is only recorded when the updating is not learned;
case 2, absolute value of the rotational speed difference |n SpeedDiff I is not greater than the first preset value n SpeedDiffMargin But greater than a second preset value n SpeedDiffMarginl Or the rotational speed differenceAbsolute value of |n SpeedDiff I is not greater than the absolute value of the engine speed difference of the last sampling period
Figure QLYQS_11
At the time, the EGR rate r under the idle working condition EGRIdleActive，Final The method comprises the following steps: r is (r) EGRIdleActive，Fina ＝r EGRIdleActive，Setpoint ×k SpeedDiff Increasing the EGR rate at the idle condition at a rate R1 after a time T2, once the absolute value of the speed difference |n is detected SpeedDiff I is larger than the first preset value n SpeedDiffargin The EGR rate self-learning state under the idle working condition is an EGR rate downward learning state under the idle working condition;
if in the process the absolute value of the rotational speed difference |n is not detected SpeedDiff I is larger than the first preset value n SpeedDiffMargin If the time exceeds the T2, the EGR rate self-learning state under the idle working condition is an EGR rate upward learning state under the idle working condition;
under the current working condition, the EGR rate self-learning correction factor r under the idle working condition IdleAdpationRatio The learning state is only recorded when the updating is not learned;
case 3, when neither case 1 nor case 2 are satisfied, the EGR rate r under the idle condition EGRIdleActive，Final For the EGR rate r under the idle condition EGRIdleActive，Setpoint ；
If the EGR rate self-learning state under the idle working condition in the last sampling period is detected to be the EGR rate upward learning state under the idle working condition, the EGR rate self-learning correction factor r under the idle working condition is detected IdleAdpationRatio Increasing at a rate k 2;
if the EGR rate self-learning state under the idle working condition in the last sampling period is detected to be the EGR rate downward learning state under the idle working condition, the EGR rate self-learning correction factor r under the idle working condition is detected IdleAdpationRatio Decrease at a rate k3, where k2 < |k3|.
7. According to the weightsThe method for controlling a target EGR rate under idle conditions as recited in claim 6, wherein the EGR rate r under idle conditions EGRIdleActive，Final Is limited between a maximum value MAX and a minimum value MIN, wherein the maximum value MAX is determined according to the engine speed n and the load rho, and the minimum value MIN is 0.
8. The method according to claim 6, characterized in that in the case 1, the k is SpeedDiff From the engine speed n and a speed difference n between the target speed and the actual speed SpeedDiff Co-determination of the rotational speed difference n SpeedDiff Taking the maximum value and the minimum value of the rotation speed difference before the last N sampling periods, wherein the smaller the rotation speed of the engine is, the smaller the N value is, the larger the rotation speed of the engine is, and the larger the N value is.
9. The method according to claim 6, characterized in that in the case 2, the second preset value n SpeeddDiffMarginl Design accuracy n for engine speed fluctuation SpeedDiffPrecision Is 1 times larger than the k.
10. The method according to claim 6, characterized in that the priority of the case 1 is higher than the priority of the case 2, and the priority of the case 2 is higher than the priority of the case 3.
CN202211528641.5A 2022-11-30 2022-11-30 Target EGR rate control method under idle working condition Pending CN116044586A (en)

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