CN115680915A - Method, device, equipment and storage medium for designing minimum EGR rate - Google Patents
Method, device, equipment and storage medium for designing minimum EGR rate Download PDFInfo
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- 238000000034 method Methods 0.000 title claims abstract description 43
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 65
- 239000000446 fuel Substances 0.000 claims abstract description 54
- 238000002485 combustion reaction Methods 0.000 claims abstract description 38
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 19
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Abstract
The invention discloses a method, a device, equipment and a storage medium for designing a minimum EGR rate, wherein the method comprises the following steps: determining a base minimum EGR rate based on engine speed and load; and determining an original minimum EGR rate as a minimum EGR rate according to the atmospheric pressure, the water temperature, the engine combustion times, the atmospheric temperature, the real-time engine water temperature, the engine starting water temperature, the engine air inlet temperature, the mass flow of fuel steam entering a cylinder from a carbon tank, the engine rotating speed and the basic minimum EGR rate. Has the advantages that: the EGR can be closed when the EGR rate is extremely low, so that the influence on the stability of an EGR system is avoided, and meanwhile, the software development cost can be lower.
Description
Technical Field
The invention relates to the technical field of engines, in particular to a method, a device, equipment and a storage medium for designing a minimum EGR rate.
Background
Research shows that the EGR system has certain advantages in improving emission, reducing oil consumption and improving anti-knock capability. EGR waste gas reduces combustion temperature, avoids knocking, and inhibits ignition advance angle delay. The control actuator may oscillate due to the low system hysteresis EGR rate, even the EGR system is unstable; and if the EGR rate is too low, great requirements are made on the control capability of the EGR system; even too low an EGR rate may not exhibit its advantages. Based on the method, the design method of the minimum EGR rate is provided, the EGR is closed when the EGR rate is extremely low, the influence on the stability of an EGR system is avoided, and meanwhile, the software development cost can be lower.
Disclosure of Invention
In view of the above-identified deficiencies in the art or needs for improvements, it is an object of the present invention to provide a method, apparatus, device and storage medium for minimum EGR rate design.
In order to achieve the purpose, the invention adopts the following technical scheme:
in a first aspect, a method for designing a minimum EGR rate includes the steps of:
determining a base minimum EGR rate based on engine speed and load;
and determining an original minimum EGR rate as a minimum EGR rate according to the atmospheric pressure, the water temperature, the engine combustion times, the atmospheric temperature, the real-time engine water temperature, the engine starting water temperature, the engine air inlet temperature, the mass flow of fuel steam entering a cylinder from a carbon tank, the engine rotating speed and the basic minimum EGR rate.
In one embodiment, the step of determining and using as the minimum EGR rate the original minimum EGR rate based on atmospheric pressure, water temperature, engine combustion times, atmospheric temperature, engine real-time water temperature, engine starting water temperature, engine intake air temperature, mass and flow of fuel vapor from the canister into the cylinder, engine speed, and the base minimum EGR rate comprises:
determining a first multiplication factor r according to the atmospheric pressure and the water temperature 1 ；
Determining a second multiplication factor r according to the combustion times of the engine and the atmospheric temperature 2 ；
Determining a third multiplication factor r according to the real-time water temperature of the engine and the starting water temperature of the engine 3 ；
Determining a fourth multiplication factor r according to the real-time water temperature and the air inlet temperature of the engine 4 ；
Determining a fifth multiplication factor r according to the mass and the flow of fuel steam entering the cylinder from the carbon tank and the rotating speed of the engine 5 。
In one embodiment, the original minimum EGR rate r EGRVehicleMin Obtained according to the following formula:
r EGRVehicleMin ＝r EGRBenchMin ·(1+r 1 )·(1+r 2 )·(1+r 3 )·(1+r 4 )·(1+r 5 )；
wherein r is EGRBenchMin Representing the base minimum EGR rate.
In one embodiment, the method for designing the minimum EGR rate further comprises self-learning updating when the engine operating conditions are stable:
after the updating stage of self-learning updating is determined, the target average value rho of the intake density of the fresh air entering the cylinder under the current working condition DsrdAvg Average value rho of intake density filtered value of fresh air actually entering cylinder ActFilterAvg Target air-fuel ratio r DsrdAFRavg And the average value r of the filtered values of the actual air-fuel ratios AFRFilterAvg Updating the initial value of the learning value;
determining a new minimum EGR rate learning value according to the learning value initial value and the last minimum EGR rate learning value under the same working condition;
and determining a final minimum EGR rate according to the current original minimum EGR rate and the new minimum EGR rate learning value.
In one embodiment, after the determination enters the self-learning updating stage, the target average value rho of the intake density of the fresh air entering the cylinder according to the current working condition DsrdAvg Average value rho of intake density filtered value of fresh air actually entering cylinder ActFilterAvg Target air-fuel ratio r DsrdAFRavg And the average value r of the filtered values of the actual air-fuel ratios AFRFilterAvg The step of updating the initial value of the learned value includes:
according to the current working conditionTarget average value rho of intake density of fresh air entering cylinder at lower part DsrdAvg And the average value rho of the intake density filtered value of the fresh air actually entering the cylinder ActFilterAvg Determining a first judgment value;
according to the target air-fuel ratio r DsrdAFRavg And the average value r of the filtered values of the actual air-fuel ratios AFRFilterAvg Determining a second judgment value;
and determining the initial value of the learning value according to the first judgment value and the second judgment value.
In one embodiment, the first determination value C 1 Obtained according to the following formula:
the second judgment value C 2 Is determined according to the following formula:
in one embodiment, before entering the self-learning update phase, the method further comprises the following steps:
determining that an activation condition is satisfied based on the engine and the EGR system;
and entering a stabilization stage after the activation condition is met, and entering an updating stage when the stabilization stage meets a duration condition and the self-learning times are not updated.
In a second aspect, a minimum EGR rate designing apparatus includes:
a first module to determine a base minimum EGR rate based on engine speed and load;
and the second module is used for determining an original minimum EGR rate according to the atmospheric pressure, the water temperature, the engine combustion times, the atmospheric temperature, the engine starting water temperature, the engine air inlet temperature, the mass flow of fuel steam entering the cylinder from the carbon tank, the engine rotating speed and the basic minimum EGR rate and taking the original minimum EGR rate as the minimum EGR rate.
In a third aspect, an electronic device includes a processor and a memory, the processor and the memory being interconnected;
the memory is used for storing a computer program;
the processor is configured to execute the minimum EGR rate design method as described above when the computer program is invoked.
In a fourth aspect, a computer-readable storage medium stores a computer program executed by a processor to implement the minimum EGR rate design method described above.
The invention has the beneficial effects that:
for the design method of the minimum EGR rate, determining a basic minimum EGR rate according to the rotating speed and the load of the engine; according to the method, the original minimum EGR rate is determined and used as the minimum EGR rate according to the atmospheric pressure, the water temperature, the engine combustion times, the atmospheric temperature, the real-time water temperature of the engine, the engine starting water temperature, the engine air inlet temperature, the mass flow of fuel steam entering the cylinder from the carbon tank, the engine rotating speed and the basic minimum EGR rate, the EGR can be closed when the EGR rate is extremely low, the influence on the stability of an EGR system is avoided, and meanwhile, the software development cost can be lowered.
Determining a basic minimum EGR rate according to the engine speed and the load for a minimum EGR rate design device; according to the method, the original minimum EGR rate is determined and used as the minimum EGR rate according to the atmospheric pressure, the water temperature, the engine combustion times, the atmospheric temperature, the real-time water temperature of the engine, the engine starting water temperature, the engine air inlet temperature, the mass flow of fuel steam entering the cylinder from the carbon tank, the engine rotating speed and the basic minimum EGR rate, the EGR rate can be closed when the EGR rate is extremely low, the influence on the stability of an EGR system is avoided, and meanwhile, the software development cost can be lowered.
For the electronic device, determining a base minimum EGR rate based on engine speed and load; according to the method, the original minimum EGR rate is determined and used as the minimum EGR rate according to the atmospheric pressure, the water temperature, the engine combustion times, the atmospheric temperature, the real-time water temperature of the engine, the engine starting water temperature, the engine air inlet temperature, the mass flow of fuel steam entering the cylinder from the carbon tank, the engine rotating speed and the basic minimum EGR rate, the EGR can be closed when the EGR rate is extremely low, the influence on the stability of an EGR system is avoided, and meanwhile, the software development cost can be lowered.
Determining, for the computer readable storage medium, a base minimum EGR rate based on engine speed and load; according to the method, the original minimum EGR rate is determined and used as the minimum EGR rate according to the atmospheric pressure, the water temperature, the engine combustion times, the atmospheric temperature, the real-time water temperature of the engine, the engine starting water temperature, the engine air inlet temperature, the mass flow of fuel steam entering the cylinder from the carbon tank, the engine rotating speed and the basic minimum EGR rate, the EGR can be closed when the EGR rate is extremely low, the influence on the stability of an EGR system is avoided, and meanwhile, the software development cost can be lowered.
Additional aspects and advantages of the present application will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the present application.
Drawings
The foregoing and/or additional aspects and advantages of the present application will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
FIG. 1 is a schematic structural diagram of a low-pressure EGR system provided in the present embodiment;
fig. 2 is a flowchart illustrating a method for designing the minimum EGR rate according to the present embodiment.
FIG. 3 is a schematic structural view of a minimum EGR rate designing apparatus provided in the present embodiment;
fig. 4 is a schematic structural diagram of the electronic device of the present embodiment.
Detailed Description
The present invention will be described in further detail with reference to the drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.
In the description of the present invention, unless expressly stated or limited otherwise, the terms "connected," "connected," and "fixed" are to be construed broadly, e.g., as meaning permanently connected, removably connected, or integral to one another; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or may be connected through the use of two elements or the interaction of two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
As used herein, the singular forms "a", "an", "the" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
It will be understood by those within the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the prior art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
The invention provides a design method of a minimum EGR rate, which is applied to a low-pressure EGR system.
Fig. 1 is a schematic diagram of the configuration of the low-pressure EGR system provided in this embodiment, and as shown in fig. 1, the system includes an air filter, a supercharger compressor, a throttle valve, an engine, a supercharger turbine, a catalyst, a particulate trap, an EGR cooler, an EGR valve, an EGR temperature sensor, an EGR differential pressure sensor, a flow meter, and a linear oxygen sensor, and it should be noted that the linear oxygen sensor is replaced with an integrated temperature and pressure sensor.
The supercharger compressor is used for compressing fresh air for supercharging.
The supercharger turbine controls the working efficiency of the turbine by controlling the opening of a waste gas bypass valve of the supercharger, thereby realizing different supercharging capacities.
The low-pressure EGR system has the following added parts compared with the non-low-pressure EGR system: EGR cooler, EGR temperature sensor, EGR valve, EGR differential pressure sensor, mixing valve, flow meter and oxygen sensor.
A flow meter is mounted between the air filter and the mixing valve for sensing the flow of fresh air into the engine.
The mixing valve is used for adjusting the pressure at the outlet of the EGR valve, improving the pressure difference at two ends of the EGR valve and improving the EGR rate.
An oxygen sensor is installed between the compressor and the throttle valve and near the throttle valve, and the oxygen sensor is used for detecting the flow of the mixture entering the cylinder.
The EGR cooler is used to cool the exhaust gas, facilitating an increase in the exhaust gas flow and a decrease in the exhaust gas temperature.
The EGR valve acts as a throttle, controlling the flow of exhaust gas into the cylinder.
The EGR temperature sensor is used to detect the temperature of exhaust gas entering the EGR valve.
The EGR differential pressure sensor is used to detect a difference in exhaust gas pressure between both sides of EGR.
When the engine enters an EGR rate closed-loop control activation state, the EGR rate control adopts PID control.
Fig. 2 is a flowchart illustrating a method for designing the minimum EGR rate according to the present embodiment.
As shown in FIG. 2, the method includes S100, determining a base minimum EGR rate based on engine speed and load.
It should be noted that the basic minimum EGR rate is obtained by calibrating the engine on the bench, the calibration is based on the fact that the EGR rate is infinitely reduced under the working condition that the EGR system is started (until the fluctuation of the engine speed is not less than ± 30rpm under the steady-state working condition, or the fluctuation of the actual opening degree of the EGR valve exceeds ± 1.5%, the EGR rate is stopped to be continuously reduced, and the current EGR rate is recorded), and by comparing the no EGR rate and the previously recorded EGR rate under the same working condition, if the EGR rate is started to improve the oil consumption by not more than 0.2%, the minimum EGR rate is increased until the EGR rate is started to improve the oil consumption by more than 0.2%, and the EGR rate at this time is taken as the minimum EGR rate.
It was determined according to the above test method that the co-extraction was based on engine speed and load (intake air density of fresh air into the cylinder), as shown in table 1.
TABLE 1
It should be noted that the basic minimum EGR rate equal to 0 in table 1 represents that the EGR system itself is not activated under the operating condition, which is partially determined by engine combustion stability, knocking, etc., and the basic minimum EGR rate equal to 0 represents the minimum EGR rate of the EGR system under the operating condition.
And step S200 is carried out after the step S100, and the original minimum EGR rate is determined and used as the minimum EGR rate according to the atmospheric pressure, the water temperature, the engine combustion times, the atmospheric temperature, the real-time engine water temperature, the engine starting water temperature, the engine air inlet temperature, the mass flow of fuel steam entering a cylinder from a carbon tank, the engine rotating speed and the basic minimum EGR rate.
Specifically, step S200 includes:
determining a first multiplication factor r according to the atmospheric pressure and the water temperature 1 . It can be understood that the lower the atmospheric pressure or the lower the water temperature, i.e. the leaner the air or the lower the mixture temperature/the poorer the atomization effect, the poorer the combustion stability of the engine is caused, and the minimum EGR rate needs to be increased to reduce the influence on the combustion stability of the engine and avoid the abnormal shaking of the engine.
Determining a second multiplication factor r according to the combustion times of the engine and the atmospheric temperature 2 . The number of engine combustion is the sum of the number of ignition times of each cylinder from the start of the engine.
It can be understood that the smaller the number of combustion or the lower the atmospheric temperature, the worse the engine combustion stability, and the higher the minimum EGR rate is required to reduce the influence on the engine combustion stability and avoid the occurrence of the engine abnormal vibrations.
Determining a third multiplication factor r according to the real-time water temperature of the engine and the starting water temperature of the engine 3 . It can be understood that the lower the real-time water temperature or the lower the engine starting water temperature, the worse the engine combustion stability, and the higher the minimum EGR rate is required to reduce the influence on the engine combustion stability and avoid the occurrence of engine abnormal judder.
Determining a fourth multiplication factor r according to the real-time water temperature and the air inlet temperature of the engine 4 . It can be understood that the lower the real-time water temperature or the lower the engine intake temperature, the worse the engine combustion stability, and the need to increase the minimum EGR rate to reduce the impact on the engine combustion stability and avoid the occurrence of abnormal engine shake.
Determining a fifth multiplication factor r according to the mass and the flow of fuel steam entering the cylinder from the carbon tank and the rotating speed of the engine 5 . It can be appreciated that the lower the engine speed, the worse the engine combustion stability if the more mass flow of fuel vapor from the canister into the cylinder, the higher the minimum EGR rate needed to reduce the impact on engine combustion stability and avoid engine shudder.
The first, second, third, fourth and fifth multiplication factors aim to identify the aim of improving the combustion stability in the EGR control process according to the current working condition of the engine; the first multiplication factor to the fifth multiplication factor are determined by adopting the prior technical scheme based on the conception when the working condition of the engine is poor (such as the temperature pressure signal is too small, the combustion of the engine is poor, the flow interference of a carbon tank and the like, the minimum EGR rate is required to be improved to improve the combustion stability, and the combustion condition of the engine is better after the temperature is increased to reduce the minimum EGR rate to improve the EGR benefit).
All five multiplication factors (all values are values greater than or equal to 1) are determined by ensuring that the engine combustion stability evaluation index COV is within ± 3%.
Original minimum EGR Rate r EGRVehicleMin Obtained according to the following formula:
r EGRVehicleMin ＝r EGRBenchMin ·(1+r 1 )·(1+r 2 )·(1+r 3 )·(1+r 4 )·(1+r 5 )；
wherein r is EGRBenchMin Indicating a base minimum EGR rate.
After the step S200, self-learning updating of the minimum EGR rate is carried out when the working condition of the engine is stable so as to ensure the accuracy of self-learning.
In this embodiment, the self-learning activation condition needs to satisfy:
1. the engine is in a running state;
the EGR system is in a closed-loop control activation state;
3. the difference between the current actual EGR rate and the minimum EGR rate (if the actual EGR rate is not learned, the original minimum EGR rate of the whole vehicle is obtained, and if the actual EGR rate is learned, the learned minimum EGR rate is obtained) is not more than a preset range, and the difference is +/-0.02% in the embodiment;
4. the difference between the actual EGR rate and the target EGR rate is not more than the preset range, and the example is plus or minus 1 percent
5. The carbon tank is not opened;
6. the engine speed is within a certain range, 600rpm to 5900rpm is taken in the example, the fluctuation of the engine speed entering the ignition angle self-learning of the EGR rate is small, and +/-15 rpm is taken in the example;
7. the load (the intake density of fresh air entering a cylinder) is within a certain range, 200mgpl to 3000mgpl is taken in the example, and the self-learning load fluctuation of the ignition angle of the EGR entering rate is smaller, and +/-20 mgpl is taken in the example;
8. the actual EGR rate is in a certain range, the fluctuation of the actual EGR rate entering the minimum EGR rate self-learning is small, and the actual EGR rate is +/-1% in the embodiment;
9. the engine water temperature is in a certain range (0 ℃ to 100 ℃ is taken in the example), and the fluctuation of the actual EGR rate entering the ignition angle self-learning of the EGR rate is smaller, and +/-2 ℃ is taken in the example. (ii) a
10. The intake air temperature is in a certain range (30 ℃ to 80 ℃ in the example), and the fluctuation of the actual EGR rate entering the ignition angle self-learning of the EGR rate is small, and +/-1.5 ℃ is taken in the example. (ii) a
11. The deviation between the target air inlet VVT angle and the actual air outlet VVT angle is within a preset range, and in the embodiment, the deviation is +/-0.5 degrees;
12. the deviation between the target exhaust VVT angle and the actual exhaust VVT angle is within a preset range, and the angle is +/-0.5 degrees in the example;
13. the fluctuation in the firing angle efficiency was small, and. + -. 0.05 was taken in this example.
14. No knocking and pre-ignition.
15. The fluctuation of atmospheric pressure is small, and the example takes +/-0.02 kPa.
16. The heating of the oxygen sensor is finished;
17. the fluctuation of the intake density of the fresh air entering the cylinder is small, and the value of +/-10 mgpl is taken in the example
18. The difference between the intake density of the fresh air entering the target cylinder and the intake density of the fresh air entering the actual cylinder does not exceed a preset range, and the intake density of the fresh air entering the target cylinder is +/-15 mgpl;
19. the target air-fuel ratio fluctuation is small, and the example is +/-0.08;
20. the difference between the target air-fuel ratio and the actual air-fuel ratio is not more than a preset range, and the example is +/-0.1;
21. no fuel injection system or intake system-related parts or functional faults occur.
If either condition is not met, the step of the method of designing a minimum EGR rate will be stopped if the activation condition is deemed not to be met.
And after the activation condition is met, the user is considered to enter a stabilization stage, and the stabilization stage aims to ensure the stability and reliability of subsequent self-learning. The stabilization phase maintaining time exceeds T0 (in this embodiment, T0 is set to 5 s), and meanwhile, the minimum EGR rate is not updated in the T1 period, the activation phase is entered.
In the activation phase, the sum of engine speed, intake air temperature, water temperature, intake VVT angle, ignition efficiency, actual EGR rate, target intake cylinder fresh air intake density, actual intake cylinder fresh air intake density, target air-fuel ratio, and actual air-fuel ratio are added up for a certain time T2 (3 s in this embodiment).
Where actual cylinder intake is freshFiltered value rho of air intake density ActFilter Calculated according to the following formula:
rho ActFilter ＝K Rho ×[rho ActRaw (N)-rho ActFilter (N-1)]+rho ActFilter (N-1)；
wherein rho ActRaw (N) actual intake cylinder fresh air intake density raw value, rho, for the Nth sampling period ActFilter Represents the actual intake cylinder fresh air intake density after the first-order low-pass filtering (i.e., the actual intake cylinder fresh air intake density filtered value), rho ActFilter (N-1) is an actual intake cylinder fresh air intake density filtered value of the N-1 sampling period, N =1,2,3 \8230. Note that rho ActFilter (0) Representing the actual intake cylinder fresh air intake density raw value just as it entered the activation phase; the sampling period interval is set to 10ms.
K Rho Is a coefficient which is filtered according to the number m of engine cylinders, the engine speed n and the fresh air quantity k Rho Determined according to the following formula:
K Rho ＝m·n·k Rho /4000；
the number of cylinders of the engine is 4 in the example, the rotating speed of the engine is 1000rpm Rho Taking 0.02, the purpose of the setting is to normalize the treatment, under different cylinder numbers and rotating speeds, the special calibration is not needed, only a 4-cylinder machine and k with the rotating speed of 1000rpm need to be calibrated Rho Thereby reducing calibration test work.
Actual air-fuel ratio filter value r AFRFilter Obtained according to the following formula:
r AFRFilter (N)＝K AFR ·[r AFRRaw (N)-r AFRFilter (N-1)]+r AFRFilter (N-1)；
wherein r is AFRRaw For actual air-fuel ratio original value, r AFRRaw (N) is the actual original value of the air-fuel ratio in the Nth sampling period, r AFRFilter Is the actual air-fuel ratio after the first-order low-pass filtering (i.e. the actual air-fuel ratio filtering value), r AFRFilter (N) is the actual air-fuel ratio filtered value of the Nth sampling period, r AFRFilter (N-1) is an actual air-fuel ratio filter value of the N-1 th sampling period, N =1,2,3 8230; r AFRFilter (0) Is the original value of the actual air-fuel ratio just before entering the self-learning activation stage, K AFR As a coefficient, K in this example AFR ＝m·n·k Afr /4000, wherein k Afr Fresh air intake density filtered value rho depending on actual intake of engine into cylinder ActFilter 。
In this embodiment, when the filter values of the intake density of fresh air actually entering the cylinder of the engine are 300, 500, 700, 1000, 1500, 2000, 2500 and 3000, respectively, k corresponds to k Afr 0.15, 0.17, 0.18, 0.2, 0.21, 0.23, 0.24, 0.25, respectively. In the present embodiment, ka fr is set to 0.023.
And after T2, entering an updating stage. After the update phase, the design method further comprises the steps of:
according to the target average value rho of intake density of fresh air entering the cylinder under the current working condition DsrdAvg And the average value rho of the intake density filtered value of the fresh air actually entering the cylinder ActFilterAvg Target air-fuel ratio r DsrdAFRavg And the average value r of the filtered values of the actual air-fuel ratios AFRFilterAvg Updating the initial value of the learning value;
determining a new minimum EGR rate learning value according to the learning value initial value and the last minimum EGR rate learning value under the same working condition;
and determining a final minimum EGR rate according to the current original minimum EGR rate and the new minimum EGR rate learning value.
The minimum EGR rate for each operating condition is stored in the non-volatile memory EEPROM. There will be an initial default value in EEPROM, which is 1. The stored value in the EEPROM is updated after the minimum EGR rate self-learning is completed.
The number of times (1 is added after each time of satisfaction) of the self-learning stabilization stage under the corresponding working condition does not exceed the preset number of times, and when the number of times is 30, the minimum EGR rate learning value is maintained as the last learning value. Otherwise, updating is carried out.
The engine speed after the time T2 of the update phase (80 s in this embodiment)Mean value n Avg Intake air temperature average value T ManAvg Average value of water temperature T coolantAvg Intake VVT angle average phi IntakeVVTAvg Average value of ignition efficiency r SparkEffAg Average intake density rho of fresh air of target intake cylinder DsrdAvg Target air-fuel ratio r DsrdAFRAvg And the average value rho of the intake density filtered value of the fresh air actually entering the cylinder ActFilterAvg Average value r of filtered value of actual air-fuel ratio AFRFilterAvg Actual EGR Rate average value r ActEGRAvg And stored in the EEPROM.
C 1 Is determined according to the following formula:
C 2 is determined according to the following formula:
if C is 1 And C 2 Not less than 0.05, the initial value r of the learning value EGRMinAdaptRaw Is 1.02.
If C is present 1 Not less than 0.05,C 2 Between 0.02 and 0.05, the initial value r of the learning value EGRMinAdaptRaw Is 1.01.
If C is 1 Between 0.02 and 0.05, C 2 Not less than 0.05, the initial value r of the learning value EGRMinAdaptRaw Was 1.05.
If C is 1 And C 2 All are between 0.02 and 0.05, then the initial value r of the learning value EGRMinAdaptRaw Was 1.02.
If C is 1 And C 2 If the value is not more than 0.02, the initial value r of the learning value is EGRMinAdaptRaw Is 1.02.
The purpose of the design is that after the EGR rate is introduced, the air quantity and the air-fuel ratio fluctuate greatly, and the minimum EGR rate needs to be further improved when the dynamic property and the emission influence are large; if the air flow fluctuation is increased, but the air-fuel ratio is increased slightly, the air flow is disturbed greatly after the EGR rate is introduced, the influence on the dynamic property is poor, and the minimum EGR rate needs to be increased in a moderate way; if the air-fuel ratio fluctuation is increased, but the air flow fluctuation is smaller, the interference on the air flow after the EGR rate is introduced is smaller, the influence on the dynamic property is weaker, the minimum EGR rate needs to be properly improved at the moment, the influence on the emission is avoided, and the emission can be further protected through an exhaust system, so that the improvement of the minimum EGR rate is not larger than the improvement of the minimum EGR rate with the larger air flow fluctuation at the moment; if the introduction of EGR has less influence on both the air quantity and the air-fuel ratio fluctuation, the minimum EGR rate does not need to be increased.
Note that, in addition to the above, the initial value r of the learning value EGRMinAdaptRaw Is 1.
The final minimum EGR rate learned value rEGRMinAdapt And limiting it to within the minimum 1 and maximum 1.08 learned values (to avoid exceeding the target EGR rate) yields:
r EGRMinAdapt ＝r EGRMinAdapt (z)×(1+r EGRMinAdaptRaw ) Wherein r is EGRMinAdapt (z) is the minimum EGR rate learning value learned in the same operating condition last time, and the first default value of the minimum EGR rate learning value is 1.
Minimum EGR rate learned value r finally learned EGRMinFinal After calculation according to the following formula, storing the data into the corresponding working condition of the EEPROM:
r EGRMinFinal ＝r EGRVehicleMin ×(1+r EGRMinAdapt )。
the above completes the entire description of the design method of the minimum EGR rate.
According to the design method of the minimum EGR rate, the basic minimum EGR rate is determined according to the rotating speed and the load of the engine; according to the atmospheric pressure, the water temperature, the engine combustion times, the atmospheric temperature, the engine starting water temperature, the engine air inlet temperature, the fuel steam mass flow of the carbon tank entering the cylinder, the engine rotating speed and the basic minimum EGR rate, the original minimum EGR rate is determined and used as the minimum EGR rate, the EGR can be closed when the EGR rate is extremely low, the influence on the stability of an EGR system is avoided, and meanwhile, the software development cost can be lowered.
The present embodiment also provides a minimum EGR rate designing apparatus.
Fig. 3 is a schematic structural diagram of the minimum EGR rate designing apparatus provided in the present embodiment, and referring to fig. 3, the minimum EGR rate designing apparatus includes a first module and a second module.
A first module determines a base minimum EGR rate based on engine speed and load.
The second module is used for determining an original minimum EGR rate according to atmospheric pressure, water temperature, engine combustion times, atmospheric temperature, engine real-time water temperature, engine starting water temperature, engine air inlet temperature, mass flow of fuel steam entering a cylinder from a carbon tank, engine rotating speed and the basic minimum EGR rate and taking the original minimum EGR rate as the minimum EGR rate.
It should be noted that the minimum EGR rate designing apparatus provided in the present embodiment may be a computer program (including program code) running in a computer device, for example, the minimum EGR rate designing apparatus is an application software; the minimum EGR rate design means may be used to perform the corresponding steps in the above method provided by the embodiments of the present application.
In some possible implementations, the design apparatus for providing the minimum EGR rate in this embodiment may be implemented by combining hardware and software, and the design apparatus for providing the minimum EGR rate in this embodiment may be a processor in the form of a hardware decoding processor, which is programmed to perform the design method for providing the minimum EGR rate in this embodiment, for example, the processor in the form of a hardware decoding processor may be implemented by one or more Application Specific Integrated Circuits (ASICs), digital Signal Processors (DSPs), programmable Logic Devices (PLDs), complex Programmable Logic Devices (CPLDs), field Programmable Gate Arrays (FPGAs), or other electronic components.
In some possible embodiments, the design device for providing the minimum EGR rate according to this embodiment may be implemented in software, which may be software in the form of programs and plug-ins, and includes a series of modules, such as a first module and a second module, to implement the design method for providing the minimum EGR rate according to this embodiment.
The minimum EGR rate design device provided by the embodiment determines a basic minimum EGR rate according to the rotating speed and the load of the engine; according to the method, the original minimum EGR rate is determined and used as the minimum EGR rate according to the atmospheric pressure, the water temperature, the engine combustion times, the atmospheric temperature, the real-time water temperature of the engine, the engine starting water temperature, the engine air inlet temperature, the mass flow of fuel steam entering the cylinder from the carbon tank, the engine rotating speed and the basic minimum EGR rate, the EGR rate can be closed when the EGR rate is extremely low, the influence on the stability of an EGR system is avoided, and meanwhile, the software development cost can be lowered.
An embodiment of the present application further provides an electronic device, fig. 4 is a schematic structural diagram of the electronic device of the present embodiment, and as shown in fig. 4, the electronic device 1000 in the present embodiment may include: the processor 1001, the network interface 1004, and the memory 1005, in addition, the electronic device 1000 may further include: a user interface 1003, and at least one communication bus 1002. The communication bus 1002 is used to implement connection communication among these components. The user interface 1003 may include a Display screen (Display) and a Keyboard (Keyboard), and the optional user interface 1003 may also include a standard wired interface and a standard wireless interface. The network interface 1004 may optionally include a standard wired interface, a wireless interface (e.g., a WI-FI interface). The memory 1004 may be a high-speed RAM memory or a non-volatile memory, such as at least one disk memory. The memory 1005 may alternatively be at least one memory device located remotely from the processor 1001. As shown in fig. 4, the memory 1005, which is a kind of computer-readable storage medium, may include therein an operating system, a network communication module, a user interface module, and a device control application program.
In the electronic device 1000 shown in fig. 4, the network interface 1004 may provide network communication functions; the user interface 1003 is an interface for providing input to a user; and the processor 1001 may be used to invoke a device control application stored in the memory 1005 to implement:
determining a base minimum EGR rate based on engine speed and load;
and determining an original minimum EGR rate as a minimum EGR rate according to the atmospheric pressure, the water temperature, the engine combustion times, the atmospheric temperature, the real-time engine water temperature, the engine starting water temperature, the engine air inlet temperature, the mass flow of fuel steam entering a cylinder from a carbon tank, the engine rotating speed and the basic minimum EGR rate.
It should be understood that in some possible embodiments, the processor 1001 may be a Central Processing Unit (CPU), and the processor may be other general-purpose processors, DSPs, ASICs, FPGAs, or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, or the like. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like. The memory may include both read-only memory and random access memory, and provides instructions and data to the processor. The portion of memory may also include non-volatile random access memory. For example, the memory may also store device type information.
In a specific implementation, the electronic device 1000 may execute the implementation manners provided in the steps in fig. 2 through the built-in functional modules, which may specifically refer to the implementation manners provided in the steps, and are not described herein again.
An embodiment of the present application further provides a computer-readable storage medium, where a computer program is stored in the computer-readable storage medium, and is executed by a processor to implement the method provided in each step in fig. 2, which may specifically refer to the implementation manner provided in each step, and is not described herein again.
The computer readable storage medium may be an internal storage unit, such as a hard disk or a memory of an electronic device, of any of the foregoing embodiments, which provides the design method of the minimum EGR rate. The computer readable storage medium may also be an external storage device of the electronic device, such as a plug-in hard disk, a Smart Memory Card (SMC), a Secure Digital (SD) card, a flash card (flash card), and the like, which are provided on the electronic device. The computer readable storage medium may further include a magnetic disk, an optical disk, a read-only memory (ROM), a Random Access Memory (RAM), and the like. Further, the computer readable storage medium may also include both an internal storage unit and an external storage device of the electronic device. The computer-readable storage medium is used for storing the computer program and other programs and data required by the electronic device. The computer readable storage medium may also be used to temporarily store data that has been output or is to be output.
Embodiments of the present application provide a computer program product or computer program comprising computer instructions stored in a computer readable storage medium. The processor of the electronic device reads the computer instructions from the computer-readable storage medium, and the processor executes the computer instructions to cause the computer device to perform the method provided by the steps of fig. 2.
It should be understood that, although the steps in the flowcharts of the figures are shown in order as indicated by the arrows, the steps are not necessarily performed in order as indicated by the arrows. The steps are not performed in the exact order shown and may be performed in other orders unless explicitly stated herein. Moreover, at least a portion of the steps in the flow chart of the figure may include multiple sub-steps or multiple stages, which are not necessarily performed at the same time, but may be performed at different times, which are not necessarily performed in sequence, but may be performed alternately or alternately with other steps or at least a portion of the sub-steps or stages of other steps.
The foregoing is only a partial embodiment of the present application, and it should be noted that, for those skilled in the art, several modifications and decorations can be made without departing from the principle of the present application, and these modifications and decorations should also be regarded as the protection scope of the present application.
Claims (10)
1. A method of designing a minimum EGR rate, comprising the steps of:
determining a base minimum EGR rate based on engine speed and load;
and determining an original minimum EGR rate as the minimum EGR rate according to the atmospheric pressure, the water temperature, the engine combustion times, the atmospheric temperature, the real-time water temperature of the engine, the starting water temperature of the engine, the air inlet temperature of the engine, the mass flow of fuel steam entering the cylinder from the carbon tank, the engine rotating speed and the basic minimum EGR rate.
2. The method of claim 1, wherein the step of determining the original minimum EGR rate as the minimum EGR rate based on the atmospheric pressure, the water temperature, the number of engine combustion, the atmospheric temperature, the real-time engine water temperature, the engine start water temperature, the engine intake air temperature, the mass and flow of fuel vapor from the canister into the cylinder, the engine speed, and the basic minimum EGR rate comprises:
determining a first multiplication factor r according to the atmospheric pressure and the water temperature 1 ；
Determining a second multiplication factor r according to the combustion times of the engine and the atmospheric temperature 2 ；
Determining a third multiplication factor r according to the real-time water temperature of the engine and the starting water temperature of the engine 3 ；
Determining a fourth multiplication factor r according to the real-time water temperature and the air inlet temperature of the engine 4 ；
Determining a fifth multiplication factor r according to the mass and the flow of fuel steam entering the cylinder from the carbon tank and the rotating speed of the engine 5 。
3. The method of claim 2, wherein the original minimum EGR rate r is EGRVehicleMin Obtained according to the following formula:
r EGRVehicleMin ＝r EGRBenchMin ·(1+r 1 )·(1+r 2 )·(1+r 3 )·(1+r 4 )·(1+r 5 )；
wherein r is EGRBenchMin Representing the base minimum EGR rate.
4. The method of claim 1, further comprising self-learning updating when engine operating conditions are stable:
after the updating stage of self-learning updating is determined, the intake air density target average rho of the fresh air entering the cylinder under the current working condition is determined DsrdAvg Average value rho of intake density filtered value of fresh air actually entering cylinder ActFilterAvg Target air-fuel ratio r DsrdAFRavg And the average value r of the filtered values of the actual air-fuel ratios AFRFilterAvg Updating the initial value of the learning value;
determining a new minimum EGR rate learning value according to the learning value initial value and the last minimum EGR rate learning value under the same working condition;
and determining a final minimum EGR rate according to the current original minimum EGR rate and the new minimum EGR rate learning value.
5. The method for designing the minimum EGR rate according to claim 4, wherein the determination is made to enter a self-learning update phase and then a target average value rho of intake density of fresh air entering the cylinder according to the current operating condition DsrdAvg Average value rho of intake density filtered value of fresh air actually entering cylinder ActFilterAvg Target air-fuel ratio r DsrdAFRavg And the average value r of the actual air-fuel ratio filtered value AFRFilterAvg The step of updating the initial value of the learned value includes:
according to the target average value rho of the intake density of the fresh air entering the cylinder under the current working condition DsrdAvg And the average value rho of the intake density filtered value of the fresh air actually entering the cylinder ActFilterAvg Determining a first judgment value;
according to the target air-fuel ratio r DsrdAFRavg And the average value r of the filtered values of the actual air-fuel ratios AFRFilterAvg Determining a second judgment value;
and determining the initial value of the learning value according to the first judgment value and the second judgment value.
6. The method of designing a minimum EGR rate according to claim 5, characterized in that the first determination value C 1 Obtained according to the following formula:
the second judgment value C 2 Is determined according to the following formula:
7. the method of claim 4, further comprising the steps of, prior to entering the self-learning update phase:
determining, based on the engine and the EGR system, that an activation condition is satisfied;
and entering a stabilization stage after the activation condition is met, and entering an updating stage when the stabilization stage meets a duration condition and the self-learning times are not updated.
8. A minimum EGR rate designing apparatus, comprising:
a first module to determine a base minimum EGR rate based on engine speed and load;
and the second module is used for determining an original minimum EGR rate according to the atmospheric pressure, the water temperature, the engine combustion times, the atmospheric temperature, the real-time engine water temperature, the engine starting water temperature, the engine air inlet temperature, the mass flow of fuel steam entering the cylinder from the carbon tank, the engine rotating speed and the basic minimum EGR rate and taking the original minimum EGR rate as the minimum EGR rate.
9. An electronic device comprising a processor and a memory, the processor and the memory being interconnected;
the memory is used for storing a computer program;
the processor is configured to execute the design method for minimum EGR rate according to any one of claims 1 to 7 when the computer program is invoked.
10. A computer-readable storage medium, characterized in that the computer-readable storage medium stores a computer program which is executed by a processor to implement the design method of minimum EGR rate according to any one of claims 1 to 7.
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