A calibration data screening and collection method for an engine with an EGR system

Abstract

The present invention provides a calibration data screening and collection method for an engine with an EGR system, and relates to the technical field of engine bench calibration data collection. The calibration data screening and collection method for an engine with an EGR system is applied after the dual VVT completes the basic data screening and scanning, and then performs the EGR scanning work of the corresponding dual VVT selection point, and then screens the full MAP working condition to screen out the working condition points with suspected high exhaust gas residual coefficients. The dual VVT refers to the intake and exhaust VVT combination, and includes the following steps: S1. First, formulate the engine working point, formulate several working points; S2. Then, according to the calibration process, collect the dual VVT according to the calibration data collection rules. In the present invention, compared with the exhaustive method of scanning points, the number of scanning points of this method is about one-seventh of the exhaustive method. For some working points, it accounts for more than two-fifths of the full map, with a fuel consumption benefit of 1-2%, and has greater benefits in both calibration cycle and calibration effect.

Description

Technical Field

[0001] The invention relates to the technical field of engine bench calibration data acquisition, in particular to a calibration data screening and acquisition method for an engine with an EGR system. Background Art

[0002] At present, in the process of engine bench calibration, there are many variables that need to be calibrated. The increasingly complex engine system needs to simultaneously control the parameters such as ignition angle, fuel injection density, intake and exhaust VVT and EGR. The combination of various parameters makes the data that needs to be collected increase exponentially.

[0003] Take a certain engine working condition as an example, such as: 2000rpm@100Nm, to complete the VVT ​​combination collection of this working condition (taking the intake VVT ​​activity range of 0-70°CA, the exhaust VVT activity range of 0-50°CA, and an interval of 10°CA as an example), it is necessary to collect at least 7*5=35 parameters (the working condition point when EGR is not turned on needs to collect the whole vehicle working condition for backup, and EGR cannot be turned on directly for calibration);

[0004] After adding the information collection of different EGR opening combinations (with 5% opening as an interval), 35*10=350 combined operating points need to be collected. The above processes all need to ensure torque stability, ignition angle and excess air coefficient stability. The more variables, the worse the system stability and the longer the actual operation time of the bench. Taking the nearly 200 operating points of the full MAP of a general naturally aspirated engine as an example, the entire data collection workload will be very large. In addition to basic data collection, the calibration system accounts for a larger proportion of the collection of inflation and torque models. Therefore, it is not advisable and impossible to collect relevant data in all combinations.

[0005] In the actual bench calibration process, each company generally presets the best fuel consumption VVT combination point, which is the global fuel consumption optimum point, and uses this as the preset to derive the calibration process. Taking the above-mentioned working condition as an example, the intake and exhaust VVT combination is collected first, and then the EGR data is collected. Then the collection working condition changes to 7*5+10=45 combination working condition points. Compared with the exhaustive method, it has indeed greatly improved the calibration efficiency, and it has also become the mainstream bench data collection method for EGR engines in the industry. However, there is an obvious theoretical deviation in the preset of this method: that is, the best VVT combination point is selected based on the lowest fuel consumption and the best emissions. The VVT ​​combination point with the largest exhaust gas residual coefficient is generally selected, because the larger the exhaust gas residual coefficient, that is, the higher the "internal" EGR rate, the more it will produce

[0006] The fuel saving and emission reduction effects are similar to those of an external EGR system. However, in an external EGR system, especially an external cooled EGR system, the "internal" EGR becomes a resistance item for fuel saving and emission reduction due to the high temperature of the residual exhaust gas. The exhaust gas residual coefficient should be minimized, and sufficient external circulation cooled EGR gas should be introduced at the same time to truly tap the potential of the engine. Therefore, for engines with EGR systems, especially those with cooled EGR systems, the current mainstream engine calibration data collection method may not be able to apply the global optimal operating point, and there are obvious problems. And if the optimal combination is simply found through exhaustive enumeration, it is difficult to implement due to the huge workload.

[0007] Therefore, there is an urgent need to reduce the residual interference of exhaust gas without increasing too much workload, select the global optimal actuator combination point, so as to maximize the potential of the engine and successfully complete the engine calibration work. Therefore, those skilled in the art provide a calibration data screening and collection method for an engine with an EGR system to solve the problems raised in the above background technology. Summary of the invention

[0008] 1. Technical issues to be resolved

[0009] In view of the shortcomings of the prior art, the present invention provides a calibration data screening and collection method for an engine with an EGR system. The method completes the optimal combination collection and screening under the premise of less data collection workload, and solves the problems of the current conventional bench calibration data collection method in mining the optimal working conditions of the engine with EGR, and the exhaustive method with excessive workload and too long calibration time.

[0010] (II) Technical solution

[0011] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0012] A calibration data screening and collection method for an engine with an EGR system, the method is applied after the dual VVT completes the basic data screening and sweeping, then performs the EGR sweeping work of the corresponding dual VVT selection point, and then screens the full MAP working condition to screen out the working condition point with a suspected high exhaust gas residual coefficient, the dual VVT refers to the intake and exhaust VVT combination, and includes the following steps:

[0013] S1. First, the engine operating point is determined, and several operating points are determined. For the determined operating points, the EGR opening and EGR rate that have been swept in the previous stage are used to perform a secondary dual VVT sweep;

[0014] S2. Then, according to the calibration process, the dual VVT is collected according to the calibration data collection rules. When collecting data at the calibration point, a dual VVT operating point with low fuel consumption, low emissions, and more stable combustion is selected;

[0015] S3. After the dual VVT operating point combination is determined, different EGR rates and EGR opening data under the selected dual VVT operating point combination under all operating conditions are collected respectively;

[0016] S4. According to the parameters obtained in steps S1-S3, select some working conditions as the second round of key calibration data collection working conditions, and perform different dual VVT sweeps again based on some key parameters that have been measured before in the working conditions;

[0017] S5. Adjust the EGR parameters of the dual VVT that has been confirmed for the second time for the key working condition to maximize the potential of the working condition. At this point, the calibration data collection of the dual VVT and EGR configuration data is completed.

[0018] Furthermore, after the operation of step S5, the sweep results are analyzed to obtain corresponding data conclusions, and the operating points and their corresponding dual VVTs that can clearly reduce fuel consumption and increase the external EGR rate are screened out, and then a detailed EGR sweep is performed.

[0019] Furthermore, after step S5, after the dual VVT completes the basic data screening and scanning, the EGR scanning work of the corresponding dual VVT selection point is performed, and then the full MAP operating conditions are screened to screen out the operating points suspected to have a higher exhaust gas residual coefficient.

[0020] Furthermore, EGR is the abbreviation of Exhaust Gas Re-circulation, which refers to exhaust gas recirculation. It is a technology commonly used in internal combustion engines to reduce combustion temperature and NOx emissions in the cylinder and improve thermal efficiency. Cooled EGR is to first cool the exhaust gas entering the cylinder and then mix it with the air to enter the cylinder, which has better fuel saving and emission reduction effects.

[0021] Furthermore, the calibration data acquisition refers to the acquisition of matching test data of different controllers on the engine test bench, formulating a set of specific matching control parameters that match the engine so that the engine has good steady-state performance at different speeds and torques, while ensuring the engine's operating reliability, no knocking, and no overheating, to achieve the engine's designed power, torque and fuel consumption performance.

[0022] (III) Beneficial effects

[0023] The present invention provides a calibration data screening and collection method for an engine with an EGR system. It has the following beneficial effects:

[0024] 1. The present invention provides a calibration data screening and collection method for an engine with an EGR system. Compared with the exhaustive point scanning method, the number of points scanned by this method is about one-seventh of that of the exhaustive method. For some operating points, it accounts for more than two-fifths of the entire map, with a 1-2% fuel consumption benefit, and has greater benefits in both calibration cycle and calibration effect.

[0025] 2. The present invention provides a calibration data screening and collection method for an engine with an EGR system. The method is applied after the dual VVT completes the basic data screening and sweeping, and then performs the EGR sweep work of the corresponding dual VVT selection point, and then screens the full MAP operating conditions to screen out the operating points suspected to have a high exhaust gas residual coefficient. For the above-selected operating points, a secondary VVT sweep is performed using the EGR opening and EGR rate that have completed the sweep rate in the early stage, and the sweep results are analyzed to obtain corresponding data conclusions, and the operating points and their corresponding VVT combinations that can clearly reduce fuel consumption and increase the external EGR rate are screened out, and then a detailed EGR sweep is performed, so as to achieve a better collection effect on the calibration data VVT combination and the EGR configuration data. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the engine universal operating point of the present invention;

[0027] Figure 2 It is a schematic diagram of the fuel consumption rate of the dual VVT sweep under a certain working condition of the engine of the present invention;

[0028] Figure 3 It is a broken line graph 1 of various parameters corresponding to different EGR valve openings under a certain working condition of a fixed VVT of the present invention;

[0029] Figure 4 It is a broken line graph 2 of various parameters corresponding to different EGR rates under a certain working condition with fixed VVT of the present invention;

[0030] Figure 5 It is a schematic diagram of the key operating points that need to be retested among the universal operating points of the engine of the present invention;

[0031] Figure 6 This is a schematic diagram of the VVT ​​combined fuel consumption under the key working conditions screened out by a certain engine of the present invention. DETAILED DESCRIPTION

[0032] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention.

[0033] All other embodiments obtained by persons of ordinary skill in the art based on the embodiments of the present invention without creative work are within the scope of protection of the present invention.

[0034] Example:

[0035] like Figure 1-6As shown, an embodiment of the present invention provides a calibration data screening and collection method for an engine with an EGR system. The method is applied after the dual VVT completes the basic data screening and sweeping, and then performs the EGR sweeping work of the corresponding dual VVT selection point, and then screens the full MAP working condition to screen out the working condition point with a suspected high exhaust gas residual coefficient. The dual VVT refers to the intake and exhaust VVT combination, and includes the following steps:

[0036] S1. First, the engine operating point is determined, and several operating points are determined. For the selected operating points, the EGR opening and EGR rate that have been swept in the previous stage are used to perform a secondary dual VVT sweep;

[0037] S2. Then, according to the calibration process, the dual VVT is collected according to the calibration data collection rules. When collecting data at the calibration point, a dual VVT operating point with low fuel consumption, low emissions, and more stable combustion is selected;

[0038] S3. After the dual VVT operating point combination is determined, different EGR rates and EGR opening data under the selected dual VVT operating point combination under all operating conditions are collected respectively;

[0039] S4. According to the parameters obtained in steps S1-S3, select some working conditions as the second round of key calibration data collection working conditions, and perform different dual VVT sweeps again based on some key parameters that have been measured before in the working conditions;

[0040] S5. Adjust the EGR parameters of the dual VVT that has been confirmed for the second time for the key working condition to maximize the potential of the working condition. At this point, the collection of the dual VVT and EGR configuration data for the calibration data is completed.

[0041] Then analyze the scanning results, draw corresponding data conclusions, and screen out the operating points and their corresponding dual VVT that can clearly reduce fuel consumption and increase the external EGR rate, and then perform a detailed EGR sweep. After the dual VVT completes the basic data screening and scanning, perform the EGR sweep of the corresponding dual VVT selection point, and then screen the full MAP operating conditions to screen out the operating points suspected to have a high exhaust gas residual coefficient.

[0042] EGR is the abbreviation of Exhaust Gas Re-circulation, which refers to exhaust gas recirculation. It is a technology commonly used by internal combustion engines to reduce combustion temperature and NOx emissions in the cylinder and improve thermal efficiency.

[0043] EGR is to first cool the exhaust gas entering the cylinder and then mix it with the air before entering the cylinder, which has better fuel saving and emission reduction effects;

[0044] Calibration data collection refers to the collection of matching test data of different controllers on the engine test bench, formulating a set of specific matching control parameters that match the engine so that the engine has good steady-state performance at different speeds and torques, and achieving the engine's designed power, torque and fuel consumption performance while ensuring engine reliability, no knocking, and no overheating. Calibration data collection is the basis for formulating controller parameters. As the engine electronic fuel injection system becomes more and more complex, more and more sensors and controllers are needed, and more and more calibration data needs to be collected, and the test bench calibration cycle is extended accordingly;

[0045] The VVT ​​of intake and exhaust VVT is the abbreviation of Variable Valve Timing, which is a technology commonly used in engines. The intake and exhaust VVT can adjust the overlap time and timing (part or all) of the engine intake and exhaust system by changing the corresponding relationship between the engine intake and exhaust camshaft positions and the crankshaft positions, thereby reducing fuel consumption and improving efficiency.

[0046] The exhaust gas residual coefficient refers to the ratio (mass or volume ratio) of the residual exhaust gas in the cylinder at the end of each intake cycle to the actual fresh charge entering the cylinder per cycle.

[0047] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A calibration data screening and collection method for an engine with an EGR system, which is applied after the dual VVT completes the basic data screening and sweeping, and then performs the EGR sweeping work of the corresponding dual VVT selection point, and then screens the full MAP working condition to screen out the working condition point with a suspected high exhaust gas residual coefficient. The dual VVT refers to the intake and exhaust VVT combination, which is characterized in that: The following steps are involved: S1. First, the engine operating point is formulated, and several operating points are formulated. For the formulated operating points, the EGR opening and EGR rate that have been swept in the previous stage are used to perform a secondary dual VVT sweep; S2. Then, according to the calibration process, the dual VVT is collected according to the calibration data collection rules. When collecting data at the calibration point, a dual VVT operating point with low fuel consumption, low emissions, and more stable combustion is selected; S3. After the dual VVT operating point combination is determined, different EGR rates and EGR opening data under the selected dual VVT operating point combination under all operating conditions are collected respectively; S4. According to the parameters obtained in steps S1-S3, select some working conditions as the second round of key calibration data collection working conditions, and perform different dual VVT sweeps again based on some key parameters that have been measured before in the working conditions; S5. Adjust the EGR parameters of the dual VVT that has been confirmed for the second time for the key working condition to maximize the potential of the working condition. At this point, the collection of the dual VVT and EGR configuration data for the calibration data is completed.

2. The calibration data screening and collection method for an engine with an EGR system according to claim 1, characterized in that: After the step S5 is performed, the scanning results are analyzed to obtain corresponding data conclusions, and the operating points and their corresponding dual VVTs that can clearly reduce fuel consumption and increase the external EGR rate are screened out, and then a detailed EGR scan is performed.

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