EGR flow correction method and control system

Abstract

This application provides an EGR flow correction method and control system. The EGR flow correction method includes: selecting at least one point between the GPF and the engine cylinder as a measurement point along the exhaust gas delivery path, and obtaining the current exhaust gas flow rate at the measurement point; obtaining a correction weight coefficient between the measurement point and the engine cylinder; determining the current exhaust gas flow rate of the engine cylinder based on the current exhaust gas flow rate at the measurement point and the correction weight coefficient; and adjusting the engine control parameters based on the current exhaust gas flow rate of the engine cylinder. The EGR flow correction method and control system of this application can improve the output performance of the engine.

Description

Technical Field

[0001] This application relates to the field of engine intake and exhaust control system technology, and in particular to an EGR flow correction method and control system. Background Technology

[0002] For related technologies, please refer to the low-pressure EGR system (exhaust gas recirculation system). Figure 1 Exhaust gas is obtained from GPF1 (Gas Particulate Filter), flows through EGR valve 2, and meets fresh air in front of compressor 3 to form a mixture. Then it enters the engine cylinder 5 through compressor 3 and throttle valve 4. The pipeline through which it flows is very long, which can easily cause flow stagnation and affect the engine's output performance. Summary of the Invention

[0003] In view of this, the embodiments of this application aim to provide an EGR flow correction method and control system that can improve the output performance of an engine.

[0004] To achieve the above objectives, embodiments of this application provide an EGR traffic correction method, comprising:

[0005] Along the exhaust gas delivery path, at least one point between the GPF and the engine cylinder is selected as a measurement point to obtain the current exhaust gas flow rate at the measurement point;

[0006] Obtain the correction weighting coefficient between the measurement point and the engine cylinder;

[0007] The current exhaust gas flow rate of the engine cylinder is determined based on the current exhaust gas flow rate at the measurement point and the correction weighting coefficient.

[0008] The engine control parameters are adjusted based on the current exhaust gas flow rate of the engine cylinder.

[0009] In some implementations, the step of selecting at least one point between the GPF and the engine cylinder along the exhaust gas delivery path as a measurement point and obtaining the current exhaust gas flow rate at the measurement point includes:

[0010] The compressor, throttle body, and intake manifold were selected as measurement points.

[0011] The current exhaust gas flow rate of the compressor, the current exhaust gas flow rate of the throttle valve, and the current exhaust gas flow rate of the intake manifold are obtained.

[0012] In some implementations, the current exhaust gas flow rate of the compressor is calculated based on a throttling equation;

[0013] The throttling equation is: the current exhaust gas flow rate of the compressor M1 = C d *A1*P us1 / sqrt(RT1)*f(P us1 / P ds1 ), where C d Where A1 is the flow coefficient, P is the flow area of ​​the EGR valve, and A1 is the flow coefficient. us1 P is the pressure upstream of the EGR valve. ds1 The pressure downstream of the EGR valve is given by R, the gas constant is given by T1, and the temperature of the EGR valve is given by f(P). us1 / P ds1 ) is the pressure ratio function.

[0014] In some implementations, the step of obtaining the current exhaust gas flow rate of the throttle valve includes:

[0015] A first sampling point is established upstream of the throttle valve along the air delivery path to obtain the air flow rate at the first sampling point.

[0016] Determine the duration of airflow from the first sampling point into the throttle valve;

[0017] Based on the flow duration between the first sampling point and the throttle valve, the airflow at the first sampling point before the flow duration is obtained, and used as the current airflow of the throttle valve;

[0018] Obtain the current air-fuel mixture flow rate of the throttle valve;

[0019] The current exhaust gas flow rate of the throttle is determined based on the current air-fuel mixture flow rate and the current air flow rate of the throttle.

[0020] In some implementations, the current air-fuel mixture flow rate of the throttle valve is calculated based on a throttling equation;

[0021] The throttling equation is: Current air-fuel mixture flow rate at the throttle valve M2 = C d *A2*P us2 / sqrt(RT2)*f(P us2 / P ds2 ), where C d Where A is the flow coefficient, A2 is the flow area of ​​the throttle valve, and P is the flow coefficient. us2 P is the pressure upstream of the throttle body. ds2 Here, P represents the pressure downstream of the throttle body, R is the gas constant, T2 is the temperature of the throttle body, and f(P) is the pressure downstream of the throttle body. us2 / P ds2 ) is the pressure ratio function.

[0022] In some implementations, the step of obtaining the current exhaust gas flow rate of the intake manifold includes:

[0023] A second sampling point is established upstream of the intake manifold along the air delivery path to obtain the air flow rate at the second sampling point.

[0024] Determine the flow time of the airflow from the second sampling point to the intake manifold;

[0025] Based on the flow time from the second sampling point to the intake manifold, the air flow rate at the second sampling point before the flow time is obtained, and used as the current air flow rate of the intake manifold;

[0026] Obtain the current air-fuel mixture flow rate of the intake manifold;

[0027] The current exhaust gas flow rate of the intake manifold is determined based on the current air-fuel mixture flow rate and the current air flow rate of the intake manifold.

[0028] In some implementations, the current mixed airflow volume of the intake manifold is obtained in the following way:

[0029] The current air-fuel mixture flow rate in the intake manifold is M3 = P*V / (R*T)*ρ 燃烧油 *(N 冲程 / 2)*(V 转速 / 60), where P is the pressure of the air-fuel mixture in the intake manifold; V is the volume of the intake manifold; T is the absolute temperature of the air-fuel mixture; R is the gas constant; ρ 燃烧油 N is the density of the fuel oil. 冲程 For stroke; V 转速 This is the current engine speed.

[0030] In some implementations, the step of obtaining the correction weighting coefficient between the measurement point and the engine cylinder includes:

[0031] Obtain the airflow path length between the EGR valve and the throttle valve, and the airflow path length between the throttle valve and the engine cylinder;

[0032] Based on the airflow path length between the EGR valve and the throttle valve, determine the correction weighting coefficient between the EGR valve and the throttle valve;

[0033] The correction weighting coefficient between the throttle valve and the engine cylinder is determined based on the airflow path length between the throttle valve and the engine cylinder.

[0034] In some implementations, the correction weighting coefficient between the EGR valve and the throttle valve is determined based on the airflow path length between the EGR valve and the throttle valve as follows: the correction weighting coefficient between the EGR valve and the throttle valve is k1 = L1 / (L1 + L2); where L1 is the airflow path length between the EGR valve and the throttle valve; and L2 is the airflow path length between the throttle valve and the engine cylinder.

[0035] In some implementations, the correction weighting coefficient between the throttle valve and the engine cylinder is determined based on the airflow path length between the throttle valve and the engine cylinder: the correction weighting coefficient between the throttle valve and the engine cylinder k2 = L2 / (L1+L2), where L1 is the airflow path length between the EGR valve and the throttle valve; and L2 is the airflow path length between the throttle valve and the engine cylinder.

[0036] In some implementation schemes, the step of determining the current exhaust gas flow rate of the engine cylinder based on the current exhaust gas flow rate at the measurement point and a correction weighting coefficient includes:

[0037] The current exhaust gas flow rate of the engine cylinder is M4 = M1 + k1 * ΔM (2-1) +k2*△M (3-2) Where M1 is the current exhaust gas flow rate of the EGR valve; M2 is the current exhaust gas flow rate of the throttle valve; M3 is the current exhaust gas flow rate of the intake manifold; k1 is the correction weighting coefficient between the EGR valve and the throttle valve; and k2 is the correction weighting coefficient between the throttle valve and the engine cylinder.

[0038] In some implementations, the engine control parameters include ignition angle and VVT.

[0039] This application embodiment also provides an EGR flow control system, the EGR flow control system comprising:

[0040] The first acquisition module is used to select at least one point between the GPF and the engine cylinder as a measurement point along the gas delivery path, and acquire the current exhaust gas flow rate at the measurement point.

[0041] The second acquisition module is used to acquire the correction weighting coefficient between the measurement point and the engine cylinder;

[0042] The determination module is used to determine the current exhaust gas flow rate of the engine cylinder based on the current exhaust gas flow rate of the measurement point and the correction weighting coefficient.

[0043] The adjustment module is used to adjust the engine control parameters according to the current exhaust gas flow rate of the engine cylinder.

[0044] The EGR flow correction method and control system of this application selects a measurement point in the exhaust gas delivery path, obtains the current exhaust gas flow rate at the measurement point, determines the current exhaust gas flow rate of the engine cylinder based on the current exhaust gas flow rate at the measurement point and a correction weight coefficient, and adjusts the engine control parameters accordingly. This ensures that the engine control parameters match the actual exhaust gas flow rate entering the engine, thereby improving the engine's output performance. Attached Figure Description

[0045] Figure 1 This is a schematic diagram of an engine intake and exhaust system according to an embodiment of related technology;

[0046] Figure 2 This is a flowchart illustrating an embodiment of the EGR traffic correction method of this application.

[0047] Explanation of reference numerals in the attached figures

[0048] GPF1; EGR valve 2; compressor 3; throttle body 4; engine cylinder 5; turbine 6; EGR cooler 7; flow meter 8; mixing valve 9; air filter 10. Detailed Implementation

[0049] The embodiments of this application will be described in further detail below with reference to the accompanying drawings and examples. The following examples are used to illustrate this application, but should not be used to limit the scope of this application.

[0050] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0051] Please refer to Figure 1 In related technologies, exhaust gas is taken from after the GPF (Gas Particulate Filter), flows through the EGR cooler 7 and EGR valve 2, and meets with fresh air before the compressor 3. Then it enters the engine cylinder 5 through the throttle valve 4. The flow path is very long, which can easily cause flow lag. Since the engine control parameters such as ignition angle and VVT are adjusted according to the operating conditions, when the operating conditions change, the engine control parameters change accordingly. However, the air-fuel mixture entering the engine cylinder 5 does not change instantaneously due to the long path, resulting in a mismatch between the engine intake and control parameters, which ultimately affects the engine's output performance.

[0052] Please refer to the following for details. Figure 2 This application provides an EGR traffic correction method, including:

[0053] S10. Along the exhaust gas transport path, select at least one point between the GPF and the engine cylinder as a measurement point, and obtain the current exhaust gas flow rate at the measurement point.

[0054] S20. Obtain the correction weighting coefficient between the measurement point and the engine cylinder.

[0055] S30. Determine the current exhaust gas flow rate of the engine cylinder based on the current exhaust gas flow rate at the measurement point and the correction weighting coefficient. In other words, the exhaust gas flow rate at the measurement point is corrected according to the correction weighting coefficient to obtain the current exhaust gas flow rate entering the engine cylinder.

[0056] S40. Adjust the engine control parameters according to the current exhaust gas flow rate of the engine cylinder.

[0057] In step S10 above, the exhaust gas delivery path is the path through which exhaust gas flows out of the engine cylinder and back to the engine cylinder. In some embodiments, the exhaust gas flows sequentially through the GPF, EGR valve, compressor, throttle valve, and intake manifold before flowing into the engine cylinder. The measurement point is located on at least one of the EGR valve, compressor, throttle valve, and intake manifold, or at least partially between any two of the GPF, EGR valve, compressor, throttle valve, intake manifold, and engine cylinder.

[0058] Understandably, the number of measurement points can be one or more, such as two or more.

[0059] In some embodiments, the engine control parameters include ignition angle and VVT, which are adjusted based on the current exhaust gas flow rate entering the engine cylinders. VVT, or Variable Valve Timing, can adjust the overlap time and timing (part or all) of the engine's intake and exhaust systems, reducing fuel consumption and improving efficiency.

[0060] The EGR flow correction method in this application selects a measurement point along the exhaust gas delivery path, obtains the current exhaust gas flow rate at that point, determines the current exhaust gas flow rate of the engine cylinder based on the current exhaust gas flow rate at the measurement point and a correction weight coefficient, and adjusts the engine control parameters accordingly. This ensures that the engine control parameters match the actual exhaust gas flow rate entering the engine, thereby improving the engine's output performance.

[0061] It is understood that the EGR system in the above embodiments can be a low-pressure or high-pressure EGR system. In some embodiments, the exhaust gas intake is located downstream of the turbine 6, that is, the EGR system is a low-pressure EGR system, which can be applied to more operating conditions compared to a high-pressure EGR system.

[0062] It is understood that the above embodiments are applicable to fuel vehicles or hybrid vehicles.

[0063] For example, step S10, which involves selecting at least one point between the GPF and the engine cylinder along the exhaust gas delivery path as a measurement point and obtaining the current exhaust gas flow rate at that measurement point, includes:

[0064] S11. Select the compressor, throttle body, and intake manifold as measurement points. That is, select three measurement points, located at the compressor, throttle body, and intake manifold respectively.

[0065] S12. Obtain the current exhaust gas flow rate of the compressor, the current exhaust gas flow rate of the throttle valve, and the current exhaust gas flow rate of the intake manifold.

[0066] For example, in step S12, the current exhaust gas flow rate of the compressor is calculated based on the throttling equation;

[0067] The throttling equation is: Current exhaust gas flow rate of the compressor = C d *A1*P us1 / sqrt(RT1)*f(P us1 / P ds1 ), where C d Where A1 is the flow coefficient, P is the flow area of ​​the EGR valve, and A1 is the flow coefficient. us1 P ds1 The pressures upstream and downstream of the EGR valve are respectively, R is the gas constant, T1 is the temperature of the EGR valve, and f(P) is the gas constant. us1 / P ds1 ) is the pressure ratio function.

[0068] It should be noted that the compressor and EGR valve are located close to each other, so the current exhaust gas flow rate can be directly obtained from the EGR valve as the current exhaust gas flow rate of the compressor.

[0069] It is understandable that a differential pressure sensor and a temperature sensor are installed at the EGR valve.

[0070] For example, in step S12, the step of obtaining the current exhaust gas flow rate of the throttle valve includes:

[0071] S121a. A first sampling point is established upstream of the throttle valve along the air delivery path to obtain the airflow at the first sampling point. That is, the airflow will flow through the first sampling point and the throttle valve in sequence.

[0072] S121b Determine the flow time of the airflow from the first sampling point into the throttle valve.

[0073] It is understandable that, since the process of airflow flowing from the first sampling point into the throttle valve takes time, the actual time it takes for the airflow to flow from the first sampling point to the throttle valve during the test can be measured and recorded to form a map table. The flow time of the airflow from the first sampling point into the throttle valve can be determined by looking up the table.

[0074] S121c: Based on the flow time from the first sampling point to the throttle body, obtain the airflow at the first sampling point before that flow time, and use it as the current airflow at the throttle body. In other words, the current airflow at the throttle body is obtained at the first sampling point before the aforementioned flow time.

[0075] S121d: Obtain the current air-fuel mixture flow rate at the throttle valve.

[0076] S121e: Determine the current exhaust gas flow rate of the throttle valve based on the current air-fuel mixture flow rate and the current air flow rate of the throttle valve. Specifically, the current exhaust gas flow rate of the throttle valve is obtained by subtracting the current air flow rate of the throttle valve from the current air-fuel mixture flow rate.

[0077] In some embodiments, to facilitate direct acquisition of air flow rate via flow meter 8, the first sampling point is set in the air delivery path before the air and exhaust gas are mixed. For example, Figure 2 In this process, the flow meter 8 is placed before the mixing valve 9, and the air is mixed with the exhaust gas through the flow meter 8 and the mixing valve 9.

[0078] It is understandable that an air filter 10 is installed upstream of the air delivery path to filter the air, for example in... Figure 2 In the middle, the air filter 10 is located upstream of the flow meter 8.

[0079] For example, in step S121d, the current air-fuel mixture flow rate of the throttle valve is calculated according to the throttle equation;

[0080] The throttling equation is: M2 = C d *A2*P us2 / sqrt(RT2)*f(P us2 / P ds2 ), where C d Where A is the flow coefficient, A2 is the flow area of ​​the throttle valve, and P is the flow coefficient. us2 P ds2 The pressures upstream and downstream of the throttle body are respectively, R is the gas constant, T2 is the throttle body temperature, and f(P) is the pressure upstream and downstream of the throttle body. us2 / P ds2 ) is the pressure ratio function.

[0081] It should be noted that the order in which the current exhaust gas flow rate of the intake manifold is obtained and the current exhaust gas flow rate of the throttle valve are obtained is not limited.

[0082] For example, in step S12, the step of obtaining the current exhaust gas flow rate of the intake manifold includes:

[0083] S122a. Along the air delivery path, establish a second sampling point upstream of the intake manifold and obtain the air flow rate of the second sampling point.

[0084] S122b, Determine the flow time of the airflow from the second sampling point to the intake manifold.

[0085] S122c. Based on the flow duration from the second sampling point to the intake manifold, obtain the air flow rate of the second sampling point before the flow duration, and use it as the current air flow rate of the intake manifold.

[0086] S122d: Obtain the current air-fuel mixture flow rate of the intake manifold.

[0087] S122e. Determine the current exhaust gas flow rate of the intake manifold based on the current mixed gas flow rate and the current air flow rate of the intake manifold.

[0088] It is understandable that the second sampling point and the first sampling point are located at different positions on the air delivery path. In some embodiments, to simplify the process, the second sampling point is the same as the first sampling point, and both are located at the same position on the air delivery path. That is, in establishing the second sampling point upstream of the intake manifold in step S122a, the first sampling point can be directly used as the second sampling point.

[0089] For example, in step S122d, the current mixed airflow rate of the intake manifold is obtained as follows: the current mixed airflow rate of the intake manifold M3 = P*V / (R*T)*ρ 燃烧油 *(N 冲程 / 2)*(V 转速 / 60), where P is the pressure of the air-fuel mixture in the intake manifold; V is the volume of the intake manifold; T is the absolute temperature of the air-fuel mixture; R is the gas constant; ρ 燃烧油 N is the density of the fuel oil. 冲程 For stroke; V 转速 This is the current engine speed.

[0090] For example, step S20 includes:

[0091] S21. Obtain the airflow path length between the EGR valve and the throttle valve, and the airflow path length between the throttle valve and the engine cylinder.

[0092] S22. Determine the correction weighting coefficient between the EGR valve and the throttle valve based on the airflow path length between the EGR valve and the throttle valve.

[0093] S23. Determine the correction weighting coefficient between the throttle valve and the engine cylinder based on the airflow path length between the throttle valve and the engine cylinder.

[0094] In some embodiments, in step S22, the correction weighting coefficient between the EGR valve and the throttle body is k1 = L1 / (L1 + L2); where L1 is the airflow path length between the EGR valve and the throttle body; and L2 is the airflow path length between the throttle body and the engine cylinder.

[0095] In some embodiments, in step S23, the correction weighting coefficient between the throttle valve and the engine cylinder is k2 = L2 / (L1+L2), where L1 is the airflow path length between the EGR valve and the throttle valve; and L2 is the airflow path length between the throttle valve and the engine cylinder.

[0096] For example, step S30 includes:

[0097] The current exhaust gas flow rate of the engine cylinder is M4 = M1 + k1 * ΔM (2-1) +k2*△M (3-2) Where M1 is the current exhaust gas flow rate of the EGR valve; M2 is the current exhaust gas flow rate of the throttle valve; M3 is the current exhaust gas flow rate of the intake manifold; k1 is the correction weighting coefficient between the EGR valve and the throttle valve; and k2 is the correction weighting coefficient between the throttle valve and the engine cylinder.

[0098] In some embodiments, the EGR flow correction method includes:

[0099] S11. Select the compressor, throttle body, and intake manifold as measurement points. That is, select three measurement points, located at the compressor, throttle body, and intake manifold respectively.

[0100] S12. Obtain the current exhaust gas flow rate of the compressor, the current exhaust gas flow rate of the throttle valve, and the current exhaust gas flow rate of the intake manifold.

[0101] The current exhaust gas flow rate of the compressor is calculated based on the throttling equation; the throttling equation is: Current exhaust gas flow rate of the compressor = C d *A1*P us1 / sqrt(RT1)*f(P us1 / P ds1 ), where C d Where A1 is the flow coefficient, P is the flow area of ​​the EGR valve, and A1 is the flow coefficient. us1 P ds1 The pressures upstream and downstream of the EGR valve are respectively, R is the gas constant, T1 is the temperature of the EGR valve, and f(P) is the gas constant. us1 / P ds1) is the pressure ratio function.

[0102] The steps for obtaining the current exhaust gas flow rate of the throttle valve are as follows: S121a. Establish a first sampling point upstream of the throttle valve along the air transport path and obtain the air flow rate at the first sampling point. That is, the airflow will flow sequentially through the first sampling point and the throttle valve. S121b. Determine the flow time of the airflow from the first sampling point into the throttle valve. S121c. Based on the flow time from the first sampling point to the throttle valve, obtain the air flow rate at the first sampling point before that flow time, as the current air flow rate of the throttle valve. S121d. Obtain the current air-fuel mixture flow rate of the throttle valve. The current air-fuel mixture flow rate of the throttle valve is calculated according to the throttle equation; the throttle equation is: M2 = C d *A2*P us2 / sqrt(RT2)*f(P us2 / P ds2 ), where C d Where A is the flow coefficient, A2 is the flow area of ​​the throttle valve, and P is the flow coefficient. us2 P ds2 The pressures upstream and downstream of the throttle body are respectively, R is the gas constant, T2 is the throttle body temperature, and f(P) is the pressure upstream and downstream of the throttle body. us2 / P ds2 S121e is the pressure ratio function. Based on the current air-fuel mixture flow rate and the current air flow rate of the throttle valve, determine the current exhaust gas flow rate of the throttle valve.

[0103] The step of obtaining the current exhaust gas flow rate of the intake manifold is as follows: S122a, establish a second sampling point upstream of the intake manifold along the air transport path, and obtain the air flow rate at the second sampling point. S122b, determine the flow duration of the airflow from the second sampling point to the intake manifold. S122c, based on the flow duration from the second sampling point to the intake manifold, obtain the air flow rate at the second sampling point before that flow duration, and use it as the current air flow rate of the intake manifold. S122d, obtain the current mixed air flow rate of the intake manifold. The current mixed air flow rate of the intake manifold is obtained as follows: Current mixed air flow rate of the intake manifold M3 = P*V / (R*T)*ρ 燃烧油 *(N 冲程 / 2)*(V 转速 / 60), where P is the pressure of the air-fuel mixture in the intake manifold; V is the volume of the intake manifold; T is the absolute temperature of the air-fuel mixture; R is the gas constant; ρ 燃烧油 N is the density of the fuel oil. 冲程 For stroke; V 转速 The current engine speed is given. S122e: Determine the current exhaust gas flow rate of the intake manifold based on the current air-fuel mixture flow rate and the current air flow rate of the intake manifold.

[0104] S21. Obtain the airflow path length between the EGR valve and the throttle valve, and the airflow path length between the throttle valve and the engine cylinder.

[0105] S22. Determine the correction weighting coefficient between the EGR valve and the throttle valve based on the airflow path length between the EGR valve and the throttle valve. The correction weighting coefficient between the EGR valve and the throttle valve is k1 = L1 / (L1 + L2); where L1 is the airflow path length between the EGR valve and the throttle valve; and L2 is the airflow path length between the throttle valve and the engine cylinder.

[0106] S23. Determine the correction weighting coefficient between the throttle valve and the engine cylinder based on the airflow path length between the throttle valve and the engine cylinder. Wherein, the correction weighting coefficient k2 between the throttle valve and the engine cylinder is L2 / (L1+L2), where L1 is the airflow path length between the EGR valve and the throttle valve; and L2 is the airflow path length between the throttle valve and the engine cylinder.

[0107] S30. Determine the current exhaust gas flow rate of the engine cylinder based on the current exhaust gas flow rate at the measurement point and the correction weighting coefficient. The current exhaust gas flow rate of the engine cylinder is M4 = M1 + k1 * ΔM (2-1) +k2*△M (3-2) Where M1 is the current exhaust gas flow rate of the EGR valve; M2 is the current exhaust gas flow rate of the throttle valve; M3 is the current exhaust gas flow rate of the intake manifold; k1 is the correction weighting coefficient between the EGR valve and the throttle valve; and k2 is the correction weighting coefficient between the throttle valve and the engine cylinder.

[0108] S40. Adjust the engine control parameters according to the current exhaust gas flow rate of the engine cylinder.

[0109] This application embodiment also provides an EGR flow control system, the EGR flow control system comprising:

[0110] The first acquisition module is used to select at least one point between the GPF and the engine cylinder as a measurement point along the gas delivery path, and acquire the current exhaust gas flow rate at the measurement point.

[0111] The second acquisition module is used to acquire the correction weighting coefficient between the measurement point and the engine cylinder.

[0112] The determination module is used to determine the current exhaust gas flow rate of the engine cylinder based on the current exhaust gas flow rate of the measurement point and the correction weighting coefficient.

[0113] The adjustment module is used to adjust the engine control parameters according to the current exhaust gas flow rate of the engine cylinder.

[0114] In the description of this application, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the embodiments of this application. In this application, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Furthermore, without contradiction, those skilled in the art can combine different embodiments or examples described in this application, as well as features of different embodiments or examples.

[0115] The above description is merely a preferred embodiment of this application and is not intended to limit the application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. An EGR flow correction method, characterized in that, include: Along the exhaust gas delivery path, the compressor, throttle valve, and intake manifold are selected as measurement points to obtain the current exhaust gas flow rate of the compressor, the throttle valve, and the intake manifold. The exhaust gas flows through the compressor, the throttle valve, and the intake manifold in sequence before flowing into the engine cylinder. The current exhaust gas flow rate at the EGR valve is obtained as the current exhaust gas flow rate of the compressor. Obtain the correction weighting coefficient k1 between the EGR valve and the throttle body, and the correction weighting coefficient k2 between the throttle body and the engine cylinder, wherein: k1 = L1 / (L1 + L2), where L1 is the airflow path length between the EGR valve and the throttle body; L2 is the airflow path length between the throttle body and the engine cylinder. k2 = L2 / (L1 + L2), where L1 is the airflow path length between the EGR valve and the throttle body; L2 is the airflow path length between the throttle body and the engine cylinder. According to the formula M4=M1+k1*△M （2-1） +k2*△M （3-2） Determine the current exhaust gas flow rate M4 of the engine cylinder, where M1 is the current exhaust gas flow rate of the compressor, M2 is the current exhaust gas flow rate of the throttle valve, and M3 is the current exhaust gas flow rate of the intake manifold. Adjust the engine control parameters according to the current exhaust gas flow rate M4 of the engine cylinder.

2. The EGR flow correction method as described in claim 1, characterized in that, The current exhaust gas flow rate of the compressor is calculated based on the throttling equation; The throttling equation is: the current exhaust gas flow rate of the compressor M1 = C d *A1*P us1 / sqrt(RT1)*f(P) us1 / P ds1 ), where C d Where A1 is the flow coefficient, P is the flow area of ​​the EGR valve, and A1 is the flow coefficient. us1 P ds1 The pressures upstream and downstream of the EGR valve are respectively, R is the gas constant, T1 is the temperature of the EGR valve, and f(P) is the gas constant. us1 / P ds1 ) is the pressure ratio function.

3. The EGR flow correction method as described in claim 1, characterized in that, The step of obtaining the current exhaust gas flow rate of the throttle valve includes: A first sampling point is established upstream of the throttle valve along the air delivery path to obtain the air flow rate at the first sampling point. Determine the duration of airflow from the first sampling point into the throttle valve; Based on the flow duration between the first sampling point and the throttle valve, the airflow at the first sampling point before the flow duration is obtained, and used as the current airflow of the throttle valve; Obtain the current air-fuel mixture flow rate of the throttle valve; The current exhaust gas flow rate of the throttle is determined based on the current air-fuel mixture flow rate and the current air flow rate of the throttle.

4. The EGR flow correction method as described in claim 3, characterized in that, The current air-fuel mixture flow rate of the throttle valve is calculated based on the throttle equation; The throttling equation is: Current air-fuel mixture flow rate at the throttle valve M2 = C d *A2*P us2 / sqrt(RT2)*f(P) us2 / P ds2 ), where C d Where A is the flow coefficient, A2 is the flow area of ​​the throttle valve, and P is the flow coefficient. us2 P ds2 The pressures upstream and downstream of the throttle body are respectively, R is the gas constant, T2 is the throttle body temperature, and f(P) is the pressure upstream and downstream of the throttle body. us2 / P ds2 ) is the pressure ratio function.

5. The EGR flow correction method as described in claim 1, characterized in that, The step of obtaining the current exhaust gas flow rate of the intake manifold includes: A second sampling point is established upstream of the intake manifold along the air delivery path to obtain the air flow rate at the second sampling point. Determine the flow time of the airflow from the second sampling point to the intake manifold; Based on the flow time from the second sampling point to the intake manifold, the air flow rate at the second sampling point before the flow time is obtained, and used as the current air flow rate of the intake manifold; Obtain the current air-fuel mixture flow rate of the intake manifold; The current exhaust gas flow rate of the intake manifold is determined based on the current air-fuel mixture flow rate and the current air flow rate of the intake manifold.

6. The EGR flow correction method as described in claim 5, characterized in that, The method for obtaining the current mixed airflow volume of the intake manifold is as follows: The current air-fuel mixture flow rate M3 in the intake manifold is calculated as follows: M3 = P * V / (R * T) * ρ 燃烧油 *(N 冲程 / 2)*(V 转速 / 60), where P is the pressure of the air-fuel mixture in the intake manifold; V is the volume of the intake manifold; T is the absolute temperature of the air-fuel mixture; R is the gas constant; ρ 燃烧油 N is the density of the fuel oil. 冲程 For stroke; V 转速 This is the current engine speed.

7. The EGR flow correction method as described in claim 1, characterized in that, The engine control parameters include ignition angle and VVT.

8. An EGR flow control system, which employs the EGR flow correction method according to any one of claims 1 to 7, characterized in that, The EGR flow control system includes: The first acquisition module is used to select the compressor, throttle valve and intake manifold as measurement points along the gas delivery path, and acquire the current exhaust gas flow rate of the compressor, the throttle valve and the intake manifold, wherein the exhaust gas flows into the engine cylinder after passing through the compressor, the throttle valve and the intake manifold in sequence, and the current exhaust gas flow rate at the EGR valve is acquired as the current exhaust gas flow rate of the compressor. The second acquisition module is used to acquire the correction weighting coefficient between the measurement point and the engine cylinder; The determination module is used to determine the current exhaust gas flow rate of the engine cylinder based on the current exhaust gas flow rate of the measurement point and the correction weighting coefficient. The adjustment module is used to adjust the engine control parameters according to the current exhaust gas flow rate of the engine cylinder.

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