A control method, device and equipment for EGR system entering closed loop and a medium

Abstract

The application discloses an EGR system entering a closed loop control method, device, equipment and medium, and the method comprises the following steps: judging whether an EGR closed loop enabling condition is met; if yes, entering an EGR closed loop enabling state; if no, entering an EGR closed loop non-enabling state; in the EGR closed loop enabling state, determining a target EGR rate, filtering the target EGR rate to obtain a filtered target EGR rate; determining an actual EGR rate, determining an EGR rate difference according to the actual EGR rate, the target EGR rate and the filtered target EGR rate, and then determining an EGR rate difference change rate according to the EGR rate difference; performing EGR closed loop control by using a PID control algorithm according to the EGR rate difference and the EGR rate difference change rate; wherein, P term and D term control are always in an activated state, and I term control is determined whether to be activated according to an I term additional activation condition. The application improves the EGR closed loop control stability by EGR closed loop enabling control optimization.

Description

Technical Field

[0001] This invention belongs to the field of engine control technology, specifically relating to a control method, device, equipment, and medium for an EGR system to enter a closed loop. Background Technology

[0002] Exhaust gas recirculation (EGR) involves recirculating exhaust gases from the exhaust system and reintroducing them into the intake system. EGR systems offer advantages in improving emissions, reducing fuel consumption, and enhancing anti-knock capabilities. In low-pressure EGR systems, optimizing the control of the mixing valve is particularly effective in improving EGR. Therefore, this paper proposes optimizing the EGR closed-loop enable control to enhance the stability of EGR closed-loop control. Summary of the Invention

[0003] In view of the above-mentioned defects or improvement needs of the prior art, the present invention provides a control method, device, equipment and medium for EGR system to enter the closed loop, thereby solving the stability problem of EGR closed-loop control.

[0004] To achieve the above objectives, according to a first aspect of the present invention, a control method for an EGR system to enter a closed loop is provided, the method comprising:

[0005] Determine if the EGR closed-loop enable condition is met; if yes, enter the EGR closed-loop enable state; if no, enter the EGR closed-loop disabled state.

[0006] Under EGR closed-loop enabled state, the target EGR rate is determined and filtered to obtain the filtered target EGR rate;

[0007] Determine the actual EGR rate, determine the EGR rate difference based on the actual EGR rate, the target EGR rate, and the filtered target EGR rate, and then determine the rate of change of the EGR rate difference based on the EGR rate difference.

[0008] Based on the EGR rate difference and the rate of change of the EGR rate difference, a PID control algorithm is used for EGR closed-loop control; among them, the P-term and D-term controls are always active, while the I-term control is activated based on the additional activation conditions of the I-term.

[0009] In the above scheme, the EGR closed-loop enabling conditions include:

[0010] No faults were found in any of the components of the EGR system;

[0011] No fuel cut-off request was received and the fuel cut-off recovery time exceeded the preset time;

[0012] The minimum EGR rate condition for EGR closed-loop enable is satisfied;

[0013] The engine speed is within the preset speed range;

[0014] Intake air temperature is within the preset range;

[0015] Engine coolant temperature is within the preset range;

[0016] Atmospheric temperature is within the preset range;

[0017] Atmospheric pressure meets the preset threshold.

[0018] The EGR closed-loop enable condition is met when all of the above conditions are met simultaneously; otherwise, the EGR closed-loop enable condition is not met.

[0019] In the above scheme, the condition for enabling the minimum EGR rate in the EGR closed loop is determined as follows:

[0020] When the difference between the target EGR rate and the minimum EGR rate is greater than the preset value A, the condition for enabling the minimum EGR rate in the EGR closed loop is met.

[0021] If the difference between the target EGR rate and the minimum EGR rate is not greater than the preset value B, and the absolute value of the difference between the target EGR rate and the actual EGR rate is not greater than the preset value, then the minimum EGR rate condition for enabling the EGR closed loop is not met; where the preset value A is greater than the preset value B.

[0022] In other cases, the minimum EGR rate condition for EGR closed-loop enable remains in the previous state; when the vehicle is powered on, the minimum EGR rate condition for EGR closed-loop enable is not met by default.

[0023] In the above scheme, the intake air temperature within the preset range includes:

[0024] If the current state is EGR closed-loop disabled, then enter the EGR closed-loop enabled state, ensuring that the intake air temperature is not lower than the first minimum intake air temperature and does not exceed the first maximum intake air temperature; if the current state is EGR closed-loop enabled, then exit the EGR closed-loop enabled state and enter the EGR closed-loop disabled state, ensuring that the intake air temperature is lower than the second minimum intake air temperature or exceeds the second maximum intake air temperature; wherein, the second minimum intake air temperature is less than the first minimum intake air temperature, less than the first maximum intake air temperature, and less than the second maximum intake air temperature.

[0025] Similarly, engine coolant temperature within the preset range includes:

[0026] If the current state is EGR closed-loop disabled, then enter the EGR closed-loop enabled state, ensuring that the engine coolant temperature is not lower than the first minimum coolant temperature and does not exceed the first maximum coolant temperature; if the current state is EGR closed-loop enabled, then exit the EGR closed-loop enabled state and enter the EGR closed-loop disabled state, ensuring that the engine coolant temperature is lower than the second minimum coolant temperature or exceeds the second maximum coolant temperature; wherein, the second minimum coolant temperature is less than the first minimum coolant temperature, less than the first maximum coolant temperature, and less than the second maximum coolant temperature.

[0027] Similarly, atmospheric temperature within the preset range includes:

[0028] If the current state is EGR closed-loop disabled, then enter the EGR closed-loop enabled state, ensuring that the atmospheric temperature is not lower than the first minimum atmospheric temperature and does not exceed the first maximum atmospheric temperature; if the current state is EGR closed-loop enabled, then exit the EGR closed-loop enabled state and enter the EGR closed-loop disabled state, ensuring that the atmospheric temperature is lower than the second minimum atmospheric temperature or exceeds the second maximum atmospheric temperature; wherein, the second minimum atmospheric temperature is less than the first minimum atmospheric temperature, less than the first maximum atmospheric temperature, and less than the second maximum atmospheric temperature.

[0029] In the above scheme, atmospheric pressure meeting the preset threshold includes:

[0030] If the atmospheric pressure exceeds the preset minimum atmospheric pressure for enabling, the system enters the EGR closed-loop enabled state; if the atmospheric pressure is lower than the preset minimum atmospheric pressure for deactivating, the system exits the EGR closed-loop enabled state and enters the EGR closed-loop disabled state; wherein, the preset minimum atmospheric pressure for enabling is greater than the preset minimum atmospheric pressure for deactivating.

[0031] In the above scheme, the target EGR rate is filtered to obtain the filtered target EGR rate, including:

[0032] For each sampling period, determine the filtering time;

[0033] The target EGR rate after filtering in the current sampling period is determined based on the target EGR rate of the current sampling period, the target EGR rate of the previous sampling period, the sampling time interval, the filtering time, and the target EGR rate after filtering in the previous sampling period.

[0034] In the above scheme, determining the filtering time includes:

[0035] Determine the turbocharger response time τ Boost The time τ from the exhaust gas flowing from the EGR valve to the EGR exhaust gas junction. EGR Among them, the turbocharger response time τ Boost The time it takes for the air-fuel mixture to flow from the turbocharger compressor to the throttle outlet;

[0036] Based on the turbocharger response time τ Boost The time τ from the exhaust gas flowing from the EGR valve to the EGR exhaust gas junction. EGR Determine the filter time coefficient for the target EGR rate

[0037] Based on the filter time coefficient k of the target EGR rate T Determine the rate of change dk of the filter time coefficient for the target EGR rate.T :

[0038]

[0039] In the formula, dk T dk is the rate of change of the filter time coefficient for the target EGR rate in the current sampling period. T (z) represents the rate of change of the filter time coefficient of the target EGR rate in the previous sampling period, k T k is the filter time coefficient for the target EGR rate of the current sampling period. T (z) is the filtering time coefficient for the target EGR rate of the previous sampling period, and Δt is the sampling time interval. c It is a time constant;

[0040] The rate of change dk of the filter time coefficient based on the target EGR rate T The filtering time is determined by looking up a table.

[0041] In the above scheme, the turbocharger response time τ Boost The time τ from the exhaust gas flowing from the EGR valve to the EGR exhaust gas junction. EGR All are determined by engine speed n eng and the actual intake air density rho entering the cylinder Act Calibration determined;

[0042] The specific calibration method is as follows: at different engine speeds n eng And different actual intake air densities rho entering the cylinder Act The result is obtained by averaging multiple samples under different EGR rates.

[0043] In the above scheme, the EGR rate difference is determined based on the actual EGR rate, the target EGR rate, and the filtered target EGR rate, including:

[0044] (1) If the target EGR rate is greater than the filtered target EGR rate, then the EGR rate difference is:

[0045] ① When the actual EGR rate is greater than the target EGR rate, the difference in EGR rates is equal to the target EGR rate minus the actual EGR rate;

[0046] ② When the actual EGR rate is less than the target EGR rate after filtering, the EGR rate difference is equal to the target EGR rate after filtering minus the actual EGR rate;

[0047] ③ In other cases, the EGR rate difference is equal to 0;

[0048] The priority of the above three situations decreases in the following order;

[0049] (2) If the target EGR rate is less than the filtered target EGR rate, then the EGR rate difference is:

[0050] ① When the actual EGR rate is less than the target EGR rate, the difference in EGR rates is equal to the target EGR rate minus the actual EGR rate;

[0051] ② When the actual EGR rate is greater than the target EGR rate after filtering, the EGR rate difference is equal to the target EGR rate after filtering minus the actual EGR rate;

[0052] ③ In other cases, the EGR rate difference is equal to 0;

[0053] The priority of the above three situations decreases in the following order;

[0054] (3) In other cases, the EGR rate difference is equal to the target EGR rate after filtering minus the actual EGR rate.

[0055] In the above scheme, the additional activation condition I includes:

[0056] (1) The absolute value of the EGR rate difference does not exceed the preset value X1 and the absolute value of the EGR rate difference change rate does not exceed the preset value Y1, and the mass flow rate of the exhaust gas entering the cylinder is dm. CylEGR With parameters When the difference exceeds the preset value Z1, item I control is activated;

[0057] (2) The absolute value of the EGR rate difference exceeds the preset value X2, or the absolute value of the EGR rate difference change rate exceeds the preset value Y2, or the mass flow rate of the exhaust gas entering the cylinder dm CylEGR and When the difference does not exceed the preset value Z2, item I control is not activated;

[0058] (3) In other cases, item I control maintains the previous state;

[0059] The I-item control is updated every sampling period, and its default state is that the I-item control is inactive; among them, the preset value X1 is less than the preset value X2, the preset value Y1 is less than the preset value Y2, and the preset value Z1 is greater than the preset value Z2; parameters According to the EGR valve inlet pressure p EGRInlet With atmospheric pressure p Amb ratio The result was obtained by looking up the table.

[0060] According to a second aspect of the present invention, a control device for entering a closed loop in an EGR system is provided, the device comprising:

[0061] The judgment unit is used to determine whether the EGR closed-loop enable condition is met; if yes, it enters the EGR closed-loop enable state; if no, it enters the EGR closed-loop disabled state.

[0062] The filtering unit is used to determine the target EGR rate and filter the target EGR rate under the EGR closed-loop enabled state to obtain the filtered target EGR rate.

[0063] The determination unit is used to determine the actual EGR rate, determine the EGR rate difference based on the actual EGR rate, the target EGR rate, and the filtered target EGR rate, and then determine the rate of change of the EGR rate difference based on the EGR rate difference.

[0064] The control unit is used to perform EGR closed-loop control using a PID control algorithm based on the EGR rate difference and the rate of change of the EGR rate difference; among them, the P-term and D-term controls are always active, while the I-term control is activated based on additional I-term activation conditions.

[0065] According to a third aspect of the present invention, a computer device is provided, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the control method for entering a closed loop of the EGR system as described in any one of the above.

[0066] According to a fourth aspect of the present invention, a computer-readable storage medium is provided having a computer program stored thereon, which, when executed by a processor, implements the steps of the control method for entering a closed loop in the EGR system described in any one of the above claims.

[0067] In summary, compared with the prior art, the above-described technical solutions conceived by this invention can achieve the following beneficial effects:

[0068] This invention optimizes EGR closed-loop control, not only by improving the closed-loop enable conditions but also by optimizing both the target EGR rate and the closed-loop control itself. This aims to respond as responsively as possible to the original target EGR demand while improving the accuracy of EGR rate control response. First, by setting the EGR closed-loop enable conditions, the EGR system is ensured to operate under suitable conditions, thereby improving system stability and reliability. Second, by filtering the target EGR rate, the impact of pressure boost response hysteresis is reduced, further enhancing the robustness of EGR rate control. Finally, the continuous activation of the P and D terms and the conditional activation of the I term in the PID control algorithm make EGR rate control more precise, effectively avoiding integral saturation and improving control flexibility and response speed. Attached Figure Description

[0069] Figure 1 A flowchart of a control method for entering a closed loop in an EGR system provided by an embodiment of the present invention;

[0070] Figure 2 This is a schematic diagram of a low-voltage EGR system structure provided in an embodiment of the present invention;

[0071] Figure 3 A flowchart of a control method for an EGR system to enter the EGR closed loop, provided by an embodiment of the present invention;

[0072] Figure 4 A schematic diagram of a control device for entering the closed loop of an EGR system provided in an embodiment of the present invention;

[0073] Figure 5 This is a schematic diagram of the structure of a computer device provided in an embodiment of the present invention.

[0074] In the diagram: 1-Air filter, 2-Mix valve, 3-Turbocharger compressor, 4-Throttle valve, 5-Engine, 6-Turbocharger turbine, 7-Catalyst, 8-Particulate filter, 9-EGR cooler, 10-EGR valve, 11-Temperature sensor, 12-Differential pressure sensor. Detailed Implementation

[0075] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0076] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0077] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0078] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0079] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0080] This invention improves the stability of EGR closed-loop control from the perspective of optimizing EGR closed-loop enable control. For example... Figure 2 As shown, the EGR system of the present invention includes: an air filter 1; a mixing valve 2 connected to the air filter for adjusting the pressure at the outlet of the EGR valve 10, increasing the pressure difference across the EGR valve 10, and extending two airflow passages from the mixing valve 2; a turbocharger compressor 3 connected to one of the airflow passages of the mixing valve 2; a throttle valve 4 connected to the turbocharger compressor 3; an engine 5 connected to the throttle valve 4 for compressing fresh air for boosting; a turbocharger turbine 6 connected to the engine 5 for controlling the opening of the exhaust bypass valve; a catalytic converter 7 connected to the turbine; and a particle size distribution device connected to the catalytic converter 7. Particulate matter trap 8; EGR cooler 9 installed on another airflow path of mixing valve 2, used to receive and cool the exhaust gas output from particulate matter trap 8, increasing exhaust gas flow rate; EGR valve 10 connected at one end to EGR cooler 9 and at the other end to mixing valve 2, used to control the exhaust gas flow rate entering the cylinder; temperature sensor 11 installed between EGR valve 10 and EGR cooler 9, used to detect the exhaust gas temperature entering EGR valve 10; differential pressure sensor 12 connected to EGR valve 10, used to detect the pressure at the inlet and outlet of EGR valve 10. The specific system architecture is as follows: Figure 2 As shown.

[0081] The control method for the EGR system to enter the closed loop according to the embodiments of the present invention, such as Figure 1 and Figure 3 As shown, it includes the following steps:

[0082] S1. Determine whether the EGR closed-loop enable condition is met; if yes, enter the EGR closed-loop enable state; if no, enter the EGR closed-loop disabled state.

[0083] In this embodiment, the EGR closed-loop enable condition must first be determined. The EGR closed-loop enable condition is as follows:

[0084] (1) No faults were found in any of the components of the EGR system;

[0085] (2) No fuel cut-off request occurred and the fuel cut-off recovery time exceeded the preset time, which is 0.3s in this example;

[0086] (3) The minimum EGR rate condition for EGR closed-loop enablement is satisfied;

[0087] (4) The engine speed is within the preset speed range, which is 750rpm to 5500rpm in this example;

[0088] (5) Intake air temperature is within the preset range. If the current state is EGR closed-loop disabled, then to enter the EGR closed-loop enabled state, the intake air temperature must be no lower than the minimum intake air temperature by 10°C. If the current state is EGR closed-loop enabled, then to exit the EGR system closed-loop enabled state, the intake air temperature must be 7°C lower than the minimum intake air temperature. If the current state is EGR closed-loop disabled, then to enter the EGR closed-loop enabled state, the intake air temperature must not exceed the maximum intake air temperature by 60°C. If the current state is EGR closed-loop enabled, then to exit the EGR system closed-loop enabled state, the intake air temperature must exceed the maximum intake air temperature by 65°C.

[0089] (6) Engine coolant temperature is within the preset range. If the current state is EGR closed-loop disabled, then enter the EGR closed-loop enabled state, which requires ensuring that the coolant temperature is not lower than the minimum coolant temperature of 60℃. If the current state is EGR closed-loop enabled, then exit the EGR system closed-loop enabled state, which requires ensuring that the coolant temperature is lower than the minimum coolant temperature of 55℃. If the current state is EGR closed-loop disabled, then enter the EGR closed-loop enabled state, which requires ensuring that the coolant temperature does not exceed the maximum coolant temperature of 115℃ (engine coolant temperature refers to the engine coolant temperature, which can reach above 130℃). If the current state is EGR closed-loop enabled, then exit the EGR system closed-loop enabled state, which requires ensuring that the coolant temperature exceeds the maximum coolant temperature of 120℃.

[0090] (7) Atmospheric temperature is within the preset range. If the current state is EGR closed-loop disabled, then enter the EGR closed-loop enabled state, which must ensure that it is not lower than the minimum atmospheric temperature, i.e., the minimum atmospheric temperature T. AmbTempMinEnbl In this example, C1 is set to 5℃. If the current state is EGR closed-loop enabled, exiting the EGR system closed-loop enabled state requires ensuring the temperature is below the minimum atmospheric temperature, i.e., the minimum atmospheric temperature T for exiting the enabled state. AmbTempMinDsblIn this example, C2 is set to 3℃; if the current state is EGR closed-loop disabled, then it enters the EGR closed-loop enabled state, which must ensure that it does not exceed the maximum atmospheric temperature, i.e., the maximum atmospheric temperature T. AmbTempMaxEnbl In this example, C3 is set to 55℃. If the current state is EGR closed-loop enabled, exiting the EGR system closed-loop enabled state requires ensuring that the maximum atmospheric temperature is exceeded, i.e., the maximum atmospheric temperature T for exiting the enabled state. AmbTempMaxDsbl In this example, C4 is set to 60℃;

[0091] (8) Atmospheric pressure p Amb Exceeding the preset minimum atmospheric pressure p AmbPreMinEnbl In this example, a pressure of 66 kPa is used, which allows entry into the EGR closed-loop enabled state; the atmospheric pressure is lower than the preset minimum atmospheric pressure p for deactivation. AmbPreMinDsbl In this example, the pressure is 64 kPa, so it is necessary to exit the EGR closed-loop enable state.

[0092] EGR closed-loop is enabled only when all of the above conditions are met; otherwise, EGR closed-loop is disabled.

[0093] In some embodiments, the minimum EGR rate condition for EGR closed-loop enable is as follows:

[0094] (1) When the difference between the target EGR rate and the minimum EGR rate (see the published patent CN202211212260.6 "Method, device, equipment and storage medium for adjusting minimum EGR rate") is greater than the preset value A, which is 0.02 in this example, the minimum EGR rate condition for EGR closed-loop enabling is met.

[0095] (2) When the difference between the target EGR rate and the minimum EGR rate is not greater than the preset value B, which is 0.01 in this example; and the absolute value of the difference between the target EGR rate and the actual EGR rate is not greater than the preset value, which is 0.1 in this example; then the minimum EGR rate condition for enabling EGR closed loop is not met.

[0096] (3) In other cases, the minimum EGR rate condition for enabling EGR closed-loop remains unchanged. For example, if the minimum EGR rate condition for enabling EGR closed-loop is met in the previous sampling period, the current sampling period will continue to maintain the state where the minimum EGR rate condition for enabling EGR closed-loop is met.

[0097] The minimum EGR rate for EGR closed-loop enable is in the default state when the vehicle is powered on. In the default state, the condition for minimum EGR rate for EGR closed-loop enable is not met.

[0098] S2. Under the EGR closed-loop enabled state, determine the target EGR rate and filter the target EGR rate to obtain the filtered target EGR rate.

[0099] In this embodiment, the target EGR rate is determined first, and then the filtered target EGR rate r is obtained. EGRDsrdFilter .

[0100] After EGR closed-loop is enabled, the EGR valve is controlled so that the actual EGR pressure follows the target EGR pressure. The purpose of this step is to determine the target EGR pressure. To further ensure the stability of pressure control after entering EGR closed-loop, and to improve the stability of EGR pressure control, the target EGR pressure is dynamically optimized.

[0101] This embodiment optimizes the target EGR pressure based on boost response to improve the system's pressure control responsiveness after EGR function activation, which is affected by boost hysteresis. Therefore, the target EGR rate is optimized based on the boost response, i.e., the target EGR rate is filtered to obtain the filtered target EGR rate r. EGRDsrdFilter :

[0102]

[0103] Where, r EGRDsrdFilter (N) represents the target EGR rate r after filtering in the Nth sampling period. EGRDsrdFilter r EGRDsrdFilter (N-1) represents the target EGR rate r after filtering in the N-1th sampling period. EGRDsrdFilter Δt is the sampling time, which is 10ms in this example, N = 1, 2, 3..., r EGRDsrdFilter (0) equals 0, which occurs when the vehicle is powered on. EGRDsrdRaw This is the currently publicly disclosed target EGR rate. EGRDsrdRaw (N) represents the target EGR rate of the Nth sampling period, and T is the filtering time, T = f(dk) T ).

[0104] The following explains how to obtain the filtering time T:

[0105] Turbocharger response time τ Boost This refers to the time it takes for the air-fuel mixture to flow from the turbocharger compressor to the throttle outlet. This part is obtained through bench calibration and can be used for different engine speeds (n). eng And different actual intake air densities rho entering the cylinder Act The value of τ is obtained by averaging multiple samples under different EGR rates. Boost It is determined by the engine speed n eng and the actual intake air density rho entering the cylinder Act It has been confirmed.

[0106] τ EGRThe time it takes for exhaust gas to flow from the EGR valve to the EGR exhaust gas junction (the EGR exhaust gas junction refers to the point where the EGR exhaust gas merges with fresh air; in this invention, the EGR exhaust gas junction can be seen at the mixing valve outlet in the diagram) is measured. This part is obtained through bench calibration and can be used at different engine speeds (n). eng And different actual intake air densities rho entering the cylinder Act The value of τ is obtained by averaging multiple samples under different EGR rates. EGR It is determined by the engine speed n eng and the actual intake air density rho entering the cylinder Act It has been confirmed.

[0107] The filter time coefficient for the target EGR rate is determined based on the above parameters. The aim is to optimize the target EGR rate while considering both boost response characteristics and EGR response characteristics, thereby improving the robustness of EGR rate control.

[0108] Calculate the filter time coefficient for the target EGR rate rate of change dk T :

[0109]

[0110] Among them, dk T (z) represents the rate of change dk in the previous sampling period. T k T (z) represents the filtering time coefficient k of the previous sampling period. T k at the initial time T (z) occurs at the EGR enable time, with a default value of 1, and the initial dk T (z) occurs at the EGR enable time, and its default value is 0, t c The time constant is 0.03s in this example. The purpose of calculating the rate of change of the filter time coefficient in this way is to avoid the rate of change being too rapid and affecting the target EGR rate. Large fluctuations in the filter time T can also cause the target EGR to change too quickly.

[0111] Table 1 Filtering Time Lookup Table

[0112]

[0113] It should be noted that, as shown in Table 1, if dk T When the value is less than -200, f(dk) T Take 0.15s; if dk T When the value is greater than 200, f(dk) T Take 0.18s; if f(dk) TWhen the value is in the middle of the table above, take the larger value in the table and look up the corresponding time.

[0114] S3. Determine the actual EGR rate, and determine the EGR rate difference based on the actual EGR rate, the target EGR rate, and the filtered target EGR rate. Then, determine the rate of change of the EGR rate difference based on the EGR rate difference.

[0115] S4. Based on the EGR rate difference and the rate of change of the EGR rate difference, use the PID control algorithm to perform EGR closed-loop control; among which, the P-term and D-term controls are always active, while the I-term control is activated based on the additional activation conditions of the I-term.

[0116] After the EGR closed-loop enable and target EGR rate are determined, the P and D terms in the PID algorithm are activated. However, the I term still needs to be evaluated for additional conditions before it can be activated; otherwise, the duty cycle of the I term's closed-loop control is 0. The control methods for the P and D terms are the same as those for conventional PD control, but there are two points for optimization and improvement:

[0117] A) Optimizing the EGR rate difference (the difference between the target EGR rate and the actual EGR rate) and the rate of change of the EGR rate difference can, on the one hand, respond to the original target EGR requirement as much as possible, and on the other hand, improve the response accuracy of EGR rate control.

[0118] The method for determining the EGR rate difference is as follows:

[0119] (1) Target EGR rate r EGRDsrdRaw Greater than the target EGR rate r after filtering EGRDsrdFilter The EGR rate difference is:

[0120] ① The actual EGR rate is greater than the target EGR rate r EGRDsrdRaw At that time, the EGR rate difference is equal to the currently publicly disclosed target EGR rate r. EGRDsrdRaw Subtract the actual EGR rate;

[0121] ② The actual EGR rate is less than the target EGR rate r after filtering. EGRDsrdFilter At that time, the EGR rate difference is equal to the filtered target EGR rate r. EGRDsrdFilter Subtract the actual EGR rate;

[0122] ③ In other cases, the EGR rate difference is equal to 0; the priority decreases from ① to ③.

[0123] (2) Target EGR rate r EGRDsrdRaw Less than the target EGR rate r after filtering EGRDsrdFilter At that time, the EGR rate difference is:

[0124] ① Actual EGR rate is less than target EGR rate r EGRDsrdRaw At that time, the EGR rate difference equals the target EGR rate r. EGRDsrdRawSubtract the actual EGR rate;

[0125] ② The actual EGR rate is greater than the target EGR rate r after filtering. EGRDsrdFilter At that time, the EGR rate difference is equal to the filtered target EGR rate r. EGRDsrdFilter Subtract the actual EGR rate;

[0126] ③ In other cases, the EGR rate difference is equal to 0; the priority decreases from ① to ③.

[0127] (3) In other cases, the EGR rate difference is equal to the filtered target EGR rate r. EGRDsrdFilter Subtract the actual EGR rate.

[0128] Furthermore, the rate of change of the EGR rate difference is obtained. Finally, based on the EGR rate difference and its rate of change, PID control is performed to obtain real-time short-term fuel correction. PID control is existing technology and will not be elaborated upon here.

[0129] B) Item I requires an additional condition for evaluation:

[0130] 1) The absolute value of the EGR rate difference does not exceed the preset value X1 (0.02 in this example) and the absolute value of the EGR rate difference change rate does not exceed the preset value Y1 (0.01 / 10ms in this example), and the mass flow rate dm of the exhaust gas entering the cylinder is... CylEGR and When the difference exceeds the preset value Z1 (0.1 g / s in this example), item I control is activated; where p EGRInlet This refers to the inlet pressure of the EGR valve.

[0131] 2) The absolute value of the EGR rate difference exceeds the preset value X2 (0.03 in this example) or the absolute value of the EGR rate difference change rate exceeds the preset value Y2 (0.02 / 10ms in this example), or the mass flow rate dm of the exhaust gas entering the cylinder... CylEGR and If the difference does not exceed the preset value Z2 (0.05 g / s in this example), then item I control will not be activated;

[0132] 3) In other cases, the activation or deactivation of item I remains unchanged from the previous state, and it is also updated every sampling period (the sampling period is 10ms in this example). The default state is that item I control is not activated.

[0133] in, The information was obtained by looking up Table 2.

[0134] Table 2 Parameter Lookup Table

[0135]

[0136] The purpose of setting the above additional activation condition for item I is to prevent the accumulation of excessively large values ​​in item I when the difference in EGR rates is too large or the rate of change of the difference in EGR rates is too large. This could easily lead to integral saturation of the closed-loop control. This is to mitigate the integral saturation of item I. When the exhaust gas flow rate is too low, the integral term can accumulate excessively, easily causing integral saturation of item I. The lower the inlet pressure of the EGR valve, the more important the flow rate controlled by EGR becomes. The purpose of referencing atmospheric pressure is simply to make corrections to account for the effects of different atmospheric pressures, thereby ensuring standardized control.

[0137] After the I-term is activated, the I-term control method is the same as the I-term algorithm in the conventional PID algorithm.

[0138] The above completes the description of the control method for entering the EGR closed loop. A flowchart of the method can be found here. Figure 1 and Figure 3 .

[0139] The control device for the EGR system entering the closed loop based on the above embodiments, such as Figure 4 As shown, it includes:

[0140] The judgment unit 501 is used to determine whether the EGR closed-loop enable condition is met; if yes, it enters the EGR closed-loop enable state; if no, it enters the EGR closed-loop disabled state.

[0141] The filtering unit 502 is used to determine the target EGR rate and filter the target EGR rate in the EGR closed-loop enabled state to obtain the filtered target EGR rate.

[0142] The determination unit 503 is used to determine the actual EGR rate, determine the EGR rate difference based on the actual EGR rate, the target EGR rate, and the filtered target EGR rate, and then determine the EGR rate difference change rate based on the EGR rate difference.

[0143] The control unit 504 is used to perform EGR closed-loop control using a PID control algorithm based on the EGR rate difference and the rate of change of the EGR rate difference; wherein, the P-term and D-term controls are always active, while the I-term control is activated based on the additional activation conditions of the I-term.

[0144] like Figure 5 The diagram shown is a structural schematic of a computer device provided in an embodiment of the present invention, such as a smartphone, tablet computer, laptop computer, desktop computer, rack server, blade server, tower server, or cabinet server (including a standalone server or a server cluster composed of multiple servers), etc., capable of executing programs. The computer device 20 in this embodiment includes, but is not limited to, a memory 21 and a processor 22 that can be interconnected via a system bus, such as... Figure 5 As shown. It should be noted that, Figure 5 Only a computer device 20 with components 21-22 is shown; however, it should be understood that it is not required to implement all of the components shown, and more or fewer components may be implemented instead.

[0145] In this embodiment, the memory 21 (i.e., the readable storage medium) includes flash memory, hard disk, multimedia card, card-type memory (e.g., SD or DX memory), random access memory (RAM), static random access memory (SRAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), and programmable read-only memory (PROM). The memory 21 can also be an external storage device of the computer device 20, such as a plug-in hard disk, smart media card (SMC), secure digital (SD) card, flash card, etc., equipped on the computer device 20. Of course, the memory 21 can also include both internal storage units and external storage devices of the computer device 20. In this embodiment, the memory 21 is typically used to store the operating system and various application software installed on the computer device 20, such as the program code of the control method for the EGR system to enter the closed loop in the method embodiment. Furthermore, the memory 21 can also be used to temporarily store various types of data that have been output or will be output.

[0146] In some embodiments, processor 22 may be a central processing unit (CPU), controller, microcontroller, microprocessor, or other data processing chip. This processor 22 is typically used to control the overall operation of computer device 20. In this embodiment, processor 22 is used to run program code stored in memory 21 or process data, for example, to run a device storing program code for a control method for the EGR system to enter a closed loop, in order to implement the control method for the EGR system to enter a closed loop in the method embodiment.

[0147] This application also provides a computer-readable storage medium, such as flash memory, hard disk, multimedia card, card-type memory (e.g., SD or DX memory), random access memory (RAM), static random access memory (SRAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), programmable read-only memory (PROM), magnetic memory, disk, optical disk, server, app store, etc., which stores a computer program. When the program is executed by a processor, it implements the corresponding function. In this embodiment, the computer-readable storage medium is used to store program code for a control method for an EGR system to enter a closed loop. When executed by a processor, it implements the control method for an EGR system to enter a closed loop as described in the method embodiment.

[0148] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0149] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0150] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0151] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0152] In summary, this invention proposes a control method, device, equipment, and medium for EGR system entering closed loop. The method proposes an EGR enable condition judgment method, a target EGR rate setting method, and an EGR closed-loop PID control method. By optimizing the EGR closed-loop control, not only are the closed-loop enable conditions optimized, but the target EGR rate and closed-loop control are also optimized to respond to the original target EGR demand as much as possible, while also improving the EGR rate control response accuracy.

[0153] It should be noted that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0154] It should be noted that, depending on the implementation needs, the various steps / components described in this application can be broken down into more steps / components, or two or more steps / components or parts of the operation of steps / components can be combined into new steps / components to achieve the purpose of this invention.

[0155] Those skilled in the art will readily understand that the above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A control method for an EGR system to enter a closed loop, characterized in that, The method includes: Determine if the EGR closed-loop enable condition is met; if yes, enter the EGR closed-loop enable state; if no, enter the EGR closed-loop disabled state. Under EGR closed-loop enabled state, the target EGR rate is determined and filtered to obtain the filtered target EGR rate; Determine the actual EGR rate, determine the EGR rate difference based on the actual EGR rate, the target EGR rate, and the filtered target EGR rate, and then determine the rate of change of the EGR rate difference based on the EGR rate difference. Based on the EGR rate difference and the rate of change of the EGR rate difference, a PID control algorithm is used for EGR closed-loop control; among them, the P-term and D-term controls are always active, while the I-term control is activated based on the additional activation conditions of the I-term. The EGR rate difference is determined based on the actual EGR rate, the target EGR rate, and the filtered target EGR rate, including: (1) If the target EGR rate is greater than the filtered target EGR rate, then the EGR rate difference is: ① When the actual EGR rate is greater than the target EGR rate, the difference in EGR rates is equal to the target EGR rate minus the actual EGR rate; ② When the actual EGR rate is less than the target EGR rate after filtering, the EGR rate difference is equal to the target EGR rate after filtering minus the actual EGR rate; ③ In other cases, the EGR rate difference is equal to 0; The priority of the above three situations decreases in the following order; (2) If the target EGR rate is less than the filtered target EGR rate, then the EGR rate difference is: ① When the actual EGR rate is less than the target EGR rate, the difference in EGR rates is equal to the target EGR rate minus the actual EGR rate; ② When the actual EGR rate is greater than the target EGR rate after filtering, the EGR rate difference is equal to the target EGR rate after filtering minus the actual EGR rate; ③ In other cases, the EGR rate difference is equal to 0; The priority of the above three situations decreases in the following order; (3) In other cases, the EGR rate difference is equal to the target EGR rate after filtering minus the actual EGR rate.

2. The control method for entering the closed loop of the EGR system according to claim 1, characterized in that, EGR closed-loop enable conditions include: No faults were found in any of the components of the EGR system; No fuel cut-off request was received and the fuel cut-off recovery time exceeded the preset time; The minimum EGR rate condition for EGR closed-loop enable is satisfied; The engine speed is within the preset speed range; Intake air temperature is within the preset range; Engine coolant temperature is within the preset range; Atmospheric temperature is within the preset range; Atmospheric pressure meets the preset threshold. The EGR closed-loop enable condition is met when all of the above conditions are met simultaneously; otherwise, the EGR closed-loop enable condition is not met.

3. The control method for entering the closed loop of the EGR system according to claim 2, characterized in that, The minimum EGR rate condition for enabling EGR closed-loop control is determined as follows: When the difference between the target EGR rate and the minimum EGR rate is greater than the preset value A, the condition for enabling the minimum EGR rate in the EGR closed loop is met. If the difference between the target EGR rate and the minimum EGR rate is not greater than the preset value B, and the absolute value of the difference between the target EGR rate and the actual EGR rate is not greater than the preset value, then the minimum EGR rate condition for enabling the EGR closed loop is not met; where the preset value A is greater than the preset value B. In other cases, the minimum EGR rate condition for EGR closed-loop enable remains in the previous state; when the vehicle is powered on, the minimum EGR rate condition for EGR closed-loop enable is not met by default.

4. The control method for entering the closed loop of the EGR system according to claim 2, characterized in that, Intake air temperature within the preset range includes: If the current state is EGR closed-loop disabled, then enter the EGR closed-loop enabled state, ensuring that the intake air temperature is not lower than the first minimum intake air temperature and does not exceed the first maximum intake air temperature; if the current state is EGR closed-loop enabled, then exit the EGR closed-loop enabled state and enter the EGR closed-loop disabled state, ensuring that the intake air temperature is lower than the second minimum intake air temperature or exceeds the second maximum intake air temperature; wherein, the second minimum intake air temperature is less than the first minimum intake air temperature, less than the first maximum intake air temperature, and less than the second maximum intake air temperature. Similarly, engine coolant temperature within the preset range includes: If the current state is EGR closed-loop disabled, then enter the EGR closed-loop enabled state, ensuring that the engine coolant temperature is not lower than the first minimum coolant temperature and does not exceed the first maximum coolant temperature; if the current state is EGR closed-loop enabled, then exit the EGR closed-loop enabled state and enter the EGR closed-loop disabled state, ensuring that the engine coolant temperature is lower than the second minimum coolant temperature or exceeds the second maximum coolant temperature; wherein, the second minimum coolant temperature is less than the first minimum coolant temperature, less than the first maximum coolant temperature, and less than the second maximum coolant temperature. Similarly, atmospheric temperature within the preset range includes: If the current state is EGR closed-loop disabled, then enter the EGR closed-loop enabled state, ensuring that the atmospheric temperature is not lower than the first minimum atmospheric temperature and does not exceed the first maximum atmospheric temperature; if the current state is EGR closed-loop enabled, then exit the EGR closed-loop enabled state and enter the EGR closed-loop disabled state, ensuring that the atmospheric temperature is lower than the second minimum atmospheric temperature or exceeds the second maximum atmospheric temperature; wherein, the second minimum atmospheric temperature is less than the first minimum atmospheric temperature, less than the first maximum atmospheric temperature, and less than the second maximum atmospheric temperature.

5. The control method for entering the closed loop of the EGR system according to claim 2, characterized in that, Atmospheric pressure meeting preset thresholds includes: If the atmospheric pressure exceeds the preset minimum atmospheric pressure for enabling, the system enters the EGR closed-loop enabled state; if the atmospheric pressure is lower than the preset minimum atmospheric pressure for deactivating, the system exits the EGR closed-loop enabled state and enters the EGR closed-loop disabled state; wherein, the preset minimum atmospheric pressure for enabling is greater than the preset minimum atmospheric pressure for deactivating.

6. The control method for entering the closed loop of the EGR system according to claim 1, characterized in that, The target EGR rate is filtered to obtain the filtered target EGR rate, including: For each sampling period, determine the filtering time; The target EGR rate after filtering in the current sampling period is determined based on the target EGR rate of the current sampling period, the target EGR rate of the previous sampling period, the sampling time interval, the filtering time, and the target EGR rate after filtering in the previous sampling period.

7. The control method for entering the closed loop of the EGR system according to claim 6, characterized in that, Determine the filtering time, including: Determine the turbocharger response time The time it takes for exhaust gas to flow from the EGR valve to the EGR exhaust gas junction point Among them, the turbocharger response time The time it takes for the air-fuel mixture to flow from the turbocharger compressor to the throttle outlet; Based on turbocharger response time The time it takes for exhaust gas to flow from the EGR valve to the EGR exhaust gas junction point Determine the filter time coefficient for the target EGR rate ; Based on the filter time coefficient of the target EGR rate Determine the rate of change of the filter time coefficient for the target EGR rate. : In the formula, The rate of change of the filter time coefficient for the target EGR rate in the current sampling period. The rate of change of the filter time coefficient for the target EGR rate in the previous sampling period. The filter time coefficient is the target EGR rate for the current sampling period. The filter time coefficient is the target EGR rate of the previous sampling period. The sampling time interval, It is a time constant; The rate of change of the filter time coefficient based on the target EGR rate The filtering time is determined by looking up a table.

8. The control method for entering the closed loop of the EGR system according to claim 7, characterized in that, turbocharger response time The time it takes for exhaust gas to flow from the EGR valve to the EGR exhaust gas junction point All are determined by engine speed and the actual intake air density entering the cylinder Calibration determined; The specific calibration method is as follows: at different engine speeds And different actual intake air densities entering the cylinder The result is obtained by averaging multiple samples under different EGR rates.

9. The control method for entering the closed loop of the EGR system according to claim 1, characterized in that, The additional activation condition includes: (1) The absolute value of the EGR rate difference does not exceed the preset value X1 and the absolute value of the EGR rate difference change rate does not exceed the preset value Y1 and the mass flow rate of the exhaust gas entering the cylinder With parameters When the difference exceeds the preset value Z1, item I control is activated; (2) The absolute value of the EGR rate difference exceeds the preset value X2 or the absolute value of the EGR rate difference change rate exceeds the preset value Y2 or the mass flow rate of the exhaust gas entering the cylinder. and When the difference does not exceed the preset value Z2, item I control is not activated; (3) In other cases, control item I maintains the previous state; The I-item control is updated every sampling period, and its default state is that the I-item control is inactive; among them, the preset value X1 is less than the preset value X2, the preset value Y1 is less than the preset value Y2, and the preset value Z1 is greater than the preset value Z2; parameters Based on the EGR valve inlet pressure With atmospheric pressure ratio The result was obtained by looking up the table.

10. A control device for entering a closed loop in an EGR system, characterized in that, The device includes: The judgment unit is used to determine whether the EGR closed-loop enable condition is met; if yes, it enters the EGR closed-loop enable state; if no, it enters the EGR closed-loop disabled state. The filtering unit is used to determine the target EGR rate and filter the target EGR rate under the EGR closed-loop enabled state to obtain the filtered target EGR rate. The determining unit is used to determine the actual EGR rate, determine the EGR rate difference based on the actual EGR rate, the target EGR rate, and the filtered target EGR rate, and then determine the rate of change of the EGR rate difference based on the EGR rate difference; wherein, determining the EGR rate difference based on the actual EGR rate, the target EGR rate, and the filtered target EGR rate includes: (1) If the target EGR rate is greater than the filtered target EGR rate, then the EGR rate difference is: ① When the actual EGR rate is greater than the target EGR rate, the difference in EGR rates is equal to the target EGR rate minus the actual EGR rate; ② When the actual EGR rate is less than the target EGR rate after filtering, the EGR rate difference is equal to the target EGR rate after filtering minus the actual EGR rate; ③ In other cases, the EGR rate difference is equal to 0; The priority of the above three situations decreases in the following order; (2) If the target EGR rate is less than the filtered target EGR rate, then the EGR rate difference is: ① When the actual EGR rate is less than the target EGR rate, the difference in EGR rates is equal to the target EGR rate minus the actual EGR rate; ② When the actual EGR rate is greater than the target EGR rate after filtering, the EGR rate difference is equal to the target EGR rate after filtering minus the actual EGR rate; ③ In other cases, the EGR rate difference is equal to 0; The priority of the above three situations decreases in the following order; (3) In other cases, the EGR rate difference is equal to the filtered target EGR rate minus the actual EGR rate; The control unit is used to perform EGR closed-loop control using a PID control algorithm based on the EGR rate difference and the rate of change of the EGR rate difference; among them, the P-term and D-term controls are always active, while the I-term control is activated based on additional I-term activation conditions.

11. A computer device, characterized in that, The system includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the control method for entering a closed loop for the EGR system according to any one of claims 1 to 9.

12. A computer-readable storage medium, characterized in that, It stores a computer program, which, when executed by a processor, implements the steps of the control method for entering a closed loop in the EGR system according to any one of claims 1 to 9.

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