An egr control method and system for improving engine power and safety

Abstract

The application discloses an EGR control method and system for improving engine power and safety, which comprises the following steps: determining whether the EGR closed-loop enabling time condition is met according to the relationship between the time when the vehicle transmission system enters the parallel state from the series state and the preset time, the target EGR rate and the minimum EGR rate; wherein the preset time is updated in each driving cycle through a self-learning correction coefficient; if the EGR closed-loop enabling time condition is met, determining whether the EGR closed-loop enabling minimum EGR rate condition is met according to the target EGR rate and the minimum EGR rate; if the EGR closed-loop enabling minimum EGR rate condition is met, determining whether to enter the EGR closed-loop enabling, and performing the EGR closed-loop control after the EGR closed-loop enabling, and controlling the mixed valve and the EGR valve to make the actual EGR rate follow the target EGR rate based on the target EGR rate and the actual EGR rate. The application optimizes the EGR closed-loop enabling condition, and improves the engine power and the control stability.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of engine control, in particular to an EGR control method and system for improving engine power and safety. BACKGROUND

[0002] Exhaust gas recirculation (EGR) is a process in which exhaust gas is taken from the exhaust system and introduced into the intake system. Studies have shown that EGR systems have certain advantages in improving emissions, reducing fuel consumption and improving anti-knock ability. The control of the mixing valve in the low-pressure EGR system is particularly important for improving the effect of EGR rate.

[0003] Due to the hysteresis of the system, EGR rate may cause control actuator oscillation when it enters the minimum EGR rate region, and even the EGR system is unstable. Based on this, the present application mainly optimizes the judgment method of EGR enable condition in hybrid vehicle, optimizes the EGR closed-loop enable condition, and improves the performance of engine power and control stability. SUMMARY

[0004] The technical problem to be solved by the present application is to provide an EGR control method and system for improving engine power and safety in view of the defects in the prior art.

[0005] The technical scheme adopted by the present application to solve the technical problem is:

[0006] The present application provides an EGR control method for improving engine power and safety, comprising:

[0007] According to the relationship between the time when the vehicle transmission system enters the parallel state from the series state and the preset time, in combination with the target EGR rate and the minimum EGR rate, it is determined whether the EGR closed-loop enable time condition is met; wherein the preset time is updated in each driving cycle by a self-learning correction coefficient;

[0008] If the EGR closed-loop enable time condition is met, it is determined whether the EGR closed-loop enable minimum EGR rate condition is met according to the target EGR rate and the minimum EGR rate;

[0009] If the EGR closed-loop enable minimum EGR rate condition is met, it is determined whether to enter the EGR closed-loop enable, and after the enable, the EGR closed-loop control is performed, based on the target EGR rate and the actual EGR rate, the mixing valve and the EGR valve are controlled to act so that the actual EGR rate follows the target EGR rate.

[0010] Further, the method for determining whether the EGR closed-loop enable time condition is met comprises:

[0011] If the time from the series state to the parallel state is not more than a preset time T0, and the difference between the target EGR rate and the minimum EGR rate is not more than a certain threshold, the EGR closed-loop enabling time condition is met; otherwise:

[0012] If the series state is met, and the difference between the target EGR rate and the minimum EGR rate exceeds a certain threshold, and the continuous meeting time of the engine torque fluctuation correction coefficient exceeding a preset value exceeds a certain threshold time T1, the EGR closed-loop enabling time condition is not met; otherwise:

[0013] The EGR closed-loop enabling time condition is met in the state of maintaining the previous state, and the default state is that the EGR closed-loop enabling time condition is met.

[0014] Further, the engine torque fluctuation correction coefficient of the present application is determined according to the difference between the engine requested fire path torque and the actual fire path torque and the first-order low-pass filtered torque difference.

[0015] Further, the method for determining whether the EGR closed-loop enabling minimum EGR rate condition is met includes:

[0016] When the difference between the target EGR rate and the minimum EGR rate is greater than a preset value, the EGR closed-loop enabling minimum EGR rate condition is met.

[0017] Further, the method for determining whether the EGR closed-loop enabling minimum EGR rate condition is met includes:

[0018] When the difference between the target EGR rate and the minimum EGR rate is not greater than a preset value, and the absolute value of the difference between the target EGR rate and the actual EGR rate is not greater than a preset value, and the EGR closed-loop enabling time condition is not met, the EGR closed-loop enabling minimum EGR rate condition is not met.

[0019] The default state is that the EGR closed-loop enabling minimum EGR rate condition is not met when the vehicle is powered on.

[0020] Further, the method for determining whether to enter the EGR closed-loop enabling includes:

[0021] No related faults of each part of the EGR system occur;

[0022] No oil interruption request occurs and the oil interruption recovery time exceeds a preset time;

[0023] The EGR closed-loop enabling minimum EGR rate condition is met;

[0024] The engine speed is within a preset speed range;

[0025] The intake air temperature is within a preset range;

[0026] The engine water temperature is within a preset range;

[0027] The atmospheric temperature is within a preset range;

[0028] The atmospheric pressure is within a preset range;

[0029] The EGR closed-loop state is allowed only when the above conditions are met simultaneously, otherwise the EGR closed-loop state is not allowed.

[0030] Further, the preset time T0 optimization method of the present application comprises:

[0031] At a time when the T0 time has not ended, assuming that there is still T0' time left at this time, T0' is not greater than T0, then the T0' time is optimized to obtain a new T01'; the formula is:

[0032] T01'=max{T0'×[1+f(Cnt LowKnock )+f(Cnt MediumKnock )+f(Cnt HighKnock )]×(1+r T0 ),0}

[0033] Wherein, Cnt LowKnock , Cnt MediumKnock , Cnt HighKnock are knock intensity corresponding to knock occurrence cumulative number of low intensity level, medium intensity level and high intensity level respectively, r T0 is a time T0 self-learning correction coefficient, its default value is 0, and is saved after the vehicle is powered off; f(Cnt LowKnock ), f(Cnt MediumKnock ), f(Cnt HighKnock ) are obtained through calibration.

[0034] Further, the threshold time T1 optimization method of the present application comprises:

[0035] At a time when the T1 time has not ended, assuming that there is still T1' time left at this time, T1' is not greater than T1, then the T1' time is optimized to obtain a new T11'; the formula is:

[0036]

[0037] Wherein, is an engine torque fluctuation correction coefficient r TrqErr cumulative value, the starting time of its accumulation is: when the vehicle state is in series state, and the difference between the target EGR rate and the minimum EGR rate does not exceed a certain threshold; r TrqErr0 is the engine torque fluctuation correction coefficient r TrqErr at the starting time;

[0038] The engine torque fluctuation correction coefficient r is obtained based on T1 a time T1 self-learning correction coefficient.

[0039] Further, the engine torque fluctuation correction coefficient r TrqErr of the present application is obtained by the method comprising:

[0040]

[0041] wherein M TrqErr is the difference between the engine requested firing path torque and the actual firing path torque, M TrqErrFilter is the first-order low-pass filtered torque difference.

[0042] Further, the method for obtaining the filtered torque difference of the present application comprises:

[0043] M TrqErrFilter (N)=K TrqErr ×[M TrqErr (N)-M TrqErrFilter (N-1)]+M TrqErrFilter (N-1)

[0044] wherein M TrqErr (N) is the torque difference in the Nth sampling period, M TrqErrFilter (N) is the filtered torque difference in the Nth sampling period, M TrqErrFilter (N-1) is the filtered torque difference in the (N-1)th sampling period, and N=1, 2, 3…; the sampling period interval is Δt, and K TrqErr is the coefficient.

[0045] Further, the learning method of the self-learning correction coefficient of the present application comprises:

[0046] the learning method of r T0 comprises:

[0047] If T01'-T0' is greater than a preset value, and the continuous occurrence frequency CNT1 exceeds a preset value C1, then r T0 is set as: r T0 =r T0 (z)+0.02, wherein r T0 (z) is the time T0 learning value stored in the last learning, and CNT1 is cleared at the same time;

[0048] If T01'-T0' is not greater than a preset value, and the continuous occurrence frequency CNT2 exceeds a preset value C2, then r T0 is set as: r T0 =r T0 (z)-0.01.

[0049] rT1 Learning methods:

[0050] If T1'-T11' is greater than the preset value C3, and the number of consecutive occurrences CNT2 exceeds the preset value, then r will be... T1 Set to: r T1 =r T1 (z)+0.01, and simultaneously clear CNT2 to zero;

[0051] If T1'-T11' is not greater than the preset value C4, and the number of consecutive occurrences CNT2 exceeds the preset value, then r will be... T1 Set to: r T1 =r T1 (z)-0.005.

[0052] This invention provides an EGR control system for improving engine power and safety, comprising:

[0053] Memory, used to store executable computer programs;

[0054] When the processor executes an executable computer program stored in memory, it implements the aforementioned EGR control method for improving engine power and safety.

[0055] The beneficial effects of this invention are:

[0056] 1. This invention considers optimizing the EGR closed-loop enabling conditions in hybrid vehicles based on different transmission states, from the perspective of power and torque stability, thereby further assisting in improving the engine's power and control stability performance.

[0057] 2. This invention determines whether the EGR closed-loop enable time condition is met based on the relationship between the time it takes for the vehicle transmission system to transition from a series state to a parallel state and a preset time, combined with the target EGR rate and the minimum EGR rate. In the determination process, a preset time updated by a self-learning correction coefficient is introduced, which improves the control accuracy and performance of each driving cycle.

[0058] 3. This invention proposes the conditions for determining the minimum EGR rate for EGR enable activation and EGR closed-loop enable.

[0059] 4. This invention proposes a time T0 learning value r T0 The self-learning coefficient r of time T1 T1 The settings are configured, and different situations and conditions are applied to r. T0 and r T1 Optimization learning improved control precision and enhanced engine power. Attached Figure Description

[0060] The application will be further described below in connection with the accompanying drawings and embodiments, in which:

[0061] Figure 1 is a schematic diagram of the system structure of the embodiment of the application with EGR;

[0062] 1, air filter; 2, mixing valve; 3, compressor; 4, throttle; 5, engine; 6, turbine; 7, catalytic converter; 8, particulate trap; 9, EGR cooler; 10, EGR valve; 11, temperature sensor; 12, differential pressure sensor.

[0063] Figure 2 is a whole method flowchart of the embodiment of the application;

[0064] Figure 3 is a flowchart of the minimum EGR rate condition enabled by EGR closed loop of the embodiment of the application;

[0065] Figure 4 is a flowchart of the time condition enabled by EGR closed loop of the embodiment of the application;

[0066] Figure 5 is a system block diagram of the embodiment of the application. DETAILED DESCRIPTION

[0067] In order to make the purpose, technical scheme and advantages of the application more clear, the application will be further described below in connection with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the application and do not limit the application.

[0068] Embodiment 1

[0069] Before describing the content of the embodiment of the application, a general description of the system structure with EGR is given as a basis for the subsequent embodiments.

[0070] As Figure 1As shown, the EGR system structure of the embodiment of the present application comprises: an air filter 1; a mixing valve 2 connected to the air filter, used to adjust the pressure at the outlet of an EGR valve 10, to increase the pressure difference across the EGR valve 10, and two gas flow paths extending from the mixing valve 2; a compressor 3 connected to one of the gas flow paths of the mixing valve 2; a throttle valve 4 connected to the compressor 3; an engine 5 connected to the throttle valve 4, used to compress fresh air for supercharging; a turbine 6 connected to the engine 5, used to control the opening degree of a waste gas bypass valve; a catalyst 7 connected to the turbine 6; a particulate trap 8 connected to the catalyst 7; an EGR cooler 9 installed on the other gas flow path of the mixing valve 2, used to receive and cool the waste gas output by the particulate trap 8, and to increase the waste gas flow; an EGR valve 10 having one end connected to the EGR cooler 9 and the other end connected to the mixing valve 2, used to control the waste gas flow into the cylinder; a temperature sensor 11 installed between the EGR valve 10 and the EGR cooler 9, used to detect the temperature of the waste gas entering the EGR valve 10; and a pressure difference sensor 12 connected to the EGR valve 10, used to detect the pressure at the inlet and outlet of the EGR valve 10.

[0071] As shown, the EGR control method for improving engine power and safety of the embodiment of the present application comprises the following control procedures and determination conditions: Figure 2

[0072] Step one, according to the relationship between the time when the vehicle transmission system enters the parallel state from the series state and the preset time, in combination with the target EGR rate and the minimum EGR rate, determine whether the EGR closed loop enabling time condition is met; wherein the preset time is updated in each driving cycle by a self-learning correction coefficient;

[0073] Step two, if the EGR closed loop enabling time condition is met, determine whether the EGR closed loop enabling minimum EGR rate condition is met according to the target EGR rate and the minimum EGR rate;

[0074] Step three, if the EGR closed loop enabling minimum EGR rate condition is met, determine whether to enter the EGR closed loop enabling, and after enabling, perform EGR closed loop control, based on the target EGR rate and the actual EGR rate, control the mixing valve and the EGR valve to act so that the actual EGR rate follows the target EGR rate.

[0075] The method of the embodiment of the present application considers that in the hybrid vehicle, based on different transmission states (series state and parallel state), the EGR closed loop enabling conditions are optimized from the perspective of power and torque stability, thereby further assisting to improve the performance of engine power and control stability.

[0076] Embodiment 2

[0077] As shown, Figure 3 ​As shown, the embodiment of the present application provides a method for determining the minimum EGR rate condition of EGR closed loop enablement based on embodiment 1, which specifically comprises:

[0078] 1) When the difference between the target EGR rate and the minimum EGR rate (see the published patent CN202211212260.6 "Method and device for adjusting minimum EGR rate, equipment and storage medium") is greater than a preset value A, A=C1, C1 is 0.02 in this example. Then the minimum EGR rate condition of EGR closed loop enablement is met;

[0079] 2) Condition 2.1, when the difference between the target EGR rate and the minimum EGR rate r EGRRateMinFinal is not greater than a preset value B, B=C2, C2 is 0.01 in this example; Condition 2.2, and the absolute value of the difference between the target EGR rate and the actual EGR rate is not greater than a preset value, which is 0.1 in this example; Condition 2.3, and the EGR closed loop enablement time condition is not met. Then the minimum EGR rate condition of EGR closed loop enablement is not met;

[0080] 3) In other cases, the minimum EGR rate condition of EGR closed loop enablement is maintained in the last state. When the vehicle is powered on, it is the default state, and the default state is that the minimum EGR rate condition of EGR closed loop enablement is not met.

[0081] Embodiment 3

[0082] The embodiment of the present application provides a method for determining the EGR closed loop state based on embodiments 1 and 2, which specifically comprises:

[0083] 1) No related faults of EGR system parts occur;

[0084] 2) No oil cut request occurs and the oil cut recovery time exceeds a preset time, which is 0.3s in this example;

[0085] 3) The minimum EGR rate condition of EGR closed loop enablement is met;

[0086] 4) The engine speed is within a preset speed range, which is 750rpm-5500rpm in this example;

[0087] 5) The intake temperature is within a preset range. If the current state is EGR closed loop not enabled, enter the EGR closed loop state, which needs to be ensured not lower than the minimum intake temperature of 10℃. If the current state is EGR closed loop enabled state, exit the EGR system closed loop enablement state, which needs to be ensured lower than the minimum intake temperature of 7℃. If the current state is EGR closed loop not enabled, enter the EGR closed loop state, which needs to be ensured not exceeding the maximum intake temperature of 60℃. If the current state is EGR closed loop enabled state, exit the EGR system closed loop enablement state, which needs to be ensured exceeding the maximum intake temperature of 65℃;

[0088] 6) Engine water temperature is in the preset range. If the current state is EGR closed loop not enabled, enter the EGR closed loop state, and need to ensure that the minimum water temperature is not less than 60℃, if the current state is EGR closed loop enabled state, exit the EGR system closed loop enabled state and need to ensure that the minimum water temperature is less than 55℃; If the current state is EGR closed loop not enabled, enter the EGR closed loop state, and need to ensure that the maximum water temperature is not more than 115℃; If the current state is EGR closed loop enabled state, exit the EGR system closed loop enabled state and need to ensure that the maximum water temperature is more than 120℃;

[0089] 7) Atmospheric temperature is in the preset range. If the current state is EGR closed loop not enabled, enter the EGR closed loop state, and need to ensure that the minimum atmospheric temperature is not less than 5℃, if the current state is EGR closed loop enabled state, exit the EGR system closed loop enabled state and need to ensure that the minimum atmospheric temperature is less than 3℃; If the current state is EGR closed loop not enabled, enter the EGR closed loop state, and need to ensure that the maximum atmospheric temperature is not more than 55℃; If the current state is EGR closed loop enabled state, exit the EGR system closed loop enabled state and need to ensure that the maximum atmospheric temperature is more than 60℃;

[0090] 8) Atmospheric pressure exceeds 66kPa to allow EGR closed loop enabled condition, atmospheric temperature is lower than 64kPa to need to exit EGR closed loop enabled condition

[0091] The above conditions are allowed to enter the EGR closed loop state, otherwise the EGR closed loop state is not allowed to enter.

[0092] Example 4

[0093] The embodiment of the application provides a method for determining EGR closed loop enabling time condition on the basis of examples 1-3, which specifically comprises:

[0094] As shown in the following table, the EGR closed loop enabling time condition is a flag bit, and the acquisition method is as follows: Figure 4 First, the working condition is judged:

[0095] 1) Condition 1.1 The time when the vehicle transmission system enters the parallel state from the series state does not exceed the preset time T0 (the series state and the parallel state can be understood from the patent CN202410210588.7 "torque distribution method and device, electronic equipment and storage medium"), and condition 1.2 The difference between the target EGR rate and the current minimum EGR rate r EGRRateMinFinal is not more than 0.01, the EGR closed loop enabling time condition is met;

[0096]

[0097] ​2) Condition 2.1 vehicle state is in series state, and condition 2.2 target EGR rate and current minimum EGR rate r EGRRateMinFinal Difference is not more than 0.01, and condition 2.3 engine torque fluctuation correction coefficient r TrqErr Exceeds preset value k1, and continuous meeting time exceeds T1, wherein k1 is 0.02 in the example, and then the EGR closed loop enabling time condition is not met. In the series working condition, if the engine is in the generating state, and the EGR rate is in the low case, and the engine torque fluctuation is large, the EGR enabling condition needs to be exited.

[0098] 3) In other cases, the EGR closed loop enabling time condition meets the state maintenance of the last state, and the default state is that the EGR closed loop enabling time condition is met.

[0099] Wherein the engine torque fluctuation correction coefficient r TrqErr is obtained by determining the difference between the actual EGR rate original value and the filtered value.

[0100] M TrqErrFilter (N) = K TrqErr × [M TrqErr (N) - M TrqErrFilter (N-1)] + M TrqErrFilter (N-1)

[0101] Wherein, M TrqErr is the difference between the engine requested fire path torque and the actual fire path torque (referred to as torque difference), M TrqErr (N) is the torque difference of the Nth sampling period, M TrqErrFilter is the first-order low-pass filtered torque difference, M TrqErrFilter (N) is the filtered torque difference of the Nth sampling period, M TrqErrFilter (N-1) is the filtered torque difference of the N-1th sampling period, N = 1, 2, 3…, M TrqErrFilter (0) is equal to the torque difference M TrqErr (0) at the 0th sampling period, which occurs at the time of vehicle power-on, and the default value is 0; the sampling period interval Δt is 10 ms in the example. K TrqErr is a coefficient: (the number of cylinders of the engine in the example is 4, k TrqErr is calibrated at 1000 rpm, The purpose of such setting is to normalize, without special calibration at different cylinder numbers and speeds, only k TrqErr of 4-cylinder engine and 1000 rpm speed needs to be calibrated, thereby reducing calibration test work), wherein m is the number of engine cylinders, n is the engine speed, k TrqErr is the torque difference filtering coefficient, which is 0.08 in the example. The filtered value of the difference between the engine requested fire path torque and the actual fire path torque MTrqErrFilter . wherein

[0102] The initial value of T0 is 0.15s in this example, but within the time when T0 time has not ended, it is assumed that there is still T0' time left at this time (T0' must be no more than T0), then T0' time is optimized to get new T01'. If the following conditions occur;

[0103] T01'=max{T0'x[1+f(Cnt LowKnock )+f(Cnt MediumKnock )+f(Cnt HighKnock )]x(1+r T0 ),0}

[0104] That is, if knock occurs in the process of meeting the EGR closed loop enabling time condition, then it is corrected according to different knock intensities (low intensity level, medium intensity level and high intensity level, which can be seen in patent CN202010608134.7 "A method and system for learning the octane number of oil") and the number of accumulations Cnt LowKnock , Cnt MediumKnock , Cnt HighKnock respectively. r T0 is the time T0 self-learning correction coefficient, its default value is 0, and can be saved after the vehicle is powered off.

[0105] The determination of f(Cnt LowKnock ), f(Cnt MediumKnock ), f(Cnt HighKnock ) is based on reducing the risk of knock and avoiding damage to the engine. Based on this, the specific calibration values in this example are as follows:

[0106] Cnt LowKnock ]]> 0 3 5 7 12 15 f(Cnt LowKnock )]]> 0 0.01 0.03 0.05 0.08 0.01

[0107] Cnt MediumKnock ]] 0 3 5 7 12 15 f(Cnt MediumKnock )]]> 0 0.05 0.08 0.1 0.15 0.18

[0108] Cnt HighKnock ]]> 0 1 3 7 10 12 f(Cnt HighKnock )]]> 0 0.1 0.2 0.4 0.8 1

[0109] In particular, once pre-ignition occurs, T01'=2s.

[0110] The update of T01' is updated at most once in the EGR closed loop enabling time condition judgment period (i.e. if the EGR closed loop enabling time condition is met to not met again, then it is a new judgment period).

[0111] The initial value of T0 is 0.15s in this example, but within the time when T0 time has not ended, it is assumed that there is still T0' time left at this time (T0' must be no more than T0), then T0' time is optimized to get new T01'. If the following conditions occur;

[0112]

[0113] wherein is the engine torque fluctuation correction coefficient r TrqErr is the accumulated value, and the starting time of accumulation is: 2.1) the vehicle state is in series state, and 2.2) the difference between the target EGR rate and the current minimum EGR rate r EGRRateMinFinal is not more than 0.01.r TrqErr0 is the engine torque fluctuation correction coefficient r TrqErr

[0114] is the T1 correction coefficient obtained based on .

[0115]

[0116] wherein r T1 is the self-learning coefficient of time T1, and the default value is 0, and can be saved after the vehicle is powered off.

[0117] Embodiment 5

[0118] On the basis of embodiments 1-4, the present application provides a learning updating method of the time T0 learning value r T0 and the time T1 learning value r T1 , specifically comprising:

[0119] 1. The learning of the time T0 learning value r T0 is as follows:

[0120] 2. If T01'-T0' is greater than a preset value C1 (0.1s in this example, which indicates that the time adjustment is too large due to knock or pre-ignition), and the continuous occurrence number CNT1 (the initial value is 0, and can be saved after the vehicle is powered off) exceeds a preset value (5 in this example), in order to further improve the guarantee of engine power output in parallel working condition, the T0 learning value r T0 is in the upward learning state, that is, r T1 needs to be increased.r T0 =r T0 (z)+0.02, wherein r T0 (z) is the time T0 learning value stored by the last learning. At the same time, CNT1 is cleared. The newly learned learning value is used when entering this kind of situation next time.

[0121] 3. If T01'-T0' is not greater than a preset value C2 (0.03 s in this example, indicating that knock or pre-ignition is not likely to occur), and the number of consecutive occurrences CNT2 (initial value 0, which can be saved after the vehicle is powered off) exceeds a preset value (5 in this example), the time T1 self-learning state is a downward learning state, i.e., r T1 needs to be reduced. T0 = r T0 (z)-0.01. The newly learned and stored learning value is used next time this condition is judged.

[0122] In other cases, r T0 remains unchanged.

[0123] The priority of the above three conditions is decreasing.

[0124] The time T1 learning value r T1 is learned as follows:

[0125] 1. If T1'-T11' is greater than a preset value C3 (0.5 s in this example, indicating that the time adjustment is too large due to knock or pre-ignition), and the number of consecutive occurrences CNT2 (initial value 0, which can be saved after the vehicle is powered off) exceeds a preset value (5 in this example), in order to further improve the engine torque output stability in series working conditions and thus improve the engine charging performance, the T1 learning value r T1 is in an upward learning state, i.e., r T1 needs to be increased (i.e., T1 needs to be reduced). r T1 = r T1 (z)+0.01, where r T1 (z) is the time T1 learning value learned and stored last time. At the same time, CNT2 is cleared. The newly learned and stored learning value is used next time this condition is judged.

[0126] 2. If T1'-T11' is not greater than a preset value C4 (0.03 s in this example, indicating that knock or pre-ignition is not likely to occur), and the number of consecutive occurrences CNT2 (initial value 0, which can be saved after the vehicle is powered off) exceeds a preset value (5 in this example), the time T1 self-learning state is a downward learning state, i.e., r T1 needs to be reduced (i.e., T1 is increased). r T1 = r T1 (z)-0.005. The newly learned and stored learning value is used next time this condition is judged.

[0127] 3. In other cases, r T1 remains unchanged.

[0128] The priority of the above three conditions is decreasing.

[0129] In summary, the above completes the description of the EGR closed-loop enabling algorithm, and after enabling, the EGR closed-loop control is performed, based on the target EGR rate and the actual EGR rate, the mixed valve and the EGR valve are controlled to act so that the actual EGR rate follows the target EGR rate.

[0130] Embodiment 6

[0131] As Figure 5 shown, the embodiment of the present application provides an EGR control system for improving engine power and safety, comprising:

[0132] The memory 21 is used to store executable computer programs.

[0133] The processor 22 is used to execute the executable computer programs stored in the memory, and realize the above-mentioned EGR control method for improving engine power and safety.

[0134] It should be understood that the size of the serial number of each step in the above embodiment does not mean the order of execution, and the execution order of each process should be determined according to its function and inherent logic, and should not constitute any limitation on the implementation process of the embodiment of the present application.

[0135] It should be understood that those skilled in the art can make improvements or changes according to the above description, and all these improvements and changes shall fall within the protection scope of the appended claims of the present application.

Claims

1. An EGR control method for improving engine power and safety, characterized in that, include: Based on the relationship between the time it takes for the vehicle's transmission system to transition from a series state to a parallel state and the preset time, and combined with the relationship between the difference between the target EGR rate and the minimum EGR rate and a certain threshold, it is determined whether the EGR closed-loop enable time condition is met; wherein, the preset time is updated in each driving cycle through a self-learning correction coefficient. If the EGR closed-loop enable time condition is met, then the relationship between the difference between the target EGR rate and the minimum EGR rate and the preset value is used to determine whether the EGR closed-loop enable minimum EGR rate condition is met. If the minimum EGR rate condition for EGR closed-loop enable is met, it is determined whether to enter EGR closed-loop enable. After enabling, EGR closed-loop control is performed. Based on the target EGR rate and the actual EGR rate, the mixing valve and EGR valve are controlled to make the actual EGR rate follow the target EGR rate.

2. The EGR control method for improving engine power and safety according to claim 1, characterized in that, Methods for determining whether the EGR closed-loop enable time condition is met include: If the time for transitioning from the series state to the parallel state does not exceed a preset time T0, and the difference between the target EGR rate and the minimum EGR rate does not exceed a certain threshold, then the EGR closed-loop enable time condition is met; otherwise: In series operation, if the difference between the target EGR rate and the minimum EGR rate does not exceed a certain threshold, and the engine torque fluctuation correction coefficient exceeds the preset value for a continuous period exceeding a certain threshold time T1, then the EGR closed-loop enable time condition is not met; otherwise: The state remains in the previous state when the EGR closed-loop enable time condition is met, and the default state is when the EGR closed-loop enable time condition is met.

3. The EGR control method for improving engine power and safety according to claim 2, characterized in that, The engine torque fluctuation correction coefficient is determined based on the difference between the engine's requested firing torque and the actual firing torque, as well as the torque difference after first-order low-pass filtering.

4. The EGR control method for improving engine power and safety according to claim 1, characterized in that, Methods for determining whether the minimum EGR rate condition for EGR closed-loop enable is met include: When the difference between the target EGR rate and the minimum EGR rate is greater than a preset value, the minimum EGR rate condition for enabling the EGR closed loop is met.

5. The EGR control method for improving engine power and safety according to claim 4, characterized in that, Methods for determining whether the minimum EGR rate condition for EGR closed-loop enable is met also include: If the difference between the target EGR rate and the minimum EGR rate is not greater than the preset value, and the absolute value of the difference between the target EGR rate and the actual EGR rate is not greater than the preset value, and the EGR closed-loop enable time condition is not met, then the minimum EGR rate condition for EGR closed-loop enable is not met. When the vehicle is powered on, it is in the default state, where the minimum EGR rate condition for EGR closed-loop enable is not met.

6. The EGR control method for improving engine power and safety according to claim 1, characterized in that, Methods for determining whether to enter the EGR closed-loop enable 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 is within the preset range; The EGR closed-loop state is allowed only if all of the above conditions are met; otherwise, the EGR closed-loop state is not allowed.

7. The EGR control method for improving engine power and safety according to claim 2, characterized in that, Optimization methods for the preset time T0 include: If, before time T0 has ended, there is still time T0' remaining, and T0' is no greater than T0, then time T0' is optimized to obtain a new T01'; the formula is as follows: in, , , These represent the cumulative number of detonation occurrences corresponding to low, medium, and high intensity levels, respectively. This is the self-learning correction coefficient for time T0, which has a default value of 0 and is saved after the vehicle is powered off. , , Obtained through calibration.

8. The EGR control method for improving engine power and safety according to claim 7, characterized in that, Methods for optimizing the threshold time T1 include: If, before time T1 has ended, there is still time T1' remaining, and T1' is no greater than T1, then time T1' is optimized to obtain a new T11'; the formula is as follows: in, Engine torque fluctuation correction coefficient The accumulated value starts accumulating when the vehicle is in a serial state and the difference between the target EGR rate and the minimum EGR rate does not exceed a certain threshold. The engine torque fluctuation correction coefficient at this initial moment. ; Based on The obtained T1 correction coefficient; The self-learning correction coefficient is for time T1.

9. The EGR control method for improving engine power and safety according to claim 8, characterized in that, Engine torque fluctuation correction coefficient The method for obtaining it is as follows: in, The difference between the requested firing torque and the actual firing torque of the engine. The torque difference is the result of a first-order low-pass filter.

10. The EGR control method for improving engine power and safety according to claim 9, characterized in that, The method for obtaining the filtered torque difference is as follows: in, The torque difference in the Nth sampling period. The filtered torque difference is the value in the Nth sampling period. The filtered torque difference is the value in the (N-1)th sampling period, where N = 1, 2, 3…; the sampling period interval is… , is a coefficient.

11. The EGR control method for improving engine power and safety according to claim 8, characterized in that, Self-learning correction coefficient Learning methods include: Learning methods: if If the value is greater than the preset value, and the number of consecutive occurrences (CNT1) exceeds the preset value (C1), then... Set to: ,in Set the learning value to the time T0 of the last learning and storage, and clear CNT1 to zero. if If the number of consecutive occurrences (CNT2) is not greater than the preset value, and the number of occurrences (CNT2) exceeds the preset value (C2), then... Set to: ; 12. The EGR control method for improving engine power and safety according to claim 8, characterized in that, Self-learning correction coefficient Learning methods include: Learning methods: if If the value is greater than the preset value C3, and the number of consecutive occurrences CNT2 exceeds the preset value, then... Set to: At the same time, CNT2 is cleared to zero; if If the number of consecutive occurrences (CNT2) is not greater than the preset value C4, then... Set to: .

13. An EGR control system for improving engine power and safety, characterized in that, include: Memory, used to store executable computer programs; A processor, when executing an executable computer program stored in a memory, implements the EGR control method for improving engine power and safety as described in any one of claims 1 to 9.

14. A computer-readable storage medium, characterized in that, The device contains a computer program that, when executed by a processor, implements the EGR control method for improving engine power and safety as described in any one of claims 1 to 12.

Images