EGR control method and system for improving dynamic property and safety of engine

Abstract

The invention discloses an EGR (Exhaust Gas Recirculation) control method and system for improving the dynamic property and safety of an engine, and the method comprises the following steps: judging whether an EGR closed-loop enabling time condition is met or not according to the relation between the time when a vehicle transmission system enters a parallel connection state from a series connection state and preset time in combination with a target EGR rate and a minimum EGR rate; wherein the preset time is updated in each driving cycle through the self-learning correction coefficient; if the EGR closed-loop enabling time condition is met, whether the EGR closed-loop enabling minimum EGR rate condition is met or not is judged according to the target EGR rate and the minimum EGR rate; and if the minimum EGR rate condition of EGR closed-loop enabling is met, whether EGR closed-loop enabling is carried out or not is judged, EGR closed-loop control is carried out after enabling, and based on the target EGR rate and the actual EGR rate, a mixing valve and an EGR valve are controlled to act so that the actual EGR rate can follow the target EGR rate. According to the method, the EGR closed-loop enabling condition is optimized, and the dynamic property and the control stability of the engine are improved.

Description

Technical Field

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

[0002] Exhaust Gas Recirculation (EGR) takes exhaust gas from the exhaust and enters the intake system. Studies have shown that the EGR system has certain advantages in improving emissions, reducing fuel consumption and improving anti-knock capabilities. The control of the mixing valve in the low-pressure EGR system is particularly important as it improves the effect of the EGR rate.

[0003] Due to the system hysteresis, when the EGR rate enters its minimum EGR rate area, it may cause the control actuator to oscillate, or even the EGR system to become unstable. Based on this, this patent is mainly aimed at optimizing the judgment method of EGR enabling conditions in hybrid vehicles, optimizing the EGR closed-loop enabling conditions, and thus improving the performance of engine power and control stability. Summary of the invention

[0004] The technical problem to be solved by the present invention 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 solution adopted by the present invention to solve its technical problem is:

[0006] The present invention 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, combined with the target EGR rate and the minimum EGR rate, it is determined whether the EGR closed-loop enabling time condition is met; wherein the preset time is updated in each driving cycle through the self-learning correction coefficient;

[0008] If the EGR closed-loop enabling time condition is met, whether the EGR closed-loop enabling minimum EGR rate condition is met is determined based on the target EGR rate and the minimum EGR rate;

[0009] If the minimum EGR rate condition for EGR closed-loop enabling is met, it is determined whether to enter EGR closed-loop enabling. 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 their actual EGR rate follow the target EGR rate.

[0010] Further, the method of the present invention for determining whether the EGR closed-loop enabling time condition is met includes:

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

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

[0013] The EGR closed-loop enabling time condition satisfaction state maintains the previous state, and the default state is that the EGR closed-loop enabling time condition is satisfied.

[0014] Furthermore, the engine torque fluctuation correction coefficient of the present invention is determined according to the torque difference between the engine's requested fire circuit torque and the actual fire circuit torque and the torque difference after first-order low-pass filtering.

[0015] Further, the method of the present invention 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 enables the minimum EGR rate condition to be met.

[0017] Furthermore, the method of determining whether the EGR closed-loop enabling minimum EGR rate condition is met in the present invention also includes:

[0018] When 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 enabling time condition is not met, the minimum EGR rate condition for EGR closed-loop enabling is not met;

[0019] The vehicle is in the default state when it is powered on, and the default state is that the minimum EGR rate condition for enabling the EGR closed loop is not met.

[0020] Furthermore, the method of determining whether to enter EGR closed loop enabling of the present invention includes:

[0021] There were no malfunctions related to the EGR system parts;

[0022] No fuel cut request occurs and the fuel cut recovery time exceeds the preset time;

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

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

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

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

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

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

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

[0030] Furthermore, the optimization method of the preset time T0 of the present invention includes:

[0031] In the time before T0 ends, assuming that there is still T0' time left and T0' is not greater than T0, then 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] Among them, Cnt LowKnock , Cnt MediumKnock , Cnt HighKnock are the cumulative number of knock occurrences corresponding to the knock intensities of low intensity level, medium intensity level and high intensity level, r T0 It is the self-learning correction coefficient of time T0, the default value is 0, and it is saved after the vehicle is powered off; f(Cnt LowKnock )、f(Cnt MediumKnock )、f(Cnt HighKnock ) is obtained through calibration.

[0034] Furthermore, the method for optimizing the threshold time T1 of the present invention includes:

[0035] In the time before T1 ends, assuming that there is still T1' time left and T1' is not greater than T1, then T1' time is optimized to obtain a new T11'; the formula is:

[0036]

[0037] in, is the engine torque fluctuation correction coefficient r TrqErr The accumulated value starts at the time when the vehicle is in series connection and the difference between the target EGR rate and the minimum EGR rate does not exceed a certain threshold; TrqErr0 is the engine torque fluctuation correction coefficient r at the starting time TrqErr ;

[0038] Based on The obtained T1 correction coefficient; r T1 It is the self-learning correction coefficient of time T1.

[0039] Furthermore, the engine torque fluctuation correction coefficient r of the present invention is TrqErr The method to obtain is:

[0040]

[0041] Among them, M TrqErr M is the difference between the engine's requested fire torque and the actual fire torque. TrqErrFilter is the torque difference after first-order low-pass filtering.

[0042] Furthermore, the method for obtaining the filtered torque difference of the present invention is:

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

[0044] Among them, M TrqErr (N) is the torque difference of the Nth sampling period, M TrqErrFilter (N) is the torque difference after filtering in the Nth sampling period, M TrqErrFilter (N-1) is the filtered torque difference of the N-1th sampling period, N = 1, 2, 3...; the sampling period interval Δt, K TrqErr is the coefficient.

[0045] Furthermore, the learning method of the self-learning correction coefficient of the present invention includes:

[0046] r T0 Learning method:

[0047] If T01'-T0' is greater than the preset value, and the number of consecutive occurrences CNT1 exceeds the preset value C1, r T0 Set to: r T0 =r T0 (z)+0.02, where r T0 (z) is the learning value of the last learning storage time T0, and CNT1 is cleared at the same time;

[0048] If T01'-T0' is not greater than the preset value, and the number of consecutive occurrences CNT2 exceeds the preset value C2, r T0 Set to: r T0 =r T0 (z) -0.01;

[0049] rT1 Learning method:

[0050] If T1'-T11' is greater than the preset value C3, and the number of consecutive occurrences CNT2 exceeds the preset value, r T1 Set to: r T1 =r T1 (z) + 0.01, and clear CNT2 at the same time;

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

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

[0053] a memory for storing executable computer programs;

[0054] The processor is used to implement the above-mentioned EGR control method for improving engine power and safety when executing the executable computer program stored in the memory.

[0055] The beneficial effects produced by the present invention are:

[0056] 1. The present 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 helping to improve the performance of engine power and control stability.

[0057] 2. The present invention determines whether the EGR closed-loop enabling time condition is met based on the relationship between the time when the vehicle transmission system enters the parallel state from the series state and the preset time, combined with the target EGR rate and the minimum EGR rate, and introduces the preset time updated by the self-learning correction coefficient in the judgment process, thereby improving the control accuracy and performance of each driving cycle.

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

[0059] 4. The present invention proposes a time T0 learning value r T0 and the self-learning coefficient r at time T1 T1 The setting method and the r T0 and r T1 Optimization learning is carried out to improve control accuracy and engine power. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which:

[0061] Figure 1 is a schematic diagram of the structure of a system with EGR according to an embodiment of the present invention;

[0062] 1. Air filter; 2. Mixing valve; 3. Compressor; 4. Throttle; 5. Engine; 6. Turbine; 7. Catalyst; 8. Particulate matter collector; 9. EGR cooler; 10. EGR valve; 11. Temperature sensor; 12. Pressure difference sensor.

[0063] Figure 2 is a flow chart of the overall method of an embodiment of the present invention;

[0064] Figure 3 : is a flow chart of the minimum EGR rate condition for enabling the EGR closed loop according to an embodiment of the present invention;

[0065] Figure 4 is a flow chart of EGR closed-loop enabling time conditions of an embodiment of the present invention;

[0066] Figure 5 It is a system block diagram of an embodiment of the present invention. DETAILED DESCRIPTION

[0067] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0068] Example 1

[0069] Before describing the contents of the embodiments of the present invention, a general description of the system structure with EGR is first given as a basis for the subsequent embodiments.

[0070] like Figure 1As shown in FIG. 1 , the structure of the system with EGR in the embodiment of the present invention includes: an air filter 1; a mixing valve 2 connected to the air filter, used to adjust the pressure at the outlet of the EGR valve 10, increase the pressure difference at both ends of the EGR valve 10, and extend two air flow paths from the mixing valve 2; a compressor 3 connected to one of the air flow paths of the mixing valve 2; a throttle 4 connected to the compressor 3; an engine 5 connected to the throttle 4, used to compress fresh air for supercharging; a turbine 6 connected to the engine 5, used to control the opening of the exhaust bypass valve; a catalyst 7 connected to the turbine 6; and a particle accelerator 7 connected to the catalyst 7. A particle collector 8; an EGR cooler 9 installed on another air flow path of the mixing valve 2, for receiving and cooling the exhaust gas output by the particle collector 8 to increase the exhaust gas flow rate; one end is connected to the EGR cooler 9, and the other end is connected to the EGR valve 10 of the mixing valve 2, for controlling the exhaust gas flow rate entering the cylinder; a temperature sensor 11 installed between the EGR valve 10 and the EGR cooler 9, for detecting the exhaust gas temperature entering the EGR valve 10; a pressure difference sensor 12 connected to the EGR valve 10, for detecting the pressure at the inlet and outlet of the EGR valve 10.

[0071] like Figure 2 As shown, the EGR control method for improving engine power and safety according to an embodiment of the present invention includes the following control process and judgment conditions:

[0072] Step 1: Determine whether the EGR closed-loop enabling time condition is met based on the relationship between the time when the vehicle transmission system enters the parallel state from the series state and the preset time, combined with the target EGR rate and the minimum EGR rate; wherein the preset time is updated in each driving cycle through the self-learning correction coefficient;

[0073] Step 2: If the EGR closed-loop enabling time condition is met, determine whether the EGR closed-loop enabling minimum EGR rate condition is met based on the target EGR rate and the minimum EGR rate;

[0074] Step 3: If the minimum EGR rate condition for EGR closed-loop enabling is met, determine whether to enter EGR closed-loop enabling. After enabling, perform EGR closed-loop control. Based on the target EGR rate and the actual EGR rate, control the mixing valve and EGR valve to make their actual EGR rate follow the target EGR rate.

[0075] The method of the embodiment of the present invention considers optimizing the EGR closed-loop enabling conditions from the perspective of power and torque stability in hybrid vehicles based on different transmission states (series state and parallel state), thereby further helping to improve the performance of engine power and control stability.

[0076] Example 2

[0077] like Figure 3As shown, based on Example 1, this embodiment of the present invention provides a method for determining the minimum EGR rate condition for enabling EGR closed loop, which specifically includes:

[0078] 1) When the difference between the target EGR rate and the minimum EGR rate (see the patent publication CN202211212260.6 "Minimum EGR rate adjustment method, device, equipment and storage medium") is greater than the preset value A, A = C1, C1 in this example is 0.02. Then the EGR closed loop enables the minimum EGR rate condition;

[0079] 2) Condition 2.1: When the target EGR rate is equal to the minimum EGR rate r EGRRateMinFinal The difference is not greater than the preset value B, B = C2, C2 in this example is 0.01; Condition 2.2, and the absolute value of the difference between the target EGR rate and the actual EGR rate is not greater than the preset value, in this example it is 0.1; Condition 2.3, and the EGR closed loop enabling time condition is not met. Then the minimum EGR rate condition for EGR closed loop enabling is not met;

[0080] 3) In other cases, the EGR closed loop enabling minimum EGR rate condition maintains the previous state. When the vehicle is powered on, it is the default state, and the default state is that the EGR closed loop enabling minimum EGR rate condition is not met.

[0081] Example 3

[0082] Based on Embodiments 1 and 2, the embodiment of the present invention provides a method for determining entering an EGR closed-loop state, which specifically includes:

[0083] 1) There are no related faults of EGR system parts;

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

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

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

[0087] 5) The intake air temperature is within the preset range. If the current state is that the EGR closed loop is not enabled, then the EGR closed loop state is entered, and the minimum intake air temperature must be no less than 10°C. If the current state is that the EGR closed loop is enabled, then the EGR system closed loop enabled state must be exited to ensure that the minimum intake air temperature is 7°C lower than the minimum intake air temperature. If the current state is that the EGR closed loop is not enabled, then the EGR closed loop state is entered, and the maximum intake air temperature must be no more than 60°C. If the current state is that the EGR closed loop is enabled, then the EGR system closed loop enabled state must be exited to ensure that the maximum intake air temperature is 65°C.

[0088] 6) The engine water temperature is within the preset range. If the current state is that the EGR closed loop is not enabled, then entering the EGR closed loop state, the water temperature must not be lower than the minimum of 60°C. If the current state is that the EGR closed loop is enabled, then exiting the EGR system closed loop enabled state requires the water temperature to be lower than the minimum of 55°C. If the current state is that the EGR closed loop is not enabled, then entering the EGR closed loop state requires the water temperature to not exceed the maximum of 115°C. If the current state is that the EGR closed loop is enabled, then exiting the EGR system closed loop enabled state requires the water temperature to exceed the maximum of 120°C.

[0089] 7) The atmospheric temperature is within the preset range. If the current state is that the EGR closed loop is not enabled, then entering the EGR closed loop state requires that the atmospheric temperature is not lower than the minimum atmospheric temperature of 5°C. If the current state is that the EGR closed loop is enabled, then exiting the EGR system closed loop enabled state requires that the atmospheric temperature is lower than the minimum atmospheric temperature of 3°C. If the current state is that the EGR closed loop is not enabled, then entering the EGR closed loop state requires that the atmospheric temperature does not exceed the maximum atmospheric temperature of 55°C. If the current state is that the EGR closed loop is enabled, then exiting the EGR system closed loop enabled state requires that the atmospheric temperature exceeds the maximum atmospheric temperature of 60°C.

[0090] 8) When the atmospheric pressure exceeds 66 kPa, the EGR closed loop enabling condition is allowed. When the atmospheric temperature is lower than 64 kPa, the EGR closed loop enabling condition needs to be exited.

[0091] The EGR closed-loop state is allowed only when the above conditions are met, otherwise entering the EGR closed-loop state is not allowed.

[0092] Example 4

[0093] The embodiment of the present invention provides a method for determining the EGR closed-loop enabling time condition based on the embodiments 1-3, which specifically includes:

[0094] like Figure 4 As shown, the EGR closed loop enabling time condition is a flag, and the method for obtaining it is as follows:

[0095] First, determine the working condition:

[0096] 1) Condition 1.1 The time for the vehicle transmission system to enter the parallel state from the series state does not exceed the preset time T0 (the understanding of the series state and the parallel state can be found in patent CN202410210588.7 "Torque distribution method and device, electronic device and storage medium"), and condition 1.2 The target EGR rate is equal to the current minimum EGR rate r EGRRateMinFinal The difference does not exceed 0.01, and the EGR closed-loop enabling time condition is met;

[0097] 2) Condition 2.1 The vehicle state is in series state, and condition 2.2 The target EGR rate is equal to the current minimum EGR rate r EGRRateMinFinal The difference does not exceed 0.01, and condition 2.3 engine torque fluctuation correction coefficient r TrqErr If the continuous satisfaction time exceeding the preset value k1 exceeds T1, where k1 in this example is 0.02, the EGR closed-loop enabling time condition is not met. In the series working condition, if the engine is in the power generation state and the engine torque fluctuates greatly when the EGR rate is very low, it is necessary to exit the EGR enabling condition.

[0098] 3) In other cases, the EGR closed-loop enabling time condition satisfaction state maintains the previous state, and the default state is that the EGR closed-loop enabling time condition is satisfied.

[0099] The engine torque fluctuation correction coefficient r TrqErr The acquisition method is determined based on the difference between the original value and the filtered value of the actual EGR rate.

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

[0101] Among them, M TrqErr M is the difference between the engine's requested torque and the actual torque (torque difference for short), TrqErr (N) is the torque difference of the Nth sampling period, M TrqErrFilter is the torque difference after first-order low-pass filtering, M TrqErrFilter (N) is the torque difference after filtering in 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 at the 0th sampling period TrqErr (0), which occurs when the vehicle is powered on, and the default value is 0; the sampling period interval Δt in this example is 10ms. K TrqErr is the coefficient: (The number of engine cylinders in this example is 4, k TrqErr The calibrated speed is 1000rpm. The purpose of this setting is to normalize the process. Under different cylinder numbers and speeds, no special calibration is required. Only the 4-cylinder engine and the speed of 1000rpm k TrqErr , thereby reducing the calibration test work), where m is the number of engine cylinders, n is the engine speed, k TrqErr is the torque difference filter coefficient, which is 0.08 in this example. The above obtains the difference filter value M between the engine request fire circuit torque and the actual fire circuit torqueTrqErrFilter .in

[0102] The initial value of T0 in this example is 0.15s. However, before T0 ends, assuming that there is still T0' time left (T0' is definitely not greater than T0), then T0' time is optimized to obtain a new T01' if the following situation occurs;

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

[0104] That is, if the engine knocks during the EGR closed-loop enabling time condition is met, the knock intensity (low intensity level, medium intensity level and high intensity level, see patent CN202010608134.7 "A method and system for self-learning of oil octane number") and the accumulated number Cnt are respectively LowKnock , Cnt MediumKnock , Cnt HighKnock Make corrections. T0 It is the self-learning correction coefficient of time T0, its default value is 0, and it can be saved after the vehicle is powered off.

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

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

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

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

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

[0110] T01' is updated at most once within the EGR closed-loop enabling time condition judgment cycle (ie, if the EGR closed-loop enabling time condition is satisfied and then becomes unsatisfied and then enters satisfaction again, it is a new judgment cycle).

[0111] The initial value of T1 in this example is 0.1s. However, before T1 ends, assuming that there is still T1' time left (T1' is definitely not greater than T1), then T1' time is optimized to obtain a new T11' if the following conditions occur:

[0112]

[0113] in is the engine torque fluctuation correction coefficient r TrqErr The accumulated value starts at: 2.1) the vehicle is in series connection, and 2.2) the target EGR rate is equal to the current minimum EGR rate r EGRRateMinFinal The difference does not exceed 0.01. TrqErr0 is the engine torque fluctuation correction coefficient r at the starting time TrqErr

[0114] Based on Obtained T1 correction factor.

[0115]

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

[0117] Example 5

[0118] Based on the embodiments 1-4, the embodiment of the present invention provides a time T0 learning value r T0 and time T1 learning value r T1 The learning update method includes:

[0119] 1. Time T0 learning value r T0 The learning situation is as follows:

[0120] 2. If T01'-T0' is greater than the preset value C1 (0.1s in this example), it means that the time adjustment caused by knock or pre-ignition is too large, and the number of consecutive occurrences CNT1 (initial value is 0, which can be saved after the vehicle is powered off) exceeds the preset value (5 in this example), in order to further improve the engine power output under parallel working conditions, the T0 learning value r T0 The self-learning state is the upward learning state 1, that is, r T1 Need to increase. T0 =r T0 (z)+0.02, where r T0 (z) is the learning value of the last learning and storage time T0. At the same time, CNT1 is cleared. The newly learned and stored learning value is used when entering this situation judgment next time.

[0121] 3. If T01'-T0' is not greater than the preset value C2 (0.03s in this example, indicating that knock or pre-ignition is not likely to occur), and the number of consecutive occurrences CNT2 (initial value is 0, which can be saved after the vehicle is powered off) exceeds the preset value (5 in this example), then the time T1 self-learning state is set to downward learning state 1, that is, r T1 Need to be lowered. T0 =r T0 (z) -0.01. The newly learned and stored learning value is used the next time the same situation is judged.

[0122] In other cases, T0 Remain unchanged.

[0123] The priorities of the above three conditions are getting lower and lower.

[0124] Time T1 learning value r T1 The learning situation is as follows:

[0125] 1. If T1'-T11' is greater than the preset value C3 (0.5s in this example), it means that the time adjustment caused by knock or pre-ignition is too large, and the number of consecutive occurrences CNT2 (initial value is 0, which can be saved after the vehicle is powered off) exceeds the preset value (5 in this example), in order to further improve the stability of engine torque output under series working conditions and thus improve the charging performance of the engine, the T1 learning value r T1 The self-learning state is the upward learning state 1, that is, r T1 Need to be increased (ie T1 needs to be decreased). T1 =r T1 (z)+0.01, where r T1 (z) is the learning value of the last learning and storage time T1. At the same time, CNT2 is cleared. The newly learned and stored learning value is used when entering this situation judgment next time.

[0126] 2. If T1'-T11' is not greater than the preset value C4 (0.03s in this example, indicating that knock or pre-ignition is not likely to occur), and the number of consecutive occurrences CNT2 (initial value is 0, which can be saved after the vehicle is powered off) exceeds the preset value (5 in this example), then the time T1 self-learning state is set to downward learning state 1, that is, r T1 Need to be reduced (ie T1 increased). T1 =r T1 (z) -0.005. The newly learned and stored learning value is used the next time the judgment is made in this situation.

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

[0128] The priorities of the above three conditions are getting lower and lower.

[0129] In summary, the above completes the entire description of the EGR closed-loop enabling algorithm. After enabling, 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 make the actual EGR rate follow the target EGR rate.

[0130] Example 6

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

[0132] A memory 21, used for storing executable computer programs;

[0133] The processor 22 is used to implement the above-mentioned EGR control method for improving engine power and safety when executing the executable computer program stored in the memory.

[0134] It should be understood that the size of the serial numbers of the steps in the above embodiments does not mean 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 the present application.

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

Claims

1. An EGR control method for improving engine power and safety, characterized in that: include: According to the relationship between the time when the vehicle transmission system enters the parallel state from the series state and the preset time, combined with the target EGR rate and the minimum EGR rate, it is determined whether the EGR closed-loop enabling time condition is met; wherein the preset time is updated in each driving cycle through the self-learning correction coefficient; If the EGR closed-loop enabling time condition is met, whether the EGR closed-loop enabling minimum EGR rate condition is met is determined based on the target EGR rate and the minimum EGR rate; If the minimum EGR rate condition for EGR closed-loop enabling is met, it is determined whether to enter EGR closed-loop enabling. 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 their 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: The method for determining whether the EGR closed-loop enabling time condition is met includes: If the time from the series state to the parallel state does not exceed the preset time T0, and the difference between the target EGR rate and the minimum EGR rate does not exceed a certain threshold, the EGR closed-loop enabling time condition is met; otherwise: In the series state, if the target EGR rate and the minimum EGR rate exceed a certain threshold, and the engine torque fluctuation correction coefficient exceeds the preset value for a continuous period of time exceeding a certain threshold time T1, the EGR closed-loop enabling time condition is not met; otherwise: The EGR closed-loop enabling time condition satisfaction state maintains the previous state, and the default state is that the EGR closed-loop enabling time condition is satisfied.

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 according to the torque difference between the engine's requested fire path torque and the actual fire path torque and 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: The method for determining whether the minimum EGR rate condition for enabling EGR closed loop is met includes: When the difference between the target EGR rate and the minimum EGR rate is greater than a preset value, the EGR closed loop enables the minimum EGR rate condition to be met.

5. The EGR control method for improving engine power and safety according to claim 4, characterized in that: The method for determining whether the EGR closed-loop enabling minimum EGR rate condition is met also includes: When 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 enabling time condition is not met, the minimum EGR rate condition for EGR closed-loop enabling is not met; The vehicle is in the default state when it is powered on, and the default state is that the minimum EGR rate condition for enabling the EGR closed loop 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 EGR closed loop enable include: There were no malfunctions related to the EGR system parts; No fuel cut request occurs and the fuel cut recovery time exceeds the preset time; The minimum EGR rate condition for EGR closed loop is met; The engine speed is within the preset speed range; The intake air temperature is within the preset range; The engine water temperature is within the preset range; The atmospheric temperature is within the preset range; The atmospheric pressure is within the preset range; The EGR closed-loop state is allowed only when the above conditions are met, otherwise entering 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: The optimization method of the preset time T0 includes: In the time before T0 ends, assuming that there is still T0' time left and T0' is not greater than T0, then T0' time is optimized to obtain a new T01'; the formula is: T01'=max{T0'×[1+f(Cnt LowKnock )+f(Cnt MediumKnock )+f(Cnt HighKnock )]×(1+r T0 ),0} Among them, Cnt LowKnock , Cnt MediumKnock , Cnt HighKnock are the cumulative number of knock occurrences corresponding to the knock intensities of low intensity level, medium intensity level and high intensity level, r T0 It is the self-learning correction coefficient of time T0, the default value is 0, and it is saved after the vehicle is powered off; f(Cnt LowKnock )、f(Cnt MediumKnock )、f(Cnt HighKnock ) is 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: In the time before T1 ends, assuming that there is still T1' time left and T1' is not greater than T1, then T1' time is optimized to obtain a new T11'; the formula is: in, is the engine torque fluctuation correction coefficient r TrqErr The accumulated value starts at the time when the vehicle is in series connection and the difference between the target EGR rate and the minimum EGR rate does not exceed a certain threshold; TrqErr0 is the engine torque fluctuation correction coefficient r at the starting time TrqErr ; Based on The obtained T1 correction coefficient; r T1 It is the self-learning correction coefficient of time T1.

9. The EGR control method for improving engine power and safety according to claim 8, characterized in that: Engine torque fluctuation correction factor r TrqErr The method to obtain is: Among them, M TrqErr M is the difference between the engine's requested fire torque and the actual fire torque. TrqErrFilter is the torque difference after first-order low-pass filtering.

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: M TrqErrFilter (N)=K TrqErr ×[M TrqErr (N)-M TrqErrFilter (N-1)]+M TrqErrFilter (N-1) Among them, M TrqErr (N) is the torque difference of the Nth sampling period, M TrqErrFilter (N) is the torque difference after filtering in the Nth sampling period, M TrqErrFilter (N-1) is the filtered torque difference of the N-1th sampling period, N = 1, 2, 3...; the sampling period interval Δt, K TrqErr is the coefficient.

11. The EGR control method for improving engine power and safety according to claim 8, characterized in that: Self-learning correction factor r T0 The learning methods include: r T0 Learning method: If T01'-T0' is greater than the preset value, and the number of consecutive occurrences CNT1 exceeds the preset value C1, r T0 Set to: r T0 =r T0 (z)+0.02, where r T0 (z) is the learning value of the last learning storage time T0, and CNT1 is cleared at the same time; If T01'-T0' is not greater than the preset value, and the number of consecutive occurrences CNT2 exceeds the preset value C2, r T0 Set to: r T0 =r T0 (z)-0.

01.

12. The EGR control method for improving engine power and safety according to claim 8, characterized in that: Self-learning correction factor r T1 The learning methods include: r T1 Learning method: If T1'-T11' is greater than the preset value C3, and the number of consecutive occurrences CNT2 exceeds the preset value, r T1 Set to: r T1 =r T1 (z) + 0.01, and clear CNT2 at the same time; If T1'-T11' is not greater than the preset value C4, and the number of consecutive occurrences CNT2 exceeds the preset value, r T1 Set to: r T1 =r T1 (z)-0.

005.

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

14. A computer-readable storage medium, characterized in that: A computer program is stored, which is used to implement the EGR control method for improving engine power and safety as described in any one of claims 1 to 12 when executed by a processor.

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