Control method and apparatus for EGR system of engine, storage medium, and vehicle

Abstract

A control method and apparatus for an EGR system (20) of an engine (10), a storage medium, and a vehicle. The control method for the EGR system (20) of the engine (10) comprises: acquiring a measured knock retard angle and a target knock retard angle of the engine (10), and calculating a knock retard angle deviation between the target knock retard angle and the measured knock retard angle; determining an open-loop correction coefficient of knock intensity on the basis of the knock retard angle deviation; correcting the current target EGR rate on the basis of the open-loop correction coefficient to obtain a corrected target EGR rate; and adjusting an opening degree of an EGR valve (21) of the EGR system (20) on the basis of the corrected target EGR rate.

Description

Control method and device for EGR system of engine, storage medium and vehicle

[0001] Cross-reference to related applications

[0002] The present application claims priority to and the benefit of the filing date of Chinese Patent Application No. 202410968283.2, filed on July 18, 2024, and is hereby incorporated by reference in its entirety. TECHNICAL FIELD

[0003] The present application relates to the technical field of engines, and specifically relates to a control method and device for an EGR system of an engine, a storage medium and a vehicle. BACKGROUND

[0004] In actual application, on the one hand, due to the pollution of exhaust gas to the EGR cooler or system pipeline, the system pipeline is seriously blocked or the EGR cooler is eroded, so that the actual EGR flow into the engine cylinder is relatively small compared to the target EGR flow, the actual EGR rate is small, and then strong knock of the engine is caused. On the other hand, due to the damage of the EGR system pipeline or the EGR cooler caused by the EGR hardware problem, the actual EGR flow into the engine cylinder is relatively small compared to the target EGR flow, the actual EGR rate is small, and then strong knock of the engine is caused.

[0005] In related technologies, in response to the knock of the engine, the ignition angle is delayed according to the knock intensity signal to reduce the knock intensity. However, a large number of knock delay angles will affect the combustion stability of the engine, further induce stronger knock, and then cause damage to the engine. SUMMARY

[0006] One of the purposes of the present application is to provide a control method and device for an EGR system of an engine, a storage medium and a vehicle to solve the problem in related technologies that the ignition angle is delayed according to the knock intensity signal, a large number of knock delay angles will affect the combustion stability of the engine, further induce stronger knock, and then cause damage to the engine. In addition, the strong knock of the engine caused by the damage of the EGR system pipeline or the EGR cooler due to the EGR hardware problem.

[0007] In order to achieve the above-mentioned purposes, the technical solutions adopted by the present application are as follows:

[0008] The application discloses a control method of an EGR system of an engine, comprising: obtaining a measured knock back angle amount and a target knock back angle amount of the engine, and calculating a knock back angle deviation amount of the target knock back angle amount and the measured knock back angle amount; determining an open-loop correction coefficient of knock intensity according to the knock back angle deviation amount; correcting a current target EGR rate according to the open-loop correction coefficient to obtain a corrected target EGR rate; and adjusting an opening degree of an EGR valve body of the EGR system according to the corrected target EGR rate.

[0009] According to the above technical means, during the operation of the engine, the measured knock back angle amount and the target knock back angle amount of the engine are obtained, and the knock back angle deviation amount is determined. The knock back angle deviation amount can feedback the knock intensity of the engine. Then, the open-loop correction coefficient is determined according to the knock back angle deviation amount. The current target EGR rate is corrected by using the open-loop correction coefficient, so as to compensate the actual EGR rate of the EGR system, thereby reducing the knock intensity of the engine, and enabling the engine to operate in a safe working state and effectively reducing the damage of abnormal knock to the engine in the open state of the EGR system.

[0010] Further, the step of determining the open-loop correction coefficient of knock intensity according to the knock back angle deviation amount comprises: determining the open-loop correction coefficient of knock intensity as 1 in the case that the knock back angle deviation amount is less than or equal to 0; obtaining the speed and the target load of the engine in the case that the knock back angle deviation amount is greater than 0; determining an initial open-loop correction coefficient of the current sampling time according to the speed, the target load and the measured knock back angle amount of the engine; and filtering the initial open-loop correction coefficient of the current sampling time to obtain the open-loop correction coefficient of knock intensity.

[0011] According to the above technical means, in the case that the knock back angle deviation amount is less than or equal to 0, that is, the target knock back angle amount is less than or equal to the measured knock back angle amount, in this case, it is indicated that the measured knock back angle amount is greater than the target knock back angle amount, and the probability of knock is low, then the open-loop correction coefficient of knock intensity is determined as 1, and the current target EGR rate can be maintained without correction. In the case that the knock back angle deviation amount is greater than 0, that is, the target knock back angle amount is greater than the measured knock back angle amount, then the probability of knock is high. In order to reduce the probability of knock, the current target EGR rate is corrected. Specifically, the initial open-loop correction coefficient of the current sampling time is determined according to the speed, the target load and the measured knock back angle amount of the engine, so that the measured knock back angle amount can quickly reach the target knock back angle amount. However, since the frequency of determining the initial open-loop correction coefficient of the current sampling time is fast, the fluctuation range of the determined coefficient is large. In order to reduce the disturbance, the initial open-loop correction coefficient of the current sampling time is filtered to obtain the open-loop correction coefficient of knock intensity of the current sampling time.

[0012] Further, the formula for determining the initial open-loop correction coefficient at the current sampling moment is: Openloop rc = Map1 (Imep s, Knockrtd avg), wherein Openloop rc is the initial open-loop correction coefficient, Imep s is the target load, and Knockrtd avg is the measured knock retardation amount.

[0013] According to the above technical means, the open-loop correction coefficient of the knock intensity is determined in a lookup table manner according to the obtained target load Imep s of the engine and the measured knock retardation amount Knockrtd avg. In this way, the open-loop correction coefficient of the knock intensity can be quickly determined according to the current operating condition, so as to quickly correct the current target EGR rate.

[0014] Further, the step of filtering the initial open-loop correction coefficient at the current sampling moment to obtain the open-loop correction coefficient of the knock intensity comprises: in the case that the open-loop correction coefficient of the knock intensity at the previous sampling moment is greater than the initial open-loop correction coefficient at the current sampling moment, calculating the difference between the open-loop correction coefficient of the knock intensity at the previous sampling moment and a preset decreasing step; selecting the maximum value between the calculated difference and the initial open-loop correction coefficient at the current sampling moment as the open-loop correction coefficient of the knock intensity at the current sampling moment.

[0015] According to the above technical means, in the case that the open-loop correction coefficient of the knock intensity at the previous sampling moment is greater than the initial open-loop correction coefficient at the current sampling moment, the open-loop correction coefficient is positively filtered to reduce the fluctuation amplitude of the open-loop correction coefficient.

[0016] Further, the step of filtering the initial open-loop correction coefficient at the current sampling moment to obtain the open-loop correction coefficient of the knock intensity comprises: in the case that the open-loop correction coefficient of the knock intensity at the previous sampling moment is less than the initial open-loop correction coefficient at the current sampling moment, calculating the sum of the open-loop correction coefficient of the knock intensity at the previous sampling moment and a preset increasing step; selecting the minimum value between the calculated sum and the initial open-loop correction coefficient at the current sampling moment as the open-loop correction coefficient of the knock intensity at the current sampling moment.

[0017] According to the above technical means, in the case that the open-loop correction coefficient of the knock intensity at the previous sampling moment is less than the initial open-loop correction coefficient at the current sampling moment, the open-loop correction coefficient is negatively filtered to reduce the fluctuation amplitude of the open-loop correction coefficient.

[0018] Further, the step of filtering the initial open-loop correction coefficient of the knock intensity at the current sampling time to obtain the open-loop correction coefficient of the knock intensity comprises: in the case that the open-loop correction coefficient of the knock intensity at the previous sampling time is equal to the initial open-loop correction coefficient at the current sampling time, taking the initial open-loop correction coefficient at the current sampling time as the open-loop correction coefficient of the knock intensity at the current sampling time.

[0019] According to the above technical means, in the case that the open-loop correction coefficient of the knock intensity at the previous sampling time is equal to the initial open-loop correction coefficient at the current sampling time, the initial filtering is performed on the open-loop correction coefficient to reduce the fluctuation range of the open-loop correction coefficient.

[0020] Further, the step of correcting the current target EGR rate according to the open-loop correction coefficient to obtain the corrected target EGR rate comprises: obtaining an EGR valve operating condition of the EGR system; and determining a closed-loop correction coefficient of the knock intensity according to the knock back angle deviation and the EGR valve operating condition. The current target EGR rate is corrected according to the open-loop correction coefficient and the closed-loop correction coefficient to obtain the corrected target EGR rate.

[0021] According to the above technical means, in the case that the EGR valve operating condition meets the set condition, the closed-loop correction coefficient of the knock intensity is determined according to the knock back angle deviation and the EGR valve operating condition, and the correction accuracy of the current target EGR rate is further improved by using the closed-loop correction coefficient. Further, the open-loop correction coefficient is used to control the measured knock back angle Knockrtd_avg to be close to the target knock back angle. Then, the correction accuracy is improved by using the closed-loop correction coefficient, so that the EGR valve opening of the EGR system is adjusted according to the corrected target EGR rate, and the actual EGR rate of the EGR system is compensated to reduce the knock intensity of the engine, so that the engine can operate in a safe working state and effectively reduce the damage of abnormal knock to the engine in the open state of the EGR system.

[0022] Further, the formula for obtaining the corrected target EGR rate is: EGR_Corr=EGR_S*(Openloop_r+Closeloop_r), wherein EGR_Corr is the corrected target EGR rate, EGR_S is the current target EGR rate, Openloop_r is the open-loop correction coefficient of the knock intensity, and Closeloop_r is the closed-loop correction coefficient of the knock intensity.

[0023] According to the above technical means, the sum of the determined open-loop correction system and the closed-loop correction coefficient is multiplied by the current target EGR rate EGR_S, and then the corrected target EGR rate is obtained. In this way, through iterative cyclic correction of the target EGR rate, the control of the knock intensity of the engine is realized, so that the knock intensity of the engine can be within the design range of the engine, and the damage caused by knock to the engine is reduced.

[0024] Further, the formula for determining the closed-loop correction coefficient of the knock intensity is:

[0025] Wherein, closeloop_r is the closed-loop correction coefficient; B_egri is the state value of the EGR valve operating condition monitoring; ɑ i is the value of the closed-loop correction integral factor, and ɑ i is assigned according to the state value of the knockback state monitoring; n is the sampling time sequence number, n = 1, 2, 3…; Mɑx r is the upper limit value of the closed-loop correction integral value, and Min r is the lower limit value of the closed-loop correction integral value.

[0026] According to the above technical means, the closed-loop correction coefficient closeloop_r is determined according to the state value of the EGR valve operating condition monitoring. As shown in the above formula, in the case that all the EGR valve operating conditions meet the set conditions, the state value B_egri of the EGR valve operating condition monitoring is 1, in which case, the closed-loop correction integral value is calculated, and the closed-loop correction coefficient closeloop_r is determined by comparing the calculated closed-loop correction integral value with Mɑx r and Min r . In the case that the EGR valve operating conditions do not meet the set conditions, the state value B_egri is 0, and the closed-loop correction coefficient closeloop_r is 0.

[0027] Further, the determination method of the state value of the EGR valve operating condition monitoring includes: monitoring the EGR valve operating condition, and the EGR valve operating condition includes: vehicle speed judgment condition, catalyst heating judgment condition, engine water temperature condition, lambda closed-loop condition, air-fuel ratio enrichment condition, starting judgment condition, engine intake temperature condition, EGR intake temperature condition and target EGR opening condition; in the case that all the EGR valve operating conditions meet the set conditions, the state value B_egri of the EGR valve operating condition monitoring is 1, otherwise the state value B_egri is 0.

[0028] According to the above technical means, when all the judgment conditions of the EGR valve operating condition monitoring module are monitored and meet, the state value B_egri of the EGR valve operating condition monitoring is 1, otherwise the state value B_egri is 0. And when the state value B_egri is 1, the closed loop correction coefficient closeloop_r is determined. When the state value B_egri is 0, the closed loop correction coefficient closeloop_r is 0, that is, no closed loop correction is needed.

[0029] Further, according to the state value of the knockback angle state monitoring, ɑ i The step of assigning includes: when the measured knockback angle is greater than the target knockback angle, the knock intensity judgment condition outputs 1, otherwise 0; when the actual EGR rate is greater than the target EGR rate threshold, the EGR rate judgment condition outputs 1, otherwise 0; when the knock intensity judgment condition, the EGR rate judgment condition and the engine misfire diagnosis output are all 1, the state value B_egrknck of the knockback angle state monitoring outputs 1, otherwise 0; when B_egrknck outputs 1, ɑ i equals the negative integral factor INT_down; when B_egrknck outputs 0, ɑ i equals the positive integral factor INT_up.

[0030] According to the above technical means, according to the state value of the knockback angle state monitoring module output, ɑ i is assigned. Specifically, the conditions monitored by the knockback angle state monitoring module include: knock intensity judgment condition, EGR rate judgment condition and engine misfire judgment condition. When the knock intensity judgment condition, the EGR rate judgment condition and the engine misfire judgment condition output are all 1, the state value B_egrknck of the knockback angle state monitoring outputs 1, otherwise 0. When B_egrknck outputs 1, ɑ i equals the negative integral factor INT_down; when B_egrknck outputs 0, ɑ i equals the positive integral factor INT_up. In this way, according to the state value of the knockback angle state monitoring output, it is determined whether ɑ i is positive integral correction or negative integral correction, so that the measured knockback angle is closer to the target knockback angle.

[0031] Further, the step of obtaining the measured knockback angle of the engine includes: obtaining the knockback angle of a plurality of cylinders of the engine at the current sampling time. Calculate the average of the plurality of knockback angles as the measured knockback angle of the engine.

[0032] According to the above technical means, by detecting a plurality of knock recession amounts, the average value of the plurality of knock recession amounts is calculated as the measured knock recession amount, so as to avoid that the fluctuation of the single detected knock recession amount is large, the average value is used to improve the stability of the measured knock recession amount, and then the stability of the calculated knock recession deviation amount is improved, so as to improve the accuracy of the subsequently determined open-loop correction coefficient.

[0033] A control device of an EGR system of an engine, comprising a knock monitoring module, configured to obtain a measured knock recession amount and a target knock recession amount of the engine, and calculate a knock recession deviation amount of the target knock recession amount and the measured knock recession amount; an EGR open-loop correction module, configured to determine an open-loop correction coefficient of knock intensity according to the knock recession deviation amount, and correct a current target EGR rate according to the open-loop correction coefficient to obtain a corrected target EGR rate; and an EGR valve control module, configured to adjust the opening degree of an EGR valve body of the EGR system according to the corrected target EGR rate.

[0034] Further, the control device further comprises an EGR closed-loop correction module, configured to determine a closed-loop correction coefficient of knock intensity according to the knock recession deviation amount and an EGR valve operating condition.

[0035] Further, the EGR closed-loop correction module comprises an EGR valve operating condition monitoring module, configured to monitor whether the EGR valve operating condition meets a set condition and output a state value; a knock recession state monitoring module, configured to output a state value monitoring the knock recession state; and a closed-loop correction integral value calculation module, configured to calculate the closed-loop correction integral value of the closed-loop correction integral factor at n sampling time according to the formula ɑ i wherein, ɑ is the value of the closed-loop correction integral factor, and n=1, 2, 3, ….

[0036] A control device of an EGR system of an engine, comprising a processor and a memory storing program instructions, the processor is configured to execute the control method of the EGR system of the engine according to any one of the above embodiments when running the program instructions.

[0037] A computer readable storage medium, storing program instructions, the program instructions are used to make the computer execute the control method of the EGR system of the engine according to any one of the above embodiments when running.

[0038] A vehicle, comprising the control device of the EGR system of the engine according to any one of the above embodiments.

[0039] The beneficial effects of the present application are:

[0040] The present application determines the knock intensity of the engine by detecting the knock recession amount of the engine. According to the knock recession deviation amount between the target knock recession amount and the measured knock recession amount, the open-loop correction coefficient of the current target EGR rate under different working conditions is determined and corrected to obtain the corrected target EGR rate. According to the corrected target EGR rate, the opening degree of the EGR valve is controlled to compensate the actual EGR rate under different working conditions, so as to control the knock intensity of the engine, so that the engine can run in a safe working state, and effectively reduce the damage of abnormal knock in the EGR open state to the engine. BRIEF DESCRIPTION OF DRAWINGS

[0041] Fig. 1 is a structural schematic diagram of an EGR system for an engine according to an embodiment of the present application;

[0042] Fig. 2 is a flowchart of a control method of an EGR system for an engine according to an embodiment of the present application;

[0043] Fig. 3 is a flowchart of a control method of an EGR system for an engine according to another embodiment of the present application;

[0044] Fig. 4 is a flowchart of a control method of an EGR system for an engine according to still another embodiment of the present application;

[0045] Fig. 5 is a block diagram of a control device of an EGR system for an engine according to an embodiment of the present application;

[0046] Fig. 6 is a block diagram of a control device of an EGR system for an engine according to another embodiment of the present application;

[0047] Fig. 7 is a block diagram of an EGR valve operating condition monitoring module according to an embodiment of the present application;

[0048] Fig. 8 is a block diagram of a knock recession state monitoring module according to an embodiment of the present application;

[0049] Fig. 9 is a block diagram of a control device of an EGR system for an engine according to still another embodiment of the present application.

[0050] Reference signs: 10 engine; 11 intake pipe; 12 exhaust pipe; 20 EGR system; 21 EGR valve; 22 EGR cooler; 23 knock sensor; 24 EGR temperature sensor; 25 EGR differential pressure sensor; 50 ECU control device. DETAILED DESCRIPTION

[0051] The present application will be described with reference to the attached drawings and preferred embodiments, which are given by way of illustration and not of limitation. The present application is shown and described in conjunction with the preferred embodiments, but it will be readily apparent to those skilled in the art that other embodiments and variations can be used without departing from the spirit and scope of the application. The preferred embodiments are merely illustrative of the present application rather than limiting the scope of the application as construed by the appended claims.

[0052] It is to be understood that the figures and embodiments provided in the following description are merely for illustrative purposes and not intended to limit the scope of the present application, as defined by the appended claims.

[0053] Referring to FIG. 1, an EGR (Exhaust Gas Recirculation) system for an engine 10 is provided. The EGR system 20 includes an EGR valve 21, an EGR cooler 22, a knock sensor 23, an EGR temperature sensor 24, an EGR differential pressure sensor 25, and an ECU control unit 50. The EGR cooler 22 is connected to the EGR valve 21. An inlet of the EGR cooler 22 is connected to an exhaust pipe of the engine 10, and an outlet of the EGR cooler 22 is connected to an inlet of the EGR valve 21. An outlet of the EGR valve 21 is connected to an inlet pipe 11 of the engine 10. The opening of the EGR valve 21 is adjustable to control the flow of exhaust gas. The exhaust gas needs to be cooled by the EGR cooler 22 before entering the inlet pipe 11 of the engine 10 to reduce the thermal shock to the engine 10. The knock sensor 23 is used to detect the knock retard amount of the engine 10. The EGR temperature sensor 24 is arranged at the outlet of the EGR cooler 22 to detect the temperature of the cooled exhaust gas. The EGR differential pressure sensor 25 is used to detect the differential pressure across the EGR valve 21. The ECU control unit is used to control the opening of the EGR valve 21 according to the operating state of the engine 10, which includes but is not limited to the speed, the load, and the temperature. The ECU control unit calculates the knock retard amount and the knock intensity according to the output signal of the knock sensor 23, and calculates the actual EGR rate and the target opening of the EGR valve 21 according to the output signals of the EGR temperature sensor 24 and the EGR differential pressure sensor 25.

[0054] To reduce the strong knock situation caused by the opening of the EGR system, an embodiment of the present application provides a control method for an EGR system of an engine, obtaining a measured knock retardation amount and a target knock retardation amount of the engine, and calculating a knock retardation deviation amount of the target knock retardation amount and the measured knock retardation amount. According to the knock retardation deviation amount, an open-loop correction coefficient of knock intensity is determined. According to the open-loop correction coefficient, the current target EGR rate is corrected to obtain a corrected target EGR rate. According to the corrected target EGR rate, the opening degree of the EGR valve body of the EGR system is adjusted.

[0055] It can be understood that in some embodiments, a control device for an EGR system of an engine is provided, comprising a processor and a memory storing program instructions, the processor being configured to execute the control method for the EGR system of the engine when the program instructions are executed.

[0056] For ease of understanding, the control method for the EGR system of the engine provided by the present application is specifically introduced below in combination with the accompanying drawings.

[0057] In some embodiments, in combination with Fig. 2, a control method for an EGR system of an engine is proposed, comprising:

[0058] S201, obtaining a measured knock retardation amount and a target knock retardation amount of the engine.

[0059] In an example, the step of obtaining the measured knock retardation amount of the engine comprises: at a current sampling time, obtaining a plurality of knock retardation amounts of the engine. The average value of the plurality of knock retardation amounts is calculated as the measured knock retardation amount of the engine.

[0060] According to the above-mentioned embodiments, at the current sampling time, the average value of the plurality of knock retardation amounts is calculated as the measured knock retardation amount by detecting the plurality of knock retardation amounts, so as to avoid the large fluctuation of the single detected knock retardation amount, and the stability of the measured knock retardation amount is improved by the average value, and the stability of the calculated knock retardation deviation amount is improved, so as to improve the accuracy of the subsequently determined open-loop correction coefficient.

[0061] Exemplarily, taking the engine as a 4-cylinder engine as an example, the calculation formula of the measured knock retardation amount is: Knockrtd_avg=(knockrtd1+knockrtd2+knockrtd3+knockrtd4) / 4

[0062] Wherein, Knockrtd_avg is the measured knock retardation amount, knockrtd1, knockrtd2, knockrtd3, knockrtd4 are respectively the latest detected knock retardation amounts of the four cylinders of the engine at the current sampling time.

[0063] In an example, the knock retard amount of the engine is detected by a knock sensor.

[0064] In a possible implementation, the processor determines the target knock retard amount according to a corresponding relationship. The corresponding relationship includes target knock retard amounts corresponding to a plurality of engine speeds and target loads. That is, under the corresponding engine speed and target load, the corresponding target knock retard amount is set to enable the reliability, combustion stability, and other indicators of the engine operation to be within the design range.

[0065] In an example, the step of determining the corresponding relationship of the target knock retard amount, the plurality of engine speeds, and the target loads includes manually changing the actual ignition angle under different engine speeds and target loads to test and verify the corresponding relationship of the target knock retard amount, the plurality of engine speeds, and the target loads. Under the corresponding engine speed and target load, the corresponding target knock retard amount is set to enable the reliability, combustion stability, and NVH indicators of the engine to be within the design range.

[0066] S202, calculating a knock retard deviation amount of the target knock retard amount and the measured knock retard amount.

[0067] According to the above embodiment, the difference between the target knock retard amount and the measured knock retard amount is the knock retard deviation amount. The knock intensity of the engine is determined by the knock retard deviation amount, and the correction coefficient is reasonably set to reduce the probability of knock occurrence.

[0068] S203, determining an open-loop correction coefficient of the knock intensity according to the knock retard deviation amount.

[0069] S204, correcting the current target EGR rate according to the open-loop correction coefficient to obtain a corrected target EGR rate.

[0070] S205, adjusting the opening of the EGR valve of the EGR system according to the corrected target EGR rate.

[0071] According to the above embodiment, during the operation of the engine, the measured knock retard amount and the target knock retard amount of the engine are obtained to determine the knock retard deviation amount. The knock intensity of the engine is fed back through the knock retard deviation amount. The open-loop correction coefficient is determined through the knock retard deviation amount. The current target EGR rate is corrected by using the open-loop correction coefficient to compensate the actual EGR rate of the EGR system to reduce the knock intensity of the engine, so that the engine can operate in a safe working state and effectively reduce the damage of abnormal knock to the engine under the open state of the EGR system.

[0072] Compared with the way of adopting the delayed ignition angle in the related art, the knock intensity is reduced. The present application starts from the aspect that the actual EGR rate is small, which is the root cause of strong knock, and corrects the target EGR rate to obtain a corrected target EGR rate. Through the corrected target EGR rate, the opening of the EGR valve is adjusted, the flow of the EGR valve is adjusted, and then the actual EGR rate of the EGR system is compensated to reduce the knock intensity of the engine. Moreover, by correcting the actual EGR rate, the control method of the present application can also solve the problem of strong engine knock caused by damage of the EGR system pipeline or the EGR cooler due to EGR hardware problems, and reduce the knock intensity of the engine.

[0073] In an example, the step of determining the open-loop correction coefficient of the knock intensity according to the knock retard deviation amount includes: in the case that the knock retard deviation amount is less than or equal to 0, determining the open-loop correction coefficient of the knock intensity as 1. That is, the target knock retard amount is less than or equal to the measured knock retard amount, in which case, it is indicated that the measured knock retard amount is greater than the target knock retard amount, and the probability of knock occurrence is low, so the open-loop correction coefficient of the knock intensity is determined as 1, and the current target EGR rate can be maintained without correction.

[0074] In an example, the step of determining the open-loop correction coefficient of the knock intensity according to the knock retard deviation amount includes: in the case that the knock retard deviation amount is greater than 0, obtaining the speed and the target load of the engine. According to the speed, the target load and the measured knock retard amount of the engine, the initial open-loop correction coefficient at the current sampling time is determined. The initial open-loop correction coefficient at the current sampling time is filtered to obtain the open-loop correction coefficient of the knock intensity.

[0075] According to the above embodiments, in the case that the knock retard deviation amount is greater than 0, that is, the target knock retard amount is greater than the measured knock retard amount, the probability of knock occurrence is high. In order to reduce the probability of knock occurrence, the current target EGR rate is corrected. Specifically, according to the speed, the target load and the measured knock retard amount of the engine, the initial open-loop correction coefficient at the current sampling time is determined, so that the measured knock retard amount can quickly reach the target knock retard amount. However, since the frequency of determining the initial open-loop correction coefficient at the current sampling time is fast, the jumping range of the determined coefficient is large, in order to reduce the disturbance, the initial open-loop correction coefficient at the current sampling time is filtered to obtain the open-loop correction coefficient of the knock intensity at the current sampling time.

[0076] In an example, the formula for determining the initial open-loop correction coefficient at the current sampling time is: Openloop_rc=Map1(Imep_s,Knockrtd_avg),

[0077] Wherein, Openloop rc is the initial open loop correction coefficient, Imep s is the target load, Knockrtd avg is the measured knock retardation amount.

[0078] According to the above embodiment, according to the obtained target load Imep s and the measured knock retardation amount Knockrtd avg of the engine, the initial open loop correction coefficient Openloop rc of the knock intensity is determined by the table lookup method. In this way, the open loop correction coefficient Openloop r of the knock intensity can be quickly determined according to the current operating condition, so as to quickly correct the current target EGR rate.

[0079] In an example, before the step of determining the initial open loop correction coefficient Openloop rc of the knock intensity according to the obtained target load Imep s and the measured knock retardation amount Knockrtd avg of the engine by the table lookup method, the method further comprises: determining a corresponding relationship table of the engine speed, the target load Imep s and the measured knock retardation amount Knockrtd avg, and the initial open loop correction coefficient Openloop rc.

[0080] In an example, the step of determining the corresponding relationship table of the engine speed, the target load Imep s and the measured knock retardation amount Knockrtd avg, and the initial open loop correction coefficient Openloop rc comprises: under the premise of closing the knock intensity closed loop correction coefficient Closeloop r, by fixing different engine speeds, target loads and measured knock retardation amounts, changing the knock open loop correction coefficient of the current operating condition, and testing; when the adjusted open loop correction coefficient makes the measured knock retardation amount Knockrtd avg controlled within the preset range of the target knock retardation amount, wherein the preset range is ± 2° of the target knock retardation amount, that is, the measured knock retardation amount Knockrtd avg is within the range of ± 2° of the target knock retardation amount, then the current open loop correction coefficient is determined as the initial open loop correction coefficient Openloop rc of the knock intensity corresponding to the current engine speed, target load and measured knock retardation amount. In this way, the corresponding relationship table of the engine speed, the target load Imep s and the measured knock retardation amount Knockrtd avg, and the initial open loop correction coefficient Openloop rc is obtained through testing and verification.

[0081] In an example, in a case where the open-loop correction coefficient of knock intensity at the previous sampling time is greater than the initial open-loop correction coefficient at the current sampling time, the open-loop correction coefficient is positively filtered to reduce the fluctuation amplitude of the open-loop correction coefficient. Specifically, a difference value between the open-loop correction coefficient of knock intensity at the previous sampling time and a preset decreasing step is calculated. The maximum value of the calculated difference value and the initial open-loop correction coefficient at the current sampling time is selected as the open-loop correction coefficient of knock intensity at the current sampling time.

[0082] In an example, in a case where the open-loop correction coefficient of knock intensity at the previous sampling time is less than the initial open-loop correction coefficient at the current sampling time, the open-loop correction coefficient is negatively filtered to reduce the fluctuation amplitude of the open-loop correction coefficient. Specifically, a sum value of the open-loop correction coefficient of knock intensity at the previous sampling time and a preset increasing step is calculated. The minimum value of the calculated sum value and the initial open-loop correction coefficient at the current sampling time is selected as the open-loop correction coefficient of knock intensity at the current sampling time.

[0083] In an example, the step of filtering the initial open-loop correction coefficient at the current sampling time to obtain the open-loop correction coefficient of knock intensity includes: in a case where the open-loop correction coefficient of knock intensity at the previous sampling time is equal to the initial open-loop correction coefficient at the current sampling time, the initial open-loop correction coefficient at the current sampling time is taken as the open-loop correction coefficient of knock intensity at the current sampling time.

[0084] In some embodiments, in combination with FIG. 3, a control method for an EGR system of an engine is proposed, including:

[0085] S301, obtaining a measured knock retardation amount of the engine and a target knock retardation amount.

[0086] S302, calculating a knock retardation deviation amount of the target knock retardation amount and the measured knock retardation amount.

[0087] S303, determining an open-loop correction coefficient of knock intensity according to the knock retardation deviation amount.

[0088] S304, obtaining an EGR valve operating condition of the EGR system.

[0089] The EGR valve operating condition includes: a vehicle speed judgment condition, a catalyst heating judgment condition, an engine water temperature condition, a lambda closed-loop condition, an air-fuel ratio enrichment condition, a start judgment condition, an engine intake air temperature condition, an EGR intake air temperature condition, and a target EGR opening degree condition.

[0090] S305, determining a closed-loop correction coefficient of knock intensity according to the knock retardation deviation amount and the EGR valve operating condition.

[0091] According to the above embodiment, when the EGR valve operating condition meets the set condition, the closed-loop correction coefficient of knock intensity is determined through the knock knockback angle deviation and the EGR valve operating condition, and the closed-loop correction coefficient is used to further improve the correction accuracy of the current target EGR rate.

[0092] The EGR valve operating condition meeting the set condition means that all the EGR valve operating conditions meet the set condition. That is, the vehicle speed judgment condition meets the condition that the vehicle speed is greater than the set vehicle speed, the catalyst heating judgment condition meets the condition that the catalyst is in a heating state, the engine water temperature condition meets the condition that the engine water temperature is greater than the set water temperature, the lambda closed-loop condition meets the condition that the lambda is in a closed-loop state, the air-fuel ratio enrichment condition meets the enrichment state, the start judgment condition meets the condition that it is in a starting state, the engine intake temperature condition meets the condition that the engine intake temperature reaches the set intake temperature, the EGR intake temperature condition meets the condition that the EGR intake temperature reaches the set intake temperature, and the target EGR opening condition meets the condition that the target EGR opening reaches the set opening.

[0093] According to the above embodiment, when all the judgment conditions of the EGR valve operating condition are monitored to meet the condition, the state value B_egri of the EGR valve operating condition monitoring is 1. When any condition of the EGR valve operating condition is monitored to not meet the set condition, the state value B_egri of the EGR valve operating condition monitoring is 0. And when the state value B_egri is 1, the closed-loop correction coefficient closeloop_r is determined. When the state value B_egri is 0, the closed-loop correction coefficient closeloop_r is 0, that is, no closed-loop correction is needed.

[0094] S306, according to the open-loop correction system and the closed-loop correction coefficient, the current target EGR rate is corrected to obtain the corrected target EGR rate.

[0095] In an example, the formula for obtaining the corrected target EGR rate is: EGR_Corr=EGR_S*(Openloop_r+Closeloop_r),

[0096] Wherein, EGR_Corr is the corrected target EGR rate, EGR_S is the current target EGR rate, Openloop_r is the open-loop correction coefficient of knock intensity, and Closeloop_r is the closed-loop correction coefficient.

[0097] According to the above embodiment, the sum of the determined open-loop correction system and closed-loop correction coefficient is multiplied by the current target EGR rate EGR_S to obtain the corrected target EGR rate.

[0098] S307, adjust the opening of the EGR valve of the EGR system according to the modified target EGR rate.

[0099] According to the above embodiment, the open-loop correction coefficient is used to quickly control the measured knock recession amount near the target knock recession amount. Then, the closed-loop correction coefficient is used to improve the correction accuracy, so as to adjust the opening of the EGR valve of the EGR system according to the modified target EGR rate, and then compensate the actual EGR rate of the EGR system, so as to reduce the knock intensity of the engine, so that the engine can operate in a safe working state, and effectively reduce the damage of abnormal knock to the engine in the open state of the EGR system.

[0100] In this way, after adjusting the opening of the EGR valve of the EGR system, the target EGR rate of the next sampling time is modified according to the control method of the above embodiment, and the iterative loop correction is performed. Through the steps of the above embodiment, the iterative loop correction of the target EGR rate is realized, and then the control of the knock intensity of the engine is realized, so that the knock intensity of the engine can be within the design range of the engine, and the damage caused by knock to the engine is reduced.

[0101] In an example, the formula for determining the closed-loop correction coefficient of the knock intensity is:

[0102] Wherein, closeloop_r is the closed-loop correction coefficient. B_egri is the state value of the EGR valve operating condition monitoring. a i is the value of the closed-loop correction integral factor, and a i is assigned according to the state value of the knock recession state monitoring. n is the sampling time sequence number, n = 1, 2, 3… Max r is the upper limit value of the integral value, and Min r is the lower limit value of the integral value.

[0103] According to the above embodiment, the closed-loop correction coefficient closeloop_r is determined according to the state value of the EGR valve operating condition monitoring. As shown in the above formula, in the case that all the EGR valve operating conditions meet the conditions, the state value B_egri of the EGR valve operating condition monitoring is 1, in this case, the closed-loop correction integral value a is calculated and compared with Max r and Min r to determine the closed-loop correction coefficient closeloop_r. In the case that the EGR valve operating conditions do not meet the conditions, the state value B_egri is 0, and the closed-loop correction coefficient closeloop_r is 0.

[0104] In an example, the formula of the closed-loop correction integral value is: In the formula, the specific value of n is determined according to the sampling times of the preset sampling frequency during the engine operation process. The preset sampling frequency can be set according to the actual working condition. Exemplarily, the preset sampling frequency is 9 ms to 11 ms, and the specific value includes but is not limited to 9 ms, 10 ms or 11 ms.

[0105] In an example, the method for determining the state value of the EGR valve operating condition monitoring includes monitoring the EGR valve operating condition, which includes the vehicle speed judgment condition, the catalyst heating judgment condition, the engine water temperature judgment condition, the lambda closed loop condition, the air-fuel ratio enrichment condition, the start judgment condition, the engine intake air temperature condition, the EGR intake air temperature condition and the target EGR opening degree condition. In the case where all the set conditions of the EGR valve operating condition are met, the state value B_egri of the EGR valve operating condition monitoring is 1. In the case where any of the set conditions of the EGR valve operating condition is not met, the state value B_egri is 0.

[0106] According to the above embodiment, in the case where all the judgment conditions of the EGR valve operating condition are met, the state value B_egri of the EGR valve operating condition monitoring is 1, otherwise the state value B_egri is 0. And in the case where the state value B_egri is 1, the closed loop correction coefficient closeloop_r is determined. In the case where the state value B_egri is 0, the closed loop correction coefficient closeloop_r is 0, that is, no closed loop correction is needed. In the case where all the judgment conditions of the EGR valve operating condition are met, the protection of the hardware such as the EGR valve is realized to ensure the stability of the engine combustion.

[0107] In an example, the state value of the knockback angle state monitoring is used to assign the value of ɑ i In the case where the actual knockback angle is greater than the target knockback angle, the knock intensity judgment condition outputs 1, otherwise 0. In the case where the actual EGR rate is greater than the target EGR rate, the EGR rate judgment condition outputs 1, otherwise 0. In the case where the knock intensity judgment condition, the EGR rate judgment condition and the engine misfire judgment condition all output 1, the state value B_egrknck of the knockback angle state monitoring outputs 1, otherwise 0. In the case where B_egrknck outputs 1, ɑ i equals the negative integral factor INT_down. In the case where B_egrknck outputs 0, ɑ i equals the positive integral factor INT_up.

[0108] According to the above embodiment, the state value output by the knockback angle state monitoring is used to assign the value of ɑ iThe assignment is performed. Specifically, the knock recession state monitoring condition includes a knock intensity judgment condition, an EGR rate judgment condition, and an engine misfire judgment condition. In the case where the knock intensity judgment condition, the EGR rate judgment condition, and the engine misfire judgment condition all output 1, the state value B_egrknck of the knock recession state monitoring outputs 1, and otherwise outputs 0. When B_egrknck outputs 1, a i equals the negative integral factor INT_down. When B_egrknck outputs 0, a i equals the positive integral factor INT_up. In this way, according to the state value output by the knock recession state monitoring, it is determined whether a i is corrected by positive or negative integral, so that the measured knock recession amount is closer to the target knock recession amount. Engine misfire is prone to calculation deviation, which in turn leads to unstable engine combustion and aggravates the misfire problem. In this way, the knock recession state is monitored to enable closed-loop correction under normal engine operating conditions.

[0109] In an example, the negative integral factor INT_down has a value range of less than or equal to 0 and greater than or equal to -1. The positive integral factor INT_up has a value range of greater than or equal to 0 and less than or equal to 1.

[0110] In some embodiments, in combination with FIG. 4, a control method for an EGR system of an engine is proposed, comprising:

[0111] S401, obtaining a measured knock recession amount and a target knock recession amount of the engine.

[0112] S402, calculating a knock recession deviation amount of the target knock recession amount and the measured knock recession amount.

[0113] S403, determining an open-loop correction coefficient of knock intensity according to the knock recession deviation amount.

[0114] S404, judging whether the knock recession deviation amount is less than or equal to 0. In the case where the result is yes, proceed to S405. In the case where the result is no, proceed to S406.

[0115] S405, in the case where the knock recession deviation amount is less than or equal to 0, determining that the open-loop correction coefficient of knock intensity is 1.

[0116] S406, in the case where the knock recession deviation amount is greater than 0, obtaining a speed and a target load of the engine.

[0117] S407, determining an initial open-loop correction coefficient at the current sampling time according to the speed, the target load, and the measured knock recession amount of the engine.

[0118] S408, in a case where the open-loop correction coefficient of knock intensity at the previous sampling time is greater than the initial open-loop correction coefficient at the current sampling time, calculating a difference value between the open-loop correction coefficient of knock intensity at the previous sampling time and a preset decreasing step.

[0119] S409, selecting a maximum value between the calculated difference value and the initial open-loop correction coefficient at the current sampling time as the open-loop correction coefficient of knock intensity.

[0120] S410, in a case where the open-loop correction coefficient of knock intensity at the previous sampling time is less than the initial open-loop correction coefficient at the current sampling time, calculating a sum value of the open-loop correction coefficient of knock intensity at the previous sampling time plus a preset increasing step;

[0121] S411, selecting a minimum value between the calculated sum value and the open-loop correction coefficient value at the current sampling time as the open-loop correction coefficient of knock intensity.

[0122] S412, in a case where the open-loop correction coefficient of knock intensity at the previous sampling time is equal to the initial open-loop correction coefficient at the current sampling time, taking the initial open-loop correction coefficient at the current sampling time as the open-loop correction coefficient of knock intensity.

[0123] S413, obtaining an EGR valve operating condition of an EGR system.

[0124] S414, in a case where any one of the EGR valve operating conditions does not meet the condition, the closed-loop correction coefficient closeloop_r is 0.

[0125] S415, in a case where all the EGR valve operating conditions meet the set condition, determining a state value of knock back angle state monitoring.

[0126] S416, in a case where the state value of knock back angle state monitoring is output as 1, ɑ i is equal to a negative integral factor INT_down.

[0127] S417, in a case where the state value of knock back angle state monitoring is output as 0, ɑ i is equal to a positive integral factor INT_up.

[0128] S418, calculating a closed-loop correction integral value of the closed-loop correction integral factor at n sampling times.

[0129] S419, in a case where the closed-loop correction integral value is between Mɑx r and Min r , determining that the closed-loop correction coefficient closeloop_r is equal to the closed-loop correction integral value.

[0130] S420, in the case that the closed-loop correction integral value is greater than or equal to Max, determining that the closed-loop correction coefficient closeloop_r is equal to Max r . r .

[0131] S421, in the case that the closed-loop correction integral value is less than or equal to Min r . r .

[0132] S422, correcting the current target EGR rate according to the open-loop correction system and the closed-loop correction coefficient, to obtain a corrected target EGR rate.

[0133] S423, adjusting the opening of the EGR valve of the EGR system according to the corrected target EGR rate.

[0134] According to the above embodiment, the knock intensity of the engine is determined by detecting the knock recession amount of the engine. According to the knock recession deviation amount between the target knock recession amount and the measured knock recession amount, the open-loop correction coefficient and the closed-loop correction coefficient for correcting the current target EGR rate under different working conditions are determined. The current target EGR rate is corrected according to the open-loop correction coefficient and the closed-loop correction coefficient, to obtain a corrected target EGR rate. The opening of the EGR valve is adjusted according to the corrected target EGR rate, to compensate for the actual EGR rate under different working conditions, so as to control the knock intensity of the engine, so that the engine can operate in a safe working state, and effectively reduce the damage of abnormal knock in the EGR open state to the engine.

[0135] In some embodiments, as shown in FIG. 5, a control device 50 for an EGR system of an engine is provided, comprising

[0136] The knock monitoring module 501 is configured to obtain the measured knock recession amount and the target knock recession amount of the engine, and calculate the knock recession deviation amount between the target knock recession amount and the measured knock recession amount.

[0137] The EGR open-loop correction module 502 is configured to determine the open-loop correction coefficient of the knock intensity according to the knock recession deviation amount, and correct the current target EGR rate according to the open-loop correction coefficient, to obtain a corrected target EGR rate.

[0138] The EGR valve control module 503 is configured to adjust the opening of the EGR valve of the EGR system according to the corrected target EGR rate.

[0139] The application is a control device 50 for an EGR system of an engine. The knock intensity of the engine is determined by detecting the knock back angle amount of the engine. According to the knock back angle deviation between the target knock back angle amount and the measured knock back angle amount, the open-loop correction coefficient of the current target EGR rate under different working conditions is determined and corrected to obtain the corrected target EGR rate. According to the corrected target EGR rate, the opening degree of the EGR valve is controlled to compensate the actual EGR rate under different working conditions, so as to control the knock intensity of the engine, so that the engine can operate in a safe working state and effectively reduce the damage of abnormal knock to the engine under the EGR opening state.

[0140] In an example, the EGR open-loop correction module is further configured to determine the open-loop correction coefficient of the knock intensity as 1 when the knock back angle deviation is less than or equal to 0. When the knock back angle deviation is greater than 0, the engine speed and the target load are obtained. According to the engine speed, the target load and the measured knock back angle amount, the initial open-loop correction coefficient at the current sampling time is determined. The initial open-loop correction coefficient at the current sampling time is filtered to obtain the open-loop correction coefficient of the knock intensity.

[0141] In an example, in combination with FIG. 6, the control device 50 further comprises an EGR closed-loop correction module 504. The EGR closed-loop correction module is configured to determine the closed-loop correction coefficient of the knock intensity according to the knock back angle deviation and the EGR valve operating condition.

[0142] The EGR closed-loop correction module 504 comprises an EGR valve operating condition monitoring module 5042, a knock back angle state monitoring module 5044 and a closed-loop correction integral value calculation module 5046. The EGR valve operating condition monitoring module 5042 is configured to monitor whether the EGR valve operating condition meets the set condition and output a state value. The knock back angle state monitoring module 5046 is configured to output a state value for monitoring the knock back angle state.

[0143] In an example, in combination with FIG. 7, the determination method of the state value of the EGR valve operating condition monitoring module 5042 comprises monitoring the EGR valve operating condition, which comprises vehicle speed judgment condition, catalyst heating judgment condition, engine water temperature condition, lambda closed-loop condition, air-fuel ratio enrichment condition, starting judgment condition, engine intake air temperature condition, EGR intake air temperature condition and target EGR opening degree condition. When all the EGR valve operating conditions meet the conditions, the state value B_egri of the EGR valve operating condition monitoring module is 1, otherwise the state value B_egri is 0.

[0144] According to the above embodiment, in the case where all the judgment conditions of the EGR valve operation condition monitoring module 5042 are monitored and all the conditions are satisfied, the state value B_egri of the EGR valve operation condition monitoring module is 1, otherwise the state value B_egri is 0. And in the case where the state value B_egri is 1, the closed loop correction coefficient closeloop_r is determined. In the case where the state value B_egri is 0, the closed loop correction coefficient closeloop_r is 0, that is, no closed loop correction is needed.

[0145] In an example, in combination with FIG. 8, the step of the knockback angle state monitoring module 5044 outputting the state value of the knockback angle state includes: in the case where the actual knockback angle is greater than the target knockback angle, the knock intensity judgment condition outputs 1, otherwise 0. In the case where the actual EGR rate is greater than the target EGR rate threshold, the EGR rate judgment condition outputs 1, otherwise 0. In the case where the knock intensity judgment condition, the EGR rate judgment condition and the engine misfire judgment condition all output 1, the state value B_egrknck of the knockback angle state monitoring module outputs 1. In the case where any of the knock intensity judgment condition, the EGR rate judgment condition and the engine misfire judgment condition outputs 0, 0 is outputted.

[0146] In an example, according to the state value of the knockback angle state monitoring module 5044, the step of assigning values to ɑ i includes: in the case where B_egrknck outputs 1, ɑ i is equal to the negative integral factor INT_down. In the case where B_egrknck outputs 0, ɑ i is equal to the positive integral factor INT_up. The value range of the negative integral factor INT_down is less than or equal to 0, greater than or equal to -1. The value range of the positive integral factor INT_up is greater than or equal to 0, less than or equal to 1.

[0147] In an example, the closed loop correction integral value calculation module 5046 calculates the closed loop correction integral value of the closed loop correction integral factor at n sampling time points according to the formula , where n = 1, 2, 3, ….

[0148] With reference to FIG. 9, the disclosure provides a control device 80 for an EGR system of an engine, comprising a processor 801 and a memory 802. Optionally, the device 80 can further comprise a communication interface 803 and a bus 804. The processor 801, the communication interface 803 and the memory 802 can communicate with each other through the bus 804. The communication interface 803 can be used for information transmission. The processor 801 can invoke the logic instructions in the memory 802 to execute the control method of the EGR system of the engine according to the above embodiments.

[0149] In addition, the logic instructions in the memory 802 can be implemented in the form of a software function unit and sold or used as an independent product, which can be stored in a computer readable storage medium.

[0150] The memory 802 as a computer readable storage medium can be used to store software programs, computer executable programs, such as program instructions / modules corresponding to the method in the embodiments of the disclosure. The processor 801 executes the program instructions / modules stored in the memory 802 to perform function applications and data processing, that is, to implement the control method of the EGR system of the engine according to the above embodiments.

[0151] The memory 802 can include a program storage area and a data storage area. The program storage area can store an operating system and at least one application required by a function; the data storage area can store data created according to the use of the terminal device, etc. In addition, the memory 802 can include a high-speed random access memory, and can further include a nonvolatile memory.

[0152] In some embodiments, a computer readable storage medium is provided, which stores program instructions. When the program instructions are executed, the computer is caused to execute the control method of the EGR system of the engine according to any one of the above embodiments.

[0153] In some embodiments, a vehicle is provided, which comprises the control device of the EGR system of the engine according to any one of the above embodiments.

[0154] The vehicle according to the embodiment of the present disclosure includes a vehicle body, an engine, an EGR system, and the control device 50 (80) for the EGR system of the engine described above. The control device 50 (80) for the EGR system of the engine is installed in the vehicle body. The installation relationship described herein is not limited to being placed inside the vehicle body, but also includes installation connection with other components of the vehicle, including but not limited to physical connection, electrical connection, or signal transmission connection, etc. Those skilled in the art can understand that the control device 50 (80) for the EGR system of the engine can be adapted to the available vehicle body, and thus realize other available embodiments.

[0155] The above embodiments are only preferred embodiments for fully illustrating the present disclosure, and the protection scope of the present disclosure is not limited thereto. Any equivalent replacement or transformation of the present disclosure made by those skilled in the art based on the present disclosure is within the protection scope of the present disclosure. The embodiments only represent possible variations. Unless explicitly required, individual components and functions are optional, and the order of operations can be changed. Parts and features of some embodiments can be included in or replaced by parts and features of other embodiments. Moreover, the words used in the present application are only used to describe the embodiments and not to limit the claims. As used in the description of the embodiments and the claims, unless the context clearly indicates otherwise, the singular forms "a", "an", and "the" are intended to include the plural forms as well. Similarly, as used in the present application, the term "and / or" refers to any and all possible combinations of one or more associated listed items. In addition, when used in the present application, the term "comprise" and its variants "comprises" and / or comprises" and the like mean the presence of the stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups of these. Without more limitations, the element defined by the phrase "comprising a" does not exclude the presence of additional identical elements in the process, method, or device comprising the element. In this document, each embodiment can focus on the difference from other embodiments, and the same or similar parts between embodiments can be referred to each other. For the method, product, etc. disclosed in the embodiments, if it corresponds to the method part disclosed in the embodiments, the relevant part can be referred to the description of the method part.

[0156] Those skilled in the art can understand that the units and algorithm steps of each example described in combination with the embodiments disclosed herein can be realized by electronic hardware or a combination of computer software and electronic hardware. Whether the functions are realized in hardware or software depends on the specific application and design constraints of the technical solution. The skilled person can use different methods for each specific application to realize the described functions, but such implementation should not be considered beyond the scope of the embodiments of the present disclosure. The skilled person can clearly understand that, for the convenience and brevity of description, the specific working processes of the above-described system, device and unit can refer to the corresponding processes in the foregoing method embodiments, which will not be repeated here.

[0157] In the embodiments disclosed herein, the disclosed methods, products (including but not limited to devices, equipment, etc.) can be implemented in other ways. For example, the above-described device embodiments are only schematic, for example, the division of the units can only be a logical function division, and actual implementation can have another division manner, for example, a plurality of units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the coupling or direct coupling or communication connection between the units shown or discussed can be indirect coupling or communication connection through some interface, device or unit, and can be electrical, mechanical or other forms. The units described as separate components can or can not be physically separate, and the components shown as units can or can not be physical units, that is, they can be located in one place, or can be distributed on a plurality of network units. Part or all of the units can be selected according to actual needs to implement the embodiments. In addition, each functional unit in the embodiments of the present disclosure can be integrated in one processing unit, or each unit can be a physically independent unit, or two or more units can be integrated in one unit.

[0158] The computer program instructions can also be loaded onto a computer, other programmable data processing apparatus, or other processing device to cause a series of operational steps to be performed on the computer, other programmable apparatus or other processing device to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide processes for implementing the functions / acts specified in the flowchart and / or block diagram block or blocks.

Claims

1. A control method for an EGR system of an engine, characterized by: The method comprises the following steps: acquiring a measured knock retardation amount and a target knock retardation amount of the engine, and calculating a knock retardation deviation amount between the target knock retardation amount and the measured knock retardation amount; determining an open-loop correction coefficient of knock intensity according to the knock retardation deviation amount; correcting a current target EGR rate according to the open-loop correction coefficient to obtain a corrected target EGR rate; adjusting the opening degree of an EGR valve of an EGR system according to the corrected target EGR rate.

2. The control method according to claim 1, characterized by: The step of determining the open-loop correction coefficient of knock intensity according to the knock retardation deviation amount comprises: in the case that the knock retardation deviation amount is less than or equal to 0, determining the open-loop correction coefficient of knock intensity as 1; in the case that the knock retardation deviation amount is greater than 0, acquiring the speed and target load of the engine; determining an initial open-loop correction coefficient of the current sampling time according to the speed of the engine, the target load and the measured knock retardation amount; filtering the initial open-loop correction coefficient of the current sampling time to obtain the open-loop correction coefficient of knock intensity of the current sampling time.

3. The control method according to claim 2, characterized in that: The formula for determining the initial open-loop correction coefficient of the current sampling time is: Openloop_rc=Map1(Imep_s,Knockrtd_avg), wherein, Openloop_rc is the initial open-loop correction coefficient, Imep_s is the target load, and Knockrtd_avg is the measured knock retardation amount.

4. The control method according to claim 2, characterized by: The step of filtering the initial open-loop correction coefficient of the current sampling time to obtain the open-loop correction coefficient of knock intensity of the current sampling time comprises: in the case that the open-loop correction coefficient of knock intensity of the previous sampling time is greater than the initial open-loop correction coefficient of the current sampling time, calculating the difference between the open-loop correction coefficient of knock intensity of the previous sampling time and a preset decrement step; selecting the maximum value between the calculated difference and the initial open-loop correction coefficient of the current sampling time as the open-loop correction coefficient of knock intensity of the current sampling time; or in the case that the open-loop correction coefficient of knock intensity of the previous sampling time is less than the initial open-loop correction coefficient of the current sampling time, calculating the sum of the open-loop correction coefficient of knock intensity of the previous sampling time and a preset increment step; selecting the minimum value between the calculated sum and the initial open-loop correction coefficient of the current sampling time as the open-loop correction coefficient of knock intensity of the current sampling time; or in the case that the open-loop correction coefficient of knock intensity of the previous sampling time is equal to the initial open-loop correction coefficient of the current sampling time, taking the initial open-loop correction coefficient of the current sampling time as the open-loop correction coefficient of knock intensity of the current sampling time.

5. The control method according to any one of claims 1 to 4, characterized by The step of correcting the current target EGR rate according to the open-loop correction coefficient to obtain the corrected target EGR rate comprises: acquiring the EGR valve operating condition of the EGR system; determining a closed-loop correction coefficient of knock intensity according to the knock retardation deviation amount and the EGR valve operating condition; According to the open-loop correction system and the closed-loop correction coefficient, a current target EGR rate is corrected to obtain a corrected target EGR rate.

6. The control method according to claim 5, characterized in that: The formula for obtaining the corrected target EGR rate is: EGR_Corr = EGR_S × (Openloop_r + Closeloop_r), wherein EGR_Corr is the corrected target EGR rate, EGR_S is the current target EGR rate, Openloop_r is the open-loop correction coefficient of knock intensity, and Closeloop_r is the closed-loop correction coefficient of knock intensity.

7. The control method according to claim 5, characterized by: The formula for determining the closed-loop correction coefficient of knock intensity is: Wherein, closeloop_r is the closed loop correction coefficient; B_egr i is the state value of EGR valve operating condition monitoring; ɑ i is the value of closed loop correction integral factor, and according to the state value of knock back angle state monitoring, ɑ i is assigned; n is the sampling time sequence number, n = 1, 2, 3…; Max r is the upper limit value of closed loop correction integral value, Min r is the lower limit value of closed loop correction integral value.

8. The control method according to claim 7, characterized in that: The method for determining the state value of the EGR valve operating condition monitoring includes: monitoring the EGR valve operating condition, which includes: vehicle speed judgment condition, catalytic converter heating judgment condition, engine water temperature condition, lambda closed-loop condition, air-fuel ratio enrichment condition, starting judgment condition, engine intake air temperature condition, EGR intake air temperature condition, and target EGR opening condition; In the case where all of the EGR valve operating conditions satisfy the set conditions, the state value B_egr of the EGR valve operating condition monitoring is 1, otherwise it is 0. i is 1, otherwise the state value B_egr i is 0.

9. The control method according to claim 7, characterized by: According to the state value of knock recession angle state monitoring, ɑ i The step of assigning includes: when the actual knock recession angle amount is greater than the target knock recession angle amount, the knock intensity judgment condition outputs 1, and vice versa; when the actual EGR rate is greater than the target EGR rate, the EGR rate judgment condition outputs 1, and vice versa; when the knock intensity judgment condition, the EGR rate judgment condition, and the engine misfire diagnosis output are all 1, the state value B_egrknck of the knock recession angle state monitoring outputs 1, and vice versa; At B_egrknck output is 1, ɑ i equals negative integration factor INT_down; At B_egrknck output 0, ɑ i is equal to the positive integration factor INT_up.

10. The control method according to claim 9, characterized in that: the conditions for the knock recession angle state monitoring include: knock intensity judgment condition, EGR rate judgment condition, and engine misfire judgment condition.

11. The control method according to claim 9, characterized by: The value range of the negative integral factor INT_down is less than or equal to 0, and greater than or equal to -1; The value range of the positive integral factor INT_up is greater than or equal to 0, and less than or equal to 1.

12. The control method according to any one of claims 1 to 4, characterized by: The step of obtaining the actual knock recession angle amount of the engine includes: at the current sampling time, obtaining the knock recession angle amounts of multiple cylinders of the engine; calculating the average value of the multiple knock recession angle amounts as the actual knock recession angle amount of the engine.

13. A control device for an EGR system of an engine, characterized by, It includes: a knock monitoring module for obtaining the actual knock recession angle amount and the target knock recession angle amount of the engine, and calculating the knock recession angle deviation amount between the target knock recession angle amount and the actual knock recession angle amount; an EGR open-loop correction module for determining the open-loop correction coefficient of knock intensity according to the knock recession angle deviation amount, and correcting the current target EGR rate according to the open-loop correction coefficient to obtain a corrected target EGR rate; an EGR valve control module for adjusting the opening of the EGR valve body of the EGR system according to the corrected target EGR rate.

14. The control device of claim 13, wherein, It also includes: an EGR closed-loop correction module for determining the closed-loop correction coefficient of knock intensity according to the knock recession angle deviation amount and the EGR valve operating condition.

15. The control device of claim 14, wherein, The EGR closed-loop correction module includes: an EGR valve operating condition monitoring module for monitoring whether the EGR valve operating condition meets the set condition and outputting a state value; a knock recession angle state monitoring module for outputting a state value of monitoring the knock recession angle state; a closed loop correction integral value calculation module according to the formula The closed-loop correction integral value of the closed-loop correction integral factor is calculated at n sampling time points, where ɑ i is the value of the closed-loop correction integral factor, n = 1, 2, 3, … 16. The control device of claim 14, wherein The EGR open-loop correction module is further configured to determine the open-loop correction coefficient of knock intensity as 1 when the knock back angle deviation is less than or equal to 0. The EGR open-loop correction module is further configured to obtain the engine speed and the target load when the knock back angle deviation is greater than 0, and determine the initial open-loop correction coefficient at the current sampling time according to the engine speed, the target load and the measured knock back angle.

17. A control device for an EGR system of an engine, characterized by: The processor is configured to determine the target knock back angle according to a corresponding relationship when executing the program instructions, wherein the corresponding relationship comprises a plurality of target knock back angles corresponding to a plurality of engine speeds and target loads.

18. The control device of claim 17, wherein: The processor is configured to determine the target knock back angle according to a corresponding relationship, wherein the corresponding relationship comprises a plurality of target knock back angles corresponding to a plurality of engine speeds and target loads. The processor is configured to determine the target knock back angle according to a corresponding relationship, wherein the corresponding relationship comprises a plurality of target knock back angles corresponding to a plurality of engine speeds and target loads. The processor is configured to determine the target knock back angle according to a corresponding relationship, wherein the corresponding relationship comprises a plurality of target knock back angles corresponding to a plurality of engine speeds and target loads.

19. A computer-readable storage medium storing program instructions, characterized in that, The processor is configured to determine the target knock back angle according to a corresponding relationship, wherein the corresponding relationship comprises a plurality of target knock back angles corresponding to a plurality of engine speeds and target loads.

20. A vehicle characterized by The program instructions, when executed, cause the computer to perform the control method of the EGR system for the engine according to any one of claims 1 to 12. The processor is configured to determine the target knock back angle according to a corresponding relationship, wherein the corresponding relationship comprises a plurality of target knock back angles corresponding to a plurality of engine speeds and target loads. The processor is configured to determine the target knock back angle according to a corresponding relationship, wherein the corresponding relationship comprises a plurality of target knock back angles corresponding to a plurality of engine speeds and target loads.

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