EGR rate control method, apparatus, and device, and storage medium

Abstract

An EGR rate control method, which is applied to a low-pressure EGR system. The method comprises: when an engine is in a warm-up state, acquiring the temperature of a coolant in an air cylinder of the engine and the misfire rate of the engine; and correcting a preset maximum EGR rate on the basis of the temperature of the coolant and the misfire rate to obtain a target EGR rate. Further provided are an EGR rate control apparatus, an EGR rate control device, and a computer-readable storage medium. In an engine warm-up process of the low-pressure EGR system, the preset maximum EGR rate is corrected on the basis of the temperature of the coolant and the misfire rate, so that the EGR rate can be reduced, and the probability of an engine combustion misfire is further reduced.

Description

EGR rate control method, device, equipment and storage medium CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to Chinese patent application No. 2024103049691 filed on March 18, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0002] The present application belongs to the field of low-pressure EGR technology, and in particular relates to an EGR rate control method, device, equipment and storage medium. Background Art

[0003] To improve the thermal efficiency of gasoline engines, various companies have begun researching and mass-producing gasoline engines that utilize low-pressure exhaust gas recirculation (EGR) systems. Compared to traditional high-pressure EGR systems, low-pressure EGR systems significantly expand the engine's available EGR range, meeting the EGR requirements of common hybrid engine operating conditions and thus reducing fuel consumption.

[0004] Currently, low-pressure EGR systems are typically used with high-compression ratio engines to achieve higher EGR rates and reduce fuel consumption. However, high EGR rates can lead to deteriorating engine combustion under non-standard operating conditions. This is particularly common during engine warm-up, when cylinder temperatures are low. High EGR rates can lead to unstable combustion and even misfires. Therefore, controlling the EGR rate to reduce the probability of engine misfires is a pressing issue. Summary of the Invention

[0005] The technical solution of the present application provides an EGR rate control method, device, equipment and storage medium, which can reduce the probability of engine combustion misfire at least to a certain extent.

[0006] Other features and advantages of the present application will become apparent from the following detailed description, or may be learned in part by practice of the present application.

[0007] According to a first aspect of the technical solution of the present application, an EGR rate control method is provided, which is applied to a low-pressure EGR system, comprising:

[0008] When the engine is in a warm-up state, obtaining a coolant temperature in a cylinder of the engine and a misfire rate of the engine;

[0009] The preset maximum EGR rate is corrected according to the coolant temperature and the misfire rate to obtain a target EGR rate.

[0010] In some technical solutions of the present application, based on the aforementioned solution, the preset maximum EGR rate is corrected according to the coolant temperature and the misfire rate to obtain the target EGR rate, including:

[0011] determining a first target correction coefficient corresponding to the coolant temperature;

[0012] When the misfire rate is less than or equal to a first preset value and the coolant temperature is within a preset temperature range, the preset maximum EGR rate is corrected using the first target correction coefficient to obtain the target EGR rate;

[0013] When the misfire rate is greater than the first preset value and the coolant temperature is within a preset temperature range, the first target correction coefficient is reduced to a second target correction coefficient, and the preset maximum EGR rate is corrected using the second target correction coefficient to obtain the target EGR rate.

[0014] In some technical solutions of the present application, based on the aforementioned solution, determining the first target correction coefficient corresponding to the coolant temperature includes:

[0015] searching a target correction coefficient corresponding to the coolant temperature from a preset mapping relationship, wherein the preset mapping relationship is used to represent a correspondence between the coolant temperature and the target correction coefficient;

[0016] The found target correction coefficient is determined as the first target correction coefficient.

[0017] In some technical solutions of the present application, based on the above solution, the EGR rate control method further includes:

[0018] The EGR rate of the test engine was adjusted in steps at different coolant temperatures;

[0019] When the combustion cycle variation of the test engine and the misfire rate of the test engine meet a first preset condition, determining an initial correction coefficient corresponding to different coolant temperatures according to the adjusted EGR rate to obtain an initial mapping relationship;

[0020] Performing a World Light Vehicle Test Cycle (WLTC) test on the test engine according to the initial mapping relationship, and adjusting the initial correction coefficient;

[0021] When the combustion cycle variation of the test engine and the misfire rate of the test engine meet a second preset condition, the preset mapping relationship is obtained according to the adjusted initial correction coefficients corresponding to different coolant temperatures.

[0022] In some technical solutions of the present application, based on the aforementioned solution, when the misfire rate is greater than the first preset value, reducing the first target correction coefficient to a second target correction coefficient includes:

[0023] When the misfire rate is greater than the first preset value and less than or equal to a second preset value, the first target correction coefficient is reduced according to a preset step size until the misfire rate is less than the first preset value, and the reduced first target correction coefficient is determined as the second target correction coefficient.

[0024] In some technical solutions of the present application, based on the aforementioned solution, when the misfire rate is greater than the first preset value, reducing the first target correction coefficient to a second target correction coefficient includes:

[0025] When the misfire rate is greater than the second preset value, the first target correction coefficient is directly reduced to a second target correction coefficient, wherein the second preset correction coefficient is equal to zero.

[0026] In some technical solutions of the present application, based on the above solution, the EGR rate control method further includes:

[0027] When the misfire rate is less than a third preset value and the coolant temperature is within a preset temperature range, the preset maximum EGR rate is corrected using the first target correction coefficient, and the corrected EGR rate is added to a preset ratio to obtain the target EGR rate; wherein the third preset value is less than the first preset value.

[0028] According to a second aspect of the technical solution of the present application, an EGR rate control device is provided, which is applied to a low-pressure EGR system, comprising:

[0029] a data acquisition module, configured to acquire a coolant temperature in a cylinder of the engine and a misfire rate of the engine when the engine is in a warm-up state;

[0030] The EGR rate correction module is used to correct the preset maximum EGR rate according to the coolant temperature and the misfire rate to obtain a target EGR rate.

[0031] According to the third aspect of the technical solution of the present application, an EGR rate control device is provided, comprising a processor and a memory, wherein the memory stores computer program instructions that can be executed by the processor, and when the processor executes the computer program instructions, the steps of the method described in any one of the first aspects above are implemented.

[0032] According to the fourth aspect of the technical solution of the present application, a computer-readable storage medium is provided, in which computer program instructions are stored. When the computer program instructions are executed by a processor, the processor is prompted to implement the steps of the method described in any one of the first aspects above.

[0033] In this application, while the engine is warming up, the coolant temperature in the cylinders of the engine and the engine misfire rate are obtained; a preset maximum EGR rate is corrected based on the coolant temperature and the misfire rate to obtain a target EGR rate. By correcting the preset maximum EGR rate based on the coolant temperature and the misfire rate during the engine warm-up process in a low-pressure EGR system, the EGR rate can be reduced, thereby reducing the probability of engine misfire.

[0034] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The accompanying drawings are incorporated into and constitute a part of the specification, illustrating the technical solutions of the present application and, together with the specification, explaining the principles of the present application. Obviously, the drawings described below are only some of the technical solutions of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without inventive work. In the drawings:

[0036] FIG1 shows a schematic structural diagram of a low-pressure EGR system in a technical solution;

[0037] FIG2 shows a schematic flow chart of an EGR rate control method in a technical solution;

[0038] FIG3 shows a block diagram of an EGR rate control device in a technical solution;

[0039] FIG4 shows a schematic structural diagram of an EGR rate control device in a technical solution. DETAILED DESCRIPTION

[0040] The following will be combined with the accompanying drawings of the technical solutions of this application to clearly and completely describe the technical solutions in the technical solutions of this application. Obviously, the technical solutions described are only part of the technical solutions of this application, not all of the technical solutions. Based on the technical solutions in this application, all other technical solutions obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0041] In addition, described feature, structure or characteristic can be combined in one or more technical schemes in any suitable manner.In the following description, many specific details are provided so as to provide a full understanding of the technical scheme of the present application. However, it will be appreciated by those skilled in the art that the technical scheme of the present application can be put into practice without one or more of the specific details, or other methods, components, devices, steps etc. can be adopted. In other cases, known methods, devices, implementations or operations are not shown or described in detail to avoid blurring the various aspects of the application.

[0042] The block diagrams shown in the accompanying drawings are merely functional entities and do not necessarily correspond to physically separate entities. That is, these functional entities may be implemented in software, in one or more hardware modules or integrated circuits, or in different networks and / or processor devices and / or microcontroller devices.

[0043] The flowcharts shown in the accompanying drawings are for illustrative purposes only and do not necessarily include all contents and operations / steps, nor must they be executed in the order described. For example, some operations / steps may be decomposed, while others may be combined or partially combined. Therefore, the actual execution order may vary depending on the actual situation.

[0044] It should also be noted that the terms "first," "second," and the like in the specification and claims of this application and the accompanying drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or precedence. It should be understood that the terms used in this manner are interchangeable where appropriate, so that the technical solutions of this application described herein can be implemented in an order other than that illustrated or described.

[0045] In order to enable those skilled in the art to better understand the present application, the low-pressure EGR system involved in the present application is first briefly described with reference to FIG1 .

[0046] Figure 1 shows a schematic diagram of the low-pressure EGR system in one technical solution. As shown in Figure 1, the low-pressure EGR system can include a throttle module, a mixing valve module, an EGR valve module, a supercharger module, an EGR cooler, an intercooler, a catalyst, a gasoline particulate filter (GPF), an air filter, and other equipment. The throttle module includes a throttle valve and its corresponding actuator, the mixing valve module includes a mixing valve and its corresponding actuator, the EGR valve module includes an EGR valve and its corresponding actuator, and the supercharger module includes a supercharger and its corresponding actuator.

[0047] The low-pressure EGR system extracts exhaust gas from the GPF, which then passes through the EGR cooler and EGR valve module before entering the compressor line. The air then passes through the air filter and mixing valve module, mixing with the exhaust gas in the compressor line. The air then enters the compressor, passing through the intercooler and throttle module and into the engine cylinders. The mixing valve module is installed between the air filter and the compressor, and the EGR valve module's outlet line is installed between the mixing valve and the compressor. When the low-pressure EGR system is required, the mixing valve needs to be closed to a smaller opening, creating a negative pressure downstream of the low-pressure EGR system. This creates a pressure differential across the EGR valve, allowing the mixed gas to enter the cylinders.

[0048] Engines used with low-pressure EGR systems typically have high compression ratios. During engine warm-up, when the coolant temperature in the engine cylinders is low, high EGR rates can lead to unstable combustion and even misfires. This technical solution reduces the probability of engine misfires and lowers fuel consumption by lowering the EGR rate based on coolant temperature and misfire rate.

[0049] FIG2 shows a schematic flow chart of an EGR rate control method in a technical solution. As shown in FIG2 , an EGR rate control method is provided, which may include the following steps 201 to 202 .

[0050] In step 201 , when the engine is in a warm-up state, the coolant temperature in the cylinder of the engine and the misfire rate of the engine are obtained.

[0051] It can be understood that engine warm-up refers to the process of letting the engine run for a period of time after starting the vehicle so that it reaches a suitable operating temperature.

[0052] The coolant temperature refers to the temperature of the coolant in the cylinder, such as water temperature, which can be measured by a temperature detection device in the cylinder.

[0053] The misfire rate of an engine refers to the proportion of misfires occurring per a preset number of engine ignitions (e.g., 1,000 times), and the misfire rate can be measured by a combustion analyzer.

[0054] In step 202 , the preset maximum EGR rate is corrected according to the coolant temperature and the misfire rate to obtain a target EGR rate.

[0055] It is understood that the preset maximum EGR rate is the full EGR rate. During the warm-up process, the EGR rate control strategy can be to disable the low-pressure EGR system below 60 degrees Celsius, while using the full EGR rate above 60 degrees Celsius. When the EGR rate is high, even if the coolant temperature is between 60 and 90 degrees Celsius, the engine will still experience misfires, resulting in deteriorated combustion, increased fuel consumption, and rough engine operation. The technical solution of this application reduces the EGR rate according to the coolant temperature and misfire rate, thereby avoiding the above problems.

[0056] In some technical solutions, a first target correction coefficient corresponding to the coolant temperature can be determined; when the misfire rate is less than or equal to the first preset value and the coolant temperature is within the preset temperature range, the preset maximum EGR rate is corrected using the first target correction coefficient to obtain the target EGR rate; when the misfire rate is greater than the first preset value and the coolant temperature is within the preset temperature range, the first target correction coefficient is reduced to a second target correction coefficient, and the preset maximum EGR rate is corrected using the second target correction coefficient to obtain the target EGR rate.

[0057] It is understood that the first preset value and the preset temperature range can be set according to specific circumstances. The first preset value can be 0.2%, and the preset temperature range can be 60 degrees to 90 degrees.

[0058] During the implementation process, the correction coefficient corresponding to the coolant temperature can be found from a preset mapping relationship, wherein the preset mapping relationship is used to characterize the correspondence between the coolant temperature and the correction coefficient; and the found correction coefficient is determined as the first target correction coefficient.

[0059] Among them, the preset mapping relationship can be obtained through the following steps: step-by-step adjustment of the EGR rate of the test engine at different coolant temperatures; when the combustion cycle variation of the test engine and the misfire rate of the test engine meet the first preset condition, determining the initial correction coefficient corresponding to different coolant temperatures according to the adjusted EGR rate to obtain the initial mapping relationship; performing the World Light Vehicle Test Cycle WLTC test on the test engine according to the initial mapping relationship, and adjusting the initial correction coefficient; when the combustion cycle variation of the test engine and the misfire rate of the test engine meet the second preset condition, obtaining the preset mapping relationship according to the adjusted initial correction coefficient corresponding to different coolant temperatures.

[0060] During the test, 12 representative operating points of the engine can be selected, with coolant temperatures of 60 degrees, 70 degrees, 80 degrees and 90 degrees respectively. The low-pressure EGR system is completely closed below 60 degrees.

[0061] At a coolant temperature of 60°C, a full EGR rate*K test was performed at 12 operating points, with K values ​​of 1, 0.9, 0.8, 0.7, 0.6, and 0.5, for a total of six measurement groups. A combustion analyzer was used to measure the engine's combustion cycle variation (COV) and misfire rate. After all measurements were completed, the COV and misfire rate were calculated. If COV > 4% or misfire rate > 0.1% at any operating point, the EGR rate exceeded the specified value at that temperature. For example, if the EGR rate exceeded the specified value at K values ​​of 1, 0.9, or 0.8, but did not exceed the specified value at K of 0.7, the EGR rate correction factor for that coolant temperature would be 0.7. This means that the initial correction factor for a coolant temperature of 60°C would be 0.7. Repeating these steps yielded the initial correction factors for coolant temperatures of 70°C, 80°C, and 90°C. Based on all coolant temperatures and their corresponding initial correction factors, an initial mapping relationship, such as the correction factor curve, can be generated. Based on this initial mapping, the test engine was run through four WLTC dynamic cycles, with coolant temperatures set at 60°C, 70°C, 80°C, and 90°C. If the COV measured at a particular coolant temperature exceeded 5% or the misfire rate exceeded 0.2%, the initial correction factor for that coolant temperature was reduced until the COV and misfire rate met the requirements, resulting in the target correction factor. A preset mapping was then generated based on the coolant temperature and the corresponding target correction factor.

[0062] In some technical solutions, when the misfire rate is greater than a first preset value and less than or equal to a second preset value, the first target correction coefficient may be reduced according to a preset step size until the misfire rate is less than the first preset value, and the reduced first target correction coefficient may be determined as the second target correction coefficient. When the misfire rate is greater than the second preset value, the first target correction coefficient may be directly reduced to the second target correction coefficient, where the second preset correction coefficient is equal to zero.

[0063] The second preset value and the preset step size can be set according to actual conditions. The second preset value can be 0.4%, and the actual step size can be 0.1.

[0064] It is understandable that, under normal circumstances, combustion deterioration and misfire can be avoided by correcting the EGR rate by coolant temperature. However, if the engine itself has an abnormality, such as low cylinder pressure or insufficient spark plug ignition ability, combustion deterioration can also be caused. At this time, reducing the EGR rate can also improve the combustion deterioration caused by the engine itself. Therefore, the technical solution of this application also introduces an EGR correction self-learning strategy.

[0065] During the implementation process, the EGR correction self-learning strategy can stipulate that when the misfire rate is detected to be greater than 0.2% and less than or equal to 0.4%, the coolant temperature is between 60 and 90 degrees, and the low-pressure EGR system is in the open state and lasts for 5 seconds, the first target correction coefficient can be reduced by 0.1 from the current value and run for 10 seconds until it is detected that the engine misfire rate is less than 0.2% within 5 seconds. It will no longer be updated and the reduced first target correction coefficient will be determined as the second target correction coefficient, wherein the second target correction coefficient can be reduced to 0 during this process.

[0066] When the misfire rate is greater than 0.4%, the coolant temperature is between 60 and 90 degrees, and the low-pressure EGR system is in the on state and lasts for 3 seconds, the first target correction coefficient can be directly assigned to 0, that is, the second target correction coefficient is 0.

[0067] In some technical solutions, when the misfire rate is less than a third preset value and the coolant temperature is within a preset temperature range, the preset maximum EGR rate can be corrected using the first target correction coefficient, and the corrected EGR rate is added to the preset ratio to obtain the target EGR rate; wherein the third preset value is less than the first preset value.

[0068] The third preset value and the preset ratio can be set according to actual conditions. The third preset value can be a relatively low value, such as 0.01%, and the preset ratio can be 2%.

[0069] It is understandable that if the engine burns very well when the coolant temperature is low, the EGR rate can be appropriately increased based on the product of the full EGR rate and the first target correction coefficient.

[0070] During the implementation process, when the misfire rate is detected to be less than 0.01%, the coolant temperature is between 60 and 90 degrees, and the low-pressure EGR system is in the open state and lasts for 20 seconds, 2% can be added to the EGR rate obtained by multiplying the full EGR rate by the first target correction coefficient as the target EGR rate, but the target EGR rate shall not be greater than the full EGR rate.

[0071] In some technical solutions, a preset maximum EGR rate can be used as the target EGR rate when the coolant temperature is greater than 90 degrees Celsius. By using a lower EGR rate when the coolant temperature is within the preset temperature range and the full EGR rate when the coolant temperature is greater than 90 degrees Celsius, combustion stability during the warm-up process is improved and fuel consumption is optimized.

[0072] The technical solution of this application obtains the coolant temperature in the engine cylinder and the engine misfire rate when the engine is in a warm-up state; then corrects the preset maximum EGR rate based on the coolant temperature and misfire rate to obtain a target EGR rate. By correcting the preset maximum EGR rate based on the coolant temperature and misfire rate during the engine warm-up process, the EGR rate can be reduced, not only maximizing the EGR rate but also reducing the probability of engine misfires, thereby providing the engine with the maximum protection possible.

[0073] The following describes the device technical solution of this application, which can be used to implement the EGR rate control method in the above technical solution of this application. For details not disclosed in the device technical solution of this application, please refer to the technical solution of the EGR rate control method in the above technical solution of this application.

[0074] Refer to FIG3 , which shows a block diagram of the EGR rate control device in the technical solution of the present application.

[0075] As shown in Figure 3, the EGR rate control device of the technical solution of the present application includes: a data acquisition module 301 and an EGR rate correction module 302, wherein the data acquisition module 301 is used to obtain the coolant temperature in the engine cylinder and the misfire rate of the engine when the engine is in a warm-up state; the EGR rate correction module 302 is used to correct the preset maximum EGR rate according to the coolant temperature and the misfire rate to obtain the target EGR rate.

[0076] In some technical solutions of the present application, based on the aforementioned solution, the EGR rate correction module 302 is further used to determine a first target correction coefficient corresponding to the coolant temperature; when the misfire rate is less than or equal to the first preset value and the coolant temperature is within the preset temperature range, the preset maximum EGR rate is corrected using the first target correction coefficient to obtain the target EGR rate; when the misfire rate is greater than the first preset value and the coolant temperature is within the preset temperature range, the first target correction coefficient is reduced to a second target correction coefficient, and the preset maximum EGR rate is corrected using the second target correction coefficient to obtain the target EGR rate.

[0077] In some technical solutions of the present application, based on the aforementioned solution, the EGR rate correction module 302 is also used to find the target correction coefficient corresponding to the coolant temperature from a preset mapping relationship, wherein the preset mapping relationship is used to characterize the correspondence between the coolant temperature and the target correction coefficient; and the found target correction coefficient is determined as the first target correction coefficient.

[0078] In some technical solutions of the present application, based on the aforementioned solution, the EGR rate correction module 302 is also used to perform step-by-step adjustments to the EGR rate of the test engine at different coolant temperatures; when the combustion cycle variation of the test engine and the misfire rate of the test engine meet a first preset condition, the initial correction coefficient corresponding to the different coolant temperatures is determined according to the adjusted EGR rate to obtain an initial mapping relationship; the test engine is subjected to a World Light Vehicle Test Cycle WLTC test according to the initial mapping relationship, and the initial correction coefficient is adjusted; when the combustion cycle variation of the test engine and the misfire rate of the test engine meet a second preset condition, the preset mapping relationship is obtained according to the adjusted initial correction coefficient corresponding to the different coolant temperatures.

[0079] In some technical solutions of the present application, based on the aforementioned solution, the EGR rate correction module 302 is further used to reduce the first target correction coefficient according to a preset step size when the misfire rate is greater than the first preset value and less than or equal to the second preset value, until the misfire rate is less than the first preset value, and determine the reduced first target correction coefficient as the second target correction coefficient.

[0080] In some technical solutions of the present application, based on the aforementioned solution, the EGR rate correction module 302 is further configured to directly reduce the first target correction coefficient to a second target correction coefficient when the misfire rate is greater than a second preset value, wherein the second preset correction coefficient is equal to zero.

[0081] In some technical solutions of the present application, based on the aforementioned solution, the EGR rate correction module 302 is also used to correct the preset maximum EGR rate using the first target correction coefficient when the misfire rate is less than a third preset value and the coolant temperature is within a preset temperature range, and add the corrected EGR rate to the preset ratio to obtain the target EGR rate; wherein the third preset value is less than the first preset value.

[0082] Based on the same application concept, the technical solution of the present application also provides an EGR rate control device. Referring to Figure 4, Figure 4 shows a structural schematic diagram of the EGR rate control device in the technical solution of the present application. The EGR rate control device includes one or more memories 404, one or more processors 402 and at least one computer program (computer program instruction) stored on the memory 404 and executable on the processor 402. When the processor 402 executes the computer program, the method described above is implemented.

[0083] In FIG4 , a bus architecture (represented by bus 400) is shown. Bus 400 may include any number of interconnected buses and bridges. Bus 400 links various circuits together, including one or more processors represented by processor 402 and memory represented by memory 404. Bus 400 may also link various other circuits together, such as peripherals, voltage regulators, and power management circuits, all of which are well known in the art and, therefore, will not be described further herein. Bus interface 405 provides an interface between bus 400 and receiver 401 and transmitter 403. Receiver 401 and transmitter 403 may be the same component, namely a transceiver, providing a unit for communicating with various other devices over a transmission medium. Processor 402 is responsible for managing bus 400 and general processing, while memory 404 may be used to store data used by processor 402 when performing operations.

[0084] Based on the same application concept, the technical solution of this application provides a computer-readable storage medium, in which computer program instructions are stored. When the computer program instructions are executed by a processor, the processor is prompted to implement the steps of the method as described above.

[0085] The functions described herein may be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions may be stored as one or more instructions or codes on or transmitted via a computer-readable medium. Other examples and implementations are within the scope and spirit of this application and the appended claims. For example, due to the nature of software, the functions described above may be implemented using software executed by a processor, hardware, firmware, hardwiring, or a combination of any of these. Furthermore, the functional units may be integrated into a single processing unit, each unit may exist physically separately, or two or more units may be integrated into a single unit.

[0086] In the several technical solutions provided in this application, it should be understood that the disclosed technical content can be implemented in other ways. Among them, the device technical solutions described above are only schematic. For example, the division of the units can be a logical function division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of units or modules, which can be electrical or other forms.

[0087] The units described as separate components may or may not be physically separate, and the components of the control device may or may not be physical units, that is, they may be located in one place or distributed across multiple units. Some or all of the units may be selected according to actual needs to achieve the purpose of the present technical solution.

[0088] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes a number of instructions for enabling a computer device (which can be a personal computer, server or network device, etc.) to execute all or part of the steps of the method described in each technical solution of the present application. The aforementioned storage medium includes: U disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), mobile hard disk, magnetic disk or optical disk, and other media that can store computer program instructions.

[0089] The above description is merely the technical solution of this application and is not intended to limit this application. Those skilled in the art will readily appreciate that this application is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this application shall be within the scope of the claims of this application.

Claims

1. An EGR rate control method, applied to a low-pressure EGR system, characterized in that: include: When the engine is in a warm-up state, obtaining a coolant temperature in a cylinder of the engine and a misfire rate of the engine; The preset maximum EGR rate is corrected according to the coolant temperature and the misfire rate to obtain a target EGR rate.

2. The EGR rate control method according to claim 1, characterized in that: The step of correcting the preset maximum EGR rate according to the coolant temperature and the misfire rate to obtain a target EGR rate includes: determining a first target correction coefficient corresponding to the coolant temperature; When the misfire rate is less than or equal to a first preset value and the coolant temperature is within a preset temperature range, the preset maximum EGR rate is corrected using the first target correction coefficient to obtain the target EGR rate; When the misfire rate is greater than the first preset value and the coolant temperature is within a preset temperature range, the first target correction coefficient is reduced to a second target correction coefficient, and the preset maximum EGR rate is corrected using the second target correction coefficient to obtain the target EGR rate.

3. The EGR rate control method according to claim 2, characterized in that: The determining of the first target correction coefficient corresponding to the coolant temperature includes: searching a target correction coefficient corresponding to the coolant temperature from a preset mapping relationship, wherein the preset mapping relationship is used to represent a correspondence between the coolant temperature and the target correction coefficient; The found target correction coefficient is determined as the first target correction coefficient.

4. The EGR rate control method according to claim 3, characterized in that: Also includes: The EGR rate of the test engine was adjusted in steps at different coolant temperatures; When the combustion cycle variation of the test engine and the misfire rate of the test engine meet a first preset condition, determining an initial correction coefficient corresponding to different coolant temperatures according to the adjusted EGR rate to obtain an initial mapping relationship; Performing a World Light Vehicle Test Cycle (WLTC) test on the test engine according to the initial mapping relationship, and adjusting the initial correction coefficient; When the combustion cycle variation of the test engine and the misfire rate of the test engine meet a second preset condition, the preset mapping relationship is obtained according to the adjusted initial correction coefficients corresponding to different coolant temperatures.

5. The EGR rate control method according to claim 2, characterized in that: When the misfire rate is greater than the first preset value, reducing the first target correction coefficient to a second target correction coefficient includes: When the misfire rate is greater than the first preset value and less than or equal to a second preset value, the first target correction coefficient is reduced according to a preset step size until the misfire rate is less than the first preset value, and the reduced first target correction coefficient is determined as the second target correction coefficient.

6. The EGR rate control method according to claim 2, characterized in that: When the misfire rate is greater than the first preset value, reducing the first target correction coefficient to a second target correction coefficient includes: When the misfire rate is greater than the second preset value, the first target correction coefficient is directly reduced to a second target correction coefficient, wherein the second preset correction coefficient is equal to zero.

7. The EGR rate control method according to claim 2, characterized in that: Also includes: When the misfire rate is less than a third preset value and the coolant temperature is within a preset temperature range, the preset maximum EGR rate is corrected using the first target correction coefficient, and the corrected EGR rate is added to a preset ratio to obtain the target EGR rate; wherein the third preset value is less than the first preset value.

8. An EGR rate control device, applied to a low-pressure EGR system, characterized in that: include: a data acquisition module, configured to acquire a coolant temperature in a cylinder of the engine and a misfire rate of the engine when the engine is in a warm-up state; The EGR rate correction module is used to correct the preset maximum EGR rate according to the coolant temperature and the misfire rate to obtain a target EGR rate.

9. An EGR rate control device, comprising a processor and a memory, characterized in that: The memory stores computer program instructions that can be executed by the processor, and when the processor executes the computer program instructions, the steps of the method according to any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium, characterized in that The computer-readable storage medium stores computer program instructions, which, when executed by a processor, prompt the processor to implement the steps of the method according to any one of claims 1 to 7.

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