Pre- and post-processing methods for the feedback control phase of the mixing valve in a low-pressure EGR system

Abstract

The present invention relates to a pre- and post-processing method for a low-pressure EGR system mixing valve feedback control phase. The pre-processing method comprises: after the vehicle is powered on, determining whether the ambient temperature presents a risk of condensation and icing; if so, directly entering the mixing valve feedback control phase; if not, determining whether the mixing valve needs to be cleaned; if not, directly entering the mixing valve feedback control phase; if cleaning is required, executing a purge operation; and, after successful cleaning, entering the mixing valve feedback control phase. The post-processing method comprises: after the vehicle is powered off, determining whether the mixing valve needs to be cleaned; if so, executing a purge operation. The present invention can maintain the cleanliness of the valve body before the mixing valve feedback control phase, eliminating interference from the valve body cleanliness on the entire mixing valve feedback control phase.

Description

Technical Field

[0001] The present invention relates to an exhaust gas recirculation system, and more particularly to a method for processing before and after a feedback control phase of a mixing valve of a low-pressure EGR system. Background Art

[0002] The use of an EGR system (exhaust gas recirculation) primarily reduces nitrogen oxide emissions. By reintroducing exhaust gas into the cylinder, a higher proportion of inert gas is mixed into the combustible gas within the cylinder, slowing combustion and reducing engine knock. This also increases the specific heat capacity of the mixture, lowering the cylinder temperature during combustion. Since high temperature and oxygen enrichment are the primary conditions for the formation of nitrogen oxides, lowering cylinder temperature reduces nitrogen oxide emissions.

[0003] Compared to traditional high-pressure EGR systems, low-pressure EGR systems can significantly reduce nitrogen oxide emissions and reduce engine fuel consumption. However, due to the longer exhaust gas recirculation path, low-pressure EGR systems may result in insufficient intake pressure for exhaust gas to enter the cylinders. Therefore, a mixing valve is required in the low-pressure EGR system. By controlling the opening of the mixing valve, the pressure behind the mixing valve is adjusted, allowing exhaust gas to be drawn into the cylinders.

[0004] Prior art methods for controlling mixing valves require accurate parameters of the controlled valve hardware before ensuring precise control. However, due to varying process control capabilities among hardware suppliers, individual product dimensions and other parameters may vary. Controlling the valve body based on default parameters is clearly inaccurate. Furthermore, valve cleanliness can interfere with the overall control method, and existing control methods are unable to eliminate this interference. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a pre- and post-processing method for the mixing valve feedback control stage of a low-pressure EGR system, which can maintain the cleanliness of the valve body before the mixing valve feedback control stage and eliminate the interference of the cleanliness of the valve body on the entire mixing valve feedback control stage.

[0006] The technical solution adopted by the present invention to solve the technical problem is: constructing a pre- and post-processing method of a mixing valve feedback control stage of a low-pressure EGR system, characterized by comprising a pre-processing stage located before the mixing valve feedback control stage and a post-processing stage located after the mixing valve feedback control stage;

[0007] The processing methods in the pre-processing stage include:

[0008] After the vehicle is powered on, it determines whether the ambient temperature poses a risk of condensation and icing. If so, the system directly enters the mixing valve feedback control phase. If not, it determines whether the mixing valve needs to be cleaned. If not, the system directly enters the mixing valve feedback control phase. If cleaning is required, the system performs the cleaning operation, and if the cleaning operation is successful, the system enters the mixing valve feedback control phase.

[0009] The post-processing methods include:

[0010] After the vehicle is powered off, it is determined whether the mixing valve needs to be cleaned. If the mixing valve needs to be cleaned, the cleaning action is performed.

[0011] According to the above scheme, when the vehicle is powered on for the first time, the pre-processing stage also includes the following processing methods:

[0012] First determine whether the current mixing valve has undergone initial position learning. If it has not, position learning needs to be performed. If the learning is successful, the maximum and minimum positions learned will be stored. If the learning fails, a fault code will be reported and the EGR system will be prohibited from working.

[0013] According to the above scheme, before the step of determining whether the mixing valve needs to be cleaned is performed in the pre-processing stage and the post-processing stage, the following steps are further included:

[0014] It is determined whether the current actual number of driving cycles of the vehicle reaches the specified number of driving cycles. If the number of driving cycles is less than the specified number of driving cycles, it is directly determined that cleaning is not required. If the number of driving cycles is not less than the specified number of driving cycles, the step of determining whether cleaning the mixing valve is required is executed.

[0015] According to the above scheme, in the post-processing stage, if the number of driving cycles is not less than the specified number of driving cycles, if the mixing valve needs to be cleaned, the position learning action of the mixing valve is performed after the cleaning action is completed; if the mixing valve does not need to be cleaned, the position learning action of the mixing valve is directly performed; if the cleaning action fails, a fault code is reported, and the EGR system is prohibited from working the next time it needs to work.

[0016] According to the above scheme, whether the mixing valve needs to be cleaned is determined through maximum position sensing and minimum position sensing in the pre-processing stage and the post-processing stage.

[0017] According to the above scheme, the method for maximum position awareness includes:

[0018] When entering the maximum position awareness phase, the total time of the maximum position awareness phase begins to accumulate;

[0019] Provide the mixing valve motor with a calibrated maximum position opening that needs to be sensed, so that the valve body of the mixing valve moves toward the maximum position;

[0020] If the absolute position is greater than 99%, or the actual relative opening of the mixing valve is greater than 95%, the stabilization time for sensing the maximum position begins to accumulate;

[0021] When the stabilization time for sensing the maximum position is greater than the standard stabilization time, the maximum position sensing is considered to be completed and the minimum position sensing phase is entered; otherwise, the maximum position sensing phase continues;

[0022] When the total time of the maximum position sensing stage is greater than the total time of the standard sensing stage, it is considered that the maximum sensing has timed out and the sensing has failed, and it is determined that the mixing valve needs to be cleaned.

[0023] According to the above scheme, the minimum location awareness method includes:

[0024] When entering the minimum position awareness phase, the total time of the minimum position awareness phase begins to accumulate;

[0025] Provide the mixing valve motor with a calibratable default minimum position opening, so that the valve body of the mixing valve moves toward the minimum position;

[0026] If the absolute position is less than 3% or the actual relative opening of the mixing valve is less than 1%, the stabilization time for sensing the minimum position starts to accumulate;

[0027] When the stabilization time for sensing the minimum position is greater than the standard stabilization time, the minimum position sensing is considered to be completed and the sensing is considered successful; otherwise, the minimum position sensing is continued;

[0028] When the total time of the minimum position sensing stage is greater than the total time of the standard sensing stage, it is considered that the minimum sensing has timed out and the sensing has failed, and it is determined that the mixing valve needs to be cleaned.

[0029] According to the above scheme, in the pre-processing stage and the post-processing stage, the maximum position cleaning control method in the cleaning action control method includes:

[0030] After entering the maximum position cleaning phase, the total time of the maximum position cleaning phase begins to accumulate;

[0031] Give the mixing valve motor an opening for maximum position cleaning, so that the valve body of the mixing valve moves toward the maximum position to perform valve flushing cleaning;

[0032] If the absolute position is greater than 99%, or the actual relative opening of the mixing valve is greater than 95%, the stabilization time for cleaning the maximum position begins to accumulate;

[0033] When the stabilization time for cleaning the maximum position is greater than the standard stabilization time, the maximum position cleaning is considered completed and the minimum position cleaning phase is entered, and the maximum position cleaning failure flag is set to false. Otherwise, the maximum position cleaning continues.

[0034] When the total time of the maximum cleaning phase is greater than the total time of the standard cleaning phase, it is considered that the maximum position cleaning has failed, and the maximum position cleaning failure flag is set to true.

[0035] According to the above scheme, in the pre-processing stage and the post-processing stage, the minimum position cleaning control method in the cleaning action control method includes:

[0036] After entering the minimum position cleaning phase, the total time of the minimum cleaning phase begins to accumulate;

[0037] Give the mixing valve motor an opening for minimum position cleaning, so that the valve body of the mixing valve moves toward the minimum position to perform valve flushing cleaning;

[0038] If the absolute position is less than 3%, or the actual relative opening of the mixing valve is less than 1%, the stabilization time for cleaning the minimum position starts to accumulate;

[0039] When the stabilization time for cleaning the minimum position is greater than the standard stabilization time, the minimum position cleaning is considered completed, and the minimum position cleaning failure flag is set to false. Otherwise, the minimum position cleaning continues.

[0040] When the total time of the minimum cleaning phase is greater than the total time of the standard cleaning phase, it is considered that the minimum position cleaning has failed, and the minimum position cleaning failure flag is set to true.

[0041] The present invention also provides a computer-readable storage medium having executable instructions stored thereon, characterized in that when the instructions are executed by a processor, the processor implements the steps of the pre- and post-processing method of the low-pressure EGR system mixing valve feedback control stage.

[0042] The implementation of the pre- and post-processing method of the low-pressure EGR system mixing valve feedback control stage of the present invention has the following beneficial effects:

[0043] 1. The pre-processing cleaning action of the present invention ensures the accuracy of the mixing valve in the feedback control link. The post-processing cleaning strategy ensures the cleanliness of the mixing valve body before position learning, thereby ensuring the accuracy of the position learning parameters.

[0044] 2. This invention takes ambient temperature into consideration, avoiding potential damage to the supercharger caused by pre- and post-processing actions. For example, on a winter morning, there may be frozen dew on the valve body. If the valve body moves at this time, ice fragments will be blown into the supercharger, causing irreversible damage to the supercharger.

[0045] 3. Through the post-processing learning strategy after power-off, it is possible to avoid errors caused by hardware production process or dimensional errors caused by wear and tear, which may cause inaccurate feedback control of the mixing valve next time. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which:

[0047] Figure 1 It is a schematic diagram of the pre- and post-processing method of the low-pressure EGR system mixing valve feedback control stage of the present invention;

[0048] Figure 2 It is a flow chart of the pre- and post-processing method of the low-pressure EGR system mixing valve feedback control stage of the present invention. DETAILED DESCRIPTION

[0049] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, specific embodiments of the present invention are now described in detail with reference to the accompanying drawings.

[0050] like Figure 1-2 As shown, the pre- and post-processing methods for the mixing valve feedback control phase of a low-pressure EGR system of the present invention include a pre-processing method S1 located before the mixing valve feedback control phase and a post-processing method S2 located after the mixing valve feedback control phase. The control method for the mixing valve feedback control phase belongs to the prior art.

[0051] The processing method S1 of the pre-processing stage includes the following steps:

[0052] After the vehicle is powered on, it is determined whether the ambient temperature poses a risk of condensation and icing; if so, the system directly enters the mixing valve feedback control stage; if not, it is determined whether the mixing valve needs to be cleaned; if not, the system directly enters the mixing valve feedback control stage; if the mixing valve needs to be cleaned, the cleaning action is performed, and after the cleaning action is successful, the system enters the mixing valve feedback control stage.

[0053] The post-processing method S2 includes the following steps:

[0054] After the vehicle is powered off, it is determined whether the mixing valve needs to be cleaned. If the mixing valve needs to be cleaned, the cleaning action is performed.

[0055] Preferably, the specific steps of the processing method S1 in the pre-processing stage are as follows:

[0056] S101: When determining whether the ambient temperature has the risk of condensation and freezing, it is first necessary to determine the ambient temperature T at that time. ambient If the ambient temperature T ambient >Enable temperature T safe+, then execute the following pre-processing strategy. If the ambient temperature T ambient <Exit enable temperature T safe- , the pre-treatment strategy is not executed. The purpose of the pre-treatment strategy is to ensure the cleanliness of the valve body and ensure that the feedback control of the mixing valve is more accurate when the EGR system is working. Set T safe+ and T safe- This is to avoid the pre-processing strategy from suddenly exiting when the ambient temperature fluctuates slightly in a short period of time. Therefore, it is necessary to set a hysteresis judgment for the ambient temperature trigger condition. safe+ Generally set to 3℃, T safe- It is usually set to 0℃.

[0057] However, the premise of executing the pre-processing action is to ensure the stability and safety of the EGR system. ambient <T safe+ When the temperature is too low, there may be condensed ice debris on the valve body. If the valve body moves at this time, the hard ice debris may be swept into the supercharger, causing damage to the supercharger. Therefore, if the temperature conditions are not met, the feedback control pre-processing will not be executed and the mixing valve feedback control stage will be directly entered.

[0058] S102: When the vehicle is powered on for the first time, the first step is to determine whether the mixing valve has undergone initial position learning based on whether the FirstLearnDone flag is set to 1. This determination is performed after the production of a new vehicle to ensure that the controller has confirmed the actual maximum and minimum position parameters of the mixing valve body before the first operation of the EGR system. This is used for subsequent precise control of the mixing valve.

[0059] If FirstLearnDone is not set to 1, it means that the first position learning has not yet been completed and position learning needs to be performed. If the learning action is successful, the maximum and minimum positions learned are stored and FirstLearnDone is set to 1. If the learning fails, a fault code is reported. After the code is reported, the EGR system is disabled.

[0060] If FirstLearnDone is set to 1, first determine the actual number of driving cycles N of the vehicle circycle Whether the specified number of driving cycles N is reached CircycleCriterion If the number of driving cycles N circycle <Specified number of driving cycles N CircycleCriterion , no pre-processing action is performed. If N circycle = N CircycleCriterion , then perform perception action.

[0061] The benefits of the driving cycle judgment strategy are as follows: 1. The valve body's sensing action is noisy, and reducing the sensing action can improve the user's driving experience. 2. Reducing the frequency of sensing actions can slightly reduce energy consumption and increase the life of the valve body. Based on the actual working conditions of the engine, after how many driving cycles the valve body is not clean enough, the corresponding designated number of driving cycles N can be set. CircycleCriterion .

[0062] S103, when the valve body control enters the sensing action stage. The purpose of the sensing action is to detect whether the current valve body is clean enough. If the sensing action is successful, there is no need to perform the cleaning action and directly enter the mixing valve feedback control link. If the sensing action fails, a cleaning action needs to be performed. The required duty cycle of the cleaning action is relatively large, and the number of executions is relatively large, so it will also cause correspondingly large noise and damage to the valve body and motor. Adding sensing action to the pre-processing strategy can minimize the number of times the cleaning action needs to be performed. It can improve the life of the valve body and the NVH of the passenger compartment.

[0063] S104: When the valve body control enters the cleaning action phase, if the cleaning action is successful, the mixing valve feedback control phase is entered. If the cleaning action fails, a fault code is reported and the EGR system is disabled.

[0064] Preferably, the post-processing method S2 further comprises the following steps:

[0065] S201: After powering off, first determine the actual number of driving cycles N of the vehicle. circycle Whether the specified number of driving cycles N is reached CircycleCriterion If the number of driving cycles N circycle <Number of driving cycles specified CircycleCriterion , no post-processing action is performed. If the number of driving cycles N circycle = Specified number of driving cycles N CircycleCriterion , then perform perception action.

[0066] S202: The vehicle is powered off and the valve control enters the sensing phase. If the sensing phase succeeds, the position learning phase begins. If the sensing phase fails, a cleaning phase is performed.

[0067] S203: When the valve body control enters the cleaning phase, if the cleaning is successful, the position learning phase is entered. If the cleaning fails, a fault code is reported and the EGR system is prohibited from operating the next time it is required.

[0068] S204, Position Learning. After a certain number of driving cycles, the mixing valve and spring may wear out, so the maximum and minimum positions need to be relearned to ensure accuracy during the feedback control phase. If the valve position was not learned during the pre-processing strategy stage, this learning phase not only stores the learned position data but also sets FirstLearnDone from 0 to 1. If the position learning fails, a fault code will be reported, and the EGR system will be disabled until the fault code is cleared.

[0069] Preferably, the calculation algorithm of the driving cycle is as follows:

[0070] When the vehicle is in the power-off state, the power-off state flag bit PowerOff=true, otherwise PowerOff=false.

[0071] When the engine is in the shutdown state, the engine shutdown state flag EngineOff=true, otherwise EngineOff=false.

[0072] When the ambient temperature T ambient >Enable temperature T safe+ When the temperature flag TempOK=true; when the ambient temperature T ambient <Exit enable temperature T safe- When the temperature is set to 0, the temperature flag TempOK=false.

[0073] ValvePreEnable=Poweroff&EngineOff&TempOK

[0074] ValvePreEnable represents the pre-enable flag bit when the working conditions of the mixing valve are met.

[0075] Whenever ValvePreEnable changes from false to true, N circycle (N) = N circycle (N-1)+1; otherwise N circycle (N) = N circycle (N-1).

[0076] When N circycle (N-1)>N CircycleCriterion When N circycle (N) = 1. The number of driving cycles is reset.

[0077] Among them, N circycle (N) is the number of driving cycles in control period N, N circycle (N-1) is the number of driving cycles during control period N-1, N CircycleCriterion The number of driving cycles specified.

[0078] Preferably, in the pre-processing stage and the post-processing stage, whether the mixing valve needs to be cleaned is determined by sensing the maximum position and the minimum position. The maximum position sensing method includes:

[0079] When entering the maximum position perception stage, T sum_sense_Max Start cumulative timing.

[0080] T sum_sense_Max (N+1) = T sum_sense_Max (N)+T

[0081] Give the motor a calibrated maximum position opening P that needs to be sensed SensActMax .

[0082] The duty cycle of the mixing valve motor is calculated and controlled based on the PID algorithm to move the valve body of the mixing valve toward the maximum position. The discrete PID algorithm is generally used in industry. The specific formula is as follows:

[0083] e open (N) = P SensActMax (N)− P open (N)

[0084] Points section:

[0085]

[0086] Differentiation link:

[0087]

[0088] Duty cycle:

[0089]

[0090] If S SensePos >99%, or P open >95%, T stabletime_Maxsense Start accumulating time. stabletime_Maxsense (N+1) = T stabletime_Maxsense (N)+T.

[0091] During the timing phase, if S SensePos ≤99%, and P open ≤95%, then T stabletime_Maxsense Cleared. Until S SensePos >99%, or P open >95%, T stabletime_Maxsense Start to accumulate time again, T stabletime_Maxsense Return to zero. Among them, P open = .

[0092] When T stabletime_Maxsense >T stabletime_criteria When T is reached, the maximum position sensing is considered to be completed and the minimum position sensing phase is entered. Otherwise, the maximum position sensing phase is continued. sum_sense_Max >T sum_sense_criteria When the maximum perception timeout is reached, the perception fails.

[0093] Minimally location-aware methods include:

[0094] When entering the minimum position perception stage, T sum_sense_Min Start cumulative timing.

[0095] T sum_sense_Min (N+1) = T sum_sense_Min (N)+T

[0096] Give the motor a calibrable default minimum position opening P SensActMin , calculate and control the duty cycle of the mixing valve motor based on the PID algorithm to move the valve body of the mixing valve toward the minimum position. The specific formula is as follows:

[0097] Discretization

[0098] e open (N) = P SensActMin (N)− P open (N)

[0099] Points section:

[0100]

[0101] Differentiation link:

[0102]

[0103] Duty cycle:

[0104]

[0105] If S SensePos <3% or P open <1%, T stabletime_Minsense Start accumulating timing. During the timing phase, if S SensePos ≥3%, and P open ≥ 1%, then T stabletime_Minsense Clear. S SensePos <3% and P open <1%, T stabletime_Minsense Start accumulating time again.

[0106] T stabletime_Minsense (N+1) = T stabletime_Minsense (N)+T, when T stabletime_Minsense >Tstabletime_criteria When T is reached, the minimum position perception is considered to be completed and the perception is considered successful. Otherwise, the minimum position perception is continued. sum_sense_Min >T sum_sense_criteria When the minimum perception timeout is reached, the perception fails.

[0107] If the perception is successful, the position learning phase can be entered directly. If the perception fails, it means that the valve body is not clean or is stuck, and the cleaning phase needs to be entered.

[0108] The formula parameters involved in the above are explained as follows:

[0109] T: Control cycle

[0110] P SensActMin :Default for minimum position sensing opening

[0111] P SensActMax :Default opening for maximum position awareness

[0112] S SensePos : Absolute position measured by the position sensor

[0113] S Learn_Min : The minimum absolute position measured by position learning

[0114] S Learn_Max : The maximum absolute position measured by position learning

[0115] P open : The actual relative opening of the mixing valve

[0116] T stabletime_Minsense : The stabilization time for sensing the minimum position

[0117] T stabletime_Maxsense : The stabilization time for sensing the maximum position

[0118] T stabletime_criteria : Standard stabilization time, the default setting is 0.5s

[0119] T sum_sense_Min : Total time of the minimum position awareness phase

[0120] T sum_sense_Max : Total time of the maximum position awareness phase

[0121] T sum_sense_criteria : The total time of the standard perception phase, the default setting is 4s

[0122] η duty : Duty cycle of the motor.

[0123] Preferably, in the pre-processing stage and the post-processing stage, the maximum position cleaning control method in the cleaning action control method includes:

[0124] When entering the maximum position sweeping stage, T sum_clean_Max Start accumulating time, T sum_clean_Max (N+1) =T sum_clean_Max (N)+T.

[0125] Give the motor a calibrated maximum position opening P that needs to be cleaned CleanActMax The duty cycle of the mixing valve motor is calculated and controlled based on the PID algorithm, so that the valve body of the mixing valve moves toward the maximum position to perform valve flushing and cleaning. Discrete PID algorithm is generally used in industry:

[0126] e open (N) = P CleanActMax (N)− P open (N)

[0127] Points section:

[0128]

[0129] Differentiation link:

[0130]

[0131] Duty cycle:

[0132]

[0133] If S CleanPos >99%, or P open >95%, T stabletime_Maxclean Start accumulating time, T stabletime_Maxclean (N+1) = T stabletime_Maxclean (N)+T. Among them, P open = .

[0134] During the timing phase, if S CleanPos ≤99%, and P open ≤ 95%, then T stabletime_Maxclean Cleared. Until S CleanPos >99%, or P open >95%, T stabletime_Maxclean Start to accumulate time again, T stabletime_Maxclean Reset to zero.

[0135] When T stabletime_Maxclean >T stabletime_criteriaWhen the maximum position cleaning is completed, it is considered that the minimum position cleaning phase has been entered, and the maximum position cleaning failure flag MaxCleanFailed is set to false. Otherwise, the maximum position cleaning continues.

[0136] When T sum_clean_Max >T sum_clean_criteria When the maximum position cleaning fails, it is considered that the maximum position cleaning has failed. The maximum position cleaning failure flag MaxCleanFailed is set to true.

[0137] The methods for minimum position sweep control include:

[0138] When entering the minimum position cleaning stage, T sum_clean_Min Start accumulating time, T sum_clean_Min (N+1) =T sum_clean_Min (N)+T.

[0139] Give the motor a calibrable default minimum position opening P CleanActMin , calculate and control the duty cycle of the mixing valve motor based on the PID algorithm, so that the valve body of the mixing valve moves toward the minimum position to perform valve flushing and cleaning. The algorithm is as follows:

[0140] Discretization

[0141] e open (N) = P CleanActMin (N)− P open (N)

[0142] Points section:

[0143]

[0144] Differentiation link:

[0145]

[0146] Duty cycle:

[0147]

[0148] If S CleanPos <3% or P open <1%, T stabletime_Minclean Start accumulating timing. During the timing phase, if S CleanPos ≥3%, and P open ≥1%, then T stabletime_Minclean Clear. S CleanPos <3% and P open <1%, T stabletime_Minclean Start accumulating time again. stabletime_Minclean (N+1) = T stabletime_Minclean (N)+T.

[0149] When T stabletime_Minclean >T stabletime_criteria When the minimum position cleaning is completed, it is considered that the cleaning is successful, and MinCleanFailed is set to false. Otherwise, the minimum position cleaning continues.

[0150] When T sum_clean_Min >T sum_clean_criteria When the minimum position cleaning fails, it is considered that the minimum position cleaning has failed. The minimum position cleaning failure flag MinCleanFailed is set to true.

[0151] if MaxCleanFailed || MinCleanFailed = true, n CleanFailed (N) = n CleanFailed (N-1)+1. If n CleanFailed (N)>2, it is considered that the valve body of the mixing valve is stuck and cannot be successfully cleaned, and then a fault code is reported and the EGR system is prohibited from working. CleanFailed If (N)≤2, the cleaning action will be restarted from the maximum position. The purpose is to limit the cleaning action to a maximum of 3 times.

[0152] When the fault code is cleared, n CleanFailed If MaxCleanFailed || MinCleanFailed = false, the cleaning action is considered successful and the learning phase can begin.

[0153] The formula parameters involved in the above are explained as follows:

[0154] T: Control cycle

[0155] P CleanActMin :Default for minimum position cleaning opening

[0156] P CleanActMax :Default opening for maximum position sweeping

[0157] S CleanPos : Absolute position measured by the position sensor

[0158] S Learn_Min : The minimum absolute position measured by position learning

[0159] S Learn_Max : The maximum absolute position measured by position learning

[0160] P open : The actual relative opening of the mixing valve

[0161] T stabletime_Minclean : Stabilization time for cleaning the minimum position

[0162] T stabletime_Maxclean : Stabilization time for sweeping maximum position

[0163] T stabletime_criteria : Standard stabilization time, the default setting is 0.5s

[0164] T sum_clean_Min : Total time of the minimum sweeping phase

[0165] T sum_clean_Max : Total time of the maximum sweeping phase

[0166] T sum_clean_criteria : The total time of the standard cleaning phase, the default setting is 4s

[0167] η duty : Duty cycle of the motor

[0168] MaxCleanFailed: Maximum position cleaning failure flag

[0169] MinCleanFailed: minimum position cleaning failure flag

[0170] n CleanFailed : Number of cleaning failures, the initial value is set to 0.

[0171] The advantages of the pre- and post-processing method of the low-pressure EGR system mixing valve feedback control stage of the present invention are as follows:

[0172] 1. The post-processing learning strategy after power-off can prevent inaccurate feedback control of the mixing valve during the next cycle due to errors caused by the hardware production process or dimensional errors caused by wear and tear. 2. The post-processing cleaning strategy ensures the cleanliness of the mixing valve body before position learning, thereby ensuring the accuracy of the position learning parameters. 3. The perception strategy in pre- and post-processing improves the NVH of the pre- and post-processing actions, enhancing the user experience. 4. Both the pre- and post-processing strategies are designed with reasonable trigger logic, extending the service life of the valve body, improving NVH, and enhancing the user experience. 5. The pre-processing cleaning action ensures the accuracy of the mixing valve in the feedback control link. 6. Due to the special layout of the mixing valve, which is placed before the supercharger, the present invention takes into account the ambient temperature factor and avoids potential damage to the supercharger caused by pre- and post-processing actions. For example, on a winter morning, there may be frozen dew on the valve body. If the valve body moves at this time, crushed ice will be driven into the supercharger, causing irreversible damage to the supercharger.

[0173] Example 2

[0174] The present invention also provides a computer-readable storage medium having executable instructions stored thereon. When the instructions are executed by a processor, the processor implements the pre- and post-processing method of the low-pressure EGR system mixing valve feedback control stage.

[0175] Example 3

[0176] The present invention also provides an electronic device, comprising: a processor, a communication interface, a memory and a communication bus, wherein the processor, the communication interface and the memory communicate with each other through the communication bus; a computer program is stored in the memory, and when the program is executed by the processor, the processor executes the steps of the pre- and post-processing method of the low-pressure EGR system mixing valve feedback control stage.

[0177] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware. Furthermore, the present application may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0178] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0179] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0180] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0181] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the present invention and the claims, all of which are protected by the present invention.

Claims

1. A method for pre- and post-processing of a low-pressure EGR system mixing valve feedback control phase, characterized in that: It includes a pre-processing stage located before the mixing valve feedback control stage and a post-processing stage located after the mixing valve feedback control stage; The processing methods in the pre-processing stage include: After the vehicle is powered on, it determines whether the ambient temperature poses a risk of condensation and icing. If so, the system directly enters the mixing valve feedback control phase. If not, it determines whether the mixing valve needs to be cleaned. If not, the system directly enters the mixing valve feedback control phase. If cleaning is required, the system performs the cleaning operation, and if the cleaning operation is successful, the system enters the mixing valve feedback control phase. The post-processing methods include: After the vehicle is powered off, it is determined whether the mixing valve needs to be cleaned. If the mixing valve needs to be cleaned, the cleaning action is performed.

2. The method for pre- and post-processing of the low-pressure EGR system mixing valve feedback control phase according to claim 1, characterized in that: When the vehicle is powered on for the first time, the pre-processing stage also includes: First determine whether the current mixing valve has undergone initial position learning. If it has not, position learning needs to be performed. If the learning is successful, the maximum and minimum positions learned will be stored. If the learning fails, a fault code will be reported and the EGR system will be prohibited from working.

3. The method for pre- and post-processing of the low-pressure EGR system mixing valve feedback control phase according to claim 1, characterized in that: Before the pre-processing stage and the post-processing stage perform the step of determining whether the mixing valve needs to be cleaned, the following steps are also included: It is determined whether the current actual number of driving cycles of the vehicle reaches the specified number of driving cycles. If the number of driving cycles is less than the specified number of driving cycles, it is directly determined that cleaning is not required. If the number of driving cycles is not less than the specified number of driving cycles, the step of determining whether cleaning the mixing valve is required is executed.

4. The method for pre- and post-processing of the low-pressure EGR system mixing valve feedback control phase according to claim 3, characterized in that: In the post-processing stage, if the number of driving cycles is not less than the specified number of driving cycles, if the mixing valve needs to be cleaned, the position learning action of the mixing valve is performed after the cleaning action is completed. If the mixing valve does not need to be cleaned, the position learning action of the mixing valve is performed directly; if the cleaning action fails, a fault code is reported and the EGR system is prohibited from working the next time it needs to work.

5. The method for pre- and post-processing of the low-pressure EGR system mixing valve feedback control phase according to claim 1, characterized in that: In the pre-processing stage and the post-processing stage, the maximum position sensing and the minimum position sensing are used to determine whether the mixing valve needs to be cleaned.

6. The method for pre- and post-processing of the low-pressure EGR system mixing valve feedback control phase according to claim 5, characterized in that: The method for maximum position awareness includes: When entering the maximum position awareness phase, the total time of the maximum position awareness phase begins to accumulate; Provide the mixing valve motor with a calibrated maximum position opening that needs to be sensed, so that the valve body of the mixing valve moves toward the maximum position; If the absolute position is greater than 99%, or the actual relative opening of the mixing valve is greater than 95%, the stabilization time for sensing the maximum position begins to accumulate; When the stabilization time for sensing the maximum position is greater than the standard stabilization time, the maximum position sensing is considered to be completed and the minimum position sensing phase is entered; otherwise, the maximum position sensing phase continues; When the total time of the maximum position sensing stage is greater than the total time of the standard sensing stage, it is considered that the maximum sensing has timed out and the sensing has failed, and it is determined that the mixing valve needs to be cleaned.

7. The method for pre- and post-processing of the low-pressure EGR system mixing valve feedback control phase according to claim 5, characterized in that: The method of minimum location awareness includes: When entering the minimum position awareness phase, the total time of the minimum position awareness phase begins to accumulate; Provide the mixing valve motor with a calibratable default minimum position opening, so that the valve body of the mixing valve moves toward the minimum position; If the absolute position is less than 3% or the actual relative opening of the mixing valve is less than 1%, the stabilization time for sensing the minimum position starts to accumulate; When the stabilization time for sensing the minimum position is greater than the standard stabilization time, the minimum position sensing is considered to be completed and the sensing is considered successful; otherwise, the minimum position sensing is continued; When the total time of the minimum position sensing stage is greater than the total time of the standard sensing stage, it is considered that the minimum sensing has timed out and the sensing has failed, and it is determined that the mixing valve needs to be cleaned.

8. The method for pre- and post-processing of a low-pressure EGR system mixing valve feedback control phase according to claim 1, characterized in that: In the pre-processing stage and the post-processing stage, the maximum position cleaning control method in the cleaning action control method includes: After entering the maximum position cleaning phase, the total time of the maximum position cleaning phase begins to accumulate; Give the mixing valve motor an opening for maximum position cleaning, so that the valve body of the mixing valve moves toward the maximum position to perform valve flushing cleaning; If the absolute position is greater than 99%, or the actual relative opening of the mixing valve is greater than 95%, the stabilization time for cleaning the maximum position begins to accumulate; When the stabilization time for cleaning the maximum position is greater than the standard stabilization time, the maximum position cleaning is considered completed and the minimum position cleaning phase is entered, and the maximum position cleaning failure flag is set to false. Otherwise, the maximum position cleaning continues. When the total time of the maximum cleaning phase is greater than the total time of the standard cleaning phase, it is considered that the maximum position cleaning has failed, and the maximum position cleaning failure flag is set to true.

9. The method for pre- and post-processing of a low-pressure EGR system mixing valve feedback control phase according to claim 1, characterized in that: In the pre-processing stage and the post-processing stage, the minimum position cleaning control method in the cleaning action control method includes: After entering the minimum position cleaning phase, the total time of the minimum position cleaning phase begins to accumulate; Give the mixing valve motor an opening for minimum position cleaning, so that the valve body of the mixing valve moves toward the minimum position to perform valve flushing cleaning; If the absolute position is less than 3%, or the actual relative opening of the mixing valve is less than 1%, the stabilization time for cleaning the minimum position starts to accumulate; When the stabilization time for cleaning the minimum position is greater than the standard stabilization time, the minimum position cleaning is considered completed, and the minimum position cleaning failure flag is set to false. Otherwise, the minimum position cleaning continues. When the total time of the minimum cleaning phase is greater than the total time of the standard cleaning phase, it is considered that the minimum position cleaning has failed, and the minimum position cleaning failure flag is set to true.

10. A computer-readable storage medium having executable instructions stored thereon, characterized in that: When the instruction is executed by the processor, the processor implements the steps of the pre- and post-processing method of the low-pressure EGR system mixing valve feedback control stage as described in any one of claims 1 to 9.

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