Method and device for diagnosing engine idle instability

Abstract

The application discloses a diagnosis method and device for engine idle speed instability, which comprises the following steps: determining whether the running state of a natural gas engine meets a preset condition according to the working condition parameters of the natural gas engine; in the case where the running state meets the preset condition, determining a first speed fluctuation index based on the engine speed of the natural gas engine within a first preset time; if the first speed fluctuation index does not meet a preset range, executing a target event; after the target event occurs and lasts for a second preset time, determining a second speed fluctuation index based on the engine speed of the natural gas engine within a third preset time; and if the second speed fluctuation index meets the preset range, generating a fault alarm. The method is based on the working condition parameters, and the first speed fluctuation index and the second speed fluctuation index are used as reference basis, so that whether the engine idle speed instability is caused by large EGR valve zero point leakage can be accurately diagnosed, and the efficiency and real-time performance of the diagnosis are effectively improved.

Description

Technical Field

[0001] This application relates to the field of natural gas engines, and more particularly to a diagnostic method and apparatus for unstable engine idling. Background Technology

[0002] The current China VI emission standard natural gas engines adopt the stoichiometric combustion technology route. In order to reduce engine combustion temperature, knocking tendency and optimize emissions, the EGR (Exhaust Gas Recirculation) system is a standard feature of China VI natural gas engines. Since natural gas engines are more sensitive to the intake system, if exhaust gas mixes into the intake air at low loads such as idling, it often leads to unstable idling or even stalling. Therefore, the control precision of the EGR valve for natural gas engines is higher than that for diesel engines. In particular, the zero-point leakage of the EGR valve (referring to the actual flow of exhaust gas through the EGR valve when the EGR valve is 0 degrees open (fully closed)) needs to be strictly controlled.

[0003] Under normal circumstances, the EGR valve only opens under medium to high loads, thus avoiding the aforementioned problems. However, in actual use, issues such as EGR valve aging, wear, carbon buildup, position sensor drift, and poor manufacturing consistency can arise. This often results in large zero-point leakage of the EGR valve, causing exhaust gas to enter the cylinder and participate in combustion. It also causes inaccurate intake system flow calculations, ultimately leading to unstable engine speed. Because many factors affect idle speed control, it is difficult to directly pinpoint large zero-point leakage of the EGR valve when unstable speed occurs. It requires item-by-item troubleshooting or on-vehicle testing to confirm, which is not timely and is time-consuming. Summary of the Invention

[0004] This application provides a diagnostic method and device for unstable engine idling, with the aim of accurately diagnosing whether unstable idling in a natural gas engine is caused by large zero-point leakage of the EGR valve.

[0005] To achieve the above objectives, this application provides the following technical solution:

[0006] A diagnostic method for unstable engine idling includes:

[0007] Based on the real-time acquired operating parameters of the natural gas engine, determine whether the operating status of the natural gas engine meets the preset conditions.

[0008] When the operating state of the natural gas engine meets the preset conditions, a first speed fluctuation index is determined based on the engine speed of the natural gas engine within a first preset time period.

[0009] If the first speed fluctuation index does not meet the preset range, execute the target event; the target event is: set the EGR valve drive duty cycle to the first calibration value;

[0010] After the target event occurs and lasts for a second preset time, a second speed fluctuation index is determined based on the engine speed of the natural gas engine within a third preset time.

[0011] If the second speed fluctuation index meets the preset range, a fault alarm for large zero-point leakage of the EGR valve and a first prompt message are generated; the first prompt message is used to indicate that the reason for unstable idling speed is large zero-point leakage of the EGR valve.

[0012] Optionally, based on the real-time acquired operating parameters of the natural gas engine, it is determined whether the operating status of the natural gas engine meets preset conditions, including:

[0013] Real-time acquisition of operating parameters of the natural gas engine; the operating parameters include at least the idle speed status, neutral signal status, EGR system status, EGR valve required opening degree, EGR valve actual opening degree, and EGR valve drive duty cycle;

[0014] When the idling state is idling condition, the neutral signal state is vehicle stationary, the EGR system state is fault-free, the EGR valve required opening degree is 0, the EGR valve actual opening degree is 0, and the EGR valve drive duty cycle is less than or equal to 0, the operating state of the natural gas engine is determined to meet the preset conditions.

[0015] Optionally, if the operating state of the natural gas engine meets the preset conditions, a first speed fluctuation index is determined based on the engine speed of the natural gas engine within a first preset time period, including:

[0016] When the operating status of the natural gas engine meets the preset conditions, the number of times the engine speed deviates from the idle speed set value within a first preset time period is monitored in real time, as well as the speed deviation amount corresponding to each deviation.

[0017] The first total deviation is determined by summing the absolute values ​​of the speed deviations corresponding to each deviation behavior within the first preset time period.

[0018] The first speed fluctuation index is determined based on the ratio between the first total deviation and the number of times the engine speed deviates from the idle speed setting value within the first preset time period.

[0019] Optionally, after the target event occurs and lasts for a second preset time, a second speed fluctuation index is determined based on the engine speed of the natural gas engine within a third preset time, including:

[0020] After the target event occurs and lasts for a second preset time, the number of times the engine speed of the natural gas engine deviates from the idle speed set value within a third preset time is monitored in real time, as well as the speed deviation amount corresponding to each deviation behavior.

[0021] The second total deviation is determined by summing the absolute values ​​of the speed deviations corresponding to each deviation behavior within the third preset time period.

[0022] The second speed fluctuation index is determined based on the ratio between the second total deviation and the number of times the engine speed deviates from the idle speed setting value within the third preset time period.

[0023] Optionally, after generating a fault alarm for high zero-point leakage of the EGR valve and corresponding prompt information, the method further includes:

[0024] The preset input-output control relationship is adjusted so that the target output value corresponding to the target input value in the adjusted input-output control relationship is changed to the second calibration value; the input-output control relationship is used to respond to the EGR valve demand duty cycle input by the EGR system and output the corresponding EGR valve drive duty cycle to the EGR valve; the target input value represents the input value when the EGR valve demand duty cycle is 0, and the target output value represents the EGR valve drive duty cycle corresponding to the input value when the EGR valve demand duty cycle is 0.

[0025] Optionally, the method further includes:

[0026] If the first speed fluctuation index meets the preset range, an engine idling instability fault alarm and a second prompt message are generated; the second prompt message is for EGR valve zero-point leakage to meet the standard.

[0027] Optionally, the method further includes:

[0028] If the second speed fluctuation index does not meet the preset range, an engine idling instability fault alarm and a second prompt message are generated; the second prompt message is for EGR valve zero-point leakage to meet the standard.

[0029] A diagnostic device for unstable engine idling, comprising:

[0030] The idling state determination unit is used to determine whether the operating state of the natural gas engine meets preset conditions based on the operating parameters of the natural gas engine acquired in real time.

[0031] The first index determination unit is used to determine a first speed fluctuation index based on the engine speed of the natural gas engine within a first preset time, when the operating state of the natural gas engine meets the preset conditions.

[0032] The target event execution unit is used to execute a target event if the first speed fluctuation index does not meet the preset range; the target event is: setting the EGR valve drive duty cycle to a first calibration value.

[0033] The second indicator determination unit is used to determine a second speed fluctuation indicator based on the engine speed of the natural gas engine within a third preset time after the target event occurs and lasts for a second preset time.

[0034] An alarm notification unit is used to generate a fault alarm and a first notification message if the second speed fluctuation index meets the preset range; the first notification message is used to indicate that the reason for unstable idling speed is large zero-point leakage of the EGR valve.

[0035] A storage medium comprising a stored program, wherein the program is executed by a processor to perform the diagnostic method for unstable engine idling.

[0036] A vehicle includes: a processor, a memory, and a bus; the processor and the memory are connected via the bus.

[0037] The memory is used to store a program, and the processor is used to run the program, wherein the program is executed by the processor to perform the diagnostic method for unstable engine idling.

[0038] The technical solution provided in this application determines whether the operating status of a natural gas engine meets preset conditions based on real-time acquired operating parameters. If the operating status meets the preset conditions, a first speed fluctuation index is determined based on the engine speed within a first preset time period. If the first speed fluctuation index does not meet the preset range, a target event is executed. The target event is: after the target event occurs and lasts for a second preset time, a second speed fluctuation index is determined based on the engine speed within a third preset time period. If the second speed fluctuation index meets the preset range, a fault alarm for large zero-point leakage of the EGR valve and a first prompt message are generated. This application, based on the operating parameters of the natural gas engine and using the first and second speed fluctuation indices as references, accurately diagnoses whether unstable idling speed of the natural gas engine is caused by large zero-point leakage of the EGR valve, effectively improving the efficiency and real-time performance of the diagnosis. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 A flowchart illustrating a diagnostic method for unstable engine idling speed provided in an embodiment of this application;

[0041] Figure 2 A flowchart illustrating another diagnostic method for unstable engine idling speed provided in this application embodiment;

[0042] Figure 3 A flowchart illustrating another diagnostic method for unstable engine idling speed provided in this application embodiment;

[0043] Figure 4 A flowchart illustrating another diagnostic method for unstable engine idling speed provided in this application embodiment;

[0044] Figure 5 A flowchart illustrating another diagnostic method for unstable engine idling speed provided in this application embodiment;

[0045] Figure 6 This is a schematic diagram of the architecture of a diagnostic device for unstable engine idling speed provided in an embodiment of this application. Detailed Implementation

[0046] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0047] In this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. The terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0048] like Figure 1 The diagram shown is a flowchart of a diagnostic method for unstable engine idling provided in an embodiment of this application. It can be applied to an ECU (Electronic Control Unit) and includes the following steps.

[0049] S101: Based on the real-time acquired operating parameters of the natural gas engine, determine whether the operating status of the natural gas engine meets the preset conditions.

[0050] The preset conditions can be set based on the failure point of the EGR valve and the speed difference between the engine speed when the EGR valve is working and when the EGR valve is in failure under specific operating conditions of the same engine. This will improve the accuracy of fault diagnosis (specifically, unstable idling speed) without affecting the normal operation of the natural gas engine and the EGR valve.

[0051] In some examples, failure points of EGR valves include, but are not limited to: EGR valve aging, wear, carbon buildup, position sensor drift, and poor manufacturing consistency of EGR valves.

[0052] It should be noted that, based on the failure point of the EGR valve and the speed differences under specific engine operating conditions, it is possible to identify under what operating conditions a large zero-point leakage of the EGR valve might cause unstable idling in a natural gas engine. Specifically, the operating state of a natural gas engine is related to its operating parameters, which further confirms under what operating parameters a large zero-point leakage of the EGR valve might cause unstable idling in a natural gas engine.

[0053] Optionally, the process of determining whether the operating status of the natural gas engine meets the preset conditions based on the real-time acquired operating parameters of the natural gas engine can be found in [reference needed]. Figure 2 The steps shown are accompanied by corresponding explanations.

[0054] In some examples, if the operating conditions of the natural gas engine meet the preset conditions, it can be determined that the unstable idling speed of the natural gas engine may be caused by a large zero-point leakage of the EGR valve. If the operating conditions of the natural gas engine do not meet the preset conditions, it can be determined that the unstable idling speed of the natural gas engine is not caused by a large zero-point leakage of the EGR valve.

[0055] Understandably, by using the real-time operating parameters of the natural gas engine to determine whether the operating status of the natural gas engine meets the preset conditions, it is possible to identify whether the natural gas engine is in an unstable idling state, and to preliminarily identify whether the cause of the unstable idling is related to the large zero-point leakage of the EGR valve.

[0056] S102: When the operating conditions meet the preset conditions, determine the first speed fluctuation index based on the engine speed of the natural gas engine within the first preset time period.

[0057] The first preset time occurs after the operating status is detected to meet the preset conditions, and the specific duration of the first preset time can be set by technicians according to the actual situation.

[0058] Optionally, if the operating conditions meet preset conditions, the process of determining the first speed fluctuation index based on the engine speed of the natural gas engine within a first preset time period can be found in [reference needed]. Figure 3 The steps shown are accompanied by corresponding explanations.

[0059] S103: If the first speed fluctuation index does not meet the preset range, execute the target event.

[0060] The target event is: setting the EGR valve drive duty cycle to a first calibration value, and this first calibration value is negative.

[0061] Optionally, if the first speed fluctuation index meets the preset range, a fault alarm for unstable engine idling and a second prompt message are generated. The second prompt message is used to indicate that the zero-point leakage of the EGR valve meets the standard.

[0062] It should be noted that if the first speed fluctuation index is within the preset range, it can be considered that the main cause of unstable engine idling is not the large zero-point leakage of the EGR valve. Therefore, an engine idling instability fault alarm and a second prompt message are generated to inform the owner to check whether other components besides the EGR valve and related components (such as the position sensor of the EGR valve) are faulty.

[0063] In a possible implementation, if the first speed fluctuation index does not meet the preset range, the ECU can adjust the EGR valve drive duty cycle to the first calibration value.

[0064] It is important to note that adjusting the EGR valve drive duty cycle to the first calibration value is intended to reverse the closing of the EGR valve, so as to further determine whether the main cause of unstable engine idling is large zero-point leakage of the EGR valve, prevent misdiagnosis, and thus improve diagnostic accuracy.

[0065] S104: After the target event occurs and lasts for a second preset time, determine the second speed fluctuation index based on the engine speed of the natural gas engine within a third preset time.

[0066] The third preset time occurs after the target event has occurred and lasted for the second preset time, and the specific duration of the third preset time can be set by technical personnel according to the actual situation.

[0067] Optionally, after the target event occurs and lasts for a second preset time, the process of determining the second speed fluctuation index based on the engine speed of the natural gas engine within a third preset time can be found in [reference needed]. Figure 4 The steps shown are accompanied by corresponding explanations.

[0068] S105: If the second speed fluctuation index meets the preset range, generate a fault alarm for large zero-point air leakage of the EGR valve and the first prompt message.

[0069] The first warning message indicates that the unstable idling speed is caused by a large amount of air leakage at the zero point of the EGR valve.

[0070] Optionally, if the second speed fluctuation index does not meet the preset range, a fault alarm for unstable engine idling and a second prompt message are generated. The second prompt message is used to ensure that the zero-point leakage of the EGR valve meets the standard.

[0071] In some examples, if the second speed fluctuation index is within the preset range, it can be determined that the main cause of the unstable idling speed of the natural gas engine is the large zero-point leakage of the EGR valve. If the second speed fluctuation index is not within the preset range, it can be determined that the main cause of the unstable idling speed of the natural gas engine is not the large zero-point leakage of the EGR valve.

[0072] Understandably, by using the first and second speed fluctuation indicators, it is possible to effectively identify whether the main cause of unstable idling is large zero-point leakage of the EGR valve, thereby achieving effective diagnosis of unstable idling.

[0073] It should be noted that when the operating status of the natural gas engine meets the preset conditions, the EGR valve is actively adjusted by executing the target event to further close the EGR valve in the reverse direction. By calculating (i.e., calculating the first and second speed fluctuation indices) and judging (i.e., comparing the first and second speed fluctuation indices with their respective preset ranges), it is confirmed whether the main cause of unstable engine idling is large zero-point leakage of the EGR valve. At the same time, the engine speed judgment and confirmation time before and after active diagnosis (i.e., the second preset time) is set to prevent misjudgment and further improve the accuracy of diagnosis.

[0074] Optionally, after determining that the main cause of unstable engine idling is large zero-point leakage of the EGR valve, the preset input-output control relationship can be adjusted so that the target output value corresponding to the target input value in the adjusted input-output control relationship is changed to the second calibration value. The input-output control relationship is used to respond to the EGR valve's required duty cycle input by the EGR system, outputting the corresponding EGR valve drive duty cycle to the EGR valve. The target input value represents the input value when the EGR valve's required duty cycle is 0, and the target output value represents the EGR valve drive duty cycle corresponding to the input value when the EGR valve's required duty cycle is 0.

[0075] In some examples, the input-output control relationship can be represented as a linearized curve in the ECU. The linearized curve can be understood as a one-dimensional array. The input value X (i.e., the duty cycle required by the EGR valve) yields the corresponding output Y (i.e., the duty cycle driven by the EGR valve) in the one-dimensional array.

[0076] It should be noted that the second calibration value can be set to a negative value. When it is confirmed that the main reason for unstable engine idling is the large leakage of the EGR valve at zero point, the EGR valve drive duty cycle when the required duty cycle of the EGR valve is 0 can be actively adjusted to ensure that the EGR valve is closed more tightly at zero point and reduce the leakage of the EGR valve.

[0077] Combination Figures 2-4 The method shown in the embodiments of this application, the diagnostic method for unstable engine idling speed, can also be summarized as follows: Figure 5 The process shown includes steps 1-9 as follows.

[0078] Step 1: Obtain operating parameters such as engine speed, idle speed setpoint, neutral signal status, idle speed status, EGR valve opening (including EGR valve required opening and EGR valve actual opening), and EGR valve drive duty cycle.

[0079] Step 2: Determine whether the current state of the engine (i.e. the operating state of the natural gas engine) meets the preset conditions. If the current state of the engine meets the preset conditions, proceed to step 3; otherwise, return to step 1.

[0080] Step 3: Calculate the average value N1 (i.e., the first speed fluctuation index) of the engine speed deviation from the idle speed setting value within the preset time T1 (i.e. the first preset time).

[0081] Step 4: Determine whether the average value N1 is within the preset range. If the average value N1 is within the preset range, the diagnosis ends; otherwise, proceed to Step 5.

[0082] Step 5: Set the EGR valve drive duty cycle to A (i.e., the first calibration value).

[0083] Step 6: After the stabilization time T2 (i.e., the second preset time), calculate the average value N2 (i.e., the second speed fluctuation index) of the engine speed deviation from the idle speed setting value within the preset time T3 (i.e., the third preset time).

[0084] Step 7: Determine whether the average value N2 is within the preset range. If the average value N2 is within the preset range, proceed to step 8; otherwise, end the diagnosis.

[0085] Step 8: Report a fault of excessive EGR valve leakage, and indicate that the main cause of unstable idling is excessive EGR valve leakage. It is recommended to inspect the EGR valve and related position sensors.

[0086] Step 9: Modify the EGR valve linearization CURVE so that the EGR valve demand duty cycle is 0, and set the corresponding EGR drive duty cycle to B (i.e., the second calibration value).

[0087] Based on the process shown in steps 1-9, by setting preset conditions under specific operating conditions, the automatic diagnosis of engine speed instability caused by large zero-point leakage of the EGR valve is realized. This improves the accuracy of problem diagnosis and shortens the diagnosis time. At the same time, by actively modifying the EGR valve drive duty cycle corresponding to the EGR valve demand duty cycle at the zero-point position of the EGR valve after identifying the above problems, the problem of zero-point leakage of the EGR valve is improved. To a certain extent, this solves the problem of engine speed instability caused by EGR valve aging, wear, carbon deposits, position sensor drift, and poor EGR valve production consistency, thereby improving the reliability of the EGR system.

[0088] The procedures shown in S101-S105 above, based on the operating parameters of the natural gas engine and combined with the first and second speed fluctuation indicators as references, accurately diagnose whether the unstable idling speed of the natural gas engine is caused by a large amount of zero-point leakage of the EGR valve, effectively improving the efficiency and real-time performance of the diagnosis.

[0089] like Figure 2 The diagram shown is a flowchart illustrating another diagnostic method for unstable engine idling provided in this application, including the following steps.

[0090] S201: Real-time acquisition of operating parameters of natural gas engine.

[0091] The operating parameters include at least the idle speed status, neutral signal status, EGR system status, EGR valve required opening degree, EGR valve actual opening degree, and EGR valve drive duty cycle.

[0092] Among them, the idle speed status, neutral signal status, EGR system status, EGR valve required opening degree, EGR valve actual opening degree, and EGR valve drive duty cycle can be directly read from the vehicle's ECU.

[0093] In some examples, the idling state is determined based on the engine idling state setting in the ECU. If the engine idling state setting is 1, it means that the idling state is idling; if the engine idling state setting is 0, it means that the idling state is not idling.

[0094] In some examples, the neutral signal status is determined based on the neutral signal setting in the ECU. If the neutral signal is set to 1, it means that the vehicle is stationary (i.e., the transmission system is disconnected). If the neutral signal is set to 0, it means that the vehicle is not stationary (i.e., the transmission system is not disconnected).

[0095] In some examples, if the EGR system is fault-free, the EGR system status is fault-free; if the EGR system has a fault, the EGR system status is the fault code corresponding to the fault.

[0096] In some examples, the EGR valve opening requirement is an opening command issued by the EGR system to the EGR valve, so that the EGR valve responds to the EGR valve opening requirement and performs opening control operations.

[0097] In some examples, the actual opening degree of the EGR valve is the actual opening degree after the EGR valve performs the opening control operation.

[0098] In some examples, the EGR valve drive duty cycle refers to the ratio of the time within one cycle that is at a high level, used to control the degree of opening of the EGR valve. The duty cycle is defined as the ratio of the duration of the positive pulse to the total period of the pulse, usually expressed as a percentage.

[0099] S202: When the idling state is idling condition, the neutral signal state is vehicle stationary, the EGR system state is fault-free, the EGR valve required opening degree is 0, the EGR valve actual opening degree is 0, and the EGR valve drive duty cycle is less than or equal to 0, the operating state of the natural gas engine is determined to meet the preset conditions.

[0100] Specifically, when the idling state is idle, the neutral signal state is the vehicle stationary, the EGR system state is fault-free, the EGR valve required opening degree is 0, the EGR valve actual opening degree is 0, and the EGR valve drive duty cycle is less than or equal to 0, it can be determined that the natural gas engine is in an unstable idling state.

[0101] In some examples, when the idling state is not idling, and / or the neutral signal state is that the vehicle is not stationary, and / or the EGR system state is faulty, and / or the EGR valve demand opening is not 0, and / or the EGR valve actual opening is not 0, and / or the EGR valve drive duty cycle is greater than 0, it can be determined that the operating state does not meet the preset conditions, that is, there is no need to diagnose whether the unstable idling speed of the natural gas engine is caused by the large zero-point leakage of the EGR valve.

[0102] The processes shown in S201-S202 above can use the real-time acquired operating parameters of the natural gas engine to determine whether the operating status of the natural gas engine meets the preset conditions, identify whether the natural gas engine is in an unstable idling state, and preliminarily identify whether the cause of the unstable idling is related to the large zero-point leakage of the EGR valve.

[0103] like Figure 3 The diagram shown is a flowchart illustrating another diagnostic method for unstable engine idling provided in this application, including the following steps.

[0104] S301: When the operating conditions meet the preset conditions, monitor in real time the number of times the engine speed of the natural gas engine deviates from the idle speed set value within the first preset time, and the speed deviation amount corresponding to each deviation.

[0105] Specifically, if the engine speed is greater than the idle speed setting, the corresponding speed deviation is positive; if the engine speed is less than the idle speed setting, the corresponding speed deviation is negative.

[0106] In some examples, the idle speed setting can be set by a technician based on the actual situation.

[0107] In a possible implementation, the engine speed of the natural gas engine can be monitored in real time within a first preset time period, and the monitored multiple engine speeds can be compared with the idle speed set value to obtain the number of times the engine speed deviates from the idle speed set value within the first preset time period, and the speed deviation amount corresponding to each deviation.

[0108] S302: The first total deviation is determined by summing the absolute values ​​of the speed deviations corresponding to each deviation behavior within a first preset time period.

[0109] In addition, after monitoring and obtaining the speed deviation corresponding to each deviation behavior, multiple speed deviations with positive values ​​can be accumulated to obtain a first offset with a positive value, and multiple speed deviations with negative values ​​can be accumulated to obtain a second offset with a negative value.

[0110] S303: The first speed fluctuation index is determined based on the ratio between the first total deviation and the number of times the engine speed deviates from the idle speed setting value within the first preset time period.

[0111] Specifically, the ratio between the first offset and the number of multiple speed deviations with positive values ​​can be determined as the first positive fluctuation index, and the ratio between the second offset and the number of multiple speed deviations with negative values ​​can be determined as the first negative fluctuation index. Based on the first positive fluctuation index and the first negative fluctuation index, the first speed fluctuation index can be determined.

[0112] In a possible implementation, if both the first positive fluctuation index and the first negative fluctuation index meet the preset range, then the first speed fluctuation index is determined to meet the preset range; if either the first positive fluctuation index or the first negative fluctuation index does not meet the preset range, then the first speed fluctuation index is determined to not meet the preset range.

[0113] The processes shown in S301-S303 above can determine the first speed fluctuation index based on the engine speed of the natural gas engine within a first preset time, providing a useful reference for the diagnosis of unstable engine idling.

[0114] like Figure 4 The diagram shown is a flowchart illustrating another diagnostic method for unstable engine idling provided in this application, including the following steps.

[0115] S401: After the target event occurs and lasts for a second preset time, monitor in real time the number of times the engine speed of the natural gas engine deviates from the idle speed set value within a third preset time, and the speed deviation amount corresponding to each deviation.

[0116] Among them, the engine speed of the natural gas engine can be monitored in real time within a third preset time period, and the monitored engine speeds are compared with the idle speed set value to obtain the number of times the engine speed deviates from the idle speed set value within the third preset time period, as well as the speed deviation amount corresponding to each deviation.

[0117] S402: The second total deviation is determined by summing the absolute values ​​of the speed deviations corresponding to each deviation behavior within the third preset time period.

[0118] In addition, after monitoring and obtaining the speed deviation amount corresponding to each deviation behavior, multiple speed deviation amounts with positive values ​​can be accumulated to obtain a third offset amount with positive values, and multiple speed deviation amounts with negative values ​​can be accumulated to obtain a fourth offset amount with negative values.

[0119] S403: The second speed fluctuation index is determined based on the ratio between the second total deviation and the number of times the engine speed deviates from the idle speed set value within the third preset time period.

[0120] Furthermore, the ratio between the third offset and the number of multiple speed deviations with positive values ​​can be determined as the second positive fluctuation index, and the ratio between the fourth offset and the number of multiple speed deviations with negative values ​​can be determined as the second negative fluctuation index. Based on the second positive fluctuation index and the second negative fluctuation index, the second speed fluctuation index can be determined.

[0121] In a possible implementation, if both the second positive fluctuation index and the second negative fluctuation index meet the preset range, then the second speed fluctuation index is determined to meet the preset range; if either the second positive fluctuation index or the second negative fluctuation index does not meet the preset range, then the second speed fluctuation index is determined to not meet the preset range.

[0122] The processes shown in S401-S403 above can determine the second speed fluctuation index based on the engine speed of the natural gas engine within a third preset time period, providing a useful reference for the diagnosis of unstable engine idling.

[0123] like Figure 6 The diagram shown is a schematic of the architecture of a diagnostic device for unstable engine idling speed provided in an embodiment of this application, including the following units.

[0124] The idling state determination unit 100 is used to determine whether the operating state of the natural gas engine meets preset conditions based on the real-time acquired operating parameters of the natural gas engine.

[0125] Optionally, the idle speed state determination unit 100 is specifically used to: acquire the operating parameters of the natural gas engine in real time; the operating parameters include at least the idle speed state, neutral signal state, EGR system state, EGR valve required opening degree, EGR valve actual opening degree, and EGR valve drive duty cycle; when the idle speed state is idle operating condition, the neutral signal state is vehicle stationary, the EGR system state is fault-free, the EGR valve required opening degree is 0, the EGR valve actual opening degree is 0, and the EGR valve drive duty cycle is less than or equal to 0, the operating state of the natural gas engine is determined to meet the preset conditions.

[0126] The first indicator determination unit 200 is used to determine the first speed fluctuation indicator based on the engine speed of the natural gas engine within a first preset time period, provided that the operating state meets the preset conditions.

[0127] Optionally, the first indicator determination unit 200 is specifically used to: when the operating state meets preset conditions, monitor in real time the number of times the engine speed of the natural gas engine deviates from the idle speed set value within a first preset time period, and the speed deviation amount corresponding to each deviation behavior; determine the first total deviation amount based on the cumulative sum of the absolute values ​​of the speed deviation amounts corresponding to each deviation behavior within the first preset time period; and determine the first speed fluctuation index based on the ratio between the first total deviation amount and the number of times the engine speed deviates from the idle speed set value within the first preset time period.

[0128] The target event execution unit 300 is used to execute a target event if the first speed fluctuation index does not meet the preset range; the target event is: set the EGR valve drive duty cycle to the first calibration value.

[0129] The second indicator determination unit 400 is used to determine a second speed fluctuation indicator based on the engine speed of the natural gas engine within a third preset time after the target event occurs and lasts for a second preset time.

[0130] Optionally, the second indicator determination unit 400 is specifically used to: after the target event occurs and lasts for a second preset time, monitor in real time the number of times the engine speed of the natural gas engine deviates from the idle speed set value within a third preset time, and the speed deviation amount corresponding to each deviation behavior; determine the second total deviation amount based on the cumulative sum of the absolute values ​​of the speed deviation amounts corresponding to each deviation behavior within the third preset time; and determine the second speed fluctuation index based on the ratio between the second total deviation amount and the number of times the engine speed deviates from the idle speed set value within the third preset time.

[0131] The alarm prompting unit 500 is used to generate a fault alarm and a first prompting message if the second speed fluctuation index meets the preset range; the first prompting message is used to indicate that the reason for the unstable idle speed is the large zero-point leakage of the EGR valve.

[0132] Optionally, the alarm notification unit 500 is also used to: generate an engine idling instability fault alarm and a second notification message if the first speed fluctuation index meets the preset range; the second notification message is used to indicate that the EGR valve zero-point leakage meets the standard.

[0133] Optionally, the alarm notification unit 500 is also used to: generate an engine idling instability fault alarm and a second notification message if the second speed fluctuation index does not meet the preset range; the second notification message is used to ensure that the EGR valve zero-point leakage meets the standard.

[0134] The fault repair unit 600 is used to adjust the preset input-output control relationship so that the target output value corresponding to the target input value in the adjusted input-output control relationship is changed to the second calibration value; the input-output control relationship is used to respond to the EGR valve demand duty cycle input by the EGR system and output the corresponding EGR valve drive duty cycle to the EGR valve; the target input value represents the input value when the EGR valve demand duty cycle is 0, and the target output value represents the EGR valve drive duty cycle corresponding to the input value when the EGR valve demand duty cycle is 0.

[0135] The units shown above, based on the operating parameters of the natural gas engine and combined with the first and second speed fluctuation indicators as references, accurately diagnose whether the unstable idling speed of the natural gas engine is caused by a large amount of zero-point leakage of the EGR valve, effectively improving the efficiency and real-time performance of the diagnosis.

[0136] This application also provides a computer-readable storage medium including a stored program, wherein the program executes the engine idling instability diagnostic method provided in this application.

[0137] This application also provides a vehicle, including a processor, a memory, and a bus. The processor and the memory are connected via the bus. The memory is used to store a program, and the processor is used to run the program. When the program runs, it executes the diagnostic method for unstable engine idling provided in this application.

[0138] Furthermore, the functions described above in the embodiments of this application can be performed at least in part by one or more hardware logic components. For example, without limitation, exemplary types of hardware logic components that can be used include: Field Programmable Gate Arrays (FPGAs), Application-Specific Integrated Circuits (ASICs), Application Standard Products (ASSPs), System-on-Chip (SOCs), Complex Programmable Logic Devices (CPLDs), and so on.

[0139] While several specific implementation details are included in the foregoing discussion, these should not be construed as limiting the scope of this application. Certain features described in the context of individual embodiments may also be implemented in combination in a single embodiment. Conversely, various features described in the context of a single embodiment may also be implemented individually or in any suitable sub-combination in multiple embodiments.

[0140] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of disclosure in this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the above-described concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this application.

Claims

1. A diagnostic method for unstable engine idling speed, characterized in that, include: Based on the real-time acquired operating parameters of the natural gas engine, determine whether the operating status of the natural gas engine meets preset conditions, including: acquiring the operating parameters of the natural gas engine in real time; the operating parameters include at least idling status, neutral signal status, EGR system status, EGR valve required opening degree, EGR valve actual opening degree, and EGR valve drive duty cycle; when the idling status is idling condition, the neutral signal status is vehicle stationary, the EGR system status is fault-free, the EGR valve required opening degree is 0, the EGR valve actual opening degree is 0, and the EGR valve drive duty cycle is less than or equal to 0, determine that the operating status of the natural gas engine meets the preset conditions; When the operating state of the natural gas engine meets the preset conditions, a first speed fluctuation index is determined based on the engine speed of the natural gas engine within a first preset time period. If the first speed fluctuation index indicates that the main cause of unstable engine idling may be large zero-point leakage of the EGR valve, then execute the target event; the target event is: set the EGR valve drive duty cycle to a first calibration value; the first calibration value is negative; setting the EGR valve drive duty cycle to the first calibration value is mainly used to reverse the closing of the EGR valve; After the target event occurs and lasts for a second preset time, a second speed fluctuation index is determined based on the engine speed of the natural gas engine within a third preset time. If the second speed fluctuation index indicates that the main cause of unstable engine idling is large zero-point leakage of the EGR valve, a fault alarm for large zero-point leakage of the EGR valve and a first prompt message are generated; the first prompt message is used to indicate that the cause of unstable idling is large zero-point leakage of the EGR valve.

2. The method according to claim 1, characterized in that, When the operating state of the natural gas engine meets the preset conditions, a first speed fluctuation index is determined based on the engine speed of the natural gas engine within a first preset time period, including: When the operating status of the natural gas engine meets the preset conditions, the number of times the engine speed deviates from the idle speed set value within a first preset time period is monitored in real time, as well as the speed deviation amount corresponding to each deviation. The first total deviation is determined by summing the absolute values ​​of the speed deviations corresponding to each deviation behavior within the first preset time period. The first speed fluctuation index is determined based on the ratio between the first total deviation and the number of times the engine speed deviates from the idle speed setting value within the first preset time period.

3. The method according to claim 1, characterized in that, After the target event occurs and lasts for a second preset time, a second speed fluctuation index is determined based on the engine speed of the natural gas engine within a third preset time, including: After the target event occurs and lasts for a second preset time, the number of times the engine speed of the natural gas engine deviates from the idle speed set value within a third preset time is monitored in real time, as well as the speed deviation amount corresponding to each deviation behavior. The second total deviation is determined by summing the absolute values ​​of the speed deviations corresponding to each deviation behavior within the third preset time period. The second speed fluctuation index is determined based on the ratio between the second total deviation and the number of times the engine speed deviates from the idle speed setting value within the third preset time period.

4. The method according to claim 1, characterized in that, After generating the fault alarm for large zero-point leakage of the EGR valve and the first prompt message, the method further includes: The preset input-output control relationship is adjusted so that the target output value corresponding to the target input value in the adjusted input-output control relationship is changed to the second calibration value; the input-output control relationship is used to respond to the EGR valve demand duty cycle input by the EGR system and output the corresponding EGR valve drive duty cycle to the EGR valve; the target input value represents the input value when the EGR valve demand duty cycle is 0, and the target output value represents the EGR valve drive duty cycle corresponding to the input value when the EGR valve demand duty cycle is 0.

5. The method according to claim 1, characterized in that, The method further includes: If the first speed fluctuation indicator indicates that the main cause of unstable engine idling is not a large zero-point leakage of the EGR valve, an engine idling instability fault alarm and a second prompt message are generated; the second prompt message is used to indicate that the zero-point leakage of the EGR valve meets the standard.

6. The method according to claim 1, characterized in that, The method further includes: If the second speed fluctuation indicator indicates that the main cause of unstable engine idling is not a large zero-point leakage of the EGR valve, an engine idling instability fault alarm and a second prompt message are generated; the second prompt message is used to indicate that the zero-point leakage of the EGR valve meets the standard.

7. A diagnostic device for unstable engine idling speed, characterized in that, include: The idling state determination unit is used to determine whether the operating state of the natural gas engine meets preset conditions based on the operating parameters of the natural gas engine acquired in real time. The idle speed state determination unit is specifically used to: acquire the operating parameters of the natural gas engine in real time; the operating parameters include at least the idle speed state, neutral signal state, EGR system state, EGR valve required opening degree, EGR valve actual opening degree, and EGR valve drive duty cycle. When the idling state is idling condition, the neutral signal state is vehicle stationary, the EGR system state is fault-free, the EGR valve required opening degree is 0, the EGR valve actual opening degree is 0, and the EGR valve drive duty cycle is less than or equal to 0, the operating state of the natural gas engine is determined to meet the preset conditions. The first index determination unit is used to determine a first speed fluctuation index based on the engine speed of the natural gas engine within a first preset time, when the operating state of the natural gas engine meets the preset conditions. The target event execution unit is configured to execute a target event if the first speed fluctuation index indicates that the main cause of unstable engine idling may be large zero-point leakage of the EGR valve; the target event is: setting the EGR valve drive duty cycle to a first calibration value. The first calibration value is negative; Setting the EGR valve drive duty cycle to the first calibration value is mainly used to reverse the closing of the EGR valve; The second indicator determination unit is used to determine a second speed fluctuation indicator based on the engine speed of the natural gas engine within a third preset time after the target event occurs and lasts for a second preset time. The alarm unit is used to generate a fault alarm for large zero-point leakage of the EGR valve and a first prompt message if the second speed fluctuation index indicates that the main cause of unstable engine idling is large zero-point leakage of the EGR valve; the first prompt message is used to indicate that the cause of unstable idling is large zero-point leakage of the EGR valve.

8. A storage medium, characterized in that, The storage medium includes a stored program, wherein the program is executed by a processor to perform the diagnostic method for unstable engine idling as described in any one of claims 1-6.

9. A vehicle, characterized in that, include: Processor, memory, and bus; The processor and the memory are connected via the bus; The memory is used to store a program, and the processor is used to run the program, wherein the program is executed by the processor to perform the diagnostic method for unstable engine idling as described in any one of claims 1-6.

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