Method and device for diagnosing unstable idle speed of engine

Abstract

The invention discloses a diagnosis method and device for unstable idle speed of an engine, and the method comprises the steps: judging whether the operation state of the natural gas engine meets a preset condition or not according to the working condition parameters of the natural gas engine; under the condition that the running state meets the preset condition, a first rotating speed fluctuation index is determined based on the engine rotating speed of the natural gas engine within the first preset time; if the first rotating speed fluctuation index does not accord with the preset range, executing the target event; after the target event occurs and lasts for a second preset time, a second rotating speed fluctuation index is determined based on the engine rotating speed of the natural gas engine within a third preset time; and if the second rotating speed fluctuation index accords with a preset range, generating a fault alarm. According to the method, on the basis of the working condition parameters, the first rotating speed fluctuation index and the second rotating speed fluctuation index are combined to serve as reference bases, whether the unstable idle speed of the engine is caused by large EGR valve zero-point air leakage or not is accurately diagnosed, and the diagnosis efficiency and real-time performance are effectively improved.

Description

Technical Field

[0001] The present application relates to the field of natural gas engines, and in particular to a method and device for diagnosing unstable engine idling. Background Art

[0002] The current National VI natural gas engine adopts the equivalent combustion technology route. In order to reduce the engine combustion temperature, knock tendency and optimize emissions, the EGR (Exhaust Gas Recirculation) system is a standard feature of the National VI natural gas engine. Since the natural gas engine is sensitive to the intake system, if exhaust gas is mixed into the intake air at low loads such as idling, it will often lead to unstable idling or even flameout. Therefore, for natural gas engines, the control accuracy of the EGR valve is higher than that required by diesel engines, especially the EGR valve zero-point leakage (refers to the actual exhaust gas flow through the EGR valve when the opening of the EGR valve is 0 (fully closed). In theory, the smaller the leakage, the better, preferably 0. However, due to production consistency and problems such as EGR valve wear, aging, and carbon deposition, the zero-point leakage of the EGR valve will gradually increase, and a small amount of exhaust gas will enter the cylinder through the EGR circulation system to participate in combustion) needs to be strictly controlled.

[0003] Under normal circumstances, the EGR valve will only open under medium and high loads, thus avoiding the above problems. However, in actual use, there will be problems such as EGR valve aging, wear, carbon deposits, position sensor drift and poor consistency in EGR valve production. As a result, large zero-point leakage of the EGR valve is often seen in the market, causing exhaust gas to enter the cylinder to participate in combustion, while causing inaccurate flow calculation of the intake system and other problems, which ultimately leads to unstable engine speed. Because there are many factors affecting idle speed control, it is difficult to directly locate whether it is caused by large zero-point leakage of the EGR valve when the speed is unstable. It is necessary to check each item or follow-up test to confirm, which has poor real-time performance and wastes time. Summary of the invention

[0004] The present application provides a method and device for diagnosing unstable idle speed of an engine, the purpose of which is to accurately diagnose whether the unstable idle speed of a natural gas engine is caused by a large zero-point leakage of an EGR valve.

[0005] In order to achieve the above objectives, this application provides the following technical solutions:

[0006] A method for diagnosing unstable engine idle speed, comprising:

[0007] Determining whether the operating state of the natural gas engine meets a preset condition according to the operating parameters of the natural gas engine acquired in real time;

[0008] When the running state of the natural gas engine satisfies the preset condition, determining a first speed fluctuation index based on the engine speed of the natural gas engine within a first preset time;

[0009] If the first speed fluctuation index does not meet the preset range, executing a target event; the target event is: setting the EGR valve driving duty cycle to a first calibration value;

[0010] 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;

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

[0012] Optionally, judging whether the operating state of the natural gas engine meets a preset condition according to the operating parameters of the natural gas engine acquired in real time includes:

[0013] Acquire the operating parameters of the natural gas engine in real time; the operating parameters at least include idle state, neutral signal state, EGR system state, EGR valve required opening, EGR valve actual opening, and EGR valve drive duty cycle;

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

[0015] Optionally, when the running state of the natural gas engine 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 includes:

[0016] When the running state of the natural gas engine meets the preset condition, real-time monitoring is performed on the number of times the engine speed of the natural gas engine deviates from the idle speed setting value within the first preset time, and the speed deviation amount corresponding to each deviation behavior;

[0017] Determine a first total deviation based on the accumulated sum of the absolute values ​​of the rotation speed deviations corresponding to each deviation behavior within the first preset time;

[0018] A first speed fluctuation index is determined based on a 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.

[0019] Optionally, 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 includes:

[0020] After the target event occurs and lasts for a second preset time, real-time monitoring is performed on the number of times the engine speed of the natural gas engine deviates from the idle speed setting value within a third preset time, and the speed deviation amount corresponding to each deviation behavior;

[0021] Determine a second total deviation based on the accumulated sum of the absolute values ​​of the rotation speed deviations corresponding to each deviation behavior within the third preset time;

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

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

[0024] 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 a second calibrated 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, a fault alarm of unstable engine idle speed 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.

[0027] Optionally, the method further includes:

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

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

[0030] An idle state determination unit, used to determine whether the operating state of the natural gas engine meets a preset condition according to the operating parameters of the natural gas engine acquired in real time;

[0031] a first index determination unit, configured to determine a first speed fluctuation index based on an engine speed of the natural gas engine within a first preset time when the running state of the natural gas engine satisfies the preset condition;

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

[0033] A second index determination unit, configured to determine a second speed fluctuation index 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] The alarm prompt unit is used to generate a fault alarm of large EGR valve zero-point leakage and a first prompt message if the second speed fluctuation index meets the preset range; the first prompt message is used to prompt that the cause of the unstable idle speed is the large EGR valve zero-point leakage.

[0035] A storage medium includes a stored program, wherein the program is executed by a processor to execute the method for diagnosing unstable engine idle speed.

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

[0037] The memory is used to store programs, and the processor is used to run programs, wherein the program executes the method for diagnosing unstable engine idle speed when the processor runs the program.

[0038] The technical solution provided by the present application determines whether the operating state of the natural gas engine meets the preset conditions based on the operating parameters of the natural gas engine obtained in real time. When the operating state meets the preset conditions, a first speed fluctuation index is determined based on the engine speed of the natural gas engine within the first preset time. If the first speed fluctuation index does not meet the preset range, the 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 of the natural gas engine within a third preset time. If the second speed fluctuation index meets the preset range, a fault alarm of large zero-point leakage of the EGR valve and a first prompt message are generated. Based on the operating parameters of the natural gas engine, the present application combines the first speed fluctuation index and the second speed fluctuation index as a reference basis to accurately diagnose whether the unstable idling speed of the natural gas engine is caused by the large zero-point leakage of the EGR valve, thereby effectively improving the efficiency and real-time performance of the diagnosis. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0040] Figure 1 A flow chart of a method for diagnosing unstable engine idle speed provided in an embodiment of the present application;

[0041] Figure 2 A flow chart of another method for diagnosing unstable engine idle speed provided in an embodiment of the present application;

[0042] Figure 3 A flow chart of another method for diagnosing unstable engine idle speed provided in an embodiment of the present application;

[0043] Figure 4 A flow chart of another method for diagnosing unstable engine idle speed provided in an embodiment of the present application;

[0044] Figure 5 A flow chart of another method for diagnosing unstable engine idle speed provided in an embodiment of the present application;

[0045] Figure 6 A schematic diagram of the architecture of a diagnostic device for unstable engine idle speed provided in an embodiment of the present application. DETAILED DESCRIPTION

[0046] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0047] In this application, relational terms such as first and second, etc. are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. The terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of more restrictions, the elements defined by the sentence "comprise one..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0048] like Figure 1 As shown, it is a flow chart of a method for diagnosing unstable engine idle speed provided in an embodiment of the present application, which can be applied to an ECU (Electronic Control Unit) and includes the following steps.

[0049] S101: 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.

[0050] Among them, the preset conditions can be set according to the failure point of the EGR valve and the speed difference between the engine speed when the EGR valve is in a working state and the engine speed when the EGR valve is in a failed state under the same specific working conditions of the engine, so as to improve the accuracy of fault diagnosis (specifically unstable idle speed) without affecting the normal operation of the natural gas engine and the EGR valve.

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

[0052] It should be noted that, based on the failure point of the EGR valve and the speed difference under the same engine specific operating conditions, it can be confirmed under what operating conditions, the idle speed of the natural gas engine may be unstable due to the large zero-point leakage of the EGR valve. Specifically, the operating state of the natural gas engine is related to the operating parameters of the natural gas engine, so it can be further confirmed under what operating parameters, the idle speed of the natural gas engine may be unstable due to the large zero-point leakage of the EGR valve.

[0053] Optionally, the process of determining whether the operating state of the natural gas engine meets the preset conditions according to the operating parameters of the natural gas engine obtained in real time can be seen in Figure 2 The steps are shown and the corresponding explanations.

[0054] In some examples, if the operating state of the natural gas engine meets the preset conditions, it can be determined that the cause of the unstable idle speed of the natural gas engine may be due to the large zero-point leakage of the EGR valve. If the operating state of the natural gas engine does not meet the preset conditions, it can be determined that the cause of the unstable idle speed of the natural gas engine is not due to the large zero-point leakage of the EGR valve.

[0055] It can be understood that by determining whether the operating state of the natural gas engine meets the preset conditions based on the operating parameters of the natural gas engine obtained in real time, it is possible to 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.

[0056] S102: When the operating state meets a preset condition, a first speed fluctuation index is determined based on the engine speed of the natural gas engine within a first preset time.

[0057] Among them, the first preset time occurs after it is detected that the operating status meets the preset conditions, and the specific duration of the first preset time can be set by the technical staff according to the actual situation.

[0058] Optionally, when the running state meets the preset conditions, the implementation process of determining the first speed fluctuation index based on the engine speed of the natural gas engine within the first preset time can be referred to Figure 3 The steps are shown and the 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 driving duty cycle to a first calibration value, and the first calibration value is a negative value.

[0061] Optionally, if the first speed fluctuation index meets the preset range, a fault alarm of unstable engine idle speed and a second prompt message are generated, and 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 reason for the unstable engine idle speed is not the large zero-point leakage of the EGR valve. For this reason, a fault alarm of unstable engine idle speed and a second prompt message are generated to inform the owner to pay attention to check whether other components except the EGR valve and related components (such as the EGR valve position sensor) are faulty.

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

[0064] It should be noted that the purpose of adjusting the EGR valve drive duty cycle to the first calibration value is to reversely close the EGR valve, so as to further determine whether the main cause of the unstable engine idle speed is the large zero-point leakage of the EGR valve, prevent misjudgment, and thus improve the accuracy of diagnosis.

[0065] S104: 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.

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

[0067] Optionally, after the target event occurs and lasts for a second preset time, the implementation 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 seen in Figure 4 The steps are shown and the corresponding explanations.

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

[0069] The first prompt information is used to prompt that the reason for the unstable idle speed is that the zero-point leakage of the EGR valve is large.

[0070] Optionally, if the second speed fluctuation index does not meet the preset range, a fault alarm of unstable engine idle speed and a second prompt message are generated, and 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 idle speed of the natural gas engine is the large zero-point leakage of the EGR valve. If the second speed fluctuation index is within the preset range, it can be determined that the main cause of the unstable idle speed of the natural gas engine is not the large zero-point leakage of the EGR valve.

[0072] It can be understood that, by using the first speed fluctuation index and the second speed fluctuation index, it is possible to effectively identify whether the main cause of the unstable idle speed is a large zero-point leakage of the EGR valve, thereby achieving effective diagnosis of the unstable idle speed.

[0073] It should be noted that when the operating state of the natural gas engine meets the preset conditions, the EGR valve drive duty cycle is actively adjusted by executing the target event, and the EGR valve is further closed in the reverse direction. Through calculation (i.e., calculation of the first speed fluctuation index and the second speed fluctuation index) and judgment (i.e., comparison of the first speed fluctuation index and the second speed fluctuation index with the preset range respectively), it is confirmed whether the main cause of the unstable engine idling speed is the large zero-point leakage of the EGR valve. At the same time, the engine speed judgment confirmation time (i.e., the second preset time) before and after the active diagnosis is set to prevent misjudgment and further improve the diagnostic accuracy.

[0074] Optionally, after determining that the main reason for the unstable idle speed of the engine is the 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 a 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.

[0075] In some examples, the input-output control relationship can be expressed 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 EGR valve demand duty cycle) obtains the corresponding output Y (i.e., the EGR valve drive duty cycle) 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 the unstable engine idle speed is the large EGR valve zero-point leakage, the EGR valve drive duty cycle can be actively adjusted when the EGR valve demand duty cycle is 0 to ensure that the EGR valve is further closed at zero point and reduce the EGR valve leakage.

[0077] Combination Figure 2-Figure 4 The method shown in the embodiment of the present application can also be summarized as follows: Figure 5 The process shown includes steps 1 to 9 as shown below.

[0078] Step 1: Obtain operating parameters such as engine speed, idle speed setting value, 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 (ie, the running state of the natural gas engine) meets the preset conditions, wherein if the current state of the engine meets the preset conditions, execute step 3, otherwise return to execute step 1.

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

[0081] Step 4: Determine whether the average value N1 is within a preset range, wherein if the average value N1 is within the preset range, the diagnosis is terminated, otherwise, step 5 is executed.

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

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

[0084] Step 7: Determine whether the average value N2 is within a preset range, wherein if the average value N2 is within the preset range, execute step 8, otherwise terminate the diagnosis.

[0085] Step 8: The fault of large EGR valve leakage is reported, and it is suggested that the main reason for the unstable idle speed is large 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 when the EGR valve demand duty cycle is 0, the corresponding EGR driving duty cycle is B (ie, the second calibration value).

[0087] Based on the process shown in step 1 to step 9, by setting preset conditions under specific working conditions, automatic diagnosis of the speed unstable problem caused by large EGR valve zero-point leakage is achieved, thereby improving the accuracy of problem troubleshooting and shortening the troubleshooting time. At the same time, by actively modifying the EGR valve drive duty cycle corresponding to the EGR valve demand duty cycle at the EGR valve zero-point position after identifying the above problem, the EGR valve zero-point leakage problem is improved, which to a certain extent solves the problem of engine speed unstableness 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 process shown in S101-S105 above is based on the operating parameters of the natural gas engine and takes the first speed fluctuation index and the second speed fluctuation index as references to accurately diagnose whether the unstable idling speed of the natural gas engine is caused by a large zero-point leakage of the EGR valve, thereby effectively improving the efficiency and real-time performance of the diagnosis.

[0089] like Figure 2 As shown, it is a flow chart of another method for diagnosing unstable engine idle speed provided in an embodiment of the present application, including the steps shown below.

[0090] S201: Acquire the operating parameters of the natural gas engine in real time.

[0091] Among them, the operating condition parameters at least include idle state, neutral signal state, EGR system state, EGR valve required opening, EGR valve actual opening, and EGR valve drive duty cycle.

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

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

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

[0095] In some examples, if the EGR system has no fault, the EGR system status is no fault; if the EGR system has a fault, the EGR system status is a fault code corresponding to the fault.

[0096] In some examples, the EGR valve required opening is an opening command issued by the EGR system to the EGR valve, so that the EGR valve performs an opening control operation in response to the EGR valve required opening.

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

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

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

[0100] Among them, when the idle state is the idle condition, the neutral signal state is the vehicle stationary, the EGR system state is fault-free, the EGR valve required opening is 0, the EGR valve actual opening 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 idle operation state.

[0101] In some examples, when the idle 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 required 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 idle instability of the natural gas engine is caused by the large zero-point leakage of the EGR valve.

[0102] The process shown in S201-S202 above can use the operating parameters of the natural gas engine obtained in real time to determine whether the operating state of the natural gas engine meets the preset conditions, and can identify whether the natural gas engine is in an unstable idling operating 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 As shown, it is a flow chart of another method for diagnosing unstable engine idle speed provided in an embodiment of the present application, including the steps shown below.

[0104] S301: When the running state meets the preset conditions, real-time monitoring is performed on the number of times the engine speed of the natural gas engine deviates from the idle speed setting value within a first preset time, and the speed deviation amount corresponding to each deviation behavior.

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

[0106] In some examples, the idle speed setting value can be set by a technician according to actual conditions.

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

[0108] S302: Determine a first total deviation based on the accumulated sum of the absolute values ​​of the rotation speed deviations corresponding to each deviation behavior within the first preset time.

[0109] Among them, after monitoring 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: Determine a first speed fluctuation index based on a ratio between the first total deviation and the number of times the engine speed deviates from the idle speed setting value within a first preset time.

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

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

[0113] The process shown in S301-S303 above can determine the first speed fluctuation index based on the engine speed of the natural gas engine within the first preset time, thereby providing a favorable reference for diagnosing the unstable idle speed of the engine.

[0114] like Figure 4 As shown, it is a flow chart of another method for diagnosing unstable engine idle speed provided in an embodiment of the present application, including the steps shown below.

[0115] S401: After the target event occurs and lasts for a second preset time, real-time monitoring is performed on the number of times the engine speed of the natural gas engine deviates from the idle speed setting value within a third preset time, and the speed deviation amount corresponding to each deviation behavior.

[0116] The engine speed of the natural gas engine within the third preset time can be monitored in real time, and the multiple engine speeds obtained by monitoring can be compared with the idle speed setting value to obtain the number of times the engine speed deviates from the idle speed setting value within the third preset time, and the speed deviation amount corresponding to each deviation behavior.

[0117] S402: Determine a second total deviation based on the accumulated sum of the absolute values ​​of the rotation speed deviations corresponding to each deviation behavior within the third preset time.

[0118] Among them, after monitoring the speed deviation corresponding to each deviation behavior, multiple speed deviations with positive values ​​can be accumulated to obtain a third offset with a positive value, and multiple speed deviations with negative values ​​can be accumulated to obtain a fourth offset with a negative value.

[0119] S403: Determine a second speed fluctuation index based on a ratio between the second total deviation and the number of times the engine speed deviates from the idle setting value within a third preset time.

[0120] Among them, the ratio of the third offset to the number of multiple speed deviations with positive values ​​can be determined as the second positive fluctuation index, and the ratio of the fourth offset to the number of multiple speed deviations with negative values ​​can be determined as the second reverse fluctuation index. Based on the second positive fluctuation index and the second reverse fluctuation index, it is determined as the second speed fluctuation index.

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

[0122] The process shown in S401-S403 above can determine the second speed fluctuation index based on the engine speed of the natural gas engine within the third preset time, thereby providing a favorable reference for diagnosing the unstable idle speed of the engine.

[0123] like Figure 6 As shown, it is a schematic diagram of the architecture of a diagnostic device for unstable engine idle speed provided in an embodiment of the present application, including the units shown below.

[0124] The idle state determination unit 100 is used to determine whether the operating state of the natural gas engine meets a preset condition according to the operating parameters of the natural gas engine acquired in real time.

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

[0126] The first index determination unit 200 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 meets a preset condition.

[0127] Optionally, the first indicator determination unit 200 is specifically used for: when the operating state satisfies preset conditions, real-time monitoring of the number of times the engine speed of the natural gas engine deviates from the idle setting value within a first preset time, and the speed deviation corresponding to each deviation behavior; determining a first total deviation based on the cumulative sum of the absolute values ​​of the speed deviations corresponding to each deviation behavior within the first preset time; and determining a first speed fluctuation indicator based on the ratio of the first total deviation to the number of times the engine speed deviates from the idle setting value within the first preset time.

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

[0129] The second index determination unit 400 is used to determine a second speed fluctuation index 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 setting value within a third preset time, and the speed deviation corresponding to each deviation behavior; determine a second total deviation based on the cumulative sum of the absolute values ​​of the speed deviations corresponding to each deviation behavior within the third preset time; and determine a second speed fluctuation indicator based on the ratio of the second total deviation to the number of times the engine speed deviates from the idle setting value within the third preset time.

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

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

[0133] Optionally, the alarm prompt unit 500 is also used to: if the second speed fluctuation index does not meet the preset range, generate an engine idle speed unstable fault alarm and a second prompt message; the second prompt message is used to ensure that the EGR valve zero-point leakage volume 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 a 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 above-mentioned units, based on the operating parameters of the natural gas engine, combined with the first speed fluctuation index and the second speed fluctuation index as reference, accurately diagnose whether the unstable idling speed of the natural gas engine is caused by the large zero-point leakage of the EGR valve, thereby effectively improving the efficiency and real-time performance of the diagnosis.

[0136] The present application also provides a computer-readable storage medium, which includes a stored program, wherein the program executes the above-mentioned engine idle speed unstable diagnosis method provided by the present application.

[0137] The present application also provides a vehicle, including: a processor, a memory and a bus. The processor and the memory are connected via a bus, the memory is used to store a program, and the processor is used to run the program, wherein the engine idle speed unstable diagnosis method provided by the present application is executed when the program is run.

[0138] In addition, the functions described above in the embodiments of the present application may be at least partially performed by one or more hardware logic components. For example, without limitation, exemplary types of hardware logic components that may be used include: field programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), application specific standard products (ASSPs), systems on chips (SOCs), complex programmable logic devices (CPLDs), and the like.

[0139] Although several specific implementation details are included in the above discussion, these should not be interpreted as limiting the scope of the present application. Certain features described in the context of a separate embodiment can also be implemented in a single embodiment in combination. On the contrary, the various features described in the context of a single embodiment can also be implemented in multiple embodiments individually or in any suitable sub-combination.

[0140] The above description is only a preferred embodiment of the present application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of disclosure involved in the present application is not limited to the technical solution formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the above disclosed concept. For example, the above features are replaced with the technical features with similar functions disclosed in this application (but not limited to) by each other to form a technical solution.

Claims

1. A method for diagnosing unstable engine idling, characterized in that: include: Determining whether the operating state of the natural gas engine meets a preset condition according to the operating parameters of the natural gas engine acquired in real time; When the running state of the natural gas engine satisfies 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; The target event is: setting the EGR valve driving duty cycle to a first calibration value; 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; If the second speed fluctuation index meets the preset range, a fault alarm of large zero-point leakage of the EGR valve and a first prompt message are generated; The first prompt information is used to prompt that the cause of the unstable idle speed is a large amount of zero-point leakage of the EGR valve.

2. The method according to claim 1, characterized in that: According to the operating parameters of the natural gas engine acquired in real time, determining whether the operating state of the natural gas engine meets the preset conditions includes: Acquire the operating parameters of the natural gas engine in real time; the operating parameters at least include idle state, neutral signal state, EGR system state, EGR valve required opening, EGR valve actual opening, and EGR valve drive duty cycle; When the idle state is the idle condition, the neutral signal state is the vehicle stationary, the EGR system state is fault-free, the EGR valve required opening is 0, the EGR valve actual opening is 0, and the EGR valve drive duty cycle is less than or equal to 0, it is determined that the operating state of the natural gas engine meets the preset conditions.

3. The method according to claim 1, characterized in that When the running state of the natural gas engine 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 includes: When the running state of the natural gas engine meets the preset condition, real-time monitoring is performed on the number of times the engine speed of the natural gas engine deviates from the idle speed setting value within the first preset time, and the speed deviation amount corresponding to each deviation behavior; Determine a first total deviation based on the accumulated sum of the absolute values ​​of the rotation speed deviations corresponding to each deviation behavior within the first preset time; A first speed fluctuation index is determined based on a 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.

4. The method according to claim 1, characterized in that 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 includes: After the target event occurs and lasts for a second preset time, real-time monitoring is performed on the number of times the engine speed of the natural gas engine deviates from the idle speed setting value within a third preset time, and the speed deviation amount corresponding to each deviation behavior; Determine a second total deviation based on the accumulated sum of the absolute values ​​of the rotation speed deviations corresponding to each deviation behavior within the third preset time; A second speed fluctuation index is determined based on a ratio between the second total deviation and the number of times the engine speed deviates from the idle setting value within the third preset time.

5. The method according to claim 1, characterized in that After generating a fault alarm of a large zero-point leakage of the EGR valve and corresponding prompt information, the method further includes: 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 a second calibrated 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.

6. The method according to claim 1, characterized in that The method further comprises: If the first speed fluctuation index meets the preset range, a fault alarm of unstable engine idle speed 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. The method according to claim 1, characterized in that The method further comprises: If the second speed fluctuation index does not meet the preset range, a fault alarm of unstable engine idle speed and a second prompt message are generated; the second prompt message is used for the EGR valve zero-point leakage volume to meet the standard.

8. A diagnostic device for unstable engine idling, characterized in that: include: An idle state determination unit, used to determine whether the operating state of the natural gas engine meets a preset condition according to the operating parameters of the natural gas engine acquired in real time; a first index determination unit, configured to determine a first speed fluctuation index based on an engine speed of the natural gas engine within a first preset time when the running state of the natural gas engine satisfies the preset condition; A target event execution unit, configured to execute a target event if the first speed fluctuation index does not meet a preset range; The target event is: setting the EGR valve driving duty cycle to a first calibration value; A second index determination unit, configured to determine a second speed fluctuation index 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; An alarm prompting unit, configured to generate a fault alarm of a large zero-point gas leakage of the EGR valve and a first prompting message if the second speed fluctuation index meets the preset range; The first prompt information is used to prompt that the cause of the unstable idle speed is a large amount of zero-point leakage of the EGR valve.

9. A storage medium, characterized in that: The storage medium includes a stored program, wherein the program, when executed by a processor, executes the method for diagnosing unstable engine idle speed as described in any one of claims 1-7.

10. A vehicle, characterized in that: include: processor, memory, and bus; The processor is connected to the memory via the bus; The memory is used to store programs, and the processor is used to run programs, wherein the program, when run by the processor, executes the method for diagnosing unstable engine idle speed as described in any one of claims 1-7.

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