A method and device for diagnosing emission fault of hybrid engine

Abstract

The present application discloses a method and device for diagnosing emission faults of a hybrid engine, which collects the measurement value of a downstream nitrogen oxide sensor of the hybrid engine in real time. If the measurement value of the downstream nitrogen oxide sensor meets the fault detection condition, the selective catalytic reduction conversion efficiency of the hybrid engine at different preset ammonia nitrogen ratios under fixed working conditions is collected, and the selective catalytic reduction conversion efficiency at different preset ammonia nitrogen ratios is respectively compared with a pre-collected post-treatment crystallization efficiency curve and a pre-collected post-treatment aging efficiency curve to obtain a comparison result, and the fault type of the hybrid engine emission fault is determined according to the comparison result, wherein the fault type at least includes an emission fault type of excessive exhaust emissions caused by post-treatment crystallization or an emission fault type of excessive exhaust emissions caused by post-treatment aging, and the fault type of the hybrid engine emission fault is processed.

Description

Technical Field

[0001] The present application relates to the technical field of engine diagnosis, and more specifically, to a method and device for diagnosing emission faults of a hybrid engine. Background Art

[0002] As emission regulations become increasingly stringent, post-treatment is commonly used to meet engine emission requirements. However, when crystallization or aging occurs in the post-treatment, the actual conversion efficiency of the post-treatment will be reduced, resulting in excessive emissions, causing the vehicle to report a 1.2 failure or even causing the vehicle to be torque-limited. The vehicle reporting a 1.2 failure mainly refers to the problem of excessive nitrogen oxide (NOx) emissions in the vehicle emission system.

[0003] There is currently no active diagnostic method for the specific reasons for excessive NOx emissions in vehicle emission systems. The only way to solve the problem is for performance development engineers to analyze operating data based on market feedback or to find the cause of the fault on site during business trips. This results in a large waste of manpower and material resources, resulting in low efficiency in fault diagnosis of the reasons for excessive NOx emissions in vehicle emission systems.

[0004] Therefore, how to improve the efficiency of fault diagnosis for the cause of excessive NOx emissions in the vehicle emission system is a problem that needs to be solved urgently in this application. Summary of the invention

[0005] In view of this, the present application discloses a hybrid engine emission fault diagnosis method and device, aiming to reduce the fault risk of excessive nitrogen oxide emissions in the vehicle emission system and improve the efficiency of fault diagnosis of the cause of excessive nitrogen oxide emissions in the vehicle emission system.

[0006] In order to achieve the above purpose, the disclosed technical solution is as follows:

[0007] The first aspect of the present application discloses a method for diagnosing emission faults of a hybrid engine, the method comprising:

[0008] Real-time acquisition of measurements from the downstream NOx sensor of a hybrid engine;

[0009] If the measurement value of the downstream nitrogen oxide sensor meets the fault detection condition, collecting the selective catalytic reduction conversion efficiency of the hybrid engine at different preset ammonia nitrogen ratios under fixed working conditions;

[0010] The selective catalytic reduction conversion efficiency of different preset ammonia nitrogen ratios is compared with the pre-collected post-treatment crystallization efficiency curve and the pre-collected post-treatment aging efficiency curve to obtain a comparison result;

[0011] Determining the fault type of the hybrid engine emission fault according to the comparison result; wherein the fault type at least includes the emission fault type of excessive exhaust gas emissions caused by post-treatment crystallization or the emission fault type of excessive exhaust gas emissions caused by post-treatment aging;

[0012] Process the fault types of hybrid engine emission faults.

[0013] Preferably, if the measured value of the downstream nitrogen oxide sensor meets the fault detection condition, collecting the selective catalytic reduction conversion efficiency of the hybrid engine at different preset ammonia nitrogen ratios under fixed working conditions includes:

[0014] If the measurement value of the downstream nitrogen oxygen sensor is greater than a preset threshold, and the time during which the measurement value of the downstream nitrogen oxygen sensor is greater than the preset threshold is greater than a preset time, it is determined that the measurement value of the downstream nitrogen oxygen sensor meets the fault detection condition;

[0015] When the measurement value of the downstream nitrogen oxide sensor meets the fault detection condition, adjusting the operating condition of the hybrid engine to a fixed operating condition in a preset manner;

[0016] Under fixed operating conditions of the hybrid engine, the urea pump is controlled to clean the ammonia storage on the selective catalytic reduction carrier, and the upstream nitrogen oxide sensor measurement value is obtained after a preset time interval;

[0017] Injection is performed according to different preset ammonia nitrogen ratios to obtain downstream nitrogen oxide sensor measurement values ​​at the end of each injection stage;

[0018] The upstream nitrogen oxide sensor measurement value is calculated with the downstream nitrogen oxide sensor measurement value at the end of each injection phase to obtain the selective catalytic reduction conversion efficiency of the hybrid engine at different preset ammonia nitrogen ratios under fixed working conditions.

[0019] Preferably, the selective catalytic reduction conversion efficiency at different preset ammonia nitrogen ratios is compared with the pre-collected post-treatment crystallization efficiency curve and the pre-collected post-treatment aging efficiency curve to obtain a comparison result, including:

[0020] Searching for post-treatment crystallization efficiency curves according to different preset ammonia nitrogen ratios to obtain reference efficiencies of various post-treatment crystallizations corresponding to different preset ammonia nitrogen ratios, and searching for post-treatment aging efficiency curves according to various preset ammonia nitrogen ratios to obtain reference efficiencies of various post-treatment agings corresponding to different preset ammonia nitrogen ratios;

[0021] Obtaining a first correlation coefficient according to the reference efficiencies of the post-treatment crystals corresponding to the different preset ammonia-nitrogen ratios and the selective catalytic reduction conversion efficiencies of the different preset ammonia-nitrogen ratios, and calculating a first absolute value of the difference between the first correlation coefficient and the preset value;

[0022] According to the reference efficiencies of the post-treatment aging corresponding to the different preset ammonia-nitrogen ratios and the selective catalytic reduction conversion efficiencies of the different preset ammonia-nitrogen ratios, a second correlation coefficient is obtained, and a second absolute value of the difference between the second correlation coefficient and the preset value is calculated;

[0023] Determine whether the first absolute value is less than or equal to the second absolute value;

[0024] If the first absolute value is less than or equal to the second absolute value, a first comparison result is obtained;

[0025] If the first absolute value is greater than the second absolute value, a second comparison result is obtained.

[0026] Preferably, determining the fault type of the hybrid engine emission fault according to the comparison result includes:

[0027] If the comparison result is the first comparison result, it is determined that the fault type of the hybrid engine emission fault is an emission fault type of excessive exhaust emissions caused by post-treatment crystallization;

[0028] If the comparison result is the second comparison result, it is determined that the fault type of the hybrid engine emission fault is an emission fault type of excessive exhaust emissions caused by after-treatment aging.

[0029] Preferably, the processing of the fault type of the hybrid engine emission fault includes:

[0030] If the fault type of the hybrid engine emission fault is an emission fault type of excessive exhaust emissions caused by post-processing crystallization, regeneration is triggered to clear the crystallization to repair the emission fault;

[0031] If the fault type of the hybrid engine emission fault is an emission fault type of excessive exhaust emissions caused by after-treatment aging, a prompt message is generated.

[0032] A second aspect of the present application discloses a hybrid engine emission fault diagnosis device, the device comprising:

[0033] A first acquisition unit, used for acquiring the measurement value of a downstream nitrogen oxygen sensor of the hybrid engine in real time;

[0034] A second collection unit is used to collect the selective catalytic reduction conversion efficiency of the hybrid engine at different preset ammonia nitrogen ratios under fixed working conditions if the measurement value of the downstream nitrogen oxide sensor meets the fault detection condition;

[0035] A comparison unit is used to compare the selective catalytic reduction conversion efficiency of different preset ammonia nitrogen ratios with the pre-collected post-treatment crystallization efficiency curve and the pre-collected post-treatment aging efficiency curve to obtain a comparison result;

[0036] A determination unit, configured to determine the fault type of the hybrid engine emission fault according to the comparison result; wherein the fault type at least includes the emission fault type of excessive exhaust gas emissions caused by post-treatment crystallization or the emission fault type of excessive exhaust gas emissions caused by post-treatment aging;

[0037] The processing unit is used for processing the fault type of hybrid engine emission fault.

[0038] Preferably, the second acquisition unit includes:

[0039] A first determination module, configured to determine that the measurement value of the downstream nitrogen oxygen sensor meets a fault detection condition if the measurement value of the downstream nitrogen oxygen sensor is greater than a preset threshold and the time during which the measurement value of the downstream nitrogen oxygen sensor is greater than the preset threshold is greater than a preset time;

[0040] An adjustment module, configured to adjust the operating condition of the hybrid engine to a fixed operating condition in a preset manner when the measurement value of the downstream nitrogen oxide sensor meets the fault detection condition;

[0041] A control acquisition module is used to control the urea pump to clean the ammonia storage on the selective catalytic reduction carrier under the fixed working condition of the hybrid engine, and obtain the measurement value of the upstream nitrogen oxide sensor after a preset time interval;

[0042] A first acquisition module is used for performing injection according to different preset ammonia nitrogen ratios to obtain a downstream nitrogen oxygen sensor measurement value at the end time of each injection stage;

[0043] The calculation module is used to calculate the upstream nitrogen oxide sensor measurement value and the downstream nitrogen oxide sensor measurement value at the end time of each injection stage respectively, so as to obtain the selective catalytic reduction conversion efficiency of the hybrid engine under fixed working conditions with different preset ammonia nitrogen ratios.

[0044] Preferably, the comparison unit comprises:

[0045] A search module is used to search for a post-treatment crystallization efficiency curve according to different preset ammonia nitrogen ratios to obtain reference efficiencies of each post-treatment crystallization corresponding to different preset ammonia nitrogen ratios, and to search for a post-treatment aging efficiency curve according to each preset ammonia nitrogen ratio to obtain reference efficiencies of each post-treatment aging corresponding to different preset ammonia nitrogen ratios;

[0046] A first acquisition calculation module is used to obtain a first correlation coefficient according to the reference efficiency of each post-treatment crystallization corresponding to the different preset ammonia-nitrogen ratios and the selective catalytic reduction conversion efficiency of the different preset ammonia-nitrogen ratios, and calculate a first absolute value of the difference between the first correlation coefficient and the preset value;

[0047] A second acquisition calculation module is used to obtain a second correlation coefficient according to the reference efficiency of each post-treatment aging corresponding to the different preset ammonia nitrogen ratios and the selective catalytic reduction conversion efficiency of the different preset ammonia nitrogen ratios, and calculate a second absolute value of the difference between the second correlation coefficient and the preset value;

[0048] A judging module, used for judging whether the first absolute value is less than or equal to the second absolute value;

[0049] A second acquisition module, configured to obtain a first comparison result if the first absolute value is less than or equal to the second absolute value;

[0050] The third acquisition module is used to obtain a second comparison result if the first absolute value is greater than the second absolute value.

[0051] Preferably, the determining unit includes:

[0052] a second determination module, configured to determine, if the comparison result is the first comparison result, that the fault type of the hybrid engine emission fault is an emission fault type of excessive exhaust emissions caused by post-treatment crystallization;

[0053] The third determination module is used to determine that the fault type of the hybrid engine emission fault is an emission fault type of excessive exhaust emissions caused by after-treatment aging if the comparison result is the second comparison result.

[0054] Preferably, the processing unit comprises:

[0055] A repair module, for triggering regeneration and clearing crystals to repair the emission fault if the fault type of the hybrid engine emission fault is an emission fault type of excessive exhaust emissions caused by post-treatment crystals;

[0056] The generating module is used to generate a prompt message if the fault type of the hybrid engine emission fault is the exhaust gas emission exceeding the standard caused by the aging of the post-treatment.

[0057] It can be known from the above technical scheme that the present application discloses a method and device for diagnosing emission faults of a hybrid engine, which collects the measurement value of a downstream nitrogen oxide sensor of the hybrid engine in real time. If the measurement value of the downstream nitrogen oxide sensor meets the fault detection condition, the selective catalytic reduction conversion efficiency of the hybrid engine at different preset ammonia nitrogen ratios under fixed working conditions is collected, and the selective catalytic reduction conversion efficiency at different preset ammonia nitrogen ratios is respectively compared with the pre-collected post-treatment crystallization efficiency curve and the pre-collected post-treatment aging efficiency curve to obtain the comparison result, and the fault type of the hybrid engine emission fault is determined according to the comparison result, wherein the fault type at least includes the emission fault type of excessive exhaust emissions caused by post-treatment crystallization or the emission fault type of excessive exhaust emissions caused by post-treatment aging, and the fault type of the hybrid engine emission fault is processed.

[0058] Through the above scheme, in the process of fault diagnosis of the cause of excessive NOx emission in the vehicle emission system, there is no need for performance development engineers to analyze the operation data or to find the cause of the fault on site by business trip to solve the problem. It is only necessary to actively trigger the high emission fault cause diagnosis function after the exhaust emission is detected to be high and lasts for a certain period of time, that is, the measurement value of the downstream nitrogen oxide sensor meets the fault detection condition, and adjust the engine to a fixed working condition by using the battery charging and discharging of the hybrid engine, collect the selective catalytic reduction conversion efficiency under different ammonia nitrogen ratio injection states under the fixed working condition, and compare the correlation with the efficiency characteristic curves of the post-treatment crystallization state and the post-treatment aging state, so as to automatically diagnose the specific cause and fault type of excessive nitrogen oxide emission in the vehicle emission system, and after identifying the specific cause and fault type, repair the vehicle fault or generate a prompt message to prompt the driver to go to the service station for inspection as soon as possible, so as to ensure that the nitrogen oxide emission in the vehicle emission system does not exceed the limit value, reduce the fault risk of excessive nitrogen oxide emission in the vehicle emission system, and improve the efficiency of fault diagnosis of the cause of excessive nitrogen oxide emission in the vehicle emission system. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] 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 embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0060] Figure 1 A schematic flow chart of a hybrid engine emission fault diagnosis method disclosed in an embodiment of the present application;

[0061] Figure 2It is a schematic diagram of the crystal state-conversion efficiency characteristic curve disclosed in the examples of this application;

[0062] Figure 3 It is a schematic diagram of the aging state-conversion efficiency characteristic curve disclosed in the embodiment of this application;

[0063] Figure 4 A schematic flow chart of another hybrid engine emission fault diagnosis method disclosed in an embodiment of the present application;

[0064] Figure 5 This is a schematic diagram of the structure of a hybrid engine emission fault diagnosis device disclosed in an embodiment of the present application. DETAILED DESCRIPTION

[0065] 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.

[0066] In this application, the terms "comprises", "comprising" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising 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 further restrictions, an element defined by the sentence "comprising a ..." does not exclude the presence of other identical elements in the process, method, article or device comprising the element.

[0067] As can be seen from the background technology, there is currently no relevant active diagnosis method for the specific reasons for excessive NOx emissions in vehicle emission systems. It can only be solved by performance development engineers analyzing operating data or finding the cause of the fault on site through business trips after market feedback, which causes a lot of waste of manpower and material resources, resulting in low efficiency in fault diagnosis of the reasons for excessive NOx emissions in vehicle emission systems. Therefore, how to improve the efficiency of fault diagnosis of the reasons for excessive NOx emissions in vehicle emission systems is a problem that urgently needs to be solved in this application.

[0068] In order to solve the above problems, the present application discloses a hybrid engine emission fault diagnosis method and device. In the process of fault diagnosis of the cause of excessive NOx emission in the vehicle emission system, there is no need for performance development engineers to analyze the operation data or find the cause of the fault on site by going on business trips to solve the problem. It is only necessary to detect that the exhaust emission is high and lasts for a certain period of time, that is, the measurement value of the downstream nitrogen oxide sensor meets the fault detection condition, and actively trigger the high emission fault cause diagnosis function, adjust the engine to a fixed working condition by using the battery charging and discharging of the hybrid engine, collect the selective catalytic reduction conversion efficiency under different ammonia nitrogen ratio injection states under the fixed working condition, and compare the correlation with the efficiency characteristic curves of the post-treatment crystallization state and the post-treatment aging state, so as to automatically diagnose the specific cause and fault type of excessive nitrogen oxide emission in the vehicle emission system, identify the specific cause and fault type, repair the vehicle fault or generate prompt information to prompt the driver to go to the service station for repair as soon as possible, so as to ensure that the nitrogen oxide emission in the vehicle emission system does not exceed the limit value, reduce the fault risk of excessive nitrogen oxide emission in the vehicle emission system, and improve the efficiency of fault diagnosis of the cause of excessive nitrogen oxide emission in the vehicle emission system. The specific implementation method is specifically described by the following embodiments.

[0069] refer to Figure 1 FIG. 1 is a flow chart of a hybrid engine emission fault diagnosis method disclosed in an embodiment of the present application. The hybrid engine emission fault diagnosis method mainly includes the following steps:

[0070] S101: Collecting the measurement value of the downstream nitrogen oxide sensor of the hybrid engine in real time.

[0071] A hybrid engine is a powertrain that combines a traditional internal combustion engine with an electric motor to improve fuel efficiency, reduce emissions and enhance vehicle performance.

[0072] It should be noted that in the process of collecting the measurement values ​​of the downstream nitrogen oxide sensor (i.e., downstream NOx sensor) of the hybrid engine, the downstream nitrogen oxide sensor of the hybrid engine is calibrated regularly to ensure that it can accurately feedback the conversion efficiency of the downstream nitrogen oxide sensor, thereby improving the accuracy of collecting the measurement values ​​of the downstream nitrogen oxide sensor of the hybrid engine.

[0073] S102: If the measurement value of the downstream nitrogen oxide sensor meets the fault detection condition, the selective catalytic reduction (SCR) conversion efficiency of the hybrid engine at different preset ammonia nitrogen ratios under fixed operating conditions is collected.

[0074] It should be noted that if the measurement value of the downstream nitrogen oxide sensor is greater than a preset threshold, and the time during which the measurement value of the downstream nitrogen oxide sensor is greater than the preset threshold is greater than the preset time, it is determined that the measurement value of the downstream nitrogen oxide sensor meets the fault detection condition.

[0075] If the measurement value of the downstream nitrogen oxide sensor is less than or equal to a preset threshold, or the time during which the measurement value of the downstream nitrogen oxide sensor is less than or equal to the preset threshold is greater than a preset time, it is determined that the measurement value of the downstream nitrogen oxide sensor does not meet the fault detection condition.

[0076] Among them, the preset threshold and preset time are set according to actual conditions, and this application does not make specific limitations.

[0077] In S102, if the measurement value of the downstream nitrogen oxide sensor meets the fault detection condition, the fault diagnosis function is triggered, and the hybrid engine is adjusted to a fixed operating condition using a preset method (such as a battery charging and discharging method).

[0078] The fixed operating condition is a fixed operating condition where the SCR temperature is 300° C. In the performance development stage of the hybrid engine, a high efficiency point of the hybrid engine is selected, and under this fixed operating condition, the exhaust temperature is good and the conversion efficiency is high.

[0079] The main function of SCR is to use NH3 decomposed by urea to carry out catalytic reduction reaction with NOx in the exhaust gas to reduce the emission level of NOx in the exhaust gas to meet regulatory requirements.

[0080] The ammonia nitrogen ratio refers to the molar ratio of NH3 in urea to NOx in the engine exhaust. Usually, the actual injection amount of urea is calculated by controlling the ammonia nitrogen ratio so that the engine's NOx emission level meets the standard.

[0081] The expression of SCR conversion efficiency is as follows:

[0082] (NOx upstream of SCR - NOx downstream of SCR) / NOx upstream of SCR*100%.

[0083] Specifically, if the measurement value of the downstream nitrogen oxide sensor meets the fault detection condition, the process of collecting the SCR conversion efficiency of the hybrid engine under different preset ammonia nitrogen ratios under fixed working conditions is shown in A1-A4.

[0084] A1: If the measurement value of the downstream nitrogen oxide sensor is greater than a preset threshold, and the time during which the measurement value of the downstream nitrogen oxide sensor is greater than the preset threshold is greater than a preset time, it is determined that the measurement value of the downstream nitrogen oxide sensor meets the fault detection condition.

[0085] Among them, if the measurement value of the downstream nitrogen oxide sensor is greater than the preset threshold, and the time when the measurement value of the downstream nitrogen oxide sensor is greater than the preset threshold is greater than the preset time, it indicates that the measurement value of the downstream NOx sensor is large and lasts for a certain period of time, triggering the fault diagnosis function.

[0086] A2: When the measurement value of the downstream nitrogen oxide sensor meets the fault detection condition, the operating condition of the hybrid engine is adjusted to a fixed operating condition by a preset method.

[0087] The preset mode refers to a mode of charging and discharging the battery. After the fault diagnosis function is triggered, the operating condition of the hybrid engine is adjusted to a fixed operating condition through charging and discharging the battery.

[0088] A3: Under fixed operating conditions of the hybrid engine, the urea pump is controlled to clean the ammonia storage on the SCR carrier, and the upstream nitrogen oxide sensor measurement value (N0) is obtained after a preset time interval.

[0089] The preset interval duration can be 2 minutes, 3 minutes, etc. The preset interval duration is set according to actual conditions and this application does not make any specific limitations.

[0090] For example, the urea pump is controlled to stop spraying for 2 minutes to clean the ammonia storage on the SCR carrier, and N0 is recorded after 2 minutes.

[0091] It should be noted that ammonia storage refers to the amount of ammonia stored on the SCR carrier, which can convert a portion of nitrogen oxides. Since the subsequent comparison of the post-treatment crystallization efficiency curve (cur1) and the post-treatment aging efficiency curve (cur2) were collected without ammonia storage, it is necessary to clean the ammonia storage to eliminate the impact of the ammonia storage in the SCR carrier on the actual conversion efficiency.

[0092] The diagnostic principle of this solution is to diagnose the specific cause of high emissions based on the efficiency characteristic curves of the post-treatment crystallization state and the post-treatment aging state. Install a box for the post-treatment crystallization state and a box for the post-treatment aging state respectively, collect the post-treatment crystallization efficiency curve of the box for the post-treatment crystallization state of the hybrid engine under the fixed working condition, and collect the post-treatment aging efficiency curve of the box for the post-treatment aging state of the hybrid engine under the fixed working condition. Figure 2 and Figure 3 As shown, the conversion efficiency characteristic curves in the crystallized state and the aged state are significantly different. The cause of high emission faults can be identified by calculating the correlation coefficient between the two characteristic curves. Figure 2 It is a schematic diagram of the crystal state-conversion efficiency characteristic curve. Figure 3 It is a schematic diagram of the aging state-conversion efficiency characteristic curve.

[0093] Figure 2In the figure, the horizontal axis is the ammonia nitrogen ratio (ANR), and the vertical axis is the conversion efficiency in the crystalline state.

[0094] Figure 3 In the figure, the horizontal axis is the ammonia nitrogen ratio (ANR), and the vertical axis is the conversion efficiency under the aged state.

[0095] The crystallization state-conversion efficiency characteristic curve and the aging state-conversion efficiency characteristic curve are determined by collecting the ANR of the engine under the fixed operating conditions and the corresponding conversion efficiencies.

[0096] A4: Injection is performed according to different preset ammonia nitrogen ratios to obtain the downstream nitrogen oxide sensor measurement value at the end of each injection stage.

[0097] Among them, different preset ammonia-nitrogen ratios include R1=0.7, R2=0.8, R3=0.9, and R4=1.0.

[0098] According to the preset ammonia nitrogen ratio R1=0.7, the injection phase lasts for 2 minutes, and the downstream nitrogen oxide sensor measurement value N1 at the end of this injection phase is recorded; according to the preset ammonia nitrogen ratio R2=0.8, the injection phase lasts for 2 minutes, and the downstream nitrogen oxide sensor measurement value N2 at the end of this injection phase is recorded; according to the preset ammonia nitrogen ratio R3=0.9, the injection phase lasts for 2 minutes, and the downstream nitrogen oxide sensor measurement value N3 at the end of this injection phase is recorded; according to the preset ammonia nitrogen ratio R1=1.0, the injection phase lasts for 2 minutes, and the downstream nitrogen oxide sensor measurement value N4 at the end of this injection phase is recorded.

[0099] A5: N0 is calculated with the downstream nitrogen oxide sensor measurement value at the end of each injection phase to obtain the SCR conversion efficiency of the hybrid engine at different preset ammonia nitrogen ratios under fixed operating conditions.

[0100] The expression for calculating the SCR conversion efficiency of the hybrid engine under fixed working conditions with different preset ammonia nitrogen ratios is as follows:

[0101] F1=(N0-N1) / N0;

[0102] F2=(N0-N2) / N0;

[0103] F3=(N0-N3) / N0;

[0104] F4=(N0-N4) / N0.

[0105] Among them, F1 is the SCR conversion efficiency corresponding to the ammonia nitrogen ratio R1; F2 is the SCR conversion efficiency corresponding to the ammonia nitrogen ratio R2; F3 is the SCR conversion efficiency corresponding to the ammonia nitrogen ratio R3; F4 is the SCR conversion efficiency corresponding to the ammonia nitrogen ratio R4; N0 is the measurement value of the upstream nitrogen oxides sensor; N1 is the measurement value of the downstream nitrogen oxides sensor at the end of the injection phase of the ammonia nitrogen ratio R1; N2 is the measurement value of the downstream nitrogen oxides sensor at the end of the injection phase of the ammonia nitrogen ratio R2; N3 is the measurement value of the downstream nitrogen oxides sensor at the end of the injection phase of the ammonia nitrogen ratio R3; N4 is the measurement value of the downstream nitrogen oxides sensor at the end of the injection phase of the ammonia nitrogen ratio R4.

[0106] S103: performing correlation comparison on the SCR conversion efficiency of different preset ammonia nitrogen ratios with the pre-collected post-treatment crystallization efficiency curve (i.e., crystallization state-conversion efficiency characteristic curve) and the pre-collected post-treatment aging efficiency curve (i.e., aging state-conversion efficiency characteristic curve) to obtain comparison results.

[0107] The specific process of obtaining the comparison result is shown in B1-B6.

[0108] B1: According to different preset ammonia nitrogen ratios, the post-processing crystallization efficiency curve is searched to obtain the reference efficiency of each post-processing crystallization corresponding to the different preset ammonia nitrogen ratios, and according to each preset ammonia nitrogen ratio, the post-processing aging efficiency curve is searched to obtain the reference efficiency of each post-processing aging corresponding to the different preset ammonia nitrogen ratios.

[0109] Among them, R1, R2, R3, and R4 are searched respectively. Figure 2 The reference efficiency Fa1, Fa2, Fa3, and Fa4 of each post-processing crystallization can be obtained from cur1. For example, according to R1=0.7, its reference efficiency Fa1 is 50; R2=0.8, its reference efficiency Fa2 is 62; R3=0.9, its reference efficiency Fa3 is 75; R4=1.0, its reference efficiency Fa4 is 85.

[0110] The reference efficiencies Fb1, Fb2, Fb3, and Fb4 of the post-processing aging of cur2 are found by R1, R2, R3, and R4 respectively.

[0111] B2: Obtain a first correlation coefficient based on the reference efficiency of each post-treatment crystallization corresponding to different preset ammonia-nitrogen ratios and the selective catalytic reduction conversion efficiency of different preset ammonia-nitrogen ratios, and calculate a first absolute value of the difference between the first correlation coefficient and the preset value.

[0112] Among them, the reference efficiency of each post-processing crystallization corresponding to different preset ammonia-nitrogen ratios is the array [Fa1, Fa2, Fa3, Fa4].

[0113] The default value may be 1.

[0114] The formula for calculating a of the array [F1, F2, F3, F4] and the array [Fa1, Fa2, Fa3, Fa4] is shown in formula (1):

[0115] (1)

[0116] in, ; .

[0117] Calculate the first absolute value of the difference between a and 1, that is, |a-1|.

[0118] B3: According to the reference efficiencies of various post-treatment aging corresponding to different preset ammonia nitrogen ratios and the selective catalytic reduction (SCR) conversion efficiencies at different preset ammonia nitrogen ratios, a second correlation coefficient (b) is obtained, and a second absolute value of the difference between the second correlation coefficient and the preset value is calculated.

[0119] The reference efficiency of each post-treatment aging corresponding to different preset ammonia-nitrogen ratios is an array [Fb1, Fb2, Fb3, Fb4].

[0120] The specific calculation formula for b of the array [F1, F2, F3, F4] and the array [Fb1, Fb2, Fb3, Fb4] is shown in formula (2).

[0121] (2)

[0122] in, ; .

[0123] Calculate the second absolute value of the difference between b and 1, that is, |b-1|.

[0124] B4: Determine whether the first absolute value is less than or equal to the second absolute value.

[0125] Among them, it is determined whether |a-1| is less than or equal to |b-1|.

[0126] B5: If the first absolute value is less than or equal to the second absolute value, a first comparison result is obtained.

[0127] If |a-1| is less than or equal to |b-1|, a first comparison result is obtained. The first comparison result is used to indicate that |a-1| is less than or equal to |b-1|.

[0128] B6: If the first absolute value is greater than the second absolute value, a second comparison result is obtained.

[0129] If |a-1| is greater than |b-1|, a second comparison result is obtained. The first comparison result is used to indicate that |a-1| is greater than |b-1|.

[0130] S104: Determine the fault type of the hybrid engine emission fault according to the comparison result; wherein the fault type at least includes the emission fault type of excessive exhaust emissions caused by after-treatment crystallization or the emission fault type of excessive exhaust emissions caused by after-treatment aging.

[0131] In S104, if the comparison result is the first comparison result, it is determined that the fault type of the hybrid engine emission fault is the emission fault type of excessive exhaust emissions caused by after-treatment crystallization; if the comparison result is the second comparison result, it is determined that the fault type of the hybrid engine emission fault is the emission fault type of excessive exhaust emissions caused by after-treatment aging.

[0132] S105: Processing the fault type of the hybrid engine emission fault.

[0133] If the fault type of the hybrid engine emission fault is an emission fault type of excessive exhaust emissions caused by post-treatment crystallization, regeneration and removal of crystallization are triggered to repair the emission fault. For example, if |a-1| is less than or equal to |b-1|, it is determined that the fault type of the hybrid engine emission fault is an emission fault type of excessive exhaust emissions caused by post-treatment crystallization, that is, it is determined that post-treatment crystallization is the cause of high exhaust emissions, and regeneration and removal of crystallization are triggered.

[0134] If the fault type of the hybrid engine emission fault is the exhaust emission exceeding the standard caused by the aging of the aftertreatment, a prompt message is generated. For example, if |a-1| is greater than |b-1|, it is determined that the fault type of the hybrid engine emission fault is the exhaust emission exceeding the standard caused by the aging of the aftertreatment, that is, the aging of the aftertreatment is the cause of the high exhaust gas, and a prompt message is generated to prompt the driver to go to the service station for repair as soon as possible.

[0135] This solution can actively trigger the high emission fault cause diagnosis function when the tail emissions are detected to be continuously high, use battery charging and discharging to adjust the engine to a fixed operating condition, collect the conversion efficiency under different ammonia nitrogen ratio injection states under the operating point, and compare the correlation with the efficiency characteristic curves of the post-treatment crystallization state and the post-treatment aging state, diagnose the specific cause of the high emissions, and after identifying the specific cause, repair the vehicle fault or prompt the driver to go to the service station for inspection as soon as possible, so as to ensure that the emissions do not exceed the limit and reduce the risk of the vehicle reporting a 1.2 fault (i.e., a fault mainly involving excessive NOx emissions in the vehicle emission system).

[0136] When a vehicle's SCR system reports an excessive NOx emissions fault, it typically means that the vehicle's aftertreatment system needs to take action to restore SCR conversion efficiency.

[0137] This solution uses the hybrid engine to adjust the engine's operating condition to a fixed condition by charging and discharging the battery during the vehicle's driving. The exhaust temperature and gas volume in this condition are relatively fixed. The conversion efficiency under different ammonia nitrogen ratios is collected in sequence through urea injection control, and the correlation calculation is performed with the efficiency characteristic curves of the post-treatment crystallization state and the post-treatment aging state to diagnose the specific cause of high emissions, thereby achieving the purpose of diagnosis.

[0138] In order to facilitate the understanding of the specific process of the hybrid engine emission fault diagnosis method, combined with Figure 4 Let's take an example:

[0139] Figure 4 In the process, when the downstream NOx sensor measurement value is detected to be large and lasts for a certain period of time, the fault diagnosis function is triggered, and the engine is adjusted to a fixed operating condition by using battery charging and discharging;

[0140] Control the urea pump to stop spraying for 2 minutes to clean the ammonia storage on the SCR carrier, and record the upstream nitrogen oxide sensor measurement value N0 after 2 minutes;

[0141] The ammonia nitrogen ratios are set to R1=0.7, R2=0.8, R3=0.9, and R4=1.0, respectively. Each stage lasts for 2 minutes. The downstream nitrogen oxide sensor measurement values ​​N1, N2, N3, and N4 are recorded at the end of each stage.

[0142] Calculate the conversion efficiency in the four stages respectively:

[0143] F1=(N0-N1) / N0; F2=(N0-N2) / N0; F3=(N0-N3) / N0; F4=(N0-N4) / N0;

[0144] Search the post-processing crystallization efficiency curve cur1 by R1, R2, R3, R4 to obtain the reference efficiency Fa1, Fa2, Fa3, Fa4; calculate the correlation coefficient a between the array [F1, F12, F13, F14] and the array [Fa1, Fa2, Fa3, Fa4], and find the absolute value la-1l of the difference between the correlation coefficient a and 1;

[0145] The post-processing aging efficiency curve cur2 is searched by R1, R2, R3, and R4 to obtain the reference efficiency Fb1, Fb2, Fb3, and Fb4 respectively; the correlation coefficient between the array [F1, F12, F13, and F14] and the array [Fa1, Fa2, Fa3, and Fa4] is calculated, and the absolute value lb-1l of the difference between the correlation coefficient b and 1 is obtained;

[0146] Determine whether |a-1| is less than or equal to |b-1|. If |a-1| is less than or equal to |b-1|, then determine that post-processing crystallization is the cause of high tail discharge, and trigger regeneration to remove crystallization;

[0147] If |a-1| is greater than |b-1|, it is judged that the aging of the post-processing is the cause of the high tail emissions, and the driver is prompted to go to the service station for maintenance as soon as possible.

[0148] In the embodiment of the present application, in the process of fault diagnosis of the cause of excessive NOx emission in the vehicle emission system, there is no need for the performance development engineer to analyze the operation data or to find the cause of the fault on site by way of business trip, thereby avoiding a large amount of waste of manpower and material resources. It is only necessary to actively trigger the high emission fault diagnosis function after detecting that the exhaust emission is high and lasts for a certain period of time, that is, the measured value of the downstream nitrogen oxide sensor meets the fault detection condition, and adjust the engine to a fixed working condition by using the battery charging and discharging of the hybrid engine, collect the selective catalytic reduction conversion efficiency under the fixed working condition under different ammonia nitrogen ratio injection states, and compare the correlation with the efficiency characteristic curves of the post-treatment crystallization state and the post-treatment aging state, so as to automatically diagnose the specific cause and fault type of excessive nitrogen oxide emission in the vehicle emission system, and after identifying the specific cause and fault type, repair the vehicle fault or generate prompt information to prompt the driver to go to the service station for repair as soon as possible, so as to ensure that the nitrogen oxide emission in the vehicle emission system does not exceed the limit value, reduce the fault risk of excessive nitrogen oxide emission in the vehicle emission system, and improve the efficiency of fault diagnosis of the cause of excessive nitrogen oxide emission in the vehicle emission system.

[0149] Based on the above embodiments Figure 1 A hybrid engine emission fault diagnosis method is disclosed, and an embodiment of the present application also discloses a hybrid engine emission fault diagnosis device, such as Figure 5 As shown, the hybrid engine emission fault diagnostic device includes:

[0150] A first acquisition unit 501 is used to acquire the measurement value of the downstream nitrogen oxygen sensor of the hybrid engine in real time;

[0151] The second collection unit 502 is used to collect the selective catalytic reduction conversion efficiency of the hybrid engine at different preset ammonia nitrogen ratios under fixed working conditions if the measurement value of the downstream nitrogen oxide sensor meets the fault detection condition;

[0152] The comparison unit 503 is used to compare the selective catalytic reduction conversion efficiency of different preset ammonia nitrogen ratios with the pre-collected post-treatment crystallization efficiency curve and the pre-collected post-treatment aging efficiency curve to obtain a comparison result;

[0153] The determination unit 504 is used to determine the fault type of the hybrid engine emission fault according to the comparison result; wherein the fault type at least includes the emission fault type of the exhaust gas emission exceeding the standard caused by the after-treatment crystallization or the emission fault type of the exhaust gas emission exceeding the standard caused by the after-treatment aging;

[0154] The processing unit 505 is used to process the fault type of the hybrid engine emission fault.

[0155] Furthermore, the second acquisition unit 502 includes:

[0156] A first determination module, configured to determine that the measurement value of the downstream nitrogen oxide sensor meets a fault detection condition if the measurement value of the downstream nitrogen oxide sensor is greater than a preset threshold value and the time during which the measurement value of the downstream nitrogen oxide sensor is greater than the preset threshold value is greater than a preset time;

[0157] An adjustment module, used for adjusting the operating condition of the hybrid engine to a fixed operating condition by a preset method when the measurement value of the downstream nitrogen oxide sensor meets the fault detection condition;

[0158] A control acquisition module is used to control the urea pump to clean the ammonia storage on the selective catalytic reduction carrier under the fixed working condition of the hybrid engine, and obtain the measurement value of the upstream nitrogen oxide sensor after a preset time interval;

[0159] A first acquisition module is used for performing injection according to different preset ammonia nitrogen ratios to obtain a downstream nitrogen oxygen sensor measurement value at the end time of each injection stage;

[0160] The calculation module is used to calculate the upstream nitrogen oxide sensor measurement value and the downstream nitrogen oxide sensor measurement value at the end of each injection stage to obtain the selective catalytic reduction conversion efficiency of the hybrid engine under fixed working conditions with different preset ammonia nitrogen ratios.

[0161] Furthermore, the comparison unit 503 includes:

[0162] A search module is used to search for a post-treatment crystallization efficiency curve according to different preset ammonia nitrogen ratios to obtain reference efficiencies of each post-treatment crystallization corresponding to different preset ammonia nitrogen ratios, and to search for a post-treatment aging efficiency curve according to each preset ammonia nitrogen ratio to obtain reference efficiencies of each post-treatment aging corresponding to different preset ammonia nitrogen ratios;

[0163] A first acquisition calculation module is used to obtain a first correlation coefficient according to the reference efficiency of each post-treatment crystallization corresponding to different preset ammonia nitrogen ratios and the selective catalytic reduction conversion efficiency of different preset ammonia nitrogen ratios, and calculate a first absolute value of the difference between the first correlation coefficient and the preset value;

[0164] A second acquisition calculation module is used to obtain a second correlation coefficient according to the reference efficiencies of various post-treatment aging corresponding to different preset ammonia nitrogen ratios and the selective catalytic reduction conversion efficiencies of different preset ammonia nitrogen ratios, and calculate a second absolute value of the difference between the second correlation coefficient and the preset value;

[0165] A judging module, used for judging whether the first absolute value is less than or equal to the second absolute value;

[0166] A second acquisition module, configured to obtain a first comparison result if the first absolute value is less than or equal to the second absolute value;

[0167] The third acquisition module is used to obtain a second comparison result if the first absolute value is greater than the second absolute value.

[0168] Further, the determining unit 504 includes:

[0169] A second determination module is used to determine that the fault type of the hybrid engine emission fault is an emission fault type of excessive exhaust emissions caused by post-treatment crystallization if the comparison result is the first comparison result;

[0170] The third determination module is used to determine that the fault type of the hybrid engine emission fault is the emission fault type of excessive exhaust emissions caused by after-treatment aging if the comparison result is the second comparison result.

[0171] Furthermore, the processing unit 505 includes:

[0172] A repair module, for triggering regeneration and clearing crystals to repair the emission fault if the fault type of the hybrid engine emission fault is an emission fault type of excessive exhaust emissions caused by post-treatment crystals;

[0173] The generating module is used to generate a prompt message if the fault type of the hybrid engine emission fault is the exhaust gas emission exceeding the standard caused by the aging of the post-treatment.

[0174] In the embodiment of the present application, in the process of fault diagnosis of the cause of excessive NOx emissions in the vehicle emission system, there is no need for the performance development engineer to analyze the operating data or to find the cause of the fault on site by traveling to solve the problem. It is only necessary to actively trigger the high emission fault cause diagnosis function after detecting that the exhaust emissions are high and last for a certain period of time, that is, the measurement value of the downstream nitrogen oxide sensor meets the fault detection condition, and adjust the engine to a fixed operating condition by utilizing the battery charging and discharging of the hybrid engine, collect the selective catalytic reduction conversion efficiency under different ammonia nitrogen ratio injection states under the fixed operating condition, and compare the correlation with the efficiency characteristic curves of the post-treatment crystallization state and the post-treatment aging state, so as to automatically diagnose the specific cause and fault type of excessive nitrogen oxide emissions in the vehicle emission system, and after identifying the specific cause and fault type, repair the vehicle fault or generate a prompt message to prompt the driver to go to the service station for inspection as soon as possible, so as to ensure that the nitrogen oxide emissions in the vehicle emission system do not exceed the limit value, reduce the fault risk of excessive nitrogen oxide emissions in the vehicle emission system, and improve the efficiency of fault diagnosis of the cause of excessive nitrogen oxide emissions in the vehicle emission system.

[0175] For the aforementioned method embodiments, for the sake of simplicity, they are all described as a series of action combinations, but those skilled in the art should be aware that the present application is not limited by the order of the actions described, because according to the present application, some steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also be aware that the embodiments described in the specification are all preferred embodiments, and the actions and modules involved are not necessarily required by the present application.

[0176] It should be noted that each embodiment in this specification is described in a progressive manner, and each embodiment focuses on the differences from other embodiments, and the same or similar parts between the embodiments can be referred to each other. For the device embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0177] The steps in the methods of the embodiments of the present application can be adjusted in order, combined, and deleted according to actual needs.

[0178] Finally, it should be noted that, in this article, relational terms such as first and second, etc. are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations.

[0179] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

[0180] The above is only a preferred implementation of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. A method for diagnosing emission faults of a hybrid engine, characterized in that: The method comprises: Real-time acquisition of measurements from the downstream NOx sensor of a hybrid engine; If the measurement value of the downstream nitrogen oxide sensor meets the fault detection condition, collecting the selective catalytic reduction conversion efficiency of the hybrid engine at different preset ammonia nitrogen ratios under fixed working conditions; The selective catalytic reduction conversion efficiency of different preset ammonia nitrogen ratios is compared with the pre-collected post-treatment crystallization efficiency curve and the pre-collected post-treatment aging efficiency curve to obtain a comparison result; Determining the fault type of the hybrid engine emission fault according to the comparison result; wherein the fault type at least includes the emission fault type of excessive exhaust gas emissions caused by post-treatment crystallization or the emission fault type of excessive exhaust gas emissions caused by post-treatment aging; Process the fault types of hybrid engine emission faults.

2. The method according to claim 1, characterized in that If the measured value of the downstream nitrogen oxide sensor meets the fault detection condition, collecting the selective catalytic reduction conversion efficiency of the hybrid engine under different preset ammonia nitrogen ratios under fixed working conditions, including: If the measurement value of the downstream nitrogen oxygen sensor is greater than a preset threshold, and the time during which the measurement value of the downstream nitrogen oxygen sensor is greater than the preset threshold is greater than a preset time, it is determined that the measurement value of the downstream nitrogen oxygen sensor meets the fault detection condition; When the measurement value of the downstream nitrogen oxide sensor meets the fault detection condition, adjusting the operating condition of the hybrid engine to a fixed operating condition in a preset manner; Under fixed operating conditions of the hybrid engine, the urea pump is controlled to clean the ammonia storage on the selective catalytic reduction carrier, and the upstream nitrogen oxide sensor measurement value is obtained after a preset time interval; Injection is performed according to different preset ammonia nitrogen ratios to obtain downstream nitrogen oxide sensor measurement values ​​at the end of each injection stage; The upstream nitrogen oxide sensor measurement value is calculated with the downstream nitrogen oxide sensor measurement value at the end of each injection phase to obtain the selective catalytic reduction conversion efficiency of the hybrid engine at different preset ammonia nitrogen ratios under fixed working conditions.

3. The method according to claim 1, characterized in that The selective catalytic reduction conversion efficiency of different preset ammonia nitrogen ratios is compared with the pre-collected post-treatment crystallization efficiency curve and the pre-collected post-treatment aging efficiency curve to obtain a comparison result, including: Searching for post-treatment crystallization efficiency curves according to different preset ammonia nitrogen ratios to obtain reference efficiencies of various post-treatment crystallizations corresponding to different preset ammonia nitrogen ratios, and searching for post-treatment aging efficiency curves according to various preset ammonia nitrogen ratios to obtain reference efficiencies of various post-treatment agings corresponding to different preset ammonia nitrogen ratios; Obtaining a first correlation coefficient according to the reference efficiencies of the post-treatment crystals corresponding to the different preset ammonia-nitrogen ratios and the selective catalytic reduction conversion efficiencies of the different preset ammonia-nitrogen ratios, and calculating a first absolute value of the difference between the first correlation coefficient and the preset value; According to the reference efficiencies of the post-treatment aging corresponding to the different preset ammonia-nitrogen ratios and the selective catalytic reduction conversion efficiencies of the different preset ammonia-nitrogen ratios, a second correlation coefficient is obtained, and a second absolute value of the difference between the second correlation coefficient and the preset value is calculated; Determine whether the first absolute value is less than or equal to the second absolute value; If the first absolute value is less than or equal to the second absolute value, a first comparison result is obtained; If the first absolute value is greater than the second absolute value, a second comparison result is obtained.

4. The method according to claim 3, characterized in that Determining the fault type of the hybrid engine emission fault according to the comparison result includes: If the comparison result is the first comparison result, it is determined that the fault type of the hybrid engine emission fault is an emission fault type of excessive exhaust emissions caused by post-treatment crystallization; If the comparison result is the second comparison result, it is determined that the fault type of the hybrid engine emission fault is an emission fault type of excessive exhaust emissions caused by after-treatment aging.

5. The method according to claim 1, characterized in that The processing of the fault type of the hybrid engine emission fault includes: If the fault type of the hybrid engine emission fault is an emission fault type of excessive exhaust emissions caused by post-processing crystallization, regeneration is triggered to clear the crystallization to repair the emission fault; If the fault type of the hybrid engine emission fault is an emission fault type of excessive exhaust emissions caused by after-treatment aging, a prompt message is generated.

6. A hybrid engine emission fault diagnosis device, characterized in that: The device comprises: A first acquisition unit, used for acquiring the measurement value of a downstream nitrogen oxygen sensor of the hybrid engine in real time; A second collection unit is used to collect the selective catalytic reduction conversion efficiency of the hybrid engine at different preset ammonia nitrogen ratios under fixed working conditions if the measurement value of the downstream nitrogen oxide sensor meets the fault detection condition; A comparison unit is used to compare the selective catalytic reduction conversion efficiency of different preset ammonia nitrogen ratios with the pre-collected post-treatment crystallization efficiency curve and the pre-collected post-treatment aging efficiency curve to obtain a comparison result; A determination unit, configured to determine the fault type of the hybrid engine emission fault according to the comparison result; wherein the fault type at least includes the emission fault type of excessive exhaust gas emissions caused by post-treatment crystallization or the emission fault type of excessive exhaust gas emissions caused by post-treatment aging; The processing unit is used for processing the fault type of hybrid engine emission fault.

7. The device according to claim 6, characterized in that The second acquisition unit includes: A first determination module, configured to determine that the measurement value of the downstream nitrogen oxygen sensor meets a fault detection condition if the measurement value of the downstream nitrogen oxygen sensor is greater than a preset threshold and the time during which the measurement value of the downstream nitrogen oxygen sensor is greater than the preset threshold is greater than a preset time; An adjustment module, configured to adjust the operating condition of the hybrid engine to a fixed operating condition in a preset manner when the measurement value of the downstream nitrogen oxide sensor meets the fault detection condition; A control acquisition module is used to control the urea pump to clean the ammonia storage on the selective catalytic reduction carrier under the fixed working condition of the hybrid engine, and obtain the measurement value of the upstream nitrogen oxide sensor after a preset time interval; A first acquisition module is used for performing injection according to different preset ammonia nitrogen ratios to obtain a downstream nitrogen oxygen sensor measurement value at the end time of each injection stage; The calculation module is used to calculate the upstream nitrogen oxide sensor measurement value and the downstream nitrogen oxide sensor measurement value at the end time of each injection stage respectively, so as to obtain the selective catalytic reduction conversion efficiency of the hybrid engine under fixed working conditions with different preset ammonia nitrogen ratios.

8. The device according to claim 6, characterized in that The comparison unit comprises: A search module is used to search for a post-treatment crystallization efficiency curve according to different preset ammonia nitrogen ratios to obtain reference efficiencies of each post-treatment crystallization corresponding to different preset ammonia nitrogen ratios, and to search for a post-treatment aging efficiency curve according to each preset ammonia nitrogen ratio to obtain reference efficiencies of each post-treatment aging corresponding to different preset ammonia nitrogen ratios; A first acquisition calculation module is used to obtain a first correlation coefficient according to the reference efficiency of each post-treatment crystallization corresponding to the different preset ammonia-nitrogen ratios and the selective catalytic reduction conversion efficiency of the different preset ammonia-nitrogen ratios, and calculate a first absolute value of the difference between the first correlation coefficient and the preset value; A second acquisition calculation module is used to obtain a second correlation coefficient according to the reference efficiency of each post-treatment aging corresponding to the different preset ammonia nitrogen ratios and the selective catalytic reduction conversion efficiency of the different preset ammonia nitrogen ratios, and calculate a second absolute value of the difference between the second correlation coefficient and the preset value; A judging module, used for judging whether the first absolute value is less than or equal to the second absolute value; A second acquisition module, configured to obtain a first comparison result if the first absolute value is less than or equal to the second absolute value; The third acquisition module is used to obtain a second comparison result if the first absolute value is greater than the second absolute value.

9. The device according to claim 8, characterized in that The determining unit comprises: a second determination module, configured to determine, if the comparison result is the first comparison result, that the fault type of the hybrid engine emission fault is an emission fault type of excessive exhaust emissions caused by post-treatment crystallization; The third determination module is used to determine that the fault type of the hybrid engine emission fault is an emission fault type of excessive exhaust emissions caused by after-treatment aging if the comparison result is the second comparison result.

10. The device according to claim 6, characterized in that The processing unit comprises: A repair module, for triggering regeneration and clearing crystals to repair the emission fault if the fault type of the hybrid engine emission fault is an emission fault type of excessive exhaust emissions caused by post-treatment crystals; The generating module is used to generate a prompt message if the fault type of the hybrid engine emission fault is the exhaust gas emission exceeding the standard caused by the aging of the post-processing.

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