DOC efficiency fault diagnosis method, device, electronic device, storage medium and diesel vehicle

Abstract

The present invention discloses a DOC efficiency fault diagnosis method, device, electronic device, storage medium and diesel vehicle. The diagnosis method comprises: judging whether the DOC efficiency first-level diagnosis enable and the second-level diagnosis enable are established. When the DOC efficiency first-level diagnosis enable and the DOC efficiency second-level diagnosis enable are established, the timing is started and the time is accumulated. The time accumulation value is A. 1 ; When the DOC efficiency level 1 diagnosis is enabled and the DOC efficiency level 2 diagnosis is not enabled, the time accumulation value is A 1 Maintain the current value unchanged; when the DOC efficiency level 1 diagnosis is not enabled, the time accumulation value is A 1 Clear directly; compare the time accumulated value A 1 With calibration limit A 2 : When A 1＞ A 2 When the current DOC efficiency value η is compared with the DOC efficiency calibration limit η min , if η<η min , then the DOC low efficiency fault is established, if η ≥ η min , then the DOC efficiency is normal; when A 1≤ A 2 When , the process returns to step 1. The present invention can accurately monitor DOC efficiency failures and prevent false alarms and missed alarms.

Description

Technical Field

[0001] The present invention relates to the technical field of control of diesel engine exhaust purification treatment, and in particular to a DOC efficiency fault diagnosis method, device, electronic equipment, storage medium and diesel vehicle. Background Art

[0002] The patent with publication number CN103362621A discloses a non-methane hydrocarbon conversion efficiency diagnosis of a diesel aftertreatment system. The patent introduces a DOC efficiency diagnosis method: the DOC efficiency is judged according to the difference between the DOC outlet temperature and the DOC inlet temperature. When the temperature difference between the DOC outlet and the inlet is less than the calibration limit, the DOC is considered to be ineffective. In addition, in other existing technologies, the DOC efficiency is mostly diagnosed by comparing the theoretical temperature difference between the DOC outlet and the inlet with the measured temperature difference.

[0003] The prior art still has the following defects:

[0004] 1) The existing technology focuses on the calculation method of DOC efficiency, ignoring the importance of diagnostic window selection. If the diagnostic window is not selected properly, it is easy to cause false alarms of low DOC efficiency faults, thereby causing problems such as vehicle speed and torque limits, greatly affecting the driving experience;

[0005] 2) In the prior art, the theoretical outlet temperature of DOC is calculated by the calorific value and combustion efficiency of the fuel, without considering the specific degree of chemical reaction inside the DOC, and the accuracy is not high, thus affecting the calculation accuracy of the DOC efficiency;

[0006] 3) In the prior art, the temperatures at two different locations, the DOC outlet and the inlet, are used for comparison. However, there is a time delay between the DOC outlet temperature and the inlet temperature, which affects the accuracy of the DOC efficiency. Summary of the invention

[0007] DOC increases the temperature of DPF by oxidizing HC, and its efficiency directly affects the treatment effect of carbon soot in exhaust gas, so it is necessary to accurately monitor the DOC efficiency to prevent false alarms and missed alarms. Based on this, the present invention provides a DOC efficiency fault diagnosis method to improve the accuracy of DOC efficiency diagnosis and reduce the false alarm rate of DOC efficiency faults.

[0008] In order to solve the above technical problems, the present invention is implemented by the following technical solutions:

[0009] Step 1: Determine whether the DOC efficiency level 1 diagnosis and DOC efficiency level 2 diagnosis are enabled:

[0010] When the engine state is in the DPF regeneration mode, the measured temperature T1 at the DOC outlet and the accumulated HC value S1 at the DOC inlet are obtained;

[0011] Based on the measured temperature T1 at the DOC outlet and the accumulated HC value S1 at the DOC inlet, determining whether the DOC efficiency primary diagnosis is enabled;

[0012] When the exhaust flow rate Q1 is greater than the calibrated limit value Q2, the measured DOC outlet temperature T1, the actual regeneration HC injection amount L1 and the main injection HC amount L3 are obtained;

[0013] Based on the measured DOC outlet temperature T1, the actual regeneration HC injection amount L1 and the main injection HC amount L3, it is determined whether the DOC efficiency secondary diagnosis is enabled:

[0014] Step 2: Based on the judgment result of step 1, diagnose whether there is a fault in DOC efficiency:

[0015] When both the DOC efficiency level 1 diagnosis enable and the DOC efficiency level 2 diagnosis enable are established, the timing starts and the time is accumulated, and the accumulated time value is A1; when the DOC efficiency level 1 diagnosis enable is established and the DOC efficiency level 2 diagnosis enable is not established, the accumulated time value is A1 and the current value remains unchanged; when the DOC efficiency level 1 diagnosis enable is not established, the accumulated time value is A1 and is directly cleared to zero;

[0016] Compare the time accumulated value A1 with the calibration limit value A2: When A 1＞ At A2, compare the current DOC efficiency value η with the DOC efficiency calibration limit η min , if η<η min , then the DOC low efficiency fault is established, if η ≥ η min , then the DOC efficiency is normal; when A 1≤ When A2, return to step 1.

[0017] Preferably, judging whether the DOC efficiency primary diagnosis is enabled based on the measured DOC outlet temperature T1 and the HC accumulated value S1 at the DOC inlet comprises the following steps:

[0018] When the drop of the measured temperature T1 at the DOC outlet is less than the calibration value ε1 and the HC value S1 at the DOC inlet is greater than the calibration limit S2, the first-level diagnosis of DOC efficiency is enabled, otherwise it is not enabled.

[0019] Preferably, judging whether the DOC efficiency secondary diagnosis is enabled based on the measured DOC outlet temperature T1, the actual regeneration HC injection amount L1 and the main injection HC amount L3 comprises the following steps:

[0020] When the measured temperature T1 at the DOC outlet is within the design range and the change gradient is less than the calibration value ε2, the relative deviation between the actual regeneration HC injection amount L1 and the target regeneration HC injection amount L2 does not exceed 3%, and the main injection HC amount L3 is greater than the calibration value L4, the DOC efficiency secondary diagnosis is enabled, otherwise it is not enabled.

[0021] Preferably, the calculation formula of the DOC efficiency value η is as follows:

[0022]

[0023] Wherein, T1: measured temperature at DOC outlet; T0: T0 = T3-ΔT, T3 is measured temperature at DOC inlet, ΔT is internal temperature loss of DOC in non-regeneration state; T2: DOC outlet temperature calculated according to CSTR model.

[0024] Further preferably, the method for obtaining the internal temperature loss ΔT of the DOC in a non-regeneration state is as follows: when the DOC is in a non-regeneration state, the heat release from oxidation inside the DOC is not considered, and only the temperature loss during the heat conduction process inside the DOC is considered. At this time, the temperature loss inside the DOC is mainly related to the exhaust flow rate; temperature sensors are arranged at the inlet and outlet of the DOC, and the temperature loss inside the DOC is measured at different exhaust flow rates, and then filled in the corresponding positions of the Table to obtain the calibration database Table; the corresponding ΔT can be obtained by searching the database Table through the exhaust flow rate Q1.

[0025] Further preferably, the method for obtaining the DOC outlet temperature T2 is as follows: the DOC is sliced, and each slice uses the CSTR method to simulate the oxidation reaction inside the DOC to obtain the concentration of each reactant, and the temperature change of each slice is obtained based on the reaction exotherm combined with the heat loss inside the DOC. After the calculation of the current slice is completed, the concentration of each reactant and the exhaust temperature are output to the next slice, and the exhaust temperature calculated for the last slice is T2.

[0026] A DOC efficiency diagnostic device, comprising:

[0027] An acquisition module, used for acquiring information to be diagnosed of a plurality of modules to be diagnosed, wherein the information to be diagnosed includes a DOC outlet measured temperature T1, a HC accumulated value S1 at a DOC inlet, a DOC outlet measured temperature T1, an actual regeneration HC injection amount L1, and a main injection HC amount L3;

[0028] A judgment module, used to compare each to-be-diagnosed information with the preset diagnosis information, and judge whether the DOC efficiency primary diagnosis enabling and the DOC efficiency secondary diagnosis enabling are established;

[0029] An analysis module, used to analyze the diagnostic information according to the script corresponding to the diagnostic information obtained by the judgment module, and obtain the diagnostic content in the diagnostic information;

[0030] A generating module is used to generate a diagnosis result according to the diagnosis content acquired by the analyzing module.

[0031] An electronic device comprises a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the processor implements the method described in the above scheme when executing the computer program.

[0032] A computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the method described in the above scheme is implemented.

[0033] A diesel vehicle comprises the device as described in the above scheme.

[0034] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0035] 1. The present invention reduces the internal thermal resistance of the DOC by limiting the engine state, ensures that the DOC is in a high-efficiency range by limiting the DOC state, and ensures that the regeneration oil injection is normal by limiting the HC injection amount, so that the DOC efficiency diagnosis is performed when the DOC works in the optimal range, thereby achieving the purpose of optimizing the DOC efficiency diagnosis window and reducing the false alarm rate.

[0036] 2. The present invention adopts the CSTR model to calculate the DOC theoretical outlet temperature, thereby improving the calculation accuracy of the DOC outlet temperature. The DOC efficiency calculation is related to the DOC outlet temperature, thereby improving the accuracy of the DOC efficiency calculation.

[0037] 3. In the prior art, the temperatures at two different locations, the DOC outlet and the inlet, are used for comparison. However, there is a time delay between the DOC outlet temperature and the inlet temperature. Now, the temperature comparison benchmark is set at the DOC outlet, thereby improving the accuracy of the DOC efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is a DOC efficiency diagnosis flow chart of the present invention;

[0039] Figure 2 It is the cumulative diagram of the diagnostic window time;

[0040] Figure 3 Produce a diagram for DOC low efficiency fault report. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] The embodiments of the present invention are further described in detail below with reference to the accompanying drawings.

[0043] The embodiments of the present invention provide a DOC efficiency fault diagnosis method, device, electronic device, storage medium and diesel vehicle to improve the accuracy of DOC efficiency diagnosis of a target vehicle.

[0044] In order to achieve the above technical effects, the overall idea of ​​the present invention is as follows:

[0045] A DOC efficiency fault diagnosis method comprises the following steps:

[0046] Step 1: Determine whether the DOC efficiency level 1 diagnosis and DOC efficiency level 2 diagnosis are enabled:

[0047] When the engine state is in the DPF regeneration mode, the measured temperature T1 at the DOC outlet and the accumulated HC value S1 at the DOC inlet are obtained;

[0048] Based on the measured temperature T1 at the DOC outlet and the accumulated HC value S1 at the DOC inlet, determining whether the DOC efficiency primary diagnosis is enabled;

[0049] When the exhaust flow rate Q1 is greater than the calibrated limit value Q2, the measured DOC outlet temperature T1, the actual regeneration HC injection amount L1 and the main injection HC amount L3 are obtained;

[0050] Based on the measured DOC outlet temperature T1, the actual regeneration HC injection amount L1 and the main injection HC amount L3, it is determined whether the DOC efficiency secondary diagnosis is enabled:

[0051] Step 2: Based on the judgment result of step 1, diagnose whether there is a fault in DOC efficiency:

[0052] When both the DOC efficiency level 1 diagnosis enable and the DOC efficiency level 2 diagnosis enable are established, the timing starts and the time is accumulated, and the accumulated time value is A1; when the DOC efficiency level 1 diagnosis enable is established and the DOC efficiency level 2 diagnosis enable is not established, the accumulated time value is A1 and the current value remains unchanged; when the DOC efficiency level 1 diagnosis enable is not established, the accumulated time value is A1 and is directly cleared to zero;

[0053] Compare the time accumulated value A1 with the calibration limit A2: When the time accumulated value A1 is greater than the calibration limit A2, compare the current DOC efficiency value η with the DOC efficiency calibration limit η min , if η<η min , then the DOC low efficiency fault is established, if η ≥ η min , the DOC efficiency is normal; when the time accumulated value A1 is less than or equal to the calibration limit A2, return to step 1.

[0054] The embodiments of the present invention are further described in detail below with reference to the accompanying drawings.

[0055] See also Figure 1-3 As shown, an embodiment of the present invention provides a DOC efficiency fault diagnosis method, the method comprising the following steps:

[0056] S1, when the engine state is in the DPF regeneration mode, obtain the measured temperature T1 at the DOC outlet and the accumulated HC value S1 at the DOC inlet;

[0057] The oxidation catalytic converter, referred to as DOC (Diesel Oxidation Catalyst), is installed in the engine exhaust pipe. Through oxidation reaction, it converts carbon monoxide (CO) and hydrocarbons (HC) in the engine exhaust into harmless water (H20) and carbon dioxide (CO2), and oxidizes nitrogen monoxide NO in the exhaust gas into nitrogen dioxide NO2. T1 is measured by the temperature sensor.

[0058] DPF (Diesel Particulate Filter) is the abbreviation of diesel particulate filter. The diesel particulate filter is installed in the exhaust system of diesel vehicles and is a device used to filter and reduce soot particles in the exhaust. The method of filtering soot particles is to capture the soot particles in the exhaust system of diesel vehicles through diffusion precipitation, inertial precipitation and linear interception. The DPF particle filter can effectively purify 65-90% of the soot particles in the exhaust gas. It is one of the most effective and direct methods to purify the particulate matter generated by diesel vehicles.

[0059] S2, based on the measured temperature T1 at the DOC outlet and the accumulated HC value S1 at the DOC inlet, judging whether the DOC efficiency first-level diagnosis is enabled;

[0060] Specifically, when the drop of the measured temperature T1 at the DOC outlet is less than the calibration value ε1 and the HC value S1 at the DOC inlet is greater than the calibration limit S2, the first-level diagnosis of DOC efficiency is enabled, otherwise it is not enabled.

[0061] Things to note are as follows:

[0062] i) DOC mainly increases the temperature of DPF by oxidizing HC, and HC injection for DPF temperature increase is mainly performed during the DPF regeneration stage, so DOC efficiency diagnosis is meaningful only during the DPF regeneration stage;

[0063] ii) When post-injection occurs in the cylinder or the 7th nozzle is cut off during the DPF regeneration phase (such as when the exhaust brake is turned on), the DOC outlet temperature T1 will drop significantly; when the restriction is lifted and the fuel is re-injected, the DOC ignition takes time and there is a delay in the actual temperature transmission, which will cause a delay in the change of T1. However, the DOC outlet model temperature T2 is calculated in real time. According to the DOC efficiency calculation formula 1, the DOC efficiency calculation at this time will be biased. Therefore, the DPF inlet measured temperature T1 in the regeneration phase is not suitable as a DOC efficiency fault diagnosis condition during the period of ramping up again;

[0064] iii) When the HC accumulation at the DOC inlet is sufficient, the DOC has fully reacted and it is appropriate to perform DOC efficiency diagnosis.

[0065] S3, when the exhaust flow rate Q1 is greater than the calibration limit value Q2, the actual measured temperature T1 at the DOC outlet, the actual regeneration HC injection amount L1 and the main injection HC amount L3 are obtained;

[0066] S4. Based on the measured DOC outlet temperature T1, the actual regeneration HC injection amount L1 and the main injection HC amount L3, determine whether the DOC efficiency secondary diagnosis is enabled:

[0067] Specifically, when the measured temperature T1 at the DOC outlet is within the design range and the change gradient is less than the calibration value ε2, the relative deviation between the actual regeneration HC injection amount L1 and the target regeneration HC injection amount L2 does not exceed 3%, and the main injection HC amount L3 is greater than the calibration value L4, the DOC efficiency secondary diagnosis is enabled, otherwise it is not enabled.

[0068] Things to note are as follows:

[0069] i) The exhaust flow rate is greater than the limit value in order to reduce the internal thermal resistance of the DOC;

[0070] ii) The limitation of the measured temperature T1 at the DOC outlet is to ensure that the DOC is in the efficient and safe range;

[0071] iii) In the existing market strategy, there are restrictive measures such as smoke limit, maximum oil limit, exhaust brake and calibration quantity assignment between the target regeneration HC injection amount L2 and the actual regeneration HC injection amount L1, which may cause differences between L2 and L1; and the DOC outlet model temperature T2 is obtained according to the target regeneration HC injection amount L2 (after the regeneration HC is injected into the DOC, it is first cracked into C3H6, and then T2 is obtained through the CSTR model), and the DOC outlet measured temperature T1 is related to the actual regeneration HC injection amount L1. According to the DOC efficiency calculation formula 1, the efficiency calculation of DOC at this time will deviate, so the deviation between L1 and L2 needs to be limited.

[0072] iiii) During the regeneration process, when the main fuel injection amount of the engine is very small or even reverse, the original exhaust temperature of the engine is very low, which directly affects the rate of the chemical reaction in the DOC, so the main fuel injection amount is limited.

[0073] S5. When both the DOC efficiency primary diagnosis enable and the DOC efficiency secondary diagnosis enable are established, the timing starts and the time is accumulated, and the accumulated time value is A1; when the DOC efficiency primary diagnosis enable is established and the DOC efficiency secondary diagnosis enable is not established, the accumulated time value is A1 and the current value remains unchanged; when the DOC efficiency primary diagnosis enable is not established, the accumulated time value is A1 and is directly cleared to zero;

[0074] Compare the time accumulated value A1 with the calibration limit A2: When the time accumulated value A1 is greater than the calibration limit A2, compare the current DOC efficiency value η with the DOC efficiency calibration limit η min , if η<η min , then the DOC low efficiency fault is established, if η ≥ η min , the DOC efficiency is normal; when the time accumulated value A1 is less than or equal to the calibration limit A2, return to step S1.

[0075] Specifically, the calculation formula of DOC efficiency value η is as follows:

[0076]

[0077] Wherein, T1: measured temperature at DOC outlet;

[0078] T0: T0 = T3-ΔT, T3 is the measured temperature at the DOC inlet, ΔT is the internal temperature loss of the DOC in a non-regeneration state; the heat release of oxidation inside the DOC is not considered, only the temperature loss during the heat conduction process inside the DOC is considered, and the DOC outlet temperature T0 is obtained by combining the DOC inlet temperature T3 with the DOC internal temperature loss ΔT; Q1 is measured by a flow sensor, and T3 is measured by a temperature sensor;

[0079] T2: DOC outlet temperature calculated according to the CSTR model.

[0080] The CSTR model (continuous stirred tank reactor) has the following characteristics:

[0081] 1. The concentration and temperature of the material in the reactor are uniform and the same as the temperature and concentration of the outlet material;

[0082] 2. Fresh materials are mixed evenly instantly.

[0083] The method for obtaining the DOC outlet temperature T2 is as follows: slice the DOC according to its actual size (generally, each 10 cm DOC cylinder can be calculated as a slice), and each slice uses the CSTR method to simulate the oxidation reaction inside the DOC, and the concentration of each reactant (NO, NO2, CO, O2, C3H6) is obtained by formula 2-4; the reaction heat of each oxidation reaction is fixed, and the reaction heat of each oxidation reaction combined with the change in the concentration of each reactant can obtain the total reaction heat q of the slice (Formula 5); the outlet temperature T of each slice is obtained according to the energy conservation NS equation i After the current slice calculation is completed, the concentration of each reactant and the outlet temperature T are output. i For the next slice, the outlet temperature T calculated from the last slice is i That is T2.

[0084] There are three main chemical reactions inside DOC:

[0085]

[0086]

[0087]

[0088] The differential form of the chemical reaction rate for each slice is as follows:

[0089]

[0090]

[0091]

[0092] Where: r NO : NO oxidation reaction rate, r C3H6 : C3H6 oxidation reaction rate, r CO : CO oxidation reaction rate; K3: Arrhenius constant for NO oxidation reaction, K2: Arrhenius constant for C3H6 oxidation reaction, K1: Arrhenius constant for CO oxidation reaction; x NO : initial NO concentration; x CO: initial CO concentration; x C3H6 : Initial concentration of C3H6; x O2 :O2 initial concentration; x NO2 : initial concentration of NO2; K p is the chemical equilibrium constant, and n is the correction factor.

[0093] The total reaction heat release q for each slice is as follows:

[0094] q=(q1*r CO +q2*r C3H6 +q3*r NO )dt (5)

[0095] Where: q: total heat release of each slice; q1: heat of CO oxidation reaction, q2: heat of C3H6 oxidation reaction, q3: heat of NO oxidation reaction. According to the energy conservation NS equation, the outlet temperature T of each slice can be obtained. i , the outlet temperature T calculated for the last slice i This is T2. The NS equation is a standard equation and will not be explained in detail here.

[0096] Based on the same inventive concept as the DOC efficiency fault diagnosis method embodiment, the embodiment of the present invention provides a DOC efficiency diagnosis device, which includes:

[0097] An acquisition module, used for acquiring information to be diagnosed of multiple modules to be diagnosed, the information to be diagnosed including the actual temperature T1 at the DOC outlet, the HC value S1 at the DOC inlet, the actual temperature T1 at the DOC outlet, the actual regeneration HC injection amount L1 and the main injection HC amount L3;

[0098] A judgment module, used to compare each to-be-diagnosed information with the preset diagnosis information, and judge whether the DOC efficiency primary diagnosis enabling and the DOC efficiency secondary diagnosis enabling are established;

[0099] An analysis module is used to analyze the diagnostic information according to the script corresponding to the diagnostic information obtained by the judgment module, and obtain the diagnostic content in the diagnostic information;

[0100] The generation module is used to generate a diagnosis result based on the diagnosis content obtained by the analysis module.

[0101] Based on the same inventive concept as the DOC efficiency fault diagnosis method embodiment, an embodiment of the present invention provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the method described in the above scheme when executing the computer program.

[0102] Based on the same inventive concept as the embodiments of the DOC efficiency fault diagnosis method, an embodiment of the present invention provides a computer-readable storage medium storing a computer program, and when the computer program is executed by a processor, the method described in the above solution is implemented.

[0103] Based on the same inventive concept as the embodiments of the DOC efficiency diagnosis device, an embodiment of the present invention provides a diesel vehicle including the device described in the above solution.

[0104] The effectiveness of the diagnosis method of the present invention is verified below. Among them, the research object is a DOC with a known low efficiency fault, and the verification method is as follows:

[0105] Step 1: When the engine state is in the DPF regeneration mode, obtain that the measured temperature T1 at the DOC outlet is 580 °C (590 °C at the previous moment), the measured temperature T3 at the DOC inlet is 572.6 °C, and the HC accumulation value S1 at the DOC inlet is 38 g;

[0106] Step 2: When the decrease rate of the measured temperature T1 at the DOC outlet is 1.7%, less than the calibrated value ε1 (ε1 = 10%), and the HC value S1 (38 g) at the DOC inlet is greater than the calibrated limit S2 (35 g), the DOC efficiency primary diagnosis enablement is established;

[0107] Step 3: When the exhaust gas flow Q1 (300 g / s) is greater than the calibrated limit Q2 (95 g / s), obtain that the measured temperature T1 at the DOC outlet is 580 °C, the actual regeneration HC injection amount L1 is 9.4 mg / str, the target regeneration HC injection amount L2 is 9.3 mg / str, and the main injection HC amount L3 is 86 mg / str;

[0108] Step 4: When the measured temperature T1 at the DOC outlet is 580 °C, within the design range (500 °C < T1 < 600 °C), the change gradient of T1 is 1.7%, less than the calibrated value of 5%, the relative deviation between the actual regeneration HC injection amount L1 and the target regeneration HC injection amount L2 is 1.06%, not exceeding 3%, and the main injection HC amount L3 (86 mg / str) is greater than the calibrated value L4 (8 mg / str), the DOC efficiency secondary diagnosis enablement is established;

[0109] Step 5: When both the DOC efficiency primary diagnosis enablement and the DOC efficiency secondary diagnosis enablement are established, start timing and accumulate the time to obtain a time accumulation value of A1 (232 s). The time accumulation value A1 (232 s) is greater than the calibrated limit A2 (230 s), and compare the current DOC efficiency value η with the DOC efficiency calibrated limit η min (η min = 0.2), and the calculation process of the current DOC efficiency value η is as follows:

[0110]

[0111] Wherein, T1: measured temperature at DOC outlet; T0: T0 = T3-ΔT, T3 is measured temperature at DOC inlet, ΔT is internal temperature loss of DOC in non-regeneration state; T2: DOC outlet temperature calculated according to CSTR model.

[0112] After calculation, T2 is 630.8℃, T0 is 569.4℃, ΔT is 3.2℃, and the current DOC efficiency value η is 0.17, that is, η<η min , then the DOC efficiency is low fault; it can be seen that the diagnostic result obtained by the diagnostic method of the present invention is consistent with the actual result. Therefore, the use of the diagnostic method of the present invention can accurately diagnose whether the DOC efficiency is faulty, and can reduce the false alarm rate of DOC efficiency faults.

[0113] A person skilled in the art can understand that all or part of the processes in the above-mentioned embodiments can be implemented by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to a memory, a database or other medium used in the embodiments provided by the present invention can include at least one of a non-volatile and a volatile memory.

[0114] The above is only a specific embodiment of the present invention, so that those skilled in the art can understand or implement the present invention. 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 spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but should conform to the widest scope consistent with the principles and novel features invented herein.

Claims

1. A DOC efficiency fault diagnosis method, characterized in that: The following steps are involved: Step 1: Determine whether the DOC efficiency level 1 diagnosis and DOC efficiency level 2 diagnosis are enabled: When the engine state is in the DPF regeneration mode, the measured temperature T1 at the DOC outlet and the accumulated HC value S1 at the DOC inlet are obtained; Based on the measured temperature T1 at the DOC outlet and the accumulated HC value S1 at the DOC inlet, determining whether the DOC efficiency first-level diagnosis is enabled; When the exhaust flow rate Q1 is greater than the calibrated limit value Q2, the measured temperature T1 at the DOC outlet, the actual regeneration HC injection amount L1 and the main injection HC amount L3 are obtained; Based on the measured DOC outlet temperature T1, the actual regeneration HC injection amount L1 and the main injection HC amount L3, it is determined whether the DOC efficiency secondary diagnosis is enabled: Step 2: Based on the judgment result of step 1, diagnose whether there is a fault in DOC efficiency: When both the DOC efficiency level 1 diagnosis enable and the DOC efficiency level 2 diagnosis enable are established, the timing starts and the time is accumulated, and the accumulated time value is A1; when the DOC efficiency level 1 diagnosis enable is established and the DOC efficiency level 2 diagnosis enable is not established, the accumulated time value is A1 and the current value remains unchanged; When the DOC efficiency level 1 diagnosis is not enabled, the time accumulation value is directly cleared to zero for A1; Compare the time accumulated value A1 with the calibration limit A2: When A1>A2, compare the current DOC efficiency value η with the DOC efficiency calibration limit η min , if η<η min , then the DOC low efficiency fault is established, if η ≥ η min , then the DOC efficiency is normal; when A1≤A2, return to step 1; The method of judging whether the DOC efficiency level 1 diagnosis is enabled based on the measured DOC outlet temperature T1 and the HC accumulated value S1 at the DOC inlet comprises the following steps: When the drop of the measured temperature T1 at the DOC outlet is less than the calibration value ε1, and the HC value S1 at the DOC inlet is greater than the calibration limit S2, the first-level diagnosis of DOC efficiency is enabled, otherwise it is not enabled; The method of judging whether the DOC efficiency secondary diagnosis is enabled based on the DOC outlet measured temperature T1, the actual regeneration HC injection amount L1 and the main injection HC amount L3 comprises the following steps: When the measured temperature T1 at the DOC outlet is within the design range and the change gradient is less than the calibration value ε2, the relative deviation between the actual regeneration HC injection amount L1 and the target regeneration HC injection amount L2 does not exceed 3%, and the main injection HC amount L3 is greater than the calibration value L4, the DOC efficiency secondary diagnosis is enabled, otherwise it is not enabled.

2. The DOC efficiency fault diagnosis method according to claim 1, characterized in that: The calculation formula of the DOC efficiency value η is as follows: Wherein, T1: measured temperature at DOC outlet; T0: T0 = T3-ΔT, T3 is measured temperature at DOC inlet, ΔT is internal temperature loss of DOC in non-regeneration state; T2: DOC outlet temperature calculated according to CSTR model.

3. The DOC efficiency fault diagnosis method according to claim 2, characterized in that: The method for obtaining the internal temperature loss ΔT of the DOC in a non-regeneration state is as follows: when the DOC is in a non-regeneration state, the oxidation heat release inside the DOC is not considered, and only the temperature loss in the heat conduction process inside the DOC is considered. At this time, the temperature loss inside the DOC is mainly related to the exhaust flow rate; temperature sensors are arranged at the inlet and outlet of the DOC, and the temperature loss inside the DOC is measured at different exhaust flow rates, and then filled in the corresponding positions of the Table to obtain the calibration database Table; the corresponding ΔT can be obtained by searching the database Table through the exhaust flow rate Q1.

4. The DOC efficiency fault diagnosis method according to claim 2, characterized in that: The method for obtaining the DOC outlet temperature T2 is as follows: slice the DOC, and use the CSTR method to simulate the oxidation reaction inside the DOC to obtain the concentration of each reactant in each slice, and obtain the temperature change of each slice based on the reaction exotherm combined with the heat loss inside the DOC. After the calculation of the current slice is completed, the concentration of each reactant and the exhaust temperature are output to the next slice. The exhaust temperature calculated by the last slice is T2.

5. A DOC efficiency diagnostic device, characterized in that: The device is used to execute the method according to any one of claims 1 to 4, and the device comprises: An acquisition module, used for acquiring information to be diagnosed of multiple modules to be diagnosed, wherein the information to be diagnosed includes a DOC inlet measured temperature T0, a DOC inlet HC accumulated value S1, a DOC outlet measured temperature T1, an actual regeneration HC injection amount L1, and a main injection HC amount L3; A judgment module, used to compare each to-be-diagnosed information with the preset diagnosis information, and judge whether the DOC efficiency primary diagnosis enabling and the DOC efficiency secondary diagnosis enabling are established; An analysis module, used to analyze the diagnostic information according to the script corresponding to the diagnostic information obtained by the judgment module, and obtain the diagnostic content in the diagnostic information; A generating module is used to generate a diagnosis result according to the diagnosis content acquired by the analyzing module.

6. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the computer program, the method according to any one of claims 1 to 4 is implemented.

7. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the method according to any one of claims 1 to 4 is implemented.

8. A diesel vehicle, characterized in that: Comprising the device as claimed in claim 5.

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