Exhaust purification aftertreatment control method, controller and aftertreatment system

Abstract

The invention provides an exhaust purification aftertreatment control method, a controller and an aftertreatment system, and solves the technical problems that in the prior art, when an engine runs, sulfur, HC and the like poison a preceding-stage SCR, performance is reduced, and emission of NOx and N2O exceeds the standard. The invention provides an exhaust purification aftertreatment control method. In regeneration control, when the feed-forward oil quantity is calculated, the first temperature in front of a first nitrogen oxide treatment device is adopted as the input temperature, the temperature of the position where an outlet of a particle capturing device is located is adopted as the target temperature, and the oil injection quantity needed by feed-forward is calculated; meanwhile, the HC conversion efficiency of the first-stage nitrogen oxide treatment device and the HC conversion efficiency of the particle capturing device are used for correcting the feed-forward oil amount, the precision under transient oil injection control is improved, the actual temperature of the particle capturing device is made to be attached to the target temperature, and it is guaranteed that detoxification of the first-stage nitrogen oxide treatment device and sufficient oxidation of particles in the particle capturing device are achieved.

Description

Technical Field

[0001] This application relates to the technical field of automotive exhaust emissions, and specifically relates to an exhaust gas purification post-treatment control method, a controller, and a post-treatment system. Background Art

[0002] Automobile exhaust is the waste gas generated when an automobile is in use, containing hundreds of different compounds, and the pollutants therein include solid suspended particles, carbon monoxide, carbon dioxide, hydrocarbons, nitrogen oxides, lead, sulfur oxides, etc. Therefore, the exhaust gas generated by an automobile engine often needs to be treated during emission.

[0003] During the process of treating exhaust gas, an oxidation type catalytic converter (Diesel Oxidation Catalyst, DOC) is usually used to treat the exhaust gas, so as to convert nitrogen monoxide and hydrocarbons in the exhaust gas into water and carbon dioxide, and a selective catalytic reduction device (selectively catalytic reduction, SCR) is adopted to inject urea before the SCR to reduce nitrogen oxides in the exhaust gas emission. A diesel particulate filter (Diesel Particulate Filter, DPF) is used to filter particulate matter in the exhaust gas, thereby reducing particulate matter emissions in the exhaust gas.

[0004] However, during engine operation, sulfur, HC, etc. will poison the front-stage SCR, resulting in performance degradation and causing excessive emissions of NOx and N2O. Summary of the Invention

[0005] In view of this, this application provides an exhaust gas purification post-treatment control method, a controller, and a post-treatment system, which solve the technical problem that during engine operation, sulfur, HC, etc. will poison the front-stage SCR, resulting in performance degradation and causing excessive emissions of NOx and N2O in the prior art.

[0006] To achieve the above object, this application provides an exhaust gas purification post-treatment control method, which is applicable to a post-treatment system. The post-treatment system includes: a first nitrogen oxide treatment device, which uses a reducing catalyst and an oxidizing catalyst to reduce nitrogen oxides and oxidize ammonia by injecting urea; a particulate capture device, which uses an oxidizing catalyst to capture particulate matter and nitrides; a second nitrogen oxide treatment device, which uses a reducing catalyst and an oxidizing catalyst to reduce nitrogen oxides and oxidize ammonia by injecting urea; Among them, the control method includes: Calculate the first urea injection amount before the first NOx treatment device and the second urea injection amount before the second NOx based on the first temperature before the first NOx treatment device, the first NOx concentration, the second temperature before the particulate trap device, and the third temperature after it; Control the urea injection of the first NOx treatment device according to the first urea injection amount, and control the urea injection of the second NOx treatment device according to the second urea injection amount; Determine whether the first NOx treatment device triggers the regeneration function based on the total amount of hydrocarbons, total amount of sulfur, actual conversion rate of front-stage NOx, and actual conversion rate of rear-stage NOx of the first NOx treatment device; When it is determined that the first NOx treatment device triggers the regeneration function, calculate the feedforward fuel amount of the first NOx treatment device according to the first temperature before the first NOx treatment device, the target temperature, the exhaust gas mass flow rate, and the exhaust gas specific heat capacity; Inject the fuel of the feedforward fuel amount into the first NOx treatment device, and control the first NOx treatment device to enter the regeneration mode.

[0007] In an embodiment of the present application, the calculating the first urea injection amount before the first NOx treatment device and the second urea injection amount before the second NOx based on the first temperature before the first NOx treatment device, the first NOx concentration, the second temperature before the particulate trap device, and the third temperature after it includes: Calculate the first urea injection amount before the first NOx treatment device according to the first temperature before the first NOx treatment device and the first NOx concentration; Calculate the first concentration ratio of nitrogen dioxide concentration to total NOx concentration before the second NOx treatment device according to the second temperature before the particulate trap device and the third temperature after it; Calculate the second urea injection amount before the second NOx treatment device according to the first concentration ratio of nitrogen dioxide concentration to total NOx concentration before the second NOx treatment device and the third temperature before the second NOx treatment device.

[0008] In an embodiment of the present application, the calculating the first urea injection amount before the first NOx treatment device according to the first temperature before the first NOx treatment device and the first NOx concentration includes: Query the corresponding feedforward NOx conversion efficiency in the first preset data table according to the first temperature before the first NOx treatment device and the space velocity in the first NOx treatment device; wherein, the first preset data table stores preset temperature, preset space velocity, and preset NOx conversion efficiency corresponding to the preset temperature and preset space velocity; Calculate the feedforward nitrogen oxide mass flow rate of the first nitrogen oxide treatment device based on the first nitrogen oxide concentration and the waste gas mass flow rate before the first nitrogen oxide treatment device; Calculate the mass flow rate of hydrogen cyanide based on the feedforward nitrogen oxide mass flow rate of the first nitrogen oxide treatment device; Calculate the first urea injection amount before the first nitrogen oxide treatment device based on the mass flow rate of hydrogen cyanide.

[0009] In an embodiment of the present application, the calculating the first urea injection amount before the first nitrogen oxide treatment device based on the mass flow rate of hydrogen cyanide includes: Calculate the first initial urea injection amount before the first nitrogen oxide treatment device based on the mass flow rate of hydrogen cyanide; Calculate the first temperature difference based on the first temperature before the first nitrogen oxide treatment device and the second temperature after it; Query a correction coefficient corresponding to the first temperature difference in a second preset data table according to the first temperature difference, wherein the second preset data table stores preset temperature differences and preset correction coefficients corresponding to the preset temperature differences; Correct the first initial urea injection amount according to the correction coefficient to obtain the first urea injection amount.

[0010] In an embodiment of the present application, the calculating the first concentration ratio of nitrogen dioxide concentration to total nitrogen oxide concentration before the second nitrogen oxide treatment device based on the second temperature before the particulate trap and the third temperature after it includes: Calculate a weighted temperature value based on the second temperature before the particulate trap and the third temperature after it; Query an initial concentration ratio of nitrogen dioxide concentration to total nitrogen oxide concentration before the second nitrogen oxide treatment device corresponding to the weighted temperature value and the second space velocity of the particulate trap in a third preset data table according to the weighted temperature value and the second space velocity of the particulate trap, wherein the third preset data table stores preset temperature values, preset space velocities, and corresponding preset concentration ratios of nitrogen dioxide concentration to total nitrogen oxide concentration; Correct the initial concentration ratio according to the nitrogen oxide concentration before the particulate trap to obtain the first concentration ratio of nitrogen dioxide concentration to total nitrogen oxide concentration before the second nitrogen oxide treatment device.

[0011] In an embodiment of the present application, the calculating the second urea injection amount before the second nitrogen oxide treatment device based on the first concentration ratio of nitrogen dioxide concentration to total nitrogen oxide concentration before the second nitrogen oxide treatment device and the third temperature before the second nitrogen oxide treatment device includes: The third temperature before the second nitrogen oxide treatment device and the third space velocity of the second nitrogen oxide treatment device are used to query the corresponding nitrogen oxide conversion efficiency in the fourth preset data table; wherein, the fourth preset data table stores preset temperature, preset space velocity, and preset nitrogen oxide conversion efficiency corresponding to the preset temperature and preset space velocity; Correct the nitrogen oxide conversion efficiency of the second nitrogen oxide treatment device according to the first concentration ratio of nitrogen dioxide concentration to total nitrogen oxide concentration before the second nitrogen oxide treatment device; Calculate the second urea injection amount before the second nitrogen oxide treatment device according to the corrected nitrogen oxide conversion efficiency of the second nitrogen oxide treatment device, the waste gas mass, and the nitrogen dioxide concentration before the second nitrogen oxide treatment device.

[0012] In an embodiment of the present application, determining whether the first nitrogen oxide treatment device triggers the regeneration function according to the total hydrocarbon amount, total sulfur amount, actual conversion rate of pre-stage nitrogen oxides, and actual conversion rate of post-stage nitrogen oxides of the first nitrogen oxide treatment device includes: Determine the preset hydrocarbon conversion rate at the average temperature according to the average temperature in the first nitrogen oxide treatment device; calculate the total hydrocarbon amount of the first nitrogen oxide treatment device according to the hydrocarbon amount discharged from the engine, the preset hydrocarbon conversion rate, and the hydrocarbon escape amount stored in the first nitrogen oxide treatment device; Calculate the sulfur storage amount according to the average temperature in the first nitrogen oxide treatment device, and calculate the total sulfur amount according to the sulfur storage amount; When the total hydrocarbon amount of the first nitrogen oxide treatment device is greater than the preset total amount, or the total sulfur amount of the first nitrogen oxide treatment device is greater than the preset poisoning amount, or the actual conversion rate of pre-stage nitrogen oxides is less than the first preset conversion rate; or when the actual conversion rate of post-stage nitrogen oxides is greater than the second preset conversion rate, trigger the regeneration function.

[0013] In an embodiment of the present application, after calculating the feedforward fuel amount of the first nitrogen oxide treatment device according to the first temperature before the first nitrogen oxide treatment device, the target temperature, the waste gas mass flow rate, and the specific heat capacity of the waste gas, the control method further includes: Determine a first correction value according to the target temperature and the waste gas mass flow rate; Correct the feedforward fuel amount according to the first correction value.

[0014] In an embodiment of the present application, after calculating the feedforward fuel amount of the first nitrogen oxide treatment device according to the first temperature before the first nitrogen oxide treatment device, the target temperature, the waste gas mass flow rate, and the specific heat capacity of the waste gas, the control method further includes: Calculate the total hydrocarbon conversion rate according to the hydrocarbon conversion rate of the first nitrogen oxide treatment device and the hydrocarbon conversion rate of the particulate trap device. Modify the feed fuel quantity according to the total hydrocarbon conversion rate to obtain the modified feed fuel quantity.

[0015] As a second aspect of the present application, the present application further provides an exhaust gas purification post-treatment controller, including A first calculation module, configured to calculate a first urea injection quantity before the first nitrogen oxide treatment device and a second urea injection quantity before the second nitrogen oxide according to the first temperature before the first nitrogen oxide treatment device, the first nitrogen oxide concentration, the second temperature before the particulate trap device, and the third temperature after it; A first control module, configured to control the first nitrogen oxide treatment device to inject urea according to the first urea injection quantity, and control the second nitrogen oxide treatment device to inject urea according to the second urea injection quantity; A regeneration control module, configured to determine whether the first nitrogen oxide treatment device triggers a regeneration function according to the total amount of hydrocarbons, the total amount of sulfur, the actual conversion rate of the pre-stage nitrogen oxides, and the actual conversion rate of the post-stage nitrogen oxides of the first nitrogen oxide treatment device; when it is determined that the first nitrogen oxide treatment device triggers the regeneration function, calculate the feed fuel quantity of the first nitrogen oxide treatment device according to the first temperature before the first nitrogen oxide treatment device, the target temperature, the exhaust gas mass flow rate, and the exhaust gas specific heat capacity; and inject the fuel of the feed fuel quantity into the first nitrogen oxide treatment device, and control the first nitrogen oxide treatment device to enter the regeneration mode.

[0016] As a third aspect of the present application, the present application further provides an exhaust gas purification post-treatment system, including: A first nitrogen oxide treatment device, which uses a reducing catalyst and an oxidizing catalyst to reduce nitrogen oxides and oxidize ammonia by injecting urea; A particulate trap device, which uses an oxidizing catalyst to capture particulate matter and nitrides; A second nitrogen oxide treatment device, which uses a reducing catalyst and an oxidizing catalyst to reduce nitrogen oxides and oxidize ammonia by injecting urea; A temperature sensor, configured to detect the temperature of the exhaust gas at different stages; A nitrogen oxide sensor, configured to detect the nitrogen oxide concentration of the exhaust gas at different stages; and The post-treatment controller described above.

[0017] The exhaust gas purification post-treatment control method provided by this application can calculate the feedforward fuel quantity of the first nitrogen oxide treatment device based on the first temperature before the first nitrogen oxide treatment device, the target temperature, the exhaust gas mass flow rate, and the specific heat capacity of the exhaust gas after determining that the first nitrogen oxide treatment device triggers the regeneration function. Then, inject fuel into the first nitrogen oxide treatment device at the feedforward fuel quantity, and then burn it in the first nitrogen oxide treatment device to raise the temperature in the first nitrogen oxide treatment device to the target temperature. When calculating the feedforward fuel quantity, the first temperature before the first nitrogen oxide treatment device is used as the input temperature, and the temperature at the position where the outlet of the particulate trap is located is used as the target temperature to improve the accuracy under transient fuel injection control, make the actual temperature of the particulate trap fit the target temperature, ensure the detoxification of the first-stage nitrogen oxide treatment device and the sufficient oxidation of the particulate matter in the particulate trap, thereby reducing NOx and N2O emissions. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of this application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on the provided drawings.

[0019] Figure 1 It is a schematic structural diagram of an exhaust gas purification post-treatment system provided by an embodiment of this application.

[0020] Figure 2 It is a schematic flowchart of an exhaust gas purification post-treatment control method provided by an embodiment of this application.

[0021] Figure 3 It is a schematic flowchart of an exhaust gas purification post-treatment control method provided by another embodiment of this application.

[0022] Figure 4 It is a schematic flowchart of an exhaust gas purification post-treatment control method provided by another embodiment of this application.

[0023] Figure 5 It is a schematic structural diagram of an exhaust gas purification post-treatment controller provided by another embodiment of this application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] The following will clearly and completely describe the technical solutions in the embodiments of this application with reference to the drawings in the embodiments of this application. Obviously, the described embodiments are only a part of the embodiments of this application, rather than all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of this application.

[0025] For ease of description, some nouns or terms involved in the embodiments of the present application are described below: DPF: Diesel Particulate Filter, which is used to trap particulate matter in the exhaust gas. When the mass of the trapped particulate matter reaches a certain level, passive regeneration or active regeneration is required to restore the particulate matter trapping ability of the DPF. The working principle of the DPF is as follows: NO2 has a strong oxidation ability for the trapped particles. The generated NO2 is used as an oxidant to remove the particles in the particulate trap and generate CO2, while NO2 is reduced to NO, thereby achieving the purpose of removing particles.

[0026] Reaction principle inside the DPF: DOC: Diesel Oxide Catalyst, which is used to convert HC, CO, etc. in the exhaust gas and convert NO in the exhaust gas to NO2. The working principle of the DOC is as follows: At a temperature of 200 - 600 °C, CO and HC are almost completely oxidized to CO2 and H2O, and at the same time, NO is converted to NO2. Reaction principle inside the DOC: DDPF: Integrated Oxidation Trap, which is coated with a catalyst of DOC formulation and a catalyst of DPF formulation in zones, taking into account the functions of both the DPF and the DOC; SCR: Selectively Catalytic Reduction device, where urea is injected before the SCR to reduce nitrogen oxides in the exhaust gas emissions. The working principle of the SCR is as follows: Fuel or an additional reducing agent is injected into the exhaust gas. Using a suitable catalyst, the reaction between the reducing agent and NOx is promoted, while the non-selective oxidation reaction between the reducing agent and oxygen is inhibited. Commonly used urea - SCR catalysts include V2O5 / W2O3 / TiO2 and metal oxides / zeolites. Vanadium-based catalysts have a very high selectivity for NOx and a wide high-efficiency temperature window, and at the same time have high sulfur resistance. The disadvantages are that they are prone to poisoning due to the phosphorus component in the lubricating oil and high-temperature failure; Zeolite-type catalysts have a very strong adsorption ability for NH3, but at low temperatures, the zeolite also has a strong adsorption ability for HC, and the adsorption of HC will affect the low-temperature performance of the catalytic converter. At the same time, the hydrothermal stability and sulfur resistance of the zeolite are poor, so its practical use is limited and low-sulfur content fuels need to be used.

[0027] Oxides of sulfur will form sulfates in the copper-based SCR, reducing the active sites of the catalyst, clogging the small pores, and reducing the conversion efficiency of SCR for NOx. Therefore, when a certain amount of sulfur oxides are trapped in the SCR, desulfurization is required. There are two mechanisms of sulfur poisoning: the formation of (NH4)SO4, etc., reducing the active sites of the SCR catalyst, clogging the small pores, and thus reducing the NOx conversion efficiency; SO2 and SO3 compete for adsorption with NOx, reducing the adsorption of NOx Reaction principle of SCR: Urea hydrolyzes to ammonia: (NH2)2CO + H2O → 2NH3 + CO2 pSCR: Passive Selective Catalytic Reduction device, used to treat nitrogen oxides (NOx).

[0028] ASC: Ammonia Slip Catalyst, used to oxidize excess ammonia.

[0029] As the first aspect of the present application, the present application provides an exhaust gas purification post-treatment system Figure 1 The following is a schematic structural diagram of an exhaust gas purification post-treatment system provided by an embodiment of the present application, as Figure 1 shown, the exhaust gas purification post-treatment system provided by the present application includes: The first nitrogen oxide treatment device A1 uses a reducing catalyst and an oxidizing catalyst to reduce nitrogen oxides and oxidize ammonia by spraying urea from the urea nozzle; the first nitrogen oxide treatment device A1 may include a selective catalytic reduction device SCR and an ammonia slip catalyst ASC, using a reducing catalyst and an oxidizing catalyst to reduce NOx by spraying urea from the Inj1 urea nozzle and oxidize excess NH3.

[0030] The particulate trap device A2 uses an oxidizing catalyst to trap particulates and nitrides; the particulate trap device A2 may include the combination of DOC and DPF; or DDPF or cDPF.

[0031] The second nitrogen oxide treatment device A3 uses a reducing catalyst and an oxidizing catalyst to reduce nitrogen oxides and oxidize ammonia by spraying urea; the second nitrogen oxide treatment device A3 may include SCR and ASC.

[0032] A temperature sensor, used to detect the temperature of the exhaust gas at different stages, such as Figure 1As shown in the figure, the first temperature sensor T1 installed at the inlet of the first nitrogen oxide treatment device A1 can detect the first temperature at the inlet of the waste gas into the first nitrogen oxide treatment device A1; the second temperature sensor T2 installed between the first nitrogen oxide treatment device A1 and the particulate trap A2 can detect the second temperature at the outlet of the first nitrogen oxide treatment device A1; the third temperature sensor installed at the outlet of the particulate trap A2 can detect the third temperature at the outlet of the waste gas from the particulate trap A2.

[0033] A nitrogen oxide sensor is used to detect the nitrogen oxide concentration in the waste gas at different stages; as Figure 1 As shown in the figure, the first nitrogen oxide sensor N1 installed at the inlet of the first nitrogen oxide treatment device A1 can detect the first nitrogen oxide concentration at the inlet of the waste gas into the first nitrogen oxide treatment device A1; the second nitrogen oxide sensor N2 installed between the first nitrogen oxide treatment device A1 and the particulate trap A2 can detect the second nitrogen oxide concentration at the outlet of the first nitrogen oxide treatment device A1; the third nitrogen oxide sensor N3 installed at the outlet of the second nitrogen oxide treatment device A3 can detect the third nitrogen oxide concentration at the outlet of the waste gas from the second nitrogen oxide treatment device A3.

[0034] The aftertreatment system provided by this application uses a first-stage nitrogen oxide treatment device with the functions of reducing NOx and oxidizing HC. According to the poisoning situation, regeneration control is triggered to raise the first-stage nitrogen oxide treatment device to a certain temperature to restore its ability.

[0035] As the second aspect of this application, this application also provides an exhaust gas purification aftertreatment control method for controlling Figure 1 the exhaust gas purification aftertreatment system shown in the figure, Figure 2 As shown in the figure is a schematic flow chart of an exhaust gas purification aftertreatment control method provided by an embodiment of this application. As Figure 2 shown, an exhaust gas purification aftertreatment control method includes the following steps: S1: Calculate the first urea injection amount before the first nitrogen oxide treatment device and the second urea injection amount before the second nitrogen oxide treatment device according to the first temperature before the first nitrogen oxide treatment device, the first nitrogen oxide concentration, the second temperature before the particulate trap, and the third temperature after the particulate trap; The first temperature is detected by the first temperature sensor T1 installed at the inlet of the first nitrogen oxide treatment device A1. The first nitrogen oxide concentration is detected by the first nitrogen oxide sensor N1 installed at the inlet of the first nitrogen oxide treatment device A1. The second temperature is detected by the second temperature sensor T2 installed at the outlet of the first nitrogen oxide treatment device A1 (i.e., the inlet of the particulate trap device A2). The third temperature is detected by the third temperature sensor T3 installed at the outlet of the particulate trap device A2.

[0036] S2: Control the urea injection of the first nitrogen oxide treatment device according to the first urea injection amount, and control the urea injection of the second nitrogen oxide treatment device according to the second urea injection amount; After determining the first urea injection amount, the urea nozzle can be controlled to inject urea into the first nitrogen oxide treatment device A1 according to the first urea injection amount. Similarly, after determining the second urea injection amount, the urea nozzle can be controlled to inject urea into the second nitrogen oxide treatment device A3 according to the second urea injection amount.

[0037] S3: Determine whether the first nitrogen oxide treatment device A1 triggers the regeneration function according to the total amount of hydrocarbons, total amount of sulfur, actual conversion rate of pre-stage nitrogen oxides, and actual conversion rate of post-stage nitrogen oxides of the first nitrogen oxide treatment device A1; Specifically, if any one of the following 4 conditions is met, it can be determined that the first nitrogen oxide treatment device triggers the regeneration function: (1) The total amount of hydrocarbons in the first nitrogen oxide treatment device A1 is greater than the preset total amount; (2) The total amount of sulfur in the first nitrogen oxide treatment device A1 is greater than the preset poisoning amount; (3) The actual conversion rate of pre-stage nitrogen oxides of the first nitrogen oxide treatment device A1 is less than the first preset conversion rate; (4) The actual conversion rate of post-stage nitrogen oxides of the first nitrogen oxide treatment device A1 is greater than the second preset conversion rate.

[0038] S4: When it is determined that the first nitrogen oxide treatment device triggers the regeneration function, calculate the feedforward fuel quantity of the first nitrogen oxide treatment device according to the first temperature before the first nitrogen oxide treatment device, the target temperature, the exhaust gas mass flow rate, and the exhaust gas specific heat capacity; If it is determined in S3 that the first nitrogen oxide treatment device A1 triggers the regeneration function, calculate the feedforward fuel quantity of the first nitrogen oxide treatment device according to the first temperature before the first nitrogen oxide treatment device, the target temperature, the exhaust gas mass flow rate, and the exhaust gas specific heat capacity.

[0039] Among them, the target temperature refers to the target temperature in the first nitrogen oxide treatment device A1. For example, the target temperature can be 450 °C.

[0040] Specifically, the specific calculation formula for the feedforward fuel quantity is: Feedforward fuel quantity = Specific heat capacity of exhaust gas * Mass flow rate of exhaust gas * (Target temperature - First temperature) / Calorific value of fuel.

[0041] S5: Inject the fuel with the feedforward fuel quantity into the first NOx treatment device, and control the first NOx treatment device to enter the regeneration mode.

[0042] After the first NOx treatment device A1 triggers the regeneration function, when the feedforward fuel quantity of the first NOx treatment device is calculated, the first NOx treatment device A1 enters the thermal management mode, injects fuel into the first NOx treatment device A1 at the feedforward fuel quantity, and then burns in the first NOx treatment device A1 to raise the temperature in the first NOx treatment device A1 above the target temperature (for example, the target temperature is 450 °C).

[0043] For the exhaust gas purification post-treatment control method provided in this application, after it is determined that the first NOx treatment device A1 triggers the regeneration function, the feedforward fuel quantity of the first NOx treatment device can be calculated based on the first temperature, target temperature, mass flow rate of exhaust gas, and specific heat capacity of exhaust gas in front of the first NOx treatment device. Then, inject fuel into the first NOx treatment device A1 at the feedforward fuel quantity, and then burn in the first NOx treatment device A1 to raise the temperature in the first NOx treatment device A1 to the target temperature. When calculating the feedforward fuel quantity, the first temperature in front of the first NOx treatment device is used as the input temperature, and the temperature at the position where the outlet of the particulate trap is located is used as the target temperature, which improves the accuracy under transient fuel injection control, makes the actual temperature of the particulate trap fit the target temperature, ensures the detoxification of the first-stage NOx treatment device and the sufficient oxidation of particulate matter in the particulate trap, thereby reducing NOx and N2O emissions.

[0044] In addition, when calculating the feedforward fuel quantity, the first temperature and the target temperature in front of the first NOx treatment device are used. Since the temperature of the first temperature is stable, the calculated feedforward fuel quantity will not deviate greatly, so that the exhaust gas temperature in the first NOx treatment device A1 is uniform. When the exhaust gas enters the particulate trap A2, the oxidation and combustion of particulate matter can be made sufficient, improving the ability of the DPF to capture particulate matter after regeneration, and thus improving the regeneration efficiency.

[0045] In an embodiment of this application, as Figure 3As shown, the specific calculation method for calculating the first urea injection amount before the first nitrogen oxide treatment device A1 and the second urea injection amount before the second nitrogen oxide treatment device A3, that is, S1 (calculating the first urea injection amount before the first nitrogen oxide treatment device and the second urea injection amount before the second nitrogen oxide treatment device according to the first temperature before the first nitrogen oxide treatment device, the first nitrogen oxide concentration, the second temperature before the particulate filter device, and the third temperature after it) specifically includes the following steps: S11: Calculate the first urea injection amount before the first nitrogen oxide treatment device according to the first temperature before the first nitrogen oxide treatment device and the first nitrogen oxide concentration; Specifically, S11 specifically includes the following steps: S110: Query the corresponding feed-forward nitrogen oxide conversion efficiency in the first preset data table according to the first temperature before the first nitrogen oxide treatment device A1 and the space velocity in the first nitrogen oxide treatment device A1; wherein, the first preset data table stores preset temperatures, preset space velocities, and preset nitrogen oxide conversion efficiencies corresponding to the preset temperatures and preset space velocities; Specifically, the space velocity can be calculated by dividing the waste gas mass flow rate by the product of the waste gas density and the volume of the first nitrogen oxide treatment device A1.

[0046] Specifically, the first preset data table is pre-constructed. After determining the first temperature and the space velocity, the corresponding feed-forward nitrogen oxide conversion efficiency can be queried in the first preset data table.

[0047] S111: Calculate the feed-forward nitrogen oxide mass flow rate of the first nitrogen oxide treatment device according to the first nitrogen oxide concentration before the first nitrogen oxide treatment device and the waste gas mass; S112: Calculate the mass flow rate of hydrogen cyanide according to the feed-forward nitrogen oxide mass flow rate of the first nitrogen oxide treatment device and the feed-forward nitrogen oxide conversion efficiency; It is assumed that the reaction of nitrogen oxide and hydrogen cyanide is in a molar ratio of 1:1, and then the mass flow rate of hydrogen cyanide is calculated according to the feed-forward nitrogen oxide mass flow rate.

[0048] S113: Calculate the first urea injection amount before the first nitrogen oxide treatment device according to the mass flow rate of hydrogen cyanide.

[0049] After calculating the mass flow rate of hydrogen cyanide, the first urea injection amount can be calculated according to the mass flow rate of hydrogen cyanide.

[0050] Specifically, S113 (calculating the first urea injection amount before the first nitrogen oxide treatment device according to the mass flow rate of hydrogen cyanide) specifically includes the following steps: S1131: Calculate the first initial urea injection amount before the first nitrogen oxide treatment device according to the mass flow rate of hydrogen cyanide; First, calculate the first initial urea injection amount before the first nitrogen oxide treatment device according to the mass flow rate of hydrogen cyanide.

[0051] S1132: Calculate the first temperature difference according to the first temperature before the first nitrogen oxide treatment device and the second temperature after it; When the first nitrogen oxide treatment device A1 oxidizes HC, it will have an inhibitory effect on the SCR reaction; when the temperature in the first nitrogen oxide treatment device A1 exceeds 400 °C, the oxidation has a significant impact on the NOx reaction. Therefore, it is necessary to correct the urea injection amount according to the temperature difference before and after the first nitrogen oxide treatment device A1.

[0052] S1133: Query the correction coefficient corresponding to the first temperature difference in the second preset data table, where the second preset data table stores preset temperature differences and preset correction coefficients corresponding to the preset temperature differences; Specifically, the second preset data table is pre-constructed, and the second preset data table stores preset temperature differences and corresponding preset correction coefficients.

[0053] After calculating the first temperature difference before and after the first nitrogen oxide treatment device A1, the corresponding correction coefficient can be queried in the second preset data table.

[0054] S1134: Correct the first initial urea injection amount according to the correction coefficient to obtain the first urea injection amount.

[0055] When correcting the first initial urea injection amount, directly multiply the first initial urea injection amount by the correction coefficient.

[0056] This application corrects the urea injection amount through the temperature values before and after the first nitrogen oxide treatment device A1, further accurately controls the urea injection amount, and improves the conversion efficiency.

[0057] S12: Calculate the first concentration ratio of nitrogen dioxide concentration to total nitrogen oxide concentration before the second nitrogen oxide treatment device according to the second temperature before the particulate trap A2 and the third temperature after it; Specifically, S12 (calculate the first concentration ratio of nitrogen dioxide concentration to total nitrogen oxide concentration before the second nitrogen oxide treatment device according to the second temperature before the particulate trap A2 and the third temperature after it) specifically includes the following steps: S120: Calculate the weighted temperature value according to the second temperature before the particulate trap and the third temperature after it; S121: Query the initial concentration ratio of nitrogen dioxide concentration to total nitrogen oxide concentration before the second nitrogen oxide treatment device corresponding to the weighted temperature value and the second airspeed of the particulate trap in a third preset data table, where the third preset data table stores preset temperature values, preset airspeeds, and corresponding preset concentration ratios of nitrogen dioxide concentration to total nitrogen oxide concentration; S122: Modify the initial concentration ratio according to the nitrogen oxide concentration before the particulate trap to obtain the first concentration ratio of nitrogen dioxide concentration to total nitrogen oxide concentration before the second nitrogen oxide treatment device.

[0058] S13: Calculate the second urea injection amount before the second nitrogen oxide treatment device according to the first concentration ratio of nitrogen dioxide concentration to total nitrogen oxide concentration before the second nitrogen oxide treatment device and the third temperature before the second nitrogen oxide treatment device.

[0059] Specifically, S13 (calculating the second urea injection amount before the second nitrogen oxide treatment device according to the first concentration ratio of nitrogen dioxide concentration to total nitrogen oxide concentration before the second nitrogen oxide treatment device and the third temperature before the second nitrogen oxide treatment device) specifically includes the following steps: S131: Query the corresponding nitrogen oxide conversion efficiency in a fourth preset data table based on the third temperature before the second nitrogen oxide treatment device and the third airspeed of the second nitrogen oxide treatment device; where the fourth preset data table stores preset temperatures, preset airspeeds, and preset nitrogen oxide conversion efficiencies corresponding to the preset temperatures and preset airspeeds; S132: Modify the nitrogen oxide conversion efficiency of the second nitrogen oxide treatment device according to the first concentration ratio of nitrogen dioxide concentration to total nitrogen oxide concentration before the second nitrogen oxide treatment device; S132: Calculate the second urea injection amount before the second nitrogen oxide treatment device according to the modified nitrogen oxide conversion efficiency of the second nitrogen oxide treatment device, the waste gas mass, and the nitrogen dioxide concentration before the second nitrogen oxide treatment device.

[0060] In another embodiment of the present application, as Figure 4 shown, S3 (determining whether the first nitrogen oxide treatment device triggers the regeneration function according to the total hydrocarbon amount, total sulfur amount, actual conversion rate of pre-stage nitrogen oxides, and actual conversion rate of post-stage nitrogen oxides of the first nitrogen oxide treatment device A1) specifically includes the following steps: S31: Determine the preset hydrocarbon conversion rate at the average temperature according to the average temperature in the first nitrogen oxide treatment device; calculate the total hydrocarbon amount of the first nitrogen oxide treatment device A1 according to the hydrocarbon amount discharged from the engine, the preset hydrocarbon conversion rate, and the hydrocarbon escape amount stored in the first nitrogen oxide treatment device; Specifically, the average temperature in the first nitrogen oxide treatment device can be calculated as follows: the average temperature is calculated based on the first temperature before the first nitrogen oxide treatment device and the second temperature after the first nitrogen oxide treatment device.

[0061] The hydrocarbon escape amount stored in the first nitrogen oxide treatment device can be obtained by querying a preset data table according to the average temperature.

[0062] The preset hydrocarbon conversion rate can be obtained by querying a preset data table according to the average temperature.

[0063] Specifically, the hydrocarbon amount stored in the first nitrogen oxide treatment device A1 = the hydrocarbon amount discharged from the engine * (1 - preset hydrocarbon conversion rate) - hydrocarbon escape amount; After calculating the hydrocarbon amount stored in the first nitrogen oxide treatment device A1, time integration is performed to obtain the total hydrocarbon amount.

[0064] If the total hydrocarbon amount of the first nitrogen oxide treatment device A1 is greater than the preset total amount, the regeneration function is triggered.

[0065] S32: Calculate the sulfur storage amount according to the average temperature in the first nitrogen oxide treatment device, and calculate the total sulfur amount according to the sulfur storage amount; First, the original sulfur amount is calibrated by the engine speed and fuel quantity, then the sulfur storage amount in the first nitrogen oxide treatment device is calculated according to the average temperature in the first nitrogen oxide treatment device, and then time integration is performed to obtain the total sulfur amount in the first nitrogen oxide treatment device.

[0066] If the total sulfur amount of the first nitrogen oxide treatment device A1 is greater than the preset poisoning amount, the regeneration function is triggered.

[0067] S33: Or when the actual conversion rate of the front-stage nitrogen oxides is less than the first preset conversion rate; or when the actual conversion rate of the rear-stage nitrogen oxides is greater than the second preset conversion rate, the regeneration function is triggered.

[0068] When poisoned by HC or sulfur, the actual conversion efficiency of nitrogen oxides will decrease. In order to maintain the same specific emission, the closed-loop will increase the urea injection amount, resulting in an excessive urea correction amount in the closed-loop. Therefore, by increasing the conversion efficiency to determine whether to trigger the regeneration function, the excessive correction amount of the urea injection amount caused by inaccurate total hydrocarbon amount or total sulfur amount can be reduced.

[0069] When the regeneration function is triggered, the injected fuel burns in the first nitrogen oxide treatment device A1. When the average temperature of the first temperature before the first nitrogen oxide treatment device A1 and the second temperature after it exceeds the target temperature for a certain period of time, it can be considered that desulfurization and de-HC have been completed, and the regeneration function is exited.

[0070] In another embodiment of the present application, after S4 (calculating the feedforward fuel quantity of the first nitrogen oxide treatment device according to the first temperature before the first nitrogen oxide treatment device, the target temperature, the exhaust gas mass flow rate, and the specific heat capacity of the exhaust gas), it is also necessary to correct the feedforward fuel quantity. The specific correction method for correcting the feedforward fuel quantity includes the following methods: (1) Determine the first correction value according to the target temperature and the exhaust gas mass flow rate; specifically, a preset correction table can be pre-constructed. The correction table stores preset temperatures, preset exhaust gas mass flow rates, and corresponding preset correction values. When the target temperature is determined and the exhaust gas mass flow rate is detected, the corresponding first correction value can be queried in the preset correction table.

[0071] Correct the feedforward fuel quantity according to the first correction value. When the first correction value is determined, the first correction value can be directly added to the feedforward fuel quantity to obtain the corrected feedforward fuel quantity.

[0072] (2) Calculate the total hydrocarbon conversion rate according to the hydrocarbon conversion rate of the first nitrogen oxide treatment device and the hydrocarbon conversion rate of the particulate trap; specifically, by calibrating the HC conversion efficiency MAP of the first nitrogen oxide treatment device A1 and the particulate trap A2, calculate the first hydrocarbon conversion efficiency of the first nitrogen oxide treatment device A1 and the second hydrocarbon conversion efficiency of the particulate trap A2, and then calculate the total hydrocarbon conversion rate according to the first hydrocarbon conversion efficiency and the second hydrocarbon conversion efficiency. The total hydrocarbon conversion rate = 1 - (1 - the first hydrocarbon conversion efficiency) * (1 - the second hydrocarbon conversion efficiency).

[0073] Correct the feedforward fuel quantity according to the total hydrocarbon conversion rate to obtain the corrected feedforward fuel quantity. After the total hydrocarbon conversion rate is calculated, the feedforward fuel quantity calculated in S4 is divided by the total hydrocarbon conversion rate to obtain the corrected feedforward fuel quantity.

[0074] After the feedforward fuel quantity is corrected, in S5, the fuel of the corrected feedforward fuel quantity is injected into the first nitrogen oxide treatment device, and the first nitrogen oxide treatment device is controlled to enter the regeneration mode.

[0075] As the third aspect of the present application, the present application also provides an exhaust gas purification post-treatment controller, as Figure 5 shown. The exhaust gas purification post-treatment controller 100 includes: A first calculation module 101, configured to calculate the first urea injection quantity before the first nitrogen oxide and the second urea injection quantity before the second nitrogen oxide according to the first temperature before the first nitrogen oxide treatment device, the first nitrogen oxide concentration, the second temperature before the particulate trap, and the third temperature after it; Specifically, the first calculation module 101 is configured to execute S1 in the above-mentioned exhaust gas purification control method.

[0076] The first control module 102 is configured to control the first NOx treatment device to inject urea according to the first urea injection amount, and control the second NOx treatment device to inject urea according to the second urea injection amount; Specifically, the first control module 102 is configured to execute S2 in the above-described exhaust gas purification post-treatment control method.

[0077] The regeneration control module 103 is configured to determine whether the first NOx treatment device triggers the regeneration function according to the total amount of hydrocarbons, the total amount of sulfur, the actual conversion rate of pre-stage NOx, and the actual conversion rate of post-stage NOx of the first NOx treatment device A1; when it is determined that the first NOx treatment device triggers the regeneration function, calculate the feedforward fuel amount of the first NOx treatment device according to the first temperature, the target temperature, the exhaust gas mass flow rate, and the exhaust gas specific heat capacity in front of the first NOx treatment device; and inject the fuel with the feedforward fuel amount into the first NOx treatment device, and control the first NOx treatment device to enter the regeneration mode.

[0078] Specifically, the regeneration control module 103 is configured to execute S3-S5 in the above-described exhaust gas purification post-treatment control method.

[0079] In the exhaust gas purification post-treatment controller provided in the present application, when calculating the feedforward fuel amount, the first temperature and the target temperature in front of the first NOx treatment device are adopted. Since the temperature of the first temperature is stable, the calculated feedforward fuel amount will not deviate greatly, so that the exhaust gas temperature in the first NOx treatment device A1 is uniform. When the exhaust gas enters the particulate trap A2, the oxidation and combustion of the particulate matter can be made sufficient, the ability of the DPF after regeneration to capture particulate matter is improved, and thus the regeneration efficiency is improved.

[0080] The method in the present application can be implemented in whole or in part by software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer programs or instructions. When the computer program or instructions are loaded and executed on a computer, the processes or functions of the present application are executed in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, a network device, a user device, a core network device, an OAM, or other programmable devices.

[0081] A computer program product may be written in any combination of one or more programming languages to write program code for performing the operations of the embodiments of the present application. The programming languages include object-oriented programming languages such as Java, C++, etc., and also include conventional procedural programming languages such as the "C" language or similar programming languages. The program code may be executed entirely on the user's computing device, partially on the user's device, executed as a stand-alone software package, partially on the user's computing device and partially on a remote computing device, or entirely on a remote computing device or server.

[0082] The computer program or instructions may be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer program or instructions may be transmitted from one website, computer, server, or data center to another website, computer, server, or data center in a wired or wireless manner. The computer-readable storage medium may be any available medium that the computer can access or a data storage device such as a server or data center integrating one or more available media. The available medium may be a magnetic medium, such as a floppy disk, hard disk, or magnetic tape; it may also be an optical medium, such as a digital video disc; or it may be a semiconductor medium, such as a solid-state drive. The computer-readable storage medium may be a volatile or non-volatile storage medium, or may include both volatile and non-volatile types of storage media.

[0083] In addition, an embodiment of the present application may also be a storage medium on which a computer program is stored, and the computer program is executed by a processor to perform the steps in an exhaust gas purification post-treatment control method described in any of the above embodiments of this specification.

[0084] For the foregoing method embodiments, for the sake of simple description, they are all expressed as a series of action combinations. However, those skilled in the art should know that the present application is not limited by the described action sequence, because according to the present application, certain steps may be performed in other sequences or simultaneously. Secondly, those skilled in the art should also know that the embodiments described in the specification are all preferred embodiments, and the actions and modules involved are not necessarily essential to the present application.

[0085] It should be noted that the embodiments in this specification are all described in a progressive manner. Each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments may be referred to each other. For device embodiments, since they are basically similar to the method embodiments, the description is relatively simple, and the relevant parts may refer to the partial description of the method embodiments.

[0086] The steps in the methods of the embodiments of the present application can be adjusted in order, combined, and deleted according to actual needs. The technical features described in the embodiments can be replaced or combined. The devices in the embodiments of the present application can be combined, divided, and deleted according to actual needs.

[0087] Those skilled in the art can further realize that the units and algorithm steps of each example described in combination with the embodiments disclosed herein can be implemented by electronic hardware, computer software, or a combination of the two. To clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described according to functions in the above description. Whether these functions are executed in a hardware or software manner depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of the present application.

[0088] The steps of the methods or algorithms described in combination with the embodiments disclosed herein can be directly implemented by hardware, software units executed by a processor, or a combination of the two. The software units can be placed in a random access memory (RAM), internal memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, removable disk, CD-ROM, or any other form of storage medium well-known in the technical field.

[0089] Finally, it should also be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising a..." does not exclude the existence of additional identical elements in the process, method, article or device including the element.

[0090] 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 obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An exhaust gas purification post-treatment control method, characterized in that, The control method is applicable to a post-treatment system, which includes: a first nitrogen oxide treatment device that uses a reducing catalyst and an oxidizing catalyst to reduce nitrogen oxides by injecting urea and oxidize ammonia; a particulate trap device that uses an oxidizing catalyst to trap particulates and nitrides; a second nitrogen oxide treatment device that uses a reducing catalyst and an oxidizing catalyst to reduce nitrogen oxides by injecting urea and oxidize ammonia; Among them, the control method includes: Calculating a first urea injection amount before the first nitrogen oxide treatment device and a second urea injection amount before the second nitrogen oxide based on the first temperature before the first nitrogen oxide treatment device, the first nitrogen oxide concentration, the second temperature before the particulate trap device, and the third temperature after it; Controlling the urea injection of the first nitrogen oxide treatment device according to the first urea injection amount, and controlling the urea injection of the second nitrogen oxide treatment device according to the second urea injection amount; Determining whether the first nitrogen oxide treatment device triggers a regeneration function based on the total amount of carbon and hydrogen, the total amount of sulfur, the actual conversion rate of nitrogen oxides at the front stage, and the actual conversion rate of nitrogen oxides at the rear stage of the first nitrogen oxide treatment device; When it is determined that the first nitrogen oxide treatment device triggers a regeneration function, calculating the feedforward fuel amount of the first nitrogen oxide treatment device based on the first temperature before the first nitrogen oxide treatment device, the target temperature, the exhaust gas mass flow rate, and the exhaust gas specific heat capacity; Injecting the fuel of the feedforward fuel amount into the first nitrogen oxide treatment device and controlling the first nitrogen oxide treatment device to enter the regeneration mode.

2. The exhaust gas purification post-treatment control method according to claim 1, characterized in that, The calculating the first urea injection amount before the first nitrogen oxide treatment device and the second urea injection amount before the second nitrogen oxide based on the first temperature before the first nitrogen oxide treatment device, the first nitrogen oxide concentration, the second temperature before the particulate trap device, and the third temperature after it includes: Calculating the first urea injection amount before the first nitrogen oxide treatment device based on the first temperature before the first nitrogen oxide treatment device and the first nitrogen oxide concentration; Calculating a first concentration ratio of nitrogen dioxide concentration to total nitrogen oxide concentration before the second nitrogen oxide treatment device based on the second temperature before the particulate trap device and the third temperature after it; Calculating the second urea injection amount before the second nitrogen oxide treatment device based on the first concentration ratio of nitrogen dioxide concentration to total nitrogen oxide concentration before the second nitrogen oxide treatment device and the third temperature before the second nitrogen oxide treatment device.

3. The exhaust gas purification post-treatment control method according to claim 2, wherein The calculating the first urea injection amount before the first nitrogen oxide treatment device based on the first temperature before the first nitrogen oxide treatment device and the first nitrogen oxide concentration includes: Querying the corresponding feedforward nitrogen oxide conversion efficiency in a first preset data table based on the first temperature before the first nitrogen oxide treatment device and the space velocity in the first nitrogen oxide treatment device; wherein, the first preset data table stores preset temperatures, preset space velocities, and preset nitrogen oxide conversion efficiencies corresponding to the preset temperatures and preset space velocities; Calculate the feedforward NOx mass flow rate of the first NOx treatment device based on the first NOx concentration and the exhaust gas mass flow rate before the first NOx treatment device; Calculate the mass flow rate of hydrogen cyanide based on the feedforward NOx mass flow rate of the first NOx treatment device; Calculate the first urea injection amount before the first NOx treatment device based on the mass flow rate of hydrogen cyanide; 4. The exhaust gas purification post-treatment control method according to claim 3, characterized in that The calculating the first urea injection amount before the first NOx treatment device based on the mass flow rate of hydrogen cyanide includes: Calculate the first initial urea injection amount before the first NOx treatment device based on the mass flow rate of hydrogen cyanide; Calculate the first temperature difference based on the first temperature before the first NOx treatment device and the second temperature after it; Query the correction coefficient corresponding to the first temperature difference in the second preset data table according to the first temperature difference, wherein the second preset data table stores preset temperature differences and corresponding preset correction coefficients; Correct the first initial urea injection amount according to the correction coefficient to obtain the first urea injection amount.

5. The exhaust gas purification post-treatment control method according to claim 2, wherein The calculating the first concentration ratio of nitrogen dioxide concentration to total NOx concentration before the second NOx treatment device based on the second temperature before the particulate trap and the third temperature after it includes: Calculate the weighted temperature value based on the second temperature before the particulate trap and the third temperature after it; Query the initial concentration ratio of nitrogen dioxide concentration to total NOx concentration before the second NOx treatment device corresponding to the weighted temperature value and the second space velocity of the particulate trap in the third preset data table, wherein the third preset data table stores preset temperature values, preset space velocities, and corresponding preset concentration ratios of nitrogen dioxide concentration to total NOx concentration; Correct the initial concentration ratio according to the NOx concentration before the particulate trap to obtain the first concentration ratio of nitrogen dioxide concentration to total NOx concentration before the second NOx treatment device.

6. The exhaust gas purification post-treatment control method according to claim 2, characterized in that, The calculating the second urea injection amount before the second NOx treatment device based on the first concentration ratio of nitrogen dioxide concentration to total NOx concentration before the second NOx treatment device and the third temperature before the second NOx treatment device includes: Query the corresponding NOx conversion efficiency in the fourth preset data table based on the third temperature before the second NOx treatment device and the third space velocity of the second NOx treatment device; wherein the fourth preset data table stores preset temperatures, preset space velocities, and corresponding preset NOx conversion efficiencies; Correct the NOx conversion efficiency of the second NOx treatment device according to the first concentration ratio of nitrogen dioxide concentration to total NOx concentration before the second NOx treatment device; Calculate the second urea injection amount before the second NOx treatment device based on the corrected NOx conversion efficiency of the second NOx treatment device, the exhaust gas mass, and the nitrogen dioxide concentration before the second NOx treatment device.

7. The exhaust gas purification post-treatment control method according to claim 1, characterized in that, Determining whether the first nitrogen oxide treatment device triggers the regeneration function according to the total hydrocarbon amount, total sulfur amount, actual conversion rate of the front-stage nitrogen oxides, and actual conversion rate of the rear-stage nitrogen oxides of the first nitrogen oxide treatment device includes: Determining a preset hydrocarbon conversion rate at the average temperature according to the average temperature in the first nitrogen oxide treatment device; calculating the total hydrocarbon amount of the first nitrogen oxide treatment device according to the hydrocarbon amount discharged from the engine, the preset hydrocarbon conversion rate, and the hydrocarbon escape amount stored in the first nitrogen oxide treatment device; Calculating the sulfur storage amount according to the average temperature in the first nitrogen oxide treatment device, and calculating the total sulfur amount according to the sulfur storage amount; When the total hydrocarbon amount of the first nitrogen oxide treatment device is greater than the preset total amount, or the total sulfur amount of the first nitrogen oxide treatment device is greater than the preset poisoning amount, or the actual conversion rate of the front-stage nitrogen oxides is less than the first preset conversion rate; or the actual conversion rate of the rear-stage nitrogen oxides is greater than the second preset conversion rate, trigger the regeneration function.

8. The exhaust gas purification post-treatment control method according to claim 1, characterized in that, After calculating the feedforward fuel amount of the first nitrogen oxide treatment device according to the first temperature before the first nitrogen oxide treatment device, the target temperature, the exhaust gas mass flow rate, and the exhaust gas specific heat capacity, the control method further includes: Determining a first correction value according to the target temperature and the exhaust gas mass flow rate; Correcting the feedforward fuel amount according to the first correction value.

9. The exhaust gas purification post-treatment control method according to claim 1, characterized in that After calculating the feedforward fuel amount of the first nitrogen oxide treatment device according to the first temperature before the first nitrogen oxide treatment device, the target temperature, the exhaust gas mass flow rate, and the exhaust gas specific heat capacity, the control method further includes: Calculating the total hydrocarbon conversion rate according to the hydrocarbon conversion rate of the first nitrogen oxide treatment device and the hydrocarbon conversion rate of the particulate trap; Correcting the feedforward fuel amount according to the total hydrocarbon conversion rate to obtain the corrected feedforward fuel amount.

10. An exhaust gas purification post-treatment controller, characterized in that, Including A first calculation module for calculating the first urea injection amount before the first nitrogen oxide treatment device and the second urea injection amount before the second nitrogen oxides according to the first temperature before the first nitrogen oxide treatment device, the first nitrogen oxide concentration, the second temperature before the particulate trap, and the third temperature after; A first control module for controlling the first nitrogen oxide treatment device to inject urea according to the first urea injection amount, and controlling the second nitrogen oxide treatment device to inject urea according to the second urea injection amount; A regeneration control module for determining whether the first nitrogen oxide treatment device triggers the regeneration function according to the total hydrocarbon amount, total sulfur amount, actual conversion rate of the front-stage nitrogen oxides, and actual conversion rate of the rear-stage nitrogen oxides of the first nitrogen oxide treatment device; when it is determined that the first nitrogen oxide treatment device triggers the regeneration function, calculating the feedforward fuel amount of the first nitrogen oxide treatment device according to the first temperature before the first nitrogen oxide treatment device, the target temperature, the exhaust gas mass flow rate, and the exhaust gas specific heat capacity; and injecting the fuel of the feedforward fuel amount into the first nitrogen oxide treatment device, and controlling the first nitrogen oxide treatment device to enter the regeneration mode.

11. An exhaust gas purification post-treatment system, characterized in that, Including: The first nitrogen oxide treatment device, which uses a reducing catalyst and an oxidizing catalyst to reduce nitrogen oxides with the injected urea and oxidize ammonia; A particulate trap that uses an oxidation catalyst to trap particulates and nitrides; A second nitrogen oxide treatment device that uses a reduction catalyst and an oxidation catalyst to reduce nitrogen oxides and oxidize ammonia by injecting urea; A temperature sensor for detecting the temperature of the exhaust gas at different stages; A nitrogen oxide sensor for detecting the nitrogen oxide concentration of the exhaust gas at different stages; and The aftertreatment controller according to claim 10.

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