An after-treatment system, method and vehicle

Abstract

This application discloses an aftertreatment system, method, and vehicle that can achieve lower emissions while maintaining a substantially unchanged aftertreatment installation space. The aftertreatment system includes: a first nitrogen oxide (NOx) treatment device for reducing NOx and oxidizing and removing it with ammonia; a particulate matter treatment device for capturing particulate matter and catalytically generating nitrogen dioxide; a second NOx treatment device for reducing NOx and oxidizing and removing it with ammonia; a urea nozzle for injecting urea; a temperature sensor for detecting temperature; and a NOx sensor for detecting NOx concentration.

Description

Technical Field

[0001] This application relates to the field of emission control technology, specifically to an aftertreatment system, method, and vehicle. Background Technology

[0002] As the development of new-generation emission standards progresses, more stringent comprehensive control requirements have been imposed on exhaust emissions. On the one hand, emission limits for nitrogen oxides (NOx) and particulate matter (PN) need to be further reduced; on the other hand, new control indicators for nitrous oxide (N2O) emissions have been added. However, the existing aftertreatment system architecture has already been finalized based on previous emission standards, with its carrier layout space, catalyst coating amount, and temperature control strategy all fixed. When meeting the upgraded emission control requirements, traditional technical solutions, by simply increasing the catalyst dosage or extending the aftertreatment process, inevitably lead to a significant increase in system size. This increased aftertreatment system size not only makes vehicle chassis layout difficult but also significantly increases development costs due to the need to redesign the exhaust system routing and adjust suspension system parameters. Summary of the Invention

[0003] To address the aforementioned technical problems, this application is proposed. Embodiments of this application provide an aftertreatment system, method, and vehicle that can achieve lower emissions while maintaining a substantially unchanged aftertreatment installation space.

[0004] According to a first aspect of this application, an aftertreatment system is provided, comprising: a first nitrogen oxide treatment device located downstream of the exhaust outlet of an engine, the first nitrogen oxide treatment device being used to reduce nitrogen oxides and perform ammonia oxidation removal; a particulate matter treatment device located downstream of the first nitrogen oxide treatment device, the particulate matter treatment device being used to capture particulate matter and catalytically generate nitrogen dioxide; a second nitrogen oxide treatment device located downstream of the particulate matter treatment device, the second nitrogen oxide treatment device being used to reduce nitrogen oxides and perform ammonia oxidation removal; a urea nozzle for spraying urea into the first nitrogen oxide treatment device and the second nitrogen oxide treatment device; a temperature sensor for detecting the temperature before the intake end of the first nitrogen oxide treatment device, the temperature before the intake end of the particulate matter treatment device, and the temperature before the intake end of the second nitrogen oxide treatment device; and a nitrogen oxide sensor for detecting the nitrogen oxide concentration at the intake end of the first nitrogen oxide treatment device, the nitrogen oxide concentration at the outlet end of the first nitrogen oxide treatment device, and the nitrogen oxide concentration at the outlet end of the second nitrogen oxide treatment device.

[0005] As one possible implementation, the first nitrogen oxide treatment device is coated with a selective catalytic reduction catalyst and an ammonia escape catalyst, and the second nitrogen oxide treatment device is coated with a selective catalytic reduction catalyst and an ammonia escape catalyst.

[0006] As one possible implementation, the particulate matter treatment device is coated with a catalyst formulated for an oxidation catalytic converter and a catalyst formulated for a particulate matter trap.

[0007] According to a second aspect of this application, a control method for an aftertreatment system is provided, applied to the aftertreatment system described in the first aspect or any implementation thereof. The control method for the aftertreatment system includes: calculating the urea injection quantity of the first nitrogen oxide treatment device based on exhaust gas data, the nitrogen oxide concentration at the inlet of the first nitrogen oxide treatment device, the temperature before the inlet of the first nitrogen oxide treatment device, and the space velocity of the first nitrogen oxide treatment device; and adjusting the urea injection quantity injected into the first nitrogen oxide treatment device based on the nitrogen oxide concentration at the outlet of the first nitrogen oxide treatment device, the temperature before the inlet of the first nitrogen oxide treatment device, and a preset nitrogen oxide emission ratio. Based on the temperature before the inlet of the particulate matter treatment device, the temperature before the inlet of the second nitrogen oxide treatment device, and the air velocity of the particulate matter treatment device, calculate the ratio of nitrogen dioxide to nitrogen oxides output by the particulate matter treatment device; based on the nitrogen oxide concentration at the outlet of the first nitrogen oxide treatment device, the temperature before the inlet of the second nitrogen oxide treatment device, and the ratio of nitrogen dioxide to nitrogen oxides output by the particulate matter treatment device, calculate the urea injection rate of the second nitrogen oxide treatment device; based on the nitrogen oxide concentration at the outlet of the second nitrogen oxide treatment device and the second preset nitrogen oxide emission ratio, adjust the urea injection rate injected into the second nitrogen oxide treatment device.

[0008] As one possible implementation, the urea injection quantity of the first nitrogen oxide treatment device is calculated based on exhaust gas data, the nitrogen oxide concentration at the inlet of the first nitrogen oxide treatment device, the temperature before the inlet of the first nitrogen oxide treatment device, and the space velocity of the first nitrogen oxide treatment device. This includes: determining the nitrogen oxide conversion efficiency of the first nitrogen oxide treatment device based on the temperature before the inlet of the first nitrogen oxide treatment device and the space velocity of the first nitrogen oxide treatment device; and calculating the urea injection quantity of the first nitrogen oxide treatment device based on exhaust gas data, the nitrogen oxide concentration at the inlet of the first nitrogen oxide treatment device, and the nitrogen oxide conversion efficiency of the first nitrogen oxide treatment device.

[0009] As one possible implementation, adjusting the urea injection amount into the first nitrogen oxide treatment device based on the nitrogen oxide concentration at the outlet of the first nitrogen oxide treatment device, the temperature before the inlet of the first nitrogen oxide treatment device, and a preset nitrogen oxide ratio emission includes: calculating the actual nitrogen oxide ratio emission of the first nitrogen oxide treatment device based on the nitrogen oxide concentration at the outlet of the first nitrogen oxide treatment device and the exhaust gas data; when the actual nitrogen oxide ratio emission of the first nitrogen oxide treatment device exceeds the emission range of the first preset nitrogen oxide ratio emission, adjusting the urea injection amount of the first nitrogen oxide treatment device based on the deviation between the actual nitrogen oxide ratio emission of the first nitrogen oxide treatment device and the first preset nitrogen oxide ratio emission.

[0010] As one possible implementation, the ratio of nitrogen dioxide to nitrogen oxides output by the particulate matter treatment device is calculated based on the temperature before the inlet of the particulate matter treatment device, the temperature before the inlet of the second nitrogen oxide treatment device, and the space velocity of the particulate matter treatment device. This includes: obtaining a weighted temperature value based on the temperature before the inlet of the particulate matter treatment device and the temperature before the inlet of the second nitrogen oxide treatment device; determining a preset ratio of nitrogen dioxide to nitrogen oxides based on the weighted temperature value and the space velocity of the particulate matter treatment device; and calculating the ratio of nitrogen dioxide to nitrogen oxides output by the particulate matter treatment device based on the nitrogen oxide concentration at the outlet of the first nitrogen oxide treatment device and the preset ratio of nitrogen dioxide to nitrogen oxides.

[0011] As one possible implementation, adjusting the urea injection amount into the second nitrogen oxide treatment device based on the nitrogen oxide concentration at the outlet of the second nitrogen oxide treatment device and the second preset nitrogen oxide ratio emission includes: calculating the actual nitrogen oxide ratio emission of the second nitrogen oxide treatment device based on the nitrogen oxide concentration at the outlet of the second nitrogen oxide treatment device and the exhaust gas data; when the actual nitrogen oxide ratio emission of the second nitrogen oxide treatment device exceeds the emission range of the second preset nitrogen oxide ratio emission, adjusting the urea injection amount of the second nitrogen oxide treatment device based on the deviation between the actual nitrogen oxide ratio emission of the second nitrogen oxide treatment device and the second preset nitrogen oxide ratio emission.

[0012] As one possible implementation, the control method of the aftertreatment system further includes: calculating the carbon load based on a first pressure difference of the particulate matter treatment device and the exhaust gas data; wherein the first pressure difference represents the differential pressure between the inlet and outlet of the particulate matter treatment device; adjusting the urea injection quantity and temperature when the carbon load is greater than or equal to a first limit; and triggering a parking regeneration request when the carbon load is greater than or equal to a second limit; wherein the second limit is greater than the first limit.

[0013] According to a third aspect of this application, a vehicle is provided, comprising: an engine; an aftertreatment system as described in the first aspect or any implementation thereof, the aftertreatment system being located downstream of the engine's exhaust outlet; and a controller communicatively connected to the aftertreatment system, the controller being configured to control the aftertreatment system to perform a control method for the aftertreatment system as described in the second aspect or any implementation thereof.

[0014] The aftertreatment system, method, and vehicle provided in this application simultaneously reduce nitrogen oxides and oxidize and remove ammonia by arranging a multifunctional catalyst in a first nitrogen oxide treatment device and combining it with urea injected through a urea nozzle. In a particulate matter treatment device, a multifunctional catalyst captures particulate matter and catalyzes the generation of nitrogen dioxide. In a second nitrogen oxide treatment device, urea injected through a urea nozzle further reduces nitrogen oxides and oxidizes and removes ammonia. The multifunctional catalyst design maintains a relatively constant aftertreatment installation space. Furthermore, by monitoring temperature with a temperature sensor and nitrogen oxide concentration at each stage with a nitrogen oxide sensor, the injection volume of the urea nozzle can be flexibly adjusted to prevent waste of reducing agent and reduce the possibility of secondary pollution caused by ammonia leakage after catalyst catalysis, thereby achieving lower emissions. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the structure of a post-processing system provided in an exemplary embodiment of this application.

[0017] Figure 2 This is a flowchart illustrating a control method for a post-processing system provided in an exemplary embodiment of this application.

[0018] Figure 3 This is a schematic diagram of the structure of a control device for a post-processing system provided in an exemplary embodiment of this application.

[0019] Explanation of reference numerals in the attached drawings: A1 - First nitrogen oxide treatment device; A2 - Particulate matter treatment device; A3 - Second nitrogen oxide treatment device; N1 - First nitrogen oxide sensor; N2 - Second nitrogen oxide sensor; N3 - Third nitrogen oxide sensor; T1 - First temperature sensor; T2 - Second temperature sensor; T3 - Third temperature sensor; Inj1 - First urea nozzle; Inj2 - Second urea nozzle. Detailed Implementation

[0020] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0021] With the continuous tightening of emission control requirements for internal combustion engines, restrictions on pollutants such as nitrogen oxides (NOx) and particulate matter (PN) are becoming increasingly stringent, while nitrous oxide (N2O) emissions monitoring has also been added. Against this backdrop, vehicle emission testing conditions have been further optimized, placing greater emphasis on pollutant control capabilities under real-world driving conditions. However, the design space for current vehicle after-treatment systems has become relatively fixed, especially with the layout of after-treatment devices largely finalized for the China VI emission standard. If a newly developed after-treatment system is significantly larger, the limited space in the engine compartment makes it difficult to rationally arrange an excessively large after-treatment device within the existing chassis architecture, potentially affecting vehicle assembly or even causing structural interference. Redesigning the exhaust system or adjusting the layout of surrounding components would significantly increase material, verification, and production line modification costs.

[0022] Based on the problems mentioned above Figure 1 This is a schematic diagram of the structure of a post-processing system provided in an exemplary embodiment of this application, to... Figure 1 For reference, the specific structure of the post-processing system is described in detail.

[0023] First, the aftertreatment system includes a first nitrogen oxide (NOx) treatment device A1, located downstream of the engine's exhaust outlet. The first NOx treatment device A1 is used to reduce NOx and remove it by ammonia oxidation. Between the first NOx treatment device A1 and the downstream of the exhaust outlet, there are a first temperature sensor T1, a first urea nozzle Inj1, and a first NOx sensor N1. The first temperature sensor T1 is located at the intake end of the first NOx treatment device A1 and is used to detect the temperature before the intake end of the first NOx treatment device A1. The first urea nozzle Inj1 is located at the intake end of the first NOx treatment device A1 and downstream of the first temperature sensor T1, and is used to spray urea into the first NOx treatment device A1. The first NOx sensor N1 is located at the intake end of the first NOx treatment device A1 and downstream of the first urea nozzle Inj1, and is used to detect the NOx concentration at the intake end of the first NOx treatment device A1.

[0024] The first nitrogen oxide treatment unit A1 is coated with a selective catalyst reduction (SCR) catalyst and an ammonia slip catalyst (ASC):

[0025] SCR catalysts are primarily used to remove NOx (nitrogen oxides, including NO and NO2) from exhaust gases. This is achieved by injecting fuel into the exhaust or adding a reducing agent. A suitable catalyst promotes the reaction between the reducing agent and NOx while inhibiting the non-selective oxidation reaction between the reducing agent and oxygen. Commonly used urea-SCR catalysts include V2O5 / W2O3 / TiO2 and metal oxide / zeolite catalysts. Vanadium-based catalysts exhibit high selectivity for NOx and a wide efficient temperature window, along with high sulfur resistance. Zeolite catalysts have a strong adsorption capacity for NH3. Furthermore, sulfur oxides in copper-based SCRs form sulfates, reducing catalyst active sites, clogging pores, and decreasing the SCR's NOx conversion efficiency. Therefore, once a certain amount of sulfur oxides is captured within the SCR, desulfurization is necessary.

[0026] The reaction principle of SCR technology:

[0027] Urea hydrolyzes to ammonia: (NH2)2CO + H2O → 2NH3 + CO2

[0028] SCR post-treatment reaction:

[0029] NO + NO₂ + 2NH₃ → 2N₂ + 3H₂O

[0030] 4NO + O2 + 4NH3 → 4N2 + 6H2O

[0031] 2NO2 + O2 + 4NH3 → 3N2 + 6H2O

[0032] In SCR (Selective Catalytic Reduction), the actual reducing agent participating in the selective catalytic reduction reaction is ammonia (NH3). However, due to the high corrosiveness of ammonia, liquid ammonia and ammonia water present difficulties in storage and transportation, and therefore cannot be directly used in vehicle-mounted SCR systems. Currently, urea aqueous solution is generally used as the reducing agent. Furthermore, because a 32.5% urea aqueous solution has the lowest freezing point of -11℃ compared to other concentrations, it is widely used as the standard reducing agent for SCR and is named AdBlue.

[0033] Since SCR catalysts may escape NH3 due to excessive urea injection or low temperature, an ammonia slip catalyst (ASC) is installed to reduce the secondary pollution that may be caused by ammonia leakage. The ASC oxidizes the escaped ammonia to generate harmless nitrogen (N2) and water (H2O), preventing ammonia from being directly released into the atmosphere (NH3 itself is irritating and may form secondary particulate matter).

[0034] The main chemical reactions of ASC are:

[0035] Ideally, NH3 is selectively oxidized to N2:

[0036] 4NH3 + 3O2 → 2N2 + 6H2O

[0037] N2O generation inhibition:

[0038] 2NH3 + 2O2 → N2O + 3H2O

[0039] Therefore, the selective catalytic reduction catalyst and ammonia escape catalyst coated in the first nitrogen oxide treatment device A1, combined with the urea injected by the first urea nozzle Inj1, reduce nitrogen oxides in the exhaust gas and remove ammonia by oxidation.

[0040] The post-treatment system further includes a particulate matter treatment device A2, located downstream of the first nitrogen oxide treatment device A1. The particulate matter treatment device A2 is used to capture particulate matter and catalytically generate nitrogen dioxide. A second temperature sensor T2 and a second nitrogen oxide sensor N2 are disposed between the particulate matter treatment device A2 and the first nitrogen oxide treatment device A1. The second nitrogen oxide sensor N2 is located at the outlet of the first nitrogen oxide treatment device A1, or at the inlet of the particulate matter treatment device A2. The second nitrogen oxide sensor N2 is used to detect the nitrogen oxide concentration at the outlet of the first nitrogen oxide treatment device A1, or at the inlet of the particulate matter treatment device A2. The second temperature sensor T2 is located downstream of the second nitrogen oxide sensor N2. The second temperature sensor T2 is used to detect the temperature before the inlet of the particulate matter treatment device A2, or can be understood as the temperature at the outlet of the first nitrogen oxide treatment device A1.

[0041] The A2 particulate matter treatment unit is coated with catalysts from both the oxidation catalytic converter and particulate matter trap formulations. The catalyst in the oxidation catalytic converter formulation is an oxidation-type catalyst. For example, the particulate matter catalyst oxidation catalysis (DOC) technology involves coating a noble metal catalyst (such as Pt) onto a honeycomb ceramic support. Its purpose is to lower the activation energy of the chemical reactions of HC, CO, and SOF in engine exhaust, allowing these substances to react with oxygen in the exhaust at a lower temperature and ultimately convert into CO2 and H2O. Oxidation-type catalytic converters do not require regeneration systems or control devices, and are characterized by simple structure and high reliability.

[0042] Diesel Particulate Filter (DPF) technology primarily filters and captures particulate matter in engine exhaust through diffusion, deposition, and impaction mechanisms. As exhaust flows through the filter, particulate matter is trapped within the filter element, leaving relatively clean exhaust to be released into the atmosphere. The catalyst in the DPF works by oxidizing the exhaust (DOC) at temperatures of 200-600°C, where CO and HC are almost entirely oxidized to CO2 and H2O, while NO is converted to NO2. After exiting the DOC and entering the DPF catalyst, the particulate matter is again trapped within the filter element, leaving relatively clean exhaust to be released into the atmosphere.

[0043] NO2 has a strong oxidizing ability on the captured particles. The generated NO2 is used as an oxidant to remove particles from the particulate trap and generate CO2. The NO2 is then reduced to NO, thereby achieving the purpose of removing particles.

[0044] Therefore, the reaction principle of the catalyst in the oxidation catalytic converter formulation in particulate matter treatment unit A2 is as follows:

[0045] 2NO + O2 → 2NO2

[0046] 2CO + O2 → 2CO2

[0047] 2CH + O2 → CO2 + H2O

[0048] The reaction principle of the catalyst in the particulate matter trap formulation is as follows:

[0049] C + 2NO₂ → CO₂ + 2NO

[0050] Finally, the after-treatment system also includes a second nitrogen oxide treatment device A3, located downstream of the particulate matter treatment device A2. The second nitrogen oxide treatment device A3 is used to reduce nitrogen oxides and perform ammonia oxidation removal. A third temperature sensor T3 and a second urea nozzle Inj2 are installed between the second nitrogen oxide treatment device A3 and the particulate matter treatment device A2. The third temperature sensor T3 is located at either the inlet of the second nitrogen oxide treatment device A3 or the outlet of the particulate matter treatment device A2, and is used to detect the temperature before the inlet of the second nitrogen oxide treatment device A3. The second urea nozzle Inj2 is located downstream of the third temperature sensor T3 and at the inlet of the second nitrogen oxide treatment device A3, and is used to spray urea into the second nitrogen oxide treatment device A3. Furthermore, a third nitrogen oxide sensor N3 is also located downstream of the second nitrogen oxide treatment device A3, and is used to detect the nitrogen oxide concentration at the outlet of the second nitrogen oxide treatment device A3. The second nitrogen oxide treatment unit A3 is coated with the same selective catalytic reduction catalyst and ammonia slip catalyst as the first nitrogen oxide treatment unit A1. Therefore, the reaction principle in the second nitrogen oxide treatment unit A3 is the same as that in the first nitrogen oxide treatment unit A1. Since the regeneration process of the particulate matter treatment unit A2 may cause significant fluctuations in exhaust gas temperature, these temperature changes may temporarily cause the upstream SCR catalyst to deviate from its optimal operating temperature window, leading to a decrease in nitrogen oxide conversion efficiency. Therefore, the addition of the second nitrogen oxide treatment unit A3, which injects additional urea, compensates for the potential temperature fluctuations or uneven ammonia distribution problems that may occur after the regeneration of the particulate matter treatment unit A2, thereby achieving lower emissions.

[0051] Based on the structure of the aftertreatment system proposed above, lower emissions can be achieved through appropriate catalyst design and aftertreatment control while maintaining a relatively constant aftertreatment installation space. Therefore, a control method for the aftertreatment system is proposed below, which can achieve lower emissions and higher environmental performance based on the structure of this aftertreatment system. Figure 2 This is a flowchart illustrating the control method of a post-processing system provided in an exemplary embodiment of this application. The following is in conjunction with... Figure 2 The control method of the post-processing system provided in the embodiments of this application will be described in more detail.

[0052] First, based on the exhaust gas data, the nitrogen oxide concentration at the inlet of the first nitrogen oxide treatment device, the temperature before the inlet of the first nitrogen oxide treatment device, and the space velocity of the first nitrogen oxide treatment device, calculate the urea injection rate of the first nitrogen oxide treatment device (see...). Figure 2 (S210).

[0053] In some embodiments, exhaust gas data includes exhaust gas-related data such as exhaust gas density and exhaust gas mass.

[0054] In some embodiments, the nitrogen oxide conversion efficiency of the first nitrogen oxide treatment device can be determined based on the temperature before the inlet of the first nitrogen oxide treatment device and the space velocity of the first nitrogen oxide treatment device. The space velocity is calculated by dividing the exhaust gas mass flow rate by the exhaust gas density and the volume of the first nitrogen oxide treatment device. For example, the theoretical conversion efficiency of the selective catalytic reduction (SCR) for nitrogen oxides (NOx) under the current operating conditions can be calculated in real time using the catalyst characteristic curve (MAP) built into the aftertreatment system, with the temperature before the inlet and the space velocity as input parameters. This MAP is constructed based on a large amount of experimental data and reflects the performance limits of the catalyst under different boundary conditions. Obtaining the nitrogen oxide conversion efficiency of the first nitrogen oxide treatment device provides a data basis for subsequent adjustment of the urea injection rate. Then, the urea injection rate of the first nitrogen oxide treatment device can be calculated based on the exhaust gas data (e.g., exhaust gas mass), the nitrogen oxide concentration at the inlet of the first nitrogen oxide treatment device, and the nitrogen oxide conversion efficiency of the first nitrogen oxide treatment device. After calculating the actual urea injection rate, the actual urea injection rate can be adjusted according to needs, such as increasing or decreasing, to avoid excessive urea waste or insufficient urea leading to incomplete reaction.

[0055] Second, based on the nitrogen oxide concentration at the outlet of the first nitrogen oxide treatment device, the temperature before the inlet of the first nitrogen oxide treatment device, and the preset nitrogen oxide emission ratio, adjust the urea injection rate into the first nitrogen oxide treatment device (see [reference]). Figure 2 (S220).

[0056] In some embodiments, the actual nitrogen oxide ratio emission of the first nitrogen oxide treatment device is calculated based on the nitrogen oxide concentration, exhaust gas mass flow rate, and power at the outlet of the first nitrogen oxide treatment device; when the actual nitrogen oxide ratio emission of the first nitrogen oxide treatment device exceeds the emission range of the first preset nitrogen oxide ratio emission, the urea injection quantity of the first nitrogen oxide treatment device is adjusted based on the deviation between the actual nitrogen oxide ratio emission of the first nitrogen oxide treatment device and the first preset nitrogen oxide ratio emission.

[0057] One possible way to adjust the urea injection rate of the first nitrogen oxide treatment unit is to preset a first nitrogen oxide emission ratio (e.g., 7 g / kWh). When the first preset nitrogen oxide emission ratio is greater than the actual nitrogen oxide emission ratio, the PI controller uses the deviation between the actual and preset nitrogen oxide emission ratios to reduce the urea injection rate. When the first preset nitrogen oxide emission ratio is less than the actual nitrogen oxide emission ratio, the PI controller uses the deviation between the actual and preset nitrogen oxide emission ratios to increase the urea injection rate. When the first preset nitrogen oxide emission ratio is equal to the actual nitrogen oxide emission ratio, the urea injection rate does not need to be adjusted.

[0058] Dynamically adjusting the urea injection rate of the first nitrogen oxide treatment unit can improve NOx conversion efficiency, optimize urea utilization, reduce ammonia slip, extend catalyst life, and enhance the reliability of the first nitrogen oxide treatment unit.

[0059] Third, based on the temperatures before the inlet of the particulate matter treatment unit, the temperatures before the inlet of the second nitrogen oxide treatment unit, and the space velocity of the particulate matter treatment unit, calculate the ratio of nitrogen dioxide to nitrogen oxides output by the particulate matter treatment unit (see [reference]). Figure 2 (S230).

[0060] In some embodiments, a weighted temperature value can first be obtained based on the temperatures before the inlet of the particulate matter treatment device and the inlet of the second nitrogen oxide treatment device. Then, a preset nitrogen dioxide to nitrogen oxide ratio (NO2 / NOx ratio) is determined based on the weighted temperature value and the space velocity of the particulate matter treatment device. For example, the basic nitrogen dioxide to nitrogen oxide ratio (preset nitrogen dioxide to nitrogen oxide ratio) can be obtained by looking up the MAP (Magnetic Mapping Index) based on the weighted temperature value and the space velocity of the particulate matter treatment device. Finally, the nitrogen dioxide to nitrogen oxide ratio output by the particulate matter treatment device is calculated based on the nitrogen oxide concentration at the outlet of the first nitrogen oxide treatment device and the preset nitrogen dioxide to nitrogen oxide ratio. The nitrogen dioxide to nitrogen oxide ratio output by the particulate matter treatment device can be used as reference data for adjusting the urea injection rate of the subsequent second nitrogen oxide treatment device to achieve low-emission environmentally friendly aftertreatment.

[0061] Fourth, based on the nitrogen oxide concentration at the outlet of the first nitrogen oxide treatment device, the temperature before the inlet of the second nitrogen oxide treatment device, and the ratio of nitrogen dioxide to nitrogen oxides output by the particulate matter treatment device, calculate the urea injection rate of the second nitrogen oxide treatment device (see...). Figure 2 (S240).

[0062] In some embodiments, the NOx conversion efficiency can be determined first by referring to the MAP (Modular Mapping Index) based on the temperature and space velocity before the inlet of the second NOx treatment device, and then the NOx conversion efficiency can be corrected based on the ratio of nitrogen dioxide to nitrogen oxides. Finally, the urea injection rate before the second NOx treatment device is calculated based on the exhaust gas mass flow rate, the NOx concentration at the inlet of the first NOx treatment device, and the conversion efficiency. The space velocity is calculated by dividing the exhaust gas mass flow rate by the product of the exhaust gas density and the volume of the second NOx treatment device.

[0063] Fifth, based on the nitrogen oxide concentration at the outlet of the second nitrogen oxide treatment device and the second preset nitrogen oxide emission ratio, adjust the urea injection rate into the second nitrogen oxide treatment device (see...). Figure 2 (S250).

[0064] In some embodiments, after calculating the actual urea injection rate before the second nitrogen oxide treatment device, a second preset nitrogen oxide emission ratio (e.g., 0.1 g / kWh) is preset for the second nitrogen oxide treatment device. The actual nitrogen oxide emission ratio of the second nitrogen oxide treatment device is calculated based on the nitrogen oxide concentration at the outlet of the second nitrogen oxide treatment device, the exhaust gas mass flow rate, and the power. When the actual nitrogen oxide emission ratio of the second nitrogen oxide treatment device exceeds the emission range of the second preset nitrogen oxide emission ratio, the urea injection rate of the second nitrogen oxide treatment device is adjusted based on the deviation between the actual nitrogen oxide emission ratio and the second preset nitrogen oxide emission ratio.

[0065] As one possible way to adjust the urea injection rate of the second nitrogen oxide treatment unit, when the second preset nitrogen oxide emission ratio is greater than the actual nitrogen oxide emission ratio of the second nitrogen oxide treatment unit, the PI controller reduces the urea injection rate based on the deviation between the actual and preset nitrogen oxide emission ratios. When the second preset nitrogen oxide emission ratio is less than the actual nitrogen oxide emission ratio of the second nitrogen oxide treatment unit, the PI controller increases the urea injection rate based on the deviation between the actual and preset nitrogen oxide emission ratios. When the second preset nitrogen oxide emission ratio is equal to the actual nitrogen oxide emission ratio of the second nitrogen oxide treatment unit, the urea injection rate is not adjusted.

[0066] Dynamically adjusting the urea injection rate of the second nitrogen oxide treatment unit reduces urea consumption, improves urea utilization, and lowers ammonia leakage, thereby enhancing SCR treatment efficiency and optimizing ASC workload. Extending catalyst life and reducing urea consumption also extends the service life of the second nitrogen oxide treatment unit, thus reducing operating costs.

[0067] Furthermore, because the particulate matter treatment unit uses a multi-functional catalyst, its passive regeneration effect is slightly inferior compared to independent DOC and DPF functions. To ensure the same level of regeneration effect, the carbon load can be calculated based on the first differential pressure and exhaust gas data of the particulate matter treatment unit. The first differential pressure represents the pressure difference between the inlet and outlet of the particulate matter treatment unit. When the carbon load is greater than or equal to a first limit, the urea injection quantity and temperature are adjusted. When the carbon load is greater than or equal to a second limit, a parking regeneration request is triggered. The second limit is greater than the first limit.

[0068] In some embodiments, the carbon load is calculated based on the pressure difference across the particulate matter treatment device and the volumetric flow rate of the exhaust gas, wherein the volumetric flow rate of the exhaust gas is equal to the mass flow rate of the exhaust gas divided by the density of the exhaust gas.

[0069] In other embodiments, when the carbon load is greater than or equal to a first limit, the following measures can be taken to quickly reduce the carbon load: Measure 1: Increase the NOx setpoint (the value of the first preset NOx emission ratio) at the second temperature sensor (which collects the temperature at the outlet of the first NOx treatment device), increasing the total NOx amount, thus increasing the amount of NO2 generated in the particulate matter treatment device. Measure 2: Trigger thermal management based on the current average temperature and rate of change to increase the temperature. The average temperature is calculated by weighting the temperature at the outlet of the third temperature sensor (which collects the temperature at the outlet of the particulate matter treatment device) and the calculated downstream temperature of the second NOx treatment device. Using the outlet temperature and exhaust gas flow rate of the particulate matter treatment device as input, the downstream temperature is calculated based on the carrier heat capacity and energy conservation. The average temperature change rate is obtained by dividing the average temperature change over a fixed time by a fixed time period. When the average temperature is higher than the first preset temperature, the engine's intake valves and other mechanisms are used to increase the temperature. When the average temperature is within the range of the first and second preset temperatures, if the rate of change of the average temperature is less than or equal to the rate of change limit, the engine's intake valves and other mechanisms, as well as in-cylinder after-injection, are used to increase the temperature. If the rate of change of the average temperature is greater than the rate of change limit, the engine's intake valves and other mechanisms are used to increase the temperature. When the average temperature is lower than the second preset temperature, the engine's intake valves and other mechanisms, as well as in-cylinder after-injection, are used to increase the temperature.

[0070] In other embodiments, when the carbon load is greater than or equal to the second limit, a parking regeneration request is triggered, and engine thermal management and fuel injection regeneration are performed under stable operating conditions to raise the exhaust temperature to 550°C. After a certain period of time, the regeneration is completed, maintaining a high regeneration effect.

[0071] The following describes a vehicle comprising: an engine; an aftertreatment system as proposed in this application, the aftertreatment system being located downstream of the engine's exhaust outlet; and a controller, which is communicatively connected to the aftertreatment system and is used to control the aftertreatment system to execute the control method of the aftertreatment system proposed in this application.

[0072] Figure 3 This is a schematic diagram of the control structure of a post-processing system provided in an exemplary embodiment of this application, as shown below. Figure 3 As shown, the control device 3 of the aftertreatment system includes: a first calculation module 31, used to calculate the urea injection quantity of the first nitrogen oxide treatment device based on exhaust gas data, nitrogen oxide concentration at the inlet of the first nitrogen oxide treatment device, temperature before the inlet of the first nitrogen oxide treatment device, and space velocity of the first nitrogen oxide treatment device; a first adjustment module 32, used to adjust the urea injection quantity towards the first nitrogen oxide treatment device based on the nitrogen oxide concentration at the outlet of the first nitrogen oxide treatment device, temperature before the inlet of the first nitrogen oxide treatment device, and preset nitrogen oxide emission ratio; and a second calculation module 33, used to calculate the urea injection quantity based on the temperature before the inlet of the particulate matter treatment device. The first calculation module 34 is used to calculate the ratio of nitrogen dioxide and nitrogen oxides output by the particulate matter treatment device based on the nitrogen oxide concentration at the outlet of the first nitrogen oxide treatment device, the temperature at the inlet of the second nitrogen oxide treatment device, and the air velocity of the particulate matter treatment device; the second adjustment module 35 is used to adjust the amount of urea injected into the second nitrogen oxide treatment device based on the nitrogen oxide concentration at the outlet of the second nitrogen oxide treatment device and the second preset nitrogen oxide emission ratio.

[0073] The control device for the aftertreatment system provided in this application simultaneously reduces nitrogen oxides and oxidizes and removes ammonia by arranging a multifunctional catalyst in the first nitrogen oxide treatment unit and combining it with urea injected through a urea nozzle. In the particulate matter treatment unit, a multifunctional catalyst is arranged to capture particulate matter and catalyze the generation of nitrogen dioxide. In the second nitrogen oxide treatment unit, urea injected through a urea nozzle reduces nitrogen oxides and oxidizes and removes ammonia. Through the multifunctional catalyst design, the installation space for the aftertreatment system remains essentially unchanged. Furthermore, by monitoring temperature with a temperature sensor and monitoring the nitrogen oxide concentration at each stage with a nitrogen oxide sensor, the injection volume of the urea nozzle can be flexibly adjusted to prevent waste of reducing agent and reduce the possibility of secondary pollution caused by ammonia leakage after catalyst catalysis, thereby achieving lower emissions.

[0074] In one embodiment, the first calculation module 31 may be configured to: determine the nitrogen oxide conversion efficiency of the first nitrogen oxide treatment device based on the temperature before the air inlet of the first nitrogen oxide treatment device and the space velocity of the first nitrogen oxide treatment device; and calculate the urea injection quantity of the first nitrogen oxide treatment device based on the exhaust gas data, the nitrogen oxide concentration at the air inlet of the first nitrogen oxide treatment device and the nitrogen oxide conversion efficiency of the first nitrogen oxide treatment device.

[0075] In one embodiment, the first adjustment module 32 may be configured to: calculate the actual nitrogen oxide ratio emission of the first nitrogen oxide treatment device based on the nitrogen oxide concentration at the outlet of the first nitrogen oxide treatment device and the exhaust gas data; and when the actual nitrogen oxide ratio emission of the first nitrogen oxide treatment device exceeds the emission range of the first preset nitrogen oxide ratio emission, adjust the urea injection amount of the first nitrogen oxide treatment device based on the deviation between the actual nitrogen oxide ratio emission of the first nitrogen oxide treatment device and the first preset nitrogen oxide ratio emission.

[0076] In one embodiment, the second calculation module 33 may be configured to: obtain a weighted temperature value based on the temperature before the air inlet of the particulate matter treatment device and the temperature before the air inlet of the second nitrogen oxide treatment device; determine a preset ratio of nitrogen dioxide and nitrogen oxides based on the weighted temperature value and the air velocity of the particulate matter treatment device; and calculate the ratio of nitrogen dioxide and nitrogen oxides output by the particulate matter treatment device based on the nitrogen oxide concentration at the air outlet of the first nitrogen oxide treatment device and the preset ratio of nitrogen dioxide and nitrogen oxides.

[0077] In one embodiment, the second adjustment module 35 may be configured to: calculate the actual nitrogen oxide ratio emission of the second nitrogen oxide treatment device based on the nitrogen oxide concentration at the outlet of the second nitrogen oxide treatment device and the exhaust gas data; and adjust the urea injection amount of the second nitrogen oxide treatment device based on the deviation between the actual nitrogen oxide ratio emission of the second nitrogen oxide treatment device and the second preset nitrogen oxide ratio emission when the actual nitrogen oxide ratio emission of the second nitrogen oxide treatment device exceeds the emission range of the second preset nitrogen oxide ratio emission.

[0078] In one embodiment, the control device of the aftertreatment system may further be configured to: calculate the carbon load based on the first pressure difference of the particulate matter treatment device and the exhaust gas data; wherein the first pressure difference represents the differential pressure between the inlet and outlet of the particulate matter treatment device; adjust the urea injection quantity and temperature when the carbon load is greater than or equal to a first limit; and trigger a parking regeneration request when the carbon load is greater than or equal to a second limit; wherein the second limit is greater than the first limit.

[0079] The methods in this application can be implemented, in whole or in part, by software, hardware, firmware, or any combination thereof. When implemented in software, they can be implemented, in whole or in part, as a computer program product. This computer program product includes one or more computer programs or instructions that, when loaded and executed on a computer, perform, in whole or in part, the processes or functions described in this application. The computer can be a general-purpose computer, a special-purpose computer, a computer network, network equipment, user equipment, core network equipment, OAM (Operational Information Management), or other programmable devices.

[0080] The computer program product can be written in any combination of one or more programming languages ​​to perform the operations of the embodiments of this application. The programming languages ​​include object-oriented programming languages ​​such as Java and C++, as well as conventional procedural programming languages ​​such as C or similar languages. The program code can be executed entirely on the user's computing device, partially on the user's computing device, as a standalone 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.

[0081] The computer program or instructions may be stored in a computer-readable storage medium or transferred from one computer-readable storage medium to another. For example, the computer program or instructions may be transferred from one website, computer, server, or data center to another website, computer, server, or data center via wired or wireless means. The computer-readable storage medium may be any available medium that a computer can access, or a data storage device such as a server or data center that integrates one or more available media. The available medium may be a magnetic medium, such as a floppy disk, hard disk, or magnetic tape; or an optical medium, such as a digital video optical disc; or 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.

[0082] Furthermore, embodiments of this application may also be storage media storing a computer program, which is executed by a processor through steps of a control method for a post-processing system described in any of the above embodiments of this specification:

[0083] For the foregoing method embodiments, in order to simplify the description, they are all described as a series of actions. However, those skilled in the art should understand that this application is not limited to the described order of actions, because according to this application, some steps can be performed in other orders or simultaneously. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are all preferred embodiments, and the actions and modules involved are not necessarily essential to this application.

[0084] It should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For apparatus embodiments, since they are basically similar to method embodiments, the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments.

[0085] The steps in the methods of the various embodiments of this application can be adjusted, combined, or deleted according to actual needs, and the technical features described in each embodiment can be replaced or combined. The apparatuses in the various embodiments of this application can be combined, divided, or deleted according to actual needs.

[0086] Those skilled in the art will further recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software 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 beyond the scope of this application.

[0087] The steps of the methods or algorithms described in conjunction with the embodiments disclosed herein can be implemented directly by hardware, a software unit executed by a processor, or a combination of both. The software unit can be located in random access memory (RAM), main 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 known in the art.

[0088] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0089] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily 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 this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A control method for a post-processing system, characterized in that, The aftertreatment system includes: a first nitrogen oxide treatment device located downstream of the engine's exhaust outlet; a particulate matter treatment device located downstream of the first nitrogen oxide treatment device, the particulate matter treatment device being coated with a catalyst of an oxidation catalytic converter formulation and a catalyst of a particulate matter trap formulation; a second nitrogen oxide treatment device located downstream of the particulate matter treatment device; a urea nozzle for spraying urea into the first nitrogen oxide treatment device and the second nitrogen oxide treatment device; a temperature sensor for detecting the temperature before the intake of the first nitrogen oxide treatment device, the temperature before the intake of the particulate matter treatment device, and the temperature before the intake of the second nitrogen oxide treatment device; and a nitrogen oxide sensor for detecting the nitrogen oxide concentration at the intake of the first nitrogen oxide treatment device, the nitrogen oxide concentration at the outlet of the first nitrogen oxide treatment device, and the nitrogen oxide concentration at the outlet of the second nitrogen oxide treatment device. The control methods for the post-processing system include: Based on the exhaust gas data, the nitrogen oxide concentration at the inlet of the first nitrogen oxide treatment device, the temperature before the inlet of the first nitrogen oxide treatment device, and the space velocity of the first nitrogen oxide treatment device, calculate the urea injection quantity of the first nitrogen oxide treatment device. The nitrogen oxide conversion efficiency of the first nitrogen oxide treatment device is determined based on the temperature before the inlet of the first nitrogen oxide treatment device and the space velocity of the first nitrogen oxide treatment device. Based on the exhaust gas data, the nitrogen oxide concentration at the inlet of the first nitrogen oxide treatment device, and the nitrogen oxide conversion efficiency of the first nitrogen oxide treatment device, the urea injection rate of the first nitrogen oxide treatment device is calculated. The amount of urea injected into the first nitrogen oxide treatment device is adjusted based on the nitrogen oxide concentration at the outlet of the first nitrogen oxide treatment device, the temperature before the inlet of the first nitrogen oxide treatment device, and the preset nitrogen oxide emission ratio. Based on the nitrogen oxide concentration at the outlet of the first nitrogen oxide treatment device and the exhaust gas data, calculate the actual nitrogen oxide emission ratio of the first nitrogen oxide treatment device; When the actual nitrogen oxide ratio emission of the first nitrogen oxide treatment device exceeds the emission range of the first preset nitrogen oxide ratio emission, the urea injection amount of the first nitrogen oxide treatment device is adjusted based on the deviation between the actual nitrogen oxide ratio emission of the first nitrogen oxide treatment device and the first preset nitrogen oxide ratio emission. The ratio of nitrogen dioxide and nitrogen oxides output by the particulate matter treatment device is calculated based on the temperature before the air inlet of the particulate matter treatment device, the temperature before the air inlet of the second nitrogen oxide treatment device, and the air velocity of the particulate matter treatment device. A weighted temperature value is obtained based on the temperature at the inlet of the particulate matter treatment device and the temperature at the inlet of the second nitrogen oxide treatment device. The preset ratio of nitrogen dioxide and nitrogen oxides is determined based on the weighted temperature value and the air velocity of the particulate matter treatment device. Based on the nitrogen oxide concentration at the outlet of the first nitrogen oxide treatment device and the preset ratio of nitrogen dioxide and nitrogen oxides, the ratio of nitrogen dioxide and nitrogen oxides output by the particulate matter treatment device is calculated. The urea injection rate of the second nitrogen oxide treatment device is calculated based on the nitrogen oxide concentration at the outlet of the first nitrogen oxide treatment device, the temperature before the inlet of the second nitrogen oxide treatment device, and the ratio of nitrogen dioxide to nitrogen oxides output by the particulate matter treatment device. The amount of urea injected into the second nitrogen oxide treatment device is adjusted according to the nitrogen oxide concentration at the outlet of the second nitrogen oxide treatment device and the second preset nitrogen oxide emission ratio.

2. The control method for the post-processing system according to claim 1, characterized in that, Based on the nitrogen oxide concentration at the outlet of the second nitrogen oxide treatment device and the second preset nitrogen oxide emission ratio, the urea injection rate into the second nitrogen oxide treatment device is adjusted, including: Based on the nitrogen oxide concentration at the outlet of the second nitrogen oxide treatment device and the exhaust gas data, calculate the actual nitrogen oxide emission ratio of the second nitrogen oxide treatment device; When the actual nitrogen oxide ratio emission of the second nitrogen oxide treatment device exceeds the emission range of the second preset nitrogen oxide ratio emission, the urea injection amount of the second nitrogen oxide treatment device is adjusted based on the deviation between the actual nitrogen oxide ratio emission of the second nitrogen oxide treatment device and the second preset nitrogen oxide ratio emission.

3. The control method for the post-processing system according to claim 1, characterized in that, The control methods for post-processing systems also include: The carbon load is calculated based on the first pressure difference of the particulate matter treatment device and the exhaust gas data; wherein, the first pressure difference represents the pressure difference between the inlet and outlet of the particulate matter treatment device. When the carbon loading is greater than or equal to the first limit, the urea injection volume and temperature are adjusted. When the carbon load is greater than or equal to the second limit, a parking regeneration request is triggered; The second limit is greater than the first limit.

4. A vehicle, characterized in that, include: engine; An aftertreatment system located downstream of the engine's exhaust outlet; A controller, which is communicatively connected to the post-processing system, is used to control the post-processing system to perform the control method of the post-processing system as described in any one of claims 1-3.

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