A passive regeneration intensity control method based on carbon load and exhaust characteristics
Patent Information
- Application Number
- CN202610762240.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-07-10
- Publication Date
- 2026-08-04
Smart Images
Figure CN122504547A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of diesel engine exhaust aftertreatment technology, and in particular to a passive regeneration intensity control method based on carbon loading and exhaust characteristics. Background Technology
[0002] With the future formulation of China VII emission regulations, the emission limit for particulate matter number (PN) will be further tightened, from the current PN23 (particles larger than 23nm) to PN10 (particles larger than 10nm). This will result in a very small margin for PN emissions in real-world driving, especially in heavy-duty vehicles, and there is a risk of exceeding the standard in harsh PEMS (real-world emission testing).
[0003] Research has found that a significant reason for the surge in PN emissions under high-load conditions is the uncontrolled passive regeneration process of diesel particulate filters. Passive regeneration refers to the process in which, under certain temperature conditions (usually exceeding 300°C) and the presence of NO2, the carbon soot accumulated in the diesel particulate filter reacts with NO2 (C + 2NO2 → CO2 + 2NO) to generate gaseous products, thereby consuming the carbon soot. This process is originally beneficial, as it can reduce the carbon load of the diesel particulate filter without consuming additional fuel.
[0004] However, when there is a high concentration of NO2 upstream of the diesel particulate filter, it can trigger a strong passive regeneration reaction. This excessively strong passive regeneration can lead to the following problems: First, the intense carbon oxidation reaction can cause the carbon cake layer accumulated inside the diesel engine particulate filter to collapse locally, and the particulate matter that was originally captured by the carbon layer is released in a discrete manner, resulting in a surge in instantaneous particulate emissions. Secondly, in the areas where the carbon cake layer collapses, the local airflow resistance decreases due to the loss of the carbon layer's coverage and protection, causing a sharp increase in flow velocity in these areas. Consequently, the particulate filtration efficiency of the diesel engine particulate filter drops significantly, further exacerbating particulate leakage.
[0005] Currently, control strategies for diesel particulate filter regeneration mainly focus on the timing and temperature control of active regeneration (using post-injection fuel to increase temperature and burn off carbon soot), lacking effective intervention methods for passive regeneration. Traditional aftertreatment systems are often helpless in dealing with the problem of carbon cake layer collapse and leakage caused by passive regeneration. Although hardware optimization has laid the physical foundation for particulate emission control, actual road conditions are constantly changing, and control strategies still need to be dynamically adapted. Especially under high-load conditions, excessive passive regeneration can cause instantaneous damage to the carbon cake layer, and once collapse and leakage occur, traditional control systems cannot respond and intervene in time. Summary of the Invention
[0006] This invention provides a passive regeneration intensity control method based on carbon loading and exhaust characteristics to solve the problem that the existing technology lacks effective control means for the passive regeneration process of diesel engine particulate filters, and that excessive passive regeneration under high load conditions leads to carbon cake layer collapse, decreased particulate filtration efficiency, and excessive particulate emissions.
[0007] On one hand, the present invention provides a passive regeneration intensity control method based on carbon loading and exhaust characteristics, comprising: S1: Real-time monitoring of exhaust temperature, NO2 concentration and exhaust volume flow rate upstream of the diesel particulate filter, and real-time acquisition of the current carbon load of the diesel particulate filter through the carbon load model in the engine management system; S2: Passive regeneration intensity is calculated in real time based on the rate of decrease of carbon loading model values; S3: Establish a three-dimensional mapping model between passive regeneration intensity and exhaust temperature, NO2 concentration, and exhaust volume flow rate; S4: Obtain measured emission data of particulate matter in the tailpipe, calibrate the safety threshold of passive regeneration intensity under different exhaust volume flow rates, and obtain a table showing the variation with flow rate. S5: During engine operation, the current passive regeneration intensity is calculated in real time, and the dynamic safety threshold is obtained by looking up the table based on the current exhaust volume flow rate. S6: When the passive regeneration intensity is greater than the dynamic safety threshold and the current carbon load of the diesel engine particulate filter is higher than the set lower limit of carbon load, the engine combustion parameters are actively adjusted to suppress NO2 generation until the passive regeneration intensity falls back to the safe range and then the suppression mode is exited.
[0008] Furthermore, S1: Real-time monitoring of exhaust temperature, NO2 concentration, and exhaust volumetric flow rate upstream of the diesel particulate filter, and real-time acquisition of the current carbon load of the diesel particulate filter through the carbon load model in the engine management system, including: S11: Real-time monitoring of exhaust temperature via a high-precision temperature sensor positioned upstream of the diesel particulate filter; S12: The NO2 concentration upstream of the diesel engine particulate filter is estimated using an NO2 sensor combined with a model; S13: The exhaust volume flow rate is obtained by converting data from the intake flow sensor and the exhaust temperature sensor. S14: The sensor data mentioned above is transmitted to the carbon load model in the engine management system in real time, and the current carbon load of the diesel particulate filter is obtained in real time.
[0009] Furthermore, S2: The passive regeneration intensity is calculated in real time based on the rate of decrease of the carbon loading model value, including: S21: Based on the carbon loading model, record the reduction in carbon loading and the duration of the time window within a continuous time window. S22: Based on the reduction in carbon loading within the time window and the duration of the time window, the passive regeneration intensity is calculated according to PRIcur=ΔM / Δt, where PRIcur is the passive regeneration intensity, ΔM is the reduction in carbon loading within the time window, and Δt is the duration of the time window. S23: Filter the calculated passive regeneration intensity to eliminate data fluctuations and obtain a smooth real-time value of the passive regeneration intensity.
[0010] Furthermore, S3: Establish a three-dimensional mapping model between passive regeneration intensity and exhaust temperature, NO2 concentration, and exhaust volumetric flow rate, including: S31: Based on engine bench tests, real-time data is collected on exhaust temperature, NO2 concentration, exhaust volume flow rate and corresponding real-time passive regeneration intensity under different steady-state operating conditions. S32: Build a 3D mapping model using real-time acquired data and update the mapping model regularly.
[0011] Further, S4: Obtain measured emission data of particulate matter quantity in the tailrace, calibrate the safety threshold of passive regeneration intensity under different exhaust volume flow rates, and obtain a table showing the variation with flow rate, including: S41: On the engine test bench, the engine load is gradually increased for different exhaust volume flow rates, and the number concentration of exhaust particulate matter is monitored in real time. S42: Record the passive regeneration intensity corresponding to the data point before the number of particulate matter emissions in the tail section begins to increase significantly, that is, obtain the corresponding critical intensity; S43: Obtain and record the critical intensity corresponding to each flow point to obtain the relationship between passive regeneration intensity and flow rate; S44: Take the critical intensity at each flow rate, multiply it by the safety factor, obtain the safety threshold at that flow rate, and create a table showing how it changes with the flow rate; Furthermore, S5: During engine operation, the current passive regeneration intensity is calculated in real time, and a dynamic safety threshold is obtained by looking up a table based on the current exhaust volume flow rate, including: S51: During engine operation, the engine management system calculates the current passive regeneration intensity and the current exhaust volume flow rate in real time; S52: Based on the current exhaust volume flow rate and the table showing how the flow rate changes, obtain the dynamic safety threshold.
[0012] Furthermore, S6: When the passive regeneration intensity exceeds the dynamic safety threshold and the current carbon load of the diesel engine particulate filter is higher than the set lower limit of carbon load, the engine combustion parameters are actively adjusted to suppress NO2 generation until the passive regeneration intensity falls back to a safe range, at which point the suppression mode is exited, including: S61: The engine management system compares the calculated passive regeneration intensity with the dynamic safety threshold obtained by looking up the table in real time. When the passive regeneration intensity is greater than the dynamic safety threshold and the current carbon load of the diesel particulate filter is higher than the set lower limit of carbon load, the engine management system determines that it has entered the excessive passive regeneration state. S62: The engine management system actively adjusts engine combustion parameters to reduce NO2 concentration in order to reduce the intensity of passive regeneration reaction. S63: The adjustment measures include adjusting one or more combinations of exhaust gas recirculation rate, injection timing, injection pressure, intake throttle valve, and VGT opening; S64: The adjustment range adopts a closed-loop control strategy to continuously monitor the adjustment effect.
[0013] Furthermore, adjusting the exhaust gas recirculation rate includes: Increase the amount of exhaust gas recirculation, reduce the oxygen concentration and combustion temperature in the combustion chamber, and inhibit NO2 formation; The range of exhaust gas recirculation rate is set according to engine operating conditions and emission requirements; The exhaust gas recirculation valve is controlled by electric or pneumatic means. During the adjustment of the exhaust gas recirculation rate, the changes in exhaust temperature and oxygen concentration are monitored.
[0014] Furthermore, adjusting the injection timing includes: Delaying the injection timing lowers the peak combustion temperature and reduces NO2 formation; The range of fuel injection timing is set according to engine speed and load; The injectors employ high-pressure common rail or electronically controlled unit pump technology, and during the injection timing adjustment process, the engine's power and fuel economy are monitored.
[0015] Furthermore, closed-loop control strategies include: Continuously monitor the rate of change of NO2 concentration and carbon loading after adjustment, and recalculate the real-time passive regeneration intensity; The recalculated passive regeneration intensity is compared with the dynamic safety threshold to determine whether further adjustment is needed. Once the passive regeneration intensity drops back to a safe range and remains there for a certain period of time, the system determines that the risk to the carbon cake layer has been eliminated. The engine combustion parameters are gradually restored to normal, and the passive regeneration suppression mode is smoothly exited.
[0016] The beneficial effects of the passive regeneration intensity control method based on carbon loading and exhaust characteristics provided by this invention are as follows: This invention proposes for the first time a method for real-time calculation of passive regeneration intensity based on a carbon load model to reduce the rate of regeneration. It utilizes existing ECU resources, requires no additional hardware costs, has clear physical meaning, and good real-time performance. By using a threshold calibration method based on actual measured emissions of particulate matter from exhaust, the point preceding the point of sudden increase in the number of exhaust particles is taken as the critical intensity. The threshold setting is linked to the direct consequences of carbon cake layer collapse, ensuring the effectiveness and specificity of the control. At the same time, the threshold is dynamically adjusted with exhaust flow rate to adapt to the differences in carbon cake layer stability under different operating conditions. A three-dimensional mapping model of passive regeneration intensity with exhaust temperature, NO2 concentration, and exhaust flow rate is established, which can be used for feedforward control and offline optimization. Carbon loading is used as an independent condition for triggering the suppression mode rather than as a model input, making the logic clearer. Under high-load conditions, the intervention focuses on reducing NO2 concentration, which avoids the power loss and slow control response caused by forcibly reducing exhaust temperature, and is more in line with the actual operating characteristics of the engine. It effectively reduces the risk of excessive particulate matter emissions in actual road PEMS testing, and provides a guarantee for the emission compliance of heavy-duty vehicles under harsh operating conditions; The closed-loop control strategy ensures the accuracy and safety of intervention, avoiding over-adjustment that could affect engine economy and drivability. Attached Figure Description
[0017] To more clearly illustrate the technical solutions in this invention 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 some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.
[0018] Figure 1 This is a schematic flowchart of the passive regeneration intensity control method based on carbon loading and exhaust characteristics provided in an embodiment of the present invention. Figure 2 This is a schematic diagram illustrating the mapping relationship between passive regeneration intensity and NO2 concentration, temperature, and exhaust flow rate of the passive regeneration intensity control method based on carbon loading and exhaust characteristics provided in this embodiment of the invention. Figure 3 This is a schematic diagram of the passive regeneration intensity threshold calibration method of the passive regeneration intensity control method based on carbon loading and exhaust characteristics provided in the embodiments of the present invention; Figure 4 This is a passive regeneration suppression control logic diagram under high load conditions for the passive regeneration intensity control method based on carbon loading and exhaust characteristics provided in the embodiments of the present invention. Detailed Implementation
[0019] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.
[0020] Figure 1 This is one of the flowcharts of the passive regeneration intensity control method based on carbon loading and exhaust characteristics provided in the embodiments of the present invention.
[0021] like Figures 1 to 4 As shown in the embodiment of the present invention, the passive regeneration intensity control method based on carbon loading and exhaust characteristics mainly includes the following steps: S1: Real-time monitoring of exhaust temperature, NO2 concentration and exhaust volume flow rate upstream of the diesel particulate filter, and real-time acquisition of the current carbon load of the diesel particulate filter through the carbon load model in the engine management system (ECU); S2: Passive regeneration intensity is calculated in real time based on the rate of decrease of carbon loading model values; S3: Establish a three-dimensional mapping model between passive regeneration intensity and exhaust temperature, NO2 concentration, and exhaust volume flow rate; S4: Obtain measured emission data of particulate matter in the tailpipe, calibrate the safety threshold of passive regeneration intensity under different exhaust volume flow rates, and obtain a table showing the variation with flow rate. S5: During engine operation, the current passive regeneration intensity is calculated in real time, and the dynamic safety threshold is obtained by looking up the table based on the current exhaust volume flow rate. S6: When the passive regeneration intensity is greater than the dynamic safety threshold and the current carbon load of the diesel engine particulate filter is higher than the set lower limit of carbon load, the engine combustion parameters are actively adjusted to suppress NO2 generation until the passive regeneration intensity falls back to the safe range and then the suppression mode is exited.
[0022] In this embodiment of the invention, the passive regeneration intensity is calculated in real time by monitoring the upstream state parameters and carbon load change rate of the DPF. A mapping model between the passive regeneration intensity and exhaust flow rate, temperature, and NO2 concentration is established to accurately grasp the intensity change during the passive regeneration process of the DPF. Under different exhaust flow rates, the corresponding PRI safety threshold is calibrated based on the PN exhaust spike point to ensure the scientific nature and relevance of the safety threshold. Under high-load conditions, when the calculated passive regeneration intensity exceeds the safety threshold under the current flow rate and the carbon load is higher than the set value, the engine combustion parameters are actively adjusted to suppress NO2 generation, thereby weakening the passive regeneration reaction intensity and protecting the integrity of the carbon cake structure. A closed-loop control strategy is adopted to continuously monitor and adjust until the passive regeneration intensity falls back to the safe range and then exits the suppression mode. This effectively reduces the risk of PN emissions exceeding the standard under high-load conditions and provides strong protection for the emission compliance of heavy-duty vehicles under harsh conditions. Here, DPF is the diesel particulate filter, ECU is the engine management system, and PN is the exhaust particulate matter quantity. like Figures 1 to 4 As shown, S1: Real-time monitoring of exhaust temperature, NO2 concentration, and exhaust volumetric flow rate upstream of the diesel particulate filter, and real-time acquisition of the current carbon load of the diesel particulate filter through the carbon load model in the engine management system, including: S11: Real-time monitoring of exhaust temperature via a high-precision temperature sensor positioned upstream of the diesel particulate filter; S12: The NO2 concentration upstream of the diesel engine particulate filter is estimated using an NO2 sensor combined with a model; S13: The exhaust volume flow rate is obtained by converting data from the intake flow sensor and the exhaust temperature sensor. S14: The sensor data mentioned above is transmitted to the carbon load model in the engine management system in real time, and the current carbon load of the diesel particulate filter is obtained in real time.
[0023] In this embodiment of the invention, the exhaust temperature (T, unit: °C) upstream of the DPF is monitored in real time by a high-precision temperature sensor, which can accurately grasp the thermal state of the exhaust system. This data is crucial for assessing the oxidation reaction conditions of soot inside the DPF, because the passive regeneration process needs to be carried out within a certain temperature range (usually exceeding 300 °C). Real-time temperature monitoring helps to determine whether the current operating conditions meet the conditions for passive regeneration and provides basic data for subsequent control strategies. Secondly, by using an NO2 sensor combined with a model to estimate the NO2 concentration (CNO2, unit: ppm) upstream of the DPF, the concentration of the key oxidant in the passive regeneration reaction can be accurately obtained. NO2 is the main oxidant in the passive regeneration process of DPF, and its concentration directly affects the oxidation rate of soot. By monitoring the NO2 concentration in real time, the intensity of passive regeneration can be accurately assessed, and measures can be taken in time to suppress excessive regeneration when the concentration is too high, so as to prevent the collapse of the soot layer and the surge in particulate matter emissions. Furthermore, the exhaust volume flow rate (Q, unit: m³) is obtained by converting data from the intake flow sensor and exhaust temperature sensor. 3 The system can provide a comprehensive understanding of the flow state of the exhaust system. The exhaust volume flow rate is one of the important factors affecting the passive regeneration intensity. An increase in flow rate will exacerbate the shear force on the carbon cake layer and increase the risk of collapse. Real-time monitoring of the exhaust volume flow rate helps to assess the stability of the carbon cake layer under the current operating conditions and provides a basis for the dynamic correction of the safety threshold. Finally, the aforementioned sensor data is transmitted in real time to the carbon load model in the engine management system (ECU), and the current carbon load of the DPF (M, unit: g / L) is obtained in real time. Carbon load is an important indicator for evaluating the working status and regeneration needs of the DPF. By monitoring changes in carbon load in real time, it is possible to determine whether the DPF needs active or passive regeneration, and to dynamically adjust the control strategy during the regeneration process to ensure the safety and effectiveness of the regeneration process. At the same time, carbon load data is also an important basis for calculating the intensity of passive regeneration and the safety threshold.
[0024] like Figures 1 to 4 As shown, S2: The passive regeneration intensity is calculated in real time based on the rate of decrease of the carbon loading model value, including: S21: Based on the carbon loading model, record the reduction in carbon loading and the duration of the time window within a continuous time window. S22: Based on the reduction in carbon loading within the time window and the duration of the time window, the passive regeneration intensity is calculated according to PRIcur=ΔM / Δt, where PRIcur is the passive regeneration intensity, ΔM is the reduction in carbon loading within the time window, and Δt is the duration of the time window. S23: Filter the calculated passive regeneration intensity to eliminate data fluctuations and obtain a smooth real-time value of the passive regeneration intensity.
[0025] In this embodiment of the invention, within a continuous time window (e.g., every 5 seconds is a calculation cycle, and the window length can be adjusted according to actual needs), the change ΔM of the carbon loading model value is recorded, and the duration Δt of the time window is also recorded. Then, the average passive regeneration intensity PRIcur within the current time window is calculated as follows: PRIcur=ΔM / Δt Where ΔM is the reduction in carbon load within the time window (in g / L), Δt is the duration of the time window (in h), and PRIcur is the passive regeneration intensity (in g / L / h). Considering that there may be large instantaneous fluctuations in the carbon load model, the calculated PRIcur can be filtered to obtain a smooth real-time value of the passive regeneration intensity. This method utilizes the existing carbon load model resources in the ECU, without the need to add additional sensors, and directly reflects the actual intensity of passive regeneration through the rate of carbon load decrease. It has the advantages of good real-time performance and clear physical meaning.
[0026] like Figures 1 to 4 As shown, S3: Establish a three-dimensional mapping model between passive regeneration intensity and exhaust temperature, NO2 concentration, and exhaust volumetric flow rate, including: S31: Based on engine bench tests, real-time data is collected on exhaust temperature, NO2 concentration, exhaust volume flow rate and corresponding real-time passive regeneration intensity under different steady-state operating conditions. S32: Build a 3D mapping model using real-time acquired data and update the mapping model regularly.
[0027] In this embodiment of the invention, based on engine bench tests, data under different steady-state operating conditions are collected, including exhaust temperature T, NO2 concentration CNO2, exhaust volumetric flow rate Q, and the corresponding passive regeneration intensity PRIcur. A three-dimensional mapping model is then established using the above data. PRIcur = f(T, CNO2, Q) Wherein, PRIcur represents the passive regeneration intensity, T represents the exhaust temperature, CNO2 represents the NO2 concentration, and Q represents the exhaust volumetric flow rate. This three-dimensional mapping model can be in the form of a lookup table (calibrated according to the three dimensions of temperature, NO2 concentration, and flow rate) or an empirical formula. The purpose of this three-dimensional mapping model is: in actual control, when it is necessary to quickly predict the risk of passive regeneration, the expected intensity can be obtained directly from the table based on the current operating parameters, serving as the basis for feedforward control. It should be noted that the carbon loading M does not directly participate in the mapping model of PRIcur, because the carbon loading has already been directly reflected in the calculation result of PRIcur through ΔM / Δt in step 1, so it does not need to be used as an input variable again. The carbon loading will be used as an independent condition for triggering the suppression mode.
[0028] like Figures 1 to 4 As shown, S4: Obtain measured emission data of particulate matter quantity in the tailrace, calibrate the safety threshold of passive regeneration intensity under different exhaust volume flow rates, and obtain a table showing the variation with flow rate, including: S41: On the engine test bench, the engine load is gradually increased for different exhaust volume flow rates, and the number concentration of exhaust particulate matter is monitored in real time. S42: Record the passive regeneration intensity corresponding to the data point before the number of particulate matter emissions in the tail section begins to increase significantly, that is, obtain the corresponding critical intensity; S43: Obtain and record the critical intensity corresponding to each flow point to obtain the relationship between passive regeneration intensity and flow rate; S44: Take the critical intensity at each flow rate, multiply it by the safety factor, obtain the safety threshold at that flow rate, and create a table showing how it changes with the flow rate; In this embodiment of the invention, on an engine test bench, different exhaust volume flow rates Q (e.g., 300, 500, 800, 1200 m³) are tested. 3 / h), perform the following operations respectively: With a fixed flow rate, the engine load is gradually increased (raising the temperature and NO2 concentration), while the exhaust PN concentration is monitored in real time. Record the data point before the PN emission begins to rise significantly (i.e., the carbon cake layer begins to collapse and leak), and determine the passive regeneration intensity PRIcur (obtained in real time by the method in step 1) at that moment as the critical intensity PRIcritical(Q) at that flow rate; Repeat the above process for each flow point to obtain the relationship between PRIcritical and flow rate; Multiply the critical intensity at each flow rate by a safety factor (e.g., 0.8) to obtain the safety threshold at that flow rate: PRImax(Q) = k × PRIcritical(Q) Where Q is the exhaust flow rate, PRImax(Q) is the safety threshold at flow rate Q, PRIcritical(Q) is the critical intensity at flow rate Q, and k is the safety factor (0 < k < 1, typical value can be 0.7~0.9). Finally, the calibration results are organized into a table with exhaust flow rate Q as the independent variable and stored in the ECU. During actual operation, the ECU looks up the table based on the current exhaust flow rate to obtain the dynamic PRImax(Q). An increase in PN emissions is a direct consequence of carbon cake collapse. Using the point before the PN spike as a threshold ensures that the carbon cake will not be damaged before PRI reaches a critical value. At the same time, the higher the flow rate, the greater the shear force on the carbon cake and the lower the allowable PRImax(Q), thus requiring flow rate correction.
[0029] like Figures 1 to 4 As shown, S5: During engine operation, the current passive regeneration intensity is calculated in real time, and the dynamic safety threshold is obtained by looking up a table based on the current exhaust volume flow rate, including: S51: During engine operation, the engine management system calculates the current passive regeneration intensity and the current exhaust volume flow rate in real time; S52: Based on the current exhaust volume flow rate and the table showing how the flow rate changes, obtain the dynamic safety threshold.
[0030] In this embodiment of the invention, during engine operation, the ECU performs the following judgment in real time: calculates the current passive regeneration intensity PRIcur using the method in step 1, and obtains the dynamic safety threshold PRImax(Q) by looking up a table based on the current exhaust flow rate Q; By calculating the passive regeneration intensity in real time and dynamically matching the safety threshold, precise control of the DPF passive regeneration process can be achieved, avoiding carbon cake collapse and excessive particulate matter emissions caused by excessive regeneration, while ensuring stable engine operation and emission compliance under high load conditions. The corresponding PRImax(Q) is obtained by looking up the table based on the current Q value, so that the safety threshold can be dynamically adjusted according to the operating conditions. The larger the flow rate, the stronger the shear force on the carbon cake layer, and the lower the PRImax(Q), thereby avoiding control failure caused by flow rate changes. The scientific and targeted nature of the threshold setting is ensured by the table (Q-PRImax(Q) relationship) calibrated by PN emission measurement, which is directly related to the critical condition of carbon cake layer collapse (a point before PN surge). The dynamic safety threshold provides the ECU with a basis for feedforward control, enabling the system to anticipate regeneration risks and take intervention measures (such as adjusting combustion parameters). By comparing the dynamic safety threshold with the real-time calculated PRIcur, a closed-loop control logic is formed to ensure the accuracy and timeliness of the intervention and avoid over-adjustment that could affect engine performance.
[0031] like Figures 1 to 4 As shown, S6: When the passive regeneration intensity is greater than the dynamic safety threshold and the current carbon load of the diesel engine particulate filter is higher than the set lower limit of carbon load, the engine combustion parameters are actively adjusted to suppress NO2 generation until the passive regeneration intensity falls back to the safe range, at which point the suppression mode is exited, including: S61: The engine management system compares the calculated passive regeneration intensity with the dynamic safety threshold obtained by looking up the table in real time. When the passive regeneration intensity is greater than the dynamic safety threshold and the current carbon load of the diesel particulate filter is higher than the set lower limit of carbon load, the engine management system determines that it has entered the excessive passive regeneration state. S62: The engine management system actively adjusts engine combustion parameters to reduce NO2 concentration in order to reduce the intensity of passive regeneration reaction. S63: The adjustment measures include adjusting one or more combinations of exhaust gas recirculation rate, injection timing, injection pressure, intake throttle valve, and VGT opening; S64: The adjustment range adopts a closed-loop control strategy to continuously monitor the adjustment effect.
[0032] In this embodiment of the invention, when PRIcur>PRImax(Q) (passive regeneration intensity exceeds the safety threshold under the current flow rate); M>Mmin (The carbon loading is higher than the set lower limit, which is generally set to 1.5g / L. At this point, a complete carbon cake layer is basically formed, avoiding false triggering when the carbon loading is extremely low). When both of the above conditions are met, the system determines that it has entered an overly strong passive regeneration state, which poses a risk of carbon cake layer collapse, and immediately triggers the passive regeneration suppression mode. After entering the suppression mode, the ECU actively adjusts the engine combustion parameters with the core objective of reducing NO2 concentration, thereby weakening the intensity of the passive regeneration reaction. The reason for focusing on reducing NO2 is that under high load conditions, the exhaust temperature is inherently high and strongly correlated with the engine load. Forcibly reducing the exhaust temperature will affect power output and result in a slow response. On the other hand, the amount of NO2 generated can be effectively controlled through combustion regulation, and NO2 is the main oxidant in passive regeneration. Reducing the NO2 concentration can directly suppress the passive regeneration reaction rate. The regulatory measures include one or more of the following combinations: Adjusting the EGR rate increases the amount of exhaust gas recirculation, reduces the oxygen concentration and combustion temperature in the combustion chamber, and directly inhibits NO2 formation. Adjusting the injection timing: Appropriately delaying injection reduces peak combustion temperature and decreases NO2 formation; Adjusting the injection pressure: Appropriately adjusting the injection pressure changes the combustion rate and affects NO2 formation; Adjust the intake throttle valve: In conjunction with the EGR system, optimize the in-cylinder oxygen concentration and suppress NO2 formation; Adjusting the opening of the variable geometry turbocharger (VGT): changes the boost pressure and intake volume, indirectly affecting the in-cylinder combustion environment and NO2 formation.
[0033] The adjustment range adopts a closed-loop control strategy: continuously monitor the rate of change of NO2 concentration and carbon loading after adjustment, recalculate the real-time passive regeneration intensity PRIcur until PRIcur falls back to the safe range (PRIcur≤PRImax(Q)). Exiting the suppression mode: When the passive regeneration intensity PRIcur falls back to a safe range (i.e., ≤PRImax(Q)) and remains there for a certain period of time (e.g., 30 seconds, which can be calibrated), the system determines that the risk of carbon cake layer has been eliminated, gradually restores the engine combustion parameters to normal, and smoothly exits the passive regeneration suppression mode.
[0034] like Figures 1 to 4 As shown, adjusting the exhaust gas recirculation rate includes: Increase the amount of exhaust gas recirculation, reduce the oxygen concentration and combustion temperature in the combustion chamber, and inhibit NO2 formation; The range of exhaust gas recirculation rate is set according to engine operating conditions and emission requirements; The exhaust gas recirculation valve is controlled by electric or pneumatic means. During the adjustment of the exhaust gas recirculation rate, the changes in exhaust temperature and oxygen concentration are monitored.
[0035] In this embodiment of the invention, NO2 generation is suppressed by increasing the amount of exhaust gas recirculation, which reintroduces some exhaust gas into the intake system, thereby reducing the oxygen concentration and combustion temperature in the combustion chamber. Since NO2 generation is highly dependent on high temperature and oxygen-rich environment, increasing the EGR rate can directly reduce the amount of NO2 generated, thereby weakening the intensity of the passive regeneration reaction of DPF (C + 2NO2 → CO2 + 2NO), and preventing the carbon cake layer from collapsing due to excessive oxidation. The EGR rate adjustment range is dynamically set according to engine load, speed and emission requirements; for example, under high load conditions, the EGR rate is appropriately increased to suppress NO2 formation; under low load or cold start conditions, the EGR rate is reduced to ensure combustion stability and power output; this dynamic adaptation ensures the flexibility and effectiveness of the control strategy. During EGR rate adjustment, exhaust temperature and oxygen concentration changes are monitored in real time by exhaust temperature and oxygen sensors. If the monitored values deviate from the expected range, the ECU can adjust the EGR valve opening (electric or pneumatic control) in a timely manner to form a closed-loop control circuit. This mechanism avoids combustion deterioration or NO2 suppression failure caused by excessive or insufficient EGR rate adjustment. EGR rate adjustment is often coordinated with parameters such as injection timing, injection pressure, and intake throttle valve. For example, when a significant reduction in NO2 is required, the injection timing can be delayed to reduce the peak combustion temperature, forming a multi-dimensional intervention and further improving the control effect on passive regeneration intensity.
[0036] like Figures 1 to 4 As shown, adjusting the fuel injection timing includes: Delaying the injection timing lowers the peak combustion temperature and reduces NO2 formation; The range of fuel injection timing is set according to engine speed and load; The injectors employ high-pressure common rail or electronically controlled unit pump technology, and during the injection timing adjustment process, the engine's power and fuel economy are monitored.
[0037] In this embodiment of the invention, by delaying the injection time, the fuel is injected into the cylinder in the later stage of the compression stroke, shortening the contact time between the fuel and the high-temperature compressed air, thereby reducing the peak combustion temperature. Since the NO2 generation rate is significantly accelerated under high temperature conditions, reducing the combustion temperature can effectively reduce the amount of NO2 generated, thereby weakening the intensity of the passive regeneration reaction of the DPF and preventing the carbon cake layer from collapsing due to excessive oxidation. The injection timing adjustment range is dynamically set according to engine speed and load; for example, under high load conditions, the injection timing is appropriately delayed to suppress NO2 generation; under low load or idling speed, it is restored to the normal injection timing to ensure combustion stability and fuel economy; this dynamic adaptation ensures the effectiveness of the control strategy under different operating conditions. The fuel injector uses high-pressure common rail or electronically controlled unit pump technology, which can precisely control the injection timing and injection quantity. During the adjustment of the injection timing, the high-pressure common rail system pressurizes the fuel through the high-pressure fuel pump and stores it in the common rail. Then, the ECU controls the fuel injector to inject fuel at a specific time, ensuring the accuracy of the injection timing adjustment and the response speed. During the fuel injection timing adjustment process, the engine power and fuel economy changes are monitored in real time by the engine speed sensor, torque sensor and other sensors. If a decrease in power or an increase in fuel consumption is detected, the ECU can adjust the fuel injection timing in a timely manner or coordinate with other parameters (such as fuel injection pressure, intake throttle valve opening, etc.) to form a closed-loop control circuit, ensuring that the engine maintains optimal power and fuel economy while suppressing NO2 generation.
[0038] like Figures 1 to 4 As shown, the closed-loop control strategy includes: Continuously monitor the rate of change of NO2 concentration and carbon loading after adjustment, and recalculate the real-time passive regeneration intensity; The recalculated passive regeneration intensity is compared with the dynamic safety threshold to determine whether further adjustment is needed. Once the passive regeneration intensity drops back to a safe range and remains there for a certain period of time, the system determines that the risk to the carbon cake layer has been eliminated. The engine combustion parameters are gradually restored to normal, and the passive regeneration suppression mode is smoothly exited.
[0039] In this embodiment of the invention, delaying the injection timing allows fuel to be injected into the cylinder later in the compression stroke, shortening the premixed combustion stage and reducing the formation of local high-temperature regions in the combustion chamber. Since the NO2 generation rate increases exponentially above 1300°C, this strategy can significantly reduce the amount of NO2 generated in a high-temperature, oxygen-rich environment, weakening the passive regeneration intensity of the DPF from the source (reaction formula: C + 2NO2 → CO2 + 2NO). By adjusting the injection timing to change the combustion phase, the generation of soot and the oxidation process are separated. Later injection increases the content of unburned hydrocarbons (UHC), promoting the HC-SCR reaction in the after-combustion treatment stage, further consuming NO2, and forming a dual inhibition effect. Speed-load MAP calibration: A three-dimensional injection timing adjustment matrix is established based on engine speed (N) and load (BMEP), for example: High speed and high load (N>2500rpm, BMEP>1.2MPa): Delay injection by 5-8°CA (crankshaft angle) to enhance NO2 suppression; Medium and low load conditions: Maintain original factory calibration or fine-tune 2-3°CA to avoid power loss; Transient compensation control: During acceleration / deceleration, adjust injection timing in advance through feedforward control to prevent a sudden increase in passive regeneration intensity caused by sudden changes in NO2 concentration. Employing a high-pressure common rail system (pressure ≥250MPa) or electronically controlled unit pump technology, the injection timing can be precisely adjusted in units of 0.1°CA, with a response time of <10ms, meeting real-time control requirements. Combining multi-stage injection technology of pre-injection + main injection + post-injection, by optimizing the injection ratio and interval angle of each stage, the peak temperature of the main combustion is reduced while ensuring complete combustion, thus reducing soot and CO emissions. When the ECU detects a decrease in power exceeding 3% or an increase in fuel consumption exceeding 5%, it automatically triggers a correction algorithm to optimize the combustion process while maintaining NO2 suppression by coordinating the adjustment of parameters such as EGR rate and intake throttle valve opening. In conjunction with the EGR system: Delayed injection timing and increased EGR rate create a complementary effect. For example, under high-load conditions, simultaneously increasing the EGR rate by 10% and delaying CA injection by 5° can reduce NO2 formation by more than 40%, while avoiding combustion delay caused by excessively high EGR rates. During passive regeneration suppression, adjusting the injection timing optimizes the exhaust temperature, maintaining it within the DPF active regeneration window (550-650°C), creating conditions for subsequent active regeneration and reducing the risk of carbon load accumulation. Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims
1. A passive regeneration intensity control method based on carbon loading and exhaust characteristics, characterized in that, include: S1: Real-time monitoring of exhaust temperature, NO2 concentration and exhaust volume flow rate upstream of the diesel particulate filter, and real-time acquisition of the current carbon load of the diesel particulate filter through the carbon load model in the engine management system; S2: Passive regeneration intensity is calculated in real time based on the rate of decrease of carbon loading model values; S3: Establish a three-dimensional mapping model between passive regeneration intensity and exhaust temperature, NO2 concentration, and exhaust volume flow rate; S4: Obtain measured emission data of particulate matter in the tailpipe, calibrate the safety threshold of passive regeneration intensity under different exhaust volume flow rates, and obtain a table showing the variation with flow rate. S5: During engine operation, the current passive regeneration intensity is calculated in real time, and the dynamic safety threshold is obtained by looking up the table based on the current exhaust volume flow rate. S6: When the passive regeneration intensity is greater than the dynamic safety threshold and the current carbon load of the diesel engine particulate filter is higher than the set lower limit of carbon load, the engine combustion parameters are actively adjusted to suppress NO2 generation until the passive regeneration intensity falls back to the safe range and then the suppression mode is exited.
2. The passive regeneration intensity control method based on carbon loading and exhaust characteristics according to claim 1, characterized in that, S1: Real-time monitoring of exhaust temperature, NO2 concentration, and exhaust volumetric flow rate upstream of the diesel engine particulate filter, and real-time acquisition of the current carbon load of the diesel engine particulate filter through the carbon load model in the engine management system, including: S11: Real-time monitoring of exhaust temperature via a high-precision temperature sensor positioned upstream of the diesel particulate filter; S12: The NO2 concentration upstream of the diesel engine particulate filter is estimated using an NO2 sensor combined with a model; S13: The exhaust volume flow rate is obtained by converting data from the intake flow sensor and the exhaust temperature sensor. S14: The sensor data mentioned above is transmitted to the carbon load model in the engine management system in real time, and the current carbon load of the diesel particulate filter is obtained in real time.
3. The passive regeneration intensity control method based on carbon loading and exhaust characteristics according to claim 2, characterized in that, S2: The passive regeneration intensity is calculated in real time based on the rate of decrease of the carbon loading model value, including: S21: Based on the carbon loading model, record the reduction in carbon loading and the duration of the time window within a continuous time window. S22: Based on the reduction in carbon loading within the time window and the duration of the time window, the passive regeneration intensity is calculated according to PRIcur=ΔM / Δt, where PRIcur is the passive regeneration intensity, ΔM is the reduction in carbon loading within the time window, and Δt is the duration of the time window. S23: Filter the calculated passive regeneration intensity to eliminate data fluctuations and obtain a smooth real-time value of the passive regeneration intensity.
4. The passive regeneration intensity control method based on carbon loading and exhaust characteristics according to claim 3, characterized in that, S3: Establish a three-dimensional mapping model between passive regeneration intensity and exhaust temperature, NO2 concentration, and exhaust volumetric flow rate, including: S31: Based on engine bench tests, real-time data is collected on exhaust temperature, NO2 concentration, exhaust volume flow rate and corresponding real-time passive regeneration intensity under different steady-state operating conditions. S32: Build a 3D mapping model using real-time acquired data and update the mapping model regularly.
5. The passive regeneration intensity control method based on carbon loading and exhaust characteristics according to claim 4, characterized in that, S4: Obtain measured emission data of particulate matter quantity in the tailrace, calibrate the safety threshold of passive regeneration intensity under different exhaust volume flow rates, and obtain a table showing the variation with flow rate, including: S41: On the engine test bench, the engine load is gradually increased for different exhaust volume flow rates, and the number concentration of exhaust particulate matter is monitored in real time. S42: Record the passive regeneration intensity corresponding to the data point before the number of particulate matter emissions in the tail section begins to increase significantly, that is, obtain the corresponding critical intensity; S43: Obtain and record the critical intensity corresponding to each flow point to obtain the relationship between passive regeneration intensity and flow rate; S44: Take the critical intensity at each flow rate, multiply it by the safety factor, obtain the safety threshold at that flow rate, and create a table showing how it changes with the flow rate.
6. The passive regeneration intensity control method based on carbon loading and exhaust characteristics according to claim 5, characterized in that, S5: During engine operation, the current passive regeneration intensity is calculated in real time, and the dynamic safety threshold is obtained by looking up a table based on the current exhaust volume flow rate, including: S51: During engine operation, the engine management system calculates the current passive regeneration intensity and the current exhaust volume flow rate in real time; S52: Based on the current exhaust volume flow rate and the table showing changes with flow rate, obtain the dynamic safety threshold.
7. The passive regeneration intensity control method based on carbon loading and exhaust characteristics according to claim 6, characterized in that, S6: When the passive regeneration intensity exceeds the dynamic safety threshold and the current carbon load of the diesel engine particulate filter is higher than the set lower limit of carbon load, the engine combustion parameters are actively adjusted to suppress NO2 generation until the passive regeneration intensity falls back to a safe range, at which point the suppression mode is exited, including: S61: The engine management system compares the calculated passive regeneration intensity with the dynamic safety threshold obtained by looking up the table in real time. When the passive regeneration intensity is greater than the dynamic safety threshold and the current carbon load of the diesel particulate filter is higher than the set lower limit of carbon load, the engine management system determines that it has entered the excessive passive regeneration state. S62: The engine management system actively adjusts engine combustion parameters to reduce NO2 concentration in order to reduce the intensity of passive regeneration reaction. S63: The adjustment measures include adjusting one or more combinations of exhaust gas recirculation rate, injection timing, injection pressure, intake throttle valve, and VGT opening; S64: The adjustment range adopts a closed-loop control strategy to continuously monitor the adjustment effect.
8. The passive regeneration intensity control method based on carbon loading and exhaust characteristics according to claim 7, characterized in that, Adjusting the exhaust gas recirculation rate includes: Increase the amount of exhaust gas recirculation, reduce the oxygen concentration and combustion temperature in the combustion chamber, and inhibit NO2 formation; The range of exhaust gas recirculation rate is set according to engine operating conditions and emission requirements; The exhaust gas recirculation valve is controlled by electric or pneumatic means. During the adjustment of the exhaust gas recirculation rate, the changes in exhaust temperature and oxygen concentration are monitored.
9. The passive regeneration intensity control method based on carbon loading and exhaust characteristics according to claim 8, characterized in that, Adjusting the injection timing includes: Delaying the injection timing lowers the peak combustion temperature and reduces NO2 formation; The range of fuel injection timing is set according to engine speed and load; The injectors employ high-pressure common rail or electronically controlled unit pump technology, and during the injection timing adjustment process, the engine's power and fuel economy are monitored.
10. The passive regeneration intensity control method based on carbon loading and exhaust characteristics according to claim 9, characterized in that, Closed-loop control strategies include: Continuously monitor the rate of change of NO2 concentration and carbon loading after adjustment, and recalculate the real-time passive regeneration intensity; The recalculated passive regeneration intensity is compared with the dynamic safety threshold to determine whether further adjustment is needed. Once the passive regeneration intensity drops back to a safe range and remains there for a certain period of time, the system determines that the risk to the carbon cake layer has been eliminated. The engine combustion parameters are gradually restored to normal, and the passive regeneration suppression mode is smoothly exited.