Urea injection control method and system of national 7 diesel engine based on real-time parameter monitoring

Abstract

The invention discloses a real-time parameter monitoring-based urea injection control method and system for a national 7 diesel engine, which are applied to a controller, and the method comprises the following steps: measuring the NOx concentration in real time through a NOx sensor arranged at a two-stage SCR inlet, querying an NO2 proportion coefficient from an NO2 model in combination with the operation state of an engine, and calculating to obtain the NO2 concentration; the temperature and the NO2 concentration before SCR are monitored in real time and serve as input parameters of an N2O generation difficulty model; according to N2O generation characteristics, an N2O generation difficulty model based on the temperature and the NO2 concentration is established, and the N2O generation difficulty coefficient of the two-stage SCR is calculated; according to the N2O generation difficulty coefficient, the first-stage urea injection amount is dynamically adjusted; and the NOx conversion efficiency of the two-stage SCR is monitored. Therefore, according to the invention, through real-time monitoring and adjustment, the N2O emission is effectively reduced.

Description

Technical Field

[0001] The embodiments of the present invention relate to the technical field of diesel engine aftertreatment, and in particular to a urea injection control method and system for a National VII diesel engine based on real-time parameter monitoring. Background Art

[0002] Europe has released the next stage of Euro VII emission regulations. The NOx emission limit is very small, much lower than the current Euro VI regulations. Urea needs to be injected to convert NOx into N2 under the catalytic action of SCR to achieve NOx compliance. my country is carrying out technical research on the next stage of National VII regulations. Euro VII regulations will have important reference significance for the formulation of National VII regulations. The NOx limit of National VII will be stricter than Euro VII. The combustion of the diesel engine itself does not produce N2O, but the urea injected on the exhaust pipe will undergo a side reaction after thermal decomposition to NH3 to generate a large amount of polluting gas N2O. The chemical reaction of NH3 to generate N2O in the SCR and ASC catalytic units is as follows:

[0003] NO2+NH3→NH4NO3+N2+H2O

[0004] NH4NO3→N2O+H2O

[0005] NH3+O2→N2O+H2O

[0006] Among them, SCR coating material, exhaust temperature, NO2 concentration, urea injection amount, etc. will affect the generation of N2O. How to reduce N2O emissions is a difficult problem that the industry urgently needs to solve. Summary of the invention

[0007] The embodiment of the present invention provides a urea injection control method and system for a National VII diesel engine based on real-time parameter monitoring, which effectively reduces N2O emissions through real-time monitoring and adjustment.

[0008] To achieve the above objectives, in a first aspect, the present invention provides a urea injection control method for a National VII diesel engine based on real-time parameter monitoring, which is applied to a controller, and the method comprises:

[0009] Step S100, measuring the NOx concentration in real time by using the NOx sensors arranged at the inlets of the two-stage SCR, and querying the NO2 proportion coefficient from the NO2 model in combination with the engine running state to calculate the NO2 concentration;

[0010] Step S200, real-time monitoring of the temperature and NO2 concentration before the SCR as input parameters of the N2O generation difficulty model;

[0011] Step S300, according to the N2O generation characteristics, establish a N2O generation difficulty model based on temperature and NO2 concentration, and calculate the N2O generation difficulty coefficient of the two-stage SCR;

[0012] Step S400, dynamically adjusting the first-stage urea injection amount according to the N2O generation difficulty coefficient;

[0013] Step S500, monitoring the NOx conversion efficiency of the two-stage SCR.

[0014] In one embodiment of the present invention, step S100 includes:

[0015] Step S101, automatically acquiring real-time NOx concentration data through NOx sensors arranged at the inlet of the first-stage SCR and the inlet of the second-stage SCR, which are respectively denoted as Q1 and Q2;

[0016] Step S102, real-time monitoring of the engine operating status, including engine speed and circulating oil volume;

[0017] Step S103, according to the real-time acquired engine speed and circulating oil volume, automatically query the corresponding NO2 proportion coefficient at this time from the pre-stored NO2 model, and record them as R1 and R2 respectively;

[0018] Step S104, using the measured NOx concentrations Q1 and Q2 and the queried NO2 proportion coefficients R1 and R2, the NO2 concentrations at the first-stage SCR inlet and the second-stage SCR inlet are automatically calculated and recorded as M1 and M2 respectively.

[0019] In one embodiment of the present invention, step S200 includes:

[0020] Step S201, automatically monitoring the temperature sensors arranged before the first stage SCR and the second stage SCR, and obtaining exhaust temperature data in real time, which are recorded as T1 and T2 respectively;

[0021] Step S202, obtaining real-time NO2 concentration data, namely M1 and M2, from the NOx and NO2 concentration monitoring step;

[0022] Step S203, integrating the acquired exhaust temperature T1 and T2 and NO2 concentration M1 and M2 data, and automatically storing them in the internal memory;

[0023] Step S204, continuously monitor the changes in exhaust temperature and NO2 concentration, and update the stored data in real time as input parameters of the N2O generation difficulty model.

[0024] In one embodiment of the present invention, step S300 includes:

[0025] Step S301, based on research data and experience, a mathematical model is pre-established to describe the relationship between the difficulty of N2O generation and the exhaust temperature and NO2 concentration;

[0026] Step S302, automatically taking the exhaust gas temperatures T1 and T2 and NO2 concentrations M1 and M2 monitored in real time as input parameters and passing them into the N2O generation difficulty model;

[0027] Step S303, using the established mathematical model, according to the input exhaust temperature and NO2 concentration, automatically calculate the N2O generation difficulty coefficients of the first-stage SCR and the second-stage SCR, which are recorded as K1 and K2 respectively;

[0028] Among them, the smaller the difficulty coefficient, the easier it is to generate N2O, which needs to be controlled, and the larger the difficulty coefficient, the more difficult it is to generate N2O.

[0029] In one embodiment of the present invention, step S400 includes:

[0030] Step S401, automatically obtaining N2O generation difficulty coefficients K1 and K2 of the first-stage SCR and the second-stage SCR from the N2O generation difficulty model;

[0031] Step S402, determining the correction direction of urea injection based on the difficulty coefficients K1 and K2 generated by N2O;

[0032] Step S403, automatically calculating the correction coefficient L of urea injection according to the determined correction direction;

[0033] Step S404: applying the calculated correction coefficient L to the injection amount of the first-stage urea to dynamically adjust the injection amount of the first-stage urea.

[0034] In one embodiment of the present invention, step S500 includes:

[0035] Step S501, automatically obtaining real-time NOx concentration data from NOx sensors arranged before and after the catalyst, which are recorded as N1 and N2 respectively;

[0036] Step S502, using the acquired NOx concentration data, according to the formula F=(N1-N2) / N1, automatically calculate the total NOx conversion efficiency F of the two-stage SCR;

[0037] Step S503, comparing the calculated conversion efficiency F with a preset threshold or historical data to determine whether the conversion efficiency has decreased;

[0038] Step S504: if the conversion efficiency F does not decrease, the current urea injection correction coefficient L is maintained and the correction strategy is continued to be executed; if the conversion efficiency F decreases, the urea injection correction coefficient L is automatically adjusted to 1 and the correction is canceled.

[0039] In the second aspect, the present invention provides a urea injection control system for a National VII diesel engine based on real-time parameter monitoring, which is applied to a controller, and the system includes: a first calculation module, a first monitoring module, a second calculation module, a dynamic adjustment module, and a second monitoring module. The first calculation module is used to measure the NOx concentration in real time through the NOx sensor arranged at the inlet of the two-stage SCR, and inquire the NO2 proportion coefficient from the NO2 model in combination with the engine operation state to calculate the NO2 concentration. The first monitoring module is used to monitor the temperature and NO2 concentration before the SCR in real time as input parameters of the N2O generation difficulty model. The second calculation module is used to establish an N2O generation difficulty model based on temperature and NO2 concentration according to the N2O generation characteristics, and calculate the N2O generation difficulty coefficient of the two-stage SCR. The dynamic adjustment module is used to dynamically adjust the first-stage urea injection amount according to the N2O generation difficulty coefficient. And the second monitoring module is used to monitor the NOx conversion efficiency of the two-stage SCR.

[0040] In one embodiment of the present invention, the first calculation module includes: a first acquisition unit, a first monitoring unit, a query unit and a first calculation unit. The first acquisition unit is used to automatically acquire real-time NOx concentration data through NOx sensors arranged at the first-stage SCR inlet and the second-stage SCR inlet, which are respectively denoted as Q1 and Q2. The first monitoring unit is used to monitor the operating state of the engine in real time, including the engine speed and the circulating oil volume. The query unit is used to automatically query the corresponding NO2 proportion coefficient at this time from the pre-stored NO2 model according to the real-time acquired engine speed and the circulating oil volume, which are respectively denoted as R1 and R2. And the first calculation unit is used to automatically calculate the NO2 concentration at the first-stage SCR inlet and the second-stage SCR inlet using the measured NOx concentrations Q1 and Q2 and the queried NO2 proportion coefficients R1 and R2, which are respectively denoted as M1 and M2.

[0041] In a third aspect, the present invention provides an electronic device, comprising:

[0042] at least one processor; and

[0043] a memory communicatively coupled to the at least one processor;

[0044] Wherein, the memory stores instructions that can be executed by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor can execute the urea injection control method based on real-time parameter monitoring of the National VII diesel engine as described above.

[0045] In a fourth aspect, the present invention provides a computer-readable storage medium, including a computer program and instructions. When the computer program or the instructions are run on a computer, the computer executes the urea injection control method for the National VII diesel engine based on real-time parameter monitoring as described above.

[0046] Compared with the prior art, the urea injection control method and system for the National VII diesel engine based on real-time parameter monitoring according to the present invention has the following beneficial effects:

[0047] 1. Effectively reduce N2O emissions through real-time monitoring and adjustment;

[0048] 2. While reducing N2O emissions, it can maintain high NOx conversion efficiency, ensuring overall emission compliance;

[0049] 3. Automatic acquisition, processing and output are achieved without human intervention, which improves the intelligence level of system operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 It is a structural schematic diagram of an existing diesel engine aftertreatment system;

[0051] Figure 2 It is a flow chart of a urea injection control method for a National VII diesel engine based on real-time parameter monitoring in Embodiment 1 of the present invention;

[0052] Figure 3 It is a structural schematic diagram of a urea injection control system of a National VII diesel engine based on real-time parameter monitoring in Embodiment 2 of the present invention;

[0053] Figure 4 It is a schematic diagram of the structure of an electronic device in Embodiment 3 of the present invention;

[0054] Figure 5 It is a working logic flow diagram of a urea injection control method for a National VII diesel engine based on real-time parameter monitoring according to a specific embodiment of the present invention. DETAILED DESCRIPTION

[0055] The embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the embodiments of the present invention, rather than to limit the embodiments of the present invention. It is also necessary to explain that, for ease of description, only parts related to the embodiments of the present invention are shown in the accompanying drawings, rather than all structures.

[0056] Embodiment 1

[0057] Figure 2 : is a flow chart of a urea injection control method for a National VII diesel engine based on real-time parameter monitoring in Embodiment 1 of the present invention, such as Figure 2 As shown, embodiment 1 provides a urea injection control method for a National VII diesel engine based on real-time parameter monitoring, which is applied to a controller. The method includes:

[0058] Step S100, measuring the NOx concentration in real time by using the NOx sensors arranged at the inlets of the two-stage SCR, and querying the NO2 proportion coefficient from the NO2 model in combination with the engine running state to calculate the NO2 concentration;

[0059] Specifically, step S100 is a key starting step in the urea injection control method. It measures the NOx concentration in real time through the NOx sensor arranged at the inlet of the two-stage SCR, and dynamically queries the NO2 proportion coefficient from the pre-stored NO2 model in combination with the engine running state, and then calculates the NO2 concentration. This process is not only highly automated, but also highly accurate. It can reflect the distribution of NOx and NO2 in the engine exhaust in real time, and provides an important basis for the subsequent precise control of the urea injection amount. The implementation of this step has laid a solid foundation for reducing N2O emissions and optimizing the performance of the SCR system. Among them, the controller can be, for example, an on-board controller (ECU).

[0060] Step S200, real-time monitoring of the temperature and NO2 concentration before the SCR as input parameters of the N2O generation difficulty model;

[0061] Specifically, step S200 accurately captures the key factors affecting N2O generation by real-time monitoring of the exhaust temperature and NO2 concentration before the SCR, and imports these data as input parameters into the N2O generation difficulty model. This step ensures the accuracy and timeliness of the model prediction, which is crucial for dynamically adjusting the urea injection strategy to reduce N2O emissions.

[0062] Step S300, according to the N2O generation characteristics, establish a N2O generation difficulty model based on temperature and NO2 concentration, and calculate the N2O generation difficulty coefficient of the two-stage SCR;

[0063] Specifically, step S300 constructs a N2O generation difficulty model with exhaust temperature and NO2 concentration as variables based on the N2O generation characteristics. Through this model, the system can accurately calculate the N2O generation difficulty coefficient of the two-stage SCR, providing a scientific basis for optimizing urea injection strategy and reducing N2O emissions.

[0064] Step S400, dynamically adjusting the first-stage urea injection amount according to the N2O generation difficulty coefficient;

[0065] Specifically, step S400 intelligently adjusts the first-stage urea injection amount in real time according to the difficulty coefficient of N2O generation. When the difficulty coefficient indicates that N2O is easy to generate, the urea injection is reduced; otherwise, the urea injection is increased appropriately, so as to balance NOx conversion and N2O suppression, ensure that emissions meet standards, and optimize urea consumption.

[0066] Step S500, monitoring the NOx conversion efficiency of the two-stage SCR;

[0067] Specifically, step S500 focuses on monitoring the NOx conversion efficiency of the two-stage SCR system, and ensures that the treatment effect meets the expected standards through real-time monitoring. This step aims to promptly detect and respond to any efficiency decline, maintain efficient operation of the system, and ensure that exhaust emissions continue to meet standards.

[0068] In this embodiment, step S100 includes:

[0069] Step S101, automatically acquiring real-time NOx concentration data through NOx sensors arranged at the inlet of the first-stage SCR and the inlet of the second-stage SCR, which are respectively denoted as Q1 and Q2;

[0070] Specifically, a high-precision NOx sensor is installed at the entrance of the first-stage SCR system, and a high-precision NOx sensor is also installed at the entrance of the second-stage SCR system; ensure that the sensor installation position is reasonable and can accurately reflect the NOx concentration entering each level of the SCR system. The two NOx sensors measure the NOx concentration at their respective entrances in real time. The sensor converts the measured NOx concentration data into electrical signals and transmits them to the control system through the data line (the controller has a built-in control system). The data acquisition module in the control system receives and processes these electrical signals and converts them into specific NOx concentration values. The control system marks the NOx concentration value at the entrance of the first-stage SCR as Q1. Similarly, the NOx concentration value at the entrance of the second-stage SCR is marked as Q2. These data will be used in subsequent calculations and analysis processes.

[0071] For example, when a diesel engine is in normal operation, its exhaust treatment system adopts two-stage SCR technology. At a certain moment, the control system obtains real-time NOx concentration data through the NOx sensors arranged at the first and second SCR inlets: NOx concentration at the first SCR inlet (Q1): 300ppm, which indicates that the NOx concentration in the exhaust gas is 300ppm before the first SCR system is processed. This value will be used as one of the basic data for calculating the NO2 concentration at the first SCR inlet. NOx concentration at the second SCR inlet (Q2): 250ppm, after the first SCR system is processed, the NOx concentration in the exhaust gas is reduced to 250ppm. This value is also important because it reflects the treatment effect of the first SCR system and will be used as one of the basic data for calculating the NO2 concentration at the second SCR inlet. Through these real-time NOx concentration data (Q1 and Q2), the control system can further combine the engine's operating status and other related parameters to perform subsequent calculations and analysis, such as querying the NO2 proportion coefficient, calculating the NO2 concentration, and evaluating the difficulty of N2O generation, thereby providing a scientific basis for dynamically adjusting the urea injection amount.

[0072] Step S102, real-time monitoring of the engine's operating status, including engine speed and circulating oil volume, as a basis for subsequent calculation of the NO2 ratio;

[0073] Specifically, the engine is equipped with a speed sensor and an oil level sensor (or similar equipment, such as a fuel injection control unit). The speed sensor measures the engine speed in real time, and converts the speed signal into an electrical signal and transmits it to the control system. The oil level sensor (or related equipment) monitors the circulating oil volume of the engine, and also converts the oil level information into an electrical signal and transmits it to the control system. The data acquisition module in the control system receives electrical signals from the speed sensor and the oil level sensor, and converts these electrical signals into specific numerical values, namely the real-time speed and circulating oil volume of the engine. The control system stores the received speed and oil level data in the internal memory for subsequent query and use. As the engine runs, these data will be continuously updated to reflect the current actual operating status of the engine.

[0074] For example, a diesel engine is running at a stable speed for long-distance transportation tasks. At this time, the control system obtains the following real-time data through the speed sensor and the oil quantity sensor: Engine speed: 1800 rpm, which indicates that the engine is currently running at a medium speed, suitable for long-distance stable driving. Circulating oil volume: 50 liters / hour, which means that the engine consumes about 50 liters of fuel per hour to maintain its operation. The control system stores these data in the internal memory and calls them at any time when needed. For example, when calculating the NO2 proportion coefficient in step S103, the control system will query the corresponding proportion coefficient from the pre-stored NO2 model according to the current engine speed and circulating oil volume. If the model shows that the proportion of NO2 in NOx is about 15% at the current speed and oil volume, then this information will be used for the subsequent calculation of the NO2 concentration at the first and second stage SCR inlets. Through such real-time monitoring and data acquisition processing, the control system can accurately grasp the operating status of the engine and provide accurate basic data support for subsequent urea injection control.

[0075] Step S103, according to the real-time acquired engine speed and circulating oil volume, automatically query the corresponding NO2 proportion coefficient at this time from the pre-stored NO2 model, and record them as R1 and R2 respectively;

[0076] Specifically, ensure that the control system has received and stored the real-time acquired engine speed and circulating oil volume data (as described in step S102). Verify whether the pre-stored NO2 model is available and contains data points covering the current engine speed and circulating oil volume range. The control system determines the query conditions in the NO2 model based on the current engine speed and circulating oil volume. Use an appropriate query algorithm (such as interpolation, lookup table, etc.) to find the NO2 share coefficient that best matches the current engine state in the NO2 model. If the model is discrete (such as a lookup table form), it may be necessary to calculate the NO2 share coefficient of non-direct corresponding points by interpolation. The queried NO2 share coefficient is stored in the control system for subsequent calculations. If any problems are encountered during the query process (such as missing data points, model range mismatch, etc.), the control system should be able to identify and take corresponding error handling measures.

[0077] For example, the current speed of a diesel engine is 1800 rpm and the circulating oil volume is 50 liters / hour. Based on these real-time data, the control system queries the corresponding NO2 proportion coefficient in the pre-stored NO2 model. Assume that the NO2 model is a two-dimensional lookup table, which contains the NO2 proportion coefficients under different combinations of speed and circulating oil volume. The control system first determines the position of the current engine speed (1800 rpm) and the circulating oil volume (50 liters / hour) in the lookup table. If these two values ​​happen to match a data point in the lookup table, the NO2 proportion coefficient corresponding to the data point is directly read. If it does not match, the control system will use interpolation (such as bilinear interpolation) to calculate the NO2 proportion coefficient closest to the current value. Assume that after query and interpolation calculation, the NO2 proportion coefficient obtained is 0.15 (that is, the proportion of NO2 in NOx is 15%). This NO2 proportion coefficient will be used in the subsequent steps to calculate the NO2 concentration at the first and second stage SCR inlets (as described in step S104). Through such a query process, the control system can accurately obtain the NO2 ratio according to the real-time operating status of the engine, providing key parameters for subsequent urea injection control.

[0078] Step S104, using the measured NOx concentrations Q1 and Q2 and the queried NO2 proportion coefficients R1 and R2, the NO2 concentrations at the first-stage SCR inlet and the second-stage SCR inlet are automatically calculated, which are recorded as M1 and M2 respectively; wherein M1 = Q1 × R1, M2 = Q2 × R2;

[0079] Specifically, ensure that the NOx concentration data at the first and second stage SCR inlets have been obtained, recorded as Q1 and Q2 respectively (the unit is usually ppm). Ensure that the NO2 proportion coefficient corresponding to the current engine speed and circulating oil volume has been queried through step S103, recorded as R1 and R2 respectively (unitless, indicating the proportion of NO2 in NOx). Use the formula Mi=Qi×Ri to calculate the NO2 concentration at the inlet of each stage of SCR, where i represents the number of stages (1 or 2). For the first stage SCR inlet, calculate M1=Q1×R1, and for the second stage SCR inlet, calculate M2=Q2×R2. Store the calculated NO2 concentrations (M1 and M2) in the control system for subsequent use.

[0080] For example, the operating data of a diesel engine at a certain moment is as follows:

[0081] The NOx concentration at the first stage SCR inlet is Q1 = 300ppm;

[0082] The NOx concentration at the inlet of the second stage SCR is Q2 = 250ppm;

[0083] The NO2 proportion coefficient queried in step S103: first level R1 = 0.15, second level R2 = 0.12;

[0084] Next, calculation is performed according to step S104:

[0085] The NO2 concentration at the first stage SCR inlet is M1 = Q1 × R1 = 300ppm × 0.15 = 45ppm;

[0086] The NO2 concentration at the inlet of the second stage SCR is M2 = Q2 × R2 = 250ppm × 0.12 = 30ppm;

[0087] In this way, the NO2 concentration at the first and second stage SCR inlets is obtained, and these data will be used in the subsequent steps to evaluate the difficulty of N2O generation and adjust the urea injection amount accordingly. By refining step S104, it can be ensured that the actual operating state of the engine (reflected by the NO2 proportion coefficient) is taken into account when calculating the NO2 concentration, thereby providing more accurate basic data for subsequent urea injection control.

[0088] In this embodiment, step S200 includes:

[0089] Step S201, automatically monitoring the temperature sensors arranged before the first stage SCR and the second stage SCR, and obtaining exhaust temperature data in real time, which are recorded as T1 and T2 respectively;

[0090] Specifically, high-precision temperature sensors are installed at the inlet of the first-stage and second-stage SCR systems. Ensure that the sensors can accurately measure and reflect the exhaust temperature at the inlet of the SCR system. The temperature sensor detects the temperature at the inlet of the SCR in real time and converts the temperature value into an electrical signal. These electrical signals are transmitted to the data acquisition module in the control system through the data line. The data acquisition module receives the electrical signal from the temperature sensor and converts it into a specific temperature value (usually in degrees Celsius). The converted temperature value is stored in the internal memory of the control system for subsequent analysis and use. The control system continuously monitors the output of the temperature sensor and updates the stored temperature data in real time. If the temperature value changes significantly or exceeds the preset range, the control system should be able to trigger the corresponding alarm or adjustment measures.

[0091] For example, a diesel engine is running, and its exhaust gas treatment system includes two-stage SCR. Temperature sensors are installed at the inlet of the first and second stage SCR systems to monitor the exhaust temperature. At a certain moment, the temperature sensor at the inlet of the first stage SCR detects that the exhaust temperature is 400 degrees Celsius, and converts this temperature value into an electrical signal and sends it to the control system. At the same time, the temperature sensor at the inlet of the second stage SCR also detects the exhaust temperature, assuming it is 350 degrees Celsius, and also sends the temperature value to the control system. After receiving the electrical signals from the two temperature sensors, the control system converts them into specific temperature values: 400 degrees Celsius and 350 degrees Celsius respectively. These temperature values ​​are stored in the internal memory of the control system, marked as the first stage SCR inlet temperature T1 and the second stage SCR inlet temperature T2. In step S300, these temperature values ​​will be used as input parameters together with the NO2 concentration to calculate the N2O generation difficulty coefficient of the two-stage SCR. According to the effect of temperature on N2O generation (usually N2O generation decreases at high temperature, but too high or too low temperature may affect the catalytic efficiency of SCR), the control system will evaluate the difficulty of N2O generation under the current conditions and adjust the urea injection amount accordingly. By refining step S201, it is possible to ensure real-time and accurate monitoring of the temperature at the SCR inlet, providing reliable data support for subsequent N2O generation evaluation and control.

[0092] Step S202, obtaining real-time NO2 concentration data, namely M1 and M2, from the NOx and NO2 concentration monitoring step as important parameters affecting N2O emissions;

[0093] Specifically, in step S104, the NO2 concentration (M1 and M2) at the inlet of the first and second stage SCR has been calculated by the NOx concentration (Q1 and Q2) and the NO2 proportion coefficient (R1 and R2). These data will be used directly in step S202 without re-measurement. However, in actual applications, if the control system needs to continuously monitor the NO2 concentration, a special NO2 sensor can be installed at the SCR inlet to obtain data in real time. The calculated or real-time obtained NO2 concentration values ​​(M1 and M2) are stored in the internal memory of the control system. Ensure the accuracy and integrity of the data for subsequent analysis and use. If the control system uses a real-time sensor to obtain the NO2 concentration, it should be ensured that the sensor data can be updated to the control system in real time. If the NO2 concentration is obtained by calculation, when the NOx concentration or the NO2 proportion coefficient changes, the NO2 concentration value should be recalculated and updated. Verify the obtained NO2 concentration data to ensure that it is within a reasonable range and consistent with expectations. If abnormal data is found, the sensor or calculation process should be checked in time to troubleshoot. The verified NO2 concentration data (M1 and M2) are used as one of the input parameters of the N2O generation difficulty model. Together with other relevant parameters (such as exhaust temperature, urea injection amount, etc.), they are used to evaluate the difficulty of N2O generation and adjust the urea injection strategy accordingly.

[0094] For example, at a certain moment, the NO2 concentrations at the first and second stage SCR inlets calculated by step S104 are M1=45ppm and M2=30ppm respectively. These data will be stored in the control system and used for subsequent N2O generation evaluation. If the system uses a real-time sensor to monitor the NO2 concentration, when the sensor detects a change in the NO2 concentration (for example, a change in the NOx emission characteristics due to engine operating condition adjustment), the new NO2 concentration value will be automatically updated to the control system and replace the old data. In step S300, the control system will use the updated NO2 concentration value (and other parameters such as exhaust temperature) as input to run the N2O generation difficulty model. The model calculates the N2O generation difficulty coefficient under the current conditions based on the input parameters, and the control system adjusts the urea injection amount based on the coefficient to optimize the NOx conversion efficiency and N2O emission performance. Through the above detailed steps and example descriptions, the role and implementation method of step S202 in the urea injection control process can be clearly understood.

[0095] Step S203, integrating the acquired exhaust temperature T1 and T2 and NO2 concentration M1 and M2 data, and automatically storing them in the internal memory for subsequent processing and calling;

[0096] Specifically, before this step, the system has acquired the exhaust temperature (T1 and T2) and NO2 concentration (M1 and M2) at the inlet of the first and second stage SCR in real time through temperature sensors and NO2 concentration monitoring equipment (which may be calculated through NOx sensors and NO2 proportion coefficients, or directly measured through NO2 sensors). The system integrates these scattered data (T1, T2, M1, M2) to form a complete data set. This process involves, for example, data formatting, unit unification, and abnormal value checking to ensure the accuracy and efficiency of subsequent processing. The integrated data set should contain all necessary input parameters so that it can be directly used as input for the N2O generation difficulty model in the future. The system automatically stores the integrated data set in the internal memory. This internal memory can be, for example, RAM, Flash memory, or other types of non-volatile storage devices.

[0097] Step S204, continuously monitoring the changes in exhaust temperature and NO2 concentration, and updating the stored data in real time as input parameters of the N2O formation difficulty model, to ensure that the parameters used for calculating the N2O formation difficulty model are the latest;

[0098] Specifically, the system continuously monitors the changes in exhaust temperature and NO2 concentration through temperature sensors and NO2 concentration monitoring devices installed at the inlet of the SCR (which may be direct NO2 sensors, or calculated through NOx sensors and NO2 proportion coefficients). These sensors collect data in real time and convert the data into electrical signals or digital signals for subsequent processing. The data acquisition module in the system is responsible for receiving signals from the sensors and converting them into processable temperature values ​​and NO2 concentration values. The collected data is preliminarily processed, including filtering, denoising, calibration, etc., to improve the accuracy and reliability of the data. The latest processed temperature (T1 and T2) and NO2 concentration (M1 and M2) data are automatically updated to the internal memory, overwriting the old data. Ensure that the stored data always reflects the current exhaust temperature and NO2 concentration status. The updated data will be used as input parameters for the N2O generation difficulty model. When the model needs to calculate the N2O generation difficulty coefficient, these latest data will be retrieved directly from the internal memory. Through continuous monitoring and real-time update mechanisms, the system can ensure that the parameters used for the calculation of the N2O generation difficulty model are always up to date. This is crucial to improving the prediction accuracy of the model and the real-time performance of urea injection control. Through the continuous monitoring and real-time update mechanism of step S204, the urea injection control system can ensure that the latest exhaust temperature and NO2 concentration data are always used as input parameters of the N2O generation difficulty model under dynamically changing working conditions, thereby improving the accuracy and real-time performance of urea injection control.

[0099] In this embodiment, step S300 includes:

[0100] Step S301, based on research data and experience, a mathematical model is pre-established to describe the relationship between the difficulty of N2O generation and the exhaust temperature and NO2 concentration;

[0101] Specifically, first, a large amount of experimental data needs to be collected, which should cover the N2O generation under different exhaust temperature and NO2 concentration conditions. These data can be obtained through laboratory experiments, engine bench tests or actual vehicle operation. The collected data are analyzed in detail to identify the influence of exhaust temperature and NO2 concentration on the difficulty of N2O generation. For example, statistical analysis and regression analysis are involved to determine the quantitative relationship between various factors. Based on the results of data analysis, a mathematical model is constructed to describe the relationship between the difficulty of N2O generation and exhaust temperature and NO2 concentration. This model can be a polynomial regression model, a neural network model, a support vector machine model, etc. The specific choice depends on the characteristics of the data and the purpose of modeling. The model is verified using a data set that is not involved in the model construction to evaluate its prediction accuracy and generalization ability. If the model prediction results are highly consistent with the actual data, it means that the model is successfully built; otherwise, the model needs to be adjusted and optimized. The model is optimized according to the verification results to improve its prediction accuracy and stability. The optimization methods may include adjusting model parameters, adding input features, improving model structure, etc. The optimized model is embedded into the urea injection control system to calculate the N2O generation difficulty coefficient in real time and adjust the urea injection amount according to the coefficient.

[0102] For example, through a series of experiments, we obtained the data of N2O generation under different exhaust temperature (T) and NO2 concentration (M). After data analysis, we found that there is the following relationship between the difficulty of N2O generation (K) and the exhaust temperature and NO2 concentration:

[0103] K=a·T 2 +b·T·M+c·M 2 +d·T+e·M+f

[0104] Among them, (a, b, c, d, e, f) are model parameters obtained through regression analysis. In order to build this model, the least squares method can be used to fit the experimental data first to obtain the specific values ​​of the model parameters. Then, the model is verified and optimized using methods such as cross-validation. Finally, a mathematical model that can accurately describe the relationship between the difficulty of N2O generation and the exhaust temperature and NO2 concentration is obtained. In the urea injection control system, the real-time exhaust temperature (T1 and T2) and NO2 concentration (M1 and M2) data will be input into this model to calculate the N2O generation difficulty coefficient (K1 and K2) of the two-stage SCR. Then, the urea injection amount is adjusted according to these coefficients to reduce the generation of N2O while maintaining efficient conversion of NOx.

[0105] Step S302, automatically taking the exhaust gas temperatures T1 and T2 and NO2 concentrations M1 and M2 monitored in real time as input parameters and passing them into the N2O generation difficulty model;

[0106] Specifically, before this step, the system has monitored the exhaust temperature (T1 and T2) and NO2 concentration (M1 and M2) data in real time through the temperature sensor and NO2 concentration monitoring device installed at the SCR inlet (which can be a direct NO2 sensor, or calculated through a NOx sensor and NO2 ratio coefficient). Before the data is passed into the model, the system should verify the data to ensure its accuracy, completeness and rationality. This includes checking whether the data is within the expected range, whether there are abnormal values, etc. Once the data is verified, the system will automatically use these data (T1, T2, M1, M2) as input parameters, and pass them into the pre-established N2O generation difficulty model in the format and order required by the model. After receiving the input parameters, the model will calculate according to its internal algorithm and formula, and output the corresponding N2O generation difficulty coefficient (such as K1 and K2). These coefficients reflect the difficulty of N2O generation in the SCR system under the current exhaust temperature and NO2 concentration conditions.

[0107] Step S303, using the established mathematical model, according to the input exhaust temperature and NO2 concentration, automatically calculate the N2O generation difficulty coefficients of the first-stage SCR and the second-stage SCR, which are recorded as K1 and K2 respectively;

[0108] The smaller the difficulty coefficient, the easier it is to generate N2O and the more control is needed. The larger the difficulty coefficient, the more difficult it is to generate N2O. The controller uses the calculated K1 and K2 in the subsequent urea injection correction step. During the actual operation, the controller can continuously collect new data and update and optimize the N2O generation difficulty model as needed to improve the accuracy and adaptability of the model.

[0109] Specifically, in this step, it is first necessary to call a pre-established mathematical model. This model is built based on a large amount of experimental data and theoretical research, and can describe the complex relationship between the difficulty of N2O generation and parameters such as exhaust temperature and NO2 concentration. Real-time input exhaust temperature (T1 and T2) and NO2 concentration (M1 and M2) data are obtained from the system's monitoring module. These data have been verified to ensure their accuracy and effectiveness. T1 and M1 are used as input parameters for the first-stage SCR, and T2 and M2 are used as input parameters for the second-stage SCR, respectively, and are passed into the mathematical model. The model processes and calculates these input parameters according to internal algorithms and formulas, and finally outputs the N2O generation difficulty coefficients K1 and K2 for the first and second-stage SCR. The calculated K1 and K2 are output to the control system for use in subsequent steps (such as urea injection amount adjustment).

[0110] For example, the real-time monitoring data of a diesel engine at a certain moment is as follows:

[0111] First stage SCR inlet exhaust temperature T1 = 400°C

[0112] Second stage SCR inlet exhaust temperature T2 = 350°C

[0113] NO2 concentration at the first stage SCR inlet M1 = 45ppm

[0114] Second stage SCR inlet NO2 concentration M2 = 30ppm

[0115] These data have been verified by the system and confirmed to be correct. Next, the system uses these data as input parameters and calls the pre-established N2O generation difficulty model for calculation.

[0116] For example, the model is an algorithm based on polynomial regression, and its internal formula may be:

[0117] K=a·T 2 +b·T·M+c·M 2 +d·T+e·M+f

[0118] Among them, parameters a, b, c, d, e, and f are obtained through training data. For the first-stage SCR: input parameters: T = 400 ° C, M = 45ppm, substitute into the model formula to calculate the value of K1; for the second-stage SCR: input parameters: T = 350 ° C, M = 30ppm, also substitute into the model formula to calculate the value of K2. After calculation, the results are: K1 = 0.6 (indicating that N2O generation in the first-stage SCR is relatively easy), K2 = 0.8 (indicating that N2O generation in the second-stage SCR is relatively difficult). These difficulty coefficients will serve as an important basis for subsequent adjustment of urea injection. For example, if K1 is small and K2 is large, the system may reduce the first-stage urea injection to reduce N2O generation, and may increase the second-stage urea injection to ensure efficient NOx conversion. And vice versa. Through such a dynamic adjustment strategy, the system can optimize urea consumption and the overall performance of the SCR system while meeting emission regulations.

[0119] In this embodiment, step S400 includes:

[0120] Step S401, automatically obtaining N2O generation difficulty coefficients K1 and K2 of the first-stage SCR and the second-stage SCR from the N2O generation difficulty model;

[0121] Specifically, in this step, the control system first accesses the pre-established N2O generation difficulty model. This model has completed the calculation based on the input exhaust temperature (T1 and T2) and NO2 concentration (M1 and M2), and outputs the corresponding N2O generation difficulty coefficient. The control system extracts the N2O generation difficulty coefficients of the first-stage SCR and the second-stage SCR from the model, which are recorded as K1 and K2 respectively. These coefficients represent the difficulty of N2O generation in the two-stage SCR system under the current operating conditions.

[0122] In actual application, step S401 is an automated link in the urea injection control system. When the engine is running, the control system monitors the exhaust temperature and NO2 concentration at the SCR inlet in real time, and inputs these data into the N2O generation difficulty model. After the model completes the calculation, the control system automatically obtains the K1 and K2 coefficients from the model and adjusts the urea injection amount according to these coefficients. In this way, the system can dynamically optimize the performance of the SCR system according to the current operating conditions, reduce the generation of N2O while maintaining efficient NOx conversion. By automatically obtaining the N2O generation difficulty coefficient, the urea injection control system can significantly improve the accuracy and real-time performance of emission control, thereby better meeting the increasingly stringent emission regulations.

[0123] Step S402, based on the difficulty coefficients K1 and K2 for N2O generation, determine the correction direction of urea injection; if K1 is small and K2 is large, it means that the first-stage SCR is prone to generate N2O, and a reduction correction is required; if K1 is large and K2 is small, it means that the second-stage SCR is not prone to generate N2O, and an increase correction can be made;

[0124] Specifically, K1 represents the N2O generation difficulty coefficient of the first-stage SCR. The smaller the value, the easier it is to generate N2O, and the larger the value, the greater the generation difficulty. K2 represents the N2O generation difficulty coefficient of the second-stage SCR. Similarly, the smaller the value, the easier it is to generate N2O, and the larger the value, the greater the generation difficulty. K1 is small and K2 is large: In this case, it means that N2O is easy to generate in the first-stage SCR, but it is relatively difficult to generate in the second-stage SCR. In order to reduce the generation of N2O in the first-stage SCR and ensure the efficient conversion of NOx, it is necessary to reduce the urea injection amount of the first stage (i.e., injection reduction correction). After the injection reduction, although the NOx converted by the first-stage SCR will decrease, the second-stage SCR may increase the urea injection amount to maintain the overall NOx conversion efficiency due to the increase in the NOx concentration received. Since the second-stage SCR is not easy to generate N2O at this time, increasing the urea injection amount will not lead to a significant increase in N2O emissions. K1 is large and K2 is small: On the contrary, if K1 is large and K2 is small, it means that N2O is relatively difficult to generate in the first-stage SCR, but it is easy to generate in the second-stage SCR. At this time, in order to optimize the overall emission performance, it is possible to consider increasing the urea injection amount in the first-stage SCR (i.e., injection correction) to convert more NOx and reduce the NOx concentration reaching the second-stage SCR. Since the second-stage SCR is not easy to generate N2O at this time, reducing the urea injection amount will not lead to a significant decrease in NOx conversion efficiency, and it will also help reduce N2O emissions. Based on the comparison results of K1 and K2, the control system will formulate corresponding urea injection correction strategies. These strategies will guide the increase or decrease of urea injection amount to achieve the purpose of reducing N2O emissions and maintaining efficient NOx conversion. In addition, the correction of urea injection is real-time and dynamic. As the engine operating conditions change (such as load, speed, etc.), the values ​​of K1 and K2 will also change. Therefore, the control system needs to continuously monitor these coefficients and adjust the urea injection amount in real time as needed. Through the decision-making process of step S402, the urea injection control system can intelligently adjust the urea injection amount according to the current SCR system state and emission performance requirements, thereby achieving a better emission control effect.

[0125] Step S403, automatically calculating the correction coefficient L of urea injection according to the determined correction direction; wherein, if a correction of reduced injection is required, a correction coefficient L less than 1 is output; if a correction of increased injection is required, a correction coefficient L greater than 1 is output;

[0126] Specifically, the correction coefficient L is a proportional factor for adjusting the urea injection amount. When L is less than 1, it means that the urea injection amount needs to be reduced (injection reduction correction); when L is greater than 1, it means that the urea injection amount needs to be increased (injection increase correction); when L is equal to 1, it means that the urea injection amount does not need to be adjusted. According to the correction direction determined in step S402, the control system will automatically calculate the value of the correction coefficient L. If a reduction correction is required (i.e., K1 is smaller and K2 is larger), the control system will output a correction coefficient L less than 1 according to a preset algorithm or lookup table. The specific size of this L value depends on the specific values ​​of K1 and K2 and the control strategy of the system. Generally, the smaller the L value, the larger the amount of reduction. If an increase correction is required (i.e., K1 is larger and K2 is smaller), the control system will also output a correction coefficient L greater than 1 according to a preset algorithm or lookup table. The specific size of the L value also depends on K1, K2 and the control strategy. The larger the L value, the larger the amount of increase. The calculated correction coefficient L will be directly applied to the calculation of the urea injection amount. Specifically, the originally planned urea injection amount is multiplied by the correction coefficient L to obtain the adjusted urea injection amount.

[0127] For example, if the originally planned urea injection amount is X units, and the correction coefficient L is 0.8 (indicating that a reduction in injection is required), the adjusted urea injection amount will be 0.8X units; if the correction coefficient L is 1.2 (indicating that an increase in injection is required), the adjusted urea injection amount will be 1.2X units. The calculation of the correction coefficient L should be real-time, that is, as the engine operating conditions change (such as load, speed, etc.), the control system should continuously monitor the values ​​of K1 and K2, and calculate and adjust the correction coefficient L in real time as needed to ensure the optimization of the urea injection amount. When calculating the correction coefficient L, the control system can also consider the safety limit of the urea injection amount. For example, even if an increase in injection correction is required, the urea injection amount cannot exceed the maximum allowable value of the system; similarly, even if a reduction in injection correction is required, the urea injection amount cannot be lower than the minimum value required to maintain the normal operation of the SCR system. By automatically calculating and applying the correction coefficient L, the urea injection control system can flexibly adjust the urea injection amount according to the current SCR system status and emission performance requirements, thereby achieving a better emission control effect.

[0128] Step S404: Apply the calculated correction coefficient L to the injection amount of the first-stage urea, and adjust the actual urea injection amount by multiplying it by L. In this way, in the first-stage SCR, the injection amount of urea is dynamically adjusted according to the difficulty of generating N2O.

[0129] After correcting the urea injection amount, the NOx conversion efficiency and N2O emissions of the two-stage SCR are continuously monitored. If the conversion efficiency decreases or the N2O emissions increase, the controller will automatically adjust the correction factor L to ensure the overall emission compliance and optimization of system performance.

[0130] Specifically, before this step, the system has determined the correction direction of urea injection according to the N2O generation difficulty coefficients K1 and K2, and calculated the corresponding correction coefficient L. This L value is a proportional factor used to adjust the urea injection amount. Before there is a correction coefficient L, the system will calculate a basic first-stage urea injection amount according to the current engine operating conditions (such as speed, load, etc.) and other relevant parameters. This basic injection amount is set based on meeting the NOx conversion efficiency requirements. In step S404, the system multiplies the calculated correction coefficient L by the basic first-stage urea injection amount to obtain the adjusted actual injection amount. That is: actual injection amount = basic injection amount × L. In this way, the urea injection amount can be dynamically adjusted according to the difficulty of N2O generation. If L is less than 1, the actual injection amount will decrease, which helps to reduce the generation of N2O in the first-stage SCR; if L is greater than 1, the actual injection amount will increase, which can help improve the NOx conversion efficiency (although this is usually done when it is determined that the second-stage SCR is not easy to generate N2O). The adjusted urea injection amount will be sent to the urea injection system to perform the injection operation. In this way, urea can be injected into the SCR system in an optimized amount to achieve the expected emission control effect. After urea injection, the system will continue to monitor the performance and emissions of the SCR system. If it is found that the adjusted injection amount does not achieve the expected effect (such as a decrease in NOx conversion efficiency or an increase in N2O emissions), the system may re-evaluate the N2O generation difficulty coefficients K1 and K2, and recalculate the correction factor L for further adjustments.

[0131] In actual application, the execution of step S404 is highly automated and does not require manual intervention. The urea injection control system will calculate the optimal urea injection amount in real time according to the engine operating conditions and the SCR system status, and ensure the stability and optimization of emission performance through a dynamic adjustment mechanism. This intelligent control method not only improves the accuracy of emission control, but also effectively reduces urea consumption and operating costs.

[0132] In this embodiment, step S500 includes:

[0133] Step S501, automatically obtaining real-time NOx concentration data from NOx sensors arranged before and after the catalyst, which are recorded as N1 and N2 respectively;

[0134] Specifically, step S501 is an important part of the urea injection control process, which involves real-time monitoring of the catalytic conversion efficiency of the SCR system. In this step, the system will first automatically obtain real-time NOx concentration data from the NOx sensors arranged before and after the catalyst (i.e., the SCR system). Specifically, the NOx sensor before the catalyst measures the NOx concentration in the original exhaust gas before being processed by the SCR system, and this data is marked as N1. The NOx sensor after the catalyst measures the NOx concentration in the exhaust gas after being processed by the SCR system, and this data is marked as N2. These two NOx concentration data are crucial for evaluating the conversion efficiency of the SCR system. By comparing the values ​​of N1 and N2, the system can calculate the conversion efficiency of the SCR system for NOx, that is, what proportion of NOx is successfully converted into harmless nitrogen and water when passing through the SCR system. This conversion efficiency is one of the key indicators for measuring the performance of the SCR system and an important basis for adjusting the urea injection control strategy. After obtaining the N1 and N2 data, the system usually calculates the conversion efficiency immediately and uses the results in the subsequent urea injection amount adjustment decision. If the conversion efficiency is lower than the preset threshold, it means that the current urea injection amount may be insufficient or excessive, and corresponding adjustments need to be made to optimize the performance of the SCR system. Therefore, step S501 is not only a necessary step in the urea injection control process, but also one of the key links to ensure efficient and stable operation of the SCR system.

[0135] Step S502, using the acquired NOx concentration data, according to the formula F=(N1-N2) / N1, automatically calculate the total NOx conversion efficiency F of the two-stage SCR;

[0136] Specifically, step S502 is a core calculation link in the urea injection control process, which evaluates the performance of the SCR system based on the NOx concentration data (N1 and N2) before and after the catalyst obtained in step S501. In this step, the system uses a simple mathematical formula to calculate the total NOx conversion efficiency F of the two-stage SCR. Specifically, the formula F = (N1-N2) / N1 is used to quantify the SCR system's ability to convert NOx, where N1 represents the NOx concentration before the catalyst (i.e., untreated), and N2 represents the NOx concentration after the catalyst (i.e., after being treated by the SCR system). By executing this formula, the system can automatically calculate the F value, that is, the total conversion efficiency of the two-stage SCR system for NOx. This efficiency value reflects the ability of the SCR system to remove NOx pollutants and is one of the key indicators for evaluating the performance of the system. If the F value is high, it means that the SCR system can effectively convert NOx into harmless substances and the emission control effect is good; on the contrary, if the F value is low, it may mean that there are some problems in the system, such as insufficient urea injection, catalyst aging or blockage, etc., which require further inspection and adjustment. Therefore, step S502 is not only a simple mathematical calculation process, but also a crucial feedback link in the urea injection control system. It helps the system to understand the operating status of the SCR system in real time and adjust the urea injection strategy as needed to ensure that emissions meet the standards and optimize system performance.

[0137] Step S503, comparing the calculated conversion efficiency F with a preset threshold or historical data to determine whether the conversion efficiency has decreased;

[0138] Specifically, the system compares and analyzes the conversion efficiency F with the preset threshold or historical data. The preset threshold is the minimum conversion efficiency standard set according to emission regulations and system performance requirements, while the historical data records the system's conversion efficiency performance under different operating conditions. By comparison, the system can quickly determine whether the current conversion efficiency is lower than the threshold or has decreased compared to the historical data, thereby evaluating whether the SCR system is operating normally and whether the urea injection strategy needs to be adjusted to maintain or improve the conversion efficiency.

[0139] Step S504: if the conversion efficiency F does not decrease, the current urea injection correction coefficient L is maintained and the correction strategy is continued; if the conversion efficiency F decreases, it means that the current correction strategy may not be conducive to the conversion of NOx, and the controller will automatically adjust the urea injection correction coefficient L to 1 and cancel the correction to ensure the compliance of NOx emissions;

[0140] After the correction is cancelled, the NOx conversion efficiency and N2O emissions will be continuously monitored. If the conversion efficiency is restored or the N2O emissions are reduced, the controller can reconsider whether the urea injection correction is needed.

[0141] Specifically, step S504 is a key decision point in urea injection control. When the conversion efficiency F remains stable or improves, the system confirms that the current urea injection correction strategy is effective, so the correction coefficient L is maintained unchanged and continues to be executed to optimize N2O and NOx emissions. However, once the conversion efficiency F is found to have decreased, the system immediately evaluates that the current correction may interfere with the normal conversion process of NOx, and then takes protective measures: automatically reset the urea injection correction coefficient L to 1, that is, cancel all urea amount adjustments based on the difficulty of N2O generation, and quickly restore the basic injection strategy to ensure that NOx emissions quickly return to compliance levels. This adjustment is not permanent, and the system will continue to monitor the conversion efficiency and N2O emissions to look for opportunities for recovery or improvement. If the monitoring data shows that the conversion efficiency has recovered or N2O emissions have decreased, it indicates that the environmental conditions or system status may have changed. At this time, the controller will re-evaluate whether it is appropriate to introduce urea injection correction to balance the needs of NOx conversion and N2O suppression to achieve more refined emission control.

[0142] Embodiment 2

[0143] Figure 3 : is a structural schematic diagram of a urea injection control system for a National VII diesel engine based on real-time parameter monitoring in Embodiment 2 of the present invention, such as Figure 3 As shown, embodiment 2 provides a urea injection control system for a National VII diesel engine based on real-time parameter monitoring, which is applied to a controller. The system includes: a first calculation module 301, a first monitoring module 302, a second calculation module 303, a dynamic adjustment module 304, and a second monitoring module 305. The first calculation module 301 is used to measure the NOx concentration in real time through the NOx sensor arranged at the inlet of the two-stage SCR, and inquire the NO2 proportion coefficient from the NO2 model in combination with the engine operation state to calculate the NO2 concentration. The first monitoring module 302 is used to monitor the temperature and NO2 concentration before the SCR in real time as input parameters of the N2O generation difficulty model. The second calculation module 303 is used to establish an N2O generation difficulty model based on temperature and NO2 concentration according to the N2O generation characteristics, and calculate the N2O generation difficulty coefficient of the two-stage SCR. The dynamic adjustment module 304 is used to dynamically adjust the first-stage urea injection amount according to the N2O generation difficulty coefficient. And the second monitoring module 305 is used to monitor the NOx conversion efficiency of the two-stage SCR.

[0144] In this embodiment, the first calculation module 301 includes: a first acquisition unit, a first monitoring unit, a query unit and a first calculation unit. The first acquisition unit is used to automatically acquire real-time NOx concentration data through NOx sensors arranged at the first-stage SCR inlet and the second-stage SCR inlet, which are respectively denoted as Q1 and Q2. The first monitoring unit is used to monitor the operating state of the engine in real time, including the engine speed and the circulating oil volume. The query unit is used to automatically query the corresponding NO2 proportion coefficient at this time from the pre-stored NO2 model according to the real-time acquired engine speed and the circulating oil volume, which are respectively denoted as R1 and R2. And the first calculation unit is used to automatically calculate the NO2 concentration at the first-stage SCR inlet and the second-stage SCR inlet using the measured NOx concentrations Q1 and Q2 and the queried NO2 proportion coefficients R1 and R2, which are respectively denoted as M1 and M2.

[0145] In this embodiment, the first monitoring module 302 includes: a second monitoring unit, a second acquisition unit, an integration unit and a third monitoring unit. The second monitoring unit is used to automatically monitor the temperature sensors arranged in front of the first-stage SCR and the second-stage SCR, and obtain exhaust temperature data in real time, which are recorded as T1 and T2 respectively. The second acquisition unit is used to obtain real-time NO2 concentration data from the NOx and NO2 concentration monitoring steps, namely M1 and M2. The integration unit is used to integrate the acquired exhaust temperature T1 and T2 and NO2 concentration M1 and M2 data, and automatically store them in the internal memory. The third monitoring unit is used to continuously monitor the changes in exhaust temperature and NO2 concentration, and update the stored data in real time as input parameters of the N2O generation difficulty model.

[0146] In this embodiment, the second calculation module 303 includes: an establishment unit, an input unit and a second calculation unit. The establishment unit is used to pre-establish a mathematical model describing the relationship between the difficulty of N2O generation and the exhaust temperature and NO2 concentration based on research data and experience. The input unit is used to automatically input the exhaust temperature T1 and T2 and NO2 concentrations M1 and M2 monitored in real time as input parameters into the N2O generation difficulty model. The second calculation unit is used to use the established mathematical model to automatically calculate the N2O generation difficulty coefficients of the first-stage SCR and the second-stage SCR according to the input exhaust temperature and NO2 concentration, which are recorded as K1 and K2 respectively. Among them, the smaller the difficulty coefficient, the easier it is to generate N2O at this time, and control is required, while the larger the difficulty coefficient, the greater the difficulty of generating N2O.

[0147] In this embodiment, the dynamic adjustment module 304 includes: a third acquisition unit, a first judgment unit, a third calculation unit and a dynamic adjustment unit. The third acquisition unit is used to automatically obtain the N2O generation difficulty coefficients K1 and K2 of the first-stage SCR and the second-stage SCR from the N2O generation difficulty model. The first judgment unit is used to determine the correction direction of urea injection based on the N2O generation difficulty coefficients K1 and K2. The third calculation unit is used to automatically calculate the correction coefficient L of urea injection according to the determined correction direction. The dynamic adjustment unit is used to apply the calculated correction coefficient L to the injection amount of the first-stage urea to dynamically adjust the injection amount of the first-stage urea.

[0148] In this embodiment, the second monitoring module 305 includes: a fourth acquisition unit, a fourth calculation unit, a second judgment unit and a correction unit. The fourth acquisition unit is used to automatically obtain real-time NOx concentration data from the NOx sensors arranged before and after the catalyst, which are recorded as N1 and N2 respectively. The fourth calculation unit is used to use the acquired NOx concentration data to automatically calculate the total NOx conversion efficiency F of the two-stage SCR according to the formula F=(N1-N2) / N1. The second judgment unit is used to compare the calculated conversion efficiency F with a preset threshold or historical data to determine whether the conversion efficiency has decreased. The correction unit is used to maintain the current urea injection correction coefficient L and continue to execute the correction strategy if the conversion efficiency F has not decreased; if the conversion efficiency F has decreased, the urea injection correction coefficient L is automatically adjusted to 1 and the correction is cancelled.

[0149] The various variations and specific examples of the urea injection control method for a National VII diesel engine based on real-time parameter monitoring provided in Example 1 are also applicable to the urea injection control system for a National VII diesel engine based on real-time parameter monitoring provided in this embodiment. Through the above detailed description of a urea injection control method for a National VII diesel engine based on real-time parameter monitoring, those skilled in the art can clearly know the implementation method of a urea injection control system for a National VII diesel engine based on real-time parameter monitoring in this embodiment, so for the sake of brevity of the specification, it will not be described in detail here.

[0150] Figure 5 FIG. 1 is a schematic diagram of the working logic flow of a urea injection control method for a National VII diesel engine based on real-time parameter monitoring according to a specific embodiment of the present invention. Figure 5 As shown, in a specific embodiment of the present invention, the working logic of the present invention is as follows:

[0151] S1, through the NOx sensors arranged at the first and second stage SCR inlet, the NOx concentrations Q1 and Q2 at this position are accurately measured. According to the real-time engine operating speed and circulating oil volume, the NO2 proportion coefficients R1 and R2 at this time are queried from the NO2 model, and the NO2 concentration at the first stage SCR inlet M1 = Q1*R1, and the NO2 concentration at the second stage SCR inlet M2 = Q2*R2.

[0152] S2, real-time monitoring of parameters affecting N2O emissions. The temperatures before the first and second stage SCR are tested and output by temperature sensors arranged at this position, and the NO2 concentration is calculated and output by S1.

[0153] S3, according to research: SCR and ASC will generate N2O rapidly at a temperature of 200℃, reaching the highest generation rate at around 250℃, and less N2O will be generated after exceeding 300℃; the greater the NO2 concentration in the exhaust gas, the more N2O will be generated. According to the above characteristics of N2O generation, a N2O generation difficulty model is established based on the temperature and NO2 concentration that affect N2O emissions. Through real-time exhaust temperature and NO2 concentration, the model calculates the difficulty coefficient K1 of the first-stage SCR generating N2O and the difficulty coefficient K2 of the second-stage SCR generating N2O. The smaller the coefficient, it means that N2O is easily generated at this time and needs to be controlled.

[0154] S4, establish a correction coefficient L for the first-stage urea injection based on the difficulty coefficient K1 of the first-stage SCR to generate N2O and the difficulty coefficient K2 of the second-stage SCR to generate N2O. 1) If K1 is small and K2 is large, the first-stage urea injection correction coefficient L less than 1 is output. After the originally set first-stage urea injection amount is multiplied by L, the injection reduction will be executed. If there is less urea, the generated N2O will be reduced. At the same time, since the first-stage SCR urea injection is less, the converted NOx is also reduced, and the NOx reaching the second-stage SCR will also increase. At this time, the second stage measures the increase in NOx concentration through the NOx sensor installed at this position. The urea injection amount can be increased according to the model to convert the increased NOx, and the final output NOx remains unchanged. Although the second-stage urea injection amount has increased, since it is not easy to generate N2O under the current conditions, the N2O generated by the second-stage SCR will not increase significantly, so the total N2O can be significantly reduced. 2) If K1 is larger and K2 is smaller, the first-stage urea injection correction coefficient L is outputted to be greater than 1, the first-stage urea injection amount increases, more NOx is converted, but N2O does not increase significantly. The second stage reduces the urea injection amount according to the NOx concentration, and N2O generation is reduced.

[0155] S5, the NOx sensors before and after the catalyst measure the NOx concentrations N1 and N2, and the total conversion efficiency of the two-stage SCR is F = (N1-N2) / N1. If the SCR conversion efficiency F does not decrease, the correction of the first-stage urea injection is maintained.

[0156] S6: If the SCR conversion efficiency F decreases after adjusting the first-stage urea injection, there is a risk of increasing NOx emissions, indicating that the current conditions are not suitable for urea injection correction to reduce N2O. The correction coefficient L of the first-stage urea injection becomes 1, and the correction is canceled.

[0157] Embodiment 3

[0158] Figure 4 is a schematic diagram of the structure of an electronic device in Embodiment 3 of the present invention, such as Figure 4 As shown, the third embodiment further provides an electronic device 400 , which may include: a processor 401 and a memory 402 .

[0159] The memory 402 is used to store programs. The memory 402 may include a volatile memory, such as a random access memory (RAM), such as a static random access memory (SRAM), a double data rate synchronous dynamic random access memory (DDR SDRAM), etc. The memory may also include a non-volatile memory, such as a flash memory. The memory 402 is used to store computer programs (such as applications, function modules, etc. for implementing the above method), computer instructions, etc. The above computer programs, computer instructions, etc. may be partitioned and stored in one or more memories 402. And the above computer programs, computer instructions, data, etc. may be called by the processor 401.

[0160] The above-mentioned computer programs, computer instructions, etc. may be stored in partitions in one or more memories 402 . And the above-mentioned computer programs, computer instructions, etc. may be called by the processor 401 .

[0161] The processor 401 is used to execute the computer program stored in the memory 402 to implement each step of the method involved in the above embodiment.

[0162] For details, please refer to the relevant description in the previous method embodiment.

[0163] The processor 401 and the memory 402 may be independent structures or integrated structures. When the processor 401 and the memory 402 are independent structures, the memory 402 and the processor 401 may be coupled and connected via a bus 403 .

[0164] The electronic device of this embodiment can execute the technical solution in the above method, and its specific implementation process and technical principle are the same, which will not be repeated here.

[0165] Embodiment 4

[0166] Embodiment 4 further provides a computer-readable storage medium, including a computer program and instructions. When the computer program or instructions are executed on a computer, the computer executes a control method for preventing urea nozzle crystallization blockage according to any embodiment of the present invention.

[0167] Computer-readable storage media include: USB flash drives, mobile hard disks, ROM, RAM, magnetic disks, or optical disks, and other media that can store program codes.

[0168] This embodiment also provides a computer program product, which includes: a computer program, which is stored in a readable storage medium. At least one processor of an electronic device can read the computer program from the readable storage medium, and at least one processor executes the computer program so that the electronic device executes the solution provided by any of the above embodiments.

[0169] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the disclosure of the present invention can be performed in parallel, sequentially or in different orders, as long as the desired results of the technical solution disclosed in the present invention can be achieved, and this document does not limit this.

[0170] Note that the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A urea injection control method for a National VII diesel engine based on real-time parameter monitoring, applied in a controller, characterized in that: The method comprises: Step S100, measuring the NOx concentration in real time by using the NOx sensors arranged at the inlets of the two-stage SCR, and querying the NO2 proportion coefficient from the NO2 model in combination with the engine running state to calculate the NO2 concentration; Step S200, real-time monitoring of the temperature and NO2 concentration before the SCR as input parameters of the N2O generation difficulty model; Step S300, according to the N2O generation characteristics, establish a N2O generation difficulty model based on temperature and NO2 concentration, and calculate the N2O generation difficulty coefficient of the two-stage SCR; Step S400, dynamically adjusting the first-stage urea injection amount according to the N2O generation difficulty coefficient; Step S500, monitoring the NOx conversion efficiency of the two-stage SCR.

2. The urea injection control method for a National VII diesel engine based on real-time parameter monitoring as claimed in claim 1, characterized in that: The step S100 includes: Step S101, automatically acquiring real-time NOx concentration data through NOx sensors arranged at the inlet of the first-stage SCR and the inlet of the second-stage SCR, which are respectively denoted as Q1 and Q2; Step S102, real-time monitoring of the engine operating status, including engine speed and circulating oil volume; Step S103, according to the real-time acquired engine speed and circulating oil volume, automatically query the corresponding NO2 proportion coefficient at this time from the pre-stored NO2 model, and record them as R1 and R2 respectively; Step S104, using the measured NOx concentrations Q1 and Q2 and the queried NO2 proportion coefficients R1 and R2, the NO2 concentrations at the first-stage SCR inlet and the second-stage SCR inlet are automatically calculated and recorded as M1 and M2 respectively.

3. The urea injection control method for a National VII diesel engine based on real-time parameter monitoring as claimed in claim 1, characterized in that: The step S200 includes: Step S201, automatically monitoring the temperature sensors arranged before the first stage SCR and the second stage SCR, and obtaining exhaust temperature data in real time, which are recorded as T1 and T2 respectively; Step S202, obtaining real-time NO2 concentration data, namely M1 and M2, from the NOx and NO2 concentration monitoring step; Step S203, integrating the acquired exhaust temperature T1 and T2 and NO2 concentration M1 and M2 data, and automatically storing them in the internal memory; Step S204, continuously monitor the changes in exhaust temperature and NO2 concentration, and update the stored data in real time as input parameters of the N2O generation difficulty model.

4. The urea injection control method for a National VII diesel engine based on real-time parameter monitoring as claimed in claim 1, characterized in that: The step S300 includes: Step S301, based on research data and experience, a mathematical model is pre-established to describe the relationship between the difficulty of N2O generation and the exhaust temperature and NO2 concentration; Step S302, automatically taking the exhaust gas temperatures T1 and T2 and NO2 concentrations M1 and M2 monitored in real time as input parameters and passing them into the N2O generation difficulty model; Step S303, using the established mathematical model, according to the input exhaust temperature and NO2 concentration, automatically calculate the N2O generation difficulty coefficients of the first-stage SCR and the second-stage SCR, which are recorded as K1 and K2 respectively; Among them, the smaller the difficulty coefficient, the easier it is to generate N2O, which needs to be controlled, and the larger the difficulty coefficient, the more difficult it is to generate N2O.

5. The urea injection control method for a National VII diesel engine based on real-time parameter monitoring as claimed in claim 1, characterized in that: The step S400 includes: Step S401, automatically obtaining N2O generation difficulty coefficients K1 and K2 of the first-stage SCR and the second-stage SCR from the N2O generation difficulty model; Step S402, determining the correction direction of urea injection based on the difficulty coefficients K1 and K2 generated by N2O; Step S403, automatically calculating the correction coefficient L of urea injection according to the determined correction direction; Step S404: applying the calculated correction coefficient L to the injection amount of the first-stage urea to dynamically adjust the injection amount of the first-stage urea.

6. The urea injection control method for a National VII diesel engine based on real-time parameter monitoring as claimed in claim 1, characterized in that: The step S500 includes: Step S501, automatically obtaining real-time NOx concentration data from NOx sensors arranged before and after the catalyst, which are recorded as N1 and N2 respectively; Step S502, using the acquired NOx concentration data, according to the formula F=(N1-N2) / N1, automatically calculate the total NOx conversion efficiency F of the two-stage SCR; Step S503, comparing the calculated conversion efficiency F with a preset threshold or historical data to determine whether the conversion efficiency has decreased; Step S504: if the conversion efficiency F does not decrease, the current urea injection correction coefficient L is maintained and the correction strategy is continued to be executed; if the conversion efficiency F decreases, the urea injection correction coefficient L is automatically adjusted to 1 and the correction is canceled.

7. A urea injection control system for a National VII diesel engine based on real-time parameter monitoring, applied to a controller, characterized in that: The system comprises: The first calculation module is used to measure the NOx concentration in real time through the NOx sensor arranged at the inlet of the two-stage SCR, and inquire the NO2 proportion coefficient from the NO2 model in combination with the engine operation state to calculate the NO2 concentration; The first monitoring module is used to monitor the temperature and NO2 concentration before the SCR in real time as input parameters of the N2O generation difficulty model; The second calculation module is used to establish a N2O generation difficulty model based on temperature and NO2 concentration according to the N2O generation characteristics, and calculate the N2O generation difficulty coefficient of the two-stage SCR; A dynamic adjustment module, for dynamically adjusting the first-stage urea injection amount according to the N2O generation difficulty coefficient; and The second monitoring module is used to monitor the NOx conversion efficiency of the two-stage SCR.

8. The urea injection control system for a National VII diesel engine based on real-time parameter monitoring as claimed in claim 7, characterized in that: The first calculation module includes: A first acquisition unit is used to automatically acquire real-time NOx concentration data through NOx sensors arranged at the inlet of the first-stage SCR and the inlet of the second-stage SCR, which are respectively denoted as Q1 and Q2; A first monitoring unit, for real-time monitoring of the operating status of the engine, including engine speed and circulating oil volume; A query unit, used for automatically querying the corresponding NO2 proportion coefficient at this time from the pre-stored NO2 model according to the engine speed and the circulating oil volume obtained in real time, which are recorded as R1 and R2 respectively; The first calculation unit is used to automatically calculate the NO2 concentrations at the first-stage SCR inlet and the second-stage SCR inlet by using the measured NOx concentrations Q1 and Q2 and the queried NO2 proportion coefficients R1 and R2, which are recorded as M1 and M2 respectively.

9. An electronic device, characterized in that: include: at least one processor; as well as a memory communicatively coupled to the at least one processor; Wherein, the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor can execute the urea injection control method for the National VII diesel engine based on real-time parameter monitoring as described in any one of claims 1-6.

10. A computer-readable storage medium, characterized in that: It comprises a computer program and instructions. When the computer program or the instructions are run on a computer, the computer executes the urea injection control method based on real-time parameter monitoring for a National VII diesel engine as described in any one of claims 1-6.

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