Novel NH3 leakage detection system applied to diesel engine aftertreatment system
By using SCR inlet and outlet NOx sensors and temperature sensors in the diesel engine aftertreatment system, combined with the ECU controller, and calculating the NOx efficiency difference, effective detection of NH3 leakage is achieved, solving the accuracy and cost issues of NH3 leakage supervision.
Patent Information
- Application Number
- CN202422607893.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-28
- Publication Date
- 2025-09-26
- Estimated Expiration
- 2034-10-28
AI Technical Summary
NH3 leak detection in existing diesel engine aftertreatment systems relies on expensive NH3 sensors, resulting in poor controller robustness and inaccurate feedback correction coefficients, which leads to excessive urea injection and ineffective NH3 leakage monitoring.
Using SCR inlet and outlet NOx sensors, combined with temperature sensors and ECU controllers, the difference between actual NOx efficiency and model efficiency is calculated to determine NH3 leakage, and the after-treatment system's built-in components are used to achieve NH3 supervision.
No additional NH3 sensor is required, and NH3 leak detection can be achieved through built-in components, which improves the robustness of the system and the accuracy of NH3 supervision and reduces detection costs.
Smart Images
Figure CN223387402U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of engine exhaust treatment, in particular to a novel NH3 leakage detection system applied to a diesel engine after-treatment system. Background Art
[0002] For off-engine emission reduction technologies, the primary after-treatment technology for China VI diesel vehicles utilizes DOC+DPF+SCR+ASC. This technology reduces NOx emissions by injecting precisely metered urea into an after-treatment catalyst via a urea pump through a urea nozzle. Urea is hydrolyzed into ammonia and water in the hot exhaust. The SCR catalyst then reacts with the ammonia and NOx in the exhaust, producing harmless nitrogen that is discharged out of the engine, achieving NOx reduction. The calculation of the required NH3 injection amount for a diesel engine's SCR system is subject to system control errors and deviations. These factors, such as fluctuations in raw engine emissions, instability in the urea injection system, discrepancies between actual and calculated values in the feedback control system, flaws in the urea metering calibration strategy and improper parameter settings, aging of related physical components, and degradation of the SCR catalyst's performance, can degrade the accuracy and stability of the SCR system's NOx and NH3 emissions control, potentially leading to excessive NH3 emissions in the exhaust.
[0003] Due to the high cost of NH3 sensors, NOx sensors are currently the primary means of feedback monitoring for SCR aftertreatment in commercial vehicle diesel engines. However, the lateral sensitivity of NOx sensors to NH3 can reduce the robustness of NOx controllers, leading to inaccurate calculation of feedback correction coefficients, excessive urea injection, and consequently NH3 leakage.
[0004] Therefore, it is necessary to provide a new type of NH3 leakage detection system applied to diesel engine after-treatment system to solve the above technical problems. Utility Model Content
[0005] The technical problem solved by the utility model is to provide a novel NH3 leakage detection system for diesel engine after-treatment system, which does not require additional NH3 sensors and only relies on NOx and other components of the after-treatment system to monitor the pollutant NH3.
[0006] To solve the above technical problems, the present invention provides a novel NH3 leak detection system for a diesel engine aftertreatment system, comprising: an SCR inlet NOx sensor and an SCR outlet NOx sensor, wherein the SCR inlet NOx sensor is installed at one end of an exhaust branch pipe connected to the engine, and the other end of the exhaust branch pipe is connected to an SCR catalyst, and an SCR inlet temperature sensor is installed at the connection between the exhaust branch pipe and the SCR catalyst; the SCR outlet NOx sensor is installed at the outlet of the SCR catalyst, and a urea aqueous solution nozzle is installed at the inlet of the SCR catalyst, and the urea aqueous solution nozzle is connected to a urea supply pump; the SCR inlet NOx sensor and the SCR outlet NOx sensor are electrically connected to a NOx actual efficiency calculation module, the SCR inlet temperature sensor and the SCR inlet NOx sensor are electrically connected to an SCR physicochemical power module, the SCR physicochemical power module is electrically connected to a NOx model efficiency calculation module, and both the NOx actual efficiency calculation module and the NOx model efficiency calculation module are electrically connected to a judgment module.
[0007] Preferably, the urea supply pump is electrically connected to the ECU controller, a main control unit CPU is provided inside the ECU controller, and the main control unit CPU is electrically connected to the judgment module.
[0008] Preferably, the engine is connected to an engine operating condition information module, and the engine operating condition information module is electrically connected to an SCR physical and chemical power module, and the SCR physical and chemical power module calculates the NOx model concentration value at the SCR outlet.
[0009] Preferably, in the NOx actual efficiency calculation module, the calculation formula of the NOx actual efficiency is (SCR inlet NOx sensor value-SCR outlet NOx sensor value) / SCR inlet NOx sensor value.
[0010] Preferably, in the NOx model efficiency calculation module, the calculation formula of the NOx model efficiency is (SCR inlet NOx sensor value-SCR outlet NOx model concentration value) / SCR inlet NOx sensor value.
[0011] Compared with related technologies, the novel NH3 leak detection system for diesel engine aftertreatment system provided by the present invention has the following beneficial effects:
[0012] The utility model provides a novel NH3 leakage detection system for a diesel engine after-treatment system. During the exhaust treatment process, the NOx actual efficiency calculation module and the NOx model efficiency calculation module upload the calculated NOx actual efficiency and NOx model efficiency to the judgment module. The main control unit CPU runs the calculation data inside the judgment module. When the NOx model efficiency exceeds 95% and the difference with the NOx actual efficiency is greater than 20%, the judgment module runs and actively triggers the NH3 leakage detection function module. After the NH3 leakage detection function is activated, the urea supply pump will first stop running and no longer spray urea aqueous solution. The SCR inlet NOx sensor and the SCR outlet NOx sensor monitor the NOx value in the exhaust gas, and the integral difference between the two sensors is X= The SCR inlet NOx sensor value minus the SCR outlet NOx sensor value. The SCR inlet temperature sensor monitors exhaust gas temperature. The main control unit CPU calculates the NH3 storage value Y within the SCR catalyst based on the temperature and the volume of previously injected urea-water solution. The ratio between X and Y is calculated, and a predetermined threshold Z is set based on the difference between X and Y. If NH3 leakage occurs, the actual Y value is greater than the Y value calculated by the main control unit CPU, and NH3 reacts catalytically with NOx in the exhaust gas, increasing the X value. The judgment module operates, and if the difference between X and Y is greater than the predetermined threshold Z, it is assumed that there is no NH3 leakage; otherwise, it is assumed that there is NH3 leakage. This eliminates the need for an additional NH3 sensor, relying solely on the NOx and other components of the aftertreatment system to monitor the pollutant NH3. BRIEF DESCRIPTION OF THE DRAWINGS
[0013] Figure 1 A schematic structural diagram of a preferred embodiment of a novel NH3 leakage detection system for a diesel engine after-treatment system provided by the present invention;
[0014] Figure 2 This is a schematic diagram briefly illustrating the software logic in this utility model;
[0015] Figure 3 This is a schematic diagram of the circuit structure of the utility model.
[0016] Numbers in the figure: 1. ECU controller, 2. Engine, 3. SCR inlet NOx sensor, 4. Urea aqueous solution nozzle, 5. SCR inlet temperature sensor, 6. SCR catalyst, 7. SCR outlet NOx sensor, 8. Main control unit CPU, 9. Urea supply pump, 10. Exhaust branch pipe, 11. NOx actual efficiency calculation module, 12. NOx model efficiency calculation module, 13. Judgment module. DETAILED DESCRIPTION
[0017] The present invention will be further described below with reference to the accompanying drawings and implementation examples.
[0018] See also Figures 1 to 3 , Figure 1 A schematic structural diagram of a preferred embodiment of a novel NH3 leakage detection system for a diesel engine after-treatment system provided by the present invention; Figure 2 This is a schematic diagram briefly illustrating the software logic in this utility model; Figure 3 This is a schematic diagram of the circuit structure of the utility model. The novel NH3 leak detection system for a diesel engine aftertreatment system includes: an SCR inlet NOx sensor 3 and an SCR outlet NOx sensor 7. The SCR inlet NOx sensor 3 is mounted at one end of an exhaust branch pipe 10 connected to the engine 2, and the other end of the exhaust branch pipe 10 is connected to an SCR catalyst 6. An SCR inlet temperature sensor 5 is mounted at the connection between the exhaust branch pipe 10 and the SCR catalyst 6. The SCR outlet NOx sensor 7 is mounted at the outlet of the SCR catalyst 6, and a urea aqueous solution nozzle 4 is mounted at the inlet of the SCR catalyst 6, and the urea aqueous solution nozzle 4 is connected to a urea supply pump 9. The SCR inlet NOx sensor 3 and the SCR outlet NOx sensor 7 are electrically connected to a NOx actual efficiency calculation module 11. The SCR inlet temperature sensor 5 and the SCR inlet NOx sensor 3 are electrically connected to an SCR physical and chemical power module. The SCR physical and chemical power module is electrically connected to a NOx model efficiency calculation module 12. Both the NOx actual efficiency calculation module 11 and the NOx model efficiency calculation module 12 are electrically connected to a judgment module 13.
[0019] The urea supply pump 9 is electrically connected to the ECU controller 1, so that the ECU controller 1 can control the operation of the urea supply pump 9 and deliver an appropriate amount of urea aqueous solution to the urea aqueous solution nozzle 4. A main control unit CPU 8 is provided inside the ECU controller 1, and the main control unit CPU is electrically connected to the judgment module 13, so that the main control unit CPU can run and calculate the data inside the judgment module 13 to determine whether there is NH3 leakage.
[0020] The engine 2 is connected to the engine operating condition information module, and the engine operating condition information module is electrically connected to the SCR physical and chemical power module. The SCR physical and chemical power module calculates the NOx model concentration value at the SCR outlet, thereby facilitating the calculation of the NOx model efficiency.
[0021] In the NOx actual efficiency calculation module 11 , the calculation formula of the NOx actual efficiency is (SCR inlet NOx sensor value−SCR outlet NOx sensor value) / SCR inlet NOx sensor value.
[0022] In the NOx model efficiency calculation module 12 , the calculation formula of the NOx model efficiency is (SCR inlet NOx sensor value−SCR outlet NOx model concentration value) / SCR inlet NOx sensor value.
[0023] When the engine 2 is running, the engine operating condition information module constantly monitors various data during the operation of the engine 2 and uploads the data to the SCR physical and chemical power module for processing. The engine generates exhaust gas, which flows in the exhaust branch pipe 10. The SCR inlet temperature sensor 5 monitors the exhaust gas temperature. When the temperature exceeds 250 degrees Celsius, the SCR inlet NOx sensor 3 is responsible for sampling the original NOx concentration value in the engine exhaust gas in units of PPM. The SCR inlet NOx sensor 3 and the SCR inlet temperature sensor 5 upload the information to the main control unit CPU 8. The main control unit CPU 8 calculates the data to calculate the required volume of urea aqueous solution and uploads the information to the ECU controller 1. The ECU controller 1 controls the operation of the urea supply pump 9 to spray an appropriate amount of urea aqueous solution through the urea aqueous solution nozzle 4 into the interior of the SCR catalyst 6 to treat the exhaust gas. The treated exhaust gas is discharged from the SCR catalyst 6. At this time, the SCR outlet NOx sensor 7 is responsible for sampling the NOx value in the exhaust gas after conversion by the SCR catalyst in units of PPM.
[0024] The data monitored by the SCR inlet NOx sensor 3 and the SCR outlet NOx sensor 7 are uploaded to the NOx actual efficiency calculation module 11. The NOx actual efficiency calculation module 11 runs and calculates the NOx actual efficiency according to the calculation formula (SCR inlet NOx sensor value-SCR outlet NOx sensor value) / SCR inlet NOx sensor value.
[0025] The SCR inlet NOx sensor 3, the SCR inlet temperature sensor 5 and the engine operating condition information module upload the monitored data to the SCR physical and chemical power module, and the SCR physical and chemical power module calculates the SCR outlet NOx model concentration value based on the data. The NOx model efficiency calculation module 12 transports the data and calculates the NOx model efficiency according to the formula (SCR inlet NOx sensor value-SCR outlet NOx model concentration value) / SCR inlet NOx sensor value.
[0026] The NOx actual efficiency calculation module 11 and the NOx model efficiency calculation module 12 upload the calculated NOx actual efficiency and NOx model efficiency to the judgment module 13. The main control unit CPU runs the calculation data in the judgment module 13. When the NOx model efficiency exceeds 95% and the difference with the NOx actual efficiency is greater than 20%, the judgment module 13 runs to actively trigger the NH3 leakage detection function module. After the NH3 leakage detection function is activated, the urea supply pump 9 will be stopped and the urea aqueous solution will no longer be sprayed. The SCR inlet NOx sensor 3 and the SCR outlet NOx sensor 7 monitor the NOx value in the exhaust gas, and the integral difference between the two sensors X = SCR inlet NOx sensor value - SCR outlet NOx sensor value. The SCR inlet NOx sensor 3 and the SCR outlet NOx sensor 7 monitor the NOx value in the exhaust gas, and the integral difference between the two sensors X = SCR inlet NOx sensor value - SCR outlet NOx sensor value. The exhaust gas temperature is monitored by the temperature sensor 5. The main control unit CPU calculates the NH3 storage value Y within the SCR catalyst 6 based on the temperature and the volume of urea aqueous solution previously injected. The ratio between X and Y is calculated, and a predetermined threshold value Z is set based on the difference between X and Y. If NH3 leakage occurs, the actual value Y is greater than the value Y calculated by the main control unit CPU, and a catalytic reaction occurs between NH3 and NOx in the exhaust gas, causing the value X to increase. The judgment module 13 operates. If the difference between X and Y is greater than the predetermined threshold value Z, it is assumed that no NH3 leakage exists, and the function status word is set to 1. Otherwise, it is assumed that NH3 leakage exists, and the function status word is set to 2. If the actual NOx efficiency drops significantly during the urea injection stop and reaches the critical efficiency threshold, the urea supply pump 9 immediately resumes injection of urea aqueous solution and sets the status word to 1.
[0027] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made by using the contents of the description and drawings of the present invention, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.
Claims
1. A new type of NH3 leak detection system for diesel engine after-treatment system, characterized by: include: An SCR inlet NOx sensor (3) and an SCR outlet NOx sensor (7), wherein the SCR inlet NOx sensor (3) is installed at one end of an exhaust branch pipe (10) connected to an engine (2), and the other end of the exhaust branch pipe (10) is connected to an SCR catalyst (6); and an SCR inlet temperature sensor (5) is installed at the connection between the exhaust branch pipe (10) and the SCR catalyst (6); An SCR outlet NOx sensor (7) is installed at the air outlet of the SCR catalyst (6), a urea aqueous solution nozzle (4) is installed at the air inlet of the SCR catalyst (6), and the urea aqueous solution nozzle (4) is connected to a urea supply pump (9); The SCR inlet NOx sensor (3) and the SCR outlet NOx sensor (7) are electrically connected to a NOx actual efficiency calculation module (11), the SCR inlet temperature sensor (5) and the SCR inlet NOx sensor (3) are electrically connected to an SCR physical and chemical power module, the SCR physical and chemical power module is electrically connected to a NOx model efficiency calculation module (12), and both the NOx actual efficiency calculation module (11) and the NOx model efficiency calculation module (12) are electrically connected to a judgment module (13).
2. The novel NH3 leakage detection system for diesel engine after-treatment system according to claim 1 is characterized in that: The urea supply pump (9) is electrically connected to the ECU controller (1), a main control unit CPU (8) is provided inside the ECU controller (1), and the main control unit CPU is electrically connected to the judgment module (13).
3. The novel NH3 leakage detection system for diesel engine after-treatment system according to claim 1 is characterized in that: The engine (2) is connected to an engine operating condition information module, and the engine operating condition information module is electrically connected to an SCR physical and chemical power module, and the SCR physical and chemical power module calculates the NOx model concentration value at the SCR outlet.