Vehicle-mounted tail gas purification and emission control system

Abstract

The invention relates to the technical field of automobile tail gas treatment, in particular to a vehicle-mounted tail gas purification and emission control system which comprises a multi-stage purification module, a real-time data acquisition module, an intelligent control unit and a regeneration execution module which are sequentially connected in series. The data acquisition module acquires tail gas temperature, pressure, pollutant concentration and engine working condition parameters and transmits the parameters to the intelligent control unit; and the intelligent control unit outputs regulation and control signals to the multi-stage purification module and the regeneration execution module based on a preset control strategy according to the working condition data, so that cooperative control of low-temperature catalytic preheating, particulate trapping regeneration and selective catalytic reduction precise liquid spraying is realized. The system can dynamically adapt to different working conditions of the engine, improves the tail gas purification efficiency, reduces the fuel consumption in the regeneration process, reduces the influence of tail gas emission on the environment, and is suitable for various vehicle types such as gasoline cars and diesel cars.

Description

Technical Field

[0001] This invention relates to the field of automotive exhaust treatment technology, specifically to an on-board exhaust purification and emission control system. Background Technology

[0002] With the continuous growth of global car ownership, vehicle exhaust emissions have become one of the main sources of air pollution. To control exhaust pollution, countries have successively introduced strict emission standards, such as my country's China VI emission standard, which significantly lowers the limits for pollutants in exhaust gases compared to the China V standard. This places higher demands on vehicle exhaust purification technology.

[0003] Currently, vehicle exhaust purification devices mainly include three-way catalytic converters, disposable particulate filters (DPF), and selective catalytic reduction systems (SCR). The three-way catalytic converter is the core component for gasoline vehicle exhaust purification. It uses precious metal catalysts such as platinum, palladium, and rhodium to oxidize carbon monoxide and hydrocarbons into carbon dioxide and water, and reduce nitrogen oxides into nitrogen. However, the catalytic activity of the three-way catalytic converter is quite sensitive to temperature. During engine cold starts, the exhaust temperature is typically below 200°C, and the catalyst cannot reach its optimal activity temperature, resulting in a purification efficiency of less than 30% in the initial cold start phase. A large amount of unpurified pollutants are directly emitted into the atmosphere. Statistics show that during urban driving conditions, cold start emissions account for 40%-60% of total emissions, making this a key bottleneck restricting the effectiveness of gasoline vehicle exhaust purification.

[0004] For diesel vehicles, the diesel particulate filter (DPF) is the primary device for controlling particulate emissions. The DPF captures particulate matter in the exhaust gas through a porous ceramic filter. However, with increased use, particulate matter gradually accumulates on the filter, leading to increased exhaust back pressure and affecting engine power performance and fuel economy. To address this issue, existing DPFs typically employ two methods: passive regeneration and active regeneration. Passive regeneration relies on the exhaust gas's own temperature to burn particulate matter, suitable for long-distance high-speed driving. However, in congested urban conditions, the exhaust gas temperature is lower, making passive regeneration difficult and requiring active regeneration. Current active regeneration methods often inject fuel into the exhaust system, using fuel combustion to raise the internal temperature of the DPF to the particulate ignition point (approximately 550°C). However, this method suffers from high fuel consumption (0.5-1L of fuel per regeneration cycle) and low temperature control accuracy. If the temperature is too high (above 700°C), the DPF filter may crack, shortening its lifespan; if the temperature is insufficient, particulate matter cannot be completely burned, resulting in poor regeneration.

[0005] Selective catalytic reduction (SCR) is a core technology for controlling nitrogen oxide emissions in diesel vehicles. It reduces nitrogen oxides to nitrogen and water by injecting urea solution, under the action of a catalyst. Current SCR systems primarily control the urea injection volume based on preset operating parameters such as engine speed and load, which is an open-loop control. However, in actual driving, engine conditions are complex and variable, such as acceleration, deceleration, and idling, leading to drastic changes in exhaust gas flow, temperature, and nitrogen oxide concentration. The preset injection volume cannot accurately match actual needs. When the urea injection volume is insufficient, nitrogen oxide reduction is incomplete, resulting in excessive emission concentrations; when the injection volume is excessive, unreacted urea decomposes into ammonia, causing secondary pollution and increasing urea usage costs.

[0006] Furthermore, existing vehicle exhaust purification systems mostly operate independently of their components, lacking a coordinated control mechanism. For example, the high-temperature exhaust gas generated during DPF regeneration can affect the activity of the SCR catalyst, and changes in the urea injection volume of the SCR system may also interfere with the DPF regeneration effect. At the same time, existing systems have relatively simple monitoring mechanisms for their own operational status, only able to detect some faults through the vehicle's OBD system. They cannot monitor key parameters such as pollutant purification efficiency and DPF clogging level in real time, making it difficult for users to understand the system's operating status in a timely manner. Insufficient maintenance can easily lead to equipment damage or emissions exceeding standards.

[0007] With the continuous upgrading of emission standards, existing exhaust gas purification technologies are no longer able to meet actual needs. There is an urgent need to develop an on-board exhaust gas purification and emission control system that can achieve multi-component coordinated control, adapt to complex working conditions, improve purification efficiency, and reduce energy consumption. Summary of the Invention

[0008] The purpose of this invention is to overcome the problems of low-temperature purification efficiency, easy clogging and high regeneration energy consumption of DPF, inaccurate SCR urea injection control, and lack of coordinated control of multiple components in existing vehicle exhaust gas purification devices. The invention provides a vehicle exhaust gas purification and emission control system that realizes intelligent and dynamic control of the exhaust gas purification process, improves pollutant purification efficiency, reduces operating energy consumption, and extends equipment service life.

[0009] The technical solution adopted by this invention to solve its technical problem is: an on-board exhaust gas purification and emission control system, comprising: The multi-stage purification module is composed of a low-temperature catalytic component, a particulate trap component, and a selective catalytic reduction component connected in series along the exhaust gas flow direction. The low-temperature catalytic component is used for the preliminary purification of carbon monoxide and hydrocarbons in the exhaust gas during the engine cold start stage. The particulate trap component is used to capture particulate matter in the exhaust gas. The selective catalytic reduction component is used to reduce nitrogen oxides in the exhaust gas. The data acquisition module includes a first temperature sensor, a first pressure sensor, and a hydrocarbon concentration sensor located at the inlet of the multi-stage purification module; a second temperature sensor and a particulate matter concentration sensor located between the low-temperature catalytic component and the particulate matter collection component; a third temperature sensor and a second pressure sensor located between the particulate matter collection component and the selective catalytic reduction component; and a speed sensor and a load sensor that are communicatively connected to the engine ECU. The intelligent control unit is electrically connected to the data acquisition module and the multi-stage purification module respectively. The intelligent control unit stores a purification control strategy based on engine operating conditions. It can receive parameter signals transmitted by the data acquisition module, analyze and process them, and output a first control signal to the preheating unit of the low-temperature catalytic component and a second control signal to the urea injection device of the selective catalytic reduction component. The regeneration execution module is electrically connected to the intelligent control unit. The regeneration execution module includes an electric heating device and a fuel injection auxiliary device disposed at the inlet end of the particulate collection component. It can receive the third control signal output by the intelligent control unit to realize the active regeneration of the particulate collection component. The intelligent control unit determines whether to start the regeneration execution module by comparing the pressure difference between the inlet and outlet of the particulate collection component with a preset threshold, and adjusts the power of the electric heating device and the fuel injection quantity according to the signal of the second temperature sensor during the regeneration process.

[0010] Specifically, the carrier of the low-temperature catalytic component is cordierite honeycomb ceramic, and the surface of the carrier is coated with a palladium-rhodium composite catalyst. The preheating unit is a nickel-chromium alloy heating wire wound around the outside of the carrier, and the power adjustment range of the heating wire is 500W-1500W.

[0011] Specifically, the filter body of the particle collection component is a porous silicon carbide ceramic with a porosity of 55%-65%. The filter body has a pressure detection channel distributed along the axial direction inside, and the second pressure sensor collects the internal pressure of the filter body through this channel.

[0012] Specifically, the catalyst of the selective catalytic reduction component is a vanadium-tungsten-titanium composite oxide, and the urea injection device includes a urea tank, an electromagnetic injection valve, and an injection controller. The injection controller atomizes the urea solution and injects it into the exhaust gas passage according to the second control signal of the intelligent control unit. The urea injection quantity is positively correlated with the engine speed and load.

[0013] Specifically, the control strategy of the intelligent control unit includes a cold start phase strategy, a normal driving phase strategy, and a regeneration phase strategy. In the cold start phase, when the value detected by the first temperature sensor is below 200°C, a first control signal is output to make the preheating unit operate at maximum power until the value detected by the second temperature sensor reaches 250°C. In the normal driving phase, the urea injection volume is dynamically adjusted according to the speed and load signals. In the regeneration phase, when the pressure difference is greater than 15 kPa, the regeneration execution module is activated to raise the internal temperature of the particulate collection component to 550°C-600°C and maintain it for 10-15 minutes.

[0014] Specifically, the electric heating device of the regeneration execution module uses PWM pulse width modulation to adjust the power, and the injection time of the fuel injection auxiliary device is synchronized with the engine exhaust stroke, with a single injection amount of 5-10mg.

[0015] Specifically, the data acquisition module also includes a nitrogen oxide concentration sensor located at the outlet of the selective catalytic reduction component. This sensor feeds back the outlet nitrogen oxide concentration signal to the intelligent control unit to form a closed-loop control and adjust the injection volume of the urea injection device.

[0016] Specifically, the intelligent control unit is also connected to a fault diagnosis module, which can monitor the working status of the data acquisition module, the multi-level purification module and the regeneration execution module. When a component signal is abnormal, a fault code is output to the vehicle dashboard.

[0017] Specifically, a mixing baffle is provided between the low-temperature catalytic component and the particulate collection component. The mixing baffle is a spiral metal plate used to enhance the uniformity of contact between the exhaust gas and the catalyst.

[0018] Specifically, the intelligent control unit also communicates with the vehicle remote monitoring platform via the CAN bus, and can upload exhaust gas purification parameters, regeneration times and fault information to the platform to realize remote monitoring and maintenance.

[0019] The beneficial effects of this invention are: (1) The vehicle exhaust gas purification and emission control system described in this invention achieves efficient purification of various pollutants under all operating conditions through the synergistic effect and structural optimization of multi-level purification modules. Among them, the low-temperature catalytic component, combined with the preheating unit, effectively solves the problem of insufficient catalyst activity during the engine cold start stage, and significantly improves the purification effect of carbon monoxide and hydrocarbons in the early stage of cold start; the particulate capture component can accurately capture particulate matter in the exhaust gas, avoiding its direct emission; the selective catalytic reduction component specifically treats nitrogen oxides, and together with the spiral mixing baffle, enhances the uniformity of contact between the exhaust gas and the catalyst, ensuring that various pollutants can be effectively treated under different driving conditions, avoiding the phenomenon of single pollutant purification not meeting the standards.

[0020] (2) The vehicle exhaust purification and emission control system described in this invention relies on the dynamic control strategy and closed-loop feedback mechanism of the intelligent control unit to achieve precision and energy saving in the purification process. The intelligent control unit adjusts the power of the preheating unit and the amount of urea injection in stages according to the engine operating conditions (such as speed and load) and real-time data from various sensors, avoiding the secondary pollution caused by excessive urea injection or the problem of excessive nitrogen oxides caused by insufficient injection in traditional open-loop control; at the same time, by dynamically monitoring the temperature and pressure of the particulate matter collection component regeneration process, it ensures that the regeneration process is both thorough and does not consume excessive energy, reducing unnecessary fuel and electricity waste.

[0021] (3) The vehicle exhaust gas purification and emission control system described in this invention significantly improves the reliability and service life of the particulate collection components by optimizing the working mode of the regeneration execution module. The regeneration execution module adopts a combination of electric heating and fuel injection assistance, and controls the injection precisely by adjusting the power through pulse width modulation and synchronizing the engine exhaust stroke. This avoids the problems of excessive temperature causing filter cracking or insufficient temperature causing incomplete regeneration. At the same time, the start and stop of the regeneration process are based on the pressure difference threshold, which avoids the wear and tear on the components caused by frequent regeneration, extends the replacement cycle of core components, and reduces the user's maintenance costs.

[0022] (4) The vehicle exhaust gas purification and emission control system described in this invention enhances the convenience of system operation and maintenance and operational stability by combining a fault diagnosis module with a remote monitoring function. The fault diagnosis module can monitor the working status of each component in real time, and immediately output a fault code reminder once a component malfunctions, so as to avoid the system paralysis or emission exceeding the standard due to component failure; the remote monitoring function can upload purification parameters, regeneration status and fault information to the platform, so that users or maintenance personnel can remotely grasp the system status and arrange maintenance in a timely manner, which is especially suitable for scenarios such as commercial vehicles that need to operate at high intensity for a long time, reducing the losses caused by downtime maintenance.

[0023] (5) The vehicle exhaust purification and emission control system described in this invention has broad vehicle compatibility and can flexibly adapt to the exhaust characteristics of different types of engines. By appropriately adjusting the system structure and control strategy, it can meet the pollutant emission control requirements of gasoline vehicles during the cold start phase, and also adapt to the characteristics of diesel vehicles with large particulate matter emissions and large exhaust temperature fluctuations. It eliminates the need to develop a dedicated system for a single vehicle model, reduces the difficulty of technology promotion, and helps to achieve a unified improvement in exhaust purification effect across multiple vehicle types, better meeting the stringent emission standards of different regions. Attached Figure Description

[0024] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0025] Figure 1This is a diagram illustrating the architecture of the vehicle exhaust purification and emission control system provided by the present invention. Detailed Implementation

[0026] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0027] like Figure 1 As shown, the vehicle exhaust purification and emission control system of the present invention includes a multi-stage purification module, a data acquisition module, an intelligent control unit, and a regeneration execution module. The modules are connected by electrical and mechanical connections to form an organic whole.

[0028] Multi-stage purification module: A low-temperature catalytic converter, a particulate filter, and a selective catalytic reduction (SCR) module are connected in series along the exhaust gas flow direction. The low-temperature catalytic converter uses cordierite honeycomb ceramic as a carrier, coated with a palladium-rhodium composite catalyst. A nickel-chromium alloy heating wire is wound around the outside of the carrier as a preheating unit, with heating power adjustable from 500W to 1500W. This is used to quickly increase the catalyst temperature during engine cold starts, enhancing the purification effect of carbon monoxide and hydrocarbons. The particulate filter uses a silicon carbide porous ceramic filter with a porosity of 55%-65%. A pressure detection channel is installed inside the filter to monitor the pressure difference across the filter in real time and determine the degree of blockage. The SCR module uses a vanadium-tungsten-titanium composite oxide catalyst and is equipped with an electromagnetic urea injection device. The urea injection quantity can be dynamically adjusted according to engine operating conditions.

[0029] Data Acquisition Module: Composed of multiple sensors, covering the entire exhaust gas purification process and engine operating parameters. A first temperature sensor, a first pressure sensor, and a hydrocarbon concentration sensor are installed at the inlet of the multi-stage purification module to collect the temperature, pressure, and initial hydrocarbon concentration of the raw exhaust gas. A second temperature sensor and a particulate matter concentration sensor are installed between the cryogenic catalytic converter and the particulate matter trap to monitor the exhaust gas temperature and particulate matter concentration after cryogenic catalysis. A third temperature sensor and a second pressure sensor are installed between the particulate matter trap and the selective catalytic reduction (SCR) module to collect the exhaust gas temperature after particulate matter trapping and the outlet pressure of the particulate matter trap. A nitrogen oxide (NOx) concentration sensor is installed at the outlet of the SCR module to monitor the NOx concentration in the final exhaust gas. Simultaneously, by communicating with the engine ECU, operating parameters such as engine speed and load are obtained, providing data support for intelligent control.

[0030] Intelligent Control Unit: As the core of the system, it adopts an STM32F4 series microcontroller and stores a multi-stage purification control strategy based on engine operating conditions. It receives various parameter signals transmitted from the data acquisition module, performs AD conversion and data analysis, and outputs corresponding control signals. During the cold start phase, when the first temperature sensor detects a value below 200℃, it outputs a signal to control the preheating unit of the low-temperature catalytic converter to operate at maximum power until the second temperature sensor detects a value of 250℃ (the optimal activity temperature of the catalyst). Subsequently, it dynamically adjusts the heating power based on the exhaust gas temperature. During normal driving, it combines engine speed, load signals, and particulate matter concentration sensor data to output a signal to the urea injection device to adjust the urea injection quantity. Simultaneously, it forms a closed-loop control through feedback signals from the nitrogen oxide concentration sensor to ensure nitrogen oxide purification efficiency. When the pressure difference between the inlet and outlet of the particulate matter collection component exceeds 15kPa, it is determined that the filter is clogged, and an output signal is sent to activate the regeneration execution module.

[0031] The regeneration execution module includes an electric heating device and a fuel injection auxiliary device, both located at the inlet of the particulate filter assembly. The electric heating device uses PWM (Pulse Width Modulation) to regulate power, while the fuel injection auxiliary device operates synchronously with the engine's exhaust stroke. During regeneration, the intelligent control unit, based on the signal from the second temperature sensor, first controls the electric heating device to raise the exhaust gas temperature to 300℃-350℃, then activates the fuel injection auxiliary device, injecting 5-10mg of fuel in a single injection. This fuel combustion further raises the internal temperature of the particulate filter assembly to 550℃-600℃ and maintains this temperature for 10-15 minutes, ensuring complete combustion of particulate matter. Simultaneously, the pressure difference is monitored in real time by a second pressure sensor. When the pressure difference drops below 5kPa, the regeneration process stops to prevent overheating and damage to the filter element.

[0032] In addition, the system is equipped with a fault diagnosis module and a remote communication module. The fault diagnosis module connects to the intelligent control unit to monitor the working status of each sensor and actuator. When an abnormal signal is detected (such as no output from a sensor or no response from an actuator), a fault code is generated and sent to the vehicle's dashboard to remind the user to perform timely maintenance. The remote communication module connects to the vehicle's remote monitoring platform via a CAN bus to upload data such as exhaust gas purification efficiency, DPF regeneration times, and fault information to the platform, facilitating fleet management and remote fault diagnosis.

[0033] Example 1: Application of Gasoline Vehicle On-board Exhaust Purification and Emission Control System This embodiment focuses on a 1.6L gasoline engine vehicle, detailing the specific structure, installation method, and working process of the on-board exhaust purification and emission control system.

[0034] System structure and installation: The multi-stage purification module features a 3mm thick stainless steel shell, providing excellent high-temperature and corrosion resistance. The low-temperature catalytic component uses cordierite honeycomb ceramic with a diameter of 110mm and a length of 150mm as its carrier. The carrier has a pore density of 400 cpsi (pores per square inch). The palladium-rhodium composite catalyst coated on the surface contains 2g / L palladium and 0.5g / L rhodium, with a catalyst coating amount of 150g / L. The preheating unit uses a 5m long, 0.5mm diameter nickel-chromium alloy heating wire wound around the outside of the carrier. A mica insulation layer is placed between the heating wire and the carrier to prevent short circuits. The heating wire is connected to the power output terminal of the intelligent control unit via high-temperature resistant silicone wire with a temperature rating of 250℃.

[0035] The filter element of the particulate trap is a porous silicon carbide ceramic with a diameter of 110 mm and a length of 200 mm. The average pore size of the filter element is 15 μm, and the porosity is 60%. Four axially oriented pressure detection channels, each 2 mm in diameter, are located at 0°, 90°, 180°, and 270° of the filter element. The probe of a second pressure sensor is inserted into these channels to collect real-time pressure data within the filter element. A 10 mm thick ceramic fiber insulation layer is filled between the outer shell of the particulate trap and the filter element to reduce heat loss.

[0036] The catalyst support for the selective catalytic reduction (SCR) component is a cordierite honeycomb ceramic with a diameter of 110 mm and a length of 200 mm, coated with a vanadium-tungsten-titanium composite oxide catalyst. The vanadium content is 1.5% (mass fraction), the tungsten content is 5% (mass fraction), and the catalyst coating amount is 120 g / L. The urea injection system has a 10 L urea tank located on the side of the vehicle chassis. The tank contains a level sensor and a temperature sensor to monitor the urea level and temperature, preventing urea crystallization. The electromagnetic injection valve has an injection pressure of 0.8 MPa and an injection angle of 60°. It is installed in the exhaust gas passage between the particulate filter and the SCR component, with the injection port facing the exhaust gas flow direction to ensure thorough mixing of the urea solution and the exhaust gas.

[0037] All sensors in the data acquisition module are automotive-grade products with a temperature range of -40℃ to 300℃. The first temperature sensor, the first pressure sensor, and the hydrocarbon concentration sensor are integrated into a single sensor assembly, installed at the engine exhaust manifold outlet, 15cm from the engine block, for rapid acquisition of raw exhaust gas parameters. The second temperature sensor and particulate matter concentration sensor are installed at the outlet flange of the cryogenic catalytic converter, with the flange bolted together and a graphite gasket to ensure no exhaust gas leakage. The third temperature sensor and the second pressure sensor are installed at the outlet flange of the particulate trap assembly. The nitrogen oxide concentration sensor is installed at the outlet of the selective catalytic reduction assembly, 20cm from the catalyst outlet, ensuring that the detected exhaust gas is the fully reacted product. The speed sensor and load sensor are connected to the engine ECU via a CAN bus to acquire engine operating data in real time.

[0038] The intelligent control unit uses an STM32F407VGT6 microcontroller, which features a 168MHz clock speed, 1MB of flash memory, and 192KB of RAM, meeting the real-time processing requirements of multiple parameters. The control unit's housing is made of aluminum alloy with heat sinks to ensure stable operation in high-temperature environments. The control unit is installed inside the dashboard below the driver's compartment and is connected to various sensors and actuators via wires. The wire harness is protected by corrugated tubing and fixed to a wiring harness bracket on the vehicle chassis.

[0039] The electric heating device of the regeneration execution module has a ring structure with an inner diameter of 110mm, which matches the exhaust gas passage at the inlet end of the particulate filter assembly. The heating element of the electric heating device is a nickel-chromium alloy strip, 5mm wide and 0.1mm thick, with a total power of 2000W, controlled by PWM modulation at a modulation frequency of 1kHz. The fuel injector of the fuel injection auxiliary device is installed on the exhaust gas passage 10cm upstream of the electric heating device. The fuel injector is connected to the vehicle's fuel line, and a solenoid valve is installed in the middle, controlled by the intelligent control unit.

[0040] Work process: Cold Start Phase: When the driver starts the engine, the intelligent control unit is simultaneously powered on, and the data acquisition module begins operation. The first temperature sensor detects an exhaust gas temperature of 30°C (below 200°C), and the intelligent control unit immediately outputs the first control signal, causing the preheating unit of the low-temperature catalytic converter to operate at its maximum power of 1500W. Simultaneously, the engine speed is measured at 800 rpm and the load at 20% by the speed and load sensors, indicating a cold start condition. As the preheating unit operates, the exhaust gas temperature detected by the second temperature sensor gradually increases. When the temperature reaches 250°C, the intelligent control unit reduces the preheating unit power to 800W and dynamically adjusts the power based on the real-time signal from the second temperature sensor to maintain the catalyst temperature between 250°C and 300°C. At this time, the hydrocarbon concentration sensor detects that the outlet hydrocarbon concentration has decreased from the initial 1000 ppm to below 250 ppm, achieving a purification efficiency of over 75%.

[0041] During normal driving: After 5 minutes of driving, the engine reaches normal operating temperature, and the exhaust gas temperature rises to 400℃-500℃. The intelligent control unit shuts down the preheating unit of the low-temperature catalytic converter, relying solely on the exhaust gas temperature to maintain catalyst activity. At this time, the engine speed reaches 2000 rpm, the load reaches 50%, and the particulate matter concentration sensor detects a particulate matter concentration of 10 mg / m³ in the exhaust gas. Based on a preset control strategy, the intelligent control unit outputs a second control signal to the urea injection device, controlling the injection valve to inject urea solution at a rate of 10 mg / s. The nitrogen oxide concentration sensor monitors the outlet nitrogen oxide concentration in real time. When the detected value is 80 ppm (the inlet concentration is approximately 500 ppm), the intelligent control unit appropriately increases the urea injection rate to 12 mg / s, reducing the outlet nitrogen oxide concentration to below 50 ppm, achieving a purification efficiency of 90%.

[0042] Particulate filter regeneration stage: After the vehicle has traveled 1000km, the data acquisition module detects that the inlet pressure of the particulate filter is 120kPa and the outlet pressure is 100kPa, with a pressure difference of 20kPa (greater than the preset threshold of 15kPa). The intelligent control unit determines that the regeneration process needs to be initiated. At this time, the vehicle is traveling at high speed, the engine speed is 2500r / min, the load is 60%, and the second temperature sensor detects that the exhaust gas temperature is 350℃. The intelligent control unit first outputs a third control signal to make the electric heating device of the regeneration execution module operate at 1500W power. After 5 minutes, the second temperature sensor detects that the exhaust gas temperature has risen to 450℃. The intelligent control unit activates the fuel injection assist device to inject fuel synchronously with the engine exhaust stroke, with a single injection volume of 8mg and an injection frequency consistent with the engine speed (approximately 41.7Hz). As the fuel burns, the internal temperature of the particulate filter gradually rises to 580℃ and is maintained for 12 minutes. During this process, the second pressure sensor monitors the pressure difference in real time. When the pressure difference drops to 4 kPa, the intelligent control unit first shuts off the fuel injection assist device. After the temperature drops below 400℃, the electric heating device is shut off, and the regeneration process ends. At this time, the particulate matter concentration sensor detects that the particulate matter concentration in the exhaust gas has dropped to below 2 mg / m³, and the particulate matter collection component returns to normal operation.

[0043] Fault Diagnosis and Early Warning: If the urea tank level sensor detects that the urea level is below 1L, the intelligent control unit generates a "low urea" fault code and sends it to the vehicle's instrument panel, illuminating the warning light. If the nitrogen oxide concentration sensor has no signal output, the intelligent control unit generates a "sensor fault" fault code and adjusts the urea injection volume to a safe value to prevent emissions from exceeding standards. This fault information is also uploaded to the vehicle monitoring platform via a remote communication module, allowing platform staff to promptly remind users to perform maintenance.

[0044] This embodiment achieves highly efficient purification of gasoline vehicle exhaust through the above structure and working process. According to third-party testing, the system achieves a hydrocarbon purification efficiency of 78% during the cold start phase, a nitrogen oxide purification efficiency of 92% during normal driving, and a particulate matter purification efficiency of 96%. The DPF regeneration energy consumption is reduced by 60% compared with the existing technology, and it fully meets the requirements of the China VI b emission standard.

[0045] Example 2: Application of diesel vehicle on-board exhaust purification and emission control system This embodiment is designed for commercial vehicles with a 3.0L diesel engine. Based on Embodiment 1, the system is adapted and adjusted to suit the characteristics of high exhaust gas temperature and large particulate matter emissions of diesel engines. The system adjustment content, installation method and working effect are described in detail.

[0046] System adjustment and installation: In the multi-stage purification module, the carrier size of the low-temperature catalytic component has been adjusted to cordierite honeycomb ceramic with a diameter of 140mm and a length of 200mm, and a pore density of 300cpsi. In the palladium-rhodium composite catalyst coated on the surface, the palladium content has been increased to 3g / L, while the rhodium content remains at 0.5g / L, to enhance the oxidation capacity for high-concentration hydrocarbons in diesel vehicle exhaust. The total power of the nickel-chromium alloy heating wire in the preheating unit has been increased to 2000W, and the diameter of the heating wire has been increased to 0.6mm to ensure rapid temperature increase of the catalyst.

[0047] The filter element of the particulate trap uses porous silicon carbide ceramic with a diameter of 140mm and a length of 250mm. The average pore size has been reduced to 12μm, and the porosity has been adjusted to 55% to improve the capture efficiency of fine particulate matter (PM2.5) in diesel vehicle exhaust. The number of pressure detection channels inside the filter element has been increased to six, with a more even distribution to ensure the accuracy of pressure difference detection. Simultaneously, a water-cooling jacket has been added to the outside of the particulate trap housing. This jacket is connected to the vehicle's cooling system. When the temperature exceeds 650℃ during regeneration, the water-cooling system is activated to prevent overheating of the housing and damage to surrounding components.

[0048] The catalyst support of the selective catalytic reduction (SCR) component has a diameter of 140 mm and a length of 250 mm. The vanadium content in the coated vanadium-tungsten-titanium composite oxide catalyst is increased to 2% (mass fraction) to enhance its reduction activity for nitrogen oxides at high temperatures. The urea tank volume of the urea injection system is increased to 20 L, the injection pressure of the injection valve is increased to 1.0 MPa, and the injection quantity adjustment range is expanded to 5-20 mg / s to adapt to the large fluctuations in nitrogen oxide concentration in diesel vehicle exhaust.

[0049] The data acquisition module now includes an exhaust flow sensor, installed at the inlet of the multi-stage purification module, to collect exhaust gas flow data, providing more comprehensive parameters for precise control of urea injection. Simultaneously, the particulate matter concentration sensor has been replaced with a laser scattering sensor, expanding the detection range to 0-100 mg / m³, meeting the high particulate matter concentration detection requirements of diesel vehicles.

[0050] The control strategy of the intelligent control unit has been adjusted. The preheating threshold temperature during the cold start phase has been reduced to 180℃ because the exhaust gas temperature is lower when the diesel engine is cold-started. The pressure difference threshold during the regeneration phase has been adjusted to 20kPa because diesel vehicles emit more particulate matter and the DPF clogs faster. The calculation model for urea injection quantity has been updated with an exhaust flow parameter to better match the injection quantity with the exhaust gas flow and nitrogen oxide concentration. The formula is: Injection quantity = K × speed × load × exhaust flow × inlet nitrogen oxide concentration, where K is a correction coefficient with a value range of 0.001-0.003.

[0051] The power of the electric heating device in the regeneration execution module has been increased to 2500W, and the single injection volume of the fuel injection auxiliary device has been increased to 10-15mg. At the same time, a heat insulation plate is installed between the electric heating device and the particulate collection component to reduce heat conduction to the electric heating device and extend its service life.

[0052] Work process and results: Cold start phase: After the diesel engine starts, the first temperature sensor detects an exhaust gas temperature of 25°C. The intelligent control unit activates the preheating unit of the low-temperature catalytic converter, operating at 2000W. Due to the low engine speed (approximately 600 r / min), low load (approximately 15%), and low exhaust gas flow during a cold start, the preheating unit can quickly raise the catalyst temperature. After 10 minutes, the second temperature sensor detects a temperature of 250°C, and the intelligent control unit reduces the preheating power to 1000W. At this time, the hydrocarbon concentration sensor detects that the outlet concentration has decreased from the initial 1500 ppm to below 300 ppm, achieving a purification efficiency of 80%.

[0053] During normal driving: When the vehicle is fully loaded, the engine speed is 1800 r / min, the load is 80%, the exhaust flow sensor detects an exhaust gas flow rate of 80 m³ / h, and the inlet nitrogen oxide concentration sensor detects a concentration of 800 ppm. The intelligent control unit calculates the injection rate as 18 mg / s based on the injection formula and controls the urea injection device to inject at this rate. The nitrogen oxide concentration sensor detects an outlet concentration of 70 ppm, achieving a purification efficiency of 91.25%. When the vehicle decelerates, the engine speed drops to 1000 r / min, the load drops to 30%, the exhaust gas flow rate drops to 40 m³ / h, and the inlet nitrogen oxide concentration drops to 300 ppm. The intelligent control unit adjusts the injection rate to 6 mg / s, maintaining the outlet nitrogen oxide concentration below 30 ppm.

[0054] Particulate Filter Assembly Regeneration Stage: After the vehicle has traveled 500km, the pressure difference between the inlet and outlet of the particulate filter assembly reaches 25kPa, and the intelligent control unit initiates the regeneration process. At this time, the engine is idling at 700r / min, with a load of 10% and an exhaust gas temperature of 200℃. The intelligent control unit first controls the electric heating device to operate at 2500W. After 15 minutes, the exhaust gas temperature rises to 400℃, and the fuel injection assist device is activated, with a single injection quantity of 12mg and an injection frequency of 11.7Hz. As combustion proceeds, the internal temperature of the particulate filter assembly rises to 590℃ and is maintained for 15 minutes. During this period, the water-cooling jacket monitors the outer shell temperature in real time. When the temperature exceeds 600℃, the cooling system is activated to control the temperature between 550℃ and 600℃. After regeneration, the pressure difference drops to 5kPa, and the particulate matter concentration sensor detects an outlet particulate matter concentration of 1mg / m³, achieving a regeneration efficiency of 98%.

[0055] Long-term operational performance: After accumulating 5000km of operation on diesel vehicles, the system demonstrated an average nitrogen oxide purification efficiency of 88% and an average particulate matter purification efficiency of 97%. The DPF regeneration cycle was 10 times, with an average fuel consumption of 0.25L per regeneration cycle, representing a reduction of over 50% compared to existing technologies. Furthermore, the fault diagnosis module detected no component abnormalities, indicating stable system operation and meeting the demands of high-intensity, long-term operation in commercial vehicles.

[0056] This embodiment adapts and adjusts the system structure and control strategy to enable the vehicle exhaust purification and emission control system to effectively address the characteristics of diesel vehicle exhaust, significantly improving purification efficiency and reducing operating costs.

[0057] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of protection claimed by the present invention. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A vehicle-mounted exhaust gas purification and emission control system, characterized in that, include: The multi-stage purification module is composed of a low-temperature catalytic component, a particulate trap component, and a selective catalytic reduction component connected in series along the exhaust gas flow direction. The low-temperature catalytic component is used for the preliminary purification of carbon monoxide and hydrocarbons in the exhaust gas during the engine cold start stage. The particulate trap component is used to capture particulate matter in the exhaust gas. The selective catalytic reduction component is used to reduce nitrogen oxides in the exhaust gas. The data acquisition module includes a first temperature sensor, a first pressure sensor, and a hydrocarbon concentration sensor located at the inlet of the multi-stage purification module; a second temperature sensor and a particulate matter concentration sensor located between the low-temperature catalytic component and the particulate matter collection component; a third temperature sensor and a second pressure sensor located between the particulate matter collection component and the selective catalytic reduction component; and a speed sensor and a load sensor that are communicatively connected to the engine ECU. The intelligent control unit is electrically connected to the data acquisition module and the multi-stage purification module respectively. The intelligent control unit stores a purification control strategy based on engine operating conditions. It can receive parameter signals transmitted by the data acquisition module, analyze and process them, and output a first control signal to the preheating unit of the low-temperature catalytic component and a second control signal to the urea injection device of the selective catalytic reduction component. The regeneration execution module is electrically connected to the intelligent control unit. The regeneration execution module includes an electric heating device and a fuel injection auxiliary device disposed at the inlet end of the particulate collection component. It can receive the third control signal output by the intelligent control unit to realize the active regeneration of the particulate collection component. The intelligent control unit determines whether to start the regeneration execution module by comparing the pressure difference between the inlet and outlet of the particulate collection component with a preset threshold, and adjusts the power of the electric heating device and the fuel injection quantity according to the signal of the second temperature sensor during the regeneration process.

2. The vehicle exhaust purification and emission control system according to claim 1, characterized in that: The carrier of the low-temperature catalytic component is cordierite honeycomb ceramic, and the surface of the carrier is coated with a palladium-rhodium composite catalyst. The preheating unit is a nickel-chromium alloy heating wire wound around the outside of the carrier, and the power adjustment range of the heating wire is 500W-1500W.

3. The vehicle exhaust purification and emission control system according to claim 1, characterized in that: The filter body of the particle collection component is made of silicon carbide porous ceramic with a porosity of 55%-65%. The filter body has a pressure detection channel distributed along the axial direction inside, and the second pressure sensor collects the internal pressure of the filter body through this channel.

4. The vehicle exhaust purification and emission control system according to claim 1, characterized in that: The catalyst of the selective catalytic reduction component is a vanadium-tungsten-titanium composite oxide. The urea injection device includes a urea tank, an electromagnetic injection valve, and an injection controller. The injection controller atomizes the urea solution and injects it into the exhaust gas passage according to the second control signal of the intelligent control unit. The urea injection quantity is positively correlated with the engine speed and load.

5. The vehicle exhaust purification and emission control system according to claim 1, characterized in that: The control strategies of the intelligent control unit include cold start phase strategy, normal driving phase strategy and regeneration phase strategy. During the cold start phase, when the value detected by the first temperature sensor is below 200°C, the first control signal is output to make the preheating unit operate at maximum power until the value detected by the second temperature sensor reaches 250°C. During normal driving, the urea injection volume is dynamically adjusted according to the speed and load signals. During the regeneration phase, when the pressure difference exceeds 15 kPa, the regeneration execution module is activated, raising the internal temperature of the particle collection component to 550℃-600℃ and maintaining it for 10-15 minutes.

6. The vehicle exhaust purification and emission control system according to claim 1, characterized in that: The electric heating device of the regeneration execution module uses PWM pulse width modulation to adjust the power, and the injection time of the fuel injection auxiliary device is synchronized with the engine exhaust stroke, with a single injection amount of 5-10mg.

7. The vehicle exhaust purification and emission control system according to claim 1, characterized in that: The data acquisition module also includes a nitrogen oxide concentration sensor located at the outlet of the selective catalytic reduction component. This sensor feeds back the outlet nitrogen oxide concentration signal to the intelligent control unit to form a closed-loop control and adjust the injection volume of the urea injection device.

8. The vehicle exhaust purification and emission control system according to claim 1, characterized in that: The intelligent control unit is also connected to a fault diagnosis module, which can monitor the working status of the data acquisition module, the multi-level purification module and the regeneration execution module. When a component signal is abnormal, a fault code is output to the vehicle dashboard.

9. The vehicle exhaust purification and emission control system according to claim 1, characterized in that: A mixing baffle is provided between the low-temperature catalytic component and the particulate collection component. The mixing baffle is a spiral metal plate used to enhance the uniformity of contact between the exhaust gas and the catalyst.

10. The vehicle exhaust purification and emission control system according to claim 1, characterized in that: The intelligent control unit also communicates with the vehicle remote monitoring platform via the CAN bus, and can upload exhaust gas purification parameters, regeneration times and fault information to the platform to realize remote monitoring and maintenance.

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