Urea decomposition device with swirl generator

Abstract

The application discloses a urea decomposition device with a cyclone generator, which comprises a cyclone particle collector and a controller. The cyclone particle collector comprises a cyclone generator, a cyclone barrel, a urea nozzle interface located downstream of the cyclone generator, a particle collection barrel located at the lower opening of the cyclone barrel, a heating sensor unit located at the bottom of the particle collection barrel, and an air flow outlet pipe in communication with the cyclone barrel. The heating sensor unit is electrically connected with the controller. Tail gas enters the cyclone generator and generates a rotating air flow. Urea droplets sprayed from a urea nozzle enter the rotating air flow through the urea nozzle interface, rotate and decompose. Undecomposed large-particle urea droplets are separated from the main air flow and then flow into the particle collection barrel. A mixture of small-particle urea droplets, ammonia gas generated by decomposition and tail gas flows out through the air flow outlet pipe. The application reduces energy consumption, improves urea decomposition effectiveness, reduces the influence of sulfur on downstream catalysts, and filters and removes part of soot particles.

Description

Technical Field

[0001] This invention relates to a urea decomposition device, and more particularly to a urea decomposition device with a swirl generator. Background Technology

[0002] To remove nitrogen oxides (NOx) from engine exhaust, selective catalytic reduction (SCR) technology is generally used, utilizing the reaction between a reducing agent and NOx to remove them. Typically, an SCR system comprises five parts: a catalyst assembly, a sensor module, a controller unit, a reducing agent storage device, and a reducing agent metering injection device. The catalyst assembly includes catalyst encapsulation, exhaust piping, and a urea decomposition device; the sensor module generally includes an exhaust temperature sensor and a NOx sensor; the controller unit can be a standalone catalytic reduction system controller (DCU) or integrated with the engine control unit (ECU); the reducing agent storage device stores and prepares the reducing agent, typically including a reducing agent heating device, a reducing agent level sensor, a reducing agent temperature sensor, and a reducing agent quality sensor; the reducing agent metering injection device precisely injects the reducing agent or reducing agent carrier into the exhaust gas at a specific dosage, mixing it with the exhaust gas. The uniformly mixed exhaust gas reacts on the catalyst surface, thereby removing NOx. Currently, the most widely used SCR system in practical applications is the one using ammonia as a reducing agent. To ensure safe storage and use, as well as accurate metering, urea solution is used as a carrier for the ammonia reducing agent. In such a system, the reducing agent metering injection device injects urea solution into the exhaust gas. Under the action of the high-temperature exhaust gas, urea undergoes pyrolysis and hydrolysis to produce ammonia, which then reacts with nitrogen oxides. This type of reducing agent metering injection device is also called an automotive urea metering injection device, or simply a urea metering injection device.

[0003] There are two main injection methods for urea metering and injection devices. One is the airless method, in which the urea metering and injection system includes a urea pump and a urea nozzle. The urea pump pressurizes the urea solution and injects it into the exhaust gas flow of the SCR system through the urea nozzle. The flow rate of the urea solution is controlled by the on / off state of the urea nozzle. The commonly used control method is pulse width modulation (PWM), which controls the urea solution injection flow rate by adjusting the nozzle opening time within a repetitive fixed cycle. The other method is the air-assisted method. In this method, the urea solution is first metered by the urea pump or other urea metering device, and then mixed with compressed air. The resulting gas-liquid mixture enters the exhaust gas flow.

[0004] Compared to air-assisted injection, airless injection does not introduce compressed air, thus preserving exhaust gas energy and enabling more efficient hydrolysis and pyrolysis of urea. Furthermore, the metering method of airless injection can reduce the impact of pressure fluctuations and other factors through compensation (adjusting the PWM pulse width), resulting in high injection accuracy and better adaptability to increasingly stringent OBD requirements. These advantages of airless injection have led to its increasingly widespread application.

[0005] However, due to limitations in injection pressure, the atomized particle size of airless injection is larger compared to air-assisted injection. Larger urea droplets are less likely to mix evenly with the exhaust gas flow and also hinder the hydrolysis and pyrolysis of urea. Uneven mixing of urea droplets reduces SCR reaction efficiency, while incompletely hydrolyzed and pyrolyzed urea droplets can crystallize in the SCR system, potentially clogging the exhaust pipe. To address these issues, airless injection systems typically employ a urea decomposition device with a mixer in conjunction with the urea nozzle to further pulverize urea particles and achieve more uniform mixing.

[0006] However, the complex structure of the urea decomposition device itself obstructs the exhaust gas flow, increasing engine back pressure and thus fuel consumption. Generally, the less crystallization occurs in the urea decomposition device, the more complex its structure and the greater its impact on engine back pressure. Furthermore, to enhance hydrolysis and pyrolysis in the low-temperature exhaust gas to reduce crystallization and improve SCR reaction efficiency under low-temperature conditions, the exhaust gas must be heated. Since the exhaust gas flow rate is much greater than the urea solution flow rate, heating the exhaust gas to improve urea decomposition is highly uneconomical.

[0007] In addition, sulfides are a common impurity in engine fuel. The combustion of sulfides produces gaseous sulfur oxides (mainly sulfur dioxide) and sulfur-containing particulate matter. These sulfur-containing substances can poison certain SCR catalysts, such as copper-based molecular sieve SCR catalysts, and in severe cases, cause catalyst deactivation. Heating the catalyst can largely restore its activity (this process is also called desulfurization regeneration), but frequent desulfurization regeneration leads to increased engine fuel consumption and reduces the lifespan of the catalyst and aftertreatment system.

[0008] Therefore, it is urgent to solve the above problems. Summary of the Invention

[0009] Purpose of the invention: The purpose of this invention is to provide a urea decomposition device that improves the efficiency of urea decomposition, reduces the impact of sulfur on downstream catalysts, and partially filters out carbon soot particles while reducing energy consumption.

[0010] Technical Solution: To achieve the above objectives, this invention discloses a urea decomposition device with a cyclone generator, comprising a cyclone particle collector and a controller. The cyclone particle collector includes a cyclone generator, a cyclone cylinder connected to the outlet of the cyclone generator, a urea nozzle interface located on the cyclone cylinder and downstream of the cyclone generator, a particle collection bucket located at the lower opening of the cyclone cylinder, a heating sensor unit located at the bottom of the particle collection bucket, and an air outlet pipe connected to the cyclone cylinder. The heating sensor unit is electrically connected to the controller. The exhaust gas enters the cyclone generator and generates a rotating airflow. Urea droplets ejected from the urea nozzle enter the rotating airflow through the urea nozzle interface and rotate, accompanied by decomposition. Undecomposed large urea droplets separate from the main airflow and then flow into the particle collection bucket, while the mixture of small urea droplets, ammonia generated from decomposition, and exhaust gas flows out through the air outlet pipe.

[0011] The cyclone cylinder includes an outer cylinder and an inner cylinder that are concentrically arranged, as well as swirl blades located between the outer cylinder and the inner cylinder. Engine exhaust gas first enters the outer cylinder and generates swirl through the swirl blades. A mixture of small urea droplets, ammonia gas produced by decomposition, and exhaust gas enters the air outlet pipe through the inner cylinder and flows out of the urea decomposition device.

[0012] Preferably, the inner wall of the cyclone cylinder is coated with a catalyst coating structure, which includes a catalyst coating for urea hydrolysis.

[0013] Furthermore, the heating sensing unit includes a particle quantity sensor for detecting particulate matter and a heating device for heating urea droplets, the particle quantity sensor and the heating device being electrically connected to the controller.

[0014] Furthermore, the upper surface of the heating device is coated with a catalyst coating that contacts the urea flowing into the particle collection tank.

[0015] Preferably, the heating device is provided with a heating unit, which includes a heat conductor and an electric heating element. The electric heating element is electrically connected to and controlled by the controller.

[0016] Furthermore, the particle quantity sensor includes two detection electrodes, and the controller includes a reactance measurement circuit for measuring the impedance change between the two particle quantity detection electrodes.

[0017] Furthermore, the controller controls the heating unit based on the reactance change measured by the reactance measurement circuit; the impedance value Zs detected by the two particle quantity detection electrodes is transmitted to the controller, and the exhaust gas temperature value T161 of the cyclone particle collector is transmitted to the controller. The controller compares the impedance value Zs with the threshold Thd_PLL. When the impedance value Zs is greater than the threshold Thd_PLL, it compares the exhaust gas temperature value T161 with the threshold Thd_STL. When T161 is less than Thd_STL, it outputs a start control signal for the heating unit. When T161 is not less than Thd_STL, it compares the temperature value T161 with another threshold Thd_STH. When T161 is greater than Thd_STH, it outputs a stop control signal for the heating unit. When the impedance value Zs is not greater than the threshold Thd_PLL, it outputs a stop control signal for the heating unit.

[0018] Preferably, the device further includes a brake kinetic energy recovery device electrically connected to the controller. The brake kinetic energy recovery device includes a transmission device connected to the wheel and a kinetic energy to electrical energy conversion device connected to the transmission device. The controller uses the electrical energy generated by the brake kinetic energy recovery device to control the heating unit.

[0019] Furthermore, the particle collection tank contains a collecting substance for sulfate and sulfite ions, which reacts with compounds containing sulfate and sulfite ions to form salts.

[0020] Beneficial Effects: Compared with the prior art, the present invention has the following significant advantages: The present invention uses a vortex generator independent of the cyclone cylinder to generate vortexes, thereby achieving the designed vortex velocity without affecting the structure of the cyclone cylinder. Simultaneously, the urea nozzle interface is located downstream of the vortex generator, allowing the urea solution to be sprayed into a rotating airflow. Large urea droplets separate from the main airflow in the vortex airflow, are collected, and then centrally heated for decomposition. Since only a portion of the urea is heated without decomposing large particles, rather than heating all urea particles or the exhaust gas, the heating power can be greatly reduced, lowering energy consumption and significantly improving heating and urea decomposition efficiency. Furthermore, the urea decomposition device in the present invention can collect and solidify sulfur, reducing the amount of sulfur-containing compounds entering the catalyst and thus avoiding frequent desulfurization regeneration of the catalyst. The urea decomposition device in the present invention also filters out soot particles, assisting the downstream particulate filter in removing some soot. Simultaneously, during the regeneration of the downstream particulate filter, the high-temperature exhaust gas also helps remove urea crystals and soot from the particulate collection tank. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of the present invention;

[0022] Figure 2 This is a schematic diagram of the cyclone generator in this invention;

[0023] Figure 3 This is a cross-sectional view of the cyclone generator in this invention;

[0024] Figure 4 This is a schematic diagram of the cyclone cylinder in this invention;

[0025] Figure 5 This is a schematic diagram of the heating sensing unit in this invention;

[0026] Figure 6 This is a top view of the heating sensing unit in this invention;

[0027] Figure 7 This is a schematic diagram of the heating unit in this invention;

[0028] Figure 8 This is a schematic diagram of the controller controlling the heating unit in this invention;

[0029] Figure 9 This is a schematic diagram of the exhaust temperature and electric heating control signals in this invention;

[0030] Figure 10 This is a schematic diagram of the brake energy recovery device in this invention. Detailed Implementation

[0031] The technical solution of the present invention will be further described below with reference to the accompanying drawings.

[0032] like Figure 1As shown, this invention is a urea decomposition device applied to an SCR system, used to decompose automotive urea injected into exhaust gas. The SCR system includes a controller 240 and, arranged sequentially along the exhaust gas flow direction, a diesel oxidation catalyst (DOC) DOC220, a cyclone particulate collector (CPC) CPC 200, and a diesel particulate filter (DPF) SDPF260 with SCR function. A first nitrogen oxide sensor 290, a first exhaust temperature sensor 295, a second exhaust temperature sensor 277, a second nitrogen oxide sensor 278, a third exhaust temperature sensor 286, and a differential pressure sensor 288 are connected to the controller 240 via signal lines 291, 294, 287, 285, 289, and 284, respectively. DOC220, CPC200, and SDPF260 are all connected to controller 240. CPC200 includes a cyclone generator 210 (SGD), a cyclone cylinder 212, a urea nozzle 275, a particle collection tank 213, a central airflow outlet pipe 215, and an airflow outlet pipe 211. The cyclone generator 210 is located downstream of DOC220, and the cyclone cylinder 212 is connected to the outlet of the cyclone generator 210. The exhaust gas generated by the engine enters SGD 210 after passing through DOC220, where a rotating airflow is generated. The particles in the cyclone airflow move towards the tank wall under the action of centrifugal force and eventually flow into the particle collection tank 213. The particle collection tank 213 is located at the lower opening of the cyclone cylinder 212, the central airflow outlet pipe 215 is located inside the cyclone cylinder 212, the heating sensor unit is located at the bottom of the particle collection tank, and the airflow outlet pipe is connected to the cyclone cylinder through the central airflow outlet pipe 215. Downstream of SGD 210, urea nozzle 275 is installed on the wall of cyclone cylinder 212. Urea nozzle 275 is controlled by controller 240 via signal line 281. The droplet particles sprayed from urea nozzle 275 rotate with the rotating airflow and undergo hydrolysis and pyrolysis. Large droplet particles that are not decomposed also flow into particle collection tank 213. The mixture of small particles with exhaust gas and ammonia (produced by urea decomposition) flows through central airflow outlet pipe 215 to airflow outlet pipe 211 and further enters SDPF 260. In this process, fine particles are filtered out, while ammonia reacts with nitrogen oxides in the exhaust gas to generate water and nitrogen. The treated exhaust gas flows out through SDPF 260. The urea nozzle 275 can be an electronically controlled nozzle, which includes a solenoid valve that controls the opening and closing of the nozzle. This solenoid valve can be controlled by the controller 240 via signal line 281. By controlling the opening time of the electronically controlled nozzle in a repetitive cycle, the flow rate of the urea solution flowing through the nozzle can be controlled (PWM method). Furthermore, by controlling the flow rate of the urea solution, the urea solution content (ammonia-nitrogen ratio) in the exhaust gas can be further controlled.

[0033] exist Figure 1 In the system shown, upstream of the DOC is a first nitrogen oxide sensor 290, electrically connected to the controller 240 via signal line 291. A first exhaust temperature sensor 295 reports exhaust temperature information upstream of the DOC to the controller 240 via signal line 294. Between the DOC 220 and SGD 210, a second exhaust temperature sensor 277 is electrically connected to the controller 240 via signal line 287, while a particulate matter sensor 214 in the particulate collection bin 213 is electrically connected to the controller 240 via signal line 282. Downstream of the SDPF, a second nitrogen oxide sensor 278 and a third exhaust temperature sensor 286 are electrically connected to the controller 240 via signal lines 285 and 289, respectively. The controller 240 can calculate and control the urea flow rate mixed into the exhaust gas flow using the exhaust nitrogen oxide concentration obtained from the first nitrogen oxide sensor 290, the exhaust temperature values ​​obtained from the second and third exhaust temperature sensors 277 and 286, and the exhaust gas flow rate value obtained from the engine ECU (not shown). The nitrogen and oxygen concentration of the tail gas obtained from the second nitrogen and oxygen sensor 278 can be used to diagnose whether the system is working properly (OBD).

[0034] Upstream and downstream of the SDPF 260, there are also air pipes connected to a differential pressure sensor 288, which is electrically connected to the controller 240 via a signal line 284. The pressure difference across the SDPF 260 obtained from the differential pressure sensor 288, as well as the upstream or downstream pressure value, can be used together with the exhaust gas flow rate to estimate the amount of soot deposited in the SDPF. When the amount of soot deposited exceeds a set value, the controller 240 triggers a regeneration process. During this process, the engine produces high-temperature exhaust gas and injects fuel. The fuel is further heated by oxidation at DOC 220, increasing the exhaust gas temperature, thereby using the high-temperature exhaust gas to remove the soot accumulated in the SDPF 260. The exhaust gas temperature values ​​and exhaust gas flow rates obtained from the first exhaust temperature sensor 295 and the second exhaust temperature sensor 277 can be used together to control the exhaust gas temperature during the regeneration process.

[0035] In the CPC 200 system, a vortex is first generated before the urea solution is injected. The generation of the vortex in the CPC 200 can be achieved using methods such as... Figure 2 and Figure 3 The blade structure shown is composed of an outer cylinder 310, an inner cylinder 315, and swirl blades 320. Figure 1In the system shown, the outer cylinder 310 is connected to the cyclone barrel 212, and the inner cylinder 315 is connected to the central airflow outlet pipe 215. Engine exhaust gas entering the CPC 200 first flows through the outer cylinder 310, where it is swirled by the swirl vanes 320. After passing through the cyclone barrel 212, the exhaust gas, having been filtered to remove large droplets and soot particles, flows through the central airflow outlet pipe 215 and the inner cylinder 315 into the airflow outlet pipe 211. In addition to filtering urea droplets, the CPC 200 can also filter large soot particles. This function allows the system to use a smaller particulate filter carrier, thereby reducing system cost and back pressure.

[0036] Figure 1 In the system, a heating sensing unit is located inside the particle collection tank 213, including a particle quantity sensor 214 and a heating device. The particle quantity sensor 214 is electrically connected to the controller 140 via signal line 282, and the heating device is electrically connected to the controller 240 via signal line 283. The particle quantity sensor detects the amount of particulate matter in the particle collection tank 213, while the heating device heats the particulate matter to pyrolyze and hydrolyze the urea components. In CPC200, large urea droplets are separated from the exhaust gas flow and then collected and concentrated for heating and decomposition. Since there is no strong airflow in the particle collection tank, the heating energy is mainly used to decompose urea rather than heat the exhaust gas, resulting in relatively low heating power and energy consumption.

[0037] To reduce the likelihood of urea droplets colliding with the cyclone cylinder wall under low discharge temperatures and forming crystals, a urea decomposition catalyst (hydrolysis catalyst) can be coated onto the cylinder wall. The cyclone cylinder can be made of materials such as stainless steel, while the urea decomposition catalyst can be a metal oxide catalyst (such as titanium dioxide TiO2 or zirconium dioxide ZrO2). In the CPC200, large urea particles collide with the cyclone cylinder wall. The catalyst on the cyclone cylinder wall prevents crystallization. Furthermore, the cyclone cylinder wall has a conical structure extending downwards, ensuring that fallen particles enter the particle collection bin instead of adhering to the wall. Many technologies can be used to fix the catalyst coating on the cyclone cylinder wall. Figure 4 In one embodiment shown, the inner wall of the cyclone cylinder 212 has a catalyst coating structure 142, which includes a well-shaped structure 143 formed by corrosion and a catalyst coating 144. The well-shaped structure 143 can better bond and secure the catalyst coating 144.

[0038] An implementation of the heating sensing unit is as follows: Figure 5 , Figure 6 and Figure 7As shown. In this embodiment, the heating sensing unit includes a housing 410, a lower base 430, an upper base 431, a bolt 411, a heating unit 420, a heat-conducting column 418, a catalyst coating 419, calcium carbonate particles 429, a particle quantity detection electrode one 415, and a particle quantity detection electrode two 416. Figure 5 , Figure 6 and Figure 7 As shown, in the heating sensing unit, the lower base 430 and the upper base 431 are fastened to the outer casing 410 with bolts 411. Corresponding grooves that can form a closed space are provided on the upper surface of the lower base 430 and the lower surface of the upper base 431. A heating unit 420 is located within the closed space between the lower base 430 and the upper base 431. This heating unit 420 consists of a heat conductor 441 and an electric heating element 442. The electric heating element 442 has an electrode 426 and an electrode 427. Electrodes 426 and 427 are provided with an outer insulator 425 and an insulator 428 to insulate them from the upper and lower bases 431 and 430. Electrodes 426 and 427 are electrically connected to the controller 240 via a signal line 283. A heat-conducting pillar 418 is located on the upper base 431, and a catalyst coating 419 is applied to the outer surfaces of the upper base 431 and the heat-conducting pillar 418. To solidify sulfur-containing compounds to protect the SCR, porous calcium carbonate particles 429 can be placed on the upper base 431. Particle quantity detection electrode one 415 and particle quantity detection electrode two 416 are inserted in the middle of the upper base 431 and lower base 430. The bottom of particle quantity detection electrode one 415 is provided with an outer insulator three 421 to insulate it from the upper and lower bases 431 and 430, while the electrode part contacts the particles. The bottom of particle quantity detection electrode two 416 is provided with an outer insulator four 423, and its lower electrode part can be covered with an outer insulator 417, with only the upper electrode contacting the particles. Particle quantity detection electrodes one 415 and particle quantity detection electrode two 416 are connected to the controller 240 via signal line 282.

[0039] Under high-sulfur oil conditions, sulfur oxides (mainly gaseous sulfur dioxide and sulfur-containing particulate matter) will be present in the exhaust gas. These sulfur oxides will enter the downstream catalyst and cause catalyst deactivation (catalyst poisoning). Sulfur oxides will form sulfate and sulfite ions in the urea solution droplets. These ions can be solidified by adding a collecting material to the particle collection tank 213. A commonly used collecting material is calcium carbonate, which can react with the sulfate and sulfite ions in the urea droplets flowing into the particle collection tank to form calcium sulfate. During maintenance, the cyclone separator and particle collection tank can be desulfurized to restore catalyst efficiency, and the calcium carbonate particles can be replaced. In this way, the CPC unit can filter sulfur, thereby effectively protecting the downstream catalyst. In addition, the exhaust gas after CPC 200 is fully mixed (the flow path is longer), and the detection of temperature and nitrogen oxides can better reflect the average value (no sampling mixer is required).

[0040] exist Figure 5 , Figure 6 and Figure 7 In the structure shown, the upper part of particle quantity detection electrode 2 416 is covered by an insulating layer 417. When the particle accumulation height exceeds the outer insulating layer, the impedance between particle quantity detection electrode 1 415 and particle quantity detection electrode 2 416 will change. By detecting this impedance change, it is possible to detect whether the particle quantity exceeds the limit. When the controller 240 detects that the particle quantity exceeds the limit, it can trigger a maintenance signal to prompt and request the user to perform maintenance on CPC 200.

[0041] During maintenance of the CPC 200, first shut down the engine, and then, after it has cooled down, remove the particle collection tank 213 from the cyclone separator 212 and clean out the collected material. After cleaning, further cleaning can be performed using a cleaning solution containing a weak acid, followed by drying and replacing the calcium carbonate particles. After maintenance, reinstall the particle collection tank 213 back into the system.

[0042] The impedance value Zs detected by particle quantity detection electrodes one and two is transmitted to the controller. The temperature value T277 measured by the second temperature sensor is transmitted to the controller, and the temperature value T286 measured by the third temperature sensor is transmitted to the controller. The controller compares the impedance value Zs with the threshold Thd_PLL. When the impedance value Zs is greater than the threshold Thd_PLL, it compares the temperature value T277 with the threshold Thd_STL. When T277 is less than Thd_STL, it outputs a start control signal for the heating unit. When T277 is not less than Thd_STL, it compares the temperature value T277 with another threshold Thd_STH. When T277 is greater than Thd_STH, it outputs a shut-off control signal for the heating unit. When the impedance value Zs is not greater than the threshold Thd_PLL, it outputs a shut-off control signal for the heating unit and also outputs a maintenance signal. In the CPC 200, electric heating can be used to raise the temperature of the urea droplets collected therein, causing them to hydrolyze and pyrolyze into ammonia. The electric heating of the heating unit can be controlled by a program running in the controller 240. A flowchart of a routine is shown below. Figure 8 As shown, this routine is an interrupt service routine with an interrupt cycle of T. After the program starts, it first compares the impedance value Zs (the magnitude of the impedance) measured by electrodes 415 and 416 with the threshold Thd_PLL. When Zs is greater than this threshold, it compares the temperature value T277 measured by the second temperature sensor 277 with the threshold Thd_STL. When T277 is less than Thd_STL, the heater control signal HTC is set to 1, electric heating is turned on, and then the program ends. If T277 is not less than Thd_STL, then T277 is compared with another threshold Thd_STH. If T277 is greater than Thd_STH, HTC is set to 0, electric heating is turned off; otherwise, the original HTC state is maintained. The program ends after completing this step. It then returns to the comparison of Zs and Thd_PLL. If Zs is not greater than Thd_PLL, the particulate matter collection amount exceeds the limit. In this case, HTC is set to 0, and then a flag bit F_PL is set to 1. The F_PL flag will trigger an alarm signal (such as an indicator light) to remind the user that the system needs maintenance.

[0043] In such Figure 8 Under the control of the example program, the electric heating control signal changes with the exhaust temperature value T277 as shown in the curve. Figure 6 As shown. Figure 9 In the diagram, curve 301 represents the exhaust gas temperature change curve, and curve 302 represents the HTC signal. When the exhaust gas temperature T277 is lower than THD_STL, the electric heater is activated; when it exceeds THD_STL, the electric heater is deactivated.

[0044] Figure 10In this system, the electrical heating energy for the heating sensor unit can be provided by regenerative braking. For frequent start-stop conditions, the exhaust gas temperature is low, resulting in more liquid droplet particles being collected. The braking energy is also greater, leading to frequent heating, which helps eliminate liquid droplets. For example... Figure 10 As shown, in one example, the brake energy recovery device includes a drive control unit 152 and a motor generator 155 mounted on axle 153. Axle 153 is connected to wheel 154, and motor generator 155 is electrically connected to control unit 240 via signal line (wire group) 151. When the vehicle brakes, motor generator 155 enters generator mode and is driven by axle 153. The electricity generated by motor generator 155 is applied to a heating sensing unit for heating via signal line 151, controller 240, and signal line 283.

[0045] The heating time of the heating sensing unit is related to the exhaust temperature and flow rate. Lower exhaust temperatures and smaller flow rates result in larger droplet particles due to insufficient energy for evaporating the urea solution and hydrolyzing and pyrolyzing it. This increases the amount of droplets falling into the collection bucket 212, and the increased droplet flow requires more heating energy to remove them. During vehicle operation, low exhaust temperatures and flow rates are often caused by frequent starts and stops. Frequent starts and stops increase battery consumption (especially when charging power is low). Excessive energy consumption for heating at this time will affect battery storage. Using braking energy for heating can fully utilize the increased brake energy recovery during frequent starts and stops, balancing the heating energy consumption. (The more frequent the braking, the more brake energy is recovered, resulting in more heating energy and a greater ability to remove droplet particles). Furthermore, brake heating is an energy recovery process and does not increase fuel consumption.

Claims

1. A urea decomposition device with a cyclone generator, characterized in that: The system includes a cyclone particulate collector and a controller. The cyclone particulate collector includes a cyclone generator, a cyclone cylinder connected to the outlet of the cyclone generator, a urea nozzle interface located on the cyclone cylinder and downstream of the cyclone generator, a particle collection bucket located at the lower opening of the cyclone cylinder, a heating sensing unit located at the bottom of the particle collection bucket, and an air outlet pipe connected to the cyclone cylinder. The heating sensing unit is electrically connected to the controller. The exhaust gas enters the cyclone generator and generates a rotating airflow. Urea droplets sprayed from the urea nozzle enter the rotating airflow through the urea nozzle interface and rotate and decompose. Large, undecomposed urea droplets separate from the main airflow and then flow into the particle collection bucket. The mixture of small urea droplets, ammonia gas generated from decomposition, and exhaust gas flows out through the air outlet pipe. The heating sensing unit includes a particle quantity sensor for detecting particulate matter and a heating device for heating urea droplets, wherein the particle quantity sensor and the heating device are electrically connected to the controller. The heating device is equipped with a heating unit, which includes a heat conductor and an electric heating element. The electric heating element is electrically connected to and controlled by the controller. The particle quantity sensor includes two detection electrodes, and the controller includes a reactance measurement circuit for measuring the impedance change between the two particle quantity detection electrodes. The controller controls the heating unit based on the impedance change measured by the reactance measurement circuit. The impedance value Zs measured by the reactance measurement circuit is transmitted to the controller, and the exhaust gas temperature value T277 of the cyclone particulate collector is transmitted to the controller. The controller compares the impedance value Zs with a threshold Thd_PLL. When the impedance value Zs is greater than the threshold Thd_PLL, it compares the exhaust gas temperature value T277 with a threshold Thd_STL. When T277 is less than Thd_STL, it outputs a start control signal to the heating unit. When T277 is not less than Thd_STL, it compares the temperature value T277 with another threshold Thd_STH. When T277 is greater than Thd_STH, it outputs a shut-off control signal to the heating unit. When the impedance value Zs is not greater than the threshold Thd_PLL, it outputs a shut-off control signal to the heating unit.

2. The urea decomposition device with a cyclone generator according to claim 1, characterized in that: The cyclone cylinder includes an outer cylinder and an inner cylinder that are concentrically arranged, as well as swirl blades located between the outer cylinder and the inner cylinder. Engine exhaust gas first enters the outer cylinder and generates a swirling flow through the swirl blades. A mixture of small urea droplets, ammonia gas produced by decomposition, and exhaust gas enters the air outlet pipe through the inner cylinder and flows out of the urea decomposition device.

3. The urea decomposition device with a cyclone generator according to claim 2, characterized in that: The inner wall of the cyclone cylinder is coated with a catalyst coating structure, which includes a catalyst coating for urea hydrolysis.

4. The urea decomposition device with a cyclone generator according to claim 1, characterized in that: The upper surface of the heating device is coated with a catalyst coating that comes into contact with the urea flowing into the particle collection tank.

5. The urea decomposition device with a cyclone generator according to claim 1, characterized in that: It also includes a brake kinetic energy recovery device electrically connected to the controller, the brake kinetic energy recovery device including a transmission device connected to the wheel and a kinetic energy to electrical energy conversion device connected to the transmission device; the controller uses the electrical energy generated by the brake kinetic energy recovery device to control the heating unit.

6. The urea decomposition device with a cyclone generator according to claim 1, characterized in that: The particle collection bucket contains a collecting substance for sulfate and sulfite ions, which reacts with compounds containing sulfate and sulfite ions to form salts.

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