Post-treatment SCR (Selective Catalytic Reduction) two-way urea injection control method, device and system and engineering equipment

Abstract

The invention relates to the technical field of SCR aftertreatment, and provides an aftertreatment SCR two-way urea injection control method, device and system and engineering equipment. The method comprises the following steps that the starting temperature of an engine and the current temperature of a preceding-stage SCR are obtained; when it is determined that the starting temperature of the engine is smaller than the preset temperature, the engine is cold-started; when it is determined that the starting temperature of the engine is not smaller than the preset temperature, the engine is hot-started; when it is determined that the engine is in cold start and the current temperature of a preceding-stage SCR reaches a first spraying starting temperature, a preceding-stage nozzle starts urea spraying, and the first spraying starting temperature is the temperature at which urea starts to be hydrolyzed; and when it is determined that the engine is in hot start and the current temperature of the preceding-stage SCR reaches the second injection starting temperature, the preceding-stage nozzle starts urea injection. Thus, by distinguishing the cold-state working condition and the hot-state working condition of the engine, when the current temperature of the preceding-stage SCR reaches the urea hydrolysis starting temperature, the preceding-stage nozzle starts urea injection, and nitrogen and oxygen emission under the cold start working condition of the engine can be reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of SCR post-treatment, and in particular to a post-treatment SCR two-way urea injection control method, device, system and engineering equipment. Background Art

[0002] Selective Catalytic Reduction (SCR) technology is an efficient method to reduce nitrogen oxides (NOx) emissions from diesel engines. With the increasing global awareness of environmental protection and the increasingly stringent automobile exhaust emission standards set by governments around the world, SCR technology has been widely used in diesel engine vehicles such as heavy trucks, buses and non-road mobile machinery.

[0003] In order to meet emission requirements, most manufacturers currently use the technical route of installing two SCRs in the exhaust after-treatment system for treatment. SCR is the core unit in the after-treatment system. The NH3 produced by the high-temperature hydrolysis of the quantitatively injected urea reacts with the NOx in the exhaust gas on the surface of the SCR system catalyst, thereby achieving the purpose of emission reduction.

[0004] However, the existing SCR urea injection temperature is a fixed calibration value. When the engine is cold-started, the exhaust temperature is low and cannot reach the urea injection temperature, resulting in higher cold nitrogen oxide emissions. Summary of the invention

[0005] The present invention provides a post-treatment SCR two-way urea injection control method, device, system and engineering equipment to solve the defect of high nitrogen oxide emission during engine cold start in the prior art, and can reduce the nitrogen oxide emission during engine cold start without increasing hardware cost.

[0006] The present invention provides a post-processing SCR two-way urea injection control method, comprising the following steps: Get the engine startup temperature and the current temperature of the front-stage SCR; When it is determined that the starting temperature of the engine is less than a preset temperature, the engine is cold started; when it is determined that the starting temperature of the engine is not less than the preset temperature, the engine is hot started; When it is determined that the engine is cold started and the current temperature of the front-stage SCR reaches a first start-injection temperature, the front-stage nozzle starts urea injection, and the first start-injection temperature is a temperature at which urea begins to hydrolyze; When it is determined that the engine is hot started and the current temperature of the front-stage SCR reaches a second injection start temperature, the front-stage nozzle starts urea injection.

[0007] A post-treatment SCR two-way urea injection control method provided by the present invention also includes the following steps: Get the current temperature of the subsequent SCR; When it is determined that the current temperature of the rear-stage SCR reaches the third injection start temperature, the rear-stage nozzle starts urea injection.

[0008] A post-treatment SCR two-way urea injection control method provided by the present invention also includes the following steps: Determine the target urea injection amount; When it is determined that the target urea injection amount is not greater than the maximum urea injection amount under the condition of limiting crystallization, the target urea injection amount is the actual urea injection amount; When it is determined that the target urea injection amount is greater than the maximum urea injection amount under the condition of limiting crystallization, the maximum urea injection amount under the condition of limiting crystallization is the actual urea injection amount.

[0009] According to a post-treatment SCR two-way urea injection control method provided by the present invention, the target urea injection amount is determined by the front-stage SCR temperature and the exhaust gas amount.

[0010] According to a post-treatment SCR two-way urea injection control method provided by the present invention, the target urea injection amount of the front-stage SCR is determined by the following formula: The target urea injection amount of the pre-stage SCR = the content of nitrogen oxides upstream of the pre-stage SCR × the conversion coefficient of nitrogen oxides to ammonia × SCR model efficiency × the conversion coefficient of ammonia to urea.

[0011] According to a post-treatment SCR two-way urea injection control method provided by the present invention, the target urea injection amount of the post-stage SCR is determined by the following formula: The target urea injection amount of the rear-stage SCR = (the basic urea injection amount of the rear-stage SCR + the ammonia storage adjustment urea injection amount of the rear-stage SCR) × the ammonia to urea conversion coefficient; The basic urea injection amount of the post-stage SCR = the content of nitrogen oxides upstream of the post-stage SCR × the conversion coefficient of nitrogen oxides to ammonia × SCR model efficiency; The ammonia storage adjustment urea injection amount of the rear-stage SCR=(rear-stage SCR target ammonia storage amount-rear-stage SCR model ammonia storage amount) / ammonia storage adjustment time.

[0012] According to a post-treatment SCR two-way urea injection control method provided by the present invention, the starting temperature of the engine is determined by the engine oil temperature and the engine water temperature.

[0013] The present invention also provides a post-processing SCR two-way urea injection control device, comprising: An acquisition module is used to obtain the starting temperature of the engine and the current temperature of the front-stage SCR; A storage module for storing operating parameters of the engine and the front-stage SCR; The processing module determines that when the starting temperature of the engine is less than a preset temperature, the engine is a cold start; when the starting temperature of the engine is not less than the preset temperature, the engine is a hot start; when it is determined that the engine is a cold start and the current temperature of the front-stage SCR reaches a first start-up temperature, the front-stage nozzle starts urea injection, and the first start-up temperature is the temperature at which urea begins to hydrolyze; when it is determined that the engine is a hot start and the current temperature of the front-stage SCR reaches a second start-up temperature, the front-stage nozzle starts urea injection.

[0014] The present invention also provides a post-treatment SCR two-way urea injection system, comprising: a data acquisition module and a turbine, a front-stage SCR, a DOC, a DPF and a rear-stage SCR connected in sequence, a front-stage nozzle is arranged between the turbine and the front-stage SCR, and a rear-stage nozzle is arranged between the DPF and the rear-stage SCR; The data acquisition module includes a temperature sensor and a NOx sensor. The temperature sensor is used to collect the temperature of the engine, the front-stage SCR and the rear-stage SCR; the NOx sensor is used to collect the NOx content in the exhaust gas entering the front-stage SCR and the rear-stage SCR; It also includes the above-mentioned post-processing SCR two-way urea injection control device.

[0015] The present invention also provides an engineering device, comprising the above-mentioned post-processing SCR two-way urea injection system.

[0016] An electronic device comprises a memory, a processor and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, any one of the above-mentioned post-treatment SCR two-way urea injection control methods is implemented.

[0017] The present invention also provides a non-transitory computer-readable storage medium on which a computer program is stored. When the computer program is executed by a processor, the post-treatment SCR two-way urea injection control method as described in any one of the above is implemented.

[0018] The present invention also provides a computer program product, comprising a computer program, wherein when the computer program is executed by a processor, the post-treatment SCR two-way urea injection control method as described above is implemented.

[0019] Beneficial effects: 1. By distinguishing between the cold and hot conditions of the engine, when the current temperature of the front-stage SCR reaches the temperature at which urea begins to hydrolyze, the front-stage nozzle starts to spray urea. At this time, the urea solution is hydrolyzed into ammonia in the exhaust pipe. The ammonia reacts with the NOx discharged by the engine inside the front-stage SCR catalyst, thereby reducing the nitrogen oxide emissions under the cold start condition of the engine.

[0020] 2. The front-stage SCR is mainly used to reduce low-temperature NOx. It does not need to participate in the closed loop and only uses urea injection based on the target efficiency. Urea injection based on ammonia storage is not required. This saves test bench costs and simplifies calibration time.

[0021] 3. Determining the target urea injection amount based on the pre-SCR temperature and the exhaust gas volume, and determining the actual injection amount based on the target urea injection amount and the maximum urea injection amount under the condition of limiting crystallization can reduce the risk of urea crystallization in the pre-SCR at low temperatures. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the present invention or the prior art, a brief introduction will be given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0023] Figure 1 It is a structural schematic diagram of the post-processing SCR two-way urea injection system provided by the present invention.

[0024] Figure 2 It is a schematic flow chart of the post-processing SCR two-way urea injection method provided by the present invention.

[0025] Figure 3 It is a structural schematic diagram of the electronic device provided by the present invention.

[0026] Reference numerals: 1. Turbine; 2. Front-stage SCR; 3. DOC; 4. DPF; 5. Rear-stage SCR; 6. Front-stage nozzle; 7. Rear-stage nozzle; 810. Processor; 820. Communication interface; 830. Memory; 840. Communication bus. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] In order to facilitate understanding of the post-treatment SCR two-way urea injection control method, device, system and engineering equipment provided by the present invention, its application background is first introduced. SCR technology is a method for efficiently reducing nitrogen oxides (NOx) emissions from diesel engines.

[0029] In order to meet emission requirements, most manufacturers currently use the technical route of installing two SCRs in the exhaust after-treatment system for treatment. SCR is the core unit in the after-treatment system. The NH3 produced by the high-temperature hydrolysis of the quantitatively injected urea reacts with the NOx in the exhaust gas on the surface of the SCR system catalyst, thereby achieving the purpose of emission reduction.

[0030] However, the existing SCR urea injection temperature is a fixed calibration value. When the engine is cold-started, the exhaust temperature is low and cannot reach the urea injection temperature, resulting in higher cold nitrogen oxide emissions.

[0031] In view of the above problems, the present invention provides a post-treatment SCR two-way urea injection control method, device, system and engineering equipment, which can reduce nitrogen oxide emissions during engine cold start without increasing hardware costs.

[0032] Combine the following Figure 1-Figure 3 The present invention describes the post-treatment SCR two-way urea injection control method, device, system and engineering equipment.

[0033] In the embodiment of the present invention, refer to Figure 1 The post-treatment SCR (Selective Catalytic Reduction) two-way urea injection system adopts a dual-injection SCR system, which includes a turbine 1, a front-stage SCR2, a DOC3 (diesel oxidation catalyst), a DPF4 (diesel particulate filter) and a rear-stage SCR5 connected in sequence.

[0034] Among them, the front-stage SCR2 adopts a close-coupled SCR (closed couple Selective Catalytic Reduction) system, which is located closer to the turbine 1, so the response speed is faster. Since the exhaust temperature at the exhaust port is higher, it is conducive to the rapid decomposition of urea aqueous solution and the generation of ammonia, and can enhance the engine's ability to remove NOx in a cold state. The rear-stage SCR5 is located far away from the turbine 1 and is used to remove most of the NOx downstream.

[0035] DOC3 can provide a strong oxidation effect, which can oxidize carbon monoxide and hydrogen into carbon dioxide and water, and oxidize part of nitrogen monoxide into nitrogen dioxide, thereby increasing the exhaust temperature.

[0036] DPF4 is used to filter solid particulate matter (mainly carbon soot) in engine exhaust, which can reduce the particulate matter in the exhaust gas and achieve the purpose of reducing particulate matter emissions.

[0037] A front-stage nozzle 6 is provided between the turbine 1 and the front-stage SCR 2 , and a rear-stage nozzle 7 is provided between the DPF 4 and the rear-stage SCR 5 .

[0038] The post-treatment SCR two-way urea injection system also includes a data acquisition module, which includes a temperature sensor and a NOx sensor. The temperature sensor can collect the temperature of the engine, the front-stage SCR2 and the rear-stage SCR5, and the NOx sensor can collect the NOx content in the exhaust gas entering the front-stage SCR2 and the rear-stage SCR5.

[0039] Figure 2 It is a flow chart of the post-treatment SCR two-way urea injection control method provided by the present invention. The method can be applied to a vehicle controller, such as an ECU (Electronic Control Unit, a vehicle computer), etc. The ECU can complete the acquisition and storage of the above-mentioned sensor parameters, as well as the storage and transmission of the limit values ​​corresponding to each parameter.

[0040] Reference Figure 2 The post-treatment SCR two-way urea injection control method includes the following steps: Step 10: Obtain the starting temperature of the engine and the current temperature of the front-stage SCR2.

[0041] As a complex thermodynamic system, the temperature of the engine is affected by many factors. The engine oil temperature and water temperature can be regarded as representatives of the temperatures of different parts of the engine. Therefore, the engine temperature can be indirectly reflected by monitoring the engine oil temperature and water temperature.

[0042] There are many optional ways to calculate the engine temperature. For example, the weighted average method can be used to estimate the engine temperature by the weight of the heat capacity distribution of oil and water in the engine cooling system. Model predictive control can also be used to predict the engine temperature based on the historical data and changing trends of oil and water temperatures. Empirical formulas can also be used to estimate the engine temperature based on the specific model and design of the engine using empirical formulas provided by the manufacturer.

[0043] Of course, the engine includes but is not limited to the temperature calculation methods listed above, and other methods are also applicable. The specific method can be selected according to actual needs and working conditions, and no specific limitation is made in the embodiments of the present invention.

[0044] The current temperature of the front-stage SCR2 can be collected through a temperature sensor. Specifically, the current temperature of the front-stage SCR2 can be collected through a built-in temperature sensor; the temperature upstream of the front-stage SCR2, that is, the intake temperature, can also be collected as the current temperature of the front-stage SCR2; the upstream temperature can also be collected, and then this temperature value is input into the SCR catalyst carrier temperature model to obtain the current temperature value of the front-stage SCR2.

[0045] It is understandable that the front-stage SCR2 is not limited to the above-mentioned temperature collection method, and other temperature collection methods that can collect the temperature of the front-stage SCR2 are applicable. The specific selection can be based on actual needs and working conditions, and no specific limitation is made in the embodiments of the present invention.

[0046] Step 11: When it is determined that the starting temperature of the engine is less than a preset temperature, the engine is cold started; when it is determined that the starting temperature of the engine is not less than the preset temperature, the engine is hot started.

[0047] Specifically, different tests or studies may make different provisions for the preset temperature of the engine according to specific purposes or conditions, which means that in some cases, the preset temperature may be different, depending on the specific requirements of the test or the goals of the study. For example, the cold WHTC in the cold and hot WHTC (Worldwide Harmonized Transient Cycle) condition and the start stage in the cold PEMS (Portable Emissions Measurement Systems) test all start at an engine temperature of around 30 degrees Celsius.

[0048] As a specific embodiment of the present invention, when the engine starting temperature is 40 degrees Celsius, the engine is cold started, and when the engine starting temperature is not less than 40 degrees Celsius, the engine is hot started. By comparing the engine starting temperature with the preset temperature, it is determined whether the engine is cold started or hot started.

[0049] Step 12: When it is determined that the engine is cold started and the current temperature of the front-stage SCR2 reaches a first start-injection temperature, the front-stage nozzle 6 starts urea injection, and the first start-injection temperature is a temperature at which urea begins to hydrolyze.

[0050] When the current temperature of the front-stage SCR2 reaches the temperature at which urea begins to hydrolyze, the front-stage nozzle 6 starts urea injection. At this time, the urea solution is hydrolyzed into ammonia in the exhaust pipe. The ammonia reacts with the NOx exhausted by the engine inside the front-stage SCR2 catalyst, thereby reducing nitrogen oxide emissions under engine cold start conditions.

[0051] As a specific embodiment of the present invention, the first injection temperature may be set to 130° C. to 140° C., and the specific temperature is determined during SCR calibration.

[0052] Step 13: When it is determined that the engine is hot started and the current temperature of the front-stage SCR2 reaches the second injection start temperature, the front-stage nozzle 6 starts urea injection.

[0053] In the engine hot start mode, when the current temperature of the front stage SCR2 reaches the second start-up temperature, the front stage nozzle 6 starts urea injection. At this time, the rear stage SCR5 carrier is mainly used for catalytic reduction of NOx, and the front stage SCR2 mainly plays an auxiliary role.

[0054] As a specific embodiment of the present invention, the second start-up temperature can be set to 170° C. to 180° C., and the specific temperature is determined in the SCR calibration.

[0055] Step 14: Obtain the current temperature of the rear-stage SCR5, and when it is determined that the current temperature of the rear-stage SCR5 reaches the third injection start temperature, the rear-stage nozzle 7 starts urea injection.

[0056] After the engine is started, as the exhaust temperature gradually increases, when the current temperature of the rear-stage SCR5 reaches the third start-up temperature, the rear-stage nozzle 7 injects urea to ensure the effectiveness of the entire system in NOx reduction.

[0057] The current temperature of the rear-stage SCR5 can be collected through a temperature sensor. Specifically, the current temperature of the rear-stage SCR5 can be collected through a built-in temperature sensor; the temperature upstream of the rear-stage SCR5, that is, the intake temperature, can also be collected as the current temperature of the rear-stage SCR5; the upstream temperature can also be collected, and then this temperature value is input into the SCR catalyst carrier temperature model to obtain the current temperature value of the rear-stage SCR5.

[0058] It is understandable that the post-stage SCR5 is not limited to the above-mentioned temperature collection method, and other temperature collection methods that can collect the temperature of the post-stage SCR5 are applicable. The specific method can be selected according to actual needs and working conditions, and is not specifically limited in the embodiments of the present invention.

[0059] In one embodiment of the present invention, in order to reduce the risk of urea crystallization, the post-processing SCR two-way urea injection control method further includes the following steps: Step 100: determining a target urea injection amount.

[0060] Specifically, the target urea injection amount of the pre-stage SCR2 is determined by the pre-stage SCR2 temperature and the exhaust gas amount.

[0061] More specifically, the target urea injection amount of the front-stage SCR2 is determined by the following formula: The target urea injection amount of the front-stage SCR2 = the target ammonia injection amount of the front-stage SCR2 × the conversion coefficient of ammonia to urea = the content of nitrogen oxides upstream of the front-stage SCR2 × the conversion coefficient of nitrogen oxides to ammonia × the SCR model efficiency × the conversion coefficient of ammonia to urea.

[0062] Among them, the upstream NO XIt represents the amount of NOx in the exhaust gas emitted from the engine exhaust port. It is the basis for determining how much urea is needed to effectively reduce NOx emissions. It can be specifically tested through NOx.

[0063] NO X The NH3 conversion factor reflects the amount of ammonia (NH3) required to effectively react with NOx. Different NOx compounds may require different proportions of NH3 for complete reaction. The specific reaction equation is shown below: 4NO+4NH3+O2→4N2+6H2O; 6NO2+8NH3→7N2+12H2O; 2NO2+4NH3+O2→3N2+6H2O.

[0064] SCR model efficiency refers to the actual effect of the SCR system in treating nitrogen oxides (NOx) in diesel engine exhaust, that is, under given conditions, what proportion of NOx can be converted into harmless nitrogen and water. The SCR model efficiency is affected by many factors, including but not limited to temperature, catalyst type, air velocity, moisture and sulfide, system design, etc. Therefore, the SCR model efficiency can be determined according to actual operating conditions.

[0065] Therefore, the target ammonia injection amount of the front-stage SCR2 = the content of nitrogen oxides upstream of the front-stage SCR2 × the conversion coefficient of nitrogen oxides to ammonia × the SCR model efficiency.

[0066] The NH3 to urea conversion coefficient reflects how much ammonia can be produced per unit mass of urea, which is crucial for accurately calculating the amount of urea required. The standard equation for the urea hydrolysis reaction is: (NH2)2CO+H2O→2NH3+CO2; however, in actual applications, the conversion coefficient of NH3 to urea is often affected by factors such as temperature, so the conversion coefficient of NH3 to urea can be determined according to actual working conditions.

[0067] Finally, the target urea injection amount of the front-stage SCR2 = the content of nitrogen oxides upstream of the front-stage SCR2 × the conversion coefficient of nitrogen oxides to ammonia × the SCR model efficiency × the conversion coefficient of ammonia to urea.

[0068] The target urea injection amount of the post-stage SCR5 is calculated by the following formula: The target urea injection amount of the rear-stage SCR5 = (the basic urea injection amount of the rear-stage SCR5 + the ammonia storage adjustment urea injection amount of the rear-stage SCR5) × the ammonia to urea conversion coefficient.

[0069] Among them, the basic urea injection amount of the rear-stage SCR5 = the content of nitrogen oxides upstream of the rear-stage SCR5 × the conversion coefficient of nitrogen oxides to ammonia × SCR model efficiency.

[0070] The ammonia storage adjustment urea injection amount of the rear-stage SCR5 = (the target ammonia storage amount of the rear-stage SCR5 - the ammonia storage amount of the rear-stage SCR model) / ammonia storage adjustment time.

[0071] Through the above technical solution, the target urea injection amounts of the front-stage SCR2 and the rear-stage SCR5 can be determined.

[0072] Step 101: When it is determined that the target urea injection amount is not greater than the maximum urea injection amount under the condition of limiting crystallization, the target urea injection amount is the actual urea injection amount.

[0073] Specifically, in the diesel engine SCR system, the maximum urea injection amount under the condition of limiting crystallization is an important consideration. If the urea injection amount is too large and exceeds the maximum allowable value under current conditions, the excess urea solution will accumulate in the exhaust system, forming crystals and causing blockage. The maximum urea injection amount needs to be determined by comprehensively considering factors such as temperature, urea solution concentration, exhaust flow, and system design. When the target urea injection amount is not greater than the maximum urea injection amount under the condition of limiting crystallization, it indicates that the risk of urea crystallization is relatively low when the urea injection is carried out according to the target urea injection amount. Therefore, the target urea injection amount can be used as the actual urea injection amount.

[0074] Specifically, when the engine is started as a cold engine, the maximum ammonia injection amount limited by the front-stage crystallization boundary is obtained by interpolating the cold engine start crystallization boundary map based on the temperature and exhaust gas volume of the front-stage SCR2; when the engine is started as a hot engine, the maximum ammonia injection amount limited by the front-stage crystallization boundary map is obtained by interpolating the hot engine start crystallization boundary map based on the temperature and exhaust gas volume of the front-stage SCR2; the maximum urea injection amount limited by the hot engine start crystallization boundary map is greater than the maximum urea injection amount limited by the cold engine start crystallization boundary map.

[0075] Step 102: When it is determined that the target urea injection amount is greater than the maximum urea injection amount under the condition of limiting crystallization, the maximum urea injection amount under the condition of limiting crystallization is the actual urea injection amount.

[0076] When the target urea injection amount is greater than the maximum urea injection amount under the condition of limiting crystallization, it indicates that there is a risk of crystallization when urea is injected according to the target urea injection amount. Therefore, the maximum urea injection amount under the condition of limiting crystallization can be used as the actual urea injection amount.

[0077] By adopting the above technical solution, the risk of urea crystallization in the front-stage SCR2 at low temperatures can be reduced. The front-stage SCR2 is mainly used to reduce low-temperature NOx and does not need to participate in a closed loop. It only needs urea injection based on target efficiency, and does not need urea injection based on ammonia storage. This saves bench costs during testing and simplifies calibration time.

[0078] The post-treatment SCR two-way urea injection control device provided by the present invention is described below. The post-treatment SCR two-way urea injection control device described below and the post-treatment SCR two-way urea injection method described above can be referred to each other.

[0079] A post-processing SCR two-way urea injection control device, comprising: An acquisition module is used to acquire the starting temperature of the engine and the current temperature of the front-stage SCR2; A storage module, used to store the operating parameters of the engine and the front-stage SCR2; The processing module determines that when the starting temperature of the engine is less than the preset temperature, the engine is a cold start; when the starting temperature of the engine is not less than the preset temperature, the engine is a hot start; when it is determined that the engine is a cold start and the current temperature of the front-stage SCR2 reaches the first start-up temperature, the front-stage nozzle 6 starts urea injection, and the first start-up temperature is the temperature at which urea begins to hydrolyze; when it is determined that the engine is a hot start and the current temperature of the front-stage SCR2 reaches the second start-up temperature, the front-stage nozzle 6 starts urea injection.

[0080] On the other hand, the present invention also provides a post-processing SCR two-way urea injection system, comprising: a data acquisition module and a turbine 1, a front-stage SCR2, a DOC3, a DPF4 and a rear-stage SCR5 connected in sequence, a front-stage nozzle 6 is arranged between the turbine 1 and the front-stage SCR2, and a rear-stage nozzle 7 is arranged between the DPF4 and the rear-stage SCR5; the data acquisition module comprises a temperature sensor and a NOx sensor, the temperature sensor is used to collect the temperature of the engine, the front-stage SCR2 and the rear-stage SCR5; the NOx sensor is used to collect the NOx content in the exhaust gas entering the front-stage SCR2 and the rear-stage SCR5; and also includes the above-mentioned post-processing SCR two-way urea injection control device.

[0081] On the other hand, the present invention further provides an engineering equipment, comprising the above-mentioned post-treatment SCR two-way urea injection system.

[0082] Specifically, engineering equipment includes but is not limited to heavy trucks, trailers, excavators, anchor diggers, bulldozers, road rollers, concrete pump trucks and other operating vehicles, or tower cranes, construction elevators, material hoists and other mechanical operating equipment.

[0083] In another aspect, the present invention further provides an electronic device, Figure 3 An example of a physical structure diagram of an electronic device is shown in FIG. Figure 3As shown, the electronic device may include: a processor 810, a communication interface 820, a memory 830 and a communication bus 840, wherein the processor 810, the communication interface 820 and the memory 830 communicate with each other through the communication bus 840. The processor 810 may call the logic instructions in the memory 830 to execute the post-processing SCR two-way urea injection method, the method comprising: obtaining the engine startup temperature and the current temperature of the front-stage SCR2; when it is determined that the engine startup temperature is less than the preset temperature, the engine is a cold start; when it is determined that the engine startup temperature is not less than the preset temperature, the engine is a hot start; when it is determined that the engine is a cold start and the current temperature of the front-stage SCR2 reaches the first start-up temperature, the front-stage nozzle 6 starts urea injection, the first start-up temperature is the temperature at which urea starts to hydrolyze; when it is determined that the engine is a hot start and the current temperature of the front-stage SCR2 reaches the second start-up temperature, the front-stage nozzle 6 starts urea injection.

[0084] In addition, the logic instructions in the above-mentioned memory 830 can be implemented in the form of a software functional unit and can be stored in a computer-readable storage medium when it is sold or used as an independent product. Based on this understanding, the technical solution of the present invention is essentially or the part that contributes to the prior art or the part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk and other media that can store program codes.

[0085] On the other hand, the present invention also provides a computer program product, which includes a computer program, which can be stored on a non-transitory computer-readable storage medium. When the computer program is executed by a processor, the computer can execute the post-processing SCR two-way urea injection method provided by the above methods, and the method includes: obtaining the starting temperature of the engine and the current temperature of the front-stage SCR2; when it is determined that the starting temperature of the engine is less than a preset temperature, the engine is a cold start; when it is determined that the starting temperature of the engine is not less than the preset temperature, the engine is a hot start; when it is determined that the engine is a cold start and the current temperature of the front-stage SCR2 reaches a first start-up temperature, the front-stage nozzle 6 starts urea injection, and the first start-up temperature is the temperature at which urea begins to hydrolyze; when it is determined that the engine is a hot start and the current temperature of the front-stage SCR2 reaches a second start-up temperature, the front-stage nozzle 6 starts urea injection.

[0086] On the other hand, the present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, which is implemented when the processor executes the post-processing SCR two-way urea injection method provided by the above methods, the method comprising: obtaining the starting temperature of the engine and the current temperature of the front-stage SCR2; when it is determined that the starting temperature of the engine is less than a preset temperature, the engine is a cold start; when it is determined that the starting temperature of the engine is not less than the preset temperature, the engine is a hot start; when it is determined that the engine is a cold start and the current temperature of the front-stage SCR2 reaches a first start-up temperature, the front-stage nozzle 6 starts urea injection, the first start-up temperature being the temperature at which urea begins to hydrolyze; when it is determined that the engine is a hot start and the current temperature of the front-stage SCR2 reaches a second start-up temperature, the front-stage nozzle 6 starts urea injection.

[0087] The device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without paying creative labor.

[0088] Through the description of the above implementation methods, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus a necessary general hardware platform, and of course, can also be implemented by hardware. Based on this understanding, the above technical solution is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0089] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A post-treatment SCR two-way urea injection control method, characterized in that: The following steps are involved: Get the engine startup temperature and the current temperature of the front-stage SCR; When it is determined that the starting temperature of the engine is less than a preset temperature, the engine is cold started; When it is determined that the starting temperature of the engine is not less than the preset temperature, the engine is hot started; When it is determined that the engine is cold started and the current temperature of the front-stage SCR reaches a first start-injection temperature, the front-stage nozzle starts urea injection, and the first start-injection temperature is a temperature at which urea begins to hydrolyze; When it is determined that the engine is hot started and the current temperature of the front-stage SCR reaches a second injection start temperature, the front-stage nozzle starts urea injection.

2. The post-treatment SCR two-way urea injection control method according to claim 1, characterized in that: The following steps are also included: Get the current temperature of the subsequent SCR; When it is determined that the current temperature of the rear-stage SCR reaches the third injection start temperature, the rear-stage nozzle starts urea injection.

3. The post-processing SCR two-way urea injection control method according to claim 1, characterized in that: The following steps are also included: Determine the target urea injection amount; When it is determined that the target urea injection amount is not greater than the maximum urea injection amount under the condition of limiting crystallization, the target urea injection amount is the actual urea injection amount; When it is determined that the target urea injection amount is greater than the maximum urea injection amount under the condition of limiting crystallization, the maximum urea injection amount under the condition of limiting crystallization is the actual urea injection amount.

4. The post-processing SCR two-way urea injection control method according to claim 3 is characterized in that: The target urea injection amount is determined by the pre-SCR temperature and the exhaust gas amount.

5. The post-processing SCR two-way urea injection control method according to claim 4, characterized in that: The target urea injection amount of the front-stage SCR is determined by the following formula: The target urea injection amount of the pre-stage SCR = the content of nitrogen oxides upstream of the pre-stage SCR × the conversion coefficient of nitrogen oxides to ammonia × SCR model efficiency × the conversion coefficient of ammonia to urea.

6. The post-processing SCR two-way urea injection control method according to claim 3, characterized in that: The target urea injection amount of the post-stage SCR is determined by the following formula: The target urea injection amount of the post-stage SCR = (the basic urea injection amount of the post-stage SCR + the ammonia storage adjustment urea injection amount of the post-stage SCR) × the ammonia to urea conversion coefficient; The basic urea injection amount of the post-stage SCR = the content of nitrogen oxides upstream of the post-stage SCR × the conversion coefficient of nitrogen oxides to ammonia × SCR model efficiency; The ammonia storage adjustment urea injection amount of the rear-stage SCR=(rear-stage SCR target ammonia storage amount-rear-stage SCR model ammonia storage amount) / ammonia storage adjustment time.

7. A post-treatment SCR two-way urea injection control device, characterized in that: include: An acquisition module is used to obtain the starting temperature of the engine and the current temperature of the front-stage SCR; A storage module for storing operating parameters of the engine and the front-stage SCR; The processing module determines that when the starting temperature of the engine is less than a preset temperature, the engine is cold started; When it is determined that the starting temperature of the engine is not less than the preset temperature, the engine is hot started; when it is determined that the engine is cold started and the current temperature of the front-stage SCR reaches a first start-injection temperature, the front-stage nozzle starts urea injection, and the first start-injection temperature is the temperature at which urea begins to hydrolyze; When it is determined that the engine is hot started and the current temperature of the front-stage SCR reaches a second injection start temperature, the front-stage nozzle starts urea injection.

8. A post-treatment SCR two-way urea injection system, characterized in that: include: A data acquisition module and a turbine, a front-stage SCR, a DOC, a DPF and a rear-stage SCR connected in sequence, a front-stage nozzle is arranged between the turbine and the front-stage SCR, and a rear-stage nozzle is arranged between the DPF and the rear-stage SCR; The data acquisition module includes a temperature sensor and a NOx sensor. The temperature sensor is used to collect the temperature of the engine, the front-stage SCR and the rear-stage SCR; the NOx sensor is used to collect the NOx content in the exhaust gas entering the front-stage SCR and the rear-stage SCR; It also includes the post-treatment SCR two-way urea injection control device as described in claim 7.

9. An engineering equipment, characterized in that: It comprises the post-treatment SCR two-way urea injection system as described in claim 8.

10. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the program, the post-treatment SCR two-way urea injection control method as claimed in any one of claims 1 to 6 is implemented.

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