Engine exhaust ammonia leakage detection method, device and engine control system

Abstract

The application provides an engine exhaust ammonia leakage detection method, device and engine control system. When the original exhaust NOx is in a stable state, the ammonia nitrogen ratio of urea injection is adjusted, and the measurement values of upstream and downstream NOx sensors are combined, so that the ammonia leakage in the exhaust can be accurately judged and recognized, and the false alarm condition of the SCR efficiency fault caused by the ammonia leakage in the exhaust can be avoided.

Description

Technical Field

[0001] This invention relates to the field of engine technology, and specifically to an engine ammonia leak detection method, device, equipment, and engine control system. Background Technology

[0002] To reduce air pollution from engine exhaust, it's necessary to reduce the composition of harmful gases in the exhaust. This requires ensuring the conversion efficiency of the Selective Catalytic Reduction (SCR) system is above 95%, while simultaneously ensuring that NH3 in the exhaust cycle does not exceed 10 ppm. Furthermore, during actual vehicle operation, urea is used to eliminate NOx emissions. To ensure NOx emissions remain within permissible limits, engine systems often experience urea over-injection, with the ammonia-to-nitrogen ratio typically exceeding 1.05 to 1.10. Severe urea over-injection can lead to excessive ammonia leakage, causing NH3 pollution.

[0003] Currently, diesel engine aftertreatment systems are equipped with upstream and downstream NOx sensors, which can monitor NOx emissions from upstream and downstream sources respectively. However, they cannot accurately distinguish between NOx and NH3. If the urea-ammonia nitrogen ratio is too high, resulting in excessive NH3 emissions in the exhaust gas and ammonia leakage, the downstream NOx sensor reading will be higher than the actual downstream NOx emissions, which can easily cause false alarms due to SCR efficiency failure. Summary of the Invention

[0004] In view of this, embodiments of the present invention provide a method, apparatus and engine control system for detecting ammonia leakage in engine exhaust gas, so as to identify whether there is ammonia leakage in the exhaust gas and thus prevent false alarms of SCR efficiency failure.

[0005] To achieve the above objectives, the embodiments of the present invention provide the following technical solutions:

[0006] A method for detecting ammonia leakage in engine exhaust gas includes:

[0007] Determine whether the NOx emissions from the engine are in a stable state;

[0008] When the original NOx emissions are in a stable state, adjust the ammonia-nitrogen ratio of the urea injection.

[0009] Based on the measurements from upstream and downstream NOx sensors during the adjustment of the ammonia-nitrogen ratio, it is determined whether there is ammonia leakage in the exhaust gas.

[0010] Optionally, the above-mentioned engine exhaust ammonia leakage detection method further includes, when the original NOx emissions are not in a stable state:

[0011] By adjusting the target combustion parameters of the engine, the NOx emissions from the engine are brought to a stable state.

[0012] Optionally, in the above-mentioned engine exhaust ammonia leakage detection method, adjusting the target combustion parameters of the engine to bring the original NOx emissions of the engine into a stable state includes:

[0013] The original NOx emissions are stabilized by adjusting the engine's injection timing, rail pressure, and EGR rate.

[0014] Optionally, in the above-mentioned engine exhaust ammonia leak detection method, determining whether there is ammonia leak in the exhaust gas based on the measured values ​​of upstream and downstream NOx sensors during the adjustment of the ammonia-nitrogen ratio includes:

[0015] The NOx conversion efficiency during the adjustment of the ammonia-nitrogen ratio is calculated based on the measurements from upstream and downstream NOx sensors.

[0016] Based on the change in NOx conversion efficiency, determine whether there is ammonia leakage in the exhaust gas.

[0017] Optionally, in the above-mentioned method for detecting ammonia leakage in engine exhaust, adjusting the ammonia-nitrogen ratio of urea injection includes: reducing the ammonia-nitrogen ratio of urea injection;

[0018] Based on the change in NOx conversion efficiency, determine whether there is ammonia leakage in the exhaust gas, including:

[0019] When the NOx conversion efficiency decreases monotonically during the adjustment of the ammonia-nitrogen ratio, it is determined that there is no ammonia leakage in the exhaust gas.

[0020] When the NOx conversion efficiency first increases and then decreases during the adjustment of the ammonia-nitrogen ratio, it is determined that there is ammonia leakage in the exhaust gas.

[0021] Optionally, in the above-mentioned method for detecting ammonia leakage in engine exhaust, adjusting the ammonia-nitrogen ratio of urea injection includes: increasing the ammonia-nitrogen ratio of urea injection;

[0022] Based on the change in NOx conversion efficiency, determine whether there is ammonia leakage in the exhaust gas, including:

[0023] When the NOx conversion efficiency increases monotonically during the adjustment of the ammonia-nitrogen ratio, it is determined that there is no ammonia leakage in the exhaust gas.

[0024] When the NOx conversion efficiency decreases monotonically during the adjustment of the ammonia-nitrogen ratio, it is determined that there is ammonia leakage in the exhaust gas.

[0025] Optionally, in the above-mentioned engine exhaust ammonia leak detection method, determining whether there is ammonia leak in the exhaust gas based on the measured values ​​of upstream and downstream NOx sensors during the adjustment of the ammonia-nitrogen ratio includes:

[0026] Based on the changes in the downstream NOx sensor readings during the adjustment of the ammonia-nitrogen ratio, it can be determined whether there is ammonia leakage in the exhaust gas.

[0027] Optionally, the above-mentioned engine exhaust ammonia leak detection method, before determining whether the engine's original NOx emissions are in a stable state, further includes:

[0028] Determine whether the engine's operating status and after-processing status are in a stable state. If the engine's operating status and after-processing status are in a stable state, continue to execute the subsequent process.

[0029] An engine exhaust ammonia leak detection device, comprising:

[0030] The exhaust status determination unit is used to determine whether the NOx in the engine's exhaust is in a stable state.

[0031] The ammonia-nitrogen ratio control unit adjusts the ammonia-nitrogen ratio of urea injection when the original NOx emissions are in a stable state.

[0032] The leakage detection unit is used to determine whether there is ammonia leakage in the exhaust gas based on the measurement values ​​of upstream and downstream NOx sensors during the adjustment of the ammonia-nitrogen ratio.

[0033] An engine control system includes a memory and a processor;

[0034] The memory is used to store programs;

[0035] The processor is used to execute the program to implement each step of the engine exhaust ammonia leakage detection method described in any of the above claims.

[0036] Based on the above technical solution, in the above solution provided by the embodiments of the present invention, when the original NOx is in a stable state, by adjusting the urea injection ammonia nitrogen ratio and combining the measurement values ​​of upstream and downstream NOx sensors, it is possible to accurately determine and identify ammonia leakage in the exhaust gas, thereby avoiding false alarms of SCR efficiency failure caused by ammonia leakage in the exhaust gas. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0038] Figure 1 This is a schematic flowchart of the engine exhaust ammonia leakage detection method disclosed in the embodiments of this application;

[0039] Figure 2 This is a schematic diagram of the ammonia leak monitoring condition identification method disclosed in the embodiments of this application;

[0040] Figure 3 This is a flowchart illustrating an engine exhaust ammonia leak detection method disclosed in another embodiment of this application;

[0041] Figure 4 This is a flowchart illustrating an engine exhaust ammonia leak detection method disclosed in another embodiment of this application;

[0042] Figure 5 This is a flowchart illustrating an engine exhaust ammonia leak detection method disclosed in another embodiment of this application;

[0043] Figure 6 This is a flowchart illustrating an engine exhaust ammonia leakage detection method disclosed in another embodiment of this application;

[0044] Figure 7 This is a schematic diagram of the structure of the engine exhaust ammonia leak detection device disclosed in the embodiments of this application;

[0045] Figure 8 This is a schematic diagram of the engine control system disclosed in an embodiment of this application. Detailed Implementation

[0046] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0047] This solution adjusts the ammonia-nitrogen ratio of urea injection when the NOx in the engine's original exhaust is stable. By judging the measurement values ​​of upstream and downstream NOx sensors after adjusting the ammonia-nitrogen ratio, it can accurately identify whether there is ammonia leakage in the engine exhaust.

[0048] For details, see Figure 1 The engine exhaust ammonia leakage detection method disclosed in this application includes:

[0049] Step S101: Determine whether the NOx emissions from the engine are in a stable state.

[0050] In this solution, the stability of the original NOx emissions can be determined based on the fluctuation amplitude of the actual NOx value corresponding to the current original emissions of the engine. The actual NOx value can be directly retrieved from the ECU (Electronic Control Unit). After obtaining the actual NOx value corresponding to the current original emissions of the engine, it is determined whether its fluctuation range is greater than a preset fluctuation range. The preset fluctuation range can be set by the user according to their needs. If the original NOx emissions fluctuation is within ±0.5, the original NOx emissions can be considered to be in a stable state.

[0051] Step S102: When the original NOx emissions are in a stable state, adjust the ammonia-nitrogen ratio of the urea injection.

[0052] Under different ammonia-to-nitrogen ratios, and with and without ammonia leakage, the measured values ​​of upstream and downstream NOx sensors differ. Therefore, in this step, when the original exhaust NOx is detected to be in a stable state, the ammonia-to-nitrogen ratio of urea injection can be controlled to determine whether there is ammonia leakage in the exhaust gas, while ensuring relatively stable engine operating conditions. Whether to control the ammonia-to-nitrogen ratio to increase or decrease can be determined according to design requirements.

[0053] Step S103: Based on the measurement values ​​of upstream and downstream NOx sensors during the adjustment of the ammonia-nitrogen ratio, determine whether there is ammonia leakage in the exhaust gas.

[0054] During the process of controlling the change of the ammonia-nitrogen ratio, the measurement values ​​of the upstream and downstream NOx sensors are acquired in real time. Further analysis of the measurement values ​​of the upstream and downstream NOx sensors can determine whether there is ammonia leakage in the exhaust gas.

[0055] The technical solution disclosed in the above embodiments of this application can accurately identify ammonia leakage in the exhaust gas by adjusting the urea injection ammonia-nitrogen ratio when the original NOx emissions are in a stable state, combined with the measurement values ​​of upstream and downstream NOx sensors during the process, thus avoiding false alarms of SCR efficiency failure caused by ammonia leakage in the exhaust gas.

[0056] In the technical solution disclosed in this embodiment, the NOx emissions from the engine can be adjusted by regulating the target combustion parameters. When the NOx emissions are not stable, the target combustion parameters can be adjusted to bring the NOx emissions into a stable state. Specifically, the target combustion parameters can be the injection timing, rail pressure, and EGR rate. By adjusting the injection timing, rail pressure, and EGR rate, the NOx emissions from the engine can be brought into and maintained in a stable state, thus preventing misjudgments of ammonia leakage caused by fluctuations in NOx emissions.

[0057] In the technical solution disclosed in this embodiment, in order to further eliminate factors affecting SCR conversion efficiency and improve the accuracy of ammonia leakage judgment, the technical solution disclosed in this embodiment requires that the engine operating state and aftertreatment state be relatively stable before determining whether the engine's primary exhaust NOx is in a stable state. Only when the engine operating state and aftertreatment state are in a stable state can the subsequent ammonia leakage judgment process continue. If the engine operating state and aftertreatment state are not in a stable state, it is necessary to continue waiting until the engine operating state and aftertreatment state reach a stable state. Specifically, see... Figure 2 The engine's operating status can be identified by monitoring engine operating mode, urea injection status, NOx sensor operating status, speed changes, torque changes, SCR temperature changes, and exhaust flow rate changes. Once the above conditions for ammonia leak monitoring are met, the engine operating status and aftertreatment status are considered relatively stable, eliminating factors affecting SCR conversion efficiency. Specifically, the ammonia leak monitoring conditions can refer to: stable engine operating mode, normal urea injection status with no related fault errors, normal NOx sensor operation with no related fault errors, speed and torque within a certain range, SCR temperature variation within a certain time period not exceeding a certain value, and exhaust flow rate variation not exceeding a certain value. The specific values ​​of "certain range" and "certain value" can be configured according to their corresponding parameter types.

[0058] In this embodiment, when determining whether there is ammonia leakage in the exhaust gas based on the measured values ​​of upstream and downstream NOx sensors during the adjustment of the ammonia-nitrogen ratio, the determination can be made by observing the change in NOx conversion efficiency during the adjustment of the ammonia-nitrogen ratio, or by directly determining the change in the measured values ​​of downstream NOx sensors during the adjustment of the ammonia-nitrogen ratio.

[0059] The adjustment of the ammonia-nitrogen ratio of urea injection can include decreasing the ammonia-nitrogen ratio of urea injection and increasing the ammonia-nitrogen ratio of urea injection. Whether to decrease or increase the ammonia-nitrogen ratio of urea injection can be selected according to design requirements.

[0060] When the adjustment of the ammonia-nitrogen ratio of urea injection is to reduce the ammonia-nitrogen ratio of urea injection, see [reference needed]. Figure 3 The method of determining whether there is ammonia leakage in the exhaust gas based on the change in NOx conversion efficiency includes:

[0061] Step S301: During the process of adjusting the ammonia-nitrogen ratio, calculate the NOx conversion efficiency.

[0062] In this step, during the adjustment of the ammonia-nitrogen ratio, the NOx conversion efficiency during the adjustment process is calculated based on the measurements from upstream and downstream NOx sensors.

[0063] Step S302: Calculate the change curve of NOx conversion efficiency during the process of adjusting the ammonia-nitrogen ratio.

[0064] In this step, based on the measurements of upstream and downstream NOx sensors during the adjustment of the ammonia-nitrogen ratio, the NOx conversion efficiency after adjusting the ammonia-nitrogen ratio at each time point is calculated, and a curve showing the change of the NOx conversion efficiency during the adjustment of the ammonia-nitrogen ratio is generated.

[0065] Step S303: Determine whether the change curve is monotonically decreasing or first increasing and then decreasing;

[0066] This step analyzes the trend of NOx conversion efficiency based on the curve. When the curve shows a monotonically decreasing NOx conversion efficiency, it is determined that there is no ammonia leakage in the exhaust gas. Conversely, when the NOx conversion efficiency first increases and then decreases, it is determined that there is ammonia leakage in the exhaust gas. In this case, if an ammonia leakage is determined, the analysis results can be displayed to the user to facilitate timely troubleshooting of the engine malfunction.

[0067] When the adjustment of the ammonia-nitrogen ratio of urea injection is to increase the ammonia-nitrogen ratio of urea injection, see [reference needed]. Figure 4 The method of determining whether there is ammonia leakage in the exhaust gas based on the change in NOx conversion efficiency includes:

[0068] Step S401: During the process of adjusting the ammonia-nitrogen ratio, calculate the NOx conversion efficiency.

[0069] In this step, during the adjustment of the ammonia-nitrogen ratio, the NOx conversion efficiency during the adjustment process is calculated based on the measurements from upstream and downstream NOx sensors.

[0070] Step S402: Calculate the change curve of NOx conversion efficiency during the process of adjusting the ammonia-nitrogen ratio.

[0071] In this step, based on the measurements of upstream and downstream NOx sensors during the adjustment of the ammonia-nitrogen ratio, the NOx conversion efficiency after adjusting the ammonia-nitrogen ratio at each time point is calculated, and a curve showing the change of the NOx conversion efficiency during the adjustment of the ammonia-nitrogen ratio is generated.

[0072] Step S403: Determine whether the change curve is monotonically increasing or monotonically decreasing.

[0073] In this step, the NOx conversion efficiency is used to determine whether there is an ammonia leak in the exhaust gas. If the NOx conversion efficiency increases monotonically during the adjustment of the ammonia-nitrogen ratio, it is determined that there is no ammonia leak. Conversely, if the NOx conversion efficiency decreases monotonically during the adjustment of the ammonia-nitrogen ratio, it is determined that there is an ammonia leak in the exhaust gas. When an ammonia leak is detected in the exhaust gas, the analysis results can be displayed to the user to facilitate timely troubleshooting of the engine malfunction.

[0074] When the adjustment of the ammonia-nitrogen ratio of urea injection is to reduce the ammonia-nitrogen ratio of urea injection, see [reference needed]. Figure 5 The method of determining whether there is ammonia leakage in the exhaust gas based on changes in downstream NOx sensor measurements includes:

[0075] Step S501: During the process of calculating and adjusting the ammonia-nitrogen ratio, the measurement value of the downstream NOx sensor is obtained.

[0076] Step S502: Calculate the change curve of the downstream NOx sensor measurement value during the process of adjusting the ammonia nitrogen ratio.

[0077] In this step, a curve showing the change in the measured value of the downstream NOx sensor is constructed based on the measured value of the downstream NOx sensor during the adjustment of the ammonia-nitrogen ratio.

[0078] Step S503: Determine whether the change curve is monotonically increasing or decreasing first and then increasing;

[0079] This step analyzes the trend of the downstream NOx sensor's measured values ​​based on the curve. When the downstream NOx sensor's measured value shows a monotonically increasing trend, it is determined that there is no ammonia leak in the exhaust gas. When the downstream NOx sensor's measured value first decreases and then increases, it is determined that there is an ammonia leak in the exhaust gas. In this case, if an ammonia leak is determined to be present in the exhaust gas, the analysis results can be displayed to the user so that the user can promptly address the engine malfunction.

[0080] When the adjustment of the ammonia-nitrogen ratio of urea injection is to increase the ammonia-nitrogen ratio of urea injection, see [reference needed]. Figure 6 The method of determining whether there is ammonia leakage in the exhaust gas based on changes in downstream NOx sensor measurements includes:

[0081] Step S601: During the process of calculating and adjusting the ammonia-nitrogen ratio, the measurement value of the downstream NOx sensor is obtained.

[0082] Step 6502: Calculate the change curve of the downstream NOx sensor measurement value during the process of adjusting the ammonia nitrogen ratio.

[0083] In this step, a curve showing the change in the measured value of the downstream NOx sensor is generated based on the measured value of the downstream NOx sensor during the adjustment of the ammonia-nitrogen ratio.

[0084] Step S603: Determine whether the change curve is monotonically decreasing or monotonically increasing;

[0085] This step analyzes the trend of the downstream NOx sensor's measured values ​​based on the curve. When the downstream NOx sensor's measured value shows a monotonically decreasing trend, it is determined that there is no ammonia leak in the exhaust gas; conversely, when the downstream NOx sensor's measured value shows a monotonically increasing trend, it is determined that there is an ammonia leak in the exhaust gas. In this case, if an ammonia leak is determined to be present in the exhaust gas, the analysis results can be displayed to the user to facilitate timely troubleshooting of the engine malfunction.

[0086] In the technical solution disclosed in this embodiment, after the determination of whether there is ammonia leakage in the exhaust gas is completed, the engine combustion parameter control and urea injection ammonia nitrogen ratio control can be exited, so that the engine combustion parameter control and urea injection ammonia nitrogen ratio can be restored to the previous control state, and the relevant parameters can be restored to their original state and continue to operate.

[0087] As can be seen from the above scheme, this patent identifies the engine's operating conditions. Under normal urea injection and with upstream and downstream NOx sensors functioning normally, it determines that the engine is operating under relatively stable conditions by measuring aftertreatment temperature and exhaust flow, and then initiates the ammonia leak monitoring function. After the ammonia leak monitoring function is activated, it controls relevant engine combustion parameters to ensure relatively stable NOx levels in the exhaust. Once the engine operating conditions and exhaust are relatively stable, it controls the ammonia-to-nitrogen ratio of the urea injection and calculates the NOx conversion efficiency based on the measurements from the upstream and downstream NOx sensors. Based on the changes in NOx conversion efficiency or the downstream NOx sensor measurement, it determines whether there is an ammonia leak in the exhaust gas. Specifically, when the ammonia-to-nitrogen ratio is reduced, if the conversion efficiency decreases directly or the downstream NOx sensor measurement increases directly, it is determined that there is no ammonia leak in the exhaust gas; if the conversion efficiency increases first and then decreases, or the downstream NOx sensor measurement decreases first and then increases, it is determined that there is an ammonia leak in the exhaust gas. If the conversion efficiency increases directly or the downstream NOx sensor reading decreases directly when the ammonia-nitrogen ratio increases, it indicates that there is no ammonia leakage in the exhaust gas; if the conversion efficiency decreases directly and monotonically or the downstream NOx sensor reading increases directly, it indicates that there is ammonia leakage in the exhaust gas.

[0088] This embodiment discloses an engine exhaust ammonia leak detection device. For the specific working content of each unit in the device, please refer to the above method embodiment.

[0089] The engine exhaust ammonia leak detection device provided in the embodiments of the present invention is described below. The engine exhaust ammonia leak detection device described below and the engine exhaust ammonia leak detection method described above can be referred to and corresponded to each other.

[0090] See Figure 7 The engine exhaust ammonia leak detection device may include:

[0091] Original discharge status judgment unit 10, ammonia nitrogen ratio control unit 20 and leakage judgment unit 30;

[0092] The original exhaust state judgment unit 10 corresponds to step S101 in the above method and is used to determine whether the original exhaust NOx of the engine is in a stable state.

[0093] The ammonia-nitrogen ratio control unit 20 corresponds to step S102 in the above method. When the original NOx emission is in a stable state, the ammonia-nitrogen ratio of the urea injection is adjusted.

[0094] The leakage detection unit 30 corresponds to step S103 in the above method and is used to determine whether there is ammonia leakage in the exhaust gas based on the measurement values ​​of upstream and downstream NOx sensors during the process of adjusting the ammonia-nitrogen ratio.

[0095] The specific functions and execution strategies of the original discharge status judgment unit 10, ammonia nitrogen ratio control unit 20 and leakage judgment unit 30 can be found in the above method embodiments, and will not be repeated here.

[0096] In addition, this application also discloses an engine control system, see [link to relevant documentation]. Figure 8 The system may include at least one processor 100, at least one communication interface 200, at least one memory 300 and at least one communication bus 400, wherein the memory 300 is used to store a program; and the processor 100 is used to execute the program.

[0097] In this embodiment of the invention, the number of processor 100, communication interface 200, memory 300, and communication bus 400 is at least one, and the processor 100, communication interface 200, and memory 300 communicate with each other through communication bus 400; obviously, Figure 8 The communication connections shown for the processor 100, communication interface 200, memory 300, and communication bus 400 are optional.

[0098] Optionally, the communication interface 200 can be an interface of a communication module, such as the interface of a GSM module;

[0099] Processor 100 may be a central processing unit (CPU), an application-specific integrated circuit (ASIC), or one or more integrated circuits configured to implement embodiments of the present invention.

[0100] The memory 300 may include high-speed RAM memory, and may also include non-volatile memory, such as at least one disk storage device.

[0101] Specifically, the processor 100 executes the program to implement each step of the engine exhaust ammonia leakage detection method embodiment as described in any of the above embodiments.

[0102] For example, the processor 100 is used for:

[0103] Determine whether the NOx emissions from the engine are in a stable state;

[0104] When the original NOx emissions are in a stable state, adjust the ammonia-nitrogen ratio of the urea injection.

[0105] Based on the measurements from upstream and downstream NOx sensors during the adjustment of the ammonia-nitrogen ratio, it is determined whether there is ammonia leakage in the exhaust gas.

[0106] The processor 100 is also used to execute the various steps of the other engine exhaust ammonia leak detection method embodiments described above, which will not be repeated here.

[0107] Furthermore, this application also discloses an automobile that can be equipped with the aforementioned engine control system, and the automobile can be a gasoline vehicle, a natural gas vehicle, or a hybrid vehicle.

[0108] For ease of description, the above system is described by dividing it into various modules based on their functions. Of course, in implementing this application, the functions of each module can be implemented in one or more software and / or hardware.

[0109] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, for system or system embodiments, since they are basically similar to method embodiments, the description is relatively simple, and relevant parts can be referred to the descriptions in the method embodiments. The systems and system embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without creative effort.

[0110] Those skilled in the art will further recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0111] The steps of the methods or algorithms described in conjunction with the embodiments disclosed herein can be implemented directly by hardware, a software module executed by a processor, or a combination of both. The software module can be located in random access memory (RAM), main memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, removable disk, CD-ROM, or any other form of storage medium known in the art.

[0112] It should also be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0113] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for detecting ammonia leakage in engine exhaust gas, characterized in that, include: Determine whether the NOx emissions from the engine are in a stable state; When the original NOx emissions are in a stable state, the ammonia-nitrogen ratio of the urea injection is adjusted, including: decreasing the ammonia-nitrogen ratio of the urea injection and increasing the ammonia-nitrogen ratio of the urea injection. Based on the measurements of upstream and downstream NOx sensors during the adjustment of the ammonia-nitrogen ratio, it is determined whether there is ammonia leakage in the exhaust gas; including: calculating the NOx conversion efficiency during the adjustment of the ammonia-nitrogen ratio based on the measurements of upstream and downstream NOx sensors; determining whether there is ammonia leakage in the exhaust gas based on the change pattern of the NOx conversion efficiency; and determining whether there is ammonia leakage in the exhaust gas based on the change pattern of the downstream NOx sensor measurements during the adjustment of the ammonia-nitrogen ratio. Specifically, when the ammonia-nitrogen ratio is reduced, if the NOx conversion efficiency decreases monotonically or the downstream NOx sensor reading increases monotonically, it is determined that there is no ammonia leakage in the exhaust gas; if the NOx conversion efficiency increases first and then decreases or the downstream NOx sensor reading decreases first and then increases, it is determined that there is ammonia leakage in the exhaust gas. When the ammonia-nitrogen ratio is controlled to increase, if the NOx conversion efficiency increases monotonically or the downstream NOx sensor measurement decreases monotonically, it is determined that there is no ammonia leakage in the exhaust gas; if the NOx conversion efficiency decreases monotonically or the downstream NOx sensor measurement increases monotonically, it is determined that there is ammonia leakage in the exhaust gas.

2. The method for detecting ammonia leakage in engine exhaust gas according to claim 1, characterized in that, When the original NOx emissions are not in a stable state, the following is also included: By adjusting the target combustion parameters of the engine, the NOx emissions from the engine are brought to a stable state.

3. The method for detecting ammonia leakage in engine exhaust gas according to claim 1, characterized in that, By adjusting the target combustion parameters of the engine, the NOx emissions of the engine are brought to a stable state, including: The original NOx emissions are stabilized by adjusting the engine's injection timing, rail pressure, and EGR rate.

4. The method for detecting ammonia leakage in engine exhaust gas according to claim 1, characterized in that, Before determining whether the engine's NOx emissions are in a stable state, the following steps are also taken: Determine whether the engine's operating status and after-processing status are in a stable state. If the engine's operating status and after-processing status are in a stable state, continue to execute the subsequent process.

5. An engine exhaust ammonia leak detection device, characterized in that, include: The exhaust status determination unit is used to determine whether the NOx in the engine's exhaust is in a stable state. The ammonia nitrogen ratio control unit adjusts the ammonia nitrogen ratio of urea injection when the original NOx emission is in a stable state, including: decreasing the ammonia nitrogen ratio of urea injection and increasing the ammonia nitrogen ratio of urea injection; The leakage detection unit is used to determine whether there is ammonia leakage in the exhaust gas based on the measurement values ​​of upstream and downstream NOx sensors during the adjustment of the ammonia-nitrogen ratio. The leakage detection unit is specifically used for: calculating the NOx conversion efficiency during the adjustment of the ammonia-nitrogen ratio based on the measured values ​​of the upstream and downstream NOx sensors; determining whether there is ammonia leakage in the exhaust gas based on the change pattern of the NOx conversion efficiency; and determining whether there is ammonia leakage in the exhaust gas based on the change pattern of the measured values ​​of the downstream NOx sensor during the adjustment of the ammonia-nitrogen ratio. Specifically, when the ammonia-nitrogen ratio is reduced, if the NOx conversion efficiency decreases monotonically or the downstream NOx sensor reading increases monotonically, it is determined that there is no ammonia leakage in the exhaust gas; if the NOx conversion efficiency increases first and then decreases or the downstream NOx sensor reading decreases first and then increases, it is determined that there is ammonia leakage in the exhaust gas. When the ammonia-nitrogen ratio is controlled to increase, if the NOx conversion efficiency increases monotonically or the downstream NOx sensor measurement decreases monotonically, it is determined that there is no ammonia leakage in the exhaust gas; if the NOx conversion efficiency decreases monotonically or the downstream NOx sensor measurement increases monotonically, it is determined that there is ammonia leakage in the exhaust gas.

6. An engine control system, characterized in that, Including memory and processor; The memory is used to store programs; The processor is used to execute the program to implement each step of the engine exhaust ammonia leak detection method as described in any one of claims 1-4.

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