Engine raw exhaust drift identification and processing method and device

Abstract

The application provides an engine raw emission drift identification and processing method and device. When a whole vehicle is driven in non-road operation, the SCR conversion efficiency is calculated according to the calibrated upstream NOx flow and the first downstream NOx flow of the whole vehicle. If the SCR conversion efficiency is less than the preset SCR conversion efficiency, the raw emission drift detection is not performed in the driving cycle of the whole vehicle, and the engine meets the raw emission drift detection condition, the raw emission drift detection strategy is executed to determine the raw emission drift coefficient. If it is determined that the engine has the raw emission drift according to the raw emission drift coefficient, the calibrated upstream NOx flow is corrected by using the raw emission drift coefficient. The target SCR conversion efficiency is calculated according to the second downstream NOx flow of the whole vehicle and the corrected calibrated upstream NOx flow. If the target SCR conversion efficiency is not less than the preset SCR conversion efficiency, it is determined that the engine does not have the SCR removal fault, and a message representing the SCR removal fault is not output.

Description

Technical Field

[0001] This invention relates to the field of engine technology, and more specifically, to a method and apparatus for identifying and processing engine exhaust drift. Background Technology

[0002] Currently, off-road engine exhaust aftertreatment systems typically only install a downstream NOx sensor for Selective Catalytic Reduction (SCR), omitting an upstream NOx sensor. The upstream NOx level is obtained through original engine calibration. Furthermore, when using diesel engines off-road, SCR removal faults are used to indicate whether the aftertreatment SCR conversion rate is normal; therefore, consistency between the original and after-treatment engine exhaust is crucial.

[0003] However, due to the influence of various factors on the engine's condition (such as ambient humidity and intercooler temperature), the engine combustion deviates from the ideal state. This causes a shift in the upstream NOx flow rate from the theoretical upstream NOx flow rate. In other words, under the same speed and torque conditions, the actual upstream NOx flow rate of the vehicle deviates from the theoretical upstream NOx flow rate calibrated by the original engine. Since the urea injection quantity is calculated based on the upstream NOx flow rate, if the upstream NOx flow rate deviates significantly, continuing to calculate the urea injection quantity based on the theoretical upstream NOx flow rate may result in insufficient actual urea injection. This could lead to unreacted upstream NOx entering the SCR downstream. Furthermore, because the actual upstream NOx flow rate has shifted, when calculating the SCR conversion efficiency, the downstream NOx flow rate is greater than the upstream NOx flow rate (the original exhaust NOx flow rate under theoretical conditions), causing the SCR conversion efficiency to be lower than 0, resulting in a false SCR removal fault alarm. Summary of the Invention

[0004] In view of this, the present invention provides a method and apparatus for identifying and processing engine exhaust drift, with the aim of ensuring the accuracy of SCR removal fault reporting.

[0005] The first aspect of this invention provides a method for identifying and processing engine exhaust drift, the method comprising:

[0006] When the vehicle is in operation off-road, the first downstream NOx flow of the vehicle is obtained, and the SCR conversion efficiency is calculated based on the calibrated upstream NOx flow and the first downstream NOx flow.

[0007] If the SCR conversion efficiency is less than the preset SCR conversion efficiency, and no original exhaust drift detection has been performed in the driving cycle of the whole vehicle, determine whether the engine of the whole vehicle meets the original exhaust drift detection conditions.

[0008] If the engine meets the original exhaust drift detection conditions, execute the original exhaust drift detection strategy to determine the original exhaust drift coefficient;

[0009] If it is determined that the engine has experienced original exhaust drift based on the original exhaust drift coefficient, the original exhaust drift coefficient is used to correct the calibrated upstream NOx flow rate;

[0010] Obtain the second downstream NOx flow rate of the entire vehicle, and calculate the target SCR conversion efficiency based on the second downstream NOx flow rate and the corrected calibrated upstream NOx flow rate;

[0011] If the target SCR conversion efficiency is not less than the preset SCR conversion efficiency, it is determined that the engine has not experienced an SCR removal fault, and no message indicating an SCR removal fault is output.

[0012] Optionally, the method further includes:

[0013] If a drive cycle of the vehicle has been performed to detect original exhaust drift, or if the original exhaust drift coefficient indicates that the engine has not experienced original exhaust drift, or if the target SCR conversion efficiency is less than the preset SCR conversion efficiency, a message indicating an SCR removal fault is output.

[0014] Optionally, the method further includes:

[0015] If the SCR conversion efficiency is less than the preset SCR conversion efficiency, the original exhaust drift detection status of the whole vehicle is obtained;

[0016] Determine whether the original row drift detection state is 0;

[0017] If the original drift detection status is 0, it is determined that no original drift detection has been performed in the driving cycle of the vehicle.

[0018] If the original drift detection status is not 0, it is determined that the original drift detection has been performed in the driving cycle of the vehicle.

[0019] Optionally, the method further includes:

[0020] If the engine does not meet the original drift detection conditions, obtain the current time of the engine;

[0021] When the current time of the engine differs from the current time of the engine by a preset time interval, the engine is re-evaluated to determine whether it meets the original drift detection conditions.

[0022] If the engine still does not meet the original drift detection conditions, no message indicating SCR removal failure will be output.

[0023] If the engine meets the original exhaust drift detection conditions, the original exhaust drift detection strategy is executed to determine the original exhaust drift coefficient.

[0024] Optionally, if the SCR conversion efficiency is less than the preset SCR conversion efficiency, and no original exhaust drift detection has been performed during the vehicle's driving cycle, determining whether the vehicle's engine meets the original exhaust drift detection conditions includes:

[0025] If the SCR conversion efficiency is less than the preset SCR conversion efficiency, and no original drift detection has been performed in the driving cycle of the whole vehicle, obtain the whole vehicle information.

[0026] Determine whether the vehicle information indicates that the NOx sensor is effective and whether it indicates that the engine's operating mode is the target operating mode;

[0027] If the vehicle information indicates that the NOx sensor is effective and indicates that the engine is operating in the target mode, then the engine is determined to meet the original emission drift detection conditions.

[0028] If the vehicle information indicates that the NOx sensor is invalid, and / or indicates that the engine's operating mode is not the target operating mode, it is determined that the engine does not meet the original emission drift detection conditions.

[0029] Optionally, if the engine meets the original exhaust drift detection conditions, an original exhaust drift detection strategy is executed to determine the original exhaust drift coefficient, including:

[0030] If the engine meets the original drift detection conditions, stop injecting urea and accumulate the time when urea injection is stopped;

[0031] Obtain the SCR exhaust temperature, and determine the ammonia storage emptying rate based on the SCR exhaust temperature and the calibrated upstream NOx flow rate;

[0032] Empty the ammonia storage in the SCR based on the ammonia storage emptying rate, and record the target time required to empty the ammonia storage in the SCR;

[0033] When the cumulative time for urea injection reaches the first preset time limit and the target time is greater than the second preset time limit, the ammonia storage is determined to be emptied.

[0034] Once the ammonia storage is emptied, stop urea injection and obtain the third downstream NOx flow rate of the entire vehicle;

[0035] The original discharge drift coefficient is determined based on the upstream NOx flow rate and the third downstream NOx flow rate.

[0036] Optionally, determining the original discharge drift coefficient based on the calibrated upstream NOx flow rate and the third downstream NOx flow rate includes:

[0037] Based on a preset operating condition range, the calibrated upstream NOx flow and the third downstream NOx flow are integrated using a preset integration window;

[0038] When it is detected that the quality obtained by integrating the calibrated upstream NOx flow rate in the preset integration window reaches the preset quality, it is determined that the preset integration window is completed;

[0039] When the preset integration window is completed, the upstream NOx mass corresponding to the calibrated upstream NOx flow rate and the downstream NOx mass corresponding to the third downstream NOx flow rate are obtained.

[0040] The original emission drift coefficient is calculated based on the upstream NOx mass and the downstream NOx mass.

[0041] Optionally, the method further includes:

[0042] Determine whether the original row drift coefficient is greater than the preset original row drift coefficient;

[0043] If the original displacement drift coefficient is greater than the preset original displacement drift coefficient, it is determined that the engine has experienced original displacement drift;

[0044] If the original drift coefficient is not greater than the preset original drift coefficient, it is determined that the engine has experienced non-original drift.

[0045] A second aspect of the present invention provides an engine exhaust drift identification and processing device, the device comprising:

[0046] The SCR conversion efficiency calculation unit is used to obtain the first downstream NOx flow of the vehicle when the vehicle is in operation off-road, and to calculate the SCR conversion efficiency based on the calibrated upstream NOx flow and the first downstream NOx flow.

[0047] The first judgment unit is used to determine whether the engine of the vehicle meets the original drift detection conditions if the SCR conversion efficiency is less than the preset SCR conversion efficiency and no original drift detection has been performed in the driving cycle of the vehicle.

[0048] The execution unit is used to execute the original exhaust drift detection strategy and determine the original exhaust drift coefficient if the engine meets the original exhaust drift detection conditions;

[0049] The correction unit is used to correct the calibrated upstream NOx flow rate by using the original exhaust drift coefficient if it is determined that the engine has experienced original exhaust drift based on the original exhaust drift coefficient.

[0050] The target SCR conversion efficiency calculation unit is used to obtain the second downstream NOx flow of the whole vehicle, and calculate the target SCR conversion efficiency based on the second downstream NOx flow and the corrected calibrated upstream NOx flow.

[0051] The first non-output unit is used to determine that the engine has not experienced an SCR removal fault if the target SCR conversion efficiency is not less than the preset SCR conversion efficiency, and not to output a message indicating an SCR removal fault.

[0052] Optionally, the device further includes:

[0053] The output unit is configured to output a message indicating an SCR removal fault if: a drive cycle of the vehicle has been performed for original exhaust drift diagnosis; or, the original exhaust drift coefficient determines that the engine has not experienced original exhaust drift; or, the target SCR conversion efficiency is less than a preset SCR conversion efficiency.

[0054] This invention provides a method and apparatus for identifying and processing engine exhaust drift. When detecting engine drift during off-road operation, the system first determines whether the current SCR conversion efficiency is low. If the current SCR conversion efficiency is low, to avoid false SCR removal fault reports, it first determines whether exhaust drift detection has been performed during the vehicle driving cycle. If exhaust drift detection has not been performed during the vehicle driving cycle, and the engine meets the exhaust drift detection requirements, an exhaust drift detection strategy can be executed to determine the exhaust drift coefficient. If exhaust drift is determined based on the exhaust drift coefficient, it indicates that the engine's calibrated upstream NOx flow has shifted. The exhaust drift coefficient can be used to correct the calibrated upstream NOx flow, and the corrected calibrated upstream NOx flow and downstream NOx flow (third downstream NOx flow) can be used to recalculate the SCR conversion efficiency (target SCR conversion efficiency). The recalculated SCR conversion efficiency can then be used to determine whether an SCR removal fault has occurred, making SCR removal fault diagnosis more accurate and ensuring the accuracy of SCR removal fault reports. Attached Figure Description

[0055] 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.

[0056] Figure 1 This is a schematic diagram of a process for identifying and processing engine exhaust drift, provided by an embodiment of the present invention.

[0057] Figure 2 An example diagram illustrating an engine exhaust drift identification and processing method provided in an embodiment of the present invention;

[0058] Figure 3 This is a schematic diagram of the structure of an engine exhaust drift identification and processing device provided in an embodiment of the present invention. Detailed Implementation

[0059] 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.

[0060] The term "comprising" and its variations as used herein are open-ended inclusions, meaning "including but not limited to". The term "based on" means "at least partially based on". The term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments". Definitions of other terms will be given in the description below.

[0061] It should be noted that the concepts of "first" and "second" mentioned in this invention are only used to distinguish different devices, modules or units, and are not used to limit the order of functions performed by these devices, modules or units or their interdependencies.

[0062] It should be noted that the terms "a" and "a plurality of" used in this invention disclosure are illustrative rather than restrictive. Those skilled in the art should understand that, unless otherwise expressly indicated in the context, they should be understood as "one or more".

[0063] It should be noted that in the technical solution disclosed herein, the acquisition, collection, storage, use, processing, transmission, provision, disclosure, and application of data all comply with the provisions of relevant laws and regulations, necessary confidentiality measures have been taken, and they do not violate public order and good morals.

[0064] To better understand this invention, the technical terms used in this invention are explained below:

[0065] SCR removal fault: A non-road warning fault used to identify whether engine emissions exceed regulatory limits.

[0066] SCR conversion efficiency: downstream NOx flow / upstream NOx flow.

[0067] Engine consistency: The combustion of an engine is affected by various external factors, and consistency means whether the combustion of different engines is consistent.

[0068] See Figure 1 This diagram illustrates a flow chart of an engine exhaust drift identification and processing method provided by an embodiment of the present invention. Applicable to the engines of a complete vehicle, the method specifically includes the following steps:

[0069] S101: When the vehicle is used for off-road operations, the SCR conversion efficiency is calculated based on the vehicle's calibrated upstream NOx flow rate and the first downstream NOx flow rate.

[0070] In this embodiment of the invention, the applicant has discovered that when the SCR conversion efficiency of the whole vehicle is too low, an SCR removal fault will be reported. Therefore, when it is detected that the whole vehicle is driving off the road, the current SCR conversion efficiency of the whole vehicle can be determined first, so that it can be determined whether an SCR removal fault needs to be reported based on the SCR conversion efficiency.

[0071] It should be noted that non-roads can include: self-built and self-managed urban alleys or village roads not included in the planning, or roads that are self-built and self-managed; rural farm roads such as cement roads, asphalt roads, and gravel roads used for field cultivation; road sections built in front of or behind villagers' houses or roads formed by natural traffic flow; roads between buildings in closed residential communities; internal roads of government agencies, organizations, and units; dedicated roads in factories, mines, enterprises, railway stations, airports, ports, and freight yards; road sections that have not yet been transferred to the public security traffic department after the relocation of villages to residential communities; yards for drying crops; road sections that are under construction and not yet completed or have been completed but not transferred to the public security traffic department; and other road sections not included in the scope of public transportation management, etc. This embodiment of the invention does not limit these categories.

[0072] During the specific execution of step S101, when it is detected that the vehicle is being used for off-road operations, the calibrated upstream NOx flow and the current downstream NOx flow of the vehicle can be obtained (for ease of distinction, the downstream NOx flow obtained when the vehicle is being used for off-road operations is referred to as the first downstream NOx flow), and the first downstream NOx flow is divided by the calibrated upstream NOx flow to obtain the SCR conversion efficiency of the vehicle at this time.

[0073] It should be noted that the upstream NOx flow rate is pre-calibrated using the original equipment and can be calibrated according to the actual application. This embodiment of the invention does not limit the calibration.

[0074] It should also be noted that the first downstream NOx flow rate when the vehicle is traveling off-road can be collected by the downstream NOx sensor.

[0075] S102: Determine whether the SCR conversion efficiency is less than the preset SCR conversion efficiency. If the SCR conversion efficiency is less than the preset SCR conversion efficiency, proceed to step S103.

[0076] In this embodiment of the invention, currently, if the SCR conversion efficiency of the entire vehicle is too low, an SCR removal fault will be reported. However, due to engine instability, upstream NOx flow may drift, resulting in a false SCR removal fault report. In other words, even if the SCR conversion efficiency is too low, it doesn't necessarily mean an SCR removal fault; it could also be due to engine drift. Therefore, to avoid false SCR removal fault reports, if the SCR conversion efficiency is determined to be low, further detection can be performed to check for engine drift.

[0077] Specifically, a preset SCR conversion efficiency can be set in advance according to the actual application situation, and it can be determined whether the previously calculated SCR conversion efficiency is less than the preset SCR conversion efficiency. If the SCR conversion efficiency is not less than the preset SCR conversion efficiency, the process can continue to return to step S101. If the SCR conversion efficiency is less than the preset SCR conversion efficiency, in order to avoid false alarms of SCR removal fault, the SCR removal fault will not be reported first. Step S103 and its subsequent steps can be executed first to determine whether the engine of the whole vehicle is currently experiencing original displacement drift.

[0078] S103: Determine whether original drift detection has been performed in the driving cycle of the whole vehicle; if no original drift detection has been performed in the driving cycle of the whole vehicle, proceed to step S104; if original drift detection has been performed in the driving cycle of the whole vehicle, proceed to step S110.

[0079] In this embodiment of the invention, since the engine's original exhaust drift detection is only performed once during the vehicle's driving cycle, when it is determined that the SCR conversion efficiency is less than the preset SCR, the original exhaust drift detection status of the entire vehicle can be obtained. Based on this original exhaust drift detection status, it can be determined whether the original exhaust drift detection has been performed during the vehicle's driving cycle. If the original exhaust drift detection has been performed during the vehicle's driving cycle, then there is no need to perform the original exhaust drift detection again, and the SCR removal fault can be directly output, i.e., step S110 is executed. If the original exhaust drift detection has not been performed during the vehicle's driving cycle, then step S104 is executed to determine whether the vehicle's engine meets the original exhaust drift detection conditions, so that if it is determined that the engine meets the original exhaust drift detection conditions, the original exhaust drift detection strategy is executed.

[0080] It is worth noting that the original drift detection status is used to characterize whether original drift detection has been performed in the driving cycle of the whole vehicle; the original drift detection status can be 1 or 0; the driving cycle of the whole vehicle is the complete process of the whole vehicle completing ignition, running (if there is a fault in the vehicle, it should be detectable), and shutting down.

[0081] Optionally, the process of determining whether an original drift detection has been performed in the driving cycle of the vehicle based on the original drift detection state can be as follows: determine whether the original drift detection state is 0; if the original drift detection state is 0, determine that no original drift detection has been performed in the driving cycle of the vehicle; if the original drift detection state is not 0, that is, the original drift detection state is 1, determine that an original drift detection has been performed in the driving cycle of the vehicle.

[0082] S104: Determine whether the engine of the vehicle meets the original drift detection conditions; if the engine meets the original drift detection conditions, proceed to step S105.

[0083] During the specific execution of step S104, if it is determined that no original drift detection has been performed in the driving cycle of the whole vehicle, the whole vehicle information can be obtained. Then, it can be determined whether the engine of the whole vehicle meets the original drift detection conditions based on the whole vehicle information. If it is determined that the engine meets the original drift detection conditions, step S105 can be continued.

[0084] Furthermore, in this embodiment of the invention, if it is determined that the engine does not meet the original drift detection conditions, the current time of the engine can be further obtained, and it can be detected in real time whether a preset time has elapsed since the current time, that is, whether there is a preset time interval difference from the current time; if there is a preset time interval difference from the current time of the engine, it is re-determined whether the engine meets the original drift detection conditions; if the engine still does not meet the original drift detection conditions, no message indicating SCR removal failure is output; if the engine meets the original drift detection conditions, step S105 is executed.

[0085] It is worth noting that the preset time interval is equal to the time difference between the preset time and the current time.

[0086] It should be noted that the vehicle information includes at least information such as whether the NOx sensor is effective and the current operating mode of the engine. The specific content of the vehicle information can be obtained according to the actual application, and is not limited in this embodiment of the invention.

[0087] It should also be noted that the NOx sensor can be a downstream NOx sensor, but this embodiment of the invention does not limit it.

[0088] Optionally, the process of determining whether the engine of the vehicle meets the original emission drift detection conditions can be as follows: determine whether the vehicle information indicates that the NOx sensor is effective and whether it indicates that the engine's operating mode is the target operating mode; if the vehicle information indicates that the NOx sensor is effective and indicates that the engine's operating mode is the target operating mode, determine that the engine meets the original emission drift detection conditions; if the vehicle information indicates that the NOx sensor is ineffective and / or indicates that the engine's operating mode is not the target operating mode, determine that the engine does not meet the original emission drift detection conditions.

[0089] It should be noted that the target operating mode of the engine can be set according to the actual application, but this embodiment of the invention does not limit it.

[0090] S105: Execute the original row drift detection strategy to determine the original row drift coefficient.

[0091] In this embodiment of the invention, the applicant has discovered that when there is ammonia stored in the SCR of the vehicle, the upstream NOx flow rate and the downstream NOx flow rate of the vehicle are not equal. Therefore, if it is determined that the engine meets the original exhaust drift detection conditions, the ammonia stored in the SCR can be emptied first, so that after the ammonia is emptied, the original exhaust drift coefficient can be further determined, and the original exhaust drift coefficient can be used to determine whether the engine has experienced original exhaust drift.

[0092] In practical applications, once the engine meets the original exhaust drift detection conditions, urea injection can be stopped, and the time spent stopping urea injection can be accumulated. Currently, if the accumulated time of stopping urea injection reaches a certain value, it can be considered that the ammonia reservoir in the SCR has been completely emptied. However, our research has found that the process of emptying the ammonia reservoir is also affected by the SCR exhaust temperature. The higher the SCR exhaust temperature and the higher the calibrated upstream NOx flow rate, the faster the ammonia reservoir in the SCR is emptied, and the shorter the time required. Therefore, the ammonia reservoir emptying rate can be determined by the SCR exhaust temperature and the calibrated upstream NOx flow rate, and the ammonia reservoir in the SCR can be emptied based on the ammonia reservoir emptying rate to achieve the goal of completely emptying the ammonia reservoir in the SCR. When the ammonia reservoir in the SCR is emptied, the upstream NOx flow rate of the engine is consistent, that is, the actual upstream NOx flow rate of the engine is equal to the downstream NOx flow rate. Therefore, judging whether the engine has experienced original exhaust drift based on the upstream NOx flow rate and the downstream NOx flow rate (the third downstream NOx flow rate) at this time can, to some extent, eliminate the possibility of false alarms for SCR removal faults.

[0093] Optionally, the process of executing the original exhaust drift detection strategy and determining the original exhaust drift coefficient can be as follows: If the engine meets the original exhaust drift detection conditions, stop injecting urea and accumulate the urea injection time; obtain the SCR exhaust temperature and determine the ammonia storage emptying rate based on the SCR exhaust temperature and the calibrated upstream NOx flow rate; empty the ammonia storage in the SCR based on the ammonia storage emptying rate and record the target time required to empty the ammonia storage in the SCR; when the accumulated urea injection time reaches a first preset time limit and the target time is greater than a second preset time limit, determine that the ammonia storage emptying is completed; when the ammonia storage emptying is completed, continue to stop urea injection and obtain the third downstream NOx flow rate of the entire vehicle; determine the original exhaust drift coefficient based on the calibrated upstream NOx flow rate and the third downstream NOx flow rate.

[0094] In some embodiments, a corresponding ammonia storage emptying rate table can be preset so that the ammonia storage emptying rate corresponding to the SCR discharge temperature and the upstream NOx flow rate can be queried based on the SCR discharge temperature and the calibration upstream NOx flow rate.

[0095] Optionally, the process of determining the original discharge drift coefficient based on the calibrated upstream NOx flow rate and the third downstream NOx flow rate can be as follows: based on a preset operating range, integrate the calibrated upstream NOx flow rate and the third downstream NOx flow rate using a preset integration window; when it is detected that the mass obtained by integrating the calibrated upstream NOx flow rate in the preset integration window reaches a preset mass, determine that the preset integration window is complete; obtain the upstream NOx mass corresponding to the calibrated upstream NOx flow rate and the downstream NOx mass corresponding to the third downstream NOx flow rate when the preset integration window is complete; calculate the original discharge drift coefficient based on the upstream NOx mass and the downstream NOx mass.

[0096] In practical applications, a stable preset operating condition range can be set so that after the ammonia reservoir in the SCR is emptied, urea injection can be stopped. At this time, the downstream NOx flow rate of the whole vehicle collected by the downstream NOx sensor (for easy distinction, the downstream NOx flow rate collected when the ammonia reservoir is emptied and urea injection stops is called the third downstream NOx flow rate) can be used as the actual original exhaust value, and the calibrated upstream NOx flow rate can be used as the calibrated theoretical value. Within the stable preset operating condition range, the calibrated upstream NOx flow rate is integrated by the integrator in the preset integration window. When the accumulated mass reaches the preset mass, the preset integration window can be considered to be completed. At this time, the corresponding original exhaust drift coefficient can be calculated based on the mass corresponding to the calibrated upstream NOx flow rate accumulated when the preset integration serial port is completed and the mass corresponding to the third downstream NOx flow rate, according to formula (1). Formula (1) is shown below.

[0097]

[0098] Where fac is the original row drift coefficient, M NOxDs M represents the mass corresponding to the third downstream NOx flow rate. NOxUs To calibrate the quality corresponding to the upstream NOx flow rate.

[0099] It should be noted that the preset working condition range can be the common working conditions of non-road machinery, and can be set according to actual applications. This embodiment of the invention does not limit this.

[0100] In summary, under stable preset operating conditions, after stopping urea injection for a certain period of time, the ammonia reservoir in the SCR is emptied. At this time, the upstream and downstream NOx values ​​are consistent, meaning that the calibrated upstream NOx flow rate is consistent with the third downstream NOx flow rate. Therefore, when there is a possibility of SCR removal failure, stopping urea injection and using the third downstream NOx as a benchmark to calculate the original exhaust drift coefficient, and judging whether the engine has experienced original exhaust drift based on the original exhaust drift coefficient, can accurately eliminate false alarms of SCR removal failure.

[0101] Furthermore, by calculating the original drift coefficient within a stable preset operating range and performing original drift diagnosis based on the calculated original drift coefficient, the situation of severe vibration in non-road operating conditions can be excluded, making the original drift detection more accurate and thus ensuring the accuracy of SCR removal fault reporting.

[0102] Furthermore, in this embodiment of the invention, when it is determined that the engine meets the original drift detection conditions, the engine can be controlled to start timing, and the original drift detection strategy can be executed simultaneously. The time for executing the original drift detection strategy is accumulated. If the accumulated time for executing the original drift detection strategy exceeds a third preset time limit, the original drift detection strategy can be exited directly to avoid the original drift detection time being too long.

[0103] Furthermore, after executing the original drift detection strategy, that is, after performing the original drift detection, the original drift detection status can be changed from 0 to 1 to mark that the original drift detection has been performed in the driving cycle of the whole vehicle.

[0104] S106: Determine whether the engine has experienced original displacement drift based on the original displacement drift coefficient. If the engine has experienced original displacement drift based on the original displacement drift coefficient, proceed to step S107; if the engine has not experienced original displacement drift based on the original displacement drift coefficient, proceed to step S110.

[0105] During the specific execution of step S106, a corresponding preset original drift coefficient can be set in advance so that after the original drift coefficient is calculated, it can be determined whether the original drift coefficient is greater than the preset original drift coefficient; if the original drift coefficient is greater than the preset original drift coefficient, it is determined that the engine has experienced original drift; if the original drift coefficient is not greater than the preset original drift coefficient, it is determined that the engine has experienced non-original drift.

[0106] S107: Correct the calibrated upstream NOx flow rate using the original exhaust drift coefficient, obtain the second downstream NOx flow rate of the vehicle, and calculate the target SCR conversion efficiency based on the second downstream NOx flow rate and the corrected calibrated upstream NOx flow rate.

[0107] In the specific execution of step S107, if it is determined that the engine has experienced original exhaust drift, the original exhaust drift coefficient can be output and multiplied by the calibration upstream NOx flow rate to correct the calibration upstream NOx flow rate. After correcting the calibration upstream NOx flow rate, the downstream NOx flow rate at this time is collected again through the downstream NOx sensor (for ease of distinction, the downstream NOx flow rate collected at this time is called the second downstream NOx flow rate), and the second downstream NOx flow rate is divided by the corrected calibration upstream NOx flow rate to obtain the target SCR conversion efficiency.

[0108] S108: Determine whether the target SCR conversion efficiency is less than the preset SCR conversion efficiency; if the target SCR conversion efficiency is not less than the preset SCR conversion efficiency, proceed to step S109; if the target SCR conversion efficiency is less than the preset SCR conversion efficiency, proceed to step S110.

[0109] During the specific execution of step S108, after recalculating the target SCR conversion efficiency using the corrected calibration upstream NOx flow, the target SCR conversion efficiency can be compared with the preset SCR conversion efficiency again. If the target SCR conversion efficiency is not less than the preset SCR conversion efficiency, it means that no SCR removal fault has occurred. Then step S109 can be executed to avoid reporting an SCR removal fault, thereby avoiding false SCR removal fault reports. If the target SCR conversion efficiency is still less than the preset SCR conversion efficiency, it means that an SCR removal fault has indeed occurred. Then step S110 can be executed to report an SCR removal fault, so that users can understand the current SCR removal fault situation in a timely manner.

[0110] S109: Determine that the engine has not experienced an SCR removal fault, and do not output a message indicating an SCR removal fault.

[0111] S110: Determine that the engine has experienced an SCR removal fault, and output a message characterizing the SCR removal fault.

[0112] During the specific execution of step S110, if the SCR conversion efficiency is lower than the preset SCR conversion efficiency, and the original exhaust drift diagnosis has been performed in the driving cycle of the whole vehicle / it is determined that the engine has not experienced original exhaust drift according to the original exhaust drift coefficient / the target SCR conversion efficiency is lower than the preset SCR conversion efficiency, then it can be determined that an SCR removal fault has indeed occurred. At this time, a message characterizing the SCR removal fault can be output so that the user can understand the current situation of the SCR removal fault in a timely manner.

[0113] This invention provides a method for identifying and handling engine exhaust drift. When the vehicle is detected to be operating off-road, it can first determine whether the current SCR conversion efficiency is low. If the current SCR conversion efficiency is determined to be low, to avoid false alarms of SCR removal faults, it can first determine whether exhaust drift detection has been performed during the vehicle driving cycle. If exhaust drift detection has not been performed during the vehicle driving cycle, and the engine meets the exhaust drift detection requirements, an exhaust drift detection strategy can be executed to determine the exhaust drift coefficient. If exhaust drift is determined to have occurred based on the exhaust drift coefficient, it indicates that the engine's upstream NOx flow rate has shifted. The exhaust drift coefficient can be used to correct the upstream NOx flow rate, so that the corrected upstream NOx flow rate and downstream NOx flow rate (third downstream NOx flow rate) can be used to recalculate the SCR conversion efficiency (target SCR conversion efficiency). The recalculated SCR conversion efficiency can then be used to determine whether an SCR removal fault has occurred, making SCR removal fault diagnosis more accurate and ensuring the accuracy of SCR removal fault reporting.

[0114] To better understand this invention, the following explanation uses examples, such as... Figure 2 As shown.

[0115] A1: When the vehicle is in operation off-road, obtain the first downstream NOx flow rate of the vehicle at this time, and divide the first downstream NOx flow rate by the calibrated upstream NOx flow rate to obtain the SCR conversion efficiency.

[0116] A2: Determine if the SCR conversion efficiency is less than the preset SCR conversion efficiency; if the SCR conversion efficiency is less than the preset SCR forwarding efficiency, in order to avoid false alarms of SCR removal failure, do not report the SCR removal failure first, and you can execute A3 first.

[0117] A3: By determining whether the current original drift detection status of the vehicle is 0, it can be determined whether original drift detection has been performed in the vehicle's driving cycle. If it is 0, it is determined that original drift detection has not been performed in the vehicle's driving cycle, and A4 can be executed. If it is not 0, it is determined that original drift detection has been performed in the vehicle's driving cycle, and it can be determined that the vehicle has indeed experienced an SCR removal fault. A16 can then be executed to report the SCR removal fault.

[0118] A4: Obtain the vehicle information and determine whether the vehicle information indicates that the NOx sensor is valid and whether the engine's operating mode is the target operating mode; if the vehicle information indicates that the NOx sensor is invalid and / or indicates that the engine's operating mode is not the target operating mode, determine that the engine does not meet the original exhaust drift detection conditions and execute A5; if the vehicle information indicates that the NOx sensor is valid and indicates that the engine's operating mode is the target operating mode, determine that the engine meets the original exhaust drift detection conditions and execute A7.

[0119] A5: Obtain the current time of the engine;

[0120] A6: When the current time of the engine differs from the current time by a preset time interval, reacquire the vehicle information and re-determine whether the vehicle information indicates that the NOx sensor is valid and whether the engine's operating mode is the target operating mode; if the vehicle information indicates that the NOx sensor is invalid and / or indicates that the engine's operating mode is not the target operating mode, determine that the engine does not meet the original exhaust drift detection conditions and execute A18; if the vehicle information indicates that the NOx sensor is valid and indicates that the engine's operating mode is the target operating mode, determine that the engine meets the original exhaust drift detection conditions and execute A7.

[0121] A7: Stop spraying urea and accumulate the time spent without spraying urea.

[0122] A8: Obtain the SCR discharge temperature, and based on the SCR discharge temperature and the calibrated upstream NOx flow rate, query the ammonia storage emptying rate table to determine the ammonia storage emptying rate.

[0123] A9: Empty the ammonia storage in the SCR based on the ammonia storage emptying rate, and record the target time required to empty the ammonia storage in the SCR. When the cumulative time for injecting urea reaches the first preset time limit and the target time is greater than the second preset time limit, it is determined that the ammonia storage emptying is completed.

[0124] A10: When the ammonia storage is emptied, continue to stop urea injection, obtain the third downstream NOx flow rate of the whole vehicle, and integrate the calibrated upstream NOx flow rate and the third downstream NOx flow rate respectively using a preset integration window based on the preset operating condition range.

[0125] A11: When it is detected that the quality obtained by integrating the calibrated upstream NOx flow rate in the preset integration window reaches the preset quality, the preset integration window is determined to be completed.

[0126] A12: Obtain the upstream NOx mass corresponding to the calibrated upstream NOx flow rate and the downstream NOx mass corresponding to the third downstream NOx flow rate when the preset integration window is completed, and divide the downstream NOx mass corresponding to the third downstream NOx flow rate by the mass corresponding to the calibrated upstream NOx flow rate to obtain the original discharge drift coefficient.

[0127] A13: Determine whether the engine has experienced original displacement drift based on the original displacement drift coefficient; if the engine has not experienced original displacement drift, execute A14; if the engine has experienced original displacement drift, execute A17.

[0128] A14: The original discharge drift coefficient is used to correct the calibrated upstream NOx flow rate.

[0129] A15: Obtain the second downstream NOx flow of the whole vehicle, and calculate the target SCR conversion efficiency based on the second downstream NOx flow and the corrected calibrated upstream NOx flow, so as to achieve the purpose of resetting the SCR conversion efficiency.

[0130] A16: Determine if the target SCR conversion efficiency is less than the preset SCR conversion efficiency; if it is less, execute A17; if it is not less, execute A18.

[0131] A17: Outputs a message indicating a fault in SCR removal.

[0132] A18: Do not output messages indicating SCR removal failure.

[0133] Based on the engine exhaust drift identification and processing method provided in the above embodiments of the present invention, correspondingly, the present invention also provides an engine exhaust drift identification and processing device, such as... Figure 3 As shown, the device includes:

[0134] SCR conversion efficiency calculation unit 31 is used to obtain the first downstream NOx flow of the whole vehicle when the whole vehicle is in operation in off-road operation, and to calculate the SCR conversion efficiency based on the calibrated upstream NOx flow and the first downstream NOx flow.

[0135] The first judgment unit 32 is used to determine whether the engine of the vehicle meets the original drift detection conditions if the SCR conversion efficiency is less than the preset SCR conversion efficiency and no original drift detection has been performed in the driving cycle of the whole vehicle.

[0136] Execution unit 33 is used to execute the original exhaust drift detection strategy and determine the original exhaust drift coefficient if the engine meets the original exhaust drift detection conditions;

[0137] Correction unit 34 is used to correct the calibration upstream NOx flow rate using the original exhaust drift coefficient if it is determined that the engine has experienced original exhaust drift based on the original exhaust drift coefficient.

[0138] The target SCR conversion efficiency calculation unit 35 is used to obtain the second downstream NOx flow of the whole vehicle and calculate the target SCR conversion efficiency based on the second downstream NOx flow and the corrected calibrated upstream NOx flow.

[0139] The first non-output unit 36 ​​is used to determine that the engine has not experienced an SCR removal fault if the target SCR conversion efficiency is not less than the preset SCR conversion efficiency, and not to output a message indicating an SCR removal fault.

[0140] The specific principles and execution processes of each unit in the engine exhaust drift identification and processing device disclosed in the above embodiments of the present invention are the same as those of the engine exhaust drift identification and processing method disclosed in the above embodiments of the present invention. Please refer to the corresponding parts of the engine exhaust drift identification and processing method disclosed in the above embodiments of the present invention, and they will not be repeated here.

[0141] This invention provides an engine exhaust drift identification and processing device. When the vehicle is detected to be operating off-road, it can first determine whether the current SCR conversion efficiency is low. If the current SCR conversion efficiency is determined to be low, to avoid false alarms of SCR removal faults, it can first determine whether exhaust drift detection has been performed during the vehicle driving cycle. If exhaust drift detection has not been performed during the vehicle driving cycle, and the engine meets the exhaust drift detection requirements, an exhaust drift detection strategy can be executed to determine the exhaust drift coefficient. If exhaust drift is determined to have occurred based on the exhaust drift coefficient, it indicates that the engine's upstream NOx flow rate has deviated. The exhaust drift coefficient can be used to correct the upstream NOx flow rate, so that the corrected upstream NOx flow rate and downstream NOx flow rate (third downstream NOx flow rate) can be used to recalculate the SCR conversion efficiency (target SCR conversion efficiency). The recalculated SCR conversion efficiency can then be used to determine whether an SCR removal fault has occurred, making SCR removal fault diagnosis more accurate, thus ensuring the accuracy of SCR removal fault reporting.

[0142] Optionally, the engine exhaust drift identification and processing device provided in this embodiment of the invention further includes:

[0143] The output unit is configured to output a message indicating an SCR removal fault if: a drive cycle of the vehicle has been performed for original exhaust drift diagnosis; or, the original exhaust drift coefficient determines that the engine has not experienced original exhaust drift; or, the target SCR conversion efficiency is less than a preset SCR conversion efficiency.

[0144] Optionally, the engine exhaust drift identification and processing device provided in this embodiment of the invention further includes:

[0145] The original exhaust drift state acquisition unit is used to acquire the original exhaust drift detection state of the whole vehicle if the SCR conversion efficiency is less than the preset SCR conversion efficiency.

[0146] The second judgment unit is used to determine whether the original row drift detection state is 0;

[0147] The first determining unit is used to determine that no original drift detection has been performed in the driving cycle of the vehicle if the original drift detection state is 0.

[0148] The second determining unit is used to determine that an original drift detection has been performed in the driving cycle of the vehicle if the original drift detection state is not 0.

[0149] Optionally, the engine exhaust drift identification and processing device provided in this embodiment of the invention further includes:

[0150] The current time acquisition unit is used to acquire the current time of the engine if the engine does not meet the original drift detection conditions;

[0151] The third judgment unit is used to re-determine whether the engine meets the original drift detection conditions when the current time of the engine differs from the current time of the engine by a preset time interval.

[0152] The second non-output unit is used to not output a message indicating SCR removal failure if the engine still does not meet the original drift detection conditions.

[0153] The return execution unit is used to return to the execution unit if the engine meets the original drift detection conditions.

[0154] Optionally, the first judgment unit includes:

[0155] The vehicle information acquisition unit is used to acquire the vehicle information if the SCR conversion efficiency is less than the preset SCR conversion efficiency and no original drift detection has been performed in the driving cycle of the vehicle.

[0156] The first judgment subunit is used to determine whether the vehicle information indicates that the NOx sensor is effective and whether it indicates that the engine's operating mode is the target operating mode;

[0157] The third determining unit is used to determine that the engine meets the original emission drift detection conditions if the vehicle information indicates that the NOx sensor is effective and indicates that the engine's operating mode is the target operating mode.

[0158] The fourth determining unit is used to determine that the engine does not meet the original emission drift detection conditions if the vehicle information indicates that the NOx sensor is invalid, and / or indicates that the engine's operating mode is not the target operating mode.

[0159] Optional execution units include:

[0160] The injection stop unit is used to stop injecting urea if the engine meets the original drift detection conditions, and to accumulate the time when urea injection is stopped.

[0161] The fifth determining unit is used to acquire the SCR exhaust temperature and determine the ammonia storage emptying rate based on the SCR exhaust temperature and the calibrated upstream NOx flow rate.

[0162] A recording unit is used to empty the ammonia storage in the SCR based on the ammonia storage emptying rate, and to record the target time required to empty the ammonia storage in the SCR.

[0163] The sixth determining unit is used to determine that the ammonia storage has been emptied when the cumulative time of urea injection reaches the first preset time limit and the target time is greater than the second preset time limit.

[0164] The third downstream NOx flow acquisition unit is used to continue stopping urea injection and acquire the third downstream NOx flow of the whole vehicle when the ammonia storage is emptied.

[0165] The seventh determining unit is used to determine the original discharge drift coefficient based on the calibrated upstream NOx flow rate and the third downstream NOx flow rate.

[0166] Optionally, the seventh determining unit includes:

[0167] An integration unit is used to integrate the calibrated upstream NOx flow and the third downstream NOx flow respectively based on a preset operating condition range and using a preset integration window.

[0168] The eighth determining unit is used to determine that the preset integration window is completed when it is detected that the quality obtained by integrating the calibrated upstream NOx flow in the preset integration window reaches the preset quality.

[0169] The quality acquisition unit is used to acquire the upstream NOx quality corresponding to the calibrated upstream NOx flow and the downstream NOx quality corresponding to the third downstream NOx flow when the preset integration window is completed.

[0170] The coefficient calculation unit is used to calculate the original discharge drift coefficient based on the upstream NOx mass and the downstream NOx mass.

[0171] Optionally, the engine exhaust drift identification and processing device provided in this embodiment of the invention further includes:

[0172] The fourth judgment unit is used to determine whether the original row drift coefficient is greater than the preset original row drift coefficient;

[0173] The ninth determining unit is used to determine that the engine has experienced original displacement drift if the original displacement drift coefficient is greater than the preset original displacement drift coefficient;

[0174] The tenth determining unit is used to determine that the engine has experienced non-original drift if the original drift coefficient is not greater than the preset original drift coefficient.

[0175] 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.

[0176] 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.

[0177] 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.

[0178] The above are merely preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for identifying and processing engine exhaust drift, characterized in that, The method includes: When the vehicle is in operation off-road, the first downstream NOx flow of the vehicle is obtained, and the SCR conversion efficiency is calculated based on the calibrated upstream NOx flow and the first downstream NOx flow. If the SCR conversion efficiency is less than the preset SCR conversion efficiency, and no original exhaust drift detection has been performed in the driving cycle of the whole vehicle, determine whether the engine of the whole vehicle meets the original exhaust drift detection conditions. If the engine meets the original exhaust drift detection conditions, execute the original exhaust drift detection strategy to determine the original exhaust drift coefficient; If it is determined that the engine has experienced original exhaust drift based on the original exhaust drift coefficient, the original exhaust drift coefficient is used to correct the calibrated upstream NOx flow rate; Obtain the second downstream NOx flow rate of the entire vehicle, and calculate the target SCR conversion efficiency based on the second downstream NOx flow rate and the corrected calibrated upstream NOx flow rate; If the target SCR conversion efficiency is not less than the preset SCR conversion efficiency, it is determined that the engine has not experienced an SCR removal fault, and no message indicating an SCR removal fault is output. Wherein, if the engine meets the original exhaust drift detection conditions, the original exhaust drift detection strategy is executed to determine the original exhaust drift coefficient, including: If the engine meets the original drift detection conditions, stop injecting urea and accumulate the time when urea injection is stopped; Obtain the SCR exhaust temperature, and determine the ammonia storage emptying rate based on the SCR exhaust temperature and the calibrated upstream NOx flow rate; Empty the ammonia storage in the SCR based on the ammonia storage emptying rate, and record the target time required to empty the ammonia storage in the SCR; When the cumulative time for stopping urea injection reaches the first preset time limit, and the target time is greater than the second preset time limit, the ammonia storage is determined to be emptied. When the ammonia storage is emptied, urea injection is stopped again, and the third downstream NOx flow rate of the whole vehicle is obtained; The original discharge drift coefficient is determined based on the calibrated upstream NOx flow rate and the third downstream NOx flow rate; The method further includes determining whether the original row drift coefficient is greater than a preset original row drift coefficient; If the original displacement drift coefficient is greater than the preset original displacement drift coefficient, it is determined that the engine has experienced original displacement drift; If the original displacement drift coefficient is not greater than the preset original displacement drift coefficient, it is determined that the engine has not experienced original displacement drift.

2. The method according to claim 1, characterized in that, The method further includes: If a drive cycle of the vehicle has been performed to detect original exhaust drift, or if the original exhaust drift coefficient indicates that the engine has not experienced original exhaust drift, or if the target SCR conversion efficiency is less than the preset SCR conversion efficiency, a message indicating an SCR removal fault is output.

3. The method according to claim 1, characterized in that, The description also includes: If the SCR conversion efficiency is less than the preset SCR conversion efficiency, the original exhaust drift detection status of the whole vehicle is obtained; Determine whether the original row drift detection state is 0; If the original drift detection status is 0, it is determined that no original drift detection has been performed in the driving cycle of the vehicle. If the original drift detection status is not 0, it is determined that the original drift detection has been performed in the driving cycle of the vehicle.

4. The method according to claim 1, characterized in that, The method further includes: If the engine does not meet the original drift detection conditions, obtain the current time of the engine; When the current time of the engine differs from the current time of the engine by a preset time interval, the engine is re-evaluated to determine whether it meets the original drift detection conditions. If the engine still does not meet the original drift detection conditions, no message indicating SCR removal failure will be output. If the engine meets the original exhaust drift detection conditions, the original exhaust drift detection strategy is executed to determine the original exhaust drift coefficient.

5. The method according to claim 1, characterized in that, If the SCR conversion efficiency is less than the preset SCR conversion efficiency, and no original exhaust drift detection has been performed during the vehicle's driving cycle, determine whether the vehicle's engine meets the original exhaust drift detection conditions, including: If the SCR conversion efficiency is less than the preset SCR conversion efficiency, and no original drift detection has been performed in the driving cycle of the whole vehicle, obtain the whole vehicle information. Determine whether the vehicle information indicates that the NOx sensor is effective and whether it indicates that the engine's operating mode is the target operating mode; If the vehicle information indicates that the NOx sensor is effective and indicates that the engine is operating in the target mode, then the engine is determined to meet the original emission drift detection conditions. If the vehicle information indicates that the NOx sensor is invalid, and / or indicates that the engine's operating mode is not the target operating mode, it is determined that the engine does not meet the original emission drift detection conditions.

6. The method according to claim 1, characterized in that, The determination of the original discharge drift coefficient based on the calibrated upstream NOx flow rate and the third downstream NOx flow rate includes: Based on a preset operating condition range, the calibrated upstream NOx flow and the third downstream NOx flow are integrated using a preset integration window; When it is detected that the quality obtained by integrating the calibrated upstream NOx flow rate in the preset integration window reaches the preset quality, it is determined that the preset integration window is completed; When the preset integration window is completed, the upstream NOx mass corresponding to the calibrated upstream NOx flow rate and the downstream NOx mass corresponding to the third downstream NOx flow rate are obtained. The original emission drift coefficient is calculated based on the upstream NOx mass and the downstream NOx mass.

7. An apparatus for identifying and processing exhaust drift in an engine for performing the method according to any one of claims 1-6, characterized in that, The device includes: The SCR conversion efficiency calculation unit is used to obtain the first downstream NOx flow of the vehicle when the vehicle is in operation off-road, and to calculate the SCR conversion efficiency based on the calibrated upstream NOx flow and the first downstream NOx flow. The first judgment unit is used to determine whether the engine of the vehicle meets the original drift detection conditions if the SCR conversion efficiency is less than the preset SCR conversion efficiency and no original drift detection has been performed in the driving cycle of the vehicle. The execution unit is used to execute the original exhaust drift detection strategy and determine the original exhaust drift coefficient if the engine meets the original exhaust drift detection conditions; The correction unit is used to correct the calibrated upstream NOx flow rate by using the original exhaust drift coefficient if it is determined that the engine has experienced original exhaust drift based on the original exhaust drift coefficient. The target SCR conversion efficiency calculation unit is used to obtain the second downstream NOx flow of the whole vehicle, and calculate the target SCR conversion efficiency based on the second downstream NOx flow and the corrected calibrated upstream NOx flow. The first non-output unit is used to determine that the engine has not experienced an SCR removal fault if the target SCR conversion efficiency is not less than the preset SCR conversion efficiency, and not to output a message indicating an SCR removal fault.

8. The apparatus according to claim 7, characterized in that, The device further includes: The output unit is configured to output a message indicating an SCR removal fault if: a drive cycle of the vehicle has been performed for original exhaust drift diagnosis; or, the original exhaust drift coefficient determines that the engine has not experienced original exhaust drift; or, the target SCR conversion efficiency is less than a preset SCR conversion efficiency.

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