A method and device for correcting original emission model NOx value, an engine and a vehicle

Abstract

Embodiments of the present application disclose a kind of original correction method, device, engine and vehicle of model NOx value.The correction method includes: obtaining the current working state of engine;According to current working state, judge whether to satisfy the correction condition of original model NOx value;If yes, obtain the first integral value of NOx value measured in the first preset time by downstream NOx sensor and the second integral value of NOx value in the first preset time in original model;According to the first integral value and the second integral value, determine correction coefficient;The correction coefficient is substituted into original model calibration pulse spectrum, and the NOx value in original model is corrected.The embodiments of the present application make full use of the real original exhaust of engine collected by the downstream NOx sensor of SCR device, adjust the NOx value of original model using the relationship between real original exhaust and model original exhaust, so that the NOx value of original model can be corrected under the influence of various factors, so as to be closer to the real value and improve product performance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of vehicles, in particular to a method and device for correcting original exhaust NOx value, an engine and a vehicle. BACKGROUND

[0002] The existing engine models with selective catalytic reduction (SCR) devices do not have nitrogen oxide (NOx) sensors upstream of the SCR input end, and the urea injection amount needs to be calculated and controlled by a NOx model, so the accuracy of the original exhaust NOx model directly affects the accuracy of the urea injection amount calculation. The current NOx model has poor adaptability to various engine boundaries and environmental factors. When the boundary changes too much, it will cause deviation in the calculation of original exhaust NOx, urea injection and SCR efficiency, and there is a risk of false alarm in the removal of post-processing crystallization and SCR. SUMMARY

[0003] The embodiments of the present application provide a method and device for correcting original exhaust NOx value, an engine and a vehicle, which make full use of the real original exhaust of the engine collected by the downstream NOx sensor of the engine SCR device, and adjust the original exhaust NOx value of the model by using the relationship between the real original exhaust and the model original exhaust, so that the original exhaust NOx value of the engine can be corrected under various factors, thereby being closer to the real value and improving the product performance.

[0004] According to an aspect of the present application, a method for correcting original exhaust NOx value is provided, which is applicable to an engine provided with a selective catalytic reduction (SCR) device, the SCR device comprising a downstream NOx sensor arranged at the output end of the SCR device, and the method comprising:

[0005] obtaining the current working state of the engine;

[0006] determining whether the correction condition of the original exhaust NOx value is met according to the current working state;

[0007] if yes, obtaining a first integral value of the NOx value measured by the downstream NOx sensor within a first preset time and a second integral value of the NOx value in the original exhaust model within the first preset time;

[0008] determining a correction coefficient according to the first integral value and the second integral value;

[0009] substituting the correction coefficient into the original exhaust model calibration map to correct the NOx value in the original exhaust model.

[0010] Optionally, after substituting the correction factor into the original emission model calibration map to correct the NOx value in the original emission model, the method further comprises:

[0011] According to the corrected NOx value, the urea injection amount of the SCR device is determined.

[0012] Optionally, the current working state of the engine is obtained, comprising:

[0013] The urea injection amount of the engine and the current ammonia storage state are obtained.

[0014] Optionally, the correction condition of the original emission model NOx value comprises:

[0015] The urea injection amount of the engine is zero and lasts for a second preset time;

[0016] The engine is currently in a non-ammonia storage state.

[0017] Optionally, the second preset time and the first preset time are the same time period.

[0018] Optionally, according to the first integral value and the second integral value, the correction factor is determined, comprising:

[0019] According to fac 修正 = NOx 传感器测量积分值 / NOx 模型积分值 The correction factor is calculated.

[0020] Wherein, NOx 传感器测量积分值 is the first integral value, and NOx 模型积分值 is the second integral value.

[0021] Optionally, substituting the correction factor into the original emission model calibration map to correct the NOx value in the original emission model comprises:

[0022] fac 修正 is multiplied by the calculated original emission model calibration map to correct the NOx value in the original emission model.

[0023] According to another aspect of the present application, a device for correcting the NOx value of the original emission model is provided, comprising:

[0024] An obtaining module is configured to obtain the current working state of the engine;

[0025] A judging module is configured to judge whether the correction condition of the original emission model NOx value is met according to the current working state;

[0026] an integration module configured to, when the determination module determines that the condition is met, obtain a first integral value of the NOx value measured by the downstream NOx sensor in a first preset time and a second integral value of the NOx value in the original emission model in the first preset time;

[0027] a correction coefficient determination module configured to determine a correction coefficient according to the first integral value and the second integral value;

[0028] a correction module configured to substitute the correction coefficient into the original emission model calibration map to correct the NOx value in the original emission model.

[0029] According to another aspect of the present application, there is provided an engine comprising the original emission model NOx value correction device described above, which is used in any of the original emission model NOx value correction methods described above.

[0030] According to another aspect of the present application, there is provided a vehicle comprising the engine described above.

[0031] The original emission model NOx value correction method provided by the embodiments of the present application is suitable for an engine provided with an SCR device, the SCR device comprising a downstream NOx sensor arranged at the output end of the SCR device, and the correction method comprises the following steps: first, obtaining the current working state of the engine; second, judging whether the correction condition of the original emission model NOx value is met according to the current working state; third, if the correction condition is met, obtaining a first integral value of the NOx value measured by the downstream NOx sensor in a first preset time and a second integral value of the NOx value in the original emission model in the first preset time; fourth, determining a correction coefficient according to the first integral value and the second integral value; and fifth, substituting the correction coefficient into the original emission model calibration map to correct the NOx value in the original emission model. The technical solution of the embodiments of the present application uses the downstream NOx sensor of the SCR device to measure the real engine NOx value to correct the original engine NOx emission, and when the correction condition is met, the integral comparison between the engine NOx value measured by the downstream NOx sensor and the NOx model value is performed, so that the original emission model NOx value of the engine can be corrected to be closer to the real value under the influence of various factors, and the product performance is improved.

[0032] It should be understood that the description in this section is not intended to identify key or critical features of the embodiments of the present application or to limit the scope of the present application. Other features of the present application will become apparent from the following description. BRIEF DESCRIPTION OF DRAWINGS

[0033] In order to make the technical solutions in the embodiments of the present application clearer, the accompanying drawings needed in the embodiments will be briefly introduced below. Obviously, the accompanying drawings in the following description only show some embodiments of the present application, and all other embodiments obtained by those of ordinary skill in the art without any creative effort based on the accompanying drawings should fall within the protection scope of the present application.

[0034] Figure 1 Fig. 1 is a structural schematic diagram of an engine aftertreatment system;

[0035] Figure 2 Fig. 2 is a schematic diagram of the relationship between the NOx model value and the NOx value measured by a downstream NOx sensor when the original exhaust of the engine changes;

[0036] Figure 3 Fig. 3 is a flow schematic diagram of a correction method of the original exhaust model NOx value provided by the embodiment of the present application;

[0037] Figure 4 Fig. 4 is a flow schematic diagram of another correction method of the original exhaust model NOx value provided by the embodiment of the present application;

[0038] Figure 5 Fig. 5 is a schematic diagram of a correction device of the original exhaust model NOx value provided by the embodiment of the present application;

[0039] Figure 6 Fig. 6 is a schematic diagram of another correction device of the original exhaust model NOx value provided by the embodiment of the present application. DETAILED DESCRIPTION

[0040] In order to make the technical solutions in the embodiments of the present application clearer, the accompanying drawings needed in the embodiments will be briefly introduced below. Obviously, the accompanying drawings in the following description only show some embodiments of the present application, and all other embodiments obtained by those of ordinary skill in the art without any creative effort based on the accompanying drawings should fall within the protection scope of the present application.

[0041] It has to be noted that the terms "first", "second", etc. as used in the description and the claims and the above figures of the present application are used to distinguish between similar objects, not necessarily described by their priority or chronology. The skilled person understands that the data thus used can be interchanged, where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than the one illustrated or described herein. Furthermore, the terms "comprising" and "having" and any variations thereof, are intended to cover a non-exclusive inclusion, for example, a process, method, system, product, or apparatus that comprises a list of steps or units not necessarily limited to those explicitly listed, but can include other steps or units not expressly listed or inherent to such process, method, product, or apparatus.

[0042] Figure 1 is a schematic view of a structure of an engine aftertreatment system, referring to Figure 1 The engine aftertreatment system comprises a filter (1) along an exhaust gas flow direction (2) from an engine (3) to an exhaust gas treatment device (4). Figure 1The exhaust treatment system is provided with a diesel oxidation catalyst (DOC) 10, a diesel particulate filter (DPF) 20, a selective catalytic reduction (SCR) device 30 and an ammonia slip catalyst (ASC) 40 arranged in sequence (indicated by arrows), wherein the DOC is a device for converting carbon monoxide (CO) and hydrocarbons (HC) in engine exhaust into harmless water (H2O) and carbon dioxide (CO2) through an oxidation reaction, while reducing the soluble organic components in particulate matter; the DPF is arranged behind the DOC and can capture particulate emissions before they enter the atmosphere, thereby reducing particulate emissions; the SCR is a treatment process for NOx in exhaust emissions, i.e., under the action of a catalyst, ammonia or urea is sprayed to reduce NOx in the exhaust into nitrogen (N2) and H2O; the main function of the ASC is to eliminate excess or escaped ammonia (NH3): excess NH3 is oxidized into N2, N2O and NOx; at the same time, the reaction of NOx and NH3 is catalyzed into N2. The exhaust treatment system further includes a DOC front temperature sensor 50 arranged on the exhaust pipe before the DOC to measure the exhaust temperature before the DOC; a DPF front temperature sensor 60 arranged on the exhaust pipe before the DPF to measure the exhaust temperature before the DPF, and estimate the amount of carbon deposition and the amount of HC injection during regeneration; an SCR front temperature sensor 70 arranged on the exhaust pipe before the SCR to measure the exhaust temperature before the SCR, and calculate the urea spraying temperature and the average temperature of the SCR tank; an SCR rear temperature sensor 80 arranged on the exhaust pipe after the SCR to measure the exhaust temperature after the SCR, and calculate the average temperature of the SCR tank; and an SCR downstream NOx sensor 90 arranged on the exhaust pipe after the SCR to measure the NOx value after the SCR, and calculate the efficiency of the SCR.

[0043] Figure 2 A schematic diagram showing the relationship between the NOx model value and the NOx value measured by the downstream NOx sensor when the original engine emission changes, wherein the original engine emission model can be pre-calibrated according to the actual engine, and when the original engine emission is unbiased, the NOx model value and the measured value of the downstream NOx sensor are not much different. When the original engine emission NOx value deviates due to various factors, the NOx model value remains unchanged, but the original emission measurement value of the downstream NOx sensor changes with the change of the real original emission of the engine.

[0044] Based on this, the embodiment of the application provides a correction method for the original emission model NOx value, Figure 3A flowchart of a correction method of an original exhaust model NOx value provided by an embodiment of the present application is shown in the figure. The correction method is suitable for an engine provided with a selective catalytic reduction (SCR) device. The SCR device comprises a downstream NOx sensor arranged downstream of an output end of the SCR device. The reference Figure 3 The correction method comprises the following steps.

[0045] S110, obtaining a current working state of the engine.

[0046] Optionally, obtaining the current working state of the engine comprises the following steps.

[0047] Obtaining a urea injection amount of the engine and a current ammonia storage state.

[0048] When the urea injection amount of the engine is zero, the NOx value measured by the downstream NOx sensor is the original exhaust of the engine. Therefore, when the original exhaust of the engine increases, the NOx value measured by the downstream NOx sensor will increase; when the original exhaust of the engine decreases, the NOx value measured by the downstream NOx sensor will decrease. Therefore, in this embodiment, the original exhaust NOx of the engine is measured by the downstream NOx sensor when the urea injection amount of the engine is zero. The current ammonia storage state refers to whether there is urea storage.

[0049] S120, determining whether a correction condition of the original exhaust model NOx value is met according to the current working state.

[0050] It can be understood that if the correction condition of the original exhaust model NOx value is met, the subsequent steps are continued to realize the original exhaust model NOx value. If the correction condition of the original exhaust model NOx value is not met, the current correction can be ended, and whether the correction condition is met is determined again after a preset time.

[0051] Optionally, the correction condition of the original exhaust model NOx value comprises the following conditions.

[0052] The urea injection amount of the engine is zero and lasts for a second preset time;

[0053] The engine is currently in a non-ammonia storage state.

[0054] In a specific implementation, the second preset time can be designed according to actual conditions. In an embodiment, the second preset time can be set to 5 min to 10 min. The condition that the engine is in the non-ammonia storage state can be that the ambient temperature is relatively low, for example, below 180℃, at which time no reaction occurs and the influence of ammonia storage can be ignored, so that the engine is considered to be in the non-ammonia storage state. When the engine is in the ammonia storage state at a relatively high ambient temperature, the storage amount can be completely reacted after 4 min to 5 min.

[0055] S130, if yes, obtaining a first integral value of the NOx value measured by the downstream NOx sensor in a first preset time and a second integral value of the NOx value in the original exhaust model in the first preset time.

[0056] In implementation, the first preset time period can be designed according to actual conditions, for example, can be set to 5min-10min. In an embodiment, optionally, the second preset time is the same time period as the first preset time, so that the correction time is shortened and the process is simplified.

[0057] S140, determining a correction coefficient according to the first integral value and the second integral value.

[0058] After obtaining the first integral value and the second integral value, the correction coefficient can be determined according to the ratio of the first integral value and the second integral value. Optionally, the correction coefficient is determined according to the first integral value and the second integral value, including:

[0059] According to fac 修正 = NOx 传感器测量积分值 / NOx 模型积分值 Calculate the correction coefficient.

[0060] Wherein, NOx 传感器测量积分值 is the first integral value, and NOx 模型积分值 is the second integral value.

[0061] S150, substituting the correction coefficient into the original exhaust model calibration pulse spectrum to correct the NOx value in the original exhaust model.

[0062] Optionally, the correction coefficient is substituted into the original exhaust model calibration pulse spectrum to correct the NOx value in the original exhaust model, including:

[0063] fac 修正 is multiplied into the calculated original exhaust model calibration pulse spectrum to correct the NOx value in the original exhaust model.

[0064] Wherein, the original exhaust model calibration pulse spectrum can be calibrated by the corresponding engine using the engine test bench, and in implementation, reference can be made to the prior art, and the embodiment of the present application will not be described in detail.

[0065] The technical scheme of the embodiment of the present application uses the downstream NOx sensor of the SCR device to measure the real value of the engine NOx to correct the original exhaust of the engine, calculates the integral comparison of the engine NOx value measured by the downstream NOx sensor and the NOx model value when the correction condition is met, so that the original exhaust model NOx value of the engine can be corrected under the influence of various factors to be closer to the real value, and the product performance is improved.

[0066] It should be noted that the timing of the original exhaust model NOx value correction of the embodiments of the present application is not limited, and can be selected according to actual conditions in specific implementation, for example, in a certain embodiment, the correction can be performed periodically, for example, once every 30 hours, 50 hours, three days, a week, a month, or once per driving cycle, or the correction can be performed under severe conditions such as high humidity (humidity greater than 60%), high altitude, low temperature (below minus 5 degrees Celsius), or the correction time can be shortened (for example, 30 hours to 10 hours) under severe conditions.

[0067] Figure 4 Another flowchart of a method for correcting an original exhaust model NOx value provided by an embodiment of the present application is shown in FIG. 6. Figure 4 The method includes:

[0068] S210, obtaining a current working state of the engine.

[0069] S220, determining whether the correction condition of the original exhaust model NOx value is met according to the current working state.

[0070] S230, if yes, obtaining a first integral value of the NOx value measured by the downstream NOx sensor within a first preset time and a second integral value of the NOx value in the original exhaust model within the first preset time.

[0071] S240, determining a correction coefficient according to the first integral value and the second integral value.

[0072] S250, substituting the correction coefficient into the original exhaust model calibration map to correct the NOx value in the original exhaust model.

[0073] S260, determining the urea injection amount of the SCR device according to the corrected NOx value.

[0074] The original exhaust model NOx value is used for calculating and controlling the urea injection amount, and the corrected NOx value can effectively improve the accuracy of the urea injection amount and improve the performance of the aftertreatment system.

[0075] Figure 5 A correction device for an original exhaust model NOx value provided by an embodiment of the present application is shown in FIG. 7, and the correction device is used to execute the correction method provided by the embodiment shown in FIG. 6. Figure 3 The correction device includes: Figure 5

[0076] ​The acquisition module 1 is used to acquire the current working state of the engine; the judgment module 2 is used to judge whether the correction condition of the original emission model NOx value is met according to the current working state; the integral module 3 is used to acquire a first integral value of the NOx value measured by the downstream NOx sensor in a first preset time and a second integral value of the NOx value in the original emission model in the first preset time when the judgment module 2 judges that the correction condition of the original emission model NOx value is met; the correction coefficient determination module 4 is used to determine the correction coefficient according to the first integral value and the second integral value; and the correction module 5 is used to substitute the correction coefficient into the original emission model calibration map to correct the NOx value in the original emission model.

[0077] The original emission model NOx value correction device provided by the embodiment of the application is used to execute the original emission model NOx value correction method provided by any one of the above embodiments, has the same or corresponding technical effects, and details are not described herein.

[0078] Figure 6 Another original emission model NOx value correction device provided by the embodiment of the application is shown in a schematic diagram, and the correction device is used to execute the correction method provided by the embodiment shown in the above Figure 4 Figure 6 Optionally, the correction device further comprises a urea injection amount determination module 6 used to determine the urea injection amount of the SCR device according to the corrected NOx value.

[0079] Optionally, the acquisition module is specifically used to acquire the urea injection amount of the engine and the current ammonia storage state.

[0080] Optionally, the correction condition of the original emission model NOx value comprises:

[0081] The urea injection amount of the engine is zero, and the urea injection amount is maintained for a second preset time;

[0082] The engine is currently in the ammonia storage state.

[0083] Optionally, the second preset time and the first preset time are the same time period.

[0084] Optionally, the correction coefficient determination module is specifically used to calculate the correction coefficient according to fac 修正 = NOx 传感器测量积分值 / NOx 模型积分值 ; wherein NOx 传感器测量积分值 is the first integral value, and NOx 模型积分值 is the second integral value.

[0085] Optionally, the correction module is specifically used to multiply fac 修正 to the calculated original emission model calibration map to correct the NOx value in the original emission model.

[0086] ​The embodiment of the present application also provides an engine comprising the original exhaust model NOx value correction device.

[0087] The embodiment of the present application also provides a vehicle comprising the engine.

[0088] The specific embodiment described above does not constitute a limitation on the protection scope of the present application. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method of correcting a raw emission model NOx value, characterized by, The application is suitable for an engine provided with a selective catalytic reduction (SCR) device, the SCR device comprising a downstream NOx sensor arranged downstream of an output end of the SCR device, and the correction method comprises: acquiring a current working state of the engine; determining whether a correction condition of a NOx value of an original emission model is met according to the current working state; if yes, acquiring a first integral value of a NOx value measured by the downstream NOx sensor within a first preset time and a second integral value of the NOx value in the original emission model within the first preset time; determining a correction coefficient according to a ratio of the first integral value to the second integral value; correcting the NOx value in the original emission model by substituting the correction coefficient into a calibration map of the original emission model; wherein the acquiring of the current working state of the engine comprises: acquiring a urea injection amount of the engine and a current ammonia storage state; the correction condition of the NOx value of the original emission model comprises: the urea injection amount of the engine is zero and lasts for a second preset time; the engine is currently in a non-ammonia storage state.

2. The method of correcting the raw model NOx value according to claim 1, characterized by, after the correction of the NOx value in the original emission model by substituting the correction coefficient into the calibration map of the original emission model, the method further comprises: determining a urea injection amount of the SCR device according to the corrected NOx value.

3. The method of correcting the raw model NOx value according to claim 1, characterized by, the second preset time is the same time period as the first preset time.

4. The method of correcting the raw model NOx value according to claim 1, characterized by, the determining of the correction coefficient according to the ratio of the first integral value to the second integral value comprises: According to fac 修正 = NOx 传感器测量积分值 / NOx 模型积分值 calculating the correction factor; wherein NOx 传感器测量积分值 is the first integral value, NOx 模型积分值 is the second integral value.

5. The method of correcting the raw model NOx value according to claim 4, characterized by, the correction of the NOx value in the original emission model by substituting the correction coefficient into the calibration map of the original emission model comprises: fac 修正 The fac is multiplied into the calculated original model calibration pulse spectrum to correct the NOx values in the original model.

6. An apparatus for correcting a raw emission model NOx value, characterized by, a correction device for performing the correction method of the NOx value of the original emission model according to any one of claims 1-5, the correction device comprising: an acquisition module for acquiring a current working state of the engine; a determination module for determining whether a correction condition of a NOx value of an original emission model is met according to the current working state; an integral module for acquiring a first integral value of a NOx value measured by the downstream NOx sensor within a first preset time and a second integral value of the NOx value in the original emission model within the first preset time when the determination module determines that the correction condition is met; a correction coefficient determination module for determining a correction coefficient according to a ratio of the first integral value to the second integral value; a correction module for correcting the NOx value in the original emission model by substituting the correction coefficient into a calibration map of the original emission model.

7. An engine characterized by, the correction device for correcting the NOx value of the original emission model according to claim 6 is used to perform the correction method of the NOx value of the original emission model according to any one of claims 1-5.

8. A vehicle characterized by comprising: the engine according to claim 7.

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