A method for online real-time compensation of a nitrogen-oxygen sensor

Abstract

The application discloses a kind of nitrogen oxygen sensor online real-time compensation methods, steps include hardware self-checking, cumulative trigger initialization, algorithm activation, obtain real-time NOx conversion efficiency value and judge value rationality, based on the judgment result of conversion efficiency value to relevant cumulative trigger cumulative assignment, based on the value of cumulative trigger is judged and compensation correction, reference after setting urea injection dose.The application is measured by nitrogen oxygen sensor according to algorithm, based on the rationality of NOx conversion efficiency value and cumulative trigger value result judgment, in addition to gas component and environmental impression factor, additional or directly abandon real-time compensation, reflect the aging degree of NOx sensor individual, avoid NOx measurement cumulative error expansion, not only reduce the work burden of aftertreatment system, also improve the measurement accuracy of nitrogen oxygen sensor.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of nitrogen oxide sensor measurement for vehicles, and more particularly, to an online real-time compensation method for a nitrogen oxide sensor. BACKGROUND

[0002] The nitrogen oxide sensor is mainly applied to an engine selective catalytic reduction (SCR) aftertreatment system, which neutralizes NOx by spraying urea solution to achieve the purpose of controlling harmful gas emissions. The nitrogen oxide sensor is one of the most critical components of the diesel engine exhaust aftertreatment SCR system.

[0003] The nitrogen oxide sensor mainly consists of three parts, including a nitrogen oxide probe, a wire harness, and a nitrogen oxide control unit. The nitrogen oxide probe is the core physical unit for NOx measurement, responsible for converting the NOx concentration value into a current signal. The nitrogen oxide control unit is mainly responsible for electrochemical measurement of the nitrogen oxide ceramic chip, collecting and analyzing the NOx signal, compensating for NOx, and then sending it to the aftertreatment system for analysis through the wire harness.

[0004] The measurement accuracy of the nitrogen oxide sensor is affected by the measured gas components (NH3 / NO2 / soot / silicone / biodiesel, etc.) and the environment (pressure / temperature). Although there are compensation algorithms for various factors, it is difficult to guarantee high-precision test results under various complex environmental constraints, especially the cumulative test results often have certain deviations, which can affect the conversion efficiency of the aftertreatment system to some extent.

[0005] The nitrogen oxide sensor requires high measurement accuracy when working normally, and the measurement accuracy directly affects the efficiency of the aftertreatment system emission control. If the single measurement accuracy deviation is large, the cumulative measurement accuracy deviation will be larger, resulting in incorrect urea solution in the aftertreatment system, and finally reducing the NOx conversion efficiency or causing urea solution overflow, and frequent alarm of the aftertreatment system.

[0006] Currently, there is no good solution to control the cumulative error of the nitrogen oxide sensor. When the conversion efficiency is reduced or the urea solution overflows and alarms, the urea injection amount is usually adjusted to compensate, which increases the workload of the aftertreatment system. SUMMARY

[0007] In view of the deficiencies in the prior art, the purpose of the present application is to provide an online real-time compensation method for a nitrogen oxide sensor to solve one or more of the above problems.

[0008] To achieve the above purpose, the present application provides the following technical solutions:

[0009] An online real-time compensation method for a nitrogen oxide sensor, the steps are as follows:

[0010] S1, nitrogen oxide sensor self-check, activate NOx probe, transmit measurement value, activate algorithm, initialize cumulative trigger A and cumulative trigger B;

[0011] S2, monitor and obtain real-time NOx conversion efficiency value, judge whether the real-time NOx conversion efficiency value is reasonable;

[0012] S3, according to the judgment result of the real-time NOx conversion efficiency value, cumulative trigger A and cumulative trigger B are added;

[0013] S4, judge the numerical result of the current cumulative trigger A and cumulative trigger B, and correct the NOx online real-time compensation factor according to the judgment result;

[0014] S5, update the NOx online real-time compensation factor to the correction calculation of the sensor measurement value system, and set the urea injection dose according to the correction result.

[0015] Further, in step S1, cumulative trigger A and cumulative trigger B are both set to initial value 0, and the initial value of the NOx online real-time compensation factor is set to 1.

[0016] Further, in step S2, the real-time NOx conversion efficiency value in the SCR system is monitored, and the NOx conversion efficiency value at the current time is obtained.

[0017] Further, in step S2, when judging the real-time NOx conversion efficiency value, if the real-time NOx conversion efficiency value is greater than the preset conversion efficiency high threshold, in step S3, cumulative trigger A is added by 1 each time; if the real-time NOx conversion efficiency value is less than the preset conversion efficiency low threshold, in step S3, cumulative trigger B is added by 1 each time.

[0018] Further, in step S2, when judging the real-time NOx conversion efficiency value, if the real-time NOx conversion efficiency value is between the preset conversion efficiency low threshold and the preset conversion efficiency high threshold, in step S3, no cumulative trigger is triggered.

[0019] Further, in step S4, when judging the numerical result of the current cumulative trigger A and cumulative trigger B, if the value of cumulative trigger A is greater than the preset trigger threshold a, the NOx online real-time compensation factor is added by 0.1%; if the value of cumulative trigger B is greater than the preset trigger threshold b, the NOx online real-time compensation factor is subtracted by 0.1%.

[0020] Further, in step S4, when judging the numerical result of the current cumulative trigger A and cumulative trigger B, if the value of cumulative trigger A is less than or equal to the preset trigger threshold a and the value of cumulative trigger B is less than or equal to the preset trigger threshold b, the NOx online real-time compensation factor is still 1.

[0021] Further, after the NOx online real-time compensation factor is added in step S4, the value of the cumulative trigger A is reduced by 1; after the NOx online real-time compensation factor is subtracted, the value of the cumulative trigger B is reduced by 1.

[0022] Further, when the real-time NOx conversion efficiency value is greater than the preset conversion efficiency high threshold in step S2, the cumulative trigger A is added by 1 in step S3; when the real-time NOx conversion efficiency value is less than the preset conversion efficiency low threshold, the cumulative trigger B is added by -1 in step S3.

[0023] When the value of the cumulative trigger A is greater than the preset trigger threshold a in step S4, the NOx online real-time compensation factor is added by 0.1%; when the value of the cumulative trigger B is less than the preset trigger threshold b, the NOx online real-time compensation factor is subtracted by 0.1%.

[0024] After the NOx online real-time compensation factor is added in step S4, the value of the cumulative trigger A is reduced by 1; after the NOx online real-time compensation factor is subtracted, the value of the cumulative trigger B is increased by 1.

[0025] Further, the NOx online real-time compensation factor updated in step S5 is directly multiplied by the NOx sensor measurement value, and the calculated NOx concentration is used as a reference for subsequent urea injection dose adjustment.

[0026] In summary, the present application has the following beneficial effects: by judging whether the NOx conversion efficiency value is reasonable, the cumulative trigger A and the cumulative trigger B are added by corresponding values, and further, by comparing the actual values of the cumulative trigger A and the cumulative trigger B with the preset threshold, it is determined whether the NOx online real-time compensation factor needs to be updated and how to correct the NOx online real-time compensation factor, and finally, the urea injection dose is adjusted according to the correction result, which eliminates the adverse effects of the cumulative error of the nitrogen oxide sensor, not only ensures high-precision test results, but also reduces the working load of the aftertreatment system, and quantifies the aging degree of the NOx sensor. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 The flowchart of an embodiment of the present application is provided. DETAILED DESCRIPTION

[0028] Example 1:

[0029] The following will be described in detail with reference to the accompanying drawings. Figure 1 The present application will be further described in detail.

[0030] A nitrogen oxide sensor online real-time compensation method, the steps comprising:

[0031] S1, the NOx control system is powered on, and the nitrogen oxide sensor self-check is completed. If there is an abnormality, the fault is timely excluded;

[0032] After the nitrogen oxide sensor self-check is passed, enter the normal NOx measurement state, activate the NOx probe, and the electrochemical test system starts to work to output the measurement value of the NOx sensor, and then activate the algorithm;

[0033] The preparation stage of the algorithm, initialize the environment, set the cumulative trigger A and the cumulative trigger B to 0, and set the NOx online real-time compensation factor to 1;

[0034] S2, monitor the real-time NOx conversion efficiency value in the SCR system, and obtain the real-time NOx conversion efficiency value at the current time;

[0035] Enter the real-time NOx measurement value accumulation deviation quantification stage, judge whether the real-time NOx conversion efficiency value is reasonable, and the judgment standard is to compare the real-time NOx conversion efficiency value with the preset conversion efficiency low threshold and the preset conversion efficiency high threshold respectively;

[0036] If the real-time NOx conversion efficiency value is between the preset conversion efficiency low threshold and the preset conversion efficiency high threshold, it is judged that the real-time NOx conversion efficiency value is reasonable;

[0037] If the real-time NOx conversion efficiency value is greater than the preset conversion efficiency high threshold, it is judged that the real-time NOx conversion efficiency value is unreasonable and high;

[0038] If the real-time NOx conversion efficiency value is less than the preset conversion efficiency low threshold, it is judged that the real-time NOx conversion efficiency value is unreasonable and low;

[0039] S3, according to the judgment result of the real-time NOx conversion efficiency value, the cumulative trigger A and the cumulative trigger B are added;

[0040] If the judgment result is that the real-time NOx conversion efficiency value is reasonable, the cumulative trigger A and the cumulative trigger B are not triggered;

[0041] If the judgment result is that the real-time NOx conversion efficiency value is unreasonable and high, the cumulative trigger A is added by 1 each time;

[0042] If the judgment result is that the real-time NOx conversion efficiency value is unreasonable and low, the cumulative trigger B is added by 1 each time;

[0043] The cumulative trigger A and the cumulative trigger B actually represent the overflow times and the insufficient times of the real-time NOx conversion efficiency value, which is the key factor of the NOx measurement value accumulation deviation quantification;

[0044] S4, entering the NOx online real-time compensation factor calculation stage, judging the numerical results of the cumulative trigger A and the cumulative trigger B, and correcting the NOx online real-time compensation factor according to the judgment result; when the cumulative triggers trigger the respective set thresholds, entering the NOx online real-time compensation factor correction link, and performing step length adjustment on the NOx online real-time compensation factor, wherein the NOx online real-time compensation factor is a cumulative compensation coefficient of the NOx sensor measurement value;

[0045] If the cumulative trigger A value > preset trigger threshold a, the NOx measurement value is too large, and the NOx online real-time compensation factor is added by 0.1%;

[0046] If the cumulative trigger B value > preset trigger threshold b, the NOx measurement value is too small, and the NOx online real-time compensation factor is deducted by 0.1%;

[0047] If the cumulative trigger A value ≤ preset trigger threshold a and the cumulative trigger B value ≤ preset trigger threshold b, the NOx online real-time compensation factor is still 1;

[0048] After the NOx online real-time compensation factor is added, the value of the cumulative trigger A is reduced by 1; after the NOx online real-time compensation factor is deducted, the value of the cumulative trigger B is reduced by 1; and the subsequent compensation measurement is not affected.

[0049] S5, updating the NOx online real-time compensation factor to the correction calculation of the sensor measurement value system, performing weighting coefficient correction on the NOx sensor measurement value, and setting the urea injection dose with reference to the corrected NOx sensor measurement value.

[0050] The whole algorithm starts from the post-processing system, proposes a key compensation factor of the NOx sensor measurement value, that is, the NOx online real-time compensation factor, based on the NOx real-time conversion efficiency value. The compensation factor can monitor and track the aging degree of the individual NOx sensor in real time, and quantize this situation. The cumulative deviation of the NOx sensor in the whole life cycle is effectively controlled, so that the engine post-processing system works more efficiently and accurately. The preset conversion efficiency high and low threshold, the preset trigger threshold a and b, and the value of the NOx online real-time compensation factor have no limit, and can be positive or negative, which is specifically set according to the system needs. The algorithm can be real-time or periodic compensation.

[0051] Example 2:

[0052] The following will be combined with the accompanying Figure 1 The application is further described in detail.

[0053] A nitrogen oxygen sensor online real-time compensation method, comprising the following steps:

[0054] S1, the NOx control system is powered on, the nitrogen oxygen sensor self-check is completed, and if there is an abnormality, the fault is timely eliminated;

[0055] After the nitrogen oxygen sensor self-check is passed, the normal NOx measurement state is entered, the NOx probe is activated, the electrochemical test system starts to work to output the measurement value of the NOx sensor, and then the algorithm is activated;

[0056] In the preparation stage of the algorithm, the initialization environment is performed, the cumulative trigger A and the cumulative trigger B are both set to 0, and the NOx online real-time compensation factor is set to 1;

[0057] S2, the real-time NOx conversion efficiency value in the SCR system is monitored, and the real-time NOx conversion efficiency value at the current time is obtained;

[0058] The real-time NOx measurement value accumulation deviation quantification stage is entered, and whether the real-time NOx conversion efficiency value is reasonable is judged, and the judgment standard is that the real-time NOx conversion efficiency value is compared with the preset conversion efficiency low threshold value and the preset conversion efficiency high threshold value respectively;

[0059] If the real-time NOx conversion efficiency value is between the preset conversion efficiency low threshold value and the preset conversion efficiency high threshold value, it is judged that the real-time NOx conversion efficiency value is reasonable;

[0060] If the real-time NOx conversion efficiency value is greater than the preset conversion efficiency high threshold value, it is judged that the real-time NOx conversion efficiency value is unreasonable and is too high;

[0061] If the real-time NOx conversion efficiency value is less than the preset conversion efficiency low threshold value, it is judged that the real-time NOx conversion efficiency value is unreasonable and is too low;

[0062] S3, according to the judgment result of the real-time NOx conversion efficiency value, the cumulative trigger A and the cumulative trigger B are added and assigned values;

[0063] If the judgment result is that the real-time NOx conversion efficiency value is reasonable, the cumulative trigger A and the cumulative trigger B are not triggered;

[0064] If the judgment result is that the real-time NOx conversion efficiency value is unreasonable and is too high, the cumulative trigger A is added and assigned a value, and is increased by 1 each time;

[0065] If the judgment result is that the real-time NOx conversion efficiency value is unreasonable and is too low, the cumulative trigger B is added and assigned a value, and is decreased by 1 each time;

[0066] The cumulative trigger A and the cumulative trigger B actually represent the overflow times and the insufficient times of the real-time NOx conversion efficiency value, which is a key factor of the NOx measurement value accumulation deviation quantification;

[0067] S4, entering the NOx online real-time compensation factor calculation stage, judging the numerical results of the cumulative trigger A and the cumulative trigger B, and correcting the NOx online real-time compensation factor according to the judgment result; when the cumulative trigger triggers the respective set threshold, entering the NOx online real-time compensation factor correction link, and step length adjustment can be performed on the NOx online real-time compensation factor, wherein the NOx online real-time compensation factor is the cumulative compensation coefficient of the NOx sensor measurement value;

[0068] If the cumulative trigger A value is greater than the preset trigger threshold a, the NOx measurement value is too large, and the NOx online real-time compensation factor is added by 0.1% correction;

[0069] If the cumulative trigger B value is less than the preset trigger threshold b, the NOx measurement value is too small, and the NOx online real-time compensation factor is subtracted by 0.1% correction;

[0070] If the cumulative trigger A value is less than or equal to the preset trigger threshold a and the cumulative trigger B value is less than or equal to the preset trigger threshold b, the NOx online real-time compensation factor is still 1;

[0071] After the NOx online real-time compensation factor is added by correction, the cumulative trigger A value is reduced by 1; after the NOx online real-time compensation factor is subtracted by correction, the cumulative trigger B value is increased by 1; and the subsequent compensation measurement is not affected.

[0072] S5, updating the NOx online real-time compensation factor to the correction calculation of the sensor measurement value system, correcting the NOx sensor measurement value by a weighting coefficient, and setting the urea injection dose with reference to the corrected NOx sensor measurement value.

[0073] It should be noted that the specific embodiments are merely an explanation of the present application, and are not a limitation of the present application. Those skilled in the art can make modifications to the embodiments without creative contribution after reading the specification, as long as the modifications are within the scope of the claims of the present application.

Claims

1. A method for online real-time compensation of a nitrogen-oxygen sensor, characterized in that: The steps are as follows: S1. Nitrogen oxygen sensor self-test, activate NOx probe, transmit measurement value, activate algorithm, and initialize cumulative trigger A and cumulative trigger B; S2. Monitor and obtain real-time NOx conversion efficiency values, and determine whether the real-time NOx conversion efficiency values ​​are reasonable; S3. Based on the real-time NOx conversion efficiency value, the result is used to accumulate and assign values ​​to accumulator trigger A and accumulator trigger B. S4. Determine the numerical results of the current cumulative trigger A and cumulative trigger B, and correct the NOx online real-time compensation factor based on the determination result; S5. Update the NOx online real-time compensation factor into the correction calculation of the sensor measurement system, and set the urea injection dose with reference to the correction result.

2. The online real-time compensation method of a NOx sensor according to claim 1, characterized by: In step S1, both cumulative trigger A and cumulative trigger B are set to an initial value of 0, and the NOx online real-time compensation factor is set to an initial value of 1.

3. The method of claim 1, wherein: In step S2, the real-time NOx conversion efficiency value in the SCR system is monitored, and the NOx conversion efficiency value at the current moment is obtained.

4. The method of claim 1, wherein: In step S2, when determining the real-time NOx conversion efficiency value, if the real-time NOx conversion efficiency value is greater than the preset high conversion efficiency threshold, then in step S3, the cumulative trigger A is incremented by 1 each time; if the real-time NOx conversion efficiency value is less than the preset low conversion efficiency threshold, then in step S3, the cumulative trigger B is incremented by 1 each time.

5. The method of claim 1, wherein: In step S2, when determining the real-time NOx conversion efficiency value, if the real-time NOx conversion efficiency value is between the preset low conversion efficiency threshold and the preset high conversion efficiency threshold, then no cumulative trigger is triggered in step S3.

6. The method of online real-time compensation for a NOx sensor of claim 1, wherein: In step S4, when judging the numerical results of the current cumulative trigger A and cumulative trigger B, if the value of cumulative trigger A is greater than the preset trigger threshold a, then the NOx online real-time compensation factor is adjusted by 0.1%. If the cumulative trigger value B is greater than the preset trigger threshold b, then a 0.1% deduction correction will be applied to the NOx online real-time compensation factor.

7. The method of claim 1, wherein: In step S4, when judging the numerical results of the current cumulative trigger A and cumulative trigger B, if the value of cumulative trigger A is less than or equal to the preset trigger threshold a and the value of cumulative trigger B is less than or equal to the preset trigger threshold b, then the NOx online real-time compensation factor remains 1.

8. The method of claim 1, wherein: In step S4, after the NOx online real-time compensation factor is added and corrected, the value of the cumulative trigger A is reduced by 1; After deducting and correcting the NOx online real-time compensation factor, the cumulative trigger B value decreases by 1.

9. The method of claim 1, wherein: In step S2, when determining the real-time NOx conversion efficiency value, if the real-time NOx conversion efficiency value is greater than the preset high conversion efficiency threshold, then in step S3, the cumulative trigger A is incremented by 1 each time; if the real-time NOx conversion efficiency value is less than the preset low conversion efficiency threshold, then in step S3, the cumulative trigger B is incremented by -1 each time. In step S4, when judging the numerical results of the current cumulative trigger A and cumulative trigger B, if the value of cumulative trigger A is greater than the preset trigger threshold a, then the NOx online real-time compensation factor is adjusted by 0.1%. If the cumulative trigger value B is less than the preset trigger threshold b, then a 0.1% deduction correction will be applied to the NOx online real-time compensation factor. The value of the cumulative trigger A is reduced by 1 after the addition correction of the NOx online real-time compensation factor in step S4; The value of the cumulative trigger B is increased by 1 after the subtraction correction of the NOx online real-time compensation factor.

10. The method of online real-time compensation of a NOx sensor of claim 1, wherein: The updated NOx online real-time compensation factor in step S5 is directly multiplied with the measured value of the NOx sensor, and the calculated NOx concentration is used as a reference for the subsequent adjustment of the urea injection dose.

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