Online real-time compensation method for nitrogen-oxygen sensor

Abstract

The invention discloses an online real-time compensation method for a nitrogen-oxygen sensor, which comprises the following steps of: self-checking hardware, initializing an accumulation trigger, activating an algorithm, acquiring a real-time NOx conversion efficiency value and judging the reasonability of a numerical value, and performing accumulation assignment on a related accumulation trigger based on a judgment result of the conversion efficiency value. And judgment and compensation correction are performed based on the numerical value of the accumulative trigger, and the urea injection dosage is set after reference. According to the method, real-time compensation is additionally carried out or directly abandoned except for gas components and environmental impression factors by judging the rationality of the measured value of the nitrogen-oxygen sensor according to an algorithm on the basis of a NOx conversion efficiency value and an accumulative trigger value result, the aging degree of an individual NOx sensor is reflected, the accumulative error of the NOx measured value is prevented from being expanded, and the reliability of the system is improved. Not only is the workload of a post-processing system reduced, but also the measurement precision of the nitrogen-oxygen sensor is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle nitrogen and oxygen sensor measurement, and more particularly to an online real-time compensation method for a nitrogen and oxygen sensor. Background Art

[0002] Nitrogen oxide sensors are mainly used in the engine's selective catalytic reduction (SCR) after-treatment system. This system neutralizes NOx by injecting urea solution to control harmful gas emissions. Nitrogen oxide sensors are one of the most critical components of the diesel engine exhaust after-treatment SCR system.

[0003] A NOx sensor consists of three main components: the NOx probe, wiring harness, and NOx control unit. The NOx probe is the core physical unit for NOx measurement, converting NOx concentrations into current signals. The NOx control unit primarily performs electrochemical measurements on the NOx ceramic chip, collects and analyzes NOx signals, compensates for NOx, and then transmits the signals via the wiring harness to the aftertreatment system for analysis.

[0004] The measurement accuracy of nitrogen oxide sensors is affected by the measured gas composition (NH3 / NO2 / soot / silicone / biodiesel, etc.) and the environment (pressure / temperature). Although there are compensation algorithms for various factors, it is difficult to ensure high-precision test results under various complex environmental constraints. In particular, there are often certain deviations in the cumulative test results, which will cause the conversion efficiency of the post-treatment system to be affected to a certain extent.

[0005] When operating normally, the NOx sensor requires high measurement accuracy, which directly impacts the efficiency of the after-treatment system's emissions control. Large deviations in single-shot accuracy can lead to even greater cumulative deviations, resulting in incorrect urea concentration in the after-treatment system. Ultimately, this can reduce NOx conversion efficiency, lead to urea overflow, and cause frequent after-treatment system alarms.

[0006] Currently, there is no better solution for controlling the cumulative error of nitrogen oxide sensors. When the cumulative error causes reduced conversion efficiency or a urea solution overflow alarm, compensation is usually achieved by adjusting the urea injection volume, which increases the workload of the after-treatment system. Summary of the Invention

[0007] In view of the shortcomings of the prior art, the object of the present invention 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 object, the present invention provides the following technical solutions:

[0009] A method for online real-time compensation of nitrogen and oxygen sensors, the steps are as follows:

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

[0011] S2. Monitor and obtain the real-time NOx conversion efficiency value, and determine whether the real-time NOx conversion efficiency value is reasonable;

[0012] S3. Accumulate and assign values ​​to the cumulative trigger A and the cumulative trigger B according to the real-time NOx conversion efficiency value judgment result;

[0013] S4. Determine the numerical results of the current cumulative trigger A and the cumulative trigger B, and modify the NOx online real-time compensation factor according to the determination results;

[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 dosage based on the correction result.

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

[0016] Furthermore, 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.

[0017] Furthermore, when determining the real-time NOx conversion efficiency value in step S2, 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 cumulatively assigned a value, increasing 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 cumulatively assigned a value, increasing by 1 each time.

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

[0019] Furthermore, when judging the numerical results of the current cumulative trigger A and the cumulative trigger B in step S4, if the cumulative trigger A value is greater than the preset trigger threshold a, a 0.1% addition correction is performed on the NOx online real-time compensation factor; if the cumulative trigger B value is greater than the preset trigger threshold b, a 0.1% subtraction correction is performed on the NOx online real-time compensation factor.

[0020] Furthermore, when judging the numerical results of the current cumulative trigger A and the cumulative trigger B in step S4, 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.

[0021] Furthermore, in step S4 , after the addition correction is performed on the NOx online real-time compensation factor, the value of the cumulative trigger A is reduced by 1; after the subtraction correction is performed on the NOx online real-time compensation factor, the value of the cumulative trigger B is reduced by 1.

[0022] Furthermore, when determining the real-time NOx conversion efficiency value in step S2, 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 cumulatively assigned a value, increasing 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 cumulatively assigned a value, increasing by -1 each time;

[0023] In step S4, when determining the current cumulative trigger A and cumulative trigger B values, if the cumulative trigger A value is greater than the preset trigger threshold a, a 0.1% correction is applied to the NOx online real-time compensation factor; if the cumulative trigger B value is less than the preset trigger threshold b, a 0.1% correction is applied to the NOx online real-time compensation factor.

[0024] In step S4 , after the addition correction is performed on the NOx online real-time compensation factor, the value of the cumulative trigger A is reduced by 1; after the subtraction correction is performed on the NOx online real-time compensation factor, the value of the cumulative trigger B is increased by 1.

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

[0026] In summary, the present invention has the following beneficial effects: by judging whether the NOx conversion efficiency value is reasonable, corresponding cumulative assignment is performed on the cumulative trigger A and the cumulative trigger B, and the actual values ​​of the cumulative trigger A and the cumulative trigger B are further compared with the preset threshold value to judge whether the NOx online real-time compensation factor needs to be updated and how to correct the NOx online real-time compensation factor. Finally, the urea injection dose is adjusted based on the reference of the correction result, eliminating the adverse effects of the cumulative error of the nitrogen oxide sensor, not only ensuring high-precision test results, but also reducing the workload of the post-treatment system, and quantifying the degree of aging of the individual NOx sensors. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0028] Example 1:

[0029] The following is combined with Figure 1 The present invention is described in further detail.

[0030] A method for online real-time compensation of a nitrogen and oxygen sensor, comprising the following steps:

[0031] S1. Power on the NOx control system and complete the self-test of the nitrogen and oxygen sensors. If any abnormality is found, troubleshoot it immediately.

[0032] After the nitrogen oxide sensor passes the self-test, it enters the normal NOx measurement state, activates the NOx probe, and the electrochemical test system starts working to output the NOx sensor's measurement value, and then activates the algorithm;

[0033] In the preparation phase of the algorithm, the environment is initialized, 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;

[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 moment;

[0035] Entering the stage of quantifying the accumulated deviation of the real-time NOx measurement value, judging whether the real-time NOx conversion efficiency value is reasonable, the judgment standard is to compare the real-time NOx conversion efficiency value with the preset low conversion efficiency threshold and the preset high conversion efficiency threshold respectively;

[0036] If the real-time NOx conversion efficiency value is between a preset low conversion efficiency threshold and a preset high conversion efficiency threshold, the real-time NOx conversion efficiency value is determined to be reasonable;

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

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

[0039] S3. Accumulate and assign values ​​to the cumulative trigger A and the cumulative trigger B according to the real-time NOx conversion efficiency value judgment result;

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

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

[0043] Accumulation trigger A and accumulation trigger B actually represent the overflow and undercount of the real-time NOx conversion efficiency value, which are key factors for quantifying the accumulated deviation of NOx measurement values.

[0044] S4: Entering the NOx online real-time compensation factor calculation phase, determining the numerical results of the current cumulative trigger A and cumulative trigger B, and correcting the NOx online real-time compensation factor based on the determination results; when the cumulative triggers trigger their respective set thresholds, entering the NOx online real-time compensation factor correction phase, and performing fixed-step adjustment 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;

[0045] If the accumulated trigger A value is greater than the preset trigger threshold a, the NOx measurement value is too large, and a 0.1% correction is applied to the NOx online real-time compensation factor;

[0046] If the accumulated trigger B value is greater than the preset trigger threshold b, the NOx measurement value is too small and a 0.1% deduction correction is made to the NOx online real-time compensation factor;

[0047] 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 remains 1;

[0048] After the addition correction is performed for the NOx online real-time compensation factor, the value of the cumulative trigger A is reduced by 1; after the deduction correction is performed for the NOx online real-time compensation factor, the value of the cumulative trigger B is reduced by 1; it does not affect the subsequent compensation measurement;

[0049] S5. Update the NOx online real-time compensation factor to the correction calculation of the sensor measurement value system, perform weighted coefficient correction on the NOx sensor measurement value, and set the urea injection dosage with reference to the corrected NOx sensor measurement value.

[0050] The algorithm, based on the aftertreatment system, proposes a key compensation factor for NOx sensor measurements based on the real-time NOx conversion efficiency, known as the NOx online real-time compensation factor. This compensation factor monitors and tracks the aging of individual NOx sensors in real time and quantifies this aging. This ensures that accumulated deviations over the entire NOx sensor lifecycle are effectively controlled, resulting in more efficient and accurate engine aftertreatment systems. The preset conversion efficiency thresholds, trigger thresholds a and b, and the NOx online real-time compensation factor can take any value, positive or negative, depending on system requirements. The algorithm can operate in real time or periodically.

[0051] Example 2:

[0052] The following is combined with Figure 1 The present invention is described in further detail.

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

[0054] S1. Power on the NOx control system and complete the self-test of the nitrogen and oxygen sensors. If any abnormality is found, troubleshoot it immediately.

[0055] After the nitrogen oxide sensor passes the self-test, it enters the normal NOx measurement state, activates the NOx probe, and the electrochemical test system starts working to output the NOx sensor's measurement value, and then activates the algorithm;

[0056] In the preparation phase of the algorithm, the environment is initialized, 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. Monitor the real-time NOx conversion efficiency value in the SCR system and obtain the real-time NOx conversion efficiency value at the current moment;

[0058] Entering the stage of quantifying the accumulated deviation of the real-time NOx measurement value, judging whether the real-time NOx conversion efficiency value is reasonable, the judgment standard is to compare the real-time NOx conversion efficiency value with the preset low conversion efficiency threshold and the preset high conversion efficiency threshold respectively;

[0059] If the real-time NOx conversion efficiency value is between a preset low conversion efficiency threshold and a preset high conversion efficiency threshold, the real-time NOx conversion efficiency value is determined to be reasonable;

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

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

[0062] S3. Accumulate and assign values ​​to the cumulative trigger A and the cumulative trigger B according to the real-time NOx conversion efficiency value judgment result;

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

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

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

[0066] Accumulation trigger A and accumulation trigger B actually represent the overflow and undercount of the real-time NOx conversion efficiency value, which are key factors for quantifying the accumulated deviation of NOx measurement values.

[0067] S4: Entering the NOx online real-time compensation factor calculation phase, determining the numerical results of the current cumulative trigger A and cumulative trigger B, and correcting the NOx online real-time compensation factor based on the determination results; when the cumulative triggers trigger their respective set thresholds, entering the NOx online real-time compensation factor correction phase, and performing fixed-step adjustment 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 accumulated trigger A value is greater than the preset trigger threshold a, the NOx measurement value is too large, and a 0.1% correction is applied to the NOx online real-time compensation factor;

[0069] If the accumulated trigger B value is less than the preset trigger threshold b, the NOx measurement value is too small and a 0.1% deduction correction is made to the NOx online real-time compensation factor;

[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 remains 1;

[0071] After the addition correction is performed for the NOx online real-time compensation factor, the value of the cumulative trigger A decreases by 1; after the deduction correction is performed for the NOx online real-time compensation factor, the value of the cumulative trigger B increases by 1; it does not affect the subsequent compensation measurement;

[0072] S5. Update the NOx online real-time compensation factor to the correction calculation of the sensor measurement value system, perform weighted coefficient correction on the NOx sensor measurement value, and set the urea injection dosage with reference to the corrected NOx sensor measurement value.

[0073] It should be noted that this specific embodiment is merely an explanation of the present invention and is not a limitation of the present invention. After reading this specification, those skilled in the art may make non-creative modifications to this embodiment as needed, but as long as they are within the scope of the claims of the present invention, they are protected by patent law.

Claims

1. A method for online real-time compensation of nitrogen and oxygen sensors, characterized by: Here are the steps: S1, nitrogen oxide sensor self-test, activate NOx probe, transmit measurement value, activate algorithm, and initialize cumulative trigger A and cumulative trigger B; S2. Monitor and obtain the real-time NOx conversion efficiency value, and determine whether the real-time NOx conversion efficiency value is reasonable; S3. Accumulate and assign values ​​to the cumulative trigger A and the cumulative trigger B according to the real-time NOx conversion efficiency value judgment result; S4. Determine the numerical results of the current cumulative trigger A and the cumulative trigger B, and modify the NOx online real-time compensation factor according to the determination results; S5. Update the NOx online real-time compensation factor to the correction calculation of the sensor measurement value system, and set the urea injection dosage based on the correction result.

2. The online real-time compensation method for nitrogen oxide sensors according to claim 1, characterized in that: In step S1 , the accumulation trigger A and the accumulation trigger B are both set to an initial value of 0, and the initial value of the NOx online real-time compensation factor is set to 1.

3. The online real-time compensation method for nitrogen oxide sensors according to claim 1, characterized in that: 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 online real-time compensation method for nitrogen oxide sensors according to claim 1, characterized in that: When judging the real-time NOx conversion efficiency value in step S2, 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 cumulatively assigned a value, increasing 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 cumulatively assigned a value, increasing by 1 each time.

5. The online real-time compensation method for nitrogen oxide sensors according to claim 1, characterized in that: When determining the real-time NOx conversion efficiency value in step S2, if the real-time NOx conversion efficiency value is between the preset low conversion efficiency threshold and the preset high conversion efficiency threshold, no accumulation trigger is triggered in step S3.

6. The online real-time compensation method for nitrogen oxide sensors according to claim 1, characterized in that: In step S4, when judging the numerical results of the current cumulative trigger A and the cumulative trigger B, if the cumulative trigger A value is greater than the preset trigger threshold a, a 0.1% correction is applied to the NOx online real-time compensation factor; If the accumulated trigger B value is greater than the preset trigger threshold b, a 0.1% deduction correction is performed on the NOx online real-time compensation factor.

7. The online real-time compensation method for nitrogen oxide sensors according to claim 1, characterized in that: When judging the numerical results of the current cumulative trigger A and the cumulative trigger B in step S4, 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 remains 1.

8. The online real-time compensation method for nitrogen oxide sensors according to claim 1, characterized in that: After the NOx online real-time compensation factor is added and corrected in step S4, 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 is reduced by 1.

9. The online real-time compensation method for nitrogen oxide sensors according to claim 1, characterized in that: When determining the real-time NOx conversion efficiency value in step S2, 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 cumulatively assigned a value, increasing 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 cumulatively assigned a value, increasing by -1 each time; In step S4, when judging the numerical results of the current cumulative trigger A and the cumulative trigger B, if the cumulative trigger A value is greater than the preset trigger threshold a, a 0.1% correction is applied to the NOx online real-time compensation factor; If the cumulative trigger B value is less than the preset trigger threshold b, a 0.1% deduction correction is made to the NOx online real-time compensation factor; After the NOx online real-time compensation factor is added and corrected in step S4, 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 increases by 1.

10. The online real-time compensation method for nitrogen oxide sensors according to claim 1, characterized in that: The NOx online real-time compensation factor updated in step S5 is directly multiplied by the coefficient on the NOx sensor measurement value, and the calculated NOx concentration is used as a reference for adjusting the subsequent urea injection dosage.

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