CN114324474B - Sensitivity correction method for nitrogen-oxygen sensor - Google Patents
Sensitivity correction method for nitrogen-oxygen sensor Download PDFInfo
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- CN114324474B CN114324474B CN202111549103.XA CN202111549103A CN114324474B CN 114324474 B CN114324474 B CN 114324474B CN 202111549103 A CN202111549103 A CN 202111549103A CN 114324474 B CN114324474 B CN 114324474B
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- 238000000034 method Methods 0.000 title claims abstract description 34
- 230000035945 sensitivity Effects 0.000 title claims abstract description 29
- 238000012937 correction Methods 0.000 title claims abstract description 15
- DOTMOQHOJINYBL-UHFFFAOYSA-N molecular nitrogen;molecular oxygen Chemical compound N#N.O=O DOTMOQHOJINYBL-UHFFFAOYSA-N 0.000 title claims abstract description 13
- 239000007789 gas Substances 0.000 claims abstract description 26
- 238000009792 diffusion process Methods 0.000 claims abstract description 17
- 230000007246 mechanism Effects 0.000 claims abstract description 10
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 36
- 239000001301 oxygen Substances 0.000 claims description 36
- 229910052760 oxygen Inorganic materials 0.000 claims description 36
- -1 CO 2 Inorganic materials 0.000 claims description 2
- 230000008569 process Effects 0.000 abstract description 9
- 238000001514 detection method Methods 0.000 abstract description 6
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 23
- 238000005259 measurement Methods 0.000 description 7
- 238000010586 diagram Methods 0.000 description 4
- AVXURJPOCDRRFD-UHFFFAOYSA-N Hydroxylamine Chemical class ON AVXURJPOCDRRFD-UHFFFAOYSA-N 0.000 description 3
- 230000008859 change Effects 0.000 description 3
- 238000009825 accumulation Methods 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 230000007774 longterm Effects 0.000 description 2
- 238000012423 maintenance Methods 0.000 description 2
- 238000005086 pumping Methods 0.000 description 2
- 238000003916 acid precipitation Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 239000000428 dust Substances 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- XTQHKBHJIVJGKJ-UHFFFAOYSA-N sulfur monoxide Chemical class S=O XTQHKBHJIVJGKJ-UHFFFAOYSA-N 0.000 description 1
- 229910052815 sulfur oxide Inorganic materials 0.000 description 1
- 239000002341 toxic gas Substances 0.000 description 1
- 231100000925 very toxic Toxicity 0.000 description 1
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- Investigating Or Analyzing Materials By The Use Of Fluid Adsorption Or Reactions (AREA)
- Measuring Oxygen Concentration In Cells (AREA)
Abstract
The invention relates to the field of automobile electronic sensing detection, in particular to a sensitivity correction method for a nitrogen-oxygen sensor. The correction method is based on a gas diffusion mechanism, determines the relation among pump current, temperature and gas concentration to be detected, performs online recalibration of sensitivity by a temperature disturbance method, recalibrates K by the temperature disturbance method, and realizes correction of sensor sensitivity. The method is simple and reliable, and can effectively improve the detection precision in the use process of the sensor.
Description
Technical Field
The invention relates to a correction method, in particular to a sensitivity correction method for a nitrogen-oxygen sensor.
Background
In recent years, with the continuous development of economy and the improvement of the living standard of people, the maintenance amount of Chinese automobiles is continuously increased, the increase is kept above 10 percent, and by the year 2020, the maintenance amount of Chinese automobiles is broken through by 3.72 hundred million. Exhaust pollution from automobile exhaust is a main source of atmospheric pollution and accounts for more than six of the atmospheric pollution components. Among them, nitrogen oxides mainly composed of NO and NO2 are brown and have a pungent odor, and although the content of nitrogen oxides in automobile exhaust is not very high, the nitrogen oxides are very toxic, which is about 3 times of sulfur oxides, and are one of the important causes of formation of photochemical smog and acid rain. Along with the export of the latest emission standards of China, no. five and No. four and Europe, the traditional vehicular oxygen sensor can only complete the oxygen measurement function required by the standard, but can not complete the detection requirement of nitrogen oxides in the exhaust gas. The detection sensor of nitrogen oxides is blocked by the technology of foreign large companies for a long time. Therefore, the autonomous development of the nitrogen-oxygen sensor for detecting the concentration of nitrogen oxides in the automobile exhaust is urgently needed in China, the combustion performance of the engine can be improved, and the emission of harmful gases is greatly reduced.
Besides a large amount of toxic gases, the automobile exhaust contains a large amount of suspended matters and particulate matters and dust, and in the long-term use process of the nitrogen-oxygen sensor, a diffusion channel can be blocked due to accumulation of the particulate matters, so that the diffusion of the gases is affected, and further, the measurement sensitivity is reduced. Therefore, in order to improve the detection accuracy of the sensor, it is necessary to correct the sensitivity thereof.
Disclosure of Invention
The invention aims to solve the defects and provide a sensitivity correction method of a nitrogen-oxygen sensor.
In order to overcome the defects in the background art, the technical scheme adopted by the invention for solving the technical problems is as follows: the sensitivity correction method of the nitrogen-oxygen sensor is based on a gas diffusion mechanism, determines the relation among pump current, temperature and concentration of gas to be measured, and performs online recalibration of sensitivity by a temperature disturbance method.
According to another embodiment of the present invention, the oxygen diffusion mechanism is:。
according to another embodiment of the present invention, the specific steps of the sensitivity correction method are as follows:
s1, at a certain fixed oxygen concentrationUnder, the sensor temperature is set to +.>、/>Pump current of the measuring sensor at these two temperatures +.>、/>The relationship between pump current and oxygen concentration obtained by a gas diffusion mechanism is as follows: />，；
S2, calculating according to the pump currents at two temperatures，
；
S3, according to the working temperature of the sensor、/>And measuring the oxygen concentration in the gas>Calculating sensitivity->The value of the sum of the values,；
s4, obtaining sensitivity according to the S3Values, to determine corrected sensor pump current versus oxygen concentration,。
according to another embodiment of the present invention, the method further comprises that the gas to be measured is oxygen, CO 2 ，NOx。
The beneficial effects of the invention are as follows: the sensitivity correction method of the nitrogen-oxygen sensor can solve the measurement errors caused by factors such as gas diffusion channel blockage and the like in the long-term working process of the sensor, and improves the steady-state measurement accuracy of the nitrogen-oxygen sensor.
Drawings
The invention will be further described with reference to the drawings and examples.
FIG. 1 is a schematic diagram of the internal structure of a nitrogen-oxygen sensor used in the present invention;
FIG. 2 is a schematic diagram of the sensitivity calibration of the nitroxide sensor of the present invention;
FIG. 3 is a flow chart of the sensitivity calibration of the nitroxide sensor of the present invention.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments of the present invention. Embodiments of the invention are described herein in terms of various specific embodiments, including those that are apparent to those of ordinary skill in the art and all that come within the scope of the invention.
According to the gas diffusion mechanism, the pump current and the concentration of the gas to be detected are in a linear relation, and the slope, namely the sensitivity, is marked as K. During the use process of the sensor, the diffusion channel is blocked due to the accumulation of particulate matters, so that the diffusion of gas is influenced, the sensitivity K is changed, and the measurement sensitivity is reduced. Therefore, K is recalibrated by a temperature disturbance method, and the sensor sensitivity is corrected. The method is simple and reliable, and can effectively improve the detection precision in the use process of the sensor.
Internal structure diagram of nitrogen-oxygen sensor as shown in FIG. 1, V 0 、V 1 And V 2 For three Nernst voltages, V p0 、V p1 And V p2 The pump voltage is respectively the pump voltage of the main pump, the auxiliary pump and the measuring pump, and is used for pumping oxygen in the pumping air cavity, a large amount of oxygen is pumped out in the main pump, a small amount of residual oxygen is pumped out in the auxiliary pump, and oxygen generated by nitric oxide decomposition is pumped out in the measuring pump. By establishing main, auxiliary, measuring the current I generated by the pump p0 、I p1 And I p2 The relation curve with the concentration of oxygen and nitrogen oxides can be used for measuring the concentration of the corresponding gas in the tail gas by measuring the magnitude of the current, namely, the pump current and the concentration of the gas to be measured show a certain linear relation, and oxygen is taken as an example.
By gas diffusion mechanism:
；
wherein, K is determined by the structure and volume of the diffusion channel and the gas components, when the diffusion channel is blocked by the particulate matters, the K value is changed, namely:
；
this will cause the measured pump current to change at the same oxygen concentration, althoughAnd->There is still a good linear relation but the linear slope at this time is +.>The set point of (2) has been different, i.e. the sensor oxygen sensitivity has changed, resulting in a deviation of the measured value of the oxygen concentration. Measurement value->And the true value->The relation between the two is:
；
a schematic diagram of the sensitivity correction of the nitroxide sensor is shown in fig. 2. Because the K value is changed due to the blockage of the particles in the use process of the sensor, the change process is not affected by the temperature, namely the actual change isTherefore, the sensitivity can be recalibrated on line by adopting a temperature disturbance method under the atmosphere condition with known oxygen concentration. The specific process can be described as follows:
at a certain fixed oxygen concentrationUnder, the sensor temperature is set to +.>、/>Pump current of the measuring sensor at these two temperatures +.>、/>The relationship between the pump current and the oxygen concentration is known by the gas diffusion mechanism:
；
；
the above two formulas are subtracted, and the following are:
；
due to the operating temperature of the sensor、/>Is set as a value and measures the oxygen concentration in the gas>It is known that +.>The values are:
；
thus, the corrected K value is:
；
at this time, the relation between the sensor pump current and the oxygen concentration is:
。
the above calibration process can be accomplished with only a known oxygen concentration. When the automobile engine is in a closed state, namely the exhaust emission is zero, the gas component in the sensor cavity is the reference air, and the oxygen concentration in the air can be considered as a constant value, so that the on-line program calibration can be performed when the automobile is in idle load.
A sensor sensitivity correction flow chart is shown in fig. 3. The self-calibration routine is initiated when the engine is shut down, at which point the oxygen concentration measured by the sensor may be considered to be the air oxygen concentration. Firstly, working at a normal working temperature, namely 800 ℃, comparing the measured oxygen concentration with an air reference oxygen concentration, and if the error is less than 3%, exiting the calibration procedure due to the measurement error; if the error is greater than 3%, recording the measured value at the moment, setting the resistance value of the closed loop heating resistor to be a corresponding resistance value at 700 ℃, adjusting the working temperature of the sensor to be 700 ℃, then measuring again, calculating a new K value through the pump current value measured twice, writing the new K value into a boot area to cover the original K value, and then executing the calibration procedure again until the normal exit is achieved.
The foregoing is only a preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art, who is within the scope of the present invention, should make equivalent substitutions or modifications according to the technical scheme of the present invention and the inventive concept thereof, and should be covered by the scope of the present invention.
Claims (2)
1. The correction method is characterized in that the correction method is based on an oxygen diffusion mechanism, the relation among pump current, temperature and concentration of gas to be detected is determined, and on-line recalibration of sensitivity is performed by a temperature disturbance method, wherein the oxygen diffusion mechanism is as follows:t is the sensor temperature, < >>Is oxygen concentration, I P0 The method for correcting the sensitivity comprises the following specific steps of:
s1, at a certain fixed oxygen concentrationRespectively setting the sensor temperature as T 1 、T 2 Pump current of the measuring sensor at these two temperatures +.>The relationship between pump current and oxygen concentration obtained by a gas diffusion mechanism is:
s2, calculating delta I according to the pump currents at two temperatures P0 ，
S3, according to the working temperature T of the sensor 1 、T 2 And measuring the oxygen concentration in the gasThe value of the sensitivity K is calculated and,
s4, obtaining a sensitivity K value according to the S3, thereby determining the relation between the corrected sensor pump current and the oxygen concentration,
2. the method for calibrating sensitivity of a nitrogen-oxygen sensor according to claim 1, wherein the gas to be measured is oxygen, CO 2 ，NOx。
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0878709A2 (en) * | 1997-03-21 | 1998-11-18 | NGK Spark Plug Co. Ltd. | Method and apparatus for measuring NOx gas concentration |
| CN102928484A (en) * | 2012-11-09 | 2013-02-13 | 尚沃医疗电子无锡有限公司 | Gas sensor self-calibration method |
| DE102013200647A1 (en) * | 2012-01-17 | 2013-07-18 | Ngk Spark Plug Co., Ltd. | Correction coefficient setting method for a gas concentration detecting device, gas concentration detecting device and gas sensor |
| CN110487967A (en) * | 2019-08-26 | 2019-11-22 | 广西玉柴机器集团有限公司 | A kind of NOx sensor on-line correction method and signal pickup assembly using air |
| CN110501462A (en) * | 2014-02-19 | 2019-11-26 | 马林克罗特医疗产品知识产权公司 | Method for compensating for long term sensitivity drift of an electrochemical gas sensor exposed to nitric oxide |
-
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Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0878709A2 (en) * | 1997-03-21 | 1998-11-18 | NGK Spark Plug Co. Ltd. | Method and apparatus for measuring NOx gas concentration |
| DE102013200647A1 (en) * | 2012-01-17 | 2013-07-18 | Ngk Spark Plug Co., Ltd. | Correction coefficient setting method for a gas concentration detecting device, gas concentration detecting device and gas sensor |
| CN102928484A (en) * | 2012-11-09 | 2013-02-13 | 尚沃医疗电子无锡有限公司 | Gas sensor self-calibration method |
| CN110501462A (en) * | 2014-02-19 | 2019-11-26 | 马林克罗特医疗产品知识产权公司 | Method for compensating for long term sensitivity drift of an electrochemical gas sensor exposed to nitric oxide |
| CN110487967A (en) * | 2019-08-26 | 2019-11-22 | 广西玉柴机器集团有限公司 | A kind of NOx sensor on-line correction method and signal pickup assembly using air |
Non-Patent Citations (3)
| Title |
|---|
| "Numerical analysis and design for NOx sensor pump units decoupling control";Yuyang Cao等;《IEEE》;全文 * |
| NO_2电化学传感器的零点漂移校正研究;黄崇崇;胡仁志;谢品华;靳华伟;林川;;传感技术学报(第07期);全文 * |
| 溶氧表灵敏度校正中的电解氧法及存在问题分析;完颜绍会, 鲍克勤;上海电力学院学报(第02期);全文 * |
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