JP2020173143A - Constant potential electrolytic gas sensor - Google Patents

Abstract

To correct a calibration curve as necessary for a change in output specific to a constant-potential electrolytic gas sensor and accurately detect a fault or abnormality occurring to the sensor.SOLUTION: Provided is a constant-potential electrolytic gas sensor for determining, when correcting a calibration curve by a standard gas, whether the variation in output to detect falls within a prescribed width C so as not to be determined as abnormal by detecting the output that corresponds to a current value by the standard gas multiple times, as well as determining on the basis of a calibration curve that the gas concentration to be presented is abnormal in accordance with a current value occurring by the standard gas, or comparing for determination with a rated value A which is used to determine whether the calibration curve needs to be corrected and further comparing for determination with a rated value B in which the gas concentration to be presented is increased to be larger than for the rated value A and which is used to determine the abnormality of the gas sensor, and detecting the gas sensor abnormality in accordance with these determination results, or capable of determining whether or not the calibration curve needs to be corrected.SELECTED DRAWING: Figure 1

Description

The present invention relates to a constant potential electrolytic gas sensor and relates to a correction of a calibration curve with a standard gas.

The constant potential electrolytic gas sensor is an electrode (opposite electrode to the working electrode) formed by coating a gas permeable film on the side surface of an electrolytic solution tank containing an electrolytic solution and platinum having a catalytic action on the surface of the gas permeable film. And a reference electrode arranged in the electrolytic solution tank, and the potential difference between the working electrode and the reference electrode is kept constant by the potentiostat circuit. Then, the target gas that has passed through the gas permeable membrane undergoes ion exchange at the working electrode, and a counter reaction occurs at the counter electrode, so that an electrolytic current flows. The gas concentration is measured by utilizing the fact that this current is proportional to the target gas concentration.

In the constant potential electrolytic gas sensor having such a configuration, the volume of the electrolytic solution filled in the electrolytic solution tank may fluctuate due to changes in atmospheric pressure and ambient temperature. Sulfuric acid, which is often used as an electrolytic solution, has hygroscopicity, but when the gas sensor is placed in a high humidity environment, it takes in external water vapor due to the hygroscopicity of sulfuric acid and increases the amount of electrolytic solution to increase the amount of electrolytic solution. Volume increases. Such volume fluctuations in the electrolytic solution cause fluctuations in the internal pressure in the electrolytic solution tank, which may cause fluctuations in the output of the electrolytic current.

Further, the fluctuation of the internal pressure in the container due to the volume fluctuation of the electrolytic solution described above may cause the electrolytic solution to leak near the electrode, and the electrolytic solution leaking to the lead terminal connected to the electrode causes corrosion of the lead terminal. May bring.

Since the above-mentioned events that can occur in the constant-potential electrolytic gas sensor cause a decrease in detection accuracy and undetectability, the conventional constant-potential electrolytic gas sensor has also been dealt with.

For example, Patent Document 1 discloses a constant potential electrolytic gas sensor in which a gas accommodating portion is provided in an electrolytic solution tank. With this configuration, the gas contained in the gas accommodating portion absorbs the volume fluctuation of the electrolytic solution, and the fluctuation range of the internal pressure in the electrolytic solution tank is reduced, so that the detection accuracy can be prevented from being lowered and the detection failure can be prevented. ..

JP-A-2002-71621

The detection range of the constant potential electrolytic gas sensor is several hundred ppb to several tens of ppm, which is extremely high sensitivity. In addition, due to the feature that the selected gas can be selected by the set potential difference between the electrodes, it is possible to detect toxic gases such as carbon monoxide, hydrogen sulfide, silane, and arsine at low concentrations, so the operator can wear it. It is often used as a portable gas sensor. On the other hand, the useful life is relatively short, about one year.

A structural solution such as providing an air accommodating portion in the electrolytic solution tank as in the invention of Patent Document 1 to solve the problem caused by the volume fluctuation of the electrolytic solution brings about an increase in size of the gas sensor and impairs portability. Further, providing a complicated structure in the constant potential electrolytic gas sensor having a short service life of one year in the first place unnecessarily increases the cost for the service life. Rather, it is more cost effective to accurately grasp failures and abnormalities due to aging deterioration and replace them with new gas sensors.

Therefore, in the present invention, the calibration curve is appropriately corrected for the fluctuation of the output peculiar to the constant potential electrolytic gas sensor to prevent the measurement accuracy from being lowered, and the sensor is damaged or abnormal due to the volume fluctuation of the electrolytic solution. When it occurs, it is intended to be detected accurately.

In order to solve the above problems, in the present invention, the gas to be measured is reacted with molecules in a liquid solvent via a gas permeable membrane, and the current value and the gas concentration to be presented are determined according to the current value generated by the generated ions. It is a constant potential electrolytic gas sensor that presents the gas concentration based on the calibration curve showing the relationship between the above, and when the calibration curve is corrected by the standard gas that contains almost no gas to be measured, it corresponds to the current value by the standard gas. It is generated by a variation detection unit that detects the variation of the output by obtaining the output a plurality of times, a variation determination unit that determines whether the detected variation is within a predetermined width C for not determining an abnormality, and a standard gas. The first concentration to be compared with the specified value A used to judge whether the gas concentration to be presented based on the calibration curve according to the current value is abnormal or whether the calibration curve should be corrected. The value comparison determination unit, the second concentration value comparison determination unit for comparing and determining the gas concentration to be presented with the specified value B used for determining the abnormality of the gas sensor larger than the specified value A, and the abnormality. Provided is a constant potential electrolytic gas sensor having a control unit that controls the determination unit for detection and a correction unit that corrects a calibration curve according to the value of a current generated by a standard gas.

Further, it is a constant potential electrolytic gas sensor having the above configuration, and the control unit is a constant potential electrolytic type having a first operating means for operating the variation determination unit and the first concentration value comparison determination unit in this order as long as no abnormality is determined. Provides a gas sensor.

Further, in the case of a constant potential electrolytic gas sensor having the above configuration, the control unit determines that the determination result in the first concentration value comparison determination unit is abnormal or that the calibration curve must be corrected. Provided is a constant potential electrolytic gas sensor having a second operating means for operating the second concentration value comparison determination unit next.

Further, in the constant potential electrolytic gas sensor having the above configuration, the control unit operates the correction unit when the determination result in the second concentration value comparison determination unit is the determination result that the gas sensor is not abnormal. A constant potential electrolytic gas sensor having a third operating means is provided.

Further, in the constant potential electrolytic gas sensor having the above configuration, the correction unit provides a first correction means for correcting the calibration curve so that the gas concentration to be presented becomes 0 according to the value of the current generated by the standard gas. Provided is a constant potential electrolytic gas sensor having.

Further, in the constant potential electrolytic gas sensor having the above configuration, the correction unit corrects the calibration curve so that the value obtained by multiplying the gas concentration in the standard gas by the pre-correction calibration curve by a predetermined coefficient is the correction amount. Provided is a constant potential electrolytic gas sensor having a second correction means.

Further, the constant potential electrolytic gas sensor having the above configuration, the correction unit has a selection receiving means for accepting the selection of whether to perform the correction this time by the first correction means or the correction this time by the second correction means. A potential electrolysis gas sensor is provided.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a constant potential electrolytic gas sensor capable of preventing a decrease in detection accuracy caused by volume fluctuation of an electrolytic solution and accurately determining an abnormality of a gas sensor.

Conceptual diagram showing an example of the functional configuration of the constant potential electrolytic gas sensor of the first embodiment Conceptual diagram showing the basic configuration of a constant potential electrolytic gas sensor Conceptual diagram for explaining a predetermined width C Conceptual diagram showing the number of times standard gas was measured and the gas concentration value at that measurement time Conceptual diagram showing the number of times standard gas was measured and the gas concentration value at that measurement time Conceptual diagram showing an example of the hardware configuration of the constant potential electrolytic gas sensor of the first embodiment Flow chart showing an example of the processing flow when correcting the calibration curve with standard gas A flow chart showing another example of the processing flow when the calibration curve is corrected by the standard gas. A flow chart showing another example of the processing flow when the calibration curve is corrected by the standard gas. Conceptual diagram showing an example of the functional configuration of the constant potential electrolytic gas sensor of the second embodiment Conceptual diagram showing an example of the functional configuration of the constant potential electrolytic gas sensor of the third embodiment Conceptual diagram showing an example of the functional configuration of the constant potential electrolytic gas sensor of the fourth embodiment. Conceptual diagram showing an example of the functional configuration of the constant potential electrolytic gas sensor of the fifth embodiment. Conceptual diagram showing an example of the functional configuration of the constant potential electrolytic gas sensor of the sixth embodiment. Conceptual diagram showing the change in gas concentration value to be presented when the calibration curve is corrected by the second correction means.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The present invention should not be limited to these embodiments, and may be implemented in various embodiments without departing from the gist thereof.

In the first embodiment, claim 1 will be mainly described. In the second embodiment, claim 2 will be mainly described. In the third embodiment, claim 3 will be mainly described. In the fourth embodiment, claim 4 will be mainly described. The fifth embodiment mainly describes the fifth aspect. The sixth embodiment mainly describes claims 6 and 7.
<Embodiment 1>
<Outline of Embodiment 1>

In the invention of the first embodiment, the variation of the gas sensor output before the concentration conversion and the converted concentration value are compared with the respective specified values, and the calibration curve is corrected by the standard gas and the abnormality of the gas sensor is determined.
<Embodiment 1 Configuration>

FIG. 1 is a conceptual diagram showing an example of the functional configuration of the constant potential electrolytic gas sensor of the present embodiment. As shown in the figure, the "constant potential electrolytic gas sensor" 0100 of the present embodiment includes a "control unit" 0101, a "variation detection unit" 0102, a "variation determination unit" 0103, and a "first concentration value comparison determination unit". 0104, a "second density value comparison determination unit" 0105, and a "correction unit" 0106.

In addition, each functional configuration described below can be realized as a combination of hardware and software. Specifically, if a computer is used, the CPU, main memory, bus, or secondary storage device (nonvolatile memory such as flash memory or SSD, storage media such as CD or DVD, and read drive for those media). Etc.), hardware components such as input devices used for information input, printing devices and display devices, and other external peripheral devices, as well as interfaces for the external peripheral devices, communication interfaces, and to control those hardware. Driver programs, other application programs, user interface applications, etc. Then, by the arithmetic processing of the CPU according to the program expanded on the main memory, the data input from the input device or other interface and stored on the memory or hard disk is processed and accumulated, or the above hardware or each of the above hardware Instructions to control the software are generated. Alternatively, the functional block of the present device may be realized by dedicated hardware. Further, it may be provided with a gas introduction mechanism, a sensor installation structure, a chamber for measurement, or a gas flow path for measurement.

Moreover, each embodiment described in this specification can be realized not only as an apparatus but also a part or all of it as a method. Further, a part of such a device can be configured as software. Further, a software product used to make a computer execute such software, and a recording medium on which the product is fixed are naturally included in the technical scope of each embodiment described in the present specification (the present specification). The same is true throughout.)

Before explaining the configuration of each of the above parts, the basic configuration of the constant potential electrolytic gas sensor will be described with reference to FIG.

The constant potential electrolysis type gas sensor is a "gas permeable film" in which a "gas permeable film" 0203 in which a "working electrode" 0202 is laminated on the upper surface of a "plastic container" 0201 having an upper and lower openings and a "gas permeable film" in which a "counter electrode" 0204 is laminated on the lower surface of the container "0205" is arranged, and "reference electrode" 0206 is arranged in the container, and the liquid solvent of the electrolyte is filled.

The gas permeable membrane is a membrane that does not allow liquid to permeate but allows only gas to permeate, and for example, a porous membrane made of fluororesin such as a PTFE film (polytetrafluoroethylene membrane) is used. For electrodes such as working electrodes, a metal powder or granular material having a catalytic action such as platinum or gold is coated on the surface of a gas permeable membrane, or the metal powder or granular material is kneaded and fired with a binder to form a thin film. It is constructed by superimposing the above-mentioned material on a gas-permeable membrane.

Then, a potentiometer circuit is used to maintain a specific potential difference between the working electrode and the reference electrode. In such a state, when CO (carbon monoxide), which is a gas to be measured, comes into contact with the working electrode as shown in the figure, the following chemical reactions occur at each of the working electrode and the counter electrode.
Working electrode: CO + H ₂ O → CO ₂ + 2H ⁺ + 2e ^{−
_{Counter: 1 / 2O 2 + 2H +}} + 2e - → H 2 O
Total reaction: CO + 1 / 2O ₂ → CO ₂
Due to this chemical reaction, an electrolytic current flows between the working electrode and the counter electrode, and this electrolytic current value can be obtained as an output, converted into a CO gas concentration value based on a predetermined calibration curve, and presented. By appropriately selecting the potential difference between the working electrode and the reference electrode and the electrolytic solution, it is possible to measure the concentration of not only CO gas but also various gases.

This embodiment is characterized in the process of correcting the calibration curve with a standard gas that does not contain a measurement target gas such as CO gas in the constant potential electrolytic gas sensor as described above. The correction of the calibration curve by the standard gas is to correct the calibration curve so that the gas concentration of the gas to be measured presented by the gas sensor approaches 0 or 0 when the standard gas is measured. Each configuration shown in FIG. 1 will be described below. The timing of correction of the calibration curve by the standard gas is not particularly limited, but may be performed based on, for example, an instruction input by the user, or may be automatically performed based on a predetermined schedule.

First, the "control unit" 0101 controls a variation determination unit, a first concentration value comparison determination unit, and a second concentration value comparison determination unit, which will be described later, in order to detect an abnormality. For example, the operation conditions and operation order of each judgment unit are controlled. In addition, each determination unit may be configured to control the setting or change of a specified value as a criterion for determination.

The “variation detection unit” 0102 has a function of detecting variations in the output by obtaining an output corresponding to the current value of the standard gas a plurality of times at the timing of correction of the calibration curve. The standard gas is a gas that contains almost no gas to be measured, and when the gas to be measured is a type of gas that is not normally contained in air, such as CO gas, hydrogen gas, and hydrogen sulfide gas, it is generally used. Uses air. When a gas that requires oxygen for a chemical reaction that causes an electrolytic current is to be measured, a standard gas containing oxygen is used. Further, the current value due to the standard gas means an electrolytic current value generated by exposing the working electrode to the standard gas. Further, the output corresponding to the current value may be the current value itself or a value obtained by converting the current value into a voltage value.

The output variation according to the current value due to the standard gas may be caused by an error of the gas sensor element itself, an error at the time of AD conversion, an error of the amplifier circuit, or the like. It can be said that it is normal for the gas sensor to have some variation, but if the variation is larger than the normal level, it is possible that the gas sensor is in an abnormal state such as failure or damage. Is high. Therefore, the variation detection unit detects the output variation in order to determine the abnormality of the gas sensor by the variation determination unit described later. There are various specific modes of the variation of the output to be detected, and it is assumed that it corresponds to the width C defined by the variation determination unit.

The "variation determination unit" 0103 uses a predetermined width C for determining whether the variation of the output detected by the variation detection unit is abnormal or not, and determines whether the variation is within the predetermined width C. Has. The predetermined width C is, for example, the width from the minimum value to the maximum value, the width from the first quartile to the third quartile, and the center value −σ from the output value acquired multiple times by a normal gas sensor. It is specified by the center value + σ from (standard deviation).

FIG. 3 is a diagram showing an output value acquired a plurality of times in succession and a predetermined width C as a line graph. The horizontal axis is the number of times the output value is acquired, and the vertical axis is the output value. The output value may be a current value or a voltage value. Further, since the output value takes various values depending on the sensor, the output value shown on the vertical axis is a relative value for explanation.

As shown in the figure, there are many output values outside the width C in the output values for 50 times. Therefore, when such a variation in the output value is detected, the variation determination unit determines that the gas sensor is abnormal. More specifically, it can be determined by the ratio seen from the whole within the variation range of the width C of the measurement points, such that a predetermined percentage of the variation of the measurement points, for example, 100% or 90%, is within the variation width C. The preferable ratio is about 90% to 100%. Further, it can be determined that the standard deviation specified amount of the variation of the measurement points is within the variation width C. The standard deviation specified amount is represented by, for example, plus or minus 2 sigma or plus or minus 2.3 sigma. When specified by the standard deviation, the value is preferably in the range of plus or minus 2 sigma to plus or minus 3 sigma. Alternatively, it may be specified by the magnitude of the standard deviation. How large the standard deviation is with respect to the mean value. If the variation is large with respect to the average value, the possibility of gas sensor abnormality increases. The magnitude of the standard deviation is preferably about 20% to 30% with respect to the average value.

The "first concentration value comparison determination unit" 0103 determines that the gas concentration to be presented based on the calibration curve is abnormal according to the value of the current generated by the standard gas, or determines whether the calibration curve must be corrected. It has a function to compare and judge with the specified value A used for the purpose.

The gas concentration to be presented when the standard gas is introduced should be 0 ppm if it is assumed that the gas to be measured is not contained in the standard gas. If the concentration of gas contained in the standard gas is estimated in advance, the estimated gas concentration should be presented. Further, even if the measured gas concentration value deviates from the expected gas concentration value, no problem can be measured by correcting the calibration curve as long as the drift is within the allowable drift range of the gas sensor. On the other hand, if the deviation between the measured gas concentration value and the assumed gas concentration value exceeds the allowable drift range, it is determined that the measured gas concentration value is abnormal and the gas sensor is abnormal. ..

The first concentration value comparison judgment unit is based on the difference between the displayed gas concentration value converted by the calibration curve by the measurement of the standard gas and the above-mentioned assumed gas concentration value, and whether or not the gas sensor is abnormal or the calibration curve needs to be corrected. To judge. Then, the determination is made based on whether the deviation width with respect to the assumed gas concentration value exceeds the specified value A. If it exceeds the specified value plus or minus A (absolute value A), at least measures such as correction of the calibration curve are required, and if it greatly exceeds it, correction cannot be taken, and the sensor itself is abnormal and should be replaced. Give the user information that there is no choice but to do it.

FIG. 4 is a conceptual diagram showing the number of times the display gas concentration value of the standard gas is compared with the specified value A and the display gas concentration value (ppm) at the time of comparison. In this figure, it is assumed that the gas to be measured is not included in the standard gas, and the specified value A is set to “5 ppm”. Here, since the specified value is a value that defines the deviation width, if it exceeds the range of −5 ppm to + 5 ppm, it is determined that an abnormality must be made or the calibration curve must be corrected. (Whether it is an abnormality judgment or a correction necessity judgment is judged by a separate judgment standard.)

In the figure, the specified range is indicated by the shaded area, and the gas concentration values from 0 to 6 times are within the specified range, but exceed the range at the time of the 7th comparison. The first concentration value comparison determination unit determines that the abnormality determination or the correction of the calibration curve must be performed based on the result of the seventh measurement. Such a judgment may be judged or judged immediately when the range specified by the specified value is exceeded, or may be judged or judged when the result exceeding the range occurs a predetermined number of times in succession. You may.

The "second concentration value comparison determination unit" 0104 has a function of comparing and determining the gas concentration to be presented with the specified value B used for determining the abnormality of the gas sensor, which is larger than the specified value A. FIG. 5 is a conceptual diagram showing the number of times the displayed gas concentration value converted by the calibration curve by the measurement of the standard gas is compared with the specified value B and the displayed gas concentration value at the comparison time. Here, the specified value A is "5 ppm", and the specified value B is "20 ppm", which is larger than the specified value A. The specified value B is also a value that defines the range of the gas concentration value as in the specified value A, and the range specified by the specified value B is in the range of −20 ppm to +20 ppm. In the figure, the scale lines of −20 ppm and + 20 ppm are shown by thick dotted lines. Although the displayed gas concentration value is a negative value in the figure, this is a calculated value inside the device of this gas sensor and is not actually presented to the gas sensor user. At least, while processing for correction of the calibration curve and determination of abnormality of the gas sensor is being performed, for example, a display displaying the gas concentration value displays "0 ppm" or the like. The same applies to the first concentration value comparison determination unit described above.

In the figure, the displayed gas concentration value at the 18th time is less than −20 ppm, and the second concentration value comparison determination unit determines that the gas sensor is abnormal when such a result is obtained. Based on this determination, it may be configured to display that the gas sensor is abnormal or to display for replacing the gas sensor. Further, when the displayed gas concentration value exceeds the specified value A but does not exceed the specified value B, it can be seen that the gas sensor is not abnormal but the calibration curve needs to be corrected.

As described above, the second concentration value comparison determination unit functions to discriminate between the situation where the gas sensor is abnormal and the situation where the calibration curve needs to be corrected. Further, the first concentration value comparison determination unit can determine the situation in which the gas sensor is not abnormal and the calibration curve does not need to be corrected. Therefore, the functions of the first concentration value comparison determination unit and the second concentration value comparison determination unit can determine the above three situations that may occur in the gas sensor, in addition to the abnormality determination by the variation determination unit.

The “correction unit” 0106 has a function of correcting the calibration curve according to the value of the current generated by the standard gas. The execution of the correction is based on the judgment result of the first concentration value comparison judgment unit and the judgment result of the second concentration value comparison judgment unit. For example, the judgment result of the first concentration value comparison judgment unit is abnormal or the calibration curve must be corrected, and the judgment result of the second concentration value comparison judgment unit is that the gas sensor is abnormal. If not, the calibration curve is corrected. This is because the value of the current generated by the standard gas and the display gas concentration converted based on the calibration curve do not fall within the range of the gas concentration specified by the specified value A, and also fall within the range of the gas concentration specified by the specified value B. It means that the calibration curve is corrected when it is.
<Embodiment 1 Hardware>

FIG. 6 is a conceptual diagram showing an example of the hardware configuration of the constant potential electrolytic gas sensor of the present embodiment. As shown in the figure, the constant potential electrolytic gas sensor is a constant potential electrolytic type via a CPU 0601, a non-volatile memory (for example, ROM, SSD, etc.) 0602, a main memory 0603, an interface I / F0604, and an I / F. The gas sensor element 0605 and the display 0606 of the above are provided, and a system bus 0607 for exchanging and transmitting signals between them is provided.

The non-volatile memory includes a variation detection program that detects variations in the output by obtaining outputs corresponding to the current value of the standard gas a plurality of times, and a predetermined width C for preventing the detected variations from being determined as abnormal. The variation judgment program that determines whether the gas is within the standard gas and the gas concentration that should be presented based on the calibration curve according to the value of the current generated by the standard gas are determined to be abnormal, or whether the calibration curve must be corrected. The first concentration value comparison judgment program for comparing and judging with the specified value A used for the purpose, and the specified value B used for judging the abnormality of the gas sensor in which the gas concentration to be presented is larger than the specified value A. A second concentration value comparison judgment program for comparison and judgment, a control program for controlling the execution of the judgment program to detect the abnormality, a correction program for correcting the calibration curve according to the value of the current generated by the standard gas, and the like. Information such as various programs, a calibration curve, a specified value A, a specified value B, and a width C is held. Further, the non-volatile memory holds the current value, the determination result, and the like generated by the standard gas acquired by executing each of the above programs. Then, the main memory expands and executes each of the above-mentioned programs stored in the non-volatile memory, makes a judgment, corrects the calibration curve according to the judgment result, or notifies an abnormality of the gas sensor.
<Implementation 1 Processing Flow>

FIG. 7 is a flow chart showing an example of a processing flow when the calibration curve is corrected by the standard gas in the constant potential electrolytic gas sensor or the abnormality determination of the gas sensor is performed. The following flow is based on the premise that the standard gas contains almost no gas to be measured. As shown in the figure, first, the variation in the output is detected by obtaining the output corresponding to the current value of the standard gas a plurality of times in the gas flowing through the gas flow path (S0701). Then, it is determined whether or not the detected variation is within the predetermined width C for not being determined as abnormal (S0702). If it does not fit in the width C, it is determined to be abnormal and reported (S0703). On the other hand, when it is within the width C, the display gas concentration of the measurement target converted from the output corresponding to the current value by the standard gas and the calibration curve is acquired (S0704). Then, it is determined whether the absolute value of the acquired displayed gas concentration is smaller than the specified value A (| gas concentration | <specified value A). (S0705). If the judgment result is smaller than the specified value A, the process ends. On the other hand, if the determination result is not smaller than the specified value A, it is determined whether the acquired absolute value of the displayed gas concentration is smaller than the specified value B (| gas concentration | <specified value B) (S0706). If the result is determined to be smaller than the specified value B, the calibration curve is corrected (S0707) and the process ends. On the other hand, if it is determined that the value is not smaller than the specified value B, it is determined that the value is abnormal, a report is made (S0703), and the process ends.

The process of determining an abnormality and reporting is different depending on the case based on the judgment result using the width C and the case based on the judgment result using the specified value B, and the content of the report is determined according to each case. And so on.

FIG. 8 is a flow chart showing another example of the processing flow when the calibration curve is corrected by the standard gas in the constant potential electrolytic gas sensor or the abnormality determination of the gas sensor is performed. As shown in the figure, first, the display gas concentration of the measurement target converted from the output corresponding to the current value of the standard gas and the calibration curve is acquired (S0801). Then, it is determined whether the absolute value of the acquired displayed gas concentration is smaller than the specified value A (| gas concentration | <specified value A). (S0802). If the result is determined to be smaller than the specified value A, the variation in the output is detected by obtaining the output corresponding to the current value of the standard gas a plurality of times in the gas flowing through the gas flow path (S0803). Then, it is determined whether or not the detected variation is within the predetermined width C for not being determined to be abnormal (S0804). If it fits in the width C, it ends. On the other hand, if it does not fit in the width C, it is determined to be abnormal and a report is made (S0805).

If the result of the comparison judgment of S0802 is not smaller than the specified value A, it is judged whether the absolute value of the acquired displayed gas concentration is smaller than the specified value B (| gas concentration | <specified value B) (| S0806). If it is determined that the value is not smaller than the specified value B, it is determined that the value is abnormal, a report is made (S0805), and the process ends. On the other hand, if it is determined that the value is smaller than the specified value B, the above-mentioned output variation is detected (S0807). Then, it is determined whether or not the detected variation is within the width C described above (S0808). If it does not fit in the width C, it is determined to be abnormal and a report is made (S0805). On the other hand, if it is within the width C, the calibration curve is corrected (S0809) and the process ends.

FIG. 9 is a flow chart showing still another example. As shown in the figure, first, the display gas concentration of the measurement target converted from the output corresponding to the current value of the standard gas and the calibration curve is acquired (S0901). Then, it is determined whether the absolute value of the acquired displayed gas concentration is smaller than the specified value B (| gas concentration | <specified value B) (S0902). If it is determined that the value is not smaller than the specified value B, it is determined that the value is abnormal, a report is made (S0903), and the process ends. On the other hand, in the case of the determination result that it is smaller than the specified value B, it is determined whether the absolute value of the acquired displayed gas concentration is smaller than the specified value A (| gas concentration | <specified value A). (S0904). If the result is determined to be smaller than the specified value A, the variation in the output is detected by obtaining the output corresponding to the current value of the standard gas a plurality of times in the gas flowing through the gas flow path (S0905). Then, it is determined whether or not the detected variation is within the predetermined width C for not being determined to be abnormal (S0906). If it does not fit in the width C, it is determined to be abnormal and reported (S0903). On the other hand, if it fits in the width C, it ends.

When the result of the comparison determination in S0904 is not smaller than the specified value A, the above-mentioned output variation is detected (S0907). Then, it is determined whether or not the detected variation is within the width C described above (S0908). If it does not fit in the width C, it is determined to be abnormal and reported (S0903). On the other hand, if it fits in the width C, the calibration curve is corrected (S0909) and the process ends.

Further, in the above flow, each judgment process is performed by the control unit or the control program so that the judgment using the width C, the judgment using the specified value A, and the judgment using the specified value B are performed in a series of flows. Although it is controlled, each judgment process may be controlled to be performed as an individual process flow.
<Effect of Embodiment 1>

According to this embodiment, it is possible to correct the calibration curve as necessary for the fluctuation of the output peculiar to the constant potential electrolytic gas sensor, and to accurately detect the occurrence of a failure or abnormality in the gas sensor.
<Embodiment 2>
<Outline of Embodiment 2>

The constant potential electrolytic gas sensor of the present embodiment is based on the first embodiment, and is configured to operate the control unit in the order of the variation determination unit and the first concentration value comparison determination unit as long as no abnormality is determined.
<Embodiment 2 Configuration>

FIG. 10 is a conceptual diagram showing an example of the functional configuration of the constant potential electrolytic gas sensor of the present embodiment. As shown in the figure, the "constant potential electrolytic gas sensor" 1000 of the present embodiment includes a "control unit" 1001 having a "first operating means" 1007, a "variation detection unit" 1002, and a "variation determination unit" 1003. , "First concentration value comparison determination unit" 1004, "second concentration value comparison determination unit" 1005, and "correction unit" 1006. The configuration other than the control unit is the same as the configuration of the same name in the constant potential electrolytic gas sensor of the first embodiment. Therefore, the control unit will be described here, and the description of other configurations will be omitted.

The "first operating means" 1007 has a function of operating the variation determination unit and the first concentration value comparison determination unit in this order as long as no abnormality is determined.

As described in the first embodiment, the variation determination unit makes a determination using the width C, and if the variation is within the width C, it is not determined to be abnormal. Then, when it is not determined to be abnormal, the first concentration value comparison determination unit for comparison determination using the specified value A is subsequently operated. Therefore, when the result obtained by operating the variation determination unit is a determination result that is abnormal, the first concentration value comparison determination unit is not operated.

The hardware configuration of the present embodiment can be realized according to the hardware configuration of the first embodiment, and further, the first operation of operating the variation determination unit and the first concentration value comparison determination unit in this order as long as no abnormality is determined. This can be achieved by holding the program and executing it as appropriate.

Further, since the processing flow of the present embodiment is included in the processing flow of the first embodiment described with reference to FIG. 7, the description thereof will be omitted.
<Effect of Embodiment 2>

According to the present embodiment, when an abnormality is determined as a result of the determination based on the variation and the width C, the comparison determination between the gas concentration value and the specified value A is not performed. Therefore, it is not necessary to perform an operation in the first concentration value comparison determination unit, which is useless.
<Embodiment 3>
<Outline of Embodiment 3>

The constant potential electrolytic gas sensor of the present embodiment is based on the first or second embodiment, and the control unit operates the second concentration value comparison determination unit next according to the determination result of the first concentration value comparison determination unit. It is configured.
<Structure 3 of Embodiment>

FIG. 11 is a conceptual diagram showing an example of the functional configuration of the constant potential electrolytic gas sensor of the present embodiment. As shown in the figure, the "constant potential electrolytic gas sensor" 1100 of the present embodiment includes a "control unit" 1101 having a "first operating means" 1107 and a "second operating means" 1108, and a "variation detecting unit" 1102. , "Variation determination unit" 1103, "first density value comparison determination unit" 1104, "second density value comparison determination unit" 1105, and "correction unit" 1106. The configuration other than the control unit is the same as the configuration of the same name in the constant potential electrolytic gas sensor of the first or second embodiment. Therefore, the control unit will be described here, and the description of other configurations will be omitted.

The "second operating means" 1108 uses the second density value comparison judgment unit when the judgment result in the first concentration value comparison judgment unit is abnormal or the judgment result is that the calibration curve must be corrected. It has a function to operate next.

As described in the first or second embodiment, the first concentration value comparison determination unit acquires the gas concentration to be presented based on the value of the current generated by the standard gas and the calibration curve. Then, by comparing the acquired gas concentration with the specified value A, it is determined whether the gas concentration is abnormal or the calibration curve needs to be corrected. When it is determined that the gas concentration is abnormal or the calibration curve needs to be corrected, the second operating means further operates the second concentration value comparison determination unit for comparison and determination using the specified value B.

The hardware configuration of the present embodiment can be realized according to the hardware configuration of the first or second embodiment, and the judgment result in the first concentration value comparison judgment unit must be abnormal or the calibration curve must be corrected. If it is a determination result that the result is not satisfied, it can be realized by holding a second operation program for operating the second concentration value comparison determination unit next and executing it as appropriate.

Further, since the processing flow of the present embodiment is included in the processing flow of the first embodiment described with reference to FIG. 7, the description thereof will be omitted.
<Effect of Embodiment 3>

If it is determined that the gas concentration is not abnormal and the calibration curve does not need to be corrected by comparison with the specified value A, the operation of the second concentration value comparison determination unit is unnecessary. According to the present embodiment, when the gas concentration is not abnormal and the calibration curve does not need to be corrected, it is not necessary to perform the operation in the second concentration value comparison determination unit by the second operating means.
<Embodiment 4>
<Outline of Embodiment 4>

The constant potential electrolytic gas sensor of the present embodiment is based on any one of the first to third embodiments, and the control unit is configured to operate the correction unit according to the determination result of the second concentration value comparison determination unit. ..
<Structure of Embodiment 4>

FIG. 12 is a conceptual diagram showing an example of the functional configuration of the constant potential electrolytic gas sensor of the present embodiment. As shown in the figure, the "constant potential electrolytic gas sensor" 1200 of the present embodiment is a "control unit" 1201 having "first operating means" 1207, "second operating means" 1208, and "third operating means" 1209. From the "variation detection unit" 1202, the "variation determination unit" 1203, the "first density value comparison determination unit" 1204, the "second density value comparison determination unit" 1205, and the "correction unit" 1206. Become. The configuration other than the control unit is the same as the configuration of the same name in any of the constant potential electrolytic gas sensors of the first to third embodiments. Therefore, the control unit will be described here, and the description of other configurations will be omitted.

The "third operating means" 1209 has a function of operating the correction unit when the control unit determines that the determination result of the second concentration value comparison determination unit is not an abnormality of the gas sensor.

As described in the first to third embodiments, the second concentration value comparison determination unit compares the value of the current generated by the standard gas with the gas concentration to be presented based on the calibration curve and the specified value B. The third operating means operates the correction unit to correct the calibration curve when a determination result that the gas sensor is not abnormal is obtained by the comparison.

The hardware configuration of the present embodiment can be realized according to any of the hardware configurations of the first to third embodiments, and the judgment result of the control unit in the second concentration value comparison determination unit is not an abnormality of the gas sensor. If it is the result of the determination, it can be realized by holding the third operation program that operates the correction unit and executing it as appropriate.

Further, since the processing flow of the present embodiment is included in the processing flow of the first embodiment described with reference to FIG. 7, the description thereof will be omitted.
<Effect of Embodiment 4>

If the gas sensor is judged to be abnormal by comparison with the specified value B, the above notification and other processing should be performed, and there is no need to correct the calibration curve. The third operating means of the present embodiment eliminates the need for unnecessary correction of the calibration curve.
<Embodiment 5>
<Outline of Embodiment 5>

The constant potential electrolytic gas sensor of the present embodiment is based on any one of the first to fourth embodiments, and is configured such that the correction of the calibration curve by the correction unit is corrected so that the gas concentration by the standard gas becomes zero. There is.
<Configuration 5>

FIG. 13 is a conceptual diagram showing an example of the functional configuration of the constant potential electrolytic gas sensor of the present embodiment. As shown in the figure, the "constant potential electrolytic gas sensor" 1300 of the present embodiment includes a "control unit" 1301, a "variation detection unit" 1302, a "variation determination unit" 1303, and a "first concentration value comparison determination unit". 1304, a "second concentration value comparison determination unit" 1305, and a "correction unit" 1306 having a "first correction means" 1307. The control unit may have any of the first to third operating means. The configuration other than the correction unit is the same as the configuration of the same name in the constant potential electrolytic gas sensor of the first embodiment. Therefore, the correction unit will be described here, and the description of other configurations will be omitted.

The "first correction means" 1307 has a function of correcting the calibration curve so that the gas concentration to be presented becomes 0 according to the value of the current generated by the standard gas.

When the first concentration value comparison judgment unit and the second concentration value comparison judgment unit determine that the calibration curve needs to be corrected, the calibration curve is corrected by the first correction means to present the gas. The density error is corrected.

The hardware configuration of the present embodiment can be realized according to any of the hardware configurations of the first to fourth embodiments, and the gas concentration to be presented by the correction unit according to the value of the current generated by the standard gas is determined. This can be achieved by holding a first correction program that corrects the calibration curve so that it becomes 0 and executing it as appropriate. Further, since the processing flow of the present embodiment is the same as the processing flow of the first embodiment described with reference to FIG. 7, the description thereof will be omitted.
<Effect of Embodiment 5>

According to the constant potential electrolytic gas sensor of the present embodiment, when it is determined that the correction of the calibration curve is necessary, the calibration curve is corrected, so that the error of the presented gas concentration is corrected.
<Embodiment 6>
<Outline of Embodiment 6>

The constant potential electrolytic gas sensor of the present embodiment is based on any one of the first to fifth embodiments, and is configured to correct the calibration curve with a correction amount according to a predetermined coefficient.
<Structure 6 of Embodiment>

FIG. 14 is a conceptual diagram showing an example of the functional configuration of the constant potential electrolytic gas sensor of the present embodiment. As shown in the figure, the "constant potential electrolytic gas sensor" 1400 of the present embodiment includes a "control unit" 1401, a "variation detection unit" 1402, a "variation determination unit" 1403, and a "first concentration value comparison determination unit". 1404, a "second concentration value comparison determination unit" 1405, and a "correction unit" 1406 having a "first correction means" 1407 and a "second correction means" 1408. The control unit may have any of the first to third operating means. The configuration other than the correction unit is the same as the configuration of the same name in the constant potential electrolytic gas sensor of the first embodiment. Therefore, the correction unit will be described here, and the description of other configurations will be omitted.

The "second correction means" 1408 has a function of correcting the calibration curve so that the value obtained by multiplying the gas concentration in the standard gas by the pre-correction calibration curve by a predetermined coefficient is the correction amount.

For example, when the gas concentration X in the standard gas does not fall within the width specified by the specified value A and falls within the width specified by the specified value B, the first concentration value comparison determination unit and the second concentration value comparison The judgment unit determines that the calibration curve needs to be corrected. Here, when the calibration curve is corrected by the first correction means in the fifth embodiment, the calibration curve is presented as 0 when the current value that is the basis of the gas concentration X is output. The correction is made. If the current value generated by the standard gas is not changed by this correction, the gas concentration of 0 is presented based on the corrected calibration curve.

On the other hand, in the correction of the calibration curve by the second correction means, the correction amount is 0.2X, which is a value obtained by multiplying the gas concentration X by a coefficient such as 20%. As a result, the power value converted to the concentration 0.8X based on the calibration curve before correction is corrected to the calibration curve corresponding to the gas concentration 0. With the correction amount by this correction, there is still a deviation between the output by the standard gas at the time of the previous measurement and the calibration curve. Therefore, it is preferable to subsequently correct the calibration curve. In this case, the correction amount is corrected by multiplying the remaining deviation amount of 0.8X by the coefficient of 20%.

While making corrections step by step in this way, it is preferable to continuously measure the standard gas. For example, is it necessary to convert the current value of the standard gas into a concentration based on the calibration curve at the start of correction each time the correction is made, and to correct the concentration value by the first concentration value comparison judgment unit and the second comparison judgment unit? to decide. Then, when it is determined that the correction is necessary, the correction amount is corrected by multiplying the above-mentioned coefficient. On the other hand, when it is determined that the correction is not necessary, the calibration curve is corrected so that the gas concentration corresponding to the current value on which the correction is based becomes 0, and the correction by the second correction means is completed. .. FIG. 15 is a conceptual diagram showing a change in the gas concentration value to be presented when the calibration curve is corrected by the second correction means.

FIG. 15A shows a case where the coefficient is 20%, and FIG. 15B is a diagram showing a case where the coefficient is 50%. The horizontal axis shows the number of measurements of the standard gas, the vertical axis shows the gas concentration value converted according to the current value of the standard gas, and the concentration is consistently plotted at 5 ppm at the circles in the figure. Is a gas concentration value corresponding to the power value at each measurement based on the calibration curve at the start of correction. That is, there is no change in the concentration of the gas to be measured in the actual standard gas. Then, what is plotted by the square points in the figure is the gas concentration value based on the calibration curve corrected for each measurement. In this case, the specified value A is set to 0.5 ppm.

As shown in FIG. 15A, the gas concentration value to be presented in the fifth measurement is 5 ppm, which exceeds the specified value of 0.5 ppm, and it is judged that the calibration curve needs to be corrected. Then, the correction amount is 1 ppm, which is a value obtained by multiplying the gas concentration value of 5 ppm at this time by a coefficient of 20%. By correcting this calibration curve, the gas concentration value to be presented becomes 4 ppm. Subsequently, even in the sixth measurement, the gas concentration value indicated by the circle remains the value at which it is judged that the calibration curve needs to be corrected. Therefore, the calibration curve is corrected with 0.8 ppm, which is a value obtained by multiplying the remaining deviation amount of 4 ppm by 20%, which is a coefficient, as the correction amount. The gas concentration value to be presented by this corrected calibration curve is 3.2 ppm. When the gas concentration value based on the calibration curve corrected by repeating the corrections in this way falls below the specified value A (15th time), the series of corrections is completed. On the other hand, as shown in FIG. 15B, when the coefficient that defines the correction amount is increased, the number of measurements until the gas concentration value falls within the specified value A decreases, and the series of corrections ends relatively quickly.

When the constant potential electrolytic gas sensor is exposed to a high concentration of the gas to be measured that exceeds the measurement range, the gas to be measured may be adsorbed on the electrode and temporarily remain. In this case, the gas concentration value based on the current value generated by the standard gas can be so high that the calibration curve needs to be corrected. However, if the correction is performed with a large coefficient at this time, the calibration curve is greatly corrected in a short time. Is done. However, the effect of the remaining gas is temporary, and after the effect disappears, the gas concentration measurement value by the corrected calibration curve contains an error, which is inconvenient. By reducing the coefficient and gently correcting the calibration curve, it is easy to use because large measurement errors are unlikely to occur even for temporary effects such as exposure to high-concentration gas. On the other hand, when fluctuations in humidity, atmospheric pressure, etc. are expected during measurement, it is preferable to promptly correct the calibration curve according to the fluctuations because it contributes to maintaining the measurement accuracy.

By appropriately setting the coefficient that defines the correction amount, it is possible to correct the calibration curve suitable for the measurement environment and measurement mode. Further, the constant potential electrolytic gas sensor of the present embodiment may be provided with a configuration for accepting the setting of the coefficient in the second correction means.

Further, the correction unit may have a selection receiving means for accepting the selection of whether the correction is performed by the first correction means described in the fifth embodiment or the correction is performed by the second correction means.

The hardware configuration of the present embodiment can be realized according to any of the hardware configurations of the first to fifth embodiments, and the value obtained by multiplying the gas concentration in the standard gas by the pre-correction calibration curve by a predetermined coefficient is obtained. It can be realized by holding a second correction program that corrects the calibration curve so as to be the correction amount and executing it as appropriate. Further, since the processing flow of the present embodiment is the same as the processing flow of the first embodiment described with reference to FIG. 7, the description thereof will be omitted.
<Effect of Embodiment 6>

According to the constant potential electrolytic gas sensor of the present embodiment, the calibration curve can be corrected with a correction amount according to the coefficient.

0100 Constant potential electrolytic gas sensor 0101 Control unit 0102 Variation detection unit 0103 Variation judgment unit 0104 First concentration value comparison judgment unit 0105 Second concentration value comparison judgment unit 0106 Correction unit

Claims (7)

The gas to be measured is reacted with molecules in a liquid solvent via a gas permeable film, and the gas concentration is based on a calibration curve showing the relationship between the current value and the gas concentration to be presented according to the current value generated by the generated ions. Is a constant potential electrolytic gas sensor that presents
When correcting the calibration curve with a standard gas that contains almost no gas to be measured
A variation detection unit that detects variations in the output by obtaining the output corresponding to the current value of the standard gas multiple times, and
A variation determination unit that determines whether the detected variation is within a predetermined width C for not determining an abnormality, and a variation determination unit.
Judgment by comparison with the specified value A used to judge whether the gas concentration to be presented based on the calibration curve is abnormal according to the value of the current generated by the standard gas, or whether the calibration curve should be corrected. First concentration value comparison judgment unit and
A second concentration value comparison determination unit that compares and determines the gas concentration to be presented with the specified value B used for determining an abnormality of the gas sensor, which is larger than the specified value A.
A control unit that controls the determination unit to detect the abnormality,
A correction unit that corrects the calibration curve according to the value of the current generated by the standard gas,
Constant potential electrolytic gas sensor with. The constant potential electrolytic gas sensor according to claim 1, wherein the control unit has a first operating means for operating the variation determination unit and the first concentration value comparison determination unit in this order as long as no abnormality is determined. If the judgment result in the first concentration value comparison judgment unit is abnormal or the judgment result is that the calibration curve must be corrected, the control unit operates the second concentration value comparison judgment unit next. 2. The constant potential electrolytic gas sensor according to claim 2, further comprising an operating means. The constant potential electrolysis according to claim 3, wherein the control unit has a third operating means for operating the correction unit when the determination result in the second concentration value comparison determination unit is a determination result that the gas sensor is not abnormal. Type gas sensor. The correction unit according to any one of claims 1 to 4, further comprising a first correction means for correcting the calibration curve so that the gas concentration to be presented becomes 0 according to the value of the current generated by the standard gas. Constant potential electrolytic gas sensor. Any of claims 1 to 5, wherein the correction unit has a second correction means for correcting the calibration curve so that the value obtained by multiplying the gas concentration in the standard gas by the pre-correction calibration curve by a predetermined coefficient is the correction amount. The constant potential electrolytic gas sensor according to claim 1. The constant potential electrolysis type according to claim 6, wherein the correction unit has a selection receiving means that accepts the selection of whether to perform the correction by the first correction means or the correction by the second correction means. Gas sensor.

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