KR100831589B1 - Method for extracting property of gas sensor output, and device and method for measuring gas density using it - Google Patents

Abstract

A method for extracting gas sensor output properties, and a device and a method for measuring gas density using the same are provided to explain gas sensor output properties by measuring an output voltage variation rate of a gas sensor. A method for extracting gas sensor output properties includes the steps of: determining major factors of a gas sensor(S110); determining initiation for applying load resistances of resistances(RL1~RLM) inside the gas sensor(S120); determining 'n'th load resistance(S130); extracting the maximum voltage variation rate(S140); completing a data table including the maximum voltage variation rate(S1~SN) and internal resistance(Rs) for each gas sensor(S160); obtaining property constants(a,b,d) for each load resistance(S170); and defining gas sensor output properties for evaluating performance of the gas sensor(S180).

Description

Method for Extracting Property of Gas Sensor Output, and Device and Method for Measuring Gas Density Using It}

1 is a block diagram of a system for measuring output characteristic data of a gas sensor for extracting output characteristics of a gas sensor according to a first embodiment of the present invention;

2 is a simplified configuration diagram of an electric circuit for showing a correlation between an internal resistance and an output voltage of a gas sensor according to the first embodiment of the present invention.

3 is a flowchart illustrating a method of extracting output characteristics of a gas sensor according to a first embodiment of the present invention.

4 is a graph showing a correlation between the maximum voltage change rate, the output voltage change rate, and the output voltage of the present invention;

5 is a graph showing an example for obtaining the maximum voltage change rate according to the present invention.

6 is a graph for verifying the gas sensor output characteristic data according to the first embodiment of the present invention.

7 is a block diagram of a gas concentration measuring apparatus according to the first embodiment of the present invention.

8 is a flowchart illustrating a gas concentration measuring method according to the first embodiment of the present invention.

9 is a flowchart illustrating a method of obtaining a maximum voltage change rate data of a gas sensor according to a second embodiment of the present invention.

10 is a flowchart illustrating a gas concentration measuring method according to a second embodiment of the present invention.

<Description of Symbols for Main Parts of Drawings>

10 gas sensor 11 gas sensor

12: gas chamber 20: sensor connection lead

30: load resistance measuring unit 31: load resistance (R _L )

32: Output voltage (V _L ) 40: A / D converter

100: gas sensor characteristic data measuring device

110: measurement data collection unit 120: data processing unit

130: calculated data output unit 140: data storage unit

150: key operation unit

200: gas concentration measuring device 220: gas concentration calculation control unit

230: display unit 240: memory

250: key input unit

According to the present invention, an output characteristic extraction method of a gas sensor for clearly extracting an output characteristic of the gas sensor 11 by measuring a maximum voltage variation rate S representing a maximum output voltage variation rate among the output characteristics of the gas sensor 11 is provided. and; And a gas concentration measuring apparatus and method for calculating an output voltage variation rate of the gas sensor 11, calculating a gas concentration from the maximum voltage variation rate S extracted from the calculated output voltage variation ratios, and outputting the resultant value. .

In modern society, as environmental pollution sources are increased due to continuous industrialization and urbanization, continuous research on environmental technology and continuous investment in environmental industry market are being made. In this situation, various semiconductor gas sensors have been improved to cope with various factors in order to detect and prevent harmful gases which are environmental pollution sources in advance. In addition, a performance evaluation method for the developed gas sensor and a method for estimating the gas concentration (C) from the sensed output signal data have been presented.

The performance evaluation of a semiconductor gas sensor that is commonly used includes a voltage (V _air ) or a resistance (R _air ), which is an output value before gas is injected into the gas sensor, and an output voltage (V _gas ) and a resistance (R _gas ) after the gas is injected. _gas ) or a proportional equation of resistance change (R _x ), which consists of the following relationship.

[Equation 1]

또는

또는

또는

or

or

or

[Equation 2]

또는

또는

또는

or

or

or

[Equation 3]

또는

또는

or

or

However, the conventional evaluation method, the performance of the gas sensor by a simple proportional expression of the output value (V _air , R _air ) before the gas is injected into the gas sensor and the output value (V _gas , R _gas , R _x ) after the gas is injected. In general, it was not possible to objectively evaluate the performance of the gas sensor due to the initial output value which is generally changed according to the measurement environment. In addition, in the manufacturing process of the gas sensor, as all gas sensors do not have a constant resistance value, there was a problem that the output characteristics are different for each gas sensor. That is, the output value proportional expressions before and after gas injection were expressed with various values, and thus a unified performance evaluation method could not be applied. In addition, when the measurement gas is repeatedly injected at regular intervals, the output value of the gas sensor is expressed differently every moment, and thus there is a problem that the sensitivity reproducibility, which is a main requirement of the gas sensor, is significantly reduced.

The output characteristics of the semiconductor gas sensor are determined based on the initial resistance value R _S of the gas sensor and the injected gas concentration C as main factors. However, in the conventional method, the output characteristics are the main factors R _S , C. Not as clear. Since the initial resistance value R _S is a value known at the manufacturing stage, the gas concentration C may be estimated by analyzing the electrical output signal of the gas sensor, but there is no clear definition of the output characteristic. Many difficulties occurred in estimating concentration (C).

Therefore, an object of the present invention, the output of the gas sensor to obtain the output characteristics of the gas sensor, which is defined by the internal resistance (R _S ) of the gas sensor and the injected gas concentration (C) as the main factor, the output signal of the gas sensor It is to provide a feature extraction method.

Another object of the present invention is to provide a gas concentration measuring apparatus and a method for accurately measuring gas concentration using the gas sensor output characteristic relationship defined above.

The present invention to achieve the above object,

Measuring respective internal resistance values (R _S ) for the plurality of gas sensors (11), and designating load resistance (31) values connected to the plurality of gas sensors (11); Standard gas for measuring having different concentrations (C ₁ ~ C _N ) is sequentially injected, and the rate of change of the output voltage 32 measured for each gas sensor 11 is calculated for each standard gas for a predetermined time, Extracting a maximum voltage variation ratio S ₁ to S _N for each standard gas representing a maximum value among the variation ratios calculated during each gas sensor 11; By using the maximum voltage change rate (S ₁ ~ S _N ) for each gas sensor 11 retrieved, the internal resistance value (R _S ) for each gas sensor 11 measured, and the concentration of standard gas (C ₁ ~ C _N ). Defining a characteristic relationship of the maximum voltage fluctuation rate (S) expressed by the gas concentration (C) and the gas sensor 11 internal resistance value (R _S );

A gas concentration measuring apparatus (200) comprising one gas sensor (11), comprising: injecting a gas to be measured; Measuring the output voltage 32 across the load resistance 31 changed by the gas sensor 11 for a predetermined time; Calculating a voltage variation rate of the output voltage (32) during the predetermined time period; Extracting a maximum voltage change rate S representing a maximum value among the voltage change rates calculated during the predetermined time; Calculating a concentration (C) from a characteristic relation defined in the characteristic data acquisition process of the gas sensor; Comprising a gas concentration measurement process comprising; outputting the calculated gas concentration (C).

Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention will be described to be easily carried out by those of ordinary skill in the art. In the accompanying drawings, it should be noted that the same reference numerals as shown in the configuration and action, the same reference numerals are used as much as possible when indicating the same configuration or action in the other drawings. In addition, in describing the present invention below, when it is determined that a detailed description of a related known function or known configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

1 is a block diagram of a system for measuring output characteristic data of a gas sensor for obtaining an output characteristic relationship of a gas sensor 11 according to an exemplary embodiment of the present invention.

The output characteristic data measuring system of the gas sensor 11 with reference to FIG. 1 includes a gas chamber 12 temporarily storing gas for sensing gas, a gas injection device for injecting gas into the gas chamber 12, A gas sensor unit 10 including a plurality of semiconductor gas sensors 11 installed in the gas chamber 12; A sensor connection lead 20 drawn out from the gas sensors 11 and connected to the outside; The gas sensor characteristic data measuring apparatus 100 measures the characteristic data of the gas sensor by reading and calculating the signal of the gas sensor 11 transmitted through the sensor connection lead 20.

The gas sensor characteristic data measuring apparatus 100 may include a load resistor 31 connected in series to the internal resistances R _{S of} the gas sensors 11 through the sensor connection lead 20. A load resistance measuring unit 30 measuring the output voltage 32 across the resistor 31; An A / D converter 40 for sampling the measured analog output voltage 32 signal and converting the measured analog output voltage 32 signal into digital output voltage 32 data; A measurement data collection unit (110) for collecting the output voltage (32) data during a period in which gas is injected; The output voltage variation ratio is calculated from the data of the collected output voltage 32, and the maximum voltage variation ratio S, which is the maximum value, is extracted from the calculated output voltage variation ratio, and the extracted maximum voltage variation ratio S and the injected gas concentration ( A data processor 120 for acquiring characteristic constants (a, b, d) for completing the output relational expression formed by the correlation between C) and the negative resistance R _{S in the} gas sensor; A calculation data output unit 130 for outputting the output voltage 32 data, an output voltage variation rate, a maximum voltage variation rate S, and characteristic constants a, b, and d; A key manipulation unit 150 for inputting a control input signal in the process of designating the load resistor 31 and acquiring the characteristic constants (a, b, d) of the output relation equation; The data storage unit 140 for storing the output voltage 32 data, the load resistor 31, and characteristic constants a, b, and d; And a power supply unit 160 for supplying power to the characteristic data measuring apparatus 100.

FIG. 2 is a simplified configuration diagram of an electric circuit for showing a correlation between the internal resistance R _{S of the} gas sensor 11 and the output voltage 32 in the system configuration of FIG. 1.

Referring to FIG. 2, a gas sensor 11 and a load resistance measuring unit installed in the gas chamber 12 of the gas sensor unit 10 are provided in the + power source 1 and the − power source 2 of the power supply unit 160. Load resistors R _L and 31 installed at 30 are connected in series, and the output voltages V _L and 32 at both ends of the load resistors R _L and 31 are measured by the load resistance measuring unit 30. And is transferred to the A / D conversion unit 40. The gas sensor 11 has an intrinsic internal resistance value R _{S which} is a resistance value before gas is injected.

1 and 2, the characteristic relational expression of the gas sensor applied in the data processing unit 120 is as follows.

[Equation 4]

In the above characteristic relation, a, b and d are characteristic constants, S is the maximum voltage variation rate, C is the concentration of gas, and R _S is the internal resistance of the gas sensor 11.

Referring to Equation 4, the characteristic constant (a, b, d) is the input signal of the gas sensor internal resistance value (R _S ), which is measured and known, and the gas concentration (C), which knows its concentration as a standard gas. The maximum voltage fluctuation rate S calculated and extracted from the output voltage (V _L , 32) data is determined as an output signal. Accordingly, a plurality of gas sensor internal resistance values R _S , a plurality of gas concentration data C corresponding to each of the gas sensor internal resistance values R _S , and the gas sensor internal resistance values R _S. The characteristic constants (a, b, d) are determined only if there is data of the maximum voltage variation (S) consisting of the combination of the? And the gas concentration C. Preferably, a plurality of gas sensors 11 having different internal resistance values R _S are installed in the gas chamber 12, and gases having different concentrations are sequentially injected into the gas chamber 12, Maximum voltage variation (S) data can be obtained.

Since the gas chamber 12 and the gas injection device included in the gas sensor unit 10 may be implemented as a batch-type reactor or a continuous-type reactor, which are generally used, Detailed description will be omitted. In addition, since the gas injection device, the gas sensor, and the heater of the gas sensor 11 are well-known techniques, they are omitted in the present description.

FIG. 3 is a flowchart illustrating a method of extracting output characteristics of the gas sensor 11 using the system of FIG. 1.

The output characteristic extraction method of the gas sensor 11 according to FIG.

Measuring and storing respective internal resistance values R _S of the plurality of gas sensors 11; Select N standard gas concentration values (C ₁ to C _N ) to be used to obtain the output characteristics of the gas sensor (11), store the order of injection according to the serial number (n), and store M load resistance values (R) to be used. Selecting _L1 ~ R _LM ) and setting and storing according to the serial number (n) (S112); Gas sensor main factor designation step (S110) consisting of;

An initialization specifying step S120 for sequentially applying load resistances of the resistance values R _L1 to R _LM ;

designating an m th load resistance R _Lm (S130);

An initialization designation step S141 for sequentially applying a standard gas having a concentration value C ₁ to C _N ; injecting the n-th standard gas into the gas chamber 12 (S142); The process of converting and storing the output voltage 32 of each gas sensor 11 into digital data is determined in consideration of the reaction time of the gas sensor 11 to obtain sufficient output characteristics for the injected standard gas. Repeating for a time (S143); Calculating a variation rate of the output voltage 32 during the time for each gas sensor 11 (S144); Extracting the maximum voltage change rate (S _n ) for each standard gas representing a maximum value among the calculated output voltage 32 change rates, and storing the maximum voltage change rate (S _n ) extracted for each gas sensor (11) (S145). )Wow; If the injected n-th standard gas is not the last (N), the step (S142) of injecting the next standard gas is repeated, and if the maximum voltage variation ratio (S ₁ to S _N ) for all prepared standard gases is found, then Obtaining the maximum voltage fluctuation rate (S ₁ ~ S _N ) including the step S146 and S147;

If the specified mth load resistance (R _Lm ) is not the last (M), the next load resistance (R _{Lm +1} ) is designated to execute the maximum voltage variation ratio (S ₁ to S _N ) acquisition step (S140), and the specified m If the first load resistance (R _Lm ) is the last (M), the process proceeds to the next step (S150, S151);

Maximum voltage fluctuation rate (S ₁ ~ S _N ) for each gas sensor (11) obtained by load resistance (R _L1 ~ R _LM ) and concentration of standard gas (C ₁ ~ C _N ), and internal by gas sensor (11) Completing and arranging the resistance value R _S into a data table (S160);

Gas concentration (C ₁ ~ C _N ) arranged by load resistance (R _L1 ~ R _LM ), gas sensor internal resistance value (R _S ), gas concentration (C ₁ ~ C _N ) and gas sensor internal resistance value (R _S) the maximum voltage change rate, using an (S ₁ ~ S _N), the maximum voltage change value (S) is expressed as the gas concentration (C) and the gas sensor 11, internal resistance (R _S) corresponding to Obtaining the characteristic constants (a, b, d) for each of the load resistances R _L1 to R _LM in the characteristic relation equation (Equation 4) of S170;

Using the data table of the step (S160) and the characteristic constants (a, b, d) of each of the load resistances (R _L1 to R _LM ) of the step (S170), it is defined as the output characteristics of the gas sensor, and the performance is evaluated. And using the gas concentration measuring apparatus (S180).

Since the maximum voltage variation ratio S ₁ to S _N obtained in the step S140 is selected as the maximum value among the variation ratios of the output voltage V _L , the maximum voltage variation ratio S ₁ to S _N is constant even in repeated measurement regardless of the unstable initial output voltage V _L. Has a value. Therefore, while the conventional Equations 1, 2 or 3, which are affected by the initial output value, do not exhibit the exact output characteristics of the gas sensor, the maximum voltage variation ratio S according to the present invention is determined by the initial output voltage (S). V _L ) accurately represents the electrical output characteristics of the gas sensor.

Table 1 below is a data table measured by three gas sensors by injecting hydrogen sulfide (H ₂ S), Table 2 is to complete the characteristic relationship (Equation 4) using the measured data table of Table 1.

TABLE 1

Gas sensor Internal resistance (R _S , ㏁) Load resistance (R _L , k) Gas concentration (C, ppm) Maximum Voltage Fluctuation Rate (S)     Sensor 1 (S-A1)     7.82  10 3 0.78 6 1.34 12 2.98 18 4.31  30 3 1.60 6 1.87 12 2.66 18 3.36  60 3 1.32 6 1.77 12 2.35 18 2.76      Sensor 2 (S-A2)      15.75  10 3 2.00 6 4.64 12 11.74 18 19.42  30 3 4.56 6 9.82 12 19.63 18 29.58  60 3 4.78 6 9.10 12 16.84 18 23.38      Sensor 3 (S-A3)      9.56  10 3 0.74 6 1.58 12 3.85 18 5.44  30 3 1.63 6 2.18 12 4.03 18 4.32  60 3 1.63 6 1.94 12 2.93 18 3.67

TABLE 2

Load resistance (R _L , k) Characteristics relation Coefficient of determination (r ² )  10

 0.988  30

 0.997  60

 0.997

The characteristic relations in Table 2 are the results obtained by applying the data in Table 1 to commonly used multiple regression methods.

4 is a graph showing the relationship between the output voltage V _L , 32, the output voltage variation rate, and the maximum voltage variation rate S. FIG. In the graph on the left, the gas is injected into the gas chamber 12 in a batch reactor (upper graph) and a continuous reactor (lower graph), and the outputs of both ends of the load resistors R _L and 31 provided in the load resistance measuring unit 30 are output. The value obtained by measuring the change in voltage (V _L , 32) during the gas injection time (T) is shown. The graph on the right shows the rate of change of the output voltage obtained by calculating the slope on the graph of the measured output voltages V _L and 32. At this time, the maximum value of the output voltage change rate in the graph on the right represents the maximum voltage change rate (S).

5, the load resistance (R _L , 31) of the load resistance measuring unit 30 is specified as 10 kΩ, and injected into a batch reactor of hydrogen sulfide (H ₂ S) of 6ppm concentration measured by the output voltage (V _L , 32) and a graph showing the output voltage change rate and the maximum voltage change rate S calculated based on the output voltages V _L and 32. Referring to FIG. 5, it can be seen that the rate of change of the output voltage indicating the rate at which the gas sensor 11 reacts after the gas is injected increases rapidly during the initial predetermined time, and the maximum rate of change of voltage S is also present at this time. .

Figure 6 is a graph showing the verification results of the characteristic relationship obtained from the results of Table 1 and Table 2. The horizontal axis of FIG. 6 represents the concentration value of the actual gas injected, and the vertical axis represents the concentration value estimated by inverse calculation by substituting the maximum voltage fluctuation rate S and the gas sensor internal resistance R _S in the characteristic relationship equation of Table 2. . According to FIG. 6, it can be seen that the concentration obtained by substituting the measured maximum voltage variation ratio S and the gas sensor internal resistance R _S into a characteristic relation equation is estimated as a slight error of the concentration of the gas actually injected. Therefore, the characteristic relationship of the present invention clearly explains the internal resistance R _S and the injected gas concentration C information of the gas sensor which directly affect the performance of the gas sensor. In addition, since the maximum voltage variation (S) of the gas sensor accurately expresses the electrical output characteristics of the gas sensor, the performance evaluation of the gas sensor can also be made accurately regardless of other factors.

7 is a block diagram of a gas concentration measuring apparatus utilizing characteristic data of the gas sensor 11 obtained by FIGS. 1 and 3 according to the first embodiment of the present invention.

The gas concentration measuring apparatus of FIG. 7 includes a gas chamber 12 temporarily storing gas for sensing gas, a gas injection apparatus for injecting gas into the gas chamber 12, and a gas chamber 12. A gas sensor unit 10 including a plurality of semiconductor gas sensors 11 installed; A load resistance measuring unit (30) having a load resistor (31) connected in series with the gas sensor (11), and measuring an output voltage (32) at both ends of the load resistor (31); The value of the load resistance 31, the characteristic constant (a, b, d) value determined according to the load resistance 31, the internal resistance value (R _S ) of the gas sensor 11, and the characteristic relationship equation (Equation 4 A memory 240 for storing information about and storing measured data; An A / D converter 40 for sampling the measured analog output voltage 32 signal and converting the measured analog output voltage 32 signal into digital output voltage 32 data; The output voltage fluctuation rate is calculated from the measured output voltage 32 data, and the maximum voltage fluctuation rate S which is the maximum value among the calculated output voltage fluctuation rates is searched out and stored in the maximum voltage fluctuation rate S and the memory 240. A gas concentration calculating control unit 220 for calculating the injected gas concentration C by substituting the internal resistance value R _S and the characteristic constants a, b, and d into the characteristic relation equation (Equation 4); A display unit 230 for outputting the calculated gas concentration C; And a key input unit 250 for injecting a gas and receiving a signal for controlling the gas concentration calculating control unit 220.

8 is a flowchart illustrating a gas concentration measuring method for measuring the concentration of gas in the configuration of FIG. 7 according to the first embodiment of the present invention.

8, the gas concentration measuring method includes injecting a gas to be measured into the gas sensor unit 10 (S210); Measuring the output voltage V _L across the load resistor R _L and converting it into digital data (S220); Calculating a rate of change of the measured output voltage (V _L ) (S230); Extracting a maximum voltage change rate S representing a maximum value among the output voltage change rates calculated while the gas is injected (S240); The gas concentration injected from the maximum voltage variation ratio S, the internal resistance value R _S stored in the memory 240 and the characteristic constants (a, b, d) by using a characteristic relation equation (Equation 4) Calculating S) (S250); And outputting the calculated gas concentration C to the display unit 230 (S260).

The internal resistance value R _S stored in the memory 240 of FIG. 7, the characteristic constants a, b, d and the load resistance R _L are the gas sensors 11 installed in the gas sensor unit 10. It is data indicating the characteristics of, and obtained in the gas sensor 11 output characteristic data measuring method of FIG. In addition, in step S250 of FIG. 7, the internal resistance value R _S and the characteristic constants (a, b, d) are used as fixed constants of the characteristic relation (Equation 4).

9 is a flowchart illustrating a method of acquiring a maximum voltage variation (S) data of a gas sensor according to a second embodiment of the present invention.

The method for acquiring the maximum voltage variation (S) data of the gas sensor of FIG. 9 may be performed using the configuration of FIG. 1, and thus a detailed description thereof will be omitted. However, the data processing unit 120 does not perform a calculation process for obtaining the characteristic constants (a, b, d), and matches the extracted maximum voltage variation ratio (S) with the concentration of the standard gas (C). 140).

In the method for acquiring the maximum voltage variation (S) data of the gas sensor according to FIG. 9, the concentration value C ₁ to C _N of the standard gas to be used for data acquisition is stored, and the load resistance value R _L is designated and stored. Step (S310); Assigning a serial number n to the standard gas, and initializing the serial number n to 1 (S321); injecting the nth standard gas into the gas chamber 12 (S322); The process of measuring the output voltage 32, converting it into digital data, and storing the same is repeated for a time determined in consideration of the reaction time of the gas sensor 11 to obtain sufficient output characteristics for the injected standard gas (S323). )Wow; Calculating a change rate of the output voltage 32 during the time period and extracting a maximum voltage change rate S _{n for each} standard gas representing a maximum value among the calculated output voltage 32 change rates (S324); Storing the extracted maximum voltage change rate (S _n ) (S325); If the injected n-th standard gas is not the last (N), the step (S322) of injecting the next standard gas is repeated, and when the maximum voltage variation ratio (S ₁ to S _N ) for all prepared standard gases is found, Step S326, S327 to go to step; And a step S330 of completing the data table of the maximum voltage variation ratios S ₁ -S _N corresponding to the concentration values C ₁ -C _N of the standard gas.

The data table completed in S330 is utilized for a gas concentration measuring apparatus using the gas sensor 11.

Since the load resistance value R _L specified in the step S310 changes the value of the maximum voltage variation ratio S ₁ to S _N in accordance with the value, the load resistance value R _L used in the gas concentration measuring apparatus. Should be set equal to If a plurality of load resistance values R _L are specified in the gas concentration measuring apparatus, the corresponding maximum voltage variation ratios S ₁ to S _N must be obtained.

10 is a flowchart illustrating a gas concentration measuring method according to a second embodiment of the present invention. The gas concentration measuring method of FIG. 10 may be performed using the configuration of FIG. 7, and thus detailed description thereof will be omitted. However, the gas concentration calculation control unit 220 does not use the characteristic relation equation (Equation 4), but the maximum voltage variation ratio S ₁ to S _N corresponding to the concentration values C ₁ to C _N stored in the memory 240. Data table).

Gas concentration measuring method according to Figure 10, the step of injecting the gas to be measured in the gas sensor unit 10 (S410); The load resistance (R _L) step (S420) of measuring an output voltage (V _L) of both ends, and converted into digital data; Calculating a rate of change of the measured output voltage (V _L ) (S430); Extracting a maximum voltage change rate S representing a maximum value among the output voltage change rates calculated while the gas is injected (S440); Checking whether the extracted maximum voltage change rate (S) is in a data table stored in the memory 240 (S450); If the maximum voltage variation ratio (S) is present in the data table in step S450, reading a gas concentration C value corresponding thereto (S461); If the maximum voltage change rate (S) is not present in the data table in the step S450, the maximum voltage change rate value and the gas concentration value before and after the maximum voltage change rate S are respectively read (S460). Calculating a gas concentration (C) corresponding to the maximum voltage change rate (S) by interpolation using data (S470); And (S480) outputting the gas concentration (C) obtained in the (S461) or the (S470).

The interpolation method used in the step (S470), when there is no desired value in the data table stored in the memory 240, by using the data before and after the closest among the stored data, the maximum voltage change rate ( As a method of estimating the gas concentration (C) value corresponding to the S) value, it can be applied by a general known numerical method.

Although illustrated and described in the specific embodiments to illustrate the technical spirit of the present invention, the present invention is not limited to the same configuration and operation as the specific embodiment as described above, within the limits that various modifications do not depart from the scope of the invention It can be carried out in. Therefore, such modifications should also be regarded as belonging to the scope of the present invention, and the scope of the present invention should be determined by the claims below.

Therefore, as described above, the present invention measures the gas sensor output voltage variation rate, which is based on the internal resistance R _S of the gas sensor and the injected gas concentration C, to objectively clarify the output characteristics of the gas sensor. Can be explained.

In addition, the present invention can explain the output characteristics of the gas sensor, regardless of the variable initial output value of the gas sensor.

In addition, the present invention can be usefully used for accurate gas sensor performance evaluation by measuring the rate of change of the output voltage including the main information of the gas sensor and independent of the initial output value.

Further, the present invention can accurately measure the gas concentration by using the output characteristics described by the internal resistance R _S and the gas concentration C of the gas sensor.

Claims (10)

A gas sensor unit 10 including a gas sensor 11 and a gas chamber 12; Measuring the output voltage (V _L ) across the load resistor (R _L , 31) connected in series with the gas sensor 11, calculates the temporal variation rate of the output voltage (V _L ), the calculated output voltage variation rate In the method for extracting the output characteristic of the gas sensor 11 by using; gas sensor characteristic data measuring apparatus 100 to obtain the maximum voltage variation (S) by extracting the maximum value among the Injecting gas for a predetermined time (S142); Measuring an output voltage V _L which varies during a time in which gas is injected (S143); Calculating a temporal variation rate of the output voltage (S144); Extracting a maximum voltage change rate S, which is a maximum value, among the calculated output voltage change rates (S145); Extraction method of output characteristics of the gas sensor consisting of. The method of claim 1, Measuring internal resistance (R _S ) for the plurality of gas sensors (S111); Sequentially injecting a plurality of standard gases having different concentrations into the plurality of gas sensors, and repeating the obtaining of the maximum voltage variation rate (S142, S143, S144, S145) (S140); By using the maximum voltage change rate data obtained in the step S140, the plurality of gas sensor internal resistance data, and the plurality of standard gas concentration data, a gas concentration C and a gas sensor internal resistance R _S. Obtaining a characteristic relationship expression of the maximum voltage change rate S expressed (S170); Output characteristics extraction method of the gas sensor further comprises. The method of claim 2, The characteristic relation is

And a characteristic constant (a, b, d) of the equation is determined in step (S170). The method of claim 3, wherein The characteristic constants (a, b, d) of the characteristic relation expression are Method for extracting output characteristics of a gas sensor, characterized in that it is calculated differently according to the size of the load resistance (R _L , 31). In the gas concentration measuring apparatus for calculating the gas concentration by extracting the maximum voltage change rate (S) that is the maximum value among the output voltage (V _L ) change rate of both ends of the load resistance (R _L ) connected to the gas sensor 11, A gas sensor unit including a gas chamber 12 into which gas is injected, a gas injection device for injecting gas into the gas chamber 12, and a gas sensor 11 installed in the gas chamber 12 ( 10); A load resistance measuring unit (30) having a load resistor (31) connected in series with the gas sensor (11) and measuring an output voltage (32) across the load resistor (31); Storing the characteristic constant value for the characteristic relation equation of the gas sensor 11 determined by the load resistance 31 value, the gas sensor 11 internal resistance value R _S , and the load resistance 31. A memory 240; An A / D converter 40 for sampling the measured analog output voltage 32 signal and converting the signal into digital output voltage data; The output voltage fluctuation rate is calculated from the digital output voltage data, the maximum voltage fluctuation rate S which is the maximum value is calculated from the calculated output voltage fluctuation rate, and the maximum voltage fluctuation rate S and the internal resistance value R _{S are} calculated. A gas concentration calculating control unit 220 for calculating the injected gas concentration C by substituting the characteristic relational expression; A display unit 230 for outputting the calculated gas concentration C; And a key input unit (250) for injecting gas and inputting a signal for controlling the gas concentration calculating control unit (220). The method of claim 5, The characteristic relation is

In the above equation, the characteristic constants (a, b, d) measure the maximum voltage fluctuation rate (S) which varies according to different gas sensor (11) internal resistance (R _S ) and different gas concentration (C). The gas concentration measuring device, characterized in that predefined in the data obtained by. As the value of the internal resistance R _S of the gas sensor 11 reacting to the injected gas changes, the output voltage 32 of both ends of the load resistance connected in series with the gas sensor 11 is measured, thereby measuring the gas concentration ( In the gas concentration measuring method for calculating C), Injecting a gas to be measured for a predetermined time (S210); Measuring the output voltage 32 that varies during the time of gas injection (S220); Calculating a temporal variation rate of the output voltage 32 (S230); Extracting a maximum voltage change rate S, which is a maximum value, among the calculated output voltage change rates (S240); The maximum voltage fluctuation rate (S), the internal resistance of the gas sensor (R _S ), and the characteristic constant (a, b) are derived from the characteristic relation equation derived through the output characteristic extraction method of the gas sensor of any one of claims 2 to 4. calculating the gas concentration C by substituting the d) value (S250); Outputting the calculated gas concentration C (S260); Gas concentration measurement method comprising a. The method of claim 7, wherein The characteristic relation is

The constants (a, b, d) of the above equations are measured for the maximum voltage fluctuation rate (S) which varies according to different gas sensor (11) internal resistance (R _S ) and different gas concentration (C). Gas concentration measurement method, characterized in that predefined in the data obtained by. Using a data table made up of respective maximum voltage variation (S) values corresponding to a plurality of different gas concentrations (C), the internal resistance (R _S ) of the gas sensor 11 in response to the injected gas is In the gas concentration measuring method for calculating the gas concentration (C) by measuring the output voltage 32 across the load resistance connected in series with the gas sensor 11, Injecting a gas to be measured for a predetermined time (S410); Measuring the output voltage 32 during the gas injection time (S420); Calculating a temporal variation rate of the output voltage 32 (S430); Extracting a maximum voltage change rate S, which is a maximum value, among the calculated output voltage change rates (S440); Checking whether or not a value of the extracted maximum voltage change rate (S) is included in the maximum voltage change rate (S) data table (S450); In step S450, if the value of the extracted maximum voltage change rate S is included in the maximum voltage change rate S table, calling a gas concentration C value corresponding thereto (461); Outputting the called gas concentration C value (S480); Gas concentration measurement method comprising a. The method of claim 9, In the step (S450), if the value of the extracted maximum voltage change rate (S) is not included in the maximum voltage change rate (S) data table, Calling up the maximum voltage change rate value and the gas concentration value before and after the maximum voltage change rate (S) (S460); Calculating a gas concentration (C) corresponding to the maximum voltage change rate (S) by interpolation using the called data (S470); Gas concentration measurement method further comprises.

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