JP2001083086A - Gas concentration measuring method and gas concentration measuring device - Google Patents

Abstract

(57) [Problem] To provide a high-accuracy infrared absorption-type gas concentration measurement immediately without performing warm-up operation or calibration using a reference gas. SOLUTION: The amount of detected infrared rays obtained by a measuring cell 11A to which a sample gas is introduced and irradiated from a light source 41 with infrared rays, and the measuring cell 11B to which the sample gas is introduced and not irradiated with infrared rays
By taking the difference from the detected infrared ray amount obtained by the above, the infrared ray component transmitted through the sample gas not including the radiation component from each part is obtained, and the compensation gas is obtained by the compensation cell 12A in which the comparison gas is introduced and the light source 42 emits the infrared ray. The difference between the detected infrared ray amount and the detected infrared ray amount obtained by the compensation cell 12B into which the comparison gas is introduced and not irradiated with the infrared ray is taken, and the transmission window 21A,
The influence of the gas and the temperature of each part of the apparatus is avoided by obtaining an infrared component exhibiting the absorption characteristic of 22A and calculating the gas concentration from both infrared components.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a gas concentration measuring method and a gas concentration measuring device.

[0002]

2. Description of the Related Art Infrared absorption type gas concentration measurement technology is to continuously measure the concentration of a specific component gas (detection gas) in a sample gas using an infrared absorption effect inherent to gas molecules. The concentration measuring device closes the cylindrical cell with a transmission window, irradiates infrared light from the light source into the cell with the sample gas introduced into the cell, and transmits the transmitted infrared light emitted from the other light transmission window on the emission side. The light is received by a detector arranged behind the transmission window. The amount of detected infrared light decreases in accordance with the concentration of the detection gas, and the general expression representing the transmitted light amount i after the light having the initial light amount i ₀ has passed through the distance L in the sample gas containing the detection gas having the concentration C is represented by the following equation ( It is represented by 1). In the equation, K is an absorption coefficient specific to the detection gas. _{i = i 0 · exp (-K} · C · L) ··· (1)

The infrared gas analyzer described on page 271 of Sensor Engineering (1982) has a cell (compensation cell) equivalent to a cell (measurement cell) into which a sample gas is introduced, and a comparative gas having no infrared absorption. A certain inert gas (N _2, etc.) is charged, and the amount of infrared rays is also detected for the compensation cell, and the concentration of the detected gas is determined by calculating the difference between the amount of infrared rays detected by the measurement cell and the amount of infrared rays detected by the compensation cell. ing.

FIG. 6 is a schematic diagram showing the structure of the infrared gas analyzer. The compensation cell 91B is affected by infrared rays radiated from the cell 91B and infrared rays radiated from the transmission window 92B. infrared rays radiated from the cell 91A, infrared rays radiated from the transmission window 92A, infrared rays radiated from the sample gas, the influence of infrared rays radiated from the interference gas, detected amount of infrared rays I _a of the compensation cell, the detection of the measuring cell infrared quantity I _B by the following equation (2) is represented by (3). In the figures and _equations , I ₀ is the light source 94A, 94B
Amount of infrared radiated from, I ₁ is the cell 91A, the amount of infrared rays radiated from 91B, I ₂ is the transmission window 92A, the amount of infrared rays radiated from 92B, I ₃ infrared quantity radiated from the detector gas, I ₄ Is the amount of infrared radiation radiated from the interference gas, α
The transmission window 92A, the absorption coefficient of 92B, L ₁ is the cell 91
A, the length of 91B, L ₂ is the transmission window 92A, the thickness of the 92B, the absorption coefficient of mu ₁ is detected gas, C ₁ is the concentration of the detection gas, mu ₂ is an absorption coefficient of the interference gas, C ₂ is the interference gas Represents the concentration of _{I A = {I 0 + I} 1} · exp (-α · L 2) + I 2 ··· (2) I B = [I 0 · exp {- (μ 1 · C 1 + μ 2 · C 2) · L ₁ ｝ + I ₁ + C ₁ · I ₃ + C ₂ · I ₄ ] · exp (−α · L ₂ ) + I ₂ (3)

[0005] The difference I _B -I _A detection amount of infrared rays and measuring the cell 91A and the compensation cell 91B becomes the following equation. _{I B -I A = [I 0} · exp {- (μ 1 · C 1 + μ 2 · C 2) · L 1} -I 0] + (C 1 · I 3 + C 2 · I 4)] · exp ( −α · L ₂ ) (4)

In order to determine the concentration C ₁ of the detected gas in the equation (4), the amount of infrared light I ₀ radiated from the light sources 94A and 94B is fixed, and the temperatures of the transmission windows 92A and 92B, the temperature of the sample gas and it is necessary to be constant each radiation amount of the formula keeping the pressure constant, after a predetermined warm-up operation, to perform calibration with a known concentration of the reference gas, to measure the I _a, I _B. The influence of interference gas (μ ₂ · C ₂ , C ₂ · I
₄ ) can be eliminated by a filter.

[0007]

However, the infrared gas analyzer requires a long time for warm-up operation and calibration, so that the measurement efficiency is not always good. In addition, depending on the application, it is difficult to apply, for example, as an in-vehicle sensor that does not require time for warm-up operation and calibration.

[0008] The present invention has been made in view of the above circumstances,
An object of the present invention is to provide an infrared absorption type gas concentration measurement method and a gas concentration measurement device that do not require warm-up operation or calibration.

[0009]

According to the first aspect of the present invention, in the gas concentration measuring method, a sample gas is introduced from two types of cells having different introduced gases in a state where the amount of infrared radiation emitted from a light source is large. A first detection procedure for obtaining the amount of infrared light detected by the measurement cell and a second detection procedure for obtaining the amount of infrared light detected by the measurement cell in a state where the amount of infrared light emitted from the light source is small are performed. A third detection procedure for obtaining the amount of infrared rays detected in the compensation cell into which the comparison gas is introduced out of the above two types of cells in a large state, and the detection infrared ray amount in the compensation cell in a state where the amount of infrared rays emitted from the light source is small And a fourth detection procedure to obtain. Next, the difference between the detected infrared ray amount in the first detection procedure and the detected infrared ray quantity in the second detection procedure and the difference between the detected infrared ray quantity in the third detection procedure and the detected infrared ray quantity in the fourth detection procedure are measured. For each of the cell and the compensation cell, only the transmitted component of infrared light from the light source is obtained. Next, the concentration of the component gas is calculated based on the two transmission components.

By taking the difference between the detected infrared ray amount when the irradiation infrared ray amount is large and the detection infrared ray amount when the irradiation infrared ray amount is small, the radiation component from each part is canceled out, and the transmission component of the infrared ray from the light source is obtained. The transmitted component of infrared light from this light source is obtained for the sample gas and for the comparative gas, and the only difference is the amount of infrared absorption in the gas introduced into the cell.
The detection gas concentration can be obtained without being affected by the fluctuation of the irradiation infrared ray amount of the light source and the fluctuation of the infrared absorption in the transmission window.

According to the second aspect of the present invention, the gas concentration measuring device used in the gas concentration measuring method is configured as follows. First and second measurement cells are provided as the measurement cells, and first and second compensation cells are provided as the compensation cells. The light source is configured to irradiate infrared light more strongly to the first measurement cell than to the second measurement cell, and to irradiate infrared light more strongly to the first compensation cell than to the second compensation cell. The amount of infrared light detected in the first detection procedure is obtained by a first measurement cell, the amount of infrared light detected in the second detection procedure is obtained by a second measurement cell, and the amount of infrared light detected in the third detection procedure is obtained by a second measurement cell. One compensation cell is used, and the amount of infrared rays detected in the fourth detection procedure is obtained by the second compensation cell.

By providing four cells so that the amount of infrared rays detected in the first to fourth detection procedures can be obtained immediately, it is hardly affected by fluctuations in the amount of radiation from the cells. And the time required for measurement can be shortened.

According to the third aspect of the present invention, the light source comprises only the light source for the first measurement cell and the light source for the first compensation cell.

The second measurement cell and the second compensation cell are not irradiated with infrared rays, so that the first measurement cell and the first compensation cell are not irradiated.
Since the irradiation infrared ray amount is different between the compensation cell described above and the second measurement cell and the second compensation cell, it is not necessary to provide a light source for each cell, and the configuration can be simplified.

According to a fourth aspect of the present invention, a gas concentration measuring device used in the gas concentration measuring method is configured as follows. The measurement cell and the compensation cell are provided one by one. The light source is configured so that the amount of irradiation infrared light can be freely switched. In addition, a capturing means for capturing the detection output of the detector in synchronization with the switching of the irradiation infrared ray amount is provided. The amount of infrared rays detected in the first detection procedure is set as a detection output by the measurement cell when the amount of irradiation infrared rays is large, and the amount of infrared rays detected in the second detection procedure is detected by the measurement cell when the amount of irradiation infrared rays is small. The amount of infrared rays detected in the third detection procedure is used as the detection output by the compensation cell when the amount of irradiation infrared rays is large, and the amount of infrared rays detected in the fourth detection procedure is calculated by the compensation cell when the amount of irradiation infrared rays is small. This is the detection output.

Since the detection output of the detector is taken in synchronism with the switching of the irradiation infrared ray amount of the light source, the detection infrared ray quantity of the first and second detection procedures can be obtained by a single measuring cell. The amount of infrared rays detected in the third and fourth detection procedures can be obtained by one compensation cell, and the apparatus can be made compact.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) FIG. 1 shows a configuration of a gas concentration measuring device for explaining a first embodiment of the present invention. The infrared absorption type gas concentration measuring device comprises four substantially identical cylindrical cells 11A, 11B, 12A,
12B are arranged in parallel, and one end of each of the cells 11A to 12B has a transmission window 2 that can transmit infrared rays in the absorption wavelength range of the detection gas.
It is closed by 1A, 21B, 22A, 22B. Peripheral walls 111A, 111B, 1 of cells 11A to 12B
21A and 121B are made of, for example, stainless steel whose inner peripheral surface is polished, and the transmission windows 21A to 22B are made of, for example, calcium fluoride. Each cell 11A-1
2B, a cell 11A is provided behind the transmission windows 21A to 22B.
Optical sensors 31A, 31B, which are detectors for detecting infrared rays emitted from the transmission windows 21A to 22B on the axis of the light beams 12A to 12B.
32A and 32B are provided. Optical sensors 31A-32B
Various types such as a thermopile sensor can be used, and it is preferable to select the type in consideration of the application such as responsiveness.

Common heater blocks 61 and 62 are arranged evenly at two locations in the longitudinal direction of the cells 11A to 12B in a direction intersecting the cells 11A to 12B so that the cells 11A to 12B are kept warm. It has become. The cell temperature is maintained at, for example, 80 ° C. by the heater blocks 61 and 62.

A sample gas for measurement is introduced into two cells (hereinafter, referred to as measurement cells) 11A and 11B of the four cells 11A to 12B through a gas preheating passage 100. . The gas preheating path 100 is kept warm by the heater blocks 61 and 62, and preheats the sample gas introduced into the measurement cells 11A and 11B.
The inflow of the low-temperature sample gas prevents dew condensation on the cell walls and the like. The temperature of the sample gas introduced into the measurement cells 11A and 11B is checked by the gas temperature sensor 71.

The remaining two cells (hereinafter referred to as compensation cells as appropriate) 12A and 12B are filled with an inert gas (such as N ₂ ) having no infrared absorption.

One of the measuring cells 11A and 11B (first measuring cell) 11A and one of the compensating cells (second compensating cell) 11B have the other ends similar to the transmission windows 21A to 22B. Are closed by transmission windows 23 and 24, and light sources 41 and 42 are provided behind the transmission windows 23 and 24, respectively. Infrared rays from the light sources 41 and 42 pass through the cells 11A and 11B, and
A and 31B are irradiated.

A gas filter 5 is provided in front of the light sources 41 and 42 in the infrared irradiation direction. The gas filter 5 is filled with an interference gas (for example, CO ₂ in CO detection) whose infrared absorption wavelength is close to the detection gas.
The infrared rays having the absorption wavelength of the interference gas are previously removed from the infrared rays emitted from the light sources 1 and 42.

With this configuration, the present gas concentration measuring apparatus has a first measuring cell 11A and a first compensating cell 12A.
In this way, the amount of infrared light in a state where infrared light is radiated from the light sources 41 and 42 is obtained, and the other of the measurement cells (the second measurement cell) 1
In 1B and the other (second compensation cell) 12B of the compensation cell, the amount of infrared rays without irradiation of infrared rays from the light sources 41 and 42 can be obtained. That is, as the infrared detection procedure under the four different conditions, the light source 4 in the first measurement cell 11A is used.
A first infrared detection procedure performed in a state where there is infrared irradiation from the first, a second infrared detection procedure performed in a state where there is no infrared irradiation from the light source 41 in the second measurement cell 11B,
A third infrared detection procedure performed in the state where there is no infrared radiation from the light source 42 in the compensation cell 12A, and a fourth infrared detection procedure performed in the absence of infrared radiation from the light source 42 in the second compensation cell 12B are performed simultaneously. be able to.

FIG. 2 shows the irradiation of infrared rays from the light source and the radiation from each section. The infrared rays detected by the optical sensors 31A to 32B for the cells 11A to 12B are as follows. In the figures and equations, symbols and the like indicating the amount of radiation from the detection gas are defined in the same manner as in equations (2) and (3). (A) detecting the amount of infrared radiation of the first measurement cell _{11A: I a = {I 0} · exp (-μ 1 · C 1 · L 1) + I 1 · C 1 · I 3 + C 2 · I 4} · exp ( −α · L ₂ ) + I ₂ (5) (b) Infrared ray amount detected by the second measurement cell 11B: I _b = (I ₁ + C ₁ · I ₃ + C ₂ · I ₄ ) · exp (−α) L ₂ ) + I ₂ (6) (c) Detected infrared ray amount of first compensation cell 12A: I _c = {I ₀ + I ₁ } · exp (−α · L ₂ ) + I _2. 7) (d) Infrared ray amount detected by the second compensation cell 12B: I _d = I ₁ · exp (−α · L ₂ ) + I ₂ (8) In the equation, the term exp of the absorption of the interference gas is expressed. (−μ ₂・
C ₂ ) is not included, because it is removed by the gas filter 5.

Next, the measurement cells 11A and 11B and the compensation cell 1
Cells 1A (12A) with and without infrared irradiation from light sources 41 and 42 for each of 2A and 12B
The difference between the detected infrared ray amount and 1B (12B) (Equation (5) -Equation (6), Equation (7) -Equation (8)) is obtained. Thereby, the radiation from the walls of the cells 11A to 11B and the transmission windows 21A to 21B
Of the infrared rays emitted from the light source 41 in the first measurement cell 11A, the component of the infrared rays emitted from the light source 41 and transmitted through the sample gas in the measurement cell 11A and the transmission window 21A (formula (1)). (9)) and, among the infrared rays emitted from the light source 42 in the first compensation cell 12A, the inert gas in the compensation cell 12A and the transmission window 22A.
Is obtained (Equation (10)). _{I a -I b = I 0 ·} exp (-μ 1 · C 1 · L 1) exp (-α · L 2) ··· (9) I c -I d = I 0 · exp (-α · L ₂ ) ・ ・ ・ (10)

Finally, the ratio of the expression (9) to the expression (10) is obtained to obtain the concentration C _{1 of the} detected gas. C ₁ = (μ ₁ · L ₁ ) ^-1 ln {(I _c −I _d ) / (I _a −I _b )} (11)

[0027] Thus, the detection gas concentration in the sample gas by substituting detected amount of infrared rays I _a ~I _d obtained by four cells 11A~11B the equation (11) is obtained. Equation (11)
As is better known, changes in the amount of infrared radiation radiated from the light sources 41 and 42, changes in the amount of infrared radiation from the sample gas due to changes in the temperature and pressure of the sample gas, and changes in the amount of infrared light due to changes in the temperatures of the transmission windows 21A to 22B. By canceling out the influence of the absorption amount and the radiation amount, high-accuracy concentration measurement can be immediately performed without sufficient warm-up or calibration.

Since the equation (11) includes the absorption coefficient μ ₁ , when calculating the concentration C ₁ , the temperature and pressure of the sample gas are measured, and the absorption coefficient μ ₁ is corrected based on the measured temperature and pressure. .

When 100 ppm of CO gas using nitrogen as a carrier gas was measured as a sample gas using this apparatus, an accuracy of ± 10% was obtained immediately after the apparatus was started.

Further, operations in the case of using mounted measured gas concentration of this device on a vehicle or the like to control the vehicle, the correction and Formula absorption coefficient μ ₁ (11) is configured to perform the operation means such as a microcomputer It is good to do.

(Second Embodiment) FIG. 3 shows a configuration of a gas concentration measuring device for explaining a second embodiment of the present invention.
The gas concentration measuring device has a configuration in which cells without infrared irradiation from the light source are substantially omitted from the configuration of the first embodiment, and portions that operate substantially the same as in the first embodiment have the same numbers. A description will be given with a focus on differences from the first embodiment. The present gas concentration measuring device has a cylindrical peripheral wall 111C,
Two substantially identically shaped cells 11C having 121C,
12C are arranged in parallel, and both ends of the cells 11C and 12C are respectively provided with transmission windows 21C and 23C, 22C and 24C.
Has been closed.

A sample gas for measurement is introduced into one of the two cells 11C and 12C (measurement cell) 11C through the gas preheating passage 100.

The other cell (compensation cell) 12C is filled with an inert gas (such as N ₂ ) having no infrared absorption.

The measurement cell 11C and the compensation cell 12C include:
Optical sensors 31C and 32C are provided at one end, and light sources 41 and 42 are provided at the other end. Infrared rays from the light sources 41 and 42 irradiate the cells 11C and 12C toward the optical sensors 31C and 32C, respectively. It is supposed to be. The light sources 41 and 42 are configured to be capable of switching the amount of infrared radiation to be irradiated.
At the frequency of z, the amount of irradiated infrared rays repeats large and small.

The control section 72, which is a capturing means, is constituted by a general microcomputer or the like, and captures the detection outputs of the optical sensors 31C and 32C in synchronization with the control signals of the light sources 41 and 42. As shown in FIG. 8, the detected infrared ray amount when the irradiation infrared ray amount is large and the detected infrared ray amount when the irradiation infrared ray amount is small are output and obtained for each of the measurement cell 11C and the compensation cell 12C. ing.

According to the present gas concentration measuring device, the measuring cell 11C can obtain the amount of infrared light when the amount of infrared light from the light source 41 is large and the amount of infrared light when the amount of infrared light from the light source 41 is small. In the compensation cell 12C, the amount of infrared light when the amount of infrared radiation from the light source 42 is large and the amount of infrared light when the amount of infrared radiation is small are obtained.
That is, as the infrared detection under the four different conditions, a first infrared detection procedure performed in the measurement cell 11C in a state where infrared light is emitted from the light source 41, and a second infrared detection procedure performed in the measurement cell 11C without infrared light from the light source 42 The third infrared detection procedure performed in a state where infrared light from the light source 42 is irradiated in the compensation cell 12C, and the fourth infrared detection procedure performed in a state where no infrared light is irradiated from the light source 42 in the compensation cell 12C. Can be performed simultaneously.

FIG. 5 shows the irradiation of infrared rays from the light source and the radiation from each part. The amount of infrared rays detected by the optical sensors 31C and 32C for the cells 11C and 12C is as follows. In the figures and equations, symbols and the like indicating the amount of radiation from the detection gas are defined in the same manner as in equations (2) and (3). The amount of infrared radiation emitted from the light sources 41 and 42 is defined as I ₀₁ when it is large, and I ₀₂ when it is small. (A) detecting the amount of infrared rays measurement cell 11C when the light source output is _{greater: I a '= {I 01} · exp (-μ 1 · C 1 · L 1) + I 1 + C 1 · I 3 + C 2 · I 4 ｝ · Exp (−α · L ₂ ) + I ₂ (12) (b) Detected infrared ray amount of measurement cell 11C when light source output is small: I _{b ′} = ｛I ₀₂ · exp (−μ ₁ · _{C 1 · L 1) + I} 1 + C 1 · I 3 + C 2 · I 4} · exp (-α · L 2) + I 2 ··· (13) (c) of the compensation cell 12C when the light source output is greater Detected infrared light amount: I _{c ′} = {I ₀₁ + I ₁ } · exp (−α · L ₂ ) + I ₂ (14) (d) Detected infrared light amount of compensation cell 12C when light source output is small: I _{d ′} = {I ₀₂ + I ₁ } · exp (−α · L ₂ ) + I ₂ (15)

Next, the measuring cell 11C and the compensating cell 12C
In each case, the amount of infrared radiation emitted from the light sources 41 and 42 is
Difference in detected infrared light amount between large and small (Equation (12)
-Expression (13), Expression (14)-Expression (15)). this
Radiation from the cells 11C and 12C and the transmission window 21
Eliminates the effects of radiation from C and 22C and radiation from detected gas
From the light source 41 in the measurement cell 11C
The sample gas in the measurement cell 11C and the transmission
Component (Equation (16)) transmitted through overwindow 21C, and compensation
In the infrared rays emitted from the light source 42 in the cell 12C,
Of inert gas and permeation window 22C in compensation cell 12C
Is obtained (Equation (17)). I_{a '}-I_{b '}= (I₀₁-I₀₂) · Exp (−μ₁・ C₁・ L₁) Exp (-α · L _Two ) ... (16) I_{c '}-I_{d '}= (I₀₁-I₀₂) · Exp (-α · L_Two) ・ ・ ・ (17)

Finally, the ratio of the expression (16) to the expression (17) is obtained to obtain the concentration C _{1 of the} detected gas. C ₁ = (μ ₁ · L ₁ ) ^-1 ln {(I _{c ′} −I _{d ′} ) / (I _{a ′} −I _{b ′} )} (18)

[0040] Thus, two cells 11C, the amount of infrared I _{a '~I d'} obtained from 12C to detect gas concentration in the sample gas by substituting the equation (18) is obtained.

According to the present embodiment, similarly to the first embodiment, high-precision concentration measurement can be performed immediately without sufficient warming-up and calibration, and only two cells are required. It is compact.

When this apparatus was used to measure 100 ppm of CO gas using nitrogen as a carrier gas as a sample gas, an accuracy of ± 10% was obtained immediately after the apparatus was started.

[0043] In the case of using a mounted measured gas concentration of this device on a vehicle or the like to control the vehicle, the calculation of the correction and Formula absorption coefficient μ ₁ (18) is configured to perform in software of the microcomputer It is good to do.

In the first embodiment, the second measurement cell 11B and the second compensation cell 12B are not provided with a light source, but the cells 11B and 12B are also configured to irradiate infrared rays from the light source. You can also. in this case,
The irradiation light amount is set to be different between the light source for the first measurement cell 11A and the first compensation cell 12A and the light source for the second measurement cell 11B and the second compensation cell 12B. That is, the amount of irradiation infrared light from the light source for the first measurement cell 11A and the first compensation cell 12A is I ₀₁ , and the amount of irradiation infrared light from the light source for the second measurement cell 11B and the second compensation cell 12B is I ₀₂ . Then, the equations become the same as the equations (12) to (18) of the second embodiment, so that the equation (18) can be used as the equation for calculating the density.

The gas concentration measuring method of the present invention can also be carried out by obtaining detection outputs when the light source is off and on by the infrared gas analyzer (FIG. 6). Is arbitrary as long as it does not contradict the purpose of the present invention.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a gas concentration measuring device of the present invention used in a gas concentration measuring method of the present invention.

FIG. 2 is a diagram illustrating the operation of the gas concentration measuring device.

FIG. 3 is a configuration diagram of another gas concentration measuring device of the present invention used in the gas concentration measuring method of the present invention.

FIG. 4 is a time chart for explaining the operation of the gas concentration measuring device.

FIG. 5 is a diagram illustrating the operation of the gas concentration measuring device.

FIG. 6 is a configuration diagram of a gas concentration measurement device used in a conventional gas concentration measurement method.

[Explanation of symbols]

11A, 11B, 11C Measurement cells 12A, 12B, 12C Compensation cells 21A, 21B, 22A, 22B, 21C, 22C, 2
3, 24, 23C, 24C Transmission window 31A, 31B, 32A, 32B, 31C, 32C Optical sensor (detector) 41, 42 Light source 5 Filter 61, 62 Heater block 72 Controller (capturing means)

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takahiro Nitta 14 Iwatani, Shimowakaku-cho, Nishio-shi, Aichi Japan (72) Inventor Jun Atsushi Hashikawa 14 Iwatani, Shimowakaku-cho, Nishio-shi, Aichi (72) Inventor Naruyuki Kawazu 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation F-term (reference) 2G059 AA01 BB01 DD12 EE01 FF08 HH01 JJ02 KK03 MM01 MM14

Claims (4)

[Claims] 1. A sample gas is introduced into a measurement cell, a predetermined comparison gas is introduced into a compensation cell, and infrared rays are irradiated from a light source into two types of cells having different introduced gases. In the gas concentration measurement method of detecting the amount of infrared light emitted from the transmission window by the detector arranged behind the window and measuring the concentration of the component gas to be detected in the sample gas from the detected amount of infrared light in both cells, A first detection procedure for obtaining a detection infrared ray amount in the measurement cell in a state where the irradiation infrared ray amount is large, and a second detection procedure for obtaining a detection infrared ray amount in the measurement cell in a state where the irradiation infrared ray amount from the light source is small. A third detection procedure for obtaining the amount of infrared radiation detected in the compensation cell when the amount of infrared radiation emitted from the light source is large; and detecting the amount of infrared radiation in the compensation cell when the amount of infrared radiation emitted from the light source is small. And then the difference between the amount of infrared radiation detected in the first detection procedure and the amount of infrared radiation detected in the second detection procedure, and the amount of infrared radiation detected in the third detection procedure and the fourth detection procedure Taking the difference from the detected amount of infrared light, obtaining only the transmitted component of infrared light from the light source for each of the measurement cell and the compensation cell, and then calculating the concentration of the component gas based on both transmitted components. Gas concentration measurement method. 2. A gas concentration measuring apparatus used in the gas concentration measuring method according to claim 1, wherein said measuring cell includes first and second measuring cells, and said compensating cell includes first and second measuring cells. Irradiating the first light source with infrared light more strongly than the second measurement cell, and applying the second light source toward the first compensation cell.
Irradiates infrared light more strongly than the compensation cell of the above. The amount of infrared light detected in the first detection procedure is obtained by the first measurement cell, and the amount of infrared light detected in the second detection procedure is obtained by the second measurement cell. A gas concentration measuring device, wherein the amount of infrared rays detected in the third detection procedure is obtained by a first compensation cell, and the amount of infrared rays detected in the fourth detection procedure is obtained by a second compensation cell. . 3. The gas concentration measuring device according to claim 2, wherein the light source is constituted only by the light source for the first measurement cell and the light source for the first compensation cell. 4. A gas concentration measuring device used in the gas concentration measuring method according to claim 1, comprising one each of said measuring cell and said compensating cell, and wherein said light source is capable of switching the amount of irradiated infrared light freely. And measuring means for detecting the amount of infrared radiation detected in the first detection procedure when the amount of irradiated infrared radiation is large. , The amount of infrared rays detected in the second detection procedure is set as the detection output by the measuring cell when the amount of irradiation infrared rays is small, and the amount of infrared rays detected in the third detection procedure is used as the detection output when the amount of irradiation infrared rays is large. The detection output by the compensation cell is used as the detection output by the compensation cell when the irradiation infrared ray amount is small in the fourth detection procedure. Concentration measuring device.