JP2005024391A - Optical gas analyzer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical gas analyzer for appropriately suppressing the deterioration of analysis precision by variations in the inner pressure of a measurement part. <P>SOLUTION: A gas inlet 13 connected to a combustion chamber C that is a measurement part via piping 22, an analysis chamber 14, where the sample gas in the combustion chamber C introduced via the gas inlet 13 flows continuously, and a gas outlet 15 for discharging the sample gas from the analysis chamber 14 are provided inside an analysis cell 12 of the optical gas analyzer 10. The gas outlet 15 is connected to a surge tank 22 for accumulating pressure. A flow control valve 26 is operated, based on the detection result of a pressure sensor 23, and maintains the inner pressure of the surge tank 22 at set pressure. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical gas analyzer.
[0002]
[Prior art]
Conventionally, an optical gas that allows light such as infrared rays to pass through a sample gas and performs gas analysis such as concentration detection of the specific component contained in the sample gas based on the change in the amount of light of the specific wavelength component of the light accompanying the passage. An analyzer is known (Patent Document 1, etc.).
[0003]
FIG. 6 shows an example of such a conventional optical gas analyzer. The optical gas analyzer 50 illustrated in the figure is used for detecting the concentration of carbon dioxide contained in the gas in the combustion chamber C of the internal combustion engine. As shown in the figure, the optical gas analyzer 50 is mainly configured to include an analysis cell 51, a light source 52 that generates infrared rays, and a detection unit 53 that detects the light amount of a specific wavelength component of infrared rays. .
[0004]
In the analysis cell 51, a gas inlet 55 connected to the combustion chamber C through a pipe 54, an analysis chamber 56 in which the sample gas introduced through the gas inlet 55 is continuously flowed, and the sample gas in the analysis chamber 56 to the outside air A gas outlet 57 for discharging is formed. The light source 52 and the detection unit 53 are disposed on both sides of the analysis cell 51 in the sample gas flow direction, and infrared rays emitted from the light source 52 pass through the analysis chamber 54 and enter the detection unit 53. It has come to be. The detection unit 53 includes an optical filter 58 that transmits only a specific wavelength component of infrared light, and an infrared sensor 59 that detects the amount of light of the specific wavelength component received through the optical filter 58.
[0005]
[Patent Document 1]
JP-A-2002-267596 [0006]
[Problems to be solved by the invention]
In such a conventional optical gas analyzer 50, the sample gas is introduced into the analysis chamber 54 by natural intake using the differential pressure between the internal pressure of the combustion chamber C, which is a measurement site, and the atmospheric pressure. For this reason, when the internal pressure of the measurement site is near atmospheric pressure or negative pressure below atmospheric pressure, the amount of sample gas introduced into the analysis chamber 54 is insufficient, and an appropriate analysis result is obtained. As described above, the internal pressure fluctuation at the measurement site is likely to affect the analysis accuracy.
[0007]
The present invention has been made in view of such circumstances, and an object of the present invention is to provide an optical gas analyzer that can suitably suppress deterioration in analysis accuracy due to fluctuations in internal pressure at a measurement site.
[0008]
[Means for Solving the Problems]
In the following, means for achieving the above-described object and its operational effects are described.
The invention according to claim 1 has an analysis chamber in which a sample gas of a measurement site is continuously flowed, and the sample is based on a light amount change of a specific wavelength component of a light beam that has passed through the sample gas in the analysis chamber. In an optical gas analyzer for analyzing a gas component, a pressure reservoir provided downstream in the flow direction of the sample gas in the analysis chamber, and pressure control means for controlling the internal pressure of the pressure reservoir to be maintained constant The gist is to provide the above.
[0009]
In the above configuration, the downstream side in the sample gas flow direction of the analysis chamber can be maintained at a desired pressure through the control of the internal pressure of the pressure reservoir by the pressure control means. Therefore, if the internal pressure of the pressure reservoir is appropriately controlled, it is possible to introduce sufficient sample gas into the analysis chamber even when the pressure at the measurement site is near atmospheric pressure or lower than that. Become. For example, if the internal pressure of the pressure reservoir is controlled to a pressure sufficiently lower than the lower limit of the pressure fluctuation range of the measurement site, a sufficient amount of sample gas can be stably introduced into the analysis chamber even when the measurement site pressure drops. Will come to be. Therefore, according to the said structure, the deterioration of the analysis precision by the internal pressure fluctuation | variation of a measurement site | part can be suppressed suitably.
[0010]
According to a second aspect of the present invention, in the optical gas analyzer according to the first aspect, the flow passage area of the gas outlet communicating the analysis chamber and the pressure reservoir is changed to the flow passage area of the analysis chamber. The gist is that it is larger than that.
[0011]
In the above configuration, the pressure in the analysis chamber is maintained substantially equal to the internal pressure of the pressure reservoir regardless of the change in the amount of sample gas introduced into the analysis chamber. That is, an increase in the internal pressure of the analysis chamber due to a large amount of sample gas introduced can be suppressed. Therefore, the introduction of the sample gas to the analysis cell can be further stabilized.
[0012]
The invention described in claim 3 is the optical gas analyzer according to claim 1 or 2, wherein the volume of the pressure reservoir is 10,000 times or more the volume of the analysis chamber. And
[0013]
In order to suppress the internal pressure fluctuation of the pressure reservoir due to the inflow of the sample gas that has passed through the analysis chamber, the volume of the pressure reservoir may be sufficiently larger than the volume of the analysis chamber. As the volume ratio of the pressure reservoir to the analysis chamber increases, the influence of the inflow of the sample gas on the internal pressure of the pressure reservoir decreases. However, when the volume ratio exceeds 10,000, the improvement effect of the internal pressure fluctuation reaches a peak. It has been confirmed. Therefore, as in the above configuration, if the volume of the pressure reservoir is 10,000 times or more the volume of the analysis chamber, fluctuations in the internal pressure of the pressure reservoir can be effectively suppressed.
[0014]
Furthermore, the invention according to claim 4 has an analysis chamber in which the sample gas of the measurement site is continuously flowed, and based on the light amount change of the specific wavelength component of the light beam that has passed through the sample gas in the analysis chamber, The gist of the optical gas analyzer for analyzing the component of the sample gas is that a rectifying plate for rectifying the sample gas is provided at the gas inlet of the analysis chamber.
[0015]
When the internal pressure of the measurement site decreases and the amount of sample gas introduced into the analysis chamber decreases, the flow of sample gas in the analysis chamber becomes biased, and the replacement efficiency of the sample gas in the analysis chamber decreases. May get worse. In that respect, in the above configuration, since the sample gas is rectified by the rectifying plate when introduced into the analysis chamber, stagnation of the sample gas in the analysis chamber is suppressed. Therefore, according to the said structure, the deterioration of the analysis precision by the internal pressure fluctuation | variation of a measurement site | part can be suppressed suitably.
[0016]
According to a fifth aspect of the present invention, there is provided the optical gas analyzer according to the fourth aspect, wherein the rectifying plate is a concentration of the flow of the sample gas to a central portion of the flow path of the analysis chamber. The gist of the present invention is that it is formed in a shape that suppresses the above.
[0017]
When the amount of sample gas introduced is reduced, the wall resistance causes the stagnation of the sample gas flow around the flow path in the analysis chamber. In particular, when the flow channel area in the analysis chamber is larger than the flow channel area at the gas inlet, such a tendency becomes more remarkable. In that respect, in the above configuration, since the concentration of the sample gas flow to the central portion of the flow channel of the analysis chamber is suppressed by the rectifying plate, the stagnation of the sample gas flow around the flow channel can be preferably eliminated. it can.
[0018]
If the internal pressure at the measurement site fluctuates, the amount of sample gas introduced into the analysis chamber is likely to fluctuate, which causes deterioration in analysis accuracy. Even if the internal temperature of the measurement site varies, the amount of sample gas introduced into the analysis chamber substantially varies due to thermal expansion of the sample gas. Therefore, as described in claim 6, the present invention is effectively applied to an optical gas analyzer in which at least one of the internal pressure and the internal temperature varies as a measurement site. Further, as described in claim 7, by applying the present invention to an optical gas analyzer used for gas analysis in a combustion chamber of an internal combustion engine in which the internal pressure and the internal temperature fluctuate greatly, a more remarkable effect can be obtained. Can do.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the optical gas analyzer of the present invention will be described in detail with reference to the drawings. In the optical gas analyzer of the present embodiment, a pressure-controlled surge tank is disposed downstream of the analysis chamber in the sample gas flow direction, and a rectifying plate is disposed at the gas inlet of the analysis chamber. Analysis accuracy deterioration due to fluctuations in internal pressure at the measurement site is suppressed.
[0020]
FIG. 1 shows the overall structure of the optical gas analyzer 10 of this embodiment. The optical gas analyzer 10 is configured as a gas analyzer for detecting the carbon dioxide concentration in the combustion chamber C of the internal combustion engine.
[0021]
The combustion chamber C, which is a measurement site, is connected to the gas inlet 13 of the analysis cell 12 through the pipe 11. In the analysis cell 12, an analysis chamber 14 into which the sample gas is introduced through the gas inlet 13 and a gas outlet 15 for discharging the sample gas from the analysis chamber 14 are provided. Glass windows 18 and 19 are provided on the partition walls on both sides of the sample gas flow direction of the analysis cell 12, respectively, and condenser lenses 20 and 21 are provided on the sides of the glass windows 18 and 19, respectively.
[0022]
The gas outlet 15 of the analysis cell 12 is connected to a surge tank 22. The surge tank 22 is provided with a pressure sensor 23 that detects its internal pressure. A pipe 24 is connected to the surge tank 22. The pipe 24 is branched into two on the way. One side of the pipe 24 that has been removed is connected to a vacuum pump 25 that sucks the gas in the surge tank 22 and exhausts it outside, and the other is opened to the atmosphere via a flow control valve 26. Based on the detection result of the pressure sensor 23, the flow control valve 26 adjusts its opening so that the internal pressure of the surge tank 22 is maintained at a predetermined set pressure.
[0023]
Next, the configuration of the optical system of the optical gas analyzer 10 will be described. The optical system of the optical gas analyzer 10 mainly includes a light source 30 and a detection unit 34 that detects a light amount of a specific wavelength component of light emitted from the light source 30. In the optical gas analyzer 10 of the present embodiment that detects the carbon dioxide concentration, an infrared lamp that emits light in a wavelength region near the absorption wavelength of carbon dioxide is used as the light source 30. The detection unit 34 is configured to detect the light amount of the absorption wavelength component of carbon dioxide.
[0024]
The light source 30 is disposed on the side of the condenser lens 20 of the analysis cell 12. A chopper 31 is interposed between the analysis cell 12 and the light source 30. The chopper 31 is a disk in which slits 32 are formed at regular intervals in the circumferential direction. The chopper 31 is rotated by a motor 33, and according to the rotation, infrared light incident from the light source 30 to the condenser lens 20 is allowed / blocked at regular time intervals.
[0025]
The detector 34 is disposed on the side of the condenser lens 21 of the analysis cell 12. The detection unit 34 includes an optical filter 35 that transmits only the absorption wavelength component of infrared carbon dioxide, and an infrared sensor 36 that detects the light amount of the specific wavelength component that has entered through the optical filter 35. ing.
[0026]
The optical gas analyzer 10 is provided with temperature adjusting means for maintaining the temperature of the sample gas flowing through the analysis chamber 14 constant in order to stabilize the analysis result. The temperature adjusting means includes a thermocouple 37, a heater 38, and a temperature adjusting circuit 39. The thermocouple 37 is disposed in the vicinity of the gas inlet 13 of the analysis cell 12, and the heater 38 is disposed around the analysis cell 12 and the pipe 11. Based on the detection result of the thermocouple 37, the temperature adjustment circuit 39 performs energization control of the heater 38 so that the detected temperature of the thermocouple 37 is maintained at a predetermined temperature set in advance.
[0027]
Next, a sample gas analysis mode of the optical gas analyzer 10 will be described.
The vacuum pump 25 sucks the gas in the surge tank 22 through the pipe 24 and reduces the internal pressure of the surge tank 22. The pressure sensor 23 detects the internal pressure of the surge tank 22 and outputs it to the flow control valve 26. The flow control valve 26 adjusts the opening degree based on the detection result of the pressure sensor 23 so that the inside of the surge tank 22 is maintained at the set pressure. That is, the flow control valve 26 adjusts the balance between the exhaust amount of the gas from the surge tank 22 by the vacuum pump 25 and the flow rate of the outside air introduced into the pipe 24 through the flow control valve 26, so that the surge tank 22. The inside is maintained at the set pressure. The set pressure is set to a value sufficiently lower than the atmospheric pressure and lower than the lower limit of the pressure fluctuation range in the combustion chamber C during engine operation.
[0028]
In this optical gas analyzer 10, the flow passage area of the gas outlet 15 is formed sufficiently larger than the flow passage area of the analysis chamber 14. Therefore, even when the internal pressure of the combustion chamber C increases and the amount of sample gas introduced into the analysis chamber 14 increases, the internal pressure of the analysis chamber 14 is maintained at substantially the same level as the internal pressure of the surge tank 22. That is, the inside of the analysis chamber 14 is maintained at the set pressure as in the surge tank 22.
[0029]
Note that the set pressure is set to a value equal to or lower than the atmospheric pressure at which a sufficient amount of sample gas for ensuring analysis accuracy can be continuously introduced into the analysis chamber 14. Such a predetermined pressure can be obtained in advance through experiments, analysis, and the like.
[0030]
Incidentally, if it is desired to ensure a sufficient amount of sample gas introduced, the set pressure may be set to a pressure sufficiently lower than the lower limit of the internal pressure fluctuation range of the combustion chamber C during engine operation. However, according to the results of tests conducted by the inventors, even if the set pressure of the surge tank 22 is 50 kPa with respect to the combustion chamber C in which the lower limit of the pressure fluctuation range during engine operation is 15 to 25 kPa, It has been confirmed that a sufficient amount of sample gas is stably introduced into the analysis chamber 14. That is, when the part where the internal pressure fluctuation occurs in a very short cycle like the combustion chamber C is the measurement part, even if the set pressure is set to a pressure slightly higher than the lower limit of the internal pressure fluctuation range of the measurement part, It is possible to stably secure a sufficient amount of sample gas introduced.
[0031]
The sample gas in the combustion chamber C is sucked by the differential pressure between the internal pressure of the surge tank 22 and the internal pressure of the combustion chamber C controlled to maintain such a set pressure, and is introduced into the analysis cell 12. Then, the sample gas flows into the analysis chamber 14 from the gas inlet 13 through the rectifying plate 16 and is discharged from the gas outlet 15 to the surge tank 22. At this time, since the internal pressure of the surge tank 22 is maintained at the above set pressure by the flow control valve 26, even if the internal pressure of the combustion chamber C becomes atmospheric pressure or a negative pressure lower than that, the above difference The pressure is maintained at a sufficient level, and a sufficient amount of sample gas is introduced into the analysis cell 12.
[0032]
In addition, if the internal pressure of the surge tank 22 fluctuates with the inflow of the sample gas from the analysis chamber 14, the introduction of the sample gas into the analysis cell 12 becomes unstable. In order to suppress the internal pressure fluctuation of the surge tank 22, the volume of the surge tank 22 needs to be sufficiently larger than the volume of the analysis chamber 14.
[0033]
The inventors have investigated the influence of the volume of the surge tank 22 on the fluctuation of its internal pressure. As shown in FIG. 2, the larger the volume ratio of the surge tank 22 to the analysis chamber 14, the smaller the influence of the sample gas inflow on the internal pressure of the surge tank 22, and the maximum fluctuation amount of the internal pressure of the surge tank 22 Becomes smaller. However, when the volume ratio exceeds 10,000, the improvement effect of the internal pressure fluctuation reaches its peak, and the maximum fluctuation amount of the internal pressure hardly decreases. Therefore, if the volume of the surge tank 22 is 10,000 times or more the volume of the analysis chamber 14, fluctuations in the internal pressure of the surge tank 22 can be effectively suppressed. In the optical gas analyzer 10, the surge tank 22 is set to a volume approximately 10,000 times larger than the volume of the analysis chamber 14, thereby suppressing an increase in the volume of the surge tank 22 while suppressing fluctuations in internal pressure. I am doing so.
[0034]
Incidentally, although it is possible to introduce the sample gas directly into the analysis cell 12 by the vacuum pump 25 without providing the surge tank 22, the sample gas flow in the analysis cell 12 is disturbed and the amount of sample gas introduced. There is a possibility that the fluctuation of the analysis will increase and the analysis accuracy will be lowered. In that respect, if the surge tank 22 with pressure control as described above is provided to keep the pressure downstream of the analysis cell 12 in the sample gas flow direction static, the flow of the sample gas in the analysis cell 12 can be reduced. It is possible to stabilize and ensure high analysis accuracy.
[0035]
In the analysis chamber 14 into which the sample gas is introduced in this way, infrared rays generated by the light source 30 are intermittently incident through the chopper 31, the condenser lens 20, and the glass window 18. This infrared light passes through the sample gas flowing through the analysis chamber 14 at right angles to the flow. When passing through the sample gas, the absorption wavelength component of infrared carbon dioxide is absorbed by the carbon dioxide in the sample gas, and the amount of light is reduced.
[0036]
Infrared rays that have passed through the sample gas are incident on the detector 34 via the glass window 19 and the condenser lens 21. The optical filter 35 of the detection unit 34 transmits only the absorption wavelength component of carbon dioxide in infrared rays to the infrared sensor 36. The infrared sensor 36 detects the light amount of the absorption wavelength component of carbon dioxide that has passed through the optical filter 35. At this time, if the carbon dioxide concentration of the sample gas is high, the amount of absorption of the absorption wavelength component of carbon dioxide increases, and the amount of light detected by the infrared sensor 36 decreases. Therefore, the detection result of the infrared sensor 36 reflects the carbon dioxide concentration of the sample gas.
[0037]
Note that the inner diameter and length of the pipe 11 connecting the combustion chamber C, which is a measurement site, and the analysis chamber 14 affect the analysis accuracy of the sample gas. The inner diameter and length of the pipe 11 of the optical gas analyzer 10 are set as follows in consideration of such influence.
[0038]
The inner diameter of the pipe 11 is set to minimize the increase in dead volume (the volume of the pipe 11) that deteriorates the analysis accuracy within a range in which a decrease in responsiveness due to deterioration of the sample gas flow due to wall resistance can be suitably avoided. Is set to Incidentally, by the inventors, the responsiveness can be sufficiently secured by setting the inner diameter of the pipe 11 to 0.4 mm or more, and the responsiveness does not improve much even if the inner diameter of the pipe 11 is further increased beyond 1 mm. It has been confirmed. Therefore, the desirable inner diameter of the pipe 11 is in the range of 0.4 to 1 mm.
[0039]
Further, the length of the pipe 11 is set so that the fluctuation of the sample gas temperature in the analysis chamber 14 due to the fluctuation of the internal temperature of the combustion chamber C can be suppressed to the extent that the analysis accuracy is not deteriorated. If the length of the pipe 11 is 500 times the inner diameter or more, the fluctuation of the sample gas temperature in the analysis chamber 14 during the analysis is kept to 1% or less, and the deterioration of the analysis accuracy due to the change of the sample gas temperature can be sufficiently suppressed. The inventors have confirmed that this is the case. That is, when the inner diameter of the pipe 11 is 0.4 mm, the length is 200 mm or more. When the inner diameter of the pipe 11 is 1 mm, the length is 500 mm or more. The temperature fluctuation of the sample gas can be suitably suppressed.
[0040]
FIG. 3 shows a cross-sectional structure of the analysis cell 12 of such an optical gas analyzer 10.
As shown in the figure, a rectifying plate 16 for rectifying the sample gas introduced into the analysis chamber 14 is disposed at a connection portion between the gas inlet 13 of the analysis cell 12 and the analysis chamber 14. In the optical gas analyzer 10 of the present embodiment, the flow path area of the gas inlet 13 is smaller than the flow path area of the analysis chamber 14, and the sample gas extends from the upstream side to the downstream side of the rectifying plate 16. The flow path area of is enlarged. The rectifying plate 16 whose planar structure is shown in FIG. 4 (a) and whose side cross-sectional structure is shown in FIG. 4 (b) is provided with a shielding plate 16a at the center for blocking the flow of the sample gas. It is formed so that the opening 16b is provided only in the portion.
[0041]
Next, the operation of the rectifying plate 16 will be described.
FIG. 5A shows the flow of the sample gas in the analysis cell 12 when there is no rectifying plate 16. As described above, in the analysis cell 12, the flow area of the sample gas is enlarged from the gas inlet 13 to the analysis chamber 14, so that when the flow rate of the sample gas is small, the flow of the sample gas is the flow of the analysis chamber 14. The sample gas concentrates in the center of the path, and the flow of the sample gas around the flow path of the analysis chamber 14 becomes stagnant. Therefore, when the amount of sample gas introduced is reduced, the substituting property of the sample gas in the analysis chamber 14 is deteriorated and the analysis accuracy is lowered. Incidentally, even if the gas inlet 13 and the analysis chamber 14 have the same flow path area, the flow of the sample gas around the analysis chamber 14 may be stagnant due to wall resistance.
[0042]
On the other hand, when the rectifying plate 16 is provided, the flow of the sample gas is guided to the periphery of the flow path of the analysis chamber 14 by the rectifying plate 16 as shown in FIG. As a result, the concentration of the sample gas flow in the central portion of the flow path of the analysis chamber 14 is suppressed, and the stagnation of the peripheral portion of the flow path is eliminated, so that replacement of the sample gas in the analysis chamber 14 is promoted.
[0043]
As the rectifying plate, a rectifying plate 16 ′ made of a mesh formed of metal or the like as shown in FIG. Similarly, the rectifying plate 16 ′ can suppress the concentration of the sample gas flow in the center of the flow path of the analysis chamber 14 and promote the replacement of the sample gas in the analysis chamber 14.
[0044]
In the optical gas analyzer 10 of the present embodiment, the surge tank 22 has a configuration corresponding to the pressure reservoir. Further, the pressure control means is controlled by the pressure sensor 23 and the flow rate control valve 26.
[0045]
According to this embodiment described above, the following effects can be obtained.
(1) Since the pressure on the downstream side in the sample gas flow direction of the analysis cell 12 is controlled to a constant negative pressure, sufficient sample gas is introduced into the analysis cell 12 even when the combustion chamber C is under atmospheric pressure, Stable analysis can be performed.
[0046]
(2) Since the flow passage area of the gas outlet 15 of the analysis cell 12 is sufficiently larger than the flow passage area of the analysis chamber 14, regardless of changes in the amount of sample gas introduced due to fluctuations in the internal pressure of the combustion chamber C The internal pressure of the analysis chamber 14 can be maintained constant, and a smooth sample gas flow can be maintained.
[0047]
(3) Since the stagnation of the sample gas flow is suppressed by the rectifying plates 16 and 16 ′, the replacement of the sample gas in the analysis chamber 14 is promoted, so that the amount of sample gas introduced into the analysis cell 12 is changed. Regardless, the analysis accuracy can be suitably maintained.
[0048]
(4) Since the flow of the sample gas in the analysis chamber 14 is rectified and infrared rays are allowed to pass perpendicularly to the rectified sample gas flow, the change in the amount of sample gas introduced into the analysis cell 12 Regardless of this, high analysis accuracy can be secured stably.
[0049]
(5) Since the volume of the surge tank 22 is 10,000 or more times the volume of the analysis chamber 14 and the internal pressure fluctuation of the surge tank 22 is sufficiently suppressed, further introduction of the sample gas into the analysis cell 12 Stabilization can be achieved.
[0050]
In addition, the said embodiment can also be changed and implemented as follows.
-You may employ | adopt things other than the shape illustrated to Fig.5 (a)-(c) as a baffle plate. Whatever the shape, the same effect as that of the rectifying plates 16 and 16 ′ of the above embodiment can be obtained as long as the shape suppresses the concentration of the flow in the central portion of the flow path of the analysis chamber 14. Further, even if the shape of the flow path of the analysis chamber 14 is not limited to the central portion of the flow path, any flow straightening plate that rectifies the sample gas flowing into the analysis chamber 14 may be used. A certain effect can be exerted in suppressing stagnation of the sample gas.
[0051]
The pressure in the surge tank 22 may be controlled using means other than the flow control valve 26. For example, if the operation amount of the vacuum pump 25 is adjusted based on the detection result of the pressure sensor 23, the inside of the surge tank 22 can be maintained at the set pressure without using the flow control valve 26.
[0052]
In the above embodiment, the measurement site is measured through both the provision of the surge tank 22 controlled to a constant pressure downstream of the analysis chamber 14 and the arrangement of the rectifying plate 16 at the gas inlet 13 of the analysis chamber 14. Although the deterioration of the analysis accuracy due to the pressure state is suppressed, only one of them may be adopted.
[0053]
If the wavelength component for detecting the change in the amount of light by the detection unit is changed by changing the wavelength range of the light beam generated by the light source, the characteristics of the optical filter, etc., the optical gas analyzer 10 of the above embodiment is changed to a gas other than carbon dioxide. It can be used for component analysis.
[0054]
In the above embodiment, the optical gas analyzer 10 for analyzing gas in the combustion chamber C of the internal combustion engine has been described as an example. However, the present invention can also be used for other gas analyses.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing the overall structure of an optical gas analyzer according to an embodiment of the present invention.
FIG. 2 is a graph showing the relationship between the volume ratio of the surge tank to the analysis chamber and the maximum fluctuation amount of the surge tank internal pressure.
FIG. 3 is a cross-sectional view of an analysis cell applied to the optical gas analyzer of the embodiment.
4A is a plan view of a rectifying plate applied to the embodiment, FIG. 4B is a side sectional view, and FIG. 4C is a plan view of a modification thereof;
FIGS. 5A and 5B are diagrams showing a flow of sample gas in an analysis cell when there is no rectifying plate and when FIG.
FIG. 6 is a schematic diagram showing the overall structure of a conventional optical gas analyzer.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Optical gas analyzer, 11 ... Piping, 12 ... Analysis cell, 13 ... Gas inlet, 14 ... Analysis chamber, 15 ... Gas outlet, 16, 16 '... Rectification plate, 16a ... Shielding plate, 16b ... Opening, 18 , 19 ... Glass window, 20, 21 ... Condensing lens, 22 ... Surge tank (pressure reservoir), 23 ... Pressure sensor, 24 ... Piping, 25 ... Vacuum pump, 26 ... Flow control valve, 30 ... Light source, 31 ... Chopper DESCRIPTION OF SYMBOLS 31 ... Slit, 33 ... Motor, 34 ... Detection part, 35 ... Optical filter, 36 ... Infrared sensor, 37 ... Thermocouple, 38 ... Heater, 39 ... Temperature control circuit, 50 ... Optical gas analyzer, 51 ... Analysis cell , 52 ... light source, 53 ... detection section, 54 ... analysis chamber, 55 ... piping, 56 ... gas inlet, 57 ... gas outlet, 58 ... optical filter, 59 ... infrared sensor, C ... combustion chamber (measurement site).

Claims (7)

An optical gas that has an analysis chamber in which the sample gas at the measurement site is continuously flowed, and performs component analysis of the sample gas based on a change in the amount of light of a specific wavelength component of the light beam that has passed through the sample gas in the analysis chamber In the analyzer
A pressure reservoir provided downstream in the flow direction of the sample gas in the analysis chamber;
Pressure control means for controlling the internal pressure of the pressure reservoir to be kept constant;
An optical gas analyzer comprising: The optical gas analyzer according to claim 1, wherein a flow passage area of a gas outlet communicating with the analysis chamber and the pressure reservoir is larger than a flow passage area of the analysis chamber. The optical gas analyzer according to claim 1 or 2, wherein the volume of the pressure reservoir is 10,000 times or more the volume of the analysis chamber. An optical gas that has an analysis chamber in which the sample gas at the measurement site is continuously flowed, and performs component analysis of the sample gas based on a change in the amount of light of a specific wavelength component of the light beam that has passed through the sample gas in the analysis chamber In the analyzer
An optical gas analyzer characterized in that a rectifying plate for rectifying the sample gas is provided at a gas inlet of the analysis chamber. 5. The optical gas analyzer according to claim 4, wherein the rectifying plate is formed in a shape that suppresses concentration of the flow of the sample gas to the central portion of the flow path of the analysis chamber. The optical gas analyzer according to any one of claims 1 to 5, wherein the optical gas analyzer performs component analysis of the sample gas using a site where at least one of internal pressure and internal temperature varies as the measurement site. . The optical gas analyzer according to any one of claims 1 to 5, which is used for gas analysis in a combustion chamber of an internal combustion engine.

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