JP2009174868A - Correlation cell, gas analyzer, and assembling method of correlation cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a correlation cell capable of suppressing the occurrence of a gas leak after a gas is sealed, a gas analyzer, and an assembling method of the correlation cell. <P>SOLUTION: A wheel 4 has a communication passage 44 extending in a radial direction from the outer peripheral surface to form a female screw and an almost flatly formed attaching surface 46. A window plate 5 is a light pervious plate material having a predetermined thickness. A screw member 6 has a male screw part 63, the end part 61 being the leading end of the male screw part 63, and a screw head 62 of which the diameter is larger than that of the male screw part 63. In relation to the length direction of the communication passage 44 of the wheel 4, the position of the end part 47 of the wheel 4 is nearer to a measuring gas chamber 42 or a comparing gas chamber 43 than the position of the end part 61 of the screw member 6. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a correlation cell, a gas analyzer, and a method for assembling a correlation cell, which are used in an infrared absorption measurement apparatus using a gas correlation method.

Conventionally, a gas correlation method has been used for measuring various gas concentrations including CO and CO ₂ . This gas correlation method is an infrared absorption measurement method. Specifically, a measurement target gas chamber in which a measurement target gas such as CO is sealed and an inert gas (zero gas, comparison gas) such as N ₂ are sealed. The gas concentration is measured using a gas correlation cell (correlation cell) that also has a comparative gas chamber. That is, this correlation cell is arranged between a sample cell into which a sample gas containing a measurement target gas is introduced and an infrared light source that causes infrared light to enter the sample cell. Then, by rotating the correlation cell, the difference between the transmitted infrared light amount of the sample cell when the measurement target gas is present on the optical path of the infrared light and the transmitted infrared light amount of the sample cell when the inert gas is present Thus, the concentration of the measurement target gas in the sample gas is measured.

As the correlation cell used in such a gas correlation method, those having various structures have been conventionally proposed (for example, see Patent Document 1).
This Patent Document 1 discloses a correlation cell or the like with a small degree of gas leakage during gas filling operation. That is, this correlation cell has a measurement gas chamber in which the same kind of gas as the detection target gas is sealed and a comparison gas chamber in which a comparison gas is sealed, and communicates with each of the measurement gas chamber and the comparison gas chamber. This is obtained by sealing a gas sealing flow path and then sealing a predetermined gas in each of the measurement gas chamber and the comparison gas chamber.

JP 2007-199032 A

Here, the gas leakage about the correlation cell becomes a problem not only during the gas filling operation but also after the gas filling. Since gas leakage after gas filling has an adverse effect on measurement accuracy, a correlation cell in which the airtightness is maintained without change over time is required. Various causes are conceivable as the cause of such gas leakage after gas filling. For example, there may be a case where the bonding surface for bonding a plurality of members for partitioning the gas chamber is distorted.
About the gas leakage at the time of gas filling operation, it is possible to cope with the conventionally proposed technology, but no gas leakage after gas filling has been proposed.

  The present invention has been made to solve the technical problems as described above, and an object of the present invention is to provide a correlation cell, a gas analyzer, and a correlation that can suppress the occurrence of gas leakage after the gas is sealed. It is to provide a method for assembling a cell.

  For this purpose, a correlation cell to which the present invention is applied includes a cell main body and a translucent plate attached to the cell main body, and a plurality of gas chambers are formed by the cell main body and the plate. A correlation cell, which is provided in the cell body, to which the plate member is attached, and a plurality of communication paths which are provided in the cell body corresponding to each of the plurality of gas chambers and communicate with the gas chamber; A sealing member that is inserted into each of the plurality of communication passages and hermetically seals the communication passage, and the position of the end of the sealing member close to the gas chamber communicating with the communication passage is In addition, the position is farther from the gas chamber than the position of the end portion of the mounting surface in the length direction of the communication path.

  Here, a female screw is formed in each of the plurality of communication paths, and a male screw corresponding to the female screw is formed in the sealing member. Further, the sealing member has a screw head having a diameter larger than that of the male screw, and the sealing member is positioned with respect to the cell main body by engaging the screw head with the cell main body. Can be characterized. The cell body may include a concave counterbore portion that receives the screw head of the sealing member.

  From another point of view, a gas analyzer to which the present invention is applied is a gas analyzer that analyzes a sample gas using an infrared absorption method of a gas correlation method, and includes a light source that emits infrared light, and the light source. And a cell pipe into which the sample gas is introduced, a cell main body and a translucent plate attached to the cell main body, and a plurality of gas chambers are formed by the cell main body and the plate material. Correlation cell arranged to transmit infrared light before being incident on the cell pipe, a drive source for rotationally driving the correlation cell, and receiving infrared light incident on the cell pipe to correspond to the amount of the infrared light The correlation cell is provided in the cell body corresponding to each of the plurality of gas chambers, and a plurality of communication passages communicating with the gas chambers; A sealing member that is inserted into each of the plurality of communication paths and hermetically seals the communication path, and the position of the end of the sealing member close to the gas chamber communicating with the communication path is The position is farther from the gas chamber than the position of the end portion of the plate member in the length direction of the communication path.

  Here, a female screw is formed in each of the plurality of communication paths, and a male screw corresponding to the female screw is formed in the sealing member.

  Further, from another viewpoint, the method for assembling a correlation cell to which the present invention is applied is provided with a plurality of gas chambers corresponding to each of the plurality of gas chambers and communicates with the gas chambers. A method for assembling a correlation cell, wherein a plate body is fixed to a cell body having a plurality of communication paths and a mounting surface to which a plate material for partitioning the gas chamber is attached, and is engaged with the inner surface of the communication path. In addition, a sealing member is inserted so as not to reach the position of the communication path corresponding to the position of the end of the mounting surface, the communication path is hermetically closed, distortion of the mounting surface is removed, and the plate material is removed. It fixes to the said attachment surface, It is characterized by the above-mentioned.

  Here, a female screw is formed in each of the plurality of communication passages, and the sealing member has a male screw portion in which a male screw corresponding to the female screw is formed.

  According to the present invention, it is possible to suppress the occurrence of gas leakage after the gas is sealed.

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.
FIG.1 and FIG.2 is a schematic block diagram which shows the gas analyzer 1 which concerns on this Embodiment. 1 is a cross-sectional view of the gas analyzer 1 as viewed from the upper side, and FIG. 2A is a vertical cross-sectional view of the gas analyzer 1 as viewed from the sample gas outlet 23 side. ) Is a side view of the gas analyzer 1 as viewed from the multiple reflection mirror 25 side. In FIG. 1 and FIG. 2A, the optical path of the infrared light is indicated by a broken line.
As shown in FIGS. 1 and 2, the gas analyzer 1 measures a gas concentration by a gas correlation method, and an infrared light source 11 that emits (irradiates) infrared light, and infrared light from the infrared light source 11 is received. The incident cell pipe 2 and the outer shape arranged on the optical path of the infrared light between the infrared light source 11 and the cell pipe 2 are positioned between the correlation cell 3 having a disk shape, and between the correlation cell 3 and the cell pipe 2 and correlated. A chopper 12 attached to the cell 3, a motor 13 for generating a driving force for rotating the correlation cell 3 and the chopper 12 at a constant speed, and infrared light incident on the cell pipe 2 are received and converted into electrical signals. An infrared photodetector 14.

  The cell pipe 2 includes an internal space 21, a sample gas inlet 22 for introducing a sample gas (sample, measurement target gas) into the internal space 21, a sample gas outlet 23 for discharging the sample gas in the internal space 21, It has. That is, the sample gas continuously introduced from the sample gas inlet 22 passes through the internal space 21 and is continuously exhausted from the sample gas outlet 23. An example of the sample gas mentioned here includes atmospheric gas for continuously measuring the carbon monoxide concentration in the atmosphere.

  The cell pipe 2 includes a plurality of reflecting surfaces arranged in the internal space 21 so that the directivity of infrared light is maintained. Specifically, the cell pipe 2 includes a reflection mirror 24 that changes the optical path of infrared light that passes through the chopper 12 and is incident on the internal space 21, and two multiple reflection mirrors 25 and 26 that are arranged to face each other. And a reflection mirror 27 that changes the optical path so that infrared light, which is sequentially reflected by the two multiple reflection mirrors 25 and 26, is finally directed to the infrared light detector 14.

  More specifically, since the infrared light incident on the internal space 21 is absorbed by the sample gas before being emitted from the internal space 21, the gas in the sample gas is detected by detecting the degree of attenuation of the amount of infrared light. The concentration is measured. For this reason, if a long optical path length is secured, the measurement accuracy can be increased accordingly. As described above, the cell pipe 2 in the present embodiment adopts a configuration in which the interior space 21 is reflected a plurality of times, so that the optical path length can be increased while making the outer shape of the cell pipe 2 compact. It is possible to reduce the size of the gas analyzer 1.

  The correlation cell 3 in the present embodiment is compared with a measurement gas chamber (measurement target gas chamber) 42 (see FIG. 4) in which a gas of the same type as the measurement target gas having a predetermined concentration is sealed, and inactive to infrared rays. And a comparison gas chamber 43 (see FIG. 4) in which the target gas is sealed. A specific structure of the correlation cell 3 will be described later.

  The chopper 12 is provided for chopping infrared light and introducing it into the cell pipe 2 in order to reduce noise, and has a plurality of slits (not shown) for interrupting the infrared light.

The motor 13 is controlled by a control unit (not shown), and a coupling (rotary shaft) 15 is fixedly attached to the output shaft. For this reason, the driving force of the motor 13 is transmitted from the output shaft to the correlation cell 3 via the coupling (rotating shaft) 15. Thereby, the correlation cell 3 rotates in one direction with the chopper 12 at a constant speed. In other words, the infrared light emitted from the infrared light source 11 enters the cell pipe 2 when it is allowed to pass by the chopper 12 after passing through the correlation cell 3.
A cover 16 that covers the coupling 15, the infrared light source 11, the correlation cell 3, and the chopper 12 is disposed between the motor 13 and the cell pipe 2. The cover 16 is illustrated by a one-dot chain line in FIG. 1, and is illustrated by a solid line in FIG.

  The infrared photodetector 14 is mounted on the printed circuit board 18 via the holder member 17. The printed circuit board 18 is disposed in the cover 19, thereby blocking light from the outside. The infrared light detector 14 may be composed of an element having sensitivity to infrared light, such as a PbSe element.

  In the gas analyzer 1 according to the present embodiment, the infrared light from the infrared light source 11 passes through the correlation cell 3 and the chopper 12 and then enters the infrared light detector 14 through the cell pipe 2 and is proportional to the amount of light. Converted to a signal. Thereby, the measurement object gas concentration in sample gas can be calculated | required by predetermined | prescribed calculation.

FIG. 3 is a schematic configuration diagram of the correlation cell 3.
As shown in FIG. 3, the correlation cell 3 includes a wheel 4 as a cell body, a window plate 5 as a translucent plate adhered (fixed) to both surfaces of the wheel 4 with an adhesive, And a screw member 6 having a male screw portion 63 corresponding to the female screw formed in the communication path 44.
The wheel 4 is made of a material having a coefficient of thermal expansion close to that of sapphire (for example, Kovar) near room temperature, the window plate 5 is made of sapphire, and the screw member 6 is made of stainless steel.

  The window plate 5 is a plate material having a predetermined thickness, and has a through hole 51 in the center. The through hole 51 has a shape corresponding to the rotation hole 41 of the wheel 4. The window plate 5 is formed in a circular shape and has an end 52 as an outer peripheral surface. The outer diameter of the window plate 5 is substantially the same as the outer diameter of the mounting surface 46 of the wheel 4. The front and back surfaces of the window plate 5 are formed flat.

The screw member 6 includes a male screw portion 63, an end portion 61 that is a tip of the male screw portion 63, and a screw head 62 having a larger diameter than the male screw portion 63. In other words, one end of the screw member 6 is the end portion 61 and the other end is the screw head 62. More specifically, the screw member 6 is screwed into the communication path 44, thereby closing the communication path 44. For this reason, when the screw member 6 is used, the communication path 44 can be hermetically sealed. Therefore, it can be said that the screw member 6 is a sealing member or a sealing member.
In other words, when the screw member 6 is screwed into the communication passage 44, the end portion 61 is located on the farthest side (the side close to the measurement gas chamber 42 or the comparison gas chamber 43). Moreover, in this Embodiment, the screw member 6 as a sealing member is being fixed to the communicating path 44 of the wheel 4 by screw fastening.

  Here, the relative positional relationship between the wheel 4 and the screw member 6 will be described. With respect to the length direction of the communication path 44 of the wheel 4 (left and right direction in FIG. 3, radial direction of the wheel 4), the position of the end portion 47 of the wheel 4 is larger than the position of the end portion 61 of the screw member 6. Or it is close to the comparison gas chamber 43. In other words, the end 61 of the screw member 6 is located farther from the measurement gas chamber 42 or the comparison gas chamber 43 than the position of the end 47 of the wheel 4. Note that the relative positions of the end 47 of the wheel 4 and the end 52 of the window plate 5 are substantially the same.

  More specifically, the end portion 47 of the wheel 4 and the end portion 61 of the screw member 6 are separated from each other with respect to the length direction of the communication path 44 of the wheel 4. That is, the end portion 47 and the end portion 61 are separated by a distance δ.

  As described above, in this embodiment, when the screw member 6 is screwed into the correlation cell 3, the end surface 61 of the screw member 6 adheres the wheel 4 and the window plate 5 to each other (attachment surface 46). Adopted a structure that does not reach. Therefore, when the screw 4 is stressed by tightening the screw member 6 in the communication path 44 of the wheel 4, the influence of the stress on the mounting surface 46 of the wheel 4 is reduced. For this reason, generation | occurrence | production of the distortion of the adhesion surface accompanying screwing the screw member 6 to the wheel 4 can be prevented.

4A and 4B are diagrams for explaining the wheel 4, in which FIG. 4A is a front view, and FIG. 4B is a cross-sectional view taken along line IVb-IVb in FIG.
As shown in FIGS. 4A and 4B, the wheel 4 has a disk shape with a predetermined thickness, and has a rotation hole 41 extending in the thickness direction at the center. Further, the wheel 4 has a measurement gas chamber 42 and a comparison gas chamber 43 that are positioned around the rotation hole 41. That is, the measurement gas chamber 42 and the comparison gas chamber 43 are located between the outer peripheral surface 4 a and the rotation hole 41. The measurement gas chamber 42 and the comparison gas chamber 43 have the same shape, and the positional relationship with respect to the rotation hole 41 is the same.

The wheel 4 has two communication paths 44 extending radially from the outer peripheral surface 4a. One of the two communication passages 44 communicates with the measurement gas chamber 42, and the other communicates with the comparison gas chamber 43. Each of these communication passages 44 is formed with a female screw. As described above, the internal thread of the communication path 44 corresponds to the external thread portion 63 (see FIG. 3 or 5) of the screw member 6.
A concave counterbore 45 is formed on the outer peripheral surface 4 a side of each communication passage 44. The counterbore 45 has an outer diameter that can receive the screw head 62 of the screw member 6.

  The wheel 4 has a mounting surface 46 formed substantially flat. The mounting surface 46 is formed to have a flatness higher than that of the other surface of the wheel 4. The attachment surface 46 is a surface (adhesion surface) to which the window plate 5 is attached with an adhesive.

  More specifically, when the window plate 5 is attached to the attachment surface 46 of the wheel 4, both sides of the measurement gas chamber 42 and the comparison gas chamber 43 are partitioned from the outside. As a result, the measurement gas chamber 42 and the comparison gas chamber 43 communicate with the outside via the communication path 44.

  The wheel 4 has a mounting hole 48 for mounting the chopper 12. The attachment hole 48 extends in the same direction as the rotation hole 41. The chopper 12 has a mounting hole (not shown) corresponding to the mounting hole 48 of the wheel 4.

FIG. 5 is an exploded perspective view for explaining a method of assembling the correlation cell 3.
In assembling the correlation cell 3, as shown in FIG. 5, a wheel 4, two window plates 5, and two screw members 6 are prepared. The wheel 4, the window plate 5, and the screw member 6 have the above-described structure.

  Here, the end portion 47 of the wheel 4 and the spot facing 45 are located apart from each other by a distance T in the radial direction. Further, the length of the male screw portion 63 of the screw member 6 is the length S. In other words, the distance δ shown in FIG. 3 is a value obtained by subtracting the length S from the distance T. That is, δ = T−S.

  As a procedure for assembling the correlation cell 3, first, the screw member 6 is tightened in the communication path 44 of the wheel 4, and then a finishing process for the mounting surface 46 of the wheel 4 is started. Although the mounting surface 46 is processed and flattened with high accuracy, a case in which distortion occurs due to tightening of the screw member 6 is assumed. More specifically, even if the screw member 6 is tightened in the communication passage 44 of the wheel 4, the end 61 of the screw member 6 does not reach the end 47 of the mounting surface 46, so that the occurrence of distortion is suppressed. However, it cannot always be said that no distortion occurs. If such distortion occurs, if the window plate 5 is adhered to the mounting surface 46 of the wheel 4 with the distortion remaining, gas leakage may occur after gas filling. The finishing process is an operation for producing a highly airtight correlation cell by removing the distortion of the mounting surface 46 generated in this way, thereby preventing gas leakage after gas filling.

  More specifically, in the finishing step, the mounting surface 46 is polished with, for example, water-resistant paper in a state where the screw member 6 is fastened to the wheel 4. Thus, even if the mounting surface 46 is distorted by finishing the mounting surface 46 after the screw member 6 is tightened in advance in the communication passage 44 as a gas filling port, the window plate 5 is attached to the mounting surface 46. It is possible to remove the distortion of the mounting surface 46 at a stage before bonding. Whether or not the distortion of the attachment surface 46 has been removed can be determined by whether or not interference fringes due to the adhesive are observed on the attachment surface 46 in the vicinity of the communication path 44 by visual observation.

  After finishing the finishing process, for example, an adhesive of UV curable resin is applied to the mounting surface 46 of the wheel 4, and the window plate 5 is attached to the mounting surface 46 and irradiated with ultraviolet rays, so that the window plate 5 is bonded to the wheel 4. To do. Thereby, the assembly of the correlation cell 3 is completed.

In other words, the gas filling step is performed after the assembly of the correlation cell 3 is completed. In this gas filling step, first, the screw member 6 is removed from the wheel 4 using a tool. Then, after filling the measurement gas chamber 42 of the correlation cell 3 from the communication path 44 with the measurement target gas, the screw member 6 is tightened into the communication path 44. As a result, the measurement target gas is sealed in the measurement gas chamber 42. In addition, when tightening the screw member 6 at the time of sealing, it is preferable that the tightening torque be a predetermined value.
Similarly, after the comparison gas chamber 43 of the correlation cell 3 is filled with the comparison gas from the communication path 44, the screw member 6 is tightened into the communication path 44 and the comparison gas is sealed in the comparison gas chamber 43. After the screw member 6 is tightened, for example, an ultraviolet curable resin adhesive is filled in the counterbore 45 of the wheel 4. Thereby, loosening of the screw member 6 can be prevented. In addition, such a gas filling process is performed in a dedicated container.

  The gas analyzer 1 according to the present embodiment can be incorporated into a measuring device that continuously measures the carbon monoxide (CO) concentration in the atmosphere, for example. This atmospheric carbon monoxide measuring device is mainly used for continuous monitoring and environmental assessment (environmental impact assessment) by the Air Pollution Control Act, and the measurement data is sent to an observation station (central monitoring center) via a telemeter. There is a case in which a configuration for transmitting or transmitting / receiving various input / output signals via a telemeter may be employed. In this atmospheric carbon monoxide measuring apparatus, atmospheric gas containing carbon monoxide is used as a sample gas, but various processes are performed before introduction into the cell pipe 2. Specifically, it is a process of removing dust contained in the atmospheric gas with a filter or removing moisture that absorbs infrared light with a perm pure dryer.

It is a schematic block diagram which shows the gas analyzer which concerns on this Embodiment. It is a schematic block diagram which shows the gas analyzer which concerns on this Embodiment. It is a schematic block diagram of a correlation cell. It is a figure explaining a wheel, (a) is a front view, (b) is a sectional view by line IVb-IVb of (a). It is a disassembled perspective view for demonstrating the assembly method of a correlation cell.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Gas analyzer, 11 ... Infrared light source, 12 ... Chopper, 13 ... Motor, 14 ... Infrared photodetector, 15 ... Coupling, 16, 19 ... Cover, 17 ... Holder member, 18 ... Printed circuit board, 2 ... Cell pipe 21 ... Internal space, 22 ... Sample gas inlet, 23 ... Sample gas outlet, 24,27 ... Reflection mirror, 25,26 ... Multi-reflection mirror, 3 ... Correlation cell, 4 ... Wheel, 4a ... Outer peripheral surface, 41 ... Rotation Hole, 42 ... Measurement gas chamber, 43 ... Comparison gas chamber, 44 ... Communication passage, 45 ... Spot face, 46 ... Mounting surface, 47, 52, 61 ... End, 48 ... Mounting hole, 5 ... Window plate, 51 ... Through hole, 6 ... screw member, 62 ... screw head, 63 ... male screw part, S ... length, T ... distance, δ ... distance

Claims (8)

A correlation cell including a cell body and a translucent plate attached to the cell body, wherein a plurality of gas chambers are formed by the cell body and the plate,
A mounting surface provided on the cell body, to which the plate member is attached;
A plurality of communication passages provided in the cell body corresponding to each of the plurality of gas chambers, and communicating with the gas chambers;
A sealing member that is inserted into each of the plurality of communication paths and hermetically seals the communication path;
Including
The position of the end of the sealing member close to the gas chamber communicating with the communication path is farther from the gas chamber than the position of the end of the mounting surface in the length direction of the communication path. Correlation cell. An internal thread is formed in each of the plurality of communication paths,
2. The correlation cell according to claim 1, wherein a male screw corresponding to the female screw is formed on the sealing member. The sealing member has a screw head having a larger diameter than the male screw,
The correlation cell according to claim 2, wherein the sealing member is positioned with respect to the cell body by engaging the screw head with the cell body.   The correlation cell according to claim 3, wherein the cell body has a concave counterbore portion that receives the screw head of the sealing member. A gas analyzer for analyzing a sample gas using an infrared absorption method of a gas correlation method,
A light source that emits infrared light;
A cell pipe into which the light source is incident and sample gas is introduced;
A plurality of gas chambers are formed by the cell body and the plate material, and infrared light from the light source is transmitted before entering the cell pipe. Correlation cells arranged as follows:
A drive source for rotationally driving the correlation cell;
A detector that receives the infrared light incident on the cell pipe and converts it into an electrical signal corresponding to the amount of the infrared light; and
Including
The correlation cell is
A plurality of communication passages provided in the cell body corresponding to each of the plurality of gas chambers, and communicating with the gas chambers;
A sealing member that is inserted into each of the plurality of communication paths and hermetically seals the communication path;
Including
The gas is characterized in that the position of the end of the sealing member close to the gas chamber communicating with the communication path is farther from the gas chamber than the position of the end of the plate member in the length direction of the communication path. Analysis equipment. An internal thread is formed in each of the plurality of communication paths,
The gas analyzer according to claim 5, wherein the sealing member is formed with a male screw corresponding to the female screw. A cell body having a plurality of gas chambers, a plurality of communication passages provided corresponding to each of the plurality of gas chambers and communicating with the gas chambers, and a mounting surface to which a plate material for partitioning the gas chambers is attached A method of assembling a correlation cell in which the plate material is fixed to
Engaging the inner surface of the communication path and inserting a sealing member so as not to reach the position of the communication path corresponding to the position of the end portion of the mounting surface, and the communication path is hermetically closed;
Removing distortion of the mounting surface;
A method of assembling a correlation cell, wherein the plate material is fixed to the mounting surface. An internal thread is formed in each of the plurality of communication paths,
8. The correlation cell assembling method according to claim 7, wherein the sealing member has a male screw portion in which a male screw corresponding to the female screw is formed.

Images