Detector for infrared gas analyzer

Abstract

To improve work efficiency during manufacturing and maintain good sensitivity over the long term. [Solution] The infrared gas analyzer detector (20) comprises first to fourth infrared transmitting windows (21 to 24) that transmit infrared rays, a front gas chamber forming body (27) and a rear gas chamber forming body (28) to which the infrared transmitting windows are joined to form first to third gas chambers (31, 32, 49), and a sensor unit (60) housed in a containment space (62) communicating with each gas chamber to detect the concentration of the gas to be measured. The gas chamber forming body comprises a frame (35a to 35c, 52) to which the first to fourth infrared transmitting windows are joined, and a main body (34, 51) that forms each gas chamber and to which the first to fourth frame (34 to 51) is joined. Each infrared transmitting window is joined to the frame via a joining member (45 to 48) which is made of low melting point glass.

Description

Technical Field

[0001] The present invention relates to a detector for an infrared gas analyzer.

Background Art

[0002] Patent Document 1 discloses an infrared gas analyzer including a detection unit that measures the concentration of a gas to be measured. The detection unit includes a flow sensor that detects a pressure difference between a front chamber and a rear chamber in a communication passage that connects the front chamber and the rear chamber. Further, the detection unit includes a front block that forms the front chamber and a rear block that forms the rear chamber, and both front and rear ends of the front block and the rear end of the rear block are sealed with window plates that transmit infrared light.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In Patent Document 1, an epoxy resin-based adhesive is used for joining the window plates to each block and for joining the blocks to each other. For this reason, not only does the time for maintaining the adhesive at a high temperature become longer for joining, but also degassing is released from the adhesive into the front chamber and the rear chamber, resulting in a longer aging time and a decrease in workability during manufacturing. Further, the epoxy resin-based adhesive adsorbs the sensing gas such as SO2 sealed in the front chamber and the rear chamber, and a problem of sensitivity degradation occurs due to deterioration over time.

[0005] The present invention has been made in view of such circumstances, and an object thereof is to provide a detector for an infrared gas analyzer that can improve workability during manufacturing and maintain good sensitivity over a long period of time.

Means for Solving the Problems

[0006] An infrared gas analyzer detector according to one aspect of the present invention is an infrared gas analyzer detector capable of detecting the concentration of a gas to be measured, comprising: an infrared transmission window that transmits infrared rays; a plurality of gas chamber forming bodies that form gas chambers in which the infrared transmission windows are joined and in which the gas components to be measured are sealed; and a sensor unit that is housed in a containment space that is formed in each of the plurality of gas chamber forming bodies and communicates with the gas chambers, and detects the concentration of the gas to be measured by detecting the gas flow generated in the containment space, wherein the gas chamber forming body comprises a frame to which the infrared transmission window is joined, and a main body that forms the gas chamber and to which the frame is joined, The frame and the main body are joined together by welding using light energy. The infrared-transmitting window is joined to the frame via a joining member, and the joining member is made of low-melting-point glass. The gas chamber forming bodies are joined together by low-melting-point glass with a lower melting point than the low-melting-point glass used for the joining member. It is characterized by the following.

[0007] An infrared gas analyzer detector according to one aspect of the present invention is an infrared gas analyzer detector capable of detecting the concentration of a gas to be measured, comprising: an infrared transmission window that transmits infrared rays; a plurality of gas chamber forming bodies that form gas chambers in which the infrared transmission windows are joined and in which the gas components to be measured are sealed; and a sensor unit that is housed in a containment space that is formed in each of the plurality of gas chamber forming bodies and communicates with the gas chambers, and detects the concentration of the gas to be measured by detecting the gas flow generated in the containment space, wherein the gas chamber forming body comprises a frame to which the infrared transmission window is joined, and a main body that forms the gas chamber and to which the frame is joined, The frame and the main body are joined together by welding using light energy. The metal layers formed in the joint regions of the infrared-transmitting window and the frame are joined via solder members that serve as joining members. The gas chamber forming bodies are joined together by a soldering agent having a lower melting point than the soldering agent used for the joining member. It is characterized by the following. [Effects of the Invention]

[0014] According to the present invention, since no organic adhesives such as epoxy resins are used at the joints, the workability during manufacturing can be improved, and good sensitivity can be maintained over a long period of time. [Brief explanation of the drawing]

[0015] [Figure 1]This is a cross-sectional view of an infrared gas analyzer according to the first embodiment. [Figure 2] This is a cross-sectional view of a detector for an infrared gas analyzer according to the first embodiment. [Figure 3] This is a cross-sectional view of a detector for an infrared gas analyzer according to a second embodiment. [Modes for carrying out the invention]

[0016] The infrared gas analyzer including a detector for an infrared gas analyzer according to an embodiment of the present invention will be described in detail below with reference to the attached drawings. Note that the present invention is not limited to the embodiments described below, and can be modified as appropriate without changing its essence. In the following figures, some components may be omitted for the sake of explanation. Also, in the following description, unless otherwise specified, "front" and "back" refer to the direction indicated by the arrows in each figure. However, the orientation of each component is merely an example and can be changed to any orientation.

[0017] The infrared gas analyzers in the embodiments described below measure the concentration of gas molecules by utilizing the properties of gas molecules (gas components). Generally, gas molecules composed of two or more different atoms have their own unique vibrational and rotational energies. When gas molecules are irradiated with infrared light at wavelengths corresponding to the spectrum of their unique vibration and rotation, they are excited and absorb the corresponding specific infrared light. This property is used to measure (detect) the gas concentration using the infrared light after absorption.

[0018] [First Embodiment] Figure 1 is a cross-sectional view of an infrared gas analyzer 1 according to a first embodiment. As shown in Figure 1, the infrared gas analyzer 1 is configured to include a light source unit 2, an optical chopper 6, a sample cell 9, and an infrared gas analyzer detector 20.

[0019] The light source unit 2 comprises a light source chamber 3, an infrared light source 4, and a window plate 5 that serves as an infrared-transmitting window, and is located on one end of the sample cell 9. The infrared light source 4 is placed inside the light source chamber 3, and power is supplied to the infrared light source 4 from a connected power supply, causing it to generate heat and emit infrared radiation corresponding to its temperature. The infrared radiation passes through the window plate 5, which is positioned in the direction of infrared radiation, through the optical chopper 6, and is irradiated into the interior of the sample cell 9.

[0020] The optical chopper 6 consists of a rotating disk 7 and a motor 8. The rotating disk 7 is driven to rotate by the motor 8 and is positioned to rotate between the light source unit 2 and the sample cell 9. The rotating disk 7 also has an opening or notch that allows infrared rays to pass through. When the rotating disk 7 rotates, the opening or notch turns the infrared rays emitted from the light source unit 2 on and off at a predetermined interval, thereby intermittently irradiating the sample cell 9 with infrared rays.

[0021] The sample cell 9 comprises a cell body 10, sample gas inlets and outlets 11 and 12, and window plates 13 and 14 that serve as infrared-transmitting windows. The cell body 10 is cylindrical and made of a corrosion-resistant metal material such as stainless steel. The window plates 13 and 14 are made of an infrared-transmitting material such as CaF2 and are fixed to both ends of the cell body 10 to seal them. Sample gas is introduced from one of the sample gas inlets and outlets 11 and 12 and exited from the other. An infrared gas analyzer detector 20 is located at the other end of the sample cell 9 (opposite the light source unit 2).

[0022] Figure 2 is a cross-sectional view of the infrared gas analyzer detector 20 according to the first embodiment. As shown in Figure 2, the infrared gas analyzer detector 20 includes first to fourth infrared transmitting windows 21 to 24 (infrared transmitting windows) that transmit infrared rays, a front gas chamber forming body 27 to which the first to third infrared transmitting windows 21 to 23 are joined, and a rear gas chamber forming body 28 to which the fourth infrared transmitting window 24 is joined. Therefore, the infrared gas analyzer detector 20 has two (or more) gas chamber forming bodies, consisting of the front gas chamber forming body 27 and the rear gas chamber forming body 28.

[0023] In the detector 20 for an infrared gas analyzer, first to fourth infrared transmission windows 21 to 24 are arranged in parallel in order from the front side (the light source unit 2 side) toward the rear side. Each of the infrared transmission windows 21 to 24 is made of an infrared transmission material, for example, like the above-described window plates 13 and 14, and may be not only fluoride glass such as CaF2 but also other materials that transmit infrared rays. Each of the infrared transmission windows 21 to 24 is formed in a plate shape that is circular when viewed from the front-rear direction.

[0024] The front gas chamber forming body 27 and the rear gas chamber forming body 28 are constituted by processing a columnar block made of an aluminum alloy. Note that the front gas chamber forming body 27 and the rear gas chamber forming body 28 may be made of a metal other than an aluminum alloy, such as stainless steel or copper.

[0025] The front gas chamber forming body 27 forms a first gas chamber 31 and a second gas chamber 32 in order from the front side as two gas chambers. The front gas chamber forming body 27 also includes a cylindrical main body part 34 that forms the main part of the front gas chamber forming body 27, and three annular frame bodies 35a to 35c interposed between the main body part 34 and the first to third infrared transmission windows 21 to 23.

[0026] The main body part 34 of the front gas chamber forming body 27 is provided in a shape having a round-hole-shaped through hole centered on the center of the above-described columnar block or a recess formed by counterboring. Specifically, the front gas chamber forming body 27 includes a front receiving part 37 formed by recessing the front end face of the main body part 34, a stepped hole 38 penetrating the main body part 34, and a rear receiving part 39 formed by recessing the rear end face of the main body part 34. The front gas chamber forming body 27 also has a first seating surface 41 formed by the bottom surface (the lower surface in FIG. 2) of the front receiving part 37, a second seating surface 42 formed at the step part of the stepped hole 38, and a third seating surface 43 formed by the bottom surface (the upper surface in FIG. 2) of the rear receiving part 39. Each of the seating surfaces 41 to 43 is directed in a direction orthogonal to the front-rear direction. A diameter-expanded part 40 is formed continuous to the second seating surface 42.

[0027] The first infrared transmission window 21 is joined to the annular frame 35a at its outer peripheral side and outer peripheral bottom surface via a joining member 45, and the first infrared transmission window 21 and the frame 35a are formed as one unit. The frame 35a joined with the first infrared transmission window 21 is received in the front receiving portion 37 in a state of abutting against the first seating surface 41 so that no gap is generated. In other words, the outer peripheral shape of the frame 35a and the inner peripheral shape of the front receiving portion 37 are formed so that the frame 35a can be received in the front receiving portion 37 without a gap. The joining member 45 will be described later.

[0028] At the front end face of the main body portion 34, the frame 35a is joined to the main body portion 34 by laser welding across the boundary between the front receiving portion 37 and the frame 35a. For example, when viewed in the front-rear direction, the boundary between the front receiving portion 37 and the frame 35a呈 circular loop shape, and it is joined by continuously laser welding all of such loop-shaped boundaries. In this state, the first infrared transmission window 21 is joined to the main body portion 34 of the front gas chamber forming body 27 via the joining member 45 and the frame 35a.

[0029] The second infrared transmission window 22 is joined to the annular frame 35a at its outer peripheral side and outer peripheral bottom surface via a joining member 46, and the second infrared transmission window 22 and the frame 35b are formed as one unit. The frame 35b joined with the second infrared transmission window 22 is received in the diameter-expanded portion 40 in a state of abutting against the second seating surface 42 so that no gap is generated. In other words, the outer peripheral shape of the frame 35b and the inner peripheral shape of the diameter-expanded portion 40 are formed so that the frame 35b can be received in the diameter-expanded portion 40 without a gap. The joining member 46 will be described later.

[0030] At the stepped hole 38 of the main body portion 34, the frame 35b is joined to the main body portion 34 by laser welding across the boundary between the diameter-expanded portion 40 and the frame 35b. For example, the boundary between the diameter-expanded portion 40 and the frame 35b呈 loop shape parallel to the inner periphery of the stepped hole 38, and it is joined by continuously laser welding all of such loop-shaped boundaries. In this state, the second infrared transmission window 22 is joined to the main body portion 34 of the front gas chamber forming body 27 via the joining member 46 and the frame 35b.

[0031] The first infrared-transmitting window 21 and the second infrared-transmitting window 22 are joined together via the joining members 45, 46 and the frames 35a, 35b, thereby forming a first gas chamber 31 that is closed off by the main body 34, the frames 35a, 35b, the first infrared-transmitting window 21, and the second infrared-transmitting window 22.

[0032] The third infrared-transmitting window 23 is joined to an annular frame 35c via a joining member 47 on its outer circumference and outer bottom surface, so that the third infrared-transmitting window 23 and the frame 35c are formed as a single unit. The frame 35c to which the third infrared-transmitting window 23 is joined is received in the rear receiving portion 39 without any gaps when it is in contact with the third seating surface 43. In other words, the outer circumference shape of the frame 35c and the inner circumference shape of the rear receiving portion 39 are formed so that the frame 35c can be received in the rear receiving portion 39 without any gaps.

[0033] The frame 35c is joined to the main body 34 by laser welding across the boundary between the rear receiving portion 39 and the frame 35c at the rear end surface of the main body 34. For example, when viewed from the front-rear direction, the boundary between the rear receiving portion 39 and the frame 35c has a circular loop shape, and the entire loop-shaped boundary is joined by continuous laser welding. In this state, the third infrared-transmitting window 23 is joined to the main body 34 of the front gas chamber forming body 27 via the joining member 47 and the frame 35c. Through this joining and the joining of the second infrared-transmitting window 22 described above, the second gas chamber 32 is formed, which is closed by the main body 34, the frame 35c, the second infrared-transmitting window 22 and the third infrared-transmitting window 23.

[0034] Furthermore, when performing laser welding, it is preferable to select a 3000 series aluminum alloy (e.g., A3003) with good workability, including weldability, for the aluminum alloy used for the main body 34 and each frame 35a to 35c, by adding Mn.

[0035] The rear gas chamber forming body 28 forms one third gas chamber 49 (gas chamber). The rear gas chamber forming body 28 also comprises a main body portion 51 formed to have the same outer diameter as the front gas chamber forming body 27, and an annular frame 52 interposed between the main body portion 51 and the fourth infrared-transmitting window 24.

[0036] The rear gas chamber forming body 28 is formed by a stepped recess created by recessing the front end surface of the main body portion 51. The rear gas chamber forming body 28 includes a large-diameter recess 54 at the front, a small-diameter recess 55 at the rear, and a fourth seating surface 56 formed in the stepped portion. The fourth seating surface 56 is oriented in a direction perpendicular to the front-rear direction.

[0037] The fourth infrared-transmitting window 24 is joined to an annular frame 52 via a joining member 48 on its outer circumference and outer bottom surface, so that the fourth infrared-transmitting window 24 and the frame 52 are formed as a single unit. The frame 52 to which the fourth infrared-transmitting window 24 is joined is received in the large-diameter recess 54 without any gaps when it is in contact with the fourth seat surface 56. In other words, the outer circumference shape of the frame 52 and the inner circumference shape of the large-diameter recess 54 are formed so that the frame 52 can be received in the large-diameter recess 54 without any gaps.

[0038] The frame 52 is joined to the main body 51 of the rear gas chamber forming body 28 by laser welding across the boundary between the large-diameter recess 54 and the frame 52 at the rear end surface of the main body 51. For example, when viewed from the front-rear direction, the boundary between the large-diameter recess 54 and the frame 52 has a circular loop shape, and the entire loop-shaped boundary is joined by continuous laser welding. In this state, the fourth infrared-transmitting window 24 is joined to the main body 51 of the rear gas chamber forming body 28 via the joining member 48 and the frame 52, and a closed third gas chamber 49 is formed by the main body 51, the frame 52 and the fourth infrared-transmitting window 23.

[0039] Each joining member 45-48 is made of low-melting-point glass, which has a lower melting point than ordinary glass. Low-melting-point glass is a glassy inorganic material and is formed by placing glass frit, which is the material to be joined, in the area where each infrared-transmitting window 21-24 is joined, heating it to its softening point, and then hardening it. The chemical properties of the low-melting-point glass may be selected according to the gas sealed in each gas chamber 31, 32, and 49.

[0040] Each joining member 45-48 is provided so as to be sandwiched between the upper surface of frame 35a, the upper surface of frame 35b, the lower surface of frame 35c, and the upper surface of frame 52, which are the areas where each infrared-transmitting window 21-24 is joined, thereby ensuring the sealing (airtightness) of each gas chamber 31, 32, and 49. Furthermore, each joining member 45-48 is also provided on the outer peripheral surface and outer peripheral bottom surface of each infrared-transmitting window 21-24, and is provided so as to fill the space between each frame 35a-35c and 52, thereby providing better sealing of each gas chamber 31, 32, and 49.

[0041] The rear side of the front gas chamber forming body 27 and the front side of the rear gas chamber forming body 28 are joined by low-melting-point glass 58. The melting point of this low-melting-point glass 58 is set lower than that of the low-melting-point glass used for each joining member 45-48. By setting the melting point in this way, when the gas chamber forming bodies 27 and 28 are joined together with the low-melting-point glass 58 after the infrared-transmitting windows 21-24 have been joined by each joining member 45-48, it is possible to avoid the joining members 45-48 softening.

[0042] Here, the infrared gas analyzer detector 20 includes a sensor unit 60 (mass flow sensor). The sensor unit 60 is housed in a housing space 62 formed on the side of the front gas chamber forming body 27. The sensor unit 60 is connected to a hermetic terminal 63, which is inserted into the housing space 62 from the outer surface of the front gas chamber forming body 27. The hermetic terminal 63 is provided with a lead pin made of a conductive material, which outputs the signal detected by the sensor unit 60 to the outside.

[0043] The sensor unit 60 and the first gas chamber 31 are connected by a first passage 65 formed in the front gas chamber forming body 27. The sensor unit 60 and the second gas chamber 32 are connected by a second passage 66 formed in the front gas chamber forming body 27 and the hermetic terminal 63. The sensor unit 60 and the third gas chamber 49 are connected by a third passage 67 formed in the front gas chamber forming body 27 and the rear gas chamber forming body 28. Low melting point glass 58 is not formed in the portion where the third passage 67 is formed.

[0044] In this embodiment, infrared light is emitted from the light source unit 2, passes through the sample cell 9, and is incident on the infrared gas analyzer detector 20. The infrared light incident on the sample cell 9 is partially absorbed according to the concentration of the gas component to be measured in the gas to be measured, and the remaining infrared light is incident on the infrared gas analyzer detector 20.

[0045] The first gas chamber 31, second gas chamber 32, and third gas chamber 49 of the infrared gas analyzer detector 20 are sealed with the gas component to be measured. Most of the incident infrared radiation is absorbed in the first gas chamber 31, and the remainder is absorbed in the second gas chamber 32 and third gas chamber 49. At this time, volume expansion proportional to the amount of infrared radiation absorbed occurs, creating a pressure difference in each gas chamber 31, 32, and 49. This generates a minute gas flow inside the containment space 62 and each passage 65-67 that connects each gas chamber 31, 32, and 49. The sensor unit 60 can detect the pressure or flow rate change due to this gas flow as a change in resistance and convert it into an electrical signal to detect the concentration of the gas to be measured.

[0046] According to the first embodiment described above, since each joining member 45-48 is made of low-melting-point glass, the time required to maintain a high temperature during joining can be significantly reduced compared to organic adhesives such as epoxy resins, thereby improving workability. Furthermore, degassing is not released from each joining member 45-48 to each gas chamber 31, 32, and 49, eliminating the aging period that occurs when organic adhesives are used. Eliminating this aging period also improves workability and contributes to maintaining the sensitivity of the sensor unit 60 over a long period.

[0047] Furthermore, the gas sealed in each gas chamber 31, 32, and 49 is prevented from being adsorbed by the connecting members 45 to 48, thereby suppressing changes in the sealed gas over time and maintaining good sensitivity of the sensor unit 60 over a long period of time. Examples of gases that can be sealed in each gas chamber 31, 32, and 49 include CO2, CO, NO2, CH4, etc., and the adsorption of these gases can be avoided.

[0048] Furthermore, as described above, since each frame 35a to 35c and 52 is joined by laser welding, the occlusion of each gas chamber 31, 32, and 49 is ensured, eliminating the release of degassing substances like organic adhesives and the adsorption of enclosed gases at the joint, thereby maintaining good sensitivity of the sensor unit 60 over a long period. Moreover, the frames 35a to 35c and 52 and the first to fourth infrared transmission windows 21 to 24 can be joined as a single unit, and then the frames 35a to 35c and 52 can be joined by laser welding. This allows for a process of mass-producing the infrared gas analyzer detector 20, where many of these units are manufactured and then laser-welded together, improving work efficiency and reducing manufacturing time and costs during mass production. Note that the laser welding described above is welding using light energy, and other welding methods using light energy may be used as long as they can join the components in the same manner as in this embodiment.

[0049] [Second Embodiment] Next, a second embodiment of the present invention will be described. In the following description, the same reference numerals may be used for components that are the same as or equivalent to those in the first embodiment, and their descriptions may be omitted or simplified.

[0050] Figure 3 is a cross-sectional view of the infrared gas analyzer detector 80 according to the second embodiment. As shown in Figure 3, the second embodiment modifies the infrared gas analyzer detectors 20 and 80 compared to the first embodiment. More specifically, the infrared gas analyzer detector 80 of the second embodiment omits the rear gas chamber forming body 28 compared to the first embodiment, and the joining structure of the first to third infrared transmission windows 21 to 23 to the front gas chamber forming body 27 is modified. The sensor unit 60 and the various components used for detection in the sensor unit 60 in the first embodiment are the same in the second embodiment, but are omitted from the illustration in Figure 3.

[0051] As shown in Figure 3, the infrared gas analyzer detector 20 includes first to third frame bodies 81 to 83 (frames) that are joined to the main body 34. The first frame body 81 is joined to the outer periphery of the first infrared-transmitting window 21 at the front and to the first seat surface 41 at the rear. The second frame body 82 is joined to the outer periphery of the second infrared-transmitting window 22 at the front and to the second seat surface 42 at the rear. The third frame body 83 is joined to the outer periphery of the third infrared-transmitting window 23 at the rear and to the third seat surface 43 at the front.

[0052] The first to third frames 81 to 83 are formed in an annular shape and are similarly constructed except that their diameters differ according to the diameters of the first to third infrared-transmitting windows 21 to 23. Furthermore, the joining structure of the first infrared-transmitting window 21 and the first seat surface 41 to the first frame 81 is the same as the joining structure of the second infrared-transmitting window 22 and the second seat surface 42 to the second frame 82, and the joining structure of the third infrared-transmitting window 23 and the third seat surface 43 to the third frame 83. Therefore, in the following, only the joining structure of the first infrared-transmitting window 21 and the first seat surface 41 to the first frame 81 will be described, and the rest will be omitted.

[0053] The first infrared-transmitting window 21 and the first frame 81 are joined at room temperature via underlay layers 85, 87 and metal layers 86, 88 formed in their respective joining regions. Each of the layers 85-88 may be a vapor-deposited film manufactured by a vapor deposition method, and may be a chemically vapor-deposited film or a physically vapor-deposited film.

[0054] A base layer 85 is formed so as to be in direct contact with the joint area of ​​the first infrared-transmitting window 21, and a metal layer 86 is formed so as to be in direct contact with this base layer 85. A base layer 87 is formed so as to be in direct contact with the joint area of ​​the first frame 81, and a metal layer 88 is formed so as to be in direct contact with this base layer 87. The base layers 85, 87 and the metal layers 86, 88 are formed in an endless and closed loop shape (ring shape) along the outer circumference of the first infrared-transmitting window 21.

[0055] The base layers 85 and 87 ensure adhesion to the first infrared-transmitting window 21 and the first frame 81, and also ensure adhesion to the metal layers 86 and 88. Examples of base layers 85 and 87 include a Cr layer and a Ti layer. In the bonding region of the first frame 81, a planar treatment such as polishing is performed to ensure good adhesion with the base layer 87. The metal layers 86 and 88 are Al layers, but may also be Au layers.

[0056] The surface of the metal layer 86 provided in the first infrared-transmitting window 21 (bottom surface in Figure 3) and the surface of the metal layer 88 provided in the first frame 81 (top surface in Figure 3) are bonded at room temperature, with each surface becoming a bonded surface. Through this room-temperature bonding, the first infrared-transmitting window 21 and the first frame 81 become one unit, ensuring a closed seal between the first infrared-transmitting window 21 and the first frame 81.

[0057] Room temperature bonding involves, for example, activating the surface by removing the surface oxide film by argon (Ar) ion rimming at room temperature (e.g., around 25°C) under ultra-high vacuum at the bonding surface, and then directly bonding the metal layers 86 and 88 at room temperature. In room temperature bonding, the metal layers 86 and 88 may be pressurized. The term "room temperature bonding" is used to include surface activation bonding.

[0058] The joining surfaces of the metal layers 86 and 88 are subjected to a flattening treatment such as polishing to set the centerline average roughness Ra within a predetermined range. If the centerline average roughness Ra of the joining surfaces can be set within a predetermined range, the flattening treatment may be omitted.

[0059] The first frame 81 and the first seating surface 41 of the main body 34 are joined by ultrasonic bonding. To facilitate this ultrasonic bonding, a projection 89 is formed on the surface of the first frame 81 that is opposite to the first seating surface 41 (the lower surface in Figure 3). The projection 89 is an annular shape concentric with the first frame 81, and is formed in a closed loop shape and endlessly. The projection 89 has a triangular shape in cross-section perpendicular to the direction of extension, and is formed with a pointed tip.

[0060] Ultrasonic vibrations are applied to the tip of the protrusion 89 on the first frame 81 and the first seating surface 41 of the main body 34, thereby ultrasonic bonding. Ultrasonic bonding involves, for example, exposing a metal surface activated at the bonding portion by the application of ultrasound and bonding in a solid state by plastic deformation due to pressure. Through such ultrasonic bonding, the first frame 81 and the main body 34 become one unit, and a seal is ensured between the first frame 81 and the main body 34.

[0061] Furthermore, when performing ultrasonic bonding, it is preferable to select a 6000 series aluminum alloy (for example, A6063) with good surface finish due to the addition of Mg and Si for the main body 34 and the first frame 81.

[0062] The joining of the protruding portion 89 of the first frame 81 and the first seating surface 41 of the main body 34 may be performed by resistance welding instead of ultrasonic welding. In resistance welding, the first frame 81 and the main body 34 are joined by passing an electric current through them to generate heat, causing them to melt together. When resistance welding is performed, an anodic oxide film may be formed on the joining surfaces of the aluminum protruding portion 89 and the first seating surface 41 in order to ensure the electrical resistance of the first frame 81 and the main body 34 through which the electric current is passed. Even with resistance welding, the first frame 81 and the main body 34 become one unit, and a seal is ensured between the first frame 81 and the main body 34.

[0063] According to the second embodiment described above, the first to third frames 81 to 83 are joined to the first to third infrared-transmitting windows 21 to 23 at room temperature. Although this requires the formation of metal layers 86 and 88 and underlay layers 85 and 87, the process time per room-temperature joining can be shortened through mass production, improving workability compared to bonding with organic adhesives.

[0064] Furthermore, by performing joining by room temperature joining, ultrasonic joining, or resistance welding, as in the second embodiment, the release of degassing gas and the adsorption of sealed gas can be eliminated, similar to the first embodiment, and the sensitivity of the sensor unit 60 can be maintained well over a long period of time. Note that the above-mentioned resistance welding is a welding method that uses electrical energy, and it may be changed to other welding methods that use electrical energy, such as TIG welding, plasma welding, or electron beam welding, as long as it is possible to join in the same manner as in this embodiment.

[0065] Furthermore, the present invention is not limited to the embodiments described above, and can be implemented with various modifications. In the embodiments described above, the size, shape, orientation, etc., shown in the accompanying drawings are not limited thereto, and can be appropriately modified within the scope that allows the present invention to exert its effects. In addition, the present invention can be implemented with appropriate modifications as long as it does not deviate from the scope of its objectives.

[0066] In the first embodiment described above, low-melting-point glass was used for joining by each joining member 45-48, but solder members may be used instead. When solder members are used, a metal layer is formed in each joining region in the same manner as the metal layers 86 and 88 described above, and the joining is performed on these metal layers via the joining members 45-48, which are solder members. Even with a configuration in which solder members are used for each joining member 45-48, the same operation and effect as in the first embodiment can be obtained. In this configuration, when joining the front gas chamber forming body 27 and the rear gas chamber forming body 28, a solder member is used instead of the low-melting-point glass 58, and the melting point of the solder member is set lower than the melting point of the solder member used for each joining member 45-48. When joining the front gas chamber forming body 27 and the rear gas chamber forming body 28 with a solder member, the same metal layer as described above is formed in each joining region.

[0067] Furthermore, the joining by the joining members 45 to 48 in the first embodiment may be changed to room-temperature joining via the metal layers 86 and 88 in the second embodiment.

[0068] Furthermore, the joining by each joining member 45 to 48 in the first embodiment may be modified to form metal layers 86 and 88, similar to the second embodiment, and ultrasonic bonding may be performed via the metal layers 86 and 88, as described above.

[0069] Furthermore, the joining of the first to third infrared-transmitting windows 21 to 23 and the first to third frames 81 to 83 in the second embodiment may also be changed from room-temperature joining to ultrasonic joining.

[0070] Furthermore, in the second embodiment, the joining of the first to third infrared-transmitting windows 21 to 23 and the first to third frames 81 to 83 may be changed to joining via joining members 45 to 48 (low-melting point glass, solder member), which are the same as in the first embodiment.

[0071] Furthermore, in the first embodiment, the joining of the frame bodies 35a to 35c, 52 to the main body 34, and in the second embodiment, the joining of the first to third frame bodies 81 to 83 to the main body 34, may be performed by forming a metal layer in each of the joining regions in the same manner as the metal layers 86 and 88 described above, and bonding at room temperature via the metal layer.

[0072] Furthermore, in each gas chamber forming body 27, 28, the infrared-transmitting windows 21-24 are joined by interposing each frame 35a-35c, 52, 81-83. However, the joining may be performed without each frame 35a-35c, 52, 81-83, as long as the joining can be done in the same manner as in the above embodiment.

[0073] Furthermore, in the infrared gas analyzer 1, the connection between the light source chamber 3 and the window plate 5, and the connection between the cell body 10 and the window plates 13 and 14 in the sample cell 9, may also be made as in the embodiments described above. [Explanation of symbols]

[0074] 1: Infrared gas analyzer 20: Detector for infrared gas analyzer 21: First infrared-transmitting window (infrared-transmitting window) 22: Second infrared-transmitting window (infrared-transmitting window) 23: Third infrared-transmitting window (infrared-transmitting window) 24: Fourth infrared-transmitting window (infrared-transmitting window) 27: Front gas chamber former (gas chamber former) 28: Rear gas chamber former (gas chamber former) 31: First Gas Chamber (Gas Chamber) 32: Second Gas Chamber (Gas Chamber) 34: Main body 35a: Frame 35b:Frame body 35c:Frame body 45: Joining member 46: Joining member 47: Joining member 48: Joining member 49: Third Gas Chamber (Gas Chamber) 51: Main body 52: Frame 58: Low melting point glass 60: Sensor section 62: Containment space 80: Detector for infrared gas analyzer 81: First frame (frame) 82: Second frame (frame) 83: Third frame (frame) 86: Metal layer 88: Metal layer

Claims

1. A detector for an infrared gas analyzer capable of detecting the concentration of a target gas, An infrared-transmitting window that allows infrared rays to pass through, Multiple gas chamber forming bodies, which are joined together to form gas chambers in which the gas component to be measured is sealed, The device comprises a sensor unit housed in a containment space communicating with the gas chambers formed in each of the multiple gas chamber forming bodies, and which detects the concentration of the target gas by detecting the gas flow generated in the containment space, The gas chamber forming body comprises a frame to which the infrared-transmitting window is joined, and a main body that forms the gas chamber and to which the frame is joined. The frame and the main body are joined together by welding using light energy. The infrared-transmitting window is joined to the frame via a joining member, and the joining member is made of low-melting-point glass. A detector for an infrared gas analyzer, characterized in that the gas chamber forming bodies are joined together by low-melting-point glass with a lower melting point than the low-melting-point glass used in the joining member.

2. A detector for an infrared gas analyzer capable of detecting the concentration of a target gas, An infrared-transmitting window that allows infrared rays to pass through, Multiple gas chamber forming bodies, which are joined together to form gas chambers in which the gas component to be measured is sealed, The device comprises a sensor unit housed in a containment space communicating with the gas chambers formed in each of the multiple gas chamber forming bodies, and which detects the concentration of the target gas by detecting the gas flow generated in the containment space, The gas chamber forming body comprises a frame to which the infrared-transmitting window is joined, and a main body that forms the gas chamber and to which the frame is joined. The frame and the main body are joined together by welding using light energy. A metal layer formed in the joint region between the infrared-transmitting window and the frame is joined to the frame via a soldering member, A detector for an infrared gas analyzer, characterized in that the gas chamber forming bodies are joined together by a soldering material having a lower melting point than the soldering material used for the joining member.

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