Constant potential electrolytic gas sensor and method for manufacturing a constant potential electrolytic gas sensor

Abstract

A constant potential electrolysis gas sensor 1 according to the present invention is characterized by comprising: a case provided with a case body 21; an electrode structure 3 including electrodes 31, 32, 33 provided to the case body 21; lead wires 41, 42, 43 connected to surfaces of the electrodes 31, 32, 33; and external electrodes 51, 52, 53 which extend from the outside of the case to the inside of the case, which are provided to the case body 21, and to which the lead wires 41, 42, 43 are connected. The constant potential electrolysis gas sensor is also characterized in that: the external electrodes 51, 52, 53 are disposed such that connection parts CP, of the external electrodes 51, 52, 53 to which the lead wires 41, 42, 43 are connected, are located at a height corresponding to the electrode structure 3; and the case body 21 has holding structures 8 capable of holding a predetermined amount of a protective agent so as to cover the connection parts CP, with respect to the external electrodes 51, 52, 53.

Description

Technical Field

[0005] ,

[0001] The present invention relates to a potentiostatic electrolytic gas sensor and a method for manufacturing the potentiostatic electrolytic gas sensor.

Background Art

[0002] As a sensor for detecting a gas to be detected, for example, a potentiostatic electrolytic gas sensor as disclosed in Patent Document 1 is used. The potentiostatic electrolytic gas sensor of Patent Document 1 includes a sensor case, a working electrode, a counter electrode, and a reference electrode provided on an electrode holder in the sensor case, three connection terminals provided on the lower wall of the sensor case below the electrode holder, and lead wires connecting each electrode and each connection terminal. In this potentiostatic electrolytic gas sensor, the potential of the working electrode with respect to the reference electrode is controlled to be constant, and the electrolytic current generated between the working electrode and the counter electrode due to the electrochemical reaction of the gas to be detected is detected, whereby the gas to be detected can be detected.

[0003] In the potentiostatic electrolytic gas sensor of Patent Document 1, the electrode holder is inserted into the sensor case such that the terminal to which the lead wire is connected is press-fitted into the lower wall of the sensor case, and the lead wire extends over the electrode holder through the side surface of the electrode holder. After each electrode is provided on the electrode holder, the lead wire is bent along the surface of each electrode and connected to the surface of each electrode to be manufactured.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

[0005] In constant potential electrolytic gas sensors, if the connection point where the lead wires connect to the terminals is immersed in the electrolyte, corrosion may occur at the connection point, potentially causing errors in the measured electrolytic current. Therefore, a protective agent must be applied to the connection point where the lead wires connect to the terminals to protect them from corrosion by the electrolyte. However, the constant potential electrolytic gas sensor described in Patent Document 1 does not have a structure to hold a predetermined amount of protective agent near the connection point between the lead wires and terminals, making it difficult to control the amount of protective agent applied while keeping the amount to a minimum. Furthermore, because the connection point is located below the electrode holder, the protective agent must be applied before installing the electrode holder, and then the lead wires must be bent and positioned on the surface of each electrode after the electrode holder and each electrode have been installed. Thus, the application of the protective agent and the routing of the lead wires are extremely difficult and complicated, making it difficult to manufacture the sensor easily, which hinders the automation of the manufacturing process.

[0006] The present invention has been made in view of the above problems, and aims to provide a constant potential electrolytic gas sensor and a method for manufacturing a constant potential electrolytic gas sensor that can be easily manufactured, with easy application of a predetermined amount of protective agent and routing of lead wires.

[0007] The present invention provides a constant potential electrolytic gas sensor comprising: a case having a case body; an electrode structure including at least two electrodes provided on the case body; at least two lead wires extending along the respective surfaces of the at least two electrodes and connected to the respective surfaces of the at least two electrodes; and at least two external electrodes extending from outside the case into the case and provided on the case body and connected to each of the at least two lead wires, wherein the at least two external electrodes are arranged such that the connection points of the external electrodes to which the lead wires are connected are located at a height corresponding to the electrode structure, and the case body has a holding structure for each of the at least two external electrodes that can hold a predetermined amount of protective agent so as to cover the connection points.

[0008] The present invention relates to a method for manufacturing a constant potential electrolytic gas sensor, wherein the constant potential electrolytic gas sensor comprises a case having a case body, an electrode structure including at least two electrodes provided on the case body, at least two lead wires extending along the respective surfaces of the at least two electrodes and connected to the respective surfaces of the at least two electrodes, and at least two external electrodes extending from outside the case into the case and provided on the case body and connected to each of the at least two lead wires, wherein the at least two external electrodes are arranged such that the connection points of the external electrodes to which the lead wires are connected are located at a height corresponding to the electrode structure, and the case body has a holding structure portion for each of the at least two external electrodes that can hold a predetermined amount of protective agent so as to cover the connection points, and the method is characterized by comprising the steps of: arranging the lead wires between the surface of the electrode and the connection points of the external electrodes; connecting the lead wires to the external electrodes at the connection points of the external electrodes while the lead wires are arranged on the surface of the electrode; and supplying the predetermined amount of protective agent to the holding structure portion so as to cover the connection points of the external electrodes with the protective agent. [Brief explanation of the drawing]

[0009] [Figure 1] This is an exploded perspective view of a constant potential electrolytic gas sensor according to the first embodiment of the present invention. [Figure 2] Figure 1 is a cross-sectional view of a constant potential electrolytic gas sensor. [Figure 3] Figure 1 is a perspective view of the case body of the constant potential electrolytic gas sensor. [Figure 4] Figure 1 is a top view of the case body of the constant potential electrolytic gas sensor. [Figure 5] Figure 4 is a cross-sectional view along the VV line. [Figure 6] This is a cross-sectional view of the modified case body corresponding to Figure 5. [Figure 7] This is a cross-sectional view of the case body of another modified example, corresponding to Figure 5. [Figure 8]Figure 5 shows the case body with the counter electrode placed inside and the lead wire for the counter electrode installed. [Figure 9] This figure shows the state after the condition shown in Figure 8, with a lead wire for the counter electrode placed between the surface of the counter electrode and the connection point for the external electrode for the counter electrode, and the lead wire for the counter electrode connected to the external electrode for the counter electrode. [Figure 10] This figure shows the state after the conditions shown in Figure 9, with the reference electrode and its lead wires positioned. [Figure 11] This figure shows the state after the condition shown in Figure 10, with the reaction electrode lead wires introduced, connected to the reaction electrode external electrode, and the holding structure filled with protective agent. [Figure 12] This figure shows the state after the reaction electrode has been placed, following the state shown in Figure 11. [Figure 13] This is an exploded perspective view of a constant potential electrolytic gas sensor according to a second embodiment of the present invention. [Figure 14] Figure 13 is a top view of the case body of the constant potential electrolytic gas sensor. [Figure 15] This is an exploded perspective view of a constant potential electrolytic gas sensor according to a third embodiment of the present invention. [Figure 16] Figure 15 is a top view of the case body of the constant potential electrolytic gas sensor. [Modes for carrying out the invention]

[0010] Hereinafter, with reference to the attached drawings, several embodiments of the constant potential electrolytic gas sensor of the present invention will be described. However, the embodiments shown below are examples only, and the constant potential electrolytic gas sensor of the present invention is not limited to the following examples.

[0011] In this specification, the term "height direction H" is used, and "height direction H" means the direction perpendicular to the surface of the reaction electrode 31 or counter electrode 32 included in the electrode structure 3, as shown in Figures 1 to 3, for example. Furthermore, one side in the height direction H (in the illustrated example, the side opposite to the external electrodes 51, 52, and 53 with respect to the connection point CP of the external electrodes 51, 52, and 53 to which the lead wires 41, 42, and 43 are connected, the upper side in the figure) is defined as the upper side, and the other side in the height direction H (in the illustrated example, the side of the external electrodes 51, 52, and 53 with respect to the connection point CP of the external electrodes 51, 52, and 53 to which the lead wires 41, 42, and 43 are connected, the lower side in the figure) is defined as the lower side. Furthermore, the direction perpendicular to the height direction H is defined as the horizontal direction.

[0012] <First Embodiment> The constant potential electrolytic gas sensor 1 of the first embodiment (hereinafter referred to as "gas sensor 1") comprises a case 2, an electrode structure 3 housed within the case 2, lead wires 4 connected to the electrode structure 3, and an external electrode 5 connected to the lead wires 4, as shown in Figures 1 and 2. The gas sensor 1 further comprises an electrolyte 6 provided in contact with the electrode structure 3. The gas sensor 1 is connected via the external electrode 5 to a control device (not shown), such as a potentiostat. The gas sensor 1 detects the target gas in the ambient gas by having the control device apply a constant potential to the electrode structure 3 and detecting the electrical signal produced as a result of the electrochemical reaction occurring in the electrode structure 3.

[0013] The detection target gas to be detected by the gas sensor 1 is not particularly limited, and examples include oxygen gas, hydrogen sulfide gas, ammonia gas, nitrogen dioxide gas, nitrogen trifluoride gas, chlorine gas, fluorine gas, iodine gas, chlorine trifluoride gas, ozone gas, hydrogen peroxide gas, hydrogen fluoride gas, hydrogen chloride gas (hydrochloric acid gas), carbon monoxide gas, hydrogen gas, sulfur dioxide gas, silane gas, disilane gas, phosphine gas, germanium gas, etc. Note that the detection target gas of the gas sensor 1 in this embodiment is oxygen gas. Hereinafter, an example in which the gas sensor 1 is configured as an oxygen gas sensor will be described. However, the gas sensor of the present invention can be configured to be changed according to the detection target gas.

[0014] Case 2 is a member that houses the electrode structure 3, the lead wire 4, the external electrode 5 extending into the case 2, and the electrolytic solution 6. As shown in FIGS. 1 and 2, the case 2 includes a case body 21 and a case cover 22. When the case body 21 is closed by the case cover 22, an internal space S for housing the above members is formed inside the case 2. In particular, in this embodiment, when the case body 21 is closed by the case cover 22, an electrolytic solution housing space CS for housing the electrolytic solution 6 is formed inside the case 2. The internal space S is hermetically sealed by air-permeable sheets 31b, OS, buffer films IB, and OB described later so that gas can flow in and out. The case body 21 and the case cover 22 are fixed to each other by known bonding means such as ultrasonic welding or an adhesive. The case body 21 and the case cover 22 are not particularly limited, and can be formed by known resin molding or cutting techniques using, for example, known resin materials and various resin-like materials.

[0015] The case body 21 is a member that supports the electrode structure 3, the lead wire 4, the external electrode 5, and the electrolytic solution 6. The case body 21 only needs to be able to support the above members, and its structure is not particularly limited. In the present embodiment, as shown in FIGS. 2 to 4, the case body 21 includes a base portion 211, an electrode structure support portion 212, an intermediate support portion 213, and a plurality of external electrode support portions 214. The case body 21 is formed such that the base portion 211, the electrode structure support portion 212, the intermediate support portion 213, and the external electrode support portion 214 are integrated. In particular, in the present embodiment, the case body 21 is formed integrally with the external electrode 5 by insert molding. Thereby, the process for attaching the external electrode 5 to the case body 21 can be omitted. However, the case body 21 may be fixed to each other after each part is formed separately.

[0016] The base portion 211 is a portion that supports the electrode structure support portion 212, the intermediate support portion 213, and the external electrode support portion 214. The base portion 211 further supports the electrolytic solution 6 accommodated in the electrolytic solution accommodation space CS formed by closing the case body 21 with the case cover 22. As shown in FIGS. 2 to 4, the base portion 211 is formed in a flat plate shape (substantially circular plate shape in the illustrated example), the intermediate support portion 213 is fixed to substantially the center of the flat plate surface (upper surface), and a plurality of external electrode support portions 214 are fixed at substantially equal intervals along the periphery of the flat plate surface. A gas outflow hole h2 that is continuously provided through the electrode structure support portion 212 and the intermediate support portion 213 is formed in the base portion 211. The gas flows out from the internal space S formed inside the case 2 through the gas outflow hole h2 that is continuously formed in the electrode structure support portion 212, the intermediate support portion 213, and the base portion 211.

[0017] The electrode structure support portion 212 is the part that supports the electrode structure 3 and the lead wires 4 connected to the electrode structure 3. The electrode structure support portion 212 is supported by an intermediate support portion 213 and an external electrode support portion 214 relative to the base portion 211. As shown in Figures 2 to 4, the electrode structure support portion 212 is formed in a flat plate shape, with the intermediate support portion 213 fixed approximately at the center of the bottom surface (lower surface) of the flat plate, and a plurality of external electrode support portions 214 fixed along the periphery of the flat plate at approximately equal intervals from each other. Above approximately the center of the flat plate surface of the electrode structure support portion 212, an electrode structure support space SS (see Figures 1 and 3) for supporting the electrode structure 3 is formed, surrounded by the plurality of external electrode support portions 214. A recess 212r is formed on the surface of the electrode structure support portion 212 below the electrode structure support space SS, and a gas outlet hole h2 is formed below the recess 212r, which is provided in a manner with respect to the intermediate support portion 213 and the base portion 211.

[0018] The outflow-side buffer membrane OB, provided in the recess 212r of the electrode structure support portion 212, works together with the outflow-side permeable sheet OS to suppress the outflow of electrolyte 6 through the gas outflow hole h2 and to regulate the pressure inside the case 2. As shown in Figure 2, the outflow-side buffer membrane OB is held within the recess 212r by the outflow-side permeable sheet OS closing the opening of the recess 212r of the electrode structure support portion 212. As the outflow-side buffer membrane OB, a membrane that suppresses the passage of liquid and allows the passage of gas can be used, for example, a porous membrane made of a fluororesin such as polytetrafluoroethylene (PTFE) can be used.

[0019] The outflow-side permeable sheet OS, together with the outflow-side buffer membrane OB, liquid-tightly seals the gas outflow hole h2 of the electrode structure support portion 212. As shown in Figure 1, the outflow-side permeable sheet OS comprises a sheet-like main body portion OS1 (in the illustrated example, a roughly circular sheet) and a plurality of sheet-like extension portions OS2 (four in the illustrated example) (in the illustrated example, roughly rectangular sheets) that protrude out of plane from the main body portion OS1 and are arranged at roughly equal intervals from each other in the circumferential direction of the main body portion OS1. The main body portion OS1 is positioned in the electrode structure support space SS above the electrode structure support portion 212. The extension portions OS2 extend along the surface of the electrode structure support portion 212, through the gaps between adjacent external electrode support portions 214, 214, and are arranged to be bent at the outer edge of the electrode structure support portion 212 and extend into the electrolyte containment space CS, as shown in Figure 2. The outflow-side permeable sheet OS is fixed to the surface of the electrode structure support 212 by heat-sealing it in a ring shape to the surface of the electrode structure support 212, which is located outside the outer circumference of the recess 212r of the electrode structure support 212, thereby closing the recess 212r of the electrode structure support 212. As the outflow-side permeable sheet OS, a sheet that suppresses the passage of liquids and allows the passage of gases can be used, for example, a porous sheet made of a fluororesin such as polytetrafluoroethylene (PTFE) can be used.

[0020] The intermediate support portion 213 is the part that supports the electrode structure support portion 212 relative to the base portion 211. As shown in Figure 2, the intermediate support portion 213 is formed in a columnar shape so as to extend in the height direction H from approximately the center of the flat plate surface of the base portion 211, and is fixed to the base portion 211 at its lower end in the height direction H and fixed to the electrode structure support portion 212 at its upper end in the height direction H. A gas outlet hole h2 is formed in the intermediate support portion 213, which extends continuously from the electrode structure support portion 212 through the intermediate support portion 213 and through the base portion 211.

[0021] The external electrode support portion 214 is the part that supports the external electrode 5 and the lead wire 4 connected to the external electrode 5. The external electrode support portion 214 further supports the electrode structure support portion 212 relative to the base portion 211. As shown in Figure 3, the external electrode support portion 214 is formed in a columnar shape extending along the height direction H from near the periphery of the flat surface of the base portion 211, fixed to the base portion 211 at its lower end in the height direction H, and fixed to the electrode structure support portion 212 at an intermediate position in the height direction H. The external electrode 5 is fixed to the external electrode support portion 214, extending along the height direction H of the external electrode support portion 214 and penetrating the external electrode support portion 214. Multiple external electrode support portions 214 are provided (three in the illustrated example) depending on the number of external electrodes 5 required, and the multiple external electrode support portions 214 are arranged at approximately equal intervals from each other along the periphery of the flat surface of the base portion 211. In the illustrated example, there is one support portion that is substantially the same shape as the external electrode support portion 214 but does not support the external electrode 5. Including this support portion, four support portions are arranged at substantially equal intervals from one another along the periphery of the flat plate surface of the base portion 211.

[0022] As shown in Figure 3, the external electrode support portion 214 comprises a lower external electrode support portion 214a located below the electrode structure support portion 212 in the height direction H, and an upper external electrode support portion 214b located above the electrode structure support portion 212 in the height direction H. The lower external electrode support portion 214a supports the external electrode 5 and also supports the electrode structure support portion 212. The upper external electrode support portion 214b supports the external electrode 5 and positions the connection point CP of the external electrode 5 with the lead wire 4 (for example, the upper end of the external electrode 5) at a height corresponding to the electrode structure 3. In relation to the fact that the connection point CP of the external electrode 5 is provided on the upper external electrode support portion 214b, the upper external electrode support portion 214b may include a guide portion 7 for guiding the lead wire 4 and a holding structure portion 8 capable of holding a protective agent for protecting the connection point CP of the external electrode 5. Details of the guide portion 7 and the holding structure portion 8 will be described in detail below.

[0023] As shown in Figures 3 and 4, the upper external electrode support portion 214b is formed in a substantially fan shape, with its radially inner portion cut out in a substantially concentric manner when viewed in the height direction H. As a result, on the surface of the electrode structure support portion 212 located horizontally inward from the upper external electrode support portion 214b, an electrode structure support space SS is formed in a substantially cylindrical shape, surrounded by multiple upper external electrode support portions 214b, in which the electrode structure 3 is supported. The upper external electrode support portions 214b surrounding the electrode structure support space SS restrict the electrode structure 3, supported within the electrode structure support space SS, from deviating horizontally outward from the electrode structure support space SS. The multiple upper external electrode support portions 214b are arranged at substantially equal intervals from each other along the periphery of the electrode structure support space SS. Between adjacent upper external electrode support portions 214b, 214b, a gap is formed extending from the approximate center to the periphery of the flat surface of the electrode structure support portion 212. This gap is formed to a size corresponding to the extension portion OS2 of the outflow-side permeable sheet OS (see Figure 1) and the extension portion 37b of the electrolyte supply electrolyte holding member 37 included in the electrode structure 3 (see Figure 1). By positioning the respective extension portions OS2 and 37b of the outflow-side permeable sheet OS and the electrolyte supply electrolyte holding member 37 within this gap, rotational movement around the axis extending in the height direction H is restricted.

[0024] The case cover 22 is a member that closes the case body 21 so as to form an internal space S within the case 2. In this embodiment, the case cover 22 is formed in a cylindrical shape with one end (upper end) closed, as shown in Figures 1 and 2. The case cover 22 is fixed to the base 211 of the case body 21 so as to cover and conceal the electrode structure support portion 212, the intermediate support portion 213, and the external electrode support portion 214 of the case body 21 inside the cylinder. When the case body 21 is closed by the case cover 22, the internal space S is formed, and at the same time, an electrolyte storage space CS is formed between the inner surface of the case cover 22 and the base 211 and electrode structure support portion 212 of the case body 21.

[0025] As shown in Figures 1 and 2, a capillary member 22c with a gas inlet hole h1 is fixed to the wall (upper wall) at one end of the case cover 22 using an adhesive or an elastic material (such as a packing or thermoplastic elastomer). The gas outside the case 2, including the target gas to be detected, flows into the reaction electrode 31 inside the case 2 through the gas inlet hole h1. Here, the gas inlet hole h1 needs to be configured to limit the amount of target gas flowing into the case 2 to a predetermined amount or less in order to keep the signal intensity low when the electrode structure 3 detects the target gas. For this purpose, the diameter of the gas inlet hole h1 needs to be as small as possible (for example, 50 μmφ). In this embodiment, when the case cover 22 is formed in a cylindrical shape with one end closed by, for example, resin molding, it is difficult to provide such a fine gas inlet hole in the wall at one end of the case cover 22 at the same time as resin molding. By fixing a capillary member 22c, which has fine gas inlet holes h1 pre-drilled into it, to a molded case cover 22, the case cover 22 can be easily provided with fine gas inlet holes h1.

[0026] On the inner side of the upper wall of the case cover 22, a recess 22r is formed where the inlet-side buffer membrane IB is provided, as shown in Figure 2. The inlet-side buffer membrane IB provided in the recess 22r, together with the permeable sheet 31b described later, has the function of suppressing the outflow of electrolyte 6 through the gas inlet hole h1 and adjusting the pressure inside the case 2. The inlet-side buffer membrane IB is fixed in the recess 22r of the case cover 2 by known fixing means such as donut-shaped double-sided tape. As the inlet-side buffer membrane IB, a membrane that suppresses the passage of liquid and allows the passage of gas can be used, for example, a porous membrane made of a fluororesin such as polytetrafluoroethylene (PTFE) can be used.

[0027] The electrode structure 3 detects the target gas by generating an electrochemical reaction related to the target gas in the electrolyte 6. The electrode structure 3 is provided on the case body 21, but its arrangement is not particularly limited. In this embodiment, as shown in Figures 1 to 4, the electrode structure 3 is arranged in the electrode structure support space SS formed on the electrode structure support portion 212, and is supported within the case 2 by being sandwiched between the electrode structure support portion 212 and the upper wall of the case cover 22. The electrode structure 3 is formed to a size corresponding to the electrode structure support space SS, and the horizontal outward deviation of the electrode structure support space SS is restricted by a plurality of external electrode support portions 214 arranged around the electrode structure support space SS. Note that in Figures 3 and 4, other components included in the electrode structure 3 are omitted from the illustration in order to make the arrangement of electrodes 31, 32, and 33 within the electrode structure 3 easier to see.

[0028] In this embodiment, the electrode structure 3, as shown in Figures 1 and 2, comprises a reaction electrode 31 that generates an electrochemical reaction related to the gas to be detected, a counter electrode 32 that generates another electrochemical reaction corresponding to the electrochemical reaction related to the gas to be detected, and a reference electrode 33 that serves as a reference for the potential of the reaction electrode 31. The reaction electrode 31, counter electrode 32, and reference electrode 33 are arranged to be in contact with the electrolyte 6 and are electrically connected to the external electrode 5 via lead wires 4. The electrode structure 3 only needs to be configured to detect the gas to be detected through an electrochemical reaction related to the gas to be detected, and for that purpose, it is sufficient to have at least two electrodes, namely the reaction electrode 31 and the counter electrode 32.

[0029] The reaction electrode 31 only needs to be able to produce an electrochemical reaction related to the gas to be detected in the electrolyte 6, and its configuration and arrangement are not particularly limited. In this embodiment, as shown in Figures 1 and 2, the reaction electrode 31 comprises a film-like catalyst layer 31a (in the illustrated example, a film-like shape approximately circular in shape) having a surface approximately perpendicular to the height direction H, and a breathable sheet 31b supporting the catalyst layer 31a. The reaction electrode 31 is fixed to the case cover 22 via the breathable sheet 31b. The reaction electrode 31 is incorporated into the electrode structure 3 when the case body 21 is closed by the case cover 22. Below the reaction electrode 31 in the height direction H, a reference electrode 33 and a counter electrode 32 are stacked in order, spaced apart from the reaction electrode 31. Reaction electrode lead wires 41, which will be described later, are connected to the surface of the catalyst layer 31a of the reaction electrode 31. The reaction electrode 31 is formed by depositing a catalyst layer 31a on a breathable sheet 31b using a known electrode material such as platinum, by known film formation techniques such as coating, vapor deposition, or sputtering. The catalyst layer 31a of the reaction electrode 31 is formed to have substantially the same shape and surface area (area of ​​the surface facing the height direction H) as the counter electrode 32 and the reference electrode 33.

[0030] The permeable sheet 31b of the reaction electrode 31, together with the inlet-side buffer membrane IB, liquid-tightly seals the gas inlet hole h1. As shown in Figure 2, the permeable sheet 31b is fixed to the case cover 22 by heat-sealing it to a ring-shaped projection 22p provided on the outer circumference of the recess 22r of the case cover 22, thereby closing the recess 22r. The permeable sheet 31b is configured as a sheet that suppresses the passage of liquids and allows the passage of gases, and is configured as, for example, a porous sheet made of a fluororesin such as polytetrafluoroethylene (PTFE).

[0031] The counter electrode 32 only needs to be able to generate another electrochemical reaction corresponding to the electrochemical reaction related to the gas to be detected, and its configuration and arrangement are not particularly limited. In this embodiment, as shown in Figures 1 and 2, the counter electrode 32 is formed in the form of a film (in the illustrated example, a roughly circular film) having a surface substantially perpendicular to the height direction H, and is placed on the main body OS1 of the outlet side permeable sheet OS. Above the counter electrode 32 in the height direction H, the reference electrode 33 and the reaction electrode 31 are stacked in order along the height direction H, spaced apart from the counter electrode 32. However, the counter electrode 32 may be placed next to the reaction electrode 31 or the reference electrode 33 at a position where it is at substantially the same height in the height direction H. A counter electrode lead wire 42, which will be described later, is connected to the surface of the counter electrode 32. The counter electrode 32 is supported on the outlet side permeable sheet OS by being pressed by the case cover 22 via components on the counter electrode 32. The counter electrode 32 can be formed, for example, by depositing a known electrode material such as platinum onto a breathable sheet (not shown) of the same type as the breathable sheet 31b, similar to the reaction electrode 31, using a known film deposition technique.

[0032] The reference electrode 33 only needs to be able to serve as a reference for the potential of the reaction electrode 31, and its configuration and arrangement are not particularly limited. In this embodiment, the reference electrode 33 is formed in the form of a film (in the illustrated example, a film that is approximately circular) having a surface that is approximately perpendicular to the height direction H, and is stacked along the height direction H between the reaction electrode 31 and the counter electrode 32, with a gap between them. However, the reference electrode 33 may be arranged side by side with the reaction electrode 31 or the counter electrode 32 at a position that is approximately the same height in the height direction H. A lead wire 43 for the reference electrode, which will be described later, is connected to the surface of the reference electrode 33. The reference electrode 33 is supported between the reaction electrode 31 and the counter electrode 32 by being sandwiched between the upper and lower components of the reference electrode 33 in the height direction H. The reference electrode 33 can be formed, for example, by depositing a known electrode material such as platinum on the same type of breathable sheet (not shown) as the breathable sheet 31b using a known film deposition technique, similar to the reaction electrode 31.

[0033] In the gas sensor 1 of this embodiment, a control device (not shown), such as a potentiostat connected to the external electrode 5, applies a constant voltage to the reaction electrode 31 based on the potential of the reference electrode 33, thereby creating a constant potential difference between the reaction electrode 31 and the reference electrode 33. When the target gas flows onto the reaction electrode 31, the reaction electrode 31, with a constant potential difference between it and the reference electrode 33, generates an electrochemical reaction related to the target gas. When an electrochemical reaction related to the target gas occurs, another electrochemical reaction occurs on the counter electrode 32 side in response to that electrochemical reaction. As a result of the electrochemical reactions occurring in the reaction electrode 31 and the counter electrode 32, an electrolytic voltage is generated between the reaction electrode 31 and the counter electrode 32, causing an electrolytic current to flow. By detecting this electrolytic current, the target gas can be detected, and the concentration of the target gas can be determined according to the magnitude of the electrolytic current.

[0034] The reaction electrode 31, counter electrode 32, and reference electrode 33 of the electrode structure 3 only need to be arranged to be in contact with the electrolyte 6, and the method of contact with the electrolyte 6 is not particularly limited. In this embodiment, the electrode structure 3 includes electrolyte holding members 34, 35, 36, and 37 capable of holding the electrolyte 6, as shown in Figures 1 and 2. The reaction electrode 31, counter electrode 32, and reference electrode 33 are arranged to be in contact with the electrolyte 6 held by the electrolyte holding members 34, 35, 36, and 37 via the electrolyte holding members 34, 35, 36, and 37. However, the reaction electrode 31, counter electrode 32, and reference electrode 33 may be arranged to be in direct contact with the electrolyte 6.

[0035] The electrolyte holding members 34, 35, 36, and 37 are configured to hold the electrolyte 6 and to bring the held electrolyte 6 into contact with the reaction electrode 31, the counter electrode 32, and the reference electrode 33. In this embodiment, the electrolyte holding members include an electrolyte holding member 34 for the reaction electrode, an electrolyte holding member 35 for the counter electrode, an electrolyte holding member 36 for the reference electrode, and an electrolyte supply electrolyte holding member 37, as shown in Figures 1 and 2. Each of the electrolyte holding members 34, 35, 36, and 37 is arranged to be in contact with each other and to indirectly connect the reaction electrode 31, the counter electrode 32, and the reference electrode 33 to each other via the held electrolyte 6. The main body portion 37a of the electrolyte holding member 34 for the reaction electrode, the electrolyte holding member 35 for the counter electrode, the electrolyte holding member 36 for the reference electrode, and the electrolyte supply electrolyte holding member 37, which will be described later, is formed to be substantially the same shape and size as the other, and has the largest surface area (area of ​​the surface facing the height direction H) among the components of the electrode structure 3, defining the outer edge of the electrode structure 3. In Figure 2, in order to make the layered structure of the electrode structure 3 easier to understand, the electrolyte holding members 34, 35, 36, and 37 (especially the electrolyte holding members 34, 36, and 37) are shown to be spaced apart from each other, but in reality, the ring-shaped portions of the electrolyte holding members 34, 35, 36, and 37 that extend out of the plane of the respective electrodes 31, 32, and 33 are in contact with each other.

[0036] As shown in Figures 1 and 2, the electrolyte holding member 34 for the reaction electrode contacts the reaction electrode 31 and brings the electrolyte 6 it holds into contact with the reaction electrode 31. The electrolyte holding member 34 for the reaction electrode is formed in a sheet shape (in the illustrated example, a roughly circular sheet shape) and is positioned between the reaction electrode 31 and the reference electrode 33 in the height direction H so as to be in surface contact with the surface of the reaction electrode 31. The electrolyte holding member 34 for the reaction electrode has a larger surface area (area of ​​the surface facing the height direction H) than each of the electrodes 31, 32, and 33. The portion of the electrolyte holding member 34 for the reaction electrode that extends in a ring shape outside the plane of each of the electrodes 31, 32, and 33 is positioned so as to be in contact with the electrolyte holding member 36 for the reference electrode. By contacting the electrolyte holding member 34 for the reaction electrode, the electrolyte 6 is supplied from the electrolyte holding member 36 for the reference electrode. In the illustrated example, the electrolyte holding member 34 for the reaction electrode is a roughly circular sheet, but like the electrolyte holding member 37 for supplying electrolyte, which will be described later, it may also comprise a sheet-shaped main body (for example, a roughly circular sheet) and a plurality (for example, four) sheet-shaped extensions (for example, a roughly rectangular sheet) that protrude out of the plane from the main body and are arranged at roughly equal intervals from each other in the circumferential direction of the main body.

[0037] As shown in Figures 1 and 2, the counter electrode electrolyte holding member 35 contacts the counter electrode 32 and brings the electrolyte 6 it holds into contact with the counter electrode 32. Also, as shown in Figures 1 and 2, the counter electrode electrolyte holding member 35 is positioned between the counter electrode 32 and the electrolyte supply electrolyte holding member 37 in the height direction H, so as to be in surface contact with the surfaces of the counter electrode 32 and the main body portion 37a of the electrolyte supply electrolyte holding member 37. The counter electrode electrolyte holding member 35 has a larger surface area (area of ​​the surface facing the height direction H) than each electrode 31, 32, and 33. By contacting the main body portion 37a of the electrolyte supply electrolyte holding member 37, the electrolyte 6 is supplied from the electrolyte supply electrolyte holding member 37 to the counter electrode electrolyte holding member 35. In the illustrated example, the counter electrode electrolyte holding member 35 is a roughly circular sheet, but like the electrolyte supply electrolyte holding member 37 described later, it may also comprise a sheet-shaped main body (for example, a roughly circular sheet) and a plurality (for example, four) sheet-shaped extensions (for example, a roughly rectangular sheet) that protrude out of the plane from the main body and are arranged at roughly equal intervals from each other in the circumferential direction of the main body.

[0038] As shown in Figures 1 and 2, the reference electrode electrolyte holding member 36 contacts the reference electrode 33 and brings the electrolyte 6 it holds into contact with the reference electrode 33. The reference electrode electrolyte holding member 36 is formed in a sheet shape (in the illustrated example, a roughly circular sheet shape) and is positioned between the reaction electrode 31 and the reference electrode 33 in the height direction H, so as to be in surface contact with the surface of the reference electrode 33. The reference electrode electrolyte holding member 36 has a larger surface area (area of ​​the surface facing the height direction H) than each of the electrodes 31, 32, and 33. The portion of the reference electrode electrolyte holding member 36 that extends in a ring shape outside the plane of each of the electrodes 31, 32, and 33 is positioned so as to be in contact with the main body portion 37a of the reaction electrode electrolyte holding member 34 and the electrolyte supply electrolyte holding member 37. The reference electrode electrolyte holding member 36 contacts the main body portion 37a of the reaction electrode electrolyte holding member 34 and the electrolyte supply electrolyte holding member 37, thereby supplying electrolyte 6 from the main body portion 37a of the electrolyte supply electrolyte holding member 37 to the reaction electrode electrolyte holding member 34. In the illustrated example, the reference electrode electrolyte holding member 36 is a substantially circular sheet, but like the electrolyte supply electrolyte holding member 37 described later, it may also comprise a sheet-shaped (for example, a substantially circular sheet) main body portion and a plurality (for example, four) sheet-shaped (for example, a substantially rectangular sheet) extension portion that protrudes out of plane from the main body portion and is arranged at substantially equal intervals from each other in the circumferential direction of the main body portion.

[0039] The electrolyte supply electrolyte holding member 37 is in direct contact with the electrolyte 6 in the electrolyte containment space CS, allowing the electrolyte 6 in the electrolyte containment space CS to permeate into the electrolyte supply electrolyte holding member 37, and supplying the permeated electrolyte 6 to the other electrolyte holding members 34, 35, and 36. The electrolyte supply electrolyte holding member 37 comprises a sheet-like main body portion 37a (in the illustrated example, a roughly circular sheet) that constitutes a part of the electrode structure 3, and a plurality of sheet-like extension portions 37b (four in the illustrated example) that protrude out of plane from the main body portion 37a and are arranged at roughly equal intervals from each other in the circumferential direction of the main body portion 37a (in the illustrated example, a roughly rectangular sheet). The electrolyte supply electrolyte holding member 37 is formed to be approximately the same shape and size as the outflow-side breathable sheet OS, and is arranged to overlap the outflow-side breathable sheet OS with the counter electrode 32 and the counter electrode electrolyte holding member 35 in between.

[0040] As shown in Figures 1 and 2, the extension portion 37b of the electrolyte supply electrolyte holding member 37 extends along the surface of the electrode structure support portion 212, through the gap between adjacent external electrode support portions 214, 214, and is bent at the outer edge of the electrode structure support portion 212 to extend into the electrolyte storage space CS. The extension portion 37b extending into the electrolyte storage space CS is in direct contact with the electrolyte 6 in the electrolyte storage space CS, supplying the electrolyte 6 from the extension portion 37b to the main body portion 37a.

[0041] Each of the electrolyte holding members 34, 35, 36, and 37 is formed of a material that is both electrically insulating and water-absorbing, and is not particularly limited; for example, it can be made of filter paper formed from silica fibers, cellulose fibers, glass fibers, etc.

[0042] The electrode structure 3 may include support sheets 38 and 39, as shown in Figures 1 and 2. The support sheets 38 and 39 are laminated within the electrode structure 3 and are used to press the reaction electrode lead wires 41, counter electrode lead wires 42, and reference electrode lead wires 43 against the reaction electrode 31, counter electrode 32, and reference electrode 33, respectively, to suppress poor contact between them. The support sheets 38 and 39 are each formed in the shape of a sheet (in the illustrated example, a substantially circular sheet) having a predetermined rigidity and are laminated between the electrolyte holding member 34 for the reaction electrode and the electrolyte holding member 36 for the reference electrode in the height direction H, and between the reference electrode 33 and the electrolyte supply electrolyte holding member 37 in the height direction H. The support sheets 38 and 39 are formed to have a surface area (area of ​​the surface facing the height direction H) that is slightly larger than that of the reaction electrode 31, counter electrode 32, and reference electrode 33, and are configured to apply pressing force to the entire surface of each of the reaction electrode 31, counter electrode 32, and reference electrode 33. Furthermore, the support sheets 38 and 39 are configured to have a smaller surface area (area of ​​the surface facing the height direction H) than the main body portion 37a of the electrolyte holding member 34 for the reaction electrode, the electrolyte holding member 36 for the reference electrode, and the electrolyte supply electrolyte holding member 37, so as not to hinder contact between the respective electrolyte holding members. The support sheets 38 and 39 can be formed from, for example, polyethylene naphthalate (PEN).

[0043] The electrolyte 6 is an electrically conductive solution that, upon contact with the electrode structure 3, generates an electrochemical reaction related to the gas to be detected. In this embodiment, as shown in Figure 2, the electrolyte 6 is contained in the electrolyte storage space CS within the case 2 so as to be in contact with the electrode structure 3 via electrolyte holding members 34, 35, 36, and 37. The electrolyte 6 can be appropriately selected depending on the type of gas to be detected and the type of electrode structure 3 used for detection. For example, an acidic aqueous solution such as sulfuric acid or phosphoric acid, or a neutral salt aqueous solution such as lithium bromide or calcium chloride can be used. Alternatively, a molten salt that is liquid at room temperature and mainly consists of nitrogen-containing aromatic cations or aliphatic onium cations and fluorine-containing anions can be used as the electrolyte 6. For example, alkylimidazolium ions or alkylpyridinium ions can be used as the nitrogen-containing aromatic cations. For example, borofluoride ions, phosphorus fluoride ions, or trifluoromethanesulfonate ions can be used as the fluorine-containing anions.

[0044] The lead wire 4 is a component that electrically connects the electrode structure 3 and the external electrode 5. In this embodiment, as shown in Figures 1 and 2, the lead wire 4 is provided with a reaction electrode lead wire 41, a counter electrode lead wire 42, and a reference electrode lead wire 43, corresponding to the reaction electrode 31, counter electrode 32, and reference electrode 33 of the electrode structure 3. The reaction electrode lead wire 41, the counter electrode lead wire 42, and the reference electrode lead wire 43 each extend along the respective surfaces of the reaction electrode 31, counter electrode 32, and reference electrode 33 at one end and are electrically connected to the respective surfaces of the reaction electrode 31, counter electrode 32, and reference electrode 33. Furthermore, the reaction electrode lead wire 41, the counter electrode lead wire 42, and the reference electrode lead wire 43 each are electrically connected at their other ends to the external reaction electrode 51, the external counter electrode 52, and the external reference electrode 53 of the external electrode 5, which will be described later.

[0045] The lead wires 41, 42, and 43 are formed in a wire or ribbon shape from a metal such as platinum, gold, tungsten, or tantalum. In this embodiment, three lead wires 41, 42, and 43 are provided, but as described above, the gas sensor 1 only needs to have at least two electrodes, namely a reaction electrode 31 and a counter electrode 32, and correspondingly at least two lead wires, namely a lead wire 41 for the reaction electrode and a lead wire 42 for the counter electrode.

[0046] The external electrode 5 applies a voltage from a control device (not shown), such as a potentiostat located outside the case 2, to the electrode structure 3 located inside the case 2 to generate an electrochemical reaction related to the gas to be detected, and transmits the electrical signal generated by the electrochemical reaction related to the gas to be detected from the electrode structure 3 to the control device. In this embodiment, as shown in Figure 1, the external electrode 5 is provided with an external electrode 51 for the reaction electrode, an external electrode 52 for the counter electrode, and an external electrode 53 for the reference electrode, corresponding to the reaction electrode 31, counter electrode 32, and reference electrode 33 of the electrode structure 3. The external electrodes 51, 52, and 53 each extend from outside the case 2 into the case 2 and are provided on the case body 21. More specifically, the external electrodes 51, 52, and 53 each extend from below the base 211 of the case body 21 along the height direction H and are provided on the external electrode support portion 214 of the case body 21 so as to protrude above the external electrode support portion 214. The external electrodes 51, 52, and 53 are electrically connected at one end (the portion protruding upward from the external electrode support portion 214) to the reaction electrode lead wire 41, the counter electrode lead wire 42, and the reference electrode lead wire 43, respectively (see Figure 3), and at the other end (the portion protruding downward from the base portion 211) to a control device (not shown). In this embodiment, as shown in Figure 4, the external electrodes 51, 52, and 53 are arranged such that the reaction electrode external electrode 51 is positioned at a distance from approximately the midpoint between the counter electrode external electrode 52 and the reference electrode external electrode 53, in a horizontal direction substantially perpendicular to the line connecting the counter electrode external electrode 52 and the reference electrode external electrode 53. In this embodiment, the external electrodes 51, 52, and 53 are provided to extend along the height direction H, but they may also be provided to extend along a direction different from the height direction H, such as the horizontal direction.

[0047] As shown in Figure 5, the external electrodes 51, 52, and 53 are positioned such that the connection points CP of the external electrodes 51, 52, and 53 to which the lead wires 41, 42, and 43 are connected are located at a height corresponding to the electrode structure 3. This allows the lead wires 41, 42, and 43 to be easily routed when connecting the electrodes 31, 32, and 33 of the electrode structure 3 to the external electrodes 51, 52, and 53 with lead wires 41, 42, and 43, as the lead wires 41, 42, and 43 only need to be routed along a nearly horizontal direction, without the need for significant bending. This makes it easy to route the lead wires 41, 42, and 43 and easily manufacture the gas sensor 1. Furthermore, since the lead wires 41, 42, and 43 are not significantly bent, the risk of breakage due to stress on the bent portion of the lead wires 41, 42, and 43 is suppressed. In this specification, "corresponding height" means a position in the height direction H that is approximately the same as that of the object to be compared (e.g., electrode structure 3 and electrodes 31, 32, 33) with respect to the reference position of the case body 21 (e.g., the base 211 or the surface of the electrode structure support part 212), but it may also include positions in the height direction H that are shifted by approximately the length of the object to be compared. When the connection points CP of the external electrodes 51, 52, and 53 are located at a height corresponding to the electrode structure 3, it means that at least one of the connection points CP of the external electrodes 51, 52, and 53 is located at a height corresponding to the range of height direction H of the electrode structure 3. For example, at least one of the connection points CP of the external electrodes 51, 52, and 53 may be located at a height corresponding to any of the electrodes 31, 32, and 33 included in the electrode structure 3, or each of the connection points CP of the external electrodes 51, 52, and 53 may be located at a height corresponding to the electrodes 31, 32, and 33 that correspond to the external electrodes 51, 52, and 53, respectively.

[0048] In this embodiment, the external electrodes 51, 52, and 53 are arranged such that their connection points CP (position in the height direction H) are approximately the same, as shown in Figure 5. This eliminates the need to change or bend the placement height of the corresponding lead wires 41, 42, and 43 according to the external electrodes 51, 52, and 53, allowing for easy routing of the lead wires 41, 42, and 43 and easy manufacturing of the gas sensor 1. In this embodiment, the connection points CP of the external electrodes 51, 52, and 53, which are approximately the same height, are located at the height corresponding to the reaction electrode 31 of the electrode structure 3, as shown in Figure 5. However, the heights of the connection points CP of the external electrodes 51, 52, and 53 may be different, as long as at least one of them is located at the height corresponding to the electrode structure 3.

[0049] The external electrodes 51, 52, and 53 are each formed in the shape of a rod from a metal such as platinum, gold, tungsten, or tantalum. In this embodiment, three external electrodes 51, 52, and 53 are provided, but as described above, the gas sensor 1 only needs to have at least two electrodes, namely the reaction electrode 31 and the counter electrode 32, and correspondingly, it only needs to have at least two external electrodes, namely the external electrode 51 for the reaction electrode and the external electrode 52 for the counter electrode.

[0050] In this embodiment, as shown in Figures 3 and 4, the case body 21 is equipped with a guide section 7 that guides the lead wires 41, 42, and 43 along an introduction path from outside the case body 21 to the electrode structure 3 via the connection points CP of the external electrodes 51, 52, and 53. This allows for easy routing of the lead wires 41, 42, and 43 from outside the case body 21 between the connection points CP of the external electrodes 51, 52, and 53 and the electrodes 31, 32, and 33 of the electrode structure 3 when connecting the electrodes 31, 32, and 33 of the electrode structure 3 with the lead wires 41, 42, and 43, thus enabling easy manufacturing of the gas sensor 1. The guide section 7 is positioned such that the introduction path is located at a height corresponding to the connection points CP of the external electrodes 51, 52, and 53 and the electrode structure 3, which are located at corresponding heights to each other. This allows the lead wires 41, 42, and 43 to be introduced from outside the case body 21 and positioned between the electrode structure 3 and the connection point CP of the external electrodes 51, 52, and 53, while also facilitating the positioning of the lead wires 41, 42, and 43 in the height direction H. The description of "introduction path toward the electrode structure 3 via the connection point CP of the external electrodes 51, 52, and 53" refers not only to the positions of the connection point CP and electrode structure 3 already in place when the lead wires 41, 42, and 43 are guided, but also to the virtual positions of the connection point CP and electrode structure 3 that are positioned after the lead wires 41, 42, and 43 have been guided. In this embodiment, the guide section 7 is provided on the upper external electrode support section 214b where the connection point CP of the external electrodes 51, 52, and 53 is positioned, as described above. However, the guide section 7 only needs to be positioned to guide the lead wires 41, 42, and 43 along the introduction path described above, and may be provided in any part of the case body 21 other than the upper external electrode support section 214b.

[0051] The guide section 7 is not particularly limited in its configuration, as long as it can guide the lead wires 41, 42, and 43 along an introduction path from outside the case body 21 toward the electrode structure 3 via the connection points CP of the external electrodes 51, 52, and 53. In this embodiment, as shown in Figures 3 and 4, the guide section 7 includes a first guide section 71 that guides the lead wires 41, 42, and 43 from outside the case body 21 toward the connection points CP of the external electrodes 51, 52, and 53, and a second guide section 72 that guides the lead wires 41, 42, and 43 from the connection points CP of the external electrodes 51, 52, and 53 toward the electrode structure 3. In this way, by providing the first and second guide sections 71 and 72 on both sides of the connection points CP of the external electrodes 51, 52, and 53 in the introduction path from outside the case body 21 toward the electrode structure 3, the lead wires 41, 42, and 43 can be routed more accurately to the connection points CP of the external electrodes 51, 52, and 53. Furthermore, in this embodiment, the first and second guide sections 71 and 72 are arranged in a substantially straight line along the introduction path from outside the case body 21 through the connection points CP of the external electrodes 51, 52, and 53 toward the electrode structure 3. This allows the lead wires 41, 42, and 43 to be positioned in a substantially straight line when arranging them between the connection points CP of the external electrodes 51, 52, and 53 and the electrode structure 3, making it easier to arrange the lead wires 41, 42, and 43. For example, when introducing the lead wires 41, 42, and 43 from outside the case body 21, the lead wires 41, 42, and 43 may be introduced in a state where they are cut to a predetermined length, i.e., a length corresponding to the distance between each electrode 31, 32, and 33 of the electrode structure 3 and each connection point CP of the external electrodes 51, 52, and 53, or they may be introduced in a state longer than the predetermined length and cut after being connected to the connection points CP of the external electrodes 51, 52, and 53.In the latter case, for example, the lead wires 41, 42, and 43 wound on a reel are guided in the order of the first guide section 71 and the second guide section 72, and when the tips of the lead wires 41, 42, and 43 reach the electrode structure 3, the lead wires 41, 42, and 43 are fixed by chucks or the like on the outside of the first guide section 71 (outside the case body 21) and the outside of the second guide section 72 (on the electrode structure 3 side), and after joining the lead wires 41, 42, and 43 to the external electrodes 51, 52, and 53 at each connection point CP by welding or the like, the lead wires 41, 42, and 43 can be positioned in the predetermined location by cutting them on the outside of the first guide section 71 or between the first guide section 71 and each connection point CP. In this way, the routing of the lead wires 41, 42, and 43 can be automated while suppressing misalignment of the lead wires 41, 42, and 43.

[0052] In this embodiment, the first guide section 71 is positioned at a height corresponding to the connection points CP of the external electrodes 51, 52, and 53, as shown in Figure 5. More specifically, the bottom surface of the first guide section 71, which will be described later, is positioned at a height corresponding to the connection points CP of the external electrodes 51, 52, and 53. This allows the lead wires 41, 42, and 43 to be positioned at the connection points CP of the external electrodes 51, 52, and 53 by introducing the lead wires 41, 42, and 43 from outside the case body 21 toward the connection points CP of the external electrodes 51, 52, and 53, by introducing the lead wires 41, 42, and 43 along a substantially horizontal direction. In this embodiment, as described above, the heights (positions in the height direction H) of the connection points CP of the external electrodes 51, 52, and 53 are substantially the same, so the first guide sections 71 for each lead wire 41, 42, and 43 are positioned at substantially the same height. However, if the connection points CP of the external electrodes 51, 52, and 53 are located at different heights, the first guide portion 71 may be positioned at a height corresponding to the connection point CP of each external electrode 51, 52, and 53, or it may be inclined horizontally from the outside of the case body 21 toward the connection point CP of each external electrode 51, 52, and 53.

[0053] In this embodiment, the second guide portion 72 is positioned at a height corresponding to the connection point CP of the external electrodes 51, 52, and 53 and the electrode structure 3, as shown in Figure 5. More specifically, the bottom surface of the second guide portion 72, which will be described later, is positioned at a height corresponding to the connection point CP of the external electrodes 51, 52, and 53 and the electrode structure 3. This allows the lead wires 41, 42, and 43 to be positioned in the electrode structure 3 by introducing them along a substantially horizontal direction when introducing the lead wires 41, 42, and 43 from the connection point CP of the external electrodes 51, 52, and 53 toward the electrode structure 3. In this embodiment, since the electrodes 31, 32, and 33 of the electrode structure 3 are stacked along the height direction H, they are located at different heights within the electrode structure 3. In this embodiment, as shown in Figure 5, all of the second guide portions 72 for each electrode 31, 32, and 33 are positioned at a height corresponding to the reaction electrode 31, which is located at the highest position among the electrodes 31, 32, and 33. This allows the lead wires 41, 42, and 43 to be introduced in a substantially horizontal direction in the same manner, regardless of which electrode 31, 32, or 33 they are routed for. However, the second guide portion 72 may be positioned at a height corresponding to each of the electrodes 31, 32, and 33, depending on the position of each electrode in the height direction H, as shown in Figure 6, for example. More specifically, the bottom surface of the second guide portion 72 may be positioned at a height corresponding to the surface of each electrode 31, 32, and 33, depending on the position of each electrode in the height direction H. This reduces the degree of curvature of the lead wires 41, 42, and 43 caused by the height difference between the connection points CP of the external electrodes 51, 52, and 53 and each of the electrodes 31, 32, and 33, thereby reducing the load on the lead wires 41, 42, and 43. Alternatively, for the same purpose, the second guide portion 72 may be inclined to correspond to the height difference between the connection points CP of the external electrodes 51, 52, and 53 and the electrodes 31, 32, and 33, respectively, as shown in Figure 7. More specifically, the bottom surface of the second guide portion 72 may be inclined to correspond to the height difference between the connection points CP of the external electrodes 51, 52, and 53 and the electrodes 31, 32, and 33, respectively.

[0054] In this embodiment, the case body 21, as shown in Figures 3 and 4, is provided with a wall W formed around the horizontal connection points CP of the external electrodes 51, 52, and 53. The first guide portion 71 is composed of the peripheral wall of a first recess WR1 provided on the wall W opposite to the electrode structure 3 in the introduction path of the lead wires 41, 42, and 43, and the second guide portion 72 is composed of the peripheral wall of a second recess WR2 provided on the wall W on the side of the electrode structure 3 in the introduction path of the lead wires 41, 42, and 43. The first and second recesses WR1 and WR2 each penetrate the wall W along the introduction path of the lead wires 41, 42, and 43, and are formed by a bottom surface that demarcates the lower end in the height direction H and side surfaces that demarcate both sides in the horizontal direction perpendicular to the direction in which the introduction path of the lead wires 41, 42, and 43 extends, and open at the upper end in the height direction H. The bottom and side surfaces defining the first and second recesses WR1 and WR2, respectively, constitute the peripheral walls of the first and second recesses WR1 and WR2 and function as guide surfaces against which the lead wires 41, 42, and 43 abut. In this embodiment, the bottom and side surfaces defining the first and second recesses WR1 and WR2, respectively, are formed substantially parallel to the direction in which the introduction paths for the lead wires 41, 42, and 43 extend. The shape of the first and second recesses WR1 and WR2 is not particularly limited, as long as the distance between the side surfaces facing each of the first and second recesses WR1 and WR2 is at least greater than the outer diameter of the lead wires 41, 42, and 43. In the illustrated example, the first and second recesses WR1 and WR2 are formed in a substantially funnel shape such that the distance between the side surfaces is constant below the height direction H and increases towards the opening at the upper end above the height direction H. This makes it easier to insert the lead wires 41, 42, and 43 into the first and second guide portions 71 and 72 from the upper side of the case body 21 in the height direction H, and makes it easier to position the lead wires 41, 42, and 43 between the electrode structure 3 and the connection point CP of the external electrodes 51, 52, and 53.

[0055] In this embodiment, the case body 21, as shown in Figures 3 and 4, has a holding structure 8 that can hold a predetermined amount of protective agent PA (see Figures 11 and 12) to cover the connection points CP of each of the external electrodes 51, 52, and 53. By providing such a holding structure 8, the connection points CP can be protected by the protective agent PA, and corrosion of the connection points CP by the electrolyte 6 can be suppressed. Furthermore, since the holding structure 8 can hold a predetermined amount of protective agent PA, it facilitates the control of the amount of protective agent PA applied to the connection points CP, and promotes the automation of the manufacturing of the gas sensor 1. In addition, the holding structure 8 is provided corresponding to the connection points CP of the external electrodes 51, 52, and 53 which are located at a height corresponding to the electrode structure 3, and thereafter the holding structure 8 is located at a height corresponding to the electrode structure 3 and the connection points CP of the external electrodes 51, 52, and 53, or at a height near or above that height. Therefore, after arranging the electrodes 31, 32, and 33 of the electrode structure 3 and placing the lead wires 41, 42, and 43 between the electrodes 31, 32, and 33 and the connection points CP of the external electrodes 51, 52, and 53, the protective agent PA can be applied to the connection points CP of the external electrodes 51, 52, and 53. This eliminates the need to wait for time for the protective agent to dry or harden during the manufacturing process, unlike conventional techniques where the electrodes must be arranged and the lead wires routed after the protective agent has been applied to the connection points of the external electrodes. Furthermore, unlike conventional techniques where the connection points of the external electrodes are located on the bottom surface of the case body, it is not necessary to insert the application device for applying the protective agent PA deep into the case body 21 below the position where the electrode structure 3 is installed, allowing easy access to the holding structure 8, and thus the protective agent PA can be easily applied.

[0056] The retaining structure 8 only needs to be able to hold a predetermined amount of protective agent PA so as to cover the connection points CP of the external electrodes 51, 52, and 53, and its structure is not particularly limited. In this embodiment, as shown in Figures 3 and 4, the retaining structure 8 includes a wall portion W formed around the horizontal periphery of the connection points CP of the external electrodes 51, 52, and 53. The wall portion W is provided around the entire horizontal periphery of the connection points CP and extends above the connection points CP in the height direction H. The retaining structure 8 can hold a predetermined amount of protective agent PA with the wall portion W formed around the horizontal periphery of the connection points CP, and can protect the connection points CP with the predetermined amount of protective agent PA. In this embodiment, the retaining structure 8 includes a wall portion W formed around the connection points CP and a bottom portion B that closes the space surrounded by the wall portion W at the lower end of the wall portion W, and is formed in the shape of a bottomed cylinder. External electrodes 51, 52, and 53 each protrude from the surface of the bottom B that forms the holding structure 8, and connection points CP are formed at the upper ends of the protruding external electrodes 51, 52, and 53, to which they are connected to lead wires 41, 42, and 43, respectively.

[0057] In this embodiment, the retaining structure 8 includes a guide section 7 that guides the lead wires 41, 42, and 43 along an introduction path from outside the case body 21 to the electrode structure 3 via the connection points CP of the external electrodes 51, 52, and 53, as shown in Figures 3 and 4. By including the guide section 7 in the retaining structure 8, the guidance of the lead wires 41, 42, and 43 from outside the case body 21 to the electrode structure 3, the placement of the lead wires 41, 42, and 43 between the electrode structure 3 and the connection points CP of the external electrodes 51, 52, and 53, the connection of the lead wires 41, 42, and 43 to the connection points CP of the external electrodes 51, 52, and 53, and the filling of the retaining structure 8 with the protective agent PA can all be performed at substantially the same location without requiring the rearrangement of the lead wires 41, 42, and 43.

[0058] The protective agent PA covers the connection points CP of the external electrodes 51, 52, and 53, thereby preventing the electrolyte 6 from coming into contact with the connection points CP and preventing corrosion of the connection points CP by the electrolyte 6. The protective agent PA only needs to be able to protect the connection points CP of the external electrodes 51, 52, and 53 from the electrolyte 6 and is not particularly limited, but from the viewpoint of ease of filling into the holding structure 8, it is preferable that it be a thermosetting resin that is in an uncured state before filling and can be cured after filling, and from the viewpoint of preventing overflow from the holding structure 8, it is even more preferable that it be a thermosetting resin that has a viscosity of a predetermined level or higher in the uncured state, for example epoxy resin adhesive is an example.

[0059] Next, the manufacturing method of the gas sensor 1 of this embodiment will be described with reference to the attached drawings, particularly Figures 8 to 12. However, the following description is merely an example, and the gas sensor and the method for manufacturing the gas sensor of the present invention are not limited to the following example. Also, although several steps will be described in order below, these steps may be performed simultaneously or in a different order. Note that in Figures 8 to 12, the other components of the electrode structure 3 are omitted from the illustration in order to make the arrangement of electrodes 31, 32, and 33 of the electrode structure 3 easier to understand.

[0060] The manufacturing method of the gas sensor 1 in this embodiment includes the step of providing a case body 21, as shown in Figure 8. External electrodes 51, 52, and 53 are fixed to the case body 21. In this embodiment, the case body 21 and the external electrodes 51, 52, and 53 are integrally molded, so the step of assembling the separately formed case body 21 and external electrodes 51, 52, and 53 can be omitted. Furthermore, an outflow-side buffer membrane OB and an outflow-side breathable sheet OS (see Figures 1 and 2) are laminated onto the case body 21, and the outflow-side breathable sheet OS is fixed to the case body 21 by heat fusion.

[0061] The manufacturing method includes, as shown in Figure 8, the step of providing the electrode structure 3 to the case body 21. In this step, first, the counter electrode 32 of the electrode structure 3 is provided to the case body 21. In this embodiment, the counter electrode 32 is laminated on the surface of the outflow side breathable sheet OS. The reference electrode 33 and reaction electrode 31 of the electrode structure 3 are laminated on top of the counter electrode 32 in parallel with the subsequent steps or after the subsequent steps. However, the electrodes 31, 32, and 33 may be laminated in a different order.

[0062] The manufacturing method includes, as shown in Figure 8, the next step of introducing lead wires 41, 42, and 43 along an introduction path from outside the case body 21 towards the electrode structure 3 via connection points CP of the external electrodes 51, 52, and 53. In the example in Figure 8, the counter electrode lead wire 42 is introduced from outside the case body 21 towards the electrode structure 3 via connection point CP of the counter electrode external electrode 52. By introducing the counter electrode lead wire 42 from outside the case body 21 towards the electrode structure 3 via connection point CP, the introduction of the counter electrode lead wire 42 from outside the case body 21 and the subsequent placement of the counter electrode lead wire 42 between the electrode structure 3 and connection point CP can be carried out in a series of steps. In this embodiment, since the connection point CP is located at a height corresponding to the electrode structure 3, the counter electrode lead wire 42 can be introduced along a substantially horizontal direction, and the introduction of the counter electrode lead wire 42 can be easily performed by mechanical operation. Furthermore, in this embodiment, a guide section 7 is provided for guiding the counter electrode lead wire 42, making it easy and accurate to route the counter electrode lead wire 42. Alternatively, instead of introducing the counter electrode lead wire 42 to the electrode structure 3 via the connection point CP along the introduction path described above, it may be introduced, for example, from the upper side of the case body 21 towards both the connection point CP and the electrode structure 3.

[0063] The manufacturing method includes, as shown in Figure 9, a step of arranging lead wires 41, 42, and 43 between the surfaces of electrodes 31, 32, and 33 and the connection points CP of the external electrodes 51, 52, and 53. In the example in Figure 9, the counter electrode lead wire 42 is arranged between the surface of the counter electrode 32 and the connection point CP of the counter electrode external electrode 52. In this step, the counter electrode lead wire 42 only needs to be located at least above the height H of the surface of the counter electrode 32, and may be in contact with the surface of the counter electrode 32 as shown in Figure 9, or it may be slightly floating above the surface of the counter electrode 32. In this embodiment, this step is performed before the counter electrode lead wires 42 are connected to the counter electrode 32 and the counter electrode external electrode 52.

[0064] The manufacturing process includes, as shown in Figure 9, a step of connecting the lead wires 41, 42, 43 to the external electrodes 51, 52, 53 at the connection point CP, while the lead wires 41, 42, 43 are positioned on the surfaces of the electrodes 31, 32, 33. If lead wires longer than a predetermined length, such as lead wires wound on a reel, are used as lead wires 41, 42, 43, the process may include a step of cutting the lead wires 41, 42, 43 at a predetermined position (for example, outside the first guide portion 71, between the first guide portion 71 and the connection point CP) after the step of connecting the lead wires 41, 42, 43 to the external electrodes 51, 52, 53, while the lead wires 41, 42, 43 are positioned on the surfaces of the electrodes 31, 32, 33. In the example shown in Figure 9, the counter electrode lead wire 42 is positioned on the surface of the counter electrode 32 and connected to the counter electrode external electrode 52 at the connection point CP. The connection between the counter electrode lead wire 42 and the counter electrode external electrode 52 is performed by welding or the like. In the conventional technology, it was necessary to connect one end of the lead wire to the external electrode and then bend the lead wire so that the other end of the lead wire was positioned on the electrode, which made the wiring of the lead wire difficult. However, in this embodiment, the counter electrode lead wire 42 is positioned on the surface of the counter electrode 32 and connected to the counter electrode external electrode 52, so such complicated wiring is not necessary. In this step as well, the counter electrode lead wire 42 only needs to be positioned at least above the height H of the surface of the counter electrode 32, and may be in contact with the surface of the counter electrode 32 as shown in Figure 9, or it may be slightly floating above the surface of the counter electrode 32. As shown in Figure 10, in a subsequent step, the counter electrode lead wire 42 is pressed onto the surface of the counter electrode 32 and connected so as to extend along the surface of the counter electrode 32 when other components are stacked on top of the counter electrode 32 and the case body 21 is closed with the case cover 22 (see Figures 1 and 2).

[0065] Next, in this embodiment, the counter electrode electrolyte holding member 35, the electrolyte supply electrolyte holding member 37, and the support sheet 39 (see Figures 1 and 2) are stacked in order above the counter electrode 32, and then the reference electrode 33 is stacked as shown in Figure 10. Then, the reference electrode lead wire 43 is introduced along an introduction path from outside the case body 21 towards the electrode structure 3 via the connection point CP (see Figures 3 and 4) of the reference electrode external electrode 53, in the same manner as the counter electrode lead wire 42. The reference electrode lead wire 43 is positioned between the surface of the reference electrode 33 and the connection point CP of the reference electrode external electrode 53, and then, while positioned on the surface of the reference electrode 33, it is connected to the reference electrode external electrode 53 at the connection point CP of the reference electrode external electrode 53. The method of connecting the reference electrode lead wire 43 to the reference electrode external electrode 53 and the reference electrode 33 is carried out in the same manner as the counter electrode lead wire 42.

[0066] Next, in this embodiment, the electrolyte holding member 36 for the reference electrode, the support sheet 38, and the electrolyte holding member 34 for the reaction electrode are stacked in order above the reference electrode 33 (see Figures 1 and 2). Then, as shown in Figure 11, the lead wire 41 for the reaction electrode is introduced along an introduction path from outside the case body 21 towards the electrode structure 3 via the connection point CP of the external electrode 51 for the reaction electrode, in the same manner as the lead wire 42 for the counter electrode and the lead wire 43 for the reference electrode. The lead wire 41 for the reaction electrode is positioned between the virtual surface of the reaction electrode 31 (see Figure 12) that will be placed thereafter and the connection point CP of the external electrode 51 for the reaction electrode, and then connected to the external electrode 51 for the reaction electrode at the connection point CP while positioned on the virtual surface of the reaction electrode 31 that will be placed thereafter. In this embodiment, the lead wire 41 for the reaction electrode is positioned on the virtual surface of the reaction electrode 31 that will be placed thereafter, but it may also be positioned on the surface of the reaction electrode 31 that is actually placed thereafter. The connection of the reaction electrode lead wire 41 to the reaction electrode external electrode 51 is carried out in the same manner as the counter electrode lead wire 42 and the reference electrode lead wire 43.

[0067] The manufacturing process may also include, as shown in Figure 11, a step of supplying a predetermined amount of protective agent PA to the holding structure 8 so as to cover the connection points CP of the external electrodes 51, 52, and 53 with the protective agent PA. By covering the connection points CP of the external electrodes 51, 52, and 53 with the protective agent PA, corrosion by the electrolyte 6 is suppressed. Since the holding structure 8 is configured to hold a predetermined amount of protective agent PA, it becomes easy to control the amount of protective agent PA when supplying it.

[0068] Next, as shown in Figure 12, the reaction electrode 31 is stacked on the electrolyte holding member 34 for the reaction electrode (see Figures 1 and 2) and the lead wires 41 for the reaction electrode, so that the lead wires 41 are connected so that they extend along the surface of the reaction electrode 31. In this embodiment, the reaction electrode 31 is fixed to the case cover 22 via the breathable sheet 31b, which is fixed to the case cover 22. Therefore, by closing the case body 21 with the case cover 22, the reaction electrode 31 is stacked on the electrolyte holding member 34 for the reaction electrode and the lead wires 41 for the reaction electrode.

[0069] The case cover 22 is fixed to the case body 21 by known bonding means such as ultrasonic welding or adhesive. Finally, the electrolyte 6 (see Figure 2) is supplied to the electrolyte containment space CS inside the case 2, which is formed when the case cover 22 is fixed to the case body 21.

[0070] Next, the gas sensors 1 of the second and third embodiments, which are modified versions of the gas sensor 1 of the first embodiment described above, will be explained using Figures 13 to 16. The gas sensors 1 of the second and third embodiments differ from the gas sensor 1 of the first embodiment mainly in that the electrodes of the electrode structure 3 include at least two reaction electrodes for detecting different target gases, and accordingly, the lead wires 4 and external electrodes 5 each include at least two reaction electrode lead wires and at least two reaction electrode external electrodes. Hereafter, the explanation of matters common to the gas sensor 1 of the first embodiment described above will be omitted, and the explanation will focus on the differences. Also, components that have the same function as the components of the gas sensor 1 of the first embodiment will be described using the same reference numerals. All matters described with respect to the gas sensor 1 of the first embodiment can be applied to the gas sensors 1 of the second and third embodiments to the extent that the objective of the invention can be achieved. Furthermore, the effects obtained by the configuration described for the gas sensor 1 of the first embodiment can also be obtained for the gas sensors 1 of the second and third embodiments, insofar as they have the same configuration.

[0071] <Second Embodiment> In the gas sensor 1 of the second embodiment, as shown in Figures 13 and 14, the electrodes of the electrode structure 3 include two reaction electrodes 31, 311 for detecting different target gases, one counter electrode 32, and one reference electrode 33. In this embodiment, one counter electrode 32 and one reference electrode 33 are used in common for the two reaction electrodes 31, 311. However, the electrodes of the electrode structure 3 may include two counter electrodes corresponding to each of the two reaction electrodes 31, 311. In that case, the two counter electrodes 32 can be formed, for example, by depositing two electrode materials (for example, approximately semicircular) on a single breathable sheet (for example, approximately circular) with a slit-like gap between them, or they can be formed separately from each other. When the electrodes of the electrode structure 3 include a total of five electrodes, two reaction electrodes, two counter electrodes, and one reference electrode, the sensor 1 can also be formed using Case 2 of the third embodiment, which will be described later, and similarly includes a total of five electrodes. The gas sensor 1 can detect a first target gas, such as oxygen gas, using one of the two reaction electrodes 31, 311 (hereinafter also referred to as the "first reaction electrode 31"), and can detect a second target gas, such as hydrogen sulfide gas or carbon monoxide gas, using the other reaction electrode 311 (hereinafter also referred to as the "second reaction electrode 311"). In this embodiment, the electrode structure 3 includes two reaction electrodes 31, 311, but it is sufficient to include at least two reaction electrodes for the purpose of detecting different target gases, and may include three reaction electrodes, as in the gas sensor 1 of the third embodiment shown below, or it may include more than three reaction electrodes. If the electrode structure 3 includes at least two reaction electrodes, it may also include at least two counter electrodes corresponding to each of the at least two reaction electrodes.

[0072] The first reaction electrode 31 and the second reaction electrode 311 are arranged so as not to overlap with each other when viewed in the height direction H, as shown in Figure 13. More specifically, the first reaction electrode 31 is stacked with the counter electrode 32 and the reference electrode 33 in the height direction H, and the second reaction electrode 311 is positioned spaced apart from the first reaction electrode 31, the counter electrode 32, and the reference electrode 33 in a direction perpendicular to the height direction H (horizontal direction). This allows for independent external gas supply to each of the reaction electrodes 31 and 311. If the electrode structure includes three or more reaction electrodes, the three or more reaction electrodes are positioned spaced apart from each other in a direction perpendicular to the height direction H (horizontal direction). The height H of the two reaction electrodes 31 and 311 relative to each other is not particularly limited, but in this embodiment, the second reaction electrode 311 is positioned at a height corresponding to the first reaction electrode 31 by fixing the first and second reaction electrodes 31 and 311 to the upper wall of the case cover 22. If the electrode structure includes three or more reaction electrodes, the three or more reaction electrodes are positioned at corresponding heights to each other. In this embodiment, the first reaction electrode 31 and the second reaction electrode 311 have the same configuration as the reaction electrode 31 described with respect to the gas sensor 1 of the first embodiment, and have the same configuration as each other, but they may have a different configuration from the reaction electrode 31 in the first embodiment, or they may have different configurations from each other.

[0073] In the electrode structure 3, which includes two reaction electrodes 31 and 311, the electrolyte holding member 34 for the reaction electrodes, which is laminated on the two reaction electrodes 31 and 311, is formed in a shape and size that contacts both surfaces of the two reaction electrodes 31 and 311, as shown in Figure 13. This allows one electrolyte holding member 34 to supply electrolyte 6 to both reaction electrodes 31 and 311. In this embodiment, the electrolyte holding member 34 for the reaction electrodes is formed in a sheet shape with a shape and size that fits the first electrode structure support space SS and the second electrode structure support space SS1 of the case body 21, which will be described later. Similarly, the electrolyte holding member 36 for the reference electrode is also formed in a sheet shape with substantially the same shape and size as the electrolyte holding member 34 for the reaction electrode. In this embodiment, the electrolyte holding member 35 for the counter electrode is formed in a substantially circular sheet shape that fits the first electrode structure support space SS, but it may also be formed in a sheet shape with substantially the same shape and size as the electrolyte holding member 34 for the reaction electrode. Furthermore, the support sheets 38 and 39, which can be optionally stacked within the electrode structure 3, have substantially the same shape as the electrolyte holding member 34 for the reaction electrode and the electrolyte holding member 36 for the reference electrode, but are formed to be smaller in size than the electrolyte holding member 34 for the reaction electrode and the electrolyte holding member 36 for the reference electrode, so as not to hinder contact between the electrolyte holding members.

[0074] The electrolyte supply and holding member 37, which is laminated within the electrode structure 3, comprises a sheet-like main body portion 37a and two sheet-like extension portions 37b, 37b that project from the main body portion 37a out of plane and in opposite directions on substantially the same straight line, as shown in Figure 13. The main body portion 37a is formed to fit into the first electrode structure support space SS on the electrode structure support portion 212, which will be described later, and also to fit into the main body groove portion 2121a (see Figure 14) of the electrode structure support portion 212, which will be described later. The main body portion 37a is laminated in the first electrode structure support space SS with the first reaction electrode 31, counter electrode 32, and reference electrode 33 (and the electrolyte holding members for each electrode). In addition, each of the two extension portions 37b, 37b is formed to fit into the extension groove portion 2121b (see Figure 14) of the electrode structure support portion 212, which will be described later. The two extensions 37b, 37b extend in opposite directions relative to the electrode structure support portion 212 of the case body 21, are bent at the outer edge of the electrode structure support portion 212, and are positioned opposite each other in the electrolyte containment space CS (see also Figure 2). A portion of one of the two extensions 37b, 37b is partially laminated with the second reaction electrode 311 (as well as the electrolyte holding member 34 for the reaction electrode and the electrolyte holding member 36 for the reference electrode) in the second electrode structure support space SS1.

[0075] The gas sensor 1 of this embodiment includes, corresponding to the presence of two reaction electrodes 31 and 311, two reaction electrode lead wires 41 and 411 connected to each of the two reaction electrodes 31 and 311, and two reaction electrode external electrodes 51 and 511 connected to each of the two reaction electrode lead wires 41 and 411, as shown in Figures 13 and 14. In other words, in the gas sensor 1 of this embodiment, the lead wire 4 includes the two reaction electrode lead wires 41 and 411, a counter electrode lead wire 42 connected to the counter electrode 32, and a reference electrode lead wire 43 connected to the reference electrode 33. The external electrode 5 includes two reaction electrode external electrodes 51 and 511, a counter electrode external electrode 52 connected to the counter electrode lead wire 42, and a reference electrode external electrode 53 connected to the reference electrode lead wire 43. The two external electrodes 51 and 511 for the reaction electrodes are positioned such that their connection points CP are located at heights corresponding to the two reaction electrodes 31 and 311. This allows both reaction electrode lead wires 41 and 411 to be routed along a substantially horizontal direction when connecting the two reaction electrodes 31 and 311 to the two external electrodes 51 and 511 with the two reaction electrode lead wires 41 and 411, without the need for significant bending. This makes it easy to route the two reaction electrode lead wires 41 and 411 and to manufacture the gas sensor 1. If the electrode structure includes three or more reaction electrodes, three or more reaction electrode lead wires and three or more reaction electrode external electrodes are provided corresponding to each of the three or more reaction electrodes. In this case, the three or more reaction electrode external electrodes are positioned such that their connection points are located at heights corresponding to the three or more reaction electrodes. However, notwithstanding the foregoing, the external electrode for the reaction electrode may be positioned such that the connection point of the external electrode for the reaction electrode is located at a different height from the reaction electrode.

[0076] In the gas sensor 1 of this embodiment, case 2 has a different configuration from case 2 of the gas sensor 1 of the first embodiment in order to accommodate an additional second reaction electrode 311, a lead wire 411 for the second reaction electrode, and an external electrode 511 for the second reaction electrode compared to the gas sensor 1 of the first embodiment. The case body 21 of case 2 in this embodiment includes, as shown in Figures 13 and 14, two external electrode support parts 214, 214 for supporting one external electrode each (in this embodiment, the external electrode 51 for the first reaction electrode and the external electrode 53 for the reference electrode, respectively), and one external electrode support part 214 for supporting two external electrodes (in this embodiment, the external electrode 511 for the second reaction electrode and the external electrode 52 for the counter electrode). Each external electrode support section 214, 214 for supporting one external electrode 51, 53 is provided with one guide section 7 and one holding structure section 8, while each external electrode support section 214 for supporting two external electrodes 511, 52 is provided with two guide sections 7, 7 and two holding structure sections 8, 8. A partition wall W1 is provided between these two holding structure sections 8, 8, thereby limiting the amount of protective agent PA used for the connection points CP of the external electrodes 511, 52 to a predetermined amount. Regardless of the illustrated example, the guide section 7 may have a structure similar to the guide section 7 of the gas sensor 1 of the first embodiment. The number, shape, and arrangement of the external electrode support sections, guide sections, and holding structure sections can be appropriately modified according to the number, shape, and arrangement of the reaction electrode, counter electrode, reference electrode, and external electrodes.

[0077] In this embodiment, the case body 21 has, as shown in Figures 13 and 14, a first electrode structure support space SS surrounded by three external electrode support parts 214 near the horizontal center of the electrode structure support part 212 on the surface of the electrode structure support part 212, and a second electrode structure support space SS1 between two adjacent external electrode support parts 214, 214 along the periphery of the first electrode structure support space SS. The first reaction electrode 31, counter electrode 32, and reference electrode 33 (and electrolyte holding members for each electrode) are supported in the first electrode structure support space SS, and the second reaction electrode 311 (and electrolyte holding member 34 for the reaction electrode and electrolyte holding member 36 for the reference electrode) are supported in the second electrode structure support space SS1. In this embodiment, the first electrode structure support space SS is formed to have the same shape and size as the electrode structure support space SS described for the gas sensor 1 of the first embodiment, but it may be formed to have a different shape and size than the electrode structure support space SS of the first embodiment.

[0078] As shown in Figure 14, the electrode structure support portion 212 of the case body 21 has a groove portion 2121 into which the outflow side breathable sheet OS and the electrolyte supply electrolyte holding member 37 are arranged. The groove portion 2121 is formed in a shape and size that allows the outflow side breathable sheet OS and the electrolyte supply electrolyte holding member 37 to be inserted. The groove portion 2121 includes a main groove portion 2121a into which the main body portion OS1 of the outflow side breathable sheet OS and the main body portion 37a of the electrolyte supply electrolyte holding member 37 can be inserted, and two extension groove portions 2121b, 2121b into which the extension portion OS2 of the outflow side breathable sheet OS and the extension portion 37b of the electrolyte supply electrolyte holding member 37 can be inserted. The main groove portion 2121a is provided below the first electrode structure support space SS, and one of the two extension groove portions 2121b, 2121b is provided in a part below the second electrode structure support space SS1. The second reaction electrode 311, supported in the second electrode structure support space SS1, is positioned to straddle the edge of the extension groove 2121b in a direction perpendicular to the extension direction of the extension groove 2121b.

[0079] The outlet-side permeable sheet OS, positioned in the groove 2121 of the electrode structure support portion 212, comprises a sheet-like main body portion OS1 and two sheet-like extension portions OS2, OS2 projecting from the main body portion OS1 out of plane and in opposite directions on a substantially straight line, as shown in Figure 13. The two extension portions OS2, OS2 extend in opposite directions relative to the electrode structure support portion 212 of the case body 21 along the extension groove portion 2121b of the groove 2121, and are bent at the outer edge of the electrode structure support portion 212 to be positioned opposite each other in the electrolyte containment space CS (see also Figure 2). For example, if the gas sensor 1 is tilted toward one of the two extension portions OS2, OS2, the entirety of one extension portion OS2 in the electrolyte containment space CS becomes immersed in the electrolyte 6, making it difficult for the gas in the electrolyte containment space CS to be discharged to the outside of the case 2 through the extension portion OS2. However, even if that were to happen, since the other of the two extensions OS2 is not immersed in the electrolyte 6 at least partially (near the boundary between the electrode structure support 212 and the electrolyte storage space CS), the gas in the electrolyte storage space CS can be discharged to the outside of the case 2 through the other extension OS2. In the gas sensor 1 of this embodiment, by providing an outlet-side permeable sheet OS having two extensions OS2, OS2 extending substantially in the same straight line in opposite directions, even if the gas sensor 1 is tilted, the gas in the electrolyte storage space CS can be discharged to the outside of the case 2, thereby maintaining a constant pressure in the electrolyte storage space CS. For this purpose, in the gas sensor 1 of this embodiment, two reaction electrode external electrodes 51, 511, a counter electrode external electrode 52, and a reference electrode external electrode 53 are arranged so that an outlet-side permeable sheet OS having two extensions OS2, OS2 extending substantially in the same straight line in opposite directions can be provided.

[0080] As described above, the second reaction electrode 311 is positioned in the second electrode structure support space SS1 on the electrode structure support portion 212 of the case body 21 so as to straddle the edge of the extension groove portion 2121b in a direction perpendicular to the extension direction of the extension groove portion 2121b (see Figure 14). Therefore, a part of the second reaction electrode 311 is provided on the case body 21 via the electrolyte supply electrolyte holding member 37 (extension portion 37b), and the other part of the second reaction electrode 311 is provided on the case body 21 without going through the electrolyte supply electrolyte holding member 37 (extension portion 37b). As a result, the second reaction electrode 311 is more reliably supplied with electrolyte 6 from the electrolyte supply electrolyte holding member 37, and is pressed by the hard case body 21 without going through the electrolyte supply electrolyte holding member 37, thereby more reliably ensuring contact with the second reaction electrode lead wire 411. For this purpose, it is preferable that the second reaction electrode lead wire 411 is arranged to be connected to another part of the second reaction electrode 311 provided on the case body 21 without going through the electrolyte supply electrolyte holding member 37 (extension 37b), as shown in Figure 14.

[0081] As shown in Figure 13, the case cover 22 of case 2 is provided with two capillary members 22c, 22c corresponding to the positions where the two reaction electrodes 31, 311 are each provided. Gas flows into case 2 through gas inlet holes h1 provided in each of the two capillary members 22c, 22c, and the gas is supplied to the two reaction electrodes 31, 311 provided corresponding to each capillary member 22c. By providing a capillary member 22c for each reaction electrode 31, 311, the size of the gas inlet hole h1 can be changed to obtain suitable gas output characteristics, for example, depending on the type of gas to be detected. However, it is sufficient that the case cover 22 is provided with holes for gas to flow into case 2 corresponding to each of the reaction electrodes 31, 311, and only one capillary member may be provided corresponding to one of the two reaction electrodes 31, 311, or it may not be necessary to provide any capillary members at all.

[0082] The gas sensor 1 of the second embodiment can be manufactured in the same manner as the manufacturing method of the gas sensor 1 described with respect to the gas sensor 1 of the first embodiment.

[0083] <Third Embodiment> In the gas sensor 1 of the third embodiment, as shown in Figures 15 and 16, the electrodes of the electrode structure 3 include three reaction electrodes 31, 311, and 312 for detecting different target gases, one counter electrode 32, and one reference electrode 33. In this embodiment, one counter electrode 32 and one reference electrode 33 are used in common for the three reaction electrodes 31, 311, and 312. However, the electrodes of the electrode structure 3 may include three counter electrodes corresponding to each of the three reaction electrodes 31, 311, and 312. In that case, the three counter electrodes can be formed, for example, by depositing three electrode materials spaced apart from each other on a single breathable sheet, or they can be formed separately from each other. The gas sensor 1 can detect a first target gas, such as oxygen gas, using the first reaction electrode 31 of the three reaction electrodes 31, 311, and 312; detect a second target gas, such as hydrogen sulfide gas, using the second reaction electrode 311 of the three reaction electrodes 31, 311, and 312; and detect a third target gas, such as carbon monoxide gas, using the third reaction electrode 312 of the three reaction electrodes 31, 311, and 312. The electrodes of the electrode structure 3 may include two counter electrodes for the three reaction electrodes 31, 311, and 312. The two counter electrodes can be used interchangeably depending on the reaction occurring on them. For example, one of the two counter electrodes can be used as a reaction electrode to detect a target gas that undergoes an oxidation reaction (e.g., oxygen gas), and the other can be used as a reaction electrode to detect a target gas that undergoes a reduction reaction (e.g., hydrogen sulfide gas, carbon monoxide gas). In this case, the two counter electrodes can be formed, as described above, by depositing two electrode materials (e.g., approximately semicircular) on a single permeable sheet (e.g., approximately circular) with a slit-like gap between them, or they can be formed separately. Similarly, even when there are more than three reaction electrodes, the two counter electrodes can be used interchangeably depending on the oxidation and reduction reactions occurring on them.

[0084] The first to third reaction electrodes 31, 311, and 312 are arranged so as not to overlap with each other when viewed in the height direction H, as shown in Figure 15. More specifically, the first reaction electrode 31 is stacked with the counter electrode 32 and the reference electrode 33 in the height direction H, while the second and third reaction electrodes 311 and 312 are positioned spaced apart from the first reaction electrode 31, the counter electrode 32, and the reference electrode 33 in a direction perpendicular to the height direction H (horizontal direction). The second and third reaction electrodes 311 and 312 are positioned spaced apart from each other in a direction perpendicular to the height direction H (horizontal direction). This allows for an independent external gas supply to each of the reaction electrodes 31, 311, and 312. The positions of the three reaction electrodes 31, 311, and 312 in the height direction H relative to each other are not particularly limited, but in this embodiment, the first to third reaction electrodes 31, 311, and 312 are fixed to the upper wall of the case cover 22, so that the second and third reaction electrodes 311 and 312 are positioned at a height corresponding to the first reaction electrode 31. In this embodiment, the first to third reaction electrodes 31, 311, and 312 have the same configuration as the reaction electrode 31 described with respect to the gas sensor 1 of the first embodiment, and have the same configuration as each other, but they may have a different configuration from the reaction electrode 31 of the first embodiment, or they may have different configurations from each other.

[0085] In the electrode structure 3, which includes three reaction electrodes 31, 311, and 312, the electrolyte holding member 34 for the reaction electrodes, which is stacked on the three reaction electrodes 31, 311, and 312, is formed in a shape and size that contacts all surfaces of the three reaction electrodes 31, 311, and 312, as shown in Figure 15. This allows one electrolyte holding member 34 to supply electrolyte 6 to all three reaction electrodes 31, 311, and 312. In this embodiment, the electrolyte holding member 34 for the reaction electrodes is formed in a sheet shape and size that fits the first electrode structure support space SS, the second electrode structure support space SS1, and the third electrode structure holding space SS2 of the case body 21, which will be described later. Similarly, the electrolyte holding member 36 for the reference electrode is also formed in a sheet shape with substantially the same shape and size as the electrolyte holding member 34 for the reaction electrodes. In this embodiment, the counter electrode electrolyte holding member 35 is formed in the shape of a substantially circular sheet that fits into the first electrode structure support space SS, but it may also be formed in the shape of a sheet with substantially the same shape and size as the reaction electrode electrolyte holding member 34. Furthermore, the support sheets 38 and 39, which are optionally stacked within the electrode structure 3, have substantially the same shape as the reaction electrode electrolyte holding member 34 and the reference electrode electrolyte holding member 36, but are formed to be smaller in size than the reaction electrode electrolyte holding member 34 and the reference electrode electrolyte holding member 36 so as not to hinder contact between the electrolyte holding members.

[0086] The electrolyte supply and holding member 37, which is laminated within the electrode structure 3, comprises a sheet-like main body portion 37a and two sheet-like extension portions 37b, 37b that project from the main body portion 37a out of plane and in opposite directions on substantially the same straight line, as shown in Figure 15. The main body portion 37a is formed to fit into the first electrode structure support space SS on the electrode structure support portion 212, which will be described later, and also to fit into the main body groove portion 2121a (see Figure 16) of the electrode structure support portion 212, which will be described later. The main body portion 37a is laminated in the first electrode structure support space SS with the first reaction electrode 31, counter electrode 32, and reference electrode 33 (and the electrolyte holding members for each electrode). In addition, each of the two extension portions 37b, 37b is formed to fit into the extension groove portion 2121b (see Figure 16) of the electrode structure support portion 212, which will be described later. The two extensions 37b, 37b extend in opposite directions relative to the electrode structure support portion 212 of the case body 21, are bent at the outer edge of the electrode structure support portion 212, and are positioned opposite each other within the electrolyte containment space CS (see also Figure 2). Parts of each of the two extensions 37b, 37b are partially laminated with the second and third reaction electrodes 311, 312 (as well as the electrolyte holding member 34 for the reaction electrode and the electrolyte holding member 36 for the reference electrode) in the second and third electrode structure support spaces SS1, SS2, respectively.

[0087] The gas sensor 1 of this embodiment includes, corresponding to the presence of three reaction electrodes 31, 311, and 312, three reaction electrode lead wires 41, 411, and 412 connected to each of the three reaction electrodes 31, 311, and 312, as shown in Figures 15 and 16, and three reaction electrode external electrodes 51, 511, and 512 connected to each of the three reaction electrode lead wires 41, 411, and 412. In other words, in the gas sensor 1 of this embodiment, the lead wire 4 includes the three reaction electrode lead wires 41, 411, and 412, a counter electrode lead wire 42 connected to the counter electrode 32, and a reference electrode lead wire 43 connected to the reference electrode 33. The external electrode 5 includes three reaction electrode external electrodes 51, 511, and 512, a counter electrode external electrode 52 connected to the counter electrode lead wire 42, and a reference electrode external electrode 53 connected to the reference electrode lead wire 43. The three external electrodes 51, 511, and 512 for the reaction electrodes are positioned such that the connection points CP of the three external electrodes 51, 511, and 513 are located at the height corresponding to the three reaction electrodes 31, 311, and 312. This allows all three reaction electrode lead wires 41, 411, and 412 to be routed along a nearly horizontal direction when connecting the three reaction electrodes 31, 311, and 312 to the three external electrodes 51, 511, and 512 with the three reaction electrode lead wires 41, 411, and 412, respectively, without the need for significant bending. As a result, the three reaction electrode lead wires 41, 411, and 412 can be routed easily, and the gas sensor 1 can be manufactured easily.

[0088] In the gas sensor 1 of this embodiment, case 2 has a different configuration from case 2 of the gas sensor 1 of the first embodiment in order to accommodate additional second and third reaction electrodes 311, 312, lead wires 411, 412 for the second and third reaction electrodes, and external electrodes 511, 512 for the second and third reaction electrodes compared to the gas sensor 1 of the first embodiment. The case body 21 of case 2 in this embodiment includes one external electrode support section 214 for supporting three external electrodes (in this embodiment, the external electrode 51 for the first reaction electrode, the external electrode 52 for the counter electrode, and the external electrode 53 for the reference electrode) and one external electrode support section 214 for supporting two external electrodes (in this embodiment, the external electrodes 511, 512 for the second and third reaction electrodes). The external electrode support section 214 for supporting the three external electrodes 51, 52, and 53 is provided with three guide sections 7 and one holding structure section 8, and the external electrode support section 214 for supporting the two external electrodes 511 and 512 is provided with two guide sections 7 and one holding structure section 8. Regardless of the illustrated example, the guide sections 7 may have the same structure as the guide section 7 of the gas sensor 1 of the first embodiment. The number, shape, and arrangement of the external electrode support section, guide sections, and holding structure section can be appropriately modified according to the number, shape, and arrangement of the reaction electrode, counter electrode, reference electrode, and external electrodes.

[0089] In this embodiment, as shown in Figures 15 and 16, the case body 21 has a first electrode structure support space SS formed on the surface of the electrode structure support portion 212, surrounded by two external electrode support portions 214, 214 near the horizontal center of the electrode structure support portion 212, and a second electrode structure support space SS1 and a third electrode structure support space SS2 formed between two adjacent external electrode support portions 214, 214 along the periphery of the first electrode structure support space SS. In the first electrode structure support space SS, the first reaction electrode 31, counter electrode 32, and reference electrode 33 (and electrolyte holding members for each electrode) are supported; in the second electrode structure support space SS1, the second reaction electrode 311 (and electrolyte holding member 34 for the reaction electrode and electrolyte holding member 36 for the reference electrode) are supported; and in the third electrode structure support space SS2, the third reaction electrode 312 (and electrolyte holding member 34 for the reaction electrode and electrolyte holding member 36 for the reference electrode) are supported. In this embodiment, the first electrode structure support space SS is formed to have the same shape and size as the electrode structure support space SS described for the gas sensor 1 of the first embodiment, but it may be formed to have a different shape and size than the electrode structure support space SS of the first embodiment.

[0090] As shown in Figure 16, the electrode structure support portion 212 of the case body 21 has a groove portion 2121 into which the outflow side breathable sheet OS and the electrolyte supply electrolyte holding member 37 are arranged. The groove portion 2121 is formed in a shape and size that allows the outflow side breathable sheet OS and the electrolyte supply electrolyte holding member 37 to be inserted. The groove portion 2121 includes a main groove portion 2121a into which the main body portion OS1 of the outflow side breathable sheet OS and the main body portion 37a of the electrolyte supply electrolyte holding member 37 can be inserted, and two extension groove portions 2121b, 2121b into which the extension portion OS2 of the outflow side breathable sheet OS and the extension portion 37b of the electrolyte supply electrolyte holding member 37 can be inserted. The main groove 2121a is located below the first electrode structure support space SS, and the two extension grooves 2121b, 2121b are located in the lower parts of the second and third electrode structure support spaces SS1, SS2, respectively. The second and third reaction electrodes 311, 312, supported in the second and third electrode structure support spaces SS1, SS2, are each positioned to straddle the edge of the extension groove 2121b in a direction perpendicular to the extension direction of the extension groove 2121b.

[0091] The outlet-side permeable sheet OS, positioned in the groove 2121 of the electrode structure support portion 212, comprises a sheet-like main body OS1 and two sheet-like extensions OS2, OS2 projecting from the main body OS1 out of plane in opposite directions on a substantially straight line, as shown in Figure 15. The two extensions OS2, OS2 extend in opposite directions relative to the electrode structure support portion 212 of the case body 21 along the extension groove 2121b of the groove 2121, and are bent at the outer edge of the electrode structure support portion 212 to be positioned opposite each other within the electrolyte containment space CS (see also Figure 2). For example, if the gas sensor 1 is tilted toward one of the two extensions OS2, OS2, the entirety of one extension OS2 within the electrolyte containment space CS becomes immersed in the electrolyte 6, making it difficult for the gas in the electrolyte containment space CS to be discharged to the outside of the case 2 through the extension OS2. However, even if that were to happen, since the other of the two extensions OS2 is not immersed in the electrolyte 6 at least partially (near the boundary between the electrode structure support 212 and the electrolyte containment space CS), the gas in the electrolyte containment space CS can be discharged to the outside of the case 2 through the other extension OS2. In the gas sensor 1 of this embodiment, by providing an outlet-side permeable sheet OS having two extensions OS2, OS2 extending substantially in the same straight line in opposite directions, even if the gas sensor 1 is tilted, the gas in the electrolyte containment space CS can be discharged to the outside of the case 2, thereby maintaining a constant pressure in the electrolyte containment space CS. For this purpose, in the gas sensor 1 of this embodiment, three reaction electrode external electrodes 51, 511, 512, a counter electrode external electrode 52, and a reference electrode external electrode 53 are arranged so that an outlet-side permeable sheet OS having two extensions OS2, OS2 extending substantially in the same straight line in opposite directions can be provided.

[0092] As described above, the second and third reaction electrodes 311 and 312 are positioned in the second and third electrode structure support spaces SS1 and SS2 on the electrode structure support portion 212 of the case body 21, respectively, so as to straddle the edge of the extension groove portion 2121b in a direction perpendicular to the extension direction of the extension groove portion 2121b (see Figure 16). Therefore, a portion of each of the second and third reaction electrodes 311 and 312 is provided on the case body 21 via the electrolyte supply electrolyte holding member 37 (extension portion 37b), and the other portion of each of the second and third reaction electrodes 311 and 312 is provided on the case body 21 without the electrolyte supply electrolyte holding member 37 (extension portion 37b). As a result, the second and third reaction electrodes 311 and 312 are more reliably supplied with electrolyte 6 from the electrolyte supply electrolyte holding member 37 and are pressed by the rigid case body 21 without going through the electrolyte supply electrolyte holding member 37, thereby more reliably ensuring contact with the second and third reaction electrode lead wires 411 and 412. For this purpose, it is preferable that each of the second and third reaction electrode lead wires 411 and 412 is arranged to be connected to other parts of the second and third reaction electrodes 311 and 312, respectively, which are provided on the case body 21 without going through the electrolyte supply electrolyte holding member 37 (or its extension 37b), as shown in Figure 16.

[0093] As shown in Figure 15, the case cover 22 of case 2 is provided with three capillary members 22c corresponding to the positions where the three reaction electrodes 31, 311, and 312 are located. Gas flows into case 2 from the gas inlet holes h1 provided in each of the three capillary members 22c and is supplied to the three reaction electrodes 31, 311, and 312 provided in relation to each capillary member 22c. By providing a capillary member 22c for each reaction electrode 31, 311, and 312, the size of the gas inlet hole h1 can be changed to obtain suitable gas output characteristics, for example, depending on the type of gas to be detected. However, the case cover 22 only needs to have holes for gas to flow into the case 2 corresponding to each of the reaction electrodes 31, 311, and 312, and the capillary member may be provided as one corresponding to any one of the three reaction electrodes 31, 311, and 312, or as two corresponding to any two, or not necessarily provided at all.

[0094] The gas sensor 1 of the third embodiment can be manufactured in the same manner as the manufacturing method of the gas sensor 1 described with respect to the gas sensor 1 of the first embodiment.

[0095] The above describes some embodiments of the constant potential electrolytic gas sensor and a method for manufacturing the constant potential electrolytic gas sensor. However, the constant potential electrolytic gas sensor and the method for manufacturing the constant potential electrolytic gas sensor of the present invention are not limited to the embodiments described above. The embodiments described above mainly describe an invention having the following configuration.

[0096] (1) A case comprising the case body, An electrode structure including at least two electrodes provided on the case body, At least two lead wires extending along each of the surfaces of the at least two electrodes and connected to each of the surfaces of the at least two electrodes, Extending from the outside of the case into the inside of the case, provided on the case body, and connected to each of the at least two lead wires, at least two external electrodes A constant potential electrolytic gas sensor comprising: The at least two external electrodes are arranged such that the connection points of the external electrodes to which the lead wires are connected are located at a height corresponding to the electrode structure. The case body has a holding structure that can hold a predetermined amount of protective agent so as to cover the connection point for each of the at least two external electrodes. Constant potential electrolytic gas sensor.

[0097] (2) The at least two external electrodes are arranged such that the heights of the connection points of the at least two external electrodes are substantially the same as each other. (1) The constant potential electrolytic gas sensor described above.

[0098] (3) The holding structure includes a wall formed around the horizontal connection point of the external electrode, (1) or (2) the constant potential electrolytic gas sensor.

[0099] (4) The holding structure includes a guide portion that guides the lead wire along an introduction path from outside the case body through the connection point of the external electrode toward the electrode structure, A constant potential electrolytic gas sensor as described in any one of (1) to (3).

[0100] (5) The guide section A first guide portion that guides the lead wire from the outside of the case body toward the connection point of the external electrode, A second guide portion that guides the lead wire from the connection point of the external electrode toward the electrode structure, Equipped with, (4) The constant potential electrolytic gas sensor described above.

[0101] (6) The holding structure includes a wall formed around the horizontal connection point of the external electrode, The first guide portion is formed by the peripheral wall of a first recess provided on the wall portion opposite to the electrode structure in the introduction path, The second guide portion is formed by the peripheral wall of a second recess provided on the wall portion on the side of the electrode structure in the introduction path. (5) The constant potential electrolytic gas sensor described above.

[0102] (7) The at least two electrodes include at least two reaction electrodes for detecting different target gases, a counter electrode, and a reference electrode, The at least two lead wires include at least two reaction electrode lead wires connected to each of the at least two reaction electrodes, a counter electrode lead wire connected to the counter electrode, and a reference electrode lead wire connected to the reference electrode. The at least two external electrodes include at least two reaction electrode external electrodes connected to each of the at least two reaction electrode lead wires, a counter electrode external electrode connected to the counter electrode lead wire, and a reference electrode external electrode connected to the reference electrode lead wire. The first of the at least two reaction electrodes is stacked in the height direction with the counter electrode and the reference electrode. The other reaction electrode among the at least two reaction electrodes is positioned at a height corresponding to the first reaction electrode, the counter electrode and the reference electrode, at a position spaced apart from the first reaction electrode, the counter electrode and the reference electrode in a direction perpendicular to the height direction. A constant potential electrolytic gas sensor as described in any one of (1) to (6).

[0103] (8) The at least two external electrodes for the reaction electrodes are arranged such that the connection points of the at least two external electrodes for the reaction electrodes are located at a height corresponding to the at least two reaction electrodes. (7) The constant potential electrolytic gas sensor described above.

[0104] (9) A method for manufacturing a constant potential electrolytic gas sensor, The aforementioned constant potential electrolytic gas sensor, A case that includes the case body, An electrode structure including at least two electrodes provided on the case body, At least two lead wires extending along each of the surfaces of the at least two electrodes and connected to each of the surfaces of the at least two electrodes, Extending from the outside of the case into the inside of the case, provided on the case body, and connected to each of the at least two lead wires, at least two external electrodes Equipped with, The at least two external electrodes are arranged such that the connection points of the external electrodes to which the lead wires are connected are located at a height corresponding to the electrode structure. The case body has a holding structure that can hold a predetermined amount of protective agent so as to cover the connection point for each of the at least two external electrodes. The method described above is A step of placing the lead wire between the surface of the electrode and the connection point of the external electrode, With the lead wire positioned on the surface of the electrode, the step of connecting the lead wire to the external electrode at the connection point of the external electrode, A step of supplying a predetermined amount of protective agent to the holding structure so as to cover the connection point of the external electrode with the protective agent. including, method. [Explanation of Symbols]

[0105] 1. Constant potential electrolytic gas sensor (gas sensor) 2 cases 21 Case body 211 Base 212 Electrode structure support part 212r recess 2121 Groove 2121a Main body groove 2121b Extension groove 213 Intermediate support part 214 External electrode support part 214a Lower external electrode support part 214b Upper external electrode support part 22 Case Covers 22c Capillary component 22p protrusion 22r recess 3 Electrode structure 31 Reacting electrode (first reacting electrode) 31a Catalyst layer 31b Breathable sheet 311 Second reaction electrode 312 Third reaction electrode 32 Opposite Poles 33 Reference pole 34 Electrolyte holding member for reaction electrode 35 Counter electrode electrolyte holding member 36 Electrolyte holding member for reference electrode 37 Electrolyte supply and electrolyte holding member 37a Main body 37b Extension 38, 39 Support sheet 4 Lead wires 41 Reactor lead wire (First reaction electrode lead wire) 411 Lead wire for the second reaction electrode 412 Lead wire for the third reaction electrode 42. Lead wire for the opposite electrode 43 Reference pole lead wire 5 External electrode 51 External electrode for reaction electrode (First external electrode for reaction electrode) 511 External electrode for the second reaction electrode 512 External electrode for the third reaction electrode 52 External electrode for counter electrode 53 External electrode for reference electrode 6 Electrolyte 7 Information Department 71 First Information Desk 72 Second Information Desk 8 Retaining structure B Bottom CP connection location CS Electrolyte Storage Space H (height direction) h1 Gas inlet h2 gas outlet IB inflow buffer membrane OB Outflow Buffer Membrane OS Outlet side breathable sheet OS1 Main Unit OS2 extension PA Protective Agent S interior space SS electrode structure support space (first electrode structure support space) SS1 Second electrode structure support space SS2 Third electrode structure support space W wall W1 Partition wall WR1 First recess WR2 Second recess

Claims

1. A case that includes the case body, An electrode structure including at least two electrodes provided on the case body, At least two lead wires extending along the surface of each of the at least two electrodes and connected to the surface of each of the at least two electrodes, Extending from the outside of the case into the inside of the case, provided on the case body, and connected to each of the at least two lead wires, at least two external electrodes A constant potential electrolytic gas sensor comprising, The at least two external electrodes are arranged such that the connection points of the external electrodes to which the lead wires are connected are located at a height corresponding to the electrode structure. The case body has a holding structure that can hold a predetermined amount of protective agent so as to cover the connection point for each of the at least two external electrodes. The holding structure includes a guide portion that guides the lead wire along an introduction path from outside the case body through the connection point of the external electrode toward the electrode structure. Constant potential electrolytic gas sensor.

2. The at least two external electrodes are arranged such that the heights of the connection points of the at least two external electrodes are substantially the same as each other. The constant potential electrolytic gas sensor according to claim 1.

3. The holding structure includes a wall formed around the horizontal connection point of the external electrode. The constant potential electrolytic gas sensor according to claim 1 or 2.

4. (delete)

5. The aforementioned guide section A first guide portion that guides the lead wire from the outside of the case body toward the connection point of the external electrode, A second guide portion that guides the lead wire from the connection point of the external electrode toward the electrode structure, Equipped with, The constant potential electrolytic gas sensor according to claim 1 or 2.

6. The holding structure includes a wall formed around the horizontal connection point of the external electrode, The first guide portion is formed by the peripheral wall of a first recess provided in the wall portion on the side of the introduction path opposite to the electrode structure, The second guide portion is formed by the peripheral wall of a second recess provided on the wall portion on the side of the electrode structure in the introduction path. The constant potential electrolytic gas sensor according to claim 5.

7. The at least two electrodes include at least two reaction electrodes, a counter electrode, and a reference electrode for detecting different target gases. The at least two lead wires include at least two reaction electrode lead wires connected to each of the at least two reaction electrodes, a counter electrode lead wire connected to the counter electrode, and a reference electrode lead wire connected to the reference electrode. The at least two external electrodes include at least two reaction electrode external electrodes connected to each of the at least two reaction electrode lead wires, a counter electrode external electrode connected to the counter electrode lead wire, and a reference electrode external electrode connected to the reference electrode lead wire. The first of the at least two reaction electrodes is stacked in the height direction with the counter electrode and the reference electrode. The other reaction electrode among the at least two reaction electrodes is positioned at a height corresponding to the first reaction electrode, the counter electrode and the reference electrode, at a position spaced apart from the first reaction electrode, the counter electrode and the reference electrode in a direction perpendicular to the height direction. The constant potential electrolytic gas sensor according to claim 1 or 2.

8. The at least two external electrodes for the reaction electrodes are arranged such that the connection points of the at least two external electrodes for the reaction electrodes are located at a height corresponding to the at least two reaction electrodes. The constant potential electrolytic gas sensor according to claim 7.

9. A method for manufacturing a constant potential electrolytic gas sensor, The aforementioned constant potential electrolytic gas sensor, A case that includes the case body, An electrode structure including at least two electrodes provided on the case body, At least two lead wires extending along the surface of each of the at least two electrodes and connected to the surface of each of the at least two electrodes, Extending from the outside of the case into the inside of the case, provided on the case body, and connected to each of the at least two lead wires, at least two external electrodes Equipped with, The at least two external electrodes are arranged such that the connection points of the external electrodes to which the lead wires are connected are located at a height corresponding to the electrode structure. The case body has a holding structure that can hold a predetermined amount of protective agent so as to cover the connection point for each of the at least two external electrodes. The holding structure includes a guide portion that guides the lead wire along an introduction path from outside the case body through the connection point of the external electrode toward the electrode structure, The method described above is A step of placing the lead wire between the surface of the electrode and the connection point of the external electrode, With the lead wire positioned on the surface of the electrode, the step of connecting the lead wire to the external electrode at the connection point of the external electrode, A step of supplying a predetermined amount of protective agent to the holding structure so as to cover the connection point of the external electrode with the protective agent. including, method.

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