JP2004219164A - Constant potential electrolytic type gas sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a samll-sized constant potential electrolytic type gas sensor which develops an expected pressure adjusting function certainly, sets a plurality of gas detecting electrodes to a mutually sufficient liquidtight state, prevents the leakage of an electrolyte certainly to perform the highly reliable detection of gas. <P>SOLUTION: This constant potential electrolytic type gas sensor is equipped with a casing constituted so that an undersurface side casing member having a gas permeating port is provided on one end side of a cylindrical casing main body while an upper surface side casing member is provided on the other end side of the main body and the gas permeating port is sealed by a gas permeable hydrophobic diaphragm to form an electrolyte chamber. An acting electrode is arranged in the casing in opposed relation to the diaphragm and a counter electrode is arranged in the casing so as to be made liquidtight with respect to the acting electrode. Further, a communication hole letting the electrolyte chamber communicate with the open air is formed to the outer peripheral surface of the upper surface side casing member through the recessed place formed to the inner surface of the casing member and a gas permeable hydrophobic pressure adjusting membrane is arranged on the inner surface of the casing member so as to close the recessed place. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a potentiostatic gas sensor, and more particularly, to a potentiostatic gas sensor having a gas-permeable hydrophobic diaphragm and a working electrode separated from each other.
[0002]
[Prior art]
At present, for example, when detecting a toxic gas in a semiconductor manufacturing plant or the like, the reason is that the gas concentration can be detected with high selectivity of the target detection target gas, high sensitivity, and high accuracy. A potentiostatic gas sensor utilizing an electrolytic reaction is widely used.
[0003]
Many such constant potential electrolytic gas sensors have been proposed. For example, Patent Literature 1 has openings at both ends, and these openings are sealed with a hydrophobic porous membrane to form an electrolytic solution chamber. The sensor body (casing) in which the electrodes are provided on the liquid contact side surfaces of the respective diaphragms and the electrolyte is accommodated in the sensor body is described. .
[0004]
Thus, in the potentiostatic gas sensor, for example, from the viewpoint of preventing a decrease in sensitivity due to a change in pressure in the electrolyte chamber, means for adjusting the pressure in the electrolyte chamber to be in an equilibrium state with the outside atmosphere is taken. In the galvanostatic gas sensor having the above configuration, the internal space of the electrolytic solution chamber is opened to the outside atmosphere through the non-electrode forming portion of the diaphragm, thereby ensuring a liquid-tight state. The pressure in the electrolytic solution chamber is in equilibrium with the external atmospheric pressure, and a decrease in sensitivity due to a pressure change in the electrolytic solution chamber is compensated.
[0005]
[Patent Document 1]
JP-A-5-223777
[Problems to be solved by the invention]
As described above, in the galvanostatic gas sensor, for example, from the viewpoint of preventing a decrease in sensitivity due to a pressure change in the electrolytic solution chamber, the sensitivity is reduced by adjusting the pressure in the electrolytic solution to be in an equilibrium state with the outside atmosphere, for example. It is common practice to take measures to compensate for this.
Thus, the present invention provides a small, constant-potential-electrolysis-type gas sensor having a novel structure capable of reliably exerting a desired pressure regulation function in an electrolytic chamber and performing highly reliable gas detection. The purpose is to:
[0007]
Another object of the present invention is to make it possible for a plurality of required gas detection electrodes to be in a sufficiently liquid-tight state with each other and to reliably prevent leakage of the electrolyte, and An object of the present invention is to provide a small-sized constant potential electrolytic gas sensor having a novel structure capable of performing highly sensitive gas detection.
[0008]
[Means for Solving the Problems]
The constant potential electrolytic gas sensor of the present invention is provided with a lower casing member having a gas transmission port formed at one end opening of a cylindrical casing body and an upper casing member provided at the other end opening. A casing in which a gas permeable opening in the lower surface side casing member is sealed by a gas permeable hydrophobic diaphragm to form an electrolytic solution chamber, in which at least two gas detection electrodes, a working electrode and a counter electrode, are operated. The electrode is disposed so as to be in contact with the surface on the liquid contact side of the gas-permeable hydrophobic diaphragm, and the counter electrode is disposed and provided in a liquid-tight state with respect to the working electrode, and is provided.
The upper casing member constituting the casing has a recess formed on the inner surface exposed to the internal space of the electrolyte chamber, and a communication hole for communicating the electrolyte chamber with the outside atmosphere via the recess is formed on the upper side. It is formed so as to open to the outer surface of the casing member, and is characterized in that a pressure adjusting film having gas permeability is provided on the inner surface of the upper casing member so as to close the recess.
[0009]
In the galvanostatic gas sensor of the present invention, the working electrode and the counter electrode both have a plate-like electrode body in which a fluid flow passage is formed, and both the working electrode and the counter electrode are connected to the working electrode. Electrolyte is impregnated with an electrolyte between the electrode body and the electrode body related to the counter electrode, and is stacked and stacked in a state sandwiched by an electrolyte holding member, and is configured as one electrode structure.
In a state where the gas permeation port faces in a direction other than the upward direction, so that the electrolytic solution accommodated in the electrolytic solution chamber is impregnated into the electrolytic solution holding member through the fluid flow passage formed in each of the working electrode and the counter electrode. It is preferably used.
[0010]
In the potentiostatic gas sensor of the present invention, each of the working electrode and the counter electrode is constituted by a plate-shaped electrode body and a protruding terminal piece for connecting the electrode body to an external lead member. It is preferable that each of the protruding terminal pieces of the working electrode and the counter electrode is led out of the casing at a position where they are arranged in the circumferential direction and are separated from each other.
[0011]
In the galvanostatic gas sensor having such a configuration, the working electrode and the counter electrode each have an electrode body portion forming an electrode body and a protruding direction in which the base end portion is different from each other when the electrode body portions are stacked. And an electrode forming material having a protruding terminal piece portion extending in parallel with the distal end portion is bent so that the base end portion of the protruding terminal piece portion extends in the lamination direction of the electrode body, and the tip of the protruding terminal piece portion is bent. This is achieved by using a structure in which a side portion is bent so as to extend in the surface direction of the electrode body, and a portion projecting from the outer surface of the casing is bent so as to extend in the stacking direction of the electrode body.
[0012]
[Action]
According to the constant potential electrolytic gas sensor having the above-described configuration, a recess is formed in the inner surface of the upper casing member constituting the casing, and the internal space in the electrolyte chamber communicates with the outside atmosphere through the recess. A hole is formed, and the gas permeable hydrophobic pressure adjusting film is disposed and provided on the inner surface of the upper casing member so as to close the recess, so that a holding portion is formed in the recess. With the configuration that holds the pressure adjusting film, the problem that the electrolyte may adhere to the holding portion and lower the pressure adjusting function does not occur, and therefore, the intended pressure adjusting function is reliably exhibited. You.
In addition, the internal space of the electrolyte chamber is configured so as to be indirectly opened to the outside atmosphere by a communication hole that opens to the outer surface of the upper casing member through the recess, so that the pressure in the electrolyte chamber is reduced. Excessive pressure difference from atmospheric pressure is prevented.
[0013]
Also, since at least both the working electrode and the counter electrode are stacked through the electrolyte holding member and configured as one electrode structure, a plurality of required gas detection electrodes are grouped together, The space occupied by the gas detection electrode in the entire gas sensor is reduced, and the gas sensor itself is significantly reduced in size.
Moreover, the gas permeation port is used in a direction other than the upward direction, so that the electrolyte is impregnated into the electrolyte holding member through the fluid flow passage formed in each of the working electrode and the counter electrode, and the working electrode and the working electrode are connected to each other. By having a configuration in which the electrolyte layer is formed between the diaphragm and the diaphragm, even when the electrolyte is reduced to a small amount, the electrolyte can be reliably supplied, so that the working electrode and A sufficient liquid-tight state can be obtained between both electrodes of the counter electrode, so that highly reliable gas detection can be reliably performed.
[0014]
Furthermore, the projecting terminal pieces at the working electrode and the counter electrode are configured to be led out of the casing at positions that are spaced apart from each other in the circumferential direction, thereby ensuring high liquid tightness of the electrolytic solution chamber. Since it can be formed in a state where the electrolyte solution is formed, it is possible to reliably prevent the electrolyte solution from leaking.
In addition, by using the protruding terminal pieces relating to the working electrode and the protruding terminal pieces relating to the counter electrode having a specific form, a liquid-tight lead structure in which each protruding terminal piece relating to each electrode is led out in the same direction is provided. It can be obtained reliably with a simple structure.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the drawings.
FIG. 1 is a longitudinal sectional view schematically showing the configuration of an example of the potentiostatic gas sensor of the present invention, FIG. 2 is a side view of the potentiostatic gas sensor shown in FIG. 1, and FIG. FIG. 4 is an exploded sectional view of the constant potential electrolytic gas sensor shown in FIG. 4, and FIG. 4 is an enlarged sectional view showing the configuration of the electrode structure in the constant potential electrolytic gas sensor shown in FIG. Here, in this specification, the vertical direction in FIG. 1 is referred to as “axial direction”, and the horizontal direction is referred to as “radial direction”.
[0016]
This constant potential electrolytic gas sensor includes a casing 10 composed of a cylindrical casing body 10A, a lower casing member 10B, and an upper casing member 10C, and a plurality of necessary gas detection electrodes, in this embodiment. The electrode structure 30 in which the working electrode 31, the counter electrode 32, and the reference electrode 33 are configured as one unit is provided so as to be fitted to one end side opening of the casing body 10A so that the working electrode 31 is exposed to the outer surface. Further, the electrode structure 30 is fitted to the electrode structure fitting recess 14 formed on the other end surface of the lower surface side casing member 10B in which the gas permeation port 11 is formed, and is brought into contact with the casing body 10A. The upper casing member 10C is provided so as to be fitted into the other end side opening of the casing body 10A. It is.
The electrode structure fitting recess 14 in the lower surface side casing member 10B is formed with a stepped portion 14A in which a sealing member such as an O-ring 18A is disposed, and on the inner surface thereof, for example, polytetrafluorocarbon is formed. A gas permeable hydrophobic diaphragm 20 made of a fluororesin such as ethylene (PTFE) is arranged and sealed integrally so as to close the gas permeable port 11, so that the electrolytic solution chamber S in which the electrolytic solution is stored becomes liquid. It is densely formed.
The gas-permeable hydrophobic diaphragm 20 is in a state of being in contact with the working electrode 31.
[0017]
In the casing 10, each gas detection electrode and a plurality of external lead members 25, 25, 25 corresponding thereto are connected to a joint portion between the casing main body 10 </ b> A and the lower surface side casing member 10 </ b> B on the outer peripheral surface thereof. The output terminal portion forming recesses 12 are formed, and are arranged circumferentially apart from each other so as to extend axially outward (upward in FIG. 1) from the input / output terminal portion forming recesses 12. A plurality of guide grooves 13 for arranging external lead members are formed at the salient positions. In FIGS. 1 and 3, reference numeral 19 denotes a through hole for injecting an electrolytic solution into the electrolytic solution chamber S.
[0018]
The upper casing member 10C has an excessively high pressure regulating function for maintaining the internal space of the electrolytic solution chamber S in equilibrium with the pressure of the external atmosphere.
Specifically, on the inner surface exposed to the internal space of the electrolytic solution chamber S, a first space portion 15A having a constant opening diameter and an axially outward portion (FIG. A concave portion 15 having a second space portion 15B having a smaller opening diameter as going toward the upper portion of the recess 15 is formed, and a tapered inner wall surface forming the second space portion 15B in the concave portion 15 is formed. A communication hole 16 extending radially outward is formed so as to open on the outer peripheral surface of the upper casing member 10C, and is formed of a fluororesin such as polytetrafluoroethylene (PTFE) on the inner surface of the upper casing member 10C. The gas-permeable hydrophobic pressure adjusting film 21 is disposed and integrally welded, whereby the internal space of the electrolyte solution chamber S is released to the outside atmosphere in a state where a liquid-tight state is ensured. That.
[0019]
Each of the working electrode 31, the counter electrode 32, and the reference electrode 33 protrudes radially outward from the disk-shaped electrode bodies 31A, 32A, 33A and the entire periphery of the electrode bodies 31A, 32A, 33A. The protruding terminal pieces 31B, 32B, 33B are formed so as to extend, and each of the electrode bodies 31A, 32A, 33A related to each electrode has a fluid flow path, for example, an opening diameter of 0.5 mm. Small through holes 34 are formed at a constant pitch with a density of, for example, 80 holes / cm ² (see FIGS. 5 to 7).
[0020]
The working electrode 31 has, as shown in FIG. 5, a protruding terminal piece portion 41 extending, for example, linearly outwardly in the radial direction from the periphery of the disk-shaped electrode body 31A. It is formed of a working electrode forming material 40 in which, for example, gold is attached to the surface of a substrate.
Specifically, at the bent portion indicated by the broken line A where the protruding terminal piece portion 41 of the working electrode forming material 40 is located at one end thereof, the base end portion 41A is located on the front side in the direction perpendicular to the paper surface (outside the axial direction). ), And the distal end portion 41B is bent so as to extend in the downward direction (radially outward) in the same figure at the portion to be bent indicated by the dashed line B, and further indicated by the dashed line C. At the bent portion, the contact terminal portion 41C is bent so as to extend inward in the vertical direction (inward in the axial direction) with respect to the paper surface, thereby protruding terminal pieces having a rectangular cross-sectional shape as shown in FIG. A working electrode 31 having 31B is formed.
[0021]
As shown in FIG. 6, when the electrode body 32A is stacked coaxially with the electrode body 31A of the working electrode forming material 40 as shown in FIG. Projecting in a direction different from the projecting direction of the protruding terminal piece portion 41 according to the present invention, in other words, a peripheral edge having a predetermined phase angle difference with respect to the protruding direction of the protruding terminal piece portion 41 related to the working electrode forming material 40. The distal end portion 43B having a contact terminal portion 43C at the distal end thereof protrudes and extends radially outward from the position, and extends in parallel with the projecting direction of the protruding terminal piece portion 41 of the working electrode forming material 40. It is formed of a counter electrode forming material 42 having, for example, silver adhered to the surface of a base material made of, for example, stainless steel and having a protruding terminal piece portion 43 bent in a U-shape.
More specifically, at the bent portion indicated by the broken line A where the protruding terminal piece portion 43 of the counter electrode forming material 42 is located at one end thereof, the base end side portion 43A is positioned on the near side in the direction perpendicular to the plane of the drawing (axially outward). ), And the distal end portion 43B is bent so as to extend downward (radially outward) in the same figure at the bent portion indicated by the broken line B, and further, is bent by the broken line C. At the bent portion, the contact terminal forming portion 43C is bent so as to extend toward the back in the vertical direction (inward in the axial direction) with respect to the plane of the paper, and has the same rectangular shape as that of the working electrode 31 as shown in FIG. The counter electrode 32 having the protruding terminal piece 32B having the cross-sectional shape of is formed.
[0022]
The reference electrode 33 is, for example, in a state where the electrode body 33A is coaxially stacked with the electrode bodies 31A and 32A of the working electrode forming material 40 and the counter electrode forming material 42, as shown in FIG. The shape of the whole bent in a "<" shape, which is substantially symmetrical with the protruding terminal piece portion 43 of the counter electrode forming material 42 with respect to the protruding terminal piece portion 41 of the working electrode forming material 40. It is formed of a reference electrode forming material 44 in which, for example, silver is adhered to a surface of a base material made of, for example, stainless steel having a protruding terminal piece portion 45.
Specifically, at the bent portion indicated by the broken line A located at one end of the protruding terminal piece portion 45 in the reference electrode forming material 44, the proximal end portion 45A is positioned on the near side in the direction perpendicular to the paper surface (outward in the axial direction). ), And the distal end portion 45B is bent so as to extend in the downward direction (radially outward) in the same figure at the bent portion indicated by the broken line B, and further, is bent by the broken line C. At the bending point, the contact terminal portion 45C is bent so as to extend toward the back side (inward in the axial direction) in the direction perpendicular to the paper surface, and the protruding terminal piece 33B having a rectangular cross-sectional shape as shown in FIG. Is formed.
[0023]
As described above, in the potentiostatic gas sensor of the present invention, the working electrode 31, the counter electrode 32, and the reference electrode 33 are configured as one electrode structure 30.
In this embodiment, one end has a large-diameter cylindrical portion 36A fitted into the electrode structure fitting recess 14 of the lower surface side casing member 10B, and the other end has a sealing member such as a ring-shaped packing 18B. Has a small-diameter cylindrical portion 36B fitted into one end side opening of the casing main body 10A in a state in which an electrode body disposing through hole 37 extending in the axial direction is formed, and the small-diameter cylindrical shape is formed. The working electrode 31, the counter electrode 32, and the reference electrode 33 are held by the electrode holder 36 in which the notch 38 for disposing the protruding terminal piece that extends in the axial direction at a position circumferentially separated from the wall surface of the portion 36B is formed. Are configured as one unit.
[0024]
Specifically, as shown in FIG. 4, an electrode body 31 </ b> A related to each of the gas detection electrodes of the working electrode 31, the counter electrode 32, and the reference electrode 33 is provided in the electrode body arrangement through hole 37 in the electrode holder 36. , 32A, 33A are made of, for example, filter paper between the electrode body 31A of the working electrode 31 and the electrode body 32A of the counter electrode 32, and between the electrode body 32A of the counter electrode 32 and the electrode body 33A of the reference electrode 33, respectively. The sheet-like electrolytic solution holding members 35A and 35B are disposed in a state of being stacked in this order in the direction of transmission of the test gas (from below to above in FIG. 4) with the sheet electrolyte members 35A and 35B interposed therebetween. The protruding terminal pieces 31B, 32B, and 33B of each gas detection electrode are inserted along the corresponding protruding terminal piece disposing notches 38, and the protruding terminal piece disposing surface in the large-diameter cylindrical portion 36A. 9 and further, in a state where the electrolytic solution holding member 35C is disposed on the electrode body 33A related to the reference electrode 33, the protective plate 50 has its small-diameter cylindrical portion 51 attached to the electrode body. The large-diameter cylindrical portion 52 is fitted into the through-hole 37 and fits into the protection plate fitting recess 36C formed on the inner surface of the small-diameter cylindrical portion 36B of the electrode holder 36 that is exposed to the internal space of the electrolytic solution chamber S. It is integrally provided in a state of being pressed or closely contacted with the electrolytic solution holding member 35C which is combined and located on the uppermost layer.
[0025]
Then, each of the protruding terminal pieces 31B, 32B, 33B in each gas detection electrode is provided with a through hole 37 for arranging the electrode body in the electrode holder 36 at a position where the base end portions 41A, 43A, 45A are circumferentially separated from each other. It extends axially outward along the inner wall surface, and further has distal end portions 41B, 43B, and 45B extending radially outward along the protruding terminal piece disposing surface 39 of the electrode holder 36, and the input / output terminal portion of the casing 10. The contact terminal portions 41C, 43C, and 45C that are led out so as to be spaced apart from each other in the forming recess 12 in the circumferential direction extend inward in the axial direction along the wall surface of the input / output terminal portion forming recess 12. ing.
[0026]
In the protection plate 50 constituting the electrode structure 30, a through hole 53 having an opening diameter of, for example, about 1 mm, which is a fluid flow passage through which a test gas to be introduced is passed and an electrolyte is introduced, has a density of, for example, It is formed to extend in the axial direction at a rate of 40 / cm ² .
[0027]
Each of the external lead members 25 is formed of a pin lead having a semicircular cross-sectional shape at one end 25A positioned at the input / output terminal portion forming recess 12, and a flat surface at the one end 25A. (In FIG. 1, rightward), they are respectively connected to the distal end portions of the protruding terminal pieces 31B, 32B, 33B related to the corresponding gas detection electrodes.
The recess 12 for forming the input / output terminal portion in the casing 10 is covered with an insulating resin layer 17 for liquid-tight sealing, thereby forming a liquid-tight sealing structure.
[0028]
The electrolytic solution used in the potentiostatic gas sensor of the present invention includes, for example, 0.25 mol of potassium iodide (KI), 0.05 mol of potassium iodate (KIO ₃ ), and 0 mol of potassium hydroxide. An aqueous solution of 0.5 mmol is used as a basic composition, and a hydrogen ion concentration adjusting agent, specifically, for example, potassium hydroxide or potassium carbonate is added thereto to adjust the hydrogen ion concentration so as to be more alkaline than neutral. It is composed.
[0029]
Further, the type of the detection target gas is not particularly limited. For example, hydrogen fluoride gas (HF), hydrogen chloride gas (HCl), chlorine gas (Cl ₂ ), fluorine gas (F ₂ ), iodine gas (I ₂ ), bromine gas (Br ₂ ), ozone gas (O ₃ ), chlorine fluoride gas (ClF ₃ ), and the like.
[0030]
Above, the potentiostatic electrolytic gas sensor of the present invention is used in a state where the gas permeation port 11 is oriented in a direction other than the upward direction, for example, in the lateral direction, whereby the electrolytic solution accommodated in the electrolytic solution chamber S is used. The electrolyte flows into the through hole 53 of the protection plate 50 and is impregnated in the electrolyte holding member 35C interposed between the protection plate 50 and the reference electrode 33. Electrolytic solution holding members 35B and 35A intervening between the electrodes are sequentially impregnated into the through holes 34 of the counter electrode 32 and are impregnated in each of the electrolytic solution holding members 35B and 35A. A liquid layer is formed, whereby a liquid-tight state is obtained between the electrodes.
In this state, for example, a test gas such as air in an environmental atmosphere is introduced through the gas-permeable port 11 through the gas-permeable hydrophobic diaphragm 20, and a certain potential difference is generated between the working electrode 31 and the counter electrode 32. A predetermined voltage is applied to each of the working electrode 31 and the counter electrode 32 via the external lead members 25, 25, 25 with reference to the potential state of the reference electrode 33, and a voltage is generated between the working electrode 31 and the counter electrode 32. By measuring the current value, the concentration of the specific component (detection target gas) in the test gas is detected.
The test gas introduced into the electrolyte chamber S passes through the gas-permeable hydrophobic pressure adjusting film 21 and is discharged from the communication hole 16 to the outside atmosphere through the recess 15, whereby the electrolyte chamber S The gas detection operation is performed in a state where the inside is adjusted to a pressure state balanced with the pressure of the outside atmosphere.
[0031]
Thus, according to the potentiostatic electrolytic gas sensor having the above-described configuration, basically, the working electrode 31, the counter electrode 32, and the reference electrode 33 are stacked via the electrolytic solution holding members 35A and 35B. By being configured as one electrode structure 30, a plurality of necessary gas detection electrodes are put together, so that the space occupied by the gas detection electrodes in the entire gas sensor can be reduced. Therefore, the gas sensor itself can be configured as a significantly reduced size.
As a specific example of the dimensions, the axial length of the casing 10 can be, for example, 30 mm, and the outer diameter can be, for example, 20 mm.
[0032]
Moreover, a recess 15 is formed on the inner surface of the upper casing member 10C constituting the casing 10, and a communication hole 16 is formed through the recess 15 to allow the internal space in the electrolyte solution chamber S to communicate with the outside atmosphere. Since the gas permeable hydrophobic pressure adjusting film 21 is provided on the inner surface of the upper casing member 10C so as to close the recess 15, a holding portion is formed in the recess 15. Therefore, the configuration in which the gas permeable hydrophobic pressure adjusting film 21 is held does not cause a problem that the electrolyte may adhere to the holding portion and lower the pressure adjusting function. The function is reliably exhibited, and highly reliable gas detection can be reliably performed.
Further, the internal space of the electrolyte solution chamber S is indirectly opened to the outside atmosphere by a communication hole 16 opened on the outer surface of the upper casing member 10C via the recess 15, so that the electrolyte solution is formed. Excessive pressure difference between the pressure in the chamber S and the atmospheric pressure is prevented.
[0033]
In addition, each of the protruding terminal pieces 31A, 32A, and 33A related to the working electrode 31, the counter electrode 32, and the reference electrode 33 is led out of the casing 10 at a position where they are spaced from each other in the circumferential direction. By being connected to the external lead members 25, 25, 25, the electrolyte chamber S can be configured in a state where high liquid tightness is ensured, so that leakage of the electrolyte can be reliably prevented. Can be.
Further, since the external lead members 25, 25, 25 corresponding to the working electrode 31, the counter electrode 32, and the reference electrode 33 are arranged close to each other, it is extremely advantageous when forming a current supply structure.
[0034]
In addition, the gas permeation port 11 is used in a state other than the upward direction, and the electrolytic solution is passed through the through hole 53 in the protective plate 50 and the through hole 34 formed in each electrode, and the electrolytic solution holding member 35C, 35B and 35A are impregnated with each other and an electrolyte layer is formed between the working electrode 31 and the gas-permeable hydrophobic membrane 20, so that the electrolyte is reduced to a small amount. However, since the electrolyte can be reliably supplied to each of the electrolyte holding members 35C, 35B, and 35A and the gap between the working electrode 31 and the gas-permeable hydrophobic diaphragm 20, a sufficient liquid-tight state is provided between the electrodes. Can be reliably obtained.
Therefore, for example, even when the gas sensor itself is inclined due to being carried by a person and a difference in posture occurs, a sufficiently liquid-tight state can be obtained between the electrodes, and high reliability can be obtained. Gas detection can be performed reliably.
[0035]
Further, the laminate of the electrode bodies 31A, 32A, 33A and the electrolyte holding members 35A, 35B, 35C of each electrode is held by the electrode holder 36 in a state where the stacked body is pressed or closely contacted by the protective plate 50. Thereby, the electrolyte holding members 35A, 35B, and 35C can be reliably prevented from being deformed due to the swelling caused by the impregnation of the electrolyte, so that a substantially uniform liquid-tight state is provided between the electrodes. Can be obtained, and the intended gas detection can be reliably performed.
[0036]
The embodiments of the present invention have been described above, but the present invention is not limited to the above-described embodiments, and various modifications can be made.
For example, in the galvanostatic gas sensor according to the present invention, the provision of the reference electrode is not an essential component, and the gas detection electrode may be composed of at least the working electrode and the counter electrode.
[0037]
Further, in the potentiostatic electrolytic gas sensor according to the present invention, if the fluid flow passage for each electrode is formed so that the electrolyte is substantially uniformly impregnated in the surface direction of the electrolyte holding member, For example, the size of the opening diameter, the formation density, the formation pattern, and other configurations can be appropriately changed, and, for example, a notch shape may be used.
Furthermore, the counter electrode and the reference electrode are not limited to a configuration in which a through hole is formed over the entire surface of the electrode body, as long as a fluid flow path (liquid conduction path) is ensured. It may be something.
Also, the electrolyte does not need to be filled in the electrolyte chamber, and only the amount required to obtain a sufficient liquid-tight state between the electrodes, taking into account the reduction of the electrolyte due to evaporation or the like, is taken into account. What is necessary is just to be accommodated in the liquid chamber.
[0038]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to the potentiostatic electrolytic gas sensor of this invention, a recess is formed in the inner surface of the upper surface side casing member which comprises a casing, and the communication which communicates the internal space in an electrolyte solution chamber with the external atmosphere through the recess. A hole is formed, and the gas permeable hydrophobic pressure adjusting film is disposed and provided on the inner surface of the upper casing member so as to close the recess, so that a holding portion is formed in the recess. With the configuration that holds the pressure adjusting film, there is no problem that the electrolyte may adhere to the holding portion and lower the pressure adjusting function, and therefore, the desired pressure adjusting function can be reliably obtained. Can be.
In addition, the internal space of the electrolyte chamber is configured so as to be indirectly opened to the outside atmosphere by a communication hole that opens to the outer surface of the upper casing member through the recess, so that the pressure in the electrolyte chamber is reduced. Excessive pressure difference from atmospheric pressure is prevented.
[0039]
Also, since at least both the working electrode and the counter electrode are stacked via the electrolyte holding member to form one electrode structure, a plurality of required electrodes are put together, so that the gas sensor The size of the space occupied by the gas detection electrode in the whole is reduced, and the gas sensor itself is significantly reduced in size. Moreover, the gas permeation port is used in a direction other than the upward direction, so that the electrolyte is impregnated into the electrolyte holding member through the fluid flow passage formed in each of the working electrode and the counter electrode, and the working electrode and the working electrode are connected to each other. Since the electrolyte layer is formed between the diaphragm and the diaphragm, the electrolyte can be reliably supplied even when the amount of the electrolyte is reduced to a small amount. In addition, a sufficient liquid-tight state can be obtained between the two electrodes and the counter electrode, so that highly reliable gas detection can be reliably performed.
[0040]
Furthermore, since the projecting terminal pieces at the working electrode and the counter electrode are configured to be led out of the casing at positions spaced apart in the circumferential direction, high liquid tightness of the electrolyte solution chamber is secured. Since it can be formed in a state in which the electrolyte is bent, it is possible to reliably prevent the electrolyte solution from leaking.
In addition, by using the protruding terminal pieces relating to the working electrode and the protruding terminal pieces relating to the counter electrode having a specific form, a liquid-tight lead structure in which each protruding terminal piece relating to each electrode is led out in the same direction is provided. It can be obtained reliably with a simple structure.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view schematically showing the configuration of an example of a potentiostatic gas sensor of the present invention.
FIG. 2 is a side view of the potentiostatic electrolytic gas sensor shown in FIG.
FIG. 3 is an exploded sectional view of the potentiostatic gas sensor shown in FIG.
FIG. 4 is an enlarged cross-sectional view showing a configuration of an electrode structure in the potentiostatic gas sensor shown in FIG.
FIG. 5 is a plan view showing a configuration of a working electrode forming material.
FIG. 6 is a plan view showing a configuration of a counter electrode forming material.
FIG. 7 is a plan view showing a configuration of a reference electrode forming material.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Casing 10A Casing main body 10B Lower surface side casing member 10C Upper surface side casing member 11 Gas permeation port 12 Depression for forming input / output terminals 13 Guide groove for arranging external lead members 14 Depression for electrode structure fitting 14A Step 15 recess Place 15A First space 15B Second space 16 Communication hole 17 Insulating resin layer 18A O-ring 18B Ring packing 19 Electrolyte injection through hole 20 Gas permeable hydrophobic diaphragm 21 Gas permeable hydrophobic pressure adjusting film 25 External lead Member 25A One end side portion S Electrolyte chamber 30 Electrode structure 31 Working electrode 32 Counter electrode 33 Reference electrode 31A, 32A, 33A Electrode body 31B, 32B, 33B Projecting terminal piece 34 Through hole 35A, 35B, 35C Electrolyte holding member 36 Electrode Holder 36A Large-diameter cylindrical part 36B Small-diameter cylindrical part 36C Protective plate fitting recess 37 Electrode Arrangement through hole 38 Protruding terminal piece disposing notch 39 Projecting terminal piece disposing surface 40 Working electrode forming material 42 Counter electrode forming material 44 Reference electrode forming materials 41, 43, 45 Projecting terminal piece portions 41A, 43A, 45A base End portion 41B, 43B, 45B Tip portion 41C, 43C, 45C Contact terminal portion 50 Protective plate 51 Small-diameter tubular portion 52 Large-diameter tubular portion 53 Through hole

Claims (4)

A lower casing member having a gas permeable port formed at one end opening of the cylindrical casing body is provided, and an upper casing member is provided at the other end opening, and the gas permeable port in the lower casing member is provided with a gas. A casing in which an electrolyte solution chamber is formed by being sealed by the permeable hydrophobic diaphragm; and in this casing, at least two gas detection electrodes, a working electrode and a counter electrode, are arranged such that the working electrode is on the liquid contact side of the gas permeable hydrophobic diaphragm. And the counter electrode is disposed in a liquid-tight state with respect to the working electrode, and is provided.
The upper casing member constituting the casing has a recess formed on the inner surface exposed to the internal space of the electrolyte chamber, and a communication hole for communicating the electrolyte chamber with the outside atmosphere via the recess is formed on the upper side. A constant potential electrolysis, wherein the pressure regulating film is formed so as to open on the outer surface of the casing member, and is provided on the inner surface of the upper casing member so as to close the recess. Type gas sensor. Each of the working electrode and the counter electrode has a plate-shaped electrode body in which a fluid flow passage is formed, and both the working electrode and the counter electrode are between the electrode body related to the working electrode and the electrode body related to the counter electrode. An electrolyte holding member to be impregnated with the electrolyte is interposed and stacked in a state of being sandwiched and configured as one electrode structure,
In a state where the gas permeation port faces in a direction other than the upward direction, so that the electrolytic solution accommodated in the electrolytic solution chamber is impregnated into the electrolytic solution holding member through the fluid flow passage formed in each of the working electrode and the counter electrode. 2. The potentiostatic electrolytic gas sensor according to claim 1, wherein the gas sensor is used. Each of the working electrode and the counter electrode is composed of a plate-like electrode body and a protruding terminal piece for connecting the electrode body to an external lead member. The constant-potential-electrolysis-type gas sensor according to claim 1 or 2, wherein the gas sensor is led to the outside of the casing at positions arranged in a circumferentially spaced relationship with each other. The working electrode and the counter electrode each include an electrode body portion forming an electrode body, and a protruding terminal in which a base end portion extends in different protruding directions and a distal end portion extends in parallel with each other when the electrode body portions are stacked. An electrode forming material having a piece portion is bent so that a base end portion of the protruding terminal piece portion extends in the lamination direction of the electrode body, and is bent so that a tip side portion of the protruding terminal piece portion extends in the surface direction of the electrode body. 4. The potentiostatic electrolytic gas sensor according to claim 3, wherein a portion protruding from an outer surface of the casing is formed by being bent so as to extend in a stacking direction of the electrode body.

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