JP2018063129A - Method for manufacturing solid electrolyte sensor and solid electrolyte sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solid electrolyte sensor in which mixing of gases in two spaces sandwiching a sensor element made of solid electrolyte ceramic is suppressed.SOLUTION: The solid electrolyte sensor 1 comprises a cylindrical holder 52, a bottomed cylindrical sensor element 51 made of solid electrolyte ceramics, and a sealing member 50 in which a cylindrical portion of the sensor element is connected to one end of the holder so that the closed internal space of the bottomed tubular is partitioned from the external space. A joint having a metallic annular member that is plastically deformed is used as a sealing member between male screw portions 11 and 12 and nut members 41 and 42 to be mated with the respective male thread portions. The metallic annular member is a pair of a front ferrule 21 and a back ferrule 31, and a pair of a front ferrule 22 and a back ferrule 32.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for manufacturing a solid electrolyte sensor for measuring a gas concentration using a solid electrolyte ceramic as a sensor element, and a solid electrolyte sensor manufactured by the manufacturing method.

  Various solid electrolyte sensors that measure the gas concentration of hydrogen gas, oxygen gas, carbon dioxide gas, water vapor, etc. in the gas phase or in the liquid phase using solid electrolyte ceramics (ion conductive ceramics) as sensor elements have been proposed. The applicant has also made a plurality of proposals in the past (see, for example, Patent Documents 1 and 2). The solid electrolyte sensor uses the principle of a concentration cell that generates a potential difference due to the difference in concentration of the same ions. When the concentration of the gas to be measured is different in the two spaces between which the solid electrolyte is sandwiched, the solid electrolyte sensor Measure power. If the gas concentration in one space is known, the gas concentration in the other space can be known from the measured electromotive force and the temperature of the sensor element by the Nernst equation.

  Therefore, in the solid electrolyte sensor, the two spaces need to be partitioned by the solid electrolyte. In a conventional solid electrolyte sensor, a sensor element is fixed to one end of a cylindrical support member (holder), and the whole of the holder and the sensor element has a bottomed cylindrical shape, thereby partitioning two spaces.

  However, in addition to this, it is difficult to completely and tightly seal between the sensor element and the holder, and a very small gap tends to remain. If there is even a slight gap between the sensor element and the holder, the gas in the space (reference gas) whose gas concentration is known and the gas in the measurement environment are mixed, and accurate measurement cannot be performed. In particular, when the concentration of the measurement target gas in the measurement environment is high, the influence of the gas mixture on the measurement result is large. In addition, when the gas to be measured is hydrogen, the size of the molecule is small, so even if the size of the void is very small, it easily passes through, and the influence of the gas mixing on the measurement result is large.

JP 2011-174832 A JP-A-8-220063

  Therefore, in view of the above circumstances, the present invention is manufactured by a method for manufacturing a solid electrolyte sensor in which mixing of gases in two spaces sandwiching a sensor element made of solid electrolyte ceramics is suppressed, and manufactured by the manufacturing method. An object is to provide a solid electrolyte sensor.

In order to solve the above problems, a method for manufacturing a solid electrolyte sensor according to the present invention (hereinafter, simply referred to as “manufacturing method”)
“A bottomed bottom in which one end of the holder is closed by the sensor element by connecting one end of the cylindrical holder and the cylindrical portion of the bottomed cylindrical sensor element made of solid electrolyte ceramics with a sealing member A method of manufacturing a solid electrolyte sensor in which a cylindrical internal space and an external space are partitioned,
The sealing member is
A joint main body having a male screw portion protruding in opposite directions, and a hole portion passing through each of the two male screw portions in the axial direction;
Two nut members having female screw holes respectively screwed into the two male screw portions;
Two or two pairs of metal annular members respectively interposed between the two male screw portions and the nut member of the screwing counterpart,
With the holder inserted into the hole of one of the male screw portions, the male screw portion and one of the female screw holes are screwed together and the nut member is tightened, so that one of the annular members is While plastically deforming and closing between the inner peripheral surface of the hole and the holder,
In the state where the cylindrical portion of the sensor element is inserted into the hole portion of the other male screw portion, the nut member is tightened by screwing the male screw portion and the other female screw hole. The annular member is plastically deformed to close the space between the inner peripheral surface of the hole and the sensor element.

  In the manufacturing method of this structure, the one end of a holder is obstruct | occluded with a sensor element, and the shape as a whole is made into a bottomed cylindrical shape. At that time, the cylindrical holder and the cylindrical portion of the sensor element having a bottomed cylindrical shape are connected by a sealing member.

  Here, the sealing member includes a male screw portion through which the hole portion penetrates, a nut member having a female screw hole screwed with the male screw portion, and an annular member interposed between the male screw portion and the nut member. Are considered as one set, and the two sets are pipe joints communicating with each other through the hole portion of the male screw portion. If the holder is inserted into the hole of one male screw part and the cylindrical part of the sensor element is inserted into the hole of the other male screw part, the holder and the sensor element are connected via a pipe joint. Then, when the female screw hole of the nut member is screwed into each male screw part and tightened, the metal annular member interposed between them is pushed by the nut member and the hole of the male screw part It is pushed into the part and plastically deforms.

  A pipe joint that plastically deforms a metal annular member between the male screw and the nut member in this way is called a "break-in" joint, and has been used as a joint for gas and liquid piping. Has been. When the metal annular member is plastically deformed and bites into the pipe to be connected, the joint and the pipe are sealed, and as a result, the pipes are connected in a tightly sealed state. Therefore, with regard to such a “bite-in” joint, the pipe to be connected that is conventionally assumed by those skilled in the art as a common sense is a metal pipe or a resin pipe that allows “bite-in” of a metal annular member. there were. That is, it was an idea of those skilled in the art that the annular member can be “sealed because it bites into the pipe”.

  Contrary to the common knowledge of those skilled in the art, the present manufacturing method uses a sealing member that is a “bite-in” joint to connect a sensor element that is a ceramic material in which a metal annular member cannot “break into”. Is. As will be described in detail later, the metal annular member does not bite into the cylindrical portion of the ceramic sensor element, but is pressed against the outer peripheral surface of the cylindrical portion of the sensor element to be plastically deformed. It spreads along the outer peripheral surface of and adheres closely. Therefore, according to this manufacturing method, since the inner space of the bottomed cylindrical shape whose one end of the holder is closed with the sensor element and the outer space are densely divided, the gas mixture in the two spaces sandwiching the sensor element is performed. Can be effectively deterred.

  The holder may be made of metal or ceramic. If the holder is made of metal, the annular member is plastically deformed and bites into the holder. On the other hand, if the holder is made of ceramics, the annular member is plastically deformed and spreads along the outer peripheral surface of the holder, as in the relationship with the cylindrical portion of the sensor element.

Next, the solid electrolyte sensor according to the present invention is:
“Cylindrical holder,
A bottomed cylindrical sensor element made of solid electrolyte ceramics;
By connecting a cylindrical portion of the sensor element to one end of the holder, a sealing member that divides a bottomed cylindrical internal space in which one end of the holder is closed with the sensor element from an external space, Equipped,
The sealing member is
A joint main body having a male screw portion protruding in opposite directions, and a hole portion passing through each of the two male screw portions in the axial direction;
Two nut members having female screw holes respectively screwed into the two male screw portions;
Two or two pairs of metal annular members respectively interposed between the two male screw portions and the nut member of the screwing counterpart,
One of the annular members has an inner periphery of the hole portion in a state where the holder is inserted into the hole portion of the one male screw portion and the male screw portion and the one female screw hole are screwed together. Plastic deformation between the surface and the holder,
The other annular member has the cylindrical portion of the sensor element inserted into the hole portion of the other male screw portion, and the male screw portion and the other female screw hole are screwed together. It is plastically deformed between the inner peripheral surface of the part and the sensor element ".

  This is the configuration of the solid electrolyte sensor manufactured by the above manufacturing method. Of the two or two pairs of annular members, one annular member is plastically deformed between the hole of the male screw portion and the surface of the holder to fill the gap between them, and the other annular member is male. Since the plastic part is deformed between the hole of the screw part and the surface of the cylindrical part of the sensor element to fill the gap between the two, the inner space of the bottomed cylinder in which one end of the holder is closed with the sensor element and the outside The space is densely partitioned, and mixing of gases in the two spaces sandwiching the sensor element is effectively suppressed.

The solid electrolyte sensor according to the present invention has the above-described configuration,
“The holder is made of ceramics”.

  This configuration is a further novel configuration in that “ceramic materials that the annular member cannot bite” “to each other” are connected by a sealing member that is a “break-in” joint.

The solid electrolyte sensor according to the present invention has the above-described configuration,
“The sealing member is a double ferrule-type joint including two pairs of a front ferrule and a back ferrule as a pair as the annular member”. Hereinafter, the front ferrule and the back ferrule may be collectively referred to as “ferrule”.

  The direction in which the female screw hole of the nut member is screwed and tightened with respect to the male screw portion is referred to as “front”, and the direction in which the nut is screwed back is referred to as “rear”. The peripheral surface, the outer peripheral surface of the front ferrule, the inner peripheral surface on the rear end side of the front ferrule, and the outer peripheral surface of the back ferrule are tapered surfaces whose diameter is increased toward the rear end. Therefore, after inserting the cylindrical holder that is the pipe to be connected and the cylindrical portion of the sensor element into the holes of the two male screw portions, the nut member is attached to the male screw portion via the front ferrule and the back ferrule. Then, the back ferrule is pushed by the nut member, and the front end of the back ferrule moves forward while being deformed so as to slip inward from the tapered surface on the rear end side of the front ferrule. Accordingly, the front ferrule moves forward while being deformed so as to be pushed outward, and is deformed so as to be inward from the tapered surface on the rear end side of the male screw portion.

  When the nut member is sufficiently tightened against the male threaded portion, the outer peripheral surface of the front ferrule is pressed against and closely contacts the inner peripheral surface (tapered surface) on the rear end side of the male threaded portion, and the outer peripheral surface of the back ferrule is The inner surface (tapered surface) of the front ferrule is pressed against and closely contacts. Further, the front end of the front ferrule and the front end of the back ferrule are plastically deformed so as to reduce the diameter. The front ferrule plastically deformed on the sensor element side is in close contact with the surface of the sensor element and fills the gap between the sensor element and the hole of the male screw portion. If the holder is made of metal, the front ferrule plastically deformed on the holder side will bite into the surface of the holder like a wedge, and if the holder is made of ceramic, the plastically deformed front ferrule will spread along the outer peripheral surface of the holder and adhere closely To do. Accordingly, each of the holder and the sensor element is tightly connected to the joint body, and as a result, the bottomed cylindrical inner space in which one end of the holder is closed with the sensor element and the outer space are densely partitioned, Mixing of gas in the two spaces sandwiching the element is suppressed.

  In this configuration, the annular member is composed of a pair of a front ferrule and a back ferrule, and the back ferrule acts so as to spread the front ferrule. Therefore, compared to the case where the annular member is made of one member, the front ferrule is easily plastically deformed and the gap is easily filled.

  As described above, as an effect of the present invention, a method of manufacturing a solid electrolyte sensor in which mixing of gases in two spaces sandwiching a sensor element of solid electrolyte is suppressed, and a solid electrolyte sensor manufactured by the manufacturing method Can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS About the solid electrolyte sensor of 1st embodiment of this invention, (a) The end view cut | disconnected in the center in the vertical direction, (b) The principal part side view. It is a principal part exploded view of the solid electrolyte sensor of FIG. About the principal part of the solid electrolyte sensor of FIG. 1, (a) the end view which cut | disconnected the state before a ferrule in the vertical direction in the center, and (b) the state after a ferrule deform | transformed in the center in the vertical direction. It is the cut end view. (A) It is a figure which shows the change of the electromotive force at the time of using the solid electrolyte sensor of FIG. 1, and changing the hydrogen concentration of measurement gas, (b) The division of two space which pinched | interposed the sensor element is insufficient It is a figure which illustrates the change of the electromotive force at the time of using a solid electrolyte sensor and changing the hydrogen concentration of measurement gas. It is the end elevation cut | disconnected in the center in the vertical direction about the modification of the solid electrolyte sensor of FIG. It is a principal part exploded view of the solid electrolyte sensor of 2nd embodiment of this invention. (A) It is a principal part exploded view of the solid electrolyte sensor of 3rd embodiment of this invention, (b), (c) It is an expanded sectional view of the annular member of 3rd embodiment.

  Hereinafter, a solid electrolyte sensor according to a specific embodiment of the present invention and a manufacturing method thereof will be described with reference to FIGS. Here, the case where this invention is applied to the solid electrolyte sensor which measures the gas concentration in a gaseous phase is illustrated.

  First, the structure of the solid electrolyte sensor 1 which is 1st embodiment is demonstrated using FIG. 1 thru | or FIG. The solid electrolyte sensor 1 includes a cylindrical holder 52, a bottomed cylindrical sensor element 51 made of solid electrolyte ceramics, and one end of the holder 52 by connecting the cylindrical portion 51b of the sensor element 51 to one end of the holder 52. Is provided with a sealing member 50 that divides the bottomed cylindrical internal space closed by the sensor element 51 from the external space. The sealing member 50 is a metal double ferrule-type joint.

  Further, as shown in FIG. 1A, the solid electrolyte sensor 1 includes an outer electrode 61 provided on the surface of the sensor element 51 on the bottomed cylindrical outer space side, and a bottomed cylindrical inner space side. And an inner electrode 62 provided on the surface of the sensor element 51. Furthermore, the solid electrolyte sensor 1 further includes a protective tube 60 that is cylindrical and has a diameter larger than that of the holder 52. The holder 52 is inserted into the protective tube 60 and is fixed to the inside of the protective tube 60 by a fixing material 69. It is fixed to the peripheral surface. Further, a gas introduction pipe 70 for introducing a reference gas or a measurement gas into a bottomed cylindrical internal space is inserted into the holder 52.

  More specifically, as shown in FIG. 2, the sealing member 50 includes a joint body 10 having two male screw portions 11 and 12, and a female screw hole that is screwed into the two male screw portions 11 and 12. Two nut members 41 and 42 having 41n and 42n, and two pairs of metal annular members respectively interposed between the two male screw portions 11 and 12 and the nut members 41 and 42 to be screwed together, , Are provided. The two pairs of annular members include a front ferrule 21 and a back ferrule 31 that form a pair, and another front ferrule 22 and a back ferrule 32 that form a pair.

  Specifically, the joint body 10 has a shape protruding from the base portion 10r in a direction in which the two male screw portions 11 and 12 are opposite to each other. The two male screw portions 11 and 12 are each a cylindrical shape having a male screw formed on the outer peripheral surface, and the hole portions 11h and 12h penetrating each in the axial direction are holes penetrating the base portion 10r. It communicates with the part 10h. Further, the outer shape of the base portion 10r is formed in a shape that meshes with a tool such as a wrench. Here, a case where the outer shape of the base portion 10r is a hexagonal column shape meshing with a hexagon wrench is illustrated.

  Of the two male screw portions 11, 12, the outer diameter of one male screw portion 11 is smaller than the outer diameter of the other male screw portion 12. Of the two nut members 41, 42, one nut member 41 is smaller in diameter than the female screw hole 41n, and a screwed portion 41r having a female screw hole 41n having an inner diameter to be screwed into one male screw portion 11. And a bottom wall portion 41g having a small-diameter hole 41h communicating with the female screw hole 41n. The other nut member 42 has a screwed portion 42r having a female screw hole 42n having an inner diameter to be screwed with the other male screw portion 12, a small diameter smaller than the female screw hole 42n and communicating with the female screw hole 42n. A bottom wall portion 42g having a hole 42h. The outer shape of each of the screwing portions 41r and 42r is formed in a shape that meshes with a tool such as a wrench. Here, the case where the external shape of each of the screwing portions 41r and 42r is a hexagonal column shape meshing with a hexagonal wrench is illustrated.

  The direction in which the female screws of the nut members 41 and 42 are screwed and tightened with respect to the male screw portions 11 and 12, respectively, is referred to as “front”, and the direction in which the female screws are retracted is referred to as “rear”. Each of the holes 11h and 12h has a single diameter on the front end side, which is about half the total length, and the rear end side increases in diameter toward the rear end. That is, the inner peripheral surfaces of the holes 11h and 12h are tapered surfaces 11s and 12s on the rear end side. The small diameter hole 41 h of the nut member 41 has the same diameter as the single diameter portion of the hole 11 h of the male screw portion 11, and this diameter is slightly larger than the outer diameter of the cylindrical portion 51 b of the sensor element 51. The small-diameter hole 42 h of the nut member 42 has the same diameter as the single-diameter portion of the hole 12 h of the male screw portion 12, and this diameter is slightly larger than the outer diameter of the holder 52.

  The hole 10h of the base 10r is smaller in diameter than the hole 11h on the male screw 11 side and smaller in diameter than the hole 12h on the male screw 12 side. Thereby, at the boundary between the male screw portion 11 and the base portion 10r, the base portion 10r projects in an annular shape from the edge of the hole portion 11h toward the inside, and at the boundary between the male screw portion 12 and the base portion 10r, The base portion 10r projects in an annular shape from the edge of the hole portion 12h toward the inside.

  The paired front ferrule 21 and back ferrule 31 both correspond to the annular member of the present invention, and are interposed between the male screw portion 11 and the nut member 41. Since the front ferrule 21 has a conical outer shape whose rear end has a larger diameter than the front end, the outer peripheral surface is a tapered surface 21t. The inner peripheral surface of the front ferrule 21 is a tapered surface 21s whose diameter increases toward the rear end on the rear end side. When the inclination of the taper surface 21t of the front ferrule 21 and the inclination of the taper surface 11s of the male screw portion 11 are compared in terms of an angle with respect to the axial direction (center axis of the holes 11h, 10h, and 12h), the taper surface 11s is better. The inclination angle is larger than that of the tapered surface 21t.

  On the other hand, the back ferrule 31 has a conical outer shape whose rear end has a larger diameter than the front end, and therefore the outer peripheral surface is a tapered surface 31t. When the inclination of the taper surface 31t and the inclination of the taper surface 21s on the inner periphery of the front ferrule 21 are compared with respect to the axial direction, the taper surface 21s has a larger inclination angle than the taper surface 31t. At the rear end of the back ferrule 31, an annular flange portion 31f projects outward.

  The other front ferrule 22 and back ferrule 32 forming a pair both correspond to the annular member of the present invention, and are interposed between the male screw portion 12 and the nut member 42. The configuration of each of the front ferrule 22 and the back ferrule 32 and the relationship between them, and the relationship between the front ferrule 22 and the male screw portion 12, the configuration of each of the front ferrule 21 and the back ferrule 31 and the relationship between each other, and the front ferrule 21 and the male ferrule 21. The relationship with the screw portion 11 is the same. That is, since the front ferrule 22 has a conical outer shape whose rear end has a larger diameter than the front end, the outer peripheral surface is a tapered surface 22t. The inner peripheral surface of the front ferrule 22 is a tapered surface 22s whose diameter increases toward the rear end on the rear end side. When the inclination of the tapered surface 22t of the front ferrule 22 and the inclination of the tapered surface 12s of the male screw portion 12 are compared with respect to the axial direction, the tapered surface 12s has a larger inclination angle than the tapered surface 22t.

  On the other hand, the back ferrule 32 has a conical outer shape whose rear end has a larger diameter than the front end, and therefore the outer peripheral surface is a tapered surface 32t. When the inclination of the taper surface 32t and the inclination of the taper surface 22s on the inner periphery of the front ferrule 22 are compared with respect to the axial direction, the taper surface 22s has a larger inclination angle than the taper surface 32t. At the rear end of the back ferrule 32, an annular flange portion 32f projects outward.

  In order to manufacture the solid electrolyte sensor 1 having the above configuration, the cylindrical portion 51 b of the sensor element 51 is connected to the male screw portion 11 of the sealing member 50, while the holder 52 is connected to the male screw portion 12 of the sealing member 50. To do. As a result, one end of the holder 52 is closed by the sensor element 51 via the sealing member 50 to form a bottomed cylindrical shape as a whole.

  First, the connection between the holder 52 and the sealing member 50 will be described. Here, in order to contrast the connection between the sealing member 50, which is a double ferrule-type joint, and the sensor element 51 made of ceramics with a conventional connection in which a material that can be penetrated by the ferrule is a connection target, the holder 52 is made of metal. The case where it is made is illustrated.

  The holder 52 is inserted into the hole 12 h of the male screw portion 12 with one end of the holder 52 inserted through the front ferrule 22 and the back ferrule 32. At the boundary between the male screw portion 12 and the base portion 10r, the base portion 10r protrudes in an annular shape from the edge of the hole portion 12h toward the inside, so that the end portion of the holder 52 abuts against this protruding portion. Can be inserted. Further, the holder 52 is inserted into the small diameter hole 42h of the nut member 42 with the screwing portion 42r facing the male screw portion 12 side. In this state, when the female screw hole 42n of the nut member 42 is screwed into the male screw portion 12 and the nut member 42 is tightened with respect to the male screw portion 12, the back ferrule 32 is pressed against the bottom wall portion 42g of the nut member 42. It is. Since the back ferrule 32 has the flange portion 32 f at the rear end, the pressing force from the nut member 42 is easily transmitted to the back ferrule 32. Since the outer peripheral surface of the back ferrule 32 is a tapered surface 32t and the inner peripheral surface of the front ferrule 22 is a tapered surface 22s on the rear end side, the front end of the back ferrule 32 is recessed inward from the tapered surface 22s of the front ferrule 22. To move forward. Since the inclination angle of the taper surface 22s is larger than the inclination angle of the taper surface 32t, the front end of the back ferrule 32 can easily move forward so as to go inward from the taper surface 22s.

  Thereby, the front ferrule 22 pushed by the back ferrule 32 moves forward while being deformed so as to be pushed outward. Since the outer peripheral surface of the front ferrule 22 is a tapered surface 22t and the inner peripheral surface of the male screw portion 12 is a tapered surface 12s on the rear end side, the front end of the front ferrule 22 is inward of the tapered surface 12s of the male screw portion 12. Move forward to crawl into. Since the inclination angle of the taper surface 12s is larger than the inclination angle of the taper surface 22t, the front end of the front ferrule 22 is easy to move forward so as to go inward from the taper surface 12s.

  When the nut member 42 is sufficiently tightened with respect to the male screw portion 12, the outer peripheral surface (tapered surface 22t) of the front ferrule 22 that is pushed outward is the inner peripheral surface of the hole portion 12h of the male screw portion 12 ( The taper surface 12s) is pressed into close contact. Further, the outer peripheral surface (tapered surface 32t) of the back ferrule 32 is pressed against and closely adhered to the inner peripheral surface (tapered surface 22s) of the front ferrule 22. The front end of the front ferrule 22 that is recessed inward from the tapered surface 12s of the male screw portion 12 and the front end of the back ferrule 32 that is recessed inward from the tapered surface 22s of the front ferrule 22 are reduced in diameter. It plastically deforms and bites into the metal holder 52 like a wedge. Thereby, the holder 52 is closely connected with respect to the coupling main body 10 (refer the upper part in FIG.3 (b)). In addition, since the external shape of each of the base portion 10r of the joint body 10 and the screwing portion 42r of the nut member 42 is a shape that meshes with a tool, a nut member is used with respect to the male screw portion 12 by using a tool such as a wrench. 42 can be tightened sufficiently.

  Next, the connection between the cylindrical portion 51b of the ceramic sensor element 51 and the sealing member 50 will be described. By tightening the nut member 41 with respect to the male screw portion 11, the back ferrule 31 is pushed by the bottom wall portion 41g of the nut member 41, and the front ferrule 21 is pushed by the back ferrule 31 and is plastically deformed while moving forward. The same as above. However, the front ferrule 21 and the back ferrule 31 that are plastically deformed do not bite into the cylindrical portion 51b of the sensor element 51 made of ceramics, which is different from the above case where the connection target is made of metal.

  That is, the cylindrical portion 51 b is inserted into the hole portion 11 h of the male screw portion 11 with the end portion of the cylindrical portion 51 b of the sensor element 51 inserted through the front ferrule 21 and the back ferrule 31. At the boundary between the male screw portion 11 and the base portion 10r, the base portion 10r protrudes in an annular shape from the edge of the hole portion 11h toward the inside, so that the end portion of the cylindrical portion 51b abuts against the protruding portion. Can be inserted into. Further, the cylindrical portion 51b is inserted into the small diameter hole 41h of the nut member 41 with the screwing portion 41r facing the male screw portion 11 side. In this state, when the nut member 41 is tightened against the male screw portion 11, the back ferrule 31 is pushed by the bottom wall portion 41 g of the nut member 41. Since the outer peripheral surface of the back ferrule 31 is a tapered surface 31t and the inner peripheral surface of the front ferrule 21 is a tapered surface 21s on the rear end side, the front end of the back ferrule 31 is recessed inward from the tapered surface 21s of the front ferrule 21. To move forward. Since the inclination angle of the taper surface 21s is larger than the inclination angle of the taper surface 31t, the front end of the back ferrule 31 is likely to move forward inwardly of the taper surface 21s.

  Thereby, the front ferrule 21 pushed by the back ferrule 31 moves forward while being deformed so as to be spread outward. Since the outer peripheral surface of the front ferrule 21 is a tapered surface 21t and the inner peripheral surface of the male screw portion 11 is a tapered surface 11s on the rear end side, the front end of the front ferrule 21 is inward of the tapered surface 11s of the male screw portion 11. Move forward to crawl into. Since the inclination angle of the taper surface 11s is larger than the inclination angle of the taper surface 21t, the front end of the front ferrule 21 is likely to move forward inwardly from the taper surface 11s.

  When the nut member 41 is sufficiently tightened with respect to the male screw portion 11, the outer peripheral surface (taper surface 21t) of the front ferrule 21 pushed outward is the inner peripheral surface (taper surface 11s) of the male screw portion 11. It is pressed against and comes into close contact. Further, the outer peripheral surface (tapered surface 31t) of the back ferrule 31 is pressed against and closely contacts the inner peripheral surface (tapered surface 21s) of the front ferrule 21.

  Since the front end side of the front ferrule 21 that is recessed inward from the tapered surface 11 s of the male screw portion 11 does not bite into the cylindrical portion 51 b of the sensor element 51 made of ceramics, it is plastically deformed by the pressing force of the back ferrule 31. It spreads along the outer peripheral surface of the cylindrical part 51b and adheres. The front end side of the back ferrule 31 that has entered the inner side of the tapered surface 21s of the front ferrule 21 also does not bite into the cylindrical portion 51b of the sensor element 51. Therefore, the front ferrule 21 is plastically deformed by the pressing force of the nut member 41, and the cylindrical portion 51b It spreads along the outer peripheral surface and adheres. Thereby, the space | gap between the internal peripheral surface of the hole 11h of the external thread part 11 and the cylindrical part 51b of the sensor element 51 is filled, and the sensor element 51 is closely connected with respect to the coupling main body 10 (FIG. 3). (See the lower part in (b)).

  As described above, according to the present embodiment, one end of the cylindrical holder 52 is closely connected to the joint body 10, and the cylindrical portion 51 b of the sensor element 51 is closely connected to the joint body 10. Therefore, the bottomed cylindrical internal space in which one end of the holder 52 is closed by the sensor element 51 and the external space are densely partitioned. Thereby, mixing of the gas of two space which pinched | interposed the sensor element 51 can be suppressed effectively.

  Actually, the solid electrolyte sensor 1 of this embodiment was used, and the change in electromotive force when the hydrogen concentration of the measurement gas was changed was measured. The electromotive force was measured at a temperature suitable for use of the sensor element 51 at a temperature of 600 ° C., with the reference gas introduced from the gas introduction pipe 70 to contact the inner electrode 62 and the outer electrode 61 in contact with the measurement gas. . The measurement gas was a mixed gas of hydrogen and argon, and the hydrogen concentration was changed over time.

  When the two spaces between the sensor elements are insufficient, as shown in FIG. 4 (b), when the hydrogen concentration is changed, the electromotive force changes rapidly in response, but the hydrogen concentration is constant. However, the phenomenon that the electromotive force decreases was observed. This was considered because the reference gas and the measurement gas were mixed between the inner space and the outer space of the bottomed cylindrical shape formed by the holder and the sensor element.

  On the other hand, in the solid electrolyte sensor 1 of the present embodiment, as shown in FIG. 4A, when the hydrogen concentration is changed, the electromotive force rapidly changes in response, and while the hydrogen concentration is constant, the electromotive force is changed. Was also held constant. From this, it is considered that the reference gas and the mixed gas are not mixed, and the bottomed cylindrical inner space and the outer space formed by the holder 52 and the sensor element 51 are airtightly partitioned by the sealing member 50. It was.

  Next, the solid electrolyte sensor 2 of the second embodiment will be described with reference to FIG. The solid electrolyte sensor 2 is different from the solid electrolyte sensor 1 in the form of an annular member in the sealing member 50. Specifically, in the solid electrolyte sensor 2, one annular member 31 b and 32 b are interposed between the male screw portions 11 and 12 and the nut members 41 and 42 to be screwed together. The annular members 31b and 32b have a shape in which both ends in the axial direction have the same diameter and are curved outward while expanding toward the middle in the axial direction.

  The diameter of both ends of the annular member 31b is equal to the maximum diameter r of the tapered surface 11s, which is the diameter of the rear end of the hole 11h of the male screw portion 11, and the diameter of both ends of the annular member 32b is the hole of the male screw portion 12. It is equal to the maximum diameter R of the tapered surface 12s which is the diameter of the rear end of the portion 12h. Therefore, in a state where no external force is applied, the annular members 31b and 32b cannot be inserted into the holes 11h and 12h, respectively. Therefore, by tightening the nut members 41 and 42 with respect to the male screw portions 11 and 12, respectively, the end portions of the annular members 31b and 32b are pushed into the holes 11h and 12h while being plastically deformed. Due to the plastic deformation of the annular members 31b and 32b, the gap between the inner peripheral surface of the hole portion 11h and the cylindrical portion 51b of the sensor element 51, and the inner peripheral surface of the hole portion 12h and the holder 52, respectively, as described above. The inner space and the outer space having a bottomed cylindrical shape formed by the holder 52 and the sensor element 51 are hermetically partitioned by the sealing member 50.

  Next, the solid electrolyte sensor 3 of the third embodiment will be described with reference to FIG. The solid electrolyte sensor 3 is different from the solid electrolyte sensors 1 and 2 in the form of an annular member in the sealing member 50. Specifically, in the solid electrolyte sensor 3, the solid electrolyte sensor 2 is different in that there is one annular member interposed between the male screw portions 11 and 12 and the nut members 41 and 42 to be screwed together. However, the shapes of the annular members 31 c and 32 c are different from those of the solid electrolyte sensor 2. The annular members 31c and 32c of the solid electrolyte sensor 3 are circular rings (hollow rings) formed by cylinders.

  The diameter of the circle formed by connecting the centers of the cylinders in the annular member 31c is equal to the maximum diameter r of the tapered surface 11s, which is the diameter of the rear end of the hole 11h of the male screw portion 11, and the center of the cylinder in the annular member 32c. Is equal to the maximum diameter R of the tapered surface 12s, which is the diameter of the rear end of the hole 12h of the male screw portion 12. Therefore, in a state where no external force is applied, the annular members 31c and 32c cannot be inserted into the holes 11h and 12h, respectively. Therefore, by tightening the nut members 41 and 42 with respect to the male screw portions 11 and 12, respectively, the annular members 31c and 32c are pushed into the holes 11h and 12h while being plastically deformed so as to be crushed. Due to the plastic deformation of the annular members 31c and 32c, the gap between the inner peripheral surface of the hole portion 11h and the cylindrical portion 51b of the sensor element 51 and the inner peripheral surface of the hole portion 12h and the holder 52 are respectively similar to the above. The inner space and the outer space having a bottomed cylindrical shape formed by the holder 52 and the sensor element 51 are hermetically partitioned by the sealing member 50.

  The present invention has been described with reference to the preferred embodiments. However, the present invention is not limited to the above-described embodiments, and various improvements can be made without departing from the scope of the present invention as described below. And design changes are possible.

  For example, in the above embodiment, the case where the holder is made of metal is exemplified, but a holder made of ceramics such as alumina can be used. As a result, the sealing member, which is a pipe joint that has been handled by those skilled in the art as a “bite-in type”, is made of a ceramic holder in which the annular member does not bite, and a ceramic sensor element in which the annular member does not bite. And a more innovative configuration.

  In the above embodiment, the case where the sizes of the two male screw portions 11 and 12 of the joint body 10 are different is illustrated, but the size of the two male screw portions as in the solid electrolyte sensor 1b shown in FIG. Can be the same. In this case, the sizes of the nut members 41 and 42 are also the same, and annular members (a pair of the front ferrule 21 and the back ferrule 31 in FIG. 5, respectively) interposed between the male screw portions 11 and 12 and the nut members 41 and 42. The sizes of the front ferrule 22 and the back ferrule 32) are also the same.

  With this configuration, the diameter of the cylindrical portion 51b of the sensor element 51 can be made the same as the diameter of the holder 52. Therefore, the gas introduction pipe 70 is extended to the inside of the sensor element, and the tip thereof is the inner electrode 62. Can be located in the vicinity. Thereby, the contact between the reference gas or the measurement gas and the inner electrode 62 becomes better, and the gas concentration can be detected more accurately. Further, since the outer diameter of the sensor element 51 is larger than that of the solid electrolyte sensor 1, the sensor element 51 can be made thick. Thereby, since the mechanical strength of the sensor element 51 increases, when the nut member 41 is tightened with respect to the male screw portion 11, the resistance of the ceramic sensor element 51 to the force pressed from the outside by the annular member is increased. Can do.

1, 1b, 2, 3 Solid electrolyte sensor 10 Joint body 21, 22 Front ferrule (annular member)
31, 32 Back ferrule (annular member)
31b, 32b annular members 31c, 32c annular members 41, 42 nut member 50 sealing member 51 sensor element 51b cylindrical portion 52 holder 70 gas introduction pipe

Claims (4)

A bottomed cylinder in which one end of the holder is closed by the sensor element by connecting one end of the cylindrical holder and a cylindrical part of the bottomed cylindrical sensor element made of solid electrolyte ceramics by a sealing member. A solid electrolyte sensor in which a shaped internal space and an external space are partitioned,
The sealing member is
A joint main body having a male screw portion protruding in opposite directions, and a hole portion passing through each of the two male screw portions in the axial direction;
Two nut members having female screw holes respectively screwed into the two male screw portions;
Two or two pairs of metal annular members respectively interposed between the two male screw portions and the nut member of the screwing counterpart,
With the holder inserted into the hole of one of the male screw portions, the male screw portion and one of the female screw holes are screwed together and the nut member is tightened, so that one of the annular members is While plastically deforming and closing between the inner peripheral surface of the hole and the holder,
In the state where the cylindrical portion of the sensor element is inserted into the hole portion of the other male screw portion, the nut member is tightened by screwing the male screw portion and the other female screw hole. A method of manufacturing a solid electrolyte sensor, wherein the annular member is plastically deformed to close a space between an inner peripheral surface of the hole and the sensor element. A cylindrical holder;
A bottomed cylindrical sensor element made of solid electrolyte ceramics;
By connecting a cylindrical portion of the sensor element to one end of the holder, a sealing member that divides a bottomed cylindrical internal space in which one end of the holder is closed with the sensor element from an external space, Equipped,
The sealing member is
A joint main body having a male screw portion protruding in opposite directions, and a hole portion passing through each of the two male screw portions in the axial direction;
Two nut members having female screw holes respectively screwed into the two male screw portions;
Two or two pairs of metal annular members respectively interposed between the two male screw portions and the nut member of the screwing counterpart,
One of the annular members has an inner periphery of the hole portion in a state where the holder is inserted into the hole portion of the one male screw portion and the male screw portion and the one female screw hole are screwed together. Plastic deformation between the surface and the holder,
The other annular member has the cylindrical portion of the sensor element inserted into the hole portion of the other male screw portion, and the male screw portion and the other female screw hole are screwed together. A solid electrolyte sensor, wherein the sensor element is plastically deformed between an inner peripheral surface of the portion and the sensor element. The solid electrolyte sensor according to claim 2, wherein the holder is made of ceramics. 4. The solid electrolyte sensor according to claim 2, wherein the sealing member is a double ferrule-type joint including two pairs of a front ferrule and a back ferrule that form a pair as the annular member.

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