JP7432429B2 - solid electrolyte sensor - Google Patents

Description

The present invention relates to a solid electrolyte sensor that detects gas concentration using a solid electrolyte as a sensor element.

Various solid electrolyte sensors have been proposed that use solid electrolytes (ion-conductive ceramics) as sensor elements to detect gas concentrations such as hydrogen gas, oxygen gas, carbon dioxide gas, and water vapor, and the applicant has also made several proposals in the past. Is going. The solid electrolyte sensor uses the principle of a concentration cell, in which a potential difference occurs due to the difference in the concentration of the same ion. Measure power. If the concentration of the gas to be detected in the first of the two spaces is known, the gas concentration in the second space can be determined from the measured electromotive force and the temperature of the sensor element using Nernst's equation. can. Alternatively, by measuring the electromotive force by changing the gas concentration in the second space while keeping the gas concentration in the first space constant, and investigating the correlation between the gas concentration and the electromotive force in advance, The gas concentration in the second space can be known from the measured value of the electromotive force when the gas concentration is unknown.

In conventional solid electrolyte sensors, a reference gas with a known concentration of the target gas to be detected is introduced into the space (hereinafter referred to as the "reference gas space") out of two spaces through a resin-based flexible tube. In addition to guiding the reference gas, the reference gas was also discharged from the reference gas space to the outside of the system via a resin-based flexible tube. A resin-based flexible tube has the advantage that the gas line can be set arbitrarily.

However, depending on the site where the solid electrolyte sensor is used, the presence or absence of a gas leak may be checked by introducing pressurized gas into the gas line before starting measurement. Since resin-based flexible tubes have low pressure resistance, there is a risk that they will break during such gas leakage checks. Furthermore, since the resin-based flexible tube does not have high gas barrier properties, it was not possible to deny the possibility that a very small amount of gas was leaking through the tube wall.

Japanese Patent Application Publication No. 2011-174832

Therefore, in view of the above-mentioned circumstances, the present invention makes it possible to introduce gas into one of two spaces partitioned by a solid electrolyte sensor element fixed to a holder without gas leakage. It is an object of the present invention to provide a solid electrolyte sensor that can discharge gas without gas leakage.

In order to solve the above problems, the solid electrolyte sensor according to the present invention includes:
"A solid electrolyte sensor in which a first space and a second space are partitioned by fixing a solid electrolyte sensor element to a holder,
a head portion whose internal space communicates with the first space;
A gas introduction pipe made of metal or ceramics, one end of which is inserted into the first space, and the other end of which passes through the head portion;
The head portion communicates an internal space with a first opening to which the holder is connected, a second opening to which a joint integrated with the gas introduction pipe is connected, and an external space of the head portion. It has a gas exhaust pipe that allows
The flange portion extending outward from the opening edge of the first opening is in contact with the flange portion of the holder via an O-ring, and the flange portion extends outward from the opening edge of the second opening. The flange portion is in contact with the flange portion of the joint via an O-ring.

Alternatively, the solid electrolyte sensor according to the present invention has the above configuration,
"A solid electrolyte sensor in which a first space and a second space are partitioned by fixing a solid electrolyte sensor element to a holder,
a head portion whose internal space communicates with the first space;
A gas introduction pipe made of metal or ceramics, one end of which is inserted into the first space, and the other end of which passes through the head portion;
The head part is integrated with the holder, and has a second opening to which a joint integrated with the gas introduction pipe is connected, and a gas exhaust pipe that communicates the internal space with the external space of the head part. It has
The flange portion projecting outward from the opening edge of the second opening may be in contact with the flange portion of the joint via an O-ring.

Furthermore, the solid electrolyte sensor according to the present invention has the above configuration,
“The head portion has a third opening to which a terminal block is connected,
The flange portion projecting outward from the opening edge of the third opening may be in contact with the flange portion of the terminal block via an O-ring.

The solid electrolyte sensor of the present invention includes a head portion. The internal space of the head portion communicates with a first space, one of the two partitioned spaces. The head part has a first opening with a holder as a connection partner, a second opening with a joint integrated with the gas introduction pipe as a connection partner, and a second opening with a terminal block as a connection partner. It has at least the second opening among the three openings. The head portion may be integral with the holder without having the first opening, and the terminal block may be fixed to the head portion without having the third opening.

The second opening has a flange portion projecting outward from the edge of the opening, and the joint, which is a mating member for connection, also has a flange portion. In addition, when the first opening or the third opening is provided, they also have a flange portion protruding outward from the opening edge, and the holder and terminal block that are the mating members for each connection are also , each having a flange portion. The manner in which the mating members are connected to each opening in the head portion is such that the flange portions are brought into contact with each other with an O-ring interposed therebetween.

In such a configuration, if the head part, its flange part, and the flange part of the mating member to be connected are made of a material that is not gas permeable, such as metal, the only member that affects gas permeability is the O-ring. . Therefore, by using an O-ring made of a material with high gas barrier properties such as fluorocarbon rubber, the head part can be made into an airtight structure that is connected to the external space only through the gas exhaust pipe and the gas introduction pipe. Conventionally, gas lines for introducing and discharging gas were formed using flexible tubes, but it was impossible to improve the gas barrier properties over the entire length of the gas lines. On the other hand, since it is possible to select an O-ring made of a material with high gas barrier properties, gas can be introduced into the first space without gas leakage, and gas can also be discharged without gas leakage. can.

In addition, since it is sufficient to replace only the O-ring with use, maintenance is extremely easy compared to replacing the entire length of the flexible tube and resetting the gas line.

Since the head part has an airtight structure, the gas introduced from the gas introduction pipe fills the first space and then fills the internal space of the head part, and the gas is discharged by the amount of new gas introduced. It is naturally drained from the tube. In other words, this configuration differs from the conventional one in that a gas flow path is formed without using any flexible tubes and without using tubular lines for gas discharge. It is. Note that a tubular structure (gas introduction pipe) is used to introduce gas, but since it is made of metal or ceramics, it has high pressure resistance, so it can be used even when pressurized gas is introduced to check for gas leaks. , there is no risk of breakage or rupture.

In addition to the above configuration, the solid electrolyte sensor according to the present invention has the following features:
"A check valve is provided in a portion of the gas introduction pipe located in the external space of the head part and in the gas discharge pipe, which shuts off the flow of gas when the internal space of the head part becomes negative pressure." It can be assumed that the

The solid electrolyte sensor with this configuration includes a check valve that shuts off the flow of gas through the gas introduction pipe and the gas discharge pipe when the internal space of the head section becomes negative pressure. As a result, even if a crack or crack occurs in the sensor element when the second space is the atmosphere to be measured and the pressure is reduced, the internal space of the head section will be under negative pressure, allowing the gas to flow. is blocked, it is possible to effectively reduce the risk of outside air entering the industrial furnace, which is the atmosphere to be measured, and the risk of gas inside the industrial furnace leaking out of the system.

As described above, according to the present invention, gas can be introduced into one of the two spaces partitioned by the solid electrolyte sensor element fixed to the holder without gas leakage, Moreover, it is possible to provide a solid electrolyte sensor that can discharge gas without gas leakage.

FIG. 1 is an exploded perspective view of a sensor element and a holder in a solid electrolyte sensor according to an embodiment of the present invention. (a) is an exploded cross-sectional view illustrating fixing of the sensor element to the holder, and (b) is a longitudinal cross-sectional view of the sensor element fixed to the holder. FIG. 2 is an exploded perspective view illustrating fixing of a gas introduction pipe to a holder to which a sensor element is fixed. It is an exploded perspective view explaining connection of a holder, a gas introduction pipe, and a terminal block to a head part. (a) A perspective view of the head section seen from a direction different from that shown in FIG. 4, (b) A perspective view of a part of the joint integrated with the gas introduction pipe seen from a direction different from that shown in FIG. 4, (c) FIG. FIG. 5 is an exploded perspective view of the terminal block of FIG. 4; and FIG. FIG. 3 is a vertical cross-sectional view of the solid electrolyte sensor cut at the center.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A solid electrolyte sensor 1, which is a specific embodiment of the present invention, will be described below with reference to the drawings. The solid electrolyte sensor 1 mainly includes a sensor element 10, a holder 20, a gas introduction pipe 40, a head portion 50, and a terminal block 70.

The holder 20 is made of metal such as stainless steel, and includes a cylindrical tube portion 21, a bottom portion 22 that closes one end of the tube portion 21, and a flange portion 25 that projects outward from the other end of the tube portion 21. We are prepared. A plurality of ventilation holes 24 are provided in the cylindrical portion 21 in the vicinity of the bottom portion 22 and in the bottom portion 22 . Note that instead of providing the ventilation hole 24, a holder without a bottom (a holder consisting of a cylindrical portion 21 with a flange portion 25) may be used.

The sensor element 10 has a shape in which a bottomed cylindrical element body 11 and a flange portion 15 projecting outward from the opening edge of the element body 11 are integrally formed of a solid electrolyte. The outer diameter of the element body 11 is smaller than the inner diameter of the cylindrical part 21 of the holder 20, and the outer diameter of the flange part 15 of the sensor element 10 is larger than the inner diameter of the cylindrical part 21 of the holder 20. Therefore, with the element main body 11 inserted into the internal space of the cylindrical part 21 of the holder 20, the sensor element 10 is placed on the end surface of the flange part 25 side of the cylindrical part 21 of the holder 20 (hereinafter referred to as "open end surface"). The flange portion 15 can be brought into contact with it.

A first O-ring 31 is interposed between the flange portion 15 of the sensor element 10 and the open end surface of the holder 20. The first O-ring 31 has an inner diameter larger than the outer diameter of the element body 11. Note that a first recess 25r into which the first O-ring 31 can be fitted is formed on the open end surface of the holder 20.

In this embodiment, a second O-ring 32 having the same size as the first O-ring 31 is used, and the flange portion 15 of the sensor element 10 is sandwiched between the first O-ring 31 and the second O-ring 32. I'm here. Furthermore, a disc-shaped pressure contact plate 35 is brought into contact with the second O-ring 32. The outer diameter of the pressure contact plate 35 is larger than the outer diameter of the O-rings 31 and 32 and the outer diameter of the flange portion 15 of the sensor element 10, and a hole 35h of the same size as the inner diameter of the element body 11 is provided in the center. has been done. In addition, a second recess 35r, into which the second O-ring 32 can be fitted, is formed on the surface of the pressure contact plate 35 that is brought into contact with the second O-ring 32, and whose depth is smaller than the thickness of the second O-ring. It is formed. Further, the pressure contact plate 35 is provided with a plurality of small holes 35p through which small bolts 37 are passed. On the other hand, a thread groove 27 is formed in the flange 25 of the holder 20 in a positional relationship corresponding to the plurality of small holes 35p and is threaded into the male thread of the bolt 37.

With the above configuration, the pressure contact plate 35 is brought into contact with the second O-ring 32, and the bolt 37 passed through the small hole 35p of the pressure contact plate 35 is fastened to the thread groove 27 of the flange portion 25 of the holder 20. The flange portion 15 of the sensor element 10 sandwiched between the O-ring 31 and the second O-ring 32 is pressed against the open end surface of the holder 20 by the pressure contact plate 35. Thereby, a first space S1, which is an internal space of the sensor element 10 having a bottomed cylindrical shape, and a second space S2, which is an external space, are partitioned. Since the flange portion 15 of the sensor element 10 is in close contact with the open end surface of the holder 20 via the first O-ring 31, the first space S1 and the second space S2 are airtightly partitioned. Here, by using a fluorine-based rubber O-ring with high gas barrier properties and excellent heat resistance as the first O-ring 31, in the solid electrolyte sensor 1 used at high temperatures, the first space S1 and the second space The space S2 can be partitioned with extremely high airtightness.

Since the second O-ring 32 is interposed between the flange portion 15 of the sensor element 10 and the pressure contact plate 35, the stress acting from the pressure contact plate 35 on the flange portion 15 of the sensor element 10, which is a brittle material, is reduced. A portion of the flange portion 15 can be absorbed by the second O-ring 32, and the flange portion 15 can be sufficiently pressed against the open end surface of the holder 20 while suppressing the occurrence of cracks or cracks in the flange portion 15.

Although not shown, a first electrode is provided on the surface of the sensor element 10 that is in contact with the first space S1, a second electrode is provided on the surface that is in contact with the second space S2, and a second electrode is provided on the surface that is in contact with the second space S2. An electromotive force generated between one electrode and a second electrode is measured.

Of the first space S1 and the second space S2, the first space S1 is a space into which a reference gas whose concentration of the gas to be detected is known is introduced, and the second space S2 is the atmosphere to be measured in which the gas concentration is measured. This is a space that is communicated with through the ventilation hole 24. Therefore, in the solid electrolyte sensor 1, in the holder 20 to which the sensor element 10 is fixed as described above, the part closer to the bottom part 22 than the flange part 25 is inserted into the internal space of the industrial furnace, which is the atmosphere to be measured. used in The cylindrical portion 21 of the holder 20 can further be provided with a member for fixing the holder 20 to the furnace wall of the industrial furnace.

In the solid electrolyte sensor 1 of this embodiment, the sensor element 10 includes a flange portion 15, and the flange portion 15 is brought into contact with the open end surface of the holder 20 with the element body 11 positioned in the internal space of the holder 20. ing. Therefore, even if the second space S2, which is the space to be measured, is depressurized and a force is applied to the element body 11 to draw it into the second space S2, the sensor element 10 will not shift relative to the holder 20. The state in which the sensor element 10 is firmly and stably supported by the holder 20 continues.

A gas introduction pipe 40 for introducing a reference gas is inserted into the first space S1. The gas introduction pipe 40 is a cylinder made of metal such as stainless steel, and has a small diameter part 41 that can be inserted into the internal space of the cylindrical part 21 of the holder 20, and a general pipe that supplies a reference gas from outside the system to the solid electrolyte sensor 1. It has a large diameter part 42 whose diameter corresponds to that of a typical pipe, and a joint 43 which connects the small diameter part 41 and the large diameter part 42.

The joint 43 is a biting type joint, and although detailed illustration is omitted, two male threaded parts protrude in opposite directions, and a hole passing through each male threaded part in the axial direction communicates with each other. It has a joint main body, a female threaded part that screws into each male threaded part, and an annular part that is pushed into the hole of the male threaded part by tightening the female threaded part to each male threaded part. ing. In the joint 43, the diameters of the holes in the two male threaded portions are different; one diameter is slightly larger than the outer diameter of the small diameter portion 41, and the other diameter is slightly larger than the outer diameter of the large diameter portion 42. Then, with the small diameter part 41 inserted into the hole of one male threaded part and the large diameter part 42 inserted into the hole of the other male threaded part, tighten the female threaded part into each male threaded part. As a result, each annular portion is plastically deformed to reduce its diameter and is pushed into the hole, and bites into the outer peripheral surfaces of the small diameter portion 41 and the large diameter portion 42, respectively. Thereby, the small diameter portion 41 and the large diameter portion 42 are airtightly connected via the joint 43.

In addition, in the gas introduction pipe 40, at least one of the small diameter part 41 and the large diameter part 42 can be made of a ceramic pipe such as alumina or zirconia. In this case, the annular portion of the joint 43 does not bite into the outer circumferential surface of the ceramic tube, but spreads along the outer circumferential surface due to plastic deformation and comes into close contact with the outer circumferential surface.

A stopper 46 having a diameter larger than the outer diameter of the small diameter portion 41 is fixed in the middle of the small diameter portion 41 . A compression coil spring 47 is inserted through the small diameter portion 41 on the side closer to the joint 43 than the stopper 46 . The compression coil spring 47 has a smaller diameter than the stopper 46. Further, a fixing plate 45 is inserted through the small diameter portion 41 on the side closer to the joint 43 than the compression coil spring 47 . The fixing plate 45 has a disk shape with a larger diameter than the pressure contact plate 35, and has a hole 45h in the center thereof, and the small diameter portion 41 is inserted through the hole 45h. This hole 45h has a smaller diameter than the compression coil spring 47. That is, in the small diameter part 41, the compression coil spring 47 and the hole 45h of the fixed plate 45 are passed through the end part connected to the large diameter part 42 from the stopper 46, and the small diameter part 41 is connected to the large diameter part by the joint 43. 42.

A plurality of small holes 45p are provided through the fixed plate 45. On the other hand, a plurality of male threaded shafts 28 are arranged on the flange portion 25 of the holder 20 in a positional relationship corresponding to the plurality of small holes 45p. The outer diameter of the male threaded shaft 28 is smaller than the diameter of the small hole 45p, and the male threaded shaft 28 extends perpendicularly to the flange portion 25, that is, parallel to the axial direction of the cylindrical portion 21 of the holder 20. With such a configuration, the gas introduction pipe 40 is fixed to the holder 20 by passing the male screw shafts 28 through the small holes 45p of the fixing plate 45 and fastening them with nuts 48. At this time, the compression coil spring 47 is slightly compressed between the fixed plate 45 and the stopper 46. As a result, a force is applied from the compression coil spring 47 to the gas introduction pipe 40 toward the bottom 22 of the holder 20, so that the open end of the small diameter portion 41 is can be brought into contact with the bottom of the element main body 11 so as to be pressed.

The head part 50 is made of metal such as stainless steel, and is made up of a cylindrical part 50a having a considerably larger diameter than the cylindrical part 21 of the holder 20, and two branch pipes connected to the side surfaces of the cylindrical part 50a. The configuration is as follows. One of the two branch pipes is a terminal block connecting pipe 50b to which the terminal block 70 is connected. The other of the two branch pipes is a small diameter gas exhaust pipe 50c. The portion of the gas introduction pipe 40 that is exposed from the flange portion 25 of the holder 20 is inserted through the first opening 51h, which is one opening of the cylindrical portion 50a of the head portion 50, and opens the internal space of the cylindrical portion 50a. After passing through, it is drawn out to the external space of the head section 50 from the second opening 52h, which is the other opening of the cylindrical section 50a.

Flange portions 51 and 52 project outward from the opening edges of the first opening 51h and the second opening 52h, respectively. Further, the flange portion 53 similarly projects outward from the opening edge of the third opening portion 53h, which is the opening of the terminal connection tube 50b.

The flange portion 51 of the head portion 50 is brought into contact with the flange portion 25 of the holder 20 via an O-ring 81r. Specifically, a joint 81 is used in which an O-ring 81r is attached to the outer periphery of a metal inner ring 81i. A circular groove 26 into which the inner ring 81i is fitted is formed in the flange portion 25 of the holder 20. On the other hand, the diameter of the first opening 51h is larger than the outer diameter of the inner ring 81i and smaller than the outer diameter of the O-ring 81r. Therefore, by fitting the inner ring 81i into the circular groove 26 and supporting the joint 81 on the flange portion 25 of the holder 20, the O-ring 81r The flange portion 25 and the flange portion 51 are in close contact with each other via the flange portion 25 and the flange portion 51. Then, by clamping the overlapping flange parts 25 and 51 with a clamp (not shown), the holder 20 and the head part 50 are airtightly connected.

A joint 60 that is integrated with the gas introduction pipe 40 is attached to the flange portion 52 of the head portion 50 via an O-ring 82r. Specifically, the joint 60 is made of metal such as stainless steel, and includes a cylindrical portion 61 into which the large diameter portion 42 of the gas introduction pipe 40 is inserted, and a male thread formed at one end. A hole 62h having a flange portion 65 projecting outward from the other end of the portion 61 and a female thread that engages with the male thread of the cylindrical portion 61 and having a size through which the large diameter portion 42 is inserted is provided. A nut portion 62 is provided.

The gas introduction pipe 40 is integrated with the joint 60 by inserting its large diameter part 42 through the cylinder part 61 and nut part 62 of the joint 60, and then tightening the female thread of the nut part 62 to the male thread of the cylinder part 61. has been made into At this time, the gas introduction pipe 40 and the joint 60 are integrated in an airtight manner by fitting O-rings 67 and 68 between the outer peripheral surfaces of the large diameter portion 42 at both ends of the cylindrical portion 61, respectively.

On the other hand, a tubular portion 52i is formed at the opening edge of the second opening 52h of the head portion 50 so as to protrude from the surface of the flange portion 52, and an O-ring 82r is attached to the outer periphery of the tubular portion 52i. There is. The flange portion 65 of the joint 60 has a tubular flat portion 65f that is flat along the outer periphery on the surface opposite to the side where the cylindrical portion 61 extends, and the inside of the tubular flat portion 65f is recessed. . The inner diameter of the tubular flat portion 65f is larger than the outer diameter of the tubular portion 52i and smaller than the outer diameter of the O-ring 82r.

With this configuration, when the flange portion 65 of the joint 60 integrated with the gas introduction pipe 40 is overlapped with the flange portion 52 of the head portion 50 with the O-ring 82r attached to the tubular portion 52i, the flange The tubular flat portion 65f of the portion 65 and the flange portion 52 are in close contact with each other via an O-ring 82r. Then, by clamping the overlapping flange parts 65 and 52 with clamps (not shown), the joint 60 integrated with the gas introduction pipe 40 and the head part 50 are airtightly connected.

A terminal block 70 is attached to the flange portion 53 of the head portion 50 via an O-ring 83r. Specifically, a joint 83 is used in which an O-ring 83r is attached to the outer periphery of a metal inner ring 83i. The terminal block 70 includes a terminal block main body 71 holding a plurality of pins 70p, and a flange portion 75 projecting outward from the terminal block main body 71. A circular groove 76 into which the inner ring 83i is fitted is formed on one side of the flange portion 75. On the other hand, the diameter of the third opening 53h is larger than the outer diameter of the inner ring 83i and smaller than the outer diameter of the O-ring 83r. Therefore, by fitting the inner ring 83i into the circular groove 76 so that the joint 83 is supported by the flange part 75 of the terminal block 70, and by superimposing the flange part 53 of the head part 50 on the flange part 75, the O-ring The flange portion 75 and the flange portion 53 are in close contact with each other via 83r. Then, by clamping the overlapping flange portions 75 and 53 with a clamp (not shown), the terminal block 70 and the head portion 50 are airtightly connected.

In the terminal block 70, the flange portion 75 may be welded or otherwise fixed to the terminal block main body 71, but in this embodiment, it is separate from the terminal block main body 71. Specifically, the terminal block main body 71 includes a cylindrical male screw portion 71s in which a male screw is formed, a flange portion 71f that is integrated with the male screw portion 71s and projects outward, and an end of the male screw portion 71s. The pin 70p has an electrically insulating bottom portion 71b that closes the bottom portion, and a pin 70p passes through the bottom portion 71b. The pin 70p and the bottom portion 71b, and the bottom portion 71b and the male screw portion 71s are hermetically sealed with a resin sealant. The flange portion 75 is disc-shaped and has a hole portion 75h having a slightly larger diameter than the outer diameter of the male screw portion 71s. The flange portion 75 has a male threaded portion 71s inserted through a hole 75h with an O-ring 72 interposed therebetween, and a nut 74 is fastened to the male threaded portion 71s via a washer 73. By tightening the nut 74 onto the male threaded portion 71s, the flange portion 75 is brought into pressure contact with the flange portion 71f and hermetically sealed by the O-ring 72. Therefore, as described above, by bringing the flange portion 75 into close contact with the flange portion 53 of the third opening 53h, the entire terminal block 70 is airtightly connected to the head portion 50.

As described above, by connecting the holder 20, the joint 60 integrated with the gas introduction pipe 40, and the terminal block 70 to the head section 50, the internal space of the head section 50 is communicated with the first space S1. In addition, the head portion 50 can have an airtight structure in which it is connected to the external space only through the gas introduction pipe 40 and the gas discharge pipe 50c.

The head part 50 is made of metal, and the connections between the holder 20, the joint 60, and the terminal block 70 are made between metal flanges (flange part 25 and flange part 51, flange part 65 and flange part 52). , the flange portion 75 and the flange portion 53) are brought into close contact via O-rings 81r, 82r, and 83r. Therefore, by using O-rings made of a material with high gas barrier properties such as fluorocarbon rubber as the O-rings 81r, 82r, and 83r, the airtightness of the head portion 50 can be greatly improved.

Since the head section 50 has an airtight structure, the reference gas introduced into the first space S1 via the gas introduction pipe 40 fills the internal space of the head section 50 after filling the first space S1. , an amount equivalent to the newly introduced reference gas is discharged to the external space via the gas discharge pipe 50c. Therefore, according to the solid electrolyte sensor 1 of this embodiment, the reference gas can be introduced into the first space S1 without gas leakage, and the reference gas can be discharged without gas leakage.

Note that the first electrode can be provided on the inner peripheral surface of the bottom of the bottomed cylindrical element body 11, and the lead wire (not shown) electrically connected to the first electrode is made of an electrically insulating material. By arranging the small diameter portion 41 of the gas introduction tube 40 in the axial direction along the outer surface thereof, the terminal block 70 can be drawn into the internal space of the head portion 50 through the hole 35h of the pressure contact plate 35. It can be connected to pin 70p of. Further, a thermocouple for measuring the temperature of the sensor element 10 can also be drawn into the internal space of the head section 50 in a similar manner and connected to the pin 70p of the terminal block 70. As described above, since the gas introduction pipe 40 is biased by the compression coil spring 47, the end of the small diameter portion 41 is pressed against the bottom of the element body 11, so that peeling of the first electrode is effectively suppressed. As a result, electromotive force measurement via the lead wire and temperature measurement via the thermocouple can be performed stably and satisfactorily.

On the other hand, the second electrode can be formed by linearly applying an electrode metal paste such as platinum from the outer surface of the element body 11 to the side surface of the flange portion 15 in the sensor element 10 and solidifying the paste. The first electrode formed in this manner is electrically connected to a lead wire (not shown) on the side surface of the flange portion 15, and the lead wire is passed through the gap between the second O-ring 32 and the holder 20 to the head portion. 50 and can be connected to the pin 70p of the terminal block 70. By doing this, in order to fix the sensor element 10 airtightly to the holder 20, the first O-ring 31, which is in close contact with the flange part 15 of the sensor element 10, is not affected. One electrode can be connected to pin 70p of terminal block 70.

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

For example, in the gas introduction pipe 40, a portion extending from the head portion 50 to the external space (portion A indicated by a chain double-dashed line in FIG. 6), and a gas exhaust pipe 50c (portion indicated by a chain double-dashed line in FIG. 6). B) can be provided with a check valve. These check valves are configured such that gas flow is cut off when the internal space of the head portion 50 becomes negative pressure, and ball-type check valves can be used. By having a configuration including such a check valve, if a crack or crack occurs in the sensor element 10 when the atmosphere to be measured is depressurized, the internal space of the head section 50 will become under negative pressure. This blocks the flow of gas through the gas introduction pipe 40 and the gas discharge pipe 50c. This effectively reduces the risk of outside air infiltrating into the industrial furnace, which is the atmosphere to be measured, or the risk of gas inside the industrial furnace leaking out of the system due to cracks or cracks in the sensor element 10. be able to.

Moreover, although the case where the first opening 51h of the head section 50 is airtightly connected to the holder 20 has been described above, the head section 50 can also be integrated with the holder 20. In other words, this configuration corresponds to a configuration in which the first opening 51h of the head portion is fixed to the open end surface of the holder 20.

Further, in the above example, the third opening 53h of the head section 50 is hermetically connected to the terminal block 70, but the terminal block 70 is connected to the head section so that the pin 70p penetrates the peripheral wall of the head section 50. It can also be configured to be fixed to the peripheral wall of 50.

1 Solid electrolyte sensor 10 Sensor element 20 Holder 25 Flange part 40 Gas introduction pipe 50 Head part 50c Gas discharge pipe 51h First opening part 51 Flange part 52h Second opening part 52 Flange part 53h Third opening part 53 Flange part 60 Joint 65 Flange portion 70 Terminal block 75 Flange portions 81r, 82r, 83r O-ring S1 First space S2 Second space

Claims (4)

A solid electrolyte sensor in which a first space and a second space are partitioned by fixing a solid electrolyte sensor element to a holder,
a head portion whose internal space communicates with the first space;
A gas introduction pipe made of metal or ceramics, one end of which is inserted into the first space, and the other end of which passes through the head portion;
The head portion communicates an internal space with a first opening to which the holder is connected, a second opening to which a joint integrated with the gas introduction pipe is connected, and an external space of the head portion. It has a gas exhaust pipe that allows
The flange portion extending outward from the opening edge of the first opening is in contact with the flange portion of the holder via an O-ring, and the flange portion extends outward from the opening edge of the second opening. The solid electrolyte sensor is characterized in that the flange portion of the joint is in contact with the flange portion of the joint via an O-ring. A solid electrolyte sensor in which a first space and a second space are partitioned by fixing a solid electrolyte sensor element to a holder,
a head portion whose internal space communicates with the first space;
A gas introduction pipe made of metal or ceramics, one end of which is inserted into the first space, and the other end of which passes through the head portion;
The head part is integrated with the holder, and has a second opening to which a joint integrated with the gas introduction pipe is connected, and a gas exhaust pipe that communicates the internal space with the external space of the head part. It has
A solid electrolyte sensor characterized in that a flange portion projecting outward from an opening edge of the second opening abuts a flange portion of the joint via an O-ring. The head portion has a third opening to which a terminal block is connected,
3. A flange portion projecting outward from an opening edge of the third opening portion is in contact with a flange portion of the terminal block via an O-ring. solid electrolyte sensor. A check valve is provided in a portion of the gas introduction pipe located in the external space of the head part and in the gas discharge pipe, which blocks the flow of gas when the internal space of the head part becomes negative pressure. The solid electrolyte sensor according to any one of claims 1 to 3, characterized in that:

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