JP2019158824A - Gas sensor - Google Patents

Abstract

To provide a gas sensor which can reduce effect of a temperature from the outside, thus inhibiting reduction in measurement sensitivity of the gas sensor, and which can improve durability of the gas sensor.SOLUTION: A breath sensor includes: a first recess and a first protrusion at an end portion 87 on the side of an opening of a first case 21; and a second protrusion and a second recess at an end portion 97 on the side of an opening of a second case 23. In addition, the first recess of the first case 21 is fitted onto the second protrusion of the second case 23, and the first protrusion of the first case 21 is fitted onto the second recess of the second case 23. Thus, at a fitting portion 85 where the first case 21 and the second case 23 are fitted onto each other, gas such as air is less likely to flow in from the external environment, as compared with in a case where flat surfaces of the first case 21 and the second case 23 are simply in contact with each other. In other words, at the fitting portion 85, a length of a flow path of gas is greater than at portions where the cases are not fitted onto each other.SELECTED DRAWING: Figure 3

Description

  The present disclosure relates to a gas sensor that detects the concentration of a specific gas component contained in a gas to be measured.

Conventionally, for example, for the diagnosis of asthma, a gas sensor that measures NOx at an extremely low concentration (several ppb to several hundred ppb level) in exhaled breath is known (see Patent Document 1).
This gas sensor includes a conversion unit having a catalyst made of PtY (zeolite supporting Pt) for converting NO in exhaled air to NO ₂ and a detection unit having a mixed potential type sensor element for detecting NO _2. The unit is made into one unit by using the stacking technique.

  In this type of gas sensor, the conversion unit is heated by the first heater, and the detection unit is heated by the second heater. The conversion unit and the first heater are covered with a first case to form a first chamber, and the detection unit and the second heater are covered with a second case to form a second chamber. Furthermore, a flow path member that connects the first chamber and the second chamber is provided.

  Then, the exhalation component introduced into the first chamber is converted by the conversion unit heated by the first heater, and the converted exhalation is supplied to the second chamber via the flow path member and detected by the second heater. Based on the electrical change of the part, NOx in exhalation is detected.

US Patent Application Publication No. 2015/0250408

However, the above-described conventional technology has the following problems, and further improvement is required.
Specifically, according to the research of the present inventor, the catalyst of the conversion unit described above has a property of not only converting NO into NO ₂ but also reducing (removing) reducing gases such as H ₂ and CO. Therefore, it has been clarified that when the gas after conversion is supplied to the detection unit, the measurement sensitivity of the gas in the detection unit (that is, the sensitivity when detecting the NO ₂ gas concentration) decreases.

Note that the gas measurement sensitivity in the detection unit is reduced when the detection unit made of, for example, a metal oxide (for example, ZrO ₂ ) is exposed to an oxidizing gas due to a reduction in reducing gas. It is presumed that oxygen vacancies in the object are reduced and oxygen ion movement due to electrode reaction with the oxygen vacancies becomes inactive.

  As a countermeasure, a material that can generate a reducing gas (for example, an organic compound gas such as benzaldehyde) by receiving heat, such as fluororubber, is used as a material for the channel member. Can be generated and supplied to the second chamber.

  However, since the flow path member made of fluororubber or the like has a characteristic that the generation state of the reducing gas changes depending on the temperature of the surrounding environment (that is, the external environment that is the atmosphere), when the temperature of the external environment changes, The generation situation of reducing gas will also change.

  For example, when the gas sensor is placed in a high temperature environment (for example, when stored at a high temperature), a lot of reducing gas may be generated from the flow path member. When using this, only a small amount of reducing gas may be generated from the flow path member.

  As described above, when the generation state of the reducing gas (that is, the amount of reducing gas generated) changes in the flow path member, the amount of reducing gas reaching the detection unit also changes (for example, decreases). The measurement sensitivity when measuring the gas concentration also changes.

  Although it is possible to accommodate the flow path member in the housing together with the conversion unit and the detection unit so that the flow path member is not easily affected by temperature changes in the surrounding environment, the configuration of the housing is not fully studied. Therefore, if outside air such as high-temperature air easily enters the housing during storage of the gas sensor, a large amount of reducing gas is generated from the flow path member. This causes a phenomenon in which only the reducing gas is generated.

  That is, when the gas sensor is used or stored, there is a problem that the measurement sensitivity of the gas sensor becomes unstable because the generation state of the reducing gas changes under the influence of the temperature of the external environment.

  In addition, when reducing gas is excessively generated from the flow path member during storage or the like, the measurement sensitivity decreases when the gas sensor is used, so that there is a problem that the durability (and hence the life) of the gas sensor is decreased. .

  The present disclosure has been made in view of such a background, and an object of the present disclosure is to reduce the influence of external temperature on the gas sensor, and to suppress a decrease in measurement sensitivity of the gas sensor, and to improve the durability of the gas sensor. It is to provide a gas sensor.

(1) A first aspect of the present disclosure relates to a gas sensor including a conversion unit, a detection unit, a flow path member, and a housing.
The conversion unit includes a conversion unit that converts the first gas component in the gas to be measured into the second gas component. The detection unit includes a detection unit that comes into contact with the post-passage gas that is the measurement target gas that has passed through the conversion unit, and whose electrical characteristics change according to the concentration of the second gas component in the measurement target gas.

  The flow path member constitutes a gas flow path of the post-passage gas between the conversion unit and the detection unit. The flow path member includes a specific portion made of a material (for example, a polymer material) that is different from the first gas component and the second gas component and can generate a reducing gas having a reducing property by receiving heat. ing.

  The housing accommodates the conversion unit, the detection unit, and the flow path member. This housing is constructed integrally so as to have a hollow inside with each opening side of a plurality of containers facing each other.

  In this housing, among a plurality of containers, in a pair of containers having facing openings, the container is provided with a recess at the opening side end of one container, and a protrusion is provided at the opening side end of the other container, A pair of containers are integrally formed by fitting the concave and convex portions.

  Thus, in this first aspect, a recess is provided at the opening end of one container, a protrusion is provided at the opening end of the other container, and the recess of one container and the other container are provided. A pair of containers are integrally formed by fitting the convex portions of the two.

  Therefore, the portion where the concave portion and the convex portion of the container are fitted is more easily removed from the external environment than when the end portion of one container and the end portion of the other container are in contact with each other with flat surfaces. It is difficult for gas such as air to flow in. That is, the gas flow path length of the fitted part is increased compared to the non-fitted part.

  Therefore, for example, even when the outside air temperature is high, air or the like having a high temperature hardly enters the inside of the container (and hence the inside of the housing). As a result, for example, even if the outside air temperature becomes high, the temperature inside the housing does not easily rise, so that the temperature of the flow path member (specifically, a specific portion) does not easily rise. Therefore, it can suppress that reducing gas generate | occur | produces from a specific part.

  In other words, in the first aspect, the specific portion of the flow path member in the housing is not easily affected by the temperature of the outside air temperature, so that the generation state of the reducing gas generated from the specific portion can be stabilized. Therefore, the remarkable effect that the measurement sensitivity of a gas sensor can be stabilized is produced.

  In addition, when reducing gas is excessively generated from a specific part, sufficient measurement sensitivity cannot be obtained when using a gas sensor. However, in this first aspect, it is difficult to receive temperature changes in the external environment. It can suppress that reducing gas generate | occur | produces excessively from a part. Therefore, durability of the gas sensor can be enhanced. That is, the life of the gas sensor can be extended.

  As described above, in the first aspect, it is possible to reduce the influence of the temperature from the outside on the gas sensor, to suppress the decrease in measurement sensitivity of the gas sensor, and to achieve the remarkable effect that the durability of the gas sensor can be improved.

  (2) In the second aspect of the present disclosure, the housing includes a conversion space for storing the conversion unit, a detection space for storing the detection unit, and a flow path space for storing a specific portion of the flow path member. The flow path space, the conversion space, and / or the detection space may be separated by a partition wall that restricts ventilation.

  When the flow path space in which the specific portion of the flow path member is disposed is divided by the conversion space or the detection space and the partition wall as in the second aspect, the air flow is restricted by the partition wall. Therefore (that is, ventilation is blocked or restricted), it is difficult for gas to flow from the conversion space or the detection space into the flow path space.

  Therefore, for example, the conversion unit of the conversion unit arranged in the conversion space and the detection unit of the detection unit arranged in the detection space are respectively heated by the heater, and the gas in the conversion space and the detection unit Even when the temperature of the gas rises, the gas whose temperature has risen is blocked by the partition walls, and thus hardly flows into the flow path space.

Therefore, since the temperature of the specific part of the flow path member arranged in the flow path space is hardly increased, the generation of reducing gas can be suppressed.
As described above, in the second aspect, the specific portion of the flow path member is not easily influenced by the temperature of the conversion space or the detection space as well as the temperature from the external environment. In addition to being able to be further suppressed, there is a remarkable effect that the durability of the gas sensor can be further improved.

  (3) In the third aspect of the present disclosure, the partition wall includes a first partition wall provided in one of the pair of containers and a second partition wall provided in the other container. In the abutting portion with the two partition walls, a recess provided at the tip of the first partition and a projection provided at the tip of the second partition may be fitted.

  In the case where the concave portion at the tip of the first partition wall of one container and the convex portion at the tip of the second partition wall of the other container are fitted as in the third aspect, Thus, since the gas flow path length is long, the gas is less likely to enter the flow path space from the conversion space or the detection space.

  Therefore, the specific portion of the flow path member is less susceptible to the temperature from the conversion space and the detection space, so that the decrease in measurement sensitivity of the gas sensor can be further suppressed, and the durability of the gas sensor can be further improved. Has a remarkable effect.

It is a side view which shows the structure of the opening side of a 2nd case by removing a 1st case among the housings of the breath sensor of 1st Embodiment. It is a disassembled perspective view which decomposes | disassembles and shows the breath sensor of 1st Embodiment. It is sectional drawing which shows the cross section (AA cross section of FIG. 1, FIG. 2) which fractured | ruptured the housing of the breath sensor of 1st Embodiment. (A) is sectional drawing which shows the cross section which looked at the fitting part of the housing of the exhalation sensor of 1st Embodiment from the Z direction perpendicular | vertical to the X direction and Y direction of FIG. 3, (b) is the exhalation of 2nd Embodiment. It is sectional drawing which shows the fitting part (section of the position similar to Fig.4 (a)) of the housing of a sensor. It is explanatory drawing which shows structures, such as a conversion unit and a detection unit. It is sectional drawing which fractures | ruptures and shows the breath sensor of 3rd Embodiment along ZX plane.

Hereinafter, an embodiment of a gas sensor to which the present disclosure is applied will be described with reference to the drawings.
[1. First Embodiment]
In the first embodiment, as an example, an exhalation sensor that detects the concentration of a specific gas component in exhalation will be described as a gas sensor.

  This exhalation sensor is used, for example, for the purpose of measuring an extremely low concentration (for example, several ppb to several hundred ppb level) of NOx (for example, NO) in the expiratory gas G (that is, the gas to be measured G) for asthma diagnosis. It is a sensor.

[1-1. Configuration of exhalation sensor]
First, the overall configuration of the breath sensor 1 will be described.
As shown in FIGS. 1 and 2, the breath sensor 1 of the first embodiment includes a conversion unit 5, a detection unit 7, and a flow path member 9 inside a housing 3.

Each configuration will be described below.
<Housing configuration>
As shown in FIG. 1, the housing 3 is a housing having an outer shape in which boxes having different sizes are stacked in two stages, and is made of, for example, a resin made of polyphenylene sulfide (PPS).

  That is, the outer shape of the housing 3 is a rectangular shape in a plan view (when viewed from above in FIG. 1), and a rectangular parallelepiped lower box 3a constituting the lower part and a rectangular parallelepiped upper box constituting the upper part. 3b has a shape that is superposed vertically. In addition, the dimension of the left-right direction of FIG. 1 of the upper box 3b is shorter than the lower box 3a.

  In addition, a cylindrical lower cassette connector 13 is disposed on the side wall (lower front end side wall) 11 on the front end side of the lower box 3a so as to penetrate the lower front end side wall 11. Similarly, a cylindrical upper cassette connector 17 is disposed on the side wall (upper front end side wall) 15 on the front end side of the upper box 3b so as to penetrate the upper front end side wall 15. A plurality of lead wires 19 are inserted through the lower cassette connector 13 and the upper cassette connector 17, respectively.

  As shown in FIG. 2, the housing 3 described above includes a first case 21 and a second case 23 that are integrally combined as will be described in detail later. That is, the housing 3 is configured by integrally assembling the first case 21 and the second case 23 with the five screws 25.

The housing 3 includes a conversion space 29, a detection space 31, and a flow path space 33 inside itself (that is, the internal space 27).
The conversion unit 5 is disposed in the conversion space 29, the detection unit 7 is disposed in the detection space 31, and the flow path member 9 is disposed in the flow path space 33.

  Specifically, the interior of the housing 3 is provided with a horizontal partition wall 35 that divides the internal space 27 into upper and lower parts in FIG. 1 so as to extend along the XY plane. The horizontal partition 35 divides the upper detection space 31 in FIG. 1 from the lower conversion space 29 and flow path space 33 in FIG. 1.

  Further, the conversion space 29 and the flow path space 33 are separated by a vertical partition wall 37 provided perpendicular to the horizontal partition wall 35. That is, the vertical partition wall 37 is provided so as to extend from the central portion of the horizontal partition wall 35 in the left-right direction in FIG. 1 toward the lower side in FIG. 1 (that is, along the ZY plane).

  In the following description, the portion of the horizontal partition wall 35 on the left side (front end side) in FIG. 1 from the vertical partition wall 37 is referred to as a first horizontal partition wall 39, and the portion on the right side (rear end side) in FIG. This is referred to as a second horizontal partition wall 41.

  The second horizontal partition wall 41 is formed with a first through hole 43 through which the flow path member 9 is inserted, but between the inner peripheral surface of the first through hole 43 and the outer peripheral surface of the flow path member 9. Since there is only a slight interval, there is almost no ventilation between the detection space 31 and the flow path space 33.

  Similarly, the vertical partition wall 37 is formed with a second through hole 45 through which the flow channel member 9 is inserted, but between the inner peripheral surface of the second through hole 45 and the outer peripheral surface of the flow channel member 9. Since there is only a slight gap, there is almost no ventilation between the conversion space 29 and the flow path space 33.

<Internal configuration of housing>
As shown in FIG. 1, the lower cassette connector 13 is connected to the conversion unit 5. The lower cassette connector 13 is configured to be connectable to an external device (not shown) via a lead wire 19a and a connection connector 51a.

  As will be described later, the conversion unit 5 includes a first heater 53 (see FIG. 5) that generates heat when energized. Heater power to the first heater 53 is supplied from the external device to the first heater 53 via the connection connector 51a, the lead wire 19a, and the lower cassette connector 13.

  On the other hand, the upper cassette connector 17 is connected to the detection unit 7. The upper cassette connector 17 is configured to be connectable to an external device (not shown) via the lead wire 19b and the connection connector 51b.

  As will be described later, the detection unit 7 includes a second heater 55 (see FIG. 5) that generates heat when energized. Heater power to the second heater 55 is supplied from the external device to the second heater 55 via the connection connector 51b, the lead wire 19b, and the upper cassette connector 17.

  The detection signal output from the detection unit 7 is output from the upper cassette connector 17 to an external device via the lead wire 19b (however, a lead wire different from that for the second heater 55) and the connection connector 51b.

  As shown in FIG. 2, the conversion unit 5 includes an introduction pipe 57 for introducing exhaled air (G) from the outside, and a discharge pipe 59 for discharging the exhaled gas after conversion (that is, the gas after passage). ing. On the other hand, the detection unit 7 includes an introduction pipe 61 (see FIG. 1) for introducing the exhaled breath after conversion, and a discharge pipe 63 for discharging the exhaled breath after the detection.

The introduction pipes 57 and 61 and the discharge pipes 59 and 63 are each made of a metal material (for example, stainless steel).
Then, as shown in FIG. 2, exhaled air is introduced into the conversion unit 5 through the auxiliary pipes 65, 67, 69 and the introduction pipe 57, and after exiting the conversion unit 5, the flow path member which is a gas flow pipe 9 is introduced into the detection unit 7. After the specific component in the expiration is detected by the detection unit 7, the expiration is discharged to the outside through the auxiliary pipe 71 connected to the discharge pipe 63 of the detection unit 7.

  Since the entire flow path member 9 is a tube formed of a polymer material (fluorine rubber, fluoroelastomer, etc.) containing fluorine, the entire flow path member 9 is a specific portion. This polymer material has a characteristic of generating a reducing gas (for example, an organic compound gas such as benzaldehyde) by receiving heat.

  Further, as shown in FIGS. 1 and 2, the breath sensor 1 includes a first heat insulating material 73, a second heat insulating material 75, and a third heat insulating material 77 inside the housing 3. The 1st heat insulating material 73, the 2nd heat insulating material 75, and the 3rd heat insulating material 77 are comprised, for example using glass fiber.

  The first heat insulating material 73 and the second heat insulating material 75 are disposed in the conversion space 29. The first heat insulating material 73 has a shape that is disposed on the upper side, the lateral side, and the lower side of the conversion unit 5, and is provided to insulate the conversion unit 5 and the housing 3. The second heat insulating material 75 has a plate shape and is disposed below the first heat insulating material 73. The third heat insulating material 77 is disposed in the detection space 31. The third heat insulating material 77 has a plate shape, is disposed below the detection unit 7, and is provided to insulate the detection unit 7 and the conversion space 29.

[1-2. Configuration of fitting portions of first and second cases]
Next, the fitting part in which the first case 21 and the second case 23 are fitted in the configuration of the housing 3 will be described in detail.

As shown in the AA cross section of FIG. 2 in FIG. 3, the housing 3 includes a first case 21 and a second case 23 that are integrally combined from above and below in FIG. 3.
That is, the housing 3 is fitted at the fitting portion 85 so that the opening 81 of the first case 21 and the opening 83 of the second case 23 face each other and the inner space 27 is provided inside the housing 3. These are integrated into one unit.

Below, the structure of this fitting part 85 is demonstrated in detail.
Of the first end 87 on the opening side (the upper side in FIG. 3) of the first case 21, that is, the first outer wall 89 constituting the first case 21, the first end 87, which is the tip portion on the second case 23 side. As shown in an enlarged view in FIG. 4A, a first recess 93 is formed which is recessed on the bottom 91 side (lower side in FIG. 3) of the first case 21.

  The first concave portion 93 is formed such that the inner side of the first outer wall 89 (on the left inner space 27 side in FIG. 4) is recessed toward the bottom 91 side of the first case 21 from the outer side (the outer world side on the right side in FIG. 4). It is. Therefore, the 1st convex part 95 which protrudes on the outer side of the 1st recessed part 93 at the bottom part 95 side (upper side of FIG. 3) of the 2nd case 23 is comprised.

The first concave portion 93 and the first convex portion 95 are formed over substantially the entire circumference of the first end portion 87 on the opening side of the first case 21.
On the other hand, the second end 97 on the opening side (the lower side in FIG. 3) of the second case 23, that is, the second outer wall 99 constituting the second case 23, the second portion which is the tip portion on the first case 21 side. As shown in an enlarged view in FIG. 4A, the end portion 97 is formed with a second convex portion 101 that protrudes toward the first concave portion 93.

  As for this 2nd convex part 101, the inner side (the inner space 27 side of the left side of FIG. 4) of the 2nd outer wall 99 protruded to the bottom part 91 side of the 1st case 21 from the outer side (the external field side of the right side of FIG. 4). Is. Therefore, a second concave portion 103 is formed outside the second convex portion 101 and is recessed toward the bottom 95 side (the upper side in FIG. 3) of the second case 23.

The second convex portion 101 and the second concave portion 103 are formed over substantially the entire circumference of the second end portion 97 on the opening side of the second case 23.
Therefore, when the first case 21 and the second case 23 are combined together in the vertical direction of FIG. 3, the first recessed portion 93 of the first case 21 and the second case 23 of the second case 23 are combined in the fitting portion 85. The convex portion 101 is fitted and abutted, and the first convex portion 95 of the first case 21 and the second concave portion 103 of the second case 23 are fitted and abutted.

  By fitting in this way, the cross section of the abutting portion is bent into a crank shape, as shown in FIG. 4A, and the gas flow path length is longer than when no fitting portion 85 is provided. And the airtightness inside the housing 3 is improved.

Moreover, the fitting part 85 as described above is configured similarly in the vertical partition wall 37.
Specifically, as shown in FIG. 3, the vertical partition 37 includes a first vertical partition 105 extending from the bottom 91 of the first case 21 toward the bottom 95 of the second case 23, and a first case from the bottom 95 of the second case. 21 and a second vertical partition wall 107 extending to the bottom 91 side.

And the front-end | tip part of the 1st vertical partition 105 and the front-end | tip part of the 2nd vertical partition 107 become the fitting part 109 fitted similarly to the said fitting part 85. FIG.
That is, a concave portion 105a and a convex portion 105b similar to those of the first case 21 are provided at the tip of the first vertical partition wall 105, and a convex portion 107a and a concave portion 107b similar to those of the second case 23 are provided at the tip of the second vertical partition wall 107. And are provided. And the recessed part 105a of the 1st vertical partition 105 and the convex part 107a of the 2nd vertical partition 107 fit, and the convex part 105b of the 1st vertical partition 105 and the recessed part 107b of the 2nd vertical partition 107 fit. ing.

[1-3. Configuration of conversion unit and detection unit]
Next, the structure of the conversion unit 5 and the detection unit 7 is demonstrated based on FIG.
<Conversion unit>
As schematically shown in FIG. 5, the conversion unit 5 is accommodated in the internal space (that is, the first chamber C1), the first casing unit 111 surrounding the first chamber C1, and the first casing unit 111. Partition wall 113. The first chamber C1 is divided (ie, separated) into a first chamber R1 on the left side in FIG. 5 and a second chamber R2 on the right side in FIG.

  An introduction pipe 57 is connected to the left side surface of the first housing part 111, and a discharge pipe 59 is connected to the right side surface of the first housing part 111. The introduction pipe 57 communicates with the first chamber R1 of the first chamber C1, and the discharge pipe 59 communicates with the second chamber R2 of the first chamber C1.

A first heater 53 is disposed at the center of the partition wall 113 (the center in the left-right direction in FIG. 5), and a catalyst constituting the conversion unit 115 is disposed at the left and right of the first heater 53. As will be described later, the conversion unit 115 configured by this catalyst is a structure that functions to convert a first gas component (eg, NO) contained in exhaled breath into a second gas component (eg, NO ₂ ).

  The first heater 53 heats the catalyst to an operating temperature (that is, a temperature at which the function is exerted) by heating by energization from a battery (not shown), and is made of a heating resistor such as platinum.

  A gas flow path 117 extending from the first chamber R1 to the second chamber R2 is formed inside the conversion unit 115. That is, the gas flow path 117 configured to be bent at a plurality of locations is formed in the conversion unit 115 so that the exhaled air contacts as much as possible on the surface of the catalyst.

  In this conversion unit 5, the exhaled gas (G) introduced from the introduction pipe 57 into the first chamber R1 of the first chamber C1 contacts (that is, passes through) the conversion unit 115 as shown by the arrow in FIG. ) After the gas component is converted, it is discharged from the discharge pipe 59 to the flow path member 9.

<Detection unit>
As shown in FIG. 5, the detection unit 7 includes an internal space (that is, the second chamber C <b> 2), a second housing portion 121 that surrounds the second chamber C <b> 2, and an element portion that is accommodated in the second housing portion 121. 123. This element part 123 is suspended and held by the holding part 125 in the second chamber C2.

  The element unit 123 has a plate shape, and includes a base unit 127, a detection unit 129 disposed on the upper surface of the base unit 127 (upward in FIG. 5), and a second heater 55 disposed on the lower surface of the base unit 127. I have. That is, the element unit 123 has a stacked structure in which the detection unit 129, the base unit 127, and the second heater 55 are stacked together.

Among these, the detection unit 129 has a mixed potential type sensor structure as will be described later, and its electrical characteristics change according to the concentration of the second gas component (for example, NO ₂ ). The base portion 127 is a ceramic substrate made of, for example, alumina having electrical insulation. The second heater 55 heats the detection unit 129 to the operating temperature by heating by energization from the battery, and is made of a heating resistor such as platinum.

  An introduction pipe 61 is connected to the right side surface of the second housing part 121 in FIG. 5, and a discharge pipe 63 is connected to the left side surface of the second housing part 121. The introduction pipe 61 and the discharge pipe 63 communicate with the second chamber C2.

  As shown in FIG. 5, one end of the flow path member 9 is connected to the discharge pipe 59 of the first chamber C1, and the other end of the flow path member 9 is connected to the introduction pipe 61 of the second chamber C2. In other words, the second chamber R2 of the first chamber C1 and the second chamber C2 communicate with each other so that the flow (G) can be circulated by the flow path member 9.

[1-4. Operational principle of exhalation sensor]
Next, the operation principle of the breath sensor 1 will be described. Since it is a known technique as described above, it will be briefly described.

The converter 115 is made of, for example, a catalyst made of zeolite carrying Pt, and a gas flow path 117 is provided inside so that exhaled air can pass. This catalyst converts a first gas component (for example, NO) contained in exhaled breath into a second gas component (for example, NO ₂ ) at a predetermined ratio at a predetermined activation temperature that is an operating temperature. .

Note that the catalyst of the converter 115 oxidizes reducing gas (CO and the like) in exhaled air in addition to NO, so that the amount (and hence the concentration) of reducing gas is reduced.
The detection unit 129 is configured as a known mixed potential sensor element using a solid electrolyte body and a pair of electrodes disposed on the surface of the solid electrolyte body.

For example, the detection unit 129, a solid electrolyte on the body made of YSZ, can be employed, such as a sensor element disposed an electrode made of the electrode and WO ₃ consisting of Pt.
The detection unit 129 has an electrical characteristic (that is, a starting point) according to the concentration of the second gas component (for example, NO ₂ ) contained in exhaled air at an activation temperature that is an operating temperature different from the activation temperature of the catalyst. The power) changes.

  In addition, the detection unit 129 changes (that is, decreases) the electrical characteristics (that is, electromotive force) when a reducing gas other than NO in exhaled gas (such as CO) is oxidized and reduced in the conversion unit 115. ), The sensitivity is lowered.

  The second heater 55 can heat the detection unit 129 to the high temperature described above. On the other hand, the first heater 53 can change the temperature of the conversion unit 115 to a temperature different from that of the detection unit 129.

Therefore, the expiration sensor 1 can detect the concentration of NOx (NO), which is a specific gas component in expiration, in the following manner.
As shown in FIG. 5, exhaled air is first introduced from the introduction tube 57 into the first chamber R1 of the first chamber C1. Conversion unit 115, the first heater 53, because it is heated to a predetermined activation temperature, NO in exhaled air is converted to NO _2.

The exhaled air after the conversion is discharged from the second chamber R2 of the first chamber C1 to the flow path member 9 through the discharge pipe 59 and is introduced into the second chamber C2 through the introduction pipe 61.
Next, expiration of the converted is in contact with the detection unit 129 in the second chamber C2, depending on the concentration of NO _2, the potential difference (electromotive force) is generated between a pair of electrodes, NO ₂ A sensor signal corresponding to the concentration of gas is output from the breath sensor 1 to an external device. Based on the sensor signal output from the expiration sensor 1, the concentration of NOx, which is a specific gas component in expiration, can be detected by an external device.

[1-5. effect]
(1) In the breath sensor 1 of the first embodiment, the first recess 21 and the first protrusion 95 are provided in the opening 87 of the first case 21, and the opening of the second case 23 is the end. A second convex portion 101 and a second concave portion 103 are provided at 97.

  And while the 1st recessed part 93 of the 1st case 21 and the 2nd convex part 101 of the 2nd case 23 fit, the 1st convex part 95 of the 1st case 21 and the 2nd recessed part 103 of the 2nd case 23, Is configured to fit.

  Therefore, in the fitting portion 85 where the first case 21 and the second case 23 are fitted, compared to the case where the first case 21 and the second case 23 are simply in contact with each other from a flat surface, the external part is It is difficult for gas such as air to flow in. That is, the gas flow path length of the fitting part 85 is increased as compared with the non-fitting part.

  For this reason, even when the outside air temperature is high, for example, air having a high temperature hardly enters the inside of the housing 3. As a result, for example, even if the outside air temperature becomes high, the temperature in the housing 3 is unlikely to rise, so the temperature of the flow path member 9 (specifically, a specific portion made of fluororubber or the like) is unlikely to rise. Therefore, it can suppress that reducing gas generate | occur | produces from the specific part of the flow-path member 9. FIG.

  That is, in the first embodiment, since the housing 3 has a structure that suppresses the entry of outside air such as air from the outside of the housing 3, the specific portion of the flow path member 9 in the housing 3 The generation state of the reducing gas generated from the specific portion can be stabilized. Therefore, there is a remarkable effect that the measurement sensitivity of the breath sensor 1 can be stabilized.

  Further, when reducing gas is excessively generated from a specific portion, sufficient measurement sensitivity cannot be obtained when the breath sensor 1 is used. However, in the first embodiment, a temperature change of the external environment is received. Since it is difficult, it can suppress that reducing gas generate | occur | produces excessively from a specific part. Therefore, the durability of the breath sensor 1 can be improved. That is, the life of the breath sensor 1 can be extended.

  As described above, according to the first embodiment, the influence of the temperature from the outside on the breath sensor 1 can be reduced, the decrease in measurement sensitivity of the breath sensor 1 can be suppressed, and the durability of the breath sensor 1 can be improved. Has an effect.

  (2) In the first embodiment, the conversion space 29 for storing the conversion unit 5, the detection space 31 for storing the detection unit 7, and the flow path member 9 (specifically, a specific portion) are housed in the housing 3. And a flow path space 33 to be accommodated.

  The flow path space 33 and the conversion space 29 are separated by a vertical partition wall 37 and the ventilation is restricted. The flow path space 33 and the detection space 31 have a horizontal partition wall 35 (specifically, a second partition wall in detail). The ventilation is restricted by being divided by the horizontal partition wall 41).

  Therefore, for example, the conversion unit 115 of the conversion unit 5 disposed in the conversion space 29 is heated by the first heater 53, and the detection unit 129 of the detection unit 7 disposed in the detection space 31 is the second heater 55. Even when the temperature of the gas in the conversion space 29 or the gas in the detection space 31 rises due to heating by the gas, the gas whose temperature has risen is blocked by the horizontal partition walls 35 and the vertical partition walls 37, It is difficult to flow into the use space 33.

Therefore, since the temperature of the specific part of the flow path member 9 disposed in the flow path space 33 is hardly increased, the generation of reducing gas can be suppressed.
As described above, in the first embodiment, the specific portion of the flow path member 9 is not easily influenced by the temperature of the conversion space 29 and the detection space 31 as well as the temperature from the external environment. As a result, it is possible to further suppress the decrease in the measurement sensitivity and to further improve the durability of the breath sensor 1.

  (3) In the first embodiment, a concave portion 105a and a convex portion 105b similar to the first case 21 are provided at the tip of the first vertical partition wall 105, and the second case 23 and the tip of the second vertical partition wall 107 are provided. Similar convex portions 107a and concave portions 107b are provided.

  And the recessed part 105a of the 1st vertical partition 105 and the convex part 107a of the 2nd vertical partition 107 fit, and the convex part 105b of the 1st vertical partition 105 and the recessed part 107b of the 2nd vertical partition 107 fit. ing.

  Since the gas flow path length is long in the fitting portion 109 in the vertical partition wall 37 as described above, the gas is less likely to enter the flow path space 33 from the conversion space 29 and the detection space 31.

  Therefore, the specific portion of the flow path member 9 is less susceptible to the temperature from the conversion space 29 and the detection space 31, so that it is possible to further suppress the decrease in measurement sensitivity of the breath sensor 1 and to improve the durability of the breath sensor 1. There is a remarkable effect that the sex can be further improved.

[1-6. Correspondence of wording]
Here, the correspondence between words will be described.
Conversion unit 115, conversion unit 5, detection unit 129, detection unit 7, flow path member 9, housing 3, breath sensor 1, first case 21 and second case 23, internal space 27, first space of the first embodiment. The first concave portion 93, the second convex portion 101, the conversion space 29, the detection space 31, the flow path space 33, the vertical partition wall 37, and the second horizontal partition wall 41 are respectively the conversion unit, the conversion unit, and the detection of the present disclosure. Part, detection unit, flow path member, housing, gas sensor, multiple containers, hollow, concave part, convex part, conversion space, detection space, flow path space, and partition wall.

[2. Second Embodiment]
Next, the second embodiment will be described, but the description of the same configuration as the first embodiment will be omitted or simplified. In addition, the same number is attached | subjected to the structure similar to 1st Embodiment.

In the second embodiment, a configuration for increasing the gas flow path length as shown in FIG. 4B can be employed as the configuration of the fitting portion 85 of the first embodiment.
That is, in the second embodiment, the front end portion (end portion) 87 of the outer wall 89 of the first case 21 is provided with the recess 131 having a recessed center, and the front end portion (end portion) 97 of the outer wall 99 of the second case 23. In addition, a projection 133 whose center protrudes is provided.

Thereby, the fitting part 135 which the convex part 133 of the 2nd case 23 fits in the recessed part 131 of the 1st case 21 can be comprised.
The second embodiment has the same effects as the first embodiment. In the second embodiment, since the gas flow path length in the fitting portion 135 is longer than that in the first embodiment, the flow path member 9 has an advantage that it is less susceptible to the external temperature.

[3. Third Embodiment]
Next, the third embodiment will be described, but the description of the same configuration as the first embodiment will be omitted or simplified. In addition, the same number is attached | subjected to the structure similar to 1st Embodiment.

The breath sensor 141 according to the third embodiment basically has the same configuration as that of the first embodiment.
That is, the conversion unit 5, the detection unit 7, the flow path member 9, and the like are accommodated in the housing 3.

In addition, the space in which the conversion unit 5 and the flow path member 9 are arranged is separated from the space in which the detection unit 7 is arranged (that is, the detection space 31) by the horizontal partition wall 35.
However, in the third embodiment, the space in which the conversion unit 5 is disposed and the space in which the flow path member 9 is disposed are not separated by the vertical partition walls 37 as in the first embodiment, and are integrated spaces. 143.

The third embodiment has the same effects as the first embodiment. Further, according to the third embodiment, there is an advantage that the configuration can be simplified and the weight can be reduced.
In addition, it is not necessary to provide the 2nd horizontal partition 41 among the horizontal partitions 35. FIG. Alternatively, both the vertical partition wall 37 and the second horizontal partition wall 41 may not be provided.
[4. Other Embodiments]
Needless to say, the present disclosure is not limited to the above-described embodiment, and can be implemented in various forms without departing from the present disclosure.

(1) For example, the shape of the container that accommodates the breath sensor (particularly the shape of the fitting portion) is not particularly limited as long as the function of the present disclosure is exhibited in addition to the configuration of each of the embodiments.
(2) The conversion unit and the detection unit are not particularly limited as long as the functions of the present disclosure are exhibited in addition to the configuration of the embodiment.

(3) As the detector, various detectors whose electrical characteristics (for example, resistance value, electromotive force, etc.) change according to the concentration of the specific gas component in the second chamber can be adopted.
(4) As a material of the gas communication pipe, various materials that generate reducing gas by receiving heat can be adopted.

(5) The reducing gas generated from the gas communication pipe includes, for example, an organic compound gas such as benzaldehyde.
(6) The present disclosure can be applied to, for example, a gas leak detection sensor in addition to the breath sensor.

  (7) Note that the functions of one component in each of the above embodiments may be distributed as a plurality of components, or the functions of a plurality of components may be integrated into one component. Moreover, you may abbreviate | omit a part of structure of each said embodiment. In addition, at least a part of the configuration of each of the above embodiments may be added to or replaced with the configuration of each of the above other embodiments. In addition, all the aspects included in the technical idea specified from the wording described in the claims are embodiments of the present disclosure.

DESCRIPTION OF SYMBOLS 1,141 ... Breath sensor 3 ... Housing 5 ... Conversion unit 7 ... Detection unit 9 ... Flow path member 21 ... 1st case 23 ... 2nd case 27 ... Internal space 29 ... Conversion space 31 ... Detection space 33 ... Flow path Space 37 ... Vertical partition wall 39 ... First horizontal partition wall 41 ... Second horizontal partition wall 93, 105a, 107b, 131 ... Concave portion 101, 105b, 107a, 133 ... Convex portion 105 ... First partition wall 107 ... Second partition wall 115 ... Conversion Part 129 ... detection

Claims (3)

A conversion unit having a conversion unit for converting the first gas component in the gas to be measured into the second gas component;
A detection unit having a detection unit that contacts a post-passage gas that is the measurement gas that has passed through the conversion unit, and whose electrical characteristics change according to the concentration of the second gas component in the measurement gas;
A flow path member constituting a gas flow path of the post-passage gas between the conversion unit and the detection unit;
A housing that houses the conversion unit, the detection unit, and the flow path member;
A gas sensor comprising:
The flow path member includes a specific portion made of a material that is capable of generating a reducing gas that is different from the first gas component and the second gas component and has a reducing property by receiving heat,
The housing is configured integrally so that each opening side of a plurality of containers face each other and has a hollow inside,
Among the plurality of containers, in the pair of containers having the facing openings, a concave portion is provided at an end portion on the opening side of one container, and a convex portion is provided at an end portion on the opening side of the other container. And the convex portion are fitted together so that the pair of containers are integrally formed.
Gas sensor. The housing includes a conversion space for storing the conversion unit, a detection space for storing the detection unit, and a flow path space for storing the specific portion of the flow path member.
The flow path space and the conversion space and / or the detection space are separated by a partition wall that restricts ventilation.
The gas sensor according to claim 1. The partition is composed of a first partition provided in one of the pair of containers and a second partition provided in the other container,
At the contact portion between the first partition and the second partition, a recess provided at the tip of the first partition and a projection provided at the tip of the second partition are fitted,
The gas sensor according to claim 2.