JP4630133B2 - Gas sensor - Google Patents

Description

  The present invention relates to a gas sensor placed in a high humidity environment.

  In general, a solid polymer membrane fuel cell is formed by sandwiching both sides of a solid polymer electrolyte membrane between a fuel electrode and an oxygen electrode to form a single cell, and a plurality of single cells are stacked to form one fuel cell stack. Yes. The fuel electrode is supplied with hydrogen as a fuel, the oxygen electrode is supplied with air as an oxidant, and hydrogen ions generated by a catalytic reaction at the fuel electrode pass through the solid polymer electrolyte membrane and pass through the oxygen electrode. The hydrogen ions and oxygen cause an electrochemical reaction to generate electricity.

  In such a solid polymer membrane fuel cell, conventionally, a hydrogen detector (gas sensor) is provided in the discharge system on the oxygen electrode side of the fuel cell, and the hydrogen on the fuel electrode side is removed from the solid polymer electrolyte membrane by this hydrogen detector. There is known a technique for detecting leakage to the oxygen electrode side through (see Patent Document 1). Specifically, in this technology, one hydrogen intake port (gas flow part) provided in the hydrogen detector is directed downward in the vertical direction, and the hydrogen detector is provided on the upper wall of the exhaust pipe. Thus, hydrogen having a light specific gravity can be satisfactorily taken into the hydrogen detector. In addition, in such a technology, by providing a water repellent filter at the hydrogen intake port, water droplets in the gas are removed by the water repellent filter before high-humidity gas enters the hydrogen detector to detect hydrogen. It is also considered to prevent water droplets from adhering to the detection element in the vessel.

JP2003-294675A (paragraphs 0008 to 0010, FIG. 4)

  However, in the above-described technique, since only one hydrogen intake port is provided, there is a possibility that gas taken into the hydrogen detector from the hydrogen intake port may stay inside, and in this case In this case, it is difficult to take in a new gas, and the detection performance may be deteriorated. In addition, in a state where the water vapor contained in the high-humidity gas has not yet become water droplets, the water vapor passes through the water-repellent filter. When the temperature is lowered, the water vapor is liquefied and the liquefied water accumulates on the water repellent filter. If water accumulates on the water-repellent filter in this way, the water-repellent filter is clogged, so that it is difficult for gas to be taken into the hydrogen detector thereafter, which may affect sensing.

  Therefore, in the present invention, while suppressing the decrease in the amount of gas taken in due to clogging of the gas flow portion configured to actively take in only the gas while suppressing the ingress of water by a water repellent filter or the like, It is an object of the present invention to provide a gas sensor that can suppress stagnation of taken-in gas.

As means for solving the above problems, the present invention comprises a gas detection element for detecting hydrogen contained in off-gas discharged from a fuel cell, a peripheral wall, and a bottom wall that is integral with the peripheral wall, a bottomed cylindrical element accommodating portion for accommodating the gas detection element, provided in the front Symbol bottom wall, said off-gas flowed through the are aligned along the flow direction of the off-gas into and out of the element receiving part comprising at least two gas through portion, the upper wall of the off-gas piping the off-gas flowing, the element receiving part is a gas sensor is mounted so as to protrude into the off-gas flow path, wherein each gas passage The portion includes a circular opening that is formed in the bottom wall and is larger than the gas detection element in plan view, and a water repellent filter provided in the opening , and in plan view, the gas detection element and the gas Established a flow-through section The obtained non said bottom wall portions are arranged to overlap, the gas detection element is provided with a detection element which is active against hydrogen, and a temperature compensation element is inert to hydrogen, In plan view, the first arrangement direction of the detection element and the temperature compensation element and the second arrangement direction of the at least two gas flow portions along the flow direction of the off gas are perpendicular to each other, and The first center of the detection element and the temperature compensation element overlaps the second center of the at least two gas flow portions, and a first imaginary line passing through the detection element and the temperature compensation element, the second virtual line passing through the respective centers of the at least two gas through section lying along the flow direction of the offgas, a gas sensor characterized that you intersect at cross.

According to such a gas sensor , since at least two gas flow portions are provided in the element housing portion of the gas sensor, for example, when the two gas flow portions are provided with a water repellent filter, Even if the flow passage portion is clogged, gas (gas) can be taken in from the remaining gas flow passage portion. That is, as compared with the conventional case, an extra gas flow part is provided, so that a decrease in the amount of gas taken in due to clogging of the gas flow part can be suppressed. Further, since the gas taken into the element housing portion is discharged to the outside from one of the at least two gas flow portions, it is possible to suppress the gas from staying in the element housing portion.

Also, in the gas sensor, the gas detecting element is preferably provided with a coil of metal wire containing platinum.
In the gas sensor, the gas detection element preferably includes a carrier that covers the coil and carries a catalyst.

According to the present invention, since at least two gas flow portions are provided in the element housing portion of the gas sensor, a decrease in the amount of gas taken in due to clogging of the gas flow portion is suppressed, and a retention of the taken-in gas is suppressed. can do.

[First Embodiment]
Next, embodiments of the present invention will be described in detail with reference to the drawings as appropriate. In the drawings to be referred to, FIG. 1 is a schematic configuration diagram showing a fuel cell system provided with a hydrogen sensor according to the first embodiment.

  As shown in FIG. 1, a hydrogen sensor (gas sensor) 1 according to the first embodiment is incorporated in a fuel cell system S in order to detect hydrogen in air off-gas discharged from the fuel cell 2. . Hereinafter, the fuel cell system S will be briefly described, and then the details of the hydrogen sensor 1 will be described.

The fuel cell system S mainly includes a fuel cell 2, an inlet side pipe 3 and an outlet side pipe 5 on the fuel electrode (anode) side, and an inlet side pipe 4 and an outlet side pipe 6 on the oxygen electrode (cathode) side. Yes.
The fuel cell 2 includes a single cell (not shown) in which an electrolyte membrane electrode structure in which a solid polymer electrolyte membrane made of, for example, a cation exchange membrane is sandwiched between a fuel electrode and an oxygen electrode is further sandwiched between a pair of separators. It consists of a stack composed of a large number of sets.

In this fuel cell 2, for example, hydrogen is supplied to the fuel electrode as a fuel via a fuel supply side inlet side pipe 3 from a hydrogen supply device (not shown) including a high-pressure hydrogen tank or the like, and an oxygen electrode is supplied by a compressor 21. Air is supplied to the oxygen electrode as an oxidant through the side inlet side pipe 4. On the catalyst electrode of the fuel electrode, hydrogen is ionized by the catalytic reaction, and the generated hydrogen ion passes through the appropriately polymerized solid polymer electrolyte membrane and moves to the oxygen electrode. Then, electrons generated during this period are taken out to an external circuit and used as direct current electric energy. Since oxygen-containing air is supplied to the oxygen electrode, hydrogen ions, electrons, and oxygen react electrochemically by the action of the catalyst of the oxygen electrode to generate water. .
Then, so-called off-gas containing unreacted reaction gas (for example, hydrogen or air) is discharged from the outlet side pipe 5 on the fuel electrode side and the outlet side pipe (flow channel) 6 on the oxygen electrode side.

Here, the hydrogen off-gas (anode off-gas) containing unreacted hydrogen is discharged from the outlet side pipe 5 on the fuel electrode side of the fuel cell 2 to the hydrogen circulation path 22, and the inlet side pipe on the fuel electrode side via the ejector 23. 3 is supplied to the fuel electrode of the fuel cell 2 again.
On the other hand, the air off gas (cathode off gas) containing a large amount of moisture in the reacted air is discharged to the atmosphere through the diluter 26 and the outlet side pipe 6.

Further, a hydrogen discharge path 25 is connected to the outlet side pipe 5 on the fuel electrode side of the fuel cell 2 via a purge valve 24, and a diluter 26 is connected to the hydrogen discharge path 25. The hydrogen off-gas can be discharged to the hydrogen discharge path 25 via the purge valve 24 and can be introduced to the diluter 26 through the hydrogen discharge path 25.
The diluter 26 is configured to dilute the hydrogen off gas taken from the hydrogen discharge passage 25 with an appropriate magnification by the air off gas discharged from the fuel cell 2 and discharge it as a diluted gas.
A gas catalytic combustion type hydrogen sensor 1 is disposed downstream of the diluter 26, and the hydrogen concentration of the diluted gas is monitored by this. Here, the hydrogen sensor 1 is arranged at the upper part in the vertical direction of the outlet side pipe 6 arranged so that the flow direction of the air off gas is the horizontal direction.

  Next, details of the hydrogen sensor 1 will be described with reference to FIGS. 2 and 3. In the drawings to be referred to, FIG. 2 is a cross-sectional view showing the inside of the hydrogen sensor according to the first embodiment, and FIG. 3 is a cross-sectional view along line AA in FIG. It is B sectional drawing (b).

  As shown in FIG. 2, the hydrogen sensor 1 includes a rectangular parallelepiped case 30 containing a control board (not shown). The case 30 is made of, for example, polyphenylene sulfide, and includes flange portions 31 at both ends in the longitudinal direction. A collar 32 is attached to the flange portion 31, and a bolt 33 is inserted into the collar 32, so that the flange portion 31 is attached to an outlet seat (flow path) 6 on the oxygen electrode side. (Wall) It is fastened and fixed to 6a.

  The lower end surface of the case 30 is provided with a gas detection element 50 and a heater 60 connected to the control board, and a bottomed cylindrical element receiving portion 34 for receiving these protrudes downward. It is provided as follows.

  The gas detection element 50 detects hydrogen (detected gas) contained in the dilution gas (gas). Specifically, as shown in FIG. 3A, the detection element 51 and the temperature compensation element 52 and a pair. The detection element 51 is a well-known element, and is formed by coating a coil of metal wire containing platinum or the like having a high temperature coefficient with respect to electric resistance with a carrier such as alumina carrying a catalyst. The catalyst is made of a noble metal active against hydrogen. The temperature compensation element 52 is inactive with respect to hydrogen, and is formed, for example, by coating the surface of a coil equivalent to the detection element 51 with a carrier such as alumina.

  When the detection element 51 becomes hot due to the reaction heat generated when hydrogen comes into contact with the catalyst, a difference occurs in the resistance value between the detection element 51 and the temperature compensation element 52, so that the hydrogen concentration can be detected from this difference. It can be done. Note that the change in electrical resistance value due to the ambient temperature is offset by using the temperature compensation element 52.

  The heater 60 heats the inside of the element accommodating portion 34 (hereinafter, this internal space is also referred to as “gas detection chamber R”), thereby suppressing the occurrence of condensation in the gas detection element 50.

  As shown in FIG. 2, the element accommodating portion 34 is adapted to fit into a through hole 6 c formed in the outlet side pipe 6, and a part of the element accommodating part 34 protrudes from the inner surface 6 b of the outlet side pipe 6. It is comprised so that it may expose in the side piping 6 (henceforth, the exposed part is called "lower half part"). In the bottom wall 34c of the lower half portion of the element accommodating portion 34 exposed in the outlet side pipe 6 in this way, two gas flow portions 70 arranged in the dilute gas flow direction are provided.

  The gas flow part 70 includes a circular opening 71 formed in the bottom wall 34c of the element housing part 34 (see FIG. 3B), a water repellent filter 72 provided in the opening 71, and the water repellent. An explosion-proof filter 73 provided on the filter 72 is provided. Thereby, water contained in the wet dilution gas is repelled by the water repellent filter 72 so as not to enter the gas detection chamber R, and explosion-proof property is also ensured.

  A predetermined groove 34b is formed along the circumferential direction in the peripheral wall 34a of the upper half of the element housing portion 34, and a seal member 35 is provided in the groove 34b. Thereby, when the hydrogen sensor 1 is attached to the outlet side pipe 6, the seal member 35 is brought into close contact with the inner peripheral surface of the through hole 6 c of the outlet side pipe 6 and the groove 34 b of the element accommodating portion 34. Ensuring airtightness between.

Next, the operation of the hydrogen sensor 1 will be described.
As shown in FIG. 2, the dilution gas flowing in the outlet side pipe 6 is gas from at least one gas flow portion 70 of the two gas flow portions 70 formed on the bottom wall 31 c of the element housing portion 34. It is taken into the detection chamber R. The dilution gas taken into the gas detection chamber R stays slightly in the gas detection chamber R and then exits from at least one of the two gas flow sections 70.

  Further, when the dilution gas is taken into the gas detection chamber R from the gas flow part 70 and the internal temperature is lowered and a part of the water vapor of the dilution gas is liquefied, as shown in FIG. In addition, water droplets W are attached to the inner surface of the element housing portion 34. At this time, the water droplet W attached to the inner surface of the peripheral wall 34a of the element housing portion 34 flows downward due to the influence of gravity and adheres to the gas flow portion 70 of the bottom wall 34c. For example, even if water adheres to the entire surface of one of the two gas flow portions 70 and the gas flow portion 70 becomes completely clogged, the other gas flow portion 70 thereafter The dilution gas is satisfactorily taken into the element housing portion 34.

According to the above, the following effects can be obtained in the first embodiment.
Since the two gas flow portions 70 are provided in the element accommodating portion 34, it is possible to suppress a decrease in the amount of dilution gas taken in due to clogging of the gas flow portion 70 and to suppress the stagnation of the taken-in gas. In addition, since the clogging of the gas flow part 70 is suppressed in this way, the hydrogen detection accuracy can be improved, and the life of the hydrogen sensor 1 can be improved at low cost.

The present invention is not limited to the first embodiment, and can be implemented in various forms.
In the first embodiment, the two gas flow portions 70 are arranged on the bottom wall 34c of the element accommodating portion 34 so as to be aligned in the flow direction of the dilution gas. However, the present invention is not limited to this, and the gas flow portions 70 The position of the portion 70 may be provided at any position on the bottom wall 34c. Further, the size, shape, etc. of the two gas flow portions 70 are made different between one and the other so that one functions mainly for exclusive use of gas and the other functions mainly for exclusive use of gas discharge. You may do it.
In the first embodiment, the outer peripheral shape of the cross section of the element accommodating portion 34 is circular. However, the present invention is not limited to this, and may be any shape such as an elliptical shape or a polygonal shape. .

  In the first embodiment, the element accommodating portion 34 is protruded from the inner surface 6b of the outlet side pipe 6. However, when the gas flow passage 70 is provided on the bottom wall 34c of the element accommodating portion 34 as described above, the bottom wall It is desirable that the lower surface of 34 c be flush with the inner surface 6 b of the outlet side pipe 6. According to this, the element accommodating portion 34 does not become a resistance to the flow of the dilution gas, and the air off-gas flows smoothly, so that it is possible to suppress the energy consumption of the air supply.

First of reference form]
Below, the 1st reference form of this invention is demonstrated. Since this embodiment is obtained by changing the structure of the element housing portion of the first embodiment, the same components as those of the first embodiment are denoted by the same reference numerals, and the description thereof is omitted. In the drawings to be referred to, FIG. 4 is a cross-sectional view showing the inside of the hydrogen sensor according to the first reference embodiment, and FIG. 5 is a cross-sectional view taken along the line CC in FIG. It is D sectional drawing (b).

As shown in FIG. 4, the hydrogen sensor 1 ′ according to the first reference embodiment includes an element housing portion 34 ′ having a structure different from that of the first embodiment.
The element housing portion 34 ′ has the same shape and structure as the upper half portion of the element housing portion 34 of the first embodiment, while the upper half portion has two gas passages in the peripheral wall 34a of the lower half portion. It differs from 1st Embodiment by the point by which the flow part 70 is provided and the water drain hole 34d etc. in the bottom wall 34c.

  As shown in FIGS. 4 and 5, the two gas flow portions 70 are provided on the peripheral wall 34 a of the element housing portion 34 ′ so as to overlap each other when viewed from the flow direction of the dilution gas. Specifically, as shown in FIG. 5 (b), one gas flow portion 70 is provided at a substantially central portion of the front surface FF that is a portion directly exposed to the dilution gas in the peripheral wall 34a of the element accommodating portion 34 '. The other gas flow portion 70 is provided at the substantially central portion of the side back portion SB that is a portion that is not directly exposed to the dilution gas.

  Further, as shown in FIG. 4, a drain hole 34d for discharging the water liquefied in the gas detection chamber R to the outside is provided at an appropriate position on the bottom wall 34c of the element accommodating portion 34. 34d is provided with an explosion-proof filter 73 similar to that of the first embodiment, which is formed of a mesh capable of passing water. Furthermore, a drainage channel 36 is provided in the lower part of the drainage hole 34d, and the drainage hole 36 is formed so that the lower part of the drainage channel 36 is bent toward the downstream side in the flow direction of the dilution gas. The dilution gas is prevented from entering the gas detection chamber R from 34d. Incidentally, since the element housing part 34 protrudes from the inner surface 6b of the outlet side pipe 6, the cross-sectional area of the outlet side pipe 6 at that portion is reduced, so the flow rate of the dilution gas flowing below the element housing part 34 Therefore, the discharge of water from the drain hole 34d is promoted by the action of the negative pressure.

Next, the operation of the hydrogen sensor 1 ′ will be described.
As shown in FIG. 5B, the dilution gas flowing in the outlet side pipe 6 enters the gas detection chamber R from the gas flow portion 70 provided in the front surface FF of the element housing portion 34, and the gas After staying slightly in the detection chamber R, the gas exits from the gas flow part 70 provided in the side back part SB. Then, after the dilution gas is taken into the gas detection chamber R from the gas flow part 70 in this way, when the internal temperature is lowered and a part of the water vapor of the dilution gas is liquefied, FIG. As shown, the water droplets W are attached to the inner surface of the element housing portion 34 ′.

  At this time, the water droplet W attached to the inner surface of the peripheral wall 34a of the element housing portion 34 'flows downward due to the influence of gravity and accumulates on the bottom wall 34c. Thereby, water does not collect in the gas flow part 70 provided in the peripheral wall 34a of the element accommodating part 34 ', and clogging of the water repellent filter 72 is suppressed. Further, the water accumulated in the bottom wall 34c is discharged into the outlet side pipe 6 through the drain hole 34d (see FIG. 4) and the drainage channel 36.

According to the above, the following effects can be obtained in the first reference embodiment.
Since the two gas flow portions 70 are provided so as to overlap each other in the flow direction of the dilution gas, the dilution gas smoothly passes through the element housing portion 34 ′. Can be further suppressed, and the element accommodating portion 34 ′ protruding from the inner surface 6 b of the outlet side pipe 6 can be prevented from becoming resistant to the flow of the dilution gas as much as possible.

Since the gas flow portion 70 is provided on the peripheral wall 34a of the element housing portion 34 ′, the water liquefied in the gas detection chamber R is suppressed from collecting in the gas flow portion 70. Therefore, clogging of the gas flow part 70 (water repellent filter 72) can be suppressed.
Since the element accommodating portion 34 is provided with the drain hole 34d and the drainage channel 36 bent to the downstream side, the water accumulated inside can be drained well.

The present invention is not limited to the first reference embodiment, and can be implemented in various forms.
In the first reference embodiment, the two gas flow portions 70 are arranged on the peripheral wall 34a of the element accommodating portion 34 ′ so as to overlap in the flow direction of the dilution gas. However, the present invention is not limited to this, and the gas flow portions The position of the portion 70 may be provided at any position on the peripheral wall 34a. However, when the two gas flow portions 70 are arranged so as to overlap in the flow direction of the dilution gas as in the first reference embodiment, the dilution gas stays in the element housing portion 34 'as described above. Therefore, it is desirable to configure as in the first reference embodiment.

[ Second Reference Form]
The second reference embodiment of the present invention will be described below. In this embodiment, since the shape of the element accommodating portion of the first reference embodiment is changed, the same components as those in the first reference embodiment are denoted by the same reference numerals, and the description thereof is omitted. In the drawings, FIG. 6 is a sectional view showing the inside of the hydrogen sensor according to the second referential embodiment, FIG. 7 is E-E sectional view of FIG. 6 and (a), and FIG. 7 of (a) F- It is F sectional drawing (b).

As shown in FIG. 6, the hydrogen sensor 1 ″ according to the second reference embodiment includes an element housing portion 37 having a shape different from that of the first reference embodiment.
The element housing portion 37 has the same shape and structure as the upper half portion of the element housing portion 34 of the first reference embodiment, while the lower half portion of the peripheral wall 37a faces downward. It is formed in a tapered shape that is inclined toward the surface. Thereby, as shown to Fig.7 (a), the cross-sectional area of the element accommodating part 37 in the surface orthogonal to the flow direction of dilution gas becomes the cross-sectional area of 1st reference form ( refer Fig.5 (a)). Since the element accommodating portion 37 according to the present embodiment is smaller than the element accommodating portion 34 according to the first reference embodiment, the element accommodating portion 37 is less resistant to the flow of the dilution gas. Further, on the inclined peripheral wall 37a of the lower half portion of the element housing portion 37, as shown in FIG. 7B, two gas flow portions 70 are provided on the front surface FF and the side back portion SB, and the flow direction of the dilution gas Are provided so as to overlap each other.

  Further, a drain hole 34d, an explosion-proof filter 73, and a drainage channel 36 similar to those in the first embodiment are provided in the bottom wall 37c of the element housing portion 37. Here, as shown in FIG. 7 (a), the peripheral wall 37a around the bottom wall 37c has a mortar shape as apparent from the above description, so that the water droplet W liquefied in the gas detection chamber R is obtained. Are well collected in the drain hole 34d and discharged.

According to the above, the following effects can be obtained in the second reference embodiment.
By tilting the peripheral wall 37a of the lower half of the element accommodating portion 37, the cross-sectional area of the element accommodating portion 37 in the plane orthogonal to the flow of the dilution gas (the surface directly exposed to the dilution gas) is reduced. As a result, it is possible to minimize the resistance of 1 ″ to the flow of the dilution gas. In addition, the air off-gas discharged from the fuel cell 2 flows out smoothly, and thus air supply. Energy consumption can be suppressed.

The present invention is not limited to the second reference embodiment, and can be implemented in various forms.
In the second reference embodiment, the two gas flow portions 70 are arranged on the inclined peripheral wall 37a of the element housing portion 37 so as to overlap in the flow direction of the dilution gas, but the present invention is not limited to this, and the gas flow portion 70 The position of the flow portion 70 may be provided at any position on the peripheral wall 37a. However, as in the second reference embodiment, in the case of two gas through portion 70 is disposed so as to overlap in the flow direction of the dilution gas is first referential embodiment and the same effect (the element housing portion 37 Therefore, it is desirable that the second reference embodiment be configured.

In the second reference embodiment, the entire lower half (side back portion SB and front surface FF) of the element accommodating portion 37 is formed in a tapered shape (conical frustum shape), but the present invention is not limited to this, and the element accommodating portion 37 is formed. It is only necessary that at least the side part (the part which is directly beside the flow direction of the dilution gas) be inclined.

Further, the present invention is not limited to the real施形condition described above is carried out in various forms.
In the above embodiment, the gas to be detected is hydrogen, but the present invention is not limited to this, and may be another gas such as carbon monoxide or hydrogen sulfide. Furthermore, in the above-described embodiment, the contact combustion type gas sensor is adopted as the gas sensor. However, the present invention may be any gas sensor provided with a gas detection chamber. For example, other types such as a semiconductor type gas sensor may be used. It may be a gas sensor.

In the above embodiment, only two gas flow portions 70 are provided, but the present invention is not limited to this, and three or more gas flow portions 70 may be provided.
The first was described above, in the second reference embodiment has been arranged so as to overlap the complete two gas through portion 70 in the flow direction of the dilution gas is not limited to this, so as to overlap slightly deviate 2 Two gas flow sections 70 may be provided.

In the first and second reference embodiments having the drain hole 34d, a material having a small specific heat, such as a metal, is provided in the element housing portions 34 'and 37, so that the material can be actively used. Condensation may occur. As a specific example of this structure, for example, when the second reference form is a basic structure, a metal is formed on the upper inner surface of the peripheral wall 37a of the element housing portion 37 as shown in FIGS. In addition to providing the plate 80, a metal plate 81 having a drain hole 81a in the bottom wall 37c may be provided. Specifically, the metal plate 80 provided above the gas flow part 70 is positioned at a position where water droplets W condensed on the surface can reach only the peripheral wall 37a to the bottom wall 37c (in FIG. 8B). The side wall of the peripheral wall 37a; a position where the condensed water droplets W do not pass through the gas flow part 70) may be disposed, and the metal plate 81 may be disposed below the gas flow part 70. According to this, dew condensation around the gas flow part 70 is suppressed, and it is also possible to prevent water condensed by the metal plates 80 and 81 from adhering to the gas flow part 70.

It is a schematic structure figure showing a fuel cell system provided with a hydrogen sensor concerning a 1st embodiment. It is sectional drawing which shows the inside of the hydrogen sensor which concerns on 1st Embodiment. FIG. 3 is a cross-sectional view taken along line AA in FIG. 2 and a cross-sectional view taken along line BB in FIG. It is sectional drawing which shows the inside of the hydrogen sensor which concerns on a 1st reference form. 5A and 5B are a cross-sectional view taken along a line CC in FIG. 4A and a cross-sectional view taken along a line DD in FIG. 5A. It is sectional drawing which shows the inside of the hydrogen sensor which concerns on a 2nd reference form. It is EE sectional drawing (a) of FIG. 6, and FF sectional drawing (b) of FIG. 7 (a). It is sectional drawing (a) which shows the modification of a 2nd reference form, and GG sectional drawing (b) of Fig.8 (a).

Explanation of symbols

1,1 ', 1 "Hydrogen sensor (gas sensor)
34, 34 ', 37 Element housing part 34a, 37a Peripheral wall 34b Groove 34c, 37c Bottom wall 35 Seal member 36 Drainage path 6 Outlet side pipe (flow path)
6a Mounting seat (wall)
6b Inner surface 50 Gas detection element 51 Detection element 52 Temperature compensation element 60 Heater 70 Gas flow part 71 Opening part 72 Water repellent filter 73 Explosion-proof filter R Gas detection chamber

Claims (3)

A gas detection element for detecting hydrogen contained in the off-gas discharged from the fuel cell;
A bottom wall that has a peripheral wall and a bottom wall that is integral with the peripheral wall, and a bottomed cylindrical element storage portion that stores the gas detection element;
Before SL provided in the bottom wall, the flowed through the off-gas into and out of the element receiving portion are arranged along the flow direction of the offgas at least two gas passage unit,
With
A gas sensor attached to an upper wall of an offgas pipe through which the offgas flows so that the element housing portion protrudes into an offgas flow path ;
Wherein each gas passage portion is provided with a circular opening larger than the gas detection element in a plan view formed in the bottom wall, and a water-repellent filter provided in the opening,
In plan view, the gas detection element and the portion of the bottom wall where the gas flow part is not provided are arranged to overlap,
The gas detection element includes a detection element that is active with respect to hydrogen, and a temperature compensation element that is inactive with respect to hydrogen,
In plan view,
The first arrangement direction of the detection element and the temperature compensation element and the second arrangement direction of the at least two gas flow portions along the flow direction of the off gas are perpendicular to each other.
The first center of the detection element and the temperature compensation element overlaps the second center of the at least two gas flow portions,
A first imaginary line passing through the detection element and the temperature compensation element and a second imaginary line passing through the centers of the at least two gas flow portions along the flow direction of the off gas are cross-shaped. Intersect
The gas sensor which is characterized a call. The gas sensor according to claim 1, wherein the gas detection element includes a coil of a metal wire containing platinum. The gas sensor according to claim 2 , wherein the gas detection element includes a carrier that covers the coil and that supports a catalyst.

Images