JP2006343107A - Gas sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gas sensor for suppressing clogging of a gas flowing part structured to positively incorporate only gas, while suppressing intrusion of water by a water-repellent filter, etc. <P>SOLUTION: A hydrogen sensor 1 includes a gas detection element 60 for detecting hydrogen included in dilute gas, an element housing part B housing the detection element 60, and a gas take-in part 80 for taking the dilute gas in the housing part B. The hydrogen sensor 1 is provided on a wall of a dilute gas passage with the take-in part 80 faced to the dilute gas passage in an outlet-side pipe 6 where the dilute gas flows, and is provided with a discharge channel 44a communicating the interior of the housing part B with the exterior thereof for discharging water in the housing part B. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

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

  In general, a polymer electrolyte membrane fuel cell forms a membrane electrode assembly (MEA: Membrane Electrode Assembly) by sandwiching both sides of a polymer electrolyte membrane between a fuel electrode and an oxygen electrode. A single fuel cell stack is formed by stacking a plurality of single cells each having a joined body sandwiched between a pair of separators. 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, the hydrogen intake port (gas intake portion) of the hydrogen detector is directed downward in the vertical direction, and the hydrogen detector is provided on the upper wall of the exhaust pipe. The structure is such that light hydrogen can be taken into the hydrogen detector well. 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, 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, and thus the water vapor enters the hydrogen detector. When the internal temperature drops after entering, the water vapor is liquefied, and this liquefied water (hereinafter referred to as dew condensation 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, the present invention provides a gas sensor that can suppress clogging of a gas flow portion configured to actively take in only gas while suppressing water intrusion by a water repellent filter or the like. And

  As a means for solving the above-mentioned problems, the invention according to claim 1 is directed to a gas detection element that detects a gas to be detected contained in a gas, an element accommodating portion that accommodates the gas detecting element, and an inside of the element accommodating portion. A gas sensor provided on a wall of the gas flow path with the gas intake part facing the gas flow path through which the gas flows, The gas sensor is characterized in that a discharge passage is provided for communicating the inside and outside of the element housing portion and discharging water in the element housing portion.

According to such a gas sensor, even after the gas is taken into the element housing part from the gas taking part, even if the internal temperature of the element housing part is lowered and a part of the gas is liquefied and condensed water is generated. The condensed water is discharged out of the element housing part through a drainage channel communicating between the inside and outside of the element housing part.
Therefore, for example, even when the gas intake portion is configured to include a water repellent filter, condensed water does not accumulate in the gas intake portion (on the water repellent filter), and the gas intake portion is clogged. Can be suppressed. And since the clogging of the gas intake part is suppressed in this way, the detection accuracy of the gas to be detected can be improved and the life of the gas sensor can be improved at low cost.

  According to a second aspect of the present invention, the gas intake portion is set to face the upstream side of the gas flow path, and the discharge path is a blowing surface on which the gas taken into the element accommodating portion is blown. The gas sensor according to claim 1, wherein the gas sensor is located in the vicinity.

According to such a gas sensor, since the gas intake portion faces the upstream side of the gas flow path through which the gas flows, the gas is easily taken into the element housing portion. And when the gas taken in in the element accommodating part is sprayed on the spraying surface of an element accommodating part, the pressure of the vicinity of this spraying surface will become high, and dew condensation water will become easy to be collected near this inner surface.
Next, since the discharge path is positioned in the vicinity of the spray surface where the pressure is increased, the condensed water collected is easily discharged out of the element housing portion through the discharge path.

  The invention according to claim 3 is the gas sensor according to claim 1 or 2, wherein an inner surface of the element housing portion is inclined so that water collects in the discharge passage.

  According to such a gas sensor, since the inner surface of the element housing portion is inclined so that water collects in the discharge path, the condensed water in the element housing portion easily collects in the drainage channel by its own weight, and the condensed water is preferable. Can be drained.

  According to a fourth aspect of the present invention, the discharge path discharges water into the gas flow path, and negative pressure generating means for generating a negative pressure by increasing the flow velocity of the gas in the vicinity of the outlet of the discharge path. The gas sensor according to any one of claims 1 to 3, further comprising:

  According to such a gas sensor, since the negative pressure generating means is provided, the flow velocity of the gas near the outlet of the discharge path is increased, and a negative pressure is generated near the outlet. If it does so, it will become easy to attract the dew condensation water in an element accommodating part via a discharge channel by this negative pressure, and dew condensation water can be discharged | emitted actively.

  ADVANTAGE OF THE INVENTION According to this invention, the gas sensor which can suppress clogging of the gas flow part comprised so that only gas can be taken in actively, suppressing infiltration of water with a water repellent filter etc. can be provided. .

  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 including a hydrogen sensor according to the present embodiment.

  As shown in FIG. 1, a hydrogen sensor (gas sensor) 1 according to this embodiment is incorporated in a fuel cell system S in order to detect hydrogen in air off-gas discharged from a 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 a catalytic reaction, and the generated hydrogen ion diffuses and passes through a moderately humidified 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 piping 5 on the fuel electrode side of the fuel cell 2 to the hydrogen circulation piping 22, and through the ejector 23 to the inlet-side piping on the fuel electrode side. 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 pipe 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 pipe 25. The hydrogen off-gas can be discharged to the hydrogen discharge pipe 25 through the purge valve 24 and can be further introduced to the diluter 26 through the hydrogen discharge pipe 25.
The diluter 26 is configured to dilute the hydrogen offgas taken in from the hydrogen discharge pipe 25 with an air offgas discharged from the fuel cell 2 at an appropriate magnification 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.

≪Configuration of hydrogen sensor≫
Next, details of the hydrogen sensor 1 will be described with reference to FIGS. In the drawings to be referred to, FIG. 2 is a side sectional view of the hydrogen sensor according to the present embodiment. 3 is an X1-X1 cross-sectional view of the hydrogen sensor shown in FIG. 4 is an X2-X2 cross-sectional view of the hydrogen sensor shown in FIG.

  As shown in FIG. 2, the hydrogen sensor 1 mainly includes a case 30, a gas detection element 60, a heater 70, an element housing part B, a gas intake part 80, and negative pressure generating means. .

<Case>
The case 30 has a rectangular parallelepiped shape and protects a built-in 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 60 and a heater 70 connected to the control board, and an element accommodating portion B for accommodating these is provided so as to protrude downward. Yes.

<Gas detection element>
The gas detection element 60 detects hydrogen (detected gas) contained in the dilution gas (gas). Specifically, as shown in FIG. 3, the gas detection element 60 includes a detection element 61 and a temperature compensation element 62. It is composed of pairs. The detection element 61 is a well-known element, and is formed by coating a metal wire coil 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 62 is inactive with respect to hydrogen, and for example, the surface of a coil equivalent to that of the detection element 61 is formed by being covered with a carrier such as alumina.

  When the detection element 61 becomes high 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 61 and the temperature compensation element 62, so that the hydrogen concentration can be detected from this difference. It can be done. Note that the change in the electrical resistance value due to the ambient temperature is canceled by using the temperature compensation element 62.

<Heater>
The heater 70 heats the inside of a second element housing portion 50 (hereinafter, this internal space is also referred to as “second housing chamber 50a”), which causes condensation in the gas detection element 60. It is suppressed.

<Element housing part>
As shown in FIG. 2, the element accommodating portion B is a case that surrounds and accommodates the gas detection element 60 and the heater 70 in a double manner, and includes an outer first element accommodating portion 40 (the element accommodating portion in the claims). And the second element accommodating portion 50 inside thereof.

[First element accommodating portion]
The first element housing portion 40 is a substantially bottomed cylindrical body projecting from the lower surface of the case 30, and fits into a through hole 6 c formed in the outlet side pipe 6, and from the inner surface 6 b of the outlet side pipe 6. It protrudes and is exposed in the outlet side pipe 6.
More specifically, the first element accommodating portion 40 is formed on the downstream side of the peripheral wall 41, the bottom wall 42, the outlet side pipe 6 upstream of the outlet wall 6 and the bottom wall 42, and has a discharge path 44a. And a pipe 44. A groove 41a is formed in the circumferential direction on the outer peripheral surface of the peripheral wall 41, and a ring-shaped seal member 35 is attached to the groove 41a, and the airtightness between the peripheral wall 41 and the through hole 6c is maintained by the seal member 35. Yes.

The inclined wall 43 is an inclined portion located between the upstream side portion of the peripheral wall 41 and the bottom wall 42, and the angle formed between the inclined wall 43 and the flow direction of the dilution gas flowing through the outlet side pipe 6 is an acute angle. It has become. That is, the inclined wall 43 faces the upstream side in the outlet side pipe 6 (upstream side of the flow path in the outlet side pipe 6). The inclined wall 43 has an opening 43 a, and the opening 43 a faces the upstream side of the outlet side pipe 6. The opening 43 a is provided with a gas intake portion 80 which will be described later, and the gas intake portion 80 faces a dilution gas flow path (gas flow path) in the outlet side pipe 6.
Here, “facing upstream in the outlet side pipe 6” means that the normal vector of the outer surface of the inclined wall 43 and the normal vector of the opening 43 a are in the longitudinal direction of the outlet side pipe 6. It means that it faces the upstream side of the outlet side pipe 6 from the orthogonal direction (circular cross section direction). In other words, it means that when the hydrogen sensor 1 is irradiated with light from the upstream side of the outlet side pipe 6, the outer surface of the inclined wall 43 and the opening 43 a are illuminated and become “positive”.

  On the other hand, the inner surface of the downstream portion of the peripheral wall 41 is a spray surface 41b, and the dilution gas taken in from the gas take-in portion 80 is sprayed onto the spray surface 41b (see arrow A3 in FIG. 2). ). Thereby, in the 1st storage chamber 40a, the pressure of the spraying surface 41b vicinity becomes high.

  The bottom wall 42 is inclined so that condensed water collects in the discharge path 44a of the discharge pipe 44 located on the downstream side thereof. In other words, the inner bottom surface 42a, which is the inner surface of the bottom wall 42, is inclined so that condensed water collects in the discharge passage 44a.

The discharge pipe 44 has a discharge path 44 a and is a hollow body for discharging the condensed water in the first element housing portion 40 into the outlet side pipe 6. That is, the inside and outside of the first element housing portion 40 communicate with each other through the discharge path 44a. The discharge pipe 44 is located on the downstream side of the bottom wall 42 and in the vicinity of the spray surface 41b.
The discharge path 44a is provided with an explosion-proof filter 45 formed of a mesh capable of allowing liquid water such as condensed water to pass therethrough, thereby ensuring explosion-proof properties.
Furthermore, the discharge pipe 44 is formed to bend toward the downstream side in the flow direction of the dilution gas, and the dilution gas is prevented from entering the first storage chamber 40a from the discharge path 44a.

[Second element accommodating portion]
The second element accommodating portion 50 is a bottomed cylindrical body having a second accommodating chamber 50 a that accommodates the gas detection element 60 and the heater 70, and is disposed inside the first element accommodating portion 40. An opening 50 b is formed in the bottom wall of the second element housing portion 50. And the explosion-proof filter 52 is provided so that the opening 50b may be plugged, and explosion-proof property is ensured. Like the explosion-proof filter 45, the explosion-proof filter 52 is formed of a mesh that allows liquid water to pass therethrough, so that condensed water does not accumulate in the second storage chamber 50a.
As will be described later, the explosion-proof filter 52 may be omitted when an explosion-proof filter is stacked inside the water-repellent filter 81.

<Gas intake part>
As shown in FIG. 2, the gas intake part 80 includes an opening 43a formed in the inclined wall 43 of the first element housing part 40, and a water repellent filter 81 provided so as to close the opening 43a. Has been. The gas intake unit 80 faces the upstream side in the outlet side pipe 6 (upstream side of the flow path in the outlet side pipe 6). As a result, liquid water contained in the wet dilution gas is repelled by the water repellent filter 81 and does not enter the first storage chamber 40a while taking the gaseous dilution gas into the first storage chamber 40a. (See arrow A1 in FIG. 2). Moreover, it is good also as a structure which piles up an explosion-proof filter inside the water-repellent filter 81 in order to improve explosion-proof property.

<Negative pressure generating means>
The negative pressure (low pressure) generating means is a means for generating a negative pressure (low pressure) in the vicinity of the outlet 44b by increasing the flow rate of the dilution gas in the vicinity of the outlet 44b of the discharge passage 44a. The negative pressure generating means according to the present embodiment includes a built-up portion 91 and a pair of guides 92 and 92 (see FIG. 4).

  The built-up portion 91 (channel cross-sectional area reducing means) is provided so as to protrude from the inner surface 6b of the outlet side pipe 6 facing the outlet 44b. As a result, the flow path cross-sectional area of the outlet side pipe 6 in the vicinity of the outlet 44b is reduced, the flow rate of the dilution gas in the vicinity of the outlet 44b is increased, and a negative pressure is easily generated in the vicinity of the outlet 44b.

The pair of guides 92, 92 (gas guiding means) is a pair of elongate erected on the inner surface 6b along the flow of the dilution gas, as shown in FIG. 4, in order to introduce more dilution gas near the outlet 44b. It is a plate-like body. The pair of guides 92, 92 are narrower toward the downstream side of the flow of the dilution gas so that the guides 92, 92 have a substantially “C” shape in plan view, and the distance between the guides 92, 92 is reduced. The narrowed portion sandwiches the outlet 44b of the discharge pipe 44 and the built-up portion 91. As a result, more dilution gas is introduced near the outlet 44b, and a negative pressure is likely to be generated near the outlet 44b.
Therefore, an orifice C (throttle channel) is formed in the vicinity of the outlet 44b by the built-up portion 91 and the pair of guides 92 and 92.

Since negative pressure is easily generated in the vicinity of the outlet 44b by the negative pressure generating means including the buildup portion 91 and the pair of guides 92 and 92 in this way, the negative pressure in the vicinity of the outlet 44b causes the negative pressure in the first storage chamber 40a. Condensed water is sucked and easily discharged into the outlet side pipe 6 through the discharge path 44a (see arrow A5 in FIG. 2).
Incidentally, since the element housing part B itself protrudes from the inner surface 6b of the outlet side pipe 6, the sectional area of the outlet side pipe 6 at that portion is also reduced, so that the flow rate of the dilution gas flowing below the outlet 44b And the generation of negative pressure is promoted.

≪Operation of hydrogen sensor≫
Next, the operation of such a hydrogen sensor 1 will be described.
As shown in FIG. 2, the dilution gas flowing in the outlet side pipe 6 passes through the water repellent filter 81 of the gas intake portion 80 (see arrow A1) and is taken into the first storage chamber 40a. A part of the diluted gas thus taken in passes through the explosion-proof filter 52 (see arrow A2), enters the second storage chamber 50a, and the hydrogen concentration is detected by the gas detection element 60. In addition, a part of the dilution gas taken into the first storage chamber 40a flows in the first storage chamber 40a toward the downstream side as it is, and is sprayed to the spray surface 41b that is the inner surface of the peripheral wall 41 on the downstream side (arrow) A3). Thereby, in the 1st storage chamber 40a, the pressure of the vicinity of the spraying surface 41b becomes high.

  Thus, when the temperature of the 1st storage chamber 40a falls after taking in dilution gas from the gas taking-in part 80 in the 1st storage chamber 40a, a part of water vapor of dilution gas will liquefy and dew condensation water will become. The generated condensed water is attached to the inner bottom surface 42a.

At this time, since the inner bottom surface 42a is inclined so that water gathers toward the discharge passage 44a as described above, the dew condensation water flows on the inner bottom surface 42a toward the discharge passage 44a by its own weight (arrow). A4) and gather in the vicinity of the discharge path 44a.
The condensed water collected in the vicinity of the discharge passage 44a is pushed out to the discharge passage 44a by the increased pressure in the vicinity of the spray surface 41b and discharged from the outlet 44b into the outlet side pipe 6 (see arrow A5). ).

  On the other hand, a part of the dilution gas that has not been taken in from the gas take-in portion 80 circulates in the outlet side pipe 6 toward the downstream side. In this flow, the flow rate V1 of the dilution gas flowing in the vicinity of the outlet 44b of the discharge pipe 44 is higher than the flow rate V2 of the dilution gas upstream of the hydrogen sensor 1 by the built-up portion 91 and the pair of guides 92, 92 ( V1> V2). Thereby, a negative pressure is generated in the vicinity of the outlet 44b, and the dewed water in the first storage chamber 40a is sucked and discharged into the outlet side pipe 6 by this negative pressure (see arrow A5).

≪Effect of hydrogen sensor≫
According to the above, the following effects can be obtained in the present embodiment.
Since the discharge pipe 44 having the discharge path 44 a is provided in the first element housing portion 40, the dew condensation water in the first element housing portion 40 can be drained well into the outlet side pipe 6. Therefore, clogging of the gas intake part 80 (water repellent filter 81) can be suppressed. In addition, since the clogging of the gas intake unit 80 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. Furthermore, better sensing can be performed.
Since the gas intake part 80 is configured to face the upstream side of the outlet side pipe 6, the dilution gas can be preferably taken into the first storage chamber 40 a. And since the discharge pipe 44 is provided in the vicinity of the spraying surface 41b to which the diluted gas taken in in the 1st storage chamber 40a is sprayed, dew condensation water is utilized using the pressure which became high by being sprayed. Can be discharged.
Since the inner bottom surface 42a of the bottom wall 42 in the first element accommodating portion 40 is inclined, the dew condensation water can be collected in the discharge path 44a.
By the built-up portion 91 and the pair of guides 92, 92, negative pressure is generated in the vicinity of the outlet 44b, and the condensed water in the first element housing portion 40 can be sucked and discharged.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and the following modifications can be made without departing from the spirit of the present invention.

  In the above-described embodiment, the hydrogen sensor 1 is configured to include the negative pressure generating means including the built-up portion 91 and the guides 92 and 92. However, as illustrated in FIG. .

  In the above-described embodiment, the dew condensation water in the first element housing portion 40 is discharged into the outlet side pipe 6 by the discharge pipe 44. However, for example, as shown in FIG. It is good also as a structure which replaces with 44 and provides the discharge pipe 46 which has the discharge path 46a, and drains dew condensation water in air | atmosphere via the discharge path 46a. In this case, it is preferable to provide a sealing member 46 b on the collecting surface of the discharge pipe 46 to ensure airtightness between the discharge pipe 46 and the outlet side pipe 6.

  In the above-described embodiment, hydrogen is used as the gas to be detected. However, the present invention is not limited to this, and other gases such as carbon monoxide and hydrogen sulfide may be used. 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-described embodiment, the discharge pipe 44 having the discharge path 44a is positioned on the downstream side of the first element housing portion 40, and the inner bottom surface 42a is inclined toward the discharge path 44a. The inner surface of the first element housing portion 40 may be formed in a funnel shape (conical shape), and the discharge pipe may be provided at the bottom of the inner surface of the funnel shape.

  In the above-described embodiment, the gas intake portion 80 is provided on the inclined wall 43. However, the gas intake portion 80 only needs to face the upstream side of the outlet side pipe 6, and for example, the bottom wall It is good also as a structure which provides a gas intake part in 42. FIG.

  In the above-described embodiment, the first element accommodating portion 40 and the second element accommodating portion 50 are substantially bottomed cylindrical bodies, but the shape thereof is not limited to this, for example, an elliptical shape or a polygonal shape. It may be a simple shape.

It is a schematic block diagram which shows the fuel cell system provided with the hydrogen sensor which concerns on this embodiment. It is a sectional side view of the hydrogen sensor concerning this embodiment. It is X1-X1 sectional drawing of the hydrogen sensor shown in FIG. It is X2-X2 sectional drawing of the hydrogen sensor shown in FIG. It is a sectional side view of the hydrogen sensor which concerns on a modification. It is a sectional side view of the hydrogen sensor which concerns on a modification.

Explanation of symbols

1 Hydrogen sensor (gas sensor)
40 first element accommodating portion 40a first accommodating chamber 41 peripheral wall 41b spraying surface 42 bottom wall 42a inner bottom surface 43 inclined wall 43a opening 44 discharge pipe 44a discharge path 44b outlet 50 second element accommodating portion 50a second accommodating chamber 60 gas detection element 61 Detection element 62 Temperature compensation element 70 Heater 80 Gas intake part 81 Water repellent filter 91 Overlay part (negative pressure generating means)
92 Guide (Negative pressure generating means)
B Element housing part C Orifice S Fuel cell system

Claims (4)

A gas detection element for detecting a gas to be detected contained in the gas;
An element accommodating portion for accommodating the gas detecting element;
A gas intake portion for taking in the gas into the element accommodating portion;
With
A gas sensor provided on a wall of the gas flow path with the gas intake facing the gas flow path through which the gas flows,
A gas sensor comprising a discharge passage that communicates the inside and outside of the element housing portion and discharges water in the element housing portion. The gas intake section is set to face the upstream side of the gas flow path,
2. The gas sensor according to claim 1, wherein the discharge path is located in the vicinity of a spraying surface to which a gas taken into the element housing portion is sprayed.   The gas sensor according to claim 1, wherein an inner surface of the element housing portion is inclined so that water collects in the discharge path. The discharge path discharges water into the gas flow path,
The gas sensor according to any one of claims 1 to 3, further comprising negative pressure generating means for generating a negative pressure by increasing a flow velocity of the gas in the vicinity of an outlet of the discharge path.

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