JP2008191019A - Gas sensor structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gas sensor structure capable of separating the deterioration factor, such as, moisture or the like for deteriorating a gas detection element to discharge it to the outside. <P>SOLUTION: A hydrogen sensor structure S is equipped with: off-gas piping 10 through which hydrogen flows; a gas detection element 23 for detecting hydrogen; a first gas detection chamber 32 in which hydrogen is captured, and the gas detection element 23 therein and capturing hydrogen; a second gas detection chamber 41; and an element housing part 30 having a communication passage 42 for allowing the inside of the gas piping 10 with the lower part of the second gas detection chamber 41 and a valve mechanism for connecting or cutting off the communication passage 42. The communication passage 42 is directed upward, and the communication port 43 of the communication passage 42 and the second gas detection chamber 41 is arranged above the off-gas piping 10, while the gas detection element 23 is arranged above the communication port 43. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a gas sensor structure.

  A solid polymer type fuel cell forms an MEA (Membrane Electrode Assembly) by sandwiching both sides of a solid polymer membrane between an anode (fuel electrode) and a cathode (oxygen electrode), and this membrane electrode assembly A single fuel cell stack is formed by stacking a plurality of single cells sandwiched between a pair of separators. Then, hydrogen (fuel gas) is supplied to the anode, and air (oxidant gas) is supplied to the cathode. An electrode reaction occurs at the anode and the cathode, and the fuel cell generates power.

  Since unreacted hydrogen (detected gas) is discharged from such a fuel cell, a hydrogen sensor is provided in the flow path of the off gas discharged from the fuel cell, and the hydrogen sensor detects the hydrogen concentration in the off gas. It is being monitored. The off gas contains water vapor (moisture) generated by the electrode reaction and is humid.

However, when a gas detection element that is built in a hydrogen sensor and detects hydrogen by a gas catalytic combustion method or the like is exposed to water vapor in off-gas for a long period of time, it deteriorates. Thus, for example, a gas sensor is disclosed in which a valve body that appropriately blocks intrusion of a gas to be detected is provided, and this valve body is operated by a coil spring made of a shape memory alloy that expands and contracts depending on temperature (Patent Document 1).
Japanese Utility Model Publication No. 3-40553

  However, when the hydrogen concentration in the off-gas discharged from the fuel cell is monitored with the gas sensor described in Patent Document 1, condensed water formed by condensation of water vapor in the off-gas accumulates in the gas sensor, and the gas sensor element deteriorates. There is a risk of doing.

  Therefore, an object of the present invention is to provide a gas sensor structure that can separate deterioration factors such as moisture that degrade the gas detection element from the gas detection element and discharge the deterioration factor to the outside.

  As means for solving the above-mentioned problems, the present invention provides a gas pipe through which a gas to be detected flows, a gas detection element for detecting the gas to be detected, a gas detection element accommodated therein, and a gas to be detected. A gas sensor structure comprising: a gas detection chamber in which gas is taken in; an element accommodating portion having a communication path that communicates the inside of the gas pipe with a lower portion of the gas detection chamber; and a valve mechanism that communicates or blocks the communication path. The communication path is directed upward, and the communication port between the communication path and the gas detection chamber is disposed above the gas pipe, and the gas detection element is positioned above the communication port. It is the gas sensor structure characterized by being arrange | positioned.

According to such a gas sensor structure, when the gas to be detected is not detected by the gas detection element (when not detected), the communication mechanism is blocked by the valve mechanism, and the gas detection chamber has a factor (deteriorating the gas detection element). For example, moisture can be prevented from entering.
In addition, the communication path that connects the inside of the gas pipe and the lower part of the gas detection chamber is directed upward, and the communication port between the communication path and the gas detection chamber is disposed above the gas pipe. Since the gas detection element is disposed above the communication port, a factor (for example, condensed water) that degrades the gas detection element in the communication path and the gas detection chamber is separated from the gas detection element by its own weight, and the gas Can be discharged into piping.
Note that the direction of the communication path is not limited to being vertically upward as in the embodiment described later (see FIG. 1), and may be, for example, obliquely upward. Further, the gas detection element is not limited to the vertically upper side of the communication port, but may be an obliquely upper side. Furthermore, the position of the valve mechanism is not limited to the downstream portion of the communication path, but may be a midstream portion or an upstream portion.

  Further, the valve mechanism includes a valve body that communicates or blocks the communication path and an electric motor that operates the valve body, and the valve body is in a communication position by a stationary torque of the electric motor in a non-energized state. Or it is preferable that it is the gas sensor structure characterized by being maintained in the interruption | blocking position.

  According to such a gas sensor structure, the valve element can be maintained at a communication position where the communication path is communicated or a blocking position where the communication path is blocked by the static torque of the electric motor in a non-energized state. That is, the valve body can be maintained in the communication position or the cutoff position without consuming electric power with the electric motor.

  Preferably, the gas sensor structure is characterized in that a water repellent coating layer is formed on at least one of a wall surface surrounding the communication path and a wall surface surrounding the gas detection chamber.

  According to such a gas sensor structure, since the water-repellent coating layer is formed on at least one of the wall surface surrounding the communication path and the wall surface surrounding the gas detection chamber, the gas detection element is formed on the at least one wall surface. Moisture, which is one factor that deteriorates the moisture content, becomes difficult to adhere. Thereby, moisture becomes easy to be discharged into the gas pipe.

  According to the present invention, it is possible to provide a gas sensor structure capable of separating a deterioration factor such as moisture that degrades the gas detection element from the gas detection element and discharging it to the outside.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 and 2.

≪Configuration of hydrogen sensor structure≫
A hydrogen sensor structure S (gas sensor structure) according to the present embodiment shown in FIG. 1 is a structure incorporated in a fuel cell system (not shown), for example. The fuel cell system (not shown) is mounted on a fuel cell vehicle (fuel cell moving body).
The gas detection element 23 constituting the hydrogen sensor structure S detects the concentration of hydrogen (detected gas) in the humid off-gas discharged from the solid polymer fuel cell (not shown). . However, the application location of the gas sensor structure is not limited to this, and may be a structure that detects a gas to be detected in off-gas discharged from equipment other than the fuel cell, and the gas to be detected may be other than hydrogen.
In order to secure the solid polymer membrane constituting the fuel cell in a wet state, the fuel cell is supplied with humidified hydrogen or air, and the fuel cell generates water (water vapor) by power generation. The off gas is humid. Incidentally, the off-gas may be any of an anode off-gas discharged from the anode of the fuel cell, a cathode off-gas discharged from the cathode, and a mixture thereof.

  The hydrogen sensor structure S includes an off-gas pipe 10 through which off-gas discharged from a fuel cell (not shown) flows, a hydrogen sensor 20 that detects hydrogen in the off-gas, and a communication port 43 (at the most downstream position of the communication passage 42 described later) ( A ball screw 50 that opens and closes (see FIG. 2), and an ultrasonic motor 60 as an actuator that advances and retracts (actuates) a screw rod 51 (valve element) of the ball screw 50 are mainly provided. That is, in this embodiment, the case where the valve mechanism that communicates or blocks the communication path 42 includes the ball screw 50 and the ultrasonic motor 60 is illustrated.

<Off-gas piping>
The off gas pipe 10 is connected downstream of the fuel cell, and a humid off gas flows through the inside of the off gas pipe 10. A through hole 11 serving as an off gas passage is formed in the upper wall of the off gas pipe 10.

<Hydrogen sensor>
The hydrogen sensor 20 includes a substrate 21 on which a sensor circuit is patterned, a case 22 that houses the substrate 21, a gas detection element 23 that is connected to the substrate 21 and protrudes downward from the lower surface of the case 22. And an element accommodating portion 30 that accommodates the gas detecting element 23.
The case 22 is fixed to a second element accommodating portion 40, which will be described later, by a bolt (not shown), and the second element accommodating portion 40 is fixed to the off-gas pipe 10 by a bolt (not shown).

  The gas detection element 23 is disposed in a first gas detection chamber 32 which will be described later, and is an element that detects hydrogen in the off-gas taken into the first gas detection chamber 32. The gas detection element 23 outputs an electrical signal to the substrate 21 in accordance with the detected hydrogen concentration. The substrate 21 includes a CPU, a ROM, a RAM, various interfaces, an electronic circuit, and the like, calculates a hydrogen concentration based on an electric signal from the gas detection element 23, and an ECU (Electronic Control Unit) (not shown). To output.

The type and number of gas detection elements 23 are determined in accordance with the hydrogen concentration detection method.
For example, when the hydrogen detection method is a gas catalytic combustion type, the gas detection element 23 is configured by a pair of a detection element and a temperature compensation element. Then, the hydrogen concentration is detected based on the electric resistance difference between the detection element and the temperature compensation element by utilizing the heat generated when hydrogen contacts each element and burns.
Further, when the hydrogen detection method is a semiconductor method, the gas detection element 23 is configured by a pair of a detection element and a detection element. Then, the hydrogen concentration is detected based on the resistance value generated when hydrogen comes into contact with or leaves from oxygen on the surface of each element.
Further, when the hydrogen detection method is a heat conduction method, the gas detection element 23 (hydrogen detection unit) is configured by a pair of a heater for heating hydrogen and a temperature sensor. The hydrogen concentration is detected based on the fact that hydrogen has a higher thermal conductivity than other gases.

  The element accommodating portion 30 is a housing that surrounds and accommodates the gas detection elements 23 in a double manner, and mainly includes an inner first element accommodating portion 31 and an outer second element accommodating portion 40.

  The first element housing portion 31 is a substantially bottomed cylindrical body projecting from the lower surface of the case 22 and has a first gas detection chamber 32 therein. A gas flow hole 33 is formed in the bottom wall of the first element housing portion 31, and a filter 34 is provided so as to cover the gas flow hole 33. The filter 34 is a filter that allows gas (gas) to flow while ensuring explosion-proof properties, and is configured by, for example, a layered structure of a water-repellent filter and an explosion-proof filter. The water repellent filter is a filter that transmits gas but does not transmit liquid contained in gas, and is made of, for example, a tetrafluoroethylene film. The explosion-proof filter is a filter for ensuring explosion-proof properties, and is made of, for example, a metal mesh or a porous body that allows liquid water to pass through.

The second element housing part 40 is provided so as to be fitted around the first element housing part 31, and has a second gas detection chamber 41 and a communication passage 42 inside thereof. The second gas detection chamber 41 communicates with the first gas detection chamber 32 and the communication path 42 via the filter 34. In other words, the communication portion between the second gas detection chamber 41 and the communication path 42 functions as a communication port 43 (see FIG. 2), and the communication port 43 is located on the most downstream side of the communication channel 42. And the 2nd element accommodating part 40 around the communicating port 43 becomes the valve seat 44 with which the screw rod 51 which functions as a valve body contact | abuts.
In addition to the second gas detection chamber 41, the communication passage 42 communicates with the inside of the off gas pipe 10 through the through hole 11 of the off gas pipe 10.

  As shown in FIG. 2, when the screw rod 51 is retracted from the communication port 43 and disposed at the open position, the communication port 43 opens and the communication passage 42 communicates. When the communication path 42 communicates in this way, the inside of the off-gas pipe 10 and the second gas detection chamber 41 communicate with each other via the communication path 42, and off-gas passes through the through hole 11, the communication path 42, and the communication port 43. Thus, the gas is taken into the second gas detection chamber 41 and further taken into the first gas detection chamber 32 via the filter 34.

  On the other hand, as shown in FIG. 1, when the screw rod 51 moves forward with respect to the communication port 43 and the tip 51 c is disposed at a closed position where it abuts against the valve seat 44, the communication port 43 is closed and the communication passage 42 is It is designed to be blocked. When the communication path 42 is shut off in this way, the inside of the off gas pipe 10 and the second gas detection chamber 41 are shut off so that the off gas does not enter the second gas detection chamber 41.

  Further, both contact surfaces where the tip 51c of the threaded rod 51 and the valve seat 44 abut are tapered surfaces so that the tip 51c is in close contact with the valve seat 44 and the communication port 43 is suitably closed. ing. However, the present invention is not limited to this, and at least one of the tip 51c and the valve seat 44 may be a tapered surface.

Here, the positional relationship in the height direction of the through-hole 11, the gas detection element 23, the first gas detection chamber 32, the second gas detection chamber 41, the communication passage 42, and the communication port 43 of the off gas pipe 10 will be described.
The communication passage 42 is formed substantially vertically upward from the through hole 11 formed in the top wall of the offgas pipe 10. Thereby, when condensed water adheres to the wall surface surrounding the communication path 42, the condensed water is discharged into the off-gas pipe 10 by its own weight. Therefore, the wall surface surrounding the communication path 42 is not easily deteriorated by condensed water or the like.

  The second gas detection chamber 41 is formed in a substantially vertical direction at a position shifted in the horizontal direction from the communication path 42. The communication passage 42 communicates with the lower portion of the second gas detection chamber 41 through a communication port 43 in a substantially horizontal direction. The first gas detection chamber 32 in which the gas detection element 23 is disposed is disposed substantially vertically above the second gas detection chamber 41, and the first gas detection chamber 32 and the second gas detection chamber 41 are filters. It is partitioned by 34. That is, the gas detection element 23 is disposed substantially vertically above the communication port 43.

  Thereby, when condensed water adheres to the wall surface surrounding the filter 34 or the second gas detection chamber 41, the condensed water is dropped by its own weight and then discharged to the communication passage 42 through the communication port 43. The exhaust gas is discharged into the off-gas pipe 10. Therefore, the gas detection element 23, the wall surface surrounding the second gas detection chamber 41, and the like are not easily deteriorated by condensed water. Therefore, the bottom surface of the second gas detection chamber 41 may be a tapered surface, or the communication port 43 may be formed obliquely so as to promote the discharge of condensed water.

  Further, the off gas passage extending from the through hole 11 of the off gas pipe 10 to the communication passage 42, the communication port 43, the second gas detection chamber 41, and the first gas detection chamber 32 meanders and becomes long. As a result, the contact area between the wall surrounding the passage and the off-gas increases, and water vapor (moisture) in the humid off-gas discharged from the fuel cell (not shown) is condensed until the gas detection element 23 is reached. The gas detection element 23 is not easily deteriorated by moisture.

Further, a water repellent coating layer (not shown) is formed of a fluororesin or the like on the wall surface surrounding the second gas detection chamber 41 and the wall surface surrounding the communication passage 42 including the surface of the valve seat 44. As a result, the dew condensation water is unlikely to accumulate in the second gas detection chamber 41, the communication port 43, and the communication passage 42, and the dew condensation water is discharged into the off gas pipe 10.
However, the present invention is not limited to this, and a water repellent coating layer may be formed on at least one of the wall surface surrounding the second gas detection chamber 41 and the wall surface surrounding the communication passage 42 including the surface of the valve seat 44.

<Ball screw>
The ball screw 50 is for opening and closing the communication port 43, and is a screw rod 51 (shaft) that functions as a valve body that moves forward and backward with respect to the valve seat 44 to open and close the communication port 43, a nut 52, a screw A plurality of balls 53 that roll between the rod 51 and the nut 52 are mainly provided. The nut 52 is fixed to a rotor 61 described later of the ultrasonic motor 60, and a radial bearing 54 and a radial bearing 55 are interposed between the nut 52 and a non-rotating stator 65 and housing 70 described later. . The rotor 61 and the nut 52 are integrally rotated with respect to the stator 65, the housing 70, and the like.

On the outer peripheral surface of the screw rod 51, a guide groove 51b is formed in the axial direction in addition to the spiral thread groove 51a. The guide groove 51b is inserted with the tip of a non-rotating guide member 75 whose base end is fixed to the base 69 of the ultrasonic motor 60, so that the screw rod 51 does not rotate. Yes. The depth of the guide groove 51b is designed to be shallower than the depth of the screw groove 51a so that the ball 53 does not scatter from the screw groove 51a.
Thereby, when the rotor 61 and the nut 52 rotate integrally, the screw rod 51 is guided by the guide member 75 in the axial direction corresponding to the rotation direction, that is, the valve seat 44 (the communication port 43). ) To move forward and backward. That is, the guide groove 51b and the guide member 75 constitute a rotation prevention mechanism that prevents the screw rod 51 and the nut 52 from rotating.

  The length of the guide groove 51 b corresponds to the stroke length of the screw rod 51, and both end positions of the guide groove 51 b in the axial direction are set corresponding to the open position or the closed position of the screw rod 51. Further, for example, a stopper function can be added to the guide groove 51b so that the screw rod 51 moving forward does not push the valve seat 44 too much.

<Ultrasonic motor>
The ultrasonic motor 60 moves the screw rod 51 of the ball screw 50 forward and backward, and at the closed position (see FIG. 1) or the open position (see FIG. 2) by the static torque (holding torque) in a non-energized state. It is a motor to maintain. Such an ultrasonic motor 60 mainly includes a stator 65 (stator) and a rotor 61 (rotor). The rotor 61 rotates when electric power is supplied from an external power source (not shown) (for example, a fuel cell or a battery).

  The stator 65 has a ring shape, and mainly includes a vibrating body 66, a piezoelectric body 67, and a buffer member 68. The vibrating body 66 is fixed to the base 69 via the piezoelectric body 67 and the buffer member 68. ing. The base 69 is fixed to the left end of the substantially cylindrical housing 70 fixed to the second element housing 40 in the drawing. When a high frequency voltage having a phase difference of 90 ° is applied to the piezoelectric body 67 from an external power source, a vibration wave is generated in the vibrating body 66 in the circumferential direction. The buffer member 68 softens vibration transmission from the vibrating body 66 and the piezoelectric body 67 to the base 69.

  The rotor 61 mainly includes a driving body 62 made of a thick and ring-shaped metal plate, and a resin sliding member 63 containing carbon fibers attached to the driving body 62. The rotor 61 is pressed against the vibrating body 66 of the stator 65 via a thrust bearing 72 by a disc spring 71 attached to the housing 70. Thereby, even if the ultrasonic motor 60 is in a non-energized state, the rotor 61 is less likely to be displaced in the circumferential direction with respect to the stator 65, and a large static (holding) torque is generated. As a result, the screw rod 51 fixed to the rotor 61 is maintained at the current position (open position or closed position) by static torque in a non-energized state.

  On the other hand, when a high frequency voltage is applied and a vibration wave is generated in the vibrating body 66 in the circumferential direction, the rotor 61 is rotated by using the vibration wave as a driving force, the nut 52 is rotated integrally therewith, and the screw rod 51 is moved to the valve seat. 44 is advanced and retracted.

The housing 70 is provided with a ring-shaped seal member 74 via a substantially cylindrical spacer 73. The screw rod 51 is inserted into the hollow portion of the seal member 74, and the seal member 74 seals the screw rod 51. The seal member 74 is made of a rubber material such as nitrile rubber, silicon rubber, or urethane rubber, or a resin material such as tetrafluoroethylene resin, polyamide resin, or phenol resin.
As a result, the humid off-gas is less likely to enter the nut 52 from the communication passage 42, and the ball screw 50 and the ultrasonic motor 60 are less likely to be corroded by moisture, hydrogen, and the like, thereby improving durability. it can.

≪Effect of hydrogen sensor structure≫
According to such a hydrogen sensor structure S, the following effects can be obtained mainly.
(1) When hydrogen is not detected by the gas detection element 23 by the ultrasonic motor 60 (at the time of non-detection), the screw rod 51 is moved forward to block the communication path 42, and the second gas detection chamber 41, first gas It is possible to prevent moisture that degrades the gas detection element 23 from entering the gas detection chamber 32. The case where hydrogen is not detected by the gas detection element 23 is, for example, a case where the fuel cell vehicle is stopped and the fuel cell is not generating power.
On the other hand, when the fuel cell generates power and the off gas is discharged, the screw rod 51 is retracted to open the communication path 42, and the off gas is taken into the second gas detection chamber 41 and the first gas detection chamber 32 to detect the gas. The element 23 can detect the hydrogen concentration.

  (2) In the height direction, the communication port 43 between the communication passage 42 and the lower portion of the second gas detection chamber 41 is disposed above the off-gas pipe 10, and the gas detection element 23 includes the communication port 43 and the second gas detection chamber. Since it is disposed in the first gas detection chamber 32 located above the position 41, the dew condensation water can be separated from the gas detection element 23 by its own weight and discharged into the off-gas pipe 10. Thereby, deterioration of the gas detection element 23 can be suppressed.

(3) Since a water repellent coating layer (not shown) is formed on the wall surface surrounding the second gas detection chamber 41, the wall surface surrounding the communication path 42, and the surface of the valve seat 44, dew condensation is formed in the offgas pipe 10. Water can be discharged efficiently.
(4) Since the screw rod 51 is advanced and retracted by the ultrasonic motor 60 having a large static torque, the screw rod 51 can be arranged at the open position or the closed position by a large static (holding) torque in a non-energized state. Thereby, the power consumption of the ultrasonic motor 60 can be reduced. As a result, for example, power consumption of the battery (power storage device) after the fuel cell vehicle is stopped can be suppressed.

The preferred embodiment of the present invention has been described above, but the present invention is not limited to the above-described embodiment, and the following modifications can be made without departing from the spirit of the present invention.
In the above-described embodiment, the case where the screw rod 51 of the ball screw 50 functioning as a valve body is advanced and retracted by the ultrasonic motor 60 is illustrated. Valve, globe valve, ball valve, etc.) may be operated.

In the above-described embodiment, the case where the guide groove 51b and the guide member 75 are arranged on the side opposite to the communication port 43 is exemplified, but the guide groove 51b and the guide member 75 may be arranged on the communication port 43 side. .
In addition, the screw rod 51 is illustrated as being positioned at the open position or the closed position depending on the length of the guide groove 51b in the axial direction. However, for example, when the screw rod 51 is disposed at the open position, the screw rod 51 abuts. A position contact member may be provided.

  In the above-described embodiment, the case where the most downstream communication port 43 of the communication path 42 is opened / closed by the screw rod 51 (valve element) and the communication path 42 is connected or blocked is illustrated, but the open / close position (communication / blocking position) ) Is not limited to this, and may be a midstream position of the communication path 42 or an upstream position.

  In the above-described embodiment, the valve mechanism in which the rotor 61 and the nut 52 rotate integrally and the screw rod 51 advances and retreats in the axial direction has been described (see FIGS. 1 and 2). A valve mechanism may be used.

  The valve mechanism shown in FIGS. 3 and 4 includes a ball screw 90 and an ultrasonic motor 60A. The screw rod 91 of the ball screw 90 is fixed to the rotor 61, and the screw rod 91 and the rotor 61 are rotated together. A valve body 94 is fixed to the nut 92 of the ball screw 90. A guide groove 94b is formed in the axial direction on the outer peripheral surface of the valve body 94, and a guide member 95 is inserted into the guide groove 94b. The proximal end portion of the guide member 95 is fixed to the housing 80 of the ultrasonic motor 60 </ b> A, and the housing 80 is fixed to the second element housing portion 40. A screw groove 91a is formed on the outer peripheral surface of the screw rod 91, and a plurality of balls 93 are loaded in the screw groove 91a.

When the ultrasonic motor 60A rotates, the rotor 61 and the screw rod 91 rotate together, but the nut 92 and the valve element 94 are not rotated by the guide member 95, and the rotational force of the screw rod 91 is the screw The valve body 94 is moved forward and backward with respect to the communication port 43 by being converted into an axial propulsive force by a nut 92 screwed into the rod 91.
As a result, the valve body 94 has a distal end 94c that abuts the valve seat 44, closes the communication port 43, and blocks the communication passage 42 (see FIG. 3), and the distal end 94c is separated from the valve seat 44. The communication port 43 is opened, and is arranged at an open position (see FIG. 4) where the communication passage 42 is communicated.
The length of the guide groove 94b in the axial direction corresponds to the stroke length of the valve body 94 so that the valve body 94 is positioned in the closed position (see FIG. 3) or the open position (see FIG. 4). It is configured.

Further, the valve body 94 is inserted into the seal member 82 and sealed by the seal member 82 so that water vapor, hydrogen, and the like do not enter the ultrasonic motor 60 </ b> A from the communication path 42. The seal member 82 is fixed to the second element housing portion 40 via the spacer 81.
Here, when the ball screw 91 is viewed in the axial direction, for example, the sealing member 82 is a polygon (for example, a quadrangle), and the portion (insertion portion) of the valve element 94 that is inserted through the seal member 82 is a polygon (for example, a quadrangle). The valve body 94 and the nut 92 are configured so as not to rotate with respect to the seal member 82, and the screw rod 91 and the nut 92 are not rotated.

  According to the valve mechanism having such a configuration, since the screw rod 91 on the central axis of the ultrasonic motor 60A does not move in the axial direction, the sliding portions near the rotor 61 and the stator 65 are reduced, and the rotor 61 and the stator In the vicinity of 65, moisture or the like hardly enters. Thereby, durability of 60 A of ultrasonic motors can be improved.

It is a sectional side view of the hydrogen sensor structure concerning this embodiment, and shows the closed state of a communicating port. It is a sectional side view of the hydrogen sensor structure concerning this embodiment, and shows the open state of a communicating port. It is a sectional side view of the valve mechanism part in the hydrogen sensor structure concerning a modification, and shows the closed state of a communicating port. It is a sectional side view of the valve mechanism part in the hydrogen sensor structure which concerns on a modification, and shows the open state of a communicating port.

Explanation of symbols

S Hydrogen sensor structure (gas sensor structure)
DESCRIPTION OF SYMBOLS 10 Off-gas piping 20 Hydrogen sensor 23 Gas detection element 30 Element accommodating part 31 1st element accommodating part 32 1st gas detection chamber 40 2nd element accommodating part 41 2nd gas detection chamber 42 Communication path 43 Communication port 44 Valve seat 50 Ball screw (Valve mechanism)
51 Screw rod 60 Ultrasonic motor (valve mechanism)
61 Rotor 65 Stator

Claims (3)

A gas pipe through which the gas to be detected flows;
A gas detection element for detecting the gas to be detected;
While containing the gas detection element therein, a gas detection chamber into which the gas to be detected is taken in, and an element storage portion having a communication path communicating the inside of the gas pipe and the lower portion of the gas detection chamber
A valve mechanism for communicating or blocking the communication path;
A gas sensor structure comprising:
The communication path is directed upward, and the communication port between the communication path and the gas detection chamber is disposed above the gas pipe,
The gas sensor structure, wherein the gas detection element is disposed above the communication port. The valve mechanism includes a valve body that communicates or blocks the communication path, and an electric motor that operates the valve body,
The gas sensor structure according to claim 1, wherein the valve body is maintained at a communication position or a shut-off position by a stationary torque of the electric motor in a non-energized state. The gas sensor structure according to claim 1, wherein a water repellent coating layer is formed on at least one of a wall surface surrounding the communication path and a wall surface surrounding the gas detection chamber.

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