JP2004093204A - Gas sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gas sensor easily performing calibration. <P>SOLUTION: This gas sensor is provided with a gas channel 41 extended along the thickness direction of a hydrogen sensor body in a case 21 of a hydrogen sensor 1, and an upper face of the case 21 is opened by the gas channel 41 to connect a calibration gas introducing part 42 to which the calibration gas is supplied from the external, and an opening part 27a on a bottom face 27A of a gas detection chamber 27. The gas channel 41 comprises an orifice 43 for adjusting a flow rate of the calibration gas flowing from the calibration gas introducing part 42 into the gas detection chamber 27, and a check valve 44 for regulating the gas flowing from the gas detection chamber 27 toward the calibration gas introducing part 42. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a gas sensor such as a catalytic combustion gas sensor.
[0002]
[Prior art]
Conventionally, as a gas sensor, for example, a pair of a gas detecting element made of a catalyst such as platinum and a temperature compensating element are provided, and gas detection is performed by heat generated by combustion when a gas to be detected such as hydrogen contacts the catalyst such as platinum. When the element is in a relatively high temperature state, for example, the concentration of the gas to be detected is changed according to a difference in electric resistance value generated between the temperature compensation element and a relatively low temperature state such as an ambient temperature. A gas contact combustion type gas sensor for detecting is known.
[0003]
[Problems to be solved by the invention]
By the way, in the gas sensor of the gas contact combustion type or the like as described above, the detection reference value of the gas sensor, so-called zero point, may be shifted, and it is necessary to calibrate the detection value output from the gas sensor at an appropriate timing. Occurs. Here, for example, as a gas sensor as described above, a gas contact combustion type hydrogen sensor that detects hydrogen, for example, when mounted on a vehicle such as a fuel cell vehicle equipped with a fuel cell as a power source, in this vehicle-mounted state, Further, it is desired that the hydrogen sensor be calibrated while the fuel cell is operating, for example, when the vehicle is running.
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a gas sensor capable of facilitating a calibration operation for the gas sensor.
[0004]
[Means for Solving the Problems]
In order to solve the above-mentioned problems and achieve the object, a gas sensor according to the present invention described in claim 1 has a gas detection chamber (for example, the gas detection chamber 27 in the embodiment) into which a gas to be inspected is introduced. In addition, a detection element (for example, the detection element 31 in the embodiment) for detecting a gas to be detected based on a difference between the electric resistance values and a compensation element (for example, the temperature compensation element 32 in the embodiment) are arranged. The gas sensor body has a gas flow path (for example, the gas flow path 41 in the embodiment) connected to the gas detection chamber and capable of introducing a calibration gas from the outside into the gas detection chamber. It is characterized by being formed.
[0005]
According to the gas sensor having the above configuration, the gas sensor main body is formed with the gas flow path connected to the gas detection chamber in which the detection element and the compensation element are arranged, and the gas flow path is appropriately supplied from outside the gas sensor to the gas flow path. By supplying the gas for calibration by the device, the gas for calibration can be introduced into the gas detection chamber. Thus, for example, even when the gas sensor is mounted on an appropriate system or device, calibration can be easily performed in this mounted state.
[0006]
According to the gas sensor of the present invention described in claim 2, the gas detection chamber (for example, the gas detection chamber 27 in the embodiment) into which the gas to be inspected is introduced is mounted on the basis of the difference in electric resistance between each other. A detection element (for example, the detection element 31 in the embodiment) and a compensation element (for example, the temperature compensation element 32 in the embodiment) capable of detecting the detection gas are arranged. Are connected to the calibration gas sealing section (for example, the gas storage chambers 51, 61a, 61b, and 61c in the embodiment) and the calibration gas sealing section and the gas detection chamber, and The calibration is performed from the calibration gas enclosure to the gas detection chamber through a release unit (for example, the control valve 52 and the open fuses 62a, 62b, and 62c in the embodiment) that can release the sealing state of the enclosure. Gas distribution Ability and gas flow path (e.g., a gas flow passage 41 in the embodiment) is characterized by comprising the formation and is.
[0007]
According to the gas sensor having the above-described configuration, the gas sensor body is provided with the calibration gas sealing section in which the calibration gas is sealed, and the release section is operated at an appropriate timing, so that the gas from the calibration gas sealing section is released. A calibration gas is introduced into the gas detection chamber via the gas flow path. Thus, for example, even when the gas sensor is mounted on an appropriate system or device, calibration can be easily performed in this mounted state.
[0008]
Further, in the gas sensor according to the third aspect of the present invention, the gas flow path includes a flow rate adjusting member (for example, an orifice according to the embodiment) capable of adjusting a flow rate of the calibration gas flowing into the gas detection chamber. 43) is provided. According to the gas sensor having the above configuration, the flow rate of the calibration gas introduced into the gas detection chamber is appropriately adjusted, so that the calibration process can be performed with high accuracy.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a gas sensor according to an embodiment of the present invention will be described with reference to the accompanying drawings.
The gas sensor 1 according to the present embodiment is provided in, for example, a fuel cell system 2 a including a fuel cell 2, a control device 3, and a storage device 4, and each of the pipes 11 connected to the fuel cell 2, , 14, a gas contact combustion type hydrogen sensor (gas sensor) 1 attached to the upper part in the vertical direction of the outlet side pipe 14 on the oxygen electrode side. It can be confirmed that hydrogen is not discharged into the off-gas flowing through the sensor. A detection signal output from the hydrogen sensor 1 is input to the control device 3.
[0010]
The fuel cell 2 includes a fuel cell (not shown) in which an electrolyte electrode structure in which a solid polymer electrolyte membrane made of, for example, a cation exchange membrane or the like is sandwiched between a fuel electrode and an oxygen electrode, is further sandwiched by a pair of separators. A large number of sets are stacked.
For example, as shown in FIG. 1, a fuel gas such as hydrogen supplied from the inlet side pipe 11 to the fuel electrode passes through a solid polymer electrolyte membrane in which hydrogen is ionized on the catalyst electrode of the fuel electrode and appropriately humidified. The electrons generated during the transfer to the oxygen electrode are taken out to an external circuit and used as DC electric energy. Since air containing an oxidizing gas such as oxygen is supplied to the oxygen electrode via the inlet pipe 12, for example, hydrogen ions, electrons and oxygen react to generate water at the oxygen electrode. Is done. Then, the reacted so-called off-gas is discharged out of the system from the outlet pipes 13 and 14 on both the fuel electrode side and the oxygen electrode side.
[0011]
The hydrogen sensor 1 is, for example, a gas contact combustion type hydrogen sensor, and includes a rectangular case 21 as shown in FIG. 2, for example. The case 21 is made of, for example, polyphenylene sulfide, and has flange portions 22 at both ends in the longitudinal direction. A collar 23 is attached to the flange portion 22, and a bolt 24 is inserted into the collar 23 to be fixedly fastened to each mounting seat 25 provided on the outlet pipe 14 on the oxygen electrode side. .
Further, a cylindrical portion 26 is formed on the lower surface of the case 21, the inside of the cylindrical portion 26 is formed as a gas detection chamber 27, and a flange portion 28 is formed on the inner side surface of the gas detection chamber 27 toward the inside. The inner peripheral portion of the flange portion 28 is formed as an opening as a gas introduction portion 29.
[0012]
A circuit board 30 sealed with a resin is provided in the case 21, and a detection element 31 and a temperature compensation element 32 arranged inside the tubular portion 26 are connected to the circuit board 30. Each of the elements 31 and 32 is fixed in a thickness direction of the hydrogen sensor main body from a base 34 arranged on the bottom surface 27A of the gas detection chamber 27 by a plurality of, for example, four pins 33 connected to the circuit board 30. They are arranged so as to form a pair at predetermined intervals at the height of the distance.
In addition, a sealing material 35 is attached to the outer peripheral surface of the cylindrical portion 26, and the airtightness is secured by closely contacting the inner peripheral wall of the through hole 14 a of the outlet pipe 14.
[0013]
The detection element 31 is a well-known element, and carries a catalyst made of a noble metal or the like active on hydrogen to be detected gas on the surface of a coil of a metal wire containing platinum or the like having a high temperature coefficient with respect to electric resistance. It is formed by being coated with a carrier such as alumina.
The temperature compensating element is made inert with respect to the gas to be detected, and is formed, for example, by covering the surface of a coil equivalent to that of the detecting element with a carrier such as alumina.
Then, the temperature of the detection element 31 becomes high due to the heat generated by the combustion reaction generated when hydrogen as the detection gas comes into contact with the catalyst of the detection element 31, and the temperature compensation under the ambient temperature without the combustion reaction by the detection gas occurs. Utilizing the fact that there is a difference in electric resistance between the element 32 and the element 32, the change in electric resistance due to the ambient temperature can be offset to detect the hydrogen concentration.
For example, as a state quantity related to a difference in electric resistance between the detection element 31 and the temperature compensation element 32, a voltage or a current between predetermined contacts of a circuit in which the detection element 31 and the temperature compensation element 32 are appropriately connected. Is output to the control device 3, and in the control device 3, a preset hydrogen concentration map or the like is retrieved from the storage device 4 according to a change in the detected value, and the hydrogen concentration is calculated.
[0014]
Further, a gas flow path 41 extending along the thickness direction of the hydrogen sensor main body is provided in the case 21, and the gas flow path 41 is connected to a calibration gas introduction portion 42 opened on the upper surface of the case 21 and a gas detection section. It is connected to the opening 27a on the bottom surface 27A of the chamber 27 so that a calibration gas supplied from the outside can be introduced into the gas detection chamber 27.
The gas flow path 41 has an orifice 43 for adjusting the flow rate of the calibration gas flowing from the calibration gas introduction part 42 into the gas detection chamber 27, and a calibration gas introduction part 42 from the gas detection chamber 27. And a check valve 44 for restricting the flow of gas in the direction toward.
[0015]
For example, as shown in FIG. 3, the calibration gas introduction unit 42 supplies a gas supplied from a valve device 46 provided at an end of an appropriate calibration gas storage container, for example, a portable gas storage container (cassette cylinder) 45. The nozzle 47 is detachably attached to the gas channel 41.
The calibration gas introduction unit 42 is disposed so as to surround the periphery of the opening 41 a of the gas flow path 41 on the bottom surface 48 </ b> A of the recess 48 in which the valve device 46 can be mounted. The seal member 49 is configured to be able to abut against 46A.
[0016]
The gas sensor 1 according to the present embodiment has the above-described configuration. Next, a calibration operation performed on the gas sensor 1 will be described.
First, for example, when the hydrogen sensor 1 is operated, the valve device 46 of the cassette cylinder 45 filled with the calibration gas is mounted in the concave portion 48 of the calibration gas introduction unit 42, and the gas supply nozzle 47 is inserted into the gas flow channel 41. Inserted. At this time, the airtightness in the gas flow path 41 is ensured by bringing the distal end surface 46A of the valve device 46 into contact with the sealing material 49.
Then, the supply of the calibration gas from the gas supply nozzle 47 is started by an operation of an appropriate operation member (not shown) provided in the valve device 46, for example.
The flow rate of the calibration gas flowing in the gas flow path 41 is appropriately adjusted in the orifice 43, and the check valve 44 restricts the backflow toward the cassette cylinder 45, and the gas flows into the gas detection chamber 27. be introduced.
Then, while the supply of the calibration gas is maintained, an appropriate calibration process is performed based on the detection value output from the hydrogen sensor 1.
[0017]
As described above, according to the gas sensor 1 of the present embodiment, by providing the gas flow path 41 capable of introducing the calibration gas supplied from outside into the gas detection chamber 27 of the hydrogen sensor 1, for example, Even when the battery system 2a is operating, the calibration operation for the hydrogen sensor 1 can be easily executed at an appropriate timing.
[0018]
In the above-described embodiment, the calibration gas is introduced from the outside. However, the present invention is not limited to this. For example, as in the first modification of the embodiment shown in FIG. A gas storage chamber 51 for storing a gas for use in calibration, and a bottom surface 27A of the gas detection chamber 27 via a control valve 52 capable of sealing and opening the gas storage chamber 51 and an orifice 43 for adjusting the flow rate of the gas for calibration. A gas flow path 41 connected to the upper opening 27a may be provided.
In this case, when the calibration operation for the hydrogen sensor 1 is performed, the control valve 52 is set to the open state by, for example, the control of the control device 3, and the calibration gas flows from the gas storage chamber 51 into the gas detection chamber 27. Let it.
[0019]
In this case, a plurality of, for example, three gas storage chambers 61a, 61b, and 61c for storing a calibration gas are provided in the case 21, as in a second modification of the present embodiment shown in FIG. The gas fuses 62a, 62b, 62c capable of releasing the sealed state of the gas storage chambers 61a, 61b, 61c and the gas flow paths 64a, 64b, 64c provided with the check valves 63a, 63b, 63c merge. The gas flow path 41 is formed, and the gas flow path 41 is provided with an orifice 43 for adjusting the flow rate of the calibration gas, and the gas flow path 41 is connected to the opening 27 a on the bottom surface 27 A of the gas detection chamber 27. You may let it.
In this case, when performing the calibration operation for the hydrogen sensor 1, for example, the open fuses 62a, 62b, 62c are operated under the control of the control device 3, and the sealed state of each gas storage chamber 61a, 61b, 61c is changed. The calibration gas is released from each gas storage chamber 61a, 61b, 61c into the gas detection chamber 27. Accordingly, the calibration operation can be performed by the calibration gas supplied to each of the gas storage chambers 61a, 61b, and 61c, and the calibration can be performed a plurality of times by providing the plurality of gas storage chambers.
[0020]
In the above-described embodiment, the calibration gas introduction unit 42 is opened at the upper surface of the case 21. However, the present invention is not limited to this. For example, the calibration gas introduction unit 42 may be arranged at another position on the outer peripheral surface of the hydrogen sensor body. Is also good.
[0021]
In the present embodiment described above, the gas sensor is the hydrogen sensor 4, but the gas sensor is not limited to this, and may be a gas sensor that detects another gas, for example, a combustible gas such as carbon monoxide or methane.
Further, the gas sensor is not limited to the gas contact combustion type gas sensor, and may be another gas sensor including a gas detection chamber into which the gas to be inspected is introduced.
[0022]
【The invention's effect】
As described above, according to the gas sensor of the present invention, for example, even when the gas sensor is mounted on an appropriate system or device, calibration can be easily performed in this mounted state.
Further, according to the gas sensor of the present invention, since the flow rate of the calibration gas introduced into the gas detection chamber is appropriately adjusted, the calibration process can be performed with high accuracy.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a fuel cell system including a gas sensor according to one embodiment of the present invention.
FIG. 2 is a schematic sectional view of the gas sensor shown in FIG.
FIG. 3 is an enlarged view showing a calibration gas introduction unit shown in FIG. 2;
FIG. 4 is a schematic sectional view of a gas sensor according to a first modification of the embodiment.
FIG. 5 is a schematic sectional view of a gas sensor according to a second modification of the present embodiment.
[Explanation of symbols]
1 gas sensor 27 gas detection chamber 31 detection element 32 compensation element (temperature compensation element)
41 gas flow path 43 orifice (flow rate adjusting member)
51, 61a, 61b, 61c Gas storage chamber (gas filling part for calibration)
52 Control valve (opening part)
62a, 62b, 63b Open fuse (release part)

Claims (3)

In the gas detection chamber into which the gas to be inspected is introduced, a detection element and a compensation element that detect the gas to be detected based on the difference in electric resistance between each other are arranged,
A gas sensor, wherein a gas flow path connected to the gas detection chamber and configured to allow introduction of a calibration gas from the outside into the gas detection chamber is formed in the gas sensor main body. In the gas detection chamber into which the gas to be inspected is introduced, a detection element and a compensation element capable of detecting the gas to be detected based on the difference in electric resistance between each other are arranged,
The gas sensor body has a calibration gas filling section in which a calibration gas is filled,
The calibration is performed from the calibration gas filling section to the gas detection chamber through a release section connected to the calibration gas filling section and the gas detection chamber and capable of releasing a sealed state of the calibration gas filling section. A gas sensor comprising: a gas passage through which a use gas can flow. 3. The gas flow path according to claim 1, wherein a flow rate adjusting member capable of adjusting a flow rate of the calibration gas flowing into the gas detection chamber is provided. Gas sensor.

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