JP2005257394A - Hydrogen detection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect easily the concentration of gaseous hydrogen included in gas by utilizing a hydrogen storing alloy having high selectivity to hydrogen. <P>SOLUTION: This hydrogen detection device 11 has a constitution equipped with a detection element 12 comprising the hydrogen storage alloy having a temperature change characteristic of a prescribed hydrogen storing pressure, a temperature measuring resister 15b comprising platinum sandwiched from both sides by a pair of insulating members 15a, 15a, a quartz oscillator 14 sandwiched from both sides by a pair of electrodes 13a, 13b, and a Peltier element 16 for keeping the detection element 12 at a prescribed temperature corresponding to energization control by a control device 20. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a hydrogen detector that detects a hydrogen concentration in a gas.

Conventionally, for example, as a hydrogen sensor that detects hydrogen using a hydrogen storage alloy, when a hydrogen storage alloy is fixed to one surface of a substrate and a crystal unit is attached to the other surface, the hydrogen storage alloy stores hydrogen. There is known a hydrogen gas sensor (see, for example, Patent Document 1) that detects a frequency fluctuation of a crystal resonator caused by an increase in the weight of the gas and detects a hydrogen storage amount based on the detected magnitude of the frequency fluctuation.
JP-A-2-110341

By the way, in the hydrogen gas sensor according to an example of the above-described prior art, the hydrogen concentration can be detected more accurately as the rate of change in weight increase according to the hydrogen storage amount is larger. It is desired to increase the sensitivity to weight change according to occlusion.
The present invention has been made in view of the above circumstances, and provides a hydrogen detector capable of accurately detecting the concentration of hydrogen gas contained in a gas by using a hydrogen storage alloy having high selectivity to hydrogen. The purpose is to do.

  In order to solve the above-described problems and achieve the object, a hydrogen detection apparatus according to claim 1 is a hydrogen-absorbing material that reversibly absorbs and releases hydrogen (for example, detection element 12 in the embodiment). ) And state change detecting means for detecting a change in state of the hydrogen absorbing material according to absorption and release of hydrogen, and detecting a hydrogen concentration of the atmospheric gas in accordance with the state change (for example, crystal oscillation in the embodiment) 14) and a temperature sensor (for example, the insulating member 15a and the resistance temperature detector 15b in the embodiment) for detecting the temperature of the hydrogen absorbing material, and the temperature sensor has an insulating coating (for example, an implementation) It comprises a resistor (for example, a resistance temperature detector 15b in the embodiment) covered with an insulating member 15a), and is arranged adjacent to the state change detecting means.

According to the hydrogen detection device having the above-described configuration, for example, the hydrogen absorbing material made of a hydrogen storage alloy or the like reversibly absorbs and releases hydrogen in accordance with the hydrogen partial pressure and temperature of the atmosphere of the hydrogen detection device. Depending on the release, state changes such as volume, temperature and weight occur. For this reason, for example, by detecting the state change generated in the hydrogen absorbent material by the state change detection means in a state where the temperature of the hydrogen absorbent material is appropriately controlled according to the detection result of the temperature sensor, The density can be detected.
Moreover, when a temperature sensor such as a thermistor is provided as a temperature sensor by disposing a resistor (for example, a resistance temperature detector made of platinum or the like) covered with an insulating film adjacent to the state change detection means. In comparison, the weight of the hydrogen detection device can be reduced, and the detection accuracy of the hydrogen concentration when detecting a weight change as a state change occurring in the hydrogen absorbent can be improved. In addition, a resistor covered with an insulating coating is lighter and easier to reduce in size than temperature sensors such as thermistors, and easily secures the space required for installation while preventing the hydrogen detector from becoming larger. can do.

Furthermore, in the hydrogen detection device according to claim 2, the state change detection means detects a change in the amount of the hydrogen absorbent material or a change in a state quantity related to a change in the weight of the hydrogen absorbent material. .
According to the hydrogen detection device having the above configuration, the weight of the hydrogen detection device can be reduced by providing the resistor covered with the insulating film as the temperature sensor, and the hydrogen absorption material can be used according to the absorption and release of hydrogen. It is possible to detect the weight change occurring in

Furthermore, in the hydrogen detector of the invention described in claim 3, the state change detecting means is a crystal resonator.
According to the hydrogen detection device having the above-described configuration, it is possible to accurately detect a change in weight generated in the hydrogen absorbing material in accordance with absorption and release of hydrogen as a frequency variation generated in the crystal resonator.

According to the hydrogen detection device of the first aspect of the invention, the hydrogen concentration in the atmosphere of the hydrogen detection device can be detected by detecting the state change occurring in the hydrogen absorbent by the state change detection means. In addition, as a temperature sensor, a resistor covered with an insulating film is disposed adjacent to the state change detection means, so that the weight of the hydrogen detection device can be reduced compared to a case where a temperature sensor such as a thermistor is provided. It is possible to improve the detection accuracy of the hydrogen concentration when detecting a weight change as a state change occurring in the hydrogen absorbing material.
Furthermore, according to the invention described in claim 2 or claim 3, it is possible to accurately detect a change in weight generated in the hydrogen absorbent material in accordance with absorption and release of hydrogen.

Hereinafter, an embodiment of the hydrogen detector of the present invention will be described with reference to the accompanying drawings.
As shown in FIG. 1, for example, the hydrogen detector 11 according to the present embodiment includes a detection element 12, a crystal resonator 14 sandwiched between a pair of electrodes 13a and 13b, and a pair of insulating members 15a and 15a. The temperature measuring resistor 15b, the Peltier element 16, the heat transfer material 17, the water repellent filter 18, and the control device 20 are sandwiched.
And the inside of the box-shaped housing | casing 21 which has an opening part into which inspection object gas is introduce | transduced is formed as a gas detection chamber, and the inside of this housing | casing 21 is equipped with the detection element 12 and a pair of electrodes 13a and 13b. A quartz oscillator 14, a resistance temperature detector 15 b sandwiched between a pair of insulating members 15 a, 15 a, a Peltier element 16, a heat transfer material 17, and a water repellent filter 18 are accommodated outside the housing 21. A control device 20 is arranged.

The detection element 12 is made of a hydrogen storage alloy having a temperature change characteristic of a predetermined hydrogen storage pressure, and a hydrogen storage pressure (for example, 0.005 atm) at a predetermined operating temperature (for example, 100 ° C.) From the correspondence between the hydrogen partial pressure and the hydrogen concentration, it is set to correspond to a predetermined hydrogen concentration. (For example, a hydrogen partial pressure of 0.005 atm corresponds to a hydrogen concentration of 0.5%.)
Further, the detection element 12 changes in a state that occurs when hydrogen is occluded (for example, volume expansion, heat generation, weight increase, etc.) or changes in a state that occurs when the occluded hydrogen is released (for example, volume contraction, endotherm, (Weight reduction, etc.) is set to be a predetermined state change. For example, when the detection element 12 occludes hydrogen when the hydrogen partial pressure of the inspection target gas is equal to or higher than a predetermined partial pressure (for example, 0.005 atm), the weight increases by an increment Δm.
The detection element 12 is bonded onto the surface of the one insulating member 15a by an appropriate bonding method having heat resistance such as sintering, pressure bonding, thermal spraying, and adhesion.

The temperature measuring resistor 15b sandwiched between the pair of insulating members 15a and 15a includes platinum as a temperature measuring element, for example, and is energized via the control device 20. The control device 20 detects the temperature of the detection element 12 by detecting a change in resistance value corresponding to the temperature change of the resistance temperature detector 15b.
The substantially plate-shaped crystal resonator 14 is sandwiched from both sides in the thickness direction by a pair of electrodes 13a and 13b for exciting the crystal resonator 14, and one electrode 13a is the other insulation of the resistance temperature detector 15b. A change in the resonance frequency of the quartz crystal resonator 14 according to a change in the state of the detection element 12 is output to the control device 20 via the pair of electrodes 13a and 13b as bonded to the surface of the member 15a.

On the surface of the other electrode 13 b of the crystal resonator 14, a Peltier element 16 is disposed as a temperature holding device for holding the detection element 12 at a predetermined temperature. It is joined to the heat transfer material 17 arranged on the inner wall surface.
The Peltier element 16 sets the temperature of the detection element 12 to a predetermined operating temperature by absorbing or radiating heat according to energization control by the control device 20.

A plurality of heat radiation fins 22,..., 22 are provided on the outer surface of the housing 21 in which the heat transfer material 17 is disposed.
In addition, the opening of the housing 21 is provided with a water repellent filter 18 that can transmit the gas to be inspected and restricts the permeation of moisture contained in the gas to be inspected.

The hydrogen detection device 11 according to the present embodiment has the above-described configuration. Next, the operation of the hydrogen detection device 11 will be described.
The hydrogen storage alloy constituting the detection element 12 suppresses the storage of hydrogen when the hydrogen partial pressure of the atmosphere inside the casing 21 serving as the gas detection chamber is lower than each hydrogen storage pressure corresponding to the temperature, and the hydrogen partial pressure is reduced. Starts to store hydrogen when each hydrogen storage pressure according to the temperature is reached. Since the hydrogen storage alloy increases in weight when storing hydrogen, a change in the resonance frequency of the crystal resonator 14 is detected by the control device 20.
In other words, when the temperature of the detection element 12 is controlled to be a predetermined operating temperature, the resonance of the crystal resonator 14 to be detected depends on whether or not the hydrogen storage alloy constituting the detection element 12 stores hydrogen. The frequency is different, and based on the change in the resonance frequency, it is possible to detect in which concentration range the hydrogen concentration of the atmosphere is.

  For example, in a state where the temperature of the detection element 12 is maintained at a predetermined operating temperature (for example, 100 ° C.), the hydrogen partial pressure of the atmosphere satisfies the hydrogen storage pressure (for example, 0.005 atm) of the detection element 12. In the case where there is not, the detection element 12 does not occlude hydrogen and the change in the weight of the hydrogen detection device 11 is zero, so the change in the resonance frequency of the crystal unit 14 is zero, and the hydrogen concentration in the atmosphere is 0.5. Detected to be less than%.

  And when the hydrogen partial pressure of atmosphere is more than the hydrogen occlusion pressure (for example, 0.005 atm) of the detection element 12, the detection element 12 occludes hydrogen and the weight of the hydrogen detection apparatus 11 increases by increment (DELTA) m. By detecting a change in the resonance frequency of the crystal resonator 14 according to the increase in weight, it is detected that the hydrogen concentration in the atmosphere is 0.5% or more.

  As described above, according to the hydrogen detection device 11 according to the present embodiment, in addition to being able to easily and accurately detect the hydrogen concentration range of the atmosphere of the hydrogen detection device 11, the resistance temperature detector 15b is made to vibrate with quartz. By arranging adjacent to the child 14, the weight of the hydrogen detection device 11 can be reduced compared to the case where a temperature sensor having a large relative weight with respect to the detection element 12, such as a thermistor, is provided. Sensitivity when detecting a weight change as a state change occurring in the element 12, that is, the detection accuracy of the hydrogen concentration can be improved. Further, the resistance temperature detector 15b is lighter and smaller than a temperature sensor such as a thermistor, and easily secures a space required for mounting while preventing the hydrogen detector 10 from becoming larger. Can do.

  In the above-described embodiment, the change in the weight of the detection element 12 is detected by the quartz crystal resonator 14. However, the present invention is not limited to this. For example, the change in volume may be detected by a strain gauge or the like. The temperature change may be detected by

It is a block diagram of the hydrogen detection apparatus which concerns on one Embodiment of this invention.

Explanation of symbols

11 Hydrogen detector 12 Detection element (hydrogen absorbing material)
14 Crystal resonator (state change detection means)
15a Insulating member (temperature sensor, insulating coating)
15b Resistance temperature detector (temperature sensor, resistor)

Claims (3)

A hydrogen absorber that reversibly absorbs and releases hydrogen; and
A state change detecting means for detecting a state change according to absorption and release of hydrogen of the hydrogen absorbent, and detecting a hydrogen concentration of the atmospheric gas according to the state change;
A temperature sensor for detecting the temperature of the hydrogen absorbing material,
The temperature sensor is made of a resistor covered with an insulating film, and is disposed adjacent to the state change detecting means. 2. The hydrogen detection apparatus according to claim 1, wherein the state change detection unit detects a change in a weight of the hydrogen absorbent material or a change in a state quantity related to a change in the weight of the hydrogen absorbent material. The hydrogen detection apparatus according to claim 2, wherein the state change detection means is a crystal resonator.

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