JPS61292039A - Device for distriminating adsorption quantity of gas - Google Patents

Abstract

PURPOSE:To detect the trace gas in gas by discriminating the adsorption quantity thereof from the change in a resonance frequency characteristic when the gaseous molecules are adsorbed to an adsorptive material integrally fixed to an oscillator. CONSTITUTION:The oscillator 2 is a magnetostrictive oscillator wound with an excitation coil 5 and the gas component adsorptive material 4 formed porous is fixed to the top end of the horn 3. A rod 9 wound with an oscillation detecting coil 8 apart at a spacing therefrom is integrally mounted to the oscillator 2 to constitute the sensor. The coil 8 is connected to a detecting circuit 10. An excitation power source 11 sweeps the excitation coil 5 in a frequency range including the natural frequency of the oscillator 2. The gas to be inspected in the gas flowing in a passage 1 is adsorbed on the material 4 of the horn 3. The natural frequency of the oscillator 2 decreases with an increase in the weight in this stage and therefore the adsorption quantity is discriminated by utilizing such relation.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a gas adsorption amount determining device for detecting a weak gas in a gas.

(Prior art) As a means of detecting a specific gas in a gas, a substance that selectively adsorbs the specific gas is used, and the amount of gas adsorbed can be reduced by detecting the change in conductivity that accompanies the adsorption of the gas. Making a judgment.

(Problems to be Solved by the Invention) However, according to the prior art described in -F, the gas content in the air cannot be detected unless it is at most top per million.

゛(Means for Solving the Problems) ゛The gas adsorption amount determining device of the present invention includes an adsorbing substance that is integrally fixed to a vibrator and that adsorbs one or more specific gases, and the vibrator has a natural frequency. A fixed or variable frequency excitation power supply that applies an electric signal to the vibrator so that it vibrates at or near a frequency, a sensor that detects the vibration of the vibrator, and a resonant vibration of the detection output detected by the sensor. (Embodiment) An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows an example of the apparatus according to the present invention, where l is a passage through which a gas containing the gas to be detected flows, and the object to be measured may be a room or the atmosphere, etc., instead of the passage. The vibrator 2 is a magnetostrictive vibrator having an excitation coil 5 wound thereon, and a porous gas component adsorbing material 4 is fixed to the tip of the horn 3. The vibrator 2 is mounted on a flange 6.
It is attached by installing it on the frame of the passage 1 via the buffer member 7. The vibrator 2 includes a vibration detection coil 8.
A rod 9, which is wound at intervals, is integrally wound to constitute a sensor, and the coil 8 is connected to a detection circuit IO. Reference numeral 11 denotes an excitation power source that energizes the excitation coil 5 and sweeps the frequency in a frequency range that includes the natural frequency of the vibrator 2. The control device 12 has a function of setting the frequency variable range of the excitation power source 11 and transmitting a signal from the detection circuit 10 as data to the arithmetic device 13.
has a configuration in which the adsorption amount is calculated based on the principle described later with reference to data stored in the storage device 14, and outputted from the output device 15, which is a display or printing device.

In this device, as shown in FIG. 3, there is a correlation between the weight of the vibrator 2 including the horn 3 and the adsorbed substance 4 and the natural frequency f, and as the weight increases, the natural frequency f decreases. The amount of adsorption is determined using the relationship. That is, first, when the adsorption amount is zero or the reference amount, the detection circuit lO corresponding to the frequency shown by the curve 16 in FIG.
The detection output is input to the arithmetic unit 13 via the control device 12. The arithmetic device 13 detects the peak of the detection output by the peak holding means, and stores the frequency at that time, that is, the resonance frequency f1, in the storage device 13. On the other hand, after adsorbing the gas molecules to the adsorbent substance 4, the A frequency sweep using the excitation power source 11 similar to that shown in FIG.
A detection output as shown in is obtained, a resonance frequency f2 is detected by peak detection, a frequency difference fl-f, -Δf is obtained, an adsorption amount ΔW is calculated from this, and the output device 15 outputs it.

When detecting the amount of adsorption using such a device, Nb20 is added to 5n02 with a trace amount of Pd added as adsorbent material 4.
When propane gas was detected by adding a small amount of transition metal such as B, it was possible to detect the gas even if the gas content was about 5 PP.

4 and 5 show other embodiments of the present invention. In this embodiment, the vibrator 2' is an electrostrictive vibrator, and the excitation power source 11' generates an alternating current voltage with a fixed frequency. □Output the magnitude of the vibration output detected by the piezoelectric sensor or strain gauge sensor 8 to the computing device 13'.1.
The calculation device 13' calculates P, -P2-ΔPA from the detection output P when the adsorption amount is zero or the reference amount (frequency is f+) and the detection output P2 after adsorption, and calculates P, -P2-ΔPA. From the relationship between ΔP and adsorption amount stored in advance, Δ
The adsorption amount corresponding to a is determined and output from the output device 15. The adsorption amount may be calculated from the difference ΔP between the peak values shown in FIG. Even with this method, gas can be detected with the same accuracy as described above.

Note that the adsorbent used in the present invention includes 5
In addition to those based on n02, ZnO1T i 02. , WO3, C0304, In304,
Col, xMg, ) (0,ye Fe203, V20
5, MgFe2 o4. Oxides such as BaTiOx or additives thereof, carbon, anthracene, Cu-phthalocyanine, polyvinyl carbazole, etc. are used.

(Effects of the Invention) According to the present invention, since the amount of adsorption is determined from the change in resonance frequency characteristics when gas molecules are adsorbed to the adsorbent substance integrally fixed to the vibrator, the amount of adsorption is determined from the change in the resonance frequency characteristics. can be detected.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention, FIGS. 2 and 3 are explanatory diagrams explaining the operating principle of the embodiment, and FIG. 4 is a block diagram showing another embodiment of the present invention. , FIG. 5 is an explanatory diagram illustrating the operating principle of the embodiment of FIG. 4.

Claims (1)

[Claims] An adsorbent that is integrally fixed to the vibrator and adsorbs one or more specific gas molecules, and a variable or fixed frequency that applies an electrical signal to the vibrator so that the vibrator vibrates at or near its natural frequency. A gas adsorption device comprising: an excitation power source; a sensor that detects the vibration of the vibrator; and an arithmetic device that determines the amount of gas adsorption from the resonance vibration characteristics of the detection output detected by the sensor. Quantity discrimination device.