JP2001074590A - Gas leak detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect a specified gas with high sensitivity, irrespective of night or day, in an area where a gas pipe is buried, using a spectroscopic measurement system with an excellent function for discriminating kinds of gas, in an on-vehicle gas-leak detector. SOLUTION: In a device capable of conducting spectroscopic measurement in a characteristic absorption band of a measured gas, the detector and a light source 2 or a beam-bending part are mounted on a front side of a vehicle 5 with arrangement to make a beam 3 from the light source 2 reach to a detection system 1, through a space having the possibility in existence of the measured gas. Leak of city gas is detected thereby highly sensitively, irrespective of day and night, the presence of wind, and wind directions.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an on-vehicle gas leak detecting device for detecting gas leak from a city gas pipe buried underground.

[0002]

2. Description of the Related Art Conventionally, as a device for detecting gas leakage from a city gas pipe buried underground, one described in Japanese Patent Application Laid-Open No. 622-285032 is known.

FIG. 5 shows a configuration of a conventional vehicle-mounted gas leak detecting device. As shown in FIG. 5, a contact type gas sensor 11 contacts a vehicle 5 running on a road with air passing below the vehicle. It is installed as follows. That is, the cylinder 12 set by the support portion 16 so that the traveling direction and the cylinder axis coincide with each other.
The gas sensor 11 is installed in a hole formed at the center side of the cylinder so as to be orthogonal to the cylinder axis. A wire mesh 14 for preventing foreign matter from entering is installed on the front surface of the gas sensor 11, and the air sucked into the hollow portion 13 of the cylinder 12. The gas sensor 11 can be brought into contact with the air, and the leak gas in the air can be detected.

[0004]

In the method of detecting a gas to be detected by the movement of a vehicle using a contact type gas sensor, the state of diffusion of the gas to be detected into the air differs depending on the presence or absence of a wind and the wind direction, and a stable detection signal is obtained. There is a problem that can not be obtained. Further, there is also a problem that the contact type gas sensor does not always have sufficient discrimination ability of the gas type and is likely to malfunction.

[0005] The present invention overcomes the above-mentioned problems, and adopts a spectroscopic measurement system having an excellent gas type identification function for a vehicle-mounted gas leak detection device, so that the gas leak detection device can be used in a gas pipe buried area.
An object is to enable high-sensitivity detection of a specific gas regardless of day or night.

[0006]

SUMMARY OF THE INVENTION In order to solve this problem, the present invention relates to an apparatus capable of performing spectroscopic measurement in a characteristic absorption wavelength band of a gas to be measured, before disturbing the gas to be detected by moving a vehicle. Mount the detector and the light source or the light beam bending part on the vehicle so that the light beam from the light source reaches the detector through the space where the gas to be measured may exist in front of the vehicle. Thus, city gas leaks can be detected with high sensitivity regardless of day or night.

Further, since the gas to be measured, which is a main component of the city gas, has a property of absorbing a specific wavelength, the gas to be measured can be identified and detected with high sensitivity by spectroscopically measuring only the wavelength.

Therefore, according to the present invention, a gas leak detecting device for a vehicle employs a spectroscopic measurement method having an excellent gas type identification function, so that a high sensitivity of a specific gas can be obtained regardless of day or night in a gas pipe embedding area. Detection can be enabled.

[0009]

The invention according to claim 1 of the present invention enables spectroscopic measurement in a characteristic absorption wavelength band of a gas to be measured,
It has a detector and a light source, and mounts the detector and the light source on the vehicle in an arrangement such that the light flux from the light source reaches the detector through a space where the gas to be measured may exist in front of the vehicle. A gas leak detection device for a vehicle, characterized in that if a gas to be measured is present in an optical path arranged in front of the vehicle, the signal absorption of a specific wavelength is reduced due to the characteristic absorption of the gas. Can be detected by spectroscopic measurement, so that the gas to be measured can be selectively detected.

According to a second aspect of the present invention, a light beam bending portion is disposed in front of the detector and the light source, and the light beam from the light source reaches the detector via the light beam bending portions.
The vehicle-mounted gas leakage detection device according to claim 1, wherein the light beam bending portion is mounted on a vehicle.
A light beam bending part is placed in front of the vehicle, and the detector and light source are placed inside the vehicle to increase the optical path length.The integrated amount of all detected gases present in the light path outside the vehicle is detected, and the detection function Has the effect of improving

According to a third aspect of the present invention, there is provided a gas leak for a vehicle according to the second aspect, wherein the light beam bending portion is formed by a concave reflecting mirror, and has a function of condensing the light beam from the light source to the detector. This is a detection device, and has a function of suppressing the rate of divergence and loss of the light flux from the light source to the detector by the concave reflecting mirror, and improving the gas detection function.

According to a fourth aspect of the present invention, the detector, the light source, and the light beam bending portion are covered with a dust cover so as not to block the optical path from the light source to the detector. 3. A gas leak detection device for a vehicle according to any one of (3), wherein a detector, a light source, and a light beam bending portion are prevented from being contaminated and attenuated by a dustproof cover, and a reduction in a gas detection function is prevented. Has an action.

According to a fifth aspect of the present invention, a detector and a light source are provided.
Or, either one of them or the beam bending part,
The vehicle-mounted gas leak detection device according to any one of claims 1 to 4, wherein the gas leak detection device can protrude forward from the state of being stored in the vehicle body during the gas leak detection operation, When moving to the site where the gas leak detection work is performed, the detector, the light source, and the light beam bending portion are housed in the vehicle body, so that the same operation function as that of a normal vehicle can be realized.

Hereinafter, an embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIGS.

(Embodiment 1) FIG. 1 shows one embodiment of a vehicle-mounted gas leak detecting apparatus according to the present invention. In FIG. 1, a detection system 1 performs an operation of spectrally measuring a light beam 3 from a light source 2. It is composed of a detector, a spectroscope, and a condenser. Here, the spectroscope may not be included in the detection system 1 but may be included in the light source 2. The signal processing system 4 functions to electrically process the signal from the detection system 1, output a measured gas detection signal, notify an operator by an alarm, and supply power to the detection system 1 and the light source 2. It comprises an electric signal processing circuit, a signal output circuit, an alarm generator, and a power supply circuit. The electric wiring 7 performs an operation of transmitting electric signals and electric power transferred between the detection system 1 and the signal processing system 4, and includes a signal cable,
It consists of a power cable and connection terminals.

Here, the light source 2 is set in front of the vehicle 5 by the support portion 6, but the detection system may be set in front. In addition, as shown in FIG.
May be set in front of the vehicle 5.

When detecting methane, which is a main component of city gas, as a detection signal of a gas to be measured, there is a characteristic absorption band near 1.6 μm. Therefore, for example, an infrared filter that transmits 1.6 μm is used for the detection system 1. It is possible to detect city gas leakage.

Here, when the width of the permeation band is narrowed so as to substantially correspond to the width of the methane absorption line, it is possible to more reliably select water vapor and other gases which may interfere with measurement. Therefore, if an etalon is added to the infrared filter, the function of detecting the gas to be measured can be enhanced.

It is not necessary to include all of these spectroscopic elements in the detection system 1; they may be included in the light source 2 or may be distributed and installed in both.

Next, as a comparative standard signal, a wavelength band having no methane absorption is selected near 1.6 μm, and measurement is performed in the same configuration as in the case of measuring the characteristic absorption band of methane.

The measurement of the measured gas detection signal and the comparison standard signal may be performed in parallel by two detection systems, or may be measured by one detection system by alternately changing the observation wavelength by time division. Is also good. A variable wavelength etalon can be used as one method of changing the observation wavelength.

Since the detector detects near-infrared wavelengths, it operates at room temperature even in a semiconductor type, and operates in PbS or InGaA.
An s detector can be recommended. If the dimensions of the infrared detection element are 0.5 mm square and the focal length of the focusing optical system is 50 mm, the field of view will be
Since it is 10 mm square at a distance of 1 m, the dimensions of the aperture surface of the light source are designed by this calculation. That is, the aperture size is set to cover the viewing area. The focusing optical system may use a glass lens or a concave concave mirror that is transparent to near infrared rays.

The signal processing system 4 continuously processes the data from the detection system 1 and pays attention to the ratio between the measured gas detection signal and the comparison standard signal. Can be detected. That is, when the gas to be measured does not exist, the ratio between the two signals is stable at a certain value. Therefore, when a city gas leak occurs, methane, which is the gas to be measured, is mixed in the measurement visual field, and only the detection signal for the gas to be measured is reduced, and the ratio between the two signals is reduced. Therefore, if the signal ratio is continuously observed, detection of the gas to be measured, that is, city gas leakage can be detected.

(Embodiment 2) FIG. 3 shows another embodiment of the gas leak detecting device for a vehicle according to the present invention. In FIG. 3, the light beam bending section 8 receives the light beam from the light source 2 and sends it to the detection system 1. It performs a sending action and is composed of two reflecting mirrors. With this configuration, the optical path is expanded, and the detectable space of the gas to be measured is expanded. The number of the reflecting mirrors may be one, and it is sufficient that the light flux from the light source is sent to the detection system 1. However, since the optical paths are different, the detectable space is slightly different, but there is no inconvenience because the integrated amount of the gas to be measured existing in the optical path can be detected.

(Embodiment 3) FIG. 4 shows still another embodiment of the gas leak detecting device for a vehicle according to the present invention. In FIG. 4, the light beam bending section 9 receives the light beam from the light source 2 and detects the light. , And is composed of two concave mirrors. The dust-proof cover 10 serves to prevent the light flux from being reduced due to dirt on the concave mirror, and is configured by a cover surrounding the concave mirror so as not to block the optical path. In addition,
When the detection system 1 or the light source 2 is installed in front of the vehicle, a dustproof cover may be provided on them.

(Embodiment 4) Although not shown in the drawings, in FIGS. 1 to 4, if it is possible to store it in the vehicle including the one installed on the support portion 6, the city gas can be detected. It can save space when moving and waiting while it is not working, and it is easy to move and operate. In this case, the support unit has a configuration in which a moving mechanism, a drive unit, and a drive control unit are added.

In the above description, the detection system 1 is composed of an infrared detector and an infrared spectroscope. However, if the detection system 1 corresponds to the characteristic absorption band of the gas to be measured, it is visible, ultraviolet, etc. The detection system of the other wavelength bands can be similarly implemented.

[0028]

As described above, according to the present invention, in the city gas leak detection device, a space in which the gas to be detected can be detected can be secured wider in front of the vehicle than the contact type gas sensor, and the measured gas in that space can be secured. Since the integrated detection of gas can be performed, high sensitivity detection of a specific gas can be performed in the gas pipe burying area regardless of day or night without being substantially affected by the presence or absence of the wind and the wind direction.

[Brief description of the drawings]

FIG. 1 is a side view showing a configuration of a city gas leak detection device according to an embodiment of the present invention.

FIG. 2 is a plan view showing the configuration of the apparatus.

FIG. 3 is a plan view showing a configuration of a city gas leak detection device according to another embodiment of the present invention.

FIG. 4 is a plan view showing a configuration of a city gas leak detection device according to still another embodiment of the present invention.

FIG. 5 is a conceptual diagram showing a configuration of a conventional gas leak detection device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Detection system 2 Light source 3 Light beam 4 Signal processing system 5 Vehicle 6 Support part 7 Electric wiring 8, 9 Light beam bending part 10 Dustproof cover

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Nobuhiro Araki 3-10-1, Higashi-Mita, Tama-ku, Kawasaki-shi, Kanagawa Prefecture Inside Matsushita Giken Co., Ltd. (72) Norio Kimura 3-chome Higashi-Mita, Tama-ku, Kawasaki-shi, Kanagawa No. 10 No. 1 Matsushita Giken Co., Ltd. (72) Inventor Yuji Mogi 3-10-1, Higashi-Mita, Tama-ku, Kawasaki City, Kanagawa Prefecture F-term in Matsushita Giken Co., Ltd. JJ02 JJ11 JJ13 JJ14 KK01 LL04 NN01 PP02 2G067 AA14 BB15 BB26 CC04 DD18

Claims (5)

[Claims] 1. A spectroscopic measurement in a characteristic absorption wavelength band of a gas to be measured is provided, which has a detector and a light source, and a luminous flux from the light source passes through a space where the gas to be measured may exist in front of the vehicle. An on-vehicle gas leak detection device, wherein a detector and a light source are mounted on a vehicle so as to reach a detector. 2. A method according to claim 1, further comprising: arranging a light beam bending portion in front of the detector and the light source, and mounting the light beam bending portion on the vehicle such that the light beam from the light source reaches the detector via the light beam bending portion. The on-vehicle gas leak detection device according to claim 1, wherein: 3. The on-vehicle gas leak detection device according to claim 2, wherein the light beam bending portion is a concave reflecting mirror, and has a function of condensing the light beam from the light source to the detector. 4. A portion of the detector, the light source, and the light beam bending portion, which is provided in front of the vehicle, is covered with a dustproof cover so as not to block an optical path from the light source to the detector. An in-vehicle gas leak detection device according to claim 1. 5. The method according to claim 1, wherein the detector and / or the light source, or any one of the light beam bending portions, can be protruded forward from the state of being housed in the vehicle body during the gas leak detecting operation. An in-vehicle gas leak detection device according to any one of claims 1 to 4.