JPH07280697A - Optical reflection type remote gas detector - Google Patents

Abstract

PURPOSE:To improve the sensitivity of an optical reflection type remote gas detector. CONSTITUTION:The optical reflection type remote gas detector is composed of an optical transmitter and receiver 1 and a reflector 4 for detecting light mounted while holding the place of the object of gas detection, the reflector 4 constitutes the repeating reflecting section 5 of detecting light, and the optical reflection type remote gas detector is installed at the place of the object of gas detection. Accordingly, the partial leakage of a gas having a low concentration can be detected remotely with a high sensitivity. The reflector can be configured at an extremely lowerer cost than the gas detector, thus reducing the cost even when there are a large number of the places of the objects of gas detection.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas detection device, and more particularly to a light reflection type remote gas detection device used for the purpose of remotely monitoring local gas leakage in various devices and pipes in factories. Is.

[0002]

2. Description of the Related Art As a conventional method for monitoring gas leakage, a suction type or diffusion type gas detector is installed and monitored at each monitoring target point, a transmitting device and a light receiving device for detecting light such as infrared rays. A method of installing a device across a monitoring area, receiving detection light emitted from a light transmitting device and passing through the monitoring area in a light receiving device, and monitoring leakage by absorption of a specific wavelength by gas,
A transmitting / receiving device for detecting light such as infrared rays is installed on one side of the monitoring area, and a reflecting object for detecting light is installed on the other side, and the detecting light emitted from the transmitting / receiving device and passing through the monitoring area is reflected by the reflecting object. There is also a method of monitoring leakage by absorption of a specific wavelength as in the case of receiving by a light transmitting / receiving device.

[0003]

The above-mentioned conventional techniques have the following problems. In this method, since an expensive gas detector must be installed at each monitoring target location, the cost required for initial and maintenance is large. In addition, it is difficult to immediately detect the leaked gas because sampling is required. In the method (1) and (2), since the sensitivity characteristic is proportional to the product of the optical path length and the concentration of the leaked gas, it is difficult to locally detect the low concentration gas. Therefore, an object of the present invention is to solve such a problem.

[0004]

In order to solve the above-mentioned problems, the present invention comprises a detection light sending / receiving device and a reflecting device which are installed with a gas detection target portion interposed therebetween. We propose a light-reflecting remote gas detector that is installed at a gas detection target by configuring a repetitive reflector for the detection light.

In the present invention, in the above structure, the repetitive reflection unit further reflects the incident light in the right-angled direction and the first inclined reflection surface, and further reflects the light beam reflected by the first inclined reflection surface in the right-angled direction. It is proposed that the second inclined reflecting surface that returns to the direction parallel to the incident direction by the second inclined reflecting surface and the third reflecting surface that reflects the light beam reflected by the second inclined reflecting surface in the incident direction.

Further, the present invention proposes that in the repetitive reflection portion having the above-mentioned structure, a pair of inclined reflection surfaces arranged in parallel is formed on the opposite side of the first inclined reflection surface.

Next, according to the present invention, a gently inclined reflecting surface that is gently inclined with respect to the incident direction of the detection light, and a reflection that is smaller than this slightly inclined reflecting surface and that is installed facing this gently inclined reflecting surface. We propose to construct a repetitive reflector from the surface.

In the present invention, it is proposed that, in the repetitive reflection part having the above-mentioned structure, the gently inclined reflection surface or the reflection surface is formed as a curved surface.

Further, the present invention proposes that in the repetitive reflection portion having the above-mentioned structure, a pair of inclined reflection surfaces arranged in parallel is formed on the opposite side of the gently inclined reflection surface.

[0010]

The detection light emitted from the light-transmitting portion of the light-transmitting / light-receiving device reaches the reflecting device, is repeatedly reflected by the repetitive reflecting portion, then exits from the repetitive reflecting portion, returns to the light-receiving device direction, and is received by the light-receiving portion. It

When the gas leaked from the gas detection target portion reaches the repetitive reflection portion, the leaked gas reaches the repetitive reflection portion of the reflection device and is exposed to the detection light. Therefore, the detection light crosses the gas each time it is repeatedly reflected, so that the optical path length across the gas is extended and the amount of attenuation of the detection light by the gas increases, so that the sensitivity becomes high.

[0012]

Embodiments of the present invention will now be described with reference to the drawings.
1 and 2 conceptually show the gas detecting device of the present invention. Reference numeral 1 is a device for transmitting and receiving detection light, and a light transmitting portion 2 and a light receiving portion 3 are integrally formed. The light transmitting unit 2 and the light receiving unit 3 can be formed at positions separated from each other, that is, the light transmitting device and the light receiving device can be formed separately. The detection light may be visible light, infrared light, or the like,
The light source is also appropriate. Reference numeral 4 is a reflecting device, and this reflecting device 4 constitutes a repetitive reflection part 5 of light. Then, the reflecting device 4 is installed at a gas detection target location.

As shown in FIG. 1, the reflecting device 4 may be installed in a one-to-one correspondence with the light-transmitting and light-receiving device 1. Alternatively, as shown in FIG. It is also possible to install the reflection device 4 of 4 and scan these.

FIG. 2 shows an example of a detection target location where the reflection device 4 is installed. The detection target location A on the upper side of the drawing is the location of the valve 6, and the reflection device 4 is the operating shaft 7 of the valve 6.
It is installed at the location. Also, the detection target point A on the lower side of the figure
Is the location of the connection flange 9 of the pipe 8, and the reflector 4
Is installed near the connection flange 9.

FIG. 3 is an explanatory view showing an example of the reflection device 4. In this reflection device 4, 45 ° with respect to the incident direction of light.
A first tilted reflecting surface 10 that tilts and reflects the detection light in a right-angled direction, and a ray reflected by the first tilted reflecting surface 10 is further reflected in the right-angled direction to return to a direction parallel to the incident direction. The second inclined reflecting surface 11 inclined by 45 ° and the third reflecting surface 12 reflecting the light rays reflected by the second inclined reflecting surface 11 in the incident direction constitute the repetitive reflecting section 5. Further, in the reflecting device 4, the first and second inclined reflecting surfaces 10 and 11 and the third reflecting surface 12 are constituted by the plane mirror 13.

In this structure, the detection light emitted from the light-transmitting / light-receiving device 1 is incident on the reflecting device 4 as shown by the alternate long and short dash line in the figure, and passes through the first and second inclined reflecting surfaces 10 and 11 to the third reflecting surface. To the reflection surface 12 of the light source, reflected there, passed through the second and first inclined reflection surfaces 11 and 10 again, and exited the reflection device 4 in the direction opposite to the incident direction toward the light transmission / reception device 1. Therefore, in this configuration, the detection light is the first and second inclined reflection surfaces 10 and 11.
It will be reflected and reciprocated 5 times in the space in front of.
Therefore, when gas is present in the space inside the reflection device 4,
The optical path length of the detection light that traverses the gas in this space is generally three times as long as when it is reflected once.

On the other hand, FIG. 4 is an explanatory view showing another example of the reflecting device 4. In this reflecting device 4, the first and second inclined reflecting surfaces 10 and 11 and the third inclined reflecting surfaces 10 and 11 similar to the structure of FIG. Reflective surface 12
The repetitive reflection part 5 is constituted by. However, in the reflecting device 4 of this example, unlike the example of FIG. 3, the first and second inclined reflecting surfaces 10 and 11 are formed as total reflecting surfaces by the prism 14. The path of the detection light in the repetitive reflection part 5 of this configuration is the same as that of the configuration of FIG. 3, but the optical path of the detection light in the first and second inclined reflection surfaces 10 and 11 is the prism 1.
Since it is within 4, the optical path length of the detection light traversing the gas in the reflection device 4 is generally doubled as compared with the case where it is reflected only once.

5 and 6 show still another example of the reflecting device. FIG. 5 is a partially cutaway side view, and FIG. 6 is a partially cutaway front view. The repetitive reflection section 5 of the reflection device 4 of this example has first and second inclined reflection surfaces 10 and 11 and a third reflection surface 12, as in the configuration of FIG. The inclined reflecting surfaces 10 and 11 support the plane mirror 13.

The first inclined reflecting surface 10 is arranged in the shape of a quadrangular pyramid horn, and the second inclined reflecting surface 11 is arranged in the shape of a quadrangular pyramid. A square third reflecting surface 12 facing the second inclined reflecting surface 11 is formed at a position away from the second inclined reflecting surface 11 in the front direction. Reference numerals 15 and 16 denote the plane mirror 13 and a support member for the following components.

Further, at a position apart from the first inclined reflecting surface 10 arranged in the shape of a quadrangular truncated pyramid horn to the front side, a fourth quadrangular truncated pyramid horn-like shape facing the first inclined reflecting surface 10 is formed. The inclined reflecting surface 17 is composed of the plane mirror 13, and the fourth inclined reflecting surface 17 is provided on the back surface side of the third reflecting surface 12.
The fifth sloping pyramid-shaped inclined reflecting surface 18 facing the plane mirror 1
It is composed of 3. The reflection device 4 having the above configuration is shown in FIG.
Similar to the one shown in FIG. 3, the valve is installed at the position of the operation shaft 7 of the valve, and the operation shaft 7 is made to correspond to the repetitive reflection part 5.

In this structure, the detection light emitted from the light receiving device 1 reaches the reflecting device 4 and is sequentially reflected by the fifth inclined reflecting surface 18 and the fourth inclined reflecting surface 17 as shown by the alternate long and short dash line in the figure. And then enters the first inclined reflection surface 10, and then passes through the first and second inclined reflection surfaces 10 and 11 to the third reflection surface 1.
2, the light is reflected here and again enters the fourth inclined reflection surface 17 through the second and first inclined reflection surfaces 11 and 10. Then, it exits the reflecting device 4 through the fourth inclined reflecting surface 17 and the fifth inclined reflecting surface 18, and goes toward the light receiving device 1.
In this configuration, the detection light is incident from any part of the quadrangular pyramid-shaped fifth inclined surface 18 as shown by the arrow on the lower side in the figure, and is reflected via the above-described path. As described above, in this configuration, the detection light is transmitted to the first and second inclined reflection surfaces 10 and 11.
In the space in front of, it will be reflected 9 times and will make a round trip.
Therefore, when the gas leaking from the detection target portion exists in the reflection device 4, the optical path length of the detection light that traverses the gas is generally four times as long as that when the gas is reflected once.

Next, FIG. 7 conceptually shows still another example of the reflecting device 4, in which the repeating reflecting portion 5 of the reflecting device 4 of this example is shown.
5 and 6, the fourth inclined reflection surface 17 and the fifth inclined reflection surface 17 in FIG.
Inclined reflecting surfaces 19 and 20 corresponding to the inclined reflecting surface 18 of
A reflection surface 21 corresponding to the third reflection surface 12 is formed. That is, the inclined reflecting surface 19 has a truncated pyramid horn shape, the inclined reflecting surface 20 has a quadrangular pyramid shape, and the reflecting surface 21 has a square shape.

On the other hand, at a position facing the inclined reflecting surface 19 and the reflecting surface 21, instead of the first and second inclined reflecting surfaces 10 and 11 in the examples of FIGS. Forming a gently inclined reflection surface 22.

In this structure, the detection light transmitted and emitted from the light receiving device 1 reaches the reflecting device 4, and is sequentially reflected by the inclined reflecting surfaces 20 and 19 as shown by the alternate long and short dash line in FIG. , And reaches the reflecting surface 21. The detection light reflected by the reflecting surface 21 shifts in position and reaches the gently inclined reflecting surface 22 again, where it is reflected and reaches the displaced position of the reflecting surface 21. In this way, the detection light is reflected a plurality of times between the reflecting surface 21 and the gently inclined reflecting surface, for example, in the case of the configuration shown in FIG. A reflecting device 4 which is sequentially reflected by the reflecting surfaces 19 and 20.
And goes toward the light emitting and receiving device 1.

Therefore, in this structure, when gas is present in the reflection device 4, the optical path length of the detection light traversing the gas in the reflection device 4 becomes longer as the number of repeated reflections increases.

In FIG. 7, the gently inclined reflecting surface 22 and the reflecting surface 21 are formed by plane mirrors, but at least one side of the gently inclined reflecting surface 22 or the reflecting surface 21 can be formed by a curved surface. That is, the gently inclined reflecting surface 22 can use a concave mirror having a small curvature in place of the plane mirror, and the reflecting surface 21 can use a convex mirror in place of the plane mirror.

Further, in FIGS. 3 to 7, the main parts of the repetitive reflector 5 are formed by reflecting surfaces (10, 11) and 12 which are inclined with respect to each other.
Alternatively, it is constituted by 21 and 22, but it is also possible to repeatedly constitute the reflecting portion by the parallel reflecting surfaces facing each other.
In this case, an optical element may be combined so that the detection light enters from a direction inclined with respect to the normal direction of the reflection surface, is repeatedly reflected, and then exits in the inclined direction.

Further, the specific structure of the repetitive reflecting section 5 can be appropriately constituted by combining a plurality of optical elements such as a plane mirror, a curved mirror and a prism in addition to the above-mentioned embodiment.

[0029]

As described above, according to the present invention, in the light reflection type remote gas detecting device, the reflecting device having the repetitive reflecting portion is installed at the gas detection target portion, so that the following effects can be obtained. Local low concentration gas leakage can be detected remotely with high sensitivity. Since the reflecting device can be constructed at a very low cost as compared with the gas detector, the cost is low even if there are many gas detection targets.

[Brief description of drawings]

FIG. 1 is an explanatory diagram conceptually showing the structure of a gas detection device of the present invention.

FIG. 2 is an explanatory view conceptually showing an application example of the gas detection device of the present invention.

FIG. 3 is an explanatory view conceptually showing an example of a reflection device according to the present invention.

FIG. 4 is an explanatory view conceptually showing another example of the reflecting device according to the present invention.

FIG. 5 is a side view conceptually showing another example of the reflecting device according to the present invention with a part thereof cut away.

FIG. 6 is a front view conceptually showing another example of a reflecting device according to the present invention with a part thereof cut away.

FIG. 7 is a side view conceptually showing another example of a reflecting device according to the present invention with a part cut away.

[Explanation of symbols]

 1 Transmitting / Receiving Device 2 Light Transmitting Unit 3 Light Receiving Unit 4 Reflecting Device 5 Repeating Reflecting Unit 6 Valve 7 Operating Axis 8 Piping 9 Connection Port Flange 10 First Inclined Reflective Surface 11 Second Inclined Reflective Surface 12 Third Reflective Surface 13 plane mirror 14 prisms 15 and 16 support member 17 fourth inclined reflection surface 18 fifth inclined reflection surface 19 and 20 inclined reflection surface 21 reflection surface 22 gently inclined reflection surface

Claims (7)

[Claims] 1. A detection light transmission / reception device, which is installed with a gas detection target portion sandwiched therebetween, and a reflection device, and this reflection device constitutes a repetitive reflection part of the detection light and is installed at the gas detection target portion. Light-reflecting remote gas detection device characterized in that 2. The repetitive reflector has a first inclined reflection surface that reflects incident light in a right-angled direction, and a light ray reflected by the first inclined reflection surface that is further reflected in a right-angled direction so as to be parallel to the incident direction. 2. The light-reflecting remote unit according to claim 1, further comprising a second inclined reflection surface for returning the light to the first inclined reflection surface and a third reflection surface for reflecting the light ray reflected by the second inclined reflection surface in the incident direction. Gas detector 3. The light reflection type remote gas detection device according to claim 2, wherein a pair of inclined reflection surfaces arranged in parallel is formed on the opposite side of the first inclined reflection surface. 4. The repetitive reflection part has a gently inclined reflection surface that is gently inclined with respect to the incident direction of the detection light, and a reflection that is smaller than this gently inclined reflection surface and that is installed facing this gently inclined reflection surface. 2. A surface and a surface.
Light reflection type remote gas detector described 5. The repetitive reflection part is provided with a gently inclined reflection surface that is gently inclined with respect to the incident direction of the detection light, a slightly inclined reflection surface, which is smaller than the slightly inclined reflection surface, and is opposed to the gently inclined reflection surface. 2. The light-reflecting remote gas detection device according to claim 1, wherein 6. The repetitive reflector is provided with a gently inclined reflecting surface gently inclined by a curved surface with respect to the incident direction of the detection light, with a size smaller than the gently inclined reflecting surface, and facing the gently inclined reflecting surface. 2. The light reflection type remote gas detection device according to claim 1, wherein the remote reflection gas detection device has a convex curved reflection surface. 7. The light reflection type remote gas detection device according to claim 4, wherein a pair of inclined reflection surfaces arranged in parallel is formed on the opposite side of the gently inclined reflection surface.