JP7441122B2 - Gas leak detection device and gas leak detection method - Google Patents

Description

The present invention relates to a gas leak detection device and a gas leak detection method.

As a gas leak detection device, there is a detection device that detects the presence or absence of gas leakage on the road surface by installing a laser gas sensor in a vehicle and irradiating a laser onto the road surface while the vehicle is running (for example, Patent Document (see 1).

JP2009-42965A

The detection device disclosed in Patent Document 1 uses a vehicle to detect gas leakage, but because it irradiates a laser onto a single point on the road surface, the detection range in which gas leakage can be detected is narrow.

An object of the present invention is to widen the detection range in which gas leakage can be detected.

The gas leak detection device according to the first aspect includes an irradiation unit that irradiates a laser, an expansion unit that expands the laser irradiated from the irradiation unit in one direction, and a light reception unit that receives the laser expanded by the expansion unit. and a moving section that moves the irradiating section, the expanding section, and the light receiving section in a direction orthogonal to the one direction.

As described above, in the configuration of the first aspect, the expansion section expands the laser irradiated from the irradiation section in one direction, and the moving section moves the irradiation section, the expansion section, and the light receiving section in a direction perpendicular to the one direction. Therefore, the detection range is formed in a band shape. Therefore, compared to a configuration in which the moving section moves the irradiating section, the expanding section, and the light receiving section without expanding the laser irradiated from the irradiating section, the detection range in which gas leakage can be detected can be widened. Further, according to the configuration of the first aspect, gas leakage is reduced compared to a configuration in which the laser irradiated from the irradiation part is expanded in one direction and the moving part moves the irradiation part, the expansion part, and the light receiving part in one direction. The detection range that can be detected can be widened.

In the gas leak detection device according to the second aspect, the expansion section is a scanning section that scans the laser from the irradiation section along the one direction and expands in the one direction.

In this way, in the configuration of the second aspect, the scanning section scans the laser from the irradiation section along one direction and expands it in one direction, so by changing the scanning width and angle, the expansion width can be increased. Can be adjusted. Therefore, the detection range can be easily adjusted.

As described in the third aspect, the scanning section of the second aspect may have a configuration including a rotating polygon mirror.

In the gas leak detection device according to the fourth aspect, the expansion section is an optical element that expands the laser beam irradiated from the irradiation section in one direction.

In this way, in the configuration of the fourth aspect, the optical element expands the laser beam irradiated from the irradiation section in one direction. Therefore, the laser can be expanded without driving the expansion section.

As the optical element of the fourth aspect, a plano-concave cylindrical lens can be used as described in the fifth aspect.

A gas leakage detection method according to a sixth aspect includes: an irradiation section that irradiates a laser; an expansion section that expands the laser beam irradiated from the irradiation section in one direction; and a light reception section that receives the laser beam expanded by the expansion section. A gas leak detector comprising: is moved in a direction perpendicular to the one direction to detect gas leakage.

As described above, in the method of the sixth aspect, the gas leak detector having the expansion part that expands the laser irradiated from the irradiation part in one direction is moved in a direction perpendicular to the one direction, so that the detection range is formed in a band shape. be done. Therefore, the detection range in which gas leakage can be detected can be expanded compared to the case where a gas leakage detector without an expansion part is also used for detection. Further, according to the method of the sixth aspect, the detection range in which gas leakage can be detected can be expanded compared to a configuration in which the gas leakage detector is moved in one direction.

Since the present invention has the above configuration, it has the excellent effect of widening the detection range in which gas leakage can be detected.

FIG. 1 is a schematic diagram showing the configuration of a gas leak detection device according to a first embodiment. FIG. 2 is a diagram showing a light absorption spectrum of methane. FIG. 2 is a schematic diagram showing a state in which an irradiation target is irradiated with a laser in the gas leak detection device according to the first embodiment. 4A is an enlarged view of a portion 4A in FIG. 3. FIG. It is a figure which shows the detection range when the laser irradiated from the laser irradiation part is not extended. It is a figure which shows the detection range when a gas leak detector is moved in a scanning direction. It is a figure showing the detection range of the gas leak detection device concerning a 1st embodiment. FIG. 2 is a schematic diagram showing the configuration of a gas leak detection device according to a second embodiment. It is a perspective view showing the composition of the plano-concave cylindrical lens of the gas leak detection device concerning a 2nd embodiment. FIG. 7 is a schematic diagram showing a state in which a laser is irradiated onto an irradiation target in a gas leakage detection device according to a second embodiment.

An example of an embodiment according to the present invention will be described below based on the drawings.
《First embodiment》
(Gas leak detection device 10)
First, the configuration of the gas leak detection device 10 according to the first embodiment will be explained. FIG. 1 is a schematic diagram showing the configuration of a gas leak detection device 10 according to the first embodiment. Note that each figure schematically shows the configuration of the gas leak detection device 10, and the dimensional ratio of each component may differ from the actual dimensional ratio. Further, in each figure, a symbol with a ``•'' inside an ◯ indicates an arrow pointing in a direction perpendicular to the plane of the paper.

A gas leak detection device 10 shown in FIG. 1 is a device that detects gas leaks. Specifically, the gas leak detection device 10 detects a leak of gas from a gas storage section in which gas is stored. Examples of the gas to be detected include methane (specifically, city gas whose main component is methane).

Note that the gas to be detected is not limited to methane, and may include hydrocarbons other than methane (for example, butane, propane, etc.). Further, the gas is not limited to those mentioned above, and may include carbon monoxide, hydrogen sulfide, hydrogen chloride, and other gases.

Examples of the above-mentioned "gas storage section" include gas pipes through which gas flows, gas tanks in which gas is stored, and the like. Note that the gas accommodating portion is not limited to the one described above, and may be any accommodating portion in which gas is accommodated.

``Detecting a gas leak'' mentioned above means identifying the presence or absence of a gas leak, but ``detecting a gas leak'' requires identifying the location where the gas is leaking and the concentration of the leaked gas. , and the spread of the leaked gas distribution.

Specifically, the gas leak detection device 10 includes a gas leak detector 11, a moving mechanism 50, and an operating section 60, as shown in FIG. The gas leak detector 11 is a main part in the gas leak detection device 10 that is responsible for detecting gas leaks. Specifically, the gas leak detector 11 includes a housing 12 , a laser irradiation section 20 , a scanning section 30 , a laser light receiving section 40 , and a presentation section 80 .

Hereinafter, the configuration of each part of the gas leakage detection device 10 (the housing 12, the laser irradiation part 20, the scanning part 30, the laser light receiving part 40, the presentation part 80, the moving mechanism 50, and the operation part 60) will be explained.

(Gas leak detector 11)
(Case 12)
As shown in FIG. 1, the housing 12 is a box (casing) that houses components such as the laser irradiation section 20, the scanning section 30, and the laser light receiving section 40. A support (not shown) is provided inside the housing 12 to support each component. The housing 12 also has an opening (not shown) that allows the laser from the laser irradiation unit 20 and the reflected light directed toward the laser receiver 40 to pass through, or a transmission part (not shown) that allows the laser and the reflected light to pass through. have. In each figure, the laser from the laser irradiation section 20 is indicated by the symbol L1, and the reflected light directed toward the laser light receiving section 40 is indicated by the symbol L2.

(Laser irradiation section 20)
The laser irradiation unit 20 shown in FIG. 1 is an example of the irradiation unit in the claims. This laser irradiation unit 20 has a function of irradiating laser. Specifically, the laser irradiation unit 20 irradiates an infrared laser (that is, a laser having a wavelength in the infrared region) toward the irradiation target 28, as shown in FIG. The irradiation target 28 is a target to which the laser irradiation unit 20 irradiates the laser beam. For example, when the gas leak detection device 10 detects a gas leak from a gas pipe buried underground, the ground becomes the irradiation target 28.

More specifically, the laser irradiation unit 20 uses a laser having a wavelength in the near-infrared region (approximately 0.7 μm or more and less than 2.5 μm) or a wavelength in the mid-infrared region (approximately 2.5 μm or more and less than 4 μm). Emits light. More specifically, the laser irradiation unit 20 irradiates a laser beam with a wavelength corresponding to the optical absorption spectrum of methane to be detected, as described below.

Here, as shown in FIG. 2, the optical absorption spectrum of methane has the highest absorption rate near the wavelength of 3.3 (μm) in the wavelength range from 1 μm to 5 μm. Therefore, the laser irradiation section 20 irradiates the laser with a wavelength of around 3.3 (μm), for example. Note that the optical absorption spectrum of methane is relatively high even near the wavelength of 1.6 (μm), so the laser irradiation section 20 is configured to irradiate a laser having a wavelength of around 1.6 (μm). It may be.

In this way, the laser irradiation unit 20 irradiates a laser beam with a wavelength corresponding to the optical absorption spectrum of the gas to be detected. Therefore, when a gas other than methane is to be detected, the sensor is configured to irradiate a laser with a wavelength that has a relatively high absorption rate in the light absorption spectrum of the gas.

(Scanning section 30)
The scanning section 30 shown in FIG. 3 is an example of an extended section in the scope of the claims, and an example of the scanning section in the scope of the claims.

As shown in FIG. 3, the scanning unit 30 scans the laser irradiated from the laser irradiation unit 20 along a predetermined scanning direction (X direction in the figure) and expands the laser beam in the scanning direction. The scanning direction is an example of one direction in the claims.

Specifically, the scanning unit 30 includes a polygon mirror 32 (rotating polygon mirror) and a driving unit 34, as shown in FIG. The polygon mirror 32 is formed into a regular polygonal shape when viewed from above. A reflective surface 33 is formed on the outer peripheral surface (outer surface) of the polygon mirror 32 .

In the scanning section 30, the polygon mirror 32 is rotationally driven in the counterclockwise direction in FIG. 3 by the driving section 34. Thereby, the polygon mirror 32 scans the laser irradiated from the laser irradiation unit 20 along the scanning direction and expands it in the scanning direction.

Specifically, as shown in FIG. 4, a laser beam is irradiated from the laser irradiation section 20 along a tangent to the polygon mirror 32. That is, in plan view, the laser irradiation section 20 irradiates the laser in a direction along the reflective surface 33A at a specific rotational position of the polygon mirror 32. The laser at this time is irradiated to the position L1A. Then, as the polygon mirror 32 rotates, the reflective surface 33A moves to the position 33B, and the laser is reflected, so that the laser beam is irradiated in the range from the position L1A to the position L1B. Therefore, the laser scans an angle range twice as large as the outer angle of the polygon of the polygon mirror 32.

(Laser light receiving section 40 and presentation section 80)
The laser light receiving section 40 shown in FIG. 3 is an example of the light receiving section in the claims. The laser light receiving section 40 receives the laser beam expanded by the scanning section 30, as shown in FIG. Specifically, after being expanded by the scanning unit 30, the laser light receiving unit 40 is reflected by the irradiation target 28, and enters the inside of the housing 12 through an opening (not shown) or a transparent part (not shown) of the housing 12. It receives the reflected light.

Note that in the present embodiment, the laser light receiving section 40 is provided separately from the laser irradiating section 20, but the present invention is not limited to this, and the laser light receiving section 40 and the laser irradiating section 20 may be formed integrally. It's okay.

In the gas leak detection device 10, the presence of gas is detected by detecting the presence or absence of laser absorption by the laser light receiving unit 40 receiving reflected light as described above, thereby detecting gas leakage. In this manner, the gas leakage detection device 10 detects gas leakage using so-called laser absorption spectroscopy (LAS).

The presentation unit 80 shown in FIG. 1 presents the detection results to the outside (the user of the gas leak detection device 10). Specifically, for example, when the presentation unit 80 detects that there is a gas leak, it may present the detection result to the outside by sounding an alarm. Further, the presentation unit 80 may present the detection results to the outside by displaying the presence or absence of gas leakage on a display screen provided on the housing 12 or the like. Note that the presentation unit 80 may combine presentation by display on a display screen and presentation by an alarm. Further, the presentation unit 80 may present the detection results to the outside using other presentation means.

(Movement mechanism 50 and operation unit 60)
The moving mechanism 50 shown in FIG. 1 is an example of a moving unit in the claims. The moving mechanism 50 is a mechanism that moves the laser irradiation unit 20, the scanning unit 30, and the laser light receiving unit 40 in a direction (Y direction in the figure) orthogonal to the scanning direction (X direction in the figure). Specifically, the moving mechanism 50 moves the components housed in the housing 12 of the gas leak detector 11 in the orthogonal direction together by moving the gas leak detector 11 in the orthogonal direction.

Specifically, the moving mechanism 50 includes a moving body on which the gas leak detector 11 is mounted and moves in an orthogonal direction by a drive source. Specifically, as an example, the movable body is constituted by a cart that is self-propelled in an orthogonal direction by a drive source based on a movement instruction inputted through the operation unit 60. Note that the mobile object may be a vehicle or a mobility robot (for example, a Segway (registered trademark)) operated by a driver (operator). Note that as the moving mechanism 50, any mechanism other than those described above may be used as long as it moves the gas leak detector 11 in the orthogonal direction.

(Gas leak detection method using gas leak detection device 10)
Next, a gas leak detection method using the gas leak detection device 10 will be explained.

The gas leak detection method includes, for example, a placement step, a movement step, and a presentation step. In the placement step, the gas leak detection device 10 is placed at a position where the laser beam from the laser irradiation unit 20 is irradiated onto the irradiation target 28 . For example, when the gas leak detection device 10 detects a gas leak from a gas pipe buried underground, the gas leak detection device 10 is placed above the ground as the irradiation target 28.

Next, in the moving step, the gas leak detector 11 having the laser irradiation section 20, the scanning section 30, and the laser light receiving section 40 is moved in the orthogonal direction by the moving mechanism 50. Specifically, the user of the gas leak detection device 10 inputs a movement instruction through the operation unit 60. Thereby, the cart serving as the moving mechanism 50 on which the gas leak detector 11 is mounted is self-propelled in the orthogonal direction by the drive source.

Next, in the presentation step, the presentation section 80 of the gas leak detector 11 presents the detection result to the outside (the user of the gas leak detection device 10). Specifically, for example, when it is detected that there is a gas leak, the presentation unit 80 may present the detection result to the outside by sounding an alarm. Furthermore, the presentation unit 80 may present the detection results to the outside by displaying the presence or absence of gas leakage on a display screen provided on the housing 12 or the like. Note that the presentation unit 80 may combine presentation by display on a display screen and presentation by an alarm.

(Modified example of moving process)
In the above-mentioned moving process, the gas leak detector 11 was moved in the orthogonal direction by the moving mechanism 50 having a drive source, but the present invention is not limited to this. In the moving step, for example, the cart on which the gas leak detector 11 is mounted may be moved by manually pushing it in an orthogonal direction. Alternatively, a vehicle such as a bicycle on which the gas leak detector 11 is mounted may be moved in the orthogonal direction by human power. Furthermore, the user may hold the gas leak detector 11 in his hand or wear it on his body and move it in the orthogonal direction.

(Effects of gas leak detection device 10)
In the gas leak detection device 10, as described above, the scanning section 30 expands the laser irradiated from the laser irradiation section 20 in the scanning direction (X direction in the figure), and the moving mechanism 50 moves the gas leak detector 11. , in a direction perpendicular to the scanning direction (Y direction in the figure) (see FIG. 3).

Here, the moving mechanism 50 moves the gas leak detector 11 in a predetermined moving direction (the Y direction in the figure) without expanding the laser irradiated from the laser irradiating unit 20 (hereinafter referred to as "first direction"). 1 configuration), as shown in FIG. 5, the laser L1 is dotted, and the detection range (the portion indicated by the two-dot chain line A1 in the figure) is formed linearly.

In addition, a configuration (hereinafter referred to as "second configuration") in which the laser irradiated from the laser irradiation unit 20 is extended in the scanning direction (X direction in the figure) and the moving mechanism 50 moves the gas leak detector 11 in the scanning direction is also available. ), as shown in FIG. 6, the detection range (the portion indicated by the two-dot chain line A2 in the figure) is formed linearly.

On the other hand, in the gas leak detection device 10, as described above, the laser irradiated from the laser irradiation section 20 is expanded in the scanning direction (X direction in the figure), and the moving mechanism 50 moves the gas leak detector 11. Since it is moved in the orthogonal direction (the Y direction in the figure), the detection range (the portion indicated by the two-dot chain line A3 in the figure) is formed in a band shape, as shown in FIG. Therefore, compared to the first configuration and the second configuration, the detection range in which gas leakage can be detected can be widened.

Furthermore, in this embodiment, the scanning unit 30 uses the polygon mirror 32 to scan the laser irradiated from the laser irradiation unit 20 along the scanning direction and expands it in the scanning direction. The expansion width can be adjusted by changing the scanning width and angle. Therefore, the detection range can be easily adjusted.

《Second embodiment》
Next, a gas leak detection device 200 according to a second embodiment ( reference embodiment ) will be described. FIG. 8 is a schematic diagram showing a gas leak detection device 200 according to the second embodiment. Note that each figure schematically shows the configuration of the gas leak detection device 200, and the dimensional ratio of each component may differ from the actual dimensional ratio. Furthermore, parts having the same functions as those in the first embodiment are given the same reference numerals, and description thereof will be omitted as appropriate.

In the gas leak detection device 10 according to the first embodiment, the laser is expanded using the scanning unit 30, whereas in the gas leak detection device 200 according to the second embodiment, the laser is expanded using an optical element. . Specifically, as shown in FIG. 8, the gas leak detection device 200 includes a plano-concave cylindrical lens 230 (hereinafter referred to as "lens 230") in place of the scanning section 30. Lens 230 is an example of an optical element in the claims.

The lens 230 is a cylindrical lens having a concave surface 232 and a flat surface 234, as shown in FIGS. 9 and 10. Specifically, in the lens 230, the concave surface 232 faces the laser irradiation section 20, and serves as a surface onto which the laser from the laser irradiation section 20 is incident. The plane 234 faces the downstream side in the irradiation direction of the laser irradiation section 20 and serves as a surface from which the laser beam incident from the concave surface 232 is emitted. In the gas leak detection device 200, the laser beam incident through the concave surface 232 is expanded and emitted from the flat surface 234 due to the action of the lens 230, and is irradiated onto the irradiation target 28.

The laser light receiving unit 40 receives reflected light that is expanded by the lens 230, reflected by the irradiation target 28, and enters the inside of the housing 12 through the opening (not shown) or the transparent part (not shown) of the housing 12. Receive light. Note that in the gas leak detection device 200, the laser light receiving section 40 is configured integrally with the laser irradiation section 20.

In the gas leak detection device 200, similarly to the gas leak detection device 10, the lens 230 expands the laser irradiated from the laser irradiation unit 20 in a predetermined expansion direction (X direction in the figure), and moves the moving mechanism 50. moves the gas leak detector 11 in a direction perpendicular to the expansion direction (Y direction in the figure).

Also, the gas leak detection device 200 can be used to implement a gas leak detection method that includes a placement step, a movement step, and a presentation step, similarly to the gas leak detection device 10.

Also in the gas leak detection device 200, as described above, the laser irradiated from the laser irradiation unit 20 is expanded in the expansion direction (X direction in the figure), and the moving mechanism 50 moves the gas leak detector 11 in the orthogonal direction (the X direction in the figure). Since the sensor is moved in the Y direction in the figure, the detection range (indicated by the two-dot chain line in the figure) is formed in a band shape (see FIG. 7). Therefore, compared to the first configuration (see FIG. 5) and the second configuration (see FIG. 6), the detection range in which gas leakage can be detected can be widened.

Furthermore, in this embodiment, since the laser is expanded by the lens 230, which is an optical element, the laser can be expanded without being driven.

The present invention is not limited to the embodiments described above, and various modifications, changes, and improvements can be made without departing from the spirit thereof. For example, the modified examples shown above may be configured by combining a plurality of them as appropriate.

10 Gas leak detection device 11 Gas leak detector 20 Laser irradiation part (an example of irradiation part)
30 Scanning section (example of extension section)
32 Polygon mirror 40 Laser light receiving part (an example of a light receiving part)
50 Moving mechanism (an example of a moving part)
200 Gas leak detection device 230 Plano-concave cylindrical lens (an example of an optical element)

Claims (3)

an irradiation unit that irradiates a laser toward an irradiation target ;
an expansion part that expands the laser irradiated from the irradiation part in one direction;
a light receiving section that receives the laser expanded by the expansion section and reflected from the irradiation target ;
a moving unit that moves the irradiating unit, the expanding unit, and the light receiving unit in a direction perpendicular to the one direction,
The expansion part is a polygon mirror that expands in the one direction by scanning the laser from the irradiation part along the one direction while rotating,
The light receiving unit directly receives the laser beam expanded in the one direction by the polygon mirror and reflected from the irradiation target.
Gas leak detection device. The rotation axis direction of the polygon mirror is along the orthogonal direction.
The gas leak detection device according to claim 1. an irradiation unit that irradiates a laser toward an irradiation target ;
an expansion part that expands the laser irradiated from the irradiation part in one direction;
a light receiving section that receives the laser that is expanded by the expansion section and reflected from the irradiation target ;
The expansion part is a polygon mirror that expands in the one direction by scanning the laser from the irradiation part along the one direction while rotating,
The light receiving unit includes a gas leak detector that directly receives the laser beam expanded in the one direction by the polygon mirror and reflected from the irradiation target.
detecting gas leakage by moving in a direction perpendicular to the one direction ;
Gas leak detection method.