JP2003139790A - Optical current direction sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a strong and inexpensive optical current direction sensor not affected by the circumferential condition, easily performing the multi-point observation, and not needing a power source at all. SOLUTION: A rotatable shaft 20 is mounted on a non-magnetic pipe 17 mounted in a main body cylinder 10 in a state of being projected from a lower end of the non-magnetic pipe 17, a rudder 24 directed in the water current direction is mounted on a lower end of the shaft 20, an internal magnet 30 is mounted on the shaft 20 in the non-magnetic pipe 17, a pair of distortion detecting plates 26, 27 are mounted in a state of being suspended down along an outer side face of the non-magnetic pipe 17 from upper end both sides of the non-magnetic pipe 17, external magnets 28, 29 are mounted oppositely to the internal magnet 30 at a non-magnetic pipe 17 side of a lower part of the distortion detecting plates 26, 27, and FBGs 31, 32 connected to the optical fiber 33 and respectively outputting the different wavelengths from the light emitted from the optical fiber 33 by the distortion, are integrally mounted on the distortion detecting plates 26, 27.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow direction sensor for constantly monitoring the direction of a river water flow, and more particularly to an optical flow direction sensor for monitoring a flow direction using an optical fiber.

[0002]

2. Description of the Related Art Conventionally, as a method of detecting the direction of flowing water in a river, a method of directly emitting a radio wave on the surface of the flow and monitoring the flow direction by the Doppler effect of the reflected wave, a TV camera for moving fine particles contained in the flowing water There is a method in which the image is captured as an image, the locus is directly monitored, and calculation is performed.

[0003]

However, the former method of monitoring the flow direction of a river or the like by using an electric sensor for radio waves, etc., is an electric method, so that it is not easy to secure a power source, and a plurality of locations are required. When monitoring at the same time, a device such as a transmission device is required, which is not suitable for multiple points. In addition, in bad weather such as rainfall, the radio waves may become unstable and reliable monitoring may not be possible. Furthermore, if the sensor is left unattended for a long period of time, the output will not be stable if the input / output section of the sensor becomes extremely dirty, and the sensor itself is expensive and maintenance after installation is not easy.

In the latter method in which a CCD camera is used to monitor the flow direction by the movement trajectory of fine particles contained in running water, since the operator inputs the movement trajectory of the fine particles, in the case of high water flow, the movement speed of the fine particles is input fast. Is difficult. In addition, it is impossible to monitor when the water surface is stagnant and the flow is low,
There is also a problem that the lens portion of the camera becomes dirty and a clear image cannot be taken if left unattended for a long period of time. Moreover, the maintenance and securing of the power source are not easy, and it is systematically impossible to perform multipoint continuous monitoring.

Therefore, an object of the present invention is to solve the above-mentioned problems, to easily monitor multiple points without being affected by the surrounding environment, to require no power source at all, and to be robust and inexpensive. To provide.

[0006]

In order to achieve the above object, the invention of claim 1 is such that a rotatable shaft is attached to a non-magnetic pipe provided in a main body cylinder from a lower end of the non-magnetic pipe. A rudder is provided at the lower end of the shaft so as to project in the water flow direction, an internal magnet is provided on the shaft in the non-magnetic pipe, and both ends of the non-magnetic pipe are at the upper end.
A pair of strain detection plates are provided so as to hang down along the outer surface of the non-magnetic pipe, and an external magnet is provided facing the internal magnet on the non-magnetic pipe side below the strain detection plate to detect the strain. It is an optical flow direction sensor in which an FBG that is connected to an optical fiber and that outputs different wavelengths from light incident from the optical fiber due to strain is integrally provided on a plate.

According to the second aspect of the present invention, the temperature correction of the two strain detection plates is performed based on the change amount of the output wavelength of the FBG on the side of the strain detection plate, which is changed depending on the flow direction, from the output wavelength of the FBG on the side of the other strain detection plate. The optical flow direction sensor according to claim 1, wherein the change amount is subtracted.

According to a third aspect of the present invention, in the FBG, a grating portion for changing the wavelength and outputting the light from the optical fiber is formed in the optical fiber provided integrally with the strain detecting plate. 2. The optical flow direction sensor according to claim 1, wherein the strain detecting plate is integrated with the strain detecting plate with a slight amount of tension applied.

According to a fourth aspect of the present invention, a plurality of strain detecting plates are provided on the non-magnetic pipe, and external magnets are provided on these strain detecting plates. The rotary motion of the rudder accompanying the above FB
The optical flow direction sensor according to claim 1, wherein the optical flow direction sensor detects the change in the output wavelength of G.

The invention of claim 5 relates to an optical fiber according to claim 1.
An optical flow direction sensor is characterized in that a plurality of the described optical flow direction sensors are connected in series.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows an FBG (Fiber Bragg Grating).
It is sectional drawing which shows the internal structure of a utilization optical type flow direction sensor.

In FIG. 1, reference numeral 10 designates a main body cylinder, an upper flange 11 is attached to an upper part thereof, a lower flange 12 is attached to a lower part thereof with bolts 13 and 14, and a space between the main body cylinder 10 and the upper and lower flanges 11 and 12 is O. Sealed with rings 15 and 16.

The non-magnetic pipe 1 extends through the lower flange 12 from the inside of the body cylinder 10 to below the lower flange 12.
7 is provided. A shaft 20 is rotatably provided in the non-magnetic pipe 17 located in the main body cylinder 10 via upper and lower bearings 18 and 19. Upper and lower bearing 1
8 and 19 are fixed in the nonmagnetic pipe 17 by stop rings 21 and 22, respectively.

The shaft 20 extends downward from a collar 23 provided at the lower end of the non-magnetic pipe 17, and the rudder 2 is provided below the collar 23.
4 are provided. The rudder 24 is formed in the same shape as the rudder shape of a plastic ship or the like.

At the upper end of the non-magnetic pipe 17 in the body tube 10, the mounting plate 2 is provided so as to project outward in the radial direction of the body tube 10.
5 is provided, and the strain detecting plates 2 are provided on both sides of the mounting plate 25.
6, 27 are supported in a cantilever manner and are provided so as to hang along the side surface of the non-magnetic pipe 17, and the external magnets are provided at the lower ends of the strain detecting plates 26, 27 facing the non-magnetic pipe 17. 28 and 29 are provided. The strain detection plates 26 and 27 are preferably made of a material such as SUS spring steel, super invar material, etc., which has a small shrinkage rate due to temperature changes.

An internal magnet 30 is attached to the shaft 20 so as to face the positions of the external magnets 28 and 29. The inner magnet 30 and the outer magnets 28 and 29 may have different polarities or may have the same polarities. The permanent magnets used for the internal magnet 30 and the external magnets 28 and 29 are most preferably magnet density of about 2000 to 2500 gauss.

FBGs 31 and 32 are attached to the strain detecting plates 26 and 27 integrally with the strain detecting plates 26 and 27.

First, the optical fiber 33 connected to the flow direction measuring device (not shown) is formed into a loop, and the upper flange 11 is formed.
Further, the optical fiber 33A is introduced into the main body cylinder 10 and the upstream optical fiber 33A of the flow direction measuring device is connected to the strain detecting plate 2 for detecting the direction of the outside water.
7 is integrated into a strain measurement optical fiber section 33D, and the strain measurement optical fiber section 33D is connected to the connection optical fiber 33C.
Is integrated with the strain detecting plate 28 for detecting the direction of the inner water via an optical fiber 33U for strain measurement.
From U, the downstream optical fiber 33B of the flow direction measuring device is extended to the outside of the main body cylinder 10 through the upper flange 11, and the downstream optical fiber 33B is sequentially connected to other optical flow direction sensors in the same manner, and multipoint An optical fiber 33 is provided so that the flow direction can be measured at.

The FBGs 31 and 32 are the strain detection plates 26 and 2 respectively.
Optical fiber 33U, 33D for strain measurement integrally provided in 7
Grating portions 34U and 34D having different diffraction wavelengths
Is formed and formed.

2 (a) to 2 (c) show the strain detection plate 2
2A and 2B show the details of mounting the FBGs 31 and 32 on the 6 and 27. FIG. 2A is a front view, FIG. 2B is a side view, and FIG.
(C) is a sectional view.

The FBGs 31 and 32 have strain detection plates 26 and 27 formed of SUS spring steel or the like, and a grating portion 34.
It is formed by integrally attaching the strain measurement optical fiber portions 33U and 33D coated with PI (polyimide) on which U and 34D are formed, with an adhesive (epotic; trade name) 35. The grating portions 34U and 34D are formed so that the output wavelengths due to diffraction differ. In addition, the strain detection plate 26,
When integrating 27 and FBGs 31 and 32, FB
By integrating the G31 and 32 with a slight amount of tension, it is possible to detect the bending of the minute strain detection plates 26 and 27 with high sensitivity.

Next, the operation of the present invention will be described.

The main body tube 10 is installed near the water surface of a river for measuring water flow, and the rudder 24 is attached so as to be immersed in the water surface.

As shown in FIG. 3 (a), the rudder 24 is designed so that when the water flow is in the inward direction (flow from upstream to downstream),
The rudder 24 is rotating to indicate the inward water direction, and the shaft 20,
The internal magnet 30 is also in a position that indicates the direction of internal water.

In this state, the external magnet 28 of the external magnets 28 and 29, which indicates the direction of the internal water, and the internal magnet 30 attract each other, so that the strain detecting plate 26 is deformed so as to contact the nonmagnetic pipe 17. To do.

When the water flow changes from the inner water direction to the outer water direction, as shown in FIG.
Rotates in the direction of outside water, and at the same time, the inner magnet 30 also points in the direction of outside water. Then, similarly to the detection of the inward water direction, the external magnets 29 indicating the outward water direction attract each other, and the strain detecting plate 2 is detected.
7 deforms so as to contact the non-magnetic pipe 17.

Light is incident on the optical fiber 33 from a flow direction measuring device (not shown), and the strain detecting plate 2
Due to the deformation of Nos. 6 and 27, the FBGs 31 and 32 cause reflection due to diffraction, and the output wavelength of the reflected light changes. Therefore, by measuring this change with the flow direction measuring device, the rudder 24 is directed toward the inward direction or the outward direction. It is possible to determine whether it is the water direction or another direction (a state where the water flow is stagnant).

In this case, the flexure amount of the strain detecting plates 26 and 27 at the time of bending is 1.5 to 2.0 in terms of the FBG output wavelength change amount.
It is desirable to set the thickness to nm in consideration of temperature and wavelength separation in the flow direction, and most desirable to perform the reproducibility of the strain detection plates 26 and 27 with high accuracy.

FIG. 4 is a diagram for explaining the flow direction determination by the wavelength change of the FBG-use optical flow direction sensor of the present invention.

In FIG. 4, A is when the water flow is stagnant, B is when the water flow is in the inward direction (upstream to downstream direction), and C is when the water flow is in the outflow direction (downstream to upstream direction). The orientation of the rudder 24 of the FBG-using optical flow direction sensor at that time is also shown.

First, as described above, the FB for detecting the inward water direction
The G31 and the FBG 32 for detecting the outside water direction are formed so as to have different output wavelengths, and the direction of the water flow is discriminated from the change in the two wavelengths.

That is, in FIG. 4, a shows a wavelength change by the FBG 31 for detecting the inward water direction, and b shows a wavelength change by the FBG 32 for detecting the outer water direction, when the water flow is stagnant. In (A), since the rudder 24 does not have a water flow direction as shown in the figure, it does not show directionality, and when the water flow is in the inward water direction (flow from right to left in the figure), the rudder 24 is , Its tail faces downstream (see FIG. 3 (a)),
The inner magnet 30 and the outer magnet 28 on the inner water side attract each other to bend the strain detection plate 26, whereby the output wavelength changes in the FBG 31. Also, when the water flow is in the direction of the outside water (flow from left to right in the figure) (C), the tail of the rudder 24 faces the upstream direction (see FIG. 3 (b)).
And the external magnet 29 on the outside water side attract each other, and the strain detection plate 27
Is bent, so that the output wavelength changes in the FBG 32.

In this way, the output wavelength changes a and b of the FBGs 31 and 32 are detected by the flow direction measuring device, and by processing this signal, the flow direction of the river water flow can be easily detected by the presence or absence of both wavelength changes. be able to.

Further, the strain detecting plates 26 and 27 linearly expand due to the temperature change, and this affects the output wavelength change of the FBGs 31 and 32, so that the temperature is corrected. This temperature correction is performed by the strain detection plate 26 (or 27) that changes depending on the flow direction.
This is done by subtracting the amount of change in the output wavelength of the other distortion detection plate 27 (or 26) from the amount of change in the output wavelength of the other.

In the above embodiment, the strain detecting plates 26 and 27 and the FBG 3 are located upstream and downstream in the water flow direction.
Although the example in which 1, 32 are provided has been described, this distortion detection plate 2
6, 27 and the strain detection plate and FBG at the position rotated 90 degrees
By providing the above, it is possible to detect the direction of the rudder when the water flow in FIG. 4 is stagnant (A) and also to detect the state of rotation when the water flow is spiral and the rudder 24 rotates. It is possible.

As described above, according to the optical flow direction detection sensor of the present invention, the flow direction of a river or the like can be detected accurately without a power source, and by connecting the optical flow direction detection sensors in series to the optical fiber, Multi-point measurement of river water flow is also possible.
The optical flow direction detection sensor has an outer diameter of about 100 mm, a height of 300 mm, and a weight of about 5 k
It is lightweight and compact, and can be provided locally.

[0038]

In summary, according to the present invention, it is possible to provide an inexpensive optical flow direction sensor which is not affected by the surrounding environment and can easily be multi-pointed and which requires no power source.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a diagram showing details of FBG attachment to the strain detection plate of FIG.

FIG. 3 is a diagram illustrating a rudder direction with respect to a water flow in the present invention.

FIG. 4 is a diagram illustrating flow direction determination based on a change in the output wavelength of an FBG in the present invention.

[Explanation of symbols]

10 Body tube 17 Non-magnetic pipe 20 shaft 24 rudder 26,27 Strain detection plate 28,29 External magnet 30 internal magnet 31,32 FBG 33 optical fiber

Continued front page    (72) Inventor Hiroshi Kamoshida             1-6-1, Otemachi, Chiyoda-ku, Tokyo             Standing Wire Co., Ltd. F-term (reference) 2F034 AA04 DB05 DB14

Claims (5)

[Claims] 1. A non-magnetic pipe provided in a main body cylinder is provided with a rotatable shaft projecting from a lower end of the non-magnetic pipe, and a lower end of the shaft is provided with a rudder directed in a water flow direction. An internal magnet is provided on the shaft in the non-magnetic material pipe, and a pair of strain detection plates are provided so as to hang down from the upper end sides of the non-magnetic material pipe along the outer surface of the non-magnetic material pipe. On the non-magnetic pipe side,
An external magnet is provided so as to face the internal magnet, and an FBG that is connected to an optical fiber and that outputs different wavelengths from light incident from the optical fiber due to strain is integrally provided on the distortion detection plate. A characteristic optical flow direction sensor. 2. The temperature correction of the two strain detection plates is performed by subtracting the amount of change in the output wavelength of the FBG on the other strain detection plate side from the amount of change in the output wavelength of the FBG on the strain detection plate side that has changed depending on the flow direction. The optical flow direction sensor according to claim 1, which is performed by the above. 3. The FBG comprises an optical fiber provided integrally with the strain detection plate and a grating portion for outputting light from the optical fiber with a wavelength changed, and the optical fiber of the FBG is integrated with the strain detection plate. 2. The optical flow direction sensor according to claim 1, wherein the optical flow direction sensor is integrated in a state where a slight amount of tension is applied during the process. 4. A non-magnetic pipe is provided with a plurality of strain detection plates, each strain detection plate is provided with an external magnet, and each strain detection plate is integrally provided with an FBG.
The optical flow direction sensor according to claim 1, wherein the rotational movement of the rudder associated with the water flow is detected from a change in the output wavelength of each FBG. 5. An optical flow direction sensor comprising a plurality of optical flow direction sensors according to claim 1 connected in series to an optical fiber.