JP2002054974A - Water level measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly reliable water level measuring device receiving no influence of induction of thunder or a high voltage electric wire, dispensing with a power source of a sensor, superior in corrosion resistance and causing little failure in an outdoor severe environment. SOLUTION: This water level measuring device is provided with an inner tube 3 being a cylindrical part deformed by water pressure, an optical fiber 4 arranged in a spiral shape in the inner tube 3, a strain distribution measuring apparatus 7 for measuring the strain distribution of the optical fiber 4 and a computer 8 for determining a water level from the strain distribution.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is installed in, for example, rivers, lakes and marshes, ground, liquid tanks, etc., and its water level (liquid level)
The present invention relates to a water level measuring device for measuring water.

[0002]

2. Description of the Related Art In a conventional water level measuring device which is installed in a river, a lake, a ground, a liquid tank or the like and measures the water level, a sensor section (that is, a water level measuring section, a water level meter) is provided with a strain resistance meter or the like. Electrical parts and movable parts such as floats have been used.

[0003]

In a conventional water level measuring apparatus using an electric component such as a strain resistance meter in the sensor section, the conventional water level measuring apparatus is affected by the induction of lightning, high-voltage wires, etc., and requires a power supply for the sensor. There was a problem of poor corrosion resistance.

Further, in the conventional water level measuring device having a movable part such as a float in the sensor part, a failure easily occurs in a severe environment such as outdoors, and there is a problem of low reliability.

An object of the present invention is to provide a sensor which is not affected by lightning, high-voltage electric wires, and the like, does not require a power supply for a sensor, has excellent corrosion resistance,
It is still another object of the present invention to provide a highly reliable water level measuring device that is less likely to fail in a severe environment such as outdoors.

[0006]

In order to solve the above-mentioned problems, a water level measuring apparatus according to the present invention comprises: a tubular part deformed by water pressure; an optical fiber spirally provided on the tubular part;
A water level measuring means for measuring a strain distribution of the optical fiber and obtaining a water level from the strain distribution.

In the water level measuring device of the present invention, since no electric parts are used for the sensor section, it is not affected by the induction of lightning, high-voltage wires, etc., does not require a power supply for the sensor, is excellent in corrosion resistance, and has a high sensor resistance. Since there is no movable part in the part, a failure hardly occurs in a severe environment such as outdoors, and a highly reliable water level measuring device can be realized.

[0008]

Embodiments of the present invention will be described below in detail with reference to the drawings. In the drawings described below, components having the same functions are denoted by the same reference numerals, and repeated description thereof will be omitted.

FIG. 1 is a diagram showing a configuration of a water level measuring device according to an embodiment of the present invention.

1 is a water level measuring device, 2 is a water level gauge (that is, a sensor, a water level measuring unit), 3 is an inner tube which is a cylindrical part made of a material having a large elastic coefficient such as rubber which is deformed by water pressure, and 4 is An optical fiber spirally provided on, for example, the outer surface of the inner tube 3, an outer tube 5 made of, for example, plastic or the like for protecting the inner tube 3 and the optical fiber 4, and 6 provided on the bottom surface of the inner tube 3. 7 is a filter for preventing foreign substances other than water and liquid to be measured from entering the optical fiber.
Strain distribution measuring instrument for measuring the strain distribution of, for example, B-
OTDR (Brillouin Optical-fiber Time Domain Refl
Reference numeral 8 denotes a computer such as a personal computer which calculates and calculates a water level based on the data of the strain distribution measured by the strain distribution measuring device 7.

The water level measuring apparatus 1 according to the present embodiment is installed in, for example, a river, a lake, a ground, a liquid tank, or the like, and measures the water level (liquid level). The water level measuring device 1 according to the present embodiment includes an inner pipe 3 which is a cylindrical part deformed by water pressure,
An optical fiber 4 spirally provided in the inner tube 3;
And a water level measuring means for measuring a water level from the strain distribution. In the present embodiment, the water level measuring means calculates and calculates the water level based on the strain distribution measuring device 7 for measuring the strain distribution of the optical fiber 4 and the data of the strain distribution measured by the strain distribution measuring device 7. It comprises a computer 8 such as a personal computer.

FIG. 2 is a diagram of the water level measuring device of the present embodiment showing the configuration of the strain distribution measuring device 7 of FIG.

7 is a strain distribution measuring instrument, for example, B-OTD
R and 21 are light sources, 22 is a signal light, 23 is an optical frequency converter, 24 is an optical pulse modulator, 25 is an optical pulse as incident light, 26 is reference light, 27 is backscattered light, and 28 is coherent light reception. , 8 is a computer, 2, 2 ', ... is a water level gauge, 4
Is an optical fiber.

The signal light (laser light) 22 and the reference light 26 are output from the light source 21 of the strain distribution measuring device 7 and the signal light 22
Is converted into an optical frequency by an optical frequency converter 23, an optical pulse 25 is generated by an optical pulse modulator 24, and the water level meter 2,
2 ', ... The backscattered light 27 returned from the water level meters 2, 2 ',... Is received by the coherent light receiver 28, and the strain distribution is measured by the coherent light receiver 28. An electric signal indicating the strain distribution required for the water level calculation is input to the computer 8, and the water level is calculated and obtained.

An OTDR (Optical-fiber Time Dom)
In the ain Reflectometer method, reflected light or backscattered light of an incident pulse is received, and the break point, strain distribution, temperature distribution, and the like of the optical fiber can be obtained. In the B-OTDR according to the present embodiment, Brillouin (Bril
louin) Use scattered light.

As shown in FIGS. 1 and 2, one end of the optical fiber 4 wound around the inner tube 3 is connected to a strain distribution measuring device 7. The strain distribution measuring device 7 composed of the B-OTDR detects the frequency shift amount of the Brillouin scattered light corresponding to the distortion of the optical fiber 4 of the optical pulse 25 (FIG. 2) incident on the optical fiber 4, thereby detecting the optical fiber. 4 is measured. Further, the position where the distortion of the optical fiber 4 occurs is measured by the time from the incidence of the optical pulse 25 to the arrival of the scattered light 28 and the length of the optical fiber 4.

FIGS. 3A and 3B are views showing the deformation of the inner tube and the optical fiber in the present embodiment.

When the water level 9 inside the inner pipe 3 shown in FIG. 3A changes at the water level measuring place, as shown in FIG. 3B, the inner pipe 3 made of a material having a large elastic coefficient such as rubber is used. The inner pipe 3 is deformed according to the external pressure (water pressure), the distribution of the water pressure acting on the inner wall of the inner pipe 3 changes, and the inner pipe 3 is deformed. At this time, a strain occurs in the optical fiber 4 wound around the inner tube 3, and the strain distribution also changes. In the bulging portion of the inner tube 3, tensile strain is generated in the optical fiber 4, and in the concave portion of the inner tube 3, compressive strain is generated. The scattered light 27 at this time
By detecting the frequency shift amount (FIG. 2), the amount of strain generated in the spirally wound optical fiber 4 is measured, and by measuring the change in strain distribution, the water level 9 is indirectly determined from the strain distribution pattern. Measurement.

FIG. 4 is a view showing a state where the water level measuring device 1 of the present embodiment is installed in a river.

41 is a river embankment, 42 is a river surface, 43 is a groundwater surface, 44 is a groundwater level, 4 is an optical fiber,
Reference numerals 2 ', 2 ",... Indicate water level gauges.

Here, as an example of installation of the water level gauge 2 according to the present embodiment, a groundwater level 44 in a river embankment 41 is measured. The water level meters 2, 2 ', 2 ",...
Are installed continuously by one optical fiber 4, the groundwater level 44 at each point can be measured.

In the water level measuring apparatus 1 according to the present embodiment, since no electric parts are used for the water level meter (sensor section) 2,
It is not affected by the induction of high-voltage wires, etc., does not require a sensor power supply, has excellent corrosion resistance, and has no moving parts in the sensor. A measuring device can be realized.

As a prior art similar to the present invention, there is an apparatus described in Japanese Patent Application Laid-Open No. 5-180684 (hereinafter referred to as a conventional apparatus). However, the configuration of the water level measuring device 1 of the present embodiment is clearly different from that of the conventional device.
First, the arrangement of the optical fiber 4 of the water level gauge (sensor unit) 2 is as follows.
In the device 1 of the present embodiment, the inner tube 3 is spirally wound. On the other hand, in the conventional device, the optical fibers are arranged in the vertical direction, and are fixed pointwise by stoppers.
In addition, in the device 1 of the present invention, the position where the strain occurs is continuous in the spiral optical fiber 4. On the other hand, in the conventional device, a stoppage of the optical fiber arranged in the vertical direction or a point occurs at the position of the pressure conversion material.

Although the present invention has been specifically described based on the embodiments, the present invention is not limited to the above-described embodiments, and it is needless to say that various modifications can be made without departing from the gist of the present invention. It is. For example, in the water level measuring device 1 of the above embodiment, the optical fiber 4 is provided spirally on the outer wall surface of the inner tube 3, but may be provided spirally on the inner wall surface or inside of the inner tube 3.

[0025]

As described above, according to the present invention,
It is not affected by the induction of lightning, high-voltage electric wires, etc., does not require a sensor power supply, has excellent corrosion resistance, and is hard to cause failures in harsh environments such as outdoors, providing a highly reliable water level measurement device. it can.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a water level measuring device 1 according to an embodiment of the present invention.

FIG. 2 is a diagram of a water level measuring device according to the present embodiment, showing a configuration of a strain distribution measuring device 7 of FIG. 1;

FIGS. 3A and 3B are inner tubes 3 according to the present embodiment.
FIG. 3 is a diagram illustrating a state of deformation of an optical fiber 4.

FIG. 4 is a diagram showing a state where the water level measuring device 1 of the present embodiment is installed in a river.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Water level measuring device, 2, 2 ', 2 "... Water level meter, 3 ... Inner tube (cylindrical part), 4 ... Optical fiber, 5 ... Outer tube, 6 ... Filter, 7 ... Strain distribution measuring device, 8 ... Calculator, 9 ... water level, 2
DESCRIPTION OF SYMBOLS 1 ... Light source, 22 ... Signal light, 23 ... Optical frequency converter, 24
... optical pulse modulator, 25 ... optical pulse, 26 ... reference light, 2
7 ... backscattered light, 28 ... coherent light receiver, 41 ...
River embankment, 42 ... river water surface, 43 ... groundwater surface, 44 ... groundwater level.

 ────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Hiroshi Komatsu 2-3-1 Otemachi, Chiyoda-ku, Tokyo F-term in Nippon Telegraph and Telephone Corporation (reference) 2F014 AA12 AA16 AB02 BA10 FA01

Claims (1)

[Claims] 1. A tubular part which is deformed by water pressure, an optical fiber spirally provided on the tubular part, and a water level measuring means for measuring a strain distribution of the optical fiber and obtaining a water level from the strain distribution. A water level measuring device, comprising: