JP2001188021A - Optical water level detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect whether or not a water level exceeds a specific value with simple constitution by reducing mechanical movable parts. SOLUTION: This detector is equipped with a float 20 which floats on water whose level should be detected, an up/down moving unit 13 which is able to move up and down in a detection cell 10 by being driven by the float 20, an input optical fiber 11 which makes detection light enter the detection cell 10, and an output optical fiber 12 that the light projected from the input optical fiber 11 through the up/down moving unit 13 enter in the detection cell 10. The up/down moving unit 13 is equipped with a 1st intermediate optical fiber 15 which is aligned with the input optical fiber 11 and output optical fiber 15 when the water level is below the set value and the up/down moving unit 13 is at its lower dead point and a 2nd intermediate optical fiber 16 which is aligned with the input optical fiber 11 and output optical fiber 12 when the water level is above the set value and the up/down moving unit 13 is at its upper dead point and also has FBG 19.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention uses a fiber Bragg grating (hereinafter referred to as "FBG") to detect the water level and whether or not the water pressure according to the water level is higher than a certain value. The present invention relates to a water level detector, for example, to an optical water level detector for detecting a water level and a water pressure of sewage and performing optimal flow control.

[0002]

2. Description of the Related Art
Known sewage water level detectors include those that mechanically and electrically detect the position of a float in sewage, and those that optically detect the water level itself and convert it to an electric signal.
However, these water level detectors have various problems, such as many mechanically movable parts, causing a failure, and the necessity of installing a battery near the detector in order to secure the power of the electric circuit.

On the other hand, for example, as disclosed in Japanese Patent Application Laid-Open Nos. 11-51744 and 11-83601, a change in the buoyancy of a float is converted into distortion of a tensile strength member, and this distortion is converted to FBG.
There is known a liquid level gauge which detects the liquid level and measures the liquid level. Here, as is well known, the FBG is a region where the refractive index of the core of the optical fiber periodically changes along the optical axis, and narrow-band light centered on a specific wavelength according to the refractive index. Has reflective properties. Also, since the refractive index of the core changes according to the strain applied to the optical fiber and the ambient temperature, the wavelength of the reflected light from the FBG is detected to detect the presence or absence of the strain or temperature change, its magnitude, etc. can do. The liquid level meter described in the above-mentioned Japanese Patent Application Laid-Open No. 11-51744 is an application of the principle of strain detection by the FBG, but transmits the buoyancy of the float to the tensile strength member, and furthermore, transmits the strain of the tensile strength body to FBG. Since the structure transmits the force, a loss of force easily occurs and there is a problem in measurement accuracy, and the structure is generally complicated.

Accordingly, an object of the present invention is to provide an optical water level detector capable of reliably detecting whether or not a water level and a water pressure have exceeded a certain value by a simple structure having few mechanically movable parts. .

[0005]

Means for Solving the Problems To solve the above-mentioned problems, an invention according to claim 1 comprises a float floating on water whose water level is to be detected, and an up-down movable which can move up and down in a detection cell following the float. Moving unit, an input optical fiber for inputting detection light into the detection cell, and an output optical fiber for receiving light emitted from the input optical fiber through the vertical movement unit from the input optical fiber inside the detection cell; A first intermediate optical fiber positioned in line with the input optical fiber and the output optical fiber when the water level is equal to or lower than the set value and the vertical motion unit is at the bottom dead center;
A second intermediate optical fiber that is aligned with the input optical fiber and the output optical fiber when the water level is equal to or higher than the set value and the vertical movement unit is at the top dead center, and that has an optical fiber Bragg grating; It is provided with.

According to a second aspect of the present invention, there is provided a float which floats on water whose water level is to be detected, and an optical fiber Bragg diffraction grating is provided in a part penetrating the detection cell, and the inside of the detection cell is driven by the float. An optical fiber capable of moving up and down and receiving the detection light, a first magnet attached to the optical fiber, a second magnet fixed inside the detection cell and adsorbable to the first magnet, Wherein the optical fiber inside the detection cell is at a position determined by the attraction of the first and second magnets when the water level is equal to or lower than a set value, and the attraction with the second magnet is released when the water level is equal to or higher than the set value. The first magnet is located at a position determined by the top dead center.

According to a third aspect of the present invention, there is provided a float floating on the water whose water level is to be detected, an arm rotatably supporting the float, a fulcrum of the arm provided in the detection cell, and a fulcrum of the fulcrum. An optical fiber having an optical fiber Bragg diffraction grating arranged so as to surround and having one end fixed to the arm, and the other end fixed inside the detection cell, and having detection light incident thereon, The optical fiber is characterized in that one end fixed to the arm is movable in accordance with the vertical movement of the float accompanying a change in the water level.

According to a fourth aspect of the present invention, there is provided a float floating on the water whose water level is to be detected, an arm rotatably supporting the float, a fulcrum of the arm provided in the detection cell, and a fulcrum. An optical fiber, one end of which is fixed to the arm end opposite to the float through which the detection light is incident, and the optical fiber is attached to the arm in accordance with the vertical movement of the float accompanying a change in water level. The fixed one end is movable.

According to a fifth aspect of the present invention, there is provided an airtight detection cell having a diaphragm responsive to a water pressure according to a water level;
An optical fiber that penetrates through the thickness of the diaphragm, is integrated with the diaphragm, receives detection light, and has an optical fiber Bragg diffraction grating.

According to a sixth aspect of the present invention, there is provided an airtight detection cell having a diaphragm responsive to a water pressure corresponding to a water level;
Suction and suction are released so as to penetrate the inside of the detection cell and receive the detection light and have an optical fiber Bragg diffraction grating, and to move the optical fiber in the detection cell according to a change in water pressure. And a pair of magnets.

According to a seventh aspect of the present invention, there is provided a pressure receiving portion which is deformed in response to a water pressure corresponding to a water level, has a plurality of cut portions integrally fixed to the pressure receiving portion, and has a plurality of cut portions on an optical axis. And an optical fiber on which the cut portion is deformed by deformation of the pressure receiving portion, and air is interposed in the cut portion to form an optical fiber Bragg diffraction grating.

[0012] The invention according to claim 8 is a pressure receiving part which moves in response to a water pressure according to a water level, and which is fixed in a detection cell,
And an optical fiber on which an optical fiber Bragg diffraction grating is formed by a plurality of gaps on the optical axis, and an optical fiber on which detection light is incident, and which is filled so as to fill the gap with the movement of the pressure receiving portion, and is the same as the optical fiber. And a liquid having a refractive index of

According to a ninth aspect of the present invention, there is provided a hollow pressure receiving member which is deformed in response to a water pressure corresponding to a water level, and has an optical fiber Bragg diffraction grating which is tightly wound around an outer peripheral surface of the pressure receiving member. An optical fiber on which detection light is incident,
It is provided with.

According to a tenth aspect of the present invention, the optical fiber on which the optical fiber Bragg diffraction grating is formed, operates when the water level or the water pressure according to the water level becomes a predetermined value or more, to apply a strain to the Bragg diffraction grating and to apply a predetermined voltage to the Bragg diffraction grating. Means for canceling the distortion when the value falls below the value. This invention covers the inventions described in claims 2 to 6 and claim 9.

[0015] The invention according to claim 11 is a float that floats on the water whose water level is to be detected, a bellows that expands and contracts by following the float, a shaft that can move up and down in the detection cell by following the float, A linear guide for guiding the shaft, an arm fixed to the shaft and driven by the shaft, a stopper for restricting vertical movement of the arm, and one end fixed to the arm and the other end fixed to the detection cell And an optical fiber having an optical fiber Bragg diffraction grating formed therein.

According to a twelfth aspect of the present invention, there is provided a float that floats on water whose water level is to be detected, a diaphragm that expands and contracts by following the float, a shaft that can move up and down in the detection cell by following the diaphragm, A linear guide for guiding the shaft, an arm fixed to the shaft and driven by the shaft, a stopper for restricting vertical movement of the arm, and one end fixed to the arm and the other end fixed to the detection cell And an optical fiber having an optical fiber Bragg diffraction grating formed therein,
It is provided with.

According to a thirteenth aspect of the present invention, there is provided a float which floats on the water whose water level is to be detected, a diaphragm which expands and contracts following the float, and which is arranged between the float and the detection cell. A leaf spring disposed below to support the float, a shaft mounted on the diaphragm so as to be movable up and down in the detection cell following the diaphragm, a linear guide for guiding the shaft, An arm fixed to the shaft and driven by the shaft, a stopper for restricting upward movement of the arm, and one end fixed to the arm and the other end fixed to the detection cell, and an optical fiber therein. And an optical fiber on which a Bragg diffraction grating is formed.

According to a fourteenth aspect of the present invention, there is provided a float which floats on water whose water level is to be detected, a detection cell for accommodating the float, a water inlet for introducing water into the float, and a water inlet. An air vent for bleeding air from the detection cell, a pressure receiving portion that comes into contact with the float that has moved upward in the detection cell by buoyancy, a diaphragm to which the pressure receiving portion is fixed, and the diaphragm that follows the diaphragm. A block, an optical fiber having one end fixed to the block, and the other end fixed to the detection cell and having an optical fiber Bragg diffraction grating formed therein,
It is provided with.

According to a fifteenth aspect of the present invention, there is provided a float which floats on water whose water level is to be detected, a first magnetic material incorporated in the float, a detection cell in which the float is accommodated, and A water inlet for introducing air, an air vent for bleeding air in the detection cell when water is introduced, and a partition made of a non-magnetic material that is arranged above the float and does not deform due to pressure An optical fiber in which both ends are fixed to a block on the partition and are arranged in parallel with the partition, and a second magnetic material and an optical fiber Bragg diffraction grating are provided in series between both ends;
A magnetic force acts between the first magnetic material and the second magnetic material by moving the float up and down to move the second magnetic material by a snap action operation, and to apply a load to the optical fiber Bragg diffraction grating. It is intended to be added.

[0020] According to a sixteenth aspect of the present invention, there is provided a float floating in water whose water level is to be detected, a first magnetic material built in the float, a detection cell accommodating the float, and A water inlet for introducing air, an air vent for bleeding air in the detection cell when water is introduced, and a partition made of a non-magnetic material that is arranged above the float and does not deform due to pressure And an optical fiber having one end fixed above the partition wall, and the other end connected to the second magnetic material, and an optical fiber Bragg diffraction grating formed between both ends.
A magnetic force acts between the first magnetic material and the second magnetic material by the vertical movement of the float to move the second magnetic material by a snap action operation, and to apply a load to the optical fiber Bragg diffraction grating. It was done.

According to a seventeenth aspect of the present invention, a substantially cylindrical float floating on the water whose water level is to be detected, a first magnetic material built in the float, a detection cell arranged at the center of the float, An optical fiber having both ends fixed inside the detection cell, and a second magnetic material and an optical fiber Bragg diffraction grating provided in series between both ends; A magnetic force acts between the magnetic material and the second magnetic material to move the second magnetic material by a snap action operation to apply a load to the optical fiber Bragg diffraction grating.

[0022] The invention according to claim 18 is characterized in that a float floating on the water whose water level is to be detected, a first magnetic material built in the float, a detection cell accommodating the float, and When the air is introduced, an air vent for bleeding air in the detection cell, a partition made of a non-magnetic material which is arranged above the float and is not deformed by pressure, and connects the float and the partition An optical fiber in which a telescopic bellows and both ends are fixed to a block on the partition and are arranged in parallel with the partition, and a second magnetic material and an optical fiber Bragg grating are provided in series between both ends. And causing a magnetic force to act between the first magnetic material and the second magnetic material by moving the float up and down to move the second magnetic material by a snap action operation. It is obtained so as to apply a load to the optical fiber Bragg grating.

According to a nineteenth aspect of the present invention, there is provided a float which floats on water whose water level is to be detected, a detection cell incorporated in the float, a bellows having one end connected to the float and the other end fixed. An optical fiber in which one end is fixed to a fixed end in the detection cell, a weight is attached to the other end, and an optical fiber Bragg diffraction grating is formed between the both ends, and the float moves up and down, The vertical position relationship between the fixed end and the weight is reversed to change the load applied to the optical fiber Bragg diffraction grating.

According to a twentieth aspect of the present invention, there is provided a float which floats on water whose water level is to be detected, a stepped shaft which is connected to the float via an arm, and which rotates according to the vertical movement of the float, An optical fiber having one end fixed to the step of the stepped shaft, the other end fixed to the detection cell, and an optical fiber Bragg diffraction grating formed between both ends. The vertical portion moves the step portion to change the load applied to the optical fiber Bragg diffraction grating.

According to a twenty-first aspect of the present invention, a float which floats on water whose water level is to be detected, a shaft which rotates in accordance with the vertical movement of the float, and a spring in the detection cell which corresponds to the rotation of the shaft An arm for holding the first position and the second position by a snap action operation, an arm disposed near the arm, both ends fixed to the detection cell, and an optical fiber Bragg diffraction grating between the both ends. And an optical fiber formed, wherein when the arm is in the first position or the second position, the arm abuts on the optical fiber Bragg grating to apply a load.

According to a twenty-second aspect of the present invention, a float floating on the water whose water level is to be detected is connected to the float via a spherical bearing, and rotates in accordance with the up and down movement of the float. An arm that holds the first position and the second position by a snap action operation by a spring, and is arranged close to the arm;
An optical fiber having both ends fixed to the detection cell and having an optical fiber Bragg diffraction grating formed between both ends, wherein when the arm is at the first position or the second position, the This is to apply a load in contact with the fiber Bragg diffraction grating.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram showing a first embodiment of the present invention. In the figure, reference numeral 10 denotes a detection cell, on both side walls of which an input optical fiber 11 and an output optical fiber 12 are attached in a straight line. In the detection cell 10, a vertically moving unit 13 is disposed between the end faces of the optical fibers 11 and 12.
Float 20 is integrally fixed above connection through connection portion 17 penetrating detection cell 10.

The upper end surface of the vertically moving unit 13 and the detection cell 1
0, and between the lower end surface of the vertical movement unit 13 and the lower surface of the detection cell 10, springs 18 a, 18 b, 18 c, and 18 d are interposed around the extensible rod, respectively. Numeral 13 allows the float 20 to move up and down in the detection cell 10 against the springs 18a and 18b or 18c and 18d as the float 20 moves up and down. In FIG. 1, the vertically moving unit 13 and the float 20 have a structure in which they are close to each other.
It may be connected to the vertical movement unit 13 by a connecting member at a position somewhat away from 0, and in any case, any structure may be used as long as the movement of the float 20 is transmitted to the vertical movement unit 13 without loss.

The vertically moving unit 13 has a structure in which first and second intermediate optical fibers 15 and 16 arranged vertically are integrated by a holding portion 14. Here, an FBG 19 in which the refractive index of the core is periodically changed along the optical axis is formed at the center of the lower intermediate optical fiber 16.
In the illustrated state, the vertical movement unit 13 is located at the bottom dead center, and the upper intermediate optical fiber 15 is aligned with the input optical fiber 11 and the output optical fiber 12. Further, the vertical movement unit 13 is moved up with the rise of the float 20, and when it reaches its top dead center, the lower intermediate optical fiber 16 is arranged so as to be aligned with the input optical fiber 11 and the output optical fiber 12. ing. Although not shown in FIG. 1, the other end of the input optical fiber 11 is branched into two, one of which is provided with a white light source (broadband light source), and the other is provided with a light source from the FBG 19. A wavelength detector for receiving the reflected light and detecting its wavelength is connected.

Next, the operation of this embodiment will be described. Now, when the water level is below the float 20 and no buoyancy acts on the float 20 as shown by W1 in the figure, the spring 1
If the extension tension of the floats 8a and 18b and the weight of the float 20 and the vertical movement unit 13 exceed the extension tension of the springs 18c and 18d and the vertical movement unit 13 is set at the bottom dead center, the input optical fiber The light incident from 11 passes through the upper intermediate optical fiber 15 and enters the output optical fiber 12. Thereafter, when the water level rises and buoyancy acts on the float 20 to reverse the above-mentioned force relationship, the float 20, that is, the vertical movement unit 13 rises, and eventually reaches the top dead center, and the input optical fiber 11 and the lower stage move downward. The intermediate optical fiber 16 and the output optical fiber 12 are arranged on a straight line. The water level at this time is defined as W2. Thereby, the input optical fiber 1
The light incident from 1 reaches the FBG 19 of the intermediate optical fiber 16, and the light of a specific wavelength is reflected and reaches the wavelength detector on the other end of the input optical fiber 11. Therefore, if the wavelength of the reflected light is constantly detected by the wavelength detection unit, it is possible to detect whether or not the water level is equal to or higher than W2.

Next, a second embodiment of the present invention will be described with reference to FIG. In FIG. 2, reference numeral 30 denotes a detection cell, through which an optical fiber 31 penetrates. Reference numeral 32 denotes an FBG formed on the optical fiber 31 in the detection cell 30. The outer peripheral surface of the central portion of the optical fiber 31 is coated with a metal and magnetized to form a first magnet 33. The float 2 is connected to the magnet 33 via the connecting portion 17.
0 is linked. In addition, on the lower surface of the detection cell 30,
A second magnet 34 that is attracted to the first magnet 33 is fixed. Note that, like the embodiment of FIG.
Is branched into two, one of which is provided with a white light source, and the other of which is connected to a wavelength detecting unit which receives reflected light from the FBG 32 and detects its wavelength.

The operation of this embodiment will be described first.
When the water level is below the float 20 as in W1,
The magnets 33 and 34 are assumed to be attracted to each other. As the water level gradually rises, buoyancy begins to act on the float 20, and this buoyancy is the mutual attraction between the magnets 33 and 34 and the magnet 33.
And the sum of the weight of the float 20 and the like, the float 2
0 starts to rise, and accordingly the FBG of the optical fiber 31
The portion 32 is also pulled up. For this reason, FBG3
2 is distorted, and the wavelength of the reflected light changes from the original state.

FIG. 3 schematically shows the spectrum of the wavelength of the reflected light by the FBG, and it is known that the wavelength of the reflected light changes almost linearly when distortion is applied to the FBG. Therefore, if the relationship between the amount of distortion of the FBG 32 due to the displacement of the float 20 and the wavelength of the reflected light is determined in advance, the wavelength of the reflected light is constantly detected by the wavelength detecting unit connected to the optical fiber 31, so that the water level becomes W2. It is possible to detect whether or not the above has occurred.

FIG. 4 is a configuration diagram showing a third embodiment of the present invention. Reference numeral 40 denotes a detection cell, in which a fulcrum 45 is provided.
The arm 49 is attached so as to be rotatable around the center. At the tip of this arm 49, a float 48 located outside the detection cell 40 is attached. The fulcrum 45
The guide disk 43 is provided around the center, and an optical fiber 41 is attached along a part of the outer peripheral surface of the guide disk 43, and one end thereof is fixed to the float 48 side of the arm 49, Is fixed to a block 47 fixed to the detection cell 40, and then connected to a white light source and a wavelength detection unit (not shown). An FBG 42 is formed in the middle of the optical fiber 41. 44
Reference numerals a and 44b denote springs that are disposed at substantially the center and the rear end of the arm 49 via telescopic rods 46a and 46b. 491 and 492 are stoppers for protecting the fiber.

The operation of this embodiment will be described. The water level is below the float 48, as indicated by W1, and the float 4
8, when no buoyancy is applied to the float 48, the tension of the spring 44b is greater than that of the spring 44a,
Is at the bottom dead center. Thereafter, when the water level rises and buoyancy acts on the float 48, this buoyancy acts to reduce the tension of the spring 44 b and the arm 49.
Is rotated. When the arm 49 rotates, the guide disk 43 and the float 4 of the arm 49 are moved from the block 47.
Distortion is applied to the FBG 42 of the optical fiber 41 extending to the side 8, and the wavelength of the reflected light changes. Thereafter, when the water level becomes equal to or higher than W2, the float 48 reaches the top dead center.

Here, the operation in which the float 48 moves between the bottom dead center and the top dead center in accordance with the change in the water level as described above is referred to as a snap action operation for convenience. In the present embodiment, if the relationship between the amount of distortion of the FBG 42 due to the displacement of the float 48 and the wavelength of the reflected light is obtained in advance, the wavelength of the reflected light is always detected by the wavelength detecting unit connected to the optical fiber 41. It can be detected whether or not the water level has become equal to or higher than W2.

In the case where the spring and the extensible rod 46b are removed, and a tension force (a force for pulling up the rear end portion of the arm 49) is always applied to the rear end portion of the arm 49 by the spring 44b, the above-described configuration is employed. Is eliminated, and the water level can be continuously detected from the change in the reflected light wavelength of the FBG 42. In this case, a wavelength detecting unit (reference numeral 30 in FIG.
By providing a threshold value at 0), it is possible to detect whether or not the water level is equal to or higher than the set value, that is, a switch-like detection operation.

FIG. 5 shows a fourth embodiment of the present invention. In the figure, reference numeral 50 denotes a detection cell, in which an arm 53 is attached rotatably around a fulcrum 58. The tip of the arm 53 has a detection cell 50
Is attached. One end of an optical fiber 51 having an FBG 52 is fixed to the other end of the arm 53, and the other end is connected to a white light source and a wavelength detector (not shown). A spring 54a is interposed between the other end of the arm 53 and the lower surface of the detection cell 50 around a telescoping rod 56a, and between the arm 53 on the float 57 side of the fulcrum 58 and the upper surface of the detection cell 50. A spring 54b is interposed around the telescopic rod 56b. Reference numerals 591 and 592 denote stoppers for protecting the fiber.

The operation of this embodiment will be described. The water level is below the float 57 and the float 5
In a state where no buoyancy is applied to 7, the tension of the spring 54b is larger than the tension of the spring 54a, and the float 57 is at the bottom dead center. Thereafter, when the water level rises and buoyancy acts on the float 57, the buoyancy acts to reduce the extension force of the spring 54b and rotates the arm 53. The rotation of the arm 53 causes the optical fiber 51 to move.
Is pulled, the FBG 52 is distorted, and the wavelength of the reflected light changes. For this reason, if the relationship between the amount of distortion of the FBG 52 due to the displacement of the float 57 and the wavelength of the reflected light is determined in advance as in the example of FIG. 4, the wavelength of the reflected light is constantly determined by the wavelength detection unit connected to the optical fiber 51. By detecting, it is possible to detect whether or not the water level has become equal to or higher than W2.

In this embodiment, as in the third embodiment, the spring 54b and the extensible rod 56b are removed, and the spring 54a constantly extends the rear end of the arm 53 (the rear end of the arm 53 is pushed up). Force), the snap action described above is eliminated, and the water level can be continuously detected from a change in the reflected light wavelength of the FBG 42. By providing a threshold value in the wavelength detection unit, it is possible to detect whether or not the water level is equal to or higher than the set value, that is, to perform a switch-like detection operation.

FIG. 6 shows a fifth embodiment of the present invention. This embodiment relates to an optical water level detector for detecting a water pressure corresponding to a water level using FBG, and the same applies to sixth to ninth embodiments described later.
In FIG. 6, reference numeral 60 denotes a hollow disk-shaped detection cell, on the upper surface of which a diaphragm 63 is formed. Also,
The optical fiber 61 is accommodated so as to pass through the inside of the thickness of the diaphragm 63 in the diameter direction. Such a structure can be easily realized by integrally molding the diaphragm 63 and the optical fiber 61 with plastic. Further, an FBG 62 is formed substantially at the center of the optical fiber 61. One end (not shown) of the optical fiber 61 is branched into two, one of which is provided with a white light source, and the other of which is a wavelength for receiving reflected light from the FBG 62 and detecting its wavelength. The detection unit is connected.

Next, the operation of this embodiment will be described. FIG. 6A shows a state in which the water pressure applied to the upper surface of the diaphragm 63 and the internal pressure of the detection cell 60 are balanced.
When the water pressure applied to the diaphragm 63 exceeds the internal pressure, FIG.
As shown in (b), the diaphragm 63 is depressed. FIG.
In the state (b), the optical fiber 61, that is, the FBG 62 is distorted as compared with the state (a), so that the wavelength of the reflected light that enters from one end of the optical fiber 61 and is reflected by the FBG 62 changes. For this reason, when the water pressure exceeds a certain set value, the diaphragm 63 is formed so as to be recessed in a snap action, and if the wavelength of the reflected light at that time is measured in advance, the one end of the optical fiber 61 can be measured. By constantly detecting the reflected light wavelength by the wavelength detection unit, it is possible to easily detect whether or not the water pressure or the water level has exceeded a set value. In addition, a binarized signal detection method is used in which the reflected light wavelength when the diaphragm 63 is continuously (gradually) depressed by water pressure is compared with a threshold value to detect that the water pressure has exceeded a set value. You may take it.

FIG. 7 is a block diagram showing a sixth embodiment of the present invention. In the drawing, reference numeral 70 denotes a hollow disk-shaped detection cell, on the upper surface of which a diaphragm 73 is formed. A magnet 74 is fixed to the inner surface of the diaphragm 73,
A magnet 75 is also fixed to the bottom surface of the detection cell 70 which opposes. The pair of magnets 74 and 75 are normally attracted to each other. Further, an optical fiber 71 is disposed so as to penetrate the diameter portion of the detection cell 70 and the magnet 74, and the FBG is located almost at the center of the optical fiber 71 as described above.
72 are formed. Further, a white light source and a wavelength detector are connected to one end of the optical fiber 71 (not shown).

The operation of this embodiment will be described. The difference from FIG. 6 is that the magnet 74 and the magnet 74, as shown in FIG.
When the water pressure applied to the diaphragm 73 decreases, the diaphragm 73 overcomes the attraction force of the magnets 74 and 75 and returns, as shown in FIG. 7B. Also in this embodiment, since the amount of distortion applied to the FBG 72 and thus the reflected light wavelength changes due to the pressure applied to the diaphragm 73, it is possible to detect whether or not the water pressure or the water level has exceeded a set value by detecting the reflected light wavelength. is there. As described above, it is possible to cope with both the wavelength change due to the snap action deformation of the diaphragm 73 and the wavelength change due to the continuous deformation.

FIG. 8 is a conceptual diagram showing a seventh embodiment of the present invention. In each of the above embodiments, the optical fiber is
In this embodiment, when water pressure is applied to the optical fiber from the pressure receiving section, an FBG is automatically formed, and reflected light of a specific wavelength is generated. In FIG. 8, reference numeral 81 denotes an optical fiber, which is fixed to the surface of a flexible pressure receiving portion 83 such as a diaphragm. At the center of the optical fiber 81, a plurality of cut portions 82a are formed at predetermined intervals. Optical fiber 8
A white light source and a wavelength detection unit are connected to one end (not shown) of the light source 1.

In the operation of this embodiment, the optical fiber 81 is normally linear as shown in FIG. 8A, and light incident from one end of the optical fiber 81 can be emitted from the other end. Now, when the water pressure according to the water level is applied to the pressure receiving portion 83, the pressure receiving portion 83 bends upward. Accordingly, the entire optical fiber 81 fixed to the surface of the pressure receiving portion 83 also curves upward, so that the cut portion 82a is opened and air enters between the cut portions 82a. Looking at the central portion of the optical fiber 81 including the plurality of cut portions 82a, it can be considered as the FBG 82 in which the refractive index of the core changes substantially periodically along the optical axis. That is, the FBG 82 is formed on the optical fiber 81 by the predetermined water pressure, and the light of the specific wavelength out of the light incident from one end of the optical fiber 81 is the FBG 82.
It will be reflected by 82. Therefore, as in the embodiments shown in FIGS. 6 and 7 and the like, it is possible to detect whether or not the water pressure or the water level has exceeded a set value by constantly detecting the reflected light wavelength by the wavelength detection unit.

FIG. 9 shows an eighth embodiment of the present invention. In this embodiment, the optical fiber 9 in the detection cell 90 is
1 is fixed in a state divided by a plurality of gaps 92a, and a lower portion thereof is filled with a matching oil 94 having the same refractive index as that of the optical fiber 91. The matching oil 94 is moved into the gap 92a by the upward movement of the pressure receiving portion 93 to which the water pressure according to the water level is applied.
It is possible to fill in. Note that these gaps 92a
An FBG 92 is formed by the optical fiber 91 having the following. A white light source and a wavelength detector are connected to one end (not shown) of the optical fiber 91.

The operation of this embodiment will be described. When light enters from one end of the optical fiber 91 in the state of FIG.
G92 reflects light of a specific wavelength. When a predetermined water pressure is applied to the pressure receiving portion 93 in this state, the matching oil 94 having the same refractive index as the optical fiber 91 enters the gap 92a and fills the space, so that a state equivalent to one continuous optical fiber 91 is obtained. become. That is, it is possible to detect whether or not the water pressure or the water level has exceeded a set value from the change in the reflected light wavelength depending on the presence or absence of the FBG.

FIG. 10 shows a ninth embodiment of the present invention. In this embodiment, the optical fiber 101 is tightly wound around the outer peripheral surface of a hollow pressure receiving body 103 formed of a substantially barrel-shaped can or the like, and the FBG 102 is mounted on a part of the optical fiber 101 in contact with the outer peripheral surface of the pressure receiving body 103. Is formed.
A white light source and a wavelength detector are connected to one end (not shown) of the optical fiber 101. In addition, the pressure receiver 1
03 can be deformed by water pressure as shown in FIGS. 10 (b) and 10 (c).

In the operation, the inside of the pressure receiving body 103 is maintained at a predetermined pressure, and the pressure receiving body 103 is not deformed when the external water pressure according to the water level is equal to or lower than a set value. However, when the water pressure rises to the set value and the pressure receiver 1
When the internal pressure exceeds 03, the peripheral surface of the pressure receiving body 103 is turned inward and dented by a so-called snap action operation. As a result, the amount of distortion applied to the FBG 102 changes, and the FBG 102
Since the wavelength of the light reflected by 102 also changes, it is possible to detect that the water pressure or the water level has exceeded a set value.
In this embodiment, it is possible to cope with both the wavelength change due to the above-described snap action deformation and the wavelength change due to the continuous deformation.

FIG. 11 shows a tenth embodiment of the present invention. In this embodiment, the buoyancy acting on the float according to the water level change is transmitted to the FBG, and the water level change is detected as a change in the reflection wavelength of the FBG. In this embodiment, a float 105 that moves up and down according to the water level is fixed to one side of the bellows 106, and the other end of the bellows 106 is fixed to the detection cell 104. This bellows 106
Is connected between the detection cell 104 and the float 105 while maintaining airtightness.

One end of a shaft 108 extending in the vertical direction is connected to the float 105, and the linear guide 1
07 restricts the movement other than the vertical movement, the shaft 108 moves up and down in conjunction with the vertical movement of the float 105. An arm 113 is fixed to the other end of the shaft 108 in the horizontal direction.
One of G109 is fixed. An optical fiber 701 at one end of the FBG 109 is fixed to the block 112 fixed to the detection cell 104. In order to restrain the vertical movement of the shaft 108, a lower limit stopper 110
And the upper limit stopper 111 is fixed to the detection cell 104. Further, the optical fiber 701 on the other end side of the FBG 109
Are fixed to a block 112 attached to the detection cell 104.

The FBG 109 is fixed so as to maintain its natural length when the water level is low and buoyancy is not acting on the float 105. In this state, the arm 113 is in contact with the lower limit stopper 110. At this time, the bellows 106 is also set to maintain the natural length.

Next, the operation of this embodiment will be described. In a state where the water level is at the level of W1 and no buoyancy acts on the float 105 as shown in FIG. 11A, the bellows 106 and the FBG 109 maintain their natural lengths.
A force in the direction of gravity is generated by the weight of the float 105 and the shaft 108 on the shaft 108 that moves up and down in conjunction with 05. At this time, the shaft 108 is
The arm 113 is at the lower limit position by contact with the arm 113.

When the water level rises and reaches the position W2 as shown in FIG. 11B, buoyancy is generated in the float 105. The float 105 rises due to the buoyancy, the bellows 106 is contracted, and the shaft 108 and the arm 113 are moved upward so that the FBG 109 is extended. Here, since the upward movement of the shaft 108 is restricted by the upper limit stopper 111, the load applied to the FBG 109 does not change beyond a certain value. When the water level returns to W1 again, the bellows 106 and the FBG 109 exert a force to return to the natural length, and therefore return to the lower limit position where the lower limit stopper and the arm 113 abut.

As described above, the shaft 1 accompanying the change in the water level
08 and the movement of the arm 113, the wavelength of the reflected light of the FBG 109 also changes from a short wavelength to a long wavelength by extending the FBG 109. Therefore, if the wavelength conversion unit constantly detects the reflected light wavelength, the water level or the water pressure Is detected to be equal to or greater than the set value. A feature of this embodiment is that the shaft 108 connected to the float 105
Movement is restricted only by vertical movement by the linear guide 107, so that even if a water flow acts on the float 105 in the horizontal direction, no load is applied to the FBG 119 and the FBG 119 is not easily affected by wavelength detection. is there.

FIG. 12 shows an eleventh embodiment of the present invention. In this embodiment, as in the tenth embodiment, the buoyancy acting on the float due to a change in water level is transmitted to the FBG, and a change in the reflection wavelength is detected. In the present embodiment, the float 115 that moves up and down according to the water level is fixed to the center of the diaphragm 116,
The periphery of 6 is fixed to the bottom of the detection cell 104 using a means for ensuring airtightness such as electron beam welding. A shaft 117 is connected to the diaphragm 116 in the vertical direction. Since the shaft 117 is restricted by the linear guide 122 from movement other than vertical movement, the float 117
It can be moved up and down in conjunction with.

At the upper end of the shaft 117, an arm 123 is provided.
Is fixed in the horizontal direction, and an optical fiber 701 at one end of the FBG 119 is fixed to the tip of the arm 123. Block 11 fixed to detection cell 114
8, an optical fiber 701 at the other end of the FBG 119 is fixed. Further, in order to restrain the vertical movement of the shaft 117, the lower limit stopper 120 and the upper limit stopper 12
1 is fixed to the detection cell 114.

The FBG 119 is fixed so that its water level is low and buoyancy does not act on the float 115 so as to maintain its natural length. In this state, the arm 123 is in contact with the lower limit stopper 120. At this time, the diaphragm 11
Reference numeral 6 denotes a state in which the float 115 is extended by its own weight. Further, in a state where the float 115 rises due to the buoyancy and the arm 123 contacts the upper limit stopper 121,
The diaphragm 116 is formed so as not to be deformed. This diaphragm 116 is a float 115
The shaft 117 is deformed by its own weight, but the amount of deformation is limited by the lower limit stopper 120.

Next, the operation of this embodiment will be described. When the water level is at the level of W1 as shown in FIG. 12A, no buoyancy acts on the float 115 and the FBG 119 keeps its natural length, so that no load is generated. At this time, the weight of the float 115 and the shaft 117 acts on the diaphragm 116, but the arm 123 is
It is in contact with 0 and is at the lower limit position.

When the water level changes to the position W2 as shown in FIG. 12B, buoyancy is generated in the float 115. Due to this buoyancy, when the float 115 moves upward, the shaft 117 and the arm 123 work together, and the FBG 119
Is stretched. Here, since the upward movement of the shaft 117 is limited by the contact between the arm 123 and the upper limit stopper 121, the load applied to the FBG 9 does not change beyond a certain value.

When the water level returns to W1, the force of the FBG 109 to return to its natural length and the weight of the shaft 117 and the float 115 are applied, and the arm 123 moves to the lower limit stopper 1
Stop at the position where it comes into contact with 20. As described above, the FBG 119 is elongated with the movement of the shaft 117 and the arm 123 due to the change in the water level, and the wavelength of the reflected light also changes from a short wavelength to a long wavelength. Is constantly detected, it is possible to detect that the water level or the water pressure has exceeded a set value.

Also in this embodiment, the float 115
The movement of the shaft 117 connected to the linear guide 12
2 restricts the vertical movement only, so that even if the flow of water acts on the float 115 in the horizontal direction, the FBG
119 is less affected. Further, when the bellows 106 is used as in the tenth embodiment, if dust or the like enters the gap between the bellows 106, the bellows 106 is less likely to be deformed and may not operate. In this regard,
The eleventh embodiment has a feature that the use of the diaphragm 116 instead of the bellows 106 eliminates a detection failure for dust or the like and improves reliability.

FIG. 13 shows a twelfth embodiment of the present invention. This embodiment also transmits buoyancy acting on the float due to a change in water level to the FBG, and detects a change in the reflection wavelength. In the present embodiment, the float 125 that moves up and down according to the water level includes the diaphragm 126 and the leaf spring 1.
27 and are connected. Diaphragm 126
Is fixed to the detection cell 124 side, and the leaf spring 127 is fixed to a pair of rods 135 extending from the detection cell 124.

Inside the detection cell 124, a shaft 128 for transmitting the vertical movement of the diaphragm 126 is mounted on the upper surface of the center of the diaphragm 126, and the shaft 128 extends in the vertical direction. In order to accurately transmit the displacement transmitted from the diaphragm 126, the lower end surface of the shaft 128 is desirably spherical. The shaft 128 is regulated by a linear guide 129 so that it can only move up and down. An arm 132 is fixed to the upper end of the shaft 128 in the horizontal direction.
The tip of the arm 132 is fixed to an optical fiber 701 on one end of the FBG 133, and the optical fiber 701 on the other end of the FBG 133 is fixed to a block 134 attached to the detection cell 124.

The lower limit stopper 130 is fixed below the leaf spring 127, and regulates the deformation of the leaf spring 127 at the center thereof to regulate the lower limit position of the vertical movement of the shaft 128 on the diaphragm 126. Upper limit stopper 131
Is installed inside the detection cell 124, and functions as a stopper by regulating the upper limit position of the arm 132 that moves up and down in conjunction with the shaft 128.

The diaphragm 126 and the leaf spring 127
In a state where no buoyancy is applied to the float 125, the float 125 receives a load in the direction of gravity due to its own weight and deforms in the direction of gravity, but does not deform beyond the position where the leaf spring 127 contacts the lower limit stopper 130. At this time, the shaft 128 placed on the diaphragm 126 is at the lower limit position, and the FBG 133 is set to maintain the natural length in that state.

Next, the operation of this embodiment will be described. As shown in FIG. 13 (a), when the water level is at the level of W1 and buoyancy does not act on the float 125, the weight of the float 125 and the shaft 128 acts on the diaphragm 126 and the leaf spring 127. 127 is held at a position where it contacts the lower limit stopper 130.

When the water level changes to the position W2, the float 125 generates buoyancy. When the float 125 moves upward due to the buoyancy, the diaphragm 126 and the leaf spring 127 also deform upward, and simultaneously push up the shaft 128. Then, the FBG 133 fixed to the arm 132 driven by the shaft 128 is extended. At this time, the upward movement of the shaft 128
The load applied to the FBG 133 does not change by a certain value or more because it is regulated by the contact of the 32 with the upper limit stopper 131.

When the water level returns to W1, the force of the FBG 133 to return to its natural length and the weight of the shaft 128 and the float 125 stop at the position where the leaf spring 127 contacts the lower limit stopper 130. As described above, the FBG 119 is elongated with the change of the water level, and the reflected light wavelength also changes from the short wavelength to the long wavelength. Therefore, if the reflected light wavelength is always detected by the wavelength conversion unit,
It can be detected that the water level or the water pressure has exceeded the set value.

The feature of this embodiment resides in that the float 125 is connected between the leaf spring 127 and the diaphragm 126. That is, in the embodiment shown in FIG. 12, the diaphragm and the float must be connected to the shaft so that the water level can be accurately detected even when there is a flow of water. However, when the thickness of the diaphragm is reduced, it is difficult to assemble the whole while fixing the diaphragm to the shaft and the float, and there is a problem that the diaphragm itself is also difficult to fix uniformly to the detection cell.

On the other hand, in this embodiment, since the float 125 is connected to the diaphragm 126 and the leaf spring 127 with the float 125 interposed therebetween, the float 125 is less affected by the flow of water in the horizontal direction. As a result, there is no need to connect the diaphragm 126 and the shaft 128, and it is sufficient to simply mount the shaft 128 on the diaphragm 126, so that the structure can be simplified.

FIG. 14 shows a thirteenth embodiment of the present invention. This embodiment also transmits buoyancy acting on the float due to a change in water level to the FBG, and detects a change in the reflection wavelength. In the present embodiment, a float 137 that moves up and down according to the water level is accommodated in the detection cell 136. A water inlet 500 having a diameter smaller than the diameter of the float 137 is formed on the bottom surface of the detection cell 136, so that the float 137 does not go out of the detection cell 136.

An air vent 501 is formed on the side surface of the detection cell 136 so that air is discharged when water is introduced from the water inlet 500. Diaphragm 1
Reference numeral 38 is fixed to the detection cell 136 side by a method of maintaining airtightness such as electron beam welding. Further, a pressure receiving portion 139 for transmitting a force due to the vertical movement according to the buoyancy of the float 137 to the diaphragm 138 is attached to the lower surface center of the diaphragm 138, and a block 139b is attached to the opposite upper surface center. I have. This block 13
9b, an optical fiber 701 at one end of the FBG 141 is provided.
Are fixed by means such as bonding, and the optical fiber 701 on the other end side of the FBG 141 is fixed to a block 139 a fixed to the detection cell 136.

Reference numeral 502 denotes an upper limit stopper for restricting deformation of the diaphragm 138.
It is fixed to. Diaphragm 138 and FBG14
1 is F when the float 137 is not floating due to buoyancy.
Block 1 with BG 141 extended beyond its natural length and diaphragm 138 extended beyond normal.
39b. When the float 137 is floated by buoyancy, the diaphragm 138 is pressed by the float 137 and further expanded, while the FBG 141 contracts and returns to its natural length.

Next, the operation of this embodiment will be described. When the water level is at the level of W1 and no buoyancy acts on the float 137, no buoyancy acts on the diaphragm 138. At this time, since the FBG 141 is fixed while being extended by the diaphragm 138 and the block 139b, a reflected waveform on the long wavelength side is detected.

When the water level changes to the position W2, buoyancy is generated in the float 137. The float 137 moved upward by this buoyancy comes into contact with the diaphragm 138, and pushes up the pressure receiving portion 139 upward. Then, since a load is applied by the amount of the buoyancy, the diaphragm 138 is further extended, and conversely, the FBG 141 is contracted, so that a reflected waveform on the short wavelength side is detected. Since the deformation of the diaphragm 138 is regulated by the contact of the block 139b with the upper limit stopper 502, the load applied to the FBG 141 does not change beyond a certain value.

When the water level returns to W1, the float 137
Diaphragm 138 and FBG
The state returns to the initial state in which the force relationship with 141 is balanced. The compression wavelength of the FBG 141 changes its reflection wavelength from a long wavelength to a short wavelength, so that it is possible to detect that the water pressure or the water level has exceeded a set value. A feature of this embodiment is that the float is not fixed to the diaphragm or the bellows as in the tenth to twelfth embodiments, so that the airtightness in the detection cell can be easily ensured.

FIG. 15 shows a fourteenth embodiment of the present invention. In this embodiment, a magnet is embedded in a float that moves up and down with a change in water level, and a magnetic body is fixed on the FBG side, thereby converting the up and down movement of the float into a magnetic field, that is, a change in magnetic attraction. By acting on the FBG, a change in the water level is detected as a change in the reflection wavelength of the FBG.

In this embodiment, a magnet 144 as a first magnetic material is embedded in a float 143 that moves up and down according to the water level. At this time, the float 143 is
The specific gravity and volume are secured so that the magnet 144 can operate as a float even if it is embedded. Detection cell 1
By making the diameter of the water inlet 510 of the detection cell 142 shorter than the diameter of the float 144 accommodated in the, the float 143 is prevented from coming out of the detection cell 142.

An air vent 511 is formed on the side of the detection cell 142 so that air is discharged when water is introduced from the water inlet 510. The partition 147 is
A non-magnetic material that does not deform even when subjected to buoyancy by the float 143 and does not take on magnetic force due to the influence of a magnetic field is used. This partition 14
Reference numeral 7 is fixed to the detection cell 142, and is fixed to the FBG 146 side with airtightness so that water does not enter. FBG
The optical fiber 701 on which the 146 is formed is
8a and the block 148b are fixed at one end to each other, and a magnetic body 145 as a second magnetic material is provided at the center portion thereof.
6 in series. The FBG 146 is fixed between the blocks 148a and 148 so that the float 143 is not lifted by the buoyancy so as not to sag.

Next, the operation of this embodiment will be described. In a state where the water level is at the level of W1 and buoyancy does not act on the float 143, since the magnet 144 and the magnetic body 145 are separated, the FBG 146 is not extended, and a reflected waveform on the short wavelength side is detected. When the water level changes to the position of W2,
The float 143 moves upward due to buoyancy. As a result, the distance between the magnet 144 and the magnetic body 145 is reduced. During this time, a magnetic attraction acts to attract the magnetic body 145 to the magnet 144 side. Therefore, FBG14
6 is extended, and the reflected waveform on the long wavelength side is detected. When the water level returns to W1, the buoyancy of the float 143 is lost, and the float 143 returns to its initial state due to its own weight exceeding the magnetic attraction.

In the above-described tenth to thirteenth embodiments, a threshold is provided for turning on / off the wavelength change that changes in an analog manner due to the movement of the float. However, in this embodiment, the snap is performed by using a magnet. The effect that an action like action can be obtained and the hysteresis can be reduced can be obtained.

FIG. 16 shows a fifteenth embodiment, which is a modification of the fourteenth embodiment. That is, FBG15
The optical fiber 701 provided with the optical fiber 701 is folded and arranged in the vertical direction, the magnetic body 152 as a second magnetic material is fixed to the folded portion, and the base end side of the optical fiber 701 is fixed to the block 155. It is. In addition, 1
49 is a detection cell, 150 is a float, 151 is a magnet as a first magnetic material, 154 is a partition, 520 is a water inlet, and 521 is an air vent.

According to this embodiment, the magnetic body 152 moves as shown by the broken line due to the rise of the magnet 151 accompanying the rise of the water level, and the FBG 153 extends. In the fourteenth embodiment of FIG. 15, the movement amount of the magnetic body 145 is
Since the G146 does not elongate, the desired change in the wavelength of the FBG 146 may not be obtained unless the magnetic body 145 is largely displaced. That is, since it is necessary to secure a long moving distance of the magnetic body 145, there is a possibility that the entire apparatus becomes large. On the other hand, in the embodiment of FIG. 16, the moving direction of the magnetic body 152 and the direction in which the FBG 153 extends are the same,
Since the displacement of the magnetic body 152 acts on the FBG 153 as it is, it is not necessary to secure a long moving distance of the magnetic body 152, and the apparatus can be downsized.

FIG. 17 shows a sixteenth embodiment of the present invention. In this embodiment, similarly to the fourteenth and fifteenth embodiments, a magnet is embedded in a float that moves up and down with a change in water level, and a magnetic body is fixed on the FBG side.
FB by converting the vertical movement of the float into a change in magnetic attraction
It acts on G.

In this embodiment, a magnet 166 as a first magnetic material is fixed to the substantially cylindrical float 165 which moves up and down according to the water level by bonding, or the magnet 166 is built in by integral molding or the like. . Float 1
65 denotes an upper limit stopper 17 fixed to the detection cell 164.
It is inserted so as to move up and down between 0 and the lower limit stopper 169. The FBG 168 is formed on an optical fiber 701 that is folded back so as to be parallel to the movable direction of the float 165 in the detection cell 164, and a magnetic body 167 is fixed above the FBG 168 by bonding or the like. The optical fiber 701 at one end of the magnetic body 167 as the second magnetic material and the optical fiber 701 at the other end of the FBG 168 are fixed to blocks 171a and 171b, respectively. Here, the FBG 168 and the magnetic body 167
Are positioned on a straight line in a state where no buoyancy acts on the float 165.

Next, the operation of this embodiment will be described. As shown in FIG. 17A, when the water level is at the level of W1 and no buoyancy acts on the float 165, the magnet 166
And the magnetic body 167 are separated from each other, and the influence of the magnetic attraction is small and the magnetic body 167 is not attracted.
68 is not extended, and the reflected waveform on the short wavelength side is detected.

When the water level changes and reaches the position W2 in FIG. 17B, the float 165 generates buoyancy and moves upward. As a result, the distance between the magnet 166 and the magnetic body 167 is shortened, and the magnetic attraction between them is increased, so that the magnetic body 167 is attracted to the magnet 166 side. Then
Since the FBG 168 is extended, a reflected waveform on the long wavelength side is detected from the FBG 168.

When the water level returns to W1, the buoyancy of the float 165 disappears, and the float 165 returns to its initial state by its own weight exceeding the magnetic attractive force. The features of this embodiment are as follows.
4, a snap action operation similar to that of the fifteenth embodiment, and furthermore, since the float 165 has an annular shape and the detection cell 164 is inserted therein, the operation is possible even if the fluid for measuring the water level has a flow. The effect that there is is obtained.

FIG. 18 shows a seventeenth embodiment of the present invention. In this embodiment, a float that moves up and down in accordance with a change in water level is fixed to one side of the bellows, a magnet is embedded in the float, and a magnetic material is fixed to the FBG side, so that the up and down movement of the float is magnetically attracted. And changes it to act on the FBG.

In this embodiment, the float 157 which moves up and down according to the water level is fixed to one side of the bellows 159 by adhesion or welding while ensuring airtightness. Bellows 1
The other side of 59 is fixed to the partition 160 or the detection cell 156. As the material of the bellows 159, a non-magnetic material that does not take a magnetic force due to the influence of a magnetic field is used. Further, a magnet 158 as a first magnetic material is embedded in the float 157. At this time, the specific gravity and volume of the float 157 are ensured so that the float 157 can sufficiently operate as a float even when the magnet is embedded.

[0093] When the float 157 is immersed in water, air is discharged from the detection cell 156 so that the air vent 530 is provided.
Are formed on the side surface of the detection cell 156. Partition wall 160
Is formed of a non-magnetic material that does not deform even when subjected to buoyancy by the float 157 and does not take on magnetic force due to the influence of a magnetic field. Further, the partition wall 160 is fixed to the detection cell 156 with airtightness so that water does not enter the FBG 162 side.

The optical fiber 70 on which the FBG 162 is formed
1 has one end fixed to each of the blocks 163a and 163b, and a magnetic body 161 as a second magnetic material fixed to the center thereof. The optical fiber 701 is attached so that the float 157 does not slack due to the buoyancy.

Next, the operation of this embodiment will be described. In a state where the water level is at the level of W1 and no buoyancy acts on the float 157, the magnet 158 and the magnetic body 161 are separated from each other.
Since 61 is not attracted, the FBG 162 is not extended, and a reflected waveform on the short wavelength side is output.

When the water level changes to the position W2, the float 157 generates buoyancy and moves upward. As a result, the distance between the magnet 158 and the magnetic body 161 becomes shorter,
During this time, the magnetic attraction increases, and the magnetic body 161 is attracted to the magnet 158 side. Then, since the FBG 162 is extended, a reflected waveform on the long wavelength side is detected from the FBG 162. When the water level returns to W1, the buoyancy of the float 157 is lost, and the float 157 returns to the initial state due to its own weight exceeding the magnetic attraction.

In the mechanism for performing the snap action operation as in the above-described fourteenth to sixteenth embodiments, when dust or the like enters between the float having the built-in magnet and the partition, the magnetic attraction force between the magnet and the magnetic body is increased. It may be affected and stop working. Further, when the dust is a magnetic material, the dust may adhere to the float and may not perform its original function. On the other hand, in the present embodiment, since the space from the magnet 158 to the magnetic body 161 is covered with the bellows 159 to secure airtightness, the various inconveniences due to dust described above are solved, and the reliability is improved. Is obtained.

In the fourteenth to seventeenth embodiments,
It is also possible to use the first magnetic material as a magnetic material and the second magnetic material as a magnet (the float side as a magnetic body and the FBG side as a magnet).

FIG. 19 shows an eighteenth embodiment of the present invention. This embodiment embeds a weight and an FBG inside a float that moves up and down with a change in the water level, and transmits the load of the weight that moves according to the up and down movement of the float to the FBG. This is to detect.

In this embodiment, the float 173 that moves up and down according to the water level is fixed outside the detection cell 172. The float 173 and the detection cell 172 are connected at their ends to the bellows 178. Detection cell 17
The optical fiber 701 folded inside the FBG1 has FBG1
The optical fiber 701 at one end of the FBG 174 is fixed to the fixed end 17 fixed to the detection cell 172.
7, and a weight 175 is fixed to the optical fiber 701 on the other end side of the FBG 174 by bonding or the like. The weight 175 is housed inside the stopper 176, and the vertical and horizontal movements are restricted. Further, when the float 173 is not receiving buoyancy, F
The BG 174 is set to keep the natural length.

Next, the operation of this embodiment will be described with reference to FIG. In the state of FIG. 20A in which the water level is at the level of W1 in FIG. 19, since the vertical relationship between the weight 175 and the fixed end 177 is such that the fixed end 177 is below, the FBG 17
4, a load acts in the compression direction. In the state of FIG. 20B where the water level changes to the position of W2, the weight 17
Since 5 is lower than the fixed end 177, a load acts on the FBG 174 in the tensile direction. Then, FBG17
4 is extended by the load of the weight 175, so that the reflected waveform on the long wavelength side is detected. In this embodiment, since the magnet is not used unlike the fourteenth to seventeenth embodiments, the effect that the reliability with respect to the temperature is high can be obtained.

FIG. 21 shows a nineteenth embodiment of the present invention. This embodiment has a float that is fixed at one end by an arm and that rotates with a change in the water level, and transmits the rotation to the FBG via a stepped shaft to change the water level with the reflection wavelength of the FBG. The change is detected as a change.

In this embodiment, the stepped shaft 1
82 is accommodated in the detection cell 179 and the bearings 183, 18
4 and is hermetically sealed by an O-ring 540. One end of the stepped shaft 182 has an arm 1
The float 180 is connected to the float 180 through a stepped shaft 182.
This is converted into a rotating motion of A step 187 is formed substantially at the center of the stepped shaft in the axial direction, and a block 187a for fixing one end of the optical fiber 701 having the FBG 185 is attached to the upper end thereof. The other end of the optical fiber 701 is
9 is connected to a block 186 fixed to it.

The rotation range of the stepped shaft 182 is regulated by a pair of stoppers 541. The block 187a, the FBG 185, and the block 186 are arranged in a straight line with the float 180 not receiving buoyancy and the step portion 187 standing upright between the pair of stoppers 541. At this time, the FBG 185 keeps its natural length. .

Next, the operation of this embodiment will be described with reference to FIG. In the state of FIG. 22A where the water level is at the level of W1 in FIG. 21, the block 187a and the FBG 18
5. Since the block 186 is on a straight line and the FBG 185 maintains its natural length, a reflected waveform on the short wavelength side is detected. In the state of FIG. 22B where the water level changes to the position of W2, the stepped shaft 182 rotates and the block 18 moves.
7a also rotates, but since the block 186 fixed to the detection cell 179 is fixed, the distance between the block 187a and the block 186 increases. That is, FB
Since G185 is extended, a reflection waveform on the long wavelength side is detected from FBG185. According to this embodiment, the float 180 comprises the shaft 182 and the arm 1
Since it is supported by 81, even if there is a flow in the water, it is hardly affected by the flow and the effect of improving the reliability is obtained.

FIG. 23 shows a twentieth embodiment of the present invention. This embodiment detects the water level change as a change in the reflection wavelength of the FBG by transmitting the displacement of the float that rotates with the water level change to the FBG via a snap action mechanism using a spring. .

In this embodiment, the shaft 191 is
It is supported by a bearing 192, and is rotatably attached to the detection cell 188 while maintaining airtightness by an O-ring 550. A first arm 190 is provided at one end of the shaft 191 on the side in contact with the fluid whose water level is to be detected.
Is attached via a float 189.

Since the arm 190 and the shaft 191 are interlocked with each other, the float 18 which rotates with a change in the water level can be used.
9 is transmitted to the shaft 191 and the shaft 191
Also rotates. A second arm 193 is attached to the other end of the shaft 191 in the detection cell 188, and rotates around the shaft 191 as the float 189 rotates, similarly to the arm 190. Also, the second arm 19
Above and below 3, a pair of stoppers 552 for regulating the rotation range are arranged.

The third arm 193 is orthogonal to the second arm 193.
Arm 194 is attached.
4 is connected to a fourth arm 196. A part of the fourth arm 196 is a spring 195, one end of which is fixed to a fixed end 551 formed in the detection cell 188. Note that the spring 195 is extended beyond its natural length, and a force always acts in the compression direction. Fourth arm 1
The other end of 96 is directly below FBG 197 and float 18
The FBG 197 is configured to be pressed from below by an arm 196 that follows the FBG 9. Also, FBG1
Reference numeral 97 denotes an optical fiber 70 folded back in the detection cell 188.
1 and both ends of the FBG 197 are fixed by a pair of blocks 198a and 198b. These blocks 198a and 198b are fixed to the detection cell 188.

Next, the operation of this embodiment will be described with reference to FIG. FIG. 24 is a view of FIG. 23 viewed from a horizontal plane. In the state of FIG. 24A in which the water level is at the level of W1, the float 189 is lowered, and in this state, the force in the compression direction by the spring 195 is applied to the arm 19.
6, 194 acting on the shaft 191. FBG
197 is on the same straight line as the blocks 198a and 198b and is not in contact with the arm 196, so that a reflected waveform on the short wavelength side is detected.

FIG. 24 in which the water level changes to the position of W2
In the state of (b), the float 189 changes as the water level changes.
Rotates around the shaft 191. This allows
The arm 190, the shaft 191 and the arm 193 rotate simultaneously. At this time, the arm 1 orthogonal to the arm 193
The arm 94 also moves in parallel, and the arm 1 connected to the arm 194
96 also tries to move at the same time.

The arm 196 is about to rotate about the fixed end 551, but the spring 195 is further extended once due to the difference in the radius of rotation of the arms 193 and 196.
When the arm 196 exceeds the extension of the central axis of the shaft 191, the resilience of the spring 195 is reversed,
The direction of the force changes to a state in which the float 189 is about to be pulled in the counterclockwise direction about 1. When the arm 196 exceeds the extension of the central axis of the shaft 191, the tip of the arm 196 contacts the lower end of the FBG 197. Thereafter, the FBG 197 is extended while being lifted up by the rotating arm 196, so that the reflected waveform on the long wavelength side is detected. According to this embodiment, by using the snap action mechanism using the spring 195, it is possible to detect the vibration when there is no fluid to be detected and the flow of the detected fluid.

FIG. 25 shows a twenty-first embodiment of the present invention. In this embodiment, similarly to the twentieth embodiment, the displacement of the float that rotates with the water level is transmitted to the FBG by a snap action mechanism using a spring, and the water level change is detected as a change in the reflection wavelength of the FBG. It was done.

In this embodiment, the arm 401 is provided with a float 401 arranged on the side which comes into contact with the fluid whose water level is to be detected.
The arm 402 is attached to the detection cell 400 via a cover 404 and a spherical bearing 403 for providing airtightness. Arm 4
02 is swingably supported by a spherical bearing 403.

At the other end of the arm 402, a snap action mechanism is mounted in the detection cell 400. This snap action mechanism is provided by the arm 402
Arm 405, a plate 406 in contact with the tip of the arm 405, a spring 407 for applying elastic force to the plate 406,
2 and a pair of stoppers 560 arranged above and below the other end of the second stopper.

The function of the snap action mechanism is as follows. As shown in FIG. 25B, the water level is W1
In the case of, the plate 406 urged by the spring 407 presses the tip of the arm 405 obliquely from below, so that a force for rotating the float 401 in the counterclockwise direction acts on the float 401, and the tip of the arm 402 is By contacting the upper stopper 560, the float 401 is stabilized at the position indicated by the solid line in FIG. When the water level is W2, the float 401 rises, and the plate 406 presses the tip of the arm 405 obliquely from above. Is in contact with the lower stopper 560, so that the float 401 is stabilized at the position indicated by the broken line in FIG.

In FIG. 25, blocks 409a and 409b are fixed in the detection cell 400, and the FBG 408 is connected to an optical fiber 701 disposed therebetween.
Are formed. Above the FBG 408, the other end of the arm 402 is arranged.
02 can contact the FBG 408 from above.

Next, the operation of this embodiment will be described. In the state where the water level is at the level of W1, the float 401 is lowered, and in this state, the force for rotating the float 401 in the counterclockwise direction about the spherical bearing 403 acts as described above. However, since the other end of the arm 402 is in contact with the upper stopper 560, the rotation of the float 401 is restricted. At this time, F
The BG 408 is on the same straight line as the blocks 409a and 409b and does not touch the arm 402, so that a reflected waveform on the short wavelength side is detected.

When the water level changes to the position W2, the float 401 rotates around the spherical bearing 403 with the change in the water level, and the arm 402 follows the rotation. Arm 40
The spring 407 receives a load in the compression direction with the rotation of 2, but when the arm 402 exceeds the center of the spherical bearing 403,
The resilience of the spring 407 against the float 401 is reversed, and the direction of the load changes clockwise. At that time, the arm 40
Since the FBG 408 is disposed below the other end of the second 2, the arm 402 comes into contact with the FBG 408 to extend the FBG 408, and the FBG 408 outputs a reflected waveform on the long wavelength side. The rotation of the arm 402 following the float 401 is regulated by the other end of the arm 402 abutting on the lower stopper 560. Also in this embodiment, by using the snap action mechanism using the spring 407, it is possible to detect the vibration when there is no fluid to be detected and the flow of the detected fluid.

FIG. 26 is a configuration diagram of a multipoint detection system using a plurality of optical water level detectors of each of the above embodiments.
In the figure, 200 is a white light source, 201, 202, 20
3 is an optical fiber, 204 is an optical coupler, and 300 is a wavelength detector. S1, S2,..., And Sn are optical water level detectors of the respective embodiments, and are installed in a sewage tank or a sewage flow path for detecting a water level or a water pressure according to the water level. Since the reflected light wavelengths of the FBGs can be appropriately set so as not to overlap with each other, even in the case of a multi-point detection system as shown in FIG. 26, light of a specific wavelength different from the internal FBG is reflected for each installation location of the detector. With such a configuration, it is possible to reliably detect whether the water level and the water pressure at each point have exceeded the set values,
It can be applied to flow control of sewage and the like.

In each of the embodiments described above, the wavelength of the reflected light from the FBG is detected. However, since the FBG also has a property of transmitting light of a specific wavelength, the transmitted light is detected and the water level and water pressure are detected. Detectors to be detected are also included in the equivalent scope of the present invention.

[0122]

As described above, according to the present invention, the water level and the water pressure corresponding to the water level can be easily detected by a relatively simple structure having a small number of mechanically movable parts. Since there is no need to secure the space, there is an excellent effect that the installation place is not selected.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a first embodiment of the present invention.

FIG. 2 is a configuration diagram showing a second embodiment of the present invention.

FIG. 3 is an explanatory diagram of a spectrum of a reflected light wavelength of the FBG.

FIG. 4 is a configuration diagram showing a third embodiment of the present invention.

FIG. 5 is a configuration diagram showing a fourth embodiment of the present invention.

FIG. 6 is a configuration diagram showing a fifth embodiment of the present invention.

FIG. 7 is a configuration diagram showing a sixth embodiment of the present invention.

FIG. 8 is a configuration diagram showing a seventh embodiment of the present invention.

FIG. 9 is a configuration diagram showing an eighth embodiment of the present invention.

FIG. 10 is a configuration diagram showing a ninth embodiment of the present invention.

FIG. 11 is a configuration diagram showing a tenth embodiment of the present invention.

FIG. 12 is a configuration diagram showing an eleventh embodiment of the present invention.

FIG. 13 is a configuration diagram showing a twelfth embodiment of the present invention.

FIG. 14 is a configuration diagram showing a thirteenth embodiment of the present invention.

FIG. 15 is a configuration diagram showing a fourteenth embodiment of the present invention.

FIG. 16 is a configuration diagram showing a fifteenth embodiment of the present invention.

FIG. 17 is a configuration diagram showing a sixteenth embodiment of the present invention.

FIG. 18 is a configuration diagram showing a seventeenth embodiment of the present invention.

FIG. 19 is a configuration diagram showing an eighteenth embodiment of the present invention.

FIG. 20 is an operation explanatory diagram of the eighteenth embodiment.

FIG. 21 is a configuration diagram showing a nineteenth embodiment of the present invention.

FIG. 22 is an operation explanatory diagram of the nineteenth embodiment.

FIG. 23 is a configuration diagram showing a twentieth embodiment of the present invention.

FIG. 24 is an operation explanatory diagram of the twentieth embodiment.

FIG. 25 is a configuration diagram showing a twenty-first embodiment of the present invention.

FIG. 26 is a configuration diagram of a multipoint detection system showing an application example of the present invention.

[Explanation of symbols]

10, 20, 30, 40, 50, 60, 70, 90 Detection cell 11 Input optical fiber 12 Output optical fiber 13 Vertical movement unit 14 Holding unit 15, 16 Intermediate optical fiber 17 Connecting unit 18a, 18b, 18c, 18d, 44a , 44b, 5
4a, 54b Spring 19, 32, 42, 52, 62, 72, 82, 92, 1
02 FBG 20, 48, 57 float 31, 41, 51, 61, 71, 81, 91, 101,
201 to 203 Optical fiber 33, 34, 74, 75 Magnet 43 Guide disk 45, 58 Support point 46a, 46b, 56a, 56b Telescopic rod 47 Block 49, 53 Arm 63, 73 Diaphragm 82a Cutting part 83, 93 Pressure receiving part 92a Clearance 94 Matching oil 103 Pressure receiver 200 White light source 204 Optical coupler 300 Wavelength detector 491,492,541,591,592 Stopper 104,114,124,136,142,149,1
56, 164, 172, 179, 188, 400 Detection cells 105, 115, 125, 137, 143, 150, 1
57,165,173,180,189,401 Float 106,159,178 Bellows 107,122,129 Linear guide 108,117,128,191 Shaft 109,119,133,141,146,153,1
62, 168, 174, 185, 197, 408 F
BG 110, 120, 130, 169 Lower limit stopper 111, 121, 131, 170 Upper limit stopper 112, 118, 134, 139a, 139b, 148
a, 148b, 155, 163a, 163b, 171
a, 171b, 186, 187a, 198a, 198
b, 409a, 409b Blocks 113, 123, 132, 181, 190, 194, 1
96, 402, 405 Arm 116, 126, 138 Diaphragm 127 Leaf spring 135 Rod 139 Pressure receiving part 144, 151, 158, 166 Magnet 145, 152, 161, 167 Magnetic body 147, 154, 160 Partition 175 Weight 176, 552, 560 Stopper 177,551 Fixed end 182 Stepped shaft 183,184,192 Bearing 187 Step 187a Block 403 Spherical bearing 404 Cover 406 Plate 407 Spring 500,510,520 Water inlet 501,511,521,530 Air vent 502,170 Upper limit stopper 540, 550 O-ring 701 Optical fiber S1-Sn detector

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Masakazu Ikoma 1-1, Tanabe-Nitta, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture Inside Fuji Electric Co., Ltd. (72) Inventor Shinji Takamizawa 1 Tanabe-Nitta, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture No. 1 Fuji Electric Co., Ltd. (72) Inventor Akihiro Ishiishi 1-1, Tanabe Nitta, Kawasaki-ku, Kawasaki City, Kanagawa Prefecture Inside Fuji Electric Co., Ltd. (72) Inventor Yasuhiro Yokoyama 1, Tanabe Nitta, Kawasaki-ku, Kawasaki City, Kanagawa Prefecture No. 1 Inside Fuji Electric Co., Ltd.

Claims (22)

[Claims] A float that floats on water whose water level is to be detected, a vertically moving unit that can move up and down in a detection cell following the float, an input optical fiber that causes detection light to enter the inside of the detection cell, An output optical fiber into which light emitted from the input optical fiber via the vertical movement unit from the input optical fiber inside the detection cell, and the vertical movement unit has a water level equal to or lower than a set value and the vertical movement unit has a bottom dead center. A first intermediate optical fiber positioned in line with the input optical fiber and the output optical fiber when the vertical movement unit is at the top dead center when the water level is equal to or higher than a set value; A second intermediate optical fiber that is aligned with the fiber and that has an optical fiber Bragg grating. 2. A float that floats on the water whose water level is to be detected, and has an optical fiber Bragg diffraction grating in a part penetrating the detection cell, and can move up and down in the detection cell following the float. An optical fiber on which the detection light is incident; a first magnet attached to the optical fiber; and a second magnet fixed inside the detection cell and capable of being attracted to the first magnet. The internal optical fiber is at a position determined by the attraction of the first and second magnets when the water level is equal to or lower than the set value, and when the water level is equal to or higher than the set value, the first magnet released from the attraction with the second magnet. An optical water level detector characterized by being located at a position determined by the top dead center. 3. A float floating on the water whose water level is to be detected, an arm rotatably supporting the float, a fulcrum of the arm provided in the detection cell, and a circumstance surrounding the fulcrum. An optical fiber having one end fixed to the arm and the other end fixed inside the detection cell and having an optical fiber Bragg diffraction grating, on which detection light is incident; and An optical water level detector characterized in that one end fixed to an arm is movable in accordance with a vertical movement of a float accompanying a change. 4. A float floating on the water whose water level is to be detected, an arm rotatably supporting the float, a fulcrum of the arm provided in a detection cell, and the float via the fulcrum. An optical fiber, one end of which is fixed to the opposite end of the arm, and on which detection light is incident. The optical fiber has one end fixed to the arm which moves in accordance with the vertical movement of the float accompanying a change in water level. An optical water level detector characterized in that it is possible. 5. An airtight detection cell having a diaphragm responsive to a water pressure corresponding to a water level, an optical fiber Bragg diffraction penetrating through the inside of the thickness of the diaphragm, being integrated with the diaphragm, and having detection light incident thereon. An optical water level detector, comprising: an optical fiber having a grating; 6. An airtight detection cell having a diaphragm responsive to a water pressure according to a water level, an optical fiber penetrating the inside of the detection cell, receiving detection light, and having an optical fiber Bragg diffraction grating; An optical water level detector, comprising: a pair of magnets that are attracted and released so as to move an optical fiber in the detection cell according to a change in water pressure. 7. A pressure receiving portion which is deformed in response to a water pressure according to a water level, and an optical fiber which is integrally fixed to the pressure receiving portion, has a plurality of cut portions on an optical axis, and on which detection light enters. An optical water level detector, comprising: deforming an optical fiber including the cut portion by deforming the pressure receiving portion, and forming an optical fiber Bragg diffraction grating by interposing air in the cut portion. 8. An optical fiber Bragg diffraction grating is formed by a pressure receiving portion that moves in response to a water pressure corresponding to a water level and is fixed in a detection cell and has a plurality of gaps on an optical axis, and detection light is incident. An optical fiber, and a liquid filled so as to fill the gap as the pressure receiving portion moves and having the same refractive index as the optical fiber. 9. A hollow pressure receiving member which is deformed in response to a water pressure corresponding to a water level, and a light which is tightly wound around the outer peripheral surface of the pressure receiving member, has an optical fiber Bragg diffraction grating, and receives detection light. An optical water level detector, comprising: a fiber; 10. An optical fiber on which an optical fiber Bragg diffraction grating is formed, and operates when a water level or a water pressure corresponding to the water level becomes a predetermined value or more, and applies a strain to the Bragg diffraction grating, and when the water pressure becomes a predetermined value or less, the distortion is generated. A light level detector, comprising: 11. A float that floats on water whose water level is to be detected, a bellows that expands and contracts by following the float, a shaft that can move up and down in the detection cell by following the float, and a linear guide that guides the shaft. A guide, an arm fixed to the shaft and driven by the shaft, a stopper for restricting the vertical movement of the arm, and one end fixed to the arm and the other end fixed to the detection cell and internally. An optical water level detector, comprising: an optical fiber having an optical fiber Bragg diffraction grating formed thereon. 12. A float that floats on the water whose water level is to be detected, a diaphragm that expands and contracts by following the float, a shaft that can move up and down in the detection cell by following the diaphragm, and a linear guide that guides the shaft. A guide, an arm fixed to the shaft and driven by the shaft, a stopper for restricting the vertical movement of the arm, and one end fixed to the arm and the other end fixed to the detection cell and internally. An optical water level detector, comprising: an optical fiber having an optical fiber Bragg diffraction grating formed thereon. 13. A float that floats on water whose water level is to be detected, a diaphragm that expands and contracts following the float, and that is disposed between the float and a detection cell; and a float that is disposed below the float. A shaft mounted on the diaphragm so as to be able to move up and down in the detection cell following the diaphragm, a linear guide for guiding the shaft, and a shaft fixed to the shaft. An arm following the arm, a stopper for restricting upward movement of the arm, and one end fixed to the arm and the other end fixed to the detection cell, and an optical fiber Bragg diffraction grating formed inside. An optical water level detector comprising: an optical fiber; 14. A float that floats on the water whose water level is to be detected, a detection cell in which the float is housed, a water inlet for introducing water into the float, and a detection cell when the water is introduced. An air vent for bleeding air, a pressure receiving portion that comes into contact with the float that has moved upward in the detection cell by buoyancy, a diaphragm to which the pressure receiving portion is fixed, a block that follows the diaphragm, An optical fiber having one end fixed and the other end fixed to the detection cell and having an optical fiber Bragg diffraction grating formed therein. 15. A float floating on water whose water level is to be detected, a first magnetic material built in the float, a detection cell containing the float, and water for introducing water into the detection cell. An inlet, an air vent for bleeding air from the detection cell when water is introduced, and a partition made of a non-magnetic material that is arranged above the float and that is not deformed by pressure. An optical fiber fixed to a block on the partition wall and arranged in parallel with the partition wall, and having a second magnetic material and an optical fiber Bragg diffraction grating provided in series between both ends thereof; Causes a magnetic force to act between the first magnetic material and the second magnetic material to move the second magnetic material by a snap action operation and apply a load to the optical fiber Bragg diffraction grating. Optical water level detector, characterized in that there was Unishi. 16. A float floating in water whose water level is to be detected, a first magnetic material built in the float, a detection cell in which the float is stored, and water for introducing water into the detection cell. An inlet, an air vent for bleeding air in the detection cell when water is introduced, and a partition made of a non-magnetic material that is arranged above the float and that is not deformed by pressure, Is fixed above the partition wall and the other end is the second
An optical fiber connected to the magnetic material and having an optical fiber Bragg diffraction grating formed between both ends thereof, wherein the float moves up and down between the first magnetic material and the second magnetic material. An optical water level detector characterized in that a magnetic force is applied to move a second magnetic material by a snap action operation to apply a load to an optical fiber Bragg diffraction grating. 17. A substantially cylindrical float floating on water whose water level is to be detected, a first magnetic material built in the float, a detection cell arranged at the center of the float, and an inside of the detection cell. An optical fiber having both ends fixed, and a second magnetic material and an optical fiber Bragg diffraction grating provided in series between both ends, wherein the first magnetic material and the second magnetic material are moved by the vertical movement of the float. An optical water level detector characterized in that a magnetic force acts between the magnetic material and the second magnetic material to move the second magnetic material by a snap action operation to apply a load to the optical fiber Bragg diffraction grating. 18. A float that floats on water whose water level is to be detected, a first magnetic material built in the float, a detection cell in which the float is stored, and when water is introduced into the detection cell. An air vent for bleeding the air in the detection cell, and a partition made of a non-magnetic material that is arranged above the float and that is not deformed by pressure, and a stretchable bellows that connects the float and the partition, An optical fiber having both ends fixed to a block on the partition wall and arranged in parallel with the partition wall, and a second magnetic material and an optical fiber Bragg diffraction grating provided in series between both end portions; A magnetic force acts between the first magnetic material and the second magnetic material by the up and down movement of the float to move the second magnetic material by a snap action operation. Optical water level detector, characterized in that as a load is applied to the grayed diffraction grating. 19. A float floating on water whose water level is to be detected, a detection cell built in the float, a bellows having one end connected to the float and the other end fixed, and one end in the detection cell. Is fixed to the fixed end, an optical fiber having a weight attached to the other end thereof and an optical fiber Bragg diffraction grating formed between both ends thereof, and the vertical movement of the float and the fixed end and the weight An optical water level detector characterized by changing a load applied to an optical fiber Bragg diffraction grating by reversing a vertical positional relationship. 20. A float floating on the water whose water level is to be detected, a stepped shaft connected to the float via an arm, and rotated in accordance with the vertical movement of the float, and the stepped shaft in the detection cell. An optical fiber having one end fixed to the step part, the other end fixed to the detection cell, and an optical fiber Bragg diffraction grating formed between both ends, and the vertical movement of the float An optical water level detector characterized by changing a load applied to an optical fiber Bragg diffraction grating by rotating a part. 21. A float which floats on water whose water level is to be detected, a shaft which rotates in accordance with the vertical movement of the float, and a first snap action by a spring in accordance with the rotation of the shaft in the detection cell. An arm holding the position and the second position, and an optical fiber disposed close to the arm, having both ends fixed to the detection cell, and having an optical fiber Bragg grating formed between both ends. An optical water level detector, comprising: when the arm is in the first position or the second position, the arm abuts on the optical fiber Bragg diffraction grating to apply a load. 22. A float floating on the water whose water level is to be detected, connected to the float via a spherical bearing, and rotated in accordance with the up and down movement of the float, and by a snap action operation by a spring in the detection cell. An arm that holds the first position and the second position, a light that is arranged close to the arm, has both ends fixed to the detection cell, and has an optical fiber Bragg grating formed between both ends. And a fiber, wherein the arm abuts the optical fiber Bragg grating to apply a load when the arm is in the first position or the second position.