JPH06331489A - Leakage detector - Google Patents

Abstract

PURPOSE:To reduce the generation of erroneous signal in a leakage detector which is constituted by using an optical fiber and a swelling material. CONSTITUTION:A swelling material storage chamber 110 is constituted so that it prevents a swelling material 109 before swelling from moving and constrains the swelling material 109 so that the swelling material 109 swells toward an inner space 108. Also, a leakage substance introduction part is provided at the wall part of a housing 111 opposing an inner space with the swelling material 109 in-between. A light reflection part 113a and a light non-reflection part 113b are provided at a screening member 113 mounted on the swelling material 109. Before the swelling material 109 swells, the light reflection part 113a is positioned within a light path and reflects incidence light toward the end face of the core of an optical fiber 2. When the swelling material 109 swells, the light non-reflection part 113b is positioned within the light path and does not reflect the incidence light toward the end face of the core. The inner space 108 in airtight state and a pressure control chamber 115 are made to communicate with each other through a communication path 116.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a leak detector for detecting a leak substance which has become liquid or vapor by using a swelling material which swells when absorbing a specific substance and an optical fiber.

[0002]

2. Description of the Related Art Chemical equipment for manufacturing petroleum products, petrochemical products, chemical products, etc., iron-making equipment, boilers for burning various fuels including nuclear fuel, power generation equipment, semiconductor manufacturing equipment, etc. 2. Description of the Related Art There are known leak detectors that detect various leaked substances such as various liquids leaked from oil such as oil, organic solvents, harmful substances, aqueous solutions (including radioactive aqueous solutions, acids, alkalis and pure water) and vapors thereof. As a place where the leak detector is used, there is a high possibility that a leak will occur from the equipment or the machines that make up the equipment, such as the gland and mechanical seal of rotating machinery, the gland of valves, the joints and welds of pipes, equipment. There are welds and manholes. Further, the places where the oil leak should be detected by the leak detector are the pits of tanks and yards, the pits of pumps and yards.

Hitherto, the detection of leakage of various leaked substances from various facilities has been carried out by a human being who travels around the facility machine and discovers it with his five senses to prevent accidents and disasters and manage the facility. In addition, recently, in order to save the labor, a pair of electrodes are placed with a substance whose electrical resistance changes in contact with these leaking substances, and a current is passed between the electrodes to cause electrical resistance. Leakage detectors that measure changes and detect leaks have been put into practical use. However, such a leak detector is large and expensive, and has a problem that an explosion-proof structure is required in a place where flammable materials are handled, so that its spread is hindered.

Therefore, various leak detectors for detecting leaks by using light instead of electricity have been proposed. For example, JP-A-56-110036 discloses a leak detector in which the ends of two optical fibers whose optical axes are aligned with each other are supported by a water-swelling material and a core of one or two optical fibers. A leak detector is disclosed in which an end portion is arranged toward a reflecting plate supported by a water-swelling material. These leak detectors detect changes in coupling efficiency and changes in the amount of reflected light to detect water immersion in optical fiber cables and the like. Further, Japanese Patent Laid-Open No. 2-147835 also discloses a leak detector that utilizes the swelling of a water-swelling material to cause an optical axis shift between two optical fibers to detect a leak.

[0005]

However, in the conventionally proposed leakage detector using the optical fiber, the influence of the vibration applied from the outside, the difference in the swelling mode of the swelling material due to the difference in the introduction mode of the leakage substance, No measures have been taken against the effects of changes in ambient temperature and the effects of substances not absorbed by the swelling material (particularly liquids). Therefore, the following problems have occurred.

(1) The vibration applied from the outside causes the optical fiber and the swelling material to vibrate, causing malfunction.

(2) When the introduction mode of the leaked substance is inappropriate, the swelling material locally expands, or the swelling direction is not fixed, and a malfunction occurs.

(3) Malfunction occurs due to expansion of the internal gas due to temperature rise.

(4) When the leaked substance is mixed in the solution, the solution enters the detection space in which the end of the optical fiber is housed and adheres to the end face of the optical fiber or the reflecting surface. Malfunction occurs. If the leaked substance is contained in the vapor, the vapor enters the detection space and an erroneous signal is generated.

An object of the present invention is to provide a leak detector which is constructed by using an optical fiber and a swelling material, in which the occurrence of false signals is small.

Another object of the present invention is to provide a leak detector for various oils, organic solvents, harmful substances, aqueous solutions and vapors thereof which is small in size, inexpensive and does not require an explosion-proof structure.

[0012]

A leak detector to which the present invention is directed emits light from an end face of a core to an internal space of the housing, the end of which is held by a housing and a holding portion provided inside the housing. The optical fiber, the leaking substance introducing part provided on the wall of the housing, and the swelling material accommodating chamber provided in the housing, are swollen by absorbing the leaking substance to be detected entered from the leaking substance introducing part. Swelling material,
A shielding member that moves in the internal space by utilizing the swelling of the swelling material and positions the light reflecting portion or the light non-reflecting portion in the optical path of the light emitted from the core when the swelling material swells.

As the optical fiber, a multimode optical fiber or a bundle optical fiber can be mainly used. The structure of the holding portion of the optical fiber is arbitrary, but a rigid support base made of engineering plastic such as epoxy resin or metal such as stainless steel and aluminum by a method such as molding or mechanical molding is provided,
Align the end face of the optical fiber with the side face of this rigid support,
It may be fixed so as to form a smooth surface. Alternatively, the exposed cladding and core except for the coating on one end of the optical fiber may be inserted into a tubular ferrule and fixed, and this may be bonded and fixed to a rigid support. The end portion of the optical fiber may be held by the holding portion with the coating. If necessary, a rod lens may be attached to the end face of the optical fiber to increase the diameter of the optical fiber beam, and the stroke of the shielding member may be increased in proportion thereto.

As a swelling material that swells in contact with various leaked substances, leaks to be detected include gasoline, naphtha, kerosene, heavy oil, crude oil, electrical insulating oil, machine oil, lubricating oil, soybean oil, cottonseed oil, olive oil, benzene. For various hydrophobic organic liquids such as toluene, xylene, trichloroethylene, and PCB, and low boiling point organic vapors, materials such as highly oil-absorbent resins, natural rubber, synthetic natural rubber, styrene rubber, and butadiene rubber can be used. For leaks to be detected, water (including radioactive substance-containing water), pure water, saline, hydrochloric acid, sulfuric acid, nitric acid, aqueous solutions such as aqueous ammonia and sodium hydroxide, and water vapor are superabsorbent resins, materials such as cellulose. Can be used. Furthermore, by using a swelling material formed by kneading powdery particles of a super absorbent polymer with rubber, any of the above leaked substances can be detected at the same time.

The shielding member may be directly fixed to the swelling material, or may be separately provided with a supporting mechanism and movably supported by the supporting mechanism. The light reflecting portion of the shielding member can be formed using a material having a light reflecting property such as aluminum. For example, the surface of a metal such as stainless steel or copper or an epoxy resin or a polymer such as rubber may be wet- or dry-plated with light-reflective aluminum or the like. Further, in the light non-reflecting portion, light may be absorbed or light may be transmitted. When the light non-reflecting portion is configured to absorb light, for example, a light absorbing material such as rubber or resin kneaded with carbon fine powder or a light absorbing surface-treated material is applied to the surface of the light shielding material. Just place it. As a result, when the swelling material swells and the light reflecting portion of the light shielding material deviates outside the radiation angle of the end face of the optical fiber, the incident light is not reflected.

It should be noted that the light beam such as the LED or LD connected to the end of the optical fiber on the incident light side of the optical fiber is adjacent to the beam.
It is possible to detect various leaked substances by inserting a splitter and detecting the presence / absence of reflected light from the light reflecting portion by a signal processor having various photodiodes as light receiving elements.

Targeting such a leak detector, each invention of the present application uses the following configuration. According to the first aspect of the invention, the swelling material storage chamber has a structure that prevents the swelling material from moving before swelling and restrains the swelling material so that the swelling material swells toward the internal space. Further, the leaking substance introducing portion is provided on the wall portion of the housing facing the internal space with the swelling material interposed therebetween.

In the second aspect of the invention, the shielding member is provided with the light reflecting portion and the light non-reflecting portion. Before the swelling material swells, the light reflecting portion is located in the optical path and reflects the incident light toward the end face of the core. When the swelling material is swelling, the light non-reflecting portion is located in the optical path and the incident light is reflected in the core. The light reflecting portion and the light non-reflecting portion are arranged on the shielding member in such a positional relationship that they are not reflected toward the end face of the.

According to the third aspect of the invention, the light reflecting surface of the light reflecting portion is set to be not less than 2 times and not more than 20 times the area of the end surface of the core with the optical axis of the light incident from the core as the center. Then, the light non-reflecting portion is arranged outside the light reflecting surface.

Further, in the invention of claim 4, after the shielding member is fixed to the swelling material, the portion where the shielding member is fixed is centered at the end of the inner space of the housing on the side of the swelling material accommodating chamber. A guide portion for guiding the swelling material is provided so that the swelling material swells. The shape of this guide portion is arbitrary. For example, if the guide portion is tapered so as to be inclined toward the center of the internal space, the swelling material can be swollen around the portion where the shielding member is most reliably fixed. You can

According to the invention of claim 5, the swelling material is accommodated in the swelling material accommodating chamber in a state of being pressed by the wall portion of the housing provided with the leakage substance introducing portion. The leaking substance introducing portion is composed of a porous portion formed entirely on a portion of the wall portion of the housing that comes into contact with the swelling material. Here, the porous portion may have any structure as long as it can introduce the leaked substance into the housing, and may be composed of, for example, a large number of through holes penetrating the wall portion in the thickness direction, and a mesh structure or sponge. It may be in the form of a structure. Specifically, wire mesh, various porous metals such as sintered metal, various porous plastics, various cloths, and the like can be used, and porous PTFE can also be used to make them water repellent. Further, in the case where foreign matter does not accumulate in this portion, only the frame for fixing the swelling material may be used.

In the invention of claim 6, the internal space and the swelling material storage chamber are continuously provided, and the swelling material that is porous and has air permeability so that the internal space communicates with the outside of the housing is used. . As such a swelling material, a breathable foam made of a material that absorbs and swells a leaked material,
It is possible to use a porous material in which fine particles are welded or adhered, or a material which is provided with a plurality of small holes penetrating the substrate to make it porous and at the same time provide air permeability.

According to the seventh aspect of the present invention, the internal space is made airtight, and then a pressure adjusting chamber whose volume is increased / decreased according to a change in external pressure or internal pressure is provided, and the pressure adjusting chamber and the internal space are communicated with each other. .

In the invention of claim 8, an internal space and a swelling material storage chamber are continuously provided, and a swelling material is provided on the internal space side with a sealing layer that does not have air permeability and hermetically seals the internal space. And the other part is porous. As such a swelling material, use one that has a composite structure in which the side that comes into contact with the leaked substance first is made of a material that is permeable porous or has many voids, and the inner space side is a thin, bubble-free sheet. You can Examples of the composite structure include a thin sheet with a large number of protrusions, a large number of holes formed on one side of a substrate so as not to penetrate small holes, and a thin porous material with fine particles welded or bonded. There are things such as a sheet bonded.

[0025]

When the swelling material is constrained as in the first aspect of the invention, the swelling material does not move or vibrate even if vibration is applied from outside before swelling, and the swelling material expands in the inner space. Since it can be limited only to the heading direction, generation of an erroneous signal can be prevented. Further, when the leaked substance introducing portion is provided on the wall portion of the housing facing the internal space with the swelling material interposed therebetween, the swelling material can be swollen quickly in the direction toward the internal space, and the detection sensitivity of the detector is enhanced. be able to.

According to the second aspect of the invention, the light reflecting portion is located in the optical path to reflect light before the leakage is detected, and when the leakage is detected, the light non-reflecting portion is located in the optical path to detect the light. By blocking the reflection, even if a break occurs in the optical fiber, the reflection of light is eliminated as in the case of detecting the leakage, and the occurrence of abnormality can be detected.

The moving stroke of the light shielding material needs to be larger than the core diameter of the optical fiber, although it depends on the size of the internal space. As in the invention of claim 3, the light reflecting surface of the light reflecting portion has a core diameter. By setting it to 2 times or more and 20 times or less, precise positioning of the light shielding material becomes unnecessary, and a stable leak detector that is not affected by vibration, load, temperature, etc. can be obtained.

According to the fourth aspect of the invention, the swelling material is bulged at the end of the inner space of the housing on the side of the swelling material accommodating chamber so as to swell the swelling material around the portion where the shielding member is fixed. Providing the guide portion for guiding enables the shield member to be surely moved in an appropriate direction even when the shield member is fixed to the swelling material.

According to the fifth aspect of the present invention, when the leaking substance introducing portion is constituted by the porous portion which is entirely formed in the portion of the wall portion of the housing which comes into contact with the swelling material, the leaking substance is almost completely discharged from one side of the swelling material. It is possible to evenly absorb the swelling material, prevent local swelling of the swelling material from occurring, and more reliably move the shielding member in an appropriate direction.

When a swelling material that is porous and has air permeability is used as in the sixth aspect of the invention, an excessive increase in volume due to swelling can be absorbed by the voids in the swelling material that constitutes the porous material. In addition, the swelling speed can be accelerated by promoting the penetration of the leaked substance. In addition, the swelling material having air permeability,
Since it serves as an entrance and exit due to expansion and contraction due to temperature changes of the gas in the internal space where the shielding member is placed, the internal space can always be balanced with the external pressure, and deformation of the swelling material due to pressure is eliminated. .

When the inner space is made airtight (including liquidtight) as in the seventh aspect of the invention, for example, the hydrophobic organic liquid in the aqueous solution or the aqueous solution in the hydrophobic organic liquid can be detected. This is because the internal space is in an airtight state (including a liquid-tight state), so that a leaking substance or a solution does not enter the internal space to make measurement impossible or generate an erroneous signal. When the leak detector is placed in an aqueous solution and the internal space is made airtight, the external pressure changes depending on the position of the leak detector, causing deformation such that the swelling material bulges toward the inner space. Wake up. As a result, the shielding member may move to generate an erroneous signal. Further, when the pressure in the airtight internal space becomes high due to the rise in ambient temperature, the swelling material must swell against this pressure, which causes a problem that the shielding member cannot be moved sufficiently. There is a problem that this occurs or the detection sensitivity deteriorates. In the present invention, the pressure adjusting chamber whose volume is increased or decreased according to the change of the external pressure or the internal pressure is provided, and the pressure adjusting chamber is communicated with the internal space. Therefore, the swelling material is bulged toward the internal space by the external pressure. Such deformation does not occur, and even if the ambient temperature rises, the internal pressure of the internal space does not increase,
The occurrence of such a problem can be prevented.

As the swelling material according to the eighth aspect of the invention, a swelling material having a non-breathable seal layer for hermetically sealing the inner space on the inner space side and the other portion being porous is used. With this, the movement of the shielding member due to the compression of the swelling material by the external pressure can be minimized to make the internal space airtight.
Further, as in the invention of claim 6, the porous portion enables absorption of an excessive increase in volume due to swelling, promotion of permeation of a leaked substance, and acceleration of the swelling rate.

[0033]

【Example】

[Embodiment 1] An embodiment of the present invention will be described below in detail with reference to the drawings. 1A to 1C are longitudinal sectional views of the embodiment, a sectional view taken along line BB of FIG. 1A and C of FIG. 1A.
It is a -C line sectional view. In these figures, 1 is an optical fiber cable composed of an optical fiber 2 composed of a multimode optical fiber having a core diameter of 50 μm and a cladding diameter of 125 μm, and an outer sheath 3 having a diameter of 2.8 mm covering the optical fiber 2. Is. The outer sheath 3 at the tip of the optical fiber cable 1 is removed, and the base of the optical fiber 2 on the outer sheath 3 side exposed by removing the outer sheath 3 is a cone-shaped plug 4 made of epoxy resin formed by transfer molding. Is covered with. The cone-shaped plug 4 is used to increase the positioning accuracy of the optical fiber cable 1 with respect to the rigid support 5, and has a truncated cone shape whose diameter decreases toward the tip. A ceramic ferrule 6 made of ceramics is fitted to the portion of the optical fiber 2 protruding from the cone-shaped plug 4 with an adhesive. Further, in order to reduce the coupling loss, the tip of the optical fiber 2 is polished.

The rigid support base 5 is manufactured by molding epoxy resin, and the rigid support base 5 has a fitting hole 7 into which the cone-shaped plug 4 and the ferrule 6 are fitted, and a core of the optical fiber 2. An internal space 8 whose end face is exposed and a recess 10a for forming a swelling material storage chamber 10 in which a swelling material 9 is stored are formed. Actually, the swelling material storage chamber 10 is configured in a state where the rigid support base 5 is inserted into the stainless steel holder 11 and the stainless steel sintered metal cover 12 is fitted into the holder 11. .

The cone-shaped plug 4 and the ferrule 6 are inserted and fixed in the fitting hole 7 of the rigid support base 5 with an adhesive agent. The internal space 8 extends in a direction (hereinafter, referred to as an orthogonal direction) orthogonal to a direction in which the optical axis of the optical fiber 2 extends (hereinafter, referred to as an optical axis direction).
And a second space 8b located on the swelling material storage chamber 10 side and extending in the optical axis direction. The first space 8a is formed in such a shape that the plate-shaped shield member 13 fixed to the swelling material 9 can move smoothly, and the second space 8b is centered on the portion where the shield member 13 is fixed. Become swelling material 9
Is formed in a shape that guides the swelling material 9 so as to swell. The swelling material storage chamber 10 in which the swelling material 9 is stored is
It is formed by being surrounded by the inner wall surface of the recess 10a, the inner wall surface of the cover 12, and the inner wall surface of the holder 11, and prevents the swelling material 9 from moving before swelling and the swelling material 9 swells toward the internal space 8. The structure is such that the swelling material is restrained. When the cover 12 is attached, the swelling material 9 is pressed or compressed in the orthogonal direction and stored in the swelling material storage chamber 10.

In this embodiment, a breathable foam of polyisoprene rubber is used as the swelling material 9. This swelling material has a property of swelling when absorbing a hydrophobic organic liquid and a low boiling point organic substance vapor, and has air permeability in the thickness direction (orthogonal direction). Therefore, in this embodiment, the internal space 8
Communicate with the external space through the swelling material 9.

The holder 11 has a tubular shape with both ends in the optical axis direction being open and a rectangular cross section. The holder 11 has a fitting portion 1 into which the cover 12 is fitted.
1a is formed. The rigid support 5 is fitted inside the holder 11 via an adhesive, and an epoxy resin is filled in the opening 11b of the holder 11 where the end of the rigid support 5 on the fitting hole 7 side is located. It is filled and the sealing part 14 is formed. In this embodiment, the rigid support 5 and the sealing portion 1
A holding portion for holding the optical fiber is constituted by 4, and a housing is constituted by the holder 11, the cover 12, a part of the rigid support 5 and the sealing portion 14. The cover 12 has an inner space 8 with a swelling material 9 interposed therebetween.
And part of the wall of the housing. The cover 12 may have a porous portion forming a leaking substance introducing portion for introducing the leaking substance, at least at a portion in contact with the one end surface 9a positioned in the orthogonal direction of the swelling material 9. The swelling speed of the swelling material 9 can be maximized by forming the leaking substance introducing portion in the entire portion of the cover 12 that contacts the end surface 9a of the swelling material 9. In this embodiment, the cover 1
Although 2 is fixed to the holder 11 with an adhesive, the cover 12 may be detachably attached to the holder 11 so that the swelling material can be replaced according to the leak substance to be detected.

The shielding member 13 has an epoxy resin on the other end surface 9b of the swelling material 9 which is located in the orthogonal direction so that it moves in the orthogonal direction orthogonal to the optical axis with a small gap from the end surface of the core of the optical fiber 2. It is fixed using resin. The light non-reflecting portion 13b is arranged on the swelling material 9 side, and
a is disposed on the tip side. The shielding member 13 has a light reflecting portion 13a and a light non-reflecting portion 13b on the surface on the optical fiber 2 side. In this embodiment, a light reflecting portion 13a is formed by vapor-depositing aluminum on a rectangular stainless steel plate, and an epoxy resin mixed with carbon fine powder is coated on the other portion to form a light absorbing light non-reflecting portion 13b. did.

The size and positional relationship between the light reflecting portion 13a and the light non-reflecting portion 13b are such that the light reflecting portion 1 before the swelling material 9 swells.
3a is located in the optical path of the light emitted from the core of the optical fiber 2, reflects the incident light toward the end surface of the core of the optical fiber 2, and when the swelling material 9 swells, the light non-reflecting portion 13b enters the optical path. The size and the positional relationship are such that the incident light is positioned so as not to reflect the incident light toward the end surface of the core of the optical fiber 2. The area of the light-reflecting surface of the light-reflecting portion 13a is preferably not less than 2 times and not more than 20 times the area of the end surface of the core about the optical axis of the light incident from the core of the optical fiber 2. In the present embodiment, specifically, a length of 10 times the core diameter of the optical fiber 2 with respect to the optical axis is used as the light reflecting surface, and the outside thereof is used as the light absorbing surface.

When various hydrophobic organic liquids such as gasoline, kerosene, heavy oil, lubricating oil, benzene and trichloroethylene, or aqueous solutions or vapors containing them enter the swelling material storage chamber 10 through the cover 12, the swelling material 9 leaks out. Absorbs substances and swells. Since the swelling material storage chamber 10 restrains the swelling material 9 in a direction in which the swelling material 9 expands toward the internal space 8, the swelling material 9 expanded by the swelling expands into the second space 8b of the internal space 8. Put out. Since the second space 8b forming the guide portion guides the swelling material 9 so that the swelling material 9 swells around the portion where the shielding member 13 is fixed, the shielding member 13 is orthogonal to the second space 8b. Move smoothly in the direction. When the shielding member 13 moves in the orthogonal direction due to the absorption of the leaked substance and the light non-reflecting portion 13b comes to be positioned in the optical path, the light is not reflected to the core of the optical fiber 2 and the leak is detected.

As a leak detection system for determining the presence / absence of leak using the leak detector of the present invention, for example, a system having the configuration shown in FIG. 2 can be used. In FIG.
21a and 21b are leak detectors, and these leak detectors 21a and 21b are the optical connectors 22.
It is connected to the optical fiber branching switch 23 via a and 22b. The optical fiber branching switch 23 has a light source 2 composed of a light emitting diode through an optical fiber line 24.
Light is supplied from 5. A beam splitter 26 is disposed adjacent to the light source 25 on the incident light side of the optical fiber line 24. The beam splitter 26 disperses the reflected light from the shielding member 13, and the signal processor 27 having the Si-APD as a light receiving element determines the presence or absence of the reflected light.
Using this system, leak detectors 21a and 21b
As a result of a test in which various kinds of hydrophobic organic liquids were brought into contact with, it was confirmed that the signal processor 27 caused no reflected light.

In the above embodiment, the housing is composed of the holder 11, the cover 12, a part of the sealing portion 14 and a part of the rigid support base 5. However, the holder 11 is formed in a box shape and the housing is composed of only the holder. May be configured. Further, in the above embodiment, the cover 12 is provided with the leaking substance introducing portion. However, without using the cover 12, a large number of through holes are directly formed in the holder to provide the leaking substance introducing portion on the wall portion of the housing. You can also

[Embodiment 2] Next, an embodiment of the invention described in claim 7 will be described in detail with reference to FIG. Figure 3 (A)
Is a vertical sectional view of the leak detector of the embodiment, and FIG. 3B is a sectional view taken along line BB of FIG. In addition, in FIG.
The same members as those shown in FIG. 1 are denoted by the same reference numerals as those in FIG. 1 plus 100. The optical fiber cable 101 used in this embodiment is the same as the cable shown in FIG. 1, but is different in that a ceramic ferrule 106 is fitted over the entire portion of the optical fiber 102 from which the outer cover 103 is removed. Further, the rigid support base 105 is configured by joining an epoxy resin half portion 105a and a half portion 105b using an epoxy adhesive. The rigid support 105 has a fitting hole 10 into which the ferrule 106 is fitted.
7, an internal space 108 where the end face of the core of the optical fiber 102 is exposed, and a swelling material storage chamber 110 in which the swelling material 9 is stored.
And a communication passage 116 are formed. Rigid support 10
The ferrule 106 is inserted and fixed in the fitting hole 107 of No. 5 via an adhesive, and the end face of the optical fiber and the end face of the ferrule 106 are ground so as to be flush with the side face of the rigid support 105. is there. The second space 108b forming the guide portion of the internal space 108 is the first space 108a.
It has a taper whose cross-sectional area becomes smaller as it goes to. Due to this taper, when the swelling agent 109 swells,
The swelling agent 109 surely swells around the portion where the shielding member 113 is attached. The communication passage 116 has the internal space 10
8 of the first space 108a and the bag body 1 forming a pressure adjusting chamber
It is provided so as to communicate with 15.

The holder 111 has a tubular shape whose one end in the optical axis direction is closed by the wall 111b and whose cross-sectional shape is rectangular. In the holder 111, the rigid support 105 is located between the wall 111b and the pressure support chamber 11
5 are fitted so as to form a storage space 117 for storing 5. The storage space 117 communicates with the space outside the holder 111 through the porous portion of the cover 112.
The bag 115 that constitutes the pressure adjusting chamber has a structure formed in an accordion shape using an impermeable polyethylene film. The peripheral edge of the opening of the bag 115 is airtightly joined to the wall surface of the rigid support 105 through an appropriate fixing means such as an adhesive. In addition, the structure of the pressure adjusting chamber is such that the internal space 1 is breathed by external pressure or the volume is changed according to the change of internal pressure.
Any shape or structure may be used as long as the inner pressure and the outer pressure of 08 can be equalized and the deformation of the swelling material 109 can be suppressed.

The swelling material 109 includes a plurality of small holes 109c having a bottom from one surface 109a side in the polyisoprene rubber sheet.
It is formed by opening a large number of ... And the swelling material 10
9 is a surface 109b on the side where the small holes 109c are not formed.
Is housed in the swelling material housing chamber 110 with the side facing the inner space 108. The restraint relationship between the swelling material 109 and the swelling material storage chamber 110 is the same as the restraint relationship between the swelling material 9 and the swelling material storage chamber 10 of the first embodiment.
The surface 109b of the swelling material 109 is bonded to the bottom of the recess 110a of the rigid support 105 using an adhesive to keep the internal space 108 airtight (liquid-tight). A blocking member 113 is fixed to the surface 109b of the swelling material 109. The configuration of the blocking member 113 is the blocking member 13 of the first embodiment.
Is the same as. In this embodiment, a part of the swelling material 109 has a non-air-permeable structure to make the internal space 108 in an airtight (including liquid-tight) state. However, apart from the swelling material 109, it is made of a stretchable synthetic resin or rubber. Of the deformable seal sheet is adhered to the bottom of the recess 110a to make the internal space 108 airtight, and the swelling material having air permeability similar to the swelling material 9 used in Example 1 is accommodated on the inner space 108. Good. In this case, the shielding member may be fixed to the back surface of the seal sheet. Further, in this embodiment, the small holes 109c ... Are provided in the swelling material 109 in order to increase the swelling speed of the swelling material 109, but the swelling material 109 is not provided with the small holes 109c.
Of course, the whole may be non-breathable porous.

In the leak detector of this embodiment, the internal space 10
Since 8 can be configured to be airtight (liquid-tight) and the internal pressure of the internal space can be adjusted, it is possible to detect a specific leak substance in the liquid without trouble.

[0047]

According to the invention of claim 1, the swelling material does not move or vibrate even when vibration is applied from the outside,
Further, since the expansion direction of the swelling material can be limited to only the direction toward the internal space, it is possible to prevent the generation of an erroneous signal. Further, when the leaked substance introducing portion is provided on the wall portion of the housing facing the internal space with the swelling material interposed therebetween, the swelling material can be swollen quickly in the direction toward the internal space, and the detection sensitivity of the detector is enhanced. There is an advantage that can be.

Further, according to the invention of claim 2, there is an advantage that not only the detection of the leakage but also the occurrence of the disconnection of the optical fiber can be detected.

According to the invention of claim 3, there is an advantage that a precise positioning of the light shielding material is not necessary and a stable leak detector which is not affected by vibration, load, temperature and the like can be obtained.

According to the invention of claim 4, there is an advantage that the shielding member can be surely moved in an appropriate direction even when the shielding member is fixed to the swelling material.

According to the fifth aspect of the present invention, the leaked substance can be absorbed substantially evenly from the one surface side of the swelling material, and the swelling of the swelling material can be prevented from being locally biased and shielded. There is an advantage that the member can be more surely moved in an appropriate direction.

According to the sixth aspect of the present invention, the excessive volume increase due to the swelling can be absorbed by the voids in the swelling material that constitutes the porous material, and further the permeation of the leaking substance is promoted to increase the swelling speed. There is an advantage that can be accelerated. Moreover, the swelling material having air permeability serves as an entrance and exit due to expansion and contraction due to temperature changes of the gas in the internal space where the shielding member is arranged, so that the internal space can always be balanced with the external pressure, It is possible to eliminate the deformation of the swelling material.

According to the invention of claim 7, since the internal space is made airtight (including liquidtight), there is an advantage that the hydrophobic organic liquid in the aqueous solution or the aqueous solution in the hydrophobic organic liquid can be detected. . Further, according to the present invention, the pressure adjusting chamber whose volume is increased or decreased according to the change of the external pressure or the internal pressure is provided, and the pressure adjusting chamber and the internal space are communicated with each other. There is an advantage that the deformation such as bulging does not occur, the internal pressure of the internal space does not increase even when the ambient temperature rises, and an erroneous signal can be prevented.

According to the invention of claim 8, as the swelling material, a swelling material which is not breathable and which has a seal layer for hermetically sealing the internal space on the internal space side and the other parts being porous is used. Therefore, there is an advantage that the movement of the shielding member due to the compression of the swelling material by the external pressure can be minimized to make the internal space airtight.

[Brief description of drawings]

1A is a vertical cross-sectional view of an embodiment of the present invention, FIG. 1B is a cross-sectional view taken along line BB of FIG. 1A, and FIG. 1C is C of FIG. 1A.
It is a -C line sectional view.

FIG. 2 is a block diagram showing the configuration of an example of a leak detection system that determines the presence or absence of leak using the leak detector of the present invention.

3A is a vertical cross-sectional view of a leak detector according to another embodiment of the present invention, and FIG. 3B is a cross-sectional view taken along line BB of FIG. 3A.

[Explanation of symbols]

 1, 101 Optical fiber cable 2, 102 Optical fiber 3, 103 Exterior coating 4 Cone-shaped plug 5, 105 Rigid support 6, 106 Ferrule 7, 107 Fitting hole 8, 108 Internal space 9, 109 Swelling material 10, 110 Swelling Material storage space 11,111 Holder 12,112 Cover 13,113 Shielding member 14,114 Sealing portion 115 Bag body (pressure adjusting chamber) 116 Communication passage

Claims (8)

[Claims] 1. A housing, an optical fiber whose end portion is held by a holding portion provided inside the housing, and which radiates light from an end surface of a core into an internal space of the housing, and which is provided on a wall portion of the housing. A leaking substance introducing section, a swelling material disposed in the swelling material accommodating chamber provided in the housing and absorbing and swelling the leaking substance to be detected entered from the leaking substance introducing section, and swelling of the swelling material To move in the internal space,
The swelling material comprises a shielding member that positions a light reflecting portion or a light non-reflecting portion in an optical path of light emitted from the core when the swelling material is stored in the swelling material storage chamber before swelling. The swelling material has a structure that restrains the movement and restrains the swelling material so that the swelling material swells toward the inner space, and the leakage substance introducing portion faces the inner space with the swelling material in between. The leak detector is provided on a wall portion of the housing. 2. The shielding member has a light reflecting portion and a light non-reflecting portion, and the light reflecting portion and the light non-reflecting portion have the optical path before the swelling material swells. A position inside which reflects incident light toward the end surface of the core, and when the swelling material swells, the light non-reflecting portion is located in the optical path and does not reflect incident light toward the end surface of the core. The leak detector according to claim 1, wherein the leak detector is arranged in a relationship with the shield member. 3. The light-reflecting portion is at least twice the area of the end face of the core about the optical axis of the light incident from the core.
The leak detector according to claim 2, wherein the leak detector has a light reflecting surface having an area of 0 times or less, and the light non-reflecting portion is arranged outside the light reflecting surface. 4. The shielding member is fixed to the swelling material, and a portion to which the shielding member is fixed is centered at an end portion of the internal space on the swelling material storage chamber side. The leak detector according to claim 1, further comprising a guide portion that guides the swelling material so that the swelling material swells. 5. The swelling material is stored in the swelling material storage chamber in a state of being pressed by the wall portion of the housing where the leaking substance introducing portion is provided, and the leaking substance introducing portion is the wall portion. The leak detector according to claim 1, wherein the leak detector is formed of a porous portion formed entirely in a portion that comes into contact with the swelling material. 6. The internal space and the swelling material accommodating chamber are continuously provided, and the swelling material is porous and has air permeability so that the internal space communicates with the outside of the housing. The leak detector according to claim 1, 2, 3, 4 or 5. 7. A housing, an optical fiber whose end portion is held by a holding portion provided inside the housing to radiate light from an end surface of the core into an internal space of the housing, and which is provided on a wall portion of the housing. And a swelling material that is disposed in the swelling material accommodating chamber provided in the housing and swells when absorbing the leaking material to be detected that has entered from the leaking material introduction portion, and uses the swelling of the swelling material And move in the internal space,
A shielding member for positioning a light reflecting portion or a light non-reflecting portion in the optical path of the light emitted from the core when the swelling material swells, and the internal space is configured in an airtight state, The swelling material accommodating chamber has a structure that prevents the swelling material from moving before swelling and restrains the swelling material so that the swelling material swells toward the internal space. A leak detector characterized in that a pressure adjusting chamber whose volume is increased or decreased is further provided, and the pressure adjusting chamber and the internal space communicate with each other. 8. The internal space and the swelling material storage chamber are continuously provided, and the swelling material does not have air permeability, and a sealing layer for hermetically sealing the internal space is provided on the internal space side. 8. The leak detector according to claim 7, wherein the leak detector is provided in the first part and the other part is porous.