JPH08233726A - Optical fiber liquid sensor and swelling member therefor - Google Patents

Abstract

PURPOSE: To obtain an optical fiber liquid sensor and swelling member therefor in which stabilized loss increase characteristics can be attained for optical fiber while enhancing the productivity and lowering the manufacturing cost. CONSTITUTION: When an optical fiber 7 swells with a liquid to be detected from a swelling member 3, transmission loss of the optical fiber 7 is increased and the presence of liquid is detected. In such an optical fiber liquid sensor, the swelling member 3 comprises layers 3A swelling with the liquid to be detected and layers 3B for conducting the liquid laminated alternately. Each layer is bonded or fused to provide an integral laminate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber liquid sensor for detecting a liquid such as water or oil and a swelling member thereof.

[0002]

2. Description of the Related Art Conventionally, as an optical fiber liquid sensor of this type, for example, there is one described in Japanese Patent Laid-Open No. 63-228105. This optical fiber liquid sensor is configured to detect a liquid by using a swelling material that expands in volume when brought into contact with a liquid such as water or oil as a liquid to be detected.

Specifically, the swelling member is molded and housed in a liquid-permeable container of the optical fiber liquid sensor, and the optical fiber for detection is housed in the container. The liquid sensor is inserted and configured as a liquid sensor.

When the optical fiber liquid sensor thus constructed is immersed in the liquid to be detected, the liquid to be detected permeates into the container, and the swelling member is expanded by the liquid to be detected and inserted into the container. The liquid is detected by causing a bend in the optical fiber and increasing the transmission loss of the optical fiber. When the swelling member is in the form of one lump in this way, the liquid that has entered the container is absorbed only from the outer surface of the swelling member, so that the swelling speed is slow, and the infiltration of the liquid until the occurrence of bending of the optical fiber occurs. There is a problem that it takes time and the infiltration of the liquid cannot be instantly detected.

In order to solve such a problem, it is necessary to divide the swelling member to increase the surface area and to quickly permeate the liquid between the divided swelling members. As one method, there is a method in which a swelling material in the form of fine particles is contained in a container to form a swelling member. in this way,
A part of the swollen portion is consumed to fill the space between the particles, the conversion efficiency into the force for bending the optical fiber is poor, and the transmission loss does not increase remarkably.

As a method for solving this problem, an optical fiber liquid sensor previously filed by the applicant of the present invention (Japanese Patent Application Laid-Open No. Hei 3 (1998)).
-197844). In this product, a swelling member is divided into a plurality of flakes that are in close contact with each other on the surface to form a swelling material. Separately, a thin piece of a liquid-conducting material that conducts liquid is prepared and formed into a liquid-conducting material. The material and the liquid-conducting material are alternately and closely stacked and housed in a container to form a swelling member. In the optical fiber liquid sensor having such a configuration, the liquid is quickly introduced into the swelling material by being guided to the liquid guiding material between the swelling materials. Then, the liquid is quickly absorbed by the swelling material from a large area. Since each swelling material is densely overlapped with the liquid conducting material, the swelling of each swelling material appears as an expansion of the entire swelling member, causing the optical fiber to bend strongly,
A significant transmission loss can be obtained.

[0007]

However, in the above-mentioned conventional optical fiber liquid sensor, since the swelling member is divided into the flaky liquid guiding material and the swelling material, all of them have exactly the same size. It has been found that there is a new problem in that productivity is poor and manufacturing cost is increased because it is necessary to cut it, and it is necessary to devise so that each thin piece does not fall apart during the work of assembling into the container. It was also found that if the shape of the swelling member is not uniform, the expansion at the time of liquid penetration becomes unstable and the loss increasing characteristic of the optical fiber tends to become unstable.

The present invention has been made in view of the above circumstances, and is an optical fiber liquid sensor having a fast response, a stable loss increasing characteristic, and good productivity, a swelling member thereof, and a method of manufacturing a swelling member. The purpose is to provide.

[0009]

In order to achieve the above-mentioned object, the first invention of the present application is that the optical fiber is deformed by the swelling of the swelling member by the liquid to be detected, and the transmission loss of the optical fiber increases, so that the object to be detected is increased. In the optical fiber liquid sensor for detecting the presence of a liquid, the swelling member is configured by alternately laminating a swelling layer that swells with the liquid to be detected and a liquid conducting layer that conducts the liquid to be detected, and the layers are bonded to each other. The gist of the present invention is that all layers are integrated by being fused or fixed.

The second invention of the present application is constructed by alternately laminating a plurality of swelling layers and liquid-conducting layers, and by bonding, fusing or fixing each layer, all layers are integrated. The gist of the present invention is to form a laminate having the above structure into a predetermined shape.

Further, the third invention of the present application is constituted by laminating a swelling layer and a liquid-conducting layer in a concentric or spiral shape, and by adhering, fusing or fixing each layer, all layers are integrated. The gist of the present invention is to form a laminate having the above structure into a predetermined shape.

Further, in the fourth invention of the present application, the periphery of the laminated body formed by laminating the swelling layer and the liquid conducting layer is surrounded by the liquid conducting layer and adhered, fused or fixed to the laminated body. Therefore, the gist is that all layers are configured so as to be integrated.

Further, the present invention is manufactured by the following manufacturing method.

First, when laminating a plate-shaped or sheet-shaped swelling material that swells with a liquid to be detected and a plate-shaped or sheet-shaped liquid-conducting material that conducts the liquid to be detected, the entire laminating surface is laminated. Alternatively, an adhesive layer is formed by partially adhering, fusing or adhering between the layers, and the layers are laminated so as to be integrated, and then the laminate is formed into a predetermined shape.

When a plate-shaped or sheet-shaped swelling material that swells with the liquid to be detected and a plate-shaped or sheet-shaped liquid-conducting material that conducts the liquid to be detected are laminated, the entire surface of the laminated surface Alternatively, one part may be laminated while forming an adhesive layer by bonding, fusing or adhering each layer.
After forming a laminated body of layers, an adhesive layer is formed on one surface of the laminated body, and the laminated body is spirally wound so that the surface is the inside, and is formed into a predetermined shape.

The adhesive layer is made of an adhesive.

Further, the adhesive layer is formed by the fusing property of one of the swelling material and the least of the liquid conducting material.

Further, heating may be performed when the laminated body is integrally formed.

[0019]

According to the first invention of the present application, the swelling member is constituted by alternately stacking a swelling layer that swells with the liquid to be detected and a liquid-conducting layer that conducts the liquid to be detected, and the layers are bonded or fused. Alternatively, since all the layers are integrated by being fixed, all the swelling of the swelling layer appears as the expansion of the entire swelling member, and the optical fiber of the optical fiber liquid sensor is strongly bent to be clear. Result in increased loss.

The second invention of the present application is constituted by alternately laminating a plurality of swelling layers and liquid-conducting layers, and by bonding, fusing or fixing the respective layers, all layers are integrated. Since each swelling layer has a larger area than the thickness, the liquid that has been guided to the liquid-conducting layer and permeated between the swelling layers is quickly absorbed from the large area by the swelling layer. Then, the swelling layer swells immediately. In addition, the integrally molded swelling member is easy to process into a predetermined shape,
The work of assembling the sensor in the container is good, the productivity is improved, and the manufacturing cost is improved. Further, the shape of the swelling member is stable, and as a result, the expansion at the time of infiltration of the liquid is stable, the loss increasing characteristic of the optical fiber is also stable, and the reliability of the sensor can be improved.

In the third invention of the present application, the swelling layer and the liquid conducting layer are concentrically or spirally laminated and integrally molded. That is, in the form in which the swelling layer and the liquid-conducting layer are alternately laminated in multiple layers, a planar laminated form, a concentric circular or spiral laminated form, and other curved surface laminated forms are conceivable. The optimal stacking form can be selected depending on the structure of the container of the sensor, the structure for transmitting the liquid, the mechanism for increasing the loss, etc. Also, the container of the optical fiber liquid sensor has a cylindrical shape and the liquid has a cylindrical shape. It is suitable for a sensor with a structure that cannot penetrate only from the bottom of the container.

Further, according to the fourth invention of the present application, since the periphery of the laminated body formed by laminating the swelling layer and the liquid conducting layer is surrounded by the liquid conducting layer and integrally molded, the swelling layer and the sensor are formed. It is possible to prevent close contact with a member such as a container, and prevent problems such as the swollen swelling layer closing the liquid-permeable holes provided in the container or the like of the sensor, which further effectively acts on the above problems.

When laminating a plate-shaped or sheet-shaped swelling material that swells with the liquid to be detected and a plate-shaped or sheet-shaped liquid-conducting material that conducts the liquid to be detected, the entire laminated surface Alternatively, a method of forming an adhesive layer by adhering, fusing or adhering each layer in a part and laminating the layers so as to be integrated, and then molding the laminated body into a predetermined shape is the shape and size of each layer. Also, the swelling layer and the liquid-conducting layer, which have the same overall shape and size, are laminated alternately in a multi-layered structure in a plane to easily and economically manufacture the swelling member.

Further, the adhesive layer is bonded by an arbitrary adhesive,
It is composed by fusing or adhering, and in addition to synthetic resin adhesives, if at least one of the swellable material and the liquid-conducting material has adhesiveness due to the addition of water, it is simply water. May be

Further, since the adhesive layer is formed by the fusible property of either the swelling material or the liquid conducting material, the adhesive layer can be manufactured without using an adhesive. Can be simplified and workability is improved. Further, as another method for integrally forming the swelling layer and the liquid-conducting layer so as to form one lump, there is a method of sewing the swelling layer and the liquid-conducting layer with a thread. The optimum method may be selected depending on the characteristics of the liquid to be detected, the structure of the sensor, and the like.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

First, the first embodiment will be described.

FIG. 1 is a sectional view of the optical fiber liquid sensor before the liquid to be detected enters, and FIG. 2 is a sectional view of the optical fiber liquid sensor after the liquid to be detected enters and the swelling member swells.
FIG. 3 is an enlarged cross-sectional view of the swelling member.

As shown in FIG. 1, the optical fiber liquid sensor has a flat rectangular parallelepiped container 1 made of plastic, a guide member 2 at both lower ends thereof, and a swelling member 3 therebetween.
However, the stress applying member 4 is housed above it, and the receiving member 5 is housed thereabove, and is sandwiched between the stress applying member 4 and the receiving member 5 through the insertion hole 6 formed in the container 1. The optical fiber 7 is inserted and assembled.

Liquid-permeable holes 8 are provided on both side surfaces of the container 1 so that the location where the swelling member 3 is disposed communicates with the outside to allow the liquid to enter. A pressing portion 9 that bulges in a mountain shape is formed on the optical fiber 7 side of the stress applying member 4, and a valley portion 10 is formed on the optical fiber 7 side of the receiving member 5 so as to correspond to the mountain shaped pressing portion 9. Has been done. Guide member 2
Is for guiding the operations of the swelling member 3 and the stress applying member 4 in a direction orthogonal to the axis of the optical fiber 7.

Here, the swelling member 3 is, as shown in FIG.
Five swelling layers 3A and four liquid-conducting layers 3B are alternately laminated one by one and integrally molded to form one lump,
After that, the swelling layer 3A and the liquid conducting layer 3B are surrounded by the container 1, the guide member 2, and the stress applying member 4 such that the stacking direction of the swelling layer 3A and the liquid conducting layer 3B coincide with the stress applying direction to the optical fiber 7, that is, the moving direction of the stress applying member 4. It is processed into a flat rectangular parallelepiped with a predetermined size so that it can be housed in the expanded swelling member housing portion 11 without a gap.

As a material for the swelling layer 3A, a swelling material that absorbs a liquid to be detected and causes volume expansion is used.
It is appropriately selected and used depending on the type of liquid such as water or oil. If the liquid to be detected is water, acrylic acid
Water-absorbing polymers such as vinyl alcohol copolymers, acrylic acid polymers, acrylic acid-acrylamide copolymers, polyethylene oxide metabolites, carboxycellulose-acrylic acid graft polymers, starch graft polymers, and such water-absorbing polymers And a swellable material such as a mixture of a thermoplastic resin and a thermoplastic elastomer is used. When the object to be detected is oil such as petroleum, ethylene-olefin compound such as ethylene propylene rubber (EP rubber), styrene-ethylene-butylene-styrene (SE
Bs) compounds, ethylene-ethyl acrylate, ethylene-vinyl acetate and other compounds are suitable as swelling materials. In the EP rubber and the like, the degree of crosslinking is adjusted,
By adding carbon black or the like to obtain a material having a large expansion degree due to oils, a better material can be obtained.

The liquid-conducting layer 3B is for guiding the liquid to be detected to the swelling layer 3A and widely spreading it on the surface thereof, and is a paper made of a material stable to the liquid to be detected.
Cloth, synthetic resin film, metal foil and the like are suitable. Among these materials, when a liquid-permeable material such as paper or cloth is used as the liquid guide layer 3B, the liquid outside the swelling member 3 is absorbed and diffused in the liquid guide layer 3B. The liquid is absorbed from the liquid guiding layer 3B into the swelling layer 3A.

Thus, the liquid-conducting layer 3 is provided between the swelling layers 3A.
By interposing B, the liquid outside the swelling member 3 can be guided between the layers of the respective swelling layers 3A and absorbed by the swelling layer 3A in a large area. Moreover, each swelling layer 3
By interposing the liquid-conducting layer 3B between the layers of A, the swelling layers 3A are in close contact with each other and the layers of the swelling layer 3A are closed, and the liquid absorption rate does not decrease.

The method of laminating the swelling layer and the liquid-conducting layer and integrally molding them to form one lump includes a method of adhering and integrating with an adhesive, or at least one of the swelling layer and the liquid-conducting layer. There is a method of fusion-bonding integration using a fusible material on one side, a method of physically fixing and fixing the swelling layer and the liquid-conducting layer, and the like. Characteristics of
The optimum method may be selected depending on the structure of the sensor.

Depending on the type of adhesive, it may be dried naturally without heating. Further, instead of applying the adhesive between the layers, a thin sheet-shaped adhesive may be inserted between the layers.

Here, a method of integrally bonding the swelling member 3 with an adhesive will be described. FIG. 16 is a flowchart showing the procedure for producing the swelling member according to the present invention.
Referring to FIG. 16, in step S11, a predetermined number of sheet-shaped swellable materials as the swelling layer 3A and a predetermined number of sheet-shaped liquid-conducting materials as the liquid guiding layer 3B are prepared, and both of them are prepared. A thin adhesive is applied to the whole or a part of the boundary surface, and they are alternately superposed and closely adhered to each other.
After that, in step S13, it is placed in a heating oven and heated to be bonded to form the whole laminated body having a multilayer structure into one body, and then in step S15, it is punched and formed with a die having a predetermined shape. Adhesives include various types of glue, thermosetting adhesives, thermoplastic adhesives, synthetic rubbers, and the like. The optimum adhesive may be selected depending on the characteristics of the swelling material and the liquid conducting material, the characteristics of the liquid to be detected, and the like.

Next, a method of fusion-bonding the swelling member 3 using a fusible material will be described. Examples of the material having the fusing property include a heat fusing material and a self-fusing material. A thermoplastic polymer material or the like has a heat-fusible property, and a material containing a thermoplastic polymer material or the like as a component of the swelling material or the liquid-conducting material is a heat-fusible material,
It can be used as a swelling member. Also, some water-swellable swellable materials have a self-fusion property when the water-swellable component contained therein swells only in the surface part and becomes sticky when heated by impregnating a small amount of water. Therefore, it can be used as a fusible material.

Here, the swelling member 3 is made of a heat-fusible material.
A method of manufacturing by fusion-melting and integrating will be described. FIG.
7 is a flow chart showing an example of a manufacturing procedure of a method for manufacturing the swelling member 3 by fusion-bonding them together. Referring to FIG. 17, in step S21, a predetermined number of sheet-shaped heat-fusible swelling materials as the swelling layer 3A and a predetermined number of sheet-shaped liquid-conducting materials as the liquid guiding layer 3B are prepared. And then stack them alternately and closely, and then
In step S23, after putting in a heating oven and heating and fusing to form the whole laminated body of the multilayer structure into one body,
In step S25, it is manufactured by punching with a mold having a predetermined shape. The liquid-conducting material may have a heat-melting property, and both the swelling material and the liquid-conducting material may have a heat-bonding property.

As another method of laminating the swelling layer and the liquid-conducting layer and integrally molding them to form one lump, there is a method of fixing the expanding layer and the liquid-conducting layer to be integrated. In this method, a plate-shaped or sheet-shaped swellable material and a liquid-conducting material are prepared, punched and molded in a mold of a predetermined size first, and then laminated in a predetermined laminated body, and then the whole is laminated. This is a method of physically fixing them by stitching them with threads and integrating them. Even in the method of adhesively integrating using the above-mentioned adhesive or the method of fusion-bonding using a fusible material, depending on the material, it may be punched and molded in a mold of a predetermined size. It is also possible to manufacture by integrally adhering or fusing after being laminated on the laminated body.

1 and 2 show the process in which the liquid to be detected enters and the swelling member swells and the optical fiber liquid sensor operates.
Will be explained. A plurality of vertical groove-shaped liquid permeation holes 8 are formed on the wall surface of the container 1 corresponding to the swelling member accommodation portion 11 so as to face the laminated surface of the swelling member 3. When the liquid infiltrates through the liquid permeation holes 8, the liquid is guided to the liquid guiding layer 3B and diffuses, and the liquid is quickly absorbed by the large area of each swelling layer 3A. Then, each swelling layer 3A swells and the swelling member 3 expands rapidly. Due to the expansion of the swelling member 3, the stress applying member 4 is moved to the optical fiber 7 side, and as a result, the stress applying member 4 pushes the optical fiber 7 to bend the optical fiber 7.
The transmission loss will increase. Then, by detecting the increase of the transmission loss of the optical fiber 7 by measuring the decrease of the outgoing light level of the transmitted light of the optical fiber 7 or the change of the backscattered light intensity, it is possible to detect the presence or absence of liquid infiltration.

Next, a second embodiment of the swelling member will be described with reference to FIG.

FIG. 4 is an enlarged sectional view showing the structure of the swelling member in the optical fiber liquid sensor according to the second embodiment of the present invention. The swelling member 21 shown in FIG.
In the same manner as the swelling member 3 shown in FIG. 3 of the embodiment, after the liquid guiding layer 3B is laminated between the five swelling layers 3A, the laminated body is surrounded by the liquid guiding layer 21B and integrally molded. There is. The liquid guide layer 21B may be provided so as to cover the entire laminated body, or may be provided in a state where a part of the upper surface or the like is cut off. Further, the liquid guide layer 21B is stable against the liquid to be detected,
A material similar to the liquid-conducting layer 3B having liquid permeability that guides the external liquid to be detected to the internal laminate is used.

The swelling member 21 has substantially the same effect as that of the first embodiment, and the swelling member 21 is formed by integrally molding the periphery of the laminated body with the liquid guide layer 21B to form the swelling layer. 3A and other members in the container 1 can be prevented from adhering to each other, and problems such as the swollen swelling layer 3A closing the insertion hole 3 can be prevented. This swelling member 21 can be used in the same optical fiber liquid sensor as in FIG. 1 of the first embodiment. For example, by using it instead of the swelling member 3 of the optical fiber liquid sensor in FIG. The characteristics can be improved.

The swelling member 21 is bonded and integrated by using an adhesive, or is melted and integrated by using a fusible material for at least one of the swelling layer and the liquid conducting layer. By physically fixing and fixing the whole,
It is manufactured by a method similar to that of the first embodiment.

According to the method of bonding and integrating using an adhesive, for example, a thin sheet-shaped liquid-conducting material is prepared and a thin adhesive is applied to the entire one surface, and the surface to which the adhesive is applied is set to the inside. It is manufactured by wrapping the swelling member 2 manufactured by the method of the first embodiment, cutting an unnecessary portion to form it, and then placing it in a heating oven and heating it to bond the whole. Alternatively, from a sheet-shaped swellable material and a liquid-conducting material,
The swelling layer, the liquid-conducting layer, and the liquid-conducting layer that surrounds the periphery of the laminate are cut into a predetermined shape for each layer, and then an adhesive is applied to a part of the boundary surface between them to form a predetermined laminated structure. It is manufactured by assembling it into a swelling member, putting it in a heating oven and heating it to bond the whole. At this time, depending on the type of adhesive, it may be naturally cooled without being heated.

According to the method of fusing and integrating using a fusible material, for example, a thin sheet-like fusible liquid-conducting material is prepared, and the method of the first embodiment is used. It is manufactured by wrapping the manufactured swelling member 2 and cutting an unnecessary part to form it, and then putting it in a heating oven to heat and fuse the whole. Alternatively, a sheet-shaped swelling material and a liquid-conducting material, at least one of which is fusible, are prepared, and a swelling layer,
After cutting the liquid-conducting layer and the liquid-conducting layer surrounding the laminated body into a predetermined shape for each layer, they are assembled into a swelling member having a predetermined laminated structure and then placed in a heating oven to heat the whole. It is manufactured by fusing.

Next, the third and fourth embodiments of the swelling member will be described.

The swelling member in which the swelling layer and the liquid-conducting layer are multi-layered and integrally formed as in the first embodiment described above can be formed into various shapes according to the structure of the sensor and the like. FIG. 5 is a perspective view of the cylindrical swelling member 22 of the third embodiment, and FIG. 6 is a perspective view of the donut-shaped swelling member 23 of the fourth embodiment. These are suitable for sensors in which the container has a cylindrical shape and the stress applying member has a piston-like structure. Swelling member 22 and swelling member 23
Is manufactured by a method similar to the manufacturing method described in the first embodiment.

Next, a second embodiment of an optical fiber liquid sensor using the swelling member 22 will be described with reference to FIGS. 7 to 9.
An example will be described.

FIG. 7 is a sectional view of the optical fiber liquid sensor before the liquid to be detected has entered, and FIG. 8 is a sectional view of the optical fiber liquid sensor after the liquid to be detected has entered and the swelling member 22 has swollen.
FIG. 9 is an enlarged view of the stress applying member 34 as seen from the axial direction of the optical fiber 7.

As shown in FIG. 7, in the optical fiber liquid sensor, a swelling member 22 is provided in a lower part, a stress applying member 34 is provided above the container 31, and a receiving member 35 is provided further above in a plastic cylindrical container 31. The optical fiber 7 is inserted and assembled so as to be inserted and inserted between the stress applying member 34 and the receiving member 35 through the insertion hole 36 which is housed in the container 31. The swelling member 2 is provided on the side surface of the container 31.
A liquid permeation hole 38 is provided for communicating the place where 2 is arranged with the outside to allow the liquid to enter.

On the optical fiber 7 side of the stress applying member 34,
A pressing portion that bulges in a chevron shape is formed, and the receiving member 35
A concave portion is formed on the side of the optical fiber 7 corresponding to the mountain-shaped pressing portion.

As shown in FIG. 9, the pressing portion of the stress applying member 34 is sandwiched by semi-disc shaped guides on both sides of the semi-disc shaped chevron so that the optical fiber 7 does not come off the chevron shaped portion. Is formed in. When the liquid to be detected enters from the liquid permeation hole 38, the swelling member 22 swells rapidly as shown in FIG. 8 and the stress applying member 34 is moved to the optical fiber 7 side, and as a result, is pressed by the stress applying member 34. The optical fiber 7 is bent into a mountain shape, and the optical fiber liquid sensor operates.

Next, a third embodiment will be described as an embodiment of the optical fiber liquid sensor using the swelling member 23 with reference to FIGS. 10 to 12.

FIG. 10 is a sectional view of the optical fiber liquid sensor before the liquid to be detected has entered, FIG. 11 is a sectional view of the optical fiber liquid sensor after the liquid to be detected has entered and the swelling member 23 has swollen, and FIG. FIG. 6 is an enlarged view of the stress applying member 44 seen from the axial direction of the optical fiber 7.

As shown in FIG. 10, in the optical fiber liquid sensor, the swelling member 23 is provided in the lower part, the stress applying member 44 is provided above the container 41, and the receiving member 45 is provided above the container 41, which is made of plastic. The optical fiber 7 is inserted and assembled so that the optical fiber 7 is accommodated and sandwiched between the stress applying member 44 and the receiving member 45 through the insertion hole 46 that is covered in the container 41. On the bottom surface of the container 41, the swelling member 2
A liquid-permeable hole 48 for allowing a liquid to enter the outside from 3 is provided so as to coincide with the inner hole of the swelling member 23 formed in a donut shape.

A pressing portion that bulges in a mountain shape is formed on the optical fiber 7 side of the stress applying member 44, and a concave portion is formed on the optical fiber 7 side of the receiving member 45 so as to correspond to the mountain-shaped pressing portion. Has been done.

As shown in FIG. 12, the pressing portion of the stress applying member 44 is sandwiched by the semi-disc shaped guides on both sides of the semi-disc shaped chevron so that the optical fiber 7 does not come off the chevron shaped portion. Is formed in. When the liquid to be detected enters from the liquid permeation hole 48, as shown in FIG.
3 swells and the stress applying member 44 is moved to the optical fiber 7 side. As a result, the stress applying member 44 pushes the optical fiber 7 into a mountain shape, and the optical fiber liquid sensor operates. This optical fiber liquid sensor is suitable when liquid cannot enter only from the bottom surface of the optical fiber liquid sensor due to conditions such as the installation location. Depending on the conditions, a liquid permeation hole may be formed on the side surface of the container 41 of the optical fiber liquid sensor.

Similar to the swelling member of the second embodiment shown in FIG. 4, the laminate of the swelling layer of the swelling member 22 or the swelling member 23 and the liquid guiding layer is surrounded by the liquid guiding layer and integrally molded. It is also possible to configure a swelling member having a different structure. By changing the swelling member having this structure to the swelling member 22 or the swelling member 23,
By using the optical fiber liquid sensor shown in FIG. 7 or FIG. 10, the swelling characteristics can be further improved. This swelling member is manufactured by a method similar to the manufacturing method described in the second embodiment.

Next, a fifth embodiment of the swelling member will be described with reference to FIG.

FIG. 13 is an enlarged perspective view showing another structural example of the swelling member used in the optical fiber liquid sensor shown in FIG. As shown in FIG. 13, the swelling member 24 is integrally formed by alternately stacking the swelling layers 24A and the liquid conducting layers 24B in a spiral shape. Such a swelling member is suitable for a sensor in which the container has a cylindrical shape and liquid cannot enter only from the bottom surface of the container.

As for the swelling member 24, the method of bonding and unifying by using an adhesive, the method of unifying by fusion using a fusible material for at least one of the swelling layer and the liquid conducting layer, It is manufactured by a method substantially similar to that of the first embodiment, such as a method of physically fixing and integrally fixing.

For example, according to the method of adhering and integrating using an adhesive, a plate-like or sheet-like swelling material and a liquid-conducting material are prepared, and the whole or a part of the surface serving as a boundary between the two is prepared. Then, after applying the optimum adhesive depending on the material and stacking them on top of each other to form a single layer of composite swelling member,
After applying the adhesive on one side, wrap it in a spiral shape until it reaches the specified cross-sectional size and adhere it closely, put it in a heating oven and heat it to bond and integrate the whole, then cut and mold it to the specified length. Manufactured.

Further, according to the method of fusing and integrating using a fusing material, for example, a swelling material and a liquid-conducting material, which are plate-like or sheet-like and at least one of which has a fusing property, are prepared. Then, they are laminated and adhered to each other to form a single layer of composite swelling member, which is then spirally wound and adhered until it reaches a predetermined cross-sectional size, and then placed in a heating oven and heated to fuse and integrate the whole. It is manufactured by cutting and shaping it into a predetermined length after it is made into a material.

Next, a fourth embodiment will be described as an embodiment of the optical fiber liquid sensor using the swelling member 24, with reference to FIGS. 14 and 15.

FIG. 14 is a sectional view of the optical fiber liquid sensor before the liquid to be detected has entered, and FIG. 15 is a sectional view of the optical fiber liquid sensor after the liquid to be detected has entered and the swelling member has swollen. As shown in FIG. 14, in the optical fiber liquid sensor, a swelling member 53A and a swelling member 53B, which are formed by dividing the swelling member 24 into two parts, are housed inside a thin plastic cylindrical container 51. The stress applying member 54 and the receiving member 55 are housed in the middle of the both swelling members, and are sandwiched between the stress applying member 54 and the receiving member 55 through the insertion hole 56 in the container 51. The optical fiber 7 is inserted and assembled. Container 51
A liquid-permeable hole 48 is formed on the side surface of the device for communicating the location where the swelling member 53A and the swelling member 53B are arranged with the outside and allowing the liquid to enter from the outside. A pressing portion that bulges in a mountain shape is formed on the optical fiber 7 side of the stress applying member 54, and a valley portion is formed on the optical fiber 7 side of the receiving member 55 so as to correspond to the mountain shaped pressing portion. . When the liquid to be detected enters from the liquid-permeable hole 58, as shown in FIG. 15, the swelling member 53A and the swelling member 53B are swollen and the stress applying member 54 and the receiving member 55 are moved to the optical fiber 7 side. The optical fiber 7 is bent into a mountain shape by being pressed by the stress applying member 54 and the receiving member 55, and the optical fiber liquid sensor operates.

Similar to the swelling member of FIG. 4 of the second embodiment described above, the swelling of the structure in which the laminated body of the swelling layer of the swelling member 24 and the liquid conducting layer is surrounded by the liquid conducting layer and integrally molded. The member can also be configured. The swelling member having this structure is used as the swelling member 2
By using the optical fiber liquid sensor shown in FIGS. 14 and 15 in place of No. 4, the swelling property can be further improved. This swelling member is manufactured by a method substantially similar to the manufacturing method described in the second embodiment.

Next, a more specific description will be given with reference to specific examples.

First, six 0.8 mm-thick resin sheets containing a commercially available water-absorbent resin as a main component were prepared as swelling layers,
Water-impregnated paper as a liquid-conducting layer is stacked between the sheets, and the sheets are placed in a heating oven at 60 ° C to 70 ° C.
Heated for 1 hour. The water soaked in the paper was soaked in the swelling layer and heated, so that the swelling layer became fusible and sufficiently fused with the paper between the layers to form a laminate.

This laminate was punched with a 27 mm × 1.7 mm rectangular die to prepare a swelling member 3 for detecting water immersion. The swelling member 3 thus formed did not separate into individual layers, but integrally formed a laminated body.

The swelling member 3 was housed in the container 1 of the optical fiber liquid sensor shown in FIG. 1, and the optical fiber 7 was inserted into the container 1 to assemble the optical fiber water immersion sensor for water immersion detection.

Next, a backscattered light intensity measuring device is connected to one end of the optical fiber 7, the sensor is immersed in water while measuring the loss in the longitudinal direction of the optical fiber 7, and an increase in loss is confirmed from the start of immersion. The response time until it was measured was measured. As a result, the response time was 28 minutes on average (test number of times: 46 times, longest response time: 40 minutes, shortest response time: 13 minutes).

On the other hand, an optical fiber submersion sensor was constructed by accommodating in a container 1 a swelling member formed by simply stacking six resin sheets punched into a rectangular shape without sandwiching paper as a liquid conducting layer. . This optical fiber immersion sensor was tested under the same conditions, and the response time was measured. As a result, the response time was 50 minutes or more.

Next, another specific example will be described.

First, six 0.8 mm-thick resin sheets containing a commercially available water-absorbent resin as a main component were prepared as swelling layers,
Prepare 5 sheets of paper as the liquid-conducting layer, stack them alternately while applying a thin glue solution on top of the layers between layers, and put them in a constant temperature bath.
A laminate was prepared by heating at 0 ° C to 70 ° C for 1 hour.

This laminated body was punched with a rectangular die of 27 mm × 1.7 mm to produce a swelling member 3 for detecting water immersion. The swelling member 3 thus completed did not separate into individual layers and was integrated into a laminated body.

The swelling member 3 was housed in the container 1 of the optical fiber liquid sensor shown in FIG. 1, and the optical fiber 7 was inserted into the container 1 to assemble an optical fiber water immersion sensor for detecting water immersion.

Next, a backscattered light intensity measuring device is connected to one end of the optical fiber 7, the loss in the longitudinal direction of the optical fiber 7 is measured, and the sensor is immersed in water. The response time up to the measurement was measured. As a result, the response time was 30 minutes on average (test number of times: 46 times, longest response time: 50 minutes, shortest response time: 14 minutes).

As a result of these tests, it was confirmed that the optical fiber water immersion sensor of the present invention has extremely good responsiveness.

[0081]

As described above, in the optical fiber liquid sensor of the present invention, the swelling member is divided into a plurality of swelling layers,
Moreover, since the liquid-conducting layer formed of the liquid-conducting material that conducts the liquid to be detected is interposed between the layers of the respective divided layers, the liquid is guided to the liquid-conducting layer between the layers and quickly between the swelling layers. Penetrate into.

Further, the surface area is expanded by the layer division and the entire surface is rapidly immersed in the liquid by the liquid guiding layer. As a result, each swelling layer is thinner than the surface area, so that the liquid swells. The layers are quickly absorbed and the individual swelling layers swell almost simultaneously. Therefore, the entire swelling member can be immediately expanded from the liquid immersion.

Further, since the liquid conducting layer is interposed between the layers of the respective swelling layers, the respective layers of the swelling layers are in close contact with each other and the layers of the swelling layers are closed, and the liquid absorption rate is not lowered. Therefore, according to the optical fiber liquid sensor of the present invention, the swelling member has a high swelling speed, and the liquid to be detected can be instantly detected.

Furthermore, since the swelling layer is densely and integrally formed via the liquid conducting layer, all the swelling of the swelling layer appears as the expansion of the entire swelling member, and the optical fiber is bent strongly. Provides a clear loss increase. Further, since the swelling member is integrally molded, it can be easily processed into a predetermined shape, and the workability of assembling the sensor into the container is good, improving the productivity and improving the manufacturing cost. To be done.
In addition, the shape of the swelling member is stable, and as a result, the expansion upon flooding is also stable, the loss increase characteristic of the optical fiber is stable, and the reliability of the sensor can be improved.

[Brief description of drawings]

FIG. 1 is a sectional view of a first embodiment of an optical fiber liquid sensor according to the present invention before swelling.

2 is a cross-sectional view of the optical fiber liquid sensor shown in FIG. 1 after swelling.

FIG. 3 is an enlarged cross-sectional view showing the structure of the first embodiment of the swelling member according to the present invention.

FIG. 4 is an enlarged cross-sectional view showing the configuration of a second embodiment of the swelling member according to the present invention.

FIG. 5 is an enlarged perspective view showing the configuration of a third embodiment of the swelling member according to the present invention.

FIG. 6 is an enlarged perspective view showing the configuration of a fourth embodiment of the swelling member according to the present invention.

FIG. 7 is a sectional view of a second embodiment of the optical fiber liquid sensor according to the present invention before swelling.

8 is a cross-sectional view of the optical fiber liquid sensor shown in FIG. 7 after swelling.

9 is an enlarged view of the stress applying member of the optical fiber liquid sensor shown in FIG. 7, as viewed in the axial direction of the optical fiber.

FIG. 10 is a sectional view of a third embodiment of an optical fiber liquid sensor according to the present invention before swelling.

11 is a cross-sectional view of the optical fiber liquid sensor shown in FIG. 10 after swelling.

FIG. 12 is an enlarged view of the stress applying member of the optical fiber liquid sensor shown in FIG. 10 as seen from the axial direction of the optical fiber.

FIG. 13 is an enlarged perspective view showing the structure of a swelling member according to a fifth embodiment of the present invention.

FIG. 14 is a cross-sectional view of an optical fiber liquid sensor according to a fourth embodiment of the present invention before being swollen.

15 is a sectional view of the optical fiber liquid sensor shown in FIG. 14 after the swelling member has swollen.

FIG. 16 is a flowchart showing a procedure for producing a swelling member according to the present invention.

FIG. 17 is a flowchart showing another procedure for producing the swelling member according to the present invention.

[Explanation of symbols]

1, 31, 41, 51 Container 2 Guide member 3, 21, 22, 23, 24, 53A, 53B Swelling member 3A, 24A Swelling layer 3B, 21B, 24B Liquid transfer layer 4, 34, 44, 54 Stress applying member 5 , 35, 45, 55 Receiving member 6, 36, 46 Optical fiber insertion hole 7 Optical fiber 8, 38, 48, 58 Liquid permeation hole

Claims (4)

[Claims] 1. An optical fiber liquid sensor for detecting the presence of a liquid to be detected by deforming an optical fiber due to swelling of a swelling member by the liquid to be detected, and increasing the transmission loss of the optical fiber, wherein the swelling member is A swelling layer that swells with the liquid to be detected and a liquid-conducting layer that conducts the liquid to be detected are alternately laminated, and all layers are integrated by bonding, fusing or fixing the layers. An optical fiber liquid sensor characterized in that it is constructed. 2. A laminate in which a plurality of swelling layers and a liquid-conducting layer are alternately laminated, and all layers are integrally formed by bonding, fusing or fixing each layer. A swelling member for an optical fiber liquid sensor, characterized in that the body is molded into a predetermined shape. 3. A swelling layer and a liquid-conducting layer are concentrically or spirally laminated, and all layers are integrated by bonding, fusing or fixing each layer. A swelling member formed by molding a laminate into a predetermined shape. 4. A layered body formed by laminating a swelling layer and a liquid-conducting layer is surrounded by a liquid-conducting layer and adhered, fused or fixed to the laminated body so that all layers are integrated. The swelling member according to claim 2 or 3, wherein the swelling member is configured as described above.