JP2543344B2 - Leak sensor - Google Patents

Description

TECHNICAL FIELD The present invention relates to a leak sensor for detecting a liquid leaking from a joint portion of adjacent pipes.

[Prior Art] For example, in a pipe that conveys water or an aqueous solution, a pair of electrodes has been provided in the vicinity of the pipe in order to detect liquid leakage. In this case, a predetermined voltage is always applied between the pair of electrodes so that the electrodes are short-circuited.
When leaked water or aqueous solution adheres, a predetermined electric current flows to detect the leak.
Such an electrode is usually provided in association with a joint portion of a pipe where liquid leakage is likely to occur.

[Problems to be Solved by the Invention] In the above-described conventional water leak detection method, there is a problem in safety because the electrodes must be exposed to the outside air while a voltage is always applied. Further, if an expensive noble metal is not used as a material for the electrodes, the electrodes may be rusted or corroded over time. For this reason, the ability to detect liquid leakage may decrease over time. In addition, it has not been so easy to introduce leaked water or an aqueous solution between a pair of electrodes and reliably short-circuit the electrodes with such a liquid. For example, when the liquid leakage is very small, the pair of electrodes cannot be short-circuited and the liquid leakage may be overlooked for a long time.

Therefore, the present invention is intended to provide a liquid leakage sensor capable of solving the above-mentioned conventional problems.

[Means for Solving Problems] The present invention is premised on a leak sensor for detecting a liquid leaking from a joint portion between adjacent pipes. The liquid leakage sensor is connected to a pipe and extends downward, a container attached to a lower portion of the holder for receiving a liquid leaking and falling from a joint portion of the pipe, and a storage space of the container. , An absorber that expands in volume by absorbing liquid. The container has a wall portion that allows liquid to pass therethrough and an opening that allows the absorbent body to swell at the bottom portion. The liquid leakage sensor is further stretched along the opening of the container and expands in accordance with the volume expansion of the absorber, and a detection unit for detecting displacement of the diaphragm due to expansion of the diaphragm. It has and.

[Operation] When such a leak sensor detects a liquid leaking from the joint portion of the adjacent pipe, it works as follows. That is, the liquid leaking from the pipe joint portion drops downward and enters the container through the wall portion that allows the passage of the liquid. Here, the absorber absorbs this liquid and expands itself in volume. The volume expansion of the absorbent body defines a certain inner volume of the container, so the absorbent body swells from the opening of the container. Since the stretchable diaphragm is stretched along the opening of the container, it expands in accordance with the volume expansion of the absorbent body. The displacement of the diaphragm due to the bulging of the diaphragm is detected by the detection means.

[Effects of the Invention] As described above, according to the present invention, the presence of the liquid leaking from the pipe joint portion can be reliably detected with a relatively simple configuration. That is, by arranging the container on the path through which the liquid leaks, all the liquid generated by the liquid leak can be absorbed by the absorber. Therefore, even if a small amount of leaked liquid is accumulated, the absorber surely expands, so that a highly reliable detection operation can be obtained.

In addition, since it is not necessary to provide a detection means in a state of directly contacting the liquid to be detected or directly exposed to the outside air, there is no problem of lack of safety as in the case of the above-mentioned conventional technique, Further, there is no problem of rust or corrosion. In particular, the latter advantage also means that a reliable detection operation is always achieved.

Further, since the leaked liquid continues to be absorbed until the absorber becomes saturated, it is possible to prevent the leaked liquid from polluting the periphery of the pipe. Further, since the liquid once absorbed by the absorber rarely leaks from the container due to factors such as external vibrations, it can be used as a leak sensor for piping in vehicles such as ships and airplanes. Even so, as described above, it is almost prevented that the circumference of the pipe is soiled.

Further, when returning the leak sensor that has once detected the liquid, it is only necessary to replace the absorber with a new one, and maintenance is easy.

[Embodiment] FIG. 1 is a sectional view taken along the line I-I in FIG. 2, but the liquid leakage sensor according to the present invention is used as a liquid leakage sensor as shown in FIG. It is shown as applied to the joint portion 3 of the book pipe 1,2. In addition, in this embodiment, the liquid to be detected is water or an aqueous solution (hereinafter collectively referred to as “water”), and in the pipes including the pipes 1 and 2,
As shown in FIG. 1, water 4 is circulating.

FIG. 1 shows a liquid leakage sensor 5 according to an embodiment of the present invention mainly in a sectional view. In order to hold the liquid leakage sensor 5 as described above, a frame extending downward from the pipes 1 and 2 is provided. A holder 6 to be formed is provided. A container 7 is formed at the lower end of the holder 6. The container 7 is made of a relatively rigid material such as metal or plastic.

In FIG. 1, the water 4a leaked from the joint portion 3 is shown, but the wall 8 of the container 7 for receiving such water 4a is shown.
Is made of, for example, a hydrophilic porous plastic plate so as to allow the passage of water 4a. An opening 9 is formed on the lower surface of the container 7, and an extensible diaphragm 10 is stretched along the opening 9. Stretchable diaphragm 10
Is preferably composed of a material that does not allow the passage of liquids, for example a resilient material such as a thin rubber sheet is selected. In addition, such a diaphragm 10 is
It does not necessarily need to have elasticity, but it is sufficient if it has mere extensibility, that is, the property of being easily extended by a force applied from the outside, and when such a force is removed, the original state is obtained. There is no need to return to.

Inside the container 7 is an absorber 11 that absorbs the water 4a and expands in volume.
Is filled. The absorber 11 contains a water-absorbent resin such as a grafted starch-based resin or a vinyl acrylate copolymer, and such a resin is used in a powder or granular form in order to increase its water absorption rate. In FIG. 3, the preferable composition of the absorber 11 is enlarged and illustrated. In FIG. 3, what is indicated by a circle is a powdery or granular water-absorbent resin 12, and such a resin 12 is used by being mixed with an aggregate of fibers 13 shown in a linear shape. As the aggregate of the fibers 13, for example, commercially available absorbent cotton can be advantageously used. Also, water absorbent resin
As 12, it was confirmed that “Sumikagel S-50” (trade name of spherical particles of vinyl acrylate vinyl alcohol copolymer manufactured by Sumitomo Chemical Co., Ltd.) can be advantageously used.

The reason why the fibers 13 are mixed with the powder or particles of the water absorbent resin 12 as described above is as follows. That is, when a part of the absorbent body 11 absorbs the water 4a and the water absorbent resin 12 expands in volume, the water absorbent resin around the water absorbent resin 12 is present.
The packing density of the 12 powders or particles is increased, which may impede the permeation of the water 4a between the surrounding water absorbent resins 12. The fiber 13 ensures the formation of a gap that allows passage of the water 4a between the powder or particles of the water-absorbent resin 12, and functions to alleviate the occurrence of the so-called water-stopping phenomenon as described above.

Referring again to FIG. 1, below the diaphragm 10,
A micro switch 14 as a detection means is arranged. The actuator 15 of the micro switch 14 is a diaphragm
It projects toward 10, and is configured such that when the diaphragm 10 bulges as shown by an imaginary line, the actuator 15 is pushed by the diaphragm 10 itself.

The liquid leakage sensor 5 configured as described above has the joint portion 3
The water 4a leaking from the water is detected as follows. First, the water 4a
It falls on the wall 8. Since the wall portion 8 is permeable to water, this water 4a is absorbed by the absorber 11. The absorber 11 is
Absorption of water 4a causes volume expansion, and this volume expansion is
It causes the bulging of the extensible diaphragm 10. Then, when the diaphragm 10 swells as shown by an imaginary line in FIG. 1, the actuator 15 of the micro switch 14 is pushed in. As a result, the microswitch 14 is turned on, and in response thereto, a signal is derived from the microswitch 14.

4 to 6 each show another example of the detecting means which replaces the microswitch 14 described above. In FIGS. 4 to 6, parts corresponding to the parts shown in FIG. 1 are designated by the same reference numerals, and overlapping description will be omitted.

In FIG. 4, the magnet 16 is attached to the lower surface of the diaphragm 10.
Is fixed. Then, in order to detect the displacement of the magnet 16, a reed switch 17 is provided close to the magnet 16.

According to the configuration of FIG. 4, when the diaphragm 10 is kept in a planar state, the reed switch 17 is in the off state, for example, and when the magnet 16 approaches the reed switch 17 as a result of the diaphragm 10 swelling, The reed switch 17 is turned on. Therefore, in response to the water to be detected being absorbed by the absorber 11, the on / off state of the reed switch 17 is switched, and water can be detected.

In the embodiment shown in FIG. 5, the light emitting element 18 and the light receiving element 19 are used. Light from the light emitting element 18 is incident on the lower surface of the diaphragm 10, and when the diaphragm 10 is in a flat state,
The reflected light is received by the light receiving element 19. It should be noted that a portion of the lower surface of the diaphragm 10 that receives light from the light emitting element 18 may be attached with another reflective film or the like in order to increase the reflectance of light.

According to the configuration shown in FIG. 5, when the absorber 11 absorbs water to cause volume expansion and the diaphragm 10 swells as shown by an imaginary line, the reflected light from the light emitting element 18 is: It does not reach the light receiving element 19. Therefore, the light receiving element
The presence of water can be detected by whether or not 19 receives light.

In the embodiment shown in FIG. 6, below the diaphragm 10,
The light emitting element 20 and the light receiving element 21 are arranged to face each other. Further, a shielding plate 22 protruding downward is held on the lower surface of the diaphragm 10.

In the configuration of FIG. 6 as described above, when the diaphragm 10 is in a flat state, the shield plate 22 changes from the light emitting element 20 to the light receiving element.
It is not located on the light path to 21. Then, the absorber 11 absorbs water, and as shown by an imaginary line, the diaphragm
When 10 swells, the shield plate 22 blocks the light path from the light emitting element 20 to the light receiving element 21. Therefore, the light receiving element 22 does not receive light, and thus the presence of water can be detected depending on whether or not the light receiving element 21 receives light.

FIG. 7 shows still another embodiment of the present invention and corresponds to FIG. 1 described above. Note that, in FIG. 7, parts corresponding to the parts shown in FIG. 1 are denoted by the same reference numerals, and overlapping description will be omitted.

In FIG. 7, the leak sensor 5a is arranged such that the orientation of the container 7 is different and the wall portion 8 and the stretchable diaphragm 10 that allow passage of water extend in the vertical direction. Therefore, the microswitch 14 has its actuator 15
Are provided so as to be displaced in the lateral direction. In addition, in order to guide the water 4a to the absorber 11 through the wall portion 8, the temporary storage portion
23 is formed in front of the wall 8.

In the embodiment shown in FIG. 7, the water 4a moves laterally in the absorber 11
Except for entering the inside, the other operations and operations are substantially the same as the embodiment shown in FIG.

Although the present invention has been described above with reference to some illustrated embodiments, various other embodiments are possible within the scope of the present invention.

For example, a wall that allows the passage of liquid is
It may be replaced by a relatively rigid plate such as punched metal or mesh. In this case, in order to prevent the powder or particles of the absorbent resin from escaping, a porous sheet such as paper may be arranged along a plate such as punch metal.

When the absorbent body contains powdery or particulate absorbent resin, the absorbent body may be wrapped with a porous sheet such as paper or cloth before use. This has the advantage that the work of exchanging the absorber becomes easier.

Further, the present invention is not limited to detection of water or aqueous solution,
It can also be applied to the detection of other liquids by selecting the material forming the absorber.

Further, in the illustrated embodiment, the wall portion 8 which allows passage of the liquid and the extensible diaphragm 10 are constituted by separate members, but for example, a material which allows passage of the liquid is used as the material constituting the extensible diaphragm. For example, the liquid to be detected may pass through the diaphragm, and the same diaphragm may swell when the absorber absorbs the liquid and expands.

Further, the detection means for detecting the displacement of the extensible diaphragm may be arranged so as to be able to detect the displacement due to the bulging of the extensible diaphragm, and is therefore not limited to the illustrated arrangement.

[Brief description of drawings]

FIG. 1 is a sectional view taken along line I-I of FIG. 2 showing a case where a leak sensor 5 as an embodiment of the present invention is used to detect a leak from a joint portion 3 of a pipe. It is a figure.
FIG. 2 is a top view of the pipe shown in FIG. FIG. 3 is an enlarged view showing a preferable composition example of the absorber 11. FIG. 4, FIG. 5 and FIG. 6 are schematic diagrams showing other examples of the detecting means. FIG. 7 shows still another embodiment of the present invention and is a view corresponding to FIG. In the figure, 4a is leaked water (liquid), 5 and 5a are leak sensors, 7 is a container, 8 is a wall that allows passage of liquid, 9 is an opening, 10 is an extensible diaphragm, 11 is an absorber, 12 is absorbent resin, 13 is fiber, 14 is micro switch, 15 is actuator, 16 is magnet, 17 is reed switch 1, 18, 2
Reference numeral 0 is a light emitting element, 19 and 21 are light receiving elements, and 22 is a shielding plate.

Claims (16)

(57) [Claims] 1. A leak sensor for detecting a liquid leaking from a joint portion of adjacent pipes, comprising: a holder connected to the pipe and extending downward; and a joint of pipes attached to a lower portion of the holder. The container is provided with a container that receives the liquid that leaks and falls from the portion, and an absorber that is filled in the storage space of the container and that expands in volume by absorbing the liquid. The container allows the passage of the liquid in the upper portion. An extensibility that has a wall portion, has an opening that allows the absorbent body to swell in the bottom portion, is stretched along the opening of the container, and expands in accordance with the volume expansion of the absorbent body. A leak sensor, comprising: a diaphragm; and a detection unit that detects displacement of the diaphragm due to bulging of the diaphragm. 2. The leak sensor according to claim 1, wherein the liquid is water or an aqueous solution. 3. The leak sensor according to claim 2, wherein the absorber contains a water absorbent resin. 4. The leak sensor according to claim 3, wherein the water-absorbent resin is a grafted starch-based resin or a vinyl acrylate alcohol copolymer. 5. The liquid leakage sensor according to claim 1, wherein the absorber contains powdery or granular resin. 6. The liquid leakage sensor according to claim 5, wherein the powdery or granular resin is mixed with the fiber assembly. 7. The wall portion which allows the passage of the liquid is composed of a porous plastic plate.
Item or the liquid leakage sensor according to item 6. 8. The wall portion which allows the passage of the liquid is constituted by a rigid plate having a plurality of penetration paths and a porous sheet arranged along the plate, The liquid leakage sensor according to item 5 or 6. 9. The liquid leakage sensor according to claim 1, wherein the diaphragm is made of a material that does not allow liquid to pass therethrough. 10. The leak sensor according to claim 1, wherein the diaphragm is made of an elastic material. 11. The leak sensor according to claim 10, wherein the diaphragm is made of a rubber sheet. 12. The leakage according to any one of claims 1 to 11, wherein the detection means includes a microswitch having an actuator which is pressed by the diaphragm itself according to the displacement of the diaphragm. Liquid sensor. 13. The method according to claim 1, wherein the detection means includes a combination of a magnet fixed to the diaphragm and a reed switch that detects displacement of the magnet. The leak sensor described. 14. The liquid leakage sensor according to claim 1, wherein the detecting means includes an optical detecting device including a combination of a light emitting element and a light receiving element. 15. The optical detection device comprises a light emitting element for making light incident on the surface of the diaphragm, and a light receiving element for receiving reflected light from the surface of the diaphragm, and the reflection element is provided according to the displacement of the diaphragm. 15. The liquid leakage sensor according to claim 14, wherein a state where light reaches the light receiving element and a state where light does not reach the light receiving element are created. 16. The optical detection device comprises a light emitting element, a light receiving element for receiving light from the light emitting element, and a shield plate held by the diaphragm and moving in and out of the path of the light according to the displacement of the diaphragm. Claims comprising
The leak sensor according to item 14.