JP2016102771A - Liquid leakage sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid leakage sensor that can be installed in a narrow gap and can detect a little liquid leakage.SOLUTION: A liquid leakage sensor 1A detects liquid 40 by a change in refractive index that is detected by a sensor part 3 formed by a bent part of an optical fiber contacting the liquid. The liquid leakage sensor 1A has a holder 10 that holds the sensor part 3, and liquid collection means 20 that collects the liquid 40 to be detected to wet the sensor part 3 (liquid absorptive sheet 21 and liquid guide groove 18).SELECTED DRAWING: Figure 2

Description

  The present invention relates to a liquid leakage sensor that detects a liquid by detecting a change in the refractive index of a medium using an optical fiber.

  As a leak sensor for detecting leaks of water-based liquids such as water, acidic solutions, and alkaline solutions, and oil-based liquids such as alcohol, thinner, and gasoline, the thin paper absorbs the liquid and the transmittance or reflectance of the thin paper changes. A liquid leakage sensor utilizing this is known (Patent Document 1). In this liquid leakage sensor, when light is projected and received on a thin paper using an optical fiber, the liquid leakage can be detected safely even for a flammable or explosive liquid.

  However, in this water leakage sensor, a light projecting portion and a light receiving portion are provided in the holder, and the bottom area and height of the holder are increased in order to observe the reflected light or transmitted light transmitted through the thin paper, and the water leakage sensor is narrow. It cannot be installed in the gap. In fact, the holder of this type of practical machine has a bottom diameter of 30 mm or more and a height of 14 mm or more.

On the other hand, there is known a liquid sensor that detects a liquid from a change in refractive index detected when an optical fiber core is exposed and the curved portion comes into contact with liquid, or measures a liquid composition. (Patent Document 2).
However, this liquid sensor cannot be used for detecting a small amount of liquid leakage because the curved portion of the optical fiber must be put in the liquid.

JP 2000-180294 A JP-A-2-236146

  The subject of this invention with respect to the above-mentioned prior art is providing the leak sensor which can be installed also in a narrow gap | interval and can detect a slight leak.

  The present inventor detects a liquid by detecting a change in refractive index with a curved portion of an optical fiber, and protects the curved portion of the optical fiber serving as the detection portion with a holder, and a liquid collecting means on the holder. In addition, the inventors have found that the above-described problems can be solved by bringing the detection unit into contact with the liquid collected by the liquid collecting means, and have arrived at the present invention.

  That is, the present invention is a liquid leakage sensor that detects a liquid by a change in refractive index detected by contact of a sensor portion formed by a curved portion of an optical fiber, and a holder that holds the sensor portion, Provided is a liquid leakage sensor having liquid collecting means for collecting liquid to be wetted to wet a sensor unit.

  According to the liquid leakage sensor of the present invention, the liquid collecting means included in the holder collects the liquid on the liquid detection target surface, and the liquid on the liquid detection target surface is detected by the sensor unit getting wet with the liquid. Accordingly, even a small amount of liquid can be detected by thinly spreading the liquid collecting means on the liquid detection target surface.

  In addition, a liquid-absorbing sheet or the like can be used as the liquid collecting means, and the liquid is detected by detecting a change in the refractive index with an optical fiber, so that the liquid collecting means and the sensor section are both thin and compact. Can be formed. Therefore, it is possible to attach a leak sensor to a narrow gap. Further, since the liquid is detected by the optical fiber, it is possible to meet the explosion-proof request when the liquid to be detected is an organic solvent or the like.

FIG. 1A is a component diagram of a liquid leakage sensor 1A of the embodiment. FIG. 1B is a top view of the liquid leakage sensor 1A of the embodiment. FIG. 2 is a sectional view of the liquid leakage sensor 1A according to the embodiment in use. FIG. 3A is a component diagram of the liquid leakage sensor 1B of the embodiment. FIG. 3B is a top view of the liquid leakage sensor 1B of the embodiment. FIG. 4 is a sectional view of the leakage sensor 1B of the embodiment in use. FIG. 5A is a component diagram of the liquid leakage sensor 1C of the embodiment. FIG. 5B is a top view of the liquid leakage sensor 1C of the embodiment. FIG. 6A is a cross-sectional view of the liquid leakage sensor 1C of the embodiment in use. FIG. 6B is a cross-sectional view of the liquid leakage sensor 1C according to the embodiment in use. FIG. 7 is a top view of the liquid leakage sensor 1D of the embodiment. FIG. 8 is a top view of the leak sensor 1E of the embodiment. FIG. 9 is a top view of the liquid leakage sensor 1F according to the embodiment. FIG. 10 is a top view of a usage mode of the liquid leakage sensor 1D of the embodiment. FIG. 11 is a cross-sectional view of the leakage sensor 1D of the embodiment in use. FIG. 12A is a top view of the liquid leakage sensor 1G of the embodiment. FIG. 12B is a side view of the liquid leakage sensor 1G of the embodiment. FIG. 13 is a cross-sectional view of the leakage sensor 1G of the embodiment in use.

  Hereinafter, the present invention will be specifically described with reference to the drawings. In each figure, the same numerals indicate the same or equivalent components.

  1A is a component diagram of a leak sensor 1A according to an embodiment of the present invention, FIG. 1B is a top view of the leak sensor 1A formed from the components shown in FIG. 1A, and FIG. It is sectional drawing of a state.

  In this liquid leak sensor 1A, a curved portion where the core of the optical fiber 2 composed of a core and a clad is exposed and curved is defined as a sensor portion 3, and a change in refractive index detected by the sensor portion 3 coming into contact with liquid is detected. To detect the presence of liquid.

  As the sensor part 3, the sensor part of the leak sensor which consists of the curved part of the well-known optical fiber described in patent document 2 grade | etc., Can be used.

  The sensor unit 3 is held by a holder 10 that protects the sensor unit 3 from external force. More specifically, in this embodiment, the sensor unit 3 is attached to the fixing member 4 in order to maintain the curved shape. The holder 10 has a substantially annular outer shape, a notch 11 is formed on the peripheral wall, and a step 12 is formed on one opening edge. Then, the fixing member 4 of the sensor unit 3 is fixed by being fitted into the notch 11 of the holder 10.

  Although there is no limitation in particular in the shape and magnitude | size of a holder in this invention, the holder 10 of a present Example can be made into 10-50 mm in external shape and 2-10 mm in thickness, for example.

  A liquid absorbent sheet 21 is detachably attached to the holder 10 as a liquid collecting means 20 that collects the liquid to be detected and wets the sensor unit 3.

  As a material for forming the liquid-absorbent sheet 21, a thin paper, a nonwoven fabric, a woven fabric, a resin sheet having continuous foaming, etc. having liquid absorption, liquid retention or leaching action can be used. For example, the (registered trademark) “Bencot” series manufactured by Asahi Kasei Fibers Corporation can be used.

  The liquid-absorbent sheet 21 has a circular outer shape that is fitted in the step portion 12 of the holder 10, and a tongue-shaped floating portion 23 is formed in the center portion by the notch 22. The thickness of the liquid absorbent sheet 21 can be set to 0.2 to 2 mm, for example.

  As shown in FIGS. 1B and 2, when the sensor unit 3 and the liquid absorbent sheet 21 are attached to the holder 10, the liquid absorbent sheet 21 is in contact with the liquid detection target surface 30. The sensor part 3 is sandwiched between the liquid detection target surface 30 and the raised part 23 of the liquid absorbent sheet 21.

  As a method of using the liquid leakage sensor 1A, the liquid leakage sensor 1A assembled in this way is placed on the liquid detection target surface 30. When the liquid 40 is present on the liquid detection target surface 30, the liquid 40 is absorbed by the liquid absorbent sheet 21, penetrates as shown by arrows in FIG. 2 due to capillary action, and the lifted portion of the liquid absorbent sheet 21. 23, the sensor unit 3 is wetted. Thereby, the liquid 40 can be detected. In particular, when the amount of liquid absorbed by the liquid absorbent sheet 21 is sufficient, the droplet 41 is accumulated between the liquid detection target surface 30 and the floating portion 23, and the sensor unit 3 is inserted into the droplet 41. It becomes a state. Thereby, the liquid 40 can be detected more reliably.

  The liquid absorbent sheet 21 that has once absorbed the liquid 40 is replaced with a new liquid absorbent sheet 21.

The present invention can take various aspects.
For example, as shown in FIGS. 3A and 3B, the pressing member 13 of the liquid absorbent sheet 21 may be combined with the above-described liquid leakage sensor 1 </ b> A. The pressing member 13 has a convex portion 14 at the center, and is detachably fixed to the outer periphery of the holder 10 by the spring property of the protruding piece 15 protruding from the outer peripheral portion.

  As shown in FIG. 4, in the usage state of the liquid leakage sensor 1 </ b> B, the center portion of the pressing member 13 is located between the liquid detection target surface 30 and the liquid absorbent sheet 21, and the raised portion of the liquid absorbent sheet 21. 23 is pushed up. Accordingly, it is preferable that the liquid absorbent sheet 21 absorbs liquid because the droplets 41 are easily collected in the floating portion 23.

  In this invention, there is no restriction | limiting in particular in the shape of the holder 10 or the liquid absorbing sheet 21, and there is also no restriction | limiting also in the attachment method of the liquid absorbing sheet 21 in the holder 10. FIG. For example, in the leak sensor 1C shown in FIGS. 5A and 5B, the optical fiber 2 in the vicinity of the sensor unit 3 is embedded in the holder 10 so that the sensor unit 3 is positioned in the recess 16 formed at the end of the holder 10. The holder 10 has a function of fixing the curved shape of the sensor unit 3 and a function of protecting the sensor unit 3 from an external force.

  Further, in this liquid leakage sensor 1C, a raised portion 23 is formed by projecting a tongue-like portion at one end of the liquid absorbent sheet 21, and in the usage state of the liquid leakage sensor 1C, as shown in FIG. 5B. The raised portion 23 of the liquid absorbent sheet 21 is inserted into the concave portion 16 of the holder 10. For this reason, the entire shape of the liquid-absorbent sheet 21 can be arbitrarily expanded outside the holder 10 depending on the purpose of the leak detection, the installation location of the leak sensor, etc., regardless of the shape and size of the holder 10. . For example, the entire shape of the liquid-absorbent sheet 21 may be circular like the liquid leakage sensor 1D shown in FIG. 7, or may be rectangular like the liquid leakage sensor 1E shown in FIG. 8, and the leakage shown in FIG. You may make it cyclic like the liquid sensor 1F.

  Further, the holder 10 of the liquid leakage sensor 1C is provided with a through-hole 17 through which a fixing member such as a screw, a bolt, or a hook is passed so that the holder 10 can be fixed to the liquid detection target surface as necessary. Yes. Therefore, for example, as shown in FIG. 6A, the holder 10 may be fixed by the fixing member 18 so that the liquid-absorbent sheet 21 and the grounding surface of the holder 10 are along the horizontal liquid detection target surface 30. As shown in FIG. 6B, the liquid-absorbent sheet 21 runs along the horizontal liquid detection target surface 30, but the holder 10 is fixed so that the grounding surface of the holder 10 follows the vertical wall surface 31. Good.

  As described above, according to the liquid leakage sensor of the present invention, the installation location and the installation direction of the liquid leakage sensor can be arbitrarily determined as long as the liquid can be absorbed by the liquid absorbent sheet.

  Further, in the usage mode of the liquid leakage sensor of the present invention provided with the liquid absorbent sheet, as shown in FIG. 10, the floating portion 23 of the liquid absorbent sheet 21 of the liquid leakage sensor 1D is folded back so that the sensor section 3 can absorb the liquid. The sheet may be sandwiched between the raised portion 23 and the main body portion 24 of the adhesive sheet 21. From the point of sensitivity of liquid leakage detection, it is preferable to sandwich the sensor unit between the liquid absorbent sheet and the detection target surface.

  Further, in the present invention, the liquid absorbent sheet 21 may be omitted, and the liquid collecting means 20 may be formed on the holder 10 itself. For example, like the liquid leakage sensor 1G shown in FIGS. 12A and 12B, the liquid introduction groove 19 may be formed as the liquid collecting means 20 on the ground contact surface of the holder 10 with respect to the liquid detection target surface. In the liquid leakage sensor 1G, the liquid introduction grooves 19 are formed radially so that the liquid is guided from the outer peripheral portion of the holder 10 toward the sensor portion 3 attached to the concave portion 16.

1A, 1B, 1C, 1D, 1E, 1F, 1G Leak sensor 2 Optical fiber 3 Sensor part 4 Fixing member 10 Holder 11 Notch part 12 Step part 13 Holding member 14 Protruding part 15 Protruding piece 16 Recessing part 17 Through hole 18 Fixing Member 19 Liquid introducing groove 20 Liquid collecting means 21 Absorbent sheet 22 Notch 23 Lifting portion 24 Main body portion 30 Liquid detection target surface 31 Vertical wall surface 40 Liquid 41 Liquid droplet

Claims (5)

  A liquid leakage sensor that detects a liquid by a change in refractive index detected by contact of a sensor formed by a curved portion of an optical fiber with a holder, a holder that holds the sensor, and a liquid to be detected And a liquid leakage sensor having liquid collecting means for wetting the sensor unit.   The liquid collecting means is formed of a liquid-absorbent sheet, and the liquid-absorbent sheet is attached so that the liquid detection target surface is in contact with the liquid detection target surface and the sensor portion is sandwiched between the liquid detection target surface and the liquid-absorbent sheet. Item 1. The liquid leakage sensor according to item 1.   The liquid leakage sensor according to claim 2, wherein the liquid absorbent sheet is spread out of the holder.   The liquid leakage sensor according to claim 2, wherein the liquid absorbing sheet is held in the holder.   The liquid leakage sensor according to claim 1, wherein a sensor unit is attached to a concave portion of a grounding surface of the holder that is in contact with a liquid detection target surface, and a liquid introduction groove that guides the liquid to the sensor unit is formed on the grounding surface.

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