JPH068768B2 - Infiltration detection sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a water immersion detection sensor using an optical transmission line.

(Prior Art) As a typical conventional water immersion detection sensor, there is a water immersion detection sensor that is composed of two perforated coated copper wires in which a hole is provided in a part of a copper coating and the copper is exposed. This is a sensor that electrically measures a decrease in insulation resistance between two copper wires that occurs during water immersion to detect water immersion. However, since this sensor uses a conductor called a copper wire, it may be affected by electromagnetic induction in a place where a large current or high voltage is generated, and it may be difficult to accurately measure the water immersion point due to fluctuations in the induced current or voltage. It was Further, even when the humidity is high, the insulation resistance between the copper wires is lowered, and there is a disadvantage that the malfunction is detected by detecting as if there was water infiltration. Further, there is a drawback that high sensitivity cannot be achieved in order to prevent the malfunction due to the humidity.

(Problems to be Solved by the Invention) A high-sensitivity inundation detection sensor that is not affected by electromagnetic induction is provided by combining an optical transmission line and a fiber that contracts in contact with water (hereinafter referred to as contraction thread). To do.

(Means for Solving Problems) The present invention detects a water infiltration by giving a local bend to an optical transmission line by a shrinking yarn and measuring an increase in transmission loss due to the local bending.

(Embodiment) FIG. 7 is a plan view of an embodiment of the present invention, showing a state before flooding. In FIG. 7, 1 is a shrink yarn, 2 is an optical transmission line, 8 is a spacer for holding the optical transmission line and giving a local bend to the optical transmission line, 4 is an optical transmission caused by the shrinking action of the shrink yarn at the time of flooding. It is a holding plate for preventing the wire from twisting.

FIG. 8 is a schematic view when the spacer 8 and the holding plate 4 are combined. When this water immersion sensor is flooded, the contraction yarn contracts as shown in FIG. 9, the optical transmission line is locally bent along the spacer 8, and the transmission loss increases.

Therefore, the backscatter method using the optical pulse tester (the optical pulse tester sends an optical pulse from one end of the optical transmission line, and the reflected pulse returned from the middle of the optical transmission line by Rayleigh scattering is used to transmit the optical transmission line. The method of measuring the loss, loss change in the length direction of the optical transmission line, and the distance to the loss change point) can be used to measure the waterlogged portion.

Here, the optical transmission line is wound around the spacer 8 once,
Shows a structure in which two points of the line are tied with one shrink thread
However, a plurality of optical transmission lines and shrink threads may be used. In addition,
The shape of the sensor is as long as it is locally bent.
Of course, the shape shown in FIG. 7 is not particularly limited. Shrink thread concrete
For example, Kao Soap Co., Ltd. shrink yarn WEY (Wonder Ela
stic Yarn), but the shape of shrink yarn is not limited to thread
Instead, it may be a sheet or a strip. Next, the immersion shown in Fig. 7
Measures the increase in transmission loss when the water detection sensor actually floods
The result will be described.

That is, core diameter / glass outer diameter = 50 μm / 125 μm,
A single optical transmission line with a 0.8 mm outer diameter silicone coating on a silica-based graded optical fiber with a relative refractive index difference of 1% is wrapped around an elliptical spacer with an outer circumference of approximately 210 mm once to form an elliptical long axis. The opposite two points on the side were connected with one WEY contraction thread of about 220 g / piece, and the loss increase with LED light having a wavelength of 1.3 μm was measured. Fig. 10 shows the relationship between the inundation time and the loss increase.

As shown in Fig. 10, a loss increase of about 12 dB was observed about 2 minutes after the inundation, and the loss decreased a little after that, but it stabilized at about 11.6 dB after 4 minutes, and a sufficient back It was confirmed that it is possible to detect the inundation and measure the distance to the inundation point by the scatter method.

The water immersion detection sensor shown in this embodiment can be made highly sensitive by selecting fiber parameters such as increasing the value of the core diameter of the optical transmission line / outer diameter of the fiber and decreasing the relative refractive index difference. Is possible.

High sensitivity can also be achieved by using an optical transmission line with low rigidity or by increasing the contraction force of the contraction yarn. As described above, the water intrusion detection sensor according to the present invention is composed of the optical transmission line and the contraction thread, and is not affected by electromagnetic induction as compared with the one using the conventional conductor, and does not malfunction due to moisture, and thus is resistant to induction. There is an advantage that a highly sensitive sensor can be realized. Further, there is an advantage that the inundation detection and the inundation point estimation can be performed easily and economically only with a simple pulse tester.

The material of the optical fiber is not limited to the quartz type, but may be the plastic type.

Other examples will be shown below.

FIG. 1 shows an example in which one end of a shrinkable yarn is connected to an optical transmission line and the other end is connected to a fixed object, 1 is a shrinkable yarn, 2 is an optical transmission line, 5
Is a holder for holding the optical transmission line loosely.

When this water immersion inspection sensor is flooded, the shrinking yarn shrinks as shown in FIG. 2 and a local bend occurs in the optical transmission line,
Transmission loss increases. In order to increase the transmission loss and improve the sensitivity, it is preferable that the contraction force of the contraction yarn is increased and the distance between the two holders is small.

FIG. 3 shows an example of a water immersion detection sensor in which two shrink yarns are used, one end of which is connected to an optical transmission line and the other end of which is connected to a fixed object. 1 is a shrink yarn, 2 is an optical transmission line, and 6 is an optical fiber. It is a fixture for firmly fixing the transmission line and shrink yarn.

When this water immersion sensor is flooded, the loop formed by the optical transmission line is narrowed down as shown in FIG. 4, and the transmission loss increases. FIG. 5 shows an example of a sensor in which the optical transmission lines are fixed to each other with three shrink yarns, 1 is a shrink yarn, and 2 is a shrink yarn.
Is an optical transmission line, and 6 is a fixture for firmly fixing the optical transmission line.

When this water immersion sensor is flooded, local bending occurs in the optical transmission line as shown in FIG. 6, and the transmission loss increases. It is a matter of course that the embodiments of FIGS. 1, 3 and 5 described above have the same advantages as the advantages described in the example of FIG.

Further, the water intrusion detection sensors shown in FIGS. 3 and 5 are twisted in the optical transmission line due to the contraction force of the contraction yarn when water is infiltrated, and the radius of curvature increases and the loss increase decreases. It is desirable to hold the plate by a holding plate that prevents twisting.

(Effects of the Invention) As described above, since the water detection sensor of the present invention is composed of the optical transmission line and the contraction thread, it is not affected by electromagnetic induction, has no malfunction due to humidity, and has high sensitivity. , Reliable.

In addition, it has an advantage that a highly sensitive sensor can be easily realized by appropriately selecting the optical fiber parameter and the rigidity of the optical transmission line. Furthermore, there is an advantage that the inundation detection and the inundation point estimation can be performed easily and economically only with a simple pulse tester.

[Brief description of drawings]

FIGS. 1, 3, and 5 are plan views of an embodiment of the present invention, and FIGS. 2, 4, and 6 are FIGS. 1 and 3, respectively.
FIG. 5 is a plan view showing the state of the water detection sensor shown in FIG. 5 after water immersion, FIG. 7 is a plan view of an embodiment of the present invention, and FIG. 8 shows the spacer and the holding plate shown in FIG. Fig. 9 is a schematic view of the combination, Fig. 9 is a plan view showing a state after the water infiltration of the water intrusion detection sensor shown in Fig. 7, and Fig. 10 is an infiltration time when the infiltration detection sensor shown in Fig. 7 is inundated. It is a figure which shows the relationship of loss increase. DESCRIPTION OF SYMBOLS 1 ... Shrink thread, 2 ... Optical transmission line 3 ... Spacer, 4 ... Holding plate 5 ... Holding tool, 6 ... Fixing tool

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masaaki Kawase Inventor Masaaki Kawase 162 Shirahane, Shirahoji, Tokai-mura, Naka-gun, Ibaraki Nippon Telegraph and Telephone Corporation, Ibaraki Electro-Communications Research Laboratory (56) References (JP, U)

Claims (1)

[Claims] 1. A local part which connects optical transmission lines with each other by a fiber which contracts when it comes into contact with water, or connects the optical transmission line and another fixed object, and causes an increase in transmission loss in the optical transmission line due to the contracting force of the fiber. A sensor for detecting inundation, which is configured so as to give a realistic bend.