JPH04115205A - Cable for detection - Google Patents

Abstract

PURPOSE:To detect physical quantities of a side pressure, temp., etc., and to enable replacement and route changing by constituting an optical fiber detector of pipe cables and optical fibers. CONSTITUTION:Pipelines 12 are connected by fitting of connectors 13 according to the laying route of the optical fibers and the pipe cables 14 consisting of a resin, etc., are provided on the outer peripheries thereof to coat and hold the pipelines. These pipelines 12 are internally hollow. The optical fibers 15 are formed by forming a coating layer 17 consisting of a thermosetting type silicone resin on the outer peripheral part of multimode fibers 16 made of silicon glass and coating the outer periphery thereof with a foamed polyethylene layer 18 in the stage of aggregating two pieces of such fibers. The optical fibers 15 are inserted into the pipe cables 14 after the end of laying. The optical fibers are delivered into the pipelines 12 by means of driving pinch rollers and the gas having the velocity higher than the delivery speed is force fed by a compressor 19 to transport and insert the optical fibers to a downstream direction by the viscous resistance generated with the flow of the gas or the pressure difference generated in the pipelines 12, by which the cable 11 for detection for detecting the physical quantities is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a detection cable laid over a wide area, for example for crime prevention or disaster prevention.

<Prior art and problems to be solved by the invention> Conventionally, as a detector using an optical fiber, OTDR (Opt
ical Time Domain Reflo
Temperature detectors (see Japanese Patent Application Laid-open No. 1-140031) and lateral pressure detection M (see Japanese Patent Application Laid-Open No. 61-242214), etc., have been developed using the ctometry method and optical fibers.

By the way, these detectors are effective when laying optical fibers over a wide area in a planar manner, but in reality,
The number of cable connection points increases, transmission loss increases, and the cable length is abnormally long, making it difficult to widely apply due to installation problems.

To explain this using FIG. 7, when installing a security sensor in the area (for example, 100 m x 100 m) shown in FIG.
When setting as shown in l), in the conventional method,
Generally, as shown in Figure 7 (bl), five trunk cables 101 are drawn from A1 to E1, and connected to A5 to AI.
.

85~Bl, C5~CI, D5~DI, E5~E1 5
A method is used in which two cables 102 are connected and each other end is connected to form a continuous length. in this case,
The contact point of the optical fiber core is 15 as shown in Figure 7 (bl).
It becomes a point.

Also, the loss at the connection point is 0.0 with 7 germ fibers.
2dB/point, fiber loss 0.4dB/k
If you add up all the 15 connection points, you will have a fiber loss of 3 dB, which is equivalent to 7 km of optical fiber. It will be far more than that.

In order to avoid this problem, according to the conventional method, a method of laying a straight cable 103 as shown in FIG. There is a U theme that long laying is difficult.

Furthermore, in these conventional methods, once the optical fiber, which is a sensitive detector, has been installed, it is not replaced or inspected even if it deteriorates due to heat or lateral pressure. In addition, in the conventional method, the measurement S path and the order to the measurement are fixed (-), so the measurement point is It may be unnecessary or may be needed in the future! ,
If there is a problem, it is necessary to install a cable with a long length I5 even if it is not necessary to measure that point at the time of measurement. There is a problem with this.

Means for Solving the Problems> A detection cable according to the present invention that solves the above problems is a detection cable that is laid over a wide range and measures each cover burial at a desired position, and includes: It is characterized by having a pipe cable having a conduit, and an optical fiber that is inserted and recovered by pressure fluid into the conduit.

The present invention will now be described in detail.

The detection cable of the present invention can be laid over a wide range and has extremely small errors in physical quantities at desired positions, particularly for lateral pressure sensors and temperature sensors.

This is suitable for use as a gas concentration sensor.

The outline of the detection cable 11 will be explained using FIG. Connection is made by fitting a connector 13, and a pipe cable 14 made of resin or the like is provided around the outer periphery of the conduit 12 to keep the conduit 12 covered.
The interior thereof is hollow, and the optical fiber 15 is inserted therein using a pressure fluid by a method described later.

As shown in FIG. 1(b), this optical fiber 15 has a coating layer 17 made of thermosetting silicone resin around the outer periphery of a silicon glass multimode fiber core 16 having an outer diameter of 125 μm.
is formed to have an outer diameter of 300 μm, and the outer periphery of the assembled two pieces is covered with a foamed polyethylene layer 18 as a foamed layer.

After the installation of the pipe cable 14 having the conduit line 12 is completed, this optical fiber 15 is installed using the known technique disclosed in Japanese Patent Laid-Open No.
According to the method disclosed in Japanese Patent No. 9-104607, the gas is inserted into the pipe 12 by a drive pinch roller (not shown), and the gas having a velocity greater than its delivery distance is pumped by the collector 19. As a result, the detection cable 11 that is conveyed downstream and inserted through the W path 12 due to viscous resistance generated between the gas flow or the pressure difference generated within the W path 12 to detect a physical quantity is formed.

Function〉 The detection cable ζ, which detects physical quantities, consists of a pipe cable including one or more conduits and an optical fiber inserted and collected through the pipe cable by a flow of pressure fluid. A long detector can be installed without making any connections, and the connection loss can be kept very small compared to conventional cables that are connected at several locations. It is particularly effective for use in optical cables for sensors such as 1 degree or lateral pressure, where fluctuations in the refractive index distribution of the connection or slight deviations in the optical path can have a large effect as errors in measured values.

In addition, compared to installing a series of long cables as in the conventional method, it is easier to install short length cables (eve cables), and the optical fibers are less susceptible to deterioration due to heat and lateral pressure from the object to be measured. In addition, when inspection or calibration is required, by flowing air into the vibrator, the optical fiber can be sent out and retrieved or replaced. The installation form of the conduit can be easily changed by attaching and detaching the connector to be connected. Therefore, taking advantage of the ease of changing and replacing the conduit form, it is possible to install the vibe cable in advance and change its connection. Since the optical fiber detector can measure only the necessary measurement points, it is possible to measure physical quantities with the least amount of error.

<Embodiment> Hereinafter, an embodiment of the detection cable of the present invention will be explained.

Example 1 (Specific Example of Pressure Sensor) An example of MM of a pressure sensor that detects the passage of a vehicle will be shown. Figure 2 (d+ shows the installation route for the pressure sensor.
,)reactor. In this example, there are three gates (gate
Between B and E, between gate ■C and F, between gate ■D and G),
Pipe line 2 having a hollow passage 21 as shown in FIG. 2(a)
An optical fiber detector 24 for measuring lateral pressure, which is formed by inserting an optical fiber 23 into the inside of the sensor 2, is installed.

In addition, there are other parts where lateral pressure is not measured (between A and 8).

A synthetic resin conduit 25 shown in FIG. 2 (61) is installed between B and C and between C and D, and an optical fiber 23 is inserted inside.

That is, an optical fiber detector 24 for lateral pressure sensor as shown in FIG. 2(a) is installed at the gate part where measurement is required.
Two lines are installed between E, two lines between C and F, and one line is installed between D and C. At point X, shown in the installation route as shown in Figure 2 Conduit 2 due to connection
2, 22, and pipes 22 and 25 were connected to form a series of pipes.

Pipe line 22 used for the optical fiber detector 24 for measuring the lateral pressure
The material is a rubber material that can be easily deformed elastically.
The optical fiber 23 is easily deformed by the application of air pressure during transport and recovery, and as shown in FIG. ing.

Here, as shown in FIG. 2 (C1), the optical 7 anova 23 is made by forming a coating layer 31 with a thermosetting silicone resin on a multimode fiber core 30 made of silicon glass with an outer diameter of 125 μm and having a diameter of 300 μm. Two pieces arranged in parallel are integrated using the same thermosetting silicone resin and further covered with a foamed polyethylene layer 32, and the diameter thereof is 2III11.

This optical fiber 23 is connected to a conduit with a total length of 700 m, A-B, B
-E, E-B, B-C, C-F.

In the sections F-C, C-D, and D-G, the pressure is 8 kg/
The cables were laid continuously using compressed air. The installation took only 22 minutes.

Fig. 2 (fl shows the cross section of the detection part of the gate actually installed. A steel plate z7 is placed on a plurality of (two in this example) optical fiber detectors 24, and lateral pressure is applied. It allows you to take more time.

After installing such a detection cable, an optical pulse test board having a generating means for generating optical pulses and a detecting means for detecting backscattered light is installed in the measurement building 26 shown in FIG. It was connected to one optical fiber core 31 in the optical fiber 23, and the backscattered light intensity was measured. The results are shown in FIG. 3 (horizontal axis is distance, II axis is backscattered light intensity). FIG. 3(a) shows a state in which no lateral pressure is applied to the detector, and FIG. 3fbl shows the measurement results when a vehicle passes over the gate (2). In fbl of the same figure, a level difference in the intensity of backscattered light was observed at a point corresponding to gate (2), and its ability as a detector was confirmed.

Next, we conducted a test in which compressed air at a pressure of 8 kg/(!I11') was sent from point G at the end of the cable, and the optical fiber 23 was moved toward point A and recovered. We were able to perform the recovery.

In addition to the lateral pressure sensor, for example, the pipe line 2 of the lateral pressure detection section
It is also possible to use a known water-absorbing material in 2 to make a water immersion sensor, and it is also useful to use it in combination with a mechanism that converts other known physical quantities into temperature or lateral pressure.

Example 2 (Specific Example of Temperature Sensor) An example of manufacturing a temperature sensor for measuring a local temperature rise in piping within a pill will be described.

FIG. 5 (A1 shows the installation route of the sensor. In this example, E, F, G.

As shown in Figure 5 (al), connect piping 40 to each detection point H and I.
The pipe line 41 is wound spirally around A to 40C, and the pipe line 41
The optical fiber 23 was passed through the pipe 41 (total length: 600 mj) in the same manner as in Example 1 using compressed air at a pressure of 8 kg/m. This passage took 27 minutes. .

In this pipe installation, as shown in Fig. 4 far,
The installation route can be constructed by connecting the pipe line 41 wound around 0 with the connector 42 at one end of the pipe line 41.
Root formation was easy.

As a result of flowing hot water into the pipe 40 and evaluating the temperature at each point using the 0TDR linear temperature distribution measurement system method (see Japanese Patent Application Laid-open No. 1-140031), the temperature at each point was determined to be different at the same time. The temperature measured using a thermocouple at the point was in close agreement with the temperature measured using a thermocouple, showing good characteristics as a temperature detector (Fig. 6 (a)
)reference).

Next, the optical fiber 23 is recovered by sending compressed air from the front of the route, and the connection of the connector 42 of the conduit 41 of the measurement route shown in FIG. 30 temperature detection routes excluding 940B and IOC
The distance was shortened to 0 m, and the temperature was measured using backscattered light measurement @43 as before.

As shown in FIG. 4 (bl), the optical fiber 42 has a single fiber core 31 consisting of a near fiber and a cladding in the optical fiber 23 shown in Example 1, and a thermosetting resin layer 31.
A nylon layer 44 is provided between the foamed polyurethane layer 32 and the foamed polyurethane layer 32 for reinforcement.

This measurement result is shown in Figure 6 (bl.fb), which is higher than the previously measured value (see Figure 6+8.).
, measurement results with less noise were obtained.

Here, for the detection part of the above-mentioned temperature sensor, it is recommended to use a metal conduit such as copper with good thermal conductivity, and to put a good thermal conductor such as silicone oil in the conduit. , which is effective in increasing detection ability.

<Effects of the Invention> As described above with the embodiments, the detection cable according to the present invention detects physical quantities such as lateral pressure and temperature by configuring an optical fiber detector with a pipe cable and an optical fiber. It can be confirmed that it has superior characteristics compared to conventional optical fiber detectors, and is effective because it can be replaced or routed freely.

In addition, when used as a lateral pressure sensor, the area to which lateral pressure is applied is limited, and damage often occurs locally, but the optical fiber may be moved or recovered as necessary to avoid damage to the same area. It can be installed and used, and the life of the cable is much longer5) than that of conventional cables.

Furthermore, when used as a temperature sensor, it is necessary not only to detect a detection area with a wide area, but also to connect many cables in the longitudinal direction. 5) It is also effective when it is desired to combine a power supply cable and a JA degree sensor.

[Brief explanation of drawings]

Figure 1 (a) 1 Detection cape? Schematic diagram, Figure 1 (
bl is a configuration diagram of the optical fiber, FIG. 1 (C) is a laying route diagram of the optical fiber, FIG. Characteristic diagrams used as a lateral pressure sensor according to the first embodiment, FIGS. 4 and 5 are schematic diagrams according to the second embodiment as a temperature sensor of the present invention,
Fig. 6 is a characteristic diagram used as a temperature sensor according to the second embodiment, and Fig. 7 is a schematic diagram showing an example of installing a conventional detector. In the drawing, 1" is a detection cable, 12 is a conduit, 13 is a connector, 14 is a pipe cable, 15 is an optical fiber, 1.6.30 is a fiber core, 17.31 is a coating, 1. 18. 32 is foamed polyethylene, 1 19 is a compression saucer, 21 is a hollow passage, 22. is a 25-t conduit, 23 is an optical fiber, 24 is an optical fiber detector, 26 is a measurement building, 40. 40A to 40C are piping , 41 is a conduit, and 42 is a connector.

Claims (1)

[Claims] A detection cable laid over a wide area to measure various physical quantities at desired locations, comprising a pipe cable having one or more conduits, and a pipe cable inserted into the conduits by pressure fluid. - A detection cable characterized by having an optical fiber that is recovered.