JPH0476124A - Metallic cover opening and closing sensor - Google Patents

Abstract

PURPOSE:To watch the opening and closing states of a metallic cover by hanging a weight from a wire sandwichedly held between the metallic cover and its supporting base, inserting a wedge formed in a body with the weight between flat plates, and providing an optical fiber between the convex and concave parts of the flat plates for connecting it with a OTDR central device. CONSTITUTION:In the case where a metallic cover 1 has been closed, a wedge 17 is inserted between both flat plates 7,9, and a weight 16 is in a state where it is hanged from a wire 4 to give no stress to an optical fiber 19. When the metallic cover 1 is opened, the wire 4 turns into an about free state to be drawn downward by the weight 16, and falls down along a weight guide 18. The wedge 17 slips down from a spot between both the flat plates 7, 9, and the elastic force of a spring 10 presses the flat plate 9 with a concave part against the flat plate 7 with a convex part to firmly hold the optical fiber 19 between the convex part 14 and the concave part 15 for bending it. Transmission loss at the above part increases, and OTDR(Optical Time Domain Reflector)central device therefore detects the opening of the metallic cover 1.

Description

[Detailed Description of the Invention] [Industrial Field of Application] [Prior Art and Problems to be Solved] As a sensor for monitoring the open/closed state of a metal cover such as a manhole,
Conventionally, for example, proximity sensors or acoustic sensors have been considered.

However, all of the conventional devices require a power source to sense the open/closed state, and also require transmission equipment to transmit the sensed information. For this reason, in order to use conventional sensors in manholes, these power supplies and transmission equipment must also be installed, and there are various problems such as the need to change the design of the manhole in order to install conventional sensors. Ta.

[Means for Solving the Problems] Therefore, the present invention has been made to solve the above problems, and is an 0TDR (Optlcal TIw+e
The present invention provides a metal lid opening/closing sensor that can monitor the open/closed state of a metal lid using a single optical fiber.

Namely, in the sensor of the present invention, a weight is suspended from the other end of a wire whose one end is held between a metal lid and a metal lid holder, and a wedge integrated with the weight is provided with a convex portion and a concave portion, respectively. It is characterized in that it is inserted between two flat plates facing each other and pressed against each other, and an optical fiber connected to the OTDR central device is arranged between the convex portion and the concave portion of the two flat plates.

Alternatively, a weight guide may be provided so that the weight can move only in the vertical direction, and the sensor may be reset by simply pulling up the wire.

[Example] The present invention will be explained below using examples shown in FIGS. 1 to 3. Note that the same reference numerals in each figure indicate the same parts.

Figure 1 shows the sensor of the present invention installed in a manhole.As shown in the figure, the manhole cover has a metal lid (
There is an outer lid 1 and an inner lid 2, each of which is held by a metal lid holder 3. Among these, the present invention is a sensor for monitoring the opening/closing state of the metal lid 1, and a piece of wire 4 is held between the metal lid 1 and the metal lid holder 3 (at 2 tM positions at both ends of the metal lid). .

This wire 4 may be of any type as long as it can hang a weight 16 integral with a wedge 17, which will be described later, and is introduced into the sensor box 6 through a wire protection tube 5 attached along the wall of the manhole.

Here, details of this sensor box 6 will be explained using FIG. 2. This figure is a schematic diagram showing the structure inside the sensor box, and (B) is a sectional view taken along the line AA' in (A).

As shown in the figure, a weight is attached to the other end of the wire 4 through a through hole 8 extending from the upper surface to the lower surface of the flat plate 7 with a convex portion. 6 is installed. This flat plate 7 with convex portions is fixed, and a flat plate 9 with recesses that is movable is arranged opposite to this. This flat plate with a recess is a spring! It is configured so that it is always pressed toward the flat plate with the convex portion by an elastic force of 0. still,
In this embodiment, a spring IO is used to press the flat plates 7.9 together, but the flat plate 7 with convex portions and the flat plate with concave portions 9 may be made of a magnetic material that attracts each other.

Further, an insertion hole II is provided on the spring side of the flat plate 9 with a concave portion, into which a support shaft I2 having the spring fitted thereon is inserted. Therefore, even if the flat plate 9 with concave portions moves toward the flat plate with convex portions, the flat plate 9 with concave portions will not fall off the support shaft 12.

Furthermore, two groove-shaped wedge guides 13 extending from the upper surface to the lower surface of each of the flat plates 7 and 9 are provided on each opposing surface of the flat plates 7 and 9, as shown in FIG. This serves as a guide when the wedge 17 that will be inserted later is inserted between the flat plates 7 and 9. In particular, a cutout 13a is provided at the lower end to fit the analyzing end so that the wedge 17 can be easily inserted. It is being

Then, on the opposing surfaces of each flat plate 7.9, between the two wedge guides +3, the flat plate 7 with a protrusion has a protrusion I
4, the flat plate 9 with a recess is provided with a groove-shaped recess 15 that fits the protrusion I4 (see figure (B)).

On the other hand, the weight 1G is provided with two rod-shaped wedges 17 having wedge-shaped tips, which are connected to the wedge guide +
3 between the two flat plates 7.9.

Moreover, a weight guide 18 is provided on this weight 6 so that the wedge 17 can be pulled out and removed between the flat plates 7 and 9. This is constructed by opposing rod-shaped objects with a U-shaped cross section and sandwiching both sides of the weight 1B, but it may also be constructed of rod-shaped objects that pass through the weight tS. This weight guide 18 allows the weight 1B to move only in the vertical direction at the bottom of both flat plates 7.9, so that the weight te falls and the wedge I7 moves to both flat plates 7.9.
, 9, the wedge 17 can be reinserted between the flat plates 7, 9 by simply pulling up the wire 4 again.

A looped optical fiber 19 is placed between two wedges 17 inserted between the convex portion 14 and the concave portion 15 of both flat plates of such a mechanism. This loop-shaped optical fiber 19 is drawn out to the outside of the sensor box, and one end is connected to another sensor box, and the other end is connected to the OTDR central device 20 (see FIG. 3).

0TDR is a technology widely used for measuring optical fiber loss distribution and investigating fault points. It consists of an optical fiber that is connected to the device and serves as a sensor section. Then, by inputting a light pulse from a laser light source into an optical fiber and measuring the delay time of the backscattered light (the time from when the light pulse is input until the backscattered light returns to the input end), backscattered light can be detected. The transmission loss of the optical fiber at each position is determined by determining the generation position of light (normally Leh scattered light is used) and detecting the intensity of the backscattered light. Therefore, with this technique, it is possible to obtain continuous loss distribution data in the length direction of the optical fiber.

When the optical fiber loss is measured using the above sensor, when the metal lid 1 is closed, the wedge 17 is connected to both the plates 7 and 9.
Since the weight 16 is inserted between the two and suspended by the wire 4 and does not apply any stress to the optical fiber 19, no particularly large transmission loss points are observed.

However, when the metal lid 1 is opened, the wire 4 becomes almost free and is pulled downward by the weight of the weight I[i.

Here, the wire 4 is sandwiched between the inner cover 2 and its support, but since the inner cover itself is light, the weight 7 cannot be suspended, and the elasticity of the spring 10 Due to the force, the weight 16 and the wedge 17 integrated with each other are sandwiched between the two plates 7 and 9, but this is not strong enough to hold the weight 16, so the weight 1B is removed by opening only the metal lid 1.
will fall.

Now, as mentioned above, when the wire 4 becomes free, the weight 1
B falls along the weight guide 18, and the wedge 1 integrated with it
7 is completely removed from between the 7 and 9 boards in both years. Then,
Since the wedge 17 that separated the two plates 7 and 90 is gone, the flat plate 9 with concave portions is pressed against the flat plate with convex portions 7 by the elastic force of the spring IO, and the optical fiber is connected between the convex portions 14 and the concave portions 15. He pinches Han and gives him a bend. As a result, the transmission loss in the bent portion increases, and this is transmitted to the OTDR central device 20.
By measuring this, it is possible to detect that the metal lid has been opened.

When closing the metal lid 1, the weight 1G is pulled up using a long wire 4, and one end of this wire 4 is sandwiched between the gold Ml and the metal lid holder 3. In this case, the weight IB is suspended in the air and is pulled up along the weight guide 18 without rotating, so this and the wedge 17 of the body are wedge guides! 3, it will be inserted between the two plates 7 and 9 again. In addition, before lifting weight 1 [i, both years board 7.
There is a gap for the optical fiber sandwiched between 9,
Notch 1 at the lower end of the wedge guide 13 that fits the tip of the wedge +7
3a, the wedge 17 can be reinserted more easily.

In this way, by using this sensor, you can monitor the open/closed state of the metal lid with a single optical fiber, and when you close the metal lid, you can simply pull up the wire 4 and restart the sensor so that you can monitor the open/closed state again. You can also set it.

[Effects of the Invention] As explained above, according to the sensor of the present invention, by using only one optical fiber, the open/closed state of the metal cover can be determined without installing a power source for the sensor or a device for transmitting information obtained by the sensor. can be monitored.

Furthermore, the sensor can be reset by simply pulling up the wire on which the weight is suspended and inserting one end of the wire between the metal lid and the support.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram showing the sensor of the present invention installed in a manhole, Figure 2 (A) is a schematic diagram showing the structure inside the sensor box, and (0) is a sectional view taken along Figure A-A' (A). FIG. 3 is an explanatory diagram showing the state in which this sensor is connected to the OTDR central device. 1...Golden lid, 2...Inner lid, 3...Golden lid holder, 4
... wire, 5 ... wire protection tube, 6 ... sensor box, 7 ... flat plate with convex part, 8 ... through hole, 9 ...
...Flat plate with recess, 10...Spring, II...Insertion hole, 12...Spindle, 13...Wedge guide, 13a...
...Notch, I4...Protrusion, 15...Concave, 16.
...Weight, +7...Wedge, +8...Weight guide, 19
...Optical fiber, 20...OTDR central device.

Claims (2)

[Claims] (1) A weight is hung from the other end of the wire, which is held between the metal lid and the metal lid holder, and a wedge integrated with this weight, each having a convex part and a concave part, are pressed against each other. Match 2
A metal lid opening/closing sensor characterized in that it is inserted between two flat plates, and an optical fiber connected to an OTDR central device is disposed between a convex portion and a concave portion of the two flat plates. (2) The lid opening/closing sensor according to claim (1), further comprising a weight guide so that the weight can move only in the vertical direction.