JP2001296111A - Optical handhole lid open / close detection sensor - Google Patents

Abstract

(57) [Problem] To provide an optical handhole lid opening / closing detection sensor with a simple configuration, low loss and low cost. SOLUTION: A signal light is incident on each sensor main body 10 using an approach cable 12 connected to an optical cable via an optical connection part, and the signal light reflected by the FBG 16 is received by a measuring device, so that a handhole is provided. Irrespective of the opening / closing of the lid 11, reflected light can be received at all times, and a strain corresponding to the open / closed state of the lid 11 is applied to the FBG 16 by the strain applying member 21 of the strain applying means 14 to change the center wavelength of the reflected light. Therefore, by detecting the change in the center wavelength, the open / closed state of the lid 11 can be detected without using an optical coupler, whereby the connection loss can be reduced and the cost can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optical handhole cover open / close detection sensor.

[0002]

2. Description of the Related Art There is an optical handhole cover opening / closing detection sensor for detecting opening / closing of a handhole cover using an optical cable.

FIG. 7 is a conceptual diagram of a conventional handhole lid open / close detection system using a conventional optical handhole lid open / close detection sensor.

In this optical handhole lid opening / closing detection sensor system, a pair of optical cables 2a, 2b are connected to a measuring device 1, and the same number of couplers 3a, 3b, 4a, 4b,. Then, the sensor body 6a is connected between the corresponding pair of couplers 3a and 4a via the coupler 5a, the sensor body 6b is connected between the corresponding pair of couplers 3b and 4b via the coupler 5b, and so on. The sensor body is connected between the couplers. Each of the sensor main bodies 6a and 6b is installed in each of the handholes, and uses a Faraday element, an electromagnet, or the like, and a reflection mirror to open and close the handhole cover.
The light 7a incident on the optical cable 2a from the
b, the light returns to the measuring device 1 as reflected light 7b. In the drawings, black circles indicate optical connection parts.

When this system operates, signal light 7a is incident on one optical cable 2a from the measuring device 1, and the signal light 7a is transmitted to each sensor body 6 via couplers 3a, 3b,.
a, 6b,... Each sensor body 6a, 6b,
, The signal light 7a is reflected according to the opening and closing of the lid, enters the other optical cable 2b via the couplers 4a, 4b,... And is reflected by the measuring device 1 connected to the optical cable 2b.
b is detected.

[0006] That is, this system comprises a sensor body 6
Only when a, 6b,... have reacted, the sensor bodies 6a, 6
The reflected light 7b from b,... is returned to the measuring device 1. Normally, there is no reflected light, and the opening / closing of the lid is detected based on the presence or absence of reflection. .. Are distinguished by the return time of the reflected light 7b.

[0007]

However, the above-described conventional optical handhole lid opening / closing detection sensor system has a large light loss due to the use of an optical coupler and reflection / non-reflection processing in the sensor body. For example, since the number of optical connections from the incident light from the measuring device to one sensor main body to the return to the measuring device is eight, the connection loss is 0.8 dB (0.1 dB × 8) and the optical coupler loss Is 1
2 dB (3.0 dB x 4 locations), the loss of the sensor body is 3.0 dB (3.0 dB x 1 location), for a total of 15.8.
dB (excluding transmission path loss).

Further, it is necessary to increase the output of the measuring device and to reduce the minimum light receiving level, which increases the size and cost of the device. Further, when the optical coupler is introduced into an existing system, it is necessary to replace the existing optical connector with an optical connector capable of incorporating an optical coupler, and there is a problem that the construction cost and material cost are enormous.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems and to provide an optical handhole lid opening / closing detection sensor which has a simple structure, has low loss, and is low in cost.

[0010]

In order to achieve the above object, an optical handhole lid open / closed detection sensor according to the present invention detects the open / closed state of a lid with a sensor body installed in a plurality of handholes. In the optical handhole cover open / close detection sensor that propagates the signal light transmitted through the optical cable, the sensor body receives the signal light from the optical cable and reflects the signal light on the optical cable, and when receiving the distortion, changes the center wavelength of the reflected light. And a strain applying means for applying a strain to the reflecting means according to the open / closed state of the lid.

In addition to the above configuration, the reflection means of the optical handhole lid opening / closing detection sensor of the present invention comprises a fiber Bragg grating in which Bragg diffraction is formed on an optical fiber, and the amount of wavelength displacement of the reflected light is connected to an optical cable. It is preferably measured by a wavelength displacement measuring device.

In addition to the above configuration, the strain applying means of the optical handhole lid opening / closing detection sensor of the present invention is provided through a housing installed near the opening in the handhole and a through hole formed in the housing. A strain applying member having a convex cross-sectional shape arranged in the housing such that the protrusion is exposed, and the protrusion is provided between the base of the strain applying member and the inner wall of the housing when the lid is in a closed state. A spring that contacts the lid and biases the strain applying member so that the base contacts the fiber Bragg grating arranged with both ends pulled in the housing when the lid is open and applies strain. The fiber Bragg grating may be constituted by a stopper provided in the housing and for restricting the amount of movement of the strain applying member so that a tension higher than the allowable tension is not applied to the fiber Bragg grating.

In addition to the above configuration, the strain applying member of the optical handhole lid opening / closing detection sensor of the present invention has a gently curved groove at a portion in contact with the fiber Bragg grating so that a uniform force is applied to the fiber Bragg grating. It is preferably formed.

In addition to the above configuration, the distortion applying member of the optical handhole lid opening / closing detection sensor of the present invention is provided with a spherical roller so that a portion in contact with the lid does not apply extra force to the fiber Bragg grating when the lid is opened / closed. Preferably.

In addition to the above configuration, in the optical handhole cover open / close detection sensor of the present invention, the fiber Bragg gratings of the respective sensor bodies are connected in series by an optical cable to simultaneously and continuously measure the open / closed state of a plurality of covers. Is preferred.

According to the present invention, the signal light is incident on each sensor body connected to the optical cable and the signal light reflected by the fiber Bragg grating is received by the measuring device, so that the signal light is always reflected regardless of whether the lid is opened or closed. Since light can be received and the strain according to the open / closed state of the lid is applied to the reflecting means by the strain applying means and the center wavelength of the reflected light changes,
By detecting the change in the center wavelength, the open / closed state of the lid can be detected without using an optical coupler, whereby the connection loss can be reduced and the cost can be reduced.

[0017]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a sectional view showing an embodiment of an optical handhole cover open / close detection sensor according to the present invention, in which a cover of the handhole is closed. FIG. 2 is a plan perspective view of the optical handhole lid opening / closing detection sensor shown in FIG. FIG. 3 is a cross-sectional view showing a state in which the lid of the handhole of the optical handhole lid opening / closing detection sensor shown in FIG. 1 is open.

This optical handhole lid opening / closing detection sensor comprises:
A sensor that detects the open / closed state of the lid 11 with the sensor body 10 installed in a plurality of handholes and propagates the obtained signal light to the optical cable via the approach cable 12. And a reflection means for changing the center wavelength of the reflected light upon receiving the distortion, and applying a distortion to the reflection means 13 according to the open / close state of the lid 11. 14 are provided. The optical cable used for the optical handhole lid opening / closing detection sensor is an optical cable laid or laid for communication. Are connected in the sensor body.

The reflection means 13 comprises a fiber Bragg grating (hereinafter referred to as "FBG") 16 in which Bragg diffraction is formed on an optical fiber 15, and the wavelength displacement of the reflected light is transmitted through the optical fiber 15 and the optical connection. The wavelength is measured by a wavelength displacement measuring device (not shown) connected to the optical cable. 17 is the sensor body 1
This is a waterproof connector for introducing the core wires 18a and 18b of the approach cable 12 into zero.

The strain applying means 14 includes a housing 19 installed near the opening in the handhole, and a projection 21a formed through a through hole 20 formed in the housing 19 on the side of the lid 11 of the handhole. A strain applying member 21 having a convex cross-sectional shape disposed in the housing 19 so as to be exposed, and a base 21 of the strain applying member 21
b and the inner wall of the housing 19, the protrusion 21 a contacts the lid 11 when the lid 11 is in a closed state, and has a base portion on the FBG 16 arranged in the housing 19 when the lid 11 is in an open state. 21
A metal spring (a plate spring is shown in the figure, but a coil spring may be used) 22 for urging the strain applying member 21 so that the strain applying member 21 applies a strain by contact with the b. FB
G16 is configured with stoppers 23a and 23b that regulate the amount of movement of the strain applying member 21 so that a tension greater than the allowable tension is not applied to G16.

The base 21b of the strain applying member 21 is a metal spring 2
2 is bonded with an adhesive. Stoppers 23a, 23b
In the drawing, the length is such that it can contact only the metal spring 22, but may be a length that can contact the base 21 b of the strain applying member 21.

The optical fiber 15 on which the FBG 16 is formed is made of a housing 19 by connecting materials (eg, resin) 25a and 25b.
It is attached in a state of being pulled on both sides inside.

In the strain applying member 21, a gentle curved FBG introduction groove 21c is formed on a base 21b that comes into contact with the FBG 16 so that a uniform force is applied to the FBG 16.
A spherical roller 24 is provided at the tip of the projection 21a.

Next, the operation of the optical handhole cover open / close detection sensor will be described.

As shown in FIG. 1, when the lid 11 of the handhole is closed, the strain applying member 21 is pushed down into the sensor main body 10 by the gravity of the lid 11, and the strain applying member 21 is moved to the FBG 16 having both ends fixed in the sensor main body 10. Has no elongation strain.

However, when the cover (not shown) is open as shown in FIG. 3, the strain applying member 21 is pushed up by the elasticity of the metal spring 22 in the sensor body 10, and the optical fiber 15 And the FBG 16 are guided to the FBG introduction groove 21c formed in the base 21b of the strain applying member 21,
By being pushed up by the gentle curved surface, the entire optical fiber 15 and the FBG 16 are subjected to elongational strain by a uniform force. When this elongation strain is applied, the stopper 23
Since a and 23b regulate the amount of movement of the strain applying member 21, the optical fiber 15 and the FBG 16 are not applied with a tension higher than the allowable tension, thereby preventing the optical fiber 15 and the FBG 16 from being damaged.

Further, since a spherical roller 24 is provided at the tip of the protrusion 21a of the strain applying member 21 (the portion where the strain applying member 21 comes into contact with the lid 11), a hand hole for opening and closing the lid 11 is provided. Even if a horizontal force generated in the lid 11 and the strain applying member 21 due to opening and closing while dragging the lid 11 is applied, the rotation of the spherical roller 24 does not directly transmit the force to the sensor main body 10 and the strain applying member 21. I have.

As described above, it is possible to realize the provision of the optical handhole lid opening / closing detection sensor which has a simple structure, has a small loss, and is low in cost.

FIG. 4 is a sectional view of an optical handhole cover open / close detection system using the optical handhole cover open / close detection sensor shown in FIG.

Sensor bodies 10a to 10d are installed near lids 11a to 11d in hand holes 30a to 30d installed at regular intervals on a road, a high water floor, or the like. Each of the hand holes 30a to 30d is connected by a lateral hole, and is laid in a straight line so that one optical cable 31 passes therethrough. Each hand hole 30a-30
In FIG. 3d, one core of the optical cable 31 is connected to the optical connection portions 32a to 32a to 32d.
It is taken out as approach cables 12a to 12d via 32d, and is connected to each sensor body 10a to 10d, respectively. Each of the sensor bodies 10a to 10d is wired so as to be connected in series with one core taken out from the optical cable 31. A core wire of the optical cable 31 is arranged in the monitoring station and connected to a measuring device 33 for measuring a wavelength displacement. As a result, the sensor units 10a to 10d linearly connected in series are observed by the measuring device 33 as the reflection wavelength change amount of the open / closed state of the lids 11a to 11d of the handholes 30a to 30d. Is displayed on the display terminal 34 in real time, so that remote monitoring can be performed.

(Basis for Optimal Conditions) FBG is used for monitoring the opening and closing of the lids 11a to 11d of the hand holes 30a to 30d.
By applying the measurement of the optical wavelength change amount using 16
The sensor bodies 10a to 10d can be connected in series to a single optical fiber without using an optical splitter or the like.
Since the installation cost of 0a to 10d can be reduced and the loss of the transmission line can be reduced, the measuring device side can be manufactured at low cost.

[0033]

The present invention will be described with reference to specific numerical values, but the present invention is not limited thereto.

FIG. 5 is a conceptual diagram of the optical handhole cover open / close detection system, and FIG. 6 is a partially enlarged view of FIG.
Note that the black circles indicate optical connection parts.

A measuring device 33 is connected to one end (left end) of one of the core wires 31a of the optical cable 31, and an optical connection portion 32a, 32b,. , 12b,... Are connected to the respective sensor bodies 10a, 10b,.

In such a system, the signal light 35 normally incident on the core wire 31a from the measuring device 33 reflects reflected light having a center wavelength determined by the sensor bodies 10a, 10b,. When 10a, 10b,... Change due to distortion (opening / closing of the lid), signal lights 36a, 36b having wavelengths shifted by an amount proportional to the change are reflected. The reflected light is received by the measuring device 33, and the opening and closing of the lid of each handhole is detected.

As shown in FIG. 5, the number of optical connections of this system (the number of connection points that pass from the time when the signal light enters the optical cable from the measuring device to the time when the signal light is received) is four per sensor. For this reason, the connection loss is 0.4 dB (0.1 d
B × 4 places), and the loss of the sensor body 10a is 3.0.
dB (0.1 dB x 1 location), for a total of 3.4 dB
(However, transmission line loss is excluded.), And the connection loss is significantly reduced as compared with the conventional example (15.8 dB) shown in FIG.

(Application Example) The present optical type handhole lid open / close detection sensor is installed at the fully opened / closed position of the gate of the water gate / gutter gate, and a mechanism is used in which an external force is applied to the sensor in the open / closed state of the gate at that time. Thus, the gate opening of the water gate / gutter can be measured. In addition, by connecting this sensor in series to the same optical cable as the optical water level sensor using FBG, it is possible to simultaneously monitor the inner water level, outer water level, and gutter opening of the lock / gutter with one optical fiber. Can be.

In the above, according to the present optical handhole lid open / close detection sensor, the open / closed state of the handhole lid is measured as the amount of change in the center wavelength of the reflected light, so that the introduction cost of the measuring device used for the measurement is reduced. be able to.

[0040]

In summary, according to the present invention, the following excellent effects are exhibited.

It is possible to realize an optical handhole lid opening / closing detection sensor which has a simple structure and has a small loss and a low cost.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an embodiment of an optical handhole cover open / close detection sensor of the present invention.

FIG. 2 is a plan perspective view of the optical handhole lid opening / closing detection sensor shown in FIG. 1;

FIG. 3 is a cross-sectional view showing a state in which a hand hole cover of the optical hand hole cover open / close detection sensor shown in FIG. 1 is opened.

FIG. 4 is a sectional view of an optical handhole lid open / close detection system using the optical handhole lid open / close detection sensor shown in FIG. 1;

FIG. 5 is a conceptual diagram of an optical handhole lid opening / closing detection system.

FIG. 6 is a partially enlarged view of FIG. 5;

FIG. 7 is a conceptual diagram of a conventional handhole lid opening / closing detection system using an optical handhole lid opening / closing detection sensor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Sensor main body 11 Lid 12 Approach cable 13 Reflecting means 14 Strain applying means 16 FBG (fiber Bragg grating) 19 Housing 21 Strain applying member

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Ryosuke Takasaka 880 Sunazawa-cho, Hitachi City, Ibaraki Prefecture Inside the Takasago Plant, Hitachi Cable Co., Ltd. Inside the Takasago Plant (72) Inventor Kenichi Saito 1-6-1 Otemachi, Chiyoda-ku, Tokyo F-term (reference) 2D019 AA54 2F065 AA65 FF48 LL02 LL42 NN06 2H038 AA05 BA25 CA68

Claims (6)

[Claims] 1. An optical handhole lid opening / closing detection sensor that detects the open / closed state of a lid with a sensor body installed in a plurality of handholes and propagates the obtained signal light through an optical cable. Reflecting means for receiving signal light from the optical cable and reflecting the reflected light to the optical cable, and changing the center wavelength of the reflected light when distorted, and applying strain to the reflecting means according to the open / close state of the lid. Means for detecting the opening and closing of an optical handhole cover. 2. The apparatus according to claim 1, wherein the reflection means is a fiber Bragg grating in which Bragg diffraction is formed on an optical fiber, and the wavelength displacement of the reflected light is measured by a wavelength displacement measuring device connected to the optical cable. 2. The optical handhole cover opening / closing detection sensor according to 1. 3. The distortion applying means includes: a housing provided near an opening in the handhole; and a housing provided in the housing such that a projection is exposed through a through hole formed in the housing. The strain applying member having a convex cross-sectional shape arranged in the, the projecting portion contacts the lid when the lid is provided between the base of the strain applying member and the inner wall of the housing, and the lid is in a closed state, A spring for urging the strain applying member so that the base contacts the fiber Bragg grating arranged with both ends being pulled inside the housing when the lid is open and applies strain. The optical handhole cover according to claim 1, further comprising a stopper provided in the housing and configured to restrict a movement amount of the strain applying member so that a tension higher than an allowable tension is not applied to the fiber Bragg grating. Open / close detection sensor. 4. The light according to claim 3, wherein the strain applying member has a gentle curved groove formed at a portion in contact with the fiber Bragg grating so that a uniform force is applied to the fiber Bragg grating. Type handhole lid open / close detection sensor. 5. The strain applying member according to claim 3, wherein a spherical roller is provided so that a portion in contact with the lid does not apply extra force to the fiber Bragg grating when the lid is opened and closed. Optical handhole lid open / close detection sensor. 6. The fiber Bragg grating of each sensor body is connected in series by an optical cable to simultaneously and continuously measure the open / closed state of a plurality of lids.
6. An optical handhole cover open / close detection sensor according to any one of claims 1 to 5.