JP4879217B2 - Optical signal determination device - Google Patents

Description

  The present invention relates to an optical signal determination apparatus using an optical communication cable, and more particularly to an optical signal determination apparatus capable of avoiding the influence of condensation in a transmission / reception unit.

In city gas supply, a slam shut valve (hereinafter referred to as SSV) is used as a remote gas shutoff system in the event of a disaster such as an earthquake. The SSV has both a governor function and a shut-off function. The SSV is shut off when the governor secondary side abnormally boosts, and can be shut off by remote operation in an emergency as will be described later.
Conventionally, the SSV has not been provided with means for electrically determining whether the valve is opened or closed by remote operation. Therefore, when a remote shut-off operation is performed, it must be determined that the shut-off signal is shut off when the shut-off signal is output. There was a problem that it was not possible to confirm whether or not the valve was closed.

In order to deal with this problem, a system has been proposed in which a reflecting plate is attached to the tip of the return lever of the SSV, and an optical signal is applied to the reflecting plate to determine the valve shut-off state based on light reflection and non-reflection.
FIG. 11 shows an optical signal determination apparatus 100 according to this technology, and includes a sensor fiber cover 101a on a transmission side optical fiber cable (hereinafter referred to as an optical cable) 101a, a reception side optical cable 101b, and a valve (not shown). The reflecting plate 103 fixed to the valve return lever 104 in 105 and the light transmitting / receiving unit 102 are the main components. When the valve is opened, the reflecting plate 103 is positioned at a right angle to the optical axis as shown in FIG. At this time, the optical signal transmitted from the transmission side optical cable 101a is reflected by the reflecting plate 103, returns to the light transmitting / receiving unit 102, and transmitted to the monitoring device (not shown) via the reception side optical cable 101b. Determined. On the other hand, when the valve is closed, it is determined that the valve is closed because it is parallel to the optical axis as shown in FIG. By using such an optical signal determination device, it has become possible to remotely confirm the presence or absence of valve shutoff based on the shutoff signal output.
Gas Energy Newspaper, 2007.11.28, “Tosetsu confirms reliable valve closing SSV optical switch”

    However, in SSV, since a rapid pressure drop from the governor primary pressure (0.1 to 1 MPa) to the secondary pressure (about 2 kPa) occurs, the SSV main body is cooled by adiabatic expansion of the gas. Furthermore, since the SSV is often installed in a highly sealed room such as a basement, the optical signal determination device attached to the SSV is often placed in an environment where condensation is likely to occur. There is a possibility that water droplets accumulate in a polka dot shape and hinder normal judgment.

The present invention is intended to solve such a problem, and provides an optical signal determination device that can operate normally even if the light transmitting / receiving unit is condensed with a simple structure. The gist of the present invention is as follows. That is, the optical signal determination device according to the present invention is
(1) An optical signal determination device that includes a pair of a transmission-side optical cable and a reception-side optical cable having a light transmission / reception unit at a distal end, and that determines a detection target state based on a reflected light reception ratio with respect to a transmission optical signal, A tip cap protruding from the light transmitting / receiving unit is further provided, and a recess depth formed by the inner edge of the tip cap and the end surface of the light transmitting / receiving unit is configured to avoid formation of spherical water droplets due to condensation on the light transmitting / receiving unit. It is characterized by comprising.
(2) The transmission side optical cable and the reception side optical cable are bundled together.
(3) The tip cap material is elastic rubber (for example, silicon rubber).
(4) In the above (1) to (3), the optical signal determination device is mounted on the gas slam shut valve, and the reflecting plate for reflecting the transmitted optical signal rotates in conjunction with the valve blocking rotation shaft. It is characterized in that it is mounted at a position separated from the optical axis so as not to reflect the transmitted optical signal when the valve is shut off.

According to each of the above inventions, even when the apparatus is placed in a dew condensation environment, water droplets do not accumulate in the form of polka dots on the light transmission / reception unit, and an accurate determination can be made.
Further, in the invention mounted on the gas slam shut valve, since the reflection plate does not reflect the transmission optical signal when the valve is shut off, there is no possibility of erroneous determination.

Hereinafter, embodiments of the present invention will be described in more detail with reference to FIGS. Needless to say, the scope of the present invention is described in the claims and is not limited to the following embodiments.
FIG. 1 is a diagram showing an overall configuration of a remote gas cutoff determination system 40 including an optical signal determination device according to an embodiment of the present invention. FIG. 2 is a diagram showing an external configuration of the slam shut valve 10. FIG. 3 is a schematic diagram of a cross-sectional configuration of the slam shut valve 10. FIG. 4 is a view showing a valve shut-off state of the slam shut valve 10. FIG. 5 is a diagram illustrating a cross-sectional configuration of the blocking detection unit 20. FIG. 6 is a diagram illustrating a connection mode of the reflecting plate 24 to the return lever 14. FIG. 7 is a diagram illustrating the overall configuration of the optical signal determination device 1. FIG. 8 is a diagram illustrating a detailed configuration of the tip portion of the optical signal determination device 1. FIG. 9 is a diagram showing a valve shutoff determination method in the present embodiment. FIG. 10 is a diagram illustrating a water droplet formation process in the light transmitting / receiving unit 8 when the optical signal determination device 1 is in a dew condensation environment.

  Referring to FIG. 1, a remote gas shut-off determination system 40 includes a slam shut valve (hereinafter referred to as SSV) 10 interposed in a gas flow path, a shut-off detection unit 20 that detects whether or not SSV is shut off, and a remote that instructs the SSV 10 to shut off. The monitoring device 30 is provided as a main component. The remote monitoring device 30 instructs the SSV 10 to shut off based on a remote command from a center (not shown), and further transmits an optical signal to the remote command unit 31 that sends the shut-off determination result to the center and the shut-off detection unit 20. An amplifier unit 33 that transmits and converts a return optical signal into an electrical signal, a determination unit 32 that determines the presence or absence of blocking based on a transmission / reception signal, and a negative pressure blocking unit 34 that applies a negative pressure to the SSV 10 are provided. Yes.

  2 and 3, the SSV 10 includes a valve portion 11 and a governor portion 12 disposed above the valve portion 11. The interior of the governor 12 is divided into two chambers via a diaphragm 12d. In the upper chamber 12e, a spindle 12b penetrating the diaphragm 12d and a biasing spring 12a are accommodated on the outer periphery of the spindle 12b. Further, a negative pressure introduction port 12h at the time of emergency shutdown described later is provided. A ball latch mechanism 12c is accommodated in the lower chamber 12f. The lower chamber 12f is configured so that a governor secondary pressure is applied through the introduction port 12g, while the spring 12a is set to have a spring constant so as to balance the governor secondary pressure.

The valve unit 11 includes a swing valve 11b, a stem 11e, and a spring 11d. One end side of the swing valve 11b is rotatably fixed to the rotation shaft 11f. The rotation shaft 11f protrudes outside the main body and is rotatably fixed by a shaft support nut 15. A return lever 14 is attached to the tip of the rotating shaft 11f. A shut-off detection unit 20 is attached to the outer periphery of the shaft support nut 15. A hook 11c for suspension to the stem 11e is provided on the upstream side surface of the swing valve 11b. A valve seat 11g is provided in the internal gas flow path, and the gas flow path is blocked by the contact of the swing valve 11b.
The spindle 12b and the stem 11e are connected via a ball latch mechanism 12c, and the stem 11e is held at the swing valve 11b open position by the ball latch mechanism 12c when supplying gas. Further, when the upper chamber 12e is under negative pressure, as shown in FIG. 4, the spindle 12b is lifted upward to release the latch, and the stem 11e is moved downward by the action of the spring 11d. Along with this, the hook 11c is released and the swing valve 11b is rotated to come into contact with the valve seat 11g to block the gas flow path. As the swing valve 11b rotates, the return lever 14 also rotates 90 degrees counterclockwise.

Next, the configuration of the shutoff detection unit 20 will be described with reference to FIGS. 5 and 6, the shutoff detection unit 20 is fixed to the sensor cover 26 fixed to the shaft support nut 15, the reflector 24 fixed to the return lever 14 via the attachment 25, and the sensor cover 26. Pedestal 27 and the optical signal determination device 1 fixed to the pedestal 27 by the tightening nut 23. The inner surface of the sensor cover 26 is blasted to prevent saturation reflection. The reflecting plate 24 is fixed to the outer peripheral portion tangent position of the attachment 25 by the mounting portion 24a. As will be described later, this position is set so as to be perpendicular to the optical axis in the opened state of the swing valve 11b, parallel to the optical axis in the closed state, and sufficiently separated from the optical axis.
7 and 8, the optical signal determination device 1 includes a fixing nut 4 at the center, a main body 2 having a through hole therein, an optical cable 3 through which the through hole is inserted, and a tip 7. A silicon rubber cap 6 is provided as a main component. A screw 5 for the tightening nut 23 is cut at the distal end side of the fixing nut 4. The distal end portion 7 is configured to have a smaller outer diameter with respect to the other portions so that the outer diameter is the same as that of the other portions when the cap 6 is inserted. In the optical cable 3, the transmission side optical cable 3a and the reception side optical cable 3b are bundled together, and the caulking 10 is fixed to the inner surface of the through hole. The light transmission / reception unit 8 at the front end of the optical cable 3 is disposed at a position recessed with respect to the front end surface of the cap 6, and a recess 9 is formed by the inner edge surface of the cap 6 and the light transmission / reception surface 6.

The remote gas shutoff determination system 40 is configured as described above. Next, the valve shutoff determination method in the present embodiment will be described with reference to FIG. While the system is operating, an optical signal is always transmitted from the amplifier unit 33 via the transmission side optical cable 3a. When the valve is open, the reflector 24 is perpendicular to the optical axis as shown in FIG. 5A. Therefore, the light emitted from the light transmitting / receiving unit 8 is reflected by the reflector 24, and the reflected light is large. The portion is captured by the light transmitting / receiving unit 8. The determination unit 32 confirms valve opening by comparing the received light amount / transmitted light amount.
When the governor upper chamber 12e becomes negative pressure by the negative pressure cutoff unit 34 based on the cutoff command from the remote monitoring device 30, the swing valve 11b is closed as described above. Accordingly, since the rotation shaft 11f rotates 90 degrees, the reflecting plate 24 is parallel to the optical axis and sufficiently separated from the optical axis as shown in FIG. Therefore, the light emitted from the light transmitting / receiving unit 8 reaches the inner surface of the sensor cover 26 without being reflected by the reflecting plate 24. Since the inner surface is blasted, the amount of light scattered and reaching the light transmitting / receiving unit 8 is less than the threshold for the amount of radiated light, and the determination unit 32 determines that the valve is closed.

  Next, referring to FIG. 10 as well, the influence of dew condensation on the light transmitting / receiving unit 8 when the optical signal determination device 1 is in a dew condensation environment will be described. When the periphery of the light transmission / reception unit 8 is below the dew point, minute water droplets are generated in the concave portion 9. In this case, since the depth (d) of the concave portion 9 is sufficiently large, the water droplet is formed in a thin film shape and covers the surface of the light transmitting / receiving portion 8. In addition, due to capillary action, the cap 6 and the inner surface of the main body enter the gap 2b and are discharged in the direction of the screw portion 5 and do not accumulate excessively in the recess 9. Due to these synergistic effects, water droplets do not grow in the shape of polka dots on the surface of the light transmitting / receiving unit 8 and do not affect the blocking determination.

  INDUSTRIAL APPLICABILITY The present invention can be widely used as a dew condensation countermeasure technique for a transmission / reception unit in a determination device using an optical communication cable as well as a remote shutoff determination device for a slam shut valve.

It is a figure which shows the whole structure of the remote gas interruption | blocking determination system. 1 is a diagram showing an external configuration of a slam shut valve 10. FIG. 1 is a schematic diagram of a cross-sectional configuration of a slam shut valve 10. FIG. FIG. 3 is a view showing a valve shut-off state of the slam shut valve 10. FIG. 3 is a diagram showing a partial cross-sectional configuration of a shutoff detection unit 20. It is a figure which shows the connection aspect to the return lever 14 of the reflecting plate 24. FIG. 1 is a diagram illustrating an overall configuration of an optical signal determination device 1. FIG. It is a figure which shows the detailed structure of the optical signal determination apparatus 1 front-end | tip part. It is a figure which shows the valve interruption | blocking determination method in this embodiment. It is a figure which shows the water droplet formation process in the light transmission / reception part 8 when the optical signal determination apparatus 1 exists in a dew condensation environment. It is a figure which shows the valve cutoff determination method of the conventional optical signal determination apparatus 100. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Optical signal determination apparatus, 3 ... Optical cable, 3a ... Transmission side optical cable, 3b ... Reception side optical cable, 4 ... Fixing nut, 5 ... Screw part, 6 ... Cap 9 ... Recess, 10 ... Slam shut valve, 11a ... Gas flow path, 11b ... Swing valve, 11c ... Hook, 11d, 12a ... Spring, 11d ... Spring, 11e ... stem, 11f ... rotating shaft, 11g ... valve seat, 12 ... governor, 12b ... spindle, 12c ... ball latch mechanism, 12d ... diaphragm, 12e ..Upper chamber, 12f ... Lower chamber, 12g ... Secondary pressure inlet, 12h ... Negative pressure inlet, 14 ... Return lever, 15 ... Shaft support nut, 20 ... Blocking detection unit 23 ... Clamping nut 24 ... Reflector plate 25 ... Attachment 26 ... Sensor cover 27 ... Base 30 ... Remote monitoring device 31 ... Remote Command unit 32... Determination unit 33... Amplifier unit 34. Negative pressure cutoff unit 40. Remote gas cutoff determination system

Claims (1)

An optical signal determination device comprising a pair of transmission side optical cable and reception side optical cable having a light transmission / reception unit at a distal end portion, and performing a state determination of a detection target based on a reflected light reception ratio with respect to a transmission optical signal,
A tip cap protruding from the light transmitting / receiving unit,
In addition, the depth of the recess formed by the inner edge of the tip cap and the end surface of the light transmitting / receiving unit is set to a depth that allows water droplets to be formed in a thin film shape, and from the gap between the tip cap and the outer peripheral tip of the transmitting / receiving unit. by water drops configured to be discharged from the tip of the transmitting and receiving optical portion by capillary action, and can avoid the formation of spherical water droplets due to condensation in the feed light receiving unit,
The reflection plate that reflects the transmitted light signal is fixed integrally to the outer periphery of the attachment fixed to the valve blocking rotation shaft, and rotates in conjunction with the valve blocking rotation shaft. Installed at a position away from the optical axis without reflecting the transmitted optical signal,
An optical signal determination device characterized by comprising:

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