JPH03181832A - pressure sensor - Google Patents

Abstract

PURPOSE:To accurately detect the pressure change of a fluid by embedding an optical fiber strand in the wall of a tube having flexibility to fix the same to both ends of the tube and providing a casing having a ring restricting the expansion of the tube to the tube. CONSTITUTION:An optical fiber strand 2 is embedded in the wall of a tube 1 having flexibility composed of rubber in the axial direction of the tube 1. Both ends of the tube 1 is fixed by a casing 3 and a ring 4 for restricting the expansion of the tube 1 is provided to the central part of the casing 3. The fluid inflow port 3A communicating with the tube 1 is provided to one end of the casing 3 and the other end of the casing 3 is closed by a blind plate 6. This pressure sensor is mounted to a steam pipe so that steam flows in the tube 1 from the inflow port 3A and, when a light pulse is sent to the strand 2 from the light pulse tester provided to one end of the strand 2, the tube 1 expands in such a case that steam pressure becomes abnormally high and the curvature of the strand 2 becomes large and the transmission loss of the light pulse increases and abnormality is detected by the light pulse tester.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a pressure sensor, and particularly to a pressure sensor that can accurately detect pressure changes without using a power source by using optical fiber wires. It is.

[Conventional technology]

Conventionally used pressure sensors include the following:

+11 Bourdon tube pressure sensor that introduces fluid into a semicircularly curved pressure receiving pipe to deform the curvature of the pressure receiving pipe, and detects changes in fluid pressure based on the amount of deformation (2) The diaphragm is deformed by the pressure of the fluid Diaphragm pressure sensor (3) that detects changes in fluid pressure based on the amount of deformation.A bellows is placed inside a casing, fluid is introduced into the casing to deform the bellows, and changes in fluid pressure are detected based on this amount of deformation. Bellows-type pressure sensor (4) Capacitance-type pressure sensor that changes the gap between electrode plates depending on the pressure and electrically detects changes in fluid pressure based on the amount of change (5) Capacitance-type pressure sensor that uses semiconductors to measure fluid pressure Semiconductor Sensor for Electrical Detection [Problem to be Solved by the Invention] However, the above-mentioned conventional pressure sensor has the following problems.

That is, since the pressure sensors (1) to (3) do not themselves have a pressure transmission function, for example, when these sensors are used for remote monitoring of gas leaks from natural gas pipelines, pressure Equipment costs are high because a separate transmission line is required.

On the other hand, the pressure sensors (4) and (5) above require a power source, so although they themselves have a pressure transmission function, they require incidental equipment such as a power cord and an amplifier.
Equipment costs still apply.

Therefore, an object of the present invention is to provide a pressure sensor that can accurately detect changes in fluid pressure without requiring a separate pressure transmission path or power source.

[Means to solve the problem]

The present invention provides a flexible tube, an optical fiber strand embedded in the wall of the tube in the axial direction thereof, and a tube for fixing both ends of the tube.
The casing has a fluid inlet communicating with the tube at one end and is closed at the other end, and a restraining ring provided at the center of the casing for restraining the expansion of the tube. It has the following.

Next, one embodiment of the pressure sensor of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view showing one embodiment of the pressure sensor of the present invention.

As shown in FIG. 1, the pressure sensor of the present invention includes a flexible tube l made of rubber or the like, an optical fiber strand 2 embedded in the wall of the tube l in the axial direction, and a tube l. It consists of a casing 3 for fixing both ends of the tube 1 and a restraining ring 4 provided at the center of the casing 3 for restraining the expansion of the tube 1.

The casing 3 is assembled by bolts 5, has a fluid inlet 3^ communicating with the tube 1 at one end, and is closed at the other end by a blind plate 6.

As the optical fiber wire 2, a conventionally known one is used. The reason why the optical fiber strand 2 is embedded in the tube 1 is to prevent the optical fiber strand 2 from being damaged by fluid.

This invention proposes that the transmission loss of the optical fiber element [2 changes depending on its curvature, that is, the transmission loss of the optical fiber element [2] changes according to its curvature.
The transmission loss increases as the curvature of the optical fiber 2 increases, which is a unique characteristic of the optical fiber 2. The change in the curvature of the optical fiber strand 2 is
This becomes more noticeable with the restraining ring 4.

According to the pressure sensor of the present invention configured as described above, the pressure of the fluid is detected in the following manner.

For example, the pressure sensor is attached to a steam pipe in such a way that steam flows into the tube l from the fluid inlet 3^ of the casing 3. Then, an optical pulse is sent to the optical fiber strand 2 from an optical pulse tester provided at one end of the optical fiber strand 2, and the transmission loss of the optical pulse is measured by the optical pulse tester. At this time, when the steam pressure in the steam pipe is normal, the optical fiber element! The optical pulse tester is adjusted in advance so that the transmission loss of the optical pulse transmitted through the optical pulse tester 2 is zero.

When the steam pressure in the steam pipe becomes abnormally high, the tube 1 expands. When the tube 1 swells, the curvature of the optical fiber 2 attached thereto increases, and the transmission loss of optical pulses increases.

A change in the transmission loss of this light pulse is detected by a light pulse tester, and an abnormality in the vapor pressure within the steam vibrator is detected.

〔Effect of the invention〕

As explained above, the pressure sensor of the present invention has both a sensor function and a transmission path, so it is useful in that it can accurately detect changes in fluid pressure without requiring a separate signal cable or power source. effect is brought about.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing one embodiment of the pressure sensor of the present invention. In the drawings, 1-tube, 2-optical fiber wire, 3-casing, 4-restraint ring, 5-bolt, 6-blind plate.

Claims (1)

[Claims] (1) A flexible tube, an optical fiber strand embedded in the wall of the tube along its axial direction, and a fluid inlet communicating with the tube at one end for fixing both ends of the tube. 1. A pressure sensor comprising: a casing having a closed end; and a restraining ring provided at the center of the casing for restraining expansion of the tube.