JPH02195219A - Sensor part of optical fiber temperature sensor - Google Patents

Abstract

PURPOSE:To make it possible to measure the temperature of a small spot-shaped part simply and accurately by tightly winding a part of a long fiber, and using the part as a sensor part. CONSTITUTION:One or more sensor parts are arranged and formed at arbitrary positions of a piece of a sensor fiber 2 at a suitable interval. The sensor parts are attached to small spot shaped temperature measuring parts. Thus temperature is measured. The sensor fiber 2 other than the sensor parts is provided along another body whose temperature is measured. Then the temperature distribution of the body whose temperature is measured can be measured. For example, the sensor part is mounted on the bearing of the rotary shaft of an electric motor. The remaining sensor fiber 2 is arranged along the electric wirings of the electric motor. Then, the temperature of the bearing itself and the temperature distribution of the electric wirings are measured at the same time. When the sensor part is mounted in an oil tank and the remaining sensor fiber 2 is arranged along an oil pipe, the temperature in the oil tank and the temperature of the oil pipe can be measured at the same time.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a sensor section of a distributed optical fiber temperature sensor using an optical fiber, and is capable of easily and accurately measuring the temperature of a small dot-shaped portion. This is what I did.

[Conventional technology]

Distributed optical fiber temperature sensors are currently being widely studied because they can detect the temperature distribution in the longitudinal direction of a single sensor fiber.

Such optical fiber temperature sensors, therefore, when applied to temperature measurement of long structures, for example,
It is possible to measure the temperature at multiple locations in a structure simultaneously with a single sensor fiber, which has a great advantage.

[Problem to be solved by the invention]

However, there is a problem in that this optical fiber temperature sensor is not necessarily suitable for accurately measuring the temperature of a specific small dot-shaped portion such as a structure.

[Means to solve the problem]

In this invention, the sensor part of the optical fiber temperature sensor is constructed by tightly winding a part of a long sensor fiber, thereby making it possible to accurately and easily measure the temperature of a small dot-shaped part. did·.

〔Example〕

FIG. 1 shows an example of a sensor section of an optical fiber temperature sensor of the present invention, and reference numeral 1 in the figure is a bobbin. The bobbin 1 is made of a material with a low coefficient of thermal expansion, such as carbon fiber reinforced plastic filled with aluminum oxide powder, glass, or ceramics. A sensor fiber 2 is wound around the outer peripheral surface of the bobbin l. The sensor fiber 2 converts the temperature change into an amplitude change, a phase change, and a phase change of the guided light.
It detects changes in the plane of polarization, etc., and single-mode or multi-mode silica-based optical fibers are used, and the optical fibers may be open twisted, bare wire, or cored wire. This sensor fiber 2 is long and a part of it is attached to the bobbin.
The remaining parts are led out from the bobbin 1. The diameter of the winding of the sensor fiber 2 is usually about 30 to 100 mm, but care must be taken because if the winding diameter becomes too small, the bending loss of the sensor fiber 2 itself will increase. Further, the length of the winding of the sensor fiber 2 naturally varies depending on the size of the bobbin 1, the distance resolution of the detection device, etc., but is usually about 2 to 1 rom. Bobbin 1 of sensor fiber 2
The sensor fiber 2 may be fixed to the bobbin l by applying wax or adhesive to both ends of the wound portion or the entire wound portion of the sensor fiber 2, and is mechanically attached to the bobbin l. It can also be done by method.

Temperature can be measured by creating one or more such sensor parts arranged at appropriate intervals on a single long sensor fiber 2, and by attaching these sensor parts to small dot-shaped temperature measuring parts. Measurements can be taken. At this time, if the sensor fiber 2 other than the sensor section is arranged along with another temperature-measuring object, the temperature distribution of this temperature-measuring object can also be measured at the same time. For example, this sensor section is attached to the rotating shaft bearing of an electric motor, and the remaining sensor fiber 2 is connected to the electrical wiring of this electric motor.
If this is added, the temperature of the bearing itself and the temperature distribution of the electrical wiring can be measured at the same time. Furthermore, by installing the sensor section inside the oil tank and attaching the remaining sensor fiber to the oil pipe, the internal temperature of the oil tank and the temperature of the oil pipe can be measured simultaneously.

In the above embodiment, the sensor fiber 2 is wound and fixed around the bobbin 1, but the sensor fiber 2 is wound around the bobbin 1 and fixed, but
Only the sensor fiber 2 may be wound into an air-core coil shape that is fixed to each other, and this may be used as the sensor section.

[Experiment example]

Outer diameter 125μ11 Core diameter 50μ, relative refractive index difference 1゜0
% graded index type quartz optical fiber bare wire with silicone resin applied to make the outer diameter 400aR,
This was further coated with FEP (tetrafluoroethylene-hexafluoropropylene copolymer) resin to form a sensor fiber with an outer diameter of 0.9 x m.

This sensor fiber was wound around a ceramic bobbin having an outer diameter of 50I by a length of 5 m to form a sensor section, and two such sensor sections were created every 50 m of the sensor fiber. These sensor sections were attached to the bearings of two electric motors, and the remaining sensor fibers were attached to the outer surface of the electrical wiring of each electric motor. A Raman scattering type 0TDR device with a measurement accuracy of 0.5° C. and a distance resolution of 1 m was used as a detector.

As a result, we were able to measure the temperature of the motor bearing and the temperature distribution of the electrical wiring on par with conventional temperature sensors.

〔Effect of the invention〕

As explained above, the sensor part of the optical fiber temperature sensor of the present invention is made by tightly winding a part of a long sensor fiber, so it is easy to measure the temperature of a small dot-shaped part. In addition, it is possible to measure accurately, and to simultaneously measure the temperature of the dotted portion and the temperature distribution of other portions using the remaining sensor fiber.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an example of the sensor section of the optical fiber temperature sensor of the present invention. l...Bobbin, 2...Sensor fiber.

Claims (1)

[Claims] A sensor section of an optical fiber temperature sensor, characterized in that the sensor section is formed by tightly winding a part of a long sensor fiber.