JP2700827B2 - Road surface temperature distribution measurement device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for heating and heating a road surface in order to melt snow on the road surface or to prevent freezing of water or snow on the road surface. The present invention relates to a device for detecting

2. Description of the Related Art In a cold region, it is extremely important to melt snow on a road surface or to prevent freezing in order to secure road traffic in winter. In recent years, attempts have been made to prevent snow melting and freezing by heating the road surface by various heating means.

By the way, simply heating the road surface blindly to prevent snow melting and freezing on the road surface results in poor energy use efficiency and enormous energy costs. Therefore, in order to increase energy use efficiency and reduce costs, road surface temperature and outside air temperature are detected, and the heating means is controlled in accordance with the detected temperature to provide the minimum heat energy necessary to prevent snow melting and freezing. It is essential. Conventionally, as a sensor for detecting the road surface temperature for such a purpose, use of a thermocouple, various resistance temperature detectors, and a semiconductor sensor represented by a thermistor has been considered.

Problems to be Solved by the Invention The temperature of the road surface, particularly the temperature of the road surface in the presence of snow,
The temperature distribution is usually not uniform due to subtle effects of snow drifts and building shadows. Therefore, in order to truly prevent snow melting and freezing on the road surface, instead of detecting the temperature at only one point, the temperature is detected linearly or in a planar manner, the temperature distribution is detected, and heating is performed according to the temperature distribution. It is desirable to control the means.

However, thermocouples, resistance temperature detectors, semiconductor sensors, and the like, which are conventionally considered to be used for detecting the road surface temperature, can detect only one temperature. Therefore, if temperature detection is to be performed at multiple points in order to detect the temperature distribution, a large number of sensors will be required, resulting in increased costs and significantly complicated detection wiring, making maintenance and inspection difficult. Occurs.

The present invention has been made in view of the above circumstances,
When heating the road surface to prevent snow melting and freezing on the road surface, the linear or planar distribution of the road surface temperature can be detected easily and easily, resulting in a significant increase in costs and complicated maintenance. It is an object of the present invention to efficiently control the surface heating without causing the problem, and to be able to simultaneously measure both the temperature distribution on the road surface and the outside air temperature.

Means for Solving the Problems In order to solve the above problems, the present invention uses a Raman scattering type distributed temperature sensor as a sensor for detecting the road surface temperature.

Specifically, in the road surface temperature distribution measuring device of the present invention, an optical fiber, which is a temperature detecting portion of a Raman scattering type distributed temperature sensor, is inserted into a hollow tube, and the hollow tube is inserted into a surface layer of a road surface. And a part of the hollow tube body into which the optical fiber is inserted and a part of the optical fiber itself are exposed to the outside air atmosphere.

Further, in the road surface temperature distribution measuring device of the present invention, it is desirable that the hollow tube body into which the optical fiber is inserted is buried in a meandering shape in the surface layer of the road surface.

Further, in the road surface temperature distribution measuring device of the present invention, the hollow tube may be filled with a substance for transferring heat between the hollow tube and the optical fiber.

The Raman scattering type distributed temperature sensor can measure the temperature distribution in the length direction of the optical fiber which is the temperature detecting part. The principle of measuring the temperature distribution by such a Raman scattering type distributed temperature sensor is as follows.

That is, when light is incident on the optical fiber, slight fluctuations in the refractive index within the optical fiber and light scattering due to absorption by molecules and atoms constituting the optical fiber and re-emission occur. The scattered light includes Rayleigh scattered light having the same wavelength as the incident light and Raman scattered light having a different wavelength from the incident light. The latter Raman scattered light is scattered light generated by thermal vibration of molecules and atoms constituting the optical fiber, and the intensity thereof largely depends on temperature. Therefore, pulsed light of a specific wavelength (usually a laser pulse) is used as the incident light, and the delay in the time until the light returns due to the scattered light and the intensity of the Raman backscattered light are detected. The temperature at each position in the vertical direction can be measured.

Therefore, if the optical fiber, which is the temperature detecting portion of such a Raman scattered light distribution type temperature sensor, is buried in the surface layer of the road surface of the road, the temperature distribution on the road surface can be measured.

Here, if the optical fiber is buried as it is, it is extremely weak against mechanical stress from the road surface, but by inserting it into a hollow tube and burying it in the surface layer of the road surface, the optical fiber Can be protected mechanically.

Also, here, in the road surface temperature distribution measuring device of the present invention,
Because part of the hollow tube body into which the optical fiber is inserted, or part of the optical fiber itself is exposed to the outside atmosphere,
In that portion, the outside air temperature is measured, and therefore, it is possible to simultaneously measure both the road surface temperature distribution and the outside air temperature.

If the hollow tube into which the optical fiber is inserted is buried in a meandering shape, the temperature distribution on the road surface can be measured in a planar manner.

If the inside of the hollow tube is filled with a substance that conducts heat between the hollow tube and the optical fiber, the response of temperature measurement can be improved.

Embodiment FIGS. 1 and 2 each show an example of a configuration in which an optical fiber 1 as a temperature detecting unit in a device according to the present invention is inserted into a hollow tubular body 2. FIG.

In the example shown in FIG. 1, the optical fiber 1 is inserted into a hollow tubular body 2 made of plastic such as hard polyethylene resin. This example is suitable for embedding on a road surface at a location where mechanical stress is relatively small, for example, on a sidewalk.

In the example shown in FIG. 2, the optical fiber 1 is inserted into a hollow tube 2 formed by forming a sheath 2B of hard polyethylene resin or rubber on the outer periphery of a corrugated tube 2A made of metal such as aluminum alloy or steel. Have been. This example is suitable for embedding on a road surface where mechanical stress is large, for example, on a road.

In the examples shown in FIGS. 1 and 2, one optical fiber 1 is inserted into the hollow tubular body 2. However, in some cases, two or more optical fibers are inserted by accommodating a spacer. Can also. Further, not only the optical fiber as the temperature detecting unit but also other optical fibers and signal lines for signal transmission can be inserted into the same hollow tube. In addition, a liquid such as water or antifreeze, a gas such as H ₂ or He, or a metal powder must be filled between the hollow tube and the optical fiber as a material for conducting heat. It is desirable to improve the heat conduction from the hollow tube to the optical fiber, thereby improving the responsiveness of the temperature measurement.

The hollow tube body 2 into which the optical fiber 1 is inserted as described above,
For example, as shown in FIGS. 3 and 4, it is embedded in the surface layer 4 of the road surface 3 so that its length direction is parallel to the road surface.

In FIG. 4, an alfalt pavement layer, for example, is provided as a surface layer 4 on a roadbed 5 of a road, and the above-described optical fiber insertion hollow tubular body 2 is embedded in the alfalt pavement layer 4. And this optical fiber inserted hollow tube 2
Is arranged so as to meander along the length direction A of the road as shown in FIG. 3, and the terminal of the optical fiber 1 is connected to the measuring unit 7 via the optical coupler 6.

In FIGS. 3 and 4, a part 21 of the hollow optical fiber tube 2 is connected to the road surface 3 on the front side of the asphalt pavement layer 4.
Exposed above. That is, this portion 21 is exposed to the outside air atmosphere.

The above-described measuring unit 7 is for giving laser pulse light as incident light to the optical fiber 1, separating Raman backscattered light returning from the optical fiber 1, receiving the amplified light, and amplifying and averaging it. For example, as shown in FIG. 4, a laser light source 8 for oscillating laser pulse light as incident light, a laser driving circuit 9 for driving the laser light source 8, and a return from the optical fiber 1. Separation duplexer 10 for separating Raman scattered light from reflected scattered light
And, a separation duplexer 10 for separating Raman scattered light,
A cut duplexer 11 for cutting light components other than the Raman light in the Raman scattered light, and a light receiving device for receiving the Raman scattered light output from the cut duplexer 11 and converting it into an electric signal It comprises an element 12, an amplifier 13 for amplifying an electric signal from the light receiving element 12, and an averaging circuit 14 for improving the S / N ratio of the electric signal. The output signal of the measuring section 7 (the output signal of the averaging circuit 14) is provided to the host computer 15, and a signal for control from the host computer 15 is provided to the measuring section 7. The host computer 15 calculates the temperature distribution in the length direction of the optical fiber 1 by performing arithmetic processing on the electric signal from the measuring section 7.

The calculated temperature distribution may be simply displayed and / or recorded in the display / recording unit 16,
Usually, the signal of the temperature distribution is used as a signal for controlling the snow melting device 18 for heating the road surface and melting the snow. That is, the snow melting device 18 is constituted by, for example, an electric heater or a hot water pipe for flowing hot water from a hot water boiler, and the controller 19 for controlling the heating output in the snow melting device 18 sends the data from the host computer 15 to the controller 19. The temperature distribution signal is input, and the snow melting device according to the temperature distribution
18 heating outputs are controlled.

Here, the mode of controlling the heating output in the snow melting device 18 is arbitrary.For example, the road surface of the road is divided into blocks, and the heating output of the snow melting device in each block is individually corresponding to the measured temperature distribution. It is desirable to control it. By performing such control, it is possible to efficiently perform snow melting with the minimum necessary energy. In some cases, the heating output of the snow melting device may be controlled based on the average value of the temperature distribution.

Since a part of the hollow tube into which the optical fiber is inserted is exposed to the outside air, Raman scattered light from that part corresponds to the outside air temperature, and thus the outside air temperature and the road surface temperature distribution. Can be measured simultaneously. In this case, the signal from the host computer 15 includes both the road surface temperature distribution signal and the outside air temperature signal, and the heating output control of the snow melting apparatus can be performed more easily and efficiently.

In the above-described example, a part of the hollow tube into which the optical fiber is inserted is exposed to the outside atmosphere, but in some cases, a part of the optical fiber itself may be exposed to the outside atmosphere,
In this case as well, the external device temperature and the road surface temperature distribution can be simultaneously measured as described above.

As described above, as a method for inserting an optical fiber into a hollow tube as a protective tube, only the hollow tube is buried in advance in the surface layer of the road surface, and then the optical fiber is hollowed by an air blow method or the like. It is desirable to insert it into the tube. In some cases, an optical fiber may be inserted into a hollow pipe of an existing pipe buried for another purpose by an air blow method.

When the hollow tube into which the optical fiber is inserted is embedded in the meandering shape on the road surface as described above, the hollow tube may be embedded over both the road and the sidewalk. A hollow tube which is strong against mechanical stress as shown in the figure is used, and a hollow tube which is relatively weak against mechanical stress as shown in FIG. It is desirable to use

According to the road surface temperature distribution measuring device of the present invention, a linear or planar temperature distribution on a road surface can be measured by using only one optical fiber as the temperature detecting unit.
Therefore, it is possible to reduce the energy cost by controlling the heat energy for heating the road surface to a necessary minimum appropriate amount to prevent snow melting and freezing. Further, according to the road surface temperature distribution measuring device of the present invention, a linear or planar temperature distribution can be measured without using a large number of sensors as in the case of using a conventional sensor. The effect is obtained that the cost is remarkably reduced as compared with the case where the sensor is used, and the wiring and the like are simplified, so that maintenance and inspection are facilitated. Further, in the road surface temperature distribution measuring device of the present invention, without using another temperature measuring device together,
Since not only the road surface temperature distribution but also the outside air temperature can be measured at the same time, the energy for heating the road surface can be efficiently controlled to an optimal amount according to the road surface temperature distribution and the outside air temperature.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 and 2 are longitudinal sectional views each showing an example of a state where an optical fiber is inserted into a hollow tube in a road surface temperature distribution measuring device of the present invention, and FIG. FIG. 4 is a schematic exploded view showing an example of the entire configuration of the road surface temperature distribution measuring device in plan view with respect to the road surface, and FIG. 4 is a longitudinal sectional view taken along line IV-IV in FIG. 1 ... optical fiber, 2 ... hollow tube.

Continuation of the front page (72) Inventor Tatsuya Sawuri 1-5-1, Kiba, Koto-ku, Tokyo Fujikura Electric Wire Co., Ltd. (56) References JP-A-64-32132 (JP, A)

Claims (3)

(57) [Claims] An optical fiber, which is a temperature detecting portion of a Raman scattering type distributed temperature sensor, is inserted into a hollow tube, the hollow tube is buried in a surface layer of a road surface, and an optical fiber is further inserted. A road surface temperature distribution measuring device, wherein a part of the hollow tube or a part of the optical fiber itself is exposed in an outside air atmosphere. 2. The road surface temperature distribution measuring device according to claim 1, wherein the hollow tube body into which the optical fiber is inserted is buried in a meandering shape in a surface layer of the road surface. 3. The road surface temperature distribution measuring device according to claim 1, wherein the hollow tube is filled with a substance for conducting heat between the hollow tube and the optical fiber.