JP2742606B2 - Road heating control method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a road heating control method for melting snow on a road surface and for preventing water freezing on the road surface.

[Prior art] In recent years, the importance of roads has increased with the development of automobile traffic, and many roads have been constructed and maintained. Particularly in cold regions, the road surface freezes or snows in winter,
In many cases, the function is not sufficiently performed due to danger of running, impassability, and the like. Currently, snow melting on major roads,
As a method of snow removal, mechanical snow removal, snow melting by cold materials such as calcium chloride, snow melting by electric heating, snow melting by groundwater, etc. are carried out, and there are advantages and disadvantages in the effect and economy,
Snow melting by electric heat is often used at the entrances and exits of tunnels. This road heating system that melts snow by electric heating embeds a heating wire for heating in a meandering shape at a certain depth from the road pavement surface, conducts electricity to this heating wire and transmits heat to the surrounding pavement material, It prevents snow melting and freezing. In such a road heating system, automatic control of the road surface temperature is indispensable to save power consumption and management personnel.

Conventionally, as such an automatic control method, an unmanned measurement of the presence or absence of snowfall, the presence or absence of moisture on a road surface, and the like, a target road surface temperature is automatically calculated from the result, and the target temperature and the actual road surface There is generally known a method of controlling the energizing current so that the temperatures match. For example, if the road surface has moisture, a processing method is proposed in which the road surface temperature is maintained at a temperature equal to or higher than the freezing temperature, and when there is snowfall, the temperature is maintained at a higher temperature to obtain a snow melting effect. Have been. In addition, in order to ensure that a desired effect is obtained even on a road surface having a large heat capacity, the road surface is preheated to a slightly lower constant temperature even when there is no snowfall or when there is no moisture on the road surface. In general, a preheating operation is also used. For example, the road surface temperature is set to -1 ° C. so that the road surface can quickly reach the snow melting and freezing prevention temperature of + 2 ° C. even if the weather conditions change rapidly.

[Problems to be Solved by the Invention] However, this conventional set temperature largely considers the influence of wind blowing on the road surface, and in some cases, the set temperature of -1 ° C is more than necessary. . In other words, when there is no wind or when the wind is not very strong, the air near the road surface stagnates in almost the same place, and as a result, the air is heated up to the road surface temperature, so that the heat dissipation from the road surface is kept low. In other words, while the heat insulation layer is formed, the air near the road surface is blown off during strong winds and the heat insulation layer is not formed, so heat is constantly dissipated from the road surface and the apparent current input effect is remarkable. Will decrease. Further, when moisture exists on the road surface, the moisture is vaporized by the strong wind, and the heat of vaporization of the road surface is deprived. Therefore, the heat dissipation is further increased. The effects of these heat dissipations are most fatally apparent when switching from the preheating operation state to the snow melting or freezing prevention state.

That is, when the wind speed is relatively small for the above-mentioned reason, as shown by the curve A in FIG. 4, for example, the preheat temperature reaches the target temperature + 2 ° C. in 3 hours even when the preheat temperature is from −3 ° C. If the preheating temperature is -3 ° C,
As shown by the curve B, the target temperature will not be reached even after the elapse of the predetermined three hours, and there is a possibility that running snow and impassability may occur due to the snow and freezing generated during this time. Therefore, conventionally, the preheating temperature of the road surface is set to, for example,-
Although set at 1 ° C., there is a problem that the amount of current for preheating becomes unnecessarily large when there is no wind.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a road heating control method capable of accurately performing road surface temperature control with a necessary minimum amount of current.

[Means for Solving the Problems] In order to achieve the above object, in the road heating control method according to the present invention, when the road surface temperature is preheat-controlled by a heating wire buried under the road surface, the temperature is controlled. The road surface temperature, road surface moisture, snowfall conditions and wind speed near the road surface to be measured are measured, and the target temperature is determined from the measured values including at least the wind speed, and the heating wire is set so that the road surface temperature matches the target temperature. The method is characterized in that the amount of heat generated is controlled.

[Operation] The road heating control method having the above configuration includes:
The road surface temperature is controlled by using the wind speed near the road surface to determine the target road surface temperature, and the rise in actual snowfall or switching to the anti-icing state is fast while securing the required minimum source current.

[Embodiment] The present invention will be described in detail based on the embodiment shown in Figs.

FIG. 1 shows a control block diagram for realizing a road heating control method according to the present invention, in which a heating line HT buried at a certain depth from a road pavement surface (not shown) is provided at a predetermined power supply voltage. One unit is long enough to generate sufficient Joule heat, and usually a plurality of units are connected in parallel and a power control element such as a triac
It is connected to the heater electric power source S via TR. A control output of the control computer 2 is connected to a control terminal G of the power control element TR via a D / A converter 1. The control computer 2 is connected to road surface temperature measuring means 4 such as a radiation thermometer via a converter 3, an anemometer 6 via an A / D converter 5, a snowfall sensor 7 and a moisture meter 8. In addition, the moisture meter 8 has a moisture electrode 9 installed on the road surface.
Is connected.

In the above-described configuration, the anemometer 6 measures the wind speed at the installation location of the system, and the A / D converter 5 converts the measured value to A / D and gives it to the control computer 2. Are integrated for a certain period of time to obtain an average wind speed, and a process of using this as a wind speed value at each time is performed. The snowfall sensor 7 detects the presence or absence of snowfall, and outputs a high-level signal when snowfall occurs, for example.
At the time of no snowfall, a low level signal is given to the control computer 2. Further, the moisture meter 8 is provided with a moisture electrode 9 based on the moisture content of the road surface.
Has a function of giving a high level signal to the control computer 2 when moisture is present on the road surface and a low level signal when the road surface is dry, for example, by utilizing the fact that the inter-electrode resistance changes. ing.

The control computer 2 calculates the target road surface temperature from the data of the average wind speed, the presence or absence of snowfall, and the presence or absence of road surface moisture based on the control method as exemplified in the flowchart shown in FIG. Determine the value. At the time of the control operation, the target value of the road surface temperature is further compared with the actual measured value of the road surface temperature measured by the road surface temperature measuring means 4 and converted into the temperature data by the converter 3, so that the actual road surface temperature approaches the target value. The control output is given to the control terminal G via the D / A converter 1.

In the example shown in FIG. 2 as a processing method for determining the target value, first, the condition of the road surface is determined from the detection results of snowfall and the presence or absence of road surface moisture. That is, no snowfall is detected,
If no moisture on the road surface is detected, the road surface is determined to be dry. When the road surface moisture is detected, it is determined that the road surface is wet regardless of the presence or absence of snowfall. Further, when snowfall is detected but moisture on the road surface is not detected, it means that the snow that has fallen remains on the road surface without being melted, and thus the road surface is determined to be in a snow-covered state. Therefore, in this road heating system, the preheating operation, the antifreezing operation, and the snow melting operation may be performed in each case.

Next, the road surface at the target temperature during each operation is finely determined based on the average wind speed data. In other words, during the preheating operation, for example, at a low wind of an average wind speed of less than 2 meters per second, -3 ° C. at a moderate wind speed of 2 meters per second or more and less than 4 meters per second, −2 ° C. at a strong wind of 4 meters per second or more. The target road surface temperature is determined at 1 ° C. In this way, even when the target road surface temperature is switched from the preheating operation to the snow melting or freezing prevention state of, for example, + 2 ° C., at the time of the weak wind shown by the curve A ′ and the strong wind shown by the curve B ′ as shown in FIG. In either case, it becomes possible to reach the target temperature of, for example, + 2 ° C. in a predetermined time of, for example, 3 hours.

In the anti-freezing operation, for example, +1
° C. The target road surface temperature is determined to be + 2 ° C. at moderate and strong winds. By doing so, it is possible to prevent loss of the freezing prevention effect even when heat is dissipated due to evaporation of road surface moisture due to wind.

On the other hand, during the snow melting operation, when it is considered that the influence of the wind speed is particularly small, the target road surface temperature can be set to, for example, + 2 ° C. regardless of the wind speed, and the control algorithm can be simplified.

Note that the numerical values exemplified above are not inevitable, but are affected by the material of the road surface, the calorific value of the heating wire HT, the installation conditions of the system, the climate of the installation area, etc. Of course, it should be set appropriately.

Further, in the embodiment, the radiation thermometer is used for measuring the road surface temperature. However, any other measurement method may be used as long as the accuracy can be sufficiently maintained. When a radiation thermometer is used, care must be taken not to erroneously measure the temperature of an object that is higher than the road surface, such as a running automobile, as a measured value. For this purpose, a measurement point may be set at a position where there is no possibility of traffic such as a vehicle, or a temporary fluctuation in measured values may be removed via a low-pass filter.

[Effect of the Invention] As described above, the road heating measurement method according to the present invention uses the wind speed near the road surface to determine the target road surface temperature, thereby reducing the influence of heat dissipation from the road surface due to wind, Switching to the state of preventing snow melting and freezing can be realized with the minimum necessary current.

[Brief description of the drawings]

1 to 3 show an embodiment of a road heating control method according to the present invention. FIG. 1 is a control block diagram, FIG. 2 is a flowchart diagram, and FIG. 3 is a graph diagram of an example of temperature control. FIG. 4 is a graph showing an example of temperature control by a conventional road heating control method. HT is a heating wire, TR is a power control element, 1, 5 is an A / D converter, 2 is a control computer, 4 is a road surface temperature measuring means, 6
Is an anemometer, 7 is a snowfall sensor, 8 is a moisture meter, and 9 is a moisture electrode.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Katsumi Osumi, 4-1-1 Kita-Nijo-Nishi, Chuo-ku, Sapporo-shi, Hokkaido Inside Mitsubishi Cable Industries, Ltd. Hokkaido Branch (72) Masao Sakairi, Kita-Nijo-Nishi, Chuo-ku, Sapporo, Hokkaido 4-chome No.1 Mitsubishi Cable Industry Co., Ltd. Hokkaido Branch

Claims (1)

(57) [Claims] When the road surface temperature is preheat-controlled by a heating wire buried under the road surface, the road surface temperature, the road surface moisture, the snowfall condition and the wind speed near the road surface to be temperature-controlled are measured, and at least one of these is measured. A road heating control method, comprising: determining a target temperature from a measured value including a wind speed; and controlling a heat generation amount of the heating wire so that a road surface temperature matches the target temperature.