JP4208199B2 - Road surface freezing prevention method and road surface sensor - Google Patents

Description

  Provide multiple simulated road surfaces of the same structure with the same surface heat radiation amount as the road surface to make a calorimeter, and supply heat by setting different temperatures to keep each surface temperature constant. In addition to determining the temperature of the fictitious calorimeter where the amount of heat to be supplied is zero in the extended curve obtained by graphing the relationship between temperature and heat based on the amount of heat per unit time, the actual road surface temperature can be measured by specific contact The amount of heat obtained by matching the measured value to the extension curve is measured as the total amount of heat supplied from the road surface including others under the roadbed, and the amount of heat necessary to prevent freezing is distributed and distributed on the road surface. The present invention relates to a method for determining the concentration of a cryoprotectant.

(Causes of slip accidents due to road surface freezing)
Most of slip accidents due to freezing occur at night, and the weather conditions at that time are often below freezing because the surface of the road surface falls below the temperature due to radiative cooling, especially the bridge part can not receive heat supply from the roadbed. The temperature is more likely to drop than the road surface with the roadbed. Even in the road surface with a roadbed, the shaded surface that is not easily affected by solar heat during the day has a lower surface temperature than the air temperature, and the same phenomenon as the bridge portion occurs.

  When the road surface temperature is lower than the air temperature, when the road temperature is 0 ° C. or higher, moisture in the air adheres to a dew condensation state, and when the road surface is below freezing, frost forms. When the moisture condensed on the asphalt surface freezes, the road surface freezes in the same black color as the asphalt, so it is difficult for the driver to recognize freezing, and road officials are afraid of black ice.

  When frost adheres to the road surface, the road surface becomes white, so it is easy for the driver to recognize that it is easy to slip because it is mistaken for snow, but there are factors that impede the constant linear motion of the vehicle due to curves and brake operations etc. And a posterior due to slip occurs. In addition, when water is artificially sprayed on the road surface by watering snow melting or the like, the water remaining on the road surface after freezing water freezes and becomes a black ice state.

  In addition, the snow covered road surface becomes easy to slip because of the sun's radiant heat and positive temperature during daytime, and if the water on the snow surface freezes due to radiative cooling at night, etc., it becomes a frozen frozen road surface and a slip accident is likely to occur. . Conventionally, as a method for preventing such freezing, a facility for applying heat to the road surface is provided, or an antifreezing agent is distributed.

(Problems with current technology that prevents freezing by applying heat to the road surface)
The method to prevent freezing by applying heat to the road surface is generally heated by a heater embedded about 10 cm below the surface of the road surface, and the temperature of the road surface is about 7-10 ° C. with a temperature sensor embedded at the same depth. Controlled to keep. In many cases, equipment for preventing freezing by applying heat is applied in the range of about 150 to 250 W per 1 m ² in terms of electric heat.

  In these facilities, in order to keep the temperature below the road surface constant, heat is supplied regardless of the amount of heat released from the road surface due to weather fluctuations, and it takes a long time for the surface temperature to rise more than necessary. Is given to. In addition, when the amount of heat released from the road surface exceeds the supply amount, it cannot have a function of determining the situation where the surface temperature is below freezing point, and therefore there is a problem that it cannot be determined even if it becomes slippery due to freezing.

  As an existing technology for solving these problems, there is "Integrated device for continuous measurement and control of snow melting and anti-freezing heat and anti-freezing control method" according to Japanese Patent No. 2840919. Therefore, it is necessary to set the temperature at which freezing is measured to about 1 ° C below the freezing point where the snow cannot be melted. Furthermore, since the actual road surface temperature is not measured, it can be said that the relationship between the actual road surface and the calorimeter is ignored. In addition, the calorific value necessary for anti-freezing by this method is a value including the latent heat possessed by the moisture on the road surface, and it can be said that the calorie is kept at 1 ° C. below the freezing point after freezing.

(Problems of current technology to prevent freezing by distributing anti-freezing agents)
The antifreezing method by spraying the antifreeze agent uses the freezing point depression of the aqueous solution in which the antifreeze agent stays on the road surface and depends on the solution concentration. For example, the freezing temperature of 10% calcium chloride solution is about minus. At 6 ° C and 15%, it is about minus 11 ° C, and at 20%, it is about minus 18 ° C.

  Also, spraying anti-freezing agent on the snowy road surface solves the snowy surface by freezing the snowy surface that is smooth and slippery to form a rough snow surface mixed with high concentration solution, and obtains braking friction in winter tires Is. On snowy surfaces, the temperature reached by all heat balance received by the road surface, including radiant cooling, temperature, and heat radiation from surrounding objects, is often lower than the air temperature. The rough surface of the snow surface is secured.

In determining the amount of antifreezing agent to be applied to the road surface without snow or on the snow surface, the conventional technology measures the surface temperature reached by all heat balance received by the road surface, including radiation cooling, temperature, and heat radiation from surrounding objects. Since it can not be done, it is in a state of distributing an antifreeze agent more than necessary. Solution By the way, sprayed judgment of anti-freezing agent is to rely on feeling of the people obtained in many years of experience, sprayed amount in the case are many, based on a state snow is not in the road surface that is going to guide the 1m ² per 30~50g Freezing is prevented with a target concentration of about 10%.
Patent No. 2840919 “Integrated device for continuous measurement and control of snowmelt melting heat quantity and freeze prevention heat quantity, and freeze prevention control method”

  In the method to prevent freezing by applying heat to the road surface, the surface reached by all the heat balance naturally received by the road surface including radiation cooling, temperature radiation, heat radiation from surrounding objects, and the amount of heat supplied from the roadbed There is a need for an ideal anti-freezing method that does not waste by calculating the amount of heat necessary to know the temperature and calculating the amount of heat required to maintain the road surface temperature at a temperature slightly higher than 0 ° C. that does not freeze.

  In addition, the conventional method of qualitatively distributing an antifreeze agent by relying on the feeling of people is that the road surface without snow or the snow road surface is supplied with radiation cooling, temperature / heat radiation from surrounding objects, and from the roadbed. Knowing the surface temperature reached by all the heat balance received by the road surface including the amount of heat generated, the concentration corresponding to that temperature can not be determined, sometimes distributed excessively, sometimes causing insufficient accidents Therefore, the present invention provides a freeze prevention method for solving these problems.

  In solving the two problems of the method of preventing freezing by applying heat to the road surface and the method of preventing freezing with the antifreeze agent distribution, a plurality of simulations manufactured with the same component configuration having the same surface heat radiation amount as the road surface Provide a road surface to create a calorimeter, set different temperatures to keep each surface temperature constant, supply heat, and graph the relationship between temperature and heat based on the amount of heat per unit time required for each The temperature of the fictitious calorimeter where the amount of heat to be supplied is zero is obtained in the extended curve obtained.

  Therefore, in the case of a method for preventing freezing by applying heat to the road surface, based on this extended curve obtained every measurement time, if the actual road surface temperature starts to fall below the target temperature, for example, 1.0 ° C, Control is performed to supply the heat amount that is insufficient to keep the temperature at 1.0 ° C corresponding to the extension curve. Therefore, it is possible to prevent freezing with a minimum amount of heat. On the other hand, in the case of the anti-freezing method using anti-freezing agent distribution, the temperature of the fictitious calorimeter where the heat obtained from the extension curve becomes zero approximates the minimum temperature of the road surface caused by the weather at that time. The solution concentration of the corresponding cryoprotectant can be determined. Therefore, the amount of the antifreezing agent can be reduced to the minimum necessary amount.

  FIG. 1 shows a configuration of a calorie measuring panel, which is composed of a simulated road surface material 1, a thermocouple 2, an electric heating element 3, and a heat insulating material 4. Fig. 2 shows the configuration of the sensor. The sensor has three calorimeters A, B, and C. Platinum that also serves as a reference temperature to be measured by the thermocouples of the calorimeters A, B, and C A temperature measuring device 5 using a temperature measuring body is provided, and a heat amount supply, a signal calculator 6 and a non-contact path thermometer 7 are integrated.

FIG. 3 is a graph showing the relationship between each calorific value and temperature in a graph obtained by converting the values measured by the calorimeters A, B, and C for 5 minutes into 1 m ² 1 minute units, and drawing an extension curve. The set temperature of calorimeter A is 1.1 kcal / m ² min at 1 ° C, B is 2.0 kcal / m ² min at 3 ° C, and C is 3.4 kcal / m ² min at 5 ° C. Therefore, connecting these three points and drawing an extension curve, the temperature at which the amount of heat becomes zero was determined to be about −3 ° C. The average temperature for 5 minutes when the calorific value was measured was -1 ° C, the average road surface temperature measured without contact was 2 ° C, and it was found from the extended curve that the road surface had a heat supply of about 1.5kcal / m ² minutes. Because the temperature is -1 ° C, which is lower than the road temperature, it can be seen that most of the heat is supplied from the roadbed.

By the way, in the anti-freezing equipment that applies heat to the road surface, assuming that the road surface temperature is set to 3 ° C, the insufficient heat amount is (2.0 kcal / m ² min)-(1.5 kcal / m ² min) = 0.5 kcal / It can be calculated as m ² minutes, and if this amount of heat is added by automatic control, it will be possible to maintain about 3 ° C, and the amount of heat naturally supplied from the roadbed can be used effectively.

  On the other hand, when the antifreeze agent is distributed, the temperature at which the heat value becomes zero is about −3 ° C. from the extension curve, so it is understood that the road temperature does not fall below −3 ° C. You can ask. By the way, the icing concentration at -3 ℃ of calcium chloride solution is about 6%.

A specific example of the configuration of the calorimeter. The sensor block diagram of this invention. An extension curve graph obtained by the calorimeter panel ABC.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Simulated road surface material 2 Thermocouple 3 Electric heating element 4 Heat insulation material 5 Temperature measuring device 6 Signal calculator 7 Non-contact road thermometer

Claims (3)

Provide a plurality of simulated road surfaces of the same structure with the same surface heat radiation amount as the road surface to make a calorimeter, set the calorimeters to different temperatures and supply heat to keep the surface temperature constant, Calculate the temperature of the fictitious calorimeter where the amount of heat supplied is zero in the extension curve obtained by graphing the relationship between temperature and heat amount based on the heat amount per unit time required for each, and calculate the actual road surface temperature. The amount of heat obtained by matching the value measured by contact with the extension curve is measured as the total amount of heat supplied from others including the underside of the road surface, and the insufficient amount of heat is supplied based on this. The road surface freeze prevention method. Provide a plurality of simulated road surfaces of the same structure with the same surface heat radiation amount as the road surface to make a calorimeter, set the calorimeters to different temperatures and supply heat to keep the surface temperature constant, Calculate the temperature of the fictitious calorimeter where the amount of heat to be supplied is zero in the extension curve obtained by graphing the relationship between temperature and heat amount based on the heat amount per unit time required for each, and the road surface reaches this temperature A road surface anti-freezing method characterized in that the concentration of an anti-freezing agent aqueous solution that does not freeze at this temperature is determined and distributed by setting the minimum temperature. In a road surface sensor that can measure the heat release amount of the road surface in a non-contact manner and determine the minimum temperature that the road surface reaches and the supply heat amount necessary for preventing the road surface from freezing, a plurality of calorimeters A, B, C,. The calorific value measuring panels A, B, C,... Are made of a simulated road surface material, a thermocouple, an electric heating element, and a heat insulating material, and a platinum temperature sensor that also serves as a reference temperature to be measured by a thermocouple is used. An air temperature measuring device is provided, and a heat supply and signal calculator, and a non-contact road thermometer are integrated, and the minimum temperature reached by the road surface is determined by each of the heat measuring panels A, B, C,. The amount of heat to be supplied in an extended curve obtained by graphing the relationship between temperature and heat amount based on the amount of heat per unit time required to set a different temperature and keep the surface temperature constant. It is calculated as the temperature of an imaginary calorimeter that becomes zero, and The amount of heat supplied to prevent road surface freezing is supplied by the road surface, including the underside of the roadbed, based on the actual road surface temperature measured by the non-contact road thermometer and corresponding to the extension curve. The road surface sensor is characterized in that it is measured as the total amount of heat and is calculated as a lack of heat based on this .

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