JPH0481152B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a road surface freezing prediction device that predicts road surface freezing in winter. Conventional technology As shown in Figure 3, conventional road surface freezing prediction devices measure only the road surface temperature, use a microcomputer to predict the time when the road surface temperature will reach 0°C from the change curve using a regression equation, and issue an alarm. A method was adopted to issue
57-74629). Problems to be Solved by the Invention However, when predicting road surface freezing on a sunny day in winter, the relative temperature is less than 100%, so the temperature at which moisture in the atmosphere condenses on the road surface is as shown in Figure 4.
It is lower than 0°C, so even if the road surface temperature reaches 0°C, there will be no condensation, and therefore the road surface will not freeze. For these reasons, road ice prediction warnings on sunny days in winter are unreliable, leading to drivers ignoring warnings and causing accidents. As described above, the conventional road surface freezing prediction device does not measure the dew point temperature of the atmosphere, and therefore cannot accurately predict freezing on a sunny day in winter. The present invention has been made in view of these points,
The present invention provides a road surface freezing prediction device that can accurately predict freezing by determining the atmospheric dew point temperature from the atmospheric temperature and relative temperature using a simple calculator. Means for Solving the Problems In order to solve the above problems, the road surface freezing prediction device of the present invention includes a road surface temperature signal output section that converts road surface temperature into an electrical signal, and a road surface temperature signal output section that converts atmospheric temperature and humidity into electrical signals. an atmospheric temperature and humidity signal output section;
A calculator that takes atmospheric temperature and humidity signals as input, calculates the dew point temperature of the atmosphere, and outputs a dew point temperature signal, and an alarm output device when the road surface temperature and the difference between the road surface temperature and the dew point temperature simultaneously fall below a predetermined temperature. This system outputs a road surface freezing prediction warning signal. Effects According to the present invention, the dew point temperature of the atmosphere is determined by the arithmetic unit and the difference between the road surface temperature and the dew point temperature is compared with the alarm setting value. To accurately predict road surface freezing on a sunny day. Embodiment FIG. 1 is a block diagram showing an embodiment of the road surface freezing prediction device of the present invention. In FIG. 1, 1 is a road surface temperature signal output unit that converts road surface temperature into an electrical signal, 2 is an atmospheric temperature and humidity signal output unit that converts atmospheric temperature and humidity into an electrical signal, and 3 is an atmospheric dew point temperature calculator. The voltage signals at the two input terminals 31 and 32 are operated to obtain a dew point temperature signal output at the output terminal 33. 4
is a comparator and turns ON- according to the voltage value of input terminal 42.
An OFF signal output is obtained from the output terminal 42. 5 is a comparator that responds to the voltage difference between the two input terminals 51 and 52.
An ON-OFF signal output is obtained from the output terminal 53. 6
is a condition discriminator, which consists of a 2-input AND circuit. 7 is a freezing prediction signal output section. In the above configuration, the road surface temperature t _B is converted into an electrical signal by the temperature signal output section 1 . On the other hand, the atmospheric temperature t _A and humidity H _A are changed into electrical signals by the temperature/humidity signal output section 2, and are further input to the input terminals 31 and 32 of the computing unit 3 and converted into electrical signals of the atmospheric dew point temperature t _d. be done. The road surface temperature signal and atmospheric dew point temperature signal thus obtained are input to the next stage comparators 4 and 5 and converted into ON-OFF signals.
That is, the road surface temperature signal is input to the comparator 4, and if it is below a predetermined temperature (A° C.), it is converted into an ON signal, and if it is above a predetermined temperature, it is converted into an OFF signal. Furthermore, the road surface temperature signal is input to the comparator 5 along with the atmospheric dew point temperature t _d from the respective input terminals 51 and 52, and when the potential difference between the road surface temperature signal and the atmospheric dew point temperature signal is equal to or less than the potential difference corresponding to a predetermined temperature difference (B deg), if there is
If it is above, it is converted to an OFF signal. The output signals of the comparators 4 and 5 are input to the condition discriminator 6, and when the conditions of the comparators 4 and 5 are satisfied at the same time, they are converted to an ON signal and a freezing prediction signal is output from the signal output section 7. That is, when the road surface temperature t _B is below A°C and the difference between the road surface temperature t _B and the atmospheric dew point temperature t _d (t _B - t _d ) is below B deg, the road surface freezing prediction signal is output from the signal output section 7. be done. Next, other embodiments of the present invention will be described. By the way, it is known that the dew point temperature t _d can be approximately expressed by the following formula. That is, t _d =a(t+p)(+q)+r...(1) where, t: dry bulb temperature: relative humidity a, p, q, r: constants. Now, define the constants a, p, q, and r as follows, and -
The dew point temperature is determined from (1) in the range of 15t<15℃, 70100%, and the difference between it and the dew point temperature t _dp determined from the international equation of state for saturated vapor pressure is as shown in the table.
It can be seen that approximation is possible at 0.3°C or less. a=1.305×10 ^-3 p=123.01 q=668.71 r=-123.01

【table】

[Table] Therefore, using equation (1), the calculator for the atmospheric dew point temperature is the product of the electrical signal expressed as a linear function of atmospheric temperature and the electrical signal expressed as a linear function of atmospheric relative humidity. It is possible to create an arithmetic unit consisting of an adder with a constant signal and an adder, and outputs the dew point temperature t _d of the atmosphere as a signal. FIG. 2 shows another embodiment of the invention. In the figure, 2 is an atmospheric temperature and humidity signal output section, and 201 is a temperature sensor consisting of a resistor 202 that detects a change in humidity as a change in resistance. The voltage value of the terminal 203 is a value obtained by dividing the voltage applied to the terminal 204 by the ratio of the humidity sensor 201 and the resistor 205, which constitutes a linear function of relative humidity, and becomes a humidity signal output. A temperature sensor 206 includes a thermistor 205 that detects temperature change as a resistance change. The thermistor 205 has a large B constant and constitutes an atmospheric temperature signal output section expressed by a linear function with temperature as a variable. 3 is an atmospheric dew point temperature calculation unit, which is connected to the inverting input terminal of the operational amplifier 301;
When the voltage of the terminal 203 is input, the resistor 302
A voltage is output to the terminal 304 according to the degree of amplification determined by the temperature sensor 206 and the temperature sensor 206 . Here, the output voltage of the terminal 304 is multiplied by a linear function with relative humidity as a variable and a linear function with temperature as a variable. Further, by using the operational amplifier 305 as an adder and adding the voltage at the terminal 304 and the voltage at the terminal 306, a voltage signal output at the dew point temperature is obtained at the terminal 307. By subjecting this dew point temperature signal to signal processing in the same manner as in the embodiment described above, the signal output section 7 outputs a road surface freezing prediction signal. Effects of the Invention As described above, according to the present invention, the dew point temperature of the atmosphere can be determined from the atmospheric temperature and relative humidity using a very simple calculator, and the freezing temperature of the road surface on a clear day in winter can be predicted and accurately. Freeze prediction and warning are possible, and the effect is great.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a road surface freeze prediction device according to an embodiment of the present invention, FIG. 2 is a block diagram showing a road surface freeze prediction device according to another embodiment of the present invention, and FIG. 3 is a block diagram showing a road surface freeze prediction device according to another embodiment of the present invention. FIG. 4, which is an explanatory diagram of the operation of the apparatus, is a diagram showing the relationship between dry bulb temperature and dew point temperature. 1... Road surface temperature signal output section, 2... Atmospheric temperature/humidity signal output section, 3... Arithmetic unit, 7... Signal output section.

Claims (1)

[Scope of Claims] 1. A road surface temperature signal output section that converts road surface temperature into an electrical signal, an atmospheric temperature and humidity signal output section that converts atmospheric temperature and humidity into electrical signals, and an input of atmospheric temperature and humidity signals. A calculator that calculates the dew point temperature of the atmosphere and outputs the dew point temperature as a signal, and outputs a freezing prediction alarm when the road surface temperature and the difference between the road surface temperature and the atmospheric dew point temperature simultaneously fall below a predetermined temperature. A road surface freezing prediction device consisting of an output device. 2. The road surface freezing prediction device according to claim 1, wherein the road surface temperature signal output section is composed of a plurality of temperature detectors, and the minimum value thereof is the road surface temperature. 3 The computing unit outputs a relative humidity signal voltage expressed by a linear function with atmospheric relative humidity as a variable, and a temperature signal output which changes the amplification degree by a resistance expressed by a linear function with atmospheric temperature as a variable. 2. A road surface freezing prediction device according to claim 1, which comprises a multiplier.