JPH042918B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a road surface freezing warning device that detects a frozen state of a road surface and issues a warning. Conventional technology Conventional road surface freezing warning devices determine whether the road surface is frozen by detecting temperature such as road surface temperature or outside air temperature, or by detecting moisture on the road surface using microwaves, visible light, or infrared rays (Japanese Patent Application Laid-Open No. 59-1993). −18854). Problems to be Solved by the Invention However, when detecting road surface freezing based only on temperature information, the temperature on a bridge in winter can be about 3°C lower than the outside air temperature, and the atmospheric temperature is higher than the dew point and 0. Even if the temperature is above ℃, the surface of bridges may freeze in winter. For this reason, information regarding frozen bridge roads in winter is unreliable and is often ignored by drivers, sometimes resulting in accidents. Also, the temperature at which dew condenses changes depending on atmospheric pressure,
Until now, this had not been taken into account when determining whether roads were frozen, leading to errors in detecting frozen roads at high altitudes. Furthermore, when detecting road surface conditions using microwaves, visible light, or infrared rays, the device becomes large, which poses a problem for use in vehicles. The present invention takes the above-mentioned problems into consideration, and detects the dew point temperature of outside air corrected by atmospheric temperature information and atmospheric pressure, dramatically improving the reliability of information on frozen roads in various places, and making it suitable for use in vehicles. The present invention provides a road surface freezing warning device that is sufficiently small and lightweight. Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides a temperature signal output section and a humidity signal output section that are provided in a vehicle and convert the temperature and humidity of outside air into signals, and a signal output section that converts atmospheric pressure into signals. It uses an atmospheric pressure signal output section that converts the temperature signal, humidity signal, and atmospheric pressure signal of the outside air as input, and calculates the dew point temperature of the outside air considering the influence of changes in atmospheric pressure due to altitude. The present invention is constructed such that a determining section determines the frozen state of the road surface based on the signal, and a warning section outputs a road surface freezing warning signal when the determining section determines the frozen state of the road surface. Effects With the above configuration, the present invention calculates the dew point temperature of the outside air taking into account the influence of atmospheric pressure, and compares it with the outside air temperature to issue a road surface freezing warning. Freeze warning is now possible,
It is also possible to achieve smaller size and lighter weight. Embodiment An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. In Fig. 1, 1 is an outside air temperature signal output section that converts the outside air temperature (TO) into an electrical signal, 2 is an outside air humidity signal output section that converts the outside air humidity (Ho) into an electrical signal, and 3 is an atmospheric pressure (PO). ) is an atmospheric pressure signal output unit that converts the signal into an electrical signal. Reference numeral 4 denotes an outside air condition judgment unit, which has three input terminals 41,
The voltage signals of the respective signal output sections 1, 2, and 3 are inputted from 42 and 43, the arithmetic processing of the road surface freezing warning shown in FIG. 2 is executed, and an alarm signal is outputted from the output terminal 44. 5 is a display device that displays a road surface freezing warning. In a vehicle equipped with the road ice warning device configured as described above, when the vehicle key is inserted during driving, each part of the electrical system is activated by the vehicle battery. In addition, the condition determination unit 4 receives stabilized power from the on-vehicle battery and becomes operational, and executes the arithmetic processing shown in FIG. 2. In the arithmetic processing shown in FIG.
Then, input the outside air temperature (to) data from the outside air temperature signal output section 1, and proceed to step 102 to check whether the outside air temperature (to) is below a predetermined temperature (A°C) based on the outside air temperature (to) data. Determine whether If the outside air temperature is higher than A°C, it is assumed that there is no possibility of road surface freezing, and the processing after step 103 is not performed.
However, if the outside air temperature (to) is below A.degree. C., the processing from step 103 onwards is performed. Here, it is known that the dew point temperature (td) is approximately expressed by the following formula. That is, td=a(t+b)(+c)+d...(1) Here, t: dry bulb temperature, : relative humidity a, b, c, d: constants Now, constants a, b, c, d are expressed as follows: Decide as follows. a = 1.305 × 10 ^-3 b = 123.01 c = 668.71 d = 123.01 At this time, the dew point temperature is calculated from equation (1) in the range of -15t15℃ and 70100%, and the dew point temperature is calculated from the international equation of state for saturated vapor pressure. When calculating the difference from tdo,
The table below shows that it can be approximated by 0.3 or less.

【table】

[Table] Furthermore, relative humidity () is expressed as follows. = 100 × (e/e _w ) e: vapor pressure, e _w : saturated vapor pressure or saturated vapor pressure at dew point temperature (td) (e _w
(td)) is expressed as follows. e _w (td)={r/(R/R _v +r)}×po r: Mixing ratio, R: Gas constant of air R _v : Gas constant when water vapor is present po: Atmospheric pressure, therefore, atmospheric pressure Relative humidity at po (′)
becomes as follows. ′=/(po/p′) p′: 1 atmosphere Therefore, using this relative humidity (′), the outside air dew point temperature (td) can be calculated from equation (1). In step 105 of FIG. 2, the outside air dew point temperature (td) corrected using the atmospheric pressure obtained in this way is calculated and determined by the condition determining section 4, and in step 106, the difference with the previously input outside air temperature data is calculated. and predetermined temperature difference
Determine whether it is less than or equal to Bdeg. When it is determined that the road surface is frozen, the process proceeds to step 107, where a display lighting command is input to the display 5 to display a road surface freezing warning. Therefore, by repeatedly executing the above processing, if the road surface is frozen, a road surface freezing warning is displayed on the display 5, or a warning is given by voice, and if the road surface is not frozen, the display is turned off. In the above embodiment, the road surface temperature is constantly measured, but the driver or the like may operate a switch to determine whether or not to perform the road surface freezing determination process. Effects of the Invention As described above, according to the present invention, the dew point temperature of the outside air is determined by a calculator from the temperature of the outside air and the relative humidity corrected by atmospheric pressure. It is also possible to obtain highly reliable road surface freezing warnings accurately, and the system is small and lightweight, making it extremely useful in practice.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a road surface freezing warning device according to an embodiment of the present invention, and FIG. 2 is a flowchart showing arithmetic processing of the condition determining section in FIG. 1... Outside temperature signal output section, 2... Outside air humidity signal output section, 3... Atmospheric pressure signal output section, 4... Condition determination section, 5... Display device.

Claims (1)

[Claims] 1. A temperature signal output section and a humidity signal output section that are provided in the vehicle and that convert outside temperature and humidity into signals, an atmospheric pressure signal output section that converts atmospheric pressure into signals, and a temperature signal output section that converts outside air temperature and humidity into signals. A determination unit that receives the signal, humidity signal, and atmospheric pressure signal as input, calculates the dew point temperature of the outside air, and determines the frozen state of the road surface from the dew point temperature and the outside air temperature; and this determination unit determines the frozen state of the road surface. and a warning section that issues a road surface freeze warning. 2. The road surface freezing warning device according to claim 1, wherein the determination unit determines that the road surface is frozen when the difference between the outside air temperature and the dew point temperature of the outside air reaches a predetermined value.