WO2019035158A1 - Mobile body having reflection control layer - Google Patents

Mobile body having reflection control layer Download PDF

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Publication number
WO2019035158A1
WO2019035158A1 PCT/JP2017/029283 JP2017029283W WO2019035158A1 WO 2019035158 A1 WO2019035158 A1 WO 2019035158A1 JP 2017029283 W JP2017029283 W JP 2017029283W WO 2019035158 A1 WO2019035158 A1 WO 2019035158A1
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Prior art keywords
refractive index
reflection
air
layer
control layer
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PCT/JP2017/029283
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French (fr)
Japanese (ja)
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佐藤　裕一
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日産自動車株式会社
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Priority to JP2019536360A priority Critical patent/JP6849072B2/en
Priority to PCT/JP2017/029283 priority patent/WO2019035158A1/en
Publication of WO2019035158A1 publication Critical patent/WO2019035158A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62D—MOTOR VEHICLES; TRAILERS
    • B62D25/00—Superstructure or monocoque structure sub-units; Parts or details thereof not otherwise provided for
    • B62D25/20—Floors or bottom sub-units
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62D—MOTOR VEHICLES; TRAILERS
    • B62D29/00—Superstructures, understructures, or sub-units thereof, characterised by the material thereof

Definitions

  • the present invention relates to a movable body having a reflection control layer formed on the surface thereof.
  • the inventor of the present invention raises the temperature of air in the region (main stream) outside the region (boundary layer) where the flow velocity of air in the vicinity of the moving object is slowed in order to reduce the air resistance of the moving object. Found that it is effective.
  • the reflectance for road surface radiation (light in a wavelength range of 3 ⁇ m or more, such as mid-infrared rays and far-infrared rays) from below the vehicle emitted from the road surface is low. Therefore, since the intensity of the reflected light by the road surface radiation is weak, there is a problem that the drag of the vehicle can not be reduced by reducing the drag of the vehicle.
  • This invention is made in view of such a subject, The objective is to raise the temperature of the mainstream air around a mobile body, and to reduce the air resistance of a mobile body.
  • a reflection control layer that reflects road surface radiation is formed on the lower surface of the moving body, and the reflection control layer reflects light in a wavelength range of 3 ⁇ m to 100 ⁇ m.
  • the reflectance to the road surface radiation is improved, the light reflected by the lower surface of the moving body heats the air existing between the road surface and the moving body, and the movement is performed by the decrease of the density of the heated air. Air resistance to the body can be reduced.
  • FIG. 1 is a schematic view of the flow of air generated around a car according to a first embodiment of the present invention.
  • FIG. 2 is a partial cross-sectional view of the vicinity of the surface of the automobile according to the first embodiment of the present invention along the traveling direction of the automobile.
  • FIG. 3 is an enlarged sectional view showing the structure of the surface of the automobile according to the first embodiment of the present invention.
  • FIG. 4 is a graph showing verification results of the temperature rise of the main flow due to the reflected light.
  • FIG. 5 is a diagram showing how light is refracted in a thin film sandwiched by substances of different refractive indices.
  • FIG. 6 is a view showing the positional relationship between the lower surface of the vehicle and the road surface according to the first embodiment of the present invention.
  • FIG. 7 is an enlarged sectional view showing the structure of the surface of the automobile according to the second embodiment of the present invention.
  • FIG. 8A is a side view illustrating the incident angle of the road surface radiation with respect to the lower surface of the vehicle according to the second embodiment of the present invention.
  • FIG. 8B is a front view illustrating the incident angle of the road surface radiation to the lower surface of the automobile according to the second embodiment of the present invention.
  • FIG. 9 is a graph showing the relationship between the incident angle of light and the thickness of the reflection enhancing layer.
  • FIG. 1 is a schematic view of the flow of air generated during traveling of the vehicle according to the present embodiment.
  • FIG. 2 is an enlarged cross-sectional view of the vicinity of the surface of the vehicle according to the present embodiment along the traveling direction of the vehicle.
  • FIG. 3 is an enlarged cross-sectional view showing the structure of the surface of the vehicle according to the present embodiment.
  • a car body coating layer 20 is formed on the surface of the automobile 1, and a reflection control layer 21 is further formed on the car body coating layer 20.
  • the reflection control layer 21 reflects light in the wavelength range of solar light (0.3 ⁇ m to 100 ⁇ m).
  • the type and thickness of the reflection control layer 21 can be changed according to the position of the surface of the vehicle.
  • the wavelength range of sunlight is composed of the wavelength range of near-ultraviolet light (0.3 ⁇ m to 0.38 ⁇ m), the visible light range (0.38 ⁇ m to 0.75 ⁇ m), and the wavelength range of infrared radiation (0.75 ⁇ m to 100 ⁇ m) .
  • the wavelength range of infrared radiation is composed of the wavelength range of near infrared (0.75 ⁇ m to 3 ⁇ m) and the wavelength range of middle infrared and far infrared (3 ⁇ m to 100 ⁇ m).
  • the wavelength range of 0.75 ⁇ m to 0.78 ⁇ m is the heat absorption band (oxygen A band) of oxygen molecules in air.
  • ⁇ Flow of air around a moving car> As shown in FIG. 1, when viewed from the stationary system of the car 1, a flow of air along the surface of the car 1 occurs around the moving car 1. As shown in FIG. 2, in the vicinity of the surface of the automobile 1, the flow of air is delayed by the viscous friction generated between the air and the surface of the automobile, and the boundary layer 41 is formed. In the boundary layer 41, the velocity of the air increases with distance from the surface of the automobile 1, and the velocity of the air approaches the relative velocity of the automobile with respect to the air.
  • the flow of air in the outer region 43 is referred to as the main flow 2.
  • the force received from the air by the automobile 1 during traveling is represented by forces in axial directions in front and rear, left and right, and upper and lower axes of the automobile 1 and moments around each axis, collectively called aerodynamic six component forces.
  • an automobile 1 during running force from the air is represented by dimensionless
  • the air resistance F is especially the longitudinal direction of the force, represented by the air resistance coefficient C d represented by the following formula 1.
  • ⁇ is the density of air in the outer region 43
  • A is the front projection area with respect to the traveling direction of the car 1
  • V is the relative velocity of the car 1 with respect to the main flow.
  • Drag coefficient C d is the product of the air dynamic pressure "pV 2/2" and front projection area A, a value obtained by dividing the air resistance F.
  • the air resistance coefficient Cd is an amount determined depending on the shape of the automobile 1, and affects the fuel consumption during traveling, the maximum speed, the acceleration performance, and the like.
  • the air resistance F of an object such as the car 1 is dominated by pressure resistance when viewed as a whole of the car 1, and the frictional resistance that is a problem in aircraft is small in the car 1. Therefore, in order to reduce the air resistance F in the automobile 1, it is effective to focus on reducing the pressure resistance.
  • the front projection area A is regarded as a parameter that can be handled by the vehicle design in order to reduce pressure resistance.
  • the mainstream air density ⁇ and the velocity V can be varied according to the traveling environment of the vehicle, they are not regarded as parameters that can be handled by the vehicle design.
  • the inventor of the present invention has considered that the mainstream air density ⁇ can be a parameter that can be handled by the design of a vehicle in order to reduce pressure resistance. Then, focusing on the fact that the pressure resistance that occupies most of the air resistance F is proportional to the air density ⁇ of the main flow, heating the main air lowers the main air density ⁇ and consequently reduces the air resistance F It is found that it is possible to
  • Mainstream air can not be heated directly because it is located away from the surface of the car 1.
  • the reflection control layer 21 that reflects light in a predetermined wavelength range on the surface of the automobile 1, light emitted from the sun, clouds, water vapor in the air, etc., infrared rays emitted from the road surface, etc. The light is reflected by the reflection control layer 21 and the reflected light can heat the mainstream air.
  • the air resistance of the moving body can be reduced by having the reflection control layer in the moving body.
  • the inventor places the fender of the car in the wind tunnel to imitate the traveling environment of the car and places the fender portion in a state where the air flows. Irradiated with simulated sunlight. Then, it was measured how much the temperature of the air flowing through the site irradiated with the artificial sunlight rises before and after passing through the site.
  • three types of fenders of the same shape and different in painting were prepared and verified.
  • the paint layer formed on the fender corresponds to the reflection control layer 21 in the present embodiment.
  • FIG. 4 is a graph showing verification results of the temperature rise of the main flow due to the reflected light.
  • FIG. 4 shows the evaluation results according to experimental examples 1 to 3 for which verification was performed, and reference numeral 81 represents experimental example 1 with a standard black coating called “super black”, and reference numeral 82 represents Experimental example 2 given a standard white paint called “white pearl”, numeral 83 corresponds to experimental example 3 given a silver color coating by "silver plating".
  • the average reflectance in the wavelength range from the ultraviolet wavelength to the far infrared wavelength increases in the order of Experimental Examples 1, 2, and 3.
  • the "average reflectance” is an average value of the spectral reflectance (reflectance for monochromatic light) in a designated wavelength range. That is, the spectral reflectance which is a function of wavelength is measured in a designated wavelength range, and a value obtained by averaging the spectral reflectance measured over the designated wavelength range is defined as “average reflectance”. There is.
  • thermocouple 31a was placed at a distance d from the surface of the car fender in the direction perpendicular to the surface, along the air flow, upstream of the site to be irradiated with the artificial sunlight.
  • the thermocouple 31b was placed downstream of the site to which the pseudo-sunlight was irradiated.
  • the distance d was set to 18 mm so that the thermocouple was placed in the main flow outside the boundary layer on the surface of the fender.
  • the thermocouple 31a and the thermocouple 31b were disposed at intervals of 200 mm along the flow of air, and the section sandwiched by the thermocouple 31a and the thermocouple 31b was irradiated with simulated sunlight.
  • the speed of mainstream air to the fender was 40 km / h.
  • thermocouples 31a and 31b The temperature of the air measured by the thermocouple 31a is the temperature of the air just before being warmed by the pseudo-sunlight reflected by the fender, and the temperature of the air measured by the thermocouple 31b is the pseudo-sun reflected by the fender It is the temperature of air just warmed by light.
  • thermocouple 31 b As shown in FIG. 4, it was found that the temperature measured by the thermocouple 31 b was higher than the temperature measured by the thermocouple 31 a. Furthermore, it turned out that temperature rise (DELTA) T becomes large in order of Experimental example 1,2,3. That is, it was found that the temperature rise ⁇ T becomes larger as the average reflectance of the paint on the surface of the automobile is larger.
  • DELTA temperature rise
  • the reflection control layer 21 is provided on the lower surface of the automobile 1 in order to use the road surface radiation for reducing the air resistance of the vehicle. Further, in order to improve the reflectance of light in a predetermined wavelength range, the thickness of the reflection increasing layer 25 provided in the reflection control layer 21 is adjusted. The aspect will be described next.
  • FIG. 5 is a diagram showing how light is refracted in a thin film sandwiched by substances of different refractive indices.
  • the optical path difference L (difference in optical distance) generated between the light reflected at the boundary between the medium M1 and the thin film I and the light reflected at the boundary between the thin film I and the medium M2 is represented by Equation 2 below Be done.
  • the intensity reflectance R in the case where light incident on the thin film I from the side of the medium M1 is multi-reflected by the thin film I and then reflected back to the medium M1 again is calculated.
  • Equation 4 the parameter ⁇ is expressed by Equation 4 below.
  • the intensity reflectance R is expressed by the following equation 5.
  • Equation 7 The amplitude reflectance r 1 and amplitude reflectance r 2, the following equation 6 is expressed as Equation 7.
  • Equation 8 the intensity reflectance R is expressed by Equation 8 below.
  • the intensity reflectance R is zero if the following two conditions are satisfied.
  • the first condition is referred to as amplitude condition is that the amplitude reflectance r 1 and amplitude reflectance r 2 equal.
  • the refractive index n is expressed as the following Expression 9 using the refractive index n 0 and the refractive index n m .
  • the second condition is called a phase condition and is expressed as Equation 10.
  • m is an integer of 0 or more.
  • the first condition is a condition in which the amplitudes of the light reflected at the boundary between the medium M1 and the thin film I and the light reflected at the boundary between the thin film I and the medium M2 coincide.
  • the second condition is that the phase difference between the light reflected at the boundary between the medium M1 and the thin film I and the light reflected at the boundary between the thin film I and the medium M2 is half the wavelength of the incident light. It is an odd multiple, which is a condition that cancels out at the peaks and valleys of the waves.
  • Equation 11 can be obtained for the thickness d.
  • the wavelength ⁇ can take any value within a predetermined wavelength range when defining the average reflectance. Therefore, the term “cos (2 ⁇ )” appearing in the denominator of the second term on the right side of Formula 8 can take values from ⁇ 1 to 1.
  • R 1 is not present film I in FIG. 5, is equal to the intensity reflectance at the boundary between the medium M1 and the medium M2 in the case of the medium M1 and the medium M2 is in direct contact.
  • the intensity reflectance R is a function that oscillates between R 1 and R 2 described above according to the wavelength ⁇ .
  • R 1 is a constant independent of the refractive index n, in order to increase the average reflectance in the situation shown in FIG. 5 as compared to the case where the thin film I is not provided, “R 1 ⁇ R 2 Should be satisfied.
  • condition for the refractive index n is derived from the conditional expression “R 1 > R 2 ” for reducing the average reflectance, “n 0 ⁇ n ⁇ n m ” or “n m ⁇ n ⁇ n 0 ” is obtained. .
  • Equation 14 does not seem to set the upper limit for thickness d.
  • the value of m is set such that the thickness of the practical thin film I is included in the range of the thickness d determined by Equation 14 within the practical range of refractive index. select. Under such m, Equation 14 gives an upper limit on the thickness d, by choosing the maximum value of m that is acceptable within the practical range of refractive index.
  • a material having a small refractive index includes silver (refractive index is 0.12 at 563 nm). Further, as a material having a large refractive index, germanium (refractive index of 5.75 at 590 nm) can be mentioned.
  • the refractive index is not dependent on the wavelength, and furthermore, the case of normal incidence is assumed.
  • the above examination results can be applied qualitatively even in the case where the refractive index depends on the wavelength or in the case where the normal incidence is not performed.
  • a reflection control layer 21 that reflects road surface radiation (light in a wavelength range of 3 ⁇ m or more, such as middle infrared rays and far infrared rays) is used as the lower surface 116 of the vehicle (lower surface of moving body). It is formed in.
  • the reflection control layer 21 reflects light in a wavelength range of 3 ⁇ m to 100 ⁇ m in order to utilize road surface radiation incident on the automobile 1 for heating the main flow 2 existing around the automobile 1 during traveling.
  • the average reflectance of the reflection control layer 21 in the wavelength range of 3 ⁇ m to 100 ⁇ m is 4% or more so that the heating effect of the main flow 2 existing around the traveling automobile 1 can be sufficiently obtained.
  • a wavelength range in which the refractive index of the reflection control layer 21 is 1.5 or more is sufficient.
  • the medium M1 is air
  • the medium M2 is a reflection control layer 21
  • the thickness d of the thin film I is 0, the refractive index of air is 1 and the refractive index of the reflection control layer 21 is 1.
  • R 1 is calculated for a wavelength of 5 or more, R 1 is 4% or more.
  • the reflection control layer 21 and the air are in direct contact with each other, it is sufficient if there is a wavelength at which the refractive index of the reflection control layer 21 has a predetermined value or less in the wavelength range.
  • the refractive index of the reflection control layer 21 is 0.66 or less.
  • the medium M1 is air
  • the medium M2 is a reflection control layer 21
  • the thickness d of the thin film I is 0, the refractive index of air is 1 and the refractive index of the reflection control layer 21 is 0.
  • R 1 is calculated for a wavelength of 66 or less, R 1 is 4% or more.
  • the average reflectance in the wavelength range of 3 ⁇ m to 100 ⁇ m may be 4% or more.
  • the under-vehicle surface 116 may be perpendicular to the direction of the road surface radiation.
  • the direction of the road surface radiation refers to a direction that is vertically upward with respect to the road surface 200. That is, the reflection control layer 21 formed on the lower surface 116 of the vehicle and the lower surface 116 of the vehicle may be perpendicular to the direction of the road surface radiation (the reflection control layer 21 formed on the lower surface 116 of the vehicle is Parallel)).
  • the reflection control layer 21 reflects light in the wavelength range of 3 ⁇ m to 100 ⁇ m, the light reflected by the surface of the automobile 1 heats the main flow 2 existing around the traveling automobile 1. Since the density of the mainstream 2 is reduced by heating, the air resistance F of the automobile 1 can be reduced.
  • the main stream 2 between the lower car surface 116 and the road surface 200 can be heated to reduce the density of the main stream 2.
  • the average reflectance of the reflection control layer 21 in the wavelength range of 3 ⁇ m to 100 ⁇ m is 4% or more, the reflected light density of the road surface radiation by the reflection control layer 21 can be increased.
  • the air resistance F of the automobile 1 can be reduced.
  • the temperature rise over the entire length of the vehicle is about 5K.
  • the lower surface 116 of the automobile has an angle perpendicular to or nearly perpendicular to the direction of the road surface radiation, the effect of increasing the reflected light density of the road surface radiation by the reflection control layer 21 is further enhanced. This is because "the phenomenon of confinement of road surface radiation" occurs between the reflection control layer 21 and the road surface 200.
  • “Containment phenomenon of road surface radiation” means that road surface radiation reflected by the lower surface 116 of the automobile is absorbed and reflected by the road surface 200 again.
  • the road surface radiation reflected by the lower surface 116 of the car is again absorbed and reflected by the road surface 200 and can be reused to heat the main flow 2 located between the lower surface 116 of the car and the road surface 200.
  • the mainstream 2 located between the lower surface 116 of the vehicle and the road surface 200 is heated by the road surface radiation from the road surface 200 and the reflected light from the reflection control layer 21, so the effect of reducing the air resistance F is increased.
  • the vehicle according to the second embodiment of the present invention differs from the first embodiment in that a reflection enhancing layer 25 is provided.
  • the other configurations, operations, and effects not described in the second embodiment are substantially the same as those in the first embodiment, and thus redundant description will be omitted.
  • FIG. 7 is an enlarged sectional view showing the structure of the surface of the vehicle according to the present embodiment.
  • a car body coating layer 20 is formed on the surface of the automobile 1, and a reflection control layer 21 is further formed on the car body coating layer 20.
  • the reflection control layer 21 is provided with a reflection increasing layer 25 for reflecting light in a wavelength range of 3 ⁇ m to 100 ⁇ m.
  • the reflection increasing layer 25 is provided on the reflection control layer 21
  • various aspects can be considered, such as an aspect in which the reflection control layer 21 itself is the reflection enhancing layer 25.
  • stacks the reflection increase layer 25 on the reflection control layer 21 is demonstrated. The same effect can be obtained also in an embodiment which will not be described below.
  • a reflection increasing layer 25 for reflecting road surface radiation is laminated on the reflection control layer 21.
  • the reflection control layer 21 in order to use the road surface radiation to heat the main flow 2 existing around the traveling automobile 1, it is formed so that the average reflectance of the reflection enhancing layer 25 to light in the wavelength range of 3 .mu.m to 100 .mu.m is high. There is.
  • the reflection enhancing layer 25 reflects light in a wavelength range of 3 ⁇ m to 100 ⁇ m will be examined.
  • the thin film I, the medium M1, and the medium M2 shown in FIG. 5 correspond to the reflection increasing layer 25, the air, and the reflection control layer 21 (the vehicle-side material), respectively.
  • the reflection increasing layer 25 is formed of a material having a refractive index larger than both of the refractive index of the reflection control layer 21 (body side material) and the refractive index of air. It should just be.
  • the reflection increasing layer 25 may be formed of a material having a refractive index smaller than both of the refractive index of the reflection control layer 21 (body-side material) and the refractive index of air in a wavelength range of 3 ⁇ m to 100 ⁇ m.
  • the refractive index of the reflection increasing layer 25 has a value outside the range between the refractive index of the reflection control layer 21 (the vehicle-side material) and the refractive index of air in the wavelength range of 3 ⁇ m to 100 ⁇ m.
  • the thickness of the reflection increasing layer 25 is preferably in the range of about 20 ⁇ m to 40 ⁇ m from the viewpoint of easiness of production and securing of quality.
  • the thickness of the reflection increasing layer 25 is equal to or more than 750 nm divided by the refractive index n of the reflection increasing layer 25 and equal to or less than 275000 nm divided by the refractive index n of the reflection increasing layer 25.
  • the refractive index of the reflection increasing layer 25 is a value outside the range between the refractive index of the reflection control layer 21 (body-side material) and the refractive index of air, comparison with the case where the reflection increasing layer 25 is not provided
  • the average reflectance in the 3 ⁇ m to 100 ⁇ m wavelength region of the surface of the automobile 1 is increased by the presence of the reflection enhancing layer 25. Therefore, the road surface radiation from the road surface 200 can be efficiently reflected.
  • the light reflected by the surface of the automobile 1 heats the main flow 2 existing around the traveling automobile 1. Since the density of the mainstream 2 is reduced by heating, the air resistance F of the automobile 1 can be reduced.
  • the thickness of the reflection increasing layer 25 is adjusted so as to fall within the thickness range determined by Equation 14, and the thickness of the reflection increasing layer 25 is 750 nm.
  • the value is equal to or greater than the value divided by n and equal to or less than the value divided by the refractive index n of the reflection increasing layer 25 at 275,000 nm. Therefore, the average reflectance in the wavelength range of 3 ⁇ m to 100 ⁇ m is maximized. As a result, the air resistance F of the automobile 1 can be reduced by the reflected light of the road surface radiation.
  • the refractive index of the reflection increasing layer 25 is the reflection control layer 21 (body-side material) in order to obtain the effect of more reliably increasing the average reflectance and reducing the air resistance F of the automobile 1 by heating by reflected light.
  • the refractive index of the optical system of the present invention may be 1.01 times or more of the refractive index of the light emitting element and 1.01 times or more of the refractive index of air.
  • the refractive index of the reflection increasing layer 25 may be 0.99 times or less of the refractive index of the reflection control layer 21 (body-side material) and 0.99 times or less of the refractive index of air. .
  • the refractive index of the reflection increasing layer 25 is made as large as possible both of the refractive index of the reflection control layer 21 (body-side material) and the refractive index of air within the practical refractive index range while satisfying the above conditions.
  • FIG. 8A is a side view for explaining the incident angle of the road surface radiation with respect to the lower surface of the vehicle according to the present embodiment.
  • FIG. 8B is a front view illustrating the incident angle of the road surface radiation with respect to the lower surface of the automobile according to the present embodiment.
  • FIG. 9 is a graph showing the relationship between the incident angle of light and the thickness of the reflection increasing layer.
  • the condition where road surface radiation is incident on the undersurface 116 of a car from the road surface 200 is considered.
  • the road surface radiation is perpendicularly incident on the reflection increasing layer 25 in a portion (hereinafter, a horizontal portion) horizontal to the traveling direction of the automobile 1.
  • an inclined portion there may be a portion (hereinafter referred to as an inclined portion) which is not horizontal with respect to the traveling direction of the automobile 1, such as a surface connecting the tire housing and the central portion of the automobile 1.
  • the light does not perpendicularly enter the reflection enhancing layer 25 at the inclined portion.
  • the incident angle of the road surface radiation with respect to the inclined portion is ⁇ .
  • the size of the square root of Equation 2 decreases. If the optical path difference L is the same in the reflection increasing layer 25 at the horizontal portion and the reflection increasing layer 25 at the inclined portion, focusing on the fact that the same average reflectance is realized at the horizontal portion and the inclined portion, as shown in FIG. Thus, as the incident angle ⁇ increases from 0 ° and approaches 90 °, it is necessary to increase the thickness d of the reflection increasing layer 25 at the inclined portion.
  • the thickness of the reflection increasing layer 25 at the inclined portion may be increased as compared with the thickness of the reflection increasing layer 25 at the horizontal portion. Further, as the inclination angle ⁇ becomes larger, the thickness of the reflection increasing layer 25 at the inclined portion may be increased.
  • the reflection increasing layer 25 at the inclined portion can also efficiently reflect the road surface radiation. As a result, the air resistance F of the automobile 1 can be reduced by the reflected light.
  • the present invention is applicable to a moving body that moves in the air besides the car.
  • mobile objects include motorcycles, railways, aircrafts, rockets, etc. in addition to automobiles.

Abstract

A reflection control layer (21) which reflects light in the road surface radiation wavelength region from 3 μm to 100 μm is formed on the mobile body bottom surface (116) of the mobile body (1) that faces the road surface, and air resistance of the mobile body (1) is reduced by heating the free stream (2) outside of the mobile body (21) by means of reflected light.

Description

反射制御層を有する移動体Mobile body having reflection control layer
　本発明は、その表面に反射制御層が形成された移動体に関する。 The present invention relates to a movable body having a reflection control layer formed on the surface thereof.
　従来から、鉄道車両内の冷房による消費電力を抑制するため、０．７８μｍ～２．１μｍの波長域にある光に対する反射率を増加させることにより、色調を変えることなく鉄道車両に近赤外線反射性能を付与する方法が知られている（特許文献１参照）。 Conventionally, in order to suppress power consumption by cooling in a railway vehicle, the near infrared reflection performance to the railway vehicle without changing the color tone by increasing the reflectance to light in the wavelength range of 0.78 μm to 2.1 μm. There is known a method of imparting (see Patent Document 1).
特開２００６－２１３０９５号公報JP 2006-213095 A
　一方、本発明の発明者は、移動体の空気抵抗を低減するために、移動体の近傍の空気の流速が遅くなる領域（境界層）の外側の領域（主流）の空気の温度を上げることが有効であるという知見を得た。 On the other hand, the inventor of the present invention raises the temperature of air in the region (main stream) outside the region (boundary layer) where the flow velocity of air in the vicinity of the moving object is slowed in order to reduce the air resistance of the moving object. Found that it is effective.
　しかし、特許文献１に記載された方法によれば、路面から発せられる車両下方からの路面放射（中赤外線および遠赤外線などの、３μｍ以上の長さの波長域の光）に対する反射率が低い。そのため、路面放射による反射光の強度が弱いため、車両の空気抵抗を下げて、抗力を低減することができないという問題がある。 However, according to the method described in Patent Document 1, the reflectance for road surface radiation (light in a wavelength range of 3 μm or more, such as mid-infrared rays and far-infrared rays) from below the vehicle emitted from the road surface is low. Therefore, since the intensity of the reflected light by the road surface radiation is weak, there is a problem that the drag of the vehicle can not be reduced by reducing the drag of the vehicle.
　本発明は、このような課題に鑑みてなされたものであり、その目的は、移動体の周囲の主流の空気の温度を上げて移動体の空気抵抗を低減させることである。 This invention is made in view of such a subject, The objective is to raise the temperature of the mainstream air around a mobile body, and to reduce the air resistance of a mobile body.
　本発明に係る移動体には、路面放射を反射する反射制御層が移動体下面に形成されており、反射制御層は、３μｍから１００μｍまでの波長域にある光を反射する。 In the moving body according to the present invention, a reflection control layer that reflects road surface radiation is formed on the lower surface of the moving body, and the reflection control layer reflects light in a wavelength range of 3 μm to 100 μm.
　本発明によれば、路面放射に対する反射率が向上するので、移動体下面で反射された光によって、路面と移動体の間に存在する空気を加熱し、加熱された空気の密度の低下によって移動体に対する空気抵抗を低減することができる。 According to the present invention, since the reflectance to the road surface radiation is improved, the light reflected by the lower surface of the moving body heats the air existing between the road surface and the moving body, and the movement is performed by the decrease of the density of the heated air. Air resistance to the body can be reduced.
図１は、本発明の第１実施形態に係る自動車の周りに生じる空気の流れの模式図である。FIG. 1 is a schematic view of the flow of air generated around a car according to a first embodiment of the present invention. 図２は、本発明の第１実施形態に係る自動車の表面近傍の、自動車の進行方向に沿った一部断面図である。FIG. 2 is a partial cross-sectional view of the vicinity of the surface of the automobile according to the first embodiment of the present invention along the traveling direction of the automobile. 図３は、本発明の第１実施形態に係る自動車の表面の構造を示す拡大断面図である。FIG. 3 is an enlarged sectional view showing the structure of the surface of the automobile according to the first embodiment of the present invention. 図４は、反射光による主流の温度上昇の検証結果を示すグラフ図である。FIG. 4 is a graph showing verification results of the temperature rise of the main flow due to the reflected light. 図５は、異なる屈折率の物質によって挟まれた薄膜における光の屈折の様子を示す図である。FIG. 5 is a diagram showing how light is refracted in a thin film sandwiched by substances of different refractive indices. 図６は、本発明の第１実施形態に係る自動車の下面と路面の位置関係を示す図である。FIG. 6 is a view showing the positional relationship between the lower surface of the vehicle and the road surface according to the first embodiment of the present invention. 図７は、本発明の第２実施形態に係る自動車の表面の構造を示す拡大断面図である。FIG. 7 is an enlarged sectional view showing the structure of the surface of the automobile according to the second embodiment of the present invention. 図８Ａは、本発明の第２実施形態に係る自動車の下面に対する、路面放射の入射角を説明する側面図である。FIG. 8A is a side view illustrating the incident angle of the road surface radiation with respect to the lower surface of the vehicle according to the second embodiment of the present invention. 図８Ｂは、本発明の第２実施形態に係る自動車の下面に対する、路面放射の入射角を説明する正面図である。FIG. 8B is a front view illustrating the incident angle of the road surface radiation to the lower surface of the automobile according to the second embodiment of the present invention. 図９は、光の入射角と反射増加層の厚みの関係を示すグラフ図である。FIG. 9 is a graph showing the relationship between the incident angle of light and the thickness of the reflection enhancing layer.
　図面を参照して、本発明の実施形態を説明する。図面の記載において同一部分には同一符号を付し説明を省略する。以下では、移動体が自動車である場合を挙げて説明する。 Embodiments of the present invention will be described with reference to the drawings. In the description of the drawings, the same parts will be denoted by the same reference numerals and the description thereof will be omitted. Below, the case where a mobile body is a car is mentioned and explained.
（第１実施形態）
　図１は、本実施形態に係る自動車の、走行中に生じる空気の流れの模式図である。また、図２は、本実施形態に係る自動車の表面近傍の、自動車の進行方向に沿った拡大断面図である。図３は、本実施形態に係る自動車の表面の構造を示す拡大断面図である。 First Embodiment
FIG. 1 is a schematic view of the flow of air generated during traveling of the vehicle according to the present embodiment. FIG. 2 is an enlarged cross-sectional view of the vicinity of the surface of the vehicle according to the present embodiment along the traveling direction of the vehicle. FIG. 3 is an enlarged cross-sectional view showing the structure of the surface of the vehicle according to the present embodiment.
　図３に示すように、自動車１の表面には車体塗装層２０が形成され、さらに車体塗装層２０の上に反射制御層２１が形成されている。 As shown in FIG. 3, a car body coating layer 20 is formed on the surface of the automobile 1, and a reflection control layer 21 is further formed on the car body coating layer 20.
　反射制御層２１は、太陽光の波長域（０．３μｍ～１００μｍ）にある光を反射する。なお、反射制御層２１の種類や厚みは、自動車の表面の位置に応じて変更されうるものである。 The reflection control layer 21 reflects light in the wavelength range of solar light (0.3 μm to 100 μm). The type and thickness of the reflection control layer 21 can be changed according to the position of the surface of the vehicle.
　太陽光の波長域は、近紫外線の波長域（０．３μｍ～０．３８μｍ）、可視光域（０．３８μｍ～０．７５μｍ）、赤外放射の波長域（０．７５μｍ～１００μｍ）からなる。また、赤外放射の波長域は、近赤外線の波長域（０．７５μｍ～３μｍ）及び中赤外線および遠赤外線の波長域（３μｍ～１００μｍ）からなる。 The wavelength range of sunlight is composed of the wavelength range of near-ultraviolet light (0.3 μm to 0.38 μm), the visible light range (0.38 μm to 0.75 μm), and the wavelength range of infrared radiation (0.75 μm to 100 μm) . The wavelength range of infrared radiation is composed of the wavelength range of near infrared (0.75 μm to 3 μm) and the wavelength range of middle infrared and far infrared (3 μm to 100 μm).
　近赤外線の波長域のうち、０．７５μｍ～０．７８μｍの波長域は、空気中の酸素分子の熱吸収帯（酸素Ａバンド）である。 Of the near-infrared wavelength range, the wavelength range of 0.75 μm to 0.78 μm is the heat absorption band (oxygen A band) of oxygen molecules in air.
　＜走行中の自動車の周りの空気の流れ＞
　図１に示すように、自動車１の静止系で見たとき、走行中の自動車１の周りには自動車１の表面に沿った空気の流れが発生する。図２に示すように、自動車１の表面近傍では、空気と自動車の表面との間に生じる粘性摩擦によって空気の流れは遅くなっており、境界層４１が形成されている。境界層４１では、自動車１の表面から離れるほど空気の速度は大きくなり、空気の速度は、空気に対する自動車の相対速度に近づいていく。 <Flow of air around a moving car>
As shown in FIG. 1, when viewed from the stationary system of the car 1, a flow of air along the surface of the car 1 occurs around the moving car 1. As shown in FIG. 2, in the vicinity of the surface of the automobile 1, the flow of air is delayed by the viscous friction generated between the air and the surface of the automobile, and the boundary layer 41 is formed. In the boundary layer 41, the velocity of the air increases with distance from the surface of the automobile 1, and the velocity of the air approaches the relative velocity of the automobile with respect to the air.
　自動車１の表面から離れて境界４２よりも外側の外部領域４３では、もはや空気と自動車の表面との間に生じる粘性摩擦の影響はなくなっており、空気の速度は、空気に対する自動車の相対速度にほぼ等しくなっている。外部領域４３における空気の流れを主流２と呼ぶ。 In the outer region 43 outside the boundary 42 away from the surface of the automobile 1, the influence of the viscous friction generated between the air and the surface of the automobile is no longer present, and the velocity of the air is the velocity of the vehicle relative to the air. It is almost equal. The flow of air in the outer region 43 is referred to as the main flow 2.
　＜空気抵抗低減のメカニズム＞
　次に、所定の波長域にある光を反射する反射制御層２１を自動車１が有することによって、自動車１の空気抵抗が低減されるメカニズムを説明する。 <Mechanism to reduce air resistance>
Next, a mechanism by which the air resistance of the automobile 1 is reduced by the automobile 1 having the reflection control layer 21 that reflects light in a predetermined wavelength range will be described.
　一般に、走行中の自動車１が空気から受ける力は、自動車１の前後、左右、上下の各軸方向の力と各軸周りのモーメントで表され、総称して空力六分力と呼ばれる。通常、走行中の自動車１が空気から受ける力は無次元化して表され、特に前後方向の力である空気抵抗Ｆは、次の数式１によって表される空気抵抗係数Ｃｄによって表される。ここで、ρは、外部領域４３の空気の密度、Ａは、自動車１の進行方向に対する前面投影面積、Ｖは、主流に対する自動車１の相対速度である。 In general, the force received from the air by the automobile 1 during traveling is represented by forces in axial directions in front and rear, left and right, and upper and lower axes of the automobile 1 and moments around each axis, collectively called aerodynamic six component forces. Usually, an automobile 1 during running force from the air is represented by dimensionless, the air resistance F is especially the longitudinal direction of the force, represented by the air resistance coefficient C d represented by the following formula 1. Here, ρ is the density of air in the outer region 43, A is the front projection area with respect to the traveling direction of the car 1, and V is the relative velocity of the car 1 with respect to the main flow.
Figure JPOXMLDOC01-appb-M000001
Figure JPOXMLDOC01-appb-M000001
　空気抵抗係数Ｃｄは、空気の動圧「ρＶ２／２」と前面投影面積Ａの積によって、空気抵抗Ｆを除した値である。空気抵抗係数Ｃｄは、自動車１の形状に依存して決まる量であり、走行時の燃費、最高速度、加速性能などに影響を及ぼす。自動車１のような物体の空気抵抗Ｆは、自動車１全体でみたときには圧力抵抗が支配的であり、航空機で問題となる摩擦抵抗は自動車１では小さい。そのため、自動車１において空気抵抗Ｆを低減するためには、圧力抵抗を小さくすることに着目するのが効果的である。 Drag coefficient C d is the product of the air dynamic pressure "pV 2/2" and front projection area A, a value obtained by dividing the air resistance F. The air resistance coefficient Cd is an amount determined depending on the shape of the automobile 1, and affects the fuel consumption during traveling, the maximum speed, the acceleration performance, and the like. The air resistance F of an object such as the car 1 is dominated by pressure resistance when viewed as a whole of the car 1, and the frictional resistance that is a problem in aircraft is small in the car 1. Therefore, in order to reduce the air resistance F in the automobile 1, it is effective to focus on reducing the pressure resistance.
　上記着目に基づいて数式１を見直すと、通常の自動車の設計において、前面投影面積Ａは、圧力抵抗を小さくするために車両の設計で対応可能なパラメータとしてみなされる。一方、主流の空気密度ρ、および、速度Ｖについては、自動車の走行環境に応じて変動しうるものであるため、車両の設計で対応可能なパラメータとしてみなされない。 Reviewing Equation 1 based on the above-mentioned attention, in a typical automobile design, the front projection area A is regarded as a parameter that can be handled by the vehicle design in order to reduce pressure resistance. On the other hand, since the mainstream air density ρ and the velocity V can be varied according to the traveling environment of the vehicle, they are not regarded as parameters that can be handled by the vehicle design.
　しかしながら、上記の既存概念の枠にとらわれることなく、本発明の発明者は、主流の空気密度ρは、圧力抵抗を小さくするために車両の設計で対応可能なパラメータとなりうると考えた。そして、空気抵抗Ｆの大部分を占める圧力抵抗が主流の空気密度ρに比例することに着目し、主流の空気を加熱することで主流の空気密度ρを下げ、その結果、空気抵抗Ｆを低減することが可能であるとの知見を得た。 However, without being bound by the above-mentioned existing concept, the inventor of the present invention has considered that the mainstream air density ρ can be a parameter that can be handled by the design of a vehicle in order to reduce pressure resistance. Then, focusing on the fact that the pressure resistance that occupies most of the air resistance F is proportional to the air density ρ of the main flow, heating the main air lowers the main air density ρ and consequently reduces the air resistance F It is found that it is possible to
　主流の空気は、自動車１の表面から離れた場所にあるため、直接に加熱することはできない。しかしながら、所定の波長域にある光を反射する反射制御層２１を自動車１の表面に設けることにより、太陽、雲、空気中の水蒸気などから照射される光や、路面から放射される赤外線などの光が、反射制御層２１によって反射され、反射された光によって主流の空気を加熱することができる。 Mainstream air can not be heated directly because it is located away from the surface of the car 1. However, by providing the reflection control layer 21 that reflects light in a predetermined wavelength range on the surface of the automobile 1, light emitted from the sun, clouds, water vapor in the air, etc., infrared rays emitted from the road surface, etc. The light is reflected by the reflection control layer 21 and the reflected light can heat the mainstream air.
　以上の理由により、反射制御層を移動体が有することによって、移動体の空気抵抗が低減される。 For the above reasons, the air resistance of the moving body can be reduced by having the reflection control layer in the moving body.
　＜反射光による主流の温度上昇＞
　上述したメカニズムで実際に主流の空気を加熱可能であることを検証するため、発明者は自動車の走行環境を模すため、風洞内に自動車のフェンダーを配置し、空気が流れる状態でフェンダー部分に疑似太陽光を照射した。そして、疑似太陽光が照射された部位を流れる空気が、当該部位を通過する前後でどの程度、温度上昇するかを測定した。ここで、同一形状のフェンダーであって、塗装を変えた３種類のフェンダーを用意し、検証を行った。フェンダー上に形成される塗装層が、本実施形態における反射制御層２１に相当する。 <Mainstream temperature rise due to reflected light>
In order to verify that the mainstream air can actually be heated by the above-described mechanism, the inventor places the fender of the car in the wind tunnel to imitate the traveling environment of the car and places the fender portion in a state where the air flows. Irradiated with simulated sunlight. Then, it was measured how much the temperature of the air flowing through the site irradiated with the artificial sunlight rises before and after passing through the site. Here, three types of fenders of the same shape and different in painting were prepared and verified. The paint layer formed on the fender corresponds to the reflection control layer 21 in the present embodiment.
　図４は、反射光による主流の温度上昇の検証結果を示すグラフ図である。図４には、検証を行った実験例１～３に係る評価結果が示されており、符号８１は、「スーパーブラック」と呼ばれる標準的な黒色塗装を施した実験例１、符号８２は、「ホワイトパール」と呼ばれる標準的な白色塗装を施した実験例２、符号８３は、「銀メッキ」による銀色塗装を施した実験例３に対応する。実験例１，２，３の順に、紫外線波長から遠赤外線波長までの波長域における平均反射率が大きくなる。 FIG. 4 is a graph showing verification results of the temperature rise of the main flow due to the reflected light. FIG. 4 shows the evaluation results according to experimental examples 1 to 3 for which verification was performed, and reference numeral 81 represents experimental example 1 with a standard black coating called “super black”, and reference numeral 82 represents Experimental example 2 given a standard white paint called "white pearl", numeral 83 corresponds to experimental example 3 given a silver color coating by "silver plating". The average reflectance in the wavelength range from the ultraviolet wavelength to the far infrared wavelength increases in the order of Experimental Examples 1, 2, and 3.
　ここで、「平均反射率」とは、指定された波長域における分光反射率（単色光に対する反射率）の平均値である。すなわち、指定された波長域において、波長の関数である分光反射率を測定し、指定された波長域にわたって測定された分光反射率を平均化して得られる値を「平均反射率」として定義している。 Here, the "average reflectance" is an average value of the spectral reflectance (reflectance for monochromatic light) in a designated wavelength range. That is, the spectral reflectance which is a function of wavelength is measured in a designated wavelength range, and a value obtained by averaging the spectral reflectance measured over the designated wavelength range is defined as “average reflectance”. There is.
　検証では、自動車のフェンダーの表面から表面に対して垂直方向に距離ｄだけ離れた位置であって、空気の流れに沿って、疑似太陽光が照射される部位の上流に熱電対３１ａを配置し、疑似太陽光が照射される部位の下流に熱電対３１ｂを配置した。ここで、フェンダーの表面の境界層よりも外側の主流の中に熱電対が配置されるよう、距離ｄは１８ｍｍに設定された。熱電対３１ａと熱電対３１ｂとは、空気の流れに沿って２００ｍｍの間隔を空けて配置されており、熱電対３１ａと熱電対３１ｂで挟まれる区間に対して、疑似太陽光を照射した。また、フェンダーに対する主流の空気の速度は、風速４０ｋｍ／ｈとした。 In the verification, a thermocouple 31a was placed at a distance d from the surface of the car fender in the direction perpendicular to the surface, along the air flow, upstream of the site to be irradiated with the artificial sunlight. The thermocouple 31b was placed downstream of the site to which the pseudo-sunlight was irradiated. Here, the distance d was set to 18 mm so that the thermocouple was placed in the main flow outside the boundary layer on the surface of the fender. The thermocouple 31a and the thermocouple 31b were disposed at intervals of 200 mm along the flow of air, and the section sandwiched by the thermocouple 31a and the thermocouple 31b was irradiated with simulated sunlight. In addition, the speed of mainstream air to the fender was 40 km / h.
　なお、検証の正確さを期すため、熱電対３１ａと熱電対３１ｂに対して、疑似太陽光が直接照射されることがないよう、注意を払った。熱電対３１ａによって測定される空気の温度は、フェンダーによって反射される疑似太陽光によって暖められる直前の空気の温度であり、熱電対３１ｂによって測定される空気の温度は、フェンダーによって反射される疑似太陽光によって暖められた直後の空気の温度である。 In addition, in order to ensure the accuracy of verification, care was taken so that the artificial sunlight was not directly irradiated to the thermocouples 31a and 31b. The temperature of the air measured by the thermocouple 31a is the temperature of the air just before being warmed by the pseudo-sunlight reflected by the fender, and the temperature of the air measured by the thermocouple 31b is the pseudo-sun reflected by the fender It is the temperature of air just warmed by light.
　図４に示すように、熱電対３１ａで測定した温度よりも熱電対３１ｂで測定した温度の方が高いことが分かった。さらに、実験例１，２，３の順に、温度上昇ΔＴが大きくなることが分かった。すなわち、自動車の表面の塗装の平均反射率が大きいほど、温度上昇ΔＴが大きくなることが分かった。 As shown in FIG. 4, it was found that the temperature measured by the thermocouple 31 b was higher than the temperature measured by the thermocouple 31 a. Furthermore, it turned out that temperature rise (DELTA) T becomes large in order of Experimental example 1,2,3. That is, it was found that the temperature rise ΔT becomes larger as the average reflectance of the paint on the surface of the automobile is larger.
　実際の自動車の全長が４４００ｍｍであるとした場合、自動車の全長にわたっての温度上昇は、図４に示される温度上昇ΔＴの２２倍となる。そのため、実際の自動車であれば、実験例１，２，３の順に、約２Ｋ、約４Ｋ、約６．６Ｋの温度上昇が生じることになる。 Assuming that the total length of the actual car is 4400 mm, the temperature rise over the entire length of the car will be 22 times the temperature rise ΔT shown in FIG. Therefore, in the case of an actual automobile, temperature increases of about 2 K, about 4 K, and about 6.6 K occur in the order of Experimental Examples 1, 2, and 3.
　以上のように、自動車の表面に設けた反射制御層によって光を反射することにより、実際に主流の空気を加熱可能であることが分かった。 As described above, it was found that, by reflecting light by the reflection control layer provided on the surface of the automobile, it is possible to actually heat mainstream air.
　理想気体の状態方程式に当てはめた場合、６．６Ｋの温度上昇によって３００Ｋの空気が３０６．６Ｋになったと仮定すると、約２％の密度低下をもたらす。これは、約２％の空気抵抗Ｆの低減に相当する。 When applied to the ideal gas equation of state, a temperature increase of 6.6 K results in a density loss of about 2%, assuming that 300 K air is 306.6 K. This corresponds to a reduction of the air resistance F of about 2%.
　＜反射制御層の構成＞
　本実施形態では、路面放射を車両の空気抵抗の低減のために利用するため、自動車１の下面に反射制御層２１を設けている。また、所定の波長域にある光の反射率を向上させるため、反射制御層２１に設けた反射増加層２５の厚みを調整している。その態様について次に説明する。 <Configuration of reflection control layer>
In the present embodiment, the reflection control layer 21 is provided on the lower surface of the automobile 1 in order to use the road surface radiation for reducing the air resistance of the vehicle. Further, in order to improve the reflectance of light in a predetermined wavelength range, the thickness of the reflection increasing layer 25 provided in the reflection control layer 21 is adjusted. The aspect will be described next.
　［薄膜での干渉を伴う反射］
　図５は、異なる屈折率の物質によって挟まれた薄膜における光の屈折の様子を示す図である。 [Reflection with interference in thin film]
FIG. 5 is a diagram showing how light is refracted in a thin film sandwiched by substances of different refractive indices.
　図５では、屈折率ｎｍの媒質Ｍ２の上に、厚みｄ、屈折率ｎの薄膜Ｉが形成され、さらに薄膜Ｉの上には屈折率ｎ０の媒質Ｍ１が存在する状況が示されている。そして、媒質Ｍ１の側から薄膜Ｉに向かって波長λの光が、入射角θで入射しているとする。このような状況を考察することは、自動車１の表面に積層された車体塗装層２０、反射制御層２１、空気の間で生じる光の干渉の様子を検討するよいモデルとなる。 In Figure 5, over the medium M2 having a refractive index n m, the thickness d, it is formed a thin film I having a refractive index n, further on the thin film I is shown a situation where there is a medium M1 having a refractive index n 0 There is. Then, it is assumed that light of wavelength λ is incident from the side of the medium M1 toward the thin film I at an incident angle θ. Considering such a situation is a good model for examining the state of light interference generated between the painted body layer 20, the reflection control layer 21 and the air laminated on the surface of the automobile 1.
　媒質Ｍ１と薄膜Ｉの間の境界で反射した光と、薄膜Ｉと媒質Ｍ２の間の境界で反射した光の間に生じる光路差Ｌ（光学的距離の差）は、次の数式２で表される。 The optical path difference L (difference in optical distance) generated between the light reflected at the boundary between the medium M1 and the thin film I and the light reflected at the boundary between the thin film I and the medium M2 is represented by Equation 2 below Be done.
Figure JPOXMLDOC01-appb-M000002
Figure JPOXMLDOC01-appb-M000002
　次に、媒質Ｍ１の側から薄膜Ｉに入射した光が、薄膜Ｉで多重反射した後、再び媒質Ｍ１に反射して戻ってくる場合の強度反射率Ｒを計算する。 Next, the intensity reflectance R in the case where light incident on the thin film I from the side of the medium M1 is multi-reflected by the thin film I and then reflected back to the medium M1 again is calculated.
　媒質Ｍ１から薄膜Ｉへと光が進むときの境界での振幅反射率をｒ１とおき、薄膜Ｉから媒質Ｍ２へと光が進むときの境界での振幅反射率をｒ２とおく。また、媒質Ｍ１の側から薄膜Ｉに入射した光の振幅をＡ０，薄膜Ｉから反射して戻ってくる光の振幅をＡＲとおくと、次の数式３の関係が成り立つことが知られている（ただし、垂直入射の場合（入射角θが０度である場合）を仮定）。 The amplitude reflectance at the boundary when from the medium M1 to film I progresses light r 1 Distant, the amplitude reflectance at the boundary when light travels from a thin film I to the medium M2 is denoted by r 2. Further, it is known that the relationship of the following formula 3 is established, where A 0 is the amplitude of light incident on the thin film I from the side of the medium M 1 and A R is the amplitude of light reflected back from the thin film I (However, assuming the case of normal incidence (when the incident angle θ is 0 degree)).
Figure JPOXMLDOC01-appb-M000003
Figure JPOXMLDOC01-appb-M000003
　ここで、パラメータδは次の数式４で表される。 Here, the parameter δ is expressed by Equation 4 below.
Figure JPOXMLDOC01-appb-M000004
Figure JPOXMLDOC01-appb-M000004
　したがって、強度反射率Ｒは、次の数式５で表される。 Therefore, the intensity reflectance R is expressed by the following equation 5.
Figure JPOXMLDOC01-appb-M000005
Figure JPOXMLDOC01-appb-M000005
　なお、振幅反射率ｒ１及び振幅反射率ｒ２は、次の数式６、数式７のように表される。 The amplitude reflectance r 1 and amplitude reflectance r 2, the following equation 6 is expressed as Equation 7.
Figure JPOXMLDOC01-appb-M000006
Figure JPOXMLDOC01-appb-M000006
Figure JPOXMLDOC01-appb-M000007
Figure JPOXMLDOC01-appb-M000007
　数式５からｒ１及びｒ２を消去するため、数式６及び数式７を数式５に代入して、整頓すると、強度反射率Ｒは、次の数式８で表される。 Substituting Equations 6 and 7 into Equation 5 to eliminate r 1 and r 2 from Equation 5 and arranging them, the intensity reflectance R is expressed by Equation 8 below.
Figure JPOXMLDOC01-appb-M000008
Figure JPOXMLDOC01-appb-M000008
　この強度反射率Ｒは、次の２条件が満たされれば０になる。第一の条件は、振幅条件と呼ばれ、振幅反射率ｒ１と振幅反射率ｒ２が等しくなることである。このとき、屈折率ｎは、屈折率ｎ０と屈折率ｎｍを用いて次の数式９のように表される。 The intensity reflectance R is zero if the following two conditions are satisfied. The first condition is referred to as amplitude condition is that the amplitude reflectance r 1 and amplitude reflectance r 2 equal. At this time, the refractive index n is expressed as the following Expression 9 using the refractive index n 0 and the refractive index n m .
Figure JPOXMLDOC01-appb-M000009
Figure JPOXMLDOC01-appb-M000009
　また、第二の条件は、位相条件と呼ばれ、数式１０のように表される。なお、ｍは０以上の整数である。 Also, the second condition is called a phase condition and is expressed as Equation 10. Here, m is an integer of 0 or more.
Figure JPOXMLDOC01-appb-M000010
Figure JPOXMLDOC01-appb-M000010
　第一の条件は、媒質Ｍ１と薄膜Ｉの間の境界で反射した光と、薄膜Ｉと媒質Ｍ２の間の境界で反射した光の、振幅が一致する条件である。また、第二の条件は、媒質Ｍ１と薄膜Ｉの間の境界で反射した光と、薄膜Ｉと媒質Ｍ２の間の境界で反射した光の間の位相差が、入射する光の半波長の奇数倍であり、ちょうど波の山と谷で打ち消し合う条件である。 The first condition is a condition in which the amplitudes of the light reflected at the boundary between the medium M1 and the thin film I and the light reflected at the boundary between the thin film I and the medium M2 coincide. The second condition is that the phase difference between the light reflected at the boundary between the medium M1 and the thin film I and the light reflected at the boundary between the thin film I and the medium M2 is half the wavelength of the incident light. It is an odd multiple, which is a condition that cancels out at the peaks and valleys of the waves.
　数式４及び数式１０からパラメータδを消去して整頓すると、厚みｄについての、次の数式１１が得られる。 If the parameter δ is eliminated from Equations 4 and 10 and the order is adjusted, the following Equation 11 can be obtained for the thickness d.
Figure JPOXMLDOC01-appb-M000011
Figure JPOXMLDOC01-appb-M000011
　図５に示す状況では、単色光が入射する場合を想定した。しかしながら、実際の反射制御層などの薄膜の設計では、多波長の光が混在した光に対する薄膜の応答を検討する必要がある。上記で導出した強度反射率Ｒは、波長λの光に対する分光反射率とみなせるので、強度反射率Ｒの振る舞いを元に、平均反射率が大きくなる場合と小さくなる場合について検討する。 In the situation shown in FIG. 5, it is assumed that monochromatic light is incident. However, in the design of a thin film such as an actual reflection control layer, it is necessary to examine the response of the thin film to light in which light of multiple wavelengths is mixed. Since the intensity reflectance R derived above can be regarded as a spectral reflectance for light of wavelength λ, cases of increasing and decreasing average reflectance will be examined based on the behavior of the intensity reflectance R.
　一般に波長λは、平均反射率を定義する際の所定の波長域にある任意の値を取りうる。そのため、数式８の右辺第２項の分母に登場する「ｃｏｓ（２δ）」の項は－１から１までの値を取りうる。 In general, the wavelength λ can take any value within a predetermined wavelength range when defining the average reflectance. Therefore, the term “cos (2δ)” appearing in the denominator of the second term on the right side of Formula 8 can take values from −1 to 1.
　「ｃｏｓ（２δ）＝１」を仮定すると、強度反射率Ｒは次の数式１２のＲ１のように表される。 Assuming that “cos (2δ) = 1”, the intensity reflectance R is expressed as R 1 in the following equation 12.
Figure JPOXMLDOC01-appb-M000012
Figure JPOXMLDOC01-appb-M000012
　なお、Ｒ１は、図５において薄膜Ｉが存在せず、媒質Ｍ１と媒質Ｍ２が直接接している場合における媒質Ｍ１と媒質Ｍ２の間の境界での強度反射率に等しい。これは、「ｃｏｓ（２δ）＝１」が、数式４との関係で、薄膜Ｉの厚みｄが０の場合を含んでいることからも理解される。 Incidentally, R 1 is not present film I in FIG. 5, is equal to the intensity reflectance at the boundary between the medium M1 and the medium M2 in the case of the medium M1 and the medium M2 is in direct contact. This is also understood from the fact that “cos (2δ) = 1” includes the case where the thickness d of the thin film I is 0 in relation to Equation (4).
　一方、「ｃｏｓ（２δ）＝－１」を仮定すると、強度反射率Ｒは次の数式１３のＲ２のように表される。 On the other hand, assuming that “cos (2δ) = − 1”, the intensity reflectance R is expressed as R 2 in the following equation 13.
Figure JPOXMLDOC01-appb-M000013
Figure JPOXMLDOC01-appb-M000013
　強度反射率Ｒは、波長λに応じて上述のＲ１からＲ２までの間を振動する関数である。 The intensity reflectance R is a function that oscillates between R 1 and R 2 described above according to the wavelength λ.
　Ｒ１が屈折率ｎに依存しない定数であることに着目すると、薄膜Ｉを設けない場合と比較して、図５に示す状況における平均反射率を大きくするためには、「Ｒ１＜Ｒ２」が満たされるようにすればよい。 Focusing on the fact that R 1 is a constant independent of the refractive index n, in order to increase the average reflectance in the situation shown in FIG. 5 as compared to the case where the thin film I is not provided, “R 1 <R 2 Should be satisfied.
　また、薄膜Ｉを設けない場合と比較して、図５に示す状況における平均反射率を小さくするためには、「Ｒ１＞Ｒ２」が満たされるようにすればよい。 Further, in order to reduce the average reflectance in the situation shown in FIG. 5 as compared with the case where the thin film I is not provided, “R 1 > R 2 ” may be satisfied.
　これらの関係から薄膜Ｉの屈折率ｎについての条件が導出される。 From these relationships, the condition for the refractive index n of the thin film I is derived.
　平均反射率を大きくするための条件式「Ｒ１＜Ｒ２」から、屈折率ｎについての条件を導出すると、「ｎ＞ｎ０かつｎ＞ｎｍ」又は「ｎ＜ｎ０かつｎ＜ｎｍ」となる。 Deriving the condition for the refractive index n from the conditional expression “R 1 <R 2 ” for increasing the average reflectance, “n> n 0 and n> n m ” or “n <n 0 and n <n m .
　平均反射率を小さくするための条件式「Ｒ１＞Ｒ２」から、屈折率ｎについての条件を導出すると、「ｎ０＜ｎ＜ｎｍ」又は「ｎｍ＜ｎ＜ｎ０」となる。 If the condition for the refractive index n is derived from the conditional expression “R 1 > R 2 ” for reducing the average reflectance, “n 0 <n <n m ” or “n m <n <n 0 ” is obtained. .
　特に、平均反射率を小さくするための条件の特別な場合として「Ｒ１＞Ｒ２＝０」とすると、数式９のように屈折率ｎが屈折率ｎ０と屈折率ｎｍの相乗平均に等しい場合が導かれる。 In particular, when "R 1> R 2 = 0" as a special case of the condition for reducing the average reflectance, the geometric mean of the refractive index n m the refractive index n and the refractive index n 0 as in Equation 9 An equal case is introduced.
　さらに、Ｒ２が平均反射率の値を特徴づけていると言えるため、薄膜Ｉの厚みｄについての条件も導出される。 Furthermore, since it can be said that R 2 characterizes the value of the average reflectance, the condition on the thickness d of the thin film I is also derived.
　強度反射率ＲがＲ２の値を取る場合には、「ｃｏｓ（２δ）＝－１」であるため、数式１１が導かれる。平均反射率を定義する波長域が「λｍｉｎ≦λ≦λｍａｘ」であるとすると、数式１１を用いることにより、厚みｄが次の数式１４で示される範囲となることが示される。 When the intensity reflectance R takes a value of R 2 , since “cos (2δ) = − 1”, Formula 11 is derived. Assuming that the wavelength range defining the average reflectance is “λ min ≦ λ ≦ λ max ”, using Equation 11 indicates that the thickness d is in the range represented by Equation 14 below.
Figure JPOXMLDOC01-appb-M000014
Figure JPOXMLDOC01-appb-M000014
　一見すると、ｍは０以上の整数であるため、数式１４は厚みｄについての上限を定めるものではないように見える。しかしながら、ｍの値を必要以上に大きくとった場合、波長域「λｍｉｎ≦λ≦λｍａｘ」の範囲で、強度反射率ＲがＲ１とＲ２の間で振動する回数が増大してしまう。そのため、平均反射率をＲ１に近づけてしまい、薄膜Ｉによる効果を小さくしてしまう。よって、実際の反射制御層などの薄膜の設計では、実用的な屈折率の範囲内で、数式１４によって定められる厚みｄの範囲に実用的な薄膜Ｉの厚みが含まれるよう、ｍの値を選択する。実用的な屈折率の範囲内で許容できるｍの最大値を選択することにより、そのようなｍの下で、数式１４は厚みｄの上限を与えている。 At first glance, because m is an integer greater than or equal to 0, Equation 14 does not seem to set the upper limit for thickness d. However, if the value of m is made larger than necessary, the number of times the intensity reflectance R oscillates between R 1 and R 2 increases in the wavelength range “λ min ≦ λ ≦ λ max ”. . Therefore, the average reflectance approaches R 1 and the effect of the thin film I is reduced. Therefore, in the design of a thin film such as an actual reflection control layer, the value of m is set such that the thickness of the practical thin film I is included in the range of the thickness d determined by Equation 14 within the practical range of refractive index. select. Under such m, Equation 14 gives an upper limit on the thickness d, by choosing the maximum value of m that is acceptable within the practical range of refractive index.
　薄膜Ｉの素材として利用可能な物質としては、種々の物質が想定される。小さい屈折率を有する素材としては、銀（５６３ｎｍにおける屈折率が０．１２）が挙げられる。また、大きい屈折率を有する素材としては、ゲルマニウム（５９０ｎｍにおける屈折率が５．７５）が挙げられる。 As a substance which can be used as a material of the thin film I, various substances are assumed. A material having a small refractive index includes silver (refractive index is 0.12 at 563 nm). Further, as a material having a large refractive index, germanium (refractive index of 5.75 at 590 nm) can be mentioned.
　上述の検討では屈折率は波長に依存しないものとし、さらに、垂直入射の場合を想定した。しかしながら、屈折率が波長に依存する場合や、垂直入射でない場合についても、定性的に上記検討結果を適用することができる。 In the above examination, the refractive index is not dependent on the wavelength, and furthermore, the case of normal incidence is assumed. However, the above examination results can be applied qualitatively even in the case where the refractive index depends on the wavelength or in the case where the normal incidence is not performed.
　［反射制御層に求められる条件］
　図６に示すように、本実施形態では、路面放射（中赤外線および遠赤外線などの、３μｍ以上の長さの波長域の光）を反射する反射制御層２１を自動車下面１１６（移動体下面）に形成している。特に、走行中の自動車１の周りに存在する主流２の加熱に、自動車１に入射する路面放射を利用するため、反射制御層２１は、３μｍ～１００μｍの波長域の光を反射する。 [Conditions Required for Reflection Control Layer]
As shown in FIG. 6, in the present embodiment, a reflection control layer 21 that reflects road surface radiation (light in a wavelength range of 3 μm or more, such as middle infrared rays and far infrared rays) is used as the lower surface 116 of the vehicle (lower surface of moving body). It is formed in. In particular, the reflection control layer 21 reflects light in a wavelength range of 3 μm to 100 μm in order to utilize road surface radiation incident on the automobile 1 for heating the main flow 2 existing around the automobile 1 during traveling.
　また、走行中の自動車１の周りに存在する主流２の加熱の効果が十分に得られるように、３μｍ～１００μｍの波長域における反射制御層２１の平均反射率は、４％以上となっている。 In addition, the average reflectance of the reflection control layer 21 in the wavelength range of 3 μm to 100 μm is 4% or more so that the heating effect of the main flow 2 existing around the traveling automobile 1 can be sufficiently obtained. .
　３μｍ～１００μｍの波長域における平均反射率を４％以上とする方法には、いくつかの方法が考えられる。例えば、図３に示すように、反射制御層２１と空気が直接接している場合には、当該波長域において反射制御層２１の屈折率が所定以上の値になる波長があればよい。 Several methods can be considered as a method of setting the average reflectance to 4% or more in the wavelength range of 3 μm to 100 μm. For example, as shown in FIG. 3, when the reflection control layer 21 is in direct contact with air, it is sufficient if there is a wavelength at which the refractive index of the reflection control layer 21 has a predetermined value or more in the wavelength range.
　具体的には、３μｍ～１００μｍの波長域において、反射制御層２１の屈折率が１．５以上になる波長域があればよい。図５において、媒質Ｍ１を空気、媒質Ｍ２を反射制御層２１とし、薄膜Ｉの厚みｄが０であるとした場合に、空気の屈折率を１として、反射制御層２１の屈折率が１．５以上になる波長に対してＲ１を計算すると、Ｒ１は４％以上になるためである。 Specifically, in a wavelength range of 3 μm to 100 μm, a wavelength range in which the refractive index of the reflection control layer 21 is 1.5 or more is sufficient. In FIG. 5, assuming that the medium M1 is air, the medium M2 is a reflection control layer 21, and the thickness d of the thin film I is 0, the refractive index of air is 1 and the refractive index of the reflection control layer 21 is 1. When R 1 is calculated for a wavelength of 5 or more, R 1 is 4% or more.
　また、例えば、図３に示すように、反射制御層２１と空気が直接接している場合には、当該波長域において反射制御層２１の屈折率が所定以下の値になる波長があればよい。 For example, as shown in FIG. 3, when the reflection control layer 21 and the air are in direct contact with each other, it is sufficient if there is a wavelength at which the refractive index of the reflection control layer 21 has a predetermined value or less in the wavelength range.
　具体的には、３μｍ～１００μｍの波長域において、反射制御層２１の屈折率が０．６６以下になる波長域があればよい。図５において、媒質Ｍ１を空気、媒質Ｍ２を反射制御層２１とし、薄膜Ｉの厚みｄが０であるとした場合に、空気の屈折率を１として、反射制御層２１の屈折率が０．６６以下になる波長に対してＲ１を計算すると、Ｒ１は４％以上になるためである。 Specifically, in the wavelength range of 3 μm to 100 μm, it is sufficient if there is a wavelength range in which the refractive index of the reflection control layer 21 is 0.66 or less. In FIG. 5, when the medium M1 is air, the medium M2 is a reflection control layer 21, and the thickness d of the thin film I is 0, the refractive index of air is 1 and the refractive index of the reflection control layer 21 is 0. When R 1 is calculated for a wavelength of 66 or less, R 1 is 4% or more.
　また、後述するように、反射制御層２１に反射増加層２５を設けた構造とすることで、３μｍ～１００μｍの波長域における平均反射率を４％以上とするものであってもよい。 Further, as described later, by providing the reflection increasing layer 25 in the reflection control layer 21, the average reflectance in the wavelength range of 3 μm to 100 μm may be 4% or more.
　その他にも、自動車下面１１６は路面放射の方向に対して垂直であってもよい。ここで、路面放射の方向とは、路面２００に対して垂直上向きの方向をいう。すなわち、自動車下面１１６、及び、自動車下面１１６に形成された反射制御層２１は路面放射の方向に対して垂直であってもよい（自動車下面１１６に形成された反射制御層２１は路面２００に対して平行であってもよい）。 Alternatively, the under-vehicle surface 116 may be perpendicular to the direction of the road surface radiation. Here, the direction of the road surface radiation refers to a direction that is vertically upward with respect to the road surface 200. That is, the reflection control layer 21 formed on the lower surface 116 of the vehicle and the lower surface 116 of the vehicle may be perpendicular to the direction of the road surface radiation (the reflection control layer 21 formed on the lower surface 116 of the vehicle is Parallel)).
　［反射制御層を設けたことによる効果］
　反射制御層２１は、３μｍ～１００μｍの波長域の光を反射するため、自動車１の表面で反射された光によって、走行中の自動車１の周りに存在する主流２が加熱される。加熱により主流２の密度が低下するため、自動車１の空気抵抗Ｆを低減することができる。 [Effect by providing a reflection control layer]
Since the reflection control layer 21 reflects light in the wavelength range of 3 μm to 100 μm, the light reflected by the surface of the automobile 1 heats the main flow 2 existing around the traveling automobile 1. Since the density of the mainstream 2 is reduced by heating, the air resistance F of the automobile 1 can be reduced.
　特に、自動車下面１１６に形成した反射制御層２１によって路面放射を反射するため、自動車下面１１６と路面２００の間にある主流２を加熱し、主流２の密度を下げることができる。その結果、自動車下面１１６と路面２００の間にある主流２から自動車１が受ける空気抵抗Ｆを低減することができる。 In particular, since the road surface radiation is reflected by the reflection control layer 21 formed on the car lower surface 116, the main stream 2 between the lower car surface 116 and the road surface 200 can be heated to reduce the density of the main stream 2. As a result, it is possible to reduce the air resistance F that the automobile 1 receives from the main flow 2 located between the automobile lower surface 116 and the road surface 200.
　また、３μｍ～１００μｍの波長域における反射制御層２１の平均反射率は、４％以上となっているため、反射制御層２１による路面放射の反射光密度を大きくすることができるため、反射光によって自動車１の空気抵抗Ｆを低減することができる。実際、図４の実験例１で用いた黒色塗装によれば、自動車の全長にわたっての温度上昇は５Ｋ程度となることが別実験によって確かめられている。 Further, since the average reflectance of the reflection control layer 21 in the wavelength range of 3 μm to 100 μm is 4% or more, the reflected light density of the road surface radiation by the reflection control layer 21 can be increased. The air resistance F of the automobile 1 can be reduced. In fact, according to the black coating used in Experimental Example 1 of FIG. 4, it has been confirmed by another experiment that the temperature rise over the entire length of the vehicle is about 5K.
　さらに、自動車下面１１６が路面放射の方向に対して垂直、もしくは、垂直に近い角度を有することによって、反射制御層２１による路面放射の反射光密度を大きくする効果がより大きくなる。これは、反射制御層２１と路面２００の間における「路面放射の閉じ込め現象」が生じるためである。 In addition, the lower surface 116 of the automobile has an angle perpendicular to or nearly perpendicular to the direction of the road surface radiation, the effect of increasing the reflected light density of the road surface radiation by the reflection control layer 21 is further enhanced. This is because "the phenomenon of confinement of road surface radiation" occurs between the reflection control layer 21 and the road surface 200.
　「路面放射の閉じ込め現象」とは、自動車下面１１６で反射された路面放射が、再度、路面２００によって吸収・反射されることをいう。当該効果により、自動車下面１１６で反射された路面放射は、再度、路面２００によって吸収・反射され、自動車下面１１６と路面２００の間にある主流２の加熱のために再利用できる。自動車下面１１６と路面２００の間にある主流２は、路面２００からの路面放射、および、反射制御層２１による反射光によって加熱されるため、空気抵抗Ｆを低減する効果が増大する。 “Containment phenomenon of road surface radiation” means that road surface radiation reflected by the lower surface 116 of the automobile is absorbed and reflected by the road surface 200 again. By the effect, the road surface radiation reflected by the lower surface 116 of the car is again absorbed and reflected by the road surface 200 and can be reused to heat the main flow 2 located between the lower surface 116 of the car and the road surface 200. The mainstream 2 located between the lower surface 116 of the vehicle and the road surface 200 is heated by the road surface radiation from the road surface 200 and the reflected light from the reflection control layer 21, so the effect of reducing the air resistance F is increased.
（第２実施形態）
　本発明の第２実施形態に係る自動車は、反射増加層２５を備える点で第１実施形態と異なる。第２実施形態において説明しない他の構成、作用及び効果は、第１実施形態と実質的に同様であるので重複する説明を省略する。 Second Embodiment
The vehicle according to the second embodiment of the present invention differs from the first embodiment in that a reflection enhancing layer 25 is provided. The other configurations, operations, and effects not described in the second embodiment are substantially the same as those in the first embodiment, and thus redundant description will be omitted.
　図７は、本実施形態に係る自動車の表面の構造を示す拡大断面図である。図７に示すように、自動車１の表面には車体塗装層２０が形成され、さらに車体塗装層２０の上に反射制御層２１が形成されている。そして、反射制御層２１には、３μｍ～１００μｍの波長域での光を反射するための反射増加層２５が設けられている。 FIG. 7 is an enlarged sectional view showing the structure of the surface of the vehicle according to the present embodiment. As shown in FIG. 7, a car body coating layer 20 is formed on the surface of the automobile 1, and a reflection control layer 21 is further formed on the car body coating layer 20. The reflection control layer 21 is provided with a reflection increasing layer 25 for reflecting light in a wavelength range of 3 μm to 100 μm.
　ここで、反射制御層２１に反射増加層２５を設ける態様としては、反射制御層２１の上に反射増加層２５を積層する態様や、反射制御層２１によって反射増加層２５を挟み込む態様（いわゆる多層構造）、その他にも、反射制御層２１自体を反射増加層２５とする態様など、種々の態様が考えられる。以下では、反射制御層２１の上に反射増加層２５を積層する態様について説明する。以下では説明しない態様においても、同様の効果が得られる。 Here, as an embodiment in which the reflection increasing layer 25 is provided on the reflection control layer 21, an embodiment in which the reflection increasing layer 25 is laminated on the reflection control layer 21 or an embodiment in which the reflection increasing layer 25 is sandwiched by the reflection control layer 21 In addition to the above, various aspects can be considered, such as an aspect in which the reflection control layer 21 itself is the reflection enhancing layer 25. Below, the aspect which laminates | stacks the reflection increase layer 25 on the reflection control layer 21 is demonstrated. The same effect can be obtained also in an embodiment which will not be described below.
　［反射増加層に求められる条件］
　本実施形態では、路面放射を反射するための反射増加層２５を反射制御層２１の上に積層している。特に、走行中の自動車１の周りに存在する主流２の加熱に路面放射を利用するため、３μｍ～１００μｍの波長域にある光に対する反射増加層２５の平均反射率が高くなるように形成している。以下では、反射増加層２５が、３μｍ～１００μｍの波長域にある光を反射するための条件を検討する。 [Requirements for reflection increasing layer]
In the present embodiment, a reflection increasing layer 25 for reflecting road surface radiation is laminated on the reflection control layer 21. In particular, in order to use the road surface radiation to heat the main flow 2 existing around the traveling automobile 1, it is formed so that the average reflectance of the reflection enhancing layer 25 to light in the wavelength range of 3 .mu.m to 100 .mu.m is high. There is. In the following, conditions under which the reflection enhancing layer 25 reflects light in a wavelength range of 3 μm to 100 μm will be examined.
　本実施形態では、図５に示す薄膜Ｉ、媒質Ｍ１、媒質Ｍ２に対して、反射増加層２５、空気、反射制御層２１（車体側物質）が、それぞれ対応している。 In the present embodiment, the thin film I, the medium M1, and the medium M2 shown in FIG. 5 correspond to the reflection increasing layer 25, the air, and the reflection control layer 21 (the vehicle-side material), respectively.
　反射増加層２５を設けない場合と比較して、３μｍ～１００μｍの波長域における＊２５の平均反射率を大きくするためには、条件式「Ｒ１＜Ｒ２」が満たされればよい。そのため、先の検討に基づき、３μｍ～１００μｍの波長域において、反射制御層２１（車体側物質）の屈折率および空気の屈折率の両方より大きい屈折率を有する素材で反射増加層２５は形成されていればよい。もしくは、３μｍ～１００μｍの波長域において、反射制御層２１（車体側物質）の屈折率および空気の屈折率の両方より小さい屈折率を有する素材で、反射増加層２５は形成されていればよい。 In order to increase the average reflectance of * 25 in the wavelength range of 3 μm to 100 μm as compared with the case where the reflection increasing layer 25 is not provided, the conditional expression “R 1 <R 2 ” may be satisfied. Therefore, based on the previous study, in the wavelength range of 3 μm to 100 μm, the reflection increasing layer 25 is formed of a material having a refractive index larger than both of the refractive index of the reflection control layer 21 (body side material) and the refractive index of air. It should just be. Alternatively, the reflection increasing layer 25 may be formed of a material having a refractive index smaller than both of the refractive index of the reflection control layer 21 (body-side material) and the refractive index of air in a wavelength range of 3 μm to 100 μm.
　すなわち、反射増加層２５の屈折率は、３μｍ～１００μｍの波長域において、反射制御層２１（車体側物質）の屈折率と空気の屈折率で挟まれる範囲の外の値を有している。 That is, the refractive index of the reflection increasing layer 25 has a value outside the range between the refractive index of the reflection control layer 21 (the vehicle-side material) and the refractive index of air in the wavelength range of 3 μm to 100 μm.
　なお、反射増加層２５を自動車１の表面に形成する場合には、製造の容易さや品質確保の観点から、反射増加層２５の厚みの範囲は「２０μｍ～４０μｍ」程度であることが望ましい。 When the reflection increasing layer 25 is formed on the surface of the automobile 1, the thickness of the reflection increasing layer 25 is preferably in the range of about 20 μm to 40 μm from the viewpoint of easiness of production and securing of quality.
　数式１４において「λｍｉｎ＝３μｍ」、「λｍａｘ＝１００μｍ」とし、実用的な屈折率ｎの範囲（０．１２≦ｎ≦５．７５）で、数式１４が厚みの範囲「２０μｍ～４０μｍ」を含むような最大のｍを求めると、ｍ＝５となる。 In Equation 14, “λ min = 3 μm” and “λ max = 100 μm”, and in a practical range of refractive index n (0.12 ≦ n ≦ 5.75), Equation 14 has a thickness range of “20 μm to 40 μm” If we find the largest m that contains n, then m = 5.
　よって、反射増加層２５の厚みは、７５０ｎｍを反射増加層２５の屈折率ｎで除した値以上であって、２７５０００ｎｍを反射増加層２５の屈折率ｎで除した値以下であることが望ましい。 Therefore, it is preferable that the thickness of the reflection increasing layer 25 is equal to or more than 750 nm divided by the refractive index n of the reflection increasing layer 25 and equal to or less than 275000 nm divided by the refractive index n of the reflection increasing layer 25.
　［反射増加層を設けたことによる効果］
　反射増加層２５の屈折率が、反射制御層２１（車体側物質）の屈折率と空気の屈折率で挟まれる範囲の外の値となっているため、反射増加層２５を設けない場合と比較して、反射増加層２５の存在により自動車１の表面の３μｍ～１００μｍの波長域における平均反射率が大きくなっている。そのため、路面２００からの路面放射を効率よく反射することができる。その結果、自動車１の表面で反射された光によって、走行中の自動車１の周りに存在する主流２が加熱される。加熱により主流２の密度が低下するため、自動車１の空気抵抗Ｆを低減することができる。 [Effect of providing a reflection increasing layer]
Since the refractive index of the reflection increasing layer 25 is a value outside the range between the refractive index of the reflection control layer 21 (body-side material) and the refractive index of air, comparison with the case where the reflection increasing layer 25 is not provided The average reflectance in the 3 μm to 100 μm wavelength region of the surface of the automobile 1 is increased by the presence of the reflection enhancing layer 25. Therefore, the road surface radiation from the road surface 200 can be efficiently reflected. As a result, the light reflected by the surface of the automobile 1 heats the main flow 2 existing around the traveling automobile 1. Since the density of the mainstream 2 is reduced by heating, the air resistance F of the automobile 1 can be reduced.
　また、３μｍ～１００μｍの波長域に基づいて、数式１４によって定まる厚みの範囲に収まるように反射増加層２５の厚みを調整し、反射増加層２５の厚みを、７５０ｎｍを反射増加層２５の屈折率ｎで除した値以上であって、２７５０００ｎｍを反射増加層２５の屈折率ｎで除した値以下としている。そのため、３μｍ～１００μｍの波長域における平均反射率が最大化される。その結果、路面放射の反射光によって自動車１の空気抵抗Ｆを低減することができる。 Further, based on the wavelength range of 3 μm to 100 μm, the thickness of the reflection increasing layer 25 is adjusted so as to fall within the thickness range determined by Equation 14, and the thickness of the reflection increasing layer 25 is 750 nm. The value is equal to or greater than the value divided by n and equal to or less than the value divided by the refractive index n of the reflection increasing layer 25 at 275,000 nm. Therefore, the average reflectance in the wavelength range of 3 μm to 100 μm is maximized. As a result, the air resistance F of the automobile 1 can be reduced by the reflected light of the road surface radiation.
　また、より確実に平均反射率を大きくして、反射光による加熱で自動車１の空気抵抗Ｆを低減する効果を得るため、反射増加層２５の屈折率は、反射制御層２１（車体側物質）の屈折率の１．０１倍以上、かつ、空気の屈折率の１．０１倍以上であるようにしてもよい。同様に、反射増加層２５の屈折率は、反射制御層２１（車体側物質）の屈折率の０．９９倍以下、かつ、空気の屈折率の０．９９倍以下であるようにしてもよい。 In addition, the refractive index of the reflection increasing layer 25 is the reflection control layer 21 (body-side material) in order to obtain the effect of more reliably increasing the average reflectance and reducing the air resistance F of the automobile 1 by heating by reflected light. The refractive index of the optical system of the present invention may be 1.01 times or more of the refractive index of the light emitting element and 1.01 times or more of the refractive index of air. Similarly, the refractive index of the reflection increasing layer 25 may be 0.99 times or less of the refractive index of the reflection control layer 21 (body-side material) and 0.99 times or less of the refractive index of air. .
　なお、反射増加層２５の屈折率と反射制御層２１（車体側物質）の屈折率の差、および、反射増加層２５の屈折率と空気の屈折率の差が、大きくなればなるほど、平均反射率はより大きくなる。そのため、上記条件を満たしつつ、実用的な屈折率の範囲で、反射制御層２１（車体側物質）の屈折率および空気の屈折率の両方よりも反射増加層２５の屈折率をできる限り大きくするか、あるいは、反射制御層２１（車体側物質）の屈折率および空気の屈折率の両方よりもできる限り小さくすることが望ましい。 The larger the difference between the refractive index of the reflection increasing layer 25 and the refractive index of the reflection control layer 21 (body-side material), and the difference between the refractive index of the reflection increasing layer 25 and the refractive index of air, the average reflection The rate will be greater. Therefore, the refractive index of the reflection increasing layer 25 is made as large as possible both of the refractive index of the reflection control layer 21 (body-side material) and the refractive index of air within the practical refractive index range while satisfying the above conditions. Alternatively, it is desirable that the refractive index of the reflection control layer 21 (body-side material) and the refractive index of air be as small as possible.
　［反射増加層の水平からの角度との関係］
　上記の説明では、反射増加層２５に対して光が垂直に入射する場合を想定していた。実際には、反射増加層２５に対して光が垂直に入射するとは限らない。しかしながら、反射増加層２５に対して光がほぼ垂直に入射しない場合であっても、同じ作用効果を得ることができる。 [Relationship of the reflection increasing layer with the angle from the horizontal]
In the above description, it is assumed that light is perpendicularly incident on the reflection increasing layer 25. In fact, light does not always enter perpendicularly to the reflection enhancing layer 25. However, even when the light is not incident substantially perpendicularly to the reflection enhancing layer 25, the same effect can be obtained.
　同じ作用効果を得ることができることを、図８Ａ、図８Ｂ、図９を用いて説明する。図８Ａは、本実施形態に係る自動車の下面に対する、路面放射の入射角を説明する側面図である。図８Ｂは、本実施形態に係る自動車の下面に対する、路面放射の入射角を説明する正面図である。また、図９は、光の入射角と反射増加層の厚みの関係を示すグラフ図である。 The fact that the same action and effect can be obtained will be described with reference to FIGS. 8A, 8B, and 9. FIG. 8A is a side view for explaining the incident angle of the road surface radiation with respect to the lower surface of the vehicle according to the present embodiment. FIG. 8B is a front view illustrating the incident angle of the road surface radiation with respect to the lower surface of the automobile according to the present embodiment. FIG. 9 is a graph showing the relationship between the incident angle of light and the thickness of the reflection increasing layer.
　図８Ａ、図８Ｂに示すように、路面２００から路面放射が自動車下面１１６に入射している状況を考える。この場合、自動車１の進行方向に対して水平になる部分（以下、水平箇所）の反射増加層２５に対しては、路面放射は垂直に入射する。しかし、その他、タイヤハウジングと自動車１の中央部分をつなぐ面など、自動車下面１１６には自動車１の進行方向に対して水平ではない部分（以下、傾斜箇所）が存在し得る。傾斜箇所において、反射増加層２５に対して光は垂直に入射しない。傾斜箇所の水平からの傾き角度をθとすると、傾斜箇所に対して路面放射の入射角はθとなる。 As shown to FIG. 8A and FIG. 8B, the condition where road surface radiation is incident on the undersurface 116 of a car from the road surface 200 is considered. In this case, the road surface radiation is perpendicularly incident on the reflection increasing layer 25 in a portion (hereinafter, a horizontal portion) horizontal to the traveling direction of the automobile 1. However, there may be a portion (hereinafter referred to as an inclined portion) which is not horizontal with respect to the traveling direction of the automobile 1, such as a surface connecting the tire housing and the central portion of the automobile 1. The light does not perpendicularly enter the reflection enhancing layer 25 at the inclined portion. Assuming that the inclination angle from the horizontal of the inclined portion is θ, the incident angle of the road surface radiation with respect to the inclined portion is θ.
　入射角θが０度から大きくなって９０度に近づくにつれ、数式２の平方根の部分の大きさが小さくなる。光路差Ｌが、水平箇所の反射増加層２５と傾斜箇所の反射増加層２５において同じであれば、水平箇所と傾斜箇所とで同じ平均反射率が実現されることに着目すると、図９に示すように、入射角θが０度から大きくなって９０度に近づくにつれ、傾斜箇所の反射増加層２５の厚みｄを大きくする必要がある。 As the incident angle θ increases from 0 ° and approaches 90 °, the size of the square root of Equation 2 decreases. If the optical path difference L is the same in the reflection increasing layer 25 at the horizontal portion and the reflection increasing layer 25 at the inclined portion, focusing on the fact that the same average reflectance is realized at the horizontal portion and the inclined portion, as shown in FIG. Thus, as the incident angle θ increases from 0 ° and approaches 90 °, it is necessary to increase the thickness d of the reflection increasing layer 25 at the inclined portion.
　よって、水平箇所と同様に傾斜箇所での平均反射率を大きくするためには、水平箇所の反射増加層２５の厚みに比べて、傾斜箇所の反射増加層２５の厚みを大きくしてやればよい。また、傾き角度θが大きくなればなるほど、傾斜箇所の反射増加層２５の厚みを大きくしてやればよい。 Therefore, in order to increase the average reflectance at the inclined portion as in the case of the horizontal portion, the thickness of the reflection increasing layer 25 at the inclined portion may be increased as compared with the thickness of the reflection increasing layer 25 at the horizontal portion. Further, as the inclination angle θ becomes larger, the thickness of the reflection increasing layer 25 at the inclined portion may be increased.
　このように、傾斜箇所の反射増加層２５の厚みを、傾き角度に応じて調整することにより、傾斜箇所の反射増加層２５も、路面放射を効率よく反射することができる。その結果、反射光によって自動車１の空気抵抗Ｆを低減することができる。 As described above, by adjusting the thickness of the reflection increasing layer 25 at the inclined portion according to the inclination angle, the reflection increasing layer 25 at the inclined portion can also efficiently reflect the road surface radiation. As a result, the air resistance F of the automobile 1 can be reduced by the reflected light.
　上述の各実施形態では、移動体が自動車である場合を挙げて説明したが、自動車の他にも、空気中を運動する移動体に対して本発明は適用可能である。移動体の例としては、自動車の他に、二輪車、鉄道、航空機、ロケットなどが挙げられる。 In the above-described embodiments, although the case where the moving body is a car has been described, the present invention is applicable to a moving body that moves in the air besides the car. Examples of mobile objects include motorcycles, railways, aircrafts, rockets, etc. in addition to automobiles.
　以上、実施形態に沿って本発明の内容を説明したが、本発明はこれらの記載に限定されるものではなく、種々の変形及び改良が可能であることは、当業者には自明である。この開示の一部をなす論述および図面は本発明を限定するものであると理解すべきではない。この開示から当業者には様々な代替実施形態、実施例および運用技術が明らかとなろう。 Although the contents of the present invention have been described above according to the embodiments, the present invention is not limited to these descriptions, and it is obvious for those skilled in the art that various modifications and improvements are possible. It should not be understood that the statements and drawings that form a part of this disclosure limit the present invention. Various alternative embodiments, examples and operation techniques will be apparent to those skilled in the art from this disclosure.
　本発明はここでは記載していない様々な実施形態等を含むことは勿論である。したがって、本発明の技術的範囲は上記の説明から妥当な請求の範囲に係る発明特定事項によってのみ定められるものである。 Of course, the present invention includes various embodiments that are not described herein. Accordingly, the technical scope of the present invention is defined only by the invention-specifying matters according to the claims that are appropriate from the above description.
　１　　自動車（移動体）
　２　　主流
　２０　車体塗装層
　２１　反射制御層
　２５　反射増加層
　４１　境界層
　４２　境界
　４３　外部領域
　１１６　自動車下面（移動体下面） 1 Car (mobile)
2 Main stream 20 Body paint layer 21 Reflection control layer 25 Reflection increasing layer 41 Boundary layer 42 Boundary 43 External area 116 Automobile lower surface (mobile body lower surface)

Claims (9)

  1. 　路面放射の波長域にある光を反射する反射制御層が、路面に対向する移動体下面に形成された移動体であって、
    　前記反射制御層は、３μｍから１００μｍまでの波長域にある光を反射すること
    を特徴とする移動体。     A reflection control layer that reflects light in a wavelength range of road surface radiation is a moving body formed on the lower surface of the moving body facing the road surface,
    The mobile body characterized in that the reflection control layer reflects light in a wavelength range of 3 μm to 100 μm.
  2. 　請求項１に記載された移動体であって、
    　３μｍから１００μｍまでの波長における前記反射制御層の平均反射率が、４％以上であること
    を特徴とする移動体。     A mobile unit according to claim 1, wherein
    An average reflectance of the reflection control layer at a wavelength of 3 μm to 100 μm is 4% or more.
  3. 　請求項１又は２に記載された移動体であって、
    　前記反射制御層に反射増加層を設け、
    　３μｍから１００μｍまでの波長域において、
    　　前記反射増加層の屈折率は、前記反射増加層の下にある車体側物質の屈折率と空気の屈折率で挟まれる範囲の外の値であり、
    　　前記反射増加層の厚みは、７５０ｎｍを前記反射増加層の屈折率で除した値以上、かつ、２７５０００ｎｍを前記反射増加層の屈折率で除した値以下であること
    を特徴とする移動体。     A mobile unit according to claim 1 or 2, wherein
    Providing a reflection increasing layer on the reflection control layer;
    In the wavelength range from 3 μm to 100 μm,
    The refractive index of the reflection increasing layer is a value outside the range between the refractive index of the vehicle-side material below the reflection increasing layer and the refractive index of air,
    The movable body characterized in that the thickness of the reflection increasing layer is not less than a value obtained by dividing 750 nm by the refractive index of the reflection increasing layer and not more than a value obtained by dividing 275000 nm by the refractive index of the reflection increasing layer.
  4. 　請求項３に記載された移動体であって、
    　３μｍから１００μｍまでの波長域において、
    　　前記反射増加層の屈折率は、前記車体側物質の屈折率および空気の屈折率の両方よりも大きいこと
    を特徴とする移動体。     A mobile unit according to claim 3, wherein
    In the wavelength range from 3 μm to 100 μm,
    The movable body characterized in that the refractive index of the reflection enhancing layer is larger than both of the refractive index of the body side material and the refractive index of air.
  5. 　請求項４に記載された移動体であって、
    　３μｍから１００μｍまでの波長域において、
    　　前記反射増加層の屈折率は、前記車体側物質の屈折率の１．０１倍以上、かつ、前記空気の屈折率の１．０１倍以上であること
    を特徴とする移動体。     A mobile unit according to claim 4, wherein
    In the wavelength range from 3 μm to 100 μm,
    The movable body characterized in that the refractive index of the reflection increasing layer is 1.01 or more times the refractive index of the vehicle-body-side material and 1.01 or more times the refractive index of the air.
  6. 　請求項３に記載された移動体であって、
    　３μｍから１００μｍまでの波長域において、
    　　前記反射増加層の屈折率は、前記車体側物質の屈折率および空気の屈折率の両方よりも小さいこと
    を特徴とする移動体。     A mobile unit according to claim 3, wherein
    In the wavelength range from 3 μm to 100 μm,
    The movable body characterized in that the refractive index of the reflection enhancing layer is smaller than both of the refractive index of the body-side material and the refractive index of air.
  7. 　請求項６に記載された移動体であって、
    　　前記反射増加層の屈折率は、前記車体側物質の屈折率の０．９９倍以下、かつ、前記空気の屈折率の０．９９倍以下であること
    を特徴とする移動体。     A mobile unit according to claim 6, wherein
    The movable body characterized in that the refractive index of the reflection increasing layer is 0.99 times or less of the refractive index of the vehicle body side material and 0.99 times or less of the refractive index of the air.
  8. 　請求項３乃至７のいずれか一項に記載された移動体であって、
    　前記移動体下面の水平からの傾き角度が大きくなるほど、前記反射増加層の厚みを大きくすること
    を特徴とする移動体。     A mobile unit according to any one of claims 3 to 7, wherein
    The movable body characterized in that the thickness of the reflection increasing layer is increased as the inclination angle of the lower surface of the movable body from the horizontal is increased.
  9. 　請求項１乃至７のいずれか一項に記載された移動体であって、
    　前記移動体下面は、前記路面放射の方向に対して垂直であること
    を特徴とする移動体。     A mobile object according to any one of claims 1 to 7, wherein
    The movable body, wherein the lower surface of the movable body is perpendicular to the direction of the road surface radiation.
PCT/JP2017/029283 2017-08-14 2017-08-14 Mobile body having reflection control layer WO2019035158A1 (en)

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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2000043758A (en) * 1998-07-29 2000-02-15 Nissan Shatai Co Ltd Heat insulating panel for vehicle and heat insulating paint for vehicle
JP2005112108A (en) * 2003-10-07 2005-04-28 Nissan Motor Co Ltd Heat function structure for automobile

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2000043758A (en) * 1998-07-29 2000-02-15 Nissan Shatai Co Ltd Heat insulating panel for vehicle and heat insulating paint for vehicle
JP2005112108A (en) * 2003-10-07 2005-04-28 Nissan Motor Co Ltd Heat function structure for automobile

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