Roof structure

Abstract

To provide a roof structure capable of suppressing an increase in temperature in a vehicle cabin with a further enhanced radiation cooling performance.SOLUTION: A roof structure includes a roof panel of a vehicle, and a roof trim arranged on a vehicle cabin side of the roof panel. The roof panel includes a radiation cooling layer that is arranged on an outside surface and radiates far-infrared ray toward to the outside of the vehicle. The roof trim includes an attachment / detachment portion having a sunshade function at a part thereof. The attachment / detachment portion can be fixed along an inner surface of a glass pane of the vehicle.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a roof structure, and more particularly, to a roof structure capable of further enhancing radiative cooling performance and suppressing the temperature rise in the passenger compartment.

Background Art

[0002] Patent Document 1 discloses a vehicle sun visor that can secure a head clearance when not in use with a simple structure, expand the interior space while suppressing weight increase and manufacturing costs. This vehicle sun visor is provided with a notch hole in a roof lining disposed on the ceiling portion of the passenger compartment, a light-shielding panel that can be stored in the notch hole, pivot support means for pivotally supporting the front edge or side edge of the light-shielding panel to the edge of the notch hole, and fixing means for fixing the light-shielding panel in the notch hole in a state where the light-shielding panel is stored in the notch hole.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in a vehicle sun visor as disclosed in Patent Document 1, for example, only a part of the solar radiation from the front windshield to the passenger compartment can be blocked, and there is a problem that the effect of suppressing the temperature rise in the passenger compartment is limited.

[0005] The present invention has been made in view of such problems of the prior art, and an object thereof is to provide a roof structure capable of further enhancing radiative cooling performance and suppressing the temperature rise in the passenger compartment.

Means for Solving the Problems

[0006] As a result of intensive studies to achieve the above object, the inventors of the present invention have found that the object can be achieved by providing a roof panel having a predetermined radiation cooling layer, and having a detachable portion in a part of the roof trim that has a sunshade function and can be fixed along the inner surface of the window glass of the vehicle, and thus have completed the present invention.

[0007] That is, the roof structure of the present invention includes a roof panel of a vehicle and a roof trim disposed on the passenger compartment side thereof. The roof panel has a radiation cooling layer disposed on its outer surface and radiating far-infrared rays toward the outside of the vehicle. The roof trim has a detachable portion having a sunshade function in a part thereof. The detachable portion can be fixed along the inner surface of the window glass of the vehicle.

Advantages of the Invention

[0008] According to the present invention, since the roof panel having the above-described radiation cooling layer is provided, and the roof trim has a detachable portion having a sunshade function in a part thereof and can be fixed along the inner surface of the window glass of the vehicle, it is possible to provide a roof structure that can further enhance the radiation cooling performance and suppress the temperature rise in the passenger compartment.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0010] Hereinafter, some embodiments of the roof structure of the present invention will be described in detail with reference to the drawings. Note that the dimensional ratios of the drawings cited below are exaggerated for convenience of explanation and may be different from the actual ratios.

[0011] (First Embodiment) FIG. 1 is a side view schematically showing a part of a vehicle to which the roof structure of the present embodiment is applied, namely, the vicinity of the front windshield and the roof panel. Also, the upper view of FIG. 2 is a cross-sectional view showing the attached state of the attachment / detachment part in the A part and the B part of the roof structure of the present embodiment, and the lower view of FIG. 2 is a cross-sectional view showing the detached state of the attachment / detachment part in the A part and the B part of the roof structure of the present embodiment.

[0012] As shown in FIGS. 1 and 2, the roof structure 1 of the present embodiment includes a roof panel 10 of a vehicle 50 and a roof trim 20 disposed on the vehicle compartment 50a side thereof. The roof panel 10 has a radiation cooling layer 11 disposed on its outer surface and radiating far-infrared rays toward the outside of the vehicle 50. The roof trim 20 has an attachment / detachment part 21 having a sunshade function in a part thereof. The attachment / detachment part 21 can be fixed along the inner surface of the window glass (front windshield in the illustrated example) 51 of the vehicle 50.

[0013] Here, examples of the roof panel 10 include those formed of a plate material such as conventionally known stainless steel, aluminum alloy, carbon fiber reinforced resin, etc. Note that the roof panel may be a sunroof.

[0014] The radiative cooling layer 11 has the property of emitting electromagnetic waves and lowering its temperature when exposed to sunlight. The wavelength range of the electromagnetic waves emitted by the radiative cooling layer is a wavelength range called the "atmospheric window" where the influence of the atmosphere is small and the light transmittance is high, for example, infrared rays from 7 μm to 13 μm and from 16 μm to 30 μm. Since the absorption rate of infrared rays in this wavelength range by the atmosphere is low, when irradiated from near the ground surface towards the sky, it can propagate to outer space. The radiative cooling layer 11 can receive sunlight with wavelengths from 0.3 μm to 3 μm and irradiate infrared rays in the atmospheric window, thereby releasing thermal energy into outer space. Examples of materials for forming such a radiative cooling layer include, for example, SPACECOOL (manufactured by SPACECOOL), films and paints manufactured by Radi-Cool, etc.

[0015] The cooling effect by such a radiative cooling layer is represented by the following formula (1) called, for example, Stefan-Boltzmann's law. I = εσ(λ)(T 4 - T0 4 )…(1) In formula (1), I: radiative energy, ε: Stefan-Boltzmann constant, σ(λ): emissivity, T: object temperature, T0: environmental temperature

[0016] The object temperature T is, for example, the temperature of a vehicle directly irradiated by sunlight. The environmental temperature T0 is the temperature of the universe, for example, -264 °C. As shown in formula (1), according to the radiative cooling layer, the radiative cooling effect increases in proportion to the fourth power of the temperature. The higher the object temperature T, that is, the higher the temperature of the vehicle 2, the greater the radiative cooling effect.

[0017] The radiative cooling layer as described above typically has a reflective layer, a polymer layer laminated on this reflective layer facing the atmosphere, and a plurality of particles dispersed inside this polymer layer.

[0018] Examples of the reflective layer include metal thin films such as silver (Ag) or aluminum (Al). Light incident on the light-receiving surface (the surface facing the atmosphere) of the polymer layer passes through the polymer layer, is reflected by the reflective layer, and then passes through the polymer layer again. The thickness of the reflective layer is not particularly limited, but is, for example, 30 nm or more and 1000 nm or less. As an example of the reflective layer, a silver thin film with a thickness of 200 nm may be used.

[0019] Examples of the polymer layer include any one or more of polyolefin, polymethyl methacrylate (PMMA), polymethylpentene (PMP, also known as 4-methylpentene-1 and poly(4-methyl-1-pentene)), polyethylene (PE), polystyrene (PS), polyethylene terephthalate (PET), polycarbonate (PC), polytetrafluoroethylene (PTFE), combinations thereof, and copolymers thereof. Alternatively, the polymer layer 42 may be composed of PMDS. PMDS is a type of silicone called polydimethylsiloxane. The thickness of the polymer layer only needs to be greater than the diameter of the dispersed particles, and is, for example, 4 μm or more and 1000 μm or less. As an example of the polymer layer, polymethylpentene with a thickness of 50 μm may be used.

[0020] The dispersed particles are composed of, for example, any one or more of silicon dioxide (silica, SiO2), calcium carbonate (CaCO3), silicon carbide (SiC), zinc oxide (ZnO), titanium dioxide (TiO2), and alumina (Al2O3). These particles may be spherical or non-spherical. The diameter of these particles (when the particles are non-spherical, the effective diameter or characteristic dimension) only needs to be smaller than the thickness of the polymer layer, and is, for example, 1 μm or more and 30 μm or less. As an example of such particles, silica spheres with a diameter of 8 μm may be used. The volume concentration of the particles in the polymer layer is, for example, 1% or more and 25% or less. In the polymer layer, silica spheres with a diameter of 8 μm may be dispersed at a volume concentration of 6%.

[0021] The layer containing the polymer layer and the dispersed particles as described above has one or more absorption bands in the wavelength range of the atmospheric window, is transparent or substantially transparent to sunlight from 0.3 μm to 3 μm, and has a high infrared emissivity in the atmospheric window.

[0022] As shown in FIGS. 1 and 2, the film-shaped radiative cooling layer 11 as described above is wrapped around the outer surface of the vehicle 50, and is wrapped around, for example, the roof panel 10 where direct sunlight is strong. Among the above-described reflective layers, the surface on the opposite side of the bonding surface with the polymer layer is attached to the vehicle 50 via an adhesive (not shown). By film wrapping, it is easy to attach the radiative cooling layer 11 to the vehicle 50. Note that the radiative cooling layer 11 may be a coating film applied to the outer surface of the vehicle 50 (for example, the roof panel 10, etc.) instead of being in the form of a film. In the case of a coating film, the radiative cooling layer 11 is composed of a polymer and a large number of dispersed particles as described above. The surface to be coated (for example, the outer surface of the roof panel 10) functions as the above-described reflective layer. Also in the case of coating, it is easy to attach the radiative cooling layer 11 to the vehicle 50.

[0023] Typically, a conventionally known roof trim can be used for the roof trim 20. Further, as the detachable site 21, for example, a portion of the roof trim 20 where a room lamp or the like is not attached can be used. Although not shown, the detachable site 21 has a structure that can be fixed to other portions of the roof trim 20.

[0024] Also, in the illustrated example, the detachable site 21 is provided with a fixing member 30 that enables the detachable site 21 to be fixed along the inner surface of the window glass 51 of the vehicle 50. Examples of such a fixing member 30 include suction cups made of rubber or resin.

[0025] Furthermore, as shown in the illustrated example, it is preferable that the roof structure 1 further includes an airflow generating device 40 disposed in the roof trim back space 20b between the roof panel 10 and the roof trim 20. Examples of such an airflow generating device include a conventionally known air circulation fan.

[0026] Furthermore, as shown in the illustrated example, it is preferable that the detachable part 21 has a sunlight reflecting layer 21C that reflects ultraviolet rays, visible light, or near-infrared rays. Examples of such a sunlight reflecting layer include a vapor deposition layer or a sheet containing conventionally known aluminum or silver.

[0027] Next, the advantages of the present embodiment will be described. According to the present embodiment, since the roof panel 10 having the above-described radiative cooling layer 11 is provided and the roof trim 20 has a sunshade function in a part thereof and has a detachable part 21 that can be fixed along the inner surface of the window glass 51 of the vehicle 50, there is an advantage that a roof structure can be provided that can further enhance the radiative cooling performance and suppress the temperature rise in the passenger compartment.

[0028] Moreover, according to a preferred form of the present embodiment, since the roof structure 1 further includes an airflow generating device 40 disposed in the space behind the roof trim 20b, the hot air in the passenger compartment can be efficiently supplied to the roof panel, and the cold air after being radiatively cooled by the radiative cooling layer can be efficiently supplied to the passenger compartment, thereby having an advantage that the temperature rise in the passenger compartment can be further suppressed.

[0029] Furthermore, according to a preferred form of the present embodiment, since the detachable part 21 has a sunlight reflecting layer 21C that reflects ultraviolet rays, visible light, or near-infrared rays, when the detachable part is used as an internal sunshade for the window glass (front windshield), the heat input due to solar radiation is suppressed, and there is an advantage that the temperature rise in the passenger compartment can be further suppressed.

[0030] FIG. 3 is a graph showing the cooling effect in the roof structure of the present embodiment. More specifically, in a vehicle without a radiative cooling layer (conventional vehicle) and a vehicle with a radiative cooling layer (radiative cooling vehicle (corresponding to the present embodiment)), the air layer temperature at the head of the driver's seat when the conditions are changed from the state where the detachable part is attached to the state where the detachable part is detached and installed as an internal sunshade on the window glass (front windshield) is measured. As shown in the graph of FIG. 3, the cooling effect can be confirmed in the radiative cooling vehicle.

[0031] Here, the mechanism by which the above-described effects are obtained will be described. Even when the detachment site 21 is attached (see the upper diagram of FIG. 2), it is considered that the radiation cooling layer 11 can cool the gas in the roof trim back space 20b to some extent. However, between the roof trim back space 20b and the passenger compartment 50a, there is the roof trim 20 to which the detachment site 21 is attached, and it is considered that the gas in the passenger compartment 50a is hardly cooled or, if cooled, the cooling is limited.

[0032] On the other hand, in the present invention, in the state where the detachment site 21 is detached (see the lower diagram of FIG. 2), the detachment site 21 is used as an interior sunshade for the window glass (front windshield) 51, and heat input is suppressed by the reflection, absorption, etc. of solar radiation. Not only that, but the opening 20a formed by the detachment of the detachment site 21 allows the roof trim back space 20b and the passenger compartment 50a to communicate, and the cooled gas (cold air) in the roof trim back space 20b descends into the passenger compartment 50a through the opening 20a. Also, the heated gas (hot air) in the passenger compartment 50a rises through the opening 20a. Due to such a gas flow, efficient radiation cooling occurs in the radiation cooling layer, the radiation cooling performance is further enhanced, and it is considered that the temperature rise in the passenger compartment can be suppressed. Also, from such a mechanism, it is preferable that a radiation cooling layer is provided on the roof panel surface portion corresponding to the detachment site when viewed from above the vehicle, but in the present invention, it is not limited thereto (see, for example, paragraph 0028).

[0033] However, as the roof structure of the present invention, it is sufficient to have the above-described configuration (see, for example, paragraph 0007), and needless to say, even if the same effects are obtained by mechanisms other than the above-described mechanism, they are included in the scope of the present invention.

[0034] Also, FIGS. 4 to 7 are diagrams for explaining the roof structures of the second to fifth embodiments. In the following embodiments, the same reference numerals are given to the same constituent parts as those in the above-described first embodiment, and detailed description of the invention is omitted.

[0035] (Second Embodiment) As shown in FIG. 4, the roof structure 2 of this embodiment is different from the roof structure 1 of the first embodiment in that the detachable portion 21 has a folding member 21A that can be folded and stored.

[0036] Here, on the right side in FIG. 4, the folding member 21A is deployed and solar radiation is reflected. On the other hand, on the left side in FIG. 4, the folding member 21A is not deployed and solar radiation is not reflected. For the sake of explanation, the state where the folding member on the left side in FIG. 4 is not deployed is shown, but it goes without saying that this folding member can be deployed. Also, as the folding structure of the folding member, typically, the both ends in the vehicle width direction of the detachable portion as shown in the illustrated example can be folded once toward the center side and stored on the roof panel side in the mounted state, but the present invention is not limited to this. For example, those in which both ends in the vehicle width direction of the detachable portion are bellows-folded and stored on the roof panel side in the mounted state can be cited (not shown).

[0037] Also, as in the illustrated example, it is preferable that the folding member 21A has a vibration control member 21A1. The vibration control member 21A1 is connected to the vibration control member 21A1 provided on the solar light reflection layer 21C. Examples of such a vibration control member 21A1 include members having structures such as a hook-and-loop structure, a hook structure, and a snap button structure.

[0038] Furthermore, as in the illustrated example, the detachable portion 21 may be composed of a plurality of detachable members 21B, and the folding member 21A may be the detachable member 21B.

[0039] Next, the advantages of this embodiment will be described. According to this embodiment, since the detachable part 21 has the above-described folding member 21A, when the detachable part is used as an interior sunshade for the window glass (front windshield), the heat input due to solar radiation is further suppressed by the expansion of the sunshading area. In addition to the advantages of the first embodiment, there is an advantage that the temperature rise in the passenger compartment can be further suppressed.

[0040] Also, according to a preferred form of this embodiment, since the folding member 21A has a vibration restricting member 21A1, the vibration of the folding member during vehicle operation can be restricted. In addition to the advantages of the first embodiment, there is an advantage that the generation of vibration noise of the folding member during vehicle operation can be suppressed.

[0041] Furthermore, according to a preferred form of this embodiment, since the detachable part 21 is composed of a plurality of detachable members 21B, the detachable part can be divided and the detachable members can be installed as interior sunshades on window glasses other than the front windshield, so that the heat input due to solar radiation can be further suppressed. In addition to the advantages of the first embodiment, there is an advantage that the temperature rise in the passenger compartment can be further suppressed.

[0042] (Third Embodiment) The upper view of FIG. 5 is a cross-sectional view showing the mounting state of the detachable part at the A and B parts of the roof structure of this embodiment, and the lower view of FIG. 5 is a cross-sectional view showing the detachment state of the detachable part at the A and B parts of the roof structure of this embodiment. As shown in FIG. 5, the roof structure 3 of this embodiment has a structure similar to the roof structures 1 and 2 of the first or second embodiment, except that the roof trim 20 is arranged to cover the opening 20a formed by detaching the detachable part 21, and further has an intrusion preventing member 22 having a hole 22a capable of ensuring air permeability between the roof trim back space 20b and the passenger compartment 50a.

[0043] Here, the intrusion prevention member 22 preferably has holes that, while ensuring breathability as described above, prevent, for example, the fingers of the occupant from intruding. Examples of such intrusion prevention members include a net-like body or a sheet-like member having such holes.

[0044] Next, the advantages of this embodiment will be described. According to this embodiment, since the roof trim 20 further has the above-described intrusion prevention member 22, for example, it is possible to prevent the fingers of the occupant from intruding into the roof trim back space 20b. In addition to the advantages of the first or second embodiment, there is an advantage that when a wire harness or the like is arranged in a state of being exposed in the roof trim back space, contact with the fingers can be prevented.

[0045] (Fourth Embodiment) The upper view of FIG. 6 is a cross-sectional view showing the mounted state of the detachable parts at the A and B parts of the roof structure of this embodiment, and the lower view of FIG. 6 is a cross-sectional view showing the detached state of the detachable parts at the A and B parts of the roof structure of this embodiment. As shown in FIG. 6, the roof structure 4 of this embodiment has the same structure as the roof structure 3 of the third embodiment, except that the intrusion prevention member 22 is arranged by being slid from the roof trim 20 to the opening 20a.

[0046] Next, the advantages of this embodiment will be described. According to this embodiment, since the intrusion prevention member 22 is arranged by being slid from the roof trim 20 to the opening 20a, it is only necessary to provide a guide such as a rail, for example, to arrange such an intrusion prevention member. In addition to the advantages of the third embodiment, there is an advantage that the intrusion prevention member can be easily arranged.

[0047] (Fifth Embodiment) The upper view of FIG. 7 is a cross-sectional view showing the mounting state of the detachable part at the A and B parts of the roof structure of the present embodiment, and the lower view of FIG. 7 is a cross-sectional view showing the detaching state of the detachable part at the A and B parts of the roof structure of the present embodiment. As shown in FIG. 7, the roof structure 5 of the present embodiment has an intrusion prevention structure in which the roof trim 20 has holes 20c capable of ensuring air permeability between the roof trim back space 20b and the passenger compartment 50a, and has the same structure as the roof structure 4 of the fourth embodiment except that the holes 20c and 22a of each other can be closed when the roof trim 20 and the intrusion prevention member 22 overlap each other.

[0048] Next, the advantages of the present embodiment will be described. According to the present embodiment, since the roof trim 20 has the above-described intrusion prevention structure and the positions of the holes 20c and 22a of each other as viewed from the passenger compartment side can be displaced and closed when the roof trim 20 and the intrusion prevention member 22 overlap each other, when the intrusion prevention member that also functions as a part of the roof trim is slid from the roof trim to the opening and arranged, the above-described gas (hot air or cold air) can flow through the holes of the roof trim, and there is an advantage that the temperature rise in the passenger compartment can be further suppressed compared with the fourth embodiment.

[0049] As described above, the present invention has been described with reference to some embodiments, but the present invention is not limited to these, and various modifications are possible within the scope of the gist of the present invention.

[0050] In the present invention, in order to provide a roof structure that can further enhance the radiative cooling performance and suppress the temperature rise in the passenger compartment, it is essential to include a roof panel 10 having the above-described radiative cooling layer 11, and the roof trim 20 has a detachable part 21 having a sunshade function in a part thereof and can be fixed along the inner surface of the window glass 51 of the vehicle 50.

[0051] Therefore, in the above-described embodiment, the case where the fixing member 30 is provided at the detachable part 21 has been illustrated and described, but the present invention is not limited thereto. In the present invention, for example, a fixing member may be provided on the window glass (front windshield).

[0052] In addition, in the above-described embodiment, the case where the detachable portion 21 has a folding member 21A that can be folded and stored has been described as an example. However, the present invention is not limited to this. In the present invention, for example, the detachable portion 21 may have a slide member that can be slid and stored, or may have both a folding member and a slide member.

[0053] Furthermore, for example, the above-described components are not limited to the components shown in each embodiment. It is possible to change the specifications and details of the roof panel, the radiation cooling layer, the roof trim, the detachable portion, the folding member, the vibration control member, the detachable member, the sunlight reflection layer, the intrusion prevention member, the fixing member, and the air flow generation device, and to delete the suitable components of one embodiment, or to replace or combine the suitable components of one embodiment with the suitable components of other embodiments and apply them.

Explanation of Reference Numerals

[0054] 1, 2, 3, 4, 5 Roof structure 10 Roof panel 11 Radiation cooling layer 20 Roof trim 20a Opening 20b Space behind the roof trim 20c Hole 21 Detachable portion 21A Folding member 21A1 Vibration control member 21B Detachable member 21C Sunlight reflection layer 22 Intrusion prevention member 22a Hole 30 Fixing member 40 Air flow generation device 50 Vehicle 50a Passenger compartment 51 Window glass (front windshield)

Claims

1. A roof structure including a roof panel of a vehicle and a roof trim disposed on the vehicle interior side thereof, wherein the roof panel has a radiation cooling layer disposed on an outer surface thereof and radiating far-infrared rays toward the outside of the vehicle, the roof trim has a detachable portion having a sunshade function in a part thereof, and the detachable portion is fixable along an inner surface of a window glass of the vehicle. A roof structure characterized by the above.

2. The roof structure according to claim 1, wherein the detachable portion has a foldable member that can be folded and housed or a slide member that can be slid and housed.

3. The roof structure according to claim 2, wherein the foldable member or the slide member has a vibration regulating member for regulating vibration.

4. The roof structure according to claim 1, wherein the detachable portion is composed of a plurality of detachable members.

5. The roof structure according to claim 1, wherein the detachable portion has a sunlight reflecting layer that reflects ultraviolet rays, visible light, or near-infrared rays.

6. The roof structure according to claim 1, wherein the roof trim is disposed in an opening formed by detaching the detachable portion, and further has an intrusion preventing member having holes capable of ensuring air permeability between a space behind the roof trim between the roof panel and the roof trim and the passenger compartment.

7. The roof structure according to claim 6, wherein the intrusion preventing member is disposed by sliding from the roof trim into the opening.

8. The roof trim has an intrusion preventing structure having holes capable of ensuring air permeability between the space behind the roof trim and the passenger compartment. When the roof trim and the intrusion prevention member overlap, they can close each other's holes. The roof structure according to claim 7, characterized in that.

9. The roof structure according to claim 1, further comprising an air flow generator disposed in a space behind the roof trim between the roof panel and the roof trim.

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