Coil unit, pavement structure, and construction method for pavement structure

Abstract

To provide a technology that suppresses the rise in coil temperature when power is applied to a power supply coil. [Solution] A coil unit comprising a thin coil and a rod-shaped heat dissipation member for dissipating heat from the thin coil, wherein one end of the rod-shaped heat dissipation member is positioned in contact with the thin coil, and the other end of the rod-shaped heat dissipation member is positioned perpendicular to the coil surface of the thin coil.

Description

[Technical Field]

[0001] The present invention relates to a coil unit, a pavement structure, and a method for constructing a pavement structure. In particular, it relates to a coil unit suitable for contactless power supply to mobile objects such as EVs (electric vehicles), a pavement structure using the coil unit, and a method for constructing the pavement structure. [Background technology]

[0002] In systems that supply power to mobile objects such as EVs in a non-contact manner, the power supply coil is usually installed inside or on the surface of the pavement structure (for example, Patent Documents 1 and 2). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2014-181546 [Patent Document 2] Japanese Patent Publication No. 2015-44422 [Overview of the project] [Problems that the invention aims to solve]

[0004] In the aforementioned pavement structure, if more than 10 kW of power is applied to the coil to obtain a practically necessary charge, heat is generated in the coil, stored in the coil, and the coil temperature rises to about 40°C. In the pavement structure, when the coil temperature rises to about 40°C, the asphalt mixture layer around the coil begins to soften, which can lead to a decrease in load-bearing capacity against traffic loads and become a factor in premature deterioration.

[0005] This invention has been made in view of the above technical background, and aims to provide a technology for suppressing the rise in coil temperature when power is applied to a power supply coil. [Means for solving the problem]

[0006] To achieve the above objective, the present invention provides the following means.

[0007] [1] It includes a thin coil and a rod-shaped heat dissipation member that dissipates the heat generated in the thin coil, One end of the rod-shaped heat dissipation member is positioned to be in contact with the thin coil, A coil unit in which the other end of the rod-shaped heat dissipation member is positioned perpendicular to the coil surface of the thin coil. [2] The coil unit according to [1], wherein the thin coil is an edgewise coil. [3] The coil unit according to [2], wherein one end of the rod-shaped heat dissipation member is positioned at the edgewise bend of the edgewise coil. [4] The coil unit according to [3], having a hole in the edgewise bend portion for inserting the rod-shaped heat dissipation member. [5] The coil unit according to any one of [1] to [4], wherein the rod-shaped heat dissipation member is a pile. [6] The coil unit according to [5], wherein the pile is a spiral pile or screw pile having helical wings. [7] The coil unit according to any one of [1] to [6], wherein the thermal conductivity of the rod-shaped heat dissipation member is 10 to 500 W / (m·K). [8] The volume resistivity of the aforementioned rod-shaped heat dissipation member is 1.0 to 1.0 × 10 23 A coil unit with a resistance of μΩ·cm, as described in one of [1] to [7]. [9] The thin coil of the coil unit described in any one of [1] to [8] is installed in the asphalt mixture layer on the roadbed, A pavement structure in which the other end of the rod-shaped heat dissipation member of the coil unit is positioned in contact with the roadbed.

[10] The paving structure according to [9], wherein the thin coil of the coil unit is embedded in the asphalt mixture layer.

[11] The paving structure according to [9], wherein the thin coil of the coil unit is installed in a recess formed on the surface of the asphalt mixture layer.

[12] A method for constructing the paving structure according to any one of [9] to

[11] , comprising: a step of drilling a hole for inserting the rod-shaped heat dissipation member to a depth reaching from the asphalt mixture layer to the roadbed; a step of installing the coil unit at a position where the rod-shaped heat dissipation member is inserted into the hole; A method for constructing a paving structure, comprising placing a coil unit including a non-contact power supply coil, which has a step of adhering the thin coil of the coil unit and the asphalt mixture layer with an adhesive material, on the asphalt mixture layer on the roadbed, and adhering the coil unit and the asphalt mixture layer with an adhesive material containing resin and sand.

Advantages of the Invention

[0008] According to the coil unit of the present disclosure, since the heat generated when power is applied to the power supply coil is dissipated through the rod-shaped heat dissipation member, it is possible to suppress an increase in the coil temperature due to heat accumulation.

[0009] According to the paving structure of the present disclosure, since the heat generated in the coil when power is applied to the power supply coil is dissipated to the roadbed through the rod-shaped heat dissipation member, it is possible to suppress an increase in the temperature of the asphalt mixture layer around the coil, and it is possible to suppress softening of the asphalt mixture layer caused by an increase in the temperature of the asphalt mixture layer.

Brief Description of the Drawings

[0010] [Figure 1] It is an explanatory view of a coil unit in an embodiment of the present invention. [Figure 2] It is an explanatory view of a paving structure in an embodiment of the present invention. [Figure 3]This is a graph showing the measurement results of Example 1, illustrating the time applied to the coil unit and the temperature changes of each part of the edgewise coil. [Modes for carrying out the invention]

[0011] One embodiment of the present invention will be described in detail below.

[0012] <Coil Unit> As shown in Figure 1, the coil unit in one embodiment includes a thin coil 1 and a rod-shaped heat dissipation member 2 that dissipates heat generated in the thin coil 1. One end of the rod-shaped heat dissipation member 2 is positioned in contact with the thin coil 1, and the other end of the rod-shaped heat dissipation member 2 is positioned perpendicular to the coil surface of the thin coil 1. In this disclosure, "perpendicular" means that the angle with the perpendicular to the coil surface is 0 to 10°. The angle is preferably 0 to 5°, and more preferably 0°.

[0013] (Thin coil) The thin coil may be an edgewise coil formed into a predetermined shape by edgewise winding from a conductive rectangular cross-section plate material. The edgewise coil may be a planar coil formed by spirally winding the plate material in the same plane, and may have multiple edgewise bends within the same plane.

[0014] The thermal conductivity of the aforementioned plate material may be 200-450 W / (m·K), 230-430 W / (m·K), or 235-425 W / (m·K). The thermal conductivity may also be determined from the thermal diffusivity using the following formula (1). The thermal diffusivity in the following formula (1) can be measured, for example, using a Xenon Flash Laser Analyzer LFA467 HyperFlash manufactured by Netch Japan Co., Ltd. Thermal conductivity (W / (m·K)) = Specific gravity (g / cm³) 3 ) × Specific heat (J / g·K) × Thermal diffusivity (mm 2 / s)…Formula (1)

[0015] The volume resistivity of the aforementioned plate material may be 0.5 to 10.0 μΩ·cm, 1.0 to 5.0 μΩ·cm, or 1.5 to 3.0 μΩ·cm. The volume resistivity can be calculated by measuring the resistance value using a low-resistivity resistivity meter and using the resistivity correction coefficient and the thickness of the resin molded body. For example, it can be measured at room temperature in air using a four-probe resistivity measuring device (Loresta AX MCP-T370, manufactured by Mitsubishi Chemical Analytec Co., Ltd.).

[0016] The aforementioned plate material may be any one selected from the group consisting of copper, aluminum, silver, and alloys thereof.

[0017] The edgewise coil may have holes 4 in the edgewise bend 3 for inserting a rod-shaped heat dissipation member 2. As shown in Figure 1, the planar coil may have holes 4 at four locations in the outermost edgewise bend 3 and at four locations in the innermost edgewise bend 3. In this disclosure, the edgewise bend 3 refers to the corner portion of the edgewise coil. By forming holes 4 in the edgewise bend 3, the current-carrying area of ​​the edgewise coil can be widened, and the reduction in inductance due to the formation of holes 4 can be avoided.

[0018] (Rod-shaped heat dissipation member) The rod-shaped heat dissipation member 2 may be a pile that has the function of dissipating heat generated in the thin coil 1, as well as the function of suppressing horizontal displacement of the thin coil 1 installed in the asphalt mixture layer due to traffic loads. The shape of the pile is not limited and may be a spiral pile with spiral-shaped wings or a screw pile.

[0019] From the viewpoint of improving heat dissipation, the rod-shaped heat dissipation member 2 is preferably a good conductor of heat, and from the viewpoint of suppressing the electrical influence on the thin coil 1 when it is energized, it is preferably a poor conductor of electricity.

[0020] The thermal conductivity of the rod-shaped heat dissipation member 2 may be 10 to 500 W / (m·K), may be 20 to 420 W / (m·K), may be 20 to 300 W / (m·K), or may be 20 to 150 W / (m·K). The thermal conductivity may be the thermal conductivity in the direction perpendicular to the coil surface. The thermal conductivity may be obtained from the thermal diffusivity by the following formula (1). The thermal diffusivity in the following formula (1) can be measured, for example, using a xenon flash laser analyzer "LFA467 HyperFlash" manufactured by Netzsch Japan Co., Ltd. Thermal conductivity (W / (m·K)) = Specific gravity (g / cm 3 ) × Specific heat (J / g·K) × Thermal diffusivity (mm 2 / s) … Formula (1)

[0021] The volume resistivity of the rod-shaped heat dissipation member 2 may be 1.0 μΩ·cm to 1.0×10 23 μΩ·cm, may be 1.6 μΩ·cm to 1.0×10 22 μΩ·cm, may be 2.8 μΩ·cm to 1.0×10 21 μΩ·cm, or may be 50 μΩ·cm to 1.0×10 20 μΩ·cm. The volume resistivity can be calculated from the measured resistance value using a low-resistance resistivity meter and the thickness of the resin molded body and the resistivity correction coefficient. For example, it can be measured at room temperature in the atmosphere using a four-probe resistivity measurement device (Loresta AX MCP-T370, manufactured by Mitsubishi Chemical Analytech Co., Ltd.).

[0022] The rod-shaped heat dissipation member may be any one selected from the group consisting of copper, aluminum, silver, stainless steel, iron, aluminum nitride, silicon nitride, and their alloys.

[0023] <Pavement structure> The cross-section of a road consists of layers called "surface layer (asphalt mixture layer 6) ~ intermediate layer (asphalt mixture layer 6) ~ base layer (asphalt mixture layer 6) ~ upper subbase (subbase 5) ~ lower subbase (subbase 5) ~ subgrade ~ road body," in order from the surface to the depths, and the portion of these layers combined, consisting of the asphalt mixture layer 6 and the subbase 5, is defined as the pavement. In one embodiment, as shown in Figure 2, the pavement structure of this disclosure is made by installing a thin coil 1 of a coil unit on the asphalt mixture layer 6 above the subbase, and arranging the other end of the rod-shaped heat dissipation member 2 of the coil unit so as to be in contact with the subbase 5. Here, "the other end of the rod-shaped heat dissipation member is in contact with the subbase" means both a form in which the tip of the rod-shaped heat dissipation member is in contact with the subbase, and a form in which the rod-shaped heat dissipation member is driven into the subbase and the tip of the rod-shaped heat dissipation member is located inside the subbase.

[0024] Asphalt used in asphalt mixtures for paving is a "thermoplastic" material, meaning it softens and deforms at high temperatures. The temperature at which asphalt begins to soften from a solid to a liquid state is defined as the "softening point," and the softening point of commonly used asphalt is standardized to around 40-50°C. As described above, in conventional non-contact power supply systems, applying more than 10kW of power to the power supply coil to obtain a practically necessary charge causes the coil temperature to rise to about 40°C, which leads to the softening of the asphalt mixture around the coil. However, in the pavement structure of this disclosure, the heat generated by supplying power to the coil can be quickly dissipated to the roadbed via a rod-shaped heat dissipation member. This suppresses the accumulation of heat in the coil and the resulting temperature rise of the coil, thus avoiding the softening of the asphalt mixture around the coil.

[0025] The method of embedding the coil unit is not limited. For example, when embedding the coil unit during the construction of a new pavement, the thin coil may be embedded in a trough within the pavement. When embedding the coil unit in an existing pavement, the thin coil may be installed in a recess formed by cutting the pavement surface.

[0026] The coil unit may be bonded to the burial site using an adhesive material containing resin and sand. By bonding with an adhesive material containing resin and sand, structural strength can be ensured so that the power supply coil does not compress or deform under the running load from a moving vehicle, even when the coil unit is buried in an asphalt mixture layer. The adhesive material may be an adhesive material made by mixing one or more resins selected from the group consisting of epoxy resins, acrylic resins, and urethane resins with fine aggregate with a maximum particle size of 2 mm or less.

[0027] <Construction methods for pavement structures> In one embodiment, the construction method for the pavement structure may include the steps of: drilling a hole for inserting the rod-shaped heat dissipation member to a depth that reaches from the asphalt mixture layer to the roadbed; installing the coil unit in a position where the rod-shaped heat dissipation member is inserted into the hole; and bonding the thin coil of the coil unit to the asphalt mixture layer with an adhesive material. [Examples]

[0028] Next, specific embodiments of the present invention will be described, but the present invention is not particularly limited to those embodiments.

[0029] <Example 1: Coil Unit> Copper plate (C1100, volume resistivity 1673 μΩ·cm, thermal conductivity 371 W / (m·K), average specific heat 380 J / (kg·K), density 8.93 g / cm³) 3 An edgewise coil (size 600 x 800 mm, number of turns 8, pitch 28, wire diameter 13 mm, thickness 2.0 mm) was created by shaping the wire into the form shown in Figure 1 using edgewise winding. Holes for inserting rod-shaped heat dissipation members were formed at four locations in the outermost edgewise bend and at four locations in the edgewise bend adjacent to the innermost circumference, and screw piles (SUS410, volume resistivity 57 μΩ·cm, thermal conductivity 24 W / (m·K), average specific heat 460 J / (kg·K), density 7.75 g / cm³) were inserted into the holes. 3A wire with an outer diameter of φ10mm, a total length of 70mm, and a thread length of 60mm was inserted. Copper tape was wrapped around the contact area between the edgewise coil and the pile to fill the gap, and a coil unit was obtained.

[0030] The rod-shaped heat dissipation member of the coil unit was pointed towards the ceiling, and the edgewise coil portion of the coil unit was placed on a measurement table. After determining the DC resistance by passing a current (5-50A) through the coil unit on the measurement table, a DC current that consumes 120W was derived. The derived current was applied as a constant current to the coil unit on the measurement table, and the temperature of the coil was measured. The measurement results are shown in Figure 3 and Table 1. In Tables 1-3 below, the coil outer angle refers to the edgewise bend at the outermost circumference of the coil, the coil inner angle refers to the edgewise bend on the inner circumference side of the coil (the innermost circumference or the circumference adjacent to the innermost circumference), and the coil middle angle refers to the edgewise bend located between the coil outer angle and the coil inner angle.

[0031] [Table 1]

[0032] <Comparative Example 1: Edgewise coil (with holes)> Copper plate (C1100, volume resistivity 1673 μΩ·cm, thermal conductivity 371 W / (m·K), average specific heat 380 J / (kg·K), density 8.93 g / cm³) 3 An edgewise coil (size 600 x 800 mm, number of turns 8, pitch 28, wire diameter 13 mm, thickness 2.0 mm) was created by shaping the material into the form shown in Figure 1 using edgewise winding. Similar to Example 1, holes were formed at eight locations in the edgewise bend of the edgewise coil. An edgewise coil (with holes) was placed on a measurement table, and the DC resistance was determined by applying a current (5-50A). Then, a DC current that consumed 120W was derived. This derived current was applied as a constant current to the edgewise coil (with holes) on the measurement table, and the temperature and coil resistance were measured. The measurement results are shown in Table 2.

[0033] [Table 2]

[0034] <Comparative Example 2: Edgewise coil (without holes)> Copper plate (C1100, volume resistivity 1673 μΩ·cm, thermal conductivity 371 W / (m·K), average specific heat 380 J / (kg·K), density 8.93 g / cm³) 3 An edgewise coil (size 600 x 800 mm, 8 turns, 28 pitch, wire diameter 13 mm, thickness 2.0 mm) was created by shaping the material into the form shown in Figure 1 using edgewise winding. A measuring table was used to place an edgewise coil (without holes), and after determining the DC resistance by applying a current (5-50A), a DC current that would consume 120W was derived. The derived current was applied as a constant current to the edgewise coil (without holes) placed on the measuring table, and the temperature and resistance of the coil were measured. The measurement results are shown in Table 3.

[0035] [Table 3]

[0036] As shown in Tables 1 to 3, it was confirmed that the temperature rises most rapidly in the straight section of the coil when heat is applied. As shown in Tables 2 and 3, in edgewise coils where heat is not dissipated by a rod-shaped heat dissipation member, it was confirmed that the temperature rises most rapidly in the inner edgewise bend of the edgewise bend when heat is applied. As shown in Table 1 and Figure 3, it was confirmed that the coil unit of the present invention suppresses the temperature rise in the edgewise bend (inner and outer corners of the coil) where the pile is inserted. [Explanation of symbols]

[0037] 1 Thin coil 2. Rod-shaped heat dissipation member 3. Edgewise bend section 4 Hole 5-way track 6. Asphalt mixture layer

Claims

1. It includes a thin coil and a rod-shaped heat dissipation member that dissipates heat from the thin coil, One end of the rod-shaped heat dissipation member is positioned to be in contact with the thin coil, A coil unit in which the other end of the rod-shaped heat dissipation member is positioned perpendicular to the coil surface of the thin coil.

2. The coil unit according to claim 1, wherein the thin coil is an edgewise coil.

3. The coil unit according to claim 2, wherein one end of the rod-shaped heat dissipation member is positioned at the edgewise bend of the edgewise coil.

4. The coil unit according to claim 3, wherein the edgewise bend portion has a hole for inserting the rod-shaped heat dissipation member.

5. The coil unit according to claim 1, wherein the rod-shaped heat dissipation member is a pile.

6. The coil unit according to claim 5, wherein the pile is a spiral pile or screw pile equipped with spiral wings.

7. The coil unit according to claim 1, wherein the thermal conductivity of the rod-shaped heat dissipation member is 10 to 500 W / (m·K).

8. The volume resistivity of the rod-shaped heat dissipation member is 1.0 to 1.0 × 10 ２３ The coil unit according to claim 1, wherein the resistance is μΩ·cm.

9. The thin coil of the coil unit according to any one of claims 1 to 8 is installed in the asphalt mixture layer on the roadbed, A pavement structure in which the other end of the rod-shaped heat dissipation member of the coil unit is positioned in contact with the roadbed.

10. The pavement structure according to claim 9, wherein the thin coil of the coil unit is embedded in the asphalt mixture layer.

11. The pavement structure according to claim 9, wherein the thin coil of the coil unit is installed in a recess formed on the surface of the asphalt mixture layer.

12. A method for constructing a pavement structure according to claim 9, The process involves drilling a hole for inserting the rod-shaped heat dissipation member to a depth that reaches from the asphalt mixture layer to the roadbed, The steps include: installing the coil unit in a position where the rod-shaped heat dissipation member is inserted into the hole; A method for constructing a pavement structure, comprising the step of bonding the thin coil of the coil unit and the asphalt mixture layer with an adhesive material.

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