Coil and power transfer device

Abstract

To provide a coil and a power transfer device.SOLUTION: A coil includes a shield consisting of a first portion of a sheet-shaped magnetic material and a second portion of a coaxial ring-shaped magnetic material of a different diameter erected in the center of the first portion, and a coil conductor housed between the coaxial ring-shaped second portion of the shield.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a coil used for wireless power supply to a battery mounted on an electric moving body and a power transmission and reception device using the coil.

Background Art

[0002] Towards the realization of a decarbonized society, electric moving bodies that drive a driving motor with electric power stored in a driving battery have begun to spread. Electric moving bodies include not only electric vehicles but also flying bodies such as automated guided vehicles, forklifts, so-called drones, and water mobilities such as electric propulsion ships. As a method for supplying power to the driving battery mounted on these electric moving bodies, a wireless power supply system that supplies power wirelessly instead of via a power cable has been put into practical use.

[0003] In a wired power supply system, there is an advantage that high-speed power supply is possible. On the other hand, in wireless power supply, there is an advantage that power supply can be started without the user's operation as long as the electric moving body can be parked stationary according to the location of the fixed power supply coil.

[0004] In wireless power supply, in order to reduce the leakage of magnetic flux in the power supply coil and the power receiving coil, particularly in the power receiving coil, a sheet-shaped magnetic shield is provided on the surface opposite to the facing surface side (Patent Document 1, etc.). By providing a magnetic shield, it is expected to converge magnetic field lines and improve power transmission efficiency.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] In wireless power supply for an electric moving body, even if the opposing positions of the power supply coil and the power receiving coil are displaced, it is desirable to maintain the resonance height and coupling degree of the resonance coil as large as possible and maintain the power transmission efficiency.

[0007] An object of the present invention is to provide a coil and a power transmission / reception device that are resistant to positional displacement and can maintain power transmission efficiency.

Means for Solving the Problems

[0008] The coil according to an embodiment of the present disclosure includes a shield composed of a first portion of a sheet-shaped magnetic body and a second portion composed of coaxial annular magnetic bodies having different diameters erected at the center of the first portion, and a coil conductor housed between the coaxial annular second portions of the shield.

Effects of the Invention

[0009] According to the coil and the power transmission / reception device of the present disclosure, the shield can maintain high power transmission efficiency and be resistant to positional displacement.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Modes for Carrying Out the Invention

[0011] The present disclosure will be specifically described with reference to the drawings showing embodiments thereof.

[0012] (First Embodiment) FIG. 1 is a schematic diagram of a power transmission and reception device 100 according to the first embodiment. The power transmission and reception device 100 includes a power supply device 1 installed on a road surface and a power reception device 2 provided on an electric moving body V.

[0013] The power supply device 1 includes a power supply coil 11, a casing 12 for positioning the power supply coil 11, and a power source 13 for providing a current to the power supply coil 11. The power supply device 1 is provided at the back or side of the parking area of the electric moving body V. The casing 12 is made of, for example, aluminum, has a flat substantially rectangular parallelepiped shape, and houses the power supply coil 11 so that the direction perpendicular to the wide surface is the axis. The casing 12 is installed on the road surface so that the wide surface is parallel to the road surface. The power supply coil 11 and the casing 12 may be embedded under the road surface.

[0014] The power reception device 2 includes a power reception coil 21, a casing 22 for positioning the power reception coil 21, and a transmission unit 23 for transmitting the power received by the power reception coil 21. The casing 22 of the power reception device 2 is made of, for example, aluminum, has a flat substantially rectangular parallelepiped shape, and houses the power reception coil 21 at the bottom of the electric moving body V so that the axis is in the vertical direction.

[0015] The driver of the electric moving body V moves the electric moving body V to a parking area and parks it. At this time, the power supply coil 11 and the power receiving coil 21 are parked so as to be coaxial as much as possible. A guide may be provided to guide the power supply coil 11 and the power receiving coil 21 so as to face each other. The power supply device 1 of the power transmission device 100 automatically or by the operation of the driver detects that the electric moving body V equipped with the power receiving device 2 has been parked. When the power supply device 1 detects that the electric moving body V has been parked, it automatically or by the operation of the driver or an operator in the parking area supplies power to the power receiving device 2. The power received by the power receiving device 2 is supplied to the battery 3 for driving the electric moving body V via the transmission unit 23, and wireless power transmission and reception are realized.

[0016] As described above, even if the power supply coil 11 and the power receiving coil 21 are guided by a guide so as to be coaxial as much as possible, due to the accuracy of the driving operation of the electric moving body V, it is very difficult to make the misalignment of the axes between the power supply coil 11 and the power receiving coil 21 zero. Also, depending on the vehicle type, the height at which the power receiving coil 21 is provided varies within a specified range, and the size of the power receiving coil 21 varies with respect to the power supply coil 11 within a specified range.

[0017] The power supply device 1 of the power transmission device 100 according to the present disclosure can maintain high power transmission efficiency and be resistant to positional misalignment by enhancing the function of the shield by the shape of the shield 121 provided on the casing 12 and reducing the spatial magnetic path length with respect to the diversity of positional misalignment and distance. Similarly, the power receiving device 2 can maintain high power transmission efficiency and be resistant to positional misalignment by enhancing the function of the shield by the shape of the shield 221 provided on the casing 22 and reducing the spatial magnetic path length. Hereinafter, the shape of the shields 121 and 221 will be described in detail.

[0018] FIG. 2 is a schematic perspective view of the power supply coil 11, the casing 12, and the shield 121. The casing 12 includes a frame 122 assembled into a substantially flat rectangular parallelepiped, a shield 121 fixed to the frame 122 via a support 124, and a housing 123 that covers the whole.

[0019] The frame 122 and the housing 123 are made of a non-magnetic material such as aluminum. The frame 122 has a support 124 that supports the shield 121. The support 124 is, for example, a flat plate made of the same material as the frame 122 and is provided so as to partition the space defined by the frame 122 in the thickness direction. The support 124 is not limited to being flat and may be lattice-shaped.

[0020] The shield 121 is made of a magnetic material such as ferrite or a soft magnetic metal material. The shield 121 is composed of a sheet-like first portion 1211 fixed to the support 124 and a second portion 1212 erected coaxially in a ring shape with different diameters at the center of the first portion 1211. The shield 121 may be composed of an integral ferrite core formed by the first portion 1211 and the second portion 1212, or may be formed by bonding a card-shaped ferrite core so as to form the first portion 1211 and the second portion 1212. The coil conductor of the power supply coil 11 is fixed inside the annular second portion 1212 of the shield 121.

[0021] The sheet-like first portion 1211 of the shield 121 is substantially rectangular in shape, similar to the broad surface of the casing 12. The first portion 1211 may be circular in shape with substantially the same diameter as the outer diameter of the second portion 1212 (see FIG. 4), or may be annular with a space provided in the central portion. The sheet-like first portion 1211 and the second portion 1212 may be configured such that the cross-sectional U-shape (channel shape) is continuous in an annular shape. The sheet-like first portion 1211 of the shield 121 is fixed to the support 124 fixed to the frame 122 substantially parallel to the broad surface of the casing 12. The first portion 1211 functions to return the electromagnetic field generated by the power supply coil 11 to the power supply coil 11. As a result, it is possible to converge the magnetic field lines generated by the current in the power supply coil 11 in the space on the side opposite to the first portion 1211 with the power supply coil 11 interposed therebetween.

[0022] The height (thickness) of the double-ring-shaped second portion 1212 of the shield 121 is the same as the height (thickness) of the power supply coil 11. The height (thickness) of the second portion 1212 may be higher than the height (thickness) of the power supply coil 11.

[0023] Since the power receiving coil 21 and the shield 221 also have the same shape as the power supply coil 11 and the shield 121 shown in FIG. 2, illustration and detailed description are omitted. The sheet-like first portion 2211 of the shield 221 of the power receiving coil 21 is rectangular or circular so that the magnetic field does not enter the vehicle body.

[0024] FIG. 3 is an explanatory view of the shields 121 and 221. FIG. 3 shows a schematic cross-sectional view of the shields 121 and 221 when the power supply coil 11 and the power receiving coil 21 are arranged opposite to each other. For the shield 121, a cross-section at A-A in FIG. 2 is shown. FIG. 3A shows a state where the opposing distance is relatively short, and FIG. 3B shows a state where the opposing distance is farther than the arrangement shown in FIG. 3A.

[0025] In the shields 121 and 221, as shown in FIGS. 2 and 3, the annular second portions 1212 and 2212 protrude from the sheet-like first portions 1211 and 2211 with respect to each other. The magnetic flux generated in the poloidal direction with respect to the power supply coil 11 is more likely to be absorbed into the annular second portion 1212 than in the air. As a result, the outside of the annular second portion 1212 becomes a wall, preventing the electromagnetic field generated by the power supply coil 11 from leaking to the outside in the radial direction of the coil and strengthening the focusing. The magnetic flux generated from the power supply coil 11 is induced from the annular second portion 1212 to the annular second portion 2212 of the opposing power receiving coil 21.

[0026] As shown in FIG. 3A, the spatial magnetic path length decreases compared to the case where the shields 121 and 221 are composed of only the sheet-like first portions 1211 and 2211. Therefore, as shown in FIG. 3B, even if the distance between the power supply coil 11 and the power receiving coil 21 is increased compared to the case where a shield composed of only the sheet-like first portions 1211 and 2211 is used, the spatial magnetic path length can be decreased. Even if the opposing distance is increased, since the second portions 1212 and 2212 composed of ferrite cores protrude toward the opposing surface side compared to the case where a shield composed of only the sheet-like first portions 1211 and 2211 is used, the spatial magnetic path length can be decreased and a decrease in the coupling degree can be suppressed.

[0027] In this way, due to the shape of the shields 121 and 221, it is possible to enhance the shield function, decrease the spatial magnetic path length, suppress a decrease in the coupling degree, and realize the power supply coil 11 and the power receiving coil 21 that can maintain a high power transmission efficiency.

[0028] FIG. 4 is a cross-sectional view showing another aspect of the shields 121 and 221 of the first embodiment. The shields 121 and 221 shown in FIG. 4 are different from the shields 121 and 221 shown in FIGS. 2 and 3 in terms of...

[0029] (Second Embodiment) In the second embodiment, the shapes of the shields 121 and 221 are different from those of the first embodiment. The configuration of the power transmission and reception device 100 of the second embodiment other than the shields 121 and 221 is the same as the configuration of the power transmission and reception device 100 of the first embodiment. Therefore, the same reference numerals are given to the common components and the detailed description thereof is omitted.

[0030] FIG. 5 is a schematic perspective view of the power supply coil 11, the casing 12, and the shield 121 of the second embodiment. The casing 12 includes a frame 122 assembled into a substantially flat rectangular parallelepiped, a shield 121 fixed to the frame 122 via a support 124, and a housing 123 that covers the whole. Since the frame 122, the housing 123, and the support 124 are the same as those of the first embodiment, the detailed description thereof is omitted.

[0031] The shield 121 of the second embodiment is made of a magnetic material such as ferrite or a soft magnetic metal material, similar to the first embodiment. The shield 121 is composed of a sheet-like first portion 1211, a second portion 1212 erected coaxially in a ring shape with different diameters in the center of the first portion 1211, and a flange portion 1213 where the ends of the first portion 1211 project inward and outward in the radial direction. The shield 121 may be composed of an integral ferrite core, or may be composed by bonding card-shaped ferrite cores. The coil conductor of the power supply coil 11 is fixed between the annular second portions 1212 of the shield 121.

[0032] Also in the second embodiment, the sheet-like first portion 1211 of the shield 121 is substantially the same size as the broad surface of the casing 12. The first portion 1211 may be circular with a diameter substantially the same as the outer diameter of the second portion 1212 (see FIG. 7), or may be annular with a space provided in the central portion. The sheet-like first portion 1211 and the second portion 1212 may be configured to form a shape in which a U-shaped (C-shaped) cross-section is continuous in an annular shape. The sheet-like first portion 1211 of the shield 121 functions to return the electromagnetic field generated by the power supply coil 11 to the power supply coil 11. Thereby, it is possible to converge the magnetic lines of force generated by the current in the power supply coil 11 in the space on the side opposite to the sheet-like first portion 1211 with the power supply coil 11 interposed therebetween.

[0033] The height (thickness) of the double-ring-shaped second portion 1212 of the shield 121 is the same as the height (thickness) of the power supply coil 11. The height (thickness) of the second portion 1212 may be higher than the height (thickness) of the power supply coil 11.

[0034] Since the power receiving coil 21 and the shield 221 also have the same shape as the power supply coil 11 and the shield 121 shown in FIG. 5, illustration and detailed description are omitted. The sheet-like first portion 2211 of the shield 221 for the power receiving coil 21 is rectangular or circular so that the magnetic field does not enter the interior of the vehicle body.

[0035] FIG. 6 is an explanatory view of the shields 121 and 221 of the second embodiment. FIG. 6 shows a schematic cross-sectional view of the shields 121 and 221 when the power supply coil 11 and the power reception coil 21 are arranged to face each other. For the shield 121, a cross-section taken along line B-B in FIG. 5 is shown. FIG. 6A shows a state in which the power supply coil 11 and the power reception coil 21 are facing each other substantially coaxially, and FIG. 6B shows a state in which a positional deviation has occurred on the facing surface.

[0036] As shown in FIGS. 5 and 6, the shields 121 and 221 have annular second portions 1212 and 2212 protruding from sheet-like first portions 1211 and 2211, respectively. The magnetic flux generated in the poloidal direction with respect to the power supply coil 11 is more likely to be absorbed into the annular second portion 1212 than into the air. As a result, the outside of the annular second portion 1212 serves as a wall, preventing the electromagnetic field generated by the power supply coil 11 from leaking to the outside in the radial direction of the coil and enhancing the focusing. The magnetic flux generated from the power supply coil 11 is absorbed into the annular second portion 1212 and the flange portion 1213. The magnetic flux absorbed into the second portion 1212 and the flange portion 1213 is induced in the portion of the annular second portion 2212 and the flange portion 2213 of the opposing power reception coil 21 that faces the shortest distance.

[0037] Even if there is a positional deviation on the facing surface, as shown in FIG. 6B, it travels along the shortest distance. Therefore, if the facing distance does not change, there is almost no change in the spatial magnetic path length, and the coupling degree of the resonant coils does not decrease. Due to the presence of the flange portions 1213 and 2213, even when compared with the shields 121 and 221 of the first embodiment, there is no change in the spatial magnetic path length with respect to the positional deviation, and the coupling degree of the resonant coils can be maintained. When compared with the case of using a shield composed only of the sheet-like first portions 1211 and 2211, furthermore, even if the distance between the power supply coil 11 and the power reception coil 21 is increased, the magnetic path length can be decreased.

[0038] The space inside the second portions 1212 and 2212 of the shields 121 and 221 of the second embodiment may also be filled with a ferrite core.

[0039] In this way, due to the shapes of the shields 121 and 221, the shielding function can be enhanced, and the spatial magnetic path length can be reduced, so that a power feeding coil 11 and a power receiving coil 21 that are resistant to positional deviation and can maintain a high power transmission efficiency by suppressing a decrease in coupling can be realized.

[0040] FIG. 7 is a cross-sectional view showing another aspect of the shields 121 and 221 of the second embodiment. The shields 121 and 221 shown in FIG. 7 do not have the sheet-like first portions 1211 and 2211 protruding outward in the radial direction of the coil as compared with the shields 121 and 221 shown in FIGS. 5 and 6. That is, the sheet-like first portions 1211 and 2211 are each circular sheet-like. By adopting such a configuration, it is possible to reduce the leakage of magnetic flux to the outside in the radial direction and strengthen the focusing of magnetic flux.

[0041] FIG. 8 is a cross-sectional view showing another aspect of the shield 121 of the second embodiment. In the shield 121 of the power feeding coil 11 shown in FIG. 8, the inside of the second portion 1212 is further filled with a magnetic material 1214 such as ferrite. By adopting such a configuration, it is possible to strengthen the focusing of magnetic flux. The demerit that the weight of the power feeding coil 11 side increases due to the increase of the ferrite core is less than that of the electric moving body V.

[0042] In the above-described first and second embodiments, the electric moving body V has been described as a four-wheel electric vehicle, but it is not limited thereto. The electric moving body V may be an unmanned carrier vehicle, a motorcycle, a forklift, a flying body such as a so-called drone, or a water moving body such as an electric propulsion ship. The installation mode of the casing 12 of the power feeding device 1 is changed according to the type of the electric moving body V. In the case of an unmanned carrier vehicle, a forklift, or a water moving body, since the power receiving coil 21 may be provided with its axis substantially parallel to the horizontal direction on the side surface or the back surface of the moving body, the casing 12 is erected on the road surface so that the power feeding coil 11 faces the power receiving coil 21. When the electric moving body V is a flying body, it may be placed on the road surface with its axis substantially parallel to the vertical direction without being buried in the road surface.

[0043] The power supply coil 11 and the power receiving coil 21 are not limited to coils wound in a circular shape. They may be square, or may be polygons such as pentagons or hexagons. Therefore, the second part is not limited to an annular shape, and may be a polygon such as a square, and does not have to be a regular polygon.

[0044] The embodiments disclosed as above are illustrative in all respects and not restrictive. The scope of the present invention is indicated by the claims, and includes all modifications within the meaning and scope equivalent to the claims.

Explanation of Reference Numerals

[0045] 1 Power supply device 11 Power supply coil 12 Casing 121 Shield 1211 First part 1212 Second part 1213 Flange portion 21 Power receiving coil 22 Casing 221 Shield 2211 First part 2212 Second part 2213 Flange portion

Claims

1. A shield composed of a first portion of a sheet-like magnetic body and a second portion composed of coaxial annular magnetic bodies of different diameters erected at the center of the first portion, A coil conductor housed between the coaxial annular second portions of the shield A coil comprising the above.

2. The height of the second portion is equal to or greater than the height of the coil conductor The coil according to Claim 1.

3. The coil according to Claim 1 or 2, wherein the first portion has substantially the same shape as the outer edge of the second portion.

4. The coil according to Claim 1 or 2, wherein the shield has flange portions projecting radially inward and outward from the ends of the second portion.

5. The coil according to Claim 1 or 2, wherein the inside of the second portion of the shield is filled with a magnetic body.

6. Comprising the coil according to Claim 1 or 2, A power transmission and reception device that wirelessly transmits and receives power with the coil.

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