JP2014193056A - Wireless power transmission device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wireless power transmission device capable of reducing unwanted radiation noise even when a change of distance or a positional deviation between a power transmitting coil and a power receiving coil occurs.SOLUTION: A wireless power transmission device S1 comprises: a power transmitting coil L1; a power transmitting side shield part 11 disposed on a side of the power transmitting coil L1 opposite to the surface facing a power receiving coil L2; the power receiving coil L2; and a power receiving side shield part 21 disposed on a side of the power receiving coil L2 opposite to the surface facing a power transmitting coil L1. An outer circumferential length of the transmitting side shield part 11 is smaller than an outer circumferential length of the receiving side shield part 21. When viewed from the opposing direction of the transmitting side shield part 11 and the receiving side shield part 21 while the transmitting side shield part 11 and the receiving side shield part 21 are located in such a way that their center points face each other, all of the outer contours of the transmitting side shield part 11 are located inward from all of the outer contours of the receiving side shield part 21.

Description

  The present invention relates to a wireless power transmission device.

  Wireless power transmission technology that supplies power wirelessly without using a power cord or cable is drawing attention. Wireless power transmission technologies include (A) a type that uses electromagnetic induction (for short distances), (B) a type that uses radio waves (for long distances), and (C) a type that uses magnetic field resonance (medium distances). Can be roughly divided into three types.

  Type (C), which utilizes the magnetic field resonance phenomenon, is a relatively new technology, and can achieve high power transmission efficiency even in the middle range of several meters. For example, a receiving coil is installed at the bottom of an electric vehicle. A proposal to send power wirelessly from a power supply coil arranged underground or on the ground is also being studied.

  By the way, when wireless high-power transmission is performed, there is a problem in that unnecessary radiation noise of electromagnetic waves is generated in a space outside the power transmission device and adversely affects peripheral electronic devices.

  In order to solve the above-described problem, Patent Document 1 proposes a non-contact power feeding device including a coil, a magnetic core, and a base plate on the primary side and the secondary side in order from the air gap side. In this non-contact power feeding device, the base plate shields external leakage of leakage magnetic flux by eddy current induced internally.

JP 2010-93180 A

  However, the non-contact power feeding device disclosed in Patent Document 1 is not mentioned regarding the dimensions of the primary and secondary magnetic cores and the base plate, and the distance change and position between the power transmission coil and the power reception coil are not mentioned. When deviation occurs, the leakage magnetic flux increases, and unnecessary radiation noise may increase.

  The present invention has been made in view of the above problem, and can wirelessly reduce unnecessary radiation noise even when the distance between the power transmitting coil and the power receiving coil is changed or the positional deviation occurs. An object is to provide a power transmission device.

  A wireless power transmission device according to the present invention is a device in which electric power is transmitted wirelessly when a power transmission coil and a power reception coil face each other, and is opposite to a surface facing the power reception coil and the power reception coil of the power transmission coil. A power transmission side shield portion disposed on the side, a power reception coil, and a power reception side shield portion disposed on the opposite side of the surface of the power reception coil facing the power transmission coil, and the outer peripheral length of the power transmission side shield portion is In the state where the outer peripheral length of the power receiving side shield part is smaller and the center point of the power transmitting side shield part and the center point of the power receiving side shield part are opposed to each other, it is viewed from the facing direction of the power transmitting coil and the power receiving coil. Thus, all the outer contours of the power transmission side shield part are located inside of all the outer contours of the power reception side shield part.

  According to the present invention, the outer peripheral length of the power transmission side shield part is smaller than the outer peripheral length of the power reception side shield part, and the center point of the power transmission side shield part and the center point of the power reception side shield part are opposed to each other. In this state, when viewed from the opposing direction of the power transmission coil and the power receiving coil, all outer contours of the power transmission side shield portion are located outside of all outer contours of the power reception side shield portion. Therefore, unnecessary radiation noise can be reduced even when the distance between the power transmitting coil and the power receiving coil is changed or the position is shifted.

  Preferably, the outer peripheral length of the power transmission coil is smaller than the outer peripheral length of the power reception coil, and the power transmission coil and the power reception coil are positioned in a state where the center point of the power transmission coil and the center point of the power reception coil are opposed to each other. When viewed from the opposite direction, all outer contours of the power transmission coil are located on the inner side than all outer contours of the power receiving coil. In this case, even when a distance change or a positional deviation occurs between the power transmission coil and the power reception coil, the power transmission efficiency can be maintained high.

  More preferably, in the state where the outer peripheral length of the power transmission side shield part is smaller than the outer peripheral length of the power receiving coil and the center point of the power transmission side shield part and the center point of the power receiving coil are opposed to each other, As seen from the facing direction of the power receiving coil, all the outer contours of the power transmission side shield portion are located inside of all the outer contours of the power receiving coil. In this case, unnecessary radiation noise can be further reduced even when a change in the distance between the power transmission coil and the power reception coil or a positional deviation occurs.

More preferably, assuming that the outer peripheral length of the power transmission coil is Ls, the outer peripheral length of the power receiving coil is Lr, and the maximum separation distance between the power transmitting coil and the power receiving coil is Gmax, Ls, Lr and Gmax are expressed by the following relational expression ( 1) is satisfied.
Ls / Lr = 1−2.4462 × Ls ^−1.4193 × Gmax ± 0.05 Formula (1)
(However, the units of Ls, Lr, and Gmax in the formula are m and Ls / Lr <1.)
In this case, even when the distance between the power transmitting coil and the power receiving coil is changed or the position is shifted, the power transmission efficiency can be maintained even higher.

More preferably, the outer circumference length of the power transmission side shield part is Ws, the outer circumference length of the power reception side shield part is Wr, the maximum separation distance between the power transmission coil and the power reception coil is Gmax, and the outer circumference length of the power reception coil is Lr. Then, Ws, Wr, Gmax, Lr, and Ls satisfy the following relational expression (2).
Wr−Ws> (2.4462 × Ls− ^1.4193 × Gmax−0.05) × Lr Formula (2)
(However, the unit of Ws, Wr, Gmax, Lr, and Ls in the formula is m and Wr−Ws> 0.)
In this case, even when a change in the distance between the power transmission coil and the power reception coil or a positional deviation occurs, unnecessary radiation noise can be further reduced while maintaining the power transmission efficiency even higher.

  According to the wireless power transmission device of the present invention, it is possible to reduce unnecessary radiation noise even when the distance between the power transmission coil and the power reception coil is changed or the positional deviation occurs.

1 is a perspective view showing a wireless power transmission device according to a first embodiment of the present invention. It is a model cutting part end view of the wireless power transmission apparatus along the II line in FIG. It is a perspective view which shows the wireless power transmission apparatus which concerns on 2nd Embodiment of this invention. It is a model cutting part end view of the wireless power transmission apparatus along the II-II line in FIG. It is a graph which shows the relationship between the ratio of the outer periphery length of a power transmission coil with respect to the largest separation distance change between a power transmission coil and a power reception coil, the ratio of the outer periphery length of a power reception coil, and a coupling coefficient. It is a graph which shows the relationship between the ratio of the outer periphery length of a power transmission coil with respect to the largest separation distance change between a power transmission coil and a power reception coil, the ratio of the outer periphery length of a power reception coil, and a coupling coefficient. It is a graph which shows the relationship between the ratio of the outer periphery length of a power transmission coil with respect to the largest separation distance change between a power transmission coil and a power reception coil, the ratio of the outer periphery length of a power reception coil, and a coupling coefficient. It is a graph which shows the relationship between the ratio of the outer periphery length of a power transmission coil with respect to the largest separation distance change between a power transmission coil and a power reception coil, the ratio of the outer periphery length of a power reception coil, and a coupling coefficient. It is a graph which shows the relationship between the ratio of the outer periphery length of a power transmission coil with respect to the largest separation distance change between a power transmission coil and a power reception coil, the ratio of the outer periphery length of a power reception coil, and a coupling coefficient. It is a graph which shows the relationship between the ratio of the outer periphery length of the power transmission coil with respect to the largest separation distance change between a power transmission coil and a power reception coil, the ratio of the outer periphery length of a power reception coil, and power transmission efficiency. It is a graph which shows the relationship between the ratio of the outer periphery length of the power transmission coil with respect to the largest separation distance change between a power transmission coil and a power reception coil, the ratio of the outer periphery length of a power reception coil, and power transmission efficiency. It is a graph which shows the relationship between the ratio of the outer periphery length of the power transmission coil with respect to the largest separation distance change between a power transmission coil and a power reception coil, the ratio of the outer periphery length of a power reception coil, and power transmission efficiency. It is a graph which shows the relationship between the ratio of the outer periphery length of the power transmission coil with respect to the largest separation distance change between a power transmission coil and a power reception coil, the ratio of the outer periphery length of a power reception coil, and power transmission efficiency. It is a graph which shows the relationship between the ratio of the outer periphery length of the power transmission coil with respect to the largest separation distance change between a power transmission coil and a power reception coil, the ratio of the outer periphery length of a power reception coil, and power transmission efficiency. It is a graph which shows the ratio of the outer periphery length of the power transmission coil and the outer periphery length of a receiving coil in case the largest coupling coefficient and the coupling coefficient become the highest with respect to the largest separation distance change between a power transmission coil and a power receiving coil. It is a graph which shows the magnitude | size of the inclination of ratio of the outer periphery length of a power transmission coil, and the outer periphery length of a receiving coil with respect to the outer periphery length of a power transmission coil. It is a graph which shows the relationship between the difference of the outer periphery length of a power transmission side shield part and the outer periphery length of a power receiving side shield part, and an unnecessary radiation noise level. It is a perspective view which shows the wireless power transmission apparatus which concerns on the modification of this embodiment. It is a model cutting part end view of the wireless power transmission apparatus along the III-III line in FIG.

  DESCRIPTION OF EMBODIMENTS Embodiments (embodiments) for carrying out the present invention will be described in detail with reference to the drawings. In the description, the same reference numerals are used for the same elements or elements having the same function, and redundant description is omitted.

(First embodiment)
First, with reference to FIG.1 and FIG.2, the structure of 1st Embodiment of this invention is demonstrated. FIG. 1 is a perspective view showing a wireless power transmission device according to a first embodiment of the present invention. FIG. 2 is a schematic end view of the wireless power transmission device taken along line II in FIG.

  As illustrated in FIG. 1, the wireless power transmission device S1 includes a power transmission unit 10 and a power reception unit 20. The power transmission unit 10 includes a power transmission coil L1 and a power transmission side shield unit 11. The power reception side unit 20 includes a power reception coil L2 and a power reception side shield part 21. The power transmission coil L1 and the power reception coil L2 are arranged to face each other with a distance therebetween, and power is transmitted wirelessly.

  The power transmission unit 10 is disposed in the ground or near the ground. The number of turns of the power transmission coil L1 is appropriately set based on the separation distance between the power transmission coil L1 and the power reception coil L2 and the desired power transmission efficiency.

  As shown in FIG. 2, the power transmission side shield portion 11 is disposed on the opposite side of the surface of the power transmission coil L1 that faces the power receiving coil L2. The power transmission side shield unit 11 includes a power transmission side magnetic body 12 and a power transmission side conductor 13 disposed on the opposite side of the surface of the power transmission side magnetic body 12 that faces the power transmission coil L1. That is, in the facing direction of the power transmission coil L1 and the power reception coil L2, the power transmission coil L1, the power transmission side magnetic body 12, and the power transmission side conductor 13 are arranged in this order from the power reception coil L2 to the power transmission coil L1. Here, the power transmission side magnetic body 12 and the power transmission side conductor 13 may be disposed in contact with each other, and a gap or an insulator may be provided therebetween.

  The power transmission side magnetic body 12 is comprised from a magnetic body, and has the effect | action which reduces the magnetic resistance of a magnetic path and raises the magnetic coupling between coils. Examples of the magnetic material include Sendust, MnZn ferrite, and permalloy. Higher magnetic permeability and electrical resistance are preferred, and among these, MnZn ferrite is particularly preferred.

  The power transmission side magnetic body 12 is connected to the power transmission side magnetic body base 12a extending in a direction substantially orthogonal to the facing direction of the power transmission coil L1 and the power reception coil L2, and the peripheral edge of the power transmission side magnetic body base 12a. The power transmission side magnetic body protruding portion 12b has a gradient inclined in the direction of the power transmission coil L1 with respect to 12a and extends in a direction substantially parallel to the opposing direction of the power transmission coil L1 and the power reception coil L2. The edge of the power transmission side magnetic body protruding portion 12b opposite to the edge connected to the power transmission side magnetic body base 12a is located at the same position as the power transmission coil L1 in the facing direction of the power transmission coil L1 and the power reception coil L2. Or may be located at a high position (upward in the figure). The power transmission coil L1 is disposed in a space defined by the power transmission side magnetic base 12a and the power transmission side magnetic protrusion 12b.

  The power transmission side conductor 13 is comprised from a conductor, and has the effect | action which absorbs electromagnetic waves. Examples of the conductor include aluminum, copper, and silver. The conductor may be non-magnetic, and the higher the conductivity, the better.

  The power transmission side conductor 13 is connected to a power transmission side conductor base 13a extending in a direction substantially orthogonal to the facing direction of the power transmission coil L1 and the power reception coil L2, and a peripheral edge of the power transmission side conductor base 13a. The power transmission side conductor protrusion 13b has a gradient inclined in the direction of the power transmission coil L1 with respect to 13a and extends in a direction substantially parallel to the opposing direction of the power transmission coil L1 and the power reception coil L2. The edge of the power transmission side conductor protrusion 13b opposite to the edge connected to the power transmission side conductor base 13a is located at the same position as the power transmission coil L1 in the facing direction of the power transmission coil L1 and the power reception coil L2. Or may be located at a high position (upward in the figure). The power transmission coil L1 is arranged in a space defined by the power transmission side conductor base 13a and the power transmission side conductor protrusion 13b.

  The power receiving coil L2 is configured to receive power from the power transmitting coil L1, and is preferably disposed coaxially with the power transmitting coil L1. The number of turns of the power receiving coil L2 is appropriately set based on the separation distance between the power transmitting coil L1 and the power receiving coil L2 and the desired power transmission efficiency.

  As shown in FIG. 2, the power reception side shield portion 21 is disposed on the opposite side of the surface of the power reception coil L2 that faces the power transmission coil L1. The power-receiving-side shield portion 21 includes a power-receiving-side magnetic body 22 and a power-receiving-side conductor 23 disposed on the opposite side of the surface of the power-receiving-side magnetic body 22 that faces the power-receiving coil L2. That is, in the facing direction of the power transmission coil L1 and the power reception coil L2, the power reception coil L2, the power reception side magnetic body 22, and the power reception side conductor 23 are arranged in this order from the power transmission coil L1 toward the power reception coil L2. Here, the power receiving side magnetic body 22 and the power receiving side conductor 23 may be disposed in contact with each other, and a gap or an insulator may be provided therebetween.

  The power receiving side magnetic body 22 is made of a magnetic body and has an action of reducing the magnetic resistance of the magnetic path and increasing the magnetic coupling between the coils. Examples of the magnetic material include Sendust, MnZn ferrite, and permalloy. Higher magnetic permeability and electrical resistance are preferred, and among these, MnZn ferrite is particularly preferred.

  The power receiving side magnetic body 22 is connected to a power receiving side magnetic body base portion 22a extending in a direction substantially orthogonal to the facing direction of the power transmission coil L1 and the power receiving coil L2, and a peripheral edge of the power receiving side magnetic body base portion 22a. The power receiving side magnetic body protruding portion 22b has a gradient inclined in the direction of the power receiving coil L2 with respect to 22a and extends in a direction substantially parallel to the opposing direction of the power transmitting coil L1 and the power receiving coil L2. The edge of the power receiving side magnetic body protruding portion 22b opposite to the edge connected to the power receiving side magnetic base 22a is located at the same position as the power receiving coil L2 in the facing direction of the power transmitting coil L1 and the power receiving coil L2. Or may be located at a low position (downward in the figure). The power receiving coil L2 is disposed in a space defined by the power receiving side magnetic body base portion 22a and the power receiving side magnetic body protruding portion 22b.

  The power receiving side conductor 23 is made of a conductor and has an action of absorbing electromagnetic waves. Examples of the conductor include aluminum, copper, and silver. The conductor may be non-magnetic, and the higher the conductivity, the better.

  The power receiving side conductor 23 is connected to the power receiving side conductor base 23a extending in a direction substantially orthogonal to the facing direction of the power transmission coil L1 and the power receiving coil L2, and the peripheral edge of the power receiving side conductor base 23a. The power receiving side conductor protruding portion 23b has a gradient inclined in the direction of the power receiving coil L2 with respect to 23a and extends in a direction substantially parallel to the opposing direction of the power transmitting coil L1 and the power receiving coil L2. The edge of the power receiving side conductor protrusion 23b opposite to the edge connected to the power receiving side conductor base 23a is located at the same position as the power receiving coil L2 in the facing direction of the power transmitting coil L1 and the power receiving coil L2. Or may be located at a low position (downward in the figure). The power receiving coil L2 is disposed in a space defined by the power receiving side conductor base 23a and the power receiving side conductor protrusion 23b.

  Next, the dimensional relationship between the power transmission unit 10 and the power reception unit 20 will be described in detail. In the present embodiment, the outer peripheral length of the power transmission side shield part 11 is smaller than the outer peripheral length of the power reception side shield part 21. Here, “the outer peripheral length of the power transmission side shield part 11 is smaller than the outer peripheral length of the power reception side shield part 21” means that the power transmission side shield part 11 and the power reception side are viewed from the direction in which the power transmission coil L1 and the power reception coil L2 face each other. Even if the side shield portion 21 has a substantially circular shape, a substantially polygonal shape, or a substantially elliptical shape, the center point of the power transmission side shield portion 11 and the center point of the power reception side shield portion 21 are the same. In the state of being positioned so as to face each other, the equivalent diameter converted from the outer peripheral length of the power transmission side shield portion 11 is smaller than the equivalent diameter converted from the outer peripheral length of the power reception side shield portion 21. Further, in a state where the center point of the power transmission side shield part 11 and the center point of the power reception side shield part 21 are opposed to each other, the power transmission side shield part 11 has the power transmission side shield part 11 as viewed from the facing direction of the power transmission coil L1 and the power reception coil L2. All the outer contours are located on the inner side of all the outer contours of the power receiving side shield part 21. In other words, when the center point of the power transmission side shield portion 11 and the center point of the power reception side shield portion 21 are arranged to face each other, the power transmission side shield portion 11 is viewed from the opposing direction of the power transmission coil L1 and the power reception coil L2. Will overlap the power receiving side shield part 21.

  As described above, in the wireless power transmission device S <b> 1 according to the present embodiment, the outer peripheral length of the power transmission side shield unit 11 is smaller than the outer peripheral length of the power reception side shield unit 21 and the center point of the power transmission side shield unit 11. In the state where the central point of the power receiving side shield part 21 is located opposite to each other, all the outer contours of the power transmitting side shield part 11 are seen from the opposing direction of the power transmitting coil L1 and the power receiving coil L2. It is located outside all the outer contours. Therefore, even if the distance change and position shift between power transmission coil L1 and power reception coil L2 arise, unnecessary radiation noise can be reduced.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIGS. FIG. 3 is a perspective view showing a wireless power transmission device according to the second embodiment of the present invention. 4 is a schematic end view of the wireless power transmission device taken along line II-II in FIG. 3. The wireless power transmission device S2 according to the second embodiment is different from the wireless power transmission device S1 according to the first embodiment in terms of the size ratio between the power transmission coil and the power reception coil and the size ratio between the power transmission side shield part and the power reception coil. Is different. Hereinafter, a description will be given focusing on differences from the first embodiment.

  As illustrated in FIGS. 3 and 4, the wireless power transmission device S <b> 2 includes a power transmission unit 100 and a power reception unit 200. The power transmission unit 100 includes a power transmission coil L11 and a power transmission side shield part 110. The power receiving side unit 200 includes a power receiving coil L12 and a power receiving side shield part 210. The power transmission coil L11 and the power reception coil L12 are arranged facing each other with a distance therebetween, and power is transmitted wirelessly.

  Next, the dimensional relationship between the power transmission unit 100 and the power reception unit 200 will be described in detail. In the present embodiment, the outer peripheral length of the power transmission side shield unit 110 is smaller than the outer peripheral length of the power reception side shield unit 210 as in the wireless power transmission device S1 according to the first embodiment. However, in this embodiment, the relationship between the outer circumferential length of the power transmission coil L11 and the outer circumferential length of the power receiving coil L12 and the relationship between the outer circumferential length of the power transmission side shield unit 110 and the outer circumferential length of the power receiving coil L12 are the same as those in the first embodiment. Is different.

  In this embodiment, the outer peripheral length of the power transmission coil L11 is smaller than the outer peripheral length of the power receiving coil L12. Here, “the outer peripheral length of the power transmission coil L11 is smaller than the outer peripheral length of the power reception coil L12” means that the power transmission coil L11 and the power reception coil L12 have a substantially circular shape when viewed from the opposing direction of the power transmission coil L11 and the power reception coil L12. The outer periphery of the power transmission coil L11 in a state where the center point of the power transmission coil L11 and the center point of the power reception coil L12 are opposed to each other, regardless of whether they have a substantially polygonal shape or a substantially elliptical shape. The equivalent diameter converted from the length is smaller than the equivalent diameter converted from the outer peripheral length of the power receiving coil L12. Further, in a state where the center point of the power transmission coil L11 and the center point of the power reception coil L12 are opposed to each other, all the outer contours of the power transmission coil L11 are received by power when viewed from the facing direction of the power transmission coil L11 and the power reception coil L12. It is located inside the entire outer contour of the coil L12.

  Furthermore, in this embodiment, the outer periphery length of the power transmission side shield part 110 is smaller than the outer periphery length of the receiving coil L12. Here, “the outer peripheral length of the power transmission side shield part 110 is smaller than the outer peripheral length of the power reception coil L12” means that the power transmission side shield part 110 and the power reception coil L12 are viewed from the opposing direction of the power transmission coil L11 and the power reception coil L12. In the state where the center point of the power transmission side shield part 110 and the center point of the power receiving coil L12 are opposed to each other, even if it has a substantially circular shape, a substantially polygonal shape, or a substantially elliptical shape The equivalent diameter converted from the outer peripheral length of the power transmission side shield part 110 is smaller than the equivalent diameter converted from the outer peripheral length of the power receiving coil L12. Further, in a state where the center point of the power transmission side shield part 110 and the center point of the power reception coil L12 are opposed to each other, when viewed from the facing direction of the power transmission coil L11 and the power reception coil L12, all the power transmission side shield parts 110 The outer contour is positioned inside all the outer contours of the power receiving coil L12.

  Next, with reference to FIGS. 5 to 8, a preferable ratio of the outer peripheral length of the power transmission coil L11 and the outer peripheral length of the power receiving coil L12 will be described in detail. 5a to 5e are graphs showing the relationship between the coupling coefficient and the ratio of the outer circumference length of the power transmission coil to the outer circumference length of the power reception coil and the coupling coefficient with respect to the change in the maximum separation distance between the power transmission coil and the power reception coil. 6A to 6E are graphs showing the relationship between the power transmission efficiency and the ratio of the outer peripheral length of the power transmitting coil to the outer peripheral length of the power receiving coil with respect to the change in the maximum separation distance between the power transmitting coil and the power receiving coil. FIG. 7 is a graph showing the maximum coupling coefficient and the ratio of the outer peripheral length of the power transmitting coil to the outer peripheral length of the power receiving coil when the coupling coefficient is the highest with respect to the maximum change in the separation distance between the power transmitting coil and the power receiving coil. is there. FIG. 8 is a graph showing the magnitude of the gradient of the ratio of the outer peripheral length of the power transmission coil to the outer peripheral length of the power receiving coil with respect to the outer peripheral length of the power transmission coil.

  First, the outer peripheral length of the power transmission coil L11 is Ls (m), the outer peripheral length of the power reception coil L12 is Lr (m), and the maximum separation distance between the power transmission coil L11 and the power reception coil L12 is Gmax (m). In the present embodiment, since the outer peripheral length Ls of the power transmission coil L11 is smaller than the outer peripheral length Lr of the power receiving coil L12, the outer peripheral length Ls of the power transmitting coil L11 and the outer peripheral length Lr of the power receiving coil L12. The ratio Ls / Lr is less than 1.

  In the graph shown in FIG. 5A, the ratio Ls / Lr between the outer peripheral length Ls of the power transmission coil L11 and the outer peripheral length Lr of the power receiving coil L12 is displayed on the horizontal axis, and the coupling coefficient k is displayed on the vertical axis. In the example shown in FIG. 5a, the outer peripheral length Ls of the power transmission coil L11 is set to 1.2 m, the outer peripheral length Lr of the power receiving coil L12 is changed, and the maximum separation between the power transmitting coil L11 and the power receiving coil L12 is achieved. The distance Gmax (m) was measured while being changed to 0.05 m, 0.10 m, 0.15 m, 0.20 m, 0.25 m, and 0.30 m. From the measurement results, as the maximum separation distance Gmax (m) between the power transmission coil L11 and the power reception coil L12 increases, the coupling coefficient k becomes the highest when the outer peripheral length Ls of the power transmission coil L11 and the power reception coil L12 are increased. It was confirmed that the ratio Ls / Lr of the outer peripheral length Lr was in the range of 0.45 to 0.93, that is, when the outer peripheral length Ls of the power transmission coil L11 was smaller than the outer peripheral length Lr of the power receiving coil L12. .

  In the graph shown in FIG. 5B, the ratio Ls / Lr between the outer peripheral length Ls of the power transmission coil L11 and the outer peripheral length Lr of the power receiving coil L12 is displayed on the horizontal axis, and the coupling coefficient k is displayed on the vertical axis. In the example shown in FIG. 5b, the outer peripheral length Ls of the power transmission coil L11 is set to 1.6 m, the outer peripheral length Lr of the power receiving coil L12 is changed, and the maximum separation between the power transmitting coil L11 and the power receiving coil L12 is achieved. The distance Gmax (m) was measured while being changed to 0.05 m, 0.10 m, 0.15 m, 0.20 m, 0.25 m, and 0.30 m. From the measurement results, as the maximum separation distance Gmax (m) between the power transmission coil L11 and the power reception coil L12 increases, the coupling coefficient k becomes the highest when the outer peripheral length Ls of the power transmission coil L11 and the power reception coil L12 are increased. It was confirmed that the ratio Ls / Lr of the outer peripheral length Lr was in the range of 0.60 to 0.95, that is, when the outer peripheral length Ls of the power transmission coil L11 was smaller than the outer peripheral length Lr of the power receiving coil L12. .

  In the graph shown in FIG. 5C, the horizontal axis indicates the ratio Ls / Lr between the outer peripheral length Ls of the power transmission coil L11 and the outer peripheral length Lr of the power receiving coil L12, and the vertical axis indicates the coupling coefficient k. In the example shown in FIG. 5c, the outer peripheral length Ls of the power transmission coil L11 is set to 2.0 m, the outer peripheral length Lr of the power receiving coil L12 is changed, and the maximum separation between the power transmitting coil L11 and the power receiving coil L12 is achieved. The distance Gmax (m) was measured while being changed to 0.05 m, 0.10 m, 0.15 m, 0.20 m, 0.25 m, and 0.30 m. From the measurement results, as the maximum separation distance Gmax (m) between the power transmission coil L11 and the power reception coil L12 increases, the coupling coefficient k becomes the highest when the outer peripheral length Ls of the power transmission coil L11 and the power reception coil L12 are increased. It was confirmed that the ratio Ls / Lr of the outer peripheral length Lr is in the range of 0.70 to 0.95, that is, the outer peripheral length Ls of the power transmission coil L11 is smaller than the outer peripheral length Lr of the power receiving coil L12. .

  In the graph shown in FIG. 5d, the ratio Ls / Lr between the outer peripheral length Ls of the power transmission coil L11 and the outer peripheral length Lr of the power receiving coil L12 is displayed on the horizontal axis, and the coupling coefficient k is displayed on the vertical axis. In the example shown in FIG. 5d, the outer peripheral length Ls of the power transmission coil L11 is set to 2.4 m, the outer peripheral length Lr of the power receiving coil L12 is changed, and the maximum separation between the power transmitting coil L11 and the power receiving coil L12 is achieved. The distance Gmax (m) was measured while being changed to 0.05 m, 0.10 m, 0.15 m, 0.20 m, 0.25 m, and 0.30 m. From the measurement results, as the maximum separation distance Gmax (m) between the power transmission coil L11 and the power reception coil L12 increases, the coupling coefficient k becomes the highest when the outer peripheral length Ls of the power transmission coil L11 and the power reception coil L12 are increased. It was confirmed that the ratio Ls / Lr of the outer peripheral length Lr was in the range of 0.77 to 0.98, that is, the outer peripheral length Ls of the power transmission coil L11 was smaller than the outer peripheral length Lr of the power receiving coil L12. .

  The graph shown in FIG. 5e displays the ratio Ls / Lr between the outer peripheral length Ls of the power transmission coil L11 and the outer peripheral length Lr of the power receiving coil L12 on the horizontal axis, and the coupling coefficient k on the vertical axis. In the example shown in FIG. 5e, the outer peripheral length Ls of the power transmission coil L11 is set to 3.2 m, the outer peripheral length Lr of the power receiving coil L12 is changed, and the maximum separation between the power transmitting coil L11 and the power receiving coil L12 is achieved. The distance Gmax (m) was measured while being changed to 0.05 m, 0.10 m, 0.15 m, 0.20 m, 0.25 m, and 0.30 m. From the measurement results, as the maximum separation distance Gmax (m) between the power transmission coil L11 and the power reception coil L12 increases, the coupling coefficient k becomes the highest when the outer peripheral length Ls of the power transmission coil L11 and the power reception coil L12 are increased. It was confirmed that the ratio Ls / Lr of the outer peripheral length Lr was in the range of 0.84 to 0.99, that is, the outer peripheral length Ls of the power transmission coil L11 was smaller than the outer peripheral length Lr of the power receiving coil L12. .

  The graph shown in FIG. 6a displays the ratio Ls / Lr between the outer peripheral length Ls of the power transmission coil L11 and the outer peripheral length Lr of the power receiving coil L12 on the horizontal axis, and the power transmission efficiency η (%) on the vertical axis. Yes. In the example shown in FIG. 6a, the outer peripheral length Ls of the power transmission coil L11 is set to 1.2 m, the outer peripheral length Lr of the power receiving coil L12 is changed, and the maximum separation between the power transmitting coil L11 and the power receiving coil L12 is achieved. The distance Gmax (m) was measured while being changed to 0.05 m, 0.10 m, 0.15 m, 0.20 m, 0.25 m, and 0.30 m. From the measurement results, as the maximum separation distance Gmax (m) between the power transmission coil L11 and the power reception coil L12 increases, the power transmission efficiency η (%) becomes the highest as the outer peripheral length Ls of the power transmission coil L11. The ratio Ls / Lr of the outer peripheral length Lr of the power receiving coil L12 is in the range of 0.45 to 0.93, that is, the outer peripheral length Ls of the power transmitting coil L11 is smaller than the outer peripheral length Lr of the power receiving coil L12. Was confirmed. In the example shown in FIG. 6a, the ratio Ls / Lr between the outer peripheral length Ls of the power transmission coil L11 and the outer peripheral length Lr of the power receiving coil L12 where the power transmission efficiency η (%) is highest, in other words, the example shown in FIG. Even if the ratio Ls / Lr between the outer peripheral length Ls of the power transmission coil L11 and the outer peripheral length Lr of the power receiving coil L12, which has the highest coupling coefficient k, changes about ± 0.05, the power transmission efficiency η (%) changes. It was also confirmed that it was not recognized.

  The graph shown in FIG. 6b shows the ratio Ls / Lr between the outer peripheral length Ls of the power transmission coil L11 and the outer peripheral length Lr of the power receiving coil L12 on the horizontal axis, and the power transmission efficiency η (%) on the vertical axis. Yes. In the example shown in FIG. 6b, the outer peripheral length Ls of the power transmission coil L11 is set to 1.6 m, the outer peripheral length Lr of the power receiving coil L12 is changed, and the maximum separation between the power transmitting coil L11 and the power receiving coil L12 is achieved. The distance Gmax (m) was measured while being changed to 0.05 m, 0.10 m, 0.15 m, 0.20 m, 0.25 m, and 0.30 m. From the measurement results, as the maximum separation distance Gmax (m) between the power transmission coil L11 and the power reception coil L12 increases, the power transmission efficiency η (%) becomes the highest as the outer peripheral length Ls of the power transmission coil L11. The ratio Ls / Lr of the outer peripheral length Lr of the power receiving coil L12 is in the range of 0.6 to 0.95, that is, the outer peripheral length Ls of the power transmitting coil L11 is smaller than the outer peripheral length Lr of the power receiving coil L12. Was confirmed. In the example shown in FIG. 6b, the ratio Ls / Lr between the outer peripheral length Ls of the power transmission coil L11 and the outer peripheral length Lr of the power receiving coil L12 where the power transmission efficiency η (%) is highest, in other words, the example shown in FIG. 5b. Even if the ratio Ls / Lr between the outer peripheral length Ls of the power transmission coil L11 and the outer peripheral length Lr of the power receiving coil L12, which has the highest coupling coefficient k, changes about ± 0.05, the power transmission efficiency η (%) changes. It was also confirmed that it was not recognized.

  The graph shown in FIG. 6c shows the ratio Ls / Lr between the outer peripheral length Ls of the power transmission coil L11 and the outer peripheral length Lr of the power receiving coil L12 on the horizontal axis, and the power transmission efficiency η (%) on the vertical axis. Yes. In the example shown in FIG. 6c, the outer peripheral length Ls of the power transmission coil L11 is set to 2.0 m, the outer peripheral length Lr of the power receiving coil L12 is changed, and the maximum separation between the power transmitting coil L11 and the power receiving coil L12 is achieved. The distance Gmax (m) was measured while being changed to 0.05 m, 0.10 m, 0.15 m, 0.20 m, 0.25 m, and 0.30 m. From the measurement results, as the maximum separation distance Gmax (m) between the power transmission coil L11 and the power reception coil L12 increases, the power transmission efficiency η (%) becomes the highest as the outer peripheral length Ls of the power transmission coil L11. The ratio Ls / Lr of the outer peripheral length Lr of the power receiving coil L12 is in the range of 0.70 to 0.95, that is, the outer peripheral length Ls of the power transmitting coil L11 is smaller than the outer peripheral length Lr of the power receiving coil L12. Was confirmed. In the example shown in FIG. 6c, the ratio Ls / Lr between the outer peripheral length Ls of the power transmission coil L11 and the outer peripheral length Lr of the power receiving coil L12 that maximizes the power transmission efficiency η (%), in other words, the example shown in FIG. Even if the ratio Ls / Lr between the outer peripheral length Ls of the power transmission coil L11 and the outer peripheral length Lr of the power receiving coil L12, which has the highest coupling coefficient k, changes about ± 0.05, the power transmission efficiency η (%) changes. It was also confirmed that it was not recognized.

  The graph shown in FIG. 6d displays the ratio Ls / Lr between the outer peripheral length Ls of the power transmission coil L11 and the outer peripheral length Lr of the power receiving coil L12 on the horizontal axis, and the power transmission efficiency η (%) on the vertical axis. Yes. In the example shown in FIG. 6d, the outer peripheral length Ls of the power transmission coil L11 is set to 2.4 m, the outer peripheral length Lr of the power receiving coil L12 is changed, and the maximum separation between the power transmitting coil L11 and the power receiving coil L12 is achieved. The distance Gmax (m) was measured while being changed to 0.05 m, 0.10 m, 0.15 m, 0.20 m, 0.25 m, and 0.30 m. From the measurement results, as the maximum separation distance Gmax (m) between the power transmission coil L11 and the power reception coil L12 increases, the power transmission efficiency η (%) becomes the highest as the outer peripheral length Ls of the power transmission coil L11. The ratio Ls / Lr of the outer peripheral length Lr of the power receiving coil L12 is in the range of 0.77 to 0.98, that is, the outer peripheral length Ls of the power transmitting coil L11 is smaller than the outer peripheral length Lr of the power receiving coil L12. Was confirmed. In the example shown in FIG. 6d, the ratio Ls / Lr between the outer peripheral length Ls of the power transmission coil L11 and the outer peripheral length Lr of the power receiving coil L12 where the power transmission efficiency η (%) is highest, in other words, the example shown in FIG. Even if the ratio Ls / Lr between the outer peripheral length Ls of the power transmission coil L11 and the outer peripheral length Lr of the power receiving coil L12, which has the highest coupling coefficient k, changes about ± 0.05, the power transmission efficiency η (%) changes. It was also confirmed that it was not recognized.

  The graph shown in FIG. 6e displays the ratio Ls / Lr between the outer peripheral length Ls of the power transmission coil L11 and the outer peripheral length Lr of the power receiving coil L12 on the horizontal axis, and the power transmission efficiency η (%) on the vertical axis. Yes. In the example shown in FIG. 6e, the outer peripheral length Ls of the power transmission coil L11 is set to 3.2. m, the outer peripheral length Lr of the power receiving coil L12 is changed, and the maximum separation distance Gmax (m) between the power transmitting coil L11 and the power receiving coil L12 is 0.05 m, 0.10 m, 0.15 m, 0 .20 m, 0.25 m, and 0.30 m. From the measurement results, as the maximum separation distance Gmax (m) between the power transmission coil L11 and the power reception coil L12 increases, the power transmission efficiency η (%) becomes the highest as the outer peripheral length Ls of the power transmission coil L11. The ratio Ls / Lr of the outer peripheral length Lr of the power receiving coil L12 is in the range of 0.84 to 0.99, that is, the outer peripheral length Ls of the power transmitting coil L11 is smaller than the outer peripheral length Lr of the power receiving coil L12. Was confirmed. In the example shown in FIG. 6e, the ratio Ls / Lr between the outer peripheral length Ls of the power transmission coil L11 and the outer peripheral length Lr of the power receiving coil L12 where the power transmission efficiency η (%) is highest, in other words, the example shown in FIG. Even if the ratio Ls / Lr between the outer peripheral length Ls of the power transmission coil L11 and the outer peripheral length Lr of the power receiving coil L12, which has the highest coupling coefficient k, changes about ± 0.05, the power transmission efficiency η (%) changes. It was also confirmed that it was not recognized.

  In the graph shown in FIG. 7, the horizontal axis indicates the maximum separation distance Gmax (m) between the power transmission coil L11 and the power reception coil L12, and the vertical axis indicates the coupling coefficient k, the outer peripheral length Ls of the power transmission coil L11, and the power reception coil. The ratio Ls / Lr of the outer peripheral length Lr of L12 is displayed. In the example shown in FIG. 7, the outer peripheral length Ls of the power transmission coil L11 is set to 1.2 m, 1.6 m, 2.0 m, 2.4 m, and 3.2 m, respectively, and the outer peripheral length Lr of the power receiving coil L12 is set. And the maximum separation distance Gmax (m) between the power transmission coil L11 and the power reception coil L12 is changed to 0.05 m, 0.10 m, 0.15 m, 0.20 m, 0.25 m, and 0.30 m. And the ratio Ls / Lr of the outer peripheral length Ls of the power transmission coil L11 and the outer peripheral length Lr of the power receiving coil L12 where the coupling coefficient k is the highest. As shown in FIG. 7, the outer peripheral length Ls of the power transmission coil L11 and the power reception coil L12 having the highest coupling coefficient k with respect to the maximum separation distance Gmax (m) between the power transmission coil L11 and the power reception coil L12. The ratio Ls / Lr of the outer peripheral length Lr shows a proportional relationship in which the vertical axis intercept value is 1 and the slope is negative.

When the outer peripheral length Ls of the power transmission coil L11 is 1.2 m, an approximate straight line of the ratio Ls / Lr between the outer peripheral length Ls of the power transmission coil L11 and the outer peripheral length Lr of the power receiving coil L12 that has the highest coupling coefficient k is obtained. The ratio Ls / Lr between the outer peripheral length Ls of the power transmission coil L11 and the outer peripheral length Lr of the power reception coil L12 with respect to the maximum separation distance Gmax (m) between the power transmission coil L11 and the power reception coil L12 is expressed by the following relational expression (3 ) Will be satisfied. As described above, even if the ratio Ls / Lr between the outer peripheral length Ls of the power transmission coil L11 and the outer peripheral length Lr of the power receiving coil L12 changes by about ± 0.05, a change in the power transmission efficiency η (%) is recognized. Therefore, the allowable range of the ratio Ls / Lr between the outer peripheral length Ls of the power transmission coil L11 and the outer peripheral length Lr of the power receiving coil L12 is set.
Ls / Lr = 1−Gmax × 1.82 ± 0.05 Formula (3)
(However, the units of Ls, Lr, and Gmax in the formula are m and Ls / Lr <1.)

When the outer peripheral length Ls of the power transmission coil L11 is 1.6 m, an approximate straight line of the ratio Ls / Lr between the outer peripheral length Ls of the power transmission coil L11 and the outer peripheral length Lr of the power receiving coil L12 with the highest coupling coefficient k is obtained. The ratio Ls / Lr between the outer peripheral length Ls of the power transmission coil L11 and the outer peripheral length Lr of the power reception coil L12 with respect to the maximum separation distance Gmax (m) between the power transmission coil L11 and the power reception coil L12 is expressed by the following relational expression (4 ) Will be satisfied. As described above, even if the ratio Ls / Lr between the outer peripheral length Ls of the power transmission coil L11 and the outer peripheral length Lr of the power receiving coil L12 changes by about ± 0.05, a change in the power transmission efficiency η (%) is recognized. Therefore, the allowable range of the ratio Ls / Lr between the outer peripheral length Ls of the power transmission coil L11 and the outer peripheral length Lr of the power receiving coil L12 is set.
Ls / Lr = 1−Gmax × 1.256 ± 0.05 Formula (4)
(However, the units of Ls, Lr, and Gmax in the formula are m and Ls / Lr <1.)

When the outer peripheral length Ls of the power transmission coil L11 is 2.0 m, an approximate straight line of the ratio Ls / Lr between the outer peripheral length Ls of the power transmission coil L11 and the outer peripheral length Lr of the power receiving coil L12 that has the highest coupling coefficient k is obtained. The ratio Ls / Lr between the outer peripheral length Ls of the power transmission coil L11 and the outer peripheral length Lr of the power reception coil L12 with respect to the maximum separation distance Gmax (m) between the power transmission coil L11 and the power reception coil L12 is expressed by the following relational expression (5 ) Will be satisfied. As described above, even if the ratio Ls / Lr between the outer peripheral length Ls of the power transmission coil L11 and the outer peripheral length Lr of the power receiving coil L12 changes by about ± 0.05, a change in the power transmission efficiency η (%) is recognized. Therefore, the allowable range of the ratio Ls / Lr between the outer peripheral length Ls of the power transmission coil L11 and the outer peripheral length Lr of the power receiving coil L12 is set.
Ls / Lr = 1−Gmax × 0.9396 ± 0.05 Formula (5)
(However, the units of Ls, Lr, and Gmax in the formula are m and Ls / Lr <1.)

When the outer peripheral length Ls of the power transmission coil L11 is 2.4 m, an approximate straight line of the ratio Ls / Lr between the outer peripheral length Ls of the power transmission coil L11 and the outer peripheral length Lr of the power receiving coil L12 with the highest coupling coefficient k is obtained. The ratio Ls / Lr between the outer peripheral length Ls of the power transmission coil L11 and the outer peripheral length Lr of the power reception coil L12 with respect to the maximum separation distance Gmax (m) between the power transmission coil L11 and the power reception coil L12 is expressed by the following relational expression (6 ) Will be satisfied. As described above, even if the ratio Ls / Lr between the outer peripheral length Ls of the power transmission coil L11 and the outer peripheral length Lr of the power receiving coil L12 changes by about ± 0.05, a change in the power transmission efficiency η (%) is recognized. Therefore, the allowable range of the ratio Ls / Lr between the outer peripheral length Ls of the power transmission coil L11 and the outer peripheral length Lr of the power receiving coil L12 is set.
Ls / Lr = 1−Gmax × 0.7582 ± 0.05 Formula (6)
(However, the units of Ls, Lr, and Gmax in the formula are m and Ls / Lr <1.)

When the outer peripheral length Ls of the power transmission coil L11 is 3.2 m, an approximate straight line of the ratio Ls / Lr between the outer peripheral length Ls of the power transmission coil L11 and the outer peripheral length Lr of the power receiving coil L12 with the highest coupling coefficient k is obtained. The ratio Ls / Lr of the outer peripheral length Ls of the power transmitting coil L11 and the outer peripheral length Lr of the power receiving coil L12 with respect to the maximum separation distance Gmax (m) between the power transmitting coil L11 and the power receiving coil L12 is expressed by the following relational expression (7 ) Will be satisfied. As described above, even if the ratio Ls / Lr between the outer peripheral length Ls of the power transmission coil L11 and the outer peripheral length Lr of the power receiving coil L12 changes by about ± 0.05, a change in the power transmission efficiency η (%) is recognized. Therefore, the allowable range of the ratio Ls / Lr between the outer peripheral length Ls of the power transmission coil L11 and the outer peripheral length Lr of the power receiving coil L12 is set.
Ls / Lr = 1−Gmax × 0.4436 ± 0.05 Formula (7)
(However, the units of Ls, Lr, and Gmax in the formula are m and Ls / Lr <1.)

The graph shown in FIG. 8 displays the outer peripheral length Ls of the power transmission coil L11 on the horizontal axis, and the outer peripheral length of the power transmission coil L11 with respect to the maximum separation distance Gmax (m) between the power transmission coil L11 and the power reception coil L12 on the vertical axis. The magnitude A of the inclination of the ratio Ls / Lr between the length Ls and the outer peripheral length Lr of the power receiving coil L12 is displayed. In the example shown in FIG. 8, the outer peripheral length Ls of the power transmission coil L11 is set to 1.2 m, 1.6 m, 2.0 m, 2.4 m, and 3.2 m, respectively, and the outer peripheral length Lr of the power receiving coil L12 is set. And the maximum separation distance Gmax (m) between the power transmission coil L11 and the power reception coil L12 is changed to 0.05 m, 0.10 m, 0.15 m, 0.20 m, 0.25 m, and 0.30 m. The ratio A of the ratio Ls / Lr between the outer peripheral length Ls of the power transmission coil L11 and the outer peripheral length Lr of the power receiving coil L12 that has the highest coupling coefficient k is shown. As shown in FIG. 8, the slope of the ratio Ls / Lr between the outer peripheral length Ls of the power transmission coil L11 and the outer peripheral length Lr of the power receiving coil L12 that has the highest coupling coefficient k with respect to the outer peripheral length Ls of the power transmission coil L11. The length A satisfies the following relational expression (8).
A = 2.4462 × Ls− ^1.4193 (8)
(However, the unit of Ls represents m in the formula.)

Therefore, the magnitude of the slope of the ratio Ls / Lr between the outer peripheral length Ls of the power transmission coil L11 and the outer peripheral length Lr of the power receiving coil L12 expressed in the above formulas (3) to (7) is expressed by the formula (8 When the ratio A of the ratio Ls / Lr between the outer peripheral length Ls of the power transmission coil L11 and the outer peripheral length Lr of the power receiving coil L12 with the highest coupling coefficient k expressed by (1) is substituted, the following relational expression (1 ) Will be satisfied.
Ls / Lr = 1−2.4462 × Ls ^−1.4193 × Gmax ± 0.05 Formula (1)
(However, the units of Ls, Lr, and Gmax in the formula are m and Ls / Lr <1.)
That is, when the ratio Ls / Lr between the outer peripheral length Ls of the power transmission coil L11 and the outer peripheral length Lr of the power receiving coil L12 satisfies the above-described equation (1), the coupling coefficient k is the highest, so the power transmitting coil L11 and the power receiving coil Even in the case where a change in the distance from L12 or a positional deviation occurs, the power transmission efficiency can be maintained even higher.

  Next, a preferable dimensional relationship between the power transmission side shield part 110 and the power reception side shield part 210 will be described in detail with reference to FIG. FIG. 9 is a graph showing the relationship between the difference between the outer peripheral length Ws of the power transmission side shield part 110 and the outer peripheral length Wr of the power reception side shield part 210 and the unnecessary radiation noise level (dBμV / m).

  First, the outer circumference length of the power transmission coil L11 is Ls (m), the outer circumference length of the power reception coil L12 is Lr (m), the outer circumference length of the power transmission side shield part 110 is Ws (m), and the outer circumference of the power reception side shield part 210. The length is Wr (m), the difference between the outer peripheral length Ls of the power transmission coil L11 and the outer peripheral length Ws of the power transmission side shield part 110 is α (m), the outer peripheral length Lr of the power reception coil L12 and the power reception side shield part 210 The difference in the outer peripheral length Wr is β (m), and the maximum separation distance between the power transmission coil L11 and the power reception coil L12 is Gmax (m). In the present embodiment, since the outer peripheral length Ws of the power transmission side shield part 110 is smaller than the outer peripheral length Wr of the power reception side shield part 210, the outer peripheral length Ws of the power transmission side shield part 110 and the power reception side shield. The difference Wr−Ws in the outer peripheral length Wr of the portion 210 is larger than zero.

From the above relationship, the outer peripheral length Ws of the power transmission side shield unit 110 is Ws = Ls + α, and the outer peripheral length Wr of the power reception side shield unit 210 is Wr = Lr + β. Therefore, the difference between the outer peripheral length Ws of the power transmission side shield part 110 and the outer peripheral length Wr of the power reception side shield part 210 satisfies the following relational expression (9).
Wr−Ws = (Lr−Ls) + (β−α) Formula (9)
(However, the unit of Ws, Wr, Lr and Ls in the formula is m and Wr−Ws> 0.)
Here, even when the distance between the power transmission coil L11 and the power reception coil L12 is changed or the position shift occurs, the outer peripheral length Ls of the power transmission coil L11 and the power reception are required in order to keep the power transmission efficiency higher. The ratio Ls / Lr of the outer peripheral length Lr of the coil L12 needs to satisfy the above relational expression (1). Therefore, when the outer peripheral length Ls of the power transmission coil L11 is derived from the relational expression (1) and substituted into the relational expression (9), the outer peripheral length Ws of the power transmission side shield part 110 and the outer peripheral length of the power reception side shield part 210 are calculated. The difference in Wr is expressed by the following relational expression (10).
Wr−Ws = (Lr− (1-22.4462 × Ls− ^1.4193 × Gmax ± 0.05) × Lr) + (β−α) Formula (10)
(However, the units of Ws, Wr, Gmax, Lr, Ls, α, and β in the formula are m and Wr−Ws> 0.)

By the way, if the outer peripheral length Wr of the power receiving side shield part 210 is larger than the outer peripheral length Ws of the power transmitting side shield part 110, the effect of reducing unnecessary radiation noise can be improved. Further, the difference β between the outer peripheral length Lr of the power receiving coil L12 and the outer peripheral length Wr of the power receiving side shield part 210 is larger than the difference α between the outer peripheral length Ls of the power transmitting coil L11 and the outer peripheral length Ws of the power transmitting side shield part 110. In other words, if the relationship β> α is satisfied, unnecessary radiation noise can be further reduced. In order to reduce the influence of the inductance reduction action of the power transmission coil L11 by the power transmission side magnetic body protrusion 12b of the power transmission coil L11 and the inductance reduction action of the power reception coil L12 by the power reception side magnetic body protrusion 13b of the power reception coil L12, , Β ≠ 0 must be satisfied. From the above, as the difference between the outer peripheral length Ws of the power transmission side shield part 110 and the outer periphery length Wr of the power receiving side shield part 210 in the relational expression (10) is increased, the effect of reducing unnecessary radiation noise is improved. Can be made. Since the difference between the outer peripheral length Ws of the power transmission side shield part 110 and the outer peripheral length Wr of the power reception side shield part 210 becomes the minimum value when α = β, the distance between the power transmission coil and the power reception coil. Even when there is a change or misalignment, if it is attempted to further reduce unnecessary radiation noise while maintaining higher power transmission efficiency, the outer peripheral length Ws of the power transmission shield part 110 and the power reception shield The difference in the outer peripheral length Wr of the portion 210 satisfies the following relational expression (2).
Wr−Ws> (2.4462 × Ls− ^1.4193 × Gmax−0.05) × Lr Formula (2)
(However, the unit of Ws, Wr, Gmax, Lr, and Ls in the formula is m and Wr−Ws> 0.)

  The graph shown in FIG. 9 is a graph showing the unnecessary radiation noise level (dBμV / m) of Samples 1 and 2. Here, Sample 1 in the example shown in FIG. 9 uses a wireless power transmission device that does not satisfy the above-described relational expression (2), and Sample 2 uses a wireless power transmission apparatus S2 that satisfies the above-described relational expression (2). Unnecessary radiation noise level was measured. From the measurement results, it was confirmed that the unnecessary radiation noise level (dBμV / m) was reduced in Sample 2 compared to Sample 1. In other words, in the wireless power transmission device S2, the difference between the outer peripheral length Ws of the power transmission side shield unit 110 and the outer peripheral length Wr of the power reception side shield unit 210 satisfies the above-described relational expression (2), thereby causing unnecessary radiation noise. It was confirmed that it could be further reduced.

  As described above, in the wireless power transmission device S2 according to the present embodiment, the outer peripheral length Ws of the power transmission side shield unit 110 is smaller than the outer peripheral length Wr of the power reception side shield unit 210 and the power transmission side shield unit 110. In the state where the center point of the power receiving side and the center point of the power receiving side shield portion 210 are opposed to each other, all the outer contours of the power transmitting side shield portion 110 are seen on the power receiving side when viewed from the facing direction of the power transmitting coil L11 and the power receiving coil L12. It is located outside the entire outer contour of the shield part 210. Therefore, even if the distance change and position shift between power transmission coil L11 and power reception coil L12 arise, unnecessary radiation noise can be reduced.

  In the wireless power transmission device S2 according to the present embodiment, the outer peripheral length Ls of the power transmission coil L11 is smaller than the outer peripheral length Lr of the power receiving coil L12, and the central point of the power transmitting coil L11 and the central point of the power receiving coil L12. Are positioned so as to face each other, all the outer contours of the power transmitting coil L11 are located inside of all the outer contours of the power receiving coil L12 when viewed from the facing direction of the power transmitting coil L11 and the power receiving coil L12. . Therefore, even if the distance change or position shift between the power transmission coil L11 and the power reception coil L12 occurs, the power transmission efficiency can be maintained high.

  Further, in the wireless power transmission device S2 according to the present embodiment, the outer peripheral length Ws of the power transmission side shield unit 110 is smaller than the outer peripheral length Wr of the power receiving coil L12, and the center point of the power transmission side shield unit 110 is In a state where the center points of the power receiving coil L12 are opposed to each other, all the outer contours of the power transmission side shield unit 110 are all outer contours of the power receiving coil L12 when viewed from the facing direction of the power transmitting coil L11 and the power receiving coil L12. Is located on the inside. Therefore, even if the distance change and position shift between power transmission coil L11 and power reception coil L12 arise, unnecessary radiation noise can be further reduced.

  The preferred embodiments of the present invention have been described above. However, the present invention is not necessarily limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention. The constituent elements described include those that can be easily assumed by those skilled in the art and those that are substantially the same. Furthermore, the described constituent elements can be appropriately combined.

  For example, the power transmission side conductor 13 and the power reception side conductor 23 are not limited to those in the above embodiment. As shown in FIGS. 10 and 11, as the power transmission side conductor 13, in addition to the power transmission side conductor base 13 a and the power transmission side conductor protrusion 13 b, the power transmission side conductor 13 is connected to the peripheral edge of the power transmission side conductor protrusion 13 b, A power transmission side conductor extension 13c extending in a direction away from the power transmission coil L11 and in a direction substantially orthogonal to the facing direction of the power transmission coil L11 and the power reception coil L12 may be provided. In addition to the side conductor base portion 23a and the power receiving side conductor protruding portion 23b, it is connected to the peripheral edge of the power receiving side conductor protruding portion 23b, away from the receiving coil L12, and the facing direction of the power transmitting coil L11 and the receiving coil L12 There may be provided a power receiving side conductor extension 23c extending in a direction substantially perpendicular to the direction. In this case, the leakage magnetic flux generated from the tips of the power transmission side magnetic projection 12b and the power reception side magnetic projection 22b is offset by eddy currents generated in the power transmission side conductor extension 13c and the power reception side conductor extension 23c. Further, unnecessary radiation noise can be reduced.

  DESCRIPTION OF SYMBOLS 10,100 ... Power transmission unit 11, 110 ... Power transmission side shield part, 12 ... Power transmission side magnetic body, 12a ... Power transmission side magnetic body base part, 12b ... Power transmission side magnetic body protrusion part, 13 ... Power transmission side conductor, 13a ... Power transmission Side conductor base, 13b ... Power transmission side conductor protrusion, 13c ... Power transmission side conductor extension, 20, 200 ... Power reception unit, 21, 210 ... Power reception side shield, 22 ... Power reception side magnetic body, 22a ... Power reception side Magnetic base, 22b ... Power receiving side magnetic protrusion, 23 ... Power receiving side conductor, 23a ... Power receiving side conductor base, 23b ... Power receiving side conductor protrusion, 23c ... Power receiving side conductor extension, A ... Power transmission coil Of the ratio of the outer peripheral length of the power receiving coil and the outer peripheral length of the power receiving coil, Gmax: maximum separation distance, L1, L11: power transmitting coil, L2, L12: power receiving coil, Ls: outer peripheral length of the power transmitting coil, Lr: power receiving Coil outer circumference , S1, S2 ... wireless power transmission apparatus, Ws ... power-transmission-side shield portion outer peripheral length of, Wr ... power-receiving-side shield portion outer peripheral length of the.

Claims (5)

A device in which power is transmitted wirelessly by facing a power transmission coil and a power reception coil,
The power transmission coil;
A power transmission side shield portion disposed on the opposite side of the surface facing the power receiving coil of the power transmission coil;
The power receiving coil;
A power receiving side shield portion disposed on the opposite side of the surface facing the power transmitting coil of the power receiving coil,
The outer peripheral length of the power transmission side shield part is smaller than the outer peripheral length of the power reception side shield part, and the central point of the power transmission side shield part and the central point of the power reception side shield part are positioned so as to face each other The wireless power transmission device in which all outer contours of the power transmission side shield portion are located inside all outer contours of the power reception side shield portion when viewed from the opposing direction of the power transmission coil and the power reception coil .   In the state where the outer peripheral length of the power transmitting coil is smaller than the outer peripheral length of the power receiving coil and the center point of the power transmitting coil and the center point of the power receiving coil are opposed to each other, the power transmitting coil and the power receiving coil 2. The wireless power transmission device according to claim 1, wherein all outer contours of the power transmission coil are located on an inner side than all outer contours of the power receiving coil as viewed from a direction facing the coil.   In the state where the outer peripheral length of the power transmission side shield portion is smaller than the outer peripheral length of the power receiving coil and the center point of the power transmission side shield portion and the center point of the power receiving coil are opposed to each other, 3. The wireless power transmission device according to claim 2, wherein all outer contours of the power transmission side shield portion are located on an inner side than all outer contours of the power receiving coil as viewed from a facing direction of the coil and the power receiving coil. . When the outer peripheral length of the power transmission coil is Ls, the outer peripheral length of the power receiving coil is Lr, and the maximum separation distance between the power transmitting coil and the power receiving coil is Gmax, Ls, Lr and Gmax are expressed by the following relational expression ( The wireless power transmission device according to claim 2 or 3, which satisfies 1).
Ls / Lr = 1−2.4462 × Ls ^−1.4193 × Gmax ± 0.05 Formula (1)
(However, the units of Ls, Lr, and Gmax in the formula are m and Ls / Lr <1.) The outer circumference length of the power transmission side shield part is Ws, the outer circumference length of the power reception side shield part is Wr, the maximum separation distance between the power transmission coil and the power reception coil is Gmax, and the outer circumference length of the power reception coil is Lr. Then, Ws, Wr, Gmax, and Lr satisfy | fill the following relational expression (2), The wireless power transmission apparatus of Claim 4.
Wr−Ws> (2.4462 × Ls− ^1.4193 × Gmax−0.05) × Lr Formula (2)
(However, the unit of Ws, Wr, Gmax, Lr, and Ls in the formula is m and Wr−Ws> 0.)

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