WO2014132115A2

WO2014132115A2 - Power transmitter, power receiver, and power transfer system

Info

Publication number: WO2014132115A2
Application number: PCT/IB2014/000201
Authority: WO
Inventors: Shinji Ichikawa; Masayuki Komatsu; Shigeru Abe; Hiroyoshi Kaneko; Yukiya SATOU
Original assignee: Toyota Jidosha Kabushiki Kaisha; National University Corporation Saitama University
Priority date: 2013-02-26
Filing date: 2014-02-26
Publication date: 2014-09-04
Also published as: JP2014166070A; WO2014132115A3

Abstract

A power transmitter includes a power transmitting coil (62) that transmits power contactlessly to a power receiving coil in a state opposing the power receiving coil, and that is provided surrounding a winding axis (01) that extends in a second direction (DR2) that intersects a first direction (DR1) that is a direction opposing the power receiving coil; and a magnetic member (320) that is arranged in at least one of i) a position on an opposite side from a side that opposes the power receiving coil when viewed from the power transmitting coil (62), and ii) a position to an outside of an outer edge of the power transmitting coil (62) when the power transmitting coil (62) is viewed from above in the first direction (DR1).

Description

POWER TRANSMITTER, POWER RECEIVER, AND POWER TRANSFER

SYSTEM

BACKGROUND OF THE INVENTION

1. Field of the Invention

[0001] The invention relates to a power transmitter, a power receiver, and a power transfer system. 2. Description of Related Art

[0002] Hybrid vehicles and electric vehicles are known. Such vehicles that are powered partly or entirely by electricity (collectively referred to simply as "electric vehicles" in this specification) are equipped with a battery, and the wheels are driven using electric power (simply referred to as "power" in this specification). In recent years, technology has been developed that charges the battery contactlessly using a coil.

[0003] Japanese Patent Application Publication No. 2012-204469 (JP 2012-204469 A) describes an invention that relates to a coil device for supplying power contactlessly. This coil device for supplying power contactlessly includes a coil main body, a resin case main body within which the coil main body is housed, and a nonmagnetic conductive plate for magnetic shielding that is fixed to the case main body. JP 2012-204469 A states that a leakage magnetic field can be shielded by arranging a conductor with nonmagnetic and good conductive properties, such as an aluminum plate, on a back surface of the coil.

SUMMARY OF THE INVENTION

[0004] In view of the issue described above, the invention provides a power transmitter, a power receiver, and a power transfer system, capable of reducing the occurrence of a leakage magnetic field compared with related art.

[0005] Therefore, a first aspect of the invention relates to a power transmitter that includes a power transmitting coil and a magnetic member that are described below. The power transmitting coil transmits power contactlessly to a power receiving coil in a state opposing the power receiving coil, and the power transmitting coil is provided surrounding a winding axis that extends in a second direction that intersects a first direction. The first direction is a direction opposing the power receiving coil. The magnetic member is arranged in at least one of i) a position on an opposite side from a side that opposes the power receiving coil when viewed from the power transmitting coil, and ii) a position to an outside of an outer edge of the power transmitting coil when the power transmitting coil is viewed from above in the first direction.

[0006] Also, in the power transmitter described above, the magnetic member may include a back surface portion that is positioned on the opposite side from the side that opposes the power receiving coil when the back surface portion is viewed from the power transmitting coil, and the magnetic member may further include an electromagnetic shield arranged along the second direction between the back surface portion and the power transmitting coil.

[0007] Also, in the power transmitter described above, an outer edge of the back surface portion may be positioned to an outside of an outer edge of the electromagnetic shield when the electromagnetic shield and the back surface portion are viewed from above in the first direction.

[0008] Also, in the power transmitter described above, the magnetic member may include a back surface portion that is positioned on the opposite side from the side that opposes the power receiving coil when the back surface portion is viewed from the power transmitting coil, and the magnetic member may further include an electromagnetic shield arranged along the second direction on an opposite side from the side on which the power transmitting coil is positioned when viewed from the back surface portion.

[0009] Also, in the power transmitter described above, an outer edge of the back surface portion may be positioned to an inside of an outer edge of the electromagnetic shield when the electromagnetic shield and the back surface portion are viewed from above in the first direction. [0010] Also, in the power transmitter described above, the magnetic member may include a side wall portion that is positioned to an outside of the outer edge of the power transmitting coil when the power transmitting coil is viewed from above in the first direction.

[0011] In the power transmitter described above, the side wall portion may have a portion that extends so as to intersect the second direction on at least one of one side and the other side in the second direction when the side wall portion is viewed from the power transmitting coil.

[0012] Also, in the power transmitter described above, the back surface portion may include an opening having an area that is smaller than an area of the electromagnetic shield when the electromagnetic shield is viewed from above in the first direction.

[0013] Also, in the power transmitter described above, at a drive frequency when power is being transmitted contactlessly, a relative permeability of the magnetic member may be larger than 100, and a core loss of the magnetic member may be less than 10,000 kW/m³.

[0014] A second aspect of the invention relates to a power receiver that includes a power receiving coil and a magnetic member that are described below. IThe power receiving coil receives power contactlessly from a power transmitting coil in a state opposing the power transmitting coil, and the power receiving coil is provided surrounding a winding axis that extends in a second direction that intersects a first direction. The first direction is a direction opposing the power transmitting coil. The magnetic member is arranged in at least one of i) a position on an opposite side from a side that opposes the power transmitting coil when viewed from the power receiving coil, and ii) a position to an outside of an outer edge of the power receiving coil when the power receiving coil is viewed from above in the first direction.

[0015] Also, in the power receiver described above, the magnetic member may include a back surface portion that is positioned on the opposite side from the side that opposes the power transmitting coil when viewed from the power receiving coil, and the magnetic member may further include an electromagnetic shield arranged along the second direction between the back surface portion and the power receiving coil.

[0016] Also, in the power receiver described above, an outer edge of the back surface portion may be positioned to an outside of an outer edge of the electromagnetic shield when the electromagnetic shield and the back surface portion are viewed from above in the first direction.

[0017] Also, in the power receiver described above, the magnetic member may include a back surface portion that is positioned on the opposite side from the side that opposes the power transmitting coil when the back surface portion is viewed from the power receiving coil, and the magnetic member may further include an electromagnetic shield arranged along the second direction on an opposite side from the side on which the power receiving coil is positioned when viewed from the back surface portion.

[0018] Also, in the power receiver described above, an outer edge of the back surface portion may be positioned to an inside of an outer edge of the electromagnetic shield when the electromagnetic shield and the back surface portion are viewed from above in the first direction.

[0019] Also, in the power receiver described above, the magnetic member may include a side wall portion that is positioned to an outside of the outer edge of the power receiving coil when the power receiving coil is viewed from above in the first direction.

[0020] Also, in the power receiver described above, the side wail portion may have a portion that extends so as to intersect the second direction on at least one of one side and the other side in the second direction when the side wall portion is viewed from the power receiving coil.

[0021] Also, in the power receiver described above, the back surface portion may include an opening having an area that is smaller than an area of the electromagnetic shield when the electromagnetic shield is viewed from above in the first direction.

[0022] Also, in the power receiver described above, at a drive frequency when power is being received contactlessly, a relative permeability of the magnetic member may be larger than 100, and a core loss of the magnetic member may be less than 10,000 kW/m³. [0023] A third aspect of the invention relates to a power transfer system that includes a power receiver and a power transmitter that are described below. The power receiver includes a power receiving coil. The power transmitter includes a power transmitting coil and a magnetic member that are described below. The power transmitting coil is provided surrounding a winding axis that extends in a second direction that intersects a first direction. The first direction is a direction opposing the power receiving coil. The power transmitter transmits power contactlessly to the power receiving coil in a state opposing the power receiving coil. The magnetic member is arranged in at least one of i) a position on an opposite side from a side that opposes the power receiving coil when viewed from the power transmitting coil, and ii) a position to an outside of an outer edge of the power transmitting coil when the power transmitting coil is viewed from above in the first direction.

[0024] A fourth aspect of the invention relates to a power transfer system that includes a power transmitter and a power receiver that are described below. The power transmitter includes a power transmitting coil. The power receiver includes a power receiving coil and a magnetic member that are described below. The power receiving coil is provided surrounding a winding axis that extends in a second direction that intersects a first direction. The first direction is a direction opposing the power transmitting coil. The power receiver receives power contactlessly from the power transmitting coil in a state opposing the power transmitting coil. The magnetic member is arranged in at least one of i) a position on an opposite side from a side that opposes the power transmitting coil when viewed from the power receiving coil, and ii) a position to an outside of an outer edge of the power receiving coil when the power receiving coil is viewed from above in the first direction.

[0025] As described above, the power transmitter, the power receiver, and that power transfer system make it possible to reduce the occurrence of a leakage magnetic fietd compared to the related art.

BRIEF DESCRIPTION OF THE DRAWINGS [0026] Features, advantages, and technical and industrial significance of exemplary embodiments of the invention will be described below with reference to the accompanying drawings, in which like numerals denote like elements, and wherein:

FIG. 1 is a view showing a frame format of a power transfer system according to a first example embodiment of the invention;

FIG 2 is a left side view of an electric vehicle that includes a power receiver according to the first example embodiment;

FIG 3 is an enlarged left side view of a portion of the electric vehicle that includes the power receiver according to the first example embodiment;

FIG. 4 is a bottom view of the electric vehicle that includes the power receiver according to the first example embodiment;

FIG. 5 is a perspective view of a power receiving portion of the power receiver according to the first example embodiment;

FIG. 6 is a sectional view taken along line VI - VI in FIG. 5;

FIG. 7 is a sectional view taken along line VII - VII in FIG. 5;

FIG. 8 is a plan view of the power receiving portion of the power receiver according to the first example embodiment;

FIG. 9 is a perspective view of the power receiving portion of the power receiver according to the first example embodiment, in a disassembled state;

FIG. 10 is a perspective view of a case body that can be used for the power receiving portion of the power receiver according to the example embodiment, in a disassembled state;

FIG 11 is a perspective view of a power transmitting portion of a power transmitter according to the first example embodiment;

FIG. 12 is a sectional view taken along line XII - XII in FIG 11 ;

FIG. 13 is a sectional view taken along line XIII - XIII in FIG 11;

FIG 14 is a plan view of the power transmitting portion of the power transmitter according to the first example embodiment;

FIG. 15 is a perspective view of the power transmitting portion of the power transmitter according to the first example embodiment, in a disassembled state;

FIG 16 is a perspective view of a case body that can be used for the power transmitting portion of the power transmitter according to the example embodiment, in a disassembled state;

FIG. 17 is a perspective view showing a frame format of power transfer being performed between the power receiver (i.e., the power receiving portion) and the power transmitter (i.e., the power transmitting portion) in the first example embodiment;

FIG. 18 is a sectional view showing a frame format of power transfer being performed between the power receiver (i.e., the power receiving portion) and the power transmitter (i.e., the power transmitting portion) in the first example embodiment;

FIG. 19 is another perspective view showing a frame format of power transfer being performed between the power receiver (i.e., the power receiving portion) and the power transmitter (i.e., the power transmitting portion) in the first example embodiment;

FIG 20 is a plan view of a power receiving portioa of a power receiver according to a first modified example of the first example embodiment;

FIG. 21 is a sectional view taken along line XXI - XXI in FIG. 20;

FIG 22 is a perspective view of the power receiving portion of the power receiver according to the first modified example of the first example embodiment, in a disassembled state;

FIG. 23 is a plan view of a power transmitting portion according to the first modified example of the first example embodiment;

FIG. 24 is a sectional view taken along line XXIV - XXIV in FIG. 23 ;

FIG. 25 is a perspective view of the power transmitting portion according to the first modified example of the first example embodiment, in a disassembled state;

FIG. 26 is a perspective view of a power receiving portion according to a second modified example of the first example embodiment;

FIG 27 is a sectional view taken along line XXVll - XXVII in FIG 26;

FIG 28 is a sectional view taken along line XXVIII - XXVIII in FIG 26;

FIG 29 is a perspective view of the power receiving portion according to the second modified example of the first example embodiment, in a disassembled state;

FIG. 30 is a perspective view of a power transmitting portion according to the second modified example of the first example embodiment;

FIG 31 is a sectional view taken along line XXXI - XXXI in FIG. 30;

FIG 32 is a sectional view taken along line XXXII - XXXII in FIG. 30;

FIG. 33 is a perspective view of the power transmitting portion according to the second modified example of the first example embodiment, in a disassembled state;

FIG 34 is a perspective view of a magnetic member and an electromagnetic shield used in a power receiving portion according to a third modified example of the first example embodiment;

FIG 35 is a plan view of the power receiving portion according to the third modified example of the first example embodiment;

FIG 36 is a plan view of another example of the power receiving portion according to the third modified example of the first example embodiment;

FIG. 37 is a plan view of still another example of the power receiving portion according to the third modified example of the first example embodiment;

FIG. 38 is a plan view of a power transmitting portion according to a (first) comparative example of test example 1 ;

FIG 39 is a plan view of a power transmitting portion according to a (second) comparative example of test example 1 ;

FIG 40 is a graph indicating values of magnetic flux density at positions away from a coil unit, related to test example 1 ;

FIG 41 is another graph indicating values of magnetic flux density at positions away from the coil unit, related to test example I ;

FIG. 42 is a plan view of a power transmitting portion according to test example 2;

FIG 43 is a sectional view taken along line XLIII - XLIII in FIG 42;

FIG 44 is a graph indicating values of field intensity (i.e., magnetic field strength) at positions away from the coil unit, related to test example 2;

FIG 45 is another graph indicating values of field intensity at positions away from the coil unit, related to test example 2;

FIG 46 is a plan view of a power transmitting portion according to test example 3;

FIG 47 is a graph indicating values of magnetic flux density at positions away from the coil unit in the X direction in FIG 46;

FIG 48 is a graph indicating values of magnetic flux density at positions away from the coil unit in the Y direction in FIG 46;

FIG 49 is a perspective view of a power receiving portion according to a second example embodiment of the invention;

FIG 50 is a sectional view taken along line L - L in FIG. 49;

FIG 51 is a perspective view of the power receiving portion according to the second example embodiment, in a disassembled state;

FIG 52 is a perspective view of a power transmitting portion according to the second example embodiment;

FIG. 53 is a sectional view taken along line LIII - LIII in FIG. 52;

FIG 54 is a perspective view of the power transmitting portion according to the second example embodiment, in a disassembled state;

FIG 55 is a sectional view illustrating the manner in which power transfer is performed between the power receiving portion and the power transmitting portion according to the second example embodiment;

FIG. 56 is a view of the results after measuring, by simulation, an intensity distribution of leakage magnetic field around the power transmitting portion according to the second example embodiment;

FIG. 57 is a view of the results after measuring, by simulation, the intensity distribution of leakage magnetic field around a power transmitting portion that is not provided with a magnetic member corresponding to a magnetic member 320, as a comparative example of FIG. 56;

FIG 58 is a perspective view of a power receiving portion according to a first modified example of the second example embodiment;

FIG. 59 is a sectional view taken along line LIX - LIX in FIG 58; FIG. 60 is a perspective view of a power transmitting portion according to the first modified example of the second example embodiment;

FIG. 61 is a sectional view taken along line LXI - LX1 in FIG. 60;

FIG. 62 is a perspective view of a power receiving portion according to a second modified example of the second example embodiment;

FIG. 63 is a sectional view taken along line LXIII - LXIII in FIG 62;

FIG. 64 is a perspective view of a power transmitting portion according to the second modified example of the second example embodiment; and

FIG. 65 is a sectional view taken along line LXV - LXV in FIG. 64.

DETAILED DESCRIPTION OF EMBODIMENTS

[0027] Various example embodiments of the invention will now be described with reference to the accompanying drawings. The invention is not necessarily limited to numbers and amounts and the like that are referred to in the description of the example embodiments unless otherwise specifically stated. Further, in the description of the example embodiments, like parts and corresponding parts will be denoted by like reference characters and redundant descriptions of those parts may not be repeated.

[0028] First, a first example embodiment of the invention will be described. FIG 1 is a view showing a frame format of a power transfer system 1000 according to the first example embodiment. As shown in FIG 1, the power transfer system 1000 includes an electric vehicle 10 (in this specification, an electric vehicle refers to a vehicle powered partly or entirely by electricity) and an external power supply apparatus 60.

[0029] The electric vehicle 10 includes a vehicle main body 70. The vehicle main body 70 is equipped with a power receiver 11 , a moving mechanism 30, a regulator 9, a rectifier 13, a DC / DC converter 142, a battery 150, a step up converter 162, an inverter 164, a motor-generator 172, an engine (not shown), a communication portion 160, and a controller 180.

[0030] The power receiver 11 receives power contactlessly from a power transmitter 50 of the external power supply apparatus 60, while the electric vehicle 10 is stopped in a predetermined position in a parking space 52G and the power receiver 11 is opposing the power transmitter 50. The power receiver 11 has a power receiving portion 200. This power receiving portion 200 is supported by the moving mechanism 30. The power receiving portion 200 is able to move up and down (i.e., be raised and lowered) by the moving mechanism 30 being driven. The regulator 9 regulates the amount of power supplied from the battery 150 to the moving mechanism 30. The controller 180 controls the driving of the moving mechanism 30 by sending a control signal to the regulator 9.

[0031] The power receiving portion 200 of the power receiver 1 1 includes a capacitor 23 and a coil unit 24. The coil unit 24 has a ferrite core 21 and a power receiving coil 22. The power receiving coil 22 is connected to the capacitor 23 and the rectifier 13. The power receiving coil 22 and the capacitor 23 are connected together in parallel or in series. The power receiving coil 22 has a floating capacitance. An electrical circuit (an LC resonance circuit) is formed by the inductance of the power receiving coil 22, the floating capacitance of the power receiving coil 22, and the capacitance of the capacitor 23. The capacitor 23 is not absolutely necessary, and may be used if needed.

[0032] The rectifier 13 includes a diode bridge and a smoothing capacitor, neither of which is shown. The rectifier 13 converts alternating current supplied from the power receiver 11 to direct current, and supplies this direct current to the DC / DC converter 142. The DC / DC converter 142 is connected to the battery 150. The DC / DC converter 142 regulates the voltage of the direct current supplied from the rectifier 13, and supplies this regulated voltage to the battery 150. The DC / DC converter 142 is not absolutely necessary, and may be used if needed. When the DC / DC converter 142 is not used, a matching box may be provided between the power transmitter 50 of the external power supply apparatus 60 and a high frequency power supply 56. This matching box adjusts the impedance and may be used in place of the DC / DC converter 142.

[0033] The battery 150 includes a power storing element configured to be able to charge and discharge, such as an electric double layer capacitor, or a secondary battery such as a lithium-ion battery, a nickel-metal hydride battery, or a lead battery, for example. The battery 150 enables the electric vehicle 10 to function as a hybrid vehicle. As long as the electric vehicle 10 is a vehicle that is driven by an electric motor, the electric vehicle 10 may also function as a fuel cell vehicle, or an electric vehicle (i.e., a vehicle driven entirely by electricity). In this example embodiment, the object that is to receive power is a vehicle, but the object that is to receive power may also be something other than a vehicle.

(0034 J In addition to storing the power supplied from the DC / DC converter 142, the battery 150 also stores regenerative power generated by the motor-generator 172. The battery 150 supplies the stored power to the step up converter 162. The step up converter 162 steps up the voltage of the power from the battery 150 and supplies the resultant power to the inverter 164. The inverter 164 includes a three-phase bridge circuit, for example. The inverter 164 drives the motor-generator 172 based on a signal from the controller 180.

[0035] The motor-generator 172 is an alternating current (AC) rotary electric machine, and includes a three-phase synchronous motor-generator with permanent magnets embedded in a rotor, for example. The motor-generator 172 generates power using the kinetic energy of the engine that has been split by a power split device, not shown. The electric vehicle 10 runs by driving force generated by at least one of the engine (not shown) and the motor-generator 172. For example, if a state-of-charge (SOC) of the battery 150 becomes lower than a preset value, the engine is started and power is generated by the motor-generator 172 to charge the battery 150.

[0036] FIG 2 is a left side view of the electric vehicle 10. FIG 3 is an enlarged side view of a portion of the electric vehicle 10. In FIG. 3, for the sake of simplicity, a portion of a rear fender 85L, which will be described later, is shown fractured, and the power receiver 11 (a case body 270) is indicated by a solid line. FIG 4 is a bottom view of the electric vehicle 10. In FIG 4, "D" indicates a vertically downward direction, "L" indicates a direction toward the left of the vehicle, "R" indicates a direction toward the right of the vehicle, "F" indicates vehicle advancing direction (i.e., a direction toward the front of the vehicle), and "B" indicates a vehicle reversing direction (i.e., a direction toward the rear of the vehicle).

[0037] As shown in FIGS. 2 to 4, the electric vehicle 10 includes a vehicle main body 70 and wheels 19F and 19B (see the wheels 19FL, 19FR, 19BL, and 19BR in FIG 4). A drive compartment 80T, an occupant accommodating compartment 8 IT, and a luggage compartment 82T are provided in the vehicle main body 70. The engine and the like, not shown, are housed in the drive compartment 80T.

[0038] An opening 82L for getting into and out of the vehicle main body 70, a door 83L, a front fender 84L, a front bumper 86T, a rear fender 85L, and a rear bumper 87T are provided on a left side surface 71 of the vehicle main body 70. The opening 82L for getting into and out of the vehicle main body 70 is communicated with the occupant accommodating compartment 8 IT. The door 83 L opens and closes the opening 82L for getting into and out of the vehicle main body 70. The communication portion 160 is provided on an upper portion of the vehicle main body 70. The communication portion 160 is an interface for communicating between the electric vehicle 10 and the external power supply apparatus 60 (see FIG 1).

[0039] The vehicle main body 70 has a bottom surface 76. The bottom surface 76 of the electric vehicle 10 is a visibly recognizable region of the electric vehicle 10, when the electric vehicle 10 is viewed from underneath (i.e., from a position away from the ground surface in the vertically downward direction), when the wheels 19FL, 19FR, 19RL, and 19RB of the electric vehicle 10 are contacting the ground. A floor panel 69, side members 67S, and cross member are provided on the bottom surface 76 of the electric vehicle 10. The floor panel 69 has a plate shape, and separates the inside of the electric vehicle 10 from the outside of the electric vehicle 10. The side members 67S and the cross member are arranged on a lower surface of the floor panel 69.

[0040] The case body 270 of the power receiver 11 houses the power receiving portion 200, and is supported by a moving mechanism (see the moving mechanism 30 in FIG 1), not shown. The moving mechanism is provided on the bottom surface 76 of the electric vehicle 10, for example. The power receiving portion 200 in the case body 270 is able to be raised and lowered as shown by arrow ARl in FIG. 3, by the moving mechanism being driven. The moving mechanism is not absolutely necessary. The power receiver 11 may also be fixed to the bottom surface 76 of the vehicle main body 70. The structures described in this example embodiment and other example embodiments below are able to be employed as a power receiver, a power transmitter, and a power transfer system regardless of whether the moving mechanism is provided.

[0041] When the case body 270 (i.e., the power receiving portion 200) is arranged on the bottom surface 76 of the electric vehicle 10, the case body 270 (i.e., the power receiving portion 200) is positioned between the rear wheel 19BR and the rear wheel 19BL. When the moving mechanism is used, the power receiving portion 200 may be fixed to the vehicle main body 70 in a state moved by the moving mechanism to the highest position in the vertical direction, for example. The battery 150 (see FIG 4) is arranged near the power receiver I I .

[0042] The power receiving coii 22 in this example embodiment is provided surrounding (i.e., around) a winding axis 02 (see FIG. 5) (this will be described in detail later). The winding axis 02 of the power receiving coil 22 is formed by drawing a line that passes through or near a curvature center point of the power receiving coil 22 of each unit length, when the power receiving coil 22 is divided into unit lengths from one end portion in a length direction of the power receiving coil 22 to the other end portion in the length direction of the power receiving coil 22, for example. The method for leading the winding axis 02 that is a virtual line from the curvature center point of the power receiving coil 22 of each unit length may be any of a variety of approximating methods, such as linear approximation, logarithmic approximation, and multi-term approximation, for example.

[0043] The winding axis 02 in this example embodiment has a linear shape, and is provided extending in a direction parallel to the vehicle advancing direction F. The power receiving coil 22 receives power contactlessly from the power transmitting coil 62, in a state opposing the power transmitting coil 62 (see FIG 1). When the direction in which the power receiving coil 22 and the power transmitting coil 62 oppose one another is a first direction DRl (see FIGS. 1 , 5, and 17 and the like), the winding axis 02 extends toward a second direction DR2 (see FIGS. 5 and 17 and the like) that intersects the first direction DRl. [0044] In this example embodiment, the winding axis 02 intersecting the first direction DR1 means that the winding axis 02 is orthogonal or substantially orthogonal to the first direction DR1. Substantially orthogonal includes a case in which the winding axis 02 intersects the first direction DR1 in a state offset in a range of greater than 0° to equal to or less than +15°, for example, from a state in which the winding axis 02 is orthogonal to the first direction DR1. Preferably, the winding axis 02 intersects the first direction DR1 at an angular range from 80° to 100°, inclusive. More preferably, the winding axis 02 intersects the first direction DR1 at an angular range from 85° to 95°, inclusive. Optimally, the winding axis 02 intersects the first direction DR1 at an angle of 90°. The first direction DR1 in this example embodiment is a direction perpendicular to a surface (the ground) of the parking space 52G (see FIG 1), and the winding axis 02 extends in a direction parallel to the surface (the ground) of the parking space 52G.

[0045] Next, the external power supply apparatus 60 will be described. Referring to FIG. 1 again, the external power supply apparatus 60 includes the power transmitter 50, a communication portion 52, a power transmitting ECU 54, and the high frequency power supply 56. A power transmitting portion 300 of the power transmitter 50 includes a capacitor 63 and a coil unit 64. The coil unit 64 has a ferrite core 61 and a power transmitting coil 62. The power transmitting coil 62 is electrically connected to the capacitor 63 and the high frequency power supply 56. The high frequency power supply 56 is connected to an alternating current power supply 58. The alternating current power supply 58 may be a commercial power supply or a private power supply.

[0046] The power transmitting coil 62 and the capacitor 63 are connected together in parallel or in series. The power transmitting coil 62 has a floating capacitance. An electrical circuit (an LC resonance circuit) is formed by the inductance of the power transmitting coil 62, the floating capacitance of the power transmitting coil 62, and the capacitance of the capacitor 63. The capacitor 63 is not absolutely necessary, and may be used if needed.

[0047] The power transmitting coil 62 transmits power contactlessly by electromagnetic induction to the power receiving coil 22 of the power receiving portion 200. With the power transmitting coil 62, the number of windings and the distance between coils are appropriately set such that a coupling coefficient (κ) indicative of the degree of coupling between the power transmitting coil 62 and the power receiving coil 22, and the like, comes to be an appropriate value based on the distance to the power receiving coil 22, and the frequencies of the power transmitting coil 62 and the power receiving coil 22 and the like.

[0048] The power transmitting ECU 54 includes a CPU, a storage device, and an input / output buffer. This power transmitting ECU 54 inputs signals from various sensors and the like, and outputs control signals to various devices. In addition, the power transmitting ECU 54 controls various devices in the external power supply apparatus 60. The high frequency power supply 56 is controlled by a control signal from the power transmitting ECU 54, and converts power received from the alternating current power supply 58 to high frequency power. The high frequency power supply 56 supplies the converted high frequency power to the power transmitting coil 62.

[0049] The communication portion 52 is an interface for communicating between the external power supply apparatus 60 and the electric vehicle 10 (i.e., the communication portion 160). The communication portion 52 receives signals indicative of commands for starting and stopping power transmission, and battery information and the like sent from the communication portion 160, and outputs this information and the like to the power transmitting ECU 54.

[0050] Next, the power receiving portion 200 will be described. FIG 5 is a perspective view of the power receiving portion 200 of the power receiver 11 (see FIG 1). In FIG. 5, "U" indicates a vertically upward direction, and "L", "R", "F'\ "B", and "D" indicate the same directions as they do in FIG. 4. FIG 6 is a sectional view taken along line VI - VI in FIG 5. FIG 7 is a sectional view taken along line VII - VII in FIG 5, FIG 8 is a plan view of the power receiving portion 200, and FIG 9 is a perspective view of the power receiving portion 200 in a disassembled state.

[0051] The power receiving portion 200 in this example embodiment includes an electromagnetic shield 210 and a magnetic member 220, in addition to the capacitor 23 (not shown) and the coil unit 24. As described above, the coil unit 24 includes the ferrite core 21 and the power receiving coil 22. The coil unit 24 is a so-called solenoid coil type coil unit.

[0052] The ferrite core 21 has magnetic pole portions 21 A and 21 B, and a shaft portion 21C. The ferrite core 21 has an overall H-shape when viewed from above (see FIG. 8). The shaft portion 21 C is formed in a plate shape, and has a shape that extends in the direction in which the winding axis 02 of the power receiving coil 22 extends. The power receiving coil 22 is formed surrounding the winding axis 02.

[0053] The magnetic pole portion 21 A is provided on one end portion of the shaft portion 21C in the direction in which the winding axis 02 of the power receiving coil 22 extends. The magnetic pole portion 21 A is formed in a plate shape. The magnetic pole portion 21 A has a shape that extends in a direction orthogonal or substantially orthogonal to the direction in which the winding axis 02 of the power receiving coil 22 extends. The magnetic pole portion 21 B is provided on the other end portion of the shaft portion 21 C in the direction in which the winding axis 02 of the power receiving coil 22 extends. The magnetic pole portion 21B is also formed in a plate shape. The magnetic pole portion 21 B also has a shape that extends in a direction orthogonal or substantially orthogonal to the direction in which the winding axis 02 of the power receiving coil 22 extends.

[0054] The electromagnetic shield 210 has a flat plate shape (see FIG. 9). An aluminum plate having a thickness of 1 mm, for example, may be used as the electromagnetic shield 210. The electromagnetic shield 210 is arranged on a side opposite the side where the power receiving coil 22 opposes the power transmitting coil 62 (not shown) when viewed from the power receiving coil 22.

[0055] The electromagnetic shield 210 in this example embodiment is positioned on a vertically upper side (i.e., a side in the vertically upward direction U) when viewed from the power receiving coil 22. The electromagnetic shield 210 is arranged extending in the second direction DR2. Just as described above, when the direction in which the power receiving coil 22 and the power transmitting coil 62 (not shown) oppose one another is the first direction DRl , the second direction DR2 is a direction that is orthogonal to the first direction DRl.

[0056] As shown in FIG. 8, when the electromagnetic shield 210 is viewed from above in the first direction DRl , an outer edge (the visible outline) of the electromagnetic shield 210 has a rectangular shape. The outer edge of the electromagnetic shield 210 is positioned to the outside of an outer edge of the coil unit 24 (i.e., the ferrite core 21 and the power receiving coil 22). The area of the electromagnetic shield 210 when the electromagnetic shield 210 is viewed from above in the first direction DRl is larger than the area of the coil unit 24 when the coil unit 24 is viewed from above in the first direction DRl .

[0057] The magnetic member 220 has an overall shape that is open in the vertically downward direction D, and includes a back surface portion 221 and side wall portions 222 to 225. The back surface portion 221 and side wall portions 222 to 225 all have flat plate shapes, and are fonned from so-called ferromagnetic material such as ferrite, iron dust (dust core), amorphous (amorphous core), iron oxide, chromium oxide, or cobalt, for example. When manufacturing the back surface portion 221 and the side wall portions 222 to 225, the back surface portion 221 and side wall portions 222 to 225 may be manufactured by combining a plurality of divided ferrites, or they may be manufactured by a single ferrite.

[0058] The back surface portion 221 is positioned on a side opposite the side on which the power receiving coil 22 is positioned when viewed from the electromagnetic shield 210. The back surface portion 221 is attached to the floor panel 69 (FIGS. 6 and 7), for example. The electromagnetic shield 210 extends in the second direction DR2 between the back surface portion 221 and the power receiving coil 22. When the back surface portion 221 is viewed from above in the first direction DRl , an outer edge (the visible outline) of the back surface portion 221 has a rectangular shape. When the electromagnetic shield 210 and the back surface portion 221 are viewed from above in the first direction DRl, the outer edge of the back surface portion 221 is positioned to the outside of the outer edge of the electromagnetic shield 210 (see FIG. 8). The area of the back surface portion 221 when the back surface portion 221 is viewed from above in the first direction DR1 is larger than the area of the electromagnetic shield 210 when the electromagnetic shield 210 is viewed from above in the first direction DR1.

[0059] The side wall portions 222 to 225 are arranged in an overall rectangular loop shape, and are provided hanging down on the vertically lower side (i.e., the side in the vertically downward direction D) from the outer edge of the back surface portion 221. When the side wall portions 222 to 225 and the power receiving coil 22 are viewed from above in the first direction DR1, the side wall portions 222 to 225 are positioned to the outside of the outer edge of the power receiving coil 22, and surround the power receiving coil 22 at a distance from the power receiving coil 22.

[0060] The side wall portion 222 is arranged so as to intersect the second direction DR2 (in this example embodiment, the side wall portion 222 is arranged orthogonal to the second direction DR2), on one side in the second direction DR2 when viewed from the power receiving coil 22. The side wall portion 224 is arranged so as to intersect the second direction DR2 (in this example embodiment, the side wall portion 224 is arranged orthogonal to the second direction DR2), on the other side in the second direction DR2 when viewed from the power receiving coil 22.

[0061] The side wall portions 222 and 224 in this example embodiment have plate shapes that extend so as to intersect (or be orthogonal or substantially orthogonal to) the winding axis 02. The side wall portions 222 and 224 have shapes that extend parallel to each other. The side wall portions 222 and 224 may also have plate shapes that are curved. Even if they do not have plate shapes, the side wall portions 222 and 224 may have portions that intersect or are orthogonal or substantially orthogonal to the winding axis 02. Only one of the side wall portion 222 and the side wall portion 224 may also be used for the magnetic member 220.

[0062] The side wall portions 223 and 225 are provided between the side wall portions 222 and 224 so as to form a rectangular loop shape with the side wall portions 222 and 224. The side wall portions 223 and 225 are arranged so as to sandwich the power receiving coil 22 from the outside on both sides a distance apart from the power receiving coil 22. The side wall portions 223 and 225 have shapes that extend parallel to each other. The side wall portions 223 and 225 may also have plate shapes that are curved. The side wall portions 222 to 225 may also be arranged in an overall circular shape, oval shape, or polygonal loop shape. As shown in FIGS. 6 and 7, it is preferable that the position of the lower end of the side wall portions 222 to 225 in the vertically downward direction D be positioned lower than the position of the winding axis 02 in the vertically downward direction D.

[0063] Though not shown in FIGS. 5 to 9, the coil unit 24 is preferably housed in the case body 270 (see FIG. 10). The case body 270 includes a shield portion 250 and a lid portion 260. The shield portion 250 has an overall shape that is open toward the vertically downward direction D, and includes a top plate portion 251 and peripheral wall portions 252 to 255. The top plate portion 251 and peripheral wall portions 252 to 255 each have a flat plate shape and are formed from metal material such as copper, for example.

[0064] The top plate portion 251 is arranged opposing the electromagnetic shield 210 (see FIG. 9). The top plate portion 251 is positioned on a side opposite the side on which the back, surface portion 221 of the magnetic member 220 is positioned when viewed from the electromagnetic shield 210. The top plate portion 251 extends in the second direction DR2 between the back surface portion 221 of the magnetic member 220 and the power receiving coil 22. When the top plate portion 251 is viewed from above in the first direction DRl , an outer edge (the visible outline) of the top plate portion 251 has a rectangular shape. When the top plate portion 251 and the electromagnetic shield 210 are viewed from above in the first direction DRl , the outer edge of the electromagnetic shield 210 is positioned to the outside of the outer edge of the top plate portion 251. The area of the electromagnetic shield 210 when the electromagnetic shield 210 is viewed from above in the first direction DRl is larger than the area of the top plate portion 251 when the top plate portion 251 is viewed from above in the first direction DRl .

[0065] The peripheral wall portions 252 to 255 are arranged in an overall rectangular loop shape, and are provided hanging down on the vertically lower side (i.e., the side in the vertically downward direction D) from the outer edge of the top plate portion 251. When the peripheral wall portions 252 to 255 and the power receiving coil 22 are viewed from above in the first direction DR1, the peripheral wall portions 252 to 255 are positioned to the outside of the outer edge of the power receiving coil 22, and surround the power receiving coil 22 a distance away from the power receiving coil 22 to the inside of the side wall portions 222 to 225 of the magnetic member 220. The lid portion 260 is provided blocking the opening of the shield portion 250. The lid portion 260 is made of resin or the like.

[0066] Next, the power transmitting portion 300 will be described. FIG. 11 is a perspective view of the power transmitting portion 300 of the power transmitter 50 (see FIG 1). FIG 12 is a sectional view taken along line XII - XII in FIG. 11. FIG. 13 is a sectional view taken along line XIII - XIII in FIG. 11. FIG. 14 is a plan view of the power transmitting portion 300. FIG. 15 is a perspective view of the power transmitting portion 300 in a disassembled state.

[0067] The power transmitting portion 300 in this example embodiment includes an electromagnetic shield 310 and a magnetic member 320, in addition to the capacitor 63 (not shown) and the coil unit 64. Just as described above, the coil unit 64 includes the ferrite core 61 and the power transmitting coil 62. The coil unit 64 is a so-called solenoid coil type coil unit.

[0068] The ferrite core 61 has magnetic pole portions 61 A and 6 IB, and a shaft portion 61C. The ferrite core 61 has an overall H-shape when viewed from above (see FIG. 14). The shaft portion 61C is formed in a plate shape, and has a shape that extends in the direction in which a winding axis 01 of the power transmitting coil 62 extends. The power transmitting coil 62 is formed surrounding the winding axis 01.

[0069] The magnetic pole portion 61 A is provided on one end portion of the shaft portion 61 C in the direction in which the winding axis 01 of the power transmitting coil 62 extends. The magnetic pole portion 61 A is formed in a plate shape. The magnetic pole portion 61 A has a shape that extends in a direction that intersects (or is orthogonal or substantially orthogonal to) the direction in which the winding axis 01 of the power transmitting coil 62 extends. [0070] In this example embodiment, the winding axis 01 intersecting the first direction DRl means that the winding axis 01 is orthogonal or substantially orthogonal to the first direction DRl . Substantially orthogonal includes a case in which the winding axis 01 intersects the first direction DRl in a state offset in a range of greater than 0° to equal to or less than ±15°, for example, from a state in which the winding axis 01 is orthogonal to the first direction DRl . Preferably, the winding axis 01 intersects the first direction DRl at an angular range from 80° to 100°, inclusive. More preferably, the winding axis 01 intersects the first direction DRl at an angular range from 85° to 95°, inclusive. Optimally, the winding axis 01 intersects the first direction DRl at an angle of 90°. The magnetic pole portion 61 B is provided on the other end portion of the shaft portion 61 C in the direction in which the winding axis 01 of the power transmitting coil 62 extends. The magnetic pole portion 61 B is also formed in a plate shape. The magnetic pole portion 61B also has a shape that extends in a direction intersecting (or that is orthogonal or substantially orthogonal to) the direction in which the winding axis 01 of the power transmitting coil 62 extends.

[0071] The electromagnetic shield 310 has a flat plate shape (see FIG. 15). An aluminum plate having a thickness of 1 mm, for example, may be used as the electromagnetic shield 310. The electromagnetic shield 310 is arranged on a side opposite the side where the power transmitting coil 62 opposes the power receiving coil 22 (not shown) when viewed from the power transmitting coil 62.

[0072] The electromagnetic shield 310 in this example embodiment is positioned on the vertically lower side (i.e., the side in the vertically downward direction D) when viewed from the power transmitting coil 62. The electromagnetic shield 310 is arranged extending in the second direction DR2. Just as described above, when the direction in which the power transmitting coil 62 and the power receiving coil 22 (not shown) oppose one another is the first direction DRl , the second direction DR2 is a direction that is orthogonal to the first direction DRl .

[0073] As shown in FIG 14, when the electromagnetic shield 310 is viewed from above in the first direction DRl , an outer edge (the visible outline) of the electromagnetic shield 310 has a rectangular shape. The outer edge of the electromagnetic shield 310 is positioned to the outside of an outer edge of the coil unit 64 (i.e., the ferrite core 61 and the power transmitting coil 62). The area of the electromagnetic shield 310 when the electromagnetic shield 310 is viewed from above in the first direction DRl is larger than the area of the coil unit 64 when the coil unit 64 is viewed from above in the first direction DRl .

[0074] The magnetic member 320 has an overall shape that is open in the vertically upward direction U, and includes a back surface portion 321 and side wall portions 322 to 325. The back surface portion 321 and side wall .portions 322 to 325 all have flat plate shapes, and are formed from so-called ferromagnetic material such as ferrite, iron dust (dust core), amorphous (amorphous core), iron oxide, chromium oxide, or cobalt, for example. When manufacturing the back surface portion 321 and the side wall portions 322 to 325, the back surface portion 321 and side wall portions 322 to 325 may be manufactured by combining a plurality of divided ferrites, or they may be manufactured by a single ferrite.

[0075] The back surface portion 321 is positioned on a side opposite the side on which the power transmitting coil 62 is positioned when viewed from the electromagnetic shield 310. The back surface portion 321 is attached to the ground 390 (FIGS. 12 and 13), for example. The electromagnetic shield 310 extends in the second direction DR2 between the back surface portion 321 and the power transmitting coil 62. When the back surface portion 321 is viewed from above in the first direction DRl, an outer edge (the visible outline) of the back surface portion 321 has a rectangular shape. When the electromagnetic shield 310 and the back surface portion 321 are viewed from above in the first direction DRl , the outer edge of the back surface portion 321 is positioned to the outside of the outer edge of the electromagnetic shield 310 (see FIG 14). The area of the back surface portion 321 when the back surface portion 321 is viewed from above in the first direction DRl is larger than the area of the electromagnetic shield 310 when the electromagnetic shield 310 is viewed from above in the first direction DRl .

[0076] The side wall portions 322 to 325 are arranged in an overall rectangular loop shape, and are provided rising up on the vertically upper side (i.e., the side in the vertically upward direction U) from the outer edge of the back surface portion 321. When the side wall portions 322 to 325 and the power transmitting coil 62 are viewed from above in the first direction DR1, the side wall portions 322 to 325 are positioned to the outside of the outer edge of the power transmitting coil 62, and surround the power transmitting coil 62 at a distance from the power transmitting coil 62.

[0077] The side wall portion 322 is arranged so as to intersect the second direction DR2 (in this example embodiment, the side wall portion 322 is arranged orthogonal to the second direction DR2), on one side in the second direction DR2 when viewed from the power transmitting coil 62. The side wall portion 324 is arranged so as to intersect the second direction DR2 (in this example embodiment, the side wall portion 324 is arranged orthogonal to the second direction DR2), on the other side in the second direction DR2 when viewed from the power transmitting coil 62.

[0078] The side wall portions 322 and 324 in this example embodiment have plate shapes that extend so as to intersect (or be oitliogonal or substantially orthogonal to) the winding axis 01. The side wall portions 322 and 324 have shapes that extend parallel to each other. The side wall portions 322 and 324 may also have plate shapes that are curved. Even if they do not have plate shapes, the side wall portions 322 and 324 may have portions that intersect, or are orthogonal or substantially orthogonal to, the winding axis 01. Only one of the side wall portion 322 and the side wall portion 324 may also be used for the magnetic member 320.

[0079] The side wall portions 323 and 325 are provided between the side wall portions 322 and 324 so as to form a rectangular loop shape with the side wall portions 322 and 324. The side wall portions 323 and 325 are arranged so as to sandwich the power transmitting coil 62 from the outside on both sides a distance apart from the power transmitting coil 62. The side wall portions 323 and 325 have shapes that extend parallel to each other. The side wall portions 323 and 325 may also have plate shapes that are curved. The side wall portions 322 to 325 may also be arranged in an overall circular shape, oval shape, or polygonal loop shape. As shown in FIGS. 12 and 13, it is preferable that the position of the upper end of the side wall portions 322 to 325 in the vertically upward direction U be positioned higher than the position of the winding axis 01 in the vertically upward direction U.

[0080] Though not shown in FIGS. 11 to 15, the coil unit 64 is preferably housed in a case body 370 (see FIG 16). The case body 370 includes a shield portion 350 and a lid portion 360. The shield portion 350 has an overall shape that is open toward the vertically upward direction U, and includes a bottom plate portion 351 and peripheral wall portions 352 to 355. The bottom plate portion 351 and peripheral wall portions 352 to 355 each have a flat plate shape and are formed from metal material such as copper, for example.

[0081] The bottom plate portion 351 is arranged opposing the electromagnetic shield 310 (see FIG. 15). The bottom plate portion 351 is positioned on a side opposite the side on which the back surface portion 321 of the magnetic member 320 is positioned when viewed from the electromagnetic shield 310. The bottom plate portion 351 extends in the second direction DR2 between the back surface portion 321 of the magnetic member 320 and the power transmitting coil 62. When the bottom plate portion 351 is viewed from above in the first direction DRl , an outer edge (the visible outline) of the bottom plate portion 351 has a rectangular shape. When the bottom plate portion 351 and the electromagnetic shield 310 are viewed from above in the first direction DRl, the outer edge of the electromagnetic shield 310 is positioned to the outside of the outer edge of the bottom plate portion 351. The area of die electromagnetic shield 310 when the electromagnetic shield 310 is viewed from above in the first direction DRl is larger than the area of the bottom plate portion 351 when the bottom plate portion 351 is viewed from above in the first direction DR 1.

[0082] The peripheral wall portions 352 to 355 are arranged in an overall rectangular loop shape, and are provided rising up on the vertically upper side (i.e., the side in the vertically upward direction U) from the outer edge of the bottom plate portion 351. When the peripheral wall portions 352 to 355 and the power transmitting coil 62 are viewed from above in the first direction DRl, the peripheral wall portions 352 to 355 are positioned to the outside of the outer edge of the power transmitting coil 62, and surround the power transmitting coil 62 a distance away from the power transmitting coil 62 to the inside of the side wall portions 322 to 325 of the magnetic member 320. The lid portion 360 is provided blocking the opening of the shield portion 350. The lid portion 360 is made of resin or the like.

[0083] Next, power transfer will be described. FIG. 17 is a perspective view showing a frame format of power transfer being performed between the power receiving portion 200 and the power transmitting portion 300. For the sake of simplifying the drawing, when power transfer is performed, the power receiving portion 200 and the power transmitting portion 300 are arranged opposing one another across an air gap, as shown in FIG. 17. The coil unit 24 of the power receiving portion 200 and the coil unit 64 of the power transmitting portion 300 each form a solenoid coil unit.

[0084] When power transfer is performed between the power receiving portion 200 and the power transmitting portion 300, the coil unit 24 of the power receiving portion 200 and the coil unit 64 of the power transmitting portion 300 are arranged opposing one another, and alternating current of a predetermined frequency is supplied to the power transmitting coil 62 of the power transmitting portion 300. An electromagnetic field that oscillates at the predetermined frequency forms around the power transmitting coil 62. Magnetic flux formed in this electromagnetic field has a so-called arched shape. The power receiving coil 22 of the power receiving portion 200 receives power from this electromagnetic field.

[0085] FIG 18 is a sectional view showing power transfer being performed between the power receiving portion 200 and the power transmitting portion 300. When power transfer is performed, the magnetic flux formed in the electromagnetic field includes a magnetic flux DR11 that is supplied directly to power transfer, as well as magnetic fluxes DR21, DR22, DR31, and DR32 (leakage fluxes) that are not supplied directly to power transfer.

[0086] Typically, the power transfer efficiency tends to decrease when the power receiving portion and the power transmitting portion are relatively mismatched (i.e., offset from one another) when transmitting and receiving power. Typically, the leakage flux that is not supplied directly to power transfer tends to become large when the power receiving portion and the power transmitting portion have structures capable of inhibiting a decrease in the power transfer efficiency even if there is a mismatch (i.e., offset).

[0087] In this example embodiment, the magnetic members 220 and 320 are characteristic in that they are easily magnetized, so a so-called bypass magnetic path is formed, which enables the magnetic fluxes DR21, DR22, DR31 , and DR32 that attempt to extend peripherally as leakage fluxes to be reduced. Therefore, the power receiver 11 that includes the power receiving portion 200, the power transmitter 50 that includes the power transmitting portion 30Q, and the power transfer system 1000 that includes the power receiver 1 1 and the power transmitter 50 enable the leakage magnetic field generated at the time of power transfer to be reduced. The power receiver 11 that includes the power receiving portion 200, the power transmitter 50 that includes the power transmitting portion 300, and the power transfer system 1000 that includes the power receiver 11 and the power transmitter 50 also enable high frequency emissions to be reduced.

[0088] The material used for the magnetic members 220 and 320 preferably has low magnetic resistance at the drive frequency used for contactless power transfer (the relative permeability is preferably higher than the value of a ferrite equivalent), and has low loss (i.e., has a loss of equal to or less than the value of a ferrite equivalent). For example, at a drive frequency when power is being transmitted contactlessly, the relative permeability of the magnetic members 220 and 320 is preferably larger than 100. A core loss of the magnetic members 220 and 320 is preferably less than 10,000 kW/m³.

[0089] Referring to FIG. 19, typically a leakage magnetic field that is generated in regions R22 and R24 positioned in the direction in which the winding axis 01 extends when viewed from the coil unit 64 is larger than a leakage magnetic field that is generated in regions R23 and R25 positioned in the direction orthogonal to the winding axis 01 when viewed from the coil unit 64. The permeability of the side wall portions 322 and 324 positioned on the side with the regions R22 and R24, respectively, when viewed from the power transmitting coil 62 may be higher than the permeability of the side wall portions 323 and 325 positioned on the side with the regions R23 and R25, respectively, when viewed from the power transmitting coil 62. The magnetic member 320 may be configured to include the side wall portions 322 and 324, but not include the side wall portions 323 and 325. The magnetic member 320 may be configured to include one of the side wall portion 322 and the side wall portion 324, but not include the side wall portions 323 and 325.

[0090] This is also the same for the magnetic member 220 used on the power receiving portion 200 side. The permeability of the side wall portions 222 and 224 positioned on the sides where the winding axis 02 extends when viewed from the power receiving coil 22 may be higher than the permeability of the side wall portions 223 and 225. The magnetic member 220 may be configured to include the side wall portions 222 and 224, but not include the side wall portions 223 and 225. The magnetic member 220 may also be configured to include one of the side wall portion 222 and the side wall portion 224, but not include the side wall portions 223 and 225.

[0091] The ability of the power receiver 1 1 of this example embodiment to reduce leakage magnetic field is not limited to when power transfer is performed between it and the power transmitter 50 of this example embodiment. That is, the power receiver 11 of this example embodiment is also able to reduce leakage magnetic field when power transfer is performed between it and another power transmitter. Also, the ability of the power transmitter 50 of this example embodiment to reduce leakage magnetic field is not limited to when power transfer is performed between it and the power receiver 11 of this example embodiment. That is, the power transmitter 50 of this example embodiment is also able to reduce leakage magnetic field when power transfer is performed between it and another power receiver.

[0092] Next, a first modified example of the first example embodiment will be described. FIG 20 is a plan view of a power receiving portion 200A according to the first modified example of the first example embodiment. FIG. 21 is a sectional view taken along line XXI - XXI in FIG. 20. FIG. 22 is a perspective view of the power receiving portion 200A in a disassembled state. The power receiving portion 200A differs from the power receiving portion 200 in the first example embodiment in that it is provided with a magnetic member 220A.

[0093] As shown in FIGS. 20 to 22, the magnetic member 220 A has a back surface portion 221 , but does not have a side wall portion of the magnetic member 220 (first example embodiment). The other structure of the magnetic member 220A is the same as that of the magnetic member 220.

[0094] FIG. 23 is a plan view of a power transmitting portion 300A according to the first modified example of the first example embodiment. FIG 24 is a sectional view taken along line XXIV - XXIV in FIG. 23. FIG. 25 is a perspective view of the power transmitting portion 300A in a disassembled state. The power transmitting portion 300A differs from the power transmitting portion 300 in the first example embodiment in that it is provided with a magnetic member 320A.

[0095] As shown in FIGS. 23 to 25, the magnetic member 320A has a back surface portion 321, but does not have a side wall portion of the magnetic member 320 (first example embodiment). The other structure of the magnetic member 320A is the same as that of the magnetic member 320.

[0096] In this modified example as well, the back surface portion 221 of the magnetic member 220A and the back surface portion 321 of the magnetic member 320A are characteristic in that they are easily magnetized when power transfer is performed, so a so-called bypass magnetic path is formed, which enables magnetic flux that attempts to extend peripherally as leakage flux to be reduced. Therefore, a power receiver that includes the power receiving portion 200A, a power transmitter that includes the power transmitting portion 300 A, and a power transfer system that includes the power receiver and the power transmitter also enable the leakage magnetic field generated at the time of power transfer to be reduced.

[0097] The ability of the power receiver of this modified example to reduce leakage magnetic field is not limited to when power transfer is performed between it and the power transmitter of this modified example. That is, the power receiver of this modified example is also able to reduce leakage magnetic field when power transfer is performed between it and another power transmitter. Also, the ability of the power transmitter of this modified example to reduce leakage magnetic field is not limited to when power transfer is performed between it and the power receiver of this modified example. That is, the power transmitter of this modified example is also able to reduce leakage magnetic field when power transfer is performed between it and another power receiver.

[0098] Next, a second modified example of the first example embodiment will be described. FIG. 26 is a perspective view of a power receiving portion 200B according to the second modified example of the first example embodiment. FIG. 27 is a sectional view taken along line XXVII - XXVII in FIG 26. FIG. 28 is a sectional view taken along line XXVIII - XXVIII in FIG. 26. FIG. 29 is a perspective view of the power receiving portion 200B in a disassembled state. The power receiving portion 200B differs from the power receiving portion 200 in the first example embodiment in that it is provided with a magnetic member 220B.

[0099] As shown in FIGS. 26 to 29, the magnetic member 220B has side wall portions 222 to 225, but does not have a back surface portion of the magnetic member 220 (first example embodiment). The other structure of the magnetic member 220B is the same as that of the magnetic member 220.

[0100] FIG. 30 is a perspective view of a power transmitting portion 300B according to the second modified example of the first example embodiment. FIG. 31 is a sectional view taken along line XXXI - XXXI in FIG. 30. FIG 32 is a sectional view taken along line XXXII - XXXII in FIG 30. FIG. 33 is a perspective view of the power transmitting portion 300B in a disassembled state. The power transmitting portion 300B differs from the power transmitting portion 300 in the first example embodiment in that it is provided with a magnetic member 320B.

[0101] As shown in FIGS. 30 to 33, the magnetic member 320B has side wall pun ions 322 to 325, but does not have a back surface portion of the magnetic member 320 (first example embodiment). The other structure of the magnetic member 320B is the same as that of the magnetic member 320. [0102] In this modified example as well, the side wall portions 222 to 225 of the magnetic member 220B and the side wall portions 322 to 325 of the magnetic member 320B are characteristic in that they are easily magnetized when power transfer is performed, so magnetic flux that attempts to extend peripherally as leakage flux is able to be reduced. Therefore, a power receiver that includes the power receiving portion 200B, a power transmitter that includes the power transmitting portion 300B, and a power transfer system that includes the power receiver and the power transmitter also enable the leakage magnetic field generated at the time of power transfer to be reduced.

[0103] The ability of the power receiver of this modified example to reduce leakage magnetic field is not limited to when power transfer is performed between it and the power transmitter of this modified example. That is, the power receiver of this modified example is also able to reduce leakage magnetic field when power transfer is performed between it and another power transmitter. Also, the ability of the power transmitter of this modified example to reduce leakage magnetic field is not limited to when power transfer is performed between it and the power receiver of this modified example. That is, the power transmitter of this modified example is also able to reduce leakage magnetic field when power transfer is performed between it and another power receiver.

[0104] Next, a third modified example of the first example embodiment will be described. FIG. 34 is a perspective view of a magnetic member 220C and an electromagnetic shield 210 used in a power receiving portion according to the third modified example of the first example embodiment. FIG. 35 is a plan view of a power receiving portion 200C according to the third modified example of the first example embodiment. The power receiving portion 200C differs from the power receiving portion 200 in the first example embodiment in that it is provided with the magnetic member 220C.

[0105] As shown in FIGS. 34 and 35, the back surface portion 221 of the magnetic member 220C has an opening 226. The other structure of the magnetic member 220C is the same as that of the magnetic member 220. The opening 226 has an area (i.e., an open area) that is smaller than the area of the electromagnetic shield 210 when the electromagnetic shield 210 is viewed from above in the first direction DRl. An inner peripheral edge of the back surface portion 221 that forms the opening 226 (i.e., the outer shape of the opening 226) has a rectangular shape. The inner peripheral edge of the back surface portion 221 is positioned to the outside of the outer edge of the coil unit 24 (i.e., the ferrite core 21 and the power receiving coil 22).

[0106] As with a magnetic member 220C1 shown in FIG. 36, the inner peripheral edge of the back surface portion 221 that forms the opening 226 (i.e., the outer shape of the opening 226) may also be formed so as to intersect (or overlap with) the outer edge of the coil unit 24 (i.e., the ferrite core 21 and the power receiving coil 22). When the coil unit 24 is housed in the case body 270 (see FIG 10), the inner peripheral edge of the back surface portion 221 that forms the opening 226 (i.e., the outer shape of the opening 226) may be formed so as to intersect (or overlap with) the outer edge of the top plate portion 251 (see FIG. 10) of the shield portion 250.

[0107] As with a magnetic member 220C2 shown in FIG. 37, the inner peripheral edge of the back surface portion 221 that forms the opening 226 (i.e., the outer shape of the opening 226) may also be formed positioned to the inside of the outer edge of the coil unit 24 (i.e., the ferrite core 21 and the power receiving coil 22). When the coil unit 24 is housed in the case body 270 (see FIG 10), the inner peripheral edge of the back surface portion 221 that forms the opening 226 (i.e., the outer shape of the opening 226) may be formed positioned to the inside of the outer edge of the top plate portion 251 (see FIG 10) of the shield portion 250.

[0108] The area of the opening 226 when the opening 226 is viewed from above in the first direction DRl may be larger than the area of the electromagnetic shield 210 when the electromagnetic shield 210 is viewed from above in the first direction DRl . The inner peripheral edge of the back surface portion 221 that forms the opening 226 (i.e., the outer shape of the opening 226) may be positioned to the outside of the outer shape of the electromagnetic shield 210.

[0109] According to the power receiving portion provided with the magnetic member 220C (FIGS. 34 and 35), the magnetic member 220C1 (FIG 36), or the magnetic member 220C2 (FIG. 37), the weight of the power receiving portion 200 is able to be reduced. The power receiving portion 200 is also able to be made smaller by using the space inside the opening 226 to arrange other devices therein. A structure having the kind of opening 226 in this modified example may also be used with the magnetic member of the power transmitting portion.

[0110] The ability of the power receiver of this modified example to reduce leakage magnetic field is not limited to when power transfer is performed between it and the power transmitter of this modified example. That is, the power receiver of this modified example is also able to reduce leakage magnetic field when power transfer is performed between it and another power transmitter. Also, the ability of the power transmitter of this modified example to reduce leakage magnetic field is not limited to when power transfer is performed between it and the power receiver of this modified example. That is, the power transmitter of this modified example is also able to reduce leakage magnetic field when power transfer is performed between it and another power receiver.

[0111] Here, a test example 1 of the first example embodiment will be described. The test example 1 for a test performed related to the first example embodiment described above will now be described with reference to FIGS. 38 to 41. In this test example, a power transmitting portion 300V shown in FIG 38 and a power transmitting portion 450C shown in FIG. 39 were prepared as comparative examples. The power transmitting portion 300V is the same as the power transmitting portion 300 (see FIG. 14) in the first example embodiment described above, minus the magnetic member 320.

[0112] The power transmitting portion 450C is a so-called circular coil unit. The power transmitting portion 450C includes an electromagnetic shield 410 and a coil unit 464. The electromagnetic shield 410 has an annular shape. The coil unit 464 includes a ferrite core 461 and a power transmitting coil 462. The ferrite core 461 is mounted on the electromagnetic shield 410 (i.e., on the side opposite the power receiver when viewed from the electromagnetic shield 410). The power transmitting coil 462 has a shape wound in a spiral shape, and is arranged on the ferrite core 461 (i.e., on the side opposite the power receiver when viewed from the ferrite core 461 ).

[0113] FIG. 40 is a graph indicating values of magnetic flux density at positions away from a coil unit. Line LN1 (the line on which the black circles are plotted) shows the results when power transfer is performed between the power transmitting portion 300V (FIG. 38) and a power receiving portion having no magnetic member. The power receiving portion having no magnetic member is the same as the power receiving portion 200 (see FIG. 8) of the first example embodiment described above, minus the magnetic member 220. With the line LN1 , the position (on the horizontal axis) in FIG. 40 indicates a value of a position away from the coil unit in the winding axis direction. The line LN1 indicates an actual measured value, and the chain double-dashed line LS I adjacent to the line LN1 shows the results for the structure (i.e., the structure relating to line LN1 ) according to simulation software. Electromagnetic field analysis software (JMAG R egistered trademark) by JSOL Corporation) was used for the simulation software.

[0114] Line LN2 (the line on which the black squares are plotted) shows the results when power transfer is performed between the power transmitting portion 300 (see FIG. 14) having the magnetic member 320 (ferrite) on the side opposite the coil unit 64 of the electromagnetic shield 310, and a power receiving portion having no magnetic member. The power receiving portion having no magnetic member is the same as the power receiving portion 200 (see FIG. 8) in the first example embodiment described above, minus the magnetic member 220. With the line LN2, the position (on the horizontal axis) in FIG. 40 indicates a value of a position away from the coil unit in the winding axis direction. The line LN2 indicates an actual measured value, and the alternate long and short dash line LS2 adjacent to the line LN2 shows the results for the structure (i.e., the structure relating to line LN2) according to simulation software. The same software as that described above was used for the simulation software.

[0115] Line LN3 (the line on which the black triangles are plotted) shows the results when power transfer is performed between the power transmitting portion 450C (see FIG. 39), and a power receiving portion having the same shape as the power transmitting portion 450C. The power transmitting portion 450C and the power receiving portion relating to this structure (the structure relating to the line LN3) are not provided with a magnetic member that corresponds to the magnetic member 320 (ferrite) of the example embodiment described above. The line LN3 indicates an actual measured value, and the broken line LS3 adjacent to the line LN 3 shows the results for the structure (i.e., the structure relating to line LN3) according to simulation software. The same software as that described above was used for the simulation software.

[0116] As shown in FIG. 40, the line LN2 according to the example embodiment described above is positioned lower than the line LN1 that serves as the comparative example. It is therefore evident that using the magnetic member 320 enables the leakage magnetic field to be reduced in a solenoid coil unit as well, so the leakage magnetic field is able to approximate the leakage magnetic field generated when power transfer is performed between circular coil units.

[0117] Referring to FIG. 41 , line LS4 as another simulation result shows the results when power transfer is performed between the power transmitting portion 300 (see FIG. 14) having the magnetic member 320 (ferrite) on the opposite side of the electromagnetic shield 3 10 from the coil unit 64, and die power receiving portion 200 (FIG. 8) that has the magnetic member 220 (ferrite) on the opposite side of the electromagnetic shield 210 from the coil unit 24. The same software as that described above was used for the simulation software. The position (on the horizontal axis) in FIG. 41 indicates a value of a position away from the coil unit in the winding axis direction.

[0118] Referring to FIG 41, the results of the simulation indicated by the line LS4, as well as the simulations indicated by the lines LSI , LS2, and LS3 in FIG. 40 were obtained. The lines LSI, LS2, and LS3 in FIG. 41 correspond to the lines LSI, LS2, and LS3 in FIG. 40. The line SL4 relates to the first example embodiment described above, in which the magnetic member 220 is provided in the power receiving portion 200, and the magnetic member 320 is provided in the power transmitting portion 300. The line LS4 is positioned even lower than the line LS2. From the results of the simulation, it is evident that leakage magnetic field is able to be further reduced in a solenoid coil unit by using the magnetic member 220 and the magnetic member 320.

[0119] Next, a test example 2 of the first example embodiment will be described. The test example 2 for a test performed related to the first example embodiment described above will be described with reference to FIGS. 42 to 45. In this test example, a power transmitting portion 300D shown in FIG. 42 was prepared. The power transmitting portion 300D has a so-called solenoid coil unit. FIG, 43 is a perspective view taken along line XLIII - XLIII in FIG. 42.

[0120] As shown in FIGS. 42 and 43, the power transmitting portion 300D includes the coil unit 64, the shield portion 350, the electromagnetic shield 310, and the magnetic member 320D. The coil unit 64 includes the ferrite core 61 , the power transmitting coil 62, and fixed members 331 and 332. The ferrite core 61 is sandwiched between the fixed members 331 and 332 that have plate shapes. The power transmitting coil 62 is wound around the fixed members 331 and 332.

[0121] The shield portion 350 has the bottom plate portion 351 and the peripheral wall portions 352 to 355. The electromagnetic shield 310 is arranged between the bottom plate portion 351 of the shield portion 350 and the coil unit 64. The coil unit 64, the electromagnetic shield 310, and the shield portion 350 are integrated using fastening members 391. The magnetic member 320D has a flat plate shape. The magnetic member 320D is positioned on the opposite side from the coil unit 64 when viewed from the electromagnetic shield 310, and is configured as a back surface portion.

[0122] FIG. 44 is a graph indicating values of magnetic flux density at positions away from the coil unit. FIG. 44 shows the results based on the power transmitting portion 300D (FIGS. 42 and 43), and the results based on a power transmitting portion having the same structure as the power transmitting portion 300D, minus the magnetic member 320. FIG 44 shows the results according to simulation software. Electromagnetic field analysis software (JMAG (registered trademark) by JSOL Corporation) was used for the simulation software.

[0123] As shown in FIG. 44, it is evident that even with a solenoid coil unit, leakage magnetic field is able to be reduced at positions 1 m, 3 m, 10 m, and 30 m from the coil unit 64 by using the magnetic member 320D.

[0124] FIG. 45 is a view of a Total value of field intensity of the power transmitting portion 300D (FIGS. 42 and 43), and a Total value of field intensity of a power transmitting portion having the same structure as the power transmitting portion 300D, minus the magnetic member 320D. FIG. 45 shows the results according to simulation software. The same software as that used to obtain the results shown in FIG. 44 was used for the simulation software. As shown in FIG. 45, it is evident that even with a solenoid coil unit, leakage magnetic field intensity is able to be reduced by using the magnetic member 320D.

[0125] Next, a test example 3 of the first example embodiment will be described.

The test example 3 for a test performed related to the first example embodiment described above will be described with reference to FIGS. 46 to 48. In this test example, a power transmitting portion shown in FIG. 46 was prepared. This power transmitting portion includes an electromagnetic shield 310 and a magnetic member 320 W. An opening 326 having a square shape is provided in the center of a back surface portion 321 of the magnetic member 320 W. The electromagnetic shield 310 has a size of 450 mm x 450 mm x 1 mm. The electromagnetic shield 310 is arranged between the coil unit 64 and the back surface portion 321 of the magnetic member 320 W.

[0126] A size LL10 ^χ LL20 of the magnetic member 320W is 490 mm x 510 mm, and a thickness thereof is 5 mm. Three of these magnetic members 320W, each with a different value for the size of the LL1 x LL2 of the opening 326, were prepared. In FIG. 46, the coil unit 64 is shown using a dotted line for the sake of convenience. In FIG 46, the region indicated by diagonal hatching corresponds to the back surface portion 321, and the region to the inside of the diagonal hatching corresponds to the opening 326.

[0127] One magnetic member 320W was prepared with the size LL1 x LL2 of the opening 326 being 160 mm x 100 mm. The area of the back surface portion 321 of the magnetic member 320 having the opening 326 of this size is 6.4% smaller than the area of the back surface portion 321 without the opening 326.

[0128] Another magnetic member 320W was prepared with the size LL1 x LL2 of the opening 326 being 320 mm ^χ 300 mm. The area of the back surface portion 321 of the magnetic member 320 having the opening 326 of this size is 38% smaller than the area of the back surface portion 321 without the opening 326.

[0129] Still another magnetic member 320W was prepared with the size LL1 x LL2 of the opening 326 being 400 mm x 400 mm. The area of the back surface portion

321 of the magnetic member 320 having the opening 326 of this size is 64% smaller than the area of the back surface portion 321 without the opening 326.

[0130] FIG. 47 is a graph indicating the magnetic flux density at positions away from the coil unit in the X direction in FIG. 46. The X direction referred to here is a direction in which the winding axis OI of the coil unit 64 extends. FIG 48 is a graph indicating the magnetic flux density at positions away from the coil unit in the Y direction in FIG. 46. The Y direction referred to here is a direction orthogonal to the direction in which the winding axis 01 extends (i.e., the X direction) and a vertical direction. FIGS.

47 and 48 both show the results according to simulation software. Electromagnetic field analysis software (JMAG (registered trademark) by JSOL Corporation) was used for the simulation software.

[0131] The conditions of the simulation are a drive frequency of 50 kHz, a gap between coils of 150 mm, and the power for transmitting and receiving power being 3 kW.

[0132] Line LL101 in FIGS. 47 and 48 indicates the results based on a power transmitting portion that is not provided with the magnetic member 320 W. Line LL102 in FIGS. 47 and 48 indicates the results based on a power transmitting portion that is provided with the magnetic member 320 (one without the opening 326).

[0133] Line LL103 in FIGS. 47 and 48 indicates the results based on a power transmitting portion provided with the magnetic member 320W having the opening 326 of 160 mm x 100 mm. Line LL104 in FIGS. 47 and 48 indicates the results based on a power transmitting portion provided with the magnetic member 320W having the opening 326 of 320 mm x 300 mm. Line LL 105 in FIGS. 47 and 48 indicates the results based on a power transmitting portion provided with the magnetic member 320W having the opening 326 of 400 mm x 400 mm. [0134] Referring to FIG. 47, with the power transmitting portion that is not provided with the magnetic member 320 W (line LL 101), a magnetic field in which the magnetic flux density becomes 9.8 μΤ forms at a spot 1 m away in the X direction. With the power transmitting portion that is provided with the magnetic member 320 (one without the opening 326) (line LL102), a magnetic field in which the magnetic flux density becomes 6.02 μΤ forms at a spot 1 m away in the X direction.

[0135] With the power transmitting portion that is provided with the magnetic member 320W having the opening 326 of 160 mm x 100 mm (line LL103), a magnetic field in which the magnetic flux density becomes 6.03 μΤ forms at a spot 1 m away in the X direction. With the power transmitting portion that is provided with the magnetic member 320W having the opening 326 of 320 mm x 300 mm (line LL104), a magnetic field in which the magnetic flux density becomes 6.09 μΤ forms at a spot 1 m away in the X direction. With the power transmitting portion that is provided with the magnetic member 320W having the opening 326 of 400 mm x 400 mm (line LL105), a magnetic field in which the magnetic flux density becomes 6.09 μΤ forms at a spot 1 m away in the X direction.

[0136] The reduction rate of the magnetic flux density at a spot 1 m away in the X direction is reduced approximately 38% from line LL101 for all of lines LL102 to LL105. When comparing the magnetic member 320 that has no opening to a magnetic member that has the opening 326, it is evident that there is almost no visible difference in reduction rates of the magnetic flux density between these.

[0137] Next, a second example embodiment of the invention will be described. FIG 49 is a perspective view of a power receiving portion 200J according to the second example embodiment. FIG 50 is a sectional view taken along line L - L in FIG. 49. FIG 51 is a perspective view of the power receiving portion 200J in a disassembled state. In the power receiving portion 200J, the positional relationship between the back surface portion 221 of the magnetic member 220 and the electromagnetic shield 210 is reversed from what it is in the power receiving portion 200 of the first example embodiment.

[0138] More specifically, the electromagnetic shield 210 has a flat plate shape (see FIG 51). An aluminum plate having a thickness of 1 mm, for example, may be used as the electromagnetic shield 210. The electromagnetic shield 210 is arranged on the opposite side from the side on which the power receiving coil 22 is positioned when viewed from the back surface portion 221 of the magnetic member 220. The electromagnetic shield 210 is arranged extending in the second direction DR2. In this example embodiment, the shield portion 250 is also arranged between the magnetic member 220 and the coil unit 24.

[0139] When the electromagnetic shield 210 and the back surface portion 221 and the magnetic member 220 are viewed from above in the first direction DR1, the outer edge of the back surface portion 221 is positioned to the inside of the outer edge of the electromagnetic shield 210 (see FIGS. 49 and 50). The area of the electromagnetic shield 210 when the electromagnetic shield 210 is viewed from above in the first direction DR1 is larger than the area of the back surface portion 221 when the back surface portion 221 is viewed from above in the first direction DRl .

[0140] Next, a power transmitting portion 300J will be described. FIG. 52 is a perspective view of the power transmitting portion 300J according to the second example embodiment. FIG. 53 is a sectional view taken along line LIII - LIII in FIG. 52. FIG 54 is a perspective view of the power transmitting portion 300J in a disassembled state. In the power transmitting portion 300J, the positional relationship between the back surface portion 321 of the magnetic member 320 and the electromagnetic shield 310 is reversed from what it is in the power transmitting portion 300 of the first example embodiment.

[0141] More specifically, the electromagnetic shield 310 has a flat plate shape (see FIG 54). An aluminum plate having a thickness of 1 mm, for example, may be used as the electromagnetic shield 310. The electromagnetic shield 310 is arranged on the opposite side from the side on which the power transmitting coil 62 is positioned when viewed from the back surface portion 321 of the magnetic member 320J. The electromagnetic shield 310 is arranged extending in the second direction DR2. In this example embodiment, the shield portion 350 is also arranged between the magnetic member 320J and the coil unit 64. [0142] When the electromagnetic shield 310 and the back surface portion 321 and the magnetic member 320 are viewed from above in the first direction DR1, the outer edge of the back surface portion 321 is positioned to the inside of the outer edge of the electromagnetic shield 310 (see FIGS. 52 and 53). The area of the electromagnetic shield 310 when the electromagnetic shield 310 is viewed from above in the first direction DR1 is larger than the area of the back surface portion 321 when the back surface portion 321 is viewed from above in the first direction DR1.

[0143] FIG. 55 is a sectional view illustrating the manner in which power transfer is performed between the power receiving portion 200J and the power transmitting portion 300J. When power transfer is performed, the magnetic flux formed in the electromagnetic field includes a magnetic flux DR1 1 that is supplied directly to power transfer, as well as magnetic fluxes DR21, DR22, DR31, and DR32 (leakage fluxes) that are not supplied directly to power transfer.

[0144] Typically, the power transfer efficiency tends to decrease when the power receiving portion and the power transmitting portion are relatively mismatched (i.e., offset from one another) when transmitting and receiving power. Typically, the leakage flux that is not supplied directly to power transfer tends to become large when the power receiving portion and the power transmitting portion have structures capable of inhibiting a decrease in the power transfer efficiency even if there is a mismatch (i.e., offset).

[0145] In this example embodiment, the magnetic members 220 and 320 are characteristic in that they are easily magnetized, so the magnetic fluxes DR21 , DR22, DR31 , and DR32 that attempt to extend peripherally as leakage fluxes are able to be reduced. Therefore, the power receiver that includes the power receiving portion 200J, the power transmitter that includes the power transmitting portion 300J, and the power transfer system that includes the power receiver and the power transmitter enable the leakage magnetic field generated at the time of power transfer to be reduced. The power receiver that includes the power receiving portion 200J, the power transmitter that includes the power transmitting portion 300J, and the power transfer system that includes the power receiver and the power transmitter also enable high frequency emissions to be reduced. [0146] The material used for the magnetic members 220 and 320 preferably has low magnetic resistance at the drive frequency used for contactless power transfer (the relative permeability is preferably higher than the value of a ferrite equivalent), and has low loss (i.e., has a loss of equal to or less than the value of a ferrite equivalent). For example, at a drive frequency when power is being transmitted contactlessly, the relative permeability of the magnetic members 220 and 320 is preferably larger than 100. A core loss of the magnetic members 220 and 320 is preferably less than 10,000 kW/ml

[0147] With the magnetic member 320J of the power transmitting portion 300J, the permeability of the side wall portions 322 and 324 may be higher than the permeability of the side wall portions 323 and 325. The magnetic member 320J may also be configured to include the side wall portions 322 and 324, but not include the side wall portions 323 and 325. The magnetic member 320J may also be configured to include one of the side wall portion 322 and the side wall portion 324, but not include the side wall portions 323 and 325.

[0148] This is also the same for the magnetic member 220 used on the power receiving portion 200J side. The permeability of the side wall portions 222 and 224 may be higher than the permeability of the side wall portions 223 and 225. The magnetic member 220 may be configured to include the side wall portions 222 and 224, but not include the side wall portions 223 and 225. The magnetic member 220 may also be configured to include one of the side wall portion 222 and the side wall portion 224, but not include the side wall portions 223 and 225.

[0149] The ability of the power receiver of this example embodiment to reduce leakage magnetic field is not limited to when power transfer is performed between it and the power transmitter of this example embodiment. That is, the power receiver of this example embodiment is also able to reduce leakage magnetic field when power transfer is performed between it and another power transmitter. Also, the ability of the power transmitter of this example embodiment to reduce leakage magnetic field is not limited to when power transfer is performed between it and the power receiver of this example embodiment. That is, the power transmitter of this example embodiment is also able to reduce leakage magnetic field when power transfer is performed between it and another power receiver.

[0150] FIG. 56 is a view of the results after measuring, by simulation, the intensity distribution of leakage magnetic field around the power transmitting portion according to the second example embodiment, Of the regions indicated by the diagonal lines in FIG 56, those in which the diagonal lines are closer together indicate a greater magnetic field intensity than those in which the diagonal lines are not close together. It is evident that the leakage magnetic field is reduced by the presence of the side wall portion 322, in particular, of the magnetic member 320. It is thought that the leakage magnetic field flows to the side wall portion 322 and the back surface portion 321, as indicated by the black arrows in the drawing.

[0151] FIG. 57 is a view of the results after measuring, by simulation, the intensity distribution of leakage magnetic field around a power transmitting portion that is not provided with a magnetic member corresponding to the magnetic member 320, as a comparative example of FIG. 56. Of the regions indicated by the diagonal lines in FIG 57, those in which the diagonal lines are closer together indicate a greater magnetic field intensity than those in which the diagonal lines are not close together. It is evident that the leakage magnetic field spreads out in the direction of the winding axis 01. From FIGS. 56 and 57, it is evident that the leakage magnetic field generated at the time of power transfer is able to be further reduced by using the magnetic member 320 in addition to the electromagnetic shield 310 and the shield portion 350.

[0152] Next, a first modified example of the second example embodiment will be described. FIG. 58 is a perspective view of a power receiving portion 200K according to the first modified example of the second example embodiment. FIG. 59 is a sectional view taken along line LIX - LIX in FIG 58. The power receiving portion 200K differs from the power receiving portion 200J of the second example embodiment in that it is provided with a magnetic member 220K.

[0153] As shown in FIGS. 58 and 59, the magnetic member 220K has a back surface portion 221, but does not have a side wall portion of the magnetic member 220J (the second example embodiment). The other structure of the magnetic member 220K is the same as that of the magnetic member 220 J.

[0154] FIG. 60 is a perspective view of a power transmitting portion 300K according to the first modified example of the second example embodiment. FIG. 61 is a sectional view taken along line LXI - LXI in FIG. 60. The power transmitting portion 300K differs from the power transmitting portion 300J of the second example embodiment in that it is provided with a magnetic member 320IC.

[0155] As shown in FIGS. 60 and 61, the magnetic member 320K has a back surface portion 321 , but does not have a side wall portion of the magnetic member 320J (the first example embodiment). The other structure of the magnetic member 32 OK is the same as that of the magnetic member 320J.

[0156] In this modified example as well, the back surface portion 221 of the magnetic member 220K and the back surface portion 321 of the magnetic member 320K are characteristic in that they are easily magnetized when power transfer is performed, so magnetic flux that attempts to extend peripherally as leakage flux is able to be reduced. Therefore, a power receiver that includes the power receiving portion 200K, a power transmitter that includes the power transmitting portion 300K, and a power transfer system that includes the power receiver and the power transmitter also enable the leakage magnetic field generated at the time of power transfer to be reduced.

[0157] The ability of the power receiver of this modified example to reduce leakage magnetic field is not limited to when power transfer is performed between it and the power transmitter of this modified example. That is, the power receiver of this modified example is also able to reduce leakage magnetic field when power transfer is performed between it and another power transmitter. Also, the ability of the power transmitter of this modified example to reduce leakage magnetic field is not limited to when power transfer is performed between it and the power receiver of this modified example. That is, the power transmitter of this modified example is also able to reduce leakage magnetic field when power transfer is performed between it and another power receiver. [0158] Next, a second modified example of the second example embodiment will be described. FIG. 62 is a perspective view of a power receiving portion 200L according to the second modified example of the second example embodiment. FIG 63 is a sectional view taken along line LXIII - LXIII in FIG. 62. The power receiving portion 200L differs from the power receiving portion 200J in the second example embodiment in that it is provided with a magnetic member 220L.

[0159] As shown in FIGS. 62 and 63, the magnetic member 220L has side wall portions 222 to 225, but does not have a back surface portion of the magnetic member 220J (second example embodiment). The other structure of the magnetic member 220K is the same as that of the magnetic member 220J.

[0160] FIG. 64 is a perspective view of a power transmitting portion 300L according to the second modified example of the second example embodiment. FIG. 65 is a sectional view taken along line LXV - LXV in FIG. 64. The power transmitting portion 300L differs from the power transmitting portion 300J in the second example embodiment in that it is provided with a magnetic member 320L.

[0161] As shown in FIGS. 64 to 65, the magnetic member 320L has side wall portions 322 to 325, but does not have a back surface portion of the magnetic member 320J (second example embodiment). The other structure of the magnetic member 320L is the same as that of the magnetic member 320J.

[0162] In this modified example as well, the side wall portions 222 to 225 of the magnetic member 220L and the side wall portions 322 to 325 of the magnetic member 320L are characteristic in that they are easily magnetized when power transfer is performed, so magnetic flux that attempts to extend peripherally as leakage flux is able to be reduced. Therefore, a power receiver that includes the power receiving portion 200L, a power transmitter that includes the power transmitting portion 300L, and a power transfer system that includes the power receiver and the power transmitter also enable the leakage magnetic field generated at the time of power transfer to be reduced.

[0163] The ability of the power receiver of this modified example to reduce leakage magnetic field is not limited to when power transfer is performed between it and the power transmitter of this modified example. That is, the power receiver of this modified example is also able to reduce leakage magnetic field when power transfer is performed between it and another power transmitter. Also, the ability of the power transmitter of this modified example to reduce leakage magnetic field is not limited to when power transfer is performed between it and the power receiver of this modified example. That is, the power transmitter of this modified example is also able to reduce leakage magnetic field when power transfer is performed between it and another power receiver.

[0164] Next, other modified examples of the second example embodiment wil l be described. Just as in the third modified example of the first example embodiment described above, the back surface portions 221 of the magnetic members 220J and 220K may also have an opening 226 (see FIG. 34). The back surface portions 321 of the magnetic member 320J and 320K may also have an opening 326 (see FIG 46).

[0165J The opening 226 in this case may have an area (an open area) that is smaller than the area of the electromagnetic shield 210 when the electromagnetic shield 210 is viewed from above in the first direction DR1. The inner peripheral edge of the back surface portion 221 that forms the opening 226 (i.e., the outer shape of the opening 226) may have a rectangular shape. The inner peripheral edge of the back surface portion 221 may be positioned to the outside of the outer edge of the coil unit 24 (i.e., the ferrite core 21 and the power receiving coil 22).

[0166] The inner peripheral edge of the back surface portion 221 that forms the opening 226 (i.e., the outer shape of the opening 226) may also be formed so as to intersect (or overlap with) the outer edge of the coil unit 24 (i.e., the ferrite core 21 and the power receiving coil 22). When the coil unit 24 is housed inside the case body 270 (see FIG. 10), the inner peripheral edge of the back surface portion 221 that forms the opening 226 (i.e., the outer shape of the opening 226) may also be formed so as to intersect (or overlap with) the outer edge of the top plate portion 251 of the shield portion 250 (see FIG 10).

[0167] The inner peripheral edge of the back surface portion 221 that forms the opening 226 (i.e., the outer shape of the opening 226) may also be formed so as to be positioned to the inside of the outer edge of the coil unit 24 (i.e., the ferrite core 21 and the power receiving coil 22). When the coil unit 24 is housed inside the case body 270 (see FIG. 10), the inner peripheral edge of the back surface portion 221 that forms the opening 226 (i.e., the outer shape of the opening 226) may also be formed so as to be positioned to the inside of the outer edge of the top plate portion 251 of the shield portion 250 (see FIG 10).

[0168] The area of the opening 226 when the opening 226 is viewed from above in the first direction DR1 may be larger than the area of the electromagnetic shield 210 when the electromagnetic shield 210 is viewed from above in the first direction DR1. The inner peripheral edge of the back surface portion 221 that forms the opening 226 (i.e., the outer shape of the opening 226) may also be positioned to the outside of the outer shape of the electromagnetic shield 210. A structure in which the opening 226 is provided, as it is in this modified example, may also be employed with the magnetic member of the power transmitting portion.

[0169] The ability of the power receiver of this modified example to reduce leakage magnetic field is not limited to when power transfer is performed between it and the power transmitter of this modified example. That is,_^the power receiver of this modified example is also able to reduce leakage magnetic field when power transfer is performed between it and another power transmitter. Also, the ability of the power transmitter of this modified example to reduce leakage magnetic field is not limited to when power transfer is performed between it and the power receiver of this modified example. That is, the power transmitter of this modified example is also able to reduce leakage magnetic field when power transfer is performed between it and another power receiver.

Claims

CLAIMS:

1. A power transmitter comprising:

a power transmitting coil (62) that transmits power contactlessly to a power receiving coil (22) in a state opposing the power receiving coil (22), the power transmitting coil (62) being provided surrounding a winding axis that extends in a second direction that intersects a first direction, the first direction being a direction opposing the power receiving coil (22); and

a magnetic member (320, 320A, 320B, 320J, 320K, 320L, 320W) that is arranged in at least one of i) a position on an opposite side from a side that opposes the power receiving coil (22) when viewed from the power transmitting coil (62), and ii) a position to an outside of an outer edge of the power transmitting coil (62) when the power transmitting coil (62) is viewed from above in the first direction.

2. The power transmitter according to claim 1 , wherein

the magnetic member (320, 320A, 320W) includes a back surface portion that is positioned on the opposite side from the side that opposes the power receiving coil (22) when viewed from the power transmitting coil (62), and the magnetic member (320, 320A, 320W) further includes an electromagnetic shield (310) arranged along the second direction between the back surface portion and the power transmitting coil (62).

3. The power transmitter according to claim 2, wherein

an outer edge of the back surface portion is positioned to an outside of an outer edge of the electromagnetic shield (310), when the electromagnetic shield (310) and the back surface portion are viewed from above in the first direction.

4. The power transmitter according to claim 1, wherein

the magnetic member (320J, 320K) includes a back surface portion (321) that is positioned on the opposite side from the side that opposes the power receiving coil (22) when the back surface portion (321) is viewed from the power transmitting coil (62), and the magnetic member (320J, 320K) further includes an electromagnetic shield (310) arranged along the second direction on an opposite side from the side on which the power transmitting coil (62) is positioned when viewed from the back surface portion.

5. The power transmitter according to claim 4, wherein

an outer edge of the back surface portion is positioned to an inside of an outer edge of the electromagnetic shield (310), when the electromagnetic shield (310) and the back surface portion (321 ) are viewed from above in the first direction.

6. The power transmitter according to any one of claims 2 through 5, wherein the back surface portion (321) includes an opening (326) having an area that is smaller than an area of the electromagnetic shield (310) when the electromagnetic shield (310) is viewed from above in the first direction.

7. The power transmitter according to any one of claims 1 through 5, wherein the magnetic member (320, 320A, 320B, 320J, 320K, 320L, 320W) includes a side wall portion (322, 323, 324, 325) that is positioned to an outside of the outer edge of the power transmitting coil (62) when the power transmitting coil (62) is viewed from above in the first direction.

8. The power transmitter according to claim 7, wherein

the side wall portion (322, 323, 324, 325) has a portion that extends so as to intersect the second direction on at least one of one side and the other side in the second direction when the side wall portion (322, 323, 324, 325) is viewed from the power transmitting coil (62).

9. The power transmitter according to any one of claims 1 through 8, wherein at a drive frequency when power is being transmitted contactlessly, a relative permeability of the magnetic member (320, 320A, 320B, 320J, 320K, 320L, 320W) is larger than 100, and a core loss of the magnetic member (320, 320A, 320B, 320J, 320K, 320L, 320W) is less than 10,000 k W/m³.

10. A power receiver comprising:

a power receiving coil (22) that receives power contactlessly from a power transmitting coil (62) in a state opposing the power transmitting coil (62), the power receiving coil (22) being provided surrounding a winding axis that extends in a second direction that intersects a first direction, the first direction being a direction opposing the power transmitting coil (62); and

a magnetic member (220, 220A, 220B, 220C, 220C1 , 220C2, 220J, 220K, 220L) that is arranged in at least one of i) a position on an opposite side from a side that opposes the power transmitting coil (62) when viewed from the power receiving coil (22), and ii) a position to an outside of an outer edge of the power receiving coil (22) when the power receiving coil (22) is viewed from above in the first direction.

11. The power receiver according to claim 10, wherein

the magnetic member (220, 220A, 220C, 220C1 , 220C2) includes a back surface portion that is positioned on the opposite side from the side that opposes the power transmitting coil (62) when viewed from the power receiving coil (22), and the magnetic member (220, 220A, 220C, 220C1, 220C2) further includes an electromagnetic shield (210) arranged along the second direction between the back surface portion and the power receiving coil (22).

12. The power receiver according to claim 11 , wherein

an outer edge of the back surface portion is positioned to an outside of an outer edge of the electromagnetic shield (210), when the electromagnetic shield (210) and the back surface portion (221 ) are viewed from above in the first direction.

13. The power receiver according to claim 10, wherein

the magnetic member (220 J, 220K) includes a back surface portion that is positioned on the opposite side from the side that opposes the power transmitting coil (62) when the back surface portion (321) is viewed from the power receiving coil (22), and the magnetic member (220J, 220K) further includes an electromagnetic shield (210) arranged along the second direction on an opposite side from the side on which the power receiving coil (22) is positioned when viewed from the back surface portion.

14. The power receiver according to claim 13, wherein

an outer edge of the back surface portion (221) is positioned to an inside of an outer edge of the electromagnetic shield (210), when the electromagnetic shield (210) and the back surface portion (221 ) are viewed from above in the first direction.

15. The power receiver according to any one of claims 11 through 14, wherein the back surface portion (221) includes an opening (226) having an area that is smaller than an area of the electromagnetic shield (210) when the electromagnetic shield (210) is viewed from above in the first direction.

16. The power receiver according to any one of claims 10 through 14, wherein the magnetic member (220, 220A, 220B, 220C, 220C1, 220C2, 220J, 220K, 220L) includes a side wall portion (222, 223, 224, 225) that is positioned to an outside of the outer edge of the power receiving coil (22) when the power receiving coil (22) is viewed from above in the first direction.

17. The power receiver according to claim 16, wherein

the side wall portion (222, 223, 224, 225) has a portion that extends so as to intersect the second direction on at least one of one side and the other side in the second direction when the side wall portion (222, 223, 224, 225) is viewed from the power receiving coil (22).

18. The power receiver according to any one of claims 10 through 17, wherein at a drive frequency when power is being received contactlessly, a relative permeability of the magnetic member (220, 220A, 220B, 220C, 220C1 , 220C2, 220J, 220K, 220L) is larger than 100, and a core loss of the magnetic member (220, 220A, 220B, 220C, 220C1, 220C2, 220J, 220K, 220L) is less than 10,000 kW/m³.

19. A power transfer system comprising:

a power receiver (I I) that includes a power receiving coil (22); and

a power transmitter (50) that includes a power transmitting coil (62), the power transmitting coil (62) being provided surrounding a winding axis that extends in a second direction that intersects a first direction, the first direction being a direction opposing the power receiving coil (22), the power transmitter (50) transmitting power contactlessly to the power receiving coil (22) in a state opposing the power receiving coil (22), and the power transmitter (50) further including a magnetic member (320, 320A, 320B, 320J, 320K, 320L, 320W) that is arranged in at least one of i) a position on an opposite side from a side that opposes the power receiving coil (22) when the magnetic member (320, 320A, 320B, 320J, 320K, 320L, 320W) is viewed from the power transmitting coil (62), and ii) a position to an outside of an outer edge of the power transmitting coil (62) when the power transmitting coil (62) is viewed from above in the first direction.

20. A power transfer system comprising:

a power transmitter (50) that includes a power transmitting coil (62); and

a power receiver (11) that includes a power receiving coil (22), the power receiving coil (22) being provided surrounding a winding axis that extends in a second direction that intersects a first direction, the first direction being a direction opposing the power transmitting coil (62), the power receiver (11) receiving power contactlessly from the power transmitting coil (62) in a state opposing the power transmitting coil (62), and the power transmitting coil (62) further including a magnetic member (220, 220A, 220B, 220C, 220C1, 220C2, 220J, 220K, 220L) that is arranged in at least one of i) a position on an opposite side from a side that opposes the power transmitting coil (62) when the magnetic member (220, 220A, 220B, 220C, 220C1, 220C2, 220J, 220K, 220L) is viewed from the power receiving coil (22), and ii) a position to an outside of an outer edge of the power receiving coil (22) when the power receiving coil (22) is viewed from above in the first direction.