WO2011117714A2

WO2011117714A2 - Coil unit, non-contact electric-power receiving apparatus, non-contact electric-power transmitting apparatus, and vehicle

Info

Publication number: WO2011117714A2
Application number: PCT/IB2011/000612
Authority: WO
Inventors: Yukihiro Yamamoto; Taira Kikuchi
Original assignee: Toyota Jidosha Kabushiki Kaisha; Kabushiki Kaisha Toyota Jidoshokki
Priority date: 2010-03-25
Filing date: 2011-03-23
Publication date: 2011-09-29
Also published as: WO2011117714A3; JP2011204836A

Abstract

A coil unit includes: a second self-resonant coil capable of at least one of transmission and reception of electric power to and from a first self-resonant coil via electromagnetic field resonance, the first self-resonant coil being externally provided; a plate (197) that extends in the axial direction of the second self-resonant coil (110) and supports the second self-resonant coil (110); and a bobbin (196) that supports the plates (197).

Description

COIL UNIT, NON-CONTACT ELECTRIC-POWER RECEIVING APPARATUS,

NON-CONTACT ELECTRIC-POWER TRANSMITTING APPARATUS, AND

VEHICLE

BACKGROUND OF THE INVENTION

1. Field of the Invention

[0001] The invention relates to a coil unit, a non-contact electric-power receiving apparatus, a non-contact electric-power transmitting apparatus, and a vehicle, and in particular to a coil unit, a non-contact electric-power receiving apparatus, a non-contact electric-power transmitting apparatus, and a vehicle that are capable of at least one of receiving and transmitting electric power via electromagnetic field resonance.

2. Description of the Related Art

[0002] In recent years, focus is placed on a non-contact charging method, which is a method of charging a battery mounted on a vehicle.

[0003] For example, the electric vehicle described in Japanese Patent Application Publication No. 2009-106136 (JP-A-2009-106136) includes: a secondary self-resonant coil that is magnetically coupled to a primary self-resonant coil outside the vehicle via magnetic field resonance and is configured to be able to receive electric power from the primary self-resonant coil; a secondary coil configured to be able to receive electric power from the secondary self-resonant coil via electromagnetic induction; a rectifier that rectifies the electric power received by the secondary coil; an electricity storage device that stores electric power rectified by the rectifier; and an electric motor that receives electric power from the electricity storage device to generate vehicle driving force.

[0004] JP-A-2009-106136 does not describe the method of fixing the secondary self-resonant coil, the secondary coil, etc. As a method of installing a coil, for example, it is conceivable to employ a method, in which the secondary self-resonant coil and the secondary coil are installed on a bobbin, in which a spiral groove(s) is/are formed. [0005] When the secondary self-resonant coil is fitted to the spiral groove, the contact area between the secondary self-resonant coil and the bobbin is large and when the bobbin is made of a dielectric substance, such as resin, the dielectric loss is large. SUMMARY OF THE INVENTION

[0006] The invention provides a coil unit, a non-contact electric-power receiving apparatus, a non-contact electric-power transmitting apparatus, and a vehicle, in which the dielectric loss is reduced.

[0007] A coil unit according to a first aspect of the invention includes: a second self-resonant coil capable of at least one of transmission and reception of electric power to and from a first self-resonant coil externally provided via electromagnetic field resonance; a plate that extends in the axial direction of the second self-resonant coil and supports the second self-resonant coil; and a support member that supports the plate.

The plate may be provided detachably from the support member.

[0008] A recess that receives the second self-resonant coil may be formed in the plate and the width of the recess may be greater than the diameter of the cross section of the second self-resonant coil.

[0009] The support member may be a bobbin that is disposed inside the second self-resonant coil, and the plate may be provided on an outer circumferential surface of the bobbin. Alternatively, the support member may be a bobbin that is disposed outside the second self-resonant coil, and the plate may be provided on an inner circumferential surface of the bobbin.

[0010] A configuration may be employed, in which: the support member is disposed on each side of the second self-resonant coil in an axial direction of the second self-resonant coil; a plurality of the plates are arranged along the second self-resonant coil so as to extend in the axial direction, each of the plates being connected to the support member on each side of the second self-resonant coil in the axial direction; and the second self-resonant coil has a high rigidity such that the second self-resonant coil can maintain its form independently. [0011] The coil unit may further include an electromagnetic induction coil, wherein the electromagnetic induction coil is capable of at least one of transmitting electric power via electromagnetic induction to the second self-resonant coil that transmits electric power to the first self-resonant coil and receiving electric power via electromagnetic induction from the second self-resonant coil that receives electric power from the first self-resonant coil, and the electromagnetic induction coil is supported by the plate.

[0012] A non-contact electric-power receiving apparatus according to a second aspect of the invention includes the above coil unit, wherein the non-contact electric-power receiving apparatus is capable of charging an electricity storage device.

[0013] A vehicle according to a third aspect of the invention includes the above non-contact electric-power receiving apparatus and the electricity storage device. A non-contact electric-power transmitting apparatus according to a fourth aspect of the invention includes the above coil unit, wherein electric power is supplied from an external power supply.

[0014] With any of the coil unit, the non-contact electric-power receiving apparatus, the non-contact electric-power transmitting apparatus, and the vehicle, it is possible to reduce the dielectric loss. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The foregoing and further objects, features and advantages of the invention will become apparent from the following description of example embodiments with reference to the accompanying drawings, wherein like numerals are used to represent like elements and wherein:

FIG. 1 is an overall configuration diagram of a non-contact power supply system according to an embodiment of the invention;

FIG. 2 is a diagram for explaining the principle of electric power transmission using the resonance method;

FIG. 3 is a diagram showing relations between the distance from the electric current source (magnetic current source) and the intensity of the electromagnetic field;

FIG. 4 is a schematic diagram showing electromagnetic shielding cases 190 and 250 shown in FIG. 1 and the surrounding structure;

FIG. 5 is a perspective view of a coil case 191;

FIG. 6 is an exploded perspective view of the coil case 191 shown in FIG. 5;

FIG. 7 is a perspective view showing part of the circumferential surface of a bobbin

196;

FIG. 8 is a side view of a plate 197;

FIG. 9 is a side view of a plate 197 that is provided at another position than the position of the plate 197 shown in FIG. 8;

FIG. 10 is a front view of the plate 197;

FIG. 11 is a perspective view showing a modification of the plate 197;

FIG. 12 is a perspective view showing a first modification of a coil unit;

FIG. 13 is a side view of the plate 197 attached to the bobbin 196 shown in FIG. 12; FIG. 14 is a perspective view showing a second modification of the coil unit; and

FIG. 15 is a perspective view showing a third modification of the coil unit.

DETAILED DESCRIPTION OF EMBODIMENTS

[0016] FIG. 1 is an overall configuration diagram of a non-contact power supply system according to an embodiment of the invention. Referring to FIG. 1, the non-contact power supply system includes an electric vehicle 100 and a power supply apparatus (non-contact electric-power transmitting apparatus) 200. The electric vehicle

100 includes a non-contact electric-power receiving apparatus 101, a power control unit (hereinafter also referred to as the "PCU") 160, an electric motor 170, and a vehicle electronic control unit (ECU) 145. The non-contact electric-power receiving apparatus .

101 includes a coil unit 180, a rectifier 130, a DC/DC converter 140, an electricity storage device 150, and electrical equipment 400 installed in an electromagnetic shielding case 190.

[0017] The configuration of the electric vehicle 100 is not limited to that shown in FIG. 1 as long as the vehicle is driven by an electric motor. Examples of the vehicle include a hybrid vehicle provided with an electric motor and an internal combustion engine, and a fuel cell vehicle provided with a fuel cell. The coil unit 180 includes a secondary self-resonant coil (second self-resonant coil) 110 and a secondary coil 120, which functions as an electromagnetic induction coil, and the coil unit 180 is accommodated in the electromagnetic shielding case 190.

[0018] The secondary self-resonant coil 110 is provided under a vehicle body, for example. Both ends of the secondary self-resonant coil 110 are free ends and the capacitance of the secondary self-resonant coil 110 is stray capacitance. The secondary self-resonant coil 110 is capable of at least one of receiving electric power from the power supply apparatus 200 and transmitting electric power to the power supply apparatus 200 by resonating with a primary self-resonant coil (first self-resonant coil) 240 (described later) of the power supply apparatus 200 via electromagnetic field. Note that although both ends of the secondary self-resonant coil 110 are free ends, an additional capacitor (not shown) may be connected across both ends of the secondary self-resonant coil 110.

[0019] , The number of turns of the secondary self-resonant coil 110 is appropriately set based on the distance between the secondary self-resoiiant coil 110 and the primary self-resonant coil 240 of the power supply apparatus 200, the resonance frequency of the primary self-resonant coil 240 and the secondary self-resonant coil 110, etc. so that the Q factor (Q > 100, for example) that indicates the intensity of resonance of the primary self-resonant coil 240 and the secondary self-resonant coil 110, kappa that indicates the degree of coupling therebetween, etc. become large.

[0020] The secondary coil 120 is provided coaxially with the secondary self-resonant coil 110 and can be magnetically coupled to the secondary self-resonant coil 110 via electromagnetic induction. The secondary coil 120 is capable of at least one of receiving, via electromagnetic induction, electric power received by the secondary self-resonant coil 110 to output the electric power to the rectifier 130 and supplying, to the secondary self-resonant coil 110, the electric power to be transmitted from the secondary self-resonant coil 110 to the primary self-resonant coil 240.

[0021] The rectifier 130 rectifies the alternating current received by the secondary coil 120. Based on the control signal from the vehicle ECU 145, the DC/DC converter 140 converts the electric power rectified by the rectifier 130 to a voltage level of the electricity storage device 150 and outputs the electric power to the electricity storage device 150. Note that when the electric power is received from the power supply apparatus 200 while the vehicle is running, the DC/DC converter 140 may convert the electric power rectified by the rectifier 130 to the system voltage and directly supply the electric power to the PCU 160. The DC/DC converter 140 is not necessary. A configuration may be employed, in which the alternating current received by the secondary coil 120 is rectified by the rectifier 130 and is then directly supplied to the electricity storage device 150.

[0022] The electricity storage device 150 is a rechargeable direct-current power supply and examples thereof include secondary batteries, such as the lithium-ion batteries and the nickel-hydrogen batteries. The electricity storage device 150 stores the electric power supplied from the DC/DC converter 140 and the regenerated electric power generated by the electric motor 170. The electricity storage device 150 supplies the stored electric power to the PCU 160. A large-capacitance capacitor can be used as the electricity storage device 150. The electricity storage device 150 is not limited as long as it functions as an electric power buffer that can temporarily store the electric power supplied from the power supply apparatus 200 and the regenerated electric power generated by the electric motor 170 and supply the stored electric power to the PCU 160.

[0023] The PCU 160 drives the electric motor 170 with the electric power output from the electricity storage device 150 or the electric power directly supplied from the DC/DC converter 140. The PCU 160 rectifies the regenerated electric power generated by the electric motor 170 to output the electric power to the electricity storage device 150, thereby charging the electricity storage device 150. The motor 170 is driven by the PCU 160 and generates the vehicle driving power and outputs the driving power to the driving wheels. The electric motor 170 generates electricity with the use of the kinetic energy received from the driving wheels and, in the case of a hybrid vehicle, from the engine (not shown), and outputs the generated electric power, including the regenerated electric power, to the PCU 160.

[0024] The vehicle ECU 145 controls the DC/DC converter 140 when the electric power is supplied from the power supply apparatus 200 to the electric vehicle 100. The vehicle ECU 145 controls the voltage between the rectifier 130 and the DC/DC converter 140 to a predetermined target voltage by controlling the DC/DC converter 140, for example. The vehicle ECU 145 also controls the PCU 160 based on the driving conditions of the vehicle and the state of charge (SOC) of the electricity storage device 150 while the vehicle is running.

[0025] The electrical equipment 400 installed in the electromagnetic shielding case 190 comprehensively means the electrically driven units that are installed for the purpose of abnormality monitoring, indications, and cooling in the electromagnetic shielding case 190. Examples of the electrical equipment 400 include a cooling fan, an electrically driven cooling pump, indicators, such as light emitting diodes (LEDs), and a temperature sensor for detecting the inner temperature.

[0026] The power supply apparatus 200 includes an alternating-current (AC) power supply 210, a high-frequency AC power driver 220, and a coil unit 280. The coil unit 280 includes a primary coil 230, which functions as an electromagnetic induction coil, and a primary self-resonant coil 240. The coil unit 280 is accommodated in the electromagnetic shielding case 250. The electromagnetic shielding case 250 also accommodates electrical equipment 500 etc. in addition to the coil unit 280.

[0027] The AC power supply 210 is a power supply provided externally to the vehicle, which is, for example, a system power supply. The high-frequency AC power driver 220 converts the electric power received from the AC power supply 210 to a high-frequency AC power and supplies the high-frequency AC power to the primary coil 230. The frequency of the high-frequency AC power generated by the high-frequency AC power driver 220 is, for example, one megahertz to several dozen megahertz.

[0028] The primary coil 230 is provided coaxially with the primary self-resonant coil 240 and can be magnetically coupled to the primary self-resonant coil 240 via electromagnetic induction. The primary coil 230 supplies, to the primary self-resonant coil 240 via electromagnetic induction, the high-frequency AC power supplied from the high-frequency AC power driver 220.

[0029] The primary self-resonant coil 240 is disposed near the ground surface, for example. The primary self-resonant coil 240 is also an LC resonant coil, both ends of which are free ends. Note that although both ends of the primary self-resonant coil 240 are free ends, an additional capacitor (not shown) may be connected across both ends of the primary self-resonant coil 240. The primary self-resonant coil 240 is capable of at least one of transmitting electric power to the vehicle 100 by resonating with the secondary self-resonant coil 110 of the electric vehicle 100 via electromagnetic field and receiving electric power transmitted from the secondary self-resonant coil 110. When the primary self-resonant coil 240 receives electric power from the secondary self-resonant coil 110, the primary coil 230 receives the electric power from the primary self-resonant coil 240 via electromagnetic induction.

[0030] The number of turns of the primary self-resonant coil 240 is appropriately set based on the distance between the primary self-resonant coil 240 and the secondary self-resonant coil 110 of the electric vehicle 100, the resonance frequency of the primary self-resonant coil 240 and the secondary self-resonant coil 110, etc. so that the Q factor (Q > 100, for example), the degree of coupling, kappa, etc. become large.

[0031] The electrical equipment 500 installed in the electromagnetic shielding case 250 comprehensively means the electrically driven units that are installed for the purpose of abnormality monitoring, indications, and cooling in the electromagnetic shielding case 250. Examples of the electrical equipment 500 include a cooling fan, an electrically driven cooling pump, indicators, such as LEDs, and a temperature sensor for detecting the inner temperature, which are electrical loads.

[0032] FIG. 2 is a diagram for explaining the principle of electric power transmission using the resonance method. Referring to FIG. 2, in the resonance method, as in the case of the resonance of two tuning forks, electric power is transmitted from one coil to the other coil via electromagnetic field due to the resonance of two LC resonant coils having the same eigenfrequency in the electromagnetic field (near field).

[0033] Specifically, a primary coil 320 is connected to a high-frequency AC power supply 310 and the high-frequency AC power of one megahertz to several dozen megahertz is supplied, via electromagnetic induction, to the primary self-resonant coil 330 that is magnetically coupled to the primary coil 320. The primary self-resonant coil 330 is an LC resonator using the inductance of the coil itself and the stray capacitance, which includes the capacitance of a capacitor when the capacitor is connected to the coil, and the primary self-resonant coil 330 resonates with the secondary self-resonant coil 340 having the resonance frequency the same as that of the primary self-resonant coil 330 via electromagnetic field (near field). As a result, energy (electric power) is transferred from the primary self-resonant coil 330 to the secondary self-resonant coil 340 via electromagnetic field. The energy (electric power) transferred to the secondary self-resonant coil 340 is received, via electromagnetic induction, by the secondary coil 350 that is magnetically coupled to the secondary self-resonant coil 340, and is then supplied to the load 360. The electric power transmission by the resonance method is performed when the Q factor that indicates the intensity of resonance of the primary self-resonant coil 330 and the secondary self-resonant coil 340 is greater than 100, for example.

[0034] The correspondences between FIG. 1 and FIG. 2 will now be explained.

The AC power supply 210 and the high-frequency AC power driver 220 in FIG. 1 correspond to the high-frequency AC power supply 310 in FIG. 2. The primary coil 230 and the primary self-resonant coil 240 in FIG. 1 correspond to the primary coil 320 and the primary self-resonant coil 330 in FI 2. The secondary self-resonant coil 110 and the secondary coil 120 in FIG. 1 correspond to the secondary self-resonant coil 340 and the secondary coil 350 in FIG. 2. The rectifier 130 and the devices downstream therefrom in FIG. 1 are comprehensively represented by the load 360 in FIG. 2.

[0035] Thus, when the electricity storage device 150 is charged, first, electric power is supplied from the primary coil 230 to the primary self-resonant coil (first self-resonant coil) 240 via electromagnetic induction. Then, the secondary self-resonant coil (second self -resonant coil) 110 receives electric power from the primary self-resonant coil 240 via the electromagnetic field resonance. The electric power received by the secondary self-resonant coil 110 is transferred to the secondary coil 120 via electromagnetic induction. The electric power transferred to the secondary coil 120 is supplied to the electricity storage device 150 via the rectifier 130 and the converter 140.

[0036] On the other hand, when the electric power stored in the electricity storage device 150 is supplied to the external load, first, electric power is supplied to the secondary coil 120 via the converter 140 and the rectifier 130. Then, the electric power is supplied from the secondary coil 120 to the secondary self-resonant coil 110 via electromagnetic induction. The electric power supplied to the secondary self-resonant coil 110 is transmitted to the primary self-resonant coil 240 via the electromagnetic field resonance. The electric power received by the primary self-resonant coil 240 is supplied to the primary coil 230 via electromagnetic induction. The electric power supplied to the primary coil 230 is supplied to the external load via a driver or the like.

[0037] FIG. 3 is a diagram showing relations between the distance from the electric current source (magnetic current source) and the intensity of the electromagnetic field. Referring to FIG. 3, the electromagnetic field includes three components. The curve kl represents a component that is inversely proportional to the distance from the electromagnetic wave source and is called "radiation field". The curve k2 represents a component that is inversely proportional to the square of the distance from the electromagnetic wave source and is called "induction field". The curve k3 represents a component that is inversely proportional to the cube of the distance from the electromagnetic wave source and is called "static field".

[0038] The "static field" is a component such that the intensity of the electromagnetic wave steeply decreases with the distance from the electromagnetic -wave source. In the resonance method, energy (electric power) is transmitted with the use of the near field (evanescent field), in which the "static field" is dominant. Specifically, by resonating a pair of resonators (a pair of LC resonant coils, for example) haying the same eigenfrequency with each other in the near field, in which the "static field" is dominant, energy (electric power) is transmitted from one resonator (primary self-resonant coil) to the other resonator (secondary self-resonant coil). Because the "static field" does not transmit energy far away, the resonance method can transmit energy with lower energy loss as compared to the case where electromagnetic waves are used that transmit energy (electric power) with the use of the "radiation field" that transmits energy far away.

[0039] FIG. 4 is a schematic diagram showing the electromagnetic shielding cases 190 and 250 shown in FIG. 1 and the surrounding structure.

[0040] As shown in FIG. 4, a coil case 191 is disposed in the electromagnetic shielding case 190. The secondary self-resonant coil 110 and the secondary coil 120 shown in FIG. 1 etc. are accommodated in the coil case 191. An opening 195 is formed on the lower side of the electromagnetic shielding case 190. An electromagnetic shielding material (electromagnetic shield) is attached to the electromagnetic shielding case 190. A low impedance material, such as thin copper film, is used as the electromagnetic shielding material.

[0041] The electromagnetic shielding case 190 suppresses the leakage of the electromagnetic field formed by the secondary self-resonant coil 110 and the primary self-resonant coil 240 to the vehicle side.

[0042] A coil case 291 is disposed in the electromagnetic shielding case 250.

The coil case 291 accommodates the primary self-resonant coil 240 and the primary coil 230 shown in FIG. 1 etc. An opening 255 is formed on the upper side of the electromagnetic shielding case 250. An electromagnetic shielding material is attached also to the electromagnetic shielding case 250.

[0043] FIG. 5 is a perspective view of the coil case 191. As shown in FIG. 5, the coil case 191 includes a pot portion 193 formed in a shape of a cylinder having a bottom and a top plate portion 192 disposed on the pot portion 193. The top plate portion 192 is fixed to the lower surface of a floor panel of a vehicle, for example. The coil case 191 is disposed so as to project downward from the lower surface of the floor panel.

[0044] FIG. 6 is an exploded perspective view of the coil case 191 shown in FIG. 5. As shown in FIG. 6 a bobbin 196 is disposed in the pot portion 193 formed in the shape of a cylinder having a bottom. The bobbin 196 is formed in a cylindrical shape and a plurality of plates 197 are attached to the outer circumferential surface of the bobbin 196 so as to be spaced apart from each other in the circumferential direction. The secondary self-resonant coil 110 is supported by the plates 197. Note that the plates 197 are arranged at regular intervals and the number thereof is six or eight, for .example.

[0045] The coil unit includes the secondary self-resonant coil 110, the plates 197 that support the secondary self-resonant coil 110, and the bobbin 196 that functions as the support member that supports the plates 197. The plates 197 are made of resin.

[0046] Because the area, in which the plates 197 are in contact with the secondary self-resonant coil 110, is small, it is possible to reduce the dielectric loss. Thus, it is possible to improve the power transfer efficiency when electric power is transferred between the secondary self-resonant coil 110 and the primary self-resonant coil 240 in FIG. 1.

[0047] In addition, the contact area between the secondary self-resonant coil 110¹ and the plates 197 is small and therefore the area, in which the secondary self-resonant coil 110 is in contact with the air, is large, so that it is possible to cool the secondary self-resonant coil 110 well.

[0048] FIG. 7 is a perspective view showing part of the circumferential surface of the bobbin 196. As shown in FIG. 7, insertion grooves 198 are formed in the outer circumferential surface of the bobbin 196. The plates 197 are fitted into the insertion grooves 198.

[0049] In FIGS. 6 and 7, a plurality of bosses 199 are formed on the inner circumferential surface of the bobbin 196 at intervals.

[0050] A threaded hole is formed in each of the bosses 199. The pot portion 193 and the bobbin 196 are fixed to each other with bolts 194, which are screwed into the threaded holes in the bosses 199. The bolts 194 are an example of fixing means, or fixing members, and are detachable from the top plate portion 192, the pot portion 193, and the bobbin 196 as needed.

[0051] In addition, the top plate portion 192 and the bobbin 196 are also fixed to each other with the bolts 194. The plates 197 are sandwiched between the top plate portion 192 and the bottom of the pot portion 193 and secured by the top plate portion 192 and the bottom of the pot portion 193. In order to firmly fix the plates 197, the plates 197 are fixed to the bobbin 196 with the use of the fixing members, such as bolts, from the inner circumferential surface side of the bobbin 196.

[0052] Thus, the plates 197 can be detached from the bobbin 196 by detaching the top plate portion 192 and the pot portion 193 from the bobbin 196 and removing the bolts or the like fixing the plates 197.

[0053] Because the plates 197 are provided detachably from the bobbin 196 in this way, when the secondary self-resonant coil 110 that has been installed is replaced with another secondary self-resonant coil 110 of a different length, it is possible to install the secondary self-resonant coil 110 of the different length by changing the plates 197 only.

[0054] When the grooves for installation of the secondary self-resonant coil 110 are formed in the outer circumferential surface of the bobbin 196, the bobbin 196 itself has to be replaced with another bobbin. In the coil case 191 according to the embodiment, however, changing the plates 197 makes it possible to use various secondary self-resonant coils 110, so that it is possible to easily changing the secondary self-resonant coil 110.

[0055] In FIG. 6, the plates 197 also support the secondary coil 120. The plates 197 maintain the distance between the secondary coil 120 and the secondary self-resonant coil 110.

[0056] The distance between the secondary coil 120 and the secondary self-resonant coil 110 affects the distance between the coil unit 180 and the coil unit 280, at which electric power can be transferred therebetween, and affects the power transfer efficiency. [0057] Because the plates 197 support the secondary coil 120 and the secondary self-resonant coil 110 so that the distance between the secondary coil 120 and the secondary self-resonant coil 110 is kept at a predetermined distance, it is possible to keep the distance between the coil unit 180 and the coil unit 280, at which electric power can be transferred therebetween, within a predetermined range while maintaining the power transfer efficiency within a predetermined range.

[0058] In FIG. 6, each of the secondary self-resonant coil 110 and the secondary coil 120 is formed so as to extend spirally around an imaginary central axis. Each of the secondary self-resonant coil 110 and the secondary coil 120 is not a multi-layered coil but a single-layered coil. In the example shown in FIG. 6, the secondary self-resonant coil 110 is formed so as to extend circularly and in the imaginary central axis direction along the direction of extension of the secondary self-resonant coil 110. The secondary self-resonant coil 110 is coiled with a certain space provided so that the coil wire of the secondary self-resonant coil 110 is not brought into contact with itself. The primary self-resonant coil 330 is formed similarly to the secondary self-resonant coil 110.

[0059] The secondary coil 120 is also formed so as to extend circularly and in the imaginary central axis direction along the direction of extension of the secondary coil 120. The secondary coil 120 is also coiled with a certain space provided so that the coil wire of the secondary coil 120 is not brought into contact with itself. The primary coil is formed similarly to the secondary coil 120. The imaginary central axis of the secondary self-resonant coil 110 and the imaginary central axis of the secondary coil 120 coincide with each other and the secondary coil 120 is disposed on the vehicle side with respect to the secondary self-resonant coil 110.

[0060] A plurality of the plates 197 are provided on the outer circumferential surface of the bobbin 196 at intervals and recesses for receiving the secondary self-resonant coil 110 and the secondary coil 120 are formed in each of the plates 197.

[0061] In the example shown in FIG. 6, the number of turns of the secondary self-resonant coil 110 is less than one and the number of turns of the secondary coil 120 is about one. [0062] Note that when a capacitor is connected across both ends of the secondary self-resonant coil 110, both ends of the secondary self-resonant coil 110 are formed to extend to the inner side of the bobbin 196 through the outer circumferential surface of the bobbin 196 and connected to the capacitor disposed in the bobbin 196.

[0063] FIG. 8 is a side view of the plate 197. As shown in FIG. 8, recesses 201 for receiving the secondary coil 120 and recesses 202 for receiving the secondary self-resonant coil 110 are formed in the plate 197.

[0064] FIG. 9 is a side view of the plate 197 that is provided at another position than the position of the plate 197 shown in FIG. 8. As shown in FIGS. 8 and 9, positions of the recesses 201 and the recesses 202 vary depending on the plates. The recess 202 is formed to have a width greater than the diameter of the secondary self-resonant coil 110. The diameter of the secondary self-resonant coil 110 is the diameter of the cross section of the coil wire thereof, the cross section taken along the plane perpendicular to the direction, in which the coil wire of the secondary self-resonant coil 110 extends.

[0065] FIG. 10 is a front view of the plate 197. In FIG. 10, when the secondary self-resonant coil 110 is replaced with another secondary self-resonant coil of a different length, the inclination angle of the secondary self-resonant coil 110 changes.

[0066] Since the width of the recess 202 is greater than the diameter of the secondary self-resonant coil 110, the recess 202 can accommodate the secondary self-resonant coil 110 even when the inclination angle of the secondary self-resonant coil 110 is larger. In addition, the secondary self -resonant coil 110 can contact either of the upper inner wall surface of the recess 202 and the lower inner wall surface thereof, so that it is possible to suppress deformation of the secondary self-resonant coil 110.

[0067] Thus, when the secondary self-resonant coil 110 that has been installed is replaced with another secondary self-resonant coil 110 of a slightly different length, it is possible to easily change the secondary self-resonant coil 110 even without changing the plates 197.

[0068] Similarly, the recess 201 is formed to have a width greater than the diameter of the secondary coil 120. The diameter of the secondary coil 120 is the diameter of the cross section of the coil wire thereof, the cross section taken along the plane perpendicular to the direction, in which the coil wire of the secondary coil 120 extends.

[0069] FIG. 11 is a perspective view showing a modification of the plate 197.

In the example shown in FIG. 11, the plate 197 has a support portion 204, in which the recesses 201 and 202 are formed, and a base portion 205 that is provided so as to be continuous with the support portion 204.

[0070] The base portion 205 is inserted into an insertion groove 206 formed in the bobbin 196. The base portion 205 is formed so that the farther the position is from the support portion 204, the greater the width of the base portion 205 becomes. The width of the insertion groove- 206 also increases from the outer circumferential surface side of the bobbin 196 toward the inner circumferential surface side of the bobbin 196. With the plate 197 shown in FIG. 11, the inner wall surface of the insertion groove 206 supports the base portion 205, so that it is possible to prevent the plate 197 from coming off the bobbin 196.

[0071] Although the description of this embodiment has been made for an example, in which the number of turns in the secondary self-resonant coil 110 is approximately one, the number of turns in the secondary self-resonant coil 110 may be more than one as shown in FIG. 12.

[0072] FIG. 13 is a side view of the plate 197 attached to the bobbin 196 shown in FIG. 12. In the plate 197, a plurality of recesses 202 that receive the secondary self-resonant coil 110 are formed at intervals.

[0073] FIG. 14 is a perspective view showing a second modification of the coil unit. In an example shown in FIG. 14, the plurality of plates 197 are arranged on an inner circumferential surface of the bobbin 196 at intervals. The secondary self-resonant coil 110 and the secondary coil 120 are disposed inside the bobbin 196 and supported by the plates 197.

. [0074] According to the example shown in FIG. 14, the bobbin 196 functions as a support member for supporting the plates 197 and functions as a protection case for protecting the secondary self-resonant coil 110 and the secondary coil 120.

[0075] FIG. 15 is a perspective view showing a third modification of the coil unit. In the example shown in FIG. 15, the secondary self-resonant coil 110 is formed so as to have a U-shaped cross section. When the secondary self-resonant coil 110 has a U-shaped cross section, the surface area of the secondary self-resonant coil 110 is greater than the surface area of the secondary self-resonant coil 110 that has a circular cross section.

[0076] When electric power is transferred, a high-frequency alternating current flows in the secondary self-resonant coil 110 and therefore, by securing a large surface area of the secondary self-resonant coil 110, it is possible to keep the resistance of the secondary self-resonant coil 110 low.

[0077] . The secondary self-resonant coil 110 with a U-shaped cross section is higher in rigidity and is more resistant to deformation than the coil with a circular cross section. Thus, there is no need to wind the secondary self-resonant coil 110 around the plates 197 with a tension applied to the secondary self-resonant coil 110. Thus, it suffices that the plates 197 have rigidity such that the plates 197 can hold the secondary self-resonant coil 110 when the secondary self-resonant coil 110 is installed.

[0078] Thus, in the example shown in FIG. 15, the bobbin that supports the plates 197 is omitted. One ends of the plates 197 are inserted into groove portions formed in the top plate portion 192. The top plate portion 192 and the pot portion 193 are joined with bolts or the like (not shown) and the plates 197 are fixed by being sandwiched between the top plate portion 192 and the pot portion 193. Specifically, in the example shown in FIG. 15, the top plate portion 192 functions as a support member for supporting the plates 197. The plates 197 are provided detachably from the top plate portion 192. Thus, when the secondary self-resonant coil 110 and the secondary coil 120 are replaced with another secondary self-resonant coil 110 of a different length and another secondary coil 120 of a different length, it is possible to install the secondary self-resonant coil 110 of the different length and the secondary coil 120 of the different length by changing the plates 197.

[0079] As described above, when the secondary coil 110 with high rigidity is used, the bobbin may be omitted and it is possible to reduce the number of parts.

[0080] In the example shown in FIG. 6, each of the secondary coil 120 and the secondary self-resonant coil 110 is a single-layered coil. Thus, when the secondary coil 120 and the secondary self-resonant coil 110 are installed, the bobbin 196 is prepared, to which the plates 197 have been attached. Two coils are installed from the side of the bobbin 196. Then, one coil is used as the secondary self-resonant coil 110 and wiring is connected to ends of the other coil to use the other coil as the secondary coil 120.

[0081] As another example of the method Of installing the secondary coil 120 etc., the method as described below may be employed. In FIGS. 6 and 8, the recesses 201 formed in the plates 197 are spirally arranged. Thus, when the secondary coil 120 is installed, first, a coil spirally extending is prepared. The coil may be sequentially inserted into the recesses 201 in the plates 197 by screwing the coil. After the coil has been inserted into the recesses 201, wiring or the like is connected to the ends of the coil and the ends are fixed. In this way, the installation of the secondary coil 120 is completed. When the secondary self-resonant coil 110 is installed, similarly, a coil spirally extending is prepared. The recesses 202 are also spirally arranged, so that the coil can be sequentially inserted into the recesses 202 in the plates 197 by screwing the coil.

[0082] According to this installation method, by adjusting the amount of screwing of the coils, it is possible to adjust the distance between the secondary self-resonant coil 110 and the secondary coil 120. The distance between the secondary coil 120 and the secondary self-resonant coil 110 affects the power transfer efficiency and the distance, over which electric power can be transferred. Thus, it is possible to change the distance between the secondary self-resonant coil 110 and the secondary coil 120 according to the vehicle type.

[0083] In addition, with regard to the secondary self-resonant coil 110, both ends of which are free ends, it is possible to adjust the distance between the secondary self-resonant coil 110 and the secondary coil 120 by screwing the secondary self-resonant coil 110 even after the secondary coil 120 is fixed.

[0084] While embodiments of the invention have been described above, it should be understood that the embodiments described herein are merely examples and should not be understood as restrictive. The scope of the invention is indicated by the claims and it is intended to include all the modifications within the scope of the claims and the equivalent thereof. The above numerical values etc. are examples and the invention is not limited to those represented by the above numerical values and ranges.

[0085] The invention can be applied to a coil unit, a non-contact electric-power receiving apparatus, a non-contact electric-power transmitting apparatus, and a vehicle. In particular, the invention is suitable for a coil unit or the like capable of at least one of transmission and reception of electric power via the electromagnetic field resonance.

Claims

CLAIMS:

1. A coil unit characterized by comprising:

a second self-resonant coil capable of at least one of transmission and reception of electric power to and from a first self-resonant coil via electromagnetic field resonance, the first self-resonant coil being externally provided;

a plate that supports the second self -resonant coil; and

a support member that supports the plate.

2. The coil unit according to claim 1, wherein the plate is provided detachably from the support member.

3. The coil unit according to claim 1 or 2, wherein a recess that receives the second self-resonant coil is formed in the plate and a width of the recess is greater than a diameter of a cross section of the second self-resonant coil.

4. The coil unit according to any one of claims 1 to 3, wherein the support member is a bobbin that is disposed inside the second self-resonant coil, and the plate is provided on an outer circumferential surface of the bobbin.

5. The coil unit according to any one of claims 1 to 3, wherein the support member is a bobbin that is disposed outside the second self-resonant coil, and the plate is provided on an inner circumferential surface of the bobbin.

6. The coil unit according to any one of claims 1 to 3, wherein

the support member is disposed on each side of the second self-resonant coil in an axial direction of the second self-resonant coil;

a plurality of the plates are arranged along the second self-resonant coil so as to extend in the axial direction, each of the plates being connected to the support member on each side of the second self-resonant coil in the axial direction; and

the second self-resonant coil has a high rigidity such that the second self-resonant coil can maintain its form independently.

7. The coil unit according to any one of claims 1 to 6, further comprising an electromagnetic induction coil that is capable of at least one of transmitting electric power via electromagnetic induction to the second self-resonant coil that transmits electric power to the first self-resonant coil and receiving electric power via electromagnetic induction from the second self-resonant coil that receives electric power from the first self-resonant coil, wherein the electromagnetic induction coil is supported by the plate.

8. A non-contact electric-power receiving apparatus characterized by comprising the coil unit according to any one of claims 1 to 7, wherein the non-contact electric-power receiving apparatus is capable of charging an electricity storage device.

9. A vehicle characterized by comprising:

the non-contact electric-power receiving apparatus according to claim 8; and the electricity storage device.

10. A non-contact electric-power transmitting apparatus characterized by comprising the coil unit according to any one of claims 1 to 7, wherein electric power is supplied from an external power supply.