WO2010032116A1

WO2010032116A1 - Contactless power supply system

Info

Publication number: WO2010032116A1
Application number: PCT/IB2009/006874
Authority: WO
Inventors: Yasushi Futabatake; Hiroshi Maeda; Kouichi Teraura; Youji Endo; Yukihiro Matsunobu; Masato Toki; Shinji Hara; Hironobu Hori
Original assignee: Panasonic Electric Works Co. Ltd.
Priority date: 2008-09-22
Filing date: 2009-09-18
Publication date: 2010-03-25
Also published as: KR20110047247A; CN102159423B; TW201021354A; CN102159423A; KR101258003B1; TWI397236B

Abstract

A contactless power supply system includes a feeder line through which a high-frequency current flows and a pickup unit inductively coupled to the feeder line. The contactless power supply system is configured to supply electric power to a load by an electromotive force induced in the pickup unit. The pickup unit includes a tubular core circumferentially surrounding the feeder line and a coil formed of a coil wire wound on the core. The core is provided with an inner surface, an outer surface and an opening extending in an axial direction of the feeder line so that at least the feeder line passes through the opening in a radial direction. At least one of the inner surface and the outer surface of the core is formed into a curved surface shape.

Description

CONTACTLESS POWER SUPPLY SYSTEM

Field of the Invention

The present invention relates to a contactless power supply system including a pickup unit inductively coupled to a high-frequency current flowing feeder line, the system being designed to supply electric power to a load by an electromotive force induced in the pickup unit.

Background of the Invention

Contactless power supply systems of this kind are disclosed in, e.g., Japanese Patent Laid-open Publication Nos. 2003-528555, 11-192866 and 2004-120880 and Japanese Patent No. 3263421. In these contactless power supply systems, a high-frequency current flowing feeder line is installed to extend along a movement track for a travel unit. A pickup unit inductively coupled to the feeder line is arranged in the travel unit. Electric power is supplied to a load (e.g., an electric motor for moving the travel unit) by an electromotive force induced in the pickup unit .

The pickup unit includes a tubular core circumferentially surrounding the feeder line and a coil formed of a coil wire wound around the core. Most of the magnetic flux generated around the feeder line passes through the core, thereby increasing the electromotive force induced in the coil . The core has an opening extending in the axial direction of the feeder line so that at least the feeder line can pass radially through the opening. This makes it easy to mount or remove the pickup unit to or from the feeder line.

The core employed in the conventional pickup unit has a substantially ⁿτz"~shaped cross section. As such, when the inner and outer peripheral surfaces of the core are formed of mutually-joining planar surfaces, the magnetic flux is partly leaked out in the plane-to-plane boundary portions (or the corner portions) . This poses a problem of reducing the efficiency of electric power transfer from the feeder line to the pickup unit . In addition, since the opening through which to insert the feeder line is formed in the core of the conventional pickup unit, the magnetic flux passing through the core is partly leaked out through the opening. An eddy current generated by the leaked magnetic flux flows through the metal components (e.g., the travel unit and the movement track) arranged near the pickup unit, which leads to a loss of electric power. This may possibly reduce the efficiency of transferring electric power to the pickup unit. In case where one of the two feeder lines incoming from and outgoing to a high frequency power supply is arranged inside the core with the other arranged near the pickup unit, the magnetic flux generated around the other feeder line cancels the magnetic flux passing the core through the opening. This may possibly reduce the efficiency of electric power transfer to the pickup unit. Although a magnetic shield is provided between the coil and the travel unit is the conventional cases, no consideration is given to the influence of the magnetic flux leaked out from the opening of the core or the influence of the magnetic flux generated around the feeder line arranged outside the core.

Summary of the Invention

In view of the above, the present invention provides a contactless power supply system capable of enhancing the efficiency of electric power transfer from a feeder line to a pickup unit and increasing the quantity of electric power supplied.

The present invention further provides a contactless power supply system capable of reducing the influence of the magnetic flux leaked out from an opening of a core or the influence of the magnetic flux generated around a feeder line arranged outside the core.

The present invention also provides a contactless power supply system capable of stabilizing the high- frequency resistance of a coil.

In accordance with a first aspect of the present invention, there is provided a contactless power supply system including: a feeder line through which a high- frequency current flows ; and a pickup unit inductively coupled to the feeder line, the contactless power supply system being configured to supply electric power to a load by an electromotive force induced in the pickup unit, wherein the pickup unit includes a tubular core circumferentially surrounding the feeder line and a coil formed of a coil wire wound on the core, and wherein the core is provided with an inner surface, an outer surface and an opening extending in an axial direction of the feeder line so that at least the feeder line passes through the opening in a radial direction, at least one of the inner surface and the outer surface of the core being formed into a curved surface shape.

In accordance with a second aspect of the present invention, there is provided a contactless power supply system including: a feeder line through which a high- frequency current flows; and a pickup unit inductively coupled to the feeder line, the contactless power supply system being configured to supply electric power to a load by an electromotive force induced in the pickup unit, wherein the pickup unit includes a tubular core circumferentially surrounding the feeder line and a coil formed of a coil wire wound on the core in a single layer.

In accordance with a third aspect of the present invention, there is provided a contactless power supply system including: a feeder line through which a high- frequency current flows,- and a pickup unit inductively coupled to the feeder line, the contactless power supply system being configured to supply electric power to a load by an electromotive force induced in the pickup unit, wherein the pickup unit includes : a tubular core circumferentially surrounding the feeder line, the core being provided with an opening extending in an axial direction of the feeder line so that at least the feeder line passes through the opening in a radial direction, a coil formed of a coil wire wound on the core, and a magnetic shield body for covering the core and the coil, the magnetic shield body being made of a magnetic material with a high permeability.

In accordance with a fourth aspect of the present invention, there is provided a contactless power supply system including: a feeder line through which a high- frequency current flows,- and a pickup unit inductively coupled to the feeder line, the contactless power supply system being configured to supply electric power to a load by an electromotive force induced in the pickup unit, wherein the pickup unit includes: a tubular core circumferentially surrounding the feeder line, the core being provided with an opening extending in an axial direction of the feeder line so that at least the feeder line passes through the opening in a radial direction; a coil formed of a coil wire wound on the core, the feeder line including an incoming feeder line inserted into the core and an outgoing feeder line arranged outside the core; and a magnetic shield body made of a magnetic material with a high permeability, the magnetic shield body being arranged between the outgoing feeder line and the opening of the core.

In accordance with a fifth aspect of the present invention, there is provided a contactless power supply system including: a feeder line through which a high- frequency current flows,- and a pickup unit inductively coupled to the feeder line, the contactless power supply system being configured to supply electric power to a load by an electromotive force induced in the pickup unit, wherein the pickup unit includes a tubular core circumferentially surrounding the feeder line, a bobbin fitted to around the core and a coil formed of a coil wire wound on the bobbin, wherein the core is provided with inner and outer circumferential surfaces of curved surface shape and is formed to have a generally C-shaped cross section intersecting an axial direction of the core, and wherein the bobbin includes an outer circumferential surface and a plurality of positioning protrusions arranged on the outer circumferential surface of the bobbin in a circumferential direction of the core, the coil wire being held in holding portions formed between the positioning protrusions adjoining to each other.

Brief Description of the Drawings

The objects and features of the present invention will become apparent from the following description of embodiments, given in conjunction with the accompanying drawings , in which-.

Fig. IA is a partially cut-away section view showing a pickup unit of a contactless power supply system in accordance with a first embodiment of the present invention, Fig. IB is a view for explaining the magnetic flux passing through the core of the pickup unit shown in Fig. IA, and Fig. 1C is a view for explaining the magnetic flux passing through the core of a conventional pickup unit;

Figs . 2A and 2B are plan views showing another and further examples of the core of the pickup unit employed in the contactless power supply system;

Fig. 3A is a perspective view showing the overall configuration of the contactless power supply system, and Figs. 3B and 3C are section views showing a feeder line employed in the contactless power supply system;

Fig. 4 is a section view showing the major parts of a contactless power supply system in accordance with a second embodiment of the present invention;

Fig. 5 is a section view showing the major parts of a

- H — modified example of the contactless power supply system shown in Fig. 4 ;

Fig. 6 is a section view showing the major parts of another modified example of the contactless power supply system shown in Fig. 4 ;

Fig. 7 is a section view showing the major parts of a contactless power supply system in accordance with a third embodiment of the present invention;

Fig. 8 is a section view showing the major parts of a modified example of the contactless power supply system shown in Fig . 7 ;

Fig. 9 is a section view showing the major parts of another modified example of the contactless power supply system shown in Fig. 7; Fig. 1OA is a partially cut-away section view showing a pickup unit of a contactless power supply system in accordance with a fourth embodiment of the present invention, Fig. 1OB is a section view showing the major parts of a bobbin of the pickup unit shown in Fig. 1OA, and Fig. 1OC is a perspective view showing the bobbin of the pickup unit shown in Fig. 1OA;

Fig. 11 is a section view showing the major parts of a modified example of the bobbin shown in Fig. 1OB;

Fig. 12 is a section view showing the major parts of a pickup unit of a contactless power supply system in accordance with a fifth embodiment of the present invention; and

Figs . 13A and 13B are perspective views showing the major parts of the pickup unit of the contactless power supply system shown in Fig. 12, and Fig. 13C is a perspective view showing the major parts of a conventional pickup unit .

Detailed Description of the Preferred Embodiments

Hereinafter, certain preferred embodiments of the present invention will be described with reference to the accompanying drawings .

(First Embodiment) Referring to Fig. 3A, the contactless power supply system of the present embodiment includes a feeder line 100 installed in a loop shape, a high frequency power supply 110 for feeding a high-frequency current through the feeder line 100 and a pickup unit 1 inductively coupled to the feeder line 100. The pickup unit 1 supplies electric power to a load (e.g., an inverter or a motor) 111.

As shown in Fig. 3B, the feeder line 100 includes a conductor integrally formed by bending a metal plate and an insulating body 104 formed of a synthetic resin molded product of square tube shape, the conductor being covered with the insulating body 104. The conductor includes a cylindrical inner tube portion 101, a cylindrical outer tube portion 102 arranged outside the inner tube portion 101 and a connector portion 103 for interconnecting the inner tube portion 101 and the outer tube portion 102 in a concentric relationship with each other. In a typical columnar feeder line through which a high-frequency current flows, there exists a resistance (or a high-frequency resistance) attributable to the skin effect and the proximity effect as well as an electric resistance specific to the material

(e.g., a metal plate) of the conductor. When the dual tube type conductor shown in Fig. 3B is used as the feeder line 100, however, it is possible to reduce the high-frequency resistance and the electric power loss as compared to the columnar feeder line. It is not necessary that the feeder line be limited to the above structure. Moreover, the feeder line can be formed by various methods such as an extrusion molding of a metal, a process of pressing an inner tube portion having a connection portion into an outer tube portion, or the like. A modified example of the feeder line is shown in Fig. 3C. The feeder line 100' includes a conductor and an insulating body 104' which is a synthetic resin molding product having a square tube shape, the conductor being covered with the insulating body 104'. The conductor includes a cylindrical inner tube portion 101', a cylindrical outer tube portion 102' arranged outside the inner tube portion 101 and four connector portions 103' interconnecting the inner tube portion 101' and the outer tube portion 102' in a concentric relationship with, each other.

The pickup unit 1 includes a core 2, a coil 3, a bobbin 4, a magnetic shield body 5 and a power-receiving circuit unit 6. The power-receiving circuit unit 6 includes a capacitor cooperating with the coil 3 to form a resonance circuit, a constant-voltage circuit for converting the resonance voltage outputted from the resonance circuit to a constant voltage, and so forth. As shown in Fig. IA, the core 2 has inner and outer circumferential surfaces of curved or cylindrical surface shape and a substantially C-shaped cross section intersecting the axial direction (or the direction perpendicular to the paper surface) . The core 2 has mutually-facing opposite end portions 20 between which an opening 2a is formed. The opposite end portions 20 are greater in axially-taken cross section than the remaining portion (hereinafter referred to as a "body portion") 21 of the core 2. The bobbin 4 is formed of a synthetic resin molded product of square tube shape and is curved into an arc shape. The bobbin 4 is provided with outer flanges 40 at its circumferential opposite ends. The body portion 21 of the core 2 is halved into two body pieces at the diametrically opposite point from the opening 2a. Similarly, the bobbin 4 is bisected into two bobbin pieces. The core 2 shown in Fig. IA is fabricated by inserting the body pieces into the bobbin pieces and jointing the end portions of the body pieces together.

The coil 3 is formed by winding a coil wire with an insulating coating on the bobbin 4 in a single layer. The step difference between the opposite end portions 20 and the body portion 21 is set greater than the diameter of the coil wire so that the coil 3 should not move outwards beyond the opposite end portions 20 of the core 2. This makes it possible to reduce the magnetic flux leaked out of the opposite end portions 20 of the core 2 at the ends of the coil 3.

The magnetic shield body 5 is made of a magnetic metal material with high permeability to have a substantially cylindrical shape and is fitted to the outside of the core 2 and the coil 3. The magnetic shield body 5 has an axially- extending groove 5a communicating with the opening 2a of the core 2.

The feeder line 100 is inserted through the opening 2a and arranged inside the core 2. If a high-frequency current flows through the feeder line 100, a high-frequency magnetic field (or flux) is generated in a concentric circle pattern about the feeder line 100. Most of the magnetic flux flows through the core 2 along a circumferential direction. In a case that the inner and outer circumferential surfaces of the core 2' (see Fig. 1C) are formed of mutually joined _

planar surfaces as in the conventional case, namely in case where the core 2' has a substantially "^"-shaped cross section, the magnetic flux is partially leaked out of the core 2' in the plane-to-plane boundary portions (or the corner portions) as illustrated in Fig. 1C.

In the present embodiment, the core 2 has inner and outer circumferential surfaces of curved or cylindrical shape and a substantially C-shaped cross section intersecting the axial direction. Therefore, as can be seen in Fig. IB, the magnetic flux is hardly leaked in the portion other than the opening 2a. Thanks to this feature, it is possible to enhance the efficiency of electric power transfer from the feeder line 100 to the pickup unit 1 and to increase the quantity of electric power supplied, as compared to the core 2' of the conventional case shown in Fig. 1C. Although the inner and outer circumferential surfaces of the core 2 are all formed into a curved shape in the present embodiment, only the outer circumferential surface may be formed into a curved shape as illustrated in Fig. 2A or only the inner circumferential surface may be formed into a curved shape as illustrated in Fig. 2B. Regardless of which of these two shapes is employed in the core 2, it is possible for the inner circumferential surface or the outer circumferential surface to reduce leakage of the magnetic flux from the portion of the core 2 other than the opening 2a, as compared to the core 2' of the conventional case having a plurality of planar surfaces joined with each other. It is however apparent that the core 2 of the present embodiment shows electric power transfer efficiency greater than that of the two kinds of cores shown in Figs . 2A and 2B .

In case where one of the two feeder lines 100 incoming from and outgoing to the high frequency power supply 110 is arranged inside the core 2 and the other is arranged near the pickup unit 1, the magnetic flux generated around the other feeder line 100 may cancel the magnetic flux passing through the core 2. This may possibly reduce the efficiency of electric power transfer to the pickup unit 1. In the present embodiment, the core 2 and the coil 3 are covered with and magnetically shielded by the magnetic shield body 5. Thanks to this feature, it is possible to prevent the magnetic flux passing through the core 2 from being canceled by the external magnetic field (or flux) . This makes it possible to reduce the loss of electric power.

In the present embodiment, the opening 2a is formed in the core 2 of the pickup unit 1 so that the feeder line 100 can be easily inserted in and removed from the pickup unit 1. The magnetic resistance of the magnetic circuit is greatly increased in the portion (or gap) of the opening 2a. In view of this, the opposite end portions 20 facing toward each other with the opening 2a left therebetween are formed to have an axial cross section greater than that of the body portion 21. This ensures that the magnetic resistance in the opposite end portions 20 of the core 2 becomes smaller than that in the body portion 21, thereby reducing the magnetic flux leaked out from the core 2 through the opening 2a.

If the coil is formed by winding a coil wire in multiple layers, the high-frequency resistance of the coil may be increased by the proximity effect, consequently reducing the electric power transfer efficiency. In the present embodiment, the coil 3 is formed by winding the coil wire on the core 2 in a single layer. As compared to a case where the coil wire is wound in multiple layers, this assists in reducing the high-frequency resistance and eventually enhancing the electric power transfer efficiency. (Second Embodiment)

The contactless power supply system of this embodiment shares the basic configuration with the contactless power supply system of the first embodiment. Therefore, the component parts common to those of the first embodiment will be designated by the same reference characters and redundant descriptions thereof will be omitted.

In the present embodiment, one of the two feeder lines 100 incoming from and outgoing to the high frequency power supply 110 (the incoming feeder line) is arranged inside the core 2 and the other (outgoing feeder line) is arranged near the pickup unit 1. In this case, the magnetic flux generated around the outgoing feeder line 100 arranged outside the core 2 flows in the opposite direction to the magnetic flux generated around the incoming feeder line 100 arranged inside the core 2 and may possibly cancel the magnetic flux passing through the core 2. In the present embodiment, however, the core 2 and the coil 3 are covered with the magnetic shield body 5. This makes it possible to prevent the magnetic flux generated around the outgoing feeder line 100 from flowing through the core 2. As a result, it becomes possible to avoid reduction in the electric power transfer efficiency of the pickup unit 1.

The core 2 employed in the present embodiment has the opening 2a through which to insert the feeder line 100. Therefore, the magnetic flux passing through the core 2 is partially leaked through the opening 2a. The magnetic flux thus leaked causes an eddy current to flow through a conductive rail 200, which leads to a loss of electric power. This may possibly reduce the electric power transfer efficiency of the pickup unit 1. If the aperture 5a of the magnetic shield body 5 is openably closed by a shield cover 50 as shown in Fig. 5, it is possible to shield the magnetic flux otherwise passing through the opening 2a and to reduce the loss of electric power attributable to the eddy current generated by the leaked magnetic flux. The magnetic shield cover 50 is made of the same material as the magnetic shield body 5 and is formed into a band plate shape . The magnetic shield cover 50 is removably fitted to the groove 5a of the magnetic shield body 5. Instead of covering the core 2 and the coil 3 with the magnetic shield body 5, a magnetic shield body 5' removably attached to the opposite end portions 20 of the core 2 may be provided to close the opening 2a of the core 2 as shown in Fig. 6. In this case, it is equally possible to reduce the loss of electric power caused by the eddy current. (Third Embodiment) The contactless power supply system of this embodiment shares the basic configuration with the contactless power supply system of the second embodiment. Therefore, the component parts common to those of the second embodiment will be designated by the same reference characters and redundant descriptions thereof will be omitted.

As set forth in connection with the second embodiment, there is a fear that the magnetic flux passing through the core 2 may be reduced under the influence of the magnetic flux generated around the outgoing feeder line 100 arranged outside the core 2.

In the present embodiment, as shown in Fig. 7, a magnetic shield body 7 made of a magnetic material with high permeability is arranged between the outgoing feeder line 100 lying outside the core 2 and the opening 2a of the core 2. The magnetic shield body 7 is formed to have a generally L-shaped cross section and is fixed at its longitudinal opposite ends to the rail 200 so that the outgoing feeder line 100 can be accommodated between the magnetic shield body 7 and the rail 200.

Since the magnetic shield body 7 made of a magnetic material with high permeability is arranged between the outgoing feeder line 100 and the opening 2a of the core 2, it is possible to restrain the magnetic flux generated around the outgoing feeder line 100 from affecting the core 2 and the coil 3 of the pickup unit 1. Moreover, the magnetic shield body 7 arranged between the opening 2a of the core 2 and the rail 200 is capable of reducing the magnetic flux leaked from the opening 2a and interlinked with the rail 200. This makes it possible to reduce the loss of electric power attributable to the eddy current generated by the leaked magnetic flux. Alternatively, the magnetic shield body 7 may have a planar plate shape as shown in Fig . 8.

As shown in Fig. 9, if the core 2 and the coil 3 are covered with the magnetic shield body 5 employed in the second embodiment, it is possible to further restrain the magnetic flux generated around the outgoing feeder line 100 from affecting the core 2 and the coil 3 of the pickup unit 1. In addition, if the configuration of the present embodiment is combined with the configuration shown in Fig. 5 or Fig. 6 in which the opening 2a of the core 2 is closed by the magnetic shield cover 50 or the magnetic shield body 5' , it is possible to further reduce the loss of electric power attributable to the eddy current generated by the magnetic flux leaked from the opening 2a.

(Fourth Embodiment) The contactless power supply system of this embodiment shares the basic configuration with the contactless power supply system of the first embodiment. Therefore, the component parts common to those of the first embodiment will be designated by the same reference characters and redundant descriptions thereof will be omitted.

Referring to Figs. 1OA and 1OB, positioning protrusions 41 extending in the axial direction of the core 2 and protruding radially outwards are arranged side by side on the outer circumferential surface of the bobbin 4 along the circumferential direction of the core 2. These positioning protrusions 41 are divided into multiple protrusion sets, each of which includes two protrusions defining a holding portion 42 for holding the coil wire 30 of the coil 3 therein. The respective protrusion sets adjoining to one another are arranged in an equal interval so that the gap "a" between the adjoining strands of the coil wire 30 can be kept uniform.

The corner portions of the bobbin 4 , i.e., the border portions between the inner and outer circumferential surfaces and the side surfaces, are rounded (see Fig. 10C) .

The coil 3 is formed by winding a coil wire 30 with an insulating coating on the bobbin 4 in a single layer. The step difference between the opposite end portions 20 and the body portion 21 is set greater than the diameter of the coil wire 30 so that the coil 3 should not move outwards beyond the opposite end portions 20 of the core 2.

In the tubular core 2 of the present embodiment whose inner and outer circumferential surfaces are of a curved surface shape and whose cross section intersecting the axial direction is of a substantially C-shape, gaps are generated between the strands of the coil wire 30 on the outer circumferential surface while the coil wire 30 is densely wound on the inner circumferential surface. In the conventional case, variations exist in the gap size. This poses a problem in that the high-frequency resistance of the coil becomes unstable and the yield rate gets worse. In the present embodiment, the positioning protrusions 41 are arranged on the outer circumferential surface of the bobbin 4, and the space between the two positioning protrusions 41 of each of the protrusion sets is used as the holding portion 42 for holding the coil wire 30 therein. Therefore, the position of each strand of the coil wire 30 on the outer circumferential surface of the bobbin 4 is determined by the position of the holding portion 42. Thanks to this feature, the gap size between the strands of the coil wire 30 on the outer circumferential surface of the bobbin 4 becomes uniform, which assists in stabilizing the high-frequency resistance of the coil 3.

In the present embodiment, the corner portions of the bobbin 4 making contact with the strands of the coil wire 30 are rounded. This prevents the coil wire 30 from being damaged and severed by the portions of the bobbin 4.

In this regard, if the gap between the adjoining strands of the coil wire 30 becomes greater, it is possible to reduce the influence of the proximity effect and the high-frequency resistance of the coil 3. As shown in Fig. 11, the holding portions 42 arranged side by side along the circumferential direction of the bobbin 4 may be formed by alternately arranging first holding portions 42a and second holding portions 42b having a depth smaller than that of the first holding portions 42a. Use of this configuration makes it possible to increase the distance ^Xλb" between the adjoining strands of the coil wire 30 (b>a) . As a result, it is possible to reduce the influence of the proximity effect and the high-frequency resistance of the coil 3. (Fifth Embodiment) The contactless power supply system of this embodiment shares the basic configuration with the contactless power supply system of the first embodiment. Therefore, the component parts common to those of the first embodiment will be designated by the same reference characters and redundant descriptions thereof will be omitted.

Referring to Figs. 12 and 13, the contactless power supply system of the present embodiment includes a case 500 made of a synthetic resin molded product with an insulating property. The case 500 includes a first case portion 501 for accommodating the core 2 and the coil 3 and a second case portion 502 for accommodating a resonance circuit 60 excluding the coil 3. The first case portion 501 is formed to have a sustantially C-shaped cross section conforming to the shape of the core 2. The second case portion 502 is formed to have a rectangular box shape with one surface thereof opened.

The resonance circuit 60 includes a rectangular base substrate 61 arranged near the inner bottom surface of the second case portion 502 in a parallel relationship with the inner bottom surface, a plurality of sub-substrates 62 each having one or more capacitors C (two capacitors in the illustrated example) mounted thereto, a plurality of connectors 63 provided in the base substrate 61 and the sub- substrates 62. A conductive pattern (not shown) is formed on the surface of the base substrate 61. The terminals (not shown) of the coil 3 are pushed into the second case portion 502 from the first case portion 501 and are electrically connected to the conductive pattern. The sub-substrates 62 have a size much smaller than that of the base substrate 61. A pair of terminal pins 63b forming each of the connectors 63 protrudes from one end surface of each of the sub- substrates 62 (see Fig. 13A) . Two capacitors C are mounted on the front surface of each of the sub-substrates 62. A conductive pattern (not shown) for electrically interconnecting the terminals of the capacitors C and the terminal pins 63b is formed on the rear surface of each of the sub-substrates 62.

A plurality of jackets 63a, into which the terminal pins 63b can be inserted in a removable manner, is mounted on the surface of the base substrate 61 and is electrically connected to the coil 3 through the conductive pattern. In other words, the connectors 63 includes the jackets 63a and the terminal pins 63b. The coil 3 and the capacitors C are electrically connected to each other through the connectors 63, thereby providing the resonance circuit 60. Since the connectors 63 of this kind are well-known in the art, the detailed structure thereof will be omitted from illustration and description.

If a high-frequency current flows through the feeder line 100 inserted into the core 2 through the opening 2a, a high-frequency magnetic field (or flux) is generated concentrically about the feeder line 100. Most of the magnetic flux flows through the core 2 along a circumferential direction. As the magnetic flux varies with the high-frequency current, an induced electromotive force is generated in the coil 3. The induced electromotive force thus generated is amplified by the resonating action of the resonance circuit 60 including the coil 3 and the capacitors C. The resonance voltage outputted from the resonance circuit 60 is converted to a constant voltage by a constant- voltage circuit and is then supplied to the load 111.

If the capacitors C are directly mounted to the base substrate 61 as shown in Fig. 13C, in order to adjust the capacitance value of the capacitors C in the resonance circuit 60, it is required to take out the base substrate 61 from the second case portion 502, remove the solder from the terminals of the capacitors C, detach the capacitors C from the base substrate 61 and solder the terminals of the capacitors C to the base substrate 61. Moreover, if a user fails to adjust the capacitance value at one time, there is a need to repeatedly perform the adjustment task. This makes the adjustment task quite laborious. In the present embodiment, as shown in Figs. 13A and 13B, the sub-substrates 62 carrying the capacitors C can be attached to and detached from the base substrate 61 using the connectors 63. This makes it possible to adjust the capacitance value of the capacitors C with ease. As a result, it is possible to simplify the task of adjusting the resonance circuit 60 as compared to the prior art configuration shown in Fig. 13C.

The connectors 63 (including the jackets 63a and the terminal pins 63b) of the present embodiment are designed to interconnect the base substrate 61 and the sub-substrates 62 in such a way that the sub-substrates 62 remain perpendicular to the base substrate 61. This provides an advantage of reducing the size of the base substrate 61.

While the invention has been shown and described with respect to the embodiments, it will be understood by those skilled in the art that various changes and modification may be made without departing from the scope of the invention as defined in the following claims.

Claims

What is claimed is :

1. A contactless power supply system comprising: a feeder line through which a high-frequency current flows; and a pickup unit inductively coupled to the feeder line, the contactless power supply system being configured to supply electric power to a load by an electromotive force induced in the pickup unit, wherein the pickup unit includes a tubular core circumferentially surrounding the feeder line and a coil formed of a coil wire wound on the core, and wherein the core is provided with an inner surface, an outer surface and an opening extending in an axial direction of the feeder line so that at least the feeder line passes through the opening in a radial direction, at least one of the inner surface and the outer surface of the core being formed into a curved surface shape.

2. The system of claim 1, wherein both the inner surface and the outer surface of the core are formed into a curved surface shape and the core has a generally C-shaped cross section intersecting the axial direction.

3. The system of claim 1 or 2, wherein the core is provided with opposite end portions facing toward each other with the opening left therebetween, the opposite end portions of the core being greater in a cross section taken along the axial direction than the remaining portion of the core.

4. The system of any one of claims 1 to 3 , wherein the coil is formed by winding the coil wire on the core in a single layer.

5. The system of any one of claims 1 to 4, wherein pickup unit further includes a magnetic shield body for covering the outer surface of the core .

6. A contactless power supply system comprising: a feeder line through which a high-frequency current flows,- and a pickup unit inductively coupled to the feeder line, the contactless power supply system being configured to supply electric power to a load by an electromotive force induced in the pickup unit, wherein the pickup unit includes a tubular core circumferentially surrounding the feeder line and a coil formed of a coil wire wound on the core in a single layer.

7. A contactless power supply system comprising: a feeder line through which a high-frequency current flows; and a pickup unit inductively coupled to the feeder line, the contactless power supply system being configured to supply electric power to a load by an electromotive force induced in the pickup unit, wherein the pickup unit includes: a tubular core circumferentially surrounding the feeder line, the core being provided with an opening extending in an axial direction of the feeder line so that at least the feeder line passes through the opening in a radial direction, a coil formed of a coil wire wound on the core, and a magnetic shield body for covering the core and the coil, the magnetic shield body being made of a magnetic material with a high permeability.

8. A contactless power supply system comprising: a feeder line through which a high-frequency current flows; and a pickup unit inductively coupled to the feeder line, the contactless power supply system being configured to supply electric power to a load by an electromotive force induced in the pickup unit, wherein the pickup unit includes : a tubular core circumferentially surrounding the feeder line, the core being provided with an opening extending in an axial direction of the feeder line so that at least the feeder line passes through the opening in a radial direction; a coil formed of a coil wire wound on the core, the feeder line including an incoming feeder line inserted into the core and an outgoing feeder line arranged outside the core; and a magnetic shield body made of a magnetic material with a high permeability, the magnetic shield body being arranged between the outgoing feeder line and the opening of the core.

9. The system of claim 8 , wherein the pickup unit further includes a second magnetic shield body for covering the core and the coil, the second magnetic shield body being made of a magnetic material with a high permeability.

10. A contactless power supply system comprising: a feeder line through which a high-frequency current flows; and a pickup unit inductively coupled to the feeder line, the contactless power supply system being configured to supply electric power to a load by an electromotive force induced in the pickup unit, wherein the pickup unit includes a tubular core circumferentially surrounding the feeder line, a bobbin fitted to around the core and a coil formed of a coil wire wound on the bobbin, wherein the core is provided with inner and outer circumferential surfaces of curved surface shape and is formed to have a generally C-shaped cross section intersecting an axial direction of the core, and wherein the bobbin includes an outer circumferential surface and a plurality of positioning protrusions arranged on the outer circumferential surface of the bobbin in a circumferential direction of the core, the coil wire being held in holding portions formed between the positioning protrusions adjoining to each other.

11. The system of claim 10, wherein the holding portions are arranged side by side along a circumferential direction of the bobbin and includes first holding portions and second holding portions having a depth smaller than that of the first holding portions, the first holding portions and the second holding portions being arranged in an alternating manner.

12. The system of claim 10 or 11, wherein the bobbin includes rounded corner portions making contact with the coil wire.