Lead wire, non-contact power transmission device and non-contact power supply system

Abstract

The lead wire (12) of the present invention is characterized by having a first conductor foil (12a) extending along the extension direction of the lead wire (12), a second conductor foil (12b) extending parallel to the first conductor foil (12a) along the extension direction of the lead wire (12), and an insulator (12c) arranged between the first conductor foil (12a) and the second conductor foil (12b).

Description

[Technical field]

[0001] The present invention relates to a lead wire, a contactless power transmission device having the lead wire, and a contactless power supply system having the contactless power transmission device. [Background technology]

[0002] Conventionally, non-contact power supply has been known. In non-contact power supply, power is generated in a coil on the power receiving side by the action of a coil on the power transmitting side. A battery is connected to the coil on the power receiving side, and power is stored in the battery. Patent Document 1 discloses a power supply coil unit (non-contact power transmission device) used for non-contact power supply. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-233107 A Summary of the Invention [Problem to be solved by the invention]

[0004] In a non-contact power supply device such as that described in Patent Document 1, a lead wire (power cable) is used to transmit power from an AC power source (high frequency power source) to a coil. From the viewpoint of reducing AC resistance, a Litz wire, which is made by twisting a large number of thin enameled wires in multiple stages, is often used as the lead wire. Since the enameled wire that constitutes the Litz wire is thin, it is possible to suppress an increase in conductor resistance caused by the skin effect when an AC current is passed through it. In addition, since the Litz wire has multiple enameled wires twisted together, it is possible to suppress an increase in conductor resistance due to the proximity effect.

[0005] The above-mentioned Litz wire is manufactured, for example, using polyurethane copper wire (enameled wire) made by covering a conductor wire with a diameter of 0.1 mm with polyurethane as follows. First, multiple enameled wires are twisted together. Next, the twisted wires are twisted in multiple stages to obtain the Litz wire. Thus, to obtain a litz wire suitable for a lead wire, multiple twisting steps are required, resulting in high manufacturing costs. Also, to connect the litz wire to a coil or an AC power source, it is necessary to remove the enamel coating from many enameled wires, which requires special terminal processing (for example, fusing processing that generates heat with a large current).

[0006] An object of the present invention is to provide a lead wire that can suppress an increase in AC resistance and has excellent manufacturing costs and ease of terminal processing, a non-contact power transmission device having the lead wire, and a non-contact power supply system having the non-contact power transmission device. [Means for solving the problem]

[0007] According to one aspect of the present invention for solving the above problem, A lead wire, A first conductor foil extending along the extending direction of the lead wire; a second conductor foil extending alongside the first conductor foil along the extending direction of the lead wire; an insulator disposed between the first conductor foil and the second conductor foil; A lead wire is provided, comprising:

[0008] According to another aspect of the present invention for solving the above problem, An AC power source; A coil unit, a lead wire electrically connecting the AC power supply and the coil unit; having There is provided a contactless power transmitting device, characterized in that the lead wire is the lead wire described above.

[0009] According to another aspect of the present invention for solving the above problem, There is provided a contactless power supply system including the contactless power transmission device described above. Effect of the Invention

[0010] According to the present invention, it is possible to provide a lead wire that can suppress an increase in AC resistance and has excellent manufacturing costs and ease of terminal processing, a non-contact power transmission device having the lead wire, and a non-contact power supply system having the non-contact power transmission device. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1A is a schematic diagram of a contactless power supply system according to an embodiment, and FIG. 1B is a schematic diagram of a contactless power transmitting device. [Diagram 2] 2A and 2B are cross-sectional views of a lead wire according to an embodiment. [Diagram 3] FIG. 3 is a graph showing the relationship between frequency and conductor resistance. [Figure 4] FIG. 4 is a partially enlarged graph of the graph in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] A non-contact power supply system, a non-contact power transmission device, and a lead wire according to an embodiment of the present invention will be described below. However, the embodiment described below is merely an example, and the present invention is not limited thereto. Note that the non-contact power supply system and the non-contact power transmission device of the present invention can be used to charge a battery mounted on an electric vehicle, a plug-in hybrid vehicle, or the like in a non-contact state. In this specification, the term "to" indicating a numerical range means that the upper and lower limits of the range are included.

[0013] [Non-contact power supply system] Fig. 1A is a schematic diagram showing a state in which power is being contactlessly fed to a battery 3 of an electric vehicle 2 using a contactless power feeding system 1 according to the present embodiment. Fig. 1B is a schematic diagram showing the internal structure of a contactless power transmitting device 10 included in the contactless power feeding system 1 shown in Fig. 1A.

[0014] 1A and 1B, the contactless power transmission device 10 has a power source 11, a lead wire 12, and a coil unit 13. In the contactless power transmission device 10, a current supplied from the power source 11 flows through the lead wire 12 and then through the coil unit 13. Due to the action of the coil unit 13 through which the current flows, a current is generated in the coil 4 for receiving power that the electric vehicle 2 has, and the battery 3 that the electric vehicle 2 has is contactlessly supplied with power.

[0015] (Non-contact power transmission device) The non-contact power transmitting device 10 included in the non-contact power supply system 1 will be described below. As described above, the non-contact power transmission device 10 includes the power source 11, the lead wire 12, and the coil unit 13. Here, the lead wire 12 according to the present embodiment does not include a Litz wire but includes a conductor foil. The details of the lead wire 12 will be described later. Each component of the non-contact power transmission device 10 will be described below.

[0016] <power supply) The power source 11 is an electric energy source for the contactless power transmission device 10. In the present embodiment, the power source 11 is an AC power source, and the current supplied to the circuit is AC. From the viewpoint of efficient power supply, the power source 11 preferably passes an AC current at the resonant frequency of the contactless power supply system 1. When the contactless power transmission device 10 is used in the contactless power supply system 1 of the electric vehicle 2, the resonant frequency is generally around 85 kHz (80 kHz to 90 kHz). Therefore, the power source 11 is preferably capable of passing an AC current of around 85 kHz (80 kHz to 90 kHz), and more preferably is capable of passing an AC current of 85 kHz.

[0017] Lead Wire As shown in Fig. 1B, lead wire 12 is electrically connected to power source 11 and coil unit 13 to form a circuit. Fig. 2A is a cross-sectional view of such lead wire 12, specifically, a cross-sectional view taken along line AA in Fig. 1B.

[0018] 1B and 2A, lead wire 12 has first conductor foil 12a, second conductor foil 12b, and insulator 12c disposed between first conductor foil 12a and second conductor foil 12b. In this embodiment, lead wire 12 further has sheath 12d. Each of these will be described below.

[0019] The first conductor foil 12a and the second conductor foil 12b are the conductors of the lead wire 12. In this specification, the term "conductor foil" refers to a plate-shaped conductor. The length (length in the direction in which the lead wire extends) and width (length in the direction perpendicular to the extension and thickness directions of the lead wire) of the conductor foil are greater than the thickness of the conductor foil. The first conductor foil 12a and the second conductor foil 12b may be made of any material (conductor) having electrical conductivity, for example, a metal. Examples of metals include copper and copper alloys. In this embodiment, the material of the first conductor foil 12a and the second conductor foil 12b is copper. That is, the first conductor foil 12a and the second conductor foil 12b are copper foils. The surfaces of the first conductor foil 12a and the second conductor foil 12b are smooth.

[0020] The first conductor foil 12a and the second conductor foil 12b extend along the extension direction of the lead wire 12. The first conductor foil 12a and the second conductor foil 12b are arranged side by side such that one of the two main surfaces of each foil faces each other. Here, the "main surfaces" refers to the two relatively wide surfaces (the front surface and the back surface) of the conductor foil. The main surfaces are surfaces perpendicular to the thickness direction of the conductor foil and extend in the width and length directions of the conductor foil.

[0021] The distance between the first conductor foil 12a and the second conductor foil 12b arranged side by side as described above (the distance between the two opposing main surfaces) is preferably set so that an increase in AC resistance when an AC current is passed through the foil is suppressed by the proximity effect. From this viewpoint, the distance between the first conductor foil 12a and the second conductor foil 12b is preferably 1.5 mm or less. On the other hand, if the distance between the first conductor foil 12a and the second conductor foil 12b is too close, the possibility of a short circuit occurring increases. From this viewpoint, the distance between the first conductor foil 12a and the second conductor foil 12b is preferably, for example, 0.5 mm or more.

[0022] The thickness of each of the first conductor foil 12a and the second conductor foil 12b is preferably set so as to suppress an increase in AC resistance due to the skin effect when an AC current is passed through the foil. The skin effect increases as the frequency of the AC current increases, increasing the resistance. The thickness of each of the first conductor foil 12a and the second conductor foil 12b may be set appropriately according to the frequency of the AC current. For example, when the contactless power transmitting device 10 is used to charge an electric vehicle, an AC current of about 85 kHz (e.g., 80 kHz to 90 Hz), which is a resonant frequency, is applied from the power source 11. When a current of a frequency of about 85 kHz is applied to the copper foil, the skin depth is 0.227 mm. The skin depth is the depth at which the current flowing is 37% of the surface of the copper foil through which the maximum current flows. For this reason, in order to suppress the skin effect, it is preferable that the thickness of each of the first conductor foil 12a and the second conductor foil 12b is, for example, 0.5 mm or less. On the other hand, if the foil is too thin, the cross-sectional area becomes small, making it difficult for current to flow. From this viewpoint, it is preferable that the thickness of each of the first conductor foil 12a and the second conductor foil 12b is, for example, 0.1 mm or more.

[0023] There are no particular limitations on the width of each of the first conductor foil 12a and the second conductor foil 12b. The upper limit of each of the widths of the first conductor foil 12a and the second conductor foil 12b is, for example, 100 mm or less, and the lower limit of each of the widths is, for example, 10 mm or more.

[0024] There are no particular limitations on the manner in which the first conductor foil 12a and the second conductor foil 12b are electrically connected to the power source 11 and the coil unit 13. For example, as shown in Fig. 1B, one end of each of the first conductor foil 12a and the second conductor foil 12b may be connected to a connection terminal of the power source 11 via a rivet 6, and the other end of each of the first conductor foil 12a and the second conductor foil 12b may be connected to a connection terminal of the coil unit 13 via a rivet 6. Alternatively, for example, holes may be drilled in the first conductor foil 12a and the second conductor foil 12b, and the first conductor foil 12a and the second conductor foil 12b may be screwed to the connection terminal.

[0025] The insulator 12c is disposed between the first conductor foil 12a and the second conductor foil 12b, and performs an insulating function to prevent a short circuit between the first conductor foil 12a and the second conductor foil 12b. There are no particular limitations on the insulator 12c as long as it can perform this function.

[0026] 2A, in this embodiment, first conductor foil 12a, insulator 12c, and second conductor foil 12b are laminated in this order, so that insulator 12c is disposed between first conductor foil 12a and second conductor foil 12b. Insulator 12c is plate-shaped and extends in the direction in which lead wire 12 extends.

[0027] 2A, the length in the width direction of the insulator 12c is longer than the length in the width direction of the first conductor foil 12a and the length in the width direction of the second conductor foil. As a result, when the three components are laminated, the insulator 12c has ends that protrude on both sides in the width direction relative to the first conductor foil 12a and the second conductor foil 12b. Two more insulators 12c are laminated so as to sandwich the three components thus laminated. The insulator 12c laminated so as to sandwich it is also longer in the width direction relative to the first conductor foil 12a and the second conductor foil 12b, and has ends that protrude on both sides in the width direction. The ends of the two laminated insulators 12c sandwiched between the first conductor foil 12a and the second conductor foil 12b are bonded to the end of the insulator 12c disposed between the first conductor foil 12a and the second conductor foil 12b. In this manner, the first conductor foil 12a and the second conductor foil 12b covered with the insulator 12c can be obtained. The method for bonding the ends of the insulator 12c is not particularly limited. Examples of the bonding method include bonding using an adhesive, heat fusion, ultrasonic welding, and the like.

[0028] The manner in which the insulator 12c is disposed between the first conductor foil 12a and the second conductor foil 12b is not limited to the example shown in FIG. 2A above, and may be, for example, as shown in FIG. 2B. That is, as shown in Fig. 2B, the periphery of each of the first conductor foil 12a and the second conductor foil 12b is covered with an insulator 12c. Then, the first conductor foil 12a and the second conductor foil 12b covered with the insulator 12c are laminated. In this manner, the insulator 12c may be disposed between the first conductor foil 12a and the second conductor foil 12b.

[0029] The insulator 12c may be formed by extrusion molding or by applying tape.

[0030] The material of the insulator 12c is not particularly limited as long as it can perform an insulating function. Examples of the material of the insulator 12c include resins. Examples of the resins include thermoplastic resins. Examples of the material of the insulator 12c include polyethylene terephthalate (PET), polyvinyl chloride (PVC), polyethylene (PE), and polypropylene (PP).

[0031] The thickness of the insulator 12c arranged between the first conductor foil 12a and the second conductor foil 12b is preferably a thickness that generates a proximity effect between the first conductor foil 12a and the second conductor foil 12b. From this viewpoint, the thickness of the insulator 12c arranged between the first conductor foil 12a and the second conductor foil 12b is preferably 1.0 mm or less. On the other hand, if the thickness of the insulator 12c is too thin, there is a possibility that sufficient insulating function cannot be obtained. From this viewpoint, the thickness of the insulator 12c is preferably 0.1 mm or more.

[0032] The sheath 12d covers the first conductor foil 12a, the second conductor foil 12b, and the insulator 12c. The sheath 12d is an optional configuration and may or may not be present. In this embodiment, the lead wire 12 has the sheath 12d. The lead wire 12 covered with the sheath 12d is used as a lead cable.

[0033] The sheath 12d extends in the extending direction of the lead wire 12. The material of the sheath 12d is preferably insulating. Examples of the material of the sheath 12d include resin. Examples of the resin include thermoplastic resin. The material of the sheath 12d may be the same as the material of the insulator 12c.

[0034] <Coil unit> Coil unit 13 is electrically connected to lead wire 12. When a current is supplied to coil unit 13 via lead wire 12, a magnetic field is generated in coil 13a of coil unit 13, and the generated magnetic field acts on coil 4 for receiving power to generate a current.

[0035] 1B, in this embodiment, coil unit 13 has coil 13a, capacitor 13b, and housing 13c. Each of these will be described below.

[0036] Coil 13a is formed by winding a linear conductor. In this embodiment, the linear conductor is an enameled wire, and the enameled wire is wound in a plane.

[0037] The basic design of coil 13a, such as the number of turns, may be appropriately adjusted so as to achieve a desired resonance frequency (e.g., 85 kHz) in relation to other components. In this embodiment, coil 13a is sealed with resin within housing 13c.

[0038] The capacitor 13b is electrically connected to the coil 13a, and together with the coil 13a, constitutes a resonant circuit of the non-contact power transmitting device 10, generating a resonance phenomenon. The resonant frequency of the resonant circuit is determined mainly depending on the inductance of the coil 13a and the electric capacity of the capacitor 13b. Therefore, it is preferable that the combined capacity of the capacitor 13b is set so that the resonant frequency of the resonant circuit of the non-contact power transmitting device 10 approaches a desired frequency (e.g., 85 kHz). The number of the capacitors 13b is not particularly limited and is appropriately set according to the required combined capacity, etc. In this embodiment, a plurality of capacitors 13b are arranged on each of two boards. The board on which the plurality of capacitors 13b are arranged is supported by a pedestal and accommodated in a predetermined space in the housing 13c.

[0039] Capacitor 13b may be connected in parallel or in series to coil 13a. In the present embodiment, capacitor 13b is arranged in series with lead wire 12 and coil 13a. That is, capacitor 13b is arranged between coil 13a and each of first conductor foil 12a and second conductor foil 12b.

[0040] <housing> The housing 13c accommodates the coil 13a and the capacitor 13b. It is preferable that the housing 13c can protect the accommodated coil 13a and the resonance capacitor 13b from the external environment. In this embodiment, the coil unit 13 is buried in the ground. Therefore, it is preferable that the housing 13c can protect the coil 13a and the capacitor 13b in the ground. Specifically, it is preferable that the housing 13c has a waterproof function. In addition, it is preferable that the coil 13a and the capacitor 13b are sealed with resin in the housing 13c. This makes the coil 13a and the capacitor 13b less susceptible to the effects of condensation and the like. In addition, the insulation performance is improved.

[0041] The material of the housing 13c is not particularly limited as long as it can adequately protect the coil 13a and the capacitor 13b. Examples of the material of the housing 13c include polycarbonate, polypropylene, and polyphenylene sulfide (PPS). Examples of the resin that seals the coil 13a and the capacitor 13b include silicone resin, epoxy resin, and urethane resin. From the viewpoint of heat resistance, silicone resin is preferable.

[0042] (effect) The lead wire 12 according to the present embodiment has the first conductor foil 12a and the second conductor foil 12b as conductors, but does not have a Litz wire. This eliminates the disadvantages of using a Litz wire as a conductor, such as the need for a complicated twisting operation during manufacturing and the need for special terminal processing during connection. In addition, by using the first conductor foil 12a and the second conductor foil 12b, it is possible to suppress an increase in AC resistance by utilizing the proximity effect while reducing the influence of the skin effect. In addition, the insulator 12c is easy to remove, and the first conductor foil 12a and the second conductor foil 12b can be easily exposed, making it easy to make an electrical connection. In addition, in the installation in the power supply system, it can be installed as a single lead wire 12 (a single lead cable when the sheath 12d is included), and terminal processing can be performed on site. EXAMPLES

[0043] An experiment was conducted to investigate the difference in resistance to alternating current when conductor foil is used and when Litz wire is used. The conductor foil used was copper foil with a thickness of 0.3 mm, width of 50 mm, and length of 2 m. The Litz wire used was a 2 m long Litz wire made by twisting together 2,000 enameled wires with a diameter of 0.1 mm. Specifically, the Litz wire was obtained by twisting several wires together and then twisting them in multiple stages.

[0044] The above copper foil was covered with a 0.5 mm thick resin tape to form an insulator, and a coated copper foil was obtained. The resin tape was made of polyethylene. The coated copper foil was folded in the center in the length direction, and the two coated copper foils were overlapped so as to be in contact with each other, to obtain the lead wire of Sample 1. In this lead wire of Sample 1, an insulator having a thickness of 1 mm, which is derived from two pieces of 0.5 mm thick tape, is placed between the two copper foils (see FIG. 2B). The coated copper foil was folded in the center in the length direction, and two coated copper foils were overlapped with a 100 mm thick polystyrene foam plate placed between them to form the lead wire of Sample 2. In the lead wire of Sample 2, an insulator having a thickness of 101 mm, which is derived from two pieces of 0.5 mm thick tape and a 100 mm thick polystyrene foam plate, was placed between the two copper foils.

[0045] On the other hand, a lead wire having a litz wire for comparison was obtained as follows: the above litz wire was bent in the center in the length direction, and the distance between the two bent litz wires was set to 1 mm to obtain the lead wire of sample 3. The above litz wire was also bent in the center in the length direction, and a 100 mm thick polystyrene foam plate was placed between the two bent litz wires to obtain the lead wire of sample 4.

[0046] A power source was connected to both ends of the lead wires of Samples 1 to 4 obtained as described above, and the conductor resistance was measured when an AC current with a frequency of 0 to 2000 kHz was passed through the lead wires. The measurement results of the conductor resistance are shown in the graph of FIG. As can be seen from the graph in Figure 3, the lead wires of samples 1 and 2, which use copper foil as the conductor, have lower conductor resistance than the lead wires of samples 3 and 4, which use lead wire as the conductor. In particular, the higher the frequency, the greater the difference in conductor resistance between samples 1 and 2 and samples 3 and 4. This is presumably because the copper foil is thin, suppressing the skin effect, in which high-frequency currents concentrate on the surface of the conductor, and thus suppressing the increase in resistance. Furthermore, it is presumed that a proximity effect is obtained because the copper foils are arranged side by side.

[0047] The graph in Figure 4 is a partial enlargement of the graph in Figure 3, and shows the conductor resistance at frequencies from 0 to 200 kHz. As can be seen from Figure 4, Sample 2, which uses copper foil as the conductor and has a distance of 100 mm between the two copper foils, has a higher resistance at frequencies of approximately 120 kHz or less than Samples 3 and 4, which use Litz wire. For this reason, when using conductor foil as the conductor and passing an AC current with a frequency of 120 kHz or less, it is preferable that the distance between the two copper foils is less than 100 mm, and more preferably 1.5 mm or less. [Industrial Applicability]

[0048] The lead wire, the contactless power transmission device, and the contactless power supply system of the present invention can be used, for example, for contactless power supply in automobiles. The lead wire of the present invention may also be used for purposes other than contactless power supply systems, and can be used in various devices that require power supply. [Explanation of symbols]

[0049] 1. Wireless power supply system 2. Electric vehicles 3 Battery 4, 13a coil 6 Rivets 10. Non-contact power transmission device 11 Power supply 12 Lead Wire 12a First conductor foil 12b Second conductor foil 12c Insulator 12d Sheath 13 Coil unit 13b Capacitor 13c Housing

Claims

1. A lead wire used in a non-contact power transmitting device, A first conductor foil extending along the extension direction; a second conductor foil extending alongside the first conductor foil along the extending direction; an insulator disposed between the first conductor foil and the second conductor foil; having The thickness of each of the first conductor foil and the second conductor foil is 0.1 mm to 0.5 mm; A lead wire, characterized in that the distance between the first conductor foil and the second conductor foil is 0.5 mm to 1.5 mm.

2. 2. The lead wire according to claim 1, wherein the insulator is disposed between one main surface of the first conductor foil and one main surface of the second conductor foil.

3. 2. The lead wire according to claim 1, wherein the first conductor foil, the insulator, and the second conductor foil are laminated.

4. 2. The lead wire according to claim 1, wherein the first conductor foil and the second conductor foil each have a thickness of 0.1 mm to 0.3 mm.

5. 2. The lead wire according to claim 1, wherein the conductor foil is a copper foil.

6. An AC power source; A coil unit, a lead wire electrically connecting the AC power supply and the coil unit; having The lead wire is the lead wire according to any one of claims 1 to 5. Non-contact power transmission device.

7. 7. The non-contact power transmission device according to claim 6, wherein the frequency of the AC power source is 80 to 90 kHz.

8. A contactless power supply system comprising the contactless power transmission device according to claim 6.