JP2012147638A - Secondary side coil unit for noncontact electricity feeding and noncontact electricity feeding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a secondary side coil unit for noncontact electricity feeding that is reduced in thickness and capable of feeding electricity at high transmission efficiency.SOLUTION: A secondary side coil unit for noncontact electricity feeding comprises: a planar secondary coil (32) having an opposing face (32a) opposite to a primary coil (22) and a rear face (32b), which is reverse to the opposing face; and a magnetic sheet (38) so arranged as to cover the rear face of the secondary coil. The magnetic sheet comprises a first magnetic layer (38a) close to the secondary coil and a secondary magnetic layer (38b) that is arranged between the secondary coil and itself with the first magnetic layer in-between and is greater than the first magnetic layer in saturated magnetic flux density.

Description

  The present invention relates to a non-contact power supply secondary coil unit and a non-contact power supply device for supplying power to a portable electronic device or the like.

  In recent years, a non-contact power feeding device using electromagnetic induction between a primary (power feeding) coil and a secondary (power receiving) coil has been proposed as a power feeding device for portable electronic devices such as mobile communication terminals and digital cameras.

  A contactless power supply device applied to a portable electronic device or the like is required to be small, particularly thin, in addition to efficiency during power transmission. As a conventional technique related to a thin non-contact power feeding device, one using a planar spiral coil as a primary and secondary coil is known. In addition, a technique has been proposed in which a magnetic sheet is arranged outside the coil in order to suppress unwanted radiation due to the magnetic field generated from the coil, and a metal sheet is arranged outside the magnetic sheet in order to suppress unwanted radiation due to an electric field. Yes.

JP 2006-42519 A

  However, in recent contactless power supply devices, there is a demand for further thinning of the secondary unit combining the coil and the sheet and an improvement in power transmission efficiency, and the conventional magnetic sheet and metal sheet 2 are arranged. The secondary unit has a problem that it cannot sufficiently meet the demand. In particular, when the primary side unit is equipped with a magnet for alignment or the like, the secondary side unit is affected by the magnetic field of the primary side magnet. Met.

  This invention is made | formed in view of such a subject, The objective is to provide the secondary side coil unit for non-contact electric power feeding and non-contact electric power feeding apparatus which can implement | achieve thin electric power feeding with sufficient transmission efficiency.

The secondary coil unit for non-contact power feeding according to the present invention is:
A flat secondary coil having a facing surface facing the primary coil and a back surface opposite to the facing surface, and a magnetic sheet disposed to cover the back surface of the secondary coil,
The magnetic sheet is disposed between the first magnetic layer adjacent to the secondary coil and the secondary coil with the first magnetic layer interposed therebetween, and has a second saturation magnetic flux density higher than that of the first magnetic layer. And a magnetic layer.

  The secondary coil unit for non-contact power feeding according to the present invention adopts a magnetic sheet having a first magnetic layer and a second magnetic layer, so that the secondary coil unit for non-contact power feeding is thin as a whole, High power supply with high inductance.

Considering AC frequency in non-contact power supply, ferrite with good high frequency characteristics is considered suitable as a magnetic sheet, but ferrite has a relatively small saturation magnetic flux density, and has a problem that magnetic saturation tends to occur when it is thinned. . Moreover, as a general tendency, there is a trade-off relationship between the good high frequency characteristics and the high saturation magnetic flux density in soft magnetic materials. Therefore, the magnetic sheet according to the present invention is disposed on the side close to the secondary coil, and the high-frequency characteristics are imparted to the first magnetic layer having a small saturation magnetic flux density, and the first magnetic layer is disposed therebetween. The second magnetic layer having a saturation magnetic flux density larger than that of the first magnetic layer has a role of avoiding magnetic saturation while being thin. Since the first magnetic layer is disposed close to the primary coil and the secondary coil, the magnetic flux is transmitted within a range where magnetic saturation does not occur and the secondary coil inductance is increased. However, the saturation magnetic flux density is small and thin. The magnetic saturation may occur. However, since the magnetic sheet according to the present invention has the second magnetic layer disposed outside the first magnetic layer, even if the first magnetic layer is magnetically saturated, the remaining magnetic flux is transmitted by the second magnetic layer. In addition, the inductance of the secondary coil can be increased. That is, since the saturation magnetic flux density of the second magnetic layer is large, even if it is thin, it is difficult for the magnetic saturation to occur, and the generation of leakage magnetic flux can be effectively suppressed. Thus, the secondary coil unit according to the present invention can reduce the thickness of the entire magnetic sheet as compared with the case of the first magnetic layer alone.

Also, for example, in the secondary coil unit for non-contact power feeding according to the present invention, the first magnetic layer is a resin magnetic powder mixed layer composed of magnetic powder and a resin connecting the magnetic powder, or It may be a ferrite layer composed of ferrite,
The second magnetic layer may be a magnetic metal layer made of a non-oxidized magnetic metal.

  Ferrite and the like tend to have a low saturation magnetic flux density, but since the% conductivity is small and energy loss due to the generation of eddy currents tends to be small, the first magnetic layer is arranged close to the secondary coil, and as much as possible. By transmitting the magnetic flux, the inductance of the secondary coil can be increased. On the other hand, the second magnetic layer made of a metallic magnetic material or the like and having a high saturation magnetic flux density tends to have a high% conductivity and a large energy loss due to the generation of eddy currents. However, since the second magnetic layer is disposed outside the first magnetic layer, the magnetic flux transmitted through the second magnetic layer is suppressed, and the generation of eddy current associated therewith is suppressed. Therefore, the secondary coil unit having such a magnetic sheet suppresses a decrease in inductance of the secondary coil due to the generation of eddy current in the second magnetic layer, compared to the case of the second magnetic layer alone. Can do.

  In this way, the first magnetic layer is a resin magnetic powder mixed layer or a ferrite layer, and the second magnetic layer is a magnetic metal layer, thereby realizing a high-efficiency power supply having high inductance while being thin. The secondary coil unit can be easily manufactured.

  In the secondary coil unit for non-contact power feeding according to the present invention, it is preferable that the first magnetic layer has a lower% conductivity than the second magnetic layer. By reducing the% conductivity of the first magnetic layer disposed in the vicinity of the first and second cores, as described above, the secondary coil unit according to the present invention has an energy loss due to generation of eddy currents. It is possible to suppress power consumption and perform highly efficient power feeding.

  In addition, for example, the magnetic sheet is disposed between the second coil with the first magnetic layer and the second magnetic layer interposed therebetween, and the third magnetic layer is made of the same material as the first magnetic layer. You may have a layer further.

  The magnetic sheet of the present invention may have a two-layer structure of a first magnetic layer and a second magnetic layer, but a third magnetic layer formed of the same material as that of the first magnetic layer outside the second magnetic layer. It may further have a layer and may have a structure of three or more layers. That is, when a magnetic sheet is configured by combining two or more layers having different saturation magnetic flux densities, a layer having a low saturation magnetic flux density is divided into two and arranged on both sides of a layer having a high saturation magnetic flux density (second magnetic layer). May be. Even if the magnetic sheet has such a three-layer structure, the effect of increasing the inductance of the secondary coil is obtained as in the case where the thickness of the first magnetic layer is increased with the two-layer structure.

A non-contact power feeding device according to the present invention includes any of the above-described secondary coil units for non-contact power feeding,
A primary-side coil unit for non-contact power feeding that includes the primary coil and a magnet disposed in a central portion of the primary coil.

  The magnet of the primary side coil unit has effects such as alignment of the primary side coil unit and the secondary side coil unit, but there is a problem that the magnetic sheet is likely to be magnetically saturated by the magnetic flux of the magnet. However, as described above, the secondary coil unit includes the magnetic sheet including the first magnetic layer and the second magnetic layer. Therefore, the non-contact power feeding device according to the present invention reduces the thickness of the secondary coil unit. Highly efficient power supply can be achieved.

FIG. 1 is an exploded perspective view of a non-contact power feeding apparatus according to an embodiment of the present invention. 2 is a cross-sectional view of the non-contact power feeding apparatus shown in FIG. FIG. 3 is a cross-sectional view of a secondary coil unit according to the second embodiment of the present invention. FIG. 4 is a cross-sectional view of the secondary coil unit according to the embodiment. Fig.5 (a)-FIG.5 (c) are sectional drawings showing the arrangement | positioning state of the secondary side coil unit in the inductance measurement state of an Example. FIG. 6 is a graph showing the inductance measurement results of Sample 01 to Sample 03. FIG. 7 is a graph showing the inductance measurement results of Sample 03 to Sample 05. FIG. 8 is a graph showing the inductance measurement results of Sample 02 and Sample 04 to Sample 09. FIG. 9 is a graph showing the inductance measurement results of Sample 05, Sample 10, and Sample 11. FIG. 10 is a graph showing the inductance measurement results of Sample 04 and Samples 12 to 18.

  FIG. 1 is an exploded perspective view of a non-contact power supply apparatus 10 according to the first embodiment of the present invention. As shown in FIG. 1, the non-contact power supply apparatus 10 includes a primary side coil unit 20 that supplies power and a secondary side coil unit 30 that receives power.

  The primary coil unit 20 includes a primary coil 22, a magnet 26, and a magnetic body portion 28. The primary coil 22 is a flat spiral coil, and a primary coil hole 24 is formed at the center of the primary coil 22. A magnet 26 is disposed in the primary coil hole 24, and the primary coil 22 is formed so as to go around the outer periphery of the magnet 26.

  The primary coil 22 has a primary coil facing surface 22a that faces the secondary coil 32 when power is supplied, and a primary coil back surface 22b that is the opposite surface of the primary coil facing surface 22a. The magnetic body portion 28 is disposed on the primary coil back surface 22b so as to cover the primary coil back surface 22b.

  The secondary coil unit 30 includes a secondary coil 32 and a magnetic sheet 38. As the secondary coil 32, as in the case of the primary coil 22, a flat spiral coil or the like can be adopted, but it is not particularly limited.

  The secondary coil 32 is supplied with power from the primary coil 22 (receives power), and the secondary coil facing surface 32a that faces the primary coil 22 and the secondary coil back surface that is the opposite surface of the secondary coil facing surface 32a. 32b. A magnetic sheet 38 is disposed on the secondary coil back surface 32b so as to cover the secondary coil back surface 32b.

  2 assembles the primary side and secondary side coil units 20 and 30 shown in FIG. 1 and positions the secondary side coil unit 30 with respect to the primary side coil unit 20 in order to perform non-contact power feeding. It is sectional drawing showing the state which carried out. For example, when the non-contact power supply device 10 is used as a charging device for a battery 14 mounted on a mobile phone, the primary coil unit 20 is incorporated in a mobile phone charger, and the secondary coil unit 30 is a mobile phone. Embedded in. For example, the battery 14 accommodated in a metal case (aluminum or the like) is disposed on the back surface of the secondary coil unit 30. The primary side and secondary side coil units 20 and 30 are assembled by being housed in a resin case (not shown), respectively, but the primary side and secondary side coil units 20 and 30 are particularly assembled. It is not limited.

  When the secondary coil unit 30 is positioned with respect to the primary coil unit 20, the magnet 26 disposed in the primary coil hole 24 draws the central part of the secondary coil unit 30 and assists in positioning. Have a role to play. An adsorbent 36 made of a magnetic material is disposed in the secondary coil hole formed at the center of the secondary coil unit 30 in order to increase the pulling force of the secondary coil unit 30 by the magnet 26. However, it is not particularly limited.

  The primary coil 22 shown in FIGS. 1 and 2 is supplied with an AC voltage having a predetermined frequency during power feeding. The AC voltage supplied to the primary coil 22 is generated by converting a household AC voltage via an AC / DC converter or power transmission device mounted on the charger. The frequency of the AC voltage supplied to the primary coil 22 is not particularly limited, but can be about 100 to 200 kHz.

  The magnetic part 28 included in the primary coil unit 20 is arranged for the purpose of preventing leakage of magnetic flux from the primary coil 22 and forming a magnetic circuit (magnetic path). Although the magnetic body portion 28 is made of a soft magnetic material, the magnetic sheet 38 of the secondary side coil unit 30 is not required to be as thin as the magnetic sheet 38, so it is made of a ferrite sintered body in consideration of iron loss. Is preferred.

  The secondary coil 32 generates an alternating voltage by electromagnetic induction by the primary coil 22 when receiving power (when the primary coil 22 is fed). The AC voltage induced by the secondary coil 32 is converted into a DC voltage via a power receiving circuit mounted on the mobile phone and used for charging the battery 14 and the like.

  As shown in FIG. 2, the magnetic sheet 38 of the secondary coil unit 30 is disposed with the first magnetic layer 38 a sandwiched between the first magnetic layer 38 a close to the secondary coil 32 and the secondary coil 32. A second magnetic layer 38b. The second magnetic layer 38b has a higher saturation magnetic flux density than the first magnetic layer 38a. The first magnetic layer 38a preferably has a lower% conductivity than the second magnetic layer 38b.

  The first magnetic layer 38a and the second magnetic layer 38b are made of various materials including a magnetic material. For example, the first magnetic layer 38a is preferably a resin magnetic powder mixed layer composed of magnetic powder and a resin connecting the magnetic powder or a ferrite layer composed of ferrite (for example, a ferrite sintered body). The two magnetic layer 38b is preferably a magnetic metal layer made of a non-oxidized magnetic metal. Thereby, the magnetic sheet 38 in which the first magnetic layer 38a is smaller than the second magnetic layer 38b with respect to the saturation magnetic flux density and the% conductivity can be easily manufactured. Non-oxidized magnetic metals include iron, nickel, cobalt, alloys containing these, silicon steel, amorphous alloys, and the like.

  The secondary coil unit 30 having such a magnetic sheet 38 can not only suppress leakage magnetic flux but also suppress loss due to generation of eddy current while achieving a reduction in thickness. That is, if the magnetic sheet is produced only by the first magnetic layer 38a that is a resin magnetic powder mixed layer or a ferrite layer, the first magnetic layer 38a has a low saturation magnetic flux density, and thus the magnetic sheet cannot be thinned. This is because, when power is supplied from the primary coil unit 20, the thickness required for the first magnetic layer 38a not to be magnetically saturated becomes large. In particular, when the primary side coil unit 20 has the magnet 26, it is affected by the magnetic bias by the magnet 26, so that the thickness required for the first magnetic layer 38a not to be magnetically saturated is further increased. .

  On the other hand, if the magnetic sheet is produced only by the second magnetic layer 38b, which is a magnetic metal layer, the magnetic metal layer has a high% conductivity, so that energy loss due to the generation of eddy current increases and transmission efficiency decreases. . However, the magnetic sheet 38 according to the present embodiment overcomes these problems by disposing the second magnetic layer 38b outside the first magnetic layer 38a.

  That is, since the magnetic sheet 38 includes not only the first magnetic layer 38a but also the second magnetic layer 38b having a high saturation magnetic flux density, the thickness required for preventing the magnetic sheet 38 from being magnetically saturated is suppressed. Thereby, the secondary side coil unit 30 according to the present embodiment can prevent a decrease in inductance of the secondary coil 32 due to magnetic saturation while reducing the thickness.

  Further, in the magnetic sheet 38, the second magnetic layer 38b is disposed at a position farther from the primary coil 22 and the secondary coil 32 than the first magnetic layer 38a. Accordingly, the magnetic flux in the electromagnetic induction is preferentially transmitted by the first magnetic layer 38a close to the secondary coil 32 and transmitted through the second magnetic layer 38b in a range where the first magnetic layer 38a is not magnetically saturated. Magnetic flux is suppressed. As a result, the secondary coil unit 30 according to the present embodiment takes advantage of the characteristics of the second magnetic layer 38b that the saturation magnetic flux density is large, while giving high frequency characteristics to the first magnetic layer 38a and causing loss due to eddy current. Can be suppressed, and a decrease in inductance of the secondary coil 32 due to eddy current loss can be prevented.

  The ratio of the first magnetic layer 38a to the second magnetic layer 38b in the magnetic sheet 38 is such that the secondary coil 32 is larger in consideration of the fact that the loss due to the generation of eddy current is proportional to the square of the current value. It is preferably determined so as to obtain an inductance. Further, the initial magnetic permeability μi of the first magnetic layer 38a and the second magnetic layer 38b is not limited to a specific range in order to obtain the effects of the invention. For example, the initial magnetic permeability of the first magnetic layer 38a It is appropriate that μi is 5 to 30,000, and the initial permeability μi of the second magnetic layer 38b is about 5 to 200,000.

  FIG. 3 is a cross-sectional view of the secondary coil unit 40 according to the second embodiment of the present invention. The secondary coil unit 40 is the same as the secondary coil unit 30 according to the first embodiment except that the magnetic sheet 48 is different.

  The magnetic sheet 48 of the secondary coil unit 40 includes a first magnetic layer 48a, a second magnetic layer 48b, and a third magnetic layer 48c. The first magnetic layer 48a and the second magnetic layer 48b are the same as the first magnetic layer 38a and the second magnetic layer 38b according to the first embodiment.

  The third magnetic layer 48 c is disposed with the first magnetic layer 48 a and the second magnetic layer 48 b sandwiched between the secondary coil 32. The third magnetic layer 48c is made of the same material as the first magnetic layer 48a, and has a lower saturation magnetic flux density than the second magnetic layer 48b. The first magnetic layer 48a and the third magnetic layer 48c are a resin magnetic powder mixed layer composed of magnetic powder and a resin connecting the magnetic powder or a ferrite layer composed of ferrite (for example, a ferrite sintered body). The second magnetic layer 38b is preferably a magnetic metal layer made of a non-oxidized magnetic metal.

  Like the magnetic sheet 48, the layer (resin magnetic powder mixed layer or ferrite layer) having a small saturation magnetic flux density may be divided into two and disposed on both sides of the layer (magnetic metal layer) having a large saturation magnetic flux density. Even if the magnetic sheet 48 has a three-layer structure as shown in FIG. 3, the inductance of the secondary coil 32 is increased in the same manner as when the thickness of the first magnetic layer 38a is increased with the two-layer structure (see FIG. 2). There is an effect to increase.

  In the first and second embodiments, the planar shapes (shapes viewed from the stacking direction) of the first to third magnetic layers 38a, 38b, 48a to 48c are substantially the same as shown in FIGS. Although there may be, it is not limited to this. For example, the planar shape of the second magnetic layers 38b and 48b may be larger than that of the first magnetic layers 38a and 48a or the third magnetic layer 48c. Since the second magnetic layers 38b and 48b have portions that extend outside the outer periphery of the first magnetic layers 38a and 48a or the third magnetic layer 48c, the extended portions serve as shock buffering portions. It is possible to prevent the secondary coil unit 40 from being damaged by an impact or the like.

  EXAMPLES Hereinafter, although this invention is demonstrated based on an Example, this invention is not limited to these Examples.

Sample 01 to Sample 11
First, eleven types of secondary coil units 50 according to Sample 01 to Sample 11 were prepared, and the inductance was measured for each sample. As shown in FIG. 4, each sample has a secondary coil 52 and a magnetic sheet 58 that covers the back surface of the secondary coil 52. However, the secondary coil unit according to the sample 01 has only the secondary coil 52.

  In each sample 01 to sample 11, the same secondary coil 52 was used. The secondary coil 52 was a rectangular flat spiral coil having an outer peripheral shape of 40 × 30 mm. A secondary coil hole of 25 × 15 mm is formed at the center of the secondary coil 52. The effective number of turns of the secondary coil 32 was 31.

  The magnetic sheet 58 shown in FIG. 4 used a different material for each sample. In the embodiment, each layer of the magnetic sheet 58 will be described as a magnetic layer A 58a, a magnetic layer B 58b, and a magnetic layer C 58c in order from the side close to the secondary coil 52 to the outside. The planar shape of the magnetic sheet 58 was 48 × 32 mm. Table 1 shows data of the magnetic sheets 58 according to the samples 01 to 11 together with the inductance measurement results.

  As shown in Table 1, the magnetic sheet 58 used in Sample 02 to Sample 05 has only the magnetic layer A 58a and has a single-layer structure. The magnetic layer A58a of the sample 02 is a magnetic metal layer made of non-oxidized metal and has a thickness of 0.3 mm. The magnetic layer A58a of Sample 03 to Sample 05 is a ferrite layer formed of a ferrite sintered body, and has a thickness of 0.3 mm, 0.4 mm, and 0.6 mm, respectively.

  As shown in Table 1, the magnetic sheet 58 used in Samples 06 to 09 has a two-layer structure having a magnetic layer A 58a and a magnetic layer B 58b. The magnetic layer A58a of the sample 06 and the sample 07 is a ferrite layer composed of a ferrite sintered body, and has a thickness of 0.1 mm and 0.2 mm, respectively. The magnetic layer B58b of Sample 06 and Sample 07 is a magnetic metal layer made of a non-oxidized metal and has a thickness of 0.3 mm. The magnetic sheets 58 of Sample 08 and Sample 09 have a configuration in which the magnetic layer A 58a and the magnetic layer B 58b are replaced with respect to the magnetic sheets 58 of Sample 06 and Sample 07.

  As shown in Table 1, the magnetic sheet 58 used in Sample 10 and Sample 11 has a three-layer structure including a magnetic layer A 58a, a magnetic layer B 58b, and a magnetic layer C 58c. The magnetic layer A 58a and the magnetic layer B 58b of Sample 10 and Sample 11 are the same as the magnetic layer A 58a and the magnetic layer B 58b of Sample 06 and Sample 07. Therefore, the magnetic sheet 58 used in the samples 10 and 11 is obtained by adding the magnetic layer C58c to the magnetic sheets 58 of the samples 06 and 07. The magnetic layer C58c of the sample 10 and the sample 11 is a ferrite layer made of a ferrite sintered body and has a thickness of 0.1 mm.

The non-oxidized magnetic metal constituting the magnetic layer A of sample 02, sample 08 and sample 09 and the magnetic layer B of sample 06, sample 07, sample 10 and sample 11 includes initial permeability μi = 800, saturation magnetic flux. A material having a density Bs = 1.3 T and a% conductivity of about 17% was used. In addition, as the ferrite sintered bodies constituting the magnetic layer A of sample 03 to sample 07, sample 10 and sample 11, the magnetic layer B of sample 08 and sample 09, and the magnetic layer C of sample 10 and sample 11, A magnetic flux having a magnetic permeability μi = 200, a saturation magnetic flux density Bs = 0.38T, and a% conductivity of about 1 × 10 ⁻¹¹ % was used.

For the secondary coil unit 50 according to the inductance measurement samples 01 to 11, the inductance of the secondary coil 52 was measured. In order to measure the inductance Ls when the secondary coil unit 50 is mounted on a mobile phone or the like, the inductance of the primary coil unit 20 and the battery 14 is set to 2 as shown in FIG. It carried out by arranging around the secondary coil unit 50.

  The primary coil unit 20 shown in FIG. 5A is the same as that described in FIG. 2 and the like with respect to the first embodiment, and a magnet 26 is arranged in the center of the primary coil 22. As the magnet 26, a magnet made of magnesium alone was used, and a magnetic flux density B at a position 2 mm away from the surface of the magnet 26 was 102 mT (the periphery of the magnet 26 was air). In addition, the primary side coil unit 20 was arrange | positioned with the space | interval of 4 mm with respect to the secondary side coil unit 50. FIG.

  As the battery 14 shown in FIG. 5B, a Li secondary battery whose main body is housed in an aluminum case was used. The battery 14 was disposed so as to be in contact with the outer surface of the magnetic sheet 58 of the secondary coil unit 50 (the surface opposite to the surface with which the secondary coil 52 contacts).

  In addition, in the inductance measurement of each sample, in addition to the inductance Ls at the time of mounting, the inductance Lo of reference A and the inductance Lo2 of reference B were measured for the purpose of cause analysis. The inductance Lo of the reference A is the inductance of the secondary coil 52 measured in the state of the secondary coil unit 50 according to each sample as shown in FIG. On the other hand, the inductance Lo2 of Reference B was measured in a state where only the primary coil unit 20 was arranged with respect to the secondary coil unit 50 according to each sample, as shown in FIG. 5 (c). This is the inductance of the secondary coil 52. The inductance was measured using an LCR meter (product model number: Agilent 4284A). Table 1 shows the inductance measurement results for each sample.

Evaluation of Each Sample The graph shown in FIG. 6 represents the inductance Lo of Reference A and the inductance Ls at the time of mounting for Sample 01 to Sample 03 in Table 1. In the sample 01, the inductance Ls at the time of mounting was greatly reduced with respect to the inductance Lo of Reference A, which is the inductance of the unit alone. This is because the secondary coil unit 50 according to the sample 01 does not have the magnetic sheet 58, and therefore the magnetic flux that does not pass through the secondary coil 52 increases due to the influence of the battery 14 in the mounted state shown in FIG. It is considered that the inductance of the secondary coil 52 has decreased.

  In the sample 02, the inductance Lo of the reference A that is the inductance of the unit unit is lower than that of the sample 01 that does not have the magnetic sheet 38. This is considered because the inductance of the secondary coil 52 is reduced due to the eddy current loss in the magnetic sheet 58 because the magnetic sheet 58 of the sample 02 is configured only by the magnetic metal layer. In Sample 02, the inductance Ls at the time of mounting is almost the same as the inductance of the unit alone, and it can be seen that the leakage magnetic flux in the mounting state shown in FIG. This is considered because the saturation magnetic flux density of the magnetic metal layer constituting the magnetic sheet 58 is large. In addition, if the magnetic sheet 58 is composed only of the magnetic metal layer, it is estimated that it is difficult to improve the inductance even if the thickness of the magnetic sheet 58 is increased.

  In the sample 03, the inductance Lo of the reference A, which is the inductance of the single unit, is significantly improved compared to the sample 01 that does not have the magnetic sheet 58. This is considered to be because the magnetic sheet 58 of the sample 02 is composed only of the ferrite layer, so that the eddy current loss is small as in the sample 02 and the magnetic leakage prevention effect by the magnetic sheet 58 is obtained. It is done.

  However, in the sample 03, the inductance Ls at the time of mounting was greatly reduced with respect to the inductance Lo of the reference A, which is the inductance of the unit alone. When the magnet 26, the battery 14, and the like are arranged around the secondary coil unit 50 as in the mounted state shown in FIG. 5A, in the sample 03, the magnetic sheet 58 generates a magnetic flux as when the unit is a single unit. It is thought that it was not possible to communicate. This is because the magnetic sheet 58 of the sample 03 is composed of a ferrite layer with a low saturation magnetic flux density, and the thickness is as thin as 0.3 mm, so that magnetic saturation is likely. Therefore, the magnetic sheet 58 of the sample 03 is likely to be magnetically saturated by the magnetism of the magnet 26, which leads to leakage magnetic flux to peripheral members such as the battery 14, and as a result, the inductance of the secondary coil 52 is considered to be reduced. It is done.

  Note that the sample 01 and the sample 03 in which the inductance Ls at the time of mounting is significantly lower than the inductance Lo of the reference A is problematic because it may cause the battery 14 and the like to generate heat due to leakage magnetic flux. That is, it is considered that a part of the leakage magnetic flux in the sample 01 and the sample 03 is changed to heat in the aluminum case of the battery 14 by the principle of IH (induction heating). Therefore, it is desirable to avoid the magnetic saturation of the magnetic sheet 58 as seen in the sample 01 and the sample 03 from the viewpoint of preventing heat generation of the peripheral members.

  FIG. 7 shows the inductance Lo of Reference A, the inductance Lo2 of Reference B, and the inductance Ls at the time of mounting regarding Sample 03 to Sample 05 in Table 1. Samples 03 to 05 are obtained by gradually increasing the thickness of the magnetic sheet 58 composed of only the ferrite layer to 0.3 mm, 0.4 mm, and 0.6 mm.

  As shown in Table 1, the measurement results of the sample 03 and the sample 04 have the same tendency, and the inductance Lo2 of the reference B (primary coil unit 20) with respect to the inductance Lo of the reference A (unit alone). Yes) is decreasing. This is because the magnetic sheet 58 tends to become magnetically saturated due to the influence of the magnet 26 of the primary coil unit 20, and the AC magnetic flux cannot be concentrated as the magnetic sheet 58 is a single unit, and the inductance of the secondary coil 52 is reduced. It is thought that it decreased.

  In addition, in the sample 03 and the sample 04, the inductance Ls at the time of mounting is greatly reduced with respect to the inductance Lo of the reference A, and the inductance reduction due to the influence of the arrangement of the battery 14 is also remarkable. However, as is clear from the comparison of Sample 03 to Sample 05, even if the magnetic sheet 58 is composed only of a ferrite layer, increasing the thickness of the magnetic sheet 58 can improve the inductance Ls during mounting. Is possible.

  That is, in the sample 05 in which the thickness of the magnetic sheet 58 is 0.6 mm, the inductance Ls at the time of mounting is 50 μH or more, and the inductance of the secondary coil 52 alone (the inductance Lo of the reference A of the sample 01) is about 40 μH. In contrast, a significant improvement is observed. The sample 05 absorbs the influence of the magnetic flux of the magnet 26 because the magnetic sheet 58 is thick, reduces the generation of leakage magnetic flux due to the magnetic saturation observed in the sample 03 and the like, and applies the magnetic flux to the secondary coil 52. It was thought that the inductance was improved because it could be concentrated. Therefore, the secondary coil unit 50 according to the sample 05 can efficiently supply power even when mounted on a mobile phone or the like. Thus, it is understood that if the magnetic sheet 58 is configured only by the ferrite layer, the thickness of the magnetic sheet 58 must be increased in order to perform efficient power feeding.

  FIG. 8 shows the inductance Lo of Reference A and the inductance Ls at the time of mounting of Sample 02 and Sample 04 to Sample 09. As shown in Table 1, in the magnetic sheet 58 of sample 06, the magnetic layer A 58a disposed in the vicinity of the secondary coil 52 is a ferrite layer having a thickness of 0.1 mm, and the outer magnetic layer B 58b is formed with a thickness of 0. .3 mm magnetic metal layer. Comparing sample 06 and sample 02, it can be seen that the inductance of the secondary coil 52 is significantly improved by sandwiching the ferrite layer between the magnetic metal layer and the secondary coil 52.

  Further, the inductance Ls at the time of mounting of the sample 06 is higher than the inductance Ls at the time of mounting of the sample 04 in which the magnetic sheet 58 is configured only by the ferrite layer and the thickness D is the same (0.4 mm). Yes. Further, in sample 07 in which the thickness of the ferrite layer (magnetic layer A 58a) is increased to 0.2 mm and the thickness D of the magnetic sheet 58 is 0.5 mm, the inductance Ls at the time of mounting is further improved. I understand. That is, in the sample 07, the magnetic sheet 58 is composed only of the ferrite layer, and the inductance Ls at the time of mounting is large even when compared with the sample 05 in which the thickness D is larger (0.6 mm).

  As described above, the magnetic sheet 58 has a two-layer structure in which the secondary coil 52 side (magnetic layer A 58a) is a ferrite layer and the opposite side (magnetic layer B 58b) is a magnetic metal layer. It was confirmed that the magnetic sheet 58 can be made thinner than the case of the layer, and the inductance Ls at the time of mounting can be improved.

  The sample 08 and the sample 09 shown in FIG. 8 use the magnetic sheet 58 in which the arrangement of the ferrite layer and the magnetic metal layer is reversed with respect to the sample 06 and the sample 07. That is, the magnetic sheets 58 of Sample 08 and Sample 09 have a two-layer structure in which the secondary coil 52 side (magnetic layer A 58a) is a magnetic metal layer and the opposite side (magnetic layer B 58b) is a ferrite layer.

  Samples 08 and 09 show almost no change or improvement in the inductances Lo and Ls as compared with sample 02 in which the magnetic sheet 58 is only a magnetic metal layer. Thus, even if the magnetic sheet 58 has a two-layer structure, when the secondary coil 52 side (magnetic layer A 58a) is a magnetic metal layer and the opposite side (magnetic layer B 58b) is a ferrite layer, the secondary coil The effect of improving the inductance of 52 could not be obtained. The magnetic metal layers in Sample 08 and Sample 09 are arranged close to the secondary coil 52 and have high electrical conductivity. Since many eddy current losses have occurred here, a ferrite layer is added outside. However, it is thought that the effect which suppresses generation | occurrence | production of the eddy current in a magnetic metal layer was hardly acquired.

  From the results of samples 01 to 09, the magnetic sheet 58 in which the secondary coil 52 side (magnetic layer A 58a) is a ferrite layer and the opposite side (magnetic layer B 58b) is a magnetic metal layer is a secondary coil unit. It has been confirmed that there is a significant effect in reducing the thickness of 50 and improving the transmission efficiency. One cause of this mechanism is that not only the ferrite layer (magnetic layer A 58a) having a low saturation magnetic flux density but also the magnetic metal layer (magnetic layer B 58b) having a high saturation magnetic flux density is combined, so that the magnetic sheet 58 is hardly magnetically saturated. It is thought that.

  Another cause of the mechanism is the arrangement of the ferrite layer and the magnetic metal layer that can suppress the generation of eddy current loss in the magnetic metal layer while taking advantage of the magnetic metal layer having a high saturation magnetic flux density. Conceivable. That is, in sample 06 and sample 07, since the ferrite layer is arranged on the secondary coil 52 side, the magnetic flux is preferentially transmitted by the ferrite layer (magnetic layer A58a) close to the secondary coil 52, and the magnetic metal layer ( The magnetic flux transmitted through the magnetic layer B58b) is suppressed. Thereby, it is considered that the secondary coil unit 50 according to the sample 06 and the sample 07 can suppress the occurrence of loss due to the eddy current and prevent the inductance of the secondary coil 52 from being reduced due to the eddy current loss.

  FIG. 9 shows the inductance Ls when the sample 05, the sample 10, and the sample 11 are mounted. As shown in Table 1, the magnetic sheet 58 of the sample 10 has a central magnetic layer B58b as a magnetic metal layer, and a ferrite layer disposed on both sides of the secondary coil 52 and the opposite side of the magnetic metal layer. It is. The thickness D of the magnetic sheet 58 used in the sample 10 is 0.5 mm. The inductance Ls when the sample 10 is mounted is substantially the same as that of the sample 05 in which the magnetic sheet 58 is composed only of the ferrite layer and the thickness D is larger (0.6 mm).

  Further, in the sample 11 in which the thickness of the ferrite layer (magnetic layer A58a) on the secondary coil 52 side is increased to 0.2 mm and the thickness D of the magnetic sheet 58 is 0.6 mm, the inductance Ls during mounting is further increased. You can see that it has improved. That is, the sample 11 has a larger inductance Ls at the time of mounting than the sample 05 in which the magnetic sheet 58 is configured only by the ferrite layer and the thickness D is the same (0.6 mm).

  Thus, the magnetic sheet 58 has a three-layer structure in which the secondary coil 52 side (magnetic layer A 58a) is a ferrite layer, the central portion (magnetic layer B 58b) is a magnetic metal layer, and the opposite side (magnetic layer C 58c) is a ferrite layer. As a result, it was confirmed that the inductance of the secondary coil 52 can be improved.

Sample 12 to Sample 18
Next, seven types of secondary coil units 50 according to Sample 12 to Sample 18 were prepared, and the inductance was measured for each sample. The secondary coil unit 50 according to Samples 12 to 18 is the same as the secondary coil unit 50 according to Sample 02 and Samples 06 to 11 except that the non-oxidized magnetic metal used as the magnetic metal layer is different. . That is, in the magnetic sheet 58 according to the samples 12 to 18, as the non-oxidized magnetic metal constituting the magnetic metal layer, the initial permeability μi = 500, the saturation magnetic flux density Bs = 1.4T, and the% conductivity is 4%. Was used.

  In addition, for the secondary coil unit 50 according to the samples 12 to 18, similarly to the samples 01 to 11, the inductance Lo of the reference A, the inductance Lo2 of the reference B, and the inductance Ls at the time of mounting of the secondary coil 52 are set. It was measured. Table 2 shows data of the magnetic sheets 58 according to the samples 12 to 18 together with the inductance measurement results.

Evaluation of each sample The graph shown in FIG. 10 shows the inductance Ls at the time of mounting for the samples 12 to 18 in Table 2 together with the inductance Ls at the time of mounting for the sample 04 in Table 1. Regarding Sample 12 to Sample 18 using different non-oxidized magnetic metals as the magnetic metal layer, the same results as Sample 01 to Sample 12 described above were obtained.

  That is, as shown in Table 2, in the magnetic sheet 58 of the sample 13, the magnetic layer A 58a disposed in the vicinity of the secondary coil 52 is a ferrite layer having a thickness of 0.1 mm, and the outer magnetic layer B 58b is thick. The magnetic metal layer has a thickness of 0.3 m. Sample 13 has magnetic sheet 58 composed of only a ferrite layer and has a thickness D similar to that of sample 04 (0.4 mm). Sample 12 includes magnetic sheet 58 composed of only a magnetic metal layer. Compared with, the inductance Ls at the time of mounting was improved (FIG. 10).

  Further, in the sample 14 in which the thickness of the ferrite layer (magnetic layer A 58a) is increased to 0.2 mm and the thickness D of the magnetic sheet 58 is 0.5 mm, as in the sample 08 shown in FIG. It can be seen that the inductance Ls is further improved.

  The sample 15 and the sample 16 shown in FIG. 10 use a magnetic sheet 58 in which the arrangement of the ferrite layer and the magnetic metal layer is reversed with respect to the sample 04 and the sample 15. Similarly to the sample 08 and the sample 09 shown in FIG. 8, the sample 15 and the sample 16 hardly change the inductance Ls at the time of mounting compared to the sample 12 in which the magnetic sheet 58 is only the magnetic metal layer. .

  As shown in Table 2, sample 17 and sample 18 shown in FIG. 10 have a central magnetic layer B58b as a magnetic metal layer, and ferrite layers are arranged on the secondary coil 52 side and opposite sides of the magnetic metal layer. The magnetic sheet 58 is used. It can be seen that the sample 17 and the sample 18 can also improve the inductance of the secondary coil 52 as in the case of the sample 10 and the sample 11 shown in FIG.

  From the above results, it is recognized that even when the non-oxidized magnetic metal constituting the magnetic metal layer is changed, the magnetic sheet 58 can be thinned and the inductance Ls at the time of mounting can be improved by the same mechanism.

DESCRIPTION OF SYMBOLS 10 ... Non-contact electric power feeder 14 ... Battery 20 ... Primary side coil unit 22 ... Primary coil 22a ... Primary coil opposing surface 22b ... Primary coil back surface 24 ... Primary coil hole part 26 ... Magnet 28 ... Magnetic body part 30 , 40, 50 ... secondary coil unit 32, 52 ... secondary coil 32a ... secondary coil facing surface 32b ... secondary coil back surface 36 ... adsorbent 38 ... magnetic sheet 38a, 48a ... first magnetic layer 38b, 48b ... Second magnetic layer 48c ... Third magnetic layer 58a ... Magnetic layer A
58b ... Magnetic layer B
58c ... Magnetic layer C

Claims (5)

A flat secondary coil having a facing surface facing the primary coil and a back surface opposite to the facing surface, and a magnetic sheet disposed to cover the back surface of the secondary coil,
The magnetic sheet is disposed between the first magnetic layer adjacent to the secondary coil and the secondary coil with the first magnetic layer interposed therebetween, and has a second saturation magnetic flux density higher than that of the first magnetic layer. A secondary coil unit for non-contact power feeding, comprising: a magnetic layer. The first magnetic layer is a resin magnetic powder mixed layer composed of magnetic powder and a resin connecting the magnetic powder, or a ferrite layer composed of ferrite,
The secondary coil unit for non-contact power feeding according to claim 1, wherein the second magnetic layer is a magnetic metal layer made of a non-oxidized magnetic metal.   3. The secondary coil unit for non-contact power feeding according to claim 1, wherein the first magnetic layer has a lower% conductivity than that of the second magnetic layer. 4.   The magnetic sheet further includes a third magnetic layer that is disposed between the second coil and the first magnetic layer and the second magnetic layer, and is made of the same material as the first magnetic layer. The secondary side coil unit for non-contact electric power feeding according to any one of claims 1 to 3 characterized by things. The secondary coil unit for non-contact power feeding according to any one of claims 1 to 4,
The non-contact electric power feeder which has the primary side coil unit for non-contact electric power feeding which has the said primary coil and the magnet arrange | positioned in the center part of the said primary coil.

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