JP6555198B2 - Coil unit - Google Patents

Description

  The present invention relates to a coil unit, and more particularly to a coil unit used in a non-contact charging system.

  Conventionally, various types of coil units used in contactless charging systems have been proposed. For example, a power transmission device described in JP-A-2006-73018 includes a power transmission coil side coil unit, and a power reception device includes a power reception side coil unit.

  The power transmission side coil unit includes a ferrite plate formed in a plate shape and a hollow power transmission coil disposed on the upper surface of the ferrite plate. The power reception side coil unit also includes a ferrite plate and a hollow power reception coil. Including.

JP, 2006-73018, A

  When power is transmitted from the power transmission device described in JP-A-2006-073018 to the power reception device, power is supplied to the power transmission coil, and magnetic flux is formed around the power transmission coil. This magnetic flux passes, for example, from the hollow portion of the power transmission coil through the ferrite plate and from the outer peripheral edge side of the ferrite plate toward the power receiving side coil unit.

  Then, the magnetic flux from the power transmission coil enters the ferrite plate from the outer peripheral edge side of the ferrite plate of the power receiving side coil unit. Thereafter, the magnetic flux passes through the ferrite plate and exits from the hollow portion of the power receiving coil toward the power transmission device. In this way, the magnetic flux from the power transmission coil is linked to the power reception coil.

  When the magnetic flux is linked to the power receiving coil, a power receiving current flows in the power receiving coil, and the power receiving coil receives power. Then, a magnetic flux is formed around the receiving coil by the receiving current. And the magnetic flux from a receiving coil also passes the same magnetic path as the magnetic flux from a power transmission coil.

  Thus, when a magnetic flux flows around the power transmission coil and the power receiving coil, a large amount of magnetic flux flows through a magnetic flux path having a short path length. As a result, a large amount of magnetic flux flows in the magnetic flux path passing through the vicinity of the power transmission coil and the power reception coil, and the magnetic flux density of the facing portion facing the power transmission coil or the power reception coil is increased in the ferrite plate of each coil unit.

  When the magnetic flux density at the facing portion increases, the amount of heat generated at the facing portion increases, loss increases, and power reception efficiency decreases. And if the electric power supplied to a power transmission coil is increased in order to maintain the received electric power which a power receiving apparatus receives, the temperature rise of the opposing part of a ferrite plate will be caused further.

  Thus, there is a problem that the temperature of the facing portion of the ferrite plate is likely to be higher than that of the other portion of the ferrite plate.

  The coil unit described in the present specification has been made in view of the above problems, and its purpose is to suppress the temperature of the facing portion of the ferrite plate facing the coil from becoming high. It is.

  The coil unit described in the present specification is disposed on the first main surface, and extends in the thickness direction, with a plate-like ferrite plate including a first main surface and a second main surface arranged in the thickness direction. And a hollow coil formed so as to surround the winding axis. A thick part is formed in at least a part of the facing part facing the coil in the ferrite plate, and the thick part is thicker than the part adjacent to the thick part.

  In the above coil unit, when a current flows through the coil, a magnetic flux is generated around the coil. And the magnetic flux density of the magnetic flux which passes through the opposing part which opposes a coil among ferrite plates becomes high. On the other hand, the thick part is formed in the opposing part, and it can suppress that the magnetic flux density in an opposing part becomes high, and it can suppress that a big loss arises in an opposing part.

  According to the coil unit described in this specification, it can suppress that the temperature of the opposing part which opposes a coil among ferrite plates becomes high.

1 is a schematic diagram schematically showing a non-contact charging system 1. FIG. 1 is an electric circuit diagram schematically showing a contactless charging system 1. FIG. 2 is an exploded perspective view showing a power transmission device 3. FIG. 3 is a cross-sectional view showing a part of the power transmission device 3. FIG. It is a top view when the power transmission coil 12 and the ferrite plate 15 are planarly viewed from the observation position P1 on the winding axis O1 shown in FIG. It is a top view which shows the structure of the corner | angular piece 33 and its periphery. It is a perspective view which shows the side piece 34 and the corner | angular piece 33. FIG. 4 is a schematic diagram schematically showing a state in which power is transmitted from the power transmission device 3 to the power reception device 4. FIG. 2 is a perspective view showing a part of a ferrite plate 15 and a power transmission coil 12. FIG. It is a figure which shows a part of cross section when it cross-sectional views by the XX line shown in FIG. It is a top view which shows magnetic flux density distribution when the ferrite plate 15A which made the thickness of each division | segmentation ferrite plate 35A-35E the same thickness is employ | adopted. It is the enlarged view to which a part of FIG. 11 was expanded. It is a graph which shows magnetic flux distribution of the division | segmentation ferrite plate 35C. It is a perspective view which shows the modification of the split ferrite plate 35C, and is a perspective view when the split ferrite plate 35C is viewed from below.

  The coil unit according to the embodiment will be described with reference to FIGS. Note that, among the configurations illustrated in FIGS. 1 to 14, the same configuration or substantially the same configuration may be denoted by the same reference numeral and redundant description may be omitted.

  FIG. 1 is a schematic diagram schematically showing the contactless charging system 1, and FIG. 2 is an electric circuit diagram schematically showing the contactless charging system 1. As shown in FIGS. 1 and 2, the non-contact charging system 1 includes a vehicle 2 and a power transmission device 3.

  The vehicle 2 includes a power receiving device 4 that receives power from the power transmitting device 3 in a contactless manner, and a battery 7 that stores the power received by the power receiving device 4. The power receiving device 4 includes a coil unit 5 and a rectifier 6 that converts AC power received by the coil unit 5 into DC power and supplies the DC power to the battery 7. The coil unit 5 includes a power receiving coil 8 and a capacitor 9, and an LC resonator is formed by the power receiving coil 8 and the capacitor 9.

  The power transmission device 3 includes a converter 11 and a coil unit 14 connected to the converter 11. The converter 11 is connected to the power supply 10, and the converter 11 adjusts the frequency and voltage of the AC power supplied from the power supply 10 and supplies it to the coil unit 14.

  The coil unit 14 includes a power transmission coil 12 and a capacitor 13, and an LC resonator is formed by the power transmission coil 12 and the capacitor 13.

  An alternating current supplied from the converter 11 flows through the power transmission coil 12, and an electromagnetic field is formed around the power transmission coil 12. When this electromagnetic field reaches the power receiving coil 8, the coil unit 5 receives power.

  FIG. 3 is an exploded perspective view showing the power transmission device 3. As shown in FIG. 3, the power transmission device 3 includes a coil unit 5, a housing case 20 that houses the coil unit 5, a converter 11 provided in the housing case 20, a capacitor 13, and a support plate 21.

  The housing case 20 includes a metal case main body 22 that opens upward, and a resin lid 23 that is provided so as to cover the opening of the case main body 22.

  A plurality of support walls 24 are formed in the case main body 22, and the case main body 22 is partitioned into a plurality of storage chambers by the plurality of support walls 24. The converter 11 and the capacitor 13 are accommodated in each accommodation chamber.

  The coil unit 5 includes a ferrite plate 15 formed in a plate shape, a power transmission coil 12, and a capacitor 13.

  Ferrite plate 15 includes an upper surface 16 and a lower surface 17 arranged in the thickness direction TD. The power transmission coil 12 is disposed on the upper surface 16 of the ferrite plate 15. The power transmission coil 12 is formed so as to surround the winding axis O1 extending in the thickness direction TD1.

  The support plate 21 is disposed on the lower surface 17 side of the ferrite plate 15, and the support plate 21 is formed of a metal material such as aluminum. The support plate 21 is disposed on the support wall 24 and supports the ferrite plate 15 disposed on the upper surface of the support plate 21.

  FIG. 4 is a cross-sectional view showing a part of the power transmission device 3. As shown in FIG. 4, the power transmission device 3 includes a bobbin 18 disposed on the upper surface of the ferrite plate 15. The bobbin 18 is formed of an insulating material such as resin, and a groove portion 19 into which the power transmission coil 12 is fitted is formed on the upper surface of the bobbin 18.

  FIG. 5 is a plan view of the power transmission coil 12 and the ferrite plate 15 as viewed in plan from the observation position P1 on the winding axis O1 shown in FIG.

  As shown in FIG. 5, the power transmission coil 12 has a polygonal shape with curved corners, and in the example shown in FIG. 5, it has a rectangular shape.

  The power transmission coil 12 includes a plurality of corner portions 30 formed at intervals, a pair of straight portions 31A, and a pair of straight portions 31B. Each corner 30 is bent in a curved shape. Each linear part 31A, 31B connects the adjacent corner | angular part 30, and the length of 31 A of linear parts is longer than the length of the linear part 31B.

  The power transmission coil 12 is formed in a hollow shape, and an opening 32 is formed in the center of the power transmission coil 12.

  Ferrite plate 15 includes a plurality of corner pieces 33 and a plurality of side pieces 34 provided at intervals. Each corner piece 33 is disposed below the corner portion 30 of the power transmission coil 12, and each side piece 34 is disposed below the straight portion 31 </ b> A.

  A notch 36 is formed by the corner pieces 33 adjacent to each other in the direction in which the straight portion 31B extends. The notch 36 is formed so as to extend from the outside of the power transmission coil 12 toward the opening 32, and the width W <b> 1 of the notch 36 is formed so as to decrease from the outside of the power transmission coil 12 toward the opening 32. Has been.

  A side piece 34 is disposed between corner pieces 33 adjacent to each other in the direction in which the straight line portion 31 </ b> A extends, and a notch 37 is also formed between the side piece 34 and the corner piece 33. The notch 37 is also formed so as to extend from the outside of the power transmission coil 12 toward the opening 32. The width W <b> 2 of the notch 37 is also formed so as to decrease from the outside of the power transmission coil 12 toward the opening 32.

  The side piece 34 is disposed so as to be orthogonal to the straight portion 31A. One end of the side piece 34 is located in the opening 32, and the other end of the opening 32 is located outside the power transmission coil 12. The side piece 34 includes two divided ferrite plates 35A and 35B, and the gap between the divided ferrite plates 35A and 35B also extends in a direction perpendicular to the straight portion 31A.

  FIG. 6 is a plan view showing a configuration of the corner piece 33 and its surroundings. In FIG. 6, the tangent line L <b> 1 is a tangent line at the vertex P <b> 2 of the corner portion 30.

  One end of the corner piece 33 is located in the opening 32, and the other end is located outside the power transmission coil 12.

  The corner piece 33 includes a divided ferrite plate 35C arranged below the apex P2 and divided ferrite plates 35D and 35E arranged so as to sandwich the divided ferrite plate 35C.

  Here, the divided ferrite plate 35C is arranged so that the direction from one end to the other end of the divided ferrite plate 35C is orthogonal to the tangent L1. The divided ferrite plates 35D and 35E are also arranged in the same manner as the divided ferrite plate 35C.

  FIG. 7 is a perspective view showing the side piece 34 and the corner piece 33. The part shown by the oblique line in the figure shows the part where each divided ferrite plate faces the power transmission coil 12.

  Specifically, the facing portion 45 </ b> A is a portion where the divided ferrite plate 35 </ b> A faces the power transmission coil 12. Similarly, the facing portions 45B, 45C, 45D, and 45E are portions where the divided ferrite plates 35B, 35C, 35D, and 35E face the power transmission coil 12. Here, the thickness T1 of the divided ferrite plate 35C is thicker than the thicknesses T2, T3, T4, and T5 of the divided ferrite plates 35A, 35B, 35D, and 35E.

  For this reason, the opposing part 45C which is a part of opposing part 45A-45E which opposes the power transmission coil 12 among the ferrite plates 15 is formed so that it may become thick. In the example shown in FIG. 7, the divided ferrite plate 35C is a thick portion, and the other divided ferrite plates 35A, 35B, 35D, and 35E are adjacent portions adjacent to the thick portion, and the thickness of the divided ferrite plate 35C. Is thicker than the adjacent part.

  FIG. 8 is a schematic diagram schematically illustrating a state in which power is transmitted from the power transmission device 3 to the power reception device 4. In FIG. 8, an alternating current flows through the power transmission coil 12 of the coil unit 14, a magnetic flux MF is generated around the power transmission coil 12, and the magnetic flux MF passes through various magnetic flux paths.

  In the example shown in FIG. 8, the magnetic flux path MP1 is an interlinkage path passing through the split ferrite plate 35E and passing through the power receiving coil 8 and the power transmitting coil 12. Similarly, the magnetic flux path MP2 is an interlinkage path through which both the power receiving coil 8 and the power transmitting coil 12 pass through the divided ferrite plate 35A.

  On the other hand, the magnetic flux path MP3 is a path that passes through the divided ferrite plate 35E, passes only around the power transmission coil 12, and does not pass through the power reception coil 8. The magnetic flux path MP4 also passes through the divided ferrite plate 35A, passes only around the power transmission coil 12, and does not pass through the power reception coil 8. The path lengths of the magnetic flux paths MP3 and MP4 are shorter than the path lengths of the magnetic flux paths MP1 and MP2, and the magnetic resistances of the magnetic flux paths MP3 and MP4 are lower than the magnetic resistances of the magnetic flux paths MP1 and MP. Therefore, the magnetic flux MF passing through the magnetic flux paths MP3 and MP4 is relatively large.

  On the other hand, a receiving current flows through the receiving coil 8 by the magnetic flux passing through the magnetic flux paths MP1 and MP2.

  FIG. 9 is a perspective view showing a part of the ferrite plate 15 and the power transmission coil 12. In FIG. 9, a magnetic flux path MP5 is a path that passes through the divided ferrite plate 35D, the periphery of the power transmission coil 12, and the notch 36. Here, when the magnetic flux MF passes through the notch 36, the magnetic flux MF flows in the air. The magnetoresistance of air is much higher than that of ferrite.

  On the other hand, since the magnetic flux path MP3 or the like does not pass through the notch 36, the magnetic resistance of the magnetic flux path MP3 is lower than the magnetic resistance of the magnetic flux path MP5. As a result, the amount of magnetic flux passing through the magnetic flux path MP3 is larger than the amount of magnetic flux passing through the magnetic flux path MP5. Similarly, the magnetic flux path MP6 is a path that passes through the notch 37, and has a higher magnetic resistance than the magnetic flux path MP3. For this reason, a large amount of magnetic flux flows through the magnetic flux path MP3.

  FIG. 10 shows a part of a cross section when viewed in cross section along line XX shown in FIG. As shown in FIG. 10, the magnetic flux density in the facing portion 45C of the divided ferrite plate 35C is larger than the magnetic flux density in the portion adjacent to the facing portion 45C in the divided ferrite plate 35C. In particular, it can be seen that the magnetic flux density increases as it approaches the center of the divided ferrite plate 35C.

  FIG. 11 is a plan view showing a magnetic flux density distribution when a ferrite plate 15A having the same thickness for each of the divided ferrite plates 35A to 35E is employed. FIG. 12 is an enlarged view of a part of FIG. FIG. In FIGS. 11 and 12, the magnetic flux density distribution increases from the region R1 toward the region R6.

  As shown in FIGS. 11 and 12, in the ferrite plate 15A, it can be seen that the magnetic flux density in the central portion of each of the divided ferrite plates 35A to 35E is high. Thus, the part with a high magnetic flux density corresponds with the part which opposes the power transmission coil 12 in each divided ferrite plate 35A-35E. In particular, it can be seen that the magnetic flux density in the central portion of the divided ferrite plate 35C and the periphery thereof is the highest. The central portion of the divided ferrite plate 35 </ b> C and its periphery coincide with the facing portion 45 </ b> C that faces the power transmission coil 12.

  As described above, when the thickness of the divided ferrite plate 35C and the thickness of the other divided ferrite plates 35A, 35B, 35D, and 35E are the same, a large loss (heat generation) occurs in the facing portion 45C of the divided ferrite plate 35C. I understand that.

  On the other hand, in the coil unit 14 according to the present embodiment, as shown in FIG. 7, the thickness T1 of the divided ferrite plate 35C is thicker than the other divided ferrite plates 35A, 35B, 35D, and 35E. For this reason, the sectional area of the divided ferrite plate 35C (the sectional area in the direction perpendicular to the direction in which the divided ferrite plate 35C extends long) is wider than the sectional area of the other divided ferrite plates 35A, 35B, 35D, and 35E. Therefore, even if a large amount of magnetic flux MF flows through the facing portion 45C of the divided ferrite plate 35C, it is possible to suppress an excessive increase in the magnetic flux density of the facing portion 45C. Along with this, it is possible to suppress an increase in temperature also in the facing portion 45C.

  FIG. 13 is a graph showing the magnetic flux distribution of the divided ferrite plate 35C. Specifically, the broken line graph L11 shows the magnetic flux density from the end P3 to the end P3 to the end P4 shown in FIG. 12 in the ferrite plate 15A as a comparative example. A solid line graph L10 indicates the magnetic flux density at the same position in the ferrite plate 15 according to the present embodiment. In addition, a vertical axis | shaft shows magnetic flux density and a horizontal axis shows a position. As is apparent from the graph shown in FIG. 13, the magnetic flux density of the facing portion 45C of the ferrite plate 15 according to the present embodiment is lower than the magnetic flux density of the facing portion 45C of the ferrite plate 15A of the comparative example. .

  Thus, according to the coil unit 14 which concerns on this Embodiment, it can suppress that the part from which magnetic flux density becomes high arises, and can suppress the temperature rise of the coil unit 14. FIG. Further, the thickness of some of the divided ferrite plates 35C is increased, and the manufacturing cost is reduced as compared with the case of increasing the thickness of all the divided ferrite plates 35A to 35E.

  Next, a modified example of the ferrite plate 15 will be described with reference to FIG. In the above embodiment, the entire divided ferrite plate 35C is formed to be thick, but the thickness of the portion where the facing portion 45 is located may be increased. FIG. 14 is a perspective view showing a modified example of the divided ferrite plate 35C, and is a perspective view when the divided ferrite plate 35C is viewed from below. In FIG. 14, the hatched portion indicates the facing portion 45C.

  As shown in FIG. 14, the divided ferrite plate 35 </ b> C includes a thick portion 42 and adjacent portions 43 and 44 adjacent to the thick portion 42. The thick portion 42 is located in the facing portion 45 that faces the power transmission coil 12. The adjacent portion 43 is located inside the power transmission coil 12 relative to the thick portion 42, and the adjacent portion 44 is located outside the power transmission coil 12. The thickness T6 of the thick portion 42 is thicker than the thicknesses T7 and T8 of the adjacent portions 43 and 44.

  The split ferrite plate 35C includes an upper surface 40 and a lower surface 41. The thick part 42 is formed on the lower surface 41, and the thick part 42 is formed so as to protrude downward. The upper surface 40 is formed in a flat surface shape. The divided ferrite plate 35 </ b> C includes a side surface 46 and a side surface 47 arranged in the width direction WD, and the thick portion 42 is formed so as to reach the side surface 47 from the side surface 46.

  For this reason, the cross-sectional area of the facing portion 45C is larger than the cross-sectional areas of the adjacent portion 44 and the adjacent portion 43, and even if a large amount of magnetic flux MF passes through the facing portion 45C, the magnetic flux density is increased in the facing portion 45C. Can be suppressed. A one-dot chain line graph L12 in FIG. 13 is a graph showing the magnetic flux density of the divided ferrite plate 35C according to the modification. As shown in this alternate long and short dash line graph L12, according to the divided ferrite plate 35C according to the modification, the magnetic flux density can be equalized throughout. Further, even in the divided ferrite plate 35C according to the modification, it is possible to suppress the occurrence of excessive loss and heat generation locally.

  Further, in the above modification, the opposing portion 45C of the divided ferrite plate 35C is thickened, but not only the opposing portion 45C but also the other divided ferrite plates 35A, 35B, 35D, and 35E shown in FIG. The portions 45A, 45B, 45D, and 45E may be similarly thickened.

  In the above-described embodiment and the like, the coil unit 14 of the power transmission device 3 has been mainly described. However, the configurations of the coil unit 14 and the ferrite plate 15 are also applied to the coil unit 5 and the ferrite plate of the power receiving device 4. be able to.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The coil unit described in this specification can be applied to a coil unit of a non-contact charging system.

  DESCRIPTION OF SYMBOLS 1 Contactless charging system, 2 Vehicle, 3 Power transmission apparatus, 4 Power receiving apparatus, 5,14 Coil unit, 6 Rectifier, 7 Battery, 8 Power receiving coil, 9,13 Capacitor, 10 Power supply, 11 Converter, 12 Power transmission coil, 15 , 15A Ferrite plate, 16 upper surface, 17 lower surface, 18 bobbin, 19 groove portion, 20 housing case, 21 support plate, 22 case body, 23 resin lid, 24 support wall, 30 corners, 31A, 31B linear portion, 32 opening , 33 Corner piece, 34 Side piece, 35, 35A, 35B, 35C, 35D, 35E Split ferrite plate, 36, 37 Notch, 42 Thick part, 43, 44 Adjacent part, 45, 45A, 45B, 45C , 45D, 45E Opposite part, 46, 47 side, L1 tangent, MF magnetic flux, MP, MP1, MP2, MP3, MP 4, MP5, MP6 magnetic flux path, O1 winding axis, P1 observation position, P2 apex, P3, P4 end, T1, T2, T3, T4, T5, T6, T7, T8 thickness, TD, TD1 thickness direction , W1, W2 width, WD width direction.

Claims (1)

A plate-like ferrite plate including a first main surface and a second main surface arranged in the thickness direction;
A hollow coil disposed on the first main surface and formed so as to surround a winding axis extending in the thickness direction;
With
The coil includes a plurality of straight portions and corner portions connecting adjacent straight portions,
The ferrite plate includes a corner piece in which the corner portion is disposed, and a side piece in which the linear portion is disposed,
The ferrite plate has a notch formed in a portion located between the corner pieces,
The coil unit , wherein the corner piece is formed with a thick portion extending from an inner peripheral side to an outer peripheral side of the corner portion .

Images