JPWO2016135949A1 - Inductor and wireless power transmission device - Google Patents

Abstract

An inductor and a wireless power transmission device in which stress applied to a magnetic core is suppressed are provided. An inductor according to an embodiment includes a plurality of magnetic cores, one or more cases, a winding, a housing, and a reinforcing portion. The case houses the magnetic core inside. The winding is wound around the case. The housing is formed of the first resin so as to cover the case and the winding. A reinforcement part is formed in at least one part between magnetic body cores. The difference between the inner dimension of the case in the same direction and the dimension of the magnetic core is larger than the amount of change in the dimension of the case in that direction when the housing is formed.

Description

  Embodiments described herein relate generally to an inductor and a wireless power transmission device.

  Conventionally, in order to improve the strength and heat dissipation of an inductor for wireless power transmission, an inductor having a structure in which a magnetic core and a winding are covered with a resin has been used. Such an inductor is manufactured by casting resin so as to cover the magnetic core and the winding. In the conventional inductor, since the magnetic core and the resin are in contact with each other, stress is applied to the magnetic core due to curing shrinkage of the resin that occurs during casting. When stress is applied to the magnetic core, magnetostriction of the magnetic core is inhibited. This caused problems such as a decrease in L value and an increase in core loss.

  In order to suppress the stress applied to the magnetic core, an inductor in which the magnetic core is covered with a buffer material has been proposed. However, this inductor has a problem that stress cannot be sufficiently suppressed when the thickness of the buffer material is insufficient.

JP 2013-55229 A JP 2002-164229 A JP 2010-172084 A

  Provided are an inductor and a wireless power transmission device in which stress applied to a magnetic core is suppressed.

  An inductor according to an embodiment includes a plurality of magnetic cores, one or more cases, a winding, a housing, and a reinforcing portion. The case houses the magnetic core inside. The winding is wound around the case. The housing is formed of the first resin so as to cover the case and the winding. A reinforcement part is formed in at least one part between magnetic body cores. The difference between the inner dimension of the case in the same direction and the dimension of the magnetic core is larger than the amount of change in the dimension of the case in that direction when the housing is formed.

XY plane sectional drawing which shows an example of the inductor which concerns on 1st Embodiment. FIG. 2 is a cross-sectional view of the inductor of FIG. XY plane sectional drawing which shows an example of the inductor which concerns on 1st Embodiment. XY plane sectional drawing which shows an example of the inductor which concerns on 2nd Embodiment. AA line sectional view of the inductor of FIG. The YZ plane sectional view showing an example of the inductor concerning a 3rd embodiment. AA line sectional view of the inductor of FIG. A YZ plane sectional view showing an example of an inductor concerning a 4th embodiment. The schematic diagram which shows an example of the fiber layer which concerns on 5th Embodiment. The schematic diagram which shows an example of the fiber layer which concerns on 5th Embodiment. A YZ plane sectional view showing an example of an inductor concerning a 6th embodiment. A YZ plane sectional view showing an example of an inductor concerning a 6th embodiment. A YZ plane sectional view showing an example of an inductor concerning a 7th embodiment. A YZ plane sectional view showing an example of an inductor concerning an 8th embodiment. A YZ plane sectional view showing an example of an inductor concerning a 9th embodiment. A YZ plane sectional view showing an example of an inductor concerning a 10th embodiment. A YZ plane sectional view showing an example of an inductor concerning a 10th embodiment. XY plane sectional drawing which shows an example of the magnetic body core which concerns on 11th Embodiment. A YZ plane sectional view showing an example of a magnetic core according to an eleventh embodiment. The block diagram which shows an example of the power receiving apparatus which concerns on 12th Embodiment. The block diagram which shows an example of the power transmission apparatus which concerns on 12th Embodiment.

  Embodiments of the present invention will be described below with reference to the drawings.

(First embodiment)
First, the inductor according to the first embodiment will be described with reference to FIGS. FIG. 1 is an XY plane sectional view showing an example of an inductor according to the present embodiment. 2 is a cross-sectional view (YZ plane cross-sectional view) taken along the line AA of FIG. As shown in FIGS. 1 and 2, the inductor according to the present embodiment includes a plurality of magnetic cores 1, a case 2, a winding 3, a housing 4, a buffer material 5, a reinforcing portion 6, Is provided.

  The magnetic core 1 is made of a magnetic material such as ferrite or an electromagnetic steel plate. In the following, the direction in which the magnetic flux generated inside the magnetic core 1 is maximized when a current is passed through the winding 3 is the length direction (the direction of the arrow X in FIG. 1), and the direction perpendicular to the length direction is the width. Direction and height direction. The width direction is the direction of the arrow Y in FIGS. 1 and 2, and the height direction is the direction of the arrow Z in FIG. Further, it is assumed that the length of the magnetic core 1 is l, the width is w, and the height is h.

  The magnetic core 1 is formed so that the vicinity of the winding 3 has a larger cross-sectional area (cross-sectional area of the YZ plane) as viewed from the length direction than the other parts. The vicinity of the winding 3 is a portion of the magnetic core 1 surrounded by the winding 3. A portion near the winding 3 is a portion where the magnetic flux density is maximum in the magnetic core 1. When the cross-sectional area of this portion is increased, the magnetic flux density of the magnetic core 1 can be reduced.

  In general, an inductor having the magnetic core 1 causes a core loss. The core loss is energy loss that occurs in the magnetic core 1. Core loss includes hysteresis loss and eddy current loss. This core loss increases as the magnetic flux density in the magnetic core 1 increases. Therefore, core loss can be reduced by thickening part of the magnetic core 1 and reducing the magnetic flux density of the magnetic core 1.

  Further, the core loss of the inductor can be reduced by making the sum of the cross-sectional areas of the magnetic cores 1 in the vicinity of the winding 3 larger than the sum of the cross-sectional areas of the magnetic cores 1 in other parts. Therefore, as shown in FIG. 3, the inductor may include a plurality of magnetic cores 1 having a constant cross-sectional area viewed from the length direction. Since the magnetic core 1 ′ at the center of the inductor shown in FIG. 3 is disposed only in the vicinity of the winding 3, the total cross-sectional area of the vicinity of the winding 3 is greater than the total cross-sectional area of other portions. It is getting bigger. Also in this case, the core loss of the inductor can be reduced.

  The inductor may include four or more magnetic cores 4. In FIG. 1, the cross-sectional area of the magnetic core 1 is increased by increasing the dimension in the width direction of the vicinity of the winding 3, but the magnetic core 1 is increased by increasing the dimension in the height direction. The cross sectional area may be increased.

  The case 2 houses one or more magnetic cores 1 inside. Since the casing 4 is formed outside the case 2, the casing 4 and the magnetic core 1 are not in contact with each other, and stress or thermal stress due to hardening shrinkage of the casing 4 is directly applied to the magnetic core 1. Absent. Therefore, the stress applied to the magnetic core 1 can be suppressed by providing the case 2.

  Case 2 is formed of an insulating material. As a material of the case 2, for example, a thermosetting resin such as an epoxy resin, a thermoplastic resin such as polypropylene, ABS resin, or polyethylene, and glass are used. In the following, it is assumed that the inner dimension in the length direction of the case 2 is L, the inner dimension in the width direction is W, and the inner dimension in the height direction is H. The inner dimension of the case 2 is a dimension between inner walls of the case 2 in each direction. Note that L, W, and H are internal dimensions of the case 2 when no current flows through the winding 3. The relationship between the inner dimension of the case 2 and the dimension of the magnetic core 1 will be described later.

  In FIG. 1, the inductor includes two cases 2, and each case 2 stores one magnetic core 1. However, the case 2 may store a plurality of magnetic cores 1. For example, as shown in FIG. 1, when the inductor includes two magnetic cores 1, the inductor may include one case 2, and the two magnetic cores 1 may be accommodated in the case 2.

  The winding 3 is wound around the case 2. More specifically, the winding 3 is wound not around each case 2 but around the entire plurality of cases 2. As the winding 3, for example, a copper wire, an aluminum wire, a litz wire, or the like is used. When a current flows through the winding 3, the inductor generates a magnetic field.

  The housing 4 is formed of an insulating first resin so as to cover the case 2 and the winding 3. The housing 4 is formed after the magnetic core 1 is housed inside the case 2 and the winding 3 is wound around the case 2. As a method for forming the housing 4, for example, casting or injection molding is used. Also, a layered manufacturing method using a 3D printer may be used. The first resin is selected according to these manufacturing methods. As the first resin, for example, a thermosetting resin such as an epoxy resin, a thermoplastic resin such as polypropylene, ABS resin, or polyethylene, and glass are used.

  The case 2 described above may be formed of a first resin. Thereby, the adhesive strength between the casing 4 and the case 2 can be improved, and the interface peeling between the casing 4 and the case 2 when vibration or impact is applied to the inductor can be suppressed.

  The case 2 may be formed of a second resin different from the first resin. For example, it is conceivable that the case 2 is formed of a second resin having high strength, and the housing 4 is formed of a first resin having high thermal conductivity. Thereby, the intensity | strength and heat dissipation of an inductor can be improved. In addition, the productivity of the inductor can be improved by forming the housing 4 from the first resin having a low viscosity.

  If the first resin enters the case 2 when forming the housing 4, thermal stress may be applied to the magnetic core 1. For this reason, the case 2 is preferably sealed before the housing 4 is formed so that the first resin does not enter the case 2.

  Further, a resonance capacitance may be built in a part of the housing 4. For example, the capacitance is built in a space 41 generated in a portion where the cross-sectional areas of the two magnetic cores 1 are small. The housing 4 may include a storage unit for incorporating a capacitance, and the capacitance may be mounted after the housing 4 is formed. Moreover, the housing | casing 4 may be formed by casting etc. in the state which arrange | positioned the capacitance in the predetermined position (for example, space 41). In this case, the capacitance is built in simultaneously with the formation of the housing 4.

  The buffer material 5 is provided between the case 2 and the magnetic core 1 so as to cover at least a part of the magnetic core 1. The buffer material 5 fixes the magnetic core 1 inside the case 2 and suppresses stress applied to the magnetic core 1 from the outside.

The buffer material 5 is formed of an insulating or semiconductive material. The semiconductive material here refers to a material having higher electrical conductivity than an insulator and lower electrical conductivity than a conductor. Therefore, the semiconductive material has higher conductivity than the material of the case 2 and the housing 4. Specifically, the semiconductive material is a material having an electric conductivity of 10 ⁻⁶ S / m or more and 10 ⁶ S / m or less. The semiconductive material is, for example, a mixture of an insulator and a conductor such as carbon.

  As a material of the buffer material 5, for example, a foamed resin, a rubber resin, a gel resin, a nonwoven fabric, or the like is used. Also, synthetic rubber such as acrylic rubber or silicon rubber may be used. When the buffer material 5 is formed of a semiconductive material, the concentration of the electric field can be relaxed, so that partial discharge between the magnetic core 1 and the winding 3 can be suppressed.

  The buffer material 5 is preferably formed of a material having a lower elastic modulus than that of the first resin in order to buffer stress due to curing shrinkage of the housing 4. Moreover, in order to buffer the stress due to the thermal contraction of the case 2, it is preferably formed of a material having a lower elastic modulus than that of the case 2. Furthermore, the buffer material 5 is preferably provided so as to cover the entire magnetic core 1 as shown in FIGS. 1 and 2 in order to improve the heat dissipation from the magnetic core 1.

  The reinforcing portion 6 is formed between the magnetic cores 1, reinforces the strength of the inductor, and mainly supports the load in the height direction. Since the inner dimension of the case 2 is larger than the outer dimension of the magnetic core 1, the load cannot be supported by the magnetic core 1 when a load is applied to the inductor without the reinforcing portion 6. In view of this, the magnetic core 1 is divided, and a reinforcing portion 6 is provided to support a load at a portion between the divided magnetic cores 1. In FIG. 1, the reinforcing portion 6 is formed by a side surface of the case 2 positioned between two magnetic cores 1 and a housing 4 between the two cases 2.

  As described above, the magnetic core 1 is at least partially covered with the buffer material 5. Although the stress applied to the magnetic core 1 is suppressed by such a stress buffer structure, the load resistance of the portion where the magnetic core 1 is disposed is reduced. Therefore, in the present embodiment, a plurality of magnetic cores 1 are provided, and the reinforcing portions 6 are formed between the magnetic cores 1 to improve the load resistance of the inductor.

  With such a configuration, the inductor according to the present embodiment can be used for applications that require high load resistance. Such applications include, for example, inductors for power transmission for electric vehicles that are assumed to be stepped on by vehicles.

  In order to increase the load resistance of the inductor, the reinforcing portion 6 may be formed of a resin having a higher compressive strength than the first resin, or a fiber reinforced plastic (FRP) using a fiber such as a glass cloth. It may be formed. In addition, when the case 2 houses a plurality of magnetic cores 1, reinforcing portions 6 may be formed between the magnetic cores 1 in the case 2.

  Here, the relationship between the internal dimension of case 2 and the dimension of the magnetic body core 1 is demonstrated. In the magnetic core 1 and the case 2, the minimum value of the difference between the inner dimension P of the case 2 and the dimension p of the magnetic core 1 in the same direction is larger than the change ΔP of the inner dimension of the case 2 in the direction. (Min (P−p)> ΔP). For example, when paying attention to the length direction, the magnetic core 1 and the case 2 have a minimum value of the difference between the length L of the case 2 and the length l of the magnetic core 1 in the length direction. It is designed to be larger than the change amount ΔL of the internal dimension of the case 2 in the direction.

The amount of change ΔP of the inner dimension of the case 2 is the maximum value of the dimension of the case 2 that contracts due to thermal contraction at the time of inductor manufacture (when the housing 4 is formed). The heat shrinkage during the manufacture of the inductor is, for example, from the curing temperature (85 degrees to 150 degrees) when thermosetting the thermosetting resin or the temperature (180 degrees to) when the thermoplastic resin is injection molded to room temperature. There is heat shrinkage when returning. If the minimum value of the inner dimension of the shrinking case 2 is P _MIN , ΔP = P−P _MIN is obtained.

The change amount ΔP is the product of the linear expansion coefficient α (% / ° C.) of the case 2, the inner dimension P of the case 2, and the temperature change amount ΔT (° C.) (ΔP = αPΔT). The temperature change amount ΔT is the maximum value of the temperature change amount in case 2 that rises when the inductor is manufactured. ΔT = T _MAX −T, where T is the temperature of Case 2 at the lowest temperature at which the inductor is operated (operating temperature of the inductor), and T _MAX is the maximum temperature of Case 2 that rises when the inductor is manufactured. The temperature T of the case 2 can be arbitrarily set according to the installation environment of the inductor. For example, when the operating temperature of the EV is -10 degrees to 40 degrees, T is -10 degrees.

From the above, the magnetic core 1 and the case 2 are designed so that min (P−p)> αPΔT holds in each direction. That is, the following formulas are established at arbitrary locations in the length direction, the width direction, and the height direction.
Magnetic flux direction: L-1> αLΔT
Width direction: W-w> αWΔT
Height direction: Hh> αHΔT
For example, when α = 0.01% / ° C., L = 100 mm, and ΔT = 100 ° C., l <99 mm.

  By designing the magnetic core 1 and the case 2 in this way, even when the case 2 is thermally contracted, the stress due to the thermal contraction of the case 2 is not directly applied to the magnetic core 1. can do.

Since the buffer material 5 is provided between the magnetic core 1 and the case 2, the total thickness Q in each direction is the difference between the inner dimension P of the case 2 and the dimension p of the magnetic core 1. (Q = P−p). The total thickness value Q is the total value of the thickness of the buffer material 5 provided on one side of the magnetic core 1 and the thickness of the buffer material 5 provided on the other side of the magnetic core 1. It is. For example, as shown in FIG. 2, the thickness of the buffer material 5 provided on the upper side of the magnetic core 1 is q ₁ , and the thickness of the buffer material 5 provided on the lower side of the magnetic core 1 is q ₂ . In this case, the total value Q of the thicknesses of the buffer materials 5 in the height direction is Q = q ₁ + q ₂ .

  As described above, according to the present embodiment, the casing 4 can improve the strength and heat dissipation of the inductor. In addition, the case 2 and the buffer material 5 can suppress the stress applied to the magnetic core 1 due to the hardening shrinkage of the housing 4. Furthermore, the buffer material 5 can suppress the stress applied to the magnetic core 1 due to the thermal contraction of the case 2. Therefore, it is possible to suppress a decrease in the L value of the inductor and an increase in core loss. Further, the reinforcing portion 6 can reinforce the strength of the inductor and improve the load resistance.

(Second Embodiment)
Next, an inductor according to a second embodiment will be described with reference to FIGS. FIG. 4 is an XY plane sectional view showing an example of the inductor according to the present embodiment. 5 is a cross-sectional view taken along the line AA in FIG. 4 (YZ plane cross-sectional view). As shown in FIGS. 4 and 5, the inductor according to the present embodiment further includes a bobbin 7.

  The bobbin 7 is a cylindrical member for winding the winding 3 around the surface, and is formed of an insulating material. The inductor may be formed by manufacturing the bobbin 7 wound with the winding 3 and the case 2 containing the magnetic core 1 and then inserting the case 2 into the hollow portion of the bobbin 7. Further, the case 2 and the bobbin 7 may be integrally formed.

(Third embodiment)
Next, an inductor according to a third embodiment will be described with reference to FIGS. FIG. 6 is an XY plane cross-sectional view showing an example of the inductor according to the present embodiment. FIG. 7 is a cross-sectional view (YZ plane cross-sectional view) taken along line AA in FIG. As shown in FIGS. 6 and 7, the inductor according to this embodiment further includes a conductor plate 8.

  The conductor plate 8 is provided so as to cover at least a part of the surface of the housing 4. By providing the conductor plate 8, the electromagnetic field in the direction in which the conductor plate 8 is provided can be shielded. When this inductor is used as an inductor for wireless power transmission, the conductor plate 8 is not provided on the surface of the housing 4 facing the power transmission direction, but is provided on the other surface. For example, when the power transmission direction is the upward direction in FIG. 7, the conductor plate 8 is preferably provided so as to cover the side surface and the bottom surface of the housing 4 as shown in FIG. 7.

(Fourth embodiment)
Next, an inductor according to a fourth embodiment will be described with reference to FIG. FIG. 8 is a YZ plane sectional view showing an example of the inductor according to the present embodiment. As shown in FIG. 8, the inductor according to this embodiment further includes a fiber layer 9.

  The fiber layer 9 is formed of a fiber reinforced plastic structure (FRP structure) including at least one type of fiber. The fiber layer 9 can be formed at any location in the housing 4 or on the housing 4. By forming the fiber layer 9, the strength and load resistance of the inductor can be improved. As shown in FIG. 8, when the fiber layer 9 forms the fiber layer 9 above the case 2, the load resistance in the height direction of the inductor is improved.

  The fiber layer 9 is formed by, for example, casting a first resin after arranging fibers at a predetermined position. Thereby, it forms in FRP and the housing | casing 4 which consist of 1st resin and a fiber.

  Moreover, after forming the housing | casing 4, the fiber layer 9 may be formed by arrange | positioning a fiber on the housing | casing 4 and casting 3rd resin different from 1st resin. As a result, an FRP made of the third resin and the fiber is formed on the housing 4.

  As the fibers forming the fiber layer 9, for example, glass fibers, resin fibers, carbon fibers, and conductor wires such as aluminum and copper are used. Further, as the third resin, a thermosetting resin such as an epoxy resin, a thermoplastic resin such as polypropylene, an ABS resin, or polyethylene, and glass can be used.

(Fifth embodiment)
Next, an inductor according to a fifth embodiment will be described with reference to FIGS. The inductor according to this embodiment includes a fiber layer 9. 9 and 10 are schematic views showing an example of the fiber layer 9 according to the present embodiment. As shown in FIGS. 9 and 10, the fiber layer 9 according to this embodiment includes conductive fibers 91 and insulating fibers 92.

  The conductive fibers 91 are arranged so that adjacent fibers do not contact each other. The conductive fiber 91 is, for example, a conductor wire such as carbon fiber, aluminum, or copper. By forming the fiber layer 9 using the conductive fibers 91, the strength of the fiber layer 9 can be improved. Also, as shown in FIG. 9, when the conductive fibers 91 are arranged in a predetermined direction, the conductive fibers 91 act like a polarizing plate, and a specific polarization incident on the inductor is reflected. Thereby, the leakage electromagnetic field intensity | strength of a harmonic can be reduced.

  The insulating fiber 92 is, for example, glass fiber or resin fiber. When the conductive fibers 91 are in contact with each other and a loop is formed by the conductive fibers 91, an eddy current flows through the loop, the loss of the inductor increases, the loop current shields the magnetic flux, and the electrical characteristics deteriorate. To do. Therefore, the insulating fibers 92 are arranged so that the adjacent conductive fibers 91 do not contact each other. Thereby, deterioration of the electrical characteristics of the inductor can be suppressed.

  The fiber layer 9 according to the present embodiment is formed of, for example, a woven fabric using the conductive fibers 91 as warp yarns and the insulating fibers 92 as weft yarns, and a resin. Further, the fiber layer 9 may include a plurality of layers of conductive fibers 91 arranged in a predetermined direction. Thereby, the leakage electromagnetic field intensity of the harmonic can be further reduced.

  FIG. 10 shows a fiber layer 9 having two layers of conductive fibers 91 arranged in a predetermined direction. Each layer of the conductive fiber 91 is laminated so that the arrangement direction is orthogonal. In addition, the conductive fibers 91 of each layer are insulated by insulating fibers 92 so that adjacent fibers do not contact each other. When the fiber layer 9 has such a laminated structure, an insulating layer (not shown) is preferably provided between the layers of the conductive fibers 91 in order to insulate the layers of the conductive fibers 91. The insulator layer can be formed of the insulating fiber 92, the first resin, the third resin, and the like.

(Sixth embodiment)
Next, an inductor according to a sixth embodiment will be described with reference to FIGS. 11 and 12 are YZ plane sectional views showing an example of the inductor according to this embodiment. As shown in FIGS. 11 and 12, the inductor according to the present embodiment further includes a protective layer 10.

  The protective layer 10 includes at least one of sand and gravel, and is provided in or on the housing 4. By providing the protective layer 10, the strength and wear resistance of the inductor can be improved.

  The protective layer 10 is formed by, for example, casting a first resin after placing sand or gravel at a predetermined position. Thereby, as shown in FIG. 11, the protective layer 10 is formed in the housing 4. Moreover, after forming the housing | casing 4, the protective layer 10 may be formed by arrange | positioning sand and gravel on the housing | casing 4, and casting 4th resin different from 1st resin. Thereby, the protective layer 10 is formed on the housing 4.

  Furthermore, the protective layer 10 may be formed by casting the first resin, the third resin, the fourth resin, and the like after placing sand, gravel, and fibers at predetermined positions. . Thereby, as shown in FIG. 12, the fiber layer 9 and the protective layer 10 can be integrally formed.

(Seventh embodiment)
Next, an inductor according to a seventh embodiment will be described with reference to FIG. FIG. 13 is a YZ plane sectional view showing an example of the inductor according to the present embodiment. As shown in FIG. 13, the inductor according to this embodiment further includes an uneven pattern 11.

  The uneven pattern 11 is provided so as to cover at least a part of the surface of the housing 4. By providing the concavo-convex pattern 11, the slip resistance of the inductor surface can be improved. The inductor of FIG. 13 includes the uneven pattern 11 only on the surface of the housing 4, but the uneven pattern 11 may be provided on the surface of the conductor plate 8. Further, when the fiber layer 9, the protective layer 10, or the like is formed on the housing 4, an uneven pattern may be formed on the surface of the fiber layer 9 or the protective layer 10.

(Eighth embodiment)
Next, an inductor according to an eighth embodiment will be described with reference to FIG. FIG. 14 is a YZ plane sectional view showing an example of the inductor according to the present embodiment. As shown in FIG. 14, the inductor according to the present embodiment further includes a paint part 12.

  The coating unit 12 is provided so as to cover at least a part of the surface of the housing 4. The coating unit 12 may be formed by painting the surface of the housing 4 or may be formed by sticking a painted sheet or the like to the surface of the housing 4.

  By providing the coating part 12, it is possible to improve the slip resistance of the surface of the inductor, and to improve the weather resistance and water resistance of the inductor. The inductor of FIG. 14 includes the painted portion 12 only on the surface of the housing 4, but the painted portion 12 may be provided on the surface of the conductor plate 8. Further, when the fiber layer 9, the protective layer 10, or the like is formed on the housing 4, the coating portion 12 may be provided on the surface of the fiber layer 9 or the protective layer 10.

(Ninth embodiment)
Next, an inductor according to a ninth embodiment will be described with reference to FIG. FIG. 15 is a YZ plane sectional view showing an example of the inductor according to the present embodiment. As shown in FIG. 15, the inductor according to this embodiment further includes a cover 13.

  The cover 13 is provided so as to cover at least a part of the surface of the housing 4 facing the power transmission direction of the inductor. By providing the cover 13, the strength and weather resistance of the inductor can be improved. The cover 13 is formed of an arbitrary insulating material having high strength, weather resistance, heat resistance, water resistance, wear resistance, and the like according to the purpose. The cover 13 may be the fiber layer 9 and the protective layer 10 formed on the housing 4, and may have the uneven pattern 12 and the coating portion 13 on the surface.

(10th Embodiment)
Next, an inductor according to a tenth embodiment will be described with reference to FIGS. 16 and 17 are YZ plane cross-sectional views illustrating an example of the inductor according to the present embodiment. As shown in FIGS. 16 and 17, the inductor according to the present embodiment includes a semiconductive portion 14.

  The semiconductive portion 14 is formed of a paint or sheet made of the above semiconductive material. The semiconductive portion 14 is provided on at least one of at least part of the inner surface of the case 2 and part of the surface of the housing 4.

  The inductor shown in FIG. 16 includes the semiconductive portion 14 between the entire inner surface of the case 2, that is, between the case 2 and the magnetic core 1. With such a configuration, the concentration of the electric field can be alleviated, so that partial discharge between the magnetic core 1 and the winding 3 can be suppressed.

  The inductor shown in FIG. 17 includes a semiconductive portion 14 between part of the surface of the housing 4, that is, between the housing 4 and the conductor plate 8. With such a configuration, the concentration of the electric field can be relaxed, so that partial discharge between the conductor plate 8 and the winding 3 can be suppressed.

  In addition, when providing the semiconductive part 14 in the inner surface of the case 2, you may provide the buffer material 5 and the semiconductive part 14, respectively, and you may form the buffer material 5 with a semiconductive material. In this case, the buffer material 5 serves as the semiconductive portion 14.

(Eleventh embodiment)
Next, an inductor according to an eleventh embodiment will be described with reference to FIGS. The inductor according to the present embodiment includes a magnetic core 1 formed by arranging a plurality of magnetic pieces 15 in a planar shape and coupling them together. Each magnetic piece 15 has a generally flat plate shape, and the magnetic core 1 has a large plate shape as a whole. FIG. 18 is an XY plane sectional view showing an example of the magnetic core 1 according to the present embodiment. FIG. 19 is a YZ plane sectional view showing an example of the magnetic core 1 according to the present embodiment.

  Each magnetic piece 15 is made of ferrite, a dust core, an electromagnetic steel plate, or the like. The reason why the magnetic core 1 is formed from the plurality of magnetic pieces 15 is as follows.

  When an inductor is used for wireless power transmission, the size of the inductor is determined according to the transmitted power and distance. For example, when power is transmitted to a position about 10 cm away, a large inductor having a side of several tens of cm is used. When the magnetic core 1 is formed of ferrite, a dust core, or the like, it is difficult to manufacture a large core due to the molding process and firing process. Therefore, as in this embodiment, a plurality of small magnetic pieces 15 are combined and used as a large inductor and a core.

  The plurality of magnetic body pieces 15 forming the magnetic body core 1 are coupled via a fluid material filled with a magnetic body material. As the magnetic material to be filled, for example, a powdery or granular material can be used. Moreover, as a fluid material, for example, an adhesive composed of a resin material such as an epoxy resin or silicon can be used. In FIG. 15, each magnetic piece 15 is bonded by an adhesive 16 filled with ferrite powder as magnetic powder.

  Adhesion between the magnetic body pieces 15 is performed, for example, by applying an adhesive 16 to the side surfaces of the magnetic body pieces 15 and pressing the magnetic body pieces 15 against each other for a predetermined time or more. Thereby, the magnetic core 1 which suppresses generation | occurrence | production of the area | region with a low relative magnetic permeability by the clearance gap of air etc. between the magnetic body pieces 15 can be formed. Therefore, local concentration of magnetic flux in the magnetic core 1 is suppressed, and core loss can be reduced.

  In the present embodiment, the magnetic pieces 15 may be bonded to each other using a fluid material such as a resin-based material that has no or weak adhesive force and is filled with a magnetic powder. Moreover, the structure which couple | bonds each magnetic body piece 15 using the material which consists only of ferrite powder is also possible. In this case, in order to maintain the coupling between the magnetic body pieces 15, as shown in FIG. 19, each magnetic body piece 15 is bonded to the both surfaces or one side of the magnetic body core 1 with an adhesive. May be fixed.

  As the sheet 17, a polyimide film, a silicon-based sheet, an acrylic-based sheet, or the like can be used. Further, as the sheet 17, a glass cloth may be used instead of the above-described sheet. The adhesive that bonds the sheet 17 may be, for example, a resin material such as unsaturated polyester.

(Twelfth embodiment)
Next, a wireless power transmission device according to the twelfth embodiment will be described with reference to FIGS. The wireless power transmission device according to the present embodiment includes the inductor according to each of the embodiments described above. The wireless power transmission device here includes a power receiving device and a power transmission device for wireless power transmission. Hereinafter, the power receiving device and the power transmitting device will be described separately.

  FIG. 20 is a block diagram illustrating a schematic configuration of the power receiving device 100 according to the present embodiment. As shown in FIG. 20, the power receiving apparatus 100 includes an inductor unit 101, a rectifier 102, a DC / DC converter 103, and a storage battery 104.

  The inductor unit 101 includes one or more inductors according to the above-described embodiments. In the power receiving device 100, the inductor receives power by resonating with the inductor on the power transmission side. The received power is input to the rectifier 102. The inductor unit 101 may include a capacitor that forms a resonance circuit or a circuit for improving the power factor together with the inductor.

  The rectifier 102 rectifies the AC power input from the inductor unit 101 into DC power. The rectifier 102 is configured by a bridge circuit using a diode, for example. The power rectified by the rectifier 102 is input to the DC / DC converter 103.

  The DC / DC converter 103 adjusts the voltage so that an appropriate voltage is applied to the storage battery 104. The voltage adjusted by the DC / DC converter 103 is input to the storage battery 104. Note that the power receiving apparatus 100 may be configured without the DC / DC converter 103.

  The storage battery 104 stores the electric power input from the DC / DC converter 103 or the rectifier 102. An arbitrary storage battery such as a lead storage battery or a lithium ion battery can be used as the storage battery 104. Note that the power receiving device 100 may be configured without the storage battery 104.

  FIG. 21 is a block diagram illustrating a schematic configuration of the power transmission device 110 according to the present embodiment. The power transmission device 110 includes an inductor unit 101 and an AC power source 105 as shown in FIG.

  The AC power source 105 inputs AC power to the inductor unit 101. For example, the AC power supply 105 receives power from a commercial power supply, rectifies the input power, converts it into AC power using an inverter circuit, and inputs the AC power to the inductor unit 101. Further, the AC power source 105 can be configured to include a circuit for adjusting the voltages of commercial power, DC power, and AC power, and a power factor correction circuit called a PFC circuit.

  The inductor of the inductor unit 101 generates an AC magnetic field by the electric power input from the AC power source 105 and transmits the AC magnetic field to the inductor on the power receiving side.

  Since the power receiving apparatus 100 and the power transmitting apparatus 110 described above transmit power through the inductors according to the above-described embodiments, the increase in inductor loss due to the manufacturing method is small. Therefore, the power receiving device 100 and the power transmitting device 110 can transmit power with high transmission efficiency.

  Note that the present invention is not limited to the above-described embodiments as they are, and can be embodied by modifying the components without departing from the scope of the invention in the implementation stage. Moreover, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the above embodiments. Further, for example, a configuration in which some components are deleted from all the components shown in each embodiment is also conceivable. Furthermore, you may combine suitably the component described in different embodiment.

1: Core, 2: Case, 3: Winding, 4: Resin, 5: Buffer material, 6: Reinforcing part, 7: Bobbin, 8: Conductor plate, 9: Fiber layer, 10: Protective layer, 11: Concavity and convexity pattern , 12: Painted part, 13: Cover, 14: Semiconductive part, 15: Magnetic piece, 16: Adhesive, 17: Sheet, 41: Space, 91: Conductive fiber, 92: Insulating fiber, 100: Power reception Device: 101: 101: inductor unit, 102: rectifier, 103: DC / DC converter, 104: storage battery, 105: AC power supply, 110: power transmission device

Claims (20)

A plurality of magnetic cores;
One or more cases for accommodating the magnetic core inside,
A winding wound around the case; a housing formed of a first resin so as to cover the case and the winding;
A reinforcing portion formed at least in part between the magnetic cores;
With
An inductor in which a difference between an inner dimension of the case and a dimension of the magnetic core in the same direction is larger than a change amount of the dimension of the case in the direction when the casing is formed. The inductor according to claim 1, wherein the reinforcing portion is formed by at least one of the case and a side surface of the case. The inductor according to claim 1, further comprising a fiber layer formed on or in the casing. The inductor according to claim 3, wherein the fiber layer is formed of a fiber reinforced plastic including at least one fiber. The inductor according to claim 3 or 4, wherein the fiber layer includes an insulating fiber and a conductive fiber. The inductor according to any one of claims 1 to 5, further comprising a protective layer formed on or in the casing and including at least one of sand and gravel. The amount of change in the size of the case is a product of the linear expansion coefficient of the case, the size of the case at an operating temperature, and the amount of change in the temperature of the case when the housing is formed. The inductor according to claim 6. The plurality of magnetic cores according to any one of claims 1 to 7, wherein the total cross-sectional area in the length direction of the vicinity of the winding is larger than the total cross-sectional area in the length direction of the other part. The inductor according to the item. The inductor according to any one of claims 1 to 8, wherein the case is formed of the first resin. The inductor according to any one of claims 1 to 9, further comprising a buffer material that fixes the magnetic core at least at a part between the case and the magnetic core. The inductor according to claim 10, wherein the buffer material is formed of a material having a lower elastic modulus than the first resin. The inductor according to claim 1, further comprising a bobbin around which the winding is wound. The inductor according to any one of claims 1 to 12, further comprising a conductor plate that covers at least a part of a surface of the housing. The inductor according to any one of claims 1 to 13, further comprising a concavo-convex pattern formed on at least a part of a surface of the casing. The inductor according to any one of claims 1 to 14, further comprising a coating portion formed on at least a part of a surface of the casing. The inductor according to any one of claims 1 to 15, further comprising an insulating cover that covers at least a part of a surface of the housing. The inductor according to any one of claims 1 to 16, further comprising a semiconductive portion made of a material having a higher conductivity than the first resin on at least a part of an inner surface of the case. 18. The semiconductor device according to claim 1, further comprising a semiconductive portion made of a material having a higher conductivity than the first resin, between the housing and a conductor plate covering at least a part of the surface of the housing. 2. The inductor according to item 1. The inductor according to any one of claims 1 to 18, wherein the magnetic core includes a plurality of magnetic pieces arranged in a plane and coupled to each other by a material including a magnetic material. A wireless power transmission device comprising the inductor according to any one of claims 1 to 19.

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