Magnetic cores, electronic components, and power supplies

Abstract

To provide a magnetic core that suppresses noise generated during operation, an electronic component using the magnetic core, and a power supply device using the electronic component. [Solution] The magnetic core 1 has a base portion 30 extending in the first axis direction, a pair of outer legs 10, 10 protruding from the base portion 30 along a second axis perpendicular to the first axis, and a middle leg portion 20 positioned between the pair of outer legs 10, 10 and protruding along the second axis. The relationship between the thickness value Li (mm) of the base portion 30 in the second axis direction and the height value Lf (mm) of the shorter of the pair of outer legs 10, 10 in the second axis direction satisfies the relationship Li / Lf ≥ 0.8.

Description

[Technical Field]

[0001] This invention relates to a magnetic core, an electronic component, and a power supply device. [Background technology]

[0002] Magnetic cores have often been designed with a shape that ensures a uniform magnetic flux density distribution within the material. However, in such shapes, exciting the magnetic core can sometimes produce a humming sound.

[0003] Patent Document 1 attempts to suppress noise by bonding together electromagnetic steel sheets with different magnetostrictive changes over time. Patent Document 2 attempts to suppress noise by using a non-magnetic reinforcing member separate from the magnetic core. Patent Document 3 attempts to suppress noise by detecting the frequency of noise generated by the operation of the device and adjusting it to a carrier frequency where no noise is generated.

[0004] However, these conventional methods required complex configurations. Therefore, there is a need for a simpler method to suppress noise during device operation. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2019-102692 [Patent Document 2] Japanese Patent Publication No. 2018-195786 [Patent Document 3] Japanese Patent Publication No. 2018-186663 [Overview of the project] [Problems that the invention aims to solve]

[0006] This invention has been made in view of the above circumstances, and its purpose is to provide a magnetic core or the like that suppresses noise generated during operation. [Means for solving the problem]

[0007] To achieve the above objective, the magnetic core according to the present invention, in the first aspect, A magnetic core having a base portion extending in a first axial direction, a pair of outer legs projecting from the base portion in a second axial direction perpendicular to the first axial direction, and a middle leg portion positioned between the pair of outer legs and projecting from the base portion in the second axial direction, The relationship between the thickness value Li (mm) of the base portion in the second axial direction and the height value Lf (mm) of the lower of the pair of outer legs in the second axial direction satisfies the relationship Li / Lf ≥ 0.8.

[0008] Furthermore, in order to achieve the above objective, the magnetic core according to the present invention, from a second perspective, A magnetic core having a base portion extending in a first axial direction, a pair of outer legs projecting from the base portion in a second axial direction perpendicular to the first axial direction, and a middle leg portion positioned between the pair of outer legs and projecting from the base portion in the second axial direction, The value of the thickness of the base portion in the second axial direction is Li (mm), the value of the height in the second axial direction of the lower of the pair of outer legs is Lf (mm), and the value of the density of the magnetic core is Ds (g / cm³). 3 ), with respect to the value La (mm) of the width of the base portion in the first axial direction, X = 1000 × Ds × Li / (La + 2 × Lf) 2 The formula represented by is characterized in that the value of X is 7.9 or greater.

[0009] According to our research, we have found that in an E-shaped magnetic core, if the sizes of each part of the magnetic core itself are in a predetermined relationship, it is possible to suppress the noise generated during operation. In other words, in a magnetic core that satisfies the relationship Li / Lf≧0.8, it is possible to sufficiently reduce the generated noise.

[0010] According to the inventors' research, they found that in an E-shaped magnetic core, when the size of each part of the magnetic core and the density of the magnetic core are in a predetermined relationship, the noise generated during operation can be suppressed. That is, X = 1000 × Ds × Li / (La + 2 × Lf) 2 In the formula represented by [formula], when the value of X is 7.9 or higher, the magnetic core is able to sufficiently reduce the sound generated.

[0011] Therefore, with such a magnetic core, a complex configuration is not required. By simply designing the size of each part and the density of the magnetic core to conform to these relationships, noise can be suppressed to a degree that complies with environmental standards, thus easily achieving reduced manufacturing costs and miniaturization of the device.

[0012] The electronic component according to the present invention comprises a magnetic core and a coil wound around the magnetic core. Such an electronic component with a magnetic core can significantly reduce the noise generated. Such an electronic component can be suitably used in power supply devices and the like, as a transformer.

[0013] Preferably, the magnetic core has a separate core that abuts against the outer legs of the magnetic core. With this configuration, the electronic component forms a closed magnetic circuit, reducing magnetic loss.

[0014] The power supply device according to the present invention comprises the electronic component and a switching circuit electrically connected to the electronic component. The power supply device having the electronic component can effectively prevent noise caused by magnetostriction of the core or attraction between cores. [Brief explanation of the drawing]

[0015] [Figure 1A] FIG. 1A is a plan view, viewed from one direction, schematically showing the configuration of a magnetic core according to an embodiment of the present invention. [Figure 1B] FIG. 1B is a plan view of the magnetic core shown in FIG. 1A, viewed from another direction. [Figure 1C] FIG. 1C is a plan view of the magnetic core shown in FIG. 1A, viewed from still another direction. [Figure 2] FIG. 2 is a front view showing the configuration of a part of an electronic component according to an embodiment of the present invention. [Figure 3] FIG. 3 is a schematic perspective view showing the configuration of an electronic component according to an embodiment of the present invention. MODE FOR CARRYING OUT THE INVENTION

[0016] Hereinafter, the present invention will be described based on embodiments shown in the drawings.

[0017] As shown in FIG. 1A, a magnetic core 1 according to one embodiment is a so-called E-shaped core. The magnetic core 1 includes a base portion 30 extending along the X-axis, a pair of outer leg portions 10, 10 protruding from the base portion 30 along the Z-axis, and a middle leg portion 20 disposed between the pair of outer leg portions 10, 10 and protruding along the Z-axis. In the drawings, the X-axis, Y-axis, and Z-axis are substantially perpendicular to each other. In the present embodiment, the X-axis corresponds to a first axis, and the Z-axis corresponds to a second axis. In the present specification, in the magnetic core 1, a direction close to the center line C in the X-axis direction may be referred to as the inner side, and a direction far from the center of the magnetic core 1 in the X-axis direction may be referred to as the outer side.

[0018] As shown in FIG. 1A, in the present embodiment, the magnetic core 1 has a width of length La in the X-axis direction, a height of length Lb in the Z-axis direction, and a depth of length Lc in the Y-axis direction (FIG. 1B), and has a symmetrical shape with the center line C in the X-axis direction as an axis of symmetry. The overall size of the magnetic core 1 is not particularly limited; for example, La is 30 to 110 mm, Lb is 8 to 50 mm, and Lc is 5 to 30 mm.

[0019] The magnetic core 1 is formed from a magnetic material. Examples of magnetic materials include magnetic materials with relatively high magnetic permeability, such as Mn-based ferrite, Ni-based ferrite, or metallic magnetic materials. The magnetic core 1 is formed by molding and sintering powders of these magnetic materials. The magnetic core 1 may also be formed by mixing the magnetic material with a resin or the like.

[0020] As shown in Figure 1A, the pair of outer legs 10, 10 each have a substantially rectangular parallelepiped shape. The outer leg 10 has an outer leg end face 11 that protrudes along the Z axis, with the base first surface 31 as its base end. The outer leg end face 11 constitutes the side surface of the outer leg 10 perpendicular to the Z axis. The outer leg 10 has a height of Lf (mm) in the Z axis direction. Lf represents the distance along the Z axis from the base first surface 31 to the outer leg end face 11.

[0021] As shown in Figure 1A, the outer leg portion 10 has an outer leg outer surface 12 and an outer leg inner surface 13. The outer leg outer surface 12 constitutes the outer side surface that is farther from the middle leg portion 20 along the X-axis, and the outer leg inner surface 13 constitutes the inner side surface that is closer to the middle leg portion 20 along the X-axis. The outer leg outer surface 12 and the outer leg inner surface 13 are each perpendicular to the Z-axis of the outer leg portion 10. The outer leg portion 10 has a width Lh (mm) in the X-axis direction. Lh represents the distance along the X-axis from the outer leg outer surface 12 to the outer leg inner surface 13.

[0022] The outer legs 10, 10 are each positioned at a distance of Le (mm) in the X-axis direction. Le represents the distance along the X-axis between the inner surface 13 of one outer leg 10 and the inner surface 13 of the other outer leg 10.

[0023] As shown in Figure 1C, the outer leg portion 10 has an outer leg first front surface 14a and an outer leg second front surface 14b. The outer leg first front surface 14a constitutes one of the sides of the outer leg portion 10 perpendicular to the Y-axis. The outer leg second front surface 14b is opposite the outer leg first front surface 14a along the Y-axis and constitutes the other side of the sides of the outer leg portion 10 perpendicular to the Y-axis.

[0024] As shown in Figure 1A, the middle leg portion 20 has a roughly rectangular parallelepiped shape. The middle leg portion 20 has a middle leg end face 21 that protrudes along the Z axis, with the base first surface 31 as its base end. The middle leg end face 21 forms a side surface perpendicular to the Z axis. In the middle leg portion 20, the distance along the Z axis from the base first surface 31 to the middle leg end face 21 is the same as the height Lf of the outer leg portion 10.

[0025] As shown in Figure 1A, the mid-leg portion 20 has a pair of mid-leg sides 22, 22. The mid-leg sides 22 constitute the sides of the mid-leg portion 20 perpendicular to the X-axis. The mid-leg portion 20 has a width Ld (mm) in the X-axis direction. Ld represents the distance between the mid-leg sides 22, 22 along the X-axis.

[0026] As shown in Figure 1C, the middle leg portion 20 has a first front surface 24a and a second front surface 24b. The first front surface 24a constitutes one of the sides of the middle leg portion 20 that are perpendicular to the Y-axis. The first front surface 24b is opposite the first front surface 24a of the inner leg along the Y-axis and constitutes the other side of the sides of the middle leg portion 20 that are perpendicular to the Y-axis.

[0027] As shown in Figure 1A, the base portion 30 has a substantially rectangular parallelepiped shape. The base portion 30 has a first base surface 31 which forms a side surface perpendicular to the Z axis, and a second base surface 33 which forms a side surface opposite to the first base surface 31. The base portion 30 has a thickness of Li (mm) in the Z axis direction. Li represents the distance along the Z axis from the first base surface 31 to the second base surface 33.

[0028] As shown in Figure 1A, the first base surface 31 is the base end of a pair of outer legs 10, 10 and a middle leg 20. The outer side of the first base surface 31 in the X-axis direction is connected to the inner surface 13 of the outer leg. The inner side of the first base surface 31 in the X-axis direction is connected to the side surface 22 of the middle leg.

[0029] As shown in Figure 1A, the base portion 30 has a pair of base outer surfaces 32, 32. The base outer surfaces 32 constitute the side surface of the base portion 30 perpendicular to the X-axis. The base outer surfaces 32 are arranged in the same plane as the outer leg outer surfaces 12 and are connected to the outer leg outer surfaces 12. The base portion 30 has a width of La (mm) in the X-axis direction. La represents the distance along the X-axis between the base outer surfaces 32, 32. In this embodiment, the distance along the X-axis between the outer leg outer surface 12 of one outer leg portion 10 and the outer leg outer surface 12 of the other outer leg portion 10 coincides with La.

[0030] As shown in Figure 1C, the base portion 30 has a first base front 34a and a second base front 34b. The first base front 34a constitutes one of the sides of the base portion 30 that are perpendicular to the Y-axis. The first base front 34a is arranged in the same plane as the first outer leg fronts 14a, 14a and the first middle leg front 24a, and is connected to the first outer leg fronts 14a, 14a and the first middle leg front 24a.

[0031] As shown in Figure 1C, the second base front 34b faces the first base front 34a along the Y-axis and constitutes the other side of the base portion 30 that is perpendicular to the Y-axis. The second base front 34b is arranged in the same plane as the second outer leg fronts 14b, 14b and the second middle leg front 24b, and is connected to the second outer leg fronts 14b, 14b and the second middle leg front 24b.

[0032] As shown in Figure 1A, in this embodiment, the magnetic core 1 has a height of Lb (mm) in the Z-axis direction. Lb represents the distance along the Z-axis from the second base surface 32 to the outer leg end surface 11, and in this embodiment, it is equal to the sum of Li and Lf.

[0033] As shown in Figure 1B, in this embodiment, the base portion 30 has a depth of Lc (mm) in the Y-axis direction. Lc represents the distance along the Y-axis from the first front surface 34a of the base to the second front surface 34b of the base. The depth of the outer leg portion 10 and the middle leg portion 20 in the Y-axis direction coincides with Lc.

[0034] In this embodiment, regardless of the overall size of the magnetic core 1, the relationship between the thickness value Li (mm) of the base portion 30 in the Z-axis direction shown in Figure 1A and the height value Lf (mm) of the shorter of the pair of outer legs 10, 10 in the Z-axis direction satisfies the relationship Li / Lf ≥ 0.8. In this embodiment, both outer legs have a symmetrical shape across the X-axis and both have the same height value Lf.

[0035] In this embodiment, regardless of the overall size of the magnetic core 1, the Z-axis thickness value Li (mm) of the base portion 30 shown in Figure 1A, the Z-axis height value Lf (mm) of the shorter of the pair of outer legs 10, 10, and the density value Ds (g / cm³) of the magnetic core 1 are as follows: 3 Regarding the width value La (mm) of the base portion 30 in the X-axis direction, X = 1000 × Ds × Li / (La + 2 × Lf) 2 In the formula represented by , the value of X is 7.9 or greater.

[0036] In the magnetic core 1 of this embodiment, the base portion 30, the outer legs 10, 10 and the middle leg portion 20 are each rectangular parallelepipeds and have the same depth, forming a standard E-shaped core, but it is not limited to this. For example, the magnetic core may be a PQ core in which the middle leg portion 20 is cylindrical and the inner surface 13 of the outer leg portion 10 is formed as a curved surface to conform to the shape of the side surface of the middle leg portion 20. In a PQ core, for example, when winding a coil around the middle leg portion, even thick wires or flat wires can be easily wound around it to form a coil with good adhesion. Alternatively, the magnetic core may be an EPC core in which the depth of the middle leg portion 20 is shorter than the depth of the outer legs 10, 10, and it is thinner in the Y-axis direction.

[0037] As shown in Figure 1A, in this embodiment, the heights Lf of each outer leg portion 10, 10 and the middle leg portion 20 are the same, and the outer leg end face 11 of one outer leg portion 10, the outer leg end face 11 of the other outer leg portion 10, and the middle leg end face 21 of the middle leg portion 20 are arranged on the same plane, but are not limited to this. For example, the middle leg portion 20 may be shorter than the outer leg portions 10, 10, and the middle leg end face 21 may be positioned closer to the base first surface 31 along the Z axis than the outer leg end face 11.

[0038] Furthermore, in this embodiment, the outer legs 10, 10 have a symmetrical shape in the X-axis direction, but they may be asymmetrical. For example, one outer leg 10 may be longer than the other outer leg 10, and the outer leg end face 11 of one outer leg 10 may be positioned closer to the base first surface 31 along the Z-axis than the outer leg end face 11 of the other outer leg 10.

[0039] In this embodiment, in the E-shaped magnetic core 1, the relationship between the thickness value Li of the base portion 30 and the height Lf of the outer leg portion 10 is Li / Lf ≥ 0.8. Also, X = 1000 × Ds × Li / (La + 2 × Lf) 2 In the formula represented by , the value of X is 7.9 or greater.

[0040] In this relationship, the magnetic core 1 can sufficiently reduce the noise generated during operation, regardless of its overall size. Therefore, in the magnetic core 1 of this embodiment, noise can be suppressed simply by designing the sizes of the base portion 30 and the outer leg portion 10 to satisfy this relationship. Furthermore, the relationship between Li and Lf is preferably Li / Lf≧0.9, and more preferably Li / Lf≧1.0. It is also more preferable that the value of formula X is 8.8 or higher.

[0041] Therefore, with such a magnetic core, it is possible to suppress noise to a degree that complies with environmental standards simply by designing the size of each part and the density of the magnetic core to meet these relationships, without requiring a complex configuration. This makes it easy to reduce manufacturing costs and miniaturize the device.

[0042] As shown in Figure 2, an electronic component 100 according to one embodiment has a magnetic core 1 and a separate core 2 that is abutted against a pair of outer legs 10, 10 of the magnetic core 1. In this embodiment, the separate core 2 is made of the same material as the magnetic core 1 and is formed to have the same shape and size as the magnetic core 1.

[0043] As shown in Figure 3, a coil 110 is wound around the middle leg portion 20 of the magnetic core 1. For example, the coil 110 can be made by covering a core material made of a good conductor such as copper (Cu) with an insulating material such as imide-modified polyurethane, and further covering the outermost surface with a thin resin film such as polyester.

[0044] As shown in Figure 2, in this embodiment, the electronic component 100 has outer legs 10, 10 of the magnetic core 1 and a pair of outer legs of another core 2 abutted together. Also, the middle leg 20 of the magnetic core 1 and the middle leg of the other core 2 abutted together. A closed magnetic circuit is formed by one outer leg 10, base portion 30, middle leg 20 of the magnetic core 1 and the other core 2. Furthermore, a closed magnetic circuit is formed by the other outer leg 10 of the magnetic core 1, base portion 30, middle leg 20 and the other core 2.

[0045] For example, by passing an electric current through the coil 110 shown in Figure 3, a magnetic flux in the direction of D1 is generated in the region enclosed by one outer leg 10, base 30, middle leg 20 of the magnetic core 1 shown in Figure 2, and the other core 2. In addition, a magnetic flux in the direction of D2 is generated in the region enclosed by the other outer leg 10, base 30, middle leg 20 of the magnetic core 1, and the other core 2. In this embodiment, a closed magnetic path is formed, so magnetic losses can be reduced.

[0046] In this embodiment, the middle leg portion 20 of the magnetic core 1 is in contact with the middle leg portion of another core 2. However, the height of either middle leg portion may be shortened to form a gap of a predetermined width between the middle leg portion 20 of the magnetic core 1 and the middle leg portion of the other core 2.

[0047] In this embodiment, the separate core 2 is formed using the same material as the magnetic core 1 and has the same shape and size as the magnetic core 1. However, it may be made of a different material than the magnetic core 1, and its shape and size may differ from those of the magnetic core 1. For example, the separate core 2 may be an I-shaped core without outer and middle legs. Even in this case, a closed magnetic circuit can be formed.

[0048] As shown in Figure 3, in the electronic component 100 of this embodiment, the coil 110 is wound around the middle leg portion 20 of the magnetic core 1, but the coil 110 may also be wound around the outer leg portion 10 or the base portion 30. Also, in this embodiment, the electronic component 100 has one coil 110 wound around it, but multiple coils may be wound around the same portion. The electronic component 100 of this embodiment can be suitably used as an inductor, transformer, or reactor by being a coil device in which the coil 110 is wound around the magnetic core 1.

[0049] As the wire used to form the coil, for example, a core material made of a good conductor such as copper (Cu) can be covered with an insulating material such as imide-modified polyurethane, and the outermost surface can be covered with a thin resin film such as polyester.

[0050] Furthermore, the electronic component 100 may be an embodiment in which the coil is not wound around the magnetic core 1. For example, the electronic component 100 can be suitably used as an inductor, transformer, reactor, etc., by sandwiching a substrate or the like with an embedded coil between the magnetic core 1 and another core 2 as shown in Figure 2.

[0051] One power supply according to this embodiment has the electronic component 100 shown in Figure 3. It is known that in power supply devices, high-frequency pulses created by the ON / OFF switching of switching elements can cause magnetostriction of the core and attraction between cores. In a power supply device having the electronic component 100 according to this embodiment, the power supply device configured in this way can effectively prevent noise caused by magnetostriction of the core and attraction between cores. Note that the power supply device may use an electronic component having a magnetic core as shown in Figure 1A.

[0052] It should be noted that the present invention is not limited to the embodiments described above, and can be modified in various ways within the scope of the present invention. [Examples]

[0053] Values La to Li (in mm) of each part of the E-shaped magnetic core shown in Fig. 1A and the density Ds (g / cm 3 ) were changed to fabricate magnetic cores for working examples and comparative examples. Table 1 shows the values La to Li (in mm) of each part of the magnetic cores according to each working example and comparative example, and the density Ds (g / cm 3 ) of the magnetic cores.

[0054] The electronic component shown in Fig. 3 including the fabricated magnetic cores for working examples and comparative examples was mounted on a DCDC converter, and a noise emission measurement test was performed. The noise emission measurement test was conducted by placing the electronic component in a simple anechoic box. For measurement, the magnetic core and the microphone tip of a sound level meter were placed at positions separated by 30 mm, and the sound pressure level was measured. The sound pressure level was measured using a sound level meter (LA-5570) manufactured by Ono Sokki. The results of the noise emission measurement test are shown in Table 1. The data shows overall values (OA values) after A-weighting conversion. The A-weighting is a value to which frequency weighting is applied as a quantity representing the sound pressure level based on human auditory perception. The OA value is the sum of the respective frequency-analyzed sound pressure levels. Table 1 also shows the value of Li / Lf, and X=1000×Ds×Li / (La+2×Lf) 2 shows the value of mathematical expression X represented thereby.

[0055]

Table 1

[0056] When the value of Li / Lf was 0.8 or more, the maximum noise emission measurement data was 58 dB. When the value of Li / Lf was 0.9 or more, the maximum noise emission measurement data was 54 dB. When the value of Li / Lf was 1.0 or more, the maximum noise emission measurement data was 51 dB. When the value of X was 7.9 or more, the maximum noise emission measurement data was 59 dB. When the value of X was 8.8 or more, the maximum noise emission measurement data was 47 dB.

[0057] Magnetic cores with a Li / Lf value of 0.8 or higher, or magnetic cores with an X value of 7.9 or higher, were able to suppress noise levels to meet Japanese daytime environmental standards for areas used for commercial and industrial purposes in conjunction with a considerable number of residences. Furthermore, magnetic cores with a Li / Lf value of 0.8 or higher were able to suppress noise levels to meet Japanese daytime environmental standards for areas used exclusively for residential purposes and areas used primarily for residential purposes. With a Li / Lf value of 1.0 or higher, noise levels could be suppressed to a level close to Japanese daytime environmental standards for areas requiring particular quietness, such as areas where medical facilities, social welfare facilities, etc., are concentrated. Magnetic cores with an X value of 8.8 or higher were able to suppress noise levels to meet Japanese daytime environmental standards for areas requiring particular quietness, such as areas where medical facilities, social welfare facilities, etc., are concentrated. [Explanation of Symbols]

[0058] 1…Magnetic core 10...Outer leg 11...Outer leg end surface 12…Outer surface of outer leg 13…Inner surface of outer leg 14a...Outer leg, first front view 14b…Second front of outer leg 20...middle leg 21…Middle leg end surface 22…Middle leg side 24a…first front of middle leg 24b…second front of middle leg 30...Base section 31...Base, first side 32…Base exterior 33...Base, side 2 34a...Base 1st Front 34b...Base 2nd Front 2... Separate core 100... Electronic components 110... Coil

Claims

1. A magnetic core having a base portion extending in a first axial direction, a pair of outer legs projecting from the base portion in a second axial direction perpendicular to the first axial direction, and a middle leg portion positioned between the pair of outer legs and projecting from the base portion in the second axial direction, The relationship between the thickness value Li (mm) of the base portion in the second axial direction and the height value Lf (mm) of the lower of the pair of outer legs in the second axial direction satisfies the relationship Li / Lf ≥ 0.

8. A magnetic core characterized in that the relationship between the thickness value Li (mm) of the base portion in the second axial direction and the width value Lh (mm) of the pair of outer legs in the first axial direction satisfies the relationship Li / Lh ≥ 1.

3.

2. A magnetic core having a base portion extending in a first axial direction, a pair of outer legs projecting from the base portion in a second axial direction perpendicular to the first axial direction, and a middle leg portion positioned between the pair of outer legs and projecting from the base portion in the second axial direction, The value of the thickness of the base portion in the second axial direction, Li (mm), the value of the height in the second axial direction of the lower of the pair of outer legs, Lf (mm), and the value of the density of the magnetic core, Ds (g / cm³). 3 ), with respect to the value La (mm) of the width of the base portion in the first axial direction, X=1000×Ds×Li / (La+2×Lf) 2 In the formula represented by , the value of X is 7.9 or greater, A magnetic core characterized in that the relationship between the thickness value Li (mm) of the base portion in the second axial direction and the width value Lh (mm) of the pair of outer legs in the first axial direction satisfies the relationship Li / Lh ≥ 1.3.

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