JP2596830Y2 - Magnetic core - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic core made of ferrite or the like used for a transformer or an inductance element.

[0002]

2. Description of the Related Art Conventionally, a typical example of a magnetic core composed of a central leg, an outer leg, and a bottom connecting these legs is as follows.
A magnetic core called a pot core is known.
An ER core shown in FIG. 28, a PQ core shown in FIG. 29, an RM core shown in FIG. 30 as a shape in which a part of the outer leg and the bottom of the pot core is cut out to form an opening,
Various magnetic cores called an LP core shown in FIG. 31 and an EPC core shown in FIG. 32 are known.

FIG. 27 is a plan sectional view of a conventional ER core. In FIG. 27, an ER core 1 has a cylindrical central leg 2 and an outer leg 3 having an outer peripheral surface as a circumferential surface. And an inner wall surface 5 of the outer leg portion 3 is a circular arc surface concentric with the outer peripheral surface of the central leg portion 2. That is, the outer peripheral surface of the center leg 2 is a circumferential surface having a radius R ₁ , and the arc surface of the inner wall surface 5 is defined as a distance R ₂ between the center of the center leg 2 and the inner wall surface 5 as a radius of curvature. Is an arc surface. Further, on the longitudinal side surface of the ER core, there is a portion where the outer leg portion 3 is not provided,
This is the opening 6.

[0004]

However, when the inner wall surface 5 of the outer leg 3 is formed by an arc surface concentric with the center leg 2 as shown in FIG. 27, the following problem occurs. That is, the center leg 2 has a cylindrical shape, and the bobbin winding portion mounted on the center leg portion 2 has a circumferential surface, and the winding portion wound on the bobbin winding portion also has an annular shape. ,
Since the lead wire and the intermediate tap are pulled out from the openings 6 on both sides where the outer leg 3 is not provided, the winding portion wound around the bobbin does not become a perfect circle like the imaginary line J, but the imaginary line K. It tends to be an elliptical shape swelling to the side where the opening 6 exists as shown in FIG. For this reason, it becomes easy to come into contact with the winding portion at the edge a of the outer leg portion 3 or a part of the inner wall surface of the outer leg portion, and when the wound bobbin is forcibly incorporated into the ER core 1, the wire is damaged. And there was a danger of dielectric breakdown.

Further, in the ER core shown in FIG. 27, there is also a ER core in which a chamfer is provided only at an edge a in order to prevent chipping of the core. In some cases, which is insufficient to prevent the above-mentioned inconvenience.

[0006] In PQ cores, RM cores, LP cores, EPC cores and the like other than the ER core, all or a part of the inner wall surface of the outer leg part has a circumferential surface that forms all or a part of the central leg part. Since it is formed by concentric arc surfaces, similar inconveniences have occurred.

In view of the above, the present invention increases the distance between the inner wall surface of the outer leg and the central leg at the opening without substantially reducing the cross-sectional area of the outer leg and without increasing the external dimensions. It is an object of the present invention to provide a magnetic core which can be easily assembled without bringing the winding portion into contact with the edge of the outer leg portion or a part of the inner wall surface of the outer leg portion.

[0008]

In order to achieve the above object, a first magnetic core according to the present invention comprises a center leg, an outer leg, and a bottom connecting these legs. Having a structure with an opening where the outer leg is not provided,
Furthermore, it has a radius of curvature larger than the distance between the center of the central leg and the inner wall surface of the outer leg , and
In the center leg, the center moves away from the inner wall surface.
The inner surface of the outer leg portion is constituted by an arc surface positioned on a straight line extending in parallel with the longitudinal direction from the center or a surface similar to the arc surface.

The second magnetic core according to the present invention comprises a central leg, an outer leg, and a bottom connecting the two legs, and the outer leg of the central leg is provided on the outer leg. At least a part opposing is an arc surface, and has a structure having an opening where the outer leg is not provided,
Further, the center leg has a second radius of curvature larger than the distance between the center of the first radius of curvature with respect to the arc surface and the inner wall surface of the outer leg, and the second radius of curvature is larger than the distance between the second radius of curvature.
The first half of curvature in a direction in which the heart moves away from the inner wall surface;
The inner surface of the outer leg portion is constituted by an arc surface or a surface approximating the arc surface which is located on a straight line extending in parallel with the longitudinal direction from the center of the diameter.

[0010]

In the magnetic core of the present invention, the inner wall surface of the outer leg is formed with a radius of curvature larger than or similar to the conventional one, so that the outer dimensions are not increased and the cross-sectional area of the outer leg is increased. The distance between the edges of the inner wall surfaces of the outer legs facing each other or the distance between the edge and the center leg can be increased without substantially reducing the distance. As a result, even when the winding portion is swelled in an elliptical shape by a lead wire or the like, the mounting of the winding portion becomes easy, and the risk of damaging the wire can be eliminated, and the problem of insulation breakdown can be solved. In addition, since the outer dimensions and the shape and dimensions of the central leg can be made the same, and the shape and dimensions of the bobbin used can be made the same, it can be used as it is by replacing the conventional magnetic core with the inner wall of the outer leg. By providing an increased gap between the end edge and the winding portion on the opening side side compared with the conventional magnetic core, the heat radiation from the heat generated by the magnetic core or the winding is improved.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a magnetic core according to the present invention will be described below with reference to the drawings.

FIGS. 1 to 3 show a first embodiment of the present invention, in which the present invention is applied to an ER core. In these figures, the ER core 11 is composed of a cylindrical central leg portion 12 having an outer peripheral surface as a circumferential surface, an outer leg portion 13 and a rectangular bottom portion 14 connecting these, and a magnetic material such as ferrite. Are formed integrally. Here, the outer peripheral surface of the central leg portion 12 is a circumferential surface having a radius R ₁ , and a radius of curvature larger than a distance R ₂ between the center of the central leg portion 12 and the inner wall surface 15 of the outer leg portion 13. inner wall surface by an arc surface of the R ₃ 15
Is composed. Center f ₃ of the radius of curvature R ₃ is the center f ₃ of the center of the central leg 12 in the longitudinal side surfaces having through openings 16 are positioned on a straight line parallel (the radius of curvature R ₃ is
From the center of the central leg 12 in a direction away from the inner wall surface 15
Are located on a straight line extending parallel to the longitudinal direction.
You. ). Incidentally, illustrating the arcuate surface of the conventional case having an outer peripheral surface concentric with the radius of curvature R ₂ of the center leg 12 to the reference virtual line L. Further, although not shown, the center f ₃ of the radius of curvature R ₃ of the right inner wall surface 15 in FIG. 1 is in the symmetrical positions with respect to the central leg center.

In the first embodiment, the edge a of the inner wall surface 15 is retracted by the distance Δb as compared with the conventional virtual line L, and the distance between the edges of the opposing inner wall surface 15 (opening The opening size (b) of the sixteen (16) holes is increased as compared with the prior art.
For this reason, as described with reference to FIG. 27, there is no danger that the inner wall surface edge a and the winding portion come into contact with each other even if the outer shape of the winding portion expands in an elliptical shape toward the opening side. It can be done easily. In addition, the outer dimensions can be determined to be the same as those of the conventional ER core, and the cross-sectional area of the outer leg 13 is slightly reduced. Further, by providing a gap between the edge of the inner wall surface 15 and the winding portion that is increased on the opening side side compared to the conventional ER core, heat radiation from the ER core itself or the winding portion with respect to heat generation is improved. Become.

FIG. 4 shows a second embodiment of the present invention, in which the present invention is applied to an ER core. In this figure,
ER core 21, the inner wall surface 15A of the outer legs 13A, an arcuate surface 22 of radius of curvature R _3, are those formed by the chamfered portion 23 of the end portions of the arc surface 22. Other configurations are
This is the same as the first embodiment. In this case, the difference Δb between the edge a of the conventional virtual line L and the inner wall surface 15A showing the outer peripheral surface and the arcuate surface of a curvature radius R ₂ of the concentric central leg 12 is greater amounts.

FIG. 5 shows a third embodiment of the present invention, in which the present invention is applied to an ER core. In this figure,
ER core 31, and contact the inner wall surface 15B of the outer leg 13B, the outer peripheral surface of the central leg portion 12 (the radius R ₁₎ and arcuate surface of the conventional having a concentric radius of curvature R ₂ (phantom line L) The ER core is formed by a plane 32 perpendicular to the longitudinal side surface and an arc surface 33 having a radius of curvature R ₄ continuous on both sides of the plane 32 (where R ₄ > R ₂ ). The center f ₄ of the radius of curvature R ₄ is located on a straight line passing through the center of the central leg 12 and parallel to the longitudinal side face having the opening 16. Other configurations are the same as those in the first embodiment. Also in this case, the radius of curvature R ₂ concentric with the outer peripheral surface of the conventional center leg 12 is also used.
Can be sufficiently ensured between the imaginary line L indicating the circular arc surface and the edge a of the inner wall surface 15B.

FIG. 6 shows a fourth embodiment of the present invention, in which the present invention is applied to an ER core. In this figure,
ER core 41 and contacts the inner wall surface 15C of the outer legs 13C, the outer peripheral surface of the central leg portion 12 (the radius R ₁₎ and arcuate surface of the conventional having a concentric radius of curvature R ₂ (phantom line L) The ER core is formed by a plane 42 perpendicular to the longitudinal side surface and a plane 43 which is continuous on both sides of the plane 42 and is located outside the arc surface of the imaginary line L. These continuous planes 4
2, 43 is in contact with the arc U of large radius of curvature R ₅ than the radius of curvature R _2, the center f ₅ of the radius of curvature R ₅ are longitudinal with the street the opening 16 the center of the central leg 12 It is located on a straight line parallel to the side. In other words, plane 4
2, 43 constitute the inner wall surface approximating to an arc surface of a radius of curvature R ₃ of the first embodiment. Other configurations are the same as those described in the first embodiment.
This is the same as the embodiment. Also in this case, the conventional center leg 12
Virtual line L showing the outer peripheral surface and the arcuate surface of a curvature radius R ₂ of the concentric
Δb between the inner wall surface 15C and the edge a of the inner wall surface 15C can be sufficiently ensured.

FIGS. 7 to 9 show a fifth embodiment of the present invention, in which the present invention is applied to a PQ core. In these figures, the PQ core 51 is composed of a cylindrical central leg 52 having an outer peripheral surface as a circumferential surface, an outer leg 53 wider than this, and a bottom portion 54, and is made of ferrite or the like. It is formed integrally with a magnetic material. Further, on the longitudinal side surface of the PQ core, there is a portion where the outer leg portion 53 is not provided, and this portion is an opening portion 56. The central leg 5
2 is a circumferential surface having a radius R ₁₁ and a distance R between the center of the center leg 52 and the inner wall surface 55 of the outer leg 53.
Constitute the inner wall surface 55 in the arcuate surface of the large radius of curvature R ₁₃ than _12. Center f ₁₃ of the radius of curvature R ₁₃ is located on a straight line parallel to the longitudinal side with the street the opening 56 the center of the central leg 52. For reference, the central leg 52
The arcuate surface of the conventional case having an outer peripheral surface concentric with the radius of curvature R ₁₂ of the illustrated in phantom M. Although illustration is omitted, FIG.
In the center f ₁₃ of the radius of curvature R ₁₃ of the right inner wall surface 55 is symmetrically positioned with respect to the central leg center.

In the fifth embodiment, the edge a of the inner wall surface 55 is retracted by the distance Δe as compared with the conventional virtual line M, and the distance between the edges of the opposing inner wall surface 55 (the opening The opening size (e) of 56) is increased as compared with the conventional case.
For this reason, even if the outer shape of the winding part expands in an elliptical shape toward the opening, there is no danger that the inner wall edge a contacts the winding part, and the winding part can be easily mounted. Further, the outer dimensions can be set to be the same as those of the conventional PQ core, and the cross-sectional area of the outer leg 53 is slightly reduced. In addition, heat dissipation is improved because a gap can be provided between the edge a of the inner wall surface 55 and the winding portion.

FIG. 10 shows a sixth embodiment of the present invention, in which the present invention is applied to a PQ core. In this figure, the PQ core 61 has an inner wall surface 55A of the outer leg 53A.
And an arcuate surface 62 of radius of curvature R _13, those formed by the chamfered portion 63 of the end portions of the arc surface 62. Other configurations are the same as in the fifth embodiment. In this case, the difference Δe between the edge a conventional central leg 52 virtual line M and the inner wall surface 55A showing the arc surface of the outer peripheral surface concentric with the radius of curvature R ₁₂ of the larger amount.

FIG. 11 shows a seventh embodiment of the present invention, in which the present invention is applied to a PQ core. In this figure, the PQ core 71 is provided on the inner wall surface 55B of the outer leg 53B.
And an outer peripheral surface (radius R ₁₁₎ concentric radius of curvature R ₁₂ perpendicular plane 72 in contact and the longitudinal sides of the PQ cores arcuate surface of the conventional (imaginary line M) having a central leg portion 52, is obtained by forming in the arcuate surface 73 of radius of curvature R ₁₄ continuous to both sides of the plane 72 (where, R _14> R _12). Center f ₁₄ of the radius of curvature R ₁₄ is located on a straight line parallel to the longitudinal side with the street the opening 56 the center of the central leg 52. Other configurations are the same as in the fifth embodiment.
Again, the difference Δe between the edge a conventional central leg 52 virtual line M and the inner wall surface 55B showing the outer peripheral surface and the arcuate surface concentric radius of curvature R ₁₂ of the can sufficiently ensured.

FIG. 12 shows an eighth embodiment of the present invention, in which the present invention is applied to a PQ core. In this figure, the PQ core 81 is provided on the inner wall surface 55C of the outer leg 53C.
And an outer peripheral surface (radius R ₁₁₎ and concentric curvature radius arc surface of the conventional with R ₁₂ (phantom line M) in contact and the PQ plane perpendicular 82 to the longitudinal side of the core of the center leg 52, A plane 83 is formed on both sides of the plane 82 and is located outside the arc surface of the virtual line M. These successive planes 82, 83 is in contact with the arc V of large radius of curvature R ₁₅ than the radius of curvature R _12, the center f ₁₅ of the radius of curvature R ₁₅ passes the opening the center of the central leg 52 56 are located on a straight line parallel to the longitudinal side surface. In other words, the plane 82, 83 constitute the inner wall surface approximating to an arc surface of a radius of curvature R ₁₃ of the fifth embodiment. Other configurations are the same as in the fifth embodiment. Again, the difference Δe between the conventional edge a of the inner wall surface 55C and a virtual line M showing the outer peripheral surface and the arcuate surface concentric radius of curvature R ₁₂ of the central leg portion 52 can be sufficiently ensured.

FIGS. 13 to 15 show a ninth embodiment of the present invention, in which the present invention is applied to an RM core. In these figures, the RM core 91 has a cylindrical central leg 92 having an outer peripheral surface as a circumferential surface, an outer leg 93 having a wider width and an outer wall having a polygonal outer surface, and a bottom surface 94. And formed integrally with a magnetic material such as ferrite. Further, a depression 97 is formed in the bottom surface portion 94, and there is a portion where the outer leg portion 93 is not provided on the longitudinal side surface of the RM core, and this portion is an opening portion 96. The outer peripheral surface of the central leg 92 is a circumferential surface having a radius R ₂₁ , and further has a radius of curvature R ₂₃ larger than the distance R ₂₂ between the center of the central leg 92 and the inner wall surface 95 of the outer leg 93. The inner wall surface 95 is constituted by an arc surface. Center f ₂₃ of the radius of curvature R ₂₃ is located on a straight line parallel to the longitudinal side with the street the opening 96 the center of the central leg 92. In addition,
The arcuate surface of the conventional case having an outer peripheral surface concentric with the radius of curvature R ₂₂ of the central leg portion 92 to the reference shown in phantom N. Further, although not shown, the center f ₂₃ of the radius of curvature R ₂₃ of the right inner wall surface 95 in FIG. 13 is in the symmetrical positions with respect to the central leg center.

In the ninth embodiment, the edge a of the inner wall surface 95 is retracted by the distance Δg as compared with the case of the conventional imaginary line N, and the distance between the edges of the opposing inner wall surface 95 (the opening The opening size (g) of 96 is increased as compared with the conventional case.
For this reason, even if the outer shape of the winding part expands in an elliptical shape toward the opening, there is no danger that the inner wall edge a contacts the winding part, and the winding part can be easily mounted. In addition, the outer dimensions can be set to be the same as those of the conventional RM core, and the cross-sectional area of the outer leg portion 93 is only slightly reduced. In addition, heat dissipation is improved because a gap can be provided between the edge a of the inner wall surface 95 and the winding portion.

FIG. 16 shows a tenth embodiment of the present invention.
The case where the present invention is applied to an RM core is shown. In this figure, the RM core 101 has an inner wall surface 95A of the outer leg 93A.
And an arcuate surface 102 of the radius of curvature R _23, those formed by the chamfered portion 103 of the end portions of the arc surface 102. Other configurations are the same as those in the ninth embodiment. In this case, the radius of curvature R ₂₂ concentric with the outer peripheral surface of the conventional center leg 92 is
The difference Δg between the imaginary line N indicating the circular arc surface and the edge a of the inner wall surface 95A becomes a larger amount.

FIG. 17 shows an eleventh embodiment of the present invention.
The case where the present invention is applied to an RM core is shown. In this figure, the RM core 111 has an inner wall surface 95B of the outer leg 93B.
And an outer peripheral surface (radius R ₂₁₎ and in contact with the arcuate surface of the conventional having a concentric radius of curvature R ₂₂ (imaginary line N) and the RM plane perpendicular 112 to the longitudinal side of the core of the center leg 92, Arc surface 11 having a radius of curvature R ₂₄ continuing on both sides of the plane 112
3 (where R ₂₄ > R ₂₂ ). The center f ₂₄ of the radius of curvature R ₂₄ is located on a straight line that passes through the center of the central leg 92 and is parallel to the longitudinal side surface having the opening 96. Other configurations are the same as those in the ninth embodiment. Again, the difference Δg between a conventional edge a of the inner wall surface 95B and the imaginary line N that indicates the arc surface of the outer peripheral surface concentric with the radius of curvature R ₂₂ of the central leg portion 92 can be sufficiently ensured.

FIG. 18 shows a twelfth embodiment of the present invention.
The case where the present invention is applied to an RM core is shown. In this figure, the RM core 121 has an inner wall surface 95C of the outer leg 93C.
And an outer peripheral surface (radius R ₂₁₎ and concentric curvature radius arc surface of the conventional with R ₂₂ (imaginary line N) in contact and the RM plane perpendicular 122 to the longitudinal side of the core of the center leg 92, It is formed by planes 123 and 124 which are continuous on both sides of the plane 122 and are located outside the arc surface of the virtual line N. These successive planes 122, 123, 124 is in contact with the arc W of large radius of curvature R ₂₅ than the radius of curvature R _22, the center f ₂₅ of the radius of curvature R ₂₅ passes the opening the center of the central leg 92 It is located on a straight line parallel to the longitudinal side surface having the portion 96. In other words, the planes 122, 123, 1
24 constitutes a inner wall surface approximating to an arc surface of a radius of curvature R ₂₃ of the ninth embodiment. Other configurations are the same as those in the ninth embodiment. Again, the difference Δg between a conventional edge a of the inner wall surface 95C and the imaginary line N that indicates the arc surface of the outer peripheral surface concentric with the radius of curvature R ₂₂ of the central leg portion 92 can be sufficiently ensured.

FIGS. 19 to 21 show a thirteenth embodiment of the present invention, in which the present invention is applied to an LP core. In these figures, the LP core 131 is composed of a cylindrical central leg 132 whose outer peripheral surface is a circumferential surface, an outer leg 133 wider than this, and a bottom surface 134, and is made of ferrite or the like. It is formed integrally with a magnetic material. Further, on the longitudinal side surface of the LP core, there is a portion where the outer leg portion 133 is not provided, and this portion is the opening portion 136, 137.
It has become. However, in the case of the LP core, when used, the LP core is used such that the opening 137 having a large opening dimension faces the substrate or the like. The outer peripheral surface of the central leg 132 has a radius R _31.
The inner wall surface 135 of the outer leg 133 has a flat surface 138 perpendicular to the longitudinal side surface of the LP core, and a flat surface 138.
8 is obtained by forming in the arcuate surface 139 of the radius of curvature R ₃₃ consecutive. The length of the plane 138 is set equal to the radius R ₃₁ of the center leg 132, the arc surface 139,
Center of central leg 132 and inner wall surface 135 of outer leg 133
Than the distance R ₃₂ between those with a large radius of curvature R _33. Center f ₃₃ of the radius of curvature R ₃₃ is the center leg 1
32 and is located on a straight line parallel to the longitudinal side surface having the opening 137. For reference, the center leg 1
An imaginary line S indicates a conventional circular arc surface having a radius of curvature R32 concentric with the outer peripheral surface of No. ₃₂ . Although illustration is omitted,
Center f ₃₃ of the radius of curvature R ₃₃ of the right inner wall surface 135 is in the symmetrical positions with respect to the central leg around 19.

In the thirteenth embodiment, the edge a of the inner wall surface 135 is retracted by the distance Δh, and the distance between the edge a and the central leg 132 is smaller than that of the conventional virtual line S. Will increase. For this reason, even if the outer shape of the winding part expands in an elliptical shape toward the opening, there is no danger that the inner wall edge a contacts the winding part, and the winding part can be easily mounted. In addition, the outer dimensions can be set to be the same as those of the conventional LP core, and the cross-sectional area of the outer leg 133 is slightly reduced. In addition, the heat radiation property is
This is improved because a gap can be provided between the edge a of the 35 and the winding part.

FIG. 22 shows a fourteenth embodiment of the present invention.
The case where the present invention is applied to an LP core is shown. In this figure, the LP core 141 is provided on the inner wall surface 13 of the outer leg 133A.
5A the long and the length of the plane 138A of the outer peripheral surface radius R ₃₁ of the central leg 132, a plane located outside the circular arc surface of the imaginary line S of the radius of curvature R ₃₂ be continuous to the flat surface 138A 14
2,143. These continuous plane 138A, 142, 143 is in contact with the circular arc X of large radius of curvature R ₃₄ than the radius of curvature R _32, the radius of curvature R
Center f _{34 34} are located on a straight line parallel to the longitudinal side with the street opening 137 the center of the central leg 132. In other words, the planes 138A, 142, 143 are the first
3 constituting the inner wall surface approximating to an arc surface of a radius of curvature R ₃₃ of the embodiment. ). Other configurations are the same as those of the thirteenth embodiment. Again, the difference Δh between the conventional edge a of the inner wall surface 135A and the imaginary line S indicating the arc surface of the outer peripheral surface concentric with the radius of curvature R ₃₂ of the central leg portion 132 can be sufficiently secured.

FIGS. 23 to 25 show a fifteenth embodiment of the present invention, in which the present invention is applied to an EPC core.
In these figures, an EPC core 151 has a central leg portion 152 having an elliptical cylindrical shape (a cross section of an elliptical shape) having an outer peripheral surface that is an elliptical surface (a semicircular surface is connected by a plane). The outer leg portion 153 has a wider width than the outer leg portion 153 and the bottom portion 154, and is integrally formed of a magnetic material such as ferrite. In addition, the outer leg 1 is provided on the longitudinal side surface of the EPC core.
There is a portion where 53 is not provided, and this is the opening 15
6,157. However, in the case of the EPC core, when used, the EPC core is used upright so that the opening 157 having a large opening dimension faces the substrate or the like. Outer peripheral surface portion facing the outer legs 153 of the center leg 152 is a circumferential surface having a radius _{R 41,} the inner wall surface 155 of the outer leg portion 153 the EPC
A plane perpendicular 158 to the longitudinal side of the core, and is formed with an arcuate surface 159 of the radius of curvature R ₄₃ continuous to the flat surface 158. The length of the plane 158 is set equal to the radius R ₄₁ of the semi-circumferential surface of the central leg portion 152. The arc surface 159 has a radius of curvature R ₄₃ larger than a distance R ₄₂ between the center of the semicircular surface of the central leg 152 and the inner wall surface 155 of the outer leg 153. The radius of curvature R ₄₃
Center _{f 43} of the center _{f 43} is the center passes through the center of the radius _{R 41} of the leg portion 152 the located on a straight line parallel to the longitudinal side having an opening 157 (the radius of curvature _{R 43} of the inner
In the direction away from the wall surface 155, is the radius of curvature R _{41 the} center?
Is located on a straight line extending in parallel with the longitudinal direction) . Incidentally, illustrating the arcuate surface of the conventional having a radius of curvature R ₄₂ of the semi-circumferential surface concentric with the central leg 152 to reference virtual line T.
Although not shown, the inner wall surface 155 in FIG.
Center _{f 43} of the radius of curvature _{R 43} of some two places symmetrical position.

In the fifteenth embodiment, the edge a of the inner wall surface 155 is set back by the distance Δj, and the distance between the edge a and the central leg 152 is smaller than that of the conventional virtual line T. Will increase. For this reason, even if the outer shape of the winding part expands toward the opening, there is no danger that the inner wall surface edge a will come into contact with the winding part, and the winding part can be easily mounted. In addition, the outer dimensions can be set to be the same as those of the conventional EPC core, and the cross-sectional area of the outer leg 153 is only slightly reduced. In addition, heat dissipation is improved because a gap can be provided between the edge a of the inner wall surface 155 and the winding portion.

FIG. 26 shows a sixteenth embodiment of the present invention.
The case where the present invention is applied to an EPC core is shown. In this figure, EPC core 161, the inner wall surface 155A of the outer legs 153A, semicircular radii and long plane 158A than R _41, phantom lines be continuous to the plane 158A T of the center leg 152 ( it is obtained by forming in a plane 162 and 163 located outside the arcuate surface of a radius of curvature R _42). These continuous plane 158A, 162 and 163 is in contact with the arc Y of large radius of curvature R ₄₄ than the radius of curvature R _42, the center f ₄₄ of the radius of curvature R ₄₄ is the radius R ₄₁ of the central leg 152 It is located on a straight line passing through the center and parallel to the long side surface having the opening 157. In other words, the planes 158A, 162,
163 constitutes the inner wall surface approximating to an arc surface of a radius of curvature R ₄₃ of the fifteenth embodiment. Other configurations are the same as those described in the first embodiment.
This is the same as the fifth embodiment. Also in this case, the conventional central leg 1
52 difference Δj the edge a of the inner wall surface 155A and the imaginary line T which indicates a half-circumferential surface and the arcuate surface concentric radius of curvature R ₄₂ of the can sufficiently ensured.

In each of the above embodiments, the ER core, PQ
Although the case of the core, the RM core, the LP core, and the EPC core has been described, the present invention is not limited to these embodiments, and may be applied to those having shapes similar to these cores. It is obvious. The central leg may be a regular polygonal column, and the inner wall surface of the outer leg may be a continuous plane of three or more surfaces.

[0034]

As described above, according to the magnetic core of the present invention, at least a part of the inner wall surface of the outer leg portion is constituted by an arc surface having a larger radius of curvature than the conventional case or a surface approximating the arc surface. Even when the winding part is deformed into an elliptical shape by a lead wire, there is no danger that the inner wall edge and the winding part will come into contact with each other. In addition, it is possible to prevent a dielectric breakdown accident and to improve the yield at the time of manufacturing. In addition, since the external dimensions can be set to be the same as those of the conventional product, and the cross-sectional area of the outer leg can be reduced only slightly, the conventional product can be used as it is. Furthermore, by providing a gap between the edge of the inner wall surface of the outer leg and the winding, the heat radiation effect can be improved.

[Brief description of the drawings]

FIG. 1 is a plan view showing a first embodiment of the present invention.

FIG. 2 is a front view of the same.

FIG. 3 is a bottom view of the same.

FIG. 4 is an enlarged plan view of a main part of a second embodiment of the present invention.

FIG. 5 is an enlarged plan view of a main part showing a third embodiment of the present invention.

FIG. 6 is an enlarged plan view showing a main part of a fourth embodiment of the present invention.

FIG. 7 is a plan view showing a fifth embodiment of the present invention.

FIG. 8 is a front view of the same.

FIG. 9 is a bottom view of the same.

FIG. 10 is an enlarged plan view showing a main part of a sixth embodiment of the present invention.

FIG. 11 is an enlarged plan view of a main part showing a seventh embodiment of the present invention.

FIG. 12 is an enlarged plan view of a main part showing an eighth embodiment of the present invention.

FIG. 13 is a plan view showing a ninth embodiment of the present invention.

FIG. 14 is a front sectional view of the same.

FIG. 15 is a bottom view of the same.

FIG. 16 is an enlarged plan view of a main part showing a tenth embodiment of the present invention.

FIG. 17 is an enlarged plan view of an essential part showing an eleventh embodiment of the present invention.

FIG. 18 is an enlarged plan view showing a main part of a twelfth embodiment of the present invention.

FIG. 19 is a front view showing a thirteenth embodiment of the present invention.

FIG. 20 is a side view of the same.

FIG. 21 is a plan view of the same.

FIG. 22 is an enlarged front view of a main part of a fourteenth embodiment of the present invention.

FIG. 23 is a front view showing a fifteenth embodiment of the present invention.

FIG. 24 is a side view of the same.

FIG. 25 is a plan view of the same.

FIG. 26 is an enlarged front view of a main part showing a sixteenth embodiment of the present invention.

FIG. 27 is a plan sectional view showing a conventional example.

FIG. 28 is a perspective view showing a conventional ER core.

FIG. 29 is a perspective view showing a conventional PQ core.

FIG. 30 is a perspective view showing a conventional RM core.

FIG. 31 is a perspective view showing a conventional LP core.

FIG. 32 is a perspective view showing a conventional EPC core.

[Explanation of symbols]

1, 11, 21, 31, 41 ER core 2, 12, 52, 92, 132, 152 Central leg 3, 13, 13A, 13B, 13C, 53, 53A, 5
3B, 53C, 93, 93A, 93B, 93C, 13
3,133A, 153,153A Outer legs 4,14,54,94,134,154 Bottom parts 5,15,15A, 15B, 15C, 55,55A, 5
5B, 55C, 95, 95A, 95B, 95C, 13
5,135A, 155,155A Inner wall surface 22,33,62,73,102,113,139,1
59 Circular surface 23, 63, 103 Chamfer 32, 42, 43, 72, 82, 83, 112, 12
2,123,124,138,138A, 142,14
3,158,158A, 162,163 Plane 51,61,71,81 PQ core 91,101,111,121 RM core 131,141 LP core 151,161 EPC core

Claims (3)

(57) [Scope of request for utility model registration] 1. A magnetic core having a central leg, an outer leg, and a bottom connecting the two legs, and having an opening in which the outer leg is not provided, wherein a center of the central leg and the outer leg are provided. It has a radius of curvature larger than the distance between the inner wall surface of the leg and the center of the radius of curvature is farther from the inner wall surface.
Extending in a direction parallel to the longitudinal direction from the center of the central leg
A magnetic core, wherein the outer leg inner wall surface is constituted by an arc surface located on an elongated straight line or a surface approximating the arc surface. 2. A central leg, an outer leg, and a bottom surface connecting the two legs, and at least a portion of the outer peripheral surface of the central leg facing the outer leg is an arc surface. And a magnetic core having an opening in which the outer leg is not provided, wherein the distance between the center of the first radius of curvature with respect to the arc surface of the central leg and the inner wall surface of the outer leg is having a larger second radius of curvature and the first
In the direction where the center of the radius of curvature of 2 is away from the inner wall surface
Extending from the center of the first radius of curvature parallel to the longitudinal direction
A magnetic core, wherein the outer leg portion inner wall surface is constituted by an arc surface located on a straight line or a surface approximating the arc surface. 3. The surface approximate to the circular arc surface is a continuous multi-plane or a continuous surface composed of a plane and a curved surface.
The described magnetic core.