JPH0349380Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a magnetic core suitable for constructing a coil device such as a small-sized, large-capacity switching power supply transformer.

<Prior Art> In recent years, with the advancement of computers, their terminal devices, office equipment, etc., there has been a need for small, lightweight, thin, and large-capacity switching power supplies. In making switching power supplies smaller and lighter, the most important point is to reduce the weight and size of transformers, which take up a large amount of space and weight, and especially of the magnetic cores that make up the transformers. FIG. 6 is a plan view of a conventional magnetic core of this type, FIG. 7 is a front view thereof, and FIG. 8 is a rear view thereof.
a middle leg part 2 having a circular cross section and erected at the center of the
Two outer legs 3 and 4 stand along the outer periphery of the bottom plate 1 at intervals of d ₁ and d ₂ so as to surround this middle leg 2 from both sides in the diametrical direction. , is an E-shaped magnetic core that is integrally connected as a ferrite molded body. Arrangement interval d ₁ , d ₂ between the two outer legs 3 and 4
Both side end surfaces 101, 1 of the bottom plate portion 1 generated corresponding to
One side end surface 101 of 02 is provided with a semicircular arc-shaped recess 103 that contacts the outer circumferential surface of the middle leg section 2, and the other side end surface 102 is made to face so that the outer circumferential surface of the middle leg section 2 comes into contact with it. be.

In order to construct a transformer or the like using the above-mentioned magnetic core, for example, as shown in FIG. While inserting the coil bobbin 6,
Assemble by matching. Note that an assembly structure may be adopted in which one of the magnetic cores A and B is a flat I-shaped magnetic core.

<Problem to be solved by the invention> The conventional magnetic core shown in FIGS. 6 to 8 can draw out the ends of the winding 5 in multiple directions through the semicircular arc-shaped recess 103 formed from the side end surface 101. Therefore, the winding terminal drawing process is easy. However, the following problems arose.

(A) Since the recess 103 has a semicircular shape and its circumference is connected to the outer peripheral surface of the middle leg 2, as shown in FIG.
Even if a slight variation ΔR occurs in the radius _R1 of 3, the side end surface 101 of the bottom plate part 1 forming the recessed part 103 will come off from the outer peripheral surface of the middle leg part 2, or As shown in the figure, a situation occurs in which the wire is connected in the middle of the outer circumferential surface. For this reason, variations occur in the connection portion between the bottom plate portion 1 and the middle leg portion 2 formed by the recessed portion 103,
There was a problem in that the flow of magnetic flux φ from the outer legs 3 and 4 through the bottom plate 1 to the middle leg 2 was affected and the characteristics varied.

(B) Depending on the relative positional relationship or size between the middle leg part 2 and the outer leg parts 3 and 4, the recess 103
There was also the problem that it became difficult to form the magnetic flux so as to be in contact with the outer circumferential surface of the middle leg portion 2, resulting in poor magnetic flux flow. For example, as shown in FIG. 11, the outer diameter D ₁ of the middle leg 2 and the outer leg 3
If the difference between the inner diameter D of 4 and ₂ becomes large,
This makes it difficult to make the recess 103 continuous with the outer peripheral surface of the middle leg portion 2.

(C) The edge of the bottom plate 1 is sharp. Because of the edges, the edges were likely to be damaged or chipped during die cutting. Further, the press molding pressure is not sufficiently applied to the ridge portion, and the press pressure and packing density tend to be uneven. In this type of magnetic core, the magnetic flux flowing from the outer legs 3 and 4 through the bottom plate 1 to the middle leg 2, or the magnetic flux flowing in the opposite direction, passes through almost the entire area of the bottom plate 1. Therefore, the bottom plate portion 1 forms a magnetic path with no difference in weight or weight up to the ridge portion. Therefore, if damage, chipping, or uneven press pressure or packing density occurs at the edge of the bottom plate 1, which is part of the magnetic path, the magnetic properties will vary greatly, resulting in a significant drop in performance. This results in increased loss and heat generation.

(D) The edge of the bottom plate 1 is sharp. Because it is an edge, it becomes difficult for the molded product to separate from the press mold. For this reason, not only does the removal work become troublesome, but also chipping and damage occur at the edge portions, resulting in poor product performance and a decrease in yield. Further, problems such as damage to the mold and shortened lifespan also occur.

(E) Edges are sharp. Because of the edges, it is difficult to maintain the ridges in an ideal orthogonal state or in a straight ridgeline. This may cause problems in combination with the coil bobbin.

(F) The bending radius of the winding end at the edge becomes larger, and coil devices such as transformers using this magnetic core become larger.

Therefore, the object of this invention is to solve the above-mentioned conventional problems, to improve and stabilize the flow of magnetic flux through the connecting part between the bottom plate part and the middle leg part, and to create a magnetic core with little variation and good characteristics. In addition, the bottom plate part and its side end surfaces prevent chipping and damage at the ridge corners that should be formed, and the press molding pressure and filling density are made uniform.
An object of the present invention is to provide a magnetic core that prevents variations in magnetic properties and improves performance and yield.

<Means for Solving the Problems> In order to solve the above-mentioned problems, the present invention includes a bottom plate part, a middle leg part erected on one surface of the bottom plate part, and a middle leg part along the outer periphery of the bottom plate part. two outer leg sections that are erected on both sides of the leg section with a space between them; and two outer leg sections that are erected at intervals on both sides of the leg section, and the direction in which the bottom plate section faces each other corresponds to the distance between the two outer leg sections. In the magnetic core, a recess reaching the outer circumferential surface of the middle leg is provided on one end face of both end faces formed on the side, and the outer circumferential face of the middle leg is exposed on the other end face, The end surface of the bottom plate is formed in a straight or broken line shape from the opposing edge of the outer leg toward the outer circumferential surface of the middle leg, and the end surface of the bottom plate is formed in a straight line or a broken line, and faces the outer circumferential surface of the middle leg. The other side end surface of the bottom plate portion has an inclined surface that slopes toward the one side of the bottom plate portion, and the middle leg portion has an outer peripheral surface in contact with the other side end surface and a continuous portion thereof. It is characterized in that it is arranged so that a discontinuous portion dividing the inclined surface into two is generated.

<Function> When the recess formed on one side end surface of the bottom plate is directed from the opposing edges of the two outer legs toward the outer peripheral surface of the middle leg, the side end surface of the bottom plate becomes straight or broken. When formed in this way, the side end surface of the bottom plate part forming the recess and the middle leg part are connected in a predetermined relationship depending on the shape, dimensions, etc. of each part, and the flow of magnetic flux through this connection part is improved. At the same time, it is possible to stabilize and improve characteristics, and at the same time, eliminate variations.

The other end surface of the bottom plate facing the outer circumferential surface of the middle leg has an inclined surface that slopes toward one side of the bottom plate, so that the molded product can be easily released from the press mold. At the same time, the occurrence of chipping or damage at the edge portions is prevented.

In addition, since the inclined surface receives the press pressure on the surface,
The press molding pressure is now sufficiently distributed,
Press molding pressure and packing density are made uniform.

Therefore, variations in the magnetic properties of the bottom plate portion, which occupies an important position as a magnetic path, are prevented, and performance and yield are improved.

Furthermore, by preventing chipping and breakage, and making the press pressure and packing density uniform, the bottom plate and both end faces intersect in a shape close to the ideal, allowing for smooth combination with the coil bobbin. . Also, damage to the mold is prevented and the life of the mold is extended. Moreover, the end of the winding can be bent along the inclined surface and the bending radius can be reduced.

Since the middle leg portion is disposed such that its outer circumferential surface is in contact with the other end surface of the bottom plate portion, its shape is reduced.
Moreover, since the middle leg is arranged so that a discontinuous part that divides the slope into two is created in the continuous part with the other side end surface, the slope is provided and the outer peripheral surface of the middle leg is Even though it is provided so as to be in contact with the bottom plate, the cross-sectional shape of the middle leg at the part connected to the bottom plate portion is preserved to be the original cross-sectional shape without being reduced in cross-sectional area by the inclined surface.
For this reason, the flow of magnetic flux entering the middle leg through the bottom plate from both sides of the middle leg and exiting from the middle leg to the bottom plate becomes smooth, improving magnetic efficiency and improving characteristics. Become good.

<Example> Fig. 1 is a plan view of a magnetic core according to the present invention, Fig. 2 is a front view thereof, and Fig. 3 is a rear view thereof.
FIG. 4 is a side sectional view taken along line A ₁ -A ₁ in FIG. 3. In the figures, the same reference numerals as in FIGS. 6 to 8 indicate the same components. The feature different from the conventional example shown in FIGS. 6 to 8 is that the two outer legs 3 and 4 face each other with intervals d ₁ and d ₂ in between.
Of the opposing edges 31-41 and 32-42, the side end surfaces 104 and 105 of the bottom plate part 1 are formed in a straight line from the opposing edges 31 and 41 toward the outer peripheral surface of the middle leg part 2, and this straight line A recess 103 is formed by side end surfaces 104 and 105 having a shape. The side end surfaces 104 and 105 of the bottom plate part 1 are connected to the outer circumferential surface _{of the middle leg part 2 with a distance d 3 between} them. exposed inside.

With the above-described structure, even if there are variations in the shape and formation position of the side end surfaces 104 and 105 of the bottom plate part 1 that form the recessed part 103, the distance _d3 will only change slightly, and the outer leg part The influence on the flow of magnetic flux φ from 3 and 4 through the bottom plate portion 1 to the middle leg portion 2 can be almost ignored. Therefore, a highly reliable magnetic core with small characteristic fluctuations can be obtained.

Furthermore, even if the relative positional relationship or size between the middle leg part 2 and the outer leg parts 3 and 4 changes,
By changing the lengths of the side end surfaces 104, 105 accordingly, the side end surfaces 104, 105 can be connected to the outer peripheral surface of the middle leg portion 2 in a predetermined state, and the flow of magnetic flux can be maintained in a good state.

The other side end surface 102 of the bottom plate part 1 is provided with an inclined surface 108 that slopes toward one surface 106 of the bottom plate part 1. When such an inclined surface 108 is provided, the other end surface 102 has a chamfered shape due to the inclined surface 108, resulting in a sharp. Since the edge part disappears and becomes an obtuse edge, there will be no damage to the winding terminal, improving product performance and yield, and improving the release of the molded product from the press mold, making it easier to remove the mold. The work is facilitated, chipping and breakage at the edge angles are prevented, product performance and yield are improved, damage to the mold is prevented and the mold life is extended, and there is an inclined surface 108. This allows the press molding pressure to be sufficiently applied to the edge portion, making the press pressure and packing density uniform, improving dimensional accuracy, and improving magnetic properties, among other advantages.

In the embodiment, the side end surfaces 104 and 105 of the bottom plate 1 forming the recess 103 also include one surface 10 of the bottom plate 1.
Since a planar or curved inclined surface 107 is provided which slopes toward the 6th side, the side end surfaces 104, 1
05 can also provide the same effects as described above, and a more excellent magnetic core as a whole can be obtained.

The middle leg portion 2 is arranged such that its outer circumferential surface contacts the other end surface 102 and a discontinuous portion 201 that bisects the inclined surface 108 is formed in the continuous portion thereof. In this way, the middle leg portion 2 has an outer circumferential surface that is connected to the other end surface 1 of the bottom plate portion 1.
02, the shape is small. Moreover, the middle leg portion 2 has the other side end surface 102.
A discontinuous part 20 that divides the slope into two parts in the continuous part with
1 occurs, so the inclined surface 1
08 and the outer circumferential surface of the middle leg part 2 is provided so as to be in contact with the other end surface 102, the cross-sectional shape of the middle leg part 2 at the part connected to the bottom plate part 1 is not formed by the inclined surface 108. The original cross-sectional shape is preserved without any reduction in cross-sectional area. Therefore, centering on the middle leg, the magnetic flux entering the middle leg from both sides through the bottom plate 1 and the magnetic flux exiting from the middle leg 2 to the bottom plate 1 flow smoothly, improving magnetic efficiency. , the characteristics become better.

Furthermore, in this embodiment, the height of the outer legs 3, 4 is
H ₁ is made larger than the height H ₂ of the middle leg part 2, and the height h ₁ is approximately equal to the height H ₂ of the middle leg part 2 at the opposing edges 31, 41 of these outer legs 3, 4. , and the step surface 3 whose distance d ₄ is equal to or slightly larger than the outer diameter D ₁ of the middle leg 2
3 and 43 are provided respectively.

The reason why the outer legs 3 and 4 are formed higher than the middle leg 2 is that in the assembly structure as explained in FIG.
This is to form a magnetic gap on the tip surfaces of the middle leg portions 2-2 of the two magnetic cores A and B. The dimensions of the magnetic gap must be controlled with high precision in order to obtain predetermined magnetic properties, and generally the distal end surface of the middle leg portion 2 is polished to maintain its precision. In this case, if there are stepped surfaces 33, 43 as described above, the polishing knife can be moved over the stepped surfaces 33, 43, so especially when polishing a large number of magnetic cores side by side, This work can be done efficiently.

Another example of the other side end surface 102 forming the recess 103 is, for example, as shown in FIG.
04 and 105 into two straight parts 104a, 10
4b, 105a, and 105b may be connected in the form of a broken line. In the embodiment of FIG.
Although the concave portion 103 has a convex bent line shape, the concave portion may have a concave line shape conversely.

<Effects of the invention> As described above, according to the invention, the following effects can be obtained.

(a) A concave portion formed on one side end surface of the bottom plate portion is moved from the opposing edges of the two outer legs toward the outer circumferential surface of the middle leg so that the side end surface of the bottom plate portion has a straight or broken line shape. Therefore, the side end surface of the bottom plate part forming the recess and the middle leg part are connected in a predetermined relationship depending on the shape and dimensions of each part, and the magnetic flux passing through this connection part is It is possible to improve the flow and stabilize it at the same time, and provide a magnetic core with good characteristics and less variation in characteristics.

(b) The other end surface of the bottom plate facing the outer peripheral surface of the middle leg has an inclined surface that slopes toward one side of the bottom plate, so that it is sharp. The edge part disappears and becomes an obtuse edge, which prevents damage to the winding terminal, improves product performance and yield, and improves the release of the molded product from the press mold, making it easier to remove the mold. This will improve product performance and yield by preventing chipping and breakage, will prevent mold damage and extend mold life, and will ensure sufficient press forming pressure. Advantages include uniform press pressure and packing density, improved dimensional accuracy, and improved magnetic properties.

(c) Since the middle leg is arranged so that its outer circumferential surface is in contact with the other end surface of the bottom plate, the shape is small.

(d) The middle leg has two sloped surfaces in the part connected to the other end surface.
Since the arrangement is such that there is a discontinuous part that separates the bottom plate, even though the inclined surface is provided and the outer circumferential surface of the middle leg is in contact with the other side end surface, the part that is continuous with the bottom plate part is The cross-sectional shape of the middle leg is preserved as the original cross-sectional shape without being reduced in cross-sectional area by the inclined surface. For this reason, the flow of magnetic flux entering the middle leg through the bottom plate from both sides of the middle leg and exiting from the middle leg to the bottom plate becomes smooth, improving magnetic efficiency and improving characteristics. Become good.

[Brief explanation of the drawing]

FIG. 1 is a plan view of the magnetic core according to the present invention, FIG. 2 is a front view thereof, and FIG. 3 is a rear view thereof.
Figure 4 is a sectional view taken along line A ₁ - A ₁ in Figure 3;
FIG. 5 is a plan view of another embodiment of the magnetic core according to the present invention, FIG. 6 is a plan view of a conventional magnetic core of this type,
Figure 7 is a front view of the same, Figure 8 is a rear view of the same, Figure 9 is a sectional view of a transformer using a conventional magnetic core, and Figures 10 and 11 explain the problems with the conventional magnetic core. It is a diagram. DESCRIPTION OF SYMBOLS 1...Bottom plate part, 2... Middle leg part, 3, 4... Outer leg part, 103... Recessed part, 104, 105... Side end surface.

Claims (1)

[Claims for Utility Model Registration] (1) A bottom plate part, a middle leg part erected on one surface of the bottom plate part, and spaced apart parts on both sides of the middle leg part along the outer periphery of the bottom plate part. one side of both end surfaces of the bottom plate portion that are formed in opposing directions, with two outer leg portions that are erected in series, and that correspond to the interval between the two outer leg portions; In a magnetic core in which an end face is provided with a recess that reaches the outer peripheral surface of the middle leg, and the other end face faces the outer peripheral face of the middle leg, the recess extends from the opposing edges of the two outer legs. An end surface of the bottom plate section is formed in a straight line or a broken line when facing the outer circumferential surface of the middle leg section, and the other end surface of the bottom plate section faces the outer circumferential surface of the middle leg section. has an inclined surface that slopes toward the one surface side of the bottom plate portion, and the middle leg portion has an outer circumferential surface that touches the other side end surface and a continuous portion thereof that has an integral part that bisects the inclined surface. A magnetic core characterized in that it is arranged so that a continuous portion occurs. (2) The end surface of the bottom plate formed in a straight line or a broken line has an inclined surface that slopes toward the one side of the bottom plate. The magnetic core described in . (3) the outer leg is formed higher than the middle leg;
The opposing edge on the side of the recess is provided with a stepped surface having a height substantially equal to the tip surface of the middle leg and an interval equal to or slightly larger than the outer diameter of the middle leg. Scope of claim for utility model registration No. 1
The magnetic core according to item 1 or 2. (4) The magnetic core according to any one of claims 1, 2, or 3, wherein the bottom plate part, the middle leg part, and the outer leg part are made of a ferrite molded body. . (5) The middle leg has a circular cross-sectional shape in a plane perpendicular to the axis.
The magnetic core described in any of the paragraphs.