JP2529510B2 - High frequency 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 high frequency core applied to a magnetic core such as a transformer or an inductor used in a high frequency region.

[0002]

2. Description of the Related Art Conventionally, in a high frequency core having a structure in which a donut-shaped magnetic material is divided into two in the radial direction, when it is desired to change the magnitude of the inductance, the number of turns of the coil or the gap length is changed, or the number of turns and the gap of the coil are changed. We cope by changing both lengths. And the gap length is
Usually, it is provided so as to be exposed on one of the inner wall and the outer wall, or on both the inner wall and the outer wall, but the position is continuously formed on a plane parallel to the dividing surface of the core. Such an inductance varying means is not limited to the doughnut-shaped magnetic material and is also applicable to the EI type and the EE type.

[0003]

In the above-mentioned prior art, since the core is made by pressing and sintering with a mold, the core generally has an error of ± 25% in inductance. In addition, since the error due to the coil is added, it is ± 25% in the actual transformer and choke coil.
It has the above-mentioned inductance error.

Conventionally, this error has been dealt with by selecting the core, or the error of the transformer or the choke coil has been covered by the circuit design. However, there is a problem in that the cost is high in the selection and the error value tends to be large in the case of the correspondence by the circuit design, so that the circuit design of other parts and the performance of the circuit are affected.

Further, in a core having two or more independent magnetic circuits in the inner space of a doughnut-shaped core and coils are arranged in each magnetic circuit, when the magnetic circuits of the respective coils are separated, conventionally, A metal plate is inserted between the magnetic circuits to separate them. In the case where at least one of the magnetic circuits has a gap, if the gap is formed inside, the separation of the magnetic circuit becomes incomplete, so the gap is exposed to the outside. However, when the gap is exposed to the outside, there is a problem that leakage flux, radiation noise, etc. increase.

Further, in the donut-shaped core, the conventional E
Compared with cores of types such as I type and EE type, the cross-sectional area in which the coil can be wound is small, so copper loss tends to increase,
Therefore, in a choke coil using a donut-shaped core, it is necessary to reduce the gap length of the core and the number of turns of the coil. However, because of this, the range in which the current that flows in the choke coil continuously flows is narrowed, so there is a problem that the output voltage fluctuates significantly when the load is light, especially when there are multiple outputs.

When a metal foil or a sheet-like multi-parallel wire is used for the winding of the donut-shaped core, as shown in FIG. 39, the lead wire 43 and the winding wire 44 are welded to each other at the lead-out portion 45, as shown in FIG. 39 (a in FIG. 39), or spot welding to connect to another conductor ((b) in FIG. 39), or the winding 44 is bent at a right angle and pulled out ((c) in FIG. 39), etc. Therefore, there is a problem that the width of the winding becomes wider than other portions, and the space factor of the winding becomes poor.

FIG. 40 shows the relationship between the space factor and the number of turns of the winding when the metal foil is bent and pulled out. The smaller the number of turns of the winding, the worse the space factor and the copper loss. Will increase. This is a big problem for increasing the switching frequency when the donut-shaped core is used as a transformer.

A first object of the present invention is to provide a high-frequency core whose inductance can be changed without changing the number of turns of the coil and the gap length.

It is a second object of the present invention to provide a high frequency core which does not expose the gap to the outside and allows complete separation of the magnetic circuit.

[0011]

In order to achieve the above object, the present invention has at least one winding accommodating portion having a hollow air core hole at the center and mounting a winding on the outside thereof. In a high frequency core having a groove, at least one opening along the groove is provided in the winding housing groove.

The above object is to make the inner wall or the outer wall of the winding accommodating groove elliptical, or to provide means for changing the height of the inner wall or the outer wall continuously or discontinuously, or the wall thickness of the inner wall or the outer wall. It can also be achieved by partially differentiating.

Further, in order to enhance the effect of varying the inductance, a magnetic material having a magnetic permeability different from that of the core may be arranged in the recess of the inner wall or the outer wall.

[0014]

According to the above-mentioned means, by providing the gap, the range in which the current continuously flows at a light load is widened and the maximum current can be increased, so that a choke coil having a small copper loss can be constructed. .

Further, the inner wall or the outer wall of the winding housing groove is formed into an elliptical shape, or means for changing the height of the inner wall or the outer wall continuously or discontinuously is provided, or the wall thickness of the inner wall or the outer wall is partially formed. The inductance can be changed without changing the number of turns of the coil and the gap length, and the influence of variations in the core can be reduced.

Furthermore, by disposing a magnetic material having a magnetic permeability different from that of the core in the recess of the inner wall or the outer wall of the winding housing groove, leakage magnetic flux and radiation noise can be reduced,
The space factor of the winding can be improved.

[0017]

1 is a plan view showing an embodiment of a high frequency core according to the present invention, and FIG. 2 is a sectional view taken along the line AA 'of the embodiment shown in FIG.

The core in this embodiment is in the shape of a donut and is divided into upper and lower parts in order to house the winding therein. The upper and lower surfaces are closed except for the central part. There is. A hollow air core hole 1 is provided at the center of the upper and lower surfaces, and an inner wall 2 is formed along the contour of the air core hole 1,
An outer wall 3 is formed concentrically with the inner wall 2. A winding housing groove 4 is formed between the inner wall 2 and the outer wall 3 of at least one of the cores, and a semicircular arc-shaped gap (slit) 5 is circumferentially formed on the bottom surface of the winding housing groove 4 to connect the connecting portions 6 to each other. It is provided so as to go around once.

With such a configuration, the inductance characteristic as shown by the solid line in FIG. 3 can be obtained. That is, when the current flowing in the winding is small and the magnetic substance in the connecting portion 6 is not saturated, there is no gap in the connecting portion 6,
Inductance is large (α part). On the other hand, when the current increases, the magnetic substance in the portion of the connecting portion 6 becomes saturated, and the inductance decreases (β portion). When the current is further increased, the magnetic substance in the connecting portion 6 is completely saturated (γ
Part) and the connection part 6 can be regarded as a gap, and the inductance is the same as when the gap is continuous.

By the way, the characteristic indicated by the alternate long and short dash line in the figure is when the core is not provided with a gap (conventional structure), the inductance becomes extremely large when the current value is small, and the current is more than a certain value. It can be seen that the inductance becomes 0 when. As is apparent from this, according to the present invention, the variable width of the inductance is narrowed, but the inductance can be changed without changing the number of windings of the coil or the gap length. The dotted line in the figure shows the inductance characteristic when the connecting portion 6 is a gap in the core of FIG.

4 and 5 are perspective views showing an example of forming the gap 5 in the embodiment of FIG.

In FIGS. 4A and 4B, the gap 5 and the connecting portion 6 are provided in one of the upper core 7 and the lower core 8 (the other is formed into a conventional core shape without an opening portion). In FIG. 5, the gap 5 and the connecting portion 6 are provided in both the upper core 7 and the lower core 8.

FIG. 6 is a perspective view showing the upper core 7 of the second embodiment of the present invention. Here, since the same reference numerals are used for the same components as those in the above-mentioned embodiment, duplicated description will be omitted.

This embodiment is characterized in that a conductor 9 is attached to the upper core 7 having the gap 5 shown in FIG. 4A so as to cover the entire flat surface thereof. In the above-described embodiment, the intermittent gap formed by the gap 5 and the connecting portion 6 is exposed on the surface, and leakage magnetic flux and radiation noise are generated, but in the present embodiment, this can be prevented.

FIG. 7 is a plan view showing the lower core of the third embodiment of the high-frequency core according to the present invention, and FIG. 8 is its BB '.
It is sectional drawing. Also in this embodiment, the same reference numerals are used for the same components as those in the above-mentioned embodiment, and the duplicated description will be omitted.

While the gap 5 shown in FIG. 1 is located on the same radius, the present embodiment is characterized in that the gaps 5 are partially different and are arranged concentrically. In this example, two semi-arcuate gaps 10 having different radii are made to face each other with a length of about half a circumference, and both ends thereof are overlapped with each other, and a connection portion 11 is formed at this portion. The effects obtained by such a configuration are the same as those of the above-described embodiment.

FIG. 9 is a plan view showing the lower core of the fourth embodiment of the present invention, and FIG. 10 is a sectional view taken along the line CC 'of the embodiment of FIG. Also in the present embodiment, the same reference numerals are used for the same components as those in the above-mentioned respective embodiments, and the duplicated description will be omitted.

The present embodiment is characterized in that the outer peripheral surface is a straight circle and the inner peripheral surface (which is also the inner diameter shape of the air core hole 12) is a lower core 14 having an elliptical inner wall 13. . The outer wall 3 is the same as that in the above embodiment. Although only the lower core 14 is shown here, the upper core (not shown) has the same structure and the same outer shape.

FIG. 11 is an exploded perspective view showing an example in which the high-frequency core having the structure of FIG. 10 is combined. 12 and 13 are explanatory diagrams showing the degree of overlap of the inner wall 13 when the lower core 14 and the upper core 15 are relatively rotated.

As shown in FIG. 11, when the center of the lower core 14 and the upper core 15 are aligned with each other and one of them is rotated (actually, the winding is loaded in the winding housing groove 4. However, as shown in FIG. 12 or FIG. 13, the cross-sectional area of the magnetic path changes depending on the overlapping state of the inner wall 13, and the inductance changes according to this cross-sectional area. FIG. 12 shows the case where the cross-sectional area (hatched portion) is the maximum, and FIG. 13 shows the case where the cross-sectional area is the minimum. The larger the overlapping area, the larger the inductance, and the smaller the overlapping area, the smaller the inductance.

FIG. 14 is a plan view showing the lower core of the fifth embodiment of the present invention, and FIG. 15 is a DD 'of the embodiment of FIG.
It is sectional drawing.

The present embodiment has the same shape as the air core hole 1 and the inner wall 2 of the embodiment of FIG. 1, but has an outer wall 16 having an elliptical outer peripheral surface and a right circular inner peripheral surface. However, it is characterized in that the upper surface of the lower core 17 is slightly lower than the upper surface of the outer wall 3. Here, only the lower core 17 is shown, but the upper core (not shown) has the same structure. The operation of this embodiment is the same as that of the embodiment shown in FIG. 9, and a winding (not shown) is loaded in the winding housing groove 4 and the lower core and the upper core are rotated relative to each other to form a magnetic path. The cross-sectional area changes, and the inductance changes according to this cross-sectional area.

FIG. 16 is a plan view showing the lower core of the sixth embodiment of the present invention, and FIG. 17 is an EE 'of the embodiment of FIG.
It is sectional drawing. FIG. 18 is an exploded perspective view showing a state in which the upper core and the lower core are combined.

In this embodiment, as shown in FIG. 17, the inner wall 1 of FIG. 1 is obtained by obliquely cutting the surface of the inner wall 1.
The feature is that the lower core 19 having 8 is used. Also in this case, the upper core (not shown) is also processed as shown in FIG. Then, as shown in FIG. 18, when the lower core 19 and the upper core 20 are faced and overlapped with each other, as shown in FIG. 19, a gap between the facing surfaces of the inner wall 18a of the upper core 20 and the inner wall 18b of the lower core 19 is formed. Becomes the gap 21. With respect to the gap 21, when one of the lower core 19 and the upper core 20 is rotated, the width of the gap 21 changes, and the inductance changes accordingly.

FIG. 20 is a plan view showing the lower core of the seventh embodiment of the present invention, and FIG. 21 is an FF 'of the embodiment of FIG.
It is sectional drawing. FIG. 22 is an exploded perspective view showing a state where the upper core and the lower core are combined.

In this embodiment, the inner wall 22 is provided with an inclined surface on the inner wall in contrast to the inner wall 22 in which upper and lower steps 23 are partially (here, at intervals of 45 °) provided at the upper edge. The lower core 24 is characterized in that its surface height is lower than that of the upper surface of the outer wall 3. Although only the lower core is shown here, the same processing is performed on the upper core 25 as shown in FIG.

In this embodiment, as shown in FIG. 22, when the lower core 24 and the upper core 25 face each other and are stacked, the inner walls 22a, 22b of the upper core 24 and the lower core 25 are arranged as shown in FIG. The cross-sectional area of the magnetic path changes according to the deviation of the step shape (here, every 45 °), and the inductance changes according to this cross-sectional area.

FIG. 24 is a plan view showing the lower core of the eighth embodiment of the present invention, and FIG. 25 is the JJ 'of the embodiment of FIG.
It is sectional drawing.

In this embodiment, as shown in FIG. 25, an inner wall 27 having an outer taper 26 at its upper edge is provided,
Moreover, the lower core 28 is characterized in that its surface height is lower than that of the outer wall 3. In such a configuration, since the inner wall 27 has the taper 26, the gap gradually expands in the radial direction.

The shape of the inner wall 27 is as shown in FIG.
A taper shape, a step shape, a concave surface, a round shape, a composite shape, or the like can be arbitrarily set.

FIG. 27 is a plan view showing the lower core of the ninth embodiment of the present invention, and FIG. 28 is the GG 'of the embodiment of FIG.
It is sectional drawing. FIG. 29 is an exploded perspective view showing a state when the upper core and the lower core are combined.

In the core shown here, two winding housing grooves 29 and 30 are formed concentrically so that two windings can be inserted, and the inner wall 31 of the inner core forming the air core hole 1 and the outside thereof. The outer wall 32, and the magnetic circuit separation groove 3 on the outer side of the outer wall 32.
3, the inner wall 34 of the outer core is erected, and the outer wall 35 of the outer core is erected on the outer side of the inner wall 34. Here, the outer wall 32 is configured to have a gap such that the magnetic circuit separation groove 33 side has a larger gap length than the winding receiving groove 29 side of the inner core. Then, a short ring 38 (shown in FIG. 29) can be fitted into the magnetic circuit separation groove 33. 27 and FIG.
The configuration of the lower core 36 shown in FIG. 8 is also adopted for the upper core 37 shown in FIG.

As shown in FIG. 29, at the time of assembling, the lower core 36 and the upper core 37 are made with the groove sides facing each other.
Are overlapped with each other, and at this time, the short ring 38 is fitted in the magnetic circuit separation groove 33.

FIG. 30 is a schematic sectional view showing an example of the shape of the section in the vicinity of the gap in the embodiment of FIG. (A) is an example in which a step is used instead of the taper, and (b) is an example in which a curved surface is formed.

FIG. 31 is a plan view showing a modification of the embodiment shown in FIG. 27, and FIG. 32 is a sectional view taken along the line HH 'of the core having the structure shown in FIG.

27, the taper is provided on the outer wall 32, whereas the present embodiment is characterized in that the taper is provided on the inner wall 34.

FIG. 33 is a plan view showing the lower core of the tenth embodiment of the present invention, and FIG. 34 is a view of I- of the embodiment of FIG.
It is I 'sectional drawing.

In this embodiment, in addition to the structure shown in FIG.
A characteristic is that the lower core 40 is provided with the winding lead-out holes 39 (two in this embodiment) in a strip shape between the outer core 3 and the outer wall 3 in the radial direction. Here, the width L _W of the winding housing groove 4 in which the winding drawing hole 39 is provided is made wider than the widths L ₁ , L ₂ , and L ₃ of the winding housing grooves of other portions. .

FIG. 35 is an exploded perspective view showing a high frequency core according to an eleventh embodiment of the present invention.

In this embodiment, in addition to the structure shown in FIG. 22, a magnetic body 41 (having a different magnetic permeability from the core) fitted in the recess of the step 23 of each of the lower core 24 and the upper core 25 is provided. However, there is a feature. In this case, as shown in FIG. 36, the magnetic body 41 fits like a wedge into the recesses in the inner walls 22 of the lower core 24 and the upper core 25, respectively.
The lower core 24 and the upper core 25 cannot be rotated relative to each other.

FIG. 37 is an exploded perspective view showing a high frequency core of the twelfth embodiment of the present invention.

In this embodiment, the magnetic body 41 of the above embodiment is vertically divided into two, and the inner wall 22 of the lower core 24 and the upper core 25 is divided.
It is characterized in that the magnetic body 42 that can be individually fitted into each of the recesses is formed. That is, as shown in FIG. 38, the lower core 24 and the upper core 25 are allowed to freely rotate with each other, and the magnetic permeability of the magnetic body 42 changes in accordance with the rotation, thereby changing the inductance. . According to the examples of FIGS. 35 and 36, it is possible to improve the space factor of the winding while reducing the leakage magnetic flux and the radiation noise.

[0053]

Since the present invention is configured as described above, it has the following effects.

In the high frequency core according to claim 1, a high frequency core having a hollow air-core hole at the center and at least one winding housing groove for mounting a winding on the outside thereof, Since the gap formed by at least one opening along the groove is provided in the groove of the winding accommodating portion, the range in which the current continuously flows at a light load can be widened and the maximum current can be increased, and the choke coil with a small copper loss can be obtained. It becomes possible to configure such as.

In the high frequency core according to the present invention, a hollow core hole is formed in the center, and at least one winding housing groove for mounting a winding is provided outside the hollow core hole . Since the inner wall or outer wall of the winding housing groove has an elliptical shape, by rotating one of the cores, the optimum inductance can be obtained without changing the number of turns of the coil and the gap length.

In the high frequency core according to claims 3, 4, and 5, a hollow core hole is provided at the center, and at least one winding housing groove for mounting the winding is provided outside thereof. In the high frequency core described above, means for changing the height on the surface of the inner wall or the outer wall of the winding housing groove, specifically,
Since a means for changing the height continuously or discontinuously is provided,
By rotating one of the cores, the optimum inductance can be obtained without changing the number of turns of the coil and the gap length.

In the high frequency core of the sixth aspect, since the magnetic material having a magnetic permeability different from the magnetic permeability of the core is disposed in the recess of the inner wall or the outer wall, the leakage flux and the radiation noise are reduced and the winding The space factor can be improved.

In the high frequency core of claim 7, the center is
In a high frequency core having a hollow core hole and having at least one winding housing groove for mounting a winding on the outside thereof, the wall thickness of the inner wall or the outer wall of the winding housing groove is Since they are partially different, by rotating one of the cores, the optimum inductance can be obtained without changing the number of turns of the coil and the gap length.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment of a high frequency core according to the present invention.

FIG. 2 is a sectional view taken along the line AA ′ of the embodiment of FIG.

FIG. 3 is an inductance characteristic diagram obtained by the embodiment of FIG.

FIG. 4 is a perspective view showing an example of forming a gap in the embodiment of FIG.

5 is a perspective view showing another example of forming the gap of the embodiment of FIG. 1. FIG.

FIG. 6 is a perspective view showing a lower core according to a second embodiment of the present invention.

FIG. 7 is a plan view showing a lower core of a third embodiment of the high-frequency core according to the present invention.

8 is a sectional view taken along line BB ′ of the embodiment of FIG.

FIG. 9 is a plan view showing a lower core of a fourth embodiment of the present invention.

10 is a sectional view taken along the line CC ′ of the embodiment of FIG.

11 is an exploded perspective view showing an example in which the high-frequency core having the configuration of FIG. 10 is combined.

12 is an explanatory diagram showing the degree of overlap of the inner wall when the lower core and the upper core are relatively rotated in the embodiment of FIG.

13 is an explanatory diagram showing another example of the degree of overlap of the inner walls when the lower core and the upper core are relatively rotated in the embodiment of FIG.

FIG. 14 is a plan view showing a lower core of a fifth embodiment of the present invention.

FIG. 15 is a sectional view taken along the line DD ′ of the embodiment shown in FIG.

FIG. 16 is a plan view showing a lower core of a sixth embodiment of the present invention.

FIG. 17 is a sectional view taken along line EE ′ of the embodiment of FIG.

FIG. 18 is an exploded perspective view showing a situation in which the upper core and the lower core are combined in the embodiment of FIG.

FIG. 19 is an explanatory diagram showing a gap change due to core rotation in the embodiment of FIG.

FIG. 20 is a plan view showing a lower core of a seventh embodiment of the present invention.

21 is a cross-sectional view taken along the line FF ′ of the embodiment of FIG.

22 is an exploded perspective view showing how the upper core and the lower core are combined in the embodiment of FIG. 20. FIG.

FIG. 23 is an explanatory diagram showing a gap change when the core is rotated in the embodiment of FIG. 20.

FIG. 24 is a plan view showing a lower core of an eighth embodiment of the present invention.

25 is a sectional view taken along the line JJ ′ of the embodiment of FIG.

26 is a cross-sectional view showing another example of the shape of the inner wall in FIG.

FIG. 27 is a plan view showing the lower core of the ninth embodiment of the present invention.

28 is a sectional view taken along the line GG ′ of the embodiment of FIG. 27.

29 is an exploded perspective view showing how the upper core and the lower core are combined in the embodiment of FIG. 27. FIG.

30 is a schematic cross-sectional view showing an example of the shape of the cross section in the vicinity of the gap according to the embodiment of FIG. 27.

FIG. 31 is a plan view showing a modification of the embodiment of FIG. 27.

32 is a sectional view taken along the line HH 'of the embodiment of FIG.

FIG. 33 is a plan view showing the lower core of the tenth embodiment of the present invention.

34 is a cross-sectional view taken along the line II ′ of the embodiment of FIG. 33.

FIG. 35 is an exploded perspective view showing a high-frequency core according to an eleventh embodiment of the present invention.

FIG. 36 is an explanatory diagram showing the overlapping state of magnetic bodies of the embodiment of FIG. 36.

FIG. 37 is an exploded perspective view showing a high-frequency core according to a twelfth embodiment of the present invention.

FIG. 38 is an explanatory diagram showing the overlapping state of magnetic bodies of the embodiment of FIG. 37.

FIG. 39 is a plan view showing a configuration of a winding lead-out portion of a conventional high frequency core.

FIG. 40 is a characteristic diagram showing the relationship between the space factor and the number of turns of the winding when the metal foil is bent and pulled out.

[Explanation of symbols]

 1 air core hole 2,13,18,22 inner wall 3,16,32,35 outer wall 4 winding housing groove 5,10,21 gap 6,11 connecting portion 7,15,20,25 upper core 8,14, 17, 19 Lower core 9 Conductor 12 Air core hole 23 Steps 24, 28 Lower core 26 Taper 27, 31, 34 Inner wall 29, 30 Winding housing groove 33 Magnetic circuit separation groove 36, 40 Lower core 37 Upper side Core 38 Short ring 39 Winding hole 41, 42 Magnetic material

Claims (7)

(57) [Claims] 1. A high frequency core having a hollow air core hole at the center and at least one winding housing groove for mounting a winding on the outside thereof, in a winding housing groove. A high frequency core, wherein a gap is provided by at least one opening along the groove. 2. A high frequency core having a hollow core hole at the center and at least one winding housing groove for mounting a winding on the outside thereof, wherein an inner wall of the winding housing groove is provided. Alternatively, at least one of the outer walls has an elliptical shape, which is a high-frequency core. 3. A high frequency core having a hollow air core hole at the center and at least one winding housing groove for mounting a winding on the outside thereof, wherein an inner wall of the winding housing groove is formed. Alternatively, a high-frequency core characterized in that means for changing the height is provided on at least one surface of the outer wall. 4. The high frequency core according to claim 3, wherein the means for changing the height is continuously provided. 5. The high frequency core according to claim 3, wherein the means for changing the height is provided discontinuously. 6. The high frequency core according to claim 2, wherein a magnetic material having a magnetic permeability different from the magnetic permeability of the core is disposed in the recess of at least one of the inner wall and the outer wall. 7. A high frequency core having a hollow air-core hole at the center and at least one winding housing groove for mounting a winding on the outside thereof, wherein an inner wall of the winding housing groove is provided. Alternatively, a high frequency core characterized in that the thickness of at least one of the outer walls is partially different.