JP2014096535A - Ferrite core and noise countermeasure component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ferrite core achieving high noise elimination effect, and to provide a noise countermeasure component.SOLUTION: Multiple cable insertion holes 13, 15 are formed in a ferrite core 1. The ferrite core 1 includes a first ferrite material and a second ferrite material having saturation magnetic flux density higher than that of the first ferrite material. In the ferrite core 1, a portion 3 made of the second ferrite material exists between the two adjacent cable insertion holes 13, 15 included in the multiple cable insertion holes 13, 15. A noise countermeasure component 17 includes the ferrite core 1 and a case 19 for storing the ferrite core 1.

Description

  The present invention relates to a ferrite core and a noise countermeasure component.

  Conventionally, a noise countermeasure component including a ferrite core has been used in order to remove electrical noise generated when a current flows through a cable (see, for example, Patent Document 1).

Japanese Patent No. 4789045

  When noise is removed for two cables whose power supply current directions are opposite to each other, as shown in FIG. 12A, the two cables P3 and P5 are formed in the ferrite core P1 in which one cable insertion hole P1A is formed. There is a way to pass. At this time, since the magnetic flux of normal mode noise generated by the cables P3 and P5 is canceled by the ferrite core P1, the noise cannot be removed.

  Also, when removing noise for two cables having opposite directions of the power supply current, as shown in FIG. 12B, the cables P3 and P5 are passed through each of the two ferrite cores P1 and P2. There is a way. At this time, the magnetic flux of the power supply current is taken into the ferrite cores P1 and P2, causing a magnetic flux saturation phenomenon, and the impedance of the ferrite cores P1 and P2 is lowered, so that the effect of removing noise is lowered.

  The present invention has been made in view of the above points, and an object thereof is to provide a ferrite core and a noise countermeasure component having a high noise removal effect.

  The ferrite core of the present invention is a ferrite core in which a plurality of cable insertion holes are formed, and includes a first ferrite material and a second ferrite material having a saturation magnetic flux density higher than that of the first ferrite material. A portion made of the second ferrite material exists between two adjacent cable insertion holes included in the plurality of cable insertion holes.

According to the ferrite core of the present invention, common mode noise and normal mode noise of two cables can be efficiently removed.
In the ferrite core of the present invention, it is preferable that a portion made of the first ferrite material exists around the two cable insertion holes. In this case, the effect of removing common mode noise is even higher.

The first ferrite material preferably has a higher initial permeability than the second ferrite material. In this case, the effect of removing common mode noise is even higher.
It is preferable that a midpoint of a line segment connecting the central axes of the two cable insertion holes is included in a portion made of the second ferrite material. In this case, the effect of removing normal mode noise is even higher.

  The noise countermeasure component of the present invention includes the above-described ferrite core and a case that accommodates the ferrite core. According to the noise countermeasure component of the present invention, common mode noise and normal mode noise of two cables can be efficiently removed.

1 is a perspective view illustrating a configuration of a ferrite core 1. FIG. 6 is a perspective view illustrating a configuration of a noise countermeasure component 17. FIG. 6 is a perspective view illustrating a configuration of a noise countermeasure component 17. FIG. 6 is a side view illustrating the configuration of the noise countermeasure component 17. It is explanatory drawing showing the effect of the ferrite core 1 and the noise countermeasure component 17. FIG. It is explanatory drawing showing the effect of the ferrite core 1 and the noise countermeasure component 17. FIG. It is explanatory drawing showing the effect of the ferrite core 1 and the noise countermeasure component 17. FIG. A to F are explanatory views showing other forms of the ferrite core 1. A to F are explanatory views showing other forms of the ferrite core 1. AC is explanatory drawing showing another form of the ferrite core 1. FIG. A is a perspective view showing the configuration of the ferrite core 1, and B is a front view showing the configuration of the ferrite core 1. A and B are perspective views showing the configuration of a conventional ferrite core.

An embodiment of the present invention will be described.
<First Embodiment>
1. Configuration of Ferrite Core 1 The configuration of the ferrite core 1 will be described with reference to FIG. The ferrite core 1 includes a central portion 3 and a pair of end portions 5 and 7. The end portions 5 and 7 are made of a first ferrite material, and the central portion 3 is made of a second ferrite material. Each of the first ferrite material and the second ferrite material is a ferrite material having the characteristics (representative characteristics) shown in Table 1.

表１に記載されているように、第１のフェライト材は、第２のフェライト材よりも初透磁率が高い。このため、第１のフェライト材は、例えば５０Ω測定系で電圧を１００ｍＶ印可して測定したときのインピーダンスが第２のフェライト材に比較して大きくなる。

As described in Table 1, the first ferrite material has a higher initial magnetic permeability than the second ferrite material. For this reason, the impedance of the first ferrite material is larger than that of the second ferrite material when measured by applying a voltage of 100 mV in a 50Ω measurement system, for example.

  On the other hand, the second ferrite material has a higher saturation magnetic flux density than the first ferrite material. For this reason, for example, even if the second ferrite material takes in a magnetic flux generated from a power supply current having a current value of 2 A or more and the magnetic flux density is increased, the second ferrite material is less likely to be saturated as compared with the first ferrite material, and impedance characteristics Deterioration becomes milder. Therefore, for example, when the current value of the power supply current is 2 A or more, the deterioration of the impedance characteristic is smaller than the deterioration of the impedance characteristic of the first ferrite material, and as a result, at a noise frequency of 0.1 to 10 MHz. Is larger in impedance than the first ferrite material.

  The center part 3 has a rectangular parallelepiped shape. The end portions 5 and 7 have a columnar shape having a substantially U-shaped cross section. That is, a groove 9 having a U-shaped cross section is formed on one surface 5A of the end portion 5 from one end thereof to the opposite end, and one surface 7A of the end portion 7 is formed from one end thereof. A groove 11 having a U-shaped cross section is formed up to the opposite end.

  The central portion 3 and the end portions 5 and 7 are arranged as shown in FIG. 1 and used as the ferrite core 1. That is, the end portion 5 abuts on one surface 3A in the central portion 3, and the end portion 7 abuts on a surface 3B on the opposite side of the surface 3A in the central portion 3. The direction of the end 5 is the direction in which the surface 5A opposes the surface 3A, and the direction of the end 7 is the direction in which the surface 7A opposes the surface 3B. Therefore, the opening of the groove 9 is closed by the surface 3 </ b> A and becomes the cable insertion hole 13. Further, the opening of the groove 11 is closed by the surface 3 </ b> B and becomes a cable insertion hole 15. The axial directions of the cable insertion holes 13 and 15 are both directions orthogonal to the surface 3C (surface adjacent to and orthogonal to the surfaces 3A and 3B) in the central portion 3. Further, the shape and size of the cable insertion holes 13 and 15 are the same in any of the cross sections in the axial direction.

  In the ferrite core 1, the central portion 3 made of the second ferrite material exists between the cable insertion holes 13 and 15. More specifically, the midpoint 16 of the line segment connecting the central axes of the cable insertion holes 13 and 15 is included in the central portion 3. Further, in the periphery of the cable insertion holes 13 and 15, portions other than the central portion 3 are constituted by end portions 5 and 7 made of the first ferrite material.

2. Configuration of Noise Countermeasure Component 17 The configuration of the noise countermeasure component 17 will be described with reference to FIGS. The noise countermeasure component 17 includes the ferrite core 1 and a housing case 19 for housing it. The housing case 19 is a resin case, and includes a first case 21 capable of housing the central portion 3, a second case 23 capable of housing the end portion 5, and a third case capable of housing the end portion 7. Case 25.

  The first case 21 opens the surfaces 3A and 3B when the central portion 3 is accommodated. The second case 23 opens the surface 5A and the inner surface of the groove 9 when the end portion 5 is accommodated. The third case 25 opens the surface 7 </ b> A and the inner surface of the groove 11 when the end portion 7 is accommodated.

  The first case 21 and the second case 23 are rotatably connected by a hinge 27, and the first case 21 and the third case 25 are rotatably connected by a hinge 29. Yes. Therefore, the housing case 19 has a state in which the second case 23 and the third case 25 are opened with respect to the first case 21, as shown in FIG. As shown in FIG. 2, the first case 21 can be in any state of the second case 23 and the third case 25 being closed.

  In the opened state, the ferrite core 1 can be attached to the housing case 19 or the ferrite core 1 can be removed from the housing case 19. In the closed state, the positional relationship between the central portion 3 and the end portions 5 and 7 is as shown in FIG. 1, and the function of the ferrite core 1 can be achieved.

3. The effect which the ferrite core 1 and the noise countermeasure component 17 show | plays The effect which the ferrite core 1 and the noise countermeasure component 17 show | play is demonstrated based on FIGS.

  When the ferrite core 1 is used, as shown in FIG. 5, the first cable 101 can be passed through the cable insertion hole 13 and the second cable 103 can be passed through the cable insertion hole 15. Then, it is assumed that a power supply current in the direction D1 flows through the first cable 101 and a power supply current in the direction opposite to the direction D1 (direction D2) flows through the second cable 103.

  At this time, the magnetic flux due to the power supply current flowing through the first cable 101 (dotted line arrow in FIG. 5) and the magnetic flux due to the power supply current flowing through the second cable 103 (dotted line arrow in FIG. 5) The direction is the same in the (particularly between the cable insertion holes 13 and 15) and the magnetic flux is superimposed, so that the magnetic flux density in that part is increased. On the other hand, at the end portions 5 and 7, the magnetic flux due to the power supply current flowing through the first cable 101 and the magnetic flux due to the power supply current flowing through the second cable 103 cancel each other.

  When common mode noise occurs (when the direction N1 of the noise current flowing through the first cable 101 is the same as the direction N2 of the noise current flowing through the second cable 103), as shown in FIG. The magnetic flux (dotted arrow in FIG. 6) due to the noise current flowing through and the magnetic flux (dotted line arrow in FIG. 6) due to the noise current flowing through the second cable 103 are in the central portion 3 (particularly the cable insertion holes 13, 15). In the portion between the two), the directions are opposite to each other, so that they are canceled out, while the ends 5 and 7 are not canceled out.

  The ferrite core 1 includes end portions 5 and 7 made of a first ferrite material having a high initial permeability, that is, a large impedance, and the end portions 5 and 7 cancel the magnetic flux due to the power source current as described above. In addition, since it is difficult to saturate, a high common mode noise suppression effect can be achieved at the end portions 5 and 7.

  When normal mode noise occurs (when the direction of noise current N1 flowing through the first cable 101 is opposite to the direction of noise current N2 flowing through the second cable 103), as shown in FIG. The magnetic flux due to the noise current flowing through the cable 101 (dotted line arrow in FIG. 7) and the magnetic flux due to the noise current flowing through the second cable 103 (dotted line arrow in FIG. 7) are directions at the ends 5 and 7. Are canceled because they are opposite to each other, and are not canceled in the central portion 3 (particularly, the portion sandwiched between the cable insertion holes 13 and 15).

  The central portion 3 of the ferrite core 1 is made of the second ferrite material that has a high saturation magnetic flux density and is difficult to be saturated by the magnetic flux. Even magnetic flux saturation is difficult. Accordingly, since the deterioration of the impedance characteristics at a noise frequency of 0.1 to 10 MHz is moderated, the impedance is increased at the frequency compared to the case where the central portion 3 is made of the first ferrite material. High normal mode noise suppression effect can be achieved.

As described above, the ferrite core 1 and the noise countermeasure component 17 can exhibit a high noise suppression effect in both common mode noise and normal mode noise.
If not only the end portions 5 and 7 but also the central portion 3 is made of the first ferrite material having a low saturation magnetic flux density, the central portion 3 is saturated by the magnetic flux of the power source current, and normal mode noise is generated. May not be sufficiently suppressed.

  Further, assuming that not only the central portion 3 but also the end portions 5 and 7 are made of a second ferrite material having a low impedance when measured by applying a voltage of 100 mV in a 50Ω measurement system, the end portions 5 and 7 may not sufficiently suppress common mode noise.

  Further, since common mode noise and normal mode noise are noises generated from different causes, both noises may be superimposed and flow to each cable. In such a case, the noise intensity becomes stronger or weaker depending on conditions such as the noise frequency of both.

  In the ferrite core 1 and the noise countermeasure component 17, since the noise suppression effect is enhanced in both the first ferrite material region and the second ferrite material region, noise is suitably suppressed even in the above case. Can do.

3. Different forms of ferrite core 1 (3-1) The first ferrite material and the second ferrite material are not limited to the above, and may have, for example, the characteristics shown in Table 2 or Table 3. Good. Also in this case, the ferrite core 1 has the effects described above. Also in Tables 2 and 3, the second ferrite material has a smaller deterioration in impedance characteristics when the current value of the power supply current is 2 A or more than the deterioration in impedance characteristics of the first ferrite material. As a result, the impedance is larger than that of the first ferrite material at a noise frequency of 0.1 to 10 MHz.

（３−２）フェライトコア１の形状は上記のものには限定されず、例えば、図８Ａ〜Ｆ、図９Ａ〜Ｆ、図１０Ａ〜Ｃのいずれかに示すものであってもよい。なお、これらのフェライトコア１を構成する中央部３、端部５、７は、各図面の紙面に平行ないずれの断面においても、同一の形状及び大きさを有する。これらの形状を有するフェライトコア１も、上述した効果を奏する。
＜第２の実施形態＞
１．フェライトコア１の構成
フェライトコア１の構成を図１１Ａ、Ｂに基づいて説明する。フェライトコア１は、円環状の外周部３１と、その内部に設けられた略Ｙ字状の内周部３３とから成る。外周部３１は第１のフェライト材から成り、内周部３３は第２のフェライト材から成る。第１のフェライト材、及び第２のフェライト材は、それぞれ、上記表１、上記表２、及び上記表３のいずれかに示す特性を有するフェライト材である。

(3-2) The shape of the ferrite core 1 is not limited to the above, and may be, for example, one shown in any of FIGS. 8A to F, FIGS. 9A to F, and FIGS. The central portion 3 and the end portions 5 and 7 constituting the ferrite core 1 have the same shape and size in any cross section parallel to the paper surface of each drawing. The ferrite core 1 having these shapes also has the effects described above.
<Second Embodiment>
1. Configuration of Ferrite Core 1 The configuration of the ferrite core 1 will be described with reference to FIGS. The ferrite core 1 includes an annular outer peripheral portion 31 and a substantially Y-shaped inner peripheral portion 33 provided therein. The outer peripheral portion 31 is made of a first ferrite material, and the inner peripheral portion 33 is made of a second ferrite material. The first ferrite material and the second ferrite material are ferrite materials having the characteristics shown in any one of Table 1, Table 2, and Table 3, respectively.

The holes existing inside the outer peripheral portion 31 are divided into three holes by the inner peripheral portion 33. The three holes are designated as cable insertion holes 35, 37, and 39.
In the ferrite core 1, an inner peripheral portion 33 made of the second ferrite material exists between the cable insertion holes 35 and 37. More specifically, the midpoint of the line segment connecting the central axes of the cable insertion holes 35 and 37 is included in the inner peripheral portion 33. Further, an outer peripheral portion 31 made of the first ferrite material exists around the cable insertion holes 35 and 37.

  In the ferrite core 1, an inner peripheral portion 33 made of the second ferrite material exists between the cable insertion holes 37 and 39. More specifically, the midpoint of the line segment connecting the central axes of the cable insertion holes 37 and 39 is included in the inner peripheral portion 33. An outer peripheral portion 31 made of the first ferrite material exists around the cable insertion holes 37 and 39.

  In the ferrite core 1, an inner peripheral portion 33 made of the second ferrite material exists between the cable insertion holes 39 and 35. More specifically, the midpoint of the line segment connecting the central axes of the cable insertion holes 39 and 35 is included in the inner peripheral portion 33. An outer peripheral portion 31 made of the first ferrite material exists around the cable insertion holes 39 and 35.

In addition, a noise countermeasure component can be manufactured by accommodating the ferrite core 1 of this embodiment in a storage case.
2. Effect of Ferrite Core 1 When the ferrite core 1 is used, the first cable 101 can be passed through the cable insertion hole 35 and the second cable 103 can be passed through the cable insertion hole 37 as shown in FIG. 11B. Then, power supply currents in opposite directions can flow through the first cable 101 and the second cable 103. Note that another cable may be passed through the cable insertion hole 39.

  At this time, the magnetic flux due to the power supply current flowing through the first cable 101 and the magnetic flux due to the power supply current flowing through the second cable 103 are portions 33A located between the cable insertion holes 35 and 37 in the inner peripheral portion 33. Since the directions are the same, the magnetic flux density at that portion is increased. On the other hand, in other portions (including the outer peripheral portion 31) of the ferrite core 1, the magnetic flux generated by the power supply current flowing through the first cable 101 and the magnetic flux generated by the power supply current flowing through the second cable 103 cancel each other.

  When common mode noise occurs (when the direction of the noise current flowing through the first cable 101 is the same as the direction of the noise current flowing through the second cable 103), the magnetic flux generated by the noise current flowing through the first cable 101, The magnetic flux caused by the noise current flowing through the second cable 103 is canceled because the directions are opposite to each other in the portion 33A in the inner peripheral portion 33, and is not canceled in other portions (including the outer peripheral portion 31) in the ferrite core 1.

  The ferrite core 1 includes an outer peripheral portion 31 made of a first ferrite material having a large impedance. Further, as described above, the magnetic flux due to the power supply current is canceled out and hardly saturated in the outer peripheral portion 31. A high common mode noise suppression effect can be achieved.

  Further, when normal mode noise occurs (when the direction of the noise current flowing through the first cable 101 is opposite to the direction of the noise current flowing through the second cable 103), the magnetic flux due to the noise current flowing through the first cable 101 The magnetic flux caused by the noise current flowing through the second cable 103 is not canceled by the portion 33A in the inner peripheral portion 33, but is canceled by the other portions.

  Since the ferrite core 1 includes the inner peripheral portion 33 that has a high saturation magnetic flux density and is not easily saturated by the magnetic flux of the power source current, the inner peripheral portion 33 can exhibit a high normal mode noise suppression effect.

As described above, the ferrite core 1 can exhibit a high noise suppression effect in both common mode noise and normal mode noise.
Further, when the first cable 101 is passed through the cable insertion hole 37 and the second cable 103 is passed through the cable insertion hole 39, or the first cable 101 is passed through the cable insertion hole 39 and the second cable 103 is passed through the second cable 103. Even when the cable 103 is passed, the same effect as described above can be obtained.

In addition, this invention is not limited to the said embodiment at all, and it cannot be overemphasized that it can implement with a various aspect in the range which does not deviate from this invention.
For example, the number of cable insertion holes formed in the ferrite core 1 is not limited to 2 or 3, and may be 4 or more. Moreover, about some cable insertion holes among several cable insertion holes, the part which consists of a 2nd ferrite material may exist between those cable insertion holes.

Further, the ferrite core 1 in the first embodiment may be of an integrated type (one that cannot be divided into a plurality of parts).
In addition, the ferrite core 1 in the first and second embodiments may be made of three or more types of ferrite materials. In that case, two types of ferrite materials selected appropriately among three or more types of ferrite materials can be used as the first ferrite material and the second ferrite material.

DESCRIPTION OF SYMBOLS 1 ... Ferrite core, 3 ... Center part, 3A, 3B, 3C, 5A, 7A ... surface,
5, 7 ... end, 9, 11 ... groove, 13, 15 ... cable insertion hole, 16 ... midpoint 17 ... noise countermeasure part, 19 ... housing case, 21 ..First case,
23 ... 2nd case, 25 ... 3rd case, 27, 29 ... Hinge,
31 ... outer peripheral part, 33 ... inner peripheral part, 33A ... part,
35, 37, 39 ... cable insertion hole, 101 ... first cable,
103 ... second cable

Claims (4)

A ferrite core having a plurality of cable insertion holes,
Including a first ferrite material and a second ferrite material having a saturation magnetic flux density higher than that of the first ferrite material,
A ferrite core, wherein a portion made of the second ferrite material exists between two adjacent cable insertion holes included in the plurality of cable insertion holes.   2. The ferrite core according to claim 1, wherein the first ferrite material has an initial permeability larger than that of the second ferrite material.   3. The ferrite core according to claim 1, wherein a midpoint of a line segment connecting the central axes of the two cable insertion holes is included in a portion made of the second ferrite material. 4. The ferrite core according to any one of claims 1 to 3,
A case housing the ferrite core;
A noise countermeasure component characterized by comprising:

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