Ferrite core powder and ferrite core

Description

[Technical field]

[0001] The present invention relates to a powder for ferrite cores and a ferrite core, and more particularly to a powder for ferrite cores and a ferrite core that are mixed with a flexible resin. [Background technology]

[0002] Patent Document 1 discloses a ferrite core that has excellent electromagnetic properties and improved electromagnetic conductivity. It is described that the ferrite core is produced by a process comprising the steps of preparing a ferrite raw material, adding a carbon material to the ferrite raw material, and sintering the ferrite raw material to which the carbon material has been added to produce the ferrite core. core has a rigid cylindrical shape, and therefore, it is assumed that its inner diameter is uniquely determined and fixed. DISCLOSURE OF THEINVENTION [Problem to be solved by the invention]

[0003] It is known that the impedance of a ferrite core is proportional to the effective cross-sectional area Ae through which the magnetic flux passes, and inversely proportional to the effective magnetic path length Le through which the magnetic flux flows. Therefore, the larger the cylindrical outer diameter of a ferrite core is made to increase the effective cross-sectional area Ae, and the smaller the cylindrical inner diameter is made to decrease the effective magnetic path length Le, the more effectively it can eliminate noise.

[0004] However, as already mentioned, the ferrite core described in Patent Document 1 has a rigid cylindrical shape, and its inner diameter is presumably uniquely determined and standardized, so it is physically difficult to reduce the inner diameter of the cylinder.

[0005] In that case, to effectively eliminate noise, the outside diameter of the cylinder would have to be increased to increase the effective cross-sectional area Ae, but this would require the use of ferrite. core However, there is a drawback in that the size of the device becomes large.

[0006] Therefore, an object of the present invention is to provide a ferrite core whose ferrite core body does not have hardness and a powder for ferrite cores suitable for such ferrite cores. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention provides A ferrite core containing a powder for ferrite cores and a flexible resin serving as a binder for the powder for ferrite cores in a ratio of 40 wt%:60 wt% to 55 wt%:5 wt%, The ferrite core powder is a mixture of ferrite and pulverized ore containing at least silicon as one of its main components in a ratio of 85wt%:15wt%-99wt%:1wt%.

[0008] The ferrite and the pulverized material each preferably have a primary particle size of 10 μm or less.

[0009] The ferrite core body is strip-shaped, a first end having a through hole; A second end portion that is passed through the through hole a plurality of times while the ferrite core body is wound around a winding object; a trunk portion having a holding portion that holds the ferrite core body in a wound state around a winding target; It can also be provided with:

[0010] the holding portion has a plurality of protrusions, any one of which is adapted to engage with an edge of the through hole, The pitch p of each of the protrusions may correspond to the thickness T of the body portion.

[0011] the holding portion has a plurality of protrusions, any one of which is adapted to engage with an edge of the through hole, The pitch p of each of the protrusions may be based on the thickness T of the body portion.

[0012] The through hole has a distal cavity and one or more proximal cavities adjacent to each other, the holding portion has a plurality of protrusions protruding from the body portion, any one of which is engaged with an edge of the through hole, The length x1 of the tip cavity in the longitudinal direction corresponds to the width X1 of the body portion, The longitudinal length x2 of the base end cavity corresponds to the width X2 obtained by adding the width X1 of the body portion to the total height 2h of the protrusions on each side, It is preferable that the length y of each of the distal end cavity and the proximal end cavity in the short side direction corresponds to the thickness T of the body portion.

[0013] The ferrite core body may be covered with tape after being wound around the object to be wound.

[0014] The object to be wrapped may be an electric wiring cable.

[0015] The ferrite core body may be plate-shaped and covered with tape when attached to an object to which it is attached.

[0016] Furthermore, the powder for ferrite cores of the present invention is The ferrite core is Ferrite and crushed ore containing at least silicon as one of its main components are mixed in a ratio of 85wt%:15wt% to 99wt%:1wt%. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In each drawing, the same parts are given the same reference numerals. Note that in this specification, expressions such as top, bottom, left, right, front, back, etc. are relative and not absolute.

[0018] (Embodiment 1) Fig. 1 is an explanatory diagram of a ferrite core 100 according to a first embodiment of the present invention. Fig. 1(a) shows a plan view, Fig. 1(b) shows a left side view, Fig. 1(c) shows a right side view, Fig. 1(d) shows a front view, Fig. 1(e) shows a rear view, Fig. 1(f) shows a bottom side view, and Fig. 1(g) shows a perspective view with dimensions.

[0019] The main body of the ferrite core 100 has a band shape as shown in Fig. 1(a) to Fig. 1(g). The ferrite core 100 is suitably used as a noise filter or electromagnetic wave shield for a frequency band according to the type of ferrite, although the use of the ferrite core 100 is not limited to these.

[0020] The ferrite core 100 body includes a powder for ferrite cores in which ferrite and pulverized ore containing at least silicon as one of the main components are mixed in a ratio of 85wt%:15wt%-99wt%:1wt%.

[0021] Before ferrite cores became mainstream as noise filters, silicon steel sheets were used, but their use was limited due to the fact that they generate heat. Nevertheless, silicon components have noise removal and electromagnetic shielding functions, and it was discovered that by mixing a relatively small amount of silicon with ferrite, it is possible to improve the noise removal and electromagnetic shielding performance compared to when manufacturing cores using ferrite alone.

[0022] The ferrite core 100 body may be manufactured, for example, by adding ferrite core powder and a vulcanizing agent to a resin precursor (e.g., silicon), thoroughly kneading the mixture in a kneader, loading the mixture into a flat plate mold that will serve as the prototype for the ferrite core 00, vulcanizing it by applying pressure and heat in a press molding machine to create a flat plate, and then pressing the flat plate using a punching die that corresponds to the ferrite core 00, and vulcanizing the resulting plate again in a high-temperature exhaust furnace.

[0023] The ratio of the ferrite core powder and the resin precursor can be, for example, 60wt%:40wt% to 40wt%:60wt%. The ferrite core 100 body typically has a ratio of resin:ferrite:ore of, for example, 50wt%:45wt%:5wt%.

[0024] The resin functions as a binder for the powder for the ferrite core. A resin having fire resistance, oil resistance, etc. may be used depending on the environment in which the ferrite core 100 is used. The resin is not limited to these, but examples of the resin that can be used include silicon-based resin, polyimide-based resin, polypropylene-based resin, and polyurethane-based resin.

[0025] The resin does not have any particular required characteristics and is not limited in characteristics, but a general-purpose resin with a hardness of 30 to 70 (for example, 50) can be used to obtain the required flexibility. However, since chlorinated resins such as vinyl chloride resins may react with mineral components of the ore and deteriorate, it is not preferable to actively use such resins in the manufacture of the ferrite core 100.

[0026] The ferrite may be any soft ferrite that exhibits soft magnetism. Therefore, the type of magnetism (anisotropy / isotropy) of the ferrite is not important, and the crystal structure is also not important. If forced to say, the ferrite used in this embodiment is preferably a hexagonal ferrite such as strontium ferrite or barium ferrite, but spinel ferrite such as manganese / nickel zinc ferrite and garnet ferrite such as yttrium iron garnet ferrite can also be used.

[0027] The ferrite has an average primary particle size (a particle size distribution obtained by measuring with a laser diffraction particle size distribution measuring device (e.g., Microtrack, manufactured by Nikkiso Co., Ltd.), and for each divided particle size range (channel), a cumulative distribution is subtracted from the small particle size side by volume, and the particle size is determined to be 50% of the total particle size) of 10 μm or less.

[0028] As described above, the ore contains at least a silicon component as one of the main components, but the ore used in this embodiment also contains a calcium component, a magnesium component, an aluminum component, an iron component, etc. The average primary particle size of the ore was also measured by the above-mentioned measuring method and was set to 10 μm or less.

[0029] Table 1 shows the results of chemical analysis of the powder for ferrite cores according to the present embodiment by fluorescent X-ray analysis. Table 1 does not list components below 1 wt%, but examples of such components include sodium, titanium, manganese, and phosphorus.

[0030] [Table 1]

[0031] The ferrite core 100 is broadly divided into a first end portion 10, a second end portion 20, and a body portion 30, which will be described below. The ferrite core 100 is integrally molded by the manufacturing method already described.

[0032] The first end 10 has a through hole 12, and is therefore wider (e.g., about 1.5 to about 2 times) than the second end 20 and the body 30. The through hole 12 has a longitudinal length x that corresponds to the width X of the body 30 (e.g., 0.9X≦x≦1.1X, preferably 0.95X≦x≦1.05X), and a lateral length y that corresponds to, for example, twice the thickness T of the body 30 (e.g., 0.9T≦y / 2≦1.1T, preferably 0.95T≦y / 2≦1.05T).

[0033] The through hole 12 is not limited to the shape shown in Fig. 1, and for example, the four corners can be rounded. In this way, it is possible to prevent the ferrite core 100 from being torn by application of an external force to the corners. The through hole 12 can also be in a shape shown in Fig. 6 described later, and in this case, it can be in a rounded shape without corners.

[0034] Incidentally, specific dimensional examples of each part of the ferrite core 100 will be described later with reference to those shown in FIG. 6, but the meaning of "correspondence" in the explanation of dimensions in this specification is that each numerical value can be changed by approximately ±15%.

[0035] The second end 20 is a portion that is passed through the through hole 12 multiple times (for example, twice) while the ferrite core 100 body is wound around a winding target (not shown) such as an electric wiring cable. The second end 20 has a chamfered corner to make it easier to pass through the through hole 12, but the second end 20 itself may be, for example, semicircular.

[0036] The body portion 30 is a portion located between the first end portion 10 and the second end portion 20. The body portion 30 has a holding portion 40 that holds the ferrite core 100 body in a wound state around a winding target. In this embodiment, the holding portion 40 is composed of a plurality of protrusions 42 protruding from the surface of the body portion 30. Each protrusion 42 has a cross section in the short side direction that is substantially in the shape of a right-angled triangle, and adjacent protrusions 42 are arranged with a relatively small gap (for example, a gap corresponding to the thickness T of the body portion 30) therebetween.

[0037] Any one of the protrusions 42 is engaged with the edge of the through hole 12, thereby maintaining the ferrite core 100 body wound around the object to be wound. The pitch p and height h of the protrusions 42 may be determined taking into account the thickness T of the trunk portion 30.

[0038] The ferrite core 100 is wound around an object to be wound, such as an electric wiring cable, so that the main body of the ferrite core 100 has an approximate cylindrical shape. From the viewpoint of impedance of the ferrite core 100, as described above, the larger the cylindrical outer diameter is, and the smaller the cylindrical inner diameter is, the better. In this embodiment, the ferrite core 100 is in the form of a flexible band, so that it can be wound around an object to be wound, such as an electric wiring cable, with a certain degree of freedom.

[0039] Therefore, if the ferrite core 100 is wound around the object to be wound in such a manner that the gap between the ferrite core 100 and the object to be wound is minimized, the inner diameter of the cylinder can be made small, and if the ferrite core 100 is wound around the object to be wound two or more times, the outer diameter of the cylinder can be made large. Therefore, the ferrite core 100 can effectively remove noise.

[0040] (Embodiment 2) Fig. 2 is an explanatory diagram of a ferrite core 100 according to a second embodiment of the present invention, and Fig. 2(a) to Fig. 2(g) correspond to Fig. 1(a) to Fig. 1(g), respectively. What is shown in Fig. 2 differs from what is shown in Fig. 1 in that a holding portion 40 is formed not only on the front surface of the body portion 30 but also on the back surface.

[0041] With the configuration shown in FIG. 2, it is possible to wind the ferrite core 100 in such a manner that the convex portion 42 on the front surface of the first turn and the convex portion 42 on the back surface of the second turn fill in the unevenness, and the ferrite core 100 can be made high density when cylindrical.

[0042] (Embodiment 3) Fig. 3 is an explanatory diagram of a ferrite core 100 according to a third embodiment of the present invention, and Fig. 3(a) to Fig. 3(g) correspond to Fig. 1(a) to Fig. 1(g), respectively. What is shown in Fig. 3 differs from that shown in Fig. 1 in that the holding portion 40 has adjacent protrusions 42 arranged with a relatively large gap therebetween (for example, a gap corresponding to twice the thickness T of the body portion 30).

[0043] When the holding portion 40 shown in Fig. 3 is applied, the edge of the through hole 12 is received even in a large gap between adjacent protrusions 42 (i.e., the surface of the body 30 itself), which contributes to reducing the height of the protrusions 42. In this case, too, the ferrite core 100 can be made high density when cylindrical, similar to the ferrite core 100 shown in Fig. 2.

[0044] In the ferrite core 100 shown in Fig. 3, both ends of each protrusion 42 are located inside the end face of the body portion 30 (the longitudinal length of each protrusion 42 can be, for example, 80% to 90% of the distance between the end faces of the body portion 30), but both ends of each protrusion 42 may extend to the end faces of the body portion 30 as shown in Fig. 1. Conversely, both ends of each protrusion 42 of the ferrite core 100 shown in Figs. 1 and 2 may be located as shown in Fig. 3.

[0045] (Embodiment 4) Fig. 4 is an explanatory diagram of a ferrite core 100 according to a fourth embodiment of the present invention, and Fig. 4(a) to Fig. 4(g) correspond to Fig. 1(a) to Fig. 1(g), respectively. The ferrite core 100 shown in Fig. 4 is a hybrid of the technical ideas shown in Fig. 2 and Fig. 3.

[0046] That is, the ferrite core 100 shown in Fig. 4 has the holding portion 40 in the form shown in Fig. 3 formed on both the front and back surfaces of the body portion 30. Therefore, the ferrite core 100 shown in Fig. 4 has the highest density when it is cylindrical among the ferrite cores 100 described so far.

[0047] In addition, in the ferrite core 100 shown in Fig. 4, adjacent protrusions 42 are arranged with a relatively large gap between them, so when the protrusions 42 on the front side of the first turn of the ferrite core 100 and the protrusions 42 on the back side of the second turn of the ferrite core 100 are wound in such a manner that they fill in the unevenness, the protrusions and recesses interlock and are less likely to slip. This effect can also be obtained with the ferrite core 100 shown in Fig. 2, but the ferrite core 100 shown in Fig. 4 can achieve a stronger interlocking shape.

[0048] (Embodiment 5) Fig. 5 is an explanatory diagram of a ferrite core 100 according to a fifth embodiment of the present invention, and Fig. 5(a) to Fig. 5(g) correspond to Fig. 1(a) to Fig. 1(g), respectively. What is shown in Fig. 5 differs from that shown in Fig. 1 in that the cross-sectional shape in the short side direction of each protrusion 42 is substantially semicircular, and a relatively large gap is provided between each protrusion 42 in the holding portion 40.

[0049] When a highly viscous resin is used for the ferrite core 100 body, the resin may not flow sufficiently in the mold during manufacturing, and may not reach the tip of the protrusion 42. In view of this, the shape of each protrusion 42 of the ferrite core 100 shown in Fig. 5 is changed to avoid product variation.

[0050] It should be noted that a holding portion 40 in which each protrusion 42 has a substantially semicircular cross section in the short side direction as shown in FIG. 5 can also be applied to the ferrite core 100 shown in FIGS.

[0051] (Embodiment 6) Fig. 6 is an explanatory diagram of a ferrite core 100 according to a sixth embodiment of the present invention, and Fig. 6(a) to Fig. 6(g) correspond to Fig. 1(a) to Fig. 1(g), respectively. What is shown in Fig. 6 differs from what is shown in Fig. 1 in that holding parts 40 are formed on both side surfaces instead of the surface of the body part 30, and in that the shape of the through hole 12 has been modified accordingly.

[0052] 6 has a convex shape in which a tip-side cavity 12a and a base-side cavity 12b are adjacent to each other. The length x1 of the tip-side cavity 12a in the longitudinal direction corresponds to the width X1 of the body 13. The length x2 of the base-side cavity 12b in the longitudinal direction corresponds to the width X2 obtained by adding the total height 2h of the convex portions 42 on each side to the width X1 of the body 13. The length y of each of the tip-side cavity 12a and the base-side cavity 12b in the lateral direction corresponds to the thickness T of the body 13.

[0053] With such dimensions, when the second end 20 is passed through the through hole 12 multiple times while the ferrite core 100 body is being wound around a winding target, the first time, the second end 20 and the body 30 pass through the base end cavity 12b without difficulty. Also, the second time, while the second end 20 passes through the tip end cavity 12a without difficulty, the body 30 passes through while the protrusion 42 slightly expands the short side of the tip end cavity 12a, and finally the protrusion 42 is engaged with the edge of the short side of the tip end cavity 12a.

[0054] Note that the through hole 12 shown in Figure 6 shows an example in which the second end 20 is passed through twice while the ferrite core 100 body is wound around the winding target. However, if the second end 20 is designed to be passed through three times, the short-side length y of the base-end cavity 12b should correspond to twice the thickness T of the body portion 13.

[0055] In the ferrite core 100 shown in FIG. 6, the volume of the protrusions 42 can be relatively reduced, so that the body of the ferrite core 100 can be made lighter, and the material costs can be reduced accordingly.

[0056] The actual dimensions of the ferrite core 100 shown in FIG. 6 are exemplified as follows: The ferrite core 100 body has a total length of 110 mm, a total width (the width of the first end 10 which is the maximum width) of 35 mm, and a thickness T of 2 mm. The first end 10 has a total length of 25 mm, a length from that end to the tip cavity 12a of 9.8 mm, a length from the end to the point where it narrows toward the body 30 of 20 mm, a length x1 of 20 mm, a length x2 of 24 mm, y of 2.3 mm, a total width of 35 mm, and each corner of the end is 6-R5. The second end 20 has a length (the length from that end to the position where the inclination of the first protrusion 42 begins) of 8 mm, a width of 20 mm, an end width of 18 mm, and each corner of the end is 2-R3. The body 30 has a length of 85 mm, a width (length X1) of 20 mm, and a thickness T of 2 mm. The holding portion 40 has a height h of 2 mm, a length (slope length) of 4 mm, and a pitch p of 6.25 mm at the protrusion 42. It is.

[0057] In addition, the pitch p of the protrusions 42 is 6.25 mm, and is set based on the thickness T of the body 30 being 2 mm, so that if theoretically no gap occurs between the first and second turns when the ferrite core 100 is wound around it and used, the pitch p is set to approximately 2πT, or approximately 12.56 mm, as a standard, and is set to, for example, half that, or approximately 6.28 mm, to enable fine engagement so that no gap occurs.

[0058] The dimensions of the ferrite core 100 in other embodiments may be similar to those exemplified here. However, since the dimensions of the ferrite core 100 vary depending on the thickness of the object to be wound, it should be noted that the above dimensions are merely examples.

[0059] Fig. 7 is a diagram showing an example of use of the ferrite core 100 shown in Fig. 6. Fig. 7 shows a state in which the second end 20 is passed twice through the through hole 12 while the ferrite core 100 body is wound around the electric wiring cable 200 and held by the holding part 40.

[0060] The ferrite core 100 can be used to eliminate noise not only by winding it around a linear object such as the electric distribution cable 200, but also by attaching it to a breaker itself or a distribution board that has the breaker inside. In such a case, it is also effective to make the ferrite core 100 plate-shaped and attach it to a predetermined position on the distribution board or the like with tape.

[0061] Incidentally, it is preferable to wrap tape around the outer periphery of the ferrite core 100 shown in FIG. 7, as this helps prevent the ferrite core 100 wound around the electric distribution cable 200 from coming off or becoming loose.

[0062] The tape may be made of aluminum or the like, and may have a function of shielding electromagnetic waves including noise. If the tape has an electromagnetic wave shielding function, it is possible to direct noise generated from the electric wiring cable 200 toward the ferrite core 100, which has the advantage of enhancing the noise removal effect. [Brief description of the drawings]

[0063] [Figure 1] 1 is an explanatory diagram of a ferrite core 100 according to a first embodiment of the present invention. [Diagram 2] 1 is an explanatory diagram of a ferrite core 100 according to a second embodiment of the present invention. [Diagram 3] 1 is an explanatory diagram of a ferrite core 100 according to a third embodiment of the present invention. [Figure 4] 1 is an explanatory diagram of a ferrite core 100 according to a fourth embodiment of the present invention. [Diagram 5] 1 is an explanatory diagram of a ferrite core 100 according to a fifth embodiment of the present invention. [Figure 6] FIG. 11 is an explanatory diagram of a ferrite core 100 according to a sixth embodiment of the present invention. [Figure 7] 7 is a diagram showing an example of use of the ferrite core 100 shown in FIG. 6. [Explanation of symbols]

[0064] 10 First end 12 Through hole 12a Tip side cavity 12b Proximal cavity 20 Second end 30 Torso 40 Holding part 42 Convex 100 Ferrite Core 200 Electrical wiring cable

Claims

1. A ferrite core containing a powder for ferrite cores and a flexible resin serving as a binder for the powder for ferrite cores in a ratio of 40 wt %:60 wt % to 60 wt %:40 wt %, The ferrite core powder is a mixture of ferrite and a pulverized product of an ore containing at least a silicon component as one of its main components in a ratio of 85 wt%:15 wt% to 99 wt%:1 wt%, The ferrite core body is strip-shaped. a first end having a through hole; a second end portion that is passed through the through hole while the ferrite core body is being wound around a winding object; a trunk portion having a holding portion that holds the ferrite core body in a wound state around a winding target; Equipped with The second end is a ferrite member that is passed through the through hole a plurality of times.

2. 2. The ferrite core according to claim 1, wherein the ferrite and the pulverized material each have a primary particle size of 10 μm or less.

3. the holding portion has a plurality of protrusions, any one of which is adapted to engage with an edge of the through hole, 2. The ferrite core according to claim 1, wherein a pitch p of each of said projections corresponds to a thickness T of said body portion.

4. the holding portion has a plurality of protrusions, any one of which is adapted to engage with an edge of the through hole, 2. The ferrite core according to claim 1, wherein the pitch p of each of said projections is based on the thickness T of said body portion.

5. The through hole has a distal cavity and one or more proximal cavities adjacent to each other, the holding portion has a plurality of protrusions protruding from the body portion, any one of which is engaged with an edge of the through hole, The length x1 of the tip cavity in the longitudinal direction corresponds to the width X1 of the body portion, The longitudinal length x2 of the base end cavity corresponds to a width X2 obtained by adding the width X1 of the body portion to the total height 2h of the protrusions on each side, The length y of each of the distal end cavity and the proximal end cavity in the short side direction corresponds to the thickness T of the body portion. The ferrite core according to claim 1.

6. The ferrite core according to claim 1 , wherein the ferrite core body is covered with tape after being wound around the object to be wound.

7. The ferrite core according to claim 1 , wherein the object to be wound is an electric wiring cable.

8. 2. The ferrite core according to claim 1, wherein the ferrite core body is plate-shaped and is covered with tape in a state where the ferrite core body is attached to an object to which the ferrite core is attached.

9. The ferrite core according to claim 1, The powder for ferrite cores is a mixture of ferrite and pulverized ore containing at least silicon as one of its main components in a ratio of 85 wt %:15 wt % to 99 wt %:1 wt %.

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