JP2012099739A - Core segment, annular coil core and annular coil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a core segment, an annular coil core and an annular coil in which excellent heat dissipation is ensured while holding a desired magnetic performance, the number of turns of a conductor can be increased easily, and damage on the insulation coating of the conductor can be reduced when winding the conductor.SOLUTION: The core segment comprises winding parts 5a, 5b formed by binding metal magnetic powder with a nonmagnetic binder or by shaping a metal magnetic body and around which an insulation-coated conductor is wound, non-winding parts 6a, 6b formed respectively and continuously to both ends of the winding parts in the longitudinal direction and around which the conductor is not wound, and joint surfaces 7a, 7b formed at the ends of the non-winding parts to intersect the magnetic flux generated when the conductor wound around the winding parts is energized.

Description

  The present invention relates to an annular coil used for power supply circuits of various devices, and more particularly to a core segment and an annular coil core that are parts used for manufacturing an annular coil.

  A toroidal coil is required to have high inductance as a component used for boosting, smoothing, or preventing noise of a switching power source, and the core shape is annular in order to increase the inductance. Such an operation for winding a lead wire around an annular part requires a considerable amount of labor and time if it is carried out manually, which increases the manufacturing cost. In addition, since the toroidal coil annular core has a rectangular cross-sectional shape, it is difficult for the winding to come into contact with only the corner portion of the core and to bring the winding into close contact with the surface of the core. In order to solve these problems, various winding methods and winding devices have been proposed.

  For example, Patent Document 1 proposes a winding method of a toroidal coil in which a conducting wire having a large wire diameter is wound around a core. Patent Document 2 proposes a winding device for automatically performing winding. Further, Patent Document 3 proposes a toroidal coil manufacturing method in which an annular core is divided into a plurality of parts, and the divided core parts are inserted into coil conductors that are pre-shaped into a coil shape.

JP 2010-103434 A JP 2002-289455 A JP 2001-68364 A

  However, in the conventional toroidal coil, as shown in FIG. 8, when the conductor is wound manually or when the conductor is wound around the core using the method or apparatus described in Patent Documents 1 and 2, Since the conductive wire 104 is concentrated on the inner peripheral side of 103, the central space 109 of the core is narrowed by the conductive wire 104, and the conductive wire 104 cannot be wound when the number of turns exceeds a certain value. As a countermeasure, if the core inner diameter is increased, the outer diameter of the coil is increased, and the user's request for downsizing of electronic components cannot be met.

  In addition, in a two-layer or three-layer wound toroidal coil, the winding tends to generate heat and become overheated, so it is necessary to release heat from the winding. However, the conventional toroidal coil has poor heat dissipation, and particularly the heat dissipation on the inner circumference side of the coil is remarkably poor, so that there is a risk that the temperature of the winding rises and does not function normally. That is, as shown in FIG. 9, the winding 104 of the toroidal coil is in contact with only the corner portion of the rectangular cross-section core 103 and is easily wound away from the core surface 108. It is difficult for heat to escape and overheated easily.

  Moreover, in the toroidal coil of patent document 3, since the conducting wire is wound around the joint or gap between the split cores, the magnetic flux leaks from the joint or gap. This leakage magnetic flux induces and generates eddy currents in the conductors, causing current loss in the conductors, which may cause coil heat generation or increased iron loss.

  The present invention has been made in order to solve the above-described problems, and has excellent heat dissipation while maintaining a desired magnetic performance, and can easily increase the number of windings of the conductive wire, and insulate the conductive wire at the time of winding. An object of the present invention is to provide a core segment, an annular coil core, and an annular coil that can reduce damage to the coating.

  The core segment according to the present invention is formed by bonding metal magnetic powder with a non-magnetic binder, or by forming a metal magnetic body, and a winding portion around which an insulation coated conductor is wound, It is formed continuously at both ends in the longitudinal direction, and the non-winding portion where the conducting wire is not wound, and the direction that intersects the magnetic flux generated when the conducting wire wound around the winding portion is energized, And a joining surface formed at a terminal end of the non-winding portion.

  The annular coil core according to the present invention is formed by combining metallic magnetic powder with a nonmagnetic binder or molding a metallic magnetic body, and the first winding portion around which the insulation coated conductor is wound, It is generated when energized to the first non-winding portion where the conducting wire is not wound and the conducting wire wound around the first winding portion, which are respectively continuous at both ends in the longitudinal direction of one winding portion. A first core segment having a first joint surface formed at a terminal end of the first non-winding portion, which is in a direction intersecting with a magnetic flux, and a metal magnetic powder coupled with a non-magnetic binder. Formed or formed by molding a metal magnetic body, the second winding portion around which the insulation-coated conductor wire is wound, and the longitudinal ends of the second winding portion, which are continuous with each other, and the conductor wire is wound around The second non-winding portion that is not provided and the first non-winding portion facing the first joint surface. And a second joint surface formed at the end of the second non-winding portion, which is in a direction intersecting with the magnetic flux generated when the conducting wire wound around the second winding portion is energized And a second core segment.

  The annular coil according to the present invention is formed by combining an insulation-coated conductor and a metal magnetic powder with a nonmagnetic binder, or by molding a metal magnetic body, and the first coil around which the insulation-coated conductor is wound. A wire portion, a first non-winding portion that is continuous to each longitudinal end of the first winding portion, and the conductive wire is not wound thereon, and a conductive wire wound around the first winding portion. A first core segment having a first joint surface formed at a terminal end of the first non-winding portion, which is in a direction intersecting with a magnetic flux generated when energized, and a non-metallic magnetic powder. It is formed by bonding with a magnetic binder or by molding a metal magnetic body, and is continuous to both ends in the longitudinal direction of the second winding portion around which the insulation-coated conductive wire is wound. A second non-winding portion around which the conducting wire is not wound, and the first Formed at the end of the second non-winding part, which is arranged opposite to the joint surface and is in a direction crossing the magnetic flux generated when the conducting wire wound around the second winding part is energized And a second core segment having a second joining surface.

  Since the core segment of the present invention can be wound around the core winding portion by utilizing the free space around the core winding portion without passing the conducting wire through a narrow gap, even if the lead wire has a large wire diameter, A conducting wire can be wound in close contact with the surface (FIG. 7). For this reason, heat generated in the winding is easily transmitted to the core, heat can be released from the non-winding portion through the core to the outside, and the heat dissipation performance of the entire coil is greatly improved.

  According to the present invention, the concentration of windings in the conventional toroidal coil central space (FIG. 8) is eliminated, and the number of turns of the conductor wound around the core can be increased (FIG. 2), thereby increasing the inductance. It becomes easy. Further, if the number of turns is the same, the product of the present invention can further reduce the thickness of the coil as compared with the conventional product.

  In addition, according to the present invention, since the conducting wire can be wound around the core winding portion using the free space around the core winding portion without passing through a narrow gap, an excessive repeated bending force is applied to the conducting wire. There is an advantage that an inexpensive conductive wire covered with a general-purpose general insulating coating can be used instead of an expensive conductive wire coated with an insulating coating that is not easily peeled off.

The perspective view which shows the coil which concerns on embodiment of this invention. The top view which shows the coil which concerns on embodiment of this invention. (A)-(d) is a figure which shows the coil core of other embodiment, respectively. (A) is a figure which shows the core segment of embodiment, (b) is sectional drawing which shows the core segment of embodiment, (c) is sectional drawing which shows the core segment of other embodiment, (d) is other implementation. Sectional drawing which shows the core segment of form. (A) is a figure which shows the coil of embodiment, (b) is a figure which shows the coil of other embodiment, (c) is a figure which shows the coil of a comparative example. The characteristic diagram which shows the correlation with a coil electric current, an inductance, and the gap G. FIG. Sectional drawing which shows the contact state of the coil core and winding | winding of this invention. The figure which shows the conventional toroidal coil. Sectional drawing which shows the contact state of the conventional toroidal core and a coil | winding.

  Hereinafter, various preferred embodiments of the present invention will be described.

  (1) The core segment of the present invention is formed by combining metallic magnetic powder with a nonmagnetic binder or molding a metallic magnetic body, and a winding portion around which an insulation-coated conductive wire is wound, and the winding A non-winding portion that is continuously formed at both ends in the longitudinal direction of the portion, and on which the conducting wire is not wound, and a direction that intersects the magnetic flux generated when the conducting wire wound on the winding portion is energized And a joining surface formed at the end of the non-winding portion.

  According to the present invention, since the conductor can be wound around the winding portion using the free space around the core winding portion without passing through a narrow gap, even a thick conductor is in close contact with the surface of the core The conductor can be wound with (FIG. 7). For this reason, heat is easily transmitted from the winding to the core, heat can be efficiently released from the winding through the core to the outside, and the heat dissipation performance of the entire coil is improved.

  Further, in the present invention, since the conducting wire is not wound around the non-winding portion including the joint surface, the magnetic flux leaking from the joint or gap does not reach the conducting wire, and the magnetic flux generates a loss without inducing eddy current. do not do.

  As metal magnetic powder, pure iron powder, Fe-Si alloy powder (containing 3-8 mass% Si), Fe-Si-Al alloy powder (Sendust), Fe-Ni alloy powder, Mn-Zn ferrite powder, Ni -Zn-based ferrite powder can be used. Alternatively, these amorphous powders or these nanocrystal powders may be used. Moreover, a silicon steel plate or a silicon steel amorphous ribbon can be used as the metal magnetic body.

  (2) In (1), it is preferable that the non-winding part is inflected with respect to the winding part (FIGS. 1, 2, 3A, 4B, 4A), FIG. 5 (a) (b)). When the conductors are wound around the two core segments whose non-winding portions are inflected in this way, facing each other and joining each other with the joint surfaces, the shape of the core is arranged in an annular shape, and the conventional toroidal core An annular closed magnetic circuit can be created in the same manner as in FIG. Since no conducting wire is wound around the joining surface, the leakage magnetic flux generated from the joining surface does not reach the conducting wire, and the magnetic flux does not induce an eddy current and no loss occurs.

  (3) In (1), it is preferable to make the winding portion straight (FIGS. 1, 2, 3A, 3C, 5D). Thus, the degree of adhesion of the conducting wire to the surface of the core is increased by winding the conducting wire around the two core segments each having the winding portion straightened. For this reason, heat generated in the winding is easily transmitted to the core, heat can be released from the non-winding portion through the core to the outside, and the heat dissipation performance of the entire coil is greatly improved.

  (4) In (1), the winding portion may be curved (FIG. 3 (b), FIG. 5 (b)). When the winding part is curved, the degree of adhesion of the conducting wire to the core surface is inferior to that of the straight winding part, and the heat dissipation performance of the coil is also inferior. However, in the present invention, since the conductive wire can be wound around the core winding portion using the free space around the core winding portion, the number of windings of the conductive wire and the coil thickness are increased compared to the conventional product (toroidal coil). Can be made thinner.

  (5) In (1), it is preferable to make the length L4 of the winding part longer than the length L3 of the non-winding part (FIG. 2). As the length L4 of the winding portion is increased, the number of windings of the conducting wire is increased, so that the inductance L is increased.

  (6) In (1), it is desirable to further have an electrical insulating coating that covers and electrically insulates the winding portion (FIG. 2). In the present invention, since the peripheral surface of the winding portion is covered with the electrical insulation film, even if the insulation film of the conductive wire is damaged by any chance when the conductive wire is wound around the winding portion, the core magnetic body and the insulation coating are formed. Rare shorts due to contact with damaged conductors can be suppressed. As an electrical insulator that forms an electrical insulation film covering the winding part, either a paint containing a resin such as epoxy or urethane, a tape containing a resin such as epoxy or polyester, silicone, polyvinyl alcohol, or water glass is used. Any of a coated film, a heat shrinkable tube such as polyolefin or polyvinyl chloride (PVC), or a case containing a resin such as PET can be used. However, the joint surface constituting the joint or gap must not be covered with an insulating film. Since there is no insulator on the joint surface, the magnetic bodies come into contact with each other on the joint surface, so that the gap width is suppressed and a decrease in inductance can be minimized. In other words, when the bonding surface is covered with the electric insulating film, the electric insulating film sandwiched between the bonding surfaces substantially becomes a gap, and the inductance is reduced. In the present invention, since there is no electrical insulating coating on the joint surface, a gap is intentionally formed in the annular coil. That is, when it is desired to control the magnetic characteristics of the coil, the gap length can be set finely, and variations in characteristics between coil lots can be suppressed. Note that heat dissipation is not impaired unless the non-winding portion is covered with an electrically insulating coating. However, the non-winding portion may be covered with an electrical insulating coating.

(7) The annular coil core of the present invention is formed by combining metal magnetic powder with a nonmagnetic binder or molding a metal magnetic body, and a first winding portion around which an insulation coated conductor is wound, A first non-winding portion that is formed continuously at both ends in the longitudinal direction of the first winding portion and the conductive wire is not wound thereon, and a conductive wire wound around the first winding portion is energized. A first core segment having a first joint surface formed at a terminal end of the first non-winding portion, the first core segment being in a direction intersecting with the magnetic flux generated when
A metal magnetic powder is formed by bonding with a non-magnetic binder, or a metal magnetic material is formed, and a second winding portion around which an insulation coated conductor is wound, and a longitudinal direction of the second winding portion A second non-winding portion that is formed continuously at both ends, the conductive wire is not wound thereon, and is disposed to face the first joint surface, and is wound around the second winding portion. A second core segment having a second joint surface formed at a terminal end of the second non-winding portion, which has a direction intersecting with the magnetic flux generated when the conducting wire is energized.

(8) The annular coil of the present invention is formed by combining an insulation-coated conductor and a metal magnetic powder with a nonmagnetic binder or molding a metal magnetic body, and the first coil around which the insulation-coated conductor is wound. Winding portions, a first non-winding portion that is continuously formed at both ends in the longitudinal direction of the first winding portion, and the conductive wire is not wound thereon, and is wound around the first winding portion. A first core segment having a first joint surface formed at a terminal end of the first non-winding portion, the first core surface being in a direction crossing a magnetic flux generated when the attached conductive wire is energized;
A metal magnetic powder is formed by bonding with a non-magnetic binder, or a metal magnetic material is formed, and a second winding portion around which the insulation-coated conductive wire is wound, and a length of the second winding portion A second non-winding portion that is formed continuously at both ends in the direction and on which the conductive wire is not wound, and is disposed to face the first joint surface, and is wound around the second winding portion. A second core segment having a second joint surface formed at the end of the second non-winding portion, the second core segment being in a direction intersecting with the magnetic flux generated when the conducting wire is energized. .

  According to the present invention, similar to the invention of (1) above, since the conducting wire can be wound around the winding portion using the free space around the core winding portion without passing through a narrow gap, Even if it exists, a conducting wire can be wound in the state closely_contact | adhered to the surface of the core (FIG. 7). For this reason, heat is easily transferred from the winding to the core, heat can be efficiently released from the non-winding portion through the core to the outside, and the heat dissipation performance of the entire coil is improved.

  (9) In (8), it is preferable that the first bonding surface and the second bonding surface are bonded (FIG. 2). When the first and second joint surfaces are bonded, they are magnetically similar to a conventional toroidal coil, and in terms of magnetic characteristics such as inductance, are comparable to conventional toroidal coils (characteristic line in FIG. 6). A and B) are superior to conventional toroidal coils in terms of heat dissipation.

  (10) In (8), a gap G may be provided between the first joint surface and the second joint surface (FIGS. 1 and 6). When a direct current is applied to the coil and exceeds a certain current value, the magnetic permeability μ decreases due to magnetic saturation (characteristic lines A and B in FIG. 6). When the gap G is provided, the magnetic resistance increases, and a large current is required until magnetic saturation occurs. Therefore, even if the current value increases, the magnetic permeability μ is stabilized within a substantially constant range (see FIG. 6). Characteristic lines C, D, E). Therefore, it becomes suitable for a noise prevention filter of a switching power supply circuit through which a large current flows.

  (11) In (8), it is preferable that the relationship between the length L3 of the non-winding portion, the diameters d1 and d2 of the conductive wire, and the number of layers m1 and m2 of the conductive wire satisfy the following formula (1).

L3> d1 · m1 + d2 · m2 (1)
However, L3: Length of said 1st and 2nd non-winding part d1: Diameter of conducting wire wound around said 1st winding part d2: Conducting wire wound around said 2nd winding part Diameter m1: number of winding layers of the conductive wire around the first winding portion m2: number of winding layers of the conductive wire around the second winding portion Winding of the conductive wire around the first and second winding portions As the number of applied layers m1 and m2 increases, the winding thickness (d1 · m1 + d2 · m2) in the right term of the equation (1) increases and the central space 9 decreases. When the central space 9 becomes zero, the back and back of the windings wound around the first and second winding portions come into contact with each other and the heat dissipation performance is hindered, leading to an overheating state.

  (12) In (8), it is preferable that the non-winding part bends with respect to the winding part (FIGS. 1, 2, 3A, 4B, 4A), FIG. 5 (a) (b)). When the non-winding portion is bent in this manner, the shape of the core is arranged in an annular shape, and an annular closed magnetic circuit can be created as in the conventional toroidal core. Since no conducting wire is wound around the joining surface, the leakage magnetic flux generated from the joining surface does not reach the conducting wire, and the magnetic flux does not induce an eddy current and no loss occurs.

  (13) In (8), it is preferable to make the winding portion straight (FIGS. 1, 2, 3A, 3C, 5D). Thus, the degree of adhesion of the conducting wire to the surface of the core is increased by winding the conducting wire around the two core segments each having the winding portion straightened. For this reason, heat generated in the winding is easily transmitted to the core, heat can be released from the non-winding portion through the core to the outside, and the heat dissipation performance of the entire coil is greatly improved.

  (14) In (8), the winding portion may be curved (FIGS. 3B and 5B). When the winding part is curved, the degree of adhesion of the conducting wire to the core surface is inferior to that of the straight winding part, and the heat dissipation performance of the coil is also inferior. However, in the present invention, since the conductive wire can be wound around the core winding portion using the free space around the core winding portion, the number of windings of the conductive wire and the coil thickness are increased compared to the conventional product (toroidal coil). Can be made thinner.

  (15) In (8), it is preferable that the length L4 of the winding portion is longer than the length L3 of the non-winding portion (FIG. 2).

  As the length L4 of the winding portion is increased, the number of windings of the conducting wire is increased, so that the inductance L is increased. There is a pedestal support method as a method of incorporating a coil in a power supply circuit. In the pedestal support method, one end of the coil is held on the pedestal, and the pedestal is mounted on a circuit board (board) so that the coil is in a vertically placed posture. However, in recent switching power supply circuits, in order to be able to cope with a large current, instead of the pedestal support system, a design in which a coil is placed on a circuit board is increasing. This is because if the coil is placed horizontally, the winding portion can be made as long as possible and the inductance L can be increased as much as desired.

  By the way, when the coil is placed horizontally, it is difficult for heat to escape from the coil, and the coil temperature tends to rise. In particular, the conventional toroidal coil is inferior in heat dissipation as shown in FIG. 8 and FIG. 9, so that the coil becomes overheated and easily breaks down. However, since the coil of the present invention has improved heat dissipation as shown in FIGS. 2 and 7, even if the coil is placed horizontally, the coil is not overheated and does not fail.

  (16) In (8), it is desirable to further have an insulating film that covers and electrically insulates the winding portion (FIG. 2). In the present invention, since the peripheral surface of the winding part is covered with the insulating film, even if the insulating film of the conductive wire is damaged by any chance when the conductive wire is wound around the winding part, the core magnetic body and the insulating film are damaged. Rare short-circuiting due to contact with the conducting wire can be suppressed.

  Hereinafter, preferred embodiments for carrying out the present invention will be described with reference to the accompanying drawings.

  First, the annular coil according to the most preferred embodiment will be described with reference to FIGS.

  The annular coil 2 of this embodiment is formed by combining a pair of coil assemblies 2a and 2b that are substantially axisymmetric with respect to the Z axis in the drawing. The coil assembly 2a on one side is composed of a core segment 3a formed in a substantially C shape within an XZ plane field of view, and an insulation-coated conductor wire spirally wound around the winding portion 5a of the core segment 3a 4a. The coil assembly 2b on the other side includes a core segment 3b formed in an inverted C shape within the XZ plane field of view, and an insulation coated conductor 4b wound around the winding portion 5b of the core segment 3b. Yes. Both core segments 3a and 3b are formed by bonding soft magnetic powder such as Fe-9% Si-5% Al alloy powder (Sendust) with a nonmagnetic binder and molding.

  The insulation-coated conductive wires 4a and 4b are pure Cu wires covered with an insulating film. Specifically, the insulating film of the conductive wire is made of polyurethane, polyester, or the like. In this embodiment, since the conducting wires 4a and 4b can be wound around the winding portion 5a using the free space around the core winding portion 5a without passing the conducting wires 4a and 4b through a narrow gap, A thin film can be used, and is cheaper than a conventional non-peelable coating wire wound around a toroidal coil.

  In the present embodiment, the core segment 3a on one side and the core segment 3b on the other side have substantially the same configuration. Therefore, only the core segment 3a on one side will be described below as a representative of both.

  The core segment 3a is integrally formed with a winding portion 5a extending in the Z-axis direction and continuously at both ends of the winding portion 5a, and is substantially orthogonal to the longitudinal axis (Z-axis) of the winding portion 5a. A non-winding portion 6a that bends in the (X-axis direction) and a joint surface 7a that forms an end of the non-winding portion 6a. The length of the non-winding portion 6a is shorter than the length of the winding portion 5a. For example, it is desirable that the ratio of the length of the winding portion 5a and the length of the non-winding portion 6a be in the range of 2: 1 to 10: 1. If the length ratio between the two is less than 2: 1, the magnetic path length L7 of the annular coil (the length of the core center line in FIG. 2) becomes longer, and the inductance L decreases. Furthermore, since the ratio occupied by the non-winding portions 6a and 6b is increased, it is against the request for downsizing the annular coil. As the proportion of the length of the winding portion 5a is increased, the length of the winding portion of the core segment is increased, and the inductance L can be increased by increasing the number of windings. When it exceeds 10: 1, it becomes difficult to balance the inductance L and the core loss.

  Further, the peripheral surface of the winding portion 5 a of the core segment is covered with the electrical insulating coating 11. By covering the winding portion 5a and the non-winding portion 6a with the electrical insulating coating 11, even if the insulating coating of the conducting wire 4a is damaged when the conducting wire 4a is wound around the winding portion 5a, it is insulated from the core magnetic body. Rare short-circuiting due to contact with the conductive wire 4a having a damaged coating is suppressed. As an electrical insulator for forming the electrical insulation film 11, a coating film containing a resin such as epoxy or urethane, a tape containing a resin such as epoxy or polyester, a coating film coated with any of silicone, polyvinyl alcohol, and water glass, Either a heat-shrinkable tube such as polyolefin or polyvinyl chloride (PVC) or a case containing a resin such as PET can be used. However, the joint surfaces 7a and 7b constituting the seam or gap must not be covered with an electrical insulating film. Since there is no insulator on the joint surface, the magnetic bodies come into contact with each other on the joint surface, so that the gap width is suppressed and a decrease in inductance can be minimized. In other words, when the bonding surface is covered with the electric insulating film, the electric insulating film sandwiched between the bonding surfaces substantially becomes a gap, and the inductance is reduced. In the present invention, since there is no electrical insulating coating on the joint surface, a gap is intentionally formed in the annular coil. That is, when it is desired to control the magnetic characteristics of the coil, the gap length can be set finely, and variations in characteristics between coil lots can be suppressed.

  In the present embodiment, only the winding portions 5a and 5b are covered with the electric insulating film 11, and the core magnetic body is exposed in the non-winding portions 6a and 6b. However, the present invention is limited to this. It is also possible to adopt a mode in which both the winding portion 5a and the non-winding portion 6a are covered with the electrical insulating coating 11 instead of the one.

  In the annular coil 2 of this embodiment, as shown in FIGS. 1 and 2, the annular coil cores 3a and 3b are rectangular or substantially rectangular. However, in the present invention, the shape of the annular coil core is not limited to this, and the shapes of the annular coil cores 3a and 3b may be oval, for example, as in the annular coil 3A shown in FIG. Further, like the annular coil 3B shown in FIG. 3B, the shapes of the annular coil cores 3a and 3b may be elliptical.

  Further, like the annular coil 3C shown in FIG. 3C, the shape of one core segment 3a may be different from the shape of the other core segment 3b. In other words, the annular coil core can be formed by combining the left and right asymmetric core segments 3a and 3b.

  Furthermore, as in the annular coil 3D shown in FIG. 3 (d), the core segments 3a and 3b are bilaterally symmetric (axisymmetric), but the joining surfaces 71a and 72a of one core segment 3a are asymmetric and the other The joint surfaces 71b and 72b of the core segment 3b may also be asymmetric.

  In the core segment 3a of the present embodiment, as shown in FIG. 4B, the shape of the joint surface 7a is a rectangular shape close to a square. However, in the present invention, the shape of the joint surface is not limited to this. For example, as shown in FIG. 4 (c), it may be a rectangle with four corners with rounded corners. An elliptical shape may be used as shown in 4 (d).

  In the annular coil 2 of this embodiment, as shown in FIG. 1 and FIG. 2, conducting wires 4a and 4b are wound around both winding portions 5a and 5b in rectangular annular coil cores 3a and 3b. However, in the present invention, the winding is not limited to this. For example, in the annular coil 2A shown in FIG. 5A, the conductive wire 4a is wound only on the winding portion 5a of the core segment 3a on one side, and the other The core segment 3b on the side may not be wound.

  Further, in the annular coil 2B shown in FIG. 5B, the conducting wires 4a and 4b are wound around the winding portions 5a and 5b of the elliptical annular coil core shown in FIG. 3B.

  An annular coil 2C shown in FIG. 5C is a comparative example not included in the present invention, and the conductive wires 4a and 4b are wound around a portion including the joint portion 7 of the core segments 3a and 3b. Similar to the toroidal coil of Patent Document 3 described above, such an annular coil 2C leaks magnetic flux at the joint 7, and eddy current is induced in the conductor by the leaked magnetic flux, and heat generation from the coil and iron loss are caused. An increase is caused.

  In the annular coil 2 shown in FIG. 1, a gap G is provided between the first joint surface 7a and the second joint surface 7b. When such a gap G is provided, the dependence of the magnetic permeability μ on the current density (magnetizing force H) is reduced, and the magnetic permeability μ is stable within a substantially constant range regardless of changes in the current density (magnetizing force H). To come.

  In FIG. 6, the horizontal axis represents current NI (A / m) and the vertical axis represents magnetic permeability μ (H / m), and the magnetic characteristics were examined by comparing various sample samples with the comparative sample. It is a characteristic diagram which shows a result. In the figure, characteristic line A is a conventional toroidal coil, characteristic line B is an annular coil without a gap (G = 0) to which the joining surface of the present invention is bonded, characteristic line C is an annular coil having a gap of 1 mm according to the present invention, and characteristics. Line D shows the result of the annular coil having a gap of 2 mm according to the present invention, and characteristic line E shows the result of the annular coil having a gap of 3 mm according to the present invention.

  As is clear from the characteristic line B in the figure, in the example sample B with no gap (G = 0), the magnetic permeability μ of the annular coil decreases rapidly with increasing current I (the slope is large). It can be seen that the example sample B without the gap is similar in magnetic characteristic to the comparative example sample A of the conventional toroidal coil.

  On the other hand, in the characteristic line C (small gap), characteristic line D (middle of the gap), and characteristic line E (large gap) in the same figure, the magnetic permeability μ gradually decreases as the magnetizing force H increases (inclination). Is small) or hardly changed (no tilt).

  Next, examples will be described.

(First embodiment)
(Manufacture of coils)
The outline | summary of each manufacturing method of the annular coil of an Example and the toroidal coil of a comparative example is demonstrated.

(Examples 1 and 2)
In Examples 1 and 2, a so-called sendust powder having a composition of Fe-9.5 mass% Si-5.5 mass% Al was used as the metal magnetic powder, and was bonded and molded with a non-magnetic binder (silicone resin 3 wt%). 2 is composed of a wire portion and a non-winding portion formed continuously at both ends in the longitudinal direction of the winding portion, and further, an epoxy resin is applied as an electrical insulator coating to the peripheral surfaces of the winding portions 5a and 5b. The core segments as shown in 3a and 3b were prepared. Each of the core segments 3a and 3b is a conductor of 1.0 mmφ around the winding portion, and the winding portions 5a and 5b are combined to be wound 30 times in the first embodiment and 80 times in the second embodiment. An annular coil was produced by connecting the joint surfaces of 3a and 3b with an adhesive.

  Each part size of the annular coil core which combined the core segment used in Example 1 is shown.

1) Length L1 of the short side of the coil core; 50 mm
2) Long side length L2 of coil core; 30 mm
3) Length of non-winding part (interval of inner peripheral surface of winding part) L3; 34 mm
4) Length of winding part (inner peripheral surface interval of non-winding part) L4; 14 mm
5) Long width L5 of the core segment; 8 mm
6) Short side width L6 of the core segment: 8 mm
7) Magnetic path length L7; 128mm
8) Gap G: 0.1 mm
However, the length L3 of the non-winding portion refers to the mutual interval between the inner peripheral surfaces 8a of the opposing winding portions, and this includes the gap G.

  The length L4 of the winding portion refers to the mutual interval between the inner peripheral surfaces of the non-winding portions.

(Comparative Examples 1 and 2)
In Comparative Examples 1 and 2, a metal magnetic powder-nonmagnetic binder mixed powder similar to that of the example was molded, and an epoxy resin was applied to the surface as an electrical insulator coating, thereby providing a toroidal core (outer diameter 45 mm, inner diameter 37 mm, high 10 mm). The toroidal core was a 1.0 mmφ wire, and Comparative Example 1 was wound 30 times, and Comparative Example 2 was wound 80 times by hand to produce a toroidal coil.

(Coil pressure resistance test)
Table 1 shows the number of rejected products produced by preparing 20 coils for each of Examples 1 and 2 and Comparative Examples 1 and 2 and using an insulation withstand voltage tester. The conditions of the withstand voltage test were that a leakage current of less than 1 mA when a voltage of 2 kV was applied for 1 minute passed, and a failure of 1 mA or more was rejected. In addition, a conducting wire is a pure Cu wire covered with an insulating film, and the thick film (1 type: 0.025 mm) and the thin film (2 types: 0.017 mm) were evaluated.

  No difference was found in the pressure resistance test for one type of conductive wire with a thick coating, but when the coating was thin with two types, the coil wound by hand on the toroidal core of the comparative example, The number of unacceptable products in the pressure test increased due to coating damage in the winding process. In the embodiment, since the conductive wire can be wound around the winding portion using the free space around the core winding portion without passing through a narrow gap, it is possible to use a thin insulating coating.

(Second Embodiment)
As Example 3, the core segments 3a and 3b produced in the same manner as in Example 1 were wound around the winding part with a 1.4 mmφ conductor wire, and the winding parts 5a and 5b were wound 60 times, and the core segment 3a, An annular coil was produced by connecting each joint surface of 3b with an adhesive. The size of each part of the annular coil core is the same as in the first embodiment. Further, as Comparative Example 3, a toroidal coil was manufactured by winding a toroidal core manufactured in the same manner as in Comparative Example 1 60 times with a 1.4 mmφ conductor. Further, as Comparative Example 4, as shown in FIG. 5C, an annular coil was also produced which was produced by winding a conducting wire around the part including the joint 7 of the core segments 3 a and 3 b under the same conditions as in Example 3.

(Coil heat dissipation performance test)
Each of the coils of Example 3 and Comparative Examples 3 and 4 was energized at 200 V and 15 A, and the temperature after 1 minute of energization and after 5 minutes of energization was measured using an infrared thermometer. Measurement point 1 is on the conductor of the winding part, measurement point 2 is on the non-winding part, measurement point 3 is on the conductor of the winding part (near the joint 7), measurement point 4 is on the non-winding part, and measurement point 5 6 is an arbitrary side surface of the toroidal coil.

  In Example 3 and Comparative Example 3, the temperature rise in the coil winding portion was particularly high with energization, but at the measurement point 3 of Comparative Example 3, because the conducting wire is wound around the portion including the joint portion 7, Due to heat generation due to the generation of eddy currents in the conducting wire due to magnetic flux leakage at the joint, the temperature was higher than that at the measurement point 1 of Example 3.

  Although conduction to the core of the heat generated from the winding proceeds by energizing for 5 minutes, in Example 3 and Comparative Example 3, since there is a non-winding portion in the annular coil, the heat dissipation is excellent, The temperature decreased particularly at the non-winding part (measurement points 2 and 4). However, in the toroidal coil of Comparative Example 4, since the winding 104 is easily wound away from the core surface 108 as shown in FIG. 9, heat does not easily escape from the winding 104 toward the core 103, resulting in an overheated state. Therefore, the temperature rose further as the energization time increased.

  The annular coil of the present invention is used for an inductor applied to a power supply circuit of various devices and a choke coil as a noise prevention filter for a switching power supply.

2, 2A, 2B, 2C ... annular coil, 2a, 2b ... coil assembly,
3, 3A, 3B, 3C, 3D ... annular coil core, 3a, 3b ... core segment,
4, 4 a, 4 b ..insulated coated conductor (winding),
5a, 5b ... Winding part (long side part),
6a, 6b ... non-winding part (short side part),
7 ... Junction part, 7a, 7b ... Joint surface,
8a, 8b ... inner peripheral surface, 9 ... central space, 11 ... electrical insulation coating,
103 ... core, 104 ... conductor, 108 ... core surface, 109 ... central space,
G: Gap, L7: Magnetic path length.

Claims (16)

A metal magnetic powder is combined with a non-magnetic binder and molded, or a metal magnetic material is molded, and a winding portion around which an insulation coated conductor is wound,
A non-winding portion that is continuously formed on both ends in the longitudinal direction of the winding portion, and on which the conductive wire is not wound,
A joining surface formed at the end of the non-winding portion, which is in a direction intersecting with the magnetic flux generated when the conducting wire wound around the winding portion is energized;
A core segment characterized by comprising:   The core segment according to claim 1, wherein the non-winding portion is bent with respect to the winding portion.   The core segment according to claim 1, wherein the winding portion is straight.   The core segment according to claim 1, wherein the winding portion is curved.   The core segment according to claim 1, wherein a length L4 of the winding portion is longer than a length L3 of the non-winding portion.   The core segment according to claim 1, further comprising an electrical insulating coating that covers and electrically insulates the winding portion. A metal magnetic powder is formed by bonding with a non-magnetic binder, or a metal magnetic material is formed, and a first winding portion around which an insulation coated conductor is wound, and a longitudinal direction of the first winding portion A first non-winding portion that is formed continuously at both ends and does not wind the conductive wire, and intersects the magnetic flux generated when the conductive wire wound around the first winding portion is energized. A first core segment having a first joint surface formed at a terminal end of the first non-winding portion that is oriented;
A metal magnetic powder is formed by bonding with a non-magnetic binder, or a metal magnetic material is formed, and a second winding portion around which an insulation coated conductor is wound, and a longitudinal direction of the second winding portion A second non-winding portion that is formed continuously at both ends, the conductive wire is not wound thereon, and is disposed to face the first joint surface, and is wound around the second winding portion. A second core segment having a second joint surface formed at the end of the second non-winding portion, the second core surface being in a direction intersecting with the magnetic flux generated when the conducting wire is energized;
An annular coil core comprising: Insulated conductors;
A metal magnetic powder is formed by bonding with a non-magnetic binder, or a metal magnetic material is formed, and a first winding portion around which the insulation-coated conductive wire is wound, and a length of the first winding portion The first non-winding portion that is formed continuously at both ends in the direction and does not wind the conductive wire, and intersects the magnetic flux generated when the conductive wire wound around the first winding portion is energized. A first core segment having a first joint surface formed at a terminal end of the first non-winding portion,
A metal magnetic powder is formed by bonding with a non-magnetic binder, or a metal magnetic material is formed, and a second winding portion around which the insulation-coated conductive wire is wound, and a length of the second winding portion A second non-winding portion that is formed continuously at both ends in the direction and on which the conductive wire is not wound, and is disposed to face the first joint surface, and is wound around the second winding portion. A second core segment having a second joint surface formed at a terminal end of the second non-winding portion, the second core surface being in a direction intersecting with a magnetic flux generated when the conductive wire is energized.
An annular coil comprising:   The annular coil according to claim 8, wherein the first joint surface and the second joint surface are bonded to each other.   The annular coil according to claim 8, wherein a gap is provided between the first joint surface and the second joint surface. The annular coil according to claim 8, wherein the relationship between the length L3 of the non-winding portion, the diameters d1 and d2 of the conducting wire, and the winding numbers m1 and m2 satisfies the following expression.
L3> d1 · m1 + d2 · m2
However, L3: Length of said 1st and 2nd non-winding part d1: Diameter of conducting wire wound around said 1st winding part d2: Conducting wire wound around said 2nd winding part Diameter m1: number of winding layers of the conductive wire around the first winding portion m2: number of winding layers of the conductive wire around the second winding portion   The annular coil according to claim 8, wherein the non-winding portion is bent with respect to the winding portion.   The annular coil according to claim 8, wherein the winding portion is straight.   The annular coil according to claim 8, wherein the winding portion is curved.   The annular coil according to claim 8, wherein the length of the longitudinal axis of the winding portion is longer than the length of the longitudinal axis of the non-winding portion.   The annular coil according to claim 8, further comprising an electrical insulating coating that covers and electrically insulates the winding portion.

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