JP4131515B2 - Coil device - Google Patents

Description

  The present invention relates to a coil device.

Various types of coil devices have been proposed and put into practical use. As one of them, a coil device applicable as a vehicle-mounted antenna or a transponder of an automobile has been proposed (see Patent Document 1). A coil device of a surface mount type is used as a coil device applied for such a use, and there is a demand for downsizing / thinning, impact resistance, vibration resistance, heat resistance, and the like. .
Japanese Patent Laid-Open No. 2003-318030

  By the way, at present, in the surface mount type coil device, the insulating exterior body covering the core and the coil has a quadrangular cross-sectional shape perpendicular to the coil winding axis direction. Moreover, also in the core accommodated in the inside, from the viewpoint of the characteristic as a coil, the cross-sectional shape is often configured in a quadrangular shape in accordance with the insulating exterior body.

  However, when the core has a quadrangular cross-sectional shape, a crack may be found in the insulating outer package during the inspection process. This is because the coil winding expands due to heat when molding the insulating outer casing, and stress concentration due to expansion occurs particularly in the portion of the insulating outer casing covering the square corners of the core. It is thought that cracks occur in the surface.

  On the other hand, it is conceivable to make the cross-sectional shape of the core circular so that stress concentration is less likely to occur. However, when a circular cross section inscribed in the original square cross section is adopted, the cross sectional area of the core cannot be obtained, which is not preferable in terms of characteristics. On the other hand, if the cross-sectional shape of the core is selected to be larger than the circular shape inscribed as described above, the cross-sectional shape of the insulating outer package is a quadrilateral shape. Or the whole coil apparatus enlarges giving priority to securing thickness.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a coil device capable of preventing the occurrence of cracks in an insulating exterior body while satisfying the demand for downsizing and thinning. And

  In order to achieve the above-described object, the present invention provides a coil device including a core, a coil provided around the core, and an insulating exterior body that covers the core and the coil. A winding core portion around which the winding of the coil is wound and a pair of flange portions formed at both ends of the winding core portion, and a cross section perpendicular to the coil winding axis direction of the winding core portion is opposed in a square shape. It has a shape with a bulging portion on a pair of surfaces.

  Suitably, the bulging part of the said core part is comprised by the curve in the cross section orthogonal to a coil winding axis direction.

  Further, at least one winding escape portion is formed in the winding core portion, and the winding escape portion is in contact with the bulging portion and the bulging portion as seen in a cross section of the winding core portion. It is preferable that it is formed so as to be recessed inward from an arc-shaped line connecting the square corners on both sides.

  It is preferable that the winding core portion has flat portions on both sides of the bulging portion, and the flat portion is formed between another pair of opposing surfaces in the rectangular shape and the bulging portion. It is.

  Preferably, between the outer peripheral surface of the core portion and the surface of the flange portion on the core portion side is R-processed or tapered, and / or the surface of the flange portion on the core portion side. R processing is performed between the outer circumferential surface on the radially outer side.

  According to the coil device of the present invention, when the coil winding is wound around the core portion, the winding is wound in a shape closer to a circle as seen in the cross section than when the bulging portion is not provided. . Therefore, even if the coil expands due to heat when molding the insulating outer package, stress concentration is mitigated in the portion of the insulating outer casing that covers the windings at the corners of the core portion. It is possible to prevent cracks from occurring. In addition, since the bulging portion is formed on a pair of opposing surfaces in the quadrangular shape in the cross-sectional shape of the core portion, the coil device can be reduced in size while preventing the occurrence of cracks in the insulating exterior body as described above. To meet the demands of the

  Further, when the bulging portion is formed of a curved line in the cross-sectional shape, it is possible to avoid a new stress concentration by providing the bulging portion.

  In addition, when the winding escape portion is formed in the winding core portion, when the coil expands, a part of the winding can enter the winding escape portion. The rate at which the wire exerts an expansion force on the outer insulating outer casing is reduced, and cracks can be effectively prevented even in the vicinity of the corner of the insulating outer casing where cracks are a problem.

  In addition, when flat portions are formed on both sides of the bulging portion, it is possible to prevent a large compression reaction force from acting on the end portion of the mold when the core portion is manufactured by compression molding of powder. it can. Therefore, a sufficient compressive force can be applied, and damage to the mold in a short period can be prevented.

  In addition, when a larger R machining is applied to the connection portion between the core portion and the collar portion and / or the connection portion between the outer peripheral surface and the side surface of the core portion in the collar portion than a naturally occurring aspect in processing. Further, it is possible to prevent a crack from occurring at the boundary between the core part and the collar part, or a crack or a chip from occurring in the collar part.

  The other features of the present invention and the operational effects thereof will be described in more detail with reference to the accompanying drawings.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of a coil device according to the present invention will be described with reference to the accompanying drawings. In the drawings, the same reference numerals indicate the same or corresponding parts.

  FIG. 1 shows a longitudinal section of a coil device according to the present embodiment. The coil device 1 mainly includes a ferrite core 3, a coil 5, an insulating exterior body 7, and a pair of terminals 9 and 11. The coil device 1 is applied to, for example, a bidirectional keyless entry system that does not require a button operation, an anti-theft immobilizer, a tire pressure monitoring system, and the like in an automobile.

  The coil 5 includes a winding wound around the outer peripheral surface of the ferrite core 3 with the ferrite core 3 as a center. The insulating exterior body 7 is provided so as to cover the entire surfaces of the ferrite core 3 and the coil 5.

  As shown in FIGS. 2 and 3, the ferrite core 3 is a substantially rod-shaped member, and has flanges 13 and 15 at both ends in the longitudinal direction (X direction). , 15 has a winding core portion 17.

  A pair of V-shaped grooves 19 and 21 are formed on the outer end surfaces 13b and 15b opposite to the winding core side surfaces 13a and 15a in the pair of flange portions 13 and 15, respectively. The pair of grooves 19, 21 extends along the Y direction and opens at both end surfaces of the ferrite core 3 in the Y direction.

  A pair of corresponding terminals 9 and 11 are engaged with the pair of grooves 19 and 21 described above. Returning to FIG. 1, the pair of terminals 9 and 11 are metal plate-like members that are curved in a substantially U shape when viewed in the ZX longitudinal section. More specifically, a nonmagnetic and springy material such as a phosphor bronze plate or a stainless metal plate such as SUS 304-CSP can be used.

  The pair of terminals 9 and 11 has three flat portions formed by bending a plate-like member at two locations. Of the three plane parts, the first parts 23 and 25 and the third parts 31 and 33 extend along the XY plane, and the second parts 27 and 29 extend along the YZ plane. Yes. The first portions 23 and 25 penetrate the insulating exterior body 7. One ends of the first portions 23 and 25 are inserted into the corresponding pair of grooves 19 and 21 and are fixed by an adhesive 35. Further, a winding terminal 37 of the coil 5 is joined to the first portions 23 and 25 by soldering. The other ends of the first portions 23 and 25 are connected to the first bending portion 39.

  The second portions 27 and 29 extend between the first bending portion 39 and the second bending portion 41. Further, the second portions 27 and 29 are provided with through holes 43 for making the cross-sectional areas of the second portions 27 and 29 smaller than those of the first portions 23 and 25 and the third portions 31 and 33. . The third portions 31 and 33 extend from the second curved portion 37 toward the center in the core longitudinal direction and substantially parallel to the lower surface of the insulating exterior body 7.

  The insulating exterior body 7 is a substantially rectangular parallelepiped member that covers the ferrite core 3 and the coil 5. That is, the cross-sectional shape orthogonal to the coil winding axis direction (X direction) in the insulating exterior body 7 is formed in a quadrangular shape as in the existing surface mount type coil device. The insulating outer body 7 protects the ferrite core 3 and the coil 5, improves the bonding strength of the pair of terminals 9 and 11 with respect to the ferrite core 3, and realizes an aspect excellent in mechanical reliability. .

  Next, details of the ferrite core 3 will be described with reference to FIGS. 2, 3, and 4. Each of the pair of flange parts 13 and 15 and the core part 17 is formed so that the dimension in the Y direction is larger than the dimension in the Z direction. Further, the pair of flange portions 13 and 15 are formed to have a larger dimension in the Z direction and a larger dimension in the Y direction than the core portion 17. Thereby, in the pair of flange portions 13 and 15, the core portion side surfaces 13a and 15a exist so as to rise substantially vertically from the upper and lower surfaces and both side surfaces of the core portion 17, respectively.

  Each of the pair of flanges 13 and 15 is formed in a substantially rectangular parallelepiped shape, and corresponds to the winding core side surfaces 13a and 15a, the outer end surfaces 13b and 15b facing the core side surfaces 13a and 15a, and the surfaces 13a and 15a and the surfaces 13b and 15b. Outer peripheral surfaces connecting the sides to be connected, that is, upper surfaces 13c and 15c, lower surfaces 13d and 15d, and a pair of side surfaces 13e and 13f and 15e and 15f.

  The core portion 17 is between the pair of flange portions 13 and 15 and has an upper surface 61, a lower surface 63, and a pair of side surfaces 65 and 67. In particular, as shown in FIG. 4, the cross section of the core portion 17, that is, the cross section orthogonal to the axial direction (X direction) of the core portion 17 swells on a pair of opposed surfaces in a quadrangular shape indicated by a dotted line. It has a shape with a protruding portion 69.

  Thereby, in this Embodiment, a pair of side surfaces 65 and 67 are comprised by the bulging part 69 and the pair of flat part 71 currently formed in the both sides. In other words, the pair of flat portions 71 is formed between the bulging portion 69 and the upper surface 61 and the lower surface 63 which are a pair of opposed surfaces.

  In addition, the pair of bulging portions 69 are configured by curves as viewed in the cross section of FIG. 4, and are particularly configured by arcuate curves in the present embodiment. Further, the winding core portion 17 is provided with four winding escape portions 73. Each winding escape portion 73 is formed by being recessed inward from a virtual arcuate line L described later, as seen in the cross section of FIG. The arc-shaped line L is an imaginary line that is in contact with the bulging portion 69 and connects square corners E located on both sides of the bulging portion 69.

  Further, as shown in the enlarged portion (a) of FIG. 3, the R processing is performed on the connecting portion 75 between the upper surface 61 of the core portion 17 and the core portion side surfaces 13a and 15a of the pair of flange portions 13 and 15. Alternatively, taper processing is performed as shown in the enlarged portion (b) of FIG. Furthermore, R processing is given also to the connection part 77 of the core part side surfaces 13a and 15a of a pair of collar parts 13 and 15, and the upper surfaces 13c and 15c.

  As specific dimensions in the present embodiment, the X direction dimension of the core part 17 is 7 mm, the X direction dimensions of the flange parts 13 and 15 are 1.3 mm, and the core part side surfaces of the flange parts 13 and 15. The rising dimension in the Z direction from the core portion 17 in 13a and 15a is 0.5 mm. With respect to such a configuration, when the connection part 75 is R-processed, the radius of the R-processed part in the connection parts 75 and 77 is 0.15 mm. Incidentally, the radius of the natural R naturally occurring in the processing before the R processing according to the present embodiment is about 0.05 to 0.07 mm. Therefore, the radius of the R processed portion of the connecting portions 75 and 77 is about 2 to 3 times the natural R. On the other hand, when the connecting portion 75 is tapered, the inclination angle θ of the tapered portion of the connecting portion 75 is set to 30 to 60 ° with respect to the winding axis C of the winding core portion 17.

  The core portion 17 of the ferrite core 3 is manufactured by a known mode, that is, press molding by compressing ferrite powder. Press molding is performed using a pair of frame mold, upper mold and lower mold. A pair of frame molds are arranged so as to be spaced apart at a predetermined interval, and a ferrite powder is filled between the pair of frame molds, and the upper mold and the lower mold are inserted between the pair of frame molds from above and below. It is compression molded by the mold. The upper surface 61 and the lower surface 63 of the core part 17 are formed by a pair of frame molds, and the pair of side surfaces 65 and 67 of the core part 17 are formed by an upper mold and a lower mold.

  In the coil device having the above configuration, the following operation is obtained. A bulging portion 69 is formed on a pair of opposite side surfaces of the core portion 17. For this reason, when the winding of the coil 5 is wound around the winding core portion 17, the winding is wound in a shape closer to a circle than in the case where the bulging portion is not provided in the cross-sectional shape of FIG. 4. Therefore, even if the coil 5 expands due to heat when molding the insulating sheath 7, stress concentration is mitigated in the portion of the insulating sheath 7 that covers the winding of the corner E in the core portion 17. Thus, cracks can be prevented from occurring at the portion.

  In particular, when implemented as a vehicle-mounted transponder, the number of windings of the coil 5 increases, so that the winding expansion rate is large and the crack generation rate is higher. Therefore, the present invention is particularly effective when implemented as an in-vehicle transponder.

  Further, since the bulging portion 69 is formed of a curved line in the cross-sectional shape, it is possible to avoid the occurrence of new stress concentration due to the provision of the bulging portion 69.

  Furthermore, as described above, when using an insulating outer package having a square cross section as in the existing surface mount type coil device, and simultaneously using a winding core having a circular cross section, the insulating outer package There is a tendency that it is difficult to ensure the thickness of the body, or that the whole coil device is increased in size. However, in the present invention, when the bulging portion 69 is provided, the cross-sectional shape of the winding core portion is formed so as to have the bulging portions on a pair of opposing surfaces in the quadrangular shape, so that insulation is provided as described above. While preventing the occurrence of cracks in the outer package 7, it is possible to satisfy the demand for downsizing the coil device. In particular, the coil device can be made thin (low profile) by arranging the pair of side surfaces provided with the bulging portions 69 so as to be aligned with the lateral direction during mounting.

  Moreover, since the winding escape part 73 is formed in the core part 17, when the coil 5 expand | swells by the heat | fever at the time of molding the insulation exterior body 7 as mentioned above, a part of winding is It can enter into the winding escape portion 73, that is, can swell inside the arcuate line L. Therefore, the proportion of the expanded winding exerting an expansion force on the outer insulating outer body 7 is reduced correspondingly, and cracks are effectively generated even in the vicinity of the corner of the insulating outer body 7 where cracks are a problem. Could be prevented.

  In addition, the core part 17 is manufactured by compression molding of powder as described above. Normally, when the core part has an arc-shaped outer shape when viewed in a cross section, two adjacent molds have acute angles. There is a problem in that they are in contact with each other and a sufficient compressive force cannot be applied, or the mold is significantly damaged. That is, if the bulging portion of the winding core portion 17 bulges over the entire side surfaces 65 and 67 from the rectangular corner E, there is an acute angle relationship between the frame mold and the upper mold and the lower mold. Become.

  However, in the actual embodiment, the bulging portion 69 partially bulges on the side surfaces 65 and 67, that is, the flat portions 71 are formed on both sides of the bulging portion 69. The upper mold and the lower mold are in contact with each other at a substantially right angle. For this reason, it can prevent that a big compression reaction force acts on the edge part of a type | mold. Therefore, a sufficient compressive force can be applied, and damage to the mold in a short period can be prevented.

  Further, the connecting portion 75 between the upper surface 61 of the core portion 17 and the core portion side surfaces 13a and 15a of the flange portions 13 and 15, and the core portion side surfaces 13a and 15a of the flange portions 13 and 15 and the upper surfaces 13c and 15c, The connecting portion 77 is subjected to a larger R processing than that naturally occurring in processing. As a result, it is possible to prevent a crack from occurring at the boundary between the core portion 17 and the flange portions 13 and 15, and a crack or chipping from occurring in the flange portions 13 and 15. The occurrence of such cracks, cracks, and chips is caused by the fact that the coil 5 is surrounded by the insulating exterior body 7 when the coil 5 expands, and the expansion force acts on the coil 5 as a reaction force. . Therefore, in the embodiment in which the coil 5 is covered with the insulating exterior body 7 as in the present invention, it is particularly effective in preventing cracks, cracks and chips. Moreover, also in the aspect in which the connection part 75 of the upper surface 61 of the core part 17 and the core part side surfaces 13a and 15a of the collar parts 13 and 15 is taper-processed, the same effect as said R process can be acquired. .

  Although the contents of the present invention have been specifically described with reference to the preferred embodiments, various modifications can be made by those skilled in the art based on the basic technical idea and teachings of the present invention. It is self-explanatory.

  For example, in the above-described embodiment, the bulging portion 69 of the winding core portion 17 is configured with a continuous curve as viewed in its cross section, but the present invention is not limited to this and is discontinuous. You may comprise using the curve and the straight line partially.

  In addition to the keyless entry system, immobilizer, and air pressure monitoring system described above, the coil device 1 of the present invention is not limited to a vehicle-mounted antenna, and is not limited to an automobile, but as an antenna, transponder, or inductor as a general electronic component. It is also possible to use it.

It is a longitudinal section of a coil device concerning an embodiment of the invention. It is a perspective view of the ferrite core in a coil apparatus. It is a side view of the ferrite core in a coil apparatus. It is sectional drawing by the IV-IV line of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Coil apparatus 3 Ferrite core 5 Coil 7 Insulation exterior body 13, 15 collar part 17 Core part 71 Flat part 73 Winding escape part L Arcuate line E Corner part

Claims (4)

A coil device including a core, a coil provided around the core, and an insulating exterior body covering the core and the coil,
The core includes a core part for winding the winding of the coil, and a pair of flange parts formed at both ends of the core part,
Section perpendicular to the coil winding axis of the winding core portion is a rectangular shape, and, have a shape with a bulging portion on the pair of surfaces thereof facing,
The bulging portion of the winding core portion is configured by an arcuate curve in a cross section orthogonal to the coil winding axis direction,
The winding core portion is formed with at least one winding escape portion,
The winding escape portion is formed by being recessed inward from an arcuate line that is in contact with the bulging portion and connects the square corner portions on both sides of the bulging portion, as viewed in a cross section of the winding core portion. ing,
Coil device. The coil device according to claim 1 ,
The winding core portion has flat portions on both sides of the bulging portion,
The flat portion is formed between another pair of opposed surfaces in the rectangular shape and the bulging portion.
Coil device. The coil device according to claim 1 or 2 ,
R processing or taper processing is performed between the outer peripheral surface of the core portion and the surface of the flange portion on the core portion side.
Coil device. A coil device according to any one of claims 1乃Itaru 3,
R processing is performed between the surface on the core portion side and the outer peripheral surface on the radially outer side in the collar portion,
Coil device.

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