Patent Publication Number: US-10312005-B2

Title: Gapped core, coil component using same, and method for manufacturing coil component

Description:
TECHNICAL FIELD 
     The present invention relates to a core for use in coil components that are provided in rectification circuits, noise prevention circuits, resonant circuits and the like in AC devices such as power supply circuits and inverters, a coil component using the core, and a method for manufacturing the coil component. 
     BACKGROUND ART 
     A coil apparatus that is installed in the circuits of various AC devices includes a coil component consisting of a coil wound around an annular core. 
     In order to readily wind the coil around the core, a coil component has been proposed in which a core with an opening formed in a portion thereof is formed, a pre-wound air core coil is inserted through this opening, and thereafter a magnetic or nonmagnetic filler is used to backfill the opening and make the opening into a gap (e.g., see FIG. 10 of Patent Document 1). 
     In contrast, the applicant has proposed a gapless core in which a core pre-formed in an annular shape is cut at two places and a segment is cut out, the segment is fitted into a cutout part formed in the remaining C-shaped body, and respective end faces are abutted against each other (see Patent Document 2). 
     CITATION LIST 
     Patent Documents 
     [Patent Document 1] JP 2011-135091A 
     [Patent Document 2] JP 2013-244043A 
     SUMMARY OF INVENTION 
     Technical Problem 
     There was a problem regarding the gapless core proposed in Patent Document 2 in that the range for obtaining desired DC bias characteristics suitable for various types of power supply circuits is limited, since inductance and the magnetic saturation current are determined by the characteristics of the magnetic material. 
     An object of the present invention is to provide a gapped core that facilitates adjustment of DC bias characteristics, has little variation in these characteristics and also has excellent manufacturing efficiency, a coil component using this core, and a method for manufacturing the coil component. 
     Solution to Problem 
     A gapped core according to the present invention has a main body and a segment that are obtained by a molded core including an annular magnetic body made of a magnetic material and a resin covering part that covers the magnetic body being cut at a first cutting part and a second cutting part that transect an outer peripheral surface and an inner peripheral surface and approach each other in an inner peripheral direction of the molded core, the main body having a main body-side first end face formed by cutting at the first cutting part and a main body-side second end face formed by cutting at the second cutting part, and the segment having a segment-side first end face formed by cutting at the first cutting part and a segment-side second end face formed by cutting at the second cutting part, the segment being disposed in a cutout part formed between the main body-side first end face and the main body-side second end face of the main body, and the main body-side first end face and the segment-side first end face and/or the main body-side second end face and the segment-side second end face opposing each other across a gap. 
     A nonmagnetic spacer can be inserted between the main body-side first end face and the segment-side first end face and/or between the main body-side second end face and the segment-side second end face. 
     The spacer can be an attachment that couples a resin plate that is inserted between the main body-side first end face and the segment-side first end face and/or between the main body-side second end face and the segment-side second end face, at least at an inner peripheral side, an outer peripheral side or a lateral side of the segment. 
     The resin covering part can be configured to have a main body-side flange part that projects toward the outer peripheral side and/or the lateral side from an end edge on the main body-side second end face side, and a segment-side flange part that projects toward the outer peripheral side and/or the lateral side from an end face on the segment-side second end face side. 
     A coil component of the present invention is constituted by the segment being pushed into the cutout part, after inserting a pre-wound air core coil into the main body of the above gapped core through the cutout part. 
     A method for manufacturing a coil component of the present invention involves cutting a molded core including an annular magnetic body made of a magnetic material and a resin covering part that covers the magnetic body at a first cutting part and a second cutting part that transect an outer peripheral surface and an inner peripheral surface and approach each other in an inner peripheral direction of the molded core to obtain a main body having a main body-side first end face formed by cutting at the first cutting part and a main body-side second end face formed by cutting at the second cutting part, and a segment having a segment-side first end face formed by cutting at the first cutting part and a segment-side second end face formed by cutting at the second cutting part, inserting a pre-wound air core coil into the gapped core through a cutout part formed between the main body-side first end face and the main body-side second end face, and disposing the segment such that the main body-side first end face and the segment-side first end face oppose each other and the main body-side second end face and the segment-side second end face oppose each other, with a gap existing between at least one thereof. 
     Advantageous Effects of Invention 
     According to the present invention, by cutting the molded core at the first cutting part and the second cutting part, the total length of the main body and the segment is shortened by an amount of the cutting allowance. Accordingly, the cutting allowance can be made into a gap, simply by inserting the segment into the cutout part in the main body. 
     With the gapped core of the present invention, the main body and the segment are produced from the same molded core and thus have the same magnetic characteristics, enabling the gapped core that is produced and the coil component using this core to exhibit stable magnetic characteristics and the like. Also, forming a gap in the core enables the DC bias characteristics to be readily adjusted. 
     Furthermore, the main body and the segment do not need to be produced separately, and the segment that is cut out can be directly utilized, enabling manufacturing efficiency to be enhanced as much as possible, with almost no loss of raw materials. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a side view of a gapped core of the present invention. 
         FIG. 2  is a perspective view of the gapped core of the present invention. 
         FIG. 3  is a perspective view of a magnetic body. 
         FIG. 4  is a side view of a molded core before cutting. 
         FIG. 5  is a bottom view of the molded core before cutting. 
         FIG. 6  is a perspective view of the molded core before cutting. 
         FIG. 7  is a perspective view of the molded core before cutting as seen from the opposite side to  FIG. 6 . 
         FIG. 8  is a perspective view showing a process of coupling molded cores. 
         FIG. 9  is a perspective view showing a state in which molded cores are coupled. 
         FIG. 10  is a side view showing a process of cutting a molded core. 
         FIG. 11  is a perspective view showing a state in which the molded core has been cut into a main body and a segment. 
         FIG. 12  is a perspective view of an attachment that is mounted on the segment. 
         FIG. 13  is a perspective view showing a process of mounting the attachment on the segment. 
         FIG. 14  is a perspective view of a gapped core in which the segment with the attachment mounted thereon is mounted to the main body. 
         FIG. 15  is a cross-sectional view of a resin covering part of the gapped core. 
         FIG. 16  is a perspective view of the attachment of a different embodiment. 
         FIG. 17  is a perspective view showing a process of mounting the attachment of  FIG. 16  on the segment. 
         FIG. 18  is a perspective view of the gapped core in which the segment with the attachment of  FIG. 16  mounted thereon is mounted to the main body. 
         FIG. 19  is a perspective view showing a process of inserting an air core coil in the main body. 
         FIG. 20  is a perspective view showing a process of inserting the segment with the attachment mounted thereon into the main body in which the air core coil is inserted. 
         FIG. 21  is a perspective view of a core component in which the air core coil is fitted in the gapped core. 
         FIG. 22  is a perspective view of a casing for mounting the core component. 
         FIG. 23  is a plan view of the casing. 
         FIG. 24  is a side view of the casing. 
         FIG. 25  is a perspective view showing a process of mounting the core component to the casing. 
         FIG. 26  is a perspective view showing a state in which the core component is mounted to the casing. 
         FIG. 27  is a perspective view of a core apparatus according to the present invention. 
         FIG. 28  is a graph showing DC bias characteristics in a working example. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, after first describing a gapped core  10  with reference to the drawings, description will be given with regard to one embodiment of a coil component  50  that uses this gapped core  10  and a coil apparatus  55  in which the coil component  50  is mounted to a casing  70 . 
       FIG. 1  and  FIG. 2  are a plan view and a perspective view of the gapped core  10  according to one embodiment of the present invention. The gapped core  10  is constituted by a main body  30  in which a cutout part  31  (range shown by arrows in  FIG. 1 ) is formed in a portion thereof, and a segment  40  that fits into the cutout part  31  of the main body  30 . 
     As shown in  FIG. 1 , the segment  40  and the cutout part  31  of the main body  30  that results from the segment  40  being cut out are shaped such that respective abutting faces approach each other toward the inner peripheral surface of the main body  30 , that is, are substantially fan-shaped. The cutout part  31  of the main body  30  has a main body-side first end face  32  and a main body-side second end face  33  that form end faces, and the segment  40  has a segment-side first end face  42  and a segment-side second end face  43  that form end faces. 
     The segment  40  is inserted into the cutout part  31  of the main body  30  such that the main body-side first end face  32  and the segment-side first end face  42  oppose each other and the main body-side second end face  33  and the segment-side second end face  43  oppose each other. The main body-side first end face  32  and the segment-side first end face  42  and the main body-side second end face  33  and the segment-side second end face  43  oppose each other across gaps  11  and  11 , rather than abutting against each other. 
     The gapped core  10  having the above configuration can be produced in the following way. 
     First, a molded core  20  that includes a magnetic body  21  is produced. 
     The molded core  20  is obtained by covering the peripheral surface of the magnetic body  21  made of a magnetic material, as shown in  FIG. 3 , with an insulating resin covering part  22  as shown in  FIG. 4  to  FIG. 7 . 
     In  FIG. 3 , the cross-section of the magnetic body  21  is formed to be substantially rectangular, but the cross-sectional shape of the magnetic body  21  may be circular, elliptical or the like. 
     Also, the molded core  20  can employ a toroidal shape (circular ring shape), an elliptical ring shape, an oval ring shape, a rectangle ring shape, a teardrop shape, or the like.  FIG. 4  to  FIG. 7  show a toroidal molded core  20 . 
     As the magnetic material that is employed for the magnetic body  21 , an iron based, iron-silicon based, iron-aluminum-silicon based or iron-nickel based material or an iron based or Co based amorphous material can be given as examples. The magnetic body  21  can be configured as a powder compression molded body formed by compressing a powder made of a magnetic material, a molded body of a ferrite core formed by sintering a powder made of a magnetic material, or a laminated core formed by laminating or winding a thin plate made of a magnetic material. 
     Of these various magnetic materials, the powder compression molded body is favorably employed as the magnetic body  21 . This is due to the powder compression molded body having high dimensional accuracy and also high design flexibility. 
     On the other hand, when the magnetic body  21  composed of a powder compression molded body is cut using a cutting blade (grindstone), the peripheral surface may break up when the cutting blade is applied. In view of this, the molded core  20  can be favorably obtained by insert-molding the magnetic body  21  composed of a powder compression molded body using an insulating resin and forming the resin covering part  22  on the peripheral surface of the magnetic body  21  such as shown in  FIG. 4  to  FIG. 7 . The magnetic body  21  can thereby be prevented from breaking up during cutting. Note that the molded core  20  can also be produced by a resin powder coating method. 
     On the resin covering part  22 , a flange part  23  that projects toward the outer peripheral side and/or the lateral side is formed in a position corresponding to the abovementioned main body-side second end face  33  and segment-side second end face  43 . The flange part  23  defines the cutting position as well as serving as a holding part for positioning and fixing a jig of a cutting apparatus, when cutting the molded core  20 . Also, as will be discussed later, the flange part  23  is used in order to couple the coil components  50  together, when aligning and collectively cutting the coil components  50 . 
     The flange part  23  forms a main body-side flange part  25  and a segment-side flange part  27  after being cut, with the main body-side flange part  25  serving to position the jig when inserting an air core coil  51  and to retain the air core coil  51 . Also, the segment-side flange part  27  serves to retain the air core coil  51  when the segment  40  has been mounted to the main body  30 . Furthermore, the main body-side flange part  25  and the segment-side flange part  27  can be used to position and fix the casing  70 , when mounting the coil component  50  to the casing  70 . 
     More specifically, the flange part  23  projects to the outer peripheral side from the resin covering part  22 , as well as projecting to the lateral side. On the outer peripheral side of the flange part  23 , a main body-side latch part is formed on the side that will become the main body-side flange part  25 . The main body-side latch part in the drawings is a groove  25   a  formed in the width direction of the main body-side flange part  25 . 
     Also, on the lateral side of the flange part  23 , main body-side engaging parts, one of which is a recessed section  25   b  and the other of which is a protruding section  25   c , are formed on the side that will become the main body-side flange part  25 . These main body-side engaging parts engage the main body-side engaging parts of adjacent coil components  50  when collectively cutting the coil components  50 , and act to position and prevent rotation of the coil components  50 . 
     On the inner side of the resin covering part  22 , a coupling member  28  that extends on the inner peripheral side of the molded core  20  projects on the opposite side to the above mentioned main body-side flange part  25 , that is, so as to be continuous with the main body-side second end face  33 . The coupling member  28 , as shown in  FIG. 8  and  FIG. 9 , engages the adjacent coil component  50  and acts to position the coil components  50 , when aligning and collectively cutting the coil components  50 . For example, one face of the coupling member  28  can be configured as a protruding shaft  28   a  (see  FIG. 7 ) at the tip that extends to the middle of the molded core  20 , and the other face can be configured as a shaft hole  28   b  into which the protruding shaft  28   a  fits. 
     Also, a plurality of holes  24  are formed in the side surface of the resin covering part  22 . These holes are formed by insert pins for positioning the molded core  20  in the mold during insert-molding. These holes  24  can be utilized in mounting an attachment  60  which will be described later. 
     Furthermore, as shown in  FIG. 4  to  FIG. 6 , a plurality of ribs  29  project from one side surface of the resin covering part  22 . In the drawings, three ribs  29  project from the resin covering part  22 . These ribs  29 , as shown in  FIG. 8  and  FIG. 9  which will be discussed later, act as spacers that secure an interval between molded cores  20  when collectively cutting the molded cores  20 . 
     Note that, desirably, at least one rib  29  each is formed on the main body  30  side and the segment  40  side. In the drawings, there are two ribs  29  on the main body  30  and one rib  29  on the segment  40 . 
     The ribs  29  are only utilized when collectively cutting the molded cores  20 , and are not required in the production or configuration of the coil component  50  after cutting. Accordingly, the ribs  29  need to be removed after cutting the molded core  20 . In view of this, the ribs  29  are desirably configured such that the area around the ribs  29  is thinly formed, enabling the ribs  29  to be excised simply by being obliquely pushed lightly with a finger. 
     Also, as shown in  FIG. 7 , in the resin covering part  22 , fitting holes  29   a  into which the ribs  29  fit are provided in the surface on the opposite side to the ribs  29 . Fitting the ribs  29  of the adjacent molded core  20  into the fitting holes  29   a , when collectively cutting the molded cores  20 , thereby enables the molded cores  20  to be positioned, in addition to securing an interval between the molded cores  20 . 
     The molded core  20  having the above configuration is cut in two places, as shown in  FIG. 10  and  FIG. 11 , using a cutting blade, and the main body  30  and the segment  40  are separated. Although cutting of the molded cores  20  can also be implemented one at a time, working efficiency is enhanced as much as possible by a plurality of molded cores  20  being coupled side-by-side and collectively cut. 
     In this case, first, the molded cores  20  are coupled. More specifically, as shown in  FIG. 8  and  FIG. 9 , a plurality of molded cores  20  are aligned side-by-side, with the recessed section  25   b  of the flange part  23  of the molded cores  20  engaged with the protruding section  25   c  of the flange part  23  of the adjacent molded core  20 , and the protruding shaft  28   a  of the coupling member  28  engaged with the shaft hole  28   b . At this time, the ribs  29  abut against the side surface of the adjacent molded core  20 , and an interval is secured therebetween. Note that in the case where the fitting holes  29   a  are formed in the resin covering part  22 , this configuration is also useful in positioning of the molded cores  20 , by fitting the ribs  29  into the fitting holes  29   a  of the adjacent molded core  20 . 
     In the drawings, in order to facilitate description, two molded cores  20  are coupled side-by-side, but as long as there is more than one, the present invention is not limited to two. It is favorable to couple and collectively cut five to ten molded cores  20 . 
     The cutting blade is inserted into the molded cores  20  that are arranged side by side, and the molded cores  20  are cut, as shown in  FIG. 10  and  FIG. 11 . Cutting is implemented in two places, namely, a first cutting part  26 A and a second cutting part  26 B, such that the molded core  20  is separated into the main body  30  and the segment  40  as a result of the cutting. The second cutting part  26 B is implemented in the flange part  23 . Cutting at the first cutting part  26 A and the second cutting part  26 B can also be implemented at the same time, or one may be cut, followed by cutting the other. Desirably, the first cutting part  26 A and the second cutting part  26 B form an angle of less than or equal to 90 degrees, and the illustrated embodiment is implemented such that the cutting parts form an angle of 80 degrees. Note that although illustration of the ribs  29  is omitted in  FIG. 10  and  FIG. 11 , there is a risk, when the molded core  20  is cut, that the segment  40  will drop out after cutting is completed. Accordingly, it is desirable, during cutting, to grip the ribs  29  with a jig or the like to prevent the segment from dropping out, particularly when performing the second cut. 
     The molded core  20  can be cut using a rotating cutting blade or the like. A metal-bonded diamond wheel can be given as an example of the cutting blade. When cutting the molded core  20 , cutting cannot be performed with a zero cutting allowance, and a cutting allowance that depends on the thickness of the cutting blade is required. In other words, the segment  40  is reduced in size by the amount of the cutting allowance, relative to the cutout part  31  of the main body  30  formed by cutting the molded core  20  and cutting out the segment  40 . This cutting allowance corresponds to the gap  11 . Accordingly, a cutting blade having a blade thickness that conforms to the width of the gap  11  need only be employed. Desirably, a cutting blade having a blade thickness of 0.5 mm to 1.2 mm or a thin blade of less than 0.7 mm in thickness is favorably used. 
     Note that the gaps  11  and  11  can be made the same width, but may also be different widths. In this case, cutting blades having different blade thicknesses according to the gap widths need only be at the first cutting part  26 A and the second cutting part  26 B. 
     Also, in the case where the gap  11  is provided between the main body-side first end face  32  and the segment-side first end face  42  and between the main body-side second end face  33  and the segment-side second end face  43 , the influence on inductance can be reduced even when the surface roughness of the end faces is degraded compared with a configuration in which the end faces are placed directly against each other. Accordingly, there is an advantage in that the speed with which the cutting blade cuts the molded core  20  is increased, enabling the efficiency of the cutting operation to be improved. 
     As a result of the cutting, the molded core  20  is separated into the main body  30  having the cutout part  31  formed by cutting out the segment  40  and the substantially fan-like segment  40 . 
     As shown in  FIG. 11 , the main body  30  formed by cutting out the segment  40  is a substantially C-shaped member having the main body-side first end face  32  formed by cutting at the first cutting part  26 A and the main body-side second end face  33  formed by cutting at the second cutting part  26 B, and in which is formed the cutout part  31  having an interval equal to the amount of the segment  40  that was cut out and the cutting allowance, between the main body-side first end face  32  and the main body-side second end face  33 . In the cutout part  31 , the main body-side first end face  32  and the main body-side second end face  33  approach each other in the inner peripheral direction, and the angle formed by the main body-side first end face  32  and the main body-side second end face  33  is the same as the angle formed by the first cutting part  26 A and the second cutting part  26 B toward the inner peripheral side of the molded core  20 . 
     As similarly shown in  FIG. 11 , the segment  40  is also a substantially fan-shaped member having the segment-side first end face  42  formed by cutting at the first cutting part  26 A and the segment-side second end face  43  formed by cutting at the second cutting part  26 B, and in which the segment-side first end face  42  and the segment-side second end face  43  approach each other in the inner peripheral direction. The angle formed by the segment-side first end face  42  and the segment-side second end face  43  of the segment  40  is the same as the angle formed by the first cutting part  26 A and the second cutting part  26 B toward the inner peripheral side of the molded core  20 . 
     After cutting the molded core  20 , the ribs  29 , which are no longer required, are excised. The ribs  29  can be readily excised simply by being obliquely pushed lightly with a finger, due to the periphery thereof being thinly formed. The main body  30  and the segment  40  with the ribs  29  excised are shown in the aforementioned.  FIG. 1  and  FIG. 2 . 
     The gapped core  10  in which the cutting allowance forms the gap  11  can be obtained, as shown in  FIG. 1  and  FIG. 2 , by inserting the segment  40  into the cutout part  31 , with respect to the obtained main body  30 . 
     In the gapped core  10 , the gap  11  can be secured by inserting a nonmagnetic spacer between the main body  30  and the segment  40 . 
     For example, the spacer, as shown in  FIG. 12  or  FIG. 13 , can be integrated with the segment  40 , by being made into the shape of an attachment  60  that couples two resin plates  61  and  61  that abut against the segment-side first end face  42  and the segment-side second end face  43  of the segment  40  along the inner peripheral side and the lateral side of the segment  40 , enabling handling of the segment  40  to be facilitated. At this time, although illustration is omitted, a boss that fits into the hole  24  of the segment  40  that is formed by an insert pin projects from the inner side surface of the attachment  60 , and the attachment  60  can be readily mounted on the segment  40  by fitting the boss into the hole  24 . 
       FIG. 14  shows a perspective view in which the segment  40  to which the attachment  60  is attached from the inner peripheral side is mounted to the main body  30 , and  FIG. 15  shows a cross-sectional view of the resin covering part  22 . Referring to  FIG. 15 , it is evident that the resin plates  61  and  61  are interposed in positions where the end faces of the main body  30  and the segment  40  oppose each other. 
     Note that in the case of mounting the attachment  60  on the outer peripheral side of the segment  40 , the segment-side flange part  27  will be get in the way, and thus a configuration need only be adopted in which, in the attachment  60 , a resin plate  61  that abuts the segment-side first end face  42  is integrally formed so as to cover the outer peripheral side and the lateral side of the segment  40  as shown in  FIG. 16  to  FIG. 18 , and, at the segment-side second end face  43 , the gap  11  is secured by separately adhering a resin plate or with an interval holding member  76  of the casing  70  which will be discussed later. 
     Also, the attachment  60  can be readily mounted on the segment  40 , by configuring the side surface of the attachment  60  such that a boss  63  fits into a hole  24  formed in the segment  40  by an insert pin, as shown in  FIG. 16  to  FIG. 18 . Also, the segment  40  can be readily mounted to the main body  30 , by adopting a configuration in which the attachment  60  extends beyond the segment-side first end face  42 , a boss  63  is formed on the inner surface thereof, and the boss  63  fits into a hole  24  formed in the main body  30  by an insert pin. 
     Because the segment  40  is cut out from the main body  30 , the main body  30  and the segment  40  possess the same magnetic characteristics and the like. Accordingly, magnetic characteristics and the like that are extremely stable compared with the case where the segment is formed from a different member can be exhibited. 
     Furthermore, because the segment  40  cut out from the molded core  20  is put back in the cutout part  31  of the main body  30 , the process of forming a segment from a different member can be rendered unnecessary, and, in addition, manufacturing efficiency can be enhanced as much as possible, with almost no loss of raw materials. 
     Also, the width of the gap  11  can be adjusted by the thickness of the cutting blade. 
     A method for manufacturing a coil component  50  that utilizes the above gapped core  10  will be described. First, after cutting out the segment  40  from the molded core  20  ( FIG. 11 ), the pre-wound air core coil  51  is inserted from the main body-side first end face  32  of the main body  30 .  FIG. 19  shows a state in which the air core coil  51  is inserted in the main body  30 . 
     Note that in the case of using a coil insertion apparatus when inserting the air core coil  51  into the main body  30 , the main body  30  can be fixed so as to not be rotatable, by positioning the protruding shaft  28   a  (see  FIG. 7 ) and the shaft hole  28   b  of the coupling member  28  in the apparatus, and holding the main body-side flange part  25  with a jig. The air core coil  51  can be inserted in this state. The main body-side flange part  25  projects from the main body  30 , and thus serves to retain the air core coil  51 . 
     The coil component  50  is produced by the segment  40  with the attachment  60  mounted thereon being inserted into the cutout part  31  of the main body  30  and fixed, as shown in  FIG. 20  and  FIG. 21 , after the air core coil  51  has been inserted into the main body  30 . Note that  FIG. 20  and  FIG. 21  show exemplary insertion of the segment  40  with the attachment  60  shown in  FIG. 12  to  FIG. 15  mounted thereon. The segment  40  can be fixed to the main body  30 , by respectively applying an adhesive to the resin plates  61  and  61  (spacers) of the attachment  60  that oppose the main body-side first end face  32  and the main body-side second end face  33 . 
     In the case of not using the attachment  60 , the segment  40  need only be inserted into the cutout part  31  of the main body  30  after respectively adhering and fixing the resin plates  61  and  61  as spacers to the segment-side first end face  42  and the segment-side second end face  43  of the segment  40 . 
     According to the above description, the main body  30  and the segment  40  are annular, and, as shown in  FIG. 21 , form the wound coil component  50  of the air core coil  51 . 
     The coil component  50  that is produced is mounted to the casing  70 , which is for mounting to a substrate or the like, to form a coil apparatus  55  such as shown in  FIG. 27 . 
       FIG. 22  to  FIG. 24  show the casing  70  to which the coil component  50  is mounted. The casing  70  is constituted by a base  71  that becomes lower toward the center in conformity with the outer peripheral shape of the coil component  50  serving as a substrate. 
     The middle of the base  71  has walls whose side surfaces project upward, and on the inner surfaces of these walls is formed a flange fixing part for mounting the main body-side flange part  25  and the segment-side flange part  27  of the coil component  50 . The flange fixing part, in the present embodiment, is a recess  72 . The main body-side flange part  25  and the segment-side flange part  27  are inserted into this recess  72  and fixed. 
     A guide  73  that guides the side surfaces of the main body-side flange part  25  and the segment-side flange part  27  is recessed on both sides of the recess  72 , and pressing pieces  74  and  74  that inwardly press the main body-side flange part  25  and the segment-side flange part  27  project from surfaces opposing the main body-side flange part  25  and the segment-side flange part  27 . The pressing pieces  74  and  74  that are illustrated are two protruding sections parallel to the insertion direction of the main body-side flange part  25  and the segment-side flange part  27 . 
     Furthermore, a casing-side latching part that engages the main body-side latch part that is formed on the main body-side flange part  25  projects from the inner surface of the recess  72 . In the case where the main body-side latch part is the groove  25   a , the casing-side latching part can be configured as a latching piece  75  that projects so as to fit into the groove  25   a.    
     Also, a space occurs between the main body-side flange part  25  and the segment-side flange part  27  as a result of configuring the gap  11 . An interval holding member  76  that fits into this space and maintains the interval between the main body-side flange part  25  and the segment-side flange part  27  projects in the recess  72 . 
     Also, in the casing  70 , holding means  77  and  77  that hold leader lines  52  and  52  (see  FIG. 27 ) of the air core coil  51  project from the side surface of the base  71 . The holding means  77  is equipped with insertion parts  77   a  and  77   a  that each curve inwardly and have elasticity, and a receiving part  77   b  that passes the leader line  52  between the tips of these insertion parts  77   a  and  77   a  and holds the leader line  52 . As a result of inserting the leader line  52  between the insertion parts  77   a  and  77   a , the insertion parts  77   a  and  77   a  elastically deform to allow the leader line  52  to pass through, and the leader line  52 , having passed through the insertion parts  77   a  and  77   a , fits between the tips of insertion part  77   a  and  77   a  and the receiving part  77   b  and is held. 
     The coil apparatus  55  is formed as shown in  FIG. 26 , by mounting the coil component  50 , as shown in  FIG. 25 , to the casing  70  having the above configuration. The coil component  50  is attached to the casing  70  by inserting the main body-side flange part  25  and the segment-side flange part  27  into the recess  72  which serves as the flange fixing part. More specifically, by pushing both sides of the main body-side flange part  25  and the segment-side flange part  27  through the guide  73 , the main body-side flange part  25  and the segment-side flange part  27  fit into the recess  72 , and are inserted while being pressed by the pressing pieces  74  and  74 . Also, the interval holding member  76  projecting from the bottom surface of the recess  72  fits between the main body-side flange part  25  and the segment-side flange part  27 . 
     As a result of the groove  25   a , which is the main body-side latch part that is formed in the main body-side flange part  25 , fitting into the latching piece  75 , which is the casing-side latching part, the coil component  50  is prevented from dropping out into the casing  70 . 
     Next, the coil apparatus  55  can be obtained, as shown in  FIG. 27 , by respectively inserting the leader lines  52  and  52  of the air core coil  51  into the holding means  77  and  77 . 
     The above description is for describing the present invention, and should not be understood as limiting the described invention to the claims or restricting the scope thereof. Also, the configuration of each element of the present invention is not limited to the above embodiment, and can of course be variously modified within the technical scope defined by the claims. 
     For example, in the case of producing a plurality of molded cores  20  having the same shape, the segment  40  can also be put back in another main body  30 , rather than being put back in the main body  30  from which the segment  40  was cut out. 
     Also, although, in the above embodiment, a configuration is adopted in which the main body-side first end face  32  and the segment-side first end face  42  are opposed to each other and the main body-side second end face  33  and the segment-side second end face  43  are opposed to each other, a configuration may be adopted in which the main body-side first end face  32  and the segment-side second end face  43  are opposed to each other and the main body-side second end face  33  and the segment-side first end face  42  are opposed to each other. 
     In addition, although, in the above embodiment, the gaps  11  and  11  are respectively provided between the main body-side first end face  32  and the segment-side first end face  42  and between the main body-side second end face  33  and the segment-side second end face  43 , a configuration may be adopted in which the gap  11  is formed between only two of the end faces, and the other two end faces are placed against each other without a gap. 
     For example, by adopting a configuration in which the main body-side first end face  32  and the segment-side first end face  42  are placed against each other without a gap and the gap  11  is provided between the main body-side second end face  33  and the segment-side second end face  43 , the occurrence of leakage magnetic flux within the coil  51  can be suppressed. As a result, magnetic flux linked with the coil  51  decreases, enabling eddy current loss to be reduced and heat generation to be suppressed. 
     Also, by adopting a configuration, opposite to the above, in which the main body-side second end face  33  and the segment-side second end face  43  are placed against each other without a gap, and the gap  11  is provided between the main body-side first end face  32  and the segment-side first end face  42 , initial inductance decreases and there is a drop in saturation magnetic characteristics, but there is an advantage in that the slope of the DC bias characteristics can be reduced. 
     Working Example 
     plurality of powder compression molded bodies were produced from an Fe-nickel based alloy powder as the magnetic body  21 , and a molded core  20  in which the resin covering part  22  was formed by insert-molding was obtained. The magnetic body  21  was formed in a toroidal shape having a cross-section of 9.8 mm in width and 25 mm in height, with the outer diameter being 40 mm. 
     In an invention example 1, resin plates  61  and  61  (spacers) having an interval of 0.5 mm were inserted between the main body  30  and the segment  40 , and gaps  11  and  11  of 0.5 mm in width were formed. An invention example 2 is a working example in which one of the gaps  11  was set to 0.5 mm and the other gap  11  was set to 1.0 mm by changing the cutting blade thickness. Note that, for comparison, a reference example in which the segment was pushed into the main body with a method similar to Patent Document 2 without a gap was produced. 
     DC bias currents of 0 to 30 A were sent to the obtained invention examples and comparative example, and the DC bias characteristics were investigated. The results are shown in  FIG. 28 . Referring to the diagram, it is evident that providing the gap  11  lowers initial inductance, enabling the change in inductance to be reduced to a high current region, compared with the reference example. That is, it is evident that a desired inductance can be obtained and the DC bias characteristics can be favorably adjusted as a result of the gap  11 . 
     LIST OF REFERENCE NUMERALS 
     ( 10 ) Gapped core 
     ( 11 ) Gap 
     ( 20 ) Molded core 
     ( 25 ) Main body-side flange part 
     ( 27 ) Segment-side flange part 
     ( 30 ) Main body 
     ( 31 ) Cutout part 
     ( 32 ) Main body-side first end face 
     ( 33  Main body-side second end face 
     ( 40 ) Segment 
     ( 42 ) Segment-side first end face 
     ( 43 ) Segment-side second end face 
     ( 50 ) Coil component 
     ( 51 ) Air core coil 
     ( 55 ) Coil apparatus 
     ( 70 ) Casing