Abstract:
Disclosed is a magnetic element that makes it possible to prevent a coil terminal from being positioned on a ring mount. The magnetic element comprises a first core member, coils, which are disposed in a second core member and a bobbin, and a first mount, on which the first core member is mounted, and possesses a second mount, which is disposed rising up from, and positioned between both edges of, the first mount, and on which the second core member is mounted, and is further equipped with a base, with multiple terminals disposed protruding from the sides thereof. Furthermore, a protrusion is disposed at the edge of the second mount, extending in the direction moving away from said second mount, and this protrusion is smaller than the thickness dimension of the base, and a terminal is positioned on the back surface of the protrusion on the opposite side from the side on which the second core member is mounted, and then bound to the terminals.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to a magnetic element to be used for various electronic devices. 
       BACKGROUND 
       [0002]    Some of various magnetic elements include a drum core, a ring core, as well as a base made of a resin material and the like. Patent Document 1 discloses an example of such kind of magnetic element. In the meantime,  FIG. 8  shows a perspective view of a magnetic element  100  of that kind (in the figure, a ring core is dismounted). The magnetic element  100  shown in the figure is a transformer, in which a coil end part  121  of a coil  120  is wound on each of two of a plurality of terminals  111  located at a nearer side as well as two of a plurality of terminals  111  located at a further side. 
       PRIOR ART DOCUMENT 
     Patent Document 
       [0000]    
       
         Patent Document 1: JP-UM-H01-163306 
       
     
       SUMMARY OF INVENTION 
     Problem to be Solved 
       [0004]    As shown in  FIG. 8 , when a coil end part  121  of a coil  120  is wound on a terminal  111 , the coil end part  121  (a lead wire) of the coil  120  extends from part of a drum core  130  where the coil  120  is placed (hereafter, the part is deemed to be a bobbin  131 ), toward part of a base  110  where a ring core is installed (hereafter, the part is deemed to be a ring mount portion  112 ). If the ring core is installed onto the ring mount portion  112  under the condition described above, the coil end part  121  may be located at the ring mount portion  112  and/or the coil end part  121  may interfere with the ring core. 
         [0005]    In a case where the coil end part  121  is located at the ring mount portion  112 , the coil end part  121  is pinched between the ring core and the ring mount portion  112 . Meanwhile, in a case where the coil end part  121  and the ring core interfere with each other, it becomes difficult to appropriately install the ring core onto the ring mount portion  112 . In either case, the ring core cannot be located at a correct position since the ring core becomes tilted, unstable, and the like. In other words, it is necessary to install the ring core onto the ring mount portion  112  while preventing the coil end part  121  from being positioned on the ring mount portion  112  under the condition of a structure shown in  FIG. 8 . Therefore, the installation work under the condition requires additional man-hours, and namely the coil end part  121  interferes with the installation work of the ring core. 
         [0006]    The present invention has been made in view of the above-mentioned problems, and an object thereof is to provide a magnetic element which can prevent the coil end part from being positioned on the ring mount portion. 
       Means to Solve the Problem 
       [0007]    To achieve the object described above, a first aspect of the present invention is that; a magnetic element according to the present invention includes: a first core member having a bobbin; a second core member so placed as to face the first core member in a whole range around an outer circumference of the first core member; a coil placed by winding a lead wire and placed at the bobbin; and a base having a first mount portion for placing the first core member, a second mount portion for placing the second core member and being raised higher than the first mount portion and positioned between both end portions, and a plurality of terminals protruding from a side of the base; wherein the end portion of the second mount portion has a protrusion lengthening in a direction apart from the second mount portion, and the protrusion is sized smaller than the thickness of the base; and a coil end part of the coil is wound on the terminal after the coil end part of the coil is placed at a reverse surface of the protrusion opposite to a side for placing the second core member. 
         [0008]    According to a structure described above, the coil end part is situated on the reverse surface of the protrusion, and therefore this arrangement of the structure makes it possible to prevent the coil end part from being positioned on the second mount portion. Accordingly, it is possible to prevent the coil end part from pinching between the second core member and the second mount portion, and this arrangement makes it possible to prevent the second core member from becoming tilted, unstable, and so on. As a result, the second core member can precisely be positioned. Furthermore, since it is possible to prevent the coil end part from being positioned on the second mount portion, installation of the second core member onto the second mount portion can be carried out easily, and therefore an increase in working man-hours can be suppressed. 
         [0009]    In the invention described above, another aspect of the magnetic element according to the present invention is that; preferably the end of the second mount portion in the base should have a concave portion recessed in a direction toward the opposite side of the base, and the protrusion is provided in a state of covering over the concave portion from the side for placing the second core member. 
         [0010]    According to a structure described above, the coil end part is placed into the concave portion. Furthermore, since the coil end part is situated at the reverse surface of the protrusion, a bend of the coil end part can be so positioned as to be closer toward a center side in a radial direction, in comparison with a case where the concave portion is not provided. Thus, it becomes possible effectively to prevent the coil end part from becoming an obstacle for placement of the second core member. 
         [0011]    Another aspect of the magnetic element according to the present invention is that; preferably the first core member is provided with a locating protrusion protruding in a direction toward a side of the base, while the first mount portion of the base is provided with an recessed portion into which the locating protrusion fits. 
         [0012]    According to a structure described above, as the locating protrusion fits into the recessed portion, the first core member is positioned with respect to the base. Thus, the first core member can be precisely positioned with respect to the base so that the magnetic element is able to have stable characteristics. 
         [0013]    Another aspect of the magnetic element according to the present invention is that; preferably the second core member should have a clearance portion where an inner diameter of an open portion of the second core member at a lower side for placing the second core member onto the second mount portion is formed to be larger in comparison with an inner diameter of the open portion at a upper side. 
         [0014]    According to a structure described above, the coil end part can be easily led into the concave portion from the bobbin through the clearance portion. Therefore, the coil end part can be easily wound on the terminal while being positioned with the protrusion at the concave portion. 
       Advantageous Effect of the Invention 
       [0015]    According to the present invention, it is possible to prevent a lead wire from being positioned on a ring mount portion. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]      FIG. 1  is a perspective view showing a structure of a magnetic element according to an embodiment of the present invention. 
           [0017]      FIG. 2  is a perspective view showing a structure of a section, excluding a ring core, of the magnetic element of  FIG. 1 . 
           [0018]      FIG. 3  is a cross sectional view of the magnetic element of  FIG. 1 , taken along an X-Z plane passing through a center of a drum core. 
           [0019]      FIG. 4  is another cross sectional view of the magnetic element of  FIG. 1 , taken along an Y-Z plane passing through a center of a drum core. 
           [0020]      FIG. 5  is a perspective view showing a structure of a base of the magnetic element of  FIG. 1 . 
           [0021]      FIG. 6  is a bottom plan view showing the structure of the base of the magnetic element of  FIG. 1 . 
           [0022]      FIG. 7  shows positional relationships of a protrusion, a lead wire, a terminal, a ring core, and so forth in the magnetic element of  FIG. 1 . 
           [0023]      FIG. 8  is a perspective view showing a structure of a conventional type of drum core. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0024]    A magnetic element  10  according to an embodiment of the present invention is described below with reference to  FIG. 1  through  FIG. 7 . 
         [0025]    As shown in  FIG. 1  and so on, the magnetic element  10  according to the present embodiment is a transformer, and it includes a drum core  20 , a coil  30 , a ring core  40 , and a base  50 . The drum core  20  of these components corresponds to a first core member. As shown in  FIG. 2  through  FIG. 4 , the drum core  20  includes an upper flange portion  21 , a column portion  22 , and a lower flange portion  23 . Each of the upper flange portion  21 , the column portion  22 , and the lower flange portion  23  is provided so as to be circular in its plane view. In the present embodiment, the upper flange portion  21  of the drum core  20  is provided so as to have the same diameter as the lower flange portion  23 . Moreover, in the present embodiment, the upper flange portion  21  and the lower flange portion  23  have the comparably-sized thickness in their dimensions. 
         [0026]    In the drum core  20 , an area surrounded by the upper flange portion  21 , the column portion  22 , and the lower flange portion  23  works as a bobbin  24  (Refer to  FIG. 3  and  FIG. 4 ); and a coil  30  can be formed by winding a lead wire  31  there. Moreover, since the magnetic element  10  in the present embodiment is a transformer, a primary coil  30 A (an inner side of the coil  30 ) and a secondary coil  30 B (an outer side of the coil  30 ) are wound on the bobbin  24 , as shown in  FIG. 3  and  FIG. 4 . In the following explanation, the two coil sections are simply referred to collectively as the coil  30 , in a case where it is not needed to distinguish the primary coil  30 A from the secondary coil  30 B. 
         [0027]    In the present embodiment, a locating protrusion  23   b  protrudes downward from a side of a bottom surface  23   a  of the lower flange portion  23 , as shown in  FIG. 3 ,  FIG. 4 , and so on. The locating protrusion  23   b  fits into a recessed portion  58  of the base  50  to be described later, and the drum core  20  is with respect to the base  50 . Thus, the drum core  20  can be precisely located with respect to the base  50 , and therefore the magnetic element  10  can have stable characteristics. 
         [0028]    In the meantime, the ring core  40  corresponds to a second core member. As shown in  FIG. 1 ,  FIG. 3 ,  FIG. 4 , and so on, the ring core  40  is a core member so formed as to be seen as a circular ring in its overhead view, and it is possible for the drum core  20  described above to be situated at an open portion  41  of the ring core  40 . As shown in  FIG. 4 , the height ‘Hr’ of the ring core  40  is provided to be shorter than the height ‘Hd’ of the drum core  20 . Alternatively, the height ‘Hr’ may be larger than the height ‘Hd’, or their heights may be even the same. 
         [0029]    With regard to the open portion  41 , a dimension in a radial direction at a lower side is provided to be larger than that at an upper side, as shown in cross-sectional views of  FIG. 3  and  FIG. 4 . In other words, there is a clearance portion  44  formed in the ring core  40 ; wherein a dimension of a core part  42  in a radial direction becomes smaller as an elevation shifts downward from a halfway position in a height direction, and the dimension becomes constant in a range from a certain position to a bottom end. Owing to the clearance portion  44 , a coil end part  32  of the coil  30  is easily led to a concave portion  55 , to be described later, from the bobbin  24  through the clearance portion  44 . Therefore, the coil end part  32  of the coil  30  is easily wound on a terminal  51 , while being located at a protrusion  56  of the concave portion  55 , to be described later. 
         [0030]    A cutout portion  43  is provided upwardly from a downward direction in the ring core  40 . The cutout portion  43  is a portion provided for pulling out the coil end part  32  of the coil  30  toward the terminal  51 . The cutout portion  43  is placed so as to face a side of the base  50  (an end of the base  50  in a short hand direction) where terminals  51  in plural are laid out in line. 
         [0031]    Furthermore, the drum core  20  and the ring core  40  are made of magnetic materials; and as the magnetic materials, it is possible to use various kinds of ferrite, such as Ni-based ferrite, Mn-based ferrite, and so forth permalloy, sendust, and the like. 
         [0032]    In the meantime, the base  50  is made of a nonmagnetic material, such as a resin, and the like; while including a plurality of terminals  51  embedded in it. As shown in  FIG. 5 , each of the terminals  51  has a board connector  51   a  that protrudes downward further than a bottom surface  50   a  of the base  50 . Then, at the time when the magnetic element  10  is mounted on a board, the board connector  51   a  makes contact with the board. 
         [0033]    As shown in  FIG. 5 ,  FIG. 6 , and so on, the base  50  includes a drum mounting portion  52 , a ring mounting portion  53 , an outer circumference wall  54 , the concave portion  55 , and the protrusion  56  as other components of the embedded terminals  51 . In all these components, the drum mounting portion  52  corresponds to a first mount portion, and it is a lowest height part in an upper surface side of the base  50 , where the drum core  20  is placed. A first circumference wall  57 , which is a boundary between the drum mounting portion  52  and the ring mounting portion  53 , is provided so as to be almost circular in its overhead view. A distance in a radial direction from a center position of the drum mounting portion  52  to the first circumference wall  57  (i.e., corresponding to a radius) is provided so as to be slightly larger than a radius of the bottom surface  23   a  of the lower flange portion  23  of the drum core  20 . In the present embodiment, the recessed portion  58  is placed at a center area of the drum mounting portion  52 . Then, the locating protrusion  23   b  of the drum core  20  fits into the recessed portion  58  for locating the drum core  20  with respect to the base  50 . 
         [0034]    In the meantime, the ring mounting portion  53  corresponds to a second mount portion. The ring mounting portion  53  is positioned at an outer circumferential side of the drum mounting portion  52 , being across the first circumference wall  57 ; and the ring mounting portion  53  is raised above the drum mounting portion  52  (i.e., positioned at a higher elevation). The ring mounting portion  53  is the part which the ring core  40  is placed. A second circumference wall  59 , which is a boundary between the ring mounting portion  53  and the outer circumference wall  54 , is provided so as to be almost circular in its overhead view in the same way as the first circumference wall  57  is. A dimension in a radial direction from the center position of the drum mounting portion  52  to the second circumference wall  59  is decided so as to be able to place a bottom surface  40   a  of the ring core  40  onto the ring mounting portion  53 . 
         [0035]    As  FIG. 2  clearly shows, the ring mounting portion  53  is provided to be an arc in a state that both ends exist (with its length limited). Each of both the ends of the ring mounting portion  53  is provided with the concave portion  55  and the protrusion  56 , to be described later. 
         [0036]    As described above, being located at each of both the ends of the ring mounting portion  53 , the concave portion  55  is provided so as to have a shape cutting out a part of the base  50  in the short hand direction of the base  50 , as shown in  FIG. 6 . In the present embodiment, the concave portion  55  is located at each of both the ends of a pair of the ring mounting portion  53 , shaped almost like a circle; accordingly there exist four concave portions  55  in total. Each concave portion  55  is a part where the coil end part  32  of the coil  30  is threaded through, as described later. 
         [0037]    The concave portion  55  shown in  FIG. 6  is provided to be shaped almost like a right triangle with its tip part rounded. Not limited to having such a shape, alternatively it is possible for the concave portions  55  to be adapted to any of other various shapes (for example, a polygonal shape such as a rectangular, or a circular form, and so on). Furthermore, the number of concave portions  55  is not limited to four, and any number of concave portions  55  may be placed as far as they are at least two concaves (the same can be said for the number of protrusions  56  as well, to be explained next). 
         [0038]    Each of the protrusions  56  is provided in such a way as to cover over each of the concave portions  55 . Protruding from an edge part of the ring mounting portion  53 , the protrusion  56  is provided so as to hang over the concave portion  55 . As shown in  FIG. 5 , the protrusion  56  is provided so as to have its bottom surface  56   a  located higher than a highest part of the terminals  51 . Furthermore, the coil end part  32  of the coil  30  is positioned at the bottom surface  56   a  of the protrusion  56 . Therefore, the protrusion  56  only may need to protrude over the concave portion  55  to a certain extent required for the coil end part  32  of the coil  30 . In the present embodiment, the protrusion  56  protrudes in such a way as to cover approximately half of the  55 , as shown in  FIG. 6 . 
       (Method of Mounting the Magnetic Element) 
       [0039]    Explained below is a way of mounting the magnetic element  10  having a structure as described above. At first, the drum core  20  is placed on the drum mounting portion  52  of the base  50 . At this time, the locating protrusion  23   b  fits into the recessed portion  58 . An adhesive may be applied to the bottom surface  23   a  of the lower flange portion  23  before the drum core  20  is placed on the drum mounting portion  52 . 
         [0040]    Then, the lead wire  31  is wound on the bobbin  24  of the drum core  20 , by making use of a wire-winding machine, or by hand work. Through the winding operation, the primary coil  30 A and the secondary coil  30 B are formed. Coil end part  32  of the primary coil  30 A and the secondary coil  30 B are left in a condition of being led out, after the winding operation. 
         [0041]    Then, a coil end part  32  of the coil  30  is led from the bobbin  24  through the clearance portion  44  in an obliquely downward direction so that the coil end part  32  is eventually led outside the ring core  40 . In the meantime, the coil end part  32  is placed at the concave portion  55 , and also placed at the bottom surface  56   a  of the protrusion  56 . Thus, the coil end part  32  of the coil  30  reaches a terminal  51 , and the coil end part  32  is wound on the terminal  51 . Then, as shown in  FIG. 7 , the coil end part  32  of the lead wire  31  makes contact with the protrusion  56 , and becomes curved there to form a bend P at the position. Furthermore, after winding the coil end part  32  on the terminal  51 , the coil end part  32  and the terminal  51  may be fixed and stabilized through soldering while both the components being under a electrically-conducted condition. 
         [0042]    Then, while the cutout portion  43  of the ring core  40  being oriented in a direction toward a side where the terminals  51  are lined up, the ring core  40  is placed on the ring mounting portion  53 . Here, the bend P is formed in the coil end part  32  owing to presence of the protrusion  56 , and at the same time the coil end part  32  is placed into the concave portion  55 , as shown in  FIG. 7 . Therefore, a part of the lead wire  31  positioned to be closer toward the coil  30  than the bend P approaches a center side of the drum core  20  more (Refer to a solid-lined lead wire  31  and a double-dashed chain-lined lead wire  31  in  FIG. 7 ). Thus, this prevents the ring core  40  and the lead wire  31  from interfering with each other. At the time of placement of the ring core  40 , an adhesive may be applied to the bottom surface  40   a  of the ring core  40 . 
       Effect of the Invention 
       [0043]    In the magnetic element  10  having a structure as described above, the coil end part  32  of the coil  30  is placed at the concave portion  55 , and then placed at the bottom surface  56   a  of the protrusion  56 . Therefore, the coil end part  32  does not cross over the ring mounting portion  53 . As a result, this makes it possible to keep the coil end part  32  of the coil  30  from becoming an obstacle at the time of placing the ring core  40  onto the ring mounting portion  53 . 
         [0044]    In other words, it is possible to prevent the coil end part  32  of the coil  30  from being pinched between the ring core  40  and the ring mounting portion  53  and therefore this makes it possible to prevent the ring core  40  from becoming tilted, unstable, and so on. As a result, the ring core can precisely be positioned. Furthermore, since it is possible to prevent the coil end part  32  from being positioned on the ring mounting portion  53 , installation of the ring core  40  onto the ring mounting portion  53  can be carried out easily, and therefore an increase in working man-hours can be suppressed. 
         [0045]    Moreover, in the present invention, the coil end part  32  of the coil  30  is placed into the concave portion  55 . Therefore, in comparison with a case where the concave portion  55  is not provided, the bend P of the coil end part  32  can be so positioned as to be closer toward the center side of the drum core  20  in a radial direction. Accordingly, the part of the lead wire  31  positioned to be closer toward the coil  30  than the bend P approaches the center side of the drum core  20  more. Thus, this makes it possible to prevent the ring core  40  and the lead wire  31  from interfering with each other, and eventually it becomes possible effectively to preclude the ring core  40  and the lead wire  31  from interfering with each other (i.e., the coil end part  32  becomes an obstacle for placement of the ring core  40 ). 
         [0046]    Furthermore, in the present invention, the drum core  20  includes the locating protrusion  23   b  protruding in a direction to a side of the base  50 , while the base  50  includes the recessed portion  58  into which the locating protrusion  23   b  fits. Therefore, as the locating protrusion  23   b  fits into the recessed portion  58 , the drum core  20  is precisely positioned with respect to the base  50 . As a result, the magnetic element  10  is able to have stable characteristics. 
         [0047]    Moreover, in the present invention, the clearance portion  44  is formed in the ring core  40 . Accordingly, the coil end part  32  of the coil  30  can be easily led into the concave portion  55  through the clearance portion  44  from the bobbin  24 . Therefore, the coil end part  32  of the coil  30  can easily be wound on the terminal  51  in a state of being positioned with the protrusion  56  at the concave portion  55 . 
       Modifications 
       [0048]    Explained above is the magnetic element  10  according to the embodiment of the present invention; and besides the embodiment, various other modifications may be made in relation to the present invention, as described below. 
         [0049]    In the embodiment described above, the drum core  20  is used as the first core member, while the ring core  40  is used as the second core member. However, the first core member is not limited to the drum core  20 , and neither is the second core member limited to the ring core  40 . For example, a T-shaped core may be used as the first core member, while a pot-shaped core may be used as the second core member. 
         [0050]    Moreover, in the embodiment described above, the upper flange portion  21  and the lower flange portion  23  of the drum core  20  have their diameters that are almost the same. However, for example, the upper flange portion may be so formed as to have a larger diameter than the lower flange portion has; and contrarily the upper flange portion may be so formed as to have a smaller diameter than the lower flange portion has. Furthermore, a drum type core may be formed by combining a T-shaped core with a disc-shaped core, in place of the drum core. 
         [0051]    Moreover, in the embodiment, the drum core  20  and the ring core  40  are provided to be circular in their overhead views. However, shapes of the drum core and the ring core are not limited to circular shapes in their overhead views, and these core components may be formed in various other shapes including polygonal shapes, such as a box shape, a hexagonal shape, an octagonal shape, and the like as well as an oval shape and so on. 
         [0052]    Furthermore, in the embodiment, the ring mounting portion  53  is formed to be flat. However, applied may be another structure, in which the ring mounting portion  53  includes a protrusion protruding upward, while a groove or the like, into which the protrusion fits, is formed at the bottom surface of the ring core  40  so that the ring core  40  is positioned with respect to the base  50  by fitting the protrusion into the groove or the like. 
         [0053]    Moreover, in the embodiment described above, the explanation is made about a transformer as the magnetic element to which the present invention is applied. However, the magnetic element is not limited to such a transformer, and the present invention may be applied to any magnetic element other than a transformer (an inductor, a choke coil, a filter, and so on). 
         [0054]    Furthermore, an application of the magnetic element  10  of the embodiment described above is not limited to any specific purpose, and the magnetic element can be used for various applications. 
       INDUSTRIAL APPLICABILITY 
       [0055]    The magnetic element according to the present invention can be applied in fields of electric appliances. 
       REFERENCE NUMERALS 
       [0000]    
       
           10 . Magnetic element 
           20 . Drum core (corresponding to the first core member) 
           21 . Upper flange portion 
           22 . Column portion 
           23 . Lower flange portion 
           23   b . Locating protrusion 
           30 . Coil 
           31 . Lead wire 
           32 . Coil end part 
           40 . Ring core (corresponding to the second core member) 
           41 . Open portion 
           42 . Core part 
           44 . Clearance portion 
           50 . Base 
           51 . Terminal 
           52 . Drum mounting portion (corresponding to the first mount portion) 
           53 . Ring mounting portion (corresponding to the second mount portion) 
           54 . Outer circumference wall 
           55 . Concave portion 
           56 . Protrusion 
           58 . Recessed portion