Abstract:
A magnetic component having a magnetic core structure includes a core body with a notched region for reducing non-essential core material. The notched region has the cross-sectional shape of a trapezoid and includes two notch walls separated by a middle wall. The notch walls are each oriented at an obtuse angle relative to the middle notch wall. The core structure reduces the cost of manufacture and the size of the magnetic component by eliminating non-essential core material from regions of the core that have little or no impact on the magnetic performance of the component. The desired magnetic flux path in the component remains substantially unaffected by the removal of the non-essential core material. The body of the core may also include one or more angled shoulders positioned at the corners of the core body to further eliminate non-essential core material.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     This application is a Non-Provisional Utility application which claims the benefit of co-pending U.S. Provisional Patent Application Ser. No. 61/168,877 filed Apr. 13, 2009 entitled “LOW COST FERRITE “E” CORE STRUCTURE” which is hereby incorporated by reference in its entirety. 
    
    
     A portion of the disclosure of this patent document contains material that is subject to copyright protection. The copyright owner has no objection to the reproduction of the patent document or the patent disclosure, as it appears in the U.S. Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever. 
     BACKGROUND OF THE INVENTION 
     The present invention relates generally to a magnetic component having a core structure for guiding and concentrating a magnetic field and specifically to a magnetic core structure designed for achieving a desired magnetic flux pattern using a minimized amount of core material to reduce size and manufacturing cost. 
     More particularly, this invention pertains to magnetic components having ferrite cores for guiding and concentrating magnetic fields. Such components are found in many consumer and industrial electronic devices and are an important part of the electronics industry. Magnetic components of this type, such as transformers and inductors, generally include one or more coils of conductive wire wound around a ferrite core. As current passes through the coil, a magnetic field is generated around the wire. The magnetic field is then concentrated and strengthened by the ferrite core as magnetic flux passes through the core. The shape and design of the core greatly influences the magnetic and electronic performance of the component. 
     A common core design includes three rectangular solid legs extending from a rectangular solid body, forming the shape of an “E”. Traditional E cores are used in known electrical components. In a basic transformer, for example, the traditional E core is generally positioned with the legs abutting a separate ferrite structure, commonly a rectangular ferrite solid or a separate E core, to form a magnetic flux path through the legs and body of the core and the separate structure. A conductive coil is positioned around the middle leg of the core. The traditional configuration allows magnetic flux to pass through the legs of the core in a closed loop when current is passed through the conductor. Traditional E cores are usually made of ferrite, but may include additional materials. 
     The traditional E core design is widely used because its simple design makes it easy to manufacture at relatively low cost. Additionally, the design of the traditional E core yields reliable performance because the magnetic flux path follows a uniform route through the legs and body of the core. Yet, despite its design simplicity and convenience for low-cost manufacture, the traditional E core includes non-essential core material in core regions where little or no magnetic flux is present. Non-essential core regions have a negligible effect on the magnetic performance of the core because such regions do not constitute part of the magnetic flux path. The inclusion of non-essential core material in traditional E cores needlessly raises both the cost of manufacture and the overall size of magnetic components. 
     Others have attempted to produce magnetic components having modified core designs that remove non-essential core material. These attempts include notches on the core body having circular, rectangular or triangular profiles or angled corners. Previous attempts have produced cores that include complex and three-dimensional curvilinear geometries. While more complex curvilinear cores, including pot cores, offer benefits of reduced non-essential core material and desired core performance, they require more expensive and time consuming design and manufacturing processes. The additional cost and geometrical complexity of prior art cores renders them unsuitable for use as a low cost alternative to the traditional E core design. 
     Accordingly, there is a need in the art for providing a magnetic component having a magnetic core structure that reduces both overall component size and manufacturing cost by eliminating non-essential core material while maintaining desirable magnetic and electrical performance characteristics. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention provides a magnetic component for an electronic circuit that includes a magnetic core structure for guiding a magnetic field, the core structure requiring a reduced amount of material while maintaining desired performance characteristics. The magnetic core structure includes a core body and three legs extending from the core body. The core body includes a notched recess generally having the cross-sectional profile of a trapezoid. The notched recess eliminates non-essential core material that has little or no effect on the magnetic performance of the core. The notched recess includes a first notch wall, a second notch wall and middle notch wall. The first and second notch walls are each oriented at an obtuse angle relative to the middle notch wall. The core body may additionally include one or more chamfered shoulders positioned on the core body to further remove non-essential core material. 
     It is therefore a general object of the present invention to provide a magnetic component including a core structure having non-essential core material removed. 
     Another object of the present invention is to provide a magnetic component including a core structure having a design that reduces the cost of core manufacture by using less core material. 
     Yet another object of the present invention is to provide a magnetic component including a core structure that maintains desired magnetic and electronic performance by providing a sufficient magnetic flux path while eliminating unnecessary core material. 
     Still yet another object of the present invention is to provide a magnetic component including a core structure having reduced volume that can accommodate the same amount of magnetic flux as a core having a larger volume. 
     A further object of the present invention is to provide a magnetic component including a core structure designed for reducing the amount of core material while maintaining a desired cross-sectional profile in the magnetic flux path. 
     Still yet another object of the present invention is to provide a magnetic component including a core structure with a uniform flux path. 
     Another object of the present invention is to provide a magnetic component including a core structure that can be used for multiple applications. 
     Numerous other objects, features and advantages of the present invention will be readily apparent to those skilled in the art, upon a reading of the following disclosure, when taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         FIG. 1  is a top view of a magnetic core structure consistent with the present invention. 
         FIG. 2  is an end view of the magnetic core structure of  FIG. 1 . 
         FIG. 3  is a side view of the magnetic core structure of  FIG. 1 . 
         FIG. 4  is an end view of the magnetic core structure of  FIG. 1 . 
         FIG. 5  is a bottom view of the magnetic core structure of  FIG. 1 . 
         FIG. 6  is a side view of the magnetic core structure of  FIG. 1 . 
         FIG. 7  is a perspective view of the magnetic core structure of  FIG. 1 . 
         FIG. 8  is a perspective view of a magnetic core structure consistent with the present invention. 
         FIG. 9  is a perspective view of the magnetic core structure of  FIG. 8 . 
         FIG. 10  is a plan view of the magnetic core structure of  FIG. 9 . 
         FIG. 11A  is a plan view of a magnetic component including a prior art magnetic core structure 
         FIG. 11B  is a plan view of a magnetic component including a magnetic core structure consistent with the present invention. 
         FIG. 12  is an exploded view of a magnetic component consistent with the present invention. 
         FIG. 13  is perspective view of a magnetic component consistent with the present invention. 
         FIG. 14 . is a perspective view of a core structure consistent with the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the drawings,  FIGS. 1-7  illustrate several views of one embodiment of a core structure for a magnetic component consistent with the present invention. One embodiment includes a core structure  10  having a core body  14 , a first leg  44  having a top surface  46 , a second leg  54  having a top surface  56  and a center winding leg  64  having a top surface  66 . The core body  14  includes a first side surface  16 , a second side surface  18 , a top surface  28 , a bottom surface  30 , a first end surface  20  and a second end surface  22 . The core  10  may be formed in a variety of ways, including molding, casting, extruding, cutting or sintering. In one embodiment, the core  10  is made of a ferrite. In other embodiments the core  10  can be made of other material or combinations of materials having magnetic permeability. 
     Referring to  FIG. 7 , in one embodiment, the first side surface  16  may be divided into a first side surface primary region  24  and a first side surface secondary region  26  by a notched recess  74 . The notched recess  74  includes a first notch wall  76 , a second notch wall  78  and a middle notch wall  80 . Each notch wall extends from the top surface  28  of the core body  14  to the bottom surface  30  of the core body  14 . The notched recess  74  eliminates non-essential material from the core body  14  while maintaining sufficient core material in the core body  14  to accommodate a desired amount of magnetic flux. Non-essential core material is defined as material in the core body  14 , first leg  44 , second leg  54  or center winding leg  64  that is not part of the desired magnetic flux path for a component operating condition. In one embodiment, the notched recess  74  may be positioned on the core body  14  opposite the center winding leg  64 . In alternative embodiments, the notched recess  74  may be positioned elsewhere on the first side surface  16  of the core body  14 . 
     Referring now to  FIG. 8  and  FIG. 9 , one embodiment of a magnetic core structure  10  embodying the principles of the present invention is shown. The core body  14  may include a first shoulder  32 . The first shoulder defines a first shoulder surface  34  positioned between the first end surface  20  and the first side surface  16  of the core body  14 . Further consistent with the present invention, a second shoulder  38 , defining a second shoulder surface  40  may be positioned on the core body  14  between the first side surface  16  and the second end surface  22 . The first shoulder  32  and the second shoulder  38  allow further removal of non-essential core material. 
     Referring again to  FIG. 8  and  FIG. 9 , the core body  14  may include a plurality of legs extending from the second side surface  18  of the core body  14 . The first leg  44 , center winding leg  64  or second leg  54  may share one or more surfaces with the core body  14 . In one embodiment, shown in  FIG. 8 , the top surface  46  of the first leg  44  extends coextensively with the top surface  28  of the core body  14 . As shown in  FIG. 9 , the end surface  50  of the first leg  44  coextends with the first end surface  20  of the core body  14 , and the bottom surface  48  of the first leg  44  coextends with the bottom surface  30  of the core body  14 . Referring back to  FIG. 8 , the second leg  54  shares a top surface  56  with the top surface  28  of the core body  14  and an end surface  60  with the second end surface  22  of the core body  14 . As shown in  FIG. 9 , the bottom surface  58  of the second leg  54  coextends with the bottom surface  30  of the core body  14 . Referring back to  FIG. 8 , the center winding leg shares a top surface  66  with the top surface  28  of the core body  14  and, as shown in  FIG. 9 , a bottom surface  68  with the bottom surface  30  of the core body  14 . 
     Referring now to  FIG. 10 , the first shoulder  32  is oriented at an angle W and the second shoulder  38  is oriented at an angle X. Angle W is defined as the angle between the first shoulder  32  and the first side surface primary region  24 . Angle X is defined as the angle between the second shoulder  38  and the first side surface secondary region  26 . Angles W and X are less than 90 degrees. In one embodiment, angles W and X may range between 30 and 60 degrees. In another embodiment, angles W and X are substantially equal. 
     Referring further to  FIG. 10 , the first wall  76  of the notched recess  74  is oriented at angle Y, and the second notch wall  78  is oriented at angle Z. Angle Y is defined as the angle between the first notch wall  76  and the middle notch wall  80 . Angle Z is defined as the angle between the second notch wall  78  and the middle notch wall  80 . Angles Y and Z may range between 91 and 179 degrees, and in one embodiment may be between 120 and 150 degrees. In one embodiment, angle Y is substantially similar to angle Z. In other embodiments, angle Y may be smaller or larger than angle Z. 
     Referring now to  FIG. 11A , a prior art magnetic component including a traditional E core is shown in a known configuration, wherein a first E core  106  is positioned adjacent to a second E core  108 . In the presence of a magnetic field generated by the flow of current through a nearby conductor, magnetic flux  98  travels in a closed loop through the first E core  106  and the second E core  108 . Referring now to  FIG. 11B , an embodiment of a magnetic component consistent with the present invention is shown. A first core  10  having a notched recess  74 , a first shoulder  32  and a second shoulder  38  is positioned adjacent to a second core  112  also having a notched recess  128 . The second core  112  includes a first leg  122 , a second leg  124  and a center winding leg  126 . As shown in  FIG. 11B , the magnetic flux pattern  100  is minimally affected by the presence of the notched regions  74 , 128 , the first shoulder  32  or the second shoulder  34  when compared to the magnetic flux pattern  98  of the prior art configuration shown in  FIG. 11A . 
     Referring further to  FIG. 11B , in one embodiment an air gap  118  may be present between the center winding leg  64  of the first core  10  and the center winding leg  126  of the second core  112 . Another embodiment provides uniform contact between the center winding legs  64 ,  126 . Other embodiments may include partial contact between the center leg  64  of the first core  10  and the center leg  126  of the second core  112 . 
     Referring again to  FIG. 10 , in one embodiment consistent with the present invention, the shape of the notched recess  74  is defined by the width of the middle notch wall, H, the width of the first notch wall, G, the width of the second notch wall, I, the depth of the notch, K, and the outer width of the notch, J. In one embodiment, the width, H, of the middle notch wall  80  extends at least one-half the width, B, of the center winding leg  64 . In another embodiment, the width, H, of the middle notch wall  80  is at least one-half the outer width, J, of the notched recess  74 . Consistent with the present invention, the outer width, J, of the notched recess  74  may be equal to the width, B, of the center winding leg  64 . Further consistent with the present invention, the width, H, of the middle notch wall  80  may extend at least one millimeter. In another embodiment consistent with the present invention, the notch depth K extends less than one-half the width, L, of the core body  14 . 
     Referring now to  FIG. 12 , an exploded view of a magnetic component embodying the principles of the present invention is illustrated, including a first core  10 , a second core  112  and a conductive coil  94 . The conductive coil  94  is positioned between the first core  10  and the second core  112 . The conductive coil  94  includes a passage  90  for receiving the center winding leg  64  of the first core  10  and the center winding leg  126  of the second core  112 . The embodiment allows a magnetic field generated by the conductive coil  94  to induce a magnetic flux  100  through the cores  10 ,  112 , as shown in  FIG. 11B . 
     Referring now to  FIG. 13 , one example of a magnetic component embodying the principles of the present invention, a transformer  92 , is illustrated. The transformer includes a first core  10  having a notched recess  74 , a first shoulder  32  and a second shoulder  38 . The transformer  92  also includes a conductive coil  94  and a second core  112 . The second core  112  may be formed in a variety of other shapes, including a traditional E core, a modified E core and a rectangular solid. 
     Referring now to  FIG. 14 , in an alternative embodiment further consistent with the present invention, the core body  14  includes a proximal end  101  and a distal end  105 . A first groove  102  is positioned on the proximal end  101  of the core body  14 . The first groove  102  defines the shape of a trapezoid. A second groove  103  and a third groove  104  are included on the distal end  105  of the core body  14 . The second and third grooves  103 ,  104  each define the shape of a rectangle. A first shoulder  107  and a second shoulder  109  are also positioned on the proximal end  101  of the core body  14 . The first groove  102  includes a first groove primary wall  111 , a first groove secondary wall  113  and a first groove middle wall  115 . In one embodiment, the first groove primary wall  111  is oriented at an obtuse angle relative to the first groove middle wall  115 . 
     Thus, although there have been described particular embodiments of the present invention of a new and useful Magnetic Component with a Notched Magnetic Core Structure it is not intended that such references be construed as limitations upon the scope of this invention except as set forth in the following claims.