Abstract:
An inductive element having a gap and a fabrication method thereof are disclosed. The fabrication method is for fabricating an inductive element having a first core body, a second core body and a gap, and includes: coating an adhesive on a gap-facing side of the first core body and/or the second core body; providing a linear spacer and installing the linear spacer between the first core body and the second core body; and combining the side of the first core body where the adhesive is coated with the side of the second core body where the adhesive is coated, allowing the linear spacer to form the gap when the first core body is combined with the second core body. Thereby, the linear spacer establishes the size of the gap of the inductive element and improves the adhesion of the first core body to the second core body.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    This invention relates to an inductive element having a gap and a fabrication method thereof, and more particularly, to an inductive element that uses a linear spacer to control the size of the gap and a fabrication method thereof. 
         [0003]    2. Description of Related Art 
         [0004]    An inductive element is a passive element in an electronic circuit. An inductive element typically comprises a magnetic core and a coil. In electronic circuits, inductive element come in a variety of types depending on the desired attributes. One type of inductive element is an inductive element having a gap. Compared to an inductive element without a gap, an inductive element having a gap has a coil that is installed on a ferrite element to thereby provide lower inductance and greater current. The gap prevents the inductive element from entering the saturation state and becoming useless when current flows through the inductive element. 
         [0005]    For a general inductive element having a gap, the larger the gap, the smaller the inductance of the inductive element becomes, and vice versa. Therefore, the inductive element may be manufactured to the desired inductance by controlling the size of the gap. 
         [0006]      FIG. 1  is a perspective diagram of an inductive element  1  having a low inductance and high current-carrying capability according to the prior art. The inductive element  1  comprises an upper core body  11 , a tape  12 , an adhesive  14 , a lower core body  15  and a coil  16 . In fabrication, the adhesive  14  is covered on the lower core body  15 , tape  12 , which can endure high temperatures, is stuck to the upper core body  11 , and then the upper core body  11  that is affixed with the tape  12  covers the lower core body  15  covered with the adhesive  14 . The upper core body  11  is spaced apart from the lower core body  15  by the tape  12  of a predetermined thickness to form a gap, and is adhered to the lower core body  15  by the adhesive  14 . In order for the upper core body  11  to be at a uniform distance from the lower core body  15  (i.e., the size of the gap), the tape  12  is fabricated to have a large surface area, and is applied to the contact surface between the upper core body  11  and the lower core body  15 . 
         [0007]    Therefore, such an inductive element  1  uses the tape  12  to establish the size of the gap, and the thicker the tape  12 , the lower the inductance of the inductive element  1  becomes. 
         [0008]    However, the inductive element of the prior art has the following drawbacks. 
         [0009]    (1) The tape has too large an area in contact with the core bodies. As shown in  FIG. 1 , the large area occupied by the tape  12 , which is used in order for the gap to have a uniform size, covers a significant portion of the side of the upper core body  11  that contacts the adhesive  14 , such that the adhesive  14  cannot maximally adhere the upper core body  11  to the lower core body  15 , leaving the upper core body  11  easily detachable from the lower core body  15 . 
         [0010]    (2) Use of the tape has low accuracy. As formerly stated, the inductance of the inductive element is affected by the gap size, and the gap of the inductive element has to have a uniform size. However, the tape used in the prior art has too large a tolerance (that is, the difference in the thickness of the tape at various places), so the inductive element does not have a uniform inductance. 
         [0011]    (3) The inductive element of the prior art incurs high costs. There is a limited number of types of high-temperature endurable tapes in the market, so most users order their own dedicated tapes, which costs a lot of money, and the inductive element that uses such tapes have a correspondingly higher cost. 
         [0012]    In conclusion, finding a way to provide an inductive element that can more accurately, securely and cheaply form the gap, and do so in a way that can tolerate the high temperatures encountered in manufacture or application, is an important goal in the art. 
       SUMMARY OF THE INVENTION 
       [0013]    In view of the above-mentioned problems of the prior art, the present invention provides a fabrication method for fabricating an inductive element having a gap. The fabrication method is for fabricating an inductive element having a first core body, a second core body and the gap, and includes the steps of: (1) coating an adhesive on a gap-facing side of the first core body and/or the second core body; (2) providing a linear spacer and installing the linear spacer between the first core body and the second core body; and (3) combining the side of the first core body where the adhesive is coated with the side of the second core body where the adhesive is coated, allowing the linear spacer to form the gap when the first core body is combined with the second core body. 
         [0014]    In an embodiment of the present invention, the fabrication method further includes the step (4) providing at least two elastic elements and installing the elastic elements on two opposite sides of the inductive element, respectively, for fixing in position the first core body, the linear spacer and the second core body adhering to one another. 
         [0015]    In another embodiment of the present invention, the step (4) further includes baking the inductive element fixed in position by the elastic elements, cooling the inductive element after the inductive element is baked, and removing the elastic elements after the inductive element is cooled. 
         [0016]    The present invention further provides an inductive element having a gap. In an embodiment of the present invention, the inductive element includes a first core body; a second core body; and at least a linear spacer installed between first core body and the second core body for forming the gap when the first core body is combined with the second core body. 
         [0017]    In an embodiment of the present invention, the inductive element further includes an adhesive coated on the first core body and/or the second core body for being filled into the gap when the first core body is combined with second core body, such that the first core body is adhered to the second core body. 
         [0018]    In another embodiment of the present invention, the linear spacer is made of a metal that can endure a temperature as high as 125 degrees Celsius, and has its cross section all along its length have the same area. 
         [0019]    In yet another embodiment of the present invention, the first core body and/or the second core body is in the shape of the letter “E”, “I” or “H”. 
         [0020]    Therefore, in an inductive element having a gap and a fabrication method thereof according to the present invention, since the linear spacer, which is used for forming the gap, has a low cost, a small area of contact with the core bodies, and high accuracy, the drawbacks of the prior art are thus overcome. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0021]      FIG. 1  is a perspective diagram of an inductive element that takes a planar tape as a spacer according to the prior art; 
           [0022]      FIG. 2  is a flow chart of a fabrication method for an inductive element having a gap according to the present invention; 
           [0023]      FIG. 3A  is a perspective diagram of an “E”-shaped inductive element having a gap according to an embodiment to the present invention; 
           [0024]      FIG. 3B  is a side view of the inductive element shown in  FIG. 3A ; 
           [0025]      FIG. 4  is a perspective diagram of an “E”-shaped inductive element having a gap according to another embodiment the present invention; 
           [0026]      FIG. 5  is a perspective diagram of an “H”-shaped inductive element having a gap according to the present invention; and 
           [0027]      FIG. 6  is a perspective diagram of an “I”-shaped inductive element having a gap according to the present invention. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0028]    The following illustrative embodiments are provided to illustrate the disclosure of the present invention, these and other advantages and effects being readily understandable by those in the art after reading the disclosure of this specification. The present invention can also be performed or applied by other embodiments. The details of the specification may be on the basis of specific viewpoints and applications, and numerous modifications and variations can be devised without departing from the spirit of the present invention. 
         [0029]      FIG. 2  is a flow chart of a fabrication method for an inductive element having a gap according to an embodiment of the present invention. Note that only the steps that relate to the present invention are shown in  FIG. 2 , further steps hereby being omitted for clarity. 
         [0030]    As shown in  FIG. 2 , the fabrication method for an inductive element having a gap according to the present invention includes the following steps. 
         [0031]    In step S 601 , an adhesive is coated on a gap-facing side of a first core body and/or a second core body. The adhesive is a thermosetting adhesive, thermoplastic adhesive, silicone adhesive or epoxy adhesive. In the embodiment, the adhesive is for adhering the first core body to the second core body. The present invention neither limits the amount of the adhesive used nor limits the first or second core body coated with the adhesive. Next, proceed to step S 602 . 
         [0032]    In step S 602 , at least a linear spacer is provided and is installed between the first core body and the second core body. In an embodiment of the present invention, the linear spacer has its cross section all along its length to have the same area, and has a round cross section perpendicular to the direction in which it extends. In other words, the linear spacer has a slim linear body that has a uniform radius from an initial end to a terminal end, and can be easily fabricated in various sizes. The linear spacer is made of a metal capable of enduring a temperature as high as 135±10 degrees Celsius. Preferably, the linear spacer is a copper wire. In the embodiment, at least a linear spacer is installed between the first core body and the second core body. Preferably, two linear spacers are installed between the first core body and the second core body. Next, proceed to step S 603 . 
         [0033]    In step S 603 , the side of the first core body where the adhesive is coated is correspondingly combined with the side of the second core body where the adhesive is coated on. The word “correspondingly” herein means that the first core body and the second core body correspond in shape to each other when combined. For example, if both the first core body and the second core body are in the shape of the letter “E”, the first core body and the second core body are combined in a mouth-to-mouth manner. The linear spacer allows a gap to be formed between the first core body and the second core body when the first core body is combined correspondingly with the second core body. Next, proceed to step S 604 . 
         [0034]    In step S 604 , at least two elastic elements such as clamps are provided and installed on two opposite sides of the first core body and the second core body, to fix in position the first core body, the linear spacer and the second core body adhering to one another. Therefore, the first core body, the linear spacer and the second core body are clamped by the forces applied by the clamps in the direction perpendicular to the gap. Next, proceed to step S 605 . 
         [0035]    In step S 605 , the first core body, the linear spacer and the second core body that are adhered by the two clamps (the elastic elements) are baked in an oven at a temperature of 135±10 degrees Celsius for 30 minutes. Next, proceed to step S 606 . 
         [0036]    In step S 606 , after the first core body, the linear spacer and the second core body have been removed from the baking equipment, the first core body, the linear spacer and the second core body that are adhered by the two clamps (elastic elements) are cooled for 30 minutes and then the elastic elements are removed, thus completing the fabrication process of the inductive element having the gap. 
         [0037]    The above embodiments of the present invention disclose an inductive element that is fabricated by the fabrication method for an inductive element having a gap, wherein a first core body and a second core body that are adhered to each other firmly form a gap using a linear spacer that has a small surface area in contact with the cores. Moreover, since the linear spacer has its cross section all along its length to have the same area, the gap formed by the linear spacer has an accurate size. Further, since the linear spacer of the invention is easily fabricated to any size and has a low fabrication cost, an inductive element that includes the linear spacer can have a lower fabrication cost. 
         [0038]      FIG. 3A  is a perspective diagram of an “E”-shaped inductive element  2  having a gap  25  according to the present invention. The inductive element  2  comprises a first core body  21 , a second core body  22 , a linear spacer  23  (which may be split) and a coil  24 . 
         [0039]    The first core body  21  and the second core body  22  are made of a magnetic material and, preferably, are each a ferrite core or a magnetic core. As shown in  FIG. 3A , both the first core body  21  and the second core body  22  are in the shape of the letter “E”. The coil  24  of the inductive element  2  is installed in an intermediate portion  222  of the center member of the “E”-shaped second core body  22 . In another embodiment of the present invention, the coil  24  encircles an intermediate portion  212  of the “E”-shaped first core body  21  and the intermediate portion  222  of the “E”-shaped second core body  22 . 
         [0040]    Referring to  FIG. 3B , which is a side view of the inductive element  2  shown in  FIG. 3A , the linear spacer  23  is installed between the first core body  21  and the second core body  22 . Since the linear spacer  23  occupies a substantive space, the installation of the linear spacer  23  leads to the formation of a gap  25  between the first core body  21  and the second core body  22  when the first core body  21  is combined with the second core body  22 . In an embodiment of the present invention, the linear spacer  23  has its cross section all along its length maintain the same area. In other words, the linear spacers  23  has the same thickness (diameter/thickness/height) from an initial end to a terminal end. In the embodiment shown in  FIGS. 3A and 3B , the linear spacer  23  has a round cross section that is perpendicular to the direction in which the linear spacer  23  extends. In other words, the linear spacer  23  has a slim linear body. Such a design allows the opposite sides of the first core body  21  and the second core body  22  to be parallel when the first core body  21  is combined with the second core body  22 , and reduces the contact area between the linear spacer  23  and the first and second core bodies  21 ,  22 . 
         [0041]    Since the inductive element is baked at a temperature of 135±10 degrees Celsius, the linear spacer  23  is made of a metal capable of enduring a temperature as high as 125 degrees Celsius. In an embodiment of the present invention, the linear spacer  23  is made of copper. Preferably, the linear spacer  23  is a copper wire. 
         [0042]    Note that since the linear spacer  23  is used for establishing a space between the first core body  21  and the second core body  22  to form the gap  25  when the first core body  21  is combined with the second core body  22 ; however, the amount and arrangement of the linear spacer  23  are not limited to the embodiment shown in  FIGS. 3A and 3B . 
         [0043]    The inductive element  2  further comprises an adhesive (not shown). During the fabrication of the inductive element  2 , the adhesive is coated on a first portion  211  and a second portion  213  of the “E”-shaped first core body  21  and on a first portion  221  and a second portion  223  of the “E”-shaped second core body  22  after the coil  24  is installed in the intermediate portion  222  of the “E”-shaped second core body  22 . Then, the linear spacer  23  is installed on a side of the second core body  22  where the adhesive is coated, such that the linear spacer  23  is installed across the first portion  211  and the second portion  213  of the first core body  21 . The first core body  21  is then combined with the second core body  22 , such that the first core body  21  and the second core body  22  are adhered to each other when the first core body  21 , which is spaced apart from the second core body  22  by the linear spacer  23 , is combined with the second core body  22 . 
         [0044]    It can be discerned from the above embodiments that the linear spacer  23  is for establishing a space between the first core body  21  and the second core body  22  to form the gap  25  when the first core body  21  is combined with the second core body  22 . Since the linear spacer  23  is made of metal and metal has good ductility, the linear spacer  23  can be fabricated to have a uniform size from the head to the tail, and can be cut into a plurality of segments of the same radius. Therefore, during the fabrication of the inductive element  2  shown in  FIGS. 3A and 3B , a plurality of inductive elements having gaps of the same size can be obtained, since the linear spacer  23  has a highly accurate size. Given the small contact area between the linear spacer  23  and the first and second core bodies  21 ,  22 , the adhesive covers relatively large areas of the first core body  21  and the second core body  22  of the inductive element  2  according to the present invention, as compared with the inductive element of the prior art. Accordingly, the adhesion between the first core body  21  and the second core body  22  is greatly improved. 
         [0045]    The linear spacer, which is made of a copper wire, for example, is easily fabricated to any size (radius) with high accuracy and low costs. In general, the copper wire is a conductive material and is used as a coil of the inductive element. In an embodiment of the present invention, the copper wire is used as the linear spacer of the present invention, for leaving a space between the first core body and the second core body to form the gap. Accordingly, the inductive element having the linear spacer (e.g., the copper wire) has a low cost. 
         [0046]    Compared with the inductive element of the prior art, which uses planer tape as the spacer, the inductive element of the present invention, which uses the copper wire as the linear spacer, has a low cost, high gap accuracy, and good adhesion between the first core body and the second core body. 
         [0047]    Referring to  FIGS. 4-6 , there are shown perspective diagrams of an inductive element having a gap of various embodiments according to the present invention. The inductive elements shown in  FIGS. 4-6  has the same basic components as the inductive element shown in  FIGS. 3A and 3B , so only the differences between the inductive elements are described in the following paragraphs. 
         [0048]    As shown in  FIG. 4 , which is a perspective diagram of an inductive element  3  having a gap of another embodiment according to the present invention, the inductive element  3  comprises a first core body  31 , a second core body  32 , a linear spacer  33 , a coil  34  and an adhesive (not shown). The first core body  31  is rectangular, while the second core body  32  is in the shape of the letter “E”. The coil  34  of the inductive element  3  is installed at an intermediate portion  322  of the “E”-shaped second core body  32 . The adhesive is coated on a first end portion  321  and a second end portion  323  of the second core body  32 . The linear spacer  33  is installed between the first core body  31  and the second core body  32  and installed across the first end portion  321  and the second end portion  323  of the second core body  32 , to form a gap when the first core body  31  is combined with the second core body  32 , allowing the first core body  31 , the linear spacer  33  and the second core body  32  to be adhered to one another. 
         [0049]      FIG. 5  is an inductive element  4  having a gap of yet another embodiment according to the present invention. A first core body  41  is rectangular, and a second core body  42  is in the shape of the letter “H”. A coil  44  of the inductive element  4  is installed in an intermediate portion  422  of the “H”-shaped second core body  42 . An adhesive (not shown) is coated on a first portion  421  and a second portion  423  of the second core body  42 . A linear spacer  43  is installed across the first portion  421  and the second portion  423  of the second core body  42 . Alternatively, the linear spacer  43  is installed on the first portion  421  and the second portion  423  of the second core body  42 , respectively. 
         [0050]      FIG. 6  is an inductive element  5  having a gap of yet another embodiment according to the present invention. A first core body  51  is rectangular, and a second core body  52  is in the shape of the letter “I”. A coil  54  of the inductive element  5  is installed at an intermediate portion  522  of the “I”-shaped second core body  52 . An adhesive (not shown) is coated on the first end portion  521  and the second end portion  523  of the second core body  52 . A linear spacer  53  is installed across the first portion  521  and the second portion  523  of the second core body  52 . Alternatively, the linear spacer  53  is installed on the first end portion  521  and the second end portion  523  of the second core body  52 , respectively. 
         [0051]      FIGS. 4-6  differ only in the shape of the core bodies of the inductive element (“E”-shaped, “H”-shaped or “I”-shaped). As was the case with the first embodiment, a linear spacer controls the size of the gap of the inductive element, and the installation of the linear spacer between the first core body and the second core body forms the gap when the first core body is combined with the second core body. 
         [0052]    In conclusion, an inductive element having a gap according to the present invention has the following advantages: 
         [0053]    (1) The contact area between the linear spacer and the core bodies is small, allowing the first core body to be firmly adhered to the second core body. Since the adhesive is coated on the gap-facing side of the first core body and/or the second core body, and the linear spacer is installed between the first core body and the second core body, the small contact area between the linear spacer and the core bodies allows the first core body and the second core body to have a large adhesion area, and thus improves the adhesion between the first core body and the second core body. 
         [0054]    (2) The linear spacer has a constant thickness, such that the size of the gap of the inductive element created by the linear spacer is accurately established with little variance. Since the linear spacer has its cross section all along its length have the same area and be perpendicular to the direction in which it is extended, the segments formed by cutting the linear spacer in a direction perpendicular to the extension direction also have the same size (that is, the tolerance between the segments is small). Thus, the gap formed by the installation of the linear spacer between the first core body and the second core body when the first core body is combined with the second core body has an accurate size. The linear spacer not only controls the size of the gap of the inductive element, it also ensures the uniformity of the size of the gap of the inductive element. 
         [0055]    (3) The linear spacer incurs low costs. Accordingly, an inductive element that is fabricated with the linear spacer can have a lower cost than what might otherwise be possible. Since the linear spacer is easily fabricated to have a desired size, and there are many linear spacers of various sizes in the market, an inductive element that is fabricated with a linear spacer of a predetermined size can be manufactured at a reduced cost. The foregoing descriptions of the detailed embodiments are provided to illustrate and disclose the features and functions of the present invention and are not intended to be restrictive of the scope of the present invention. It should be understood by those in the art that many modifications and variations can be made according to the spirit and principle in the disclosure of the present invention and still fall within the scope of the invention as set forth in the appended claims.