Patent Publication Number: US-8994487-B2

Title: Transformer

Description:
TECHNICAL FIELD 
     The present disclosure relates to a transformer, and more particularly to a transformer with an increased creepage distance between a magnetic core assembly and a secondary winding coil. 
     DESCRIPTION OF THE RELATED ART 
     Magnetic elements such as inductors and transformers are widely used in power supply apparatuses or many electronic devices to generate induced magnetic fluxes. A transformer is a device that transfers electric energy from one circuit to another through coils in order to regulate the voltage to a desired range required for powering the electronic device. 
       FIG. 1  is a schematic exploded view of a conventional transformer. As shown in  FIG. 1 , the transformer  1  comprises a bobbin  10 , a primary winding coil  11 , a secondary winding coil  12 , and a magnetic core assembly  13 . The primary winding coil  11  and the secondary winding coil  12  are wound around the bobbin  10 . The outlet terminals  110  of the primary winding coil  11  and the outlet terminals  120  of the secondary winding coil  12  are wound around and fixed on pins  101 , which are extended from two opposed sides of the bobbin  10 . The magnetic core assembly  13  is combined with the bobbin  10 , and partially embedded into a channel  102  of the bobbin  10 . After the bobbin  10  and the magnetic core assembly  13  are combined together, the transformer  1  is assembled. Consequently, the transformer  1  may be electrically connected with a circuit board (not shown) through the pins  101 . 
     Moreover, after the outlet terminals  110  of the primary winding coil  11  are wound around and soldered on the pins  101  at a first side of the bobbin  10 , some drawbacks may occur. Since the gap between any two adjacent pins  101  at the first side of the bobbin  10  is very short, the region between two outlet terminals  110  of the primary winding coil  11  is possibly stained with solder paste. Under this circumstance, the transformer  1  is readily suffered from a short-circuited problem. Moreover, the creepage distance between the outlet terminals  110  of the primary winding coil  11  fixed on the pins  101  of the bobbin  10 , the creepage distance between the outlet terminals  120  of the secondary winding coil  12  fixed on the pins  101  of the bobbin  10 , the creepage distance between the outlet terminals  110  of the primary winding coil  11  and the magnetic core assembly  13  and the creepage distance between the outlet terminals  120  of the secondary winding coil  12  and the magnetic core assembly  13  are usually insufficient. Moreover, after the outlet terminals  120  of the secondary winding coil  12  are wound around and soldered on the pins  101  at a second side of the bobbin  10 , the exposed portions of the secondary winding coil  12  are usually sheathed by tubes  14 . The uses of the tubes  14  may protect the exposed portion of the secondary winding coil  12  from being cracked in response to the external force. Although the uses of the tubes  14  may protect the exposed portion of the secondary winding coil  12 , there are still some drawbacks. For example, the procedure of sheathing the tubes  14  is time-consuming and labor-intensive. In addition, the uses of the tubes  14  increase the fabricating cost. 
     As mentioned above, the outlet terminals  110  of the primary winding coil  11  and the outlet terminals  120  of the secondary winding coil  12  are respectively fixed on the pins  101  at the two opposed sides of the bobbin  10  of the conventional transformer  1 . Since the pins  101  are symmetrically arranged at the two opposed sides of the bobbin  10 , during the process of mounting the transformer  1  on a circuit board (not shown), the worker may erroneously insert the pins of the transformer  1  into unmatched conductive holes (not shown) of the circuit board. Under this circumstance, the circuit board fails to be normally operated or even the circuit board has a breakdown. In other words, the conventional transformer  1  has no foolproof mechanism for facilitate the worker to mount the transformer on the circuit board. Moreover, for fabricating the transformer  1 , the primary winding coil  11  and the secondary winding coil  12  are manually wound around the bobbin  10  and then the tubes  14  are sheathed around the secondary winding coil  12 . The process of fabricating the transformer  1  is labor-intensive and time-consuming, and the fabricating cost is high. Moreover, since the winding coils are readily broken, the process of fabricating the transformer  1  wastes much material. 
     Therefore, there is a need of providing an improved transformer in order to eliminate the above drawbacks. 
     BRIEF SUMMARY 
     The present disclosure provides a transformer. The bobbin of the transformer has plural extension structures. Each of the plural extension structures has a notch and a stepped structure. Consequently, the creepage distance between a magnetic core assembly and a secondary winding coil will be increased, and the overall volume of the transformer is reduced. 
     The present disclosure also provides a transformer whose bobbin has a stepped structure. The stepped structure comprises plural stepped parts. Due to the altitude difference between every two adjacent stepped parts, the region between every two adjacent stepped parts may be defined as a wire-managing part. The outlet terminals of the secondary winding coil may be supported on the plural stepped parts. Consequently, the creepage distance between the outlet terminals of the secondary winding coil will be increased to meet the electric safety regulations. 
     The present disclosure further provides a transformer with good electrical properties to avoid the arcing effect. Moreover, the transformer may be fabricated by an automatic winding method, and the transformer may have a foolproof positioning mechanism. 
     In accordance with an aspect of the present disclosure, there is provided a transformer. The transformer includes a bobbin, at least one primary winding coil, at least one secondary winding coil, and a magnetic core assembly. The bobbin includes a main body, plural extension structures, and plural pin groups. The main body includes a channel, plural winding sections, a first connecting seat, and a second connecting seat. The plural extension structures are connected with the first connecting seat and the second connecting seat, respectively. In addition, each of the plural extension structures has a notch and a stepped structure, and the stepped structure comprises plural stepped parts. The plural pin groups are disposed on the first connecting seat, the second connecting seat and the plural extension structures. The at least one primary winding coil and at least one secondary winding coil are wound around the plural winding sections. Each of the at least one primary winding coil and the at least one secondary winding coil includes plural outlet terminals. The magnetic core assembly is partially embedded within the channel of the main body. The plural outlet terminals of the secondary winding coil are respectively disposed on the plural stepped parts of the stepped structure and fixed on the pin group which is disposed on one of the extension structures. 
     The above contents of the present disclosure will become more readily apparent to those ordinarily skilled in the art after reviewing the following detailed description and accompanying drawings, in which: 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic exploded view of a conventional transformer; 
         FIG. 2A  is a schematic exploded view illustrating a transformer according to an embodiment of the present disclosure; 
         FIG. 2B  is a schematic assembled view illustrating the transformer of  FIG. 2A ; and 
         FIG. 3  is a schematic top view illustrating the transformer of  FIG. 2B . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The present disclosure will now be described more specifically with reference to the following embodiments. It is to be noted that the following descriptions of preferred embodiments of this disclosure are presented herein for purpose of illustration and description only. It is not intended to be exhaustive or to be limited to the precise form disclosed. 
       FIG. 2A  is a schematic exploded view illustrating a transformer according to an embodiment of the present disclosure.  FIG. 2B  is a schematic assembled view illustrating the transformer of  FIG. 2A . In this embodiment, the transformer of the present disclosure may be applied to a pulse transformer. As shown in  FIG. 2 , the transformer  2  comprises a bobbin  20 , at least one primary winding coil  21 , at least one secondary winding coil  22 , and a magnetic core assembly  27 . The at least one primary winding coil  21  and the at least one secondary winding coil  22  are wound around the bobbin  20 . The bobbin  20  comprises a main body  23 , plural extension structures  24 , and plural pin groups. The main body  23  comprises a channel  230 , plural winding sections  233 , a first connecting seat  235 , and a second connecting seat  236 . The channel  230  runs through the main body  23 . The at least one primary winding coil  21  and the at least one secondary winding coil  22  are wound around the plural winding sections  233 . The first connecting seat  235  and the second connecting seat  236  are located at two opposed sides of the main body  23 . The main body  23  further comprises plural partition plates  231  and two lateral plates  232 . The two lateral plates  232  are located at the two opposed sides of the main body  23 . The plural partition plates  231  are disposed on the main body  23  and arranged between the two lateral plates  232  at regular spacing intervals or irregular spacing intervals. In addition, the plural partition plates  231  are parallel with each other. Consequently, the plural winding sections  233  are defined by the plural partition plates  231  and the two lateral plates  232  collaboratively. In this embodiment, the plural winding sections  233  comprise plural first winding sections  233   a  and plural second winding sections  233   b . The plural first winding sections  233   a  are located at bilateral sides of the plural second winding sections  233   b . The at least one primary winding coil  21  is wound around the first winding sections  233   a  of the bobbin  20 . The at least one secondary winding coil  22  is wound around the second winding sections  233   b  of the bobbin  20 . In this embodiment, the bobbin  20  comprises two first winding sections  233   a  and two second winding sections  233   b . It is noted that the numbers of the first winding sections  233   a  and the second winding sections  233   b  may be varied according to the practical requirements. 
     In this embodiment, the plural extension structures  24  comprise a first extension structure  240  and a second extension structure  241 . The first extension structure  240  is connected with the first connecting seat  235  of the main body  23 . The second extension structure  241  is connected with the second connecting seat  236  of the main body  23 . In this embodiment, the first extension structure  240  and the second extension structure  241  are integrally extended from the first connecting seat  235  and the second connecting seat  236  of the main body  23 , respectively. In addition, the first extension structure  240  and the second extension structure  241  are parallel with each other, and extend from the same side of the first connecting seat  235  and the second connecting seat  236 . Take the first extension structure  240  for example. Along a direction distant from the main body  23  (e.g. along the direction A), at least one first notch  2401  and at least one first stepped structure  2402  are sequentially formed on the top surface of the first extension structure  240 . The first notch  2401  is defined by a flank of the first connecting seat  235  and a stopping plate  2403  of the first extension structure  240  collaboratively. The first stepped structure  2402  is formed on the top surface of the first extension structure  240 , and the first stepped structure  2402  comprises plural stepped parts whose altitudes are gradually decreased along the direction A. Please refer to  FIGS. 2A and 2B . In this embodiment, the first stepped structure  2402  comprises a first stepped part  2402   a  and a second stepped part  2402   b . (In other embodiments, the first stepped structure  2402  may comprise more stepped parts.) Moreover, the stopping plate  2403  is arranged between the first stepped part  2402   a  of the stepped structure  2402  and the first notch  2401 . The altitude of the stopping plate  2403  is higher than the surface of the first stepped part  2402   a . Due to the altitude difference between the stopping plate  2403  and the first stepped part  2402   a , the region between the stopping plate  2403  and the first stepped part  2402   a  may be defined as a first wire-managing part  2404 . Due to the altitude difference between the first stepped part  2402   a  and the second stepped part  2402   b , the region between the first stepped part  2402   a  and the second stepped part  2402   b  may be defined as a second wire-managing part  2405 . The first wire-managing part  2404  and the second wire-managing part  2405  are used for disposing different segments of the secondary winding coil  22  in order to manage the secondary winding coil  22 . 
     In this embodiment, the second extension structure  241  also comprises at least one second notch  2411 , at least one second stepped structure  2412 , and a stopping plate  2413 . Similarly, the second stepped structure  2412  also comprises a first stepped part  2412   a  and a second stepped part  2412   b . Similarly, due to the altitude difference between the stopping plate  2413  and the first stepped part  2412   a , the region between the stopping plate  2413  and the first stepped part  2412   a  may be defined as a first wire-managing part  2414 . Similarly, due to the altitude difference between the first stepped part  2412   a  and the second stepped part  2412   b , the region between the first stepped part  2412   a  and the second stepped part  2412   b  may be defined as a second wire-managing part  2415 . Similarly, the first wire-managing part  2414  and the second wire-managing part  2415  are used for disposing different segments of the secondary winding coil  22  in order to manage the secondary winding coil  22 . 
     Please refer to  FIGS. 2A and 2B  again. The plural pin groups of the bobbin  20  comprise plural first pin groups  25  and plural second pin groups  26 . The plural first pin groups  25  are disposed on the outer surfaces of the first connecting seat  235  and the second connecting seat  236  of the main body  23 . The outlet terminals of the primary winding coil  21  are wound around and fixed on the plural first pin groups  25 . The plural second pin groups  26  are disposed on the outer surfaces of the first extension structure  240  and the second extension structure  241 . The outlet terminals of the secondary winding coil  22  are wound around and fixed on the plural second pin groups  26 . In some embodiments, the plural pins of the first pin group  25  on the first connecting seat  235  and the plural pins of the first pin group  25  on the second connecting seat  236  are arranged in an asymmetric form or a staggered form. Alternatively, the number of the plural pins of the first pin group  25  on the first connecting seat  235  may be different from the number of the plural pins of the first pin group  25  on the second connecting seat  236 .  FIG. 3  is a schematic top view illustrating the transformer of  FIG. 2B . As shown in  FIG. 3 , the number of the plural pins of the first pin group  25  on the first connecting seat  235  is different from the number of the plural pins of the first pin group  25  on the second connecting seat  236 . Since the plural pins of the first pin group  25  are specially arranged, the plural pins of the first pin group  25  may provide a foolproof positioning function. When the transformer  2  is mounted on a circuit board (not shown), the possibility of erroneously inserting the pins into the unmatched conductive holes of the circuit board will be minimized. Moreover, each of the plural second pin groups  26  comprises plural pins  261  and  262  corresponding to the stepped parts  2402   a  and  2402   b , respectively, or corresponding to the stepped parts  2412   a  and  2412   b , respectively. In this embodiment, each of the plural second pin groups  26  comprises two pins. It is noted that the number of the pins of the second pin group  26  may be varied according to the practical requirements. 
     Please refer to  FIGS. 2A and 2B  again. The magnetic core assembly  27  comprises a first magnetic part  270  and a second magnetic part  271 . The first magnetic part  270  comprises a middle portion  270   a  and two leg portions  270   b . The second magnetic part  271  also comprises a middle portion  271   a  and two leg portions  271   b . In this embodiment, the first magnetic part  270  and the second magnetic part  271  are E cores, so that the magnetic core assembly  27  is an EE-type magnetic core assembly. In some embodiments, the first magnetic part  270  and the second magnetic part  271  of the magnetic core assembly  27  are collaboratively defined as a UI-type magnetic core assembly or an EI-type magnetic core assembly. Moreover, in this embodiment, the middle portion  270   a  of the first magnetic part  270  and the middle portion  271   a  of the second magnetic part  271  are embedded into the channel  230  of the main body  23 . 
     Please refer to  FIGS. 2A and 2B  again. The primary winding coil  21  has outlet terminals  211  and  212 , and the secondary winding coil  22  has outlet terminals  221  and  222 . A process of assembling the transformer  2  will be illustrated as follows. Firstly, the primary winding coil  21  and the secondary winding coil  22  are respectively wound around the first winding sections  233   a  and the second winding sections  233   b  of the bobbin  21 . Then, the outlet terminals  211  and  212  of the primary winding coil  21  are directed through corresponding guiding recesses at the bottom of the first connecting seat  235  of the main body  23  of the bobbin  20 . Then, the outlet terminals  211  and  212  of the primary winding coil  21  are respectively wound around and fixed on the pins  251  and  252  of the first pin group  25 , which are disposed on the first connecting seat  235 . The outlet terminals  221  and  222  of the secondary winding coil  22  come out from the bottom of the main body  23 . The outlet terminal  221  of the secondary winding coil  22  is directed through the first wire-managing part  2404  of the first extension structure  240  and fixed on the pin  261  of the second pin group  26 . The outlet terminal  222  of the of the secondary winding coil  22  is directed through the second wire-managing part  2405  of the first extension structure  240  and fixed on the pin  262  of the second pin group  26 . In this embodiment, the ways of winding, managing and fixing another primary winding coil  21  and another secondary winding coil  22  on the second connecting seat  236  and the second extension structure  241  of the bobbin  20  are similar to those of the primary winding coil  21  and the secondary winding coil  22  mentioned above, and are not redundantly described herein. After the primary winding coils  21  and the secondary winding coils  22  are fixed on the pin groups  25  and  26 , the middle portion  270   a  of the first magnetic part  270  and the middle portion  271   a  of the second magnetic part  271  are embedded into the channel  230  of the main body  23 , and the leg portions  270   b  and  271   b  are located at bilateral sides of the main body  23  of the bobbin  20 . Meanwhile, the transformer  2  is assembled. 
     From the above description, the bobbin  20  of the transformer  2  of the present disclosure has plural extension structures  24 . The plural extension structures  24  comprise the notches  2401 ,  2411  and the stepped structures  2402 ,  2412 . So that when the volume of the bobbin  20  of the transformer  2  of the present disclosure is equal to the volume of the bobbin of the conventional transformer, the arrangement of the notches  2401  and  2411  can increase the creepage distance between the magnetic core assembly  27  and the secondary winding coil  22 . In other words, the overall volume of the transformer  2  of the present disclosure may be reduced with the proviso that the creepage distance of the transformer  2  meets the electric safety regulations. Moreover, due to the stepped parts  2402   a ,  2402   b ,  2412   a  and  2412   b  of the stepped structures  2402  and  2412  of the extension structures  24  of the bobbin  20 , it is not necessary to use the insulating tubes to separate the outlet terminals  221  and  222  of the secondary winding coil  22  from each other. Moreover, since the creepage distance between the outlet terminals  221  and  222  of the secondary winding coil  22  may be increased to meet the electric safety regulations, the possibility of generating the arching effect at the regions between the outlet terminals  221  and  222  of the secondary winding coil  22  and the pins  261  and  262  will be minimized. Moreover, since the first wire-managing parts  2404 ,  2414  and the second wire-managing parts  2405 ,  2415  may be used for storing the segments of the secondary winding coil  22 , the efficacy of protecting and managing the secondary winding coil  22  can be reached. Moreover, the transformer  2  of the present disclosure has good electrical properties and may be fabricated by an automatic winding method. Moreover, by adjusting the arrangements or the numbers of the plural pins of the first pin group  25  on the first connecting seat  235  and the plural pins of the first pin group  25  on the second connecting seat  236 , the transformer  2  may have a foolproof positioning mechanism. 
     While the disclosure has been described in terms of what is presently considered to be the most practical and preferred embodiments, it is to be understood that the disclosure needs not be limited to the disclosed embodiment. On the contrary, it is intended to cover various modifications and similar arrangements included within the spirit and scope of the appended claims which are to be accorded with the broadest interpretation so as to encompass all such modifications and similar structures.