Leakage transformer

Abstract

To provide a leakage transformer capable of effectively and easily suppressing a temperature rising of an internal part of a transformer while reducing the size of the transformer in a state of filling a resin.SOLUTION: In a body part 10, a bobbin 2 includes a plurality of flange parts that is adjacent to a plurality of places corresponded to a winding end part 15 of a primary coil 4 and / or a secondary coil 5 to be wound, and each flange part has a first flange part 6 that separates the primary coil and the secondary coil. A case 11 with a bottom for housing the body part 10 is provided, and the body part 10 is embedded into a filling material 20. On a coil adjacent surface 16 of at least one flange part from the plurality of flange parts, an uneven pattern part 7 in which a plurality of convex parts 7b and a plurality of concave parts 7a are extended to a long direction Z in an almost parallel is formed, and the filling material 20 is introduced to coils 4 and 5 that are adjacent while being extended to the long direction Z of each flange part and passing the concave parts 7a that serves as a groove-like path.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a leakage transformer in which a primary coil and a secondary coil, each wound around a bobbin, are separated by a flange to form a leakage inductance. [Background technology]

[0002] Generally, a leakage transformer has a large leakage inductance achieved by separating the primary and secondary coils, which are wound around a bobbin attached to a core, by the insulating flange (wall) of the bobbin, and is used in devices that utilize this leakage inductance, such as switching power supplies.

[0003] A known leakage transformer includes, for example, a cylindrical insulating bobbin, a core inserted into an insertion hole of the bobbin, a primary coil and a secondary coil wound around the outside of the bobbin, and terminals connected to these coils, with the bobbin provided with flanges on both ends as well as a separator (wall) to physically separate the primary coil and secondary coil (for example, Patent Document 1).

[0004] In addition, resin-filled transformers have also been known in the past, in which the bobbin, core, and primary and secondary coils are housed in a case and embedded in a filler such as resin to improve heat dissipation effects inside the transformer and to prevent insulation failure due to moisture.

[0005] 9 is a vertical cross-sectional view of a conventional resin-filled transformer. A primary coil 24 and a secondary coil 25, each wound around a bobbin 22, are physically separated by an insulating wall 26 of the bobbin 22 (section winding), and are embedded in a filler material within a case 31.

[0006] In recent years, switching power supplies and the like have become smaller, and this has led to demands for smaller transformers as well. For this reason, coils are wound in multiple layers with no gaps across the bobbin width and with a high space factor.

[0007] On the other hand, transformers have heat resistance standards depending on the insulating materials (paint and resin) used in the coil, and they must be kept below the specified allowable temperature. In this case, if the transformer is made larger, the temperature rise is suppressed and it is easier to keep the temperature below the allowable temperature. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2011-124337 A Summary of the Invention [Problem to be solved by the invention]

[0009] However, as shown in FIG. 8, in order to miniaturize the transformer, the primary coil 24 and the secondary coil 25 are each wound around the bobbin 22 in multiple layers with a high space factor. Therefore, when the filler is poured into the case 31, it is difficult for the filler to be introduced inside the wound coils 24, 25, for example, to a location such as the center A (dashed line) near the outer cylinder surface of the bobbin (above the coil in the figure).

[0010] As a result, the heat dissipation ability of this center A becomes poor, the temperature rises easily, and the inside of the transformer becomes hot. In this case, there is a risk that the allowable temperature of the leakage transformer will be exceeded, or safe continuous operation will be hindered, and it may be difficult to suppress the temperature rise below the allowable temperature.

[0011] An object of the present invention is to provide a leakage transformer that can easily and effectively suppress a temperature rise inside the transformer while being miniaturized in a resin-filled state. [Means for solving the problem]

[0012] In order to achieve the above object, the leakage transformer of the present invention comprises a cylindrical bobbin, a core inserted into an insertion hole of the bobbin, and a coil body wound around the bobbin to form a primary coil and a secondary coil, respectively, the bobbin having a plurality of flange portions provided adjacent to a plurality of positions corresponding to the winding ends of the primary coil and / or the secondary coil, the flange portions including a first flange portion separating the primary coil and the secondary coil in the axial direction of the bobbin, a main body, and a bottomed case provided with a space with an opening for accommodating the main body. An uneven pattern portion having multiple convex portions and concave portions extending approximately parallel to each other in the longitudinal direction is formed on the coil-adjacent surface of at least one of the multiple flange portions, the main body portion is embedded in a filler material within the case, the filler material is introduced into a groove-like passage formed by the concave portions of the flange portions, and the filler material is filled and formed in the coil gaps of the coil body.

[0013] According to this configuration, the primary coil and the secondary coil are separated in the axial direction by the first flange to form a leakage inductance, and a concave-convex pattern with multiple convex and concave portions extending substantially parallel to each other in the longitudinal direction is formed on the coil-adjacent surface of at least one flange, and the filler is introduced into the adjacent coil through the concave portions that extend in the longitudinal direction of the flange and serve as groove-like passages. Therefore, since the flange includes the concave-convex pattern portion for introducing the filler, no separate external introduction passage is provided, making it possible to reduce the size accordingly, and it is possible to easily and effectively suppress the temperature rise inside the transformer while miniaturizing the leakage transformer.

[0014] In the present invention, it is preferable that at least one of the plurality of recesses extending in the longitudinal direction is fixed in a direction such that an extension line of the longitudinal direction passes through the case opening surface defined by the case opening. In this case, the filler is easily introduced from the case opening through the recess of the flange portion to the adjacent coil, and it is possible to more easily effectively suppress the temperature rise inside the transformer while miniaturizing the leakage transformer.

[0015] In the present invention, it is preferable that at least one of the longitudinal directions of the recesses is substantially aligned with the vertical direction perpendicular to the case opening. In this case, the filler can be more easily introduced from the case opening through the recesses in the flange from above to below, and the leakage transformer can be made smaller and the temperature rise inside the transformer can be more easily and effectively suppressed.

[0016] Furthermore, in the present invention, it is preferable that all of the longitudinal directions of the recesses are substantially aligned with the vertical direction perpendicular to the case opening. In this case, the filler can be more easily introduced from the case opening through the recesses in the flange from above to below, making it possible to more easily and effectively suppress temperature rise inside the transformer while miniaturizing the leakage transformer.

[0017] In the present invention, the axial direction of the bobbin may be substantially aligned with the vertical direction perpendicular to the case opening, and at least one of the longitudinal directions of the recesses may be substantially aligned with the horizontal direction perpendicular to the vertical direction. In this case, the filler is introduced through the recesses that extend in the longitudinal direction (horizontal direction) and serve as groove-like passages, so that the leakage transformer can be made compact while easily and effectively suppressing temperature rise inside the transformer.

[0018] In the present invention, it is also preferable that the concave-convex pattern portion is formed on both sides of the coil adjacent surface of the first flange portion that separates the primary coil and the secondary coil in the axial direction. In this case, since the first flange portion that separates the primary coil and the secondary coil includes the concave-convex pattern portion into which a filler is introduced, it is possible to more easily suppress the temperature rise of the coil while reducing the size.

[0019] Preferably, a predetermined leakage inductance is formed by the axial thickness of the first flange portion or the axial thickness determined by the convex surfaces of both sides of the concave-convex pattern portion formed on the coil-adjacent surface of the first flange portion. Therefore, a predetermined leakage inductance is formed, and the coil temperature rise can be easily suppressed while being miniaturized.

[0020] Preferably, the primary coil and the secondary coil are wound in an aligned multi-layer manner, which makes it easier to obtain a predetermined leakage inductance required by an on-board circuit. Effect of the Invention

[0021] In the present invention, the first flange separates the primary coil and the secondary coil in the axial direction to form a leakage inductance, and at least one flange has a concave-convex pattern with multiple convex and concave portions extending substantially parallel to each other in the longitudinal direction on its coil-adjacent surface, and the filler material is introduced into the adjacent coil through the concave portions that extend in the longitudinal direction of the flange and serve as groove-like passages. Therefore, since the flange includes the concave-convex pattern portion for introducing the filler material, no separate external introduction passage is provided, making it possible to reduce the size accordingly, and it is possible to easily and effectively suppress the temperature rise inside the transformer while miniaturizing the leakage transformer. [Brief description of the drawings]

[0022] [Figure 1] 1 is a schematic vertical cross-sectional view showing a leakage transformer according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a perspective view of a bobbin of the leakage transformer. [Diagram 3] FIG. 2 is a perspective view of a core of the leakage transformer. [Figure 4] FIG. 2 is a perspective view of the leakage transformer. [Diagram 5] FIG. 2 is a perspective view of a main part of the leakage transformer. [Figure 6] FIG. [Figure 7] FIG. 2 is a schematic perspective view of the leakage transformer of FIG. [Figure 8] FIG. 13 is a schematic vertical cross-sectional view showing a leakage transformer according to a modified example. [Figure 9] FIG. 1 is a schematic vertical cross-sectional view showing a conventional leakage transformer. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic vertical cross-sectional view of a leakage transformer 1 according to one embodiment of the present invention. As shown in FIG. 1, the leakage transformer 1 includes a body 10 including an insulating cylindrical bobbin 2, a core 3 inserted into an insertion hole 12 of the bobbin 2, and a coil body forming a primary coil 4 and a secondary coil 5 wound and laminated on the outside of the bobbin 2, and a bottomed case 11 that houses the body 10 and has a space with an opening 11A that opens upward. The case 11 also includes terminals (not shown) connected to the coils 4 and 5, respectively. The body 10 is embedded in a filler material in the case 11, and the bottom of the case 11 is placed on the board mounting surface Ka of the board K.

[0024] The main body 10 further has a first flange (wall) 6 disposed between the primary and secondary coils 4 and 5 formed on the bobbin 2 to separate them in the axial direction X of the bobbin 2, and second and third flanges 8 and 9 formed on both ends of the first flange 6. These flanges 6, 8, and 9 are provided adjacent to a plurality of locations corresponding to winding ends (both ends in the axial direction X) 15 of the primary coil 4 and / or secondary coil 5 wound and stacked around the bobbin 2. The primary coil 4 and secondary coil 5 are wound, for example, in an aligned multi-layered manner (section winding).

[0025] The main body 10 is embedded in a filler in the case 11 to obtain a heat dissipation effect inside the transformer and to prevent insulation failure due to moisture. For example, gel-like silicone resin or epoxy resin is used as the filler. The case 11 is made of, for example, polycarbonate (PC), polyethylene terephthalate (PET), or metal material.

[0026] 2 to 6 are exploded views of the leakage transformer 1 before it is housed in the case. FIG. 2 is a perspective view showing the bobbin 2. The bobbin 2 is cylindrical, and has flanges 8 and 9 formed at both ends in the axial direction X, and a first flange 6 for separating the coils 4 and 5. In FIG. 1, the axial direction X of the bobbin 2 is substantially aligned with the horizontal direction, similar to a case opening surface 11Aa of a case opening 11A described later. The bobbin 2 and the flanges 6, 8, and 9 are made of insulating resin such as polyethylene terephthalate (PET) or phenol (PF).

[0027] The center legs 3a, 3b of a PQ type core 3 (3A, 3B) as shown in Fig. 3 are inserted into the insertion hole 12 of the bobbin 2 as shown in Fig. 6 (Fig. 1). The core 3 used has a center leg, and in addition to the PQ type, EE type and EER type cores are also used. In this example, there is no gap between the center legs 3a, 3b as in Fig. 1.

[0028] As shown in FIG. 1, in this example, the concave-convex pattern portion 7 is formed on both sides of the coil adjacent surface 16 (the side surface that contacts the winding end portion 15) of the first flange portion (wall portion) 6 that separates the primary coil 4 and the secondary coil 5, and as shown in FIG. 2, a plurality of convex portions 7b and concave portions 7a are formed so as to be juxtaposed in a left-right direction (the outer peripheral direction of the flange portion) Y perpendicular to the axial direction X and extend approximately parallel to each other in a longitudinal direction (up-down direction) Z.

[0029] 1, the filler extends in the longitudinal direction (up-down direction) Z of the first flange portion 6 and is introduced into the adjacent coils 4, 5 through recesses 7a formed between the protrusions 7b as groove-like passages, and is filled in the coil gaps S that are gaps between the wires of each wound and stacked coil. The filler is filled in the manufacturing process and hardened and formed in the hardening process.

[0030] As shown in FIG. 1, the uneven portion 7 extends in the longitudinal direction (vertical direction) Z, which is the lamination direction of the coils 4 and 5, so that the filler poured from the opening 11A passes through the groove-shaped recesses 7a of the uneven portion 7 formed on both sides of the first flange 6, and is introduced to a place where it was difficult to introduce the filler, such as the center A near the bobbin outer cylinder surface (the upper side of the coil in the figure), which was difficult to introduce in the past. Also, the filler is easily introduced through the groove-shaped recesses 7a of the uneven portion 7 to the lower side of the coil near the bobbin outer cylinder surface. In this way, the filler is introduced to the adjacent coils 4 and 5 through the groove-shaped recesses 7a formed in the first flange 6, so that the filler is introduced by the uneven portion 7 formed in the first flange 6 without providing a separate introduction path on the outside, and therefore the leakage transformer 1 can be made compact.

[0031] The multiple recesses 7a extending in the longitudinal direction (up-down direction) Z are fixed in a direction in which an extension line of the longitudinal direction Z passes through the case opening surface 11Aa defined by the case opening 11A. In this case, the filler is easily introduced from the case opening 11A through the recesses 7a of the flange portion 6 into the adjacent coils 4, 5. In this example, the extension lines of all of the multiple recesses 7a pass through the opening surface 11Aa, but it is also possible that at least one of the recesses 7a passes through.

[0032] In addition, the longitudinal direction of the plurality of recesses 7a is approximately aligned with the vertical direction Z, which is perpendicular to the mounting surface when the bottom of the case is placed on the mounting surface of the substrate. In this case, the filler is easily introduced from above to below through the recesses 7a of the flange 6 from the case opening 11A. In this example, all of the longitudinal directions of the plurality of recesses 7a are approximately aligned with the vertical direction Z, but at least one of the recesses 7a may be approximately aligned. Here, approximately aligned includes a directional deviation of preferably within 10°, more preferably within 5°, in addition to a perfect alignment of the directions. Also, a directional deviation exceeding the above-mentioned numerical value is permitted, for example, when the recesses 7a have an effect of discharging air bubbles or are easy to impregnate with a filler.

[0033] A predetermined leakage inductance is formed by the axial thickness determined by the surfaces of the convex portions on both sides between the convex portions 7b (FIG. 4) of the uneven pattern portion 7 formed on both sides of the first flange portion (wall portion) 6. The primary coil 4 and the secondary coil 5 are wound, for example, in an aligned manner, so that the predetermined leakage inductance required by the circuit is easily obtained. In addition, since the leakage inductance is formed by the axial thickness of the first flange portion 6, it is little affected by changes in the gap between the center legs 3a, 3b, but a gap may be provided as necessary.

[0034] As shown in Fig. 4, the primary coil 4 is wound without gaps between the first flange 6 and the second flange 8 on which the uneven portion 7 is formed, and as shown in Fig. 5, the secondary coil 5 is wound without gaps between the first flange 6 and the third flange 9, and both coils 4, 5 are wound without gaps around the bobbin 2. As shown in Fig. 6, the primary coil 4 is wound in multiple layers, and the secondary coil 5 (not shown) is also wound in multiple layers.

[0035] In this way, the primary coil 4 is wound in multiple layers with no gaps between the second flange portion 8 and the first flange portion (wall portion) 6 of the bobbin 2, and the secondary coil 5 is wound in multiple layers with no gaps between the third flange portion 9 and the first flange portion 6, and are arranged with a high space factor within the bobbin 2.

[0036] 7 shows the state in which the main body 10 assembled as described above is housed in the case 11 and embedded in the filler 20. At this time, as shown in Figs. 1 and 2, the filler 20 passes through the recesses 7a of the concave-convex pattern portion 7 formed in the first flange 6 and is introduced into the adjacent coils 4 and 5 at locations that were previously difficult to reach, making it possible to effectively suppress a temperature rise inside the transformer.

[0037] In this way, in the leakage transformer 1 of the present invention, the first flange 6 separates the primary coil 4 and the secondary coil 5 in the axial direction X to form a leakage inductance, and the uneven pattern 7 having a plurality of convex portions 7b and concave portions 7a extending approximately parallel to each other in the longitudinal direction Z is formed on both sides of the coil-adjacent surface 16 of the first flange 6, and the filler 20 is introduced in the longitudinal direction (up-down direction) Z through the groove-like concave portions 7a of the uneven pattern 7 to the adjacent coils 4, 5. Therefore, since the first flange 6 includes the uneven pattern 7 for introducing the filler 20, no separate external introduction path is provided, which allows the transformer to be made smaller accordingly, and the leakage transformer can be made smaller while still effectively suppressing the temperature rise inside the transformer.

[0038] 8 is a schematic vertical cross-sectional view showing a leakage transformer 1A of a modified example. This leakage transformer 1A is obtained by storing the main body 10 of FIG. 1 in a case 11 by tilting it 90 degrees, and the uneven pattern section 7 is formed so that the convex parts 7b and the concave parts 7a are arranged in a depth direction Y perpendicular to the axial direction (vertical direction) X of the bobbin 2 and extend substantially parallel in the longitudinal direction (left-right direction) Z. That is, unlike the axial direction of the bobbin 2 in FIG. 1 which substantially coincides with the horizontal direction, in this leakage transformer 1A of the modified example, the axial direction of the bobbin 2 substantially coincides with the vertical direction X, and the longitudinal direction of the plurality of concave parts 7a substantially coincides with the horizontal direction Z perpendicular to the vertical direction X. Similarly, the bottom of the case 11 is placed on the board mounting surface Ka of the board K. The other configurations are the same as those in FIG. 1.

[0039] In this case, the filler 20 poured in from the opening 11A extends from the longitudinal direction (left-right direction) Z to the longitudinal direction (left-right direction) Z of the uneven pattern portion 7 through the recess 7a which forms a groove-like passage and is introduced to the location (A1) near the coil outer tube surface of the adjacent coils 4, 5. Similarly, this makes it possible to easily and effectively suppress the temperature rise inside the transformer while miniaturizing the leakage transformer.

[0040] Note that, instead of providing a concave-convex pattern on both coil-adjacent surfaces of the first flange (wall) 6 in each embodiment, a concave-convex pattern may be provided on only one of the coil-adjacent surfaces. Also, a concave-convex pattern may be provided on the coil-adjacent surfaces of one or both of the second and third flanges 8, 9 together with the concave-convex pattern on the first flange 6 or without providing a concave-convex pattern on the first flange.

[0041] Also, in this embodiment, the main body is housed in a case, but if the resin filler can maintain a stable shape after filling, the case may be omitted.

[0042] In this embodiment, the primary coil and the secondary coil are wound in an aligned multi-layered manner, but they may be wound in an oblique manner, which allows the coils to be wound with a higher space factor, making it possible to further reduce the size.

[0043] The present invention is not limited to the above-described embodiment, and various additions, modifications, and deletions are possible without departing from the scope of the present invention. Therefore, such modifications are also included in the scope of the present invention. [Explanation of symbols]

[0044] 1: Leakage transformer 2: Bobbin 3: Core 4: Primary coil 5: Secondary coil 6: First flange (wall) 7: Concave and convex pattern part 7a: Recess 7b: Convex part 8: Second flange 9: Third flange 10: Main body 11: Case 11A: Case opening 11Aa: Case opening surface 12:Through hole 15: Winding end 16: Coil adjacent surface 20: Filling material K: Substrate Ka: PCB mounting surface S: Coil gap X: Axial direction of the bobbin Y: Direction perpendicular to the axial direction of the bobbin Z: Longitudinal direction of the uneven pattern

Claims

1. a main body including a cylindrical bobbin, a core inserted into an insertion hole of the bobbin, and a coil body wound around the bobbin to form a primary coil and a secondary coil, the bobbin having a plurality of flanges provided adjacent to a plurality of positions corresponding to winding ends of the primary coil and / or the secondary coil, the flanges including a first flange separating the primary coil and the secondary coil in an axial direction of the bobbin; a case having a bottom and a space with an opening for accommodating the main body; a concave-convex pattern portion having a plurality of convex portions and concave portions extending substantially parallel to each other in a longitudinal direction is formed on a coil-adjacent surface of at least one of the plurality of flange portions, The main body is embedded in a filler material in the case, the filler is introduced into a groove-like passage formed by the recess of the flange, and the filler is filled in coil gaps of the coil body.

2. In claim 1, At least one of the plurality of recesses extending in the longitudinal direction is fixed in an orientation in which its longitudinal extension line passes through a case opening plane defined by an opening of the case.

3. In claim 2, At least one of the longitudinal directions of the plurality of recesses substantially coincides with an up-down direction perpendicular to the opening surface of the case.

4. In claim 2, A leakage transformer, wherein all of the longitudinal directions of the plurality of recesses are substantially aligned with a vertical direction perpendicular to the opening surface of the case.

5. In claim 1, A leakage transformer, wherein an axial direction of the bobbin is arranged to approximately coincide with an up-down direction perpendicular to the case opening surface, and at least one of the longitudinal directions of the multiple recesses approximately coincides with a horizontal direction perpendicular to the up-down direction.

6. In any one of claims 1 to 5, a concave-convex pattern portion formed on both sides of the coil-adjacent surface of the first flange portion that separates the primary coil and the secondary coil in the axial direction.

7. In any one of claims 1 to 5, A leakage transformer in which a predetermined leakage inductance is formed by an axial thickness of the first flange portion or an axial thickness determined by the convex surfaces on both sides of the uneven pattern portion formed on the coil adjacent surface of the first flange portion.

8. In claim 7, The leakage transformer, wherein the primary coil and the secondary coil are wound in an aligned multi-layer winding.

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