Bobbin and transformer device

Abstract

[Problem] To provide a bobbin that does not readily experience disruptions in winding position and makes it possible to stabilize and thereby suppress irregularity in winding position, even when a plurality of wires are simultaneously wound in a plurality of layers. [Solution] The present invention is a bobbin 10 that has: an annular step part 51 that has a first wall 41; and a second wall 42 and a third wall 43. The first wall 41 guides a winding 22a at a final turn 31 of a first layer that has been wound at an outer circumferential surface 12a of a cylindrical part 12. The step part 51 has a slope 51a from the end 31a of the winding 22a at the final turn 31 of the first layer to a winding 22b at a first turn 32 of a second layer and has a surface 51b at which the winding 22b at the first turn 32 of the second layer is wound. The second wall 42 guides the winding 22b at the first turn 32 of the second layer that has been wound at the step part 51, and the third wall 43 guides a winding 22c at a second turn 33 of the second layer from the end 32a of the winding 22b at the first turn 32 of the second layer.

Description

Bobbin and transformer device

[0001] The present invention relates to a bobbin used as a main body of a transformer coil, and a transformer device using the same.

[0002] There is a demand for transformers with a structure that can obtain leakage inductance to establish an LLC resonant circuit. Furthermore, to accommodate recent trends in compact, high-density packaging, the transformer itself must be made smaller. A split winding structure is employed as a way to obtain leakage inductance that satisfies the above requirements. To achieve a small, compact winding, it is necessary to wind the winding in two or more layers for one circuit. To control the winding position of wires with a large finished outer diameter, such as Litz wire, or to avoid leakage flux from the core gap, simply providing a guide on the first layer of winding is not always sufficient, and it has been necessary to provide a guide on the second layer as well. Related technology is disclosed in Patent Document 1.

[0003] As a result, in the case of a multiple-layer winding, such as in the case of a multiple-wire simultaneous winding configuration, the winding position is easily distorted, the position of the electric wire becomes unstable, and the instability of the winding position can cause variations in the winding position and result in unstable characteristics.

[0004] Furthermore, resonant converters have been used in chargers for plug-in hybrid vehicles (PHVs), for example. These resonant converters utilize resonance with a capacitor connected to a transformer to reduce current noise and improve conversion efficiency. For transformers used in resonant converters, adjusting design parameters such as the winding width, number of turns, bobbin diameter, and core gap is crucial to achieving a desired resonant inductance (excitation inductance and leakage inductance).

[0005] Conventionally, bobbins used in such transformer coils have been known that have a first cylindrical portion around which a primary winding is wound and a second cylindrical portion around which a secondary winding is wound, arranged side by side in the axial direction, and that have a separator portion that separates the first cylindrical portion from the second cylindrical portion in the axial direction (see, for example, Patent Documents 2 and 3).

[0006] In the conventional bobbins described above, the inner winding portion near the center of the core is inherently prone to trapping heat, and in order to ensure a heat dissipation path, it was necessary to stably penetrate the potting heat dissipation resin up to the first layer of the winding.

[0007] Furthermore, with the conventional bobbins described above, the first layer of winding is wound near the core gap, which causes eddy current loss in the winding due to the influence of leakage magnetic flux from the core gap, resulting in heat generation. In addition, the winding position varies depending on the winding method, which causes fluctuations in the electrical coupling characteristics of the transformer. This can lead to unintended fluctuations in the power supply characteristics, which can deteriorate the characteristics and reduce efficiency, affecting the winding components and causing phenomena such as abnormal heating in the winding.

[0008] JP 2023-125515 A JP 2017-183524 A JP 2022-141446 A

[0009] Various aspects of the present invention aim to provide a bobbin and a transformer device that are less likely to lose their winding position even when multiple wires are wound simultaneously in multiple layers, and that can suppress variations in winding position by stabilizing the winding position, thereby reducing the effects of unstable characteristics. Various aspects of the present invention also aim to provide a bobbin and a transformer device equipped with the same that can improve heat dissipation efficiency. Various aspects of the present invention also aim to provide a bobbin and a transformer device equipped with the same that can suppress phenomena such as abnormal heat generation in the winding due to the effects of leakage magnetic flux, and can also improve heat dissipation efficiency.

[0010] Various aspects of the present invention are described below.

[0011] [1] A bobbin comprising: a separator that electrically insulates a primary winding from a secondary winding; and a winding position adjustment portion that is formed adjacent to the separator and that adjusts the winding position of at least one of the primary winding and the secondary winding.

[0012] [2] The bobbin described in [1] above, characterized in that the winding position adjustment unit adjusts the winding position so as to avoid eddy current loss caused in the primary winding or the secondary winding by magnetic flux present outside the bobbin.

[0013] [3] A winding position adjusting portion has a cylindrical portion around which at least one of the primary winding and the secondary winding is wound in two or more layers, the winding position adjusting portion is an annular stepped portion with a first wall protruding like a flange from the outer peripheral surface of the cylindrical portion, and has a second wall and a third wall located on the stepped portion, the first wall guides the final turn of the first layer wound around the outer peripheral surface of the cylindrical portion, the annular stepped portion is located next to the position where the final turn of the first layer is wound, has a slope from the end of the final turn of the first layer to the first turn of the second layer, and has a surface around which the first turn of the second layer is wound, the second wall guides the first turn of the second layer wound around the stepped portion, and the third wall guides the second turn of the second layer from the end of the first turn of the second layer, 2. The bobbin according to claim 1, wherein the third wall guides the second turn of the winding in the second layer so that the second turn of the winding is wound adjacent to the first turn of the winding in the second layer and above the final turn of the winding in the first layer.

[0014] According to the bobbin [3] of one aspect of the present invention, in a bobbin having a cylindrical portion on which a winding is wound in two or more layers, the second winding layer tends to run onto the third winding layer, causing instability in the overlapping winding position. To address this issue, the first wall guides the final turn of the first winding layer, the first turn of the second winding layer is wound around the annular step, and the third wall guides the second turn of the second winding layer from the end of the first turn of the second winding layer. In other words, the third wall is a guide provided at the winding position where the second turn of the second winding layer intersects with the first turn of the second winding layer, making it possible to guide the second turn of the second winding layer to the winding position and preventing the second turn of the second winding layer from running onto the third winding layer above the first turn of the second winding layer. This guide structure makes it possible to control the winding position, preventing the second layer winding position from becoming distorted. Stabilizing the winding position reduces variations in winding position, contributing to stabilizing characteristics.

[0015] [4] In the bobbin described in [3] above, the tubular portion includes the separate portion having the second wall and the third wall, the tubular portion has a second tubular portion on the step portion side and a first tubular portion on the opposite side of the step portion with respect to the separate portion, the second wall is formed on a surface perpendicular to the axial direction of the tubular portion, one end of the third wall is connected to the second wall and the other end is located on the second tubular portion side, the winding is a secondary winding, the first tubular portion is wound with a primary winding, and the second tubular portion is wound with the secondary winding.

[0016] According to the bobbin of the present invention described above in [4], the cylindrical portion includes a separate portion having a second wall and a third wall, and includes a second cylindrical portion on the step side of the separate portion and a first cylindrical portion on the opposite side of the step. The primary winding is wound around the first cylindrical portion, and the secondary winding is wound around the second cylindrical portion. The thicknesses of the molded second and third walls are equalized, and one end of the third wall is connected to the second wall and the other end is located on the second cylindrical portion side, creating a space in the first cylindrical portion opposite the third wall, forming an opening. When potting with heat-dissipating resin, this opening serves as a resin injection inlet and can be filled with heat-dissipating resin, contributing to heat dissipation.

[0017] [5] The bobbin according to the above [4], characterized in that a core hole is provided inside the outer circumferential surface, into which a core that forms a magnetic path between the primary winding and the secondary winding is inserted.

[0018] According to the bobbin of [3] above relating to one aspect of the present invention, by providing a core hole on the inside of the outer peripheral surface, a core that forms a magnetic path between the primary winding and the secondary winding can be inserted.

[0019] [6] The bobbin according to the above [3] or [4], wherein the step portion has a circumferential groove formed along the outer circumferential surface.

[0020] According to the bobbin of the above [6] according to one aspect of the present invention, since the step portion has a circumferential groove, when potting with a heat dissipation resin, the circumferential groove can be filled with the heat dissipation resin, and the filled portion becomes a heat dissipation path, which contributes to heat dissipation. In detail, when the bobbin is potted with a heat dissipation resin having a higher thermal conductivity than the material of the bobbin and the circumferential groove is filled with the resin, heat can be transferred to the heat dissipation destination more quickly, resulting in improved heat dissipation and excellent heat dissipation.

[0021] [7] A transformer device in which a primary winding and a secondary winding are wound around the outer peripheral surfaces of the first cylindrical portion and the second cylindrical portion of the bobbin described in [5] above, and a core is inserted into the core hole.

[0022] In order to solve the above-mentioned problem of improving heat dissipation efficiency, the present invention provides a bobbin having a first cylindrical portion around which a primary winding is wound and a second cylindrical portion around which a secondary winding is wound, which are connected in parallel in the same axial direction, and in which the outer peripheral surface of at least one of the first cylindrical portion or the second cylindrical portion has a concave lateral groove extending along the axial direction. Also, the winding position adjustment portion is an annular step portion on the outer peripheral surface of at least one of the first cylindrical portion or the second cylindrical portion that protrudes outward toward a wall surface of the separator portion.

[0023] With a bobbin of this configuration, the outer peripheral surface of at least one of the first cylindrical portion or the second cylindrical portion has a concave lateral groove extending along the axial direction, which allows potting heat dissipation resin to be efficiently supplied to the winding side of the cylindrical portion through the lateral groove.

[0024] Preferably, the lateral grooves of the bobbin are formed so as to recess inward from the outer circumferential surface.

[0025] According to the bobbin having this configuration, the lateral grooves are formed so as to be recessed inward from the outer peripheral surface, so that the potting heat dissipation resin can be reliably infiltrated into the lateral grooves.

[0026] Preferably, the bobbin has a core hole formed inside the outer circumferential surface into which a core that forms a magnetic path between the primary winding and the secondary winding is inserted.

[0027] With this bobbin configuration, the core can be inserted through the core hole.

[0028] It is also preferable that the core hole has, on its inner peripheral surface, a protrusion portion that extends along the axial direction and protrudes inward so as to correspond to a lateral groove that is formed so as to sink inward from the outer peripheral surface.

[0029] With this bobbin configuration, the protrusions ensure a certain distance between the winding and the core gap portion. Also, it is preferable that the inner peripheral surface has a plurality of protrusions extending along the axial direction in parallel with the protrusions.

[0030] The present invention also provides a transformer device in which a primary winding and a secondary winding are wound around the outer peripheral surface of the bobbin, and a core is inserted into the core hole.

[0031] According to the transformer device of this configuration, by using a bobbin having an annular step portion formed on the wall surface side of the separation portion that protrudes outward, it is possible to suppress phenomena such as abnormal heating of the windings due to the influence of leakage magnetic flux.

[0032] The present invention also provides a transformer device, wherein a clearance is formed between the core and the inner peripheral surface via the protrusion.

[0033] With this transformer device, a clearance is formed between the core and the inner peripheral surface via the protrusion, allowing the potting heat dissipation resin to penetrate into the clearance and ensuring a certain distance or more between the winding and the core gap portion.

[0034] The present invention provides a bobbin in which a first cylindrical portion around which a primary winding is wound and a second cylindrical portion around which a secondary winding is wound are connected and arranged side by side in the same axial direction, and the bobbin has a separator portion that protrudes like a flange from the connecting portion between the first cylindrical portion and the second cylindrical portion, thereby separating the first cylindrical portion from the second cylindrical portion, and the winding position adjustment portion is an annular step portion formed on the outer peripheral surface of at least one of the first cylindrical portion or the second cylindrical portion, protruding outward toward the wall surface of the separator portion.

[0035] With this bobbin, an annular step is formed adjacent to the separator that separates the first and second cylindrical portions, allowing the winding to be wound on the step at the final turn (end) of the first layer. This ensures a certain distance between the winding on the step and the core gap directly below the separator, reducing interference between the winding and leakage flux from the core gap. This prevents abnormal heating of the winding due to leakage flux.

[0036] It is also preferable that the step portion of the bobbin has a slope portion whose width gradually narrows as it approaches the wall surface of the separation portion.

[0037] With this bobbin, the stepped portion has a sloped portion, which allows the winding to be smoothly guided onto the stepped portion and allows the winding to be positioned uniformly, thereby further stabilizing the inductance characteristics of the transformer device.

[0038] In addition, it is preferable that the step portion of the bobbin has a circumferential groove extending along the outer periphery thereof.

[0039] With this bobbin configuration, the potting heat dissipation resin can be stably infiltrated through the circumferential groove of the step to the back of the winding that has climbed onto the step. In addition, the infiltration of the heat dissipation resin into the circumferential groove forms a heat dissipation path, thereby improving the heat dissipation efficiency of the winding.

[0040] Furthermore, it is preferable that the step portion of the bobbin has a lateral groove extending along the axial direction.

[0041] With this bobbin configuration, the potting heat dissipation resin can be efficiently supplied from the step portion to the winding side of the cylindrical portion via the lateral grooves in the step portion.

[0042] Furthermore, it is preferable that the bobbin has a lateral groove formed along the axial direction on the outer peripheral surface of the first tubular portion and / or the second tubular portion, and that the lateral groove of the first tubular portion and / or the second tubular portion is located on an extension line of the lateral groove of the step portion.

[0043] With this bobbin configuration, by forming a lateral groove in the step portion and a lateral groove in the cylindrical portion located on the extension of the lateral groove, the potting heat dissipation resin can be stably permeated through this series of lateral grooves to the back of the winding wound on the step portion and the cylindrical portion. In addition, the permeation of the heat dissipation resin into the lateral grooves forms a long heat dissipation path, which further improves the heat dissipation efficiency of the winding.

[0044] Preferably, the bobbin is formed so that at least one of the lateral grooves of the first cylindrical portion, the lateral grooves of the second cylindrical portion, and the lateral grooves of the stepped portion is recessed inward from the outer circumferential surface.

[0045] According to the bobbin having this configuration, the lateral grooves are formed so as to be recessed inward from the outer peripheral surface, so that the potting heat dissipation resin can be reliably infiltrated into the lateral grooves.

[0046] Preferably, the bobbin has a core hole formed inside the outer circumferential surface into which a core that forms a magnetic path between the primary winding and the secondary winding is inserted.

[0047] With this bobbin configuration, the core can be inserted through the core hole.

[0048] It is also preferable that the core hole has, on its inner peripheral surface, a protrusion that protrudes inward to correspond to a lateral groove that is formed so as to sink inward from the outer peripheral surface.

[0049] With this bobbin configuration, the protrusions ensure a certain distance or more between the winding and the core gap portion.

[0050] The present invention also provides a transformer device in which a primary winding and a secondary winding are wound around the outer peripheral surface of the first cylindrical portion and / or the second cylindrical portion of the bobbin, and a core is inserted into the core hole.

[0051] According to the transformer device of this configuration, by using a bobbin having an annular step portion formed on the wall surface side of the separation portion that protrudes outward, it is possible to suppress phenomena such as abnormal heating of the windings due to the influence of leakage magnetic flux.

[0052] The present invention also provides a transformer device, wherein a clearance is formed between the core and the inner peripheral surface via the protrusion.

[0053] With this transformer device, a clearance is formed between the core and the inner peripheral surface via the protrusion, allowing the potting heat dissipation resin to penetrate into the clearance and ensuring a certain distance or more between the winding and the core gap portion.

[0054] According to various aspects of the present invention, it is possible to provide a bobbin and a transformer device that are less likely to lose their winding position even when multiple wires are wound simultaneously in multiple layers, and that can suppress variations in winding position by stabilizing the winding position, thereby reducing the effects of unstable characteristics.

[0055] Furthermore, according to the present invention, by forming horizontal grooves or the like extending along the axial direction on the outer peripheral surface of at least one of the first and second cylindrical portions, potting heat dissipation resin can be efficiently supplied to the winding side of the cylindrical portion, thereby improving heat dissipation efficiency. Furthermore, by forming an annular step in contact with the separating portion of the bobbin, a certain distance or more is ensured between the winding on the step and the core gap portion directly below the separating portion, thereby reducing interference between the winding and leakage magnetic flux from the core gap portion. Therefore, phenomena such as abnormal heating of the winding due to the influence of leakage magnetic flux in the bobbin and the transformer device using it can be suppressed.

[0056] Furthermore, according to the present invention, by forming an annular step adjacent to the separate portion of the bobbin, a certain distance or more is ensured between the winding on the step and the core gap directly below the separate portion, thereby reducing interference between the winding and leakage flux from the core gap. This reduces problems such as abnormal winding heat generation due to the influence of leakage flux in the bobbin and the transformer device using it. Furthermore, by forming horizontal grooves or the like extending axially in the step of the bobbin, potting heat dissipation resin can be efficiently supplied from the step to the winding side of the cylindrical portion, improving heat dissipation efficiency.

[0057] 5 is a perspective view showing a bobbin according to one aspect of the present invention. (A) is a front view of the bobbin shown in FIG. 1, and (B) is a front view for explaining a method of winding a primary winding 21 and a secondary winding 22 around the bobbin shown in FIG. 1. FIG. 6 is a front view showing a comparative example to the bobbin shown in FIG. 1. FIG. 7 is an external perspective view of a bobbin according to one embodiment of the present invention. FIG. 8 is a top view of the bobbin as seen from the direction of arrow A in FIG. 4. FIG. 9 is a bottom view of the bobbin as seen from the direction of arrow C in FIG. 4. FIG. 10 is a cross-sectional view of the bobbin taken along line D-D in FIG. 1. FIG. 11 is a side view of a transformer coil with a winding wound around the bobbin. FIG. 12 is a schematic cross-sectional view of a transformer device according to one embodiment of the present invention.

[0058] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following description, and it will be readily understood by those skilled in the art that various changes in form and details can be made without departing from the spirit and scope of the present invention. Therefore, the present invention should not be interpreted as being limited to the description of the embodiments shown below.

[0059] (First embodiment) Fig. 1 is a perspective view showing a bobbin according to one aspect of the present invention. Fig. 2(A) is a front view of the bobbin shown in Fig. 1, and Fig. 2(B) is a front view for explaining a method of winding a primary winding 21 and a secondary winding 22 onto the bobbin shown in Fig. 1. Note that dashed lines 31a and 32a shown in Fig. 2(B) represent the positions where the final turn 31 of the first layer of winding 22a and the first turn 32 of the second layer of winding 22b are wound in a plan view, and the other dashed lines represent the positions where the other windings are wound.

[0060] The bobbin 10 shown in Figures 1 and 2(A) has a cylindrical portion 12 around which the winding 22 is wound in two or more layers. An annular step 51 is provided on the outer peripheral surface 12a of the cylindrical portion 12, and the annular step 51 protrudes from the outer peripheral surface 12 in a flange-like shape. The annular step 51 has a first wall 41, and a second wall 42 and a third wall 43 are provided on the annular step 51. The third wall 43 is located on the annular step 51 and is located on the opposite side of the first wall 41 across the step 51 (surface 51b of the step 51) in a plan view. The annular step 51 may also be referred to as a winding position adjustment portion.

[0061] 2B, the first wall 41 guides the wire 22a of the final turn 31 of the first layer wound around the outer circumferential surface 12a of the cylindrical portion 12. The annular step 51 is located adjacent to the position where the wire 22a of the final turn 31 of the first layer is wound. In other words, the first layer of wire 22a is guided and positioned by the first wall 41 during winding.

[0062] The annular step 51 has a slope 51a from the end 31a of the winding wire 22a of the final turn 31 of the first layer to the winding wire 22b of the first turn 32 of the second layer, and also has a surface 51b on which the winding wire 22b of the first turn 32 of the second layer is wound. In other words, the slope 51a allows the second layer winding wire 22b to be wound while smoothly climbing up the step 51, and the surface 51b allows the second layer winding wire 22b to be wound at the height of the second layer after climbing up the slope 51a of the step 51.

[0063] The second wall 42 is disposed so as to be connected to the first wall 41, and serves to guide the winding wire 22b of the first turn 32 of the second layer wound around the step 51. In other words, by guiding the winding wire 22b of the second layer wound around the step 51 with the second wall 42, the winding wire 22b of the second layer can be wound so as to be positioned next to the winding wire 22a of the final turn 31 of the first layer in plan view.

[0064] The third wall 43 is disposed to connect to the second wall 42 and guides the winding wire 22c of the second turn 33 of the second layer from the end 32a of the winding wire 22b of the first turn 32 of the second layer. The third wall 43 also guides the winding wire 22c of the second turn 33 of the second layer so that the winding wire 22c is wound adjacent to the winding wire 22b of the first turn 32 of the second layer and above the winding wire 22a of the final turn 31 of the first layer. In other words, by guiding the winding wire 22c of the second turn 33 of the second layer by the third wall 43, the second layer winding wire 22c can be wound so as to be positioned adjacent to the winding wire 22b of the first turn 32 of the second layer and directly above the winding wire 22a of the final turn 31 of the first layer in a plan view.

[0065] The cylindrical portion 12 also includes a separator 81 having a second wall 42 and a third wall 43. The separator 81 electrically insulates the primary winding 21 from the secondary winding 22. The cylindrical portion 12 includes a second cylindrical portion 12 on the step 51 side of the separator 81 and a first cylindrical portion 11 on the opposite side of the step 51. The second wall 42 is formed on a surface perpendicular to the axial direction of the cylindrical portion 12. One end 43a of the third wall 43 is connected to one end 42a of the second wall 42, and the other end 43b is located on the second cylindrical portion 12 side. In other words, the third wall 43 is inclined from the one end 43a connected to the second wall 42 toward the second cylindrical portion 12, and the other end 43b is located on the second cylindrical portion 12 side. The separator 81 also includes a fourth wall 44. One end 44a of the fourth wall 44 is connected to the other end 42b of the second wall 42, and the other end 44b is located on the second cylindrical portion 12 side and is connected to the other end 43b of the third wall 43. The second wall 43 and the fourth wall 44 form a wall that is V-shaped in plan view and bites into the second cylindrical portion 12 side. As shown in FIG. 2(B) , the winding 22 is the secondary winding 22. The primary winding 21 is wound around the first cylindrical portion 11, and the secondary winding 22 is wound around the second cylindrical portion 12. The primary winding 21 is a single wire, and the secondary winding 22 is a pair of wires, with the thickness (outer diameter) of one wire in the pair being thicker than the thickness of the primary winding 21.

[0066] In addition, in this embodiment, the winding position adjustment section 51 is formed adjacent to the separator section 81 and adjusts the winding position of the secondary winding 22, but is not limited to this and may also adjust the winding position of the primary winding 21.

[0067] Furthermore, the winding position adjusting unit 51 may adjust the winding position so as to avoid eddy current loss that occurs in the secondary winding 22 due to magnetic flux present outside the bobbin 10 .

[0068] A core hole 61 is provided inside the outer peripheral surface 12a of the cylindrical portion 12, into which a core that forms a magnetic path between the primary winding 21 and the secondary winding 22 is inserted (see FIG. 1). In other words, by providing the core hole 61 inside the outer peripheral surface 12a in this manner, a core that forms a magnetic path between the primary winding 21 and the secondary winding 22 can be inserted.

[0069] Furthermore, the annular step portion 51 preferably has a circumferential groove 51c formed along the outer peripheral surface 12a (see FIGS. 1 and 2A). This allows the circumferential groove 51c to be filled with heat-dissipating resin when potting with the resin, and the filled portion serves as a heat dissipation path, contributing to heat dissipation. In particular, when the bobbin is potted with a heat-dissipating resin having a higher thermal conductivity than the material of the bobbin and the circumferential groove 51c is filled with the resin, heat can be transferred more quickly to the heat dissipation destination, resulting in improved heat dissipation and excellent heat dissipation.

[0070] A transformer device according to one embodiment of the present invention can be realized by winding a primary winding 21 and a secondary winding 22 around the outer peripheral surfaces 11a, 12a of the first cylindrical portion 11 and the second cylindrical portion 12 of the bobbin 10, respectively, and inserting a core into the core hole 61.

[0071] According to this embodiment, in a bobbin 10 having a cylindrical portion 12 around which the winding 22 is wound in two or more layers, there is a problem that, as shown in the comparative example of FIG. 3 , the second layer of winding does not have a third wall 43 to serve as a guide, and therefore the winding tends to ride up onto the third layer, causing instability in the overlapping winding position. To address this problem, as shown in FIG. 1 , the first wall 41 guides the winding 22 a of the final turn 31 of the first layer, the winding 22 b of the first turn 32 of the second layer is wound around the annular step 51, and the third wall 43 guides the winding 22 c of the second turn 33 of the second layer from the end 32 a of the winding 22 b of the first turn 32 of the second layer. In other words, the third wall 43 is a guide provided at the winding position where the winding wire 22c of the second turn 33 in the second layer intersects with the winding wire 22b of the first turn 32 in the second layer, making it possible to guide the winding wire 22c of the second turn 33 in the second layer to the winding position and preventing the winding wire 22c of the second turn 33 in the second layer from riding up onto the third layer above the winding wire 22b of the first turn 32 in the second layer. This guide structure makes it possible to control the winding position, preventing the winding position of the second layer from becoming distorted, and stabilizing the winding position reduces variations in the winding position, contributing to stabilization of characteristics.

[0072] Furthermore, according to this embodiment, the tubular portion 12 includes a separate portion 81 having a second wall 42 and a third wall 43, and has a second tubular portion 12 on the step portion 51 side relative to the separate portion 81, and a first tubular portion 11 on the opposite side of the step portion 51. The primary winding 21 is wound around the first tubular portion 11, and the secondary winding 22 is wound around the second tubular portion 12. By making the thicknesses of the molded products of the second wall 42 and the third wall 43 uniform, and by having one end of the third wall 43 connected to the second wall 42 and the other end located on the second tubular portion 12 side, a space is created in the first tubular portion 11 on the opposite side of the third wall 43, forming an opening 71 (see FIGS. 2(A) and 2(B)). More specifically, the cylindrical portion 12 includes a separate portion 81 having a second wall 42, a third wall 43, and a fourth wall 44, and has a second cylindrical portion 12 on the step portion 51 side relative to the separate portion 81, and a first cylindrical portion 11 on the opposite side of the step portion 51. A primary winding 21 is wound around the first cylindrical portion 11, and a secondary winding 22 is wound around the second cylindrical portion 12. The thicknesses of the molded products of the second wall 42, the third wall 43, and the fourth wall 44 are made uniform, and one end 43a of the third wall 43 is connected to one end 42a of the second wall 42 and the other end 43b is located on the second cylindrical portion 12 side, while one end 44a of the fourth wall 44 is connected to the other end 42b of the second wall 42 and the other end 44b is located on the second cylindrical portion 12 side and is connected to the other end 43b of the third wall 43. This creates a space in the first cylindrical portion 11 on the side opposite the third wall 43 and the fourth wall 44, forming an opening 71 (see FIGS. 2(A) and 2(B)). When potting with heat-dissipating resin, this opening 71 serves as a resin injection inlet and can be filled with heat-dissipating resin, contributing to heat dissipation.

[0073] In this embodiment, a pair of windings is used for the secondary winding 22, but a single winding or a pair of three or more windings may be used for the secondary winding 22. Even in such cases, the same effects as those of this embodiment can be obtained.

[0074] In addition, in this embodiment, the bobbin 10 has a third wall 43 that guides the winding 22c of the second turn 33 of the second layer, but it is also possible to have a fourth wall that guides the winding of the third layer or more.

[0075] (Second Embodiment) A preferred embodiment of the present invention will be described below with reference to the drawings. Components that can be considered identical or equivalent in each drawing are designated by the same reference numerals. Furthermore, in this specification, terms describing directions such as "upper," "lower," "front," and "rear" refer to directions in a relative positional relationship in order to facilitate understanding of the invention, and are not to be construed as meaning absolute directions. Furthermore, in this specification, the term "axis" or "axial direction" refers to the bobbin winding axis (15) and its winding axis direction, unless otherwise specified.

[0076] <Bobbin and Transformer Coil> As will be described later, the transformer device 1 according to the present invention is configured to include a transformer coil 2 in which a primary winding 21 and a secondary winding 22 are wound around a bobbin 10. Here, first, an embodiment of the bobbin 10 used as the main body of such a transformer coil 2 will be described.

[0077] Fig. 4 is a perspective view of the appearance of the bobbin 10 according to one embodiment of the present invention, Fig. 5 is a top view of the bobbin 10 as viewed from the direction of arrow A in Fig. 4, and Fig. 6 is a bottom view of the bobbin 10 as viewed from the direction of arrow C in Fig. 4.

[0078] The body of the bobbin 10 is formed by arranging a first cylindrical portion 11 that forms the primary coil and a second cylindrical portion 12 that forms the secondary coil side side by side in the direction of the coil winding axis 15. The body of the bobbin 10 is integrally molded from an insulating material such as hard plastic.

[0079] A primary flange 141 is provided at one end of the first cylindrical portion 11, perpendicular to the winding shaft 15. A stand 151 is provided at the lower outer edge of the primary flange 141, and groove-shaped winding guides 161a and 161b are provided on the bracket at the upper outer edge of the primary flange 141.

[0080] A secondary flange 142 is provided at the other end of the second tubular portion 12, perpendicular to the winding shaft 15. Similar to the primary flange, a stand portion 152 is provided at the lower outer edge of the secondary flange 142, and winding guide portions 162a and 162b are provided at the upper outer edge of the secondary flange 142.

[0081] As shown in FIGS. 4 to 6, the bobbin 10 body is integrally formed with a separate portion 81 that protrudes in a flange-like shape from the connecting portion between the first cylindrical portion 11 and the second cylindrical portion 12 .

[0082] In other words, the separate portion 81 is formed as a flange portion that divides and separates the first cylindrical portion 11 and the second cylindrical portion 12 at a position closer to the first cylindrical portion 11 than approximately the center of the winding axis direction 15, or more specifically, at a position closer to the first cylindrical portion 11 than the center.

[0083] The bobbin 10 of the illustrated embodiment is characterized in that an annular step 121 that protrudes outward is formed on the outer peripheral surface 12a of the second cylindrical portion 12 at the base end on the wall surface side of the separate portion 81. Such step 121 is spaced x from the wall surface of the separate portion 81, and this spaced portion forms part of a circumferential groove 123, which will be described later. Although not illustrated, the step 121 may be provided on the outer peripheral surface 11a of the first cylindrical portion 11 so as to protrude toward the wall surface side of the separate portion 81.

[0084] The height h of this step 121 is preferably approximately the same as the wire diameter A of the winding 22. Furthermore, the maximum width W of the step 121 is preferably approximately the same as the winding width of the winding 22. Here, the "winding width" of the winding corresponds to the wire diameter A if the winding is a single-core wire, and corresponds to twice the wire diameter A if the winding is a paired wire.

[0085] In addition, it is preferable that the annular step portion 121 has a slope portion 122 whose width W gradually narrows as it approaches the vertical wall surface of the separation portion 81, as shown in FIG.

[0086] By forming such a step portion 121 in contact with the separate portion 81, the final turn portion 22' of the winding 22 of the first layer 221 wound around the second tubular portion 12 can climb onto the step portion 121 and be wound up to the height of the second layer 222, as shown in Figure 8.

[0087] This ensures that the distance between the winding 22 on the step portion 121 and the core gap portion 133 directly below the separate portion 81 is at least a certain value, thereby reducing interference between the leakage magnetic flux from the core gap portion 133 and the winding 22 (see Figure 9).

[0088] Furthermore, since the step portion 121 has the slope portion 122, the winding 22 of the final turn portion 22' can be smoothly guided onto the step portion 121 and its arrangement can be uniformly adjusted, thereby further stabilizing the inductance characteristics of the transformer device 1.

[0089] In addition, in the bobbin 10 of this embodiment, the step portion 121 preferably has a circumferential groove 123 extending along the outer periphery thereof.

[0090] This circumferential groove 123 allows the potting heat dissipation resin to stably penetrate all the way to the back (second tubular portion 12 side) of the winding 22 that has climbed onto the step 121. In addition, the penetration of the heat dissipation resin into the circumferential groove 123 forms a heat dissipation path, thereby improving the heat dissipation efficiency of the winding 22.

[0091] Furthermore, as shown in particular in Figure 6, it is preferable that the bobbin has concave lateral grooves 124, 115, 125 extending along the axial direction 15 on the outer peripheral surface 11a, 12a of at least one of the first cylindrical portion 11 or the second cylindrical portion 12.

[0092] More specifically, the step 121 preferably has a concave lateral groove 124 extending along the axial direction 15, and further, it is preferable to provide concave lateral grooves 115, 125 on the outer peripheral surfaces 11a, 12a of the first tubular portion 11 and the second tubular portion 12 located on an extension of the lateral groove 124 of the step 121. This series of lateral grooves 115, 124, 125 allows the potting heat-dissipating resin to stably penetrate all the way to the backs (second tubular portion 12 side) of the windings 21, 22 wound around the step 121 and the tubular portions 11, 12. Furthermore, the penetration of the heat-dissipating resin into the lateral grooves 115, 124, 125 forms a long heat-dissipating path, thereby further improving the heat-dissipating efficiency of the windings 21, 22.

[0093] Here, it is preferable that the bobbin 10 is formed so that at least one of the lateral groove 115 of the first tubular portion 11, the lateral groove 125 of the second tubular portion, and the lateral groove 124 of the step portion 121 is recessed inward from the outer peripheral surfaces 11a, 12a of the first tubular portion 11 and the second tubular portion 12.

[0094] In this way, by forming the lateral grooves 115, 124, 125 so as to be recessed inward from the outer peripheral surfaces 11a, 12a of the first cylindrical portion 11 and the second cylindrical portion 12, the potting heat dissipation resin can be reliably infiltrated into the lateral grooves 115, 124, 125.

[0095] FIG. 7 is a cross-sectional view of the bobbin 10 taken along line D-D in FIG. 5. In FIG. 7, the outer edge of a core 132 (described later) is indicated by a virtual line (two-dot chain line). As shown in the figure, the bobbin 10 of this embodiment has core holes 61 formed inside the outer peripheral surfaces 11a, 12a of the first cylindrical portion 11 and the second cylindrical portion 12, into which the cores 131, 132 that form a magnetic path between the primary winding 21 and the secondary winding 22 are inserted. This allows the cores 131, 132 to be inserted into the bobbin 10 through the core holes 61. The bobbin 10 also has protrusions 16A and protrusions 16B formed in the core holes 61 that form clearances 34 between the cores 131, 132 and the cores 131, 132. The protrusions 16A extend inward along the axial direction to correspond to the lateral grooves 115, 124, 125 formed on the outer peripheral surfaces 11a, 12a of the first and second cylindrical portions 11, 12, respectively, and protrude inward. The protrusions 16B extend in the axial direction parallel to the protrusions 16A on the inner peripheral surfaces 16a of the first and second cylindrical portions 11, 12. A plurality of protrusions 16B are provided on the inner peripheral surfaces 16a of the first and second cylindrical portions 11, 12, and the plurality of protrusions 16B extend in the axial direction parallel to each other on the inner peripheral surfaces 16a of the first and second cylindrical portions 11, 12. These protrusions 16A and protrusions 16B further ensure a certain or greater distance between the windings 21, 22 and the core gap portion 133. The clearance 34 between the cores 131, 132 is provided for both transformer inductance control and heat dissipation, but when the bobbin 10 body is injection molded, the above-mentioned series of lateral grooves 115, 124, 125 can also be used as a "material relief portion" provided on the opposite side of the protrusion portion 16A.

[0096] <Transformer Device> Next, a transformer device 1 using the above-described bobbin 10 will be described with reference to the schematic cross-sectional view of Fig. 9. The transformer device 1 according to this embodiment includes a transformer coil 2 formed by winding a primary winding 21 around the outer circumferential surface 11a of the first cylindrical portion 11 of the bobbin 10 and winding a secondary winding 22 around the outer circumferential surface 12a of the second cylindrical portion 12, and a pair of cores 131, 132 inserted into a core hole 61 in the body of the bobbin 10 and forming a magnetic path between the primary winding 21 and the secondary winding 22.

[0097] The cores 131 and 132 are made of a magnetic material such as ferrite. Both cores 131 and 132 have an E-shaped cross section. The core 131 is inserted through the core hole 61 on the primary side of the bobbin 10, and the core 132 is inserted through the core hole 61 on the secondary side of the bobbin 10. The tip surfaces of the cores 131 and 132 face each other with a predetermined gap between them, thereby forming a core gap 133. The core gap 133 is located at the connection between the primary coil and the secondary coil, i.e., approximately directly below the step 121 of the separator 81.

[0098] The leakage inductance of the transformer device 1 is determined by the number of turns and winding width of the primary and secondary windings 21, 22, as well as the relative positions of the windings 21, 22, the cores 131, 132, the core gap 132, etc. In the transformer device 1 of this embodiment, an annular step 121 protruding outward is formed on the wall surface side of the separator portion 81 of the bobbin 10, thereby ensuring a certain distance or more between the winding 22 on the step 121 and the core gap 133 directly below the step 121. This reduces interference between the leakage magnetic flux from the core gap 133 and the winding 22, thereby suppressing phenomena such as abnormal heating of the winding due to the influence of the leakage magnetic flux. The annular step 121 may also be referred to as a winding position adjustment portion.

[0099] In addition, in this embodiment, the winding position adjustment portion 121 is formed to protrude outward from the wall surface side of the separate portion 81 of the bobbin 10 and adjusts the winding position of the secondary winding 22, but is not limited to this and may also adjust the winding position of the primary winding 21.

[0100] Furthermore, the winding position adjusting unit 51 may adjust the winding position so as to avoid eddy current loss that occurs in the secondary winding 22 due to magnetic flux present outside the bobbin 10 .

[0101] Furthermore, a clearance 34 is formed between the cores 131, 132 and the inner circumferential surface 16a via the protrusions 16A of the first cylindrical portion 11 and the second cylindrical portion 12. By forming a clearance 34 between the cores 131, 132 and the inner circumferential surface 16a via the protrusions 16A, it is possible to infiltrate the potting heat dissipation resin into the clearance 34 and to further ensure a certain distance or more between the windings 21, 22 and the core gap portion 133.

[0102] Furthermore, since the winding positions of the windings 21 and 22 on the bobbin 10 are uniformly adjusted, it is possible to provide a transformer device 1 having leakage inductance according to the design value with little variation error between products.

[0103] Furthermore, by appropriately designing parameters such as the position, thickness, or width of the separation portion 81 in accordance with specifications such as the number of turns and winding width of the windings 21 and 22, electrical characteristics such as leakage inductance can be adjusted more precisely.

[0104] In the transformer device 1 shown in Figure 9, the outer peripheries of a pair of cores 131, 132 face each other to form a back core that encompasses the transformer coil 2, but the present invention can also be applied to transformer devices that do not have such a back core.

[0105] It should be noted that the present invention is not limited to the above-described embodiment, and various modifications and applications are possible. In other words, in the above-described embodiment, the bobbin 10 and the transformer device 1 are described, but if the bobbin 10 is included in, for example, a reactor, a choke coil, or the like, the configuration of the bobbin 10 is considered to be included in the technical scope of the claims.

[0106] REFERENCE SIGNS LIST 1 transformer device 2 transformer coil 10 bobbin 11 first cylindrical portion 11a outer circumferential surface 12 cylindrical portion (second cylindrical portion) 12a outer circumferential surface 15 winding shaft 16A protrusion 16B protrusion 16a inner circumferential surface 21 primary winding 22 winding (secondary winding) 22a final turn of winding in first layer 22b first turn of winding in second layer 22c second turn of winding in second layer 31 final turn of first layer 31a end of final turn of winding in first layer 32 first turn of second layer 32a end of first turn of winding in second layer 33 second turn of second layer 34 clearance 41 first wall 42 second wall 43 third wall 44 fourth wall 51 annular step portion 51a slope 51b Surface on which the first turn of the second layer winding is wound 51c Circumferential groove 61 Core hole 71 Opening 81 Separator portion 115 Lateral groove 121 Annular step portion 122 Slope portion 123 Circumferential groove 124, 125 Lateral grooves 131, 132 Core 133 Core gap portion 141 Primary side flange portion 142 Secondary side flange portion

Claims

1. A bobbin comprising: a separator that electrically insulates a primary winding from a secondary winding; and a winding position adjustment portion that is formed adjacent to the separator and that adjusts the winding position of at least one of the primary winding or the secondary winding.

2. A bobbin as described in claim 1, characterized in that the winding position adjustment unit adjusts the winding position so as to avoid eddy current loss generated in the primary winding or the secondary winding by magnetic flux present outside the bobbin.

3. A winding having a cylindrical portion around which at least one of the primary winding or the secondary winding is wound in two or more layers, wherein the winding position adjustment portion is an annular stepped portion with a first wall protruding like a flange from the outer peripheral surface of the cylindrical portion, and has second and third walls located on the stepped portion, wherein the first wall guides the final turn of the first layer wound around the outer peripheral surface of the cylindrical portion, the annular stepped portion is located next to the position where the final turn of the first layer is wound, has a slope from the end of the final turn of the first layer to the first turn of the second layer, and has a surface around which the first turn of the second layer is wound, the second wall guides the first turn of the second layer wound around the stepped portion, and the third wall guides the second turn of the second layer from the end of the first turn of the second layer, 2. The bobbin according to claim 1, wherein the third wall guides the second turn of the winding in the second layer so that the second turn of the winding is wound adjacent to the first turn of the winding in the second layer and above the final turn of the winding in the first layer.

4. A bobbin as described in claim 3, characterized in that the tubular portion comprises a separate portion having the second wall and the third wall, the tubular portion has a second tubular portion on the step side of the separate portion and a first tubular portion on the opposite side of the step, the second wall is formed on a surface perpendicular to the axial direction of the tubular portion, one end of the third wall is connected to the second wall and the other end is located on the second tubular portion side, the winding is a secondary winding, the first tubular portion is wound with a primary winding, and the second tubular portion is wound with the secondary winding.

5. A bobbin as described in claim 4, characterized in that a core hole is provided inside the outer circumferential surface into which a core that forms a magnetic path between the primary winding and the secondary winding is inserted.

6. The bobbin according to claim 3 or 4, wherein the step has a circumferential groove formed along the outer circumferential surface.

7. A transformer device in which a primary winding and a secondary winding are wound around the outer circumferential surfaces of the first cylindrical portion and the second cylindrical portion of the bobbin according to claim 5, and a core is inserted into the core hole.

8. A bobbin according to claim 1, in which a first cylindrical portion around which the primary winding is wound and a second cylindrical portion around which the secondary winding is wound are connected and arranged side by side in the same axial direction, wherein the outer peripheral surface of at least one of the first cylindrical portion or the second cylindrical portion has a concave horizontal groove extending along the axial direction, and the winding position adjustment portion is an annular step portion on the outer peripheral surface of at least one of the first cylindrical portion or the second cylindrical portion that protrudes outward toward the wall surface of the separate portion.

9. The bobbin according to claim 8, wherein the lateral grooves are formed so as to recess inward from the outer circumferential surface.

10. The bobbin according to claim 8, wherein a core hole is provided inside the outer circumferential surface, into which a core that constitutes a magnetic path between the primary winding and the secondary winding is inserted.

11. A bobbin as described in claim 9, wherein the core hole has a protrusion on its inner peripheral surface that extends along the axial direction and protrudes inward to correspond to a lateral groove formed inward from the outer peripheral surface.

12. The bobbin according to claim 11, characterized in that the inner peripheral surface has a plurality of protrusions extending along the axial direction in parallel with the protrusions.

13. A bobbin as described in claim 8, which is provided with a separator portion that projects like a flange from the connecting portion between the first cylindrical portion and the second cylindrical portion, thereby separating the first cylindrical portion from the second cylindrical portion.

14. The bobbin according to claim 13, wherein the step portion has a slope portion whose width gradually narrows as it approaches the wall surface of the separation portion.

15. The bobbin according to claim 13, wherein the step has a circumferential groove extending along the outer periphery thereof.

16. A transformer device comprising the primary winding and the secondary winding wound around the outer circumferential surface of the bobbin according to claim 10, and a core inserted into the core hole.

17. The transformer device according to claim 16, wherein a clearance is formed between the core and the inner peripheral surface via the protrusion.

18. A bobbin as described in claim 1, in which a first cylindrical portion around which the primary winding is wound and a second cylindrical portion around which the secondary winding is wound are connected and arranged side by side in the same axial direction, and the bobbin has a separating portion that separates the first cylindrical portion from the second cylindrical portion by protruding like a flange from the connecting portion between the first cylindrical portion and the second cylindrical portion, and the winding position adjusting portion is an annular step formed on the outer peripheral surface of at least one of the first cylindrical portion or the second cylindrical portion and protruding outward toward the wall surface of the separating portion.

19. The bobbin according to claim 18, wherein the step portion has a slope portion whose width gradually narrows as it approaches the wall surface of the separation portion.

20. The bobbin according to claim 18, wherein the step has a circumferential groove extending along the outer periphery thereof.

21. The bobbin according to claim 18, wherein the step has a transverse groove extending along the axial direction.

22. A bobbin as claimed in claim 21, wherein a lateral groove is formed along the axial direction on the outer peripheral surface of the first tubular portion and / or the second tubular portion, and the lateral groove of the first tubular portion and / or the second tubular portion is located on an extension line of the lateral groove of the step portion.

23. A bobbin as set forth in claim 22, wherein at least one of the lateral grooves of the first cylindrical portion, the lateral grooves of the second cylindrical portion, and the lateral grooves of the stepped portion is formed so as to be recessed inward from the outer circumferential surface.

24. The bobbin according to claim 18, wherein a core hole is provided inside the outer circumferential surface, into which a core that forms a magnetic path between the primary winding and the secondary winding is inserted.

25. A bobbin as set forth in claim 24, wherein the core hole has a protrusion on its inner peripheral surface that protrudes inward to correspond to a lateral groove formed inward from the outer peripheral surface.

26. A transformer device comprising a primary winding and a secondary winding wound around the outer circumferential surface of the first cylindrical portion and / or the second cylindrical portion of the bobbin according to any one of claims 18 to 25, and a core inserted into the core hole.

27. The transformer device according to claim 26, wherein a clearance is formed between the core and the inner peripheral surface via the protrusion.

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