Coil device

Abstract

To provide a coil device that prevents coil bulging and allows for miniaturization. [Solution] The coil device 1 includes a bobbin 2 having a cylindrical portion 20, a flange portion 21a protruding from the outer circumferential surface of the cylindrical portion 20, and a protrusion 28a formed at the connection between the cylindrical portion 20 and the flange portion 21a and extending along the circumferential direction of the cylindrical portion 20; a wire 3 having a coil portion 30 wound around the cylindrical portion 20 and a lead portion 31a drawn out from the coil portion 30; and a core attached to the bobbin 2. The coil portion 30 has at least a first layer 35 and a second layer arranged on the outer circumferential surface of the first layer 35 and having more layers than the first layer 35 along the axial direction of the cylindrical portion 20. The flange portion 21a has a pull-in groove 210a for drawing the wire 3 toward the cylindrical portion 20 in order to wind the wire 3 around the cylindrical portion 20. The first layer 35 has a winding start end 350 continuous with the lead portion 31a. When the retraction groove 210a is viewed from a direction perpendicular to the axial direction of the cylindrical portion 20, at least a portion of the protrusion 28a is located on the side of the retraction groove 210a where the winding start end 350 is located.

Description

Technical Field

[0001] The present disclosure relates to a coil device.

Background Art

[0002] Patent Document 1 discloses a coil device having a bobbin, a core attached to the bobbin, and a coil wound around an outer peripheral surface of the bobbin. The bobbin has a plurality of flange portions protruding from the outer peripheral surface of the bobbin. The coil is wound between one flange portion and another flange portion adjacent in the axial direction of the bobbin and has a plurality of layers (first layer to third layer) along the radial direction of the bobbin.

[0003] In the coil device of Patent Document 1, the first layer of the coil is formed by winding a wire around the outer peripheral surface of the bobbin toward one end in the axial direction of the bobbin between one flange portion and another flange portion adjacent thereto. Next, the second layer of the coil is formed by winding the wire around the outer peripheral surface of the first layer toward the other end in the axial direction of the bobbin. Next, the third layer of the coil is formed by winding the wire around the outer peripheral surface of the second layer toward one end in the axial direction of the bobbin.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, depending on the type of wire, it is difficult to wind the wire neatly around the outer peripheral surface of the bobbin, and the shape of the first layer of the coil may become unstable. In such a state, when forming the second and subsequent layers of the coil, the coil bulges, making it difficult to miniaturize the coil device.

[0006] This disclosure provides a coil device that can prevent coil bulging and achieve miniaturization. [Means for solving the problem]

[0007] The coil device of this disclosure is A bobbin having a cylindrical portion, a flange portion protruding from the outer circumferential surface of the cylindrical portion, and a convex portion formed at the connection between the cylindrical portion and the flange portion and extending along the circumferential direction of the cylindrical portion, A wire having a coil portion wound around the cylindrical portion and a lead portion drawn out from the coil portion, The bobbin has a core attached to it, The coil portion comprises at least a first layer and a second layer arranged on the outer circumferential surface of the first layer and having more layers than the first layer along the axial direction of the cylindrical portion. The flange portion has a pull-in groove for pulling the wire toward the cylindrical portion in order to wind the wire around the cylindrical portion. The first layer has a winding start end that is continuous with the draw-out portion, When the retraction groove is viewed from a direction perpendicular to the axial direction, at least a portion of the protrusion is located on the side of the retraction groove where the winding start end is located. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a perspective view of the coil device of this disclosure. [Figure 2] Figure 2 is an exploded perspective view of the coil device shown in Figure 1. [Figure 3] Figure 3 is a perspective view of the bobbin shown in Figure 2. [Figure 4] Figure 4 is a perspective view of the bobbin shown in Figure 2, viewed from a different angle. [Figure 5] Figure 5 is a perspective view of the bobbin shown in Figure 2, viewed from a different angle. [Figure 6] Figure 6 is a cross-sectional view along the line VI-VI shown in Figure 1. [Figure 7] Figure 7 is a diagram illustrating a method for forming the first layer of the coil portion on the outer surface of the bobbin shown in Figure 2. [Modes for carrying out the invention]

[0009] The embodiments of this disclosure will be described below with reference to the drawings. Note that the illustrations are provided for illustrative purposes only to aid in understanding this disclosure, and the appearance and dimensional ratios may differ from those of the actual product. Furthermore, this disclosure is not limited to the embodiments described below.

[0010] The coil device 1 of one embodiment of the present disclosure shown in Figure 1 functions, for example, as a transformer and is mounted in the power supply circuit of an electrical device. As shown in Figure 2, the coil device 1 has at least a bobbin 2, wires 3 and 4, and cores 5a to 5d. In addition to these components, the coil device 1 of this embodiment further has heat dissipation members 6a to 6b and terminals 7a to 7d. However, these components are not essential and may be omitted from the coil device 1.

[0011] Cores 5a to 5d are attached to bobbin 2. Cores 5a to 5d are formed from a material containing a magnetic material and a resin. The magnetic material constituting cores 5a to 5d is not particularly limited, but may be, for example, ferrite (Ni-Zn ferrite, Mn-Zn ferrite, etc.) or metallic magnetic material (Fe-Ni alloy, Fe-Si alloy, Fe-Si-Cr alloy, Fe-Co alloy, Fe-Si-Al alloy, amorphous iron, etc.). The resin constituting cores 5a to 5d is not particularly limited, but may be epoxy resin, phenolic resin, polyester resin, polyurethane resin, polyimide resin, etc. Cores 5a to 5d may also be sintered bodies of metallic magnetic material.

[0012] Each of the cores 5a to 5d has a base portion 50, an outer leg portion 51, and a middle leg portion 52. The cores 5a to 5d have the same shape, but may have different shapes. In the following, the axis along the direction in which core 5a and core 5b face each other will be defined as the Y-axis. The axis along the direction in which core 5a and core 5c face each other will be defined as the Z-axis. The axis perpendicular to the Y-axis and Z-axis will be defined as the X-axis. The X-axis, Y-axis, and Z-axis are perpendicular to each other.

[0013] In the present disclosure, the positive direction side of the Z-axis is defined as "upward", and the negative direction side of the Z-axis is defined as "downward". However, the upward direction in the Z-axis direction does not necessarily coincide with the upward direction in the vertical direction. Also, the downward direction in the Z-axis direction does not necessarily coincide with the downward direction in the vertical direction.

[0014] The outer leg portion 51 protrudes from the base portion 50 and is disposed around the coil portion 30 or 40. The inner peripheral surface of the outer leg portion is curved along the outer peripheral surface of the middle leg portion 52.

[0015] The middle leg portion 52 protrudes from the base portion 50 and is disposed inside the cylindrical portion 20 of the bobbin 2. The cross-sectional shape (a cross-section perpendicular to the Z-axis) of the middle leg portion 52 is semi-elliptical, but it may also be semi-circular, square, rectangular, other polygons, or other shapes. The middle leg portion 52 of the core 5a faces the middle leg portion 52 of the core 5b. The middle leg portion 52 of the core 5c faces the middle leg portion 52 of the core 5d. Between the middle leg portion 52 of the core 5a and the middle leg portion 52 of the core 5b, the inner side portions 62 of the heat dissipation members 6a and 6b are disposed. Also, between the middle leg portion 52 of the core 5c and the middle leg portion 52 of the core 5d, the inner side portions 62 of the heat dissipation members 6a and 6b are disposed.

[0016] Note that the number and shape of the cores are not particularly limited. For example, the coil device 1 may have two E-shaped cores that can be combined in the vertical direction. Alternatively, the coil device 1 may have one E-shaped core and one I-shaped core that can be combined in the vertical direction. Alternatively, the coil device 1 may have a plurality of I-shaped cores and / or U-shaped cores that can be combined with each other.

[0017] In the state where the cores 5a and 5c are attached to the bobbin 2, the tip of the outer leg portion 51 of the core 5a may contact the tip of the outer leg portion 51 of the core 5c. Alternatively, the tip of the outer leg portion 51 of the core 5a may be separated from the tip of the outer leg portion 51 of the core 5c. Further, in the state where the cores 5b and 5d are attached to the bobbin 2, the tip of the outer leg portion 51 of the core 5b may contact the tip of the outer leg portion 51 of the core 5d. Alternatively, the tip of the outer leg portion 51 of the core 5b may be separated from the tip of the outer leg portion 51 of the core 5d.

[0018] Also, in the state where the cores 5a to 5d are attached to the bobbin 2, each middle leg portion 52 of the cores 5a and 5b may contact the tip of each middle leg portion 52 of the cores 5c and 5d. Alternatively, the tip of each middle leg portion 52 of the cores 5a and 5b may be separated from the tip of each middle leg portion 52 of the cores 5c and 5d.

[0019] The wires 3 and 4 are, for example, insulated coated wires. The wires 3 and 4 are known windings such as AIW (polyamideimide copper wire), UEW (polyurethane copper wire), PEW (polyester copper wire), etc. The wires 3 and 4 are litz wires, but may also be round wires, square wires, stranded wires, braided wires, etc. The material constituting the core wire of the wires 3 and 4 is not particularly limited, but is, for example, copper, copper alloy, silver or nickel. The diameter of the wire 3 or 4 is not particularly limited, but is, for example, 0.5 to 5 μm. The diameter of the wire 3 may be equal to or different from the diameter of the wire 4.

[0020] In the present disclosure, "equal" or "equivalent" does not refer to the concept that only indicates the state where the physical quantities of a plurality of objects to be compared are exactly equal, but also includes the state where an error of ±Δ% (not particularly limited, for example, Δ = 7, 5 or 3) or less occurs between the physical quantities of the plurality of objects to be compared in the concept of "equal" or "equivalent".

[0021] The wire 3 has a winding section 30 and lead-out sections 31a to 31b drawn out from the winding section 30. The winding section 30 is wound directly or indirectly around the outer circumferential surface of the cylindrical section 20 of the bobbin 2. The winding axis direction of the winding section 30 corresponds to the Z axis direction. Lead-out section 31a is one end of the wire 3, and lead-out section 31b is the other end of the wire 3.

[0022] The wire 4 has a winding section 40 and lead-out sections 41a to 41b drawn out from the winding section 40. The winding section 40 is wound directly or indirectly around the outer circumferential surface of the cylindrical section 20 of the bobbin 2. The winding axis direction of the winding section 40 corresponds to the Z axis direction. One of the coil sections 30 and 40 functions as a primary coil, and the other functions as a secondary coil. Lead-out section 41a is one end of the wire 4, and lead-out section 41b is the other end of the wire 4.

[0023] As shown in Figure 1, terminals 7b and 7a are attached to the drawer sections 31a and 31b, respectively. Terminals 7d and 7c are attached to the drawer sections 41a and 41b, respectively.

[0024] As shown in Figure 6, the coil section 30 has at least a first layer 35 and a second layer 36. That is, the coil section 30 has multiple layers in a direction perpendicular to the axial direction of the bobbin 2. In this embodiment, the coil section 30 further has a third layer 37 and a fourth layer 38, but the number of layers in the coil section 30 may be two, three, or five or more.

[0025] The first layer 35 is located on the outer circumferential surface of the cylindrical portion 20 of the bobbin 2 and consists of four layers along the axial direction (Z-axis direction) of the cylindrical portion 20. The second layer 36 is located on the outer circumferential surface of the first layer 35 and has more layers (5 layers) than the first layer 35 along the axial direction of the cylindrical portion 20. The third layer 37 is located on the outer circumferential surface of the second layer 36 and has fewer layers than the second layer 36 (the same number of layers as the first layer 35) along the axial direction of the cylindrical portion 20. The fourth layer 38 is located on the outer circumferential surface of the third layer 37 and has more layers than the third layer 37 (the same number of layers as the second layer 36) along the axial direction of the cylindrical portion 20. The number of layers of the first layer 35, second layer 36, third layer 37 and / or fourth layer 38 along the axial direction of the cylindrical portion 20 is not limited to the number of layers shown in Figure 6.

[0026] As shown in Figure 7, the first layer 35 has a winding start end 350 that is continuous with the lead-out portion 31a. The winding start end 350 is the end of the first layer 35 on the winding start side, and the wire 3 is wound around the outer circumferential surface of the cylindrical portion 20 starting from the winding start end 350. When forming the first layer 35 on the outer circumferential surface of the cylindrical portion 20, the wire 3 is wound starting from a position adjacent to the flange portion 21a (thickened portion 280 of the protrusion 28a). Therefore, the winding start end 350 is located adjacent to the flange portion 21a (thickened portion 280 of the protrusion 28a). When forming the first layer 35 on the outer circumferential surface of the cylindrical portion 20, the wire 3 is pulled out diagonally toward the leg portion 26a, as shown by the solid line. However, as shown by the dashed line, after the first layer 35 is formed, the wire 3 is pulled out toward the terminal block 25 (Figure 3) located above the cylindrical portion 20.

[0027] As shown in Figure 6, the coil section 40 has at least a first layer 45 and a second layer 46. That is, the coil section 40 has multiple layers in a direction perpendicular to the axial direction of the bobbin 2. In this embodiment, the coil section 40 further has a third layer 47 and a fourth layer 48, but the number of layers in the coil section 40 may be two, three, or five or more.

[0028] The first layer 45 is located on the outer circumferential surface of the cylindrical portion 20 of the bobbin 2 and consists of four layers along the axial direction (Z-axis direction) of the cylindrical portion 20. The second layer 46 is located on the outer circumferential surface of the first layer 45 and has more layers (5 layers) than the first layer 45 along the axial direction of the cylindrical portion 20. The third layer 47 is located on the outer circumferential surface of the second layer 46 and has fewer layers than the second layer 46 (the same number of layers as the first layer 45) along the axial direction of the cylindrical portion 20. The fourth layer 48 is located on the outer circumferential surface of the third layer 47 and has more layers than the third layer 47 (the same number of layers as the second layer 46) along the axial direction of the cylindrical portion 20. The number of layers of the first layer 45, second layer 46, third layer 47 and / or fourth layer 48 along the axial direction of the cylindrical portion 20 is not limited to the number of layers shown in Figure 6.

[0029] As shown in Figure 2, each of the terminals 7a to 7d has a connecting portion 70, a mounting portion 71, and a clamping portion 72. The connecting portion 71 is the part that connects to the mounting board (not shown). The mounting portion 71 protrudes perpendicular to the connecting portion 70 and is fitted into the hole 252 of the terminal block 25 of the bobbin 2. The clamping portion 72 is configured to be flexible and clamps the lead-out portions 31a, 31b, 41a, or 41b.

[0030] In this disclosure, "perpendicular" does not refer only to strictly perpendicular lines, but also includes a state in which there is an error of ±Δθ° (not particularly limited, but for example, Δθ=3) or less from strictly perpendicular lines. Similarly, "parallel" does not refer only to strictly parallel lines, but also includes a state in which there is an error of ±Δθ° (not particularly limited, but for example, Δθ=3) or less from strictly parallel lines.

[0031] The heat dissipation members 6a and 6b are composed of flat, plate-shaped members. The materials that make up the heat dissipation members 6a and 6b are not particularly limited, but are metals such as aluminum, copper, and silver. Each of the heat dissipation members 6a and 6b has a top portion 60, an outer portion 61, and an inner portion 62.

[0032] As shown in Figure 6, the top portion 60 of the heat dissipation member 6a is positioned on the base portion 50 of the core 5a, and the top portion 60 of the heat dissipation member 6b is positioned on the base portion 50 of the core 5b. The outer portion 61 of the heat dissipation member 6a is positioned on the outer circumferential surface of the outer leg portions 51 of the cores 5a and 5c, and the outer portion 61 of the heat dissipation member 6b is positioned on the outer circumferential surface of the outer leg portions 51 of the cores 5b and 5d. The outer portion 61 is spaced apart from the outer circumferential surface of the outer leg portions 51, but may be in contact with the outer circumferential surface of the outer leg portions 51. The inner portion 62 of the heat dissipation member 6a is positioned between the middle leg portion 52 of the core 5a and the middle leg portion 52 of the core 5b, and further between the middle leg portion 52 of the core 5c and the middle leg portion 52 of the core 5d. Furthermore, the inner portion 62 of the heat dissipation member 6b is positioned between the middle leg portion 52 of core 5a and the middle leg portion 52 of core 5b, and also between the middle leg portion 52 of core 5c and the middle leg portion 52 of core 5d.

[0033] As shown in Figure 3, the bobbin 2 is made of a plastic such as PPS, PET, PBT, or LCP, or other insulating material. The bobbin 2 has at least a cylindrical portion 20, flange portions 21a to 21c, and protrusions 28a to 28b. In addition to these components, the bobbin 2 further has core fixing portions 22 to 23, a partition 24, a terminal block 25, leg portions 26a to 26d, and a connecting passage 27. However, these components are not essential and may be omitted from the coil device 1.

[0034] The cylindrical portion 20 is a cylindrical body having a through hole 200. The through hole 200 extends along the axial direction of the cylindrical portion 20. The cylindrical portion 20 has a flow hole that penetrates the cylindrical portion 20 from the outer circumferential surface to the inner circumferential surface. For example, when a bobbin 2 or the like is housed in a case (not shown) and a heat-dissipating resin (not shown) is filled inside the case, the heat-dissipating resin flows into the interior of the cylindrical portion 20 through the flow hole. The plan view shape of the cylindrical portion 20 is an ellipse with its longer side in the X-axis direction, but it may be a circle, a quadrilateral, another polygon, or any other shape.

[0035] The flanges 21a to 21c protrude from the outer circumferential surface of the cylindrical portion 20 in a direction perpendicular to the axial direction of the cylindrical portion 20. Flange 21a faces flange 21b along the axial direction of the cylindrical portion 20. Flange 21b faces flange 21c along the axial direction of the cylindrical portion 20. Flange 21a is located at the lower end of the cylindrical portion 20, flange 21c is located at the upper end of the cylindrical portion 20, and flange 21b is located between flanges 21a and 21c. As shown in Figure 6, a coil portion 30 is wound between flanges 21a and 21b, and a coil portion 40 is wound between flanges 21b and 21c.

[0036] As shown in Figure 3, the flange portion 21a has retraction grooves 210a to 210b and a chamfered portion 211. As shown in Figure 7, the retraction groove 210a constitutes a passage for pulling the wire 3 toward the cylindrical portion 20 in order to wind the wire 3 around the cylindrical portion 20 when forming the first layer 35 on the outer surface of the cylindrical portion 20. Note that in Figure 7, only the first layer 35 wound around the outer surface of the cylindrical portion 20 is shown, and the second layer 36, third layer 37 and fourth layer 38 are omitted from the illustration.

[0037] As shown in Figures 3 and 5, the retraction groove 210a is located at one end of the flange portion 21a in the X-axis direction, and the retraction groove 210b is located at the other end of the flange portion 21a in the X-axis direction. The retraction grooves 210a and 210b are formed in the flange portion 21a so as to cut out the flange portion 21a from the outer edge of the flange portion 21a toward the outer circumferential surface of the cylindrical portion 20. Note that the flange portion 21a may have the retraction groove 210a but not the retraction groove 210b.

[0038] The chamfered portion 211 is formed along the recessed groove 210a. The chamfered portion 211 chamfers at least a portion of the ridge located between the flange portion 21a and the leg portion 26b, forming a chamfered C-face.

[0039] The flange portion 21b has a pull-in groove 210c and a wire engagement portion 212. The pull-in groove 210c constitutes a passage for pulling the wire 4 toward the cylindrical portion 20 in order to wind the wire 4 around the cylindrical portion 20 when forming the first layer 45 (Figure 6) on the outer surface of the cylindrical portion 20. As shown in Figure 2, the lead-out portion 31b, which is pulled out from the coil portion 30 toward the terminal block 25, can be engaged with the wire engagement portion 212.

[0040] As shown in Figure 3, the core fixing portions 22 and 23 protrude upward from the upper surface of the flange portion 21c. The core fixing portion 22 is located on one side of the flange portion 21c in the X-axis direction, and the core fixing portion 23 is located on the other side of the flange portion 21c in the X-axis direction. The core fixing portions 22 and 23 are bent in a V-shape along the shape of the base portion 50 of the cores 5a and 5b shown in Figure 2.

[0041] As shown in Figure 3, the partition 24 is formed on the inner circumferential surface of the cylindrical portion 20 and is located at one end of the cylindrical portion 20 in the X-axis direction. Although not shown in detail, the partition 24 is also formed at the other end of the cylindrical portion 20 in the X-axis direction. The pair of partitions 24 are located between the middle leg portion 52 of core 5a and the middle leg portion 52 of core 5b shown in Figure 2, forming a gap between these middle leg portions 52 for arranging the inner portions 62 of heat dissipation members 6a and 6b. The pair of partitions 24 are also located between the middle leg portion 52 of core 5c and the middle leg portion 52 of core 5d shown in Figure 2, forming a gap between these middle leg portions 52 for arranging the inner portions 62 of heat dissipation members 6a and 6b.

[0042] As shown in Figure 3, the terminal block 25 is formed at the X-axis end of the flange portion 21c. The terminal block 25 has a body 250, a plurality (eight in this embodiment) of holes 251, and a plurality (three in this embodiment) of protrusions 252. The shape of the body 250 is not particularly limited, but it is elongated in the Y-axis direction. The plurality of holes 251 are formed on the side surface of the body 250, spaced apart along the Y-axis. A pair of mounting portions 71 of any of the terminals 7a to 7d shown in Figure 2 are fitted into a pair of holes 251. The plurality of protrusions 252 are formed on the side surface of the body 250, spaced apart along the Y-axis. Any of the plurality of protrusions 252 are positioned between terminals 7a and 7b, between terminals 7b and 7c, or between terminals 7c and 7d.

[0043] As shown in Figures 4 and 5, the legs 26a to 26d protrude downward from the flange 21a along the axial direction of the cylindrical portion 20. Leg 26a extends along the outer edge of the flange 21a. On the other hand, leg 26b extends along the outer edge of the flange 21a and also along the retraction groove 210a. Legs 26c and 26d also extend along the outer edge of the flange 21a and also along the retraction groove 210b. Legs 26b to 26d are bent in a V-shape along the shape of the base portion 50 of the cores 5c and 5d shown in Figure 2. Legs 26a to 26d serve to prevent rotation of the cores 5a to 5d around the Z-axis.

[0044] The connecting passage 27 is provided between the cylindrical portion 20 and the leg portion 26a. As shown in Figure 7, the connecting passage 27 constitutes a passage that guides the wire 3 toward the cylindrical portion 20 in order to wind the wire 3 around the cylindrical portion 20 when forming the first layer 35 on the outer surface of the cylindrical portion 20. The wire 3 passing through the connecting passage 27 may engage with the leg portion 26a.

[0045] As shown in Figure 3, the protrusion 28a is formed at the connection point between the cylindrical portion 20 and the flange portion 21a and extends along the circumferential direction of the cylindrical portion 20. Similarly, the protrusion 28b is formed at the connection point between the cylindrical portion 20 and the flange portion 21b and extends along the circumferential direction of the cylindrical portion 20. The protrusions 28a and 28b project from the outer circumferential surface of the cylindrical portion 20 in a direction perpendicular to the axial direction of the cylindrical portion 20, and project from the main surfaces of the flange portions 21a and 21b, respectively, along the axial direction of the cylindrical portion 20.

[0046] As shown in Figure 7, when the retraction groove 210a is viewed from a direction perpendicular to the axial direction of the cylindrical portion 20, at least a portion (all in this embodiment) of the protrusion 28a is located on the side of the retraction groove 210a where the winding start end 350 is located (i.e., on the negative Y-axis side with respect to the retraction groove 210a). Although detailed illustration is omitted, when the retraction groove 210b is viewed from a direction perpendicular to the axial direction of the cylindrical portion 20, at least a portion (all in this embodiment) of the protrusion 28b is located on the side of the retraction groove 210b where the winding start end of the wire 4 (Figure 2) is located (i.e., on the negative Y-axis side with respect to the retraction groove 210b).

[0047] As shown in Figures 4 and 5, the protrusions 28a and 28b have similar configurations. Therefore, a detailed explanation of the protrusion 28b will be omitted below. The protrusion 28a has a thick-walled portion 280 having a relatively thicker thickness along the axial direction of the cylindrical portion 20, and a thin-walled portion 281 having a relatively thinner thickness along the axial direction of the cylindrical portion 20. In this embodiment, the protrusion 28a has a thick-walled portion 280 and a thin-walled portion 281, but the protrusion 28a may have only a thick-walled portion 280.

[0048] The thickened portion 280 is configured separately from the thinned portion 281, but may be configured as an integral part. For example, the thickened portion 280 may be continuously connected to the thinned portion 281 on the side where the recessed groove 210b is located. In this case, the protrusion 28a is composed of a single protrusion. However, the thickened portion 280 is not continuously connected to the thinned portion 281 on the side where the recessed groove 210a is located, but is separated from the thinned portion 281. The thickened portion 280 is composed of a single continuously extending protrusion, but may be composed of multiple intermittently extending protrusions. Similarly, the thinned portion 281 is composed of a single continuously extending protrusion, but may be composed of multiple intermittently extending protrusions.

[0049] The length of the protruding portion 28a in the extending direction (the sum of the lengths of the thickened portion 280 and the thinned portion 281 in the extending direction) is not particularly limited, but is, for example, 50% or more of the length of the outer circumference of the cylindrical portion 20. The length of the thickened portion 280 in the extending direction is not particularly limited, but is, for example, 50% or less of the length of the outer circumference of the cylindrical portion 20. The length of the thinned portion 281 in the extending direction is not particularly limited, but is, for example, 50% or less of the length of the outer circumference of the cylindrical portion 20.

[0050] As shown in Figure 6, the thickness T1 of the walled portion 280 in the direction perpendicular to the Z-axis is not particularly limited, but is, for example, equal to or less than the diameter of the wire 3. Also, the thickness T1 of the walled portion 280 in the direction perpendicular to the Z-axis is not particularly limited, but is, for example, 1 / 3 or 1 / 2 or more of the diameter of the wire 3.

[0051] The thickness T2 of the thickened portion 280 in the Z-axis direction is not particularly limited, but is, for example, equal to or less than the diameter of the wire 3. Also, the thickness T2 of the thickened portion 280 in the Z-axis direction is not particularly limited, but is, for example, 1 / 3 or 1 / 2 or more of the diameter of the wire 3.

[0052] The thickness T3 of the thin-walled portion 281 in the direction perpendicular to the Z-axis is not particularly limited, but is, for example, equal to or less than the diameter of the wire 3. In this embodiment, the thickness T3 of the thin-walled portion 281 in the direction perpendicular to the Z-axis is equal to the thickness T1 of the thick-walled portion 280 in the direction perpendicular to the Z-axis, but may be different. Also, the thickness T3 of the thin-walled portion 281 in the direction perpendicular to the Z-axis is not particularly limited, but is, for example, 1 / 3 or 1 / 2 or more of the diameter of the wire 3.

[0053] The thickness T4 in the Z-axis direction of the thin-walled portion 281 is thinner than the thickness T2 in the Z-axis direction of the thick-walled portion 280, and is not particularly limited, but is between 1 / 5 and 4 / 5 of the thickness T2, or between 1 / 4 and 3 / 4 of the thickness T2. Also, the thickness T4 in the Z-axis direction of the thin-walled portion 281 is not particularly limited, but is, for example, less than 1 / 2 of the diameter of the wire 3. Also, the thickness T4 in the Z-axis direction of the thin-walled portion 281 is not particularly limited, but is, for example, 1 / 10 or more of the diameter of the wire 3.

[0054] As shown in Figure 7, when the retraction groove 210a is viewed from a direction perpendicular to the axial direction of the cylindrical portion 20, at least a portion (in this embodiment, all) of the thick portion 280 is located on one side of the retraction groove 210a (the negative Y-axis side, or the side where the winding start end 350 is located), and at least a portion (in this embodiment, all) of the thin portion 281 is located on the other side of the retraction groove 210a (the positive Y-axis side).

[0055] Furthermore, a portion of the thickened portion 280 may be located on the other side (positive Y-axis side) relative to the recessed groove 210a. Also, a portion of the thinned portion 281 may be located on one side (negative Y-axis side) relative to the recessed groove 210a.

[0056] The protrusion 28 has an inclined portion 282 that slopes toward one end in the direction of extension of the protrusion 28. When the pull-in groove 210a is viewed from a direction perpendicular to the axial direction of the cylindrical portion 20, the inclined portion 282 is located on the side (negative Y-axis direction) where the winding start end 350 is located relative to the pull-in groove 210a. The thickness of the protrusion 28 along the axial direction of the cylindrical portion 20 becomes thinner as it approaches the pull-in groove 210a. When forming the first layer 35 on the outer circumferential surface of the cylindrical portion 20, the wire 3 can be pulled out along the inclined portion 282.

[0057] The inclined portion 282 is formed in the thickened portion 280 and is inclined toward one end of the thickened portion 280 in the extending direction. In the example shown in Figures 4 and 5, two inclined portions 282 are formed at one end and the other end of the thickened portion 280 in the extending direction. However, there may be only one inclined portion 282. For example, one inclined portion 282 may be located on the side where the pull-in groove 210a is located, or on the side where the winding start end 350 of the wire 3 (Figure 7) is located. In addition to the thickened portion 280, the inclined portion 282 may also be formed in the thinned portion 281. The inclined portion 282 is spaced apart from the chamfered portion 211, but may be continuously connected to the chamfered portion 211.

[0058] As shown in Figure 6, the first layer 35 is in contact with the convex portion 28a (thick portion 280 and thin portion 281) while being separated from the flange portion 21b. More specifically, the first turn 351 of the first layer 35 is in contact with the convex portion 28a, and the fourth turn 352 of the first layer 35 is separated from the flange portion 21b. Therefore, a gap 8 is formed between the first layer 35 and the flange portion 21b. The length of the gap 8 in the Z-axis direction is not particularly limited, but for example, it is equal to or less than the diameter of the wire 3, or less than or equal to half the diameter of the wire 3.

[0059] At least a portion of the first turn 361 of the second layer 36 fits into the recess between the fourth turn 352 of the first layer 35 and the flange 21b. Therefore, at least a portion of the gap 8 is covered by the first turn 361 of the second layer 36. The first turn 361 of the second layer 36 may be in contact with the flange 21b or may be spaced apart from the flange 21b.

[0060] The fifth turn 362 of the second layer 36 is positioned on the protrusion 28a and / or the first turn 351 of the first layer 35. More specifically, at least a portion of the fifth turn 362 fits into the recess between the protrusion 28a and the first turn 351. Alternatively, at least a portion of the fifth turn 362 fits into the recess between the first turn 351 and the flange 21a. At least a portion of any turn of the second layer 36 (other than the first turn 361 and the fifth turn 362) fits into the recess between any two adjacent turns of the first layer 35.

[0061] The third layer 37 is spaced apart from the flanges 21a and 21b. The fourth layer 38 is in contact with the flanges 21a and / or 21b, but may be spaced apart from them.

[0062] In this embodiment, when the number of layers of the second layer 36 along the axial direction of the cylindrical portion 20 is n, the diameter of the wire 3 is d, and the distance along the axial direction of the cylindrical portion 20 from flange portion 21a to flange portion 21b is D, the number of layers is d × n, although this is not particularly limited. <D≦d×(n+1)である。

[0063] Next, the manufacturing method of the coil device 1 will be described. First, terminals 7a to 7d are attached to the terminal block 25 of the bobbin 2 shown in Figure 2. Terminals 7a to 7d may be integrally molded with the terminal block 25. Next, wire 3 is wound around the outer surface of the cylindrical portion 20 of the bobbin 2 to form a coil portion 30, and wire 4 is wound around to form a coil portion 40.

[0064] As shown in Figure 7, in forming the first layer 35 of the coil portion 30, the wire 3 is passed through the communication passage 27 and pulled out diagonally toward the convex portion 28a along the chamfered portion 211 and the inclined portion 282 of the convex portion 28a. Then, the wire 3 is wound around the outer surface of the cylindrical portion 20 in four layers in the direction from the flange portion 21a toward the flange portion 21b to form the first layer 35. Furthermore, as shown in Figure 6, the wire 3 is wound around the outer surface of the first layer 35 in five layers in the direction from the flange portion 21b toward the flange portion 21a to form the second layer 36. Furthermore, the wire 3 is wound around the outer surface of the second layer 36 in four layers in the direction from the flange portion 21a toward the flange portion 21b to form the third layer 37. Furthermore, the wire 3 is wound around the outer surface of the third layer 37 in five layers in the direction from the flange portion 21b toward the flange portion 21a to form the fourth layer 38. The coil portion 30 is formed in the manner described above. The coil portion 40 is formed in the same manner as the coil portion 30.

[0065] Next, as shown by the dashed line in Figure 7, one end of wire 3 (outlet 31a) is moved to the outside of the connecting passage 27 and pulled out toward the terminal block 25 shown in Figure 2. Then, one end of wire 3 (outlet 31a) is connected to terminal 7b. Also, as shown in Figure 2, the other end of wire 3 (outlet 31b) is pulled out toward the terminal block 25 and connected to terminal 7a. Furthermore, one end of wire 4 (outlet 41a) is pulled out toward the terminal block 25 and connected to terminal 7d. Also, the other end of wire 4 (outlet 41b) is pulled out toward the terminal block 25 and connected to terminal 7c.

[0066] Next, cores 5a to 5d are attached to the bobbin 2. Then, heat dissipation member 6a is attached to cores 5a and 5c, and heat dissipation member 6b is attached to cores 5b and 5d. If necessary, the bobbin 2 and other components may be housed in a case, and the inside of the case may be filled with heat dissipation resin. In this way, the coil device 1 can be manufactured.

[0067] As shown in Figure 7, in the coil device 1 of this embodiment, when the pull-in groove 210a is viewed from a direction perpendicular to the axial direction of the cylindrical portion 20, at least a part of the protrusion 28a is located on the side where the winding start end 350 is located relative to the pull-in groove 210a. Therefore, when forming the first layer 35 on the outer circumferential surface of the cylindrical portion 20, the wire 3 is started to be wound along the protrusion 28a. By starting to wind the wire 3 along the protrusion 28a, it becomes easier to wind the wire 3 neatly around the outer circumferential surface of the cylindrical portion 20, and the shape of the first layer 35 is stabilized. Furthermore, by winding the wire 3 around the outer circumferential surface of the first layer 35 after stabilizing its shape, the shape of the second layer 36 (Figure 6) is stabilized, and the coil portion 30 is less likely to bulge. This makes it possible to miniaturize the coil device 1.

[0068] Furthermore, the protrusion 28a has a thick-walled portion 280 having a relatively thicker thickness along the axial direction of the cylindrical portion 20, and a thin-walled portion 281 having a relatively thinner thickness along the axial direction of the cylindrical portion 20. Therefore, when forming the first layer 35 on the outer circumferential surface of the cylindrical portion 20, the wire 3 is wound around the outer circumferential surface of the cylindrical portion 20 along the thick-walled portion 280 and the thin-walled portion 281. This makes it easier to form a space at the end of the winding of the first layer 35 corresponding to the difference in thickness between the thick-walled portion 280 and the thin-walled portion 281. Therefore, when moving the wire 3 from the first layer 35 to the second layer 36, it becomes easier to position the first turn 361 (Figure 6) of the second layer 36 on the outer circumferential surface of the first layer 35. As a result, the shape of the second layer 36 becomes stable, and the coil portion 1 is less likely to bulge.

[0069] Furthermore, when viewing the pull-in groove 210a from a direction perpendicular to the axial direction of the cylindrical portion 20, at least a portion of the thick portion 280 is located on one side (negative Y-axis direction) relative to the pull-in groove 210a, and at least a portion of the thin portion 281 is located on the other side (positive Y-axis direction) relative to the pull-in groove 210a. Therefore, when forming the first layer 35 on the outer surface of the cylindrical portion 20, the wire 3 is started to be wound along the thick portion 280. By starting to wind the wire 3 along the thick portion 280, a space corresponding to the difference in thickness between the thick portion 280 and the thin portion 281 is easily formed at the end of the winding of the first layer 35, and the wire 3 can be smoothly transferred from the first layer 35 to the second layer 36.

[0070] Furthermore, the thick portion 280 is separate from the thin portion 281. By separating the thick portion 280 and the thin portion 281, a space is more easily formed at the end of the winding of the first layer 35, making it easier to form the first layer 35.

[0071] Furthermore, the protrusion 28a has an inclined portion 282 that slopes toward one end in the direction of extension of the protrusion 28a. In the inclined portion 282, the thickness of the protrusion 28a along the axial direction of the cylindrical portion 20 becomes thinner as it approaches the pull-in groove 210a. Therefore, when forming the first layer 35 on the outer surface of the cylindrical portion 20, the wire 3 can be pulled out diagonally along the inclined portion 282. This makes it possible to pull out the wire 3 to the protrusion 28a without excessive bending of the wire 3, and makes it easier to wind the wire 3 along the protrusion 28a, especially when the diameter of the wire 3 is large.

[0072] Furthermore, the inclined portion 282 is formed in the thickened portion 280 and is inclined toward one end in the extending direction of the thickened portion 280. Therefore, it is possible to achieve both the aforementioned effects, namely, the effect of making it easier to wind the wire 3 along the convex portion 28a and the effect of smoothly transferring the wire 3 from the first layer 35 to the second layer 36.

[0073] Furthermore, when the pull-in groove 210a is viewed from a direction perpendicular to the axial direction of the cylindrical portion 20, the inclined portion 282 is located on the side of the pull-in groove 210a where the winding start end 350 is located. Therefore, when forming the first layer 35 on the outer surface of the cylindrical portion 20, the wire 3 is started to be wound along the inclined portion 282. This makes it easier to stabilize the shape of the first turn of the first layer 35 in particular.

[0074] Furthermore, the flange portion 21a has a chamfered portion 211 formed along the retraction groove 210a. Therefore, when forming the first layer 35 on the outer surface of the cylindrical portion 20, the wire 3 can be pulled out diagonally along the chamfered portion 211. This makes it less likely for the wire 3 to bend in the flange portion 21a, and makes it easier to pull the wire 3 from the flange portion 21a to the protrusion portion 28a.

[0075] Furthermore, the bobbin 2 has a leg portion 26a that protrudes from the flange portion 21a along the axial direction of the cylindrical portion 20, and a connecting passage 27 provided between the cylindrical portion 20 and the leg portion 26a. The connecting passage 27 guides the wire 3 toward the cylindrical portion 20 in order to wind the wire 3 onto the cylindrical portion 20. When forming the first layer 35 on the outer surface of the cylindrical portion 20, pulling the wire 3 toward the protrusion 28a through the connecting passage 27 makes it less likely for the wire 3 to shift position and makes it easier to pull the wire 3 toward the protrusion 28a.

[0076] Furthermore, the coil device 1 has flanges 21a and 21b that face each other in the axial direction of the cylindrical portion 20. The protrusion 28a is formed at the connection point between the cylindrical portion 20 and the flange 21a. As shown in Figure 6, the first layer 35 is in contact with the protrusion 28a while being spaced apart from the flange 21b. The contact of the first layer 35 with the protrusion 28a helps to stabilize the shape of the first layer 35. Also, the space between the first layer 35 and the flange 21b makes it easier to form a space (gap 8) at the end of the winding of the first layer 35, allowing the wire 3 to be smoothly transferred from the first layer 35 to the second layer 36.

[0077] Furthermore, if n is the number of layers of the second layer 36 along the axial direction of the cylindrical portion 20, d is the diameter of the wire 3, and D is the distance along the axial direction of the cylindrical portion 20 from flange portion 21a to flange portion 21b, then D ≤ d × (n + 1). Therefore, a space is easily formed at the end of the winding of the first layer 35, allowing the wire 3 to be smoothly transferred from the first layer 35 to the second layer 36. In addition, space is secured for forming the second layer 36, making it easier to form the second layer 36 on the outer surface of the first layer 35.

[0078] This disclosure is not limited to the embodiments described above, and can be modified in various ways within the scope of this disclosure.

[0079] For example, although the above embodiment describes an example of applying the coil device 1 to a transformer, the coil device 1 may also be applied to other electronic components (e.g., inductors).

[0080] The bobbin 2 shown in Figure 2 may have flanges 21a and 21b, but may not have a flange 21c. Also, the bobbin 2 may have a protrusion 28a (or protrusion 28b), but may not have a protrusion 28b (or protrusion 28a).

[0081] The coil device 1 shown in Figure 1 is equipped with two wires, but it may be equipped with only one wire or three or more wires. [Explanation of symbols]

[0082] 1... Coil device 2… Bobbin 20...Cylinder part 200…Through hole 21a~21c…Tsubabe 210a, 210b, 210c... Inlet groove 211... Chamfered section 212...Wire engagement section 22, 23… Core fixing part 24... partition 25...Terminal block 250...Main unit 251...hole 252...Protrusion 26a~26d…legs 27…Communication path 28a, 28b... protrusions 280…thick part 281...Thin section 282…Slope part 3…Wire 30... Coil section 31a, 31b...Drawer part 35…1st layer 350... Beginning of the reel 351... Turn 1 352... Turn 4 36…Second layer 361... Turn 1 362... Turn 5 37…Third layer 38…4th layer 4…Wire 40... Coil section 41a, 41b...Drawer part 45…1st layer 46…Second layer 47...Third layer 48…4th layer 5a, 5b... Core 50...Base section 51...Outer leg 52...middle leg 6a, 6b… Heat dissipation components 60…Top 61…outer part 62...Inner part 7a~7d…Terminal 70...Connection part 71…Mounting part 72...Holding part 8... Gap

Claims

1. A bobbin having a cylindrical portion, a flange portion protruding from the outer circumferential surface of the cylindrical portion, and a convex portion formed at the connection between the cylindrical portion and the flange portion and extending along the circumferential direction of the cylindrical portion, A wire having a coil portion wound around the cylindrical portion and a lead portion drawn out from the coil portion, The bobbin has a core attached to it, The coil portion comprises at least a first layer and a second layer arranged on the outer circumferential surface of the first layer and having more layers than the first layer along the axial direction of the cylindrical portion. The flange portion has a pull-in groove for pulling the wire toward the cylindrical portion in order to wind the wire around the cylindrical portion. The first layer has a winding start end that is continuous with the draw-out portion, When the retraction groove is viewed from a direction perpendicular to the axial direction, at least a portion of the protrusion is located on the side of the retraction groove where the winding start end is located.

2. The coil device according to claim 1, wherein the protrusion has a thick portion having a relatively thicker thickness along the axial direction and a thin portion having a relatively thinner thickness along the axial direction.

3. The coil device according to claim 2, wherein, when the retraction groove is viewed from a direction perpendicular to the axial direction, at least a portion of the thick portion is located on one side of the retraction groove, and at least a portion of the thin portion is located on the other side of the retraction groove.

4. The coil device according to claim 2 or 3, wherein the thickened portion is separate from the thinned portion.

5. The aforementioned protrusion has an inclined portion that slopes toward one end in the direction of extension of the protrusion, The coil device according to any one of claims 1 to 3, wherein in the inclined portion, the thickness of the protrusion along the axial direction decreases as it approaches the retraction groove.

6. The coil device according to claim 5, wherein the inclined portion is formed in the thickened portion and is inclined toward one end in the extending direction of the thickened portion.

7. The coil device according to claim 5, wherein when the pull-in groove is viewed from a direction perpendicular to the axial direction, the inclined portion is located on the side of the pull-in groove where the winding start end is located.

8. The coil device according to any one of claims 1 to 3, wherein the flange portion has a chamfered portion formed along the retraction groove.

9. The bobbin has a leg portion that protrudes from the flange portion along the axial direction, and a connecting passage provided between the cylindrical portion and the leg portion. The coil device according to any one of claims 1 to 3, wherein the connecting passage guides the wire toward the cylindrical portion in order to wind the wire around the cylindrical portion.

10. The flange portion has a first flange portion and a second flange portion that are opposite to each other in the axial direction. The aforementioned protrusion is formed at the connection point between the cylindrical portion and the first flange portion. The coil device according to any one of claims 1 to 3, wherein the first layer is in contact with the convex portion and spaced apart from the second flange portion.

11. The coil device according to claim 10, wherein when the number of layers of the second layer along the axial direction is n, the diameter of the wire is d, and the distance along the axial direction from the first flange to the second flange is D, D ≤ d × (n + 1).

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