Coil assembly

Abstract

To provide a coil assembly of which a winding layer of coils becomes an odd-number layer, in which a projection part is not provided to an outer peripheral surface of each coil, and each coil is formed in a substantially cylinder shape.SOLUTION: A coil assembly 10 comprises: a conductive part 16 that is wound to a first winding trunk region 21 of a winding trunk part 20; a tip end side conductive part 17 to which a coil wire 40 is wound to a third winding trunk region 23 through an inner part of a wiring groove 29 by less than one periphery; a winding wire construction part 18 that is wound so as to form a winding layer of an odd-number layer to a second winding trunk region 22; and a conductive part 19 that passes a second winding cutting part 37 of a second flange part 25 while being connected to a winding construction part 18, and returns to a gap a first flange part 24 and the second flange part 25. Thus, the coil wire 40 is wounded from a tip end side of the winding trunk part 20 up to a base end side, and a coil 41 of which a winding layer becomes the odd number layer can be easily formed.SELECTED DRAWING: Figure 1

Description

【Technical Field】 【0001】 The present invention relates to a coil assembly, and more particularly to a coil assembly having a coil with an odd number of winding layers. 【Background Art】 【0002】 A coil assembly formed by winding a coil wire around a winding region of a coil bobbin is an essential component for solenoids and voice coil motors, except for some exceptions. Also, in most coil assemblies, in order to provide a region for accommodating the connection portion between the coil wire and the lead wire on the proximal end side of the coil bobbin, the coil is made of an even number of winding layers. That is, when forming a coil by winding a coil wire around the winding region of a coil bobbin, the coil wire is started to be wound from the proximal end side end portion of the winding portion. Then, when reaching the distal end side end portion of the winding portion, the first winding layer is formed, and further wound toward the proximal end side end portion, and when reaching the proximal end side end portion, the second winding layer is formed. The third and subsequent layers are formed in the same manner. Therefore, inevitably, the number of winding layers becomes an even number. On the other hand, when it is required that the coil wire has an odd number of layers, 【0003】 FIG. 14 is a cross-sectional view showing a coil assembly according to the prior art. In FIG. 14, 100 is a coil assembly, 101 is a coil bobbin, 102 is a winding portion, 103 is a first flange portion, 104 is a second flange portion, 105 is a first partition portion, 106 is a second partition portion, 107 is a third partition portion, 108 is a third flange portion, 109 is a composite coil, 110 is a coil wire end region, 111 is a first coil portion, 112 is a first crossover wire portion, 113 is a second coil portion, 114 is a second crossover wire portion, 115 is a third coil portion, 116 is a third crossover wire portion, 117 is a fourth coil portion, 118 is a return wire portion, and 119 is a winding layer. 【0004】 Figure 14 illustrates the invention disclosed in Japanese Patent Publication No. 2008-61397. The coil assembly 100 is configured such that a composite coil 109 consisting of a first coil portion 111, a second coil portion 113, a third coil portion 115, and a fourth coil portion 117 is provided on the coil bobbin 101. Specifically, the winding drum portion 102 of the coil bobbin 101 has a first flange portion 103 at the base end, which is where the coil wire winding begins and is connected to the lead wire, a second flange portion 104 near the base end of the first flange portion 103, and a third flange portion 108 at the tip end of the winding drum portion 102. Furthermore, the coiled drum portion 102 has a first partition portion 105, a second partition portion 106, and a third partition portion 107 formed at predetermined intervals between the second flange portion 104 and the third flange portion 108. 【0005】 Then, starting from the winding body 102, which is the gap between the first flange 103 and the second flange 104 of the coil wire, the wire is wound around the gap between the second flange 104 and the first partition 105, then through the gap of the first partition 105 and then around the gap between the first partition 105 and the second partition 106, then through the second partition 106 and then around the gap between the second partition 106 and the third partition 107. Furthermore, the coil wire is wound around the gap between the third partition 107 and the gap between the third partition 107 and the third flange 108. As described above, by winding the coil wire sequentially in odd-numbered layers around the winding drum portion 102 adjacent to the tip side, a composite coil 109 is formed consisting of a first coil portion 111, a second coil portion 113, a third coil portion 115, and a fourth coil portion 117, with an odd number of winding layers 119, via the first jumper portion 112, the second jumper portion 114, and the third jumper portion 116. Finally, the coil wire is routed linearly along the outer surfaces of the first coil portion 111, the second coil portion 113, the third coil portion 115, and the fourth coil portion 117, and toward the base end side of the coil bobbin 101. By routing the return wire portion 118 in this manner, two coil wire end regions 110 are aligned toward the base end side of the coil bobbin 101, making connection to the lead wire easier. 【0006】 With the above configuration, even if the coil has an odd number of layers wound around the winding drum 102 of the coil bobbin 101, it is possible to position both ends of the coil wire and the portions near them towards the base end. Furthermore, there is the advantage that any number of coils can be formed on a single coil bobbin. However, since the return wire portion 118 is wired along the outer surfaces of the first coil portion 111, the second coil portion 113, the third coil portion 115, and the fourth coil portion 117, the return wire portion 118 protrudes from the outer surfaces of the first coil portion 111, the second coil portion 113, the third coil portion 115, and the fourth coil portion 117. In other words, the diameter of the space required to house the coil assembly 100 is the number of winding layers of the first coil portion 111, the second coil portion 113, the third coil portion 115, and the fourth coil portion 117 plus one additional layer. Furthermore, since the return wire portion 118 protrudes from the outer circumferential surfaces of the first coil portion 111, the second coil portion 113, the third coil portion 115, and the fourth coil portion 117, when the coil assembly 100 is housed in a solenoid case or the like, the case may come into contact with the area where the return wire portion 118 is located, potentially causing defects in the insulating material provided on the outer circumferential surface of the coil assembly 100. [Prior art documents] [Patent Documents] 【0007】 [Patent Document 1] Japanese Patent Publication No. 2008-61397 [Overview of the project] [Problems that the invention aims to solve] 【0008】 The present invention aims to solve the above-mentioned problems by providing a coil assembly in which the number of winding layers of the coil is odd, in which no protrusions are formed on the outer surface of the coil, and the coil is formed in a substantially cylindrical shape. [Means for solving the problem] 【0009】 The invention described in claim 1 comprises a winding drum formed in a substantially cylindrical shape, a first flange formed in a substantially annular or fan shape and located at or near the base end of the outer circumferential surface of the winding drum, and positioned perpendicular to the central axis of the winding drum, a second flange formed in a substantially annular shape and located near the base end of the outer circumferential surface of the winding drum, closer to the tip than the first flange, and positioned perpendicular to the central axis of the winding drum, a fourth flange formed in a substantially annular or fan shape and located at or near the tip end of the outer circumferential surface of the winding drum, and positioned perpendicular to the central axis of the winding drum, and a third flange formed in a substantially annular shape and located near the tip end of the outer circumferential surface of the winding drum, closer to the base than the fourth flange, and positioned perpendicular to the central axis of the winding drum. A coil assembly comprising a coil bobbin having a third flange and a coil formed by winding a coil wire around the winding drum, wherein the coil bobbin is provided with a wiring groove that extends along the central axis of the winding drum and reaches from a first winding drum region between the first flange and the second flange on the outer circumferential surface of the winding drum, through a second winding drum region between the second flange and the third flange, to a third winding drum region between the third flange and the fourth flange, wherein the second flange has a first wiring groove notch that reaches from the periphery to the wiring groove and a second winding notch that reaches from the periphery to a predetermined position near the periphery, and the third flange has a second wiring groove notch that reaches from the periphery to the wiring groove and a first winding notch that reaches from the periphery to the outer circumferential surface of the winding drum. The coil assembly is characterized by comprising: an introduction portion in which the coil wire is wired to the first winding region of the winding drum; a leading end outlet portion that is continuous with the introduction portion and is wound less than one turn around the third winding region of the winding drum, passing through the wiring groove; a winding component portion that is continuous with the leading end outlet portion and is wound around the front second winding region of the winding drum, passing through the first winding notch of the third flange, to form an odd number of winding layers; and an outlet portion that is continuous with the winding component portion and passes through the second winding notch of the second flange, returning to the gap between the first flange and the second flange. 【0010】 The invention described in claim 2 is a coil assembly in which, in the invention described in claim 1, the coil bobbin is formed such that the depth of the wiring groove is equal to or greater than the diameter of the coil wire. 【0011】 The invention described in claim 3 is a coil assembly in which, in the invention described in claim 2, the coil bobbin is formed such that, in a direction perpendicular to the central axis, the distance between the bottom of the wiring groove and the central axis is greater than the distance between the first winding drum region and the central axis. 【0012】 The invention described in claim 4 is a coil assembly in which, in the invention described in claim 3, the coil bobbin comprises a first end and a second end facing the third flange portion via a second wiring groove notch, and the first end and the second end are formed such that a part or all of their outer circumferential surfaces form a convex curved surface. 【0013】 The invention described in claim 5 is the invention described in any one of claims 1 to 4, wherein the coil bobbin is formed in a substantially annular shape and further comprises a partition flange portion located between the second flange portion and the third flange portion on the outer circumferential surface of the winding drum portion, and arranged in a direction perpendicular to the central axis of the winding drum portion, wherein the partition flange portion has a third wiring groove notch portion extending from the periphery to the wiring groove and a folding notch portion extending from the periphery in the tangential direction of the winding drum portion, and the coil has the winding component portion continuous with the tip side lead portion and front The coil assembly is characterized by comprising: a coil portion in a first direction, which is wound in the region between the third flange portion and the partition flange portion of the winding drum, passing through the first winding notch portion of the third flange portion, so as to form an odd number of winding layers; and a coil portion in a second direction, which is continuous with the portion in the first direction and passes through the folding notch portion of the partition flange portion, so as to form an odd number of winding layers in the region between the partition flange portion and the second flange portion, in the opposite direction to the winding layers in the gap between the third flange portion and the partition flange portion of the winding drum. [Effects of the Invention] 【0014】 According to the invention described in claim 1, the coil includes an introduction section wired in the first winding drum region of the winding drum, a tip-side exit section through which the coil wire passes inside the wiring groove and is wound less than one turn around the third winding drum region, a winding component section wound in the second winding drum region to form an odd number of winding layers, and an exit section that is continuous with the winding component section, passes through the second winding notch of the second flange, and returns to the gap between the first flange and the second flange. As a result, the coil wire is wound starting from the tip side of the winding drum and ending at the base end, making it easy to form a coil with an odd number of winding layers. Furthermore, since the tip-side exit section is led out to the tip side of the coil bobbin through the inside of the wiring groove, the diameter of the coil does not increase by the amount of one winding layer, as in the conventional technique where the winding layer passes through the outer surface of the winding layer and returns to the base end side of the coil bobbin. 【0015】 According to the invention described in claim 2, the coil wire passing through the inside of the wiring groove does not protrude above the wiring groove, so the winding component can be precisely formed into a cylindrical shape. 【0016】 According to the invention described in claim 3, since the coil wire has a slight upward slope from the first winding drum region toward the bottom of the wiring groove, when the coil wire is routed into the wiring groove following the introduction section, the coil wire is lightly pressed against the bottom of the wiring groove, thereby preventing sagging that can cause the coil wire to become distorted. 【0017】 According to the invention described in claim 4, when the coil wire is routed through the second wiring groove notch of the third flange, it is possible to prevent the coil wire from being pressed against the corner between the first end and the second end and deforming. 【0018】 According to the invention described in claim 5, the addition of a partition flange makes it easier to form a coil assembly for a voice coil motor that has multiple coils. [Brief explanation of the drawing] 【0019】 [Figure 1] The coil bobbin of a coil assembly according to the first embodiment of the present invention is shown, where (a) is a front view, (b) is a left side view, and (c) is a right side view. [Figure 2] The coil bobbin of the coil assembly according to the first embodiment of the present invention is shown, (a) a horizontal cross-sectional view in the direction of the central axis, (b) a vertical cross-sectional view in the direction of the central axis, (c) a cross-sectional view along line BB, and (d) a cross-sectional view along line AA. [Figure 3] The coil bobbin of the coil assembly according to the first embodiment of the present invention is shown, where (a) is a partially enlarged view of the base end region of the wiring groove, and (b) is a partially enlarged view of the tip end region of the wiring groove. [Figure 4] This is an explanatory diagram (1) showing the coil formation procedure for a coil assembly according to the first embodiment of the present invention. [Figure 5]It is an explanatory diagram (2) showing the coil forming procedure of the coil assembly according to the first embodiment of the present invention. [Figure 6] It is an explanatory diagram (3) showing the coil forming procedure of the coil assembly according to the first embodiment of the present invention. [Figure 7] It is an explanatory diagram showing the configuration of the coil of the coil assembly according to the first embodiment of the present invention. [Figure 8] The coil bobbin for a voice coil motor of the coil assembly according to the second embodiment of the present invention is shown, (a) is a front view, (b) is a left side view, and (c) is a right side view. [Figure 9] It is a vertical cross-sectional view in the direction of the central axis of the coil bobbin for a voice coil motor of the coil assembly according to the second embodiment of the present invention. [Figure 10] The coil bobbin for a voice coil motor of the coil assembly according to the second embodiment of the present invention is shown, (a) is a cross-sectional view taken along line C-C, (b) is a cross-sectional view taken along line D-D, and (c) is a cross-sectional view taken along line E-E. [Figure 11] It is an explanatory diagram (1) showing the coil forming procedure of the coil assembly according to the second embodiment of the present invention. [Figure 12] It is an explanatory diagram (2) showing the coil forming procedure of the coil assembly according to the second embodiment of the present invention. [Figure 13] A modified example of the coil assembly according to the embodiment of the present invention is shown, (a) is a front view of the coil bobbin of the coil assembly according to the first embodiment, (b) is a cross-sectional view of a modified example of the coil bobbin for a voice coil motor of the coil assembly according to the second embodiment of the present invention, and (c) is a cross-sectional view taken along line F-F. [Figure 14] It is a cross-sectional view showing a coil assembly according to the prior art. 【Embodiments for Carrying Out the Invention】 【0020】 First, in the description of the coil assembly of the embodiment of the present invention described below, and in the claims, "base end side" refers to the side on which the coil wire begins to be wound around the winding drum of the coil bobbin or voice coil motor coil bobbin, and "tip end side" refers to the side opposite to the base end side, that is, the side on which the winding layer of the coil wire is finished to be wound. In the coil assembly of the embodiment of the present invention, both ends of the coil wire are positioned on the "base end side" of the coil bobbin. Furthermore, "central axis" refers to the central axis of the winding drum of the coil bobbin, and this "central axis" coincides with the central axis of the shaft. 【0021】 Figure 1 shows the coil bobbin of a coil assembly according to the first embodiment of the present invention, where (a) is a front view, (b) is a left side view, and (c) is a right side view. In Figure 1, 15 is the coil bobbin, 20 is the winding drum portion, 21 is the first winding drum region, 22 is the second winding drum region, 23 is the third winding drum region, 24 is the first flange portion, 25 is the second flange portion, 26 is the third flange portion, 27 is the fourth flange portion, 29 is the wiring groove, 29a is the base end portion, 29b is the tip end portion, 30a is the first serration portion, 30b is the second serration portion, 31 is the coil forming region, 32 is the fan-shaped notch portion, and 33 is the hollow portion. Figure 2 shows the coil bobbin of a coil assembly according to the first embodiment of the present invention, where (a) is a horizontal cross-sectional view in the direction of the central axis, (b) is a vertical cross-sectional view in the direction of the central axis, (c) is a cross-sectional view along line BB, and (d) is a cross-sectional view along line AA. In Figure 2, 28 is a reinforcing portion, 30c is a third serration portion, 34 is a first wiring groove notch, 35 is a second wiring groove notch, 36 is a first winding notch, and 37 is a second winding notch, and other reference numerals are the same as in Figure 1. Furthermore, Figure 3 shows the coil bobbin of a coil assembly according to the first embodiment of the present invention, where (a) is a partially enlarged view of the tip side region of the wiring groove, and (b) is a partially enlarged view of the base side region of the wiring groove. All reference numerals used in Figure 3 are the same as in Figure 1. In addition, Figure 5 is an explanatory diagram (2) showing the coil formation procedure of a coil assembly according to the first embodiment of the present invention. In Figure 5, 25a is the first end, 25b is the second end, 26a is the first end, 26b is the second end, 30d is the fourth serration, 38a, 38b, 38c, 38d, 39a, 39b, 39c and 39d are curved surface forming portions, 40 is the coil wire, 40a is the coil wire start end, and 95 is the gap. Other reference numerals are the same as in Figure 1. Figure 5 shows a rear view of the coil bobbin 15. 【0022】 First, the configuration of the coil bobbin of the coil assembly according to the first embodiment of the present invention will be described. As shown in Figures 1 and 2, the coil bobbin 15 of the coil assembly according to this embodiment is provided with a first flange 24, a second flange 25, a third flange 26, and a fourth flange 27 on the winding drum portion 20. The winding drum portion 20 is formed in a substantially cylindrical shape, and although not shown, when the coil bobbin 15 is assembled into a solenoid or the like, a movable magnetic pole and a shaft (not shown) are arranged in the hollow portion 33. Furthermore, the winding drum portion 20 is divided into three regions, the first winding drum region 21, the second winding drum region 22, and the third winding drum region 23, by the second flange portion 25 and the third flange portion 26. As shown in Figure 1, only the second winding drum region 22 becomes the coil formation region 31, while the first winding drum region 21 and the third winding drum region 23 are used for connecting the coil wire start end 40a of the coil wire 40 to the lead wire, or for switching the winding direction or wiring direction of the coil wire, as shown in Figure 5. 【0023】 Furthermore, as shown in Figure 1, a wiring groove 29 is formed on the outer circumferential surface of the winding drum 20 along the central axis. The wiring groove 29 extends from the base end to the tip end of the winding drum 20 and is formed to wire and house the portion near the coil wire starting end 40a, which is the side where the coil wire 40 begins to be wound. Moreover, as shown in Figure 3, the base end 29a of the wiring groove 29 reaches the first winding drum region 21, and the tip end 29b crosses the third winding drum region 23 in the direction of the central axis and reaches the fourth flange 27. Also, as shown in Figures 2(a) and (d), in the direction perpendicular to the central axis, the distance between the bottom of the base end 29a and the central axis is formed to be greater than the distance between the outer circumferential surface of the first winding drum region 21 and the central axis. This configuration works because, when the coil wire 40 is routed from the first winding drum region 21 toward the wiring groove 29 by the procedure described later, the coil wire 40 has a slight upward slope toward the bottom of the base end 29a. As a result, when the coil wire 40 is routed into the wiring groove 29, the coil wire 40 is lightly pressed against the bottom of the wiring groove 29, preventing sagging that would cause the coil wire 40 to become distorted. 【0024】 Furthermore, as shown in Figures 2(a) and (c), in the direction perpendicular to the central axis, the distance between the bottom of the tip end 29b and the central axis is formed to be smaller than the distance between the outer surface of the third winding drum region 23 and the central axis. This configuration is also intended to prevent deflection that causes winding irregularities in the coil wire 40, as the coil wire 40 will have a slight upward slope towards the third winding drum region 23 when the coil wire 40 is routed from the wiring groove 29 toward the third winding drum region 23 by the procedure described later. 【0025】 Furthermore, the depth to the bottom of the wiring groove 29 is formed to be equal to the diameter of the coil wire 40 in order to prevent the coil wire 40 from protruding because it cannot be fully housed in the wiring groove 29, thereby deforming the shape of the coil. Note that the winding drum 20 is formed with a certain degree of extra thickness to prevent deformation due to the stress applied when the coil wire is wound, so the depth to the bottom may be formed to be equal to the diameter of the thickest coil that can be wound on the coil bobbin 15, so that it can be applied to coil wires of various diameters. In this case, the depth to the bottom will be greater than the diameter of most coil wires used to form the coil, so relatively thin coil wires will be hidden inside the wiring groove 29. The width of the wiring groove 29 should be sufficient to allow one coil wire 40 to be wired. If this width is excessive, it will cause distortion in the shape of the coil, so it is desirable to have a width that is necessary and sufficient for wiring one coil wire 40. Considering the above conditions, it is most desirable for the depth and width of the wiring groove 29 to be equal to the diameter of the coil wire actually wound around it, but it can be said that there is almost no problem even if it is formed to be slightly larger than the diameter of the coil wire actually wound around it. 【0026】 The first flange portion 24 is formed in a substantially fan-shaped form and is provided to protrude in a direction perpendicular to the central axis at the base end of the outer circumferential surface of the winding drum portion 20. The first flange portion 24 may also be formed in a substantially annular shape and provided with a notch for passing lead wires, which will be described later. Furthermore, for reasons such as using the base end of the winding drum portion 20 to fix the coil bobbin 15, the first flange portion 24 may be provided at a position slightly towards the tip of the base end of the winding drum portion 20, that is, at a position near the base end. In addition, the first flange portion 24 has a fan-shaped notch portion 32 formed on the upper side, that is, on the side opposite to the area where the reinforcing portion 28 that reinforces the first flange portion 24 is formed. The fan-shaped notch 32 is formed to allow lead wires (not shown) to be led out to the outside, and is also positioned between the first wiring groove notch 34 and the second winding notch 37, which will be described later. 【0027】 As shown in Figure 2, the second flange portion 25 is formed in a substantially annular plate shape and is provided to protrude in a direction perpendicular to the central axis near the base end of the outer circumferential surface of the winding drum portion 20. Furthermore, the second flange portion 25 is formed at a predetermined distance from the base end of the outer circumferential surface of the winding drum portion 20 in order to secure space for wiring the coil wire start end 40a of the coil wire 40 and lead wires in the gap between it and the first flange portion 24. In addition, the second flange portion 25 has a first wiring groove notch 34 that extends from the periphery to the wiring groove 29, and a second winding notch 37 that extends from the periphery to a predetermined position near the periphery. The first wiring groove notch 34 is for routing the coil wire 40 from the base end to the tip end through the second flange portion 25, and the second flange portion 25 is shaped to be cut from the periphery to the wiring groove 29, and with the same width as the wiring groove 29. 【0028】 The second winding notch 37 is for returning the coil wire 40 to the gap between the first flange 24 and the second flange 25 after winding the coil wire 40 around the second winding drum region 22 to form an odd number of winding layers. Furthermore, since the second winding notch 37 is for leading out the coil wire 40 after the odd number of winding layers have been formed, that is, at a position away from the outer circumferential surface of the winding drum 20, it is formed in a direction perpendicular to the central axis, from the periphery to the position where the odd number of winding layers have been formed. In addition, as shown in Figure 5, it is provided with a first end 25a and a second end 25b facing each other via the second winding notch 37. The first end 25a and the second end 25b have curved surface forming portions 38a and 38b and curved surface forming portions 38c and 38d, which are curved surface forming portions 38c and 38d, with a part of the outer circumferential surface being a convex curved surface. In this way, a portion of the outer surface of the first end 25a and the second end 25b is made into a convex curved surface without corners, thereby reducing stress caused by the coil wire 40 being greatly bent when it comes into contact with that portion. Furthermore, the first flange portion 24 and the second flange portion 25 are formed with a second serration portion 30b and a fourth serration portion 30d, and a first serration portion 30 and a third serration portion 30c, as shown in Figures 1 and 5, in order to clamp and hold lead wires (not shown). 【0029】 As shown in Figures 1 and 2, the fourth flange portion 27 is formed in a substantially annular plate shape and is provided to protrude in a direction perpendicular to the central axis at the tip end of the outer circumferential surface of the winding drum portion 20. The fourth flange portion 27 may also be provided at a position slightly closer to the base end than the tip end of the winding drum portion 20, i.e., near the tip end, for reasons such as using the tip end of the winding drum portion 20 to fix the coil bobbin 15. The third flange portion 26 is formed in a substantially annular plate shape and is provided to protrude in a direction perpendicular to the central axis near the tip end of the outer circumferential surface of the winding drum portion 20. Furthermore, the third flange portion 26 is formed at a predetermined distance from the tip end of the outer circumferential surface of the winding drum portion 20 in order to secure space for wiring the aforementioned coil wire 40 in the gap between it and the fourth flange portion 27. In addition, the third flange portion 26 has a second wiring groove notch 35 that extends from the periphery to the wiring groove 29, and a first winding notch 36 that extends from the periphery to the outer surface of the winding drum portion 20. 【0030】 The second wiring groove notch 35 is for routing the coil wire 40 from the base end through the third flange 26 to the first winding drum region 21, and the second flange 25 is shaped by cutting from the periphery to the wiring groove 29, with the same width as the wiring groove 29. The first winding notch 36 is formed to switch the direction of the coil wire 40, which is routed toward the tip, toward the base end. That is, the coil wire 40 routed through the wiring groove 29 to the first winding drum region 21 is wound around the third winding drum region 23 for about half a turn, and then returns to the second winding drum region 22 through the first winding notch 36, as shown in Figure 5. Furthermore, the first winding notch 36 is formed such that, in a direction perpendicular to the central axis, the bottom of the first winding notch 36 and the outer surface of the second winding drum region 22 are equal in distance from the central axis, in order to prevent winding irregularities when winding the coil wire 40 in the second winding drum region 22. 【0031】 Furthermore, as shown in Figure 5, the third flange portion 26 includes a first end portion 26a and a second end portion 26b that face each other via the first winding notch portion 36. The first end portion 26a and the second end portion 25b have curved surface forming portions 39a and 39b and curved surface forming portions 39c and 39d, where a part of the outer surface is a convex curved surface. Therefore, similar to the second winding notch portion 37, the first winding notch portion 36 has a convex curved surface without corners on a part of the outer surface of the first end portion 26a and the second end portion 26b, so that stress caused by the coil wire 40 that comes into contact with that portion bending significantly can be suppressed. Furthermore, the width of the gap 95 between the first end 26a and the second end 25b is set to be greater than the thickness of the third flange 26 in the direction of the central axis. This is intended to suppress bending of the coil wire 40 passing through the gap 95 and to reduce stress caused by excessive bending of the coil wire 40. 【0032】 Next, the procedure for forming the coil of the coil assembly according to the first embodiment of the present invention will be described. Figure 4 is an explanatory diagram (1) showing the coil formation procedure of the coil assembly according to the first embodiment of the present invention. All reference numerals used in Figure 4 are the same as those in Figure 1. Figure 6 is an explanatory diagram (3) showing the coil formation procedure of the coil assembly according to the first embodiment of the present invention. In Figure 6, 10 is the coil assembly, 40b is the coil wire end, 41 is the coil, 42 is the insulating tape, and the other reference numerals are the same as those in Figure 1. Figure 6 shows a rear view of the coil bobbin 15. Furthermore, Figure 7 is an explanatory diagram showing the coil configuration of the coil assembly according to the first embodiment of the present invention. In Figure 7, 40b is the coil wire end, and the other reference numerals are the same as those in Figure 1. 【0033】 First, as shown in Figure 4(1), the coil wire 40 is introduced from the outside of the coil bobbin 15 through the fan-shaped notch 32 of the first flange 24 to the first winding drum region 21. Furthermore, it is wound along the outer circumferential surface of the first winding drum region 21 toward the first wiring groove notch 34 of the second flange 25. Then, the coil wire 40 is routed so that it passes through the first wiring groove notch 34, and then routed into the wiring groove 29. Next, as shown in Figure 4(2), it is led out to the third winding drum region 23 by passing through the second wiring groove notch 35 of the third flange 26. Furthermore, the coil wire 40 is wound along the outer circumferential surface of the third winding drum region 23 toward the first winding notch 36. In addition, the coil wire 40 will be wound around the third winding drum region 23 for approximately half a turn, but this portion of the coil wire 40 does not constitute the coil 41. 【0034】 Next, as shown in Figure 5(3), the wire is routed through the first winding notch 36 to the second winding drum region 22. Subsequently, as shown in Figure 6(4), the coil wire 40 is wound around the second winding drum region 22. Then, as shown in Figure 6(5), once the coil 41 is formed by winding until a predetermined odd number of winding layers are formed, it is led out to the first winding drum region 21 through the second winding notch 37 of the second flange portion 25. Furthermore, the coil wire 40 is led out to the outside of the coil bobbin 15 through the fan-shaped notch 32 of the first flange portion 24. Finally, as shown in Figure 6(6), insulating tape 42 is wrapped around the coil 41 at least once to protect it. The coil wire start end 40a and coil wire end end 40b of the coil wire 40 are connected to lead wires (not shown), respectively. After these coil formation procedures, the coil assembly 10 is completed. 【0035】 As described above, the coil wire 40 that has undergone the coil formation procedure consists of an introduction section 16 shown in Figure 7(a), a tip-side lead-out section 17 shown in Figure 7(b), a winding configuration section 18 shown in Figure 7(c), and a lead-out section 19 shown in Figure 7(d). The tip-side lead-out section 17 is a part that does not exist in the prior art and is a characteristic part of the coil assembly 10 according to the first embodiment of the present invention. In addition, in the prior art coil assembly 100 shown in Figure 14, the return wire section 118 corresponds to the tip-side lead-out section 17. However, since the return wire section 118 is provided in a state that protrudes from the outer circumferential surface of the first coil section 111, the second coil section 113, the third coil section 115, and the fourth coil section 117, it may come into contact with the case when the coil assembly 100 is housed in a solenoid case or the like, causing insulation problems. In contrast, the leading end portion 17 is housed inside the wiring groove 29 formed in the winding drum portion 20, so this problem does not occur. Note that the coil formation procedure described above is just one example, and the procedure may differ in detail. 【0036】 Next, a coil assembly according to a second embodiment of the present invention will be described. Figure 8 shows the coil bobbin for a voice coil motor of the coil assembly according to the second embodiment of the present invention, where (a) is a front view, (b) is a left side view, and (c) is a right side view. In Figure 8, 14 is the coil bobbin for the voice coil motor, 50 is the winding drum, 51 is the first winding drum region, 52 is the second winding drum region, 53 is the third winding drum region, 54 is the fourth winding drum region, 55 is the fifth winding drum region, 56 is the first flange, 57 is the second flange, 57a is the notch for the first wiring groove, 58 is the first partition flange, 58a is the notch for the third wiring groove, 59 is the second partition flange, 59a is the notch for the fourth wiring groove, 60 is the third flange, 61 is the fourth flange, 62 is the wiring groove, 62a is the base end, 62b is the tip end, 63 is the hollow section, and 64 is the shaft. Figure 9 is a vertical cross-sectional view of the coil bobbin for a voice coil motor of a coil assembly according to a second embodiment of the present invention, in the direction of the central axis. In Figure 9, 65 is the first coil forming region, 66 is the second coil forming region, and 67 is the third coil forming region, and other reference numerals are the same as in Figure 8. Furthermore, Figure 10 shows the coil bobbin for a voice coil motor of a coil assembly according to a second embodiment of the present invention, where (a) is a cross-sectional view along line CC, (b) is a cross-sectional view along line DD, and (c) is a cross-sectional view along line EE. In Figure 10, 55a is a flat surface, 58b is a notch for folding, 59b is a notch for folding, 60a is a notch for the second wiring groove, and 60b is a notch for wrapping around, and other reference numerals are the same as in Figure 8. In addition, Figure 11 is an explanatory diagram (1) showing the coil forming procedure of a coil assembly according to a second embodiment of the present invention. In Figure 11, 43 is the coil wire, 43a is the starting end of the coil wire, and other reference numerals are the same as in Figure 8. 【0037】 First, the configuration of the coil bobbin for the voice coil motor of the coil assembly according to the second embodiment of the present invention will be described. As shown in Figures 8 and 9, the coil bobbin 14 for the voice coil motor of the coil assembly according to this embodiment is formed in a substantially bottomed cylindrical shape with a hollow portion 63 and a bottom on the base end side of the winding drum portion 50, and a shaft 64 that supports the movable member of the voice coil motor so as to be able to move in a straight line is fixed to this bottom on the base end side. In addition, the coil bobbin 14 for the voice coil motor may be configured to have a bottom on the tip side of the winding drum portion 50, and the shaft 64 may be fixed to this bottom on the tip side. Furthermore, the arrangement of the first coil forming region 65, the second coil forming region 66, and the third coil forming region 67 in the central axis direction and their respective lengths are not limited to those shown in Figure 8, etc., and can be appropriately changed according to the specifications required for the coil assembly. 【0038】 Furthermore, the winding drum portion 50 is provided with a first flange portion 56, a second flange portion 57, a first partition flange portion 58, a second partition flange portion 59, a third flange portion 60, and a fourth flange portion 61 in order to form three coils that serve as the power source for the voice coil motor. In other words, by providing a first partition flange 58 and a second partition flange 59 between the second flange 57 and the third flange 60, the winding drum 50 is divided into five regions: a first winding drum region 51, a second winding drum region 52, a third winding drum region 53, a fourth winding drum region 54, and a fifth winding drum region 55. The second winding drum region 52, the third winding drum region 53, and the fourth winding drum region 54 are designated as the first coil forming region 65, the second coil forming region 66, and the third coil forming region 67, respectively. 【0039】 As shown in Figure 11, the first winding drum region 51 and the fifth winding drum region 55 are regions used for connecting the coil wire starting end 43a of the coil wire 43 to a lead wire (not shown), or for switching the winding direction or wiring direction of the coil wire. As shown in Figures 8 and 9, a wiring groove 62 is formed on the outer circumferential surface of the winding drum 50 along the central axis. The wiring groove 62 extends from the base end to the tip end of the winding drum 50, and as shown in Figure 11, it is formed to wire and house the portion near the coil wire starting end 43a, which is the side where the winding of the coil wire 43 begins. Furthermore, the base end 62a of the wiring groove 62 reaches the first winding drum region 51, and the tip end 62b reaches the fourth flange 61 so as to divide the fifth winding drum region 55. In other words, as shown in Figure 10(a), the winding drum portion 50 is formed with a flat surface 55a in part of the fifth winding drum region 55, and furthermore, the distance from the central axis of the wiring groove 62 and the flat surface 55a are equal, so that the flat surface 55a forms part of the wiring groove 62. 【0040】 As shown in Figures 8 and 9, the first flange portion 56 is formed in a short, substantially cylindrical shape and is provided to protrude in a direction perpendicular to the central axis at the base end of the outer circumferential surface of the winding drum portion 50. The second flange portion 57 is formed in a short, substantially cylindrical shape and is provided to protrude in a direction perpendicular to the central axis near the base end of the outer circumferential surface of the winding drum portion 50. Furthermore, as described above, the second flange portion 57 is formed at a predetermined distance from the first flange portion 56 in order to secure space for wiring the coil wire start end 43a of the coil wire 43 and lead wires. In addition, the second flange portion 57 has a first wiring groove notch 57a that extends from the periphery to the wiring groove 62. 【0041】 The first partition flange 58 is positioned to make the second winding region 52 of the winding drum 50 between it and the second flange 57, and the third winding region 53 of the winding drum 50 between it and the second partition flange 59, into coil formation regions. Furthermore, as shown in Figure 10(c), the first partition flange 58 has a third wiring groove notch 58a that extends from the periphery to the wiring groove 62, and a folding notch 58b that extends from the periphery to the second winding region 52 and the third winding drum region 53, and cuts the first partition flange 58 in the tangential direction. The folding notch 58b is formed to wind the coil wire 43 in opposite directions to the second winding region 52 and the third winding drum region 53, as will be described later. In other words, the coil wire 43 is wound in such a way that it is secured to the folding notch 58b, that is, the coil wire 43 is folded back at the folding notch 58b, thereby reversing the winding direction. 【0042】 The second partition flange 59 is positioned to form a coil in the third winding region 53 of the winding drum 50 between it and the first partition flange 58, and in the fourth winding region 54 of the winding drum 50 between it and the third flange 60. As shown in Figure 10(b), the second partition flange 59 has a fourth wiring groove notch 59a that extends from the periphery to the wiring groove 62, and a folding notch 59b that extends from the periphery to the third winding region 53 and the fourth winding region 54, and cuts the second partition flange 59 in the tangential direction. The folding notch 59b is formed to wind the coil wire 43 in opposite directions to the third winding region 53 and the fourth winding region 54, as will be described later. In other words, the coil wire 43 is secured to the folding notch 59b, that is, the coil wire 43 is folded back at the folding notch 59b and wound in such a way that the winding direction is reversed. 【0043】 The third flange portion 60 is positioned in this location with the aim of making the fourth winding drum region 54 of the winding drum portion 50, which is between it and the second partition flange portion 59, a coil formation region. Furthermore, as shown in Figure 11, the third flange portion 60 also aims to switch the winding direction or wiring direction of the coil wire 43 in order to wind the coil wire 43 into the fourth winding drum region 54 after it has been wired inside the wiring groove 62 between it and the fourth flange portion 61. In addition, as shown in Figure 10(a), the third flange portion 60 has a second wiring groove notch 60a that extends from the periphery to the wiring groove 62, and a wrap-around notch 60b that extends from the periphery to the third winding drum region 53 and the fourth winding drum region 54, and cuts into the second partition flange portion 59 in its tangential direction. The wrap-around notch 60b is formed to move the coil wire 43, which has been introduced from the wiring groove 62 into the fifth winding drum region 55, to the fourth winding drum region 54, as will be described later. In other words, the wrap-around notch 60b is used to guide the coil wire 43 into the fourth winding drum region 54. 【0044】 The fourth flange portion 61 is formed in a substantially annular plate shape and is provided to protrude in a direction perpendicular to the central axis at the leading edge of the outer circumferential surface of the winding drum portion 50. The second flange portion 57, the first partition flange portion 58, the second partition flange portion 59, and the third flange portion 60 have a first wiring groove notch 57a, a third wiring groove notch 58a, a fourth wiring groove notch 59a, and a second wiring groove notch 60a formed therein to allow the wiring groove 62 to pass through. The first wiring groove notch 57a, the third wiring groove notch 58a, the fourth wiring groove notch 59a, and the second wiring groove notch 60a are shaped to be cut from their respective peripheries to the wiring groove 62 and to have the same width as the wiring groove 62. As described above, the coil bobbin 14 for the voice coil motor is equipped with a first partition flange 58 and a second partition flange 59, thereby forming a first coil forming region 65, a second coil forming region 66, and a third coil forming region 67, as shown in Figure 9. Furthermore, it is possible to wind the coil wire 43 in opposite directions between adjacent regions. 【0045】 The procedure for forming the coil of the coil assembly according to the second embodiment of the present invention described above will now be explained. Figure 12 is an explanatory diagram (2) showing the procedure for forming the coil of the coil assembly according to the second embodiment of the present invention. In Figure 12, 11 is the coil assembly, 43b is the coil wire end, 43c is the wrap-around part, 43d is the first folded part, 43e is the second folded part, 44 is the first coil part, 45 is the second coil part, 46 is the third coil part, 47, 48 and 49 are insulating tapes, and other reference numerals are the same as in Figures 8 and 11. 【0046】 First, as shown in Figure 11(1), the coil wire 43 is introduced from the base end side of the voice coil motor coil bobbin 14, that is, from the peripheral edge side of the first flange 56 to the first winding drum region 51. Furthermore, it is wound along the outer surface of the first winding drum region 51 toward the first wiring groove notch 57a of the second flange 57. Then, the coil wire 43 is routed so that it passes through the first wiring groove notch 57a, and then routed into the wiring groove 62. Next, as shown in Figure 11(2), it is led out to the fifth winding drum region 55 by passing through the second wiring groove notch 60a of the third flange 60. Furthermore, the coil wire 43 is wound along the outer surface of the fifth winding drum region 55 toward the wrap-around notch 60b, and then moved toward the fourth winding drum region 54 at the wrap-around notch 60b. Note that the coil wire 43 in the fifth winding drum region 55 is not part of the coil. Next, as shown in Figure 11(3), the coil wire 43 following the wrap-around portion 43c is wound around the fourth winding drum region 54. 【0047】 As shown in Figure 12(4), once the first coil section 44, which has an odd number of layers, is formed in the fourth winding drum region 54, it is moved to the third winding drum region 53 via the folding notch 59b. Then, the coil wire 43 following the first folding notch 43d is wound in the reverse direction in the third winding drum region 53, and once the second coil section 45, which has an odd number of layers, is formed, it is further moved to the second winding drum region 52 via the folding notch 58b. Then, the coil wire 43 following the second folding notch 43e is wound in the reverse direction again in the second winding drum region 52, forming the third coil section 46, which has an odd number of layers, as shown in Figure 12(5). The coil wire 43 is then led out to the peripheral edge side of the first flange 56 through the inside of the wiring groove 62. Finally, as shown in Figure 12(6), the coil assembly 11 is completed by wrapping insulating tapes 47, 48, and 49 around the first coil section 44, the second coil section 45, and the third coil section 46 at least once. 【0048】 According to the above formation procedure, a first coil portion 44 wound in the first direction, a second coil portion 45 wound in the second direction, and a third coil portion 46 wound in the first direction are continuously formed via the first folded portion 43d and the second folded portion 43e. Furthermore, according to the inventor's findings, a strong tensile stress may be temporarily applied to the first folded portion 43d and the second folded portion 43e during the formation of the second coil portion 45 and the third coil portion 46. Therefore, it is desirable to intentionally introduce slack, or looseness, into the coil wire 43 after the winding of the first coil portion 44 and the second coil portion 45 is complete. Specifically, it is desirable to introduce slack after the formation of the second coil portion 45 but before wiring to the first folded portion 43d, and to introduce slack after the formation of the third coil portion 46 but before wiring to the second folded portion 43e. 【0049】 Next, modified examples of the coil assemblies according to the first and second embodiments of the present invention will be described. Figure 13 shows modified examples of the coil assemblies according to embodiments of the present invention, where (a) is a front view of the coil bobbin of the coil assembly according to the first embodiment, (b) is a cross-sectional view of a modified example of the coil bobbin for the voice coil motor of the coil assembly according to the second embodiment of the present invention, and (c) is a cross-sectional view along the FF line. In Figure 13, 70 is the coil bobbin, 71 is the first winding drum region, 72 is the second winding drum region, 73 is the third winding drum region, 74 is the first flange, 75 is the second flange, 75a is the first end, 75b is the second end, 76 is the third flange, 77 is the fourth flange, 78a is the curved surface forming portion, 78b is the curved surface forming portion, 80 is the coil bobbin for the voice coil motor, 83 is the third winding drum region, 85a is the flat surface, 88 is the third flange, 88a is the notch for the wiring groove, 88b is the notch for folding, 89a and 89b are the curved surface forming portions, 93 is the hollow portion, and 94 is the shaft. 【0050】 Figure 13(a) shows a modified example of the coil assembly according to the first embodiment of the present invention. The coil bobbin 70 has curved surface forming portions 78a and 78b at the first end 75a and second end 75b of the second flange portion 75, where the area on the outer surface that contacts the coil wire 40 is gently curved. Note that the first winding drum region 71, the second winding drum region 72, the third winding drum region 73, the first flange portion 74, the third flange portion 76, and the fourth flange portion 77 of the coil bobbin 70, as well as other parts, have the same shape as the coil bobbin 15, so their description is omitted. As described above, the coil bobbin 70 further reduces stress on the coil wire 40 by forming the curved surface forming portions 78a and 78b. Furthermore, in the coil bobbin 80 for the voice coil motor, the two regions that are formed as corners in the coil bobbin 14 are formed as curved surface forming portions 89a and 89b in the folded-back notch portion 88b of the third flange portion 8. Note that the third winding drum region 83, the flat surface 85a, the wiring groove notch portion 88a, the hollow portion 93 and the shaft 94, as well as other parts of the coil bobbin 80 for the voice coil motor have the same shape as the coil bobbin 14 for the voice coil motor, so their description is omitted. As described above, the coil bobbin 80 for the voice coil motor further reduces stress on the coil wire 40 by forming the curved surface forming portions 89a and 89b. 【0051】 As described above, the coil assembly 10 includes an introduction section 16 wired to the first winding drum region 21 of the winding drum section 20, a tip-side exit section 17 through which the coil wire 40 passes inside the wiring groove 29 and is wound less than one turn around the third winding drum region 23, a winding component section 18 wound around the second winding drum region 22 to form an odd number of winding layers, and an exit section 19 that is continuous with the winding component section 18, passes through the second winding notch 37 of the second flange section 25 and returns to the gap between the first flange section 24 and the second flange section 25. Therefore, the coil wire 40 is wound starting from the tip side of the winding drum section 20 and ending at the base end, making it easy to form a coil 41 with an odd number of winding layers. Furthermore, since the tip-side lead-out portion 17 is led out to the tip side of the coil bobbin 15 through the inside of the wiring groove 29, the diameter of the coil does not increase by the amount of one winding layer, as in the conventional technique where the winding returns to the base end side of the coil bobbin through the outer surface of the winding layer. Moreover, even in the coil assembly 11 which includes a first coil portion 44 and a third coil portion 46 wound in the first direction, and a second coil portion 45 wound in the second direction, the diameter of the coil does not increase by the amount of one winding layer, as in the conventional technique where the winding returns to the base end side of the coil bobbin through the outer surface of the winding layer. 【0052】 Furthermore, in the coil assembly 10, since the coil wire 40 is completely housed inside the wiring groove 29, the coil wire 40 passing through the wiring groove 29 does not protrude above the wiring groove 29, and the winding component 18 can be precisely formed into a cylindrical shape. In the coil assembly 11, the coil wire 43 is completely housed inside the wiring groove 62, and a similar effect can be obtained. Moreover, in the coil assembly 10, since the coil wire 40 has a slight upward slope from the first winding drum region 21 towards the bottom of the wiring groove 29, when the coil wire 40 is wired inside the wiring groove 29 following the introduction section 16, the coil wire 40 is lightly pressed against the bottom of the wiring groove 29, preventing deflection that would cause the coil wire 40 to become distorted. In addition, in the coil bobbin 70, when the coil wire 40 is passed through the gap between the first end 75a and the second end 75b, which are the second wiring groove notches of the second flange portion 75, the coil bobbin 70 forms gently curved surfaces, the curved surface forming portions 78a and 78b, so that the coil wire 40 is not pressed against the corner of the first end 75a and the second end 75b, preventing stress and deformation. Furthermore, by further providing partition flange portions, the coil assembly 11 can be easily formed into a coil assembly for a voice coil motor, which has three coils: the first coil portion 44, the second coil portion 45, and the third coil portion 46. 【0053】 The present invention is not limited to the configuration of the embodiments described above, and can be applied to various coil assemblies as long as it does not deviate from the scope described in each claim. For example, as mentioned above, the rotor may be composed of a first rotor member and a second rotor member, both made of permanent magnets and formed in a substantially columnar shape with a fan-shaped cross-section perpendicular to the central axis, and the fan-shaped outer surfaces of the first rotor member and the second rotor member may be arranged facing away from each other to form a rotor. [Explanation of Symbols] 【0054】 10 Coil Assembly 11 Coil Assembly 14 Voice coil motor coil bobbin 15 Coil Bobbins 16 Introduction 17 Tip side lead-out part 18 Winding component 19 Derivation part 20 Reel section 21 First winding drum region 22 Second winding drum region 23 Third winding drum region 24 First guard 25. Second guard section 25a First end 25b Second end 26 Third guard 26a First end 26b Second end 27. Fourth guard section 28 Reinforcement section 29 Wiring groove 29a Proximal end 29b Tip end 30a First serration section 30b Second serration section 30c Third serration section 30d Fourth serration 31 Coil formation region 32 Fan-shaped cutout 33 Hollow part 34. First cutting section for wiring groove 35. Second cutting section for wiring groove 36 First winding cut 37 Second winding notch 38a Curved surface forming part 38b Curved surface forming part 38c Curved surface forming part 38d curved surface forming part 39a Curved surface forming part 39b Curved surface forming part 39c Curved surface forming part 39d Curved surface forming part 40b Coil wire termination 41 coils 42 Insulating tape 43 Coil Wire 43a Coil wire starting end 43b Coil wire termination 43c Wrap-around section 43d First fold 43e Second fold 44 First coil section 45 Second coil section 46 Third coil section 47. Insulating tape 48 Insulating tape 49. Insulating tape 50 Reel body 51 First winding drum region 52 Second winding drum area 53 Third winding drum area 54. Fourth winding drum region 55. Fifth winding drum area 55a flat surface 56 First guard 57 Second guard section 57a First wiring groove cut 58 First partition flange 58a Third wiring groove cut 58b Folding cut section 59 Second partition flange 59a Fourth wiring groove cut 59b Folding cut section 60 Third guard section 60a Second cutting section for wiring groove 60b Wrap-around cut section 61. Fourth guard section 62 Wiring groove 62a Proximal end 62b Tip end 63 Hollow part 64 shaft 65 First coil formation region 66 Second coil formation region 67 Third coil formation region 70 Coil Bobbins 71 First winding drum region 72 Second winding drum area 73 Third winding drum area 74 First guard 75 Second guard section 75a First end 75b Second end 76 Third guard 77. Fourth guard section 78a Curved surface forming part 78b Curved surface forming part 80 Voice Coil Motor Coil Bobbin 83 Third winding drum region 85a flat surface 88 Third guard section 88a Cutout for wiring groove 88b Folding cut section 89a Curved surface forming part 89b Curved surface forming part 93 Hollow part 94 shaft 95 Gap 100 Coil Assembly 101 Coil Bobbin 102 Winding section 103 First guard 104 Second guard section 105 First partition 106 Second partition section 107 Third partition 108 Third guard section 109 Composite Coil 110 Coil wire end region 111 First coil section 112 First crossover section 113 Second coil section 114 Second crossover section 115 Third coil section 116 Third crossover section 117 Fourth coil section 118 Return Line Section 119 layers

Claims

[Claim 1] A coil bobbin comprising: a winding drum formed in a substantially cylindrical shape; a first flange formed in a substantially annular or fan shape and located at or near the base end of the outer circumferential surface of the winding drum, and positioned perpendicular to the central axis of the winding drum; a second flange formed in a substantially annular shape and located near the base end of the outer circumferential surface of the winding drum, closer to the tip than the first flange, and positioned perpendicular to the central axis of the winding drum; a fourth flange formed in a substantially annular or fan shape and located at or near the tip end of the outer circumferential surface of the winding drum, and positioned perpendicular to the central axis of the winding drum; and a third flange formed in a substantially annular shape and located near the tip end of the outer circumferential surface of the winding drum, closer to the base than the fourth flange, and positioned perpendicular to the central axis of the winding drum. A coil assembly having a coil formed by winding a coil wire around the winding drum, The coil bobbin is provided with a wiring groove that extends along the central axis of the winding drum and reaches from a first winding drum region between the first flange and the second flange on the outer circumferential surface of the winding drum, through a second winding drum region between the second flange and the third flange, to a third winding drum region between the third flange and the fourth flange, wherein the second flange has a first wiring groove notch that extends from the periphery to the wiring groove and a second winding notch that extends from the periphery to a predetermined position near the periphery, and the third flange has a second wiring groove notch that extends from the periphery to the wiring groove and a first winding notch that extends from the periphery to the outer circumferential surface of the winding drum. The coil comprises an introduction portion in which the coil wire is wired to the first winding region of the winding drum portion, a tip-side exit portion that is continuous with the introduction portion and is wound around the third winding region of the winding drum portion less than one turn, passing through the wiring groove, a winding component portion that is continuous with the tip-side exit portion and is wound around the front second winding region of the winding drum portion in an odd number of winding layers, passing through the first winding notch of the third flange portion, and an exit portion that is continuous with the winding component portion and passes through the second winding notch of the second flange portion and returns to the gap between the first flange portion and the second flange portion. The coil assembly is characterized in that the coil bobbin is formed such that, in a direction perpendicular to the central axis, the distance between the bottom of the wiring groove and the central axis is greater than the distance between the first winding drum region and the central axis. [Claim 2] The coil bobbin comprises a first end and a second end facing the third flange portion via the second wiring groove notch, and the first end and the second end are formed such that a part or all of their outer circumferential surfaces form a convex curved surface, as described in claim 1.