JP7845658B2 - Coil bobbin - Google Patents

Description

This invention relates to a coil bobbin around which coil windings are wound.

In recent years, contactless power transmission has come into use in a wide range of fields. For example, contactless power transmission is being used in the joints of robot arms to reduce wiring (see, for example, Patent Document 1).

Japanese Patent Publication No. 2019-176692

In contactless power transmission, transmission efficiency is known to vary not only by the magnitude of the power being transmitted, but also by parameters of the transmission coil, such as the coil's inner diameter, length, winding wire diameter, and number of turns. Therefore, to improve transmission efficiency, it is necessary to select the optimal coil parameters according to the power being transmitted, and the coil's inner diameter is one of the most important parameters. However, since coils are usually constructed by winding wire around a coil bobbin with a predetermined diameter, changing the coil's inner diameter requires preparing multiple coil bobbins of different diameters, which incurs additional costs.

This invention was made to solve the above problems and aims to provide a coil bobbin in which the size of the winding section around which the winding wire is wound can be changed.

To achieve the above objective, a coil bobbin according to one aspect of the present invention is a coil bobbin on which a winding is wound, comprising: first and second flanges provided at both ends in the axial direction of the coil formed by the winding of the winding; and a winding portion provided between the first and second flanges on which the winding is wound, wherein the first and second flanges each have a plurality of small pieces that are provided to be movable in the radial direction, and the winding portion has a plurality of support members extending in the axial direction of the coil, with both ends fixed to the plurality of small pieces of the first flange and the plurality of small pieces of the second flange, respectively.
With this configuration, the size of the winding portion can be changed by moving the multiple small pieces of the first and second flange portions radially. Therefore, multiple coils with different inner diameters can be constructed using a single coil bobbin.

Furthermore, in a coil bobbin according to one aspect of the present invention, the support member may be a rod-shaped member.

Furthermore, in a coil bobbin according to one aspect of the present invention, the outer circumference of the cross-section perpendicular to the longitudinal direction of the support member may have an arc shape that is convex toward the outer circumference.
This configuration allows the coil formed by winding the wire around the winding section to be closer to a cylindrical shape.

Furthermore, in a coil bobbin according to one aspect of the present invention, the winding portion further comprises an expandable cylindrical portion provided around a plurality of support members, and the winding wire may be wound around the outer circumference of the cylindrical portion.
This configuration prevents the winding from entering the inner circumference of multiple support members, thus preventing, for example, the winding from being cut.

Furthermore, in a coil bobbin according to one aspect of the present invention, the small piece members are provided with elongated holes extending in the radial direction, and the first and second flange portions may each further have fixing portions that releasely secure the multiple small piece members by bolts with through holes formed on their central axes, which are inserted into each elongated hole of the multiple small piece members, and nuts that are screwed onto the bolts.
With this configuration, the fixing part can be used to fix the positions of multiple support members so that the winding part becomes the desired size.

Furthermore, a coil bobbin according to one aspect of the present invention may further include an expansion/contraction mechanism that can expand or contract the diameter of the winding portion by moving a plurality of small piece members of the first flange portion in the radial direction.
With this configuration, the size of the winding section can be changed by the expansion and contraction mechanism.

Furthermore, in a coil bobbin according to one aspect of the present invention, the expansion and contraction mechanism includes a plate-shaped member arranged parallel to a first flange, and a plurality of rod-shaped members, each having a first end rotatably connected to the plate-shaped member and a second end rotatably connected to the outer circumference of a small piece member of the first flange. The connection points between the first ends of the plurality of rod-shaped members and the plate-shaped member are located on the circumference of a first circle centered on the central axis of the coil, and the connection points between the second ends of the plurality of rod-shaped members and the first flange are located on the circumference of a second circle centered on the central axis of the coil and having a larger diameter than the first circle. By changing the distance between the plate-shaped member and the first flange, the plurality of small pieces members of the first flange can be moved radially.
With this configuration, the size of the winding portion can be changed by varying the distance between the plate-like member and the first flange portion.

Furthermore, in a coil bobbin according to one aspect of the present invention, a cylindrical member with a cylindrical shape covering the expansion and contraction mechanism may be further provided, and the central axis of the cylindrical member may coincide with the central axis of the coil.
This configuration protects the expansion and contraction mechanism, and also allows the coil bobbin to be detachably attached to the mounting object by, for example, fitting a cylindrical member into a cylindrical recess provided on the mounting object.

According to one aspect of the present invention, since the size of the winding section around which the winding wire is wound can be changed, it is possible to construct multiple coils with different inner diameters using a single coil bobbin.

Front view showing a coil bobbin according to an embodiment of the present invention. Plan view showing a coil bobbin according to the same embodiment. Plan view showing a coil bobbin according to the same embodiment. Plan view showing a small piece member in the same embodiment. Front view showing the coil bobbin with the windings wound on in the same embodiment. Front view showing the coil bobbin with the cylindrical part attached in the same embodiment. Front view showing a coil bobbin having an expansion/contraction mechanism in the same embodiment. Plan view showing a coil bobbin having an expansion/contraction mechanism in the same embodiment. Front view showing a coil bobbin with a cylindrical member attached in the same embodiment. Cross-sectional view showing restricting members attached to multiple support members in the same embodiment. Plan view showing another example of a coil bobbin according to the same embodiment.

The coil bobbin according to the present invention will be described below using embodiments. In the following embodiments, components denoted by the same reference numerals are identical or equivalent, and their repeated explanation may be omitted. The coil bobbin according to this embodiment allows for changing the size of the winding section around which the winding wire is wound.

Figure 1 is a front view of the coil bobbin 1 according to this embodiment, and Figures 2 and 3 are plan views of the coil bobbin 1. The coil bobbin 1 in Figure 3 is for constructing a coil with a smaller inner diameter than the coil bobbin 1 in Figure 2. Figure 4 is a plan view of a single small component 21.

The coil bobbin 1 is a device around which a winding wire is wound to form a coil. It comprises a first flange portion 2 and a second flange portion 3 provided at both ends of the coil in the axial direction, and a winding portion 4 provided between the first and second flange portions 2 and 3, around which the winding wire is wound.

The first flange portion 2 has a plurality of small piece members 21a to 21f and a fixing portion 23 for releasably fixing the plurality of small piece members 21a to 21f. The fixing portion 23 has a bolt 24 and a nut 25. The second flange portion 3 has a plurality of small piece members 31a to 31f and a fixing portion 33 for releasably fixing the plurality of small piece members 31a to 31f. The fixing portion 33 has a bolt 34 and a nut 35. Note that when not specifically distinguishing between the small piece members 21a to 21f, they may be referred to as small piece member 21. The same applies to the other components.

The winding section 4 has a plurality of support members 41a to 41f that support the wound winding. Each support member 41 extends in the axial direction of the coil. In this embodiment, the case where the support member 41 is a rod-shaped member will be mainly described, but as will be described later, the support member 41 may have other shapes. The plurality of support members 41 may all be the same shape, for example. The shape of the cross-section perpendicular to the longitudinal direction of the rod-shaped support member 41 may be circular, as shown in Figure 2, or it may be polygonal. Both ends of the plurality of support members 41a to 41f are fixed to a plurality of small piece members 21a to 21f and a plurality of small piece members 31a to 31f, respectively. That is, the first ends of the support members 41a to 41f are fixed to the small piece members 21a to 21f, and the second ends of the small piece members 21a to 21f opposite to the first ends are fixed to the small piece members 31a to 31f, respectively. The method of fastening is not particularly limited, but it may include methods such as adhesive or screw fastening.

In the coil bobbin 1 according to this embodiment, the winding section 4 has a shape in which support members 41 are positioned at each side connecting the two base surfaces of a polygonal prism. Therefore, the coil formed by the winding wire wound around the coil bobbin 1 has a polygonal cylindrical shape. The longitudinal direction of this coil is sometimes called the axial direction of the coil, or simply the axial direction. It is preferable that the winding section 4 has a shape in which support members 41 are positioned at each side connecting the two base surfaces of a regular polygonal prism. That is, it is preferable that the inner surface of the coil in a cross-section perpendicular to the axial direction of the coil formed using the coil bobbin 1 is a regular polygon. For convenience of explanation, the straight line extending in the axial direction of the coil, passing through the center of the circle passing through each vertex of the regular polygon, will be called the central axis of the coil. The diameter of that circle is sometimes called the inner diameter of the coil.

The number of small pieces 21 and 31 in the first and second flange portions 2 and 3, and the number of support members 41 in the winding portion 4 are not particularly limited. In this embodiment, the case in which there are six small pieces 21 and 31 and six support members 41 will be described, but the number of small pieces 21 and 31 and support members 41 may be less than six or more than six. It is preferable that the number of small pieces 21 and 31 and support members 41 be three or more. The more support members 41 there are, the closer the shape of the coil becomes to a cylindrical shape, so from the viewpoint of forming a coil that is close to a cylindrical shape, it is preferable to have a larger number of support members 41. On the other hand, as the number of support members 41 increases, the number of small pieces 21 and 31 also increases, and the work for manufacturing the coil bobbin 1 becomes more complex, so from the viewpoint of productivity, it is preferable to have a smaller number of support members 41. Furthermore, while the number of small pieces 21, 31 and support members 41 are usually the same, this is not required. Even if the number of small pieces 21, 31 and support members 41 differs, it is preferable that the number of small pieces 21, 31 be greater than the number of support members 41. Also, the material of the small pieces 21, 31 and support members 41 is not particularly limited, but insulating materials are preferred, such as resin or ceramic.

The first flange portion 2 is formed in a disc shape by a plurality of small piece members 21a to 21f. The radial direction in this disc shape is sometimes simply called the radial direction. That is, the direction perpendicular to the central axis in a plane perpendicular to the central axis of the coil is sometimes called the radial direction. Each small piece member 21 is a plate-shaped member along the plane direction of the first flange portion 2, and may be a fan shape, as shown in Figure 4, or it may be a rectangular or trapezoidal shape or other shape. The plurality of small piece members 21 may all be the same shape, for example. In Figure 4, the connection points of the support member 41 are shown by dashed circles. In this embodiment, the case in which the small piece member 21 is fan-shaped will be mainly described. Each small piece member 21 is provided with an elongated hole 22 extending in the radial direction, as shown in Figure 4, for example. Furthermore, the statement that the elongated holes 22 extend radially means that when the disc-shaped first flange portion 2 is formed by a plurality of small piece members 21, the elongated holes 22 of each small piece member 21 extend radially. If the small piece member 21 is sector-shaped, the elongated holes 22 may be provided near the intersection of two line segments in the sector shape, as shown in Figure 4, for example, or they may extend in the direction of the line bisector of the central angle of the sector shape. The plurality of small piece members 21a to 21f are releasably fixed by bolts 24 inserted into each elongated hole 22 of the plurality of small piece members 21a to 21f and nuts 25 screwed onto the bolts 24. Fixing the plurality of small piece members 21a to 21f means that by tightening the nuts 25 onto the bolts 24, the overlapping small piece members 21a to 21f are pressed together and become immobile from one another. Releasing the fixation means loosening the nut 25, which allows the multiple small component members 21 to move relative to each other. The bolt 24 has a through hole 24a on its central axis. Furthermore, it is preferable that the central axis of the bolt 24 coincides with the central axis of the coil formed using the coil bobbin 1.

The second flange portion 3 has the same configuration as the first flange portion 2, therefore, a description of the second flange portion 3 is omitted. Note that the multiple small piece members 31a to 31f, the elongated hole 32, the fixing portion 33, the bolt 34, the through hole 34a, and the nut 35 in the second flange portion 3 correspond to the multiple small piece members 21a to 21f, the elongated hole 22, the fixing portion 23, the bolt 24, the through hole 24a, and the nut 25 in the first flange portion 2, respectively. When viewed from the axial direction, it is preferable that the two small piece members 21 and 31 fixed to both ends of a certain support member 41 overlap.

By loosening the nuts 25 and 35 and releasing the fixation, the small pieces 21 and 31 of the first and second flange portions 2 and 3 become movable in the radial direction. By moving the small pieces 21 and 31 in the radial direction in this state, the size of the winding portion 4 can be changed. Furthermore, if the winding portion 4 has a shape in which support members 41 are placed at the positions of each side connecting the two base surfaces of a regular polygonal prism shape before the movement of the small pieces 21 and 31, it is preferable that the winding portion 4 maintains a similar shape after the movement of the small pieces 21 and 31. Therefore, it is preferable that the small pieces 21 and 31 are moved equally in the radial direction. Note that when the nuts 25 and 35 are loosened, the small pieces 21 and 31 also become movable in the circumferential direction around the bolts 24 and 34, so it is preferable to move the small pieces 21 and 31 only in the radial direction. After the small pieces 21 and 31 have been moved, they can be fixed in place by tightening the bolts 24 and 34 and the nuts 25 and 35, respectively. When the coil wound around the winding section 4 is used for contactless power transmission or the like, it is preferable that the small pieces 21 and 31 are fixed in this manner.

Figure 2 shows the coil bobbin 1 with the threaded portions of bolts 24 and 34 positioned at the inner circumferential ends of the elongated holes 22 and 32 of the respective small piece members 21 and 31. Figure 3 shows the coil bobbin 1 with the threaded portions of bolts 24 and 34 positioned at the outer circumferential ends of the elongated holes 22 and 32 of the respective small piece members 21 and 31. Therefore, the coil formed using the coil bobbin 1 in Figure 2 will have a larger inner diameter than the coil formed using the coil bobbin 1 in Figure 3. It is also possible to change the size of the winding section 4 so that the inner diameter of the coil falls between the two. Note that the inner circumferential ends of the elongated holes 22 and 32 refer to the ends on the intersection side of the two line segments in the sector shape shown in Figure 4 (the upper end in Figure 4), and the outer circumferential ends of the elongated holes 22 and 32 refer to the ends on the arc side in the sector shape shown in Figure 4 (the lower end in Figure 4).

After the individual small pieces 21 and 31 are fixed by the fixing parts 23 and 33, the coil windings can be wound around the multiple support members 41 of the winding section 4 to form the coil 10 as shown in Figure 5. This coil 10 may be used, for example, as a transmitting or receiving coil in contactless power transmission, or for other applications such as voltage transformation. Furthermore, when changing the diameter of the coil 10, the windings may be removed from the winding section 4 first, then the individual small pieces 21 and 31 may be moved radially, and then the windings may be wound around the winding section 4 again. Alternatively, the individual small pieces 21 and 31 may be moved radially while the windings are wound around the winding section 4. In the latter case, the individual small pieces 21 and 31 may be moved radially while increasing or decreasing the amount of windings wound around the winding section 4.

Furthermore, for example, when non-contact power transmission is performed at the joint portion of a robot arm using a coil formed with a coil bobbin 1, the central axis of the joint will be located on the central axis of the coil. In this case, the shaft member located on the central axis of the joint may pass through the through holes 24a, 34a of the bolts 24, 34.

As described above, with the coil bobbin 1 according to this embodiment, the size of the winding section 4 can be changed by moving the multiple small pieces 21, 31 of the first and second flange sections 2, 3 in the radial direction. Therefore, the inner diameter of the coil formed by winding wire around the winding section 4 can be changed using a single coil bobbin 1. Furthermore, when using the coil for contactless power transmission, the inner diameter of the coil can be prevented from changing by fixing the multiple small pieces 21, 31 with the fixing sections 23, 33. If it is desired to change the inner diameter of the coil, the fixing sections 23, 33 can be released, and the multiple small pieces 21, 31 can be moved radially to change the inner diameter of the coil. Additionally, because through holes 24a, 34a are formed on the central axes of the bolts 24, 34, when a coil formed using the coil bobbin 1 is used for contactless power transmission at the joint of a robot arm, the joint's axis member can pass through the through holes 24a, 34a.

Next, a modified example of the coil bobbin 1 according to this embodiment will be described.
[Stretchable tubular section]
As shown in Figure 6, the winding section 4 may further have an elastic cylindrical section 42 provided around a plurality of support members 41. The cylindrical section 42 preferably has enough elasticity to prevent slack between adjacent support members 41, regardless of the size of the winding section 4. The cylindrical section 42 may be a cylindrical member made of an elastic material such as rubber, a cylindrical woven or knitted fabric made of elastic fibers, or another cylindrical member with elasticity. The cylindrical section 42 may also be made of an insulating material, for example. When the winding section 4 has a cylindrical section 42, the coil winding will be wound around the outer circumference of the cylindrical section 42. Therefore, even if the winding loosens due to a change in the size of the winding section 4, for example, the loosened winding can be prevented from entering the center of the winding section 4, thus avoiding situations where the loosened winding is cut by getting caught on a support member 41 or other components.

[Expansion and contraction mechanism of the winding section]
The coil bobbin 1 may further include an expansion/contraction mechanism 5 that can expand or contract the diameter of the winding section 4 by moving a plurality of small piece members 21 of the first flange 2 in the radial direction, as shown in Figures 7 and 8. Expanding the diameter of the winding section 4 means that the length of the winding for one turn of the winding wound around the winding section 4 becomes longer, and contracting the diameter of the winding section 4 means that the length of the winding for one turn of the winding wound around the winding section 4 becomes shorter. In other words, when the diameter of the winding section 4 is expanded, the inner diameter of the coil becomes larger, and when the diameter of the winding section is contracted, the inner diameter of the coil becomes smaller.

Figures 7 and 8 are a front view and a top view of a coil bobbin 1 having an expansion/contraction mechanism 5. The expansion/contraction mechanism 5 shown in Figures 7 and 8 includes a plate-shaped member 51 arranged parallel to the first flange portion 2, and a plurality of rod-shaped members 52a to 52f, each having a first end rotatably connected to the plate-shaped member 51 and a second end rotatably connected to the outer circumference of the small piece member 21 of the first flange portion 2. For convenience, the rod-shaped members 52d and 52e are omitted from Figure 7. Figures 7 and 8 show the case where the plate-shaped member 51 is disc-shaped, but the plate-shaped member 51 may have other shapes, such as rectangular or polygonal. Furthermore, the material of the plate-shaped member 51 and the rod-shaped members 52 is not particularly limited, but insulating materials are preferred, for example, resin or ceramic.

The connection points between the first ends of the multiple rod-shaped members 52 and the plate-shaped member 51 are located on the circumference of a first circle 53 centered on the central axis of the coil formed using the coil bobbin 1, and the connection points between the second ends of the multiple rod-shaped members 52 and the first flange portion 2, that is, the connection points between the second ends of the multiple rod-shaped members 52 and the small piece members 21, are located on the circumference of a second circle 54 centered on the central axis of the coil. The diameter of the second circle 54 is larger than the diameter of the first circle 53. The first and second circles 53 and 54 are each located in a plane perpendicular to the central axis of the coil. The first ends of the rod-shaped members 52 may be rotatably supported relative to the plate-shaped member 51 by an axis extending tangentially to the first circle 53, as shown in Figure 7. Furthermore, the second end of the rod-shaped member 52 may be rotatably supported by an axis extending tangentially to the second circle 54 relative to the small piece member 21, as shown in Figures 7 and 8. Since the small piece members 21 of the first flange portion 2 do not strictly lie on the same plane, all the rod-shaped members 52 are of the same length. Therefore, to ensure that the rotation axes on the second end sides of the rod-shaped members 52 lie on the same plane, the axial lengths of the support portions provided on the small piece members 21 may differ, as shown in Figure 7.

In the expansion/contraction mechanism 5 configured as described above, the multiple small piece members 21 of the first flange 2 can be moved radially by changing the distance between the plate-shaped member 51 and the first flange 2, that is, the axial length of both. By bringing the plate-shaped member 51 closer to the first flange 2, the diameter of the winding portion 4 expands, and by moving the plate-shaped member 51 further away from the first flange 2, the diameter of the winding portion 4 shrinks. If each small piece member 21, 31 is only movable in a direction perpendicular to the axial direction, then the multiple small piece members 21 of the first flange 2 will be moved by the expansion/contraction mechanism 5, and similarly the multiple small piece members 31 of the second flange 3 will also be moved. During this movement, the nuts 25, 35 are loosened to allow each small piece member 21, 31 to move. Furthermore, even when the fixing portion 23 releases the multiple small piece members 21, the expansion/contraction mechanism 5 can restrict the movement of each small piece member 21 in the circumferential direction around the bolt 24. Also, as shown in Figure 7, the plate-shaped member 51 may have a through hole through which the threaded portion of the bolt 24 can pass. In this case, as shown in Figure 7, the diameter of the winding portion 4 can be restricted from shrinking by using a nut 26 to restrict the movement of the plate-shaped member 51 away from the first flange portion 2. Normally, the tension of the winding wire wound around the winding portion 4 causes a force that reduces the diameter of the winding portion 4, so it is sufficient to restrict only the reduction in the diameter of the winding portion 4. However, if it is also desired to restrict the expansion of the diameter of the winding portion 4 when no winding wire is wound around it, for example, the movement of the plate-shaped member 51 toward the first flange portion 2 may be restricted by another nut. A coil spring, with one end in contact with the plate-shaped member 51 side of the nut 25 and the other end in contact with the plate-shaped member 51 side of the plate-shaped member 51, and with the threaded portion of a bolt 24 passing through it, may be used to bias the plate-shaped member 51 toward the first flange portion 2, thereby restricting the movement of the plate-shaped member 51 toward the first flange portion 2. After the movement of the small pieces 21 and 31 by the expansion/contraction mechanism 5 is complete, the multiple small pieces 21 and 31 may be fixed by tightening nuts 25 and 35 onto bolts 24 and 34. However, if the distance between the first flange portion 2 and the plate-like member 51 remains constant after the movement of the small pieces 21 and 31, it is not necessary to fix the small pieces 21 with bolts 24 and nuts 25. Here, the case where the expansion/contraction mechanism 5 is provided only on the first flange portion 2 side has been described, but it goes without saying that a similar expansion/contraction mechanism may also be provided on the second flange portion 3 side.

[Cylindrical member with a cylindrical shape]
When the coil bobbin 1 has an expansion/contraction mechanism 5, as shown in Figure 9, the coil bobbin 1 may further include a cylindrical member 6 to cover the expansion/contraction mechanism 5. The cylindrical member 6 has a cylindrical side surface 6a and a bottom surface 6b provided at one end of the side surface 6a in the axial direction. The end of the side surface 6a opposite to the bottom surface 6b is open. The open end becomes the side of the first flange 2, and the cylindrical member 6 may be positioned so that the expansion/contraction mechanism 5 is located inside the cylindrical member 6. In this way, the expansion/contraction mechanism 5 can be protected. The central axis of the cylindrical member 6 is assumed to coincide with the central axis of the coil formed using the coil bobbin 1. By having such a cylindrical member 6, for example, the coil bobbin 1 can be detachably attached to the mounting target by fitting the cylindrical member 6 into a cylindrical recess provided on the mounting target. It is preferable that the recess has a shape and size that allows the cylindrical member 6 to be fitted into it.

The cylindrical member 6 may be detachably attached to, for example, the first flange portion 2, or to the expansion/contraction mechanism 5. The cylindrical member 6 may have a configuration (for example, a nut) on the inner surface of its bottom surface 6b that engages with the tip of the bolt 24, and may be attached to the bolt 24 using this configuration. If the bolt 24 has a through hole 24a, a through hole may also be provided in the bottom surface 6b. Preferably, the through hole in the bottom surface 6b coincides with the position of the through hole 24a when viewed from the axial direction. Furthermore, the inside of the cylindrical member 6 may be provided with a configuration that allows excess winding to be wound up. Even if the coil bobbin 1 does not have an expansion/contraction mechanism 5, the coil bobbin 1 may have a cylindrical member 6 provided on one end in the axial direction (for example, the side with the first flange portion 2). This is because the cylindrical shape of the cylindrical member 6 has the advantage of allowing it to be detachably attached to the object to be mounted. The material of the cylindrical member 6 is not particularly limited, but an insulating material is preferred, for example, resin or ceramic.

[Support member regulating member]
In this embodiment, the case in which multiple small piece members 21 and 31 are fixed by fixing parts 23 and 33 has been mainly described, but this is not required. Even if multiple small piece members 21 and 31 are not fixed, bolts 24 and 34 may be inserted into the elongated holes 22 and 32 of the small piece members 21 and 31, and nuts 25 and 35 may be screwed onto the bolts 24 and 34. However, in this case, the nuts 25 and 35 may be attached to the bolts 24 and 34 to the extent that the small piece members 21 and 31 are not fixed. If the small piece members 21 and 31 are not fixed by fixing parts 23 and 33, in order to prevent the diameter of the winding part 4 from shrinking due to the tension of the winding when the winding wire is wound around the winding part 4, the winding part 4 may have a removable restricting member 7 arranged inside the multiple support members 41 to prevent the diameter of the winding part 4 from shrinking, as shown in Figure 10. Figure 10 is a cross-section of the winding part 4 perpendicular to the axial direction.

The restricting member 7 is an annular member and is attached to the inner circumference of a plurality of support members 41 such that the central axis of the coil bobbin 1 is located at its center. As shown in Figure 10, a plurality of recesses into which the support members 41 are inserted may be formed on the outer circumference of the restricting member 7. These recesses may be arranged at equal intervals, for example. It is preferable that the restricting member 7 and the support members 41 are not fixed together. This is to facilitate the removal of the restricting member 7. It is also preferable that two or more restricting members 7 of the same size are arranged at different positions in the axial direction. This is to ensure that the diameter of the winding portion 4 does not differ in the axial direction. In this way, by attaching the restricting member 7, the size of the winding portion 4 can be kept constant even if the plurality of small piece members 21, 31 are not fixed by the fixing parts 23, 33. When changing the size of the winding portion 4, the attached restricting member 7 is removed from the support members 41, and a restricting member 7 corresponding to the changed size is attached. The material of the restricting member 7 is not particularly limited, but an insulating material is preferable, for example, resin or ceramic. Furthermore, to facilitate attachment and detachment, the restricting member 7 may be elastic.

[Modified support members]
In this embodiment, the case where the support member 41 is a rod-shaped member has been mainly described, but the shape of the support member 41 is not particularly limited. For example, the support member 41 may have an arc shape on the outer circumference in a cross section perpendicular to the longitudinal direction of the support member 41 that is convex toward the outer circumference. Figure 11 is a plan view of a coil bobbin 1 having such a support member 41. In Figure 11, the case in which the inner circumference in a cross section perpendicular to the axial direction of the support member 41 is also an arc shape that is convex toward the outer circumference is not shown, but this is not required. The inner circumference may also have an arc shape that is convex toward the inner circumference. In this case, the cross section perpendicular to the longitudinal direction of the support member 41 may be, for example, elliptical. By using a support member 41 of this shape, the coil formed by winding a wire around the winding section 4 becomes closer to a cylindrical shape, making it suitable, for example, as a coil used for contactless power transmission in the joint portion of a robot arm.

[Variations of Bolts]
In this embodiment, the case in which through holes 24a, 34a are formed on the central axis of the bolts 24, 34 has been mainly described, but this is not required. If a shaft member or the like does not need to pass through the center of the coil, the bolts 24, 34 do not need to have through holes 24a, 34a. Also, although the bolts 24, 34 usually have a fixed head and threaded portion, this is not required. The bolts 24, 34 may be composed of a member with only a threaded portion without a head (for example, a stud bolt), and a nut equivalent to a head that is screwed onto that member.

Furthermore, it goes without saying that the present invention is not limited to the embodiments described above, and various modifications are possible, all of which are also included within the scope of the present invention.

1 Coil bobbin 2 First flange 3 Second flange 4 Winding section 5 Expanding/contracting mechanism 6 Cylindrical members 21, 21a-21f, 31, 31a-31f Small piece members 23, 33 Fixing parts 24, 34 Bolts 25, 26, 35 Nuts 41, 41a-41f Support member 42 Cylindrical section 51 Plate-shaped members 52, 52a-52f Rod-shaped members

Claims (6)

A coil bobbin around which a winding is wound,
First and second flanges provided at both ends in the axial direction of the coil formed by winding the wire,
It comprises a winding section provided between the first and second flanges, around which the winding wire is wound,
The first and second flange portions each have a plurality of small piece members that are movably provided in the radial direction,
The winding portion has a plurality of support members extending in the axial direction of the coil, with both ends fixed to a plurality of small piece members having the first flange portion and a plurality of small piece members having the second flange portion, respectively.
The invention further comprises an expansion/contraction mechanism that can expand or contract the diameter of the winding portion by moving a plurality of small piece members of the first flange portion radially, which are arranged on the side of the first flange portion opposite to the winding portion.
The aforementioned expansion/contraction mechanism is
A plate-shaped member arranged parallel to the first flange portion,
The plate-shaped member has a first end that is rotatably connected to it, and a plurality of rod-shaped members have a second end that is rotatably connected to the outer circumference of the small piece member of the first flange portion.
The connection points between the first ends of the plurality of rod-shaped members and the plate-shaped member are located on the circumference of a first circle centered on the central axis of the coil.
The connection points between the second ends of the plurality of rod-shaped members and the first flange portion are located on the circumference of a second circle, which has a larger diameter than the first circle and is centered on the central axis of the coil.
A coil bobbin in which the distance between the plate-like member and the first flange can be changed to move the plurality of small pieces of the first flange radially . The coil bobbin according to claim 1, wherein the support member is a rod-shaped member. The coil bobbin according to claim 1, wherein the outer circumference of the cross-section perpendicular to the longitudinal direction of the support member has a circular arc shape that is convex toward the outer circumference. The winding portion further comprises an expandable cylindrical portion provided around the plurality of support members,
The coil bobbin according to any one of claims 1 to 3, wherein the winding is wound around the outer circumference of the cylindrical portion. The aforementioned small piece member is provided with an elongated hole extending in the radial direction.
The coil bobbin according to any one of claims 1 to 4, wherein the first and second flange portions each further have a fixing portion that releasably fixes the plurality of small piece members by a bolt having a through hole formed on its central axis and a nut that is screwed onto the bolt, which is inserted into each of the elongated holes of the plurality of small piece members. The expansion and contraction mechanism is further comprised of a cylindrical member with a cylindrical shape covering it.
The coil bobbin according to any one of claims 1 to 5, wherein the central axis of the cylindrical member coincides with the central axis of the coil.