Transformer and method for manufacturing transformer

Abstract

To provide a transformer which can be reduced in size while securing the shape of a coil by adopting a bobbin in a part and an insulating sheet in a core winding part, and to provide a method of manufacturing the same.SOLUTION: A transformer 10 according to the present invention includes a coil assembly 65 including a coil 20 formed by winding a coated wire 21 in a rounded quadrangular shape so as to have right and left straight portions 2222 facing each other, an upper connecting portion 23a connecting upper ends of the straight portions, and a lower connecting portion 23b connecting lower ends of the straight portions, an upper bobbin side 30a having a recessed groove 31 covering an inner peripheral surface and a side surface of the upper connecting portion, and a lower bobbin side 30b having a recessed groove covering an inner peripheral surface and a side surface of the lower connecting portion. The stator includes an insulating sheet 40 wound around the linear part of the coil, and a core 50 composed of a directional electromagnetic steel plate 51 and spirally wound from above the insulating sheet.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a transformer having a coil wound with a grain-oriented electromagnetic steel sheet in a roll shape with an insulating sheet interposed therebetween, and to a method for manufacturing the same. [Background technology]

[0002] Known transformers for voltage and current transformation include a cylindrical core wound around a coil wound in a roughly rounded rectangular shape. For example, the transformer disclosed in Patent Document 1 has a coil made by winding a coated wire in a roughly rectangular shape around an electrically insulating resin bobbin, and a core made of grain-oriented electromagnetic steel sheet wound around the bobbin. The transformer disclosed in Patent Document 2 has an insulating sheet wound around a roughly rounded rectangular coil, and a grain-oriented electromagnetic steel sheet coil wound around the insulating sheet. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 8-51034 [Patent Document 2] Patent No. 7442885 Summary of the Invention [Problem to be solved by the invention]

[0004] The transformer in Patent Document 1 uses a bobbin with a rounded rectangular shape and grooves formed on the outer periphery to ensure coil winding, insulation, and creepage distance. Because the resin bobbin is a molded resin product, its thickness must be 0.8 mm to 1.5 mm to ensure strength and insulation heat resistance. In other words, the radial thickness of the resin bobbin is 1.6 mm to 3.0 mm. A thicker resin bobbin directly leads to a larger transformer. If the transformer size is specified, the diameter of the coated wire used in the coil must be reduced by the thickness of the resin bobbin, resulting in increased loss due to temperature rise and increased voltage fluctuation characteristics.

[0005] The transformer of Patent Document 2 does not use a bobbin, but winds the coil in a roughly rounded rectangular shape, and insulates the coil from the core with an insulating sheet wrapped around the straight portion of the coil. However, when winding a thin coated wire, such as that used in a transformer with a capacity of 1 kVA or less, it is extremely difficult to wind the wire regularly and in an orderly manner without breaking the winding. Furthermore, it is not possible to provide taps in the coil.

[0006] An object of the present invention is to provide a transformer and a manufacturing method thereof that can be made smaller while maintaining the coil shape by using insulating sheets in some parts around the bobbin and core. [Means for solving the problem]

[0007] The transformer according to the present invention comprises: a coil formed by winding a coated wire in a rounded rectangular shape to have opposing left and right straight portions, an upper connecting portion connecting the upper ends of the straight portions, and a lower connecting portion connecting the lower ends of the straight portions; an upper bobbin having a recessed groove formed therein that covers the inner circumferential surface and side surface of the upper connecting portion; and a lower bobbin having a recessed groove formed therein that covers the inner circumferential surface and side surface of the lower connecting portion; an insulating sheet having electrical insulation properties and wound around the straight portion of the coil; a core made of grain-oriented electromagnetic steel sheet and wound spirally around the insulating sheet; It is equipped with.

[0008] It is desirable that the upper and lower bobbins have creepage distance securing projections protruding from their inner peripheries for positioning the core.

[0009] At least one of the upper bobbin and the lower bobbin is preferably formed on a side surface thereof with a tap lead-out portion through which a tap led out from a coil passes.

[0010] The transformer is a current transformer, A conductor wound on the insulating sheet side between the insulating sheet and the core, and a second insulating sheet wound between the conductor and the core; It can have the following.

[0011] Further, a method for manufacturing a coil assembly according to the present invention includes the steps of: A method for manufacturing a coil assembly including: a coil formed by winding a coated wire into a rounded rectangular shape so as to have opposing left and right straight portions, an upper connecting portion connecting upper ends of the straight portions, and a lower connecting portion connecting lower ends of the straight portions; an upper bobbin having a recessed groove formed therein that covers an inner peripheral surface and a side surface of the upper connecting portion; and a lower bobbin having a recessed groove formed therein that covers an inner peripheral surface and a side surface of the lower connecting portion, preparing the upper bobbin and the lower bobbin, a pair of side jigs each having a linear groove formed on the outer periphery thereof, a side spacer jig for holding the pair of side jigs at a predetermined distance, and a pair of bobbin spacer jigs for holding the upper bobbin and the lower bobbin at a predetermined distance; The upper bobbin is disposed above the side spacer jig so that the groove faces upward, the lower bobbin is disposed below the side spacer jig so that the groove faces downward, the side jigs are disposed on the left and right sides of the side spacer jig so that the groove faces outward, and the bobbin spacer jigs are attached to the front and rear of the side spacer jig so that the upper bobbin and the lower bobbin are spaced a predetermined distance apart, thereby forming a bobbin-jig assembly; a covered wire is hooked onto any one of the upper bobbin, the lower bobbin, and the side jig, and the bobbin-jig assembly is rotated around the left-right and top-bottom centers of the side spacer jig as a rotation center, thereby winding the covered wire around the grooves of the upper bobbin, the lower bobbin, and the side jig to form a coil; After the coil is formed, the rotation of the bobbin-jig assembly is stopped, and one of the bobbin spacer jigs and the side spacer jigs is removed. Then, the other bobbin spacer jig is left in place, and the side jig is removed, thereby obtaining the coil assembly.

[0012] The method for manufacturing a transformer of the present invention includes the steps of: After winding an insulating sheet around the straight portion of the coil assembly manufactured as described above, the other bobbin spacer jig is removed. A core made of a grain-oriented electromagnetic steel sheet is spirally wound around the insulating sheet.

[0013] Further, the method for manufacturing a transformer of the present invention includes the steps of: After winding an insulating sheet having electrical insulation properties around the straight portion of the coil assembly manufactured as described above, the other bobbin spacer jig, the upper bobbin, and the lower bobbin are removed; A core made of a grain-oriented electromagnetic steel sheet is spirally wound around the insulating sheet.

[0014] The transformer is a current transformer, After the insulating sheet is wound, and before the core is wound, a conductor is wound on the insulating sheet, and then a second insulating sheet is wound on top of the conductor. [Effects of the Invention]

[0015] According to the transformer and the manufacturing method of the present invention, the straight portion of the coil where the core is wound can be made of only insulating sheet. In addition, the upper connecting portion of the coil is housed in the groove of the upper bobbin, and the lower connecting portion is housed in the groove of the lower bobbin, so the coil will not come apart, and taps can be easily provided. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a perspective view of a transformer according to one embodiment of the present invention. [Figure 2] FIG. 2 is an exploded front view of the bobbin and jig assembly. [Figure 3] FIG. 3 is an exploded right side view of the bobbin and jig assembly. [Figure 4] FIG. 4 is a perspective view of the bobbin and jig assembly. [Figure 5] FIG. 5 is a front view showing a state in which a coil is wound around the bobbin and jig assembly. [Figure 6] FIG. 6 is a front view showing a state in which one bobbin spacer jig, a side spacer jig, and a side jig have been removed from the bobbin-jig assembly. [Figure 7] FIG. 7 is a front view of the coil with an insulating sheet wound around the straight portion thereof. [Figure 8] 8A and 8B are cross-sectional views of the coil taken along line EE in FIG. 7, in which (a) is a cross-sectional view of the coil during winding of the insulating sheet, and (b) is a cross-sectional view of the coil after the insulating sheet has been wound tightly. [Figure 9] FIG. 9 is a front view showing a state in which the other bobbin spacer jig has been removed. [Figure 10] FIG. 10 is a front view of the transformer obtained by winding the core. [Figure 11] FIG. 11 is an end view of a bobbin made up of bobbin segments, where (a) shows the bobbin segments joined together, and (b) shows the bobbin segments separated from each other. [Figure 12] FIG. 12 is a front view of the bobbinless transformer. [Figure 13] FIG. 13 is an end view of the bobbin of a two-phase winding transformer. [Figure 14] FIG. 14 is a side view of a side jig for a two-phase winding transformer. [Figure 15] Figure 15 is an end view of an embodiment in which the side jig of a two-phase winding transformer is composed of side jig segments, where (a) shows the side jig segments integrated together, and (b) shows the side jig segments disconnected from each other. [Figure 16] FIG. 16 is a perspective view of the primary-side insulating sheet and the secondary-side insulating sheet. [Figure 17] FIG. 17 is a cross-sectional view showing a state in which an insulating sheet is wound around the primary coil and the secondary coil of a two-phase winding transformer. [Figure 18] FIG. 18 is a perspective view of a current transformer in the process of being manufactured, in which conductors are arranged on an insulating sheet. [Figure 19] FIG. 19 is a perspective view showing the state in which the conductor is wound. [Figure 20]FIG. 20 is a cross-sectional view of the current transformer taken perpendicular to the straight portion. [Figure 21] FIG. 21 is a perspective view of a current transformer according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0017] A transformer 10 according to one embodiment of the present invention will be described below with reference to the drawings. For ease of understanding, in this specification and the drawings, the upper bobbin 30a at the front side of the transformer 10 in FIG. 1 will be referred to as the "upper" and the lower bobbin 30b at the rear side will be referred to as the "lower." In other words, the upper side of the front view in FIG. 10 will be referred to as the "upper" and the lower side as the "lower," and the left side in FIG. 10 will be referred to as the "left," the right side as the "right," the front side as the "front," and the rear side as the "rear." Of course, these directions are used for the purpose of explanation and do not specify the direction or manner of use of the transformer 10.

[0018] <Overall overview of Transformer 10> 1 is a perspective view of a transformer 10 according to one embodiment of the present invention. The transformer 10 is, for example, a power transformer, and is configured by disposing a cylindrical core 50 in which grain-oriented electromagnetic steel sheet 51 is spirally wound around the outer periphery of a coil 20 wound in a rounded rectangular shape, with an insulating sheet 40 interposed therebetween. Reference numerals 30a and 30b denote upper and lower bobbins that hold connecting portions 23a and 23b of the coil 20.

[0019] <Coil 20> The coil 20 constituting the transformer 10 can be, for example, a single-phase winding in which the primary and secondary coils share a portion, and is formed by winding a coated wire 21 such as an enameled copper wire with an insulating coating. A two-phase winding in which the primary and secondary coils are separate coils will be described in a modified example, but the primary and secondary coils can be wound with insulation between them. The coil 20 can be wound into a substantially rounded rectangle with opposing straight portions 22, 22, as shown in Figures 5 and 6, which will be described later. The straight portions 22, 22 are the portions around which the insulating sheet 40, as shown in Figures 7 and 9, and the core 50, as shown in Figures 1 and 10, are wound. 1, the straight portions 22, 22 are connected by rounded connecting portions 23a, 23b (upper connecting portion and lower connecting portion), but the arc shape, curvature, and curvature radius of the corners of connecting portions 23a, 23b are not limited to this as long as they are rounded, and the space between the corners may be arc-shaped, elliptical, or linear. In this specification, this type of coil 20 shape is also referred to as a rounded rectangle.

[0020] <Upper bobbin 30a, lower bobbin 30b> The coil 20 has an upper bobbin 30a and a lower bobbin 30b mounted on the connecting portions 23a and 23b, which face each other from the inside. The upper bobbin 30a and the lower bobbin 30b are made of electrically insulating resin, and as best shown in FIGS. 1 to 4, particularly FIG. 4, a groove 31 is formed inward from the outer periphery. The groove 31 is a groove that covers the inner periphery and side surfaces of the connecting portions 23a and 23b of the coil 20. The groove 31 has a pair of front and rear lateral walls 32, 32 that form the side surfaces, and a bottom wall 33 that forms the bottom surface 34 of the groove 31. It is desirable that the groove 31 have a cross-section that tapers toward the bottom surface so that the coil 20 can be wound in a shape that is close to a circular cross-section. In this embodiment, as shown in FIG. 3, the groove 31 is an isosceles trapezoid (half of a hexagon) whose width tapers toward the bottom surface 34.

[0021] The upper bobbin 30a and the lower bobbin 30b have tap lead-out portions 35 formed on the side walls 32, through which the taps 24 drawn out from the coils 20 pass. The illustrated tap lead-out portions 35 are notched recesses formed in the side walls 32.

[0022] Additionally, the upper bobbin 30a and the lower bobbin 30b have a creepage distance ensuring protrusion 36 protruding from the bottom wall 33 to position the core 50 on the side opposite the recessed groove 31 and ensure a creepage distance with the coil 20. Specifically, the end face of the core 50 abuts against the creepage distance ensuring protrusion 36 to position the core 50 on the straight portion 22 of the coil 20 and maintain a constant distance to the edge of the insulating sheet 40 wound around the straight portion 22. As best shown in FIG. 2 , the creepage distance ensuring protrusion 36 is a U-shaped protrusion in cross section that has a hollow claw insertion hole 37 protruding from the center of the bottom wall 33. The claw insertion hole 37 is formed in the creepage distance ensuring protrusion 36 because, in this embodiment, it also serves as an attachment portion for attaching bobbin spacer jigs 70a, 70b used when winding the coil 20.

[0023] <Insulation sheet 40> As shown in Figures 1, 7, 9, and 10, an insulating sheet 40 is wrapped around the straight portions 22, 22 of the coil 20. The insulating sheet 40 insulates the coil 20 from the core 50. As shown in the cross-sectional view of Figure 8, the insulating sheet 40 is a thin sheet made of an electrically insulating material. For example, the insulating sheet 40 can be made of aramid paper (Nomex (registered trademark) manufactured by DuPont) woven with aramid fibers made of aromatic polyamide resin, or polyester film.

[0024] The insulating sheet 40 is formed to have a width that allows it to be wound around the straight portion 22 and is at least wider than the grain-oriented electromagnetic steel plate 51 that constitutes the core 50. In order to ensure a creepage distance between the coil 20 and the core 50, it is desirable that the width of the insulating sheet 40 is at least 5 mm (2.5 mm on one side) longer than the width of the grain-oriented electromagnetic steel plate 51. Furthermore, in order to provide an insulating effect, the length of the insulating sheet 40 is such that it wraps around the outer periphery of the straight portion 22 at least once, preferably 1.2 to 2 times.

[0025] After the insulating sheet 40 is wrapped around the straight portion 22, it is preferable to fasten it with a fixing means such as tape (not shown) to prevent it from coming undone.

[0026] As will be described later, during the process of assembling the transformer 10, after the coil 20 is wound (FIGS. 5 and 6), the upper and lower bobbins 30a and 30b are held at a predetermined distance by the bobbin spacer jigs 70a and 70b until the insulating sheet 40 is wound. This prevents the straight portion 22 of the coil 20 from bending or loosening. Therefore, the insulating sheet 40 is wound around the straight portion 22 with the bobbin spacer jigs 70a and 70b still attached. On the other hand, when winding the core 50, the bobbin spacer jigs 70a and 70b must be removed. At this time, the straight portion 22 of the coil 20 must be reinforced by the insulating sheet 40 to prevent the straight portion 22 from bending or loosening. Therefore, the insulating sheet 40 must have a predetermined strength. For this reason, the insulating sheet 40 preferably has a thickness of 0.1 mm to 0.5 mm, and more preferably 0.2 mm to 0.4 mm.

[0027] <Core 50> A core 50 is formed on the insulating sheet 40 that is wound around the straight portion 22 of the coil 20. The core 50 is formed by winding a grain-oriented electromagnetic steel sheet 51 in a spiral shape around the insulating sheet 40, as shown in Fig. 1. It is desirable to perform an annealing heat treatment on the grain-oriented electromagnetic steel sheet 51 in advance.

[0028] The transformer 10 configured as described above does not require a bobbin on the straight portion 22, and can be made smaller by directly winding the insulating sheet 40 and the core 50. On the other hand, the shape of the coil 20 can be secured by attaching an upper bobbin 30a to the upper connecting portion 23a and a lower bobbin 30b to the lower connecting portion 23b.

[0029] <Manufacturing method> The transformer 10 of the present invention can be fabricated according to FIGS.

[0030] FIG. 2 shows the upper bobbin 30a, the lower bobbin 30b, and jigs 70, 80, and 90 for winding the coil 20 between the upper bobbin 30a and the lower bobbin 30b.

[0031] The jigs include side jigs 90, 90 around which the coil 20 is wound, a side spacer jig 80 that holds the side jigs 90, 90 at a predetermined distance, and bobbin spacer jigs 70 (70a, 70b) that hold the bobbins 30a, 30b at a predetermined distance.

[0032] <Side jig 90> 3 and 4, the side jig 90 has a linear groove 91 formed on the outer periphery. The groove 91 is continuous with the grooves 91 of the upper bobbin 30a and the lower bobbin 30b, and the covered wire 21 of the coil 20 is wound around the groove 91. The cross-sectional shape of the groove 91 can be the same as the cross-sectional shape of the grooves 31 of the upper bobbin 30a and the lower bobbin 30b.

[0033] When winding the coil 20, the side jigs 90 are attached to the left and right sides of the side spacer jig 80 as shown in Figures 4 and 5. On the inner periphery of the side jig 90, attachment pieces 92 for attachment to the side spacer jig 80 are formed to protrude in the front-to-rear direction, and fastening holes 93 are opened in the attachment pieces 92.

[0034] <Side spacer jig 80> The side spacer jig 80 is a jig that holds the side jigs 90 at a predetermined interval. The side spacer jig 80 has a roughly rectangular parallelepiped shape that is thicker than the upper bobbin 30a and the lower bobbin 30b. The side spacer jig 80 has screw holes (not shown) formed on its side surfaces for screwing the side jig 90. The side spacer jig 80 also has rotating shaft mounting holes 81 formed in the left-right and top-bottom central portions when viewed from the front. The illustrated rotating shaft mounting hole 81 is a grooved hole into which a rotating shaft 100 (e.g., with a key) of a motor as shown in FIG. 4 fits when winding the coil 20.

[0035] <Bobbin spacer jig 70 (70a, 70b)> The bobbin spacer jig 70 is a jig that holds the upper bobbin 30a and the lower bobbin 30b at a predetermined distance, and also integrates the bobbins 30a, 30b with the side jig 90 and the side spacer jig 80 to form the bobbin-jig assembly 60.

[0036] 2 to 4, the bobbin spacer jig 70 is a jig with bobbin locking claws 73 protruding inward. In the illustrated embodiment, the jig has a rectangular parallelepiped jig body 71 to which an L-shaped metal fitting 72 having the bobbin locking claws 73 is attached. The jig body 71 and the L-shaped metal fitting 72 are fastened with screws 74.

[0037] The jig body 71 has a rotary shaft mounting hole 75 formed in the center thereof, which is aligned with the rotary shaft mounting hole 81 of the side spacer jig 80 .

[0038] <Bobbin and jig assembly 60> As shown in FIG. 2A, the bobbins 30a, 30b and jigs 70, 80, 90 configured as described above are attached by screwing the side jig 90 close to both sides of the side spacer jig 80 with the grooves 91 facing outward. As shown in FIG. 3, the upper bobbin 30a is positioned with the grooves 31 facing upward and the lower bobbin 30b with the grooves 31 facing downward. The bobbins 30a, 30b are then brought close to the side spacer jig 80 from above and below as indicated by arrow B. The bobbin spacer jigs 70a, 70b are then brought close to the side spacer jig 80 from the front and rear as indicated by arrow C, and the bobbin locking claws 73 of the bobbin spacer jigs 70a, 70b are inserted into the claw insertion holes 37 (see FIG. 2) of the bobbins 30a, 30b as indicated by arrow D. This completes the bobbin-jig assembly 60 shown in FIG. 4.

[0039] As shown in FIGS. 2 to 4, the bobbin-jig assembly 60 has a configuration in which the recessed grooves 31 of the bobbins 30a, 30b and the recessed grooves 91 of the side jigs 90, 90 are continuous in the circumferential direction.

[0040] <Winding of coil 20> As shown in Fig. 4, the motor shaft 100 is inserted into the aligned shaft mounting holes 75, 81 of the obtained bobbin-jig assembly 60. The coated wire 21 is wound on a reel or the like, and one end 25a is pulled out from the tap pull-out portion 35 of the upper bobbin 30a (or the lower bobbin 30b) and hooked into the recessed groove 31, for example, as shown in Fig. 5.

[0041] From this state, by driving the motor, the bobbin / jig assembly 60 rotates around the rotary shaft mounting holes 75, 81 as the center of rotation, and the covered wire 21 is wound into the recessed grooves 31, 91. If the covered wire 21 needs to be tapped during the winding, the rotation of the bobbin / jig assembly 60 is stopped, the tap is formed, and the covered wire 21 is pulled out from the tap pull-out portion 35. Then, when the coil 20 has been wound a predetermined number of times, the rotation of the bobbin / jig assembly 60 is stopped, the covered wire 21 is cut, and the end 25b of the coil 20 is hooked onto the tap pull-out portion 35 as shown in FIG. 5. The bobbin / jig assembly 60 is then removed from the rotary shaft 100 of the motor. This completes the coil 20 winding process. The portion of the coil 20 that fits into the groove 91 of the side jig 90 is the straight portion 22, and the portions that fit into the grooves 31 of the bobbins 30a, 30b are the upper connecting portion 23a that connects the upper ends of the straight portions 22, 22, and the lower connecting portion 23b that connects the lower ends of the straight portions 22, 22.

[0042] <Removing jigs 70, 80, and 90> As shown in Figure 6, some of the jigs 70, 80, and 90 are removed from the bobbin-jig assembly 60 (Figure 5) on which the coil 20 has been wound. Specifically, one of the bobbin spacer jig 70a (the rear jig in Figure 6) is left, and the other jigs 70b, 80, and 90 are removed. The reason for leaving one of the bobbin spacer jig 70a is to hold the upper bobbin 30a and the lower bobbin 30b at a predetermined distance and to prevent the straight portion 22 of the coil 20 from bending or sagging until the insulating sheet 40 is wound around it.

[0043] The order of removing the jigs is as follows: first, pull out the front bobbin spacer jig 70b towards you. Next, release the screws connecting the side spacer jig 80 and side jig 90, and pull out the side spacer jig 80 towards you. Then, for the left and right side jigs 90, shift the right side jig 90 to the left and pull it out towards you. Similarly, shift the left side jig 90 to the right and pull it out towards you. This results in a coil assembly 65 in which the upper bobbin 30a and lower bobbin 30b are held at a predetermined distance by the rear bobbin spacer jig 70a, as shown in Figure 6.

[0044] <Wrapping of insulating sheet 40> As shown in FIG. 7, an insulating sheet 40 is wound around the straight portion 22 of the coil 20 of the coil assembly 65 of FIG. 6. As shown in FIG. 7, the insulating sheet 40 is wound as far as possible so that it protrudes above or below the creepage distance securing protrusions 36 protruding inward from the bobbins 30a, 30b. As a result, when the core 50 is wound around the insulating sheet 40, an end of the insulating sheet 40 protrudes from the core 50, forming a protruding portion 41 (see FIG. 10), which corresponds to the creepage distance. After the winding is complete, one end of the insulating sheet 40 is attached to the straight portion 22 of the coil 20 with a fixing means such as tape, and the insulating sheet 40 is wound one or more times as shown in FIG. 8(a). Then, the insulating sheet 40 is tightened as shown by arrow F, applying tension so that the cross section of the straight portion 22 of the coil 20 approaches a substantially circular shape, as shown in FIG. 8(b). After the free end of the insulating sheet 40 is fixed with a fixing means such as tape. As shown in FIG. 8, insulating sheets 40 are wrapped around both straight portions 22, 22, respectively.

[0045] <Removing the rear bobbin spacer jig 70a> By attaching the insulating sheet 40, the straight portion 22 is reinforced and prevented from bending or loosening. Therefore, in this state, the rear bobbin spacer jig 70a remaining on the coil assembly 65 can be removed. Even after the bobbin spacer jig 70a is removed, the strength of the insulating sheet 40 keeps the straight portion 22 in a straight state, as shown in Figure 9.

[0046] <Core 50 winding> Finally, a grain-oriented electromagnetic steel sheet 51 is wound around the insulating sheet 40. The grain-oriented electromagnetic steel sheet 51 can be wound, for example, as described in Patent Document 2, but the method is not limited to this. The core 50 formed by winding the grain-oriented electromagnetic steel sheet 51 is wound so that its end faces abut against the creepage distance securing protrusions 36, 36 protruding inward from the bobbins 30a, 30b, as shown in Figures 1 and 10. This prevents the core 50 from protruding beyond the creepage distance securing protrusions 36, 36, and therefore ensures that the protruding portion 41 of the insulating sheet 40 serves as the creepage distance for insulation.

[0047] After the winding of the grain-oriented electromagnetic steel sheet 51 is completed, the end of the grain-oriented electromagnetic steel sheet 51 may be fixed to the peripheral surface of the core 50 by welding or the like. Figures 1 and 10 show the manufactured transformer 10.

[0048] The transformer 10 of the present invention employs bobbins 30a and 30b in some parts, but employs insulating sheet 40 instead of a bobbin for the portion around which core 50 is wound. This allows the shape of coil 20 to be maintained by bobbins 30a and 30b, while core 50 is wound around the portion where there is no bobbin, thereby enabling core 50 to be made smaller. This allows the transformer 10 to be made smaller.

[0049] <Modification> Modifications of the present invention will now be described.

[0050] <Transformer 10 without bobbins 30a and 30b> In the above embodiment, the bobbins 30a and 30b remain in the final transformer 10 (FIG. 10). However, the bobbins 30a and 30b can be removed during manufacturing. For example, in FIG. 11, the bobbins 30a and 30b are configured to be separable into left and right halves (reference numerals 39a and 39b). The left and right bobbin segments 39a and 39b can be integrated with bolts or the like. The bobbins 30a and 30b formed by integrating the left and right bobbin segments 39a and 39b are used to carry out the insulating sheet winding process shown in FIG. 7. Then, after removing the bobbin spacer jig 70a as shown in FIG. 9, the bobbin segments 39a and 39b are disconnected from each other and removed from the coil 20 as shown in FIG. 12. As described above, the straight portion 22 of the coil 20 maintains its straight state due to the strength of the insulating sheet 40, so that the coil 20 of the coil assembly 65 maintains its rounded rectangular shape as shown in FIG.

[0051] Thereafter, the core 50 may be wound as shown in Fig. 10. After the core 50 is wound, the bobbins 30a and 30b may be removed.

[0052] According to this embodiment, the bobbins 30a and 30b do not remain in the transformer 10, which allows for a smaller and lighter transformer 10. Furthermore, since the bobbin segments 39a and 39b do not remain in the transformer 10, they do not need to be electrically insulating and can be made of, for example, metal and reused.

[0053] <Two-phase winding transformer> In the case where the primary coil 20a and the secondary coil 20b are two-phase windings of separate coils (see FIG. 17), as shown in FIG. 13, the bobbins 30a and 30b have an insulating wall 38 protruding from the bottom surface 34 of the groove 31, dividing the groove 31 in half (31a and 31b). Similarly, as shown in FIGS. 14 and 15, the side jig 90 also has an insulating wall 94 protruding from the groove 91, dividing the groove 91 in half (91a and 91b). In FIGS. 14 and 15, the side jig 90 can also be divided into left and right halves (90a and 90b). Then, the bobbin-jig assembly 60 is assembled using the bobbins 30a and 30b and the side jigs 90, 90 so that the grooves 31a and 91a are aligned.

[0054] In the bobbin-jig assembly 60, the primary coil 20a is wound in one of the grooves 31a, 91a, and the secondary coil 20b is wound in the other grooves 31b, 91b. Then, as shown in FIG. 5, after the coil 20 is wound, the bobbin spacer jig 70b and the side spacer jig 80 are removed, leaving the bobbin spacer jig 70a. The side jigs 90, 90 are also removed. In this embodiment, the side jig 90 is made up of side jig segments 90a, 90b that can be separated into left and right halves, so it is sufficient to remove them one by one.

[0055] For example, the insulating sheet 40 wrapped around the straight section 22 may also employ a primary side insulating sheet 40a and a secondary side insulating sheet 40b bent into an approximately U-shape, as shown in Figure 16. First, remove the side jig segment 90a, insert one end of the primary side insulating sheet 40a into the resulting gap, remove the side jig segment 90b, and insert one end of the secondary side insulating sheet 40b into the resulting gap (see Figure 17).

[0056] 17, the primary coil 20a is wrapped with the primary insulating sheet 40a, the secondary coil 20b is wrapped with the secondary insulating sheet 40b, and the entire assembly is then covered with the insulating sheet 40c from the outside. This achieves insulation between the primary coil 20a and the secondary coil 20b. After that, the bobbin spacer jig 70a is removed and the core 50 is wound using the same procedure as in FIGS. 9 and 10.

[0057] The bobbins 30a and 30b in FIG. 13 can be separated into left and right halves as in FIG. 11, so that they can be removed from the coil assembly 65, thereby obtaining a two-phase winding transformer 10 without a bobbin.

[0058] <Current Transformer 110> The transformer 10 described above is a power transformer. However, a current transformer 110 can also be fabricated in a similar manner by interposing an insulated conductor 111 between the coil 20 and the core 50 so as to encase the coil 20. The conductor 111 is, for example, a copper plate, and as shown in FIG. 18, has a generally U-shaped cross section, with terminals 112 formed on its edge as lead wires. After winding the insulating sheet 40 around the coil 20 as shown in FIG. 9, the conductor 111 is fitted to encase the coil 20 as shown in FIG. 18 (insulating sheet 40 is not shown), and the tip of the conductor 111 is bent to fit the coil 20 as shown in FIGS. 19 and 20. The tips of the conductors 111 are spaced slightly apart to create a gap 113 as shown in FIG. 20. Then, a second insulating sheet 42 (not shown in FIG. 21) is wound around the outer periphery of the conductor 111 as shown in FIG. 20, and the core 50 is then wound around it as shown in FIGS. 20 and 21. The current transformer 110 having this configuration can be used in various power supply devices, such as wireless power supply devices that transmit power at high frequencies, and power supply devices that transfer power charged in a storage battery from a solar panel between an electric vehicle and a home.

[0059] The current transformer 110 may have a configuration without the bobbins 30a and 30b described above.

[0060] The above description is for the purpose of explaining the present invention, and should not be construed as limiting the invention described in the claims or narrowing its scope. Furthermore, the configuration of each part of the present invention is not limited to the above embodiment, and various modifications are possible within the technical scope described in the claims. [Explanation of symbols]

[0061] 10 Transformer 20 coils 21 Covered wire 22 Straight section 23a Upper connection part 23b Lower connection part 30a upper bobbin 30b Lower bobbin 31 Groove 36 Creepage distance securing protrusion 37 Nail insertion hole 40 Insulation sheet 50 cores 51 Grain-oriented electrical steel sheet 60 Jig assembly 65 Coil assembly 70(70a, 70b) Bobbin spacer jig 73 Bobbin locking claw 80 Side spacer jig 90 Side jig 91 Groove 110 Current transformer

Claims

1. a coil formed by winding a coated wire in a rounded rectangular shape to have opposing left and right straight portions, an upper connecting portion connecting the upper ends of the straight portions, and a lower connecting portion connecting the lower ends of the straight portions; an upper bobbin having a recessed groove formed therein that covers the inner circumferential surface and side surface of the upper connecting portion; and a lower bobbin having a recessed groove formed therein that covers the inner circumferential surface and side surface of the lower connecting portion; an insulating sheet having electrical insulation properties and wound around the straight portion of the coil; a core made of grain-oriented electromagnetic steel sheet and wound spirally around the insulating sheet; A transformer comprising:

2. The upper bobbin and the lower bobbin have creepage distance securing protrusions protruding from their inner peripheries to position the core. The transformer according to claim 1 .

3. At least one of the upper bobbin and the lower bobbin has a tap lead-out portion formed on a side surface thereof through which a tap led out from a coil passes. The transformer according to claim 2 .

4. The transformer is a current transformer, a conductor wound around the insulating sheet between the insulating sheet and the core, and a second insulating sheet wound between the conductor and the core; 4. The transformer according to claim 1, further comprising:

5. A method for manufacturing a coil assembly including: a coil formed by winding a coated wire into a rounded rectangular shape so as to have opposing left and right straight portions, an upper connecting portion connecting upper ends of the straight portions, and a lower connecting portion connecting lower ends of the straight portions; an upper bobbin having a recessed groove formed therein that covers an inner peripheral surface and a side surface of the upper connecting portion; and a lower bobbin having a recessed groove formed therein that covers an inner peripheral surface and a side surface of the lower connecting portion, preparing the upper bobbin and the lower bobbin, a pair of side jigs each having a linear groove formed on the outer periphery thereof, a side spacer jig for holding the pair of side jigs at a predetermined distance, and a pair of bobbin spacer jigs for holding the upper bobbin and the lower bobbin at a predetermined distance; The upper bobbin is disposed above the side spacer jig so that the groove faces upward, the lower bobbin is disposed below the side spacer jig so that the groove faces downward, the side jigs are disposed on the left and right of the side spacer jig so that the groove faces outward, and the bobbin spacer jigs are attached to the front and rear of the side spacer jig so that the upper bobbin and the lower bobbin are spaced a predetermined distance apart, thereby forming a bobbin-jig assembly; a coated wire is hooked onto any one of the upper bobbin, the lower bobbin, and the side jig, and the bobbin / jig assembly is rotated around the left-right and top-bottom centers of the side spacer jig as a rotation center, thereby winding the coated wire around the grooves of the upper bobbin, the lower bobbin, and the side jig to form a coil; After the coil is formed, the rotation of the bobbin / jig assembly is stopped, and one of the bobbin spacer jigs and the side spacer jigs is removed, and then the side jig is removed while leaving the other bobbin spacer jig in place, thereby obtaining the coil assembly. A method for manufacturing a coil assembly.

6. an insulating sheet having electrical insulation properties is wound around the straight portion of the coil assembly manufactured by the manufacturing method according to claim 5, and then the other bobbin spacer jig is removed; A core made of a grain-oriented electromagnetic steel sheet is spirally wound on the insulating sheet. Transformer manufacturing method.

7. The transformer is a current transformer, After winding the insulating sheet and before winding the core, a conductor is wound on the insulating sheet, and a second insulating sheet is further wound on the conductor. The method for manufacturing the transformer according to claim 6 .

8. an insulating sheet having electrical insulation properties is wound around the straight portion of the coil assembly manufactured by the manufacturing method according to claim 5, and then the other bobbin spacer jig, the upper bobbin, and the lower bobbin are removed; A core made of a grain-oriented electromagnetic steel sheet is spirally wound on the insulating sheet. Transformer manufacturing method.

9. The transformer is a current transformer, After winding the insulating sheet and before winding the core, a conductor is wound on the insulating sheet, and a second insulating sheet is further wound on the conductor. The method for manufacturing a transformer according to claim 8 .

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