Transformer and transformer manufacturing method

Abstract

The invention provides a transformer and a manufacturing method of the transformer, which can be miniaturized or can improve the characteristics and reduce the manufacturing cost if the transformer is of the same size. This transformer (10) is provided with: a coil (20) in which a copper wire (21) is wound in a ring shape so as to have opposed linear sections (22); an insulating sheet (30) that has electrical insulating properties and is wound around the linear portion of the coil; and an iron core (40) formed from a grain-oriented magnetic steel sheet (41) and wound from the insulating sheet. The insulating sheet has a hook piece (31) formed at a winding end (33) located on the outer peripheral side or at a portion located on the outer peripheral side when wound around the linear portion, and the core has an open window (42) provided at a winding start end (43) located on the inner peripheral side of the grain-oriented electromagnetic steel sheet, and the hook piece engages with the open window.

Description

Technical Field

[0001] This invention relates to a transformer formed by rolling a directional electromagnet steel plate around a coil in a roller shape with an insulating material between the coil and the transformer, and a method for manufacturing the transformer. Background Technology

[0002] As a transformer for changing voltage and current, there are known transformers in which a core made of directional electromagnetic steel sheet is wound in a cylindrical shape on a coil wound into a rounded elliptical shape (for example, see Patent Document 1).

[0003] The coil and the iron core need to be electrically insulated. Therefore, as an insulating material, the coil is wound around an electrically insulating resin coil frame, and the iron core is wound around the outer periphery of the resin coil frame.

[0004] To wind the iron core onto the resin coil frame, the starting end of the winding of the iron core needs to engage with the resin coil frame. Therefore, a claw is formed at the starting end of the winding of the iron core, which bends the directional electromagnet plate inward at a right angle, and a recess is provided in the resin coil frame for the claw to be inserted. Furthermore, when the iron core is wound onto the resin coil frame, the claw hooks onto the recess.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 8-51034 Summary of the Invention

[0008] The problem that the invention aims to solve

[0009] Resin coil frames are molded resin products; therefore, to achieve strength, insulation, and heat resistance, a thickness of 0.8mm to 1.5mm is required. That is, the radial thickness of the resin coil frame is 1.6mm to 3.0mm. The increased thickness of the resin coil frame is directly related to the increasing size of transformers. Given a fixed transformer size, the diameter of the copper wire used in the coil must be reduced by a corresponding amount to the thickness of the resin coil frame, leading to increased losses due to temperature rise and increased voltage fluctuation characteristics.

[0010] Furthermore, the manufacture of resin coil frames incurs significant costs, including for equipment such as molds. Additionally, resin coil frames cannot flexibly accommodate changes in size or shape.

[0011] It should be noted that the iron core is formed by bending the front end of the directional electromagnetic steel plate to form a claw. However, the bending process of the claw needs to be carried out as another process after the iron core is cut or the front end of the iron core is cut into a pointed trapezoidal shape. Therefore, the number of processes in the iron core manufacturing process increases.

[0012] The purpose of this invention is to provide a transformer and a method for manufacturing the transformer that can be miniaturized or, if the size is the same, has improved characteristics and reduced manufacturing costs.

[0013] Methods for solving problems

[0014] The transformer of the present invention comprises:

[0015] A coil is formed by winding copper wire into a loop in a manner that has opposing straight sections;

[0016] An insulating sheet, having electrical insulation properties, is wound around the straight portion of the coil; and

[0017] A cylindrical iron core, which is made of directional electromagnetic steel plate and wound on the insulating sheet.

[0018] The insulating sheet has hook-like tabs formed on the outer peripheral side of the winding end or on the outer peripheral side when it is wound around the straight portion.

[0019] The iron core has an opening window at the winding start end located on the inner circumference side of the directional electromagnetic steel plate.

[0020] The hook plate engages with the opening window.

[0021] Alternatively, the hook-and-loop tab may be formed in a convex shape in the direction of protruding from the winding end of the insulating sheet.

[0022] It is permissible that the winding direction of the insulating sheet is opposite to that of the iron core.

[0023] It is possible that the hook is formed on the outer peripheral side of the portion when the insulating sheet is wound around the straight section, and is a convex cut toward the winding end or the winding beginning.

[0024] Possibly, the hook-and-loop tab has a convex cut facing the winding end of the insulating sheet.

[0025] The winding direction of the insulating sheet is opposite to that of the iron core.

[0026] Possibly, the hook-and-loop tab has a convex cut facing the beginning of the winding of the insulating sheet.

[0027] The insulating sheet and the iron core are wound in the same direction.

[0028] Furthermore, in the method for manufacturing the transformer of the present invention, wherein...

[0029] The method for manufacturing the transformer includes:

[0030] The coil making process involves winding copper wire into a loop using opposing straight sections to create the coil.

[0031] The insulating sheet manufacturing process involves creating a hook-and-loop piece on the outer periphery of the portion of the strip-shaped insulating sheet that has electrical insulation properties at the winding end or when it is wound around the straight section.

[0032] The temporary core manufacturing process involves punching an opening at the winding start end of a strip of directional electromagnetic steel sheet through stamping, winding the directional electromagnetic steel sheet into a cylindrical shape with the winding start end located on the inner circumference side, and then performing annealing heat treatment to obtain a temporary core.

[0033] The insulating sheet winding step involves winding and fixing the insulating sheet to the straight portion of the coil with the hook piece located on the outer periphery;

[0034] The temporary core configuration step involves embedding a rotatable roller into the winding center of the temporary core and arranging the temporary core side-by-side near the straight portion where the insulating sheet is wound.

[0035] In the first feeding step, the roller is rotated to feed out the winding end of the directional electromagnetic steel plate, forming a large ring surrounding the temporary core and the insulating sheet;

[0036] The temporary fixing step at the winding end involves temporarily fixing the winding end of the directional electromagnetic steel plate to the circumferential surface of the large ring.

[0037] The second feeding step involves rotating the roller while simultaneously rotating the temporary core and feeding out the directional electromagnetic steel plate until the winding start of the directional electromagnetic steel plate is contained within the large loop.

[0038] The hooking step involves hooking the opening window of the directional electromagnetic steel plate onto the hook plate of the insulating sheet;

[0039] The extraction step involves extracting the roller from the large ring.

[0040] In the winding step, through the extraction step, the directional electromagnetic steel plate shrinks in diameter due to the restoring force and winds around the insulating sheet wound on the straight section to obtain the iron core; and

[0041] The winding end fixing step involves fixing the winding end of the directional electromagnetic steel plate to the circumferential surface of the iron core.

[0042] Alternatively, the hook plate may be formed in a convex shape in a direction opposite to the winding direction of the iron core.

[0043] It is possible that, in the temporary core manufacturing step, while punching the opening window at the starting end of the winding of the directional electromagnetic steel plate through stamping, the starting end of the winding is cut into a sharp trapezoidal shape.

[0044] Invention Effects

[0045] According to the transformer and its manufacturing method of the present invention, since insulating sheets are used instead of resin coil frames, the insulation parts can be made thinner and lighter, and the diameter of the iron core can be reduced to achieve a lighter weight. Conversely, for transformers of the same size, the diameter of the copper wire used in the coils can be increased, which can suppress losses caused by temperature rise and reduce voltage fluctuation characteristics.

[0046] Insulating sheets can be obtained by purchasing existing products and cutting them to the desired size, thus offering greater flexibility in responding to design changes compared to resin coil frames. Furthermore, the elimination of molds and other equipment required for resin coil frames significantly reduces manufacturing costs.

[0047] For example, when the front end of the iron core is punched into a trapezoidal shape through stamping, an opening window in the iron core can be formed at the same time, which can suppress the increase in the number of processes. Attached Figure Description

[0048] Figure 1 These are (a) front view, (b) bottom view, and (c) rear view of a transformer according to an embodiment of the present invention.

[0049] Figure 2 It is along Figure 1 A sectional view of line A-A.

[0050] Figure 3 These are the coil's (a) front view, (b) bottom view, and (c) rear view.

[0051] Figure 4 The following are (a) front view, (b) bottom view, and (c) rear view of a coil with an insulating sheet wound around its straight section.

[0052] Figure 5 It is a three-dimensional view of the straight section of a coil wound with insulating sheets.

[0053] Figure 6 It is along Figure 4 The sectional view of line B-B in (c).

[0054] Figure 7 This is a top view of the insulating sheet.

[0055] Figure 8 This is a top view showing the process of making insulating sheets from long strips of insulating material.

[0056] Figure 9 This is a side view of a temporary core made by winding directional electromagnetic steel sheets.

[0057] Figure 10 This is a top view of the directional electromagnetic steel sheet before winding.

[0058] Figure 11 This is a top view showing the process of making directional electromagnetic steel sheets from long strips of directional electromagnetic steel sheet.

[0059] Figure 12 This is an explanatory diagram showing the process of winding a temporary core into the straight section of a coil with an insulating sheet.

[0060] Figure 13 This is a side view of the roller unit.

[0061] Figure 14 This diagram illustrates the steps of hooking the opening window of the iron core onto the hook plate of the insulating sheet.

[0062] Figure 15 This is a top view showing different implementations of the hooks on the insulating sheet.

[0063] Figure 16 This indicates that the opening window of the iron core is hooked onto... Figure 15 The diagram shows the steps for attaching the hook to the insulating sheet in (a).

[0064] Figure 17 This indicates that the opening window of the iron core is hooked onto... Figure 15 The diagram shows the steps for attaching the hook to the insulating sheet in (b).

[0065] Figure 18 This is a cross-sectional view of the core portion of a transformer, which is a comparative example of (a) the invention example and (b) the example of a coil frame made of resin as the insulating material.

[0066] Figure 19 It is a graph representing the offset voltage of an AC waveform.

[0067] Figure 20 These are (a) front view and (b) bottom view showing the configuration of the microphone used for noise measurement.

[0068] Figure 21 It is a cross-sectional view of the transformer, including the core, in which the insulating sheets are wound into a near-circular shape.

[0069] Figure 22 It is a cross-sectional view of the core portion of a transformer in which the coil is wound into a roughly circular cross-section. Detailed Implementation

[0070] Hereinafter, a transformer 10 according to an embodiment of the present invention will be described with reference to the accompanying drawings.

[0071] <Overall Overview of Transformer 10>

[0072] Figure 1 The images show (a) a front view, (b) a bottom view, and (c) a rear view of a transformer 10 according to an embodiment of the present invention. Additionally, Figure 2 It is along Figure 1 A cross-sectional view along line A-A. The transformer 10 of the present invention is configured such that a cylindrical iron core 40 is provided around the outer periphery of a coil 20 wound in a ring shape, with an insulating sheet 30 between the coil and the core 40, which is formed by winding a directional electromagnetic steel plate 41.

[0073] <Coil 20>

[0074] The coil 20 constituting the transformer 10 can be, for example, a single coil shared by the primary and secondary coils, wound with copper wire 21 such as enameled copper wire with an insulating coating (manufacturing steps of coil 20). When the primary and secondary coils are different coils, insulation is provided between the primary and secondary coils during winding. Figure 3 As shown, the coil 20 can be wound into a generally rounded quadrilateral with opposing straight sections 22, 22. The straight sections 22, 22 form the parts where the insulating sheet 30 and the iron core 40 are wound. The coil 20 shown in the figure is a structure in which the straight sections 22, 22 are connected to each other by an arc-shaped curved section 23, but the arc shape and curvature of the curved section 23 are not limited to this, and the curved section 23 may also include straight sections.

[0075] For example, such as Figure 2 As shown, coil 20 can be wound with a cross-section that is approximately hexagonal. It should be noted that, in addition to being approximately hexagonal, the cross-section of coil 20 can also be approximately octagonal, or other approximate polygons, or approximately circular (see reference). Figure 21 and Figure 22 ( ), roughly oval, etc.

[0076] like Figure 3 As shown, the coil 20 is fixed to one or more parts of the wound copper wire 21 by a fixing mechanism such as tape 25 to prevent the copper wire 21 from unraveling and to maintain its shape.

[0077] <Insulating sheet 30>

[0078] like Figures 4 to 6 As shown, the coil 20 has an insulating sheet 30 wound around its straight sections 22, 22. The insulating sheet 30 is made of, for example, Figure 7 The sheet body is made of an electrically insulating material. For example, insulating sheet 30 can be exemplified as an aromatic polyamide paper (made by DuPont: Nomex (registered trademark)) woven from aromatic polyamide fibers made of aromatic polyamide resin, or a polyester film.

[0079] The insulating sheet 30 is preferably made of 0.1 mm to 0.5 mm thickness, and more preferably of 0.2 mm to 0.4 mm thickness.

[0080] The insulating sheet 30 is formed to be able to be wound around the straight portion 22 and is at least wider than the directional electromagnet plate 41 constituting the core 40. To ensure the surface distance between the coil 20 and the core 40, it is preferable that the width of the insulating sheet 30 is at least 5 mm longer than the width of the directional electromagnet plate 41 (2.5 mm on one side). Furthermore, to achieve insulation, the length of the insulating sheet 30 needs to be set to be at least one turn around the outer periphery of the straight portion 22, that is, a length greater than or equal to the outer periphery length of the straight portion 22. Figure 6 In this embodiment, the insulating sheet 30 is the length of one circumference plus one side of the generally hexagonal coil 20. The insulating sheet 30 is preferably 1.2 to 2 circumferences long when the coil 20 is wound. It should be noted that, as... Figure 6 As shown, the winding method of the insulating sheet 30 is not limited to a generally hexagonal shape that is tightly wound around the periphery of the generally hexagonal coil 20, as described later. Figure 21 As shown, it can also be wound in a near-circular shape around the circumference of the approximately hexagonal coil 20.

[0081] like Figures 4 to 7 As shown, a hook-and-loop piece 31 is formed near the outer periphery of the insulating sheet 30 during winding, near the winding end 33, which engages with the iron core 40. The hook-and-loop piece 31 is a component formed by shaping a portion of the insulating sheet 30 into a convex shape. Figure 7 As shown, the hook piece 31 can be configured as a convex shape protruding in the direction of the winding end 33 of the insulating sheet 30, or, as described later. Figure 15 As shown, the insulating sheet 30 can be configured to have cutouts 34a and 34b.

[0082] The hook plate 31 can be set to a roughly rectangular shape when viewed from above, or a roughly trapezoidal shape with a pointed front end (see reference). Figure 5 , Figure 7 The hook plate 31 is roughly arc-shaped or roughly triangular. By forming a pointed shape at the front end, it can easily engage with the opening window 42 of the directional electromagnetic steel plate 41, and also has strength.

[0083] The hook plate 31 is preferably converging to a size of 5mm to 30mm in width and 5mm to 20mm in length, more preferably 10mm to 20mm in width and 7mm to 15mm in length, so as to have the required strength when engaged with the opening window 42 of the directional electromagnetic steel plate 41.

[0084] The insulating sheet 30 of the hook-and-hanger piece 31 having the above structure can pass through Figure 8The long strip of insulating sheet 30a shown is cut to form the insulating sheet 30 (manufacturing steps). For example, the insulating sheet 30a is pulled out from the component wound into a roller shape and formed using a Thomson die. Figure 8 The area indicated by reference numeral C in the attached drawing is cut off, thereby enabling the fabrication of the insulating sheet 30. Thus, in one process, a hook piece 31 can be formed at the center in the width direction, and the insulating sheet 30 can be cut to a predetermined length. It should be noted that, as... Figure 7 , Figure 8 As shown, at the beginning 32 of the winding of the insulating sheet 30, there are remaining cut marks 35 of the hook piece 31 of the next insulating sheet 30.

[0085] <Winding steps of insulating sheet 30>

[0086] like Figures 4 to 6 As shown, the manufactured insulating sheet 30 is wound around the straight portion 22 of the coil 20. The insulating sheet 30 is simply wound around the coil 20 with the hook piece 31 positioned on the outer periphery, and secured by a fixing mechanism such as tape 37 to prevent it from unraveling. The tape 37 is applied in a manner that avoids the hook piece 31. Thus, as... Figure 6 As shown, the hook-and-loop tab 31 extends outwards due to the rigidity of the insulating sheet 30. It should be noted that, to allow the hook-and-loop tab 31 to extend further outwards, the tape 37 is preferably as follows: Figure 4 , Figure 5 The adhesive tape 37 is attached to both outer sides of the hook piece 31 in a manner that suppresses its movement. By attaching the adhesive tape 37 to both outer sides of the hook piece 31, the hook piece 31 can be made rigid. When the hook piece 31 is inserted into the opening window 42 of the directional electromagnetic steel plate 41, which will be described next, even if the hook piece 31 is pulled by the iron core 40, the insulating sheet 30 can be prevented from loosening and the hook piece 31 from following.

[0087] <Temporary core 45>

[0088] An iron core 40 is formed on the insulating sheet 30 wound around the straight portion 22. For example... Figure 1 As shown, the iron core 40 is formed by winding a directional electromagnetic steel plate 41 around the insulating sheet 30.

[0089] The iron core 40 is made of directional electromagnetic steel plate 41, such as... Figure 9 It is formed by winding the temporary core 45, after annealing and heat treatment, into a cylindrical shape as shown, and then rewinding it around the insulating sheet 30. Figure 10 As shown, the directional electromagnetic steel plate 41 itself has an opening window 42 through its inner winding start end 43 during winding. This opening window 42 is a hole that can engage with the hook piece 31 of the insulating sheet 30. The opening window 42 has a width at least sufficient for the hook piece 31 to be inserted, and is preferably formed to be 1 mm to 5 mm larger than the width of the hook piece 31.

[0090] like Figure 10 As shown, the directional electromagnetic steel plate 41 is preferably formed as tapered portions 43a and 44a, which are tapered at the beginning of winding 43 and the end of winding 44 into a roughly trapezoidal shape with a pointed front end. This provides strength and prevents deformation during winding.

[0091] like Figure 11 As shown, the directional electromagnetic steel sheet 41 can be formed by cutting long strips of directional electromagnetic steel sheet 40a. To reduce the number of steps, it is preferable to... Figure 11 The area indicated by reference numeral D in the attached drawing is stamped, and the tapered portion 44a of the preceding directional electromagnetic steel plate 41, the tapered portion 43a of the following directional electromagnetic steel plate 41a, and the opening window 42 are formed by stamping in one stamping process.

[0092] It should be noted that while there is a concern about a reduction in properties due to the formation of an opening window 42 in the directional electromagnetic steel plate 41, since the punching only involves a portion of the front end of the directional electromagnetic steel plate 41, it has no impact on the properties.

[0093] Then, the directional electromagnetic steel plate 41, which is cut to form an opening window 42, is as follows: Figure 9 As shown, the coil is wound with the starting end 43 (forming the opening window 42) as the inner circumference and the ending end 44 as the outer circumference, and then heat-treated by annealing to produce a temporary core 45 (the steps for producing the temporary core 45). The inner diameter of the temporary core 45, i.e., the diameter of the winding center 45a, is the same as the outer diameter or maximum outer diameter of the insulating sheet 30 wound on the straight portion 22 of the coil 20. It should be noted that in a later process, after the temporary core 45 is wound around the outer circumference of the insulating sheet 30, it is tightened in the winding direction to eliminate any looseness in the core 40. At this time, in order to ensure that the core 40 can be tightened to the same outer diameter as the temporary core 45, after heat treatment, as shown... Figure 9 As shown by reference numeral 46 in the attached drawing, in order to effectively utilize the fastening standard in subsequent processes, it is preferable to appropriately mark a straight line along the radial direction on the temporary core 45 using a method capable of withstanding the annealing heat treatment. Furthermore, to prevent the core 40 from loosening or unraveling during the annealing heat treatment, it is preferable to, after winding the directional electromagnetic steel sheet 41, use a material resistant to heat treatment temperatures, such as iron-based or brass-based metal wire, to wind around the outer periphery of the temporary core 45, or to clamp it using a plate or clamp with a fixing function, in order to fix it in a way that prevents it from loosening and maintains its shape.

[0094] <Wrapping of Temporary Core 45: Manufacturing of Transformer 10>

[0095] The temporary core 45 is wound around the outer periphery of the insulating sheet 30 wound on the straight portion 22 of the coil 20 to form the iron core 40. The winding of the temporary core 45 can be performed using the following winding device 50.

[0096] like Figure 12 As shown in (a), the winding device 50 can be composed of a coil fixing mechanism 51 that holds the coil 20 and a roller unit 53 that holds and pulls out the temporary core 45. It should be noted that, for ease of understanding, in... Figure 12 In the middle, the directional electromagnetic steel plate 41 is shown in cross-section so that the opening window 42 can be seen.

[0097] The coil holding mechanism 51 can be exemplified, for example, as a clamp or clip, to hold the coil 20 in a manner that is substantially perpendicular to the straight portion 22 of the coil. The coil 20 is preferably held unwound from the insulating sheet 30. Figure 1 , Figure 3 The portion other than the straight section 22, for example, the curved section 23.

[0098] The temporary core 45 is disposed in the roll unit 53 consisting of the inner roll 54 and the outer roll 55. Figure 13 This is a side view of roller unit 53. The inner roller 54 and outer roller 55 are generally cylindrical or generally cylindrical bodies with anti-slip mechanisms 54a and 55a, such as rubber material (e.g., NBR: nitrile rubber) or polyurethane resin material, mounted or treated on their outer periphery. In the illustration, although the inner roller 54 is shown to have a smaller diameter compared to the outer roller 55, a structure in which they have the same diameter or the inner roller has a larger diameter could also be used. The inner roller 54 and outer roller 55 are forced towards each other. Furthermore, one of the inner roller 54 and outer roller 55 can be driven by a drive mechanism (not shown) such as a motor in the feeding direction of the temporary core 45, i.e. Figure 12 The rotational drive is in the direction of arrow R in (a). It should be noted that either the inner roller 54 or the outer roller 55 can be driven to rotate by the delivery of the temporary core 45. In this embodiment, in order to extract the inner roller 54 from the large ring 48 of the directional electromagnetic steel plate 41 in the following extraction step, the inner roller 54 is configured to be able to move up and down.

[0099] For coil 20 and temporary core 45, firstly as Figure 12 As shown in (a), the coil fixing mechanism 51 is provided on the straight section 22 of the coil 20, on which the insulating sheet 30 is wound. Additionally, the temporary core 45 inserts the winding center 45a into the inner roller 54, and is held by the inner roller 54 and the outer roller 55, arranged side-by-side with the straight section 22 of the coil 20 (the arrangement step of the core 40). For the coil 20, the straight section 22 on which the core 40 is subsequently wound is positioned on the side of the coil 20. Figure 12 As shown in (a), the temporary core 45 is configured such that the winding direction of the insulating sheet 30 is opposite to the winding direction of the temporary core 45. That is, when the insulating sheet 30 is wound clockwise, the temporary core 45 is configured such that the winding direction of the directional electromagnetic steel plate 41 (from the inner circumference to the outer circumference) is counterclockwise.

[0100] Starting from this state, move the inner roller 54 or the outer roller 55 towards... Figure 12 Rotating in the direction of arrow R (b), the temporary core 45 is rotated in the direction of arrow E while the winding end 33 of the temporary core 45 is pulled outward, passing between the straight sections 22 and 22, and then pulled back along the outer circumference of the temporary core 45. Thus, the delivered directional electromagnetic steel plate 41 forms a large ring 48 surrounding the temporary core 45 and the insulating sheet 30 (first delivery step). At this time, starting from the state of the temporary core 45, the diameter is expanded to form a large ring 48 while maintaining a roughly circular shape. This reduces the stress caused by mechanical strain after annealing heat treatment and suppresses the deterioration of magnetic characteristics, primarily the iron loss of the transformer.

[0101] like Figure 12 As shown in (b), the winding end 44 pulled out from the temporary core 45 passes between the inner roller 54 and the outer roller 55, and the passing winding end 44 is temporarily fixed to the circumference of the core 45 by a fixing mechanism such as tape 47 (the temporary fixing step of the winding end 44 of the temporary core 45).

[0102] like Figure 12 As shown in (c), from this state the inner roller 54 or the outer roller 55 is further rotated to feed the directional electromagnetic steel plate 41 out from the temporary core 45 (second feeding step).

[0103] Then, as Figure 12 As shown in (d), the inner roller 54 or the outer roller 55 is rotated until all the directional electromagnetic steel plates 41 of the temporary cores 45 are contained within the large ring 48.

[0104] Next, the opening 42 formed at the winding start 43 of the directional electromagnetic steel plate 41 of the large ring 48 is hooked onto the hook piece 31 of the insulating sheet 30. Specifically, in Figure 12 In (d), the winding start end 43 is located on the side of rollers 54 and 55, but from this state onwards... Figure 12 As shown in (e), the large ring 48 is rotated. The directional electromagnetic steel plate 41 has a restoring force to return to the shape of the temporary core 45, which has a diameter smaller than that of the large ring 48, thus causing the winding beginning 43 to curl inward, as shown in (e). Figure 12 (e) and magnification Figure 14 As shown in (a), it abuts against the insulating sheet 30. Hook tabs 31 are formed on the insulating sheet 30, so by further rotating the large loop 48 in this state, it winds around the starting end 43 towards... Figure 14 The arrow in (a) moves in the direction of F, as shown. Figure 12 (e) and Figure 14 As shown in (b), the hook piece 31 is embedded in the opening window 42 (hooking step).

[0105] With the hook plate 31 embedded in the opening window 42, when peeling off the tape 47 and pulling out the inner roller 54 (for example, moving the inner roller 54 downwards), as... Figure 12 As shown in (f), even after annealing heat treatment, the directional electromagnetic steel plate 41 shrinks in diameter due to the restoring force of residual stress and is wound onto the insulating sheet 30 (winding step). The wound directional electromagnetic steel plate 41 is tightened until it becomes... Figure 9 The temporary core 45 shown has the same outer diameter. At this time, if... Figure 9 If the straight line 46 marked on the temporary winding core 45 is not aligned, it can be corrected by manually winding the core and tightening it using appropriate methods until the line 46 is properly aligned. It should be noted that if the tightening is excessive at this point and the straight line is not aligned, new stress will be generated, leading to mechanical strain and deterioration of the magnetic properties, which should be avoided.

[0106] Then, in a tightened state, such as Figure 1 As shown in (a) and (c), the winding end 44 of the directional electromagnetic steel plate 41 is fixed to the circumferential surface of the iron core 40 by spot welding 49, etc. (winding end fixing step). Afterwards, the coil fixing mechanism 51 is operated to release the holding of the coil 20.

[0107] Next, a temporary core 45 is wound around the insulating sheet 30 wound around the other straight portion 22 in the same manner, and the winding end 44 is fixed, thereby enabling the manufacture of Figure 1 The transformer 10 shown. Subsequently, regardless of its shape or form, transformers are usually finished by impregnation with resin varnish for moisture protection, and the transformer in this invention is no exception.

[0108] According to the manufacturing method described above, the directional electromagnetic steel plate 41, starting from the state of the temporary core 45, expands in diameter to a large ring 48 while maintaining a roughly circular shape, and is wound around the straight section 22 while maintaining a roughly circular shape to form the iron core 40. Therefore, for the directional electromagnetic steel plate 41, the stress caused by mechanical strain after annealing heat treatment is less, thus suppressing the deterioration of magnetic characteristics, mainly the iron loss of the transformer.

[0109] In the transformer 10 of the present invention, instead of a resin coil frame, an insulating sheet 30 is used as the insulating material between the coil 20 and the core 40. The insulating sheet 30 is thinner than the resin coil frame, thus enabling a thinner and lighter insulating portion and miniaturization of the transformer 10. Furthermore, when the transformer 10 is manufactured with the same dimensions as a transformer using a resin coil frame, the diameter of the copper wire used in the coil can be increased, suppressing losses caused by temperature rise and stably optimizing voltage fluctuation characteristics.

[0110] The insulating sheet 30 can be purchased as an existing product and easily cut to the desired size, thus allowing for greater flexibility in responding to design changes compared to resin coil frames. Furthermore, since it eliminates the need for injection molding molds and molding equipment required for manufacturing resin coil frames, manufacturing costs can be significantly reduced.

[0111] For the engaging opening 42 formed on the directional electromagnetic steel plate 41, for example, when the front end of the directional electromagnetic steel plate 41 is cut off, it can be punched into a roughly trapezoidal shape using a common stamping method and processed at the same time, so no new process is added.

[0112] <Different Implementations of Hook and Hanger Plate 31>

[0113] Figure 15 These are different embodiments of the hook pieces 31a and 31b of the insulating sheet 30. In the above embodiments, such as Figure 7 As shown, a hook-and-loop tab 31 with a convex shape is formed from the end edge of the winding end 33 of the insulating sheet 30. Figure 15 In this process, hook pieces 31a and 31b are formed by making cuts 34a and 34b at the outer peripheral portion of the coil 20 when the insulating sheet 30 is wound around the straight portion 22 of the coil 20, i.e., at the position of the circumference from the winding end 33 to the straight portion 22.

[0114] Figure 15 (a) indicates an insulating sheet 30 with a cutout 34a protruding toward the winding end 33, forming a hook-and-loop tab 31a. Additionally, Figure 15 (b) shows the hook plate 31b formed towards the... Figure 15 (a) The opposite direction, i.e., the insulating sheet 30 is wound around the protruding cut 34b on the side of the starting end 32. Any hook pieces 31a and 31b are roughly triangular in shape with sharp front ends, but they can also be roughly trapezoidal, roughly rectangular, roughly arc-shaped, etc.

[0115] Figure 15 The protruding direction of the hook piece 31a of the insulating sheet 30 shown in (a) is the same as that of the hook piece 31a. Figures 4 to 7 The protruding direction of the hook piece 31 of the insulating sheet 30 is the same. Therefore, the temporary core 45 is configured such that the winding direction of the directional electromagnetic steel plate 41 from the inner periphery to the outer periphery is opposite to the winding direction of the insulating sheet 30, which enables it to achieve the same winding direction as described above. Figure 14 The same technique is used to engage the hook plate 31a with the opening window 42. Specifically, as... Figure 12 As shown in (e), with the winding start 32 of the directional electromagnetic steel plate 41 in contact with the circumferential surface of the insulating sheet 30, the large ring 48 is slightly rotated, as shown in (e). Figure 16 As shown in (a) and (b), the opening window 42 is engaged with the protruding hook piece 31a. The subsequent steps are the same as in the above embodiment.

[0116] Figure 15 The protruding direction of the hook piece 31b in (b) is opposite to that in the above embodiment. Therefore, in order to engage the opening window 42 with the hook piece 31b, the winding direction of the insulating sheet 30 and the winding direction of the temporary core 45 are configured to be the same. (Refer to...) Figure 17 From (a), it can be seen that the insulating sheet 30 becomes with Figure 16 (a) The opposite direction of the winding. Then, as described above. Figure 12 As shown in (e), with the winding start 32 of the directional electromagnetic steel plate 41 in contact with the circumferential surface of the insulating sheet 30, the large ring 48 is slightly rotated, as shown in (e). Figure 17 As shown in (a) and (b), the opening window 42 is engaged with the protruding hook piece 31b. The subsequent steps are the same as in the above embodiment.

[0117] Example

[0118] Made Figure 18 The transformer 10 shown in (a) is an example of the invention that uses the insulating sheet 30 made by the present invention as the insulating material. Figure 18 (b) shows a comparative example transformer 70 using a resin coil frame 72 as insulation material. The manufactured transformers 10 and 70 are single-phase, single-turn transformers with a rated capacity of 2 kVA.

[0119] The coil 20 of the invention is formed by winding a 2.3mm diameter copper wire 21 with 100 turns, setting an output tap, and then winding it 200 turns. The insulating sheet 30 has... Figure 7 The hook plate 31 shown has a thickness of 0.25mm, as... Figure 18 As shown in (a), the insulating sheet 30 is wound 1 turn + 1 side. The iron core 40 is a temporary core 45 formed by winding a directional electromagnetic steel plate 41 with an inner diameter of Φ40 and a thickness of 0.23 mm 60 turns. Figure 12 , Figure 14 It is formed by winding the key points onto the insulating sheet 30.

[0120] On the other hand, in order to maintain the shape of the winding, a resin coil frame 72 with a diameter of 0.8 to 1.5 mm is used to wind the coil 71 on the inside with the same number of turns as in the invention example, but with a diameter of 2.1 mm smaller. Furthermore, an iron core identical to the iron core 40 of the invention example is wound around the outer periphery of the resin coil frame 72. Figure 18 As shown in (b), the resin coil frame 72 and the directional electromagnet plate 75 are engaged by a claw 76 formed by bending inward at the winding start end of the directional electromagnet plate 75 and a recess 73 into which the claw 76 formed on the circumferential surface of the resin coil frame 72 is inserted. It should be noted that, regarding the transformer 70 of the comparative example, in relation to... Figure 12When the temporary core is wound onto the resin coil frame 72 using the same method, since there are claws 76 on the directional electromagnet plate 75, it is necessary to... Figure 13 A recessed part is provided on the inner roller 54 in the center of the length direction of the inner roller 54 to avoid the claw piece 76.

[0121] The invention allows the use of thin, highly insulating sheets 30, such as aramid sheets or polyester resin molded sheets. Thus, when the transformers 10 and 70 of the invention and comparative examples have the same size cores 40 and 74, the coil 20 of the invention can be wound with the same wire diameter of 2.3 mm as the coil 71 of the comparative example (2.1 mm). Corresponding to the increased wire diameter, the DC resistance decreases, reducing copper losses (calculated as the square of the current multiplied by the resistance) by 15%. This reduction in copper losses reduces temperature rise and improves voltage fluctuation.

[0122] For example, in order to make the characteristics of the comparative example the same as those of the inventive example, when the transformer 70 is made with the same wire diameter of Φ2.3mm and 200 turns as in the inventive example, the coil 71 becomes larger. Therefore, compared with the inner diameter of Φ40mm in the present invention, a core 74 with an inner diameter of Φ44mm and 60 turns is required. The outer diameter of the core 74 is 72mm. Compared with the inventive example, Figure 18 The dimension d increases by 4mm. In addition, the amount of directional electromagnetic steel plate used in the core 74 increases, resulting in a weight increase of approximately 7.4%. If the transformer 70 of the comparative example is designed with the same wire diameter and number of turns as the invention example, the product of the comparative example becomes larger and heavier.

[0123] The above description is for illustrative purposes and should not be construed as limiting or restricting the scope of the invention as described in the technical solution. Furthermore, the structures of various parts of the invention are not limited to the above embodiments, and various modifications can be made within the technical scope described in the technical solution.

[0124] For example, the hook-and-hanger piece 31 can be formed from other sheet-like components and adhered to the insulating sheet 30, etc. Alternatively, the hook-and-hanger piece 31 can also be made of... Figure 7 , Figure 15 The hook plate 31 shown is folded back outwards.

[0125] In recent years, systems using energy storage devices such as batteries to convert solar power into commercial power for residential use have become increasingly common in solar power regulators. For example, in Japan, transformers are used to convert 200V AC to 100V. At this time, such as... Figure 19As shown, the following phenomenon was confirmed: an offset voltage of 0-0.3V is generated during the AC conversion from DC, resulting in magnetic flux imbalance and increased noise from the transformer. Regarding the transformer's input voltage, the commercial power supply voltage is constant, the maximum magnetic flux density remains unchanged, and the inherent magnetostrictive vibration intensity of the directional electromagnetic steel plate remains unchanged. However, the positive side of the voltage increases while the negative side decreases. Therefore, due to the imbalance in magnetic flux density, the directional electromagnetic steel plate is prone to mechanical vibration, and the noise caused by this mechanical vibration increases.

[0126] The transformer 10 of the present invention has no mating part on the iron core 40 as a magnetic circuit structure, thus reducing noise generation caused by magnetostrictive vibration of the directional electromagnetic steel plate 41. Furthermore, it has a structure in which the directional electromagnetic steel plate 41 is fastened by the hook structure of the insulating sheet 30. Therefore, the winding and stacking gap of the directional electromagnetic steel plate 41 can be minimized, thereby suppressing mechanical vibration of the directional electromagnetic steel plate 41 and reducing noise. The measurement results are shown in Table 1. Figure 20 This indicates the configuration of the microphone 80 used for measurement.

[0127] [Table 1]

[0128] Transformer of the Invention 35~38dB Comparative example transformer 40~50dB

[0129] It should be noted that when fastening the directional electromagnetic steel plate 41, it is better to fasten it to the state before it is installed in the coil 20. If it is over-tightened, mechanical strain will occur, and the loss caused by the deterioration of magnetic properties will increase.

[0130] <Winding method of insulating sheet 30>

[0131] In the above Figure 6 In this process, the insulating sheet 30 is formed into a generally hexagonal cylindrical shape by being tightly wound around a generally hexagonal coil 20. Figure 21 In this process, the insulating sheet 30 is wound around the circumference of the approximately hexagonal coil 20 in a manner where the cross-section is nearly circular, specifically a hexagon with arc-shaped edges.

[0132] <Different embodiments of the shape of coil 20>

[0133] Figure 22 This is a cross-sectional view of the core 40 of the transformer 10, in which the coil 20 is wound into a generally circular shape. In the illustration, the coil 20 is wound into a generally circular shape. This increases the occupancy of the coil 20 compared to a generally hexagonal shape. Additionally, the insulating sheet 30 is wound into the coil 20 in a generally circular shape.

[0134] As mentioned above Figure 21 and Figure 22In this way, by reducing the gap between the coil 20 and the insulating sheet 30 and the gap between the insulating sheet 30 and the iron core 40, the inner side of the iron core 40 can be suppressed, and noise caused by mechanical vibration can be suppressed.

[0135] Explanation of reference numerals in the attached figures:

[0136] 10 Transformers

[0137] 20 coils

[0138] 22. Straight Section

[0139] 30 Insulating sheet

[0140] 31 Hook and Hanging Plate

[0141] 40 iron core

[0142] 41 Directional Electromagnetic Steel Sheet

[0143] 42. Open window.

Claims

1. A transformer, wherein, The transformer has the following features: A coil is formed by winding copper wire into a loop in a manner that has opposing straight sections; An insulating sheet, having electrical insulation properties, is wound around the straight portion of the coil; and A cylindrical iron core, which is made of directional electromagnetic steel plate and wound on the insulating sheet.

2. The transformer according to claim 1, wherein, The insulating sheet has hook-like tabs formed on the outer peripheral side of the winding end or on the outer peripheral side when it is wound around the straight portion. The iron core has an opening window at the winding start end located on the inner circumference side of the directional electromagnetic steel plate. The hook plate engages with the opening window.

3. The transformer according to claim 2, wherein, The hook piece is formed in a convex shape that protrudes in the direction of the winding end of the insulating sheet.

4. The transformer according to claim 3, wherein, The winding direction of the insulating sheet is opposite to that of the iron core.

5. The transformer according to claim 4, wherein, The hook tab is formed on the outer peripheral side of the portion when the insulating sheet is wound around the straight section, and is a convex cut toward the winding end or the winding beginning.

6. The transformer according to claim 5, wherein, The hook tab is a convex cut facing the winding end side of the insulating sheet. The winding direction of the insulating sheet is opposite to that of the iron core.

7. The transformer according to claim 5, wherein, The hook tab has a convex cut facing the beginning of the winding of the insulating sheet. The insulating sheet and the iron core are wound in the same direction.

8. A method for manufacturing a transformer, wherein, The method for manufacturing the transformer includes: The coil making process involves winding copper wire into a loop using opposing straight sections to create the coil. The insulating sheet manufacturing process involves creating hook-and-loop tabs at the winding end of the electrically insulating strip or on the outer periphery of the portion wound around the straight section. The temporary core manufacturing process involves punching an opening at the winding start end of a strip of directional electromagnetic steel sheet using a stamping process, winding the directional electromagnetic steel sheet into a cylindrical shape with the winding start end located on the inner circumference side, and then performing an annealing heat treatment to obtain a temporary core. The insulating sheet winding step involves winding and fixing the insulating sheet to the straight portion of the coil with the hook piece located on the outer periphery; The temporary core configuration step involves embedding a rotatable roller into the winding center of the temporary core and arranging the temporary core side-by-side near the straight portion where the insulating sheet is wound. In the first feeding step, the roller is rotated to feed out the winding end of the directional electromagnetic steel plate, forming a large ring surrounding the temporary core and the insulating sheet; The temporary fixing step at the winding end involves temporarily fixing the winding end of the directional electromagnetic steel plate to the circumferential surface of the large ring. The second feeding step involves rotating the roller while simultaneously rotating the temporary core and feeding out the directional electromagnetic steel plate until the winding start of the directional electromagnetic steel plate is contained within the large loop. The hooking step involves hooking the opening window of the directional electromagnetic steel plate onto the hook plate of the insulating sheet; The extraction step involves extracting the roller from the large ring. In the winding step, through the extraction step, the directional electromagnetic steel plate shrinks in diameter due to the restoring force and is wound around the insulating sheet wound around the straight section to obtain the iron core; and The winding end fixing step involves fixing the winding end of the directional electromagnetic steel plate to the circumferential surface of the iron core.

9. The method for manufacturing a transformer according to claim 8, wherein, The hook plate is formed into a convex shape that protrudes in the opposite direction to the winding direction of the iron core.

10. The method for manufacturing a transformer according to claim 9, wherein, In the temporary core fabrication step, while punching the opening window at the starting end of the winding of the directional electromagnetic steel plate through stamping, the starting end of the winding is cut into a pointed trapezoidal shape.

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