Coil manufacturing method

Abstract

To provide a coil manufacturing method that can improve a space factor and heat dissipation, avoid deterioration of characteristics due to cutting and joining, and enable mass production.SOLUTION: A coil manufacturing method includes a step for preparing a spiral structure, a step for forming the spiral structure, and a step of covering the spiral structure with an insulating resin.SELECTED DRAWING: Figure 10

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a coil using a conductor.

Background Art

[0002] As a coil device in which a coil is disposed around a core (stator core) of a stator core, for example, electric devices such as motors, generators, and transformers can be mentioned. In such a coil device, it is important to improve the occupancy rate of the coil in the core in order to reduce losses and miniaturize.

[0003] As a coil capable of improving the occupancy rate in the core, a coil using a rectangular conductor (hereinafter referred to as a rectangular coil) has been conventionally known. A rectangular coil is also called a flat-wound (angular-wound) coil, a square (square-shaped) coil, an edgewise coil, etc., and is a coil wound with a rectangular conductor having a substantially circular cross-sectional shape orthogonal to the longitudinal direction with respect to a coil wound with a round wire having a substantially circular cross-sectional shape orthogonal to the longitudinal direction.

[0004] Further, as a method for manufacturing a rectangular coil, a method of winding a long rectangular conductor (square conductor) into a substantially rectangular shape is known (see, for example, Patent Document 1). Also, a method of laminating rectangular conductors (flat conductive materials) for one turn of the coil, overlapping the upper surface of the end of the lower stage and the lower surface of the start of the upper stage, and repeating with joining means to form a spiral structure is also known (see, for example, Patent Document 2).

[0005] Further, as a method for connecting conductors, a cold pressure welding method is known.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Summary of the Invention

[0007] However, in methods such as the one described in Patent Document 1, where a long length of flat rectangular wire is wound in a roughly rectangular shape, it is unavoidable that the corners (both on the outer and inner sides) will be curved, resulting in a rounded corner shape. Since the core is generally a prism shape with roughly right-angled corners, arranging a rounded-corner coil around it creates a space between the core and the coil. This space accumulates heat during the operation of the coil device, resulting in poor heat dissipation and an increase in coil resistance, which prevents the coil device from becoming highly efficient. Furthermore, there were limitations to improving the coil's space factor at the corners.

[0008] Furthermore, the flat rectangular conductors used in the coils have their outer circumference pre-coated with insulating resin. When these are wound, the coating thins out at the corners of the outer circumference due to curvature, which causes a decrease in the voltage resistance of the coil device.

[0009] On the other hand, in the case of a method of stacking and joining flat rectangular conductors for one turn of a coil, as described in Patent Document 2, it is possible to avoid curving the corners, thus avoiding the aforementioned problems with heat dissipation and space factor. However, even though the connection is made by joining means, it is unavoidable that the characteristics at the joint between the upper end surface of the lower layer and the lower start end surface of the upper layer will deteriorate compared to the uncut portion, leaving problems in terms of operational stability.

[0010] Furthermore, while cold pressure welding of round wire conductors is a known method for connecting conductors, it has been difficult to cold pressure weld flat rectangular wires together in a way that improves the stability of the connection.

[0011] Furthermore, in coil manufacturing equipment that produces coils by continuously pressing together multiple conductors, sufficient consideration was not given to improving mass productivity.

[0012] The present invention aims to provide a coil manufacturing method that enables improved space utilization and heat dissipation, avoids performance degradation due to cutting and joining, and allows for mass production. [Means for solving the problem]

[0013] The present invention comprises the steps of: preparing a helical structure in which each region of one full turn of the helix includes a bent portion; deforming the helical structure so as to compress it in the axial direction of the helix; and shaping the helical structure in the axial direction of the helix to match the shape of a stator. After the molding process The present invention relates to a coil manufacturing method characterized by comprising the step of covering each of the aforementioned circular regions with an insulating resin. [Effects of the Invention]

[0014] According to the present invention, it is possible to improve the packing factor and heat dissipation, avoid the degradation of characteristics due to cutting and joining, and provide a coil manufacturing method that enables mass production. [Brief explanation of the drawing]

[0015] [Figure 1] (a) This is a schematic external view (front view) showing the configuration of the cold pressure welding apparatus according to this embodiment. (b) This is a top view of a flat conductor. (c) This is a cross-sectional view taken along line AA in Figure 1(b). [Figure 2] This is a schematic external view (front view) of the holding portion of the cold welding apparatus according to this embodiment. [Figure 3] This is a schematic external view (front view) of the holding portion of the cold welding apparatus according to this embodiment. [Figure 4] This is a schematic side view showing the holding portion of the cold welding apparatus according to this embodiment. [Figure 5] This is a top view showing a rectangular conductor according to this embodiment. [Figure 6] This is a schematic diagram showing the cold pressure welding process of a rectangular conductor according to this embodiment. [Figure 7]It is a diagram showing a coil manufacturing apparatus according to this embodiment, (a) is a side view of a holding part, (b) is a front view of a coil, and (c) is a front view of the holding part. [Figure 8] It is a side view of a holding part of a coil manufacturing apparatus according to this embodiment. [Figure 9] It is a schematic diagram for explaining a coil manufacturing method according to this embodiment. [Figure 10] It is a schematic diagram for explaining a coil manufacturing method according to this embodiment. [Figure 11] It is a modified example of a coil piece according to this embodiment. [Figure 12] It is a diagram for explaining a modified example of a coil manufacturing apparatus and a coil manufacturing method according to this embodiment. [Figure 13] It is a diagram for explaining a coil according to this embodiment, (a) is a front view, (b) is a cross-sectional view, and (c) is a side view. [Figure 14] It is a diagram showing experimental results regarding the heat generation amounts of a coil according to this embodiment and a coil of a conventional example. [Figure 15] It is a diagram for explaining a method of attaching a coil according to this embodiment to a status score, (a) is a side view, (b) is a cross-sectional view of FIG. (a), and (c) is a cross-sectional view of FIG. (a). [Figure 16] It is a side view showing the spiral structure of a coil according to this embodiment. [Figure 17] It is a diagram showing the spiral structure of a coil according to this embodiment, (a) is an external perspective view, (b) is a side view, (c) is an external perspective view, and (d) is a side view.

Embodiments for Carrying Out the Invention

[0016] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0017] <Cold Pressure Welding Device> Figure 1 is a diagram illustrating the cold welding apparatus 10 according to this embodiment. Figure 1(a) is a schematic external view (front view) showing part of the configuration of the cold welding apparatus 10. Figure 1(b) is a top view of the flat conductor C. Figure 1(c) is a cross-sectional view taken along line AA in Figure 1(b).

[0018] As shown in Figure (a), the cold welding apparatus 10 is a device for cold welding two flat conductors C (C1, C2), and has a first holding part 11 and a second holding part 12. In the following description, a flat conductor C refers to a strip-shaped (tape-shaped) conductor that is planar to a round wire conductor, as shown in Figures (b) and (c). That is, a flat conductor is a strip-shaped member that is long in a predetermined direction and has two opposing wide surfaces WS and two opposing narrow surfaces WT, as shown in Figures (b) and (c), and has a cross section perpendicular to the longitudinal direction BL of the strip (cross section along line AA in Figure (b)) that is rectangular or rounded rectangular as shown in Figure (c). In the following description, as an example of a flat conductor, a rectangular flat conductor (upper figure in Figures (b) and (c)) with a cross section perpendicular to the longitudinal direction of the strip will be described as an example. In this invention, the flat conductor C may be any strip-shaped conductor that is planar relative to a round wire conductor, and may have a cross-sectional view that is approximately square in the cross-section of line AA in Figure (b).

[0019] The first holding part 11 is movable along a first direction (the longitudinal direction of the rectangular conductor; the X direction in Figure 1(a)) and is composed of a first upper holding body 111 and a first lower holding body 112. The first upper holding body 111 and the first lower holding body 112 are arranged opposite each other so as to have opposing surfaces OS1 along the first direction (hereinafter referred to as the X direction). In this embodiment, for the sake of explanation, the upper holding body shown is referred to as the first upper holding body 111 and the lower holding body shown is referred to as the first lower holding body 112, but these upper and lower parts are not necessarily limited to the vertical direction. That is, Figure 1(a) may be a top view of the cold pressure welding apparatus 10, in which case the first upper holding body 111 may be, for example, the holding body on the far side, and the first lower holding body 112 may be, for example, the holding body on the near side. Furthermore, the first upper retainer 111 may be, for example, the left retainer, and the first lower retainer 112 may be, for example, the right retainer.

[0020] The first upper holder 111 and the first lower holder 112 are movable along the X direction, and their opposing surfaces OS1 along the X direction are movable so as to come into contact with or separate from each other along a second direction (the thickness direction of the rectangular conductor; the Y direction in Figure (a)). The Y direction is a different direction from the X direction, for example, a direction perpendicular to the X direction.

[0021] The second retaining part 12 is positioned opposite the first retaining part 11 such that it has a facing surface OS2 along a second direction (hereinafter referred to as the Y direction) and has the same configuration as the first retaining part 11.Therefore, a detailed explanation will be omitted, but the second retaining part 12 is movable along the X direction and is composed of a second upper retaining body 121 and a second lower retaining body 122.The description of "upper and lower" for the second upper retaining body 121 and the second lower retaining body 122 is the same as for the first retaining part 11.

[0022] The second upper holder 121 and the second lower holder 122 are movable along the X direction, and are also movable along the Y direction such that their opposing surfaces OS1 come into contact with or separate from each other.

[0023] Furthermore, the first retaining portion 11 and the second retaining portion 12 are biased by a biasing member (e.g., a coil spring) 15 in a direction that separates them from each other along the X direction. Although not shown in the figures, the first upper retaining body 111 and the first lower retaining body 112 are biased by a biasing member (e.g., a coil spring) in a direction that separates them from each other along the Y direction, and the second upper retaining body 121 and the second lower retaining body 122 are biased by a biasing member (e.g., a coil spring) in a direction that separates them from each other along the Y direction.

[0024] The first rectangular conductor C1 and the second rectangular conductor C2 are restricted from moving in the Y direction by a movement restricting mechanism (not shown). Furthermore, the first rectangular conductor C1 and the second rectangular conductor C2 can move toward each other along the X direction, but their movement toward each other is restricted.

[0025] Furthermore, a pressing portion 18 is provided on the outer side of the first holding portion 11 and the second holding portion 12 in the Y direction. The pressing portion 18 presses the first upper holding body 111 and the first lower holding body 112 so that they come into contact with each other, and also presses the second upper holding body 121 and the second lower holding body 122 so that they come into contact with each other.

[0026] Figures 2 and 3 are front views showing the first holding part 11 and the second holding part 12, illustrating their movement states.

[0027] Figure 2 is a diagram that mainly illustrates the movement of the first holding part 11 (first upper holding body 111 and first lower holding body 112) and the second holding part 12 (second upper holding body 121 and second lower holding body 122) mainly along the Y direction.

[0028] The state shown in Figure (a) is the position where the opposing surfaces OS1 of the first upper holder 111 and the first lower holder 112 (and similarly the second upper holder 121 and the second lower holder 122) are furthest apart in the Y direction. This position will hereafter be referred to as the Y-direction separation position. This state is also the position where the opposing surfaces OS2 of the first holding part 11 and the second holding part 12 are furthest apart in the X direction. This position will hereafter be referred to as the X-direction separation position.

[0029] Figure (b) shows the state after moving from the state shown in Figure (a) to a position where the opposing surfaces OS1 of the first upper holder 111 and the first lower holder 112 come into contact. In this state, the first holder 11 clamps the first rectangular conductor (wide surface WS) between the first upper holder 111 and the first lower holder 112, and the second holder 12 clamps the second rectangular conductor (wide surface WS) between the second upper holder 121 and the second lower holder 122.

[0030] The first holding portion 11 clamps the first rectangular conductor C1 so that it protrudes from the opposing surface OS2 along the Y direction toward the second holding portion 12. Similarly, the second holding portion 12 clamps the second rectangular conductor C2 so that it protrudes from the opposing surface OS2 along the Y direction toward the first holding portion 11. The amount A1 of the protrusion of the first rectangular conductor C1 from the first holding portion 11 and the amount A2 of the protrusion of the second rectangular conductor C2 from the second holding portion 12 will be described later.

[0031] In this manner, the position where the opposing surfaces OS1 of the first upper holder 111 and the first lower holder 112 (the second upper holder 121 and the second lower holder 122) come into contact is referred to as the clamping position in the following explanation. In other words, the first upper holder 111 and the first lower holder 112 (the second upper holder 121 and the second lower holder 122) are movable between the clamping position and the Y-direction separation position.

[0032] Furthermore, as shown in Figure (c), the position between the clamping position and the Y-direction separation position includes a position where the clamping is released (in the Y-direction). The Y-direction release position (hereinafter referred to as the Y-direction release position) is a position where the first upper holder 111 and the first lower holder 112 (the second upper holder 121 and the second lower holder 122) are separated by a smaller distance than the Y-direction separation position.

[0033] Furthermore, it is also possible to move from the Y-direction release position in Figure (c) to the position where the opposing surfaces OS1 of the first upper holder 111 and the first lower holder 112 (the second upper holder 121 and the second lower holder 122) come into contact, thereby transitioning to the state shown in Figure (b).

[0034] In Figure 2, the positions of the first holding part 11 and the second holding part 12 along the X direction are both maintained at positions separated in the X direction.

[0035] Figure 3 illustrates the movement of the first holding part 11 and the second holding part 12, mainly along the X direction. Figure 3(a) shows the position where the first retaining part 11 and the second retaining part 12 have moved along the X direction from the state in Figure 2(b) so that their opposing surfaces OS2 are closest together. Hereafter, this position will be referred to as the proximity position. In other words, the first retaining part 11 and the second retaining part 12 can move between the separated position in the X direction shown in Figure 2 and the proximity position shown in Figure 3(a). Even in the proximity position, the first retaining part 11 and the second retaining part 12 do not come into contact.

[0036] The first holding part 11 holds the first rectangular conductor C1 with a protrusion amount A, and the second holding part 12 holds the second rectangular conductor C2 with a protrusion amount A2 (Figure 2(b)). Therefore, when the first holding part 11 and the second holding part 12 are in close proximity, the first holding part 11 and the second holding part 12 do not come into contact, but the first rectangular conductor C1 and the second rectangular conductor C2 come into contact (join) and press against each other. In other words, the protrusion amount A1 of the first rectangular conductor C1 from the first holding part 11 and the protrusion amount A2 of the second rectangular conductor C2 from the second holding part 12 are each slightly longer than the length at which the first holding part 11 and the second holding part 12 come into contact with each other (an amount that allows them to press against each other after coming into contact).

[0037] Furthermore, as shown in Figure (b), the position between the proximity position and the position separated in the X direction (Figure 2(a)) includes a release position (in the X direction) of the pressure. The release position in the X direction (hereinafter referred to as the X-direction release position) is a position where the first holding part 11 and the second holding part 12 are separated by a smaller distance than the X-direction separation position. When the first holding part 11 and the second holding part 12 are in the X-direction release position, the first upper holding body 111 and the first lower holding body 112 also separate and move to the Y-direction release position, and the second upper holding body 121 and the second lower holding body 122 also separate and move to the Y-direction release position.

[0038] Furthermore, it is possible to transition from the release position in the X direction shown in Figure (b) to the state shown in Figure (a).

[0039] Figure 4 is a side view of the first retaining part 11 (viewed from the V-direction arrow in Figure 1) as seen from the second retaining part 12 side, looking at the opposing surface OS2 of the first retaining part 11. Figure 4(a) shows the state in which the first upper retaining body 111 and the first lower retaining body 112 are separated in the Y direction (the state in Figure 2(a)), and Figure 4(b) shows the state in which they are in the clamping position (Figure 2(b)).

[0040] The first upper holder 111 is provided with a rectangular conductor holding groove 111A at a position close to one end face (right end face in the figure) 111S in the third direction (the direction of the shorter side of the rectangular conductor; the Z direction in the figure), and the first lower holder 112 is provided with a rectangular conductor holding groove 112A at a position close to one end face (right end face in the figure) 112S in the third direction (hereinafter referred to as the Z direction). The third direction (Z direction) is a different direction from the X direction and the Y direction, and here it is considered to be a direction perpendicular to both.

[0041] One end face 111S of the first upper holder 111 and one end face 112S of the first lower holder 112 are assumed to be located on the same plane. In Figure 1, one end face in the third direction (Z direction) refers to the front faces of the first upper holder 111 and the first lower holder 112, and is the end face closest to the worker.

[0042] The rectangular conductor holding grooves 111A and 112A are rectangular grooves provided on the inner side of the first upper holder 111 and the first lower holder 112, at a distance d1 in the third direction (Z direction), and on the opposing surfaces OS1 of the first upper holder 111 and the first lower holder 112.

[0043] Furthermore, as will be explained in detail later, the rectangular conductor holding grooves 111A and 112A need to securely hold (clamp) the rectangular conductor. For this reason, their shape follows the outer shape of the rectangular conductor, and the depth d3 of each groove is less than half the thickness d2 of the rectangular conductor being clamped (in this case, the first rectangular conductor C1). Specifically, the depth of the rectangular conductor holding grooves 111A and 112A is about 5 / 100 mm less than half the thickness d2 of the rectangular conductor.

[0044] As shown in Figure 2(b), when the opposing surfaces OS1 of the first upper holder 111 and the first lower holder 112 come into contact (when they are in the clamping position (Figure 2(b))), the rectangular conductor holding grooves 111A and 112A become a single prismatic hole that penetrates the first holding part 11 in the X direction. The rectangular conductor (first rectangular conductor C1) is compressed in the direction of the plate thickness d2 (its plate thickness is reduced) and comes into close contact with the rectangular conductor holding grooves 111A and 112A, and is clamped by the first holding part 11 (first upper holder 111 and first lower holder 112).

[0045] Although not shown in the diagram here, the same applies to the second holding part 12. The second upper holding body 121 is provided with a rectangular conductor holding groove 121A at a position close to one end face (the front face closer to the worker) in the third direction (Z direction), and the second lower holding body 122 is provided with a rectangular conductor holding groove 122A at a position close to one end face in the third direction. The configuration of the rectangular conductor holding grooves 121A and 122A is the same as the configuration of the rectangular conductor holding grooves 111A and 112A of the first holding part 11.

[0046] The first holding part 11 and the second holding part 12 are in one of the following states: clamping state, pressure contact state, pressure release state, retraction state, or a transition state between two of these states.

[0047] Referring again to Figures 2 and 3, in the clamping state, the first upper holder 111 and the first lower holder 112 of the first holding part 11 are moved along the Y direction from a Y-spaced position (Figure 2(a)) to a clamping position (Figure 2(b)), causing the first rectangular conductor C1 to be clamped between the first upper holder 111 and the first lower holder 112. At the same time, the second upper holder 121 and the second lower holder 122 of the second holding part 12 are moved along the Y direction from a Y-spaced position (Figure 2(a)) to a clamping position (Figure 2(b)), causing the second rectangular conductor C2 to be clamped between the second upper holder 121 and the second lower holder 122.

[0048] As previously described, the first holding portion 11 clamps the first rectangular conductor C1 so that it protrudes from the opposing surface OS2 along the Y direction toward the second holding portion 12 by an amount A1, and the second holding portion 12 clamps the second rectangular conductor C2 so that it protrudes from the opposing surface OS2 along the Y direction toward the first holding portion 11 by an amount A2.

[0049] At this time, the pressing part 18 (see Figure 1(a)) presses the first upper holder 111 and the first lower holder 112 so that they come into contact with each other, and presses the second upper holder 121 and the second lower holder 122 so that they come into contact with each other. As a result, the first rectangular conductor C1 and the second rectangular conductor C2 are compressed in the thickness direction (their thickness is reduced) and come into close contact with the rectangular conductor holding grooves 111A, 112A, 121A, and 122A, and are held between the first holding part 11 and the second holding part 12 (see Figure 4).

[0050] In addition, in the clamped state, the first upper holder 111 and the first lower holder 112 of the first holding part 11, which are in the Y-direction release position (Figure 2(c)), are moved to the clamping position (Figure 2(b)) to clamp the first rectangular conductor C1 between the first upper holder 111 and the first lower holder 112, and the second upper holder 121 and the second lower holder 122 of the second holding part 12, which are in the Y-direction release position (Figure 2(c)), are moved to the clamping position (Figure 2(b)) to clamp the second rectangular conductor C2 between the second upper holder 121 and the second lower holder 122.

[0051] In this case as well, the pressing part 18 presses the first upper holder 111 and the first lower holder 112 so that they come into contact with each other, and presses the second upper holder 121 and the second lower holder 122 so that they come into contact with each other. As a result, the first rectangular conductor C1 and the second rectangular conductor C2 are compressed in the thickness direction (their thickness is reduced) in the hole and come into close contact with the rectangular conductor holding grooves 111A, 112A, 121A, and 122A, and are held between the first holding part 11 and the second holding part 12 (Figure 4).

[0052] In the compressed state, the first holding part 11 and the second holding part 12, which are in a clamped state, move along the X direction from a position separated in the X direction (Figure 2(a)) to a position close together (Figure 3(a)) against the biasing force of the biasing member 15. At this time, the first rectangular conductor C1 protrudes from the first holding part 11, and the second rectangular conductor C2 protrudes from the second holding part 12. The amounts of these protrusions A1 and A2 are each slightly longer than the length by which the opposing end faces in the longitudinal direction of the band come into contact when the first holding part 11 and the second holding part 12 are in the close-to-close position (Figure 3(a)). In other words, the opposing end faces of the first rectangular conductor C1 and the second rectangular conductor C2 first come into contact (abut) before moving to the close-to-close position. Subsequently, the first holding part 11 and the second holding part 12 move to a close position (Figure 3(a)), causing the contacting end faces of the first rectangular conductor C1 and the second rectangular conductor C2 to abut and press against each other, thereby joining them together. More specifically, by pressing the end faces of the first rectangular conductor C1 and the second rectangular conductor C2 against each other, the stable oxide film formed on the end faces is removed, and these are plastically deformed to expose the active surfaces. By bringing these active surfaces closer together to less than 10 angstroms, atomic bonding between the metals is induced, and cold pressure welding is performed. In other words, due to cold pressure welding, the length of the first rectangular conductor C1 and the second rectangular conductor C2 in the longitudinal direction is compressed (shortened) after welding compared to before welding. The amount of shortening is the same for both the first rectangular conductor C1 and the second rectangular conductor C2. In other words, if the length of the first rectangular conductor C1 before compression welding was L01 and the length of the second rectangular conductor C2 before compression welding was L02, then compression welding shortens the length of the first rectangular conductor C1 to L01' and the length of the second rectangular conductor C2 to L02', and the amount of shortening S is the same for both (S = L01 - L01' = L02 - L02').

[0053] Furthermore, once they have moved to a close position, the first holding part 11 and the second holding part 12 will not come any closer together, so any further pressing between the end faces of the first rectangular conductor C1 and the second rectangular conductor C2 will cease.

[0054] Furthermore, in the pressure-welded state, the first upper holder 111 and the first lower holder 112, and the second upper holder 121 and the second lower holder 122, which are in the Y-direction release position (Figure 2(c)) or the Y-direction release position and the X-direction release position (Figure 3(b)), are moved to the clamping position (Figure 2(b)), and the first holding part 11 and the second holding part 12 are moved to a close position against the biasing force of the biasing member 15, so that the end face of the first rectangular conductor C1 and the end face of the second rectangular conductor C2 are butted and pressed together to perform cold pressure welding (Figure 3(a)).

[0055] In the pressure-release state, the first retaining part 11 and the second retaining part 12, which are in the pressure-release state, are moved in a direction that separates them along the X direction, moving the first retaining part 11 and the second retaining part 12 to the X-direction release position. In addition, the first upper retaining body 111 and the first lower retaining body 112 are moved in a direction that separates them along the Y direction, moving the first upper retaining body 111 and the first lower retaining body 112 to the first Y-direction release position. In addition, the second upper retaining body 121 and the second lower retaining body 122 are moved in a direction that separates them along the Y direction, moving the second upper retaining body 121 and the second lower retaining body 122 to the second Y-direction release position (Figure 3(b)).

[0056] In the compressed state, the first holding part 11 and the second holding part 12 eventually reach a close position, and further pressing of the first rectangular conductor C1 and the second rectangular conductor C2 stops. Therefore, in order to repeat pressing, the state transitions from the compressed state to the released state and then to the clamped state, and the first rectangular conductor C1 and the second rectangular conductor C2 are clamped again by the first holding part 11 and the second holding part 12.

[0057] In this case, when the pressure contact state changes to a release state (when the pressure contact is released), the biasing member 15 exerts a biasing force in the direction that separates the first upper holder 111 and the first lower holder 112 (and similarly the second upper holder 121 and the second lower holder 122). However, as shown in Figure 4, there is almost no clearance between the rectangular conductor holding grooves 111A, 112A, 121A, and 122A and the first rectangular conductor C1 and the second rectangular conductor C2. Furthermore, some of the metal that has flowed due to the plastic deformation of the metal by pressing (the expanded joint surface) enters the small clearances of the rectangular conductor holding grooves 111A, 112A, 121A, and 122A (for example, the corners of the grooves), increasing the degree of adhesion. As a result, the biasing force of the biasing member 15 alone may not be able to separate the first upper holder 111 and the first lower holder 112 (the same applies to the second upper holder 121 and the second lower holder 122).

[0058] Therefore, in this embodiment, in the pressure release state (Figure 3(b)), in addition to the biasing force of the biasing member 15, the first holding part (first upper holding body 111 and first lower holding body 112) is moved along the X direction away from the second holding part 12 to return to the first X direction release position, and the second holding part (second upper holding body 121 and second lower holding body 122) is moved along the X direction away from the first holding part 11 to return to the second X direction release position.

[0059] Furthermore, even when the first holding portion 11 and the second holding portion 12 are forcibly moved in a direction that separates them, in addition to the biasing member 15, the first rectangular conductor C1 and the second rectangular conductor C2 are restricted from moving apart from each other along the X direction by a movement restricting means (not shown).

[0060] In the retracted state, the first holding part 11 and the second holding part 12, which are in a pressed state, a released state, or a clamped state, are moved along the X direction to a position separated in the X direction, and the first upper holding body 111 and the first lower holding body 112 are moved along the Y direction to a position separated in the Y direction, and the second upper holding body 121 and the second lower holding body 122 are moved along the Y direction to a position separated in the Y direction (Figure 2(a)).

[0061] The cold welding apparatus 10 can cold-weld rectangular conductors with a single press, but to stabilize the joint surface, it is desirable to repeat the pressing process multiple times for each joint. For example, the amount of pressing (compression) in one go by the cold welding apparatus 10 is about 0.5 mm for both the first rectangular conductor C1 and the second rectangular conductor C2. Then, by repeating the pressing (cold welding) process three to four times for each joint, and compressing it to about 1 mm or more (preferably 1.5 mm or more, specifically about 2 mm), a stable joint surface can be obtained.

[0062] Therefore, the cold welding apparatus 10 of this embodiment repeatedly performs cold welding of the first rectangular conductor C1 and the second rectangular conductor C2 by repeatedly switching between a clamping state, a welding state, and a release state.

[0063] As shown in Figure 3(a), after being clamped, the first holding part 11 and the second holding part 12 move to a close position, and the end faces of the first rectangular conductor C1 and the second rectangular conductor C2 come into contact (rub against each other), and are pressed together and cold-press welded. The first holding part 11 and the second holding part 12, which are in a close position, cannot get any closer, so they transition to a release position (Figure 3(b)), moving the first holding part 11 and the second holding part 12 to a release position in the Y direction to release the clamping of the rectangular conductors, and moving the first holding part 11 and the second holding part to a release position in the X direction. Then, they transition to a clamping position, holding the first rectangular conductor C1 in the first holding part 11 so that a predetermined protrusion amount A1 protrudes, and holding the first rectangular conductor C2 in the second holding part 12 so that a predetermined protrusion amount A2 protrudes, and then transition to a press-fit state again, so that multiple pressing operations can be repeated for one joint.

[0064] In other words, the release position in the X direction is a position in which the first holding part 11 can hold the first rectangular conductor C1 with a protrusion amount A1, and the second holding part 12 can hold the second rectangular conductor C2 with a protrusion amount A2.

[0065] Note that the release position in the X direction does not necessarily have to be the position where, if the clamping state is then transitioned to, each of the rectangular conductors protrudes by protrusion amounts A1 and A2. In that case, the first holding part 11 and the second holding part 12 should be moved to a position where, in the clamping state, each of the rectangular conductors protrudes by protrusion amounts A1 and A2, and then the clamping should be performed.

[0066] Furthermore, in the above embodiment, a configuration in which the first holding part 11 and the second holding part 12 stop at the X-direction release position and the Y-direction release position in the pressure release state was described as an example, but the X-direction release position and the Y-direction release position may be passed over without stopping at these positions. In other words, the first upper holding body 111 and the first lower holding body 112 (and the second upper holding body 121 and the second lower holding body 122) may move without stopping between the clamping position, the Y-direction release position and the Y-direction separation position, and the first holding part 11 and the second holding part 12 may move without stopping between the proximity position, the X-direction release position and the X-direction separation position.

[0067] Conventionally, cold pressure welding has been used to join round wires together, but with the cold pressure welding apparatus 10 of this embodiment described above, good and stable cold pressure welding can be performed on flat conductors together.

[0068] Furthermore, by using coil pieces as rectangular conductors (first rectangular conductor C1, second rectangular conductor C2), the cold welding apparatus 10 can be used as a coil manufacturing apparatus 20. This will be explained below.

[0069] <Coil Manufacturing Equipment> <Coil manufacturing equipment / Rectangular conductor (coil piece)> First, the rectangular conductor C used in the coil manufacturing apparatus 20 of this embodiment will be described with reference to Figure 5. Figure 5 is a top view of the wide surface WS of the rectangular conductor C. The rectangular conductor C is a plurality of strip-shaped rectangular conductors that are straight (Figure (a)) or have at least one bent portion (Figures (b) to (e)), and can form a spiral shape when connected together. Hereinafter, these will be referred to as coil pieces. The coil pieces having bent portions are bent in the same direction along the longitudinal direction of the strip so that they form a spiral shape when connected together. In the case of coil pieces having bent portions, it is preferable that the bent portion has at least one non-curved shape (for example, approximately right angle).

[0070] Furthermore, in the following explanation, a spiral structure formed by connecting multiple coil pieces (flat rectangular conductors) in a continuous manner is defined as a coil (a spiral structure intended to be completed), and the spiral structure before completion is also included as a coil piece. In other words, in the following explanation, a coil piece (flat rectangular conductor) includes the smallest unit coil piece that is linear or has a bend in the same direction along the longitudinal direction of the band (1 to 4), and a coil piece formed by connecting multiple such smallest unit coil pieces to create a spiral structure that goes around at least one turn of the coil (a spiral structure intended to be completed). Also, for the sake of explanation, when it is necessary to distinguish between these, the smallest unit coil piece will be called a unit coil piece, a coil piece formed by connecting multiple unit coil pieces and not yet intended to be completed as a coil (a spiral structure intended to be completed) will be called a joined coil piece, and the spiral structure intended to be completed (in its completed state) will be called a coil. Furthermore, it will be assumed that the shape and area of ​​the cross-section perpendicular to the longitudinal direction of the band are all approximately the same for multiple coil pieces.

[0071] As shown in the figure, a unit coil piece C0 is constructed, for example, by punching out a copper plate (for example, 1 mm thick) to form a straight or nearly right-angled, non-curved bend (corner). In other words, when viewed from above on the wide surface WS, a unit coil piece C0 can be straight (I-shaped) without a bend (Figure (a)), L-shaped with one bend (Figure (b)), U-shaped with two bends (Figure (c)), nearly C-shaped with three bends (Figure (d)), or C-shaped with four bends that all bend in the same direction (nearly O-shaped (nearly U-shaped)) (Figure (e)). In the following explanation, we will use U-shaped, (negatively) C-shaped, and nearly O-shaped, but in all cases, the bend (corner) will be approximately right-angled.

[0072] Furthermore, the preparation length L0 of the multiple coil pieces (unit coil pieces and / or joined coil pieces) is set to be longer than the final length in the helical longitudinal direction of the planned helical structure (coil) by a margin. This margin is set to the total shortening distance that will occur due to the pressing when all of the multiple coil pieces are cold-press welded. The preparation length L0, final length, margin, and total shortening distance will be explained in detail in the coil manufacturing method described later.

[0073] <Coil Manufacturing Equipment / Holding Section> Since the coil manufacturing apparatus 20 of this embodiment is an example of using the cold welding apparatus 10 described above, components similar to those of the cold welding apparatus 10 are indicated by the same reference numerals, and redundant explanations are omitted. In the following description, we will mainly describe components that are suitable for use in the coil manufacturing apparatus 20.

[0074] Referring again to Figure 1, the coil manufacturing apparatus 20 comprises a first holding part 11 and a second holding part 12, which are arranged opposite to each other and capable of holding one rectangular conductor and another rectangular conductor, respectively, and forms a spiral structure by joining together a plurality of strip-shaped rectangular conductors (coil pieces) that can form a spiral shape when connected. The preparation length, which is the total distance in the longitudinal direction of the plurality of rectangular conductors (coil pieces), is set to be longer by a margin compared to the completed length in the longitudinal direction of the spiral structure to be completed. The end faces of the plurality of rectangular conductors (coil pieces) are pressed together along the longitudinal direction of the strip and cold-press welded while shortening the distance in the longitudinal direction of the strip, and the spiral structure is formed by setting the total shortening distance of all the plurality of rectangular conductors (coil pieces) shortened by cold-press weld as a margin.

[0075] In other words, in the coil manufacturing apparatus of this embodiment, as the number of times coil pieces are joined increases, the length of the coil pieces (joined coil pieces) held by the first holding part 11 or the second holding part 12 increases. For this reason, the configuration of the first holding part 11 and the second holding part 12 is suitable for use in the manufacture of coils.

[0076] First, Figure 6 is a schematic diagram of a coil piece in the process of being manufactured by the coil manufacturing apparatus 20. Figure (a) is a schematic diagram (top view) of a prepared unit coil piece, Figures (b) to (d) are unfolded views of the unit coil piece and joined coil piece in the process of being manufactured, and Figure (e) is a view in the direction of the arrow in the V direction of Figure (d).

[0077] Here, as an example, we show a case where multiple (in this case, four) U-shaped (or U-shaped) unit coil pieces C0, each having two bends, are prepared and connected (connected) to manufacture a coil (spiral structure) 50 consisting of two turns in a spiral shape. The dashed lines at both ends of the coil pieces in Figures (b) to (d) indicate the finished ends of the completed coil, and in this example, it is assumed that the finished ends do not change (the position of the finished ends does not move in the left-right direction shown in the figure).

[0078] First, in the initial cold welding, as shown in Figure (b), one end face (indicated by a circle) of each of the two unit coil pieces C01 and C02 is connected to form a joined coil piece CC1. Then, in the next cold welding, one end face of the joined coil piece CC1 (either the unjoined end face of unit coil pieces C01 or C02) is cold-welded to unit coil piece C03 to form a joined coil piece CC2 (Figure (c)). Finally, in the next cold welding, one end face of the joined coil piece CC2 (either the unjoined end face of unit coil pieces C01 or C03) is cold-welded to unit coil piece C04 to complete coil 50 (Figure (d)).

[0079] In other words, the first holding part 11 or the second holding part 12 holds a bent (in this case, U-shaped) coil piece, and the sequentially lengthening spiral connecting coil pieces CC1, CC2, etc. are located near the first holding part 11 or the second holding part 12. Therefore, the first holding part 11 and the second holding part 12 must be configured to avoid interference with these coil pieces.

[0080] Figure 7 illustrates the configuration of the first holding part 11. Figure 7(a) shows a state in which one unit coil piece C0 is held by the first holding part 11 (first upper holder 111 and first lower holder 112), and is a front view of the surface OS2 facing the second holding part 12. Figure 7(b) is a front view of the completed coil 50 viewed from the direction of the axis center of the helical structure, and the coil piece in Figure 7(a) corresponds to the cross-sectional view along line BB in Figure 7(b). Although the first holding part 11 is described here, the same applies to the second holding part 12. Figure 7(c) is a front view of the first holding part 11 (cross-sectional view along line AA in Figure 7(a)).

[0081] As shown in Figures (a) and (b), when a coil piece has two or more bends (for example, a U-shaped coil piece), there is a risk of interference between the first holding part 11 and the coil piece other than the joined coil piece (Figure (a)), where the coil piece C0' extending towards the front after making a U-turn from the coil piece C0 held by the first holding part 11 may interfere. In this embodiment, in order to avoid this, the dimensions of the first holding part 11 and the coil piece (the coil 50 to be completed) are configured to satisfy the following relationship.

[0082] In other words, when connecting U-shaped (or U-shaped) coil pieces, one of the first holding parts 11, specifically, one end face 111S of the first upper holding body 111 and one end face 112S of the first lower holding body 112 which is on the same plane as the first upper holding body, and the end face perpendicular to the opposing surface OS2, is located in the internal space of the helical structure (including the space that is to become the internal space of the helical structure) (hereinafter, this end face is referred to as the internal helical end face IS). The internal helical end face IS is, for example, the front of the first holding part 11 that is close to the worker.

[0083] Therefore, in order to avoid interference between the first retaining portion 11 and the coil piece, it is necessary to provide the rectangular conductor retaining grooves 111A and 112A of the first retaining portion 11 in appropriate positions, and the distance d1 from the internal end face IS of the spiral to the end of the nearest rectangular conductor retaining groove 111A or 112A (the upper end in the figure) shall be smaller than the distance D1 of the internal space of the spiral structure (coil 50) along the third direction (the Z direction in the figure: the direction of the shorter side of the coil piece to be cold-welded).

[0084] Furthermore, the length d4 of the first holding portion 11 in the X direction (Figure (c)) is set to be smaller than the distance D2 of the internal space of the helical structure (coil 50) along the X direction (Figure (b)).

[0085] After cold-press welding the two coil pieces, burrs 55 are generated at the connection point due to extrusion. Therefore, after cold-press welding is completed, the coil pieces (joined coil pieces) are removed from the first holding part 11 and the second holding part 12, deburred, and then cold-press welding is performed between the said coil piece (joined coil piece) and the other (new) coil piece.

[0086] Figure 8 is a diagram corresponding to Figure 7(a) (viewed from the same direction) and shows the state in which the joined coil piece CC is formed. In the coil manufacturing apparatus 20 of this embodiment, the joined coil piece CC is formed on one side of the first holding part 11 (similarly the second holding part 12), in this case on the first lower holding body 112 side. On the other hand, since the rectangular conductor holding grooves 111A and 112A of the first holding part 11 are straight grooves along the X direction, during cold pressure welding, only a straight portion including one end face of the joined coil piece CC is held by the first holding part 11. Therefore, in order to avoid interference between the joined coil piece CC and the first holding part 11 (first lower holding body 112), the coil piece (in this case the joined coil piece CC) is subjected to elastic and / or plastic deformation so as to spread in the direction of helical progression of the helical structure (direction along the Y direction), leaving the vicinity of the end face to be cold-pressed, while cold pressure welding is performed between it and the coil piece held by the second holding part 12.

[0087] The amount of deformation D3 of the elastic and / or plastic deformation of the coil piece (here, the joined coil piece CC) in the helical direction is set to an amount that avoids interference between the first holding part 11 and the coil piece. In other words, the length (thickness) d5 along the Y direction of the holder on the side of the first holding part 11 where the joined coil piece is formed (here, the first lower holder 112) is set to be smaller than the amount of deformation D3 that is allowed for the elastic and / or plastic deformation of the coil piece (here, the joined coil piece CC) in the helical direction.

[0088] Thus, the coil manufacturing apparatus 20 of this embodiment forms a helical structure by joining coil pieces together by cold pressure welding while elastically and / or plastically deforming them in the helical direction of progression (along the Y direction). During the manufacturing process, the coil pieces are joined (applied together) in an expanded state in the direction of helical progression. After the helical structure is completed, the helical structure is integrally molded (for example, by pressing), and elastic and / or plastic deformation is performed to compress it in the direction of helical progression to form a coil 50 in which each circumference of the helix is ​​closely joined.

[0089] The coil manufacturing apparatus 20 of this embodiment manufactures a coil of the desired length L by adding coil pieces that are longer (longer to account for the amount of compression (shrinkage) due to cold compression) based on the length of the completed coil, while repeatedly compressing (shrinking) it by cold compression.

[0090] Therefore, during cold welding, the distance between the coil pieces in the longitudinal direction of the strip is measured while performing the cold welding. The distance in the longitudinal direction of the strip can be measured, for example, by providing a slip detection mechanism (not shown) in the first holding part 11 and the second holding part 12 (or nearby), and detecting the slip when the coil piece held by the first holding part 11 (first coil piece) and the coil piece held by the second holding part 12 (second coil piece) are pressed together, thereby measuring the distance in the longitudinal direction of the strip. Note that the distance in the longitudinal direction of the strip may be measured simultaneously with the cold welding (in real time), or before and after the cold welding (or before or after the cold welding). This makes it possible to achieve high precision in the dimensions of the completed coil.

[0091] As shown in Figure 7(b), the nearly right-angle bends of the coil pieces become the corners of the coil 50. In other words, according to the coil manufacturing apparatus 20 of this embodiment, a coil 50 with nearly right-angle corners on both the inner and outer circumferences can be manufactured by joining together coil pieces that have been configured to have nearly right-angle bends by punching or the like. Conventionally, coils made of flat rectangular conductors were manufactured by winding long lengths of flat rectangular conductors, but in winding, it is unavoidable that at least the corners on the inner circumference of the coil will have a curved shape, which limits improvements in space utilization and heat dissipation.

[0092] However, with the coil manufacturing apparatus of this embodiment, since the coils can be joined together while maintaining the shape formed by punching, right-angle (or nearly right-angle) corners can be realized on the inner circumference side of the coil, improving the space utilization ratio, and it is possible to manufacture coils that can improve heat dissipation by eliminating excess space.

[0093] In particular, the joint CP is provided on the straight section, avoiding the bent section (corner). That is, the pressure welding is performed using the straight section of the coil piece. As a result, the shape accuracy of the bent section can be improved, and for example, the corners formed at a right angle (or nearly right angle) during the punching process can be maintained.

[0094] <Coil Manufacturing Method> Next, the coil manufacturing method of this embodiment will be described. The coil manufacturing method of this embodiment can be implemented, for example, in the coil manufacturing apparatus 20 described above.

[0095] In other words, the coil manufacturing method of this embodiment involves preparing multiple strip-shaped rectangular conductors (coil pieces) that can form a helical structure when connected together, setting the preparation length L0, which is the total length of the multiple rectangular conductors (coil pieces) in the longitudinal direction of the strip, to be longer by a margin M compared to the completed length L in the longitudinal direction of the helical structure (coil) to be completed, pressing the end faces of the multiple rectangular conductors (coil pieces) together along the longitudinal direction of the strip and cold-press welding them while shortening the distance in the longitudinal direction of the strip, and setting the total shortening distance S, which is the shortening of all the multiple rectangular conductors (coil pieces) by cold-press welding, to the margin M, thereby joining the multiple rectangular conductors (coil pieces) to form a helical structure (coil).

[0096] Specifically, referring to Figure 9, we will explain using the example of preparing four U-shaped (C-shaped) unit coil pieces C0 (C01-C04) each having two bends, and connecting them (making them continuous) to manufacture a coil (spiral structure) 50 consisting of two turns in a spiral shape. Similar to Figure 6, Figure (a) is a top view of coil pieces C01-C04, and Figures (b)-(d) are unfolded views of the connecting coil pieces. The dashed lines in the figures indicate the axial center (center of the joint CP) of the spiral structure of the completed coil 50. The dashed lines at both ends of the coil pieces in Figures (b)-(d) indicate the finished ends of the completed coil. In this example, it is assumed that the finished ends do not change (the position of the finished ends does not move in the left-right direction shown in the figure).

[0097] If the lengths of the unit coil pieces C01 to C04 in the longitudinal direction of the band are L01 to L04, then the preparation length L0, which is the total length in the longitudinal direction of the band, is L01 + L02 + L03 + L04. This preparation length L0 is set to be longer by a margin M than the finished length L in the helical longitudinal direction of the coil 50 (L0 = L + M). When these unit coil pieces C01 and C02 are pressed together along the longitudinal direction of the band and cold-press welded, the pressing compresses the length L01 of unit coil piece C01 to L01' (the amount of shortening (compression) is the distance S1 from the center of the joint CP), and the length L02 of unit coil piece C02 is compressed to L02' (the amount of shortening (compression) is the distance S2 from the center of the joint CP), forming a joined coil piece CC1 (length LC1) (Figure (b)). Then, when the end face of joined coil piece CC1 (the end face on the unjointed side of unit coil piece C01 or C02) and unit coil piece C03 are cold-press welded, the pressing compresses the unit coil piece C03 to L03' (the amount of shortening (compression) is the distance S3 from the center of the joint CP), and the joined coil piece CC1 is compressed to LC1' (the amount of shortening (compression) is the length of the joint). A joint coil piece CC2 is formed at a distance S4 from the center of the joint CP (Figure (c)). Furthermore, when the end face of the joint coil piece CC2 (the unjoined end face of the unit coil pieces C01 and C03) and the unit coil piece C04 are cold-press welded, the pressing compresses the unit coil piece C04 to L04' (the amount of shortening (compression) is the distance S5 from the center of the joint CP), and the joint coil piece CC2 is compressed to LC2' (the amount of shortening (compression) is the distance S6 from the center of the joint CP), completing a coil 50 (spiral structure) with a finished length L in the longitudinal direction of the spiral (length from the starting point ST to the ending point SE) (Figure (d)). The total amount of shortening of the coil pieces (total shortening distance S = S1 + S2 + S3 + S4 + S5 + S6) until the coil 50 is completed by joining the coil pieces (unit coil pieces and / or joint coil pieces) corresponds to the margin M.

[0098] The manufacturing method of the coil in this embodiment will now be explained again in chronological order. First, based on the length L of the completed coil 50, the lengths L01 to L04 of the unit coil pieces are set so that the total shortened distance S = margin M, and the compression amounts S1 to S6 by cold welding are also set.

[0099] Then, using the coil pieces configured in this way, the end faces of unit coil pieces C01 and C02 are pressed together by cold welding by predetermined compression amounts S1 and S2 to form a joined coil piece CC1. The compression amounts S1 and S2 at this time are determined by detecting slippage between unit coil pieces C01 and C02 when they are pressed, and measuring the distance between the two coil pieces in the longitudinal direction of the strip. The method for determining the compression amount is the same as in the following cold welding process.

[0100] After cold-press welding one joining area (for example, near the end faces where unit coil pieces C01 and C02 are joined), burrs are formed at the joint due to the pressing action. Therefore, a process to remove the burrs is performed after cold-press welding.

[0101] Next, the coil piece (joining coil piece CC1) is subjected to cold welding with another coil piece (unit coil piece C03) while elastically and / or plastically deforming it in the helical direction of the planned helical structure, leaving the vicinity of the end face to be cold-welded (the unjoined end face of unit coil piece C01 or unit coil piece C02) untouched. At this time, the amount of elastic and / or plastic deformation of the joining coil piece CC1 in the helical direction is set to an amount that avoids interference between the first holding part 11 and the second holding part 12, which hold the coil piece during cold welding, and the joining coil piece CC1. The amount of deformation is similar in the following cold welding processes.

[0102] The coil pieces are then joined in the same manner. Specifically, the end face of joining coil piece CC1 (the unjoined end face of unit coil piece C01 or C02) and unit coil piece C03 are joined by cold welding under set compression amounts S3 and S4 to form joining coil piece CC2. After that, the joining area is deburred, and joining coil piece CC2 is elastically and / or plastically deformed in the direction of the helical progression of the planned helical structure, leaving the vicinity of the end face to be cold-welded, while the end face of joining coil piece CC2 and unit coil piece C04 are joined by cold welding under set compression amounts S5 and S6 to obtain the completed helical structure.

[0103] Figure 10 shows an example of a completed helical structure 50' (the number of coil turns differs from the embodiment described above). Figure 10(a) is a front view seen from the direction of the helical axis, Figure 10(b) is a view in the V direction (side view) before molding, and Figures 10(c) and (d) are side views after molding.

[0104] The completed helical structure 50' is formed by press working or the like. That is, in order to avoid buffering with the first holding part 11 and the second holding part 12 during cold pressure welding, the helical structure is elastically and / or plastically deformed in the direction of helical progression, which creates unnecessary and uneven spreading (space) between each circumference of the helix. Therefore, the helical structure is elastically and / or plastically deformed in the direction of helical progression to compress this, bringing each circumference of the helix as close (close) to each other as possible (Figure (c)).

[0105] Furthermore, if necessary, the spiral structure is formed to be concave or convex in the direction of the axial center of the stator core (radial direction of the stator core), that is, as shown in Figure (d), it is formed into a curved shape in which the inner circumferential end is not flush with the outer circumferential end.

[0106] Subsequently, the molded helical structure is immersed in liquid insulating resin to integrally coat it with insulating resin. Alternatively, the molded helical structure may be integrally coated with insulating resin by spraying it with liquid insulating resin. Conventionally, a long wire equal to the finished length of the coil was coated with insulating resin, and then wound to form a helical structure. However, in this case, the insulating resin stretches near the outer circumference of the curved part of the winding, resulting in a thinner coating thickness and a deterioration in pressure resistance. Also, for example, if the insulating resin is applied before molding as described above, a similar problem occurs because the thickness of the insulating resin coating varies due to pressing. In this embodiment, since the helical structure molded into the shape to be attached to the stator core is integrally coated with insulating resin after molding, the uniformity of the insulating resin film thickness can be improved. Furthermore, because the insulating resin is applied integrally after molding, the helical structures can be bonded together with the insulating resin, and a uniform film thickness can be achieved.

[0107] <Modified form of a coil piece> Figure 11 shows examples of connections when the shape of the coil pieces is different.

[0108] Figure (a) is a top view showing an example of connection using L-shaped coil pieces, where four L-shaped coil pieces C0 are used to form a connecting coil piece for one full turn. For the sake of explanation, the illustration is omitted, but in this case as well, the preparation length L0 of each coil piece, which is the total length in the longitudinal direction of the strip, is set to be longer by a margin M compared to the completed length L in the longitudinal direction of the spiral structure (coil) to be completed. The margin M is set to the total shortening distance S that will be shortened by pressing when all of the coil pieces are cold-press welded.

[0109] Furthermore, it is not necessary to construct all the connecting coil pieces for one full turn in the same shape (L-shape). In other words, you can combine I-shaped (straight) or U-shaped (U-shaped) coil pieces in an L-shape to form the connecting coil pieces for one full turn.

[0110] Figure (b) is a top view showing an example of a connection combining a C-shaped coil piece C0 and an I-shaped coil piece C1. For the sake of explanation, although not shown in the illustration, in this case as well, the preparation length L0 of each coil piece, which is the total length in the longitudinal direction of the strip, is set to be longer by a margin M compared to the completed length L in the longitudinal direction of the spiral structure (coil) to be completed. The margin M is set to the total shortening distance S that will be shortened by pressing when all of the coil pieces are cold-press welded.

[0111] Alternatively, a roughly C-shaped coil piece with three corners and an L-shaped coil piece may be combined to form a connecting coil piece for one full rotation. Furthermore, the coil pieces constituting the first and second rotations of the spiral structure may be different combinations.

[0112] Figure (c) is an unfolded diagram showing the case where a joined coil piece is formed by combining a U-shaped (square-shaped) coil piece C0 with two corners and a coil piece (O-shaped) coil piece C1 that makes up one full turn of the planned helical structure. The dashed lines at both ends of the coil piece in the figure indicate the finished ends of the completed coil, and in this example, it is assumed that the finished ends do not change (the position of the finished ends does not move in the left-right direction shown in the figure).

[0113] The O-shaped coil piece C1 has a cut at the joint. When one end of the U-shaped coil piece C0 and one end of the O-shaped coil piece C1 are cold-press welded, the U-shaped coil piece C0 is compressed by a compression amount S0 and the O-shaped coil piece C1 is compressed by a compression amount S1, and by repeating this process, a helical structure can be formed. Note that in Figure 9, (when U-shaped coil pieces C0 of the same length are used), the joint CP is formed at approximately the same position (overlapping position) along the axis center of the helical structure on each circumference of the helical structure, as shown in the figure. However, in the case of Figure 11(c), the joint CP is formed at a predetermined distance shifted along the axis center (dashed line) of the helical structure on each circumference of the helical structure.

[0114] <Modifications of coils> Figure 12 shows modified examples of a coil manufacturing apparatus and a coil manufacturing method. Figure 12(a) is a schematic diagram of the coil manufacturing apparatus 20', Figure 12(b) is a side view of the coil 50 manufactured thereby, corresponding to Figure 10(c), and Figure 12(c) is a perspective view of the coil 50.

[0115] As shown in Figure (a), the coil manufacturing apparatus 20' includes a plurality of holding units 22, each consisting of the first holding unit 11 and the second holding unit 12 described above. The plurality of holding units 22 (22A to 22E) may each have different widths W (width along the Z direction, width BS in the short-side direction of the rectangular conductor) of the flat rectangular conductor holding grooves 111A, 112A, 121A, and 122A of the first holding unit 11 and the second holding unit 12 (the widths increase (or decrease) sequentially).

[0116] In this way, by using multiple holding units 22 with different widths W of the rectangular conductor holding grooves 111A, 112A, 121A, and 122A, rectangular conductors of different widths (widths WA to WE in the figure) can be joined. That is, by sequentially moving between the multiple holding units 22 and cold-press welding each circumference of the spiral structure with a different holding unit 22, a spiral structure can be formed in which each circumference of the coil has a different length. That is, by using U-shaped (or U-shaped) unit coil pieces of the same length in the longitudinal direction of the band and sequentially moving between the multiple holding units 22 and cold-press welding to connect the coil pieces, a coil 50 having the shape of a truncated square pyramid (Figures (b) and (c)) can be formed.

[0117] Furthermore, multiple holding units 22 with different depths d3 of the rectangular conductor holding grooves 111A, 112A, 121A, and 122A may be used. In that case, the plate thickness of each circumference of the helical structure constituting the coil 50 can be made different.

[0118] <coil> Next, the coil of this embodiment will be described with reference to Figure 13. Figure 13(a) is a front view of the helical structure as seen from the axial center direction, and Figure 13(b) is a cross-section of Figure 13(a) along line AA. Figure 13(c) is a side view of Figure 13(a) as seen from direction V.

[0119] The coil 50 of this embodiment consists of a helical structure formed by continuously arranging strip-shaped flat rectangular conductors (coil pieces) in a spiral shape, and as shown in Figure (a), the helical structure has non-curved corners (approximately right-angle corners) 50C on the inner and outer circumferences. Here, as an example, it is manufactured using the coil manufacturing apparatus and coil manufacturing method described above.

[0120] In conventional coils constructed by winding long, flat conductors that are longer than one turn of the helical structure of a finished coil, it is unavoidable that the bent sections will have a curved structure, creating large gaps when mounted on the stator core. These gaps have a high heat retention effect, limiting the improvement of the coil's heat dissipation. Furthermore, when long, flat conductors are coated with insulating resin before winding, the thickness of the insulating resin coating becomes thinner at the bent sections, leading to a problem of degraded voltage resistance.

[0121] In contrast, the coil 50 of this embodiment can be formed by punching out the shape of one full turn of the coil's helical structure, thus enabling the formation of a coil with a desired shape in a front view. In other words, a coil 50 can be obtained that follows the shape of the stator core and is as close as possible to it (at least the inner circumference corners 50C are right angles or nearly right angles). As a result, unlike wound coils, the space between the coil and the stator core 60 (shown by a dashed line in Figure (a)) can be minimized. For example, the length of the space per side of the coil 50 (the distance from the inner circumference of the coil 50 to the stator core 60) can be reduced to 0.5 mm to 1.0 mm, thereby improving heat dissipation. Furthermore, since the insulating resin can be applied uniformly over the entire coil 50, deterioration of the voltage resistance due to variations in the thickness of the insulating resin can be suppressed.

[0122] Furthermore, in this embodiment, the coil 50 has a width (width W1 in the short-side direction of the coil piece) perpendicular to the spiral direction of the helical structure, which widens to a width W2 at the corners, thus also reducing the coil resistance.

[0123] Furthermore, because cold welding involves atomic bonding of metals, the connection is so secure that it is virtually invisible. This dramatically improves the stability of the connection compared to configurations where a coil of one turn (or less) is joined planarly with adhesive (such as a bonding agent or brazing).

[0124] Furthermore, as shown in Figure (b), the first circumference of the spiral structure (for example, the first circumference formed by the connecting coil piece CC1) has a first thin-walled section T1 in which the thickness D8 is thinner than the thickness D7 of the flat rectangular conductor (coil piece) in the other parts. Also, the second circumference continuous with the first circumference (for example, the second circumference formed by the connecting coil piece CC2) has a second thin-walled section T2 in which the thickness D8 is thinner than the thickness D7 of the flat rectangular conductor (coil piece) in the other parts.

[0125] As previously described, during cold welding, the coil piece is held between the first holding section 11 and the second holding section 12 of the coil manufacturing apparatus 20. At this time, the total depth of the rectangular conductor holding grooves 111A and 112A (and similarly the total depth of the rectangular conductor holding grooves 121A and 122A) is smaller than the thickness D7 of the coil piece. When the coil piece is pressed by the pressing section 18 and held between the first holding section 11 and the second holding section 12, the held portion is compressed in the thickness direction to a thickness (D8) approximately the same as the total depth of the rectangular conductor holding grooves 121A and 122A, and the rectangular conductor holding grooves 111A and 112A. This held portion by the first holding section 11 and the second holding section 12 is the first thin-walled portion T1 and the second thin-walled portion T2. In other words, the first thin-walled portion T1 and the second thin-walled portion T2 are formed in correspondence with the cold-pressure-welded joint CP. For example, in the case of a coil made by connecting U-shaped coil pieces, the first thin-walled portion T1 is provided at two locations on the first circumference, and the second thin-walled portion T2 is also provided at two locations on the second circumference. Furthermore, if the lengths of all U-shaped unit coil pieces are the same, the first thin-walled portion T1 and the second thin-walled portion T2 are provided in positions that overlap in the direction of the axial center of the helical structure, as shown by the dashed rectangle.

[0126] Furthermore, the first thin-walled portion T1 and the second thin-walled portion T2, which are formed in correspondence with the cold-pressure-welded joint CP, are formed at alternately offset positions on the first and second circumferences corresponding to the joint CP, as shown in Figure 11, when the coil piece is composed of a combination of U-shaped and O-shaped pieces (in the case of an O-shaped coil piece, a thin-walled portion is formed at only one location per circumference).

[0127] Furthermore, the entire circumference of the coil 50, which constitutes the helical structure, is integrally covered with insulating resin. This improves the adhesion between each circumference of the helical structure. In addition, a gap SP of the coil piece is formed between the first thin-walled portion T1 and the second thin-walled portion T2, and a portion of the insulating resin is also embedded in this gap SP. In other words, as explained in the manufacturing method described above, after the completion of the helical structure (molding is performed as necessary), the helical structure is immersed in liquid insulating resin, so the insulating resin enters the gap SP. This further improves the adhesion between each circumference of the helical structure.

[0128] Furthermore, the coil 50 may be formed in a curved shape such that it is concave or convex in the direction of the axial center of the helical structure (radial direction of the stator core) to match the shape of the stator core 60, that is, as shown in Figure (c), the inner circumferential end is not flush with the outer circumferential end.

[0129] Figure 14 shows a comparison of the heat generated by the coil 50 of this embodiment and a coil constructed by winding round wire (round wire coil). The heat generated (temperature) over time was measured for both the round wire coil and the coil 50 of this embodiment at 5V and 20A.

[0130] The temperature of the round wire coil rose rapidly, reaching 28.5°C in 10 seconds and 42°C in 30 seconds, and then rose to 73°C after 90 seconds, so the experiment was stopped. On the other hand, the temperature of coil 50 (20A) in this embodiment rose slowly, reaching 21.1°C in 10 seconds and 21.5°C in 30 seconds, and reached a saturated state of 32.4°C after 1530 seconds.

[0131] As is clear from these results, the coil 50 of this embodiment (a coil with an inner circumference that is approximately perpendicular (inner circumference right-angle coil)) hardly rises above room temperature (for example, 40°C to 50°C) even during operation, indicating extremely high heat dissipation. And due to this high heat dissipation, the coil resistance can be significantly reduced compared to conventional coils.

[0132] Furthermore, the width W3 of the starting and ending portions of the spiral structure of the coil 50 may be wider than the width W1 in the short-side direction of the band. This reduces the coil resistance at the starting and ending portions, similar to the corners.

[0133] In this embodiment, a coil 50 perpendicular to the inner circumference was described, formed by repeatedly joining the end faces of coil pieces by cold pressure welding. However, the coil pieces are not limited to this, and the end faces may be joined by other joining methods. Specifically, various connection methods such as ultrasonic welding (high-frequency welding), electric welding, and brazing can be employed.

[0134] <How to attach to the stator core> Referring to Figure 15, an example of mounting the coil 50 of this embodiment to the stator core will be described. Figure 15(a) is a side view of the coil 50 and cassettes 51A and 51B. Figure 15(b) is a cross-sectional view along the cc line in Figure 15(a). Figure 15(c) is a cross-sectional view corresponding to the cross-section along the cc line in Figure 15(a), showing an example of mounting to the stator core 60.

[0135] The coil 50 of this embodiment is molded to conform to the outer shape of the stator core as shown in Figure 13(c), and after molding, it is integrally covered with insulating resin, and is attached to the stator core in a so-called retrofit manner.

[0136] For this reason, as shown in Figure (a), two cassettes 51A and 51B are prepared, each having flanges 52A and 52B on one side of the spiral structure of the coil 50 in the direction of the axial center. The coil 50 is inserted from the side of one cassette 51A where the flange 52A is not formed, and the other cassette 51B is placed on top of it and engaged. Then this coil 50 with cassettes is inserted into the stator core 60. Cassettes 51A and 51B are provided with notches or engaging portions 53 so that they fit together in a top view of the cross-section shown in Figure (b).

[0137] As shown in Figure (c), the coil 50 may be mounted on a single cassette 51C having a flange 52B on only one side in the direction of the axial center of the helical structure, and then mounted on the stator core 60. In this case, in order to prevent the coil 50 from coming off the stator core 60 due to centrifugal force during operation (or causing unnecessary movement (vibration)), a notch 61 is provided in the stator core 60, and after the cassette-equipped coil 50 is mounted on the stator core 60, a retaining ring 62 covering the top of the cassette-equipped coil 50 is fitted into the notch 61 of the stator core 60.

[0138] <Helical structure of a coil> The spiral structure of the coil will be further described with reference to Figures 16 and 17. Figure 16 is a side view of the coil 50 of this embodiment, where (a) is a side view of one embodiment seen from the short side, (b) is a side view seen from the long side, (c) is a side view of another embodiment seen from the short side, (d) is a side view seen from the long side, and (e) is a side view of yet another embodiment seen from the short side. Figure 17 is a modified example of Figures 16(c) and (e), where Figures 17(a) and (c) are external perspective views, and Figures 17(b) and (d) are side views taken along the arrows in Figures 17(a) and (c), respectively.

[0139] For example, when forming a helical structure by connecting multiple U-shaped (or U-shaped) unit coil pieces as shown in Figure 6, as shown in Figures 16(a) and (b), the thickness of the unit coil piece is absorbed by gradually deforming it along the direction of spiral progression over one full turn from the first circumference TC1 to the second circumference TC2, and this process is repeated for each turn.

[0140] In other words, in one embodiment of this design, the coil 50 is formed by each coil piece being slightly inclined as it connects to the next coil piece, as shown in Figures (a) and (b), thus creating a helical structure. Although Figures (a) and (b) show one side of the coil 50 on the shorter side, all four sides of the coil 50 are similarly inclined.

[0141] Furthermore, the coil 50 of this embodiment is not limited to the structure described above, but may also have a helical structure as shown in Figures (c) to (e).

[0142] In other words, as shown in Figure (c), a portion of the first circumference TC1 of the spiral structure is deformed so that a step B equal to the thickness of the coil piece is created along the direction of spiral progression, and a portion of the second circumference TC2 of the spiral is deformed so that a step B equal to the thickness of the coil piece is created along the direction of spiral progression, and this is repeated to form the spiral structure. Note that the location where this step B is formed is only on one side of the coil 50 (for example, one side on the short side), and the step B of the second circumference is formed on top of the step B of the first circumference at the same location.

[0143] In this way, the thickness of the coil piece is absorbed by the step B formed on just one side, so the other three sides are stacked almost horizontally without each coil piece being inclined, as shown in the side view of the long side in Figure (d).

[0144] With this configuration, the starting end SE and ending end EE of the coil 50 do not protrude, and the outermost surface of the coil can be made flat. In other words, in the helical structure of Figures (a) and (b), as shown in Figure (a), the surface of the coil 50 including the starting end SE (the lower end surface shown) has a step between the coil surface SF12' of the starting end SE and the opposing coil surface SF11' that wraps around it, and they are not on the same plane. Similarly, the surface of the coil 50 including the ending end EE (the upper end surface shown) has a step between the coil surface SF21' of the ending end EE and the opposing coil surface SF22', and they are not on the same plane. When the thickness of the coil piece is relatively thin, such a step does not pose much of a problem. However, when the coil piece is thick, it is necessary to secure space for this step difference when setting it in the cassettes 51A and 51B as shown in Figure 15. In addition, problems such as the coil 50 rattling may occur due to the gap.

[0145] In contrast, in the helical structure shown in Figures (c) and (d), the surface of the coil 50 including the starting end SE (the lower end surface shown) is on the same plane as the coil surface SF12 of the starting end SE and the opposing coil surface SF11 that wraps around it. The surface of the coil 50 including the ending end EE (the upper end surface shown) is on the same plane as the coil surface SF21 of the ending end EE and the opposing coil surface SF22. This allows for a reduction in the outer size of the coil 50 and improves its contact with the cassettes 51A and 51B.

[0146] Figure (e) shows another example of a spiral structure similar to those in Figures (c) and (d), but with a different shape for the coil pieces. The coil pieces may have a cross-section (omitted) that is approximately square in shape, with the width W and thickness d2 in the short-side direction BS being roughly equal, as shown in Figure (e). When the thickness d2 is larger than the width W, it is more preferable to adopt a spiral structure with a step B on one side of the coil 50, as shown in Figure (e).

[0147] Figure 17 shows another embodiment of this design. As shown in the figure, all the coil pieces constituting the coil 50 (all the coil pieces connected along the spiral direction) may have different widths W and thicknesses d2 in the short-side direction BS. For example, in the coil 50 shown in the figure, coil pieces are connected such that the width W of each coil piece gradually widens (WA, WB...) and the thickness d2 gradually decreases from the starting end SE to the ending end EE.

[0148] Furthermore, this example is not limited to this one; the configuration may also involve only the width W of each coil piece being different (changing), or only the thickness d2 of each coil piece being different (changing).

[0149] In this way, the desired truncated square pyramidal coil 50 can be manufactured. Furthermore, as in this example, when using multiple coil pieces with different thicknesses d2, adopting a helical structure as shown in Figure 16(a) results in differences in the step height of the outermost coil surface (the upper outermost and lower outermost edges shown) at the starting end SE and ending end EE due to the difference in the thickness d2 of the coil pieces. As a result, the outer dimensions of the coil 50 become larger and the shape becomes non-uniform (asymmetrical), requiring additional space to be secured in the cassettes 51A and 51B. It also increases the likelihood that secure mounting to the cassettes 51A and 51B will become difficult. In such cases, by creating a helical structure with a step B on one side of the coil 50, even if the thickness d2 of each coil piece is different, the outermost coil surface can be made flat (coil surfaces SF11 and SF12 can be made on the same plane, and coil surfaces SF21 and SF22 can be made on the same plane), thereby achieving a significant reduction in the size of the coil outer diameter 50 and avoiding problems when attaching it to the cassettes 51A and 51B.

[0150] In the example above, the step B was described as being provided on one side of the coil 50 which is the short side. However, the step B may also be provided on one side of the coil 50 which is the long side. The position of the step B can be appropriately selected depending on the shape of the leads at the starting end SE and the ending end EE.

[0151] As described above, the present invention is not limited to the embodiments described, and can be configured in various forms. For example, the bent portion of the coil piece may be curved.

[0152] Furthermore, a single coil piece is not limited to one formed by punching out a single copper sheet, but may also be formed by arranging multiple thin rectangular conductors (for example, rectangular conductors with a square cross-section in the longitudinal direction of the band, as shown in Figure 16(e)) in parallel along the short-side of the coil. Alternatively, the coil may be formed in part by a coil piece made by punching out a single copper sheet, and in part by a coil piece formed by arranging thin rectangular conductors in parallel. [Industrial applicability]

[0153] This invention can be used, for example, when manufacturing a coil device using a rectangular coil. [Explanation of symbols]

[0154] 10 Cold welding apparatus 20 Coil manufacturing equipment 11 1st holding part 12 Second holding part 50 coils

Claims

1. The process involves preparing a helical structure in which each region of one full turn of the spiral includes a bent portion, A step of deforming the helical structure so as to compress it in the axial direction of the helix, The process of forming the helical structure in the axial direction of the helix to match the shape of the stator, The process involves covering each of the surrounding regions with insulating resin after the molding, Having, A coil manufacturing method characterized by the following features.

2. Each of the aforementioned regions is formed in a roughly rectangular shape. The coil manufacturing method according to feature 1.

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