Coil Twisting Device

Abstract

To prevent a segment coil from being twisted in a twisting step of bending a protruding portion of the segment coil while making it fall in a circumferential direction, so as to prevent a welding defect from occurring in a subsequent welding step.SOLUTION: In a twisting step of bending a protruding portion 23, which protrudes from a stator core 10 toward one side in an axial direction, while making it fall in a circumferential direction in a plurality of segment coils 20 which is inserted into slots 11 of the stator core 10 and disposed side by side in a radial direction and of which the cross section is formed rectangular, the protruding portion 23 is bent in a state where the protruding portion 23 of the plurality of segment coils 20 is pressed in the radial direction.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a stator of a rotating electrical machine and a coil twisting device.

Background Art

[0002] As a stator of a rotating electrical machine, one using a large number of U-shaped segment coils is known (see, for example, Patent Document 1 below). This type of stator is manufactured through an insertion process of inserting a large number of segment coils into slots provided in a stator core, an expansion process of widening the radial interval of protruding portions protruding from each slot to one axial side among the segment coils, a twisting process of bending the protruding portions of the segment coils to one circumferential side or the other, and a welding process of welding the ends of the segment coils together.

[0003] Among the above processes, in the twisting process, as shown in FIG. 13, among the segment coils 103, the protruding portion 104 protruding from the slot 102 of the stator core 101 is bent while being tilted in the circumferential direction (see the dotted line). Specifically, the tip of the protruding portion 104 of the segment coil 103 is grasped by a twisting jig (not shown), and while rotating this twisting jig to one circumferential side or the other and approaching the stator core 101, the protruding portion 104 is tilted to one circumferential side or the other while the protruding portion 104 is bent. In the illustrated example, a cuff 105 is arranged on the end face of the stator core 101, and a bent portion 106 is formed in the protruding portion 104 of the segment coil 103 starting from the contact portion with this cuff 105.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the twisting process as described above, in order to arrange the end portions of each segment coil 103 in proximity to the end portions of other segment coils 103 to be welded thereto, it is necessary to tilt the protruding portion 104 of the segment coil 103 along a direction L2 (see FIG. 14) inclined with respect to the tangential direction L1, rather than tilting it along the tangential direction L1. For this reason, a torsional moment as indicated by the arrow in FIG. 14 is applied near the base end portion of the protruding portion 104 of the segment coil 103 (near the contact portion with the cuff 105). Since a slight gap is provided between the stator core 101 and the segment coil 103 to enable the segment coil 103 to be inserted into the slot 102 of the stator core 101, when the torsional moment as described above is applied, the segment coil 103 may be twisted. When the segment coil 103 is twisted in this way, the positional accuracy of the tip of the segment coil 103 deteriorates, so that in the subsequent welding process, the end portions of the segment coils 103 to be welded cannot be brought sufficiently close to each other, which may cause welding defects.

[0006] Therefore, an object of the present invention is to prevent twisting of a segment coil and prevent welding defects in a subsequent welding process in a twisting process of bending the protruding portion of the segment coil while tilting it in the circumferential direction.

Means for Solving the Problems

[0007] The present invention made to solve the above problems is in a twisting process of bending a protruding portion protruding from one axial side of a stator core while tilting it in the circumferential direction, among a plurality of segment coils having a rectangular cross section inserted into slots of the stator core and arranged side by side in the radial direction of the stator core, characterized in that the protruding portions of the plurality of segment coils are bent in a state where the protruding portions are pressed from the radial direction.

[0008] Thus, by pressing the protruding portions of the plurality of segment coils from the radial direction, the side surfaces of the protruding portions of the segment coils having a rectangular cross section press against each other, so that the torsion of each protruding portion is restricted. In this state, even when a torsional moment is applied near the base end portion of the protruding portion by bending the protruding portion of the segment coil while tilting it in the circumferential direction, it is possible to prevent the segment coil from twisting.

[0009] Of the plurality of segment coils arranged side by side in the radial direction, the protruding portion of the segment coil arranged on the outer diameter side is longer than the protruding portion of the segment coil arranged on the inner diameter side (see FIG. 4). Therefore, when the protruding portion of the segment coil is bent in the twisting process, the torsional moment applied near the base end portion of the protruding portion of the segment coil on the outer diameter side becomes larger than the torsional moment applied near the base end portion of the protruding portion of the segment coil on the inner diameter side. Therefore, it is preferable to press the protruding portions of the plurality of segment coils from the outer diameter side of the stator core. Thereby, since a radial pressing force is likely to be applied to the protruding portion of the segment coil on the outer diameter side where twisting is likely to occur, twisting of the segment coil can be effectively prevented.

[0010] In the above twisting process, it is preferable to press the base end portion side (stator core side) in the radial direction as much as possible among the protruding portions of the plurality of segment coils arranged side by side in the radial direction. For example, when a cuff is provided on one axial side of the stator core in contact with the protruding portion to form a bending starting point, it is preferable to press the portion arranged in the axial region of the cuff from the radial direction among the protruding portions of the plurality of segment coils.

[0011] The above manufacturing method includes a twisting jig that is inserted into each slot of the stator core and bends the protruding portion protruding axially from one side of the stator core in the circumferential direction while tilting the protruding portion of the plurality of segment coils having a rectangular cross section arranged side by side in the radial direction of the stator core, and can be realized by using a coil twisting device having a pressing jig that presses the protruding portions of the plurality of segment coils from the radial direction.

Advantages of the Invention

[0012] As described above, according to the present invention, in the twisting process of bending while tilting the protruding portion of the segment coil in the circumferential direction, it is possible to prevent the twisting in the vicinity of the base end portion of the protruding portion. As a result, the accuracy of the position of the end portion of the segment coil is improved, so that it is possible to prevent welding defects in the subsequent welding process.

Brief Description of the Drawings

[0013]

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Embodiments for Carrying Out the Invention

[0014] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0015] The stator of the rotating electrical machine (motor) of the present embodiment is manufactured through (1) a coil insertion process, (2) an expansion process, (3) a twisting process, and (4) a welding process. In this specification, the axial direction, the circumferential direction, and the radial direction respectively mean the axial direction, the circumferential direction, and the radial direction of the stator core 10.

[0016] (1) Coil Insertion Process In the coil insertion process, as shown in FIGS. 1 and 2, a plurality of segment coils 20 are inserted into a plurality of slots 11 provided in the stator core 10. The stator core 10 is formed in a substantially cylindrical shape as a whole, for example, by laminating a plurality of annular electromagnetic steel sheets, or by firing a compacted body of magnetic powder. The stator core 10 has a cylindrical portion 12 and a plurality of teeth 13 protruding radially inward from a plurality of circumferentially equally spaced positions of the cylindrical portion 12, and slots 11 are provided between the circumferential directions of adjacent teeth 13. At the inner diameter end of the teeth 13, protruding portions 13a protruding on both circumferential sides are provided. The circumferential width of the inner diameter end of the slot 11 (between the protruding portions 13a of the teeth 13) is smaller than the circumferential width of the segment coil 20, and the circumferential width of the slot 11 in other regions (regions on the outer diameter side of the protruding portion 13a) is slightly larger than the circumferential width of the segment coil 20. Thereby, the segment coil 20 can be inserted into the slot 11, and the plurality of segment coils 20 inserted into each slot 11 are held from the inner diameter side by the protruding portions 13a of the teeth 13, and the escape from the slot 11 to the inner diameter side is restricted.

[0017] As shown in Fig. 3, the segment coil 20 is a flat wire having a rectangular cross section (a cross section perpendicular to the extending direction of the segment coil 20), and is composed of a conductor wire 20a and an insulating film 20b covering the periphery thereof. The conductor wire 20a is formed of, for example, copper, and the insulating film 20b is formed of, for example, enamel. The segment coil 20 has a U shape composed of a pair of linear leg portions 21 and a connecting portion 22 connecting the ends of the pair of leg portions 21. The ends of the segment coil 20, that is, the free ends 21a of the pair of leg portions 21 (the ends on the side opposite to the connecting portion 22), have the insulating film 20b peeled off and the conductor wire 20a exposed.

[0018] The pair of leg portions 21 of each segment coil 20 are respectively inserted into different slots 11. In each slot 11, the leg portions 21 of a plurality of segment coils 20 are arranged side by side in the radial direction. In the present embodiment, eight leg portions 21 are inserted into each slot 11 (see Fig. 1). As shown in Fig. 2, the region including the end portions 21a (the portions where the conductor wire 20a is exposed) of the leg portions 21 of each segment coil 20 protrudes axially from the slot 11 of the stator core 10 to one side in the axial direction (upward in the figure). Hereinafter, among the leg portions 21 of each segment coil 20, the portion protruding axially from the slot 11 of the stator core 10 to one side in the axial direction (the end portion 21a side) is referred to as a "protruding portion 23".

[0019] (2) Expansion process In the expansion process, a gap is formed by pushing an expansion blade (not shown) from above between the protruding portions 23 in the radial direction of a plurality of segment coils 20 arranged side by side in the radial direction. In the present embodiment, as shown in Fig. 4, the expansion blade is pushed between the second and third protruding portions 23, the fourth and fifth protruding portions 23, and the sixth and seventh protruding portions 23 from the inner diameter side, and radial gaps G1 to G3 are respectively formed therebetween.

[0020] (3) Twisting process In the twisting process, the protruding portions 23 of each segment coil 20 are bent while being tilted to one side or the other side in the circumferential direction. Referring to FIG. 1 for explanation, among the protruding portions 23 of each slot 11, the odd-numbered protruding portions 23 counted from the inner diameter side are tilted to one side in the circumferential direction (see arrow B1), and the even-numbered protruding portions 23 counted from the inner diameter side are tilted to the other side in the circumferential direction (see arrow B2). That is, the protruding portions 23 of the segment coils 20 adjacent in the radial direction are tilted in the opposite circumferential directions.

[0021] As shown in FIG. 5, the coil twisting device used in the twisting process has a plurality of twisting jigs 31 arranged on one axial side (upper side in the figure) of the stator core 10 and a base 32 arranged on the other axial side (lower side in the figure) of the stator core 10.

[0022] The plurality of twisting jigs 31 each have a cylindrical shape coaxial with the stator core 10 and are arranged in a state of overlapping each other in the radial direction. The number of twisting jigs 31 provided is the same as the number of leg portions 21 of the segment coil 20 inserted into one slot 11 (eight in this embodiment). Each twisting jig 31 has the same diameter as the cylinder connecting the leg portions 21 of the segment coil 20 arranged at the same radial position within each slot 11. That is, the twisting jig 31 with the smallest diameter has the same diameter as the cylinder connecting the innermost leg portions 21 within each slot 11, and the twisting jig 31 adjacent to its outer diameter side has the same diameter as the cylinder connecting the second leg portions 21 from the inner diameter side within each slot 11 (the same applies to the other twisting jigs 31). The twisting jig 31 is provided with a holding portion for holding the end portion 21a of the segment coil 20. In this embodiment, a plurality of recesses 31a equal in number to the slots 11 are provided at the end portion on the other axial side (lower side in the figure) of the twisting jig 31, and these recesses 31a function as the holding portion. The twisting jig 31 is rotatable around the axis of the stator core 10 and is also capable of approaching and separating from the stator core 10 (reciprocating movement in the axial direction).

[0023] The base 32 abuts against the connecting portion 22 of the segment coil 20 that protrudes axially to the other side from the slot 11 of the stator core 10 from the other axial side (lower side in the figure). Thereby, the movement of the segment coil 20 axially to the other side with respect to the stator core 10 is restricted.

[0024] In this embodiment, a cuff 33 is provided on one axial side of the stator core 10. The cuff 33 is arranged, for example, in contact with the end face on one axial side of the stator core 10. The cuff 33 has a plurality of bending starting portions 33a equal in number to the slots 11. Each bending starting portion 33a has a columnar shape extending in the radial direction and is arranged between the circumferential directions of the protruding portions 23 of the segment coils 20 protruding axially from the slots 11 to one side. The cuff 33 of this embodiment is a jig used only in the twisting process, and the bending starting portion 33a can be inserted and removed from the outer diameter side between the circumferential directions of the protruding portions 23 of the segment coils 20. After the twisting process, the cuff 33 is removed from the stator core 10.

[0025] The above coil twisting device is provided with a pressing jig 34 which is a characteristic configuration of the present invention. The pressing jig 34 is arranged on the outer diameter side of the protruding portion 23 of the segment coil 20 protruding axially from each slot 11 to one side. The pressing jigs 34 are provided in the same number as the slots 11 and are reciprocated in the radial direction by driving means (not shown) respectively.

[0026] In the twisting process, first, the stator core 10 with the segment coils 20 inserted is set in the coil twisting device. Specifically, as shown in FIG. 5, the end portions 21a of the respective segment coils 20 are fitted into the concave portions 31a of the twisting jig 31, and the connecting portions 22 of the respective segment coils 20 are supported from the other axial side by the base 32.

[0027] Thereafter, as shown by arrow D in FIG. 6, by moving the pressing jig 34 inward in the inner diameter direction, the protruding portions 23 of the plurality of segment coils 20 arranged side by side in the radial direction are pressed from the outer diameter side. As shown in FIG. 7, the plurality of segment coils 20 inserted into each slot 11 are held from the inner diameter side by the protruding portions 13a provided at the inner diameter ends of the teeth 13 of the stator core 10. Thus, the plurality of segment coils 20 inserted into each slot 11 are pressed from both sides in the radial direction by the pressing jig 34 and the protruding portions 13a of the teeth 13. That is, among the plurality of segment coils 20, the protruding portions 23 protruding from the slots 11 are pressed from the outer diameter side by the pressing jig 34, and the portions arranged in the slots 11 are pressed from the inner diameter side by the protruding portions 13a of the teeth 13.

[0028] In this state where the protruding portions 23 of the plurality of segment coils 20 protruding from each slot 11 are pressed from the outer diameter side by the pressing jig 34, the twisting jig 31 is driven to bend the protruding portions 23. Specifically, the odd-numbered twisting jigs 31 from the inner diameter side are rotated in one circumferential direction around the central axis of the stator core 10 (see arrow C1 in FIG. 8), and the twisting jigs 31 are moved closer to the stator core 10 (see arrow C2 in FIG. 8). Along with this, the protruding portions 23 of the segment coils 20 whose end portions 21a are held by the twisting jigs 31 are tilted in one circumferential direction, and a bent portion Q starting from the contact portion with the bending starting portion 33a of the cuff 33 is formed near the base end portion of the protruding portion 23 (see FIG. 9). At the same time, the even-numbered twisting jigs 31 from the inner diameter side are rotated in the other circumferential direction and moved closer to the stator core 10, whereby the protruding portions 23 of the segment coils 20 whose end portions 21a are held by the twisting jigs 31 are tilted in the other circumferential direction, and a bent portion starting from the contact portion with the bending starting portion 33a of the cuff 33 is formed near the base end portion of the protruding portion 23 (not shown).

[0029] At this time, the segment coil 20 is pushed axially toward the other side (the lower side in the figure) by the twisting jig 31 (see arrow C2 in Fig. 8). However, since the connecting portion 22 of the segment coil 20 is supported from the other side in the axial direction by the base 32 (see Fig. 5), axial displacement of the segment coil 20 with respect to the stator core 10 is prevented.

[0030] By the way, in order to arrange the end portion 21a of each segment coil 20 close to the end portion 21a of another segment coil 20 to be welded thereto, the protruding portion 23 of the segment coil 20 is not tilted along the tangential direction, but is tilted along a direction L2 (see Fig. 14) inclined with respect to the tangential direction L1, and the free end 21a and the base end portion (near the contact portion with the cuff 33) of the protruding portion 23 need to be arranged on substantially the same circumference. For this reason, a torsional moment that attempts to rotate the protruding portion 23 of each segment coil 20 around its own axis acts near the base end portion of the protruding portion 23 of each segment coil 20 (see the arrow in Fig. 14). In particular, the protruding portion 23 of the segment coil 20 provided on the outer diameter side of each slot 11 is longer than the protruding portion 23 of the segment coil 20 provided on the inner diameter side and is displaced to the outer diameter side by the expansion process (see Fig. 4), so the torsional moment applied near the base end portion becomes larger. In the present embodiment, as shown in Fig. 6, the protruding portions 23 of a plurality of segment coils 20 arranged side by side in the radial direction are pressed from the radial direction by the pressing jig 34, so that the side surfaces of the protruding portions 23 of the segment coil 20 having a rectangular cross section are pressed against each other in the radial direction, and thus the twisting of each protruding portion 23 due to the above-mentioned torsional moment is restricted.

[0031] At this time, the protruding portion 23 of the segment coil 20 is pressed from the outer diameter side by the pressing jig 34, but is not directly pressed from the inner diameter side. The portion below the protruding portion 23 (the portion arranged in the slot 11) is held from the inner diameter side by the protruding portion 13a of the teeth 13 (see Fig. 7). In this case, since the protruding portions 23 of the plurality of segment coils 20 escape to the inner diameter side and are slightly bent by the pressing force of the pressing jig 34, the pressing force of the pressing jig 34 is particularly difficult to be transmitted to the protruding portion 23 arranged on the inner diameter side. As described above, since the protruding portion 23 arranged on the outer diameter side is long and is displaced to the outer diameter side by the expansion process, the torsional moment applied in the twisting process is larger than that of the protruding portion 23 arranged on the inner diameter side. Therefore, by pressing the protruding portions 23 of the plurality of segment coils 20 from the outer diameter side with the pressing jig 34 as described above, the pressing force of the pressing jig 34 is more likely to be transmitted to the protruding portion 23 arranged on the outer diameter side to which a relatively large torsional moment is applied, so that the twisting of the segment coil 20 can be effectively prevented.

[0032] In the above twisting process, it is preferable to press, with the pressing jig 34, the base end portion side (the region close to the stator core 10) as much as possible among the protruding portions 23 of the plurality of segment coils 20 arranged in each slot 11. In the present embodiment, among the protruding portions 23 of the plurality of segment coils 20, the portion arranged in the axial direction region of the cuff 33 is pressed with the pressing jig 34. In the illustrated example, the entire pressing region by the pressing jig 34 among the protruding portions 23 is arranged within the axial direction region of the cuff 33. Note that the present invention is not limited to this, and the pressing region by the pressing jig 34 may protrude from the axial direction region of the cuff 33 to one side in the axial direction (the upper side in the figure).

[0033] After the protruding portions 23 of the plurality of segment coils 20 are bent as described above, the bending starting point portion 33a of the cuff 33 is retracted to the outer diameter side, and the cuff 33 is removed from the stator core 10. As a result, as shown in Fig. 10, the end portion 21a of the protruding portion 23 of the segment coil 20 twisted to one side in the circumferential direction and the end portion 21a of the protruding portion 23 of the other segment coil 20 twisted to the other side in the circumferential direction are arranged at positions adjacent in the radial direction.

[0034] (4) Welding process In the welding process, the ends 21a of the segment coils 20 adjacent in the radial direction are welded by arc welding (for example, Tig welding). As a result, a U-phase coil, a V-phase coil, and a W-phase coil each composed of a plurality of electrically connected segment coils 20 are formed.

[0035] The present invention is not limited to the above-described embodiment. Hereinafter, other embodiments of the present invention will be described, but redundant descriptions of the same points as those in the above-described embodiment will be omitted.

[0036] In the above embodiment, the case where the protruding portions 23 of the plurality of segment coils 20 protruding from each slot 11 are pressed by the pressing jig 34 only from the outer diameter side is shown. However, the present invention is not limited to this, and the protruding portions 23 of the plurality of segment coils 20 arranged side by side in the radial direction may be pressed from both the outer diameter side and the inner diameter side. For example, as shown in FIG. 11, pressing jigs 34 and 35 that can approach and separate in the radial direction are provided on the outer diameter side and the inner diameter side of the protruding portions 23 of the plurality of segment coils 20 arranged in each slot 11, and the protruding portions 23 of the plurality of segment coils 20 are clamped and pressurized from both sides in the radial direction by these pressing jigs 34 and 35. Thereby, the twisting of the segment coil 20 can be more reliably prevented. In this case, it is preferable that both pressing jigs 34 and 35 are arranged to face each other in the radial direction. Further, both pressing jigs 34 and 35 may be movable in the radial direction, or one pressing jig (for example, the pressing jig 34 on the outer diameter side) may be movable in the radial direction, and the other pressing jig (for example, the pressing jig 35 on the inner diameter side) may be fixed in the radial direction.

[0037] Further, the protruding portions 23 of the plurality of segment coils 20 arranged in each slot 11 may be pressed by a pressing jig only from the inner diameter side. In this case, a pressing jig movable in the radial direction is provided on the inner diameter side of the protruding portions 23 of the plurality of segment coils 20 arranged side by side in the radial direction.

[0038] In the above embodiment, the case where the cuff 33 is removed from the stator core 10 after the twisting process is shown. However, the present invention is not limited to this, and the subsequent process may be performed with the cuff 33 attached to the stator core 10. In this case, as shown in FIG. 12, for example, the cuff 33 can integrally include a plurality of bending starting portions 33a, a small-diameter ring portion 33b that connects the inner diameter ends of the plurality of bending starting portions 33a, and a large-diameter ring portion 33c that connects the outer diameter ends of the plurality of bending starting portions 33a.

Description of Reference Numerals

[0039] 10 Stator core 11 Slot 12 Cylindrical portion 13 Teeth 20 Segment coil 21 Leg portion 22 Connecting portion 23 Protruding portion 31 Twisting jig 32 Base 33 Cuff 34 Pressing jig

Claims

**Claim 1** Among a plurality of segment coils having a rectangular cross section that are inserted into respective slots of a stator core and arranged side by side in the radial direction of the stator core, a twisting jig that bends while tilting in the circumferential direction a protruding portion that protrudes axially from one side of the stator core; A coil twisting device having a pressing jig that presses the protruding portions of the plurality of segment coils from the radial direction.

Images