Stator and method for manufacturing stator

Abstract

A stator (100) according to an embodiment of the present invention comprises: a stator core (110) in which a plurality of stator slots are formed; a plurality of coil segments (130) each having a straight section (131) formed from enamel-coated flat wire and accommodated respectively in two different stator slots (111) and a connecting section (132) connecting the two straight sections (131) on the outer side of a first axial end (110a) of the stator core (110); and a stator winding (120) provided with, for respective phases, a plurality of linking sections (125) that connect the plurality of coil segments (130) in series on the outer side of a second axial end (110b) of the stator core (110). An insulating section (131j) is formed on the outer surface of the enamel coating on the surface of a portion of the straight sections (131) in the plurality of coil segments (130), said portion excluding accommodated portions (131h) to be accommodated in the stator slots (111).

Description

Stator and method for manufacturing the same

[0001] The present invention relates to a stator and a method for manufacturing a stator.

[0002] In electric motors and generators used in EVs (electric vehicles), PEVs (plug-in electric vehicles), and the like, a large current flows through the stator winding, and therefore a rectangular wire (rectangular conductor) with a large cross-sectional area is used as the conductor of the stator winding. Therefore, since the connection unit including the rectangular wire becomes large and causes interference with peripheral components of the motor, a technology is desired that enables the connection unit to be housed compactly near the motor.

[0003] In view of this situation, a method is known for conventional rotating electric machines in which enamel-coated rectangular wire (enameled wire) is arranged in multiple layers axially outward of the coil ends of the stator winding to make the wiring unit more compact.

[0004] Patent No. 6610249

[0005] In a stator wound with distributed windings using rectangular wire, there are places at the coil ends where the enameled wires come into contact with each other. Even if the wires are of the same phase within the stator slot, the enameled wires of different phases will come into contact at the coil ends.

[0006] If the enamel coating of the enameled wire is made thicker to prevent contact at the coil ends, the coating inside the slots will also become thicker, which means that the cross-sectional area of ​​the conductor inside the slots needs to be reduced accordingly, which increases the resistance and leads to problems such as increased copper loss and motor loss.

[0007] An object of the present invention is to provide a stator and a method of manufacturing the stator that can improve the insulation of the stator winding at the coil ends without thickening the coating of the enameled wire in the slots.

[0008] In order to achieve the above-mentioned object, a stator according to an embodiment of the present invention comprises: a cylindrical stator core having a plurality of stator slots formed circumferentially on its inner surface; and a stator winding comprising, for each phase, a plurality of coil segments made of enamel-coated rectangular wire, each having a straight portion that is accommodated in two different stator slots and a connecting portion that connects the two straight portions outside a first axial end of the stator core, and a plurality of jumper portions that connect the plurality of coil segments in series outside a second axial end of the stator core, wherein an insulating portion is formed on the outer surface of the enamel coating on the surface of the plurality of coil segments excluding the portions of the straight portions that are accommodated in the stator slots.

[0009] FIG. 1 is a longitudinal cross-sectional view including the central axis of rotation showing the configuration of a rotating electric machine having a stator according to an embodiment. FIG. 2 is a partial cross-sectional view perpendicular to the central axis of rotation showing the configuration of the stator according to an embodiment. FIG. 3 is a plan view showing coil segments that constitute the stator winding of the stator according to an embodiment. FIG. 4 is a flow chart showing the steps of a method for manufacturing a stator according to an embodiment. FIG. 5 is a plan view showing a first type coil segment used in assembling the stator winding of the stator according to an embodiment. FIG. 6 is a longitudinal cross-sectional view showing a foamed adhesive sheet as an insulating coating member that forms an insulating portion in the coil segments of the stator according to an embodiment. FIG. 7 is a plan view showing a second type coil segment used in assembling the stator winding of the stator according to an embodiment. FIG. 8 is a conceptual development view explaining the connection of coil segments that constitute the stator winding of the stator according to an embodiment.

[0010] Hereinafter, a stator and a method of manufacturing a stator according to an embodiment of the present invention will be described with reference to the drawings. Here, identical or similar parts are denoted by common reference numerals, and duplicated explanations will be omitted.

[0011] FIG. 1 is a vertical cross-sectional view including a central axis of rotation showing the configuration of a rotating electric machine having a stator according to an embodiment.

[0012] The rotating electric machine 1 includes a rotor 10 , a stator 100 , a bearing 21 , a bearing bracket 22 , and a frame 23 .

[0013] The rotor 10 has a rotor shaft 11 rotatably supported by two bearings 21, a rotor core 12 attached to the radially outer side of the rotor shaft 11, and a permanent magnet 13 housed in the rotor core 12. Note that although a permanent magnet type rotor is shown as an example in Fig. 1, other types of rotors may also be used, such as a rotor for an induction type rotating electric machine or a wound rotor.

[0014] The stator 100 has a cylindrical stator core 110 and a stator winding 120 wound around the stator core 110 .

[0015] Here, with respect to the stator winding 120, the portion outside the first end 110a of the stator core 110 will be referred to as a first coil end 120a, and the portion outside the second end 110b will be referred to as a second coil end 120b.

[0016] Each phase of the stator winding 120 is made up of a plurality of coil segments 130 connected in series. Each coil segment 130 has two straight portions 131 and a connecting portion 132 connecting the two straight portions 131.

[0017] The coil segment 130 is an enamel-coated rectangular wire, and an insulating portion 131j (FIG. 3) is formed on a part of its surface. The insulating portion 131j will be described in detail later with reference to FIG.

[0018] FIG. 2 is a partial cross-sectional view perpendicular to the central axis of rotation showing the configuration of the stator 100 according to the embodiment.

[0019] A plurality of stator slots 111 are formed at intervals in the circumferential direction on the inner peripheral surface of the stator core 110 of the stator 100. Adjacent stator slots 111 each form a stator tooth 112.

[0020] Each stator slot 111 houses a straight portion 131 of a coil segment 130. Fig. 2 shows an example in which six layers, namely, a first layer conductor 131a, a second layer conductor 131b, a third layer conductor 131c, a fourth layer conductor 131d, a fifth layer conductor 131e, and a sixth layer conductor 131f, are stacked in each stator slot 111 from the radially outer side to the radially inner side. The following description will be given taking the case of six layers as an example, but the number of layers is not limited to six.

[0021] FIG. 3 is a plan view showing the coil segments 130 that constitute the stator winding 120 of the stator 100 according to the embodiment.

[0022] Each coil segment 130 has an insulating portion 131j on the surface of the enameled wire in the straight portion 131 except for the accommodated portion 131h, which is the portion of the straight portion 131 that is accommodated in the stator slot 111. More specifically, the insulating portion 131j is provided on a part of the straight portion 131 and the connecting portion 132 that constitutes the first coil end 120a, which is the outer portion of the first end 110a, and on a part of the straight portion 131 and the crossover portion 125 that constitutes the second coil end 120b, which is the outer portion of the second end 110b.

[0023] The insulating portion 131j is formed using, for example, a foam adhesive sheet, insulating varnish, powder coating, insulating tape, foam adhesive material, or the like.

[0024] FIG. 4 is a flowchart showing the steps of a method for manufacturing the stator 100 according to the embodiment.

[0025] First, the first type coil segment and the second type coil segment 130 are fabricated by attaching an insulating material to each coil segment (step S01).

[0026] FIG. 5 is a plan view showing a first type coil segment 130a used in assembling the stator winding 120 of the stator 100 according to this embodiment.

[0027] An insulating coating member 140 is attached to the first type coil segment 130a except for the accommodated portion 131h and the groove 123. In detail, the insulating coating member 140 is attached to a part of the straight portion 131a and the range of the connecting portion 132a that constitutes the first coil end 120a, and to a range of the straight portion 131a that constitutes the second coil end 120b except for the groove 123.

[0028] 6 is a longitudinal cross-sectional view showing a foam adhesive sheet 141 as an insulating covering member 140 that forms the insulating portion 131j of a coil segment of a stator according to this embodiment. As described above, examples of the insulating covering member 140 that can be used include a foam adhesive sheet, insulating varnish, powder coating, insulating tape, and a foam adhesive. The following description will be given using the foam adhesive sheet 141 as an example of the insulating covering member 140.

[0029] The foam adhesive sheet 141 has a planar substrate 141a and foam adhesive layers 141b applied to both sides of the substrate 141a. The substrate 141a is, for example, a film made primarily of polymeric materials. The foam adhesive layer 141b foams and becomes adhesive when heated. The insulating portion 131j shown in FIG. 3 becomes foamed and adhesive when the foam adhesive sheet 141 becomes hot during the stator assembly process.

[0030] FIG. 7 is a plan view showing a second type coil segment 130b used in assembling the stator winding 120 of the stator 100 according to this embodiment.

[0031] An insulating coating member 140 is attached to the first type coil segment 130a except for the accommodated portion 131h and the groove 123. More specifically, the insulating coating member 140 is attached to a part of the straight portion 131a and the range of the connecting portion 132a that constitutes the first coil end 120a.

[0032] In the flow diagram of Figure 4, next, it is determined whether or not the first-type coil segment 130a can be inserted into the stator slot 111 to be inserted (step S02). That is, it is confirmed whether or not there is enough room in each stator slot 111 to allow the first-type coil segment 130a to pass through. The reason for this is as follows. When determining whether or not there is enough room, the number of straight portions 131 already present in the stator slot 111 may be used as a guide, such as whether or not the number is less than four.

[0033] In order to prevent the radial dimension of the stator slot 111 from increasing compared to the conventional dimension, as shown in Fig. 3, the portion of the straight portion 131 that is housed in the stator slot 111 is left enameled without forming an insulating portion 131j. For this reason, conversely, for example, if multiple layers of straight portions already exist in the stator slot 111, when inserting the first-type coil segment 130a into this stator slot 111, there is a risk that the tip portion on which the insulating portion 131j is formed will not be able to pass through the stator slot 111. In other words, if there is not enough room in the stator slot 111 to allow the first-type coil segment 130a to pass through, it is necessary to pass the second-type coil segment 130b, which does not have the insulating portion 131j formed at its tip portion, through it.

[0034] If it is determined that the first type coil segment 130a can be inserted into the stator slot 111 to be inserted (step S02 YES), that is, if there is sufficient space for the number of straight portions 131 already stored in each of the two slots, for example, four or less, then the first type coil segment 130a is used as the coil segment 130 for insertion.

[0035] On the other hand, if it is not determined that the first-type coil segment 130a can be inserted into the insertion target stator slot 111 (step S02 NO), i.e., if, for example, five straight portions 131 are already housed in one of the two slots, the second-type coil segment 130b is used as the coil segment 130 for insertion (step S04). This is because, as described above, if an attempt is made to insert all six first-type coil segments 130a, the presence of the insulating coating member 140 on the surface may prevent the straight portions 131a from passing through the stator slot 111. Following step S04, the insulating coating member 140 is attached to the straight portions 131b protruding from the stator core 110 (step S05).

[0036] After steps S03 and S05, the coil segments 130 are connected to each other, and then other components such as connections to the outside and neutral points are attached (step S07).

[0037] 8 is a conceptual development view illustrating the connection of the coil segments 130 that constitute the stator winding 120 of the stator 100 according to the embodiment, that is, a diagram illustrating the contents of step S05.

[0038] In step S05, an insulating coating member 140 is attached to the straight portion 131b protruding from the stator core 110, and then this portion is bent circumferentially to form a bent portion 131x. A groove 123 is formed at the tip of the bent portion 131x, which allows welding or brazing to the groove 123 at the tip of the bent portion of another coil segment 130. By connecting this portion by welding or brazing, a jumper portion 125 is formed. An insulating coating member 140 is also attached to the jumper portion 125.

[0039] Finally, the insulating covering members 140 attached to the respective portions of the stator winding 120 become the insulating portions 131j, for example, by heating or temperature increase.

[0040] According to the embodiment described above, it is possible to provide a stator and a method for manufacturing a stator that can improve the insulation of the stator winding at the coil ends without thickening the coating of the enameled wire in the slots. Furthermore, by using, for example, foam adhesive sheet 141 as insulating coating member 140, it is possible to stably fix the coil ends and ensure reliable vibration resistance.

[0041] [Other Embodiments] Although the embodiments of the present invention have been described above, they are presented as examples and are not intended to limit the scope of the invention. Furthermore, features of each embodiment may be combined. Furthermore, the embodiments may be implemented in various other forms, and various omissions, substitutions, and modifications may be made without departing from the spirit of the invention. The embodiments and their modifications are intended to be included within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as set forth in the claims.

[0042] DESCRIPTION OF SYMBOLS 1... rotating electric machine, 10... rotor, 11... rotor shaft, 12... rotor core, 13... permanent magnet, 21... bearing, 22... bearing bracket, 23... frame, 100... stator, 110... stator core, 110a... first end, 110b... second end, 111... stator slot, 112... stator tooth, 120... stator winding, 120a... first coil end, 120b... second coil end, 121... flat rectangular conductor, 123... groove, 125... jumper portion, 130... core coil segment, 130a...A-type coil segment, 130b...B-type coil segment, 131...straight portion, 131a...first layer conductor, 131b...second layer conductor, 131c...third layer conductor, 131d...fourth layer conductor, 131e...fifth layer conductor, 131f...sixth layer conductor, 131h...housed portion, 131j...insulating portion, 131x...folded portion, 132...connecting portion, 140...insulating coating member, 141...foamed adhesive sheet, 141a...base material, 141b...foamed adhesive portion

Claims

1. A stator comprising: a stator core having a cylindrical shape with a plurality of stator slots formed in the circumferential direction on the inner peripheral surface; a plurality of coil segments each having a straight portion made of an enamel-coated rectangular wire, the straight portions being respectively accommodated in two different stator slots, and a connecting portion connecting the two straight portions outside the first end portion of the stator core in the axial direction; and a stator winding including a plurality of bridging portions that connect the plurality of coil segments in series outside the second end portion in the axial direction, wherein in the plurality of coil segments, an insulating portion is formed on the outer surface of the enamel coating in a portion of the straight portion excluding the portion accommodated in the stator slot.

2. The stator according to claim 1, wherein at least one of a foamed adhesive sheet, insulating varnish, powder coating, insulating tape, and foamed adhesive is used for the insulating portion.

3. A method for manufacturing a stator, comprising: manufacturing a first type of coil segment having an insulating coating for forming an insulating portion on the surfaces of the straight portion side and the connecting portion side excluding the portion accommodated in the stator slot of the straight portion, and a second type of coil segment having the insulating coating only on the surface of the connecting portion side excluding the portion accommodated in the stator slot of the straight portion, for a coil segment made of an enamel-coated rectangular wire and having two straight portions and a connecting portion connecting the two straight portions; determining whether the first type of coil segment can be inserted into the slot to be inserted; inserting the first type of coil segment when it is determined that the first type of coil segment can be inserted; inserting the second type of coil segment and applying the insulating coating on the surface of the portion of the straight portion protruding from the stator slot when it is determined that the first type of coil segment cannot be inserted; and connecting the coil segments to each other.

4. The method for manufacturing a stator according to claim 3, wherein the step of connecting the coil segments to each other includes, first, a step of bending a portion of the straight portion of the coil segment arranged outside the accommodated portion along the circumferential direction.

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