Foamed adhesive flat wire, stator, and stator manufacturing method

Abstract

According to an embodiment, a foamed adhesive flat wire (10) is provided with: a flat conductor (11) having a substantially rectangular cross section; an enamel layer (12) provided on the outer surface of the flat conductor (11); and a foamed adhesive layer (13) provided on the outer surface of the enamel layer (12) and capable of foaming and bonding at a predetermined temperature or higher. When the foamed adhesive layer (13) is not adjacent to another member at each side surface of the foamed adhesive flat wire (10), the thickness of the foamed adhesive layer side surface (13c, 13d) may be reduced or zero as compared with a case in which the foamed adhesive layer (13) is adjacent to another member.

Description

Foamed adhesive rectangular wire, stator, and stator manufacturing method

[0001] The present invention relates to a foam-bonded rectangular wire, a stator, and a method for manufacturing a stator.

[0002] In the stators of rotating electrical machines, rectangular conductors with a nearly rectangular cross section are often used for the stator windings. The outer surface of the rectangular conductor is usually coated with an enamel layer.

[0003] When windings are made using rectangular conductors, it is necessary to ensure vibration resistance, that is, to prevent fluctuations in the relative positions of the rectangular conductors or between the rectangular conductors and the stator core.

[0004] For this reason, it is necessary to fix the stator winding with varnish.

[0005] JP 2022-34889 A

[0006] When fixing the stator winding with varnish, there was a difference in the penetration and adhesion of the varnish between the stator winding in the slot and the stator winding at the coil end, which could reduce reliability.In addition, the management of conditions in the varnish process and the time required for the varnish process reduced manufacturability.

[0007] An object of the present invention is to provide a foamed adhesive rectangular wire, a stator, and a method for manufacturing a stator that can stably fix windings and increase reliability in terms of vibration resistance.

[0008] In order to achieve the above-mentioned object, a foamed adhesive flat wire according to an embodiment of the present invention is characterized by comprising: a flat conductor having an approximately rectangular cross section; an enamel layer provided on the outer surface of the flat conductor; and a foamed adhesive layer provided on the outer surface of the enamel layer, which is foamable and adhesive at a predetermined temperature or above.

[0009] 1 is a partial cross-sectional view showing a foamed adhesive rectangular wire according to the first embodiment. FIG. 2 is a partial cross-sectional view showing the stator winding of the stator according to the first embodiment. FIG. 3 is a partial cross-sectional view showing the B-B section of FIG. 2 showing the stator winding of the stator according to the first embodiment. FIG. 4 is a partial cross-sectional view showing the CC section and the D-D section of FIG. 2 showing the stator winding of the stator according to the first embodiment. FIG. 5 is a partial cross-sectional view showing a foamed adhesive rectangular wire according to the second embodiment. FIG. 6 is a partial longitudinal section showing a heat-foamed sheet for a foamed adhesive rectangular wire according to the second embodiment. FIG. 7 is a perspective view illustrating a method for connecting rectangular wires inside a stator in a stator manufacturing method according to a third embodiment. FIG. 8 is a longitudinal cross-sectional view showing a groove in the method for connecting rectangular wires inside a stator in a stator manufacturing method according to the third embodiment. FIG. 9 is a flow chart showing the steps of the stator manufacturing method according to the third embodiment.

[0010] Hereinafter, a foam-bonded rectangular wire, a stator, and a method for manufacturing a stator according to an embodiment of the present invention will be described with reference to the drawings. Hereinafter, identical or similar parts will be designated by common reference numerals, and redundant description will be omitted.

[0011] First Embodiment FIG. 1 is a partial cross-sectional view showing a foamed adhesive rectangular wire 10 according to a first embodiment.

[0012] The foamed adhesive flat wire 10 has a flat conductor 11 having a rectangular cross section and extending in the longitudinal direction, an enamel layer 12 provided on the outer periphery of the flat conductor, and a foamed adhesive layer 13 provided on the outer periphery of the enamel layer 12.

[0013] Here, the corners 11c of the rectangular conductor 11, i.e., the ridges, in other words the four corners in the cross-sectional view of Fig. 1, may be tapered or rounded, but the overall shape may be substantially rectangular. Hereinafter, the cross-sectional shape will be referred to as rectangular, including the case where the cross-sectional shape is substantially rectangular with such corners 11c.

[0014] The enamel layer 12 is formed to a substantially uniform thickness on all four sides of the foamed adhesive rectangular wire, where "substantially uniform" means that the thickness is within the range of application variations and the accuracy of measurements when checking.

[0015] The foamed adhesive layer 13 foams and exhibits its adhesive function when heated or when its temperature is raised above a predetermined temperature. In the case of a thermoplastic resin, the predetermined temperature may be the glass transition temperature. In FIG. 1 , the foamed adhesive layer 13 is shown formed to a substantially uniform thickness on all four sides. However, as described below, the thickness of each side may vary depending on the conditions of the application location. Hereinafter, for the sake of convenience, the upper portion of the side on which the foamed adhesive layer 13 is applied will be referred to as the foamed adhesive layer upper surface 13a, the lower portion as the foamed adhesive layer lower surface 13b, and the lateral portions as the foamed adhesive layer side surfaces 13c and 13d.

[0016] 2 is a perspective view showing a portion of the stator winding 24 of the stator 20 according to the first embodiment. The stator 20 is disposed radially outside the rotor (not shown) so as to surround the rotor. The stator 20 has a stator core 21 and a stator winding 24.

[0017] For ease of explanation, in the following description, the upward direction in FIG. 2 will be referred to as the radially outward direction, the lateral direction as the circumferential direction, and the direction perpendicular to the radial and circumferential directions as the axial direction.

[0018] Stator teeth 23 are formed at intervals in the circumferential direction (one revolution) on the stator core 21. Stator slots 22 are formed by the stator teeth 23 that are adjacent to each other in the circumferential direction.

[0019] As part of the stator winding 24, a first coil segment 25 a and a second coil segment 25 b are shown inserted into the stator slots 22. Here, each of the coil segments, such as the first coil segment 25 a and the second coil segment 25 b, has two straight portions 25 c extending in the axial direction and a connecting portion connecting the two straight portions 25 c. Each straight portion 25 c is inserted into a stator slot 22. The two straight portions 25 c of the same coil segment are inserted into different stator slots 22.

[0020] Figure 2 shows a case in which one straight portion 25c of the first coil segment 25a and most of one straight portion 25c of the second coil segment 25b are housed in the same stator slot 22 and are adjacent to each other vertically.

[0021] 1 shown above shows the shape of the cross section A-A in FIG. 2. The A-A cross section is the location where the straight portions 25c of the first coil segment 25a and the second coil segment 25b are housed in the stator slot 22. Here, the first coil segment 25a and the second coil segment 25b are adjacent to each other, and the first coil segment 25a and the second coil segment 25b are adjacent to the slot inner wall 22a (FIG. 2). In other words, this is the location where four side surfaces of each of the first coil segment 25a and the second coil segment 25b are adjacent to other conductor portions.

[0022] In such a location, the thicknesses of the two sides of the foamed adhesive layer 13 of the foamed adhesive rectangular wire 10, i.e., the foamed adhesive layer upper surface 13a, the foamed adhesive layer lower surface 13b, and the foamed adhesive layer side surfaces 13c and 13d, are substantially uniform, or may be varied depending on the potential difference between the adjacent objects.

[0023] FIG. 3 is a partial cross-sectional view showing the stator winding 24 of the stator according to the first embodiment, taken along line BB of FIG.

[0024] 2, the first coil segment 25a and the second coil segment 25b are adjacent to each other, but there is no adjacent object on the side of each of the first coil segment 25a and the second coil segment 25b. That is, in the first coil segment 25a and the second coil segment 25b, the only adjacent objects are the foamed adhesive layer upper surface 13a and the foamed adhesive layer lower surface 13b. If the coil segment is not at the outermost or innermost position in the radial direction, only the foamed adhesive layer upper surface 13a and the foamed adhesive layer lower surface 13b are adjacent.

[0025] In this way, in areas where there are no adjacent objects on the side surfaces of the first coil segment 25 a and the second coil segment 25 b, the foamed adhesive layer 13 does not need to foam and expand to adhere to the adjacent objects. Therefore, in such cases, as shown in Fig. 3, the thickness of the foamed adhesive layer 13 on the foamed adhesive layer side surfaces 13 c and 13 d may be smaller than the thickness of the foamed adhesive layer 13 on the foamed adhesive layer upper surface 13 a and the foamed adhesive layer lower surface 13 b. Alternatively, the foamed adhesive layers 13 may be formed partially, for example, spaced apart from each other in the longitudinal direction, or may not be formed at all.

[0026] FIG. 4 is a partial cross-sectional view showing the stator winding 24 of the stator according to the first embodiment, taken along lines CC and DD in FIG.

[0027] The CC and DD cross sections in Figure 2 show locations where there are no adjacent objects on any side of the first coil segment 25a and the second coil segment 25b, respectively. In locations where there are no adjacent objects, the foamed adhesive layer 13 does not need to foam and expand to adhere to the adjacent objects. Therefore, in such cases, as shown in Figure 4, the thickness of the foamed adhesive layer 13 on the foamed adhesive layer upper surface 13a, the foamed adhesive layer lower surface 13b, and the foamed adhesive layer side surfaces 13c and 13d may be smaller than the thickness in the first embodiment. Alternatively, the foamed adhesive layer 13 may be partially formed in the longitudinal direction, or may not be formed at all.

[0028] In each portion of the stator 20, the foamed adhesive layer 13 is heated, causing the foamed adhesive layer 13 to foam and expand in volume. Furthermore, when the foamed foamed adhesive layer 13 comes into contact with an adjacent member, the foamed adhesive rectangular wire 10 can be bonded to that member. As a result, the stator winding 24 can be stably fixed.

[0029] 5 is a partial cross-sectional view of a foamed adhesive rectangular wire 10a according to a second embodiment. This embodiment is a modification of the first embodiment, in which a heat-foamable sheet 14 is wound around the surface of the enamel layer 12 as the foamed adhesive layer 13.

[0030] FIG. 6 is a partial vertical cross-sectional view showing a heat-foamable sheet 14 of a foamed adhesive rectangular wire 10a according to the second embodiment.

[0031] The heat-foamable sheet 14 comprises a film substrate 14a, an adhesive layer 14b formed on the surface of the film substrate 14a, a nonwoven fabric layer 14c provided on the outer surface of the adhesive layer 14b, and a foamable adhesive layer 14d formed on the outer surface of the nonwoven fabric layer 14c. The foamable adhesive layer 14d foams when heated to a predetermined temperature or higher. In this case, the predetermined temperature is, for example, the glass transition temperature of a thermoplastic resin, such as about 100°C to 120°C.

[0032] The film substrate 14a may be a resin film made of polyester resin, polyamide resin, polyimide resin, polysulfone resin, polyether ketone resin, or the like.

[0033] The adhesive layer 14b bonds the nonwoven fabric layer 14c to the film substrate 14a, and the material thereof may be, for example, a thermoplastic resin-based, thermosetting resin-based, or elastomer-based adhesive.

[0034] The nonwoven fabric layer 14c may be a nonwoven fabric made of fibers such as cellulose fibers, polyester fibers, nylon fibers, aramid fibers, polyphenylene sulfide fibers, liquid crystal polymer fibers, glass fibers, metal fibers, and carbon fibers.

[0035] The foamable adhesive layer 14d contains an epoxy resin, a curing agent, a thermoplastic resin, and a foaming agent, and may also contain other additives such as a curing accelerator and a filler, if necessary.

[0036] The foamed adhesive flat wire 10a of this embodiment configured as described above is easy to assemble by wrapping the heat-foamed sheet 14 as the foamed adhesive layer 13 on the surface of the enamel layer 12, and can achieve the same effects as in the first embodiment.

[0037] [Third embodiment] Fig. 7 is a perspective view illustrating a flat wire stator internal connection method in a stator manufacturing method according to a third embodiment. Also, Fig. 8 is a vertical cross-sectional view showing a groove in the flat wire stator internal connection method in a stator manufacturing method according to a third embodiment.

[0038] This embodiment is a modification of the first embodiment. Typically, a coil segment having two straight portions and a connecting portion connecting them is inserted from one end of the stator core 21 and connected at the other end. However, this embodiment relates to a connection method in which the coil segments are inserted from both sides of the stator core 21 and the straight portions are connected within the stator slots 22 (FIG. 8).

[0039] Specifically, as shown in Figure 7, a first flat wire 17a, which is the straight portion of the coil segment inserted from the first end 21a of the stator core 21, and a second flat wire 17b, which is the straight portion of the coil segment inserted from the second end 21b of the stator core 21, are butted together at their respective tips in the groove portion 18 within the same stator slot 22.

[0040] As shown in Figure 8, a tapered first groove 18a is formed at the tip of the first rectangular wire 17a. A tapered second groove 18b is formed at the tip of the second rectangular wire 17b. In the groove portion 18, the tapered surfaces of the first groove 18a and the second groove 18b are in close contact with each other. This state corresponds to the next step S03 of contacting the groove portions.

[0041] FIG. 9 is a flowchart showing the procedure of the stator manufacturing method according to the third embodiment.

[0042] First, the stator core 21 is assembled (step S01).

[0043] Next, each coil segment with a groove formed therein is prepared (Step S02). Specifically, first, grooves are formed at the tip of the straight portion of the rectangular conductor 11 of each coil segment (Step S02a). Next, each coil segment is formed (Step S02b). That is, a coil segment having two straight portions and a connecting portion is produced.

[0044] The step S01 of assembling the stator core 21 and the step S02 of preparing each coil segment may be performed in parallel or in the reverse order, regardless of the order.

[0045] Next, step S03 of setting the coil segments is performed.

[0046] First, the straight portions of the coil segments are inserted into the stator slots 22 from both axial sides (step S03a). Specifically, the first coil segment 26a is inserted into the first stator slot 22 and the second stator slot from the first end 21a side of the stator core 21 to a predetermined axial depth. The second coil segment 26b is inserted into the first stator slot 22 and the second stator slot from the second end 21b side of the stator core 21 to a predetermined axial depth. Here, Figures 7 and 8 show a case where the first flat wire 17a of the straight portion of the first coil segment 26a and the second flat wire 17b of the straight portion of the second coil segment 26b are housed in the same first stator slot 22.

[0047] In step S03, all the coil segments may be inserted at the same time, or they may be inserted layer by layer.

[0048] Next, the adhesion between the grooves is confirmed and the coil segments are fixed (step S03b). Here, checking the adhesion is not essential. Even if checking is performed, it is difficult to check the adhesion of all grooves 18. Therefore, it is sufficient to observe the straight portion at the innermost circumference of the stator slot 22 from the inner periphery of the stator core 21. Alternatively, a random inspection may be performed to check only a predetermined number of grooves. Furthermore, if it is possible to determine in advance that the first groove 18a and the second groove 18b at the tips of the first and second rectangular wires 17a and 17b are in close contact when the first and second rectangular wires 17a and 17b are inserted to a predetermined depth, it may be possible to simply confirm that the grooves are at the predetermined depth. Furthermore, fixing the coil segments may be performed as needed.

[0049] Next, it is determined whether step S03 has been performed for all coil segments (step S04). If it is determined that step S03 has not been performed for all coil segments (step S04: NO), steps S03 and S04 are repeated.

[0050] As shown in Figure 8, the tapers of the first groove 18a and the second groove 18b are formed with the same inclination, so when the first flat wire 17a and the second flat wire 17b are inserted and their tips are in contact with each other, the first groove 18a and the second groove 18b are in close contact with each other. The outer enamel layer 12 and the foam adhesive layer 13 of each flat conductor 11 are also formed with the same inclination, so they are in close contact with each other. Here, "in close contact" means that the processing accuracy of the inclination of the tapers of the first flat wire 17a and the second flat wire 17b and the relative positioning accuracy of the first flat wire 17a and the second flat wire 17b are within the range.

[0051] If it is determined that step S03 is to be performed for all the coil segments (YES in step S04), the foam adhesive rectangular wire 10 or 10a is then adhesively fixed (step S05).

[0052] Specifically, first, an external terminal (not shown) is connected to a power source (step S05a). This connection may include temporary wiring. Next, current is applied to the rectangular conductors 11 (step S05b). This current application is continued for a predetermined time. This predetermined time is the time required for welding the rectangular conductors 11 together and for the foamed adhesive layer 13 to cover the rectangular conductors 11 in the grooves 18. Finally, the adhesion of the foamed adhesive layers 13 to each other is confirmed (step S05c). Since it is difficult to check all grooves 18, the straight line portion at the innermost periphery of the stator core 21 within the stator slot 22 may be observed. Alternatively, a sampling inspection may be performed on only a predetermined number of rectangular conductors.

[0053] In this manner, the stator 20 including the stator core 21 and the stator winding 24 is assembled and manufactured.

[0054] According to this embodiment, the windings can be stably fixed even when a method is used in which the coil segments are inserted from both sides of the stator core 21 and their respective straight portions are connected within the stator slots 22.

[0055] According to the embodiments described above, it is possible to provide a foamed adhesive rectangular wire, a stator, and a method for manufacturing a stator that stably fixes windings and increases reliability in terms of vibration resistance.

[0056] [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.

[0057] 10, 10a...Foamed adhesive flat wire, 11...Flat conductor, 11c...Corner portion, 12...Enamel layer, 13...Foamed adhesive layer, 13a...Upper surface of foamed adhesive layer, 13b...Lower surface of foamed adhesive layer, 13c, 13d...Side surface of foamed adhesive layer, 14...Heat-foamed sheet, 14a...Film substrate, 14b...Adhesive layer, 14c...Nonwoven fabric layer, 14d...Foamed adhesive layer, 17a...First flat wire, 17b...Second flat wire, 18...Groove portion, 18a...first groove, 18b...second groove, 20...stator, 21...stator core, 21a...first end, 21b...second end, 22...stator slot, 22a...slot inner wall, 23...stator teeth, 24...stator winding, 25a...first coil segment, 25b...second coil segment, 25c...straight portion, 26a...first coil segment, 26b...second coil segment

Claims

1. A foamed adhesive rectangular wire comprising: a rectangular conductor having a substantially rectangular cross section; an enamel layer provided on the outer surface of the rectangular conductor; and a foamed adhesive layer provided on the outer surface of the enamel layer, the foamed adhesive layer being foamable and adhesive at or above a predetermined temperature.

2. A foamed adhesive rectangular wire as described in claim 1, characterized in that when the foamed adhesive layer is not adjacent to another component on each side of the foamed adhesive rectangular wire, the thickness of the foamed adhesive layer on that side is reduced or zero compared to when it is adjacent to another component.

3. The foamed adhesive rectangular wire according to claim 1, characterized in that the foamed adhesive layer is a heat-foamable sheet, the heat-foamable sheet having a film substrate or a nonwoven fabric substrate, and a foamable adhesive layer formed on the surface of the film substrate or the nonwoven fabric substrate.

4. The foamed adhesive rectangular wire according to claim 1, characterized in that the foamed adhesive layer is a heat-foamable sheet having a film substrate, an adhesive layer formed on the surface of the film substrate, a nonwoven fabric layer provided on the outer surface of the adhesive layer, and a foamable adhesive layer formed on the outer surface of the nonwoven fabric layer.

5. A foamed adhesive rectangular wire as described in claim 1, characterized in that, on the four sides of the rectangular conductor on which the foamed adhesive layer is formed, the foamed adhesive layer is present only on two opposing sides out of the four sides.

6. A foamed adhesive rectangular wire as described in claim 1, characterized in that on each side of the rectangular conductor on which the foamed adhesive layer is formed, the foamed adhesive layer is partially formed in areas spaced apart from each other in the longitudinal direction of the rectangular conductor.

7. A stator comprising: a stator core having a number of stator slots formed on the inner circumference at intervals in the circumferential direction; and a stator winding made of the foamed adhesive rectangular wire according to any one of claims 1 to 6, a part of which is housed within the stator slot.

8. A stator comprising a stator core having a number of stator slots formed on its inner periphery at intervals in the circumferential direction, and a stator winding using the foamed adhesive rectangular wire according to claim 6, the two side faces with the foamed adhesive layer being the circumferential faces of the stator slot in which a portion of the stator winding is housed.

9. The stator of claim 8 further comprising slot insulation paper within said stator slots.

10. A stator manufacturing method comprising the steps of: assembling a stator core having a plurality of stator slots; preparing each coil segment having a groove formed therein; inserting a first coil segment from a first end side of the stator core into a first stator slot and a second stator slot to a predetermined depth in the axial direction; inserting a second coil segment from a second end side of the stator core into the first stator slot and a second stator slot to a predetermined depth in the axial direction; and adhesively fixing a foamed adhesive rectangular wire by heating a rectangular conductor, wherein the predetermined depth is a depth at which the groove of the first coil segment and the groove of the second coil segment are in close contact in the first stator slot.

11. A method for manufacturing a stator according to claim 10, characterized in that the heating is performed by passing an electric current through the foamed adhesive rectangular wire to generate heat.

Images