stata

Abstract

This technology provides a way to suppress the overheating of the middle section of a slot. [Solution] The stator comprises a stator core and coils attached to the stator core. The stator core has a slot that penetrates the stator core in the axial direction and accommodates a portion of the coils. The slot comprises a first section including one end in the axial direction of the slot, a second section including the other end in the axial direction of the slot, and an intermediate section located between the first and second sections. In the first and second sections, a fixing member is filled between the outer surface of the coil and the inner surface of the slot. In the intermediate section, no fixing member is filled between the outer surface of the coil and the inner surface of the slot. The stator core has a flow path that connects the intermediate section to the outside of the stator core.

Description

Technical Field

[0001] The technology disclosed in this specification relates to the stator of an electric motor.

Background Art

[0002] The stator disclosed in Patent Document 1 includes a stator core that extends cylindrically along the axial direction of the stator, and a rectangular wire (coil) housed in the slots of the stator core. Between the inner surface of the slot and the rectangular wire, insulating paper provided with a plurality of recesses extending along the axial direction is disposed. A cooling medium for cooling the rectangular wire flows through the recesses of the insulating paper.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When power is supplied to the rectangular wire, the rectangular wire generates heat. The slots of the stator core of Patent Document 1 are open at both axial ends. Therefore, at both ends of the slot, the heat of the rectangular wire is easily released to the outside of the stator core. However, in the above-described stator, the rectangular wire is arranged in the rectangular slot without a gap, and the heat in the intermediate section in the axial direction of the slot may stay without being released to the outside of the stator core. In this case, the intermediate section of the slot may become high temperature. This specification provides a technique for suppressing the intermediate section of the slot from becoming high temperature.

Means for Solving the Problems

[0005] The technology disclosed herein is embodied in a stator for an electric motor. The stator comprises a stator core and coils mounted on the stator core. The stator core has a slot that penetrates the stator core in the axial direction and accommodates a portion of the coils. The slot comprises a first section including one end of the slot in the axial direction, a second section including the other end of the slot in the axial direction, and an intermediate section located between the first and second sections. In the first and second sections, a fixing member is filled between the outer surface of the coils and the inner surface of the slot. In the intermediate section, the fixing member is not filled between the outer surface of the coils and the inner surface of the slot. The stator core has a flow path connecting the intermediate section to the outside of the stator core.

[0006] In the above configuration, no fixing member is filled between the outer surface of the coil and the inner surface of the slot in the intermediate section. Therefore, a space exists between the outer surface of the coil and the inner surface of the slot in the intermediate section. Furthermore, since the intermediate section is connected to the outside of the stator core by the flow path, heat accumulated in the intermediate section can be released to the outside of the stator core through the flow path. Therefore, it is possible to suppress the intermediate section of the slot from becoming too hot. [Brief explanation of the drawing]

[0007] [Figure 1] A partial cross-sectional view of an electric motor 10 equipped with a stator 20 according to an embodiment. [Figure 2] Cross-sectional view along line II-II in Figure 1. [Modes for carrying out the invention]

[0008] In one embodiment of this technology, the coil may include a first coil segment protruding from one end of the slot, a second coil segment protruding from the other end of the slot, and a connecting member that electrically connects the first coil segment and the second coil segment. In this case, the connecting member may be located in the intermediate section of the slot.

[0009] Around the connecting member that electrically connects the first coil segment and the second coil segment, the electrical resistance is higher than in the general parts of each coil segment. As a result, heat generation increases around the connecting member, and it tends to become hot. With this configuration, since the connecting member is located in the intermediate section, the heat around the connecting member can be released to the outside of the stator core through the flow path.

[0010] In one embodiment of this technology, the connecting member may be composed of a tubular material that accommodates the end of the first coil segment and the end of the second coil segment.

[0011] With this configuration, each coil segment can be electrically connected using a relatively simple structure, provided that the ends of each coil segment are housed in tubular material.

[0012] In one embodiment of this technology, the stator is disposed within the slot and may further include insulating paper extending from the first section through the intermediate section to the second section. In this case, the fixing member may be composed of foamed resin coated on the insulating paper in the first and second sections. Furthermore, the foamed resin may not be coated on the insulating paper in the intermediate section.

[0013] With this configuration, for example, by applying foamed resin to the portions corresponding to the first and second sections of a single insulating paper, and not applying foamed resin to the portion corresponding to the intermediate section, the intermediate section without a fixed member can be formed relatively easily.

[0014] In one embodiment of this technology, the stator core may comprise a plurality of slots, each slot arranged along the circumferential direction of the stator core, and a plurality of flow channels, each flow channel provided for a corresponding one of the plurality of slots. In this case, each of the plurality of flow channels may comprise a main channel section extending axially along the stator core and a branch channel section branching off from the main channel section and connecting to the intermediate section of the slot. Furthermore, each of the main channel sections of the plurality of flow channels may be adjacent to the corresponding one of the plurality of slots from the radially outside of the stator core, and each of the branch channel sections of the plurality of flow channels may be in communication with the corresponding intermediate section of the plurality of slots.

[0015] With this configuration, the entire slot is cooled by a main flow section extending axially parallel to the slot, and by connecting the intermediate section and the diversion section, heat from the intermediate section can be released to the outside of the stator core via the diversion section and the main flow section. Furthermore, because the main flow section is adjacent to the slot from the radial outside, the magnetic flux density generated in the stator core can be increased compared to, for example, a configuration in which the main flow section is adjacent to the slot in the circumferential direction of the stator core.

[0016] (Examples) Figure 1 shows a partial cross-sectional view of an electric motor 10 equipped with a stator 20 of this embodiment. The electric motor 10 is used, for example, as a prime mover to drive wheels in an electric vehicle. Electric vehicles include, for example, battery electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, and fuel cell electric vehicles. In the following, the direction along the central axis A1 of the electric motor 10 (i.e., the direction from the foreground to the background of the paper in Figure 1) may be referred to as the axial direction D1 (see Figure 2). Similarly, the direction from the central axis A1 of the electric motor 10 toward the outer circumference may be referred to as the radial direction D2, and the direction along the outer circumference of the electric motor 10 may be referred to as the circumferential direction D3. Figure 1 shows a partial cross-sectional view of the electric motor 10 in a cross section perpendicular to the axial direction D1. Furthermore, with respect to the radial direction D2, the direction toward the outer circumference (i.e., the direction of the arrow in the radial direction D2) may be referred to as the "outside" of the radial direction D2, and the opposite direction may be referred to as the "inside" of the radial direction D2.

[0017] As shown in Figure 1, the electric motor 10 includes a stator 20, a shaft 12, a rotor 14, and a coil 40. The shaft 12 extends along the central axis A1 and supports the rotor 14. The rotor 14 is located inside the stator 20 in the radial direction D2 and rotates around the shaft 12. The rotor 14 is made of a soft magnetic material. In this embodiment, the rotor 14 has a structure in which electromagnetic steel sheets are laminated. In addition, a plurality of permanent magnets 16 are arranged on the rotor 14 along the circumferential direction D3.

[0018] The stator 20 includes a stator core 22. The stator core 22 is constructed using a soft magnetic material. In this embodiment, the stator core 22 has a structure in which multiple electromagnetic steel sheets (not shown) are laminated. The stator core 22 extends cylindrically along the axial direction D1 described above. That is, the axial direction D1 coincides with the axial direction of the stator core 22. Multiple coil fixing parts 30 for attaching coils 40 to the stator core 22 are arranged at predetermined intervals along the circumferential direction D3. Each of the multiple coil fixing parts 30 has a similar configuration.

[0019] Referring to the enlarged view above FIG. 1 and FIG. 2, the details of the coil fixing portion 30 will be described. The coil fixing portion 30 includes a slot 32, an insulating paper 34, a foamed resin 36, and a flow path 50. As shown in FIG. 2, the slot 32 is a space that penetrates the stator core 22 in the above-described axial direction D1. The coil 40 passes through the slot 32 and extends along the axial direction D1. That is, the slot 32 houses a part of the coil 40.

[0020] The slot 32 extends along the axial direction D1 from the first end 31F to the second end 31S. The slot 32 includes a first section 32F including the first end 31F, a second section 32S including the second end 31S, and an intermediate section 32C located between the respective sections 32F and 32S.

[0021] Three-phase AC power is supplied to the coil 40 from an inverter (not shown) disposed outside the electric motor 10. Thereby, a magnetic force is generated between the stator 20 and the rotor 14, and the rotor 14 rotates. The coil 40 is composed of a plurality of coil wires C1 arranged along the radial direction D2. Each of the plurality of coil wires C1 includes a first coil segment 41 protruding from the first end 31F of the slot 32, a second coil segment 42 protruding from the second end 31S, and a pipe material 44 connecting the respective coil segments 41 and 42. In FIG. 2, only the coil wire C1 located on the innermost side in the radial direction D2 of the stator core 22 (that is, the right side of the paper surface of FIG. 2) is labeled, and the labels of the other coil wires C1 are omitted.

[0022] The pipe member 44 is a cylindrical member made of a conductive metal (e.g., copper). The pipe member 44 houses the first coil end 41E of the first coil segment 41 and the second coil end 42E of the second coil segment 42. As shown in FIG. 2, the respective coil ends 41E, 42E are not in contact with each other. However, the respective coil ends 41E, 42E are electrically connected via the pipe member 44. That is, the pipe member 44 is a connecting member that electrically connects the respective coil segments 41, 42. By electrically connecting the respective coil segments 41, 42 with the pipe member 44, the respective coil segments 41, 42 can be connected with a relatively simple configuration.

[0023] As shown in FIG. 2, the cross-sectional area of the first coil end 41E is smaller than the cross-sectional area of the other portions of the first coil segment 41. Similarly, the cross-sectional area of the second coil end 42E is smaller than the cross-sectional area of the other portions of the second coil segment 42. The pipe member 44 houses the respective coil ends 41E, 42E whose cross-sectional areas are reduced. Thereby, the outer diameter of the pipe member 44 can be reduced. For this reason, particularly with respect to the radial direction D2, the size of the slot 32 can be reduced, and the size of the electric motor 10 can be reduced.

[0024] Insulating paper 34 is disposed on the inner surface of the slot 32. The insulating paper 34 ensures insulation between the stator core 22 and each coil wire C1. In the present embodiment, the insulating paper 34 is composed of a single material having insulating performance extending from the first section 32F through the intermediate section 32C to the second section 32S. The insulating paper 34 is composed of, for example, a polyester film, an aramid film, a polyethylene terephthalate film, a polyethylene naphthalate film, or kraft paper.

[0025] The insulating paper 34 is coated with foamed resin 36. The foamed resin 36 is made of a foamable resin that expands when heated. The foamed resin 36 is formed on both sides of the insulating paper 34. In the manufacturing process of the stator 20, with the insulating paper 34 coated with foamed resin 36 placed on the inner surface of the slot 32 of the stator core 22, the first coil segment 41 of the coil wire C1 and the tubing material 44 are inserted into the slot 32 from the first end 31F of the slot 32, and then the second coil segment 42 is inserted into the slot 32 from the second end 31S. In this way, each coil segment 41 and 42 are connected via the tubing material 44. Subsequently, the stator core 22 and the coil wire C1 are heated, causing the foamed resin 36 to expand and fill the gap between the outer surface of the coil wire C1 and the inner surface of the slot 32, and the gap between each coil wire C1. In this way, the coil wire C1 of the coil 40 is fixed in the slot 32. In other words, the foamed resin 36 is a fixing member that secures the coil 40 to the slot 32.

[0026] As shown in Figure 2, in the first section 32F of the slot 32, foamed resin 36 is filled between the surface of the insulating paper 34 and the outer surface of the first coil segment 41 of the coil 40. Similarly, in the second section 32S, foamed resin 36 is filled between the surface of the insulating paper 34 and the outer surface of the second coil segment 42. However, in the intermediate section 32C, foamed resin 36 is not filled between the surface of the insulating paper 34 and the outer surfaces of each coil segment 41, 42. That is, in the intermediate section 32C, a space S1 is interposed between the inner surface of the slot 32 and the outer surfaces of each coil segment 41, 42.

[0027] In the manufacturing process of the stator 20, the following insulating paper 34 is used. In this insulating paper 34, the portion located in the intermediate section 32C is not coated with foamed resin. On the other hand, the portions located in the first section 32F and the second section 32S of the insulating paper 34 are coated with foamed resin. In this way, by not coating the portion located in the intermediate section 32C of a single sheet of insulating paper 34 with foamed resin, it is possible to easily form an intermediate section 32C that is not filled with foamed resin 36.

[0028] As mentioned earlier, the coil 40 is supplied with three-phase AC power from an inverter (not shown) to rotate the rotor 14. Because this three-phase AC power is high voltage, the coil 40 generates a relatively high amount of heat when it is supplied with this power. For this reason, a flow path 50 is provided in the stator 20.

[0029] The flow path 50 is adjacent to the slot 32 from the outside in the radial direction D2. The flow path 50 comprises a main channel section 52 that extends through the stator core 22 along the axial direction D1 of the stator core 22, and a branch channel section 54 that branches off from the main channel section 52 and extends inward in the radial direction D2. The flow path 50 is a space formed inside the stator core 22. Both ends of the main channel section 52 of the flow path 50 in the axial direction D1 are open to the outside of the stator core 22. The branch channel section 54 of the flow path 50 connects the main channel section 52 of the flow path 50 with the intermediate section 32C of the slot 32. That is, the flow path 50 connects the space S1 of the intermediate section 32C with the outside of the stator core 22.

[0030] Furthermore, the main channel section 52 of the flow path 50 is adjacent to the slot 32 from the outside in the radial direction D2. Therefore, compared to a configuration in which, for example, the main channel section 52 is adjacent to the slot 32 in the circumferential direction D3, the magnetic flux density generated when three-phase AC power is supplied to the coil 40 is less likely to be obstructed by the slot 32. As a result, the magnetic flux density generated in the stator core 22 increases, and the output of the electric motor 10 can be improved.

[0031] The flow path 50 is filled with oil L1. As shown by arrow F1 in Figure 2, the oil L1 flows into the main flow section 52 of the flow path 50 from the end adjacent to the first end 31F of the slot 32, passes through the space S1 of the intermediate section 32C, and flows out from the end adjacent to the second end 31S of the slot 32. In other words, the flow path 50 circulates the oil L1. The oil L1 is a cooling oil such as ATF (Automatic Transmission Fluid®). By circulating the oil L1 in the main flow section 52 of the flow path 50, which extends axially D1 parallel to each section 32F and 32S of the slot 32, each section 32F and 32S can be cooled. In addition, since oil L1 is supplied to the intermediate section 32C of the slot 32 via the diversion section 54 of the slot 32, the intermediate section 32C can also be cooled.

[0032] (Effects of this embodiment) In the stator 20 of this embodiment, since the foamed resin 36 is not filled in the intermediate section 32C of the slot 32, a space S1 is interposed between the outer surface of a part of each coil segment 41, 42 and the surface of the insulating paper 34. Furthermore, since the space S1 in the intermediate section 32C and the outside of the stator core 22 are connected by the flow path 50, the heat accumulated in the space S1 in the intermediate section 32C can be released to the outside of the stator core 22 via the flow path 50 and the oil L1 circulating through the flow path 50. As a result, it is possible to suppress the intermediate section 32C of the slot 32 from becoming too hot.

[0033] Furthermore, in the stator 20 of this embodiment, a pipe 44 connecting each coil segment 41, 42 is arranged in the intermediate section 32C. The electrical resistance is higher around the pipe 44 connecting each coil segment 41, 42 compared to the general portion of each coil segment 41, 42. Moreover, as mentioned earlier, the cross-sectional area of ​​the coil ends 41E, 42E of each coil segment 41, 42 is smaller than the cross-sectional area of ​​the general portion of each coil segment 41, 42. For this reason, the electrical resistance is higher at each coil end 41E, 42E, and the intermediate section 32C where the pipe 44 is arranged tends to become hotter. According to the stator 20 of this embodiment, the heat from the intermediate section 32C where the pipe 44 is arranged can be released to the outside of the stator core 22 via the flow path 50.

[0034] The specific examples of the technology disclosed herein have been described in detail above, but these are merely illustrative and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes to the specific examples illustrated above. Modifications of the above embodiments are listed below.

[0035] (Modification 1) The pipe material 44 does not have to be located in the intermediate section 32C of the slot 32. The pipe material 44 may be located, for example, in the first section 32F. In a further modification, the coil wire C1 of the coil 40 does not have to include the pipe material 44, and may be composed of a single coil segment.

[0036] (Modification 2) Each coil segment 41, 42 of the coil 40 does not have to be connected by the pipe material 44. Each coil segment 41, 42 may be connected to each other by welding, for example. In this modification, the welding member used to weld each coil segment 41, 42 is an example of a "connecting member".

[0037] (Modification 3) Each coil segment 41, 42 of the coil 40 does not have to be fixed to the slot 32 by the foamed resin 36. For example, each coil segment 41, 42 may be fixed to the slot 32 by varnish. In this modification, varnish is an example of a "fixing member".

[0038] (Modification 4) The main channel section 51 of the flow path 50 may be arranged adjacent to the slot 32 in the circumferential direction D3.

[0039] (Modification 5) In the embodiment described above, one flow path 50 is arranged for one slot 32. In this modification, for example, one flow path 50 may be connected to intermediate sections 32C of multiple slots 32. In that case, the flow path 50 may include one main channel section 51 and multiple branch sections 54 that branch off from the main channel section 51.

[0040] (Modification 6) Oil L1 does not necessarily have to circulate in the flow path 50. For example, air or other fluid may circulate in the flow path 50.

[0041] The technical elements described herein or in the drawings demonstrate technical usefulness individually or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Furthermore, the technologies illustrated herein or in the drawings can achieve multiple objectives simultaneously, and achieving even one of these objectives constitutes technical usefulness in itself. [Explanation of symbols]

[0042] 10: Electric motor, 12: Shaft, 14: Rotor, 16: Permanent magnet, 20: Stator, 22: Stator core, 30: Coil fixing section, 31F: First end, 31S: Second end, 32: Slot, 32C: Intermediate section, 32F: First section, 32S: Second section, 34: Insulating paper, 36: Foamed resin, 40: Coil, 41: First coil segment, 41E: First coil end, 42: Second coil segment, 42E: Second coil end, 44: Pipe material, 50: Flow path, 51: Main flow section, 52: Diverter section, A1: Central axis, C1: Coil wire, D1: Axial direction, D2: Radial direction, D3: Circumferential direction, L1: Oil, S1: Space

Claims

1. It is the stator of an electric motor, Stator core and The coil attached to the stator core, Equipped with, The stator core is provided with a slot that penetrates the stator core in the axial direction and accommodates a portion of the coil, The slot comprises a first section including one end of the slot in the axial direction, a second section including the other end of the slot in the axial direction, and an intermediate section located between the first section and the second section. In the first and second sections, a fixing member is filled between the outer surface of the coil and the inner surface of the slot. In the aforementioned intermediate section, the fixing member is not filled between the outer surface of the coil and the inner surface of the slot. The stator core is provided with a flow path that connects the intermediate section with the outside of the stator core. stata.

2. The aforementioned coil is A first coil segment protruding from one end of the slot, A second coil segment protruding from the other end of the slot, A connecting member that electrically connects the first coil segment and the second coil segment, Equipped with, The connecting member is positioned in the intermediate section of the slot. The stator according to claim 1.

3. The stator according to claim 2, wherein the connecting member is composed of a tubular material that accommodates the end of the first coil segment and the end of the second coil segment.

4. The insulating paper is further provided, which is arranged within the slot and extends from the first section through the intermediate section to the second section, In the first section and the second section, the fixing member is made of foamed resin applied to the insulating paper. In the aforementioned intermediate section, the foamed resin is not applied to the insulating paper. The stator according to claim 1.

5. The stator core is, A plurality of slots including the aforementioned slot, wherein the plurality of slots are arranged along the circumferential direction of the stator core, A plurality of channels including the channel, each of which is provided for one of the corresponding slots of the plurality, Each of the aforementioned multiple channels is, The stator core comprises a main channel section extending in the axial direction, A branch section that branches off from the main stream section and connects to the intermediate section of the slot, Equipped with, Each of the main flow sections of the plurality of flow paths is adjacent to the corresponding one of the plurality of slots from the radially outer side of the stator core. Each of the aforementioned multiple flow paths has a corresponding intermediate section of the aforementioned multiple slots, The stator according to claim 1.

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