stator

Abstract

The stator comprises: a stator core from which teeth protrude, an insulator covering the teeth, and a winding wound around the teeth via the insulator. The teeth have: a pair of short side surfaces adjacent to a pair of long side surfaces extending in a direction along the central axis of the stator core and extending in a direction intersecting the central axis; and a through-hole portion penetrating from one short side surface to the other short side surface. The insulator has: a pair of long side surface covering portions covering the pair of long side surfaces; a pair of short side surface covering portions covering the pair of short side surfaces; and a through-hole filling portion filling the through-hole portion. The long side surface covering portion includes an opening portion that exposes the long side surface and is open. A thermally conductive material having a higher thermal conductivity than the insulator is provided in the portion of the long side surface exposed from the opening portion.

Description

Technical Field

[0001] The present disclosure relates to a stator. Background Art

[0002] In electric motors, a stator is known that includes: a stator core having a plurality of teeth radially protruding from the inner circumference of a circular stator core and arranged circumferentially; an insulator covering the teeth; and windings wound around the teeth via the insulator. In electric motors that seek to be smaller and higher-output, it is a design challenge to facilitate heat transfer from the windings to the stator core and reduce the thermal resistance from the windings to the cooling water. To this end, Patent Document 1 discloses a stator in which the teeth of the stator core are covered by an insulator having a hole. The hole is filled with a highly thermally conductive insulating resin. The windings are wound over the insulator and the highly thermally conductive insulating resin.

[0003] Patent Document 1: Japanese Patent Application Laid-Open No. 2001-128402

[0004] However, in the above-mentioned technology, the high thermal conductivity insulating resin filled in the hole facilitates heat transfer from the winding to the stator core. However, the provision of the hole in the insulator reduces the rigidity of the insulator and the stator core. Summary of the Invention

[0005] To this end, the present disclosure describes a stator that can more easily transfer heat from a winding to a stator core and can ensure the rigidity of an insulator and a stator core.

[0006] One aspect of the present disclosure is a stator comprising: a stator core having a plurality of teeth projecting radially from an inner circumference of the annular stator core and arranged circumferentially; an insulator covering the teeth; and a winding wound around the teeth via the insulator, the teeth having: a pair of long side surfaces extending in a direction along a central axis of the stator core; a pair of short side surfaces adjacent to the long side surfaces and extending in a direction intersecting the central axis; and a through-hole portion penetrating from one short side surface to the other short side surface, the insulator having: a pair of long side surface covering portions respectively covering the pair of long side surfaces; a pair of short side surface covering portions respectively covering the pair of short side surfaces; and a through-hole filling portion filling the through-hole portion, the long side surface covering portions and the short side surface covering portions adjacent to each other being integrated with each other, the pair of short side surface covering portions being integrated with each other via the through-hole filling portion, the long side surface covering portions including an opening portion that exposes the long side surfaces and is open, and a thermally conductive material having a higher thermal conductivity than the insulator being provided at a portion of the long side surface exposed from the opening portion.

[0007] According to the stator of one aspect of the present disclosure, heat is more easily transferred from the winding to the stator core, and the rigidity of the insulator and the stator core can be ensured. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1This is a front view of the stator according to the embodiment, as seen from a direction along the central axis.

[0009] Figure 2 (A) is a side view of the stator according to the embodiment as viewed from the circumferential direction of the stator core. Figure 2 (B) is Figure 2 A cross-sectional view of line α of (A), Figure 2 (C) is Figure 2 Cross-sectional view taken along line β of (A).

[0010] Figure 3 yes Figure 2 Cross-sectional view taken along the γ line of (A).

[0011] Figure 4 (A) is a side view of a conventional stator as viewed from the circumferential direction of the stator core. Figure 4 (B) is Figure 4 The cross-sectional view at line δ of (A) is shown in FIG. Figure 4 (C) is Figure 4 Cross-sectional view at line ε of (A). DETAILED DESCRIPTION

[0012] One aspect of the present disclosure is a stator comprising: a stator core having a plurality of teeth projecting radially from an inner circumference of the annular stator core and arranged circumferentially; an insulator covering the teeth; and a winding wound around the teeth via the insulator, the teeth having: a pair of long side surfaces extending in a direction along a central axis of the stator core; a pair of short side surfaces adjacent to the long side surfaces and extending in a direction intersecting the central axis; and a through-hole portion penetrating from one short side surface to the other short side surface, the insulator having: a pair of long side surface covering portions respectively covering the pair of long side surfaces; a pair of short side surface covering portions respectively covering the pair of short side surfaces; and a through-hole filling portion filling the through-hole portion, the long side surface covering portions and the short side surface covering portions adjacent to each other being integrated with each other, the pair of short side surface covering portions being integrated with each other via the through-hole filling portion, the long side surface covering portions including an opening portion that exposes the long side surfaces and is open, and a thermally conductive material having a higher thermal conductivity than the insulator being provided at a portion of the long side surface exposed from the opening portion.

[0013] According to this structure, the stator comprises: a stator core having a plurality of teeth radially projecting from the inner circumference of the annular stator core and arranged circumferentially; an insulator covering the teeth; and windings wound around the teeth via the insulator. The teeth have a pair of long side surfaces extending along the central axis of the stator core; a pair of short side surfaces adjacent to the long side surfaces and extending in a direction intersecting the central axis; and a through-hole extending from one short side surface to the other short side surface.

[0014] The insulator comprises a pair of long side covering portions, each covering a pair of long side surfaces; a pair of short side covering portions, each covering a pair of short side surfaces; and a through-hole filling portion, which fills the through-hole portion. The long side covering portions include an opening portion that exposes the long side surfaces. A thermally conductive material having a higher thermal conductivity than the insulator is disposed in the portion of the long side surfaces exposed by the opening portion.

[0015] This facilitates heat transfer from the windings to the stator core. The long side covering portions include openings. However, adjacent long side covering portions and short side covering portions are integrated with each other, and a pair of short side covering portions are integrated with each other via a through-hole filling portion. This ensures the rigidity of the insulator and stator core.

[0016] In this case, it may also be that a pair of long side covering portions respectively include two opening portions, and the above-mentioned two opening portions are opened at the boundary between the pair of adjacent short side covering portions in such a manner that the short side covering portion and the long side face become the same plane when viewed from the direction along the center axis, and the pair of long side covering portions respectively cover the long side face between the two opening portions.

[0017] According to this structure, each pair of long side cover portions includes two openings, which open at the boundary between the adjacent pairs of short side cover portions so that the short side cover portions and the long side surfaces are flush with each other when viewed along the central axis. Therefore, undercuts are less likely to occur when insert-molding the insulator around the teeth of the stator core inserted into the mold, facilitating manufacturing. Furthermore, since the pair of long side cover portions each cover the long side surfaces between the two openings, the distance between the winding wound around the teeth via the insulator in the long side cover portions and the teeth is stable.

[0018] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. Figure 1 The electric motor of the stator 1 according to the present embodiment is used, for example, in a two-stage supercharging system in a supercharged engine for a 48V mild hybrid system, requiring both transient responsiveness and wide operating range. The electric motor of the stator 1 according to the present embodiment implements the electric compressor of the two-stage supercharging system and the electric assist turbine that regenerates excess turbine output during high-load conditions.

[0019] like Figure 1 、 Figure 2 (A) Figure 2 (B) Figure 2 (C) and Figure 3 As shown, the stator 1 includes a stator core 2, an insulator 4, and a winding 5. In the stator core 2, a plurality of teeth 3 protrude in the radial direction R of the inner circumference of the annular stator core 2 and are arranged along the circumferential direction C. The stator core 2 is divided into a plurality of core blocks along the circumferential direction C for each tooth 3. Figure 2 (A) Figure 2 (B) Figure 2 (C) and Figure 3 As shown, the stator core 2 is composed of a plurality of steel plates stacked in a direction along the central axis X of the stator core 2 .

[0020] The insulator 4 covers the teeth 3. The insulator 4 is a molded article made of synthetic resin. The insulator 4 is formed by insert molding, directly molding the insulator 4 onto the teeth 3 of the stator core 2. The winding 5 is wound around the teeth 3 via the insulator 4. The winding 5 is wound around each tooth 3 using concentrated winding. The winding 5 is made of a single copper wire with an extremely thick diameter of several millimeters to reduce copper loss.

[0021] The tooth 3 has a pair of long side surfaces 6 extending in a direction along the central axis X of the stator core 2. Furthermore, the tooth 3 has a pair of short side surfaces 7 that are adjacent to the long side surfaces 6 and extend in a direction intersecting the central axis X, in other words, in the circumferential direction C. The direction along the central axis X does not necessarily need to be parallel to the central axis X, as long as it is not perpendicular to the central axis X. Furthermore, the direction intersecting the central axis X does not necessarily need to be perpendicular to the central axis X, as long as it is not parallel to the central axis X. Furthermore, the directions in which the long side surfaces 6 and the short side surfaces 7 extend may differ across their entire surfaces or may vary depending on their positions.

[0022] The tooth 3 has a through hole portion 8 that penetrates from one short side surface 7 to the other short side surface 7. In this embodiment, in order to restore the magnetic circuit by an amount corresponding to the volume of the tooth 3 reduced by providing the through hole portion 8, the width of the tooth 3 in the circumferential direction C is made larger than Figure 4 (A) Figure 4 The teeth 30 of the conventional stator core 20 shown in FIG. 4(B) and FIG. 4(C) are wider than the width of the circumferential direction C of the through-hole portion 8. Figure 2 (B) and Figure 2 As shown in (C), the tooth 3 of this embodiment has a narrowing portion 16 near the end portion on the inner circumference side of the stator core 2, and the width of the narrowing portion 16 in the circumferential direction C decreases as it moves from the inner circumference side of the stator core 2 to the outer circumference side. In addition, the tooth 3 of this embodiment has an expanding portion 17, which is provided on the outer circumference side of the stator core 2 of the narrowing portion 16 and increases in the circumferential direction C as it moves from the inner circumference side of the stator core 2 to the outer circumference side. In other words, in the tooth 3 of this embodiment, a narrowing portion is formed near the end portion when viewed from the direction along the central axis X of the stator core 2. In addition, the through-hole portion 8 is formed at a position closer to the outer circumference side of the stator core 2 than the narrowing portion 16.

[0023] like Figure 2 (A) Figure 2 (B) Figure 2 (C) and Figure 3 As shown, the insulator 4 has a pair of long side covering portions 9 that respectively cover the pair of long side surfaces 6. Furthermore, the insulator 4 has a pair of short side covering portions 10 that respectively cover the pair of short side surfaces 7. Furthermore, the insulator 4 has a through-hole filling portion 11 that fills the through-hole portion 8. Furthermore, the insulator 4 has a base covering portion 12 that covers the base of the tooth 3, and a terminal covering portion 13 that covers the terminal portion of the tooth 3.

[0024] like Figure 2 As shown in (A), the adjacent long side cover 9 and short side cover 10 are integrated with each other via the base cover 12 and the terminal cover 13. Figure 3 As shown, a pair of short side covering parts 10 are integrated with each other via the through hole filling part 11. Figure 2 (A) Figure 2 (C) and Figure 3 As shown, the long side cover 9 includes an opening 14 that exposes the long side 6. Furthermore, the insulator 4 of this embodiment has six openings. Four of the six openings are openings 14 that expose the long side 6. One of the six openings is an opening in the terminal cover 13 that partially exposes the terminal end of the tooth 3. Assuming that the stator core 2 does not exist, the other of the six openings opens toward the outer periphery of the stator core 2 in the base cover 12, following the shape of the base of the tooth 3.

[0025] like Figure 3 As shown, each of the pair of long side covering portions 9 includes two openings 14, and the two openings 14 are opened at the boundary between the pair of adjacent short side covering portions 10 in such a manner that the short side covering portion 10 and the long side 6 become flush with the plane when viewed from the direction along the central axis X. Figure 2 (A) Figure 2 (B) and Figure 3 As shown, a pair of long side covering portions 9 covers the long side 6 between the two openings 14. The short side covering portion 10 has sufficient thickness to prevent the extremely thick winding 5, which is difficult to bend, from contacting the long side 6 exposed in the opening 14.

[0026] like Figure 2 (A) Figure 2 (C) and Figure 3 As shown, a thermally conductive material 15 having a higher thermal conductivity than the insulator 4 is provided on the portion of the long side 6 exposed from the opening 14. The thermally conductive material 15 is a paste-like thermally conductive compound such as silicone grease. By applying the paste-like thermally conductive compound to the opening 14, the thermally conductive material 15 is provided on the portion of the long side 6 exposed from the opening 14.

[0027] Typically, the thermal conductivity of the insulator 4 is approximately 0.3 to 0.5 W / mK. In contrast, the thermal conductivity of the thermally conductive material 15 is approximately 2 W / mK. When the winding 5 is wound around the teeth 3, the thermally conductive material 15 is compressed by the winding 5. Since the space between the winding 5 and the teeth 3 of the stator core 2 is filled with the thermally conductive material 15, heat is more easily transferred from the winding 5 to the stator core 2.

[0028] like Figure 2 (C) and Figure 3 As shown, the thermally conductive material 15 only needs to be filled between at least the first layer of the winding 5 wound in multiple layers and the teeth 3 of the stator core 2. Since the extremely thick winding 5 is difficult to bend, the first layer of the winding 5 wound in multiple layers does not necessarily follow the teeth 3 and insulator 4 throughout the entire circumference. Therefore, the thermally conductive material 15 needs to be filled between the first layer of the winding 5 wound in multiple layers and the teeth 3 of the stator core 2.

[0029] On the other hand, the second and subsequent layers of the multi-layered winding 5 are necessarily larger than the first layer because the winding radius of the winding 5 is always greater throughout the entire circumference. Therefore, the first layer of winding 5 is in close contact with the second and subsequent layers of winding 5. When the windings 5 are in contact with each other, heat is easily transferred between the windings 5. Therefore, the thermally conductive material 15 only needs to be filled between at least the first layer of the multi-layered winding 5 and the teeth 3 of the stator core 2.

[0030] In the above-mentioned use of the electric motor having the stator 1 involved in the present embodiment, since the size is required to be about the same as that of a conventional turbocharger and the output is about 4.5kW to 8kW, water cooling is basically applied. Since it processes a centrifugal compressor, the electric motor is ultra-high speed (a maximum of 80krpm in an electric compressor and a maximum of 200krpm in an electric auxiliary turbine), and a low inductance design is required to drive it at 48V. This means a reduction in the magnet torque, so the current value that must be processed to generate the above-mentioned output is a large value of about 150A at most. Therefore, the loss of the electric motor that should be dissipated is mainly copper loss. In order to realize an economical electric motor, the allowable temperature of the winding is limited to about 180°C, so reducing the thermal resistance from the winding to the cooling water becomes a design issue.

[0031] Typically, in such motors requiring small size and high output, after windings are wound around the stator core, a highly fluid casting resin, such as epoxy or silicone, is poured in to improve thermal conductivity and allowed to cure. This increases the contact area between the windings and the stator core, thereby reducing thermal resistance. However, this method requires a large amount (over 100g) of expensive casting resin and takes time to cure (approximately 30 to 60 minutes when heated). This, in turn, increases component costs.

[0032] As a simpler method, for example, as described in Patent Document 1 above, a proposal has been made to make a portion of the insulator covering the stator core from a highly thermally conductive insulating resin. Another proposal involves splitting the insulator in two along the central axis and replacing the long side with a thermally conductive sheet. However, these proposals all involve providing a hole in a portion of the insulator or separating the insulator from the stator core, which reduces the rigidity of the stator core and insulator.

[0033] like Figure 4 (A) Figure 4 (B) and Figure 4 As shown in (C), a method of insert-molding the insulator 40 directly onto the teeth 30 of the stator core 20 is proposed to improve the close contact between the insulator 40 and the stator core 20. In this method, the resin insert-molded insulator 40 increases the rigidity of the stator core 20, allowing the winding 5 to be wound around the teeth 30 with high tension. As a result, the winding 5 can use extremely thick single copper wire, capable of handling high currents and improving the reliability of the connection portion of the winding 5.

[0034] However, since the extremely thick winding 5 wound on the teeth 30 is difficult to bend and difficult to follow the teeth 30 and the insulator 40 of the stator core 20, Figure 4 As shown in (C), the winding 5 and the insulator 40 are in close contact only near the boundary between the long side cover 9 and the short side cover 10, and are not in contact with each other at other parts. Therefore, it is difficult to transfer heat from the winding 5 to the stator core 20, resulting in insufficient heat dissipation capacity.

[0035] On the other hand, Figure 1 、 Figure 2 (A) Figure 2 (B) Figure 2 (C) and Figure 3 As shown, in this embodiment, the stator 1 includes: a stator core 2, a plurality of teeth 3 protruding in the radial direction R of the inner circumference of the annular stator core 2 and arranged along the circumferential direction C; an insulator 4 covering the teeth 3; and a winding 5 wound around the teeth 3 via the insulator 4, wherein the teeth 3 have: a pair of long side surfaces 6 extending in the direction along the central axis X of the stator core 2; a pair of short side surfaces 7 extending in a direction intersecting the central axis X; and a through hole portion 8 penetrating from the short side surface 7 on one side to the short side surface 7 on the other side.

[0036] Insulator 4 includes a pair of long-side covering portions 9, each covering the pair of long sides 6; a pair of short-side covering portions 10, each covering the pair of short sides 7; and a through-hole filling portion 11, which fills through-hole portion 8. Long-side covering portions 9 include openings 14 that expose long sides 6. A thermally conductive material 15 having a higher thermal conductivity than insulator 4 is provided in the portion of long sides 6 exposed by openings 14.

[0037] Therefore, heat transfer from the winding 5 to the stator core 2 is facilitated. The long side cover 9 includes an opening 14. However, adjacent long side cover 9 and short side cover 10 are integrated with each other, and the pair of short side cover 10 are integrated with each other via a through-hole filling portion 11. Therefore, the rigidity of the insulator 4 and the stator core 2 can be maintained.

[0038] The rigidity of the insulator 4 is ensured by utilizing the resin's shrinkage during molding to tightly embrace the teeth 3 of the stator core 2. When the insulator 4 completely surrounds the teeth 3 of the stator core 2, the cross-section of the insulator 4 is closed, and the rigidity of the insulator 4 becomes the same as the rigidity of the teeth 3 of the stator core 2 itself, reaching its maximum value.

[0039] On the other hand, when a hole is formed in the long side surface 6, due to molding (mold removal) constraints, the hole is open across the entire long side surface 6 of the tooth 3 of the stator core 2, and the insulator 4 is tightly attached to the tooth 3 only on the short side surface 7. Therefore, the material supporting the insulator 4 near the boundary between the long side surface covering portion 9 and the short side surface covering portion 10 is minimized, reducing rigidity.

[0040] However, in this embodiment, a through hole portion 8 is provided inside the stator core 2, and the short side covering portion 10 located on the short side 7 of the tooth 3 of the stator core 2 is connected by resin filled in the through hole filling portion 11 of the through hole portion 8, so that the insulator 4 is tightly embraced by the tooth 3 of the stator core 2 with the same surface area as that surrounding the surrounding area, thereby maintaining rigidity relatively well.

[0041] As described above, since the extremely thick winding 5 is difficult to bend and difficult to follow the teeth 3 of the stator core 2 and the insulator 4, the winding 5 and the insulator 4 are in close contact only near the boundary between the long side cover portion 9 and the short side cover portion 10. Therefore, if the insulator 4 is in contact with the winding 5 only near this boundary, then the insulator 4 is removed except near this boundary, and the space between the teeth 3 of the stator core 2 and the winding 5 is filled with a thermally conductive material. This makes it easier to transfer heat from the winding 5 to the stator core 2.

[0042] Furthermore, according to this embodiment, each pair of long side covering portions 9 includes two openings 14. These two openings 14 are open at the boundary between the adjacent pair of short side covering portions 10, such that the short side covering portions 10 and the long side faces 6 are flush with each other when viewed along the center axis X. Consequently, undercuts are less likely to occur when insert-molding the insulator 4 around the teeth 3 of the stator core 2 inserted into the mold, facilitating manufacturing. Furthermore, since the pair of long side covering portions 9 each cover the long side faces 6 between the two openings 14, the distance between the winding 5 wound around the teeth 3 via the insulator 4 of the long side covering portions 9 and the teeth 3 is stabilized.

[0043] In other words, when insert molding is used to mold the insulator 4 onto the teeth 3 of the stator core 2, considering that the direction of division of the molding die is along the central axis X, in order to avoid undercutting, the opening 14 needs to be opened so that the short side cover 10 and the long side surface 6 are flush with each other when viewed along the central axis X. In this case, the proximity of the winding 5 to the long side surface 6 becomes a problem.

[0044] Therefore, in this embodiment, the opening 14 is only arranged at the portion of the tooth 3 where the winding 5 does not contact. The insulator 4 is formed in the center of the short side 7 and the long side 6. Figure 3 As shown, the winding 5 is wound around the teeth 3 in a hexagonal or octagonal shape when viewed from the radial direction R, thereby stabilizing the distance between the stator core 2 and the winding 5. Furthermore, this increases the force with which the winding 5 is pressed against the teeth 3 due to tension, thereby reducing the amount of thermally conductive material 15 used and stabilizing the ease of heat transfer.

[0045] Furthermore, in this embodiment, since the extremely thick winding 5 is difficult to bend, the bending of the winding 5 is guided to the middle, and the opening portion 14 serving as the bottom cut-off portion has a surplus thickness relative to the short side 7 of the tooth 3, thereby avoiding contact between the winding 5 and the long side 6 of the tooth 3 and stabilizing the winding of the winding 5 around the tooth 3.

[0046] While the embodiments and variations of the present disclosure have been described above, the present disclosure is not limited to the aforementioned embodiments. For example, the thermally conductive material 15 may be a sheet-shaped thermal conductor interposed between the winding 5 and the teeth 3 of the stator core 2, instead of a thermally conductive compound. Furthermore, the thermally conductive material 15 may be a molding material (potting material) that fills the entire motor, including the opening 14.

[0047] Industrial applicability

[0048] According to the stator of one aspect of the present disclosure, heat is more easily transferred from the winding to the stator core, and the rigidity of the insulator and the stator core can be ensured.

[0049] Description of Reference Numerals

[0050] 1...stator; 2...stator core; 3...tooth; 4...insulator; 5...winding; 6...long side; 7...short side; 8...through-hole portion; 9...long side covering portion; 10...short side covering portion; 11...through-hole filling portion; 12...base covering portion; 13...terminal covering portion; 14...opening portion; 15...thermal conductive material; 16...constricted portion; 17...expanded portion; 20...stator core; 30...tooth; 40...insulator; X...center axis; R...radial direction; C...circumferential direction.

Claims

1. A stator, characterized in that: have: a stator core, wherein a plurality of teeth protrude in a radial direction from an inner circumference of the annular stator core and are arranged in a circumferential direction; an insulator covering the teeth; and a winding wound around the teeth via the insulator, The teeth have: a pair of long side surfaces extending in a direction along a central axis of the stator core; a pair of short side surfaces, adjacent to the long side surfaces and extending in a direction intersecting the central axis; as well as a through hole portion penetrating from one of the short side surfaces to the other short side surface; The insulator has: a pair of long side covering portions, respectively covering the pair of long side surfaces; a pair of short side covering portions, respectively covering the pair of short side surfaces; and a through-hole filling portion, filling the through-hole portion, The long side covering parts and the short side covering parts adjacent to each other are integrated with each other. The pair of short side covering portions are integrated with each other via the through-hole filling portion. The long side covering portion includes an opening portion that exposes and opens the long side. A thermally conductive material having a higher thermal conductivity than the insulator is provided at a portion of the long side surface exposed from the opening.

2. The stator according to claim 1, characterized in that The pair of long side covering portions each includes two opening portions, and the two opening portions are opened at the boundary between the pair of adjacent short side covering portions in such a manner that the short side covering portion and the long side face are flush with each other when viewed from the direction along the central axis. The pair of long side surface covering portions respectively covers the long side surfaces between the two opening portions.

Images