Stator of an electric motor

Abstract

The present invention relates to a stator of an electric motor. The stator disclosed in the present specification comprises a stator core including teeth, coils wound on the teeth in a plurality of turns, and an insulation sheet. The insulation sheet is provided between adjacent ones of the teeth and surrounds at least two turns of the coils. A portion of the insulation sheet is sandwiched between two adjacent turns. A foam material having insulating properties is attached to the portion of the insulation sheet, and the foam material is also sandwiched between the two adjacent turns. By sandwiching the foam material between two specified adjacent turns, high insulation between the two specified turns can be ensured.

Description

Technical Field

[0001] This disclosure relates to the stator of an electric motor. Background Technology

[0002] The stator comprises a stator core and coils wound on teeth of the stator core. Each winding of the coil is called a turn. The windings of the coil are covered with an insulating layer such that adjacent turns are not electrically connected (see, for example, Japanese translation of PCT International Application No. 2024-543611 (JP 2024-543611 A)). When the insulating layer does not provide sufficient insulation, an insulating sheet such as that disclosed in Japanese Unexamined Patent Application Publication No. 2023-101090 (JP 2023-101090 A) can be used. The insulating sheet according to JP 2023-101090 A contains a foaming agent. When the windings are covered with an insulating sheet before foaming and the insulating sheet is foamed after the coil is formed, a coil in which the space between adjacent turns is filled with a foaming agent can be obtained. Summary of the Invention

[0003] When the entire length of the winding is covered with an insulating sheet, the cross-sectional area of ​​the coil (the cross-sectional area obtained when the coil is cut along a plane passing through the axis of the coil) increases. This disclosure provides a stator that ensures the necessary insulation between the turns of the coil while suppressing the increase in the cross-sectional area of ​​the coil.

[0004] One aspect of this disclosure provides a stator for an electric motor. The stator includes: a stator core including teeth; a coil wound on the teeth in a plurality of turns; and an insulating sheet. The insulating sheet is disposed between adjacent teeth and surrounds at least two turns of the coil, a portion of the insulating sheet being sandwiched between two adjacent turns. A foam material having insulating properties is attached to said portion of the insulating sheet. The foam material is sandwiched between two adjacent turns.

[0005] Two physically adjacent turns may not be electrically adjacent, and conversely, two electrically adjacent turns may not be physically adjacent. For example, consider a coil comprising multiple U-shaped coil segments that mesh with teeth. When two physically distant coil segments are electrically connected, a first coil segment positioned immediately adjacent to the second coil segment is physically adjacent to the second coil segment but not electrically adjacent (two electrically connected coil segments are electrically adjacent but not physically adjacent). When current flows through the coil, the potential difference between non-electrically adjacent turns is greater than the potential difference between electrically adjacent turns.

[0006] When a stimulus is applied to the foam material between the two turns, the foam expands and fills the space between the turns, thus increasing the distance between the two turns. In this way, high insulation between the two turns is ensured.

[0007] In the stator according to aspects of this disclosure, the portion of the insulating sheet and the foam material may be sandwiched between two turns that are physically adjacent but not electrically adjacent.

[0008] By sandwiching foam material between two turns, where the potential difference between the two turns is large when current flows, the necessary insulation between the coil turns can be ensured, while suppressing the increase of the coil's cross-sectional area.

[0009] Before expansion, the insulating sheet to which the foam material is attached can retain its folded shape and thus can be easily placed in the slot (the space between adjacent teeth) before the coil is inserted. At this point, the foam material remains in the intended position before expansion. Maintaining the foam material at the predetermined position in the slot before expansion is inexpensive. Stator structures where the foam material has already expanded between adjacent turns can be manufactured at low cost using an insulating sheet to which the foam material is attached before expansion.

[0010] In the stator according to aspects of this disclosure, the starting and ending turns of the coil may be physically adjacent to each other. A portion of the insulating sheet and the foam material may be sandwiched between the starting and ending turns.

[0011] The potential difference between the first and last turns of a coil is greatest when current flows. This allows for increased insulation between the turns, where the potential difference is maximized when current flows.

[0012] In the stator according to aspects of this disclosure, the coil may include a plurality of coil segments having a U-shape and engaging with teeth. Each coil segment may correspond to each turn in the turns. One arm of the U-shape of a designated coil segment may be electrically connected to another arm of another non-physically adjacent coil segment. The designated coil segment and different coil segments disposed adjacent to the designated coil segment may correspond to two physically adjacent but non-electrically adjacent turns. Foam material may be sandwiched between the designated coil segment and the different coil segments disposed adjacent to the designated coil segment.

[0013] A coil in which the insulating sheet is sandwiched between predetermined turns (predetermined segments) can be manufactured at low cost by placing a folded insulating sheet between two adjacent teeth and then inserting a U-shaped coil segment.

[0014] In the stator according to aspects of this disclosure, the insulating sheet may surround all the turns of the coil.

[0015] Details and further improvements to the technology disclosed in this specification will be described in the "Detailed Description" section below. Attached Figure Description

[0016] The features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will now be described with reference to the accompanying drawings, in which the same symbols denote the same elements, and wherein: Figure 1 This is a cross-sectional view of the stator according to the first embodiment; Figure 2 This is the front view of the segment; Figure 3 The electrical connections between multiple turns (segments) are shown; and Figure 4 A method for manufacturing the stator is shown. Detailed Implementation

[0017] The stator 2 according to an embodiment will be described with reference to the accompanying drawings. Figure 1 This is a cross-sectional view of stator 2. Figure 1 This is a cross-sectional view of the cylindrical stator 2, cut along a plane orthogonal to its axis. In the diagram, the Z-axis of the coordinate system is parallel to the axis of stator 2, and the XY plane is parallel to the plane orthogonal to this axis. Figure 1 Only a portion of stator 2 is shown in the image.

[0018] The stator 2 includes a stator core 3 and a coil 10. The stator core 3 is cylindrical and has multiple teeth 4a to 4c on its inner side. The teeth 4a to 4c are arranged along the inner circumference of the cylindrical stator core 3. A coil is wound on every other tooth. The coil 10 is wound on tooth 4a. Figure 1 The lower part shows an enlarged view of the coil 10 wound on the tooth 4a.

[0019] The space between two adjacent teeth (e.g., teeth 4a and 4b) is called slot 5. The winding of coil 10 passes through slot 5.

[0020] Coil 10 consists of multiple U-shaped coil segments. In the following text, for ease of description, "coil segment" will be simply referred to as "segment". Figure 2 This is a front view of segment 11. Figure 2The cross-sections of teeth 4a to 4c are also shown. Segment 11 is made of a conductor (usually copper). Segment 11 mates with tooth 4a. In other words, each arm of segment 11 is inserted into a slot 5 on each side of tooth 4a. For ease of description, one arm of the U-shape of segment 11 will be referred to as right arm 11a, and the other arm will be referred to as left arm 11b. Right arm 11a passes through one side of tooth 4a, and left arm 11b passes through the other side of tooth 4a. Multiple segments mate with one tooth 4a, and the front end of the right arm 11a of one segment 11 is connected to the front end of the left arm 11b of another segment, and the front end of the left arm 11b of segment 11 is connected to the front end of the right arm of yet another segment. In this way, the segments are electrically connected to form a coil 10 wound around tooth 4a. Since one segment 11 surrounds tooth 4a, one segment corresponds to one turn of the coil. In the following text, “segment 11 (coil segment 11)” will also be referred to as “turn 11”.

[0021] Return to Figure 1 The description, in Figure 1 In stator 2, six segments 11 to 16 engage with one tooth 4a. In other words, the six segments 11 to 16 engaging with one tooth 4a constitute one coil 10. As described above, each of the six segments 11 to 16 corresponds to one turn. Figure 1 In this drawing, only reference numeral 11 is given to segment 11 (turn 11), and reference numerals 12 to 16 are not used to indicate the remaining segments (turns). However, in Figure 1 In the diagram, the right and left arms of all turns are given reference numerals. For example, a segment with right arm 16a and left arm 16b corresponds to segment 16 (turn 16). Coil 10 has six turns (turns 11 to 16). The electrical connections between turns 11 to 16 (segments 11 to 16) will be described later.

[0022] The windings of coil 10 are covered with an insulating layer, which is not shown. When current flows through coil 10, the potential difference between two physically adjacent designated turns (turns 11 and 12) is greater than the potential difference between the other two turns. Therefore, in stator 2, a foam material 22 with insulating properties is sandwiched between turns 11 and 12.

[0023] Foam material 22 is attached to one end of insulating sheet 21. Insulating sheet 21 surrounds six turns 11 to 16 between adjacent teeth 4a and 4b (in other words, within slot 5), and one end 21e of insulating sheet 21 is sandwiched between turns 11 and 12. Foam material 22 is attached to said end 21e.

[0024] Foam material 22 expands the gap between turns 11 and 12. Foam material 22 makes the distance between turns 11 and 12 longer than the distance between the other two turns. By making the distance between turns 11 and 12 longer than the distance between the other turns, the insulation between turns 11 and 12 is higher than the insulation between the other turns. A method for manufacturing a stator 2, which includes an insulating sheet 21 to which foam material 22 is attached, will be described later.

[0025] Foam material 22 is disposed only between turns 11 and 12, and not between any other two adjacent turns (e.g., turns 12 and 13 or turns 15 and 16). By sandwiching foam material 22 only between two turns (turns 11 and 12), the potential difference between these two turns is greater than the potential difference between other turns when current flows. This ensures the necessary insulation between adjacent turns while suppressing an increase in the total cross-sectional area of ​​the coil.

[0026] The electrical connection relationship between turns 11 to 16 (segments 11 to 16) will be described. In conjunction with... Figure 1 The lower part is the same Figure 3 In the diagram, the connections between turns (segments) are indicated by thick lines. One end of coil 10 is connected to the inverter, and the other end is connected to the neutral point. For ease of description, one end of coil 10 will be referred to as the starting end, and the other end as the ending end. In coil 10, the front end of the right arm 11a of turn 11 is connected to the inverter, and the front end of the left arm 11b is connected to the front end of the right arm 16a of turn 16. In the following text, for ease of description, the "front end of the right arm (left arm) of the turn" will be simply referred to as the "right arm (left arm) of the turn". The left arm 16b of turn 16 is connected to the right arm 15a of turn 15, and the left arm 15b of turn 15 is connected to the right arm 14a of turn 14. The left arm 14b of turn 14 is connected to the right arm 13a of turn 13, and the left arm 13b of turn 13 is connected to the right arm 12a of turn 12. The left arm 12b of turn 12 is connected to the neutral point. That is, coil 10 is electrically connected in the order of turns 11, 16, 15, 14, 13, and 12. Turns 11 and 16 are electrically adjacent to each other. Similarly, turns 16 and 15, turns 15 and 14, turns 14 and 13, and turns 13 and 12 are electrically adjacent to each other.

[0027] On the other hand, as can be seen from the figure, coil 10 is physically arranged in the order of turns 11, 12, 13, 14, 15, and 16. Turns 11 and 12 are physically adjacent to each other. Similarly, turns 12 and 13, turns 13 and 14, turns 14 and 15, and turns 15 and 16 are physically adjacent to each other.

[0028] Turn 11 corresponds to the beginning of coil 10, and turn 12 corresponds to the end. Turns 11 and 12 are physically adjacent to each other, but not electrically adjacent. When current flows through coil 10, the potential difference between turn 11 corresponding to the beginning and turn 12 corresponding to the end is much greater than the potential difference between other adjacent turns. By sandwiching foam material 22 between turn 11 corresponding to the beginning and turn 12 corresponding to the end, the insulation between turns with a large potential difference can be made higher than the insulation between other turns. That is, the stator 2 can ensure insulation based on the potential difference between adjacent turns.

[0029] In the stator 2 according to the first embodiment, foam material 22 is sandwiched between a pair of turns (turns 11 and 12) that are physically adjacent but not electrically adjacent, and the potential difference between them is greatest when current flows through the coil 10. This ensures the necessary insulation between the turns, where the potential difference is greatest when current flows, while suppressing an increase in the cross-sectional area of ​​the entire coil (the cross-sectional area obtained when the coil is cut along a plane orthogonal to the axis). The potential difference is greatest when turn 11 at the beginning and turn 12 at the end of the coil 10 are adjacent to each other.

[0030] The technology disclosed in this specification is not limited to the case where the potential difference between turns is greatest when current flows. When current flows, the potential difference between physically adjacent but non-electrically adjacent turns is greater than the potential difference between physically adjacent and electrically adjacent turns. Therefore, the technology disclosed in this specification is characterized by foam material 22 sandwiched between two physically adjacent but non-electrically adjacent turns.

[0031] Foam material 22 is attached to one end 21e of insulating sheet 21. Insulating sheet 21 surrounds all turns 11 to 16 of coil 10 between adjacent teeth 4a and 4b. Insulating sheet 21 improves the insulation between coil 10 and teeth 4a and 4b.

[0032] The insulating sheet 21 also helps reduce the manufacturing cost of the stator 2. The insulating sheet 21 is, for example, insulating paper, capable of maintaining its folded shape. (See reference...) Figure 4 Describe the method for manufacturing stator 2. Figure 4 A cross-section of a slot 5 (the space between teeth 4a and 4b) of the stator core 3 is shown. Before inserting segments 11 to 16 into the slot 5, an insulating sheet 21 is placed in the slot 5, and foam material 22a is attached to one end 21e of the insulating sheet 21 before foaming. Figure 4 Part (A)). As described above, the insulating sheet 21 can maintain its folded shape. Before the insertion segment, the insulating sheet 21 is placed in the slot 5 so that the foam material 22a is positioned at the intended location (i.e., between segments 11 and 12) before being foamed.

[0033] Subsequently, segments 11 to 16 are inserted into slot 5. Figure 4 Part (B)). Since the foam material 22a has not yet expanded, segments 11 and 12 can be inserted into the slot 5 with sufficient space. Figure 4 Part (C)). When the right arm 11a (12a to 16a) of segment 11 (12 to 16) is inserted into slot 5, the left arm 11b (12b to 16b) of segment 11 (12 to 16) is inserted into slot 5 between teeth 4a and 4c (see Part C). Figure 1 In other words, the U-shaped segment 11 (12 to 16) engages with the tooth 4, such that the tooth 4a is positioned between the two arms of the U.

[0034] When a specific stimulus is applied, the foam material 22a expands. This specific stimulus can be, for example, ultraviolet light, heat, or a specific reagent. After all segments 11 to 16 are inserted into the slot 5, the specific stimulus is applied to the foam material 22a. The foam material 22a expands and fills the space between segments 11 and 12 without any gaps, thus expanding the distance between segments 11 and 12 ( Figure 4 The foam material 22 in section (D). This ensures high insulation between sections 11 and 12 (turns 11 and 12). For example, a thermosetting resin that foams and expands upon heating and has heat insulation and heat resistance properties is selected as the foam material.

[0035] The insulating sheet 21, to which the foam material 22 is attached before expansion, can maintain its folded shape and thus can be easily placed in the slot 5 before insertion. At this time, the foam material 22a remains in the intended position before expansion. Maintaining the foam material 22a at the predetermined position in the slot 5 before expansion is inexpensive. Figure 4 As shown in sections (A) to (D), the stator 2 in which the foam material 22 has been expanded between adjacent segments 11 and 12 (turns 11 and 12) can be manufactured at low cost using an insulating sheet 21, with the foam material 22a attached to one end 21e of the insulating sheet 21 before expansion.

[0036] Points to note regarding the technology described in the embodiments will be described. An insulating sheet 21 is disposed between adjacent teeth (e.g., teeth 4a and 4b). The length of the insulating sheet 21 in the axial direction of the stator 2 is substantially the same as the length of the stator. In a cross-section obtained by cutting the stator 2 along a plane orthogonal to the axis of the stator 2, the insulating sheet 21 surrounds turns 11 to 16 of the coil 10, and one end 21e is sandwiched between two adjacent turns (turns 11 and 12). Foam material 22 is attached to said end 21e, and foam material 22 is disposed between turns 11 and 12 (segments 11 and 12). Foam material 22 is placed in a slot 5 between turns 11 and 12 (segments 11 and 12) before expansion, and expands between turns 11 and 12 (segments 11 and 12). The expanded foam material fills the space between turns 11 and 12 (segments 11 and 12) and ensures high insulation between turns 11 and 12 (segments 11 and 12).

[0037] An insulating sheet 21, to which foam material 22 is attached, surrounds all turns 11 to 16 within a slot 5. The insulating sheet only needs to surround at least two turns. Two insulating sheets can be disposed in one slot. Foam material can be attached to the end of each insulating sheet, and each foam material can be disposed between a different pair of turns.

[0038] In some cases, the stator coil includes a first tooth and a second tooth, with the first coil wound on the first tooth and the second coil wound on the second tooth. In the technology disclosed in this specification, the location where the foam material is sandwiched (its location in the turn arrangement) may differ between the first and second coils. The technology disclosed in this specification can be applied to stators having coils wound with multiple turns on the teeth.

[0039] The coil 10, composed of multiple segments, has the following characteristics. The coil 10 includes multiple segments 11 to 16 (coil segments 11 to 16) that are U-shaped and engage with teeth 4a. Each segment with a U-shape includes a right arm and a left arm, with the right arm of all segments passing through one side of the teeth 4a and the left arm passing through the other side of the teeth 4a. The front end of the right arm of one segment is electrically connected to the front end of the left arm of another segment, and the front end of the left arm is connected to the front end of the right arm of yet another segment. In this way, the segments form the coil 10 wound around the teeth 4a. The front end of one arm (left arm 11b) of the U-shape of a designated segment (segment 11) is electrically connected to the front end of the other arm (right arm 16a) of a non-physically adjacent segment (segment 16).

[0040] One segment corresponds to one turn. A designated segment (segment 11) and another segment (segment 12) adjacent to the designated segment correspond to two physically adjacent but non-electrically adjacent turns (turns 11 and 12). One end 21e of the insulating sheet 21 and the foam material 22 are sandwiched between the turns.

[0041] When current flows through the coil, the potential difference between two physically adjacent but not electrically adjacent turns is greater than the potential difference between two physically adjacent and electrically adjacent turns. By placing insulating foam material 22 between two physically adjacent but not electrically adjacent turns, and not placing foam material between two physically adjacent and electrically adjacent turns, the necessary insulation between the turns can be ensured while suppressing the increase in the cross-sectional area of ​​the coil.

[0042] The phrase "two physically adjacent turns" refers to a turn being positioned immediately next to another turn. It can also be expressed as "two structurally adjacent turns." The phrase "two electrically adjacent turns" means that one end of one turn is electrically connected to the end of another turn. For example... Figure 3 As shown, the front end of the left arm 11b of turn 11 is electrically connected to the front end of the right arm 16a of turn 16 via a cable. At this point, turns 11 and 16 are electrically adjacent to each other. The other turns (turns 12 to 15) are located between turns 11 and 16, and turns 11 and 16 are not physically adjacent to each other.

[0043] In the stator according to this embodiment, one end of the insulating sheet 21 is sandwiched between two turns, and foam material 22 is attached to said end. One end of the insulating sheet can pass between two adjacent turns. That is, only a portion of the insulating sheet needs to be sandwiched between two turns, and foam material needs to be attached to that portion (the portion sandwiched between two turns). The foam material can be attached to both surfaces of the insulating sheet, or only to one surface of the insulating sheet.

[0044] While specific examples of this disclosure have been described in detail above, they are merely illustrative and not intended to limit the scope of the claims. The technology set forth in the claims includes various modifications and alterations to the specific examples given above. The technical elements indicated in this specification or drawings, individually or in various combinations, demonstrate technical utility and are not limited to the combinations set forth in the originally filed claims. Furthermore, the technology indicated in this specification or drawings can achieve multiple objectives simultaneously, and achieving one of these objectives is itself technically practical.

Claims

1. A stator for an electric motor, characterized in that it comprises: Stator core, the stator core including teeth; A coil, the coil being wound on the teeth with multiple turns; as well as An insulating sheet is disposed between adjacent teeth in the teeth and surrounds at least two turns of the coil, a portion of the insulating sheet is sandwiched between two adjacent turns, wherein an insulating foam material is attached to the portion of the insulating sheet and the foam material is sandwiched between the two adjacent turns.

2. The stator according to claim 1, characterized in that, The portion of the insulating sheet and the foam material are sandwiched between two physically adjacent but non-electrically adjacent turns in the turn.

3. The stator according to claim 2, characterized in that, The starting and ending turns of the coil are physically adjacent to each other, and the portion of the insulating sheet and the foam material are sandwiched between the starting and ending turns.

4. The stator according to any one of claims 1 to 3, characterized in that: The coil includes multiple coil segments, each coil segment being U-shaped and engaging with the teeth; Each coil segment in the coil segment corresponds to each turn in the turn; One arm of the U-shape of a designated coil segment is electrically connected to another arm of a non-physically adjacent coil segment; The specified coil segment and the different coil segments adjacent to the specified coil segment correspond to two physically adjacent but non-electrically adjacent turns; and The foam material is sandwiched between the designated coil segment and the different coil segments arranged adjacent to the designated coil segment.

5. The stator according to claim 1, characterized in that, The insulating sheet surrounds all the turns of the coil.

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