Stator of an electric motor

Abstract

This specification provides a technology that ensures the necessary insulation between coil turns while suppressing a decrease in coil occupancy. [Solution] The stator disclosed herein comprises a stator core having teeth and a coil with multiple turns wound around the teeth. The windings of the coil pass through a slot between two adjacent teeth. A projection is provided on the side of at least one of the two adjacent teeth, separating two adjacent turns. The projection separates two turns that are physically adjacent but electrically not adjacent.

Description

[[Technical Field]]

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

[0002] A stator includes a stator core and a coil wound around teeth of the stator core. One winding of the coil is called a turn. An insulator is disposed between adjacent turns to prevent conduction between the adjacent turns. For example, the stator disclosed in Patent Document 1 includes a coil bobbin sandwiched between two adjacent teeth. The coil bobbin is made of an insulator and has a plurality of holes arranged in the radial direction of the stator core. A winding passes through each of the holes. The space between adjacent teeth is sometimes called a slot. The coil bobbin is disposed in the slot. [[Prior Art Document]] [[Patent Document]]

[0003] [[Patent Document 1]] Japanese Unexamined Patent Publication No. 2021-126031 [[Summary of the Invention]] [[Problem to be Solved by the Invention]]

[0004] High insulation can be obtained by thickening the wall between adjacent holes of the coil bobbin. However, when the wall of the coil bobbin is thickened, it becomes unavoidable to use a thin winding. In other words, the occupancy of the coil relative to the slot area when viewed from the axial direction of the stator core decreases. This specification provides a technique for securing the necessary insulation between turns of the coil while suppressing a decrease in the coil occupancy. [[Means for Solving the Problem]]

[0005] The stator disclosed herein comprises a stator core having teeth and a coil with multiple turns wound around the teeth. The windings of the coil pass through a slot between two adjacent teeth. A projection is provided on the side of at least one of the two adjacent teeth, separating two adjacent turns. The projection separates two turns that are physically adjacent but electrically not adjacent.

[0006] Two turns may be physically adjacent but not electrically adjacent, and conversely, two turns may be electrically adjacent but not physically adjacent. For example, a coil may contain multiple U-shaped coil segments, and multiple coil segments may be mated to teeth. The tip of one arm of the U-shape of one coil segment is connected to the tip of the other arm of the U-shape of another coil segment. All connected coil segments constitute a coil. When two coil segments that are physically far apart are electrically connected, another coil segment located next to one coil segment will be physically adjacent to that coil segment but not electrically adjacent (two electrically connected coil segments are electrically adjacent but not physically adjacent). When current flows through a coil, the potential difference between turns that are not electrically adjacent is greater than the potential difference between turns that are electrically adjacent.

[0007] In the stator disclosed herein, a protrusion is provided on the side of the teeth (the side facing the turn) to separate two turns that are physically adjacent but not electrically adjacent. There is no need to provide a protrusion between two turns that are both physically and electrically adjacent. If the insulating layer between all turns in the slot is made thicker, the coil's occupancy rate relative to the slot area will decrease. In the technology disclosed herein, by inserting a protrusion between two turns where the potential difference is large when current flows, it is possible to ensure the necessary insulation between coil turns while suppressing the reduction in the cross-sectional area of ​​the winding. In other words, it is possible to ensure the necessary insulation between coil turns while suppressing the reduction in the coil's occupancy rate relative to the slot area.

[0008] The greatest potential difference occurs between the first and last turns of a coil when current flows through it. Therefore, it is desirable for the first and last turns of the coil to be physically adjacent, with a projection separating them. This allows for high insulation between the turns where the potential difference is greatest when current flows through them.

[0009] Multiple protrusions may be provided on the sides of the teeth. That is, at least one of two adjacent teeth may have another protrusion on its side that separates two other adjacent turns.

[0010] As mentioned earlier, the coil may include multiple U-shaped coil segments fitted into the teeth. Each coil segment corresponds to each turn. One arm of the U-shape of a particular coil segment is electrically connected to the other arm of another coil segment that is not physically adjacent. In this case, the projection separates a particular coil segment from the coil segment located next to it. Since the coil is formed by inserting the coil segments between the teeth, it becomes easier to insert the coil segments into the slots (spaces between the teeth) provided by the projections. A stator with projections on the side of the teeth that separate two turns can be manufactured at low cost.

[0011] Details of the technology disclosed herein and further improvements are described in the following "Modes for Carrying Out the Invention". [Brief explanation of the drawing]

[0012] [Figure 1] This is a cross-sectional view of the stator in the embodiment. [Figure 2] This is a front view of the segment. [Figure 3] This diagram shows the electrical connection relationships between multiple turns (segments). [Figure 4] This is a cross-sectional view of the modified stator. [Modes for carrying out the invention]

[0013] The stator 2 of the embodiment will be described with reference to the drawings. Figure 1 is a cross-sectional view of the stator 2. Figure 1 is a cross-sectional view obtained by cutting the stator 2 with a plane perpendicular to the axis of the cylindrical stator 2. In the coordinate system of the figure, the Z axis is parallel to the axis of the stator 2, and the XY plane is perpendicular to the axis. Note that only a part of the stator 2 is shown in Figure 1.

[0014] The stator 2 comprises a stator core 3 and a coil 10. The stator core 3 is cylindrical and has several teeth 4a-4c on its inside. The teeth 4a-4c are arranged along the inner circumference of the cylindrical stator core 3. A coil is wound around every other tooth. The coil 10 is wound around tooth 4a. A magnified view of the coil 10 wound around tooth 4a is shown at the bottom of Figure 1.

[0015] The space between two adjacent teeth (for example, teeth 4a and 4b) is called slot 5. The winding of coil 10 passes through slot 5.

[0016] The coil 10 is composed of multiple U-shaped coil segments. For the sake of explanation, "coil segments" will be simply referred to as "segments" below. Figure 2 shows a front view of one segment 11. Figure 2 also shows a cross-section of teeth 4a-4c. Segment 11 is made of a conductor (typically copper). Segment 11 is fitted onto teeth 4a. In other words, each arm of segment 11 is inserted into the slots 5 on each side of teeth 4a. For the sake of explanation, one U-shaped arm of segment 11 will be referred to as the right arm 11a, and the other arm as the left arm 11b. The right arm 11a passes through one side of teeth 4a, and the left arm 11b passes through the other side of teeth 4a. Multiple segments are fitted to a single tooth 4a, with the tip of the right arm 11a of one segment 11 electrically connected to the tip of the left arm 11b of another segment, and the tip of the left arm 11b of segment 11 electrically connected to the tip of the right arm of yet another segment. In this way, multiple segments are electrically connected to form a coil 10 that is wound around the tooth 4a. Since one segment 11 surrounds the tooth 4a, one segment corresponds to one turn of the coil. Hereafter, "segment 11 (coil segment 11)" will also be referred to as "turn 11".

[0017] Let's return to the explanation of Figure 1. In the stator 2 of Figure 1, six segments 11-16 are fitted to one tooth 4a. In other words, the six segments 11-16 fitted to one tooth 4a constitute one coil 10. As mentioned earlier, each of the six segments 11-16 corresponds to one turn. In Figure 1, only segment 11 (turn 11) is denoted by the symbol 11, and the symbols 12-16 for the remaining segments (turns) are omitted from the illustration. However, in Figure 1, the symbols for the right arm and left arm of all turns are denoted. For example, a segment having a right arm 16a and a left arm 16b corresponds to segment 16 (turn 16). The coil 10 has six turns (turns 11-16). The electrical connection relationships between turns 11-16 (segments 11-16) will be described later.

[0018] The winding of the coil 10 is coated with an insulating layer, but the illustration of the insulating layer is omitted. When a current flows through the coil 10, the potential difference between two specific physically adjacent turns (turn 11 and turn 12) becomes larger than the potential difference between any other two turns. Accordingly, in the stator 2, a protrusion 21 is provided on the side surface 6 of teeth 4a and 4b (4c). The protrusion 21 enters between the adjacent turns 11 and 12, and separates the two turns. The distance between the turns 11 and 12 becomes larger than the distance between any other two turns. The insulation between the turns 11 and 12 becomes higher than the insulation between any other two turns.

[0019] The protrusion extends over the entire length of the stator core 3 in the axial direction (Z-axis direction). Accordingly, inside the stator core 3, the distance between the turns 11 and 12 is constant over the entire length of the stator core 3 in the axial direction (Z-axis direction).

[0020] The protrusion 21 is provided only between the turn 11 and the turn 12, and is not provided between any other two adjacent turns (for example, turns 12 and 13, or turns 15 and 16). By arranging the protrusion 21 only between the two turns (turns 11 and 12) that have a larger potential difference than other turns when a current flows, the stator 2 can suppress a decrease in the coil occupancy rate relative to the cross-sectional area of the slot 5, while ensuring the insulation required between adjacent turns.

[0021] This section explains the electrical connection relationships between multiple turns 11-16 (segments 11-16). Figure 3 is the same as the lower part of Figure 1, but the connections between turns (segments) are shown with thicker lines. "Connection" means an electrical connection. One end of coil 10 is electrically connected to the inverter, and the other end is connected to the neutral point. For the sake of explanation, one end of coil 10 will be called the start end, and the other end will be called the end end. In coil 10, the tip of the right arm 11a of turn 11 is connected to the inverter, and the tip of the left arm 11b is connected to the tip of the right arm 16a of turn 16. Hereafter, for the sake of explanation, the "tip of the right arm (left arm) of the turn" will simply be called 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. In other words, coil 10 is electrically connected in the order of turn 11, turn 16, turn 15, turn 14, turn 13, and turn 12. Turns 11 and 16 are electrically adjacent. Similarly, turns 16 and 15, turn 15 and 14, turn 14 and 13, and turn 13 and 12 are electrically adjacent.

[0022] On the other hand, as can be seen from the diagram, the coil 10 is physically arranged in the order of turns 11, 12, 13, 14, 15, and 16. Turns 11 and 12 are physically adjacent. Similarly, turns 12 and 13, 13 and 14, 14 and 15, and 15 and 16 are physically adjacent.

[0023] Turn 11 corresponds to the start end of the coil 10, and turn 12 corresponds to the finish end of the coil 10. Turn 11 and turn 12 are physically adjacent but not electrically adjacent. When current flows through the coil 10, the potential difference between turn 11 corresponding to the start end and turn 12 corresponding to the finish end is significantly larger than the potential difference between other adjacent turns. By increasing the distance between turn 11 corresponding to the start end and turn 12 corresponding to the finish end via the projection 21, insulation between turns with a large potential difference can be made higher than insulation between other turns. That is, the stator 2 can ensure insulation performance corresponding to the potential difference between adjacent turns.

[0024] Note that insulation between two turns that are both electrically and physically adjacent is ensured by the insulating coating covering the winding. The potential difference between turn 11 and turn 12 is large, and there is a risk that sufficient insulation cannot be ensured only by the coating of the winding. By increasing the distance between turn 11 and turn 12 via the projection 21, sufficient insulation can be ensured between turn 11 and turn 12.

[0025] In the stator 2 of the embodiment, when current is supplied to the coil 10, the projection 21 increases the distance between a pair of turns (turn 11 and turn 12) that are physically adjacent, not electrically adjacent, and have the maximum potential difference. By this means, while suppressing a decrease in the occupancy of the coil 10 relative to the area of the slot 5 when viewed from the axial direction, necessary insulation between the turns that have the maximum potential difference when current flows can be ensured. The maximum potential difference occurs when the turn 11 at the start end and the turn 12 at the finish end of the coil 10 are adjacent to each other.

[0026] A modified example of stator 102 is described. Figure 4 is a cross-sectional view of stator 102. Stator 102 has two projections 21 and 22 on the side surface 6 of teeth 4a (4b, 4c). The projections 21 and 22 of teeth 4a each face the projections 21 and 22 of the adjacent teeth 4b (4c). The projections 21 of teeth 4a and 4b fit between two turns 11 and 12, increasing the distance between them. Another projection 22 of teeth 4a and 4b fits between two turns 15 and 16, increasing the distance between them.

[0027] The thick lines in Figure 4 show the electrical connection relationships of turns 11-16 (coil segments 11-16). In the coil 110 of the stator 102, turns 11-16 are arranged in this order, and turns 11 and 12, 12 and 13, 13 and 14, 14 and 15, and 15 and 16 are physically adjacent. However, as the thick lines in Figure 4 show, turns 11 and 12 are not electrically adjacent. Similarly, turns 15 and 16 are not electrically adjacent.

[0028] In the stator 102, a projection 21 fits between two turns 11 and 12 that are physically adjacent but not electrically adjacent, widening the gap between them. Also in the stator 102, a projection 22 fits between two turns 15 and 16 that are physically adjacent but not electrically adjacent, widening the gap between them. In this way, multiple projections may be provided on the side surface 6 of the teeth, depending on the connection relationships of the multiple turns. Each projection fits between two adjacent turns, widening the gap between them.

[0029] The technology disclosed herein is not limited to the case where the potential difference between turns is maximum when an electric current is applied. When an electric current is applied, the potential difference between physically adjacent but electrically non-adjacent turns is greater than the potential difference between physically and electrically adjacent turns. Therefore, a feature of the technology disclosed herein is that a projection is provided on the side of the teeth so as to fit between two physically adjacent but electrically non-adjacent turns, and the projection widens the distance between the two turns. No projection is placed between two turns that are both physically and electrically adjacent.

[0030] The following points concern the technology described in the examples. There are various ways in which multiple coil segments are connected. The electrical order of turns on one side of a tooth may differ from the electrical order of turns on the other side (for example, when one turn is electrically connected to a turn that is physically wound around an adjacent tooth). Therefore, the position of the protrusion on one side of a tooth (its position in the radial direction of the stator core) may differ from the position of the protrusion on the other side. Alternatively, a protrusion may be provided on one side of a tooth, but not on the other side.

[0031] In some cases, an insulating sheet may be placed on the side of a tooth. In this case, the protrusions on the side of the tooth may curve the insulating sheet, causing it to fit between two adjacent turns and widen the gap between them. In this case, the insulating sheet can also be considered part of the tooth, and therefore, this is included in the expression, "Protrusions are provided on the sides of each of two adjacent teeth, separating two adjacent turns."

[0032] The purpose of the projection is to increase the distance between two adjacent turns. If it is possible to increase the distance between two adjacent turns, it is sufficient to have a projection on the side of at least one of the two adjacent teeth.

[0033] The side of the teeth 6 is, in other words, the side of the slot. That is, the projection 21 (22) only needs to be provided on at least one side of the slot 5 through which the winding of the coil 10 passes.

[0034] The coil 10, which is composed of multiple segments, has the following characteristics: The coil 10 includes multiple U-shaped segments 11-16 (coil segments 11-16) that are fitted onto the teeth 4a. Each U-shaped segment has 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 tip of the right arm of any segment is electrically connected to the tip of the left arm of another segment, and the tip of the left arm is connected to the tip of the right arm of yet another segment. In this way, multiple segments constitute the coil 10 that is wound around the teeth 4a. The tip of one U-shaped arm (left arm 11b) of a particular segment (segment 11) is electrically connected to the tip of the other arm (right arm 16a) of another segment (segment 16) that is not physically adjacent.

[0035] Each segment corresponds to one turn. A particular segment (segment 11) and another segment located next to it (segment 12) correspond to two turns (turns 11 and 12) that are physically adjacent but electrically not adjacent. A projection 21 is provided on the side of the teeth so as to be located between those turns. The projection 21 widens the distance between adjacent turns 11 and 12 compared to the distance between two turns that are physically and electrically adjacent.

[0036] It is also preferable to fill the space expanded by the projection 21(22) with insulating material. This further improves the insulation between the two turns expanded by the projection 21(22).

[0037] When current flows through a coil, the potential difference between two turns that are physically adjacent but not electrically adjacent is greater than the potential difference between two turns that are physically and electrically adjacent. In the stator 2(102) of this embodiment, protrusions 21(22) are placed between two turns that are physically adjacent but not electrically adjacent, and no protrusions are placed between two turns that are physically and electrically adjacent. This feature makes it possible to ensure the necessary insulation between each turn while suppressing the decrease in the coil's occupancy rate relative to the area of ​​the slot 5 when viewed from the axial direction.

[0038] "Two physically adjacent turns" means that one turn is located next to the other. "Two physically adjacent turns" can also be rephrased as "two structurally adjacent turns." "Two electrically adjacent turns" means that the end of one turn is electrically connected to the end of the other turn. As shown in Figure 3, the tip of the left arm 11b of turn 11 is electrically connected to the tip of the right arm 16a of turn 16 by an electrical cable. In this case, turn 11 and turn 16 are electrically adjacent. Another turn (turns 12-15) is located between turn 11 and turn 16, so turn 11 and turn 16 are not physically adjacent.

[0039] Although specific examples of the present invention have been described in detail above, these are merely illustrative and do not limit the scope of the claims. The technologies described in the claims include various modifications and changes to the specific examples illustrated above. The technical elements described in this specification or drawings exhibit 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 in this specification or drawings can achieve multiple objectives simultaneously, and achieving even one of these objectives itself constitutes technical usefulness. [Explanation of Symbols]

[0040] 2, 102: Stator 3: Stator core 4, 4a-4c: Teeth 5: Slot 6: Side of stator 10, 110: Coil 11-16: Turn (coil segment) 11a-16a: Right arm of U-shaped coil segment 11b-16b: Left arm of U-shaped coil segment 21, 22: Protrusion

Claims

1. A stator core having teeth, A coil in which multiple turns are wound around the aforementioned teeth, It is equipped with, The winding of the aforementioned coil passes through the slot between two adjacent teeth. On at least one side of two adjacent teeth, a projection is provided that separates two adjacent turns. Stator of an electric motor.

2. The stator according to claim 1, wherein the projections separate two turns that are physically adjacent but electrically not adjacent.

3. The starting turn and ending turn of the aforementioned coil are physically adjacent to each other. The stator according to claim 2, wherein the projection separates the starting turn and the ending turn.

4. The stator according to claim 1, wherein at least one side of two adjacent teeth is provided with another projection that separates two other adjacent turns.

5. The coil includes a plurality of U-shaped coil segments fitted into the teeth, Each of the coil segments corresponds to each of the turns, One U-shaped arm of a particular coil segment is electrically connected to the other arm of another coil segment that is not physically adjacent. The projection separates the specific coil segment from the coil segment located adjacent to the specific coil segment. A stator according to any one of claims 1 to 4.

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