Stator

Abstract

A stator (1) according to one embodiment includes a stator core (2) including teeth (21), and a plurality of coils (5) inserted into the teeth (21). Each tooth (21) has a shape in which the width of the stator (1) in the circumferential direction decreases toward the radially inner side of the stator (1), and the length of the stator (1) in the axial direction increases toward the radially inner side of the stator (1). For example, the stator core (2) includes a plurality of first split cores (3) that are in contact with each other between adjacent teeth (21), and a plurality of second split cores (4) each held by the corresponding one of the first split cores (3).

Description

Stator

[0001] The present disclosure relates to a stator for an electric motor.

[0002] Conventionally, in order to increase the efficiency of electric motors, the teeth of a stator core are tapered radially inward, and the cross-sectional shape of the slots formed between the teeth, which are spaces for inserting coils, is rectangular (see, for example, Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2021-136726

[0004] However, since both end faces of the stator core in the axial direction of the stator are generally parallel to each other, if the teeth are tapered radially inward as described above, the cross-sectional area of ​​each tooth in the direction perpendicular to the radial direction of the stator decreases radially inward of the stator, which causes localized magnetic saturation.

[0005] Therefore, an object of the present disclosure is to provide a stator that can prevent local magnetic saturation while making the cross-sectional shape of the slot rectangular.

[0006] The present disclosure provides a stator comprising a stator core including teeth and a plurality of coils inserted into the teeth, each tooth having a shape such that the width in the circumferential direction of the stator decreases toward the radially inward direction of the stator and the length in the axial direction of the stator increases toward the radially inward direction of the stator.

[0007] According to the present disclosure, a stator is provided that can prevent local magnetic saturation while allowing the cross-sectional shape of the slot to be rectangular.

[0008] Fig. 4 is a perspective view of a stator according to one embodiment; Fig. 5 is a perspective view of the stator with a portion of the coil shown in cross section; Fig. 6 is a front view of the area around one tooth in Fig. 2; Fig. 7 is a cross-sectional view taken along line IV-IV in Fig. 3; Fig. 8 is a cross-sectional view of a portion of a stator according to another modified example; Fig. 9 is a cross-sectional view of a portion of a stator according to another modified example;

[0009] 1 shows a stator 1 according to one embodiment. The stator 1 is hollow, and a rotor is disposed inside the stator 1. The stator 1 and the rotor, together with a rotating shaft that passes through the rotor, constitute an electric motor.

[0010] The stator 1 includes a stator core 2 having teeth 21 and a plurality of coils 5 inserted into the teeth 21. In this embodiment, the number of teeth 21 is 12, but the number of teeth 21 may be 4, 6, 8, 10, 14, etc. Furthermore, an insulating material may be interposed between the coils 5 and the stator core 2.

[0011] As shown in Figure 2, each tooth 21 has a shape in which the width in the circumferential direction of the stator 1 decreases as it moves radially inward of the stator 1, and the length in the axial direction of the stator 1 increases as it moves radially inward of the stator 1.

[0012] In this embodiment, the stator core 2 is divided into a plurality of first divided cores 3, the number of which is equal to the number of teeth 21, and a plurality of second divided cores 4, the number of which is equal to the number of teeth 21. Each tooth 21 is formed by a portion of each first divided core 3 and a second divided core 4.

[0013] The first split cores 3 are in contact with each other between adjacent teeth 21. In other words, the first split cores 3 are lined up continuously in the circumferential direction of the stator 1. The second split cores 4 are each held by the first split cores 3.

[0014] All of the first divided cores 3 have the same shape. In the axial direction of the stator 1, one end face of all of the first divided cores 3 is located on the same plane perpendicular to the axial direction of the stator 1, and the other end faces of all of the first divided cores 3 are located on the same plane perpendicular to the axial direction of the stator 1.

[0015] 3, each first split core 3 includes an arc-shaped yoke portion 31 and a pair of tooth constituent portions 32, 33 that protrude radially inward from the yoke portion 31. The tooth constituent portions 32, 33 are spaced apart from each other in the circumferential direction of the stator 1, and an insertion groove 34 is formed between them. In other words, the bottom of the insertion groove 34 is formed by the yoke portion 31.

[0016] The inner surfaces 32a, 33a of the tooth constituent parts 32, 33 are parallel to each other. The cross-sectional shape of each of the tooth constituent parts 32, 33 in a section perpendicular to the axial direction of the stator 1 is a generally triangular shape that points radially inward of the stator 1. Therefore, the outer surfaces 32b, 33b of the tooth constituent parts 32, 33 are inclined so as to move away from each other radially outward of the stator 1. The outer surfaces 32b, 33b of the tooth constituent parts 32, 33 also form both side surfaces of the tooth 21.

[0017] Protrusions 35 and 36 for holding the coil 5 inserted through the tooth 21 are provided on the outer surfaces 32 b and 33 b of the tooth forming portions 32 and 33 at the ends on the inner side in the radial direction of the stator 1 .

[0018] Each second split core 4 is inserted into the insertion groove 34 of the corresponding first split core 3. In other words, the tooth constituent portions 32, 33 and the second split core 4 form one tooth 21. In addition, in the axial direction of the stator 1, one end face of the tooth constituent portions 32, 33 and one end face of the second split core 4 form one end face of the tooth 21, and the other end face of the tooth constituent portions 32, 33 and the other end face of the second split core 4 form the other end face of the tooth 21.

[0019] As shown in FIG. 4 , each second divided core 4 has a trapezoidal shape that widens radially inward of the stator 1 when viewed from the direction in which the tooth forming portions 32 , 33 of the corresponding first divided core 3 are spaced apart from each other.

[0020] In this embodiment, the length of the base of each second split core 4 on the radially outer side of the stator 1 is equal to the length of the first split core 3 in the axial direction of the stator 1, and the length of the base on the radially inner side of the stator 1 is longer than the length of the first split core 3 in the axial direction of the stator 1. Therefore, the second split core 4 protrudes on both sides from the first split core 3 in the axial direction of the stator 1. Furthermore, the second split core 4 forms an inclined surface on both end faces of the tooth 21 that slopes radially inward of the stator 1 and away from the first split core 3. In this embodiment, the inclined surface is flat from one end on the radially outer side to the other end on the radially inner side of the stator 1, but the inclined surface may have a step along the way.

[0021] In this embodiment, each first divided core 3 has a structure in which multiple electromagnetic steel sheets or amorphous ribbons are laminated in the axial direction of the stator 1, and each second divided core 4 has a structure in which multiple electromagnetic steel sheets or amorphous ribbons are laminated in the direction of separation between the tooth constituent portions 32, 33. Therefore, the first divided core 3 can be manufactured by laminating electromagnetic steel sheets or amorphous ribbons of the same shape, and the second divided core 4 can be manufactured by laminating electromagnetic steel sheets or amorphous ribbons of the same shape. However, either or both of each first divided core 3 and each second divided core 4 may be entirely made of soft magnetic powder.

[0022] Each second divided core 4 is bonded to the corresponding first divided core 3 with an adhesive such as varnish. The first divided cores 3 may be bonded together with an adhesive, or may be inserted into a cylindrical casing to prevent the first divided cores 3 from separating from each other.

[0023] In this embodiment, the coils 5 inserted into each tooth 21 have a rectangular cross-sectional shape on both sides of each tooth 21 in a cross section perpendicular to the axial direction of the stator 1, and the cross-sectional shape of the wire constituting the coils 5 is also rectangular. This increases the cross-sectional area of ​​the coils 5. Note that this effect can be achieved with either a configuration in which the cross-sectional shape of the coils 5 on both sides of each tooth 21 in a cross section perpendicular to the axial direction of the stator 1 is rectangular, or a configuration in which the cross-sectional shape of the wire constituting the coils 5 is rectangular.

[0024] As described above, in the stator 1 of this embodiment, the width of each tooth 21 decreases radially inward, allowing the cross-sectional shape of the slots formed between the teeth 21 to be rectangular. Moreover, the length of the tooth 21 in the axial direction of the stator 1 increases radially inward, allowing the cross-sectional area of ​​each tooth 21 in a direction perpendicular to the radial direction of the stator 1 to be constant regardless of the radial position of the stator 1. This makes it possible to prevent local magnetic saturation.

[0025] Furthermore, in this embodiment, since the second divided core 4 has a trapezoidal shape, the second divided core 4 can have a simple shape.

[0026] <Modifications> The present disclosure is not limited to the above-described embodiment, and various modifications are possible without departing from the gist of the present disclosure.

[0027] For example, the stator core 2 does not necessarily have to be divided into the first split core 3 and the second split core 4, but may be a single piece. When the stator core 2 is a single piece, the coils 5 are formed by winding wire around the teeth 21 due to the shape of the teeth 21. In contrast, if the stator core 2 is divided into the first split core 3 including a pair of tooth constituent portions 32, 33 and the second split core 4 extending on both sides from the first split core 3, an air-core coil can be formed in advance and inserted into the pair of tooth constituent portions 32, 33 of the first split core 3, and then the second split core 4 can be inserted into the insertion groove 34 between the pair of tooth constituent portions 32, 33. Moreover, the first split cores 3 contact each other between adjacent teeth 21, in other words, a first split core 3 is provided for each tooth 21, so that the air-core coil can be easily inserted into the tooth constituent portions 32, 33 of the first split core 3.

[0028] Regarding the coil 5, the cross section of the coil 5 on both sides of each tooth 21 may be rectangular in shape, while the cross section of the wire constituting the coil 5 may be circular in shape, in a cross section perpendicular to the axial direction of the stator 1. Alternatively, if the cross section of the wire constituting the coil 5 is rectangular, the cross section of the coil 5 on both sides of each tooth 21 on a cross section perpendicular to the axial direction of the stator 1 does not have to be rectangular.

[0029] 5, each second split core 4 may have a shape that sandwiches the yoke portion 31 of the first split core 3 from both sides in the axial direction of the stator 1. That is, a fitting groove that fits into the yoke portion 31 may be formed in the end of the second split core 4 that is on the outer side in the radial direction of the stator 1. With this configuration, the relative position of the second split core 4 with respect to the first split core 3 in the axial direction of the stator 1 can be fixed.

[0030] 6, the yoke portion 31 of the first split core 3 may include a through hole 37 that passes through the yoke portion 31 in the axial direction of the stator 1, and each second split core 4 may be divided into a pair of pieces 41 in the axial direction of the stator 1, with each piece 41 including a pin 42 that is inserted into the through hole 37. With this configuration, the relative position of the second split core 4 with respect to the first split core 3 in the radial direction of the stator 1 can be fixed.

[0031] <Summary> In a first aspect, the present disclosure provides a stator comprising a stator core including teeth and a plurality of coils inserted into the teeth, wherein each tooth has a shape such that the width in the circumferential direction of the stator decreases toward the radially inward direction of the stator and the length in the axial direction of the stator increases toward the radially inward direction of the stator.

[0032] With this configuration, the width of each tooth decreases toward the inside in the radial direction, allowing the cross-sectional shape of the slot formed between the teeth to be rectangular. Moreover, the length of each tooth in the axial direction of the stator increases toward the inside in the radial direction, allowing the cross-sectional area of ​​each tooth in the direction perpendicular to the radial direction of the stator to be constant regardless of the radial position of the stator. This prevents local magnetic saturation.

[0033] In a second aspect, the stator core of the first aspect may include a plurality of first divided cores that contact each other between adjacent teeth and a plurality of second divided cores respectively held by the plurality of first divided cores, each of the first divided cores including an arc-shaped yoke portion and a pair of tooth components that protrude radially inward from the yoke portion to form both side surfaces of the tooth and are spaced apart in the circumferential direction of the stator, and each of the second divided cores is inserted into an insertion groove formed between the pair of tooth components of the corresponding first divided core, and protrudes on both sides from the first divided core in the axial direction of the stator to form inclined surfaces on both end surfaces of the tooth that are inclined away from the first divided core toward the radially inner side of the stator. When the stator core is a single piece, coils are formed by winding wire around the teeth due to the shape of the teeth. In contrast, if the stator core is divided into a first split core including a pair of tooth components and a second split core extending on both sides from the first split core, the air-core coil can be formed in advance and inserted into the pair of tooth components of the first split core, and then the second split core can be inserted into the insertion groove between the pair of tooth components. Moreover, since the first split cores contact each other between adjacent teeth, in other words, a first split core is provided for each tooth, the air-core coil can be easily inserted into the tooth components of the first split core.

[0034] As a third aspect, in the second aspect, each of the first divided cores may have a structure in which a plurality of electromagnetic steel sheets or amorphous ribbons are stacked in the axial direction of the stator, and each of the second divided cores may have a structure in which a plurality of electromagnetic steel sheets or amorphous ribbons are stacked in the direction separating the tooth components. With this configuration, the first divided cores can be manufactured by stacking electromagnetic steel sheets or amorphous ribbons of the same shape, and the second divided cores can be manufactured by stacking electromagnetic steel sheets or amorphous ribbons of the same shape.

[0035] As a fourth aspect, in the second or third aspect, each second divided core may have a trapezoidal shape when viewed from the direction in which the tooth component portions of the corresponding first divided core are spaced apart. This configuration allows the second divided core to have a simple shape.

[0036] As a fifth aspect, in the second or third aspect, each of the second divided cores may have a shape that sandwiches the yoke portion of the first divided core from both sides in the axial direction of the stator. With this configuration, the relative position of the second divided core with respect to the first divided core in the axial direction of the stator can be fixed.

[0037] As a sixth aspect, in the second or third aspect, the yoke portion of the first split core may include a through hole that passes through the yoke portion in the axial direction of the stator, and each second split core may be divided into a pair of pieces in the axial direction of the stator, and each piece may include a pin that is inserted into the through hole. With this configuration, the relative position of the second split core with respect to the first split core in the radial direction of the stator can be fixed.

[0038] As a seventh aspect, in any of the first to sixth aspects, the cross-sectional shape of the coil on both sides of each tooth may be rectangular in a cross section taken in a direction perpendicular to the axial direction of the stator, or the cross-sectional shape of the wire constituting the coil may be rectangular. With this configuration, the cross-sectional area of ​​the coil can be increased.

[0039] REFERENCE SIGNS LIST 1 stator 2 stator core 21 teeth 3 first divided core 31 yoke portion 32, 33 tooth forming portion 34 insertion groove 37 through hole 4 second divided core 41 piece 42 pin 5 coil

Claims

1. A stator comprising: a stator core including teeth; and a plurality of coils inserted into the teeth, wherein each tooth has a shape such that its width in the circumferential direction of the stator decreases toward the radially inward direction of the stator, and its length in the axial direction of the stator increases toward the radially inward direction of the stator.

2. The stator described in claim 1, wherein the stator core includes a plurality of first split cores that are in contact with each other between adjacent teeth, and a plurality of second split cores respectively held by the plurality of first split cores, each first split core including an arc-shaped yoke portion and a pair of tooth component parts that protrude radially inward from the yoke portion to form both side surfaces of the tooth and are spaced apart from each other in the circumferential direction of the stator, and each second split core is inserted into an insertion groove formed between the pair of tooth component parts of the corresponding first split core, and protrudes on both sides from the first split core in the axial direction of the stator to form inclined surfaces at both end faces of the tooth that are inclined away from the first split core toward the radially inward side of the stator.

3. A stator as described in claim 2, wherein each first split core has a structure in which a plurality of electromagnetic steel plates or amorphous ribbons are laminated in the axial direction of the stator, and each second split core has a structure in which a plurality of electromagnetic steel plates or amorphous ribbons are laminated in the direction separating the tooth component parts.

4. A stator according to claim 2 or 3, wherein each second split core is trapezoidal when viewed from the direction in which the tooth constituent portions of the corresponding first split core are spaced apart from each other.

5. A stator according to claim 2 or 3, wherein each of the second split cores has a shape that sandwiches the yoke portion of the first split core from both sides in the axial direction of the stator.

6. A stator as claimed in claim 2 or 3, wherein the yoke portion of said first split core includes a through hole passing through said yoke portion in the axial direction of the stator, and each of said second split cores is divided into a pair of pieces in the axial direction of the stator, each piece including a pin to be inserted into said through hole.

7. A stator as claimed in any one of claims 1 to 3, wherein the cross-sectional shape of the coils on both sides of each tooth is rectangular in a cross section perpendicular to the axial direction of the stator, or the cross-sectional shape of the wire constituting the coils is rectangular.

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