Stator and manufacturing method therefor

Abstract

A stator of the present disclosure may comprise a core and a coil wound around the core, wherein the core can include: an outer core having a hollow cylinder shape; and inner cores arranged along the inner circumferential surface of the outer core. The outer core can include: slots which are formed in the radial direction of the outer core from the inner circumferential surface of the outer core and which are spaced apart from each other in the circumferential direction of the outer core; and teeth which are alternately arranged with the slots and which are aligned with the inner cores in the radial direction of the outer core. The coil can be inserted into the slots. A tooth, which is one of the teeth, can include a groove into which the inner core is inserted.

Description

Stator and method for manufacturing the same

[0001] The present disclosure relates to a stator and a method for manufacturing the same. More specifically, the present disclosure relates to a stator for an electric motor and a method for manufacturing the same.

[0002] An electric motor is a device that converts electrical energy into rotational kinetic energy. The electromagnetic interaction between the stator and rotor of an electric motor causes the rotor to rotate at high speeds. The rotational power generated by an electric motor can be used in a variety of products, including electric vehicles. Recently, with the rapid growth of the electric vehicle (EV) market, research into high-speed, high-output electric motors is actively underway.

[0003] However, when the coil is wound around the core by moving it from the outer surface of the stator core toward the inner surface, there is a problem in that the end-turn height of the coil is formed relatively high. In this case, there is a problem in that the coil requirement increases, and the manufacturing cost of the stator increases. There is also a problem in that the resistance of the coil increases, which reduces the performance of the electric motor. In addition, there is a problem in that the volume of the electric motor increases in order to secure the insulation distance from the coil.

[0004] The present disclosure aims to solve the above-mentioned and other problems.

[0005] Another purpose may be to provide a structure that reduces the end-turn height of the coil wound around the core of the stator.

[0006] Another purpose may be to provide a stator having a core that is divided into an outer core and an inner core.

[0007] Another purpose may be to provide a structure that couples the coil and inner core to the outer core by moving them in a direction from the inner surface of the outer core toward the outer surface.

[0008] Another purpose may be to provide a structure that secures the inner cores to the outer core.

[0009] Another purpose may be to provide a structure that can minimize performance degradation of electric motors due to inner cores.

[0010] Another purpose may be to provide a method for manufacturing a stator.

[0011] According to one aspect of the present disclosure for achieving the above or other purposes, a stator comprises a core and a coil wound around the core, wherein the core may include: an outer core having a hollow cylinder shape; and inner cores arranged along an inner circumference of the outer core, wherein the outer core may include: slots formed from the inner circumference of the outer core in a radial direction of the outer core and spaced apart from each other in a circumferential direction of the outer core; and teeth arranged alternately with the slots and aligned with the inner cores in the radial direction of the outer core, wherein the coil may be inserted into the slots, and one of the teeth, a tooth, may include a groove into which the inner core is inserted.

[0012] The effects of the stator and the manufacturing method thereof according to the present disclosure are described as follows.

[0013] According to at least one of the embodiments of the present disclosure, a structure for lowering the end-turn height of a coil wound around a core of a stator can be provided.

[0014] According to at least one of the embodiments of the present disclosure, a stator having a core divided into an outer core and an inner core can be provided.

[0015] According to at least one of the embodiments of the present disclosure, a structure can be provided in which a coil and an inner core are coupled to an outer core by moving in a direction from an inner surface of the outer core toward an outer surface.

[0016] According to at least one of the embodiments of the present disclosure, a structure for fixing inner cores to outer cores can be provided.

[0017] According to at least one of the embodiments of the present disclosure, a structure can be provided that can minimize performance degradation of an electric motor due to inner cores.

[0018] According to at least one of the embodiments of the present disclosure, a method for manufacturing a stator can be provided.

[0019] Further scope of the applicability of the present disclosure will become apparent from the detailed description below. However, since various modifications and variations within the spirit and scope of the present disclosure will become apparent to those skilled in the art, it should be understood that the detailed description and specific examples, such as preferred embodiments of the present disclosure, are given by way of example only.

[0020] FIGS. 1 to 18 are drawings illustrating examples of a stator and a method for manufacturing the same according to embodiments of the present disclosure.

[0021] Hereinafter, embodiments disclosed in this specification will be described in detail with reference to the attached drawings. Regardless of the drawing numbers, identical or similar components are given the same reference numbers and redundant descriptions thereof will be omitted.

[0022] The suffixes "module" and "part" used for components in the following description are given or used interchangeably only for the convenience of writing specifications, and do not have distinct meanings or roles in themselves.

[0023] In addition, when describing the embodiments disclosed in this specification, if it is determined that a detailed description of a related known technology may obscure the gist of the embodiments disclosed in this specification, the detailed description thereof will be omitted. In addition, the attached drawings are only intended to facilitate easy understanding of the embodiments disclosed in this specification, and the technical ideas disclosed in this specification are not limited by the attached drawings, and should be understood to include all modifications, equivalents, and substitutes included in the spirit and technical scope of the present disclosure.

[0024] Terms that include ordinal numbers, such as first, second, etc., may be used to describe various components, but the components are not limited by these terms. These terms are used solely to distinguish one component from another.

[0025] When a component is referred to as being "connected" or "connected" to another component, it should be understood that it may be directly connected or connected to that other component, but that there may be other components intervening. Conversely, when a component is referred to as being "directly connected" or "connected" to another component, it should be understood that there are no other components intervening.

[0026] Singular expressions include plural expressions unless the context clearly indicates otherwise.

[0027] In this application, terms such as “include” or “have” are intended to specify the presence of a feature, number, step, operation, component, part or combination thereof described in the specification, but should be understood not to exclude in advance the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts or combinations thereof.

[0028]

[0029] Referring to FIG. 1, an electric motor (M) may include a stator (1) and a rotor (not shown).

[0030] The stator (1) may have a hollow cylinder shape. A coil (30) may be wound around the stator (1), and current may flow through the coil (30). The coil (30) may be a component of the stator (1).

[0031] The rotor may be positioned inside the stator (1) and may have a cylindrical shape. The rotor and the stator (1) may share a central axis. The rotor may be provided with magnet(s), and when current flows through the coil (30) of the stator (1), the rotor may rotate with respect to the stator (1). A shaft (not shown) may be fixed to the center of the rotor and may rotate together with the rotor. The rotation axis of the shaft may be parallel in the front-rear direction. For example, the shaft may be connected to a drive shaft of an electric vehicle.

[0032]

[0033] Referring to FIGS. 2 and 3, the stator (1) may be referred to as a stator (1) for an electric motor (M). The stator (1) may include an outer core (10). The outer core (10) may be referred to as an outer diameter core (10) or a first core (10). The outer core (10) may have an overall hollow cylinder shape. The outer core (10) may include a yoke (11) and a tooth (12). The tooth (12) may be referred to as an outer tooth (12) or a first tooth (12).

[0034] The yoke (11) can form the outer surface of the outer core (10). The yoke (11) can have a ring-shaped cross-section and can form the outer part of the outer core (10). The yoke (11) can be referred to as the body (11) of the outer core (10).

[0035] The tooth (12) may protrude from the inner surface of the yoke (11). The tooth (12) may protrude from the inner surface of the yoke (11) in the radial direction of the yoke (11). The tooth (12) may extend in an axial direction (A) of the outer core (10). In the axial direction (A) of the outer core (10), one end of the tooth (12) may be parallel to one end of the yoke (11), and the other end of the tooth (12) may be parallel to the other end of the yoke (11). The teeth (12) may be arranged along the inner surface of the yoke (11) and may be spaced apart from each other. The teeth (12) may have the same shape.

[0036] The tooth (12) may include a body (12a) and roots (12b). The root (12b) may be referred to as a rib (12b). The body (12a) and the roots (12b) may extend in the axial direction (A) of the outer core (10). The body (12a) may protrude from the inner surface of the yoke (11) in a direction intersecting the inner surface of the yoke (11). The body (12a) may protrude from the inner surface of the yoke (11) in the radial direction of the yoke (11). The roots (12b) may protrude from the inner end of the body (12a). The height (Hb) at which the roots (12b) protrude from the inner end of the body (12a) may be smaller than the height (Ha) at which the body (12a) protrudes from the inner surface of the yoke (11). The roots (12b) may be spaced apart from each other in the width direction of the body (12a). A groove (12c) of the tooth (12) may be formed between the roots (12b). The depth of the groove (12c) may be equal to the height (Hb).

[0037] A slot (13) may be formed by penetrating both ends of the outer core (10) in the axial direction (A) of the outer core (10). The slot (13) may be formed by being recessed from the inner surface of the outer core (10) in the radial direction of the outer core (10). The bottom (130) of the slot (13) may be located at a certain radius (R13) from the center (O) of the outer core (10), and the tooth (12) may protrude from the bottom (130) of the slot (13) toward the center (O) of the outer core (10). The slot (13) may be formed between the teeth (12). The width (W3) of the slot (13) may be equal to or similar to the width (W2) of the tooth (12). The depth (V3) of the slot (13) may be equal to the sum of the height (Ha) of the body (12a) and the height (Hb) of the roots (12b). A plurality of slots (13) may be alternately arranged with the teeth (12). The number of slots (13) may be equal to the number of teeth (12). For example, the number of slots (13) may be 48. The plurality of slots (13) and the teeth (12) may form an inner part (12, 13) of the outer core (10), and the yoke (11) may form an outer part (11) of the outer core (10). Both the inner part (12, 13) and the outer part (11) may extend in the axial direction (A) of the outer core (10). The slot (13) may be referred to as a first slot (13), and the groove (12c) may be referred to as a second slot (12c).

[0038] The outer core (10) may include plates laminated to each other. The outer core (10) is a collection of thin plates and may be referred to as a lamination core (10). The plates of the outer core (10) may be bonded to each other. The plates of the outer core (10) may be referred to as sheets and may include a metal material such as steel. The plates constituting the outer core (10) may have the same shape and may form the yoke (11), teeth (12), and slots (13) described above.

[0039]

[0040] Referring to Fig. 4, the coil (30) can be formed by continuously bending a conductor into a hairpin shape. The coil (30) can be referred to as a continuous hairpin (30), a wire (30), or a conductor (30). The coil (30) can include a first part (31), a second part (32), a third part (33), a fourth part (34), a fifth part (35), and a sixth part (36) sequentially positioned in one direction (DR3). The one direction (DR3) can be parallel to a direction crossing the coil (30).

[0041] The first part (31) can be elongated in a direction intersecting one direction (DR3). The second part (32) can be bent from an end of the first part (31), and the angle between the second part (32) and the first part (31) can be an obtuse angle. The third part (33) can be bent from an end of the second part (32), and the angle between the third part (33) and the second part (32) can be an obtuse angle. The second and third parts (32, 33) can form a V-shaped bend portion (32, 33, V-shaped bent portion). The fourth part (34) can be bent from an end of the third part (33), and the angle between the fourth part (34) and the third part (33) can be an obtuse angle. The fourth part (34) can be elongated in a direction parallel to the first part (31). The fifth part (35) can be bent from the end of the fourth part (34), and the angle between the fifth part (35) and the fourth part (34) can be an obtuse angle. The sixth part (36) can be bent from the end of the fifth part (35), and the angle between the sixth part (36) and the fifth part (35) can be an obtuse angle. The fifth and sixth parts (35, 36) can form an inverted V-shaped bent portion (35, 36 inverted V-shaped bent portion).

[0042] Next, the first part (31) can be bent from the end of the sixth part (36), and the second to sixth parts (32, 33, 34, 35, 36) can be bent sequentially from the first part (31). That is, in one direction (DR3), a pattern composed of the first to sixth parts (31, 32, 33, 34, 35, 36) can be repeated. The coils (30) arranged along one direction (DR3) can be placed on a two-dimensional (2D) plane.

[0043] The coil (30) may include a plurality of coils (30a, 30b, 30c, 30d, 30e, 30f). The plurality of coils (30a, 30b, 30c, 30d, 30e, 30f) may have the same shape. The plurality of coils (30a, 30b, 30c, 30d, 30e, 30f) may be offset from each other in one direction (DR3). Specifically, the second coil (30b) may be spaced apart from the first coil (30a) by a second distance (Db). The third coil (30c) may be spaced apart from the second coil (30b) by a third distance (Dc) that is greater than the second distance (Db). The fourth coil (30d) can be spaced apart from the third coil (30c) by a fourth distance (Dd) that is equal to the second distance (Db). The fifth coil (30e) can be spaced apart from the fourth coil (30d) by a fifth distance (De) that is equal to the third distance (Dc). The sixth coil (30f) can be spaced apart from the fifth coil (30e) by a sixth distance (Df) that is equal to the fourth distance (Dd).

[0044] Accordingly, the plurality of coils (30a, 30b, 30c, 30d, 30e, 30f) can be arranged along one direction (DR3) and partially overlap each other. The plurality of coils (30a, 30b, 30c, 30d, 30e, 30f) arranged along one direction (DR3) can be placed on a two-dimensional (2D) plane.

[0045] One end of the first coil (30a) and one end of the second coil (30b) can be spaced apart from each other, and the other end of the first coil (30a) and the other end of the second coil (30b) can be spaced apart from each other.

[0046] One end of the third coil (30c) and one end of the fourth coil (30d) can be spaced apart from each other, and the other end of the third coil (30c) and the other end of the fourth coil (30d) can be spaced apart from each other.

[0047] One end of the fifth coil (30e) and one end of the sixth coil (30f) may be spaced apart from each other, and the other end of the fifth coil (30e) and the other end of the sixth coil (30f) may be spaced apart from each other.

[0048] The V-shaped bending portions (32, 33) may be arranged along one direction (DR3) and may be pointed toward the first direction (DR1). The V-shaped bending portions (32, 33) may be referred to as a first end-turn portion (301) or a first crown (301) of the coil (30).

[0049] The inverted V-shaped bending portions (35, 36) may be arranged along one direction (DR3) and may be pointed toward a second direction (DR2). The inverted V-shaped bending portions (35, 36) may be referred to as a second end-turn portion (302) or a second crown (302) of the coil (30).

[0050]

[0051] Referring to FIGS. 5 and 6, the roller (40) may have a cylindrical shape. The roller (40) may be referred to as a magazine (40). A plurality of slots (43) may be recessed from the outer surface of the roller (40) and may be formed to extend in the axial direction (B) of the roller (40). The plurality of slots (43) may be formed by recessing from the outer surface of the roller (40) in the radial direction of the roller (40). The plurality of slots (43) may be spaced apart from each other in the circumferential direction of the roller (40).

[0052] The coil (30) can be positioned on the slots (43) of the roller (40). The first and fourth parts (31, 34) of the coil (30) can extend along the slots (43) and can be inserted into the slots (43). The width of the slot (43) can be equal to or slightly larger than the width of the coil (30). The coil (30) arranged along one direction (DR3) can be placed on a two-dimensional (2D) plane, and a portion of the coil (30) can be inserted into the slots (43) of the roller (40). As the roller (40) rotates, the coil (30) can be gradually wrapped around the roller (40). This can be referred to as a roll-up process. When the coil (30) is wrapped around the roller (40) multiple times, the coil (30) can form multiple layers within the slot (43). The direction in which the above layers are stacked may be parallel to the radial direction of the roller (40). That is, the portion of the coil (30) that is first inserted into a specific slot (43) may be located below the portion of the coil (30) that is later inserted into the specific slot (43).

[0053] A plurality of coils (30a, 30b, 30c, 30d) can be wound around a roller (40). Each of the second distance (Db), the fourth distance (Dd), and the sixth distance (Df) can be equal to the spacing (g) between the slots (43). Each of the third distance (Dc) and the fifth distance (De) can be equal to three times the spacing (g) between the slots (43).

[0054] The length (L3) of the first and fourth parts (31, 34) inserted into the slots (43) may be greater than the length (L4) of the slots (43). Here, the length (L4) of the slots (43) may be equal to the length (L4) of the roller (40). Accordingly, the first and second crowns (301, 302) of the coil (30) wound around the roller (40) may be positioned outside the roller (40).

[0055]

[0056] Referring to FIGS. 7 and 8, a roller (40) around which a coil (30) is wound may be disposed inside the outer core (10) of the stator (1). A radius (Rb) of the roller (40) may be smaller than a radius (Ra) of the outer core (10). The roller (40) may share a central axis (O) with the outer core (10). That is, an axial direction (B) of the roller (40) may be aligned with an axial direction (A) of the outer core (10). Each of the slots (43) of the roller (40) may be aligned with each of the slots (13) of the outer core (10). At this time, the number of slots (43) may be equal to the number of slots (13), and an angle (theta 4) between the slots (43) may be equal to an angle (theta 1) between the slots (13). Accordingly, the coil (30) inserted into each slot (43) of the roller (40) can face each slot (13) of the outer core (10).

[0057] The length (L4) of the roller (40) may be the same as the length (L1) of the outer core (10). Here, the length (L4) of the roller (40) may be the same as the length (L4) of the slot (43), and the length (L1) of the outer core (10) may be the same as the length (L1) of the slot (13). The lengths (L3, see FIGS. 5 and 6) of the first and fourth parts (31, 34) inserted into the slots (43) may be greater than the length (L1) of the slots (13), i.e., the length (L1) of the outer core (10). Accordingly, the first and second crowns (301, 302) of the coil (30) may be located outside the outer core (10).

[0058]

[0059] Referring to FIG. 9, the coil (30) wound around the roller (40) can form multiple layers in each slot (43) of the roller (40). For example, the coil (30) can be overlapped multiple times in each slot (43) to form six layers. The direction in which the layers are stacked can be parallel to the radial direction of the roller (40) and the radial direction of the outer core (10). The cross-section of the coil (30) can be rectangular.

[0060] The coil (30) can be moved from the slot (43) of the roller (40) to the slot (13) of the outer core (10) by a device such as a jig. That is, the coil (30) can be inserted into the slots (43) of the outer core (10). At this time, the coil (30) can be moved in the radial direction (RD) of the outer core (10) from the inner surface of the outer core (10) toward the outer surface. Accordingly, the coil (30) can be wound around the outer core (10).

[0061] The insulating paper (39) can be inserted into each of the plurality of slots (13) and can wrap the side of the coil (30) of each slot (13). The insulating paper (39) can be inserted into each slot (13) while moving in the radial direction (RD) of the outer core (10) from the inner peripheral surface of the outer core (10) toward the outer peripheral surface. For example, after the insulating paper (39) is inserted into each slot (13), the coil (30) can be inserted into each slot (13) through the open portion (39a) of the insulating paper (39), and thereafter, the open portion (39a) of the insulating paper (39) can be closed by bonding or the like. As another example, after the insulating paper (39) is inserted into each slot (43), the coil (30) can be inserted into each slot (43) through the open portion of the insulating paper (39), and then the open portion of the insulating paper (39) can be closed by bonding or the like, and then the insulating paper (39) and the coil (30) can be inserted into each slot (13). Accordingly, the insulating paper (39) can provide electrical insulation between the coil (30) and the outer core (10).

[0062]

[0063] Referring to FIGS. 10 and 11, the stator (1) may include an inner core (20). The inner core (20) may be referred to as an inner core (20) or a second core (20). A plurality of inner cores (20) may be arranged along a circle. The inner cores (20) may be spaced apart from each other (see the distance (g2) between the inner cores (20) in FIG. 10). The inner cores (20) may have the same shape. Each inner core (20) may be elongated in the axial direction (C) of the inner cores (20). The axial direction (C) of the inner cores (20) may be aligned with the axial direction (A, see FIG. 2) of the outer core (10). The inner core (20) may include a tooth (21) and a pole shoe (22). The tooth (21) may be referred to as an inner tooth (21), a second tooth (21), or a body (21). The pole shoe (22) may be referred to as a rib (22).

[0064] The tooth (21) may be elongated. The length (L21) of the tooth (21) may be equal to the length (L1, see FIG. 2) of the outer core (10). The width (W21) of the tooth (21) may be smaller than the length (L21). The cross-section of the tooth (21) may be rectangular. For example, the tooth (21) may include two opposite long sides (21a, 21b) and two opposite short sides (21c, 21d). The width (W21) of the tooth (21) may be defined between the two long sides (21a, 21b), and the thickness (T21) of the tooth (21) may be defined between the two short sides (21c, 21d). The thickness (T21) of the tooth (21) may be greater than the width (W21).

[0065] For example, the first long side (21a) and the second long side (21b) of the tooth (21) may be parallel to each other. As another example, the distance between the first long side (21a) and the second long side (21b) may become smaller as it goes from the first short side (21c) to the second short side (21d). In this case, the angle between the first straight line (L11) extending along the first long side (21a) and the second straight line (L12) extending along the second long side (21b) may be an acute angle.

[0066] The pole shoe (22) may be formed on a lateral side of the tooth (21) and may extend along the tooth (21). The length (L22) of the pole shoe (22) may be the same as the length (L21) of the tooth (21). The pole shoe (22) may be adjacent to an inner end (i.e., a first short side (21c)) of the tooth (21) and may protrude from the lateral side of the tooth (21) in a direction intersecting the tooth (21). The pole shoe (22) may include a first pole shoe (221) and a second pole shoe (222). The first pole shoe (221) may protrude from the first long side (21a) of the tooth (21) and may have a shoe-shaped cross section. A first outer side surface (221a) of the first pole shoe (221) may be adjacent to the tooth (21) and intersect the tooth (21), and may be flat. A second outer side surface (221b) of the first pole shoe (221) may be recessed from the first outer side surface (221a) and may be curved or rounded. A second pole shoe (222) may protrude from the second long side (21b) of the tooth (21) and may have a shoe-shaped cross-section. A first outer side surface (222a) of the second pole shoe (222) may be adjacent to the tooth (21) and intersect the tooth (21), and may be flat. A second outer side surface (222b) of the second pole shoe (222) may be recessed from the first outer side surface (221a) and may be curved or rounded.

[0067] The inner core (20) may include plates laminated to each other. The inner core (20) is a collection of thin plates and may be referred to as a lamination core (20). The plates of the inner core (20) may be bonded to each other. The plates of the inner core (20) may be referred to as sheets and may include a metal material such as steel. The plates constituting the inner core (20) may have the same shape and may form the aforementioned teeth (21) and pole shoes (22). Alternatively, each inner core (20) may be formed as one body.

[0068]

[0069] Referring to FIGS. 12 and 13, the inner core (20) may be aligned with the groove (12c) of the outer core (10). The tooth (21) of the inner core (20) may face the groove (12c) of the outer core (10). The center line (Lr) of the tooth (21) may be aligned with the center line (Lu) of the tooth (12) having the groove (12c). The center lines (Lr, Lu) may be parallel to the radial direction of the outer core (10). The groove (12c) may be a groove having a shape corresponding to the tooth (21) (i.e., a square groove).

[0070] The tooth (21) of the inner core (20) can be inserted into the groove (12c) of the outer core (10). At this time, the inner core (20) can be moved in the radial direction (RD) of the outer core (10) from the inner surface of the outer core (10) toward the outer surface. In this case, not only can the inner core (20) be easily coupled to the outer core (10) compared to the case where the inner core (20) is coupled to the outer core (10) by moving it in the axial direction, but also damage to the inner core (20) and the outer core (10) can be minimized during the coupling.

[0071] The tooth (21) may be referred to as an insertion portion (21). The end of the tooth (21), i.e., the second short side (21d), may face the bottom (12cc) of the groove (12c). The body (12a) of the tooth (12) may form the bottom (12cc) of the groove (12c). The first side wall (12ca) of the groove (12c) may face the first long side (21a) of the tooth (21), and the second side wall (12cb) of the groove (12c) may face the second long side (21b) of the tooth (21). The roots (12ga, 12gb) of the tooth (12) may form the first and second side walls (12ca, 12cb) of the groove (12c).

[0072] For example, the first side wall (12ca) and the second side wall (12cb) may be parallel to each other. In this case, the width (Wc) of the groove (12c) may be defined between the first side wall (12ca) and the second side wall (12cb) and may be constant. The first long side (21a) and the second long side (21b) of the tooth (21) may extend in a direction parallel to or intersecting with each other (see L11, L12 of FIG. 11), and the width (W21) of the tooth (21) may be constant or may become smaller as it approaches the bottom (12cc) of the groove (12c). The constant width (W21) or maximum width (W21) of the tooth (21) may be greater than the constant width (Wc) of the groove (12c).

[0073] For another example, the distance between the first side wall (12ca) and the second side wall (12cb) may become smaller as it gets closer to the bottom (12cc) of the groove (12c). In this case, the width (Wc) of the groove (12c) may be defined between the first side wall (12ca) and the second side wall (12cb), and the maximum width (Wc) may be defined at a position furthest from the bottom (12cc). The first long side (21a) and the second long side (21b) of the tooth (21) may extend in a direction parallel to or intersecting with each other (see L11, L12 of FIG. 11), and the width (W21) of the tooth (21) may be constant or may become smaller as it gets closer to the bottom (12cc) of the groove (12c). The constant width (W21) or maximum width (W21) of the tooth (21) may be greater than the maximum width (Wc) of the groove (12c).

[0074] Accordingly, the tooth (21) of the inner core (20) can be press-fit into the groove (12c) of the outer core (10).

[0075] The protrusion (210) may protrude from the lateral side of the tooth (21). The protrusion (210) may be adjacent to the second short side (21d) of the tooth (21) and may be spaced apart from the pole shoe (22). The protrusion (210) may be formed in a round shape. The first protrusion (211) may protrude from the first long side (21a) of the tooth (21), and the second protrusion (212) may protrude from the second long side (21b) of the tooth (21). In the width direction of the tooth (21), the first and second protrusions (211, 211) may be aligned with each other or arranged in an staggered manner.

[0076] The engaging groove (12g) may be recessed from the side wall of the groove (12c). The engaging groove (12g) may be adjacent to the bottom (12cd) of the groove (12c). The engaging groove (12g) may be a curved concave portion. The engaging groove (12g) may be positioned corresponding to the protrusion (210), and the protrusion (210) may be engaged with the engaging groove (12g). The protrusion (210) may be referred to as a hook (210), and the engaging groove (12g) may be referred to as an insertion groove (12g). The first insertion groove (12ga) may be formed on the first side wall (12ca) of the groove (12c), and the first protrusion (211) may be inserted into the first insertion groove (12ga). A second insertion groove (12gb) can be formed on a second side wall (12cb) of a groove (12c), and a second protrusion (212) can be inserted into the second insertion groove (12gb).

[0077] Accordingly, the protrusion (210) and the catch groove (12g) can couple the tooth (21) of the inner core (20) to the groove (12c) of the outer core (10).

[0078] When the tooth (21) is inserted into the groove (12c), the pole shoes (22) of the inner core (20) can be adjacent to the roots (12b) of the outer core (10). At this time, since the distance (W22) between the end of the first pole shoe (221) and the end of the second pole shoe (222), i.e., the width (W22) of the pole shoe (22), is greater than the width (W21) of the tooth (21), the pole shoe (22) can be caught on the root (12b). The first outer surface (221a) of the first pole shoe (221) can be positioned on the end of the first root (12ba). The first outer surface (222a) of the second pole shoe (222) can be positioned on the end of the second root (12bb). The portion of the pole shoe (22) forming the first outer surfaces (221a, 222a) may be referred to as a stepped portion.

[0079]

[0080] Referring to FIG. 14, the inner cores (20) may be located inside (i.e., hollow space) of the outer core (10). The outer core (10) and the inner cores (20) may be collectively referred to as the divided cores (10, 20) or cores (10, 20) of the stator (1). That is, the cores (10, 20) may be divided into the outer core (10) and the inner cores (20). The inner cores (20) may be arranged along the circumferential direction of the outer core (10). The number of inner cores (20) may be equal to the number of teeth (12) of the outer core (10). For example, the number of inner cores (20) may be 48 (see FIGS. 1 and 2). Each tooth (21) of the inner cores (20) can be inserted and coupled into each groove (12c) of the teeth (12). The inner cores (20) can be spaced apart from each other by a certain distance (g2). The gap (see g2) between the inner cores (20) can be directed toward the slot (13) between the inner cores (20). For this purpose, the distance (W22) between the end of the first pole shoe (221) and the end of the second pole shoe (222), i.e., the width (W22) of the pole shoe (22), can be smaller than the distance (D11) between the slots (13). The distance (D11) between the slots (13) can be equal to the distance (D10) between the grooves (12c).

[0081] For example, the first inner core (20a) and the second inner core (20b) may be next to each other, and the distance (g2) may be the distance between the first pole shoe (221) of the first inner core (20a) and the second pole shoe (222) of the second inner core (20b). The pole shoe (22) may cover a part of the slot (13). The distance (g2) may be smaller than the width (W3, see FIG. 3) of the slot (13) of the outer core (10). The distance (g2) may be smaller than the width (W30) of the coil (30) inserted into the slot (13). Accordingly, the slots (13) of the outer core (10) are opened into a gap between the inner cores (20), but the distance (g2) is formed to be smaller than the width (W30) of the coil (30), so that the performance degradation of the electric motor can be minimized.

[0082] The pole shoe (22) of the inner core (20) can support an insulating paper (39) that wraps around a side surface of the coil (30). For example, the first inner core (20a) can be inserted into a groove (12c) of the first tooth (121), and the second inner core (20b) can be inserted into a groove (12c) of the second tooth (122) adjacent to the first tooth (121). The coil (30) can be inserted into a slot (13) between the first tooth (121) and the second tooth (122), and the insulating paper (39) can wrap around a side surface of the coil (30). A first portion of the insulating paper (39) can be located on a second outer surface (221b) of the first pole shoe (221) of the first inner core (20a). The second part of the insulating paper (39) may be positioned on the second outer surface (222b) of the second pole shoe (222) of the second inner core (20b). The insulating paper (39) may be kept closed by the first pole shoe (221) of the first inner core (20a) and the second pole shoe (222) of the second inner core (20b). That is, the pole shoe (22) of the inner core (20) coupled to the groove (12c) may fix the coil (30) to the slot (13). The portion of the pole shoe (22) forming the second outer surfaces (221b, 222b) may be referred to as a coil engaging portion.

[0083]

[0084] Referring to FIG. 15, a foam material (39F) may be provided on the insulating paper (39). The foam material (39F) may be a foamed epoxy applied to the insulating paper (39) or absorbed into the insulating paper (39). Alternatively, the foam material (39F) may be a foamed insulating paper attached to the insulating paper (39) or constituting the insulating paper (39). The insulating paper (39) may be referred to as a foamed insulating paper (39).

[0085] The foam material (39F) can be foamed when certain conditions (e.g., above a certain temperature) are satisfied, and the foamed foam material (39F) can apply a load to a portion of the outer core (10) that forms a slot (13, see FIG. 14) by expanding. The foamed foam material (39F) can be hardened. Accordingly, the insulating paper (39) and the coil (30) can be firmly fixed to the outer core (10). Meanwhile, a portion of the insulating paper (39) may protrude outside the outer core (10) (see FIG. 1).

[0086]

[0087] Referring to Fig. 16, the manufacturing process of the stator (1) can be composed of 7 steps.

[0088] The first step (S1) may be a step of forming a coil (30) in two dimensions (2D). The first step (S1) may be referred to as a 2D coil forming step (S1). Specifically, the first step (S1) may be a step of continuously bending a conductor into a hairpin shape and arranging it in one direction (DR3), as described above with reference to FIG. 4.

[0089] The second step (S2) may be a step of aligning the coil (30) on the roller (40). The roller (40) may be referred to as a magazine (40). The second step (S2) may be referred to as a step of aligning the coil on the roller (S2). Specifically, the second step (S2) may be a step of aligning and positioning the coil (30) on the slots (43) of the roller (40), as described above with reference to FIGS. 5 and 6.

[0090] The third step (S3) may be a step of winding the coil (30) around a roller (40). The third step (S3) may be referred to as a step of winding the coil around a roller (S3). Alternatively, it may be referred to as a roll-up step (S3). Specifically, the third step (S3) may be a step of winding the coil (30) around the roller (40) by rotating the roller (40), as described above with reference to FIGS. 5 and 6.

[0091] The fourth step (S4) may be a step of aligning the outer core (10) to the roller (40) around which the coil (30) is wound. The outer core (10) may be referred to as an outer core (10) or a first core (10). The fourth step (S4) may be referred to as a step of aligning the outer core with the roller (S4). Specifically, the fourth step (S4) may be a step of positioning the outer core (10) so that each slot (13) of the outer core (10) is aligned with each slot (43) of the roller (40) inside the outer core (10), as described above with reference to FIGS. 7 and 8.

[0092] The fifth step (S5) may be a step of inserting the insulating paper (39) and the coil (30) into the outer core (10). The fifth step (S5) may be referred to as a step of inserting the insulating paper and the coil into the outer core (S5). Alternatively, it may be referred to as a continuous hairpin winding step (S5). Specifically, the fifth step (S5) may be a step of moving the coil (30) and the insulating paper (39) wrapping the side surface of the coil (30) in the radial direction (RD) of the outer core (10) from the inner surface of the outer core (10) toward the outer surface, and inserting and joining them into each slot (43) of the outer core (10), as described above with reference to FIG. 9.

[0093] The sixth step (S6) may be a step of inserting the inner core (20) into the outer core (10). The inner core (20) may be referred to as an inner core (20), a split core (20), or a second core (20). The sixth step (S6) may be referred to as a step of inserting the inner core into the outer core (S6). Specifically, the sixth step may be a step in which each of the inner cores (20) is inserted and coupled into each groove (12c) of each of the teeth (12) of the outer core (10) while moving in the direction from the inner surface of the outer core (10) toward the outer surface in the radial direction (RD) of the outer core (10), as described above with reference to FIG. 14.

[0094] The seventh step (S7) may be a step of foaming and curing the foam material (39F). The seventh step (S7) may be referred to as a step of foaming and hardening (curing) the foam material (S7). Specifically, the seventh step (S7) may be a step in which, as described above with reference to FIG. 16, the foam material (39F) and the insulating paper (39) apply a load to the slot (13) of the outer core (10) by foaming and curing the foam material (39F) by satisfying certain conditions (e.g., above a certain temperature).

[0095]

[0096] Referring to FIGS. 17 and 18 together with FIG. 9, the coil (30) can be inserted into the slot (13) of the outer core (10) while moving in the radial direction (RD) of the outer core (10). At this time, the coil (30) can be moved in a direction from the inner surface of the outer core (10) toward the outer surface. For example, the coil (30) can form six layers within each slot (13). At this time, the coil (30) of the first layer (Y1) can be inserted into the slot (13) first, and the coils (30) of the second to sixth layers (Y2, Y3, Y4, Y5, Y6) can be sequentially inserted into the slot (13).

[0097] The slots (13) of the outer core (10) may be spaced apart from each other by a certain angle (theta 13) with respect to the central axis (O, see FIG. 2) of the outer core (10). Each slot (13) may extend in the radial direction (RD) of the outer core (10). In the radial direction (RD) of the outer core (10), i.e., the direction in which the coil (30) is inserted into the slot (13), the distance between the slots (13) may gradually increase. For example, the fourth part (34) and the first part (31) of the coil (30) may be connected to the fifth and sixth parts (35, 36) forming the second end-turn portion (302). The fourth part (34) can be inserted into the first slot (131), the first part (31) can be inserted into the second slot (132), and four slots (13) can be positioned between the first and second slots (131, 132). As the fourth part (34) of the first layer (Y1) and the first part (31) of the first layer (Y1) are inserted (deeper) into the slots (13), the distance (Ds) between the fourth part (34) and the first part (31) can gradually increase. Correspondingly, the height (Hs) of the second end-turn portion (302) formed by the fifth and sixth parts (35, 36) can gradually decrease.

[0098] Accordingly, while the coil (30) is inserted into the slot (13) of the outer core (10) while moving in the direction from the inner surface of the outer core (10) toward the outer surface, the width of the coil (30) may gradually increase, but the height of the coil (30) may gradually decrease.

[0099] That is, the end-turn portions (301, 302) of the coil (30) located relatively low may be located lower than the end-turn portions (301, 302) of the coil (30) located relatively high. Here, the coil (30) located relatively low may be located closer to the bottom (130) of the slot (13) than the coil (30) located relatively high. In other words, the height of the end-turn portions (301, 302) of the coil (30) of the first layer (Y1) may be the lowest, and the height of the end-turn portions (301, 302) of the coil (30) may increase from the second layer (Y2) to the sixth layer (Y6).

[0100] Alternatively, the heights of the end-turn portions (301, 302) of the coil (30) may be constant in all layers (Y1, Y2, Y3, Y4, Y5, Y6) of the coil (30). In this case, a first crown (301) of a constant height may be formed on one side of the outer core (10), and a second crown (302) of a constant height may be formed on the other side of the outer core (10). For this purpose, before being inserted into the slot (13), the width and height of the coil (30) of each layer may be different from each other.

[0101] Specifically, before being inserted into the slot (13) (see FIG. 8), the coils (30) of the first to sixth layers (Y1, Y2, Y3, Y4, Y5, Y6) may have the following widths and heights. The coil (30) of the first layer (Y1) may have a first width and a first height, and may have end-turn portions (301, 302) bent at a first angle (see theta e). The coil (30) of the second layer (Y2) may have a second width smaller than the first width and a second height lower than the first height, and may have end-turn portions (301, 302) bent at a second angle larger than the first angle. The coil (30) of the third layer (Y3) may have a third width that is smaller than the second width and a third height that is smaller than the second height, and may have end-turn portions (301, 302) bent at a third angle that is larger than the second angle. The coil (30) of the fourth layer (Y4) may have a fourth width that is smaller than the third width and a fourth height that is smaller than the third height, and may have end-turn portions (301, 302) bent at a fourth angle that is larger than the third angle. The coil (30) of the fifth layer (Y5) may have a fifth width that is smaller than the fourth width and a fifth height that is smaller than the fourth height, and may have end-turn portions (301, 302) bent at a fifth angle that is larger than the fourth angle. The coil (30) of the sixth layer (Y6) may have a sixth width smaller than the fifth width and a sixth height smaller than the fifth height, and may have end-turn portions (301, 302) bent at a sixth angle larger than the fifth angle.

[0102] Accordingly, the area occupied by the coil (30) wound around the outer core (10) can be minimized. This can be advantageous in reducing the amount of coil (30) wound around the outer core (10) and lowering the resistance of the coil (30). In addition, this can be advantageous in reducing the volume of the electric motor (M) by reducing the insulation distance with the coil (30).

[0103] Meanwhile, for comparison with the above, a case may be considered in which the coil (30) is inserted into the slot (13) of the outer core (10) while moving from the outer surface of the outer core (10) toward the inner surface. In this case, while the coil (30) is inserted into the slot (13), the width of the coil (30) may gradually narrow, but the height of the coil (30) may gradually increase. That is, when the coil (30) is inserted into the slot (13) of the outer core (10) while moving from the outer surface of the outer core (10) toward the inner surface, the height of the end-turn portions (301, 302) of the coil (30) may increase, and as a result, the area occupied by the coil (30) wound around the outer core (10) may increase. This may result in an increase in the amount of coil (30) wound around the outer core (10) and an increase in the resistance of the coil (30). And, this may result in an increase in the insulation distance from the coil (30), which may increase the volume of the electric motor (M).

[0104]

[0105] Referring to FIGS. 1 to 18, a stator (1) includes a core (10, 20) and a coil (30) wound around the core (10, 20), wherein the core (10, 20) may include: an outer core (10) having a hollow cylinder shape; and inner cores (20) arranged along an inner surface of the outer core (10), wherein the outer core (10) includes: slots (13) formed in a radial direction of the outer core (10) from the inner surface of the outer core (10) and spaced apart from each other in a circumferential direction of the outer core (10); And, it may include teeth (12) that are arranged alternately with the slots (13) and aligned with the inner cores (20) in the radial direction of the outer core (10), the coil (30) may be inserted into the slots (13), and one of the teeth (12) may include a groove (12c) into which the inner core (20) is inserted.

[0106] The above coil (30) can be inserted into the slots (13) while moving in the radial direction of the outer core (10).

[0107] The above coil (30) can be formed by continuously bending the conductor into a hairpin shape.

[0108] The coil (30) can be inserted into the slot (13) while moving in a direction from the inner surface of the outer core (10) toward the outer surface, and can form a plurality of layers in the slot (13), and the height of the end-turn portion (301, 302) of the hairpin forming the coil (30) can be lowered as the layer of the coil (300) gets closer to the bottom (130) of the slot (13).

[0109] The above coil (30) can form a plurality of layers in the slot (13), and the height of the end-turn portion (301, 302) of the hairpin forming the coil (30) can be constant regardless of the layer of the coil (30).

[0110] In the radial direction of the outer core (10), the depth (V3) of the slot (13) may be greater than the depth of the groove (12c).

[0111] The outer core (10) may further include a yoke (11) forming an outer surface of the outer core (10), and the tooth (12) of the outer core (10) may include a body (12a) protruding from the inner surface of the yoke (11), and the groove (12c) may be recessed in the radial direction of the outer core (10) from the inner end of the body (12ㅁ).

[0112] The inner core (20) can be pressed into the groove (12c) of the outer core (10).

[0113] The tooth (12) of the outer core (10) may include a hooking groove (12g) formed on a side wall of the groove (12c) of the tooth (12) of the outer core (10), and the inner core (20) may include a protrusion (210) formed on a lateral side of the inner core (20) and hooked to the hooking groove (12g).

[0114] The inner cores (20) may be spaced apart from each other in the circumferential direction of the outer core (10), and the gap between the inner cores (20) may be directed toward the slot (13) located between the inner cores (20), and may have a width (g2) smaller than the width (W30) of the coil (30) inserted into the slot (13).

[0115] The inner core (20) may include: a tooth (21) inserted into the groove (12c) of the tooth (12) of the outer core (10); and a pole shoe (22) intersecting the tooth (21) of the inner core (20) and hooked onto the tooth (12) of the outer core (10), and the pole shoe (22) may cover a portion of the slot (13).

[0116] The above-described pole shoe (22) of the inner core (20) may include: a first pole shoe (221) protruding from one side of the tooth (21) of the inner core (20); and a second pole shoe (222) protruding from the other side of the tooth (21) of the inner core (20).

[0117] The teeth (12) of the outer core (10) may include: a first tooth (121); and a second tooth (122) spaced apart from the first tooth (121), and the inner core (20) may include: a first inner core (20a) coupled to the first tooth (121); and a second inner core (20b) coupled to the second tooth (122), and the gap between the inner cores (20) may be formed between the first pole shoe (221) of the first inner core (20a) and the second pole shoe (222) of the second inner core (20b), and may face the slot (13) located between the first inner core (20a) and the second inner core (20b).

[0118] The above stator (1) may further include an insulating paper (39) that wraps around the side of the coil (30) inserted into the slot (13), and the insulating paper (39) may be supported by the first pole shoe (221) of the first inner core (20a) and the second pole shoe (222) of the second inner core (20b).

[0119] The above stator (1) may further include: an insulating material (39) that wraps the side of the coil (30) inserted into the slot (13); and a foam material (39F) provided on the insulating material (39).

[0120] A stator (1) comprises: a core (10, 20) and a coil (30) wound around the core (10, 20), wherein the core (10, 20) comprises: an outer core (10) having a hollow cylinder shape; and inner cores (20) arranged along an inner surface of the outer core (10), wherein the outer core (10) comprises: slots (13) formed in a radial direction of the outer core (10) from the inner surface of the outer core (10) and spaced apart from each other in a circumferential direction of the outer core (10); And, it may include teeth (12) that are alternately arranged with the slots (13), and the coil (30) may be moved in one direction from the inner surface of the outer core (10) toward the outer surface and inserted into the slots (13), and the inner cores (20) may be moved in one direction and coupled to the teeth (12).

[0121] The inner core (20) may include a pole shoe (22) intersecting a tooth (12), which is one of the teeth, and the width (W22) of the pole shoe (22) may be larger than the width of the tooth (12), but smaller than the distance (D11) between the slots (13).

[0122] The inner cores (20), the slots (13), and the teeth (12) can extend in the axial direction (A) of the outer core (10).

[0123] An electric motor (M) may include: a stator (1); and a rotor positioned inside the stator (1).

[0124] A method for manufacturing a stator (1) having a core (10, 20) divided into an outer core (10) and inner cores (20) and a coil (30) wound around the core (10) may include: a first step (S5) of moving an insulating paper (39) and the coil (30) in one direction from the inner surface of the outer core (10) toward the outer surface and inserting them into a slot (13) of the outer core (10); and a second step (S6) of moving the inner core (20) in one direction of the outer core (10) and inserting it into a groove (12c) of the outer core (10).

[0125] The above manufacturing method of the stator (1) may further include a third step (S7) of foaming and curing the foam material (39F) of the insulating paper (39).

[0126]

[0127] Any or all of the embodiments of the present disclosure described above are not mutually exclusive or distinct. Any or all of the embodiments of the present disclosure described above may have their respective components or functions combined or used together.

[0128] For example, it means that a configuration A described in a particular embodiment and / or drawing can be combined with a configuration B described in another embodiment and / or drawing. That is, even if a combination between configurations is not directly described, it means that a combination is possible, except in cases where a combination is described as impossible.

[0129] The above detailed description should not be construed as limiting in any respect and should be considered illustrative only. The scope of the present invention should be determined by a reasonable interpretation of the appended claims, and all modifications within the equivalent scope of the present invention are intended to be included within the scope of the present invention.

Claims

1. In a stator having a core and a coil wound around the core, The above cores are: An outer core in the shape of a hollow cylinder; and, Including inner cores arranged along the inner surface of the outer core, The above outer core is: Slots formed in the radial direction of the outer core from the inner surface of the outer core and spaced apart from each other in the circumferential direction of the outer core; and comprising teeth arranged alternately with the slots and aligned with the inner cores in the radial direction of the outer core; The above coils are inserted into the above slots, One of the above teeth is tooth, A stator comprising a groove into which the inner core is inserted.

2. In paragraph 1, The above coil, A stator inserted into the slots while moving in the radial direction of the outer core.

3. In paragraph 2, The above coil, A stator formed by continuously bending the wire into a hairpin shape.

4. In paragraph 3, The above coil, It is inserted into the slot while moving in the direction from the inner surface of the outer core toward the outer surface, and forms a plurality of layers in the slot, The height of the end-turn portion of the hairpin forming the coil is, A stator in which the layer of the coil is lowered as it approaches the bottom of the slot.

5. In paragraph 3, The above coil, Forming multiple layers in the above slot, The height of the end-turn portion of the hairpin forming the coil is, Constant stator regardless of the layer of the above coil.

6. In paragraph 1, In the radial direction of the outer core, the depth of the slot is A stator greater than the depth of the above groove.

7. In paragraph 6, The above outer core is: Further comprising a yoke forming the outer surface of the outer core, The above tooth of the above outer core is, Including a body protruding from the inner surface of the above yoke, The above groove is, A stator that is recessed in the radial direction of the outer core from the inner end of the body.

8. In paragraph 1, The above inner core is, A stator that is pressed into the groove of the outer core.

9. In paragraph 8, The above tooth of the above outer core is, Including a catch groove formed on the side wall of the groove of the tooth of the outer core, The above inner core: A stator formed on a lateral side of the inner core and including a protrusion that engages the engaging groove.

10. In paragraph 1, The above inner cores are, are spaced apart from each other in the circumferential direction of the above outer core, The gap between the above inner cores is A stator facing the slot located between the inner cores and having a width smaller than the width of the coil inserted into the slot.

11. In paragraph 10, The above inner core: A tooth inserted into the groove of the tooth of the outer core; and, A pole shoe intersecting the tooth of the inner core and engaging the tooth of the outer core, The above Paul Shoe, A stator covering a portion of the above slot.

12. In paragraph 11, The above pole shoe of the above inner core: A first pole shoe protruding from one side of the tooth of the inner core; and, A stator including a second pole shoe protruding from the other side of the tooth of the inner core.

13. In paragraph 12, The above tee of the above outer core: First Tooth; and, Including a second tooth spaced apart from the first tooth, The above inner core: A first inner core coupled to the first tooth; and, comprising a second inner core coupled to the second tooth; The gap between the inner cores is A stator formed between the first pole shoe of the first inner core and the second pole shoe of the second inner core, and facing the slot located between the first inner core and the second inner core.

14. In paragraph 13, Further comprising an insulating paper covering the side of the coil inserted into the slot, The above insulation paper, A stator supported by the first pole shoe of the first inner core and the second pole shoe of the second inner core.

15. In paragraph 1, Insulating paper covering the side of the coil inserted into the slot; and, A stator further comprising a foam material provided on the above insulating material.

16. In a stator having a core and a coil wound around the core, The above cores are: An outer core in the shape of a hollow cylinder; and, Including inner cores arranged along the inner surface of the outer core, The above outer core is: Slots formed in the radial direction of the outer core from the inner surface of the outer core and spaced apart from each other in the circumferential direction of the outer core; and Includes teeth arranged alternately with the above slots, The above coil, Moved in one direction from the inner surface of the outer core toward the outer surface and inserted into the slots, The above inner cores are, A stator that moves in the above direction and is coupled to the teeth.

17. In paragraph 16, The above inner core: Includes a pole shoe that intersects one of the teeth, the tooth, The width of the above pole shoe is A stator larger than the width of the above teeth, but smaller than the distance between the above slots.

18. In paragraph 16, The inner cores, the slots, and the teeth, A stator extending in the axial direction of the above outer core.

19. A method for manufacturing a stator having a core divided into an outer core and an inner core and a coil wound around the core, A first step of inserting the insulating paper and the coil into the slot of the outer core by moving them in one direction from the inner surface of the outer core toward the outer surface; and, A method for manufacturing a stator, comprising a second step of moving the inner core in the one direction of the outer core and inserting it into a groove of the outer core.

20. In paragraph 19, A method for manufacturing a stator further comprising a third step of foaming and curing the foam material of the above insulating paper.

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