WO2024252844A1 - Stator and coreless motor - Google Patents

Abstract

A stator (11) comprises a yoke part (2) and a plurality of air core coils (3). The yoke part (2) has an annular shape around the axial center (10) of a rotor. The air core coils (3) are disposed inside the yoke part (2). The yoke part (2) has a body cylindrical part (20) and a movement restricting part (4). The body cylindrical part (20) has the air core coils (3) disposed along the inner peripheral surface (21) thereof and constitutes a back yoke. The movement restricting part (4) projects from the body cylindrical part (20) toward the axial center (10) side. The movement restricting part (4) has an axial direction restricting part (411) and a radial direction restricting part (412). The axial direction restricting part (411) restricts the air core coil (3) from moving in the axial direction in which the axial center (10) extends. The radial direction restricting part (412) restricts the air core coils (3) from moving in the radial direction orthogonal to the axial center (10).

Description

Stator and coreless motor

This disclosure relates to a stator and a coreless motor, and more specifically to a stator including a cylindrical main body portion that constitutes a back yoke and an air-core coil disposed inside the cylindrical main body portion, and a coreless motor including this stator.

Patent Document 1 discloses a conventional brushless motor. In this brushless motor, a winding coil section with a copper pattern printed on a flexible substrate is attached to the inner surface of a hollow cylindrical stator yoke. Since this brushless motor does not have a slotted iron core, it is possible to achieve low loss and low noise.

Japanese Patent Application Publication No. 3-65041

However, in the brushless motor described in Patent Document 1, it was difficult to position or attach the winding coil section to a specified position on the stator yoke section.

The objective of this disclosure is to provide a stator and coreless motor that can easily restrict movement of the air-core coil relative to the yoke portion.

A stator according to one embodiment of the present disclosure includes a yoke portion and a plurality of air-core coils. The yoke portion is annular around the axis of the rotor. The air-core coils are disposed inside the yoke portion. The yoke portion has a main body cylindrical portion and a movement restricting portion. The main body cylindrical portion has the air-core coils disposed along its inner circumferential surface to form a back yoke. The movement restricting portion protrudes toward the axis from the main body cylindrical portion. The movement restricting portion has an axial restricting portion and a radial restricting portion. The axial restricting portion restricts the air-core coils from moving in the axial direction along which the axis extends. The radial restricting portion restricts the air-core coils from moving in a radial direction perpendicular to the axis.

A coreless motor according to one aspect of the present disclosure includes the above stator and the above rotor.

The stator and coreless motor disclosed herein can easily restrict movement of the air-core coil relative to the yoke portion.

FIG. 1 is a cross-sectional view of a coreless motor according to a first embodiment, taken along a cross section perpendicular to the axial direction. FIG. 2A is a cross-sectional view of the coreless motor taken along a cross section passing through the axis of a stator of the coreless motor. FIG. 2B is a cross-sectional view taken along a cross section passing through the axis of the stator, illustrating a manufacturing method of the stator. FIG. 3 is a cross-sectional view taken along a cross section passing through the axis of a stator according to the second embodiment. FIG. 4 is a cross-sectional view of a section passing through the axis of a stator according to the third embodiment. FIG. 5A is a cross-sectional view of a section passing through the axis of a stator according to a fourth embodiment. FIG. 5B is a perspective view of a main part of the stator. FIG. 5C is a plan view of the cylindrical main body portion and the movement restricting portion of the stator. FIG. 6A is a cross-sectional view of a cross section passing through the axis of a stator according to a fifth embodiment. FIG. 6B is a plan view of the cylindrical main body portion and the movement restricting portion of the stator. FIG. 6C is a perspective view of a main part of the stator. FIG. 7 is a cross-sectional view of a section passing through the axis of a stator according to the sixth embodiment. FIG. 8A is a cross-sectional view taken along a cross section passing through the axis of an assembly piece of a stator according to a seventh embodiment. FIG. 8B is a perspective view of the above assembly piece. FIG. 8C is a plan view of the stator. FIG. 9A is a cross-sectional view of a section passing through the axis of a stator according to an eighth embodiment. FIG. 9B is a plan view of the cylindrical main body portion and the movement restricting portion of the stator. FIG. 9C is a perspective view of a main part of the stator. FIG. 10 is a cross-sectional view of a section passing through the axis of a stator according to a ninth embodiment. FIG. 11 is a cross-sectional view of a section passing through the axis of a stator according to the tenth embodiment.

(1) Overview A coreless motor and a stator according to the present disclosure will be described. The embodiments described below are merely some of the various embodiments of the present disclosure, and are not intended to limit the present disclosure. In the following embodiments, specific numerical values and materials may be exemplified, but various changes to other numerical values and materials are possible depending on the design, etc., as long as the object of the present disclosure can be achieved.

The coreless motor 1 (see, for example, FIG. 1) according to the present disclosure comprises a stator 11 and a rotor 12. The stator 11 (see, for example, FIG. 2A and FIG. 2B) comprises a yoke portion 2 and a plurality of air-core coils 3. The yoke portion 2 is annular around the axis 10 of the rotor 12 (see FIG. 1). The air-core coils 3 are disposed inside the yoke portion 2. The yoke portion 2 has a main body tube portion 20 and a movement restricting portion 4. The main body tube portion 20 has the air-core coils 3 disposed along the inner circumferential surface 21 to form a back yoke. The movement restricting portion 4 protrudes toward the axis 10 from the main body tube portion 20. The movement restricting portion 4 has an axial restricting portion 411 and a radial restricting portion 412. The axial restricting portion 411 restricts the air-core coils 3 from moving in the axial direction to which the axis 10 extends. The radial restriction portion 412 restricts the air-core coil 3 from moving in the radial direction perpendicular to the axis 10.

The above-mentioned coreless motor 1 and stator 11 restrict the movement of the air-core coil 3 relative to the yoke portion 2, making it easy to position or attach the air-core coil 3 to the yoke portion 2.

(2) First embodiment A coreless motor 1 and a stator 11 according to a first embodiment will be described with reference to Fig. 1, Fig. 2A, and Fig. 2B. Fig. 1 is a cross-sectional view taken along a cross section perpendicular to the axial direction of the coreless motor 1 according to the first embodiment. Fig. 2A is a cross-sectional view taken along a cross section passing through the axis 10 of the stator 11 of the coreless motor 1 according to the first embodiment. Fig. 2B is a cross-sectional view taken along a cross section passing through the axis 10 of the stator 11 to explain a method of manufacturing the stator 11 according to the first embodiment.

As shown in FIG. 1, the coreless motor 1 includes a stator 11 and a rotor 12. The rotor 12 is disposed inside the stator 11. In other words, the coreless motor 1 is an inner rotor type motor. The coreless motor 1 is also a three-phase AC motor.

(2.1) Rotor The rotor 12 rotates around the axis 10. The rotor 12 has a cylindrical rotating shaft 121 extending in the direction in which the axis 10 extends (hereinafter referred to as the axial direction), a rotor core 122 having an annular shape and into which the rotating shaft 121 is fitted, and a plurality of magnets 123. The rotor core 122 is provided with a plurality of magnets 123 (eight in the illustrated example) spaced apart from one another in the circumferential direction around the axis 10. Adjacent magnets 123 are provided on the rotor core 122 such that different poles are located on the side facing the axis 10. As a result, one pole (e.g., a north pole) and the other pole (e.g., a south pole) are alternately formed on the surface of the rotor core 122 in the circumferential direction around the axis 10. The rotating shaft 121 is attached to a rotating body (not shown) that is the output destination, and transmits torque and power to the rotating body.

(2.2) Stator The stator 11 includes a yoke portion 2 and a plurality of air-core coils 3 .

(2.3) Air-core coil The air-core coil 3 is disposed inside the yoke portion 2, and generates torque in the rotor 12. The air-core coil 3 is composed of a coil winding wound approximately concentrically. The air-core coil 3 does not have a core inside. The inside of the air-core coil 3 is hollow. The air-core coil 3 has an inner circumferential surface 32 facing the hollow portion, and an outer circumferential surface 31 opposite the inner circumferential surface 32.

The stator 11 is provided with a plurality of air-core coils 3. In this embodiment, two air-core coils 3 are provided for each phase of the U, V, and W phases. The magnetic flux generated by the plurality of air-core coils 3 generates an electromagnetic force that rotates the rotor 12.

(2.4) Yoke Part The yoke part 2 is annular around the axis 10 of the rotor 12. The yoke part 2 has a main cylindrical part 20 and a movement restricting part 4.

(2.5) Cylinder Body The cylinder body 20 is formed of a cylinder having an annular shape as viewed in the axial direction, surrounding the rotor 12 on the outside in a direction perpendicular to the axis 10 of the rotor 12 (radial direction). The cylinder body 20 has a plurality of steel plates laminated in the axial direction. The steel plates are formed of electromagnetic steel plates such as silicon steel plates.

As shown in FIG. 2A, the air-core coil 3 is arranged along the inner peripheral surface 21 of the main body tube portion 20, which constitutes the back yoke.

(2.6) End Restriction Section (Movement Restriction Section)
The movement restricting portion 4 protrudes toward the axis 10 (i.e., inward) from the main body cylindrical portion 20. The movement restricting portion 4 restricts the air-core coil 3, which is arranged at a predetermined position along the inner circumferential surface 21 of the main body cylindrical portion 20, from moving relative to the yoke portion 2. The movement restricting portion 4 has an axial direction restricting portion 411 and a radial direction restricting portion 412. In this embodiment, the yoke portion 2 has, as the movement restricting portion 4, an end portion restricting portion 40 formed at an end portion in the axial direction of the main body cylindrical portion 20.

The yoke portion 2 has a first end restriction portion 41. The first end restriction portion 41 is formed at a first end portion (lower side in FIG. 2A) in the axial direction of the main body tube portion 20. The first end restriction portion 41 (end restriction portion 40) has an axial restriction portion 411 and a radial restriction portion 412.

The axial direction restricting portion 411 is a flange piece that protrudes inward (toward the axis 10) from a first end in the axial direction of the main body tube portion 20. This flange piece is an annular inner flange when viewed in the axial direction (see FIG. 1). The axial direction restricting portion 411 is formed over the entire circumferential length of the main body tube portion 20.

The axial direction restricting portion 411 is preferably formed from the same material as the main body tube portion 20. Specifically, the axial direction restricting portion 411 is formed from the same steel plate (particularly electromagnetic steel plate) as the main body tube portion 20.

The axial restriction portion 411 restricts the movement of the air-core coil 3 in the axial direction along which the shaft center 10 extends. More specifically, the axial restriction portion 411 restricts the movement of the outer peripheral surface 31 of the air-core coil 3. When the air-core coil 3 moves along the axial direction toward the axial restriction portion 411, the outer peripheral surface 31 of the air-core coil 3 comes into contact with the axial restriction portion 411, preventing further movement of the air-core coil 3.

The radial regulating portion 412 is a tubular piece that protrudes from the radial tip (inner end) of the axial regulating portion 411 toward the second end side (upper side in FIG. 2A) of the main body tube portion 20 in the axial direction. The radial regulating portion 412 is formed in an annular shape when viewed in the axial direction. The radial regulating portion 412 is formed over the entire circumferential length of the axial regulating portion 411. In other words, the first end regulating portion 41 (end regulating portion 40) is formed over the entire circumferential length of the main body tube portion 20. The radial regulating portion 412 is also disposed in a part of the portion corresponding to the air-core coil 3 in the axial direction. Here, the "portion corresponding to the air-core coil 3" refers to a portion facing the air-core coil 3 in the radial direction perpendicular to the axial direction. The radial regulating portion 412 faces a part of the air-core coil 3 in the radial direction.

The radial regulating portion 412 is preferably formed from the same material as the main body tubular portion 20, and is also preferably formed from the same material as the axial regulating portion 411. Specifically, the radial regulating portion 412 is formed from the same steel plate (particularly electromagnetic steel plate) as the main body tubular portion 20 and the axial regulating portion 411.

The radial restriction portion 412 restricts the air-core coil 3 from moving in a radial direction perpendicular to the axis 10. When the air-core coil 3 moves radially toward the axis 10 (inside), the side of the air-core coil 3 comes into contact with the radial restriction portion 412, preventing the air-core coil 3 from moving any further.

The first end regulating portion 41 is formed integrally with the main body tubular portion 20. Specifically, the main body tubular portion 20 and the axial regulating portion 411 are formed integrally by welding or the like. Similarly, the axial regulating portion 411 and the radial regulating portion 412 are formed integrally by welding or the like.

(2.7) Summary of the First Embodiment The first end restriction portion 41 (end restriction portion 40) formed on the main body tubular portion 20 has an axial restriction portion 411 and a radial restriction portion 412. The axial restriction portion 411 restricts movement of the outer circumferential surface 31 of the air-core coil 3. The radial restriction portion 412 restricts movement of the air-core coil 3 in the radial direction. This makes it difficult for the air-core coil 3 to be positioned at least outside the main body tubular portion 20 in the axial direction, making it easier to position the air-core coil 3 at a predetermined attachment position of the yoke portion 2.

Also, the axial direction restricting portion 411 and the radial direction restricting portion 412 are formed from electromagnetic steel sheets (magnetic material). Therefore, in the magnetic circuit formed by the magnetic flux as shown by the arrow in FIG. 2A, not only the main body tube portion 20 as a back yoke, but also the axial direction restricting portion 411 and the radial direction restricting portion 412 function as a yoke, increasing the inductance.

Also, as shown in FIG. 2B, the air-core coil 3 is inserted and positioned between the main body tube portion 20 and the radial direction restricting portion 412, and with the core jig inserted inside the yoke portion 2, the air-core coil 3 is attached to the yoke portion 2 by casting. This also attaches (fixes) the air-core coil 3 to the yoke portion 2, making it easy to attach the air-core coil 3 to the specified attachment position of the yoke portion 2.

(3) Second embodiment Next, the coreless motor 1 and stator 11 according to the second embodiment will be described with reference to Fig. 3. Fig. 3 is a cross-sectional view of the stator 11 according to the second embodiment, taken along a line passing through the axis 10. Note that the coreless motor 1 and stator 11 according to the second embodiment are largely the same as the coreless motor 1 and stator 11 according to the first embodiment, and therefore the same reference numerals are used, and a description of the overlapping points will be omitted, with the main differences being described.

In the first embodiment, the main body tube portion 20 has an end regulating portion 40 (first end regulating portion 41) only at a first end in the axial direction of the main body tube portion 20, and does not have an end regulating portion 40 at a second end. In contrast, in the second embodiment, the main body tube portion 20 has end regulating portions 40 at both ends in the axial direction.

A first end regulating portion 41 is formed at the first end (lower side in FIG. 3) in the axial direction of the main body tube portion 20. Furthermore, a second end regulating portion 42 is formed at the second end (upper side in FIG. 3) in the axial direction of the main body tube portion 20. The second end regulating portion 42 is made of the same material as the first end regulating portion 41, that is, a steel plate (particularly an electromagnetic steel plate). The second end regulating portion 42 has an axial regulating portion 421 and a radial regulating portion 422. The axial regulating portion 421 is a flange piece similar to the axial regulating portion 411, but differs in that it protrudes inward (toward the axis 10) from the second end in the axial direction of the main body tube portion 20 as shown in FIG. 3. In addition, the radial regulating portion 422 is a tube piece similar to the radial regulating portion 412, but differs in that it protrudes from the radial tip (inner end) of the axial regulating portion 421 toward the first end side of the main body tube portion 20 in the axial direction (lower side in FIG. 3).

The second end regulating portion 42 is formed as a separate body from the main body tube portion 20. After the air-core coil 3 is inserted between the main body tube portion 20 and the radial regulating portion 412 of the first end regulating portion 41, the second end regulating portion 42 is attached to the second end in the axial direction of the main body tube portion 20. The second end regulating portion 42 is attached to the main body tube portion 20 by welding or the like, but may also be fastened with screws or the like, and the attachment method is not particularly limited.

By providing the first end restriction portion 41 and the second end restriction portion 42, movement of the air-core coil 3 in both axial directions is restricted. This makes it easier to more firmly position and attach (fix) the air-core coil 3 to the yoke portion 2.

(4) Third embodiment Next, a coreless motor 1 and a stator 11 according to a third embodiment will be described with reference to Fig. 4. Fig. 4 is a cross-sectional view of a section passing through the axis 10 of the stator 11 according to the third embodiment. Note that the coreless motor 1 and the stator 11 according to the third embodiment are largely the same as the coreless motor 1 and the stator 11 according to the first embodiment, so the same reference numerals are used, and a description of the overlapping points will be omitted, with the main differences being described.

In the first embodiment, the radial regulating portion 412 is disposed in a portion of the portion corresponding to the air-core coil 3 in the axial direction. In contrast, in the third embodiment, the radial regulating portion 412 is disposed over the entire axial length of the main body tube portion 20. Note that the radial regulating portion 412 according to the third embodiment only needs to be disposed over at least the entire axial length of the portion corresponding to the air-core coil 3.

The radial restriction portion 412 according to the third embodiment is disposed over at least the entire length of the portion corresponding to the air-core coil 3 in the axial direction, which facilitates more secure positioning and attachment (fixing) of the air-core coil 3 to the yoke portion 2.

In particular, when attaching the air-core coil 3 to the yoke portion 2 by casting, casting can be performed without the need for a core jig as in the first embodiment.

(5) Fourth embodiment Next, a coreless motor 1 and a stator 11 according to a fourth embodiment will be described with reference to Figures 5A to 5C. Figure 5A is a cross-sectional view of a section passing through the axis 10 of the stator 11 according to the fourth embodiment. Figure 5B is a perspective view of a main portion of the stator 11 according to the fourth embodiment. Figure 5C is a plan view of the main body tubular portion 20 and the movement restricting portion 4 of the stator 11 according to the fourth embodiment. Note that the coreless motor 1 and the stator 11 according to the fourth embodiment are largely the same as the coreless motor 1 and the stator 11 according to the first embodiment, and therefore the same reference numerals are used, a description of the overlapping points will be omitted, and mainly the differences will be described.

In the first embodiment, the end restriction portion 40 does not specifically restrict the air-core coil 3 from moving in the circumferential direction about the axis 10. In contrast, in the fourth embodiment, the end restriction portion 40 has a plurality of circumferential restriction portions 43 that restrict the air-core coil 3 from moving in the circumferential direction about the axis 10.

The circumferential regulating portions 43 are rib pieces that protrude axially toward the second end side (upper side in FIG. 5A) of the main body tube portion 20, spaced apart in the circumferential direction of the axial regulating portion 411, over the entire radial length of the axial regulating portion 411. The circumferential regulating portion 43 is formed at the boundary portion of the location where the air-core coils 3 are arranged. In other words, the circumferential regulating portion 43 is formed at a bisecting position between the centers of two adjacent air-core coils 3, among the multiple air-core coils 3 arranged at predetermined positions, in the circumferential direction of the axial regulating portion 411.

The circumferential regulating portion 43 is disposed in a portion of the portion corresponding to the air-core coil 3 in the axial direction. The axial length of the circumferential regulating portion 43 is the same as the axial length of the radial regulating portion 412.

The circumferential regulating portion 43 is formed from the same steel plate (particularly electromagnetic steel plate) as the main body tube portion 20, the axial regulating portion 411, and the radial regulating portion 412.

The circumferential regulating portion 43 is provided on the end regulating portion 40, thereby regulating the circumferential movement of the air-core coil 3.

(6) Fifth embodiment Next, a coreless motor 1 and a stator 11 according to a fifth embodiment will be described with reference to Figures 6A to 6C. Figure 6A is a cross-sectional view of a section passing through the axis 10 of the stator 11 according to the fifth embodiment. Figure 6B is a plan view of the main body tubular portion 20 and the movement restricting portion 4 of the stator 11 according to the fifth embodiment. Figure 6C is a perspective view of a main portion of the stator 11 according to the fifth embodiment. Note that the coreless motor 1 and the stator 11 according to the fifth embodiment are largely the same as the coreless motor 1 and the stator 11 according to the first embodiment, and therefore the same reference numerals are used, and a description of the overlapping points will be omitted, with the main differences being described.

In the fifth embodiment, a groove 22 for holding a lead wire connected to the air-core coil 3 is formed at the axial end of the main body tube 20. To explain further, the main body tube 20 has a non-movement restricted end that does not have an end restriction portion 40 at one of both ends in the axial direction of the main body tube 20 (the upper side in FIG. 6A). The groove 22 is formed at this non-movement restricted end.

By forming the grooves 22 in the main body tube portion 20, the lead wires can be passed through the inside and outside of the main body tube portion 20. In addition, since the grooves 22 are formed at the ends of the main body tube portion 20 in the axial direction, the grooves 22 can be easily formed.

(7) Sixth embodiment Next, a coreless motor 1 and a stator 11 according to a sixth embodiment will be described with reference to Fig. 7. Fig. 7 is a cross-sectional view of a section passing through the axis 10 of the stator 11 according to the sixth embodiment. Note that the coreless motor 1 and the stator 11 according to the sixth embodiment are largely the same as the coreless motor 1 and the stator 11 according to the first embodiment, so the same reference numerals are used, and a description of the overlapping points will be omitted, with the main differences being described.

In the first embodiment, the yoke portion 2 has an end restriction portion 40 formed at the end of the main body tube portion 20 in the axial direction as the movement restriction portion 4. In contrast, in the sixth embodiment, the yoke portion 2 has a middle restriction portion 44 formed at the middle portion of the main body tube portion 20 in the axial direction as the movement restriction portion 4.

The yoke portion 2 has a plurality of first intermediate portion regulating portions 45 and a plurality of second intermediate portion regulating portions 46 as the intermediate portion regulating portion 44. The first intermediate portion regulating portions 45 are formed on one end side of the main body tubular portion 20 in the axial direction. The second intermediate portion regulating portions 46 are formed on the other end side of the main body tubular portion 20 in the axial direction.

The first intermediate regulating portion 45 has an axial regulating portion 451 and a radial regulating portion 452. The axial regulating portion 451 is a protruding piece that protrudes inward (toward the axis 10) from a portion of the main body tubular portion 20 that is closer to the first end portion (lower side in FIG. 7) than the center portion in the axial direction. The protruding pieces are formed at intervals in the circumferential direction of the main body tubular portion 20.

The axial direction restricting portion 451 is preferably formed from the same material as the main body tube portion 20. Specifically, the axial direction restricting portion 451 is formed from the same steel plate (particularly electromagnetic steel plate) as the main body tube portion 20.

The axial direction restricting portion 451 restricts the movement of the air-core coil 3 in the axial direction along which the shaft center 10 extends. More specifically, the axial direction restricting portion 451 restricts the movement of the air-core coil 3 toward the second end side of the inner circumferential surface 32 (upward in FIG. 7).

The radial regulating portion 452 is a protruding piece that protrudes from the radial tip (inner end) of the axial regulating portion 451 toward the first end side (lower side in FIG. 7) of the main body tube portion 20 in the axial direction. The radial regulating portion 452 regulates the air-core coil 3 from moving in the radial direction.

The second intermediate regulating portion 46 has an axial regulating portion 461 and a radial regulating portion 462. The axial regulating portion 461 is a protruding piece that protrudes inward (toward the axis 10) from a portion of the main body tubular portion 20 that is closer to the second end (upper side in FIG. 7) than the center in the axial direction. The protruding pieces are formed at intervals in the circumferential direction of the main body tubular portion 20.

The axial direction restricting portion 461 restricts the movement of the air-core coil 3 in the axial direction along which the shaft center 10 extends. More specifically, the axial direction restricting portion 461 restricts the movement of the air-core coil 3 toward the first end side of the inner circumferential surface 32 (the lower side in FIG. 7).

The radial regulating portion 462 is a protruding piece that protrudes from the radial tip (inner end) of the axial regulating portion 461 toward the second end of the main body tube portion 20 in the axial direction. The radial regulating portion 462 regulates the air-core coil 3 from moving in the radial direction.

To attach the air-core coil 3 to the middle regulating portion 44, the air-core coil 3 is stretched in one direction. The hollow portion of the stretched air-core coil 3 is aligned in the axial direction, and the tips of the radial regulating portion 452 and the radial regulating portion 462 are made to pass over the hollow portion, and the air-core coil 3 is disposed between the inner circumferential surface 21 of the main body tube portion 20 and the radial regulating portion 452 and the radial regulating portion 462.

The middle restriction portion 44, like the end restriction portion 40, is formed integrally with the main body tube portion 20.

This makes it easier to more firmly position and attach (fix) the air-core coil 3 to the yoke portion 2.

(8) Seventh Embodiment Next, a coreless motor 1 and a stator 11 according to a seventh embodiment will be described with reference to Figures 8A to 8C. Figure 8A is a cross-sectional view of an assembly piece 201 of the stator 11 according to the seventh embodiment, taken along a line passing through the axis 10. Figure 8B is a perspective view of the assembly piece 201 of the stator 11 according to the seventh embodiment. Figure 8B is a plan view of the stator 11 according to the seventh embodiment. Note that the coreless motor 1 and the stator 11 according to the seventh embodiment are largely the same as the coreless motor 1 and the stator 11 according to the first embodiment, and therefore the same reference numerals are used, a description of the overlapping points will be omitted, and mainly the differences will be described.

In the seventh embodiment, as shown in FIG. 8C, the main body tube portion 20 is configured with a plurality of assembly pieces 201 that are attached to the middle portion regulating portion 44 and are arranged in the circumferential direction of the axis 10. Adjacent assembly pieces 201 are connected to each other or integrated with weld marks between them.

As shown in Figures 8A and 8B, each assembly piece 201 has a middle regulating portion 44 (a first middle regulating portion 45 and a second middle regulating portion 46).

As a result, the air-core coil 3 can be easily attached to the assembly pieces 201 (the tubular main body portion 20) because it is sufficient to attach the air-core coil 3 to the middle restriction portion 44 of the assembly pieces 201 before they are assembled to the tubular main body portion 20. After the air-core coil 3 is attached to each assembly piece 201, adjacent assembly pieces 201 are joined together by screws or welded to form an integrated body tubular portion 20 as a whole.

(9) Eighth embodiment Next, a coreless motor 1 and a stator 11 according to an eighth embodiment will be described with reference to Figures 9A to 9C. Figure 9A is a cross-sectional view of a cross section passing through the axis 10 of the stator 11 according to the eighth embodiment. Figure 9B is a plan view of the main body tubular portion 20 and the movement restricting portion 4 of the stator 11 according to the eighth embodiment. Figure 9C is a perspective view of a main portion of the stator 11 according to the eighth embodiment. Note that the coreless motor 1 and the stator 11 according to the eighth embodiment are largely the same as the coreless motor 1 and the stator 11 according to the sixth embodiment, and therefore the same reference numerals are used, and explanations of overlapping points will be omitted, with the main differences being explained.

In the eighth embodiment, a groove 22 for holding a lead wire connected to the air-core coil 3 is formed at the axial end of the main body tube portion 20. In other words, the coreless motor 1 and stator 11 of the eighth embodiment are the coreless motor 1 and stator 11 of the sixth embodiment (see FIG. 7) with the groove 22 of the fifth embodiment (see FIG. 6A to FIG. 6C) formed.

By forming the grooves 22 in the main body tube portion 20, the lead wires can be passed through the inside and outside of the main body tube portion 20. In addition, since the grooves 22 are formed at the ends of the main body tube portion 20 in the axial direction, the grooves 22 can be easily formed.

(10) Ninth embodiment Next, a coreless motor 1 and a stator 11 according to a ninth embodiment will be described with reference to Fig. 10. Fig. 10 is a cross-sectional view of a section passing through the axis 10 of the stator 11 according to the ninth embodiment. Note that the coreless motor 1 and the stator 11 according to the ninth embodiment are largely the same as the coreless motor 1 and the stator 11 according to the first embodiment, so the same reference numerals are used, and a description of the overlapping points will be omitted, with the main differences being described.

In the ninth embodiment, the yoke portion 2 has an end portion 40 and a middle portion 44 as the movement restriction portion 4.

A first end regulating portion 41 is formed as the end regulating portion 40. The first end regulating portion 41 is formed at the end in the axial direction of the main body tubular portion 20. The middle regulating portion 44 is formed in the middle portion in the axial direction of the main body tubular portion 20. A first middle regulating portion 45 and a second middle regulating portion 46 are formed as the middle regulating portion 44. In other words, the coreless motor 1 and stator 11 of the ninth embodiment are obtained by forming the middle regulating portion 44 of the sixth embodiment (see FIG. 7) on the coreless motor 1 and stator 11 of the first embodiment (see FIG. 2A).

This makes it easier to more firmly position and attach (fix) the air-core coil 3 to the yoke portion 2.

(11) Tenth embodiment Next, the coreless motor 1 and stator 11 according to the tenth embodiment will be described with reference to Fig. 11. Fig. 11 is a cross-sectional view of a section passing through the axis 10 of the stator 11 according to the tenth embodiment. Note that the coreless motor 1 and stator 11 according to the tenth embodiment are largely the same as the coreless motor 1 and stator 11 according to the second embodiment, so the same reference numerals are used, and a description of the overlapping points will be omitted, with the main differences being described.

In the tenth embodiment, the yoke portion 2 has an end portion 40 and a middle portion 44 as the movement restriction portion 4.

The end regulating portion 40 is formed as a first end regulating portion 41 and a second end regulating portion 42. The middle regulating portion 44 is formed as a first middle regulating portion 45 and a second middle regulating portion 46. That is, the coreless motor 1 and stator 11 according to the tenth embodiment are obtained by adding the middle regulating portion 44 (see FIG. 7) of the sixth embodiment to the coreless motor 1 and stator 11 (see FIG. 3) according to the second embodiment.

This makes it easier to more firmly position and attach (fix) the air-core coil 3 to the yoke portion 2.

(12) Modifications Next, modifications will be listed. The following modifications may be implemented in appropriate combination.

The coreless motor 1 is not limited to a three-phase AC motor.

The rotor 12 is not limited to the rotor 12 in the above-described embodiment.

The number of air-core coils 3 provided in the stator 11 is not limited. The air-core coils 3 do not have a core (core) with a magnetic material inside. In other words, the air-core coils 3 have a space with no object inside, or have an object made of a non-magnetic material. It is acceptable for some magnetic material to be located inside the air-core coils 3.

The main body tube portion 20 does not have to be annular when viewed in the axial direction. In addition, the main body tube portion 20 does not have to be formed by stacking multiple steel plates in the axial direction.

The material of the axial direction restricting portion 411 is not limited. The axial direction restricting portion 411 does not have to be made of the same material as the main body tube portion 20, but it is preferable that it be made of a magnetic material.

The axial regulating portion 411 does not have to be formed over the entire circumferential length of the end portion in the axial direction of the main body tubular portion 20. The axial regulating portion 411 may be formed partially in the circumferential direction of the end portion in the axial direction of the main body tubular portion 20. The axial regulating portion 411 only needs to be formed in at least the portion of the main body tubular portion 20 that corresponds to the air-core coils 3. In this case, the same number of axial regulating portions 411 as the number of air-core coils 3 are formed. Note that the number of air-core coils 3 provided in the main body tubular portion 20 is not limited.

The material of the radial regulating portion 412 is not limited. The radial regulating portion 412 does not have to be made of the same material as the main body tube portion 20, and does not have to be made of the same material as the axial regulating portion 411, but it is preferable that the radial regulating portion 412 is made of a magnetic material.

The radial regulating portion 412 does not have to be formed over the entire circumferential length of the main body tubular portion 20, and does not have to be formed over the entire circumferential length of the axial regulating portion 411. The radial regulating portion 412 may be formed partially in the circumferential length of the main body tubular portion 20. It is sufficient that the radial regulating portion 412 is formed at least in a portion of the main body tubular portion 20 that corresponds to the air-core coil 3. It is preferable that the radial regulating portion 412 is formed in the same position as the axial regulating portion 411 in the circumferential length of the main body tubular portion 20.

The first end restriction portion 41 and the main body tube portion 20 do not have to be formed integrally.

The material of the second end restriction portion 42 does not have to be the same as the material of the first end restriction portion 41, but it is preferable that it is the same as the material of the first end restriction portion 41.

The axial length of the circumferential regulating portion 43 is not particularly limited. The axial length of the circumferential regulating portion 43 can be fully functional as long as it is at least half the length of the portion corresponding to the air-core coil 3 in the axial direction.

The material of the circumferential regulating portion 43 is not limited. The circumferential regulating portion 43 does not have to be made of the same material as the main body tube portion 20, the axial regulating portion 411, or the radial regulating portion 412, but is preferably made of a magnetic material.

The material of the middle regulating portion 44 (first middle regulating portion 45 and second middle regulating portion 46) is not limited. The middle regulating portion 44 does not have to be made of the same material as the main body tube portion 20, but it is preferable that it is made of a magnetic material.

The middle restriction portion 44 and the main body tube portion 20 do not have to be formed integrally.

(13) Summary As is clear from the above-described embodiment and its modified examples, the stator (11) of the first aspect includes a yoke portion (2) and a plurality of air-core coils (3). The yoke portion (2) is annular around the axial center (10) of the rotor (12). The air-core coils (3) are disposed inside the yoke portion (2). The yoke portion (2) includes a main body tubular portion (20) and a movement restricting portion (4). The main body tubular portion (20) includes the air-core coils (3) disposed along the inner peripheral surface (21) to form a back yoke. The movement restricting portion (4) protrudes toward the axial center (10) from the main body tubular portion (20). The movement restricting portion (4) includes axial restricting portions (411, 421, 451, 461) and radial restricting portions (412, 422, 452, 462). The axial direction restricting portions (411, 421, 451, 461) restrict the air-core coil (3) from moving in the axial direction along which the axis (10) extends. The radial direction restricting portions (412, 422, 452, 462) restrict the air-core coil (3) from moving in the radial direction perpendicular to the axis (10).

According to the first aspect, the axial direction restricting portion (411, 421, 451, 461) restricts the axial movement of the air-core coil (3), and the radial direction restricting portion (412, 422, 452, 462) restricts the radial movement of the air-core coil (3). This makes it easier to position or attach the air-core coil (3) to a predetermined attachment position of the yoke portion (2).

The second aspect can be realized by combining it with the first aspect. In the second aspect, the yoke portion (2) has an end portion (40) formed at the end portion in the axial direction of the main body tube portion (20) as the movement restriction portion (4). The end portion (40) has an axial restriction portion (411, 421) that restricts the movement of the outer circumferential surface (31) of the air-core coil (3).

According to the second aspect, it becomes easier to position or attach the yoke portion (2) of the air-core coil (3) to a specified mounting position.

The third aspect can be realized by combining with the second aspect. In the third aspect, the yoke portion (2) has a first end regulating portion (41) and a second end regulating portion (42) as the end regulating portion (40). The first end regulating portion (41) is formed at a first end in the axial direction of the main body tubular portion (20). The second end regulating portion (42) is formed at a second end in the axial direction of the main body tubular portion (20).

The third aspect makes it easier to more firmly position and attach (fix) the air-core coil (3) to the yoke portion (2).

The fourth aspect can be realized by combining with the second or third aspect. In the fourth aspect, the radial restriction portion (412) is arranged over at least the entire length of the portion corresponding to the air-core coil (3) in the axial direction.

The fourth aspect makes it easier to more firmly position and attach (fix) the air-core coil (3) to the yoke portion (2).

The fifth aspect can be realized by combining it with any of the second to fourth aspects. In the fifth aspect, the end restriction portion (40) has a plurality of circumferential restriction portions (43) that restrict the air-core coil (3) from moving in the circumferential direction of the shaft center (10).

According to the fifth aspect, the circumferential movement of the air-core coil (3) is restricted.

The sixth aspect can be realized by combining with any of the second, fourth, or fifth aspects. In the sixth aspect, the main body tubular portion (20) has a non-movement-restricted end portion that does not have an end restriction portion (40) at one of both ends in the axial direction of the main body tubular portion (20). A groove portion (22) that holds a lead wire connected to the air-core coil (3) is formed at the non-movement-restricted end portion.

According to the sixth aspect, the lead wire can be passed through the inside and outside of the main body tube portion (20). In addition, the groove portion (22) is formed at the end portion in the axial direction of the main body tube portion (20), so the groove portion (22) can be easily formed.

The seventh aspect can be realized by combining it with any of the first to sixth aspects. In the seventh aspect, the yoke portion (2) has a middle portion restricting portion (44) formed in the middle portion of the main body tube portion (20) in the axial direction as the movement restricting portion (4). The middle portion restricting portion (44) has an axial direction restricting portion (451, 461) that restricts the movement of the inner peripheral surface (32) facing the hollow portion of the air-core coil (3).

According to the seventh aspect, it is easier to more firmly position and attach (fix) the air-core coil (3) to the yoke portion (2).

The eighth aspect can be realized by combining with the seventh aspect. In the eighth aspect, the main body tube portion (20) is configured with a plurality of assembly pieces (201) arranged in the circumferential direction of the axis (10) and has a middle portion regulating portion (44) attached thereto. Adjacent assembly pieces (201) among the plurality of assembly pieces (201) are connected to each other or integrated with a welded portion between them.

According to the eighth aspect, the air-core coil (3) can be attached to the middle regulating portion (44) of the assembly piece (201) before it is assembled to the main body tubular portion (20), making it easy to attach the air-core coil (3) to the main body tubular portion (20).

The ninth aspect can be realized by combining it with the seventh or eighth aspect. In the ninth aspect, a groove portion (22) for holding a lead wire connected to the air-core coil (3) is formed at the axial end of the main body tube portion (20).

According to the ninth aspect, the lead wire can be passed through the inside and outside of the main body tube portion (20). In addition, the groove portion (22) is formed at the end portion in the axial direction of the main body tube portion (20), so the groove portion (22) can be easily formed.

The tenth aspect can be realized by combining with the first aspect. In the tenth aspect, the yoke portion (2) has an end portion regulating portion (40) and a middle portion regulating portion (44) as the movement regulating portion (4). The end portion regulating portion (40) is formed at the end portion in the axial direction of the main body tubular portion (20). The middle portion regulating portion (44) is formed at the middle portion in the axial direction of the main body tubular portion (20).

According to the tenth aspect, it is easier to more firmly position and attach (fix) the air-core coil (3) to the yoke portion (2).

The eleventh aspect can be realized by combining it with any one of the first to tenth aspects. In the eleventh aspect, the coreless motor (1) includes a stator (11) of any one of the first to tenth aspects and a rotor (12).

According to the eleventh aspect, it becomes easier to position or attach the air-core coil (3) to a specified mounting position on the yoke portion (2) of the coreless motor (1).

REFERENCE SIGNS LIST 1 coreless motor 10 shaft core 11 stator 12 rotor 121 rotating shaft 122 rotor core 123 magnet 2 yoke portion 20 main body cylindrical portion 201 assembly piece 21 inner peripheral surface 22 groove portion 3 air-core coil 31 outer peripheral surface 32 inner peripheral surface 4 movement restricting portion 40 end restricting portion 41 first end restricting portion 411 axial restricting portion 412 radial restricting portion 42 second end restricting portion 421 axial restricting portion 422 radial restricting portion 43 circumferential restricting portion 44 middle restricting portion 45 first middle restricting portion 451 axial restricting portion 452 radial restricting portion 46 second middle restricting portion 461 axial restricting portion 462 radial restricting portion

Claims (11)

a yoke portion that is annular around an axis of the rotor;
a plurality of air-core coils disposed inside the yoke portion,
The yoke portion is
a main body cylindrical portion having the air-core coil disposed along an inner peripheral surface thereof and constituting a back yoke;
a movement restricting portion protruding toward the axis from the main body cylindrical portion,
The movement restriction portion is
an axial direction restricting portion that restricts the air-core coil from moving in an axial direction along which the shaft center extends;
and a radial direction restricting portion that restricts the air-core coil from moving in a radial direction perpendicular to the axis.
Stator. the yoke portion has an end portion restricting portion formed at an end portion in the axial direction of the main body cylindrical portion as the movement restricting portion,
The end portion restricting portion has an axial restriction portion that restricts movement of an outer circumferential surface of the air-core coil.
The stator according to claim 1 . The yoke portion serves as the end restriction portion.
a first end restriction portion formed at a first end portion in the axial direction of the main body cylindrical portion;
and a second end restriction portion formed at a second end portion in the axial direction of the main body cylindrical portion.
The stator according to claim 2 . The radial direction restricting portion is disposed over at least the entire length of the portion corresponding to the air-core coil in the axial direction.
The stator according to claim 2 . The end restriction portion has a plurality of circumferential restriction portions that restrict the air-core coil from moving in a circumferential direction of the axis.
The stator according to claim 2 . the main body tubular portion has a non-movement restricted end portion that does not have the end restriction portion at one of both ends in the axial direction of the main body tubular portion,
A groove for holding a lead wire connected to the air-core coil is formed in the non-movement-restricted end portion.
The stator according to claim 2 . the yoke portion has a middle portion restricting portion formed in a middle portion of the main body cylindrical portion in the axial direction as the movement restricting portion,
The intermediate portion restricting portion has an axial restricting portion that restricts movement of an inner circumferential surface of the air-core coil that faces a hollow portion of the air-core coil.
The stator according to claim 1 . the main body tubular portion is configured by a plurality of assembly pieces to which the intermediate portion restricting portion is attached and which are arranged in a circumferential direction of the axis,
Adjacent pieces of the plurality of assembly pieces are connected to each other or integrated with each other by having welds therebetween.
8. The stator according to claim 7. a groove for holding a lead wire connected to the air-core coil is formed at an end of the main body tube in the axial direction;
8. The stator according to claim 7. The yoke portion serves as the movement restriction portion.
an end restriction portion formed at an end portion in the axial direction of the main body cylindrical portion;
and a middle portion restricting portion formed in a middle portion of the main body cylindrical portion in the axial direction.
The stator according to claim 1 . A stator according to claim 1;
The rotor.
Coreless motor.

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