motor

Abstract

This technology provides a way to miniaturize motors without reducing their output. [Solution] The motor comprises a cylindrical body composed of a plurality of flat surfaces arranged circumferentially around a shaft and corners located at the boundaries of adjacent flat surfaces, a stator having a plurality of first teeth projecting outward from the outer surface of the cylindrical body and around which coils are wound, a plurality of second teeth with a greater number of coil turns than the first teeth, and a plurality of bolt mounting portions provided on the inner surface of the corners into which bolts for fixing the stator to the motor bracket are inserted. The plurality of flat surfaces are located inside a virtual circle passing through the plurality of corners where the bolt mounting portions are provided. The first teeth are formed on the outer surface of the corners where the bolt mounting portions are provided. The second teeth are formed on the outer surface of the flat surface opposite to the corners where the bolt mounting portions are provided, with the shaft in between.

Description

Technical Field

[0006] , , ,

[0001] The present invention relates to an outer rotor type motor.

Background Art

[0002] In recent years, efforts have been made to promote the Sustainable Development Goals (the 2030 Agenda for Sustainable Development, adopted at the United Nations Summit on September 25, 2015, hereinafter referred to as "SDGs"). Along with this, technologies aiming at reducing waste and defective products are known in order to ensure sustainable production and consumption patterns. [[ID=​​​​​​​​​​​​​​​​​​​​​​​​​​​​When attempting to miniaturize such an outer rotor type motor in the radial direction, reducing the tooth protrusion reduces the number of coil turns, thus decreasing motor output. On the other hand, changing the pitch of the bolt mounting holes requires redesigning the motor bracket and other components from scratch, making it difficult to simply reduce the diameter of the cylindrical body while maintaining the tooth protrusion.

[0007] This invention has been made in view of the above circumstances, and its purpose is to provide a technology for miniaturizing a motor without reducing its output. [Means for solving the problem]

[0008] To achieve the above objective, the present invention provides a motor comprising a motor bracket, a shaft fixed to the motor bracket, a rotor rotatably supported on the shaft, and a stator fixed to the motor bracket inside the rotor and generating a magnetic field for rotating the rotor, wherein the stator comprises a cylindrical body composed of a plurality of flat surfaces arranged circumferentially around the shaft and corners located at the boundaries of adjacent flat surfaces, a plurality of first teeth with coils wound around them protruding outward from the outer surface of the cylindrical body, a plurality of second teeth with more coil turns than the first teeth, and a plurality of bolt mounting portions provided on the inner surface of the corners into which bolts for fixing the stator to the motor bracket are inserted, wherein the plurality of flat surfaces are located inside a virtual circle passing through the plurality of corners where the bolt mounting portions are provided, the first teeth are formed on the outer surface of the corners where the bolt mounting portions are provided, and the second teeth are formed on the outer surface of the flat surface opposite to the corners where the bolt mounting portions are provided, with the shaft in between. [Effects of the Invention]

[0009] According to the present invention, the motor can be miniaturized without reducing the motor output. Other problems, configurations, and effects will be clarified by the following description of the embodiments. [Brief explanation of the drawing]

[0010] [Figure 1] This is an external perspective view showing one example configuration of a fan device according to the embodiment. [Figure 2] This is a disassembled perspective view of the motor and fan after they have been taken apart. [Figure 3] This is a perspective view of the motor from the front. [Figure 4] This is a cross-sectional view of the brushless motor at IV-IV in Figure 3. [Figure 5] Figure 4 is a cross-sectional view of the stator in VV. [Figure 6] This diagram shows the coil's wiring configuration (delta connection). [Figure 7] This is a diagram of the stator windings. [Figure 8] This is a cross-sectional view of the stator in a modified form. [Modes for carrying out the invention]

[0011] Hereinafter, as one embodiment of the fan device according to the present invention, a fan device 1 mounted on a vehicle such as an automobile and used to cool engine coolant flowing in a radiator will be described. However, the use of the motor 2 according to this embodiment is not limited to the fan device 1.

[0012] [Overall configuration of fan device 1] First, the overall configuration of the fan device 1 will be described with reference to Figures 1 and 2. Figure 1 is an external perspective view showing one example configuration of the fan device 1 according to the embodiment. Figure 2 is an exploded perspective view when the motor 2 and fan 3 are separated. As shown in Figures 1 and 2, the fan device 1 comprises a motor 2, which is the drive source, and a fan 3, which is rotated by the motor 2 to generate cooling air.

[0013] [Fan 3 configuration] As shown in FIGS. 1 and 2, the fan 3 includes a boss portion 31 that rotates integrally with the rotor 23 about the axis of the shaft 21 as the rotation center, a plurality (seven in this embodiment) of blades 32 radially projecting from the outer periphery of the boss portion 31, and a plurality (seven in this embodiment) of connecting members 33 that connect adjacent blades 32 to each other at the tip side.

[0014] Further, the boss portion 31 includes a disk-shaped disk portion 311 and a cylindrical peripheral wall portion 312 that protrudes from the outer edge of the disk portion 311 toward the motor 2 and to which the plurality of blades 32 are attached. When the fan 3 is attached to the motor 2, the disk portion 311 faces the connecting wall 232c of the rotor yoke 232, and the peripheral wall portion 312 surrounds the outer peripheral wall 232a of the rotor yoke 232.

[0015] As shown in FIG. 2, the fan 3 is fastened to the rotor yoke 232 by screws 10. In this embodiment, in consideration of the rotational balance of the fan 3, the three screws 10 are attached at equal intervals on the circumference centered on the rotation center of the fan 3. Note that it is not necessarily required to use the three screws 10 as the fastening members for fastening the fan 3 to the motor 2, and there are no particular restrictions on the number of screws 10 and the types of fastening members as long as the fan 3 can be fastened to the motor 2.

[0016] [Configuration of Motor 2] Next, referring to FIGS. 3 and 4, the configuration of the motor 2 will be described. FIG. 3 is an external perspective view of the motor 2 as viewed from the front side. FIG. 4 is a cross-sectional view of the brushless motor 201 at IV-IV in FIG. 3. As shown in FIG. 4, the motor 2 is a so-called "mechatronic" electric motor including an outer rotor type brushless motor 201 and a driver circuit 202 that controls the brushless motor 201 (more specifically, the generation of a magnetic field by the coil 44).

[0017] The brushless motor 201 is supported by a plate-shaped motor bracket 203. The brushless motor 201 is disposed on one side (front surface side) in the thickness direction of the motor bracket 203. In the present embodiment, an example of a 10-pole 12-slot brushless motor 201 will be described. However, the number of poles and slots of the brushless motor 201 is not limited to the above example, and for example, 8 poles 12 slots, 4 poles 6 slots (modified example) may also be used.

[0018] On the other side (back surface side) in the thickness direction of the motor bracket 203, a driver bracket 204 is fastened by a plurality of screws (not shown). Thereby, an accommodation space 206 is formed between the motor bracket 203 and the driver bracket 204. And the driver circuit 202 is accommodated in this accommodation space 206.

[0019] Also, at the end of the motor bracket 203, a connector unit 207 in which two connectors to which an external harness is connected are integrated is attached. The brushless motor 201, the driver circuit 202, and the connector unit 207 are electrically connected to each other via the motor bracket 203.

[0020] As shown in FIGS. 3 and 4, the brushless motor 201 includes a shaft 21, bearings 22a and 22b provided on the outer periphery of the shaft 21, a rotor 23 rotatably supported around the axis of the shaft 21 via the bearings 22a and 22b, and a stator 24 that generates a magnetic field for rotating the rotor 23.

[0021] [[ID=Hex16]]The shaft 21 is a fixed shaft fixed to the front surface side of the motor bracket 203. Hereinafter, in the description of the components of the motor 2, the axial direction of the shaft 21 will be simply referred to as the "axial direction", the radial direction centered on the axis of the shaft 21 will be simply referred to as the "radial direction", and the circumferential direction centered on the axis of the shaft 21 will be simply referred to as the "circumferential direction".

[0022] The rotor 23 has a plurality of permanent magnets 231 arranged at equal intervals in the circumferential direction so as to surround the outer circumference of the stator 24, and a rotor yoke 232 that covers the stator 24 and the plurality (10 in this embodiment) permanent magnets 231. The rotor yoke 232 is positioned on the surface side of the motor bracket 203 so as to be concentric with the axis of the shaft 21. The rotor yoke 232 is also rotatably supported on the shaft 21 via bearings 22a and 22b. The rotor yoke 232 mainly comprises an outer circumferential wall 232a, an inner circumferential wall 232b, and a connecting wall 232c.

[0023] The outer periphery wall 232a has a cylindrical shape. Furthermore, the outer periphery wall 232a is positioned radially outward from the stator 24. In addition, the outer periphery wall 232a supports multiple permanent magnets 231 on its inner surface. In other words, the multiple permanent magnets 231 are fixed to the inner surface of the outer periphery wall 232a, spaced apart in the circumferential direction to surround the stator 24.

[0024] The inner circumferential wall 232b has a cylindrical outer shape. Furthermore, the inner circumferential wall 232b is positioned radially inward from the stator 24. In addition, the inner circumferential wall 232b is rotatably supported by the shaft 21 via bearings 22a and 22b.

[0025] The connecting wall 232c has a disc-shaped outer form. The connecting wall 232c also connects the axial ends of the outer circumferential wall 232a and the inner circumferential wall 232b. More specifically, as shown in Figure 4, the connecting wall 232c connects the outer circumferential wall 232a and the inner circumferential wall 232b at the other axial end of the shaft 21 (i.e., the side opposite to the motor bracket 203).

[0026] The stator 24 is housed in a space enclosed by the outer peripheral wall 232a, the inner peripheral wall 232b, the connecting wall 232c, and the motor bracket 203. As shown in Figure 4, the stator 24 is fixed to the surface side of the motor bracket 203, radially inward from the multiple permanent magnets 231. Furthermore, the stator 24 faces the multiple permanent magnets 231 with a predetermined gap separating them radially.

[0027] Figure 5 is a cross-sectional view of the stator 24 in VV of Figure 4. The stator 24 consists of a stator core 40 having a cylindrical body 41, a plurality of teeth 42 (12 in this embodiment), and a plurality of bolt mounting portions 43 (3 in this embodiment), and a plurality of coils 44 (12 in this embodiment).

[0028] The stator core 40 is formed, for example, by multiple steel plates stacked in the axial direction. The stator core 40 is constructed by covering the stacked steel plates with an insulating insulator. The coil 44 is wound around the teeth 42 over the insulator. The stator 24 generates a magnetic field to rotate the rotor 23 when current flows through the coil 44.

[0029] The cylindrical body 41 according to this embodiment has a nonagonal cross-section perpendicular to the extending direction of the shaft 21 and exhibits a cylindrical outer shape extending in the extending direction of the shaft 21. The cylindrical body 41 is composed of nine flat surfaces 47a to 47i and nine corners 46a to 46i. The flat surfaces 47a to 47i are arranged in the circumferential direction so as to surround the shaft 21 and bearings 22a and 22b. The corners 46a to 46i are located at the boundaries of adjacent flat surfaces 47a to 47i in the circumferential direction. The corners 46a to 46i may be chamfered. The cylindrical body 41 has an inner surface and an outer surface.

[0030] On the opposite sides of the center O of the shaft 21 from the corners 46a, 46d, and 46g, flat surfaces 47e, 47h, and 47b are formed. Furthermore, the flat surfaces 47a, 47f, 47c, 47g, 47d, and 47i are located on opposite sides of the center O of the shaft 21 and are arranged parallel to each other.

[0031] Of the nine corners 46a to 46i, the three corners 46a, 46d, and 46g, which are equally spaced (120° apart), are located further from the center O of the shaft 21 than the other six corners 46b, 46c, 46e, 46f, 46h, and 46i. Furthermore, all the flat surfaces 47a to 47i are located inside a virtual circle C (shown as a dashed line in Figure 5) of the center O that passes through the corners 46a, 46d, and 46g.

[0032] Multiple teeth 42 protrude radially from the outer surface of the cylindrical body 41. In other words, multiple teeth 42 protrude radially outward from positions spaced apart in the circumferential direction on the outer surface of the cylindrical body 41. To put it another way, the teeth 42 include teeth 42U1, 42W5, and 42V9 that protrude radially outward from the corners 46a, 46d, and 46g, and teeth 42U2, 42V3, 42V4, 42W6, 42U7, 42U8, 42V10, 42W11, and 42W12 that protrude radially outward from the flat surfaces 47a to 47i.

[0033] Teeth 42U1, 42W5, and 42V9 protrude in the direction of a straight line passing through the center O of the shaft 21 and the corners 46a, 46d, and 46g (in other words, in the direction of the normal to the virtual circle C at the positions of corners 46a, 46d, and 46g). Additionally, teeth 42U2, 42V3, 42V4, 42W6, 42U7, 42U8, 42V10, 42W11, and 42W12 protrude from the circumferential center of the flat surfaces 47a to 47i in a direction perpendicular to the flat surfaces 47a to 47i.

[0034] Furthermore, the protruding ends of all teeth 42 are at the same distance from the center O. On the other hand, the flat surfaces 47a to 47i are located radially inward from the corners 46a, 46d, and 46g, so the protrusion amount (radial length) of teeth 42U2, 42V3, 42V4, 42W6, 42U7, 42U8, 42V10, 42W11, and 42W12 is greater than the protrusion amount of teeth 42U1, 42W5, and 42V9. In other words, the number of turns of coil 44 that can be wound around teeth 42U2, 42V3, 42V4, 42W6, 42U7, 42U8, 42V10, 42W11, and 42W12 is greater than that of teeth 42U1, 42W5, and 42V9.

[0035] The bolt mounting portions 43a, 43b, and 43c are provided on the inner surfaces of the corner portions 46a, 46d, and 46g. More specifically, the bolt mounting portions 43a, 43b, and 43c protrude radially inward from the inner surfaces of the corner portions 46a, 46d, and 46g. Furthermore, through holes are formed in the bolt mounting portions 43a, 43b, and 43c that extend in the direction of extension of the shaft 21.

[0036] Then, bolts 208 (see Figure 4) for fixing the stator 24 to the motor bracket 203 are inserted through the through holes of the bolt mounting portions 43a, 43b, and 43c. More specifically, the bolts 208 that have passed through the through holes of the bolt mounting portions 43a, 43b, and 43c are screwed into bolt holes formed on the surface of the motor bracket 203. This fixes the stator 24 to the motor bracket 203.

[0037] Figure 6 shows the wiring configuration (delta connection) of coil 44. Figure 7 is an unfolded view of the windings of stator 24. As shown in Figures 6 and 7, coil 44 includes coils 44U1, 44U2, 44U7, and 44U8 through which U-phase current flows, coils 44V3, 44V4, 44V9, and 44V10 through which V-phase current flows, and coils 44W5, 44W6, 44W11, and 44W12 through which W-phase current flows.

[0038] Coils 44U1, 44U2, 44U7, and 44U8 are wound around teeth 42U1, 42U2, 42U7, and 42U8. Furthermore, coils 44U1, 44U2, 44U7, and 44U8 are connected in series. That is, one winding is wound around teeth 42U1, 42U2, 42U7, and 42U8 in the order of coils 44U1, 44U2, 44U7, and 44U8.

[0039] Coils 44V3, 44V4, 44V9, and 44V10 are wound around teeth 42V3, 42V4, 42V9, and 42V10. Furthermore, coils 44V3, 44V4, 44V9, and 44V10 are connected in series. That is, a single winding is used to create coils 44V3, 44V4, 44V9, and 44V10, wound around teeth 42V3, 42V4, 42V9, and 42V10 in that order.

[0040] Coils 44W5, 44W6, 44W11, and 44W12 are wound around teeth 42W5, 42W6, 42W11, and 42W12. Furthermore, coils 44W5, 44W6, 44W11, and 44W12 are connected in series. That is, one winding is wound around teeth 42W5, 42W6, 42W11, and 42W12 in the order of coils 44W5, 44W6, 44W11, and 44W12.

[0041] Furthermore, one end of the windings constituting coils 44U1, 44U2, 44U7, and 44U8 is connected to one end of the windings constituting coils 44V3, 44V4, 44V9, and 44V10. Also, the other end of the windings constituting coils 44V3, 44V4, 44V9, and 44V10 is connected to one end of the windings constituting coils 44W5, 44W6, 44W11, and 44W12. In addition, the other end of the windings constituting coils 44W5, 44W6, 44W11, and 44W12 is connected to the other end of the windings constituting coils 44U1, 44U2, 44U7, and 44U8. In other words, coils 44U1, 44U2, 44U7, and 44U8, coils 44V3, 44V4, 44V9, and 44V10, and coils 44W5, 44W6, 44W11, and 44W12 are delta-connected.

[0042] The U-phase coil 44U1 is wound around the tooth 42U1 formed at the corner 46a provided with the bolt attachment portion 43a. The coil 44U2 is wound around the tooth 42U2 formed on the flat surface 47a adjacent to one side (for example, counterclockwise) in the circumferential direction with respect to the corner 46a. The coil 44U7 is wound around the tooth 42U7 formed on the flat surface 47e on the opposite side of the corner 46a across the center O of the shaft 21. The coil 44U8 is wound around the tooth 42U8 formed on the flat surface 47f adjacent to one side in the circumferential direction with respect to the flat surface 47e.

[0043] The first number of turns T1 of the coils 44U1 and 44U8 wound around the teeth 42U1 and 42U8 is set to be less than the second number of turns T2 of the coils 44U2 and 44U7 wound around the teeth 42U2 and 42U7 (T1 < T2). The teeth 42U1 and 42U8 are an example of the first teeth, and the teeth 42U2 and 42U7 are an example of the second teeth.

[0044] That is, the coil 44U1 with the first number of turns T1 is wound around the tooth 42U1 formed at the corner 46a provided with the bolt attachment portion 43a. Also, the coil 44U2 with the second number of turns T2 is wound around the tooth 42U2 adjacent to one side in the circumferential direction of the tooth 42U1. Further, the coil 44U7 with the second number of turns T2 is wound around the tooth 42U7 on the opposite side of the tooth 42U1 across the center O of the shaft 21. Moreover, the coil 44U8 with the first number of turns T1 is wound around the tooth 42U8 adjacent to one side in the circumferential direction of the tooth 42U7.

[0045] The V-phase coil 44V9 is wound around the tooth 42V9 formed at the corner 46g provided with the bolt attachment portion 43c. The coil 44V10 is wound around the tooth 42V10 formed on the flat surface 47g adjacent to one side in the circumferential direction with respect to the corner 46g. The coil 44V3 is wound around the tooth 42V3 formed on the flat surface 47b on the opposite side of the corner 46g across the center O of the shaft 21. The coil 44V4 is wound around the tooth 42V4 formed on the flat surface 47c adjacent to one side in the circumferential direction with respect to the flat surface 47b.

[0046] The first number of turns T1 of coils 44V4 and 44V9 wound around teeth 42V4 and 42V9 is set to be less than the second number of turns T2 of coils 44V3 and 44V10 wound around teeth 42V3 and 42V10. Teeth 42V4 and 42V9 are examples of first teeth, and teeth 42V3 and 42V10 are examples of second teeth. In other words, the layout of the V-phase coils 44V3, 44V4, 44V9, and 44V10 corresponds to the layout of the U-phase coils 44U1, 44U2, 44U7, and 44U8, shifted 120° to the other side in the circumferential direction (clockwise).

[0047] The W-phase coil 44W5 is wound around teeth 42W5 formed on corner 46d where a bolt mounting portion 43b is provided. The coil 44W6 is wound around teeth 42W6 formed on a flat surface 47d adjacent to corner 46d on one side in the circumferential direction. The coil 44W11 is wound around teeth 42W11 formed on a flat surface 47h opposite corner 46d, with the center O of the shaft 21 in between. The coil 44W12 is wound around teeth 42W12 formed on a flat surface 47i adjacent to flat surface 47h on one side in the circumferential direction.

[0048] The first number of turns T1 of coils 44W5 and 44W12 wound around teeth 42W5 and 42W12 is set to be less than the second number of turns T2 of coils 44W6 and 44W11 wound around teeth 42W6 and 42W11. Teeth 42W5 and 42W12 are examples of first teeth, and teeth 42W6 and 42W11 are examples of second teeth. In other words, the layout of the W-phase coils 44W5, 44W6, 44W11, and 44W12 corresponds to the layout of the U-phase coils 44U1, 44U2, 44U7, and 44U8, shifted 120° to one side (counterclockwise) in the circumferential direction.

[0049] Thus, the teeth 42U1, 42W5, and 42V9 formed on the corners 46a, 46d, and 46g where the bolt mounting portions 43a, 43b, and 43c are provided are wound with coils 44U1, 44W5, and 44V9 of different phases. Furthermore, the teeth 42U1, 42U7, 42U2, 42U8, 42V3, 42V9, 42V4, 42V10, 42W5, 42W11, 42W6, and 42W12 on the opposite side of the center O of the shaft 21 are wound with coils of the same phase, but with different numbers of turns. In addition, the total number of turns of the coils wound on two teeth located on opposite sides of the center O of the shaft 21 is the same, T1 + T2.

[0050] [Effects of the Embodiment] In the brushless motor 201 according to the above embodiment, the size of the virtual circle C in Figure 5 is set to match the contour line of the cylindrical body in Patent Document 1. This allows the pitch of the bolt mounting portions 43a, 43b, and 43c to be the same as in the conventional design. On the other hand, if the radial size of the brushless motor 201 is made smaller than that of the motor in Patent Document 1, the number of turns of the coils 44U1, 44W5, and 44V9 of the teeth 42U1, 42W5, and 42V9 formed on the corner portions 46a, 46d, and 46g decreases. Therefore, by arranging the flat surfaces 47e, 47h, and 47b inside the virtual circle C, the amount of protrusion of the teeth 42U7, 42W11, and 42V3 can be increased compared to Patent Document 1, thus increasing the number of turns of the coils 44U7, 44W11, and 44V3.

[0051] Here, assuming the number of permanent magnets 231, the effective magnetic flux, and the magnitude of the current flowing through the coil 44 are the same, the output of the brushless motor 201 is determined by the total number of turns of the coil 44. Therefore, compared to the number of turns T0 (for example, 16 turns) of each coil in Patent Document 1, the first number of turns T1 (for example, 14 turns) of coils 44U1, 44W5, and 44V9 is reduced, and the second number of turns T2 (for example, 18 turns) of coils 44U7, 44W11, and 44V3 is increased. Also, T0 = (T1 + T2) / 2. This makes it possible to miniaturize the brushless motor 201 without reducing the motor output.

[0052] On the other hand, if the radial size of the brushless motor 201 is the same as that of the motor in Patent Document 1, the number of turns of coils 44U1, 44W5, and 44V9 will be the same as in Patent Document 1, and the number of turns of coils 44U7, 44W11, and 44V3 can be increased compared to Patent Document 1. As a result, the motor output can be increased without increasing the size of the brushless motor 201.

[0053] Furthermore, according to the above embodiment, not only are the number of turns of coils 44U1, 44W5, and 44V9 at the corners 46a, 46d, and 46g reduced, but the number of turns of coils 44U8, 44V4, and 44W12 are also reduced, and instead the number of turns of coils 44U2, 44V10, and 44W6 are increased. As a result, the sum of the number of turns (T1 + T2) of the two coils positioned on opposite sides of the center O of the shaft 21 can be kept constant over the entire circumference, thereby reducing the output fluctuation due to the rotation angle.

[0054] However, from the perspective of increasing motor output, the number of turns of coils 44U1, 44W5, and 44V9 at the corners 46a, 46d, and 46g may be set to the first number of turns T1, and the number of turns of all coils 44U2, 44V3, 44V4, 44W6, 44U7, 44U8, 44V10, 44W11, and 44W12 at the flat surfaces 47a to 47i may be set to the second number of turns T2.

[0055] Furthermore, according to the above embodiment, by orienting the teeth 42U2, 42V3, 42V4, 42W6, 42U7, 42U8, 42V10, 42W11, and 42W12 perpendicular to the flat surfaces 47a to 47i, it becomes easier to increase the number of turns of the coils 44U2, 44V3, 44V4, 44W6, 44U7, 44U8, 44V10, 44W11, and 44W12 compared to having the teeth protrude from the cylindrical surface as in Patent Document 1.

[0056] [Differentiation] Figure 8 is a cross-sectional view of a modified stator 24A. Detailed explanations of the similarities with the above embodiment will be omitted, and the differences will be the focus of this explanation. The modified stator 24A consists of a stator core 50 comprising a cylindrical body 51, a plurality of teeth 52 (six in this embodiment), and a plurality of bolt mounting portions 53 (three in this embodiment), and a plurality of coils 54 (six in this embodiment).

[0057] The modified cylindrical body 51 has a triangular cross-section perpendicular to the extension direction of the shaft 21 and exhibits a cylindrical outer shape extending in the extension direction of the shaft 21. The cylindrical body 51 is composed of three flat surfaces 57a to 57c and three corners 56a to 56c. The flat surfaces 57a to 57c are arranged circumferentially to surround the shaft 21 and bearings 22a and 22b. The corners 56a to 56c are located at the boundaries of adjacent flat surfaces 57a to 57c in the circumferential direction. The corners 56a to 56c may be chamfered. The cylindrical body 51 has an inner surface and an outer surface. Furthermore, the flat surfaces 57a, 57b, and 57c are formed on the opposite side of the corners 56a, 56b, and 56c, with the center O of the shaft 21 in between.

[0058] Multiple teeth 52 protrude radially from the outer surface of the cylindrical body 51. In other words, multiple teeth 52 protrude radially outward from positions spaced apart in the circumferential direction on the outer surface of the cylindrical body 51. To put it another way, the teeth 52 include teeth 52U1, 52W3, and 52V5 that protrude radially outward from the corners 56a, 56b, and 56c, and teeth 52U4, 52W6, and 52V2 that protrude radially outward from the flat surfaces 57a to 57c. Teeth 52U1, 52W3, and 52V5 protrude in the direction of a straight line passing through the center O of the shaft 21 and the corners 56a, 56b, and 56c. Teeth 52U4, 52W6, and 52V2 protrude from the circumferential center of the flat surfaces 57a to 57c in a direction perpendicular to the flat surfaces 57a to 57c.

[0059] The bolt mounting sections 53a, 53b, and 53c are provided on the inner surfaces of the corner sections 56a, 56b, and 56c. Bolts for fixing the stator 24A to the motor bracket 203 are inserted through the bolt mounting sections 53a, 53b, and 53c. This fixes the stator 24A to the motor bracket 203.

[0060] The U-phase coil 54U1 is wound around a tooth 52U1 formed on a corner 56a where a bolt mounting portion 53a is provided. The coil 54U4 is wound around a tooth 52U4 formed on a flat surface 57a opposite the corner 56a, with the center O of the shaft 21 in between. The first number of turns T1 of the coil 54U1 wound around tooth 52U1 is set to be less than the second number of turns T2 of the coil 54U4 wound around tooth 52U4. Tooth 52U1 is an example of a first tooth, and tooth 52U4 is an example of a second tooth.

[0061] The W-phase coil 54W3 is wound around teeth 52W3 formed on a corner 56b where a bolt mounting portion 53b is provided. The coil 54W6 is wound around teeth 52W6 formed on a flat surface 57b opposite the corner 56b, with the center O of the shaft 21 in between. The first number of turns T1 of the coil 54W3 wound around teeth 52W3 is set to be less than the second number of turns T2 of the coil 54W6 wound around teeth 52W6. Teeth 52W3 is an example of a first tooth, and teeth 52W6 is an example of a second tooth.

[0062] The V-phase coil 54V5 is wound around teeth 52V5 formed on a corner 56c where a bolt mounting portion 53c is provided. The coil 54V2 is wound around teeth 52V2 formed on a flat surface 57c opposite the corner 56c, with the center O of the shaft 21 in between. The first number of turns T1 of the coil 54V5 wound around teeth 52V5 is set to be less than the second number of turns T2 of the coil 54V2 wound around teeth 52V2. Teeth 52V5 is an example of a first tooth, and teeth 52V2 is an example of a second tooth.

[0063] Thus, the teeth 52U1, 52W3, and 52V5 formed on the corners 56a, 56b, and 56c where the bolt mounting portions 53a, 53b, and 53c are provided are wound with coils 54U1, 54W3, and 54V5 of different phases. Furthermore, the teeth 52U1, 52U4, 52V2, 52V5, 52W3, and 52W6 on the opposite side of the center O of the shaft 21 are wound with coils of the same phase, but with different numbers of turns. Moreover, the total number of turns of the coils wound on two teeth located on opposite sides of the center O of the shaft 21 is the same, T1 + T2.

[0064] In other words, in the modified stator 24A, the first teeth 52U1, 52W3, 52V5, the second teeth 52V2, 52U4, 52W6, and the bolt mounting portions 53a, 53b, 53c are each provided in three locations. Thus, the present invention can be applied to, for example, a 4-pole, 6-slot motor.

[0065] Embodiments of the present invention have been described above. It should be noted that the present invention is not limited to the embodiments described above, and various modifications are included. For example, the embodiments described above are described in detail to make the present invention easier to understand, and are not necessarily limited to those having all the described configurations. Furthermore, it is possible to replace some of the configurations of this embodiment with those of other embodiments, and it is also possible to add configurations from other embodiments to the configuration of this embodiment. Moreover, it is possible to add, delete, or replace some of the configurations of this embodiment with those of other embodiments. [Explanation of Symbols]

[0066] 1: Fan device 2: Motor 3: Fan 10: Screws 21: Shaft 22: Bearings 23: Rotor 24,24A: Stator 31: Boss Department 32: Feather 33: Connecting member 40, 50: Stator core 41,51:Cylinder 42,52: Teeth 43, 53: Bolt mounting section 44,54: Coil 46, 56: Corner 47,57 :Flat surface 201: Brushless motor 202: Driver Circuit 203: Motor bracket 204: Driver bracket 206: Containment Space 207: Connector Unit 208: Bolt 231: Permanent magnet 232: Rotor yoke 232a: Outer wall 232b: Inner peripheral wall 232c: Connecting wall 311: Disc section 312: Peripheral wall part

Claims

1. Motor bracket and A shaft fixed to the motor bracket, A rotor rotatably supported on the aforementioned shaft, A motor comprising a stator fixed to the motor bracket inside the rotor and generating a magnetic field for rotating the rotor, The stator is, A cylindrical body comprising a plurality of flat surfaces arranged circumferentially to surround the shaft, and corners located at the boundaries of adjacent flat surfaces, The cylindrical body has a plurality of first teeth on which a coil is wound, protruding outward from the outer surface, and a plurality of second teeth with a greater number of coil turns than the first teeth, The inner surface of the aforementioned corner portion is provided with a plurality of bolt mounting portions into which bolts for fixing the stator to the motor bracket are inserted, The plurality of flat surfaces are located inside a virtual circle that passes through the plurality of corners where the bolt mounting portions are provided. The first teeth are formed on the outer surface of the corner portion where the bolt mounting portion is provided. The motor is characterized in that the second teeth are formed on the outer surface of the flat surface opposite to the corner portion where the bolt mounting portion is provided, with the shaft in between.

2. In the motor according to claim 1, The cylindrical body is composed of nine flat surfaces and nine corners. The bolt mounting portions are provided at three equally spaced locations among the nine corner portions. The motor is characterized in that the first teeth and the second teeth are formed on the three corners where the bolt mounting portions are provided and on the nine flat surfaces.

3. In the motor according to claim 2, The second teeth are also formed on the flat surface adjacent to the corner portion on one side in the circumferential direction with respect to the corner portion on which the bolt mounting portion is provided. The motor is characterized in that the first teeth are also formed on the flat surface adjacent to the flat surface on the opposite side in the circumferential direction to the flat surface on the opposite side of the corner where the bolt mounting portion is provided, with respect to the shaft.

4. In the motor according to claim 1, A motor characterized in that the first teeth, the second teeth, and the bolt mounting portion are each provided in three locations.

5. In the motor according to claim 1, The motor is characterized in that the second teeth protrude in a direction perpendicular to the flat surface.

6. In the motor according to claim 1, A motor characterized by comprising a bearing disposed inside the cylindrical body, which rotatably supports the rotor with respect to the shaft.

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